CN112015044A

CN112015044A - Mask blank, halftone mask, manufacturing method, and manufacturing apparatus

Info

Publication number: CN112015044A
Application number: CN202010453412.6A
Authority: CN
Inventors: 诸沢成浩; 汐崎英治
Original assignee: Afac Film Co ltd
Current assignee: Afac Film Co ltd
Priority date: 2019-05-28
Filing date: 2020-05-26
Publication date: 2020-12-01

Abstract

The invention relates to a mask blank, a half-tone mask, a manufacturing method and a manufacturing device. The mask blank of the present invention comprises: a transparent substrate; a halftone layer laminated on a surface of the transparent substrate and containing Cr as a main component; an etch stop layer laminated on the halftone layer; and a light-shielding layer which is laminated on the etching stop layer and mainly contains Cr, wherein the halftone layer comprises: a chemical-resistant layer located at the outermost surface position in the thickness direction, the composition ratio of oxygen being higher than the composition ratio of chromium and the composition ratio of nitrogen; and an optical characteristic layer located at a position adjacent to the transparent substrate in a thickness direction, the composition ratio of oxygen being lower than the composition ratio of chromium and the composition ratio of nitrogen, and ensuring optical characteristics.

Description

Mask blank, halftone mask, manufacturing method, and manufacturing apparatus

Technical Field

The present invention relates to a technique suitable for use in a mask blank, a halftone mask, a manufacturing method, and a manufacturing apparatus.

Background

A substrate used in an FPD (flat panel display) such as a liquid crystal display or an organic EL display is manufactured by using a plurality of masks. In order to reduce the manufacturing process, the number of masks can be reduced by using a semi-transmissive halftone mask.

In addition, in a color filter, an organic EL display, or the like, a spacer (スペーサー) or an opening having an appropriate shape can be formed by exposing and developing a photosensitive organic resin using a semi-transmissive mask and controlling the shape of the organic resin. Therefore, the importance of halftone masks is increasing (patent document 1 and the like).

These halftone masks are formed using a light-shielding layer and a halftone layer (semi-transmissive layer). As the structure of the halftone mask, two structures are known, that is, a structure in which a semi-transmissive layer is formed on an upper portion of a light-shielding layer (an upper structure, an upper type) and a structure in which a semi-transmissive layer is formed on a lower portion of a light-shielding layer (a lower structure, a lower type).

In the case of a halftone mask having an underlying structure, the mask can be completed by forming a laminated film of a halftone layer and a light-shielding layer, and then exposing, developing, and etching each film in a desired pattern. Therefore, the halftone mask of the underlying structure has an advantage that the mask can be formed in a short time.

Cr is generally used as a material of a light shielding layer of the FPD mask, and Cr is preferably used as a material of the halftone layer. Cr exhibits excellent chemical resistance and a processing method as a mask is established.

Further, there is an advantage in that wavelength dependence of transmittance is reduced by forming a halftone layer using Cr.

In the case where Cr is used to form the light-shielding layer and the halftone layer, the Cr etching solution is used to perform etching in order to form a desired pattern. At this time, in order to form a region without the light-shielding layer and the halftone layer, a photoresist layer is laminated on the light-shielding layer or the halftone layer. The photoresist layer is removed after patterning.

In order to remove the resist layer or maintain the surface state, a cleaning process using sulfuric acid, a mixture of sulfuric acid and hydrogen peroxide (water-vapor-sulfuric acid), or ozone is required in the mask manufacturing process to clean the light-shielding layer and/or the halftone layer.

Patent document 1: japanese patent laid-open No. 2006-106575

However, when the halftone layer made of the Cr material is subjected to a condition that the wavelength dependence of the transmittance is small, the halftone layer is etched in a cleaning step using sulfuric acid or ozone used in a mask manufacturing step.

In this case, it is found that a problem occurs in that the transmittance of the halftone layer changes.

In particular, when patterning the light-shielding layer is performed after patterning the halftone layer, there is a problem that the change in transmittance in the halftone layer becomes further large because the etching time becomes long.

In order to solve this problem, the transmittance of the halftone layer obtained by the first film formation may be set to be low in consideration of the transmittance change due to the cleaning, and then the cleaning may be performed using sulfuric acid or ozone.

However, in this case, if the transmittance change in the cleaning step is too large, the variation in the transmittance change in the cleaning step also becomes large. Therefore, it was found that even in this case, it is difficult to control the transmittance, which is an important characteristic of the halftone mask, to a desired value.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and it is desirable to achieve the following object.

1. Chemical resistance with little change in optical characteristics is obtained even in a cleaning step using a mixed solution of sulfuric acid and hydrogen peroxide or ozone.

2. The occurrence of transmittance change in the cleaning step is suppressed.

3. The wavelength dependence of the transmittance is reduced.

4. A halftone mask satisfying the above 1 to 3 can be provided.

5. The wavelength dependence of the transmittance is reduced.

As a result of intensive studies, the present inventors have found that chemical resistance characteristics with little transmittance change can be obtained even in a cleaning step using sulfuric acid or ozone by controlling the composition of oxygen, nitrogen, and chromium in a halftone layer formed using a Cr material.

Further, it was found that in the halftone layer, the chemical resistance can be improved by increasing the oxygen concentration particularly at the surface, but when the oxygen concentration is increased, the wavelength dependence of the transmittance becomes large, and when the oxygen concentration is too high, the chemical resistance is rather lowered.

In contrast, it was found that by appropriately controlling the composition of the halftone layer in the depth direction, the chemical resistance can be improved, and the wavelength dependence of the transmittance of the halftone layer can be reduced.

Further, it was found that the wavelength dependence of the transmittance can be suppressed by controlling the sheet resistance of the halftone layer.

The mask blank according to one embodiment of the present invention includes a transparent substrate; a halftone layer laminated on a surface of the transparent substrate and containing Cr as a main component; an etch stop layer laminated on the halftone layer; and a light-shielding layer which is laminated on the etching stop layer and mainly contains Cr, wherein the halftone layer comprises: a chemical-resistant layer located at the outermost surface position in the thickness direction, the composition ratio of oxygen being higher than the composition ratio of chromium and the composition ratio of nitrogen; and an optical property layer located in the vicinity of the transparent substrate in the thickness direction, the composition ratio of oxygen being lower than the composition ratio of chromium and the composition ratio of nitrogen, and the optical property being secured, whereby the above-mentioned problems are solved.

The mask blank according to one embodiment of the present invention includes a transparent substrate; a light shielding layer which is laminated on the surface of the transparent substrate and mainly contains Cr; and a halftone layer laminated on the light-shielding layer and containing Cr as a main component, the halftone layer having: a chemical-resistant layer located at the outermost surface position in the thickness direction, the composition ratio of oxygen being higher than the composition ratio of chromium and the composition ratio of nitrogen; and an optical property layer located in the vicinity of the transparent substrate in the thickness direction, the composition ratio of oxygen being lower than the composition ratio of chromium and the composition ratio of nitrogen, and the optical property being secured, whereby the above-mentioned problems are solved.

In the mask blank according to one aspect of the present invention, the halftone layer has a composition ratio of oxygen that decreases from a position on the outermost surface in the thickness direction to a position adjacent to the transparent substrate.

In the mask blank according to one aspect of the present invention, in the halftone layer, a composition ratio of oxygen in the chemical-resistant layer is set to be 4 times larger than a minimum composition ratio of oxygen in the optical characteristic layer.

In the mask blank according to one embodiment of the present invention, the sheet resistance of the halftone layer is set to 1.3 × 10³Omega/sq or less.

A method for manufacturing a mask blank according to an aspect of the present invention is a method for manufacturing a mask blank according to any one of the above, including: a film forming step of laminating a base halftone layer containing Cr as a main component; and an oxidation treatment step of oxidizing the base halftone layer formed in the film formation step to form the halftone layer.

In the method for manufacturing a mask blank according to one aspect of the present invention, in the oxidation treatment step, the oxidation treatment of the base halftone layer is performed by an excited oxidation treatment gas.

In the method for manufacturing a mask blank according to one aspect of the present invention, the oxidation treatment gas in the oxidation treatment step is nitrogen oxide.

A method for manufacturing a mask blank according to an aspect of the present invention is a method for manufacturing a mask blank according to any one of the above, including: and a film forming step of laminating the halftone layer containing Cr as a main component.

A method of manufacturing a halftone mask according to an aspect of the present invention is a method of manufacturing a halftone mask using any one of the mask blanks described above, including: patterning the halftone layer through a mask having a predetermined pattern; and a cleaning process of removing the mask.

In the method for manufacturing a halftone mask according to an aspect of the present invention, in the cleaning step, a mixed solution of sulfuric acid and hydrogen peroxide or ozone water is used as the cleaning liquid.

A half-tone mask according to an aspect of the present invention is manufactured by the above-described method for manufacturing a half-tone mask.

A mask blank manufacturing apparatus according to an aspect of the present invention is a manufacturing apparatus used in any one of the above-described mask blank manufacturing methods, and includes: a film forming section for forming the base halftone layer; and an oxidation processing unit that performs oxidation processing on the base halftone layer, wherein the oxidation processing unit includes an excitation gas supply unit that can excite and supply an oxidation processing gas.

A mask blank manufacturing apparatus according to an aspect of the present invention is a manufacturing apparatus used in the above-described mask blank manufacturing method, and includes: and a film forming section for forming the halftone layer, wherein the film forming section includes an excitation gas supply section for supplying an oxidation process gas by exciting the oxidation process gas.

A mask blank according to an aspect of the present invention includes: a transparent substrate; a halftone layer laminated on a surface of the transparent substrate and containing Cr as a main component; an etch stop layer laminated on the halftone layer; and a light-shielding layer which is laminated on the etching stop layer and mainly contains Cr, wherein the halftone layer comprises: a chemical-resistant layer located at the outermost surface position in the thickness direction, the composition ratio of oxygen being higher than the composition ratio of chromium and the composition ratio of nitrogen; and an optical property layer located in the vicinity of the transparent substrate in the thickness direction, the composition ratio of oxygen being lower than the composition ratio of chromium and the composition ratio of nitrogen, and the optical property being secured, whereby the above-mentioned problems are solved.

In the mask blank according to one aspect of the present invention, in the halftone layer, the composition ratio of oxygen may be decreased from the outermost surface position in the thickness direction to a position close to the transparent substrate.

In the mask blank according to one aspect of the present invention, in the halftone layer, a composition ratio of oxygen in the chemical-resistant layer is preferably set to be 4 times larger than a smallest composition ratio of oxygen in the optical characteristic layer.

A method for manufacturing a mask blank according to an aspect of the present invention is any one of the above-described methods for manufacturing a mask blank, and may include: a film forming step of laminating a basic halftone layer containing Cr as a main component on the transparent substrate; and an oxidation treatment step of oxidizing the base halftone layer formed in the film formation step to form the halftone layer.

In the method for manufacturing a mask blank according to an aspect of the present invention, the oxidation treatment of the base halftone layer may be performed by an excited oxidation treatment gas in the oxidation treatment step.

In the method for manufacturing a mask blank according to one aspect of the present invention, the oxidation treatment gas in the oxidation treatment step may be nitrogen oxide.

A method for manufacturing a mask blank according to an aspect of the present invention is any one of the above-described methods for manufacturing a mask blank, and may include: and a film forming step of laminating the halftone layer containing Cr as a main component on the transparent substrate.

In the method for manufacturing a mask blank according to an aspect of the present invention, the method may further include: laminating the etching stopper layer; and a step of laminating the light-shielding layer.

A method for manufacturing a halftone mask according to an aspect of the present invention is a method for manufacturing a halftone mask using a mask blank manufactured by the above-described manufacturing method, and preferably includes: patterning the halftone layer through a mask having a predetermined pattern; and a cleaning process of removing the mask.

In the method for manufacturing a halftone mask according to an aspect of the present invention, in the cleaning step, a mixed solution of sulfuric acid and hydrogen peroxide or ozone water may be used as the cleaning liquid.

The halftone mask according to one embodiment of the present invention can be manufactured by the above-described manufacturing method.

A mask blank manufacturing apparatus according to an aspect of the present invention is a manufacturing apparatus used in any one of the above-described mask blank manufacturing methods, and may include: a film forming section that forms the basic halftone layer on the transparent substrate; and an oxidation processing unit that performs oxidation processing on the base halftone layer, wherein the oxidation processing unit includes an excitation gas supply unit that can excite and supply the oxidation processing gas.

A mask blank manufacturing apparatus according to an aspect of the present invention is a manufacturing apparatus used in the mask blank manufacturing method described above, and may include: and a film forming section for forming the halftone layer on the transparent substrate, wherein the film forming section includes an excitation gas supply section for supplying an oxidation process gas by exciting the oxidation process gas.

A mask blank according to an aspect of the present invention includes: a transparent substrate; a halftone layer laminated on a surface of the transparent substrate, the halftone layer having Cr as a main component, and an etching stopper layer laminated on the halftone layer; and a light-shielding layer which is laminated on the etching stop layer and mainly contains Cr, wherein the halftone layer comprises: a chemical-resistant layer located at the outermost surface position in the thickness direction, the composition ratio of oxygen being higher than the composition ratio of chromium and the composition ratio of nitrogen; and an optical characteristic layer located in a position adjacent to the transparent substrate in a thickness direction, wherein a composition ratio of oxygen is lower than a composition ratio of chromium and a composition ratio of nitrogen, and optical characteristics are ensured.

Thus, the chemical-resistant layer is formed so that the composition ratio of oxygen is higher than the composition ratio of chromium and the composition ratio of nitrogen as the underlying halftone mask, and the chemical resistance in the mask cleaning process can be maintained by the chemical-resistant layer. Therefore, variation in optical characteristics of the halftone layer in the cleaning step can be suppressed, and variation in optical characteristics of the halftone mask manufactured from the mask blank can be suppressed.

Meanwhile, by forming the optical characteristic layer so that the composition ratio of oxygen is lower than the composition ratio of chromium and the composition ratio of nitrogen, the optical characteristic layer can maintain the optical characteristics required for the halftone mask manufactured from the mask blank.

A mask blank according to an aspect of the present invention includes: a transparent substrate; a light-shielding layer which is laminated on a surface of the transparent substrate and mainly contains Cr, and a halftone layer which is laminated on the light-shielding layer and mainly contains Cr, the halftone layer comprising: a chemical-resistant layer located at the outermost surface position in the thickness direction, the composition ratio of oxygen being higher than the composition ratio of chromium and the composition ratio of nitrogen; and an optical characteristic layer located in a position adjacent to the transparent substrate in a thickness direction, wherein a composition ratio of oxygen is lower than a composition ratio of chromium and a composition ratio of nitrogen, and optical characteristics are ensured.

Thus, the chemical-resistant layer is formed so that the composition ratio of oxygen is higher than the composition ratio of chromium and the composition ratio of nitrogen as the halftone mask placed thereon, and the chemical resistance in the mask cleaning step can be maintained by the chemical-resistant layer. Therefore, variation in optical characteristics of the halftone layer in the cleaning step can be suppressed, and variation in optical characteristics of the halftone mask manufactured from the mask blank can be suppressed.

Meanwhile, the optical characteristic layer is formed so that the composition ratio of oxygen is lower than the composition ratio of chromium and the composition ratio of nitrogen, so that the optical characteristics required for the halftone mask manufactured from the mask blank can be maintained by the halftone layer through the optical characteristic layer.

In the mask blank according to one aspect of the present invention, in the halftone layer, a composition ratio of oxygen decreases from a position on an outermost surface in a thickness direction to a position adjacent to the transparent substrate.

This makes it possible to provide a mask blank having a halftone layer capable of simultaneously maintaining chemical resistance and suppressing variation in optical characteristics in a cleaning process.

This makes it possible to provide a mask blank having a halftone layer capable of simultaneously maintaining sufficient chemical resistance on the surface of the halftone layer exposed to a cleaning liquid and suppressing variation in optical characteristics as the halftone layer after a cleaning step involving pattern formation.

Thus, by setting the sheet resistance, the difference in transmittance due to the wavelength of the exposure light in the halftone layer can be reduced. Thus, it is possible to provide a halftone mask that suppresses the occurrence of a difference in transmittance due to the wavelength of exposure light and that can easily cope with exposure light of a complex wavelength.

A method for manufacturing a mask blank according to an aspect of the present invention is a method for manufacturing a mask blank according to any one of the above-described methods, including: a film forming step of laminating a base halftone layer containing Cr as a main component; and an oxidation treatment step of oxidizing the base halftone layer formed in the film formation step to form the halftone layer.

Thus, the base halftone layer having desired optical characteristics can be easily formed by the film formation step using conventionally known film formation conditions for films containing Cr as a main component. Then, the base halftone layer is oxidized by the oxidation treatment step, thereby forming a halftone layer having a chemical-resistant layer and an optical characteristic layer, wherein the chemical-resistant layer is located at the outermost surface position in the thickness direction, the composition ratio of oxygen is higher than the composition ratio of chromium and the composition ratio of nitrogen, the optical characteristic layer is located at a position close to the transparent substrate in the thickness direction, and the composition ratio of oxygen is lower than the composition ratio of chromium and the composition ratio of nitrogen, and the optical characteristic layer is ensured.

In this case, a chemical-resistant layer having sufficient chemical resistance can be formed, and a halftone layer maintaining optical characteristics required as a halftone mask can be formed.

Specifically, when the chemical-resistant layer having a higher oxygen composition ratio than the chromium composition ratio and the nitrogen composition ratio is formed at the outermost surface position in the thickness direction, the optical characteristic layer having the oxygen composition ratio substantially equal to that of the base halftone layer and ensuring the optical characteristics can be formed at a position adjacent to the transparent substrate in the thickness direction.

Further, a halftone mask in which such a halftone layer is laminated on an upper portion of the light-shielding layer can be provided. Alternatively, a halftone mask in which an etching stopper layer and a light shielding layer are sequentially laminated on the halftone layer may be provided.

A method for manufacturing a mask blank according to an aspect of the present invention is a method for manufacturing a mask blank according to any one of the above-described methods, including: a film forming step of laminating a base halftone layer containing Cr as a main component on the transparent substrate; and an oxidation treatment step of oxidizing the base halftone layer formed in the film formation step to form the halftone layer.

Thus, the base halftone layer having desired optical characteristics can be easily formed on the transparent substrate by the film formation step using the film formation conditions for the film mainly composed of Cr, which have been known in the related art. Then, the base halftone layer is oxidized by the oxidation treatment step, thereby forming a halftone layer having a chemical-resistant layer and an optical characteristic layer, wherein the chemical-resistant layer is located at the outermost surface position in the thickness direction, the composition ratio of oxygen is higher than the composition ratio of chromium and the composition ratio of nitrogen, the optical characteristic layer is located at a position close to the transparent substrate in the thickness direction, and the composition ratio of oxygen is lower than the composition ratio of chromium and the composition ratio of nitrogen, and the optical characteristic layer is ensured.

Specifically, when the chemical-resistant layer having a higher oxygen composition ratio than the chromium composition ratio and the nitrogen composition ratio is formed at the outermost surface position in the thickness direction, the optical characteristic layer having the oxygen composition ratio approximately equal to that of the base halftone layer and ensuring the optical characteristics can be formed at a position close to the transparent substrate in the thickness direction.

In the method for manufacturing a mask blank according to an aspect of the present invention, in the oxidation treatment step, the oxidation treatment of the base halftone layer is performed by an excited oxidation treatment gas.

Thus, when the chemical-resistant layer is formed, the composition ratio of oxygen can be maintained at a position close to the transparent substrate in the thickness direction of the base halftone layer to be approximately equal to that of the base halftone layer. Therefore, an optical characteristic layer that ensures optical characteristics can be formed.

In this case, the oxidation state of the base halftone layer can be controlled to form a chemical-resistant layer having sufficient chemical resistance, and the oxygen composition ratio can be controlled to be about the same as that of the base halftone layer at a position close to the transparent substrate in the thickness direction of the base halftone layer.

Further, the mask blank can be produced by simply controlling the atmosphere gas in the oxidation treatment step.

A method for manufacturing a mask blank according to an aspect of the present invention is a method for manufacturing a mask blank according to any one of the above-described methods, including: and a film forming step of laminating the halftone layer containing Cr as a main component.

Thus, in the step of forming the halftone layer, the composition ratio of oxygen can be changed in the thickness direction, and the halftone layer having the chemical-resistant layer and the optical characteristic layer can be formed.

In this case, the mask blank can be produced by controlling only the atmosphere in the film formation step.

A method for manufacturing a mask blank according to an aspect of the present invention is any one of the above-described methods for manufacturing a mask blank, including: and a film forming step of laminating the halftone layer containing Cr as a main component on the transparent substrate.

A method for manufacturing a mask blank according to an aspect of the present invention includes: laminating the etching stopper layer; and a step of laminating the light-shielding layer. Thus, a halftone mask having sufficient chemical resistance and desired optical characteristics can be manufactured.

Here, as an etching stopper layer having sufficient selectivity, a halftone mask having a desired pattern shape can be manufactured while exhibiting etching stopper capability.

A method for manufacturing a halftone mask according to an aspect of the present invention is a method for manufacturing a halftone mask using a mask blank manufactured by the above-described manufacturing method, including: patterning the halftone layer through a mask having a predetermined pattern; and a cleaning process of removing the mask.

Thus, a halftone mask having a desired pattern and a desired optical characteristic layer can be manufactured from a mask blank having a halftone layer having: an optical property layer capable of simultaneously maintaining sufficient chemical resistance on the surface of the halftone layer exposed to a cleaning liquid and suppressing variation in optical properties as the halftone layer after a cleaning step involving pattern formation.

In the cleaning step, the chemical-resistant layer can maintain a state in which the variation in optical characteristics is suppressed, and the cleaning required in the cleaning step can be performed to remove foreign matter and a photomask on the surface of the halftone layer.

A halftone mask according to an embodiment of the present invention is manufactured by the above manufacturing method.

This makes it possible to use the halftone mask having desired optical characteristics.

A mask blank manufacturing apparatus according to an aspect of the present invention is a manufacturing apparatus used in any one of the above-described mask blank manufacturing methods, and includes: a film forming section for forming the base halftone layer; and an oxidation processing unit that performs oxidation processing on the base halftone layer, wherein the oxidation processing unit includes an excitation gas supply unit that can excite and supply the oxidation processing gas.

Thus, a mask blank having an optical characteristic layer which is formed in the chemical-resistant layer at a position close to the transparent substrate in the thickness direction of the base halftone layer, maintains the composition ratio of oxygen at a level equivalent to that of the base halftone layer, and ensures optical characteristics can be manufactured.

A mask blank manufacturing apparatus according to an aspect of the present invention is a manufacturing apparatus used in any one of the above-described mask blank manufacturing methods, and includes: a film forming section for forming the base halftone layer on the transparent substrate; and an oxidation processing unit that performs oxidation processing on the base halftone layer, wherein the oxidation processing unit includes an excitation gas supply unit that can excite and supply the oxidation processing gas.

A mask blank manufacturing apparatus according to an aspect of the present invention is a manufacturing apparatus used in the above-described mask blank manufacturing method, including: and a film forming section for forming the halftone layer on the transparent substrate, wherein the film forming section includes an excitation gas supply section for supplying an oxidation process gas by exciting the oxidation process gas.

According to one embodiment of the present invention, it is possible to provide a halftone mask having chemical resistance characteristics with little change in optical characteristics even in a cleaning process using a mixture of sulfuric acid and hydrogen peroxide or ozone, and capable of suppressing the occurrence of transmittance change in the cleaning process and reducing the wavelength dependence of transmittance.

Drawings

Fig. 1 is a sectional view showing a mask blank according to a first embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a halftone mask according to a first embodiment of the present invention.

Fig. 3 is a schematic view showing a film deposition apparatus in the method for manufacturing a mask blank according to the first embodiment of the present invention.

Fig. 4 is a schematic view showing a film deposition apparatus in the method for manufacturing a mask blank according to the first embodiment of the present invention.

Fig. 5 is a flowchart showing a method of manufacturing a mask blank and a halftone mask according to a first embodiment of the present invention.

Fig. 6 is a process diagram illustrating a method for manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 7 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 8 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 9 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 10 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 11 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 12 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 13 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 14 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 15 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 16 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 17 is a process diagram illustrating a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 18 is a process diagram showing a method of manufacturing a halftone mask according to the first embodiment of the present invention.

Fig. 19 is a diagram showing an embodiment of the present invention.

FIG. 20 is a diagram showing an embodiment of the present invention.

FIG. 21 is a diagram showing an embodiment of the present invention.

Fig. 22 is a diagram showing an embodiment of the present invention.

FIG. 23 is a diagram showing an embodiment of the present invention.

FIG. 24 is a diagram showing an embodiment of the present invention.

FIG. 25 is a diagram showing an embodiment of the present invention.

Fig. 26 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 27 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 28 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 29 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 30 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 31 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 32 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 33 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 34 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 35 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 36 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 37 is a process diagram showing a method of manufacturing a halftone mask according to a second embodiment of the present invention.

Fig. 38 is a flowchart showing a method of manufacturing a mask blank and a halftone mask according to a second embodiment of the present invention.

FIG. 39 is a diagram showing an embodiment of the present invention.

Description of the reference numerals

MB … mask blank

M … half-tone mask

M1 … transmissive region

M2 … halftone area

M3 … light blocking area

S … glass substrate (transparent substrate)

PR1, PR2 … photoresist layer

PR1p, PR2p … Photoresist Pattern

11 … halftone layer

11a … chemical resistant layer

11b … optical Property layer

11A … base halftone layer

11p … halftone pattern

12 … etch stop layer

12p0 … etch stop layer transmission pattern

12p … etch stop pattern

13 … light-shielding layer

13p0 … light-shielding layer transmissive pattern

13p … light blocking Pattern

Detailed Description

A mask blank, a half-tone mask, a manufacturing method, and a manufacturing apparatus according to a first embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 is a schematic cross-sectional view showing a mask blank according to the present embodiment, and reference numeral MB in fig. 1 denotes a mask blank.

The mask blank MB according to the present embodiment is provided to a halftone mask used in a range where the wavelength of exposure light is 365nm to 436nm, for example.

As shown in fig. 1, the mask blank MB is composed of a transparent substrate S, a halftone layer 11 formed on the transparent substrate S, an etching stopper layer 12 formed on the halftone layer 11, and a light-shielding layer 13 formed on the etching stopper layer 12.

As the transparent substrate S, a material having excellent transparency and optical isotropy can be used, and for example, a quartz glass substrate can be used. The size of the transparent substrate S is not particularly limited, and may be appropriately selected depending on a substrate to be exposed using the mask (for example, a substrate for an FPD such as an LCD (liquid crystal display), a plasma display, and an organic EL (electroluminescence) display, or a semiconductor substrate). In the present embodiment, a substrate having a diameter of about 100mm or a rectangular substrate having a side of about 50 to 100mm and a side of 300mm or more can be used, and a quartz substrate having a length of 450mm, a width of 550mm and a thickness of 8mm or a substrate having a maximum side of 1000mm or more and a thickness of 10mm or more can be used.

In addition, the flatness of the transparent substrate S may also be reduced by polishing the surface of the transparent substrate S. The flatness of the transparent substrate S may be, for example, 20 μm or less. This makes it possible to provide a mask having a large depth of focus and contributing to fine and highly accurate pattern formation. Further, the flatness is preferably a small value of 10 μm or less.

The halftone layer 11 is a layer containing Cr as a main component, and specifically may be made of one material selected from the group consisting of simple Cr and Cr oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides. And the halftone layer 11 may also be constituted by laminating two or more materials selected from these materials.

For example, the halftone layer 11 has a chemical-resistant layer 11a having a composition ratio of oxygen higher than a composition ratio of chromium and a composition ratio of nitrogen at a position that is the outermost surface in the thickness direction. The halftone layer 11 has an optical characteristic layer 11b having a composition ratio of oxygen lower than that of chromium and that of nitrogen at a position adjacent to the transparent substrate S in the thickness direction.

In the halftone layer 11, the optical characteristic layer 11b has a characteristic sufficient for use as a halftone mask.

In the halftone layer 11, the composition ratio of oxygen decreases continuously from the outermost surface position close to the etching stopper layer 12 toward the position close to the transparent substrate S in the thickness direction. The gradient of the oxygen concentration in the halftone layer 11 is set to be substantially constant in the thickness direction.

The gradient of the oxygen concentration in the halftone layer 11 gradually decreases from the outermost surface position with respect to the thickness direction.

Therefore, a clear boundary surface is not formed between the chemical-resistant layer 11a and the optical characteristic layer 11 b.

In addition, the composition ratio of oxygen may be disturbed in the vicinity of the outermost surface of the halftone layer 11 and in the vicinity of the position adjacent to the transparent substrate S. However, the content of the organic compound is about several atm%, and the chemical resistance and optical properties of the halftone layer 11 are not problematic.

The halftone layer 11 has a composition ratio of nitrogen that continuously increases from a position on the outermost surface of the etching stopper layer 12 toward a position on the transparent substrate S in the thickness direction. The gradient of the nitrogen concentration in the halftone layer 11 is set to be substantially constant in the thickness direction.

The halftone layer 11 has a substantially constant composition ratio of carbon in the thickness direction from the outermost surface of the etching stopper layer 12 to the transparent substrate S. The halftone layer 11 continuously and slightly increases in thickness direction from the outermost surface position adjacent to the etching stopper layer 12 to the position adjacent to the transparent substrate S.

In the halftone layer 11, the composition ratio of the largest oxygen in the chemical-resistant layer 11a is set to be 4 times larger than the composition ratio of the smallest oxygen in the optical characteristic layer 11 b.

In the halftone layer 11, the composition ratio of the largest oxygen in the chemical-resistant layer 11a is set to be 5 times larger than the composition ratio of the smallest oxygen in the optical characteristic layer 11 b.

In the halftone layer 11, the maximum composition ratio of oxygen in the chemical-resistant layer 11a is set to be slightly smaller than 6 times the minimum composition ratio of oxygen in the optical characteristic layer 11 b.

As shown in fig. 20 described later, the chemical-resistant layer 11a may be a region in which the composition ratio of oxygen is higher than the composition ratio of carbon or the composition ratio of nitrogen in the thickness direction of the halftone layer 11.

In the chemical-resistant layer 11a, the composition ratio of oxygen decreases from the outermost surface position close to the etching stopper layer 12 toward the transparent substrate S in the thickness direction.

As an example, as shown in fig. 20 described later, the composition ratio of oxygen is set to be greater than 60 atm% at the outermost surface positions of the halftone layer 11 and the chemical-resistant layer 11 a. Further, the composition ratio of oxygen is set to be greater than 65 atm% at the outermost surface positions of the halftone layer 11 and the chemical-resistant layer 11 a.

The composition ratio of chromium is set to be greater than 20 atm% and less than 30 atm% at the outermost surface positions of the halftone layer 11 and the chemical-resistant layer 11 a. Further, the composition ratio of nitrogen is set to be less than 10 atm% at the outermost surface positions of the halftone layer 11 and the chemical-resistant layer 11 a.

In addition, the composition ratio of the smallest oxygen in the optical characteristic layer 11b is set to be less than 15 atm%. The composition ratio of the minimum oxygen in the optical characteristic layer 11b is set to about 10 atm%. It is not preferable if the composition ratio of the smallest oxygen in the optical characteristic layer 11b is more than 20 atm%.

As shown in fig. 20 described later, the optical characteristic layer 11b may be a region in which the composition ratio of oxygen is lower than the composition ratio of carbon or the composition ratio of nitrogen in the thickness direction of the halftone layer 11.

In the optical characteristic layer 11b, the composition ratio of oxygen decreases from the position close to the chemical-resistant layer 11a of the etching stopper layer 12 to the position close to the transparent substrate S in the thickness direction.

The position where the composition ratio of oxygen in the optical characteristic layer 11b is the smallest is set at a position close to the transparent substrate S.

The etching stopper layer 12 may be a metal silicide film containing nitrogen, for example, a film containing at least one metal selected from Ni, Co, Fe, Ti, Al, Nb, Mo, W, and Hf, or an alloy of the above metals and Si, particularly a molybdenum silicide film or MoSi_X(X.gtoreq.2) film (e.g., MoSi₂Film, MoSi₃Film or MoSi₄Films, etc.).

For example, regarding the composition of the MoSi film, in the composition ratio of Mo to Si, MoSi_XThe value of X in the film may be in the range of 2.0 to 3.7. Here, if a smaller value is selected as MoSi within the range_XThe value of X in the film can increase the etching rate. In addition, if a larger value is selected as MoSi within the range_XThe value of X in the film can reduce the etching rate.

The etching stopper layer 12 is provided with a high-nitrogen region having a nitrogen concentration of 30 atm% or more in a position adjacent to the light shielding layer 13 in the thickness direction.

The thickness of the high-nitrogen region of the etching stopper layer 12 and the low-nitrogen region closer to the halftone layer 11 than the high-nitrogen region are set to 15nm to 40 nm.

By setting the nitrogen concentration and the composition ratio of Mo and Si, which is the composition of the MoSi film, as the etching stopper layer 12, the film characteristics of the etching stopper layer 12 with respect to etching, that is, the etching rate can be set.

Thus, the film composition can be set in the following manner: that is, in the etching of the light shielding layer 13 located above (on the front surface side, outside) the etching stopper layer 12, the etching stopper layer 12 has high selectivity, the etching rate of the etching stopper layer 12 is reduced, and the etching stopper layer 12 has etching resistance and prevents the halftone layer 11 from being damaged.

The light-shielding layer 13 contains Cr as a main component, specifically, Cr and nitrogen. In this case, the light-shielding layer 13 may be formed by laminating one material or two or more materials selected from the group consisting of simple Cr and Cr oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides.

The light-shielding layer 13 is formed to have a thickness (for example, 80nm to 200nm) capable of obtaining predetermined optical characteristics.

Here, both the light-shielding layer 13 and the halftone layer 11 are chromium-based thin films and are oxidized and nitrided, and the halftone layer 11 is set to be less susceptible to oxidation than the light-shielding layer 13 because the degree of oxidation of the halftone layer 11 is greater.

The mask blank MB according to the present embodiment can be applied to, for example, manufacturing a halftone mask M as a patterning mask for a glass substrate for an FPD.

Fig. 2 is a cross-sectional view showing a halftone mask manufactured from the mask blank of the present embodiment.

As shown in fig. 2, the half-tone mask M according to the present embodiment includes a mask blank MB, a transmissive region M1, a half-tone region M2, and a light-shielding region M3.

The transmissive area M1 is an area where the glass substrate (transparent substrate) S is exposed.

The halftone area M2 is only an area where a halftone pattern 11p patterned by the halftone layer 11 in the mask blank MB is formed on the glass substrate (transparent substrate) S.

The light-shielding region M3 is a region in which the halftone pattern 11p, the etching stopper pattern 12p, and the light-shielding pattern 13p, which are patterned by the halftone layer 11, the etching stopper layer 12, and the light-shielding layer 13 in the mask blank MB, are laminated.

In the halftone mask M, the halftone area M2 is an area that can make transmitted light semi-transmissive, for example, during exposure processing. The light-shielding region M3 is a region in which irradiation light can not be transmitted by the light-shielding pattern 13p in the exposure process.

For example, according to the halftone mask M, in the exposure process, light in the wavelength region, particularly, a composite wavelength including g-line (436nm), h-line (405nm), and i-line (365nm) can be used as the exposure light. Thus, the shape of the organic resin can be controlled by exposure and development, and a spacer or an opening having an appropriate shape can be formed. In addition, the pattern accuracy can be greatly improved, and a fine and highly accurate pattern can be formed.

According to this halftone mask, it is possible to improve the pattern accuracy by using the light in the wavelength region, and to form a fine and highly accurate pattern. This enables the production of a high-quality flat panel display or the like.

Next, a method for manufacturing the mask blank MB according to the present embodiment will be described.

The mask blank MB in this embodiment is manufactured by the manufacturing apparatus shown in fig. 3 or 4.

Fig. 3 is a schematic view showing a manufacturing apparatus for manufacturing a mask blank according to the present embodiment.

The manufacturing apparatus S10 shown in fig. 3 is a reciprocating sputtering apparatus and an apparatus for performing oxidation treatment. The manufacturing apparatus S10 includes a loading and unloading chamber S11, a film forming chamber (vacuum processing chamber, film forming section) S12, and an oxidation processing chamber (oxidation processing section) S13 for performing oxidation processing.

A conveyance device (conveyance unit) S11a and an exhaust device (exhaust unit) S11b are provided in the loading and unloading chamber S11.

The conveying device S11a conveys the glass substrate S carried in from the outside to the film forming chamber S12. The exhaust device S11b is a rotary pump or the like for roughly evacuating the inside of the loading and unloading chamber S11.

The loading and unloading chamber S11 is connected to the film forming chamber S12 through a sealing device (sealing unit) S17.

In the film forming chamber S12, a substrate holding device (substrate holding unit) S12a, a cathode electrode (backing plate) S12c having a target S12b, a power source S12d, a gas introduction device (gas introduction unit) S12e, and a high vacuum exhaust device S12f are provided.

The substrate holding device S12a receives the glass substrate S conveyed by the conveying device S11a and holds the glass substrate S so as to face the target S12b during film formation.

The substrate holding device S12a can also carry in the glass substrate S from the loading and unloading chamber S11. The substrate holding device S12a can also carry the glass substrate S out to the loading and unloading chamber S11.

The target S12b is made of a material having a composition required for forming a base halftone layer 11A described later on the glass substrate S.

The power source S12d applies a sputtering voltage of a negative potential to the cathode electrode (backing plate) S12c having the target S12 b.

The gas introduction device S12e introduces a gas into the film forming chamber S12.

The high-vacuum evacuation device S12f is a turbo molecular pump or the like for evacuating the inside of the film forming chamber S12.

These cathode electrode (back plate) S12c, power source S12d, gas introduction device S12e, and high vacuum exhaust device S12f have at least a structure for supplying a material for forming halftone layer 11.

The film forming chamber S12 is connected to the oxidation treatment chamber S13 via a sealing device S18.

In the oxidation processing chamber S13, a substrate holding device S13a, a gas introduction device S13e, a gas exciting device (gas exciting unit) S13r, and a high vacuum exhaust device S13f are provided.

The substrate holding device S13a receives the glass substrate S conveyed by the substrate holding device S12a, and holds the glass substrate S to be opposed to the gas exciting device S13r in the oxidation process.

The substrate holding device S13a can also carry in the glass substrate S from the film forming chamber S12. The substrate holding device S13a can also carry the glass substrate S out of the film forming chamber S12.

The gas introduction device S13e introduces a gas into the oxidation chamber S13.

The high vacuum exhaust apparatus S13f is a turbo molecular pump or the like for evacuating the inside of the oxidation processing chamber S13.

The gas exciting device S13r excites the gas supplied from the gas introducing device S13e into the oxidation processing chamber S13 as an excited oxidation gas.

Here, the excited oxidizing gas refers to a state of plasma, radicals, ions, or the like.

The gas exciting device S13r can eject the excited oxidizing gas toward the glass substrate S held by the substrate holding device S13 a.

These gas exciting device S13r, gas introducing device S13e, and high vacuum exhaust device S13f have a structure for performing oxidation treatment on the base halftone layer 11A.

The gas exciting device S13r and the gas introducing device S13e are excited gas supply units.

In the manufacturing apparatus S10 shown in fig. 3, the base halftone layer 11A is formed by sputtering film formation in the film forming chamber (vacuum processing chamber) S12 on the glass substrate S carried in from the loading and unloading chamber S11. Then, the oxidation treatment is performed on the base halftone layer 11A in the oxidation treatment chamber S13 to form the halftone layer 11. Then, the glass substrate S after the processing is carried out from the loading and unloading chamber S11.

At the time of film formation, a sputtering gas and a reaction gas are supplied from the gas introduction device S12e to the film formation chamber S12, and a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S12 c. Further, a predetermined magnetic field may be formed in the target S12b by a magnetron magnetic circuit. In the film forming chamber S12, ions of the sputtering gas excited by the plasma collide with the target S12b of the cathode electrode S12c, thereby flying particles of the film forming material. The ejected particles are bonded to the reaction gas and then adhere to the glass substrate S, thereby forming a predetermined film on the surface of the glass substrate S.

Fig. 4 is a schematic view showing a manufacturing apparatus for manufacturing a mask blank according to the present embodiment.

The manufacturing apparatus S20 shown in fig. 4 is an in-line sputtering apparatus and an apparatus for performing oxidation treatment. The manufacturing apparatus S20 includes a loading chamber S21, a film forming chamber (vacuum processing chamber, film forming section) S22, an oxidation processing chamber (oxidation processing section) S23, and an unloading chamber S25.

The loading chamber S21 is provided with a transport device S21a and an exhaust device S21 b.

The conveying device S21a conveys the glass substrate S carried in from the outside to the film forming chamber S22. The exhaust device S21b is a rotary pump or the like for roughly evacuating the inside of the loading chamber S21.

The loading chamber S21 is connected to a film forming chamber (vacuum processing chamber) S22 via a sealing device S27.

The film forming chamber S22 is provided with a substrate holding device S22a, a cathode electrode (backing plate) S22c having a target S22b, a power source S22d, a gas introducing device S22e, and a high vacuum exhaust device S22 f.

The substrate holding device S22a receives the glass substrate S conveyed by the conveying section S21a and holds the glass substrate S so as to face the target S22b during film formation.

The substrate holding device S22a can also carry in the glass substrate S from the loading chamber S21. The substrate holding device S22a can also carry out the glass substrate S to the oxidation processing chamber (oxidation processing section) S23.

The target S22b is made of a material having a composition required for forming a base halftone layer 11A described later on the glass substrate S.

The cathode electrode (back plate) S22c, the power source S22d, the gas introduction device S22e, and the high vacuum exhaust device S22f have a structure for supplying a material for forming the halftone layer 11 and the like.

The power source S22d applies a sputtering voltage of a negative potential to the cathode electrode (backing plate) S22c having the target S22 b.

The gas introduction device S22e introduces a gas into the film forming chamber S22.

The high-vacuum evacuation device S22f is a turbo molecular pump or the like for evacuating the inside of the film forming chamber S22.

The film forming chamber S22 is connected to an oxidation treatment chamber (oxidation treatment section) S23 via a sealing device S28.

In the oxidation processing chamber S23, a substrate holding device S23a, a gas introduction device S23e, a gas excitation device S23r, and a high vacuum exhaust device S23f are provided.

The substrate holding device S23a receives the glass substrate S conveyed by the substrate holding device S22a, and holds the glass substrate S so as to face the gas exciting device S23r in the oxidation process.

The substrate holding device S23a can also carry in the glass substrate S from the film forming chamber S22. The substrate holding device S23a can also hold the glass substrate S.

The gas introduction device S23e introduces a gas into the oxidation chamber S23.

The high vacuum exhaust apparatus S23f is a turbo molecular pump or the like for evacuating the inside of the oxidation processing chamber S13.

The gas exciting apparatus S23r excites the gas supplied from the gas introducing apparatus S23e into the oxidation processing chamber S23 as an excited oxidation gas.

The gas exciting device S23r can eject the excited oxidizing gas toward the glass substrate S held by the substrate holding device S23 a.

The gas exciting device S23r and the gas introducing device S23e are excited gas supply units.

The gas exciting device S23r, the gas introducing device S23e, and the high vacuum exhaust device S23f are configured to oxidize at least the base halftone layer 11A.

The oxidation processing chamber (oxidation processing unit) S23 is connected to the unloading chamber S25 via a sealing device S28.

The unloading chamber S25 is provided with a transfer device S25a for transferring the glass substrate S carried in from the oxidation processing chamber (oxidation processing unit) S23 to the outside, and an exhaust device S25b such as a rotary pump for rough evacuation of the inside of the chamber.

In the manufacturing apparatus S20 shown in fig. 4, the base halftone layer 11A is first formed by sputtering film formation in the film forming chamber (vacuum processing chamber) S22 with respect to the glass substrate S carried in from the loading chamber S21. Then, the oxidation treatment is performed on the base halftone layer 11A in the oxidation treatment chamber S23. Then, the glass substrate S on which the film formation is completed is carried out from the unloading chamber S25.

Fig. 5 is a flowchart showing a manufacturing process of a mask blank or a halftone mask in the present embodiment. Fig. 6 to 10 are sectional views showing a process of manufacturing a mask blank according to the present embodiment.

As shown in fig. 5, the method of manufacturing the mask blank MB according to the present embodiment includes a substrate preparation step S00, a base halftone layer forming step S01a, an oxidation treatment step S01b, an etching stop layer forming step S02, and a light shielding layer forming step S03.

Here, in the description of the method for manufacturing the mask blank MB in the present embodiment, the process performed by the manufacturing apparatus S20 shown in fig. 4 will be described. When the mask blank MB is manufactured by the manufacturing apparatus S10 shown in fig. 3, the reference numeral of the number S20 is replaced with the number S10 for reading, and the unloading chamber S25 is replaced with the loading and unloading chamber S11 for reading, and the like.

In the substrate preparation step S00 shown in fig. 5, a glass substrate S (fig. 6) subjected to the surface treatment and the like described above is prepared. Then, the transparent substrate S is carried into the loading chamber S21 shown in fig. 4.

In the loading chamber S21, the transparent substrate S is supported by the carrying device S21a, and after the loading chamber S21 is sealed, the inside of the loading chamber S21 is roughly evacuated by the evacuation device S21 b.

In this state, the sealing device S27 is released, the transparent substrate S is conveyed by the conveying device S21a, the conveyed glass substrate S is received by the substrate holding device S22a, and the transparent substrate S is conveyed into the film forming chamber (vacuum processing chamber) S22.

In the film forming chamber S22, the sealing device S27 is sealed.

In the film forming chamber (vacuum processing chamber) S22, the transparent substrate S is held by the substrate holding device S22 a.

In the base halftone layer forming step S01a shown in fig. 5, the inside of the film forming chamber S22 is evacuated in advance by the high vacuum evacuation device S22f in the film forming chamber (vacuum processing chamber) S22 shown in fig. 4. Then, a sputtering gas and a reaction gas are supplied from the gas introduction device S22e to the film forming chamber S22, and a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S22 c. Further, a predetermined magnetic field may be formed in the target S22b by a magnetron magnetic circuit.

In the film forming chamber S22, ions of the sputtering gas excited by the plasma collide with the target S22b of the cathode electrode S22c, thereby flying particles of the film forming material. The flying particles are bonded to the reaction gas and then adhere to the glass substrate S, thereby forming a base halftone layer 11A on the surface of the glass substrate S (fig. 7).

Here, the target S22b having a composition necessary for forming the base halftone layer 11A is replaced in advance. The composition of the film-forming gas necessary for forming the base halftone layer 11A is switched so that the partial pressure is controlled while supplying nitrogen gas or the like in different amounts from the gas introduction device S22e, and is within a predetermined range.

In this case, as shown in fig. 19 to be described later, the formed base halftone layer 11A can have a predetermined composition ratio of oxygen, carbon, nitrogen, and chromium, respectively, in the thickness direction.

In the oxidation process S01b shown in fig. 5, the sealing device S28 is released from the film forming chamber S22 shown in fig. 4, the transparent substrate S is transported by the substrate holding device S22a, the transported glass substrate S is received by the substrate holding device S23a, and the transparent substrate S is transported into the oxidation process chamber S23.

A base halftone layer 11A is formed on the transparent substrate S.

In the oxidation processing chamber S23, the sealing device S28 is sealed.

In the oxidation processing chamber S23, the transparent substrate S is held by the substrate holding device S23 a.

In the oxidation processing chamber S23, the inside of the oxidation processing chamber S23 is evacuated in advance by the high vacuum evacuation device S23 f. Then, the oxidation processing gas is supplied from the gas introduction device S23e to the oxidation processing chamber S23.

At the same time, the gas supplied from the gas introduction device S23e into the oxidation processing chamber S23 is excited by the gas exciting device S23r to be used as an excited oxidation gas of plasma, radicals, ions, or the like.

The gas exciting device S23r ejects an excited oxidizing gas to the surface of the base halftone layer 11A of the glass substrate S.

As shown in fig. 20 described later, the base halftone layer 11A sprayed with the excited oxidation gas is oxidized and becomes a halftone layer 11 having predetermined oxygen composition ratio, carbon composition ratio, nitrogen composition ratio, and chromium composition ratio in the thickness direction (fig. 8).

In the halftone layer 11, a chemical-resistant layer 11a is formed at a position that is the outermost surface in the thickness direction. In addition, in the halftone layer 11, an optical characteristic layer 11b is formed at a position close to the transparent substrate S in the thickness direction.

As described above, the chemical-resistant layer 11a is formed such that the composition ratio of oxygen is higher than the composition ratio of chromium and the composition ratio of nitrogen.

In addition, as described above, the optical characteristic layer 11b is formed so that the composition ratio of oxygen is lower than the composition ratio of chromium and the composition ratio of nitrogen.

At this time, as the oxidation treatment gas, oxygen gas, carbon dioxide gas, and N as a nitrogen oxidizing gas may be applied as long as the base halftone layer 11A containing chromium or the like can be oxidized₂O, NO, etc.

Here, in order to form the halftone layer 11 having the chemical-resistant layer 11a and the optical characteristic layer 11b, it is necessary to accurately control the oxidation state. Therefore, the oxidizing ability in the oxidizing treatment gas is preferably not excessively strong.

For example, the oxidizing ability of the oxidizing gas in the oxidizing step S01b is expressed as O₂＞H₂O＞CO₂＞CO＞N₂The order of O > NO becomes smaller, so in order to precisely control the oxidation state of chromium, NO gas is preferably used.

Here, CO having a stronger oxidizing power than NO gas is used₂The composition of the gas is shown in fig. 21 described later.

The condition of the oxidation treatment gas may be controlled by the flow rate of the gas introduced into the apparatus for performing the oxidation treatment, for example, by the flow rate of the oxidation treatment gas. Further, the treatment may be diluted with a gas such as nitrogen or argon.

In addition, when plasma discharge is used as the excitation condition of the oxidation treatment gas, the excited state can be controlled by the discharge pressure or the discharge power. In the sputtering apparatus, the oxidation process may be performed by reducing the discharge power to reduce the film formation rate.

In the etching stopper layer forming step S02 shown in fig. 5, the sealing device S28 shown in fig. 4 is released, the transparent substrate S is transported from the oxidation processing chamber S23 by the substrate holding device S23a, the glass substrate S transported by the substrate holding device S22a is received, and the transparent substrate S is transported into the film forming chamber S22.

In the film forming chamber (vacuum processing chamber) S22, the inside of the film forming chamber S22 is evacuated by the high vacuum evacuation device S22 f. Then, a sputtering gas and a reaction gas are supplied from the gas introduction device S22e to the film forming chamber S22, and a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S22 c. Further, a predetermined magnetic field may be formed in the target S22b by a magnetron magnetic circuit.

In the film forming chamber S22, ions of the sputtering gas excited by the plasma collide with the target S22b of the cathode electrode S22c, thereby flying particles of the film forming material. The flying particles are bonded to the reaction gas and then adhere to the glass substrate S, thereby forming an etching stopper layer 12 on the surface of the glass substrate S (fig. 9).

Here, the target S22b having a composition necessary for forming the etching stopper layer 12 is replaced in advance. The composition of the film forming gas required for forming the etching stopper layer 12 is switched so that the partial pressure thereof is controlled while supplying nitrogen gas or the like in different amounts from the gas introducing device S22e, and is within a predetermined range.

Specifically, a metal silicide film is formed as the etching stopper layer 12. As the metal silicide film, various films can be used, and in this embodiment, molybdenum silicide is used. At this time, in order to form molybdenum silicide, a reactive sputtering method can be used.

Molybdenum silicide has the property that it is very easily etched by an acid or alkali solution when nitrogen is not contained in the film. Therefore, when molybdenum silicide is used as an etching stopper film, molybdenum silicide containing nitrogen needs to be used.

When the molybdenum silicide is formed by the reactive sputtering method, nitrogen containing nitrogen, nitrogen monoxide, nitrogen dioxide, or the like is used as the additive gas. Thereby, a molybdenum silicide containing nitrogen in the film can be formed. In addition, by controlling the gas flow rate of the additive gas, the content of nitrogen contained in the molybdenum silicide can also be controlled.

In the light-shielding layer forming step S03 shown in fig. 5, the inside of the film forming chamber S22 is evacuated by the high vacuum evacuation device S22f in the film forming chamber (vacuum processing chamber) S22 shown in fig. 4. Then, a sputtering gas and a reaction gas are supplied from the gas introduction device S22e to the film forming chamber S22, and a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S22 c. Further, a predetermined magnetic field may be formed in the target S22b by a magnetron magnetic circuit.

In the film forming chamber S22, ions of the sputtering gas excited by the plasma collide with the target S22b of the cathode electrode S22c, thereby flying particles of the film forming material. Then, the flying particles are bonded to the reaction gas and then adhere to the glass substrate S, thereby forming a light shielding layer 13 on the surface of the glass substrate S (fig. 10).

Here, the target S22b having a composition necessary for forming the light-shielding layer 13 is replaced in advance. The composition of the film forming gas required for forming the light shielding layer 13 is switched to a predetermined range by supplying nitrogen gas or the like in different amounts from the gas introducing device S22e and controlling the partial pressure.

The light-shielding layer 13 contains chromium as a main component. At this time, in order to reduce the reflectance of the light-shielding layer 13, an antireflection layer having a low refractive index and an increased oxygen concentration may be formed on the surface of the light-shielding layer.

Further, in addition to the deposition of the halftone layer 11, the etching stopper layer 12, and the light shielding layer 13, when another film is to be deposited, the film is deposited by sputtering under sputtering conditions such as a target and a gas, or the film is deposited by another film deposition method, thereby producing the mask blank MB of the present embodiment shown in fig. 1.

A halftone mask blank having an underlying structure in which a metal silicide film is used as an etching stopper film can be formed.

Next, a method of manufacturing the halftone mask M from the mask blank MB thus manufactured will be described.

Fig. 11 to 18 are sectional views showing a manufacturing process of a halftone mask using the mask blank according to the present embodiment.

As shown in fig. 5, the method for manufacturing the halftone mask M according to the present embodiment includes: a photoresist layer forming process S04a, a resist pattern forming process S04b, a transmissive pattern forming process S04c, a cleaning process S04d, a photoresist layer forming process S05a, a resist pattern forming process S05b, a light shielding pattern forming process S05c, an etching stop pattern forming process S05d, and a cleaning process S05 e.

In the photoresist layer forming step S04a shown in fig. 5, a photoresist layer PR1 is formed on the light shielding layer 13 as the uppermost layer of the mask blank MB (fig. 11). The photoresist layer PR1 may be a positive type or a negative type, and may be a positive type. As the photoresist layer PR1, a liquid resist, a bonding film, or the like is used.

In the resist pattern forming step S04b shown in fig. 5, the photoresist layer PR1 is exposed to light and developed, whereby a photoresist pattern PR1p having a predetermined pattern shape (opening pattern) is formed on the light shielding layer 13 (fig. 12).

The photoresist pattern PR1p functions as an etching mask for the light-shielding layer 13, the etching stopper layer 12, and the halftone layer 11, and the shape thereof can be determined as appropriate according to the etching patterns of the halftone layer 11, the etching stopper layer 12, and the light-shielding layer 13.

For example, the resist pattern PR1a is set to a shape corresponding to the halftone area M2 and the light shielding area M3 except for the transmissive area M1 where the glass substrate S is exposed.

Next, as a transmissive pattern forming step S04c shown in fig. 5, the light-shielding layer 13, the etching stopper layer 12, and the halftone layer 11 are wet-etched in this order with a predetermined etching solution through the photoresist pattern PR1 p.

In this case, a chromium etchant, for example, an etchant containing cerium ammonium nitrate may be used for etching the chromium-containing light-shielding layer 13 and halftone layer 11.

In addition, as for the etching solution of the etching stopper layer 12, different etching agents, for example, a material containing at least one fluoride selected from hydrofluoric acid, silicofluoric acid, and ammonium bifluoride and at least one oxidizing agent selected from hydrogen peroxide, nitric acid, and sulfuric acid may be used.

Thereby, the light-shielding layer transmissive pattern 13p0, the etching stopper transmissive pattern 12p0, and the halftone pattern 11p are formed (fig. 13).

Next, in a cleaning step S04d shown in fig. 5, the photoresist pattern PR1p is removed with a predetermined cleaning liquid.

As the cleaning liquid, a mixed liquid of sulfuric acid and hydrogen peroxide or ozone water can be used.

In this state, the mask blank MB has the light-shielding layer transmissive pattern 13p0, the etching stopper transmissive pattern 12p0, the region where the halftone pattern 11p is formed, and the transmissive region M1 where the glass substrate S is exposed (fig. 14).

Next, as a photoresist layer forming step S05a shown in fig. 5, a photoresist layer PR2 is formed on the light-shielding layer transmissive pattern 13p0 as the uppermost layer of the mask blank MB. At this time, a photoresist layer PR2 is also formed in the transmissive area M1 (fig. 15).

The photoresist layer PR2 may be a positive type or a negative type, and may be a positive type. As the photoresist layer PR1, a liquid resist was used.

Next, as a resist pattern forming step S05b shown in fig. 5, the photoresist layer PR2 is exposed and developed, thereby forming a photoresist pattern PR2p on the light-shielding layer transmissive pattern 13p0 (fig. 16).

The photoresist pattern PR2p functions as an etching mask for the light-shielding layer transmissive pattern 13p0 and the etching stop layer transmissive pattern 12p 0.

The photoresist pattern PR2p may be appropriately shaped according to the etching pattern of the half-tone region M2 of the light-shielding layer transmission pattern 13p0, the etching stop layer transmission pattern 12p0 removed.

For example, the resist pattern PR2p is set to have a shape having an opening width corresponding to the opening width dimensions of the light-shielding pattern 13p and the etching stopper pattern 12p formed in the halftone region M2.

Next, as the light-shielding pattern forming step S05c shown in fig. 5, a step of wet etching the light-shielding layer transmissive pattern 13p0 with a predetermined etching solution (etchant) through the photoresist pattern PR2p is started.

In etching the light-shielding layer transmissive pattern 13p0, it is important that the etching stopper layer transmissive pattern 12p0 is not etched by the etching liquid of the light-shielding layer transmissive pattern 13p 0.

In the case of using the light-shielding layer transmissive pattern 13p0 containing chromium as a main component, an etching solution containing cerium ammonium nitrate may be used as the etching solution.

Further, cerium ammonium nitrate containing an acid such as nitric acid or perchloric acid is preferably used.

A mixed solution of ammonium ceric nitrate and perchloric acid is generally used as the etching solution.

Here, the etching stopper transmissive pattern 12p0 has higher resistance to the etching liquid than the light shielding layer transmissive pattern 13p 0. Therefore, first, only the light-shielding layer transmissive pattern 13p0 is patterned to form the light-shielding pattern 13 p.

The light blocking pattern 13p has an opening width corresponding to the photoresist pattern PR2p, and is removed in a shape corresponding to the half-tone region M2. The light-shielding pattern 13p is formed in a shape corresponding to the light-shielding region M3 (fig. 17).

At this time, since the etching stopper transmission pattern 12p0 has a desired selection ratio for the etching liquid, the etching rate is set to be extremely small. Therefore, the etch stop layer transmissive pattern 12p0 has sufficient etching resistance. Therefore, the halftone layer 11 having Cr of the same system as the light-shielding layer 13 is not damaged.

Next, as the etching stop pattern forming step S05d shown in fig. 5, a step of wet etching the etching stop layer transmissive pattern 12p0 with a predetermined etching solution through the photoresist pattern PR2p and the light shielding pattern 13p is started.

When the etching stopper layer 12 is MoSi, as the etching solution, a material containing at least one fluoride selected from fluorine-based hydrofluoric acid, silicofluoric acid, and ammonium bifluoride and at least one oxidizing agent selected from hydrogen peroxide, nitric acid, and sulfuric acid is preferably used.

In the wet etching of the etching stopper transmission pattern 12p0, in the halftone area M2 not covered with the light shielding pattern 13p, the etching stopper transmission pattern 12p0 is etched and forms the etching stopper pattern 12p (fig. 18).

The etching of the etching stopper layer 12 is terminated at the time when the etching stopper layer transmissive pattern 12p0 is etched to expose the halftone layer 11. Thereby, the halftone pattern 11p is exposed in the halftone area M2.

Next, as a cleaning process S05e shown in fig. 5, the photoresist pattern PR2p is removed.

At this time, in the light-shielding region M3 where the light-shielding patterns 13p are laminated, the washing water does not contact the halftone pattern 11 p. In contrast, in the halftone area M2, the wash water comes into contact with the halftone pattern 11 p.

In the cleaning of the halftone pattern 11p, the chemical-resistant layer 11a is disposed on the exposed surface.

The chemical-resistant layer 11a has chemical resistance to a cleaning liquid that is a mixed liquid of sulfuric acid and hydrogen peroxide or ozone water by having the above-described composition ratio of oxygen and the like. Therefore, the chemical-resistant layer 11a prevents the optical property layer 11b from being changed in film thickness and optical properties by the cleaning liquid in the cleaning step S05 e.

Therefore, in the cleaning step S05e, the chemical-resistant layer 11a can suppress the occurrence of variations in film thickness and optical characteristics caused by the cleaning liquid in the halftone pattern 11 p.

Thus, the optical characteristics of the halftone pattern 11p can be ensured by the optical characteristic layer 11 b.

Thus, as shown in fig. 2, the halftone mask M in which the transmissive region M1, the halftone region M2, and the light-shielding region M3 are formed can be obtained by having the predetermined light-shielding pattern 13p, the etching stop pattern 12p, and the halftone pattern 11p having the desired optical characteristics, which are optically set.

Alternatively, in the above-described process steps, after the molybdenum silicide film serving as the etching stopper layer 12 is processed, the halftone layer 11 containing chromium as a main component is etched using the molybdenum silicide film as a mask. After that, the step of processing the light-shielding layer 13, the etching stopper layer 12, and the halftone layer 11 may be completed by peeling off the resist layer.

Here, it is also possible to form only the pattern of the halftone layer 11 by etching only the light-shielding layer transmission pattern 13p0 and the etch stop layer transmission pattern 12p 0.

According to the mask blank MB of the present embodiment, as shown in fig. 1, the halftone layer 11 includes the chemical-resistant layer 11a and the optical property layer 11b, and thus a halftone mask M having desired optical properties can be manufactured.

Further, by forming the base halftone layer 11A in the base halftone layer forming step S01A and subjecting the base halftone layer 11A to the oxidation treatment in the oxidation treatment step S01b, the halftone layer 11 having suppressed variations in chemical resistance and optical characteristics can be formed.

Thus, the halftone mask M having desired optical characteristics can be manufactured by simply adding the oxidation step S01b to the conventional manufacturing steps.

Further, according to the mask blank MB of the present embodiment, as shown in fig. 2, the chemical resistance and the suppression of the variation in the optical characteristics in the cleaning step S05e can be simultaneously maintained, and the halftone mask M having desired optical characteristics can be manufactured.

Hereinafter, a mask blank, a half-tone mask, a manufacturing method, and a manufacturing apparatus according to a second embodiment of the present invention will be described with reference to the drawings.

Fig. 26 to 37 are flowcharts showing a method of manufacturing a halftone mask according to the present embodiment, and fig. 38 is a flowchart showing a method of manufacturing a mask blank and a halftone mask according to the present embodiment.

In the present embodiment, the difference from the first embodiment is the lamination position of the halftone layer, and the same reference numerals are given to the structures corresponding to the first embodiment except for the above, and the description thereof is omitted.

As shown in fig. 33, the mask blank MB according to the present embodiment is composed of a transparent substrate S, a light-shielding layer 13 formed on the transparent substrate S, and a halftone layer 11 formed on the light-shielding layer 13.

The light-shielding layer 13 may be a light-shielding pattern 13 p.

The halftone layer 11 has a chemical-resistant layer 11a having a composition ratio of oxygen higher than a composition ratio of chromium and a composition ratio of nitrogen at a position that is the outermost surface in the thickness direction. Further, the halftone layer 11 has an optical characteristic layer 11b having a composition ratio of oxygen lower than that of chromium and that of nitrogen at a position adjacent to the transparent substrate S and the light-shielding pattern 13p in the thickness direction.

The composition ratio in the halftone layer 11 is the same as that in the first embodiment described above.

As shown in fig. 37, the half-tone mask M according to the present embodiment includes a mask blank MB, a transmissive region M1, a half-tone region M2, and a light-shielding region M3.

The halftone area M2 is an area where a halftone pattern 11p patterned only by the halftone layer 11 in the mask blank MB is formed on the glass substrate (transparent substrate) S.

The light-shielding region M3 is a region in which the light-shielding layer 13 and the halftone layer 11 in the mask blank MB are patterned, and the light-shielding pattern 13p and the halftone pattern 11p are laminated.

As shown in fig. 38, the method for manufacturing a mask blank and a halftone mask according to the present embodiment includes: the method includes a substrate preparation step S00, a light-shielding layer forming step S011, a photoresist layer forming step S012a, a resist pattern forming step S012b, a light-shielding pattern forming step S012c, a cleaning step S012d, a base halftone layer forming step S013a, an oxidation treatment step S013b, a photoresist layer forming step S014a, a resist pattern forming step S014b, a transmissive pattern forming step S014c, and a cleaning step S014 d.

Here, in the description of the method for manufacturing a mask blank in the present embodiment, the process of the manufacturing apparatus S20 shown in fig. 4 will be described as in the first embodiment. In the case where the mask blank MB is manufactured by the manufacturing apparatus S10 shown in fig. 3, the reference numeral of the number S20 is read by being changed to the number S10, and the unloading chamber S25 is read by being changed to the loading and unloading chamber S11, and the like. In the present embodiment, the operation in the manufacturing apparatus S20 is appropriately omitted.

In the substrate preparation step S00 shown in fig. 38, a glass substrate S is prepared (fig. 26). Then, the transparent substrate S is carried into a film forming chamber (vacuum processing chamber) S22 through a loading chamber S21 shown in fig. 4. In the film forming chamber (vacuum processing chamber) S22, the transparent substrate S is supported by the substrate holding device S22 a.

In the light shielding layer forming step S011 shown in fig. 38, in the film forming chamber (vacuum processing chamber) S22 shown in fig. 4, a sputtering gas and a reaction gas are supplied from the gas introducing device S22e to the film forming chamber S22, and a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S22 c. Further, a predetermined magnetic field may be formed in the target S22b by a magnetron magnetic circuit.

In the film forming chamber S22, ions of the sputtering gas excited by the plasma collide with the target S22b of the cathode electrode S22c, thereby flying particles of the film forming material. Then, the flying particles are bonded to the reaction gas and then adhere to the glass substrate S, thereby forming the light shielding layer 13 on the surface of the glass substrate S (fig. 27).

The light-shielding layer 13 contains chromium as a main component. Here, the target S22b having a composition necessary for forming the light-shielding layer 13 is replaced in advance. The composition of the film forming gas required for forming the light shielding layer 13 is switched so that different amounts of nitrogen gas and the like are supplied from the gas introducing device S22e and the partial pressure thereof is controlled to fall within a predetermined range.

After that, the glass substrate S is carried out to the outside through the unloading chamber S25 shown in fig. 4.

As a photoresist layer forming step S012a shown in fig. 38, a photoresist layer PR1 is formed on the light shielding layer 13 as the uppermost layer of the mask blank (fig. 28). The photoresist layer PR1 may be a positive type or a negative type, and may be a positive type. As the photoresist layer PR1, a liquid resist, a bonding film, or the like is used.

In the resist pattern forming step S012b shown in fig. 38, the photoresist layer PR1 is exposed to light and developed, whereby a photoresist pattern PR1p having a predetermined pattern shape (opening pattern) is formed on the light shielding layer 13 (fig. 29).

The photoresist pattern PR1p functions as an etching mask for the light-shielding layer 13, and can be appropriately shaped according to the etching pattern of the light-shielding layer 13.

For example, the photoresist pattern PR1p is set to a shape corresponding to the light shielding region M3 except for the transmissive region M1 and the halftone region M2 where the glass substrate S is exposed.

Next, as a light-shielding pattern forming step S012c shown in fig. 38, the light-shielding layer 13 is wet-etched with a predetermined etching solution through the photoresist pattern PR1p to form a light-shielding pattern 13p (fig. 30).

In this case, a chromium etchant, for example, an etchant containing cerium ammonium nitrate may be used for etching the chromium-containing light-shielding layer 13.

Next, in a cleaning step S012d shown in fig. 38, the photoresist pattern PR1p is removed with a predetermined cleaning liquid. As the cleaning liquid, a mixed liquid of sulfuric acid and hydrogen peroxide or ozone water can be used.

The mask blank MB in this state has the light-shielding region M3 where the light-shielding pattern 13p is formed and the regions M1 and M2 where the glass substrate S is exposed (fig. 31).

Subsequently, the transparent substrate S is carried into a film forming chamber (vacuum processing chamber) S22 shown in fig. 4.

In the base halftone layer forming step S013a shown in fig. 38, in the film forming chamber (vacuum processing chamber) S22 shown in fig. 4, a sputtering gas and a reaction gas were supplied from the gas introduction device S22e to the film forming chamber S22, and a sputtering voltage was applied from an external power supply to the back plate (cathode electrode) S22 c. Further, a predetermined magnetic field may be formed in the target S22b by a magnetron magnetic circuit.

In the film forming chamber S22, ions of the sputtering gas excited by the plasma collide with the target S22b of the cathode electrode S22c, thereby flying particles of the film forming material. Then, the flying particles and the reactive gas are bonded and then attached to the glass substrate S and the light-shielding pattern 13p, whereby the base halftone layer 11A is formed on the surfaces of the glass substrate S and the light-shielding pattern 13p (fig. 32).

Here, the target S22b having a composition necessary for forming the base halftone layer 11A is replaced in advance. The composition of the film-forming gas necessary for forming the base halftone layer 11A is switched so that the partial pressure thereof is controlled by supplying nitrogen gas or the like in different amounts from the gas introduction device S22e, and the composition is within a predetermined range.

In this case, the formed base halftone layer 11A may have a predetermined composition ratio of oxygen, carbon, nitrogen, and chromium, respectively, in the thickness direction.

In the oxidation treatment step S013b shown in fig. 38, the transparent substrate S is carried from the film forming chamber S22 shown in fig. 4 into the oxidation treatment chamber S23.

The base halftone layer 11A is formed on the transparent substrate S. In the oxidation processing chamber S23, the transparent substrate S is held by the substrate holding device S23 a.

In the oxidation processing chamber S23, the inside of the oxidation processing chamber S23 is evacuated by the high vacuum evacuation device S23 f. Then, the oxidation processing gas is supplied from the gas introduction device S23e to the oxidation processing chamber S23.

The base halftone layer 11A sprayed with the excited oxidizing gas is oxidized to become a halftone layer 11 having predetermined oxygen composition ratio, carbon composition ratio, nitrogen composition ratio, and chromium composition ratio in the thickness direction (fig. 33).

In the halftone layer 11, a chemical-resistant layer 11a is formed at a position that is the outermost surface in the thickness direction. In addition, in the halftone layer 11, the optical characteristic layer 11b is formed at a position close to the transparent substrate S and the light-shielding pattern 13p in the thickness direction.

At this time, as the oxidation treatment gas, any gas may be used as long as it can oxidize the base halftone layer 11A containing chromium or the like, and oxygen, carbon dioxide, and N as a nitrogen oxidizing gas may be applied₂O, NO, etc.

In the oxidation step S01b, the oxidation state was precisely controlled, and the sheet resistance of the halftone layer 11 was set to 1.3X 10³Omega/sq or less.

Further, the sheet resistance of the halftone layer 11 may be set to 7.0 × 10²Omega/sq or more.

Next, as a photoresist layer forming step S014a shown in fig. 38, a photoresist layer PR2 is formed on the chemical-resistant layer 11a of the halftone layer 11 as the uppermost layer of the mask blank MB. At this time, a photoresist layer PR2 is formed in the transmissive region M1, the halftone region M2, and the light-shielding region M3 (fig. 34).

Next, as a resist pattern forming step S014b shown in fig. 38, the photoresist layer PR2 is exposed and developed, thereby forming a photoresist pattern PR2p on the chemical resistant layer 11a of the halftone layer 11 (fig. 35).

The photoresist pattern PR2p functions as an etching mask for the halftone layer 11.

The photoresist pattern PR2p may be appropriately shaped according to the etching pattern of the transmissive region M1 of the removal halftone layer 11.

The photoresist pattern PR2p is set to a shape corresponding to the half-tone region M2 and the light-shielding region M3 except for the transmissive region M1 where the glass substrate S is exposed.

Next, as the transmissive pattern forming step S014c shown in fig. 38, a step of wet etching the halftone layer 11 with a predetermined etching solution (etchant) through the photoresist pattern PR2p is started.

When the halftone layer 11 containing chromium as a main component is used, an etching solution containing cerium ammonium nitrate may be used as the etching solution.

The halftone pattern 11p has an opening shape corresponding to the photoresist pattern PR2p, and is removed to a shape corresponding to the halftone area M2 and the light-shielding area M3. The halftone pattern 11p is formed in a shape corresponding to the transmissive area M1 (fig. 36).

Next, as a cleaning process S014d shown in fig. 38, the photoresist pattern PR2p is removed.

At this time, in the light-shielding region M3 and the halftone region M2, the wash water comes into contact with the halftone pattern 11 p.

The chemical-resistant layer 11a has a chemical resistance to a cleaning liquid of a mixed solution of sulfuric acid and hydrogen peroxide or ozone water by having the above-described composition ratio of oxygen and the like. Therefore, in the cleaning step S014d, the chemical-resistant layer 11a prevents the optical property layer 11b from being changed in film thickness and optical properties by the cleaning liquid.

Therefore, in the cleaning step S014d, the chemical-resistant layer 11a can suppress the occurrence of changes in film thickness and optical characteristics caused by the cleaning liquid in the halftone pattern 11 p.

At the same time, by setting the sheet resistance of the halftone layer 11 as described above, the difference in transmittance due to the difference in wavelength of the exposure light in the halftone area M2 can be reduced.

Fig. 39 shows the relationship between the sheet resistance of the halftone layer 11 and the difference in transmittance due to the difference in wavelength of the exposure light in the halftone area M2, as will be described later.

As a result, as shown in fig. 37, a halftone mask M having a predetermined light-shielding pattern 13p that is optically set, a halftone pattern 11p having desired optical characteristics, and a transmission region M1, a halftone region M2, and a light-shielding region M3 formed therein can be obtained.

According to the mask blank MB of the present embodiment, as shown in fig. 33, the halftone layer 11 includes the chemical-resistant layer 11a and the optical characteristic layer 11b, and thus a halftone mask M having desired optical characteristics can be manufactured.

Further, by forming the base halftone layer 11A in the base halftone layer forming step S013a and subjecting the base halftone layer 11A to the oxidation treatment in the oxidation treatment step S013b, the halftone layer 11 having chemical resistance, suppressed fluctuation in optical characteristics, and suppressed transmittance difference due to wavelength can be formed.

Thus, a halftone mask M having desired optical characteristics can be manufactured by simply adding the oxidation step S013b to the conventional manufacturing steps. Further, the halftone mask M in which the etching stop pattern is not required to be formed can be manufactured without providing an etching stop layer.

Further, by setting the sheet resistance of the halftone layer 11, the transmittance difference in the halftone layer 11 due to the wavelength of the exposure light can be reduced. Thus, it is possible to manufacture the halftone mask M that suppresses the occurrence of the difference in transmittance due to the wavelength of the exposure light and easily copes with the complex wavelength versus the exposure light.

According to the present embodiment, a so-called top-mount halftone mask M in which the halftone layer 11 is formed on the light-shielding pattern 13p can be manufactured. Even when the halftone pattern 11p is formed in the top-mount type halftone mask M, the cleaning process S014d is performed using ozone, a mixture of sulfuric acid and hydrogen peroxide, or the like.

In the cleaning step S014d or the like, if the transmittance of the halftone mask is varied, a problem arises in that a desired shape cannot be obtained in a resist pattern as an exposure target when the pattern is formed using the mask.

Therefore, by using the halftone mask of the present embodiment, it is possible to reduce the transmittance difference (change in transmittance) at the exposure wavelength and to suppress the transmittance change in the halftone layer 11 after the cleaning step S014d using a chemical agent.

The upper half-tone mask is first formed with a chromium film as a light shielding layer 13 on a glass substrate. Then, in order to form a desired pattern, patterning of the chromium film is performed using a resist process. Then, the halftone layer 11 formed of a chromium film is formed. In this case, by applying the present invention, a halftone layer with less transmittance variation in the cleaning step can be formed.

Then, the resist process is continued to form the halftone layer into a desired pattern, thereby forming the top-mount halftone mask.

[ examples ] A method for producing a compound

Hereinafter, examples of the present invention will be described.

First, the production of a mask blank will be described as a specific example of the mask blank and the halftone mask of the present invention.

< Experimental example >

First, a semi-transmissive halftone film is formed on a glass substrate for forming a mask.

Here, first, a film having a composition ratio of chromium, oxygen, nitrogen, carbon, or the like similar to that of the conventional film is formed, and then, oxidation treatment is performed.

The halftone film formed at this time is preferably a film containing chromium, oxygen, nitrogen, carbon, and the like. By controlling the composition and thickness of chromium, oxygen, nitrogen, and carbon contained in the halftone film during film formation and oxidation treatment, a halftone film having a desired transmittance can be obtained.

Then, a metal silicide film is formed as an etching stopper layer. As the metal silicide film, various films can be used, and in the present embodiment, molybdenum silicide is used. At this time, in order to form molybdenum silicide, a reactive sputtering method may be used.

Molybdenum silicide has the property that it is very easily etched by an acid or alkali solution when nitrogen is not contained in the film. Therefore, when molybdenum silicide is used as the etching stopper, molybdenum silicide containing nitrogen is used.

Here, when the molybdenum silicide is formed by a reactive sputtering method, the nitrogen-containing molybdenum silicide in the film can be formed by using nitrogen, nitrogen monoxide, nitrogen dioxide, or the like containing nitrogen in the additive gas. In this case, the amount of nitrogen contained in the molybdenum silicide can also be controlled by controlling the gas flow rate of the additive gas.

Then, a light-shielding layer containing chromium as a main component is formed.

At this time, in order to reduce the reflectance of the light-shielding layer, an antireflection layer having a high oxygen concentration and a low refractive index is formed on the surface of the light-shielding layer. Thus, a halftone mask blank of an underlying structure using a metal silicide film as an etching stopper is formed.

In addition, when forming a halftone mask, a resist process is used first, and a light shielding film is processed into a desired pattern through process steps of resist coating, exposure, development, etching, and resist stripping. Here, when etching the light-shielding film, it is important that the etching stopper film is not etched by the etching liquid of the light-shielding film. When a light-shielding film containing chromium as a main component is used, a mixed solution of ammonium ceric nitrate and perchloric acid is generally used as an etching solution.

When molybdenum silicide is used as an etching stopper, the molybdenum silicide is not substantially etched by the etching solution of chromium, and therefore functions as a favorable etching stopper.

Next, the etching stopper film is processed by the resist process similarly for the molybdenum silicide film.

Here, the etching solution for etching the molybdenum silicide film is a solution containing hydrofluoric acid and an oxidizing agent.

After the processing of the molybdenum silicide film as the etching stopper film, the halftone film mainly containing chromium is etched using the molybdenum silicide film as a mask. Thereafter, the light shielding layer, the etching stopper layer, and the halftone film are processed by peeling off the resist film.

As described above, in the bottom half-tone mask M, the patterning process using the resist is required at least twice or more. Therefore, the number of processes for processing each film in the etching solution and the cleaning solution in the patterning process is increased as compared with the top-mounted halftone mask.

Therefore, the underlying halftone mask M in which the halftone layer 11 is formed before the light-shielding layer 13 is required to have high chemical resistance.

In addition, when the transmittance of the halftone layer 11 is set to be high such as 40% or more, the film thickness of the halftone layer 11 needs to be set to be thin. Therefore, if the chemical resistance of the halftone layer 11 is low, the transmittance changes greatly, and therefore, higher chemical resistance is required.

In addition, the importance of a flat halftone film that reduces the wavelength dependence of the transmittance of the halftone layer 11 is increasing.

In the exposure process of the panel in the FPD production, since the processing speed of exposure is very important, light of multiple wavelengths different from the exposure process in the semiconductor is used in the exposure process.

In general, the exposure is performed using light of g-line (436nm), h-line (405nm), or i-line (365nm), which are intense bright line spectra of a high-pressure mercury lamp. Therefore, it is preferable that the transmittances of these wavelengths are values as close to each other as possible.

Therefore, a metallic chromium film which is relatively less oxidized as a halftone film so far is generally used.

However, it was found that the following problems occur in the case of using a chromium film, in which oxidation does not occur relatively, as a halftone film: in a cleaning step or an ozone cleaning step using a mixed solution of sulfuric acid and hydrogen peroxide water (a mixed solution of sulfuric acid and hydrogen peroxide) used in the cleaning step as a mask, the transmittance of the halftone film changes due to etching of the halftone film.

On the other hand, although chemical resistance can be improved by enhancing oxidation of the halftone film, when the oxygen concentration in the film is too high, there is a problem that wavelength dependence of transmittance becomes large. In order to solve such problems, in the present example, the oxygen concentration of the surface of the halftone film is increased, the oxygen concentration of the surface is appropriately controlled, and the oxygen concentration is decreased in the depth direction of the halftone film, whereby the wavelength dependence of the transmittance is suppressed to a certain degree and the chemical resistance can be improved.

< Experimental example 1>

As experimental example 1, a halftone film having the same composition ratio, which is not different from a conventionally used halftone film, was formed.

In the case where the formed halftone film was not subjected to the oxidation treatment, the composition of the halftone film was evaluated by auger electron spectroscopy.

The results are shown in FIG. 19.

Further, the halftone film whose composition evaluation is shown in fig. 19 may be the base halftone layer 11A described above.

< Experimental example 2>

As experimental example 2, after the same halftone film as in experimental example 1 was formed, oxidation treatment was performed using NO gas.

In this case, the composition of the oxidized halftone film was evaluated by auger electron spectroscopy, as in experimental example 1.

The results are shown in FIG. 20.

< Experimental example 3>

As experimental example 3, after the same halftone film as in experimental example 1 was formed, CO was used₂The gas is subjected to an oxidation treatment.

The results are shown in FIG. 21.

From these results, it can be seen that the oxygen concentration in the film of the halftone film of experimental example 1 whose composition was evaluated is reduced in fig. 19. In addition, it can be seen that the use of NO gas and CO as in Experimental examples 2 and 3₂The gas is subjected to oxidation treatment, whereby the oxygen concentration on the surface of the halftone film can be increased.

Further, as in experimental example 2 and experimental example 3, by using NO gas and CO₂The gas is subjected to an oxidation treatment, thereby increasing the thickness of the halftone film. The positions in the thickness direction of the halftone film corresponding to these positions are indicated by arrows in fig. 19 to 22, respectively.

Further, by comparing experimental example 2 of fig. 20 with experimental example 3 of fig. 21, it was found that CO was used₂In the case of the gas experimental example 3, the oxygen concentration of only the surface of the halftone film can be increased by the oxidation treatment using the NO gas experimental example 2.

This is considered to be because when CO is excited by plasma₂The oxidation force is higher for gas than for NO gas.

Further, the transmittance of the halftone film in the h-line, the difference in transmittance between the g-line and the i-line, the film thickness, and the change in transmittance after washing with the sulfuric acid/hydrogen peroxide solution were measured.

These results are shown in table 1.

[ TABLE 1 ]

As can be seen from the results, in experimental examples 2 and 3 in which the oxidation treatment was performed, the transmittance change in the halftone film before and after the cleaning with the mixed solution of sulfuric acid and hydrogen peroxide was suppressed.

In addition, in experimental examples 2 and 3 in which the oxidation treatment was performed, the difference in transmittance between the g-line and the i-line was larger than that of the halftone film of experimental example 1 in which the oxidation treatment was not performed.

Further, with CO₂The halftone film of experimental example 2 in which the oxidation treatment was performed with NO gas was able to reduce the difference in transmittance between the g-line and the i-line, compared to the halftone film of experimental example 3 in which the oxidation treatment was performed with gas. This is considered to be because oxidation of the interior of the halftone film can be suppressed by the oxidation treatment in the NO gas, and oxidation of the halftone film surface can be enhanced.

Next, in order to obtain a halftone film having strong chemical resistance and little wavelength dependence of transmittance, the halftone film was subjected to oxidation treatment using various NO gases to change the surface oxygen concentration in the halftone film, and the transmittance changes before and after the formed halftone film was cleaned with a mixture of sulfuric acid and hydrogen peroxide solution were examined.

< Experimental example 4>

As experimental example 4, the surface oxygen concentration of the halftone film was changed, and the relationship between the surface oxygen concentration of the halftone film and the transmittance change before and after the cleaning with the sulfuric acid/hydrogen peroxide mixture was examined.

The results are shown in FIG. 22.

< Experimental example 5>

As experimental example 5, the relationship between the surface nitrogen concentration of the halftone film and the transmittance change before and after the cleaning with the sulfuric acid/hydrogen peroxide solution was examined.

The results are shown in FIG. 23.

From the results of experimental examples 4 and 5, it was found that in order to improve the resistance to the mixed solution of sulfuric acid and hydrogen peroxide, the oxygen concentration of the halftone film surface is preferably 40% or more, and the nitrogen concentration is preferably 20% or less.

Further, the preferable ranges of the composition ratios are shown in fig. 22 and 23, respectively.

Next, in order to obtain a halftone film having strong chemical resistance and little wavelength dependence of transmittance, the halftone film was subjected to oxidation treatment using various NO gases to change the surface oxygen concentration of the halftone film, and the change in spectral transmittance characteristics of the formed halftone film was examined.

< Experimental example 6>

Similarly to experimental example 4, the surface oxygen concentration in the halftone film was changed, and as experimental example 6, the relationship between the surface oxygen concentration of the halftone film and the difference between the transmittances of the g-line and i-line was examined.

The results are shown in FIG. 24.

< Experimental example 7>

Similarly to experimental example 5, the surface nitrogen concentration of the halftone film was changed, and as experimental example 7, the relationship between the surface nitrogen concentration of the halftone film and the difference between the transmittances of the g-line and i-line was examined.

The results are shown in FIG. 25.

The difference between the transmittance of g-line and the transmittance of i-line obtained in the halftone mask is generally about 0.6%.

From the results of experimental examples 6 and 7, it was found that the surface of the halftone film satisfying the above criteria had an oxygen concentration of 55% or less and a nitrogen concentration of 15% or more.

Further, the preferable ranges of the composition ratios are shown in fig. 24 and 25, respectively.

As a result of the above-described studies, it has been found that in order to obtain a halftone film having high chemical resistance and small wavelength dependence of transmittance, it is preferable to increase the oxygen concentration on the surface of the halftone film and decrease the oxygen concentration in the film by subjecting the halftone film to an oxidation treatment using NO gas.

Further, it was found that the oxygen concentration of the surface of the halftone film is preferably 40% or more and 55% or less, and the nitrogen concentration is preferably 15% or more and 20% or less.

It has been found that by applying this halftone film to an underlying halftone mask, a halftone mask with little change in transmittance and little wavelength dependence of transmittance can be obtained even if chemical treatment necessary in the mask manufacturing process is performed.

In the above-described embodiments, the bottom half-tone mask having a large number of chemical treatment steps was described as an example, but the present invention can also be applied to a top half-tone mask in which a half-tone film is formed on a light-shielding film.

Thus, an upper half-tone mask having high chemical resistance and little wavelength dependence of transmittance can be manufactured.

In the above-described embodiment, the halftone layer 11 is formed by subjecting the base halftone layer to the oxidation process, but the halftone layer 11 may be formed by supplying the oxidation process gas during the film formation so that the oxygen concentration is the above-described composition ratio.

In this case, an oxidation process gas supply unit capable of supplying an oxidation process gas may be provided in the film forming chambers S12 and S22, and the oxidation process chambers S13 and S23 may not be provided.

< Experimental example 8>

In experimental example 8, the same halftone films as in experimental examples 1 to 7 were formed, and then oxidation treatment was performed using NO gas or the like. Further, the sheet resistance was measured on the halftone film after the oxidation treatment.

In this experimental example 8, the oxidation conditions were changed so that the sheet resistance was 0.7X 10³Ω/sq～1.3×10³And omega/sq.

Further, in the halftone film with the sheet resistance changed, the transmittance was measured using the light of the g line (436nm) and the light of the i line (365nm), and the value of "g line transmittance" - "i line transmittance", that is, the value of the difference between the g line transmittance and the i line transmittance (Δ T (g-i line) (%)) was calculated.

The results are shown in FIG. 39.

From this result, it was found that the relationship between the transmittance difference of the g-line (436nm) and the i-line (365nm) and the sheet resistance using the halftone film of the present invention is as follows: as the sheet resistance increases, the difference in transmittance between the g-line and the i-line becomes larger.

The halftone film of the present invention has a large variation in oxygen concentration in the film thickness direction, and the oxygen concentration in the vicinity of the halftone film surface is high. Therefore, it was found that as the oxidation conditions in the oxidation step are enhanced, the oxygen concentration increases, and the sheet resistance of the halftone film increases accordingly.

From this, it was found that the effect of the present invention can be obtained by changing the resistivity of the halftone film in the depth direction, increasing the resistivity in the vicinity of the surface of the halftone film, and decreasing the resistivity of the lower layer.

Further, it is clear that the halftone film of the present invention can suppress a change in the transmittance difference before and after wet etching.

Industrial applicability

Examples of applications of the present invention include masks and mask blanks for semiconductors and flat panel displays.

Claims

1. A mask blank is characterized by comprising:

a transparent substrate;

a halftone layer laminated on a surface of the transparent substrate and containing Cr as a main component;

an etch stop layer laminated on the halftone layer; and

a light-shielding layer which is laminated on the etching stop layer and contains Cr as a main component,

the halftone layer has: a chemical-resistant layer located at the outermost surface position in the thickness direction, the composition ratio of oxygen being higher than the composition ratio of chromium and the composition ratio of nitrogen; and an optical characteristic layer located in a position adjacent to the transparent substrate in a thickness direction, wherein a composition ratio of oxygen is lower than a composition ratio of chromium and a composition ratio of nitrogen, and optical characteristics are ensured.

2. A mask blank is characterized by comprising:

a transparent substrate;

a light shielding layer which is laminated on the surface of the transparent substrate and mainly contains Cr; and

a halftone layer laminated on the light-shielding layer and containing Cr as a main component,

3. The mask blank according to claim 1 or claim 2,

in the halftone layer, a composition ratio of oxygen decreases from a position on an outermost surface in a thickness direction to a position adjacent to the transparent substrate.

4. The mask blank according to claim 1 or claim 2,

in the half-tone layer, a color filter is formed,

the composition ratio of oxygen in the chemical-resistant layer is set to be 4 times larger than the composition ratio of the smallest oxygen in the optical characteristic layer.

5. The mask blank according to claim 1 or claim 2,

in the halftone layer, the sheet resistance was set to 1.3 × 10³Omega/sq or less.

6. A method for manufacturing a mask blank, characterized by manufacturing the mask blank according to any one of claims 1 to 5, the method comprising:

a film forming step of laminating a base halftone layer containing Cr as a main component; and

and an oxidation treatment step of oxidizing the base halftone layer formed in the film formation step to form the halftone layer.

7. The method for manufacturing a mask blank according to claim 6, wherein in the oxidation treatment step, the oxidation treatment of the base halftone layer is performed by an excited oxidation treatment gas.

8. The method according to claim 7, wherein said oxidizing gas in said oxidizing step is nitrogen oxide.

9. A method for manufacturing a mask blank, characterized by manufacturing the mask blank according to any one of claims 1 to 5, the method comprising:

a film forming step of laminating the halftone layer containing Cr as a main component.

10. A method of manufacturing a halftone mask, characterized by manufacturing a halftone mask using the mask blank according to any one of claims 1 to 5, the method comprising:

patterning the halftone layer through a mask having a predetermined pattern; and

and a cleaning step of removing the mask.

11. The method of manufacturing a halftone mask according to claim 10,

in the cleaning step, a mixed solution of sulfuric acid and hydrogen peroxide or ozone water is used as the cleaning liquid.

12. A halftone mask manufactured by the manufacturing method of claim 10 or claim 11.

13. An apparatus for manufacturing a mask blank, which is used for the method for manufacturing a mask blank according to any one of claims 6 to 8, comprising:

a film forming section that forms the basic halftone layer; and

an oxidation processing section for performing oxidation processing on the base halftone layer,

the oxidation processing unit includes an excited gas supply unit capable of supplying an oxidized processing gas by exciting the oxidized processing gas.

14. An apparatus for manufacturing a mask blank, which is used for the method for manufacturing a mask blank according to claim 9, comprising:

a film forming section for forming the halftone layer,

the film forming section includes an excited gas supply section capable of exciting and supplying an oxidation process gas.