Phase shift mask blank and method for manufacturing a phase shift mask

Abstract

In a phase-shift mask blank comprising a phase-shift film and a light-shielding film formed in contact with the phase-shift film and made of a chromium-containing material, the phase-shift film is formed of a silicon-containing, carbon-free material, and the light-shielding film is formed of a chromium-containing, oxygen-nitrogen-carbon-carbon-containing material. The light-shielding film is configured to have a laminated structure consisting of four layers, a first layer, a second layer, a third layer, and a fourth layer, or a first layer, a third layer, a second layer, and a fourth layer, in order from the side away from the transparent substrate, with the first layer being the layer furthest from the transparent substrate and the fourth layer being the layer in contact with the phase-shift film. The second layer is a carbon-containing layer, and the fourth layer in contact with the phase-shift film is a carbon-free layer. [Effects] This invention enables the thinning of the resist film used in the manufacture of phase-shift masks, and provides a phase-shift mask that is less prone to haze generation and whose optical properties do not easily change even when washed with an aqueous solution containing sulfuric acid.

Description

[Technical Field]

[0001] The present invention relates to a phase shift mask blank, which is used as a material for a phase shift mask used in the manufacture of semiconductor devices and the like, and to a method for manufacturing a phase shift mask using a phase shift mask blank. [Background technology]

[0002] In recent years, with the miniaturization of semiconductor devices, and especially with the high integration of large-scale integrated circuits, high pattern resolution is required for projection lithography. Therefore, the phase shift method has been developed as a technique to improve the resolution of the transfer pattern in photomasks. The principle of the phase shift method is to adjust the phase of the transmitted light passing through the opening of the mask pattern (phase shift film pattern) so that it is inverted by approximately 180 degrees with respect to the phase of the transmitted light passing through the part adjacent to the opening. As a result, when the transmitted light interferes with each other, the light intensity at the boundary is weakened, and the resolution and depth of focus of the transfer pattern are improved. Photomasks that use this principle are called phase shift masks.

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

[0004] Specifically, as a method for manufacturing a phase-shift mask by forming a phase-shift film pattern from a phase-shift mask blank, first, a resist film is formed on a chromium (Cr)-containing film of the phase-shift mask blank. A pattern is drawn on the resist film using light or an electron beam, and the resist film is developed to form a resist pattern. Using the resist pattern as an etching mask, the chromium (Cr)-containing film is etched to form a chromium (Cr)-containing film pattern. Next, using the chromium (Cr)-containing film pattern as an etching mask, the phase-shift film is etched to form a phase-shift film pattern. Then, the resist pattern is removed with an aqueous solution containing sulfuric acid, for example, sulfuric acid peroxide (a mixture of sulfuric acid and hydrogen peroxide). Furthermore, to neutralize the film surface, it is washed with an aqueous solution containing a basic substance such as ammonia (NH3), and then the chromium (Cr)-containing film pattern is removed by etching.

[0005] When removing a chromium (Cr)-containing film pattern, it is common practice to leave a light-shielding film outside the area where the circuit pattern is formed in the phase-shift film pattern, so that the combined optical density (OD) of the phase-shift film and the light-shielding film is usually 3 or higher, thus creating a light-shielding area (light-shielding film pattern) at the outer edge of the phase-shift mask. This is to prevent unwanted exposure light from leaking and irradiating the resist film on adjacent chips located outside the circuit pattern when transferring the circuit pattern to the wafer using a wafer exposure apparatus. A common method for forming such a light-shielding area is to form a phase-shift film pattern, remove the resist pattern, then form a new resist film, and use the resist pattern formed by pattern drawing and development as an etching mask to etch the chromium (Cr)-containing film in the circuit pattern portion of the phase-shift film pattern, leaving the light-shielding area at the outer edge.

[0006] For phase-shift masks, where high-precision pattern formation is required, dry etching using gas plasma is the mainstream method. Dry etching of chromium (Cr) films is performed using chlorine (Cl)-based gas containing oxygen (O) (chlorine (Cl) dry etching), while dry etching of films containing molybdenum (Mo) and silicon (Si) is performed using fluorine (F)-based gas (fluorine (F) dry etching). In particular, for dry etching of chromium (Cr) films, it is known that using an etching gas mixed with 10 to 25 volume percent of oxygen gas (O2 gas) to chlorine (Cl)-based gas increases chemical reactivity and improves the etching rate.

[0007] As circuit patterns become smaller, technologies for forming fine phase-shift film patterns on phase-shift masks are required. In particular, the line patterns of the assist patterns, which help improve the resolution of the main pattern of the phase-shift mask, need to be formed smaller than the main pattern so that they are not transferred to the wafer when the circuit pattern is transferred to the wafer using a wafer exposure apparatus. In a generation of phase-shift masks where the pitch of the line-and-space pattern of the main pattern on the wafer is 10 nm, the line-and-space pattern of the assist pattern on the phase-shift mask needs to have a line width of about 40 nm.

[0008] On the other hand, chemically amplified resists, used to form photomask patterns such as phase-shift film patterns, consist of a base resin, an acid generator, a surfactant, etc., and many reactions in which the acid generated by exposure acts as a catalyst can be applied, making high sensitivity possible. Chemically amplified resists enable the formation of mask patterns such as fine phase-shift film patterns with line widths of 200 nm or less. However, even with chemically amplified resists, as the pattern width is narrowed, the fine line patterns begin to collapse due to collisions with the developer during the development process, reaching the resolution limit.

[0009] Regarding the thinning of the resist film, for example, in the method described in International Publication No. 2010 / 038445 (Patent Document 1), in order to form a fine pattern, the film for forming the mask pattern is a film containing molybdenum (Mo) and silicon (Si) that can be made thin, and an etching mask film is formed on this film. The etching mask film is a film containing chromium and carbon, such as a film made of chromium oxide carbide nitride, which has a high etching rate, thereby thinning the resist film and reducing the deformation of the resist pattern.

[0010] In etching using a resist film (resist pattern), the resist pattern is also etched to some extent during etching. If the resist pattern disappears, defects such as pinholes will occur in the film below the resist pattern (on the transparent substrate side). Therefore, the thickness of the resist film must be such that the resist pattern remains at a predetermined thickness after etching. In the method described in International Publication No. 2010 / 038445 (Patent Document 1), the film for forming the mask pattern is a film containing molybdenum (Mo), and the etching mask film is a film containing chromium and carbon, which has a relatively high etching rate and can be made thin. By shortening the etching time of the chromium-containing film, the resist film is made thinner, and the LER (Line Edge Roughness) is further reduced. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] International Publication No. 2010 / 038445 [Patent Document 2] Japanese Patent Publication No. 2008-51880 [Overview of the project] [Problems that the invention aims to solve]

[0012] In the manufacturing process of advanced semiconductor devices, a protective component called a pellicle is used on photomasks to prevent pattern transfer defects caused by the adhesion of foreign matter. The pellicle consists of a transparent film that transmits exposure light and a frame to which the transparent film is attached. By attaching the pellicle to the photomask, it is possible to prevent foreign matter from adhering to the surface of the photomask. However, even with a photomask fitted with a pellicle, the cumulative amount of exposure light can cause foreign matter (growth foreign matter) called haze to be generated on the surface of the photomask, leading to a problem of pattern transfer defects. In the manufacturing process of advanced semiconductor devices, with the miniaturization of circuit patterns, the exposure light has changed from a 248nm KrF excimer laser to a shorter wavelength 193nm ArF excimer laser. However, the higher the energy (shorter the wavelength of the exposure light), the more pronounced the generation of haze becomes.

[0013] When haze occurs on a photomask, it acts as an obstruction (defect) to the exposure light, making it impossible to form the desired pattern on the wafer with a hazy photomask. If haze occurs, the pellicle must be removed, the photomask cleaned, and the haze removed. Furthermore, after cleaning, it is necessary to confirm that the haze has been completely removed using a photomask pattern inspection device. Therefore, the occurrence of haze significantly reduces productivity in the semiconductor device manufacturing process.

[0014] In particular, in the manufacturing of memory devices, a single photomask is used to expose more than 100,000 wafers. Therefore, the cumulative amount of exposure light emitted by photomasks used in the manufacturing of memory devices is greater than that of photomasks used in the manufacturing of logic devices. In wafer exposure for semiconductor device manufacturing, the amount of exposure light emitted in a single exposure is 10-20 mJ / cm² when the exposure light is from an ArF excimer laser. 2 However, since the circuit pattern of the photomask is exposed multiple times on a single wafer, if one photomask is used to expose more than 100,000 wafers, the cumulative exposure light dose to the photomask will be several tens of kJ / cm². 2 This is the result.

[0015] The cause of haze generation is that in the manufacturing process of a photomask, sulfate ions (SO4 2- ), which are acidic substances contained in an aqueous solution containing sulfuric acid used for cleaning to remove a resist pattern, remain on the surface of the film. Further, subsequently, basic ions (for example, when the basic substance is ammonia (NH3), ammonium ions (NH4 + )) contained in an aqueous solution containing a basic substance such as ammonia (NH3) used for neutralizing the surface of the film remain on the surface of the film. They react by irradiation of exposure light to form a salt (for example, ammonium sulfate ((NH4)2SO4)), and it is considered that one of the causes is that the salt grows into a solid (granular) by cumulative irradiation amount of exposure light (see, for example, Japanese Patent Application Laid-Open No. 2008-51880 (Patent Document 2)).

[0016] The present invention has been made to solve the above problems, and provides a phase shift mask blank capable of thinning a resist film and suppressing the generation of haze due to cumulative irradiation amount of exposure light, and also provides a method for manufacturing a phase shift mask from such a phase shift mask blank.

Means for Solving the Problems

[0017] When a circuit pattern is formed on a phase shift film which is a film for forming a circuit pattern, and a film containing chromium (Cr) is formed in contact with the circuit pattern (phase shift film pattern), even if the film containing chromium (Cr) is removed from above the phase shift film pattern by dry etching using a chlorine (Cl)-based gas containing oxygen (O), chromium (Cr) may remain on the surface of the phase shift film pattern. When chromium (Cr) remains on the surface of the phase shift film pattern, it reacts by irradiation of exposure light to become a chromium (Cr) compound such as chromium oxide (CrO), and haze is generated by further growth of the chromium (Cr) compound such as chromium oxide (CrO) into a solid (granular).

[0018] In particular, when the phase shift film contains a transition metal such as molybdenum (Mo) and the film containing chromium (Cr) contains carbon (C), a transition metal such as molybdenum (Mo) and carbon (C) react at the interface of the two films to form a transition metal carbide such as molybdenum carbide (MoC). Transition metal carbides with high melting points and high hardness are difficult to etch using a chlorine (Cl)-based gas containing oxygen (O), and are also difficult to remove by cleaning.

[0019] In particular, molybdenum carbide (MoC) is hardly etched using a chlorine (Cl)-based gas containing oxygen (O), so it is difficult to completely remove. Therefore, after forming the phase shift film pattern, transition metal carbides such as molybdenum carbide (MoC) are incorporated and remain on the phase shift film pattern, and haze due to chromium (Cr) compounds such as chromium oxide (CrO) derived from chromium (Cr) becomes prominent. In this case, chromium (Cr) compounds such as chromium oxide (CrO) spread not only on the phase shift film pattern (line pattern) but also to the space pattern (portion where no circuit pattern exists, for example, on a transparent substrate) adjacent to the phase shift film pattern due to the accumulation of the exposure light irradiation amount, and haze also occurs on the space pattern.

[0020] On the other hand, if the phase-shift film contains silicon (Si) and the chromium (Cr) film contains carbon (C), silicon (Si) and carbon (C) react at the interface between the two films to form silicon carbide (SiC). In this case, during the manufacturing process of the phase-shift mask, when a phase-shift film pattern is formed and the chromium (Cr) film is removed from the phase-shift film pattern by dry etching using a chlorine (Cl)-based gas containing oxygen (O), silicon carbide (SiC) is hardly etched by dry etching using a chlorine (Cl)-based gas containing oxygen (O), and therefore silicon carbide (SiC) remains on the surface of the phase-shift film pattern. Because silicon carbide (SiC) is readily soluble in aqueous solutions containing sulfuric acid, when an aqueous solution containing sulfuric acid, used to remove the resist film used to form a light-shielding area (light-shielding film pattern) on the outer edge of the phase-shift film, and also used to clean the phase-shift mask, comes into contact with silicon carbide (SiC) remaining on the surface of the phase-shift film pattern, the silicon (SiC) dissolves and is removed, changing the optical properties (phase difference, transmittance, etc.) of the phase-shift film pattern.

[0021] As a result of diligent research to solve the above problems, the present inventors have found a phase shift mask blank comprising a phase shift film and a light-shielding film formed in contact with the phase shift film and made of a material containing chromium (Cr), wherein the phase shift film is made of a material containing silicon (Si) but not carbon (C), and the light-shielding film is made of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), and the light-shielding film comprises four layers, arranged in order from the side away from the transparent substrate as a first layer, a second layer, a third layer, and a fourth layer, or four layers, as well as a first layer, a third layer, a second layer, and a fourth layer. Furthermore, we have found that a phase shift mask blank configured to have a laminated structure in which the first layer is the layer furthest from the transparent substrate and the fourth layer is the layer in contact with the phase shift film, wherein the second layer in the laminated structure is a carbon (C)-containing layer and the fourth layer is a carbon (C)-free layer, allows for the thinning of the resist film used in the manufacture of the phase shift mask, and that the phase shift mask obtained from the phase shift mask blank is less prone to haze generation and the optical properties of the phase shift film do not change easily even when washed with an aqueous solution containing sulfuric acid, thus leading to the present invention.

[0022] Accordingly, the present invention provides the following phase shift mask blank and a method for manufacturing a phase shift mask. 1. Transparent substrate and, A phase-shift film is provided on the transparent substrate and is formed of a material containing silicon (Si) but not carbon (C), A light-shielding film is provided on the side of the phase-shift film that is separated from the transparent substrate, and is made of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C). A phase shift mask blank comprising, The above light-shielding film has a laminated structure consisting of four layers, a first layer, a second layer, a third layer, and a fourth layer, arranged in order from the side separated from the transparent substrate, or a first layer, a third layer, a second layer, and a fourth layer. In the above laminated structure, the first layer is the layer furthest from the transparent substrate, and the fourth layer is the layer in contact with the phase-shift film. The above-mentioned first layer contains chromium (Cr) and oxygen (O), with a chromium (Cr) content of 28 atomic% to 40 atomic%, an oxygen (O) content of 47 atomic% to 60 atomic%, and a thickness of 1 nm to 4 nm. The above-mentioned second layer contains chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), with a chromium (Cr) content of 30 atomic% to 45 atomic%, an oxygen (O) content of 28 atomic% to 40 atomic%, a nitrogen (N) content of 12 atomic% to 24 atomic%, a carbon (C) content of 5 atomic% to 15 atomic%, and a thickness of 18 nm to 24 nm. The above third layer contains chromium (Cr) and nitrogen (N), with a chromium (Cr) content of 50 atomic% to 60 atomic%, a nitrogen (N) content of 20 atomic% to 40 atomic%, and a thickness of 1 nm to 6 nm. The above fourth layer contains chromium (Cr), oxygen (O), and nitrogen (N), but does not contain carbon (C), with a chromium (Cr) content of 35 atomic% to 44 atomic%, an oxygen (O) content of 42 atomic% to 54 atomic%, a nitrogen (N) content of 2 atomic% to 20 atomic%, and a thickness of 18 nm to 36 nm. A phase-shift mask blank characterized by the following features. 2. The phase-shift mask blank according to claim 1, characterized in that the zeta potential of the phase-shift membrane is between -15mV and +15mV when the pH is between 3 and 4, and between -60mV and +10mV when the pH is between 5 and 6. 3. The above first layer contains nitrogen (N), and the nitrogen (N) content is between 5 atomic percent and 25 atomic percent. The above third layer contains oxygen (O), and the oxygen (O) content is between 6 atomic percent and 30 atomic percent. A phase shift mask blank according to claim 1, characterized in that it is a phase shift mask blank. 4. The phase shift mask blank according to claim 1, characterized in that the material used to form the phase shift film contains nitrogen (N). 5. The phase shift mask blank according to claim 1, characterized in that the material used to form the phase shift film does not contain a transition metal. 6. The phase shift mask blank according to claim 1, characterized in that the total sheet resistance of the first, second, third, and fourth layers of the light-shielding film is 350 kΩ / □ or less. 7. The phase-shift mask blank according to claim 1, characterized in that the phase difference of the phase-shift film with respect to exposure light, which is an ArF excimer laser (wavelength 193 nm), is 175 degrees or more and 185 degrees or less, the transmittance is 6% or more and 30% or less, and the thickness of the phase-shift film is 60 nm or more and 85 nm or less. 8. The phase-shift mask blank according to claim 1, characterized in that the combined optical density (OD) of the phase-shift film and the light-shielding film with respect to exposure light from an ArF excimer laser (wavelength 193 nm) is 3 or more. 9. The phase-shift mask blank according to 8, characterized in that the thickness of the light-shielding film is 48 nm or more and 54 nm or less. A method for manufacturing a phase shift mask having the circuit pattern of the phase shift film from a phase shift mask blank described in any one of sections 10.1 to 9, (A) A step of forming a first resist film on the above light-shielding film, (B) A step of patterning the first resist film to form a first resist pattern, (C) A step of forming a light-shielding film pattern by patterning the light-shielding film using the first resist pattern described above as an etching mask, by dry etching with a chlorine (Cl)-based gas containing oxygen (O), (D) Using the above light-shielding film pattern as an etching mask, the above phase-shift film is patterned by dry etching using a fluorine (F)-based gas to form a phase-shift film pattern, (E) A step of removing the first resist pattern described above, (F) A step of forming a second resist film on the above light-shielding film pattern, (G) A step of patterning the second resist film to form a second resist pattern on the outer peripheral edge located outside the region where the circuit pattern of the phase shift film is formed, (H) Using the second resist pattern described above as an etching mask, the light-shielding film pattern in the region where the circuit pattern of the phase-shift film is formed is removed by dry etching using a chlorine (Cl) gas containing oxygen (O), (I) A step of removing the second resist pattern described above A method for manufacturing a phase shift mask, characterized by including the following: [Effects of the Invention]

[0023] The phase-shift mask blank of the present invention allows for the thinning of the resist film used in the manufacture of the phase-shift mask, and provides a phase-shift mask that is less prone to haze generation and whose optical properties do not easily change even when washed with an aqueous solution containing sulfuric acid. [Brief explanation of the drawing]

[0024] [Figure 1] This is a cross-sectional view showing an example of a phase-shift mask blank of the present invention. [Figure 2] This is a cross-sectional view showing an example of the phase shift mask of the present invention. [Figure 3] This is a cross-sectional view showing another example of the phase-shift mask blank of the present invention. [Figure 4] This is a cross-sectional view showing another example of the phase shift mask of the present invention. [Modes for carrying out the invention]

[0025] The present invention will be described in more detail below. The phase-shift mask blank of the present invention comprises a transparent substrate, a phase-shift film provided on the transparent substrate, and a light-shielding film provided in contact with the phase-shift film on the side of the phase-shift film that is spaced away from the transparent substrate. The light-shielding film has a laminated structure consisting of four layers, in order from the side spaced away from the transparent substrate: a first layer, a second layer, a third layer, and a fourth layer, or a first layer, a third layer, a second layer, and a fourth layer.

[0026] The phase-shift mask blank of the present invention can be used to manufacture a phase-shift mask having a circuit pattern of a phase-shift film (phase-shift film pattern) 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 edge of the phase-shift mask, formed from a light-shielding film in contact with the phase-shift film outside the region (effective region) where the circuit pattern of the phase-shift film is formed.

[0027] The phase shift mask blank and phase shift mask manufactured from the phase shift mask blank of the present invention are suitable as phase shift mask blanks and phase shift masks that use light with a wavelength of 200 nm or less, such as an ArF excimer laser (wavelength 193 nm), as exposure light.

[0028] The phase shift mask blank and phase shift mask of the present invention will be described below with reference to the drawings. In some cases, identical components will be given the same reference numerals and their description may be omitted. Also, for convenience, the drawings may be shown in an enlarged form, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0029] Figure 1 is a cross-sectional view showing an example of a phase shift mask blank of the present invention. This phase shift mask blank 101 comprises 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 the side of the phase shift film 2 that is separated from the transparent substrate 1. The light-shielding film 3 has a laminated structure 30 consisting of four layers, in order from the side separated from the transparent substrate 1: a first layer 31, a second layer 32, a third layer 33, and a fourth layer 34.

[0030] A phase shift mask as shown in Figure 2 can be manufactured from the phase shift mask blank shown in Figure 1. Figure 2 is a cross-sectional view showing an example of the phase shift mask of the present invention. This phase shift mask 102 comprises 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 at the outer peripheral edge of the main surface of the transparent substrate on the side of the phase shift film pattern 2a that is spaced away from the transparent substrate 1, and a circuit pattern is formed within the effective region 4. The light-shielding film pattern 3a has a laminated structure 30 consisting of four layers, in order from the side spaced away from the transparent substrate 1: a first layer 31, a second layer 32, a third layer 33, and a fourth layer 34.

[0031] In Figures 1 and 2, the first layer 31 is in contact with the second layer 32 and is the layer furthest from the transparent substrate 1. The second layer 32 is in contact with the first layer 31 and the third layer 33. The third layer 33 is in contact with the second layer 32 and the fourth layer 34. The fourth layer 34 is in contact with the third layer 33 and the phase-shift film 2.

[0032] Figure 3 is a cross-sectional view showing another example of the phase shift mask blank of the present invention. This phase shift mask blank 103 comprises 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 the side of the phase shift film 2 that is spaced away from the transparent substrate 1. The light-shielding film 3 has a laminated structure 30 consisting of four layers, in order from the side spaced away from the transparent substrate 1: a first layer 31, a third layer 33, a second layer 32, and a fourth layer 34.

[0033] A phase shift mask as shown in Figure 4 can be manufactured from the phase shift mask blank shown in Figure 3. Figure 4 is a cross-sectional view showing another example of the phase shift mask of the present invention. This phase shift mask 104 comprises 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 at the outer peripheral edge of the main surface of the transparent substrate on the side of the phase shift film pattern 2a that is spaced away from the transparent substrate 1, and a circuit pattern is formed within the effective region 4. The light-shielding film pattern 3a has a laminated structure 30 consisting of four layers in order from the side spaced away from the transparent substrate 1: a first layer 31, a third layer 33, a second layer 32, and a fourth layer 34.

[0034] In Figures 3 and 4, the first layer 31 is in contact with the third layer 33 and is the layer furthest from the transparent substrate 1. The third layer 33 is in contact with the first layer 31 and the second layer 32. The second layer 32 is in contact with the third layer 33 and the fourth layer 34. The fourth layer 34 is in contact with the second layer 32 and the phase-shift film 2.

[0035] As for the transparent substrate, there are no particular restrictions on the type or size of any substrate that is transparent at the wavelength used as the exposure wavelength; for example, a quartz substrate such as a synthetic quartz substrate can be used. As a transparent substrate, for example, a substrate called a 6025 substrate, which has a size of 6 inches square and a thickness of 0.25 inches as specified in the SEMI standard, is preferred. When using the SI system, the size of a 6025 substrate is usually expressed as 152 mm square and 6.35 mm thick.

[0036] In the present invention, the phase-shift film may be formed in contact with the transparent substrate, or it may be formed on the transparent substrate via one or more other films. The phase-shift film may be a single layer film, a multilayer film (for example, a film composed of two, three, or four layers), or a film having a gradient composition.

[0037] The phase shift film is preferably a halftone phase shift film. When the phase shift film is a halftone phase shift film, the phase shift mask blank and the phase shift mask become a halftone phase shift mask blank and a halftone phase shift mask, respectively.

[0038] The phase-shift film is formed from a material that contains silicon (Si) but does not contain carbon (C). The silicon-containing material that does not contain carbon (C) preferably contains either oxygen (O) or nitrogen (N), or both, particularly nitrogen (N). The silicon-containing material that does not contain carbon (C) in the phase-shift film may also contain hydrogen (H).

[0039] Examples of silicon (Si)-containing, carbon (C)-free materials for phase-shift films include silicon (Si) compounds containing silicon (Si) and either or both oxygen (O) and nitrogen (N). Specific examples of silicon (Si) compounds include materials composed of silicon (Si) and nitrogen (N) (silicon nitride (SiN)), and materials composed of silicon (Si), oxygen (O), and nitrogen (N) (silicon oxidizate (SiON)).

[0040] Materials containing silicon (Si) but not carbon (C) preferably do not contain chromium (Cr). Materials containing silicon (Si) but not carbon (C) may contain transition metals other than chromium (Cr), but if they do, the content of the transition metals other than chromium (Cr) is preferably 6 atomic% or less, more preferably 4 atomic% or less, on average across the entire film.

[0041] Furthermore, in materials containing silicon (Si) but not carbon (C) in a phase-shift film, materials containing a transition metal (Me) other than chromium (Cr) include transition metal silicon (MeSi) compounds that contain a transition metal (Me) and silicon (Si), or transition metal (Me), silicon (Si), and one or both of nitrogen (N) and oxygen (O). Specifically, examples of transition metal silicon (MeSi) compounds include materials consisting of a transition metal (Me), silicon (Si), and nitrogen (N) (transition metal silicon nitride (MeSiN)), and materials consisting of a transition metal (Me), silicon (Si), oxygen (O), and nitrogen (N) (transition metal silicon oxidizate (MeSiON)).

[0042] Other transition metals (Me) besides chromium (Cr) include molybdenum (Mo), tungsten (W), tantalum (Ta), titanium (Ti), zirconium (Zr), and hafnium (Hf).

[0043] Materials containing silicon (Si) but not carbon (C) preferably do not contain transition metals. If the silicon (Si)-containing, carbon-free material forming the phase-shift film does not contain transition metals, even if carbon (C) from the light-shielding film containing chromium (Cr) reaches the interface between the phase-shift film and the light-shielding film, there will be no reaction between the transition metal and carbon (C) at the interface between the phase-shift film and the light-shielding film, and transition metal carbides will not be formed. Therefore, after removing the light-shielding film from the phase-shift film pattern, transition metal carbides such as molybdenum carbide (MoC) will not incorporate chromium (Cr) and remain, and the haze generated by the incorporation of chromium (Cr) by transition metal carbides such as molybdenum carbide (MoC) and remaining will be suppressed.

[0044] Preferably, the phase-shift film is made of a material that is resistant to dry etching using oxygen (O)-containing chlorine (Cl)-based gases and can be removed by dry etching using fluorine (F)-based gases.

[0045] In the present invention, a typical example of dry etching using a chlorine (Cl)-based gas containing oxygen (O) is dry etching using a mixed gas of chlorine gas (Cl2 gas) and oxygen gas (O2 gas) (for example, a gas obtained by mixing 10 to 25 volume percent of oxygen gas (O2 gas) with chlorine gas (Cl2 gas)). On the other hand, in the present invention, a typical example of dry etching using a fluorine (F)-based gas is dry etching using a gas containing carbon tetrafluoride gas (CF4 gas) or sulfur hexafluoride gas (SF6 gas).

[0046] In the present invention, it is preferable that the phase-shift film has a zeta potential within a predetermined range. The zeta potential is an indicator of the degree of charging (the phenomenon of charge accumulation) on the surface of the film. When the zeta potential is zero (0), the protons (hydrogen cations) on the surface of the film and the charge in the film are equal, and the film is electrically neutral. On the other hand, when the zeta potential is negative (-), there are fewer protons on the surface of the film than the charge in the film, and the film is electrically negative. When the zeta potential is positive (+), there are more protons on the surface of the film than the charge in the film, and the film is electrically positive.

[0047] In the present invention, it is preferable that the phase-shift film has a zeta potential within a predetermined range when the pH is between 3 and 4. In the manufacturing process of a phase-shift mask, an aqueous solution containing sulfuric acid, such as sulfuric acid peroxide (usually with a pH of 4 or less), is usually used to remove the resist pattern. However, if the zeta potential of the phase-shift film with a pH between 3 and 4 is close to an electrically neutral state, sulfate ions (SO4) contained in the aqueous solution containing sulfuric acid are absorbed. 2- Because sulfate ions (SO4) are not easily attracted to the surface of the film, sulfate ions (SO4) are less likely to be attracted to the surface of the phase-shift film. 2- ) is less likely to remain. In particular, a phase-shift film formed from a material containing silicon (Si) but not transition metals is advantageous because the zeta potential at a pH of 3 to 4 is close to an electrically neutral state.

[0048] The zeta potential of the phase shift film at a pH of 3 or more and 4 or less is specifically preferably -15 mV or more, more preferably -10 mV or more, and is preferably +15 mV or less, more preferably +10 mV or less.

[0049] In addition, in the present invention, it is preferable that the zeta potential of the phase shift film at a pH of 5 or more and 6 or less is within a predetermined range. In the manufacturing process of the phase shift mask, after using an aqueous solution containing sulfuric acid such as sulfuric acid peroxide to peel the resist pattern, an aqueous solution containing ammonia (NH3) (usually having a pH of 5 or more) is usually used to neutralize the surface of the film. However, when the zeta potential of the phase shift film at a pH of 5 or more and 6 or less is close to a state of weakly negative to neutral electrically, ammonium (NH4 + ) is difficult to adhere to the surface of the film, so ammonium (NH4 + ) is difficult to remain on the surface of the phase shift film. In particular, a phase shift film formed of a material containing silicon (Si) and not containing a transition metal is advantageous because the zeta potential at a pH of 5 or more and 6 or less is close to a state of weakly negative to neutral electrically.

[0050] The zeta potential of the phase shift film at a pH of 5 or more and 6 or less is specifically preferably -60 mV or more, more preferably -30 mV or more, and is preferably +10 mV or less, more preferably +5 mV or less. The higher the zeta potential at a pH of 5 or more and 6 or less (the more on the positive (+) side), the more ammonium (NH4 + ) repels the surface of the film, making it difficult to be attracted to the surface of the film. However, if ammonium (NH4 + ) is not attracted to the surface of the film, ammonium (NH4 + ) does not react with sulfate ions (SO4 2- ), making it difficult to neutralize the surface of the film. Therefore, it is effective to set the upper limit of the zeta potential at a pH of 5 or more and 6 or less as described above.

[0051] By setting the zeta potential of the phase-shift membrane to a predetermined range for pH 3 to 4 and pH 5 to 6, sulfate ions (SO4) contained in an aqueous solution containing sulfuric acid are detected. 2- ) and ammonium (NH4) contained in aqueous solutions containing ammonia (NH3) + ) becomes less likely to remain on the surface of the phase-shift film. As a result, sulfate ions (SO4 2- ) and ammonium (NH4 + The reaction of ) by exposure light to form salts (ammonium sulfate ((NH4)2SO4)) is suppressed, and furthermore, the accumulation of exposure light reduces the generation of haze in which the salts grow into solid (granular) particles.

[0052] The phase difference of the phase-shift film with respect to exposure light (specifically, light with a wavelength of 200 nm or less, such as an ArF excimer laser (wavelength 193 nm)) is preferably 175 degrees or more and 185 degrees or less. Furthermore, the transmittance of the phase-shift film with respect to exposure light (specifically, light with a wavelength of 200 nm or less, such as an ArF excimer laser (wavelength 193 nm)) is preferably 6% or more and 30% or less, which provides a high effect in improving the resolution and depth of focus of the transfer pattern due to the phase-shift effect depending on the exposure conditions. The thickness of the phase-shift film is preferably 60 nm or more, more preferably 62 nm or more, and also preferably 85 nm or less, more preferably 78 nm or less, from the viewpoint of keeping the phase difference and transmittance within a predetermined range.

[0053] In the present invention, the light-shielding film is formed in contact with the phase-shift film. The light-shielding film may also be a film having a gradient composition. The light-shielding film has a laminated structure consisting of four layers, a first layer, a second layer, a third layer, and a fourth layer, in order from the side away from the transparent substrate, or a first layer, a third layer, a second layer, and a fourth layer. The laminated structure may consist of five or more layers, for example, five or six layers, but it is preferable that it consists only of a laminated structure consisting of four layers, a first layer, a second layer, a third layer, and a fourth layer, or a first layer, a third layer, a second layer, and a fourth layer. When the light-shielding film consists of five or more layers, the layers other than the first, second, third, and fourth layers are provided in the laminated structure at any position between the first and fourth layers.

[0054] In dry etching where a phase-shift film is the workpiece, it is preferable that the light-shielding film pattern formed by patterning the light-shielding film can be used as an etching mask when forming a phase-shift film pattern from the phase-shift film. Therefore, it is preferable that the light-shielding film is made of a material that is resistant to dry etching using fluorine (F)-based gases and can be removed by dry etching using chlorine (Cl)-based gases containing oxygen (O).

[0055] The light-shielding film is formed from a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) as a whole. By forming the light-shielding film from a material containing carbon (C), the etching rate of the light-shielding film in dry etching using a chlorine (Cl)-based gas containing oxygen (O) is increased. This allows for a reduction in the etching time (clear time) of the entire light-shielding film while ensuring the required light-shielding properties (optical density (OD)) as a whole, thus enabling the thinning of the resist film used when manufacturing a phase-shift mask from a phase-shift mask blank. It is preferable that the light-shielding film does not contain silicon (Si). Furthermore, it is preferable that the light-shielding film does not contain any transition metals other than chromium (Cr).

[0056] The materials forming the first, second, third, and fourth layers that constitute the laminated structure of the light-shielding film, as well as the materials forming the other layers, preferably contain chromium (Cr) as an essential component, and further preferably contain one or more selected from oxygen (O), nitrogen (N), and carbon (C), particularly oxygen (O) and nitrogen (N), or both. At least one layer selected from the first, second, and third layers, particularly the second layer, preferably contains carbon (C). On the other hand, the fourth layer does not contain carbon (C). Furthermore, at least one layer selected from the first, second, and fourth layers, particularly one or both of the first and fourth layers, preferably have a relatively high oxygen (O) content. By configuring the first, second, third, and fourth layers in this manner, the required light-shielding properties (optical density (OD)) for the entire light-shielding film can be ensured, while the etching time (clear time) for the entire light-shielding film in dry etching using a chlorine (Cl) gas containing oxygen (O) can be shortened. Furthermore, the haze and changes in optical properties that occur in the phase-shift film pattern due to the light-shielding film being a single layer containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) can be suppressed.

[0057] Specific examples of materials that form the first, second, third, and fourth layers of the light-shielding film's laminated structure, as well as materials that form the other layers, include 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) and oxygen (O) and nitrogen (N) (chromium oxide nitride (CrON)), materials composed of chromium (Cr) and oxygen (O) and carbon (C) (chromium oxide carbide (CrOC)), materials composed of chromium (Cr) and nitrogen (N) and carbon (C) (chromium nitride carbide (CrNC)), and materials composed of chromium (Cr) and oxygen (O) and nitrogen (N) and carbon (C) (chromium oxide nitride carbide (CrONC)).

[0058] 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.

[0059] The first layer is the layer furthest from the transparent substrate in the laminated structure. Typically, the first layer is the layer that comes into contact with the resist film when forming the resist film in contact with the light-shielding film during the manufacturing of a phase-shift mask from a phase-shift mask blank, and it is also the layer that comes into direct contact with the cleaning solution. Furthermore, in exposure using a phase-shift mask, it is the layer to which the exposure light directly enters. For this reason, the first layer is provided as a layer with good adhesion to the resist film, high chemical resistance to the cleaning solution, and low reflectivity to the exposure light.

[0060] The first layer contains chromium (Cr) and oxygen (O). Preferably, the first layer contains nitrogen (N). The first layer may contain a small amount of carbon (C), but it is preferable that it does not contain carbon (C). Specifically, materials that form the first layer include materials consisting of chromium (Cr) and oxygen (O), materials consisting of chromium (Cr), oxygen (O), and nitrogen (N), materials consisting of chromium (Cr), oxygen (O), and carbon (C), and materials consisting of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), with materials consisting of chromium (Cr), oxygen (O), and nitrogen (N) being preferred.

[0061] In the first layer, the chromium (Cr) content is preferably 28 atomic% or more, more preferably 30 atomic% or more, and also 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 also preferably 60 atomic% or less, more preferably 57 atomic% or less, and even more preferably 55 atomic% or less. If 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 also preferably 25 atomic% or less, and even more preferably 23 atomic% or less. If 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.

[0062] The thickness of the first layer can be any thickness that provides good adhesion to the resist film, chemical resistance to aqueous solutions used for cleaning, and a low reflectivity of the light-shielding film to exposure light, and can be formed relatively thinly among the first, second, third, and fourth layers. Furthermore, a thinner first layer allows for a more effective reduction of sheet resistance by the third layer, as described later, and allows for the use of a material with relatively low conductivity (relatively high sheet resistance) as the material for the first layer. The thickness of the first layer is preferably 1 nm or more, preferably 4 nm or less, and more preferably 3 nm or less.

[0063] The fourth layer is the layer in contact with the phase-shift film in the laminated structure. Therefore, the fourth layer is provided as a layer that does not contain carbon (C). By making the fourth layer a carbon-free layer, the reaction between silicon (Si) and carbon (C) at the interface between the silicon (Si)-containing phase-shift film and the light-shielding film, which occurs when the light-shielding film containing chromium (Cr) also contains carbon (C), does not occur, and silicon carbide (SiC) is not formed. Therefore, no silicon carbide (SiC) remains after the light-shielding film is removed from the phase-shift film pattern, and changes in the optical properties of the phase-shift film (phase difference, transmittance, etc.) caused by the presence of silicon carbide (SiC) are suppressed.

[0064] Furthermore, by making the fourth layer a carbon (C)-free layer, even if the phase shift film is formed from a material containing transition metals, the reaction between the transition metal and carbon (C) at the interface between the phase shift film containing transition metals and the light-shielding film, which occurs when the light-shielding film containing chromium (Cr) also contains carbon (C), does not occur, and transition metal carbides are not formed. Therefore, after removing the light-shielding film from the phase shift film pattern, transition metal carbides such as molybdenum carbide (MoC) do not incorporate chromium (Cr) and remain, and the haze caused by the incorporation of chromium (Cr) by transition metal carbides such as molybdenum carbide (MoC) is suppressed.

[0065] The fourth layer contains chromium (Cr), oxygen (O), and nitrogen (N). Specifically, a material consisting of chromium (Cr), oxygen (O), and nitrogen (N) is preferred as the material forming the fourth layer.

[0066] 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.

[0067] The thickness of the fourth layer is preferably such that carbon (C) contained in the layers other than the fourth layer does not reach the phase-shift film side. Furthermore, since the fourth layer has a relatively high optical density (OD) per unit thickness, it is preferable to form it relatively thicker than the first, second, third, and fourth layers from the viewpoint of obtaining the required light-shielding properties (optical density (OD)) for the light-shielding film as a whole. The thickness of the fourth layer is preferably 18 nm or more, more preferably 20 nm or more, and also preferably 36 nm or less, more preferably 34 nm or less.

[0068] To ensure a sufficient etching rate in dry etching of a light-shielding film using a chlorine (Cl)-based gas containing oxygen (O), it is preferable for the light-shielding film to contain carbon (C), and to increase the amount of carbon (C) contained in the light-shielding film. The inclusion of carbon (C) contributes to giving chromium (Cr)-containing materials etching properties similar to chromium carbide (CrN), which has a relatively low density and is easily etched by dry etching using a chlorine (Cl)-based gas containing oxygen (O). Therefore, a second layer is provided as a carbon (C)-containing layer. Furthermore, the inclusion of oxygen (O) in the light-shielding film contributes to improving the etching rate in dry etching using a chlorine (Cl)-based gas containing oxygen (O). Moreover, when forming a light-shielding film pattern from the light-shielding film by dry etching using a chlorine (Cl)-based gas containing oxygen (O), it is preferable for more oxygen (O) to be supplied from the light-shielding film to assist in plasma processing of minute space patterns, and therefore, the inclusion of oxygen (O) is effective.

[0069] The second layer contains chromium (Cr), oxygen (O), nitrogen (N), and carbon (C). Specifically, a material consisting of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) is preferred as the material forming the second layer.

[0070] In the second layer, the chromium (Cr) content is preferably 30 atomic% or more, more preferably 32 atomic% or more, and also 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 also 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 also 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 also preferably 15 atomic% or less, more preferably 12 atomic% or less.

[0071] Since the second layer has a relatively high optical density (OD) per unit thickness, it is preferable to form it relatively thick among the first, second, third, and fourth layers, from the viewpoint of obtaining the necessary light shielding properties (optical density (OD)) for the entire light-shielding film. In addition, since the second layer has a high etching rate, it is preferable to shorten the etching time (clear time) for the entire light-shielding film and to thin the resist film used when manufacturing a phase-shift mask from a phase-shift mask blank. Furthermore, a thinner second layer allows for a more effective reduction in sheet resistance by the third layer, as described later, and allows for the use of a material with relatively low conductivity (relatively high sheet resistance) 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 also preferably 24 nm or less, more preferably 20 nm or less.

[0072] When manufacturing a phase-shift mask from a phase-shift mask blank, a resist film is usually formed in contact with a light-shielding film. If the sheet resistance of the light-shielding film is high, when a pattern is drawn on the resist film using an electron beam, the surface of the light-shielding film may become charged by the electron beam, causing the irradiation position of the electron beam to shift, and the electron beam may not irradiate the film in the intended position. If the irradiation position of the electron beam shifts, the pattern will not be formed in the intended position, and as a result, the circuit of the manufactured device will not be formed correctly. Therefore, it is preferable for the sheet resistance of the light-shielding film to be low.

[0073] If 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 the composition has a relatively low chromium (Cr) content, the sheet resistance will be relatively high. Also, if the first, second, and fourth layers have an oxygen (O) rich composition with a relatively high oxygen (O) content, the sheet resistance of the first, second, and fourth layers will be relatively high because chromium oxide (CrO) has a higher sheet resistance than chromium nitride (CrN).

[0074] Therefore, from the viewpoint of lowering the overall sheet resistance of the light-shielding film, a third layer is provided that contains chromium (Cr) and nitrogen (N), with a relatively high chromium (Cr) content and no oxygen (O) content or a relatively low oxygen (O) content. Even if the sheet resistance of the first, second, and fourth layers is relatively high, the overall sheet resistance of the light-shielding film can be lowered by providing the third layer. The third layer may be provided on the fourth layer side relative to the second layer (i.e., in order from the side away from the transparent substrate, the layers are in the order of the first, second, third, and fourth layers) or on the first layer side (i.e., in order from the side away from the transparent substrate, the layers are in the order of the first, third, second, and fourth layers). However, from the viewpoint of high resolution when a resist film is formed on a light-shielding film in contact with an aqueous solution containing sulfuric acid to form a micro-pattern, it is preferable that the third layer be provided on the fourth layer side relative to the second layer.

[0075] 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 than chromium oxide (CrO) when dry etching is performed using a chlorine (Cl)-based gas containing oxygen (O). Therefore, from the viewpoint of lowering the overall sheet resistance of the light-shielding film while increasing the etching rate and shortening the overall etching time (clear time) of the light-shielding film, it is preferable that the third layer contains oxygen (O) to thin the resist film used when manufacturing a phase-shift mask from a phase-shift mask blank. The third layer may contain a small amount of carbon (C), but it is preferable that it does not contain carbon (C). Specific examples of materials that form the third layer include materials composed of chromium (Cr) and nitrogen (N), materials composed of chromium (Cr), nitrogen (N), and carbon (C), materials composed of chromium (Cr), oxygen (O), and nitrogen (N), and materials composed of chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), with materials composed of chromium (Cr), oxygen (O), and nitrogen (N) being preferred.

[0076] In the third layer, the chromium (Cr) content is preferably 50 atomic% or more, more preferably 52 atomic% or more, and also 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 also 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 also 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.

[0077] From the viewpoint of shortening the etching time (clear time) of the entire light-shielding film, the thickness of the third layer is preferably formed to be relatively thin among the first, second, third, and fourth layers. However, from the viewpoint of lowering the sheet resistance of the entire light-shielding film, a certain thickness is necessary. The thickness of the third layer is preferably 1 nm or more, more preferably 2 nm or more, and also preferably 6 nm or less, more preferably 4 nm or less.

[0078] In a light-shielding film, the overall sheet resistance of all layers in the laminated structure except for the fourth layer (or the first, second, third, and third layers if the laminated structure consists of the first, second, third, and fourth layers), preferably all layers (or the first, second, third, and fourth layers if the laminated structure consists of the first, second, third, and fourth layers, preferably the first, second, third, and fourth layers), is preferably 350 kΩ / □ or less, more preferably 300 kΩ / □ or less, and even more preferably 250 kΩ / □ or less.

[0079] In particular, the light-shielding film is preferably configured such that the light-shielding film pattern is used as a hard mask for etching the phase-shift film, and then a portion of the light-shielding film pattern is left on the phase-shift film to form a phase-shift mask. Specifically, it is preferable that the light-shielding film pattern is left in contact with the phase-shift film outside the region (effective region) where the circuit pattern of the phase-shift film pattern is formed, and that this portion serves as a light-shielding portion at the outer edge of the phase-shift mask, thus forming the phase-shift mask.

[0080] When the light-shielding film forms a light-shielding portion (light-shielding film pattern) on the outer edge of the phase-shift mask, the combined optical density (OD) of the phase-shift film and the light-shielding film with respect to exposure light (specifically, light with a wavelength of 200 nm or less, such as an ArF excimer laser (wavelength 193 nm)) is preferably greater than 2, more preferably 2.5 or higher, and even more preferably 3 or higher. For example, if the phase-shift film has a transmittance of 6% to 30% with respect to exposure light (optical density (OD) of 0.53 to 1.22), in order for the combined optical density (OD) of the phase-shift film and the light-shielding film to be 3 or higher, the optical density (OD) of the light-shielding film with respect to exposure light must be 1.78 or higher. The upper limit of the optical density (OD) of the light-shielding film with respect to exposure light is usually 3.2 or lower.

[0081] The thickness of the light-shielding film (total thickness of the light-shielding film) is preferably 38 nm or more, more preferably 44 nm or more, and also 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 film forms the light-shielding portion (light-shielding film pattern) on the outer edge of the phase shift mask, the thickness of the light-shielding film (total thickness of the light-shielding film) is preferably 48 nm or more, and also preferably 54 nm or less.

[0082] The phase-shift mask blank of the present invention may further include a resist film in contact with the side of the light-shielding film that is separated 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 a chemically amplified resist is particularly preferred. The chemically amplified resist may be positive or negative, and examples include a base resin such as a hydroxystyrene resin or a (meth)acrylic acid resin, and an acid generator, with the addition of a crosslinking agent, quencher, surfactant, etc., as needed. The thickness of the resist film is preferably 200 nm or less, more preferably 150 nm or less, from the viewpoint of preventing the resist pattern from collapsing during the development process and the rinsing process after development when forming a fine pattern. If the thickness of the resist film is too thin, it may not be possible to form it to a stable thickness, so the thickness of the resist film is preferably 40 nm or more, more preferably 50 nm or more.

[0083] The formation of the phase-shift film and the light-shielding film (the layer constituting the light-shielding film) is not particularly limited, but formation by sputtering is preferred because it offers good controllability and makes it easy to form films with predetermined characteristics. The sputtering method can be DC sputtering, RF sputtering, etc., and is not particularly limited.

[0084] When forming a phase-shift film made of a material containing silicon (Si) but not carbon (C), a silicon (Si) target can be used as the sputtering target. If necessary, a transition metal target, preferably a transition metal other than chromium (Cr) (Me), or a target containing silicon (Si) and a transition metal, preferably a transition metal other than chromium (Cr) (Me), can be used. Sputtering may also be co-sputtering using multiple types of targets. In this case, cos-sputtering can be performed using a silicon (Si) target and a transition metal target, preferably a transition metal other than chromium (Cr) (Me), using multiple targets containing silicon (Si) and a transition metal, preferably a transition metal other than chromium (Cr) (Me), but with different compositions (some or all of the constituent elements are different, or the constituent elements are the same but their concentrations are different), or using a silicon (Si) target or a transition metal target, preferably a transition metal other than chromium (Cr) (Me), and a target containing silicon (Si) and a transition metal, preferably a transition metal other than chromium (Cr) (Me).

[0085] On the other hand, when forming a light-shielding film made of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) (when forming layers that constitute a light-shielding film), a chromium (Cr) target can be used as the sputtering target.

[0086] The power supplied to the sputtering target should be set appropriately depending on the size of the sputtering target, cooling efficiency, and ease of controlling film formation. Typically, the power per unit area of ​​the sputtering surface of the sputtering target is 0.1 to 10 W / cm². 2 That's all you need to do.

[0087] When a phase-shift film is formed from a material consisting only of silicon (Si) or silicon (Si) and a transition metal, only noble gases such as helium (He), neon (Ne), and argon (Ar) are used as sputtering gases. On the other hand, when a phase-shift film is formed from a material containing either or both oxygen (O) and nitrogen (N), reactive sputtering is preferred. In this case, noble gases such as helium (He), neon (Ne), and argon (Ar), along with reactive gases, are used as sputtering gases. For example, if the phase-shift film contains oxygen (O), oxygen (O2) gas should be used as the reactive gas; if the phase-shift film contains nitrogen (N), nitrogen (N2) gas should be used as the reactive gas. Furthermore, if the phase-shift film contains both oxygen (O) and nitrogen (N), oxygen gas (O2 gas) and nitrogen gas (N2 gas) may be used simultaneously as the reactive gas, or nitrogen oxide gases such as nitric oxide gas (NO gas), nitrogen dioxide gas (NO2 gas), and nitrous oxide gas (N2O gas) may be used.

[0088] On the other hand, when forming a light-shielding film (forming layers that constitute a light-shielding film) with a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), reactive sputtering is preferred. In this case, noble gases such as helium gas (He gas), neon gas (Ne gas), and argon gas (Ar gas), and reactive gases are used as sputtering gases. For example, if the layers constituting the light-shielding film contain oxygen (O), oxygen gas (O2 gas) may be used as the reactive gas; if the layers constituting the light-shielding film contain nitrogen (N), nitrogen gas (N2 gas) may be used as the reactive gas. If the layers constituting the light-shielding film contain both oxygen (O) and nitrogen (N), oxygen gas (O2 gas) and nitrogen gas (N2 gas) may be used simultaneously as the reactive gases, or nitrogen oxide gases such as nitric oxide gas (NO gas), nitrogen dioxide gas (NO2 gas), and nitrous oxide gas (N2O gas) may be used. Furthermore, if the light-shielding film contains carbon (C), an oxidizing carbon gas such as carbon monoxide (CO gas) or carbon dioxide (CO2 gas) can be used as the reactive gas.

[0089] The pressure during film formation should be set appropriately considering film stress, chemical resistance, and cleaning resistance. Typically, a pressure of 0.01 Pa or higher, more preferably 0.03 Pa or higher, preferably 1 Pa or lower, and more preferably 0.3 Pa or lower, improves chemical resistance. The flow rates of each gas should be set appropriately to achieve the desired composition, and are typically between 0.1 and 100 sccm.

[0090] In the manufacturing process of the phase shift mask blank, the transparent substrate or the transparent substrate and the film formed on the transparent substrate may be subjected to heat treatment. The heat treatment method can include infrared heating, resistance heating, etc., and there are no particular restrictions on the treatment conditions. The heat treatment can be carried out, for example, in a gas atmosphere containing oxygen (O). There are no particular restrictions on the concentration of the oxygen (O) gas; for example, in the case of oxygen gas (O2 gas), it can be 1 to 100 volume percent. The heat treatment temperature is preferably 200°C or higher, more preferably 400°C or higher. Furthermore, in the manufacturing process of the phase shift mask blank, the film formed on the transparent substrate, particularly the light-shielding film, may be subjected to ozone (O3) treatment or plasma treatment, and there are no particular restrictions on the treatment conditions. Any of these treatments can be carried out for the purpose of increasing the oxygen (O) concentration on the surface of the film, and in that case, the treatment conditions should be appropriately adjusted to achieve a predetermined oxygen (O) concentration. Furthermore, when forming a film by sputtering, it is possible to increase the oxygen (O) concentration on the surface of the film by adjusting the ratio of noble gases in the sputtering gas to oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), and other oxygen (O)-containing gases (oxidizing gases).

[0091] In the manufacturing process of phase-shift mask blanks, a cleaning treatment may be performed to remove particles present on the surface of the transparent substrate or the film formed on the transparent substrate. The cleaning can be performed using either or both ultrapure water and functional water, which is ultrapure water containing ozone gas (O3 gas), hydrogen gas (H2 gas), etc. Alternatively, after cleaning with ultrapure water containing a surfactant, further cleaning may be performed using either or both ultrapure water and functional water. The cleaning can be performed while irradiating with ultrasound as needed, and UV light irradiation can also be combined with the cleaning.

[0092] When forming a resist film on the photomask blank of the present invention, the method for forming the resist film is not particularly limited, and known methods such as spin coating can be applied.

[0093] A phase-shift mask can be manufactured from the phase-shift mask blank of the present invention by a general method without using a special development process or special dry etching. Furthermore, because the light-shielding film has a high etching rate relative to dry etching using a chlorine (Cl) gas containing oxygen (O), and the etching time (clear time) of the entire light-shielding film is short, a thin resist film can be formed, and a phase-shift mask can be manufactured by a general method. This suppresses the collapse of fine line patterns due to collisions with the developer during the resist film development process, and a good resolution limit can be achieved in the formation of the assist pattern line pattern, which assists the resolution of the main pattern of the phase-shift mask.

[0094] From the phase shift mask blank of the present invention, a phase shift mask can be manufactured that has a circuit pattern of a phase shift film and a light-shielding portion (light-shielding film pattern) in the peripheral edge region where the circuit pattern of the phase shift mask is not formed. Specifically, a phase shift mask having a circuit pattern of a phase shift film within the effective region of the phase shift mask and a light-shielding portion (light-shielding film pattern) in the peripheral edge region of the phase shift mask can be manufactured by a method including the following steps (A) to (I).

[0095] First, if necessary, a first resist film is formed on the light-shielding film (step (A)). If a resist film has not been formed on the phase-shift mask blank, a resist film is formed on the light-shielding film in contact with the light-shielding film in this step. If a phase-shift mask blank with a resist film already formed is used, this step is unnecessary. The first resist film can be the same as the resist film described above that is included in the phase-shift mask blank, and the thickness of the first resist film can also be the same as the resist film described above that is included in the phase-shift mask blank. The method for forming the resist film is not particularly limited, and known methods such as spin coating can be applied.

[0096] Next, the first resist film is patterned to form a first resist pattern (step (B)). The first resist pattern can be formed by drawing a pattern on the resist film with light or an electron beam using a known method and then developing it.

[0097] Next, using the first resist pattern as an etching mask, the light-shielding film is patterned by dry etching using a chlorine (Cl)-based gas containing oxygen (O) to form a light-shielding film pattern (step (C)).

[0098] Next, using the light-shielding film pattern as an etching mask, the phase-shift film is patterned by dry etching using a fluorine (F)-based gas to form a phase-shift film pattern (step (D)).

[0099] Next, the first resist pattern is removed (step (E)). The first resist pattern can be removed by washing with sulfuric acid peroxide (a mixture of sulfuric acid and hydrogen peroxide).

[0100] 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, in contact with the light-shielding film pattern, and also on the portion exposed after the phase-shift film has been removed (the transparent substrate, or any other film formed between the transparent substrate and the phase-shift film as needed), in contact with that portion. The second resist film can be the same as the resist film included in the phase-shift mask blank described above, and a resist film for laser writing is particularly preferred. The thickness of the second resist film is preferably 250 nm or more, and preferably 500 nm or less.

[0101] Next, the second resist film is patterned to form a second resist pattern on the outer peripheral edge located outside the region where the circuit pattern of the phase-shift film is formed (step (G)). The second resist pattern can be formed by drawing a pattern on the resist film with light or an electron beam using a known method and then developing it.

[0102] Next, using the second resist pattern as an etching mask, the light-shielding film pattern in the region where the circuit pattern of the phase-shift film is formed (effective region) is removed by dry etching using a chlorine (Cl)-based gas containing oxygen (O) (step (H)).

[0103] Next, the second resist pattern is removed (step (I)). The second resist pattern can be removed by washing with sulfuric acid peroxide (a mixture of sulfuric acid and hydrogen peroxide).

[0104] Preferably, the phase shift film pattern of the phase shift mask is such that its optical properties (phase difference, transmittance, etc.) do not change easily even when it comes into contact with an aqueous solution containing sulfuric acid, which is used to remove the resist film used to form a light-shielding portion (light-shielding film pattern) on the outer edge of the phase shift film during the process of manufacturing a phase shift mask from a phase shift mask blank, and also for cleaning the phase shift mask.

[0105] Therefore, when removing the resist film pattern as in step (I) described above, the change in the phase difference of the phase shift film when it comes into contact with an aqueous solution containing sulfuric acid (the change in the phase difference of the phase shift film relative to the set value in the phase shift 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. Furthermore, the change in the transmittance of the phase shift film (the change in the transmittance of the phase shift film relative to the set value in the phase shift mask blank state) is preferably 0.05% (percent points) or less, and more preferably 0.01% (percent points) or less.

[0106] Furthermore, when the phase shift mask is washed with an aqueous solution containing sulfuric acid, specifically a mixture of sulfuric acid and hydrogen peroxide (sulfuric acid:hydrogen peroxide solution = 3:1 (volume ratio)) at 100°C for 30 minutes, the change in the phase difference of the phase shift film is preferably 0.3 degrees or less, more preferably 0.2 degrees or less, and even more preferably 0.14 degrees or less. The change in the transmittance of the phase shift film is preferably 0.10% (percent points) or less, more preferably 0.05% (percent points) or less, and even more preferably 0.04% (percent points) 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.

[0107] The phase shift mask of the present invention is particularly effective in photolithography for forming a half-pitch pattern of 50 nm or less, preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less on a wafer (substrate to be processed), in which the pattern is transferred to a photoresist film formed on the wafer (substrate to be processed) using exposure light with a wavelength of 200 nm or less, such as an ArF excimer laser (wavelength 193 nm).

[0108] Using a phase-shift mask manufactured from the phase-shift mask blank of the present invention, the phase-shift mask pattern (photomask pattern) can be irradiated with exposure light to transfer the photomask pattern to a photoresist film formed on a wafer (substrate to be processed), which is the target of the photomask pattern exposure. The exposure light irradiation can be performed by dry exposure or immersion exposure, and is particularly suitable for exposure of wafers (substrates to be processed) of 300 mm or more by immersion exposure to expose the photomask pattern.

[0109] In a wafer exposure apparatus, exposure light is directed onto a phase-shift mask. In light-shielding film patterns, the exposure light is blocked. In circuit patterns (halftone phase-shift film patterns), in line patterns, a portion of the exposure light is blocked, and in space patterns, the blocked light passes through the transparent substrate and irradiates the photoresist film on the wafer (substrate to be processed). It is preferable that the phase-shift mask can be used for a long period of time without generating haze, even when the amount of exposure light irradiated onto the phase-shift film accumulates. From this viewpoint, the phase-shift mask should have a cumulative exposure light dose of 40 kJ / cm². 2 It is preferable that no haze occurs until the cumulative exposure dose reaches 50 kJ / cm². 2 It is preferable that no haze occurs until the exposure light dose reaches the above range. It is preferable that neither haze due to ammonium sulfate ((NH4)2SO4) or the above-mentioned haze, nor haze due to chromium oxide (CrO) or the above-mentioned haze, or both, occurs until the exposure light dose reaches the above range. [Examples]

[0110] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0111] In the examples and comparative examples, a phase-shift mask blank (halftone phase-shift mask blank) was manufactured by laminating a phase-shift film (halftone phase-shift film) made of a material containing silicon (Si) but not carbon (C) and a light-shielding film made of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C) onto a transparent substrate made of synthetic quartz glass measuring 152 mm square and approximately 6 mm thick.

[0112] [Examples 1-10] First, a silicon (Si) target was used as the target on a transparent substrate. The applied power to the target was adjusted, and sputtering was performed in an atmosphere using argon (Ar) gas and nitrogen (N2) gas as the sputtering gases. This formed a single-layer phase-shift film (65 nm thick) of silicon nitride (SiN) with a phase difference of 177 degrees and a transmittance of 6% (optical density (OD) of 1.22) relative to an ArF excimer laser (wavelength 193 nm). Table 1 shows the composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6. The composition of the phase-shift film was measured by X-ray photoelectron spectroscopy (the same method was used in the following examples). The zeta potential was measured using an electrophoretic photometer (the same method was used in the following examples).

[0113] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the fourth layer, third layer, second layer, and first layer, to form a light-shielding film consisting of the first, second, third, and fourth layers from the side away from the transparent substrate, with the first layer being chromium oxide nitride (CrON), the second layer being chromium carbide oxide nitride (CrONC), the third layer being chromium oxide nitride (CrON), and the fourth layer being chromium oxide nitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an 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 (the same method is used in the following examples). The sheet resistance was measured using the four-probe method (the same method is used in the following examples).

[0114] [Example 11] First, on a transparent substrate, a silicon (Si) target and a molybdenum (Mo) target were used as targets, and the applied power to the targets was adjusted. Additionally, argon (Ar) gas, oxygen (O2) gas, and nitrogen (N2) gas were used as sputtering gases. Sputtering was performed in these gas atmospheres to form a single-layer phase-shift film (69 nm thick) of silicon oxynitride (MoSiON) 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). Table 1 shows the composition of the phase-shift film and the zeta potentials at pH values ​​of 3, 4, 5, and 6.

[0115] Next, a light-shielding film similar to that in Example 1 was formed on the phase-shift film in the same manner as in Example 1 to obtain a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0116] [Example 12] First, a phase-shift film similar to that in Example 11 was formed on a transparent substrate using the same method as in Example 11. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 1.

[0117] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the fourth layer, third layer, second layer, and first layer, to form a light-shielding film consisting of the first, second, third, and fourth layers from the side away from the transparent substrate, with the first layer being chromium oxide (CrO), the second layer being chromium carbide oxynitride (CrONC), the third layer being chromium oxynitride (CrON), and the fourth layer being chromium oxynitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0118] [Example 13] First, a phase-shift film similar to that in Example 11 was formed on a transparent substrate using the same method as in Example 11. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 1.

[0119] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the fourth layer, third layer, second layer, and first layer, to form a light-shielding film consisting of the first, second, third, and fourth layers from the side away from the transparent substrate, with the first layer being chromium oxide nitride (CrON), the second layer being chromium oxide nitride (CrONC), the third layer being chromium nitride (CrN), and the fourth layer being chromium oxide nitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0120] [Example 14] First, a phase-shift film similar to that in Example 11 was formed on a transparent substrate using the same method as in Example 11. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 1.

[0121] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the fourth layer, third layer, second layer, and first layer, forming a light-shielding film consisting of the first, second, third, and fourth layers from the side away from the transparent substrate, with the first layer being chromium carbide oxynitride (CrONC), the second layer being chromium carbide oxynitride (CrONC), the third layer being chromium oxynitride (CrON), and the fourth layer being chromium oxynitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0122] [Example 15] First, a phase-shift film similar to that in Example 11 was formed on a transparent substrate using the same method as in Example 11. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 1.

[0123] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the fourth layer, third layer, second layer, and first layer, forming a light-shielding film consisting of the first, second, third, and fourth layers from the side away from the transparent substrate, with the first layer being chromium oxide nitride (CrON), the second layer being chromium carbide oxide nitride (CrONC), the third layer being chromium carbide oxide nitride (CrONC), and the fourth layer being chromium oxide nitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0124] [Example 16] First, a phase-shift film similar to that in Example 1 was formed on a transparent substrate using the same method as in Example 1. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 1.

[0125] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the 4th layer, 2nd layer, 3rd layer, and 1st layer, forming a light-shielding film consisting of the 1st layer, 3rd layer, 2nd layer, and 4th layer from the side away from the transparent substrate, with the 1st layer being chromium oxide nitride (CrON), the 3rd layer being chromium oxide nitride (CrON), the 2nd layer being chromium oxide nitride (CrONC), and the 4th layer being chromium oxide nitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0126] [Example 17] First, a phase-shift film similar to that in Example 11 was formed on a transparent substrate using the same method as in Example 11. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 1.

[0127] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the 4th layer, 2nd layer, 3rd layer, and 1st layer, forming a light-shielding film consisting of the 1st layer, 3rd layer, 2nd layer, and 4th layer from the side away from the transparent substrate, with the 1st layer being chromium oxide nitride (CrON), the 3rd layer being chromium oxide nitride (CrON), the 2nd layer being chromium oxide nitride (CrONC), and the 4th layer being chromium oxide nitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 1.

[0128] [Comparative Example 1] First, on a transparent substrate, a silicon (Si) target and a molybdenum (Mo) target were used as targets. The power applied to the targets was adjusted, and sputtering was performed in an atmosphere using argon (Ar) gas, oxygen (O2) gas, and nitrogen (N2) gas as sputtering gases. This formed a single-layer phase-shift film (75 nm thick) of silicon oxynitride (MoSiON) 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). The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 2.

[0129] Next, a chromium (Cr) target was used as the target on the phase-shift film. The power applied to the target was adjusted, and argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases. The ratio of the sputtering gases was adjusted, and sputtering was performed in these gas atmospheres to form a single-layer light-shielding film of chromium oxidiznitride (CrONC) to obtain a phase-shift mask blank. The composition and thickness of the light-shielding film, the optical density (OD) of the light-shielding film against an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0130] [Comparative Example 2] First, a phase-shift film similar to that in Comparative Example 1 was formed on a transparent substrate using the same method as in Comparative Example 1. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 2.

[0131] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the fourth layer, third layer, second layer, and first layer, to form a light-shielding film consisting of the first, second, third, and fourth layers from the side away from the transparent substrate, with the first layer being chromium oxide nitride (CrON), the second layer being chromium carbide oxide nitride (CrONC), the third layer being chromium oxide nitride (CrON), and the fourth layer being chromium carbide oxide nitride (CrONC), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0132] [Comparative Example 3] First, a phase-shift film similar to that in Example 1 was formed on a transparent substrate using the same method as in Example 1. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 2.

[0133] Next, a light-shielding film similar to that in Comparative Example 1 was formed on the phase-shift film using the same method as in Comparative Example 1 to obtain a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the optical density (OD) of the light-shielding film against an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0134] [Comparative Example 4] First, a phase-shift film similar to that in Comparative Example 1 was formed on a transparent substrate using the same method as in Comparative Example 1. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 2.

[0135] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the lower layer and then the upper layer, forming a light-shielding film consisting of two layers, an upper and a lower layer, from the side away from the transparent substrate. The upper layer was made of chromium carbide oxynitride (CrONC) and the lower layer was made of chromium oxynitride (CrON), and a phase-shift mask blank was obtained. Table 2 shows the composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) against an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film.

[0136] [Comparative Example 5] First, a phase-shift film similar to that in Comparative Example 1 was formed on a transparent substrate using the same method as in Comparative Example 1. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 2.

[0137] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of lower, middle, and upper layers to form a light-shielding film consisting of three layers, upper, middle, and lower, from the side away from the transparent substrate. The upper layer was made of chromium oxynitride (CrON), the middle layer of chromium carbide oxynitride (CrONC), and the lower layer of chromium oxynitride (CrON), and a phase-shift mask blank was obtained. Table 2 shows the composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film.

[0138] [Comparative Example 6] First, a phase-shift film similar to that in Example 1 was formed on a transparent substrate using the same method as in Example 1. The composition of the phase-shift film and the zeta potentials at pH 3, 4, 5, and 6 are shown in Table 2.

[0139] Next, a chromium (Cr) target was used as the target on the phase-shift film, and the power applied to the target was adjusted. Argon (Ar) gas, oxygen (O2) gas, nitrogen (N2) gas, and carbon dioxide (CO2) gas were used as sputtering gases, and the ratio of the sputtering gases was adjusted. In this gas atmosphere, sputtering was performed in the order of the fourth layer, third layer, second layer, and first layer, forming a light-shielding film consisting of the first, second, third, and fourth layers from the side away from the transparent substrate, with the first layer being chromium oxide nitride (CrON), the second layer being chromium carbide oxide nitride (CrONC), the third layer being chromium carbide oxide nitride (CrONC), and the fourth layer being chromium oxide nitride (CrON), thereby obtaining a phase-shift mask blank. The composition and thickness of each layer of the light-shielding film, the overall thickness of the light-shielding film, the optical density (OD) for an ArF excimer laser (wavelength 193 nm), and the sheet resistance of the light-shielding film are shown in Table 2.

[0140] [Table 1]

[0141] [Table 2]

[0142] Next, using the phase-shift mask blanks obtained in the examples and comparative examples, dry etching was performed using a chlorine (Cl) gas containing oxygen (O) under the following condition 1, and the clear time (the time until the light-shielding film disappears due to dry etching and the endpoint is detected) was measured. The clear time and the etching rate calculated from the thickness of the light-shielding film and the clear time are shown in Table 3.

[0143] <Condition 1: Dry etching using a chlorine (Cl)-based gas containing oxygen (O)> Equipment: ICP (Inductively Coupled Plasma) system Gas: Cl2 gas (150 sccm) + O2 gas (50 sccm) Gas pressure: 3.0 mTorr (0.40 Pa) ICP power: 350W

[0144] [Table 3]

[0145] In the light-shielding films of the examples, the fourth layer does not contain carbon (C), but the second layer does, and the oxygen (O) content of the first and fourth layers is relatively high. In particular, in Examples 7 and 10, the chromium (Cr) content of the second layer is relatively low, and the oxygen (O) content is relatively high. Therefore, as shown in Table 3, even though the light-shielding film has a third layer with a relatively high nitrogen (N) content, the etching time (clear time) of the entire light-shielding film is shorter than that of Comparative Example 1. Furthermore, the light-shielding films of the examples also ensure the necessary light-shielding properties (optical density (OD)) as a whole.

[0146] Next, a phase shift mask was manufactured using another phase shift mask blank obtained in the examples and comparative examples.

[0147] First, a positive-type chemically amplified electron beam resist was spin-coated onto a light-shielding film to form a first resist film with a thickness of 120 nm (Step (A)).

[0148] Next, using an electron beam lithography system, a dose of 35 μC / cm² was used. 2Next, a line-and-space pattern with a long side dimension of 100,000 nm, a short side line dimension of 200 nm, and a short side space dimension of 200 nm was drawn, totaling 100 million lines. In addition, a 10 mm x 10 mm space pattern was drawn to measure the phase difference and transmittance. Then, heat treatment (PEB: Post Exposure Bake) was performed at 110°C for 14 minutes using a heat treatment device. Next, development was performed for 80 seconds using paddle development to form the first resist pattern ((B) step).

[0149] Next, using the first resist pattern as an etching mask, a light-shielding film pattern was formed by dry etching using a chlorine (Cl)-based gas containing oxygen (O) under the following condition 2 ((C) step).

[0150] <Condition 2: Dry etching using a chlorine (Cl)-based gas containing oxygen (O)> Equipment: ICP (Inductively Coupled Plasma) system Gas: Cl2 gas (150 sccm) + O2 gas (50 sccm) Gas pressure: 3.0 mTorr (0.40 Pa) ICP power: 350W Over-etching time: 100% (Etching time: 200% of clear time)

[0151] Next, using the light-shielding film pattern as an etching mask, the phase-shift film was patterned by dry etching using a fluorine (F)-based gas under the following condition 3 to form a phase-shift film pattern (step (D)).

[0152] <Condition 3: Dry etching using fluorine (F) gas> Equipment: ICP (Inductively Coupled Plasma) system Gas: SF6 gas + He gas Gas pressure: 4.0 mTorr (0.53 Pa) ICP power: 400W

[0153] Next, the first resist pattern was removed by washing with sulfuric acid peroxide (a mixture of sulfuric acid and hydrogen peroxide in a 3:1 volume ratio) at 100°C for 6 minutes (step (E)).

[0154] Next, a laser resist was spin-coated onto the transparent substrate, which was exposed after the light-shielding film pattern and phase-shift film were removed, to form a second resist film with a thickness (thickness on the transparent substrate) of 465 nm (step (F)).

[0155] Next, using a laser lithography apparatus, an effective region including the circuit pattern of the phase-shift film was drawn so that a second resist film remained in the area located at the outer edge of the transparent substrate. Then, using a heat treatment apparatus, heat treatment (PEB: Post Exposure Bake) was performed at 110°C for 20 minutes. Next, development was performed by spray development for 200 seconds to form a second resist pattern in the outer edge located outside the region where the circuit pattern of the phase-shift film was formed (step (G)).

[0156] Next, using the second resist pattern as an etching mask, the light-shielding film pattern in the region where the circuit pattern of the phase-shift film is formed was removed by dry etching using a chlorine (Cl) gas containing oxygen (O) under the conditions described in (H) above.

[0157] Next, the second resist pattern was removed by washing with sulfuric acid peroxide (a mixture of sulfuric acid and hydrogen peroxide in a 3:1 volume ratio) at 100°C for 6 minutes (step (I)) to obtain a phase shift mask.

[0158] Next, using a phase difference and transmittance measuring device, the phase difference and transmittance were measured between the 10 mm × 10 mm space pattern formed on the obtained phase shift mask and the surrounding phase shift film pattern. The difference between the phase difference and transmittance of the phase shift film and the set values ​​(the difference between the set values ​​and the measured values ​​of phase difference and transmittance (difference before and after manufacturing)) was determined. The results are shown in Table 4.

[0159] Next, the phase shift mask was washed five times with sulfuric acid peroxide (a mixture of sulfuric acid and hydrogen peroxide in a 3:1 volume ratio) at 100°C for 6 minutes. Then, using a phase difference and transmittance measuring device, the phase difference and transmittance were measured between a 10 mm × 10 mm space pattern formed on the obtained phase shift mask and the surrounding phase shift film pattern. The difference between the phase difference and transmittance of the phase shift film pattern before and after washing (difference in phase difference and transmittance before and after washing) was determined. The results are shown in Table 4.

[0160] [Table 4]

[0161] Compared to a phase-shift film pattern in which the carbon (C)-containing layer of the light-shielding film was in contact, it was confirmed that the phase difference and transmittance changes of the phase-shift film (phase-shift film pattern) in contact with sulfuric acid peroxide were suppressed in a phase-shift film pattern in which the carbon (C)-free layer of the light-shielding film was in contact.

[0162] Next, the phase shift mask, on which the phase difference and transmittance changes were measured, was placed in the exposure apparatus. An ArF excimer laser (wavelength 193 nm) was irradiated onto the line and space pattern formed on the phase shift mask, with a long side dimension of 100,000 nm, a short side line dimension of 200 nm, and a short side space dimension of 200 nm, under condition 4 below, until a cumulative irradiation dose of 10 kJ / cm² was detected. 2 , 20 kJ / cm² 2 30 kJ / cm² 2 40 kJ / cm² 2 50 kJ / cm² 2 Each time, the sample was removed from the exposure apparatus, and the presence or absence of defects in the line-and-space pattern was evaluated using a mask pattern inspection device. Furthermore, the composition of the defects was analyzed using TEM / EDX to identify ammonium sulfate ((NH4)2SO4) haze and chromium oxide (CrO) haze. The results are shown in Table 5.

[0163] <Condition 4: Irradiation conditions for ArF excimer laser (wavelength 193nm)> Laser intensity: 2.5 mJ / pulse / cm 2 Laser frequency: 1600Hz Laser irradiation area: 5mm x 5mm Temperature inside the exposure chamber (atmosphere when the phase shift mask is installed): 23℃ Humidity in the exposure chamber (atmosphere when the phase shift mask is installed): 43%

[0164] [Table 5]

[0165] Compared to phase-shift film patterns in which a carbon (C)-containing layer of the light-shielding film was in contact, it was confirmed that the generation of chromium oxide haze was suppressed in phase-shift film patterns in which a carbon (C)-containing layer of the light-shielding film was in contact, and that the generation of chromium oxide haze was also suppressed even when the phase-shift film pattern contained molybdenum (Mo). Furthermore, in phase-shift film patterns containing molybdenum (Mo) and in contact with a carbon (C)-containing layer of the light-shielding film, the generation of chromium oxide haze was confirmed. In addition, compared to phase-shift films (phase-shift film patterns) whose zeta potential did not meet the specified range (zeta potential of -15mV to +15mV for pH 3 to 4 and -60mV to +10mV for pH 5 to 6), it was confirmed that the generation of ammonium sulfate ((NH4)2SO4) haze was suppressed in phase-shift films (phase-shift film patterns) whose zeta potential met the specified range. [Explanation of symbols]

[0166] 1 Transparent substrate 2 Phase-shift film 2a Phase-shifted film pattern 3. Light-shielding film 3a Light-shielding film pattern 30 Laminated structure 31 1st layer 32 2nd layer 33 3rd layer 34 4th layer 4. Effective area 101, 103 Phase Shift Mask Blank 102,104 Phase Shift Mask

Claims

1. Transparent substrate and A phase-shift film is provided on the transparent substrate and is formed of a material containing silicon (Si) but not carbon (C), A light-shielding film is provided on the side of the phase-shift film that is separated from the transparent substrate, and is made of a material containing chromium (Cr), oxygen (O), nitrogen (N), and carbon (C). A phase shift mask blank comprising, The above light-shielding film has a laminated structure consisting of four layers, a first layer, a second layer, a third layer, and a fourth layer, arranged in order from the side separated from the transparent substrate, or a first layer, a third layer, a second layer, and a fourth layer. In the above laminated structure, the first layer is the layer furthest from the transparent substrate, and the fourth layer is the layer in contact with the phase-shift film. The above-mentioned first layer contains chromium (Cr) and oxygen (O), with a chromium (Cr) content of 28 atomic% to 40 atomic%, an oxygen (O) content of 47 atomic% to 60 atomic%, and a thickness of 1 nm to 4 nm. The above-mentioned second layer contains chromium (Cr), oxygen (O), nitrogen (N), and carbon (C), with a chromium (Cr) content of 30 atomic% to 45 atomic%, an oxygen (O) content of 28 atomic% to 40 atomic%, a nitrogen (N) content of 12 atomic% to 24 atomic%, a carbon (C) content of 5 atomic% to 15 atomic%, and a thickness of 18 nm to 24 nm. The above third layer contains chromium (Cr) and nitrogen (N), with a chromium (Cr) content of 50 atomic% to 60 atomic%, a nitrogen (N) content of 20 atomic% to 40 atomic%, and a thickness of 1 nm to 6 nm. The above fourth layer contains chromium (Cr), oxygen (O), and nitrogen (N), but does not contain carbon (C), with a chromium (Cr) content of 35 atomic% to 44 atomic%, an oxygen (O) content of 42 atomic% to 54 atomic%, a nitrogen (N) content of 2 atomic% to 20 atomic%, and a thickness of 18 nm to 36 nm. A phase-shift mask blank characterized by the following features.

2. The phase-shift mask blank according to claim 1, characterized in that the zeta potential of the phase-shift membrane described above is -15 mV to +15 mV when the pH is 3 or higher and 4 or lower, and the zeta potential of the phase-shift membrane is -60 mV to +10 mV when the pH is 5 or higher and 6 or lower.

3. The above first layer contains nitrogen (N), and the nitrogen (N) content is between 5 atomic percent and 25 atomic percent. The above third layer contains oxygen (O), and the oxygen (O) content is between 6 atomic percent and 30 atomic percent. The phase shift mask blank according to feature 1.

4. The phase shift mask blank according to claim 1, characterized in that the material used to form the phase shift film contains nitrogen (N).

5. The phase shift mask blank according to claim 1, characterized in that the material used to form the phase shift film does not contain a transition metal.

6. The phase shift mask blank according to claim 1, characterized in that the total sheet resistance of the first, second, third, and fourth layers of the light-shielding film is 350 kΩ / □ or less.

7. The phase difference of the above-mentioned phase-shift film with respect to exposure light from an ArF excimer laser (wavelength 193 nm) is 175 degrees or more and 185 degrees or less, and the transmittance is 6% or more and 30% or less, and The phase-shift mask blank according to claim 1, characterized in that the thickness of the phase-shift film is 60 nm or more and 85 nm or less.

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

9. The phase shift mask blank according to claim 8, characterized in that the thickness of the light-shielding film is 48 nm or more and 54 nm or less.

10. A method for manufacturing a phase shift mask having the circuit pattern of the phase shift film from a phase shift mask blank according to any one of claims 1 to 9, (A) A step of forming a first resist film on the above light-shielding film, (B) A step of patterning the first resist film to form a first resist pattern, (C) A step of forming a light-shielding film pattern by patterning the light-shielding film using the first resist pattern described above as an etching mask, by dry etching with a chlorine (Cl)-based gas containing oxygen (O), (D) A step of forming a phase-shift film pattern by patterning the phase-shift film using the above light-shielding film pattern as an etching mask and dry etching with a fluorine (F)-based gas, (E) A step of removing the first resist pattern described above, (F) A step of forming a second resist film on the above light-shielding film pattern, (G) A step of patterning the second resist film to form a second resist pattern on the outer peripheral edge located outside the region where the circuit pattern of the phase shift film is formed, (H) Using the second resist pattern described above as an etching mask, the light-shielding film pattern in the region where the circuit pattern of the phase-shift film is formed is removed by dry etching using a chlorine (Cl) gas containing oxygen (O), (I) A step of removing the second resist pattern described above A method for manufacturing a phase shift mask, characterized by including the following:

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