TWI726289B - Mask blanks, photomask, and method of manufacturing mask blanks - Google Patents

Abstract

A mask blanks of the invention includes a transparent substrate, a light shielding layer that is formed on a surface of the transparent substrate and has chrome as a main component, an antireflection layer that contains a large amount of oxygen as compared with that of the light shielding layer, and an intermediate layer that contains a large amount of carbon as compared with those of the antireflection layer and the light shielding layer. A sheet resistance of the mask blanks is set lower than 10Ω/sq.

Description

Mask substrate, mask, and manufacturing method of mask substrate

The present invention relates to a photomask substrate, a photomask, and a manufacturing method of the photomask substrate, and particularly relates to a better technology for antistatic.

A photomask suitable for large substrates for FPD (flat panel display) is known. This kind of photomask is as described in Patent Document 1. In a photomask base formed by forming a light-shielding film or semi-transmissive film containing metals such as chromium on a glass substrate, a desired pattern is formed through a patterning process to form a Binary mask.

Thereby, a photomask in which a light-transmitting area where the transparent substrate is exposed without a light-shielding pattern and a light-shielding area formed by laminating a light-shielding layer containing chromium on the transparent substrate are sequentially arranged adjacently.

This type of photomask may cause static electricity to accumulate in the photomask during the manufacturing process of the photomask, during the cleaning process of the photomask, or during the transport process of the photomask, and the photomask may partially undergo electrostatic breakdown. The above situation has become a problem.

In recent years, the high-definition of liquid crystal displays and organic EL (Electro-Luminescence) display panels has been greatly advanced. With this, the miniaturization of photomasks has also progressed. As a result, the following problem arises: due to the miniaturization of the mask, the distance between the isolated patterns adjacent to each other becomes smaller, and therefore the probability of occurrence of electrostatic breakdown becomes higher.

Furthermore, the following problem has arisen: as the size of the photomask is increased along with the increase in the size of the FPD and the like, the area of the photomask has increased, resulting in an increase in the number of occurrences of electrostatic breakdown.

In order to solve this problem, Patent Document 2 and Patent Document 3 describe a technique in which a transparent conductive film is formed under or above the light-shielding film or semi-transmissive film constituting the photomask in order not to form an isolated pattern in the photomask.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2007-212738

[Patent Document 2] Japanese Patent Laid-Open No. 2008-241921

[Patent Document 3] Japanese Patent Laid-Open No. 2009-86383

However, in the techniques described in Patent Document 2 and Patent Document 3, there is a problem in that the transmittance decreases in the exposure step due to the formed transparent conductive film. Furthermore, in these technologies, there is the following problem: in the mask forming step or the cleaning step, the transparent conductive material is removed by etching. Electric film, resulting in a decrease in conductivity and electrostatic breakdown.

The present invention was completed in view of the above circumstances, and intends to achieve the following objects.

1. Prevent the occurrence of electrostatic breakdown in the mask.

2. At the same time, it prevents the degradation of the optical characteristics in the mask.

The inventors of the present invention made diligent studies and found that by reducing the resistance value of the light shielding film forming the mask, the incidence of electrostatic breakdown can be suppressed.

It is known that by setting the sheet resistance value of the light-shielding film to 10Ω/sq or less, the occurrence rate of electrostatic breakdown can be greatly suppressed. In this way, by setting the sheet resistance of the light-shielding film to 10Ω/sq or less, a photomask that can prevent electrostatic breakdown can be formed.

When forming a photomask, usually, it is generally made of a double-layer structure with a chromium oxide film used as an anti-reflection layer on the upper side (surface side) and a chromium film on the lower side (side of the glass substrate).

Here, when the light-shielding film is formed using chromium, in order to set the resistance value of the light-shielding film within the above-mentioned range, it is preferable to set the film thickness of the light-shielding film to 100 nm or more.

In this case, the chromium oxide film used as the anti-reflection layer provided on the upper side (surface side) preferably has a film thickness range of 20 to 30 nm, and the film surface of the chromium oxide film is low-reflective.

However, it is known that when a chrome mask base with a double-layer structure including an anti-reflection layer on the surface side and a light-shielding layer on the glass substrate side is used to form a mask, the following problem occurs: When the film thickness is more than 100nm, the cross-sectional shape during patterning during wet etching produces a skirt-like bottom.

Furthermore, the so-called skirt bottom refers to a situation where the side surface of the light shielding layer is inclined and the lower side (glass substrate side) becomes larger than the upper side (surface side), that is, the cross-sectional shape of the light shielding layer pattern becomes substantially trapezoidal. In this way, if a skirt-like bottom is produced, when the surface of the mask is visually viewed, the oxide, that is, the anti-reflection layer, is black, and the light-shielding layer on the lower side has metallic luster, so the edge of the light-shielding pattern has luster. Therefore, by visual inspection, the generation of the skirt-like bottom can be recognized, and it can be seen that the pattern size is inaccurate and defective as a mask.

Based on these circumstances, the inventors of the present invention realized a photomask substrate capable of manufacturing a photomask that can make the resistance value of the light-shielding film in a low range and can prevent the generation of skirt-like bottoms.

The photomask base of the present invention includes: a transparent substrate; a light-shielding layer formed on the surface of the above-mentioned transparent substrate and mainly composed of chromium; an anti-reflection layer which contains more oxygen than the above-mentioned light-shielding layer; and an intermediate layer, which Compared with the above-mentioned anti-reflection layer and the above-mentioned light-shielding layer, it contains more carbon; and the sheet resistance is set to be less than 10Ω/sq, thereby solving the above-mentioned problem.

In the present invention, it is more preferable that the carbon content in the intermediate layer is set to be more than twice that of the light shielding layer.

In the present invention, the carbon content in the intermediate layer can be set to 14.5 atm% or more.

More preferably, the photomask of the present invention is made of any one of the above-mentioned photomask substrates, and the light-shielding pattern formed by removing the light-transmitting area from the light-shielding layer is the same as the wall surface of the light-transmitting area The angle of contact with the surface of the above-mentioned transparent substrate is set to 80° or more.

The manufacturing method of the photomask substrate of the present invention is to manufacture the photomask substrate of any one of the above. When the intermediate layer is formed, compared with the film formation of the antireflection layer and the light-shielding layer, it can contain carbon. The partial pressure of the gas is set to be higher.

The photomask base of the present invention includes: a transparent substrate; a light-shielding layer formed on the surface of the above-mentioned transparent substrate and mainly composed of chromium; an anti-reflection layer which contains more oxygen than the above-mentioned light-shielding layer; and an intermediate layer, which Compared with the above-mentioned anti-reflection layer and the above-mentioned light-shielding layer, it contains more carbon; and the sheet resistance is set to be less than 10Ω/sq. Thereby, it has the same optical characteristics as a double-layered mask with a chromium oxide film as an anti-reflection layer on the surface side (upper side) and a chromium film as a light-shielding layer on the lower layer, and can exhibit lower resistivity And reduce the occurrence of electrostatic breakdown. Furthermore, by making a three-layer structure and using a chromium film with a higher carbon concentration or oxygen concentration in the intermediate layer, the etching rate of the chromium film in the intermediate layer can be lower than that of the chromium film on the side of the transparent substrate. As a result, it is possible to provide a photomask substrate capable of manufacturing a photomask whose skirt-like bottom is relatively low even when the chromium film thickness of the low sheet resistance which can reduce the influence of electrostatic breakdown is 100nm or more. less. As a result, the unevenness of the pattern line width in the mask can also be reduced.

Here, the chromium film thickness refers to the film thickness including the film thickness of the intermediate layer and the film thickness of the light-shielding layer other than the chromium oxide film used as the anti-reflection layer, which contributes to the sheet resistance.

In the present invention, by setting the carbon content in the intermediate layer to more than twice that of the light-shielding layer, the etching rate of the chromium film of the intermediate layer can be lower than that of the chromium film on the glass substrate side (transparent substrate side) In the etching during pattern formation, the amount of etching in the intermediate layer is smaller than that in the light-shielding layer, so that it is located on the upper side (surface side, outside) of the light-shielding layer and is exposed to the etchant In the intermediate layer with a longer time, the amount of side etching is reduced, and the inclination of the boundary side of the light-shielding pattern and the area removed by etching is formed into a nearly vertical state.

In the present invention, by setting the carbon content in the intermediate layer to 14.5atm% or more, the etching rate of the chromium film of the intermediate layer can be lower than the etching rate of the chromium film on the glass substrate side (transparent substrate side). In the etching during pattern formation, the amount of etching in the intermediate layer is smaller than that in the light-shielding layer, so that the intermediate layer is located on the upper side (surface side, outside) of the light-shielding layer and exposed to the etchant for a longer time. The amount of side etching is controlled in a specific state, and the inclination of the boundary side between the light-shielding area and the light-transmitting area, that is, the boundary side of the light-shielding pattern and the light-transmitting area removed by etching, is set to a nearly vertical state, and the shape is formed without a skirt. The state of the bottom.

The photomask of the present invention is manufactured from any one of the above-mentioned photomask bases, and the light-shielding pattern formed by removing the light-transmitting area from the light-shielding layer is in contact with the wall surface of the light-transmitting area and the surface of the transparent substrate The angle is set to 80° or more. Thereby, the unevenness of the line width in the light-shielding pattern can be reduced.

The manufacturing method of the photomask substrate of the present invention is to manufacture the photomask substrate of any one of the above. When the intermediate layer is formed, the carbon-containing gas is compared with the film formation of the antireflection layer and the light-shielding layer. The partial pressure is set to be higher. By this, the carbon content of the intermediate layer can be set to a specific state, whereby the carbon content of the intermediate layer can be set to be more than that of the anti-reflection layer and the light-shielding layer, so that the etching rate of the chromium film of the intermediate layer is lower than that of the glass The etching rate of the chromium film on the substrate side (transparent substrate side) during pattern formation is such that the etching amount in the intermediate layer is smaller than that of the light shielding layer, so that it is located on the upper side (surface side, outside) of the light shielding layer. In the intermediate layer where the time of exposure to the etchant becomes longer, The amount of side etching is reduced, and the inclination of the side surface of the boundary between the light-shielding pattern and the area removed by etching is formed into a nearly vertical state.

In the present invention, as long as the etching rate of the chromium layer on the lower side (transparent substrate side) is controlled in a manner that changes in the film thickness direction, a good cross-section can be obtained that suppresses the generation of the skirt-like bottom of the cross-sectional shape of the light-shielding pattern shape. Specifically, the concentration of carbon or oxygen, or both carbon and oxygen in the intermediate layer containing chromium is controlled to vary in the film thickness direction so that the upper side (surface side) of the light shielding layer (chromium layer) That is, the carbon concentration or oxygen concentration of the intermediate layer is greater than that of the light-shielding layer. Thereby, the etching rate in the intermediate layer on the side of the anti-reflection layer can be slower than the etching rate in the light shielding layer on the side of the transparent substrate. By controlling the carbon concentration or oxygen concentration in the chromium film in this way, a cross-sectional shape with fewer skirt-like bottoms can be obtained.

In the present invention, the intermediate layer may be a single layer, or may be a structure in which multiple layers are laminated. Furthermore, in the intermediate layer formed as a multilayer, the carbon content can be made different from one to another.

The present invention is used in the manufacture of FPD and other photomask bases suitable for large-scale substrates, and can be used as a binary photomask to be applied to a photomask with a chromium-containing layer as a light-shielding film.

In the present invention, as a method of controlling the carbon concentration of the chromium layer, the chromium layer can be made into a layered structure, and the carbon concentration can be changed layer by layer as the layers are stacked from the lower side to the upper side. Alternatively, the flow of the reactive gas during film formation may be used to change the partial pressure of the carbon-containing gas in the reactive gas by increasing the partial pressure of the carbon-containing gas, thereby controlling the carbon concentration (carbon concentration).

Furthermore, in the present invention, a low-reflectivity layer, an anti-reflection layer, a protective layer, etc. may also be provided. In addition, the stacking order of these layers can be appropriately set.

According to the present invention, it is possible to provide the effect of providing a photomask substrate that can reduce the influence of electrostatic breakdown and has fewer skirt-like bottoms.

1: photomask

1B: Mask base

2: Glass substrate (transparent substrate)

2A: Transmissive area

3: shading pattern

3B: shading layer

4: shading pattern

4B: Middle layer

5: Shading pattern

5B: Anti-reflective layer

S10: Manufacturing device

S11: load room

S11a: Conveying device

S11f: Exhaust device

S12: Film forming chamber (vacuum processing chamber)

S12a: Substrate holding device

S12g: gas barrier

S13: Film Formation Department

S13b: target

S13c: Cathode electrode (backing plate)

S13d: power supply

S13e: Gas introduction device

S13f: High vacuum exhaust device

S14: Film Formation Department

S14b: target

S14c: Cathode electrode (backing plate)

S14d: power supply

S14e: gas introduction device

S14f: High vacuum exhaust device

S15: Film Formation Department

S15b: target

S15c: Cathode electrode (backing plate)

S15d: power supply

S15e: gas introduction device

S15f: High vacuum exhaust device

S16: Unloading room

S16a: Conveying device

S16f: Exhaust device

S17: Closed device

S18: Closed device

θ: cone angle

Fig. 1 is a cross-sectional view showing a photomask substrate according to an embodiment of the present invention.

Fig. 2 is a schematic diagram showing a manufacturing apparatus (film forming apparatus) used in a method of manufacturing a photomask substrate according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view of a photomask showing an embodiment of the present invention.

4 is a cross-sectional view for explaining the side etching in the manufacturing method of the photomask according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view for explaining the skirt-shaped bottom in the previous manufacturing method of the photomask.

6 is a graph showing the relationship between the thickness of the chromium film and the taper angle in the manufacturing method of the mask substrate according to the embodiment of the present invention.

FIG. 7 is a graph showing the relationship between the sheet resistance and the film thickness of the chromium layer in the manufacturing method of the photomask substrate according to the embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the sheet resistance and the occurrence rate of electrostatic breakdown in the manufacturing method of the photomask substrate according to the embodiment of the present invention.

Hereinafter, based on the drawings, the photomask substrate, the photomask, and the photomask base of the embodiment of the present invention The manufacturing method of the bottom is explained.

FIG. 1 is a cross-sectional view showing the mask substrate in this embodiment. In FIG. 1, the symbol 1B is the mask substrate.

As shown in FIG. 1, the mask base 1B of this embodiment includes a light-shielding layer 3B laminated on a glass substrate (transparent substrate) 2, an intermediate layer 4B laminated on the light-shielding layer 3B, and an anti-reflection layer 5B laminated on the intermediate layer 4B .

As the glass substrate 2, a material excellent in transparency and optical isotropy is used. For example, a quartz glass substrate can be used. The size of the glass substrate 2 is not particularly limited. The size of the glass substrate 2 is appropriately selected according to the substrate to be exposed using the photomask (for example, LCD (liquid crystal display), plasma display, organic EL (electroluminescence) display, etc. FPD substrates, etc.). In this embodiment, it can be applied to a rectangular substrate with a side of about 100 mm and a side of 2000 mm or more. Furthermore, a substrate with a thickness of several mm or a substrate with a thickness of 10 mm or more can also be used.

In addition, the flatness of the glass substrate 2 can also be reduced by grinding the surface of the glass substrate 2. The flatness of the glass substrate 2 can be set to 20 μm or less, for example. As a result, the focal depth of the photomask becomes deeper, which makes a great contribution to the formation of fine and high-precision patterns. Furthermore, the flatness is relatively good at a small value of 10 μm or less.

The light-shielding layer 3B is a layer containing Cr (chromium) as a main component, and further contains C (carbon) and N (nitrogen). Furthermore, the light-shielding layer 2B may have a different composition in the thickness direction. In this case, as the light-shielding layer 2B, a layer selected from Cr monomer and Cr oxides, nitrides, carbides, and nitrogen It is composed of one or two or more of oxides, carbonitrides, and oxycarbonitrides.

As described below, the thickness of the light-shielding layer 3B and the composition ratio (atm%) of Cr, N, C, O, etc. are set in a way to obtain specific optical characteristics and resistivity.

The intermediate layer 4B is a layer containing Cr (chromium) like the light shielding layer 3B, and further contains C (carbon). In the intermediate layer 4B, as described below, it is set so that the carbon content (carbon concentration) is higher than that of the light shielding layer 3B and the anti-reflection layer 5B. Specifically, the carbon content rate (carbon concentration) can be set to 14.5 atm% or more, and can be set to be more than twice the carbon content rate (carbon concentration) in the light shielding layer 3B and the anti-reflection layer 5B.

The anti-reflection layer 5B is a chromium oxide film containing O (oxygen) similarly to the light-shielding layer 3B, and may further contain N (nitrogen). The film thickness of the anti-reflection layer 5B is set according to the exposure wavelength when used as a mask in the exposure step, and the required optical characteristics, reflectance, etc. specified by the exposure wavelength. For example, it can be set to a thickness of about 25 nm. At the same time, in order to set the reflectance, the oxygen content rate must also be set to a specific range. Specifically, the oxygen content rate is set so that it becomes an oxygen content rate of about 30 atm% or more.

The photomask base 1B of this embodiment can be used for manufacturing the photomask for patterning of the glass substrate for FPD, for example.

In addition, the total film thickness of the light shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B of the mask base 1B of this embodiment is set to 100 nm or more, preferably 150 nm or more, and more preferably 200 nm or more.

In addition, the total sheet resistance of the light-shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B of the mask base 1B of this embodiment is set to 10Ω/sq. The sheet resistance is based on the light shielding layer 3B and the middle Film thickness setting of layer 4B.

The manufacturing method of the photomask base 1B of this embodiment is to form the light-shielding layer 3B and the intermediate layer 4B on the glass substrate (transparent substrate) 2, and then form the anti-reflection layer 5B. Furthermore, when a protective layer, a low reflection layer, an anti-reflection layer, an etching stop layer, etc. are laminated in addition to the light-shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B, the manufacturing method of the photomask substrate may include these laminated layers step.

Hereinafter, the manufacturing method of the photomask substrate in this embodiment will be described based on the drawings.

FIG. 2 is a schematic diagram showing the manufacturing apparatus used in the manufacturing method of the photomask substrate in this embodiment.

The mask substrate 1B in this embodiment is manufactured by the manufacturing apparatus shown in FIG. 2.

The manufacturing apparatus S10 shown in FIG. 2 is set as a reciprocating sputtering apparatus, which includes a load chamber S11, an unloading chamber S16, and a film forming chamber connected to the load chamber S11 via a sealing device S17 and connected to the unloading chamber S16 via a sealing device S18 ( Vacuum processing chamber) S12.

The load chamber S11 is provided with a conveying device S11a that conveys the glass substrate 2 carried in from the outside of the manufacturing device S10 to the film forming chamber S12, and an exhaust device S11f such as a rotary pump that roughly evacuates the chamber. The unloading chamber S16 is provided with a conveying device S16a that conveys the glass substrate 2 that has been film-formed to the outside from the film forming chamber S12, and an exhaust device S16f such as a rotary pump that roughly evacuates the chamber.

The film forming chamber S12 is provided with a substrate holding device S12a and three-stage film forming sections S13, S14, and S15 as devices corresponding to three film forming processes.

The substrate holding device S12a holds the glass substrate 2 so that the glass substrate 2 conveyed by the conveying device S11a faces the targets S13b, S14b, and S15b during the film formation process. In addition, the substrate holding device S12a is configured to be able to carry in the glass substrate 2 from the load chamber S11 to the film formation chamber S12, and is configured to be able to carry the glass substrate 2 out of the film formation chamber S12 to the unloading chamber S16.

At a position of the film forming chamber S12 close to the load chamber S11, as the first stage of the three film forming sections S13, S14, and S15, the film forming section S13 for supplying the film forming material is provided with a cathode electrode ( Backing plate) S13c, a power supply S13d that applies a negative potential sputtering voltage to the cathode electrode S13c, a gas introduction device S13e that introduces gas into the vicinity of the cathode electrode S13c in the film forming chamber S12, and a key point in the film forming chamber S12 A high-vacuum exhaust device S13f such as a turbo molecular pump that evacuates the vicinity of the cathode electrode S13c to a high degree.

In addition, at an intermediate position between the load chamber S11 and the unloading chamber S16 of the film forming chamber S12, the film forming section S14 for supplying the film forming material as the second stage of the three film forming sections S13, S14, S15 is provided with The cathode electrode (backing plate) S14c of the target S14b, the power supply S14d for applying a negative potential sputtering voltage to the cathode electrode S14c, the gas introduction device S14e that mainly introduces gas to the vicinity of the cathode electrode S14c in the film forming chamber S12, and In the film forming chamber S12, a high-vacuum exhaust device S14f such as a turbo molecular pump that evacuates the vicinity of the cathode electrode S14c to a high degree is focused.

Furthermore, the position of the film forming chamber S12 close to the unloading chamber S16 is used as a three-stage film forming part The third stage of S13, S14, S15, the film forming section S15 that supplies the film forming material, is provided with a cathode electrode (backing plate) S15c with a target S15b, and a power supply S15d for applying a negative potential sputtering voltage to the cathode electrode S15c A gas introduction device S15e that mainly introduces gas to the vicinity of the cathode electrode S15c in the film forming chamber S12, and a high-vacuum exhaust device S15f such as a turbo molecular pump that evacuates the vicinity of the cathode electrode S15c in the film forming chamber S12. .

In the film forming chamber S12, in the vicinity of the cathode electrodes S13c, S14c, S15c, there is provided gas that suppresses the flow of gas to prevent the gas supplied from the gas introduction devices S13e, S14e, S15e from being mixed into the adjacent film forming parts S13, S14, S15. Protective wall S12g. The gas barrier walls S12g are configured to be movable between the adjacent film forming parts S13, S14, and S15 by the substrate holding device S12a.

In each of the three film forming sections S13, S14, and S15 in the film forming chamber S12, set the composition and conditions (target, gas type, film forming conditions, etc.) necessary for sequential film formation on the glass substrate 2 .

In this embodiment, the film-forming part S13 corresponds to the film formation of the light shielding layer 3B, the film-forming part S14 corresponds to the film formation of the intermediate layer 4B, and the film-forming part S15 corresponds to the film formation of the anti-reflection layer 5B.

Specifically, in the film forming part S13, the target S13b contains a material containing chromium as a composition necessary for forming the light shielding layer 3B on the glass substrate 2.

At the same time, in the film forming section S13, the gas system supplied from the gas introducing device S13e is selected corresponding to the film forming of the light shielding layer 3B. Specifically, the processing gas contains carbon, nitrogen, oxygen, etc., and is set to a specific gas partial pressure along with a sputtering gas such as argon. In addition, according to the film forming conditions, the high vacuum exhaust device S13f is used for exhaustion.

In addition, in the film forming portion S13, the sputtering voltage applied from the power source S13d to the backing plate S13c is set in accordance with the film forming of the light shielding layer 3B.

In addition, in the film forming part S14, the target S14b contains a material containing chromium as a composition necessary for forming the intermediate layer 4B on the light shielding layer 3B.

At the same time, in the film forming section S14, the gas system supplied from the gas introducing device S14e is selected corresponding to the film forming of the intermediate layer 4B. Specifically, the processing gas contains carbon, nitrogen, oxygen, etc., and is set to a specific gas partial pressure together with a sputtering gas such as argon. In addition, according to the film formation conditions, the high vacuum exhaust device S14f is used for exhaustion.

In addition, in the film forming portion S14, the sputtering voltage applied from the power source S14d to the backing plate S14c is set in accordance with the film forming of the intermediate layer 4B.

In addition, in the film forming part S15, the target S15b contains a material containing chromium as a composition necessary for forming the antireflection layer 5B on the intermediate layer 4B.

At the same time, in the film forming part S15, the gas system supplied from the gas introducing device S15e is selected corresponding to the film forming of the anti-reflection layer 5B. Specifically, the processing gas contains carbon, nitrogen, oxygen, etc., and is set to a specific gas partial pressure together with a sputtering gas such as argon. In addition, according to the film forming conditions, the high vacuum exhaust device S15f is used for exhausting.

In addition, in the film forming section S15, the sputtering voltage applied from the power source S15d to the backing plate S15c is set in accordance with the film forming of the anti-reflection layer 5B.

In the manufacturing apparatus S10 shown in FIG. 2, for the glass substrate 2 carried in from the load chamber S11 by the conveying device S11a, the substrate holding device is used in the film forming chamber (vacuum processing chamber) S12. In S12a, three stages of sputtering film formation are performed on the conveying side. After that, the glass substrate 2 whose film formation has been completed is carried out from the unloading chamber S16 to the outside by the conveying device S16a.

In the film forming step, in the film forming section S13, sputtering gas and reaction gas are supplied from the gas introduction device S13e to the vicinity of the backing plate S13c of the film forming chamber S12, and the sputtering voltage is applied to the cathode from an external power source Electrode S13c. In addition, a specific magnetic field can also be formed on the target S13b by a magnetron magnetic circuit. The ions of the sputtering gas excited by the plasma near the backing plate S13c in the film forming chamber S12 collide with the target S13b of the cathode electrode S13c to cause the particles of the film forming material to jump out. Furthermore, the particles that jump out are combined with the reaction gas, and then adhere to the glass substrate 2, thereby forming a light shielding layer 3B with a specific composition on the surface of the glass substrate 2.

Similarly, in the film forming section S14, sputtering gas and reaction gas are supplied from the gas introduction device S14e to the vicinity of the backing plate S14c of the film forming chamber S12, and the sputtering voltage is applied to the cathode electrode S14c from an external power source. In addition, a specific magnetic field can also be formed on the target S14b by a magnetron magnetic circuit. The ions of the sputtering gas excited by the plasma in the vicinity of the backing plate S14c in the film forming chamber S12 collide with the target S14b of the cathode electrode S14c to cause the particles of the film forming material to jump out. Moreover, the particles that jump out are combined with the reaction gas, and then adhere to the glass substrate 2, thereby forming the intermediate layer 4B on the surface of the glass substrate 2 with a specific composition.

Similarly, in the film forming section S15, sputtering gas and reaction gas are supplied from the gas introduction device S15e to the vicinity of the backing plate S15c of the film forming chamber S12, and the sputtering voltage is applied to the cathode electrode S15c from an external power source. In addition, a specific magnetic field can also be formed on the target S15b by a magnetron magnetic circuit. The ion and anion of the sputtering gas excited by the plasma near the backing plate S15c in the film forming chamber S12 The target S15b of the electrode S15c collides to cause the particles of the film-forming material to jump out. Moreover, the particles that jump out are combined with the reaction gas, and then adhere to the glass substrate 2, thereby forming an anti-reflection layer 5B with a specific composition on the surface of the glass substrate 2.

At this time, in the film formation of the light shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B, different amounts of carbon-containing gas, nitrogen, and oxygen-containing gas are supplied from the gas introduction devices S13e, S14e, and S15e to control the division of each gas. Press the way to switch, and set its composition within the set range.

Here, examples of the carbon-containing gas include CO ₂ (carbon dioxide), CH ₄ (methane), C ₂ H ₆ (ethane), CO (carbon monoxide), and the like. Examples of the oxygen-containing gas include CO ₂ (carbon dioxide), O ₂ (oxygen), N ₂ O (nitrous oxide), NO (nitrogen monoxide), and the like.

Furthermore, in the film formation of the light shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B, the targets S13b, S14b, and S15b can be replaced as needed.

Furthermore, when other films are laminated in addition to the light-shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B, the film is formed by sputtering under the sputtering conditions such as the corresponding target and gas, or The corresponding films are laminated by other film forming methods to manufacture the mask substrate 1B of this embodiment.

In the mask substrate 1B for the antistatic binary chromium mask of this embodiment, it is set so that the carbon concentration in the intermediate layer 4B is higher than the carbon concentration in the light-shielding layer 3B and the anti-reflection layer 5B. Specifically, it is set so that the carbon concentration in the intermediate layer 4B is about 2 times higher or higher than the carbon concentration of the light-shielding layer 3B and the anti-reflection layer 5B.

That is, the partial pressure of the carbon-containing gas supplied from the gas introduction devices S13e and S15e during the film formation of the light-shielding layer 3B and the anti-reflection layer 5B is increased by the gas introduction device S14e during the film formation of the intermediate layer 4B. The partial pressure of the supplied carbon-containing gas realizes the above composition ratio.

Alternatively, the gas flow rate of the carbon-containing gas supplied from the gas introduction devices S13e and S15e during the film formation of the light-shielding layer 3B and the anti-reflection layer 5B can be increased to increase the gas introduction during the film formation of the intermediate layer 4B. The gas flow rate of the carbon-containing gas supplied by the device S14e realizes the above composition ratio.

As a result, the intermediate layer 4B is formed in a manner that has a lower side etching rate when the wet etching becomes a subsequent step.

Furthermore, according to the composition ratio of nitrogen and oxygen in the film, the partial pressure of each gas is set to form a specific film.

Fig. 3 is a cross-sectional view showing the mask in this embodiment.

In the photomask 1 in this embodiment, as shown in FIG. 3, the light-shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B of the photomask base 1B are patterned.

Hereinafter, the manufacturing method of manufacturing the photomask (binary photomask) 1 from the photomask substrate 1B of this embodiment is demonstrated.

A photoresist layer is formed on the outermost surface of the mask substrate 1B. The photoresist layer can be positive or negative type. As the photoresist layer, a liquid resist is used.

Then, by exposing and developing the photoresist layer, a resist pattern is formed on the outer side of the anti-reflection layer 5B. The resist pattern functions as an etching mask for the light-shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B, and the shape is appropriately determined according to the etching patterns of the light-shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B. For example, in the light-transmitting area 2A, it is set to have a shape having an opening width corresponding to the opening width of the light-shielding pattern to be formed.

Then, the light-shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B are wet-etched using an etchant through this resist pattern, and the light-shielding patterns 3, 4, and 5 are formed. As the etching solution, an etching solution containing secondary cerium ammonium nitrate can be used. For example, it is preferable to use secondary cerium ammonium nitrate containing acids such as nitric acid or perchloric acid.

Here, the etching in the light shielding layer 3B, the intermediate layer 4B, and the anti-reflection layer 5B will be discussed.

4 is a cross-sectional view for explaining the etching state in the manufacturing method of the photomask of this embodiment, and FIG. 5 is a cross-sectional view for explaining the etching state in the previous manufacturing method of the photomask.

In this embodiment, a film thickness of about 200 nm exceeding 100 nm is assumed as the thickness of the chromium film to be etched. This is to obtain the low sheet resistance required to prevent electrostatic breakdown.

Here, first consider the case where the intermediate layer 4B is not provided but is a two-layer structure of the anti-reflection layer 5B and the light shielding layer 3B, ensuring that the area where the glass substrate 2 is exposed is required as a pattern opening. The state of inches.

In this case, since the etching rate in the film thickness direction in the light-shielding layer 3B is constant, as the etching in the film thickness direction in the light-shielding layer 3B progresses, the corresponding lateral side etching will proceed to a predetermined amount or more. Therefore, when the transparent area 2A exposed by the glass substrate 2 is secured as the size necessary for the pattern opening, the lateral side etching amount on the outer side (upper side) in the film thickness direction is greater than the lateral side etching on the inner side (lower side) in the film thickness direction. The amount of side etching.

As a result, as shown in FIG. 5, the side surface of the light-shielding patterns 3, 4, and 5 facing the light-transmitting region 2A side (the surface inclined at an angle θ with respect to the surface of the light-transmitting region 2A in FIG. 5) is from the glass substrate 2 side Lean in a way back to the outside (upper side). In this skirt bottom state, the angle (taper angle) θ formed by the light shielding patterns 3, 4, 5 and the surface of the glass substrate 2 becomes sharp, for example, it may become about 40°.

In contrast, as in this embodiment, the etching rate of the intermediate layer 4B is set to be lower than the etching rate of the light-shielding layer 3B, so that even when the etching in the film thickness direction of the light-shielding layer 3B is performed, the corresponding lateral direction The side etching in the intermediate layer 4B also does not proceed beyond the prescribed amount.

As a result, as shown in FIG. 4, the side surfaces of the light-shielding patterns 3, 4, and 5 facing the light-transmitting area 2A side (the surface inclined at an angle θ with respect to the surface of the light-transmitting area 2A in FIG. 4) are not too far from the glass substrate 2 The side recedes toward the outside (upper side), and is formed approximately vertically. In this state, the angle θ formed by the light shielding patterns 3, 4, 5 and the surface of the glass substrate 2 becomes larger. Here, for example, it is preferable to make the light-shielding patterns 3, 4, 5 and The angle θ formed by the surface of the glass substrate 2 is closer to a vertical state than about 80°.

Furthermore, in the light-shielding layer 2B near the middle layer 4B, since the carbon concentration in the composition is kept low, the lateral etching rate of this part is the same as the light-shielding layer 2B on the glass substrate 2 side. However, the carbon concentration in the composition of the adjacent intermediate layer 4B is relatively high, and the lateral etching rate is low, so it is not etched. Therefore, the side etching amount of the light-shielding layer 2B in the portion adjacent to the intermediate layer 4B is also reduced. Thereby, as shown in FIG. 4, the angle θ formed by the light shielding patterns 3, 4, 5 and the surface of the glass substrate 2 can be made closer to the vertical state than about 80°.

In this embodiment, the etching rate of the chromium layer on the side of the glass substrate 2 is controlled so as to change in the film thickness direction when viewed from the light-shielding layer 3B and the intermediate layer 4B. Thereby, the generation of skirt-like bottoms on the cross-sectional shapes of the shading patterns 3, 4, and 5 can be suppressed, and a good cross-sectional shape can be obtained.

Specifically, from the perspective of the light shielding layer 3B and the intermediate layer 4B, the concentration of carbon or oxygen, or both carbon and oxygen contained in the chromium layer is controlled in the film thickness direction, so that the upper chromium layer, that is, the intermediate layer 4B The carbon concentration or oxygen concentration is greater than that of the lower side chromium layer, that is, the light-shielding layer 3B. Thereby, it is possible to control the etching rate of the upper chromium layer, that is, the intermediate layer 4B, slower than the etching rate of the lower chromium layer, that is, the light-shielding layer 3B.

By controlling the carbon concentration or oxygen concentration in the chromium film in this way, a cross-sectional shape with fewer skirt-like bottoms can be obtained.

Therefore, in this embodiment, it is possible to form a low sheet resistance that can reduce the effect of electrostatic breakdown even when the thickness of the chromium film is 100 nm or more, and more preferably 200 nm or more. It is possible to prevent the mask substrate 1B from being generated at the bottom of the skirt. As a result, the pattern line width unevenness in the mask 1 can be reduced.

In this embodiment, the intermediate layer 4B is exemplified as a single layer with respect to the chromium film, that is, the light-shielding layer 3B. However, it is not limited to this structure, as long as it is a structure that can simultaneously reduce electrostatic breakdown and prevent the generation of skirt-like bottoms. It can be set as an intermediate layer made up of multiple layers.

In this embodiment, the film forming section S13, S14, and S15 are provided in the film forming chamber S12 in order to form films on the glass substrate 2, but the number of stages may be less than this. The number of film forming parts. In this case, the glass substrate 2 is returned to any film forming part, and the corresponding film can be formed according to different film forming conditions.

[Example]

Hereinafter, embodiments of the present invention will be described.

<Composition measurement>

First, the anti-reflection layer, intermediate layer, and light-shielding layer in the mask substrate of the present invention are subjected to Cr (chromium), N (nitrogen), C (carbon), and O (oxygen) using OJ electron spectroscopy. The composition analysis, the results obtained are shown in Table 1. Furthermore, in this Table 1, layer A represents an anti-reflection layer, layer B represents an intermediate layer, and layer C represents a light-shielding layer.

Similarly, the composition analysis of the anti-reflection layer and the light-shielding layer in the mask substrate without the intermediate layer was carried out using the Ogee electron spectroscopy method, and the obtained results are shown in Table 2. In this Table 2, layer A represents an anti-reflection layer, and layer B represents a light-shielding layer.

It can be seen from these results that in the three-layer structure shown in Table 1, the carbon concentration in layer B (middle layer) is about twice as high as that in layer C (light-shielding layer) and layer A (anti-reflection layer).

<Confirm the bottom of the skirt>

Next, pattern the mask substrate with the three-layer structure of the anti-reflection layer, the intermediate layer, and the light-shielding layer in the present invention, and confirm the production of the skirt-like bottom in the pattern.

The results are shown in Fig. 4. In addition, FIG. 4 shows only the contour lines in order to clarify the SEM (scanning electron microscope) image obtained by taking the cross-section.

In addition, the film thickness of each layer is as follows.

Set as: chromium layer (intermediate layer, light shielding layer) with a film thickness of 200 nm; layer A (anti-reflection layer), 25 nm; layer B (intermediate layer), 150 nm; layer C (light shielding layer), 50 nm.

The chromium layer here means the low-resistance chromium layer after excluding the high-resistance anti-reflection layer, that is, the A layer. In the case of a two-layer structure, it means the film thickness of the B layer. In the case of a three-layer structure, it means the B layer and the The added film thickness of layer C.

Similarly, pattern the mask substrate of the double-layer structure without the intermediate layer, and confirm the production of the skirt-like bottom in the pattern.

The results are shown in Fig. 5.

In addition, the film thickness of each layer is as follows.

Set as: chromium layer (light-shielding layer) with a film thickness of 200 nm; layer A (anti-reflection layer), 25 nm; layer B (light-shielding layer), 200 nm.

Furthermore, the film thickness of the chromium layer was changed and the taper angle θ was measured.

The results are shown in Fig. 6.

From these results, it can be seen that by making a three-layer structure, the taper angle θ of the mask can be increased compared with a two-layer structure. When the film thickness of the chromium layer is 200 nm, the taper angle θ is 45° in the two-layer structure. In contrast, by making the three-layer structure, the taper angle θ can be increased to 80°.

Furthermore, when the film thickness of the chromium layer is 150nm, the film thickness of each layer of the three-layer structure can be set to 25nm for the A layer, 100nm for the B layer, and 50nm for the C layer. In the two-layer structure, it can be set to 25nm for the A layer, The B layer is 150nm.

<Measurement of sheet resistance>

Next, the sheet resistance of the mask substrate with the three-layer structure of the anti-reflection layer, the intermediate layer, and the light-shielding layer in the present invention was measured, and the relationship between the sheet resistance and the film thickness of the chromium layer was confirmed.

Similarly, measure the sheet resistance of a double-layered mask substrate without an intermediate layer, and confirm the relationship between the sheet resistance and the film thickness of the chromium layer.

These results are shown in Figure 7.

It can be seen from these results that in the three-layer structure, since a chromium film with a higher carbon concentration or oxygen concentration is used for the intermediate layer, the sheet resistance increases compared with a double-layer structure mask with the same chromium layer film thickness. When the film thickness of the chromium layer is 150 nm or 200 nm, the sheet resistance is 10 Ω/sq or less.

<Confirmation of Electrostatic Breakdown>

Secondly, for the three-layer structure of the mask substrate formed with the anti-reflection layer, the intermediate layer, and the light-shielding layer in the present invention, the relationship between the measured sheet resistance and the occurrence of electrostatic breakdown was confirmed.

Here, the rate of occurrence of electrostatic breakdown is to charge the photomask formed on the glass substrate, and to confirm the rate of damage of the photomask pattern by electrostatic breakdown by visual observation under a microscope, and evaluate it.

Similarly, for a double-layer mask substrate without an intermediate layer, confirm the relationship between the measured sheet resistance and the occurrence of electrostatic breakdown.

The results are shown in Figure 8.

From these results, it can be seen that even in the three-layer structure, the occurrence of electrostatic breakdown can be suppressed by making the sheet resistance 10 Ω/sq or less.

The result shows that by using a mask substrate with a sheet resistance of 10Ω/sq or less in a 3-layer structure with a higher carbon concentration in the B layer, an antistatic effect with resistance to electrostatic breakdown can be formed even in the cross section of the mask. The shape of the mask has less skirt bottom and less uneven line width.

[Industrial availability]

A photomask and a photomask substrate capable of suppressing electrostatic breakdown can be cited as a practical example of the present invention.

1B‧‧‧Mask base

2‧‧‧Glass substrate (transparent substrate)

3B‧‧‧Shading layer

4B‧‧‧Middle floor

5B‧‧‧Anti-reflective layer

Claims (4)

A photomask base, characterized by comprising: a transparent substrate; a light-shielding layer formed on the surface of the above-mentioned transparent substrate and mainly composed of chromium; an anti-reflection layer, which contains more oxygen than the above-mentioned light-shielding layer; and an intermediate layer Compared with the anti-reflection layer and the light shielding layer, it contains more carbon; and the carbon content in the intermediate layer is set to 14.5atm% or more, and the sheet resistance is set to be less than 10Ω/sq. The photomask substrate of claim 1, wherein the carbon content in the intermediate layer is set to be more than twice that of the light-shielding layer. A photomask, characterized in that it is manufactured from the photomask substrate of claim 1 or 2, and the light-shielding pattern formed by removing the light-transmitting area from the light-shielding layer and the wall surface of the light-transmitting area and the The angle at which the surfaces of the transparent substrates meet is set to 80° or more. A method for manufacturing a photomask substrate, characterized in that it is the method for manufacturing a photomask substrate as claimed in claim 1 or 2, during the film formation of the intermediate layer, and the film formation of the anti-reflection layer and the light-shielding layer Compared with setting the partial pressure of the carbon-containing gas to be higher.

Images