KR102167485B1 - Mask blank manufacturing method and a method of manufacturing mask for transfer - Google Patents

Abstract

A method of manufacturing a mask blank and a transfer mask is provided for obtaining a mask blank and a transfer mask having a small non-uniformity in the sensitivity distribution in the surface of a formed resist film. A method for manufacturing a mask blank comprising forming a resist film made of a resist material on a substrate, wherein the formation of the resist film comprises a dropping step for dripping a resist liquid containing a resist material and a solvent onto the square-shaped substrate. In the dropping process, when the rotation speed of the substrate at time t is R(t), the rotation speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid is 300 to 2000 rpm It is a manufacturing method of phosphorus, a mask blank.

Description

A manufacturing method of a mask blank and a manufacturing method of a transfer mask TECHNICAL FIELD [MASK BLANK MANUFACTURING METHOD AND A METHOD OF MANUFACTURING MASK FOR TRANSFER}

The present invention relates to a mask blank and a method of manufacturing a transfer mask. In particular, the present invention relates to a method for manufacturing a mask blank, including forming a resist film made of a resist material on a substrate, and a method for manufacturing a transfer mask for semiconductor device manufacturing using the same.

In the manufacture of a transfer mask by a photolithography method, a mask blank having a thin film (for example, a light shielding film) for forming a transfer pattern (mask pattern) on a substrate such as a glass substrate is used. The manufacture of a transfer mask using this mask blank includes an exposure process for drawing a desired pattern on a resist film formed on the mask blank, a developing process for developing the resist film according to the desired pattern drawing to form a resist pattern, and It has an etching process of etching the thin film according to a resist pattern and a process of peeling and removing the remaining resist pattern. In the above developing step, after a desired pattern is drawn on the resist film formed on the mask blank, a developer is supplied to dissolve a portion of the resist film soluble in the developer to form a resist pattern. Further, in the above etching step, the resist pattern is used as a mask to dissolve the exposed portion of the thin film on which the resist pattern is not formed by dry etching or wet etching, thereby forming a desired mask pattern on the light-transmitting substrate. In this way, the transfer mask is completed.

Conventionally, when manufacturing a mask blank by forming a resist film on a square-shaped substrate or on a thin-film-attached substrate having a thin film deposited on the substrate, the resist is rotated using a rotating coating device that applies a resist solution by rotating the substrate. The application method is generally used. As an example of this rotational coating method, Patent Document 1 describes a resist rotational coating method for forming a uniform resist film without forming a thick film on four corners of the substrate. Specifically, Patent Document 1 discloses a homogenization process in which the film thickness of a resist is substantially uniform by rotating the substrate at a predetermined rotation speed and time, and a substrate at a rotation speed lower than the set rotation speed of the homogenization process following the homogenization process. A resist coating method comprising a drying step of substantially maintaining the thickness of the resist film obtained by the homogenization step by rotating and drying the homogenized resist is disclosed.

In addition, in Patent Document 2, a resist liquid containing a resist material and a solvent is dropped onto a square-shaped substrate, and the substrate is rotated to expand the dropped resist liquid onto the substrate. A method for manufacturing a mask blank comprising a step of drying to form a resist coating film made of the resist material on the substrate, wherein in the step of forming the resist coating film, while the substrate is rotating, the upper surface of the substrate A method for manufacturing a mask blank, characterized in that airflow is generated from the center of the substrate to the outer circumferential direction along the line, and the liquid reservoir of the resist liquid formed on the peripheral edge of the substrate is prevented from moving toward the center of the substrate by rotation of the substrate. It is described.

In Patent Document 3, a spraying step of spraying a resist liquid onto a mask substrate, a diffusion step of rotating the mask substrate while changing a rotation speed to diffuse the resist material over the entire mask substrate, and a resist film by rotating the mask substrate A method of manufacturing a blank mask, comprising: forming a film forming step; and a drying step of drying the resist film formed on the mask substrate by rotating the mask substrate at a lower rotational speed than the film forming step. . Patent Document 3 also describes that when spraying a resist material onto the mask substrate in the spraying step, the rotational speed of the mask substrate is set to 150 rpm or less, and the spraying time is set to a range of 1 to 10 seconds. In addition, Patent Literature 3 describes maintaining the rotational state of the substrate from the time when spraying of the resist material is finished to the time when the next diffusion step is started.

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. Hei 4-29215

Patent Document 2: Japanese Patent Laid-Open No. 2005-12851

Patent Document 3: Korean Patent Registration No. 10-0818674 Publication

Along with the miniaturization of the pattern size of the semiconductor wafer, the miniaturization of the pattern size of the transfer mask is gradually progressing. High sensitivity of the resist film of the mask blank used in the manufacture of a transfer mask is one of the requirements for finer patterns.

Chemically amplified resists are mentioned as a highly sensitive resist material. While chemically amplified resists are highly sensitive, their sensitivity is liable to change under the influence of various environments. For example, when a resist film is formed by a conventional method, the sensitivity distribution of the resist may occur on the substrate. The sensitivity distribution of the resist complicates the exposure conditions, making it difficult to refine the pattern size.

In view of the above circumstances, an object of the present invention is to provide a method for manufacturing a mask blank having a resist film having a small non-uniformity of the sensitivity distribution in the plane. It is also an object of the present invention to provide a method of manufacturing a transfer mask for obtaining a transfer mask having a fine pattern size.

As a cause of the non-uniformity of the resist sensitivity on the same substrate, it is possible to consider the influence of the action by environmental factors when the resist liquid is applied. Examples of environmental factors include the dry state of the resist liquid and physical actions such as centrifugal and frictional forces applied to resist molecules.

Among these physical actions, the present inventors have focused on the diffusion state of the resist liquid (the state of spreading the resist liquid in the dropping state) when the resist liquid is dropped onto the surface to which the resist liquid is applied (the surface to be coated). As a result, it was obtained that the faster the diffusion of the resist liquid onto the substrate, the smaller the non-uniformity in the sensitivity distribution. In addition, the inventors of the present invention have conducted various experiments and found that the non-uniformity of the sensitivity distribution in the surface of the resist film can be reduced by setting the rotation speed of the substrate to a predetermined value at the end of the dropping of the resist liquid. Arrived.

The present invention is a method of manufacturing a mask blank, characterized by the following configurations 1 to 11, and a method of manufacturing a transfer mask, characterized by the following configuration 12.

(Configuration 1)

The present invention is a method for manufacturing a mask blank comprising forming a resist film made of a resist material on a substrate, wherein the formation of the resist film is for dripping a resist liquid containing a resist material and a solvent onto the square-shaped substrate. Including a dropping process, and in the dropping process, when the rotation speed of the substrate at time t is R(t), the rotation speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid is It is a method of manufacturing a mask blank, which is 300 to 2000 rpm.

If the substrate is rotated at a high speed in the loading end time t _B, it is difficult to physical action exerted on the dropped resist solution (for example, the frictional force and the centrifugal force or the substrate), a uniform resist film becomes sensitivity distribution occurs. Time and results lower than the rotation speed of 300rpm in t _B, because the rotational speed is not enough, and is liable to variation in the physical effect to be applied to the dropped resist solution occurs. When it exceeds 2000 rpm, the physical action becomes uniform, but the resist dropped by the airflow caused by rotation starts to dry, and there arises a fear that the film thickness distribution deteriorates.

(Configuration 2)

In the manufacturing method of the mask blank of the present invention, it is preferable that the rotational speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid is 500 to 1000 rpm.

When R(t _B ) is between 500 and 1000 rpm, a mask blank with uniform film thickness and sensitivity can be further stabilized and manufactured.

(Configuration 3)

In the manufacturing method of the mask blank of the present invention, it is preferable to include a pre-dropping rotation step of rotating the substrate before starting to drop the resist liquid.

By including the rotation process before dropping, it is possible to stabilize the airflow of the substrate by rotation. By stabilizing the airflow of the substrate, the physical action applied to the resist liquid at the time of dropping becomes more uniform. As a result, the unevenness of the sensitivity distribution can be further eliminated. In addition, by including the rotation step before dropping, an additional effect of being able to remove foreign matter adhering on the substrate is obtained.

(Configuration 4)

In the method for manufacturing a mask blank of the present invention, after the dropping end time t _B of the resist liquid, the rotation speed R(t) of the substrate is adjusted to the rotation speed R(t) of the substrate at the dropping end time t _B of the resist liquid. _B ) or a drying degree adjustment step of stopping the rotation of the substrate, and after the drying degree adjustment step, the rotation speed R(t) of the substrate is adjusted to the substrate at the dropping end time t _B of the resist liquid. It is preferable to include a homogenization process which makes it higher than the rotational speed R(t _B ) of.

At the time point t _B , the resist liquid supplied onto the substrate tends to accumulate in the edge portion due to centrifugal force accompanying high-speed rotation. By performing a faster rotation than the rotation speed at the time t _B, it is the residue of the resist solution accumulated in the edge portion can be scattered in the lateral direction of the substrate. Thereby, the film thickness fluctuation is suppressed, and the variation in the sensitivity distribution resulting from the film thickness fluctuation can be suppressed.

(Configuration 5)

In the manufacturing method of the mask blank of the present invention, the rotational speed R(t) (t _B <t ≤ t _B +Δt) of the substrate during a predetermined time Δt immediately after the dropping end time t _B of the resist liquid is And a post-dropping rotation speed maintenance step of maintaining the same as the rotation speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid.

By maintaining the high-speed rotation of the substrate after the dropping step, the resist layer on the substrate can be thinned. In the case of manufacturing a mask blank for forming a pattern of fine dimensions in a resist film, this manufacturing method is particularly preferably applied.

(Configuration 6)

In the method for manufacturing a mask blank of the present invention, the exhaust means for exhausting the inside of the resist liquid coating apparatus can be operated after the dropping end time t _{B of the} resist liquid.

At the time point of the dropping end time t _B of the resist liquid, the resist layer formed on the substrate is in a fluid state by the solvent contained in the resist liquid. By activating the exhaust means at the dropping end time t _B , air flow toward the exhaust means in the resist liquid coating tank is generated, whereby the resist layer becomes uniform, and the film thickness can be made uniform.

(Configuration 7)

In the manufacturing method of the mask blank of the present invention, in at least a part of the homogenization step, the exhaust means for exhausting the inside of the resist liquid coating apparatus can be operated.

When the exhaust means is actuated, the atmospheric pressure in the resist liquid coating device is lowered, and thus the volatilization of the solvent component remaining in the resist layer is promoted. As a result, the resist layer dries quickly. As a result, suppression of the sensitivity distribution of the resist layer by distribution of the drying rate can be expected.

In addition, when the exhaust means is placed in a position where an airflow exiting the periphery of the resist substrate occurs when the exhaust means is actuated, the airflow acts so that the resist liquid accumulated in the periphery of the substrate is directed out of the substrate by spin rotation. . As a result, the phenomenon that the resist liquid accumulates in the periphery of the substrate is eliminated.

(Configuration 8)

In the method for manufacturing a mask blank of the present invention, the resist liquid may be a chemically amplified resist liquid.

Since the chemically amplified resist liquid is highly sensitive, a change in sensitivity is likely to occur. This manufacturing method is particularly suitable for a manufacturing method of a mask blank manufactured using a highly sensitive chemically amplified resist.

(Configuration 9)

In the manufacturing method of the mask blank of the present invention, the surface forming the resist film of the substrate is a surface of a thin film formed by a reactive sputtering method, and the thin film is at least Cr, Ta, Si, Mo, Ti, V, Nb and W. It may contain one or more elements selected from the group consisting of.

A thin film containing the material deposited by sputtering has high activity. For this reason, when the resist liquid comes into contact with the thin film, a change in sensitivity is likely to occur. This manufacturing method can minimize the unevenness of the sensitivity distribution that occurs when the resist is dropped. Therefore, even a substrate on which a thin film having a structure in which sensitivity change is likely to occur can be effectively suppressed from unevenness in the sensitivity distribution.

(Configuration 10)

In the method of manufacturing a mask blank of the present invention, the thin film may contain at least Cr, and the ratio of Cr contained in the thin film may be at least 50 atomic% or more.

On the surface of a thin film containing Cr, chromium oxide in which Cr and oxygen in the environment are bonded is exposed. Cr oxide has low surface energy. In a thin film having a Cr concentration exceeding atomic%, the wettability with the resist liquid deteriorates because the exposure ratio of the Cr oxide having low surface energy increases.

The manufacturing method of the mask blank of the present invention can exhibit particularly excellent effects when forming a resist layer on a thin film having such a configuration.

(Composition 11)

In the method for manufacturing a mask blank of the present invention, the thin film may contain at least Si.

The composite film made of Si and other elements, particularly metal elements, has a lower surface energy compared to the case where the composite film is not a composite film with Si.

Accordingly, the method for manufacturing a mask blank of the present invention can exhibit particularly excellent effects when forming a resist layer on a thin film having such a configuration.

(Composition 12)

In the present invention, a resist pattern is formed by patterning the resist film of a mask blank manufactured by the method for manufacturing a mask blank according to any one of configurations 1 to 11, and a mask pattern is formed using the resist pattern as a mask. It is a method of manufacturing a transfer mask, characterized in that to manufacture.

According to the present invention, it is possible to obtain a method for manufacturing a mask blank having a resist film having a small non-uniformity in the in-plane sensitivity distribution. Further, by using the mask blank obtained by the method for producing a mask blank of the present invention, a method for producing a transfer mask for producing a transfer mask having a fine pattern size can be obtained.

1 is a diagram showing the relationship between the time of each step during the resist coating step and the rotational speed of the substrate.
2 is a flowchart showing an example of the procedure of a resist coating process.
3 is a schematic side cross-sectional view showing an example of a resist liquid coating device (rotating coating device).
4 is a schematic diagram showing an example of (A) a substrate with a thin film, (B) a mask blank, and (C) a mask for transfer.
Fig. 5 is a schematic cross-sectional view showing an example of a mask blank provided with a light shielding film and an etching mask film on a substrate.

When manufacturing a mask blank for manufacturing a transfer mask, a resist film is formed on a substrate or on a substrate with a thin film having a thin film formed on the substrate to prepare a mask blank. In this specification, a process of forming a resist film by applying a resist liquid on a substrate or on a substrate (a substrate with a thin film) on which a predetermined thin film is formed is referred to as a "resist coating process". In addition, in this specification, a substrate on which a thin film is not formed and a substrate with a thin film are collectively referred to as simply "substrate" in some cases.

In the method of manufacturing a mask blank of the present invention, in the dropping step (S2) for dropping the resist liquid during the resist coating step, when the rotation speed of the substrate at time t is R(t), the resist liquid is It is characterized in that the rotational speed R(t _B ) of the substrate at the dropping end time t _B is set to 300 to 2000 rpm. According to the manufacturing method of the mask blank of the present invention, it is possible to reduce the unevenness of the sensitivity distribution of the formed resist film.

Further, as a mechanism capable of reducing the unevenness of the sensitivity distribution of the resist film according to the present invention, the following can be considered. That is, by dropping the resist liquid onto the substrate rotating at a predetermined rotational speed, a substantially homogeneous physical action (e.g., the dry state of the resist liquid, the centrifugal force applied to the resist molecules, the frictional force, etc.) is applied to the resist liquid. All. For this reason, since the sensitivity of the resist film formed in the resist coating step can be made uniform, it can be assumed that the unevenness of the sensitivity distribution of the formed resist film can be reduced. However, this invention is not limited to this guess.

In the manufacturing method of the mask blank 10 of the present invention, first, a substrate 15 with a thin film in which a predetermined thin film 14 is formed on the surface of the substrate 11 is prepared (FIG. 4A). Subsequently, a resist liquid 26 is applied dropwise to the surface of the thin film 14 of the thin film-attached substrate 15 by a predetermined method, and the resist film 16 is formed to prepare the mask blank 10 of the present invention. It can be done (Fig. 4(B)). By performing predetermined patterning on the thin film 14 of the mask blank 10 of the present invention, a transfer mask 18 having a mask pattern 13 for transferring to a transfer object can be manufactured (Fig. 4). (C)).

As the substrate 11 used in the manufacturing method of the mask blank 10 of the present invention, a glass substrate can be used. The glass substrate is not particularly limited as long as it is used as the mask blank 10. For example, synthetic quartz glass, soda lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass, etc. are mentioned. In the case of a glass substrate for reflective mask blanks (for EUV mask blanks), in order to suppress distortion of the pattern to be transferred due to heat during exposure, within the range of about 0±1.0×10 ^-7 /°C, more preferably Preferably, a glass material having a low coefficient of thermal expansion in the range of about 0±0.3×10 ^-7 /°C is used. In addition, since a large number of thin films are formed on the glass substrate for the EUV mask blank, a glass material having high rigidity capable of suppressing deformation due to film stress is used. As the substrate 11, a glass material having a high Young's modulus of 65 GPa or more is particularly preferable. For example, amorphous glass such as SiO ₂ -TiO _{2 type} glass or synthetic quartz glass, or crystallized glass in which a β-quartz solid solution has been deposited is used.

It is preferable that the shape of the substrate 11 used in the manufacturing method of the mask blank 10 of the present invention is a square shape. In general, it is not easy to uniformly apply the resist liquid 26 even to the edge portions of the substrate 11. On the other hand, if the method for manufacturing the mask blank 10 of the present invention is used, the resist liquid 26 can be uniformly applied even to the edge of the substrate 11, so that the resist film ( 16) can be obtained.

The thin-film substrate 15 used in the manufacturing method of the mask blank 10 of the present invention is a thin film 14 formed on the main surface of the square-shaped substrate 11 using a sputtering method, a vapor deposition method, or a CVD method. It can be manufactured by doing.

The thin film 14 causes an optical change with respect to exposure light (for example, an ArF excimer laser, etc.), and specifically, a light-shielding film that blocks exposure light, or a phase shift film that changes the phase of exposure light (this phase shift film Examples include a halftone film having a light-shielding function and a phase shift function), a multilayer reflective film used for a reflective mask blank, an absorber, and a thin film having a laminated structure comprising an etching mask.

The thin film 14 of the phase shift mask blank and the binary mask blank is not limited to a single layer, and a laminated film in which a plurality of layers such as an etching stopper layer or an etching mask layer are stacked may be used in addition to the light shielding film and the phase shift film described above. As the laminated film of the thin film 14, for example, a laminated film of a light-shielding film and a laminated film of a phase shift film and a light-shielding film may be mentioned.

Multilayer reflective film is a multilayer reflective film applicable to EUV light, Si/Ru cycle multilayer film, Be/Mo cycle multilayer film, Si compound/Mo compound cycle multilayer film, Si/Nb cycle multilayer film, Si/Mo/Ru cycle multilayer film, Si/Mo/ Ru/Mo periodic multilayer film and Si/Ru/Mo/Ru periodic multilayer film, etc. are mentioned. An absorber layer made of a Ta-based material or the like is formed on the surface of the multilayer reflective film, and an etching mask film made of a Cr-based compound is formed thereon.

As the mask blank 10 which can be manufactured by the manufacturing method of the mask blank 10 of this invention, a binary mask blank, a phase shift type mask blank, and a reflection type mask blank are mentioned. In the case of a binary mask blank and a phase shift type mask blank, a light-transmitting substrate made of synthetic quartz glass is used as the substrate 11. As the binary mask blank, a mask blank in which a light-shielding film is formed as the thin film 14 is exemplified, and as the phase shift mask blank, a mask blank in which a phase shift film (including a halftone film) is formed as the thin film 14 is exemplified.

In the case of a reflective mask blank, a low thermal expansion glass (SiO2-TiO2 glass, etc.) having a small coefficient of thermal expansion is used as the substrate 11, and on the substrate 11 a light reflective multilayer film and a mask pattern 13 The light absorber film to be formed is sequentially formed. In the case of a reflective mask blank, these light reflective multilayer films, light absorber films, and etching mask films are the thin films 14.

The manufacturing method of the mask blank 10 of the present invention includes a resist coating step for forming a resist film 16 made of a resist material on the substrate 11 (substrate 15 with a thin film). Further, in the manufacturing method of the mask blank 10 of the present invention, it is possible to form the resist film 16 directly on the substrate 11. However, in general, since the resist film 16 is formed on the surface of the thin film-attached substrate 15, the following describes the form of applying the resist liquid 26 to the surface of the thin film 14 of the thin-film-attached substrate 15. Explain. However, in this specification, for example, the "substrate 15 with a thin film" may be simply referred to as a "substrate". In particular, the "rotation speed of the substrate" and the "rotation speed of the thin-film-attached substrate 15" both represent the rotational speed of the resist liquid coating device (rotation coating device) 20, and therefore both have the same meaning.

1 shows the relationship between the time of each step of the resist coating step of the manufacturing method of the present invention and the rotational speed of the thin film-attached substrate 15. In addition, Fig. 2 is a flowchart showing an example of the procedure of the resist coating step of the manufacturing method of the present invention. 3 shows an example of a resist liquid coating device 20, which is a resist liquid coating device for forming a resist film 16 by applying a resist liquid 26 to the surface of the thin film 14 of the thin film 15 It shows a schematic cross-sectional side view.

A resist coating step in the method for manufacturing the mask blank 10 of the present invention will be described with reference to FIGS. 1, 2 and 3. As shown in Fig. 2, the resist application step in the method for manufacturing the mask blank 10 of the present invention includes a dropping step (S2). In addition, the resist coating step in the manufacturing method of the mask blank 10 of the present invention includes a post-dropping rotation speed maintenance step (S3), a drying degree adjustment step (S4), a homogenization step (S5), and a drying step (S6). It can be included as needed. In addition, the resist coating step may further include a rotation step (S1) before dropping before the dropping step (S2). The rotation process before dropping (S1) may include an acceleration step (S1a) and a constant speed step (S1b) as necessary.

As shown in Fig. 3, the resist liquid coating device 20 is a spinner chuck that mounts, for example, a thin-film-attached substrate 15 on which a light-shielding film is formed on a square-shaped substrate 11 to be rotatable. 21), a nozzle 22 for dropping the resist liquid 26 onto the thin film-attached substrate 15, and the dropped resist liquid 26 are rotated by the thin-film-attached substrate 15 ) After scattering to the outside, a cup 23 for preventing scattering around the resist liquid application device 20, and a resist liquid scattered above the cup 23 to the outside of the thin film-attached substrate 15 ( An inner ring 24 for guiding 26 to an outer lower side of the cup 23 and an exhaust means 30 for exhausting air to generate an air flow 34 toward the thin film-attached substrate 15 are provided.

A motor (not shown) for rotating the thin film-attached substrate 15 is connected to the spinner chuck 21 described above, and this motor rotates the spinner chuck 21 based on a rotation condition described later.

Further, below the cup 23, an exhaust means 30 provided with an exhaust amount control means for controlling the exhaust amount, and a draining means for recovering and draining the resist liquid 26 scattered outside the thin film-attached substrate 15 during rotation. (Not shown) is installed.

In the resist coating process using the resist liquid coating device 20, the substrate 15 with a thin film is initially transferred to the spinner chuck 21 of the resist liquid coating device 20 by a substrate transfer device (not shown). , The substrate 15 with a thin film is held on the spinner chuck 21.

The resist coating step is followed by a dropping step (S2) for dropping the resist liquid 26 containing a resist material and a solvent onto the rectangular-shaped thin-film substrate 15 as shown in Figs. 1 and 2. Include. Specifically, the resist liquid 26 is dripped onto the surface of the thin film 14 of the thin film-attached substrate 15 from the nozzle 22 of the resist liquid coating device 20.

The dropping step (S2) includes a rotation acceleration step (S1) in which the rotational speed of the thin film-attached substrate 15 rapidly changes. In the manufacturing method of the mask blank 10 of the present invention, the resist liquid 26 is rotated at a predetermined rotational speed through the spinner chuck 21 by a motor during the dropping step (S2). Dripping. Specifically, in the present invention, in the dropping step (S2), when the rotation speed of the substrate at the time t is R(t), the rotation speed of the substrate at the dropping end time t _B of the resist liquid 26 It is characterized in that R(t _B ) is 300 to 2000 rpm, preferably 500 to 1000 rpm.

In addition, if the rotational speed of the substrate at the dropping end time t _B of the resist liquid 26 is less than 300 rpm, there is a concern that non-uniformity in the sensitivity distribution may occur. Further, when the rotation speed of the substrate at the time t _B is 500 rpm or more, the non-uniformity of the sensitivity distribution can be made smaller.

In addition, if the rotational speed of the substrate at the dropping end time t _B of the resist liquid 26 is 2000 rpm or more, volatilization of the solvent component of the resist liquid 26 is promoted by high-speed rotation, and during the dropping step (S2) There is a fear that a part of the resist liquid 26 will be dried. Time the rotational speed of the substrate when the t _B can be made smaller than the risk of drying is less than 1000rpm, the resist solution 26.

The rotational speed of the substrate at the dropping start time t _A of the resist liquid 26 is not particularly limited. However, in order to realize smooth application of the resist liquid 26 to the substrate, the rotation speed R(t _A ) of the substrate at the dropping start time t _{A of the} resist liquid 26 and the dripping of the resist liquid 26 It is preferable that the rotational speed R(t _B ) of the substrate at the end time t _B satisfies the relationship of R(t _A )≦R(t _B ). In addition, in order to realize more smooth application of the resist liquid 26 to the substrate, it is desirable to maintain the same rotational speed from the dropping start time t _A of the resist liquid 26 to the dropping end time t _B. Further, immediately after the dropping start time t _A of the resist liquid 26, within a short time, for example, within 0.1 seconds, preferably within 0.07 seconds, the rotational speed R(t) of the substrate at the dropping end time t _B of the resist liquid 26 _B) accelerate the rotational speed of the substrate up to, and then it is desirable to maintain the rotational speed R (t _B).

In addition, "maintaining the same rotational speed" means that the rotational speed is basically the same. However, when "maintaining the same rotational speed", fluctuations in rotational speed to a degree that do not adversely affect the application of the resist liquid 26 by the method of the present invention, for example, fluctuations in rotational speed of ±30%, are preferable. Preferably, it may include a variation of the rotational speed of ±20%, more preferably a variation of the rotational speed of ±10%, and more preferably a variation of the rotational speed of ±5%.

With reference to Figs. 1 and 2, a preferred embodiment will be described with respect to a resist coating step in the method for manufacturing the mask blank 10 of the present invention.

In the manufacturing method of the mask blank 10 of the present invention, the resist application step may include a rotation step (S1) before dropping. In the rotation process before dropping (S1), it is a step of rotating the substrate 15 with a thin film before the dropping start time t _A of the resist liquid 26. The rotation process before dropping (S1) includes an acceleration step (S1a) for accelerating the rotational speed of the substrate from a stationary state to a predetermined rotational speed, and a constant speed step (S1b) for maintaining the rotational speed of the substrate at a predetermined rotational speed. can do.

By accelerating the rotational speed of the substrate with a predetermined rotational acceleration from a stationary state to a predetermined rotational speed by a pre-loading rotation process (S1) that properly includes an acceleration step (S1a) and a constant speed step (S1b), the rotation start is initiated. The disturbance of the airflow 34 in the vicinity of the substrate can be reduced or eliminated before the dropping start time t _A is reached. As a result, in the dropping of the resist liquid 26 in the dropping step (S2) following the pre-dropping rotation step (S1), coating unevenness due to disturbance of the airflow 34 (due to the non-uniformity of the application of the resist liquid 26) Pattern) becomes difficult to occur. Further, by rotation of the substrate in the rotation step S1 before dropping, foreign matter adhering to the substrate surface may be reduced.

The rotational acceleration in the acceleration step S1a is not particularly limited. To ensure reduction of foreign matter adhering to the substrate surface and to ensure that the occurrence of coating unevenness due to disturbance of the airflow 34 when the resist liquid 26 is dropped in the dropping step (S2) is reduced. , The rotational acceleration in the acceleration step (S1a) may be 100 to 2000 rpm/sec, preferably 200 to 1500 rpm/sec. In addition, the rotational speed of the constant speed step (S1b) may be 200 to 1500 rpm, preferably 500 to 1000 rpm.

In the manufacturing method of the mask blank 10 of the present invention, the resist coating step is performed immediately after the dropping end time t _B of the resist liquid 26, during a predetermined time Δt, the rotational speed R(t)(t _B ) of the substrate. <t≤t _B +Δt) may further include a post-dropping rotational speed maintenance step (S3) for maintaining the same as the rotational speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid 26. have. By maintaining the same rotational speed of the substrate even after the dropping of the resist liquid 26 is finished, the resist liquid 26 dropped immediately before the dropping is also expanded to the substrate surface by the same centrifugal force as the resist liquid 26 immediately after dropping starts. I can. Therefore, the resist liquid 26 can be sufficiently expanded on the surface of the substrate. Further, the predetermined time Δt is preferably 0.5 to 10 seconds, and more preferably 2 to 5 seconds.

In the manufacturing method of the mask blank 10 of the present invention, the resist coating step is after the dropping end time t _B of the resist liquid 26, that is, after the dropping step (S2), or after the dropping step (S2). If there is a rotational speed maintaining step (S3) after dropping in, then, a drying degree adjusting step (S4) of lowering the rotational speed of the substrate or stopping rotation may be further included.

When dropping is performed at high speed rotation in the dropping step (S2), the solvent component volatilizes from the resist liquid 26 moistened on the substrate during the dropping step (S2). Therefore, a difference occurs in the wet state in the vicinity of the region on the substrate facing the nozzle 22 to which the resist liquid 26 is dropped, and in the region on the substrate around it. By reducing or stopping the rotational speed of the substrate by the drying degree adjustment step (S4), the resist liquid is relatively gentle toward the entire surface of the substrate while suppressing the volatilization of the solvent component contained in the resist liquid 26 applied to the substrate. (26) Spreads and can prevent partial wet and dry bias. Further, by providing the drying degree adjustment step (S4), homogenization of the resist film 16 reliably proceeds also in the homogenization step (S5). In addition, since the dry and wet bias of the applied resist liquid 26 is temporarily eliminated in the drying degree adjustment step (S4), the change in sensitivity of the resist film 16 due to the difference in the drying speed of the resist liquid 26 is also suppressed. can do.

In the manufacturing method of the mask blank 10 of the present invention, the resist application step is, after the dropping step (S2), at a rotation speed of the substrate faster than the rotation speed R(t _B ) of the substrate at the dropping end time t _B. It may include a homogenization process (S5) rotating the substrate. When the resist coating process has the uniforming process (S5), the film thickness of the resist film 16 on the thin film-attached substrate 15 can be made uniform. When the resist application process includes the rest process (S3) and the pre-rotation process (S4 and S5), the homogenization process (S5) is performed after those processes (S3 to S5). The rotation speed and rotation time of the substrate in the homogenization step S5 can be set according to the type of the resist liquid 26. In general, it is preferable that the rotation speed of the substrate in the homogenization step (S5) is 850 to 2000 rpm, and the rotation time is 1 to 15 seconds.

In the manufacturing method of the mask blank 10 of the present invention, in the homogenization step (S5), the exhaust means 30 for evacuating to generate an airflow 34 toward the thin film-attached substrate 15 is operated. It is preferable to include that. When the application environment is actively depressurized in the dropping step (S2), the phenomenon that the resist liquid 26 is dried before it comes into close contact with the surface to be coated, or the resist liquid 26 is dried and agglomerated in a state in which foreign substances are mixed is suppressed. can do.

In the manufacturing method of the mask blank 10 of the present invention, the resist application process may include a drying process (S6). In the drying step (S6), the uniformity of the film thickness of the resist film 16 obtained by the homogenizing step (S5) by rotating the substrate 15 with a thin film at a lower rotation speed than the rotation speed in the homogenizing step (S5) While maintaining the resist film 16 can be dried. The rotational speed of the substrate in the drying step (S6) is 500 rpm or less, preferably 150 to 350 rpm, and the duration is not particularly limited, and is preferably performed until the resist film 16 is dried. The duration of the drying step (S6) may be specifically 5 seconds or more, and preferably 10 to 60 seconds.

In the manufacturing method of the mask blank 10 of the present invention, it is preferable to operate the exhaust means 30 for exhausting the inside of the resist liquid coating apparatus after the dropping end time t _B of the resist liquid 26. Specifically, after the dropping step (S2) is finished, the substrate 15 with the thin film is rotated by the exhaust means 30 provided with the exhaust amount control means for controlling the exhaust amount. The air flow 34 may be generated so that the air flow 34 flows from the center of the thin film-attached substrate 15 along the upper surface in the outer circumferential direction. When the exhaust means 30 is operated, an air flow 34 is generated from the inside of the resist liquid coating device toward the exhaust means 30. If the airflow 34 is generated before the resist liquid 26 extends to the entire surface of the substrate, drying of the location where the airflow 34 flows is accelerated and coating unevenness (a pattern caused by the non-uniformity of the application of the resist liquid 26) Cause of. Therefore, it is preferable to perform the operation of the exhaust means 30 after completion of the dropping step (S2) in which the resist liquid 26 is sufficiently expanded on the substrate surface.

Further, when the exhaust means 30 for exhausting the inside of the resist liquid coating device is operated, the resist generated on the outer periphery of the thin film-attached substrate 15 (the main surface end of the substrate 11) by the air flow 34 The liquid reservoir of the liquid 26 can be effectively scattered out of the thin film-attached substrate 15. Further, it is possible to effectively suppress the liquid accumulation of the resist liquid 26 generated at the four corners of the thin film-attached substrate 15 or the outer circumference of the thin-film-attached substrate 15 from returning to the central portion of the thin-film-attached substrate 15. As a result, it is possible to reduce the thick film regions (regions with a thick film thickness) of the resist film 16 formed at the four corners and the periphery of the thin film-attached substrate 15, or reduce the swelling of the film thickness in the region ( It can suppress thickening). Specifically, it is preferable to control the amount of exhaust so that the velocity of the airflow 34 reaching the upper surface of the thin film-attached substrate 15 is 0.5 m/sec or more and 5 m/sec or less.

In addition, by controlling the height (distance) to the inner ring 24 (opening portion 32) provided on the upper surface of the substrate 15 with the thin film and above the cup 23 and the opening diameter of the inner ring 24, thin film adhesion It is possible to control the flow velocity of the airflow 34 from the upper surface of the substrate 15 to the outer peripheral portion of the substrate 15 with a thin film. As a result, the liquid reservoir of the resist liquid 26 generated on the outer periphery of the thin film-attached substrate 15 (the main surface end of the substrate 11) is effectively scattered out of the thin-film-attached substrate 15, or the thin-film-attached substrate 15 It is possible to maintain the flow rate necessary to effectively suppress the liquid accumulation of the resist liquid 26 generated at the four corners of the thin film or the outer circumference of the thin-film-attached substrate 15 from being returned to the central portion of the thin-film-attached substrate 15.

In addition, the generation of the airflow 34 by the exhaust means 30 is in synchronization with a predetermined high-speed rotation speed of the substrate in at least a part of the homogenization process (S5), preferably all of the homogenization process (S5). It is preferable to operate the exhaust means 30 for exhausting the inside of the liquid application device. In addition, generation of the airflow 34 by the exhaust means 30 can be performed not only in the homogenization step (S5) but also in other steps, for example, the drying step (S6).

In the manufacturing method of the mask blank 10 of the present invention, in order to completely evaporate the solvent contained in the resist film 16 formed on the thin film-attached substrate 15 after completion of the above-described drying step (S6), this resist film (16) You may have a heat drying process of heating and drying treatment. This heat-drying treatment step is usually a heating step of heating the substrate 15 with the resist film 16 formed thereon by a heating plate, and the substrate 15 with the thin film having the resist film 16 formed on the cooling plate. It includes a cooling process to cool by. The heating temperature and time in these heating steps, and the cooling temperature and time in the cooling step can be appropriately adjusted according to the type of resist liquid 26.

In the manufacturing method of the mask blank 10 of the present invention, the resist liquid 26 is not particularly limited, but a chemically amplified resist is preferably used because a predetermined sensitivity can be obtained. In addition, as the resist liquid 26, specifically, a polymer-type resist made of a high molecular weight resin having a viscosity exceeding 10 mPa·s and an average molecular weight of 100,000 or more, or a polymer type resist having a viscosity of less than 10 mPa·s and an average molecular weight of 100,000 It is possible to use a novolac-based resist composed of less than a novolac resin and a dissolution decontaminant, or a chemically amplified resist composed of a polyhydroxystyrene-based resin and an acid generator. In particular, what is effective in this embodiment is a resist having a viscosity of less than 10 mPa·s and an average molecular weight of less than 100,000. In addition, in the case of a resist made of a plurality of constituent materials including a polymer, a photo acid generator (PAG), and a quencher, such as a chemically amplified resist, the surface of the constituent material within the surface of the mask blank 10 Due to the occurrence of in-plane deviation, in-plane CD deviation is likely to occur.

For example, since the viscosity of chemically amplified resists or novolac-based resists is low (10 mPa·s or less), in the homogenization process (S5), the rotation speed of the substrate is 850 to 2000 rpm, and the rotation time of the substrate 11 is 1 To 10 seconds, respectively, and in the drying process (S6), the rotation speed of the substrate is set to 100 to 450 rpm. In addition, since the polymer resist has high viscosity (more than 10 mPa·s), in the homogenization process (S5), the rotation speed of the substrate is set to 850 to 2000 rpm, and the rotation time of the substrate 11 is set to 2 to 15 seconds, respectively, and drying. In step (S6), the rotational speed of the substrate 11 is set to 50 to 450 rpm. The rotation time of the substrate 11 in the drying step (S6) is until the resist film 16 is completely dried (when the film thickness of the resist film 16 does not decrease even if the drying rotation is continued for a longer time). Until) the required time is set.

It is preferable that the final discharge amount of the resist liquid 26 in the resist coating step is 1.5 to 8 ml. If it is less than 1.5 ml, there is a fear that the resist liquid does not spread widely enough on the substrate surface and the film-forming state is deteriorated. If it exceeds 8 ml, the amount of the resist liquid not used for coating and scattering outward by spin rotation increases, and the consumption of the resist liquid increases, which is not preferable. In addition, there is a concern that the scattered resist liquid may contaminate the interior of the coating apparatus.

In addition, it is preferable that the discharge rate of the resist liquid 26 is 0.5 to 3 ml/sec. If the discharge rate is less than 0.5 ml/sec, there arises a problem that the time for supplying the resist liquid onto the substrate becomes longer. If the discharge rate exceeds 3 ml/sec, the resist liquid strongly contacts the substrate and repels it, which is not preferable because there is a possibility that the resist liquid will be bounced off without wet the substrate.

In the manufacturing method of the mask blank 10 of the present invention, the surface forming the resist film 16 of the thin film-attached substrate 15 is the surface of the thin film 14 formed by the reactive sputtering method, and the thin film 14 is at least It is preferable to contain at least one element selected from the group consisting of Cr, Ta, Si, Mo, Ti, V, Nb and W. Since the resist liquid has poor wettability with the surface of the thin film 14 containing these elements, when the resist liquid 26 is dropped onto the surface of the thin film-attached substrate 15 (the surface of the thin film 14), the resist liquid 26 ) Is particularly easy to bounce. The resist liquid 26 can prevent the resist liquid 26 from being bounced off the surface of the thin film 14 by using the manufacturing method of the mask blank 10 of the present invention, so that the resist liquid 26 14) It is possible to prevent non-uniformity of the in-plane sensitivity distribution of the resist film 16 due to a physical impact caused by being bounced on the surface.

In the manufacturing method of the mask blank 10 of the present invention, the thin film 14 having a surface (coated surface) forming the resist film 16 contains at least Cr, and the ratio of Cr contained in the thin film 14 is It is preferably at least 50 atomic% or more. When the surface to be coated is a thin film containing Cr, for example, CrN, CrON, CrOC, CrOCN, etc., since the wettability of the surface to be coated with respect to the resist liquid 26 is poor, the resist initially dropped on the surface of the thin film 14 The liquid 26 is easy to bounce (bounce) as a droplet. When the method for manufacturing the mask blank 10 of the present invention is used, even when the surface to be coated is a thin film containing Cr, the resist liquid 26 is caused by physical impact due to being bounced on the surface of the thin film 14, Non-uniformity in the in-plane sensitivity distribution of the resist film 16 can be prevented.

In addition, as shown in FIG. 5, the thin film containing Cr is provided as the etching mask film 3 on the upper surface of the light-shielding film 2 in some cases. The etching mask film 3 contains at least one component of nitrogen and oxygen in chromium, and the chromium content in the etching mask film 3 is 50 atomic% or more. As shown in FIG. 5, such a mask blank 10 includes a light-shielding film 2 on a light-transmitting substrate 11, and a mask blank provided with an etching mask film 3 on the light-shielding film 2 ( 10) can be.

In the example shown in Fig. 5, the etching mask film 3 is made of, for example, chromium so as to ensure etching selectivity with the light-shielding film 2 for dry etching during patterning for forming a transfer pattern. It is preferable to use a material containing at least one of nitrogen and oxygen. By providing such an etching mask film 3 on the light shielding film 2, the resist film 16 formed on the mask blank 10 can be thinned. Further, a component such as carbon may be further included in the etching mask film 3. Specifically, materials, such as CrN, CrON, CrOC, and CrOCN, are mentioned, for example.

In recent years, a method of exposing a design pattern by applying an electron beam drawing exposure resist to the resist film 16 and irradiating an electron beam to draw (electron beam exposure drawing) has been used. In this electron beam drawing exposure, at least one of the light shielding film 2 and the etching mask film 3 needs a certain degree of conductivity from the viewpoint of drawing position accuracy and charge-up. That is, it is desired that at least one of the light-shielding film 2 and the etching mask film 3 has a sheet resistance value of 1.0×10 ⁶ Ω/□ or less.

When the sheet resistance value of the light shielding film 2 is 1.0×10 ⁶ Ω/□ or less, the etching mask film 3 can draw electron beams without causing charge-up even if the sheet resistance value is high. For thinning of the resist film 16, it is more preferable to improve the etching rate of the dry etching of the etching mask film 3 with a mixed gas of chlorine and oxygen. For that purpose, the content of the metal component (chromium) is preferably less than 50 atomic%, preferably 45 atomic% or less, and further preferably 40 atomic% or less.

On the other hand, when the sheet resistance value of the light-shielding film 2 is greater than 1.0×10 ⁶ Ω/□, the sheet resistance value of the etching mask film 3 needs to be 1.0×10 ⁶ Ω/□ or less. In this case, when the etching mask film 3 has a single layer structure, the chromium content in the etching mask film 3 is preferably 50 atomic% or more, and more preferably 60 atomic% or more. In the case where the etching mask film 3 has a multilayered structure, at least the chromium content of the layer on the side in contact with the resist film 16 is 50 atomic% or more (preferably 60 atomic% or more), and the light shielding film The chromium content of the layer on the side (2) is preferably less than 50 atomic% (preferably 45 atomic% or less, further 40 atomic% or less). In addition, the etching mask film 3 is a side in contact with the resist film 16 from the light-shielding film 2 side (however, except for the surface layer in contact with the resist film 16 in which a decrease in chromium content due to surface oxidation cannot be avoided). A composition gradient structure in which the chromium content increases toward) may be used. In this case, it is less than 50 atomic% (preferably 45 atomic% or less, further 40 atomic% or less) where the chromium content of the etching mask film 3 is the lowest, and 50 atomic% or more ( It is preferably 60 atomic% or more).

Further, it is preferable that the etching mask film 3 has a thickness of 5 nm or more and 20 nm or less. If the film thickness is less than 5 nm, film reduction in the pattern edge direction of the etching mask film 3 proceeds before dry etching of the light shielding film 2 is completed using the etching mask film 3 pattern as a mask, and the light shielding film ( There is a fear that the CD accuracy of the pattern transferred to 2) with respect to the design pattern may be significantly reduced. On the other hand, if the film thickness is thicker than 20 nm, the film thickness of the resist film 16 required for transferring the design pattern to the etching mask film 3 becomes thick, and the fine pattern is transferred to the etching mask film 3 with high precision. It becomes difficult to do.

When the method for manufacturing the mask blank 10 of the present invention is used, even when the surface to be coated is the resist liquid 26 as described above and the etching mask film 3 containing Cr having poor wettability, the resist liquid 26 ), it is possible to prevent non-uniformity in the in-plane sensitivity distribution of the resist film 16 due to a physical impact caused by bounce (bounce) of droplets of ).

In the manufacturing method of the mask blank 10 of the present invention, it is preferable that the thin film 14 having a surface to be coated contains at least Si. Since the surface energy of the surface of the thin film 14 containing Si is lower than the surface energy of the surface of the thin film containing Cr, the resist liquid 26 is applied to the surface of the substrate 15 with a thin film (the surface of the thin film 14). ), it is particularly easy to repel the resist liquid 26 when it is dropped on. Using the method of manufacturing the mask blank 10 of the present invention, even when the thin film 14 containing silicon is the surface to be coated, the resist liquid 26 can be prevented from being bounced off the surface of the thin film 14. Therefore, a desirable resist film 16 can be formed.

As the material of the thin film 14 containing Si, for example, MoSi, MoSiO, MoSiN, MoSiON, Si alone, SiO, SiN, SiON, WSi, TaSi, and the like can be mentioned.

In the manufacturing method of the mask blank 10 of the present invention, the thin film 14 having the surface to be coated is formed by predetermined etching with the light shielding film 2 made of a metal or metal compound that can be etched by fluorine-based dry etching, and the light shielding film 2 It may be a laminated film with the etching mask film 3 made of a material having a selectivity.

As the light shielding film 2 made of a metal or a metal compound that can be etched by fluorine-based dry etching, a silicon-containing material can be mentioned, for example. In that case, a material containing chromium may be mentioned as a material having a predetermined etching selectivity with the light shielding film 2. Examples of the chromium-containing material include chromium alone or a chromium compound containing chromium and at least one selected from oxygen, nitrogen and carbon. In addition, it is preferable that the material does not contain silicon. Specifically, examples of the chromium compound include chromium oxide, chromium nitride, chromium oxynitride, chromium oxide carbide, chromium nitride carbide, or chromium oxynitride carbide. It is known that these materials have high resistance to fluorine-based dry etching.

When the chromium content of the chromium-containing material is 50 atomic% or more, particularly 60 atomic% or more, the fluorine-based dry etching resistance is good, and sufficient etching selectivity can be provided for the light shielding film 2 and/or the transparent substrate 11 At the same time, it is preferable because the pattern can be formed by dry etching the etching mask film 3 under dry etching conditions containing chlorine and oxygen.

As a material containing chromium, for example, chromium is 50 atomic% or more and 100 atomic% or less, particularly 60 atomic% or more and 100 atomic% or less, oxygen is 0 atomic% or more and 50 atomic% or less, particularly 0 atomic% or more and 40 atomic% Hereinafter, when nitrogen is 0 atomic% or more and 50 atomic% or less, particularly 0 atomic% or more and 40 atomic% or less, and carbon is 0 atomic% or more and 20 atomic% or less, particularly 0 atomic% or more and 10 atomic% or less, the etching mask film ( As 3), the light shielding film 2 and/or the thin film 14 providing sufficient etching selectivity to the transparent substrate can be used.

When the method for manufacturing the mask blank 10 of the present invention is used, even when the surface to be coated is the etching mask film 3 containing Cr having poor wettability of the resist liquid 26 as described above, the resist liquid 26 ), it is possible to prevent non-uniformity in the in-plane sensitivity distribution of the resist film 16 due to a physical impact caused by bounce (bounce) of droplets of ).

As described above, the manufacturing method of the mask blank 10 of the present invention is a sputtering method of the thin film 14 serving as the mask pattern 13 for transferring to the object to be transferred on the main surface of the square-shaped substrate 11 A film is formed using a vapor deposition method, a CVD method, or the like, and a resist film 16 is formed on the surface of the thin film 14 of the thin film-attached substrate 15 by a resist coating process to manufacture the mask blank 10.

Further, the mask blank 10 has a mask pattern formation region in the center region of the thin film 14 of the thin film-attached substrate 15. In this mask pattern formation region, when the thin film-attached substrate 15 is patterned to form a transfer mask 18, a mask pattern 13 for transferring and forming a circuit pattern of a transfer object such as a semiconductor substrate is formed. Area. This mask pattern formation region differs depending on the size of the mask blank 10, but for example, when the mask blank 10 has a size of 152 mm x 152 mm, the thin film 14 of the thin film substrate 15 is It is an area of 132mm x 132mm in the center.

In the present invention, the resist film 16 of the mask blank 10 manufactured by the manufacturing method of the mask blank 10 is patterned to form a resist pattern, and the mask pattern 13 is formed using the resist pattern as a mask. It is a method of manufacturing the transfer mask 18, characterized in that the transfer mask 18 is formed by forming.

By performing the above-described resist coating process, a resist film 16 is formed on the surface of the thin film 14 of the thin film-attached substrate 15 shown in Fig. 4A, and the resist film 16 is formed as shown in Fig. 4B. The mask blank 10 can be manufactured. A predetermined pattern is drawn and developed on the resist film 16 of the mask blank 10 to form a resist pattern. Using this resist pattern as a mask, the thin film 14 (for example, a light-shielding film) is dry etched to form a mask pattern. (13) (FIG. 4C) can be formed to fabricate the transfer mask 18.

As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this. For example, depending on the manufacturing method of the mask blank 10, the mask blank 10 may be manufactured by directly forming the resist film 16 on the main surface of the square-shaped substrate 11. Even in that case, in order to directly form the resist film 16 on the main surface of the square-shaped substrate 11, the manufacturing method of the present invention including the above-described resist coating step can be preferably used.

<Example>

Next, the manufacturing method of the mask blank 10 and the manufacturing method of the transfer mask 18 are demonstrated concretely based on an Example.

(Example 1)

On a synthetic quartz glass substrate having a size of 152.4 mm x 152.4 mm, a light shielding film 2 made of a MoSiN film (light shielding layer) and a MoSiN film (surface anti-reflection layer) and an etching mask film 3 were sequentially formed by sputtering. It formed and obtained the substrate 15 with a thin film. The formation of the light shielding film 2 and the etching mask film 3 was specifically performed as follows. In addition, the same thin film 14 was formed in the mask blank 10 of Examples 2 to 4 and Comparative Example 1.

On the translucent substrate 11 made of synthetic quartz glass, a single-piece sputtering device is used, and a mixed target of molybdenum (Mo) and silicon (Si) (atomic% ratio Mo:Si=13:87) is used as a sputtering target. Then, in a mixed gas atmosphere of argon and nitrogen, a MoSiN film (lower layer (light shielding layer)) is formed to have a thickness of 47 nm by reactive sputtering (DC sputtering), and then a Mo/Si target (atomic% ratio Mo:Si= 13:87), in a mixed gas atmosphere of argon and nitrogen, a MoSiN film (upper layer (surface anti-reflection layer)) was formed to have a thickness of 13 nm to form a lower layer (film composition ratio Mo: 9.9 atomic%, Si: 66.1 atomic%) , N: 24.0 atomic %) and the upper layer (film composition ratio Mo: 7.5 atomic %, Si: 50.5 atomic %, N: 42.0 atomic %) for ArF excimer laser (wavelength 193 nm) light shielding film 2 (total film thickness 60nm) was formed. In addition, the elemental analysis of each layer of the light-shielding film 2 used the Rutherford backscattering analysis method.

Next, the light shielding film 2 was provided and the substrate 15 with a thin film was subjected to a heat treatment (annealing treatment) at 450 DEG C for 30 minutes to reduce the film stress of the light shielding film 2.

Subsequently, an etching mask film 3 was formed on the upper surface of the light shielding film 2. Specifically, in a single-sheet sputtering apparatus, a CrN film (film composition ratio Cr: 75.3 atomic%, N: 24.7) by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon and nitrogen using a chromium (Cr) target. Atomic%) was formed into a film with a thickness of 5 nm. Further, by annealing the etching mask film 3 (CrN film) at a temperature lower than that of the annealing treatment of the light shielding film 2, the stress of the etching mask film 3 is as low as possible without affecting the film stress of the light shielding film 2 It was adjusted so that (preferably, the film stress was substantially zero). By the above procedure, the substrate 15 with a thin film of Example 1 was obtained.

Subsequently, the resist liquid 26 was rotated onto the thin film-attached substrate 15 by a resist coating process to form a resist film 16 on the surface of the thin film 14. As the resist and solvent contained in the resist liquid 26, the following ones were used.

Resist: Positive chemical amplification resist WHT-015 1700Å (manufactured by Fujifilm Electronics Materials)

Solvent: Mixed solvent of PGMEA and PGME

Table 1 shows the rotational speed and time of the thin film-attached substrate 15 in each step during the resist coating step of Example 1. The "start time" and "end time" in Table 1 are shown as 0 seconds when the dropping of the resist liquid 26 is started in the dropping step (S2). In addition, "continuation time" represents the time from the start time to the end time of each process. In addition, the start time and start time of dripping of the resist liquid 26 correspond to the time t _A and the time t _B in FIG. 1, respectively. The start time of dropping before the rotation process (S1) ( "S1a. Accelerating step") corresponds to the time t _X of Figure 1; The start time and end time of "S2. dropping process" correspond to the time t _Y and the time t _Z in FIG. 1. In addition, in all Examples and Comparative Examples, the resist liquid 26 was dripped over the entire dropping step (S2). Therefore, the start time and end time of the dropping step (S2) are time t _A (= time t _Y ) and time t _B (= time t _Z ). The same applies to Tables 2 to 5.

In addition, Table 1 does not describe the change from the rotation speed of the substrate of 1000 rpm in the rotational speed maintaining step (S3) after dropping to the rotational speed of the substrate in the drying degree adjustment step (S4) of 500 rpm. Since the change time of the rotational speed was a short time of about 0.05 seconds, the description was omitted. The same applies to the change in the rotation speed from the drying degree adjustment step (S4) to the homogenization step (S5) and the change in the rotation speed from the homogenization step (S5) to the drying step (S6). In addition, the same is true for Examples 2 to 4 and Comparative Example 1.

Further, in the homogenizing step (S5) and the drying step (S6), while the thin film-attached substrate 15 is rotating, forced exhaust is always continuously performed, and the thin-film-attached substrate ( The air flow 34 was generated so that the air flow 34 flows from the center of 15) in the outer circumferential direction. Therefore, the thin film-attached substrate 15 effectively collects the liquid of the resist liquid 26 generated on the outer circumferential portion (the main surface end of the substrate 11) of the thin-film-attached substrate 15 by rotation of the thin-film-attached substrate 15. It could be scattered outside In addition, it was possible to effectively suppress the liquid accumulation of the resist liquid 26 generated in the four corners of the thin-film-attached substrate 15 or the outer circumferential portion of the thin-film-attached substrate 15 from returning to the central portion of the thin-film-attached substrate 15. As a result, it is possible to reduce the thick film regions of the resist film 16 formed at the four corners and the periphery of the thin film-attached substrate 15, or to reduce the swelling of the film thickness in the region (to suppress thickening). there was.

Subsequently, the substrate 15 with the thin film on which the resist film 16 was formed was transferred to a heat drying device and a cooling device, and a predetermined heat drying treatment was performed to dry the resist film 16 to prepare a mask blank 10.

(Example 2)

The mask blank 10 of Example 2 was produced in the same manner as in Example 1, except that the step before dropping was not performed during the resist coating step and the rotation speed in the homogenizing step (S5) was 1400 rpm. Table 2 shows the rotation speed and time of the thin film-attached substrate 15 in each step during the resist coating step of Example 2.

(Example 3)

The mask blank 10 of Example 3 was produced in the same manner as in Example 1, except that the rotational speed in the homogenization step (S5) during the resist coating step was set to 1600 rpm. Table 3 shows the rotational speed and time of the thin film-attached substrate 15 in each step during the resist coating step of Example 3.

(Example 4)

In Example 4, in the rotation step before dropping during the resist coating step, the acceleration in the acceleration step (S1a) was set at 250 rpm/sec for 2 seconds, the constant speed step (S1b) was not performed, and the resist liquid ( 26) was dripped. In addition, in Example 4, the drying degree adjustment process (S4) was not performed, and the homogenization process (S5) was performed immediately after completion|finish of the rotational speed maintenance process (S3) after dripping. Table 4 shows the rotational speed and time of the thin film-attached substrate 15 in each step during the resist coating step of Example 4.

(Example 5)

In this embodiment, the rotation speed of the pre-dropping step (S1b) is set to 300 rpm, the rotational speed maintenance step (S3) after dropping from the rotation speed of the dropping step (S2) is set to 400 rpm for 4.5 seconds, and the drying degree adjustment step (S4) is set to 200 rpm. For 8 seconds, the mask blank 10 of Example 5 was produced in the same manner as in Example 1, except that the rotation speed in the homogenization step (S5) during the resist coating step was set to 1600 rpm. Table 5 shows the rotational speed and time of the thin film-attached substrate 15 in each step during the resist coating step of Example 5.

(Example 6)

In this embodiment, the rotation speed in the pre-dropping step (S1b), the dropping step (S2), and the post-dropping rotation speed maintenance step (S3) is set to 1800 rpm, the drying degree adjustment step (S4) is set to 1000 rpm, and the resist coating step The mask blank 10 of Example 6 was produced in the same manner as in Example 1, except that the rotational speed in the homogenization step (S5) in the middle was set to 1600 rpm. Table 5 shows the rotational speed and time of the thin film-attached substrate 15 in each step during the resist coating step of Example 6.

(Comparative Example 1)

In Comparative Example 1, the rotation step before dropping was not performed, and in the dropping step (S2), the resist was dropped while the rotation of the thin film-attached substrate 15 was stopped. Thereafter, in Comparative Example 1, it was maintained at 0 rpm as the rotational speed maintaining step (S3) after dripping, and the drying degree adjustment step (S4) at a rotational speed of 300 rpm, and a homogenization step (S5) at a rotational speed of 1700 rpm were performed. The drying step (S6) of Comparative Example 1 is the same as that of Example 1. Table 5 shows the rotational speed of the thin film-attached substrate 15 in each step during the resist coating step of Comparative Example 1.

<Evaluation>

The film thickness uniformity, sensitivity, and number of defects of the mask blanks 10 of Examples 1 to 4 and Comparative Example 1 prepared as described above were measured.

(1) film thickness measurement

The film thickness of the resist film 16 of the mask blank 10 of Examples 1 to 4 and Comparative Example 1 was measured as follows. As a film thickness measuring device, a High speed mapping elipsometer ME-210 (manufactured by Photonic Latis) was used. In the measurement of the film thickness, 1,369 points were measured from the coordinates (-72mm, -72mm) to the coordinates (72mm, 72mm) with the center coordinates of the thin film-attached substrate 15 as (0mm, 0mm) at 4mm intervals. From these measurement results, a value obtained by subtracting the minimum value from the maximum value of the film thickness as the uniformity of the film thickness was obtained. In addition, 3σ (σ: standard deviation) of the measured value was obtained as a deviation in the film thickness. Table 6 shows the uniformity of the film thickness obtained as described above and 3σ of the measured value of the film thickness.

(2) Sensitivity measurement

Using the mask blank 10 of Examples 1 to 4 and Comparative Example 1, an L/S pattern in which the design dimension of the width of the L/S space portion was 130 nm was produced (drawn) under the following apparatus and conditions. In addition, the line width remaining after drawing was 80 nm.

ㆍ Drawing device: Nippon Denshi JBX-3030, Dose=22, η=0.5

-PEB (heat treatment after exposure): Heat treatment was performed at 110°C for 10 minutes.

ㆍDeveloper: CLEAN TRACK ACT (registered trademark) M (made by Tokyo Electron Co., Ltd.)

ㆍDeveloper: TMAH (tetramethylammonium hydride) 2.38% solution

ㆍEvaluation device: CD-SEM (critical dimension SEM) LWM9045 (manufactured by Aventist)

ㆍEvaluation method: CDU (Critical Dimension Uniformity) was measured. Specifically, the 3σ deviation (unit: nm) of the actual dimension on the mask of the shape portion that has the same tone and the same dimension as important on the mask was measured.

From the result of the sensitivity measurement, the pass or not was judged as follows. Table 6 shows the results of determining the pass or not of the sensitivity obtained as described above.

ㆍDetermining whether or not to pass:

◎: 3σ<1.5nm (Can achieve 1.5nm of target value in 2014)

○: 1.5nm≤3σ<2.0nm (Achieve 1.9nm of target value in 2013)

△: 2.0nm≤3σ<2.5nm

×: 2.5nm≤3σ

(3) defect evaluation

The mask blank 10 of Examples 1 to 4 and Comparative Example 1 was inspected for defects. Specifically, the surface of the manufactured mask blank 10 was inspected for defects using a defect inspection apparatus (M6640 manufactured by LaserTek) with a sensitivity of 60 nm using a laser interference confocal optical system. Based on the result of the defect inspection, it was judged whether or not the defect evaluation was passed as follows. Table 6 shows the results of the defect evaluation pass or not.

ㆍJudge whether or not to pass

A size of 0.2 mu or more was determined as a clear foreign matter, and was set as the following index.

◎: No foreign matter over 0.2㎛

○: The maximum defect is 0.2 μm or more and less than 0.3 μm, and the defect that falls within the range is 2 or less.

△: The maximum defect is less than 0.5 μm, and the size of 0.2 μm or more is 3 or less

×: 0.2 μm or more defects are 4 or more

(Consideration of results)

In Examples 1 to 6, favorable results were obtained that both the film thickness uniformity was 3.0 nm or less, and the film thickness deviation 3σ in the resist film was 1.0 nm or less. In addition, regarding the evaluation of the sensitivity uniformity of the resist films of Examples 1 to 4, the variation 3? in the resist film was good at a pattern size of 2.0 nm or less. In addition, in the defect evaluation of Examples 1 to 3 and 6, defects of 0.2 µm or more in the plane were not detected.

Examples 1 to 3 and 6 in which the spin rotation speed in the dropping step (S2) was 1000 rpm were particularly excellent in terms of defect evaluation. In the dropping step (S2), since the surface to be coated is sufficiently wetted, and high-speed rotation is performed under that situation, foreign matter adhered by the dropping of the resist liquid 26 is quickly discharged to the outside before settling in the coat layer ( I think it has become an emergency.

In Example 4, the rotational speed of 500 rpm was maintained in the dropping step (S2). In Example 4, film thickness uniformity and film thickness variation were good. However, in the defect evaluation of Example 4, defects of 0.2 µm or more were detected. This is presumed to be due to the fact that the dripping step (S2) was a relatively low rotational speed of 500 rpm, so drying was slightly advanced before film thickness uniformity was obtained, and that the progress of out-of-plane exclusion of foreign matter by centrifugal force was not sufficient. .

It is considered that the defect was detected for the same reason in Example 5 as well. In addition, in Example 5, there was a change in sensitivity of 1.5 nm or more. This is presumed to be due to the occurrence of variations in physical stimulation such as friction when the resist liquid 26 is wet and expands depending on the coating area.

In Comparative Example 1, the resist liquid 26 was dropped in a stationary state. In Comparative Example 1, since high-speed rotation was performed in the homogenization step (S5), the film thickness uniformity was not bad although it did not reach Examples 1 to 4. However, paying attention to the sensitivity uniformity, the 3? value representing the variation in pattern size evaluation was a value exceeding 2 nm. In addition, in defect evaluation, 3 or more defects having a size of 0.2 μm or more were detected. From this, it became clear that the dropping of the resist liquid 26 in a stationary state is not preferable in terms of sensitivity uniformity and defect generation.

From these results, it was found that in order to suppress the in-plane variation in resist sensitivity, a coating method in which the resist liquid 26 is dropped in an atmosphere of at least 500 rpm or higher is effective.

2: shading screen
3: etching mask film
10: mask blank
11: substrate
12: pattern line
13: mask pattern
14: thin film
15: substrate with thin film
16: resist film
18: transcription mask
20: resist liquid coating device
21: spinner chuck
22: nozzle
23: cup
24: inner ring
26: resist liquid
30: exhaust means
32: opening
34: airflow

Claims (12)

A method for manufacturing a mask blank comprising forming a resist film made of a resist material on a substrate,
The formation of the resist film,
And a dropping step for dropping a resist liquid containing a resist material and a solvent on the square-shaped substrate,
In the dropping process, when the rotation speed of the substrate at time t is R(t), the rotation speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid is 300 to 2000 rpm,
After the dropping end time t _B of the resist liquid, the rotational speed R(t) of the substrate is lower than the rotational speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid, or Including a drying degree adjustment process to stop rotation,
After the drying degree adjustment step, a method for manufacturing a mask blank comprising a homogenizing step of making the rotation speed R(t) of the substrate faster than the rotation speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid . The method for manufacturing a mask blank according to claim 1, wherein the rotation speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid is 500 to 1000 rpm. The method for manufacturing a mask blank according to claim 1 or 2, comprising a pre-dropping rotation step of rotating the substrate before starting to drop the resist liquid. delete The rotational speed R(t) (t _B <t ≤ t _B +Δt) of the substrate according to claim 1 or 2, immediately after the dropping end time t _B of the resist liquid, for a predetermined time Δt. And a post-dropping rotation speed maintenance step of maintaining the same as the rotation speed R(t _B ) of the substrate at the dropping end time t _B of the resist liquid. The method for manufacturing a mask blank according to claim 1 or 2, wherein an exhaust means for exhausting the inside of the resist liquid coating device is actuated after the dropping end time t _{B of the} resist liquid. The method for manufacturing a mask blank according to claim 1 or 2, wherein in the homogenizing step, an exhaust means for exhausting the inside of the resist liquid coating device is actuated. The method for manufacturing a mask blank according to claim 1 or 2, wherein the resist liquid is a chemically amplified resist liquid. The method according to claim 1 or 2, wherein the surface forming the resist film of the substrate is a surface of a thin film formed by a reactive sputtering method, and the thin film is made of at least Cr, Ta, Si, Mo, Ti, V, Nb and W. A method for producing a mask blank containing at least one element selected from the group consisting of. The method for manufacturing a mask blank according to claim 9, wherein the thin film contains at least Cr, and the ratio of Cr contained in the thin film is at least 50 atomic% or more. The method for manufacturing a mask blank according to claim 9, wherein the thin film contains at least Si. Forming a resist pattern by patterning the resist film of the mask blank manufactured by the method for manufacturing a mask blank according to claim 1 or 2, and forming a mask pattern using the resist pattern as a mask to prepare a transfer mask. A method of manufacturing a transfer mask, characterized in that.

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