JP2008090254A - Photomask substrate, photomask and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photomask substrate, a photomask and a method for manufacturing a photomask in which a fine pattern can be formed with high accuracy by wet etching. <P>SOLUTION: The photomask substrate 2 comprises a transparent substrate 10, a semitransmissive layer 20 having semitransmissive property, and a light shielding layer 33 formed on the semitransmissive layer 20 and substantially shielding against irradiation light, wherein the semitransmissive layer 20 is made of titanium nitride (TiNx, 0<x<1.33) that is insoluble or hardly soluble with an etching liquid (A) and easily soluble with an etching liquid (B) compared with the light shielding layer 33. The light shielding layer 33 is made of metal chromium (Cr) that is easily soluble with the etching liquid (A) and insoluble or hardly soluble with the etching liquid (B) compared with the semitransmissive layer 20. Since etching durability of each layer against etching liquids differs from others, the semitransmissive layer 20 and the light shielding layer 33 can be selectively etched without damaging other layers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photomask substrate having a transflective layer, a photomask, and a method for manufacturing the same, and in particular, fine patterning such as LSI, display elements for flat panel display devices such as LCD, PDP, and EL, and fine scattering. The present invention relates to an antireflection plate using unevenness, a diffuse reflection plate with or without fine particles, a microlens array, a photomask substrate for forming a pattern used for surface modification such as forming an array of unevenness, a photomask, and a manufacturing method thereof.

With the development of liquid crystal display elements (reflection type, transmission type and transflective type), plasma display elements, organic EL (electroluminescence) display elements, and other flat panel display elements, the size of these display elements in production sites Various types of photomasks having different patterns and the like are used.
For example, in a TFT (Thin Film Transistor) manufacturing process in the formation of a liquid crystal display element, depending on the manufacturing method, generally 3 to 5 different patterning photomasks are required. Further, on the color filter side arranged to face the liquid crystal display element, a photomask corresponding to the liquid crystal display element is required for forming the black matrix and for forming the colored layer.

  In photomasks used for forming fine patterns such as LSIs, halftone masks are used for the purpose of improving pattern accuracy (for example, Patent Documents 1 to 9). The halftone mask is a photomask in which a semitransparent layer (halftone) is formed between a transmissive portion and a light shielding portion. The thickness of the semi-transmissive layer is designed so that the phase is inverted by λ / 2 or shifted by ± λ / 4 in accordance with the exposure wavelength to be used. Thereby, the diffraction of the light which arises between adjacent patterns is prevented, and a light intensity difference becomes clear between the edge part of the light-shielding part of a mask, and a permeation | transmission part. In addition, since it is difficult for moire and halation to occur, the resolution can be improved. In addition, there is a method (gray tone mask) that obtains the same effect as halftone by forming a fine continuous stripe pattern.

  As a method of manufacturing such a photomask with halftone, first, a photomask substrate (photomask blanks) on which a first layer (semi-transmissive layer or light shielding layer) is formed is covered with a resist and exposed. After patterning, the resist is removed and washed, and a second layer (light-shielding layer or semi-transmissive layer) is formed again using a vacuum apparatus or the like. A method of patterning two layers is known (see, for example, Patent Documents 3 and 9). As another manufacturing method, there is also known a method in which a thin film having a homogeneous or heterogeneous multilayer structure is first formed and then each pattern is formed by dry etching (for example, Patent Documents 2 and 5).

JP-A-7-209849 Japanese Patent Laid-Open No. 9-127777 Japanese Patent Laid-Open No. 2001-27801 JP 2001-83687 A JP 2001-312043 A JP 2003-29393 A JP 2003-322949 A Japanese Patent Laid-Open No. 2004-29746 JP 2006-18001 A

  In this conventional method, after patterning is performed on the first layer formed using a vacuum apparatus or the like, the second layer is formed again using the vacuum apparatus or the like to perform patterning. Therefore, it is necessary to perform a film forming process using a vacuum apparatus or the like at least twice. For this reason, there are inconveniences that the number of processes necessary for manufacturing a photomask increases and the manufacturing cost increases.

  Usually, photomask patterns are formed by dry etching in which a layer on a photomask substrate is irradiated with ions by plasma such as reactive gas or laser light, and etching is performed using a corrosive etching solution (chemical solution). There are two types of etching methods: wet etching (also referred to as wet etching) that chemically corrodes the layer. Of these, the dry etching method is generally used for pattern formation of the photomask.

  However, dry etching has various technical problems associated with the increase in size and mass production of photomasks. For example, in the direct drawing process by dry etching, the drawing area increases with the enlargement of the photomask, so that the drawing time by an electron beam, a laser, etc. increases, and the tact time of photomask manufacturing can be improved. It was difficult. In addition, as the size of the photomask increases, it is necessary to increase the size of facilities such as a vacuum tank and a gas type switching device, which increases the burden on the facility and increases the cost required for manufacturing the photomask. There was also inconvenience. Furthermore, since the number of substrates that can be processed at one time is limited, it is not suitable for mass production.

On the other hand, in wet etching, equipment and etching liquid are generally inexpensive, and pattern formation by etching is possible in a shorter time than dry etching. It is convenient for mass production and production in a short time.
However, in wet etching, when one of the stacked layers is etched, a part of the other layer is dissolved, or another layer is formed at the interface or grain boundary between the other layer and the etching solution. The reaction between the substance and the etching solution may cause a chemical heterogeneous structure, which may cause damage to other layers. For this reason, high-precision microfabrication is difficult. In particular, when manufacturing a mask in which different types of layers are laminated, such as a halftone mask in which a phase shift layer and a light shielding layer are laminated, only the target layer is selectively etched without damaging other layers. Was technically difficult.

In view of the above problems, an object of the present invention is to provide a photomask capable of forming two kinds of fine patterns on the surface of a transparent substrate in a short time and at low cost by a wet etching method that has been difficult with conventional photomask manufacturing techniques. It is to provide a substrate.
Another object of the present invention is to provide a photomask having two kinds of fine patterns formed in a short time and at low cost by sequentially etching a photomask substrate by wet etching, and a method for manufacturing the photomask. It is in.

  According to the photomask substrate of the present invention, the object is to form a transparent substrate, a first layer that is formed on the transparent substrate and is semi-transmissive to irradiation light, and is formed on the first layer. A second layer that substantially blocks the irradiation light, a light-shielding portion that exposes a light-shielding pattern formed by the second layer, and a semi-transmissive pattern formed by the first layer Is a photomask substrate capable of forming a translucent portion exposed on the surface and a transparent portion where the transparent substrate is exposed on the surface, wherein the first layer is more first than the second layer. It is insoluble or hardly soluble in the etching solution and easily soluble in the second etching solution, and the second layer is more soluble in the first etching solution than the first layer. And insoluble or hardly soluble in the second etching solution. It is resolved by the.

Thus, according to the photomask substrate of the present invention, the first layer is insoluble or hardly soluble in the first etching solution and easier in the second etching solution than the second layer. On the other hand, the second layer is more soluble in the first etching solution than the first layer and insoluble or hardly soluble in the second etching solution. Therefore, the second layer can be selectively etched using the first etching solution, and the first layer can be selectively etched using the second etching solution.
Then, by selectively etching the first layer and the second layer with different etching solutions, two types of patterns, a semi-transmissive pattern and a light shielding pattern, are formed on the transparent substrate, and the light shielding portion where the light shielding pattern is exposed. Then, it is possible to form the three regions of the semi-transmissive portion where the semi-transmissive pattern is exposed on the surface and the transparent portion where the transparent substrate is exposed on the surface by wet etching using an etching solution.
Thus, in the photomask substrate of the present invention, the first layer and the second layer have resistance to different etching solutions, and the first layer can be obtained by utilizing the difference in resistance. The second layer is hardly modified or damaged by the second etching solution that solubilizes, and conversely, the first layer is modified by the first etching solution that solubilizes the second layer. And is hardly damaged. For this reason, it becomes possible to manufacture a photomask on which a fine pattern is formed with high accuracy.

The first layer is preferably formed directly on the transparent substrate.
In general, a metal compound layer or the like is interposed between the transparent substrate and the first layer in order to improve the adhesion between the two, but by directly forming the first layer on the transparent substrate, There is no need to interpose a metal compound layer. For this reason, it becomes possible to reduce the man-hour for forming a metal compound layer on the surface of a transparent substrate, and the material for it, and can improve the production efficiency of the board | substrate for photomasks.

  The first layer is preferably formed on the transparent substrate through a metal compound layer having a transmittance of 70% or more and less than 100%.

Thus, by forming the first layer on the transparent substrate through the metal compound layer having a transmittance of 70% or more and less than 100%, the light transmitted through the transparent substrate is hardly reflected and the first layer In addition to improving the adhesion to the first layer, it is possible to protect the surface of the transparent substrate from damage caused by the etchant during the production of the photomask.
At this time, the refractive index of the metal compound layer is more preferably equal to or lower than the refractive index of the substrate.

The first etching solution is preferably a mixed solution of cerium ammonium nitrate, perchloric acid and water.
Further, the second etching solution is preferably a mixed solution of potassium hydroxide, hydrogen peroxide and water.
The first layer preferably contains as a main component one or more components selected from the group consisting of titanium, titanium nitride, and titanium oxynitride.
Furthermore, the second layer is preferably composed mainly of one or more components selected from the group consisting of chromium, chromium oxide, chromium nitride, and chromium oxynitride.

Thus, by appropriately selecting the first etching solution, the second etching solution, the first layer, and the second layer, the selectivity of the etching solution with respect to each layer is improved, and a more accurate and fine pattern is obtained. Can be formed.
In particular, one or more components selected from the group consisting of titanium, titanium nitride, and titanium oxynitride are insoluble in a mixed solution of cerium ammonium nitrate, perchloric acid, and water as the first etching solution. Alternatively, it is hardly soluble and is easily soluble in a mixed solution of potassium hydroxide, hydrogen peroxide and water as the second etching solution. On the other hand, one or two or more selected from the group consisting of chromium, chromium oxide, chromium nitride, and chromium oxynitride is a mixture of cerium ammonium nitrate, perchloric acid, and water as the first etching solution. It is easily soluble and insoluble or hardly soluble in a mixed solution of potassium hydroxide, hydrogen peroxide and water as the second etching solution.
Therefore, by adopting titanium or titanium compound as the first layer and chromium or chromium compound as the second layer, the selectivity to each etching solution is improved, and a more precise and fine pattern can be formed. Is possible.
In particular, titanium nitride is highly resistant to chemicals such as acid and alkali, and therefore is not easily damaged by chemicals used in the etching process such as a resist removing solution. For this reason, it is possible to perform selective etching smoothly and to form a highly accurate and fine pattern.

  The second layer preferably includes a light shielding layer and an antireflection layer formed on the surface side of the light shielding layer.

Thus, it is preferable that the second layer includes the antireflection layer because an antireflection effect can be obtained and halation due to reflection of irradiation light during mask exposure is prevented.
In addition, since the second layer is formed of the light shielding layer and the antireflection layer, the light shielding layer and the antireflection layer can be etched together, and the light shielding pattern having the antireflection layer pattern formed on the surface can be obtained. It can be formed easily.

  Furthermore, in this case, the antireflection layer is preferably a layer mainly composed of one or two or more components selected from the group consisting of chromium oxide, chromium nitride, and chromium oxynitride.

  Thus, since the antireflection layer is formed of a layer mainly composed of one or two or more components selected from the group consisting of chromium oxide, chromium nitride, and chromic oxynitride having low reflectance, It is preferable because a high antireflection effect can be obtained and halation due to reflection of irradiation light during mask exposure is prevented.

  Furthermore, the first layer is a layer mainly composed of one or two or more components selected from the group consisting of chromium, chromium oxide, chromium nitride, and chromium oxynitride, and the second layer Is a layer mainly composed of one or more components selected from the group consisting of titanium, titanium nitride, and titanium oxynitride, and the first etching solution includes potassium hydroxide, hydrogen peroxide, and Even if the second etching solution is a mixed solution of cerium ammonium nitrate, perchloric acid and water, the selectivity to each etching solution is improved by the same action as described above. It becomes possible to form a highly accurate and fine pattern.

  The first layer and the second layer are preferably formed by a sputtering method, an ion plating method, or an evaporation method.

  Thus, by manufacturing the first layer and the second layer by a film forming technique such as a sputtering method, a photomask substrate having desired optical characteristics can be obtained by appropriately adjusting the film thickness and the like. Thus, a photomask having desired optical characteristics can be formed. In addition, by manufacturing by a film forming technique such as sputtering, it is possible to appropriately adjust physical characteristics such as chemical resistance and fastness of the photomask substrate.

According to the photomask of the present invention, the above-described problem is that a transparent substrate, a first layer that is formed on the transparent substrate and is semi-transmissive to irradiation light, and an irradiation formed on the first layer. A photomask formed by a photomask substrate comprising: a second layer that substantially blocks light;
The first layer is insoluble or hardly soluble in the first etching solution and more easily soluble in the second etching solution than the second layer, and the second layer is It is more soluble in the first etchant than the first layer and insoluble or hardly soluble in the second etchant, and the photomask is made of the first etchant by the first etchant. A light-shielding portion where a light-shielding pattern formed by etching the second layer is exposed on the surface, and a semi-transparent pattern formed by etching the first layer with the second etching solution is exposed on the surface. A transmissive part and a transparent part in which the second layer and the first layer are etched by the first etching liquid and the second etching liquid and the transparent substrate is exposed on the surface are formed. It is solved by.

As described above, according to the photomask of the present invention, the first layer is insoluble or hardly soluble in the first etching solution and more easily soluble in the second etching solution than the second layer. On the other hand, the second layer is more soluble in the first etching solution than the first layer, and is insoluble or hardly soluble in the second etching solution. Therefore, the second layer can be selectively etched using the first etching solution, and the first layer can be selectively etched using the second etching solution.
Then, by selectively etching the first layer and the second layer with different etching solutions, two types of patterns, a light shielding pattern and a semi-transmissive pattern, are formed on the transparent substrate, and the light shielding portion where the light shielding pattern is exposed. The three types of regions of the semi-transmissive portion where the semi-transmissive pattern is exposed on the surface and the transparent portion where the transparent substrate is exposed on the surface are formed on the surface of the transparent substrate by wet etching using an etchant.
Thus, according to the photomask of the present invention, since the difference in resistance between the first layer and the second layer with respect to the etching solution is used, the second layer is modified with the etching solution of the first layer. A photomask in which the first layer is hardly modified or damaged by the etching solution of the second layer, and has a high precision and a fine pattern is formed. It becomes possible to provide.

  According to the photomask manufacturing method described above, the problem is that the first resist coating step of coating the surface of the second layer with the resist and the mask on which the first mask pattern is formed are provided through the first mask. A first exposure process for exposing the resist coated in one resist coating process; a first resist removing process for removing an exposed portion of the resist after the first exposure process; and Etching the second layer exposed in the removed region with the first etchant to form the light-shielding pattern, and stripping the resist remaining in the first resist removing step The second resist coating step, the second resist coating step of coating the resist again on the surface, and the second resist pattern through the mask on which the second mask pattern is formed. A second exposure step for exposing the resist coated in the strike coating step; a second resist removing step for removing an exposed portion of the resist after the second exposure step; and the resist is removed. The first layer exposed in the region is etched with the second etching solution to form the semi-transmissive pattern, and the resist remaining in the second resist removing step is removed. This is solved by performing the second resist stripping step.

Thus, according to the photomask manufacturing method of the present invention, the resist is exposed using the mask on which the first mask pattern is formed, the exposed portion of the resist is removed, and the first etching solution The second layer is etched with, and then the resist is exposed with a mask on which the second mask pattern is formed, the exposed portion of the resist is removed, and the first layer is etched with the second etching solution. By doing so, a plurality of pattern formation regions can be formed on the surface of the transparent substrate.
That is, by utilizing the difference in resistance between the first layer and the second layer with respect to the etchant, a fine pattern can be obtained with little modification or damage by the etchant used for etching other layers. It can be formed with high accuracy.

According to the photomask substrate of the present invention, since the second layer can be selectively etched with the first etching solution and the first layer with the second etching solution, the first layer and the second layer can be etched. These layers are hardly modified or damaged by each other's etching solution, and it is possible to manufacture a photomask on which a fine pattern is formed with high accuracy by wet etching, which has been difficult in the past.
In addition, according to the photomask of the present invention and the manufacturing method thereof, the second layer can be selectively etched with the first etching solution and the first layer with the second etching solution. The layer and the second layer are hardly modified or damaged by each other's etching solution. Therefore, a photomask having a fine pattern with high accuracy can be formed by wet etching, which has been difficult in the past. It becomes possible.
Therefore, according to the present invention, patterning can be performed by wet etching suitable for manufacturing a large-scale photomask and mass production of photomasks. This makes it possible to manufacture a photomask.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, the members, arrangement, procedures, and the like described below do not limit the present invention, and various modifications can be made according to the spirit of the present invention.
1 is a longitudinal sectional view of a photomask substrate according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a photomask according to an embodiment of the present invention, and FIG. 3 is a pattern of a photomask from the photomask substrate. FIG. 4 is an explanatory view showing a step of patterning a photomask, FIG. 5 is a longitudinal sectional view of a photomask substrate according to another embodiment of the present invention, and FIG. 6 is a light shielding pattern formation. An electron micrograph of the photomask taken after the cross-pattern formation, FIG. 7 is an optical micrograph taken of the cross-patterned plane, and FIG. 8 is a photomask vertical cross-section and plane after the semi-transmissive pattern is formed. It is the electron micrograph which carried out. In FIGS. 1 to 5, in order to facilitate understanding of the invention, the photomask substrate, the photomask, and the photomask manufacturing process are schematically illustrated by drawing the thickness of each layer thicker than the actual thickness. Represents.

  As shown in FIG. 1, a photomask substrate (also referred to as a photomask blank) 2 in this example includes a transparent substrate 10, a semi-transmissive layer 20 formed on the surface of the transparent substrate 10, and a semi-transmissive layer 20. And a light shielding layer 33 formed on the surface of the substrate. Further, an antireflection layer 35 is formed on the surface of the light shielding layer 33. The photomask substrate 2 is a base substrate for manufacturing the photomask 1, and in the etching process and the photolithography process described later, the photomask substrate 2 is sequentially etched and patterned using different etching solutions. By doing so, the photomask 1 can be manufactured. The semi-transmissive layer 20 corresponds to the first layer of the present invention, and the composite layer 30 including the light shielding layer 33 and the antireflection layer 35 corresponds to the second layer of the present invention.

As shown in FIG. 2, the photomask 1 of this example includes a transparent substrate 10, a semi-transmissive pattern 20a formed on the surface of the transparent substrate 10, and a light shielding layer pattern 33a formed on the surface of the semi-transmissive pattern 20a. The antireflection layer pattern 35a is formed on the surface of the light shielding layer pattern 33a. The semi-transmissive pattern 20a is a pattern formed by etching the semi-transmissive layer 20 of the photomask substrate 2, the light shielding layer pattern 33a is a pattern formed by etching the light shielding layer 33, and the antireflection layer pattern 35a is an antireflection layer. This is a pattern formed by etching 35. The light shielding pattern 30a of the present invention is formed by the light shielding layer pattern 33a and the antireflection layer pattern 35a.
The photomask 1 includes a light-shielding portion 1a in which a part of the antireflection layer pattern 35a (that is, the light-shielding pattern 30a) is exposed on the surface and a half in which a part of the semi-transmissive pattern 20a is exposed on the surface when viewed from above. A transparent portion 1b is formed in which the transparent portion 1b and a part of the transparent substrate 10 are exposed on the surface.

(Transparent substrate 10)
Below, each member which comprises the board | substrate 2 for photomasks is demonstrated.
The transparent substrate 10 is a transparent substrate serving as a base for forming a photomask pattern. In the present embodiment, the transparent substrate 10 is a sufficiently polished quartz substrate. As the transparent substrate 10, materials such as natural quartz glass, synthetic quartz glass, and transparent resin film can be used. The term “transparent” as used herein specifically means that the transmittance (air reference) in the wavelength region of 350 to 500 nm is included in the range of 80 to 95%.

(Semi-transmissive layer 20)
A semi-transmissive layer 20 is formed on the surface of the transparent substrate 10. The semi-transmissive layer 20 of the present embodiment is a layer having a phase shift function that has a transmittance within a range of 5 to 70% in a wavelength region of a wavelength of 350 to 500 nm, and is titanium nitride (titanium nitride ( TiN _x : Here, it is formed of a material whose main component is 0 <x <1.33).
A film having such optical characteristics can be obtained by making the dielectric material into a multi-layer thin film based on wave optics theory. However, in consideration of patterning properties, selectivity to an etching solution and adhesion to a resist material From the viewpoint of tact time, pattern accuracy, etc., it is not necessarily preferable. Therefore, the semi-transmissive layer 20 is preferably formed as a single layer if possible without a laminated structure. It is also necessary to ensure optical characteristics with a material that can be easily patterned. Furthermore, from the viewpoint of photolithography, it is necessary to keep the reflectivity as low as possible. From this point of view, a thin film having moderate light absorption is more convenient.

  Examples of substances having such characteristics include metal oxides, nitrides, and oxynitrides. Further, also in the light shielding layer 33 described later, metal oxide, nitride, oxynitride and the like can be cited as constituent materials. Of the materials constituting the semi-transmissive layer 20 and the light-shielding layer 33, the basic elements may be the same or different, but materials that can be used in conventional photomask manufacturing processes and manufacturing facilities are appropriately selected. Select and use.

The semi-transmissive layer 20 and the light shielding layer 33 of the present invention are characterized in that they are resistant (insoluble or hardly soluble) to different etching solutions and are soluble.
That is, the semi-transmissive layer 20 is insoluble or hardly soluble in the etching solution A (first etching solution) and more easily soluble in the etching solution B (second etching solution) than the light shielding layer 33. is there. On the other hand, the light shielding layer 33 is more soluble in the etching solution A than the semi-transmissive layer 20 and is insoluble or hardly soluble in the etching solution B. In this embodiment, specifically, a mixed liquid of cerium ammonium nitrate, perchloric acid and water is used as the etching liquid A, and a mixed liquid of potassium hydroxide, hydrogen peroxide and water is used as the etching liquid B. Yes.

  As described above, the semi-transmissive layer 20 and the light-shielding layer 33 are different from each other in insolubility or poor solubility in the etching liquid A and easily soluble in the etching liquid B. The light shielding layer 33 can be selectively etched with the etching solution A.

In this case, the semi-transmissive layer 20 being insoluble or hardly soluble in the etching solution A than the light-shielding layer 33 means that the solubility of the semi-transmissive layer 20 in the etching solution A is substantially zero or the light shielding. It means that it is extremely lower than the solubility of the layer 33.
Conversely, the semi-transmissive layer 20 being more soluble in the etching solution B than the light shielding layer 33 means that the solubility of the semi-transmissive layer 20 in the etching solution B is extremely higher than that of the light shielding layer 33. To do.
Further, even when the light shielding layer 33 is insoluble or hardly soluble in the etching solution B than the semi-transmissive layer 20, the solubility of the light shielding layer 33 in the etching solution B is substantially zero or the semi-transmissive layer 20. It is extremely lower than the solubility of.
On the contrary, that the light shielding layer 33 is more soluble in the etching solution A than the semi-transmissive layer 20 means that the solubility of the light shielding layer 33 in the etching solution A is extremely higher than that of the semi-transmissive layer 20. To do.

Specifically, in this embodiment, the transmissivity at 436 nm of the semi-transmissive layer 20 when immersed in the etching solution A at 30 ° C. for about 70 seconds (that is, the time during which the light shielding layer 33 can be completely etched) is the etching solution. The transmittance before immersion in A is ± 0.5% or less. This indicates that the semi-transmissive layer 20 is hardly changed (not etched) by the etching solution A even under the condition that the light shielding layer 33 can be completely etched by the etching solution A.
Further, the optical density of the light shielding layer 33 when immersed in the etching solution B at 30 ° C. for 120 seconds (that is, the time during which the semi-transmissive layer 20 can be completely etched) is −0.3 or less. This indicates that the light-shielding layer 33 is hardly changed by the etching solution B (not etched) even under the condition that the semi-transmissive layer 20 can be completely etched by the etching solution B.
Thus, since the solubility with respect to the etching liquid of the semi-transmissive layer 20 and the light shielding layer 33 differs, it becomes possible to selectively etch the semi-transmissive layer 20 and the light shielding layer 33 using the solubility characteristic.

The inventors of the present invention have used an etching solution A (a mixed solution of cerium ammonium nitrate, perchloric acid and water) and an etching solution B (potassium hydroxide, hydrogen peroxide) for some metal oxides, nitrides, and oxynitrides. And water solubility). The metals used are nickel, titanium, tantalum, aluminum, molybdenum and copper.
As a result, for nickel, molybdenum, and copper, any of oxide, nitride, and oxynitride was soluble in the etching solution A and insoluble in the etching solution B. For this reason, it turned out that it is unsuitable for using for the selective etching with the light shielding layer 33.
Further, when the oxides, nitrides, and oxynitrides of aluminum, tantalum, and titanium were examined, all of them were insoluble in the etching solution A, but the titanium nitride and titanium were insoluble in the etching solution B. This oxynitride was found to be soluble.

  Furthermore, pattern formation by etching was performed on these compounds, and the pattern accuracy was individually examined. As a result, it was found that tantalum oxide, nitride, oxynitride, aluminum oxide, and titanium oxide are not suitable for wet etching because pattern formation is impossible or pattern accuracy is low. .

From this investigation result, the selection of the etching solution and the feasibility of patterning were examined for a titanium nitride (TiN _x ) film having etching resistance and optical characteristics against the etching solution A. First, as a result of repeated investigations on the solubility and etchability for various chemicals, this titanium nitride (TiN _x ) film has alkali (eg, potassium hydroxide (KOH)) resistance in the photolithography process, It was found that it is soluble in a mixed solution of hydrogen peroxide (H ₂ O ₂ ), potassium hydroxide (KOH), and water, and a fine pattern is possible. That is, titanium nitride (TiN _x ) has resistance to the etching solution A that solubilizes the light-shielding layer 33 in addition to the properties that can achieve desired optical properties, and alkali contained in the resist removal solution. It was found to be resistant to. For this reason, it was found that by selecting titanium nitride (TiN _x ) as the material of the semi-transmissive layer 20, the film itself has good etching characteristics in terms of selectivity with the light shielding layer 33.

  Next, the adhesion of the semi-transmissive layer 20 to the transparent substrate 10 and the adhesion to the light shielding layer 33 were examined. The semi-transmissive layer 20 needs to be etched without causing a step or an overhang between the light-shielding layer 33 in the patterning process while ensuring adhesion to the transparent substrate 10. The semi-transmissive layer 20 is required to be a layer having both of these optical characteristics and the above-described chemical resistance (etching solution resistance, alkali resistance, etc.).

A test was performed on the adhesion of the semi-transmissive layer 20, and the adhesion of the semi-transmissive layer 20 to the transparent substrate 10 was evaluated. Specifically, a titanium nitride (TiN _x ) film is formed on the surface of the transparent substrate 10, a plurality of cells are formed by cutting with a cutter in a lattice shape at intervals of 1 mm, and an adhesive tape is attached thereto. A peel test was performed. As a result, it was found that no peeling occurred in all the cells and the adhesion to the transparent substrate 10 was good. From this, it can be said that the titanium nitride (TiN _x ) film has high adhesion to the transparent substrate 10 and is suitable as a material for the semi-transmissive layer 20. Further, even if the film is formed directly on the transparent substrate 10, the adhesiveness with the transparent substrate 10 is good, so that even on the surface of the transparent substrate 10 without using a layer for improving the adhesiveness such as a metal compound layer. Direct film formation is possible.

As described above, titanium nitride (TiN _x ) has optical properties, resistance to the etching solution A (insoluble or hardly soluble), and solubility (easily soluble) to the etching solution B, and also has good adhesion to the transparent substrate 10. Therefore, it can be said that it is the most preferable material for the semi-transmissive layer 20.

(Light shielding layer 33)
Next, the light shielding layer 33 will be described. The light shielding layer 33 is a layer formed on the surface of the semi-transmissive layer 20 and has a property of shielding almost 100% of irradiation light. In this embodiment, metal chromium (Cr) is formed to have a transmittance of 0.1% or less (optical density of 3.0 or more). As the material of the light shielding layer 33, in addition to chromium, metals such as titanium, molybdenum, aluminum, nickel, copper, oxides, nitrides, oxynitrides of these metals, and further these metals and metal compounds are used. Examples of the alloy include two or more types.

  The light shielding layer 33 is more soluble in the etching solution A than the semi-transmissive layer 20 and insoluble or hardly soluble in the etching solution B. Therefore, by using the etching solution A, it is possible to selectively etch only the light shielding layer 33 without etching the semi-transmissive layer 20.

(Antireflection layer 35)
Next, the antireflection layer 35 will be described. The antireflection layer 35 is formed on the surface of the light shielding layer 33 and is a layer for reducing the reflectance. In this embodiment, chromium oxide (CrO _x ), which is a chromium oxide, is used as a main component as the material of the antireflection layer 35, but the material of the antireflection layer 35 is not limited to this.

  In the present invention, the antireflection layer 35 has an arbitrary configuration, and the antireflection layer 35 is not necessarily provided. However, when a fine pattern such as LSI is formed using the photomask 1 obtained by patterning the photomask substrate 2, the reflection of the reflected light is prevented by preventing the reflection of the irradiation light by the antireflection layer 35. Moire and halation due to interference can be reduced.

The antireflection layer 35 is a thin film that obtains an antireflection effect by utilizing wave interference in terms of wave optics. The material forming the antireflection layer 35 is a refractive index (n) and absorption (k) with respect to irradiation light (where refractive index and absorption are the speed of light in vacuum and the phase in the material (in the thin film)). The complex refractive index, which is the ratio of speeds, generally has the characteristics shown in Table 1 below, depending on the combination of the refractive index (n) and the absorption coefficient (k) represented by N = n-ik. .
The left column (refractive index) of this table shows the relative refractive index with respect to the irradiation light of the antireflection layer 35 as compared with the light shielding layer 33 (any one of “low”, “same”, “high”). It shows. In the middle column (absorption), the absorption (in a range smaller than the absorption of the light shielding layer 33) with respect to the irradiation light of the antireflection layer 35 is set to any of relative (“low”, “medium”, and “high”). ?)
The right column (Reflectance) indicates the relative characteristics of the reflectance. “↓” indicates that the reflectance is low, “→” indicates that the reflectance is intermediate, and “↑” indicates that the reflectance is high. Is shown. Furthermore, in this column, evaluations according to the height of the antireflection effect are indicated by symbols “x”, “Δ”, and “◯” in descending order of effectiveness.

From this table, the following can be said.
A substance that absorbs less irradiation light than the light shielding layer 33 and absorbs less in the antireflection layer 35 (for example, the value of k is 0.2 to 0.5) has a low reflectance and is reflected High prevention effect.
A substance that absorbs less light than the light shielding layer 33 and has a moderate absorption among the antireflection layers 35 (for example, a k value of 0.5 to 1.0) has a medium reflectance. Therefore, the antireflection effect is moderate.
On the other hand, a substance that satisfies the following requirements has a low antireflection effect or almost no antireflection effect.
A substance that absorbs less irradiation light than the light shielding layer 33 and absorbs much in the antireflection layer 35 (for example, the value of k is 1.0 to 2.0) has a high reflectance, and thus reflects. The prevention effect is low.
As described above, the antireflection layer 35 is a substance that absorbs less light than the light shielding layer 33 with respect to the wavelength used, and has an optical film thickness nd = p × λ / 4 (where λ is the design wavelength, p is 1, n is a refractive index, and d is a substantial film thickness).
Actually, since each of the light shielding layer 33 and the antireflection layer 35 has wavelength dispersion of the refractive index, p is formed in the range of 0.5 to less than 1.0.
Further, when the absorption of the antireflection layer 35 is further reduced (for example, the value of k is 0.01 to 0.1), for example, the reflectance increases in comparison with when k = 0.2 to 0.5. Accordingly, the antireflection effect is reduced, so that an appropriate adjustment is required according to the optical characteristics of the light shielding layer 33.

  The antireflection layer 35 has the same etching characteristics as the light shielding layer 33. That is, the antireflection layer 35 is more soluble in the etching solution A than the semi-transmissive layer 20 and is insoluble or hardly soluble in the etching solution B. For this reason, by using the etching solution A, it is possible to etch only the antireflection layer 35 without etching the semi-transmissive layer 20. Further, since the antireflection layer 35 and the light shielding layer 33 are laminated, the antireflection layer 35 and the light shielding layer 33 can be etched together by using the etching solution A.

  The material of the antireflection layer 35 is preferably made of the same material as the light shielding layer 33 in consideration of the etching characteristics and the convenience of film formation described above, but is easily soluble in the etching solution A. Further, other materials may be used as long as they are insoluble or hardly soluble in the etching solution B.

Next, the manufacturing method of the photomask 1 of this invention is demonstrated.
The photomask 1 of the present invention uses a photomask substrate 2 in which a transflective layer 20, a light shielding layer 33, and an antireflection layer 35 are sequentially stacked on the surface of a transparent substrate 10, and wet etching is performed on each layer. It is manufactured by forming a predetermined pattern. Examples of the film forming method include physical vapor deposition (PVD) using vacuum such as sputtering, vapor deposition, and ion plating, and vapor deposition (CVD) such as plasma CVD and thermal CVD.

When forming a film by sputtering, reactive sputtering can be used in addition to normal sputtering. One reactive sputtering apparatus is an apparatus including a film formation region for sputtering a target and a reaction region for plasma processing a thin film after film formation using plasma of a reactive gas. The second is an ordinary sputtering apparatus in which a reactive gas is introduced during film formation and the reaction is promoted by utilizing plasma by sputtering. Thereafter, the second reactive sputtering apparatus is used to form a film. Titanium nitride (TiN _x ) is used as the semi-transmissive layer 20, metallic chromium (Cr) is used as the light shielding layer 33, and chromium oxide (CrO _x ) is used as the antireflection layer 35. An example of forming a thin film will be described.

(Film formation process)
First, the semi-transmissive layer 20 is formed. In forming the semi-transmissive layer 20, titanium metal is used as a target. Before starting the film formation, the transparent substrate 10 is set on the substrate holder of the sputtering apparatus. Titanium (Ti) jumping out of the target is reactive by applying a voltage to the sputtering electrode by introducing an inert gas (Ar) and a reactive gas (N ₂ ) into the target and applying a voltage to the target. By reacting with gas (N ₂ ) in plasma, a thin film of titanium nitride (TiN _x ) is formed on the surface of the transparent substrate 10. Thereby, the semi-transmissive layer 20 is formed on the surface of the transparent substrate 10 (semi-transmissive layer film forming step).

  Next, the light shielding layer 33 is formed. Prior to the formation of the light shielding layer 33, the target is exchanged from metallic titanium to metallic chromium (Cr). In this state, the inside of the sputtering apparatus is again brought into a high vacuum state, and the target is sputtered to form the light shielding layer 33 made of metallic chromium (Cr) on the surface of the semi-transmissive layer 20 (light shielding layer forming step).

  Subsequently, the antireflection layer 35 is formed. Since the antireflection layer 35 contains chromium as a main component like the light shielding layer 33, the film formation can be performed subsequent to the film formation of the light shielding layer 33 without changing the target.

Metal chromium is used as a target in the same way as when titanium nitride is deposited. After the light shielding layer 33 is formed, the inert gas (Ar) and the reactive gas (O ₂ ) are introduced into the target and a voltage is applied to the sputter electrode, so that chromium (Cr) jumping out of the target is reacted with the reactive gas. By reacting with (O ₂ ) in plasma, a thin film of chromium oxide (CrO _x ) is formed on the surface of the light shielding layer 33. Thereby, the antireflection layer 35 is formed on the surface of the light shielding layer 33 (antireflection layer forming step).
When the antireflection layer 35 is made of a metal material different from that of the light shielding layer 33, the antireflection layer 35 is formed by replacing the target after the light shielding layer 33 is formed.
Next, the photomask substrate 2 after film formation is cleaned by ultrasonic cleaning or the like to remove foreign matter on the surface.

(Patterning process)
A predetermined pattern is formed on the photomask substrate 2 having the laminated structure formed as described above by using a photolithography technique and an etching technique. This pattern formation process (patterning process) will be described with reference to FIGS.

  First, a photomask substrate 2 before patterning is prepared (FIG. 3A). The photomask substrate 2 can be manufactured by using the film formation technique such as sputtering described above. Next, a resist 50 is applied to the surface of the photomask substrate 2 by using a method such as spin coating (FIG. 3B). The resist 50 is a photosensitive polymer material that is cured by ultraviolet rays or the like. The resist coating method is not limited to spin coating, and known methods such as spray coating and roll coating can be used. Next, the applied resist 50 is preheated (temporarily cured) with a heater or the like at a high temperature. Thus, the resist 50 is coated on the surface of the photomask substrate 2 (first resist coating step).

  Next, a mask pattern is formed on the resist 50 using the mask original plate 60. The mask original 60 is a member in which a predetermined pattern (first mask pattern) is written in advance, and the pattern is transferred to the resist 50. The resist 50 is exposed to ultraviolet rays through the mask original plate 60 to be exposed (FIG. 3C). Thereby, the surface of the resist 50 is exposed according to the first mask pattern (first exposure step).

  Subsequently, the exposed resist 50 is immersed in a developer. As a result, the region exposed to ultraviolet rays in the resist 50 is removed by the developer, and the antireflection layer 35 under the region is exposed on the surface (FIG. 3D). After the resist 50 is partially removed, the remaining resist 50 is post-baked (mainly cured) at a high temperature using a heater or the like. Thereby, a part of the resist 50 is removed, and the same pattern as the first mask pattern is formed with the remaining resist 50 (first resist removing step).

  Next, the antireflection layer 35 and the light shielding layer 33 are etched using the etching solution A (that is, the first etching solution). Etching solution A is a mixed solution of cerium ammonium nitrate, perchloric acid, and water. The bath is filled with the etching solution A, and the antireflection layer 35 exposed after removing the resist is completely immersed in the etching solution A. In this state, the etching is advanced while maintaining a predetermined etching temperature. Since both the antireflection layer 35 and the light shielding layer 33 are easily soluble in the etching solution A, the same pattern as the remaining pattern of the resist 50 is formed by etching together with the etching solution A.

  On the other hand, since the semi-transmissive layer 20 is insoluble or hardly soluble in the etching solution A, it has a role as an etching stop layer. For this reason, even if the light shielding layer 33 is etched by the etching solution A, the semi-transmissive layer 20 remains as it is without being etched by the etching solution A (FIG. 3E). Thereby, the light shielding pattern 30a composed of the light shielding layer pattern 33a and the antireflection layer pattern 35a is formed on the surface of the semi-transmissive layer 20 (first etching step).

  Subsequently, the resist 50 remaining on the surface is dissolved with a release agent, and the surface is washed with pure water or the like (FIG. 3F). Thereby, the same pattern as the first mask pattern is left on the surface of the transparent substrate 10 (first resist stripping step).

  Next, a resist 70 is applied to the surface and temporarily cured (FIG. 4B). The resist 70 may be made of the same material as that of the previous resist 50 or may be made of a material having a different curing performance. Thus, the surface is coated with the resist 70 (second resist coating step).

  Subsequently, a mask pattern is formed on the resist 70 using the mask original plate 80. The mask original plate 80 is a member in which a predetermined pattern (second mask pattern) is written in advance as in the mask original plate 60. The resist 70 is exposed to ultraviolet rays through the mask original plate 80 to be exposed (FIG. 4C). Thereby, the surface of the resist 70 is exposed in accordance with the second mask pattern (second exposure step).

  Next, the exposed resist 70 is immersed in a developing solution, and the region exposed to ultraviolet rays in the resist 70 is removed (FIG. 4D). Thereby, a part of the resist 70 is removed, and the same pattern as the second mask pattern is formed by the remaining resist 70 (second resist removing step).

  Subsequently, the semi-transmissive layer 20 is etched using the etching solution B (that is, the second etching solution). The etching solution B is a mixed solution of potassium hydroxide, hydrogen peroxide, and water. The bath is filled with the etching solution B, and the semi-transmissive layer 20 exposed after removing the resist is completely immersed in the etching solution B. In this state, the etching is advanced while maintaining a predetermined etching temperature. Since the semi-transmissive layer 20 is easily soluble in the etching solution B, a pattern corresponding to the remaining pattern of the resist 70 is formed by etching with the etching solution B.

  On the other hand, since both the light shielding layer 33 and the antireflection layer 35 are insoluble or hardly soluble in the etching solution B, the light shielding pattern 30a formed from these layers is not etched by the etching solution B (FIG. 4E). ). Thereby, the semi-transmissive pattern 20a is formed on the surface of the transparent substrate 10 (second etching step).

  Finally, the resist 70 remaining on the surface is dissolved with a release agent, and the surface is washed with pure water or the like (FIG. 4F). Thereby, the same pattern as the second mask pattern remains on the surface of the transparent substrate 10 (second resist stripping step).

  When etching is performed by this method, as shown in FIG. 2, the non-transmissive layer 20, the light shielding layer 33, and the antireflection layer 35 are not etched in the portion not exposed by the first mask pattern, and the antireflection layer 35 (reflection) When the prevention layer 35 is not provided, a region (the light shielding portion 1a) where the light shielding layer 33) is exposed on the surface is formed. Further, in the portion exposed with the first mask pattern but not exposed with the second mask pattern, only the light shielding layer 33 and the antireflection layer 35 are etched and the semi-transmissive layer 20 is exposed on the surface (semi-transmissive portion 1b). It is formed. Further, in the portion exposed by both the first mask pattern and the second mask pattern, the transparent substrate 10 is exposed on the surface by etching all of the semi-transmissive layer 20, the light shielding layer 33, and the antireflection layer 35. (Transparent part 1c) is formed.

  The photomask 1 manufactured in this way can be used as a multi-tone mask used when manufacturing a TFT panel or the like. In a manufacturing process of a TFT panel or the like, a transfer substrate is placed so as to face the surface side (antireflection layer 35 side) of the multi-tone mask, and transfer light is irradiated from the transparent substrate 10 side toward the transfer substrate. When light is irradiated from the transparent substrate 10 side toward the antireflection layer 35 side, the irradiation light is blocked by the light shielding portion 1a, and an intermediate amount of light (transmittance of 5 to 70%) is transmitted through the semi-transmissive portion 1b. The part 1c transmits light with a transmittance of almost 100%. For this reason, on the opposite transfer substrate, transfer is performed at three different exposure levels: an unexposed portion by the light shielding portion 1a, a semi-exposed portion by the semi-transmissive portion 1b, and a completely exposed portion by the transparent portion 1c.

  Thus, by using the photomask 1 of the present invention as a pattern transfer mask in the photolithography technique, a plurality of transfer patterns having different exposure intensities can be easily formed. Moreover, the variation of exposure can further be increased by changing the wavelength and intensity of the irradiated light.

  Note that the translucent layer 20 of the present embodiment is directly coated on the transparent substrate 10. For this reason, it is not necessary to previously form a special layer for increasing the adhesion of the semi-transmissive layer 20 on the surface of the transparent substrate 10, and the film forming process can be shortened. In addition, the semi-transmissive layer 20 has an effect of reducing the reflectance from the glass surface side of the light shielding layer 33 at the time of exposure. As a result, it is possible to reduce halation with respect to the irradiation light and to reduce the moire phenomenon in a continuous fine stripe pattern portion and improve the pattern accuracy.

  On the other hand, as shown in FIG. 5, a metal compound layer 90 that improves the adhesion with the semi-transmissive layer 20 may be formed on the surface of the transparent substrate 10. In this case, the metal compound layer 90 preferably has a transmittance of irradiation light of 70% or more and less than 100%.

Such a metal compound layer 90 is formed of a substance that protects the surface of the transparent substrate 10 from the etching solution and has high adhesion to the semi-transmissive layer 20. Examples of such materials include silicon oxide, aluminum oxide, titanium oxide, and other metal oxides.
The metal compound layer 90 is formed on the surface of the transparent substrate 10 using a known film formation technique such as sputtering before forming the semi-transmissive layer 20.

In the description of the above embodiment, the etching solution A (a mixed solution of cerium ammonium nitrate, perchloric acid and water) that is a first etching solution, and the etching solution B (potassium hydroxide, a second etching solution). A mixed solution of hydrogen peroxide and water), a semi-transparent first layer (a layer containing titanium nitride as a main component), a second layer (chromium layer) that substantially blocks irradiation light, and antireflection The case of the layer (chromium oxide layer) has been described, but the first layer material and the second layer material are replaced, and the first etching solution and the second etching solution are replaced. The same effect and action can be obtained for.
That is, the first layer is a layer mainly composed of one or more components selected from the group consisting of chromium, chromium oxide, chromium nitride and chromic oxynitride, and the second layer is The layer is composed mainly of one or more components selected from the group consisting of titanium, titanium nitride, and titanium oxynitride. Then, a mixed solution of potassium hydroxide, hydrogen peroxide and water is used as the first etching solution, and a mixed solution of cerium ammonium nitrate, perchloric acid and water is used as the second etching solution. Even in this case, the same operation and effect as the above-described embodiment can be obtained.

Hereinafter, a photomask substrate 2 of the present invention and a method of manufacturing the photomask 1 using the photomask substrate 2 will be described with specific examples.
(Example 1)
In this embodiment, each layer on the surface of the transparent substrate 10 is manufactured by a film forming method using vacuum. Specifically, a reactive sputtering apparatus (1900 manufactured by SYNCHRON Co., Ltd.) using a reactive gas such as nitrogen gas or oxygen gas was used.

In this example, the quartz substrate (transparent substrate 10) was first set in a sputtering apparatus, and reactive sputtering was performed using a commercially available metal titanium target (purity 99.99% or more). In the sputtering step, the semi-transparent layer 20 was formed by nitriding titanium by sputtering while introducing nitrogen gas to form a thin film of titanium nitride (TiNx: 0 <x <1.33). . At this time, the semi-transmissive layer 20 was formed so as to have a transmittance of 15% at a wavelength of 436 nm.
The target at this time is not limited to the one using the metal titanium target as in this example, and may be one obtained by bonding a sintered body of titanium nitride. In addition, since the degree of nitridation varies depending on the apparatus, it may be adjusted by appropriately combining film forming conditions.

  Next, the metal titanium target was changed to a metal chrome target, and the light shielding layer 33 was formed on the surface of the semi-transmissive layer 20 so that the film thickness was 700 mm (70.0 nm). At this time, no reactive gas was introduced, and only metallic chromium (Cr) was formed on the surface of the semi-transmissive layer 20. The light shielding layer 33 that functions as a light shielding layer is preferably sputtered at high speed under high vacuum as much as possible in order to obtain an optical property having an optical density (OD) of 3.0 or more. However, if the film thickness increases rapidly by sputtering at a high speed, the stress of the chromium film forming the light shielding layer 33 increases. Therefore, it is preferable to perform high vacuum and high speed sputtering in an appropriate range.

Subsequently, the target was changed to another new metal chromium target, and the antireflection layer 35 was formed to a film thickness of 300 mm (30.0 nm). In the sputtering step, metal chromium was converted to chromium oxide (CrO _x : 0 <x <1.5) by sputtering while introducing oxygen gas. The reflectance of chromium, which is a light shielding layer, is usually around 60%, and in order to reduce this reflectance, the film is formed with an appropriate refractive index and absorption according to the apparatus.
The general reflectance at this time is 25 to 30% at a wavelength of 650 nm and at least 6 to 8% near 430 nm when the antireflection layer 35 is formed. It is possible to suppress the reflectance to an average of several percent by laminating two to three antireflection layers 35.

  Next, the photomask substrate 2 formed in the sputtering step was taken out of the sputtering apparatus and left in a storage for one week. Subsequently, the photomask substrate 2 taken out from the storage is subjected to ultrasonic cleaning in each of a plurality of baths of alkaline detergent, neutral detergent, and pure water, and then the entire surface of the photomask substrate 2. A resist (AZ RFP-230K2 manufactured by AZ Electronic Materials Co., Ltd.) was applied to the film and temporarily cured. In this resist coating process, the surface of the photomask substrate 2 is not surface-treated with chemicals, plasma, ultraviolet rays or the like. Hereinafter, the same applies to similar processing.

  After preliminary curing of the resist, exposure of the second stripe pattern (Oak Manufacturing Jet Printer: light source CHM-2000, exposure for 16 seconds with an ultra-high pressure mercury lamp), development (Tokyo Ohka Co., Ltd. PMER developer: temperature 30 ° C., 1 Minute) and main curing (DX402 dry oven manufactured by Yamato Kagaku: 120 ° C., 10 minutes). Two kinds of stripe patterns having a line width of 5 μm and 2 μm were used. Subsequently, a mixed solution of perchloric acid, cerium ammonium nitrate and water (perchloric acid: cerium ammonium nitrate: water = 4: 17: 70, reaction temperature: 30 ° C., etching time: 100 seconds, which is the first etching solution. The light shielding layer 33 and the antireflection layer 35 are etched simultaneously to form a stripe pattern composed of the light shielding pattern 30a in which the light shielding layer pattern 33a and the antireflection layer pattern 35a are stacked. Next, the resist was removed with a predetermined chemical solution or the like.

  Since the overetch dimension of the light shielding pattern 30a including the light shielding layer pattern 33a and the antireflection layer pattern 35a at this time was not measurable with an optical microscope, the photomask substrate 2 after pattern formation (after resist removal) ( Hereinafter, the substrate was simply cut in the vertical direction, and the cross section and plane were observed with an electron microscope. The photographed electron micrographs are shown in FIGS. 6A is a cross-sectional photograph showing the cross-sectional shape of the linear pattern, and is an electron micrograph taken before the resist is removed. FIG. 6B is a cross-sectional photograph showing the cross-sectional shape of the linear pattern. The electron micrograph which image | photographed the state after removal, (c) is the front photo which expanded and image | photographed the edge part of a linear pattern, Comprising: The electron micrograph which image | photographed the state after photoresist removal.

Among these, it can be seen from the results of cross-sectional observations (a) and (b) that the semi-transmissive layer 20 and the light-shielding pattern 30a are laminated on the surface of the transparent substrate 10. In addition, the cross-sectional observation result of (a) shows that the light shielding pattern 30a is over-etched from the end of the resist toward the inside. The overetch dimension was found to be 0.38 μm from the photograph (a). Further, from the result of the front observation of (c), it was found that irregularities occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that no particular change was observed in the titanium nitride (TiN _x ) film as the semi-transmissive layer 20 and the film remained on the surface of the transparent substrate 10.

  Next, the substrate after removing the resist was rotated 90 degrees, and the resist was again applied to the entire surface and temporarily cured. Then, exposure of the first stripe pattern (Oak Manufacturing Jet Printer: light source CHM-2000, exposure for 16 seconds with an ultra-high pressure mercury lamp), development (Tokyo Ohka Co., Ltd. PMER developer: temperature 30 ° C., 1 minute), Full curing (DX402 dry oven manufactured by Yamato Scientific: 120 ° C., 10 minutes) was performed. Subsequently, a mixed solution of hydrogen peroxide, potassium hydroxide, and water (hydrogen peroxide (35% aqueous solution): potassium hydroxide (30% aqueous solution): water = 16: 1: 32) as a second etching solution The stripe pattern composed of the semi-transmissive pattern 20a was formed by etching the semi-transmissive layer 20 by immersing in a temperature of 30 ° C. and an etching time of 150 seconds. As a result, a pattern was obtained in which the light-shielding portion 1a in which the semi-transmissive pattern 20a and the light-shielding pattern 30a were laminated and the semi-transmissive portion 1b composed only of the semi-transmissive pattern 20a crossed on the surface of one transparent substrate 10 ( (See FIG. 7).

The left photograph of FIG. 7 shows an example in which patterning is performed so that the line width of the pattern becomes 5 μm, and the right photograph shows an example in which patterning is performed so that the line width becomes 2 μm. The straight line pattern (vertical straight line) on the near side of each photograph is the light shielding pattern 30a, and the linear pattern (horizontal straight line) formed under the light shielding pattern 30a is the semi-transmissive pattern 20a. A grid-like region located under the semi-transmissive pattern 20 a is the upper surface of the transparent substrate 10.
From the photograph of FIG. 7, it can be seen that each pattern has good linearity even when the line width is as short as 2 μm. For this reason, according to the manufacturing method of the photomask of this invention, it turned out that a fine pattern can be formed with high precision.

  Next, similarly to the case where the overetch dimension was measured after the formation of the light shielding pattern 30a, the substrate was cut in the vertical direction, and the cross section and the plane were observed with an electron microscope. The photographed electron micrographs are shown in FIGS. FIG. 8A is a cross-sectional photograph showing the cross-sectional shape of the linear pattern, and is an electron micrograph taken before removing the resist, and FIG. 8B is a cross-sectional photo showing the cross-sectional shape of the linear pattern. The electron micrograph which image | photographed the state after removal, (c) is the front photo which expanded and image | photographed the edge part of a linear pattern, Comprising: The electron micrograph which image | photographed the state after photoresist removal.

  Among these, it can be seen from the results of cross-sectional observations in FIGS. 8A and 8B that the semi-transmissive pattern 20a is formed on the surface of the transparent substrate 10. FIG. Further, from the cross-sectional observation result of (a), it can be seen that the semi-transmissive pattern 20a is over-etched from the end of the resist toward the inside. This overetched dimension was found to be 0.37 μm from the photograph (a). Moreover, from the result of the front observation of (c), it was found that the unevenness dimension of the edge portion was relatively small as 0.05 μm or less with respect to the linear pattern, and the linearity was sufficiently maintained. For this reason, the linearity of the pattern is not considered a problem level.

  Using another substrate that is not patterned, the optical density (OD) is measured with a Macbeth densitometer manufactured by Konishi Roku Photo Industry Co., Ltd., and an etching solution A comprising a mixture of perchloric acid, cerium ammonium nitrate, and water is used. The light shielding layer 33 and the antireflection layer 35 were etched and then washed well, and the spectral transmittance, which is an optical characteristic manufactured by Hitachi High-Technologies, was measured with a self-recording spectrophotometer U-4000. The resulting optical density was 3.38, and the transmittance was 6.91% at 350 nm, 14.73% at 436 nm, and 18.29% at 500 nm.

Using a part of the cross pattern, the semi-transmissive pattern 20a and the light shielding pattern 30a were measured by a stylus type surface shape measuring device Decak made by ULVAC. As a result, the film thickness of the semi-transmissive pattern 20a was 319 mm (31.9 nm), and the film thickness of the light shielding pattern 30a was 1020 mm (102.0 nm). Since the thickness setting of the light shielding layer pattern 33a is 700 mm and the antireflection layer pattern 35a is 300 mm (30.0 nm), 1020 mm (102.0 nm) of the thickness of the light shielding pattern 30a is an error range of the measuring instrument. It was confirmed that the target value was almost the same. The results are shown in Table 2.

(Example 2)
In the second embodiment, unlike the first embodiment, the transflective layer 20 is designed so that the transmittance at 436 nm is 20%. In this example, it is designed such that the transmittance of the irradiated light at 436 nm is about 20% by adjusting the film thickness of the semi-transmissive layer 20. Other conditions are the same as in the first embodiment.

In the same procedure as in Example 1, the light shielding layer 33 and the antireflection layer 35 were etched to form a stripe pattern composed of the light shielding pattern 30a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 6 of Example 1 was taken, and the cross section and plane were observed. As a result of cross-sectional observation, it was found that the overetch dimension was 0.37 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that no particular change was observed in the titanium nitride (TiN _x ) film as the semi-transmissive layer 20 and the film remained on the surface of the transparent substrate 10.

Next, the semi-transmissive layer 20 was etched in the same procedure as in Example 1 to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.39 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is 0.05 micrometer or less with respect to a linear pattern, and is small enough.
Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.29, the transmittance was 12.85% at 350 nm, 21.14% at 436 nm, and 25.53% at 500 nm.
Furthermore, as a result of measuring the film thickness, the film thickness of the semi-transmissive pattern 20a was 260 mm (26.0 nm), and the film thickness of the light shielding pattern 30a was 1015 mm (101.5 nm). These results are shown in Table 2.

(Example 3)
In the third embodiment, unlike the first and second embodiments, the transflective layer 20 is designed so that the transmittance at 436 nm is 30%. In this example, the transmittance of the irradiated light at 436 nm is designed to be about 30% by adjusting the film thickness of the semi-transmissive layer 20, but the other conditions are the same as in Examples 1 and 2. It is the same.

In the same procedure as in Example 1, the light shielding layer 33 and the antireflection layer 35 were etched to form a stripe pattern composed of the light shielding pattern 30a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that of FIG. From the result of cross-sectional observation, it was found that the overetch dimension was 0.39 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that no particular change was observed in the titanium nitride (TiN _x ) film that is the semi-transmissive layer 20 and it remained on the surface of the transparent substrate 10.

  Next, in the same procedure as in Example 1, the semi-transmissive layer 20 was etched to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.35 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is as small as 0.05 micrometer or less with respect to a linear pattern.

Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.22, the transmittance was 18.79% at 350 nm, 29.67% at 436 nm, and 32.78% at 500 nm.
Furthermore, as a result of film thickness measurement, the film thickness of the semi-transmissive pattern 20a was 231 mm (23.1 nm), and the film thickness of the light shielding pattern 30a was 1005 mm (100.5 nm). These results are shown in Table 2.

Example 4
In the fourth embodiment, unlike the first to third embodiments, the transflective layer 20 is designed so that the transmittance at 436 nm is 40%. In this example, it is designed so that the transmittance at 436 nm of the irradiated light is about 40% by adjusting the film thickness of the semi-transmissive layer 20, but other conditions are the same as in Examples 1 to 3. It is.

In the same procedure as in Example 1, the light shielding layer 33 and the antireflection layer 35 were etched to form a stripe pattern composed of the light shielding pattern 30a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 6 of Example 1 was taken, and the cross section and plane were observed. As a result of cross-sectional observation, it was found that the overetch dimension was 0.38 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that no particular change was observed in the titanium nitride (TiN _x ) film as the semi-transmissive layer 20 and the film remained on the surface of the transparent substrate 10.

  Next, in the same procedure as in Example 1, the semi-transmissive layer 20 was etched to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.38 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is as small as 0.05 micrometer or less with respect to a linear pattern.

Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.17, the transmittance was 28.05% at 350 nm, 39.93% at 436 nm, and 48.18% at 500 nm.
Furthermore, as a result of measuring the film thickness, the film thickness of the semi-transmissive pattern 20a was 209 mm (20.9 nm), and the film thickness of the light shielding pattern 30a was 1000 mm (100.0 nm). These results are shown in Table 2.

(Example 5)
In the fifth embodiment, unlike the first to fourth embodiments, the transflective layer 20 is designed so that the transmittance at 436 nm is 50%. In this example, it is designed so that the transmittance at 436 nm of irradiated light is about 50% by adjusting the film thickness of the semi-transmissive layer 20, but the other conditions are the same as in Examples 1 to 4. It is.

In the same procedure as in Example 1, the light shielding layer 33 and the antireflection layer 35 were etched to form a stripe pattern composed of the light shielding pattern 30a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 6 of Example 1 was taken, and the cross section and plane were observed. As a result of cross-sectional observation, it was found that the overetch dimension was 0.35 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that no particular change was observed in the titanium nitride (TiN _x ) film as the semi-transmissive layer 20 and the film remained on the surface of the transparent substrate 10.

  Next, in the same procedure as in Example 1, the semi-transmissive layer 20 was etched to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.40 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is as small as 0.05 micrometer or less with respect to a linear pattern.

Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.03, the transmittance was 40.01% at 350 nm, 52.03% at 436 nm, and 59.59% at 500 nm.
Furthermore, as a result of measuring the film thickness, the film thickness of the semi-transmissive pattern 20a was 153 mm (15.3 nm), and the film thickness of the light shielding pattern 30a was 980 mm (98.0 nm). These results are shown in Table 2.

(Example 6)
In the sixth embodiment, unlike the first to fifth embodiments, the transflective layer 20 is designed so that the transmittance at 436 nm is 60%. In this example, it is designed so that the transmittance at 436 nm of irradiated light is about 60% by adjusting the film thickness of the semi-transmissive layer 20, but the other conditions are the same as in Examples 1-5. It is.

In the same procedure as in Example 1, the light shielding layer 33 and the antireflection layer 35 were etched to form a stripe pattern composed of the light shielding pattern 30a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 6 of Example 1 was taken, and the cross section and plane were observed. From the result of cross-sectional observation, it was found that the overetch dimension was 0.40 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that no particular change was observed in the titanium nitride (TiN _x ) film as the semi-transmissive layer 20 and the film remained on the surface of the transparent substrate 10.

  Next, in the same procedure as in Example 1, the semi-transmissive layer 20 was etched to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.39 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is as small as 0.05 micrometer or less with respect to a linear pattern.

Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.13, the transmittance was 48.06% at 350 nm, 60.52% at 436 nm, and 68.30% at 500 nm.
Furthermore, as a result of measuring the film thickness, the film thickness of the semi-transmissive pattern 20a was 118 mm (11.8 nm), and the film thickness of the light shielding pattern 30a was 1010 mm (101.0 nm). These results are shown in Table 2.

The patterning property of the light-shielding pattern 30a in Examples 1 to 6 is that the overetch dimension is 0.35 to 0.40 [mu] m from the observation results of the optical microscope and the electron microscope, and the unevenness dimension of the edge portion of the linear pattern is 0.00. It was 1 μm or less. Further, in the semi-transmissive pattern 20a, the overetch dimension was 0.35 to 0.40 μm, and the pattern edge linearity was 0.05 μm or less with respect to the linear pattern. This unevenness dimension was as small as 1/40 (0.05 μm) with respect to the pattern width of 2 μm, and it was confirmed that it was a level with no problem in linearity.
In addition, the linearity of pattern etching is hindered by the reaction with the etchant at the thin film grain boundaries and the lack of adhesion between the thin film and the resist interface due to patterning without surface treatment. It is estimated that. This lack of adhesion is considered to be caused by oxidation or contamination of the surface of the thin film caused by leaving the photomask substrate 2 after the thin film is formed, and the like.

(Example 7)
In this embodiment, unlike the first to sixth embodiments, the material of the first layer (semi-transmissive layer) and the material of the second layer (light-shielding layer) are replaced, and the first etching solution (etching solution) is used. This is an example in which A) and the second etching solution (etching solution B) are replaced. The film forming process and the patterning process are basically the same as those in Examples 1 to 6.

  As in Example 1, first, a quartz substrate (transparent substrate 10) was set in a sputtering apparatus, and reactive sputtering was performed using a commercially available chromium metal target (purity 99.99% or more). In the sputtering step, the semi-transmissive layer 20 was formed by forming a thin film of a compound (CrON) composed of chromium, oxygen and nitrogen by sputtering while introducing oxygen gas and nitrogen gas. At this time, the semi-transmissive layer 20 was formed to have a transmittance of 20% at a wavelength of 436 nm.

  Next, the metal chromium target was changed to the metal titanium target, and the light shielding layer 33 was formed on the surface of the semi-transmissive layer 20 so as to have a film thickness of 700 mm (70 nm). At this time, no reactive gas was introduced, and only metal titanium (Ti) was deposited on the surface of the semi-transmissive layer 20.

Subsequently, the target was changed to a new titanium target, and the antireflection layer 35 was formed to a thickness of 300 mm (30 nm). In the sputtering step, a compound of titanium, oxygen, and nitrogen (TiON) was formed by sputtering while introducing oxygen gas and nitrogen gas.
The reflectance at this time is 35 to 38% at a wavelength of 650 nm and 9 to 10% at around 430 nm when the antireflection layer 35 is formed.

Next, the photomask substrate 2 formed in the sputtering step is taken out of the sputtering apparatus, left in a storage for one week, and then etched with an etching solution B (mixed solution of potassium hydroxide, hydrogen peroxide, and water). In the same procedure as in Example 1, a stripe pattern composed of the light shielding pattern 30a in which the light shielding layer 33 and the antireflection layer 35 were laminated was formed.
The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 6 of Example 1 was taken, and the cross section and plane were observed. From the result of cross-sectional observation, it was found that the overetch dimension was 0.39 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that there was no particular change in the chromium oxynitride (CrON) film as the semi-transmissive layer 20 and it remained on the surface of the transparent substrate 10.

Next, the semi-transmissive layer 20 was etched with an etching solution A (a mixed solution of cerium ammonium nitrate, perchloric acid, and water) in the same procedure as in Example 1 to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.38 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is 0.1 micrometer or less sufficiently with respect to a linear pattern.
Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.07, the transmittance was 7.65% at 350 nm, 18.97% at 436 nm, and 27.66% at 500 nm.
Furthermore, as a result of measuring the film thickness, the film thickness of the semi-transmissive pattern 20a was 487 mm (48.7 nm), and the film thickness of the light shielding pattern 30a was 1000 mm (100 nm). These results are shown in Table 2.

(Example 8)
In the eighth embodiment, unlike the seventh embodiment, the transflective layer 20 is designed so that the transmittance at 436 nm is 40%. In this example, the transmissivity is designed so that the transmittance of irradiated light at 436 nm is about 40% by adjusting the film thickness of the semi-transmissive layer 20, but other conditions are the same as in Example 7. .

  A stripe pattern composed of the light shielding pattern 30a in which the light shielding layer 33 and the antireflection layer 35 are laminated is formed by the same procedure as in Example 7. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 6 of Example 1 was taken, and the cross section and plane were observed. From the result of cross-sectional observation, it was found that the overetch dimension was 0.39 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that there was no particular change in the chromium oxynitride (CrON) film as the semi-transmissive layer 20 and it remained on the surface of the transparent substrate 10.

  Next, the semi-transmissive layer 20 was etched in the same procedure as in Example 7 to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.37 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is 0.1 micrometer or less sufficiently with respect to a linear pattern.

Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.05, the transmittance was 29.03% at 350 nm, 37.66% at 436 nm, and 43.48% at 500 nm.
Furthermore, as a result of measuring the film thickness, the film thickness of the semi-transmissive pattern 20a was 287 mm (28.7 nm), and the film thickness of the light shielding pattern 30a was 1020 mm (102 nm). These results are shown in Table 2.

Example 9
In the ninth embodiment, unlike the seventh and eighth embodiments, the transflective layer 20 is designed so that the transmittance at a wavelength of 436 nm is 60%. In this example, the transmittance of the irradiated light at a wavelength of 436 nm is designed to be about 60% by adjusting the film thickness of the semi-transmissive layer 20, but other conditions are the same as in Examples 7 and 8. It is the same.

  A stripe pattern composed of a light shielding pattern 30a in which the light shielding layer 33 and the antireflection layer 35 were laminated was formed by the same procedure as in Examples 7 and 8. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 6 of Example 1 was taken, and the cross section and plane were observed. As a result of cross-sectional observation, it was found that the overetch dimension was 0.38 μm. Further, from the result of frontal observation, it was found that unevenness occurred at the edge portion of the linear pattern, and the maximum and minimum widths were 0.1 μm or less. At this time, it was found that there was no particular change in the chromium oxynitride (CrON) film as the semi-transmissive layer 20 and it remained on the surface of the transparent substrate 10.

  Next, the semi-transmissive layer 20 was etched by the same procedure as in Examples 7 and 8 to form a stripe pattern composed of the semi-transmissive pattern 20a. The formed substrate was cut in the vertical direction, and an electron micrograph similar to that in FIG. 8 of Example 1 was taken, and the cross section and plane were observed. As a result, the overetch dimension was 0.36 μm. Moreover, it turned out that the uneven | corrugated dimension of an edge part is 0.1 micrometer or less sufficiently with respect to a linear pattern.

Further, the transmittance and the like were measured in the same manner as in Example 1. As a result, the optical density was 3.03, the transmittance was 48.21% at 350 nm, 59.05% at 436 nm, and 64.98% at 500 nm.
Further, as a result of measuring the film thickness, the film thickness of the semi-transmissive pattern 20a was 124 mm (12.4 nm), and the film thickness of the light shielding pattern 30a was 1010 mm (101 nm). These results are shown in Table 2.

  As shown in these Examples 7 to 9, the material of the semi-transmissive layer that is the first layer and the material of the light shielding layer that is the second layer are replaced, and the etching liquid A that is the first etching liquid and the second Even when the etching solution B as the etching solution was replaced, the same results as in Examples 1 to 6 were obtained.

  As a result, it was confirmed that it can be used as a photomask as well as the black matrix currently used for liquid crystal display elements and color filter substrates. The evaluation results of Examples 1 to 9 are shown in Table 2.

A comparative example will be described below.
(Comparative Example 1)
Comparative Example 1 is different from Examples 1 to 9, the first antireflection layer made of chromium oxide on the surface of the transparent substrate 10 (CrO _x), a light-shielding layer of metal chromium (Cr), chromium oxide ( In this example, three layers of the second antireflection layer made of CrO _x are sequentially laminated in this order. The laminated structure in this example is the same as the structure of a photomask that is generally used. That is, a general photomask may be formed by sandwiching or sandwiching one or both of the layers arranged above and below the light shielding layer depending on the degree of absorption of the light shielding layer. Often to do. In Comparative Example 1, a substrate for forming such a general photomask is employed as an object to be compared with the above embodiments.

In Comparative Example 1, the same sputtering apparatus as in Example 1 was used, a metal chromium target (purity 99.99% or more) was used instead of the metal titanium target of Example 1, and oxygen gas was used as the reactive gas. Then, chromium oxide (CrO _x ) as a first antireflection layer was directly formed on the surface of the transparent substrate 10 by reactive sputtering. Note that the degree of oxidation differs depending on the sputtering apparatus, and thus may be adjusted as appropriate by combining film formation conditions.

Next, the metal chromium target was changed to a new metal chromium target, and a light shielding layer made of metal chromium (Cr) was formed on the surface of the first antireflection layer by sputtering. This light-shielding layer has a film thickness capable of almost 100% shielding (OD> 3.0) against irradiation light. Further, a second antireflection layer made of chromium oxide (CrO _x ) was continuously formed on the surface of the light shielding layer.

  Subsequently, the laminated substrate formed in the sputtering process was taken out of the sputtering apparatus and left in a storage for one week. Subsequently, the substrate taken out from the storage was subjected to ultrasonic cleaning in each of a plurality of tanks of an alkaline detergent, a neutral detergent, and pure water, and then the same resist as in Example 1 was applied to the entire surface of the substrate. Application and temporary curing were performed. Thereafter, exposure, development, and main curing were performed using the pattern used in Example 1, and the first antireflection layer was formed using a mixed solution composed of perchloric acid, cerium ammonium nitrate, and water as the first etching solution. The light shielding layer and the second antireflection layer were etched together to form a stripe pattern.

  By observing the cross section and the plane using an electron microscope in the same manner as in Example 1, the overetching of the stripe pattern composed of the three layers at this time was evaluated. As a result, it was found from the cross-sectional observation that the overetch dimension was 0.40 μm, and from the result of the front observation, the width of the unevenness at the edge portion of the linear pattern was 0.1 μm or less.

Using another substrate that was not patterned, the optical density (OD) and the spectral reflectance as optical characteristics were measured with a self-recording spectrophotometer U-4000 manufactured by Hitachi High-Technologies in the same manner as in Example 1. As a result, the obtained optical density was 3.18, and the reflectance from the substrate surface side was 7.11% at 436 nm.
In addition, as a result of measuring the film thickness of the pattern composed of the first antireflection layer, the light shielding layer, and the second antireflection layer using a part of the etched stripe pattern, the total film thickness is 1280 mm. (128.0 nm). The results are shown in Table 2.

(Comparative Example 2)
Unlike the examples 1 to 9 and the comparative example 1, the comparative example 2 has two layers of a chromium oxide (CrO _x ) layer as an antireflection layer and a metallic chromium (Cr) layer as a light shielding layer on the surface of the transparent substrate 10. Is an example in which these are sequentially stacked in this order. In this example, for the purpose of improving the display quality of a liquid crystal display device, etc., a thin film for a black matrix provided on the outer periphery of each image (for example, the outer periphery of a pixel of red, green, blue, etc. of a color filter), several microns It has the same structure as a two-layer type photomask used for a photomask of ˜several tens of microns. The black matrix has a structure in which chromium oxide (CrO _x ) as an antireflection layer is disposed on the substrate side in order to reduce the reflectance from the viewing side opposite to the mask.

In this example, chromium oxide (CrO _x ) was laminated to a thickness of 300 mm (30.0 nm) in the same procedure as in Example 1. Subsequently, metal chromium (Cr) was laminated thereon so as to have a film thickness of 700 mm (79.0 nm).
Next, exposure, development, and main curing are performed in the same procedure as in Example 1, and a chromium oxide (CrO _x ) layer is formed using a mixed solution of perchloric acid, cerium ammonium nitrate, and water as the first etching solution. And the metal chromium (Cr) layer were etched together to form a stripe pattern.

By observing the cross section and plane using an electron microscope in the same manner as in Example 1, a stripe pattern composed of a chromium oxide (CrO _x ) layer as an antireflection layer and a metal chromium (Cr) layer as a light shielding layer at this time Of overetching was evaluated. As a result, it was found from the cross-sectional observation that the overetch dimension was 0.38 μm, and from the front observation result, the width of the unevenness at the edge portion of the linear pattern was 0.1 μm or less.

Using another substrate that was not patterned, the optical density (OD) and the spectral reflectance as optical characteristics were measured with a self-recording spectrophotometer U-4000 manufactured by Hitachi High-Technologies in the same manner as in Example 1. As a result, the obtained optical density was 3.04, and the reflectance from the substrate surface side was 7.53% at 436 nm.
Moreover, as a result of measuring the film thickness of the pattern composed of the light shielding layer and the antireflection layer using a part of the etched stripe pattern, the total film thickness was 980 mm (98.0 nm). The results are shown in Table 2.

(Comparative Example 3)
Unlike Examples 1 to 9 and Comparative Examples 1 and 2, Comparative Example 3 is an example in which only a chromium oxide (CrO _x ) layer is formed on the surface of the transparent substrate 10. Since the chromium oxide (CrO _x ) layer is etched with the same etching solution as the metal chromium (Cr) layer, a light-shielding metal chromium (Cr) layer is used when a halftone mask is formed by a conventional method. Semi-permeable chromium oxide (CrO _x ) layers were deposited separately (ie, in two portions). Therefore, in Comparative Example 3, an example in which only a chromium oxide (CrO _x ) layer having only a function as a semi-transmissive layer is formed is adopted as a comparison object with each of the above examples.

In this example, a chromium oxide (CrO _x ) layer was formed to a thickness of 300 mm (30.0 nm) by the same procedure as in Example 1.
Next, exposure, development, and main curing are performed in the same procedure as in Example 1, and a chromium oxide (CrO _x ) layer is formed using a mixed solution of perchloric acid, cerium ammonium nitrate, and water as the first etching solution. Was etched to form a stripe pattern.

By observing the cross section and the plane using an electron microscope in the same manner as in Example 1, overetching of the pattern composed of the chromium oxide (CrO _x ) layer at this time was evaluated. As a result, it was found from the cross-sectional observation that the overetch dimension was 0.38 μm, and from the front observation result, the width of the unevenness at the edge portion of the linear pattern was 0.1 μm or less.

Using another substrate that was not patterned, the optical density (OD) and the spectral transmittance as optical characteristics were measured with a self-recording spectrophotometer U-4000 manufactured by Hitachi High-Technologies in the same manner as in Example 1. The resulting optical density was 0.39 and the transmittance was 40.64% at 436 nm.
Moreover, as a result of measuring the film thickness of the pattern using a part of the etched stripe pattern, the film thickness was 290 mm (29.0 nm). The results are shown in Table 2.

(Comparative Example 4)
Comparative Example 4 is an example in which only a metal chromium (Cr) layer is formed on the surface of the transparent substrate 10, unlike Examples 1 to 9 and Comparative Examples 1 to 3. Since metallic chrome (Cr) has high reflectivity, it is used as an electrode including a wiring, a mirror, or the like, so that it can be used as a reference in comparing patterning properties with the examples.

In this example, a metal chromium (Cr) layer was formed to a thickness of 700 mm (70.0 nm) by the same procedure as in Example 1.
Next, exposure, development, and main curing are performed in the same procedure as in Example 1, and a metal chromium (Cr) layer is formed using a mixed solution composed of perchloric acid, cerium ammonium nitrate, and water as the first etching solution. Etching was performed to form a stripe pattern.

  By observing the cross section and plane using an electron microscope in the same manner as in Example 1, overetching of a pattern composed of a metal chromium (Cr) layer was evaluated at this time. As a result, it was found from the cross-sectional observation that the overetch dimension was 0.35 μm, and from the front observation result, the width of the unevenness at the edge portion of the linear pattern was 0.05 μm or less.

Using another substrate that was not patterned, the optical density (OD) and the spectral reflectance and transmittance as optical characteristics were measured with a self-recording spectrophotometer U-4000 manufactured by Hitachi High-Technologies in the same manner as in Example 1. The resulting optical density was 3.02, the transmittance was 0.092% at 436 nm, and the reflectance was 59.71%.
Moreover, as a result of measuring the film thickness of the pattern using a part of the etched stripe pattern, the total film thickness was 720 mm (72.0 nm). The results are shown in Table 2.

1 is a longitudinal sectional view of a photomask substrate according to an embodiment of the present invention. It is a longitudinal cross-sectional view of the photomask which concerns on one Embodiment of this invention. It is explanatory drawing which shows the process of patterning a photomask from the substrate for photomasks. It is explanatory drawing which shows the process of patterning a photomask. It is a longitudinal cross-sectional view of the substrate for photomasks which concerns on other embodiment of this invention. It is the electron micrograph which image | photographed the longitudinal cross-section and plane of the photomask after light-shielding pattern formation. It is the optical microscope photograph which image | photographed the plane after cross pattern formation. It is the electron micrograph which image | photographed the longitudinal cross-section and plane of the photomask after semi-transmissive pattern formation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photomask 2 ... Photomask substrate 1a ... Shading part 1b ... Semi-transmission part 1c ... Transparent part 10 ... Transparent substrate 20 ... Semi-transmission layer (first layer)
20a..Translucent pattern 30..Composite layer (second layer)
30a ·· Light-shielding pattern 33 · · Light-shielding layer 33a · · Light-shielding layer pattern 35 · · Anti-reflection layer 35a · · Anti-reflection layer pattern 50 · · Resist 60 · · Mask master 70 · · Resist 80 · · Mask master 90 · · Metal compound layer

Claims (13)

A transparent substrate, a first layer formed on the transparent substrate and semi-transmissive to the irradiation light, a second layer formed on the first layer and substantially blocking the irradiation light, A light-shielding portion where the light-shielding pattern formed by the second layer is exposed on the surface, a semi-transmissive portion where the semi-transmissive pattern formed by the first layer is exposed on the surface, and the transparent substrate is the surface A photomask substrate capable of forming a transparent portion exposed to
The first layer is insoluble or hardly soluble in the first etching solution and more easily soluble in the second etching solution than the second layer,
The photomask, wherein the second layer is more soluble in the first etching solution than the first layer and is insoluble or hardly soluble in the second etching solution. Substrate.   The photomask substrate according to claim 1, wherein the first layer is directly formed on the transparent substrate.   2. The photomask substrate according to claim 1, wherein the first layer is formed on the transparent substrate through a metal compound layer having a transmittance of 70% or more and less than 100%.   4. The photomask substrate according to claim 1, wherein the first etching solution is a mixed solution of cerium ammonium nitrate, perchloric acid, and water. 5.   5. The photomask substrate according to claim 1, wherein the second etching solution is a mixed solution of potassium hydroxide, hydrogen peroxide, and water.   The said 1st layer has as a main component 1 or 2 or more components selected from the group which consists of titanium, a titanium nitride, and a titanium oxynitride, The any one of Claims 1-5 characterized by the above-mentioned. The substrate for photomasks described in 1.   The said 2nd layer has as a main component 1 or 2 or more components selected from the group which consists of chromium, chromium oxide, chromium nitride, and chromium oxynitride of Claim 1-6 characterized by the above-mentioned. The photomask substrate according to any one of the above.   8. The photomask according to claim 1, wherein the second layer includes a light-shielding layer and an antireflection layer formed on a surface side of the light-shielding layer. substrate.   9. The photomask according to claim 8, wherein the antireflection layer contains, as a main component, one or more components selected from the group consisting of chromium oxide, chromium nitride, and chromium oxynitride. substrate. The first layer is a layer mainly composed of one or more components selected from the group consisting of chromium, chromium oxide, chromium nitride, and chromium oxynitride,
The second layer is a layer mainly composed of one or more components selected from the group consisting of titanium, titanium nitride, and titanium oxynitride,
The first etching solution is a mixed solution of potassium hydroxide, hydrogen peroxide and water,
10. The photomask substrate according to claim 1, wherein the second etching solution is a mixed solution of cerium ammonium nitrate, perchloric acid, and water.   The photomask substrate according to claim 1, wherein the first layer and the second layer are formed by a sputtering method, an ion plating method, or an evaporation method. A transparent substrate, a first layer formed on the transparent substrate and semi-transmissive to the irradiation light, a second layer formed on the first layer and substantially blocking the irradiation light, A photomask formed of a photomask substrate comprising:
The first layer is insoluble or hardly soluble in the first etching solution and more easily soluble in the second etching solution than the second layer,
The second layer is more soluble in the first etching solution than the first layer and insoluble or hardly soluble in the second etching solution,
The photomask includes
A light shielding part in which a light shielding pattern formed by etching the second layer with the first etching solution is exposed on the surface;
A semi-transmissive part in which a semi-transmissive pattern formed by etching the first layer with the second etching solution is exposed on the surface;
The second layer and the first layer are etched by the first etching solution and the second etching solution, respectively, and a transparent portion where the transparent substrate is exposed on the surface is formed. A photomask. A method of manufacturing a photomask according to claim 12,
A first resist coating step of coating a resist on the surface of the second layer;
A first exposure step of exposing the resist coated in the first resist coating step through a mask on which a first mask pattern is formed;
A first resist removal step of removing an exposed portion of the resist after the first exposure step;
A first etching step of etching the second layer exposed in the region where the resist is removed with the first etching solution to form the light-shielding pattern;
A first resist stripping step of stripping off the resist remaining in the first resist removal step;
A second resist coating step for coating the surface with the resist again;
A second exposure step of exposing the resist coated in the second resist coating step through a mask on which a second mask pattern is formed;
A second resist removal step of removing an exposed portion of the resist after the second exposure step;
A second etching step of etching the first layer exposed in the region where the resist has been removed with the second etching solution to form the semi-transmissive pattern;
And a second resist stripping step of stripping the resist remaining in the second resist removal step.

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