Mask blank, phase shift mask, method for manufacturing phase shift mask, and method for manufacturing semiconductor device

Abstract

Provided is a mask blank that enables, without complicating the mask-manufacturing process, creation of patterns of differing transmittance with desired accuracy, and achievement of a desired phase-shift function in each pattern.　This mask blank is characterized in that: a transmittance-adjusting film is provided atop a phase-shift film; the phase-shift film produces, in exposure light from an ArF excimer laser transmitting through the phase-shift film, a phase difference of 150-210 degrees from the exposure light having passed through air for a distance equivalent to the thickness of the phase shift film; and the relationships of the following formulas (1) and (2) are satisfied where the refractive index at the wavelength of the exposure light through the transmittance-adjusting film is nU, the extinction coefficient at the wavelength of the exposure light is kU, and the thickness is dU[nm]. Formula (1) dU ≤ −17.63 × nU 3 + 142.0 × nU 2 −364.9 × nU + 315.8 Formula (2) dU ≥ −2.805 × kU 3 + 19.48 × kU 2 −43.58 × kU + 38.11

Description

[Technical field]

[0001] The present invention relates to a mask blank, a phase shift mask, a method for manufacturing a phase shift mask, and a method for manufacturing a semiconductor device. [Background technology]

[0002] In general, in the manufacturing process of semiconductor devices, fine patterns are formed using a photolithography method. In addition, many substrates called transfer masks are usually used to form these fine patterns. In order to miniaturize the patterns of semiconductor devices, it is necessary to shorten the wavelength of the exposure light source used in photolithography in addition to miniaturizing the mask pattern formed on the transfer mask. In recent years, the wavelength of the exposure light source used in semiconductor device manufacturing has been shortened from KrF excimer laser (wavelength 248 nm) to ArF excimer laser (wavelength 193 nm).

[0003] As a type of transfer mask, in addition to the conventional binary mask with a light-shielding pattern made of a chromium-based material on a light-transmitting substrate, a half-tone phase-shift mask is known. Molybdenum silicide (MoSi)-based materials are widely used for the phase-shift film of the half-tone phase-shift mask.

[0004] Patent Document 1 discloses a phase shift mask in which an etching stop film 3 and a phase shift layer 4 forming a predetermined pattern are sequentially formed on a transparent substrate 2, a light-shielding film pattern 5 made of chromium is formed on the phase shift layer 4 formed in region A, and a semi-transparent film pattern 6 made of molybdenum silicide is formed on the phase shift layer 4 formed in region B, and in which a Levenson type phase shift mask and a halftone type phase shift mask are formed on the same substrate. Patent Document 2 discloses a phase shift mask including halftone film 12 provided on a portion of light-transmitting substrate 11 where a light-shielding pattern is to be formed and a portion where a semi-light-shielding pattern is to be formed, and light-shielding film 13 provided on halftone film 12 in the portion of halftone film 12 where the light-shielding pattern is to be formed. The semi-light-shielding pattern includes a first semi-light-shielding pattern made of halftone film 12 and a second semi-light-shielding pattern made of a halftone film having a smaller dimension than the first semi-light-shielding pattern, and an element that adjusts the light transmittance of light transmission path 32 is included in light transmission path 32 in the region including this second semi-light-shielding pattern. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-123961 [Patent Document 2] JP 2007-279441 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the types of patterns required have become more diverse and complex, and even in the transfer patterns formed on the halftone phase shift mask, finer patterns and relatively sparse patterns may coexist. The transmittance suitable for obtaining a good phase shift effect may differ depending on the type of pattern. That is, depending on the type and pitch of the pattern to be transferred, it may be preferable to increase the transmittance in some cases, and to suppress the transmittance in other cases. And, how to set the region having a relatively high transmittance and the region having a relatively low transmittance in the transfer region differs depending on the semiconductor device to be transferred, so there is a demand for a mask blank with a high degree of design freedom that can set a region having a desired transmittance corresponding to the type of pattern to be formed on the transfer target.

[0007] The phase shift mask described in Patent Document 1 has a light-shielding film pattern formed in region A and a semi-light-transmitting film pattern 5 formed in the other region B, and this phase shift mask itself is useful. However, this phase shift mask has a Levenson type phase shift pattern provided in region A and a halftone type phase shift pattern provided in region B, and thus patterns that produce different phase shift effects are mixed in plan view. This halftone type phase shift mask does not meet the demand for providing halftone type phase shift patterns with different transmittances.

[0008] Moreover, the phase shift mask described in Patent Document 2 performs a process of implanting Ga ions into a halftone mask blank to reduce the light transmittance of the implanted region. This process is not performed when making a normal mask, and requires an ion implantation mechanism in the mask manufacturing device, which complicates the mask manufacturing process. Moreover, since the ions implanted into the mask blank may diffuse from the desired region, it is difficult to meet the requirements for manufacturing fine patterns.

[0009] Therefore, the present invention has been made to solve the problems of the prior art, and aims to provide a mask blank having a phase shift film on a light-transmitting substrate, which can create patterns with different transmittances with a desired accuracy without complicating the process (mask manufacturing process) for manufacturing a phase shift mask from the mask blank, and which has a phase shift film that can obtain a desired phase shift function for each pattern. Another aim is to provide a phase shift mask manufactured using this mask blank, and a manufacturing method for a phase shift mask. And, another aim of the present invention is to provide a manufacturing method for a semiconductor device using such a phase shift mask. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention has the following configuration. (Configuration 1) A mask blank having a phase shift film on a light-transmitting substrate, a transmittance adjusting film on the phase shift film, the phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between ArF excimer laser exposure light that has passed through the phase shift film and the exposure light that has passed through air a distance equal to the thickness of the phase shift film, The refractive index of the transmittance adjusting film at the wavelength of the exposure light is n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d U A mask blank characterized in that, when expressed as [nm], the relationship of both the following formula (1) and formula (2) is satisfied. Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0011] (Configuration 2) The refractive index n of the transmittance adjusting film U The mask blank according to configuration 1, wherein the ratio of the first peak to the second peak is 1.2 or more. (Configuration 3) The extinction coefficient k of the transmittance adjusting film U 3. The mask blank according to claim 1 or 2, wherein:

[0012] (Configuration 4) 4. The mask blank according to any one of configurations 1 to 3, wherein the phase shift film transmits the exposure light with a transmittance of 12% or more. (Configuration 5) The extinction coefficient k of the transmittance adjusting filmU and the thickness d U 5. The mask blank according to any one of configurations 1 to 4, wherein [nm] satisfies the relationship of the following formula (3): Formula (3) d U ≦8.646×k U 2 -38.42×k U +61.89

[0013] (Configuration 6) 6. The mask blank according to any one of configurations 1 to 5, wherein the transmittance adjusting film contains silicon and nitrogen. (Configuration 7) 7. The mask blank according to any one of configurations 1 to 6, further comprising an intermediate film containing silicon and oxygen between the phase shift film and the transmittance adjustment film.

[0014] (Configuration 8) 7. The mask blank according to any one of configurations 1 to 6, wherein the phase shift film has a top layer containing silicon and oxygen on the surface side opposite to the light-transmitting substrate side. (Configuration 9) 9. The mask blank according to any one of configurations 1 to 8, further comprising a light-shielding film on the transmittance adjusting film.

[0015] (Configuration 10) A phase shift mask comprising a phase shift film having a first pattern on a light-transmitting substrate, a transmittance adjusting film having a second pattern on the phase shift film, the phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between ArF excimer laser exposure light that has passed through the phase shift film and the exposure light that has passed through air a distance equal to the thickness of the phase shift film, The refractive index of the transmittance adjusting film at the wavelength of the exposure light is n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d UA phase shift mask characterized in that, when expressed in nm, the relationship of the following formulas (1) and (2) is satisfied. Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11 (Configuration 11) The refractive index n of the transmittance adjusting film U 11. The phase shift mask according to structure 10, wherein is 1.2 or more.

[0016] (Configuration 12) The extinction coefficient k of the transmittance adjusting film U 12. The phase shift mask according to structure 10 or 11, wherein: (Configuration 13) 13. The phase shift mask of any one of Structures 10 to 12, wherein the phase shift film transmits the exposure light with a transmittance of 12% or more.

[0017] (Configuration 14) The extinction coefficient k of the transmittance adjusting film U and the thickness d U 14. The phase shift mask according to any one of configurations 10 to 13, wherein [nm] satisfies the following formula (3): Formula (3) d U ≦8.646×k U 2 -38.42×k U +61.89 (Configuration 15) 15. The phase shift mask according to any one of configurations 10 to 14, wherein the transmittance adjustment film contains silicon and nitrogen.

[0018] (Configuration 16) 16. A phase shift mask according to any one of structures 10 to 15, further comprising an intermediate film having the second pattern between the phase shift film and the transmittance adjustment film, the intermediate film containing silicon and oxygen. (Configuration 17) 16. A phase shift mask according to any one of structures 10 to 15, wherein the phase shift film has a top layer containing silicon and oxygen on the surface side opposite the light-transmitting substrate.

[0019] (Configuration 18) 18. The phase shift mask of any one of configurations 10 to 17, further comprising a light-shielding film having a third pattern on the transmittance adjusting film. (Configuration 19) A method for producing a phase shift mask using the mask blank according to configuration 9, comprising the steps of: forming a first pattern in the light-shielding film by dry etching; forming a first pattern in each of the transmittance adjustment film and the phase shift film by dry etching using the light-shielding film having the first pattern as a mask; forming a second pattern in the light-shielding film by dry etching; forming a second pattern in the transmittance adjusting film by dry etching using the light-shielding film having the second pattern as a mask; forming a third pattern in the light-shielding film by dry etching; 2. A method for manufacturing a phase shift mask comprising: (Configuration 20) 19. A method for manufacturing a semiconductor device, comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask according to claim 18. Effect of the Invention

[0020] The mask blank of the present invention can provide a mask blank that can create patterns with different transmittances with the desired precision without complicating the mask manufacturing process, and can provide a desired phase shift function for each pattern. [Brief description of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view showing a configuration of a mask blank in a first embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view showing a configuration of a phase shift mask in a first embodiment of the present invention. [Diagram 3] 1A to 1C are schematic cross-sectional views showing main steps of a manufacturing process for a phase shift mask according to a first embodiment of the present invention. [Figure 4] 1A to 1C are schematic cross-sectional views showing main steps of a manufacturing process for a phase shift mask according to a first embodiment of the present invention. [Diagram 5] FIG. 4 is a cross-sectional view showing a configuration of a mask blank in a second embodiment of the present invention. [Figure 6] FIG. 11 is a cross-sectional view showing a configuration of a phase shift mask according to a second embodiment of the present invention. [Figure 7] 5A to 5C are schematic cross-sectional views showing main steps of a manufacturing process for a phase shift mask according to a second embodiment of the present invention. [Figure 8] 5A to 5C are schematic cross-sectional views showing main steps of a manufacturing process for a phase shift mask according to a second embodiment of the present invention. [Figure 9] FIG. 13 is a diagram showing the relationship between the maximum film thickness of the transmittance adjusting film and the refractive index n for satisfying that the increase in phase difference is equal to or less than a predetermined value, which is derived from the result of optical simulation A1. [Figure 10] FIG. 13 is a diagram showing the relationship between the maximum film thickness of the transmittance adjustment film and the refractive index n for satisfying that the increase in phase difference is equal to or less than a predetermined value, derived from the results of optical simulations A1 and B1. [Figure 11]FIG. 13 is a diagram showing the relationship between the minimum film thickness of the transmittance adjusting film and the extinction coefficient k for satisfying that the transmittance ratio is equal to or less than a predetermined value, derived from the results of optical simulations A2 and B2. [Figure 12] FIG. 13 is a diagram showing the relationship between the maximum film thickness of the transmittance adjustment film and the extinction coefficient k, derived from the results of optical simulations A3 and B3, for satisfying that the transmittance of exposure light transmitted through a laminated structure of a phase shift film and a transmittance adjustment film is equal to or greater than a predetermined value. [Figure 13] FIG. 11 is a cross-sectional view showing a configuration of a mask blank in a third embodiment of the present invention. [Figure 14] FIG. 11 is a cross-sectional view showing a configuration of a phase shift mask according to a third embodiment of the present invention. [Figure 15] 11A to 11C are schematic cross-sectional views showing main steps of a manufacturing process for a phase shift mask according to a third embodiment of the present invention. [Figure 16] 11A to 11C are schematic cross-sectional views showing main steps of a manufacturing process for a phase shift mask according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present inventors have conducted extensive research into a phase shift film that can produce patterns with different transmittances with a desired accuracy without complicating the mask manufacturing process, and can provide a desired phase shift function for each pattern. First, in order to create a pattern with different transmittance, a configuration having a transmittance adjustment film on a phase shift film was conceived. The phase shift film has a function of generating a phase difference of 150 degrees or more and 210 degrees or less between the exposure light of the ArF excimer laser that has passed through the phase shift film and the exposure light that has passed through the air a distance equal to the thickness of the phase shift film (hereinafter, appropriately referred to as "desired phase shift function"). In this way, in the portion where the transmittance adjustment film on the phase shift mask has been removed, the exposure light of the ArF excimer laser (hereinafter, appropriately referred to as "exposure light") passes through the phase shift film with a predetermined transmittance, and the above-mentioned desired phase shift function can be obtained. Furthermore, further investigation was conducted into the configuration of the transmittance adjustment film that would provide the desired phase shift function for the exposure light that had passed through the phase shift film and the transmittance adjustment film, while also providing a transmittance that was significantly different from the transmittance of the exposure light that had passed through the phase shift film.

[0023] First, regarding the phase shift function, the inventors have studied the conditions for satisfying that the increase in the phase difference between the exposure light transmitted through the phase shift film and the laminated structure of the phase shift film and the transmittance adjustment film is 20 degrees or less. In this study, the inventors have focused on the relationship between the maximum film thickness of the transmittance adjustment film and the refractive index n, and performed optical simulation A1 for the phase shift film and the transmittance adjustment film. In optical simulation A1, the maximum film thickness of the transmittance adjustment film was calculated to satisfy that the increase in the phase difference is 20 degrees or less while changing the film thickness of the transmittance adjustment film in the range of refractive index n from 1.2 to 2.0. Here, the film thickness of the phase shift film is 60.4 nm, the refractive index n is 2.61, and the extinction coefficient k is 0.36. Note that the above refractive index n and extinction coefficient k are for the wavelength of ArF excimer laser light (wavelength 193 nm), and the same applies hereinafter unless otherwise specified.

[0024] In addition, in optical simulation A1, an intermediate film was set between the phase shift film and the transmittance adjustment film. This intermediate film was provided on the assumption that it would prevent the phase shift film from being etched when the transmittance adjustment film was patterned by dry etching. The intermediate film had a thickness of 3 nm, a refractive index n of 1.56, and an extinction coefficient k of 0.00. Because the intermediate film has these optical properties, its effect on the results of optical simulation A1 is minor.

[0025] Based on the results of this optical simulation A1, the relationship between the refractive index n and the maximum film thickness of the transmittance adjustment film was organized. Figure 9 is a diagram showing the relationship between the maximum film thickness and the refractive index n of the transmittance adjustment film, derived from the results of optical simulation A1, for satisfying that the increase in the phase difference of the exposure light transmitted through the phase shift film and the laminated structure of the phase shift film and the transmittance adjustment film is 20 degrees or less. Curves A11, A12, and A13 in Figure 9 respectively show the maximum film thicknesses of the transmittance adjustment film for satisfying that the increase in the phase difference is 20 degrees or less, 15 degrees or less, and 10 degrees or less.

[0026] The relational expression (the mathematical expression of the curve A11) of the maximum film thickness of the transmittance adjusting film for satisfying that the increase in the retardation is 20 degrees or less, as shown in FIG. d Umax =-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 9, the curves A12 and A13, which satisfy that the increase in the phase difference is 15 degrees or less and 10 degrees or less, are located below the curve A11. The relational expression (the mathematical expression of the curve A12) of the maximum film thickness of the transmittance adjusting film, which satisfies that the increase in the phase difference is 15 degrees or less, is as follows: d Umax =-70.62×n U 3 +406.5×n U 2 -795.7×n U+540.1 Furthermore, the relational expression (the mathematical expression of curve A13) of the maximum film thickness of the transmittance adjusting film for satisfying that the increase in the retardation is 10 degrees or less is as follows: d Umax = 201.1 × n U 4 -1407×n U 3 +3700×n U 2 -4356×n U +1956

[0027] From these results, the thickness of the transmittance control film d U [nm] and refractive index n U But, Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 It has been found that when the above condition is satisfied, the increase in phase difference between the exposure light transmitted through the phase shift film and the laminated structure of the phase shift film and the transmittance adjustment film is 20 degrees or less compared to the exposure light transmitted through the phase shift film. In addition, the thickness of the transmittance adjusting film d U [nm] and refractive index n U But, Formula (1-A12) d U ≦-70.62×n U 3 +406.5×n U 2 -795.7×n U +540.1 It has been found that when the above condition is satisfied, the increase in phase difference between the exposure light transmitted through the phase shift film and the laminated structure of the phase shift film and the transmittance adjustment film is 15 degrees or less compared to the exposure light transmitted through the phase shift film. Furthermore, the thickness of the transmittance adjusting film d U [nm] and refractive index n U But, Formula (1-A13) d U ≦201.1×n U 4 -1407×nU 3 +3700×n U 2 -4356×n U +1956 It has been found that when the above condition is satisfied, the increase in phase difference between the exposure light transmitted through the phase shift film and the laminated structure of the phase shift film and the transmittance adjustment film is 10 degrees or less compared to the exposure light transmitted through the phase shift film.

[0028] Furthermore, the inventors performed a similar optical simulation B1 by changing the conditions of the phase shift film. The phase shift film had a structure in which a first layer, a second layer, and a third layer were laminated from the light-transmitting substrate side. The first layer had a film thickness of 41 nm, a refractive index n of 2.61, and an extinction coefficient k of 0.36. The second layer had a film thickness of 24 nm, a refractive index n of 2.18, and an extinction coefficient k of 0.12. The third layer had a film thickness of 4 nm, a refractive index n of 1.56, and an extinction coefficient k of 0.00. In the optical simulation B, since the third layer can also function as the above-mentioned intermediate film, no intermediate film was provided between the phase shift film and the transmittance adjustment film. Based on the results of the optical simulation B1, the relationship between the refractive index n of the transmittance adjustment film and the maximum film thickness was organized.

[0029] Fig. 10 is a graph comparing the results of optical simulation A1 and optical simulation B1 regarding the relationship between the maximum film thickness of the transmittance adjustment film and the refractive index n. Curves A11, A12, and A13 shown in Fig. 10 are the results of optical simulation A1, and are the same as those shown in Fig. 9. Curves B11, B12, and B13 shown in Fig. 10 are the results of optical simulation B1, and respectively indicate the maximum film thickness of the transmittance adjustment film for satisfying that the increase in the phase difference is 14 degrees or less, 11 degrees or less, and 6 degrees or less, respectively.

[0030] In FIG. 10, the curve A11 is below the curve B11 (the curve with the threshold value of the increase in the phase difference of 14 degrees). This indicates that the transmittance adjustment film satisfying the relationship of the formula (1) derived based on the curve A11 will increase the phase difference by 14 degrees or less even when it is provided on the phase shift film used in the optical simulation B1. Similarly, the curve A12 is below the curve B12. This indicates that the transmittance adjustment film satisfying the relationship of the formula (1-A12) derived based on the curve A12 will increase the phase difference by 11 degrees or less even when it is provided on the phase shift film used in the optical simulation B1. Similarly, the curve A13 is below the curve B13. This indicates that the transmittance adjustment film satisfying the relationship of the formula (1-A13) derived based on the curve A13 will increase the phase difference by 6 degrees or less even when it is provided on the phase shift film used in the optical simulation B1. These results mean that if a transmittance adjustment film satisfies the relationship of formula (1), the increase in phase difference described above will be 20 degrees or less, regardless of the optical characteristics of the phase shift film provided underneath it.

[0031] On the other hand, the present inventors have studied conditions for satisfying that the ratio of the transmittance Ts of the exposure light transmitted through the laminated structure of the phase shift film and the transmittance adjustment film to the transmittance Tp of the exposure light transmitted through the phase shift film (i.e., Ts / Tp. Hereinafter, this may be simply referred to as the transmittance ratio) is 0.5 or less, as a transmittance that is significantly different from the transmittance of the exposure light transmitted through the phase shift film. In this study, the present inventors focused on the relationship between the minimum film thickness of the transmittance adjustment film and the extinction coefficient k, and performed optical simulations A2 and B2 for the phase shift film and the transmittance adjustment film, respectively. In the optical simulations A2 and B2, the minimum film thickness of the transmittance adjustment film was calculated to satisfy the transmittance ratio of 0.5 or less while changing the film thickness of the transmittance adjustment film within the range of the extinction coefficient k from 1.5 to 2.0. Note that, regarding the phase shift film, the same one as in the optical simulation A1 was used in the optical simulation A2, and the same one as in the optical simulation B1 was used in the optical simulation B2.

[0032] Then, based on the results of the simulations A2 and B2, the relationship between the extinction coefficient k of the transmittance adjustment film and the minimum film thickness was organized. FIG. 11 is a diagram comparing the results of the optical simulations A2 and B2 regarding the relationship between the minimum film thickness of the transmittance adjustment film and the extinction coefficient k. The curves A21 and A22 shown in FIG. 11 are the results of the optical simulation A2, and indicate the minimum film thickness of the transmittance adjustment film to satisfy the transmittance ratio of 0.50 or less and 0.45 or less, respectively. The curves B21 and B22 are the results of the optical simulation B2, and indicate the minimum film thickness of the transmittance adjustment film to satisfy the transmittance ratio of 0.50 or less and 0.43 or less, respectively.

[0033] The relational expression (the mathematical expression of curve A21) of the minimum film thickness of the transmittance adjusting film for satisfying the transmittance ratio of 0.5 or less shown in FIG. 11 is as follows: d Umin =-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11 11, the curve A22, which satisfies that the transmittance ratio is 0.45 or less, is located above the curve A21. The relational expression (the mathematical expression of the curve A22) of the minimum film thickness of the transmittance adjusting film, which satisfies that the transmittance ratio is 0.45 or less, is as follows: d Umin =8.592×k U 3 -38.60×k U 2 +54.28×k U -15.36

[0034] From these results, the thickness of the transmittance control film d U [nm] and the extinction coefficient k U But, Formula (2) d U ≧-2.805×k U 3 +19.48×k U2 -43.58×k U +38.11 It has been found that when the above requirement is satisfied, the ratio of the transmittance of the exposure light transmitted through the laminated structure of the phase shift film and the transmittance adjusting film to the transmittance of the exposure light transmitted through the phase shift film is 0.5 or less. In addition, the thickness of the transmittance adjusting film d U [nm] and the extinction coefficient k U But, Formula (2-A22) d U ≧8.592×k U 3 -38.60×k U 2 +54.28×k U -15.36 It has been found that when the above requirement is satisfied, the ratio of the transmittance of the exposure light transmitted through the laminated structure of the phase shift film and the transmittance adjusting film to the transmittance of the exposure light transmitted through the phase shift film is 0.45 or less.

[0035] In FIG. 11, the curve A21 is above the curve B21 (the curve with the threshold value of the transmittance ratio being 0.50). This indicates that the transmittance adjustment film that satisfies the relationship of the formula (2) derived based on the curve A21 has a transmittance ratio of 0.50 or less even when it is provided on the phase shift film used in the optical simulation B2. Similarly, the curve A22 is above the curve B22 (the curve with the threshold value of the transmittance ratio being 0.43). This indicates that the transmittance adjustment film that satisfies the relationship of the formula (2-A22) derived based on the curve A22 has a transmittance ratio of 0.45 or less even when it is provided on the phase shift film used in the optical simulation B2. These results mean that if the transmittance adjustment film satisfies the relationship of the formula (2), the transmittance ratio described above will be 0.50 or less, regardless of the optical properties of the phase shift film provided below it.

[0036] In this way, the present inventors have found that if the transmittance adjusting film satisfies the relationship of formula (1) and formula (2), the increase in the phase difference described above is 20 degrees or less, and the transmittance ratio described above is 0.50 or less. The present invention has been made as a result of the above-mentioned intensive investigations.

[0037] <First embodiment> [Mask blanks and their manufacturing] Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing the configuration of a mask blank 10 according to a first embodiment of the present invention. The mask blank 10 of the present invention shown in Fig. 1 has a structure in which a phase shift film 2, an intermediate film 3, a transmittance adjusting film 4, a light-shielding film 5, a hard mask film 6 and a resist film 7 are laminated in this order on a light-transmitting substrate 1.

[0038] The light-transmitting substrate 1 can be formed of synthetic quartz glass, as well as quartz glass, aluminosilicate glass, soda-lime glass, low-thermal expansion glass (SiO2-TiO2 glass, etc.). Among these, synthetic quartz glass has high transmittance to ArF excimer laser light and is particularly preferable as a material for forming the light-transmitting substrate 1 of the mask blank. The refractive index n of the material for forming the light-transmitting substrate 1 at the wavelength of the ArF exposure light (approximately 193 nm) is preferably 1.5 or more and 1.6 or less, more preferably 1.52 or more and 1.59 or less, and even more preferably 1.54 or more and 1.58 or less.

[0039] In order to obtain an appropriate phase shift effect, the phase shift film 2 is preferably adjusted so that the phase difference between the ArF exposure light passing through it and light passing through air a distance equal to the thickness of the phase shift film 2 is in the range of 150 degrees or more and 210 degrees or less. The phase difference in the phase shift film 2 is preferably 155 degrees or more, and more preferably 160 degrees or more. On the other hand, the phase difference in the phase shift film 2 is preferably 195 degrees or less, and more preferably 190 degrees or less.

[0040] The phase shift film 2 preferably transmits the exposure light with a transmittance of 12% or more. In recent years, NTD (Negative Tone Development) has come to be used as an exposure and development process for a resist film on a semiconductor substrate (wafer), and a bright field mask (a transfer mask with a high pattern aperture ratio) is often used therein. In a bright field phase shift mask, the transmittance of the phase shift film for the exposure light is set to 12% or more, thereby improving the balance between the zeroth order light and the first order light transmitted through the light transmitting portion. When this balance is improved, the effect of the exposure light transmitted through the phase shift film interfering with the zeroth order light and attenuating the light intensity becomes greater, thereby improving the pattern resolution on the resist film. In order to further enhance the pattern edge emphasis effect of the transferred image (projected optical image) due to the phase shift effect, the phase shift film 2 more preferably transmits with a transmittance of 19% or more, and more preferably transmits with a transmittance of 28% or more. On the other hand, the transmittance of the phase shift film 2 for the ArF exposure light is preferably 50% or less, and more preferably 40% or less. If the transmittance of the phase shift film 2 to the ArF exposure light exceeds 50%, the effect of the side lobe becomes too strong, which is undesirable.

[0041] The thickness of the phase shift film 2 is preferably 90 nm or less, and more preferably 80 nm or less, while the thickness of the phase shift film 2 is preferably 40 nm or more, and more preferably 50 nm or more.

[0042] In order to satisfy the above-mentioned conditions regarding the optical properties and the film thickness of the phase shift film 2, the refractive index n of the phase shift film is preferably 2.0 or more, and more preferably 2.1 or more. The refractive index n of the phase shift film 2 is preferably 3.0 or less, and more preferably 2.9 or less. The extinction coefficient k of the phase shift film 2 is preferably 0.9 or less, and more preferably 0.6 or less. The extinction coefficient k of the phase shift film 2 is preferably 0.1 or more.

[0043] The refractive index n and extinction coefficient k of a thin film including the phase shift film 2 are not determined only by the composition of the thin film. The film density and crystalline state of the thin film are also factors that affect the refractive index n and extinction coefficient k. For this reason, the conditions for forming a thin film by reactive sputtering are adjusted so that the thin film has the desired refractive index n and extinction coefficient k. In order to set the refractive index n and extinction coefficient k of the thin film to the above range, it is not limited to only adjusting the ratio of the mixed gas of noble gas and reactive gas (oxygen gas, nitrogen gas, etc.) when forming the thin film by reactive sputtering. There are many factors, such as the pressure in the film formation chamber when forming the film by reactive sputtering, the power applied to the sputtering target, and the positional relationship such as the distance between the target and the light-transmitting substrate 1. These film formation conditions are specific to the film formation device and are appropriately adjusted so that the thin film formed has the desired refractive index n and extinction coefficient k.

[0044] The phase shift film 2 is formed of a material containing a nonmetallic element and silicon. A thin film formed of a material containing silicon and a transition metal tends to have a high extinction coefficient k. In order to reduce the overall thickness of the phase shift film 2, the phase shift film 2 may be formed of a material containing a nonmetallic element, silicon, and a transition metal. In this case, the transition metal to be contained may be, for example, any one of molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), vanadium (V), zirconium (Zr), ruthenium (Ru), rhodium (Rh), zinc (Zn), niobium (Nb), palladium (Pd), etc., or an alloy of these metals. On the other hand, the phase shift film 2 is preferably formed of a material consisting of a nonmetallic element and silicon, or a material consisting of a semimetallic element, a nonmetallic element, and silicon.

[0045] When phase shift film 2 contains a metalloid element, it is preferable to contain one or more metalloid elements selected from boron, germanium, antimony, and tellurium, since this is expected to increase the electrical conductivity of silicon used as a sputtering target. When the phase shift film 2 contains a nonmetallic element, it is preferable that the phase shift film 2 contains one or more nonmetallic elements selected from nitrogen, oxygen, carbon, fluorine, and hydrogen. The nonmetallic elements include noble gases such as helium (He), argon (Ar), krypton (Kr), and xenon (Xe). In the overall composition of the phase shift film 2, the total content of nitrogen and oxygen is preferably 40 atomic % or more, and more preferably 50 atomic % or more.

[0046] The phase shift film 2 may be formed of a material containing a metal element and oxygen. In this case, the metal element to be contained may be, for example, any one of zirconium (Zr), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), molybdenum (Mo), hafnium (Hf), nickel (Ni), vanadium (V), ruthenium (Ru), rhodium (Rh), zinc (Zn), niobium (Nb), palladium (Pd), etc., or an alloy of these metals. In this case, the oxygen content of the phase shift film 2 is preferably 40 atomic % or more, and more preferably 50 atomic % or more.

[0047] In this embodiment, an intermediate film 3 containing silicon and oxygen is provided between the phase shift film 2 and the transmittance adjusting film 4. This intermediate film 3 functions as an etching stopper film for the phase shift film 2, and it is sufficient that the film has a thickness sufficient to function as an etching mask until the dry etching for forming a pattern on the phase shift film 2 is completed. Although not particularly limited, the intermediate film 3 is preferably made of the same material as the substrate 1. By doing so, even if the exposed surface of the transparent substrate 1 is etched by the effect of the etching gas when forming a pattern on the phase shift film 2 by dry etching, the intermediate film 3 is also etched to the same extent. Therefore, when the phase shift pattern is formed, the phase difference between the exposure light transmitted through the exposed portion of the transparent substrate 1 and the exposure light transmitted through the phase shift film 2 (and the intermediate film 3) is ensured within the above-mentioned preferred range. Thus, the mask blank of this embodiment is preferable in that the reliability of the phase shift function can be improved by providing the intermediate film 3. The oxygen content of the intermediate film 3 is preferably 50 atomic % or more, more preferably 55 atomic % or more, and even more preferably 60 atomic % or more. The thickness of the intermediate film 3 is preferably 1 nm or more, and more preferably 2 nm or more, and is preferably 10 nm or less, and more preferably 5 nm or less.

[0048] The mask blank 10 has a transmittance adjusting film 4 on an intermediate film 3. The transmittance adjusting film 4 has a refractive index at the wavelength of the exposure light of n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d U When expressed as [nm], the relationship of both the following formula (1) and formula (2) is satisfied. Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U3 +19.48×k U 2 -43.58×k U +38.11 As described above, a transmittance adjustment film 4 that satisfies formula (1) can satisfy the condition that the increase in phase difference between the exposure light that has transmitted through the phase shift film 2 and the laminated structure of the phase shift film 2 and the transmittance adjustment film 4 is 20 degrees or less compared to the exposure light that has transmitted through the phase shift film 2. A transmittance adjustment film 4 that satisfies formula (2) can satisfy the condition that the ratio of the transmittance of the exposure light that has transmitted through the laminated structure of the phase shift film 2 and the transmittance adjustment film 4 to the transmittance of the exposure light that has transmitted through the phase shift film 2 is 0.50 or less.

[0049] In addition, the refractive index n of the transmittance adjusting film 4 U is preferably 1.2 or more, and more preferably 1.5 or more. U is preferably 3.0 or less, and more preferably 2.5 or less. U is preferably 1.5 or more, and more preferably 2.0 or more. U is preferably 3.0 or less, and more preferably 2.5 or less. In addition, the extinction coefficient k U and thickness d U It is preferable that [nm] satisfies the relationship of the following formula (3). Formula (3) d U ≦8.646×k U 2 -38.42×k U +61.89

[0050] The process of derivation of this formula (3) will be described. The present inventors have studied the conditions under which the transmittance through the phase shift film 2 and the transmittance adjustment film 4 (hereinafter, this may be referred to as laminate transmittance) is 2% or more when the transmittance adjustment film 4 is provided on the phase shift film 2 having a transmittance of 12% or more. In this study, the present inventors have focused on the relationship between the maximum film thickness of the transmittance adjustment film and the extinction coefficient k, and performed optical simulations A3 and B3 for the phase shift film and the transmittance adjustment film, respectively. In the optical simulations A3 and B3, the maximum film thickness of the transmittance adjustment film was calculated to satisfy the laminate transmittance of 2% or more while changing the film thickness of the transmittance adjustment film within the range of the extinction coefficient k from 1.5 to 2.0. Note that, regarding the phase shift film, the same one as in the optical simulations A1 and A2 was used in the optical simulation A3, and the same one as in the optical simulations B1 and B2 was used in the optical simulation B3.

[0051] Then, based on the results of the simulations A3 and B3, the relationship between the extinction coefficient k and the maximum film thickness of the transmittance adjustment film was organized. FIG. 12 is a diagram comparing the results of the optical simulations A3 and B3 regarding the relationship between the maximum film thickness of the transmittance adjustment film and the extinction coefficient k. The curves A31 and A32 shown in FIG. 12 are the results of the optical simulation A3, and respectively indicate the maximum film thicknesses of the transmittance adjustment film for satisfying that the laminate transmittance is 2% or more and 4% or more, respectively. The curves B31 and B32 are the results of the optical simulation B2, and respectively indicate the maximum film thicknesses of the transmittance adjustment film for satisfying that the laminate transmittance is 2% or more and 4% or more, respectively.

[0052] The relational expression (the mathematical expression of curve A31) of the maximum film thickness of the transmittance adjusting film for satisfying that the laminate transmittance is 2% or more, shown in FIG. 12, is as follows: d Umax =8.646×k U 2 -38.42×k U +61.89 12, the curve A32, which satisfies that the laminate transmittance is 4% or more, is located below the curve A31. The relational expression (the mathematical expression of the curve A32) of the maximum film thickness of the transmittance adjusting film, which satisfies that the laminate transmittance is 4% or more, is as follows. d Umax =5.101×k U 2 -22.46×k U +38.44

[0053] From these results, the thickness of the transmittance control film d U [nm] and the extinction coefficient k U But, Formula (3) d U ≦8.646×k U 2 -38.42×k U +61.89 It was found that when the above condition is satisfied, the transmittance of the laminate is 2% or more. In addition, the thickness of the transmittance adjusting film d U [nm] and the extinction coefficient k U But, Formula (3-A32) d U ≦5.101×k U 2 -22.46×k U +38.44 It was found that when the above condition is satisfied, the transmittance of the laminate is 4% or more.

[0054] In FIG. 11, curve A31 is below curve B31 (a threshold curve for a laminate transmittance of 2% or more). This indicates that a transmittance adjustment film that satisfies the relationship of formula (3) derived from curve A31 will have a laminate transmittance of 2% or more even when it is provided on the phase shift film used in optical simulation B3. Similarly, curve A32 is below curve B32 (a threshold curve for a laminate transmittance of 4% or more). This indicates that a transmittance adjustment film that satisfies the relationship of formula (3-A32) derived from curve A32 will have a laminate transmittance of 4% or more even when it is provided on the phase shift film used in optical simulation B3. These results mean that if the transmittance adjusting film satisfies the relationship of formula (3), the laminate transmittance will be 2% or more, regardless of the optical properties of the phase shift film provided therebelow.

[0055] The transmittance adjustment film 4 may be made of any material as long as the above optical characteristics can be obtained. The transmittance adjustment film 4 preferably contains silicon, and more preferably contains silicon and a nonmetallic element. In addition, the transmittance adjustment film 4 preferably contains silicon and nitrogen, since the desired characteristics can be easily obtained. The transmittance adjustment film 4 preferably has a total silicon and nitrogen content of 97 atomic % or more, and even more preferably 99 atomic % or more.

[0056] The mask blank 10 has a configuration in which a light-shielding film 5 is provided on a transmittance adjusting film 4. The light-shielding film 5 needs to be made of a material that has sufficient etching selectivity with respect to an etching gas used when forming a pattern on the transmittance adjusting film 4. In this case, the light-shielding film 5 is preferably made of a material containing chromium. Examples of the chromium-containing material for forming the light-shielding film 5 include chromium metal, as well as materials containing chromium and one or more elements selected from oxygen, nitrogen, carbon, boron, and fluorine.

[0057] Generally, chromium-based materials are etched with a mixed gas of chlorine-based gas and oxygen gas, but the etching rate of chromium metal with respect to this etching gas is not very high. In consideration of increasing the etching rate with the mixed gas of chlorine-based gas and oxygen gas, the material for forming the light-shielding film 5 is preferably a material containing chromium and one or more elements selected from oxygen, nitrogen, carbon, boron, and fluorine. In addition, the chromium-containing material for forming the light-shielding film 5 may contain one or more elements of molybdenum, indium, and tin. By containing one or more elements of molybdenum, indium, and tin, the etching rate with respect to the mixed gas of chlorine-based gas and oxygen gas can be made faster.

[0058] On the other hand, the light-shielding film 5 may have a structure in which a layer made of a material containing chromium and a layer made of a material containing silicon are laminated in this order from the transmittance adjusting film 4 side. In this case, specific details of the material containing chromium are the same as those in the light-shielding film 5 described above.

[0059] In the mask blank 10, it is preferable to further laminate a hard mask film 6 made of a material having etching selectivity to the etching gas used when etching the light-shielding film 5 on the light-shielding film 5. Since the hard mask film 6 is basically not limited by optical density, the thickness of the hard mask film 6 can be significantly thinner than the thickness of the light-shielding film 5. The resist film 7 made of an organic material only needs to have a thickness that is sufficient to function as an etching mask until the dry etching that forms a pattern on the hard mask film 6 is completed. Therefore, the resist film 7 can be significantly thinner than the conventional one. Thinning the resist film 7 is effective in improving resist resolution and preventing pattern collapse, and is extremely important in responding to demands for finer processing.

[0060] When the light-shielding film 5 is made of a material containing chromium, the hard mask film 6 is preferably made of a material containing silicon. In this case, the hard mask film 6 tends to have low adhesion to a resist film made of an organic material. For this reason, it is preferable to treat the surface of the hard mask film 6 with HMDS (Hexamethyldisilazane) to improve the adhesion of the surface. In this case, the hard mask film 6 is more preferably made of SiO2, SiN, SiON, or the like.

[0061] In addition, when the light-shielding film 5 is made of a material containing chromium, the material of the hard mask film 6 may be made of a material containing tantalum in addition to the above. In this case, the material containing tantalum may be tantalum metal, or a material containing tantalum and one or more elements selected from nitrogen, oxygen, boron, and carbon. For example, Ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, TaBOCN, etc. are included. In addition, when the light-shielding film 5 is made of a material containing silicon, the hard mask film 6 is preferably made of the material containing chromium.

[0062] In the mask blank 10, the resist film 7 made of an organic material is preferably formed with a thickness of 100 nm or less in contact with the surface of the hard mask film 6. In the case of a fine pattern corresponding to the DRAM hp32 nm generation, a transfer pattern (phase shift pattern) to be formed on the hard mask film 6 may be provided with a SRAF (Sub-Resolution Assist Feature) with a line width of 40 nm. However, even in this case, the cross-sectional aspect ratio of the resist pattern can be made low at 1:2.5, so that the resist pattern can be prevented from collapsing or detaching during development, rinsing, etc. of the resist film 7. It is more preferable that the resist film 7 has a thickness of 80 nm or less. When the hard mask film 6 is formed of a material containing silicon, it is preferable to perform a silylation treatment using HMDS (Hexamethyldisilazane) or the like on the surface of the hard mask film 6 before forming the resist film.

[0063] The phase shift film 2, intermediate film 3, transmittance adjusting film 4, light shielding film 5, and hard mask film 6 are formed by sputtering, and any of sputtering methods such as DC sputtering, RF sputtering, and ion beam sputtering can be used. When a target with low conductivity is used, it is preferable to apply RF sputtering or ion beam sputtering. Considering the film formation rate, it is more preferable to apply RF sputtering. Also, the resist film 7 is formed by a spin coating method.

[0064] Thus, the configuration of the mask blank 10 of this embodiment has been described with reference to FIG. 1, but the configuration is not limited thereto, and may be, for example, a mask blank having no intermediate film 3, hard mask film 6, or resist film 7. Also, the mask blank may be configured with an etching stopper film provided between the substrate 1 and the phase shift film 2. In this case, examples of the material for the etching stopper film include a material containing aluminum, silicon, and oxygen, a material containing aluminum, hafnium, and oxygen, a material containing hafnium and oxygen, and a material containing chromium. These points are the same in the mask blank of the second embodiment described later.

[0065] [Phase shift masks and their manufacturing] The phase shift mask 100 according to the first embodiment (see FIG. 2) includes a phase shift film (phase shift pattern) 2a having a first pattern on a light-transmitting substrate 1, and a transmittance adjustment film (transmittance adjustment pattern) 4b having a second pattern on the phase shift pattern 2a. An intermediate film (intermediate pattern) 3b having a second pattern is provided between the phase shift pattern 2a and the transmittance adjustment pattern 4b. A light-shielding film (light-shielding pattern) 5c having a third pattern is provided on the transmittance adjustment film 4b.

[0066] That is, phase shift mask 100 according to the first embodiment comprises phase shift pattern 2a on light-transmitting substrate 1, and comprises intermediate pattern 3b, transmittance adjusting pattern 4b, and light-shielding pattern 5c on phase shift pattern 2a. Phase shift pattern 2a generates a phase difference of 150 degrees or more and 210 degrees or less between ArF excimer laser exposure light that has passed through phase shift pattern 2a and exposure light that has passed through air a distance equal to the thickness of phase shift pattern 2a, and sets the refractive index of transmittance adjusting pattern 4b at the wavelength of exposure light to n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d U When expressed as [nm], it is characterized in that the relationship of both the following formula (1) and formula (2) is satisfied. Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11 In phase shift mask 100, the specific configurations of light-transmitting substrate 1, phase shift pattern 2a, intermediate pattern 3b, transmittance adjusting pattern 4b, and light-shielding pattern 5c are the same as those in mask blank .

[0067] A method for manufacturing phase shift mask 100 according to the first embodiment will be described below in accordance with the manufacturing steps shown in FIGS. 3 and 4, which are schematic cross-sectional views of essential parts. A first pattern to be formed in the phase shift film 2 is written by an electron beam on the resist film 7 formed by spin coating on the mask blank 10 shown in Fig. 1, and then a resist film (resist pattern) 7a having the first pattern is formed by carrying out predetermined processes such as development (see Fig. 3(a)). This first pattern includes a phase shift pattern for achieving a phase shift effect by being formed in the phase shift film 2, and a pattern for an alignment mark (the opening on the left side of Fig. 2). Next, using the first resist pattern 7a as a mask, the hard mask film 6 is dry etched using a fluorine-based gas to form a hard mask film (hard mask pattern) 6a having a first pattern (see FIG. 3(b)).

[0068] Next, the light-shielding film 5 is dry-etched using a mixture of chlorine-based gas and oxygen-based gas with the first resist pattern 7a and the hard mask pattern 6a as masks to form a light-shielding film (light-shielding pattern) 5a having a first pattern (see FIG. 3(c)). Next, the first resist pattern 7a is removed and a cleaning process is performed, and the transmittance adjusting film 4, the intermediate film 3, and the phase shift film 2 are dry-etched using a fluorine-based gas with the light-shielding pattern 5a and the hard mask pattern 6a as masks to form a transmittance adjusting film (transmittance adjusting pattern) 4a having a first pattern, an intermediate film (intermediate pattern) 3a having a first pattern, and a phase shift film (phase shift pattern) 2a' partially having the first pattern (see FIG. 3(d)). The hard mask pattern 6a is removed by this dry etching. In addition, in the dry etching of this phase shift film 2, in the process of forming the transmittance adjustment pattern 4b in the transmittance adjustment film 4 by dry etching, which will be described later, it is preferable to adjust the thickness of the remaining portion of the phase shift film 2a' so that the remaining portion of the phase shift film 2a' is removed at almost the same time when the formation of the transmittance adjustment pattern 4b is completed.

[0069] Next, a resist film is formed by spin coating. After that, a pattern to be formed on the transmittance adjusting film 4 is drawn on the resist film with an electron beam, and a predetermined process such as development is further performed to form a resist film (resist pattern) 8b having a second pattern (see FIG. 4(a)). After that, using the resist pattern 8b as a mask, dry etching is performed on the light-shielding film 5a using a mixed gas of chlorine gas and oxygen gas, to form a light-shielding film (light-shielding pattern 5b) having the second pattern (see FIG. 4(a)).

[0070] Then, the resist pattern 8b is removed and a cleaning process is performed, and the transmittance adjustment film 4 is dry-etched using a fluorine-based gas with the light-shielding pattern 5b as a mask to form a transmittance adjustment film (transmittance adjustment pattern) 4b having a second pattern (see FIG. 4(b)). At this time, the exposed remaining portion of the phase shift film (phase shift pattern) 2a' partially having the first pattern is also removed to form a phase shift film (phase shift pattern) 2a' having the first pattern (see FIG. 4(b)).

[0071] Then, using the light-shielding pattern 5b and the transmittance adjusting pattern 4b as a mask, the intermediate pattern 3a is dry-etched (over-etched) using a fluorine-based gas to form an intermediate film (intermediate pattern) 3b having a second pattern (see FIG. 4(c)). At this time, the exposed portion of the light-transmitting substrate 1 may be dug up by the fluorine-based gas, but since the intermediate film 3 is made of the same material as the light-transmitting substrate 1 as described above, it is possible to ensure a desired phase difference between the exposed portion of the light-transmitting substrate 1 and the exposed portion of the phase shift pattern 2a.

[0072] Then, a resist film is formed by spin coating. After that, a pattern to be formed on the light-shielding film 5 is drawn on the resist film with an electron beam, and a predetermined process such as development is performed to form a resist film (resist pattern) 9c having a third pattern (see FIG. 4(d)). After that, using the resist pattern 9c as a mask, the light-shielding pattern 5b is dry-etched using a mixed gas of chlorine gas and oxygen gas to form a light-shielding film (light-shielding pattern) 5c having the third pattern (see FIG. 4(d)). Thereafter, resist pattern 9c is removed and a cleaning step is performed, thereby completing the manufacture of phase shift mask 100 shown in FIG.

[0073] [Semiconductor device manufacturing] The method for manufacturing a semiconductor device of the first embodiment is characterized in that a transfer pattern is exposed and transferred to a resist film on a semiconductor substrate using phase shift mask 100 of the first embodiment or phase shift mask 100 manufactured using mask blank 10 of the first embodiment. Therefore, when phase shift mask 100 of the first embodiment is used to expose and transfer a pattern to a resist film on a semiconductor device, a pattern can be formed on the resist film on the semiconductor device with an accuracy that fully satisfies the design specifications.

[0074] <Second embodiment> [Mask blanks and their manufacturing] Fig. 5 is a cross-sectional view showing the configuration of a mask blank 20 according to a second embodiment of the present invention. The mask blank 20 shown in Fig. 5 differs from the mask blank 10 shown in Fig. 1 in that the phase shift film 15 has a three-layer structure in which a first layer 12, a second layer 13, and a third layer 14 are laminated, and a transmittance adjustment film 16 is provided on the phase shift film 15. Hereinafter, explanations of points common to the mask blank 10 of the first embodiment will be omitted as appropriate.

[0075] The phase shift film 15 in this embodiment is configured such that the refractive indices n1, n2, and n3 of the first layer 12, second layer 13, and third layer 14 at the wavelength of ArF exposure light satisfy the relationship n1>n2>n3, and the extinction coefficients k1, k2, and k3 of the first layer 12, second layer 13, and third layer 14 satisfy the relationship k1>k2>k3. In addition, the film thicknesses d1, d2, and d3 of the first layer 12, second layer 13, and third layer 14 satisfy the relationship d1>d2>d3. Phase shift film 15 is composed of first layer 12, second layer 13, and third layer 14 that satisfy such a relationship, and this allows the phase shift film to have a higher transmittance than phase shift film 2 in the first embodiment. The configuration of this phase shift film 15 includes the conditions of the phase shift film set during optical simulations B1, B2, and B3.

[0076] The phase shift film 15 may be made of the same material as the phase shift film 2 of the first embodiment. In the overall composition of the phase shift film 15, the total content of nitrogen and oxygen is preferably 40 atomic % or more, and more preferably 50 atomic % or more. The first layer 12 is preferably formed from a material containing silicon and nitrogen, the second layer 13 is preferably formed from a material containing silicon, oxygen, and nitrogen, and the top layer, the third layer 14, is preferably formed from a material containing silicon and oxygen.

[0077] Also, the transmittance adjustment film 16 is laminated on the phase shift film 15, which is different from the transmittance adjustment film 4 in the first embodiment. Other conditions to be satisfied are similar to those of the transmittance adjustment film 4 in the first embodiment.

[0078] As described above, the mask blank 20 in this embodiment has the transmittance adjusting film 16 on the phase shift film 15. The transmittance adjusting film 16 has a refractive index at the wavelength of the exposure light of n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d UWhen expressed as [nm], the relationship of both the following formula (1) and formula (2) is satisfied. Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11 As described above, if the transmittance adjustment film 16 satisfies the formula (1), it can satisfy the condition that the increase in phase difference between the exposure light transmitted through the phase shift film 15 and the laminated structure of the phase shift film 15 and the transmittance adjustment film 16 is 20 degrees or less compared to the exposure light transmitted through the phase shift film 15. If the transmittance adjustment film 16 satisfies the formula (2), it can satisfy the condition that the ratio of the transmittance of the exposure light transmitted through the laminated structure of the phase shift film 15 and the transmittance adjustment film 16 to the transmittance of the exposure light transmitted through the phase shift film 15 is 0.50 or less.

[0079] [Phase shift masks and their manufacturing] The phase shift mask 200 (see FIG. 6) according to the second embodiment includes a phase shift film (phase shift pattern) 15a having a first pattern on a light-transmitting substrate 1, and a transmittance adjustment film (transmittance adjustment pattern) 16b having a second pattern on the phase shift pattern 15a. The phase shift pattern 15a also includes a third layer 14a having the first pattern, which is the top layer containing silicon and oxygen, on the surface side opposite to the light-transmitting substrate 1. A light-shielding film (light-shielding pattern) 5c having a third pattern is provided on the transmittance adjustment pattern 16b.

[0080] That is, phase shift mask 200 according to the second embodiment has phase shift pattern 15a on light-transmitting substrate 1, and has transmittance adjusting pattern 16b and light-shielding pattern 5c on phase shift pattern 15a. Phase shift pattern 15a generates a phase difference of 150 degrees or more and 210 degrees or less between ArF excimer laser exposure light that has passed through phase shift pattern 15a and exposure light that has passed through air a distance equal to the thickness of phase shift pattern 15a, and sets the refractive index of transmittance adjusting pattern 16b at the wavelength of exposure light to n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d U When expressed as [nm], it is characterized in that the relationship of both the following formula (1) and formula (2) is satisfied. Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11 In phase shift mask 200 , the specific configurations of light-transmitting substrate 1 , phase shift pattern 15 a , transmittance adjusting pattern 16 b , and light-shielding pattern 5 c are the same as those in mask blank 20 .

[0081] A method for manufacturing phase shift mask 200 according to the second embodiment will be described below in accordance with the manufacturing steps shown in FIGS. 7 and 8, which are schematic cross-sectional views of essential parts. A first pattern to be formed in the phase shift film 15 is written by an electron beam on the resist film 7 formed by spin coating on the mask blank 20 shown in Fig. 5, and then a resist film (resist pattern) 7a having the first pattern is formed by performing predetermined processes such as development (see Fig. 7(a)). This first pattern includes a phase shift pattern for achieving a phase shift effect by being formed in the phase shift film 15, and a pattern for an alignment mark (the opening on the left side of Fig. 6). Next, using the first resist pattern 7a as a mask, the hard mask film 6 is dry etched using a fluorine-based gas to form a hard mask film (hard mask pattern) 6a having a first pattern (see FIG. 7(b)).

[0082] Next, the light-shielding film 5 is dry-etched using a mixture of chlorine-based gas and oxygen-based gas with the first resist pattern 7a and the hard mask pattern 6a as masks to form a light-shielding film (light-shielding pattern) 5a having a first pattern (see FIG. 7(c)). Next, the first resist pattern 7a is removed and a cleaning process is performed, and the transmittance adjusting film 16 and the phase shift film 15 are dry-etched using a fluorine-based gas with the light-shielding pattern 5a and the hard mask pattern 6a as masks to form a transmittance adjusting film (transmittance adjusting pattern) 16a having the first pattern and a phase shift film (phase shift pattern) 15a' partially having the first pattern (see FIG. 7(d)). This phase shift pattern 15a' is composed of a first layer 12a' partially having the first pattern, a second layer 13a having the first pattern, and a third layer 14a having the first pattern. The hard mask pattern 6a is removed by this dry etching. In the dry etching of this phase shift film 15, it is preferable to adjust the thickness of the remaining portion of the phase shift film 15a' (first layer 12a') so that, in the process of forming the transmittance adjustment pattern 16b in the transmittance adjustment film 16 by dry etching, which will be described later, the remaining portion of the phase shift film 15a' (first layer 12a') is removed at almost the same time when the formation of the transmittance adjustment pattern 16b is completed.

[0083] Next, a resist film is formed by spin coating. After that, a pattern to be formed on the transmittance adjusting film 16 is drawn on the resist film with an electron beam, and a predetermined process such as development is further performed to form a resist film (resist pattern) 8b having a second pattern (see FIG. 8(a)). After that, using the resist pattern 8b as a mask, dry etching is performed on the light-shielding film 5a using a mixed gas of chlorine gas and oxygen gas to form a light-shielding film (light-shielding pattern 5b) having the second pattern (see FIG. 8(a)).

[0084] Then, the resist pattern 8b is removed and a cleaning process is performed, and the transmittance adjusting film 16 is dry-etched using a fluorine-based gas with the light-shielding pattern 5b as a mask to form a transmittance adjusting film (transmittance adjusting pattern) 16b having a second pattern (see FIG. 8(b)). At this time, the exposed remaining portion of the phase shift film (phase shift pattern) 15a' partially having the first pattern is also removed to form a phase shift film (phase shift pattern) 15a having the first pattern (see FIG. 8(b)).

[0085] Then, a resist film is formed by spin coating. After that, a pattern to be formed on the light-shielding film 5 is drawn on the resist film with an electron beam, and a predetermined process such as development is further performed to form a resist film (resist pattern) 9c having a third pattern (see FIG. 8(c)). After that, using the resist pattern 9c as a mask, the light-shielding pattern 5b is dry-etched using a mixed gas of chlorine gas and oxygen gas to form a light-shielding film (light-shielding pattern) 5c having the third pattern (see FIG. 8(c)). Thereafter, resist pattern 9c is removed and a cleaning step is performed, thereby completing the manufacture of phase shift mask 200 shown in FIG.

[0086] [Semiconductor device manufacturing] The method for manufacturing a semiconductor device according to the second embodiment includes the steps of:2 The feature of this embodiment is that a transfer pattern is exposed and transferred to a resist film on a semiconductor substrate using phase shift mask 200 manufactured using mask blank 20 of the second embodiment. Therefore, when phase shift mask 200 of the second embodiment is used to expose and transfer a pattern to a resist film on a semiconductor device, a pattern can be formed on the resist film on the semiconductor device with a precision that fully satisfies the design specifications.

[0087] <Third embodiment> [Mask blanks and their manufacturing] Fig. 13 is a cross-sectional view showing a configuration of a mask blank 30 according to a third embodiment of the present invention. The mask blank 30 shown in Fig. 13 differs from the mask blank 10 shown in Fig. 1 in that a transmittance adjusting film 41 is provided directly on the phase shift film 2, and that an etching stopper film 31 is disposed between the transmittance adjusting film 41 and the light-shielding film 5. Hereinafter, explanations of points common to the mask blank 10 of the first embodiment will be omitted as appropriate.

[0088] The transmittance adjustment film 41 in this embodiment is formed of a material containing chromium. This transmittance adjustment film 41 has sufficient etching selectivity with respect to the phase shift film 2, so a film equivalent to the intermediate film 3 in the first embodiment is not provided. The transmittance adjustment film 41 is preferably formed of a material containing chromium and one or more elements selected from oxygen, nitrogen, carbon, boron and fluorine. The transmittance adjustment film 41 may be made of a chromium-based material that is used for the light-shielding film 5. The refractive index n of this transmittance adjustment film 41 at the wavelength of the exposure light is U , the extinction coefficient k at the wavelength of the exposure light U , thickness d U [nm] is designed so as to satisfy both the relationships of the above formula (1) and formula (2).

[0089] In the present embodiment, when the light-shielding film 5 is formed of a material containing chromium, the etching stopper film 31 functions as an etching stopper when the light-shielding film 5 is patterned by dry etching. The etching stopper film 31 can be made of a material containing silicon. The etching stopper film 31 is preferably made of a material containing silicon and oxygen. On the other hand, the etching stopper film 31 can also be made of a material containing tantalum and oxygen. The thickness of the etching stopper film 31 is preferably 1 nm or more, and more preferably 2 nm or more. The thickness of the etching stopper film 31 is preferably 10 nm or less, and more preferably 5 nm or less. In the present embodiment, when the light-shielding film 5 is formed of a material containing silicon or a material containing tantalum, the etching stopper film 31 may not be provided.

[0090] As described above, the mask blank 30 in this embodiment has the transmittance adjusting film 41 on the phase shift film 2. The transmittance adjusting film 41 has a refractive index at the wavelength of the exposure light of n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d U When expressed as [nm], the relationship of both the following formula (1) and formula (2) is satisfied. Formula (1) d U ≦-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11 As described above, the transmittance adjustment film 41 that satisfies formula (1) can satisfy the condition that the increase in phase difference between the exposure light that has transmitted through the phase shift film 2 and the laminated structure of the phase shift film 2 and the transmittance adjustment film 41 is 20 degrees or less compared to the exposure light that has transmitted through the phase shift film 2. Furthermore, the transmittance adjustment film 41 that satisfies formula (2) can satisfy the condition that the ratio of the transmittance of the exposure light that has transmitted through the laminated structure of the phase shift film 2 and the transmittance adjustment film 41 to the transmittance of the exposure light that has transmitted through the phase shift film 2 is 0.50 or less.

[0091] [Phase shift masks and their manufacturing] In the phase shift mask 300 (see FIG. 14) according to the third embodiment, a phase shift film (phase shift pattern) 2a having a first pattern is provided on a light-transmitting substrate 1, and a transmittance adjusting film (transmittance adjusting pattern) 41b having a second pattern is provided on the phase shift pattern 2a. An etching stopper film (etching stopper pattern) 31b having the second pattern is provided on the transmittance adjusting pattern 41b. A light-shielding film (light-shielding pattern) 5c having a third pattern is provided on the etching stopper film 31b.

[0092] That is, phase shift mask 300 according to the third embodiment includes phase shift pattern 2a on light-transmitting substrate 1, and includes transmittance adjusting pattern 41b, etching stopper pattern 31b, and light-shielding pattern 5c on phase shift pattern 2a. Phase shift pattern 2a generates a phase difference of 150 degrees or more and 210 degrees or less between ArF excimer laser exposure light that has passed through phase shift pattern 2a and exposure light that has passed through air a distance equal to the thickness of phase shift pattern 2a, and sets the refractive index of transmittance adjusting pattern 41b at the wavelength of exposure light to n U , the extinction coefficient at the wavelength of the exposure light is k U , the thickness is d U When expressed as [nm], it is characterized in that the relationship of both the following formula (1) and formula (2) is satisfied. Formula (1) d U ≦-17.63×nU 3 +142.0×n U 2 -364.9×n U +315.8 Formula (2) d U ≧-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11 In the phase shift mask 300, the specific configurations of the light-transmitting substrate 1, the phase shift pattern 2a, the transmittance adjusting pattern 41b, the etching stopper pattern 31b, and the light-shielding pattern 5c are the same as those in the mask blank 30.

[0093] A method for manufacturing phase shift mask 300 according to the third embodiment will be described below in accordance with the manufacturing steps shown in FIGS. 15 and 16, which are schematic cross-sectional views of essential parts. A first pattern to be formed in the phase shift film 2 is written by an electron beam on the resist film 7 formed by spin coating on the mask blank 30 shown in Fig. 13, and then a resist film (resist pattern) 7a having the first pattern is formed by carrying out predetermined processes such as development (see Fig. 15(a)). This first pattern includes a phase shift pattern to be formed in the phase shift film 2 and to provide a phase shift effect. Next, using the first resist pattern 7a as a mask, the light-shielding film 5 is dry-etched using a mixed gas of a chlorine-based gas and an oxygen gas to form a light-shielding film (light-shielding pattern) 5a having a first pattern (see FIG. 15(b)).

[0094] Next, using the first resist pattern 7a and the light-shielding pattern 5a as a mask, the etching stopper film 31 is dry-etched using a fluorine-based gas to form an etching stopper film (etching stopper pattern) 31a having a first pattern (see FIG. 15(c)). Next, the first resist pattern 7a is removed and a cleaning process is performed. Subsequently, a resist film is formed by a spin coating method. After that, a pattern to be formed in the etching stopper film 31 and the transmittance adjusting film 41 is drawn on the resist film with an electron beam, and further a predetermined process such as a development process is performed to form a resist film (resist pattern) 8b having a second pattern (see FIG. 15(d)).

[0095] Next, the light-shielding film 5a is dry-etched using a mixed gas of chlorine-based gas and oxygen gas with the resist pattern 8b as a mask, to form a light-shielding film (light-shielding pattern 5b) having a second pattern (see FIG. 16(a)). At this time, the transmittance adjusting film 41 is also dry-etched using the etching stopper pattern 31a as a mask, to form a transmittance adjusting film (transmittance adjusting pattern) 41a having a first pattern. Next, the second resist pattern 8b is removed and a cleaning process is performed. Next, the phase shift film 2 is dry-etched using a fluorine-based gas with the transmittance adjusting pattern 41a as a mask, to form a phase shift film (phase shift pattern) 2a having a first pattern (see FIG. 16(b)). At this time, the etching stopper pattern 31a is also dry-etched using the light-shielding pattern 5b as a mask, to form an etching stopper film (etching stopper pattern) 31b having a second pattern.

[0096] Next, the second resist pattern 8b is removed and a cleaning process is performed. Then, a resist film is formed by spin coating. After that, a pattern to be formed in the light-shielding film 5 is drawn on the resist film with an electron beam, and a predetermined process such as a development process is performed to form a resist film (resist pattern) 9c having a third pattern (see FIG. 16(c)). Next, using the resist pattern 9c as a mask, dry etching is performed on the light-shielding film 5b using a mixed gas of a chlorine-based gas and an oxygen gas, forming a light-shielding film (light-shielding pattern 5c) having the third pattern (see FIG. 16(d)). At this time, dry etching is also performed on the transmittance adjustment pattern 41a using the etching stopper pattern 31b as a mask, and a transmittance adjustment film (transmittance adjustment pattern) 41b having the second pattern is formed. After that, the resist pattern 9c is removed and a cleaning process is performed. In this manner, the phase shift mask 300 shown in FIG. 14 can be manufactured.

[0097] [Semiconductor device manufacturing] The method for manufacturing a semiconductor device according to the third embodiment is characterized in that a transfer pattern is exposed and transferred to a resist film on a semiconductor substrate using phase shift mask 300 according to the third embodiment or a phase shift mask 300 manufactured using mask blank 30 according to the third embodiment. Therefore, when phase shift mask 300 according to the third embodiment is used to expose and transfer a resist film on a semiconductor device, a pattern can be formed on the resist film on the semiconductor device with an accuracy that fully satisfies the design specifications. EXAMPLES

[0098] The following examples further illustrate the embodiments of the present invention. Example 1 [Mask blank manufacturing] A light-transmitting substrate 1 was prepared, which was made of synthetic quartz glass and had a main surface with dimensions of about 152 mm x about 152 mm and a thickness of about 6.35 mm. The end faces and main surface of this light-transmitting substrate 1 were polished to a predetermined surface roughness, and then subjected to a predetermined cleaning process and drying process. When the optical characteristics of this light-transmitting substrate 1 were measured, the refractive index n was 1.556 and the extinction coefficient k was 0.00 at the wavelength of the ArF exposure light.

[0099] Next, the light-transmitting substrate 1 was placed in a film-forming sputtering device, and a phase shift film 2 (SiN film Si:N=34.8 atomic %:65.2 atomic %) made of silicon and nitrogen was formed in a thickness of 60.4 nm on the surface of the light-transmitting substrate 1 by reactive sputtering using a silicon (Si) target and a mixed gas of argon (Ar) gas and nitrogen (N2) as the sputtering gas. Next, an intermediate film 3 (SiO2 film) made of silicon and oxygen was formed in a thickness of 3.0 nm on the phase shift film 2 by reactive sputtering using a silicon (Si) target and a mixed gas of argon (Ar) and oxygen (O2) as the sputtering gas. Then, a transmittance adjustment film 4 made of silicon and nitrogen was formed in a thickness of 12.0 nm by reactive sputtering using a mixed gas of argon (Ar) and nitrogen (N2) as the sputtering gas.

[0100] A phase shift film was formed on another transparent substrate in the same manner, and the transmittance and phase difference for light with a wavelength of 193 nm were measured using a phase shift amount measuring device (MPM193 manufactured by Lasertec Corporation). The transmittance was 18.6% and the phase difference was 180.0 degrees (deg). A phase shift film and a transmittance adjustment film were formed on another transparent substrate in the same manner, and the transmittance and phase difference for light with a wavelength of 193 nm were measured. The transmittance was 6.1% and the phase difference was 180.0 degrees (deg). The intermediate film 3 is thin, having a thickness of 3 nm, and has a high transmittance like the transparent substrate, so the effect of the presence or absence of the intermediate film 3 on the transmittance and phase difference can be ignored.

[0101] Furthermore, when the optical properties of the phase shift film 2, the intermediate film 3, and the transmittance adjusting film 4 were measured, the phase shift film 2 had a refractive index n of 2.61 and an extinction coefficient k of 0.36, the intermediate film 3 had a refractive index n of 1.56 and an extinction coefficient k of 0.00, and the transmittance adjusting film 4 had a refractive index n U is 1.52, and the extinction coefficient k U was 2.09. The thickness d of these transmittance adjusting films 4 U [nm] and refractive index n U and the extinction coefficient k U The value of satisfies the relationship of any of formulas (1), (2), and (3).

[0102] Next, the light-transmitting substrate 1 on which the phase shift film 2, intermediate film 3, and transmittance adjusting film 4 were formed was placed in a film-forming sputtering device, and a light-shielding film 5 made of CrOC was formed to a thickness of 44 nm on the light-shielding film 4 by reactive sputtering using a chromium (Cr) target and a mixed gas of argon (Ar), carbon dioxide (CO2), and helium (He) as the sputtering gas. The optical density (OD) of this laminated structure of the phase shift film 2, intermediate film 3, transmittance adjusting film 4, and light-shielding film 5 for light with a wavelength of 193 nm was measured and found to be 3.0 or more.

[0103] Then, a hard mask film 6 made of silicon, nitrogen and oxygen was formed to a thickness of 12 nm on the light-shielding film 5 by reactive sputtering using a silicon (Si) target and a mixed gas of argon (Ar), oxygen (O2) and nitrogen (N2) as the sputtering gas for the light-shielding film 5 on the transparent substrate 1 on which the light-shielding film 5 was formed. Then, an HMDS treatment was applied to the surface of the hard mask film 6. Next, a resist film 7 made of a chemically amplified resist for electron beam writing was formed to a thickness of 80 nm on the surface of the hard mask film 6 by a spin coating method. By the above procedure, a mask blank 10 was manufactured having a structure in which a phase shift film 2, an intermediate film 3, a transmittance adjusting film 4, a light-shielding film 5, a hard mask film 6 and a resist film 7 were laminated on a light-transmitting substrate 1.

[0104] [Phase shift mask manufacturing] Next, using mask blank 10 of Example 1, phase shift mask 100 of Example 1 was produced according to the procedure of the phase shift mask manufacturing method described in the first embodiment.

[0105] The halftone phase shift mask 100 of Example 1 thus fabricated was set on a mask stage of an exposure apparatus using an ArF excimer laser as exposure light, and ArF exposure light was irradiated from the light-transmitting substrate 1 side of phase shift mask 100, thereby transferring a pattern to a resist film on a semiconductor device by exposure. This transferred pattern included a relatively fine pattern and a relatively sparse pattern. The resist film after exposure transfer was subjected to a prescribed process to form a resist pattern, which was then observed with a SEM (Scanning Electron Microscope). As a result, it was found that the desired transfer pattern was formed for each pattern. From this result, it can be said that it is possible to form a circuit pattern on a semiconductor device with high precision by using this resist pattern as a mask.

[0106] Example 2 [Mask blank manufacturing] The mask blank 20 of Example 2 was manufactured in the same manner as the mask blank 10 of Example 1, except that the phase shift film 15 has a three-layer structure formed by stacking a first layer 12, a second layer 13, and a third layer 14, and a transmittance adjustment film 16 is provided on top of this phase shift film 15. Specifically, in the mask blank 20 of Example 2, the first layer 12a of the phase shift film 15 is made of a material made of silicon and nitrogen, and has a refractive index n of 2.61 and an extinction coefficient k of 0.36 at a wavelength of 193 nm, and is formed to a thickness of 41 nm. The second layer 13a is made of a material made of silicon, oxygen, and nitrogen, and has a refractive index n of 2.18 and an extinction coefficient k of 0.12 at a wavelength of 193 nm, and is formed to a thickness of 24 nm. The third layer 14a is made of a material made of silicon and oxygen, and has a refractive index n of 1.56 and an extinction coefficient k of 0.00 at a wavelength of 193 nm, and is formed to a thickness of 4 nm. The transmittance adjustment film 16 is made of silicon and nitrogen, and has a refractive index n of 2.18 and an extinction coefficient k of 0.12 at a wavelength of 193 nm, and is formed to a thickness of 4 nm. Uis 1.52, and the extinction coefficient k U The material has a thickness of 2.09 and a thickness of 11.7 nm. U Therefore, the materials and manufacturing methods of the light-shielding film 5, the hard mask film 6, and the resist film 7 are the same as those in the first embodiment. The thickness d of the transmittance adjusting film 16 U [nm] and refractive index n U and the extinction coefficient k U The value of also satisfies the relationship of any of formulas (1), (2), and (3).

[0107] A phase shift film was formed on another transparent substrate in the same manner, and the transmittance and phase difference for light with a wavelength of 193 nm were measured using a phase shift amount measuring device (MPM193 manufactured by Lasertec Corporation). The transmittance was 28.0% and the phase difference was 180.0 degrees (deg.). A phase shift film and a transmittance adjustment film were formed on another transparent substrate in the same manner, and the transmittance and phase difference for light with a wavelength of 193 nm were measured. The transmittance was 6.0% and the phase difference was 178.0 degrees (deg.).

[0108] [Phase shift mask manufacturing] Next, using mask blank 20 of Example 2, phase shift mask 200 of Example 2 was produced according to the procedure of the phase shift mask manufacturing method described in the second embodiment.

[0109] The halftone phase shift mask 200 of Example 2 thus fabricated was set on a mask stage of an exposure apparatus using an ArF excimer laser as exposure light, and ArF exposure light was irradiated from the light-transmitting substrate 1 side of phase shift mask 200, thereby transferring a pattern to a resist film on a semiconductor device by exposure. This transferred pattern included a relatively fine pattern and a relatively sparse pattern. The resist film after exposure transfer was subjected to a prescribed process to form a resist pattern, which was then observed with a SEM (Scanning Electron Microscope). As a result, it was found that the desired transfer pattern was formed for each pattern. From this result, it can be said that it is possible to form a circuit pattern on a semiconductor device with high precision by using this resist pattern as a mask.

[0110] Example 3 [Mask blank manufacturing] A light-transmitting substrate 1 was prepared, which was made of synthetic quartz glass and had a main surface with dimensions of about 152 mm x about 152 mm and a thickness of about 6.35 mm. The end faces and main surface of this light-transmitting substrate 1 were polished to a predetermined surface roughness, and then subjected to a predetermined cleaning process and drying process. When the optical characteristics of this light-transmitting substrate 1 were measured, the refractive index n was 1.556 and the extinction coefficient k was 0.00 at the wavelength of the ArF exposure light.

[0111] Next, the light-transmitting substrate 1 was placed in a film-forming sputtering apparatus, and a phase shift film 2 (SiN film, Si:N=34.8 atomic %:65.2 atomic %) made of silicon and nitrogen was formed in a thickness of 60 nm on the surface of the light-transmitting substrate 1 by reactive sputtering using a silicon (Si) target and a mixed gas of argon (Ar) gas and nitrogen (N2) as the sputtering gas. Then, a transmittance adjustment film 41 made of CrOC was formed in a thickness of 11 nm on the phase shift film 2 by reactive sputtering using a chromium (Cr) target and a mixed gas of argon (Ar), carbon dioxide (CO2) and helium (He) as the sputtering gas. Then, an etching stopper film 31 (SiO2 film) made of silicon and oxygen was formed in a thickness of 3.0 nm on the transmittance adjustment film 41 by reactive sputtering using a silicon (Si) target and a mixed gas of argon (Ar) and oxygen (O2) as the sputtering gas.

[0112] A phase shift film was formed on another transparent substrate in the same manner, and the transmittance and phase difference for light with a wavelength of 193 nm were measured using a phase shift amount measuring device (MPM193 manufactured by Lasertec Corporation). The transmittance was 18.6% and the phase difference was 180.0 degrees (deg). A phase shift film and a transmittance adjustment film were formed on another transparent substrate in the same manner, and the transmittance and phase difference for light with a wavelength of 193 nm were measured. The transmittance was 6.0% and the phase difference was 191.0 degrees (deg). The etching stopper film 31 is thin, having a thickness of 3 nm, and has a high transmittance like the transparent substrate, so the influence of the presence or absence of the etching stopper film 31 on the transmittance and phase difference can be ignored.

[0113] Furthermore, when the optical characteristics of the phase shift film 2, the transmittance adjusting film 41, and the etching stopper film 31 were measured, the phase shift film 2 had a refractive index n of 2.61 and an extinction coefficient k of 0.36, and the transmittance adjusting film 41 had a refractive index n U is 1.82, and the extinction coefficient k U The refractive index of the etching stopper film 31 was 1.56 and the extinction coefficient k was 0.00. The thickness d of the transmittance adjusting film 41 U [nm] and refractive index n U and the extinction coefficient k U The value of satisfies the relationship of any of formulas (1), (2), and (3).

[0114] Next, a three-layered light-shielding film 5 was formed on the etching stopper film 31 to a thickness of 78 nm. Specifically, the light-transmitting substrate 1 on which the phase shift film 2, the transmittance adjusting film 41, and the etching stopper film 31 were formed was placed in a film-forming sputtering device, and a first layer made of CrOCN was formed to a thickness of 31 nm by reactive sputtering using a chromium (Cr) target and a mixed gas of argon (Ar), nitrogen (N2), carbon dioxide (CO2), and helium (He) as the sputtering gas. Next, a second layer made of CrOCN was formed to a thickness of 41 nm by reactive sputtering using a chromium (Cr) target and a mixed gas of argon (Ar), nitrogen (N2), carbon dioxide (CO2), and helium (He) as the sputtering gas. Furthermore, a third layer made of CrN was formed to a thickness of 6 nm by reactive sputtering using a chromium (Cr) target and a mixed gas of argon (Ar), nitrogen (N2), and helium (He) as the sputtering gas.

[0115] The optical density (OD) of the laminated structure of the phase shift film 2, the transmittance adjusting film 41, the etching stopper film 31 and the light-shielding film 5 for light with a wavelength of 193 nm was measured and found to be 3.2 or more. Then, a resist film 7 made of a chemically amplified resist for electron beam writing was formed to a thickness of 80 nm on the surface of the light-shielding film 5 by a spin coating method. By the above procedure, a mask blank 30 having a structure in which a phase shift film 2, a transmittance adjusting film 41, an etching stopper film 31, a light-shielding film 5 and a resist film 7 are laminated on a light-transmitting substrate 1 was manufactured.

[0116] [Phase shift mask manufacturing] Next, using mask blank 30 of Example 3, phase shift mask 300 of Example 3 was produced according to the procedure of the phase shift mask manufacturing method described in the third embodiment.

[0117] The halftone phase shift mask 300 of Example 3 thus fabricated was set on a mask stage of an exposure apparatus using an ArF excimer laser as exposure light, and ArF exposure light was irradiated from the light-transmitting substrate 1 side of phase shift mask 300, thereby transferring a pattern to a resist film on a semiconductor device by exposure. This transferred pattern included a relatively fine pattern and a relatively sparse pattern. The resist film after exposure transfer was subjected to a prescribed process to form a resist pattern, which was then observed with a SEM (Scanning Electron Microscope). As a result, it was found that the desired transfer pattern was formed for each pattern. From this result, it can be said that it is possible to form a circuit pattern on a semiconductor device with high precision by using this resist pattern as a mask. [Explanation of symbols]

[0118] 1. Transparent substrate, 2. Phase shift film 2a: Phase shift film having a first pattern (phase shift pattern) 2a' Phase shift film partially having a first pattern (phase shift pattern) 3 Interlayer 3a: Intermediate film having a first pattern (intermediate pattern) 3b Intermediate film having a second pattern (intermediate pattern) 4 Transmittance adjustment membrane 4a: Transmittance control film having a first pattern (transmittance control pattern) 4b: Transmittance adjusting film having a second pattern (transmittance adjusting pattern) 5. Light-shielding film 5a: Light-shielding film having a first pattern (light-shielding pattern) 5b Light-shielding film having a second pattern (light-shielding pattern) 5c Light-shielding film having a third pattern (light-shielding pattern) 6 Hard mask film 6a: Hard mask film having a first pattern (hard mask pattern) 7. Resist film 7a: Resist film having a first pattern (resist pattern) 8b Resist film having a second pattern (resist pattern) 9c: A resist film having a third pattern (resist pattern) 10 Mask Blanks 12 1st layer 12a: First layer having a first pattern 12a' First layer partially having a first pattern 13 2nd layer 13a: second layer having a first pattern 14 3rd layer 14a: a third layer having a first pattern 15 Phase shift film 15a: Phase shift film having a first pattern (phase shift pattern) 16 Transmittance adjustment membrane 16a: transmittance adjusting film having a first pattern (transmittance adjusting pattern) 16b: Transmittance adjusting film having a second pattern (transmittance adjusting pattern) 20 Mask Blanks 30 Mask Blanks 31 Etching stopper film 31a: Etching stopper film having a first pattern (etching stopper pattern) 31b: Etching stopper film having a second pattern (etching stopper pattern) 41 Transmittance adjustment membrane 41a: transmittance adjusting film having a first pattern (transmittance adjusting pattern) 41b: Transmittance adjusting film having a second pattern (transmittance adjusting pattern) 100 Phase Shift Mask 200 Phase Shift Mask 300 Phase Shift Mask

Claims

1. A mask blank having a phase shift film on a light-transmitting substrate, a transmittance adjusting film on the phase shift film, the phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between an exposure light of an ArF excimer laser that has passed through the phase shift film and the exposure light that has passed through air a distance equal to the thickness of the phase shift film, The refractive index of the transmittance adjusting film at the wavelength of the exposure light is n Ｕ , the extinction coefficient at the wavelength of the exposure light is k Ｕ , thickness is d Ｕ 2. A mask blank, characterized in that, when expressed as a distance (nm), it satisfies both of the following formulas (1) and (2): Formula (1) d Ｕ ≦-17.63×n Ｕ ３ +142.0×n Ｕ ２ -364.9×n Ｕ +315.8 Formula (2) d Ｕ ≧-2.805×k Ｕ ３ +19.48×k Ｕ ２ -43.58×k Ｕ +38.11

2. The refractive index n of the transmittance adjusting film Ｕ 2. The mask blank according to claim 1, wherein:

3. The extinction coefficient k of the transmittance adjusting film Ｕ 3. The mask blank according to claim 1, wherein:

4. 4. The mask blank according to claim 1, wherein the phase shift film transmits the exposure light with a transmittance of 12% or more.

5. The extinction coefficient k of the transmittance adjusting film Ｕ and the thickness d Ｕ 5. The mask blank according to claim 1, wherein [nm] satisfies the relationship of the following formula (3): Formula (3) d Ｕ ≦8.646×k Ｕ ２ -38.42×k Ｕ +61.89

6. 6. The mask blank according to claim 1, wherein the transmittance adjusting film contains silicon and nitrogen.

7. 7. The mask blank according to claim 1, further comprising an intermediate film containing silicon and oxygen between the phase shift film and the transmittance adjustment film.

8. 7. The mask blank according to claim 1, wherein the phase shift film comprises a top layer containing silicon and oxygen on a surface side opposite to the light-transmitting substrate side.

9. 9. The mask blank according to claim 1, further comprising a light-shielding film on the transmittance adjusting film.

10. A phase shift mask comprising a phase shift film having a first pattern on a light-transmitting substrate, a transmittance adjusting film having a second pattern on the phase shift film, the phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between an exposure light of an ArF excimer laser that has passed through the phase shift film and the exposure light that has passed through air a distance equal to the thickness of the phase shift film, The refractive index of the transmittance adjusting film at the wavelength of the exposure light is n Ｕ , the extinction coefficient at the wavelength of the exposure light is k Ｕ , thickness is d Ｕ 2. A phase shift mask, comprising: a first region (n) of a first electrode (n) and a second electrode (n) of a second electrode (n) that satisfy the relationship of the following formulas (1) and (2): Formula (1) d Ｕ ≦-17.63×n Ｕ ３ +142.0×n Ｕ ２ -364.9×n Ｕ +315.8 Formula (2) d Ｕ ≧-2.805×k Ｕ ３ +19.48×k Ｕ ２ -43.58×k Ｕ +38.11

11. The refractive index n of the transmittance adjusting film Ｕ 11. The phase shift mask according to claim 10, wherein: is 1.2 or more.

12. The extinction coefficient k of the transmittance adjusting film Ｕ 12. The phase shift mask according to claim 10, wherein is 1.5 or more.

13. 13. The phase shift mask according to claim 10, wherein the phase shift film transmits the exposure light with a transmittance of 12% or more.

14. The extinction coefficient k of the transmittance adjusting film Ｕ and the thickness d Ｕ 14. The phase shift mask according to claim 10, wherein [nm] satisfies the following formula (3): Formula (3) d Ｕ ≦8.646×k Ｕ ２ -38.42×k Ｕ +61.89

15. 15. The phase shift mask according to claim 10, wherein the transmittance adjusting film contains silicon and nitrogen.

16. 16. The phase shift mask according to claim 10, further comprising an intermediate film having the second pattern between the phase shift film and the transmittance adjustment film, the intermediate film containing silicon and oxygen.

17. 16. The phase shift mask according to claim 10, wherein the phase shift film has a top layer containing silicon and oxygen on a surface side opposite to the light-transmitting substrate side.

18. 18. The phase shift mask according to claim 10, further comprising a light-shielding film having a third pattern on said transmittance adjusting film.

19. A method for manufacturing a phase shift mask using the mask blank according to claim 9, comprising the steps of: forming a first pattern in the light-shielding film by dry etching; forming a first pattern in each of the transmittance adjustment film and the phase shift film by dry etching using the light-shielding film having the first pattern as a mask; forming a second pattern in the light-shielding film by dry etching; forming a second pattern in the transmittance adjusting film by dry etching using the light-shielding film having the second pattern as a mask; forming a third pattern in the light-shielding film by dry etching; 2. A method for manufacturing a phase shift mask comprising:

20. 20. A method for manufacturing a semiconductor device, comprising the step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the phase shift mask according to claim 18.

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