KR20100106853A - Blank mask and manufacture method thereof - Google Patents

Abstract

PURPOSE: A blank mask and a manufacturing method thereof are provided to form the pattern of excellent critical dimension accuracy by restraining the neutralization reaction of the strong acid by oxidizing the surface of a reflection prevention layer using sulfur and hydrogen peroxide. CONSTITUTION: A light-shielding layer(520) is formed by using the reactive sputtering method on the top of a transparent substrate(510). A reflection prevention layer(530) of basic is formed on the top of the light-shielding layer using the reactive sputtering method. A reflection prevention layer(531) which is oxidized by implementing the surface process on the reflection prevention layer is formed.

Description

Blank mask and its manufacturing method {BLANK MASK AND MANUFACTURE METHOD THEREOF}

The present invention relates to a blank mask composed of a surface-modified antireflection film and a method of manufacturing the same.

In general, semiconductor integrated circuits such as ICs, LSIs, VLSIs, and the like, are coated with a resist on a substrate, such as a silicon (Si) wafer, to include lithography including exposure, development, etching, doping, and deposition. ) Is produced by repeating the process.

As semiconductor devices are highly integrated, all design rules used in semiconductor devices tend to be reduced, and the critical dimension precision of the photomask that is the original of semiconductor integrated circuits is also high. There is a tendency to be required.

In order to manufacture a photomask requiring high precision, the photomask may be manufactured through a blank mask having a high quality capable of manufacturing a high precision photomask.

1 is a schematic view showing a cross section of a blank mask manufactured by a conventional method, FIG. 2 is a schematic view showing a cross section of a photomask manufactured by a conventional method, and FIG. 3 is an exposure process for explaining a conventional problem. 4A is a schematic diagram showing a phenomenon of time, and FIG. 4A is a schematic diagram showing a footing phenomenon for explaining a conventional problem, and FIGS. 4B and 4C are SEM photographs illustrating a scum phenomenon for explaining a conventional problem.

As shown in FIG. 1, the conventional blank mask 10 has a structure in which a light shielding film 12, an antireflection film 13, and a resist film 14 are sequentially stacked on a transparent substrate 11.

Typically, the light shielding 12 film and the antireflection film 13 include a chromium-based metal, and in particular, the antireflection film is composed of chromium oxynitride (CrON), chromium carbide oxynitride (CrCON), or the like containing a basic substance. .

As the resist for forming a resist film, a chemically amplified resist is used to fabricate a high-precision photomask. The chemically amplified resist consists of an alkali-soluble resin and a photo acid generator. A strong acid (H +) is formed from the photoacid generator by an exposure process of a photomask, and the strong acid is post-exposure baked. The thermal energy of (Post Exposure Bake) acts as a catalyst, resulting in a chain of strong acid diffusion and decomposition reactions to form a pattern of high resolution.

Referring to FIG. 2, the photomask 20 selectively exposes a resist pattern on a blank mask to a predetermined pattern, and then performs a post exposure bake. The light shielding pattern 22 is formed on the transparent substrate 21 through development and etching. ) And the photomask 20 forming the anti-reflection film pattern 23 may be manufactured from the blank mask 10 through the above process.

However, as shown in FIG. 3, the photomask exposure process using the conventional blank mask 10 composed of the basic antireflection film 11 and the resist film 14 formed through the chemically amplified resist prepared by the conventional method is basic. The neutralization of the strong acid generated from the chemically amplified resist occurs by the electrons provided from the anti-reflection film 11.

 First, referring to FIG. 4A, due to this, diffusion and decomposition reactions of strong acids do not occur, thereby causing footing at the interface between the antireflection film and the chemically amplified resist.

Referring to FIG. 4B, a scum that is not developed by the developer due to the diffusion of the strong acid is generated.

In order to observe the scum more clearly, it is possible to clearly observe the phenomenon and wet etching, as shown in FIG. 4C.

Due to the scum generated by the footing or substrate dependency, it is difficult to obtain a desired pattern shape, and there is a problem in that it is impossible to manufacture a photomask having a critical dimension of high precision.

Therefore, the technical problem to be solved by the present invention is to perform a chemical treatment on the anti-reflection film to form a resist pattern without footing during the photomask process by using a blank mask composed of a resist film formed through a chemically amplified resist to achieve high precision. It is to provide a blank mask and a photomask which can have a critical dimension and a method of manufacturing the same.

In addition, the technical problem to be solved by the present invention is to provide a method for producing a high-performance blank mask that does not generate scum by performing a heat treatment such as a rapid heat treatment device on the anti-reflection film on the anti-reflection film.

In addition, the technical problem to be solved by the present invention is to provide a high-quality blank mask and a method of manufacturing the same, which does not occur scum and footing of the chemically amplified resist by applying a light shielding film and an anti-reflection film of a variety of new materials.

In the blank mask fabrication method according to an aspect of the present invention, in the blank mask fabrication method formed by laminating in order of a transparent substrate, a light shielding film, an antireflection film, and a resist film, the light shielding film on the top of the transparent substrate made of quartz is formed of chromium nitride. Forming (CrN) using a reactive sputtering method; Forming a basic anti-reflection film on top of the light shielding film using chromium oxynitride (CrON) using a reactive sputtering method; Forming a oxidized antireflection film by subjecting the basic antireflection film to a solution of sulfuric acid and hydrogen peroxide at a ratio of 5: 1 by using a dipping method for 20 minutes at 90 ° C .; Forming a oxidized and HMDS vapor primed antireflection film by subjecting the oxidized antireflection film to hexamethyllyysilane (HMDS) by vapor priming; And forming a resist film by spin coating a chemically amplified resist on top of the oxidized and HMD vapor-primed anti-reflective film, followed by soft baking at 120 ° C. for 20 minutes.

The light blocking film or the anti-reflection film of the blank mask manufacturing method according to the above characteristics may generate scum by using at least one of chromium (Cr), tantalum (Ta), tungsten (W), titanium (Ti), and aluminum (Al). It is characterized by preventing.

The light blocking film or the anti-reflection film of the blank mask manufacturing method according to the above-mentioned feature has at least one of transition metal, silicon, and silicide, and the light blocking film or the anti-reflection film is nitrided, oxidized, carbonized, nitrided, nitrided, oxidized, or oxidized. It is characterized in that it is in the form of at least one of carbonization and oxynitride carbide.

The thickness of the light blocking film or the anti-reflection film of the blank mask manufacturing method according to the above feature is characterized in that the range of 700 to 1200A.

The concentration of the volatile organic compound impurities on the surface of the light shielding or antireflection film of the blank mask manufacturing method according to the above characteristics is 300 ppb or less, and the concentration of the ionic impurities is 300 ppb or less.

The optical density of the light shielding film or the anti-reflection film of the blank mask manufacturing method according to the above feature is characterized in that between 2.5 to 3.5 at the exposure wavelength.

The reflectance of the light shielding film or the anti-reflection film of the blank mask manufacturing method according to the above feature is characterized by being 20% or less at an exposure wavelength.

The blank mask according to another feature of the present invention is characterized in that the blank mask manufactured by the blank mask manufacturing method.

According to this aspect of the present invention,

The present invention suppresses the neutralization reaction of the strong acid generated from the chemically amplified resist by oxidizing the surface of the antireflection film by using sulfuric acid or hydrogen peroxide, thereby smoothing decomposition and diffusion of strong acid at the interface of the antireflection film and the resist film, resulting in footing. It is possible to manufacture a high quality photomask having excellent dimensional accuracy by minimizing the

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

5 is a flowchart showing a blank mask manufacturing method according to the present invention, Figure 6 is a schematic view showing a cross section of a photomask manufactured by a blank mask according to the present invention, Figure 7 is observed by a blank mask according to the present invention SEM image showing the scum, Figure 8 is a SEM photograph of the scum observed by Comparative Examples 1 to 2 of the present invention, Figure 9 is a SEM photograph of the scum observed by Examples 2 to 3 of the present invention 10 is an SEM photograph of scum observed by Example 10 of the present invention.

(Example 1)

As shown in FIG. 5, in the blank mask manufacturing method according to the present invention, reactive sputtering of chromium nitride (CrN) is performed on the light shielding film 520 on the transparent substrate 510 formed of quartz. Form using the method. At this time, the light shielding film 520 is formed to a thickness of 750A.

Subsequently, a basic anti-reflection film 530 is formed on the light blocking film 520 by using a reactive sputtering method. At this time, the anti-reflection film 530 is formed to a thickness of 200 A.

Subsequently, the basic anti-reflection film 530 is surface-treated at 90 ° C. for 20 minutes using a dipping method to a solution containing sulfuric acid and hydrogen peroxide at a ratio of 5: 1 to an oxidized anti-reflection film 531. Form.

At this time, the surface state of chromium oxynitride (CrON), which is a basic substance, is increased due to sulfuric acid and hydrogen peroxide, and the ratio of oxygen is increased or complete oxidation occurs on the surface causing chromium oxynitride and hydrogen peroxide. Since the surface state of the polymer was hardly left in the basic substance, the neutralization reaction of the strong acid generated during the resist patterning process of the photomask did not occur, and thus the decomposition and diffusion reaction of the strong acid at the interface of the anti-reflection film 531 and the resist film 540 occurred. Actively generated, no footing occurs in the resist patterning process.

Subsequently, oxidized antireflection film 531 is treated with hexamethyllisilane (hereinafter referred to as “HMDS”) to vapor priming to form an oxidized and HMDS vapor priming antireflection film 532. At this time, argon (Ar) gas was used to move the HMDS vapor, and the temperature of the hot plate (Hot-Plate) was 100 ° C. and HMDS vapor frying was performed for 20 seconds.

Finally, after forming the resist film 540 by spin coating a chemically amplified resist on top of the oxidized and HMD vapor-primed anti-reflection film 532, soft bake at 120 ° C. for 20 minutes. At this time, the resist film is formed to a thickness of 4000 A.

6 is a photo having a light shielding film pattern 620 and an antireflection film pattern 630 on a transparent substrate 610 finally through exposure, post-exposure bake, development, and etching of the blank mask manufactured by the above-described manufacturing method. The mask 600 is manufactured.

Referring to FIG. 7, the SEM measurement of the photomask pattern confirmed that a CAR pattern without scum was possible.

Therefore, according to the present invention, as the surface treatment is performed using a solution in which sulfuric acid and hydrogen peroxide are properly mixed on the surface of the anti-reflection film, it is possible to secure a process that does not generate scum during the CAR process, thereby preparing a photomask having excellent quality. It could be confirmed that the high quality semiconductor device can be manufactured.

(Examples 2 and 3 and Comparative Example 1 and Comparative Example 3)

Examples 2 to 3 and Comparative Examples 1 to 2 according to the present invention relate to a blank mask in which scum does not occur by applying a rapid heat treatment apparatus to the antireflection film surface.

First, a chromium-based light shielding film and an antireflection film were formed on the transparent substrate in the same process as in Example 1.

Next, a heat treatment process under various conditions was performed on the surface of the anti-reflection film through a rapid heat treatment apparatus, and the conditions thereof are shown in Table 1 below.

As shown in Table 1 above, after the heat treatment process was performed on the anti-reflection film through a rapid heat treatment apparatus at various temperature ranges, surface modification was performed by applying the same conditions as in Example 1 to the HMDS process.

Next, a chemically amplified resist was formed to a thickness of 3000 GPa to manufacture a blank mask.

Next, after the application of the photomask manufacturing process, which is a conventionally applied photomask manufacturing process (PEB), development, and wet etching, the generation of scum was confirmed through SEM measurement.

In the case of Comparative Examples 1 and 2 it was confirmed that scum occurs as shown in FIG. On the other hand, in the case of Examples 2 to 3, it was confirmed that scum does not occur. It can be seen that the condition that scum does not occur is set by the temperature process range of the rapid heat treatment apparatus.

(Example 4)

This Example 4 and Comparative Example 3 is a result of analyzing the amount of impurities generated in the metal thin film by treating sulfuric acid and hydrogen peroxide solution on the surface of the anti-reflection film.

The impurity levels of the metal thin films of Example 4 and Comparative Example 3, which were treated with sulfuric acid and hydrogen peroxide after forming a chromium-based light shielding film and an antireflection film on the transparent substrate as in Example 1, were determined by ICP / AES and Impurity analysis was performed through ICP / Mass.

The analysis conditions are as follows.

Source: Argon Plasma (6000K)

Spectral Range: 167-782 nm

Detection Limit: 10 ppb

In Example 4 subjected to sulfuric acid and hydrogen peroxide water treatment as shown in Table 2, the total amount of impurities was detected as 41 ppb. However, in Comparative Example 3, which was not subjected to treatment, the total amount of impurities was detected as 227 ppb, and in particular, the amount of Mg was detected as 75 ppb, the highest amount.

Therefore, as in the results of Example 4 and Comparative Example 3, as the sulfuric acid and the hydrogen peroxide solution is treated, the impurity concentration on the surface of the antireflection film is determined, and the scum generation amount difference of the chemically amplified resist is generated according to the impurity concentration. This suggests that the diffusion of strong acids, which act as patterns for chemically amplified resists, is hampered by the concentration of impurities, and especially scums are likely to occur as the diffusion of strong acids occurs actively on the surface of the chromium thin film. .

Therefore, by treating sulfuric acid and hydrogen peroxide water, it is possible to manufacture a blank mask having a high quality without scum being generated, thereby making it possible to manufacture a blank mask having a high quality.

(Example 5 to Example 10)

In the following Examples 5 to 10 is the result of measuring the concentration of volatile organic compounds and ions in the rapid heat treatment process.

First, the light shielding film and the anti-reflection film were formed on the transparent substrate in the same manner as in Example 1, and then the rapid heat treatment was performed. The rapid heat treatment conditions are as shown in Table 3 below.

Referring to Table 3 above, a rapid heat treatment step of 10 to 30 minutes was performed at a temperature of 500 to 600 degrees. Next, the concentrations of volatile organic compounds and ions in the rapid heat treatment process were measured by GC / MS and IC analysis.

Gas Chromatography / Mass Spectroscopy (GC / MS)

Temperature room temperature ~ 450 degrees

Column: Si Coated Column

Carrier Gas: N2

Mass: Quadruple Mass

In the case of GC / MS, the analysis was carried out through the above conditions, and the pretreatment condition for the analysis was to heat the blank mask in a sealed quartz bath at 85 ° C. for 60 minutes in an oven to adsorb organic compounds to the TENAX Tube. Was carried out.

Next, in the case of IC, a blank mask is put into a sealed quartz bath, 150 ml of ultrapure water is added, and heating is performed at 85 degrees for 60 minutes. After adsorption of ions to DI, the ions are adsorbed and analyzed for DI. It was. And the analysis results for volatile organic compounds and ions are shown in Table 4 below.

[Table 4] shows the results of organic compounds and ionic impurities according to the rapid heat treatment process. As a result, it can be seen that the concentration of organic compound impurities and ionic impurities decreases as the temperature of the rapid heat treatment process increases and the time increases.

10 is a SEM photograph of the scum observed by Example 10 of the present invention.

Next, referring to FIG. 10, the blank mask manufactured according to Example 10 was subjected to a conventional photomask manufacturing process, and then SEM measurement was performed on the pattern to observe the presence of scum. Observations show that a significant amount of scum is removed. Therefore, it can be seen that scum control is possible through temperature and time control, which is a rapid heat treatment process variable, and thus it is possible to manufacture a photomask having high quality.

(Examples 11 to 15 and Comparative Examples 3 to 5)

Examples 11 to 15 and Comparative Examples 3 to 5 show results of scum generation through various materials of the light shielding film and the anti-reflection film.

First, the light-shielding film and the anti-reflection film were deposited through various thin films through Reactive Sputtering, which is the same method as in Example 1. In this case, the light shielding film and the antireflection film were applied to the same series of materials in the light shielding film and the antireflection film in order to see the effect according to the material. In the case of the optical film density, it has 3.0 at an exposure wavelength of 365 nm, has a thickness of 800 to 1000 kHz, and has a reflectance of 10 to 15% at an exposure wavelength of 365 nm in the case of reflectance. And the formation of the thin film material according to the detailed examples and comparative examples are as shown in Table 5 below.

As shown in [Table 5], the light shielding film and the anti-reflection film material were formed according to various materials. After the HMDS treatment was carried out in the same manner as in Example 1, a chemically amplified resist was formed to a thickness of 3000 GPa to manufacture a blank mask.

Next, an exposure, PEB, development, and wet etching processes, which are conventional photomask manufacturing processes, were performed to observe scum generation tendencies according to materials.

As a result, no scum was observed in Cr, Ta, W, Ti, and Al corresponding to Examples 11 to 15, and scum was generated in Ni, Fe, and Ce corresponding to Comparative Examples 3 to 5. Therefore, it can be seen that the scum generation tendency is also affected by the light shielding film and the antireflection film material. It is believed that this is because the diffusion of the strong acid generated from the chemically amplified resist into the antireflection film depends on the type of material. Therefore, it can be seen that through the above embodiment, a high quality blank mask without scum can be manufactured.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of course, this is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the equivalents as well as the claims to be described later.

1 is a schematic view showing a cross section of a blank mask manufactured by a conventional method.

2 is a schematic view showing a cross section of a photomask manufactured by a conventional method.

3 is a schematic view showing a phenomenon at the time of an exposure process for explaining a conventional problem.

4A is a schematic diagram showing a footing phenomenon for explaining a conventional problem.

4B and 4C are SEM images of scum phenomena for explaining a conventional problem.

5 is a flowchart illustrating a blank mask manufacturing method according to the present invention.

6 is a schematic view showing a cross section of a photomask manufactured by a blank mask according to the present invention.

7 is a SEM photograph showing the scum observed by the blank mask according to the present invention.

8 is an SEM photograph of scum observed by Comparative Examples 1 to 2 of the present invention.

9 is a SEM photograph of the scum observed by Examples 2 to 3 of the present invention.

10 is a SEM photograph of the scum observed by Example 10 of the present invention.

<Brief description of the main parts of the drawing>

500: blank mask 510, 610: transparent substrate

520: Light shielding film 530: Antireflection film

531: oxidized antireflection film

532: Anti-reflective film with oxidation and HMDS vapor primed

540: resist film 600: photomask

620: light shielding film pattern 630: antireflection film pattern

Claims (8)

In the blank mask manufacturing method formed by laminating in order of a transparent substrate, a light shielding film, an antireflection film, and a resist film, Forming chromium nitride (CrN) using a reactive sputtering method on the light shielding film on the transparent substrate formed of quartz; Forming a basic anti-reflection film on top of the light shielding film using chromium oxynitride (CrON) using a reactive sputtering method; Forming a oxidized antireflection film by subjecting the basic antireflection film to a solution mixed with sulfuric acid and hydrogen peroxide at a ratio of 5: 1 by using a dipping method for 20 minutes at 90 ° C .; Forming a oxidized and HMDS vapor primed antireflection film by subjecting the oxidized antireflection film to hexamethyllyysilane (HMDS) by vapor priming; And And forming a resist film on the oxidized and HMD vapor-primed anti-reflection film by spin coating a chemically amplified resist, followed by soft baking at 120 ° C. for 20 minutes. The method of claim 1, The light shielding film or the anti-reflection film is a blank mask manufacturing, characterized in that to prevent the occurrence of scum by using at least one of chromium (Cr), tantalum (Ta), tungsten (W), titanium (Ti), and aluminum (Al). Way. The method of claim 1, The light shielding film or the antireflection film has at least one of transition metal, silicon, and silicide as a main component, The light shielding film or the anti-reflection film is a blank mask manufacturing method, characterized in that at least any one of the form of nitriding, oxidation, carbonization, nitriding, nitriding, oxidative carbonization, and oxynitride carbide. The method of claim 1, The thickness of the light shielding film or the anti-reflection film is a blank mask manufacturing method, characterized in that in the range of 700 to 1200A. The method of claim 1, A method of manufacturing a blank mask, wherein the concentration of volatile organic compound impurities on the surface of the light shielding or antireflection film is 300 ppb or less, and the concentration of ionic impurities is 300 ppb or less. According to claim 1, And a light density of the light shielding film or the antireflection film is between 2.5 and 3.5 at an exposure wavelength. According to claim 1, The reflectance of the light shielding film or the anti-reflection film is 20% or less at an exposure wavelength. The blank mask manufactured by the blank mask manufacturing method of Claims 1-7.

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