KR20080033108A - Method for manufacturing photomask - Google Patents

Abstract

A method for manufacturing a photomask is provided to minimize the generation of gas accompanied by wet etching, by setting a molar ratio of fluorine compound to oxidizing agent within etchant at a ratio that prevents pattern defects on a semi-transmissive film and/or a light shielding film. A photomask is manufactured by patterning a light shielding film(18) and a semi-transmissive film(17) of a mask blank(20) which comprises the semi-transmissive film capable of adjusting transmissivity to exposure light, and consisting a material containing metal and silicon, and the light shielding film shielding the exposure light that are successively formed on a light-transmissive substrate(16). The patterning of the semi-transmissive film is conducted by wet etching using etchant containing at least one fluorine compound selected one of hydrofluoric acid, hydrofluosilicic acid, and ammonium hydrogen fluoride, and at least one oxidizing agent selected one of hydrogen peroxide, nitride, and sulfuric acid. The etchant has a molar ratio of fluorine compound to oxidizing agent, to be able to prevent generation of pattern defects due to gas accompanied by wet etching.

Description

Manufacturing method of photomask {METHOD FOR MANUFACTURING PHOTOMASK}

TECHNICAL FIELD This invention relates to the manufacturing method of a photomask. Specifically, It is related with the manufacturing method of the photomask used when manufacturing an FPD device.

Recently, in the field of large size FPD masks, attempts have been made to reduce the number of masks by using a gray tone mask having a semi-transmissive region (so-called gray tone portion) (Monthly FPD Intelligence, p. 31-35, 1999). May (Non Patent Literature 1)).

Here, as shown in FIGS. 3 (1) and 4 (1), the gray tone mask includes a light shielding portion 1, a transparent portion 2, and gray as a semi-transmissive region on a transparent substrate. It has a ton part 3. The gray tone part 3 has a function of adjusting the transmission amount with respect to the exposure light, and for example, as shown in Fig. 3 (1), a semi-transmissive film (half transmissive film) 3a 'for a gray tone mask. ), Or as shown in (1) of FIG. 4, the fine light shielding pattern 3a and the fine transmissive portion 3b below the resolution limit of the grayscale mask (a large FPD exposure machine using the gray tone mask). ), The amount of exposure of the exposure light passing through these areas is reduced, the amount of irradiation by this area is reduced, and the film thickness after development of the photoresist corresponding to the area is controlled to a desired value. It is formed for the purpose.

In the case where the large-scale gray tone mask is mounted on a large-scale exposure apparatus of a mirror projection method or a lens projection method using a lens, the exposure light passing through the gray tone part 3 becomes insufficient in overall exposure amount. The positive photoresist exposed through 3) remains on the substrate only as the film thickness becomes thinner. That is, since the difference in the solubility with respect to a developing solution arises in the part corresponding to the normal light-shielding part 1 and the part corresponding to the gray-tone part 3 by a difference in an exposure amount, the resist shape after image development is shown in FIG. 2) and part 2 'corresponding to the normal light shielding part 1, for example, about 1 micrometer and the part 3' corresponding to the gray tone part 3 as shown to (2) of FIG. For example, the portion corresponding to about 0.4 to 0.5 mu m and the transmissive portion 2 becomes the portion 2 'having no resist. Then, the first etching of the substrate to be processed is performed in the portion 2 'without the resist, and the resist of the thin portion 3' corresponding to the gray tone portion 3 is removed by ashing or the like, and the second etching is performed in this portion. By performing the process, one mask is performed for two conventional masks, and the number of masks is reduced.

By the way, the mask for LSI for manufacturing semiconductor devices, such as a microprocessor, a semiconductor memory, and a system LSI, is relatively small at a maximum of 6 inches each, and is mounted in the reduction projection exposure apparatus by a stepper (short step exposure) system. It is often used.

Moreover, in the small mask blank for manufacturing the mask for LSI, since high etching precision is needed, patterning of the thin film formed on the mask blank by dry etching is performed.

In contrast, a large-sized mask for an FPD (flat panel display) is relatively large in size from 330 mm x 450 mm to 1220 mm x 1400 mm, and a lens using a mirror projection (equivalent projection exposure by scanning exposure method) or a lens. It is often mounted and used in a projection type exposure apparatus.

In addition, in the manufacture of a large sized mask for FPD, it is difficult to manufacture a large dry etching apparatus, and even if manufactured, it is technically difficult to etch very expensive and uniformly. For this reason, in the large-sized mask blank for manufacturing the large-sized mask for FPD, wet etching using the etching liquid is adopted by focusing on the cost surface and throughput rather than the dry etching by focusing on the high etching accuracy like the LSI mask. Patterning of the thin film formed on the mask blank is performed.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly researched and developed about the wet etching of the metal silicide type semi-transmissive film which consists of a material containing a metal and silicon (Si) about the large mask blank for FPD and the large photomask for FPD.

As a result, the following were found.

When etching metal silicide films, such as molybdenum silicide, the mixed solution of hydrofluoric acid + nitric acid is used normally.

However, in the reaction according to the etching described above, we found out that there are N0 ₂ problem that harmful gas is generated in large quantities (the first problem).

The present inventors inferred the reason from the viewpoint of a reaction formula.

Below, the mechanism of the guessed reaction is shown.

From Scheme 1, Scheme 2,

Also,

From Scheme 3 and Scheme 4,

Importantly in the above Reaction Schemes 1 to 5, the function as an acid for dissolving silicon and molybdenum is hydrofluoric acid (Scheme 2, Scheme 4), the nitric acid is not effective as an acid for dissolving silicon and molybdenum and to oxidize silicon It is only necessary for this purpose, and the reaction as an oxidizing agent is used (Scheme 1).

As described above, in the etching schemes 1 to 5 of the molybdenum silicide by hydrofluoric acid + nitric acid, highly toxic hydrofluoric acid (toxic) and nitric acid (polar) are used, and further, toxic and corrosive nitrogen dioxide (N0 ₂ ) There is a problem that gas is generated as a gas. In addition, in the reaction by hydrofluoric acid + nitric acid, there is a problem (first problem) that harmful gases such as NO ₂ are generated in a large amount.

Therefore, the present inventors have studied using hydrogen peroxide (H ₂ O ₂ ) as an oxidant instead of nitric acid and ammonium hydrogen fluoride (NH ₄ FHF) instead of hydrofluoric acid based on past research results. (Patent Document 1: Japanese Patent Laid-Open No. 62-218585). This makes it possible to dissolve silicon and molybdenum without the use of highly toxic hydrofluoric acid and nitric acid, and without toxic and corrosive nitrogen dioxide (NO ₂ ) gas.

In reaction by said etching, generation | occurrence | production of a gas and generation | occurrence | production of the bubble accompanying it can be suppressed significantly compared with said reaction formula 1-reaction formula 5 by said hydrofluoric acid + nitric acid. However, it was found that in the reaction by the above etching, there was still the generation of gas and the accompanying bubbles (bubble of relatively large size that can be observed and confirmed).

The present inventors inferred the reason from the viewpoint of a reaction formula.

Below, the mechanism of the guessed reaction is shown.

From Scheme 6, Scheme 7,

Also,

Therefore, from Scheme 8 and Scheme 9,

Naturally, the hydrogen of Scheme 10 can be oxidized with nitric acid and replaced with water as shown in the following formula, but the generation of nitrogen dioxide (N0 ₂ ) gas increases by that much.

3H ₂ + 6HNO ₃ → 6H ₂ 0 + 6N0 ₂ ↑

As described above, in the etching schemes 6 to 10 of the molybdenum silicide by ammonium hydrogen fluoride + hydrogen peroxide, the generation of gas and the accompanying bubbles are significantly suppressed compared to the schemes 1 to 5 by the hydrofluoric acid + nitric acid. It can be seen that. However, it can be seen that in the etching schemes 6 to 10 of the molybdenum silicide by ammonium bifluoride + hydrogen peroxide, generation of gas and accompanying bubbles (H ₂ ) still occur.

In the etching reaction of molybdenum silicide by ammonium hydrogen fluoride + hydrogen peroxide as described above, the inventors of the present invention show that when bubbles are generated and bubbles (H ₂ ) accompanying them are generated, the bubbles are generated from the film surface and grown. (FIG. 2), therefore, bubbles are attached to the portion where the pattern of the molybdenum silicide film should not be formed, and the pattern of the semi-transmissive film by the gas (H _2, etc.) generated due to wet etching of the semi-transmissive film, such as a defect in the film remaining. It became clear that the location which a defect generate | occur | produces (2nd subject). This second problem is largely affected when the film thickness is as thin as about 10 to 100 angstroms, such as a semi-transmissive film in a gray tone mask.

The inventors of the present invention further showed that the etching solution of ammonium hydrogen fluoride + hydrogen peroxide is a gas generated by wet etching of the semi-transmissive film by using a molar ratio X: Y of ammonium hydrogen fluoride and hydrogen peroxide in the etching solution solution as described below. Setting the molar ratio to prevent the pattern defect of the semi-translucent film by (H _2, etc.) is effective as a countermeasure for the second problem, and has a molar ratio x: y in which the amount of gas generated by etching is minimized. By setting it, the generation | occurrence | production of gas can be suppressed as much as possible, and it was clear that it was very effective as a countermeasure of the said 2nd subject. However, even if the molar ratio of the etching solution is set in this way, hydrogen peroxide is easy to decompose, and therefore, there is a problem that oxygen gas (0 ₂ ) is likely to be generated, and thus it is difficult to completely suppress the generation of gas (third problem). ).

In addition, when forming a light shielding film on a metal silicide film like a gray mask, depending on the material of the light shielding film, oxygen gas (0 ₂ ) generated during wet etching of the metal silicide film may have seen the light shielding film pattern in cross section. The cross-sectional shape of the light shielding film is changed by changing the etching rate when the light shielding film is etched by entering the upper surface or the side surface of the light shielding film pattern at the time, or the optical properties (reflectance or optical density) of the light shielding film are changed. It has been found that a portion where a pattern defect of the light-shielding film is generated due to a gas (0 _2, etc.) generated in accordance with the wet etching of the translucent film occurs (fourth problem).

SUMMARY OF THE INVENTION An object of the present application is to solve the above-described problems, and a method of manufacturing a photomask capable of preventing pattern defects of the semi-transmissive film and / or the light-shielding film caused by a gas generated by wet etching of the semi-translucent film. To provide.

The method of this invention has the following structures.

(Configuration 1)

On the light-transmissive substrate, the light-shielding film and the semi-transmissive film made of a material containing a metal and silicon and a light-shielding film for shielding exposure light are sequentially formed on the light-shielding film. As a method of manufacturing a photomask in which the semi-transmissive film is patterned to produce a photomask,

The semi-transmissive film is patterned by wet etching using an etching solution containing at least one fluorine compound selected from hydrofluoric acid, hydrofluoric acid and ammonium bifluoride, and at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid. ,

The etching solution is an etching solution in which the molar ratio of the fluorine compound and the oxidant in the etching solution is set to a molar ratio that prevents pattern defects caused by the gas generated with wet etching.

(Configuration 2)

On the light-transmissive substrate, the light-shielding film and the semi-transmissive film made of a material containing a metal and silicon and a light-shielding film for shielding exposure light are sequentially formed on the light-shielding film. As a method of manufacturing a photomask in which the semi-transmissive film is patterned to produce a photomask,

The patterning of the translucent film includes at least one fluorine compound selected from hydrofluoric acid, hydrogen silicate mass and ammonium hydrogen fluoride, at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid, and a defoamer or antifoaming agent. It performs by wet etching using etching liquid, The manufacturing method of the photomask characterized by the above-mentioned.

(Configuration 3)

The molar ratio of the fluorine compound and the oxidizing agent in the etching solution is a molar ratio in which the amount of gas generated by wet etching is minimized.

(Configuration 4)

The film thickness of the said translucent film is 10-100 angstroms, The manufacturing method of any one of the structures 1-3 characterized by the above-mentioned.

(Configuration 5)

Said photomask is a photomask for manufacturing an FPD device, The manufacturing method of any one of the structures 1-4 characterized by the above-mentioned.

According to the present invention, the above-mentioned problem can be solved, and the photomask can be prevented from pattern defects of the semi-transmissive film and / or the light-shielding film due to the gas generated by wet etching of the semi-transmissive film. Methods and the like can be provided.

Hereinafter, the present invention will be described in detail.

The present invention has a function of adjusting a transmission amount to exposure light on a light-transmissive substrate, and a mask blank in which a semi-transmissive film made of a material containing metal and silicon and a light shielding film that shields exposure light are sequentially formed. As a manufacturing method of a photomask which patterns the said light-shielding film and the said semi-transmissive film, and manufactures a photomask,

The semi-transmissive film is patterned by wet etching using an etching solution containing at least one fluorine compound selected from hydrofluoric acid, hydrofluoric acid and ammonium bifluoride, and at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid. The etching liquid is characterized by being an etching liquid in which the molar ratio of the fluorine compound and the oxidant in the etching liquid is set to a molar ratio that prevents pattern defects caused by the gas generated with wet etching (Configuration 1).

According to the first aspect of the present invention, the aforementioned problems 1 and 2 can be solved by setting the molar ratio of the fluorine compound and the oxidizing agent in the etching solution to a molar ratio that prevents pattern defects caused by the gas generated with wet etching. And a method for manufacturing a photomask, which can prevent a pattern defect of the semi-translucent film caused by the gas generated in accordance with the wet etching of the semi-translucent film.

In the first aspect of the present invention, the etching liquid in which the molar ratio of the fluorine compound and the oxidant in the etching solution is set to a molar ratio that prevents patterning defects caused by a gas generated by wet etching is a molar ratio of the fluorine compound and the oxidant. And the relationship with the pattern defects due to the gas generated with wet etching is determined by changing the molar ratio, and based on this, the molar ratio can prevent the pattern defects due to the gas generated with the wet etching. It is obtained by setting in molar ratio.

In addition, the etching liquid which set the molar ratio of the said fluorine compound and the said oxidizing agent in the said etching liquid to the molar ratio which prevents the pattern defect by the gas generate | occur | produced with wet etching is simply the molar ratio of the said fluorine compound and the said oxidizing agent. And the relationship between generation of bubbles is obtained by changing the molar ratio, and based on this, the molar ratio is obtained by setting the molar ratio at which no bubbles are generated. In this case, however, it is necessary to confirm whether or not the pattern defect due to the gas generated by the wet etching can be prevented by setting the molar ratio at which no bubbles are generated.

In addition, the molar ratio of the said fluorine compound and the said oxidizing agent in the said etching liquid is not normally set from the viewpoint which prevents the pattern defect by the gas which arises with wet etching, but rather another viewpoint (for example, etching performance) The molar ratio is set from the viewpoint of maintenance. For this reason, the molar ratio of the said fluorine compound and the said oxidant in the said etching liquid is quite different from the molar ratio which normally prevents the pattern defect by the gas which arises with wet etching.

In this 1st invention, it is preferable that the molar ratio of the said fluorine compound and the said oxidizing agent in the said etching liquid is a molar ratio by which the generation amount of the gas which arises with wet etching becomes minimum (the structure 3).

The reason for this is that, by minimizing the amount of gas generated with wet etching (minimum value), it is thought that the pattern defects caused by the gas generated with wet etching can be reduced as much as possible.

In the present invention, the molar ratio of the fluorine compound and the oxidizing agent in which the amount of gas generated due to wet etching is minimized can be determined from the reaction scheme estimated as described above. This is explained as follows.

For example, in the reaction scheme 10, by adding 5 mol of hydrogen peroxide, the generated hydrogen can be oxidized to water. If this is represented by a formula, it will become following Reaction Formula 11.

Here, molybdenum silicide is not necessarily present in the stoichiometric equivalent ratio of MoSi ₂ , and is often in the form of MoSi _x . The reaction formula in this case becomes following reaction formula 12.

However, in Scheme 12, α = 2x + 3.

In the above Reaction Scheme 12, the molar ratio of ammonium hydrogen fluoride and hydrogen peroxide is adjusted to the content ratio (atomic% ratio) of Mo and Si so that the generation (amount) of gas is at a minimum (minimum value) (zero in Reaction Scheme 12). Doing.

That is, when the material of the translucent film is MoSi _x and the etching solution uses hydrogen peroxide (H ₂ O ₂ ) and ammonium hydrogen fluoride (NH ₄ FHF), it is set to a molar ratio of hydrogen peroxide: ammonium bifluoride = 1: 2. Since the generation (amount) of gas becomes minimum (minimum value), it is preferable.

In addition, when the material of the semi-translucent film is MoSi _x and the etching solution uses hydrogen peroxide (H ₂ O ₂ ) and hydrofluoric acid (HF), when the molar ratio of hydrogen peroxide: hydrofluoric acid = 1: 2 is set, generation of gas (amount) ) Is preferred because it is minimum (minimum).

In addition, when the material of the translucent film is MoSi _x and the etching solution uses nitric acid (HNO ₃ ) and hydrofluoric acid (HF), or nitric acid (HNO ₃ ) and ammonium bifluoride, nitric acid: hydrofluoric acid = 1: 1, It is preferable to set the molar ratio of nitric acid: ammonium hydrogen fluoride = 1: 1 because the generation (amount) of gas is minimum (minimum value).

For example, in the case where the thin film material containing the metal M and silicon (Si) is MSi _x (wherein M is a transition metal such as Mo, Ni, W, Zr, Ti, Ta, Cr, and the like) According to 12, the molar ratio (for example, the molar ratio of ammonium hydrogen fluoride and hydrogen peroxide) of the said fluorine compound and the said oxidizing agent is made into the molar ratio whose generation amount of the gas which generate | occur | produces with etching becomes minimum or minimum value.

In the case of MSixZ (where Z is N, C, H, 0, F, etc., and M is a transition metal such as Mo, Ni, W, Zr, Ti, Ta, Cr, or the like) Depending on the type and the type of Z, the addition of Z does not necessarily lead to gas generation. However, when the addition of Z leads to gas generation, the molar ratio of ammonium hydrogen fluoride and hydrogen peroxide is determined in consideration of the content of Z. The molar ratio at which gas is generated is minimum or minimum.

In the first aspect of the present invention, the molar ratio X: Y of the fluorine compound and the oxidant in the etching solution is a molar ratio of the fluorine compound and the oxidant in which the amount of gas generated with wet etching is minimized. In this case, x ± 10%: y ± 10%.

The reason for this is that if it is the said range, the generation amount of the gas which generate | occur | produces with wet etching can be reduced to the minimum. Moreover, even if it is the said range, it is because it is thought that the pattern defect by the gas which arises with wet etching can be substantially prevented.

According to the second aspect of the present invention, a mask blank has a function of adjusting a transmission amount to exposure light on a light-transmissive substrate, and a semi-transmissive film made of a material containing metal and silicon, and a light shielding film that shields exposure light. The method of manufacturing a photomask in which the light-shielding film and the semi-translucent film are patterned therefrom, wherein the patterning of the semi-translucent film is at least one fluorine compound selected from hydrofluoric acid, hydrofluoric acid and ammonium bifluoride. And wet etching using an etching solution containing at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid, and a defoamer or antifoaming agent (constitution 2).

According to the second aspect of the present invention, the problems 1 to 4 described above can be solved, and the pattern defects of the semi-transmissive film and the light-shielding film due to the gas generated by wet etching of the semi-transmissive film can be prevented. The manufacturing method of a mask, etc. can be provided.

Specifically, by using an etching solution composed of a solution containing ammonium hydrogen fluoride, hydrogen peroxide, a defoaming agent or an antifoaming agent, and water, degassing the generated gas or bubbles even when gas is generated or the gas becomes a bubble. Or it can be removed by parcels. As a result, the problem (second problem) of the generation of the pattern defect of the semi-transmissive film by the gas (H _2, etc.) generated with the wet etching reaction of the semi-transmissive film can be solved. Further, it is possible to solve the problem (third problem), and the problem of the occurrence of pattern defects of the light-shielding film formation by it (the fourth problem) of the gas (O _2, etc.) generated at the time of a half transmissive film, wet etching.

It is preferable that this 2nd invention suppresses the influence by generation | occurrence | production of a gas by action of both in combination with this 1st invention. In particular, in the second invention, the molar ratio of the fluorine compound and the oxidant in the etching solution is preferably a molar ratio where the amount of gas generated by wet etching is minimized (constitution 3). As described above, in the case where the etching solution contains a defoaming agent or an antifoaming agent while suppressing the generation of gas by matching the molar ratio of the fluorine compound and the oxidant in the etching solution, a synergistic effect on the effect of the generation of gas can be expected. Moreover, what is necessary is just to contain a trace amount defoamer or antifoamer.

In this 2nd invention, it is preferable that a defoaming agent has the effect | action which can degas | defoam even if generated gas turns into a bubble. The defoamer according to the present invention preferably has a function of penetrating bubbles adsorbed on the substrate surface and adsorption surfaces of the substrate, and preferably has a function of detaching bubbles adsorbed on the substrate surface from the substrate surface.

As a defoaming agent which has such an effect, lauryl alcohol sulfate ester, lauryl alcohol sodium sulfate (sodium lauryl sulfate), etc. are mentioned, for example.

The content of the defoamer, for example, is 10 ^-5 ~10 ^-2 wt% of lauryl alcohol sulfuric acid ester, if the aqueous solution, the etching solution per liter 0.1~2㎖ preferred.

As an antifoamer, what has the effect | action which melt | dissolves (absorb | sucks) a small bubble in a liquid, the effect | rupture of a bubble, etc. is good. In addition, the antifoaming agent should have an effect similar to the surfactant which reduces the adsorption force of the bubble and the film | membrane on a board | substrate, and removes a bubble from a film surface.

Specific antifoaming agents include lower and higher aliphatic alcohols, lower and higher fatty acids, lower and higher aliphatic amides, lower and higher fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene glycerin fatty acid ethers, and polyoxyalkylenes. And antifoaming agents such as silicones.

In this invention, it is also possible to add both a defoaming agent and an antifoamer.

In the said 1st invention or this 2nd invention, it is preferable to set the temperature of etching liquid in the range of 10 degreeC or more and 60 degrees C or less. In the case of less than 10 ° C, the etching rate of the semi-translucent film is slowed down, which leads to poor productivity, which is not preferable. Moreover, when it exceeds 60 degreeC, since the etching rate of a semi-transmissive film becomes high and the pattern dimension precision of the semi-transmissive film pattern to form is worsened, it is unpreferable. As for the temperature range of a preferable etching liquid, 20 degreeC or more and 45 degrees C or less are preferable.

In the first invention or the second invention, as the metal constituting the translucent film made of a material containing metal and silicon, molybdenum (Mo), nickel (Ni), tungsten (W), zirconium (Zr), Titanium (Ti), tantalum (Ta), chromium (Cr), the alloy containing these elements, or the material containing the said element or the said alloy, etc. are mentioned.

Specifically, for example, metal M and silicon (transition metal such as MSi, M: Mo, Ni, W, Zr, Ti, Ta, Cr), oxynitride metal and silicon (MSiON), oxidized carbonized metal And silicon (MSiCO), oxynitride carbonized metal and silicon (MSiCON), oxidized metal and silicon (MSi0), nitrided metal and silicon (MSiN), and the like.

The composition, the film thickness, and the like of the semi-translucent film are set to have a function of adjusting the amount of transmission to the exposure light.

In the first aspect of the present invention or the second aspect of the present invention, the material of the light-shielding film that shields the exposure light includes chromium alone or chromium containing at least one element consisting of oxygen, nitrogen, carbon, and hydrogen (Cr And the like), and the like. Specifically, for example, chromium, chromium nitride, chromium oxide, chromium carbide, chromium fluoride, materials containing at least one thereof, materials containing elements such as hydrogen and helium, and the like Can be mentioned. As a film structure of a light shielding film, it can be set as the single layer and multiple layer structure which consist of the said film material. Moreover, in a different composition, it can be set as the multilayer structure formed in steps and the film structure which changed composition continuously.

In the present invention, dipping, spraying, spraying, and the like can be cited as the wet etching method.

In addition, in the spray method or the wet etching method by the spray method, when etching, the bubble may be rolled up and the bubble may adhere to the surface of the substrate, but according to the second aspect of the present invention, Thereby, the influence by such a bubble can also be avoided.

The manufacturing method of the photomask of this invention is especially effective when the film thickness of the said translucent film is 10-100 angstroms (the structure 4).

The reason for this is that, as described above, the second problem is when the film thickness is as thin as about 10 to 100 angstroms, such as a semi-transmissive film in a gray tone mask, which is an example of a photomask for manufacturing an FPD device. This is because the impact is large.

For this reason, the manufacturing method of the photomask of this invention is especially effective as a manufacturing method of the photomask for manufacturing an FPD device (Configuration 5).

In the manufacturing method of the photomask which concerns on the said 1st invention or this 2nd invention, the said light-shielding film and the said translucent film are patterned from the mask blank in which the said semi-transmissive film and the said light-shielding film were formed sequentially on the translucent board | substrate. , A photomask is prepared.

A method of manufacturing such a photomask will be described below with reference to FIG. 1, which shows an example of a manufacturing process for manufacturing a gray tone mask that is an example of a photomask for manufacturing an FPD device.

First, a process of sequentially forming a semi-transmissive film 17 and a light-shielding film 18 on the surface of the translucent substrate 16 is performed to form and prepare a mask blank 20 (FIG. 1A). .

Here, the semi-transmissive film 17 can form a semi-transmissive film made of a material containing metal and silicon, for example, by sputter film formation using a metal silicide-based sputter target containing metal and silicon (Si). have. The film thickness is suitably selected by the transmittance | permeability of the translucent film | membrane required.

Next, the light shielding film 18 is formed of a single layer or a multilayer structure (eg, an antireflection film) by using a reactive sputter using a reactive gas such as nitrogen, oxygen, methane, or carbon dioxide, using, for example, a chromium target. Light-shielding film) can be formed.

These semi-transmissive films 17 and light-shielding films 18 are resistant to the etching of each other in the manufacturing process of the gray tone mask 10. That is, the semi-translucent film 17 is resistant to the etching liquid for chromium. In addition, the light shielding film 18 is resistant to the etching solution for metal silicide.

Next, a resist film (positive resist film or negative resist film) is formed on the light shielding film 18 of the mask blank 20, and the resist film is exposed using an electron beam or a laser drawing apparatus, and the developer is exposed. Is developed to form the first resist pattern 21 (FIG. 1B).

This 1st resist pattern 21 is formed in the shape which makes the light transmission part 14 of the manufactured gray tone mask 10 into an opening area | region. As the resist for forming the first resist pattern 21, a novolac resist can be used.

The mask blank 20 in which this 1st resist pattern 21 was formed was immersed in the etching liquid for chromium, and light-shielding of the mask blank 20 was carried out using this etching liquid for chromium, using the 1st resist pattern 21 as a mask. The film formation 18 is wet etched (FIG. 1C). By this etching, the light shielding film pattern 22 is formed in the light shielding film 18. In addition, the semi-translucent film 17 is not etched in that it is resistant to the etching liquid for chromium. Moreover, since the resist which comprises the 1st resist pattern 21 has favorable adhesiveness with the light shielding film 18, it is not peeled off by the etching liquid for chromium.

After formation of the light shielding film pattern 22, the first resist pattern 21 remaining on the light shielding film pattern 22 is peeled off (FIG. 1D). After peeling the first resist pattern 21, the mask blank 20 on which the light shielding film pattern 22 is formed is immersed in an etching solution for metal silicide, and the light shielding film pattern 22 is formed using the etching solution for metal silicide. The semi-transmissive film 17 is wet-etched using a mask to form the semi-transmissive film pattern 23 (FIG. 1E). The light-transmitting portion 14 is formed by the light-shielding film pattern 22 and the semi-transmissive film pattern 23.

The etching solution for metal silicide contains at least one fluorine compound selected from hydrofluoric acid, hydroperoxide and ammonium bifluoride, and at least one oxidizing agent selected from hydrogen fluoride, nitric acid and sulfuric acid.

In the present invention, the molar ratio of the fluorine compound and the oxidant in the etching solution for the metal silicide is set to a molar ratio that prevents pattern defects caused by the gas generated with wet etching, or the molar ratio is generated with wet etching. The molar ratio can be set to the minimum amount of gas to be produced. Moreover, the etching liquid containing a defoaming agent or an antifoamer in these etching liquid can also be used.

In addition, the light shielding film 18 is not etched to be resistant to the etching solution for metal silicide. Since the semi-transmissive film 17 is etched with the etching solution for metal silicide using the light-shielding film pattern 22 which consists of this light-shielding film 18 as an etching mask, the resist which comprises the said 1st resist pattern 21 and the said The etching solution for metal silicides does not react chemically and generates foreign substances composed of fluoride organic substances.

After the semi-transmissive film pattern 23 is formed as described above, a step of removing the desired portion of the light-shielding film 18 constituting the light-shielding film pattern 22 is performed. That is, a resist film is formed on the light shielding film pattern 22 and the light transmissive substrate 16, and the resist film is exposed and developed as described above to form a second resist pattern 24 (FIG. 1F). )). The second resist pattern 24 is formed in a shape in which the gray tone portion 15 is an opening region. Next, the light shielding film 18 which comprises the light shielding film pattern 22 is further wet-etched using the said 2nd resist pattern 24 as a mask (FIG. 1G).

Thereafter, the remaining second resist pattern 24 is peeled off, and the light shielding portion 13 in which the gray tone portion 15 formed of the semitransparent film 17, the light shielding film 18, and the semi-transmissive film 17 are laminated is laminated. ), A gray tone mask 10 having () is manufactured (Fig. 1 (H)).

According to the said manufacture example, the following effects are exhibited from the structure comprised as mentioned above.

In the manufacturing process of the gray tone mask 10, as shown in FIG. 1D, after peeling off the 1st resist pattern 21, the light-transmissive film pattern 22 is used as a mask, and the semi-transmissive film ( 17) (metal silicide film) is etched using an etching solution for metal silicide. From this, the resist of the first resist pattern 21 and the etchant for metal silicide do not chemically react to generate foreign matters. Therefore, the foreign matters are formed on the light-transmissive substrate 16 or the light shielding film pattern 22. It can be reliably prevented from adhering on (13).

In the present invention, substrates such as synthetic quartz, soda lime glass, borosilicate glass, and alkali free glass may be mentioned as the light-transmissive substrate.

In the present invention, mask blanks and masks for manufacturing FPD devices include mask blanks and masks for manufacturing FPD devices, such as LCD (liquid crystal display), plasma display, organic EL (electroluminescence) display, and the like. have.

Here, the mask for manufacturing LCD includes all the masks necessary for manufacturing LCD, for example, TFT (thin film transistor), especially TFT channel part or contact hole part, low temperature polysilicon TFT, color filter, reflecting plate (black matrix), Masks for forming a back and the like are included. Other masks for manufacturing display devices include all masks necessary for manufacturing organic EL (electroluminescence) displays, plasma displays and the like.

Hereinafter, the present invention will be described in more detail based on examples.

(Example 1)

(Preparation of Etching Liquid)

The etching liquid of the translucent film was prepared and prepared as follows.

These aqueous solutions were mixed so that the molar ratio of hydrogen peroxide: ammonium hydrogen fluoride might be 1: 2, and also this was diluted with pure water, and the etching liquid was prepared. At this time, the amount of ammonium hydrogen fluoride was 1 wt% with respect to the total amount of the etching solution after dilution with pure water (100 wt%) (to 0.1 to 20 wt% as ammonium hydrogen fluoride relative to the total amount of etching solution (100 wt%)). ) Diluted. In addition, a 10% solution of lauryl alcohol sulfate ester as a defoamer was mixed with 0.01 wt%.

As an etching liquid of a light-shielding film, HY liquid (made by Haosei Co., Ltd.) which is chromium etching liquid (etch liquid containing 2nd cerium ammonium nitrate and perchloric acid) was prepared.

(Production of mask blanks)

On the large glass substrate (10 mm thick of synthetic quartz (QZ), size 850 mm x 1200 mm), the semi-transmissive film for gray tone mask was formed into a film using the large size inline sputtering apparatus. Specifically, using a target of Mo: Si = 20:80 (atomic% ratio), using Ar as a sputtering gas, a semi-translucent film 17 (MoSi ₄ ; Mo) for a gray tone mask made of molybdenum and silicon : 20 atomic%, Si: 80 atomic%) was formed (see FIG. 1A). At this time, the film thickness was adjusted so that the transmittance | permeability in the range over i line | wire to g line | wire which is a wavelength of an exposure light source may be 60%. At this time, the film thickness of the translucent film was in the range of 10 to 100 angstroms.

Next, the light-shielding film was formed on the semi-transmissive film for the gray tone mask by using a large in-line sputtering device. Specifically, as the light shielding film 18, a chromium nitride film, a chromium carbide oxide film, and a chromium oxynitride film (antireflection layer) were successively formed by the sputtering method sequentially from the substrate side (see Fig. 1A). ). At this time, the film thickness was adjusted so that the optical density in the range over i line | wire to g line | wire which is a wavelength of an exposure light source may be three or more.

Next, on the said light-shielding film, the novolak-type resist film was formed with the film thickness of 10000 angstrom by the rotation coating method.

As described above, a mask blank 20 with a resist film according to Example 1 was obtained (see FIG. 1A).

(Mask making)

Next, a mask was manufactured according to the gray-tone mask manufacturing process of the semi-transmissive film bottom arrangement type shown in FIG. 1 mentioned above. At this time, the etching solution prepared above was used as the etching solution of the semi-translucent film. In addition, the etching liquid of chromium prepared above was used as etching liquid of a light shielding film.

Further, in the above-mentioned mask production process, at the time of half-etching the transparent film, the generation of bubbles of hydrogen (H _2), oxygen (O ₂₎ was observed.

(evaluation)

When the semi-transmissive film pattern formed on the mask obtained above and the light-shielding film pattern were examined, the defect considered to be due to the bubble which arises at the time of wet etching of a translucent film was not confirmed.

Moreover, the cross-sectional shape of the light shielding film pattern was favorable. The reflectance of the antireflection film in the barrier film pattern was not changed before and after the etching process of the semi-transmissive film (see FIGS. 1D and 1E).

(Comparative Example 1)

As an etching solution to which no lauryl alcohol sulfate ester was added, an etching solution without preparing a molar ratio was used as in Example 1, except that it was the same as in Example 1. Specifically, the etching solution under the conditions described in Patent Literature 1 (1 wt% ammonium bifluoride + 4.4 wt% hydrogen peroxide (the molar ratio of hydrogen peroxide to ammonium bifluoride was about 4: 1)) was used.

Further, in the mask making process, at the time of a half transmissive film, wet etching, it was confirmed that generation of the bubbles, such as hydrogen (H _2).

As a result of the evaluation, there were two pattern shots which are thought to be due to bubbles generated during wet etching of the semi-translucent film, and ten films remained in the light transmissive part (a part where the molybdenum silicide film was completely etched away to expose the substrate surface). The thickness is about the same as the film thickness).

(Comparative Example 2)

In Example 1, it carried out similarly to Example 1 except having used the hydrofluoric acid (hydrofluoric acid) + sulfuric acid etching liquid (1 wt% hydrofluoric acid, the molar ratio of hydrofluoric acid: nitric acid is 4: 7).

Further, in the mask making process, at the time of half-etching the transparent film, nitrogen dioxide (N0 ₂₎ the generation of the bubbles, such as was observed in large quantity.

As a result of evaluation, 33 pattern short defects and 21 film | membrane remainders which were thought to be caused by foam were the whole surface.

(Example 2)

In the first embodiment, La is not us added alcohol sulfuric acid ester of an etching solution (hydrogen peroxide, the molar ratio of hydrogen fluoride ammonium was 1: and 2, in a molar ratio, the amount of generation of gas (H ₂₎ generated along with the wet etching is minimum It was similar to Example 1 except having used).

Moreover, in the mask manufacturing process, generation | occurrence | production of the bubble, such as a minute and a trace amount of oxygen, was confirmed at the time of the etching of a translucent film.

Defect is thought to be due to the result of the evaluation, with respect to the semi-light-transmitting film pattern, bubbles generated at the time of semi-translucent film, wet etching (H _2, etc.) was not found.

In addition, the surface of the light-shielding film is an antireflection film sufficiently containing oxygen in the first place, and the surface reflectance variation of the light-shielding film was hardly before and after the etching process of the semi-transmissive film (see FIGS. 1D and 1E). . In addition, even in the etching process of the light shielding film (particularly, (F) and (G) processes in FIG. 1), since the light shielding film contains nitrogen, the effect of oxygen is small and does not affect the etching rate of the light shielding film much. The pattern cross-sectional shape of the light shielding film also did not deteriorate.

(Examples 3 to 4)

In Example 2, the mask was produced like Example 2 except having made the fluorine compound in etching liquid the hydrofluoric acid (hydrofluoric acid), and made the molar ratio of hydrogen peroxide: hydrofluoric acid 1: 2 (Example 3). In Example 2, a mask was prepared in the same manner as in Example 2 except that the oxidizing agent in the etching solution was made of nitric acid and the molar ratio of nitric acid: ammonium hydrogen fluoride was 1: 2 (Example 4).

As a result, in Examples 3 and 4, in the mask manufacturing process, when the semi-transmissive film was etched, the generation of bubbles such as a small amount and a small amount of oxygen was confirmed. The defect considered to be due to the bubble which generate | occur | produces at the time of an etching was not confirmed.

In addition, similarly to Example 1 with respect to the etching liquid of Examples 3 and 4, when the defoaming agent was added, the defect resulting from the foam which arises at the time of wet etching of a translucent film was not confirmed.

(Example 5)

In Example 2, the molar ratio of ammonium hydrogen fluoride: hydrogen peroxide in the etching solution is 2: 1, which is the molar ratio (x: y) of the fluorine compound: oxidant which minimizes the amount of gas generated with wet etching. A mask was produced in the same manner as in Example 2, except that 2.4: 1, which was 10%: x-0.1%. As a result, in the mask manufacturing process, the generation of micro bubbles and traces of oxygen and the like was confirmed during the etching of the semi-transmissive film. However, the semi-transmissive film pattern was evaluated. The defect thought to be due was not confirmed.

(Reference example)

In Example 2, it carried out similarly to Example 2 except having set the light shielding film into the chromium single layer film.

As a result of the evaluation, the variation of the surface reflectance of the light shielding film was larger than that of Example 2 due to the generation of a small amount of oxygen, and the pattern cross-sectional shape of the light shielding film was also worsened as compared with Examples 1 and 2.

As mentioned above, although this invention was demonstrated based on a preferable Example, this invention is not limited to the said Example.

BRIEF DESCRIPTION OF THE DRAWINGS The figure for demonstrating the manufacturing process which manufactures the gray tone mask of a semi-transmissive film lower arrangement type.

2 is a schematic diagram for explaining a state of generation of bubbles.

3 is a view for explaining a gray tone mask having a translucent film, in which (1) is a partial plan view, and (2) is a partial sectional view.

Fig. 4 is a view for explaining a gray tone mask having a fine light shielding pattern below a resolution limit, where (1) is a partial plan view and (2) is a partial sectional view.

<Description of the symbols for the main parts of the drawings>

1: shading part

2: transmission part

3: gray tone

3a: fine shading pattern

3b: fine permeable part

3a ': translucent film

10: translucent substrate

11: translucent membrane

12: shading film

Claims (5)

On the light-transmissive substrate, the light-shielding film and the semi-transmissive film made of a material containing a metal and silicon and a light-shielding film for shielding exposure light are sequentially formed on the light-shielding film. As a method of manufacturing a photomask in which the semi-transmissive film is patterned to produce a photomask, The semi-transmissive film is patterned by wet etching using an etching solution containing at least one fluorine compound selected from hydrofluoric acid, hydrofluoric acid and ammonium bifluoride, and at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid. , The etching solution is an etching solution in which the molar ratio of the fluorine compound and the oxidant in the etching solution is set to a molar ratio that prevents pattern defects caused by the gas generated with wet etching. On the light-transmissive substrate, the light-shielding film and the semi-transmissive film made of a material containing a metal and silicon and a light-shielding film for shielding exposure light are sequentially formed on the light-shielding film. As a method of manufacturing a photomask in which the semi-transmissive film is patterned to produce a photomask, The patterning of the translucent film is an etching solution containing at least one fluorine compound selected from hydrofluoric acid, hydrofluoric acid and ammonium bifluoride, at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid, and a defoamer or antifoaming agent. It performs by wet etching using the photomask, The manufacturing method of the photomask characterized by the above-mentioned. The method according to claim 1 or 2, The molar ratio of the fluorine compound and the oxidizing agent in the etching liquid is a molar ratio in which the amount of gas generated by wet etching is minimized. The method according to any one of claims 1 to 3, The film thickness of the said translucent film is 10-100 angstroms, The manufacturing method of the photomask characterized by the above-mentioned. The method according to any one of claims 1 to 4, The photomask is a method of manufacturing a photomask, characterized in that the photomask for manufacturing the FPD device.

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