TWI774840B - Mask blank and its manufacturing method, mask and its manufacturing method, exposure method, and device manufacturing method - Google Patents

Abstract

The mask blank of the present invention has a substrate and at least a first layer and a second layer in order from the substrate side, the first layer contains chromium, the second layer contains chromium and oxygen, and the surface of the second layer is The arithmetic mean height is 0.245nm or more.

Description

Mask blank and its manufacturing method, mask and its manufacturing method, exposure method, and device manufacturing method

The present invention relates to a photomask blank, a photomask, an exposure method, and a device manufacturing method.

There is known a mask blank in which a light-shielding layer formed of a chromium-containing material containing chromium and a reflection reducing layer formed of a laminated film formed of a chromic oxide material are laminated on a transparent substrate (Patent Document 1).

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2016-105158

According to the first aspect of the present invention, the photomask blank is a photomask blank having a substrate and at least a first layer and a second layer in this order from the substrate side, wherein the first layer contains chromium, and the second layer contains For chromium and oxygen, the arithmetic mean height of the surface of the second layer is 0.245 nm or more.

According to the second aspect of the present invention, the photomask blank is a photomask blank having a substrate and at least a first layer and a second layer in this order from the substrate side, wherein the first layer contains chromium, and the second layer contains Chromium and oxygen, the difference between the arithmetic mean height of the surface of the second layer and the arithmetic mean height of the surface of the substrate is 0.03 nm or more.

According to the third aspect of the present invention, the photomask is a photomask formed by forming the first layer and the second layer of the photomask blank of the first or second aspect into a predetermined pattern.

According to the fourth aspect of the present invention, the exposure method is to expose the photosensitive substrate coated with the photoresist through the photomask of the third aspect.

According to a fifth aspect of the present invention, a device manufacturing method includes: an exposure step of exposing the photosensitive substrate by the exposure method of the fourth aspect; and a development step of developing the exposed photosensitive substrate .

10: Photomask blank

11: Substrate

12: shading layer

13: Low reflection layer

100: Manufacturing Device

FIG. 1 is a view showing a configuration example of a mask blank according to an embodiment.

FIG. 2 is a schematic diagram showing an example of a manufacturing apparatus that can be used to manufacture a photomask blank.

FIG. 3 is a table showing the measurement results of the photomask blanks of Examples and Comparative Examples.

FIG. 4 is a schematic diagram for explaining the cross-sectional shape of the mask pattern produced by using the mask blank of the embodiment.

FIG. 5 is a conceptual diagram showing a state in which a photosensitive substrate is exposed through a mask.

FIG. 6 is a diagram showing a configuration example of a mask blank of a comparative example.

FIG. 7 is a schematic diagram for explaining the cross-sectional shape of the mask pattern produced using the mask blank of the comparative example.

(Embodiment)

FIG. 1 is a diagram showing a configuration example of a mask blank 10 according to the present embodiment. The mask blank 10 includes a substrate 11. A first layer (hereinafter referred to as a light shielding layer) 12 and a second layer (hereinafter referred to as a low reflection layer) 13 . In the mask blank 10 in the present embodiment, as shown in FIG. 1 , the surface of the low reflection layer 13 has a predetermined level of fine unevenness (a predetermined arithmetic mean height). In the present embodiment, by adjusting the oxygen content (the atomic number concentration of oxygen) of the low-reflection layer 13 by sputtering, a predetermined arithmetic mean height is generated on the surface of the low-reflection layer 13 . Hereinafter, the present embodiment will be described in detail.

A material such as synthetic quartz glass is used for the substrate 11 . In addition, as the material of the substrate 11, what is necessary is just to transmit the exposure light used in the exposure process at the time of element manufacture. The light shielding layer 12 is made of a material containing chromium (Cr), and is formed on the substrate 11 . The light shielding layer 12 is, for example, a CrCN film which is a chromium-based material containing chromium, carbon (C), and nitrogen (N). The light shielding layer 12 has a function of shielding the exposure light used in the exposure step. In addition, the light shielding layer 12 may be constituted by a single film, or may be constituted by laminating a plurality of layers of films.

The low-reflection layer 13 is provided as a material containing chromium and oxygen (O), for example, a CrOCN film made of a chromium-based material containing chromium, oxygen, carbon and nitrogen, which is laminated on the light shielding layer 12 . When using the mask blank 10 to make a mask, a photoresist is coated on the surface of the low reflection layer 13 (the surface on the opposite side to the surface in contact with the light shielding layer 12 ). The low reflection layer 13 has a function of reducing (suppressing) the reflection of the exposure light when a desired pattern is drawn on the formed photoresist layer by the exposure light. Thereby, the shape precision of the pattern drawn by reflection of exposure light is prevented from falling. In addition, when exposing the device substrate through a photomask in which the light-shielding layer 12 and the low-reflection layer 13 are formed into a desired pattern, the surface of the photomask on which the desired pattern is formed becomes the lower surface (the exit side of the exposure light). ) is configured and used. At this time, the exposure light which passed through the mask and reached the substrate for elements may be reflected toward the mask side. In addition, when the reflected exposure light is further reflected from the mask surface and reaches the element substrate, the exposure light is irradiated to areas other than the region of the element substrate to be irradiated with the exposure light, causing poor exposure. However, in this embodiment, since the low reflection layer 13 is formed, the reflection of the exposure light on the mask surface can be reduced, and the exposure light passing through the low reflection layer 13 is absorbed by the light shielding layer 12, so the above-mentioned exposure defects can be suppressed. In addition, the low reflection layer 13 may be formed of a single film, or may be formed by laminating a plurality of films.

In addition, the mask blank 10 can be used as a mask blank for producing display elements such as FPD (Flat Panel Display) and semiconductor elements such as LSI (Large Scale Integration), for example. In order to manufacture a photomask using the photomask blank 10, for example, the procedure described below is performed.

The photoresist layer formed on the low reflection layer 13 of the mask blank 10 is patterned by energy beams such as laser light, electron beam, or ion beam. By developing the patterned photoresist layer, the drawn portion or the non-drawn portion is removed to form a pattern on the photoresist layer. Then, wet etching is performed using the formed pattern as a mask, thereby forming a shape corresponding to the pattern formed in the photoresist layer on the low reflection layer 13 and the light shielding layer 12 . Finally, the photomask is completed by removing the photoresist layer that functions as a part of the mask.

The arithmetic mean height of the low-reflection layer 13 and the interface between the low-reflection layer 13 and the photoresist layer when patterns are formed by wet etching the photoresist layer formed on the surface of the low-reflection layer 13 by the present inventors The dissociation relationship was studied. As a result, it was found that when the surface of the low-reflection layer 13 is set to a predetermined arithmetic mean height, peeling of the interface between the low-reflection layer 13 and the photoresist layer can be suppressed. In addition, the so-called arithmetic mean height in this specification is the value prescribed|regulated by ISO25178. It is presumed that the reason why the peeling at the interface between the low-reflection layer 13 and the photoresist layer can be suppressed is that by setting the surface of the low-reflection layer 13 to a predetermined arithmetic mean height, the low-reflection layer 13 and the photoresist layer The tightness is improved.

As will be described below, when the arithmetic mean height of the surface of the low-reflection layer 13 is greater than or equal to 0.245 nm, the adhesion between the low-reflection layer 13 and the photoresist layer is relatively high, and the mask blank 10 that satisfies this condition can be The phenomenon that the etchant penetrates into the interface between the low reflection layer 13 and the photoresist layer during wet etching is effectively prevented.

In order to make the surface of the low-reflection layer 13 a predetermined arithmetic mean height, when the low-reflection layer 13 is formed by sputtering, for example, the flow rate of oxygen gas introduced into the sputtering chamber is adjusted so that the low-reflection layer 13 contains more than a predetermined amount of formed by oxygen.

An example of the manufacturing method of the mask blank 10 of this embodiment is demonstrated below.

FIG. 2 is a schematic diagram showing an example of a manufacturing apparatus for manufacturing the mask blank 10 of the present embodiment. FIG. 2( a ) is a schematic diagram when the inside of the manufacturing apparatus 100 is observed from the upper surface, and FIG. 2( b ) is a schematic diagram when the internal condition of the manufacturing apparatus 100 is observed from the side. The manufacturing apparatus 100 shown in FIG. 2 is an inline type sputtering apparatus, and includes a chamber 20 for carrying the substrate 11 for producing the mask blank 10, a first sputtering chamber 21, a buffer chamber 22, The second sputtering chamber 23 and the chamber 24 for carrying out the fabricated photomask blank 10 .

The substrate holder 30 is a frame-shaped holder on which the substrate 11 of the photomask blank 10 can be placed, and is placed while supporting the outer edge portion of the substrate 11 . The surface of the substrate 11 is ground and cleaned, and is placed on the substrate holder 30 so that the surface on which the light shielding layer 12 and the low reflection layer 13 are formed becomes the lower side (downward). In the sputtering apparatus 100 , the substrate holder 30 on which the substrate 11 is placed is moved in the direction indicated by the broken line arrow 25 in FIG. 2 while maintaining the state in which the surface of the substrate 11 faces the target as described below. , and the light shielding layer 12 and the low reflection layer 13 are formed on the surface of the substrate 11 .

The chamber 20 for carrying in, the 1st sputtering chamber 21, the buffer chamber 22, the 2nd sputtering chamber 23, and the chamber 24 for carrying out are each partitioned by the shutter which is not shown in figure, respectively. The chamber 20 for carrying in, the first sputtering chamber 21, the buffer chamber 22, the second sputtering chamber 23, and the chamber 24 for carrying out are respectively connected to exhaust devices (not shown) to exhaust the inside of each chamber. gas.

A first target material 41 is arranged inside the first sputtering chamber 21 , and a second target material 42 is arranged inside the second sputtering chamber 23 . A DC power source (not shown) is provided in the first sputtering chamber 21 and the second sputtering chamber 23, respectively, and power is supplied to the first target material 41 and the second target material 42, respectively.

The first sputtering chamber 21 is provided with a first gas inflow port 31 for introducing a sputtering gas into the first sputtering chamber 21 . The first target 41 is a sputtering target for forming the light shielding layer 12 , and is formed of a material containing chromium. Specifically, the first target 41 is formed of a material selected from the group consisting of chromium, chromium oxide, chromium nitride, chromium carbide, and the like. For example, in order to form a CrCN film as the light shielding layer 12 , a mixed gas of a gas containing nitrogen and carbon and an inert gas (argon or the like) is introduced through the first gas inflow port 31 .

The second sputtering chamber 23 is provided with a second gas inflow port 32 for introducing a sputtering gas into the second sputtering chamber 23 . The second target 42 is a sputtering target for forming the low-reflection layer 13, and is formed of a material containing chromium (chromium, etc.). For example, in order to form a CrOCN film as the low reflection layer 13 , a mixed gas of a gas containing oxygen, nitrogen, and carbon and an inert gas is introduced through the second gas inflow port 32 .

When the substrate 11 is transferred to the first sputtering chamber 21 , the light shielding layer 12 (CrCN film) is formed on the surface of the substrate 11 by sputtering in the first sputtering chamber 21 . The substrate 11 with the light shielding layer 12 formed thereon is transferred to the second sputtering chamber 23 via the buffer chamber 22 . In the second sputtering chamber 23, the low reflection layer 13 (CrOCN film) is formed on the surface of the light shielding layer 12 by sputtering. The substrate 11 on which the light-shielding layer 12 and the low-reflection layer 13 are formed is conveyed to the chamber 24 for carrying out. As a result, the light shielding layer 12 and the low reflection layer 13 are sequentially formed on the surface of the substrate 11 , thereby producing the mask blank 10 .

Furthermore, the materials of the first and second targets 41 and 42 and the types of gases introduced from the first and second gas inflow ports 31 and 32 may be appropriately selected according to the materials or compositions of the light shielding layer 12 or the low reflection layer 13 . choose. In addition, as the method of sputtering, any method such as DC sputtering, RF sputtering, and ion beam sputtering can be used.

As described above, in this embodiment, in order to make the surface of the low-reflection layer 13 a predetermined arithmetic mean height, when the low-reflection layer 13 is formed by sputtering, the sputtering introduced into the second sputtering chamber 23 is adjusted. The low-reflection layer 13 is formed so that a predetermined amount or more of oxygen is contained by the amount of oxygen contained in the gas. Thereby, the arithmetic mean height of the low reflection layer 13 is adjusted. By setting the surface of the low-reflection layer 13 to a predetermined arithmetic mean height, the adhesion between the low-reflection layer 13 and the photoresist can be improved, and when wet etching the mask blank 10, the etchant can be prevented from infiltrating to a low level. The interface between the reflective layer 13 and the photoresist layer. As a result, when a photomask is manufactured using the photomask blank 10 of this embodiment, a pattern can be formed with high precision. Therefore, the yield of the manufacturing step of the photomask can be improved.

In addition, by performing the exposure step using the photomask produced from the photomask blank 10 of the present embodiment, a high-definition element can be produced. In addition, it is possible to reduce the defect of the circuit pattern generated in the exposure step In this case, the productivity of the manufacturing steps of the device can be improved.

According to the above-mentioned embodiment, the following effects can be obtained.

(1) The mask blank 10 is a mask blank 10 having a substrate 11 and at least a light shielding layer 12 and a low reflection layer 13 in this order from the substrate side. The light shielding layer 12 contains chromium, the low reflection layer 13 contains chromium and oxygen, and the arithmetic mean height of the surface of the low reflection layer 13 is 0.245 nm or more. When the arithmetic mean height of the surface of the low reflection layer 13 is 0.245 nm or more, the adhesion between the low reflection layer 13 and the photoresist layer becomes high. Thereby, the phenomenon that the etching solution penetrates into the interface of the low reflection layer 13 and the photoresist layer in wet etching can be suppressed.

(2) When a photomask is manufactured using the photomask blank 10 of the present embodiment, a pattern can be formed with high accuracy. Therefore, the yield of the manufacturing step of the photomask can be improved. In addition, the low-reflection layer 13 or the light-shielding layer 12 at the edge of the pattern can be prevented from having an inclined surface formed by the penetration of the etching solution, and the function of reducing the reflection of the low-reflection layer 13 or the light-shielding function of the light-shielding layer 12 can be prevented from being reduced. the reduction.

(Example 1)

First, a transparent glass substrate 11 made of synthetic silica glass is prepared. Using the in-line sputtering apparatus 100 shown in FIG. 2 , the light shielding layer 12 and the low reflection layer 13 are sequentially formed on the surface of the glass substrate 11 . Hereinafter, the manufacturing method of each of the light shielding layer 12 and the low reflection layer 13 will be described in more detail.

A mixed gas of argon (Ar), nitrogen (N ₂ ) and methane (CH ₄ ) was introduced into the first sputtering chamber 21 (the flow rates of each of Ar, N ₂ , and CH ₄ were set to 172.8 sccm, 60 sccm, 7.2 seem, the pressure was set to 0.6 Pa) as the sputtering gas. While introducing sputtering gas, sputtering was performed with the power of the DC power supply of the first sputtering chamber 21 set to 8.5 kW, and the light shielding layer 12 made of CrCN was formed on the substrate 11 with a thickness of 70 nm.

Next, a mixed gas of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and oxygen (O ₂ ) (a mixture of Ar, CO ₂ , N ₂ , and O ₂ ) is introduced into the second sputtering chamber 23 . The flow rate of each gas was set to 240 sccm, 45 sccm, 120 sccm, and 6 sccm, respectively, and the pressure was set to 0.3 Pa) as the sputtering gas. In addition, sputtering was performed by setting the power of the DC power supply of the second sputtering chamber 23 to 8.5 kW, and the low reflection layer 13 made of CrOCN was formed on the surface of the light shielding layer 12 with a thickness of 30 nm.

The arithmetic mean of the surface of the low-reflection layer 13 in the range of 86.9 μm×86.9 μm was obtained by measuring with a coherent scanning interferometer (NewView 8000 manufactured by Zygo) in the mask blank 10 produced in the above-mentioned procedure. Height Sa. In addition, the atomic number concentration of oxygen in the depth direction of the low reflection layer 13 was measured by an X-ray photoelectron spectrometer (Quantera II manufactured by PHI Corporation). The results of these measurements are shown in the table of FIG. 3 .

The produced photomask blank 10 was subjected to UV cleaning for 10 minutes, followed by rotary cleaning (megasonic cleaning, alkaline cleaning, brush cleaning, rinsing, and spin drying) for 15 minutes. The coater forms a photoresist layer on the surface of the low reflection layer 13 . Then, using a mask alignment exposure machine, after exposure with a pattern of lines and spaces with a pitch of 2 μm, development is performed to partially remove the photoresist layer to form a photoresist pattern. Using the photoresist pattern as a mask, the photomask blank 10 with the photoresist pattern formed thereon is immersed in an etching solution using ceric ammonium nitrate as a base material to perform wet etching, thereby forming the low reflection layer 13 and the light shielding layer 12. pattern.

After the pattern is formed, it is cut, and the cross-sectional shape of the pattern is observed with a scanning electron microscope (SEM) to confirm whether the etchant has penetrated into the interface between the photoresist layer and the low-reflection layer 13 according to the cross-sectional shape of the pattern. The results are shown in the table of FIG. 3 .

(Example 2)

A substrate 11 made of synthetic silica glass was prepared in the same manner as the substrate 11 used in Example 1. The light shielding layer 12 was formed under the same conditions as in Example 1. Then, when forming the low reflection layer 13, in Example 1, the flow rate of the oxygen gas (O ₂ ) introduced into the second sputtering chamber 23 was set to 6 sccm, but in this example, the oxygen gas (O ₂ ) The low reflection layer 13 was formed under the same conditions as in Example 1, except that the flow rate was set to 18 sccm. The same items as in Example 1 were measured. The measurement results are shown in the table of FIG. 3 .

(Example 3)

A substrate 11 made of synthetic silica glass was prepared in the same manner as the substrate 11 used in Example 1. The light shielding layer 12 was formed under the same conditions as in Example 1. Next, when the low reflection layer 13 was formed, the flow rate of the oxygen gas (O ₂ ) introduced into the second sputtering chamber 23 was set to 30 sccm. The low reflection layer 13 was formed under the same conditions as in Example 1 except for the flow rate of oxygen. Then, the same items as in Example 1 were measured. The measurement results are shown in the table of FIG. 3 .

(Example 4)

A substrate 11 made of synthetic silica glass was prepared in the same manner as the substrate 11 used in Example 1. The light shielding layer 12 was formed under the same conditions as in Example 1. Next, when forming the low-reflection layer 13 , the low-reflection layer 13 was formed under the same conditions as in Example 1, except that the flow rate of oxygen gas (O ₂ ) introduced into the second sputtering chamber 23 was 48 sccm. The same items as in Example 1 were measured. The measurement results are shown in the table of FIG. 3 .

(Comparative Example 1)

A substrate 51 made of synthetic silica glass similar to the substrate 11 used in Example 1 was prepared. The light shielding layer 52 was formed under the same conditions as in Example 1. Next, when forming the low-reflection layer 53 , the low-reflection layer 53 was formed under the same conditions as in Example 1, except that the amount of oxygen (O ₂ ) introduced into the second sputtering chamber 23 was set to 0 sccm. That is, in Comparative Example 1, oxygen gas was not introduced into the second sputtering chamber 23 when the low reflection layer 53 was formed. FIG. 6 is a schematic diagram showing the structure of the produced photomask blank 50 . In the photomask blank 50 of Comparative Example 1, a light shielding layer 52 and a low reflection layer 53 are sequentially formed on the surface of the substrate 51 . Then, the same items as in Example 1 were measured. The measurement results are shown in the table of FIG. 3 .

In the table shown in FIG. 3 , about Example 1, Example 2, Example 3, Example 4, and Comparative Example 1, the oxygen atomic number concentration, distance and distance of the low reflection layer near the surface (surface layer) are shown. The concentration of oxygen atoms at the position of the surface depth of 5 nm of the low reflection layer, the arithmetic mean height Sa1 of the surface of the low reflection layer, the difference between the arithmetic mean height Sa1 of the low reflection layer and the arithmetic mean height Sa2 of the substrate (the value of Sa1 minus Sa2 The value obtained from the value), and the presence or absence of penetration of the etching solution. According to Figure 3, it can be seen that Examples 1 to 4 In contrast, the arithmetic mean height of the surface of the low-reflection layer in Comparative Example 1 was 0.242 nm, which was smaller than that of Examples 1-4. In addition, it can be seen that the oxygen atomic number concentration at a position 5 nm deep from the surface (a position away from the surface) is lower than the oxygen atomic number concentration in the vicinity of the surface (surface layer).

FIG. 4 is a diagram schematically showing a state in which the mask blank 10 produced in Examples 1 to 4 is wet-etched, then cut, and the pattern cross section is observed by a scanning electron microscope (SEM). In the mask blank 10 , a pattern corresponding to the mask formed on the photoresist layer 15 is formed on the low reflection layer 13 and the light shielding layer 12 by wet etching. As shown in FIG. 4 , after wet etching the mask blanks 10 produced in Examples 1 to 4, no inclined surface formed by the infiltration of the etching solution was observed at the edge of the pattern, and it was confirmed that the edge of the pattern was formed by It is formed substantially perpendicular to the surface of the substrate 11 . That is, in Examples 1 to 4, when the low-reflection layer 13 was formed by sputtering, the surface of the low-reflection layer 13 was set to a predetermined arithmetic mean height by adjusting the flow rate of oxygen gas introduced into the sputtering chamber. . It is considered that the adhesion between the photoresist and the low reflection layer 13 is thereby improved.

FIG. 7 is a diagram schematically showing a state in which the mask blank 50 produced in Comparative Example 1 was wet-etched, then cut, and the pattern cross section was observed with a scanning electron microscope (SEM). As shown in FIG. 7 , after wet etching, the photomask blank 50 produced by Comparative Example 1 was formed at the interface between the photoresist layer 55 and the low reflection layer 53 at the edge of the pattern due to the penetration of the etching solution. the inclined surface.

In such a mask for generating an inclined surface, since the thickness of the low-reflection layer becomes smaller in the region where the inclined surface is generated, the function of reducing the reflection of exposure light is reduced. As a result, when a circuit pattern is formed on the substrate for elements using such a mask, the accuracy of the circuit pattern formed on the substrate for elements falls. Furthermore, when the penetration of the etching solution is larger, a larger inclined surface such as spanning the low-reflection layer and the light-shielding layer is generated. In such a photomask, not only the function of reducing the reflection of the exposure light by the low-reflection layer is reduced, but also the light-shielding performance of the light-shielding layer against the exposure light is also reduced. Therefore, such photomasks are not suitable for device fabrication.

From the above results, when oxygen gas is introduced into the sputtering chamber during the formation of the low-reflection layer 13, the value represented by the arithmetic mean height Sa1 of the surface of the low-reflection layer becomes larger. By setting the arithmetic mean height Sa1 to a predetermined size , the adhesion between the photoresist layer and the low reflection layer 13 can reach a sufficient level. It is considered that if the arithmetic mean height Sa1 of the surface of the low reflection layer 13 is 0.245 nm or more, the adhesion between the photoresist layer and the low reflection layer 13 is sufficiently large, and it is considered that the etchant can be prevented from infiltrating into these interfaces. In addition, the value of the arithmetic mean height Sa1 of the surface of the low reflection layer 13 is not particularly limited as long as the desired antireflection performance can be obtained, for example, the upper limit can be set to 1.0 nm.

According to the measurement result of FIG. 3 , the low-reflection layer 13 preferably has an oxygen atomic number concentration of 44% or more in the surface layer. In addition, the low-reflection layer 13 preferably has an oxygen atomic number concentration of 35% or more in a depth of 5 nm from the surface. Thereby, the adhesiveness of the photoresist layer and the low reflection layer 13 can be improved, and it can suppress that the etching liquid penetrates into these interfaces.

In addition, the surface of the substrate 11 of the mask blank 10 is usually ground. On the other hand, since the low-reflection layer 13 is formed by sputtering, the short-period component of the arithmetic mean height of the substrate 11 is smaller than that of the low-reflection layer 13 . In addition, the low-reflection layer 13, not the substrate 11, is in direct contact with the photoresist, and it is considered that the short-period component of the arithmetic mean height of the low-reflection layer 13 functions effectively by the adhesion to the photoresist. Therefore, the difference between the arithmetic mean height Sa1 of the surface of the low reflection layer 13 and the arithmetic mean height Sa2 of the surface of the substrate 11 (0.217 nm in the present embodiment and the comparative example) is preferably 0.03 nm or more. In addition, from the viewpoint of the pattern edge roughness after etching, the upper limit of the difference between the arithmetic mean height Sa1 of the surface of the low reflection layer 13 and the arithmetic mean height Sa2 of the surface of the substrate 11 may be set to 1.0 nm.

The following modifications are also within the scope of the present invention, and one or several modified examples may be combined with the above-described embodiments.

(Variation 1)

In the above-described embodiment, when the low reflection layer 13 is formed by sputtering, the introduction into the sputtering chamber is adjusted. The flow rate of oxygen is determined, and the arithmetic mean height of the low-reflection layer 13 is set to a predetermined range. However, instead of adjusting the flow rate of oxygen gas introduced into the sputtering chamber, or on this basis, after the low-reflection layer 13 is formed, its surface can be set to a predetermined arithmetic mean height by dry etching or wet etching. Thereby, the adhesiveness of the photoresist and the low reflection layer 13 can be improved.

(Variation 2)

The photomask blank 10 described in the above-described embodiment and modification examples can be used as a photomask blank for producing photomasks for display device production, semiconductor production, and printed circuit board production. Furthermore, in the case of producing a mask blank of a mask for manufacturing a display device, a substrate having a size of 520 mm×800 mm or more can also be used as the substrate 11 . In addition, the thickness of the substrate 11 may be 8˜21 mm.

Next, as an application example of the photomask produced by using the photomask blank 10 produced in Examples 1 to 4, a photolithography step in semiconductor manufacturing or liquid crystal panel production will be described with reference to FIG. 5 . The photomask 513 produced by the photomask blank 10 produced in Examples 1 to 4 was used in the exposure apparatus 500 . In addition, a photosensitive substrate 515 coated with a photoresist is also arranged in the exposure apparatus 500 .

The exposure apparatus 500 includes a light source LS, an illumination optical system 502, a mask support table 503 for holding a mask 513, a projection optical system 504, an exposure object support table 505 for holding an object to be exposed, that is, a photosensitive substrate 515, and an exposure object support table 505. A drive mechanism 506 for moving the object support table 505 in a horizontal plane. The exposure light emitted from the light source LS of the exposure apparatus 500 is incident on the illumination optical system 502 , adjusted to a predetermined light beam, and irradiated to the mask 513 held by the mask support table 503 . The light passing through the mask 513 has an image of the element pattern drawn on the mask 513 , and is irradiated to a predetermined position of the photosensitive substrate 515 held by the exposure object support table 505 through the projection optical system 504 . Thereby, the image of the element pattern of the photomask 513 is imagewise exposed to the photosensitive substrate 515 such as a semiconductor wafer or a liquid crystal panel at a predetermined magnification.

Various embodiments and modified examples have been described above, but the present invention is not limited to these contents. Other aspects that can be conceived within the scope of the technical idea of the present invention are also included in the scope of the present invention.

The disclosures of the priority basic applications below are incorporated herein by reference.

Japanese Patent Application No. 2017 No. 171997 (filed on September 7, 2017)

10: Photomask blank

11: Substrate

12: shading layer

13: Low reflection layer

Claims (22)

A photomask blank for forming a photomask with a predetermined pattern by wet etching, comprising: a substrate, a first layer on the substrate, and a second layer on the first layer, and The arithmetic mean height of the surface of the second layer is 0.245 nm or more. The photomask blank of claim 1, wherein the difference between the arithmetic mean height of the surface of the second layer and the arithmetic mean height of the surface of the substrate is 0.03 nm or more. According to the photomask blank of claim 1 or 2, the second layer is a layer containing chromium (Cr) and oxygen (O). According to the photomask blank of claim 1 or 2, the first layer is a layer containing chromium (Cr). According to the photomask blank of claim 3, the second layer is a layer composed of CrOCN or a material with more oxygen in CrOCN than the stoichiometric ratio. According to the photomask blank of claim 3, wherein the oxygen atomic concentration of the second layer in the surface layer is above 44%. According to the mask blank of claim 6, the oxygen atomic concentration of the surface layer of the second layer is higher than that of oxygen in the depth of 5 nm from the surface of the surface of the second layer that is not in contact with the first layer. Atomic number concentration. The photomask blank of claim 3, wherein the number of oxygen atoms in the depth of 5 nm from the surface of the surface of the second layer that is not in contact with the first layer The concentration is above 35%. According to the photomask blank of claim 1 or 2, the size of the above-mentioned substrate is 520mm×800mm or more. According to the photomask blank of claim 1 or 2, the above-mentioned substrate is made of quartz glass. A photomask formed by forming the first layer and the second layer of the photomask blank of any one of claims 1 to 10 into a predetermined pattern shape. An exposure method, which is to expose a photosensitive substrate coated with a photoresist through the photomask of the 11th patent application scope. A device manufacturing method comprising: an exposure step of exposing the photosensitive substrate by the exposure method of claim 12; and a development step of developing the exposed photosensitive substrate. A method for manufacturing a photomask blank, comprising: a first-layer film-forming step of forming a first layer on a substrate; and a second-layer film-forming step of forming a second layer on the first layer, and Wet etching or dry etching is performed on the surface of the second layer to form the second layer with an arithmetic average height of 0.245 nm or more. A method for manufacturing a photomask blank, comprising: a first-layer film-forming step of forming a first layer on a substrate; and a second-layer film-forming step of forming a second layer on the first layer; In the step of forming the second layer, the second layer is formed with an oxygen flow rate of 6 sccm or more and 48 sccm or less, and the second layer having an arithmetic mean height of 0.245 nm or more is formed on the second layer. For example, the manufacturing method of the photomask blank according to the 14th or 15th item of the patent application scope, wherein In the above-mentioned second-layer film forming step, the above-mentioned second layer containing chromium (Cr) and oxygen (O) is formed into a film. The method for producing a mask blank according to claim 14 or 15 of the claimed scope, wherein in the first layer film forming step, the first layer containing chromium (Cr) is formed into a film. According to the method for manufacturing a mask blank according to claim 14 or 15 of the claimed scope, wherein in the film forming step of the second layer, the difference between the arithmetic mean height of the surface of the second layer and the arithmetic mean height of the surface of the substrate is: The above-mentioned second layer is formed in a manner of 0.03 nm or more. The method for manufacturing a mask blank according to claim 14 or 15 of the claimed scope, wherein the mask blank is used to form a mask with a predetermined pattern by wet etching. A method for manufacturing a photomask, comprising: a pattern forming step, wherein a predetermined pattern is formed by wet etching in the photomask blank of any one of the claims 14 to 19 of the patent application scope. An exposure method for exposing a photosensitive substrate coated with a photoresist through a photomask manufactured by the method for manufacturing a photomask of the 20th patent application scope. A device manufacturing method comprising: an exposure step of exposing the photosensitive substrate by the exposure method of claim 21; and a development step of developing the exposed photosensitive substrate.

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