JP5445714B2 - Mold for nanoimprint lithography and method for manufacturing the same - Google Patents

Description

  The present invention relates to a mold used in nanoimprint lithography for transferring a fine uneven pattern to a curable resin formed on a substrate to be transferred, and a method for manufacturing the same.

  In recent years, especially in the manufacture of semiconductor devices, due to further progress in miniaturization, the limits of conventional photolithography methods are being pointed out. Further, in the manufacturing by the conventional photolithography method, the exposure apparatus and the like are becoming extremely expensive, and the price of the photomask to be used is also increased.

  On the other hand, the nanoimprint method (also called imprint method) proposed by Chou et al. In Princeton University in 1995 is a fine pattern formation technology having a high resolution of about 10 nm while the apparatus price and the materials used are low. (Patent Document 1).

In the nanoimprint method, a mold (also referred to as a template, a stamper, or a mold) in which a nanometer-sized uneven pattern is previously formed on the surface is pressed against a resin formed on the surface of a substrate to be transferred such as a semiconductor wafer, and the resin Is a technique for transferring the concavo-convex pattern by mechanically deforming the substrate and processing the substrate to be transferred using the resin to which the pattern is transferred as a resist mask.
Once a mold is manufactured, nanostructures can be easily and repeatedly formed, so that high throughput is obtained and economical, and in recent years, application to various fields is expected, not limited to semiconductor devices.

As such an imprint method, there are known a thermal imprint method in which a concavo-convex pattern is transferred by heat using a thermoplastic resin, and a photo imprint method in which a concavo-convex pattern is transferred by ultraviolet rays using a photocurable resin. (Patent Document 2).
The optical imprint method can transfer a pattern at a low applied pressure at room temperature, and does not require a heating / cooling cycle like the thermal imprint method and does not cause dimensional changes due to mold or resin heat. It is said that it is excellent in terms of productivity.

As described above, in the nanoimprint method, a desired pattern is transferred by pressing the mold transfer pattern against the resin on the substrate to be transferred. Therefore, the area other than the area where the desired transfer pattern is formed (transfer area) The region (non-transfer region) is usually in the form of being dug deeper into the mold than the transfer region in order to avoid contact with the substrate to be transferred and the resin.
That is, the mold for nanoimprint lithography usually has a mesa structure in which the surface of the transfer region is formed at a predetermined height from the surface of the non-transfer region.

Here, in a conventional photomask for photolithography, a name mark indicating the name and model number of the photomask in an area (non-exposed area) other than an area (exposed area) where a device pattern as a transfer pattern is formed. Or an ID code or an alignment mark (Patent Document 3).
In the conventional photomask, since the above-described exposed area and non-exposed area are on the same plane, the above-described mark is usually formed in the same process as the formation of the device pattern. Specifically, the mark as described above was formed in the same process as the device pattern drawing, and was formed by etching in the same process as the device pattern etching.

JP-T-2004-504718 JP 2002-93748 A JP 2003-75983 A

  However, when a name mark or the like indicating the product name or model number of the mold is formed on the nanoimprint lithography mold in the same process as the transfer pattern in the same manner as a conventional photomask, it is formed as shown in FIG. 5 or FIG. The upper surface of the mark area 105 (FIG. 5) such as the name mark and the mark structure 106 (FIG. 6) is the same height as the transfer area 102. As a result, when the mold is pressed against the resin on the transfer substrate. In addition, not only the transfer pattern but also the above-mentioned name mark or the like comes into contact with the substrate to be transferred and the resin.

  Here, FIG. 5 shows an example of a mold having the transfer region 102 and the mark region 105 on the upper surface of the same mesa structure, and FIG. 6 shows a mesa structure having the transfer region 102 on the upper surface and the mark structure 106. These show examples of molds formed on the substrate 107, respectively. In FIG. 5B, a pattern is given to explain the range of the transfer area 102 and the mark area 105.

  On the other hand, when a name mark or the like is formed on the surface of the non-transfer area after forming the mesa structure with the transfer area as the upper surface, that is, after digging the non-transfer area inside the mold from the transfer area, the mesa structure Because there is a difference in level, conventional methods such as plate-making on the same plane cannot be used, and a special process needs to be added, which complicates the mold manufacturing process and increases manufacturing costs. .

  The present invention has been made in view of the above circumstances, and solved the problem that the name mark and the like are in contact with the substrate to be transferred and the resin by a simple method without adding a complicated process to the mold production. An object of the present invention is to provide a mold for nanoimprint lithography and a method for manufacturing the same.

  As a result of various studies, the present inventor formed an identification structure constituting a name mark or the like at the same time in an etching process for digging a non-transfer area in order to form a mesa structure having a transfer area as an upper surface. The present invention has been completed by finding that the above problems can be solved by forming a forming etching mask in a specific size corresponding to the height of the mesa structure with the transfer region as the upper surface.

  That is, the present invention is a nanoimprint lithography mold having a mesa structure having a transfer region as an upper surface on a substrate and a non-transfer region around the mesa structure, wherein the non-transfer region has a substantially triangular shape. An identification structure made up of a group of line-shaped or dot-shaped structures having a cross-section is formed, and the height of the identification structure is lower than the height of the mesa structure having the transfer region as an upper surface. A mold for nanoimprint lithography.

  In the invention, it is preferable that the identification structure is formed at a position where the height of the identification structure is lower than a surface connecting the outer edge of the transfer region and the outer edge of the non-transfer region. The mold for nanoimprint lithography.

  Further, the present invention is the mold for nanoimprint lithography, wherein at least a part of the identification structure is a name mark, an ID code, or an alignment mark that recognizes any one of letters, numbers, and symbols. .

The present invention also provides a nanoimprint lithography in which a mesa structure having a transfer region as an upper surface on a substrate and a non-transfer region around the mesa structure, and an identification structure is formed in the non-transfer region. When the short side length W is H, the height of the mesa structure having the transfer region as the upper surface,
0 <W <2 × H
An etching mask having a short side to be an etching mask for forming the identification structure, and a mesa structure having the transfer region as an upper surface by etching the substrate using an isotropic etching solution, A method for producing a mold for nanoimprint lithography, wherein the identification structure having a height lower than the height of the mesa structure is formed in the same step.

In the present invention, the height of the mesa structure with the transfer region as the upper surface is H, the height of the identification structure is h, and the horizontal direction from the outer edge of the transfer region to the outer edge of the non-transfer region is When the distance is L ₁ and the horizontal distance from the apex of the identification structure located on the outermost side from the transfer region to the outer edge of the non-transfer region is L ₂ , the distance L ₂ is
L ₁ × h / H <L ₂ <L ₁
The method for manufacturing a mold for nanoimprint lithography is provided with an etching mask for forming the identification structure so as to satisfy the following relationship.

  According to the mold for nanoimprint lithography of the present invention, since the height of the identification structure constituting the name mark or the like is lower than the height of the mesa structure with the transfer region as the upper surface, the mold is pressed against the resin on the substrate to be transferred. When hitting, not only the transfer pattern but also the name mark and the like can be solved in contact with the substrate to be transferred and the resin.

Further, according to the method for manufacturing a mold for nanoimprint lithography of the present invention, the etching mask for forming the identification structure constituting the name mark or the like and the etching mask for forming the mesa structure with the transfer region as the upper surface are on the same plane. Therefore, the conventional method can be used for making the etching mask, and the manufacturing process of the mold can be prevented from becoming complicated.
Further, since the identification structure constituting the name mark or the like and the mesa structure having the transfer region as the upper surface can be formed in the same process, a name mark or the like is separately formed even when the name mark or the like is formed. Therefore, it is not necessary to increase the number of steps, and the mold can be manufactured with a small number of steps.

It is explanatory drawing which shows the example of the mold for nanoimprint lithography concerning this invention, (a) is a schematic plan view, (b) is AA sectional drawing in (a), (c) is R part in (b). An enlarged view is shown. It is a schematic process drawing which shows the example of the manufacturing method of the mold for nanoimprint lithography concerning this invention. It is a schematic process drawing which shows the example of the manufacturing method of the identification structure which concerns on this invention. It is explanatory drawing which shows the relationship between the identification structure which concerns on this invention, and an etching mask. It is explanatory drawing which shows the example of the mold for the conventional nanoimprint lithography, (a) is a schematic plan view, (b) shows CC sectional drawing in (a). It is explanatory drawing which shows the other example of the conventional mold for nanoimprint lithography, (a) is a schematic plan view, (b) shows DD sectional drawing in (a).

[Mold for nanoimprint lithography]
First, the mold for nanoimprint lithography according to the present invention will be described.
1A and 1B are explanatory views showing an example of a mold for nanoimprint lithography according to the present invention, wherein FIG. 1A is a schematic plan view, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. The enlarged view of the R part in is shown.

  As shown in FIGS. 1A and 1B, a nanoimprint lithography mold 1 according to the present invention has a mesa structure with a transfer region 2 as an upper surface on a substrate 7, and the periphery of the transfer region 2. Includes a non-transfer area 4 through an inclined area 3, and an identification structure 5 constituting a name mark or the like is formed in the non-transfer area 4.

  The identification structure 5 includes a line-shaped or dot-shaped structure 6 having a substantially triangular cross section, and the height of the identification structure 5 is lower than the height of the mesa structure having the transfer region 2 as an upper surface. ing.

  The height of the identification structure 5 described above may be a height that can be identified as a mark or code by an optical method or a physical method, and depends on the height of the mesa structure with the transfer region 2 as an upper surface. For example, it is 3 μm to 30 μm.

  In the mold for nanoimprint lithography of the present invention, the height of the identification structure 5 constituting the name mark or the like is lower than the height of the mesa structure with the transfer region 2 as the upper surface. When pressed against the substrate, it is possible to solve the problem that not only the transfer pattern but also the name mark and the like come into contact with the substrate to be transferred and the resin.

  Further, in the mold for nanoimprint lithography according to the present invention, the identification structure 5 is located at a position where the height of the identification structure 5 is lower than the surface connecting the outer edge of the transfer region 2 and the outer edge of the non-transfer region 4. Preferably it is formed.

Specifically, as shown in FIG. 1C, the height of the mesa structure with the transfer region 2 as the upper surface is H, the height to the apex of the identification structure 5 is h, and the outer edge of the transfer region 2 The horizontal distance from (IE) to the outer edge (OE) of the non-transfer area 4 is L _1, and the position of the non-transfer area 4 from the position of the vertex (ME) of the identification structure 5 located on the outermost side from the transfer area 2 the horizontal distance to the outer edge (OE) in the case of the L _2, the positions of the vertices (ME) of the identified structure 5,
L ₁ × h / H <L ₂ <L ₁
The identification structure 5 is preferably formed so that

  With the configuration as described above, when the mold is pressed against the resin on the transferred substrate, even if the mold is not parallel to the transferred substrate but has an inclination, the identification structure 5 is This is because the problem of contact with the substrate to be transferred and the resin does not occur.

  Next, other elements constituting the mold for nanoimprint lithography according to the present invention will be described.

(substrate)
The substrate 7 can be any substrate that can be used in a mold for nanoimprint lithography. For example, a synthetic quartz substrate used for a photomask can be used, and the size thereof is, for example, 152 mm long, 152 mm wide, and 0.25 inches thick.

(Transcription area)
The size of the transfer region 2 is not particularly limited as long as it is a size used for a mold for nanoimprint lithography. For example, the size is 26 mm in length and 33 mm in width.
The mesa structure having the transfer region 2 as the upper surface is usually formed by forming an etching mask on the substrate 7 and digging up the non-transfer region 4 by wet etching. The height (H) is, for example, 30 μm.

[Method for producing mold for nanoimprint lithography]
Next, a method for producing a nanoimprint lithography mold according to the present invention will be described.

  FIG. 2 is a schematic process diagram showing an example of a method for producing a mold for nanoimprint lithography according to the present invention. In the method for producing a mold for nanoimprint lithography according to the present invention, first, as shown in FIGS. 2A to 2B, an etching mask 8a for forming an identification structure and a transfer region are provided on a top surface of a substrate 7. An etching mask 8b for forming a mesa structure is formed.

  Since the above-described etching mask 8a and etching mask 8b are formed on the same plane, a conventional plate making technique can be used. For example, Cr (chromium) or the like is formed on the substrate 7 as an etching mask layer 8 by sputtering, and a resist is spin-coated thereon, exposed and developed to form a desired resist pattern. The desired etching mask 8a and etching mask 8b can be formed by etching away the exposed sputtered film of Cr or the like.

Here, when the length W of the short side of the etching mask 8a is H, the height of the mesa structure with the transfer region 2 as the upper surface is H.
0 <W <2 × H
It forms so that it becomes.

  Next, the mesa structure having the transfer region 2 as the upper surface and the identification structure 5 are formed in the same process by etching the substrate 7 using an isotropic etching solution such as a hydrofluoric acid aqueous solution ( FIG. 2 (c)).

  After the etching process is completed, the etching mask 8b is removed, and the nanoimprint lithography mold 1 having the mesa structure with the transfer region 2 as the upper surface and the identification structure 5 in the non-transfer region 4 around the transfer region 2 is obtained. Is obtained (FIG. 2 (d)).

  In the present invention, the etching mask 8a for forming the identification structure is formed in the size as described above, thereby increasing the height of the mesa structure having the transfer region 2 as the upper surface and the mesa structure having the transfer region 2 as the upper surface. The identification structure 6 having a height (h) lower than the height (H) can be formed in the same process.

In the present invention, as shown in FIG. 1C, the height of the mesa structure with the transfer region 2 as the upper surface is H, the height of the identification structure 5 is h, and the outer edge of the transfer region 2 ( IE) is a horizontal distance from the outer edge (OE) of the non-transfer area 4 to L _1, and the outer edge (OE) of the non-transfer area 4 from the apex (ME) of the identification structure 5 located on the outermost side from the transfer area 2 ) Is the distance in the horizontal direction to L ₂ , the distance L ₂ is
L ₁ × h / H <L ₂ <L ₁
It is preferable to dispose the etching mask 8a so that

  By providing the etching mask 8a as described above, the height of the identification structure 5 becomes lower than the surface connecting the outer edge of the transfer region 2 and the outer edge of the non-transfer region 4, and the mold is transferred. When pressing against the resin on the substrate, even if the mold is not parallel to the transfer substrate and has an inclination, the problem that the identification structure 5 comes into contact with the transfer substrate and the resin is It does not occur.

Here, the manufacturing method of the identification structure according to the present invention will be described in more detail below.
FIG. 3 is a schematic process diagram showing an example of a method for manufacturing an identification structure according to the present invention. As shown in FIG. 3, when an etching mask 8a having a width W is formed on the substrate 7 (FIG. 3A) and isotropic etching is performed, the portion of the substrate 7 covered with the etching mask 8a is also obtained. Etching progresses with time (FIG. 3B).

When the etching depth H is larger than half the width W of the etching mask 8a, the upper surface of the substrate 7 eventually disappears with the progress of etching, and finally the upper end is sharp. A structure 6 having a substantially triangular cross section is formed (FIG. 3C).
The interval P between the upper ends of the structures 6 is the same as the center interval of the etching mask 8a.

Here, according to the theoretical etching model shown in FIG.
(H−h) ² + (W / 2) ² = H ²
Therefore, the height h of the structure 6 is approximately h = H− {H ² − (W / 2) ² } ^1/2.
Can be expected. However, in reality, the height h of the structure 6 is obtained by experiments.

  As mentioned above, although each embodiment was described about the mold for nanoimprint lithography which concerns on this invention, and its manufacturing method, this invention is not limited to the said embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration and exhibits the same function and effect regardless of the case. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
A synthetic quartz substrate having a length of 152 mm, a width of 152 mm, and a thickness of 0.25 inch was used as the substrate 7. A Cr film having a thickness of 0.05 μm was formed on one main surface of the synthetic quartz substrate by sputtering. An etching mask 8a for forming an identification structure and an etching mask 8b for forming a mesa structure having the transfer region 2 as an upper surface were formed by the same photolithography plate making.

Here, the etching mask 8a is a line-and-space pattern in which a group of 50 lines having a width W of 55 μm in the horizontal direction and a length of 10 mm in the vertical direction is arranged at an interval of 110 μm. When the coordinates are (0, 0), the XY coordinates of the center of the etching mask 8a are arranged to be (−36.5, 0) in mm units.
On the other hand, the etching mask 8b was a rectangular pattern with a length of 26 mm and a width of 33 mm, and the center of the etching mask 8 b was arranged so as to coincide with the center of the substrate 7.

Next, the substrate 7 is etched using an aqueous hydrofluoric acid solution. After the etching process is completed, the etching mask 8b is removed, so that the mesa structure having the transfer region 2 as the upper surface and the identification structure 5 are the same. Formed in the process.
Here, the etching depth, that is, the height (H) of the mesa structure having the transfer region 2 as the upper surface was set to 30 μm.

  The obtained identification structure 5 is a line-and-space pattern in which 50 structures 6 having a substantially triangular cross section with a sharp top end having a height (h) of approximately 18 μm are arranged at intervals of 110 μm. The entire identification structure 5 (generally a rectangle having a length of 10 mm and a width of 5.5 mm) could be identified visually.

  In the obtained mold for nanoimprint lithography, when the transfer region 2 on the upper surface of the mesa structure is pressed against the resin on the transfer substrate, the identification structure 5 comes into contact with the transfer substrate or the resin. The phenomenon did not occur.

DESCRIPTION OF SYMBOLS 1 ... Mold for nanoimprint lithography 2 ... Transfer area 3 ... Inclined area 4 ... Non-transfer area 5 ... Identification structure 6 ... Line-shaped structure 7 ... Substrate 8 ... Etching mask layer 8a, 8b ... Etching mask 101 ... Nanoimprint lithography mold 102 ... Transfer area 103 ... Inclined area 104 ... Non-transfer area 105 ... Mark area 106 ... Mark Structure 107 ... Substrate IE ... Outer edge of transfer area OE ... Outer edge of non-transfer area MP ... Apex of cross section of structure

Claims (5)

A method for producing a mold for nanoimprint lithography, comprising: a mesa structure having a transfer region as an upper surface on a substrate; and a non-transfer region around the mesa structure, wherein an identification structure is formed in the non-transfer region. There,
Forming the mesa structure having the transfer region as an upper surface and the identification structure having a height lower than the height of the mesa structure in the same step;
The structure constituting the identification structure is formed by performing etching so that wet etching proceeds from both sides of the pattern of the etching mask and all the upper surfaces of the substrate in the etching mask disappear in plan view. A method for producing a mold for nanoimprint lithography. A nanoimprint lithography mold having a mesa structure with a transfer region as an upper surface on a substrate and a non-transfer region around the mesa structure,
In the non-transfer area, an identification structure composed of a line-shaped or dot-shaped structure is formed, and the height of the identification structure is lower than the height of the mesa structure having the transfer area as an upper surface. And
The structure constituting the identification structure is formed by etching so that wet etching proceeds from both sides of the pattern of the etching mask and all the upper surfaces of the substrate in the etching mask disappear in plan view. A mold for nanoimprint lithography, characterized by A nanoimprint lithography mold having a mesa structure with a transfer region as an upper surface on a substrate and a non-transfer region around the mesa structure,
In the non-transfer area, an identification structure composed of a line-shaped or dot-shaped structure is formed, and the height of the identification structure is lower than the height of the mesa structure having the transfer area as an upper surface. And
The mold for nanoimprint lithography, wherein the structure constituting the identification structure has a cross section having inclined surfaces formed so as to spread toward both ends.   The mold for nanoimprint lithography according to claim 2, wherein the identification structure has a region surrounded by a top of the structure.   The mold for nanoimprint lithography according to any one of claims 2 to 4, wherein the identification structure is an alignment mark.

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