JPS63113457A - Pattern inverting method - Google Patents

Abstract

PURPOSE:To improve manufacture efficiency and to easily invert a pattern by leaving the reverse part of a surface-treated light shield film as a light shield film pattern on one main surface of a light-transmissive substrate. CONSTITUTION:A thin film 8 is adhered on a substrate 7 and a resist 9 is applied on the thin film 8 and exposed and developed to form a resist pattern 9a on the thin film 8; and the surface of the part 8a of the thin film which is exposed is treated by a dry etching method which uses a reactive gas. Then the resist pattern 9a is removed and the part 8b of the surface-treated thin film is used as a mask to etch the thin film selectively, thereby forming a thin film pattern 8c on the substrate 7. Consequently, the pattern is inverted by using positive type and negative type photoresist and positive type and negative type electron beam resist, the manufacture efficiency is improved, and the pattern is easily inverted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for inverting a pattern formed on a photomask, for example, when manufacturing the photomask.

[Conventional technology]

A conventional method for reversing a pattern will be described with reference to FIG. 3, taking as an example the case of manufacturing a photomask.

First, a light-shielding film 2 made of chromium is deposited by sputtering on the surface of a transparent substrate 1 such as a quartz glass plate that has been polished with high precision. A positive type photoresist 3 (eg, AZ-1350 manufactured by Heast Co., Ltd.) is applied. Next, in order to form a latent image of a predetermined resist pattern, a predetermined area of the positive photoresist 3 is irradiated with a large amount of ultraviolet light 4 to expose the predetermined area of the positive photoresist 3 (see IT3 diagram (a)). . Note that the amount of UV light 4 irradiated multiple times is required to be approximately twice the amount of irradiation during normal positive photoresist exposure.

Next, the amine compound catalyst 5 is positively diffused into the photoresist 3 by a diffusion method in the atmosphere of the amine compound catalyst 5 (see FIG. 3 (1)). The entire surface of the resist 3 is irradiated with ultraviolet light 6 (so-called flood exposure) (see FIG. 3(C)), and the unexposed portions of the positive photoresist 3 when irradiated with ultraviolet light 4 are exposed to the current Bi solution. Increases dissolution rate. next,
The unexposed portions of the positive photoresist 3 when irradiated with the ultraviolet light 4 are removed using a developer to form a resist pattern 3a on the light-shielding film 2 (see FIG. 3(d)).

Next, using an etching solution, the exposed light-shielding film 2 is etched using the resist pattern 3a as a mask to form a light-shielding film pattern 2a on the −1 surface of the light-transmitting substrate 1 (see FIG. 3(e). )reference). Next, the resist pattern 3a is removed using a resist removal solution to form a light-shielding film pattern 2a on the -1 surface of the light-transmitting substrate 1, and a photomask is mounted (see Fig. 3). reference).

By the way, normal exposure, development, etching and etching can be carried out without irradiating the positive photoresist 3 with a large amount of ultraviolet light 4, diffusing the amine compound catalyst 5, and flood exposure with ultraviolet light 6 as described above. When a light-shielding film pattern is formed through a photolithography process called resist pattern peeling, the light-shielding film 2 remains under the unexposed portion of the positive photoresist 3, as shown in FIG. 2b is formed on the -1 surface of the transparent substrate 1. That is, the light-shielding film pattern 2a (see FIG. 3m) is an inverted light-shielding film pattern with respect to the light-shielding film pattern 2b formed corresponding to the unexposed portion of the positive photoresist 3. .

[Problem that the invention seeks to solve]

However, in the conventional pattern reversal method as described above, pattern reversal is possible only when a diazo/novolac type positive photoresist is used as the resist. That is, the resist is a positive type photoresist other than diazo/novolac type, or a negative type photoresist.

When using positive type and negative type electron beam resists, pattern reversal cannot be performed.

Further, in order to expose a predetermined area of the positive photoresist 3 by irradiating the positive photoresist 3 with the ultraviolet light 4 at a high concentration, a large amount of exposure energy is required. Roughly,
It takes about 1 to 2 hours to perform the diffusion treatment of the amine compound catalyst 5 into the positive photoresist 3, resulting in a decrease in the TlA production efficiency of photomasks and the like.

Furthermore, in order to carry out the diffusion treatment of the amine compound catalyst 5 and the flood exposure with ultraviolet light 6, dedicated expensive equipment is required.

The present invention was made in view of the above-mentioned circumstances, and is capable of reversing a pattern using a positive photoresist, a negative photoresist, a positive electron beam resist, and a negative electron beam resist. Furthermore, it is an object of the present invention to provide a method that can improve manufacturing efficiency and easily perform pattern reversal.

Means for Solving Problem C] The present invention has been made in order to achieve the above-mentioned object. 1, apply a resist on the thin film, then expose and develop the resist to form a resist pattern on the double film, and then dry etching using a reactive gas to form a resist pattern on the thin film. A thin film pattern is formed on the substrate by surface-treating a portion of the film and removing the resist pattern, and then selectively etching the thin film using the surface-treated portion of the thin film as a mask. This is a pattern reversal method. Further, a sub-aspect of the present invention is a pattern reversal method characterized in that the thin film contains chromium and the reactive gas contains fluorine.

[Example 1] Hereinafter, a pattern reversal method according to Example 1 of the present invention will be described with reference to FIG. 1, taking the case of manufacturing a photomask as an example.

First, a transparent substrate 7 (dimensions: 5 x 5 x 0.09 inches) made of quartz glass whose amphibious surfaces have been polished with high precision is prepared, and then chromium oxide is deposited on the −1 surface of the transparent substrate 7 by sputtering. A light-shielding film 8 (as a thin film consisting of
Film thickness: 1000 coats). Next, a negative electron beam resist 9 (e.g., Toyo Soda Kogyoku CMS-EX (SS), film thickness: 5000) is coated on the light-shielding film 8 by a spin code method (see Fig. 1(a)). ). Next, an electron beam exposure device (e.g. Perkin-Nilmer Co., Ltd. v!A) 4E
Using BES-I [1], electron l! is generated based on predetermined exposure pattern data. ; 110, a predetermined area of the negative electron beam resist 9 is exposed (see FIG. 1(b)). next,
The negative electron beam resist 9 is developed using a developer (for example, a developer exclusively for 0MS), and the unexposed portions are removed to form a resist pattern 9a on the light-shielding film 81, thereby forming a photomask blank 11 with a resist pattern. (Figure 1 (C)
)reference).

Next, a photomask blank 11 with a resist pattern
is placed in a reaction chamber of a parallel plate type dry etching apparatus, a reactive gas consisting of a mixture of CFa gas and 02 gas is introduced into the reaction chamber, and a gas plasma etching method is used to remove the resist pattern 9a from being covered by the resist pattern 9a. The exposed portion 8a of the light-shielding film (see FIG. 1(C)) is surface-treated for a predetermined time (this example; 5 minutes) to form a surface-treated portion 8b of the light-shielding film. During the surface treatment by this gas plasma etching method, the resist pattern 9a on the light-shielding film 8 is vaporized and disappears (see FIG. 1(d)). The processing conditions for surface treatment using this gas plasma etching method are as follows: 1 CF4 gas stream: 101005c, Q
2 gas flow suspension: 50sec, gas pressure = 30Pa, R
F electric crab 0-3W/c2Turu. Next, using the above-mentioned parallel plate type dry etching apparatus, under the same processing conditions as those during surface processing by the above-mentioned gas plasma etching method, using the surface-treated portion 8b of the light-shielding film as a mask, a gas The light-shielding film 8 is selectively etched for a predetermined period of time (in this example: 20 minutes) using a plasma etching method to form a light-shielding film pattern 8C on the entire surface of the light-transmitting substrate 7 (FIG. 1(e)). reference). Furthermore, at this time,
The part of the light-shielding film 8 covered by the resist pattern 9a (see FIG. 1(C)) is etched, and the part of the light-shielding film 8 below the surface-treated light-shielding film part 8b becomes light-transmitting. The light shielding film pattern 8C remains on one main surface of the transparent substrate 7.

That is, the light-shielding film pattern 8C is inverted with respect to the light-shielding film pattern (not shown) that is supposed to remain and be formed under the resist pattern 9a, which is the exposed portion of the negative electron beam resist 9. ing.

As described above, according to the pattern reversal method according to the present embodiment, using a negative electron beam resist, the light-shielding film pattern that is to be formed remaining under the resist pattern 9a is reversed. A film pattern 8C can be formed. Further, when the surface area of the light-shielding film pattern 8C that remains and is formed on the surface of the light-transmitting substrate 7 during its lifetime is larger than the surface area of the light-shielding film 8 that is removed from the surface of the light-transmitting substrate 7 during its lifetime. By employing the pattern reversal method according to this embodiment, the area to be exposed can be narrowed, so that the desired light-shielding film pattern 8C can be formed in a shorter exposure time.

By the way, in this example, the exposed portion 8 of the light-shielding film
After the surface treatment of a, the light-shielding film 8 was selectively etched by gas plasma etching. However, after the exposed light-shielding film part 8a is surface-treated, it is etched in an etching solution (e.g., a solution made by adding pure water to 165LJ of ceric ammonium nitrate and 42JM of perchloric acid (70%) to make 1000D). The light-shielding film 8 is immersed for a predetermined period of time (60 seconds in example 2), and the light-shielding film pattern 8C is selectively etched using a wet etching method using the surface-treated portion 8b of the light-shielding film as a mask to make the light-shielding film pattern 8C translucent. It may also be formed on the entire surface of the substrate 7.

Further, in this embodiment, a negative type electron beam resist is used as the resist, but the light shielding film pattern can be reversed and formed even if a positive type electron beam resist is used.

[Example 2] Hereinafter, a pattern reversal method according to Example 2 of the present invention will be described with reference to FIG. 2, taking the case of manufacturing a photomask as an example.

First, as in Example 1, a light-transmitting substrate 7 is prepared, and a light-shielding film 8 is deposited on its main surface. Next, a positive photoresist 12 (eg, AZ~1350 manufactured by Hoechst Co., Ltd., film thickness: 5000) is coated on the light-shielding film 8 by a spin code method (see FIG. 2(, 1)). Next, in order to form a latent image of a predetermined resist pattern, a predetermined area of the positive photoresist 12 is irradiated with ultraviolet light 13 to expose a predetermined area of the positive photoresist (see FIG. 2(b)).

Next, the Bo 2 type photoresist 12 is developed using a developer (for example, an AZ exclusive developer), the exposed portion is removed, a resist pattern 12a is formed on the light-shielding film 8, and a resist pattern is formed. Obtain a photomask blank 14 (second
(See figure (C)).

Next, a photomask blank 14 with a resist pattern is
is placed in a reaction chamber of a parallel plate type dry etching apparatus, a reactive gas consisting of a mixture of CF4 gas and 02 gas is introduced into the reaction chamber, and exposed without being covered by the resist pattern 12a by a gas plasma etching method. The surface treated portion 8d of the light-shielding film (see FIG. 2(C)) is subjected to surface treatment for a predetermined time (this example; 5 minutes) to form a surface-treated portion 8e of the light-shielding film. Note that during the surface treatment by this gas plasma etching method, the resist pattern 12a on the light-shielding film 8 is vaporized and disappears (see FIG. 2(d)).

The conditions for surface treatment by this gas plasma etching method are the same as those described in Example 1. Next, in the same manner as in Example 1, using the surface-treated portion 8e of the light-shielding film as a mask, the light-shielding film 8 is selectively etched for a predetermined period of time (in this example: 20 minutes) by gas plasma etching. The light-shielding film pattern 8f is placed on the light-transmitting substrate 7.
1 surface (see FIG. 2(e)). At this time, the resist pattern 12a (see Fig. 2(c))
The part of the light-shielding film 8 that was covered by the etching process is etched, and the part of the light-shielding film 8 below the surface-treated light-shielding film part 8e remains on the entire surface of the light-transmitting substrate 7. This is a light-shielding film pattern 8f. That is, the light-shielding film pattern 8f is inverted with respect to the light-shielding film pattern (not shown) that is supposed to remain and be formed under the resist pattern 12a, which is the unexposed portion of the positive photoresist 12. There is.

As described above, according to the pattern reversal method according to this practical example, using a positive photoresist, it is possible to easily reverse the pattern with respect to the light-shielding film pattern that is supposed to remain and be formed under the resist pattern 12a. A light-shielding film pattern 8f can be formed.

By the way, in this example, the exposed portion 8 of the light-shielding film
After the surface treatment of d, the light-shielding film 8 was selectively etched by gas plasma etching. However, Example 1
Part 8 of the light-shielding film was surface-treated in the same manner as in the case of
The light-shielding film pattern 8f may be formed on the −1 surface of the light-transmitting substrate 7 by selectively etching the light-shielding film 8 using the mask e as a mask by a wet etching method.

Further, in this embodiment, a positive photoresist is used as the resist, but the light-shielding film pattern can be reversed and formed even if a negative photoresist is used.

As described above, according to the pattern reversal methods according to Examples 1 and 2 of the present invention, positive-type and negative-type photoresists,
In addition, pattern reversal can be performed using positive and negative electron beam resists. In addition, there is no need to diffuse an amine compound catalyst into the positive photoresist as in the conventional pattern reversal method, which improves manufacturing efficiency when manufacturing photomasks by reversing patterns. can. Further, since it is not necessary to carry out the diffusion treatment of the amine compound catalyst and the devices for performing the above-mentioned flood exposure, the pattern can be easily reversed.

The present invention is not limited to Examples 1 and 2 described above.

The light-shielding film 8 is made of chromium oxide, and is made of chromium, chromium oxide, chromium carbide, or chromium nitride.

It may contain at least one of chromium boride and chromium sulfide, or it may be formed by laminating thin films containing at least one of these. Also,
The method of forming the light shielding film 8 is not limited to the sputtering method,
Vacuum deposition method, CVD method.

A film forming method such as an ion blating method may be used,
The film thickness can also be appropriately determined depending on conditions such as desired optical density. Moreover, between the light-shielding film 8 and the light-transmitting substrate 7,
A thin film made of a metal silicide such as molybdenum silicide or tungsten silicide, or an aluminum cap may be interposed.

The reactive gas used in the surface treatment of the exposed light-shielding film portions 8a and 8d by gas plasma etching is C.
Although it contains F4 gas, it contains N instead of CF4 gas.
F3, C2F6.

A gas containing fluorine such as CBrF3 gas may be used.

Further, the treatment conditions during the surface treatment are not limited to those described in Example 1, and may be appropriately selected.

Further, the surface treatment may be performed by a dry etching method such as a reactive ion etching method other than the gas plasma etching method.

In Examples 1 and 2, the light-shielding film patterns 8b and 8e formed on the surface 98 are used as masks to prevent the light-shielding film 8 from being exposed.
When selectively etching, gas plasma etching was used, but the etching conditions were selected with appropriate RF, and dry etching methods such as reactive ion etching, sputter etching, etc. Wet etching methods other than the dipping method described in Examples 1 and 2 above may be employed.

It goes without saying that the etching solution is not limited to that described in Example 1.

Furthermore, the light-shielding film 8 is etched using a gas plasma etching method.
The reactive gas used for selectively etching is C
It may contain a gas containing fluorine as described above other than F4 gas.

The transparent substrate 7 may be made of materials other than quartz glass, such as soda lime glass, aluminosilicate glass, aluminoborosilicate glass, and sapphire. Also,
In Examples 1 and 2 above, the light-transmitting substrate 7 was used as the substrate, but the substrate is not necessarily limited to having light-transmitting properties. For example, a substrate made of Si tGaAs or a silicon oxide film It may also be a 3i75 board or the like coated with.

The resists 9 and 12 may be applied by a coating method such as a spray coating method or a roll coating method other than the spin code method.

〔Effect of the invention〕

According to the pattern reversal method of the present invention, patterns can be reversed using positive-type and negative-type photoresists and positive-type and negative-type electron beam resists, and manufacturing efficiency is further improved. Inversion can be performed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the steps of a pattern reversal method according to the first embodiment of the present invention, FIG. 2 is a cross-sectional view showing the steps of the pattern reversal method according to the second embodiment of the present invention, and FIG. 4 is a sectional view showing the steps of the method, and FIG. 4 is a sectional view showing a photomask covering a light-shielding film pattern formed without pattern reversal. 7... Transparent substrate, 8... Light blocking film, Ba. 8d...Exposed light-shielding film portion, 8b, 8e...
Portion of surface-treated light-shielding film, 8c. 8f...Light-shielding film pattern, 9...Negative electron beam resist, 9a, 12a...Resist pattern, 10.
...Electron beam, 12...Positive photo]-resist, 13
...ultraviolet light

Claims (2)

[Claims] (1) Deposit a thin film on a substrate, apply a resist on the thin film, then expose and develop the resist to form a resist pattern on the thin film, and then dry etching using a reactive gas. The exposed portion of the thin film by the method is surface-treated and the resist pattern is removed, and then the thin film is selectively etched using the surface-treated portion of the thin film as a mask to transfer the thin film pattern to the substrate. A pattern reversal method characterized by forming a pattern on the top. (2) Claims characterized in that the thin film contains chromium and the reactive gas contains fluorine (
1) Pattern reversal method described in section 1).