JPH08110630A - Production of grating mask - Google Patents

Abstract

PURPOSE: To provide a process for producing a grating mask by which the grating mask is easily obtd. CONSTITUTION: A quartz substrate 10 is spin coated with an MIBK soln. contg. a poly(di-t-butoxysiloxane) as a radiation sensitive resin compsn. and 10wt.% triphenyl sulfonium triferate as an acid generating agent and is then subjected to heating, by which an SOG film 12 is formed at a thickness of 400nm. Next, this SOG film 12 is subjected to exposing, then to baking and developing, by which SOG film patterns 14 having periodic patterns are formed. The SOG film 12 is plotted with line and spaces of a depth of 250nm by using electron beams in this embodiment. Next, the SOG film 12 subjected to plotting is heated and developed, by which the patterned films 14 of the SOG are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a grating mask used for manufacturing a grating of an element such as an optical filter, a DFB laser or a DRB laser used in optical communication technology by an interference exposure method.

[0002]

2. Description of the Related Art Conventionally, in order to obtain a grating having good wavelength conversion efficiency, processing with high dimensional accuracy (for example, about 200 nm) is required. Achieving this dimensional accuracy is usually extremely difficult with photolithographic techniques.

Therefore, a method of manufacturing a grating by an interference exposure method using a grating mask is disclosed in a literature:
"Journal of Vaccum Science
end Technology B10 (6), 19
92, pp. 2530-2535 ".
According to the technique disclosed in this document, a three-layer resist pattern is formed by using electron beam direct writing and dry etching methods, and this is used as an etching mask to engrave a substrate to a certain depth by dry etching. Then, the grating mask is formed.

[0004]

However, in the conventional method disclosed in the above document, it is necessary to form a three-layer resist pattern, so that the process is complicated. Specifically, three steps are required to form a three-layer resist layer on a mask blank with chrome, and the three resist layers are etched to form a three-layer resist pattern. Three steps are required, and two steps are required for processing the mask substrate.

As described above, as a result of complicated processes, factors that deteriorate the mask performance such as dimensional conversion error and non-uniformity of pattern depth within the mask surface are increased. further,
Since the equipment used in each step is also required, the manufacturing cost increases.

Therefore, it has been desired to realize a method for manufacturing a grating mask which can easily obtain the grating mask.

[0007]

According to the method of manufacturing a grating mask of the present invention, a radiation containing a resin which is decomposed by the action of an acid and an acid generator which is decomposed by the radiation to generate an acid on a transparent substrate. A step of applying a sensitive resin composition to form an SOG (spin-on-glass) film, and a step of exposing the SOG film, followed by baking and development to form an SOG film pattern having a periodic pattern. It is characterized by including and.

Preferably, the transparent substrate is dry-etched by using the SOG film pattern as an etching mask, and
It is preferable to transfer the G film pattern.

However, the radiation includes ultraviolet rays, visible rays, X-rays and electron rays.

[0010]

According to the method of manufacturing a grating mask of the present invention, an SOG film pattern is formed using a radiation sensitive resin composition. This radiation-sensitive resin composition can be obtained, for example, by adding an acid generator that generates an acid in response to radiation to a commercially available SOG material.

When this radiation-sensitive resin composition is used as an SOG film, it is more sensitive than ordinary resists, and if a resin which is substantially vitreous, such as poly (di-t-butoxysiloxane), is used. , Substantially glassy S
An OG film pattern can be easily obtained. Further, in the present invention, since this SOG film pattern can be used as it is as the grating mask, the grating mask can be easily obtained. Further, when the SOG film pattern is used as it is as a grating mask, the dimensional accuracy of the pattern is determined only by the accuracy at the time of forming the SOG film pattern, for example, the drawing accuracy at the time of electron beam drawing. Therefore, the factors that deteriorate the mask performance, such as the dimension conversion error and the non-uniformity of the pattern depth within the mask surface, are far fewer than those in the conventional example. Therefore, a grating mask with good dimensional accuracy can be easily obtained.

Further, by transferring the SOG film pattern to the transparent substrate, a grating mask having excellent durability and light resistance can be easily obtained even when a non-glass material such as organic SOG is used.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a method for manufacturing a grating mask of the present invention will be described below with reference to the drawings. Numerical conditions such as materials used, materials usage fee, processing time, temperature, and film thickness described in the following description are only suitable examples within the scope of the present invention. Therefore, the present invention is not limited to these conditions. In the following drawings,
The hatching showing the cross section is partially omitted.

<First Embodiment> (A) and (B) of FIG.
FIG. 4 is a cross-sectional process diagram for explaining the first embodiment of the method for manufacturing a grating of the present invention.

First, a transparent substrate 10 is coated with a radiation-sensitive resin composition containing a resin that decomposes by the action of an acid and an acid generator that decomposes by radiation to generate an acid.
The film 12 is formed. In this embodiment, as the transparent substrate 10, a 4-inch square quartz substrate 10 with a chrome frame pattern 22 is used. In addition, as a radiation-sensitive resin composition,
A MIBK solution containing a resin of poly (di-t-butoxysiloxane) and 10 wt% of triphenylsulfonium triflate as an acid generator is used.
Then, this MIBK solution is spin-coated on a quartz substrate and then baked on a hot plate at a temperature of 80 ° C. for 1 minute to form an SOG film 12 having a thickness of 400 nm ((A) of FIG. 1).

Next, after exposing this SOG film 12, baking and development are performed to form an SOG film pattern 14 having a periodic pattern. In this embodiment, the SOG film 1
2, the electron beam having an accelerating voltage of 20 kV is used, and 100 nm wide lines are arranged at a pitch of 25 n as a periodic pattern.
Depth 250 increased by 1 nm from m to 240 nm
Exposure is performed by drawing line and space (hereinafter, also referred to as L / S) of nm as a periodic pattern. Painted SOG film on a hot plate at 100 ℃
Bake at the temperature, develop with anisole for 30 seconds and rinse with xylene for 30 seconds. 20 more
The SOG film pattern film 14 is formed by baking at a temperature of 0 ° C. for 10 minutes. The obtained SOG film pattern is SEM
As a result, it was confirmed that an L / S pattern having a thickness of 250 nm was formed (FIG. 1 (B)).

The SOG film pattern obtained from the radiation-sensitive resin composition used in this example is substantially vitreous. Therefore, this SOG film pattern has excellent durability and light resistance and is suitable for use as it is as a grating mask.

The measurement results of the performance when the SOG film pattern is used as it is as a grating mask will be described below.

In the measurement, this SOG film pattern grating mask was mounted on a rotary stage, and the diffraction efficiency of the first-order diffracted light with respect to the transmitted light of an argon ion laser (wavelength 363.8 nm) was measured by changing the pitch of the grating. The measurement result shows that the diffraction efficiency is 0. 0 when the ratio of the line width to the grating pitch is 30%.
It was 45, and the diffraction efficiency near this ratio was the maximum.
The diffraction efficiencies at the ratios of 40% and 60% were 0.25% and 0.08%, respectively. From these diffraction efficiency values, it was found that in this example, the same tendency and performance as the diffraction efficiency values of the conventional grating mask described in the above-mentioned literature were obtained.

<Second Embodiment> First, a radiation-sensitive resin composition containing a resin that decomposes by the action of an acid and an acid generator that decomposes by radiation to generate an acid is coated on a transparent substrate. An SOG film is formed. In this embodiment, a 4-inch square quartz substrate with a chrome frame pattern 22 is used as the transparent substrate. In addition, as a radiation-sensitive resin composition,
A solution obtained by dissolving 1 wt% of triphenylsulfonium triflate as an acid generator in a solution of a resin of OCD-Type 7 (trade name) manufactured by Tokyo Ohka is used. Then, after spin coating this solution on a quartz substrate,
A 250-nm-thick SOG film is formed by baking at a temperature of 80 ° C. on a hot plate.

Next, after exposing this SOG film, baking and development are performed to form an SOG film pattern having a periodic pattern. In this embodiment, for the SOG film,
An electron beam with an accelerating voltage of 20 kV was used, and 100 nm wide lines were formed as a periodic pattern at a pitch of 25 nm to 240 n.
Exposure is performed by drawing a line and space (hereinafter, also referred to as L / S) having a depth of 250 nm increased by 1 nm in increments of m as a periodic pattern. The drawn SOG film is baked on a hot plate at a temperature of 100 ° C., developed with anisole for 30 seconds, and then developed with xylene.
Rinse for 0 seconds. This is further heated at a temperature of 200 ° C for 10
The SOG film pattern film is formed by baking for a minute. When the obtained SOG film pattern was observed by SEM, it was confirmed that an L / S pattern having a thickness of 230 nm was formed.

The measurement results of the performance when the SOG film pattern is used as it is as a grating mask will be described below.

For the measurement, this SOG film pattern grating mask was mounted on a rotary stage and Ar was used.
The diffraction efficiency of the first-order diffracted light with respect to the transmitted light of the ion laser (wavelength 363.8 nm) was measured by changing the pitch of the grating. The measurement result shows that the diffraction efficiency is 0.42 when the ratio of the line width to the grating pitch is 30%.
The diffraction efficiency near this ratio was maximum. Further, the diffraction efficiencies when the ratio was 40% and 60% were 0.21% and 0.05%, respectively. From these diffraction efficiency values, it was found that in this example, the same tendency and performance as the diffraction efficiency values of the conventional grating mask described in the above-mentioned literature were obtained.

<Third Embodiment> FIGS. 2A to 2C show
FIG. 6 is a cross-sectional process diagram that is used for describing a third embodiment of the method for manufacturing a grating of the present invention.

First, using the same materials and conditions as in the second embodiment, the radiation sensitivity of the quartz substrate 10 including a resin decomposed by the action of an acid and an acid generator decomposed by radiation to generate an acid. The resin composition is applied to form the SOG film 16 ((A) of FIG. 2).

Next, under the same method and conditions as those of the second embodiment, the SOG film 16 is exposed and then baked and developed to form an SOG film pattern 18 having a periodic pattern ((B) of FIG. 2). .

By the way, the SOG film pattern formed from OCD-Type 7 used as the radiation-sensitive resin composition in the second and third embodiments becomes an organic SOG film pattern. Therefore, durability and light resistance are inferior to those of the obtained inorganic SOG film pattern of the first embodiment. Therefore,
In the third embodiment, the SOG film pattern is used as an etching mask, and the transparent substrate is dry-etched to transfer the pattern of the SOG film pattern to the transparent substrate.

In performing dry etching for transferring a pattern onto a quartz substrate, a parallel plate type dry etcher is used, and CHF ₃ and O are used as etchants.
A mixed gas obtained by mixing 20 sccm and ₂ sccm with each other is used. This mixed gas has a selectivity of about 1 with respect to the quartz substrate and the SOG film pattern. Then, using a quartz substrate with an rf power density of 0.12 W / cm ² ,
Etching is performed to a depth of about 30 nm. When the dry-etched quartz substrate was observed using an SEM, it was confirmed that the SOG film pattern pattern was transferred to the quartz substrate and a mask pattern 20 was obtained (FIG. 2C).

The measurement results of the performance when this mask pattern is used as a grating mask will be described below.

In the measurement, this grating mask was mounted on a rotary stage, and the diffraction efficiency of the first-order diffracted light with respect to the transmitted light of an Ar ion laser (wavelength 363.8 nm) was measured by changing the pitch of the grating. As a result of the measurement, the diffraction efficiency was 0.47 when the ratio of the line width to the grating pitch was 30%, and the diffraction efficiency in the vicinity of this ratio was the maximum. The diffraction efficiencies at the ratios of 40% and 60% were 0.28% and 0.12%, respectively. From these diffraction efficiency values, it was found that in this example, the same tendency and performance as the diffraction efficiency values of the conventional grating mask described in the above-mentioned literature were obtained.

In each of the above-described embodiments, the present invention has been described as an example in which a specific material is used and formed under specific conditions, but the present invention can be modified and modified in many ways. For example, the exposure of the SOG film described above was performed by drawing with an electron beam, but in the present invention, for example, light or X
The SOG film may be exposed by transferring a pattern with lines.

[0032]

According to the method for manufacturing a grating mask of the present invention, the SOG using the radiation-sensitive resin composition is used.
Form a film pattern. This radiation-sensitive resin composition can be obtained, for example, by adding an acid generator that generates an acid in response to radiation to a commercially available SOG material.

When this radiation-sensitive resin composition is used as an SOG film, it is more sensitive than ordinary resists, and if a resin which becomes substantially vitreous such as poly (di-t-butoxysiloxane) is used. , Substantially glassy S
An OG film pattern can be easily obtained.

Further, in the present invention, since this SOG film pattern can be used as it is as a grating mask, a grating mask can be easily obtained. When the SOG film pattern is used as it is, the dimensional accuracy of the pattern is determined only by the drawing accuracy at the time of forming the SOG film pattern, for example, at the time of electron beam drawing. Therefore, the factors that deteriorate the mask performance, such as the dimension conversion error and the non-uniformity of the pattern depth within the mask surface, are far fewer than those in the conventional example. Therefore, a grating mask with good dimensional accuracy can be easily obtained. Further, by transferring the SOG film pattern to the transparent substrate, a grating mask having excellent durability and light resistance can be easily obtained even when a non-glass material such as organic SOG is used.

[Brief description of drawings]

FIG. 1A and FIG. 1B are cross-sectional process charts for explaining the first embodiment.

FIG. 2A to FIG. 2C are sectional process drawings for explaining the third embodiment.

[Explanation of symbols]

 10: Quartz substrate 12: SOG film 14: SOG film pattern 16: SOG film 18: SOG film pattern 20: Mask pattern 22: Chrome frame pattern

Claims (2)

[Claims] 1. A transparent substrate is coated with a radiation-sensitive resin composition containing a resin that decomposes by the action of an acid and an acid generator that decomposes by radiation to generate an acid.
n-on-glass) film forming step, and a step of forming an SOG film pattern having a periodic pattern by performing baking and development after exposing the SOG film, Production method. 2. The method of manufacturing a grating mask according to claim 1, wherein the transparent substrate is dry-etched by using the SOG film pattern as an etching mask to thereby form the SOG film pattern on the transparent substrate. A method for manufacturing a grating mask, which comprises transferring the pattern of 1.