JPS6332935A - Method for reversing pattern - Google Patents

Abstract

PURPOSE:To enhance the efficiency of an inverting method for a pattern by coating a negative type electron resist pattern formed on a first thin film of a substrate and the exposed first film with a second thin film having an etching resistance of the first film on the first film, separating it together with the pattern and then etching the first film. CONSTITUTION:One main surface of a light transmission substrate 1 is covered with a light shielding film 2 made of molybdenum silicide, and coated with a negative type electron beam resist 3. Then, the predetermined region of the resist 3 is exposed with an electron beam 4, developed to form a pattern 3, and then postbaked. Thereafter, the pattern 3a and the exposed film 2 are covered with a chromium thin film 5, the pattern 3 and the film 5 on the pattern 3a are separated with a separating solution to form a pattern 5a. Subsequently, with the pattern 5a as a mask the film 2 is dry etched to form the pattern 2a, and the substrate 1 is cleaned with thermal conc. sulfuric acid. Then, the pattern 5a is removed with a corresponding etchant, and a photomask of the pattern 2a is manufactured. Thus, a desired pattern can be formed in a short exposing time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for reversing a pattern formed on a semiconductor integrated circuit or a photomask, for example, when manufacturing a semiconductor integrated circuit or a photomask. The present invention relates to a pattern inversion method suitable for use when a dry etching process is included in the manufacturing process of semiconductor integrated circuits or photomasks.

[Conventional technology]

In recent years, as semiconductor integrated circuits such as ICs and LSIs have become more highly integrated, there has been a demand for finer line widths of patterns formed on photomasks used in the manufacturing process, for example. Therefore, in order to form a pattern with a fine line width, a photomask is manufactured by employing an electron beam exposure method using an electron beam and a dry etching method.

A method for manufacturing a photomask using an electron beam exposure method and a dry etching method will be described below.

First, a light-shielding film made of molybdenum silicide (MoSi) W is deposited on the surface of a precision-polished translucent substrate such as quartz glass using a film-forming method such as sputtering.
On this light-shielding film, there is a positive or negative muntin wire resist i.
・Apply. Next, the above-mentioned electron beam resist l- is exposed to an electron beam using an electron beam exposure apparatus based on predetermined electron beam exposure pattern data. Next, the above-mentioned electron beam resist is developed, and the exposed portion in the case of a positive electron beam resist is removed, and the unexposed portion in the case of a negative electron beam resist is removed to form a resist pattern into a light-shielding crotch. Then, the light-shielding film is selectively etched and the resist pattern is peeled off by dry etching to form a predetermined light-shielding film pattern on the surface of the light-transmitting substrate. Making masks.

[Problem that the invention seeks to solve]

However, when using a positive type electron beam resist as an electron beam resist, a positive type electron beam resist with sufficient dry etching resistance has not yet been obtained, so dry etching is performed to form a light-shielding film. Before the selective etching is completed, the resist pattern made of positive electron beam resist evaporates and disappears from the light-shielding film.

Then, it is impossible to manufacture a photomask in which a predetermined light-shielding film pattern to be formed corresponding to a resist pattern is formed on the entire surface of a light-transmitting substrate.

As mentioned above, a positive electron beam resist with sufficient dry etching resistance has not yet been obtained, but currently many negative electron beam resists with sufficient dry etching resistance have been obtained. ing.

By the way, if the surface area of the light-shielding pattern formed on the surface of the light-transmitting substrate during its lifetime is larger than the surface area of the light-shielding film that is removed from the surface of the light-transmitting substrate during its lifetime, positive electron beam It is better to use resist. This is because in this case, only a small amount of the exposed area is removed in the development process after exposure of the positive electron beam resist, which means that the exposure time for the positive electron beam resist is reduced, that is, the exposure time of the exposed area is reduced. Time) is also less than C. When electron beam exposure is used, it is possible to form patterns with fine line widths, but it has been pointed out that it takes a long time for exposure and has poor photomask manufacturing efficiency (so-called throughput). has been done.

However, as mentioned above, since there is no positive type electron beam resist with sufficient dry etching resistance, a negative type electron beam resist is used and the electron beam exposure pattern data is reversed.
A method has been adopted in which a negative type electron beam resist is exposed. In this case, it becomes necessary to invert the electron beam exposure pattern data, and furthermore, the surface area of the light-shielding film pattern formed on the surface of the light-transmitting substrate is When the surface area of the light-shielding film is larger than that of the light-shielding film that is removed from above, the resist pattern that remains and is formed in the development process after exposure of the negative muntin beam resist 1- (i.e., the surface area of the negative electron beam resist) Since the number of exposed portions increases, the disadvantage is that the exposure time becomes longer.

The present invention has been made in view of the above circumstances, and eliminates the need to invert the electron beam exposure pattern data using a negative electron beam resist, and furthermore, eliminates the need to invert the electron beam exposure pattern data by using a negative electron beam resist. A pattern that can form and cover a desired pattern in a short exposure time when the surface area of the light-shielding film pattern formed on the main surface of the light-transmitting substrate is larger than the surface area of the light-shielding film to be removed. The purpose is to provide an inversion method.

[Means for Solving the Problems] The present invention has been made to achieve the above-mentioned object, and consists of depositing a first thin film on the permanent surface of a substrate, and depositing a negative type film on the first thin film. Apply an electron beam resist, then expose and develop the negative electron beam resist to form a resist pattern on the first thin film, and then apply the second resist on the resist pattern and the exposed first thin film. - Depositing a second thin film that is resistant to etching of the first thin film, and then peeling off the second thin film deposited on the resist pattern together with the resist pattern to form a second thin film pattern on the first thin film. This is a pattern reversal method characterized in that the -Fi9 film is selectively etched using the second thin film pattern as a mask to form a pattern made of the first thin film.

Further, in this embodiment, the substrate is made of a light-transmitting 7.4 plate, the first thin film is made of a light-shielding film, the first thin film is made of molybdenum silicide, and the second thin film is made of molybdenum silicide. is made of chromium or aluminum.

[Effect]

Since the second thin film is resistant to etching of the first thin film,
When selectively etching the first film to form a pattern of the first film, the second film pattern is not etched.

(Example) Hereinafter, a pattern inversion method according to an example of the present invention will be described in detail with reference to FIG. 1, taking the case of manufacturing a photomask as an example.

First, cut the quartz glass to a predetermined size (e.g. 5x5xO, 09
inch), and precision polishing the ambidextrous surface of this quartz glass to obtain a translucent substrate 1 as a substrate. Next, a light-shielding film 2 (as a first thin film made of molybdenum silicide) is formed on the surface of the light-transmitting substrate 1 by sputtering.
Film thickness: 1000 people.

Next, a negative electron beam resist 3 (for example, C manufactured by Toyo Soda Kogyo Co., Ltd.) is deposited on the light-shielding film 2 (optical density: 3.0).
MS-EX, film pq: 6000A) Coating is performed by the wo:i:'nkoto method (see FIG. 1(a)).

Next, a predetermined area of the negative electron beam resist 3 is exposed to an electron beam 4 based on predetermined electron beam exposure pattern data using an electron beam exposure apparatus (e.g., MEBES-Ill manufactured by Perkin-Lumar, USA). Expose (see FIG. 1(b)). Next, development is performed for a predetermined time (e.g., 60 seconds) using a developer (e.g., CMS-iEX exclusive developer) to remove the unexposed portions of the negative electron beam resist 3 and transform the resist pattern 3a into a light-shielding film. 2 (see FIG. 1C)), and then post-baked for 30 minutes in a nitrogen gas atmosphere at a temperature of 130°C.

Next, the light shielding property g! exposed on the resist pattern 3a and not covered by the resist pattern 3a! A second thin film 5 made of chromium is deposited on the portion 2 by sputtering (see FIG. 1(d)), and then hot concentrated sulfuric acid (
The resist pattern 3a and the part of the second thin film 5 on the resist pattern 3a are peeled off using a stripping solution consisting of a liquid temperature of 90° C. to form a second thin film pattern made of chromium that is inverted compared to the resist pattern 3a. 5a is formed on the light-shielding film 2 (so-called lift-off) (see FIG. 1(e)).

Next, a mixed gas atmosphere consisting of carbon tetrafluoride gas 101005e and oxygen gas 403CCII (pressure crab 30
The light-shielding film 2 is selectively dry-etched for a predetermined period of time (in this example; 3 minutes) using the second thin film pattern 5a as a mask, and the light-shielding film pattern 2a made of molybdenum silicide is attached to the light-transmitting substrate 1. Figure 1 (
f)), then fever cJIIi! acid (liquid temperature: 90℃)
The light-transmitting plate 1 on which the second thin film pattern 5F'i and the light-shielding film pattern 2a are formed is cleaned using the following method.

Next, an etching solution (
Example: Etching for a predetermined period of time (in this example: 50 seconds) using 165 relium ammonium nitrate and 42 d of perchloric acid (70%) and 42 d of pure water to make 1000 d of the second thin film pattern 5a. , and remove the light-shielding film pattern 2a.
A photomask was fabricated by forming a photomask on one surface of a light-transmitting substrate 1 (see FIG. 1(0)). Furthermore, at this time,
The light-shielding film pattern 2a formed on the surface of the light-transmitting substrate 1 is inverted with respect to the resist pattern 3a (see FIG. 1(C)) formed on the light-shielding film 2. There is. That is, if the light-shielding PIA 2 is dry-etched using the resist pattern 3a formed on the light-shielding film 2 as a mask, the portion of the light-shielding film 2 located below the resist pattern 3a will be etched as shown in FIG. remains on the surface of the light-transmitting substrate 1 for a lifetime, forming a light-shielding film pattern 2b compatible with a negative tone. However, the light-shielding film pattern 2a formed through the predetermined steps described in this example including the lift-off step is located below the resist pattern 3a, as shown in FIG. 1(Q). The portion of the light-shielding film 2 that is not exposed remains on the surface of the light-transmitting substrate 1 for a lifetime, forming a light-shielding film pattern 2a, and the pattern made of the light-shielding film is in an inverted state.

As described above, according to the pattern reversal method of this embodiment, the light-shielding film formed on the surface of the light-transmitting substrate can be removed without reversing the electron-beam exposure pattern data using a negative electron-beam resist. The pattern can be reversed.

Furthermore, as shown in FIG. 1 ((7)), the surface area of the light-transmitting substrate 1 is larger than the surface area of the light-shielding film 2 (see FIG. 1(C)), which is removed from the surface of the light-transmitting substrate 1 during its lifetime. When the surface area of the light-shielding film pattern 2a formed on the surface is large, the exposed portion of the negative electron beam resist 3 by the electron beam 4 can be reduced as shown in FIG. 1(b). Therefore, the desired light-shielding film pattern 2a can be formed on the entire surface of the light-transmitting substrate 1 in a short exposure time, and the throughput can be greatly improved.

The present invention is not limited to the embodiments described above.

First, the transparent substrate 1 may be made of aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, sapphire, or the like other than quartz glass, and its dimensions can be determined as appropriate.

In addition to molybdenum silicide, the light-shielding film 2 is made of tungsten silicide, tantalum silicide, and vanadium silicide.

Niobium silicide, Kobal 1-9 silicide, Zirconium silicide.

It may be made of a light-shielding film containing at least one of nickel silicide and molybdenum silicide.

Furthermore, the method for forming the light-shielding film 2 may also be a CVD method, a vacuum evaporation method, an ion-blating method, etc. other than the sputtering method, and the film thickness is not limited to 1000 and may be selected as appropriate. .

Further, the negative electron beam resist 3 is not limited to those exemplified in this example, and may be any material as long as it has sufficient dry etching resistance, and its film thickness may be appropriately selected.
The coating method may also be a spray coating method, a roll coating method, or the like other than the spin cord method. Further, the temperature and time of the post-baking performed after the development of the negative electron beam resist 3 may be determined as appropriate; in general, the post-baking may be performed as needed and is not essential.

Furthermore, although the second thin film 5 made of chromium is deposited by sputtering, it may be deposited by a film forming method such as CVD, vacuum evaporation, or ion blasting. Further, the second thin film 5 may be made of a metal film such as aluminum, titanium, tantalum, etc. that can be lifted off. Just use something.

Further, in this embodiment, the light shielding film 2 was selectively dry etched using a parallel plate active ion etching apparatus, but the dry etching conditions may be selected as necessary. Further, as the dry etching method, in addition to the active ion etching method described in the examples, gas plasma etching method, sputter etching method, ion beam etching method, etc. may be employed.

In addition, in this example, as shown in FIG. 1(f),
After forming the light-shielding film pattern 2a and the second thin film pattern 5a on the surface of the light-transmitting substrate 1, the second thin film pattern 5 is formed.
A was removed, and only the light-shielding film pattern 2a was formed on one surface of the light-transmitting substrate 1, as shown in FIG. 1(Q), to produce a photomask. However, the second thin film pattern 5a
After forming the light-shielding film pattern 2a and the second thin film pattern 5a on the surface of the light-transmitting substrate 1 without removing the light-shielding film pattern 2a and the second thin film pattern 5a (see FIG. 1(f)), it may be used as a photomask. The light-shielding film pattern 2a and the second thin film pattern 5a formed thereon serve as light-shielding patterns.

Further, in this embodiment, the light-shielding film 2 is made of molybdenum silicide and the second thin film 5 is made of chromium, but the light-shielding film 2 may be made of chromium and the second thin film 5 is made of molybdenum silicide. good.

In this example, the surface area of the light-shielding film pattern 2a formed on the surface of the light-transmitting substrate 1 is larger than the surface area of the light-shielding film 2 that is removed from the surface of the light-transmitting substrate 1 during its life. Although the case has been described above, it goes without saying that the pattern reversal method of the present invention can also be applied to the opposite case.

Furthermore, the pattern reversal method of the present invention can also be applied to the case where a pattern is reversed and formed on a substrate such as a silicon wafer. That is, a first thin film made of silicon oxide is deposited or formed on the surface of a substrate made of silicon,
Next, through the same steps as described in the above example, a negative electron beam resist is applied on the first thin film, and then the negative electron beam resist is exposed and developed to form the first thin film. A resist pattern is formed on the resist pattern, and then a second thin film (e.g., aluminum) that is resistant to etching of the first thin film is deposited on the resist pattern and the exposed first 'a pattern. The second thin film deposited on the resist pattern is peeled off together with the resist pattern to form a second thin film pattern on the second thin film, and then the first thin film is selected using the second near IRJ film pattern as a mask. Alternatively, a pattern of the first thin film can be formed on the entire surface of the work plate by reversing the resist pattern by etching.

〔Effect of the invention〕

According to the pattern reversal method of the present invention, there is no need to invert the electron beam exposure pattern data using a negative electron beam resist, and in particular, the surface area of the first thin film that is removed from the surface of the substrate is When the surface area of the first thin film pattern formed on the surface of the substrate is large, a desired pattern can be formed in a short exposure time.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the process of manufacturing a photomask using a pattern reversal method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a photomask in which a light-shielding film pattern is formed without pattern reversal. It is a sectional view showing a cross section. DESCRIPTION OF SYMBOLS 1... Transparent substrate, 2... Light blocking film, 2a... Light blocking film pattern, 3... Negative electron beam resist, 3a
...Resist pattern, 4...Electron beam, 5...Second thin film, 5a...Second thin film pattern

Claims (3)

[Claims] (1) A first thin film is deposited on one main surface of the substrate, a negative electron beam resist is applied on the first thin film, and then the negative electron beam resist is exposed and developed to form the first thin film. A resist pattern is formed on the thin film, a second thin film having resistance to etching of the first thin film is deposited on the resist pattern and the exposed first thin film, and then a second thin film is deposited on the resist pattern. Peeling the deposited second thin film together with the resist pattern to form a second thin film pattern on the first thin film, then selectively etching the first thin film using the second thin film pattern as a mask, A pattern reversal method comprising forming a pattern made of the first thin film. (2) The pattern reversal method according to claim (1), wherein the substrate is made of a light-transmitting substrate, and the first thin film is made of a light-shielding film. (3) The pattern reversal method according to claim (1) or (2), wherein the first thin film is made of molybdenum silicide, and the second thin film is made of chromium or aluminum.