JP2009105252A - Manufacturing method for fine pattern, and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a large-area fine pattern inexpensively in high throughput. <P>SOLUTION: The manufacturing method for the fine pattern includes: a patterned resist layer forming stage of forming a layer 2 to be processed on a transparent base 1, forming a resist layer of a transparent dielectric on the layer 2 to be processed, and patterning the resist layer by a nanoimprinting method to form a patterned resist layer 3 having a recessed portion 53 on a top surface of the resist layer; and an etching stage of forming a hard mask layer 4 of a metal layer on a top surface 3a of the patterned resist layer 3, etching away resist residues 55 left at a bottom portion 53a of the recessed portion 53a, and then etching the layer 2 by using the patterned resist layer 3 as a mask. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fine pattern manufacturing method and an optical element.

  In recent years, semiconductor elements or optical elements having fine patterns that require nano-order processing accuracy are increasing. Semiconductor devices are required to have finer wiring and pattern sizes in order to increase the degree of integration, and in optical devices, in order to control light with higher accuracy. However, as the fine pattern becomes thinner, the production of the fine pattern becomes more difficult and the production cost becomes higher.

  As a representative method for producing such a fine pattern, a combination of lithography and dry etching is generally used. In this method, an etching target film and a resist are sequentially formed on a substrate, and the resist is patterned using an electron beam (EB) lithography or an optical lithography (for example, ArF excimer laser lithography) to form an etching mask. The exposed portion of the etching target film is dry-etched and finally the resist is removed to transfer the fine pattern to the etching target film. According to this method, a complicated wiring pattern or the like can be accurately and precisely formed on the etching target film. For example, a fine metal pattern having a width of several tens of nanometers can be produced.

  Patent Documents 1 to 9 disclose examples in which a fine pattern is manufactured using this method. Patent Document 1 discloses a method for manufacturing a grid polarizer. In this manufacturing method, a metal film is formed on a substrate, a photoresist patterned in a striped pattern is formed thereon, a hard coating of metal or dielectric is further obliquely deposited thereon, and the hard coating is masked. Then, after the metal film is dry-etched to form a metal grid, the mask is removed to manufacture a grid polarizer.

  In addition, a grid polarizer (Grid Polarizers (GP)), in particular, a wire grid polarizer (Wire-Grid Polarizers (WGP)), is a grid of conductor thin wires (conductor grids) with a period equal to or less than the wavelength of the target light. Arranged in parallel to each other. When light is incident on the grid polarizer, part of the electric field component of the light oscillating in a direction parallel to the conductor grid is reflected by the grid polarizer and oscillates in a direction perpendicular to the conductor grid. Since the electric field component of light has the property of transmitting through this grid polarizer, only a polarized component of the target light can pass through.

  Patent Document 2 discloses a method for manufacturing a semiconductor element. In this manufacturing method, a fine gate electrode pattern can be easily formed. Here, a method of oblique deposition of a patterned resist and a metal film is used. In addition to using this oblique deposition technique, the resist is used like a wall or “eave” to form a portion where the metal film is deposited and a portion where the metal film is not deposited, thereby making the fine pattern finer. Form.

  Patent Document 3 discloses a compound semiconductor device and a method for manufacturing the compound semiconductor device. After patterning a resist, a method of oblique deposition of a metal film is used. Patent Document 4 discloses a method for manufacturing a field emission cold cathode. After forming a resist and patterning the resist to form an opening, a metal is obliquely deposited on the opening, thereby forming an opening in the opening. Forming an emitter. Patent Document 5 discloses a method for manufacturing a semiconductor device. Al is obliquely deposited on the spacer film to form a metal film. The spacer film is provided with a recess portion formed of a recess, and the metal film formed by oblique deposition is not formed on the bottom surface of the recess portion. Therefore, by etching using the metal film as a mask, the bottom surface of the recess portion is etched, the metal film is removed, and a gate electrode is formed on the bottom surface of the recess portion, thereby forming a fine pattern.

  Patent Document 6 discloses a method for manufacturing an optical element having a fine structure. Conventionally, the cross section of a resist that forms a fine pattern has been limited to a rectangular shape, but by forming a metal film on the side wall surface of the resist, a fine pattern can be formed even if the cross section of the resist has a wave shape. It is described that it can be formed. Patent Document 7 discloses a nanometer-order mechanical vibrator, a manufacturing method thereof, and a measuring apparatus using the mechanical vibrator. Patent Document 8 creates a patterned media imprint master. An apparatus, method and system are disclosed. Both documents describe the production of a metal film by oblique vapor deposition. Patent Document 9 discloses a method for forming a gate electrode. It describes a method for forming a fine pattern gate electrode by using a patterned resist and an oblique deposition technique.

However, in any of the above-described fine pattern manufacturing methods, low-throughput, small-area, high-cost electron beam (EB) lithography or optical lithography (for example, ArF excimer laser lithography) is required for resist patterning. There is a problem that it is not suitable for manufacturing a device manufactured with high throughput and large area.
JP-A-9-304620 JP-A-8-250513 JP 11-186292 A JP 2000-173448 A JP 2002-26034 A JP 2006-11129 A JP 2006-153886 A JP 2006-286181 A JP-A-3-87036

  The present invention has been made in view of the above problems, and an object thereof is to provide a method for manufacturing a fine pattern with high throughput, large area, and low cost.

  The fine pattern manufacturing method of the present invention includes forming a processing target layer on a transparent substrate, forming a resist layer made of a transparent dielectric on the processing target layer, and patterning the resist layer by a nanoimprint method. A patterned resist layer forming step of forming a patterned resist layer having a recess on the upper surface of the resist layer, and forming a hard mask layer made of a metal layer on at least the upper surface of the patterned resist layer; And etching the remaining resist residue by etching, and then etching the processing target layer using the patterned resist layer as a mask.

  The fine pattern manufacturing method of the present invention includes a step of removing the hard mask layer and the patterned resist layer after the etching step.

  The fine pattern manufacturing method of the present invention is characterized in that the processing target layer is made of a metal layer.

  In the fine pattern manufacturing method of the present invention, the etching step is a step of sequentially etching the resist residue, a natural oxide film formed on the processing target layer made of a metal layer, and the processing target layer. It is characterized by that.

In the fine pattern manufacturing method of the present invention, in the etching step, any one of O ₂ , CF ₄ , CHF ₃ , Ar, HCl, Cl ₂ , BCl ₃ , H ₂ , and N ₂ is used as an etching gas for the resist residue. A gas containing any of CF ₄ , CHF ₃ , Ar, HCl, Cl ₂ , BCl ₃ , H ₂ , and N ₂ is used as an etching gas for the natural oxide film. Dry etching is performed using a gas containing any of CF ₄ , CHF ₃ , Ar, Cl ₂ , and N ₂ as an etching gas, a gas pressure of 0.1 to 10 Pa, and a bias power of 10 to 2000 W. It is characterized by.

  The fine pattern manufacturing method of the present invention is characterized in that, in the etching step, the hard mask layer is formed on the upper surface of the resist layer by vapor deposition, and then the processing target layer is etched.

  The fine pattern manufacturing method of the present invention is characterized in that, in the etching step, the hard mask layer is formed on the upper surface of the resist layer by oblique vapor deposition, and then the processing target layer is etched.

  In the fine pattern manufacturing method of the present invention, in the etching step, the hard mask layer is formed by sputtering so that the thickness of the upper surface of the resist layer is thicker than the thickness of the bottom of the concave portion, and then wet etching is performed. And removing only the hard mask layer in the recess, forming the hard mask layer on the upper surface of the resist layer, and then etching the processing target layer.

  The fine pattern manufacturing method of the present invention uses a ashing method or a polishing method after applying a hard mask material by a wet coating method so as to cover the surface of the patterned resist layer having the recesses in the etching step. After exposing the upper surface of the patterned resist layer and using the hard mask material left in the recess as the hard mask layer, the exposed portion of the patterned resist layer is etched away, and then the remaining portion of the patterned resist layer The processing target layer is etched by using as a mask.

  In the optical element of the present invention, a fine pattern formed in a grid shape is formed on a transparent substrate, and the fine pattern is formed of a metal layer, a transparent dielectric layer laminated on the metal layer, It consists of another metal layer formed on the said transparent dielectric material layer, It is characterized by the above-mentioned.

  The optical element of the present invention is characterized in that the transparent dielectric layer has a height of 200 nm or more.

  According to the method for producing a fine pattern of the present invention, a method for producing a fine pattern having a high throughput, a large area, and a low cost can be provided.

(Embodiment 1)
An example of a fine pattern manufacturing method according to an embodiment of the present invention will be described.
1A to 1D and 2A to 2D are process cross-sectional views illustrating an example of a fine pattern manufacturing method according to an embodiment of the present invention.

  The fine pattern manufacturing method according to the embodiment of the present invention includes a patterned resist layer forming step and an etching step.

(Pattern resist layer formation process)
After the upper surface 1a of the transparent substrate 1 as shown in FIG. 1A is cleaned by a known cleaning method, the processing target layer 2 is formed with a film thickness t as shown in FIG. 1B.

The processing target layer 2 is preferably made of a metal layer. This is because a fine pattern can be formed accurately and the shape stability is high.
When a metal material is used as the material of the processing target layer 2, a metal material such as Al, Au, or Ag may be used alone, or may be configured as an alloy composed of a plurality of types of metals. It is good also as a structure which consists of a metal layer. For example, in the case of forming a grid polarizer, the extinction ratio (contrast) can be increased if the processing target layer 2 is made of Al and a fine pattern is formed.

  When the processing target layer 2 is made of a metal layer, a natural oxide layer may be formed on the surface thereof. When the processing target layer 2 is formed as a metal layer, a natural oxide layer may be formed on the surface of the metal layer depending on the manufacturing process conditions. In this case, since the film thickness of the natural oxide layer is very thin, it hardly affects the characteristics of the grid polarizer.

As the material of the processing target layer 2, a non-metallic material may be used. This is because a fine pattern made of a non-metallic material can also be used for an optical element or the like. When a non-metallic material is used as the material of the processing target layer 2, for example, a metal oxide such as Al ₂ O ₃ can be used.

  As a forming method of the processing target layer 2, in addition to a dry process such as a vapor deposition method and a sputtering method, a wet process such as a spin coating method and a dip method can be appropriately selected and used.

Further, the base layer 40 may be formed between the processing target layer 2 and the transparent substrate 1 by forming another material as necessary.
The underlayer 40 is provided to increase the adhesion between the transparent substrate 1 and the processing target layer 2 or to use a two-layer structure including the processing target layer 2 and the underlayer 40 as a structure for forming a fine pattern. be able to.
As a material of the underlayer 40, a resin material or the like can be used in addition to the metal material or the non-metal material mentioned as the material of the processing target layer 2.

  Next, as illustrated in FIG. 1C, a resist layer 48 made of a transparent dielectric is applied on the processing target layer 2 with a film thickness v. Further, the fine pattern is transferred to the resist layer 48 using the nanoimprint method. Specifically, a mold 46 in which a fine pattern composed of concave portions 44 having a width W and a pitch p is pressed on the surface 46a, and the shape is transferred (patterned) to the resist layer 48. Thereby, as shown in FIG.1 (d), the patterned resist layer 3 which has the fine pattern which consists of the recessed part 53 of width p-W and the pitch p is formed in the upper surface 3a.

  The transfer process can be completed in a few minutes, and a large number of parts having the same shape can be produced in a short time. Further, the unevenness of the fine pattern of the mold 46 used in the nanoimprint method is formed in the range of several tens of nm to several hundreds of nm, and is usually created using an electron beam (EB) exposure technique and an etching technique.

  The resist layer 48 is not particularly limited as long as it has a certain level of etching resistance (at least equal to or slower than the etching rate of the processing target layer 2) when the processing target layer 2 is etched. From the viewpoint of performing nanoimprinting with higher throughput, it is desirable to use a radical polymerization resist, for example, PAK-01 manufactured by Toyo Gosei Kogyo.

  However, in this nanoimprint method, the mold is pressed against the resist layer 48 to transfer the shape, so that the resist residue 55 consisting of the extra resist layer 48 is inevitably left on the bottom surface 53 a of the recess 53. The resist residue 55 can be removed by etching back by anisotropic etching. However, since the wraparound inevitably occurs during the etch back, the etch back cannot be performed completely perpendicular to the substrate surface 1a. There is a possibility that the outer shape of the fine pattern is scraped off by this etch back. In the case of a fine pattern composed of unevenness in the range of several tens of nm to several hundreds of nm, the effect of this cutting is large and becomes a big problem. Therefore, in the next etching step, first, the hard mask layer 4 is formed, and then etching is performed using this as a mask.

(Etching process)
First, as shown in FIG. 2A, a hard mask layer 4 made of a metal layer is formed on the upper surface 3a of the patterned resist layer 3 with a film thickness x.

  The material of the hard mask layer 4 is preferably a material having high etching resistance, and for example, a metal material such as Ni or Cr can be used. For example, Ni is a material having high etching resistance and can be effectively used as a mask in all etching processes.

  When the metal material is used as the hard mask layer 4, it can be formed by a vapor deposition method. In this case, a vapor deposition mask in which holes corresponding to the protrusions 50 are laid out and arranged is arranged on the upper surface 3a of the patterned resist layer 3 precisely, and then the metal material is vapor-deposited to form a hard mask layer. 4 is formed.

  Note that a vapor deposition mask is not necessarily used in the vapor deposition step. Since the width p-W and the depth s of the recess 53 are formed in the range of several tens of nm to several hundreds of nm, and the depth s is set larger than the width p-W, the patterned resist layer When the hard mask layer 4 is formed on the upper surface 3a of the hard disk 3, the hard mask layer 4 is difficult to enter the recess 53, and the hard mask layer 4 having a desired thickness is formed while the hard mask layer 4 is formed. Even if the mask layer 4 penetrates, the concave portion 53 can be prevented from being completely filled with the hard mask layer 4.

  At this time, although these dimensions depend on the film forming method of the hard mask layer 4 and the required film forming thickness, the width pW of the recess 53 is preferably as narrow as possible and the depth s is as deep as possible. Further, when the width pW and the depth s of the concave portion 53 are in the range of several tens of nanometers to several hundreds of nanometers, it is not determined only by the ratio of the opening size of the concave portion 53 to the metal particle diameter, and the opening is sufficiently large with respect to the particle size. However, the metal particles hardly enter the bottom 53a of the recess 53.

Next, as shown in FIG. 2B, anisotropic etching is performed as indicated by an arrow r in a direction substantially perpendicular to the upper surface 1a of the transparent substrate 1 from the hard mask layer 4 side.
This anisotropic etching is performed in two stages. First, the resist residue 55 left on the bottom 53a of the recess 53 is removed by etching by the first anisotropic etching. Further, in the next anisotropic etching, the remaining layer of the patterned resist layer 3 that has not been etched away by the first anisotropic etching is used as an etching mask, and the processing target layer exposed by removing the resist residue 55 2 is removed by dry etching.

In the etching process, the etching conditions are as follows.
First, in etching the resist residue 55, it is preferable to use a gas containing any of O ₂ , CF ₄ , CHF ₃ , Ar, HCl, Cl ₂ , BCl ₃ , H ₂ , and N ₂ as an etching gas. Basically, any etching gas can be used for etching, but O ₂ is particularly preferable for organic substances such as resist. The etching gas may be used alone or as a mixed gas.

  The flow rate of the etching gas varies depending on the apparatus, but is preferably about 1 to 500 sccm (cc / min).

  The gas pressure of the etching gas is preferably 0.1 to 10 Pa. In general, the higher the gas pressure is, the higher the etching rate can be. However, since the anisotropy is lost because the interaction between molecules and radicals becomes intense, it is not preferable to set the gas pressure higher than 10 Pa. On the other hand, when the gas pressure is lower than 0.1 Pa, it is difficult to generate plasma, which is not preferable. In the present invention, since extreme anisotropy is required, the gas pressure is preferably low, and particularly preferably 1 Pa or less in view of stable plasma discharge.

  The bias power is preferably 10 to 2000 W. The larger the value, the higher the anisotropy of molecules and radicals and the higher the etching rate.

In the etching of the processing target layer 2, the etching conditions are different between the case where a metal layer is used as the processing target layer 2 and the case where a non-metal layer is used.
When a metal layer is used as the processing target layer 2, it is preferable to use a gas containing any of CF ₄ , CHF ₃ , BCl ₃ , Ar, Cl ₂ , and N ₂ as an etching gas. The etching gas may be used alone or as a mixed gas.

When a non-metal layer is used as the processing target layer 2, a gas containing any of CF ₄ , CHF ₃ , Ar, HCl, Cl ₂ , BCl ₃ , H ₂ , and N ₂ is used as an etching gas. It is preferable. The etching gas may be used alone or as a mixed gas.

When the processing target layer 2 is made of a metal layer and a natural oxide layer is formed on the surface thereof, the etching step includes the resist residue 55, the natural oxide layer, and the metal layer. A step of sequentially etching is used. Thus, by sequentially etching, the fine pattern formed on the resist layer 48 by the nanoimprint method can be accurately transferred to the processing target layer 2.
For example, when a metal layer made of aluminum (Al) is used as the processing target layer 2 and a natural oxide layer made of Al ₂ O ₃ is formed on the surface thereof, first, BCl ₃ that is a reducing etching gas is used. Preferably, the native oxide layer made of Al ₂ O ₃ is etched using H ₂ , N ₂ or the like, and then the metal layer made of Al is etched using Cl ₂ or the like.

In the etching of the processing target layer 2, the flow rate of the etching gas is preferably 1 to 500 sccm (cc / min). The gas pressure of the etching gas is preferably 0.1 to 10 Pa. Furthermore, the bias power is preferably 10 to 2000 W. The reason is the same as in the case of resist etching.
By performing etching under these conditions, a precise fine pattern can be efficiently produced.

  By performing this etching step, the resist residue 55 can be surely removed by the etching step, and the portion masked by the hard mask layer 4 provided on the upper surface 3a of the patterned resist layer 3 is reliably left. Can be made.

The fine pattern 13 shown in FIG. 2C is a schematic cross-sectional view showing an example of the fine pattern manufactured in this way.
The structure 70 of the fine pattern 13 is formed as a structure having a width W and a height l, and has a three-layer structure including a processing target layer 2, a patterned resist layer 3, and a hard mask layer 4 made of a metal layer. It is said that. The structures 70 are arranged at intervals pW and pitch p.

  When this fine pattern 13 is used as a grid polarizer, it is preferable that the period p is 100 nm or less and the height l is 200 nm or more. This is because the extinction ratio can be increased by doing so. When the width W is 50 nm, the aspect ratio (height 1 / width W) is 4. The higher the aspect ratio, the higher the extinction ratio (contrast), but the manufacturing becomes difficult.

  The fine pattern 13 has a three-layer structure of a processing target layer 2, a patterned resist layer 3 made of a transparent dielectric, and a hard mask layer 4 made of a metal layer. The patterned resist layer 3 is light transmissive. Therefore, the extinction ratio (contrast) can be improved while keeping the transmittance high.

In the anisotropic etching step, the transparent substrate 1 may be etched as necessary. In that case, the height l of the structure 70 of the fine pattern 13 can be increased, and the extinction ratio (contrast) can be increased.
Further, when the base layer 40 is formed between the transparent substrate 1 and the processing target layer 2, the base layer 40 may be removed by etching as necessary. Also in this case, the height l of the fine pattern structure 70 can be increased, and the extinction ratio (contrast) can be increased.

Furthermore, after the anisotropic etching step, a step of removing the hard mask layer 4 and the patterned resist layer 3 by immersing in a resist removing solution may be performed.
A fine pattern 10 shown in FIG. 2D is a schematic cross-sectional view showing another example of a fine pattern manufactured by removing the hard mask layer 4 and the patterned resist layer 3.
The fine pattern 10 is formed by arranging the processing target layers 2 having a width W and a height t at intervals p-W and a pitch p.

  In this way, the fine patterns 13 and 10 can be manufactured. These fine patterns 13 and 10 can be used for optical elements or semiconductor elements, for example.

  The method for manufacturing a fine pattern according to the embodiment of the present invention is a nine-imprint method, that is, by pressing a mold 46 having a fine pattern having a recess 44 in the range of several tens to several hundreds of nanometers against a resist layer 48. Since the fine pattern of the mold 46 is transferred to the resist layer 48, the fine patterns 13 and 10 can be formed at a low cost and with a high throughput. Moreover, by making the large-area mold 46, the large-area fine patterns 13 and 10 can be easily formed.

  The fine pattern manufacturing method according to the embodiment of the present invention is configured to perform anisotropic etching by protecting a portion not to be etched with the hard mask layer 4, so that it remains in the concave portion 53 of the fine pattern 10 formed by the nine printing method. Only the resist residue 55 thus formed can be easily removed, and the fine patterns 13 and 10 can be formed efficiently. Further, it is not necessary to consider the thickness of the resist residue 55 and the material of the etching target.

  Since the fine pattern manufacturing method according to the embodiment of the present invention is configured to perform anisotropic etching by protecting a portion not to be etched with the hard mask layer 4, even if the patterned resist layer 3 itself has no etching resistance, it is easy. Fine patterns 13 and 10 can be manufactured. Conversely, even when the processing target layer 2 is resistant to etching, the fine patterns 13 and 10 can be efficiently manufactured.

(Embodiment 2)
Another example of the fine pattern manufacturing method according to the embodiment of the present invention will be described.
3A to 3D are process cross-sectional views illustrating another example of the method for manufacturing a fine pattern according to the embodiment of the present invention.
The fine pattern manufacturing method according to the embodiment of the present invention includes a patterned resist layer forming step and an etching step as in the first embodiment. In the etching step, the hard mask layer 4 is formed by an oblique deposition method. This is different from the fine pattern manufacturing method shown in the first embodiment. In addition, the same code | symbol is attached | subjected and shown about the member similar to the member used in Embodiment 1. FIG.

(Pattern resist layer formation process)
Similar to the process shown in the first embodiment, the patterned resist layer forming process is performed to form the processing target layer 2 on the transparent substrate 1, and the patterned resist layer 3 is further formed.

(Etching process)
Next, in this etching step, first, the hard mask layer 4 is formed and then etched using this as a mask. FIG. 3A is a diagram illustrating an example of a process cross-sectional view at the time when the patterned resist layer 3 is formed. A patterned resist layer in which a processing target layer 2 is formed on the transparent substrate 1 with a thickness t, and further, recesses 53 having a width pW and a depth s are formed on the processing target layer 2 at a pitch p. 3 is formed.
The direction of the vapor deposition material flying from the vapor deposition source is indicated by an arrow q. The arrow q is a direction that forms an angle θ (deposition angle) from a line m perpendicular to the substrate surface 1 a of the transparent substrate 1.

By performing the oblique deposition method at such a deposition angle θ, the hard mask layer 4 is formed on the upper surface 3a of the patterned resist layer 3 as shown in FIG.
That is, when the oblique deposition method is used, in the concave portion 53, in the initial stage of vapor deposition, the patterned resist layer 3 protruding adjacently serves as a mask, and the entry path is obstructed, so that the bottom 53a of the concave portion 53 Vapor deposition components hardly penetrate. Therefore, the hard mask layer 4 is not formed on the bottom 53a of the recess 53 and the surface 53c opposite to the vapor deposition source.
On the other hand, the hard mask layer 4 is sequentially laminated only on the upper surface 3 a of the patterned resist layer 3 and the surface 53 b of the recess 53 on the vapor deposition source side. After the hard mask layer 4 starts to grow on the upper surface 3a of the patterned resist layer 3, the entry path is blocked by the hard mask layer 4, so that the vapor deposition component is mainly laminated on the hard mask layer 4 and vapor deposition. The hard mask layer 4 facing in the direction is grown, and the vapor deposition component is less likely to enter the recess 53.
In this manner, as shown in FIG. 3B, the layers grow in the upward direction in the figure and are stacked while gradually increasing the lamination range in the lateral direction in the figure.

  The vapor deposition angle θ is preferably 45 ° or more. In order to improve the film quality of the hard mask layer 4 and the adhesion of the hard mask layer 4 to the upper surface 3a of the patterned resist layer 3, the deposition angle θ is preferably in the range close to 0 °. In order not to form the hard mask layer 4 on 53a, the deposition angle θ is preferably set to 45 ° or more in consideration that the deposition angle θ should be large. Although depending on the size and shape of the fine pattern, in the case of forming a general fine pattern, the hard mask layer 4 is not formed on the bottom surface 53a of the recess 53 if the deposition angle θ is set to 45 ° or more. This is to help. For example, when the width pW of the recess 53 is equal to the depth s, that is, when s = pW, or when the depth s of the recess 53 is greater than the width pW, that is, s> In the case of p-W, the hard mask layer 4 is not formed on the bottom surface 53a of the recess 53 if at least the angle θ = 45 °.

  In this way, when the oblique vapor deposition method is used, the hard mask layer 4 can be formed on the upper surface 3a of the patterned resist layer 3 without using a vapor deposition mask. Therefore, it is not necessary to align the vapor deposition mask, and the production efficiency of the fine pattern can be improved.

In order to form the hard mask layer 4 in close contact with the upper surface 3a of the patterned resist layer 3 in the oblique deposition method, it is preferable to set the substrate temperature appropriately. When the substrate temperature is too low, good adhesion strength cannot be obtained, and when the substrate temperature is too high, a stable columnar shape cannot be obtained.
For example, it is preferably 30% to 50% of the melting point of the hard mask layer 4 measured in absolute temperature. That is, when the hard mask layer 4 is Al, since the melting point is 933 K (660 ° C.), the preferable temperature range is preferably 280 K to 466 K (7 ° C. to 193 ° C.).

Next, as shown in FIG. 3C, anisotropic etching is performed as indicated by an arrow r in a direction substantially perpendicular to the surface 1a of the transparent substrate 1 from the hard mask layer 4 side.
First, the resist residue 55 left in the recess 53 is removed by etching by the first anisotropic etching.
Further, in the next anisotropic etching, using the hard mask layer 4 and the patterned resist layer 3 as an etching mask, the processing target layer 2 exposed by removing the resist residue 55 is removed by dry etching, and FIG. As shown in (d), the surface 1a of the transparent substrate 1 is exposed.
On the other hand, the hard mask layer 4 serves as a mask, the patterned resist layer 3 masked by the hard mask layer 4 is not etched, and the processing target layer 2 masked by the patterned resist layer 3 is not etched. As a result, a fine pattern 15 composed of the processing target layer 2, the patterned resist layer 3, and the hard mask layer 4 is formed.

The fine pattern 15 shown in FIG. 3D is a schematic cross-sectional view showing an example of the fine pattern manufactured in this way.
The structure 70 of the fine pattern 15 is formed as a structure having a width W and a height l, and includes a processing target layer 2, a patterned resist layer 3 made of a transparent dielectric, and a hard mask made of another metal layer. A three-layer structure with the layer 4 is adopted. The structures 70 are arranged at intervals pW and pitch p.

  Note that a step of removing the hard mask layer 4 and the patterned resist layer 3 by immersing in a resist removing solution after the etching step may be performed. By performing this process, as shown in FIG. 2D of Embodiment 1, a fine pattern 10 in which the processing target layer 2 is formed on the surface 1a of the transparent substrate 1 can be formed.

  The fine pattern manufacturing method according to the embodiment of the present invention is a configuration in which the hard mask layer 4 is formed using an oblique vapor deposition method in the hard mask layer forming step. The production efficiency of 15, 10 can be improved and the production cost can be reduced.

(Embodiment 3)
Another example of the fine pattern manufacturing method according to the embodiment of the present invention will be described.
4A to 4C are process cross-sectional views illustrating still another example of the fine pattern manufacturing method according to the embodiment of the present invention.

  The fine pattern manufacturing method according to the embodiment of the present invention includes a patterned resist layer forming step and an etching step, as in the first embodiment. In the etching step, the patterned resist layer 3 is formed by sputtering. After the hard mask layer 42 is formed so that the film thickness h of the hard mask layer 42b formed on the upper surface 3a is larger than the film thickness i of the hard mask layer 42a formed on the bottom 53a of the recess 53, wet etching is performed. This is different from the fine pattern manufacturing method shown in the first embodiment in that only the hard mask layer 42a of the recess 53 is removed and the hard mask layer 4 is left only on the upper surface 3a of the patterned resist layer 3. In addition, the same code | symbol is attached | subjected and shown about the member similar to the member used in Embodiment 1. FIG.

(Pattern resist layer formation process)
Similar to the process shown in the first embodiment, the patterned resist layer forming process is performed to form the processing target layer 2 on the transparent substrate 1, and the patterned resist layer 3 is further formed.

(Etching process)
In the etching step, first, the hard mask layer 4 is formed and then etched using this as a mask. 4A shows that the film thickness h of the hard mask layer 42b formed on the upper surface 3a of the patterned resist layer 3 is greater than the film thickness i of the hard mask layer 42a formed on the bottom 53a of the recess 53 by sputtering. It is a figure which shows an example of process sectional drawing at the time of forming the hard mask layer 42 so that it may become thick. As described above, the hard mask layer 42 includes the hard mask layer 42 b formed on the upper surface 3 a of the patterned resist layer 3 and the hard mask layer 42 a formed on the bottom 53 a of the recess 53.

  Since the width p-W and the depth s of the recess 53 are in the range of several tens of nanometers to several hundreds of nanometers and the depth s is set larger than the width p-W, the patterned resist layer 3 When the hard mask layer 42 is formed on the upper surface 3a of the substrate, the hard mask layer 42a is less likely to enter the recess 53, and the hard mask layer 42b having a desired thickness is formed on the upper surface 3a of the patterned resist layer 3. In addition, even if the hard mask layer 42a enters the recess 53, the recess 53 can be prevented from being filled with the hard mask layer 42a.

  Next, wet etching is performed in which the hard mask layer 42 is removed by etching at a uniform depth. For example, if the depth is i, the hard mask layer 42a of the concave portion 53 is completely removed, and the hard mask layer 4 having a height hi is left on the tip side 50b of the convex portion 50. In this way, only the hard mask layer 42a of the recess 53 is removed, and the hard mask layer 42 is left only on the upper surface 3a of the patterned resist layer 3, and this is removed as shown in FIG. Layer 4 is assumed.

Next, anisotropic etching is performed in a direction substantially perpendicular to the surface 1a of the transparent substrate 1 from the hard mask layer 4 side.
First, by the first anisotropic etching, the resist residue 55 left on the bottom 53a of the recess 53 is removed by etching.
Furthermore, in the next anisotropic etching, using the patterned resist layer 3 masked by the hard mask layer 4 as an etching mask, the processing target layer 2 exposed by removing the resist residue 55 is removed by dry etching. As shown in FIG. 4C, the surface 1a of the transparent substrate 1 is exposed.
On the other hand, the hard mask layer 4 serves as a mask, the patterned resist layer 3 masked by the hard mask layer 4 is not etched, and the processing target layer 2 masked by the patterned resist layer 3 is not etched. As a result, a fine pattern 17 composed of the processing target layer 2, the patterned resist layer 3, and the hard mask layer 4 is formed.

  Note that a step of removing the hard mask layer 4 and the patterned resist layer 3 by immersing in a resist removing solution after the etching step may be performed. By performing this process, as shown in FIG. 2D of Embodiment 1, a fine pattern 10 in which the processing target layer 2 is formed on the surface 1a of the transparent substrate 1 can be formed.

  In the fine pattern manufacturing method according to the embodiment of the present invention, after forming the hard mask layer 42 by sputtering, a part of the hard mask layer 42b formed on the upper surface 3a of the patterned resist layer 3 is formed by wet etching. The hard mask layer 42a formed on the bottom surface 53a of the concave portion 53 is completely removed, so that the hard mask layer 4 can be easily formed and the manufacturing efficiency of the fine patterns 17 and 10 can be improved. Production costs can be reduced.

(Embodiment 4)
Another example of the fine pattern manufacturing method according to the embodiment of the present invention will be described.
5A to 5D are process cross-sectional views illustrating still another example of the fine pattern manufacturing method according to the embodiment of the present invention.

  The fine pattern manufacturing method according to the embodiment of the present invention includes a patterned resist layer forming step and an etching step, as in the first embodiment, and the etching step is performed by the wet coating method. After the hard mask material 40 is applied so as to cover the surface, the upper surface 3a of the patterned resist layer 3 is exposed using an ashing method or a polishing method, and the hard mask material 40 left in the concave portion 53 is replaced with the hard mask layer 4. This is different from the method for manufacturing a fine pattern shown in the first embodiment in that it is a process to be performed. In addition, the same code | symbol is attached | subjected and shown about the member similar to the member used in Embodiment 1. FIG.

(Pattern resist layer formation process)
Similar to the process shown in the first embodiment, a patterned resist layer forming step is performed to form the processing target layer 2 on the transparent substrate 1, and further, the patterned resist layer 3 is formed on the processing target layer 2. .

(Etching process)
Next, as shown in FIG. 5A, a hard mask material 40 is applied on the patterned resist layer 3 so as to cover the surface of the patterned resist layer 3 by wet coating.
Here, the hard mask material 4 is deposited so that the thickness u of the hard mask material 40 is thicker than the depth s of the recess 53.

  Next, as shown in FIG. 5B, the surface side 40b of the hard mask material 40 is removed by using an ashing method or a polishing method until the upper surface 3a of the patterned resist layer 3 is exposed, and the recess 53 The hard mask material 40 left in the step is used as the hard mask layer 4.

Next, as shown in FIG. 5C, anisotropic etching is performed as indicated by an arrow r in a direction substantially perpendicular to the surface 1a of the transparent substrate 1 from the hard mask layer 4 side.
First, the exposed portion 50 of the patterned resist layer 3 is etched away by the first anisotropic etching. Further, in the next anisotropic etching, the processing target layer 2 exposed by removing the exposed portion 50 is etched and removed, and as shown in FIG. The surface 1a is exposed.
At this time, using the hard mask layer 4 left in the concave portion 53 as a mask, the patterned resist layer 3 on the bottom surface 53a of the concave portion 53 is not etched and becomes a residual portion 50c. Further, the processing target layer 2 is not etched using the remaining portion 50c as a mask, and the fine pattern 19 including the processing target layer 2, the patterned resist layer 3, and the hard mask layer 4 is shown in FIG. Is formed.

  Note that a step of removing the hard mask layer 4 and the patterned resist layer 3 by immersing in a resist removing solution after the etching step may be performed. By performing this process, as shown in FIG. 2D of Embodiment 1, a fine pattern 10 in which the processing target layer 2 is formed on the surface 1a of the transparent substrate 1 can be formed.

  In the fine pattern manufacturing method according to an embodiment of the present invention, after the hard mask material 40 is formed, the ashing method or the polishing method is used until the upper surface 3a of the patterned resist layer 3 is exposed. Since the hard mask material 40 left in the concave portion 53 is made the hard mask layer 4 by removing the surface side 40b, the hard mask layer 4 can be easily formed, and the manufacturing efficiency of the fine patterns 19 and 10 can be improved. It can be improved and the production cost can be reduced.

(Embodiment 5)
Next, an optical element that is an embodiment of the present invention will be described.
6A and 6B are diagrams illustrating an example of an optical element according to an embodiment of the present invention, in which FIG. 6A is a schematic perspective view, and FIG. 6B is an AA view of FIG. It is a cross-sectional schematic diagram in a line.

  As shown in FIG. 6, the optical element 30 is formed by laminating a processing target layer 2 made of a metal layer, a patterned resist layer 3, and a hard mask layer 4 made of another metal layer on the transparent substrate 1, This is an optical element 30 provided with a fine pattern 13 in which the three-layer structure 70 is formed in a grid shape. In addition, the same code | symbol is attached | subjected and shown about the member similar to the member used in Embodiment 1. FIG.

In the optical element 30, the three-layer structure 70 having a substantially rectangular cross-sectional shape is formed on the upper surface 1 a of the transparent substrate 1 as a line having a substantially rectangular cross-section having a width W and a height l. They are formed in parallel by p-W. The three-layer structure 70 is formed such that the width W, the height l, the period p of each line, and the interval p-W are several hundred nm or less.
The three-layer structure 70 is configured by laminating a processing target layer 2 made of a metal layer, a patterned resist layer 3, and a hard mask layer 4 made of a metal layer.

  The transparent substrate 1 is made of a plate-like or film-like transparent material. Therefore, the fine pattern 13 can be stably held and can be used stably as the optical element 30.

The processing target layer 2 made of a metal layer is formed, for example, by containing one or more metals of Al, Au, and Ag. By doing in this way, the characteristic of the optical element 30 can be improved. In particular, when the optical element 30 is used as a grid polarizer, the processing target layer 2 made of a metal layer is preferably made of Al. This is because the extinction ratio can be improved. The processing target layer 2 made of a metal layer may be made of an alloy made of a plurality of types of metals, or may be made of a structure made of a plurality of metal layers.
The height t of the processing target layer 2 made of a metal layer is set in consideration of the width w of the recess. This is because the aspect ratio t / w is related to optical characteristics such as the extinction ratio (contrast) and transmittance of the optical element 30.

  The patterned resist layer 3 made of a transparent dielectric material is not particularly limited as long as it is highly transparent in the visible light region, but higher transmittance can be achieved by increasing the acrylic material content. As such a resist, for example, PAK-01 manufactured by Toyo Gosei Co., Ltd. can be used.

  The height v of the patterned resist layer 3 of the optical element 30 is preferably 200 nm or more, and more preferably 200 nm to 400 nm. In the three-layer structure 70, when the height v of the patterned resist layer 3 is 200 nm or more, thin film interference hardly occurs in the visible light region, and the extinction ratio (contrast) can be improved.

The hard mask layer 4 made of a metal layer is formed, for example, by containing one or more metals of Ni and Cr. The material of the hard mask layer 4 is preferably a material having high etching resistance. For example, a metal material such as Ni or Cr is a material having high etching resistance. In particular, Ni is a material having high etching resistance. It can be effectively used as a mask in all etching processes.
Further, the height x of the hard mask layer 4 is desirably as high as possible from the viewpoint of optical characteristics. This is because as the aspect ratio x / w of the hard mask layer 4 is larger, it contributes to improvement of the extinction ratio (contrast) and transmittance of the optical element 30.

  The fine pattern 13 includes a three-layer structure 70 formed in a grid shape. Therefore, it can be used as an optical element such as a grid polarizer. In that case, it is preferable that the fine pattern 13 has a width W and a height l within a certain error range as much as possible.

Such a fine pattern 13 is an example, and fine patterns 15, 17 and 19 can be used as described in the previous embodiment.
In addition, as long as a plurality of lines are arranged in parallel with fine gaps, various patterns in which the arrangement position of each line, connection relationship, line width, and the like are changed can be adopted. Further, it may have a fine shape change in an allowable range due to a processing error or the like.
Hereinafter, the present invention will be specifically described based on examples. However, the present invention is not limited only to these examples.

(Example 1)
(Pattern resist layer formation process)
A glass substrate was used as the transparent substrate, and the surface was cleaned by a known cleaning method, and then a metal layer made of Al was formed to a thickness of 175 nm by vapor deposition.

  Next, PAK-01 manufactured by Toyo Gosei Co., Ltd. was applied as a resist on the metal layer, and the mold shape was transferred (patterned) using the nanoimprint method. As a result, a patterned resist layer having recesses with a period of 140 nm, a width of 70 nm, and a height of 275 nm was formed.

(Etching process)
Next, a hard mask layer made of Cr was formed with a film thickness of 25 nm on the upper surface of the patterned resist layer at an evaporation angle θ = 45 ° using an oblique evaporation method.

Next, anisotropic etching was performed in a direction substantially perpendicular to the surface of the transparent substrate from the hard mask layer side, and was left in the concave portion of the fine pattern. The resist residue was removed by etching. In this etching, O ₂ was used as the gas species, the gas pressure of the gas was 1 Pa, and the bias power was 500 W.

Furthermore, the metal layer was etched. This etching is divided into two stages, in which the natural oxide film on the surface of the metal layer is removed in the first half step and the metal layer body is etched in the second half step. As the gas type, BCl ₃ was used in the first half step, and Cl ₂ was used in the _second half step. The gas pressure of the gas was 1 Pa and the bias power was 500 W, respectively.

In this way, a glass substrate was used as the transparent substrate, Al (height 175 nm, width 70 nm) was used as the metal layer, and PAK-01 (height 275 nm, width 70 nm) manufactured by Toyo Gosei Kogyo was used as the patterned resist layer. A fine pattern (period 140 nm) composed of a three-layer structure using Cr (height 25 nm, width 70 nm) as a mask layer was formed on the glass substrate.
The optical characteristics of this optical element were a transmittance of 34.2% and an extinction ratio (contrast) of 99500.

(Comparative Example 1)
In Example 1, except that the thickness of the metal layer was set to 200 nm, Al (height 200 nm, width 70 nm) was used as the metal layer, and PAK-01 (height 275 nm, manufactured by Toyo Gosei Kogyo Co., Ltd.) was used as the patterned resist layer. A fine pattern (period 140 nm) composed of a three-layer structure using Cr (height 25 nm, width 70 nm) as a hard mask layer was formed on the glass substrate.
This was immersed in a resist removing solution, the patterned resist layer and the hard mask layer were removed, and a fine pattern (period 140 nm) made of Al (height 200 nm, width 70 nm) was formed on the glass substrate as a metal layer. An optical element was formed.
The optical characteristics of this optical element were a transmittance of 39.7% and an extinction ratio (contrast) of 48600.

(Comparative Example 2)
In Example 1, Al (height 175 nm, width 70 nm) and Cr (high) were formed in the same manner except that after forming Al of 175 nm thickness, Cr was formed thereon to form a metal layer. A metal layer having a two-layer structure composed of 25 nm in thickness and 70 nm in width), PAK-01 (height 275 nm, width 70 nm) manufactured by Toyo Gosei Co., Ltd. as a patterned resist layer, and Cr (height 25 nm in height) , Width 70 nm) was used to form a fine pattern (period 140 nm) on the glass substrate.
This is immersed in a resist removing solution to remove the patterned resist layer and the hard mask layer, and a metal having a two-layer structure composed of Al (height 175 nm, width 70 nm) and Cr (height 25 nm, width 70 nm). An optical element having a fine layer pattern (period 140 nm) formed on a glass substrate was formed.
The optical characteristics of this optical element were a transmittance of 36.7% and an extinction ratio (contrast) of 39300.

  The present invention relates to a method for producing a fine pattern, and is particularly used for a semiconductor element or an optical element, and can be used in the optical member industry or the semiconductor industry.

It is process sectional drawing which shows an example of the fine pattern which is embodiment of this invention. It is process sectional drawing which shows an example of the fine pattern which is embodiment of this invention. It is process sectional drawing which shows an example of the fine pattern which is embodiment of this invention. It is process sectional drawing which shows an example of the fine pattern which is embodiment of this invention. It is process sectional drawing which shows an example of the fine pattern which is embodiment of this invention. It is a cross-sectional schematic diagram which shows an example of the optical element which is embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate, 1a ... Upper surface, 2 ... Processing target layer, 3 ... Patterned resist layer, 3a ... Upper surface, 4 ... Hard mask layer, 10, 13, 15, 17, 19 ... Fine pattern, 30 ... Optical element, 40 ... hard mask material, 40b ... surface side, 42, 42a, 42b ... hard mask layer, 44 ... concave, 45 ... convex, 46 ... mold, 48 ... resist, 50 ... exposed part, 50c ... residual part, 53 ... Recessed portion, 53a ... bottom surface, 53b, 53c ... inner wall surface, 55 ... resist residue, 70 ... structure.

Claims (11)

A processing target layer is formed on a transparent substrate, a resist layer made of a transparent dielectric is formed on the processing target layer, and the resist layer is patterned by a nanoimprint method, thereby having a recess on the upper surface of the resist layer. A patterned resist layer forming step of creating a patterned resist layer;
After forming a hard mask layer made of a metal layer on at least the upper surface of the patterned resist layer, the resist residue left at the bottom of the recess is removed by etching, and then the patterned resist layer is used as a mask. And an etching process for etching the processing target layer.   The method of manufacturing a fine pattern according to claim 1, further comprising a step of removing the hard mask layer and the patterned resist layer after the etching step.   The method for producing a fine pattern according to claim 1, wherein the processing target layer is made of a metal layer.   The said etching process is a process of etching the said resist residue, the natural oxide film formed in the said process target layer which consists of a metal layer, and the said process target layer one by one. The manufacturing method of the fine pattern of any one of these. In the etching step, a gas containing any one of O ₂ , CF ₄ , CHF ₃ , Ar, HCl, Cl ₂ , BCl ₃ , H ₂ , and N ₂ is used as an etching gas for the resist residue.
As an etching gas for the natural oxide film, a gas containing any of CF ₄ , CHF ₃ , Ar, HCl, Cl ₂ , BCl ₃ , H ₂ , and N ₂ is used.
As an etching gas for the metal layer, a gas containing any of CF ₄ , CHF ₃ , Ar, Cl ₂ , and N ₂ is used.
The gas pressure is 0.1 to 10 Pa,
5. The method for producing a fine pattern according to claim 1, wherein dry etching is performed under a condition that the bias power is 10 to 2000 W.   The said etching process WHEREIN: After forming the said hard mask layer on the upper surface of the said patterned resist layer with a vapor deposition method, the said process target layer is etched, The any one of Claims 1-5 characterized by the above-mentioned. A method for producing a fine pattern.   The said etching process WHEREIN: After forming the said hard mask layer on the upper surface of the said patterned resist layer by diagonal vapor deposition, the said process target layer is etched, The any one of Claims 1-5 characterized by the above-mentioned. Method for producing a fine pattern.   In the etching step, the hard mask layer is formed by a sputtering method so that the thickness of the upper surface of the patterned resist layer is thicker than the thickness of the bottom of the recess, and then wet etching is performed to perform the process in the recess. 6. The method according to claim 1, wherein only the hard mask layer is removed, the hard mask layer is formed on an upper surface of the patterned resist layer, and then the processing target layer is etched. Method for producing a fine pattern.   In the etching step, a hard mask material is applied by a wet coating method so as to cover the surface of the patterned resist layer having the recesses, and then the upper surface of the patterned resist layer is exposed using an ashing method or a polishing method. Using the hard mask material left in the recess as the hard mask layer, the exposed portion of the patterned resist layer is removed by etching, and then the layer to be processed is etched using the remaining portion of the patterned resist layer as a mask. The method for producing a fine pattern according to any one of claims 1 to 5, wherein: A fine pattern formed in a grid shape is formed on the transparent substrate,
The optical element, wherein the fine pattern includes a metal layer, a transparent dielectric layer laminated on the metal layer, and another metal layer formed on the transparent dielectric layer.   The optical element according to claim 9, wherein a height of the transparent dielectric layer is 200 nm or more.

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