WO2020054131A1

WO2020054131A1 - Phase shift mask blank, phase shift mask, light exposure method and method for producing device

Info

Publication number: WO2020054131A1
Application number: PCT/JP2019/019862
Authority: WO
Inventors: 隆仁小澤; 庸平寳田; 賢利林; 高史八神
Original assignee: 株式会社ニコン
Priority date: 2018-09-14
Filing date: 2019-05-20
Publication date: 2020-03-19
Also published as: TWI818992B; KR20210032534A; JP7151774B2; TW202011108A; JPWO2020054131A1; CN112689796A; KR102582203B1

Abstract

This phase shift mask blank comprises a substrate and a phase shift layer that is formed on the substrate; the phase shift layer contains chromium and oxygen; and the surface of the phase shift layer has an arithmetic mean height of 0.38 nm or more.

Description

Phase shift mask blank, phase shift mask, exposure method, and device manufacturing method

The present invention relates to a phase shift mask blank, a phase shift mask, an exposure method, and a device manufacturing method.

位相 A phase shift mask in which a phase shift layer made of chromium oxynitride is formed on a transparent substrate is known (Patent Document 1). Conventionally, it has been desired to improve the quality of a phase shift mask.

Japanese Patent Application Laid-Open No. 2011-013283

According to a first aspect of the present invention, a phase shift mask blank is a phase shift mask blank having a substrate and a phase shift layer formed on the substrate, wherein the phase shift layer comprises chromium and oxygen. And the value of the arithmetic average height of the surface of the phase shift layer is 0.38 nm or more.
According to a second aspect of the present invention, a phase shift mask blank is a phase shift mask blank having a substrate and a phase shift layer formed on the substrate, wherein the phase shift layer comprises chromium and oxygen. The value of the arithmetic average height of the surface of the phase shift layer is 0.04 nm or more larger than the value of the arithmetic average height of the surface of the substrate.
According to a third aspect of the present invention, a phase shift mask is a phase shift mask of the phase shift mask blank according to the first or second aspect, wherein the phase shift layer is formed in a predetermined pattern.
According to a fourth aspect of the present invention, an exposure method exposes a photosensitive substrate coated with a photoresist through a phase shift mask according to the third aspect.
According to a fifth aspect of the present invention, a device manufacturing method includes: an exposing step of exposing the photosensitive substrate by the exposing method according to the fourth aspect; and a developing step of developing the exposed photosensitive substrate. Have.

FIG. 3 is a diagram illustrating a configuration example of a phase shift mask blank according to the embodiment. It is a schematic diagram which shows an example of the manufacturing apparatus used for manufacturing a phase shift mask blank. 9 is a table showing measurement results for phase shift mask blanks according to examples and comparative examples. FIG. 4 is a schematic diagram illustrating a cross section of a mask pattern formed using the phase shift mask blanks according to the example. FIG. 4 is a conceptual diagram illustrating a state in which a photosensitive substrate is exposed through a phase shift mask. FIG. 9 is a diagram illustrating a configuration example of a phase shift mask blank according to a comparative example. FIG. 9 is a schematic diagram illustrating a cross section of a mask pattern formed using a phase shift mask blank according to a comparative example.

(Embodiment)
FIG. 1 is a diagram illustrating a configuration example of a phase shift mask blank 10 according to the present embodiment. The phase shift mask blank 10 includes a substrate 11 and a phase shift layer 12. In the present embodiment, the phase shift layer 12 is formed on the surface of the substrate 11 by sputtering. At this time, by setting the oxygen content (oxygen atom concentration) in the phase shift layer 12 according to the sputtering conditions, the surface of the phase shift layer 12 has a predetermined level (a predetermined arithmetic average height) as shown in FIG. ) Is formed.
Hereinafter, the phase shift mask blanks 10 according to the present embodiment will be described in more detail.

合成 As a material of the substrate 11, for example, synthetic quartz glass is used. The material of the substrate 11 is not limited to synthetic quartz glass. The phase shift mask is used when manufacturing a display device such as an FPD (Flat Panel Display) or a semiconductor device such as an LSI (Large Scale Integration). The substrate 11 may be any substrate that can sufficiently transmit exposure light in an exposure step of exposing a substrate to be exposed such as a wafer using a phase shift mask.

(4) The phase shift layer 12 is formed on the surface of the substrate 11 as a film made of a material containing chromium (Cr) and oxygen (O). The phase shift layer 12 according to the present embodiment is composed of a film made of CrOCN. A desired pattern is formed on the phase shift layer 12 to form a phase shift mask. This pattern functions as a phase shifter that locally changes the phase of exposure light emitted in the exposure step.

When exposing a device substrate with exposure light via a phase shift mask having a phase shift layer 12 formed in a desired thickness and a desired pattern, light transmitted through a portion where the phase shift layer 12 exists and phase shift layer 12 A phase difference (a phase shift amount) of approximately 180 ° is generated with light transmitted through a portion where no exists. Thereby, the intensity of the exposure light irradiated to the area other than the exposure pattern area is suppressed to be low, and the contrast of the exposure pattern is improved. As a result, the defective rate in the exposure step can be reduced.

In the above description, it is described that the thickness (film thickness) of the phase shift layer 12 is set so that a phase shift amount of approximately 180 ° occurs in the phase of the exposure light. However, the phase shift amount of the exposure light is not limited to 180 ° as long as the desired contrast is obtained in the exposure step. Note that the phase shift layer 12 may be formed of a single film, or may be formed by stacking a plurality of films.

位相 Phase shift mask A phase shift mask formed by forming a desired pattern on the phase shift layer 12 of the blank 10 is prepared, for example, by the procedure described below.

フォト A photoresist is applied on the surface of the phase shift layer 12 to form a photoresist layer. A pattern is drawn by irradiating the formed photoresist layer with an energy beam such as a laser beam, an electron beam, or an ion beam. By developing the photoresist layer on which the pattern is drawn, a drawn portion or a non-drawn portion is removed, and a pattern is formed on the photoresist layer. The phase shift layer 12 is wet-etched using the patterned photoresist layer as a mask. By this wet etching, a shape corresponding to the pattern formed on the photoresist layer is formed (transferred) on the phase shift layer 12. The phase shift mask is completed by removing the photoresist layer.

The present inventors examined the correlation between the arithmetic average height of the surface of the phase shift layer 12 and the oxygen atom concentration of the phase shift layer 12, and further patterned the photoresist layer formed on the phase shift layer 12. The state of the interface between the phase shift layer 12 and the photoresist layer at that time was examined. As a result, the following findings were obtained. The arithmetic mean height in this specification is defined in ISO25178.
(1) When the arithmetic average height of the surface of the phase shift layer 12 is larger than a predetermined value, for example, 0.38 nm or more, the present inventors use such a phase shift mask blank to perform phase shift. In the step of forming the pattern of the layer 12, it has been found that the etchant does not permeate at the interface between the phase shift layer 12 and the photoresist layer.

When the arithmetic average height of the surface of the phase shift layer 12 is larger than a predetermined value, the infiltration of the etching solution at the interface between the phase shift layer 12 and the photoresist layer can be suppressed by It is estimated that moderate roughness (irregularity) is formed, and due to this roughness, the adhesion between the photoresist layer and the phase shift layer 12 becomes high enough to suppress the penetration of the etching solution. it can.

(2) When the difference between the arithmetic average height of the surface of the phase shift layer 12 and the arithmetic average height of the surface of the substrate 11 is larger than a predetermined value, for example, 0.04 nm or more, such a phase shift mask blank is used. It has been found that in the step of forming a pattern of the phase shift layer 12 by using the same, the etchant does not permeate at the interface between the phase shift layer 12 and the photoresist layer.

(3) It has been found that roughness (irregularities) having a predetermined arithmetic average height can be generated on the surface of the phase shift layer 12 as follows. When the phase shift layer 12 is formed by sputtering, the flow rate of oxygen introduced into the sputtering chamber is adjusted so that the phase shift layer 12 contains a predetermined amount or more of oxygen. It was found that the phase shift layer 12 having the surface was formed. That is, the present inventors have found that there is a correlation between the arithmetic average height of the concavo-convex pattern on the surface of the phase shift layer 12 and the oxygen atom number concentration or concentration distribution near the surface of the phase shift layer 12. .

(4) When the oxygen atom number concentration on the surface of the phase shift layer 12 formed on the phase shift mask blank 10 is higher than a predetermined value, the present inventors provide an interface between the phase shift layer 12 and the photoresist layer. It was found that the etchant did not seep into the substrate.

As described in the above (3), in the phase shift layer 12 in which the oxygen atom number concentration on the surface of the phase shift layer 12 is larger than a predetermined value, the arithmetic mean height of the surface is the predetermined value (for example, 0.38 nm). ), And thus have an appropriate roughness (irregularities). When a photoresist layer is formed on the surface of such a phase shift layer 12, the adhesion between the phase shift layer 12 and the photoresist layer is high, so that the phase shift layer 12 and the photoresist layer are not wetted during wet etching. It is considered that the etchant does not seep into the interface of the substrate.

(5) When the oxygen atom number concentration inside the phase shift layer 12 formed on the phase shift mask blank 10 decreases in the depth direction from the surface of the phase shift layer 12, the phase shift layer 12 and the photoresist layer It was found that the etchant did not penetrate into the interface of. As an example in which the oxygen atom number concentration inside the phase shift layer 12 decreases in the depth direction from the surface of the phase shift layer 12, for example, the oxygen atom number concentration at a position 85 nm deep from the surface of the phase shift layer 12 is exemplified. In this case, the ratio of the oxygen atom number concentration at a position at a depth of 1.25 nm from the surface of the phase shift layer 12 to 1.59 is 1.59 or more.
Hereinafter, an example of a method for manufacturing the phase shift mask blank 10 according to the present embodiment will be described.

(Phase shift mask blank manufacturing method)
FIG. 2 is a schematic diagram illustrating an example of a manufacturing apparatus used to form the phase shift layer 12 when manufacturing the phase shift mask blank 10 according to the present embodiment. FIG. 2A is a schematic diagram when the inside of the manufacturing apparatus 100 is viewed from above, and FIG. 2B is a schematic diagram when the inside of the manufacturing apparatus 100 is viewed from the side. The manufacturing apparatus 100 shown in FIG. 2 is an in-line type sputtering apparatus, in which a chamber 20 for loading a substrate 11 for forming a phase shift layer 12, a sputtering chamber 21, and a phase shift layer 12 are formed. And a chamber 22 for carrying out the substrate 11. In the sputtering chamber 21, a target 41 for forming the phase shift layer 12 is arranged.

The substrate tray 30 is a frame-shaped tray on which the substrate 11 for forming the phase shift layer 12 can be placed, and the outer edge portion of the substrate 11 is supported and placed. The substrate 11 is placed on the substrate tray 30 such that the surface of the substrate 11 is polished and cleaned, and the surface on which the phase shift layer 12 is formed faces downward (downward). In the sputtering apparatus 100, as described later, while maintaining the state where the surface of the substrate 11 faces the target 41, while moving the substrate tray 30 on which the substrate 11 is placed in the direction indicated by the dotted arrow 25 in FIG. The phase shift layer 12 is formed on the surface of the substrate 11.

A gate valve (not shown) is provided between each of the carry-in chamber 20, the sputtering chamber 21, and the carry-out chamber 22, and the respective chambers are communicated and shut off by opening and closing the gate valve. The carry-in chamber 20, the sputtering chamber 21, and the carry-out chamber 22 are each connected to an exhaust device (not shown), and the inside of each chamber is exhausted.
In addition, between each gate valve and the target 41, a sufficient space for holding the substrate tray 30 before and after film formation or a separate waiting chamber is provided (not shown).

ターゲット As described above, the target 41 is provided inside the sputtering chamber 21. The target 41 is a sputtering target for forming the phase shift layer 12, and is formed of a material containing chromium (Cr). Specifically, the material of the target 41 is selected from at least one of chromium, chromium oxide, chromium nitride, chromium carbide, and the like. In the present embodiment, chromium is selected for the target 41. Power is supplied to the target 41 of the sputtering chamber 21 from a DC power supply (not shown).

The sputtering chamber 21 is provided with a first gas inlet 31 and a second gas inlet 32 for introducing a gas for sputtering into the sputtering chamber 21. The first gas inlet 31 is arranged on the side close to the loading chamber 20, that is, on the upstream side (upstream side) with respect to the traveling direction of the substrate tray 30 indicated by the dotted arrow 25. On the other hand, the second gas inlet 32 is disposed on the side closer to the unloading chamber 22, that is, on the downstream side (downstream side) with respect to the traveling direction of the substrate tray 30.

In the present embodiment, a CrOCN film is formed as the phase shift layer 12. For this purpose, a gas containing carbon such as nitrogen gas and carbon dioxide and an inert gas (in this embodiment, argon gas is used) are supplied to the sputtering chamber 21 through the first gas inlet 31. A mixed gas is introduced. In addition, oxygen gas is introduced through the second gas inlet 32.

(4) The substrate 11 is transferred from the loading chamber 20 to the sputtering chamber 21 and sputtering is started. At that time, nitrogen gas, carbon-containing gas, and inert gas are introduced from the first gas inlet 31, and therefore, the side closer to the first gas inlet 31 in the sputtering chamber 21, that is, On the side where sputtering of the substrate 11 is started, the concentrations of these gases are relatively high. On the other hand, since the oxygen gas is introduced from the second gas inlet 32, the oxygen concentration on the side close to the second gas inlet 32 in the sputtering chamber 21, that is, on the side where the sputtering of the substrate 11 is finished. Is relatively high. Therefore, in the formed CrOCN film, as the substrate 11 moves to the right and sputtering proceeds, that is, as the film thickness increases, the oxygen atom number concentration increases. As a result, the side closer to the surface of the phase shift layer 12 (the last deposited side) contains a relatively large amount of oxygen, while the side closer to the substrate (the initially deposited side) contains less oxygen. Less. On the surface of the phase shift layer 12 thus formed, a roughness (concavity and convexity) having a predetermined arithmetic average height is formed. The surface roughness (arithmetic mean height) of the phase shift layer 12 can be controlled by adjusting the flow rate of each gas introduced from the first gas inlet 31 and the second gas inlet 32.

基板 The substrate 11 on which the phase shift layer 12 is formed is transferred to the unloading chamber 22. Thus, the phase shift layer 12 is formed on the surface of the substrate 11, and the phase shift mask blanks 10 are manufactured.

Note that the material of the target 41 and the type of gas introduced from the first gas inlet 31 and the second gas inlet 32, respectively, are appropriately selected according to the material and composition of the phase shift layer 12. Good. Further, as a sputtering method, any method such as DC sputtering and RF sputtering may be used.

As described above, in the present embodiment, when the phase shift layer 12 is formed by sputtering, the flow rate (particularly, the oxygen flow rate) of each gas introduced into the sputtering chamber 21 is adjusted. Thereby, the number of oxygen atoms contained in the phase shift layer 12 is adjusted, and the roughness (arithmetic average height) of the surface of the phase shift layer 12 is adjusted. Thereby, the adhesion between the photoresist layer and the phase shift layer 12 can be sufficiently increased, and the infiltration of the etching solution into the interface between the phase shift layer 12 and the photoresist layer can be prevented. Further, by manufacturing a phase shift mask using the phase shift mask blanks 10 of the present embodiment, a pattern can be formed with high accuracy. Therefore, the production yield of the phase shift mask can be improved.

If pattern exposure is performed on a substrate to be exposed such as a wafer using a phase shift mask manufactured from the phase shift mask blanks 10 of the present embodiment, circuit pattern defects in the exposure step can be reduced, and high integration can be achieved. The yield in the device manufacturing process can be improved.

According to the above-described embodiment, the following operation and effect can be obtained.
(1) The phase shift mask blank 10 has a substrate 11 and a phase shift layer 12 formed on the substrate. The phase shift layer 12 contains chromium and oxygen, and arithmetically operates on the surface of the phase shift layer 12. The value of the average height is 0.38 nm or more. When the photoresist applied to the phase shift mask blanks 10 is wet-etched after pattern exposure, the phenomenon that the etchant permeates the interface between the phase shift layer 12 and the photoresist layer does not occur.

(2) The oxygen atom number concentration inside the phase shift layer 12 (at a predetermined depth) is larger than a predetermined value. For example, the oxygen atom number concentration at a depth of 1.25 nm (described later) from the surface of the phase shift layer 12 is 42.6% or more. When the photoresist applied to the phase shift mask blanks 10 is wet-etched after pattern exposure, the phenomenon that the etchant permeates the interface between the phase shift layer 12 and the photoresist layer does not occur.

(3) In the step of manufacturing a phase shift mask using the phase shift mask blanks 10 of the present embodiment, the etchant does not soak into the phase shift layer 12 at the edge of the pattern. That is, an inclined surface is not generated in the phase shift layer 12 due to such a penetration of the etching solution. For this reason, since the pattern accuracy of the phase shift mask manufactured using the phase shift mask blanks 10 of the present embodiment can be improved, the yield of the phase shift mask manufacturing process can be improved. Conventionally, an inclined surface may be formed at the edge of the pattern due to the penetration of the etching solution, which has caused a decrease in yield. By performing the exposure process using the phase shift mask manufactured from the phase shift mask blanks 10 of the present embodiment, it is possible to manufacture devices with a high degree of integration with a high yield.

(Example 1)
A substrate 11 made of synthetic quartz glass was prepared. The phase shift layer 12 was formed on the surface of the glass substrate 11 using the in-line type sputtering apparatus 100 shown in FIG. Hereinafter, a method for manufacturing the phase shift layer 12 will be described in more detail.

Argon (Ar), carbon dioxide (CO ₂ ), and nitrogen (N ₂ ) are introduced into the sputtering chamber 21 from the first gas inlet 31 and oxygen (O ₂ ) is introduced from the second gas inlet 32. Was introduced. The flow rates of each gas of Ar, CO ₂ , N ₂ , and O ₂ are 240 sccm, 42 sccm, 135 sccm, and 1.5 sccm, respectively, and the flow rate of each gas is set so that the pressure in the sputtering chamber 21 is maintained at 0.3 Pa. And the displacement was controlled. The power of the DC power supply of the sputtering chamber 21 is set to 9 kW (constant power control), and the sputtering is performed while moving the substrate 11 in the direction of the dotted arrow 25. Then, a phase shift mask blank 10 was produced.

において In the phase shift mask blank 10 manufactured by the above procedure, the arithmetic mean height Sa of the surface of the phase shift layer 12 was measured within a range of 220 μm × 220 μm by using a coherence scanning interferometer (NewView8000 manufactured by Zygo). In addition, the distribution of the oxygen atom number concentration in the depth direction of the phase shift layer 12 was measured by an X-ray photoelectron spectrometer (Quanta II manufactured by PHI).

The measurement of the distribution of the oxygen atom number concentration in the depth direction of the phase shift layer 12 by the X-ray photoelectron spectrometer was performed in the following procedure. A reference substrate in which an SiO ₂ film was formed on the surface of a synthetic quartz glass substrate similar to the substrate 11 by sputtering was prepared. The reference substrate is set in an X-ray photoelectron spectroscopy analyzer, and the SiO ₂ film is sputtered by a sputter ion gun provided in the X-ray photoelectron spectroscopy analyzer to perform etching. At this time, the relationship between the etching time of the SiO ₂ film and the etching amount (etching depth) is obtained. Next, the phase shift mask blank 10 produced in Example 1 is set in an X-ray photoelectron spectrometer, and the oxygen atom concentration is measured while sputtering the phase shift layer 12 with a sputter ion gun. At this time, the relationship between the etching time and the etching depth of the phase shift layer 12 is regarded as the same as the relationship between the etching time and the etching amount (etching depth) of the SiO ₂ film. That is, it is assumed that the etching depth for a certain etching time is the same for the SiO ₂ film and the phase shift layer 12. Based on this procedure, the oxygen atom number concentration distribution in the depth direction of the phase shift layer 12 is obtained.

As described above, the measurement of the oxygen atom number concentration by the X-ray photoelectron spectrometer is performed while etching the phase shift layer 12 by the sputter ion gun. The range to be etched by the sputter ion gun extends over a range of several hundred micrometers in diameter, and the value of the oxygen atom number concentration by the X-ray photoelectron spectroscopy analyzer outputs an average value in the same range. Although fine irregularities are formed on the surface of the phase shift layer 12, the measured oxygen atom number concentration indicates that the phase shift layer 12 in a range that includes many such fine irregularities on the surface can be removed by a sputter ion gun. It is considered that the etching is performed for a predetermined time, and the average value of the oxygen atom number concentration in the range is measured. The present inventors measured the various physical quantities described above for the comparative example in which the flow rate of oxygen in the step of forming the phase shift layer was zero, Example 1 in which 1.5 sccm was used, and Example 2 in which 3 sccm was used. .
Since the outermost surface of the phase shift layer 12 is highly likely to be contaminated by adsorption of atmospheric gas or the like, when actually performing a composition analysis on the phase shift layer 12, the degree of surface roughness is taken into consideration. It is preferable to remove a certain amount of the outermost phase shift layer. For this reason, in the present embodiment, the atomic concentration at the position etched from the outermost surface to a depth of 1.25 nm is defined as the surface atomic concentration of the phase shift layer 12, but the etching depth for obtaining the surface composition is set to this value. It is not limited to.

測定 The measurement results are shown in the table of FIG. According to FIG. 3, the arithmetic average height of the surface of the phase shift layer 12 manufactured in Example 1 is 0.402 nm. The arithmetic mean height of the surface of the phase shift layer 12 is larger than the arithmetic mean height of the surface of the substrate 11 by 0.04 nm. Further, in the phase shift layer 12, the oxygen atom number concentration at a depth of 1.25 nm from the surface is 42.6%, and the oxygen atom number concentration at a depth of 85 nm from the surface is 26.8%. The ratio of the oxygen atom number concentration at a depth of 1.25 nm from the surface to the oxygen atom number concentration at a depth of 85 nm from the surface of the phase shift layer 12 is 1.59.

The prepared phase shift mask blanks 10 are subjected to UV cleaning for 10 minutes, then spin cleaning (megasonic cleaning, alkali cleaning, brush cleaning, rinsing, and spin drying) for 15 minutes, and a photoresist (Nagase ChemteX Corporation) using a spin coater. A company (GRX-M237) was applied on the surface of the phase shift layer 12 to form a photoresist layer. After exposing in a line and space pattern of 2 μm pitch using a mask aligner, development was performed to partially remove the photoresist layer to form a resist pattern. Using this resist pattern as a mask, the phase shift mask blank 10 on which the resist pattern has been formed is immersed in an etchant (Pure Etch CR101 manufactured by Hayashi Junyaku Kogyo Co., Ltd.) and wet-etched to form a pattern on the phase shift layer 12. Was formed.

After forming the pattern, the pattern is cleaved and the cross-sectional shape of the pattern is observed with a scanning electron microscope (SEM) to determine whether or not the etchant seeps into the interface between the photoresist layer and the phase shift layer 12. Was confirmed by the cross-sectional shape of the pattern. When a pattern is formed on the phase shift layer 12 by wet etching after exposing the photoresist layer formed on the phase shift mask blanks 10 manufactured in Example 1, an interface between the photoresist layer and the phase shift layer 12 is formed. It was confirmed that the etchant did not soak.

(Example 2)
A substrate 11 made of the same synthetic quartz glass as the substrate 11 used in Example 1 was prepared. When forming the phase shift layer 12, in Example 1, the flow rate of oxygen (O ₂ ) introduced into the sputtering chamber 21 was 1.5 sccm, but in this example, the flow rate of oxygen (O ₂ ) was 3 sccm. Otherwise, the phase shift layer 12 was formed under the same conditions as in Example 1. The same items as in Example 1 were measured. The measurement results are shown in the table of FIG.

According to FIG. 3, the value of the arithmetic average height of the surface of the phase shift layer 12 manufactured in Example 2 is 0.417 nm. The arithmetic mean height of the surface of the phase shift layer 12 is larger than the arithmetic mean height of the surface of the substrate 11 by 0.05 nm. In the phase shift layer 12, the oxygen atom concentration at a depth of 1.25 nm from the surface is 43.5%, the oxygen atom concentration at a depth of 85 nm from the surface is 27.2%, and The ratio of the oxygen atom number concentration at a depth of 1.25 nm from the surface to the oxygen atom number concentration at a depth of 85 nm from the surface of the phase shift layer 12 is 1.60.
When a pattern is formed on the phase shift layer 12 by wet etching after forming a photoresist layer on the shift mask blanks 10 manufactured in Example 2, the interface between the photoresist layer and the phase shift layer 12 is stained with an etchant. It was confirmed that no jamming phenomenon occurred.

FIG. 4 shows a pattern formed by wet etching after exposing a photoresist layer 15 formed on the phase shift mask blanks 10 manufactured according to the first and second embodiments, and cutting the pattern. It is a figure which shows the mode observed by the microscope (SEM) typically. This indicates that the etchant does not permeate the interface between the photoresist layer 15 and the phase shift layer 12.

(Comparative Example 1)
A substrate 51 made of the same synthetic quartz glass as the substrate 11 used in Example 1 was prepared. No oxygen was introduced into the sputtering chamber 21 when forming the phase shift layer, that is, the amount of oxygen (O ₂ ) introduced was set to 0 sccm, and the phase shift layer was formed under the same conditions as in Example 1 except for that. did. That is, in Comparative Example 1, oxygen was not introduced into the sputtering chamber 21 when forming the phase shift layer. FIG. 6 is a schematic diagram illustrating a configuration of the phase shift mask blank 50 manufactured in Comparative Example 1. The surface of the phase shift layer 52 of the phase shift mask blank 50 manufactured in Comparative Example 1 has no surface roughness of a predetermined arithmetic average height. In the phase shift mask blanks 50 according to Comparative Example 1, the same items as in Example 1 were measured for the phase shift layer 52 formed on the surface of the substrate 51.

The measurement results are shown in the table of FIG. According to FIG. 3, the value of the arithmetic average height of the surface of the phase shift layer 52 manufactured in Comparative Example 1 is 0.359 nm. In this phase shift layer 52, the oxygen atom concentration at a depth of 1.25 nm from the surface is 42.1%, and the oxygen atom concentration at a depth of 85 nm from the surface is 31.8%. The ratio of the oxygen atom number concentration at a depth of 1.25 nm from the surface to the oxygen atom number concentration at a depth of 85 nm from the surface of the phase shift layer 52 is 1.32. Further, the phase shift mask blank 50 in which a photoresist layer is formed on the phase shift layer 52 manufactured in Comparative Example 1, when the pattern is formed on the phase shift layer 52 by wet etching, It was confirmed that the etchant permeated the interface.

FIG. 7 shows a pattern formed by wet etching after exposing a photoresist layer 55 formed on the phase shift mask blanks 50 manufactured according to Comparative Example 1, cutting the pattern, and cross-sectioning the pattern with a scanning electron microscope ( It is a figure which shows the mode observed by SEM) typically. This indicates that an inclined surface formed by the infiltration of the etching solution at the interface between the photoresist layer 55 and the phase shift layer 52 is formed in the phase shift layer 52.

In the phase shift mask in which such an inclined surface is generated, the area of the phase shift layer having an original film thickness is reduced due to the generation of the inclined surface, so that the function of the phase shift of the exposure light is reduced. As a result, when a circuit pattern is formed on a device substrate using such a phase shift mask, the accuracy of the circuit pattern decreases. Therefore, such a phase shift mask is not suitable for manufacturing a device.
From the above experimental results, it is preferable that the arithmetic surface roughness of the phase shift layer 12 is 0.38 nm or more. Further, the oxygen atom concentration at a depth of 1.25 nm from the surface of the phase shift layer 12 is preferably 42.6% or more. The oxygen atom concentration at a depth of 1.25 nm from the surface of the phase shift layer 12 is preferably higher than the oxygen atom concentration at a depth of 85 nm, and the ratio is preferably higher than 1.59.
The phase shift mask blank of the present embodiment having such an aspect has a tendency that the etchant does not easily permeate between the photoresist and the phase shift layer at the time of wet etching, and the pattern of exposure light at the time of photoresist exposure is Thus, an accurate mask pattern can be formed.

であれば The arithmetic average height of the surface of the phase shift layer 12 is not particularly limited as long as the desired contrast performance is obtained. However, if the arithmetic average height of the surface of the phase shift layer 12 is too large, the scattering of the exposure light on the surface of the phase shift layer 12 increases, and the sharpness at the edge of the exposure pattern decreases. The upper limit value of Sa is preferably set to 1.0 nm.

According to the measurement result of the atomic number concentration by the X-ray photoelectron spectrometer, oxygen is larger than the stoichiometric ratio in the phase shift layer 12 of the CrOCN film formed in the present embodiment. Thereby, the adhesion between the photoresist layer and the phase shift layer 12 can be improved, and the penetration of the etchant can be suppressed. For example, the phase shift layer 12 in the present embodiment may be formed of a film made of CrOCN (Cr: O: C: N = 51: 27: 5: 18 at.%). In this specification, the expression “the composition of the CrOCN film is stoichiometric” means that the atomic ratio is Cr: O: C: N = 1: 1: 1: 1.

表面 The surface of the substrate 11 of the phase shift mask blank 10 is finished by polishing. On the other hand, the phase shift layer 12 is formed by sputtering. Therefore, the arithmetic average height of the surface of the phase shift layer 12 is usually larger than the arithmetic average height of the surface of the substrate 11, but the arithmetic average height of the surface of the phase shift layer 12 is set to be a predetermined value higher than the arithmetic average height of the substrate 11. By increasing the size, the adhesiveness of the photoresist pattern formed on such a phase shift mask blank can be improved. For example, such an effect can be obtained by making the arithmetic average height of the surface of the phase shift layer 12 larger than the arithmetic average height of the surface of the substrate 11 by 0.04 nm or more. From the viewpoint of scattering of exposure light on the surface of the phase shift layer 12, the upper limit of the difference between the arithmetic average height of the surface of the phase shift layer 12 and the arithmetic average height of the surface of the substrate 11 is preferably 1.0 nm.

The following modifications are also within the scope of the present invention, and one or more of the modifications can be combined with the above-described embodiment.

(Modification 1)
In the above-described embodiment, when forming the phase shift layer 12 by sputtering, the flow rate of oxygen introduced into the sputtering chamber is adjusted so that the arithmetic average height of the surface of the phase shift layer 12 is within a predetermined range. However, instead of adjusting the flow rate of oxygen introduced into the sputtering chamber, after forming the phase shift layer 12, the surface thereof may be dry-etched or wet-etched to form surface irregularities at a predetermined arithmetic average height. Good. Thereby, the adhesion between the photoresist layer formed on the surface of the phase shift layer 12 and the phase shift layer 12 can be improved.

(Modification 2)
The phase shift mask blanks 10 described in the above embodiments and modifications can be applied as phase shift mask blanks for manufacturing phase shift masks for manufacturing display devices, manufacturing semiconductors, and manufacturing printed circuit boards. In the case of a phase shift mask blank for manufacturing a phase shift mask for manufacturing a display device, a substrate having a size of 520 mm × 800 mm or more can be used as the substrate 11. The thickness of the substrate 11 may be 8 to 21 mm.

(Exposure equipment)
Next, as an application example of the phase shift mask manufactured by using the phase shift mask blanks 10 manufactured according to the first and second embodiments, a photolithography process for manufacturing a semiconductor or a liquid crystal panel will be described with reference to FIG. . In the exposure apparatus 500, a phase shift mask 513 manufactured using the phase shift mask blanks 10 manufactured in the first and second embodiments is arranged. Further, a photosensitive substrate 515 coated with a photoresist is set 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 phase shift mask 513, a projection optical system 504, and an exposure object support for holding a photosensitive substrate 515 as an exposure object. A table 505 and a drive mechanism 506 for moving the exposure object support table 505 in a horizontal plane are provided. Exposure light emitted from the light source LS of the exposure apparatus 500 enters the illumination optical system 502, is adjusted to a predetermined light flux, and is emitted to the phase shift mask 513 held on the mask support 503. The light that has passed through the phase shift mask 513 has an image of the device pattern drawn on the phase shift mask 513, and this light is transferred to the photosensitive substrate held on the exposure object support table 505 via the projection optical system 504. A predetermined position 515 is irradiated. Thereby, the image of the device pattern of the phase shift mask 513 is imagewise exposed on the photosensitive substrate 515 such as a semiconductor wafer or a liquid crystal panel at a predetermined magnification.
By using the phase shift mask of the embodiment, pattern defects in the exposure step can be reduced, and the yield in the exposure step can be improved.

Although various embodiments and modified examples have been described above, the present invention is not limited to these contents. Other embodiments that can be considered within the scope of the technical concept of the present invention are also included in the scope of the present invention.

The disclosure of the following priority application is incorporated herein by reference.
Japanese Patent Application No. 2018-172898 (filed on Sep. 14, 2018)

10: phase shift mask blanks, 11: substrate, 12: phase shift layer, 100: manufacturing apparatus

Claims

A substrate, a phase shift mask blank having a phase shift layer formed on the substrate,
The phase shift layer contains chromium and oxygen,
A phase shift mask blank, wherein the value of the arithmetic average height of the surface of the phase shift layer is 0.38 nm or more.
The phase shift mask blank according to claim 1,
A phase shift mask blank, wherein the value of the arithmetic average height on the surface of the phase shift layer is greater than the value of the arithmetic average height on the surface of the substrate by 0.04 nm or more.
A substrate, a phase shift mask blank having a phase shift layer formed on the substrate,
The phase shift layer contains chromium and oxygen,
A phase shift mask blank, wherein the value of the arithmetic average height on the surface of the phase shift layer is greater than the value of the arithmetic average height on the surface of the substrate by 0.04 nm or more.
The phase shift mask blank according to any one of claims 1 to 3,
The phase shift mask blank, wherein the phase shift layer is made of CrOCN or a material in which oxygen in CrOCN is higher than a stoichiometric ratio.
In the phase shift mask blank according to any one of claims 1 to 4,
A phase shift mask blank, wherein the oxygen atom concentration at a depth of 1.25 nm from the surface of the phase shift layer is 42.6% or more.
The phase shift mask blank according to any one of claims 1 to 5, wherein the oxygen atom concentration on the surface side of the phase shift layer is higher than the oxygen atom concentration on the substrate side. Blanks.
In the phase shift mask blank according to any one of claims 1 to 6,
A phase shift mask, wherein a ratio of the oxygen atom number concentration at a depth of 1.25 nm from the surface of the phase shift layer to the oxygen atom number concentration at a depth of 85 nm from the surface of the phase shift layer is 1.59 or more. Blanks.
In the phase shift mask blank according to any one of claims 1 to 7,
A phase shift mask blank, wherein the surface of the phase shift layer is wet-etched or dry-etched.
In the phase shift mask blank according to any one of claims 1 to 8,
The phase shift mask blank, wherein the size of the substrate is 520 mm × 800 mm or more.
A phase shift mask of the phase shift mask blank according to any one of claims 1 to 9, wherein the phase shift layer is formed in a predetermined pattern.
An exposure method, wherein the photosensitive substrate coated with the photoresist is exposed through the phase shift mask according to claim 10.
An exposure step of exposing the photosensitive substrate by the exposure method according to claim 11,
A developing step of developing the exposed photosensitive substrate,
A method for manufacturing a device, comprising: