JP2013113999A - Method for manufacturing mold and resist processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a mold and a resist processing method, by which a recessed portion having a predetermined width is formed as designed even when a rugged pattern to be formed on a main surface is fine.SOLUTION: The resist processing method for processing a resist pattern with recesses and projections includes a width enlarging step for a recessed portion of a resist pattern, in which a resist pattern having a width of an opening of the recessed portion smaller than a predetermined width in the resist pattern is sharpened to enlarge the width of the recessed portion in the resist pattern. The recessed portion width enlarging step includes: a first step of enlarging the width of the opening of the recessed portion in the resist pattern to be a width substantially the same as the predetermined width; and a second step of sharpening the main surface portion of the recessed portion in the resist pattern in substantially a thickness direction to allow the width of the recessed portion in the resist pattern substantially to be the same as the width of the opening.

Description

  The present invention relates to a mold manufacturing method and a resist processing method, and more particularly to a mold manufacturing method in which a concavo-convex pattern including a concave portion having a predetermined width is formed, and a resist processing method for processing a resist pattern including the concavo-convex.

  Conventionally, in magnetic media used in hard disks and the like, a technique has been used in which magnetic particles are miniaturized, the magnetic head width is minimized, and data tracks on which information is recorded are narrowed to increase the recording density. On the other hand, there is an increasing demand for higher recording density, and in this magnetic medium, the magnetic influence between adjacent tracks cannot be ignored. For this reason, the conventional method has a limit in increasing the recording density.

  In recent years, a new type of media called patterned media in which data tracks of magnetic media are formed by magnetic separation has been proposed. This patterned medium is intended to achieve a higher recording density by removing (grooving) a magnetic material unnecessary for recording to improve signal quality.

  Recently, as this patterned medium, a type of medium called Discrete Track Recording Media (hereinafter referred to as DTR medium) in which data tracks of a magnetic disk are magnetically separated has been proposed. . This DTR media is excellent in S / N ratio (Signal-Noise Ratio) because the magnetic region and the non-magnetic region are physically separated by the groove.

  On the other hand, this DTR media has been developed with higher density and is called “bit patterned media” (magnetic media for recording signals as bit patterns (dot patterns) Bit Patterned Media; hereinafter referred to as BPM)). Some types of media have also been proposed.

  As a technique for mass-producing this patterned medium, there is a master mold (also referred to as a master) or a copy mold (also referred to as a working replica) that is transferred once or a plurality of times using the master mold as an original mold. An imprint technique (or nanoimprint technique) is known in which a patterned medium is produced by transferring a pattern to a transfer target (here, BPM).

  Many techniques have been proposed as techniques for producing the master mold. For example, the present applicant provides a hard mask layer on a substrate for producing a master mold, forms a resist layer on the hard mask layer, and then performs a predetermined pattern exposure and development on the resist layer. A technique for forming a predetermined concavo-convex pattern on a substrate by forming a resist pattern from the layer and etching the hard mask layer and the substrate using the resist pattern as a mask is disclosed (for example, Patent Document 1 and 2).

  On the other hand, the present applicant has also proposed a technique for producing a copy mold. As an example, in order to produce a further copy mold from a master mold or a master mold made of a copy mold, the uneven pattern of the master mold is transferred to the resist layer of the substrate, and then dry etching is further performed. A technique for performing dimensional variation is disclosed (Patent Document 3).

  In addition, a technique of using a resist in pattern formation when forming a semiconductor element is known instead of transferring an uneven pattern by imprint (for example, Patent Document 4). Patent Document 4 discloses a technique for performing an etching process on a resist pattern to reduce the overall size of the convex portion of the resist pattern, move the position, and correct a deviation of the resist pattern with respect to the design. ing.

JP 2011-96686 A WO2011 / 040476 JP 2011-156738 A Japanese Patent Laid-Open No. 10-98023

  In recent years, in the patterned media, it is required to reduce the period (pitch) of the pattern and thus the width of the concave portion and the convex portion in the concave / convex pattern. The required level of miniaturization increases with the passage of time. Taking BPM as an example, recently, a fine uneven pattern having a pattern period of 30 nm (concave: convex = 1: 1) is required. It has become.

  In order to satisfy this requirement, when producing BPM, it is necessary to refine the uneven pattern in the original mold. Furthermore, it is necessary to form a fine concavo-convex pattern on the master mold, which is a masterpiece of the original mold.

  However, the present inventors have grasped the following as problems when producing a master mold in which a concavo-convex pattern of the order of several tens of nm is formed. In the following description, when a resist layer is provided on a substrate and a positive resist is used for the resist layer (that is, the region exposed to the resist layer is removed by a development process to remove the resist pattern). (When it becomes a recess).

(Problem 1)
The resist layer on the substrate for producing the master mold is subjected to pattern exposure with an electron beam and developed. As a result, a resist pattern is formed on the substrate. However, the resist residual film that could not be removed by the development process may remain on the substrate. When removing this resist residual film, the portion that should originally remain as a resist pattern (the convex portion of the resist pattern) is also scraped, and the convex portion becomes extremely thin or disappears. Adjacent recesses communicate with each other, which may cause pattern defects. That is, since the width of the recess itself is small (for example, the width of the recess is 25 nm or less), and the period of the pattern is becoming fine (for example, a period of 50 nm or less), there has been little influence until now. The amount of residual resist film that should have been removed has a great influence on pattern formation.

(Problem 2)
When the resist pattern after the development process on the resist layer is observed in a plan view, even if a concave portion of the resist pattern having a predetermined diameter as designed is formed (FIG. 4A), after the resist residual film is removed When the resist pattern is observed in a plan view, a concave portion of the resist pattern having a diameter larger than a predetermined diameter is formed (FIG. 4B). Furthermore, if a concavo-convex pattern is formed on the main surface of the substrate in this state, a concave portion having a diameter smaller than a predetermined diameter is formed (FIG. 4C). In this case, the uneven pattern as designed cannot be formed in the first place, or even if it can be formed, it becomes very difficult, leading to a decrease in yield and an increase in cost.

In any patent document, the pattern period is less than 100 nm. Therefore, the above problems 1 and 2 cannot be obtained in the first place. Moreover, no means can be conceived from any patent document as means for solving the above-mentioned problems.
For example, in the case of Patent Document 3, there is no disclosure or suggestion about a means for eliminating the possibility of connection between the recesses, and neither disclosure nor suggestion about a means for eliminating the mismatch between the width of the opening and the bottom of the recess of the resist pattern. Absent.
In the case of Patent Document 4, it is described that the entire size of the convex portion of the resist pattern is reduced or the position is moved, but there is no disclosure or suggestion about the problem 2, and There is no disclosure or suggestion of means for solving the problem. In addition, regarding the removal of the resist residual film, there is only a description of the general content of etching removal of the bottom portion of the resist (paragraph 0007 of Patent Document 4). Note that “anisotropy” in Patent Document 4 refers to whether the etching is performed from the left or right direction when the convex portion of the resist pattern is viewed in cross section, as indicated by the arrow in FIG. This is different from cutting the main surface of the concave portion of the resist pattern “towards the thickness direction of the resist layer” in this specification.

  An object of the present invention is to provide a mold manufacturing method and a resist processing method in which a concave portion having a predetermined width is formed as designed even if an uneven pattern provided on a main surface is fine.

  The above-mentioned thing has been obtained by the present inventors as a problem when producing a master mold in which a concavo-convex pattern of the order of several tens of nm is formed. The present inventor examined the causes of the problems 1 and 2 described above. As a result, the following knowledge was obtained.

(Knowledge 1)
Regarding the problem 1, as described above, in recent years, it is required to form a fine uneven pattern in the patterned media. When the concavo-convex pattern becomes fine and the pattern period becomes small, adjacent exposure regions are very close to each other. Usually, a small amount of exposure is also performed on the convex portion (non-exposed region) of the resist pattern that should separate the concave portions. Since the exposure regions are very close to each other, the exposure amount at the convex portion of the resist pattern is accumulated. As a result, the convex portion of the resist pattern is exposed to a threshold amount or more, and the width and thickness of the convex portion of the resist pattern become smaller than expected during the development process. If the residual resist film is removed in this state, the convex portions of the resist pattern themselves are removed, and the concave portions of the resist pattern may communicate with each other.

(Knowledge 2)
Next, regarding the problem 2, FIGS. 4A to 4C shown above are photographs obtained by observing the resist pattern in a plan view. FIG. 5A is a schematic diagram when the resist pattern is viewed in cross section. ) To (c). 4A corresponds to FIG. 5A, and FIG. 4B corresponds to FIG. 5B.

  As shown in FIG. 5A, after the development process, the exposed region of the resist layer is selectively removed, and the recess 3a of the resist pattern 3 'is formed with a predetermined diameter.

  However, as shown in FIG. 5B, after the resist residual film is removed, the resist pattern 3 is removed at substantially the same removal rate (removal ratio) in the thickness direction of the resist layer and in the extending direction of the resist layer. It can be seen that the main surface of the recess 3a is removed. As a result, the opening 4 of the recess 3a of the resist pattern 3 'has a diameter larger than a predetermined diameter, and the plan view is as shown in FIG. 4B. On the other hand, the diameter of the portion near the substrate 2 (hereinafter also referred to as the bottom 5) in the recess 3a of the resist pattern 3 ′ and the portion of the substrate 2 corresponding to the recess 3a of the resist pattern 3 ′ (that is, exposed in the substrate 2). The diameter of the exposed portion 6), which is the portion that has been formed, is smaller than a predetermined diameter, and finally, when the concave and convex pattern is formed on the main surface of the substrate 2, a plan view is shown in FIG. .

  As described above, the present inventors faced an unprecedented problem of forming an extremely fine uneven pattern of the order of several tens of nanometers. The cause of this problem is the accumulation of the exposure amount in the non-exposed areas due to the pattern miniaturization. This is due to the fact that the diameter of the opening is larger than the diameter of the bottom in the concave portion of the resist pattern after removal of the resist residual film (Knowledge 2). The inventor found out.

  Based on the above knowledge, as a means for solving the above problems, the present inventor first intentionally makes the width of the recess 3a of the resist pattern 3 ′ smaller than the design, and then the thickness of the resist layer. The main surface of the concave portion 3a of the resist pattern 3 ′ is scraped at substantially the same removal speed in the direction and the extending direction of the resist layer, and the width of the opening 4 of the concave portion 3a is expanded to a predetermined width. 1 step (FIG. 3 (b-1)), and then, by shaving the main surface of the recess 3a in the thickness direction of the resist layer (that is, the removal rate in the thickness direction of the resist layer is particularly increased), Finally, it was conceived that the second step (FIG. 3B-2) in which the bottom 5 of the recess 3a (and thus the exposed portion 6 in the substrate 2) has a predetermined width was performed.

The present invention has been made based on the above-described findings.
The first aspect of the present invention is:
In a method of manufacturing a mold for forming a recess having a predetermined width and pattern on the main surface of a substrate,
A resist layer forming step of forming a resist layer on the substrate;
A pattern exposure step of performing pattern exposure by irradiating the resist layer with an energy beam;
Developing the resist layer that has been subjected to pattern exposure, and forming a resist pattern comprising irregularities; and a resist pattern forming step,
A resist pattern recess width expanding step of expanding the width of the recess of the resist pattern by scraping the resist pattern;
Have
In the pattern exposure step, pattern exposure is performed so that the width of the concave portion of the resist pattern is smaller than the predetermined width,
The resist pattern recess width expanding step,
A first step of expanding the width of the opening of the recess in the resist pattern to a width substantially the same as the predetermined width;
A second step of making the width of the concave portion of the resist pattern substantially the same as the width of the opening by scraping a portion of the main surface of the concave portion in the resist pattern substantially in the thickness direction;
It is the manufacturing method of the mold characterized by having.
According to a second aspect of the present invention, in the invention according to the first aspect,
The resist layer is a positive resist,
In the pattern exposure step, the width of the irradiation region of the energy beam with respect to the resist layer is made smaller than the predetermined width.
According to a third aspect of the present invention, in the invention according to the first or second aspect,
The second step is a step of exposing a portion of the substrate corresponding to the concave portion of the resist pattern, and the width of the portion is set to be substantially the same as the predetermined width. And
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects,
The width of the concave portion of the resist pattern enlarged by the first step is a width that does not overlap with the concave portion of the adjacent resist pattern.
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects,
The concave portions provided on the main surface of the substrate and the concave portions of the resist pattern are dot-shaped.
The sixth aspect of the present invention is:
In a mold manufacturing method for forming dot-shaped recesses having a predetermined diameter and pattern on the main surface of a substrate,
A resist layer forming step of forming a resist layer which is a positive resist on the substrate;
When irradiating the resist layer with an energy beam, a pattern exposure step of performing pattern exposure in a dot shape by making the diameter of the irradiation region smaller than the predetermined diameter; and
Developing the resist layer that has been subjected to pattern exposure, and forming a resist pattern comprising irregularities; and a resist pattern forming step,
A resist residual film removing step of removing the resist residual film on the portion corresponding to the dot-shaped concave portion of the resist pattern in the substrate;
Have
The resist residual film removing step includes
The diameter of the opening of the dot-shaped recess in the resist pattern is a diameter that does not overlap with the dot-shaped recess of the adjacent resist pattern, and expands to a diameter that is substantially the same as the predetermined diameter. 1 process,
By shaving the portion of the main surface of the dot-shaped recess in the resist pattern substantially in the thickness direction, the portion corresponding to the dot-shaped recess of the resist pattern is exposed in the base, A second step in which the diameter of the portion is substantially the same as the diameter of the opening and the predetermined diameter;
It is the manufacturing method of the mold characterized by having.
The seventh aspect of the present invention is
In the method of manufacturing a mold for processing a resist pattern composed of unevenness to form an uneven pattern on the main surface of the substrate,
A resist pattern preparation step of preparing a resist pattern composed of unevenness formed on the main surface of the substrate;
A resist pattern recess width expanding step of expanding the width of the recess of the resist pattern by scraping a resist pattern formed with a width of the opening of the recess in the resist pattern smaller than a predetermined width;
Have
The recess width expanding step includes:
A first step of expanding the width of the opening of the recess in the resist pattern to a width substantially the same as the predetermined width;
A second step of making the width of the concave portion of the resist pattern substantially the same as the width of the opening by scraping a portion of the main surface of the concave portion in the resist pattern substantially in the thickness direction;
It is the manufacturing method of the mold characterized by having.
The eighth aspect of the present invention is
In a resist processing method for processing a resist pattern consisting of irregularities,
A resist pattern recess width expanding step of increasing the width of the recess of the resist pattern by scraping a resist pattern formed with a width of the opening of the recess in the resist pattern smaller than a predetermined width;
The recess width expanding step includes:
A first step of expanding the width of the opening of the recess in the resist pattern to a width substantially the same as the predetermined width;
A second step of making the width of the concave portion of the resist pattern substantially the same as the width of the opening by scraping a portion of the main surface of the concave portion in the resist pattern substantially in the thickness direction;
A resist processing method characterized by comprising:

  ADVANTAGE OF THE INVENTION According to this invention, even if the uneven | corrugated pattern provided in a main surface is fine, the manufacturing method and resist processing method of a mold which form the recessed part which has a predetermined width | variety as designed can be provided.

It is sectional drawing which shows schematically the manufacturing process of the mold in this embodiment. It is a scanning electron microscope (SEM) photograph of the planar view with respect to a mold, (a) corresponds to Example 1, and the planar view of the resist pattern and the uneven pattern of the substrate when the pattern period in electron beam drawing is set to 35 nm. (B) corresponds to Example 2 and is a photograph when the pattern period is 30 nm. In (a) and (b), the upper photograph is a photograph of a resist pattern, and the lower photograph is a photograph of an uneven pattern of a substrate. It is the schematic at the time of carrying out the cross-sectional view of the resist pattern in Example 1, (a) is after development processing, (b-1) is after the 1st process in resist residual film removal, (b-2) is resist residual film. It is a figure which shows the mode after the 2nd process in removal. It is a scanning electron microscope (SEM) photograph of the planar view in each process which manufactures the mold in comparative example 1, (a) after development processing, (b) after resist residual film removal, (c) is uneven on a substrate. It is a photograph which shows the mode after forming a pattern. It is the schematic at the time of carrying out the cross-sectional view of the resist pattern in the comparative example 1, (a) is a figure which shows a mode after a development process, (b) after resist residual film removal. It is a scanning electron microscope (SEM) photograph of the planar view which shows the result about the pressure dependence of resist residual film removal in a reference example, (a) is the resist pattern after the development processing of Example 1, (b)-( d) is a photograph showing a resist pattern after removing the resist residual film by changing the pressure of the whole atmosphere, and the pressure of the whole atmosphere is 2.5 Pa in (b), 5.0 Pa in (c), (d ) Is 0.68 Pa. It is a scanning electron microscope (SEM) photograph which shows the result about the flow ratio dependency of resist residual film removal in a reference example. (A) is a plan view photograph when the flow rate ratio (Ar / O ₂ ) is 5 (= 100 sccm / 20 sccm), O ₂ is 16.7% by volume, and the pressure of the entire atmosphere is 0.68 Pa. (B) is a plan view photograph when the flow rate ratio (Ar / O ₂ ) is 2 (= 80 sccm / 40 sccm), O ₂ is 33.3% by volume, and the pressure of the whole atmosphere is 0.68 Pa. (C) shows the case where the residual resist film is removed at a flow rate ratio (Ar / O ₂ ) of 5 (= 100 sccm / 20 sccm), O ₂ of 16.7 vol%, and the pressure of the whole atmosphere is 2.5 Pa. It is the photograph which looked at resist pattern 3 '. On the other hand, (d) is a plan view photograph when the flow rate ratio (Ar / O ₂ ) is 2 (= 115 sccm / 5 sccm), O ₂ is 4.2 vol%, and the pressure of the whole atmosphere is 0.68 Pa. Yes, (e) is a perspective view of it. It is a scanning electron microscope (SEM) photograph of the planar view which shows the result about the time dependence in the 1st process in the resist residual film removal in a reference example, (a) is the resist pattern after the development processing of Example 1 (B) is a time that the thickness of the resist pattern 3 ′ can be cut by 18 nm, (c) is a time that can be cut by 28 nm, and (d) is a time that can be cut by 38 nm. It is a picture of the case. It is a scanning electron microscope (SEM) photograph of the planar view which shows the result about the time dependence in the 2nd process in the resist residual film removal in a reference example, (a) is the resist pattern after the development process of Example 1 (B) is a time that the thickness of the resist pattern 3 ′ can be cut by 18 nm, (c) is a time that can be cut by 28 nm, and (d) is a time that can be cut by 38 nm. It is a picture of the case. In a reference example, it is a scanning electron microscope (SEM) photograph of the planar view which shows the result about the effect of the 2nd process in resist residual film removal, (a) is after development processing, (b) is 1 step of hitting. (C) is a photograph which shows the mode after forming an uneven | corrugated pattern in a board | substrate after the resist residual film removal which performed the 2nd process without performing. It is a scanning electron microscope (SEM) photograph of the planar view which shows the result about the effect of the 2nd process in resist residual film removal in a reference example, and (a) is when a pattern period in electron beam drawing is 35 nm. It is a photograph in plan view of the resist pattern and the uneven pattern of the substrate, and (b) is a photograph when the pattern period is 30 nm. In (a) and (b), the upper photograph is a photograph of a resist pattern, and the lower photograph is a photograph of an uneven pattern of a substrate.

Hereinafter, modes for carrying out the present invention will be described. In <Embodiment 1>, description will be given in the following order.
1. Mold production method A) Preparation of substrate B) Formation of resist layer C) Pattern exposure D) Development (formation of resist pattern)
E) Resist residual film removal (resist processing method for enlarging the concave diameter of resist pattern)
1) 1st process 2) 2nd process F) Etching to substrate (formation of uneven pattern on substrate)
G) Removal of resist pattern H) Cleaning, etc. Effects of the embodiment

In <Embodiment 1>, a case where a resist layer is provided over a substrate (that is, a case where a hard mask layer is not provided) will be described.
In <Embodiment 2>, a case where a hard mask layer is provided over a substrate and a resist layer is provided thereover will be described.
In <Embodiment 3>, modifications other than those described in the above embodiment will be described.

<Embodiment 1>
(1. Mold manufacturing method)
Hereinafter, the present embodiment will be described with reference to FIG. FIG. 1 is a diagram schematically showing the manufacturing process of the mold 1 in this embodiment. FIG. 1A shows a base body (in this embodiment, a mold substrate 2 (hereinafter also simply referred to as a substrate 2)) on which the mold 1 is based, and FIG. A mode that the layer 3 was formed is shown. FIG. 1C shows a state in which a resist pattern 3 ′ is formed by drawing and developing a predetermined pattern on the resist layer 3. And FIG.1 (d) shows a mode that the resist pattern 3 'performed the 1st process in resist residual film removal (the recessed part 3a width expansion of the resist pattern 3'), and expanded the opening part 4 of the said recessed part 3a, In FIG. 1E, the second step is performed after the first step, and the bottom portion 5 of the concave portion 3a is enlarged to expose a portion having a predetermined width in the substrate 2 to form an exposed portion 6 of the substrate 2. Show the state. FIG. 1 (f) shows a state in which the concave / convex pattern 2 ′ is formed by etching the substrate 2. FIG. 1 (g) is a view showing a state where cleaning is performed after etching, the resist pattern 3 ′ is removed, and the mold 1 is completed.

  The meaning of the “recess 2a having a predetermined width and pattern” formed on the main surface of the substrate refers to the width of the recess 2a as designed when the uneven pattern 2 ′ is formed on the substrate. This means having an uneven arrangement.

A) Preparation of Substrate First, as shown in FIG. 1A, a substrate 2 as a base for the mold 1 is prepared. The “base” in the present embodiment includes the substrate 2 as shown in the present specification, and a substrate in which a hard mask layer is provided on the substrate 2. In summary, it refers to the substance itself that is to be provided with the resist pattern 3 ′ on the main surface.

Further, the substrate 2 in the present embodiment is a master used for manufacturing a magnetic recording medium having a plurality of tracks, or for manufacturing a working mold used for manufacturing a magnetic recording medium having a plurality of tracks by imprinting. It is the board | substrate used as a mold. That is, it is a substrate that becomes an imprint mold for producing a bit patterned medium by an imprint method.
In the present embodiment, description will be made using a substrate 2 made of wafer-shaped quartz.

B) Formation of resist layer Next, a resist chemical solution is applied to the main surface of the substrate 2. As a coating method, in this embodiment, a spin coating method is used in which a resist chemical solution is applied from above the substrate 2 while rotating at a predetermined rotational speed. Thus, after apply | coating a resist chemical | medical solution, the resist layer 3 is formed in the main surface of the board | substrate 2 as shown in FIG.1 (b) by baking.

  In addition, as a kind of resist, a well-known thing may be sufficient and a chemically amplified resist may be sufficient as long as it has reactivity when irradiated with an energy beam. Specifically, it may be a resist that needs to be developed with a developer, and may be a resist having sensitivity to ultraviolet rays, X-rays, electron beams, ion beams, proton beams, and the like. In this embodiment, a case where a positive resist used when pattern exposure by electron beam drawing is performed will be described.

In addition, if the resist layer 3 is made of a positive resist, the solubility in the developer at the place where pattern exposure is performed by drawing with an electron beam, which will be described later, is improved, and the resist is made up of irregularities formed after the development process. It becomes the recess 3a of the pattern 3 '.
On the other hand, as will be described in detail in <Embodiment 3>, if the resist layer 3 is made of a negative resist, the portion subjected to pattern exposure is cured and the solubility in the developer is reduced. As a result, a pattern having a correspondence relationship opposite to the concavo-convex relationship of the positive resist is formed.

  In addition, the thickness of the resist layer 3 at this time is preferably such a thickness that the resist layer 3 remains until etching on the substrate 2 is completed. This is because not only the portion corresponding to the resist dissolution portion formed in the resist layer 3 but also the resist layer 3 in the resist non-dissolution portion is removed by etching on the substrate 2.

  An adhesion layer may be provided between the substrate 2 and the resist layer 3. An example of the adhesive layer is amorphous silicon. Of course, if the resist layer 3 can be satisfactorily adhered to the main surface of the substrate 2, the adhesion layer need not be provided. Further, other layers may be provided as needed.

C) Pattern exposure The pattern exposure in the present embodiment is exposure using the energy beam irradiation described above, and may be any known pattern exposure such as electron beam drawing or lithography. Further, the shape of the pattern is not limited, and may be a line shape, a dot shape (dot pattern), a mixed shape thereof, or the like. As an example, a predetermined fine pattern for manufacturing bit patterned media (BPM) may be drawn on the resist layer 3 using an electron beam drawing machine. This fine pattern may be on the micron order, but it may be on the nano order from the viewpoint of the performance of electronic devices in recent years. Is preferred. Here, “pattern exposure” refers to forming an irradiation region of the resist layer 3 with an energy beam in a predetermined shape in order to form a resist pattern 3 ′ having a predetermined shape.
In this embodiment, when pattern exposure is performed in the form of dots, the case where the recesses 2a provided on the main surface of the substrate 2 and the recesses 3a of the resist pattern 3 ′ are formed in the form of dots is taken as an example.

  In the present embodiment, when the resist layer 3 is irradiated with the electron beam, the diameter of the irradiation region is set to the predetermined diameter (designed diameter in the recess 2 a to be formed on the main surface of the substrate 2). The pattern exposure is performed in the form of dots. This is also a preparation for enlarging the width of the concave portion 3a of the resist pattern 3 'by removing the residual resist film E) described later.

  Here, the “irradiation region” refers to a region where the resist layer 3 is actually irradiated with an energy beam (electron beam). In the above-described problem 1, a portion that is not an irradiation area actually accumulates an exposure amount and becomes an exposure area. As a countermeasure for this, the irradiation area is made smaller in advance when the electron beam is irradiated. By doing so, even if the resist residual film is removed later, the convex portions 3b of the resist pattern 3 ′ can be sufficiently left, and the concave portions 3a of the resist pattern 3 ′ can be prevented from communicating with each other. it can.

D) Development (formation of resist pattern)
By developing the substrate 2 having the drawn resist layer 3, as shown in FIG. 1C, a resist pattern 3 ′ having predetermined unevenness is obtained. This state is also shown in FIG. 3A, which is a schematic cross-sectional view of a substrate with a resist pattern 3 'of an example described later. The development processing in the present embodiment may be a known method.

By this development processing, the exposed portion (resist dissolving portion) in the resist layer 3 is removed, and a resist pattern 3 ′ corresponding to a predetermined fine pattern is formed.
Immediately after stopping the supply of the developer, the rinse agent is supplied dropwise from above the substrate 2 while rotating the substrate 2 in order to wash away the developer. Thereafter, a drying process is performed on the substrate 2 subjected to the rinsing process. In this way, the substrate 2 on which the resist pattern 3 ′ composed of the predetermined resist dissolving portion and the resist non-dissolving portion is formed is obtained.

E) Resist residual film removal (resist processing method for enlarging the concave diameter of resist pattern)
By the above development process, a resist pattern 3 ′ having unevenness can be formed on the main surface of the substrate 2. Ideally, the resist pattern 3 ′ has the substrate 2 exposed in the recess 3a of the resist pattern 3 ′ after the development process. However, there may still be a residual resist film on the substrate 2. This step is performed to remove the remaining film. In this embodiment, the diameter of the concave portion 3a of the resist pattern 3 ′ is increased by removing the resist pattern 3 ′ while also removing the remaining resist film. One of the characteristics of the present embodiment is that this enlargement is performed in the following first and second steps.

1) First step
As the first step, first, the diameter of the opening 4 of the recess 3a in the resist pattern 3 ′ is substantially equal to the predetermined diameter as shown in FIG. 1 (d) and FIG. 3 (b-1). Expand to the same diameter. Here, in the above-described C) pattern exposure, when the resist layer 3 was irradiated with the energy beam, the diameter of the irradiation region was made smaller than the predetermined diameter and the pattern exposure was performed in a dot shape. Comes to life. That is, in the stage immediately after the development processing, the diameter of the concave portion 3a of the resist pattern 3 ′ is intentionally made smaller than the design. Thereafter, in the thickness direction of the resist layer 3 and the extending direction of the resist layer 3, the main surface of the concave portion 3a of the resist pattern 3 ′ is shaved at substantially the same removal rate, and the diameter of the opening 4 of the concave portion 3a is reduced. , And expands to a predetermined diameter (diameter of the recess 2a to be provided on the substrate 2). This is the first step of E) resist residual film removal in this embodiment.

  In the present specification, “the opening 4 of the recess 3a in the resist pattern 3 ′” refers to a hole-like portion that forms the recess 3a on the main surface of the resist pattern 3 ′. Incidentally, “the bottom 5 of the recess 3 a in the resist pattern 3 ′” indicates a portion in the vicinity of the substrate 2 in the recess 3 a of the resist pattern 3 ′. The “diameter of the recess 3 a of the resist pattern 3 ′” refers to the diameter of the entire recess 3 a of the resist pattern 3 ′ in the thickness direction of the resist layer 3. That is, when the expression “diameter of the recess 3a of the resist pattern 3 ′” is used, the opening 4 and the bottom 5 of the recess 3a of the resist pattern 3 ′ have substantially the same diameter. In addition, “substantially” in “expanding the diameter of the opening 4 of the recess 3a in the resist pattern 3 ′ to a diameter substantially the same as a predetermined diameter” is, of course, the same diameter. In some cases, even if they are not the same, this includes a case where the diameter of the opening 4 of the recess 3 a of the resist pattern 3 ′ is different from that of the bottom 5.

  When performing the first step, the diameter of the concave portion 3a of the resist pattern 3 'enlarged in the first step is preferably set to a diameter that does not overlap with the concave portion 3a of the adjacent resist pattern 3'. By doing so, as in the originally set purpose, the adjacent recesses 3a in the resist pattern 3 'are not in communication with each other, and the possibility of causing a pattern defect can be suppressed.

  In FIGS. 1D and 3B-1, only the recess 3a is cut away in order to emphasize the enlargement of the recess 3a of the resist pattern 3 ′. A small amount of the entire main surface of the resist pattern 3 ′ is removed by the process. However, if this removal is abundant, as described above, even a portion that should originally be left as a resist pattern is scraped off and becomes extremely thin or disappears. Therefore, in the first step, it is necessary to limit the time to the extent that the recess 3a of the resist pattern 3 'is expanded to a predetermined width without causing ultrathinning or disappearance.

2) Second Step Next, as a second step, as shown in FIG. 1 (e) and FIG. 3 (b-2), a portion corresponding to the concave portion 3a of the resist pattern 3 ′ is exposed on the base. . In that case, the diameter of the concave portion 3a of the resist pattern 3 ′ is substantially equal to the diameter of the opening 4 by scraping the portion of the main surface of the concave portion 3a in the resist pattern 3 ′ substantially in the thickness direction. Are the same. That is, by shaving the main surface of the recess 3a in the thickness direction of the resist layer 3, the bottom 5 of the recess 3a (and thus the exposed portion 6 in the substrate 2) finally has a predetermined diameter. The second step is performed.

  The phrase “substantially cut in the thickness direction” means that the removal rate in the thickness direction of the resist layer 3 is increased at least as compared with 1) the first step. As a result, the thickness of the resist layer 3 is such that the diameter of the opening 4 of the recess 3a of the resist pattern 3 ′ can be transmitted to the bottom 5 of the recess 3a of the resist pattern 3 ′ and thus to the exposed portion 6 of the substrate 2. This means that the removal rate in the direction is higher than the removal rate in the extending direction of the resist layer 3. At this time, even after the resist residual film is removed so that the bottom 5 of the recess 3a of the resist pattern 3 ′ and thus the exposed portion 6 of the substrate 2 has a predetermined diameter, the opening of the recess 3a of the resist pattern 3 ′ It is preferred that the part 4 remains with a predetermined width.

  Incidentally, “substantially” in “making the diameter of the recess 3 a of the resist pattern 3 ′ substantially the same as the diameter of the opening 4” naturally includes the case where both have the same diameter. Even if they are not the same, when the diameter of the opening 4 is large enough to expose the portion of the substrate 2 where the recess 2a is finally formed (that is, the opening 4 that is substantially the same as the predetermined diameter). In the case where there is a difference in diameter that can be transmitted to the exposed portion 6 in the substrate 2).

  In this embodiment, the resist residual film removal is not performed as a single process, but the resist residual film removal is performed in the first process and the second process. That is, after the diameter of the opening 4 of the recess 3a of the resist pattern 3 ′ is enlarged, the entire recess 3a of the resist pattern 3 ′ is enlarged in accordance with the diameter of the opening 4, and the resist pattern 3 ′ is divided. The entire recess 3a is enlarged. The diameter of the entire recess 3 a of the resist pattern 3 ′ is substantially matched with the diameter of the recess 2 a of the uneven pattern 2 ′ provided on the substrate 2.

  As described above, when irradiating the resist layer 3 with the energy beam, pattern exposure is performed in a dot shape by making the diameter of the irradiation region smaller than the diameter of the concave portion 2a of the concave-convex pattern 2 ′ provided on the substrate 2. The residual resist film is removed through two steps of the first step and the second step.

  First, by reducing the diameter of the irradiation region to be smaller than the predetermined diameter, even if the exposure amount in the convex portion 3b (non-exposed region) of the resist pattern 3 ′ accumulates with the miniaturization of the pattern period, the concave portions 3a The diameter of the convex portion 3b of the resist pattern 3 ′ that should be separated from each other can be secured with a margin, and even if the resist residual film is removed, the convex portion 3b itself of the resist pattern 3 ′ is removed. Can be suppressed. Thus, when the resist residual film is removed, it is possible to suppress communication between adjacent recesses 3a in the resist pattern 3 '. As a result, the above problem 1 can be solved.

  In addition, since the main surface of the recess 3a of the resist pattern 3 ′ is specially cut in the thickness direction of the resist layer 3 in the second step, the bottom 5 of the recess 3a of the resist pattern 3 ′ is formed in the first step. Thus, the opening 4 has the same diameter as that of the opening 4, and the entire recess 3 a of the resist pattern 3 ′ has the same diameter as the opening 4. At the same time, the opening 4 of the recess 3 a of the resist pattern 3 ′ has substantially the same diameter as the recess 2 a of the concavo-convex pattern 2 ′ provided on the substrate 2. Thus, the entire concave portion 3a of the resist pattern 3 ′ has a predetermined concave portion 2a diameter of the concave-convex pattern 2 ′ provided on the substrate 2. Even when viewed in plan, the concave portion 2a diameter as designed is obtained. It can be confirmed that a resist pattern 3 ′ having the same is formed. As a result, the above problem 2 can be solved.

  Further, according to the present embodiment, the adjustment of the diameter of the concave portion 3a of the resist pattern 3 'can be performed while removing the resist residual film. As a result, the number of steps can be reduced, and finally, the yield can be improved and the cost can be reduced.

  Moreover, the method of the present embodiment reduces the size of the recess and the pattern period as long as improvement in resist resolution and miniaturization of pattern exposure itself (for example, miniaturization of the beam diameter of an electron beam lithography system) allow. However, a recess having a predetermined diameter can be formed as designed as a resist pattern 3 ′ (and with respect to the substrate 2) as designed.

  In addition to the above effects, the method of the present embodiment can adjust the shape of the resist pattern 3 ′ so that the shape of the resist pattern 3 ′ has the same diameter at the opening 4 and the bottom 5 of the recess 3a. it can. More specifically, even after the resist layer 3 is developed to form a resist pattern 3 ′ having a predetermined resolution, the resist pattern 3 ′ is improved so that the resolution of the resist pattern 3 ′ is improved. Can be shaped. That is, the bottom of the recess 3a of the resist pattern 3 ′ can be made substantially free from the bottom of the resist, and the boundary between the protrusion 3b and the recess 3a in the resist pattern 3 ′ can be clearly defined. This is possible even after development processing.

  As a specific method of this step, a known method used for removing the residual film of the resist may be used. Specifically, the substrate 2 on which the resist pattern 3 'is formed is introduced into a dry etching apparatus. Then, the residual film of the resist is removed with a mixed gas of oxygen gas and argon (Ar) gas. This residual film of resist is also called scum. Therefore, removal of the remaining resist film is also referred to as descum.

  However, although it has been said that the remaining film removal of the resist may be performed using a known method, the conditions for removing the remaining film are changed in each process in order to distinguish the first process from the second process. There is a need to. More specifically, in the first step, the condition that the recess 3a of the resist pattern 3 'can be cut isotropically, and in the second step, the recess 3a of the resist pattern 3' is specifically cut in the thickness direction. Set conditions that can.

When a mixed gas of oxygen gas and argon gas is used as described above, the overall pressure is 5.0 Pa or less in the first step, and a more preferable example that can be confirmed at the present time is 2.5 Pa or more and 5.0 Pa or less. And In the second step, the total pressure is less than 2.5 Pa, and a more preferable example that can be confirmed at present is 0.68 Pa or more and less than 2.5 Pa. The reason why the above range is preferable is as shown in Reference Examples in the examples described later. The reason why the above range is preferable is that in the case of the second step, Ar or O _{2 is} reduced by reducing the overall pressure. It is presumed that the mean free process can be lengthened and isotropic resist residual film removal can be suppressed. Details are under intensive investigation by the present inventors.

If the pressure is fixed at 0.68 Pa, the flow rate ratio (Ar / O ₂ ) is in the range of 2 to 5 in the first step. In the second step, when the pressure is fixed at 0.68 Pa, the flow rate ratio (Ar / O ₂ ) exceeds 5; as a more preferable example confirmed at the present time, the range is 23 or more. . The reason why the above range is preferable is as shown in the reference examples in the examples to be described later. However, the reason why the above range is preferable is that in the case of the second step, it becomes a cause of isotropic resist residual film removal. It is presumed that isotropic resist residual film removal can be suppressed by making the flow rate of O ₂ smaller than that of Ar. Details are under intensive investigation by the present inventors.

F) Etching to substrate (formation of uneven pattern on substrate)
After the development step, a bit pattern composed of dot-like recesses 2a is formed on the main surface of the substrate 2 by etching. Hereinafter, this etching process will be described.

  In the etching process in the present embodiment, etching using a fluorine-based gas is performed on the substrate 2. Thus, as shown in FIG. 1 (f), the substrate 2 is subjected to uneven processing corresponding to the resist pattern 3 '.

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 as an additive gas) is used. , Ar, Xe, etc.).

The predetermined concavo-convex pattern 2 ′ (fine pattern) may be a pattern in the range from nano-order to micro-order, but is more preferably a nano-order periodic structure of several nanometers to several tens of nanometers. If a specific example is given, it is a fine protrusion structure consisting of a plurality of fine irregularities. Examples of the cross-sectional shape include a triangle, a trapezoid, and a square in the case of a one-dimensional periodic structure. In the case of a two-dimensional periodic structure, the shape of the fine protrusions is not limited to an accurate cone (bus line is straight) or pyramid (ridge line is straight), as long as it is tapered in consideration of extraction after imprinting. The ridgeline shape may be a curved surface with a side surface bulging outward. Specific examples include a bell, a cone, a truncated cone, and a cylinder.
Furthermore, the tip portion may be flattened or rounded in consideration of moldability and breakage resistance. Further, this fine protrusion may be a continuous fine protrusion in one direction.

G) Removal of resist pattern Subsequently, the resist pattern 3 'generated after the third etching is removed by a resist stripper composed of a mixed solution of sulfuric acid and hydrogen peroxide solution to completely remove the resist pattern 3'. Peel off.
Specifically, the substrate 2 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). Subsequently, the board | substrate 2 is dried with the method similar to the said drying process.
The resist remover used here may be a compound that can be removed by swelling and dissolution or chemical decomposition of the resist.

H) Cleaning, etc. After the above steps, the substrate 2 is cleaned if necessary. In this way, as shown in FIG. 1G, the concave / convex pattern 2 ′ is formed on the main surface of the substrate 2 to complete the mold 1.

(2. Effects of the embodiment)
As described above, the mold according to this embodiment is configured. According to the embodiment, the following effects can be obtained.

(Effect based on Knowledge 1)
First, by making the diameter of the irradiated area smaller than the predetermined diameter, even if the exposure amount at the convex part (non-exposed area) of the resist pattern accumulates with the miniaturization of the pattern period, the concave part should be separated. The diameter of the convex portion of the resist pattern can be secured with a margin, and even if the resist residual film is removed, the removal of the convex portion of the resist pattern itself can be suppressed. Thus, when the resist residual film is removed, it is possible to suppress communication between adjacent recesses in the resist pattern.

(Effect based on Knowledge 2)
In addition, E) Resist residual film removal 2) In the second step, the main surface of the concave portion of the resist pattern is sharpened in the thickness direction of the resist layer. The diameter of the opening enlarged in the process is the same, and as a result, the entire recess of the resist pattern has the same diameter as the opening. In this second step, the main surface of the concave portion of the resist pattern is sharpened by specializing in the thickness direction of the resist layer, so the opening portion of the concave portion of the resist pattern is substantially the same as the concave portion of the concave and convex pattern provided on the substrate. Have the same diameter. Thus, the entire recess of the resist pattern has a predetermined recess diameter of the uneven pattern provided on the substrate, and the resist pattern having the designed recess diameter is formed even when viewed in plan. I can confirm that. As a result, a fine uneven pattern as designed can be formed on the substrate.

  From the above results, it is possible to provide a mold manufacturing method and a resist processing method in which a concave portion having a predetermined diameter is formed as designed even if the concavo-convex pattern provided on the main surface is fine.

<Embodiment 2>
In the first embodiment, the case where the hard mask layer is not provided has been described. In this embodiment, a case where a hard mask layer is provided between the substrate 2 and the resist layer 3 will be described.

(Type of hard mask layer)
As the hard mask layer, a known one may be used. Specific examples include a chromium nitride (CrN) layer. Further, other than chromium nitride, for example, a chromium compound (containing N, C and O, or any one or a combination thereof), a molybdenum compound, SiC, amorphous carbon, or Al may be used.

  Note that a conductive layer may be separately formed in addition to the chromium nitride layer. The conductive layer may be a known layer. As an example, a compound containing Ta as a main component as described above may be used. In addition, a compound containing Hf or Zr may be used. Moreover, you may use said chromium nitride layer as an antioxidant layer of the said conductive layer.

  Note that the “hard mask layer” in the present embodiment is composed of a single layer or a plurality of layers, and can protect a portion where unevenness corresponding to the pattern is to be formed, and the uneven pattern 2 ′ on the substrate 2 can be protected. The “hard mask” means that a pattern having a shape corresponding to the concavo-convex pattern 2 ′ is formed on the hard mask layer.

(Etching to hard mask layer)
The hard mask layer is etched in the presence of the resist pattern 3 ′ to form a mask pattern 8 ′. Note that this etching method may be determined according to the material of the hard mask layer, and dry etching, wet etching, or the like may be used according to the type of the hard mask layer. In addition, etching is performed on the adhesion layer as necessary.

  A known method may be used as this etching method. To give a specific example, the substrate 2 having a resist pattern 3 'formed on the substrate 2 is introduced into a dry etching apparatus. When a chromium nitride layer is provided as a hard mask layer as in this embodiment, dry etching is substantially performed with oxygen and chlorine gas. By this etching, an uneven pattern is formed on the hard mask layer using the resist pattern 3 ′ as a mask, and the hard mask is formed on the main surface of the substrate 2.

(Removing the hard mask)
After etching the substrate 2 to form the concave / convex pattern 2 ′ on the main surface of the substrate 2, the hard mask is removed. The removal of the hard mask may be appropriately selected according to the material of the hard mask layer. Note that after removing the resist pattern 3 ′, the hard mask may be removed by using the same technique as the etching for the hard mask layer.

  In this embodiment, dry etching is performed. However, dry or wet etching may be additionally performed depending on the material constituting the hard mask layer other than the conductive layer and the antioxidant layer.

<Embodiment 3>
Hereinafter, modifications other than the above-described embodiment will be described.

(Resist pattern recess shape)
In the first embodiment, the case where the dot-shaped recess 2a is formed on the substrate 2 on the premise of the production of BPM has been described. However, as already described in the first embodiment, the shape of the pattern is not limited, The shape may be a line shape, a dot shape (dot pattern), a mixture thereof, or the like. If the recess 2a is linear, the idea of the present invention can be achieved by setting the “diameter” to “width” in the description of “predetermined diameter”, “diameter of the recess”, “diameter of the opening”, and the like in the first embodiment. The present invention can also be applied when the recess 2a is linear. In addition, the expression “width” in this specification is an expression including “diameter”.

(Bottom of the recess in the resist pattern)
In the first embodiment, the case where the remaining film in the recess 3a of the resist pattern 3 ′ is removed in 2) the second step in E) resist remaining film removal has been described. On the other hand, the remaining film is not removed in the second step, and the shape of the resist pattern 3 ′ is changed while leaving the bottom portion 5 of the recess 3a of the resist pattern 3 ′ (that is, in the state where the exposed portion 6 is not formed in the substrate 2). In order to prepare, the first step and the second step may be performed. That is, instead of removing the residual film in the second step, the first step and the second step may be performed in order to increase the resolution of the resist pattern 3 ′. As described above, according to the method of the present embodiment, it is possible to clarify the boundary between the concave portion 3a and the convex portion 3b in the resist pattern 3 ′ even after the development processing. Therefore, as a step different from the resist residual film removal, a step of increasing the resolution of the resist pattern 3 ′ may be performed.

(Negative resist)
In the first embodiment, an example using a positive resist has been described. However, the idea of the present invention can be applied even when a negative resist is used. When a negative resist is used, the portion irradiated with the energy beam becomes the resist non-dissolved portion, and becomes the convex portion 3b in the resist pattern 3 ′. For this reason, C) it is necessary to perform the opposite of the first embodiment at the time of pattern exposure. That is, when the resist layer 3 is irradiated with the energy beam, the diameter of the irradiation region is “larger” than the predetermined width (designed width of the concave portion 2 a to be formed on the main surface of the substrate 2). Then, pattern exposure is performed. By doing so, the diameter of the convex portion 3b of the resist pattern 3 ′ that should separate the concave portions 3a can be secured with a margin, and even if the resist residual film is removed, the convexity of the resist pattern 3 ′ can be secured. It can suppress that the part 3b itself is removed. Thus, when the resist residual film is removed, it is possible to prevent the adjacent recesses 3a from communicating with each other in the resist pattern 3 ′. As a result, the above problem 1 can be solved even in the case of a negative resist. When using a negative resist, contrary to the first embodiment, the exposure amount accumulates in the concave portion 3a of the resist pattern 3 ′ as the pattern period becomes finer. The concave portion 3a of the resist pattern 3 ′ is a resist dissolving portion. Therefore, when the above method is used, the width of the recess 3a of the resist pattern 3 ′ is smaller than the design. At that time, the above-described method (enlargement of the width of the concave portion 3a of the resist pattern 3 ') is performed in two stages, thereby setting the width of the concave portion 3a of the resist pattern 3' to a predetermined width. The part which has the width | variety of this can be exposed, and said subject 2 can also be solved. As a result, even when a negative resist is used, the object of the present invention can be sufficiently achieved.

(Resist pattern preparation process)
In the first embodiment, A) preparation of the substrate to D) development has been described, but E) a person who removes the resist residual film does not actually perform these steps, but has already performed resist. Needless to say, the present invention can also be applied to the case where the substrate on which the pattern 3 'is formed is prepared, and E) resist residual film is removed from the substrate. That is, A) preparation of the substrate to D) development are collectively formed into a resist pattern 3 ′ having unevenness formed on the main surface of the substrate, and the width of the opening 4 of the recess 3 a is smaller than a predetermined width. Alternatively, a resist pattern preparation process for preparing the resist pattern 3 ′ may be used.
Note that the “predetermined width” in this case may be the designed width of the concave portion 2a of the concave / convex pattern 2 ′ to be formed on the substrate 2 as described in the first embodiment. The width of the recess 3a that the resist pattern 3 ′ should finally have is set to “predetermined width”, and a resist pattern having a recess width smaller than the predetermined width is prepared in the resist pattern preparation step. Then, the recess may be enlarged with the aim of this width.

(Steps other than the first step and the second step)
Moreover, E) The resist residual film removal may not be performed in the first step and the second step, but another step may be provided. As a specific example, the first step and the second step may be performed on the resist pattern 3 ′ a plurality of times, with the first step and the second step as a set of steps. Moreover, you may provide the process of adjusting the thickness of resist pattern 3 'separately.

(Copy mold)
In the first embodiment, a method for producing a master mold has been described as an example. However, the idea of the present invention can also be applied to a case where a copy mold is produced using a master mold as an original mold. More specifically, a resist layer 3 is formed on the main surface of a base for copy mold, the master mold is pressed against the resist layer 3, and the concave / convex pattern 2 ′ of the master mold is applied to the resist layer 3. Transcript. When optical imprinting is used, the resist layer 3 is exposed in this state to form a resist pattern 3 ′. Thereafter, the resist residual film in the recess 3a of the resist pattern 3 ′ is removed, and the above-described method can be applied at that time. When pressing the master mold, a release layer may be provided on the master mold as needed.
In this specification, the master mold and the copy mold are simply referred to as “mold”. At this time, the concept of the present invention is applied regardless of whether the method for producing the copy mold is optical imprint using a photocurable resin as a resist or thermal imprint using a thermoplastic resin as a resist. Is possible.

  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.

<Example 1>
Next, Example 1 will be shown to specifically explain the present invention.
In this example, a disc-shaped synthetic quartz substrate (outer diameter 150 mm, thickness 0.7 mm) was used as the substrate 2 (FIG. 1A). On this substrate 2, a resist chemical solution for electron beam drawing (ZEP520A manufactured by Nippon Zeon Co., Ltd.) was applied by spin coating to a thickness of 45 nm and baked to form a resist layer 3 on the main surface of the substrate 2 (FIG. 1 (b)).

  Next, after drawing a pattern having a dot-like periodic structure on the resist layer 3 using an electron beam drawing machine (pressurized voltage 100 kV), development processing was performed to form a resist pattern 3 ′ (FIG. 1C). )). The pattern period was 35 nm. The diameter of the recess formed after development was 11.08 nm.

Then, the residual resist film was removed in two stages for this resist pattern 3 ′ (FIGS. 1D and 1E). As specific conditions, first, a mixed gas of oxygen gas and argon gas was used. In the first step, the total pressure is 2.5 Pa, and the flow rate ratio (Ar / O ₂ ) is 5 (= 100 sccm / 20 sccm). In the second step, the total pressure is 0.68 Pa, and the flow rate ratio (Ar / O ₂ ) is 23 (= 115 sccm / 5 sccm). In the first and second steps, the bias was 20 W, and the ambient temperature when removing the resist residual film was 20 ° C. The residual resist film was removed in a time that the thickness of the resist pattern 3 ′ was cut by 28 nm. Further, the amount of decrease in the thickness of the resist pattern 3 ′ was converted into time from the previously measured resist etching rate. In addition, the etching rate used the optical film thickness measuring device.

Subsequently, dry etching (CHF ₃ : Ar = 1: 9 (volume ratio)) using a fluorine-based gas was performed on the substrate 2 in a dry etching apparatus using the resist pattern 3 ′ as a mask. In this way, dot-shaped recesses (holes) 2a corresponding to the fine pattern were formed on the substrate 2 (FIG. 1 (f)).

  Then, the resist pattern 3 ′ was removed using sulfuric acid / hydrogen peroxide (concentrated sulfuric acid: hydrogen peroxide solution = 2: 1 (volume ratio)) composed of concentrated sulfuric acid and hydrogen peroxide solution.

  The mold 1 in the present example was manufactured by performing the above steps and appropriately washing and drying. (FIG. 1 (g)).

<Example 2>
In Example 1, the pattern period was 35 nm, and the diameter of the recess formed after development was 11.08 nm. On the other hand, in Example 2, the pattern period was 30 nm, and the diameter of the recess formed after development was 11.30 nm.

<Comparative Example 1>
In Example 1, the residual resist film was removed in two stages. In Comparative Example 1, the residual resist film was removed in one stage. The conditions were the same as in the first step of Example 1. Otherwise, the mold was produced in the same manner as in Example 1.

<Evaluation>
About the mold obtained by Examples 1-2 and the comparative example 1, it observed using the scanning electron microscope (SEM) (magnification 200,000 times).

  As a result, in Example 1, the concave portion having substantially the same diameter as that at the stage where the resist pattern 3 ′ was formed (upper side in FIG. 2A) was also formed as the concave / convex pattern 2 ′ on the substrate 2 ( FIG. 2 (a) lower side). This is presumably because the recess 3a of the resist pattern 3 'had the diameter of the recess 2a to be formed on the substrate 2 even at the stage where the resist residual film was removed.

  Also, in Example 2, the concave portion having substantially the same diameter as that at the stage of forming the resist pattern 3 ′ (upper side in FIG. 2B) was also formed as the concave / convex pattern 2 ′ in the substrate 2 (FIG. 2). 2 (b) lower side). This is considered to be because the concave portion 3a of the resist pattern 3 'had a diameter almost the same as the concave portion 2a to be formed on the substrate 2 even at the stage where the resist residual film was removed. .

Further, from the viewpoint of increasing the width of the recess, when viewing FIG. 2A, the width of the recess 3a of the resist pattern 3 ′ is 11.08 nm, and the width of the recess 2a of the uneven pattern 2 ′ on the substrate 2 Was 15.90 nm, and it was found that 4.82 nm could be enlarged from the recess 3a to the recess 2a.
2B, the width of the recess 3a of the resist pattern 3 ′ is 11.30 nm, the width of the recess 2a of the uneven pattern 2 ′ on the substrate 2 is 16.90 nm, and the recess 3a → It was found that 5.60 nm could be expanded into the recess 2a.
2A and 2B, according to the method of the first embodiment, the pattern period of the concave / convex pattern 2 ′ actually formed on the substrate 2 as well as the resist pattern 3 ′ is 35 nm and 30 nm. Even if the pattern size is fine, the resist pattern 3 ′ can be formed even if the width of the recess 3 a of the resist pattern 3 ′ is further smaller than the width of the recess 2 a of the concavo-convex pattern 2 ′ on the substrate 2. It was found that the concavo-convex pattern 2 ′ on the substrate 2 can be obtained normally by enlarging the width of the recess 3a by removing the residual resist film.

  On the other hand, in Comparative Example 1, the concave portion 3a having the designed diameter was formed at the stage where the resist pattern 3 ′ was formed (FIG. 4A), but the resist pattern 3 ′ after removal of the resist residual film was planarized. When observed visually, the concave portion 3a of the resist pattern 3 ′ having a diameter larger than a predetermined diameter was formed (FIG. 4B). Furthermore, when the concave / convex pattern 2 ′ is formed on the main surface of the substrate 2 in this state, a concave portion 2 a having a diameter smaller than a predetermined diameter is formed (FIG. 4C).

<Reference example>
In addition to Example 1 and Comparative Example 1, the present invention is further investigated in order to verify the dependency of the first step and the second step on the pressure / flow rate ratio / time and the effect of the second step alone in removing the resist residual film. A resist pattern 3 ′ was prepared as a reference example shown in detail.

(Pressure dependence)
FIG. 6A is a photograph of the same resist pattern 3 ′ as in Example 1. Resist residual film removal was performed on this resist pattern 3 ′ at a flow rate ratio (Ar / O ₂ ) of 5 (= 100 sccm / 20 sccm), a bias of 20 W, and an atmospheric temperature during resist residual film removal of 20 ° C. .

  At that time, the result when the pressure of the entire atmosphere is 2.5 Pa is FIG. 6B, the result when 5.0 Pa is set is FIG. 6C, and the result when 0.68 Pa is set is FIG. d). When this is seen, about FIG.6 (b) (c), the recessed part width | variety can be expanded compared with Fig.6 (a). Therefore, it was found that the pressure of the entire atmosphere in the first step is preferably 5.0 Pa or less, and more preferably 2.5 Pa or more and 5.0 Pa or less. On the other hand, in FIG. 6A, since the expansion of the recess width can be suppressed, the pressure of the entire atmosphere in the second step is preferably less than 2.5 Pa, and more preferably 0.68 Pa to less than 2.5 Pa. I understood it.

(Flow ratio dependency)
Further, when the whole pressure is fixed at 0.68 Pa, the result when the flow rate ratio (Ar / O ₂ ) is 5 (= 100 sccm / 20 sccm) and O ₂ is 16.7 vol% is shown in FIG. FIG. 7B shows the results when the flow rate ratio (Ar / O ₂ ) is 2 (= 80 sccm / 40 sccm) and O ₂ is 33.3 vol%, and the overall pressure is 2.5 Pa. The result of perspectiveing the pattern 3 ′ is FIG. 7 (c). FIG. 7 (d) shows the result when the flow rate ratio (Ar / O ₂ ) is 2 (= 115 sccm / 5 sccm) and 4.2% by volume of O ₂ , and FIG. It is. Note that the bias is 20 W, and the ambient temperature when removing the resist residual film is 20 ° C.

7A to 7E, the recess width can be enlarged in FIGS. 7A and 7B. Therefore, it was found that the flow rate ratio (Ar / O ₂ ) in the first step is preferably 2 or more and 5 or less when the pressure is fixed at 0.68 Pa. On the other hand, in FIG. 7D, since the expansion of the recess width can be suppressed, when the pressure is fixed at 0.68 Pa, the flow rate ratio (Ar / O ₂ ) is a value exceeding 5, In other words, it was found that it is preferably 23 or more. Further, FIG. 7 (c) in which the resist pattern 3 ′ was produced under conditions suitable for the first process was compared with FIG. 7 (e) in which the resist pattern 3 ′ was produced under conditions suitable for the second process. In the case shown in FIG. 7 (e), the convex portions of the resist pattern 3 ′ could be appropriately left.

(Time dependency)
The time dependency was examined for each of the conditions of the first step and the conditions of the second step of Example 1. In addition, since the thickness of the resist to be removed increases as the resist residual film removal time becomes longer, the shape change of the resist pattern 3 ′ according to the thickness of the removed resist is regarded as “time dependency”. .

  The results of examining the time dependency of the first step of Example 1 are FIGS. 8A to 8D, and the results of examining the time dependency of the second step are FIGS. 9A to 9D. is there. In each figure, (a) is a photograph of the resist pattern 3 ′ before the residual resist film is removed, (b) is a time that the thickness of the resist pattern 3 ′ can be cut by 18 nm, and (c) is cut by 28 nm. (D) is a photograph in the case where the resist residual film is removed in a time enough to scrape 38 nm. Looking at this, in the case of the first step (FIG. 8), the width of the opening 4 of the recess 3a in the resist pattern 3 'is increased by extending the resist remaining film removal time. On the other hand, in the case of the second step (FIG. 9), the width of the opening 4 of the recess 3a in the resist pattern 3 'is hardly enlarged even if the resist residual film removal time is lengthened. From this, it was found that the main surface portion of the recess 3a in the resist pattern 3 'can be removed in the thickness direction.

(Verification of the effect of the second step)
When verifying the effect of the second step, the results when the first step is not performed in Example 1 are shown in FIGS. Here, (a) is a photograph of the resist pattern 3 ′ before the resist residual film is removed, and (b) is a case where the resist residual film is removed in a time enough to reduce the thickness of the resist pattern 3 ′ by 28 nm. It is a photograph, and (c) is a photograph of the concave-convex pattern 2 ′ of the substrate 2. It can be seen that even after the second step, the diameter of the concave portion of the resist pattern 3 ′ is almost the same, and even if the concave and convex pattern 2 ′ is formed on the substrate 2, the diameter of the same size can be maintained. did it.

  Further, in verifying the effect of the second step, it is necessary to show that the uneven pattern 2 ′ on the substrate 2 can be normally obtained even if the pattern period is as small as 30 nm to 35 nm instead of the pattern period of 60 nm as described above. The mold in which the resist pattern 3 ′ and the concave / convex pattern 2 ′ were formed on the substrate was produced by changing the pattern period in electron beam drawing (35 nm, 30 nm). In addition, about the manufacturing method of a mold, it is the same as that of the method of Example 1 except not having performed the 1st process. The result of observing the mold with a scanning electron microscope is shown in FIG. FIG. 11A is a photograph in plan view of the resist pattern 3 ′ and the uneven pattern 2 ′ of the substrate 2 when the pattern period is 35 nm, and FIG. 11B is a photograph when the pattern period is 30 nm. is there. 11A and 11B, the upper photograph is a photograph of the resist pattern 3 ', and the lower photograph is a photograph of the concave-convex pattern 2' of the substrate 2.

  As shown in FIG. 11, when the second step is adopted, not only the resist pattern 3 ′ but also the concave / convex pattern 2 ′ actually formed on the substrate 2 has a fine pattern size with a pattern period of 35 nm and 30 nm. Even so, it was found to be obtained normally.

DESCRIPTION OF SYMBOLS 1 Mold 2 Substrate 2 'Concave and convex pattern 2a Concave part 3 (of concave / convex pattern formed on substrate) Resist layer 3' Resist pattern 3a Concave part 3b (of resist pattern) Convex part 4 (of resist pattern) Opening part 5 Bottom part 6 Exposed part

Claims (8)

In a method of manufacturing a mold for forming a recess having a predetermined width and pattern on the main surface of a substrate,
A resist layer forming step of forming a resist layer on the substrate;
A pattern exposure step of performing pattern exposure by irradiating the resist layer with an energy beam;
Developing the resist layer that has been subjected to pattern exposure, and forming a resist pattern comprising irregularities; and a resist pattern forming step,
A resist pattern recess width expanding step of expanding the width of the recess of the resist pattern by scraping the resist pattern;
Have
In the pattern exposure step, pattern exposure is performed so that the width of the concave portion of the resist pattern is smaller than the predetermined width,
The resist pattern recess width expanding step,
A first step of expanding the width of the opening of the recess in the resist pattern to a width substantially the same as the predetermined width;
A second step of making the width of the concave portion of the resist pattern substantially the same as the width of the opening by scraping a portion of the main surface of the concave portion in the resist pattern substantially in the thickness direction;
The manufacturing method of the mold characterized by having. The resist layer is a positive resist,
2. The mold manufacturing method according to claim 1, wherein, in the pattern exposure step, a width of an energy beam irradiation region on the resist layer is made smaller than the predetermined width.   The second step is a step of exposing a portion of the substrate corresponding to the concave portion of the resist pattern, and the width of the portion is set to be substantially the same as the predetermined width. The method for producing a mold according to claim 1 or 2.   4. The method of manufacturing a mold according to claim 1, wherein the width of the concave portion of the resist pattern enlarged by the first step is a width that does not overlap with the concave portion of the adjacent resist pattern. .   The method for producing a mold according to any one of claims 1 to 4, wherein the concave portions provided on the main surface of the substrate and the concave portions of the resist pattern are in the form of dots. In a mold manufacturing method for forming dot-shaped recesses having a predetermined diameter and pattern on the main surface of a substrate,
A resist layer forming step of forming a resist layer which is a positive resist on the substrate;
When irradiating the resist layer with an energy beam, a pattern exposure step of performing pattern exposure in a dot shape by making the diameter of the irradiation region smaller than the predetermined diameter; and
Developing the resist layer that has been subjected to pattern exposure, and forming a resist pattern comprising irregularities; and a resist pattern forming step,
A resist residual film removing step of removing the resist residual film on the portion corresponding to the dot-shaped concave portion of the resist pattern in the substrate;
Have
The resist residual film removing step includes
The diameter of the opening of the dot-shaped recess in the resist pattern is a diameter that does not overlap with the dot-shaped recess of the adjacent resist pattern, and expands to a diameter that is substantially the same as the predetermined diameter. 1 process,
By shaving the portion of the main surface of the dot-shaped recess in the resist pattern substantially in the thickness direction, the portion corresponding to the dot-shaped recess of the resist pattern is exposed in the base, A second step in which the diameter of the portion is substantially the same as the diameter of the opening and the predetermined diameter;
The manufacturing method of the mold characterized by having. In the method of manufacturing a mold for processing a resist pattern composed of unevenness to form an uneven pattern on the main surface of the substrate,
A resist pattern comprising a concavo-convex formed on the main surface of the substrate, and a resist pattern preparation step of preparing a resist pattern in which the width of the opening of the concave portion is smaller than a predetermined width;
A resist pattern recess width expanding step of expanding the width of the recess of the resist pattern by scraping the resist pattern;
Have
The recess width expanding step includes:
A first step of expanding the width of the opening of the recess in the resist pattern to a width substantially the same as the predetermined width;
A second step of making the width of the concave portion of the resist pattern substantially the same as the width of the opening by scraping a portion of the main surface of the concave portion in the resist pattern substantially in the thickness direction;
The manufacturing method of the mold characterized by having. In a resist processing method for processing a resist pattern consisting of irregularities,
A resist pattern recess width expanding step of increasing the width of the recess of the resist pattern by scraping a resist pattern formed with a width of the opening of the recess in the resist pattern smaller than a predetermined width;
The recess width expanding step includes:
A first step of expanding the width of the opening of the recess in the resist pattern to a width substantially the same as the predetermined width;
A second step of making the width of the concave portion of the resist pattern substantially the same as the width of the opening by scraping a portion of the main surface of the concave portion in the resist pattern substantially in the thickness direction;
A resist processing method characterized by comprising: