Phase shift mask blank and method for manufacturing phase shift mask

Abstract

The invention relates to a phase shift mask blank and a manufacturing method of a phase shift mask. The phase shift mask blank includes a phase shift film and a light shielding film formed in contact with the phase shift film and formed of a chromium-containing material, in which the phase shift film is formed of a material containing silicon and not containing carbon, the light shielding film is formed of a material containing chromium, oxygen, nitrogen, and carbon, the light shielding film has a laminated structure including four layers: a first layer, a second layer, a third layer, and a fourth layer, the first layer is a layer farthest from the transparent substrate, the fourth layer is a layer in contact with the phase shift film, the second layer is a layer comprising carbon, and the fourth layer in contact with the phase shift film is a layer not comprising carbon.

Description

TECHNICAL FIELD

[0001] The present application relates to a phase shift mask blank as a material for manufacturing a phase shift mask for semiconductor devices and the like, and a method of manufacturing a phase shift mask using the same. BACKGROUND

[0002] In recent years, with miniaturization of semiconductor devices, particularly high integration of large scale integrated circuits, a high pattern resolution is required for projection exposure. Therefore, for a photomask, a phase shift method has been developed as a method for improving the resolution of a transferred pattern. The principle of the phase shift method is to adjust the phase of transmitted light through an opening of a mask pattern (a phase shift film pattern) to be inverted by about 180 degrees with respect to the phase of transmitted light through an adjacent portion to the opening, thereby reducing light intensity at a boundary portion between the transmitted light beams when the transmitted light beams interfere with each other, as a result, the resolution and depth of focus of a transferred pattern are improved, and a photomask using this principle is called a phase shift mask.

[0003] The most common structure of a phase shift mask blank used as a phase shift mask material is that a phase shift film is laminated on a transparent substrate such as a glass substrate, and a chromium (Cr) containing film is laminated on the phase shift film. The phase shift film generally has a phase difference of about 175 to 185 degrees and a transmittance of about 6 to 30% with respect to exposure light used in a wafer exposure apparatus, and is typically formed of a film containing molybdenum (Mo) and silicon (Si). In addition, the thickness of the chromium (Cr) containing film is adjusted to a desired optical density (OD) when combined with the phase shift film, and the chromium (Cr) containing film is generally used as a light shielding film and a hard mask for etching the phase shift film.

[0004] Specifically, as a method of manufacturing a phase shift mask by forming a phase shift film pattern from a phase shift mask blank, a resist film is first formed on a chromium (Cr) containing film of the phase shift mask blank, a pattern is drawn on the resist film with light or an electron beam and developed to form a resist pattern, and the chromium (Cr) containing film is etched using the resist pattern as an etching mask to form a pattern of the chromium (Cr) containing film. Next, the phase shift film is etched using the pattern of the chromium (Cr) containing film as an etching mask to form a phase shift film pattern. Next, the resist pattern is removed with a sulfuric acid containing aqueous solution, such as a sulfuric acid / hydrogen peroxide solution (a mixed solution of sulfuric acid and hydrogen peroxide). In addition, the film surface is cleaned with an aqueous solution containing an alkaline substance such as ammonia (NH3) to neutralize the film surface, and then the pattern of the chromium (Cr) containing film is removed by etching.

[0005] When the pattern of the chromium (Cr) -containing film is removed, generally, the light shielding film remains outside the area where the circuit pattern is formed by the phase shift film pattern, and the remaining light shielding film functions as a light shielding portion (light shielding film pattern) at the outer peripheral edge portion of the phase shift mask in a manner that the total optical density (OD) of the phase shift film and the light shielding film is generally 3 or more. This is to prevent unnecessary exposure light from leaking and irradiating the resist film on the adjacent chip located outside the circuit pattern when the circuit pattern is transferred to the wafer using a wafer exposure apparatus. As a method of forming such a light shielding portion, the phase shift film pattern is generally formed, the resist pattern is removed, and then the resist film is reformed. The chromium (Cr) -containing film is etched in the circuit pattern portion of the phase shift film pattern using the resist pattern formed by drawing and developing the pattern as an etching mask, so that the light shielding portion is left at the outer peripheral edge portion.

[0006] For the phase shift mask requiring high-precision pattern formation, dry etching using a gas plasma is mainly used as etching. Dry etching using a chlorine (Cl) -based gas containing oxygen (O) (chlorine (Cl) -based dry etching) is used for dry etching of the chromium (Cr) -containing film, and dry etching using a fluorine (F) -based gas is used for dry etching of the molybdenum (Mo) and silicon (Si) -containing film. In particular, it is known that when the chromium (Cr) -containing film is dry etched, the chemical reactivity is enhanced and the etching rate is improved by using an etching gas obtained by mixing 10 to 25% by volume of oxygen (O2 gas) with the chlorine (Cl) -based gas.

[0007] As the circuit pattern becomes finer, for the phase shift mask, a technique for forming a fine phase shift film pattern is also required. In particular, when the circuit pattern is transferred to the wafer using a wafer exposure apparatus, it is required to form the line pattern of the auxiliary pattern of the resolution of the main pattern of the auxiliary phase shift mask smaller than the main pattern so as not to be transferred to the wafer. In a one-generation phase shift mask in which the line and space pattern of the main pattern has a pitch of 10 nm in the circuit pattern on the wafer, it is required that the line and space pattern of the auxiliary pattern on the phase shift mask has a line width of about 40 nm.

[0008] On the other hand, a chemically amplified resist for forming a mask pattern such as a phase shift film pattern includes a base resin, an acid generator, a surfactant, and the like, and can be used in many reactions in which the acid generated by exposure serves as a catalyst, so that high sensitivity can be achieved. The chemically amplified resist makes it possible to form a mask pattern such as a fine phase shift film pattern having a line width of 200 nm or less. However, even in the chemically amplified resist, if the pattern width is narrow, the fine line pattern collapses due to the collision of the developer in the developing process, and the resolution limit is reached.

[0009] As to thinning of the resist film, for example, in the method described in WO 2010 / 038445 (Patent Document 1), in order to form a fine pattern, a film containing molybdenum (Mo) and silicon (Si) which can be thinned is formed as a film for forming a mask pattern, and an etching mask film which is a film containing chromium and carbon, for example, a film made of chromium oxynitride, having a high etching rate is formed thereon, whereby the resist film is thinned and collapse of the resist pattern is reduced.

[0010] In etching using a resist film (resist pattern), during the etching process, the resist pattern is also etched to some extent, and if the resist pattern disappears, a defect such as a pinhole appears in the film under the resist pattern (on the transparent substrate side). Therefore, it is necessary to set the thickness of the resist film so that the resist pattern remains at a predetermined thickness after etching. In the method described in WO 2010 / 038445 (Patent Document 1), the film for forming a mask pattern is a molybdenum (Mo)-containing film, and the etching mask film is a film containing chromium and carbon, which has a relatively fast etching rate and can be thinned, so that the time for etching the chromium-containing film can be shortened, and the resist film can be thinned, further reducing line edge roughness (LER).

[0011] Bibliographic details

[0012] Patent Document 1: WO 2010 / 038445

[0013] Patent Document 2: JP-A 2008-51880 SUMMARY

[0014] For a photomask used in a manufacturing process of an advanced semiconductor device, a protective member called a pellicle is used to prevent pattern transfer failure due to attachment of foreign matter. The pellicle includes a transparent film that transmits exposure light and a frame for connecting the transparent film. By connecting the pellicle to the photomask, it is possible to prevent foreign matter from adhering to the surface of the photomask. However, even in a photomask to which a pellicle is connected, there is a problem that foreign matter called haze (grown foreign matter) is generated on the surface of the photomask due to accumulation of the amount of exposure light, thereby causing pattern transfer failure. In the process of manufacturing an advanced semiconductor device, since the circuit pattern is fine, the exposure light currently used has been changed from KrF excimer laser light having a wavelength of 248 nm to ArF excimer laser light having a shorter wavelength of 193 nm. However, the higher the energy (the shorter the wavelength of the exposure light), the more obvious the occurrence of haze.

[0015] If haze appears on a photomask, since the haze becomes an obstacle (defect) to exposure light, a desired pattern cannot be formed on a wafer having the photomask on which the haze appears. If the haze has appeared, it is necessary to remove the resist once and clean the photomask to remove the haze. Furthermore, it is also necessary to confirm that the haze is completely removed after cleaning using a photomask pattern inspection apparatus, and the generation of the haze greatly reduces the productivity in a process of manufacturing a semiconductor device.

[0016] In particular, in the manufacture of a memory-based device, a single photomask is used to expose 100,000 or more wafers. Therefore, the photomask used in the manufacture of a memory-based device has a larger cumulative exposure amount of exposure light than the photomask used in the manufacture of a logic-based device. In wafer exposure for manufacturing a semiconductor device, in the case where the exposure light is an ArF excimer laser, the light amount of the exposure light irradiated in one exposure is 10 to 20 mJ / cm 2 . At the same time, the circuit pattern of the photomask is exposed to a single wafer a plurality of times. Therefore, if a single photomask is used to expose 100,000 or more wafers, the cumulative amount of exposure light irradiated to the photomask is several tens of kJ / cm 2 .

[0017] One of the causes of the haze is considered to be that sulfate ions (SO4 2- ) contained in an acid substance contained in a sulfuric acid aqueous solution used for cleaning to peel off a resist pattern in the process of manufacturing a photomask, and furthermore, basic ions (for example, ammonium ions (NH4 + ) in the case where the basic substance is ammonia (NH3)) contained in an aqueous solution containing a basic substance such as ammonia (NH3) used to neutralize the surface of the film thereafter are left on the surface of the film, and when irradiated with exposure light, the sulfate ions and the basic ions react with each other to form a salt (for example, ammonium sulfate ((NH4)2SO4)), and furthermore, the salt grows into a solid (particulate) by the accumulation of the irradiation amount of the exposure light (see, for example, JP-A-2008-51880 (Patent Document 2)).

[0018] The present application was made to solve the above problems, and aims to provide a phase shift mask blank capable of thinning a resist film, and to provide a phase shift mask in which the haze appearing when the irradiation amount of exposure light is accumulated is suppressed, and to provide a method of manufacturing a phase shift mask from the phase shift mask blank.

[0019] In a case where a circuit pattern is formed on a phase shift film as a film for forming a circuit pattern and a chromium (Cr) -containing film is formed in contact with the circuit pattern (phase shift film pattern), even if the chromium (Cr) -containing film is removed from above the phase shift film pattern by dry etching using a chlorine (Cl) -based gas containing oxygen (O), chromium (Cr) can remain on the surface of the phase shift film pattern. If chromium (Cr) remains on the surface of the phase shift film pattern, the chromium (Cr) reacts and becomes a chromium (Cr) compound such as chromium oxide (CrO) when irradiated with exposure light. The chromium (Cr) compound such as chromium oxide (CrO) further grows into a solid (particulate), causing haze.

[0020] In particular, in a case where the phase shift film contains a transition metal such as molybdenum (Mo) and the chromium (Cr) -containing film contains carbon (C), the transition metal such as molybdenum (Mo) and the carbon (C) react with each other at the interface between the two films, forming a transition metal carbide such as molybdenum carbide (MoC). The transition metal carbide having a high melting point and a high hardness is difficult to etch by dry etching using a chlorine (Cl) -based gas containing oxygen (O), and is also difficult to remove by cleaning.

[0021] In particular, molybdenum carbide (MoC) is difficult to etch by dry etching using a chlorine (Cl) -based gas containing oxygen (O), and thus is difficult to completely remove. As a result, after the phase shift film pattern is formed, a transition metal carbide such as molybdenum carbide (MoC) remains on the phase shift film pattern in which chromium (Cr) is introduced, and a chromium (Cr) compound such as chromium oxide (CrO) derived from chromium (Cr) causes significant haze. In this case, due to accumulation of the amount of irradiation of exposure light, the chromium (Cr) compound such as chromium oxide (CrO) not only spreads on the phase shift film pattern (line pattern), but also spreads to a space pattern (a portion in which no circuit pattern is present, for example, on a transparent substrate) adjacent to the phase shift film pattern, also causing haze on the space pattern.

[0022] On the other hand, in a case where the phase shift film contains silicon (Si) and the chromium (Cr) -containing film contains carbon (C), silicon (Si) and carbon (C) react with each other at an interface between the two films, forming silicon carbide (SiC). In this case, when the phase shift film pattern is formed and the chromium (Cr) -containing film is removed from above the phase shift film pattern by dry etching using a chlorine (Cl) -based gas containing oxygen (O) in a process of manufacturing the phase shift mask, silicon carbide (SiC) is hardly etched by dry etching using the chlorine (Cl) -based gas containing oxygen (O), and thus silicon carbide (SiC) remains on a surface portion of the phase shift film pattern. Since silicon carbide (SiC) is easily dissolved in an aqueous solution containing sulfuric acid, when the aqueous solution containing sulfuric acid, which is used for removing a resist film for forming a light-shielding portion (light-shielding film pattern) on a peripheral edge portion of the phase shift film and for cleaning the phase shift mask in a process of manufacturing the phase shift mask from a phase shift mask blank, comes into contact with silicon carbide (SiC) remaining on the surface portion of the phase shift film pattern, silicon carbide (SiC) is dissolved and removed, and the optical properties (phase difference, transmittance, etc.) of the phase shift film pattern change.

[0023] As a result of intensive studies to solve the above-described problems, the present inventors have achieved the present application, finding that if a phase shift mask blank includes a phase shift film formed of a material containing silicon (Si) and not containing carbon (C) and a light-shielding film formed in contact with the phase shift film and formed of a chromium (Cr) -containing material, the phase shift mask blank is capable of thinning a resist film used in manufacturing a phase shift mask, wherein the light-shielding film has a layered structure including, in order from a side distal from a transparent substrate, four layers of a first layer, a second layer, a third layer, and a fourth layer, or four layers of a first layer, a third layer, a second layer, and a fourth layer, the first layer being a layer distal from the transparent substrate, the fourth layer being a layer in contact with the phase shift film, and in the layered structure, the second layer is a layer containing carbon (C), the fourth layer is a layer not containing carbon (C), and the phase shift mask obtained from the phase shift mask blank is a phase shift mask in which almost no haze occurs and the optical properties of the phase shift film are hardly changed even when the phase shift film is cleaned with an aqueous solution containing sulfuric acid.

[0024] Therefore, the present application provides a phase shift mask blank and a method of manufacturing a phase shift mask as follows.

[0025] 1. A phase shift mask blank, comprising:

[0026] a transparent substrate;

[0027] a phase shift film provided on the transparent substrate and formed of a material containing silicon (Si) and not containing carbon (C); and

[0028] a light shielding film provided on a side of the phase shift film distal from the transparent substrate and formed of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C),

[0029] wherein the light shielding film has a layered structure including, in order from the side distal from the transparent substrate, four layers of a first layer, a second layer, a third layer, and a fourth layer, or four layers of a first layer, a third layer, a second layer, and a fourth layer,

[0030] In the layered structure, the first layer is a layer most distal from the transparent substrate, and the fourth layer is a layer in contact with the phase shift film,

[0031] the first layer contains chromium (Cr) and oxygen (O), the chromium (Cr) content is 28 atomic% or more and 40 atomic% or less, the oxygen (O) content is 47 atomic% or more and 60 atomic% or less, and the thickness of the first layer is 1 nm or more and 4 nm or less,

[0032] the second layer contains chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), the chromium (Cr) content is 30 atomic% or more and 45 atomic% or less, the oxygen (O) content is 28 atomic% or more and 40 atomic% or less, the nitrogen (N) content is 12 atomic% or more and 24 atomic% or less, and the carbon (C) content is 5 atomic% or more and 15 atomic% or less, and the second layer has a thickness of 18 nm or more and 24 nm or less,

[0033] the third layer contains chromium (Cr) and nitrogen (N), the chromium (Cr) content is 50 atomic% or more and 60 atomic% or less, the nitrogen (N) content is 20 atomic% or more and 40 atomic% or less, and the thickness of the third layer is 1 nm or more and 6 nm or less, and

[0034] the fourth layer contains chromium (Cr), oxygen (O), and nitrogen (N), and does not contain carbon (C), the chromium (Cr) content is 35 atomic% or more and 44 atomic% or less, the oxygen (O) content is 42 atomic% or more and 54 atomic% or less, and the nitrogen (N) content is 2 atomic% or more and 20 atomic% or less, and the fourth layer has a thickness of 18 nm or more and 36 nm or less.

[0035] 2. The phase shift mask blank according to 1, wherein the phase shift film has a zeta potential of -15 mV or more and +15 mV or less at a pH of 3 or more and 4 or less, and a zeta potential of -60 mV or more and +10 mV or less at a pH of 5 or more and 6 or less.

[0036] 3. The phase shift mask blank according to 1, wherein

[0037] the first layer contains nitrogen (N), and the nitrogen (N) content is 5 atomic% or more and 25 atomic% or less, and

[0038] The third layer contains oxygen (O) at a content of 6 atomic % or more and 30 atomic % or less.

[0039] 4. The phase shift mask blank according to 1, wherein the material forming the phase shift film contains nitrogen (N).

[0040] 5. The phase shift mask blank according to 1, wherein the material forming the phase shift film does not contain a transition metal.

[0041] 6. The phase shift mask blank according to 1, wherein the total sheet resistance of the first layer, the second layer, the third layer, and the fourth layer of the light shielding film is 350 kΩ / □ or less.

[0042] 7. The phase shift mask blank according to 1, wherein the phase shift film has a phase difference of 175 degrees or more and 185 degrees or less and a transmittance of 6% or more and 30% or less with respect to ArF excimer laser light (wavelength 193 nm), and the phase shift film has a thickness of 60 nm or more and 85 nm or less.

[0043] 8. The phase shift mask blank according to 1, wherein the total optical density (OD) of the phase shift film and the light shielding film with respect to ArF excimer laser light (wavelength 193 nm) exposure light is 3 or more.

[0044] 9. The phase shift mask blank according to 8, wherein the light shielding film has a thickness of 48 nm or more and 54 nm or less.

[0045] 10. A method for manufacturing a phase shift mask having a circuit pattern of a phase shift film from the phase shift mask blank according to any one of 1 to 9, the method comprising:

[0046] (A) forming a first resist film on a light shielding film;

[0047] (B) forming a first resist pattern by patterning the first resist film;

[0048] (C) forming a light shielding film pattern by patterning the light shielding film by dry etching using a chlorine (Cl) -based gas containing oxygen (O) using the first resist pattern as an etching mask;

[0049] (D) forming a phase shift film pattern by patterning the phase shift film by dry etching using a fluorine (F) -based gas using the light shielding film pattern as an etching mask;

[0050] (E) removing the first resist pattern;

[0051] (F) forming a second resist film on the light shielding film pattern;

[0052] (G) A second resist pattern is formed on the outer peripheral edge portion outside the area where the circuit pattern of the phase-shifting film is formed by patterning the second resist film;

[0053] (H) Using a second resist pattern as an etching mask, the light-shielding film pattern is removed in the area of ​​the circuit pattern forming the phase-shifting film by dry etching with an oxygen-containing (O) chlorine (Cl)-based gas; and

[0054] (I) Remove the second resist pattern.

[0055] Beneficial effects of the present invention

[0056] According to the phase shift mask blank of the present invention, the resist film used in manufacturing the phase shift mask can be made thinner, and a phase shift mask such that when the phase shift film is cleaned with an aqueous solution containing sulfuric acid, almost no haze appears and the optical properties of the phase shift film remain almost unchanged. Attached Figure Description

[0057] Figure 1 This is a cross-sectional view showing an example of the phase-shifting mask blank of the present invention;

[0058] Figure 2 This is a cross-sectional view illustrating an example of the phase-shifting mask of the present invention;

[0059] Figure 3 This is a cross-sectional view illustrating another example of the phase-shifting mask blank of the present invention; and

[0060] Figure 4 This is a cross-sectional view illustrating another example of the phase-shifting mask of the present invention. Detailed Implementation

[0061] The present invention will now be described in more detail.

[0062] The phase-shifting mask blank of the present invention includes a transparent substrate, a phase-shifting film disposed on the transparent substrate, and a light-shielding film disposed in contact with the phase-shifting film on a side of the phase-shifting film away from the transparent substrate. The light-shielding film has a stacked structure, which includes, from the side away from the transparent substrate, four layers in sequence: a first layer, a second layer, a third layer, and a fourth layer, or four layers in sequence: a first layer, a third layer, a second layer, and a fourth layer.

[0063] The phase-shift mask blank of the present invention can be used to manufacture a phase-shift mask having a circuit pattern (phase-shift film pattern) of a phase-shift film on a transparent substrate. In particular, the phase-shift mask blank of the present invention is suitable for manufacturing a phase-shift mask having a light-shielding portion (light-shielding film pattern) at the outer peripheral edge of the phase-shift mask, the light-shielding portion being formed by a light-shielding film that contacts the phase-shift film outside the area (effective area) where the circuit pattern of the phase-shift film is formed.

[0064] The phase shift mask blank and the phase shift mask of the present application are suitable as a phase shift mask blank and a phase shift mask using light having a wavelength of 200 nm or less, such as an ArF excimer laser (wavelength 193 nm), as exposure light.

[0065] Hereinafter, the phase shift mask blank and the phase shift mask of the present application will be described with reference to the drawings, the same elements are denoted by the same reference numerals, and the description thereof will be omitted. In addition, the drawings can be shown in an exaggerated manner for convenience, and the dimensional ratio between the elements is not necessarily the same as that in actuality.

[0066] Figure 1 is a cross-sectional view showing one example of the phase shift mask blank of the present application. The phase shift mask blank 101 includes a transparent substrate 1, a phase shift film 2 provided on the transparent substrate 1, and a light shielding film 3 provided in contact with the phase shift film 2 on a side of the phase shift film 2 distal from the transparent substrate 1. The light shielding film 3 has a layered structure 30 including four layers: a first layer 31, a second layer 32, a third layer 33, and a fourth layer 34 in this order from the side distal from the transparent substrate 1.

[0067] Figure 2 The phase shift mask shown can be manufactured from the phase shift mask blank shown. Figure 1 Figure 2 is a cross-sectional view showing one example of the phase shift mask of the present application. The phase shift mask 102 includes a transparent substrate 1, a phase shift film pattern 2a provided on the transparent substrate 1, and a light shielding film pattern 3a provided in contact with the phase shift film pattern 2a in a portion located at a peripheral edge portion of a main surface of the transparent substrate 1 on a side of the phase shift film pattern 2a distal from the transparent substrate 1, a circuit pattern being formed in an effective region 4. The light shielding film pattern 3a has a layered structure 30 including four layers: a first layer 31, a second layer 32, a third layer 33, and a fourth layer 34 in this order from the side distal from the transparent substrate 1.

[0068] In the phase shift mask blank and the phase shift mask of the present application, Figure 1 and Figure 2 In the phase shift mask blank and the phase shift mask of the present application, the first layer 31 is a layer in contact with the second layer 32 and most distal from the transparent substrate 1. The second layer 32 is a layer in contact with the first layer 31 and the third layer 33. The third layer 33 is a layer in contact with the second layer 32 and the fourth layer 34. The fourth layer 34 is a layer in contact with the third layer 33 and the phase shift film 2.

[0069] Figure 3 is a cross-sectional view showing another example of the phase shift mask blank of the present application. The phase shift mask blank 103 includes a transparent substrate 1, a phase shift film 2 provided on the transparent substrate 1, and a light shielding film 3 provided in contact with the phase shift film 2 on a side of the phase shift film 2 distal from the transparent substrate 1. The light shielding film 3 has a layered structure 30 including four layers: a first layer 31, a third layer 33, a second layer 32, and a fourth layer 34 in this order from the side distal from the transparent substrate 1.​

[0070] Figure 4 The phase shift mask shown can be manufactured from a phase shift mask blank shown. Figure 3 The phase shift mask blank shown is manufactured. Figure 4 is a cross-sectional view showing another example of the phase shift mask of the present application. The phase shift mask 104 includes a transparent substrate 1, a phase shift film pattern 2a provided on the transparent substrate 1, and a light shielding film pattern 3a provided in contact with the phase shift film pattern 2a in a portion located at an outer peripheral edge portion of a main surface of the transparent substrate 1 on a side distal from the transparent substrate 1, a circuit pattern being formed in an effective region 4. The light shielding film pattern 3a has a laminated structure 30 including four layers: a first layer 31, a third layer 33, a second layer 32, and a fourth layer 34 in this order from the side distal from the transparent substrate 1.

[0071] In the phase shift mask blank shown in FIG. 1, the first layer 31 is a layer in contact with the third layer 33 and most distal from the transparent substrate 1. The third layer 33 is a layer in contact with the first layer 31 and the second layer 32. The second layer 32 is a layer in contact with the third layer 33 and the fourth layer 34. The fourth layer 34 is a layer in contact with the second layer 32 and the phase shift film 2. Figure 3 and Figure 4 In the phase shift mask blank shown in FIG. 1, the first layer 31 is a layer in contact with the third layer 33 and most distal from the transparent substrate 1. The third layer 33 is a layer in contact with the first layer 31 and the second layer 32. The second layer 32 is a layer in contact with the third layer 33 and the fourth layer 34. The fourth layer 34 is a layer in contact with the second layer 32 and the phase shift film 2.

[0072] The kind and size of the transparent substrate are not particularly limited as long as it is transparent at a wavelength used as an exposure wavelength, for example, a quartz substrate such as a synthetic quartz substrate is used. As the transparent substrate, for example, a substrate having a size of 6 inches square and a thickness of 0.25 inch (referred to as a 6025 substrate) defined by SEMI standards is suitable. When the SI unit system is used, the size of the 6025 substrate is generally described as 152 square millimeters and 6.35 millimeters thick.

[0073] In the present application, the phase shift film can be formed in contact with the transparent substrate, or can be formed on the transparent substrate via one or more other films. The phase shift film can be a single layer film, a multi-layer film (for example, a film including two layers, three layers, or four layers), or a film having a gradient composition.

[0074] Preferably, the phase shift film is a half-tone phase shift film. In the case where the phase shift film is a half-tone phase shift film, the phase shift mask blank is a half-tone phase shift mask blank, and the phase shift mask is a half-tone phase shift mask.

[0075] The phase shift film is formed of a material containing silicon (Si) and not containing carbon (C). The material containing silicon (Si) and not containing carbon (C) preferably contains one or both of oxygen (O) and nitrogen (N), particularly nitrogen (N). The material containing silicon (Si) and not containing carbon (C) of the phase shift film can contain hydrogen (H).

[0076] The silicon (Si) -containing and carbon (C) -free material of the phase shift film can be a silicon (Si) compound containing silicon (Si) and one or both of oxygen (O) and nitrogen (N). Specific examples of the silicon (Si) compound include a material consisting of silicon (Si) and nitrogen (N) (silicon nitride (SiN) ), and a material consisting of silicon (Si), oxygen (O) and nitrogen (N) (silicon oxynitride (SiON) ).

[0077] The silicon (Si) -containing and carbon (C) -free material is preferably free of chromium (Cr). The silicon (Si) -containing and carbon (C) -free material can contain a transition metal other than chromium (Cr). In the case where the material contains a transition metal other than chromium (Cr), the content of the transition metal other than chromium (Cr) is preferably always 6 atomic % or less, more preferably 4 atomic % or less.

[0078] In addition, in the case where the material contains a transition metal (Me) other than chromium (Cr), the silicon (Si) -containing and carbon (C) -free material of the phase shift film can be a transition metal silicon (MeSi) compound containing the transition metal (Me) and silicon (Si), or contain the transition metal (Me), silicon (Si), and one or both of nitrogen (N) and oxygen (O). Specific examples of the transition metal silicon (MeSi) compound include a material consisting of the transition metal (Me), silicon (Si), nitrogen (N) (transition metal silicon nitride (MeSiN) ), and a material consisting of the transition metal (Me), silicon (Si), oxygen (O) and nitrogen (N) (transition metal silicon oxynitride (MeSiON) ).

[0079] Examples of the transition metal (Me) other than chromium (Cr) include molybdenum (Mo), tungsten (W), tantalum (Ta), titanium (Ti), zirconium (Zr) and hafnium (Hf).

[0080] The silicon (Si) -containing and carbon (C) -free material is preferably free of a transition metal. If the silicon (Si) -containing and carbon (C) -free material forming the phase shift film is free of a transition metal, even if carbon (C) reaches the interface between the phase shift film and the light shielding film from the light shielding film containing carbon (C) and chromium (Cr), the carbon (C) does not react with the transition metal at the interface between the phase shift film and the light shielding film, so that a transition metal carbide is not formed. Therefore, after the light shielding film is removed from above the phase shift film pattern, a transition metal carbide such as molybdenum carbide (MoC) is not left because of the incorporation of chromium (Cr) therein, so that haze occurring if a transition metal carbide such as molybdenum carbide (MoC) is left because of the incorporation of chromium (Cr) therein is suppressed.

[0081] The phase shift film is preferably formed of a material which is resistant to dry etching using an oxygen (O) -containing chlorine (Cl) -based gas and can be removed by dry etching using a fluorine (F) -based gas.

[0082] In this invention, dry etching using a chlorine (Cl)-based gas containing oxygen (O) can typically be dry etching using a mixture of chlorine (Cl2 gas) and oxygen (O2 gas) (e.g., a gas obtained by mixing 10-25 vol% oxygen (O2 gas) and chlorine (Cl2 gas). On the other hand, in this invention, dry etching using a fluorine (F)-based gas can typically be dry etching using a gas containing carbon tetrafluoride (CF4 gas) or sulfur hexafluoride (SF6 gas).

[0083] In this invention, the zeta potential of the phase-shifting membrane is preferably within a predetermined range. The zeta potential is an indicator of the degree of charge (charge accumulation) on the surface layer of the membrane. When the zeta potential is zero (0), the number of protons (hydrogen cations) on the membrane surface layer is equal to the charge in the membrane, which is an electroneutrally neutral state. On the other hand, when the zeta potential is negative (-), there are fewer protons on the membrane surface layer compared to the charge in the membrane, which is an electronegative state; and when the zeta potential is positive (+), there are more protons on the membrane surface layer compared to the charge in the membrane, which is an electroneutrally positive state.

[0084] In this invention, preferably, the phase-shifting film has a zeta potential within a predetermined range at a pH of 3 or higher and 4 or lower. In the phase-shifting mask manufacturing process, an aqueous solution containing sulfuric acid, such as a sulfuric acid / hydrogen peroxide solution (typically with a pH of 4 or lower), is typically used to strip the resist pattern. However, when the zeta potential of the phase-shifting film approaches electroneutrality at a pH of 3 or higher and 4 or lower, the sulfate ions (SO42-) contained in the sulfuric acid-containing aqueous solution... 2- It is unlikely that sulfate ions (SO4) will be attracted to the surface of the membrane, therefore... 2- It is unlikely that residues will remain on the surface of the phase-shifting film. In particular, the advantage of phase-shifting films formed from materials containing silicon (Si) and free of transition metals is that the zeta potential is close to electroneutrality at pH values ​​above 3 and below 4.

[0085] Specifically, at a pH of 3 or higher and 4 or lower, the zeta potential of the phase-shifting membrane is preferably -15 mV or higher, more preferably -10 mV or higher, even more preferably +15 mV or lower, and more preferably +10 mV or lower.

[0086] Furthermore, in this invention, it is preferable that the phase-shifting film has a zeta potential within a predetermined range at a pH of 5 or higher and 6 or lower. In the phase-shifting mask manufacturing process, after stripping the resist pattern using an aqueous solution containing sulfuric acid, such as sulfuric acid / hydrogen peroxide solution, an aqueous solution containing ammonia (NH3) (typically having a pH of 5 or higher) is typically used to neutralize the film surface. However, when the zeta potential of the phase-shifting film at a pH of 5 or higher and 6 or lower approaches an electroweakly negative to neutral state, the ammonium (NH4+) contained in the aqueous solution containing ammonia (NH3)...+ It is unlikely that ammonium (NH4) will adhere to the membrane surface, therefore ammonium (NH4) + It is unlikely that residues will remain on the surface of the phase-shifting film. In particular, phase-shifting films formed from materials containing silicon (Si) and free of transition metals have the advantage that the zeta potential is close to the electroweak negative to neutral state at pH values ​​above 5 and below 6.

[0087] Specifically, at pH values ​​between 5 and 6, the zeta potential of the phase-shifting membrane is preferably -60 mV or higher, more preferably -30 mV or higher, more preferably +10 mV or lower, and even more preferably +5 mV or lower. As the zeta potential increases at pH values ​​between 5 and 6 (as the zeta potential approaches the positive (+) side), the ammonium (NH4)... + ) repulsion membrane surface, making ammonium (NH4) + Ammonium (NH4) is difficult to attract to the membrane surface. However, if ammonium (NH4) + If ammonium (NH4) is not attracted to the surface of the membrane, then it will not be attracted to the surface of the membrane. + It does not react with sulfate ions (SO4). 2- The reaction makes it difficult to neutralize the membrane surface. Therefore, setting an upper limit for the zeta potential as described above at a pH between 5 and 6 is effective.

[0088] By setting the zeta potential of the phase-shifting membrane at a pH of 3 or higher and 4 or lower, and setting the zeta potential of the phase-shifting membrane at a pH of 5 or higher and 6 or lower, within a predetermined range, the sulfate ions (SO42-) contained in the aqueous solution containing sulfuric acid are reduced. 2- ) and ammonium (NH4) contained in aqueous solutions containing ammonia (NH3). + It is unlikely that sulfate ions (SO42-) will remain on the surface of the phase-shifted film. As a result, when irradiated with light, sulfate ions (SO42-) are less likely to remain on the surface. 2- ) and ammonium (NH4) + The reaction between the two salts (ammonium sulfate ((NH4)2SO4)) is suppressed, and the occurrence of haze that causes the salt to grow into solid (granular) due to the cumulative exposure to light is reduced.

[0089] Preferably, the phase-shifting film has a phase difference of 175 degrees or more and 185 degrees or less with respect to the exposure light (specifically, light with a wavelength of 200 nm or less, such as ArF excimer laser (wavelength of 193 nm)). Furthermore, the transmittance of the phase-shifting film relative to the exposure light (specifically, light with a wavelength of 200 nm or less, such as ArF excimer laser (wavelength of 193 nm)) is preferably 6% or more and 30% or less, which is highly effective for improving the resolution and depth of focus of the transfer pattern based on the phase-shifting effect corresponding to the exposure conditions. From the viewpoint of setting the phase difference and transmittance within a predetermined range, the thickness of the phase-shifting film is preferably 60 nm or more, more preferably 62 nm or more, and preferably 85 nm or less, more preferably 78 nm or less.

[0090] In this invention, the light-shielding film is formed to contact the phase-shifting film. The light-shielding film can be a film with a gradient composition. The light-shielding film has a stacked structure, which sequentially includes four layers from the side away from the transparent substrate: a first layer, a second layer, a third layer, and a fourth layer, or four layers: a first layer, a third layer, a second layer, and a fourth layer. The stacked structure can include more than four layers, such as five or six layers, but preferably the stacked structure includes only four layers: a first layer, a second layer, a third layer, and a fourth layer, or four layers: a first layer, a third layer, a second layer, and a fourth layer. When the light-shielding film includes five or more layers, layers other than the first, second, third, and fourth layers are disposed at any position between the first and fourth layers in the stacked structure.

[0091] Regarding the light-shielding film, it is preferable that, in dry etching where the phase-shifting film is used as the processing film, the light-shielding film pattern formed by patterning the light-shielding film can be used as an etching mask when a phase-shifting film pattern is formed from the phase-shifting film. Therefore, the light-shielding film is preferably formed from a material that is resistant to dry etching using fluorine (F)-based gases and can be removed by dry etching using oxygen (O)-containing chlorine (Cl)-based gases.

[0092] The light-shielding film is formed from a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) throughout. By forming the light-shielding film from a carbon (C)-containing material, the etching rate of the light-shielding film during dry etching using an oxygen (O)-containing chlorine (Cl)-based gas is increased, and the time for etching the entire light-shielding film (removal time) can be shortened, while ensuring the required light-shielding properties (optical density (OD)) of the entire light-shielding film. This allows for a thinner resist film used when manufacturing a phase-shifting mask from a phase-shifting mask blank. The light-shielding film preferably does not contain silicon (Si). Furthermore, the light-shielding film preferably does not contain transition metals other than chromium (Cr).

[0093] The materials forming the first, second, third, and fourth layers of the laminated structure constituting the light-shielding film, as well as the materials forming the other layers constituting the laminated structure, contain chromium (Cr) as an essential component, and preferably also contain one or more selected from oxygen (O), nitrogen (N), and carbon (C), particularly one or two of oxygen (O) and nitrogen (N). Preferably, at least one layer selected from the first, second, and third layers, particularly the second layer, contains carbon (C). On the other hand, the fourth layer does not contain carbon (C). In addition, at least one layer selected from the first, second, and fourth layers, particularly one or two layers of the first and fourth layers, is preferably a layer with a relatively high oxygen (O) content. By configuring the first, second, third, and fourth layers in this way, the etching time (removal time) of the entire light-shielding film can be shortened when dry etching the light-shielding film using an oxygen (O)-containing chlorine (Cl)-based gas, while ensuring the required light-shielding performance (optical density (OD)) of the entire light-shielding film. Furthermore, by using a single-layer light-shielding film containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) throughout the light-shielding film, the occurrence of haze and changes in the optical properties of the phase-shifting film pattern were suppressed.

[0094] Specifically, the materials forming the first, second, third, and fourth layers of the laminated structure constituting the light-shielding film, as well as the materials forming the other layers of the laminated structure constituting the light-shielding film, can be materials composed of chromium (Cr) and oxygen (O) (chromium oxide (CrO)), materials composed of chromium (Cr) and nitrogen (N) (chromium nitride (CrN)), materials composed of chromium (Cr) and carbon (C) (chromium carbide (CrC)), materials composed of chromium (Cr), oxygen (O), and nitrogen (N) (chromium nitride (CrON)), materials composed of chromium (Cr), oxygen (O), and carbon (C) (chromium carbonoxylate (CrOC)), materials composed of chromium (Cr), nitrogen (N), and carbon (C) (chromium carbonitride (CrNC)), and materials composed of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) (chromium carbonitride (CrONC)).

[0095] Each layer of the light-shielding film can be either a light-shielding layer or an anti-reflective layer. For example, the first layer is suitable as an anti-reflective layer, and the second, third, and fourth layers are suitable as light-shielding layers.

[0096] The first layer is the layer furthest from the transparent substrate in the laminated structure. This first layer is typically the layer in contact with the photoresist film during the formation of the phase-shifting mask from the phase-shifting mask blank, and it is also the layer in direct contact with the cleaning solution. Furthermore, the first layer is the layer on which exposure light is directly incident during exposure using the phase-shifting mask. Therefore, the first layer is designed to have good adhesion to the photoresist film, high chemical resistance to the cleaning solution, and low reflectivity to exposure light.

[0097] The first layer contains chromium (Cr) and oxygen (O). The first layer preferably contains nitrogen (N). The first layer may contain a small amount of carbon (C), but preferably does not contain carbon (C). Specifically, the material forming the first layer may be a material composed of chromium (Cr) and oxygen (O), a material composed of chromium (Cr), oxygen (O) and nitrogen (N), a material composed of chromium (Cr), oxygen (O) and carbon (C), or a material composed of chromium (Cr), oxygen (O), nitrogen (N) and carbon (C), and preferably a material composed of chromium (Cr), oxygen (O) and nitrogen (N).

[0098] In the first layer, the chromium (Cr) content is preferably 28 atomic% or more, more preferably 30 atomic% or more, and preferably 40 atomic% or less, more preferably 38 atomic% or less, and even more preferably 36 atomic% or less. In the first layer, the oxygen (O) content is preferably 47 atomic% or more, more preferably 49 atomic% or more, and preferably 60 atomic% or less, more preferably 57 atomic% or less, and even more preferably 55 atomic% or less. When the first layer contains nitrogen (N), the nitrogen (N) content is greater than 0 atomic%, preferably 5 atomic% or more, more preferably 10 atomic% or more, and preferably 25 atomic% or less, more preferably 23 atomic% or less. When the first layer contains carbon (C), the carbon (C) content is preferably less than 5 atomic%, more preferably 3 atomic% or less, and even more preferably 2 atomic% or less.

[0099] The first layer can have any thickness capable of providing adhesion to the photoresist film and chemical resistance to aqueous solutions used for cleaning, and reducing the reflectivity of the light-shielding film to exposed light, and can be formed relatively thin among the first, second, third, and fourth layers. Furthermore, the thinner the first layer, the more effectively the sheet resistance reduction effect of the third layer (described later) can be achieved, thus allowing a material with relatively low conductivity (relatively high sheet resistance) to be used as the material of the first layer. The thickness of the first layer is preferably 1 nm or more, and more preferably 4 nm or less, and more preferably 3 nm or less.

[0100] The fourth layer is the layer in contact with the phase-shifting film in the stacked structure. Therefore, the fourth layer is provided as a carbon-free layer (C). By forming the fourth layer as a carbon-free (C) layer, there is no reaction between silicon (Si) and carbon (C) at the interface between the light-shielding film and the silicon (Si)-containing phase-shifting film, where such a reaction occurs in the case where the chromium (Cr)-containing light-shielding film contains carbon (C) and does not form silicon carbide (SiC). Therefore, no silicon carbide (SiC) remains after the light-shielding film is removed from the phase-shifting film pattern, and changes in the optical properties (phase difference, transmittance, etc.) of the phase-shifting film caused by residual silicon carbide (SiC) are suppressed.

[0101] Furthermore, by forming the fourth layer as a carbon (C)-free layer, even if the phase-shifting film is formed from a material containing transition metals, there is no reaction between the transition metal and carbon (C) at the interface between the light-shielding film and the phase-shifting film containing transition metals (which occurs when the light-shielding film containing chromium (Cr) contains carbon (C)), and no transition metal carbides are formed. Therefore, after removing the light-shielding film from above the phase-shifting film pattern, chromium (Cr) does not remain in the transition metal carbides such as molybdenum carbide (MoC) due to its inclusion, thereby suppressing haze, which would occur if chromium (Cr) remained in the transition metal carbides such as molybdenum carbide (MoC) due to its inclusion.

[0102] The fourth layer contains chromium (Cr), oxygen (O), and nitrogen (N). Specifically, a material composed of chromium (Cr), oxygen (O), and nitrogen (N) is preferably used as the material for forming the fourth layer.

[0103] In the fourth layer, the chromium (Cr) content is preferably 35 atomic% or more, more preferably 37 atomic% or more, and preferably 44 atomic% or less, more preferably 43 atomic% or less. In the fourth layer, the oxygen (O) content is preferably 42 atomic% or more, more preferably 45 atomic% or more, and preferably 54 atomic% or less, more preferably 50 atomic% or less. In the fourth layer, the nitrogen (N) content is preferably 2 atomic% or more, more preferably 8 atomic% or more, and preferably 20 atomic% or less, more preferably 12 atomic% or less.

[0104] The fourth layer preferably has a thickness such that carbon (C) contained in the layers other than the fourth layer does not reach the sidewalls of the phase-shifting film. Furthermore, from the viewpoint of obtaining the required light-blocking properties (optical density (OD)) for the entire light-blocking film, the fourth layer is preferably formed to be relatively thick among the first, second, third, and fourth layers, because the fourth layer has a relatively high optical density (OD) per unit thickness. The thickness of the fourth layer is preferably 18 nm or more, more preferably 20 nm or more, and preferably 36 nm or less, more preferably 34 nm or less.

[0105] To ensure a sufficient etching rate for the light-shielding film during dry etching using an oxygen-containing chlorine (Cl)-based gas, it is preferable that the light-shielding film contains carbon (C), and contains a large amount of carbon (C). The presence of carbon (C) helps impart etching properties similar to chromium carbide (CrN) to chromium (Cr)-containing materials, which have a relatively low density and are easily etched using dry etching with an oxygen-containing chlorine (Cl)-based gas. Therefore, a second layer containing carbon (C) is provided. Furthermore, the presence of oxygen (O) in the light-shielding film helps improve the etching rate during dry etching using an oxygen-containing chlorine (Cl)-based gas. Moreover, when a light-shielding film pattern is formed from the light-shielding film using dry etching with an oxygen-containing chlorine (Cl)-based gas, it is preferable to provide a larger amount of oxygen (O) from the light-shielding film to assist in the processing of forming finely spaced patterns by plasma; therefore, the inclusion of oxygen (O) is effective.

[0106] The second layer contains chromium (Cr), oxygen (O), nitrogen (N), and carbon (C). Specifically, a material composed of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) is preferably used as the material for forming the second layer.

[0107] In the second layer, the chromium (Cr) content is preferably 30 atomic% or more, more preferably 32 atomic% or more, and preferably 45 atomic% or less, more preferably 43 atomic% or less. In the second layer, the oxygen (O) content is preferably 28 atomic% or more, more preferably 30 atomic% or more, and preferably 40 atomic% or less, more preferably 38 atomic% or less. In the second layer, the nitrogen (N) content is preferably 12 atomic% or more, more preferably 14 atomic% or more, and preferably 24 atomic% or less, more preferably 22 atomic% or less. In the second layer, the carbon (C) content is preferably 5 atomic% or more, more preferably 7 atomic% or more, and preferably 15 atomic% or less, more preferably 12 atomic% or less.

[0108] When manufacturing a phase-shifting mask from a phase-shifting mask blank, from the viewpoint of obtaining the light-shielding properties (optical density (OD)) required for the entire light-shielding film, the second layer has a relatively high optical density (OD) per unit thickness. Furthermore, from the viewpoint of shortening the time (clearance time) for etching the entire light-shielding film to thin the resist film, the second layer has a high etching rate. Therefore, it is preferable to form the second layer as relatively thick among the first, second, third, and fourth layers. Additionally, the thinner the second layer, the more effectively the sheet resistance of the third layer (described below) can be reduced, thereby allowing a material with relatively low conductivity (relatively high sheet resistance) to be used as the material for the second layer. The thickness of the second layer is preferably 18 nm or more, more preferably 20 nm or more, and preferably 24 nm or less, more preferably 20 nm or less.

[0109] When a phase-shifting mask is manufactured from a phase-shifting mask blank, a resist film is typically formed in contact with the light-shielding film. If the light-shielding film has a high sheet resistance, when an electron beam is used to draw a pattern in the resist film, the surface layer of the light-shielding film may become charged by the electron beam, causing the electron beam's irradiation position to deviate, and the electron beam may not irradiate the intended location. If the electron beam's irradiation position deviates, a pattern cannot be formed at the intended location, resulting in the inaccurate formation of the circuitry for the device to be manufactured. Therefore, the light-shielding film preferably has a low sheet resistance.

[0110] When the first, second, and fourth layers are formed from materials containing chromium (Cr) and oxygen (O), materials containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), and materials containing chromium (Cr), oxygen (O), and nitrogen (N), respectively, and have a relatively low chromium (Cr) content, their sheet resistance becomes relatively high. Furthermore, when the first, second, and fourth layers have an oxygen-rich composition with a relatively high oxygen (O) content, the first, second, and fourth layers with the oxygen-rich composition have relatively high sheet resistance because chromium oxide (CrO) has a higher sheet resistance than chromium nitride (CrN).

[0111] Therefore, from the viewpoint of reducing the sheet resistance of the entire light-shielding film, the third layer contains chromium (Cr) and nitrogen (N), has a relatively high chromium (Cr) content, and contains no oxygen (O) or has a relatively low oxygen (O) content. Even if the sheet resistance of the first, second, and fourth layers is relatively high, providing the third layer can reduce the sheet resistance of the entire light-shielding film. Although the third layer can be disposed on the fourth layer side (i.e., the first, second, third, and fourth layers can be arranged in this order from the side away from the transparent substrate) or on the first layer side (i.e., the first, third, second, and fourth layers can be arranged in this order from the side away from the transparent substrate) with respect to the second layer, from the perspective of the resolution when forming a resist film on a light-shielding film that is contacted with an aqueous solution containing sulfuric acid to form micropatterns, it is preferable to dispose of the third layer on the fourth layer side with respect to the second layer.

[0112] The third layer contains chromium (Cr) and nitrogen (N). Nitrogen (N) can increase the sheet resistance compared to oxygen (O), but chromium nitride (CrN) has a lower etching rate for dry etching using chlorine (Cl)-based gases containing oxygen (O) compared to chromium oxide (CrO). Therefore, when manufacturing a phase-shifting mask from a phase-shifting mask blank, from the viewpoint of reducing the sheet resistance of the entire light-shielding film, increasing the etching rate, shortening the etching time (removal time) of the entire light-shielding film, and thinning the resist film used, the third layer preferably contains oxygen (O). The third layer may contain a small amount of carbon (C), but is preferably free of carbon (C). Specifically, the material forming the third layer can be a material composed of chromium (Cr) and nitrogen (N), a material composed of chromium (Cr), nitrogen (N) and carbon (C), a material composed of chromium (Cr), oxygen (O) and nitrogen (N), or a material composed of chromium (Cr), oxygen (O), nitrogen (N) and carbon (C), and preferably a material composed of chromium (Cr), oxygen (O) and nitrogen (N).

[0113] In the third layer, the chromium (Cr) content is preferably 50 atomic% or more, more preferably 52 atomic% or more, and preferably 60 atomic% or less, more preferably 58 atomic% or less. If the third layer contains oxygen (O), the oxygen (O) content is greater than 0 atomic%, preferably 6 atomic% or more, more preferably 10 atomic% or more, and preferably 30 atomic% or less, more preferably 28 atomic% or less. In the third layer, the nitrogen (N) content is preferably 20 atomic% or more, more preferably 22 atomic% or more, and preferably 40 atomic% or less, more preferably 38 atomic% or less. If the third layer contains carbon (C), the carbon (C) content is preferably less than 5 atomic%, more preferably 3 atomic% or less, and even more preferably 2 atomic% or less.

[0114] From the viewpoint of shortening the etching time (removal time) of the entire light-shielding film, the third layer is preferably formed to be relatively thin among the first, second, third, and fourth layers. However, from the viewpoint of reducing the sheet resistance of the entire light-shielding film, the third layer needs to have a certain thickness. The thickness of the third layer is preferably 1 nm or more, more preferably 2 nm or more, and preferably 6 nm or less, more preferably 4 nm or less.

[0115] In the light-shielding film, the total sheet resistance of all layers except the fourth layer in the stacked structure (three layers in the case of the stacked structure including the first, second, third and fourth layers: the first layer, the second layer and the third layer), preferably all layers (four layers in the case of the stacked structure including the first, second, third and fourth layers: the first layer, the second layer, the third layer and the fourth layer) is preferably 350 kΩ / □ or less, more preferably 300 kΩ / □ or less, and even more preferably 250 kΩ / □ or less.

[0116] Preferably, a light-shielding film, particularly a light-shielding film pattern, is used as a hard mask for etching the phase-shifting film. Then, a portion of the light-shielding film pattern is left on the phase-shifting film to form a phase-shifting mask. Specifically, the light-shielding film pattern is left to contact the phase-shifting film outside the area (effective area) where the circuit pattern forming the phase-shifting film pattern is located, so as to form a phase-shifting mask as a light-shielding portion at the outer peripheral portion of the phase-shifting mask.

[0117] When the light-shielding film forms a light-shielding portion (light-shielding film pattern) at the outer peripheral edge of the phase-shift mask, the total optical density (OD) of the phase-shift film and the light-shielding film relative to the exposure light (specifically, light with a wavelength of 200 nm or less, such as ArF excimer laser (wavelength of 193 nm)) is preferably 2 or more, more preferably 2.5 or more, and even more preferably 3 or more. For example, if the phase-shift film has a transmittance of 6% or more to 30% or less relative to the exposure light (optical density (OD) of 0.53 or more to 1.22 or less), in order to make the total optical density (OD) of the phase-shift film and the light-shielding film 3 or more, the light-shielding film needs to have an optical density (OD) of 1.78 or more relative to the exposure light. Note that the upper limit of the optical density (OD) of the light-shielding film relative to the exposure light is generally 3.2 or less.

[0118] The thickness of the light-shielding film (the total thickness of the light-shielding film) is preferably 38 nm or more, more preferably 44 nm or more, and preferably 70 nm or less, more preferably 65 nm or less, and even more preferably 62 nm or less. In particular, when the light-shielding portion (light-shielding film pattern) is formed in the light-shielding film at the outer peripheral edge of the phase-shifting mask, the thickness of the light-shielding film (the total thickness of the light-shielding film) is preferably 48 nm or more, and preferably 54 nm or less.

[0119] The phase-shifting mask blank of the present invention may further include a resist film in contact with the side of the light-shielding film away from the transparent substrate. The resist film may be an electron beam resist drawn with an electron beam or a photoresist drawn with light, and in particular, a chemically amplified resist is preferred. The chemically amplified resist may be positive or negative, and may, for example, contain a base resin such as a hydroxystyrene resin or a (meth)acrylate resin, and an acid generator, and, as needed, a crosslinking agent, a quencher, a surfactant, etc. From the viewpoint of preventing the resist pattern from collapsing during development or during rinsing after development when forming fine patterns, the thickness of the resist film is preferably 200 nm or less, more preferably 150 nm or less. If the resist film is too thin, it may not be possible to form a stable thickness. Therefore, the thickness of the resist film is preferably 40 nm or more, more preferably 50 nm or more.

[0120] There are no particular restrictions on the formation of the phase-shifting film and the light-shielding film (the layers constituting the light-shielding film), but sputtering is preferred because it offers good controllability and facilitates the formation of films with predetermined properties. The sputtering method is not particularly limited; DC sputtering, RF sputtering, etc., can be used.

[0121] When forming a phase-shifted film from a silicon (Si)-containing and carbon (C)-free material, a silicon (Si) target can be used as the sputtering target, and if desired, a transition metal target can be used, preferably a transition metal (Me) other than chromium (Cr), or a target containing both silicon (Si) and a transition metal, preferably a transition metal (Me) other than chromium (Cr). Sputtering can be co-sputtering using multiple types of targets. In this case, a silicon (Si) target and a transition metal (preferably a transition metal (Me) other than chromium (Cr)) target can be used, multiple targets containing both silicon (Si) and a transition metal (preferably a transition metal (Me) other than chromium (Cr)) with different compositions (some or all of the constituent elements are different, or the constituent elements are the same but their concentrations are different) can be used for co-sputtering, or a silicon (Si) target or a transition metal (preferably a transition metal (Me) other than chromium (Cr)) target and a target containing both silicon (Si) and a transition metal (preferably a transition metal (Me) other than chromium (Cr)) can be used for co-sputtering.

[0122] On the other hand, when the light-shielding film is formed of a material containing chromium (Cr), oxygen (O), nitrogen (N) and carbon (C) (in the case of forming a layer constituting the light-shielding film), a chromium (Cr) target can be used as a sputtering target.

[0123] The power input to the sputtering target can be appropriately set according to the size of the sputtering target, cooling efficiency, and controllability of film formation, and the power per unit area of ​​the sputtering surface of the sputtering target can typically be from 0.1 to 10 W / cm². 2 .

[0124] When the phase-shifting film is formed from a material composed solely of silicon (Si) or a material composed solely of silicon (Si) and transition metals, only inert gases such as helium (He), neon (Ne), or argon (Ar) are used as sputtering gases. On the other hand, when the phase-shifting film is formed from a material containing one or both of oxygen (O) and nitrogen (N), reactive sputtering is preferred. In this case, a reactive gas and an inert gas such as helium (He), neon (Ne), or argon (Ar) are used as sputtering gases. For example, when the phase-shifting film contains oxygen (O), oxygen gas (O2) can be used as the reactive gas, and when the phase-shifting film contains nitrogen (N), nitrogen gas (N2) can be used as the reactive gas. In addition, when the phase-shifting membrane contains both oxygen (O) and nitrogen (N), oxygen (O2 gas) and nitrogen (N2 gas) can be used simultaneously as reactive gases, or nitrogen oxide gases such as nitric oxide (NO gas), nitrogen dioxide (NO2 gas) or nitrous oxide (N2O gas) can be used as reactive gases.

[0125] On the other hand, when the light-shielding film is formed of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) (in the case of forming the layers constituting the light-shielding film), reactive sputtering is preferred. In this case, a reactive gas and an inert gas such as helium (He), neon (Ne), or argon (Ar) are used as the sputtering gas. For example, if the layers constituting the light-shielding film contain oxygen (O), oxygen gas (O2) can be used as the reactive gas, and if the layers constituting the light-shielding film contain nitrogen (N), nitrogen gas (N2) can be used as the reactive gas. If the layers constituting the light-shielding film contain both oxygen (O) and nitrogen (N), both oxygen gas (O2) and nitrogen gas (N2) can be used as the reactive gas, or nitrogen oxide gases such as nitric oxide gas (NO), nitrogen dioxide gas (NO2), and nitrous oxide gas (N2O) can be used as the reactive gas. When the layers constituting the light-shielding film contain carbon (C), carbon oxide gases such as carbon monoxide (CO gas) or carbon dioxide (CO2 gas) can be used as reactive gases.

[0126] The pressure during film formation can be appropriately set considering factors such as membrane stress, chemical resistance, and washability. Generally, a pressure of 0.01 Pa or higher is preferred, more preferably 0.03 Pa or higher, and more preferably 1 Pa or lower, more preferably 0.3 Pa or lower, to improve chemical resistance. The flow rates of each gas can be appropriately set to obtain the desired composition, typically from 0.1 to 100 sccm.

[0127] During the fabrication of a phase-shifting mask blank, the transparent substrate or the transparent substrate and the film formed on the transparent substrate can be subjected to heat treatment. Infrared heating, resistance heating, etc., can be used as heat treatment methods, and the processing conditions are not particularly limited. For example, the heat treatment can be carried out in an oxygen (O) gas atmosphere. The concentration of the oxygen (O) gas is not particularly limited; for example, in the case of oxygen (O2 gas), it can be 1 to 100% by volume. The heat treatment temperature is preferably 200°C or higher, more preferably 400°C or higher. Furthermore, during the fabrication of the phase-shifting mask blank, the film formed on the transparent substrate, particularly the light-shielding film, can be subjected to ozone (O3) treatment, plasma treatment, etc., and the processing conditions are not particularly limited. To increase the oxygen (O) concentration in the surface portion of the film, any treatment can be performed; in this case, the processing conditions can be appropriately adjusted to obtain a predetermined oxygen (O) concentration. In the case of film formation by sputtering, the concentration of oxygen (O) in the film surface portion can be increased by adjusting the ratio between the inert gas and the oxygen (O) gas (oxidizing gas) in the sputtering gas, such as oxygen (O2 gas), carbon monoxide gas (CO gas), or carbon dioxide gas (CO2 gas).

[0128] During the fabrication of the phase-shifting mask preform, a cleaning process can be performed to remove particles present on the surface of the transparent substrate or on the film formed on the transparent substrate. Cleaning can be performed using one or both of ultrapure water and functional water, wherein the functional water is ultrapure water containing ozone gas (O3 gas), hydrogen gas (H2 gas), etc. Furthermore, after cleaning with ultrapure water containing surfactants, further cleaning can be performed using one or both of ultrapure water and functional water. Cleaning can be performed as needed during ultrasonic irradiation or in combination with ultraviolet lamp irradiation.

[0129] When a resist film is formed on the photomask blank of the present invention, the method of forming the resist film is not particularly limited, and known methods such as spin coating can be applied.

[0130] The phase-shifting mask blank of the present invention allows for the fabrication of phase-shifting masks using conventional methods without the need for special developing processes or special dry etching. Furthermore, because the etching rate is high when dry etching the light-shielding film using an oxygen-containing (O) chlorine (Cl)-based gas, and the time required to etch the entire light-shielding film (removal time) is short, the resist film is formed thin. This allows for the fabrication of phase-shifting masks using conventional methods and prevents the fine line patterns from collapsing during resist film development due to developer collisions, resulting in a good resolution limit when forming auxiliary line patterns that enhance the resolution of the main pattern of the phase-shifting mask.

[0131] The phase-shift mask blank of the present invention can be used to manufacture a phase-shift mask having a circuit pattern with a phase-shift film and having a light-shielding portion (light-shielding film pattern) at the outer peripheral edge, which is a region where no circuit pattern of the phase-shift mask is formed. Specifically, a phase-shift mask having a circuit pattern with a phase-shift film in the effective area of ​​the phase-shift mask and having a light-shielding portion (light-shielding film pattern) at the outer peripheral edge of the phase-shift mask can be manufactured by a method including the steps (A) to (I).

[0132] First, a first resist film is formed on the light-shielding film as needed (step (A)). In cases where no resist film is formed on the phase-shifting mask blank, this step involves forming a resist film on the light-shielding film in contact with it. This step is not necessary when using a phase-shifting mask blank on which a resist film has been formed. The first resist film can be a resist film similar to that described in the phase-shifting mask blank, and it can also have a similar thickness. There are no particular limitations on the method of forming the resist film, and known methods such as spin coating can be applied.

[0133] Next, a first resist pattern is formed by patterning the first resist film (step (B)). The first resist pattern can be formed by drawing a pattern on the resist film using light or an electron beam and developing the pattern using known methods.

[0134] Next, using the first resist pattern as an etching mask, the light-shielding film is patterned by dry etching using an oxygen (O)-containing chlorine (Cl)-based gas to form the light-shielding film pattern (step (C)).

[0135] Next, the phase shift film pattern is formed by using a light-shielding film pattern as an etching mask and using fluorine (F)-based gas to pattern the phase shift film through dry etching (step (D)).

[0136] Next, the first resist pattern is removed (step (E)). The first resist pattern can be removed by washing with a sulfuric acid / hydrogen peroxide solution (a mixture of sulfuric acid and hydrogen peroxide).

[0137] Next, a second resist film is formed on the light-shielding film pattern (step (F)). In this case, the second resist film is formed on the light-shielding film pattern that is in contact with it, and also on and in contact with the portion exposed by removing the phase-shifting film (the transparent substrate or another film formed between the transparent substrate and the phase-shifting film as needed). As the second resist film, a resist film similar to the resist film included in the phase-shifting mask blank described above can be used, and in particular, a resist film for laser drawing is suitable. The second resist film preferably has a thickness of 250 nm or more and 500 nm or less.

[0138] Next, a second resist pattern is formed on the outer peripheral edge portion outside the region where the circuit pattern of the phase-shifting film is formed (step (G)). The second resist pattern can be formed by drawing a pattern on the resist film using light or an electron beam and developing the pattern using known methods.

[0139] Next, using the second resist pattern as an etching mask, the light-shielding film pattern in the area (effective area) where the circuit pattern with the phase-shifting film is formed is removed by dry etching using an oxygen (O)-containing chlorine (Cl)-based gas (step (H)).

[0140] Next, the second resist pattern is removed (step (I)). The second resist pattern can be removed by washing with a sulfuric acid / hydrogen peroxide solution (a mixture of sulfuric acid and hydrogen peroxide).

[0141] The phase shifting film pattern of the phase shifting mask preferably has optical properties (phase difference, transmittance, etc.) that remain almost unchanged even when in contact with an aqueous sulfuric acid solution used to remove the resist film and clean the phase shifting mask. This resist film is used to form a light-shielding portion (light-shielding film pattern) on the outer peripheral edge of the phase shifting mask during the manufacturing process of the phase shifting mask from the phase shifting mask blank.

[0142] Therefore, when the phase-shifting film is contacted with an aqueous solution containing sulfuric acid to remove the resist film pattern as described in step (I) above, the change in the phase difference of the phase-shifting film (the change in the value set for the phase difference of the phase-shifting film in the phase-shifting mask blank state) is preferably 0.2 degrees or less, more preferably 0.1 degrees or less, and even more preferably 0.03 degrees or less, and the change in the transmittance of the phase-shifting film (the change in the value set for the transmittance of the phase-shifting film in the phase-shifting mask blank state) is preferably 0.05% (percentage point) or less, more preferably 0.01% (percentage point) or less.

[0143] Furthermore, when the phase-shifting film is contacted with an aqueous solution containing sulfuric acid to clean the phase-shifting mask, specifically, when the phase-shifting mask is cleaned (at 100°C and for 30 minutes) with a sulfuric acid / hydrogen peroxide solution (a mixed solution of sulfuric acid and hydrogen peroxide = 3:1 (volume ratio)), the change in phase difference of the phase-shifting film is preferably 0.3 degrees or less, more preferably 0.2 degrees or less, and even more preferably 0.14 degrees or less, and the change in transmittance of the phase-shifting film is preferably 0.10% (percentage point) or less, more preferably 0.05% (percentage point) or less, and even more preferably 0.04% (percentage point) or less. Note that the above-mentioned changes in phase difference and transmittance refer to the difference in phase difference and the difference in transmittance.

[0144] In photolithography, where a pattern is transferred onto a photoresist film formed on a wafer (substrate to be processed) using exposure light with a wavelength of less than 200 nm, such as an ArF excimer laser (wavelength 193 nm), the phase-shifting mask of the present invention is particularly effective in forming a pattern with a half-pitch of less than 50 nm, preferably less than 30 nm, more preferably less than 20 nm, and even more preferably less than 10 nm on the wafer (substrate to be processed).

[0145] Using a phase-shift mask manufactured from the phase-shift mask blank of the present invention, a phase-shift mask pattern (photomask pattern) can be irradiated with exposure light, thereby transferring the photomask pattern onto a photoresist film formed on a wafer (substrate to be processed), which is the object to be exposed by the photomask pattern. Irradiation with exposure light can be used by exposure under dry conditions or by immersion exposure, and it is particularly suitable when exposing the photomask pattern to a wafer (substrate to be processed) of 300 mm or more by immersion exposure.

[0146] Exposure light from a wafer exposure apparatus is applied to a phase-shift mask, and the exposure light is blocked within a light-shielding film pattern. In the circuit pattern (halftone phase-shift film pattern), a portion of the exposure light in the line pattern is blocked, while the blocked light in the spacing pattern passes through a transparent substrate and illuminates the photoresist film on the wafer (substrate to be processed). Preferably, the phase-shift mask can be used for extended periods without haze, even when the accumulated exposure light reaching the phase-shift film has reached a certain level. From this perspective, it is preferable that the mask be used until the accumulated exposure light reaches 40 kJ / cm². 2 The phase-shifting mask does not produce haze, and more preferably, the cumulative exposure light intensity reaches 50 kJ / cm². 2 The phase-shift mask then produces a haze. Preferably, the haze is produced only when the exposure light reaches the above-mentioned range. The haze is one or both of the haze caused by ammonium sulfate ((NH4)2SO4) and haze caused by chromium oxide (CrO).

[0147] Example

[0148] The present invention will now be described in detail through examples and comparative examples, but the present invention is not limited to the following examples.

[0149] In each embodiment and comparative example, a phase shift mask blank (halftone phase shift mask blank) is manufactured on a transparent substrate made of synthetic quartz glass with a size of 152 square millimeters and a thickness of about 6 mm by stacking a phase shift film (halftone phase shift film) formed of a silicon (Si) material and a light-shielding film formed of a material containing chromium (Cr), oxygen (O), nitrogen (N) and carbon (C).

[0150] Examples 1 to 10

[0151] First, a monolayer phase-shifting film (65 nm thick) of silicon nitride (SiN) was formed on a transparent substrate by sputtering in an argon and nitrogen atmosphere with a phase difference of 177 degrees relative to an ArF excimer laser (wavelength 193 nm) and a transmittance of 6% (optical density (OD) of 1.22) using argon (Ar) and nitrogen (N2) as sputtering gases. Table 1 shows the composition of the phase-shifting film and the zeta potential at pH 3, 4, 5, and 6. The composition of the phase-shifting film was measured by X-ray photoelectron spectroscopy (also applicable to the following examples). The zeta potential was measured using an electrophoretic light scattering spectrophotometer (also applicable to the following examples).

[0152] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a second layer, a third layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxynitride (CrON), the second layer is formed of chromium carbonitride (CrONC), the third layer is formed of chromium oxynitride (CrON), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the third layer, the second layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1. The composition of each layer of the light-shielding film was measured by X-ray photoelectron spectroscopy (also applicable to the following embodiments). In addition, the sheet resistance was measured by the four-point probe method (also applicable to the following embodiments).

[0153] Example 11

[0154] First, by adjusting the applied power to the targets (using silicon (Si) and molybdenum (Mo) targets), and sputtering in a gas atmosphere containing argon, oxygen, and nitrogen, using argon (Ar), oxygen (O2), and nitrogen (N2) as sputtering gases, a monolayer phase-shifting film (69 nm thick) of molybdenum oxynitride (MoSiON) was formed on a transparent substrate with a phase difference of 177 degrees relative to the ArF excimer laser (wavelength 193 nm) and a transmittance of 6% (optical density (OD) of 1.22). Table 1 shows the composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6.

[0155] Next, a phase-shift mask blank was obtained by forming a light-shielding film similar to that in Example 1 on the phase-shift film using a method similar to that in Example 1. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0156] Example 12

[0157] First, a phase-shifting film, similar to that of Example 11, was formed on a transparent substrate using a method similar to that of Example 11. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 1.

[0158] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a second layer, a third layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxide (CrO), the second layer is formed of chromium carbonitride (CrONC), the third layer is formed of chromium oxynitride (CrON), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the third layer, the second layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0159] Example 13

[0160] First, a phase-shifting film, similar to that of Example 11, was formed on a transparent substrate using a method similar to that of Example 11. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 1.

[0161] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a second layer, a third layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxynitride (CrON), the second layer is formed of chromium carbonitride (CrONC), the third layer is formed of chromium nitride (CrN), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the third layer, the second layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0162] Example 14

[0163] First, a phase-shifting film, similar to that of Example 11, was formed on a transparent substrate using a method similar to that of Example 11. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 1.

[0164] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a second layer, a third layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium carbonitride (CrONC), the second layer is formed of chromium carbonitride (CrONC), the third layer is formed of chromium oxynitride (CrON), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the third layer, the second layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0165] Example 15

[0166] First, a phase-shifting film, similar to that of Example 11, was formed on a transparent substrate using a method similar to that of Example 11. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 1.

[0167] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a second layer, a third layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxynitride (CrON), the second layer is formed of chromium carbonitride (CrONC), the third layer is formed of chromium carbonitride (CrONC), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the third layer, the second layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0168] Example 16

[0169] First, a phase-shifting film, similar to that of Example 1, was formed on a transparent substrate using a method similar to that of Example 1. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 1.

[0170] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a third layer, a second layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxynitride (CrON), the third layer is formed of chromium oxynitride (CrON), the second layer is formed of chromium carbonitride (CrONC), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the second layer, the third layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0171] Example 17

[0172] First, a phase-shifting film, similar to that of Example 11, was formed on a transparent substrate using a method similar to that of Example 11. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 1.

[0173] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a third layer, a second layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxynitride (CrON), the third layer is formed of chromium oxynitride (CrON), the second layer is formed of chromium carbonitride (CrONC), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the second layer, the third layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0174] Comparative Example 1

[0175] First, by adjusting the applied power to the targets (using silicon (Si) and molybdenum (Mo) targets), sputtering was performed in a gas atmosphere containing argon, oxygen, and nitrogen using argon (Ar), oxygen (O2), and nitrogen (N2) as sputtering gases to form a 75 nm thick monolayer phase-shifting film of silicon-oxygen-molybdenum (MoSiON) on a transparent substrate. The phase shifting film had a phase difference of 177 degrees relative to the ArF excimer laser (wavelength 193 nm) and a transmittance of 6% (optical density (OD) of 1.22). Table 2 shows the composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6.

[0176] Next, a phase-shifting mask blank was obtained by forming a single-layer chromium carbonitride oxide (CrONC) light-shielding film on the phase-shifting film as follows: adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar gas), oxygen (O2 gas), nitrogen (N2 gas), and carbon dioxide (CO2 gas) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering was performed in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0177] Comparative Example 2

[0178] First, a phase-shifting film similar to that of Comparative Example 1 was formed on a transparent substrate using a method similar to that of Comparative Example 1. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 2.

[0179] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a second layer, a third layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxynitride (CrON), the second layer is formed of chromium carbonitride (CrONC), the third layer is formed of chromium oxynitride (CrON), and the fourth layer is formed of chromium carbonitride (CrONC). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the third layer, the second layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0180] Comparative Example 3

[0181] First, a phase-shifting film, similar to that of Example 1, was formed on a transparent substrate using a method similar to that of Example 1. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 2.

[0182] Next, a light-shielding film similar to that of Comparative Example 1 was formed on the phase-shifting film using a method similar to that of Comparative Example 1 to obtain a phase-shifting mask blank. The composition and thickness of each layer of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0183] Comparative Example 4

[0184] First, a phase-shifting film similar to that of Comparative Example 1 was formed on a transparent substrate using a method similar to that of Comparative Example 1. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 2.

[0185] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. This light-shielding film consists of two layers: an upper layer and a lower layer, arranged sequentially from the side away from the transparent substrate. The upper layer is formed of chromium carbonitride (CrONC), and the lower layer is formed of chromium nitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the lower and upper layers (in that order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) relative to the ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0186] Comparative Example 5

[0187] First, a phase-shifting film similar to that of Comparative Example 1 was formed on a transparent substrate using a method similar to that of Comparative Example 1. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 2.

[0188] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. This light-shielding film consists of three layers: an upper layer, a middle layer, and a lower layer, arranged sequentially from the side away from the transparent substrate. The upper layer is formed of chromium oxynitride (CrON), the middle layer is formed of chromium carbonitride (CrONC), and the lower layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the lower, middle, and upper layers (in that order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0189] Comparative Example 6

[0190] First, a phase-shifting film, similar to that of Example 1, was formed on a transparent substrate using a method similar to that of Example 1. The composition of the phase-shifting film and its zeta potential at pH 3, 4, 5, and 6 are shown in Table 2.

[0191] Next, a phase-shift mask blank is obtained by forming a light-shielding film on the phase-shift film. The light-shielding film consists of a first layer, a second layer, a third layer, and a fourth layer in sequence from the side away from the transparent substrate. The first layer is formed of chromium oxynitride (CrON), the second layer is formed of chromium carbonitride (CrONC), the third layer is formed of chromium carbonitride (CrONC), and the fourth layer is formed of chromium oxynitride (CrON). The light-shielding film is formed by adjusting the power applied to the target (using a chromium (Cr) target as the target), using argon (Ar), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2) as sputtering gases, adjusting the ratio between the sputtering gases, and sputtering the fourth layer, the third layer, the second layer, and the first layer (in this order) in a gas atmosphere containing argon, oxygen, nitrogen, and carbon dioxide. The composition and thickness of each layer in the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) of the light-shielding film relative to the ArF excimer laser (wavelength 193nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0192] Table 1

[0193]

[0194] Table 2

[0195]

[0196] Next, using the phase-shift mask blanks obtained in each embodiment and comparative example, dry etching was performed using an oxygen-containing (O) chlorine (Cl)-based gas under the following condition 1, and the clearance time (the time from dry etching until the light-shielding film disappears and the endpoint is detected) was measured. The clearance time and the etching rate obtained from the thickness of the light-shielding film and the clearance time are shown in Table 3.

[0197] <Condition 1: Dry etching using an oxygen-containing (O) chlorine (Cl)-based gas>

[0198] Apparatus: Inductively Coupled Plasma (ICP) type

[0199] Gas: Cl2 gas (150 sccm) + O2 gas (50 sccm)

[0200] Atmospheric pressure: 3.0 mTorr (0.40 Pa)

[0201] ICP power: 350W

[0202] Table 3

[0203]

[0204] In each embodiment of the light-shielding film, the fourth layer is carbon-free (C), but the second layer contains carbon (C), and the oxygen (O) content of the first and fourth layers is relatively high. Specifically, in each of Examples 7 and 10, the chromium (Cr) content of the second layer is relatively low, and the oxygen (O) content of the second layer is relatively high. Therefore, as shown in Table 3, even though the light-shielding film includes a third layer with a relatively high nitrogen (N) content, the time for etching the entire light-shielding film (removal time) is shorter than that in Comparative Example 1. Furthermore, in each embodiment of the light-shielding film, the required light-shielding performance (optical density (OD)) for the entire light-shielding film is ensured.

[0205] Next, a phase-shift mask is manufactured using another phase-shift mask blank obtained in each embodiment and comparative example.

[0206] First, a positive chemical amplification electron beam resist is spin-coated onto a light-shielding film to form a first resist film with a thickness of 120 nm (step (A)).

[0207] Next, an electron beam lithography apparatus was used at 35 μC / cm. 2 A total of 100 million lines and spacing patterns with a long side dimension of 100,000 nm, a short side dimension of 200 nm, and a short side spacing dimension of 200 nm were drawn using a specific dosage. Additionally, 10 mm × 10 mm spacing patterns were drawn to measure phase difference and transmittance. Next, a heat treatment was performed at 110°C for 14 minutes (post-exposure baking (PEB)). Following this, a paddle development process was performed for 80 seconds to form the first resist pattern (step B).

[0208] Next, using the first resist pattern as an etching mask, the light-shielding film is patterned by dry etching with an oxygen (O)-containing chlorine (Cl)-based gas under the following conditions 2 to form a light-shielding film pattern (step (C)).

[0209] <Condition 2: Dry etching using an oxygen-containing (O) chlorine (Cl)-based gas>

[0210] Apparatus: Inductively Coupled Plasma (ICP) type

[0211] Gas: Cl2 gas (150 sccm) + O2 gas (50 sccm)

[0212] Atmospheric pressure: 3.0 mTorr (0.40 Pa)

[0213] ICP power: 350W

[0214] Etching time: 100% (Etching time: 200% of the clearing time)

[0215] Next, using the light-shielding film pattern as an etching mask, the phase shift film is patterned by dry etching with fluorine (F)-based gas under the following conditions 3 to form a phase shift film pattern (step (D)).

[0216] <Condition 3: Dry etching using fluorine (F)-based gases>

[0217] Apparatus: Inductively Coupled Plasma (ICP) type

[0218] Gas: SF6 gas + He gas

[0219] Atmospheric pressure: 4.0 mTorr (0.53 Pa)

[0220] ICP power: 400W

[0221] Next, the first resist pattern is removed by cleaning with a sulfuric acid / hydrogen peroxide solution (a mixture of sulfuric acid and hydrogen peroxide in a volume ratio of 3:1) (cleaning at 100°C for 6 minutes) (step (E)).

[0222] Next, a resist for laser drawing is spin-coated onto the transparent substrate exposed by removing the light-shielding film pattern and the phase-shifting film to form a second resist film with a thickness of 465 nm (thickness on the transparent substrate) (step (F)).

[0223] Next, an effective area of ​​the circuit pattern including the phase-shifting film is drawn using a laser drawing device, such that the second resist film is retained in the portion located at the outer peripheral edge of the transparent substrate. Then, a heat treatment (post-exposure baking (PEB)) is performed at 110°C for 20 minutes using a heat treatment device. Next, a development process of 200 seconds is performed by jet developing to form the second resist pattern on the outer peripheral edge portion outside the area where the circuit pattern with the phase-shifting film is formed (step (G)).

[0224] Next, using the second resist pattern as an etching mask, dry etching is performed under the above conditions 2 using an oxygen (O)-containing chlorine (Cl)-based gas to remove the light-shielding film pattern in the area where the circuit pattern with the phase-shifting film is formed (step (H)).

[0225] Next, the second resist pattern is removed by cleaning with a sulfuric acid / hydrogen peroxide solution (a mixture of sulfuric acid and hydrogen peroxide in a volume ratio of 3:1) (for 6 minutes at 100°C) (step (I)) to obtain a phase-shifting mask.

[0226] Next, the phase difference and transmittance between the 10 mm × 10 mm spaced pattern formed on the obtained phase-shift mask and the surrounding phase-shift film pattern were measured using a phase difference and transmittance measurement device, and the differences between them and the set values ​​of phase difference and transmittance for the phase-shift film were obtained (the difference between the set value and the measured value of phase difference and transmittance (the difference before and after manufacturing)). The results are shown in Table 4.

[0227] Next, the phase-shift mask was cleaned five times with a sulfuric acid / hydrogen peroxide solution (a mixture of sulfuric acid and hydrogen peroxide in a 3:1 volume ratio) (for 6 minutes at 100°C). Then, the phase difference and transmittance between the 10 mm × 10 mm spacer pattern formed on the obtained phase-shift mask and the surrounding phase-shift film pattern were measured using a phase difference and transmittance measurement device, and the differences between these values ​​and those before cleaning the phase-shift film pattern were obtained (the difference in phase difference and transmittance before and after cleaning). The results are shown in Table 4.

[0228] Table 4

[0229]

[0230]

[0231] Compared with the phase shift film pattern of the carbon (C) layer in the contact light-shielding film, it was confirmed that the phase shift film pattern of the carbon (C) non-carbon (C) layer in the contact light-shielding film suppressed the changes in phase difference and transmittance of the phase shift film (phase shift film pattern) in contact with sulfuric acid / hydrogen peroxide solution.

[0232] Next, a phase-shifting mask, on which the changes in phase difference and transmittance have been measured, is placed into an exposure apparatus. A line and spacing pattern with a long side dimension of 100,000 nm, a short side dimension of 200 nm, and a short side spacing dimension of 200 nm is formed on this phase-shifting mask. The mask is then irradiated with an ArF excimer laser (wavelength 193 nm) under the following condition 4. Then, the cumulative dose for each irradiation reaches 10 kJ / cm². 2 20kJ / cm 2 30kJ / cm 2 40kJ / cm 2 or 50kJ / cm 2 At that time, the phase-shift mask was removed from the exposure equipment until haze was detected, and the mask pattern was used to check for defects in the equipment evaluation lines and spacing patterns. The composition of the defects was analyzed using TEM / EDX to identify haze of ammonium sulfate ((NH4)2SO4) and chromium oxide (CrO). The results are shown in Table 5.

[0233] <Condition 4: Irradiation conditions of ArF excimer laser (wavelength 193nm)>

[0234] Laser intensity: 2.5 mJ / pulse / cm 2

[0235] Laser frequency: 1600Hz

[0236] Laser irradiation area: 5mm × 5mm

[0237] Temperature in the exposure chamber (atmosphere with phase-shifting masks installed): 23℃

[0238] Humidity in the exposure chamber (atmosphere with a phase-shifting mask installed): 43%

[0239] Table 5

[0240]

[0241] Compared to phase-shift film patterns with a carbon (C) layer in contact with the light-shielding film, it was confirmed that the occurrence of chromium oxide haze was suppressed in phase-shift film patterns in contact with a carbon-free (C) layer of the light-shielding film, and the occurrence of chromium oxide haze was also suppressed even when the phase-shift film pattern contained molybdenum (Mo). Furthermore, it was confirmed that chromium oxide haze appeared in molybdenum (Mo)-containing phase-shift film patterns in contact with a carbon (C) layer of the light-shielding film. Moreover, compared to phase-shift films (phase-shift film patterns) where the ze potential did not meet a predetermined range, it was confirmed that the occurrence of ammonium sulfate haze ((NH4)2SO4) was suppressed in phase-shift films (phase-shift film patterns) where the ze potential met a predetermined range (a ze potential of -15mV to +15mV at pH 3 to 4 and a ze potential of -60mV to +10mV at pH 5 to 6).

Claims

1. A phase shift mask blank, comprising: a transparent substrate; a phase shift film provided on the transparent substrate and formed of a material containing silicon (Si) and not containing carbon (C); and a light shielding film provided on a side of the phase shift film distal from the transparent substrate and formed of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), wherein the light shielding film has a layered structure including, in order from the side distal from the transparent substrate, four layers of a first layer, a second layer, a third layer, and a fourth layer, or four layers of a first layer, a third layer, a second layer, and a fourth layer, in the layered structure, the first layer is a layer most distal from the transparent substrate, and the fourth layer is a layer in contact with the phase shift film, the first layer contains chromium (Cr) and oxygen (O), the chromium (Cr) content is 28 atomic% or more and 40 atomic% or less, the oxygen (O) content is 47 atomic% or more and 60 atomic% or less, and the first layer has a thickness of 1 nm or more and 4 nm or less, the second layer contains chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), the chromium (Cr) content is 30 atomic% or more and 45 atomic% or less, the oxygen (O) content is 28 atomic% or more and 40 atomic% or less, the nitrogen (N) content is 12 atomic% or more and 24 atomic% or less, and the carbon (C) content is 5 atomic% or more and 15 atomic% or less, and the second layer has a thickness of 18 nm or more and 24 nm or less, the third layer contains chromium (Cr) and nitrogen (N), the chromium (Cr) content is 50 atomic% or more and 60 atomic% or less, the nitrogen (N) content is 20 atomic% or more and 40 atomic% or less, and the third layer has a thickness of 1 nm or more and 6 nm or less, and the fourth layer contains chromium (Cr), oxygen (O), and nitrogen (N), and does not contain carbon (C), the chromium (Cr) content is 35 atomic% or more and 44 atomic% or less, the oxygen (O) content is 42 atomic% or more and 54 atomic% or less, and the nitrogen (N) content is 2 atomic% or more and 20 atomic% or less, and the fourth layer has a thickness of 18 nm or more and 36 nm or less.

2. The phase shift mask blank according to claim 1, wherein the phase shift film has a zeta potential of -15 mV or more and +15 mV or less at a pH of 3 or more and 4 or less, and a zeta potential of -60 mV or more and +10 mV or less at a pH of 5 or more and 6 or less.

3. The phase shift mask blank according to claim 1, wherein the first layer contains nitrogen (N), the nitrogen (N) content is 5 atomic% or more and 25 atomic% or less, and the third layer contains oxygen (O), the oxygen (O) content is 6 atomic% or more and 30 atomic% or less.

4. The phase shift mask blank according to claim 1, wherein the material forming the phase shift film contains nitrogen (N).

5. The phase shift mask blank according to claim 1, wherein the material forming the phase shift film does not contain a transition metal. ​ 6. The phase shift mask blank according to claim 1, wherein the total sheet resistance of the first layer, the second layer, the third layer and the fourth layer of the light shielding film is 350 kΩ / D or less.

7. The phase shift mask blank according to claim 1, wherein the phase shift film has a phase difference of 175 degrees or more to 185 degrees or less and a transmittance of 6% or more to 30% or less with respect to ArF excimer laser light (wavelength 193 nm) exposure light, and the phase shift film has a thickness of 60 nm or more to 85 nm or less.

8. The phase shift mask blank according to claim 1, wherein the total optical density (OD) of the phase shift film and the light shielding film with respect to ArF excimer laser light (wavelength 193 nm) exposure light is 3 or more.

9. The phase shift mask blank according to claim 8, wherein the light shielding film has a thickness of 48 nm or more and 54 nm or less.

10. A method for manufacturing a phase shift mask having a circuit pattern of a phase shift film from the phase shift mask blank according to claim 1, the method comprising: (A) forming a first resist film on the light shielding film; (B) forming a first resist pattern by patterning the first resist film; (C) forming a light shielding film pattern by patterning the light shielding film by dry etching using a chlorine (Cl) -based gas containing oxygen (O) using the first resist pattern as an etching mask; (D) forming a phase shift film pattern by patterning the phase shift film by dry etching using a fluorine (F) -based gas using the light shielding film pattern as an etching mask; (E) removing the first resist pattern; (F) forming a second resist film on the light shielding film pattern; (G) forming a second resist pattern on a peripheral edge portion outside a region in which the circuit pattern of the phase shift film is formed by patterning the second resist film; (H) removing the light shielding film pattern in the region in which the circuit pattern of the phase shift film is formed by dry etching using a chlorine (Cl) -based gas containing oxygen (O) using the second resist pattern as an etching mask; and (I) removing the second resist pattern. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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