JP4319171B2 - Method for evaluating resist composition - Google Patents

Description

  The present invention relates to a method for evaluating a resist composition used in a resist pattern forming method including an immersion lithography (immersion exposure) step.

Lithography is frequently used to manufacture fine structures in various electronic devices such as semiconductor devices and liquid crystal devices. However, with the miniaturization of device structures, it is required to make resist patterns finer in the lithography process.
At present, it is possible to form a fine resist pattern having a line width of about 90 nm in a state-of-the-art region using, for example, an ArF excimer laser by lithography. Is required.
In order to achieve such a pattern formation finer than 90 nm, the development of an exposure apparatus and a corresponding resist is the first. In an exposure apparatus, it is common to shorten the wavelength of a light source such as an F ₂ laser, EUV (extreme ultraviolet light), electron beam, X-ray, or to increase the numerical aperture (NA) of a lens.
However, shortening the wavelength of the light source requires a new expensive exposure apparatus, and in increasing the NA, there is a trade-off between the resolution and the depth of focus. There is a problem that decreases.

Under such circumstances, a method called immersion lithography has been reported (for example, see Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3). This method uses a solvent having a refractive index larger than the refractive index of air, for example, pure water, at a portion between a lens and a resist layer on the wafer, which has conventionally been an inert gas such as air or nitrogen, during exposure. Alternatively, it is filled with a solvent such as a fluorine-based inert liquid. By filling with such a solvent, high resolution can be achieved at the same time as when a light source with the same exposure wavelength is used or when a light source with a shorter wavelength is used or when a high NA lens is used. It is said that there is no decrease in depth.
If such immersion lithography is used, it is possible to realize a resist pattern that has low cost, high resolution, and excellent focal depth by using a lens mounted on an existing apparatus. Attention has been paid.
Journal of Vacuum Science & Technology B (USA), 1999, Vol. 17, No. 6, pp. 3306-3309. Journal of Vacuum Science & Technology B (USA), 2001, Vol. 19, No. 6, pp. 2353-2356. Proceedings of SPIE (USA) 2002, 4691, pp. 459-465.

As described above, the advantage of immersion lithography is expected to have a great effect on the semiconductor industry in terms of cost and lithography characteristics such as resolution in the manufacture of semiconductor devices that require a large capital investment. However, as described above, the resist layer comes into contact with the solvent at the time of exposure, so that the resist layer is changed in quality, and the refractive index of the solvent is changed by exuding components that adversely affect the solvent from the resist. There are problems such as loss of the original advantages of immersion lithography, and there are still many unknown points as to whether a resist pattern as good as the conventional normal exposure process can be formed. In fact, when a certain kind of conventional KrF resist or ArF resist composition is applied to immersion lithography, it is affected by the solvent, the sensitivity is deteriorated, and the resist pattern surface has a T-top shape. There has been a problem of roughening (profile shape deterioration) or swelling of the resist pattern.
The present invention has been made in view of the problems of the prior art, and is not easily affected by the solvent used in the immersion lithography process without impairing the improvement in resolution and depth of focus, which are the advantages of immersion lithography. It is an object of the present invention to provide a method for evaluating a positive or negative resist composition that is excellent in sensitivity and resist pattern profile shape and that is used in a resist pattern forming method including an immersion lithography process.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention.
The method for evaluating a resist composition of the present invention is a method for evaluating a resist composition used in a resist pattern forming method including a step of immersion exposure,
A resist film is formed, selectively exposed, and subjected to a treatment for contacting the resist film with an immersion solvent used in the immersion exposure process, post-exposure heating (PEB), developed, and the resulting resist pattern formation performance is obtained. It includes a step of evaluating and judging whether or not it is suitable as a resist composition used in a resist pattern forming method including a step of immersion exposure .
The solvent is preferably a solvent having a refractive index larger than that of air and smaller than that of the resist film.
The solvent is preferably water.
In making the present invention, the inventors analyzed the method for evaluating the suitability of a resist film used in a resist pattern forming method including an immersion exposure process as follows, and based on the analysis results, the resist composition And a resist pattern forming method using the composition were evaluated.
That is, to evaluate the resist pattern formation performance by immersion exposure, (i) the performance of the optical system by immersion exposure, (ii) the influence of the resist film on the immersion solvent, (iii) the alteration of the resist film by the immersion solvent, If these three points can be confirmed, it is determined that it is necessary and sufficient.
As for the performance of the optical system (i), for example, it is clear that the surface water-resistant photographic photosensitive plate is submerged in water and the surface is irradiated with pattern light. In principle, there is no doubt that there will be no problem if there is no light propagation loss such as reflection at the interface between the substrate and the photosensitive plate surface. The light propagation loss in this case can be easily solved by optimizing the incident angle of the exposure light. Therefore, whether the object to be exposed is a resist film, a photographic photosensitive plate, or an imaging screen, if they are inert to the immersion solvent, that is, from the immersion solvent. If it is not affected and does not affect the immersion solvent, it can be considered that there is no change in the performance of the optical system. Therefore, this point is not necessary for a new confirmation experiment.
Specifically, the influence of the resist film on the immersion solvent (ii) is that the components of the resist film are dissolved in the liquid and the refractive index of the immersion solvent is changed. If the refractive index of the immersion solvent is changed, the optical resolution of the pattern exposure is surely changed from the theory without undergoing experimentation. Regarding this point, it is sufficient if it can be confirmed that when a resist film is immersed in an immersion solvent, a certain component is dissolved and the composition of the immersion solvent is changed or the refractive index is changed. Yes, it is not necessary to actually irradiate pattern light and develop it to confirm the resolution.
On the contrary, when the resist film in the immersion solvent is irradiated with pattern light and developed to confirm the resolution, the quality of the resolution can be confirmed even though the resolution can be confirmed. It is not possible to distinguish whether it is the influence of the resolution, the influence of the resolution due to the alteration of the resist film, or both.
Regarding the point that the resolution deteriorates due to the alteration of the resist film due to the immersion solvent in (iii), “contact with the immersion solvent between the selective exposure and the post-exposure heating (PEB) over the resist film like a shower, for example. The evaluation test of “inspecting the resolution of the resist pattern obtained by performing the process to be performed, and then developing is sufficient”. Moreover, in this evaluation method, the immersion solvent is directly sprinkled on the resist film, and the immersion conditions become more severe. With regard to this point as well, in the case of a test in which exposure is performed in a completely immersed state, the resolution may be due to the influence of alteration of the immersion solvent, the alteration of the resist composition due to the immersion solvent, or both effects. I don't know if it has changed.
The phenomena (ii) and (iii) are phenomena that are integrated on the front and back sides, and can be grasped by confirming the degree of alteration such as deterioration of pattern shape and sensitivity deterioration due to the immersion solvent of the resist film. Therefore, if only the point (iii) is verified, the verification related to the point (ii) is also included.
Based on such an analysis, the immersion exposure suitability of a resist film formed from a new resist composition suitable for the immersion exposure process is determined as “an immersion solvent between selective exposure and post-exposure heating (PEB), for example, It was confirmed by an evaluation test (hereinafter referred to as “evaluation test 1”) in which a process of contacting the resist film like a shower was performed, followed by development, and the resolution of the obtained resist pattern was inspected.
Furthermore, as another evaluation method that has further advanced the evaluation test 1, a configuration in which an actual manufacturing process is simulated, “the exposure pattern light is substituted with interference light from a prism, and the sample is actually immersed and exposed. The evaluation test (hereinafter referred to as “evaluation test 2”) was also performed and confirmed.
Furthermore, the relationship between the resist film and the immersion solvent was confirmed by “Evaluation Test 3” using the quartz crystal method (quartz balance: film thickness measurement method using Quarts Crystal Microbalance) as a method for measuring extremely small changes in film thickness. did.

  Further, in the present invention, “normal exposure” refers to exposure performed in the state of an inert gas such as air or nitrogen between the lens of the exposure apparatus and the resist layer on the wafer, which is conventionally performed. . “(Meth) acrylic acid” refers to one or both of methacrylic acid and acrylic acid. “Structural unit” refers to a monomer unit constituting a polymer. The “lactone unit” is a group obtained by removing one hydrogen atom from a monocyclic or polycyclic lactone. The “lithography step” usually includes a step of sequentially performing resist coating, pre-baking, selective exposure, heating after exposure, and alkali development, and in some cases includes a post-baking step after the alkali development.

  According to the present invention, there is no surface roughness of the resist pattern, such as a resist pattern having a T-top shape in the immersion lithography process, a sensitivity deterioration is small, and a resist pattern profile shape having a small swelling and excellent accuracy is obtained. Whether or not the resist composition can be evaluated. Therefore, when a resist composition judged to be suitable according to the present invention is used, a resist pattern including an immersion lithography process can be effectively formed.

Hereinafter, the present invention will be described in detail.
[Example of evaluation method (evaluation method by evaluation test 3)]
This evaluation method example (hereinafter referred to as evaluation method 3) is an evaluation method for evaluating whether or not it is suitable as a resist composition used in a resist pattern forming method including a step of immersion exposure,
When the coating film formed using the resist composition is exposed or immersed in water without being exposed, and when the change in the film thickness of the coating film is measured by the quartz vibrator method in the immersed state, it is applied after the exposure. In both the film and the unexposed film, it is judged that it is suitable when the maximum film thickness increase within 10 seconds from the start of measurement of these films is 1.0 nm or less. This is a method for evaluating a resist composition.

  As will be apparent from the evaluation examples, comparative evaluation examples and graphs described later, the resist composition having the maximum film thickness increase of 1.0 nm or less is extremely suitable as a resist composition for immersion exposure process, and is an immersion. It is less susceptible to the adverse effects of the solvent used in the lithography process, and has the effect of being excellent in sensitivity and resist pattern profile shape. The maximum film thickness increase amount is preferably 0.8 nm or less, more preferably 0.5 nm or less, and the closer to 0, the better and more preferable for immersion lithography.

More specifically, the evaluation method 3 will be described according to the measurement procedure of the film thickness value.
The “coating film formed using the resist composition” refers to a coating film obtained by applying a resist composition on a substrate such as a silicon wafer to a predetermined film thickness by a spin coating method or the like, and then drying it. The term “drying” as used herein means that the solvent in the resist composition is heated and volatilized, and is the same as pre-baking in the lithography process. Although the predetermined film thickness is not particularly limited, it was evaluated as 150 nm in the following examples.

Next, the coating film is exposed or immersed in water without being exposed. This is to observe the film thickness variation due to the influence of water in the exposed or unexposed area.
As the light source using a suitable light source to each of the resist, for example, if KrF resist, there a KrF excimer laser (248 nm), if ArF resist, an ArF excimer laser (193 nm), the resist is for _{F 2} For example, an F ₂ excimer laser (157 nm) or the like is used. The amount of exposure in the case of exposure is not particularly limited, but as one index, in a lithography method, a large area that can be visually confirmed is exposed and developed, and the resist film of the large area disappears by development. What is necessary is just to use the minimum exposure amount which can confirm a board | substrate.

Then, a substrate provided with a coating film having the exposed portion and a substrate provided with a coating film having an unexposed portion are each immersed in water, and in the immersed state, a film of each coating film is obtained by a crystal oscillator method. Each change in thickness is measured.
The crystal resonator method is a film thickness measurement method using a known quartz balance (Quarts Crystal Microbalance). By this method, it is possible to measure a slight change in the thickness of the resist film with respect to water in the exposed portion and the unexposed portion in the order of nm. In the present invention, “RDA-QZ3” manufactured by RISOTEC JAPAN was used as the measuring device.

As is clear from comparative evaluation examples described later and graphs showing the results (FIGS. 6 to 8), in the resist that is insufficient as the resist composition for the immersion exposure process, the post-exposure coating film and the unexposed coating film At least one, that is, one or both of these coating films, the maximum film thickness increase amount within 10 seconds from the start of measurement exceeds 1.0 nm.
On the other hand, in both of the above-described coating films, in the resist of the first invention in which the maximum film thickness increase within 10 seconds from the start of measurement is 1.0 nm or less, the finest resist pattern has a 45 nm pattern. It has been confirmed that it is formed.

  The reason for setting 10 seconds from the start of the measurement is that the time required for the actual immersion exposure process is much shorter, and it is sufficient to judge from the behavior within 10 seconds. On the other hand, even if it is judged in a longer time, it is far from the immersion process and becomes a meaningless value.

The maximum increase in film thickness of 1.0 nm or less means that a graph can be drawn when the horizontal axis represents the immersion time and the vertical axis represents the amount of change in film thickness for each of the post-exposure and non-exposure coatings. It is easily understood from the graph. If it demonstrates based on the graph, in the graph of each coating film, the largest film thickness increase amount in both the graphs of those coating films will be calculated | required, and it means that it is 1.0 nm or less.
Further, the film thickness increase amount can be understood from the fact that the above graph is positioned above this with reference to 0, and conversely, the film thickness decrease amount can be understood from being positioned below 0.
From such a graph, the film thickness increase amount or decrease amount of the post-exposure coating film and the unexposed coating film is small, and a graph as horizontal as possible with respect to the time axis is obtained, that is, after 20 seconds, preferably 60 seconds. Even after the lapse, the film thickness increase amount or decrease amount of the post-exposure coating film and the unexposed coating film is more preferably 2 nm or less.
In particular, as is apparent from Evaluation Examples 17 and 18, a resist composition using a ternary polymer containing a (meth) acrylate unit of norbornanelactone or a quaternary polymer containing a (meth) acrylate unit of γ-butyrolactone is preferable. .

[First Aspect and Second Aspect (Evaluation Test 1)]
Hereinafter, the first aspect and the second aspect will be described as examples of the evaluation method of the present invention.
The first aspect of the present invention is an evaluation method for evaluating whether or not it is suitable as a positive resist composition used in a resist pattern forming method including a step of immersion exposure,
The sensitivity when a resist pattern having a 130 nm line-and-space ratio of 1: 1 is formed by a lithography process for normal exposure using a light source with a wavelength of 193 nm, and the lithography process for normal exposure using the same 193 nm light source. In the resist pattern in which the 130 nm line-and-space becomes one-to-one by the simulated immersion lithography process in which the step of bringing the solvent of the immersion exposure into contact with the resist film between the selective exposure and post-exposure heating (PEB) is added The resist composition is characterized in that it is determined that the absolute value of [(X2 / X1) -1] × 100 is 8.0 or less, where X2 is the sensitivity when the film is formed. This is an evaluation method.

The second aspect of the present invention is an evaluation method for evaluating whether or not it is suitable as a negative resist composition used in a resist pattern forming method including a step of immersion exposure,
The sensitivity when a resist pattern with a 160 nm line-and-space ratio of 1: 1 is formed by a lithography process for normal exposure using a light source with a wavelength of 193 nm is X1 ′, while lithography for normal exposure using the same 193 nm light source is used. In the process, a 160-nm line-and-space resist has a one-to-one relationship by a simulated immersion lithography process in which a step of bringing the above immersion exposure solvent into contact with the resist film is added between selective exposure and post-exposure heating (PEB). When the sensitivity at the time of forming a pattern is X2 ′, it is determined that it is preferable when the absolute value of [(X2 ′ / X1 ′) − 1] × 100 is 8.0 or less. This is a method for evaluating a resist composition.
The absolute value defined above is 8.0 or less, preferably 5 or less, and most preferably 3 or less for both positive and negative resist compositions.

  As described in the above “Means for Solving the Problems”, the present inventors, based on the results of Evaluation Test 1, Evaluation Test 2, and Evaluation Test 3, collectively increase the maximum film thickness in Evaluation Method 3. A resist composition having an amount or a suitable absolute value in the first aspect or the second aspect is extremely suitable as a resist composition for an immersion exposure process, and is adversely affected by the solvent used in the immersion lithography process. It has been found that it has the effect of being difficult and having excellent sensitivity and resist pattern profile shape.

The lithography process for normal exposure using a light source with a wavelength of 193 nm in the first aspect or the second aspect is a conventional exposure lens that uses an ArF excimer laser with a wavelength of 193 nm as a light source. By normal exposure that exposes the resist layer on the wafer in the state of inert gas such as air and nitrogen, a normal lithography process on the substrate such as silicon wafer, that is, resist coating, pre-baking, selective exposure, post-exposure heating , And a step of sequentially performing alkali development. In some cases, a post-baking step after the alkali development may be included, and an organic or inorganic antireflection film may be provided between the substrate and the coating layer of the resist composition.
The sensitivity X1 when a resist pattern (hereinafter referred to as “130 nm L & S”) having a one-to-one 130 nm line and space is formed by such a normal exposure lithography process is an exposure amount at which 130 nm L & S is formed. And are frequently used by those skilled in the art and are self-evident.

As a precaution, this sensitivity can be explained by taking the exposure amount on the horizontal axis and the width of the resist line formed by the exposure amount on the vertical axis. obtain.
The equation is given by Y = aLoge (X1) + b, where X1 is the exposure amount, Y is the resist line width, and a and b are constants. Furthermore, if this expression is expanded and changed to an expression representing X1,
X1 = Exp [(Y−b) / a]. If Y = 130 (nm) is introduced into this equation, the ideal sensitivity X1 for calculation is calculated.

The conditions at that time, that is, the number of rotations of resist coating, the pre-bake temperature, the exposure conditions, the post-exposure heating conditions, and the alkali development conditions may be those conventionally used, and are obvious within the range in which 130 nm L & S can be formed. is there. Specifically, the rotational speed is about 2000 rpm, more specifically about 1000 to 4000 rpm, and the pre-baking temperature is in the range of 70 to 140 ° C., thereby forming a resist film thickness of 80 to 250 nm. The exposure condition may be exposure through a mask using an ArF excimer laser exposure apparatus manufactured by Nikon or Canon (NA = 0.60) having a wavelength of 193 nm. A normal binary mask is used as the mask in the selective exposure. As such a mask, a phase shift mask may be used. The post-exposure heating temperature is in the range of 90 to 140 ° C., and the alkali development conditions are 2.38 mass% TMAH (tetramethylammonium hydroxide) developer, developed at 23 ° C. for 15 to 90 seconds, and then Perform a water rinse.
Further, the simulated immersion lithography process in the first aspect or the second aspect refers to a selective exposure and a post-exposure heating in the normal exposure lithography process using the 193 nm ArF excimer laser as a light source as described above. This means a step in which a step of bringing the immersion exposure solvent into contact with the resist film is added during PEB).

Specifically, it is a step of sequentially performing resist coating, pre-baking, selective exposure, a step of bringing a solvent for immersion exposure into contact with the resist film, heating after exposure, and alkali development. In some cases, the post-baking step after the alkali development may be included.
The contact may be performed by immersing the resist film after selective exposure provided on the substrate in a solvent for immersion exposure or spraying it like a shower.
The sensitivity X2 when a 130 nm L & S resist pattern is formed by such a simulated immersion lithography process is the exposure amount at which 130 nm L & S is formed as in the case of X1, and is usually used by those skilled in the art. It is.
Further, the conditions at that time (resist coating rotation speed, pre-baking temperature, exposure conditions, post-exposure heating conditions, alkali development conditions, etc.) are also the same as X1.

In the first aspect, the absolute value of [(X2 / X1) -1] × 100 is required to be 8.0 or less. This absolute value is obtained by calculating X2 and X1 as described above. It's self-evident if it happens. X1 ′ and X2 ′ in the second embodiment are exactly the same as X1 and X2 except that the resist line width is 160 nm. Of course, the same applies to [(X2 ′ / X1 ′) − 1] × 100.
If the absolute value exceeds 8.0, the resist composition is not suitable as a resist composition for immersion exposure process, and problems such as a resist pattern having a T-top shape and a collapse of the resist pattern occur.

Further, when evaluating using a KrF excimer laser with a wavelength of 248 nm, simply changing the exposure wavelength and the line-and-space pattern size as follows, and similarly, the absolute value is 8.0 or less. It has the same effect as the first aspect.
That is, in the case of a KrF excimer laser, it is a positive resist composition used in a resist pattern forming method including a step of immersion exposure, and a 150 nm line and space is obtained by a lithography step of normal exposure using a light source with a wavelength of 248 nm. The sensitivity when forming a one-to-one resist pattern is X1, and in the lithography process of normal exposure using the light source of 248 nm, the immersion exposure is performed between selective exposure and post-exposure heating (PEB). When the sensitivity when a resist pattern having a line-and-space of 1 to 1 is formed by a simulated immersion lithography process including a step of bringing a solvent into contact with a resist film is defined as X2, [(X2 / X1) − The absolute value of 1] × 100 is preferably 8.0 or less. Its absolute value is preferably 5 or less, most preferably 3 or less, and the closer it is to 0, the better.
The resist coating, pre-baking, selective exposure, post-exposure heating, and alkali development in the lithography process are sequentially performed. The resist film thickness when forming the line and space pattern is 300 to 400 nm, and the exposure light is KrF. Except for this, it is the same as the first embodiment.

The positive resist composition and negative resist composition used in the evaluation method are not particularly limited, but include a chemical component containing a resin component whose alkali solubility is changed by the action of an acid and an acid generator component which generates an acid upon exposure. An amplification type is preferred. The chemically amplified resist has hitherto for KrF, for ArF, for F _2, electron beam, but those like various X-ray have been proposed, but is not limited as long as it has a certain range of the absolute value.

  As the resin component, one or two or more kinds of alkali-soluble resins or resins that can be alkali-soluble, which are usually used as base resins for chemically amplified resists, can be used. In the former case, it is a so-called negative type resist composition, and in the latter case, it is a so-called positive type resist composition.

  In the case of the negative type, a crosslinking agent is blended in the resist composition together with the acid generator component. When an acid is generated from the acid generator component by exposure at the time of forming the resist pattern, the acid acts to cause cross-linking between the alkali-soluble resin component and the cross-linking agent, thereby changing to alkali-insoluble. As the alkali-soluble resin, a resin having a unit derived from at least one selected from α- (hydroxyalkyl) acrylic acid or a lower alkyl ester of α- (hydroxyalkyl) acrylic acid is swelled in immersion exposure. Less favorable resist patterns can be formed, which is preferable.

  In addition, as the cross-linking agent, for example, when an amino-based cross-linking agent that is hardly soluble in a solvent for immersion exposure such as glycoluril having a methylol group or an alkoxymethyl group, particularly a butoxymethyl group, is usually used, immersion exposure is performed. Can form a good resist pattern with less swelling. The blending amount of the crosslinking agent is preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the alkali-soluble resin.

In the case of the positive type, the resin component is an alkali-insoluble resin having a so-called acid dissociable dissolution inhibiting group, and when acid is generated from the acid generator component by exposure, the acid dissociates the acid dissociable dissolution inhibiting group. By making it, this resin component becomes alkali-soluble.
In addition, in both cases of the positive type and the negative type, the resin component is a (a0) (a0-1) dicarboxylic acid anhydride-containing structural unit described in detail in a suitable positive resist composition described below and ( a0-2) It is preferable not to have a phenolic hydroxyl group-containing structural unit (hereinafter referred to as (a0) or (a0) unit). By not having this unit, the maximum film thickness increase amount in Evaluation Method 3 can be 1.0 nm or less, and the absolute value in the first and second aspects can be adjusted to 8.0 or less, which is preferable. .

[Positive resist composition]
A preferred positive resist composition is a positive resist composition used in a resist pattern forming method including a step of immersion exposure, having an acid dissociable, dissolution inhibiting group, and increasing alkali solubility by the action of an acid. The resin component (A), an acid generator component (B) that generates an acid upon exposure, an organic solvent (C) that dissolves the component (A) and the component (B), and the component (A) (A1) a structural unit derived from a (meth) acrylic acid ester having an acid dissociable, dissolution inhibiting group, and (a0) (a0-1) a dicarboxylic acid anhydride-containing structural unit or (a0-2) A positive resist composition having no phenolic hydroxyl group-containing structural unit.

In such a positive resist composition, when the acid generated from the component (B) acts, the acid dissociable, dissolution inhibiting group contained in the component (A) is dissociated, thereby the whole component (A). Changes from alkali-insoluble to alkali-soluble.
Therefore, in the formation of the resist pattern, when the positive resist composition applied on the substrate is selectively exposed through the mask pattern, the alkali solubility of the exposed portion is increased and alkali development can be performed.

[Resin component (A)]
In the positive resist composition according to this example, the component (A) includes (a0) (a0-1) dicarboxylic acid anhydride-containing structural unit and (a0-2) phenolic hydroxyl group-containing structural unit (hereinafter referred to as (a0). ) Or (a0) unit)).
In this specification, the (a0-1) acid anhydride-containing structural unit of dicarboxylic acid refers to a structural unit having a —C (O) —O—C (O) — structure. Examples of such include structural units containing monocyclic or polycyclic cyclic acid anhydrides, and more specifically, monocyclic or polycyclic compounds represented by the following [Chemical Formula 1]. Examples thereof include units derived from maleic anhydride and units derived from itaconic acid shown in the following [Chemical Formula 2].

The (a0-2) phenolic hydroxyl group-containing structural unit refers to a structural unit containing a group in which at least one hydroxyl group is bonded to an aromatic hydrocarbon ring such as a benzene ring or a naphthalene ring. As such a thing, a hydroxy styrene unit, ((alpha) -methyl) hydroxy styrene unit, etc. are mentioned, for example.
In the positive resist composition according to this example, the component (A) does not contain (a0), that is, (a0-1) and (a0-2), so that even in the immersion exposure (immersion lithography) process, the sensitivity, A resist pattern having an excellent profile shape can be formed.
It is considered that such a resist composition having (a0) has problems such as alteration of the resist layer in the immersion exposure process, and thus the sensitivity and profile shape deteriorate.

In the positive resist composition according to this example, the component (A) does not have the (a0) unit as described above, and is a structural unit derived from a (meth) acrylic acid ester having an acid dissociable, dissolution inhibiting group. As long as it has (hereinafter referred to as (a1) or (a1) unit), it is not particularly limited.
In terms of improving the properties such as resolution and the like, which are suitable for applications exposed with an ArF excimer laser, the structural unit derived from (meth) acrylic acid ester is 80 mol% or more, preferably 90 mol% or more. (100 mol% is most preferable) It is preferable to contain.
Further, the component (A) is a monomer unit having a plurality of different functions other than the unit (a1) in order to satisfy the resolution, dry etching resistance, and fine pattern shape, for example, Composed of a combination.
A structural unit derived from a (meth) acrylic acid ester having a lactone unit (hereinafter referred to as (a2) or (a2) unit);
A structural unit derived from a (meth) acrylic acid ester having an alcoholic hydroxyl group-containing polycyclic group (hereinafter referred to as (a3) or (a3) unit);
A structural unit comprising a polycyclic group different from any of the acid dissociable, dissolution inhibiting group of the (a1) unit, the lactone unit of the (a2) unit, and the alcoholic hydroxyl group-containing polycyclic group of the (a3) unit ( Hereinafter, (a4) or (a4) unit).

The units (a2), (a3) and / or (a4) can be appropriately combined depending on required characteristics.
Preferably, the component (A) contains the units (a1) and (a2), so that the resistance to solvent used in the immersion lithography process is increased, and the resolution and resist pattern shape are good. It becomes. Furthermore, it is preferable that these two kinds of structural units occupy 40 mol% or more, more preferably 60 mol% or more of the component (A).
Of the units (a1) to (a4), a plurality of different units may be used in combination.

In addition, in the structural unit derived from a (meth) acrylic acid ester such as the above-mentioned (a1) to (a4) units contained in the component (A), a structural unit derived from a methacrylic acid ester and an acrylic acid ester The presence of both derived structural units is preferable from the viewpoint of obtaining a positive resist composition with less surface roughness during etching, less line edge roughness, excellent resolution, and a wide depth of focus.
The surface roughness during etching here is different from the surface roughness of the resist pattern (degradation of profile shape) due to the above-mentioned influence of the solvent and the conventional dry etching resistance. In the resist pattern, the contact hole pattern appears as distortion around the hole pattern, and the line and space pattern appears as line edge roughness.
Line edge roughness occurs in the resist pattern after development. For example, the line edge roughness appears as distortion around the hole in the hole resist pattern, and appears as uneven unevenness on the side surface in the line and space pattern.

In addition, as described above, resolutions of 90 nm, 65 nm, 45 nm, or lower than these are being demanded in the latest state-of-the-art fields. Immersion lithography is expected to improve such resolution. .
Furthermore, it is also desired to widen the depth of focus characteristics.
In the component (A), the structural unit derived from the methacrylic acid ester and the structural unit derived from the ester derived from the acrylate ester are present together as described above to improve these characteristics. Can do.
Further, the defect reduction effect can be obtained by including both of these two structural units. Here, the defect means, for example, a general defect of a scum or a resist pattern which is detected when the surface pattern is observed from directly above the developed resist pattern by a surface defect observation apparatus (trade name “KLA”) manufactured by KLA Tencor. It is.

In this case, the form is not particularly limited as long as the component (A) contains a structural unit derived from a methacrylic acid ester and a structural unit derived from an acrylate ester. For example, the form (A) Ingredients
Copolymer (A1): a copolymer containing a structural unit derived from a methacrylic acid ester and a structural unit derived from an acrylate ester,
May be included,
Mixed resin (A2): a mixed resin of a polymer containing at least a structural unit derived from a methacrylic acid ester and a polymer containing at least a structural unit derived from an acrylate ester,
May be included. One or both of these polymers constituting the mixed resin (A2) may correspond to the copolymer (A1).
Moreover, although other resin components can also be mix | blended with (A) component, what consists of any one or both of the said copolymer (A1) and said mixed resin (A2) is preferable.
Further, in the copolymer (A1) and the mixed resin (A2), two or more different types can be used in combination.

  The structural unit derived from the methacrylic acid ester and the structural unit derived from the acrylate ester in the component (A) are the structural unit derived from the methacrylic acid ester and the structural unit derived from the acrylate ester. 10 to 85 mol%, preferably 20 to 80 mol% of structural units derived from methacrylic acid ester, 15 to 90 mol% of structural units derived from acrylic acid ester, based on the total number of moles of Preferably it is used so that it may become 20-80 mol%.

  If there are too many structural units derived from the methacrylic acid ester, the effect of improving the surface roughness is reduced, and if there are too many structural units derived from the acrylate ester, the resolution may be lowered.

Next, the units (a1) to (a4) will be described in detail.
[(A1) unit]
The unit (a1) is a structural unit derived from a (meth) acrylic acid ester having an acid dissociable, dissolution inhibiting group.
The acid dissociable, dissolution inhibiting group in (a1) has an alkali dissolution inhibiting property that makes the entire component (A) insoluble in alkali before exposure, and is dissociated by the action of an acid generated from the component (B) after exposure. As long as the entire component (A) is changed to alkali-soluble, it can be used without particular limitation. Generally, a group that forms a cyclic or chain tertiary alkyl ester, a tertiary alkoxycarbonyl group, or a chain alkoxyalkyl group is widely known with a carboxyl group of (meth) acrylic acid. .

As the acid dissociable inhibitory group in (a1), for example, an acid dissociable, dissolution inhibiting group containing an aliphatic polycyclic group can be suitably used.
As the polycyclic group, one hydrogen atom is removed from bicycloalkane, tricycloalkane, teracycloalkane, etc., which may or may not be substituted with a fluorine atom or a fluorinated alkyl group. Examples include groups. Specific examples include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Such a polycyclic group can be appropriately selected and used from among many proposed ArF resists. Of these, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are industrially preferable.
Monomer units suitable as (a1) are shown in the following [Chemical Formula 3] to [Chemical Formula 11].

（式中、Ｒは水素原子又はメチル基、Ｒ^１は低級アルキル基である。）

(In the formula, R is a hydrogen atom or a methyl group, and R ¹ is a lower alkyl group.)

（式中、Ｒは水素原子又はメチル基、Ｒ^２及びＲ^３はそれぞれ独立して低級アルキル基である。）

(In the formula, R is a hydrogen atom or a methyl group, and R ² and R ³ are each independently a lower alkyl group.)

（式中、Ｒは水素原子又はメチル基、Ｒ^４は第３級アルキル基である。）

(In the formula, R is a hydrogen atom or a methyl group, and R ⁴ is a tertiary alkyl group.)

（式中、Ｒは水素原子又はメチル基である。）

(In the formula, R is a hydrogen atom or a methyl group.)

（式中、Ｒは水素原子又はメチル基、Ｒ^５はメチル基である。）

(In the formula, R is a hydrogen atom or a methyl group, and R ⁵ is a methyl group.)

（式中、Ｒは水素原子又はメチル基、Ｒ^６は低級アルキル基である。）

(In the formula, R is a hydrogen atom or a methyl group, and R ⁶ is a lower alkyl group.)

（式中、Ｒは水素原子又はメチル基である。）

(In the formula, R is a hydrogen atom or a methyl group.)

（式中、Ｒは水素原子又はメチル基である。）

(In the formula, R is a hydrogen atom or a methyl group.)

（式中、Ｒは水素原子又はメチル基、Ｒ^７は低級アルキル基である。）

(In the formula, R is a hydrogen atom or a methyl group, and R ⁷ is a lower alkyl group.)

Each of R ^{1 to} R ³ and R ^{6 to} R ⁷ is preferably a lower linear or branched alkyl group having 1 to 5 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, Examples thereof include an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Industrially, a methyl group or an ethyl group is preferable.
R ⁴ is a tertiary alkyl group such as a tert-butyl group or a tert-amyl group, and the case where it is a tert-butyl group is industrially preferred.
Among the units listed above as the (a1) unit, the structural units represented by the general formulas (I), (II), and (III) are particularly excellent in solubility resistance to the solvent used in the immersion lithography process, and high It is more preferable because a pattern having excellent resolution can be formed.

[(A2) unit]
Since the unit (a2) has a lactone unit, it is effective for enhancing the adhesion between the resist film and the substrate and increasing the hydrophilicity with the developer, and is resistant to the solvent used in the immersion lithography process. Also excellent.
The unit (a2) may be any unit having a lactone unit and copolymerizable with other structural units of the component (A).
For example, examples of the monocyclic lactone unit include a group in which one hydrogen atom is removed from γ-butyrolactone. Examples of the polycyclic lactone unit include a group obtained by removing one hydrogen atom from a lactone-containing polycycloalkane. At this time, in the lactone unit, the ring containing the —O—C (O) — structure is counted as the first ring. Accordingly, here, when the ring structure is only a ring containing an —O—C (O) — structure, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
Monomer units suitable as (a2) are shown in the following general formulas [Chemical Formula 12] to [Chemical Formula 14].

（式中Ｒは水素原子又はメチル基である）

(Wherein R is a hydrogen atom or a methyl group)

（式中Ｒは水素原子又はメチル基である）

(Wherein R is a hydrogen atom or a methyl group)

（式中Ｒは水素原子又はメチル基である）

(Wherein R is a hydrogen atom or a methyl group)

  Among these, γ-butyrolactone ester of (meth) acrylic acid having an ester bond at the α carbon as shown in [Chemical Formula 14] or norbornane lactone ester such as [Chemical Formula 12] or [Chemical Formula 13] is particularly preferable. It is easy to obtain industrially and is preferable.

[(A3) units]
The unit (a3) is a structural unit derived from a (meth) acrylic acid ester having an alcoholic hydroxyl group-containing polycyclic group.
Since the hydroxyl group in the alcoholic hydroxyl group-containing polycyclic group is a polar group, the use of this increases the hydrophilicity of the entire component (A) with the developer, improves the alkali solubility in the exposed area, and immersion. It also has excellent resistance to dissolution in the solvent used in the lithography process. Therefore, it is preferable that the component (A) has (a3) because the resolution is improved.
And as a polycyclic group in (a3), it can select from the aliphatic polycyclic group similar to what was illustrated in description of the said (a1) suitably, and can be used.
The alcoholic hydroxyl group-containing polycyclic group in (a3) is not particularly limited, but for example, a hydroxyl group-containing adamantyl group is preferably used.
Furthermore, it is preferable that this hydroxyl group-containing adamantyl group is represented by the following general formula (IV) because it has the effect of increasing dry etching resistance and increasing the perpendicularity of the pattern cross-sectional shape.

（式中、ｎは１〜３の整数である。）

(In the formula, n is an integer of 1 to 3.)

The unit (a3) may be any unit as long as it has an alcoholic hydroxyl group-containing polycyclic group as described above and can be copolymerized with other structural units of the component (A).
Specifically, a structural unit represented by the following general formula (V) is preferable.

（式中、Ｒは水素原子またはメチル基である。）

(In the formula, R is a hydrogen atom or a methyl group.)

[(A4) units]
In the unit (a4), the polycyclic group “different from any of the acid dissociable, dissolution inhibiting group, the lactone unit, and the alcoholic hydroxyl group-containing polycyclic group” means that in the component (A), (a4) A polycyclic group in which the unit polycyclic group does not overlap with any of the (a1) unit acid dissociable, dissolution inhibiting group, the (a2) unit lactone unit, and the (a3) unit alcoholic hydroxyl group-containing polycyclic group. (A4) is an acid dissociable, dissolution inhibiting group of unit (a1), a lactone unit of unit (a2), and an alcoholic hydroxyl group of unit (a3) constituting component (A) This means that none of the contained polycyclic groups are retained.

The polycyclic group in the unit (a4) is not particularly limited as long as it is selected so as not to overlap with the structural units used as the units (a1) to (a3) in one component (A). It is not a thing. For example, as the polycyclic group in the (a4) unit, an aliphatic polycyclic group similar to the one exemplified as the (a1) unit can be used, and many conventionally known ArF positive resist materials can be used. Things can be used.
In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, and a tetracyclododecanyl group is preferable in terms of industrial availability.

As the unit (a4), any unit may be used as long as it has a polycyclic group as described above and can be copolymerized with other structural units of the component (A).
Preferred examples of (a4) are shown in the following [Chemical Formula 17] to [Chemical Formula 19].

（式中Ｒは水素原子又はメチル基である）

(Wherein R is a hydrogen atom or a methyl group)

（式中Ｒは水素原子又はメチル基である）

(Wherein R is a hydrogen atom or a methyl group)

（式中Ｒは水素原子又はメチル基である）

(Wherein R is a hydrogen atom or a methyl group)

In the positive resist composition of this example, the composition of the component (A) is such that the unit (a1) is 20 to 60 mol%, preferably 30 to 50, based on the total of the constituent units constituting the component (A). The mol% is preferable because of excellent resolution.
Moreover, it is excellent in the resolution and adhesiveness that the unit (a2) is 20 to 60 mol%, preferably 30 to 50 mol%, based on the total of the structural units constituting the component (A).
Further, when the unit (a3) is used, the resist pattern shape is excellent and preferably 5 to 50 mol%, preferably 10 to 40 mol%, based on the total of the structural units constituting the component (A).
When the unit (a4) is used, the resolution of the semi-dense pattern from the isolated pattern is 1 to 30 mol%, preferably 5 to 20 mol%, based on the total of the structural units constituting the component (A). Excellent and preferable.
Especially, content of each said structural unit (a1)-(a4) in (A) component is (a1) 20-60 mol%, (a2) 20-60 mol%, and (a3) 5-50, respectively. A ternary system that is mol%, or a quaternary system that is (a1) 25-50 mol%, (a2) 25-50 mol%, (a3) 10-30 mol%, and (a4) 3-25 mol% A positive resist composition using a copolymer is preferable because a resist pattern excellent in sensitivity and profile shape can be formed even in an immersion exposure (immersion lithography) process.
In this example, the resin component of the resist for F ₂ excimer laser can also be suitably used as long as it contains the (a1) unit and does not have the (a0) unit. Such a resin component for an F ₂ resist is, for example, a copolymer containing a unit having a group having a fluorine atom or a fluoroalkyl group in the side chain of a (meth) acrylate unit.

In this example, the resin component (A) contains (a1) and, if necessary, monomers corresponding to the respective structural units of (a2), (a3) and / or (a4) as azobisisobutyronitrile (AIBN). It can be easily produced by copolymerization by a known radical polymerization using a radical polymerization initiator such as In addition, by using a chain transfer agent such as HS—CH ₂ —CH ₂ —CH ₂ —C (CF ₃ ) ₂ —OH in combination, —C (CF ₃ ) ₂ —OH at the end of the copolymer. A copolymer having a group introduced therein can also be used.

  Further, the mass average molecular weight (polystyrene equivalent, hereinafter the same) of the resin component (A) in the positive resist composition suitable for the evaluation method 3, the first aspect, and the second aspect is not particularly limited. In the case of negative type, 2000 to 20000, preferably 4000 to 15000, and in the case of positive type, 5000 to 30000, more preferably 8000 to 20000. If it is larger than this range, the solubility in a resist solvent is deteriorated, and if it is smaller, the dry etching resistance and the resist pattern cross-sectional shape may be deteriorated.

  Regarding the resin component (A), a suitable positive resist composition has been described in detail so far, but the resin (A) component can be applied to the evaluation method 3, the first mode, and the second mode. Can be preferably used.

[Acid generator component (B)]
In the resist composition, as the acid generator component (B) to be used, any conventionally known acid generator in chemically amplified resists can be appropriately selected and used.

Among the acid generators, onium salts having a fluorinated alkyl sulfonate ion as an anion are preferable. Examples of preferred acid generators include diphenyliodonium trifluoromethanesulfonate, (4-methoxyphenyl) phenyliodonium trifluoromethanesulfonate, bis (p-tert-butylphenyl) iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, (4 -Methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, (4-methylphenyl) diphenylsulfonium nonafluorobutanesulfonate, (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, (p-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate, diphenyl Iodonium nonafluorobutanesulfonate, (P-tert-butylphenyl) iodonium nonafluorobutanesulfonate, triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium perfluorooctanesulfonate, (4-trifluoromethylphenyl) diphenylsulfonium trifluoromethanesulfonate, (4-trifluoro Examples thereof include onium salts such as methylphenyl) diphenylsulfonium nonafluorobutanesulfonate, tri (p-tert-butylphenyl) sulfonium trifluoromethanesulfonate, tri (p-tert-butylphenyl) sulfonium nonafluorobutanesulfonate.
Among these, a sulfonium salt is preferable, and an onium salt having a fluorinated alkylsulfonic acid ion having 3 or more carbon atoms as an anion is preferable.

As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.
(B) The usage-amount of a component is 0.5-30 mass parts with respect to 100 mass parts of resin components or (A) component, Preferably it is 1-10 mass parts. If the amount is less than 0.5 parts by mass, pattern formation is not sufficiently performed. If the amount exceeds 30 parts by mass, a uniform solution is difficult to obtain, which may cause a decrease in storage stability.

[Organic solvent (C)]
The resist composition is produced by dissolving the resin component or the component (A), the component (B), and any component (D) and / or component (E) described later in an organic solvent (C). be able to.
Any organic solvent (C) may be used as long as it can dissolve the resin component or the component (A) and the component (B) to form a uniform solution, and is conventionally known as a solvent for chemically amplified resists. Any one or two or more of these can be appropriately selected and used.

  Examples of the organic solvent (C) include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, Polypropylene and its derivatives such as dipropylene glycol or monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate, cyclic ethers such as dioxane, lactic acid Methyl, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxypropionic acid Chill, esters such as ethyl ethoxypropionate can be exemplified. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.

In particular, a mixed solvent of propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent having a hydroxy group or lactone such as propylene glycol monomethyl ether (PGME), ethyl lactate (EL), and γ-butyrolactone is a positive resist composition. This is preferable because the storage stability of the product is improved. When EL is mixed with PGMEA, the mass ratio of PGMEA: EL is preferably 6: 4 to 4: 6.
When blending PGME, the mass ratio of PGMEA: PGME is 8: 2 to 2: 8, preferably 8: 2 to 5: 5.

  In the resist composition, the content of the organic solvent (C) is appropriately set according to the resist film thickness so that the solid content concentration of the resist composition is 3 to 30% by mass.

[Other ingredients]
In addition, a nitrogen-containing organic compound can be further added to the resist composition as an optional component (D) in order to improve the resist pattern shape, the stability over time, and the like. A wide variety of nitrogen-containing organic compounds have already been proposed, and any known one may be used, but secondary lower aliphatic amines and tertiary lower aliphatic amines are preferred.
Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms, and examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Tri-n-propylamine, tripentylamine, tridodecylamine, trioctylamine, diethanolamine, triethanolamine, triisopropanol and the like can be mentioned, and alkanolamines such as triethanolamine are particularly preferable.
Moreover, the nitrogen-containing organic compound represented by the following general formula (VI) can also be used preferably.

（式中、Ｒ^１１、Ｒ^１２は、それぞれ独立して低級アルキレン基、Ｒ^１３は低級アルキル基を示す。）

(In the formula, R ¹¹ and R ¹² each independently represent a lower alkylene group, and R ¹³ represents a lower alkyl group.)

R ¹¹ , R ¹² and R ¹³ may be linear, branched or cyclic, but are preferably linear or branched.
R ^11, the carbon number of ^{R 12, R 13,} from the viewpoint of molecular weight control, respectively 1-5, preferably 1-3. The carbon numbers of R ¹¹ , R ¹² and R ¹³ may be the same or different. The structures of R ¹¹ and R ¹² may be the same or different.
Examples of the compound represented by the general formula (VI) include tris- (2-methoxymethoxyethyl) amine, tris-2- (2-methoxy (ethoxy)) ethylamine, and tris- (2- (2-methoxyethoxy). Methoxyethyl) amine and the like. Of these, tris-2- (2-methoxy (ethoxy)) ethylamine is preferable.
Among these nitrogen-containing organic compounds, the compound represented by the general formula (VI) is particularly preferable, and tris-2- (2-methoxy (ethoxy)) ethylamine is particularly dissolved in the solvent used in the immersion lithography process. The property is small and preferable. These may be used alone or in combination of two or more.
These amines are usually used in the range of 0.01 to 2.0% by mass with respect to the resin component or component (A).

In addition, for the purpose of preventing the sensitivity deterioration due to the blending with the component (D) and improving the resist pattern shape, the stability of holding, etc., as an optional component (E), an organic carboxylic acid or an oxo acid of phosphorus or Derivatives thereof can be included. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
(E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of resin components or (A) component.

  The resist composition may further contain miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving coating properties, dissolution inhibitors, plasticizers, stabilizers. Further, a coloring agent, an antihalation agent, and the like can be added and contained as appropriate.

  For producing the resist composition, for example, the components described below may be mixed and stirred by ordinary methods, and may be dispersed and mixed using a disperser such as a dissolver, a homogenizer, or a three roll mill, if necessary. Moreover, after mixing, you may further filter using a mesh, a membrane filter, etc.

[Pattern formation method]
Next, a method for forming a resist pattern using a resist composition judged to be suitable according to the present invention will be described.
This method is a method for forming a resist pattern using a resist composition, and includes a step of immersion exposure.
First, a resist composition judged to be suitable according to the present invention is applied on a substrate such as a silicon wafer with a spinner or the like, and then pre-baked (PAB treatment).
In addition, it can also be set as the 2 layer laminated body which provided the organic type or the inorganic type antireflection film between the board | substrate and the application layer of the resist composition.
Moreover, it can also be set as the 2 layer laminated body which provided the organic type antireflection film on the application layer of a resist composition, and also can be set as the 3 layer laminated body which provided the antireflection film of the lower layer on this.
The steps so far can be performed using a known method. The operating conditions and the like are preferably set as appropriate according to the composition and characteristics of the resist composition to be used.

Next, immersion exposure (Liquid Immersion Lithography) is selectively performed on the resist layer, which is a coating film of the resist composition obtained above, through a desired mask pattern. At this time, the space between the resist layer and the lens at the lowest position of the exposure apparatus is previously filled with a solvent having a refractive index larger than the refractive index of air. It is preferable to perform exposure in a state filled with a solvent having a refractive index smaller than the refractive index of
The wavelength used for exposure is not particularly limited, and using radiation such as ArF excimer laser, KrF excimer laser, F ₂ laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), electron beam, X-ray, soft X-ray, etc. It can be carried out. The resist composition judged to be suitable according to the present invention is effective for a KrF or ArF excimer laser, particularly an ArF excimer laser.

  As described above, in the resist pattern forming method, during exposure, the refractive index between the resist layer and the lens at the lowest position of the exposure apparatus is larger than the refractive index of air and smaller than the refractive index of the resist composition used. It is preferable to fill with a solvent having a refractive index.

Examples of the solvent having a refractive index that is larger than the refractive index of air and smaller than the refractive index of the resist composition to be used include water and a fluorine-based inert liquid. Specific examples of the fluorine-based inert liquid include fluorine-based compounds such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as a main component. And a boiling point of 70 to 180 ° C., more preferably a boiling point of 80 to 160 ° C., such as a liquid or a perfluoroalkyl compound. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.). Among the fluorine-based inert liquids, those having a boiling point in the above range are preferable because the immersion liquid can be removed after the exposure by a simple method.
The resist composition judged to be suitable according to the present invention is not particularly susceptible to adverse effects on water, and is excellent in sensitivity and resist pattern profile shape. Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.
Further, the refractive index of the solvent having a refractive index larger than that of air and smaller than that of the resist composition used is not particularly limited as long as it is within the above range.

Next, after the exposure process is completed, PEB (post-exposure heating) is performed, and subsequently, development processing is performed using an alkaline developer composed of an alkaline aqueous solution. And preferably, water rinsing is performed using pure water. In the water rinse, for example, water is dropped or sprayed on the surface of the substrate while rotating the substrate to wash away the developer on the substrate and the resist composition dissolved by the developer. And the resist pattern by which the coating film of the resist composition was patterned by the shape according to the mask pattern by drying is obtained.
By forming the resist pattern in this manner, a resist pattern with a fine line width, particularly a line and space (L & S) pattern with a small pitch can be manufactured with good resolution.
Here, the pitch in the line and space pattern refers to the total distance of the resist pattern width and the space width in the line width direction of the pattern.

In Evaluation Method 3, when the maximum film thickness increase amount is 1.0 nm or less, the resist composition has a refractive index that is larger than the refractive index of the air and smaller than the refractive index of the resist composition used. The resist pattern has a T-top shape, even when it comes into contact with a solvent having a high rate, so that the resist pattern surface is not rough, the sensitivity deterioration is small, the swelling is small, and the resist pattern profile shape is highly accurate. Can be evaluated.
In addition, the positive or negative resist composition according to the first and second aspects has an absolute value of [(X2 / X1) -1] × 100 or [(X2 ′ / X1 ′)-1] × 100. Is 8.0 or less, the resist pattern can be obtained even when the resist composition is in contact with a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist composition used. -It can be evaluated that there is no surface roughness of the resist pattern such as a top shape, sensitivity deterioration is small, swelling is small, and a highly accurate resist pattern excellent in resist pattern profile shape can be obtained.
In addition, since the above preferred positive resist composition contains the resin component (A) having the structural unit (a1) and not having (a0), the resist composition is made of the air. Even if it comes in contact with a solvent having a refractive index larger than the refractive index and smaller than the refractive index of the resist composition to be used, the resist pattern has a T-top shape and the surface of the resist pattern is not rough, and the sensitivity is deteriorated. It is possible to obtain a highly accurate resist pattern that is small in size and small in swelling and excellent in resist pattern profile shape.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.
In the following, “Evaluation Example” indicates that a suitable result is obtained as a resist composition used in a resist pattern forming method including an immersion process, and “Comparative Evaluation” indicates that a suitable result is not obtained. As an example.
[Evaluation Example 1] (Evaluation Test 1)
The following (A) component, (B) component, and (D) component were uniformly dissolved in the (C) component to prepare a positive resist composition 1.
As the component (A), 100 parts by mass of a methacrylic acid ester / acrylic acid ester copolymer composed of the three structural units shown in [Chemical Formula 21] was used. (A) The ratio of each structural unit p, q, r used for preparation of component was p = 50 mol%, q = 30 mol%, and r = 20 mol%. In addition, this copolymer does not have an anhydride-containing structural unit of dicarboxylic acid and a phenolic hydroxyl group-containing structural unit. The prepared component (A) had a mass average molecular weight of 10,000.

As the component (B), 3.5 parts by mass of triphenylsulfonium nonafluorobutanesulfonate and 1.0 part by mass of (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate were used.
As the component (C), a mixed solvent of 1900 parts by mass (mass ratio 6: 4) of a mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.
As component (D), 0.3 parts by mass of triethanolamine was used.

Next, a resist pattern was formed using the resist composition 1 obtained above.
First, an organic antireflection film composition “AR-19” (trade name, manufactured by Shipley) is applied onto a silicon wafer using a spinner, and baked on a hot plate at 215 ° C. for 60 seconds to be dried. Thus, an organic antireflection film having a film thickness of 82 nm was formed. Then, the positive resist composition 1 obtained above is applied onto the antireflection film using a spinner, prebaked on a hot plate at 115 ° C. for 90 seconds, and dried to form an antireflection film on the antireflection film. A resist layer having a thickness of 150 nm was formed.
Next, selective irradiation is performed using an ArF excimer laser (193 nm) with an exposure apparatus NSR-S302B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.60, σ = 0.75) through a mask pattern. did. Then, as a simulated immersion exposure treatment, pure water was continuously dropped at 23 ° C. for 5 minutes while rotating the silicon wafer provided with the resist layer after the exposure.
Next, PEB treatment was performed at 115 ° C. for 90 seconds, and further developed at 23 ° C. with an alkali developer for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

The thus obtained resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined.
In the resist composition 1 of this evaluation example, Eop was 12.7 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, using the resist composition 1 of this evaluation example, the above-described simulated immersion exposure treatment is not performed, and the conventional lithography process of normal exposure, that is, the simulated immersion exposure treatment is not performed. When the resist pattern was formed by this method, Eop was 12.4 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 2.4. When the sensitivity ratio of the simulated immersion exposure treatment to the sensitivity of normal exposure was determined (12.7 / 12.4), it was 1.02. Moreover, the resist pattern was not T-top shape and surface roughness was not seen, and it was favorable.

[Evaluation Example 2] (Evaluation Test 1)
The following component (A), component (B), component (D) and other components were uniformly dissolved in component (C) to prepare positive resist composition 2.
As the component (A), 100 parts by mass of a methacrylic acid ester copolymer composed of the three structural units shown in [Chemical Formula 22] was used. (A) Ratio of each structural unit p, q, and r used for preparation of component was p = 40 mol%, q = 40 mol%, and r = 20 mol%. In addition, this copolymer does not have an anhydride-containing structural unit of dicarboxylic acid and a phenolic hydroxyl group-containing structural unit. The prepared component (A) had a mass average molecular weight of 10,000.

As the component (B), 2.0 parts by mass of (4-methylphenyl) diphenylsulfonium nonafluorobutanesulfonate and 0.8 parts by mass of tri (p-tert-butylphenyl) sulfonium trifluoromethanesulfonate were used.
As the component (C), a mixed solvent of 700 parts by mass (mass ratio 6: 4) of a mixed solvent of propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether was used.
As component (D), 0.3 parts by mass of triethanolamine was used.
Moreover, 25 mass parts of (gamma) -butyrolactone was used as another component.

Using the positive resist composition 2 produced as described above, pattern formation including a simulated immersion exposure treatment was performed in the same manner as in Evaluation Example 1. At that time, a resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined. The Eop was determined to be 20.3 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, using the resist composition 2 of this evaluation example, the simulated immersion exposure process is not performed, and the conventional lithography process of normal exposure, that is, the simulated immersion exposure process is not performed. When the resist pattern was formed by this method, Eop was 20.1 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 1.0. When the sensitivity ratio of the simulated immersion exposure processing to the sensitivity of normal exposure was determined (20.3 / 20.1), it was 1.01. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.

[Comparative Evaluation Example 1] (Evaluation Test 1)
The following (A) component, (B) component, and (D) component were uniformly dissolved in the (C) component to prepare a positive resist composition 10.
As the component (A), 100 parts by mass of a polymer composed of the structural unit shown in [Chemical Formula 23] was used. The prepared component (A) had a mass average molecular weight of 10,000.

As the component (B), 3.5 parts by mass of triphenylsulfonium nonafluorobutanesulfonate and 1.0 part by mass of (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate were used.
As the component (C), a mixed solvent (mass ratio 6: 4) of 1900 parts by mass of a mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.
As component (D), 0.3 parts by mass of triethanolamine was used.

Using the positive resist composition 10 produced as described above, pattern formation including a simulated immersion exposure treatment was performed in the same manner as in Evaluation Example 1. At that time, a resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined. The Eop was determined to be 9.1 mJ / cm ² . This is X2. Moreover, although the resist pattern was not T-top shape, surface roughness was observed and it was inferior.
On the other hand, using the resist composition 10 of the comparative evaluation example 1, the simulated immersion exposure treatment is not performed, and the conventional lithography process of normal exposure, that is, the simulated immersion exposure treatment is not performed. When a resist pattern was formed by the same method, Eop was 8.4 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 8.3. When the sensitivity ratio of the simulated immersion exposure treatment to the sensitivity of normal exposure was determined (9.1 / 8.4), it was 1.08. Moreover, although the resist pattern was not T-top shape, surface roughness was observed and it was inferior.

From the results of Evaluation Example 1 and Evaluation Example 2, when the sensitivity (Eth) was compared between the simulated immersion exposure process and the normal exposure process using the resist composition, the absolute values were both 2 or less. It was. That is, these resist compositions exhibit little deterioration in sensitivity even when brought into contact with water, and also have a resolution, no T-top shape, no surface roughness, excellent resist pattern shape, and resists employing immersion lithography. It was found that the resist composition was suitable for pattern formation.
On the other hand, from the results of Comparative Evaluation Example 1, in the resist composition using the resin having an acid anhydride-containing structural unit of dicarboxylic acid, the sensitivity is compared with the case where the simulated immersion exposure treatment and the normal exposure treatment are performed. The value was 8.3, the sensitivity was greatly deteriorated, the surface was roughened, and it was found to be a defective resist pattern and unsuitable for immersion lithography.

[Comparative Evaluation Example 2] (Evaluation Test 1)
The following (A) component, (B) component, and (D) component were uniformly dissolved in the (C) component to prepare a positive resist composition 11.
As the component (A), 100 parts by mass of a copolymer composed of 63 mol% hydroxystyrene units, 24 mol% styrene units and 13 mol% tert-butyl acrylate units was used. The weight average molecular weight of the prepared component (A) was 12,000.
As the component (B), 2.8 parts by mass of bis (tert-butylphenyliodonium trifluoromethanesulfonate) and 1.0 part by mass of dimethylmonophenylsulfonium trifluoromethanesulfonate were used.
As component (C), 600 parts by mass of ethyl lactate was used.
As component (D), 0.26 parts by mass of triethanolamine was used, and as component (E), 0.28 parts by mass of phenylphosphonic acid was used.

A resist pattern was formed using the positive resist composition 11 produced as described above.
First, an organic antireflection film composition “AR-3” (trade name, manufactured by Shipley) is applied onto a silicon wafer using a spinner, and is baked and dried on a hot plate at 220 ° C. for 60 seconds. Thus, an organic antireflection film having a thickness of 62 nm was formed. Then, the positive resist composition 11 obtained above is applied on the antireflection film using a spinner, pre-baked on a hot plate at 110 ° C. for 90 seconds, and dried to form an antireflection film. A resist layer having a thickness of 280 nm was formed.
Next, selective irradiation was performed using a KrF excimer laser (248 nm) with an exposure apparatus NSR-S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.60) through a mask pattern.
Then, as a simulated immersion exposure treatment, pure water was continuously dropped at 23 ° C. for 5 minutes while rotating the silicon wafer provided with the resist layer after the exposure.
Next, PEB treatment was performed at 110 ° C. for 90 seconds, and further developed at 23 ° C. with an alkali developer for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

The thus obtained resist pattern with a 140 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined.
As a result, Eop was 22.0 mJ / cm ² . This is X2. The resist pattern was T-top shaped and surface roughness was observed.
On the other hand, using the resist composition 11 of this comparative evaluation example, the simulated immersion exposure process is not performed, and the conventional lithography process, ie, the simulated immersion exposure process is not performed. When a resist pattern was formed by such a method, Eop was 20.0 mJ / cm ² . This is X2.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 10. When the sensitivity ratio of the simulated immersion exposure processing to the sensitivity of normal exposure was determined (22.0 / 20.0), it was 1.1. Moreover, the resist pattern was not T-top shape and surface roughness was not seen, and it was favorable.

[Comparative Evaluation Example 3] (Evaluation Test 1)
The following component (A), component (B), and component (D) were uniformly dissolved in component (C) to prepare positive resist composition 12.
As the component (A), as the component, 64 mol% of hydroxystyrene units, 70 parts by mass of a copolymer composed of 36 mol% of 1-ethoxy-1-ethyloxystyrene units, 67 mol% of hydroxystyrene units, tetrahydropyranyloxystyrene A mixed resin of 30 parts by mass of a copolymer composed of 33 mol% structural units was used. The prepared component (A) had a weight average molecular weight of 8,000.
As the component (B), 4 parts by mass of bis (cyclohexylsulfonyl) diazomethane and 1 part by mass of tert-butylphenyliodonium trifluoromethanesulfonate were used.
As the component (C), a mixed solvent (mass ratio 6: 4) of 600 parts by mass of a mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.
As component (D), 0.52 parts by mass of triisopropanolamine was used, and as component (E), 0.54 parts by mass of dodecanoic acid was used.

A resist pattern was formed using the positive resist composition 12 produced as described above.
First, an organic antireflection film composition “DUV-44” (trade name, manufactured by Brewer Science Co., Ltd.) is applied onto a silicon wafer using a spinner, and baked on a hot plate at 225 ° C. for 90 seconds to be dried. Thereby, an organic antireflection film having a film thickness of 65 nm was formed. Then, the positive resist composition obtained above is applied onto the antireflection film using a spinner, prebaked on a hot plate at 90 ° C. for 90 seconds, and dried to obtain a film thickness on the antireflection film. A 280 nm resist layer was formed.
Next, selective irradiation was performed using a KrF excimer laser (248 nm) with an exposure apparatus NSR-S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.60) through a mask pattern.
Then, as a simulated immersion exposure treatment, pure water was continuously dropped at 23 ° C. for 5 minutes while rotating the silicon wafer provided with the resist layer after the exposure.
Next, PEB treatment was performed at 110 ° C. for 90 seconds, and further developed at 23 ° C. with an alkali developer for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

The thus obtained resist pattern with a 140 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined.
As a result, Eop was 26.3 mJ / cm ² . This is X2. Moreover, although the resist pattern was not T-top shape, surface roughness was seen.
On the other hand, using the resist composition 12 of this comparative evaluation example, the simulation immersion exposure process is not performed, and the conventional lithography process of normal exposure, that is, the simulation immersion exposure process is not performed. When a resist pattern was formed by such a method, Eop was 16.8 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 56.5. When the sensitivity ratio of the simulated immersion exposure processing with respect to the sensitivity of normal exposure was obtained (26.3 / 16.8), it was 1.57. Moreover, the resist pattern was not T-top shape and surface roughness was not seen, and it was favorable.

From the results of Comparative Evaluation Examples 2 and 3, it is resist pattern formation using KrF excimer laser instead of ArF excimer laser, but in the resist composition using resin having a phenolic hydroxyl group-containing structural unit, simulated immersion exposure When Eop is compared with processing and normal exposure, the absolute value is 10,56.5, the sensitivity is greatly deteriorated, and at the same time, T-top shape and surface roughness are seen in the resist pattern, which is completely unsuitable for immersion lithography. It has been found.
In addition, “UVII-HS”, which is tested in Non-Patent Document 1 listed in the prior art, is a resin having a phenolic hydroxyl group as in the positive resist compositions 11 and 12 used in Comparative Evaluation Examples 2 and 3 above. The points they have in common.
In Evaluation Examples 1 and 2 and Comparative Evaluation Examples 1 to 3, the evaluation test 1 is performed, and the actual immersion exposure (immersion lithography) is not performed by the simulated immersion exposure process in which water is dropped. However, in this evaluation test 1, pure water is continuously dripped at 23 ° C. for 5 minutes while rotating the silicon wafer, and the conditions are more severe than in the immersion state. If there is no problem in the pattern shape, it is obvious that when immersion lithography is applied, the effects of improved resolution and wide depth of focus can be realized.

[Evaluation Example 3, Comparative Evaluation Example 4] (Evaluation Test 2)
The above “AR-19” was formed on the substrate (silico wafer) in the same manner as in Evaluation Example 1 except that the resist film thickness was changed to 140 nm using the resist composition 1 having the same composition as in Evaluation Example 1. 82 nm was provided, and a resist layer was formed thereon.
Then, as an evaluation test 2, immersion exposure was performed by using an experimental apparatus manufactured by Nikon Corporation and performing an experiment (two-beam interference experiment) using a prism, water, and two beam interferences of 193 nm. A similar method is also disclosed in Non-Patent Document 2 and is known as a method for easily obtaining an L & S pattern at a laboratory level.

In immersion exposure in Evaluation Example 3, an aqueous solvent layer was formed as an immersion solvent between the resist layer and the prism lower surface.
In addition, the exposure amount from which the L & S pattern was stably obtained was selected as the exposure amount. Further, after forming a resist film on the antireflection film, after about 1 hour has passed, exposure treatment (PCD: post-coating delay), and after further exposure, at least 30 minutes have passed and then post-exposure heating (PED: post exposure delay).
On the other hand, in Comparative Evaluation Example 4, the experiment was conducted in the same manner as in Evaluation Example 3 except that the prism was directly brought into contact with the resist layer without using the aqueous solvent as the immersion solvent.
Development was carried out in the same manner as in Evaluation Example 1.
The evaluation test 2 examines the influence of the aqueous solvent layer on the resist layer, the resolution of the resist pattern, and the pattern profile. Therefore, if a result equivalent to that in Comparative Evaluation Example 4 using air is obtained, the resist layer can be resolved without being affected by the solvent layer, and if used in immersion lithography, the resolution is high. A wider depth of focus is achieved, and a finer pattern can be obtained.

  The results are shown in Table 1.

As is apparent from the results in Table 1, in Evaluation Example 3, the same resist composition 1 as in Evaluation Example 1 is used. Such a resist composition targets a line width of 90 nm and a pitch of 180 nm, and is pure. When water was used, the same results were obtained with respect to the comparative evaluation example 4 using air and the line width and pitch.
When the target was a line width of 65 nm and a pitch of 130 nm, a comparative experiment using air as a medium was not performed, but even when pure water was used, a value close to the target was obtained, and the influence of the solvent was reduced. It was found that resolution was possible without receiving it.
Moreover, the profile shape was favorable in all. Further, with respect to LER (line edge roughness), when pure water was used, an excellent result with a small roughness was obtained as compared with Comparative Evaluation Example 4 using air.
Further, in this two-beam interference experiment, the environment for managing contamination such as amine is insufficient compared to a clean room in which normal resist patterning evaluation is performed. Even in such an environment, about 1 hour is required. Such good results were also obtained with PCD and PED treatment for at least 30 minutes.
Therefore, it has been clarified that when this resist composition is applied to immersion lithography, it can be sufficiently resolved up to, for example, a line width of 50 nm and a pitch of about 100 nm.

[Comparative Evaluation Examples 5 and 6] (Evaluation Test 2)
Using the resist composition 10 having the same composition as in Comparative Evaluation Example 1 and changing the resist film thickness to 140 nm, the above “AR-19” was formed on the substrate (silico wafer) in the same manner as in Comparative Evaluation Example 1. ”Was provided at 82 nm, and a resist layer was formed thereon.
Then, as in Evaluation Example 3, as an evaluation test 2, immersion exposure was performed using a prism, water, and two light flux interferences of 193 nm using an experimental apparatus created by Nikon.
In immersion exposure in this comparative evaluation example, an aqueous solvent layer was formed as an immersion solvent between the resist layer and the prism lower surface in the same manner as in Evaluation Example 3.
In addition, the exposure amount from which the L & S pattern was stably obtained was selected as the exposure amount.
On the other hand, in Comparative Evaluation Example 6, the experiment was performed in the same manner as Comparative Evaluation Example 5 except that the water solvent as the immersion solvent was not used and the prism and the resist layer were directly brought into contact with each other.
Development was performed in the same manner as Comparative Evaluation Example 1.

  The results are shown in Table 2.

  From the results of Comparative Evaluation Examples 5 and 6 and Comparative Evaluation Example 1 and Evaluation Examples 1 and 2, Evaluation Example 3 and Comparative Evaluation Example 4, the absolute value obtained from the formula [(X2 / X1) -1] × 100 If it is 8.0 or less, it is clear that a good resist pattern can be obtained even in immersion exposure, and if the numerical value is exceeded, no resist pattern is formed in immersion exposure.

[Evaluation Example 4] (Evaluation Test 2)
The following chemical formula

(Wherein m: n is 84:16 (mol%)) and a poorly water-soluble crosslink consisting of 10% by mass of tetrabutoxymethylated glycoluril with respect to this resin component. An acid generator composed of 1% by mass of triphenylsulfonium nonafluorobutane sulfonate and an amine component composed of 0.6% by mass of 4-phenylpyridine are dissolved in propylene glycol monomethyl ether, and the solid content mass is determined. A negative resist composition having a content of 8.1% by mass was prepared.
On the other hand, an organic antireflection film “AR-19” (trade name, manufactured by Shipley) is applied onto a silicon wafer using a spinner, and baked on a hot plate at 215 ° C. for 60 seconds to be dried. Thus, an organic antireflection film having a film thickness of 82 nm was formed. On the antireflection film, the negative resist composition is applied using a spinner, prebaked at 110 ° C. for 60 seconds and dried to form a resist film having a thickness of 250 nm on the antireflection film. did.
Similar to Evaluation Example 3 and Comparative Evaluation Example 5 on the substrate, “two-beam interference exposure apparatus that simulates pattern exposure light by irradiating two-beam interference light through a prism (manufactured by Nikon Corporation) Immersion test (Evaluation Test 2) was performed using pure water as the immersion solvent and an ArF excimer laser with a wavelength of 193 nm as the light source. Note that the lower surface of the prism of the apparatus used was in contact with the resist film through pure water.
After the exposure, PEB treatment was performed at 110 ° C. for 60 seconds, and further developed at 23 ° C. with an alkali developer for 40 seconds. A 2.38 wt% tetramethylammonium hydroxide aqueous solution was used as the alkaline developer.
When the resist pattern having a 90 nm line and space of 1: 1 obtained in this way was observed with a scanning electron microscope (SEM), the profile of this pattern was good with small surface roughness and swelling. .

[Evaluation Example 5] (Evaluation Test 1)
In Evaluation Example 4, pattern formation including not the immersion exposure (Evaluation Test 2) but a simulated immersion exposure process similar to that in Evaluation Example 1 was performed.
Specifically, first, an organic antireflection film composition “AR-19” (trade name, manufactured by Shipley) was applied onto a silicon wafer using a spinner, and baked on a hot plate at 215 ° C. for 60 seconds. By drying, an organic antireflection film having a film thickness of 82 nm was formed. Then, the negative resist composition used in Evaluation Example 4 was applied onto the antireflection film using a spinner, prebaked on a hot plate at 110 ° C. for 60 seconds, and dried to form an antireflection film. A resist layer having a thickness of 300 nm was formed.
Next, an ArF excimer laser (193 nm) is released through the mask pattern using an exposure apparatus NSR-S302B (Nikon Corporation, NA (numerical aperture) = 0.60, 2/3 annular zone) to release the phase shift mask. Was selectively irradiated. Then, as a simulated immersion exposure treatment, pure water was continuously dropped at 23 ° C. for 2 minutes while rotating the silicon wafer provided with the resist layer after the exposure.
Next, PEB treatment was performed at 110 ° C. for 60 seconds, and further developed at 23 ° C. with an alkali developer for 30 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

The resist pattern having a 160 nm line and space ratio of 1: 1 thus obtained was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined.
In the negative resist composition of this evaluation example, Eop was 30.7 mJ / cm ² . This is assumed to be X2 ′. Further, the resist pattern was satisfactory with neither surface roughness nor swelling.
On the other hand, the negative resist composition of this evaluation example is used, except that the simulated immersion exposure treatment is not performed, and the conventional normal exposure lithography process, that is, the simulated immersion exposure treatment is not performed. When a resist pattern was formed by such a method, Eop was 30.1 mJ / cm ² . This is X1 ′.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 '/ X1')-1] * 100, it was 2. When the sensitivity ratio of the simulated immersion exposure treatment to the sensitivity of normal exposure was determined (30.7 / 30.1), it was 1.02. Further, in the profile of this pattern, neither surface roughness nor swelling was observed.

  From the evaluation examples 4 and 5, the negative resist composition also has an absolute value of 2. When such a numerical value of 8.0 or less is taken, the result of the evaluation test 2 of the evaluation example 4 shows that the immersion exposure. Thus, it was confirmed that a good resist pattern can be formed.

[Evaluation Example 6 (Target Resolution 60 nm and 55 nm)] (Evaluation Test 2)
Resist composition 1 of Evaluation Example 1 except that the component (D) was changed from triethanolamine to 0.65 parts by mass of tris-2- (2-methoxy (ethoxy)) ethylamine. (1) In the same manner as in Evaluation Example 1 except that the resist film thickness was further changed to 140 nm, 82 nm of the above “AR-19” was provided on the substrate (silico wafer), and the resist layer was formed thereon. Formed.
Then, an evaluation test 2 (experimental immersion exposure using prism, water, and two light flux interferences of 193 nm using an experimental apparatus made by Nikon) similar to evaluation example 3 was performed. Similar to immersion exposure in Evaluation Example 3, an aqueous solvent layer was formed as an immersion solvent between the resist layer and the prism lower surface.
In addition, the exposure amount from which the L & S pattern was stably obtained was selected as the exposure amount. Development was carried out in the same manner as in Evaluation Example 1. The results are shown in Table 3.

[Evaluation Example 7 (Target Resolution 50 nm and 45 nm)] (Evaluation Test 2)
Substrate (silico wafer) provided with “AR-19” having a thickness of 82 nm in the same manner as in Evaluation example 6, except that the pre-baking temperature was changed to 125 ° C. and the resist film thickness was changed to 110 nm. A resist layer was formed thereon. And after performing the evaluation test 2 similar to the evaluation example 6, it carried out similarly to the evaluation example 6, and formed the resist pattern. The results are shown in Table 3.

[Evaluation Example 8 (Target Resolution 60 nm and 55 nm)] (Evaluation Test 2)
In the resist composition 1 of Evaluation Example 1, the component (B) was changed from a mixture of triphenylsulfonium nonafluorobutanesulfonate and (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate to 5.0 parts by mass of triphenylsulfonium perfluorooctanesulfonate. The same resist composition 1- (2) was used except that the resist film thickness was changed to 1, and the AR film thickness of 82 nm was provided in the same manner as in Evaluation Example 6 except that the resist film thickness was further changed to 140 nm. A resist layer was formed on the substrate (silico wafer). And after performing the evaluation test 2 similar to the evaluation example 6, it carried out similarly to the evaluation example 6, and formed the resist pattern. The results are shown in Table 3.

[Evaluation Example 9 (Target Resolution 50 nm and 45 nm)] (Evaluation Test 2)
Substrate (silico wafer) provided with “AR-19” having a thickness of 82 nm in the same manner as in Evaluation example 6 except that the pre-baking temperature was changed to 125 ° C. and the resist film thickness was changed to 110 nm. A resist layer was formed on the substrate. And after performing the evaluation test 2 similar to the evaluation example 6, it carried out similarly to the evaluation example 6, and formed the resist pattern. The results are shown in Table 3.

  As is clear from the results in Table 3, it is clear that the resist composition judged to be suitable according to the present invention can be sufficiently resolved to a target line width of 45 nm and a pitch of 90 nm by applying it to immersion lithography. It was.

[Evaluation Example 10] (Evaluation Test 1)
The following component (A), component (B), and component (D) were uniformly dissolved in component (C) to prepare positive resist composition 3.
As the component (A), 100 parts by mass of a methacrylic acid ester copolymer composed of the four structural units shown in [Chemical Formula 25] was used. (A) The ratio of each structural unit p, q, r, and t used for preparation of component was p = 40 mol%, q = 40 mol%, r = 15 mol%, and t = 5 mol%. In addition, this copolymer does not have an anhydride-containing structural unit of dicarboxylic acid and a phenolic hydroxyl group-containing structural unit. The prepared component (A) had a mass average molecular weight of 10,000.

As component (B), 5.0 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used.
As the component (C), a mixed solvent of 1900 parts by mass (mass ratio 6: 4) of a mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.
As component (D), 0.3 parts by mass of triethanolamine was used.

Next, a resist pattern was formed in the same manner as in Evaluation Example 1 using the positive resist composition 3 obtained above.
That is, first, an organic antireflection film having a film thickness of 82 nm was formed in the same manner as in Evaluation Example 1 using an organic antireflection film composition “AR-19” (trade name, manufactured by Shipley). Then, using the positive resist composition 3 obtained above, a resist layer having a thickness of 150 nm was formed on the antireflection film by pre-baking similar to that in Evaluation Example 1.
Next, selective irradiation is performed using an ArF excimer laser (193 nm) with an exposure apparatus NSR-S302B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.60, σ = 0.75) through a mask pattern. did. Then, as a simulated immersion exposure treatment, pure water was continuously dropped at 23 ° C. for 2 minutes while rotating the silicon wafer provided with the resist layer after the exposure. In addition, in the evaluation example 1, although it continued dripping for 5 minutes, since it became clear that there was no time dependence in 2 minutes or 5 minutes, it was set as 2 minutes for efficiency.
Next, PEB treatment was performed at 115 ° C. for 90 seconds, and further developed at 23 ° C. with an alkali developer for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

The thus obtained resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined.
In the resist composition 3 of this evaluation example, Eop was 14.32 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, using the resist composition 3 of this evaluation example, the simulated immersion exposure process is not performed, and the conventional lithography process of normal exposure, that is, the simulated immersion exposure process is not performed. When the resist pattern was formed by this method, Eop was 14.37 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 0.3. When the sensitivity ratio of the simulated immersion exposure processing to the sensitivity of normal exposure was determined (14.32 / 14.37), it was 0.997. Moreover, the resist pattern was not T-top shape and surface roughness was not seen, and it was favorable.

[Evaluation Example 11] (Evaluation Test 1)
In the positive resist composition 3 of Evaluation Example 10, except that the component (D) was changed from triethanolamine to 0.46 parts by mass of tripentylamine, the positive resist composition 3- (1) was prepared in the same manner. Prepared.
Using positive resist composition 3- (1) produced as described above, pattern formation including simulated immersion exposure treatment was performed in the same manner as in Evaluation Example 10. At that time, a resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined. The Eop was determined to be 12.79 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, using the positive resist composition 3- (1) of this evaluation example, the above-described simulated immersion exposure treatment is not performed, and the conventional normal exposure lithography process, that is, the simulated immersion exposure treatment is performed. Except for the above, when a resist pattern was formed by the same method, Eop was 12.91 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 0.9. When the sensitivity ratio of the simulated immersion exposure treatment to the sensitivity of normal exposure was determined (12.79 / 12.91), it was 0.991. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.

[Evaluation Example 12] (Evaluation Test 1)
In the same manner as in the positive resist composition 3 of Evaluation Example 10, except that the component (D) was changed from triethanolamine to 1.05 parts by mass of tridodecylamine, positive resist composition 3- (2) was obtained. Prepared.
Using the positive resist composition 3- (2) produced as described above, pattern formation including simulated immersion exposure treatment was performed in the same manner as in Evaluation Example 10. At that time, a resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined. The Eop was determined to be 13.81 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, by using the positive resist composition 3- (2) of this evaluation example, the above-described simulated immersion exposure treatment is not performed, and the conventional normal exposure lithography process, that is, the simulated immersion exposure treatment is performed. When the resist pattern was formed by the same method except for the above, Eop was 13.93 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 0.86. When the sensitivity ratio of the simulated immersion exposure processing to the sensitivity of normal exposure was determined (13.81 / 13.93), it was 0.991. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.

[Evaluation Example 13] (Evaluation Test 1)
In the positive resist composition 1 of Evaluation Example 1, the component (B) is obtained from a mixture of triphenylsulfonimnonafluorobutanesulfonate and (4-methylphenyl) diphenylsulfonium trifluoromethanesulfonate, and tri (p-tert-butylphenyl) sulfonium. A positive resist composition 1- (3) was prepared in the same manner except that the amount was changed to 6.5 parts by mass of nonafluorobutanesulfonate.
Using positive resist composition 1- (3) produced as described above, pattern formation including simulated immersion exposure treatment was performed in the same manner as in Evaluation Example 10. At that time, a resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined. The Eop was determined to be 22.18 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, using the positive resist composition 1- (3) of this evaluation example, the above-described simulated immersion exposure treatment is not performed, and the conventional normal exposure lithography process, that is, the simulated immersion exposure treatment is performed. Except for the above, when a resist pattern was formed by the same method, Eop was 22.56 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 1.68. When the sensitivity ratio of the simulated immersion exposure processing to the sensitivity of normal exposure was determined (22.18 / 22.56), it was 0.983. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.

  From the results of Evaluation Examples 10 to 12, it was found that even when a quaternary copolymer is used, it is also suitable for an immersion lithography process. Further, it was found from Evaluation Examples 1 and 13 that different acid generators are also suitable for the immersion lithography process.

[Evaluation Example 14] (Evaluation Test 3)
The positive resist composition 1- (2) in Evaluation Example 8 was spin-coated on a silicon wafer and heated at 115 ° C. for 90 seconds to provide a resist coating film having a thickness of 150 nm. This is called an unexposed film.
On the other hand, the resist film can be visually confirmed using an ArF excimer laser (193 nm) with an exposure apparatus NSR-S302B (Nikon Corporation, NA (numerical aperture) = 0.60, σ = 0.75). A large area (about 10 mm ² ) region was exposed. The exposure amount was 6 mJ / cm ² . Next, PEB treatment was performed at 115 ° C. for 90 seconds. This is called an exposed coating film.

  Next, the unexposed coating film and the exposed coating film are immersed in ion-exchanged pure water, and in the immersed state, a film thickness measuring device using a quartz balance (hereinafter referred to as QCM) manufactured by RISOTEC JAPAN Co., Ltd. With "RDA-QZ3", the maximum measurement time was 300 seconds, and the change in film thickness of both coating films was measured.

In addition, the frequency fluctuation of the quartz substrate was measured, and the obtained data was processed with the attached analysis software to obtain a graph of the film thickness value with respect to the immersion time. This graph in this evaluation example is graph-1 (see FIG. 1).
In addition, in order to clarify the difference in film thickness variation between exposed and unexposed in the sample, each graph is expressed by the difference from the film thickness value at that time, based on the immersion time of 0 seconds, and plotted on the graph again did. That is, a negative value is shown when the thickness is smaller than the initial film thickness, and a positive value is shown when the thickness is thicker. The maximum value indicated in the positive direction and the maximum value indicated in the negative direction of the film thickness fluctuation value were determined for each sample. When there was no positive or negative behavior, the value was set to 0 nm.
The maximum film thickness increase within 10 seconds from the start of measurement is 0 nm for both the unexposed film and the exposed film, and the maximum film thickness decrease within 10 seconds is 1.16 nm for the unexposed film. It was 0.66 nm in the coating film.

[Evaluation Example 15] (Evaluation Test 3)
A positive resist composition 1- (4) was prepared in the same manner as in the positive resist composition 1- (2), except that triethanolamine was changed to 0.46 parts by mass of tripentylamine.
Subsequently, the change of the film thickness of an unexposed coating film and an exposed coating film was measured by QCM like the evaluation example 14, and the graph of the film thickness value with respect to the same immersion time was obtained. This graph in this evaluation example is referred to as graph-2 (see FIG. 2).
Further, when the maximum film thickness increase within 10 seconds from the start of measurement was obtained in the same manner as in Evaluation Example 14, the unexposed film and the exposed film were both 0 nm and the maximum film thickness decrease within 10 seconds. The amount was 1.00 nm for the unexposed film and 0.52 nm for the exposed film.

[Evaluation Example 16] (Evaluation Test 3)
A positive resist composition 1- (5) was prepared in the same manner as in the positive resist composition 1- (2) except that triethanolamine was changed to 0.71 part by mass of trioctylamine.
Subsequently, the change of the film thickness of an unexposed coating film and an exposed coating film was measured by QCM like the evaluation example 14, and the graph of the film thickness value with respect to the same immersion time was obtained. This graph in this evaluation example is referred to as graph-3 (FIG. 3).
Further, when the maximum film thickness increase within 10 seconds from the start of measurement was obtained in the same manner as in Evaluation Example 14, the unexposed film and the exposed film were both 0 nm and the maximum film thickness decrease within 10 seconds. The amount was 0.81 nm for the unexposed coating and 1.75 nm for the exposed coating.

[Evaluation Example 17] (Evaluation Test 3)
In the positive resist composition 1- (2), the same procedure except that triethanolamine was changed to 0.71 part by mass of trioctylamine and the component (A) was changed to the copolymer shown in [Chemical Formula 26]. A positive resist composition 4 was prepared. The copolymer has a weight average molecular weight of 10,000, and p, q, and r are 30 mol%, 50 mol%, and 20 mol%, respectively.

Subsequently, the change of the film thickness of an unexposed coating film and an exposed coating film was measured by QCM like the evaluation example 14, and the graph of the film thickness value with respect to the same immersion time was obtained. This graph in this evaluation example is referred to as graph-4 (FIG. 4).
Further, when the maximum film thickness increase within 10 seconds from the start of measurement was determined in the same manner as in Evaluation Example 14, the unexposed film was 0.02 nm and the exposed film was 0.13 nm, and the film thickness was within 10 seconds. The maximum film thickness reduction amount was 0.26 nm for the unexposed film and 0.15 nm for the exposed film.

[Evaluation Example 18] (Evaluation Test 3)
A positive resist composition 3- (3) was prepared in the same manner as in the positive resist composition 3 used in Evaluation Example 10, except that triethanolamine was changed to 0.71 parts by mass of trioctylamine.
Subsequently, the change of the film thickness of an unexposed coating film and an exposed coating film was measured by QCM like the evaluation example 14, and the graph of the film thickness value with respect to the same immersion time was obtained. This graph in this evaluation example is referred to as graph-5 (FIG. 5).
Moreover, when the maximum film thickness increase amount within 10 seconds from the start of measurement was determined in the same manner as in Evaluation Example 14, the unexposed film was 0.50 nm and the exposed film was 0.44 nm. The maximum film thickness reduction amount was 0.04 nm for the unexposed film and 0 nm for the exposed film.

[Comparative Evaluation Example 7] (Evaluation Test 3)
The following component (A), component (B), and component (D) were uniformly dissolved in component (C) to prepare positive resist composition 13.
As the component (A), a copolymer composed of 64 mol% hydroxystyrene units and 36 mol% 1-ethoxy-1-ethyloxystyrene units was used. The mass average molecular weight of the prepared component (A) was 8,000.
As the component (B), 5 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used.
As the component (C), a mixed solvent (mass ratio 6: 4) of 1900 parts by mass of a mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.
As component (D), 0.71 part by mass of trioctylamine was used.
Next, the positive resist composition 13 was spin-coated on a silicon wafer and heated at 90 ° C. for 90 seconds to provide a resist coating film having a thickness of 150 nm. This is called an unexposed film. On the other hand, a large area (about 10 mm ² ) that can be visually confirmed using a KrF excimer laser (248 nm) with an exposure apparatus NSR-S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.60). ) The area was exposed. The exposure amount was 12 mJ / cm ² . Next, PEB treatment was performed at 110 ° C. for 90 seconds.
Subsequently, the change of the film thickness of an unexposed coating film and an exposed coating film was measured by QCM like the evaluation example 14, and the graph of the film thickness value with respect to the same immersion time was obtained. This graph in this comparative evaluation example is referred to as graph-6 (FIG. 6).
Further, when the maximum amount of increase in film thickness within 10 seconds from the start of measurement was determined in the same manner as in Evaluation Example 14, the unexposed coating film was found to be 0.00. nm, the exposed coating film was 1.55 nm, and the maximum film thickness reduction within 10 seconds was 0.27 nm for the unexposed film and 0 nm for the exposed film.

[Comparative Evaluation Example 8] (Evaluation Test 3)
The following component (A), component (B), and component (D) were uniformly dissolved in component (C) to prepare positive resist composition 14.
As the component (A), a copolymer composed of 60 mol% hydroxystyrene units, 15 mol% styrene units and 25 mol% tert-butyl acrylate units was used. The weight average molecular weight of the prepared component (A) was 12,000.
As the component (B), 5 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used.
As the component (C), a mixed solvent (mass ratio 6: 4) of 1900 parts by mass of a mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.
As component (D), 0.71 part by mass of trioctylamine was used.
Next, the positive resist composition 14 was spin-coated on a silicon wafer and heated at 115 ° C. for 90 seconds to provide a resist coating having a thickness of 150 nm. This is called an unexposed film. On the other hand, a large area (about 10 mm ² ) that can be visually confirmed using a KrF excimer laser (248 nm) with an exposure apparatus NSR-S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.60). The μm) area was exposed. The exposure amount was 12 mJ / cm ² . Next, PEB treatment was performed at 115 ° C. for 90 seconds.
Subsequently, the change of the film thickness of an unexposed coating film and an exposed coating film was measured by QCM like the evaluation example 14, and the graph of the film thickness value with respect to the same immersion time was obtained. This graph in this comparative evaluation example is referred to as graph-7 (FIG. 7).
Further, when the maximum amount of increase in film thickness within 10 seconds from the start of measurement was determined in the same manner as in Evaluation Example 14, the unexposed film was 1.13 nm and the exposed film was 0.22 nm. The maximum film thickness reduction amount was 0 nm for both the unexposed film and the exposed film.

[Comparative Evaluation Example 9] (Evaluation Test 3)
In the positive resist composition 10 used in Comparative Evaluation Example 1, triethanolamine was changed to 0.71 part by mass of trioctylamine, and component (B) was changed to 5 parts by mass of triphenylsulfonium nonafluorobutanesulfonate alone. A positive resist composition 10- (1) similar to that described above was prepared.
Subsequently, the change of the film thickness of an unexposed coating film and an exposed coating film was measured by QCM like the evaluation example 14, and the graph of the film thickness value with respect to the same immersion time was obtained. This graph in this comparative evaluation example is referred to as graph-8 (FIG. 8).
Further, when the maximum amount of increase in film thickness within 10 seconds from the start of measurement was determined in the same manner as in Evaluation Example 14, the unexposed film was 0.61 nm and the exposed film was 1.49 nm, which was within 10 seconds. The maximum film thickness reduction amount was 0 nm for both the unexposed film and the exposed film.

[Evaluation Example 19] (Evaluation Test 1)
In the positive resist composition 2 used in Evaluation Example 2, as the component (B), propylene glycol monomethyl ether was changed from a mixture of onium salts to 5.0 parts by mass of triphenylsulfonium nonafluorobutanesulfonate, and excluding γ-butyrolactone. A positive resist composition 2- (1) was prepared in the same manner except that the mixed solvent was 1900 parts by mass (mass ratio 6: 4) of a mixed solvent of acetate and ethyl lactate.
Next, a resist pattern was formed using the resist composition 2- (1) obtained above.
First, an organic antireflection film composition “AR-19” (trade name, manufactured by Shipley) is applied onto a silicon wafer using a spinner, and baked on a hot plate at 215 ° C. for 60 seconds to be dried. Thus, an organic antireflection film having a film thickness of 82 nm was formed. Then, the positive resist composition 2- (1) obtained above is applied onto the antireflection film using a spinner, prebaked on a hot plate at 115 ° C. for 90 seconds, and dried to reflect the resist. A resist layer having a thickness of 200 nm was formed on the prevention film.
Next, selective irradiation is performed using an ArF excimer laser (193 nm) with an exposure apparatus NSR-S302B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.60, 2/3 ring zone) through a mask pattern. did. Then, as a simulated immersion exposure treatment, pure water was continuously dropped at 23 ° C. for 2 minutes while rotating the silicon wafer provided with the resist layer after the exposure.
Next, PEB treatment was performed at 115 ° C. for 90 seconds, and further developed at 23 ° C. with an alkali developer for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

The thus obtained resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined.
In the resist composition 2- (1) of this evaluation example, Eop was 18.77 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, using the resist composition 2- (1) of this evaluation example, the simulated immersion exposure process is not performed, and the conventional normal lithography process, that is, the simulated immersion exposure process is not performed. When a resist pattern was formed by the same method, Eop was 19.03 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 1.4. When the sensitivity ratio of the simulated immersion exposure treatment to the sensitivity of normal exposure was determined (19.03 / 18.77), it was 1.01. Moreover, the resist pattern was not T-top shape and surface roughness was not seen, and it was favorable.

[Evaluation Examples 20 to 25] (Evaluation Test 1)
A positive resist composition in each evaluation example was prepared in the same manner as in Evaluation Example 19 except that the component (A) was changed to each resin shown in Table 4.
Next, in Evaluation Example 19, except that the prebaking and PEB temperatures were changed as shown in Table 4, the sensitivity X2 obtained by performing the simulated immersion exposure treatment and the simulated immersion exposure treatment were not obtained. The obtained sensitivity X1 was determined. And the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100 from these. These are shown in Table 4. Moreover, even if the resist pattern shape is subjected to a simulated immersion exposure process, there is a slight difference in all evaluation examples, but the resist pattern shape is not a T-top shape and surface roughness is not seen and is relatively good. there were.

[Evaluation Example 26] (Evaluation Test 1)
The following components (A), (B), and (D) were uniformly dissolved in component (C) to prepare a positive resist composition.
As the component (A), a copolymer of methacrylic acid esters composed of the three structural units shown in [Chemical Formula 33], and HS-CH ₂ —CH ₂ —CH ₂ — as a chain transfer agent in the polymerization. By using C (CF ₃ ) ₂ —OH, 100 parts by mass of a copolymer in which a —C (CF ₃ ) ₂ —OH group was introduced at the terminal of the copolymer was used. (A) Ratio of each structural unit p, q, and r used for preparation of component was p = 40 mol%, q = 40 mol%, and r = 20 mol%. In addition, this copolymer does not have an anhydride-containing structural unit of dicarboxylic acid and a phenolic hydroxyl group-containing structural unit. The mass average molecular weight of the prepared component (A) was 6400.

As the component (B), 3.7 parts by mass of triphenylsulfonium nonafluorobutanesulfonate and 1.0 part by mass of triphenylsulfonium trifluoromethanesulfonate were used.
As the component (C), a mixed solvent of 900 parts by mass (mass ratio 6: 4) of a mixed solvent of propylene glycol monomethyl ether acetate and ethyl lactate was used.
As the component (D), 0.8 part by mass of tris-2- (2-methoxy (ethoxy)) ethylamine was used.
Next, a resist pattern was formed using the positive resist composition obtained above.

First, an organic antireflection coating composition “DUV-42” (trade name, manufactured by Brewer Science) was applied onto a silicon wafer using a spinner, and baked on a hot plate at 185 ° C. for 60 seconds to dry. As a result, an organic antireflection film having a film thickness of 65 nm was formed. The positive resist composition obtained above is applied onto the antireflection film using a spinner, prebaked on a hot plate at 125 ° C. for 90 seconds, and dried to form a film on the antireflection film. A resist layer having a thickness of 350 nm was formed.
Next, selectively using a KrF excimer laser (248 nm) with an exposure apparatus NSR-S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.68, 2/3 annular zone) through a binary mask pattern. Irradiated. Then, as a simulated immersion exposure treatment, pure water was continuously dropped at 23 ° C. for 2 minutes while rotating the silicon wafer provided with the resist layer after the exposure.
Next, PEB treatment was performed at 110 ° C. for 90 seconds, and further developed at 23 ° C. with an alkali developer for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

The thus obtained resist pattern with a 150 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined.
In the positive resist composition of this evaluation example, Eop was 33.2 mJ / cm ² . This is X2. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.
On the other hand, the positive resist composition of this evaluation example was used, except that the simulated immersion exposure treatment was not performed and the conventional lithography process of normal exposure, that is, the simulated immersion exposure treatment was not performed. When a resist pattern was formed by such a method, Eop was 32.1 mJ / cm ² . Let this be X1.
Next, when the absolute value was determined from the formula [(X2 / X1) -1] × 100, it was 3.4. When the sensitivity ratio of the simulated immersion exposure treatment to the sensitivity of normal exposure was determined (33.2 / 32.1), it was 1.03. Moreover, the resist pattern was not T-top shape and surface roughness was not seen, and it was favorable.
Further, when the contact hole pattern was formed in the same manner except that the mask was replaced with a halftone mask, a hole resist pattern having a hole diameter of 160 nm was formed both in the case of the simulated immersion exposure process and in the case of not performing the simulated immersion exposure process. The resist pattern was not a T-top shape, and the surface was not rough and was good.

[Evaluation Examples 27 to 31] (Evaluation Test 2)
In Evaluation Examples 27 to 31, a positive resist composition in each evaluation example was prepared with the composition shown in Table 5, and the same method as in Evaluation Example 4 was used except that the mounting conditions shown in Table 6 were changed. Using “two-beam interference exposure apparatus that simulates pattern exposure light by irradiating two-beam interference light through a prism” (an experimental apparatus manufactured by Nikon Corporation) with pure water as an immersion solvent Then, immersion exposure (Evaluation Test 2) was performed using an ArF excimer laser with a wavelength of 193 nm as a light source. The results are shown in Table 7.

    As is apparent from the results in Table 7, it was found that if these resist compositions were applied to immersion lithography, for example, a line width of 55 nm and a pitch of about 110 nm could be sufficiently resolved. Moreover, about the resist pattern shape, the rectangularity was high and LER was also favorable.

[Evaluation Example 32] (Evaluation Test 1)
Using the resist composition of Evaluation Example 1, a resist film having a thickness of 150 nm was formed in the same manner as in Evaluation Example 1 except that the organic antireflection film was not used. In a state where the resist film was completely immersed in water, an open frame exposure (exposure without a mask) was performed with an ArF excimer laser (193 nm) using a simple exposure apparatus VUVES4500 (manufactured by RISOTEC Japan Co., Ltd.). . Next, PEB was applied on a hot plate at 115 ° C. for 90 seconds, and further developed at 23 ° C. with an alkaline developer for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used. The sensitivity at that time was 4.5 mJ / cm ² , and the portion exposed to light was completely dissolved.

[Comparative Evaluation Example 10] (Evaluation Test 1)
In Evaluation Example 32, the same method was used except that the resist film was not immersed in water. The sensitivity at that time was 4.5 mJ / cm ² , and the portion exposed to light was completely dissolved.

  From the results of Evaluation Example 32 and Comparative Evaluation Example 10, there was no significant difference between the case of exposure by immersion in water and the case of normal exposure. Therefore, even when an actual immersion exposure apparatus is used, it is expected that there is no influence by the immersion medium.

[Evaluation Example 33] (Evaluation Test 1)
The following component (A), component (B), component (D) and other components were uniformly dissolved in component (C) to prepare a positive resist composition.
As the component (A), 100 parts by mass of a methacrylic acid ester copolymer composed of the three structural units shown in [Chemical Formula 34] was used. (A) Ratio of each structural unit p, q, and r used for preparation of component was p = 40 mol%, q = 40 mol%, and r = 20 mol%. In addition, this copolymer does not have an anhydride-containing structural unit of dicarboxylic acid and a phenolic hydroxyl group-containing structural unit. The weight average molecular weight of the prepared component (A) was 8900.

As component (B), 5.0 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used.
As component (D), 0.3 parts by mass of triethanolamine was used.
As the component (C), a mixed solvent of ethyl lactate and propylene glycol monomethyl ether acetate (mass ratio 4: 6) was used so that the resist solid content concentration was 4.3% by mass.

Using the positive resist composition produced as described above, a simulation was performed in the same manner as in Evaluation Example 1 except that prebaking (PAB) was changed to 100 ° C. for 90 seconds and PEB was changed to 110 ° C. for 90 seconds. Pattern formation including immersion exposure processing was performed. At that time, a resist pattern having a 130 nm line and space of 1: 1 was observed with a scanning electron microscope (SEM), and the sensitivity (Eop) at that time was determined. The Eop was determined to be 15.3 mJ / cm ² . This is X2. Further, the resist pattern was good with no surface roughness.
On the other hand, using the resist composition of this evaluation example, the same method except that the simulated immersion exposure process is not performed and the conventional lithography process of normal exposure, that is, the simulated immersion exposure process is not performed. When the resist pattern was formed at, the Eop was 14.7 mJ / cm ² . Let this be X1.
Subsequently, when the absolute value was calculated | required from the formula of [(X2 / X1) -1] * 100, it was 4.0. When the sensitivity ratio of the simulated immersion exposure processing to the sensitivity of normal exposure was determined (15.3 / 14.7), it was 1.04. Moreover, the resist pattern was not T-top shape, and the surface roughness was not seen but it was favorable.

[Reference Example 1]
Using a quartz substrate to which no resist composition was applied, measurement was performed by QCM in the same manner as in Evaluation Example 14 to obtain a graph (FIG. 9).

[Reference Example 2]
Using a material in which polystyrene and poly-t-butyl methacrylate were dissolved in a solvent, the measurement was performed by QCM in the same manner as in Evaluation Example 14 to obtain a graph (FIG. 10).
There was little variation in the film thickness value, and the results supporting the consideration of the present invention were obtained.

  From all the above evaluation examples and comparative evaluation examples, that is, evaluation tests 1, 2 and 3, it can be seen that the present invention is extremely suitable for immersion lithography.

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Claims (3)

A method for evaluating a resist composition used in a resist pattern forming method including a step of immersion exposure,
A resist film is formed, selectively exposed, and subjected to a treatment for contacting the resist film with an immersion solvent used in the immersion exposure process, post-exposure heating (PEB), developed, and the resulting resist pattern formation performance is obtained. A method for evaluating a resist composition , comprising a step of evaluating and judging whether or not the resist composition is suitable for use in a resist pattern forming method including a step of immersion exposure .   The method for evaluating a resist composition according to claim 1, wherein the solvent is a solvent having a refractive index larger than that of air and smaller than that of the resist film. The method for evaluating a resist composition according to claim 1, wherein the solvent is water.

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