JP2014216365A - Method for manufacturing nanoimprint lithography mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a nanoimprint lithography mask capable of suppressing deterioration of transfer characteristics due to excessive etching around a defect and accumulation of a correction film.SOLUTION: A method for manufacturing an NIL mask having an uneven pattern on a surface of a substrate comprises a protective film forming step, a defect correcting step, and a protective film removing step. The protective film forming step forms a protective film in a region larger than a defect region in which a defect part of the NIL mask exists. The defect correcting step further includes the steps of: observing the defect part; exposing the defect part by partly removing the protective film in the defect region (removal step); and etching the exposed defect part by irradiating it with a charged beam while supplying an assist gas to the defect part or accumulating the correction film by irradiating the defect part with a charged beam while supplying a deposition gas to the defect part (correcting step). The protective film removing step removes a remaining protective film.

Description

  The present invention relates to defect correction of a mask for nanoimprint lithography.

  Nanoimprint lithography is a method of transferring a pattern onto the surface of a transferred object by bringing a nanoimprint template having a desired pattern on the surface into close contact with the curable resin of the transferred object and applying an external stimulus such as heat or light. It is. Nanoimprint lithography can form a pattern by a simple method, and has recently been shown to be capable of transferring ultrafine patterns of several tens to several nanometers. Therefore, nanoimprint lithography is expected as a candidate for next-generation lithography technology.

  Among nanoimprint lithographys, optical nanoimprint lithography has advantages such as high throughput, no dimensional change due to temperature, and easy alignment of nanoimprint templates compared to thermal nanoimprint lithography. Therefore, in recent years, a template for optical nanoimprint lithography has been developed. Hereinafter, a template for nanoimprint lithography may be referred to as a NIL mask.

  As in conventional photomasks, NIL mask defects include those in which unnecessary surplus patterns and foreign substances are present (black defects), and defects that are originally necessary or missing (white defects). There is. In the case of a black defect, a normal pattern can be obtained by removing excess portions and foreign matters. As a black defect correcting method, a method of etching by irradiating a charged beam such as an electron beam or an ion beam while blowing an assist gas is known. In the case of a white defect, a normal pattern can be obtained by depositing a correction film on the missing or missing portion. As a method for correcting white defects, a method of depositing a correction film by irradiating a charged beam while blowing a deposition gas is known (see, for example, Patent Document 1).

  Since assist gas is used to correct black defects and deposition gas is used to correct white defects, after the defect correction, the assist gas or deposition gas is attached to the surface of the NIL mask. It has become. Normally, the assist gas and the deposition gas are exhausted after the defect correction, but it is difficult to exhaust all of the assist gas or deposition gas adhering to the surface of the NIL mask. Therefore, when a charged beam such as an electron beam or an ion beam is irradiated during inspection after defect correction, the surface of the NIL mask is further etched because the assist gas or deposition gas is slightly attached. Or a correction film is deposited. This etching or deposition of the correction film extends to the normal pattern as well as the defect. As a result, the dimension and shape of the pattern change.

  In addition, when the defect is corrected, the charged beam irradiation area is limited to the area where the defect exists in order to prevent etching to a normal pattern or depositing a correction film. However, since the charged beam has a certain extent, there is a possibility that not only the defect portion but also a normal pattern around the defect is etched or a correction film is deposited. Thereby, the dimension and shape of a pattern change like the above-mentioned case.

  In the NIL mask, changes in pattern size and shape greatly affect the transfer characteristics. In particular, in the NIL mask, the concavo-convex pattern of the NIL mask is transferred by being pressed against the transfer target. Therefore, if the size or shape of the concavo-convex pattern of the NIL mask changes, it is transferred to the transfer target as it is, and the A pattern is formed. In reduced exposure using a photomask, since a tetraploid pattern is usually reduced to 1/4, a slight etching or correction film deposition does not resolve and transfer to a transfer target. On the other hand, the NIL mask has a peculiar problem that even a slight etching or deposition of a correction film is transferred to a transfer target because a haploid pattern is transferred in full size. Therefore, the NIL mask requires a particularly high accuracy.

  Here, Patent Document 2 is not a technique related to defect correction of a mask for NIL, but is not a technique for reducing damage to a pattern around a defect, but drift by scanning of a charged beam when performing drift correction in a photomask. In order to suppress damage to the pattern around the correction mark, a method has been proposed in which a protective film is formed on the photomask and a through-hole penetrating only the protective film is provided as a drift correction mark.

JP 2004-294613 A Japanese Patent No. 3041174

In Patent Document 2, in a photomask in which a light-shielding film is formed in a pattern on a glass substrate, when correcting a defective portion, the number of times a charged beam is scanned by drift correction on the light-shielding film near the defective portion. After the protective film having a through-hole (drift correction mark) is formed so that the base of the protective film is not exposed even if the amount of increase is increased, a correction film is deposited on the light shielding film of the defective part to correct the defective part. It is disclosed.
However, this method does not sufficiently protect the substrate surface, and when the above method is applied to the NIL mask, as described above, further etching is performed on the surface of the NIL mask around the defect due to the spread of the charged beam or the like. Or there is a risk of the deposition of a correction film. Further, as described above, the assist gas or deposition gas adheres to the periphery of the defect portion, so that when the defect portion after correction is observed with an electron microscope such as SEM, excessive etching or There is also a risk of correction film deposition. Since the NIL mask is brought into close contact with the transferred object and the uneven pattern is transferred, the defective portion after correction and the minute damage around the transferred portion are also transferred to the transferred object as they are, and the pattern shape and dimensions are changed. .

  The present invention has been made in view of the above problems, and provides a method for manufacturing an NIL mask capable of suppressing deterioration of transfer characteristics due to excessive etching around a defect and deposition of a correction film. Main purpose.

  In order to solve the above problems, the present invention provides a method for manufacturing an NIL mask having a concavo-convex pattern on a main surface of a substrate, wherein a protective film is formed in a region larger than a defect region where a defect portion of the NIL mask exists. A protective film forming step for forming the defect portion, an observation step for observing the defective portion, a removal step for partially removing the protective film in the defective region to expose the defective portion, and the exposed defective portion, Defect repairing step having a repairing step of depositing a correction film by irradiating a charged beam while supplying an assist gas or irradiating a charged beam while supplying a deposition gas, and the remaining protective film And a protective film removing step of removing the NIL mask.

  According to the present invention, in the case of a black defect portion, by forming a protective film, the periphery of the defective portion can be protected by the protective film, and excessive etching around the defective portion is suppressed during the correction process. Can do. In the case of a white defect portion, even if a correction film is deposited on the protective film around the defective portion during the correction process by forming a protective film, the protective film is removed together with the protective film in the protective film removal process. The correction film can be removed. Therefore, it is possible to obtain an NIL mask having excellent transfer characteristics.

  In the above invention, it is preferable that the defect correction step further includes a correction confirmation step of confirming the defect portion after the correction by irradiating a charged beam after the correction step. In the case of a black defect portion, excessive etching can be suppressed not only during the correction process but also during the correction confirmation process by forming a protective film. In the case of a white defect portion, even if a correction film is deposited on the protective film not only during the correction process but also during the correction confirmation process, the correction film on the protective film is removed together with the protective film in the protective film removal process. Can be removed. Therefore, it is possible to obtain a highly accurate NIL mask.

  In the present invention, it is preferable that the NIL mask is light transmissive, the substrate is a light transmissive substrate, and the protective film is a metal film. This is because the metal film has a good etching selectivity with the substrate, and it is easy to remove only the protective film in the protective film removal step.

  Furthermore, in the present invention, the method for removing the protective film in the protective film removing step is preferably wet etching or dry etching.

  In addition, the manufacturing method of the NIL mask of the present invention includes a drift correction mark for forming a drift correction mark on the protective film in a region other than the defect region after the protective film forming step and before the defect correcting step. It is preferable to further include a forming step. In the protective film removing step, it is also preferable to remove the drift correction mark. In the case of a black defect portion, excessive etching during drift correction can be suppressed by the protective film. In the case of a white defect portion, even if a correction film is deposited on the protective film at the time of drift correction, it can be removed in the protective film removing step.

  In the present invention, it is possible to suppress deterioration of transfer characteristics due to excessive etching around the defect portion or deposition of a correction film, and it is possible to obtain a highly accurate NIL mask.

It is a flowchart which shows an example of the manufacturing method of the mask for NIL of this invention. It is a flowchart which shows an example of the defect correction process of the manufacturing method of the mask for NIL of this invention. It is process drawing which shows an example of the manufacturing method of the mask for NIL of this invention. It is process drawing which shows an example of the manufacturing method of the mask for NIL of this invention. It is process drawing which shows the other example of the manufacturing method of the mask for NIL of this invention. It is process drawing which shows the other example of the manufacturing method of the mask for NIL of this invention. It is a flowchart which shows the other example of the manufacturing method of the mask for NIL of this invention. It is process drawing which shows the other example of the manufacturing method of the mask for NIL of this invention. It is process drawing which shows the other example of the manufacturing method of the mask for NIL of this invention. It is process drawing which shows an example of the transfer method using the mask for NIL. It is the schematic sectional drawing and top view which show an example of the drift correction mark of the mask for NIL in this invention.

  Hereinafter, the method for manufacturing the NIL mask of the present invention will be described in detail.

  A method for manufacturing an NIL mask according to the present invention is a method for manufacturing an NIL mask having a concavo-convex pattern on a main surface of a substrate, wherein a protective film is formed in an area larger than a defect area where a defect portion of the NIL mask exists. A protective film forming step to be formed; an observation step of observing the defect portion; a removal step of partially removing the protective film in the defect region to expose the defect portion; and assisting the exposed defect portion A defect repairing step having a repairing step of depositing a correction film by irradiating a charged beam while supplying a gas and etching, or irradiating a charged beam while supplying a deposition gas, and the remaining protective film And a protective film removing step to be removed.

The manufacturing method of the NIL mask of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing an example of a method for manufacturing an NIL mask according to the present invention, and FIG. 2 is a flowchart showing an example of a defect correcting process in the method for manufacturing an NIL mask according to the present invention. FIGS. 4 (g) and 4 (a) to 4 (b) are process diagrams showing an example of a method for manufacturing a mask for NIL of the present invention, which is an example of correcting a black defect portion.

  First, as shown in FIG. 1, an NIL mask manufacturing step S <b> 1 for preparing a NIL mask having a defective portion and requiring correction is performed. Specifically, as shown in FIG. 3A, an NIL mask 1 having a concavo-convex pattern on the surface and composed of a light-transmitting substrate such as a quartz substrate and having a black defect portion 10a is provided. prepare. For the defective portion, the NIL mask is inspected in advance, and the type, size, position, etc. of the defective portion are measured and stored as inspection data. Next, as shown in FIG. 1, a protective film forming step S2 for forming a protective film is performed. Specifically, as shown in FIG. 3B, the protective film 2 is formed in a region larger than the defect region A1 where the black defect portion 10a of the NIL mask 1 is present. At this time, as shown in FIGS. 3B, 3C, and 4A, the protective film formation region A2 is larger than the defect region A1, and the observation region A3 in the observation step and the correction confirmation step described later. The protective film 2 is formed to be larger than A4.

Next, as shown in FIG. 1, a defect correcting step S3 for correcting the defective portion is performed. In the defect correction step S3, first, as shown in FIG. 2, an observation step S11 for observing a defective portion is performed. Specifically, as shown in FIG. 3C, a scanning electron microscope (SEM) that irradiates an electron beam as a charged beam 11 near the defect area A1 of the NIL mask 1 or focused ions that irradiate an ion beam. Observe with a beam device. Next, in the defect correction step S3, as shown in FIG. 2, a removal step S12 for removing the protective film in the defective region is performed. Specifically, as shown in FIGS. 3D to 3E, a protective film assist gas 12 is supplied to the protective film 2 in the defect region A1, and the charged beam 11 is locally irradiated to thereby form the protective film 2 Is partially etched to expose the black defect portion 10a, and then the protective film assist gas 12 is exhausted. Next, in the defect correction step S3, as shown in FIG. 2, a correction step S13 for correcting the defective portion is performed. Specifically, as shown in FIGS. 3F to 3G, the defect assist gas 13 is supplied to the exposed black defect portion 10a, and the charged beam 11 is locally irradiated to thereby expose the black defect portion 10a. Then, the defect assist gas 13 is exhausted. Next, in the defect correction step S3, as shown in FIG. 2, a correction confirmation step S14 for observing the defect portion after correction is performed. Specifically, as shown in FIG. 4A, a scanning electron microscope (SEM) that irradiates an electron beam as a charged beam 11 near the defect region of the NIL mask 1 or a focused ion beam that irradiates an ion beam. Observe with instrument.
In the present specification, for the sake of convenience, the assist gas used when etching the protective film is referred to as the protective gas assist gas, and the assist gas used when etching the black defect portion is referred to as the defective portion assist gas. There is a case.

  Next, as shown in FIG. 1, a protective film removing step S4 for removing the protective film is performed. Specifically, as shown in FIG. 4B, the protective film 2 is removed with an etching solution or the like.

  When the black defect portion is corrected in the present invention, as shown in FIGS. 3F to 3G, the protective film 2 is formed around the defect region A1 during the correction step of etching the black defect portion 10a. Therefore, further etching of the surface of the NIL mask 1 around the black defect portion 10a due to the spread of the charged beam 11 can be suppressed.

Further, since the defect assist gas is used for correcting the black defect portion, the defect portion assist gas is attached to the surface of the NIL mask after the repair process. Normally, as shown in FIG. 3G, the defect assist gas 13 is exhausted in the correction process, but it is difficult to exhaust all the defect assist gas 13 adhering to the surface of the NIL mask 1. . Therefore, when the NIL mask is irradiated with a charged beam in the correction check process for checking the defect after correction, the surface of the NIL mask is excessively etched because the assist gas for the defect is slightly attached. There is a concern that even a fine pattern may be etched.
On the other hand, in the present invention, as shown in FIG. 4A, the surface of the NIL mask 1 is protected by the protective film 2, and the protective film formation region A2 is larger than the observation region A4 in the correction confirmation process. Therefore, even if the defect portion assist gas 13 adheres to the surface of the protective film 2, the surface of the NIL mask 1 is prevented from being further etched by the irradiation of the charged beam 11, which is inspection light, during the correction confirmation process. Can do.

Thus, in the present invention, when the defective portion is a black defect portion, it is possible to suppress excessive etching during the correction process and the correction confirmation process.
In addition, when a plurality of black defect portions are present in the NIL mask, the above-described observation process, removal process, correction process, and correction confirmation process are repeatedly performed. In this case, however, an excess in the second and subsequent observation processes is performed. Etching can also be suppressed.

  In the present invention, in the correction confirmation process, the defect region where the defect portion of the NIL mask exists is not formed with a protective film and may be excessively etched. That is, a part of the bottom surface of the concave portion of the concave / convex pattern of the NIL mask may be excessively etched. However, since the defect area is usually much smaller than the observation area in the correction confirmation process, it is considered that there is almost no influence of excessive etching. In nanoimprint lithography, the remaining film thickness of the pattern transferred to the transfer object varies depending on the height of the upper surface of the convex portion of the concavo-convex pattern of the NIL mask. Even if a part of the bottom surface of the concave portion of the concave / convex pattern is excessively etched, a defective pattern causing a problem does not occur.

  Here, in nanoimprint lithography, the remaining film thickness of the pattern transferred to the transfer object is referred to as RLT (Residual Layer Thickness). Regarding the RLT, the film thickness uniformity is strictly demanded, and for example, the difference between the maximum film thickness and the minimum film thickness is required to be suppressed to 3 nm or less. Although the RLT depends on the size and material of the concavo-convex pattern, for example, the depth of the concave portion of the concavo-convex pattern of the NIL mask (corresponding to the height of the convex portion of the pattern transferred to the transfer target) is about 50 nm. , RLT is about 10 nm. The remaining film thickness of the pattern transferred to the transfer target is the uneven pattern of the NIL mask 1 formed on the resin layer 32a formed on the substrate 31 as illustrated in FIGS. 10 (a) to 10 (b). The thickness t of the remaining film portion of the transferred resin pattern 32b when transferred.

In the present invention, since the upper surface of the convex portion of the concavo-convex pattern of the NIL mask is covered with the protective film during the correction confirmation step, it is possible to prevent the upper surface of the convex portion of the concavo-convex pattern from being excessively etched. Therefore, the remaining film thickness of the pattern transferred to the transfer target can be made uniform.
Further, when the bottom surface of the concave portion of the concavo-convex pattern is excessively etched in the defect region where the defective portion of the NIL mask exists, the bottom surface of the concave portion of the concavo-convex pattern of the NIL mask is excessive in the pattern transferred to the transfer target. Although the height of the convex portion corresponding to the etched region is higher than other regions, the defect region is a minute region compared to the observation region, so when overetching occurs in the entire conventional observation region Thus, a defective pattern does not occur over a wide range. Further, for example, the depth (design value) of the concave portion of the concave / convex pattern of the NIL mask is about 50 nm, whereas the depth at which the bottom surface of the concave portion is excessively etched during the correction confirmation process is about several nm. A defective pattern with a large difference in height does not occur.
Therefore, there is no particular problem even if the NIL mask surface in the defect region where the defect exists is excessively etched in the correction confirmation process.

5 (a) to 5 (g) and FIGS. 6 (a) to 6 (b) are process diagrams showing another example of the method for manufacturing the NIL mask of the present invention, and are examples of correcting a white defect portion. . The manufacturing method of the mask for NIL shown in FIGS. 5A to 5G and FIGS. 6A to 6B is shown in FIGS. 3A to 3G and FIGS. 4A to 4B. Similar to the manufacturing method of the NIL mask, this corresponds to the flowcharts shown in FIGS. Since the flowcharts shown in FIGS. 1 and 2 have been described above, description thereof is omitted here.
First, as shown in FIG. 5A, an NIL mask manufacturing process for preparing the NIL mask 1 having the white defect portion 10b is performed. Next, as shown in FIG. 5B, a protective film forming step is performed in which the protective film 2 is formed in a region larger than the defect region A1 where the white defect portion 10b of the NIL mask 1 is present. At this time, as shown in FIGS. 5B, 5C, and 6A, the protective film formation region A2 is larger than the defect region A1, and the observation region A3 in the observation step and the correction confirmation step described later. The protective film 2 is formed to be larger than A4.

Next, as shown in FIGS. 5C to 5G and FIG. 6A, a defect correcting step for correcting the white defect portion 10b is performed. In the defect correction step, first, as shown in FIG. 5C, a scanning type in which an electron beam is irradiated as a charged beam 21 in the vicinity of the defect area A1 of the NIL mask 1 in order to observe the white defect portion 10b. An observation step of observing with an electron microscope (SEM) or a focused ion beam apparatus that irradiates an ion beam is performed. Next, as shown in FIGS. 5D to 5E, the protective film assist gas 22 is supplied to the protective film 2 in the defect region A1, and the charged beam 21 is locally irradiated to partially cover the protective film 2. Etching is performed to expose the white defect portion 10b, and then a removal step of exhausting the protective film assist gas 22 is performed. Next, as shown in FIGS. 5F to 5G, the deposition gas 23 is supplied to the exposed white defect portion 10b and the charged beam 21 is locally irradiated, and the correction film 3 is applied to the white defect portion 10b. After depositing, a correction process for exhausting the deposition gas 23 is performed. Next, as shown in FIG. 6A, in order to observe the corrected white defect portion, a scanning electron microscope (SEM) that irradiates an electron beam as a charged beam 21 in the vicinity of the defect region of the NIL mask 1. ) And a correction confirmation step of observing with a focused ion beam apparatus that irradiates an ion beam.
Next, as shown in FIG. 6B, a protective film removing step for removing the protective film 2 with an etching solution or the like is performed.

  When the white defect portion is corrected in the present invention, as shown in FIGS. 5F to 5G, the protective film 2 is formed around the defect region A1 in the correction step of depositing the correction film 3 on the white defect portion 10b. Although not shown in the figure because it is formed, even if a correction film is further deposited on the protective film 2 around the white defect portion 10b due to the spread of the charged beam 21, the protective film removal as shown in FIG. In the process, the correction film on the protective film 2 can be removed together with the protective film 2.

Further, since the deposition gas is used to correct the white defect portion, the deposition gas is attached to the surface of the NIL mask after the correction process. Normally, as shown in FIG. 5G, the deposition gas 23 is exhausted in the correction process, but it is difficult to exhaust all the deposition gas 23 adhering to the surface of the NIL mask 1. Therefore, when the NIL mask is irradiated with a charged beam in the correction check process for checking the defect after the correction, the surface of the NIL mask is slightly deposited with a deposition gas, so that the correction film is excessively deposited. There is a concern that the correction film is deposited on the normal pattern.
In contrast, in the present invention, as shown in FIG. 6A, the protective film 2 is formed on the surface of the NIL mask 1, and the protective film formation region A2 is more than the observation region A4 in the correction confirmation process. Therefore, even if the correction film 4 is further deposited on the protective film 2 by the irradiation of the charged beam 21 as the inspection light during the correction confirmation process, the protective film is removed in the protective film removal process as shown in FIG. 2 and the correction film 4 on the protective film 2 can be removed.

As described above, in the present invention, when the defect portion is a white defect portion, even if an unnecessary correction film is deposited during the correction step and the correction confirmation step, it can be removed in the protective film removal step. It is.
In addition, when a plurality of white defect portions exist in the NIL mask, the above-described observation process, removal process, correction process, and correction confirmation process are repeatedly performed. In this case, unnecessary correction is performed in the second and subsequent observation processes. Even if the film is deposited, it can be removed in the protective film removing step.

In the present invention, in the correction confirmation step, the correction film may be further deposited in the region where the correction film is deposited. That is, the correction film may be excessively deposited on a part of the upper surface of the convex portion of the concave / convex pattern of the NIL mask. However, the region where the correction film is deposited is almost the same as the defect region where the defect portion of the NIL mask exists, and is a minute region compared to the observation region. Therefore, in the pattern transferred to the transfer target, the remaining film thickness corresponding to the region where the correction film is excessively deposited on the upper surface of the convex portion of the concavo-convex pattern of the NIL mask is smaller than the other regions in the minute region. However, the remaining film thickness does not become uneven over a wide range as in the case where an unnecessary correction film is deposited over the entire observation region. Therefore, a defective pattern does not occur over a wide range. Further, for example, the height (design value) of the convex portion of the concavo-convex pattern of the NIL mask is about 50 nm, whereas the height of the correction film deposited excessively during the correction confirmation process is about several nm. A defective pattern with a large difference in height does not occur.
Therefore, there is no particular problem even if the correction film is excessively deposited in the defect region where the defect portion of the NIL mask exists in the correction confirmation process.

  Therefore, in the present invention, it is possible to suppress a change in the transfer characteristics of the NIL mask during the defect correction process, and to manufacture a highly accurate NIL mask having excellent transfer characteristics with a high yield.

FIG. 7 is a flowchart showing another example of the method for manufacturing the NIL mask of the present invention, and FIGS. 8A to 8G and FIGS. 9A to 9D show the manufacturing of the NIL mask of the present invention. It is process drawing which shows the other example of a method, Comprising: It is an example which corrects a black defect part.
First, as shown in FIG. 7, an NIL mask manufacturing step S1 for preparing a NIL mask that has a defective portion and needs to be corrected is performed. Specifically, as shown in FIG. 8A, an NIL mask 1 having a black defect portion 10a is prepared. Next, as shown in FIG. 7, a protective film forming step S2 for forming a protective film is performed. Specifically, as shown in FIG. 8B, the protective film 2 is formed in a region larger than the defect region A1 where the black defect portion 10a of the NIL mask 1 is present. At this time, as shown in FIGS. 8B, 8C, and 9A, the protective film formation region A2 is larger than the defect region A1, and the observation region A3 in the observation step and the correction confirmation step described later. The protective film 2 is formed to be larger than A4. Next, as shown in FIG. 7, a drift correction mark forming step S5 for forming a drift correction mark is performed. More specifically, as shown in FIG. 8B, a protruding drift correction mark 5 is formed on the protective film 2 in a region other than the defect region A1.

Next, as shown in FIG. 7, a defect correcting step S3 for correcting the defective portion is performed. In the defect correction step S3, first, as shown in FIG. 2, an observation step S11 for observing a defective portion is performed. Specifically, as shown in FIG. 8C, a scanning electron microscope (SEM) that irradiates an electron beam as a charged beam 11 near the defect area A1 of the NIL mask 1 or focused ions that irradiate an ion beam. Observe with a beam device. At this time, the drift correction mark 5 is also scanned with the charged beam 11 and the position of the drift correction mark 5 is detected from the secondary electron image.
Next, in the defect correction step S3, as shown in FIG. 2, a removal step S12 for removing the protective film in the defective region is performed. Specifically, as shown in FIG. 8D, after supplying the protective film assist gas 12 to the protective film 2 in the defect region A1, the drift correction mark 5 is again detected in order to detect the trajectory of the charged beam 11. And the position of the drift correction mark 5 is detected from the secondary electron image. Then, the drift amount is calculated from the difference from the position of the drift correction mark 5 detected before the defect correcting step, and drift correction is performed. Next, as shown in FIGS. 8E to 8F, the protective film 2 is locally irradiated with the charged beam 11 on the protective film 2 in the defect area A1 to which the protective film assist gas 12 is supplied, so that the protective film 2 is applied. Etching is partially performed to expose the black defect portion 10a. At this time, the removal of the protective film 2 is started, and after a predetermined time has elapsed, in order to detect the trajectory of the charged beam 11, the drift correction mark 5 is again scanned with the charged beam 11, and the drift correction mark is detected from the secondary electron image. 5 position is detected. Then, the drift amount is calculated from the difference from the position of the drift correction mark 5 detected before the defect correction step, drift correction is performed, and the removal of the protective film 2 is resumed. Such detection of the position of the drift correction mark, drift correction, and restart of the protective film removal are repeated, and the protective film in the defective region is removed with high accuracy. Thereafter, as shown in FIG. 8F, the protective film assist gas 12 is exhausted.
Next, in the defect correction step S3, as shown in FIG. 2, a correction step S13 for correcting the defective portion is performed. Specifically, as shown in FIG. 8G, after supplying the defect assist gas 13 to the exposed black defect portion 10a, the drift correction mark 5 is again set to detect the trajectory of the charged beam 11. Scanning with the charged beam 11 detects the position of the drift correction mark 5 from the secondary electron image. Then, the drift amount is calculated from the difference from the position of the drift correction mark 5 detected before the defect correcting step, and drift correction is performed. Next, as shown in FIGS. 9A to 9B, the black defect portion 10a supplied with the defect portion assist gas 13 is locally irradiated with the charged beam 11 to etch the black defect portion 10a. . At this time, etching of the black defect portion 10a is started, and after a predetermined time has elapsed, the drift correction mark 5 is again scanned with the charged beam 11 in order to detect the trajectory of the charged beam 11, and the drift correction mark 5 is scanned from the secondary electron image. The position of the mark 5 is detected. Then, the drift amount is calculated from the difference from the position of the drift correction mark 5 detected before the defect correcting step, drift correction is performed, and the etching of the black defect portion 10a is resumed. Such detection of the position of the drift correction mark, drift correction, and restart of the black defect portion etching are repeated to correct the defect portion with high accuracy. Thereafter, as shown in FIG. 9B, the defect assist gas 13 is exhausted.
Next, in the defect correction step S3, as shown in FIG. 2, a correction confirmation step S14 for observing the defect portion after correction is performed. Specifically, as shown in FIG. 9C, a scanning electron microscope (SEM) that irradiates an electron beam as a charged beam 11 in the vicinity of a defect region of the NIL mask 1 or focused ions that irradiate an ion beam. Observe with a beam device.

  Next, as shown in FIG. 7, a protective film removing step S4 for removing the protective film is performed. Specifically, as shown in FIG. 9D, the protective film 2 and the drift correction mark 5 are removed with an etching solution or the like.

  Here, the drift correction will be described. In the defect correction method using a charged beam, charge stagnation occurs by irradiating the charged beam, and a drift of the charged beam occurs at the time of defect correction, which makes it difficult to correct a desired defect. Thus, attempts have been made to form drift correction marks and perform drift correction when correcting defects, but such drift correction is difficult to apply to NIL masks, although it can be applied to photomasks. For example, the drift correction mark has a through hole or a protrusion. In the case of the through hole, in the NIL mask, the fine uneven pattern is destroyed by forming the through hole, or the through hole is resolved in order to transfer at the same magnification. In the case of protrusions, the NIL mask and the transfer target cannot be brought into close contact with each other. Therefore, in the NIL mask, it is difficult to form drift correction marks such as through holes and protrusions, and studies have been made to perform drift correction using the edges of the concavo-convex pattern. However, in the NIL mask, the direction of the edge of the concavo-convex pattern is often aligned in one direction, such as a line-and-space pattern. Among them, even if drift correction in the X direction can be performed, it is difficult to perform drift correction in the Y direction, and it is difficult to accurately perform drift correction.

  On the other hand, in the present invention, since the drift correction mark is formed on the protective film, the drift correction mark can be removed together with the protective film in the protective film removing step. Therefore, the drift correction mark can be provided also in the NIL mask, and the drift correction can be accurately performed using the drift correction mark in the defect correction process, so that highly accurate defect correction is possible.

  Further, when drift correction is performed during the correction process as shown in FIGS. 8G to 9B, the defect portion assist gas 13 is attached to the surface of the NIL mask 1, and thus the charged beam 11. When the position of the drift correction mark 5 is detected by scanning this, there is a concern that the surface of the NIL mask 1 around the drift correction mark 5 is excessively etched and a normal pattern is etched. On the other hand, in the present invention, since the protective film 2 is formed, it is possible to suppress further etching of the surface of the NIL mask 1 around the drift correction mark 5.

  Further, although not illustrated in the case of correcting the white defect portion and performing the drift correction, it is the same as the above case, and in order to form the drift correction mark on the protective film, the vicinity of the drift correction mark is formed. Even if a correction film is further deposited on the protective film, the correction film on the protective film can be removed together with the protective film in the protective film removing step.

  Thus, in the present invention, when the black defect portion is corrected, it is possible to suppress excessive etching at the time of drift correction. Further, when correcting the white defect portion, even if an unnecessary correction film is deposited at the time of drift correction, it can be removed in the protective film removing step.

  Hereafter, the manufacturing method of the mask for NIL of this invention is demonstrated for every process.

1. Protective film forming step The protective film forming step in the present invention is a step of forming a protective film in a region larger than the defective region where the defective portion of the NIL mask exists.

As a material used for the protective film, it is possible to protect the surface of the NIL mask during the defect correction process described later, and it is possible to remove only the protective film in the protective film removal process described later. It is not particularly limited as long as it is a metal material such as a metal such as chromium, aluminum, iron, and tantalum, a metal oxide such as iron oxide, a metal nitride such as TaN and TaBN, and a metal silicide such as molybdenum silicide. And conductive polymers such as silicon, carbon and polyaniline.
Especially, it is preferable that a protective film is a metal film which consists of said metal material. This is because the metal material has a good etching selectivity with respect to the substrate constituting the NIL mask, and it is easy to remove only the protective film in the protective film removing step described later. In addition, since the metal material can form a thin film, the defective portion can be easily observed after the protective film forming step even if the defective portion is minute. Furthermore, film formation is easy even in a relatively wide area.
Of these metal materials, chromium is particularly preferable. This is because when the defect portion is a black defect portion, the chromium film is difficult to be etched with the assist gas. In consideration of the etching selectivity with respect to the substrate constituting the NIL mask, chromium is preferable.

The protective film formation region may be larger than the defect region where the defect portion of the NIL mask exists. Especially, it is preferable that a protective film formation area is more than the observation area in the observation process in the below-mentioned defect correction process and the correction confirmation process, and it is preferable that it is larger than an observation area. This is because the protective film can protect the NIL mask surface not only in the correction process but also in the observation process and the correction confirmation process. In addition, the observation area | region in an observation process and a correction confirmation process is the same area | region normally.
Here, the irradiation area of the charged beam in the correction process for correcting the defect portion is limited to the defect region where the defect portion exists in order to prevent excessive etching to a normal pattern or deposition of a correction film. Is done. On the other hand, in the correction confirmation process for confirming the defect part after the correction, since it is necessary to compare with the surrounding area in order to confirm the defect part after the correction, the charged beam scanning area, that is, the observation area has a defect part. It includes not only the defect area but also the periphery of the defect area. Therefore, it is particularly preferable that the protective film formation region is larger than the observation region.

The protective film may be formed partially on the NIL mask or may be formed on the entire surface.
Specifically, in an NIL mask that is suitably used for forming a fine pattern having a pattern width of 100 nm or less, for example, a defect portion having a size of about several nm to several hundred nm is likely to be corrected. Therefore, when the protective film is partially formed on the NIL mask, the observation region can be easily set as the size of the protective film formation region when correcting the defective portion having the above size. Therefore, it is preferably 1 μm × 1 μm or more, more preferably 3 μm × 3 μm or more. On the other hand, in this case, the size of the protective film formation region is preferably 100 μm × 100 μm or less, and more preferably 10 μm × 10 μm or less, from the viewpoint of easy formation of the protective film and ease of peeling of the protective film.

  In addition, as a formation position of the protective film, the protective film 2 may be formed only on the surface of the concavo-convex pattern of the NIL mask 1 as illustrated in FIG. It may be formed not only on the surface but also on the side surface.

The method for forming the protective film is not particularly limited as long as the protective film can be uniformly formed in a region larger than the defect region of the NIL mask. For example, a physical method such as sputtering or vacuum evaporation is used. Examples include vapor deposition (PVD), chemical vapor deposition (CVD) such as electron beam CVD, and atomic layer deposition (ALD).
Further, when forming the protective film, the protective film may be formed using an apparatus different from the defect correcting apparatus before the NIL mask is arranged in the defect correcting apparatus used in the defect correcting process described later. Alternatively, the protective film may be formed by using a gas supply means for supplying a gas such as a deposition gas provided in the defect correcting apparatus. When the protective film is formed using an apparatus different from the defect correcting apparatus, it is easy to form a protective film in a relatively large area, select a material, and adjust the protective film formation area. In this case, when there are a plurality of defective portions, it is advantageous that a protective film can be efficiently formed in a large region. On the other hand, when the protective film is formed using a gas supply means or the like in the defect correction apparatus, it is easy to form a local protective film.

  The thickness of the protective film is not particularly limited as long as it does not fill the concavo-convex pattern on the NIL mask surface and can protect the NIL mask surface during the defect correction step. For example, the thickness can be about 1 nm to 20 nm, preferably 1 nm to 15 nm, and more preferably 1 nm to 7 nm. If the protective film is too thick, it may be difficult to observe the defective part after the protective film forming step in the case of a minute defective part.

2. Defect correction step The defect correction step in the present invention includes an observation step of observing the defect portion, a removal step of partially removing the protective film in the defect region and exposing the defect portion, and the exposed defect portion. And a correction step of depositing a correction film by irradiating a charged beam while etching while supplying an assist gas or irradiating a charged beam while supplying a deposition gas.

The defect correction step preferably includes a correction confirmation step of irradiating the charged beam and confirming the corrected defect portion after the correction step. This is because, in the case of a black defect portion, by forming a protective film, it is possible to suppress excessive etching not only during the correction process but also during the correction confirmation process. Further, in the case of a white defect portion, even if an unnecessary correction film is deposited not only during the correction process but also during the correction confirmation process by forming a protective film, together with the protective film in the protective film removal process described later This is because an unnecessary correction film can be removed.
Hereinafter, each process in the defect correction process will be described.

(1) Observation process The observation process in a defect correction process is a process of observing a defective part. Prior to repairing the defective part, the defective part is observed.

In the observation step, for example, the defect portion can be observed by irradiating a charged beam.
The charged beam is not particularly limited as long as the defect portion can be inspected, and a charged beam used for correction of a black defect portion and a white defect portion described later can be used. In the case of an electron beam, it can be examined by an electron microscope such as a scanning electron microscope (SEM).
The charged beam in the observation process and the charged beam in the correction process described later may be the same or different.

  In the observation step, only the vicinity of the defect region may be inspected, or the entire NIL mask may be inspected.

(2) Removal Step The removal step in the defect correction step is a step of partially removing the protective film in the defective area and exposing the defective portion.

  The method for removing the protective film is not particularly limited as long as it can remove only the protective film in the defective region. For example, a method of etching by irradiating a charged beam while supplying an assist gas. Is used.

  The charged beam is not particularly limited as long as only the protective film in the defective region can be etched locally, and examples thereof include an electron beam and an ion beam, which are used for correcting a black defect portion described later. Can be similar to

The assist gas is not particularly limited as long as it is a gas that can etch the protective film, and is appropriately selected according to the type of material of the protective film. The assist gas may be a single component gas or a mixed gas containing a plurality of types of components.
For example, when the protective film contains chromium, the assist gas contains a mixed gas containing xenon fluoride (XeF ₂ ) and oxygen (O ₂ ), xenon fluoride (XeF ₂ ), and water vapor (H ₂ O). A mixed gas is preferably used.
For example, when the protective film contains a conductive polymer, the assist gas may be a gas that generates OH ions by charged beam irradiation or xenon fluoride that reacts with an organic substance to generate vaporizable gas by charged beam irradiation. (XeF ₂ ) is used. The gas that generates OH ions is not particularly limited as long as it is a substance that has a hydroxyl group and forms OH ions by irradiation with a charged beam in a gasified state. However, it is easy and preferable to use water after steaming. Water vapor generates activated OH ions by charge energy. What is necessary is just to supply about 1 Torr to 0.5 Torr of water vapor as gas, for example. The charged beam irradiation area of the protective film is directly decomposed by the activated OH ions, and the protective film in the correction area is removed to expose the defective portion. Further, the XeF ₂ gas reacts with an organic substance to generate a vaporizable CF ₄ gas and the like, removes the protective film in the correction region, and exposes the defective portion.

  Examples of the assist gas supply method include a method of spraying an assist gas locally on the protective film, and a method of disposing an NIL mask in an assist gas atmosphere.

  When etching the protective film in the defect region, the etching proceeds while confirming the secondary electron signal of the material contained in the protective film caused by the irradiation of the charged beam, and the secondary electron signal of the material contained in the protective film disappears. By stopping the etching at that time, the protective film in the defective region can be etched with a high selection ratio while suppressing the etching of the NIL mask surface.

(3) Repairing process The repairing process in the defect repairing process involves etching the exposed defect portion by irradiating a charged beam while supplying an assist gas, or irradiating a charged beam while supplying a deposition gas. This is a step of depositing a correction film.
In the present invention, the defect portion of the NIL mask may be either a black defect portion or a white defect portion. Among these, in the present invention, it is preferable to correct the black defect portion.
Hereinafter, the description will be made separately for the black defect portion and the white defect portion.

(A) Black defect portion When the defect portion is a black defect portion, in the correction step, the black defect portion is etched by irradiating a charged beam while supplying an assist gas to the black defect portion.

  The charged beam is not particularly limited as long as only the black defect portion can be locally etched, and examples thereof include an electron beam and an ion beam. Among these, an electron beam is preferable. This is because the electron beam can be narrowed down to several nanometers and has high correction accuracy, and since the mass of the charged particles is smaller than that of the ion beam, the NIL mask is less damaged.

The assist gas is not particularly limited as long as it is a gas capable of etching the black defect portion. The assist gas may be a single component gas or a mixed gas containing plural kinds of gases. For example, when an electron beam is used, the assist gas includes xenon fluoride (XeF ₂ ). On the other hand, when an ion beam is used, examples of the assist gas include xenon fluoride (XeF ₂ ) and iodine (I ₂ ).

  Among these, when the NIL mask contains silicon oxide and the protective film contains chromium, xenon fluoride is preferably used as the assist gas. In this case, the etching rate of silicon oxide is approximately 10 times the etching rate of chromium. Therefore, in the correction process, even if the charged beam has a spread, the black defect portion can be etched with a high selection ratio while suppressing the protective film around the black defect portion from being etched. Further, in the correction confirmation step described later, even if the assist gas remains on the surface of the protective film, the protective film can be suppressed from being etched.

  Examples of the supply method of the assist gas include a method of spraying the assist gas locally on the black defect portion, a method of arranging the NIL mask in the assist gas atmosphere, and the like. When the NIL mask is placed in the assist gas atmosphere, the assist gas adheres to the entire surface of the NIL mask. Therefore, in the protective film forming step, as described above, a protective film is formed on the entire surface of the NIL mask. It is preferable to form. Thereby, excessive etching of the NIL mask surface in the defect correcting step can be suppressed.

The etching depth in the correction process is appropriately selected according to the depth of the concave portion of the concave / convex pattern of the NIL mask.
Further, as described above, in the correction confirmation process described later, the bottom surface of the concave portion of the concave / convex pattern may be excessively etched in the defective region where the defective portion of the NIL mask exists. Therefore, the etching depth during the correction process may be set shallower in consideration of the depth etched excessively during the correction confirmation process. For example, when the etching depth at the correction confirmation step is h1, the etching depth at the correction step may be adjusted to a value obtained by subtracting h1.

(B) White defect portion When the defect portion is a white defect portion, in the correction process, a charged beam is irradiated while supplying a deposition gas to the white defect portion to deposit a correction film.

  The charged beam is not particularly limited as long as the correction film can be locally deposited only on the white defect portion, and can be the same as that used for correction of the black defect portion.

As the deposition gas, for example, a gas generally used when a CVD method using a charged beam is applied can be used. In addition, the deposition gas is required to be able to deposit a correction film having a hardness that does not deform even when the NIL mask is pressed against the transfer object, and does not react with the transfer object. For example, when using an electron beam, examples of the deposition gas include phenanthrene, tungsten carbonyl (W (CO) ₆ ), tungsten fluoride (WF ₆ ), and tetraethoxysilane (TEOS). On the other hand, when an ion beam is used, examples of the deposition gas include phenanthrene, tungsten carbonyl (W (CO) ₆ ), and tetraethoxysilane (TEOS).

  Examples of the method for supplying the deposition gas include a method in which a deposition gas is locally sprayed on a white defect portion, and a method in which an NIL mask is disposed in the deposition gas atmosphere. When the NIL mask is disposed in the deposition gas atmosphere, the deposition gas adheres to the entire surface of the NIL mask. Therefore, in the protective film forming step, as described above, the entire surface of the NIL mask is disposed. It is preferable to form a protective film. Thereby, even if an unnecessary correction film is deposited on the surface of the NIL mask in the defect correction process, the unnecessary correction film can be removed together with the protective film in the protective film removal process.

The thickness of the correction film is appropriately selected according to desired transfer characteristics.
In addition, as described above, in the correction confirmation process described later, a correction film may be further deposited in a region where the correction film is deposited. Therefore, the thickness of the correction film deposited during the correction process may be set to be lower in consideration of the thickness of the correction film further deposited during the correction confirmation process. For example, when the thickness of the correction film deposited during the correction confirmation step is h2, the correction film thickness may be adjusted to a value obtained by subtracting h2. In this case, the remaining film thickness of the pattern transferred to the transfer object can be made uniform.

(C) Others In the correction step, as described above, it is preferable to perform drift correction using the drift correction mark. High-precision defect correction is possible.

(4) Correction confirmation process The correction confirmation process of a defect correction process is a process which confirms the said defect part after correction | amendment by irradiating a charged beam.

  The charged beam is not particularly limited as long as it can inspect the corrected defective portion, and a charged beam used for correcting the black defect portion and the white defect portion can be used. In the case of an electron beam, it can be examined by an electron microscope such as a scanning electron microscope (SEM).

  The charged beam in the correction confirmation step and the charged beam in the correction step may be the same or different, but are preferably the same.

  In the correction confirmation process, only the vicinity of the defect area may be inspected, or the entire NIL mask may be inspected. In particular, as described above, since the protective film formation region is preferably larger than the observation region in the correction confirmation step, it is preferable to appropriately select the protective film formation region according to the observation region in the correction confirmation step.

(5) Other processes In the defect correction process, when it is determined that the defective part has not been corrected in the correction check process, the above correction process and the correction check process are repeated as shown in FIG. May be.
In addition, when there are a plurality of defect portions in the NIL mask, the above observation process, removal process, correction process, and correction confirmation process may be repeated.

3. Protective film removing step The protective film removing step in the present invention is a step of removing the remaining protective film.

The method for removing the protective film is not particularly limited as long as only the protective film can be removed, but wet etching or dry etching is preferably used, and wet etching is particularly preferable. This is because in wet etching, an unnecessary correction film and drift correction mark formed on the protective film can be easily removed together with the protective film.
In the case of wet etching, for example, when the protective film contains chromium, an aqueous solution containing ceric ammonium nitrate and perchloric acid is used. Further, when the protective film contains a conductive polymer, water or an alkaline aqueous solution is used. When the protective film contains aluminum, a mixed solution of phosphoric acid and nitric acid and a mixed solution of hydrochloric acid and sulfuric acid are used.
As dry etching, for example, when the protective film contains chromium, a mixed gas of chlorine and oxygen is used. Further, when the protective film contains carbon, ozone plasma, oxygen plasma, or NH ₃ plasma can be used.

4). Drift correction mark forming step In the present invention, a drift correction mark forming step of forming a drift correction mark on the protective film in a region other than the defective region after the protective film forming step and before the defect correcting step. It is preferable to carry out. In this case, the drift correction mark is also removed in the protective film removing step.
In the present invention, since the drift correction mark is formed on the protective film, the drift correction mark can be removed together with the protective film in the protective film removing step. Therefore, it is possible to provide a drift correction mark, which has been difficult to apply in the past in the NIL mask, and in the defect correction process, it is possible to accurately perform drift correction using the drift correction mark. Defect correction is possible.
Further, in the present invention, by forming a protective film, it is possible to suppress excessive etching at the time of drift correction when correcting the black defect portion, and at the time of drift correction when correcting the white defect portion. Even if an unnecessary correction film is deposited, it can be removed in the protective film removal step.

  The material used for the drift correction mark is not particularly limited as long as secondary electrons can be detected by scanning with a charged beam. For example, metals such as chromium, aluminum, iron, and tantalum, iron oxide And metal oxides such as TaN and TaBN, metal silicides such as molybdenum silicide, silicon, carbon, and silicon oxide. Among them, the drift correction mark is preferably a metal film made of the above metal material, and chromium is particularly preferable among the above metal materials. When the material of the drift correction mark is the same as that of the protective film, the drift correction mark can be reliably removed simultaneously with the protective film. Moreover, when using chromium, it is preferable from a viewpoint which can utilize the existing equipment for photomasks.

The formation position of the drift correction mark is not particularly limited as long as it is on a protective film in a region other than the defective region, but is preferably formed on the protective film around the defective region.
Further, the drift correction mark 5 may be disposed on the convex portion of the concave-convex pattern of the NIL mask 1 as illustrated in FIG. 11A, and on the concave portion as illustrated in FIG. It may be arranged, and may be arranged over a convex part and a crevice so that it may illustrate in Drawing 11 (d) and (e). 11A and 11B are cross-sectional views taken along the line AA in FIG. 11C, and FIGS. 11D and 11E are cross-sectional views taken along the line AA in FIG.
When the drift correction mark is arranged on the convex portion of the concavo-convex pattern, secondary electrons are easily detected. On the other hand, when the drift correction mark is arranged over the convex and concave portions of the concavo-convex pattern, secondary electrons can be easily detected and the drift correction mark can be enlarged.

  Further, the drift correction mark is formed only on the surface of the concave / convex pattern of the NIL mask 1 as illustrated in FIGS. 11A, 11B, 11D, and 11E. Although not shown, the drift correction mark may be formed not only on the surface of the concavo-convex pattern but also on the side surface.

  The number of drift correction marks is not particularly limited as long as drift correction can be performed, but it is preferable to form drift correction marks at four locations around the defect region. This is because the drift correction can be performed accurately.

The method for forming the drift correction mark is not particularly limited as long as it is a method that can be formed on the protective film other than the defect region. For example, a CVD method using a charged beam may be used. In the CVD method using a charged beam, the charged beam and deposition gas can be the same as the charged beam and deposition gas used to correct the white defect portion.
Further, when forming the drift correction mark, the drift correction mark is formed using a gas supply means for supplying a gas such as a deposition gas provided in the defect correction apparatus used in the defect correction step. Can be formed. In this case, it is easy to form a local drift correction mark.

  The thickness of the drift correction mark is not particularly limited as long as secondary electrons can be detected by scanning with a charged beam, but in particular, the height of the convex portion of the concavo-convex pattern of the NIL mask is 100%. On the other hand, the thickness is preferably several tens% or more, for example, about 10 nm to 50 nm.

  The size of the drift correction mark is not particularly limited as long as secondary electrons can be detected by scanning with a charged beam. For example, the width of the drift correction mark is about 10 nm to 50 nm. Can do.

  The shape of the drift correction mark is not particularly limited as long as it is a protrusion, and the shape in plan view and the cross-sectional shape are not particularly limited and can be any shape.

Further, after the drift correction mark is formed, the position of the drift correction mark is detected. Detection of the position of the drift correction mark can be performed in the observation process of the defect correction process. At this time, the positions of the drift correction mark and the defect portion are specified, and the relative position of the drift correction mark is also determined in advance. I ask for it.
For example, a charged beam is irradiated and the position of the drift correction mark is detected by a secondary electron signal. The charged beam is similar to a charged beam used for correcting a black defect portion and a white defect portion described later, and examples thereof include an electron beam and an ion beam.

5. NIL Mask Manufacturing Process In the present invention, an NIL mask manufacturing process for manufacturing an NIL mask having a concavo-convex pattern on the main surface of the substrate is usually performed before the protective film forming process. A defect inspection is performed on the NIL mask in advance, and the NIL mask from which a defective portion that needs to be corrected is detected is subjected to the protective film forming step.

The substrate is preferably a light transmissive substrate. Examples of the material constituting the light transmissive substrate include synthetic quartz glass, soda glass, fluorite, and calcium fluoride. Above all, it has a proven track record as a photomask substrate, has a stable quality, can be made into an integrated structure by forming an uneven pattern, and can form a fine uneven pattern with high precision. Glass is preferably used.
The light-transmitting substrate preferably has a light transmittance of 85% or more at a wavelength of 300 nm to 450 nm.

  The shape and dimensions of the concavo-convex pattern can be the same as that of a general NIL mask.

  Further, the method for forming the concave / convex pattern can be the same as a general method for producing a mask for NIL. For example, blanks in which a hard mask layer and a resist layer are sequentially laminated on a substrate are prepared, and a resist layer is prepared. And the hard mask layer is etched using the patterned resist layer as a mask to remove the resist layer, and the substrate is etched using the etched hard mask layer as a mask to remove the hard mask layer.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  The following examples illustrate the present invention in more detail.

  First, as shown in FIG. 3A, an NIL mask 1 having a concavo-convex pattern on the surface and having a black defect portion 10a made of a light-transmitting substrate was prepared. A synthetic quartz substrate having a length of 152 mm, a width of 152 mm, and a thickness of 0.25 inches is used as the light transmissive substrate, and the concavo-convex pattern has a recess depth of 50 nm and a protrusion and recess width of 20 nm. A line and space pattern was used. The NIL mask 1 was inspected in advance, and the type, size, position, etc. of the defective portion were measured and stored as inspection data.

Next, as shown in FIG. 1, a protective film forming step S2 for forming a protective film was performed. In this embodiment, the protective film is formed in the defect correction apparatus using the CVD function of the defect correction apparatus. Specifically, as shown in FIG. 3B, the size of the black defect portion 10a of the NIL mask 1 is X direction: 10 nm, the Y direction: 10 nm, and the size of the defect region A1 (X direction: The protective film 2 made of Cr was formed in a region (X direction: 3000 nm, Y direction: 3000 nm) larger than 10 nm, Y direction: 10 nm). The thickness of the protective film 2 was 2 nm. At this time, Cr (CO) ₆ is supplied as an assist gas for forming the protective film, and a Cr protective film is formed by irradiating an electron beam in the X direction: 3000 nm and Y direction: 3000 nm centering on the black defect 10a. It was done. The protective film formation region was a region sufficiently wider than the observation region in the subsequent observation step with a scanning electron microscope (SEM).

  Next, as shown in FIG. 1, a defect correcting step S3 for correcting the defective portion was performed. In the defect correction step S3, first, as shown in FIG. 2, an observation step S11 for observing a defective portion was performed. In this example, the defect portion was observed in the defect correction apparatus using a scanning electron microscope provided in the defect correction apparatus. Specifically, as shown in FIG. 3C, the vicinity of the defect area A1 of the NIL mask 1 is observed with a scanning electron microscope (SEM) that irradiates an electron beam as the charged beam 11, and the black defect 10a is observed. The coordinates were specified. The observation area A3 at that time was set to X direction: 1000 nm and Y direction: 1000 nm.

Next, in the defect correction step S3, as shown in FIG. 2, a removal step S12 for removing the protective film in the defective region was performed. Specifically, as shown in FIGS. 3D to 3E, the protective film 2 in the defect region A1 contains xenon fluoride (XeF ₂ ) and water vapor (H ₂ O) as the protective film assist gas 12. The mixed gas was supplied and the charged beam 11 was locally irradiated to partially etch the Cr protective film 2 to expose the black defect portion 10a, and then the protective film assist gas 12 was exhausted.

Next, as shown in FIG. 2, a correction step S13 for correcting the defective portion was performed. Specifically, as shown in FIGS. 3F to 3G, xenon fluoride (XeF ₂ ) is supplied to the exposed black defect portion 10a as the defect portion assist gas 13 to locally supply the charged beam 11. After the irradiation and etching of the black defect portion 10a, the defect portion assist gas 13 was exhausted.

  Next, as shown in FIG. 2, a correction confirmation step S14 for observing the defective portion after correction was performed. Specifically, as shown in FIG. 4A, the vicinity of the defect region of the NIL mask 1 was observed with a scanning electron microscope (SEM) that irradiates an electron beam as a charged beam 11. The observation region A4 at that time was set to X direction: 1000 nm and Y direction: 1000 nm. As a result, it was confirmed that the defective portion was corrected correctly.

  Next, as shown in FIG. 1, a protective film removing step S4 for removing the protective film was performed. Specifically, as shown in FIG. 4B, the protective film 2 was removed with an etching solution. The corrected NIL mask was set in a wet etching apparatus, and etching was performed using an aqueous solution containing ceric ammonium nitrate and perchloric acid suitable for Cr. After the etching, the protective film was removed, and a NIL mask with a corrected defect could be produced.

  In the method for manufacturing a mask for NIL of the present invention, (1) suppression of excessive etching of the observation region in the observation step, (2) suppression of excessive etching around the defect portion during the correction step, and (3) correction correction step The effect of suppressing excessive etching in the observation region was obtained. Due to these effects, it was possible to suppress a change in transfer characteristics of the NIL mask during the defect correction process, and to manufacture a highly accurate NIL mask having excellent transfer characteristics with a high yield.

DESCRIPTION OF SYMBOLS 1 ... NIL mask 2 ... Protective film 3, 4 ... Correction film 5 ... Drift correction mark 10a ... Black defect part 10b ... White defect part 11, 21 ... Charge beam 12, 22 ... Assist gas for protective film 13 ... Defect part Assist gas 23 ... deposition gas A1 ... defect region A2 ... protection film formation region A3, A4 ... observation region

Claims (5)

A method for manufacturing a mask for nanoimprint lithography having a concavo-convex pattern on a main surface of a substrate,
A protective film forming step of forming a protective film in a region larger than a defect region where a defect portion of the mask for nanoimprint lithography exists;
An observation step of observing the defect portion, a removal step of partially removing the protective film in the defect region to expose the defect portion, and a charged beam while supplying an assist gas to the exposed defect portion A defect correction step having a correction step of irradiating and etching, or irradiating a charged beam while supplying a deposition gas and depositing a correction film;
And a protective film removing step for removing the remaining protective film. A method for producing a mask for nanoimprint lithography.   2. The method for manufacturing a mask for nanoimprint lithography according to claim 1, wherein the defect correction step further includes a correction confirmation step of confirming the defect portion after the correction by irradiating a charged beam after the correction step. .   3. The nanoimprint lithography mask according to claim 1, wherein the nanoimprint lithography mask is light transmissive, the substrate is a light transmissive substrate, and the protective film is a metal film. 4. Manufacturing method.   The method for manufacturing a mask for nanoimprint lithography according to any one of claims 1 to 3, wherein the method for removing the protective film in the protective film removing step is wet etching or dry etching. A drift correction mark forming step of forming a drift correction mark on the protective film in a region other than the defect region after the protective film formation step and before the defect correction step;
5. The method of manufacturing a mask for nanoimprint lithography according to claim 1, wherein the drift correction mark is also removed in the protective film removing step. 6.

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