TWI818992B - Phase shift mask blank, manufacturing method of phase shift mask blank, phase shift mask, manufacturing method of phase shift mask, exposure method, and component manufacturing method - Google Patents

Abstract

The phase shift mask blank of the present invention has a substrate and a phase shift layer formed on the substrate. The phase shift layer contains chromium and oxygen. The arithmetic mean height of the surface of the phase shift layer is 0.38 nm or more.

Description

Phase shift mask blank, manufacturing method of phase shift mask blank, phase shift mask, manufacturing method of phase shift mask, exposure method, and component manufacturing method

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

There is known a phase shift mask in which a phase shift layer made of chromium oxynitride is formed on a transparent substrate (Patent Document 1). There has always been a desire to improve the quality of phase shift masks.

[Prior technical literature]

[Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2011-013283

According to the first aspect of the present invention, the phase shift mask blank has a substrate and a phase shift layer formed on the substrate, the phase shift layer contains chromium and oxygen, and the value of the arithmetic mean height of the surface of the phase shift layer is 0.38nm or above.

According to the second aspect of the present invention, the phase shift mask blank has a substrate and a phase shift layer formed on the substrate, the phase shift layer contains chromium and oxygen, and the value of the arithmetic mean height of the surface of the phase shift layer It is greater than the arithmetic mean height value of the surface of the above-mentioned substrate by more than 0.04nm.

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

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

According to a fifth aspect of the present invention, a method for manufacturing an element includes: an exposure step of exposing the above-mentioned photosensitive substrate by the exposure method of the fourth aspect; and a development step of making the exposed photosensitive substrate Substrate development.

10: Phase shift mask blank

11:Substrate

12: Phase shift layer

12a: Concave and convex parts

100: Manufacturing device

FIG. 1 is a diagram showing an example of the structure of a phase shift mask blank according to the embodiment.

FIG. 2 is a schematic diagram showing an example of a manufacturing device used for manufacturing a phase shift mask blank.

FIG. 3 is a table showing measurement results of phase shift mask blanks of Examples and Comparative Examples.

4 is a schematic diagram illustrating a cross-section of a mask pattern formed using a phase-shifted mask blank according to an embodiment.

FIG. 5 is a conceptual diagram showing a state of exposing a photosensitive substrate through a phase shift mask.

FIG. 6 is a diagram showing an example of the structure of a phase shift mask blank according to a comparative example.

7 is a schematic diagram illustrating a cross-section of a mask pattern formed using a phase-shifted mask blank of a comparative example.

(implementation form)

FIG. 1 is a diagram showing a structural example of a phase shift mask blank 10 according to this embodiment. The phase shift mask blank 10 includes a substrate 11 and a phase shift layer 12 . In this embodiment, the phase shift layer 12 is formed on the surface of the substrate 11 by sputtering. At this time, the oxygen content (oxygen atomic number concentration) in the phase shift layer 12 is set according to the sputtering conditions, thereby forming a predetermined alignment (predetermined arithmetic mean) on the surface of the phase shift layer 12 as shown in FIG. 1 high) fine unevenness (concave-convex portion 12a).

Hereinafter, the phase shift mask blank 10 of this embodiment will be described in further detail.

As a material of the substrate 11, for example, synthetic quartz glass is used. Furthermore, the material of the substrate 11 is not limited to synthetic quartz glass. Phase shift masks are used when manufacturing display components such as FPD (Flat Panel Display) or semiconductor components such as LSI (Large Scale Integration). The substrate 11 may be one that can sufficiently transmit exposure light during the exposure step of exposing a wafer or other exposure target base material using a phase shift mask.

The phase shift layer 12 is formed in the form of a film on the surface of the substrate 11 using a material containing chromium (Cr) and oxygen (O). The phase shift layer 12 of this embodiment is composed of a film made of CrOCN. A required 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 irradiated exposure light in the exposure step.

When the component substrate is exposed with exposure light through a phase shift mask having the phase shift layer 12 formed with a desired thickness and a desired pattern, the light transmitted through the portion where the phase shift layer 12 is present and the light transmitted through the portion without phase shift Part of the light in layer 12 produces a phase difference (phase shift amount) of approximately 180°. Thereby, the intensity of the exposure light irradiated to areas other than the exposure pattern area is controlled to be lower, thereby improving the contrast of the exposure pattern. 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 the phase of the exposure light generates a phase shift amount of approximately 180°. However, the phase shift amount of the exposure light is not limited to 180° as long as it is within the range required to obtain the required contrast in the exposure step. Furthermore, the phase shift layer 12 may be composed of a single film, or may be formed by laminating a plurality of films.

The phase shift mask in which the required pattern is formed on the phase shift layer 12 of the phase shift mask blank 10 is produced, for example, according to the procedure described below.

A photoresist is coated on the surface of the phase shift layer 12 to form a photoresist layer. The formed photoresist layer is irradiated with energy lines such as laser light, electron beam or ion beam to draw a pattern. By making the patterned photoresist layer appear Shadow, remove the painted part or the non-painted part, and form a pattern on the photoresist layer. Using the patterned photoresist layer as a photomask, wet etching is performed on the phase shift layer 12 . Through this wet etching, a shape corresponding to the pattern formed in the photoresist layer is formed (transferred) in the phase shift layer 12 . Remove the photoresist layer to complete the phase shift mask.

The present inventors investigated the correlation between the arithmetic mean height of the surface of the phase shift layer 12 and the oxygen atom number concentration of the phase shift layer 12 , and further investigated the phase shift when patterning the photoresist layer formed on the phase shift layer 12 The interface between layer 12 and the photoresist layer was investigated. As a result, the following insights were obtained. Furthermore, the arithmetic mean height in this manual is that specified by ISO25178.

(1) The inventors found that when the arithmetic mean height of the surface of the phase shift layer 12 is greater than a predetermined value, for example, when it is 0.38 nm or more, phase shift is formed using this phase shift mask blank. During the patterning step of layer 12, the interface between the phase shift layer 12 and the photoresist layer will not allow penetration of the etching liquid.

It can be inferred that when the arithmetic mean height of the surface of the phase shift layer 12 is greater than a predetermined value, the penetration of the etching liquid at the interface between the phase shift layer 12 and the photoresist layer can be suppressed. The reason is that the surface of the phase shift layer 12 is formed Due to the moderate roughness (concave-convex), the adhesion between the photoresist layer and the phase shift layer 12 becomes high enough to inhibit the penetration of the etching liquid.

(2) When it is found that the difference between the arithmetic mean height of the surface of the phase shift layer 12 and the arithmetic mean height of the surface of the substrate 11 is greater than a predetermined value, for example, it is greater than 0.04nm or more, when using this phase shift mask blank During the step of forming the pattern of the phase shift layer 12, the interface between the phase shift layer 12 and the photoresist layer does not allow penetration of the etching liquid.

(3) It was found that roughness (roughness) of a predetermined arithmetic mean height can be generated on the surface of the phase shift layer 12 in the following manner. It is known that when the phase shift layer 12 is formed by sputtering, the flow rate of oxygen introduced into the sputtering chamber is adjusted, and the phase shift layer 12 contains more than a predetermined amount of oxygen, thereby forming a surface with a predetermined arithmetic mean height. Phase shift layer 12. That is, the present inventors discovered that there is a correlation between the arithmetic mean height of the uneven 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) The inventors found that when the concentration of the number of oxygen atoms in the surface of the phase shift layer 12 formed in the phase shift mask blank 10 is greater than a predetermined value, the phase shift layer 12 and the photoresist layer do not move toward each other. The penetration of etching liquid at the interface.

As discussed in (3) above, if the phase shift layer 12 has a concentration of oxygen atoms on the surface that is greater than a predetermined value, the arithmetic mean height of the surface of the phase shift layer 12 is above the predetermined value (for example, 0.38 nm). Therefore, it has an appropriate The roughness (concave-convex). It is considered that when the photoresist layer is formed on the surface of the phase shift layer 12, the adhesion between the phase shift layer 12 and the photoresist layer is high. Therefore, the interface between the phase shift layer 12 and the photoresist layer does not occur during wet etching. Penetration of the etching liquid.

(5) It is known that when the number concentration of oxygen atoms in the interior of the phase shift layer 12 formed by 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 Penetration of etching liquid at the interface of the photoresist layer. An example of the oxygen atomic number concentration in the interior of the phase shift layer 12 decreasing in the depth direction from the surface of the phase shift layer 12 is given. For example, the oxygen atomic number concentration at a position 1.25 nm deep from the surface of the phase shift layer 12 is relative to The ratio of the oxygen atomic number concentration at the position 85 nm deep from the surface of the phase shift layer 12 is 1.59 or more.

Hereinafter, an example of a method of manufacturing the phase shift mask blank 10 of this embodiment will be described.

(Phase shift mask blank manufacturing method)

FIG. 2 is a schematic diagram showing an example of a manufacturing device used to form the phase shift layer 12 when manufacturing the phase shift mask blank 10 of this embodiment. FIG. 2( a ) is a schematic view of the inside of the manufacturing device 100 when viewed from above, and FIG. 2( b ) is a schematic view of the inside of the manufacturing device 100 when viewed from the side. The manufacturing apparatus 100 shown in FIG. 2 is an in-line sputtering apparatus, which includes a chamber 20 for loading the substrate 11 for forming the phase shift layer 12, a sputtering chamber 21, and a sputtering chamber 21. The substrate 11 on which the phase shift layer 12 is formed is moved out of the chamber 22 . The target 41 for forming the phase shift layer 12 is disposed in the sputtering chamber 21 .

The substrate tray 30 is a frame-shaped tray capable of placing the substrate 11 for forming the phase shift layer 12, and supports and places the outer edge portion of the substrate 11. The surface of the substrate 11 is ground and cleaned to form a phase shift The layer 12 is placed on the substrate tray 30 with the surface facing downward. In the sputtering apparatus 100, as described below, the substrate tray 30 on which the substrate 11 is placed is moved in the direction indicated by the dotted arrow 25 in FIG. 2 while maintaining the surface of the substrate 11 facing the target 41. A phase shift layer 12 is formed on the surface of 11 .

A gate valve (not shown) is provided between each of the loading chamber 20, the sputtering chamber 21, and the loading chamber 22, and each chamber is connected and blocked by the opening and closing of the gate valve. The carry-in chamber 20, the sputtering chamber 21, and the carry-out chamber 22 are respectively connected to an exhaust device (not shown) to exhaust the air inside each chamber.

In addition, a sufficient space or other waiting room (not shown) is provided between each gate valve and the target 41 to allow the substrate tray 30 to wait before and after film formation.

As described above, the target 41 is provided inside the sputtering chamber 21 . The target 41 is a sputtering target used to form 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 kind selected from the group consisting of chromium, chromium oxides, chromium nitrides, chromium carbides, and the like. In this embodiment, chromium is selected as 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 gas for sputtering into the sputtering chamber 21 . The first gas inlet 31 is disposed on the side close to the loading chamber 20 , that is, on the 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 close to the unloading chamber 22 , that is, on the downstream side with respect to the traveling direction of the substrate tray 30 .

In this embodiment, a CrOCN film is formed as the phase shift layer 12 . Therefore, a mixed gas of a carbon-containing gas such as nitrogen and carbon dioxide, and an inert gas (argon gas is used in this embodiment) is introduced into the sputtering chamber 21 through the first gas inlet 31 . Furthermore, oxygen is introduced through the second gas inlet 32 .

The substrate 11 is transferred from the loading chamber 20 to the sputtering chamber 21, and sputtering is started. At this time, since nitrogen gas, carbon-containing gas, and inert gas are introduced from the first gas inlet 31 , sputtering starts on the side close to the first gas inlet 31 in the sputtering chamber 21 , that is, with respect to the substrate 11 In the side, these gases The concentration is relatively high. On the other hand, since oxygen 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 with respect to the substrate 11 where sputtering is completed, is relatively high. Therefore, in the formed CrOCN film, sputtering continues as the substrate 11 moves to the right, that is, as the film thickness becomes thicker, the oxygen atomic number concentration becomes higher. As a result, the side closer to the surface of the phase shift layer 12 (the side where the phase shift layer 12 is finally deposited) contains relatively more oxygen, while the side closer to the substrate (the side where the initial deposition occurs) contains less oxygen. . The surface of the phase shift layer 12 formed in this manner has a roughness (asperity) of a predetermined arithmetic mean height. 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 .

The substrate 11 on which the phase shift layer 12 is formed is transported to the unloading chamber 22 . In this way, the phase shift layer 12 is formed on the surface of the substrate 11 and the phase shift mask blank 10 is produced.

Furthermore, the material of the target 41 and the types of gases introduced from the first gas inlet 31 and the second gas inlet 32 can be appropriately selected according to the materials or compositions constituting the phase shift layer 12 . In addition, as the sputtering method, any method such as DC sputtering and RF sputtering can be used.

As described above, in this embodiment, when the phase shift layer 12 is formed by sputtering, the flow rate of each gas introduced into the sputtering chamber 21 (especially the flow rate of oxygen) is adjusted. Thereby, the number of oxygen atoms contained in the phase shift layer 12 is adjusted, and the roughness (arithmetic mean 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 fully improved, and the penetration of the etching liquid toward the interface between the phase shift layer 12 and the photoresist layer can be prevented. Furthermore, by manufacturing a phase shift mask using the phase shift mask blank 10 of this embodiment, a pattern can be formed with high accuracy. Therefore, the manufacturing yield of the phase shift mask can be improved.

If a phase shift mask manufactured according to the phase shift mask blank 10 of this embodiment is used to perform pattern exposure on an exposure target substrate such as a wafer, circuit pattern defects in the exposure step can be reduced, and components with high integration can be improved. Yield in manufacturing steps.

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

(1) The phase shift mask blank 10 has a substrate 11 and a phase shift layer 12 formed on the substrate. The layer 12 contains chromium and oxygen, and the arithmetic mean height of the surface of the phase shift layer 12 is 0.38 nm or more. When the photoresist coated on the phase shift mask blank 10 is wet-etched after pattern exposure, the etching liquid will not penetrate into the interface between the phase shift layer 12 and the photoresist layer.

(2) The concentration of oxygen atoms in the interior of the phase shift layer 12 (predetermined depth) is greater than a predetermined value. For example, the oxygen atomic number concentration at a depth of 1.25 nm from the surface of the phase shift layer 12 (described below) is 42.6% or more. When the photoresist coated on the phase shift mask blank 10 is wet-etched after pattern exposure, the etching liquid will not penetrate into the interface between the phase shift layer 12 and the photoresist layer.

(3) In the step of manufacturing a phase shift mask using the phase shift mask blank 10 of this embodiment, penetration of the etching liquid does not occur in the phase shift layer 12 at the edge of the pattern. That is, the penetration of the etching liquid does not cause an inclined surface in the phase shift layer 12 . Therefore, the pattern accuracy of the phase shift mask manufactured using the phase shift mask blank 10 of this embodiment can be improved, and therefore the yield of the manufacturing step of the phase shift mask can be improved. It is known that the penetration of etching liquid causes the formation of inclined surfaces at the edge of the pattern, which is the reason for the decrease in yield. By performing the exposure step using the phase shift mask manufactured according to the phase shift mask blank 10 of this embodiment, a high-density device can be manufactured with high yield.

(Example 1)

A substrate 11 made of synthetic quartz glass is prepared. The continuous sputtering device 100 shown in FIG. 2 is used to form the phase shift layer 12 on the surface of the glass substrate 11 . The manufacturing method of the phase shift layer 12 will be described in further detail below.

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 . The flow rates of each gas of Ar, CO ₂ , N ₂ , and O ₂ are set to 240 sccm, 42 sccm, 135 sccm, and 1.5 sccm respectively. The flow rate and exhaust volume of each gas are controlled to maintain the pressure in the sputtering chamber 21 at 0.3 Pa. . The power of the DC power supply of the sputtering chamber 21 is set to 9kW (the control power is fixed), while the substrate 11 is moved in the direction of the dotted arrow 25, sputtering is performed, and CrOCN is formed on the substrate 11 to a thickness of 170 nm. The phase shift layer 12 is used to produce a phase shift mask blank 10 .

In the phase shift mask blank 10 produced by the above-mentioned procedures, the arithmetic mean height Sa of the surface of the phase shift layer 12 was measured in the range of 220 μm × 220 μm by a coherent scanning interferometer (NewView8000 manufactured by Zygo Corporation). . Furthermore, the distribution of the oxygen atom number concentration in the depth direction of the phase shift layer 12 was measured using an X-ray photoelectron spectrometer (Quantera II manufactured by PHI Corporation).

The distribution of the oxygen atom number concentration in the depth direction of the phase shift layer 12 obtained by using the X-ray photoelectron spectrometer is measured in the following sequence. A reference substrate in which an SiO ₂ film was formed on the surface of the same synthetic quartz glass substrate as the substrate 11 by sputtering was prepared. The reference substrate was mounted on an X-ray photoelectron spectrometer analyzer, and the SiO ₂ film was sputtered and etched using a sputtering ion gun equipped with the X-ray photoelectron spectrometer analyzer. At this time, the relationship between the etching time and the etching amount (etching depth) of the SiO ₂ film was determined. Next, the phase shift mask blank 10 produced in Example 1 was installed in an X-ray photoelectron spectrometer analyzer, and the oxygen atom number concentration was measured while sputtering the phase shift layer 12 using a sputtering ion gun. At this time, it is considered that the relationship between the etching time and the etching depth of the phase shift layer 12 is the same as the relationship between the etching time and the etching amount (etching depth) of the SiO ₂ film. That is, it is considered that the SiO ₂ film and the phase shift layer 12 have the same etching depth at a certain etching time. Based on this sequence, the oxygen atom number concentration distribution in the depth direction of the phase shift layer 12 is obtained.

The oxygen atomic number concentration obtained by the X-ray photoelectron spectrometer is measured as described above while etching the phase shift layer 12 with a sputtering ion gun. The etching range of the sputtering ion gun reaches a range of 100 μm in diameter, and the oxygen atom number concentration value obtained by the X-ray photoelectron spectrometer is used to output the average value of the same range. Fine unevenness is formed on the surface of the phase shift layer 12. The measured oxygen atomic number concentration is based on etching the phase shift layer 12 for a predetermined time by a sputtering ion gun in a range containing more of such fine unevenness on the surface. And measure the average value of the oxygen atomic number concentration within the range. The present inventors measured various physical quantities described above with respect to the comparative example in which the flow rate of oxygen in the formation step of the phase shift layer was set to zero, the Example 1 set to 1.5 sccm, and the Example 2 set to 3 sccm.

Furthermore, the uppermost surface of the phase shift layer 12 is highly likely to be contaminated due to adsorption of environmental gases, etc. Therefore, when actually analyzing the composition of the phase shift layer 12 , the degree of surface roughness is considered, and it is preferably removed to a certain extent. The most superficial phase shift layer. Therefore, in this embodiment, the atomic number concentration at the position etched from the outermost surface to a depth of 1.25 nm is used as the surface atomic number concentration of the phase shift layer 12 , but the etching depth used to obtain the surface composition is not limited to this value. .

The measurement results are shown in the table of FIG. 3 . According to FIG. 3 , the arithmetic mean height of the surface of the phase shift layer 12 produced in Example 1 is 0.402 nm. In addition, the arithmetic mean height of the surface of the phase shift layer 12 is 0.04 nm larger than the arithmetic mean height of the surface of the substrate 11 . Furthermore, in the phase shift layer 12, the oxygen atomic number concentration at a depth of 1.25 nm from the surface is 42.6%, the oxygen atomic number concentration at a depth of 85 nm from the surface is 26.8%, and the oxygen atomic number concentration at a depth of 1.25 nm from the surface is 26.8%. The ratio of the oxygen atomic 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 blank 10 is UV cleaned for 10 minutes, then spin cleaned (magnetic resonance cleansing, alkaline cleaning, brush cleaning, rinsing, and spin drying) for 15 minutes, and is then coated with a spin coater. Photoresist (GRX-M237 manufactured by Nagase Chemtex Co., Ltd.) is coated on the surface of the phase shift layer 12 to form a photoresist layer. Using a mask aligner, the pattern of lines and gaps with a pitch of 2 μm is exposed, and then developed to partially remove the photoresist layer to form a resist pattern. Using this resist pattern as a photomask, the phase shift photomask blank 10 on which the resist pattern is formed is immersed in an etching solution (Pure Etch CR101 manufactured by Hayashi Pure Chemical Industries, Ltd.) to perform wet etching, thereby performing phase shift. Layer 12 forms a pattern.

After the pattern is formed, it is cut, and a scanning electron microscope (SEM) is used to observe the cross-sectional shape of the pattern. Based on the cross-sectional shape of the pattern, it is confirmed whether penetration of the etching liquid occurs at the interface between the photoresist layer and the phase shift layer 12 . After confirming that after exposing the photoresist layer formed in the phase shift mask blank 10 produced in Example 1, and then forming a pattern on the phase shift layer 12 by wet etching, there is no difference between the photoresist layer and the phase shift layer 12. Penetration of etching liquid occurs at the interface.

(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 set to 1.5 sccm, but in this embodiment, the flow rate of oxygen (O ₂ ) was set to 3 sccm. , except for this, 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. 3 .

According to FIG. 3 , the arithmetic mean height value of the surface of the phase shift layer 12 produced in Example 2 is 0.417 nm. In addition, the arithmetic mean height of the surface of the phase shift layer 12 is greater than the arithmetic mean height of the surface of the substrate 11 by 0.05 nm. In the phase shift layer 12, the oxygen atomic number concentration at a depth of 1.25 nm from the surface is 43.5%, the oxygen atomic number concentration at a depth of 85 nm from the surface is 27.2%, and the oxygen atomic number concentration at a depth of 1.25 nm from the surface is 27.2%. The ratio of the oxygen atomic number concentration to the oxygen atomic number concentration at a depth of 85 nm from the surface of the phase shift layer 12 is 1.60.

It was confirmed that after the photoresist layer was formed on the phase shift mask blank 10 produced in Example 2, when the pattern was formed on the phase shift layer 12 by wet etching, no formation occurred at the interface between the photoresist layer and the phase shift layer 12 Penetration phenomenon of etching liquid.

After exposing the photoresist layer 15 formed in the phase shift mask blank 10 produced according to Embodiments 1 and 2, a pattern is formed by wet etching, cut off, and the pattern cross-section is observed with a scanning electron microscope (SEM). , Figure 4 is a diagram schematically showing this situation. This means that there is no penetration of the etching liquid at 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. When forming the phase shift layer, oxygen was not introduced into the sputtering chamber 21 , that is, the introduction amount of oxygen (O ₂ ) was 0 sccm. The phase shift layer was formed under the same conditions as in Example 1. 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 showing the structure of the phase shift mask blank 50 produced in Comparative Example 1. The surface of the phase shift layer 52 of the phase shift mask blank 50 produced in Comparative Example 1 did not have a surface roughness of a predetermined arithmetic mean height. In the phase shift mask blank 50 of Comparative Example 1, the same items as those of 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 Figure 3 . According to FIG. 3 , the arithmetic mean height value of the surface of the phase shift layer 52 produced in Comparative Example 1 is 0.359 nm. Furthermore, in the phase shift layer 52, the oxygen atomic number concentration at a depth of 1.25 nm from the surface is 42.1%, the oxygen atomic number concentration at a depth of 85 nm from the surface is 31.8%, and the oxygen atomic number concentration at a depth of 1.25 nm from the surface is 31.8%. The ratio of the oxygen atomic number concentration to the oxygen atomic number concentration at a depth of 85 nm from the surface of the phase shift layer 52 is 1.32. Furthermore, it was confirmed that when the phase shift mask blank 50 in which the photoresist layer was formed in the phase shift layer 52 produced in Comparative Example 1 was patterned on the phase shift layer 52 by wet etching, there was a gap between the photoresist layer and the phase shift layer. The interface part of 52 produces the penetration of etching liquid.

After exposing the photoresist layer 55 formed in the phase shift mask blank 50 produced in Comparative Example 1, a pattern was formed by wet etching, and then cut, and the pattern cross-section was observed with a scanning electron microscope (SEM). , Figure 7 is a diagram schematically showing this situation. It shows that the phase shift layer 52 is formed with an inclined surface caused by the penetration of the etching liquid at the interface between the photoresist layer 55 and the phase shift layer 52 .

The phase-shift mask that generates such an inclined surface reduces the area of the phase-shift layer with the original film thickness due to the inclined surface, so the phase-shifting function of the exposed light is weakened. As a result, if such a phase shift mask is used to form a circuit pattern on a device substrate, the accuracy of the circuit pattern will be reduced. Therefore, this type of phase shift mask is not suitable for component manufacturing.

According to the above experimental results, the arithmetic surface roughness of the phase shift layer 12 is preferably above 0.38 nm. In addition, the oxygen atom concentration in the depth of 1.25 nm from the surface of the phase shift layer 12 is preferably 42.6% or more. In addition, the oxygen atom concentration at a depth of 1.25 nm from the surface of the phase shift layer 12 is preferably greater than the oxygen atom concentration at a depth of 85 nm, and the ratio is preferably greater than 1.59.

The phase-shift mask blank of the present embodiment with related aspects has a tendency that the etching liquid does not easily penetrate between the photoresist and the phase-shift layer during wet etching, and can form a pattern of the exposure light when the photoresist is exposed. Accurate mask pattern.

The arithmetic mean height of the surface of the phase shift layer 12 is not particularly limited as long as it is within the range to obtain the required contrast performance. However, if the arithmetic mean height of the surface of the phase shift layer 12 becomes too large, the scattering of the exposure light in the surface of the phase shift layer 12 becomes larger, and the sharpness on the edge of the exposure pattern is reduced, so the arithmetic mean height of the surface The upper limit of Sa is preferably 1.0 nm.

According to the measurement results of the atomic number concentration using an X-ray photoelectron spectrometer, in the phase shift layer 12 formed using the CrOCN film formed in this embodiment, oxygen is higher than the stoichiometric ratio. In this way, the adhesion between the photoresist layer and the phase shift layer 12 can be improved and the penetration of the etching liquid can be suppressed. For example, the phase shift layer 12 in this embodiment can also be formed of a film obtained by using CrOCN (Cr:O:C:N=51:27:5:18 atomic % ratio). Furthermore, in this specification, the composition of the CrOCN film is a stoichiometric ratio, which means that the atomic number ratio is Cr:O:C:N=1:1:1:1.

The surface of the substrate 11 of the phase shift mask blank 10 is finished by grinding. On the other hand, the phase shift layer 12 is formed by sputtering. Therefore, usually the arithmetic mean height of the surface of the phase shift layer 12 is greater than the arithmetic mean height of the surface of the substrate 11. However, by making the arithmetic mean height of the surface of the phase shift layer 12 only greater than the arithmetic mean height of the substrate 11 by a predetermined value, it can be achieved. The adhesion of the photoresist pattern formed in this phase shift mask blank becomes good. For example, this effect is obtained by making the arithmetic mean height of the surface of the phase shift layer 12 greater than the arithmetic mean height of the surface of the substrate 11 by more than 0.04 nm. From the viewpoint of scattering of exposure light in the surface of the phase shift layer 12 , the upper limit of the difference between the arithmetic mean height of the surface of the phase shift layer 12 and the arithmetic mean height of the surface of the substrate 11 is preferably set to 1.0 nm. .

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

(Modification 1)

In the above embodiment, 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 arithmetic mean height of the surface of the phase shift layer 12 is within a predetermined range. However, instead of adjusting the oxygen flow rate introduced into the sputtering chamber, after the phase shift layer 12 is formed, the surface of the phase shift layer 12 is dry-processed. Etching or wet etching creates surface irregularities with a given arithmetic mean height. 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 blank 10 described in the above embodiments and modifications can be used as a phase shift mask blank for manufacturing a phase shift mask for display device manufacturing, semiconductor manufacturing, and printed circuit board manufacturing. Furthermore, when a phase shift mask blank is used to produce a phase shift mask for display device manufacturing, a substrate having a size of 520 mm×800 mm or more can be used as the substrate 11 . In addition, the thickness of the substrate 11 can be 8~21mm.

(exposure device)

Next, as an application example of the phase shift mask produced using the phase shift mask blank 10 produced in Embodiments 1 and 2, the photolithography step of semiconductor manufacturing or liquid crystal panel manufacturing will be described with reference to FIG. 5 . The exposure device 500 is equipped with a phase shift mask 513 produced using the phase shift mask blank 10 produced in Examples 1 and 2. Furthermore, the photosensitive substrate 515 coated with the photoresist is mounted in the exposure device 500 .

The exposure device 500 includes a light source LS, an illumination optical system 502, a mask support base 503 that holds a phase shift mask 513, a projection optical system 504, an exposure object support plate 505 that holds a photosensitive substrate 515 that is an exposure object, and a user. A driving mechanism 506 for moving the exposure object support plate 505 in a horizontal plane. The exposure light emitted from the light source LS of the exposure device 500 enters the illumination optical system 502 , is adjusted to a predetermined light beam, and irradiates the phase shift mask 513 held by the mask support 503 . The light passing through the phase shift mask 513 has an image of the element pattern drawn by the phase shift mask 513, and the light is irradiated to a predetermined position of the photosensitive substrate 515 held by the exposure object support plate 505 through the projection optical system 504. Thereby, the image of the device pattern of the phase shift mask 513 can be image-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.

Various embodiments and modifications have been described above, but the present invention is not limited to these. Other aspects studied within the scope of the technical idea of the present invention are also included in the scope of the present invention.

The invention content of the following priority basic application is incorporated herein by reference.

Japanese Patent Application 2018 No. 172898 (filed on September 14, 2018)

10: Phase shift mask blank

11:Substrate

12: Phase shift layer

12a: Concave and convex parts

Claims (42)

A phase shift mask blank, which has a substrate and a phase shift layer formed on the substrate, and is used to form a mask with a predetermined pattern through wet etching. The arithmetic mean height of the surface of the phase shift layer is 0.38. nm and above. A phase shift mask blank, which has a substrate and a phase shift layer formed on the substrate. The arithmetic mean height of the surface of the phase shift layer is more than 0.38 nm. The phase shift layer contains chromium and oxygen and does not contain silicon. . The phase shift mask blank according to claim 1 or 2, wherein the arithmetic mean height of the surface of the phase shift layer is 0.402 nm or more. The phase shift mask blank according to claim 1 or 2, wherein the arithmetic mean height of the surface of the phase shift layer is greater than the arithmetic mean height of the surface of the substrate by more than 0.04 nm. The phase shift mask blank according to claim 2, wherein the phase shift mask blank is used to form a mask with a predetermined pattern through wet etching. A phase-shift mask blank, which has a substrate and a phase-shift layer formed on the substrate, and is used to form a mask with a predetermined pattern through wet etching. The arithmetic mean height of the surface of the phase-shift layer is greater than the above-mentioned The value of the arithmetic mean height of the surface of the substrate is greater than 0.04nm. A phase-shift mask blank, which has a substrate and a phase-shift layer formed on the substrate. The arithmetic mean height of the surface of the phase-shift layer is greater than the arithmetic mean height of the surface of the substrate by more than 0.04 nm. The above-mentioned The phase shift layer contains chromium and oxygen, but does not contain silicon. The phase shift mask blank according to claim 1 or 6, wherein the phase shift layer contains chromium and oxygen. The phase shift mask blank according to claim 8, wherein the phase shift layer does not contain silicon. The phase shift mask blank according to any one of claims 1, 2, 6, and 7, wherein the phase shift layer is composed of CrOCN, and the oxygen atomic number concentration in CrOCN is higher than the stoichiometric ratio. The phase shift mask blank according to any one of claims 1, 2, 6, and 7, wherein the oxygen atom number concentration of the phase shift layer at a depth of 1.25 nm from the surface is 42.6% or more. The phase shift mask blank according to any one of claims 1, 2, 6, and 7, wherein the oxygen atom number concentration on the surface side of the phase shift layer is greater than the oxygen atom number concentration on the substrate side. The phase shift mask blank according to any one of claims 1, 2, 6, and 7, wherein the oxygen atom number concentration at a depth of 1.25 nm from the surface of the phase shift layer is relative to the distance of the phase shift layer The ratio of oxygen atomic number concentration at a depth of 85 nm on the surface is 1.59 or more. A phase shift mask blank, which has a substrate and a phase shift layer formed on the substrate, and is used to form a mask with a predetermined pattern through wet etching. The phase shift layer contains chromium and oxygen, and the phase shift layer contains The oxygen atomic number concentration on the surface side is greater than the oxygen atomic number concentration on the substrate side of the phase shift layer. A phase shift photomask blank, which has a substrate and a phase shift layer formed on the substrate. The phase shift layer contains chromium and oxygen and does not contain silicon. The oxygen atom number concentration on the surface side of the phase shift layer is greater than the phase shift layer. The concentration of oxygen atoms on the substrate side of the layer. The phase shift mask blank according to claim 14 or 15, wherein, The above-mentioned phase shift layer is composed of CrOCN, and the concentration of oxygen atoms in CrOCN is higher than the stoichiometric ratio. The phase shift mask blank according to claim 14 or 15, wherein the oxygen atom concentration at a depth of 1.25 nm from the surface of the phase shift layer is above 42.6%. The phase shift mask blank according to claim 14 or 15, wherein the number concentration of oxygen atoms at a depth of 1.25 nm from the surface of the phase shift layer is relative to the number of oxygen atoms at a depth of 85 nm from the surface of the phase shift layer. The ratio of number concentration is 1.59 or more. The phase shift mask blank according to claim 15, wherein the phase shift mask blank is used to form a mask with a predetermined pattern through wet etching. The phase shift mask blank according to any one of claims 1, 2, 6, 7, 14, and 15, wherein the size of the above-mentioned substrate is 520mm×800mm or more. A phase shift mask in which the phase shift layer of the phase shift mask blank according to any one of claims 1 to 20 is formed into a predetermined pattern. An exposure method, which is to expose a photosensitive substrate coated with a photoresist through a phase shift mask as claimed in claim 21. A manufacturing method of an element, which includes: an exposure step of exposing the above-mentioned photosensitive substrate by the exposure method according to claim 22; and a development step of developing the exposed photosensitive substrate. A method for manufacturing a phase shift mask blank, which includes a film forming step of forming a phase shift layer on a substrate. In the film forming step, when the phase shift layer is formed on the substrate, a film is introduced into The oxygen concentration in the sputtering chamber where the film is formed on the substrate changes, and the phase shift layer is formed on the substrate such that the arithmetic mean height of the surface of the phase shift layer is 0.38 nm or more. The manufacturing method of phase shift mask blank as described in claim 24, wherein, In the above film forming step, the above phase shift layer containing chromium and oxygen is formed into a film. The method for manufacturing a phase shift mask blank according to claim 25, wherein in the above film forming step, the above phase shift layer that does not contain silicon is formed into a film. The method for manufacturing a phase shift mask blank according to any one of claims 24 to 26, wherein in the film forming step, the phase shift layer is formed on the substrate in the following manner: The oxygen atomic number concentration on the surface side is greater than the oxygen atomic number concentration on the substrate side of the phase shift layer. The method for manufacturing a phase shift mask blank according to any one of claims 24 to 26, wherein in the film forming step, a first gas inlet and a second gas are used to introduce gas into the sputtering chamber. The inlet is used to form the phase shift layer on the substrate conveyed by the conveying unit, and the first gas inlet is disposed upstream of the substrate conveyed by the conveying unit with respect to the second gas inlet. The method of manufacturing a phase shift mask blank according to claim 28, wherein a gas with a lower oxygen concentration is introduced into the first gas inlet relative to the second gas inlet. The method for manufacturing a phase shift mask blank according to any one of claims 24 to 26, wherein in the film forming step, the phase shift layer is formed on the substrate in the following manner: The value of the arithmetic mean height of the surface is above 0.402nm. The method for manufacturing a phase shift mask blank according to any one of claims 24 to 26, wherein in the film forming step, the phase shift layer is formed on the substrate in the following manner: The value of the arithmetic mean height of the surface is greater than the value of the arithmetic mean height of the surface of the above substrate by 0.04 nm and above. A method for manufacturing a phase shift mask blank, which includes: a film forming step of forming a phase shift layer on a substrate, and a surface of the phase shift layer formed by the film forming step, using the arithmetic calculation method of the surface The etching step of wet etching or dry etching is performed such that the average height value is above 0.402nm. A method of manufacturing a phase shift mask blank. The phase shift mask blank is used to form a mask with a predetermined pattern through wet etching. The manufacturing method of the phase shift mask blank includes: forming a phase shift layer on a substrate. The film forming step, and the etching step of performing wet etching or dry etching on the surface of the phase shift layer formed by the above film forming step in such a manner that the arithmetic mean height of the surface is greater than 0.38 nm. A method for manufacturing a phase shift mask blank, which includes: a film forming step of forming a phase shift layer containing chromium and oxygen and not containing silicon on a substrate, and the above phase shift after the film is formed by the above film forming step The surface of the layer is subjected to an etching step of wet etching or dry etching in such a manner that the arithmetic mean height of the surface is above 0.38 nm. The method for manufacturing a phase shift mask blank according to claim 33 or 34, wherein in the etching step, etching is performed in the following manner: the arithmetic mean height of the surface is above 0.402 nm. The method for manufacturing a phase shift mask blank according to any one of claims 32 to 34, wherein in the above etching step, etching is performed in the following manner: the value of the arithmetic mean height of the above surface is greater than the value of the surface of the above substrate. The value of the arithmetic mean height is greater than 0.04nm. The method for manufacturing a phase shift mask blank according to claim 32 or 33, wherein in the above film forming step, the above phase shift layer containing chromium and oxygen is formed into a film. The manufacturing method of phase shift mask blank as described in claim 37, wherein, In the above film-forming step, the above-mentioned phase shift layer without silicon is formed into a film. A method for manufacturing a phase shift mask, which includes the steps of manufacturing the phase shift mask blank using the method for manufacturing a phase shift mask blank according to any one of claims 24 to 38, and forming a predetermined phase shift layer on the phase shift layer. The pattern forming steps of the pattern. The method of manufacturing a phase shift mask according to claim 39, wherein in the pattern forming step, a predetermined pattern is formed on the phase shift layer by wet etching. An exposure method in which a photosensitive substrate coated with a photoresist is exposed using a phase shift mask obtained by the manufacturing method of a phase shift mask as described in claim 39 or 40. A method of manufacturing an element, which includes: an exposure step of exposing the above-mentioned photosensitive substrate by the exposure method according to claim 41; and a development step of developing the exposed photosensitive substrate.