JP2022096214A - Method for manufacturing thickened resist pattern, thickening solution, and method for manufacturing processed substrate - Google Patents

Abstract

To provide a method for manufacturing a thickened resist pattern.SOLUTION: A method for manufacturing a thickened resist pattern comprises the following steps: (1) applying a resist composition above a substrate to form a resist layer from the resist composition; (2a) exposing the resist layer; (2b) applying a thickening solution comprising a polymer (A) and a solvent (B) to the resist layer to form a thickening layer; and (3) developing the resist layer and the thickening layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a thickened resist pattern, a thickening solution used for the method, and a method for producing a processed substrate.

In recent years, there has been an increasing need for high integration of LSIs, and there is a demand for miniaturization of resist patterns. In order to meet such needs, a lithography process using a short wavelength KrF excimer laser (248 nm), ArF excimer laser (193 nm), extreme ultraviolet (EUV; 13 nm), X-rays, electron beams, etc. has been put into practical use. It is going on.

In order to obtain a finer pattern, the resist pattern formed in a range stably obtained by the conventional method is covered with a composition containing a polymer, the resist pattern is thickened, and the hole diameter or the separation width is made finer. There is a method (for example, Patent Document 1). This is mainly intended to increase the width of the resist pattern, and the resist pattern is developed once and then a composition containing a polymer is further applied.
Further, while a thicker resist pattern having a high aspect ratio is required, a composition using a vinyl resin and an amine compound is being developed (Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-170190 Japanese Unexamined Patent Publication No. 2017-165846

The present inventors considered that there are still one or more problems that require improvement in the method for producing a resist pattern. They include, for example: thickening a fine resist pattern; obtaining a fine resist pattern useful as an etching mask; obtaining sufficient resolution even with an exposed machine with a numerical aperture; Obtain a good fine pattern; Obtain a resist pattern with a high aspect ratio; Widen the process window; Improve manufacturing yield.

The present inventors considered and examined as follows.
DOF (Depth of Focus) refers to the range of depth of focus in which a resist pattern can be formed with dimensions within a predetermined range when exposure is performed with the focus shifted up and down at the same exposure amount. ..
DOF is expressed by the following equation.
k2 × λ / NA ²
(In the formula, k2 is a constant, λ is the exposure wavelength, and NA is the numerical aperture.)
The larger the DOF, the wider the process window, which is preferable. However, in high-precision lithography techniques such as ICs, the NA of exposure equipment tends to increase in the future, and it is expected that the DOF will become narrower and narrower.

In EUV exposure, which is expected as a high-definition technique, it is being achieved to form a fine pattern with a thin film. The present inventors considered that it is preferable to thicken the resist pattern in order to make the resist pattern more resistant when the high-definition pattern is used as a mask in a subsequent step. If the resist pattern is thin, for example, when it is used as an etching mask, the durability as a mask cannot be achieved, and the object to be masked may be scraped at the end of the etching process.

If the resist film thickness is thick, the process window tends to be narrow. For example, the shape of the resist pattern formed when the Focus shakes due to a slight shake of the thickness of the substrate may change, and the resist pattern may become far from the rectangle, and the pattern may easily collapse. In another example, if the exposure amount (Dose) fluctuates, the line width fluctuates, and there is a possibility that pattern bridges and pattern collapses are likely to occur. In high-definition technology that requires high resolution, a thinner resist film is more likely to be used.

The present invention has been made based on the above-mentioned technical background, and provides a method for producing a thickened resist pattern and a thickening solution used thereof.

The method for producing a thickened resist pattern according to the present invention includes the following steps.
(1) Applying a resist composition above a substrate to form a resist layer from the resist composition;
(2a) Exposing the resist layer;
(2b) Applying a thickening solution containing the polymer (A) and the solvent (B) to the resist layer to form a thickening layer; and (3) developing the resist layer and the thickening layer. To do.

The thickening solution according to the present invention contains the polymer (A) and the solvent (B), and is used for thickening the resist layer applied before the development of the resist layer.

The method for manufacturing a processed substrate according to the present invention includes the following methods.
Forming the thickened resist pattern described above; and (4) processing the thickened resist pattern as a mask.

According to the present invention, one or more of the following effects can be desired.
Thicken a fine resist pattern; obtain a fine resist pattern useful as an etching mask; obtain sufficient resolution even when using an exposure machine with a numerical aperture; obtain a fine pattern with a good shape; aspect Obtain a high-ratio resist pattern; widen the process window; improve manufacturing yield.

The conceptual diagram which shows one form of the method of manufacturing the thickened resist pattern.

[Definition]
Unless otherwise specified herein, the definitions and examples provided in this paragraph are followed.
The singular includes the plural, and "one" and "that" mean "at least one." An element of a concept can be expressed by a plurality of species, and when the amount (eg, mass% or mol%) is described, the amount means the sum of the plurality of species.
"And / or" includes all combinations of elements and also includes single use.
When the numerical range is indicated by using "-" or "-", these include both endpoints and the unit is common. For example, 5 to 25 mol% means 5 mol% or more and 25 mol% or less.
Descriptions such as "C _x-y ", "C _x -C _y " and "C _x " mean the number of carbons in the molecule or substituent. For example, C _1-6 alkyl means an alkyl chain having 1 or more and 6 or less carbons (methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.).
If the polymer has multiple repeating units, these repeating units will copolymerize. These copolymers may be any of alternating copolymerization, random copolymerization, block copolymerization, graft copolymerization, or a mixture thereof. When a polymer or resin is indicated by a structural formula, n, m, etc., which are also written in parentheses, indicate the number of repetitions.
The unit of temperature is Celsius. For example, 20 degrees means 20 degrees Celsius.
The additive refers to the compound itself having the function (for example, in the case of a base generator, the compound itself that generates a base). It is also possible that the compound is dissolved or dispersed in a solvent and added to the composition. As one embodiment of the present invention, such a solvent is preferably contained in the composition according to the present invention as the solvent (B) or other components.

Hereinafter, embodiments of the present invention will be described in detail.

<Manufacturing method of thickened resist pattern>
The method for producing a thickened resist pattern according to the present invention includes the following steps.
(1) Applying a resist composition above a substrate to form a resist layer from the resist composition;
(2a) Exposing the resist layer;
(2b) A thickening solution containing a polymer (A) and a solvent (B) is applied to the resist layer to form a thickening layer; and (3) the resist layer and the thickening. To develop the layer.
Hereinafter, each step will be described with reference to the drawings. For clarity, steps (1) and (2) are performed before step (3). The numbers in parentheses indicating the process mean the order. However, the order of (2a) and (2b) is arbitrary. The same applies hereinafter.

Step (1)
In step (1), the resist composition is applied above the substrate to form a resist layer.
Examples of the substrate include a silicon / silicon dioxide coated substrate, a silicon nitride substrate, a silicon wafer substrate, a glass substrate, and an ITO substrate.
The resist composition is not particularly limited, but is preferably a chemically amplified resist composition from the viewpoint of forming a fine resist pattern with high resolution, for example, a chemically amplified PHS-acrylate hybrid EUV resist composition. Things can be mentioned. It is also a preferred embodiment that the resist composition contains a photoacid generator. A suitable resist composition of the present invention is a positive chemical amplification resist composition.
A typical high resolution positive resist composition comprises a combination of an alkali soluble resin having a side chain protected by a protecting group and a photoacid generator. When the resist layer formed from such a composition is irradiated with ultraviolet rays, electron beams, extreme ultraviolet rays, or the like, the photoacid generator releases an acid at the irradiated portion (exposed portion), and the acid causes an alkali-soluble resin. The protecting group bound to UV is dissociated (hereinafter referred to as deprotection). Since the deprotected alkali-soluble resin is soluble in the alkaline developer, it is removed by the developing process. In the case of the present application in which the thickened layer is formed on the resist layer, if the region of the lower resist layer is soluble, both the mixed layer and the resist layer in that region are removed. It will be described later.
As the resist composition of the present invention, a negative resist composition can also be used. Known negative resist compositions and processes can be used. For example, by insolubilizing the polymer with a cross-linking agent or using an organic solvent in the developing solution, both the resist layer and the mixed layer in the unexposed portion are removed.

A resist composition is applied above the substrate by a suitable method. Here, in the present invention, "above the substrate" includes a case where it is applied directly above the substrate and a case where it is applied via another layer. For example, a resist underlayer film (for example, SOC (Spin On Carbon) and / or an adhesion enhancing film) may be formed directly above the substrate, and the resist composition may be applied directly above the resist underlayer film (for example, SOC (Spin On Carbon) and / or adhesion enhancing film). Preferably, the resist composition is applied directly above the substrate. In still another preferred embodiment, the SOC is formed directly above the substrate, and the adhesion enhancing film is formed directly above the SOC, and the resist composition is applied directly above the SOC.
The application method is not particularly limited, and examples thereof include application by spin coating.
The substrate to which the resist composition is applied is preferably heated to form a resist layer. This heating is also called prebaking and is performed by, for example, a hot plate. The heating temperature is preferably 100 to 250 ° C; more preferably 100 to 200 ° C; still more preferably 100 to 160 ° C. The temperature here is the heating surface temperature of the hot plate. The heating time is preferably 30 to 300 seconds; more preferably 30 to 120 seconds; still more preferably 45 to 90 seconds. The heating is preferably carried out in an air or nitrogen gas atmosphere; more preferably in an air atmosphere.
FIG. 1 (i) is a schematic diagram in which a resist layer 2 is formed on a substrate 1. The film thickness of the resist layer is selected depending on the intended purpose, but is preferably 10 to 100 nm; more preferably 10 to 40 nm; still more preferably 10 to 30 nm.

Step (2a)
In step (2a), the resist layer is exposed, if desired, via a mask.
The wavelength of the radiation (light) used for the exposure is not particularly limited, but it is preferable to expose with light having a wavelength of 13.5 to 248 nm. Specifically, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), EUV (extreme ultraviolet rays, wavelength 13.5 nm) and the like can be used. EUV light is more preferred. These wavelengths are allowed in the range of ± 1%.
After exposure, post-exposure heating (PEB) can also be performed if necessary. The temperature of the PEB can be selected from the range of 70 to 150 ° C; preferably 80 to 120 ° C. The heating time of PEB can be selected from the range of 0.3 to 5 minutes; preferably 0.5 to 2 minutes.
FIG. 1 (ii) is a schematic view showing a state in which the resist layer 2 of a case using a typical positive chemical amplification resist composition is exposed through a mask. An acid is released from the photoacid generator to the exposed portion 4, whereby the polymer is deprotected and the alkali solubility is increased. In the unexposed portion 3, the alkali solubility of the polymer has not changed.

Step (2b)
In step (2b), a thickening solution containing the polymer (A) and the solvent (B) is applied to the resist layer to form a thickening layer. In the present invention, the thickening solution is not applied to the resist pattern (after the resist layer has been developed).
The application method is not particularly limited, and examples thereof include application by spin coating.
The substrate to which the thickening solution is applied is preferably heated or spin-dried (more preferably by heating) to form a thickening layer. Heating is performed, for example, on a hot plate. The heating temperature is preferably 45 to 150 ° C; more preferably 90 to 130 ° C. The heating time is preferably 30 to 180 seconds; more preferably 45 to 90 seconds. Heating is preferably carried out in an air or nitrogen gas atmosphere; more preferably in an air atmosphere. The heating in (2b) is also referred to as a mixing bake.
The order of (2a) and (2b) is arbitrary. Since it is not necessary to expose while transmitting through the thickened film layer, the step of performing (2b) after (2a) is more preferable. It is also possible to perform the step (2a) after (2b), and in this case, it is preferable to perform the exposure after controlling the influence of penetrating the thickened film layer.
FIG. 1 (iii) is a schematic view of a state in which a thickened film layer 5 is formed on a resist layer 2.

In step (2b), an insolubilized layer is preferably formed in the vicinity region where the thickened film layer and the resist layer are in contact with each other. Although not bound by theory, it is considered that the polymers infiltrate each other (intermixing) in the portion where the thickened film layer and the resist layer are in contact with each other to form a mixed layer. Whether the mixed layer is soluble or insoluble in the developer in the subsequent developing step depends on whether the underlying resist layer is soluble or insoluble in the developer. If the area of the lower resist layer is insoluble in the developer, the mixed layer becomes an insoluble layer. If the area of the lower resist layer is soluble in the developer, the mixed layer is also soluble.
An example of a positive resist layer will be described. Since the exposed portion of the resist layer is soluble in the developing solution, the resist layer (matrix component, preferably polymer) that has permeated the mixed layer in the same region is dissolved, and the mixed layer is also dissolved. It also dissolves the exposed portion of the resist layer below the mixed layer. On the other hand, the unexposed portion of the resist layer is insoluble in the developing solution (for example, it is not deprotected). Therefore, the resist layer permeating the mixed layer in the same region is insoluble, and the mixed layer is also insoluble. Also, the unexposed portion of the resist layer under the mixed layer does not dissolve.
FIG. 1 (iv) is a schematic view of a state in which the insolubilizing layer 6 is formed. A mixed layer is also formed in the melting region (exposed portion in the positive type), but it is not described in (iv) for convenience because it is melted and removed in the developing step.

In step (2b), it is also preferable to perform rinsing after forming the thickened layer to remove the upper part of the thickened layer (thickened layer above the mixed layer). As the rinse, one having the same composition as the solvent (B) of the thickening solution can be used, and water (for example, DIW) can be preferably used. The rinse in the present invention is different from the development described later. That is, the rinse is not for dissolving the soluble region of the resist layer to form a resist pattern.

[Thickening solution]
The thickening solution according to the present invention contains the polymer (A) and the solvent (B), and is used to thicken the resist layer applied before the development of the resist layer. The thickening solution according to the present invention is not applied between the resist patterns after development. However, the "development" after development does not include the development when the resist layer that has already been removed is patterned. For example, in the case of a design in which resist patterning is performed a plurality of times in succession, the thickening solution of the present invention is used to thicken the resist layer in the subsequent step even after the resist in the previous step is developed. It is possible to use it.

(A) Polymer The polymer (A) used in the present invention is not particularly limited as long as it has a good affinity with the resist pattern, and examples thereof include polyacrylic acid and vinyl resin.
Preferably, the polymer (A) is a polymer comprising an amino group in the repeating unit. Here, the amino group refers to a primary amino group (-NH ₂ ), a secondary amino group (-NHR), and a tertiary amino group (-NRR'). Here, the amino group includes those in which nitrogen is bonded to an adjacent element via a double bond, such as −N =. These amino groups may be contained in the side chain of the repeating unit or may be contained in the backbone structure of the polymer.

The polymer (A) is preferably a polymer comprising at least one of a repeating unit (A1) represented by the formula (a1) and a repeating unit (A2) represented by the formula (a2). It is more preferable that the polymer (A) contains a repeating unit (A1) represented by the formula (a1).

Ｒ^１１、Ｒ^１２およびＲ^１３は、それぞれ独立に、Ｈ、Ｃ_１－４アルキル、またはカルボキシである。Ｒ^１１およびＲ^１２は、好ましくはＨである。Ｒ^１３は、好ましくはＨまたはメチルであり；より好ましくはＨである。
Ｌ^１１は、単結合またはＣ_１－４アルキレンであり；好ましくは単結合またはメチレンであり；より好ましくは単結合である。
Ｒ^１４は、単結合、ＨまたはＣ_１－５アルキルであり；好ましくは単結合、Ｈ、メチル、ｎ－エチル、ｎ－プロピル、またはｎ－ブチルであり；より好ましくは単結合、Ｈまたはメチルである。Ｒ^１４が単結合である場合、Ｒ^１３と結合する。
Ｒ^１５は、Ｈ、Ｃ_１－５アルキル、Ｃ_１－５アシル、またはホルミル（－ＣＨＯ）であり；好ましくはＨ、メチル、ｎ－エチル、ｎ－プロピル、ｎ－ブチル、アセチルまたはホルミルであり；より好ましくはＨ、メチル、ｎ－エチルまたはｎ－プロピルであり；さらに好ましはＨまたはｎ－プロピルである。
Ｌ^１１のアルキル、Ｒ^１４のアルキル、およびＲ^１５のアルキルまたはアシル中の－ＣＨ_２－の少なくとも１つが、それぞれ独立に、－ＮＨ－に置換されていてもよい。好適には、Ｒ^１５のアルキルまたはアシル中の－ＣＨ_２－の１つが、－ＮＨ－に置換される。前記－ＮＨ－の置換が起こらない態様も、好適である。
Ｒ^１４の単結合またはアルキルと、Ｒ^１３のアルキルとが、共に結合して、飽和または不飽和のヘテロ環を形成していてもよい。好適にはＲ^１４の単結合とＲ^１３のアルキルが、結合し飽和のヘテロ環を形成する。前記ヘテロ環を形成しない態様も、好適である。
Ｒ^１４のアルキルと、Ｒ^１５のアルキル、アシルまたはホルミルとが、共に結合して、飽和または不飽和のヘテロ環を形成していてもよい。好適にはＲ^１４のアルキルとＲ^１５のアルキルが結合し、不飽和のヘテロ環を形成する。前記結合に使われるＲ^１４および又はＲ^１５中の－ＣＨ_２－は、前記－ＮＨ－の置換が行われても良い。前記ヘテロ環を形成しない態様も、好適である。
ｍ１１およびｍ１２は、それぞれ独立に、０～１の数であり；好ましくは０または１であり；より好ましくは０である。 The repeating unit (A1) represented by the formula (a1) is as follows.

R ¹¹ , R ¹² and R ¹³ are independently H, C _1-4 alkyl, or carboxy, respectively. R ¹¹ and R ¹² are preferably H. R ¹³ is preferably H or methyl; more preferably H.
L ¹¹ is single bond or C _1-4 alkylene; preferably single bond or methylene; more preferably single bond.
^R14 is single bond, H or C _1-5 alkyl; preferably single bond, H, methyl, n-ethyl, n-propyl, or n-butyl; more preferably single bond, H or methyl. Is. If R ¹⁴ is a single bond, it binds to R ¹³ .
^R15 is H, C _1-5 alkyl, C _1-5 acyl, or formyl (-CHO); preferably H, methyl, n-ethyl, n-propyl, n-butyl, acetyl or formyl. More preferably H, methyl, n-ethyl or n-propyl; even more preferred is H or n-propyl.
^At least one of -CH _2- ⁱⁿ the alkyl of ^L11 , the alkyl of R14, and the alkyl or acyl of R15 may each be independently substituted with -NH-. Preferably, _{one of -CH 2-} ⁱⁿ the alkyl or acyl of R15 is replaced with -NH-. An embodiment in which the substitution of -NH- does not occur is also preferable.
The single bond or alkyl of R ¹⁴ and the alkyl of R ¹³ may be bonded together to form a saturated or unsaturated heterocycle. Preferably, the single bond of R ¹⁴ and the alkyl of R ¹³ combine to form a saturated heterocycle. The embodiment that does not form the heterocycle is also suitable.
The alkyl of ^R14 and the alkyl, acyl or formyl of ^R15 may be combined together to form a saturated or unsaturated heterocycle. Preferably, the alkyl of ^R14 and the alkyl of ^R15 combine to form an unsaturated heterocycle. -CH _2- in R ¹⁴ and / or R ¹⁵ used for the binding may be substituted with the -NH-. The embodiment that does not form the heterocycle is also suitable.
m11 and m12 are independently numbers of 0 to 1; preferably 0 or 1; more preferably 0.

The repeating unit of P1: polyvinylimidazole described later will be described by the formula (a1). m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is a single bond. R ¹⁴ is methyl. R ¹⁵ is C ₃ alkyl (n-propyl) and one of -CH _2- is replaced with -NH-. Further, the alkyl of ^R14 and the alkyl of ^R15 are bonded to form an unsaturated heterocycle (imidazole).
The repeating unit of P2: polyallylamine described later will be described by the formula (a1). m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is methylene. R ¹⁴ and R ¹⁵ are H.
The repeating unit of P3: vinylpyrrolidone-vinylimidazole copolymer described later will be described by the formula (a1). The polymer having (A1) has two kinds of repeating units, each of which is represented by the formula (a1). The relevant part of vinyl imidazole is the same as that of P1 described above. Vinylpyrrolidone The relevant parts will be described. m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is a single bond. R ¹⁴ is C ₂ alkyl (ethyl). ^R15 is a _C2 acyl ( _CH3 -CO-, acetyl). The alkyl of ^R14 and the acyl of R15 are bonded to form a saturated heterocycle ⁽ 2-pyrrolidone). The repeating unit of the vinyl imidazole-corresponding part and the vinylpyrrolidone-corresponding part is 4: 6, and random copolymerization is performed.

下記繰り返し単位を式（ａ１）で説明する。ｍ１１＝ｍ１２＝０である。Ｒ^１１、Ｒ^１２およびＲ^１３はＨである。Ｌ^１１は単結合である。Ｒ^１４はＣ_４アルキル（ｎ－ブチル）である。Ｒ^１５はＣ_２アシル（ＣＨ_３－ＣＯ－、アセチル）である。Ｒ^１４のアルキルとＲ^１５のアシルが結合し、飽和ヘテロ環を形成している。

The following repeating unit of polydialylamine will be described by the formula (a1). m11 = m12 = 1. R ¹¹ and R ¹² are H. L ¹¹ is methylene and R ¹³ is methyl. R ¹⁴ is a single bond and binds to R ¹³ to form a saturated heterocycle. R ¹⁵ is H.

The following repeating unit will be described by the equation (a1). m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is a single bond. R ¹⁴ is _C4 alkyl (n-butyl). ^R15 is a _C2 acyl ( _CH3 -CO-, acetyl). The alkyl of ^R14 and the acyl of ^R15 are bonded to form a saturated heterocycle.

Examples of the polymer having (A1) include polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, and vinylpyrrolidone-vinylimidazole copolymer. The polymer (A) may be a copolymer having two or more kinds of (A1), and examples thereof include vinylpyrrolidone-vinylimidazole copolymer or poly (allylamine-co-diallylamine). Preferably, the polymer having (A1) contains one or two repeating units; more preferably one. When a copolymer is used, the repeating unit contained in the polymer having (A1) is preferably two kinds.

ここで、
Ｒ^２１は、それぞれ独立に、Ｈ、単結合、Ｃ_１－４アルキルまたはカルボキシ（－ＣＯＯＨ）であり；好ましくはＨ、単結合またはメチルであり；より好ましくはＨまたは単結合であり；さらに好ましくはＨである。Ｒ^２１の単結合は、別の繰り返し単位（Ａ２）への繰り返し単位に使用される。ポリマーの末端で使用されない単結合は、Ｈ等が結合しても良い。
Ｒ^２２、Ｒ^２３、Ｒ^２４、Ｒ^２５は、それぞれ独立に、Ｈ、Ｃ_１－４アルキルまたはカルボキシであり；好ましくはＨまたはメチルであり；より好ましくはＨである。
ｍ２１は０～３の数であり；好ましくは０または１であり；より好ましくは１である。 The repeating unit (A2) represented by the formula (a2) is as follows.

here,
R ²¹ is independently H, single bond, C _1-4 alkyl or carboxy (-COOH); preferably H, single bond or methyl; more preferably H or single bond; even more preferred. Is H. The single bond of R ²¹ is used as a repeating unit to another repeating unit (A2). The single bond not used at the end of the polymer may be bound to H or the like.
R ²² , R ²³ , R ²⁴ , and R ²⁵ are independently H, C _1-4 alkyl or carboxy; preferably H or methyl; more preferably H.
m21 is a number from 0 to 3; preferably 0 or 1; more preferably 1.

Examples of the polymer having (A2) include polyethyleneimine. Polyallylamine may be linear or branched; linear is more preferred.
Linear polyethyleneimine will be described by the formula (a2). m21 = 1, and R ²¹ , R ²² , R ²³ , R ²⁴ , and R ²⁵ are H.
The branched polyethyleneimine will be described by the formula (a2). m21 = ¹ and R21 is H or a single bond. R ²² , R ²³ , R ²⁴ and R ²⁵ are H.
The polymer (A) may be a copolymer having two or more kinds of (A2). Preferably, the polymer having (A2) contains one or two repeating units; more preferably one. The polymer (A) may be a copolymer having (A1) and (A2).

The polymer (A) can be appropriately selected from the above-mentioned ones from the viewpoint of the type of resist composition to be applied, the availability of the polymer, and the like, and is preferably polyvinylimidazole, polyvinylamine, polyallylamine, and poly. It is selected from the group consisting of diallylamine, polyethyleneimine, vinylpyrrolidone-vinylimidazole polymer and poly (allylamine-co-diallylamine).

The polymer (A) may be a copolymer containing a repeating unit containing no amino group as long as the scope of the present invention is not impaired. For example, a copolymer containing polyacrylic acid, polymethacrylic acid, polyvinyl alcohol and the like as a copolymerization unit can be mentioned.

Considering the affinity with the polymer in the resist, the repeating unit containing no amino group is preferably 50 mol% or less based on the total repeating unit constituting the polymer (A); 30 mol% or less. More preferably; 5 mol% or less is even more preferred. It is also a preferred embodiment of the present invention that the repeating unit containing no amino group is 0 mol% (not contained).

The mass average molecular weight of the polymer (A) is preferably 5,000 to 200,000; more preferably 5,000 to 150,000; still more preferably 6,000 to 10,000. In the present invention, the mass average molecular weight means a polystyrene-equivalent average mass molecular weight measured by gel permeation chromatography.

The content of the polymer (A) is preferably 1 to 30% by mass; more preferably 1 to 20% by mass; still more preferably 2 to 10% by mass, based on the total mass of the thickening solution. be.
Although the thickening solution contains the polymer (A), it may contain a polymer other than the polymer (A) (preferably a polymer having a repeating unit containing no amino group). The content of the polymer other than the polymer (A) is preferably 0 to 20% by mass; more preferably 0 to 10% by mass; still more preferably 0 to 5% based on the total mass of the thickening solution. It is% by mass; more preferably 0% by mass (a mode not included).

(B) Solvent The solvent (B) is for dissolving the polymer (A) and other components used as needed. It is necessary that such a solvent does not dissolve the resist layer. The solvent (B) preferably contains water. The water is preferably deionized water (DIW). Since it is used for forming a fine resist pattern, it is preferable that the solvent (B) has few impurities. The preferred solvent (B) has impurities of 1 ppm or less; more preferably 100 ppb or less; still more preferably 10 ppb or less. It is also a preferred embodiment of the present invention to prepare a thickening solution by filtering a solution in which a solute is dissolved for use in a fine process.
The content of water is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, still more preferably 98 to 100% by mass, and more preferably, based on the total mass of the solvent (B). More preferably, it is 100% by mass. As a preferred embodiment of the present invention, the solvent (B) comprises substantially only water. However, an embodiment in which the additive is dissolved and / or dispersed in a solvent other than water (for example, a surfactant) and contained in the thickening solution according to the present invention is acceptable as a preferred embodiment of the present invention. ..

Specific examples of the solvent (B) excluding water include, for example, cyclohexanone, cyclopentanone, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, and the like. Diethyl glycol diethyl ether, propylene glycol 1-monomethyl ether 2-acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, γ-butyrolactone, ethyl lactate, or a mixture thereof are suitable. These are preferable in terms of storage stability of the solution. These solvents can also be used as a mixture of two or more.

The content of the solvent (B) is preferably 70 to 99% by mass; more preferably 80 to 99% by mass; still more preferably 90 to 98% by mass, based on the total mass of the thickening solution. be.
The pH of the entire thickening solution is preferably 5-12; more preferably 7-12; even more preferably 9-12.

(C) Acid The thickening solution according to the present invention can further contain an acid (C). Without being bound by theory, it is believed that the inclusion of the acid (C) makes it possible to control the pH of the thickened solution, which tends to be basic due to the polymer (A). It is considered that the dissolution of the polymer in the partially deprotected resist layer existing on the surface of the resist layer can be suppressed.
Examples of the acid (C) include sulfonic acid, carboxylic acid, sulfuric acid, nitric acid, or at least a mixture of any two of these; preferably sulfonic acid, sulfuric acid or nitric acid; more preferably sulfonic acid, or It is nitric acid. Examples of the sulfonic acid include p-toluene sulfonic acid, benzene sulfonic acid, p-dodecylbenzene sulfonic acid, 1,4-naphthalenedi sulfonic acid and methane sulfonic acid; preferably p-toluene sulfonic acid. Examples of the carboxylic acid include acetic acid, formic acid, oxalic acid, maleic acid, fumaric acid, o-phthalic acid, and succinic acid.
The overall pH can be controlled by the amount of the acid (C) added. It is preferable not to use a strong acid that denatures the resist film as the acid (C). For example, it is preferable that the resist film is not deprotected by the acid (C).

The content of the acid (C) is preferably 0 to 20% by mass; more preferably 0 to 15% by mass; still more preferably 0.1 to 10% by mass, based on the total mass of the thickening solution. %; More preferably 0.1-5% by mass. It is also a preferred embodiment of the present invention that the thickening solution does not contain the acid (C) (0% by weight).

(D) Surfactant The thickening solution according to the present invention can further contain a surfactant (D). By containing the surfactant (D), the coatability can be improved. Examples of the surfactant that can be used in the present invention include (I) anionic surfactant, (II) cationic surfactant, and (III) nonionic surfactant, and more specifically. (I) Alkyl sulfonate, Alkyl benzene sulfonic acid, and Alkyl benzene sulfonate, (II) Lauryl pyridinium chloride, and Lauryl methyl ammonium chloride, and (III) Polyoxyethylene octyl ether, Polyoxyethylene lauryl ether, Polyoxyethylene acetylenic. Glycol ethers, fluorine-containing surfactants (eg Florard (3M), Megafuck (DIC), Sulflon (Asahi Glass), and organic siloxane surfactants (eg KF-53, KP341 (Shinetsu Chemical Industry)) can be mentioned. ..
These surfactants can be used alone or in admixture of two or more.

The content of the surfactant (D) is preferably 0 to 5% by mass; more preferably 0.001 to 2% by mass; still more preferably 0. It is 01 to 1% by mass. It is also one embodiment of the present invention that the surfactant (D) is not contained (0% by mass).

(E) Additive The thickening solution according to the present invention may further contain an additive (E) other than the above-mentioned components (A) to (D). The additive (E) is preferably a plasticizer, a cross-linking agent, an antibacterial agent, a bactericidal agent, a preservative, an antifungal agent, a base, or at least a mixture thereof. Preferably, the additive (E) comprises a base; more preferably consists of a base. The base is a small molecule compound, unlike the polymer (A) containing an amino group. The molecular weight of the small molecule compound is 50-200; preferably 70-150; more preferably 100-125.
Examples of such a base include tertiary amines, diamines and amine compounds having a cage-type three-dimensional structure.
As diamine compounds, N, N, N', N'-tetramethylethylenediamine, N, N, N', N'-tetraethylethylenediamine, N, N, N', N'-tetrapropylethylenediamine, N, N, N ', N'-Tetraisopropylethylenediamine, N, N, N', N'-Tetramethyl-1,2-propylenediamine, N, N, N', N'-Tetraethyl-1,2-propylenediamine, N, N, N', N'-tetrapropyl-1,2-propylene diamine, N, N, N', N'-tetraisopropyl-1,2-propylene diamine, N, N, N', N'-tetramethyl -1,3-propylene diamine, N, N, N', N'-tetraethyl-1,3-propylene diamine, N, N, N', N'-tetrapropyl-1,3-propylene diamine, N, N , N', N'-tetraisopropyl-1,3-propylene diamine, N, N, N', N'-tetramethyl-1,2-butylenediamine, N, N, N', N'-tetraethyl-1 , 2-Butylenediamine, N, N, N', N'-Tetrapropyl-1,2-Butylenediamine, N, N, N', N'-Tetraisopropyl-1,2-Butylenedamine, N, N, N', N'-tetramethyl-1,3-butylenediamine, N, N, N', N'-tetraethyl-1,3-butylenediamine, N, N, N', N'-tetrapropyl-1, 3-Butylenediamine, N, N, N', N'-Tetraisopropyl-1,3-Butylenedamine, N, N, N', N'-Tetramethyl-1,4-Butylenedamine, N, N, N ', N'-tetraethyl-1,4-butylenediamine, N, N, N', N'-tetrapropyl-1,4-butylenediamine, and N, N, N', N'-tetraisopropyl-1, Examples include 4-butyrene diamine.
As amine compounds having a cage-type three-dimensional structure, 1,4-diazabicyclo [2.2.2] octane, 2-methyl-1,4-diazabicyclo [2.2.2] octane, 1,4-diazabicyclo [2] .2.2] Octane-2-one, 1,4-diaza-2-oxabicyclo [2.2.2] octane, 1,5-diazabicyclo [3.2.2] nonane, 1,5-diazabicyclo [ 3.3.2] decane, and 1,5-diazabicyclo [3.3.3] undecane. It is a preferred embodiment of the present invention that the base of the additive (E) is 1,4-diazabicyclo [2.2.2] octane. Although not bound by theory, it is considered that the inclusion of the base of the additive (E) promotes the permeation of the thickening solution into the resist layer, and the underlying resist layer further expands.

The content of the additive (E) is preferably 0 to 10% by mass, more preferably 0.001 to 5% by mass, and even more preferably 0.01, based on the total mass of the thickening solution. It is -4% by mass; more preferably 0.1-3% by mass. It is also a preferred embodiment of the present invention that the thickening solution according to the present invention does not contain the additive (E) (0% by mass).

Step (3)
In step (3), the resist layer and the thickened layer are developed.
Examples of the method of applying the developer include a paddle method, a dip method, and a spray method. The temperature of the developer is preferably 5 to 50 ° C; more preferably 25 to 40 ° C, and the development time is preferably 15 to 120 seconds; more preferably 30 to 60 seconds. After applying the developer, the developer is removed. The resist pattern after development can also be rinsed. The rinsing treatment can preferably be carried out with water (DIW).
The developer is preferably an alkaline aqueous solution or an organic solvent; more preferably an alkaline aqueous solution. Examples of the alkaline aqueous solution include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate and sodium silicate, organic amines such as ammonia, ethylamine, propylamine, diethylamine, diethylaminoethanol and triethylamine, and tetramethylammonium hydroxide (TMAH). Examples thereof include an aqueous solution containing the quaternary amine of the above; more preferably a TMAH aqueous solution; still more preferably a 2.38 mass% TMAH aqueous solution.
The above-mentioned surfactant can be further added to the developing solution.

FIG. 1 (v) shows a state in which a developer is applied to the resist layer and the thickened layer, the developer is removed, and the thickened resist pattern 7 is formed.
When (height of the thickened resist pattern)-(height of the resist pattern formed in the same manner except that the thickening solution is not applied) is taken as the thickening amount, the thickening amount is preferable. Is 2 to 20 nm; more preferably 2 to 15 nm; even more preferably 3 to 10 nm; even more preferably 3 to 8 nm. Although not bound by theory, in high-definition lithography techniques such as EUV exposure, the thickness of the resist film is generally thin. When used as an etching mask, it is considered possible to ensure the durability of the mask.

<Manufacturing method of processed circuit boards and devices>
The method for manufacturing a processed circuit board according to the present invention includes the following manufacturing methods.
Forming the thickened resist pattern described above; and (4) processing the thickened resist pattern as a mask.

Step (4)
In step (4), processing is performed using the thickened resist pattern as a mask.
The thickened resist pattern is preferably used for processing a resist underlayer film or a substrate (more preferably a substrate). Specifically, using the resist pattern as a mask, various substrates can be processed by using a dry etching method, a wet etching method, an ion implantation method, a metal plating method, or the like. Since the resist pattern has a thick film, it can function as a mask even under harsher conditions, so that it is suitably used for processing by a dry etching method.
When the resist underlayer film is processed using the thickened resist pattern, the processing may be performed step by step. For example, the resist pattern may be used to process the adhesion enhancing film and the SOC, and the SOC pattern may be used to process the substrate. As the adhesion enhancing film, for example, SiARC (Si antireflection film) can be used.

The method for manufacturing a device according to the present invention includes the above method, and preferably further includes a step of forming wiring on a processed substrate. Known methods can be applied to these processes. Then, if necessary, the substrate is cut into chips, connected to a lead frame, and packaged with resin. In the present invention, this packaged device is referred to as a device. Examples of the device include a semiconductor element, a liquid crystal display element, an organic EL display element, a plasma display element, and a solar cell element. The device is preferably a semiconductor device.

The present invention will be described below with reference to various examples. The aspect of the present invention is not limited to these examples.

表中、
・Ｐ１：ポリビニルイミダゾール（Ｍｗ ３０，０００）、

・Ｐ２：ポリアリルアミン（Ｍｗ ８，０００）、

・Ｐ３：ビニルピロリドン、ビニルイミダゾール、ランダムｃｏポリマー（ｍ：ｎ＝４：６、Ｍｗ ２５，０００）、

・Ｓ１：以下の構造を有するアセチレン系ジオールポリオキシアルキレンエーテル。

[Preparation of thickening solutions 1 to 3]
The polymer (A), surfactant (D), and base (E) shown in Table 1 are dissolved in the solvent (B). The respective compounding amounts are as shown in Table 1. The numerical values in Table 1 are the contents (mass%) of each component based on the total mass of the thickening solution.
The resulting solution is stirred at room temperature for 60 minutes. After visually confirming that the solute is completely dissolved, this solution is filtered through a 0.2 μm fluororesin filter to obtain thickening solutions 1 to 3.

In the table,
-P1: Polyvinylimidazole (Mw 30,000),

-P2: Polyallylamine (Mw 8,000),

P3: vinylpyrrolidone, vinylimidazole, random copolymer (m: n = 4: 6, Mw 25,000),

S1: An acetylene-based diol polyoxyalkylene ether having the following structure.

[Example 1]
The silicon substrate is treated with HMDS (hexamethyldisilazane) at 90 ° C. for 30 seconds. A chemically amplified PHS-acrylate hybrid resist composition (positive type) is applied to the HMDS-treated substrate by spin coating and heated on a hot plate at 110 ° C. for 60 seconds to form a resist layer having a film thickness of 35 nm. The resist layer is exposed using an EUV exposure apparatus (NXE: 3300B, ASML) through a mask having a size of 18 nm (line: space = 1: 1) while changing the exposure amount. Then, after exposure, heating (PEB) is performed at 100 ° C. for 60 seconds. Then, the thickening solution 1 is applied onto the resist layer by spin coating to form a thickening layer, and the mixture is heated at 130 ° C. for 60 seconds. Then, paddle development is performed for 30 seconds using a 2.38 mass% TMAH aqueous solution as a developer, water begins to be dropped while the developer is paddled on the substrate, and water is dropped while rotating the substrate. Subsequently, the developer is replaced with water. Then, the substrate is rotated at high speed to dry the thickened resist pattern of Example 1.

For comparison, a resist pattern is formed in which the thickening solution is not applied. Specifically, a resist pattern is formed in the same manner as in Example 1 except that the thickening solution is applied and the subsequent heating is not performed. This is called a comparative resist pattern.

[evaluation]
A section of the substrate was prepared for each of the thickened resist pattern and the comparative resist pattern of Example 1, and the cross-sectional shape was observed with SEM (SU8230, Hitachi High-Tech Fieldings), and the height of the pattern was observed. To measure. (Height of thickened resist pattern)-(Comparative resist pattern) is calculated as the thickening amount. The results obtained are shown in Table 2.
In Examples 2 and 3, the thickening amount is calculated in the same manner except that the type of the thickening solution is changed to that shown in Table 2. The results obtained are shown in Table 2.

1. 1. Substrate 2. Resist layer 3. Unexposed part 4. Exposure section 5. Thickened layer 6. Insolubilizing layer 7. Thickened resist pattern 8. Height of thickened resist pattern

Claims (15)

A method for producing a thickened resist pattern, which comprises the following steps.
(1) Applying a resist composition above a substrate to form a resist layer (preferably by heating) from the resist composition;
(2a) Exposing the resist layer (preferably with EUV light);
(2b) Applying a thickening solution containing the polymer (A) and the solvent (B) to the resist layer to form a thickening layer (preferably by heating or spin-drying); and ( 3) The resist layer and the thickened layer are developed (preferably developed with an alkaline aqueous solution or an organic solvent; more preferably developed with an alkaline aqueous solution). The method of claim 1, further comprising removing the upper portion of the thickened layer by rinsing after forming the thickened layer in step (2b). The method according to claim 1 or 2, wherein in a step (2b), an insolubilized layer is formed in a region in the vicinity where the thickened layer and the resist layer are in contact with each other. The method according to any one of claims 1 to 3, wherein the polymer (A) is a polymer containing an amino group in a repeating unit. The polymer (A) is a polymer comprising at least one of a repeating unit (A1) represented by the formula (a1) and a repeating unit (A2) represented by the formula (a2). The method according to any one of 1 to 4.

here,
R ¹¹ , R ¹² and R ¹³ are independently H, C _1-4 alkyl, or carboxy (preferably H), respectively.
L ¹¹ is a single bond or C _1-4 alkylene,
R ¹⁴ is a single bond, H or C _1-5 alkyl and is
R ¹⁵ is H, C _1-5 alkyl, C _1-5 acyl, or formyl.
Here, at least one of _—CH2- ⁱⁿ the alkyl of ^L11 , the alkyl of ^R14 , and the alkyl or acyl of R15 may each be independently substituted with —NH—.
The single bond or alkyl of R ¹⁴ and the alkyl of R ¹³ may be bonded together to form a saturated or unsaturated heterocycle.
The alkyl of ^R14 and the alkyl, acyl or formyl of ^R15 may be combined together to form a saturated or unsaturated heterocycle.
m11 and m12 are independently numbers from 0 to 1.

here,
R ²¹ is independently H, single bond, C _1-4 alkyl or carboxy (preferably H).
R ²² , R ²³ , R ²⁴ , and R ²⁵ are independently H, C _1-4 alkyl or carboxy (preferably H), respectively.
m21 is a number from 0 to 3. The polymer (A) is selected from the group consisting of polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, polyethyleneimine, vinylpyrrolidone-vinylimidazole copolymer, and poly (allylamine-co-diallylamine). The method according to any one of 5. The method according to at least one of claims 1 to 3, wherein the solvent (B) contains water.
Preferably, the content of the water is 80 to 100% by mass (more preferably 90 to 100% by mass; more preferably 98 to 100% by mass; still more preferably 98 to 100% by mass; based on the total mass of the solvent (B). 100% by mass);
Preferably, the content of the polymer (A) is 1 to 30% by mass (more preferably 1 to 20% by mass; still more preferably 2 to 10% by mass) based on the total mass of the thickened solution. Yes; or preferably, the content of the solvent (B) is 70 to 99% by mass (more preferably 80 to 99% by mass; still more preferably 90 to 98% by mass, based on the total mass of the thickened solution. %). The method according to at least one of claims 1 to 7, wherein the thickening solution further contains an acid (C).
Preferably, the content of the acid (C) is 0 to 20% by mass (more preferably 0 to 15% by mass; still more preferably 0.1 to 10% by mass) based on the total mass of the thickened solution. More preferably 0.1-5% by mass);
Preferably, the pH of the entire thickening solution is 5-12 (more preferably 5-10; even more preferably 6-9); or preferably the acid (C) is a sulfonic acid. , Carboxylic acid, sulfuric acid, nitric acid, or at least a mixture of any two of these. The method according to at least one of claims 1 to 8, wherein the thickening solution further contains a surfactant (D).
Preferably, the content of the surfactant (D) is 0 to 5% by mass (more preferably 0.001 to 2% by mass; still more preferably 0.01) based on the total mass of the thickening solution. ~ 1% by mass);
Preferably, the thickening solution further comprises the additive (E);
Preferably, the additive (E) is a plasticizer, a cross-linking agent, an antibacterial agent, a fungicide, a preservative, an antifungal agent, a base, or at least a mixture thereof; or preferably, an additive (E). ) Is 0 to 10% by mass (preferably 0.001 to 5% by mass; more preferably 0.01 to 4% by mass) based on the total mass of the thickening solution. The method according to any one of claims 1 to 9, wherein the resist composition is a chemically amplified resist composition. The method of claim 10, wherein the resist composition further comprises a photoacid generator. A thickening solution for thickening a resist layer applied before development of a resist layer, which comprises a polymer (A) and a solvent (B). The thickening solution according to claim 12, wherein the thickening solution is not applied between resist patterns. A method for manufacturing a processed circuit board including the following steps.
Forming the thickened resist pattern according to at least one of claims 1 to 11; and (4) processing the thickened resist pattern as a mask. A method of manufacturing a device, comprising the method of claim 14.
Preferably, it further comprises the step of forming wiring on the machined substrate; or preferably, the device is a semiconductor device.

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