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

Abstract

The present invention provides a mask blank that can produce patterns with different transmittances with desired accuracy without complicating the mask manufacturing process, and that can achieve a desired phase shift function in each pattern. The mask blank includes a transmittance adjustment film on a phase shift film. The phase shift film creates a phase difference of 150 degrees or more and 210 degrees or less between ArF excimer laser exposure light after passing through the phase shift film and the exposure light after passing through air only at a distance equal to the thickness of the phase shift film. The refractive index of the transmittance adjustment film at the wavelength of the exposure light is set to n U , let the extinction coefficient at the wavelength of exposure light be k U , and set the thickness to d U [nm], the following equations (1) and (2) are satisfied at the same time. 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.

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 Art

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

[0003] As a type of transfer mask, in addition to conventional binary masks having a light-shielding pattern formed of a chromium-based material on a translucent substrate, halftone phase shift masks are also known. Molybdenum silicide (MoSi)-based materials are widely used in the phase shift films of halftone phase shift masks.

[0004] Patent Document 1 discloses a phase-shift mask having an etching stopper film 3 and a phase-shift layer 4 having a predetermined pattern formed in this order on a transparent substrate 2. A light-shielding film pattern 5 containing chromium is formed on the phase-shift layer 4 formed in region A, and a semi-transparent film pattern 6 composed of molybdenum silicide is formed on the phase-shift layer 4 formed in region B. Furthermore, a Levenson-type phase-shift mask and a half-tone-type phase-shift mask are formed on the same substrate.

[0005] Patent Document 2 discloses a phase-shift mask comprising: a halftone film 12 provided on portions of a light-transmitting substrate 11 where a light-shielding pattern is formed and portions where a semi-shielding pattern is formed; and a light-shielding film 13 provided on the halftone film 12 in the portion of the halftone film 12 where the light-shielding pattern is formed. The semi-shielding pattern includes a first semi-shielding pattern formed by the halftone film 12 and a second semi-shielding pattern formed by a halftone film having a smaller size than the first semi-shielding pattern. A light transmission path 32 in the region including the second semi-shielding pattern includes an element for adjusting the light transmittance of the light transmission path 32.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 6-123961

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2007-279441 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] In recent years, the types of patterns required have become increasingly diverse and complex. The transfer patterns formed on halftone phase-shift masks sometimes coexist with relatively fine patterns and relatively sparse patterns. The preferred transmittance for achieving a good phase-shift effect sometimes varies depending on the type of pattern. That is, there are cases where it is preferable to increase transmittance by adjusting the type and spacing of the transferred pattern, while there are cases where it is preferable to suppress transmittance. Furthermore, within the transfer region, how to set regions with relatively high transmittance and regions with relatively low transmittance varies depending on the semiconductor device being transferred. Therefore, a mask blank with a high degree of design freedom is required, allowing regions with desired transmittance to be set in accordance with the type of pattern being formed on the transfer target.

[0012] The phase-shift mask described in Patent Document 1 has a light-blocking film pattern formed in region A and a semi-transparent film pattern 5 formed in another region B. This phase-shift mask itself is useful. However, in a plan view, this phase-shift mask contains a mixture of patterns that produce different phase-shift effects: a Levenson-type phase-shift pattern in region A and a halftone-type phase-shift pattern in region B. This halftone-type phase-shift mask cannot meet the requirements for providing halftone-type phase-shift patterns with different transmittances.

[0013] Furthermore, the phase-shift mask described in Patent Document 2 employs a process that involves implanting Ga ions into a halftone mask blank to reduce the light transmittance of the implanted areas. Conventional mask manufacturing does not utilize this process, requiring the mask manufacturing apparatus to include an ion implantation mechanism, complicating the mask manufacturing process. Furthermore, the ions implanted into the mask blank diffuse away from the desired area, making it difficult to meet the requirements for producing fine patterns.

[0014] Therefore, the present invention has been made to solve existing problems. Its object is to provide a mask blank having a phase shift film on a light-transmitting substrate, without complicating the process (mask manufacturing process) for manufacturing a phase shift mask from the mask blank. The mask blank includes a phase shift film capable of producing patterns having different transmittances with desired accuracy, and capable of achieving a desired phase shift function in each pattern. Furthermore, the present invention aims to provide a phase shift mask manufactured using the mask blank and a method for manufacturing the phase shift mask. Furthermore, the present invention aims to provide a method for manufacturing a semiconductor device using such a phase shift mask.

[0015] Solutions to the problem

[0016] In order to achieve the above-mentioned problems, the present invention has the following means.

[0017] (Scheme 1)

[0018] A mask blank comprising a phase shift film on a light-transmitting substrate.

[0019] A transmittance adjustment film is provided on the phase shift film.

[0020] The phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between the exposure light of the ArF excimer laser after passing through the phase shift film and the exposure light after passing through the air only at a distance equal to the thickness of the phase shift film.

[0021] The refractive index of the transmittance adjustment film at the wavelength of the exposure light is n U , let the extinction coefficient at the wavelength of the exposure light be k U , and set the thickness to d U [nm], the following relationships (1) and (2) are satisfied simultaneously:

[0022] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0023] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11.

[0024] (Scheme 2)

[0025] The mask blank according to claim 1, wherein

[0026] The refractive index n of the transmittance adjustment film U is above 1.2.

[0027] (Scheme 3)

[0028] The mask blank according to claim 1 or 2, wherein:

[0029] The extinction coefficient k of the transmittance adjustment film U It is above 1.5.

[0030] (Scheme 4)

[0031] The mask blank according to any one of aspects 1 to 3, wherein

[0032] The phase shift film transmits the exposure light at a transmittance of 12% or more.

[0033] (Scheme 5)

[0034] The mask blank according to any one of aspects 1 to 4, wherein

[0035] The extinction coefficient k of the transmittance adjustment film U With the above thickness d U [nm] satisfies the following relationship (3),

[0036] Formula (3)d U ≤8.646×k U 2 -38.42×k U +61.89.

[0037] (Scheme 6)

[0038] The mask blank according to any one of aspects 1 to 5, wherein

[0039] The transmittance adjustment film contains silicon and nitrogen.

[0040] (Scheme 7)

[0041] The mask blank according to any one of aspects 1 to 6, wherein

[0042] An intermediate film containing silicon and oxygen is provided between the phase shift film and the transmittance adjustment film.

[0043] (Scheme 8)

[0044] The mask blank according to any one of aspects 1 to 6, wherein

[0045] The phase shift film includes an uppermost layer containing silicon and oxygen on a surface side opposite to the light-transmitting substrate side.

[0046] (Scheme 9)

[0047] The mask blank according to any one of aspects 1 to 8, wherein

[0048] A light-shielding film is provided on the transmittance adjustment film.

[0049] (Scheme 10)

[0050] A phase shift mask includes a phase shift film having a first pattern on a light-transmitting substrate.

[0051] A transmittance adjustment film having a second pattern is provided on the phase shift film.

[0052] The phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between the exposure light of the ArF excimer laser after passing through the phase shift film and the exposure light after passing through the air only at a distance equal to the thickness of the phase shift film.

[0053] The refractive index of the transmittance adjustment film at the wavelength of the exposure light is n U , let the extinction coefficient at the wavelength of the exposure light be k U , and set the thickness to d U [nm], the following relationships (1) and (2) are satisfied simultaneously:

[0054] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0055] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11.

[0056] (Scheme 11)

[0057] The phase-shift mask according to claim 10, wherein:

[0058] The refractive index n of the transmittance adjustment film U is above 1.2.

[0059] (Scheme 12)

[0060] The phase-shift mask according to claim 10 or 11, wherein:

[0061] The extinction coefficient k of the transmittance adjustment film U It is above 1.5.

[0062] (Scheme 13)

[0063] The phase-shift mask according to any one of items 10 to 12, wherein:

[0064] The phase shift film transmits the exposure light at a transmittance of 12% or more.

[0065] (Scheme 14)

[0066] The phase-shift mask according to any one of items 10 to 13, wherein:

[0067] The extinction coefficient k of the transmittance adjustment film U With the above thickness d U [nm] satisfies the following relationship (3),

[0068] Formula (3)d U ≤8.646×k U 2 -38.42×k U +61.89.

[0069] (Scheme 15)

[0070] The phase-shift mask according to any one of items 10 to 14, wherein:

[0071] The transmittance adjustment film contains silicon and nitrogen.

[0072] (Scheme 16)

[0073] The phase-shift mask according to any one of items 10 to 15, wherein:

[0074] An intermediate film having the second pattern is provided between the phase shift film and the transmittance adjustment film, and the intermediate film contains silicon and oxygen.

[0075] (Scheme 17)

[0076] The phase-shift mask according to any one of items 10 to 15, wherein:

[0077] The phase shift film includes an uppermost layer containing silicon and oxygen on a surface side opposite to the light-transmitting substrate side.

[0078] (Scheme 18)

[0079] The phase-shift mask according to any one of items 10 to 17, wherein:

[0080] A light-shielding film having a third pattern is provided on the transmittance adjustment film.

[0081] (Scheme 19)

[0082] A method for manufacturing a phase-shift mask using the mask blank according to claim 9, the method comprising:

[0083] forming a first pattern on the light-shielding film by dry etching;

[0084] forming a first pattern on 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;

[0085] forming a second pattern on the light-shielding film by dry etching;

[0086] forming a second pattern on the transmittance adjustment film by dry etching using the light-shielding film having the second pattern as a mask; and

[0087] A step of forming a third pattern on the light shielding film by dry etching.

[0088] (Scheme 20)

[0089] A method for manufacturing a semiconductor device, comprising the steps of: using the phase-shift mask according to claim 18 to transfer a transfer pattern by exposure to a resist film on a semiconductor substrate.

[0090] Effects of the Invention

[0091] The present invention can provide a mask blank that can produce patterns with different transmittances with desired accuracy without complicating the mask manufacturing process and can obtain a desired phase shift function in each pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 It is a cross-sectional view showing the structure of a mask blank in the first embodiment of the present invention.

[0093] Figure 2 It is a cross-sectional view showing the structure of the phase shift mask in the first embodiment of the present invention.

[0094] Figure 3 It is a schematic cross-sectional view of a main part showing the manufacturing process of the phase shift mask in the first embodiment of the present invention.

[0095] Figure 4 It is a schematic cross-sectional view of a main part showing the manufacturing process of the phase shift mask in the first embodiment of the present invention.

[0096] Figure 5 It is a cross-sectional view showing the structure of a mask blank in a second embodiment of the present invention.

[0097] Figure 6 It is a cross-sectional view showing the structure of a phase shift mask in a second embodiment of the present invention.

[0098] Figure 7 It is a schematic cross-sectional view of a main part showing a manufacturing process of a phase shift mask in a second embodiment of the present invention.

[0099] Figure 8 It is a schematic cross-sectional view of a main part showing a manufacturing process of a phase shift mask in a second embodiment of the present invention.

[0100] Figure 9This is a diagram showing the relationship between the maximum film thickness of the transmittance adjusting film and the refractive index n for satisfying the increase in retardation to be a predetermined value or less, which is derived from the results of optical simulation A1.

[0101] Figure 10 This is a diagram showing the relationship between the maximum film thickness of the transmittance adjusting film and the refractive index n for satisfying the increase in retardation to be a predetermined value or less, which is derived from the results of optical simulations A1 and B1.

[0102] Figure 11 This is a diagram showing the relationship between the minimum film thickness of the transmittance adjusting film and the extinction coefficient k for satisfying the transmittance ratio being a given value or less, which is derived from the results of optical simulations A2 and B2.

[0103] Figure 12 This diagram shows the relationship between the maximum thickness of the transmittance adjusting film and the extinction coefficient k for ensuring that the transmittance of exposure light after passing through the laminated structure of the phase shift film and the transmittance adjusting film is a given value or higher, derived from the results of optical simulations A3 and B3.

[0104] Figure 13 It is a cross-sectional view showing the structure of a mask blank in a third embodiment of the present invention.

[0105] Figure 14 It is a cross-sectional view showing the structure of a phase shift mask in a third embodiment of the present invention.

[0106] Figure 15 It is a schematic cross-sectional view of a main part showing a manufacturing process of a phase shift mask in a third embodiment of the present invention.

[0107] Figure 16 It is a schematic cross-sectional view of a main part showing a manufacturing process of a phase shift mask in a third embodiment of the present invention.

[0108] Explanation of symbols

[0109] 1 Translucent substrate

[0110] 2 Phase shift film

[0111] 2a Phase shift film having a first pattern (phase shift pattern)

[0112] 2a' Phase shift film partially having a first pattern (phase shift pattern)

[0113] 3 Intermediate film

[0114] 3a Intermediate film with first pattern (intermediate pattern)

[0115] 3b Intermediate film with second pattern (intermediate pattern)

[0116] 4 Transmittance adjustment film

[0117] 4a Transmittance Adjusting Film Having a First Pattern (Transmittance Adjusting Pattern)

[0118] 4b Transmittance Adjusting Film with Second Pattern (Transmittance Adjusting Pattern)

[0119] 5 shading film

[0120] 5a Light-shielding film having a first pattern (light-shielding pattern)

[0121] 5b Light-shielding film having a second pattern (light-shielding pattern)

[0122] 5c Light-shielding film having a third pattern (light-shielding pattern)

[0123] 6 Hard mask film

[0124] 6a Hard mask film having a first pattern (hard mask pattern)

[0125] 7. Resist film

[0126] 7a Resist film having a first pattern (resist pattern)

[0127] 8b Resist film having a second pattern (resist pattern)

[0128] 9c Resist film having a third pattern (resist pattern)

[0129] 10 Mask Blanks

[0130] 12 First Floor

[0131] 12a A first layer having a first pattern

[0132] 12a': first layer partially having a first pattern

[0133] 13 Second Floor

[0134] 13a The second layer having the first pattern

[0135] 14 Third Floor

[0136] 14a The third layer having the first pattern

[0137] 15 Phase shift film

[0138] 15a Phase shift film having a first pattern (phase shift pattern)

[0139] 16 Transmittance adjustment film

[0140] 16a Transmittance adjusting film having a first pattern (transmittance adjusting pattern)

[0141] 16b Transmittance adjusting film having a second pattern (transmittance adjusting pattern)

[0142] 20 Mask Blanks

[0143] 30 Mask Blanks

[0144] 31 Etching stop film

[0145] 31a Etching stop film having a first pattern (etching stop pattern)

[0146] 31b Etching stop film having a second pattern (etching stop pattern)

[0147] 41 Transmittance adjustment film

[0148] 41a Transmittance adjusting film having a first pattern (transmittance adjusting pattern)

[0149] 41b Transmittance adjusting film having a second pattern (transmittance adjusting pattern)

[0150] 100 Phase Shift Mask

[0151] 200 Phase Shift Mask

[0152] 300 Phase Shift Mask DETAILED DESCRIPTION

[0153] The present inventors have conducted extensive research on a technical approach to fabricate patterns of different transmittances with desired accuracy and achieve a desired phase shift function in each pattern without complicating the mask manufacturing process.

[0154] First, to create patterns with varying transmittances, a configuration was devised in which a transmittance adjustment film is provided on a phase shift film. Furthermore, the phase shift film has a function (hereinafter referred to as the "desired phase shift function") to produce a phase difference of 150 degrees to 210 degrees between ArF excimer laser exposure light after passing through the phase shift film and the exposure light after passing through air at a distance equal to the thickness of the phase shift film. This design allows ArF excimer laser exposure light (hereinafter referred to as "exposure light") to pass through the phase shift film at a predetermined transmittance in the areas of the phase shift mask where the transmittance adjustment film is removed, achieving the desired phase shift function.

[0155] On this basis, further research was conducted on the following structure of the transmittance adjustment film, which can also obtain the desired phase shift function for the exposure light passing through the phase shift film and the transmittance adjustment film, and can obtain a transmittance that is significantly different from the transmittance of the exposure light passing through the phase shift film.

[0156] First, regarding the phase shift function, the inventors investigated the conditions required to ensure that the increase in phase difference of exposure light transmitted through a stacked structure of a phase shift film and a transmittance adjustment film relative to the phase difference of exposure light transmitted through the phase shift film is 20 degrees or less. In this study, the inventors focused on the relationship between the maximum thickness of the transmittance adjustment film and its refractive index n, and conducted optical simulation A1 on the phase shift film and the transmittance adjustment film. In optical simulation A1, the maximum transmittance adjustment film thickness required to achieve a phase difference increase of 20 degrees or less was calculated while varying the transmittance adjustment film thickness while adjusting the refractive index n within the range of 1.2 to 2.0. Here, the phase shift film thickness was set to 60.4 nm, the refractive index n to 2.61, and the extinction coefficient k to 0.36. It should be noted that the refractive index n and extinction coefficient k described above are for the wavelength of ArF excimer laser light (193 nm), and the same applies to the following descriptions unless otherwise specified.

[0157] In optical simulation A1, an interlayer film was placed between the phase shift film and the transmittance adjustment film. This interlayer film was placed so that the phase shift film would not be etched into during patterning of the transmittance adjustment film using dry etching. The interlayer film had a thickness of 3 nm, a refractive index n of 1.56, and an extinction coefficient k of 0.00. Due to the interlayer film's optical properties, its effect on the results of optical simulation A1 was minimal.

[0158] Based on the results of the optical simulation A1, the relationship between the refractive index n and the maximum film thickness of the transmittance adjustment film was sorted out. Figure 9 This is a graph showing the relationship between the maximum film thickness of the transmittance adjusting film and the refractive index n, derived from the results of optical simulation A1, for satisfying the requirement that the increase in the phase difference of the exposure light passing through the phase shift film relative to the phase difference of the exposure light passing through the phase shift film is 20 degrees or less. Figure 9 Curves A11, A12, and A13 in FIG. 5 represent the maximum film thicknesses of the transmittance adjusting film for satisfying the increase in phase difference of 20 degrees or less, 15 degrees or less, and 10 degrees or less, respectively.

[0159] Figure 9 The relational expression (the mathematical expression of the curve A11 ) for the maximum film thickness of the transmittance adjusting film for satisfying the increase in the phase difference of 20 degrees or less is as follows.

[0160] d Umax =-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0161] In addition, if Figure 9 As shown, curves A12 and A13 satisfying the phase difference increase of 15 degrees or less and 10 degrees or less are located below curve A11. The relationship formula for the maximum film thickness of the transmittance adjusting film satisfying the phase difference increase of 15 degrees or less (the mathematical formula of curve A12) is as follows.

[0162] d Umax =-70.62×n U 3 +406.5×n U 2 -795.7×n U +540.1

[0163] The relational expression (the mathematical expression of the curve A13 ) for the maximum film thickness of the transmittance adjusting film for satisfying the requirement that the increase in phase difference is 10 degrees or less is as follows.

[0164] d Umax =201.1×n U 4 -1407×n U 3 +3700×n U 2 -4356×n U +1956

[0165] From these results, it was found that the thickness d of the transmittance adjustment film U [nm] and refractive index n U When formula (1) is satisfied, the increase in the phase difference of the exposure light passing through the laminated structure of the phase shift film and the transmittance adjustment film compared to the phase difference of the exposure light passing through the phase shift film is 20 degrees or less.

[0166] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0167] In addition, it was found that the thickness d of the transmittance adjustment film U [nm] and refractive index n U When formula (1-A12) is satisfied, the increase in the phase difference of the exposure light passing through the laminated structure of the phase shift film and the transmittance adjustment film relative to the phase difference of the exposure light passing through the phase shift film is 15 degrees or less.

[0168] Formula (1-A12)d U ≤-70.62×n U 3 +406.5×nU 2 -795.7×n U +540.1

[0169] Furthermore, it was found that the thickness d of the transmittance adjustment film U [nm] and refractive index n U When formula (1-A13) is satisfied, the increase in the phase difference of the exposure light passing through the stacked structure of the phase shift film and the transmittance adjustment film relative to the phase difference of the exposure light passing through the phase shift film is 10 degrees or less.

[0170] Formula (1-A13)d U ≤201.1×n U 4 -1407×n U 3 +3700×n U 2 -4356×n U +1956

[0171] Furthermore, the present inventors conducted the same optical simulation B1 by varying the conditions of the phase shift film. This phase shift film had a structure in which a first layer, a second layer, and a third layer were stacked in order from the translucent substrate side. The first layer had a thickness of 41 nm, a refractive index n of 2.61, and an extinction coefficient k of 0.36. The second layer had a thickness of 24 nm, a refractive index n of 2.18, and an extinction coefficient k of 0.12. The third layer had a thickness of 4 nm, a refractive index n of 1.56, and an extinction coefficient k of 0.00. It should be noted that in optical simulation B, since the third layer could also function as the aforementioned intermediate film, no intermediate film was provided between the phase shift film and the transmittance adjustment film. Based on the results of this optical simulation B1, the relationship between the refractive index n and the maximum film thickness of the transmittance adjustment film was analyzed.

[0172] Figure 10 This is a graph comparing the results of optical simulation A1 and optical simulation B1 with respect to the relationship between the maximum film thickness and the refractive index n of the transmittance adjustment film. Figure 10 The curves A11, A12 and A13 shown are the results of the optical simulation A1, and Figure 9 The results shown in the figure are the same. Figure 10 Curves B11 , B12 , and B13 are the results of the optical simulation B1 , and show the maximum thickness of the transmittance adjusting film required to satisfy the increase in retardation of 14 degrees or less, 11 degrees or less, and 6 degrees or less, respectively.

[0173] Figure 10In the figure, curve A11 is below curve B11 (the curve indicating a threshold value of 14 degrees for the increase in phase difference). This indicates that even when a transmittance adjustment film satisfying the relationship of equation (1) derived from curve A11 is provided on the phase shift film used in optical simulation B1, the increase in phase difference is 14 degrees or less. Similarly, curve A12 is below curve B12. This indicates that even when a transmittance adjustment film satisfying the relationship of equation (1-A12) derived from curve A12 is provided on the phase shift film used in optical simulation B1, the increase in phase difference is 11 degrees or less. Similarly, curve A13 is also below curve B13. This indicates that even when a transmittance adjustment film satisfying the relationship of equation (1-A13) derived from curve A13 is provided on the phase shift film used in optical simulation B1, the increase in phase difference is 6 degrees or less. These results indicate that if the transmittance adjustment film satisfies the relationship of formula (1), the increase in the retardation described above is 20 degrees or less regardless of the optical characteristics of the phase shift film provided thereunder.

[0174] On the other hand, as conditions for achieving a transmittance significantly different from the transmittance of exposure light passing through the phase shift film, the present inventors investigated conditions for achieving a transmittance ratio of 0.5 or less, based on the ratio of the transmittance Ts of exposure light passing through the laminated structure of the phase shift film and the transmittance adjustment film to the transmittance Tp of exposure light passing through the phase shift film (i.e., Ts / Tp, hereinafter sometimes referred to as the transmittance ratio). In this study, the present inventors focused on the relationship between the minimum thickness of the transmittance adjustment film and the extinction coefficient k, and conducted optical simulations A2 and B2 on the phase shift film and transmittance adjustment film, respectively. In optical simulations A2 and B2, the minimum thickness of the transmittance adjustment film required to achieve a transmittance ratio of 0.5 or less was calculated while varying the thickness of the transmittance adjustment film while adjusting the extinction coefficient k within the range of 1.5 to 2.0. Note that, for the phase shift film, the same phase shift film as used in optical simulation A1 was used in optical simulation A2, and the same phase shift film as used in optical simulation B1 was used in optical simulation B2.

[0175] Then, based on the results of the simulations A2 and B2, the relationship between the extinction coefficient k and the minimum film thickness of the transmittance adjusting film was sorted out. Figure 11 This graph compares the results of optical simulation A2 and optical simulation B2 with respect to the relationship between the minimum film thickness of the transmittance adjustment film and the extinction coefficient k. Figure 11 Curves A21 and A22 are the results of optical simulation A2, showing the minimum thicknesses of the transmittance adjusting film required to satisfy transmittance ratios of 0.50 or less and 0.45 or less, respectively. Curves B21 and B22 are the results of optical simulation B2, showing the minimum thicknesses of the transmittance adjusting film required to satisfy transmittance ratios of 0.50 or less and 0.43 or less, respectively.

[0176] Figure 11 The relational expression (the mathematical expression of the curve A21 ) for the minimum film thickness of the transmittance adjusting film for satisfying the transmittance ratio of 0.5 or less is as follows.

[0177] d Umin =-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0178] In addition, if Figure 11 As shown, curve A22 satisfying a transmittance ratio of 0.45 or less is located above curve A21. The relationship formula for the minimum film thickness of the transmittance adjusting film satisfying a transmittance ratio of 0.45 or less (the mathematical formula of curve A22) is as follows.

[0179] d Umin =8.592×k U 3 -38.60×k U 2 +54.28×k U -15.36

[0180] From these results, it was found that the thickness d of the transmittance adjustment film U [nm] and extinction coefficient k U When formula (2) is satisfied, the ratio of the transmittance of the exposure light passing through the laminated structure of the phase shift film and the transmittance adjustment film to the transmittance of the exposure light passing through the phase shift film is 0.5 or less.

[0181] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0182] In addition, it was found that the thickness d of the transmittance adjustment film U [nm] and extinction coefficient k U When formula (2-A22) is satisfied, the ratio of the transmittance of the exposure light passing through the laminated structure of the phase shift film and the transmittance adjustment film to the transmittance of the exposure light passing through the phase shift film is 0.45 or less.

[0183] Formula (2-A22)d U ≥8.592×k U 3 -38.60×k U2 +54.28×k U -15.36

[0184] Figure 11 In the figure, curve A21 lies above curve B21 (the curve with a transmittance ratio threshold of 0.50). This indicates that even when a transmittance adjustment film satisfying the relationship of equation (2) derived from curve A21 is placed on the phase shift film used in optical simulation B2, the transmittance ratio remains at or below 0.50. Similarly, curve A22 lies above curve B22 (the curve with a transmittance ratio threshold of 0.43). This indicates that even when a transmittance adjustment film satisfying the relationship of equation (2-A22) derived from curve A22 is placed on the phase shift film used in optical simulation B2, the transmittance ratio remains at or below 0.45. These results indicate that, if a transmittance adjustment film satisfies the relationship of equation (2), the transmittance ratio remains at or below 0.50, regardless of the optical properties of the underlying phase shift film.

[0185] As a result, the present inventors have found that if the transmittance adjusting film satisfies the relationship between equations (1) and (2), the increase in the retardation is 20 degrees or less, and the transmittance ratio is 0.50 or less. The present invention has been made through intensive research as described above.

[0186] <First embodiment>

[0187] [Mask Blank and Its Manufacturing]

[0188] Below, with reference to the attached Figure 1 The implementation method will be described.

[0189] Figure 1 It is a cross-sectional view showing the structure of the mask blank 10 according to the first embodiment of the present invention. Figure 1 The mask blank 10 of the present invention shown has a structure in which a phase shift film 2 , an intermediate film 3 , a transmittance adjustment film 4 , a light shielding film 5 , a hard mask film 6 , and a resist film 7 are sequentially stacked on a light-transmitting substrate 1 .

[0190] The transparent substrate 1 can be formed not only from synthetic quartz glass but also from quartz glass, aluminosilicate glass, soda-lime glass, low thermal expansion glass (e.g., SiO₂-TiO₂ glass), and the like. Of these, synthetic quartz glass has high transmittance to ArF excimer laser light and is particularly preferred as the material for the transparent substrate forming the mask blank. The refractive index n of the material forming the transparent substrate 1 at the wavelength of the ArF exposure light (approximately 193 nm) is preferably 1.5 to 1.6, more preferably 1.52 to 1.59, and even more preferably 1.54 to 1.58.

[0191] To achieve an appropriate phase shift effect, the phase shift film 2 is preferably adjusted so that the phase difference between the transmitted ArF exposure light and the light that has passed through air at a distance equal to the thickness of the phase shift film 2 is within a range of 150 degrees to 210 degrees. The phase difference in the phase shift film 2 is preferably 155 degrees or greater, more preferably 160 degrees or greater. On the other hand, the phase difference in the phase shift film 2 is preferably 195 degrees or less, more preferably 190 degrees or less.

[0192] The phase shift film 2 preferably allows exposure light to pass through with a transmittance of 12% or more. In recent years, NTD (Negative Tone Development) has begun to be used in the exposure / development process for resist films on semiconductor substrates (wafers), often employing bright field masks (transfer masks with high pattern aperture ratios). In bright field phase shift masks, setting the phase shift film's transmittance for exposure light to 12% or more improves the balance between zero-order and first-order light passing through the translucent portion. This improved balance causes the exposure light passing through the phase shift film to interfere with the zero-order light, increasing the effect of attenuating light intensity and improving the clarity of the pattern on the resist film. To further enhance the pattern edge enhancement effect of the transferred image (projected optical image) brought about by the phase shift effect, the phase shift film 2 preferably allows transmission at a transmittance of 19% or more, and more preferably at a transmittance of 28% or more. On the other hand, the transmittance of the phase shift film 2 for ArF exposure light is preferably 50% or less, and more preferably 40% or less. If the transmittance of the phase shift film 2 to ArF exposure light exceeds 50%, the influence of the side lobes becomes stronger, which is not preferable.

[0193] The thickness of the phase shift film 2 is preferably 90 nm or less, more preferably 80 nm or less. On the other hand, the thickness of the phase shift film 2 is preferably 40 nm or more, more preferably 50 nm or more.

[0194] In order to satisfy the various conditions related to the aforementioned optical properties and film thickness, the phase shift film 2 preferably has a refractive index n of 2.0 or greater, more preferably 2.1 or greater. Furthermore, the refractive index n of the phase shift film 2 is preferably 3.0 or less, more preferably 2.9 or less. The extinction coefficient k of the phase shift film 2 is preferably 0.9 or less, more preferably 0.6 or less. Furthermore, the extinction coefficient k of the phase shift film 2 is preferably 0.1 or greater.

[0195] The refractive index n and extinction coefficient k of the thin film including the phase shift film 2 are not determined solely by the composition of the thin film. The film density, crystallization state, etc. of the thin film are also factors that affect the refractive index n and extinction coefficient k. Therefore, the various conditions when forming the thin film by reactive sputtering are adjusted so that the film reaches the desired refractive index n and extinction coefficient k. In order to make the thin film reach the above-mentioned range of refractive index n and extinction coefficient k, it is not limited to adjusting the ratio of the mixed gas of rare gas and reactive gas (oxygen, nitrogen, etc.) when forming the film by reactive sputtering. It also involves many aspects such as the pressure in the film forming chamber when forming the film by reactive sputtering, the power applied to the sputtering target, the distance between the target and the translucent substrate 1, and other positional relationships. These film forming conditions are inherent conditions in the film forming device and can be appropriately adjusted so that the formed thin film reaches the desired refractive index n and extinction coefficient k.

[0196] The phase shift film 2 is formed from a material containing a non-metallic element and silicon. Thin films formed from materials containing silicon and a transition metal tend to have a higher extinction coefficient k. To reduce the overall thickness of the phase shift film 2, the phase shift film 2 can be formed from a material containing a non-metallic element, silicon, and a transition metal. Examples of the transition metals included in this case include 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), and alloys of these metals. On the other hand, the phase shift film 2 is preferably formed from a material containing a non-metallic element and silicon, or a material containing a semi-metallic element, a non-metallic element, and silicon.

[0197] When the phase shift film 2 contains a semi-metallic element, it is preferable to contain one or more semi-metallic elements selected from boron, germanium, antimony, and tellurium because this can be expected to improve the conductivity of silicon used as a sputtering target.

[0198] When the phase shift film 2 contains a non-metallic element, it preferably contains one or more non-metallic elements selected from nitrogen, oxygen, carbon, fluorine, and hydrogen. The non-metallic element may also include a rare gas such as helium (He), argon (Ar), krypton (Kr), and xenon (Xe).

[0199] In addition, the total content of nitrogen and oxygen in the entire composition of the phase shift film 2 is preferably 40 atomic % or more, and more preferably 50 atomic % or more.

[0200] The phase shift film 2 can be formed of a material containing a metal element and oxygen. Examples of the metal element in this case include 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), and alloys thereof. In this case, the oxygen content of the phase shift film 2 is preferably 40 atomic % or greater, and more preferably 50 atomic % or greater.

[0201] In this embodiment, an interlayer film 3 containing silicon and oxygen is provided between the phase shift film 2 and the transmittance adjustment film 4. This interlayer film 3 functions as an etching stopper for the phase shift film 2 and is sufficiently thick to function solely as an etching mask until the dry etching process for patterning the phase shift film 2 is completed. Furthermore, although not particularly limited, the interlayer film 3 is preferably made of the same material as the substrate 1. This ensures that, when patterning the phase shift film 2 using dry etching, even if the exposed surface of the transparent substrate 1 is etched by the etching gas, the interlayer film 3 is etched to the same extent. Therefore, when forming the phase shift pattern, 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 interlayer film 3) can be maintained within the preferred range described above. Therefore, the mask blank of this embodiment is preferred because the provision of the interlayer film 3 can enhance the reliability of the phase shift function. The oxygen content of the interlayer film 3 is preferably 50 atomic % or greater, more preferably 55 atomic % or greater, and even more preferably 60 atomic % or greater. The thickness of the intermediate film 3 is preferably 1 nm or more, more preferably 2 nm or more. The thickness of the intermediate film 3 is preferably 10 nm or less, more preferably 5 nm or less.

[0202] The mask blank 10 has a transmittance adjustment film 4 on an intermediate film 3. The refractive index of the transmittance adjustment film 4 at the wavelength of exposure light is represented by n. U , let the extinction coefficient at the wavelength of exposure light be k U , and set the thickness to d U When [nm], the following relationships of formula (1) and formula (2) are satisfied at the same time.

[0203] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0204] Formula (2)d U ≥-2.805×k U 3+19.48×k U 2 -43.58×k U +38.11

[0205] As described above, if the transmittance adjusting film 4 satisfies the formula (1), the condition that the increase in the phase difference of the exposure light transmitted through the laminated structure of the phase shift film 2 and the transmittance adjusting film 4 relative to the phase difference of the exposure light transmitted through the phase shift film 2 is 20 degrees or less can be satisfied. Furthermore, if the transmittance adjusting film 4 satisfies the formula (2), the condition that the ratio of the transmittance of the exposure light transmitted through the laminated structure of the phase shift film 2 and the transmittance adjusting film 4 relative to the transmittance of the exposure light transmitted through the phase shift film 2 is 0.50 or less can be satisfied.

[0206] In addition, the refractive index n of the transmittance adjustment film 4 is U It is preferably 1.2 or more, and more preferably 1.5 or more. U It is preferably 3.0 or less, and more preferably 2.5 or less. On the other hand, the extinction coefficient k of the transmittance adjustment film 4 is U It is preferably 1.5 or more, and more preferably 2.0 or more. U It is preferably 3.0 or less, and more preferably 2.5 or less.

[0207] In addition, the extinction coefficient k of the transmittance adjustment film 4 is U With thickness d U [nm] preferably satisfies the relationship of the following formula (3).

[0208] Formula (3)d U ≤8.646×k U 2 -38.42×k U +61.89

[0209] The process of deriving this formula (3) will be described. The present inventors studied the conditions under which the transmittance through the phase shift film 2 and the transmittance adjusting film 4 (hereinafter sometimes referred to as the laminate transmittance) is 2% or more when a transmittance adjusting film 4 is provided on a phase shift film 2 having a transmittance of 12% or more. In this study, the present inventors focused on the relationship between the maximum film thickness of the transmittance adjusting film and the extinction coefficient k, and performed optical simulations A3 and B3 on the phase shift film and the transmittance adjusting film, respectively. In optical simulations A3 and B3, the maximum film thickness of the transmittance adjusting film required to satisfy the transmittance of the laminate of 2% or more was calculated while changing the film thickness of the transmittance adjusting film while keeping the extinction coefficient k within the range of 1.5 to 2.0. It should be noted that, regarding the phase shift film, in optical simulation A3, the same phase shift film as in optical simulations A1 and A2 was used, and in optical simulation B3, the same phase shift film as in optical simulations B1 and B2 was used.

[0210] Next, 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 adjusting film was sorted out. Figure 12 This is a graph comparing the results of optical simulation A3 and optical simulation B3 with respect to the relationship between the maximum film thickness of the transmittance adjustment film and the extinction coefficient k. Figure 12 Curves A31 and A32 are the results of optical simulation A3, showing the maximum thickness of the transmittance-adjusting film required to achieve a laminate transmittance of 2% or greater and 4% or greater, respectively. Curves B31 and B32 are the results of optical simulation B2, showing the maximum thickness of the transmittance-adjusting film required to achieve a laminate transmittance of 2% or greater and 4% or greater, respectively.

[0211] Figure 12 The relational expression (the mathematical expression of the curve A31 ) for the maximum film thickness of the transmittance adjusting film for satisfying the transmittance of the laminate of 2% or more is as follows.

[0212] d Umax =8.646×k U 2 -38.42×k U +61.89

[0213] In addition, if Figure 12 As shown, curve A32, which satisfies the laminate transmittance of 4% or more, is located below curve A31. The relationship formula (the mathematical formula of curve A32) for the maximum thickness of the transmittance adjusting film for satisfying the laminate transmittance of 4% or more is as follows.

[0214] d Umax =5.101×k U 2 -22.46×k U +38.44

[0215] From these results, it was found that the thickness d of the transmittance adjustment film U [nm] and extinction coefficient k U When the formula (3) is satisfied, the transmittance of the laminate is 2% or more.

[0216] Formula (3)d U ≤8.646×k U 2 -38.42×k U +61.89

[0217] In addition, it was found that the thickness d of the transmittance adjustment film U [nm] and extinction coefficient k U When the formula (3-A32) is satisfied, the transmittance of the laminate is 4% or more.

[0218] Formula (3-A32)d U ≤5.101×k U 2 -22.46×k U +38.44

[0219] Figure 11 In the optical simulation B3, curve A31 lies below curve B31 (the curve indicating a threshold value of 2% or greater for the laminate transmittance). This indicates that even when a transmittance adjustment film satisfying the relationship of equation (3) derived from curve A31 is provided on the phase shift film used in optical simulation B3, the transmittance of the laminate remains at 2% or greater. Similarly, curve A32 lies below curve B32 (the curve indicating a threshold value of 4% or greater for the laminate transmittance). This indicates that even when a transmittance adjustment film satisfying the relationship of equation (3-A32) derived from curve A32 is provided on the phase shift film used in optical simulation B3, the transmittance of the laminate remains at 4% or greater.

[0220] These results indicate that if the transmittance adjustment film satisfies the relationship of formula (3), the transmittance of the laminate becomes 2% or more regardless of the optical characteristics of the phase shift film provided thereunder.

[0221] The transmittance adjusting film 4 may be made of any material as long as it achieves the aforementioned optical properties. The transmittance adjusting film 4 preferably contains silicon, and more preferably contains silicon and a non-metallic element. Furthermore, to facilitate obtaining the desired properties, the transmittance adjusting film 4 preferably contains silicon and nitrogen. The combined content of silicon and nitrogen in the transmittance adjusting film 4 is more preferably 97 atomic % or greater, and even more preferably 99 atomic % or greater.

[0222] The mask blank 10 has a configuration in which a light-shielding film 5 is provided on a transmittance adjustment film 4. The light-shielding film 5 must be made of a material having sufficient etching selectivity for the etching gas used when forming a pattern on the transmittance adjustment film 4. In this case, the light-shielding film 5 is preferably formed of a material containing chromium. Examples of the chromium-containing material forming the light-shielding film 5 include, in addition to chromium metal, materials containing chromium and one or more elements selected from oxygen, nitrogen, carbon, boron, and fluorine.

[0223] Generally, chromium materials are etched using a mixture of chlorine and oxygen gases, but the etching rate of chromium metal relative to this etching gas is not very high. To improve the etching rate of the etching gas relative to the mixture of chlorine and oxygen gases, the material forming the light-shielding film 5 is preferably one containing chromium at least one element selected from oxygen, nitrogen, carbon, boron, and fluorine. Alternatively, the chromium-containing material forming the light-shielding film 5 may contain at least one element selected from molybdenum, indium, and tin. By including at least one element selected from molybdenum, indium, and tin, the etching rate relative to the mixture of chlorine and oxygen gases can be further accelerated.

[0224] 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 stacked in this order from the transmittance adjusting film 4 side. The details of the material containing chromium in this case are the same as those of the light shielding film 5 described above.

[0225] The mask blank 10 preferably has a hard mask film 6 further laminated on the light-shielding film 5. The hard mask film 6 is formed from a material having etching selectivity for the etching gas used to etch the light-shielding film 5. Since the hard mask film 6 is essentially unrestricted by optical density, the thickness of the hard mask film 6 can be significantly thinner than that of the light-shielding film 5. Furthermore, the organic material resist film 7 is sufficient as long as it functions solely as an etching mask until the dry etching process for forming a pattern on the hard mask film 6 is completed. Therefore, the thickness of the resist film 7 can be significantly thinner than before. Thinning the resist film 7 is effective in improving resist resolution and preventing pattern distortion, and is extremely important in meeting the demand for miniaturization.

[0226] When the light-shielding film 5 is formed of a material containing chromium, the hard mask film 6 is preferably formed of a material containing silicon. It should be noted that in this case, the hard mask film 6 tends to have poor adhesion to organic resist films. Therefore, it is preferable to treat the surface of the hard mask film 6 with HMDS (hexamethyldisilazane) to improve surface adhesion. In this case, the hard mask film 6 is more preferably formed of SiO2, SiN, SiON, or the like.

[0227] Furthermore, when the light-shielding film 5 is formed of a material containing chromium, in addition to the above materials, a material containing tantalum can also be used as the material for the hard mask film 6. Examples of materials containing tantalum in this case include, in addition to tantalum metal, materials containing tantalum containing one or more elements selected from nitrogen, oxygen, boron, and carbon. Examples include Ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, and TaBOCN. Furthermore, when the light-shielding film 5 is formed of a material containing silicon, it is preferable that the hard mask film 6 be formed of the above-mentioned material containing chromium.

[0228] In the mask blank 10, a resist film 7 made of an organic material is preferably formed in contact with the surface of the hard mask film 6 with a film thickness of 100 nm or less. In the case of fine patterns corresponding to the 32 nm generation of DRAM, a SRAF (Sub-Resolution Assist Feature) with a line width of 40 nm may be provided in the transfer pattern (phase shift pattern) to be formed on the hard mask film 6. However, in this case, the cross-sectional aspect ratio of the resist pattern can be as low as 1:2.5, thereby suppressing damage and detachment of the resist pattern during development and rinsing of the resist film 7. It should be noted that 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.

[0229] The phase shift film 2, intermediate film 3, transmittance adjustment film 4, light shielding film 5, and hard mask film 6 are formed by sputtering, but any of DC sputtering, RF sputtering, and ion beam sputtering can also be used. When using a target with low conductivity, RF sputtering or ion beam sputtering is preferred. Considering the film formation rate, DC sputtering is more preferred. The resist film 7 is formed by spin coating.

[0230] In this way, refer to Figure 1 While the configuration of the mask blank 10 of this embodiment has been described, the mask blank is not limited to this configuration. For example, the mask blank may be configured without the intermediate film 3, hard mask film 6, or resist film 7. Alternatively, the mask blank may be configured with an etch stop film provided between the substrate 1 and the phase shift film 2. Examples of materials for the etch stop film in this case include materials containing aluminum, silicon, and oxygen, materials containing aluminum, hafnium, and oxygen, materials containing hafnium and oxygen, and materials containing chromium. These aspects also apply to the mask blank of the second embodiment described below.

[0231] [Phase-shift mask and its manufacturing]

[0232] In the phase shift mask 100 (see Figure 2 ), a phase shift film (phase shift pattern) 2a having a first pattern is provided on a translucent substrate 1, and a transmittance adjustment film (transmittance adjustment pattern) 4b having a second pattern is provided on the phase shift pattern 2a. Furthermore, an intermediate film (intermediate pattern) 3b having a second pattern is provided between the phase shift pattern 2a and the transmittance adjustment pattern 4b. Furthermore, a light-shielding film (light-shielding pattern) 5c having a third pattern is provided on the transmittance adjustment film 4b.

[0233] That is, the phase shift mask 100 of the first embodiment is characterized in that a phase shift pattern 2a is provided on a light-transmitting substrate 1, and an intermediate pattern 3b, a transmittance adjustment pattern 4b, and a light-shielding pattern 5c are provided on the phase shift pattern 2a. The phase shift pattern 2a causes a phase difference of 150 degrees or more and 210 degrees or less between the exposure light of the ArF excimer laser beam that has passed through the phase shift pattern 2a and the exposure light that has passed through the air only at a distance equal to the thickness of the phase shift pattern 2a. The refractive index of the transmittance adjustment pattern 4b at the wavelength of the exposure light is set to n. U , let the extinction coefficient at the wavelength of exposure light be k U , and set the thickness to d U When [nm], the following relationships of formula (1) and formula (2) are satisfied at the same time.

[0234] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0235] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0236] The specific configurations of the light-transmitting substrate 1 , the phase shift pattern 2 a , the intermediate pattern 3 b , the transmittance adjustment pattern 4 b , and the light-shielding pattern 5 c in the phase shift mask 100 are the same as those of the mask blank 10 .

[0237] Below, based on the schematic cross-sectional view of the main part Figure 3 and Figure 4 The manufacturing process shown in FIG. 1 will now be described as a method for manufacturing the phase shift mask 100 according to the first embodiment.

[0238] for Figure 1The resist film 7 formed by spin coating on the mask blank 10 shown in the figure is subjected to electron beam drawing of a first pattern to be formed on the phase shift film 2, and is further subjected to a predetermined process such as a development process, thereby forming a resist film (resist pattern) 7a having a first pattern (see FIG. Figure 3 (a)). The first pattern includes a phase shift pattern formed on the phase shift film 2 for exerting a phase shift effect, and a pattern for an alignment mark ( Figure 2 (opening on the left side of the

[0239] Next, the hard mask film 6 is dry-etched using a fluorine-based gas using the first resist pattern 7a as a mask to form a hard mask film (hard mask pattern) 6a having a first pattern (see FIG. Figure 3 (b)).

[0240] Next, the light shielding film 5 is dry-etched using a mixed gas of chlorine-based gas and oxygen-based gas using 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. Figure 3 (c)). Next, the first resist pattern 7a is removed and cleaned. Using the light shielding pattern 5a and the hard mask pattern 6a as masks, the transmittance adjustment film 4, the intermediate film 3, and the phase shift film 2 are dry-etched using a fluorine-based gas to form a transmittance adjustment film (transmittance adjustment 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' having a portion of the first pattern (see FIG. 1 ). Figure 3 (d)). This dry etching removes the hard mask pattern 6a. It should be noted that, during the dry etching of the phase shift film 2, in the process of forming the transmittance adjustment pattern 4b on the transmittance adjustment film 4 described later by dry etching, it is preferable to adjust the thickness of the portion of the remaining phase shift film 2a' so that the portion of the remaining phase shift film 2a' is also substantially removed at the same time when the formation of the transmittance adjustment pattern 4b is completed.

[0241] Next, a resist film is formed by spin coating. Then, an electron beam is used to draw a pattern to be formed on the transmittance adjustment film 4 on the resist film, and a predetermined process such as a development process is further performed to form a resist film (resist pattern) 8b having a second pattern (see Figure 4 (a)). Then, using the resist pattern 8b as a mask, the light shielding film 5a is dry-etched using a mixed gas of chlorine gas and oxygen to form a light shielding film (light shielding pattern 5b) having a second pattern (see Figure 4 (a)).

[0242] Then, the resist pattern 8b is removed, and cleaning is performed. The transmittance adjustment film 4 is dry-etched using a fluorine-based gas using the light-shielding pattern 5b as a mask to form a transmittance adjustment film (transmittance adjustment pattern) 4b having a second pattern (see FIG. Figure 4 (b)). At this time, the remaining portion of the phase shift film (phase shift pattern) 2a' having the first pattern is also removed, and the phase shift film (phase shift pattern) 2a' having the first pattern is formed (see Figure 4 (b)).

[0243] Then, using the light shielding pattern 5b and the transmittance adjustment pattern 4b as masks, 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. Figure 4 (c)). In this case, although the fluorine-based gas may dig into the exposed portion of the transparent substrate 1, as described above, the intermediate film 3 is formed of the same material as the transparent substrate 1, and thus the desired phase difference can be maintained between the exposed portion of the transparent substrate 1 and the exposed portion of the phase shift pattern 2a.

[0244] Then, a resist film is formed by spin coating. Then, the resist film is drawn with an electron beam in a pattern to be formed on the light shielding film 5, and a given process such as a development process is further performed to form a resist film (resist pattern) 9c having a third pattern (see Figure 4 (d)). Then, 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 to form a light shielding film (light shielding pattern) 5c having a third pattern (see Figure 4 (d)).

[0245] Then, the resist pattern 9c is removed and a cleaning process is performed. Figure 2 A phase-shift mask 100 is shown.

[0246] [Manufacturing of semiconductor devices]

[0247] The method for manufacturing a semiconductor device according to the first embodiment is characterized in that a transfer pattern is transferred by exposure to light onto a resist film on a semiconductor substrate using the phase-shift mask 100 according to the first embodiment or a phase-shift mask 100 manufactured using the mask blank 10 according to the first embodiment. Therefore, by exposing the resist film transferred onto the semiconductor device using the phase-shift mask 100 according to the first embodiment, a pattern can be formed on the resist film on the semiconductor device with accuracy that sufficiently meets design specifications.

[0248] <Second embodiment>

[0249] [Mask Blank and Its Manufacturing]

[0250] Figure 5 It is a cross-sectional view showing the structure of a mask blank 20 according to the second embodiment of the present invention. Figure 5 The mask blank 20 shown is similar to Figure 1 The mask blank 10 shown is different in that it has a three-layer structure comprising a first layer 12, a second layer 13, and a third layer 14, forming a phase shift film 15, and further includes a transmittance adjustment film 16 on the phase shift film 15. Hereinafter, descriptions of aspects common to the mask blank 10 of the first embodiment will be omitted as appropriate.

[0251] The phase shift film 15 in this embodiment is constructed such that the refractive indices n1, n2, and n3 of the first, second, and third layers 12, 13, and 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, second, and third layers 12, 13, and 14 satisfy the relationship k1>k2>k3. Furthermore, the film thicknesses d1, d2, and d3 of the first, second, and third layers 12, 13, and 14 satisfy the relationship d1>d2>d3.

[0252] The phase shift film 15 is composed of the first layer 12, the second layer 13, and the third layer 14 that satisfy this relationship. This allows for a phase shift film with a higher transmittance than the phase shift film 2 of the first embodiment. The configuration of the phase shift film 15 includes the phase shift film conditions set during the optical simulations B1, B2, and B3.

[0253] The phase shift film 15 can be made of the same material as the phase shift film 2 of the first embodiment. The total content of nitrogen and oxygen in the entire composition of the phase shift film 15 is preferably 40 atomic % or more, more preferably 50 atomic % or more.

[0254] The first layer 12 is preferably formed of a material containing silicon and nitrogen, the second layer 13 is preferably formed of a material containing silicon, oxygen, and nitrogen, and the third layer 14 as the uppermost layer is preferably formed of a material containing silicon and oxygen.

[0255] The transmittance adjusting film 16 is different from the transmittance adjusting film 4 in the first embodiment in that it is laminated on the phase shift film 15. Other conditions to be satisfied are the same as those of the transmittance adjusting film 4 in the first embodiment.

[0256] As described above, the mask blank 20 in this embodiment includes the transmittance adjustment film 16 on the phase shift film 15. The refractive index of the transmittance adjustment film 16 at the wavelength of the exposure light is n. U , let the extinction coefficient at the wavelength of exposure light be k U , and set the thickness to d U When [nm], the following relationships of formula (1) and formula (2) are satisfied at the same time.

[0257] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0258] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0259] As described above, if the transmittance adjustment film 16 satisfies equation (1), the condition that the increase in the phase difference of the exposure light transmitted through the laminated structure of the phase shift film 15 and the transmittance adjustment film 16 relative to the phase difference of the exposure light transmitted through the phase shift film 15 is 20 degrees or less can be satisfied. Furthermore, if the transmittance adjustment film 16 satisfies equation (2), 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 relative to the transmittance of the exposure light transmitted through the phase shift film 15 is 0.50 or less can be satisfied.

[0260] [Phase-shift mask and its manufacturing]

[0261] In the phase shift mask 200 (see Figure 6 ) comprises a phase shift film (phase shift pattern) 15a having a first pattern on a translucent substrate 1, and a transmittance adjustment film (transmittance adjustment pattern) 16b having a second pattern on the phase shift pattern 15a. Furthermore, the phase shift pattern 15a comprises a third layer 14a having a first pattern on the surface opposite to the translucent substrate 1. The third layer 14a having the first pattern is the topmost layer and contains silicon and oxygen. Furthermore, a light-shielding film (light-shielding pattern) 5c having a third pattern is provided on the transmittance adjustment pattern 16b.

[0262] That is, the phase shift mask 200 of the second embodiment is characterized in that a phase shift pattern 15a is provided on a light-transmitting substrate 1, and a transmittance adjustment pattern 16b and a light-shielding pattern 5c are provided on the phase shift pattern 15a. The phase shift pattern 15a causes a phase difference of 150 degrees or more and 210 degrees or less between the exposure light of the ArF excimer laser beam that has passed through the phase shift pattern 15a and the exposure light that has passed through the air at a distance equal to the thickness of the phase shift pattern 15a. The refractive index of the transmittance adjustment pattern 16b at the wavelength of the exposure light is set to n. U , let the extinction coefficient at the wavelength of exposure light be k U, and set the thickness to d U When [nm], the following relationships of formula (1) and formula (2) are satisfied at the same time.

[0263] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0264] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0265] The specific configurations of the light-transmitting substrate 1 , the phase shift pattern 15 a , the transmittance adjustment pattern 16 b , and the light-shielding pattern 5 c in the phase shift mask 200 are the same as those in the mask blank 20 .

[0266] Below, based on the schematic cross-sectional view of the main part Figure 7 and Figure 8 The manufacturing process shown in FIG. 1 will now be described as a method for manufacturing the phase shift mask 200 according to the second embodiment.

[0267] for Figure 5 The resist film 7 formed by spin coating on the mask blank 20 shown in FIG. 1 is subjected to electron beam drawing of a first pattern to be formed on the phase shift film 15 and further subjected to a predetermined process such as a development process to form a resist film (resist pattern) 7a having a first pattern (see FIG. 1 ). Figure 7 (a)). The first pattern includes a phase shift pattern formed on the phase shift film 15 for exerting a phase shift effect, and a pattern for an alignment mark ( Figure 6 (opening on the left side of the

[0268] Next, the hard mask film 6 is dry-etched using a fluorine-based gas using the first resist pattern 7a as a mask to form a hard mask film (hard mask pattern) 6a having a first pattern (see FIG. Figure 7 (b)).

[0269] Next, the light shielding film 5 is dry-etched using a mixed gas of chlorine-based gas and oxygen-based gas using 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. Figure 7(c)). Next, the first resist pattern 7a is removed and cleaned. Using the light shielding pattern 5a and the hard mask pattern 6a as masks, the transmittance adjustment film 16 and the phase shift film 15 are dry-etched using a fluorine-based gas to form a transmittance adjustment film (transmittance adjustment pattern) 16a having a first pattern and a phase shift film (phase shift pattern) 15a' having a portion of the first pattern (see FIG. 1). Figure 7 (d)). The phase shift pattern 15a' is composed of a first layer 12a' partially having a 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. It should be noted that, in the dry etching of the phase shift film 15, in the process of forming the transmittance adjustment pattern 16b on the transmittance adjustment film 16 described later by dry etching, it is preferable to adjust the thickness of the remaining phase shift film 15a' (first layer 12a') so that the remaining phase shift film 15a' (first layer 12a') is also substantially removed at the same time when the transmittance adjustment pattern 16b is formed.

[0270] Next, a resist film is formed by spin coating. Then, the pattern to be formed on the transmittance adjustment film 16 is drawn on the resist film using an electron beam, and a predetermined process such as a development process is further performed to form a resist film (resist pattern) 8b having a second pattern (see Figure 8 (a)). Then, using the resist pattern 8b as a mask, the light shielding film 5a is dry-etched using a mixed gas of chlorine gas and oxygen to form a light shielding film (light shielding pattern 5b) having a second pattern (see Figure 8 (a)).

[0271] Then, the resist pattern 8b is removed, and cleaning is performed. The transmittance adjustment film 16 is dry-etched using a fluorine-based gas using the light-shielding pattern 5b as a mask to form a transmittance adjustment film (transmittance adjustment pattern) 16b having a second pattern (see FIG. Figure 8 (b)). At this time, the remaining portion of the phase shift film (phase shift pattern) 15a' having the first pattern is also removed, and the phase shift film (phase shift pattern) 15a having the first pattern is formed (see Figure 8 (b)).

[0272] Then, a resist film is formed by spin coating. Then, the resist film is drawn with an electron beam in a pattern to be formed on the light shielding film 5, and a given process such as a development process is further performed to form a resist film (resist pattern) 9c having a third pattern (see Figure 8 (c)). Then, 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 to form a light shielding film (light shielding pattern) 5c having a third pattern (see Figure 8(c)).

[0273] Then, after the resist pattern 9c is removed, a cleaning process is performed. Figure 6 Phase shift mask 200 is shown.

[0274] [Manufacturing of semiconductor devices]

[0275] The method for manufacturing a semiconductor device according to the second embodiment is characterized in that a transfer pattern is transferred by exposure to light onto a resist film on a semiconductor substrate using the phase-shift mask 200 according to the second embodiment or a phase-shift mask 200 manufactured using the mask blank 20 according to the second embodiment. Therefore, by exposing the resist film transferred onto the semiconductor device using the phase-shift mask 200 according to the second embodiment, a pattern can be formed on the resist film on the semiconductor device with accuracy that sufficiently meets design specifications.

[0276] <Third embodiment>

[0277] [Mask Blank and Its Manufacturing]

[0278] Figure 13 It is a cross-sectional view showing the structure of a mask blank 30 according to a third embodiment of the present invention. Figure 13 The mask blank 30 shown is similar to Figure 1 The mask blank 10 shown is different in that a transmittance adjustment film 41 is provided directly on the phase shift film 2, and an etching stopper film 31 is arranged between the transmittance adjustment film 41 and the light shielding film 5. Hereinafter, descriptions of aspects common to the mask blank 10 of the first embodiment will be appropriately omitted.

[0279] The transmittance adjustment film 41 in this embodiment is formed of a material containing chromium. The transmittance adjustment film 41 has sufficient etching selectivity with 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 one or more elements selected from oxygen, nitrogen, carbon, boron, and fluorine in chromium. Alternatively, the transmittance adjustment film 41 may use a chromium-based material used for the light shielding film 5. The transmittance adjustment film 41 is designed to have a refractive index n of 0.001 at the wavelength of the exposure light. U , extinction coefficient k at the wavelength of exposure light U , thickness d U [nm] satisfies the relationship of the above formula (1) and formula (2) at the same time.

[0280] In the case where the light-shielding film 5 is formed of the above-mentioned chromium-containing material, the etching stopper film 31 in this embodiment 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 formed of a material containing silicon and oxygen. On the other hand, the etching stopper film 31 can also be formed of a material containing tantalum and oxygen. The thickness of the etching stopper film 31 is preferably greater than 1 nm, more preferably greater than 2 nm. In addition, the thickness of the etching stopper film 31 is preferably less than 10 nm, more preferably less than 5 nm. It should be noted that in this 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.

[0281] As described above, the mask blank 30 in this embodiment includes the transmittance adjustment film 41 on the phase shift film 2. The refractive index of the transmittance adjustment film 41 at the wavelength of the exposure light is n. U , let the extinction coefficient at the wavelength of exposure light be k U , and set the thickness to d U When [nm], the following relationships of formula (1) and formula (2) are satisfied at the same time.

[0282] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0283] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0284] As described above, if the transmittance adjustment film 41 satisfies equation (1), the condition that the increase in the phase difference of the exposure light transmitted through the stacked structure of the phase shift film 2 and the transmittance adjustment film 41 relative to the phase difference of the exposure light transmitted through the phase shift film 2 is 20 degrees or less can be satisfied. Furthermore, if the transmittance adjustment film 41 satisfies equation (2), the condition that the ratio of the transmittance of the exposure light transmitted through the stacked structure of the phase shift film 2 and the transmittance adjustment film 41 relative to the transmittance of the exposure light transmitted through the phase shift film 2 is 0.50 or less can be satisfied.

[0285] [Phase-shift mask and its manufacturing]

[0286] In the phase shift mask 300 (see Figure 14), a phase shift film (phase shift pattern) 2a having a first pattern is provided on a translucent substrate 1, and a transmittance adjustment film (transmittance adjustment pattern) 41b having a second pattern is provided on the phase shift pattern 2a. Furthermore, an etching stopper film (etching stop pattern) 31b having a second pattern is provided on the transmittance adjustment pattern 41b. Furthermore, a light shielding film (light shielding pattern) 5c having a third pattern is provided on the etching stopper film 31b.

[0287] That is, the phase shift mask 300 of the third embodiment is characterized in that a phase shift pattern 2a is provided on a light-transmitting substrate 1, and a transmittance adjustment pattern 41b, an etching stop pattern 31b, and a light-shielding pattern 5c are provided on the phase shift pattern 2a. The phase shift pattern 2a causes 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 pattern 2a and the exposure light that has passed through the air only at a distance equal to the thickness of the phase shift pattern 2a. The refractive index of the transmittance adjustment pattern 41b at the wavelength of the exposure light is set to n U , let the extinction coefficient at the wavelength of exposure light be k U , and set the thickness to d U When [nm], the following relationships of formula (1) and formula (2) are satisfied at the same time.

[0288] Formula (1)d U ≤-17.63×n U 3 +142.0×n U 2 -364.9×n U +315.8

[0289] Formula (2)d U ≥-2.805×k U 3 +19.48×k U 2 -43.58×k U +38.11

[0290] The specific configurations of the light-transmitting substrate 1 , the phase shift pattern 2 a , the transmittance adjustment pattern 41 b , the etching stop pattern 31 b , and the light-shielding pattern 5 c in the phase shift mask 300 are the same as those of the mask blank 30 .

[0291] Below, based on the schematic cross-sectional view of the main part Figure 15 and Figure 16 The manufacturing process shown in FIG. 1 will now be described as a method for manufacturing the phase shift mask 300 according to the third embodiment.

[0292] for Figure 13The resist film 7 formed by spin coating on the mask blank 30 shown in the figure is subjected to electron beam drawing of a first pattern to be formed on the phase shift film 2, and is further subjected to a predetermined process such as a development process, thereby forming a resist film (resist pattern) 7a having a first pattern (see FIG. Figure 15 (a) The first pattern includes a phase shift pattern formed in the phase shift film 2 for exerting a phase shift effect.

[0293] Next, the light shielding film 5 is dry-etched using a mixed gas of chlorine gas and oxygen using the first resist pattern 7a as a mask, thereby forming a light shielding film (light shielding pattern) 5a having a first pattern (see FIG. Figure 15 (b)).

[0294] Next, the etching stopper film 31 is dry-etched using a fluorine-based gas using the first resist pattern 7a and the light-shielding pattern 5a as masks to form an etching stopper film (etching stopper pattern) 31a having a first pattern (see FIG. Figure 15 (c)). Next, the first resist pattern 7a is removed and a cleaning process is performed. Next, a resist film is formed by spin coating. Then, the pattern to be formed on the etching stop film 31 and the transmittance adjustment film 41 is drawn on the resist film using an electron beam, and a predetermined process such as a development process is further performed to form a resist film (resist pattern) 8b having a second pattern (see Figure 15 (d)).

[0295] Next, the light shielding film 5a is dry-etched using a mixed gas of chlorine gas and oxygen using the resist pattern 8b as a mask to form a light shielding film (light shielding pattern 5b) having a second pattern (see FIG. Figure 16 (a)). At this time, the transmittance adjustment film 41 is also dry-etched using the etching stop pattern 31a as a mask, forming a transmittance adjustment film (transmittance adjustment 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 using the transmittance adjustment pattern 41a as a mask, forming a phase shift film (phase shift pattern) 2a having a first pattern (see Figure 16 (b) At this time, the etching stopper pattern 31a is also dry-etched using the light-shielding pattern 5b as a mask, thereby forming an etching stopper film (etching stopper pattern) 31b having a second pattern.

[0296] Next, the second resist pattern 8b is removed and a cleaning process is performed. Next, a resist film is formed by spin coating. Then, the pattern to be formed on the light shielding film 5 is drawn on the resist film using an electron beam, and a predetermined process such as a development process is further performed to form a resist film (resist pattern) 9c having a third pattern (see Figure 16(c)). Next, the light shielding film 5b is dry-etched using a mixed gas of chlorine gas and oxygen using the resist pattern 9c as a mask to form a light shielding film (light shielding pattern 5c) having a third pattern (see Figure 16 (d)). At this time, the transmittance adjustment pattern 41a is also dry-etched using the etching stop pattern 31b as a mask to form a transmittance adjustment film (transmittance adjustment pattern) 41b having a second pattern. Then, after removing the resist pattern 9c, a cleaning step is performed. In this way, a Figure 14 Phase shift mask 300 is shown.

[0297] [Manufacturing of semiconductor devices]

[0298] The method for manufacturing a semiconductor device according to the third embodiment is characterized in that a transfer pattern is transferred by exposure to light onto a resist film on a semiconductor substrate using the phase-shift mask 300 according to the third embodiment or a phase-shift mask 300 manufactured using the mask blank 30 according to the third embodiment. Therefore, by exposing the resist film transferred onto the semiconductor device using the phase-shift mask 300 according to the third embodiment, a pattern can be formed on the resist film on the semiconductor device with accuracy that fully meets design specifications.

[0299] Example

[0300] Hereinafter, embodiments of the present invention will be described in more detail using examples.

[0301] (Example 1)

[0302] [Mask Blank Manufacturing]

[0303] A translucent substrate 1 made of synthetic quartz glass was prepared, with a main surface dimension of approximately 152 mm x 152 mm and a thickness of approximately 6.35 mm. The end faces and main surface of this translucent substrate 1 were polished to a predetermined surface roughness, followed by a predetermined cleaning and drying process. The optical properties of this translucent substrate 1 were measured, revealing a refractive index n of 1.556 and an extinction coefficient k of 0.00 at the wavelength of ArF exposure light.

[0304] Next, a translucent substrate 1 was placed in a film-forming sputtering apparatus. Using a silicon (Si) target, reactive sputtering with a mixed gas of argon (Ar) and nitrogen (N2) was performed to form a 60.4 nm thick phase shift film 2 containing silicon and nitrogen (SiN film, Si:N = 34.8 atomic %:65.2 atomic %) in contact with the surface of the translucent substrate 1. Next, using a silicon (Si) target, reactive sputtering with a mixed gas of argon (Ar) and oxygen (O2) was performed to form a 3.0 nm thick intermediate film 3 containing silicon and oxygen (SiO2 film) on the phase shift film 2. Finally, reactive sputtering with a mixed gas of argon (Ar) and nitrogen (N2) was performed to form a 12.0 nm thick transmittance adjustment film 4 containing silicon and nitrogen.

[0305] Using a phase shift measurement device (MPM193 manufactured by Laser Tech), a phase shift film was similarly formed on another translucent substrate, and the transmittance and retardation for light with a wavelength of 193 nm were measured. The results showed a transmittance of 18.6% and a retardation of 180.0 degrees. Separately, a phase shift film and a transmittance adjustment film were similarly formed on another translucent substrate, and the transmittance and retardation for light with a wavelength of 193 nm were measured. The results showed a transmittance of 6.1% and a retardation of 180.0 degrees. It should be noted that the interlayer film 3 had a relatively thin thickness of 3 nm and had a high transmittance similar to that of the translucent substrate. Therefore, the effect of the presence of the interlayer film 3 on the transmittance and retardation was negligible.

[0306] Furthermore, the optical properties of the phase shift film 2, the intermediate film 3, and the transmittance adjustment film 4 were measured. The results were as follows: the refractive index n of the phase shift film 2 was 2.61, and the extinction coefficient k was 0.36; the refractive index n of the intermediate film 3 was 1.56, and the extinction coefficient k was 0.00; the refractive index n of the transmittance adjustment film 4 was 0. U is 1.52, extinction coefficient k U It is 2.09.

[0307] The thickness d of the transmittance adjustment film 4 is U [nm], refractive index n U and extinction coefficient k U The value of satisfies any of the relationships in formula (1), formula (2), and formula (3).

[0308] Next, a translucent substrate 1, on which a phase shift film 2, an intermediate film 3, and a transmittance adjustment film 4 were formed, was placed in a film-forming sputtering apparatus. Using a chromium (Cr) target, reactive sputtering with a mixed gas of argon (Ar), carbon dioxide (CO2), and helium (He) was performed to form a 44 nm thick light-shielding film 5 containing CrOC on the transmittance adjustment film 4. The optical density (OD) of the laminated structure of the phase shift film 2, intermediate film 3, transmittance adjustment film 4, and light-shielding film 5 for light with a wavelength of 193 nm was measured and found to be 3.0 or greater.

[0309] Next, a 12 nm thick hard mask film 6 containing silicon, nitrogen, and oxygen was formed 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 a sputtering gas on the light-shielding film 5. The surface of the hard mask film 6 was then treated with HMDS. Next, an 80 nm thick resist film 7 made of a chemically amplified resist for electron beam lithography was formed in contact with the surface of the hard mask film 6 by spin coating.

[0310] Through the above-described procedure, a mask blank 10 having a structure in which the phase shift film 2 , the intermediate film 3 , the transmittance adjustment film 4 , the light shielding film 5 , the hard mask film 6 , and the resist film 7 are stacked on the light-transmitting substrate 1 is manufactured.

[0311] [Manufacturing of Phase-Shift Mask]

[0312] Next, the phase shift mask 100 of Example 1 was manufactured by using the mask blank 10 of Example 1 according to the procedure of the method for manufacturing the phase shift mask described in the first embodiment.

[0313] The halftone phase shift mask 100 of Example 1 was placed on the mask stage of an exposure apparatus using ArF excimer laser light. The ArF exposure light was irradiated from the light-transmitting substrate 1 side of the phase shift mask 100, and a pattern was transferred by exposure to the resist film on the semiconductor device. The transferred pattern included a relatively fine pattern and a relatively sparse pattern.

[0314] The resist film after exposure transfer was subjected to a predetermined treatment to form a resist pattern, which was then observed using a SEM (Scanning Electron Microscope). The results revealed that a desired transfer pattern was formed for any pattern. Based on these results, it was believed that the resist pattern could be used as a mask to form a circuit pattern on a semiconductor device with high precision.

[0315] (Example 2)

[0316] [Mask Blank Manufacturing]

[0317] 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 comprised a three-layer structure consisting of a stacked first layer 12, a second layer 13, and a third layer 14, and a transmittance adjustment film 16 was provided on the phase shift film 15. Specifically, in the mask blank 20 of Example 2, the first layer 12a of the phase shift film 15 was formed with a thickness of 41 nm using a material containing silicon and nitrogen, having a refractive index n of 2.61 and an extinction coefficient k of 0.36 at a wavelength of 193 nm. The second layer 13a was formed with a thickness of 24 nm using a material containing silicon, oxygen, and nitrogen, having a refractive index n of 2.18 and an extinction coefficient k of 0.12 at a wavelength of 193 nm. The third layer 14a was formed with a thickness of 4 nm using a material containing silicon and oxygen, having a refractive index n of 1.56 and an extinction coefficient k of 0.00 at a wavelength of 193 nm. The transmittance adjustment film 16 contains silicon and nitrogen and has a refractive index n under a wavelength of 193 nm. U is 1.52, extinction coefficient k U The material with a thickness of 2.09 nm is 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.

[0318] The thickness d of the transmittance adjustment film 16 is U [nm], refractive index n U and extinction coefficient k U The value of also satisfies any of the relationships in formula (1), formula (2), and formula (3).

[0319] A phase shift film was similarly formed on another translucent substrate, and the transmittance and retardation for light with a wavelength of 193 nm were measured using a phase shift measurement device (MPM193 manufactured by Laser Tech). The results showed a transmittance of 28.0% and a retardation of 180.0 degrees. Separately, a phase shift film and a transmittance adjustment film were similarly formed on another translucent substrate, and the transmittance and retardation for light with a wavelength of 193 nm were measured. The results showed a transmittance of 6.0% and a retardation of 178.0 degrees.

[0320] [Manufacturing of Phase-Shift Mask]

[0321] Next, using the mask blank 20 of Example 2, the phase shift mask 200 of Example 2 was manufactured according to the procedure of the phase shift mask manufacturing method described in the second embodiment.

[0322] The halftone phase shift mask 200 of Example 2 was placed on the mask stage of an exposure apparatus using ArF excimer laser light. The ArF exposure light was irradiated from the light-transmitting substrate 1 side of the phase shift mask 200, and a pattern was transferred by exposure to the resist film on the semiconductor device. The transferred pattern included a relatively fine pattern and a relatively sparse pattern.

[0323] The resist film after exposure transfer was subjected to a predetermined treatment to form a resist pattern, which was then observed using a SEM (Scanning Electron Microscope). The results revealed that a desired transfer pattern was formed for any pattern. Based on these results, it was believed that the resist pattern could be used as a mask to form a circuit pattern on a semiconductor device with high precision.

[0324] (Example 3)

[0325] [Mask Blank Manufacturing]

[0326] A translucent substrate 1 made of synthetic quartz glass was prepared, with a main surface dimension of approximately 152 mm x 152 mm and a thickness of approximately 6.35 mm. The end faces and main surface of this translucent substrate 1 were polished to a predetermined surface roughness, followed by a predetermined cleaning and drying process. The optical properties of this translucent substrate 1 were measured, revealing a refractive index n of 1.556 and an extinction coefficient k of 0.00 at the wavelength of ArF exposure light.

[0327] Next, a translucent substrate 1 was placed in a film-forming sputtering apparatus. Using a silicon (Si) target, reactive sputtering with a mixed gas of argon (Ar) and nitrogen (N2) was performed to form a 60 nm thick phase shift film 2 containing silicon and nitrogen (SiN film, Si:N = 34.8 atomic %:65.2 atomic %) in contact with the surface of the translucent substrate 1. Next, using a chromium (Cr) target, reactive sputtering with a mixed gas of argon (Ar), carbon dioxide (CO2), and helium (He) was performed to form an 11 nm thick transmittance adjustment film 41 containing CrOC on the phase shift film 2. Next, using a silicon (Si) target, reactive sputtering with a mixed gas of argon (Ar) and oxygen (O2) was performed to form a 3.0 nm thick etching stopper film 31 containing silicon and oxygen (SiO2 film) on the transmittance adjustment film 41.

[0328] Using a phase shift measurement device (MPM193 manufactured by Laser Tech), a phase shift film was similarly formed on another translucent substrate, and the transmittance and phase difference for light with a wavelength of 193 nm were measured. The results showed a transmittance of 18.6% and a phase difference of 180.0 degrees. Separately, a phase shift film and a transmittance adjustment film were similarly formed on another translucent substrate, and the transmittance and phase difference for light with a wavelength of 193 nm were measured. The results showed a transmittance of 6.0% and a phase difference of 191.0 degrees. It should be noted that the etching stop film 31 has a relatively thin film thickness of 3 nm and has the same high transmittance as the translucent substrate. Therefore, the effect of the presence or absence of the etching stop film 31 on the transmittance and phase difference can be ignored.

[0329] Furthermore, the optical properties of the phase shift film 2, the transmittance adjustment film 41, and the etching stopper film 31 were measured. The results showed that the refractive index n of the phase shift film 2 was 2.61, the extinction coefficient k was 0.36, and the refractive index n of the transmittance adjustment film 41 was 0. U The extinction coefficient k is 1.82. U The refractive index n of the etching stopper film 31 is 1.56, and the extinction coefficient k is 0.00.

[0330] The thickness d of the transmittance adjustment film 41 is U [nm], refractive index n U and extinction coefficient k U The value of satisfies any of the relationships in formula (1), formula (2), and formula (3).

[0331] Next, a three-layered light-shielding film 5 was formed on the etching stop film 31 with a thickness of 78 nm. Specifically, a translucent substrate 1 on which a phase shift film 2, a transmittance adjustment film 41, and an etching stop film 31 were formed was set in a film-forming sputtering apparatus. A chromium (Cr) target was used to reactively sputter a mixed gas of argon (Ar), nitrogen (N2), carbon dioxide (CO2), and helium (He) to form a first layer containing CrOCN with a thickness of 31 nm. Next, a chromium (Cr) target was used to reactively sputter a mixed gas of argon (Ar), nitrogen (N2), carbon dioxide (CO2), and helium (He) to form a second layer containing CrOCN with a thickness of 41 nm. Furthermore, a chromium (Cr) target was used to reactively sputter a mixed gas of argon (Ar), nitrogen (N2), and helium (He) to form a third layer containing CrN with a thickness of 6 nm.

[0332] The optical density (OD) of the laminated structure of the phase shift film 2, transmittance adjustment film 41, etching stop film 31, and light shielding film 5 for light with a wavelength of 193 nm was measured and found to be 3.2 or greater. Subsequently, a resist film 7 composed of a chemically amplified resist for electron beam lithography was formed in contact with the surface of the light shielding film 5 by spin coating to a thickness of 80 nm.

[0333] Through the above-described procedures, the mask blank 30 having a structure in which the phase shift film 2 , the transmittance adjustment film 41 , the etching stopper film 31 , the light shielding film 5 , and the resist film 7 are stacked on the light-transmitting substrate 1 is manufactured.

[0334] [Manufacturing of Phase-Shift Mask]

[0335] Next, using the mask blank 30 of Example 3, the phase shift mask 300 of Example 3 was manufactured according to the procedure of the method for manufacturing a phase shift mask described in the third embodiment.

[0336] The halftone phase shift mask 300 of Example 3 was placed on the mask stage of an exposure apparatus using ArF excimer laser light. The ArF exposure light was irradiated from the light-transmitting substrate 1 side of the phase shift mask 300, and a pattern was transferred by exposure to the resist film on the semiconductor device. The transferred pattern included a relatively fine pattern and a relatively sparse pattern.

[0337] The resist film after exposure transfer was subjected to a predetermined treatment to form a resist pattern, which was then observed using a SEM (Scanning Electron Microscope). The results revealed that a desired transfer pattern was formed for any pattern. Based on these results, it was believed that the resist pattern could be used as a mask to form a circuit pattern on a semiconductor device with high precision.

Claims

1. A mask blank comprising a phase shift film on a light-transmitting substrate, A transmittance adjustment film is provided on the phase shift film, The phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between the exposure light of the ArF excimer laser after passing through the phase shift film and the exposure light after passing through the air only at a distance equal to the thickness of the phase shift film. The refractive index of the transmittance adjustment film at the wavelength of the exposure light is set to n U , the extinction coefficient at the wavelength of the exposure light is set to k U , and set the thickness to d U [nm], the following relationships (1) and (2) are satisfied simultaneously: 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, The refractive index n of the transmittance adjusting film U is 1.2 or more and 3.0 or less, The extinction coefficient k of the transmittance adjusting film U It is 1.5 or more and 3.0 or less.

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

3. The mask blank according to claim 1, wherein The extinction coefficient k of the transmittance adjusting film U With the thickness d U [nm] satisfies the following relationship (3), Formula (3) d U ≤8.646×k U 2 -38.42×k U +61.

89.

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

5. The mask blank according to claim 1, wherein An intermediate film containing silicon and oxygen is provided between the phase shift film and the transmittance adjustment film. The mask blank according to claim 1 , wherein: The phase shift film includes an uppermost layer containing silicon and oxygen on a surface side opposite to the light-transmitting substrate side.

7. The mask blank according to any one of claims 1 to 6, wherein A light-shielding film is provided on the transmittance adjustment film.

8. A phase shift mask comprising a phase shift film having a first pattern on a light-transmitting substrate, A transmittance adjustment film having a second pattern is provided on the phase shift film. The phase shift film generates a phase difference of 150 degrees or more and 210 degrees or less between the exposure light of the ArF excimer laser beam that has passed through the phase shift film and the exposure light that has passed through the air only at a distance equal to the thickness of the phase shift film. The refractive index of the transmittance adjustment film at the wavelength of the exposure light is set to n U , the extinction coefficient at the wavelength of the exposure light is set to k U , and set the thickness to d U [nm], the following relationships (1) and (2) are satisfied simultaneously: 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, The refractive index n of the transmittance adjusting film U is 1.2 or more and 3.0 or less, The extinction coefficient k of the transmittance adjusting film U It is 1.5 or more and 3.0 or less.

9. The phase-shift mask according to claim 8, wherein: The phase shift film transmits the exposure light at a transmittance of 12% or more.

10. The phase-shift mask according to claim 8, wherein The extinction coefficient k of the transmittance adjusting film U With the thickness d U [nm] satisfies the following relationship (3), Formula (3) d U ≤8.646×k U 2 -38.42×k U +61.

89. The phase-shift mask according to claim 8 , wherein: The transmittance adjusting film contains silicon and nitrogen.

12. The phase-shift mask according to claim 8, wherein An intermediate film having the second pattern is provided between the phase shift film and the transmittance adjustment film, and the intermediate film contains silicon and oxygen.

13. The phase-shift mask according to claim 8, wherein The phase shift film includes an uppermost layer containing silicon and oxygen on a surface side opposite to the light-transmitting substrate side.

14. The phase-shift mask according to any one of claims 8 to 13, wherein: A light-shielding film having a third pattern is provided on the transmittance adjustment film.

15. A method for manufacturing a phase-shift mask using the mask blank according to claim 7, the method comprising: forming a first pattern on the light-shielding film by dry etching; forming a first pattern on 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 on the light-shielding film by dry etching; forming a second pattern on the transmittance adjustment film by dry etching using the light shielding film having the second pattern as a mask; and A step of forming a third pattern on the light shielding film by dry etching.

16. A method for manufacturing a semiconductor device, the method comprising the following steps: Using the phase shift mask according to claim 14, a transfer pattern is transferred by exposure to a resist film on a semiconductor substrate.

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