JP2011222834A - Baking apparatus, method for forming resist pattern, method for manufacturing photo mask, and method for manufacturing mold for nanoimprint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high quality pattern with a high residual film ratio and a high contrast ratio, even if a mask substrate is composed of synthetic quartz with the thickness of 0.250 inch in forming a resist pattern with a chemically-amplified resist.SOLUTION: In a baking apparatus 50 for subjecting PAB or PEB treatment to a chemically-amplified resist, the temperatures of a second hotplate 52 and subsequent hotplates are adjusted and held at a predetermined baking temperature, and the temperature of a first hotplate 51 is adjusted and held at a higher temperature than the predetermined baking temperature so that the temperature of the surface of a mask substrate 1 can reach the predetermined baking temperature within 90 seconds.

Description

  The present invention relates to a baking processing apparatus used for production of a photomask and a nanoimprint mold used for manufacturing a semiconductor integrated circuit, a resist pattern forming method using the baking apparatus, and the resist pattern forming method. The present invention relates to a photomask manufacturing method and a nanoimprint mold manufacturing method.

Electron beam lithography is a method of drawing or exposure (hereinafter referred to as drawing) that provides a high resolution of 30 nm or less, and is used for small-scale advanced semiconductor integrated circuits that require extremely fine pattern dimensions and next-generation semiconductor integrated circuits. It has already been put to practical use in applications such as development trial manufacture, photomask manufacturing, and nanoimprint mold manufacturing.
On the other hand, despite the fact that electron beam lithography offers excellent resolution, the reason why it is not put into practical use for mass production of semiconductor integrated circuits, etc. is that the area that can be drawn at one time is compared with optical lithography (ie reduced projection exposure) Therefore, it is small, that is, it requires a long time for drawing.

  As a means for realizing the improvement in the processing speed, more specifically, as a means for increasing the sensitivity of the resist, there is a chemically amplified resist. Chemically amplified resist is already used as a microfabricated material for semiconductor manufacturing.

Whereas conventional “non” chemically amplified resists for electron beam lithography are based on a decomposition reaction or polymerization reaction by electron beam irradiation (ie, drawing), chemically amplified resists are formed in a resist film by a reaction by drawing. The reaction proceeds in a chain manner by baking after drawing using an acid as a catalyst, and high sensitivity is obtained. That is, a resist pattern can be formed with a small amount of electron beam irradiation, and high productivity can be obtained in electron beam drawing.
By the way, in a semiconductor integrated circuit manufacturing line which is mass-produced by using light exposure and a chemically amplified resist (that is, photolithography), microfabrication of a size of about 45 nm or less is already performed at the minimum. Yes. However, in order to satisfy the demands for higher performance and higher integration of semiconductor integrated circuits and the like, it is required to form a finer, more precise and higher quality resist pattern. In particular, in the production of masters for lithography used in the manufacture of semiconductor integrated circuits, such as photomasks and nanoimprint molds manufactured using electron beam lithography and chemically amplified resists, higher-quality resist patterns and There is a need for technology to form

  Here, Patent Document 1 relates to “resist polymer and chemically amplified resist composition”. After chemically applying a chemically amplified resist on a silicon wafer, post-application baking (Post Apply Bake: hereinafter, (Hereinafter referred to as “PAB”) at 120 ° C. for 60 seconds using a hot plate, followed by exposure with an ArF excimer laser exposure machine, and further post-exposure baking (hereinafter referred to as “PEB”) at 120 ° C. for 60 seconds using a hot plate. A technique for forming a resist pattern to be performed is described.

Patent Document 2 relates to “radiation-sensitive composition, compound, method for producing compound and method for forming resist pattern”, wherein a chemically amplified non-polymer type resist composition is spin-coated on a silicon wafer, and PAB A technique for forming a resist pattern by performing exposure with an electron beam drawing apparatus after processing, bake temperatures of 90 ° C., 100 ° C., and 110 ° C., fixing the bake time to 90 seconds, performing PEB processing, and then developing. Is described. Similarly, in Patent Document 2, a chemically amplified non-polymeric resist composition is spin-coated on a SiO ₂ substrate, subjected to PAB treatment at 110 ° C. for 90 seconds, and then exposed to an electron beam drawing apparatus. Describes a technique for forming a resist pattern by performing PEB processing for 90 seconds and developing processing.

  Patent Document 3 relates to “a method for evaluating the in-plane distribution of resist pattern dimensions, a method for manufacturing a photomask blank, a method for managing a photomask blank, and a resist pattern forming process”, and provides a Cr light-shielding film. A positive chemically amplified resist for EB is spin-coated on an inch square (152 x 152 mm) photomask blank, pre-baked (ie, PAB) at 120 ° C for 10 minutes with a hot plate, and a test pattern is drawn with an EB drawing machine. After that, a photomask manufacturing method is described in which a pre-development bake (that is, PEB) is performed at 120 ° C. for 10 minutes on a hot plate, a development process is performed, and a resist pattern is formed by rinsing and spin drying. .

  Further, Patent Document 4 relates to “resist pattern dimension control method and baking processing apparatus”, a positive chemically amplified resist is applied on a 6-inch Cr mask, and a pattern is drawn using an electron beam drawing apparatus. Then, a photomask manufacturing method is described in which PEB processing is performed at 90 ° C. for 600 seconds (routine conditions).

JP 2003-140346 A JP 2009-173625 A JP 2005-326581 A Japanese Patent Laid-Open No. 11-72927

Hideo Kobayashi, Proceedings of SPIE Vol. 5853-17

  Development and prototyping of the chemically amplified resist (composition) mentioned here is, for example, as described in Patent Document 1 or Patent Document 2, a silicon wafer (outer dimensions, thickness, etc.) made in a semiconductor industry standard shape ( For example, a 6-inch silicon wafer (150 mm diameter, thickness 0.675 mm) is used. Alternatively, a substrate on which an aluminum film or the like is formed on the silicon wafer surface is used. Then, a chemically amplified resist solution is spin-coated on a silicon wafer (hereinafter also referred to as a wafer), and then the wafer on which the chemically amplified resist film is formed is placed on a hot plate adjusted and held at a predetermined temperature for 90 seconds. The wafer is stood still and baked, and then the wafer is continuously transferred onto a cooling plate set and held at room temperature, for example, and allowed to cool sufficiently to complete the PAB process. Next, drawing is performed by an electron beam drawing apparatus. Subsequently, the wafer subjected to the drawing was baked by allowing it to stand for 90 seconds on a hot plate adjusted and held at a predetermined temperature in the same manner as the PAB process described above, and then continuously adjusted and held at room temperature, for example. The wafer is transferred to the cooling plate, allowed to stand and sufficiently cooled, and the PEB process is completed. Thereafter, the resist film is developed with a predetermined developer to form a chemically amplified resist pattern.

By the way, determination of the baking conditions for obtaining the best resist pattern shape of a certain chemically amplified resist is performed by the following means.
The resist pattern forming process (hereinafter referred to as resist pattern forming process) of the chemically amplified resist represented by the above, and the baking temperature in PAB and PEB is changed to several levels in the resist pattern forming process. After pattern formation, the obtained resist pattern is observed with a scanning electron microscope or the like to determine the baking conditions for obtaining the best resist pattern shape, that is, the combination of PAB temperature and PEB temperature.

  Here, as described in, for example, Patent Document 1 or 2, the processing time of PAB and PEB in the resist pattern forming process is 90 seconds (or 60 seconds) in both baking processes when the wafer is a substrate. And the same fixed processing time is used.

  By the way, the photomask for the most advanced optical lithography has a size of 6 inches square and a thickness of 0, which is made into a semiconductor industry standard shape (outer dimensions, plate thickness, etc.) from the required pattern area and shape stability. A substrate made of 250-inch synthetic quartz (hereinafter also referred to as a mask substrate) is used. Moreover, the nanoimprint mold may be manufactured by diverting the mask substrate to a processing apparatus and process for manufacturing a photomask for the purpose of reducing the manufacturing cost. In that case, a desired mold pattern is formed on the mask substrate. Then, after the mold pattern formation is completed, the nanoimprint mold is completed by cutting into a desired predetermined shape as necessary.

Here, the apparatus for baking the mask substrate has substantially the same configuration as the wafer baking apparatus, and a hot plate set and held at a predetermined temperature is used.
When the wafer is a substrate, the time required for the substrate surface (that is, the resist film) to reach a desired baking temperature of about 80 to 160 ° C. is about 5 to 20 seconds (see FIG. 6A). ). On the other hand, in the case of the mask substrate, for the substrate surface (that is, the resist film) to reach the desired baking temperature of about 80 to 160 ° C. as described above, depending on the configuration of the baking processing apparatus, for example, 500 seconds. The above is required (see FIG. 6B). This is due to a difference in thermal conductivity and plate thickness between the wafer and the mask substrate.
In the case of the mask substrate, even if the substrate surface (that is, the resist film) reaches a predetermined baking temperature, in consideration of safety for ensuring in-plane uniformity of the substrate surface temperature, for example, Patent Document 3 Alternatively, as described in Patent Document 4, a baking process for 10 minutes (600 seconds) is performed.

  By the way, even when a chemically amplified resist is developed and prototyped for use in the production of a photomask made of the mask substrate or in the production of a mold for nanoimprint, the best resist pattern shape in the chemically amplified resist is obtained. In order to determine the baking conditions to be obtained, that is, to determine the combination of the PAB temperature and the PEB temperature, a silicon wafer having the shape of the semiconductor industry standard is used. The best resist pattern shape can be obtained by forming a chromium light-shielding film described in Patent Document 3 or Patent Document 4 on the surface of the silicon wafer or by directly applying a chemically amplified resist thereon. Bake conditions are determined.

This is based on the facts described below.
That is, the mask substrate is more expensive than the wafer, and is difficult to obtain except by a photomask or nanoimprint mold manufacturer.
Furthermore, other than a photomask or nanoimprint mold manufacturer (in other words, a resist manufacturer that develops and prototypes a chemically amplified resist) does not have a baking processing apparatus for PAB processing or PEB processing of the mask substrate. It depends on the reality. The main consumer of the chemically amplified resist having a high resolution of 45 nm or less is a semiconductor manufacturer or the like, not a photomask manufacturer or a mold manufacturer for nanoimprint. Therefore, in order to reduce the development cost of the resist, the resist manufacturer, even if it is a development prototype of a chemically amplified resist for producing a photomask or a mold for nanoimprinting, has the mask substrate (ie, size 6). The wafer (ie, 6-inch silicon wafer: 150 mm diameter, 0.675 mm thickness) is used as the substrate, not an inch square and 0.250 inch thick synthetic quartz substrate.

As described above, in the chemically amplified resist, the baking method for obtaining the best resist pattern shape, that is, the combination of the PAB temperature and the PEB temperature is determined by the above-described method using the wafer. . Therefore, the performance cannot be maximized unless baking is performed under the baking conditions. Depending on the composition of the chemically amplified resist or the type of the solvent constituting the solution of the chemically amplified resist, the baking time is conventionally 60 seconds or 90 seconds.
On the other hand, even on the mask substrate, the conventional bake processing apparatus, where the surface of the mask substrate should reach the predetermined baking temperature within 90 seconds or 60 seconds, depends on the apparatus configuration. As an example, it takes 500 seconds or more (see FIG. 6B). As a result, the accumulated heat received by the resist film is significantly excessively baked, and depending on the resist type, the remaining film ratio of the undrawn portion is greatly degraded, and the pattern contrast (γ value) is also greatly degraded. As a result, the resist pattern quality is greatly degraded.

  On the other hand, when developing and prototyping a chemically amplified resist for use in manufacturing a photomask or nanoimprint mold, this is a typical baking time when the wafer is used as a substrate while the wafer is used as a substrate. Instead of the second or 90 second baking time, a baking time corresponding to an arbitrary time (for example, 600 seconds) in which the surface of the mask substrate can reach a predetermined temperature (80 to 160 ° C.) is adopted. It is also conceivable to determine a baking condition for obtaining the best resist pattern shape, that is, a method for determining a combination of PAB temperature and PEB temperature.

The present inventor actually tried the method (see Non-Patent Document 1).
Specifically, the mask uses a positive chemically amplified resist in which the remaining film ratio of the undrawn portion after development processing (hereinafter also referred to as the remaining film ratio) changes linearly and steeply with respect to the baking time. The wafer baking time corresponding to baking the substrate for 600 seconds was determined to be 443 seconds.
While the wafer is used as a substrate, the mask substrate can be processed for a baking time equivalent to 600 seconds baking (that is, 443 seconds) instead of 90 seconds ((a) condition) (See FIG. 8A). As a comparative example, the result when the mask substrate 1 is baked for 600 seconds is shown (refer to (b) condition, FIG. 8B). However, the chemically amplified resist developed and prototyped using the wafer and the 90-second baking process, which is a standard baking time for the wafer, maximizes the performance under the conditions (a) and (b). It could not be expressed. Specifically, the remaining film rate and the drawing amount (electron beam irradiation) obtained under the condition that the PAB and PEB treatments are each 90 seconds using the wafer as a substrate (refer to (c) condition, see FIG. 8C). The remaining film sensitivity curve obtained under the above conditions (a) and (b) shows a decrease in the remaining film rate of the undrawn portion, as compared with the relationship with the amount (hereinafter also referred to as the remaining film sensitivity curve). In addition, the pattern contrast (γ value) deteriorated (see FIG. 8).

  Again, in the case of the mask substrate and the case where the wafer is a substrate, the substrate surface temperature rise rate when the substrate is left on a hot plate, or alternatively after the baking process, For example, there is a great difference in the rate of decrease in the substrate surface temperature when it is transferred to a cooling plate set and maintained at room temperature and allowed to stand (see FIG. 6). Under this influence, a chemically amplified resist developed and prototyped using the wafer as a substrate and a baking time of PAB and PEB of 90 seconds, and its best pattern shape (that is, the remaining film of the undrawn portion) The rate and contrast (γ value) cannot be reproduced or achieved with the mask substrate.

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and has a size of 6 inches square and a thickness of 0.250 inches for manufacturing a photomask or a nanoimprint mold. Even in the case of a substrate made of synthetic quartz (mask substrate), in a chemically amplified resist, after a predetermined development process, a high residual film ratio can be maintained for an undrawn portion, and a high pattern contrast is obtained. An object of the present invention is to provide a baking processing apparatus capable of providing a high-quality resist pattern. Another object of the present invention is to provide a resist pattern forming method using the baking processing apparatus, a photomask manufacturing method using the resist pattern forming method, and a nanoimprint mold manufacturing method.

The present inventor uses a chemically amplified resist from the viewpoint of resist sensitivity (ie, drawing productivity) when drawing or exposing with electron beam or laser light (hereinafter referred to as drawing), and the mask substrate. Even so, various means for forming and providing a higher-quality resist pattern were studied.
In the examination, the present inventor made a processing time for post-application baking (PAB) and post-exposure baking (PEB) of the chemically amplified resist, and a baking process when the mask substrate and the wafer are used as substrates. It has been found that the difference in time, or the temperature rising rate at the start of baking the substrate surface of the mask substrate and the wafer and the temperature decreasing rate at the start of cooling greatly affect the quality of the resist pattern.

Conventionally, PAB and PEB conditions for chemically amplified resists are roughly divided into a baking temperature and a baking time.
Regarding the baking temperature, the optimum temperature (predetermined baking temperature) is determined depending on the material and composition of the chemically amplified resist and the solvent constituting the solution.
On the other hand, the baking time is determined in consideration of productivity and the like, and as shown in Patent Document 1 and Patent Document 2, in PAB and PEB, the material and composition of chemically amplified resist and the solution thereof are used. Although it depends on the solvent to be formed, it is conventional or current to be fixed at 60 seconds or 90 seconds. In the case of the wafer, even if the baking time is 60 seconds or 90 seconds, the substrate surface temperature (that is, the resist film formed on the wafer) is a predetermined baking temperature of about 80 to 160 ° C. It depends on the reason that you can reach it enough.
In addition, as described above, even in the case of a chemically amplified resist intended for the production of a photomask using the mask substrate or a mold for nanoimprint, the wafer is used for the substrate in the development prototype, and the baking is performed. As described above, the processing time is 90 seconds or 60 seconds.
However, in the case of the mask substrate, the time required for the substrate surface, that is, the resist film to reach a baking temperature of about 80 to 160 ° C. in the first place greatly exceeds 90 seconds, depending on the configuration of the baking processing apparatus. , Approximately 600 seconds or more. With a baking time of 60 seconds, the surface temperature of the mask substrate cannot reach 80 ° C.

On the other hand, the present inventor, even with the mask substrate, has a baking process time of 90 seconds that was used in the development and trial production of the chemically amplified resist with the substrate surface at the predetermined baking temperature, that is, the resist film. Or, we have intensively studied how to get within that.
As a result, the present inventor has arranged a plurality of hot plates used in the baking process in succession, and adjusted and maintained the second hot plate at a predetermined baking temperature of the chemically amplified resist to be baked. And
On the other hand, the first hot plate that starts baking the mask substrate is adjusted and held at a temperature higher than the baking temperature,
The rate of temperature rise on the surface of the mask substrate immediately after the start of the baking process is calculated by dividing the predetermined baking process temperature for the chemically amplified resist to be baked by the baking process time during the resist design development. Adjust and hold the temperature so that it becomes larger, and configure as a bake treatment device,
The time for which the mask substrate is allowed to stand on the first hot plate (hereinafter also referred to as the stand time) is the maximum temperature that the surface of the mask substrate reaches during the PAB or PEB process and the stand time. By determining and determining the relationship with
Even with the mask substrate, it has been found that the substrate surface, that is, the resist film reaches the predetermined baking temperature (80 to 160 ° C.) within 90 seconds without overshooting.

In the first aspect of the present invention, a substrate for producing a photomask or a mold for nanoimprinting (hereinafter also referred to as a mask substrate)
A baking apparatus for applying a chemically amplified resist (hereinafter also referred to as a resist) and then performing post-application baking (post apply bake: hereinafter referred to as PAB).
And / or a resist film is formed by applying the resist, subjected to PAB treatment, and a post-exposure bake treatment of the mask substrate having the resist film on which a desired pattern is drawn (hereinafter referred to as PEB). Bake device for performing
It is characterized by comprising a plurality of and continuously arranged hot plates and a single or plural cooling plates.
A second aspect of the present invention is the baking processing apparatus according to the first aspect, wherein the mask substrate is first transferred and allowed to stand out of the plurality of continuously arranged hot plates. The first hot plate for starting the baking process is set to a temperature higher than a predetermined baking temperature of the resist to be baked. Following the baking process on the first hot plate, the mask substrate is set. The second plate or the second and subsequent hot plates that perform the resist baking process after being transferred and allowed to stand are set to a predetermined baking temperature of the resist to be baked. To do.
A third aspect of the present invention is the baking processing apparatus according to the first or second aspect,
First, the temperature rise rate (hereinafter also referred to as “Ramp”) of the surface of the mask substrate after the start of baking by the first hot plate that transfers the mask substrate and leaves it stationary to start the baking processing is the baking processing. Larger than a value obtained by dividing a predetermined baking processing temperature (hereinafter also referred to as Temp) for a chemically amplified resist by a baking processing time (hereinafter also referred to as Time) at the time of resist design development, that is, (Ramp)> ((Temp) / (Time)).
A fourth aspect of the present invention is the baking apparatus according to any one of the first to third aspects, wherein the mask substrate is transferred to a first hot plate and allowed to stand for baking. Until the mask substrate leaves the hot plate that is used at the end of the second or third hot plate or after the second hot plate or the third hot plate. The time (hereinafter also referred to as “BakeTime”) does not exceed the baking process time (hereinafter also referred to as “Time Origin”) at the time of resist design development, that is, (BakeTime) ≦ (Time Origin).
A fifth aspect of the present invention is the baking processing apparatus according to any one of the first to fourth aspects, wherein the mask substrate is transferred to a first hot plate and then allowed to stand ( Hereinafter, the standing time 1) is characterized in that the relationship between the standing time 1 and the maximum temperature that the surface of the mask substrate reaches during the PAB or PEB treatment is determined in advance.
A sixth aspect of the present invention is the baking apparatus according to any one of the first to fifth aspects,
Following the plurality of consecutively arranged hot plates, at least one of the one or more cooling plates is set and maintained at a temperature that does not cause condensation near the dew point.
A seventh aspect of the present invention is a substrate for producing a photomask or a nanoimprint mold, which is a substrate made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches (hereinafter also referred to as a mask substrate). ,
A resist pattern forming method in which a chemically amplified resist (hereinafter also referred to as a resist) is applied, and then a post-application baking process (hereinafter referred to as PAB) is performed.
And / or a resist film is formed by applying the resist, subjected to PAB treatment, and a post-exposure bake treatment of the mask substrate having the resist film on which a desired pattern is drawn (hereinafter referred to as PEB). A resist pattern forming method for performing
The processing of the mask substrate includes a step of continuously using at least two or more of the hot plates arranged in succession, transferring the mask substrate to the first hot plate, and allowing the mask substrate to stand. A process of transferring the mask substrate, which has been transferred and placed on a second hot plate, to a second hot plate, or a second hot plate, and performing a baking process, and the baking process. And a step of transferring the mask substrate to a single or a plurality of cooling plates, allowing the mask substrate to stand, and cooling.
An eighth aspect of the present invention is the resist pattern forming method according to the seventh aspect, wherein the mask substrate is first transferred and allowed to stand out of the plurality of continuously arranged hot plates. The first hot plate for starting the baking process is set to a temperature higher than a predetermined baking temperature of the resist to be baked, and after the baking process on the first hot plate, the mask The second plate or the second and subsequent hot plates that transfer the substrate and stand still to continue the resist baking process should be set to a predetermined baking temperature for the resist to be baked. Features.
A ninth aspect of the present invention is the resist pattern forming method according to the seventh or eighth aspect,
First, the temperature rise rate (hereinafter also referred to as “Ramp”) of the surface of the mask substrate after the start of baking by the first hot plate that transfers the mask substrate and leaves it stationary to start the baking processing is the baking processing. Greater than a value obtained by dividing a predetermined baking temperature (hereinafter also referred to as Temp) for the chemically amplified resist by the baking time (hereinafter also referred to as Time) at the time of resist design development,
That is, (Ramp)> ((Temp) / (Time)).
A tenth aspect of the present invention is the resist pattern forming method according to any one of the seventh to ninth aspects,
After the mask substrate is transferred to the first hot plate and allowed to stand and the baking process is started, and after leaving the plurality of final hot plates, that is, after the second or third hot plate. Until the mask substrate leaves the hot plate used at the end of the baking process, this baking process time (hereinafter referred to as “BakeTime”) does not exceed the baking process time during resist design development (hereinafter also referred to as “Time Origin”). That is, (BakeTime) ≦ (Time Origin).
An eleventh aspect of the present invention is the resist pattern forming method according to any one of the seventh to tenth aspects, wherein the mask substrate is transferred to a first hot plate and then allowed to stand still. (Hereinafter also referred to as standing time 1) is characterized in that a relationship between the standing time 1 and the maximum temperature that the surface of the mask substrate reaches during the PAB or PEB treatment is determined in advance.
A twelfth aspect of the present invention is the resist pattern forming method according to any one of the seventh to eleventh aspects, wherein one or a plurality of cooling plates are provided following the plurality of continuously arranged hot plates. At least the first of these is set and maintained at a temperature at which dew condensation does not occur near the dew point.
In a thirteenth aspect of the present invention, a chemically amplified resist (hereinafter also referred to as a resist) is applied to a substrate made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches (hereinafter also referred to as a mask substrate). Then, a photomask manufacturing method for performing post-application baking (Post Apply Bake: hereinafter referred to as PAB) and / or applying the resist to form a resist film, and performing PAB processing A method of manufacturing a photomask for performing post-exposure baking (hereinafter referred to as PEB) of the mask substrate having the resist film on which a desired pattern is drawn, wherein the mask substrate includes a plurality of processes. In addition, the mask substrate is used as the first hot plate by continuously using at least two of the hot plates arranged continuously. Transferring to a plate and allowing to stand;
The mask substrate transferred to the first hot plate and allowed to stand is transferred to the second hot plate or the second and subsequent hot plates and left to perform baking, and the baking is continued. And the step of transferring the mask substrate to a single or a plurality of cooling plates, allowing the mask substrate to stand, and cooling.
In a fourteenth aspect of the present invention, a chemically amplified resist (hereinafter also referred to as a resist) is applied to a substrate made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches (hereinafter also referred to as a mask substrate). Then, a nanoimprint mold manufacturing method for performing post-application baking (Post Apply Bake: hereinafter referred to as PAB), and / or applying the resist to form a resist film, and performing PAB processing A method of manufacturing a nanoimprint mold for performing post-exposure baking (hereinafter referred to as PEB) of the mask substrate having the resist film on which a desired pattern has been applied. Using at least two or more of the hot plates arranged in succession, The step of transferring the mask substrate to the first hot plate and allowing it to stand still, and the step of transferring the mask substrate transferred to the first hot plate to the second hot plate, or the second hot plate or subsequent hot plates, are carried out. And a step of performing a baking process by placing and standing, and a process of transferring the mask substrate to a cooling plate or a plurality of cooling plates and allowing to cool by standing after the baking process. And

  According to the baking processing apparatus of the present invention, even if the mask substrate is made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches, the chemically amplified resist film applied to the mask substrate is treated with the chemical substrate. It becomes possible to perform the processing within a predetermined baking temperature within the baking processing time at the time of designing and developing the amplification resist. As a result, it is possible to avoid excessively baking the chemically amplified resist film, maintain a high residual film ratio for the undrawn portion, and ensure a high pattern contrast, thereby forming a high-quality resist pattern. Can be provided. In addition, a high-quality photomask and nanoimprint mold can be produced and provided using the high-quality resist pattern.

It is a cross-sectional schematic diagram for demonstrating the manufacturing process of the mold for nanoimprint which concerns on this embodiment. It is a section schematic diagram of the bake processing device concerning this embodiment. Transition of temperature reached on the surface of the mask substrate according to the present invention (surface temperature of the mask substrate) and time for which the mask substrate is transferred to the first hot plate and allowed to stand (elapsed time after the start of baking) It is an example which shows the relationship with time. According to the present invention, after the mask substrate is transferred to the first hot plate, the time that the mask substrate should be allowed to stand (the standing time) and the temperature that the surface of the mask substrate should reach (on a certain chemically amplified resist) It is an example which shows the relationship with a suitable predetermined baking temperature. It is an example of the comparison with the residual film sensitivity curve of a certain chemically amplified resist by the baking processing apparatus and resist pattern formation method which concerns on this invention, and the residual film sensitivity curve of a certain chemically amplified resist by the conventional method. It is the schematic of the relationship between the substrate surface temperature in the baking process of the said wafer and the said mask board | substrate, and baking process time (transition during the baking process of a substrate surface temperature). It is the schematic which shows transition of a mask substrate surface temperature, and temperature rising rate when a hot plate is adjusted and hold | maintained at 225 degreeC and a mask substrate is moved and left still. A case where the distance between the mask substrate and the upper surface of the hot plate is 100 μm is shown as (a) and a case where the distance is 60 μm. This is a residual film sensitivity curve (relationship between the residual film ratio and the electron beam exposure amount) of a chemically amplified resist, and when a baking process corresponding to a case where a mask substrate is baked for 600 seconds using a wafer as a substrate (a ), And (b) when the mask substrate is baked for 600 seconds, and (c) when the wafer is baked for 90 seconds with the wafer as the substrate (c).

<Embodiment 1>
Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 which is a schematic cross-sectional view for explaining a manufacturing process of a nanoimprint mold and FIG. 2 which is a schematic cross-sectional view of a baking processing apparatus of the present invention.

(Configuration of baking processing equipment)
First, a hot plate 51 and 52 and a cooling plate 53 are sequentially arranged in sequence, and a mask substrate 1 (hereinafter also referred to as mask substrate 1) made of synthetic quartz having a size of 6 inches square and a plate thickness of 0.250 inches. Bake provided with a substrate transfer mechanism 54 for transferring the hot plates 51 and 52 and the cooling plate 53 in this order and allowing them to stand at different predetermined standing times to advance the baking process of the mask substrate 1. A processing device 50 is prepared.

Here, the hot plates 51 and 52 are composed of, for example, two aluminum plates of 250 mm square and 25 mm thick. Then, a mica heater designed so that the upper surface (surface) temperature of the hot plates 51 and 52 on which the mask substrate 1 is placed is uniform within the surface of the upper surface (250 mm square, particularly the center 6 inch square). There is a heating mechanism sandwiched between the two aluminum plates, and a temperature measuring element such as a platinum resistance temperature measuring element connected to a temperature controller is arranged near the center and near the surface of the 25 mm aluminum plate on the upper surface side. (The heating mechanism, temperature controller, and temperature sensor are not shown). Further, the temperature controller adjusts and holds the hot plates 51 and 52 at predetermined temperatures by adjusting the ON / OFF of the mica heater or the output continuously and stepwise. The mica heater has a capacity of 700 W. When the mask substrate 1 is placed on the upper surface of the hot plate 51 or 52, the heater power or the temperature at which the temperature of the hot plate 51 or 52 does not decrease from the predetermined temperature. Any heater capacity may be used.
Next, for example, the cooling plate 53 is formed by hollowing out a 250 mm square and 50 mm thick aluminum plate, filling the hollow with a coolant adjusted to a predetermined temperature by a constant temperature water supply device, and supplying the constant temperature water What is necessary is just a heat exchange mechanism circulated between apparatuses (a heat exchange mechanism and a constant temperature water supply apparatus are not shown in figure). Further, in order to cool the baked mask substrate 1 as quickly as possible, the cooling plate 53 and the refrigerant are adjusted and held at a temperature as close as possible to the dew point in a range where condensation does not occur. Specifically, as an example, the ambient temperature was 22.5 ° C. and the relative humidity was 40%.

  Further, when the mask substrate 1 is placed on the upper surfaces of the hot plates 51 and 52 and the cooling plate 53, for example, a heat-resistant resin having a thickness of 100 μm is used so that the back surface of the mask substrate 1 and the upper surface are not in direct contact. A plurality of tapes 55 (for example, three locations) were sandwiched between them to serve as spacers (also referred to as Proximity Gap). This is to prevent the back surface of the mask substrate 1 from being scratched, and to alleviate that the non-uniformity of the temperature of the upper surface and the surface of the hot plates 51 and 52 and the cooling plate 53 is directly reflected on the mask substrate 1. To play a role. In place of the spacer made of the heat resistant resin, a sapphire sphere or a pin having a sapphire sphere disposed at the tip may be used as the spacer. What is necessary is just to arrange | position so that the parallelism with the back surface of the mask substrate 1, and the hot plates 51 and 52 and the cooling plate 53, and each upper surface may be maintained.

Here, the bake processing apparatus is configured by continuously arranging two hot plates and one cooling plate, but it may be configured by three or more hot plates. Two or more units may be used. In the baking apparatus, two hot plates and one cooling plate are continuously arranged. However, they may be arranged obliquely, and the two hot plates may be arranged in a straight line. The cooling plate may be arranged in a direction perpendicular to the linear direction. In any case, it is sufficient that the transport mechanism 54 capable of moving the mask substrate 1 between the hot plates, between the hot plates and the cooling plates, or between the cooling plates can be configured as quickly and as short as possible.
In the present embodiment, the hot plate has a relatively simple configuration in which the mask substrate is placed on the upper surface of the hot plate via a spacer, but the upper surface of the mask substrate 1 placed on the hot plate. On the side, a heat reflecting plate or another hot plate may be arranged at a certain distance. In this embodiment, the hot plates 51 and 52 and the cooling plate 53 are fixed and the mask substrate 1 is transferred and placed by the transport mechanism 54. However, the mask substrate 1 is fixed and the hot plate 51 is fixed. The plates 51 and 52 and the cooling plate 53 may sequentially move to advance the baking process.

(Preliminary determination of the adjustment holding temperature of the first hot plate)
Next, a required temperature increase rate (Ramp) of the surface of the mask substrate immediately after the mask substrate is transferred to the first hot plate 51 and allowed to stand and baking is started is determined in advance. The adjustment holding temperature of the first hot plate 51 is determined in advance.
Here, when the predetermined baking temperature is 80 to 160 ° C. (the Temp) and the predetermined baking time is 90 seconds (the Time), the mask substrate for reaching the predetermined baking temperature within the predetermined baking time. The rate of temperature rise (Ramp) is 0.89 ° C./second (80 ° C./90 seconds) to 1.78 ° C./second (160 ° C./90 seconds). 225 ° C. was selected as the set temperature of the hot plate 51 that can execute the higher temperature increase rate (Ramp) (that is, 1.78 ° C./second). The hot plate 51 was adjusted and held at 225 ° C. in advance. The actual rate of temperature rise (Ramp) when adjusted and held at 225 ° C. is about 2 ° C./second, and the substrate surface of the mask substrate 1 is moved to a predetermined baking temperature (here) within the baking time (Time) of 90 seconds. Then, the temperature can reach 160 ° C. (Temp). Here, the distance between the mask substrate 1 and the upper surface of the hot plate 51 was 100 μm.
Further, in order to further increase the rate of temperature increase, the distance between the mask substrate and the upper surface of the hot plate 51 is further reduced, the heater capacity of the hot plate 51 is further increased, and the mask substrate 1 is placed on the hot plate 51. At this time, a heat reflecting plate or another hot plate may be provided on the upper surface. Here, FIG. 7A shows the temperature increase rate of the surface of the mask substrate 1 when the hot plate 51 is adjusted and held at 225 ° C. and baking is started. In FIG. 7B, as a reference example, the hot plate 51 is similarly adjusted and held at 225 ° C., but the surface of the mask substrate 1 when the distance between the mask substrate 1 and the upper surface of the hot plate 51 is about 60 μm. Indicates the rate of temperature rise.

(Pre-determining the time to leave the mask substrate on the hot plate)
Next, a mask substrate 2 for measuring the substrate surface temperature was prepared, in which 25 thermocouples were disposed evenly (5 × 5, interval 25 mm) in the range of the central 125 mm square of the surface of the mask substrate 1.
Then, a pseudo PAB process or PEB process is performed on the mask substrate 2 using the bake processing apparatus 50, and the surface temperature of the mask substrate 2 and the time elapsed after the start of the bake process Sought the relationship. At that time, the elapsed time from immediately after the mask substrate 2 is transferred onto the hot plate 51 and allowed to stand (hereinafter referred to as standing time 1) is changed from 10 seconds to 65 seconds to 65 seconds. It was.
Here, FIG. 3 is an example of the result of obtaining the relationship between the surface temperature of the mask substrate 2 and the lapse of time of the baking process. As an example, the results when the standing time 1 is shortened in order of (a), (b), (c) and (d) are shown.
As shown in FIG. 3, when the standing time 1 is (b), the surface temperature of the mask substrate 2 does not exceed a predetermined baking temperature (here, 130 ° C.), and the predetermined temperature is most rapidly applied. The bake temperature has been reached.
On the other hand, as the standing time 1 is shortened to (c) and (d), the surface temperature of the mask substrate 2 gradually increases as the surface temperature of the mask substrate 2 approaches the predetermined baking temperature. As a result, the time for the surface temperature of the mask substrate 2 to reach the predetermined baking temperature is delayed. On the other hand, when the standing time 1 is (a) or longer than that, the surface temperature of the mask substrate 2 overshoots exceeding the predetermined baking temperature.
From the above results, when the hot plate 51 was adjusted and held at 225 ° C. and the spacer thickness was 100 μm, the standing time 1 on the hot plate 51 was determined in advance as the condition (b).
In addition, it turns out that the surface of the mask substrate 2 reaches a predetermined baking temperature in about 80 seconds by setting the standing time 1 in FIG. 5 to the condition (b).
In addition, the surface temperature of the mask substrate 2 measured using the mask substrate 2 was obtained by obtaining an average value of the temperature display values of the 25 thermocouples as a representative value.

  Next, the predetermined baking temperature is set to 90 ° C., 110 ° C., and 150 ° C., the same relationship is obtained, and the surface temperature of the mask substrate can be reached most quickly without overshooting with respect to each of the predetermined baking temperatures. A possible standing time 1 of the mask substrate 1 on the hot plate 51 was determined. And the relationship between the said standing time 1 and predetermined baking temperature was calculated | required (refer FIG. 4). The relationship between the two is approximately approximated by a quadratic function. Therefore, the time for standing the mask substrate 1 on the hot plate 51 from an arbitrary predetermined baking temperature is not limited to 90 ° C., 110 ° C., 130 ° C., and 150 ° C. it can.

(Preparation of substrate)
First, a mask substrate 1 for preparing a master mold 20 to be a nanoimprint mold is prepared (FIG. 1A). The mask base plate 1 is a mask base plate made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches.
As long as this mask base plate 1 can be used as the master mold 20, its shape and material are not limited. Moreover, the shape of the base plate 1 will not be ask | required if a process with the baking processing apparatus 50 is possible.
On the other hand, the mask substrate 1 is transferred from the first hot plate 51 to the second hot plate 52 when baking is performed by the baking processing apparatus 50 described in the above embodiment. In the inside, that is, the first hot plate 51 is made of a material and a thickness showing a behavior in which the surface temperature does not decrease immediately after the mask substrate 1 leaves. For example, in the case of the wafer, while the mask substrate 1 is being transferred from the first hot plate 51 to the second hot plate 52, the wafer leaves the first hot plate 51 and at the same time, Since surface temperature will fall, it is not suitable for the object of the processing board of the present invention.
In the present embodiment, description will be made using a mask substrate 1 made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches according to a standard for manufacturing a photomask.

(Formation of hard mask layer on substrate)
First, the mask substrate 1 (FIG. 1 (a)), which is appropriately polished and cleaned as necessary, is introduced into a sputtering apparatus. In the present embodiment, a target made of chromium (Cr) is sputtered with argon gas and nitrogen gas to form a hard mask film 2 made of chromium nitride (FIG. 1B).

  Note that the hard mask film 2 in this embodiment is composed of a single layer or a plurality of layers, and the hard mask film 2 in a portion corresponding to a groove (hereinafter referred to as a groove portion) of the resist pattern 4 described later is removed by etching. Thereafter, it refers to a film that acts as a mask material when the mask substrate 1 is etched to form a groove portion, and can protect portions other than the groove portion. Here, the hard mask film 2 preferably has good adhesion to the resist film 3. The hard mask film 2 preferably has good etching selectivity with the resist film 3. Further, the film thickness of the hard mask film 2 is preferably a thickness that remains until the etching for forming the groove in the mask substrate 1 is completed.

(Application of chemically amplified resist)
The mask substrate 1 on which the hard mask film 2 is formed is appropriately washed as necessary, and after baking treatment as a measure for improving adhesion, in the present embodiment, as shown in FIG. As shown, a chemically amplified resist is applied to the mask substrate 1. As a coating method, in this embodiment, a spin coating method is used in which a resist solution is dropped and applied from above the mask substrate 1 while rotating at a predetermined rotational speed. Thus, a chemically amplified resist film 3 (hereinafter also referred to as resist film 3) is formed on the mask substrate 1. Before providing the resist film 3, an adhesion layer may be provided on the mask substrate 1 on which the hard mask film is formed, and the resist film 3 may be provided thereon.

The chemically amplified resist may be a known one. What is necessary is just to have reactivity when irradiated with an energy beam. Specifically, any resist that needs to perform PAB and PEB processing may be used.
In addition, the thickness of the resist film 3 at this time is preferably such that it remains until etching on the mask substrate 1 is completed. This is because not only the mask substrate 1 but also the resist film 3 is removed at the time of etching.
Note that a plurality of resist films 3 may be provided. For example, a resin film that is not sensitive to an electron beam may be separately applied to the lower layer of the resist film 3, and the resist film 3 made of a chemically amplified resist may be formed thereon.

(PAB processing)
Specifically, the PAB process is performed as follows by the bake processing apparatus 50 (see FIG. 2) configured and prepared as described above. First, the mask substrate 1 on which the hard mask film 2 and the chemically amplified resist film 3 are formed is placed on the upper surface of the hot plate 51 adjusted and held at a predetermined temperature, and is left still for a predetermined time with the spacer interposed therebetween. Is done.

Here, the temperature of the hot plate 51 is higher than the temperature of the hot plate 52. Further, the rate of temperature rise on the surface of the mask substrate after the start of baking by the hot plate 51 is calculated by dividing a predetermined baking processing temperature for the chemically amplified resist to be baked by a predetermined baking processing time at the time of resist design development. The temperature of the hot plate 51 is set so as to be larger than the above value. For example, when the predetermined baking time is set to 90 seconds and the predetermined baking temperature is set to 130 ° C., the hot plate 51 is set so that the temperature rising rate can be 1.44 ° C./second or higher. Determine and hold temperature.
In addition, when the transfer of the mask substrate 1 is completed and the standing is started, a timer is started, and the mask substrate 1 is left on the hot plate 51 for a predetermined time determined according to the determination method described above. .

The mask substrate 1 that has been allowed to stand for a predetermined time on the hot plate 51 is continuously adjusted and held so that the temperature of the surface of the mask substrate 1 becomes the same as the predetermined baking temperature suitable for the resist 3, It is transferred to the upper surface and the surface, and is allowed to stand for a predetermined time with the spacer interposed therebetween.
Then, from the point of time when the mask substrate 1 is transferred to the hot plate 51 and is allowed to stand still, the total PAB processing time in which the mask substrate 1 is transferred to the hot plate 52 and allowed to stand, that is, to the hot plate 51 is set. When the total of these times reaches 90 seconds, the mask substrate 1 is separated from the hot plate 52. .

Next, the mask substrate 1 is continuously transferred to a cooling plate 53 adjusted and held at 12.5 ° C. and allowed to stand. Thereafter, the mask substrate 1 is allowed to stand on the cooling plate 53 until the temperature reaches room temperature, and the PAB process ends.
By this PAB treatment, the solvent remaining in the resist film 3 can be removed and the resist film 3 can be made dense.

(Pattern drawing)
Next, a desired pattern is drawn on the mask substrate 1 (that is, the chemically amplified resist film 3) that has been subjected to the PAB process using an electron beam drawing machine.

  The fine pattern drawn here may be on the micron order, but may be on the nano order from the viewpoint of the performance of electronic devices in recent years, or the performance of the final product produced by a nanoimprint mold or the like. That is preferable.

If the resist film 3 is a positive chemically amplified resist, the portion where the electron beam is drawn is dissolved and removed by the development process, and the portion corresponds to the position of the groove of the mold 20 to be completed. On the other hand, if the resist layer is a negative resist, the electron beam drawn portion remains after the development process, and the portion corresponds to a position other than the groove of the mold 20 to be completed.
In the present embodiment, when a positive resist is used, that is, the drawing portion on the resist film 3 corresponds to the position of the groove in the mold 20.
Here, an example of the composition of the chemically amplified resist is a chemically amplified resist comprising a polyhydroxystyrene (PHS) resin and an onium salt acid generator.

(PEB treatment)
Next, post-exposure baking (PEB) is performed on the mask substrate 1 having the resist film 3 after pattern drawing. This PEB process is performed in the same manner as described below by the bake processing apparatus 50 (see FIG. 2) configured and prepared as described above, just like the PAB process.

First, the hard mask film 2 and the chemically amplified resist film 3 are formed, and the mask substrate 1 subjected to the drawing is transferred to the upper surface of the hot plate 51 adjusted and held at a predetermined PEB temperature, with the spacer interposed therebetween, Let stand for a predetermined time.
Here, the temperature of the hot plate 51 is higher than the temperature of the hot plate 52. Further, the temperature increase rate of the surface of the mask substrate 1 after the start of baking by the hot plate 51 is the predetermined baking process temperature for the chemically amplified resist film 3 to be baked. The temperature of the hot plate 51 is adjusted and held so as to be larger than the value divided by the time. For example, the set temperature of the hot plate 51 is set so that the predetermined baking process time is 90 seconds, the predetermined baking temperature is 130 ° C., and the rate of temperature increase is 1.44 ° C./second. Determine and hold adjustment.
In addition, when the transfer of the mask substrate 1 is completed and the standing is started, a timer is started, and the mask substrate 1 is left on the hot plate 51 for a predetermined time determined according to the determination method described above. .

The mask substrate 1 that has been allowed to stand on the hot plate 51 for a predetermined period of time is continuously adjusted and held so that the temperature of the mask substrate surface is the same as the predetermined baking temperature suitable for the resist film 3; It is moved to the upper surface, and left still for a predetermined time with the spacer in between.
Then, the total PEB processing time in which the mask substrate 1 is transferred to the hot plate 52 and left standing after the mask substrate 1 is transferred to the hot plate 51 and left standing, that is, the hot plate 51 is set. When the total of these times reaches 90 seconds, the mask substrate 1 is moved from the hot plate 52 to the hot plate 52. Release.

  Next, the mask substrate 1 is continuously transferred to a cooling plate 53 adjusted and held at 12.5 ° C. and allowed to stand. Thereafter, the mask substrate 1 is allowed to stand on the cooling plate 53 until it reaches room temperature, and the PEB process is completed.

  By this PEB treatment, the acid generated from the acid generator by the drawing is thermally diffused, and the protective groups of the resist film 3 are removed in a chain manner, and the electron beam-drawn portion of the resist film 3 becomes the developer. It changes so that it can be dissolved.

(developing)
After a desired fine pattern is drawn with an electron beam, as shown in FIG. 1D, the resist film 3 is developed with a predetermined developer, and the portion of the resist film 3 on which the electron beam is drawn (resist dissolving portion) is removed. Then, a resist pattern 4 corresponding to a desired fine pattern is formed.
A known developer may be used as the developer. As an example, a developer using a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) may be mentioned. The developer is sprayed on the mask substrate 1 for 60 seconds, for example, and the development process ends.

(rinse)
Thereafter, the mask substrate 1 having the resist pattern 4 is processed by spraying a rinse agent from above the mask substrate 1 while rotating the mask substrate 1 in order to wash away the developer. This rinse agent may be pure water. Alternatively, in order to reduce the surface tension, a surfactant or the like is added to pure water and used as a rinsing agent, or an organic solvent having a small surface tension or the like is used as a rinsing agent. Can be suppressed or reduced. The rinse solution may be a poor solvent for the resist pattern 4.

(Dry)
A drying process is performed on the mask substrate 1 on which the resist pattern 4 subjected to the rinsing process is formed. This drying process is performed by stopping the supply of the rinse agent after the rinsing process and rotating the mask substrate 1 at a predetermined rotational speed. As a result, the rinse agent flows down from the outer edge of the substrate or evaporates due to centrifugal force. In this way, a desired resist pattern 4 composed of the resist dissolving portion and the resist non-dissolving portion is formed. Moreover, the mask substrate 1 with the hard mask film 2 on which the resist pattern 4 is formed is obtained.
It is to be noted that, for the purpose of removing the developer or rinse agent remaining in the formed resist pattern 4 and improving the adhesion between the resist pattern 4 and the hard mask film 2, drying is performed as necessary. A baking process may be performed following the process.

(Descum of resist pattern: first etching)
Thereafter, the mask substrate 1 with the hard mask film 2 on which the resist pattern 4 is formed is introduced into a dry etching apparatus. Then, first etching with a mixed gas of oxygen gas and argon (Ar) gas is performed to remove the residue (scum) of the resist dissolution portion. Here, instead of the oxygen gas, for example, a fluorine-based gas such as CH ₄ may be used. Further, helium (He) may be added.

(Hard mask layer etching: second etching)
Subsequently, after exhausting the gas used in the first etching, the second etching is performed with a mixed gas composed of chlorine gas and oxygen gas, and the hard mask film exposed by the development process and the first etching process is performed. 2 is removed.
Thus, as shown in FIG. 1E, a groove corresponding to the resist pattern 4 is applied to the hard mask film 2 on the mask substrate 1.
Note that the etching end point at this time is determined by using, for example, a reflection optical end point detector or a plasma monitor.

(Substrate etching: third etching)
Subsequently, after exhausting the gas used in the second etching, a third etching using a fluorine-based gas is performed on the mask substrate 1.

  Thus, as shown in FIG. 1 (f), the groove 20 corresponding to the resist pattern 4 is applied to the mask substrate 1, and the hard mask film 2 remaining except the groove and the mold 20 before the remaining resist pattern 4 is removed. Is produced.

Note that as the fluorine-based gas used here, C _x F _y (for example, CF ₄ , C ₂ F ₆ , C ₃ F ₈ ), CHF ₃ , a mixed gas thereof, or a rare gas (He, Ar, Xe, etc.) are included.

(Removal of resist pattern)
Subsequently, the remaining resist pattern 4 generated after the third etching is removed by a resist stripper composed of a mixed solution of sulfuric acid and hydrogen peroxide solution, and the resist pattern 4 is completely stripped and removed.
Specifically, the mask substrate 1 is immersed in the resist remover for a predetermined time, and then the resist remover is washed away with a rinse agent (in this case, room temperature or heated pure water). Next, the mask substrate 1 is dried by the same method as the drying process.
In addition, as a resist remover used here, an organic solvent, ozone water, etc. other than the liquid mixture of the said sulfuric acid and hydrogen peroxide solution are mentioned. Any compound that can swell and dissolve or chemically decompose and remove the resist can be used. Further, these resist stripping agents may be heated to enhance the resist stripping / removing ability. Furthermore, an ashing process using oxygen plasma may be used.
The resist pattern 4 may be removed after the second etching process and before the third etching process.

(Removal of hard mask film: fourth etching)
Subsequently, the hard mask film 2 patterned corresponding to the resist pattern 4 remaining on the mold 20 before the remaining hard mask film 2 is removed by the same method as the first etching is dry-etched. The process of peeling and removing is performed. Note that when there is a chemical that can dissolve and remove the hard mask film (for example, a chromium nitride (CrN) film), the hard mask film may be removed by wet etching.

  After the above steps, if necessary, the mask substrate 1 is cleaned up to the removal of the hard mask. Thus, the nanoimprint mold 20 (master mold) as shown in FIG. 1G is completed.

In the present embodiment as described above, the following effects can be obtained.
That is, according to the baking processing apparatus of the present invention, even if it is a mask substrate made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches, the chemically amplified resist film applied to the substrate It is possible to perform processing at a predetermined baking temperature within the baking processing time at the time of design development or trial manufacture of the chemically amplified resist. As a result, it is possible to avoid excessively baking the chemically amplified resist film, maintain a high residual film ratio for the undrawn portion, and ensure a high pattern contrast, thereby forming a high-quality resist pattern. Can be provided. In addition, a high-quality photomask and nanoimprint mold can be produced and provided using the high-quality resist pattern.

  The baking apparatus, the chemically amplified resist pattern forming method, and the nanoimprint mold and photomask manufacturing method in the first embodiment can be suitably applied to the following applications in addition to the nanoimprint mold manufacturing applications. . For example, LCD photomasks, semiconductor manufacturing, microelectromechanical systems (MEMS), sensor elements, optical disks, optical components such as diffraction gratings and polarizing elements, nanodevices, organic transistors, color filters, microlens arrays, immunoassay chips, It can be widely applied to the production of DNA separation chips, microreactors, nanobiodevices, optical waveguides, optical filters, photonic crystals, and the like.

  As mentioned above, although embodiment which concerns on this invention was mentioned, said disclosure content shows exemplary embodiment of this invention. The scope of the present invention is not limited to the exemplary embodiments described above. Whether or not explicitly described or suggested herein, those skilled in the art will make various modifications to the embodiments of the present invention based on the disclosure of the present specification. Can be implemented.

  Next, an Example is shown and this invention is demonstrated concretely. Of course, the present invention is not limited to the following examples.

<Example 1>
In this example, a mask substrate made of synthetic quartz having a size of 6 inches square and a thickness of 0.250 inches was used as the mask substrate 1 (FIG. 1A).
First, the mask substrate 1 was introduced into a sputtering apparatus, and a target made of chromium (Cr) was sputtered with argon gas and nitrogen gas to form a hard mask film 2 made of chromium nitride having a thickness of 2 nm (FIG. 1B). )).

  Next, the mask substrate 1 on which the hard mask film 2 was formed was set on a resist coater. Then, about 3 ml of a positive chemically amplified resist composed of a polyhydroxystyrene resin and an onium salt acid generator as a solution using PGMEA as a solvent is dropped on the mask substrate 1, and then 60 rpm at 1500 rpm. The mask substrate 1 was rotated for 2 seconds to apply the resist film 3 to a film thickness of 50 nm.

Here, the hot plate 51, the hot plate 52, and the cooling plate 53 are sequentially arranged in order,
Further, a transport mechanism 54 for transporting the mask substrate 1, which is placed on the hot plate 51, the hot plate 52, and the cooling plate 53 in this order and at different standing times and then transferred, is provided. A prepared bake processing apparatus was prepared.
Here, the hot plate 51 is adjusted and held at 225 ° C., and the hot plate 52 is heated at the baking temperature of the positive chemically amplified resist when the mask substrate 1 is transferred to the hot plate 52 and allowed to stand. The temperature was appropriately adjusted and maintained so that the substrate surface temperature was 130 ° C.
Next, the temperature of the cooling plate 53 was maintained at 12.5 ° C.
Further, on the upper surfaces (surfaces) of the hot plate 51, the hot plate 52, and the cooling plate, a heat-resistant resin tape made of polyimide having a thickness of 100 μm is disposed at a position located on the substantially outer periphery of the mask substrate 1, and spacers are provided. It was.

  As described above, the hot plate 51 is adjusted and held at 225 ° C., and when the mask substrate 1 is placed on the hot plate 52, the surface of the mask substrate 1 becomes 130 ° C. 52 was adjusted and held at 145 ° C. The cooling plate was adjusted and held at 12.5 ° C.

Next, a mask substrate 2 for measuring the substrate surface temperature was prepared, in which 25 thermocouples were disposed evenly (5 × 5, interval 25 mm) in the range of the central 125 mm square of the surface of the mask substrate 1.
Then, the mask substrate 2 is baked using the bake processing apparatus prepared with the temperature setting, and the PAB process or PEB process of the temporary dressing is performed, and the surface temperature of the mask substrate 2 and the bake process at that time The relationship with the passage of time was sought. At that time, the elapsed time immediately after the mask substrate 2 is transferred onto the hot plate 51 and allowed to stand (hereinafter referred to as standing time 1) is changed from 10 seconds to 45 seconds to 45 seconds. It was.
Here, FIG. 3 is an example of the result of obtaining the relationship between the surface temperature of the mask substrate 2 and the lapse of time of the baking process.
As shown in FIG. 3, when the standing time 1 is set to 40 seconds, the surface temperature of the mask substrate 2 does not exceed a predetermined baking temperature of 130 ° C., and rapidly reaches the 130 ° C. Has reached.
On the other hand, as the standing time 1 is shortened to 35 seconds or shorter, the surface temperature of the mask substrate 2 gradually increases as the surface temperature of the mask substrate 2 approaches the predetermined baking temperature of 130 ° C. As a result, the time for the surface temperature of the mask substrate 2 to reach the predetermined baking temperature of 130 ° C. was delayed. On the other hand, as the standing time 1 is increased to 45 seconds or longer, the surface temperature of the mask substrate 2 overshoots exceeding the predetermined baking temperature of 130 ° C.
From the above results, when the hot plate 51 was adjusted and maintained at 225 ° C. and the spacer thickness was 100 μm, the standing time 1 on the hot plate 51 was determined to be 40 seconds in advance.
By setting the standing time 1 to 40 seconds, the surface of the mask substrate 2 reached a predetermined baking temperature of 130 ° C. in about 60 seconds.
In addition, the surface temperature of the mask substrate 2 measured using the mask substrate 2 was obtained by obtaining an average value of the temperature display values of the 25 thermocouples as a representative value.

Next, the chemically amplified resist and the spin-coated mask substrate 1 were subjected to PAB treatment.
Similar to the baking process of the mask substrate 2, the hot plate 51 is adjusted and held at 225 ° C., and the surface of the mask substrate 1 becomes 130 ° C. when the mask substrate 1 is placed on the hot plate 52. Thus, the hot plate 52 was adjusted and held at 145 ° C. The cooling plate was adjusted and held at 12.5 ° C.
Then, the mask substrate 1 was first transferred to the hot plate 51 and allowed to stand by the transport mechanism 54. Then, the timer is started simultaneously with the start of the standing, and when 40 seconds have passed since the standing is started, the mask substrate 1 is transferred to the hot plate 52 by the transport mechanism 54 and is allowed to stand. I put it. At this time, the time required for transferring the mask substrate 1 from the hot plate 51 to the hot plate 52 (hereinafter referred to as transfer time 1) was 15 seconds. Therefore, 55 seconds obtained by adding 40 seconds of the standing time 1 and 15 seconds of the transfer time 1 are subtracted from the desired baking time of 90 seconds to leave the mask substrate 1 on the hot plate 52 (standing time). 2) was 35 seconds.
Then, when 35 seconds of the standing time 2 have elapsed, the mask substrate is transferred to the cooling plate 53 by the transport mechanism 54 and left still, and the mask substrate 1 having a surface temperature of 130 ° C. is room temperature. After 150 seconds had passed until the substrate was cooled, the mask substrate 1 was taken out of the cooling plate 53 by the transport mechanism 54 to complete the PAB process.

  Next, a 200 μm square pattern was drawn with an electron beam drawing apparatus (Elionix, ELS-3700) with an acceleration voltage of 20 kV. At this time, the exposure amount was from 0.5 μC / cm 2 to 10 μC / cm 2, and an interval of 0.25 μC / cm 2 was used to draw a total of 39 rectangular patterns.

After drawing, the mask substrate 1 was subjected to PEB treatment.
As in the PAB process, the hot plate 51 is adjusted and held at 225 ° C., and the mask substrate 1 is hot so that the surface of the mask substrate 1 becomes 130 ° C. when the mask substrate 1 is placed on the hot plate 52. The plate 52 was adjusted and held at 145 ° C. The cooling plate was adjusted and held at 12.5 ° C.
Then, the mask substrate 1 was first transferred to the hot plate 51 and allowed to stand by the transport mechanism 54. Then, the timer is started simultaneously with the start of the standing, and when 40 seconds have passed since the standing is started, the mask substrate 1 is transferred to the hot plate 52 by the transport mechanism 54 and is allowed to stand. I put it. At this time, the time required for transferring the mask substrate 1 from the hot plate 51 to the hot plate 52 (hereinafter referred to as transfer time 1) was 15 seconds. Therefore, 55 seconds obtained by adding 40 seconds of the standing time 1 and 15 seconds of the transfer time 1 are subtracted from the desired baking time of 90 seconds to leave the mask substrate 1 on the hot plate 52 (standing time). 2) was 35 seconds.
Then, when 35 seconds of the standing time 2 have elapsed, the mask substrate is transferred to the cooling plate 53 by the transport mechanism 54 and left still, and the mask substrate 1 having a surface temperature of 130 ° C. is room temperature. After 150 seconds had passed until the substrate was cooled, the mask substrate 1 was taken out of the cooling plate 53 by the transport mechanism 54 and the PEB process was completed.

Thereafter, the resist film 3 subjected to the electron beam drawing on the mask substrate 1 was developed with a 2.38% TMAH aqueous solution for 60 seconds by a rotary spray developing apparatus. After the development, while the mask substrate 1 was rotated at 250 rpm, pure water was sprayed for 60 seconds as a rinsing solution for rinsing treatment.
Thereafter, the mask substrate 1 was rotated at 1500 rpm to perform a drying process. Thus, a resist pattern of a chemically amplified resist, which is a sample according to the example, was formed on the mask substrate 1.

  A residual film sensitivity curve was obtained for the sample according to Example 1. Specifically, after finishing the electron beam drawing and PEB processing, the resist film thickness (film thickness before development processing) is measured with a spectral reflection type film thickness measuring machine, and after the development processing is finished, the 39 For each 200 μm square pattern, the remaining film thickness after the development processing at that location is measured, and compared with the film thickness before the development processing, the remaining film rate is calculated, and the remaining film rate and the electron beam irradiation amount The residual film sensitivity curve which is the relationship was obtained. Further, the remaining film ratio and contrast (γ value) of the undrawn part after the development processing were obtained. These results are shown in FIGS. 4A and 4B.

<Example 2>
In Example 2, the sample according to Example 2 is the same as Example 1 except that the electron beam drawing pattern is a 50 nm line and space pattern instead of the 200 μm square pattern of Example, that is, A resist pattern 4 of the positive chemically amplified resist was formed.
Furthermore, in Example 2, in accordance with the first embodiment, the resist pattern 4 is discamed, the hard mask film 2 is etched, the mask substrate 1 is etched, the resist pattern is removed, and the hard mask film is removed. Was made.

<Comparative example>
In Example 1, the hot plate 51 is adjusted and held at 225 ° C., the hot plate 52 is adjusted and held at 145 ° C., the cooling plate 53 is adjusted and held at 12.5 ° C., and the standing time 1 is set to 40. Second, the standing time 2 is 35 seconds, the transfer time 1 between the hot plate 51 and the hot plate 52 is 15 seconds, and the mask substrate 1 is baked at 130 ° C. for 90 seconds as the PAB and PEB treatment. The resist pattern was formed by processing.
In Comparative Example 1, both the hot plate 51 and the hot plate 52 were adjusted and held at 145 ° C. so that the surface temperature of the mask substrate 1 became 130 ° C. when the mask substrate 1 was transferred and allowed to stand. The sample was the same as in Examples 1 and 2 except that the standing time 1 and the standing time 2 were 300 seconds, the transfer time 1 was added 15 seconds, and the PAB treatment and the PEB treatment were performed for a total of 615 seconds. Was made.
The remaining film sensitivity curve, γ value, and remaining film rate were also investigated in the same manner as in Example 1.

<Evaluation>
In Example 1, as shown in FIG. 4A, the remaining film ratio of the unexposed part was good in both the pattern contrast (γ value).
On the other hand, in Comparative Example 1, as shown in FIG. 4B, the remaining film ratio and the pattern contrast (γ value) of the unexposed part were significantly inferior to Example 1.

DESCRIPTION OF SYMBOLS 1 Mask substrate 2 Hard mask film 3 Resist film 4 Resist pattern 10 Residual hard mask and mold before removal of residual resist pattern 20 Imprint mold (master mold)
50 Bake processing device 51, 52 Hot plate 53 Cooling plate 54 Conveying mechanism 55 Tape

Claims (15)

On the substrate for producing a photomask or nanoimprint mold,
A baking apparatus for applying a chemically amplified resist, and then performing a post-application baking process,
And / or a baking apparatus for forming a resist film by applying the resist, performing post-application baking, and performing post-exposure baking on the substrate having the resist film on which a desired pattern is drawn. And
A baking processing apparatus comprising a plurality of continuous hot plates and a single or a plurality of cooling plates.   2. The baking processing apparatus according to claim 1, wherein the substrate is a synthetic quartz having a 6 inch square and a thickness of 0.250 inch. Of the plurality of consecutively arranged hot plates, the first hot plate that first transfers the substrate and rests and starts the baking process is a predetermined baking temperature of the resist to be baked. Is set to a high temperature,
Subsequent to the baking process on the first hot plate, the second or second hot plate after the substrate is transferred and allowed to stand and the resist baking process is continued is performed on the second hot plate. The baking processing apparatus according to claim 1 or 2, wherein the baking temperature is set to a predetermined baking temperature of the resist to be processed.   First, the substrate is transferred and allowed to stand to start the baking process. The temperature rise rate (Ramp) of the surface of the substrate after the start of baking by the first hot plate is determined for the resist to be baked. The predetermined baking temperature (Temp) is larger than the value obtained by gradual baking time (Time) at the time of resist design development (Ramp)> ((Temp) / (Time)). 3. The baking processing apparatus according to 3.   The baking time (BakeTime) from when the substrate is transferred to the first hot plate and allowed to stand to start the baking process and until the final hot plate is left is determined at the time of resist design development. 5. The baking processing apparatus according to claim 1, wherein (BakeTime) ≦ (Time Origin) does not exceed the baking processing time (Time Origin).   The time of standing after the substrate is transferred to the first hot plate (standing time 1) is the maximum temperature that the surface of the mask substrate reaches during post-application baking or post-exposure baking. 6. The baking processing apparatus according to claim 1, wherein a relationship with said standing time 1 is determined in advance and determined.   7. The apparatus according to claim 1, wherein, following the plurality of continuously arranged hot plates, at least one of the one or more cooling plates is set and maintained at a temperature that does not cause condensation near the dew point. The baking processing apparatus as described. On the substrate for producing a photomask or nanoimprint mold,
A resist pattern forming method in which a chemically amplified resist is applied, followed by baking after application,
And / or a resist pattern forming method in which a resist film is formed by coating the resist, followed by a baking process after coating, and performing a post-exposure baking process on the mask substrate having the resist film on which a desired pattern is drawn. Because
The treatment of the substrate is a step of continuously using at least two or more of the hot plates arranged in succession and transferring the substrate to the first hot plate and leaving it stationary,
A step of transferring the substrate which has been transferred to the first hot plate and allowed to stand to the second plate or the second or subsequent hot plate to be left and performing a baking process;
Continuing the baking process, transferring the mask substrate to a single or a plurality of cooling plates and allowing them to stand and cool,
A resist pattern forming method characterized by comprising: Of the plurality of consecutively arranged hot plates, the first hot plate that first transfers the substrate and rests and starts the baking process is a predetermined baking temperature of the resist to be baked. Is set to a high temperature,
Subsequent to the baking process on the first hot plate, the second or second and subsequent hot plates in which the substrate is transferred and allowed to stand and the resist baking process is continued are baked. 9. The resist pattern forming method according to claim 8, wherein the resist pattern forming method is set to a predetermined baking temperature for the resist.   First, the substrate is transferred and allowed to stand to start the baking process. The temperature rise rate (Ramp) of the surface of the substrate after the start of baking by the first hot plate is determined by the resistance of the chemically amplified resist to be baked. (Ramp)> ((Temp) / (Time)), which is larger than a value obtained by dividing a predetermined baking processing temperature (Temp) for dividing by a baking processing time (Time) at the time of resist design development. The resist pattern forming method according to 8 or 9.   The baking time (BakeTime) from when the substrate is transferred to the first hot plate and allowed to stand to start the baking process and after the final hot plate is left is determined at the time of resist design development. 11. The method of forming a resist pattern according to claim 8, wherein (BakeTime) ≦ (Time Origin) that does not exceed the baking time (Time Origin).   The time of standing after the substrate is transferred to the first hot plate (standing time 1) is the maximum temperature at which the surface of the mask substrate reaches during the post-application baking process or post-exposure baking process. 12. The method for forming a resist pattern according to claim 8, wherein the relationship with the standing time 1 is determined in advance and determined.   The at least one of the one or more cooling plates following the plurality of consecutively arranged hot plates is set and maintained at a temperature that does not cause condensation near the dew point. The resist pattern formation method of description. To a substrate made of synthetic quartz with a size of 6 inches square and a thickness of 0.250 inches,
A method of manufacturing a photomask in which a chemically amplified resist is applied and then a baking process is performed after the application,
And / or a method of manufacturing a photomask for forming a resist film by applying the resist, performing a post-application baking process, and performing a post-exposure baking process on the substrate having the resist film on which a desired pattern is drawn Because
The processing of the substrate is a step of continuously using at least two or more of the hot plates arranged continuously and transferring the mask substrate to the first hot plate,
A step of transferring the substrate which has been transferred to the first hot plate and allowed to stand to the second plate or the second or subsequent hot plate to be left and performing a baking process;
Continuing the baking process, the step of transferring the substrate to a single or a plurality of cooling plates, leaving the substrate stationary, and cooling,
A method for producing a photomask, comprising: To a substrate made of synthetic quartz with a size of 6 inches square and a thickness of 0.250 inches,
A method for producing a mold for nanoimprint, in which a chemically amplified resist is applied and then a baking process is performed after the application,
And / or forming a resist film by coating the resist, then performing a baking process after coating, and manufacturing a nanoimprint mold for performing a post-exposure baking process on the substrate having the resist film on which a desired pattern is drawn A method,
The treatment of the substrate is a step of continuously using at least two or more of the hot plates arranged in succession and transferring the substrate to the first hot plate and leaving it stationary,
A step of transferring the substrate which has been transferred to the first hot plate and allowed to stand to the second plate or the second or subsequent hot plate to be left and performing a baking process;
Continuing the baking process, the step of transferring the substrate to a single or a plurality of cooling plates, leaving the substrate stationary, and cooling,
The manufacturing method of the mold for nanoimprint characterized by having.