Phase-shift mask blank, phase-shift mask, and manufacturing method

Abstract

To suppress occurrence of surface damage on a transparent substrate and to allow recycling without requiring a polishing step.SOLUTION: A phase-shift mask blank 10B has a mask layer that serves as a phase-shift mask 10, the phase-shift mask blank comprising a phase-shift layer 12 laminated on a transparent substrate 11 and a light-shielding layer 13 laminated on the phase-shift layer, wherein the phase-shift layer comprises a lower phase-shift layer 12a laminated on the transparent substrate and an upper phase-shift layer 12b laminated on the lower phase-shift layer, the lower phase-shift layer and the light-shielding layer being etchable with the same etching solution, and the upper phase-shift layer being etchable with an etching solution different from that for the lower phase-shift layer and the light-shielding layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a phase shift mask blank, a phase shift mask, and a technique suitable for use in a manufacturing method thereof. [Background technology]

[0002] 2. Description of the Related Art In the manufacture of FPDs (flat panel displays) such as liquid crystal displays and organic EL displays, or in the manufacture of semiconductor devices, photomasks are used in a photoresist process. In this case, a mask blank having a mask layer made of a chromium compound formed on a quartz substrate may be used as the photomask.

[0003] In recent years, the trend toward higher resolution has progressed significantly, and photomasks have also become increasingly miniaturized. This has led to a growing need for edge-enhancing phase-shift masks in addition to conventional masks that use light-shielding films. Conventionally, a phase shift mask may have a phase shift layer formed of a silicide film as a mask layer on a quartz substrate, and a light-shielding layer (binary layer) formed of a metal film such as a chromium film on top of that.

[0004] When a phase shift mask is formed with a light-shielding layer made of chromium and a phase shift layer made of metal silicide, wet etching with a predetermined etching solution (etchant) is used to form the desired pattern, and a cleaning solution such as an alkali is used for cleaning. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5605917 Summary of the Invention [Problem to be solved by the invention]

[0006] The tolerance range for the optical properties of each layer in a photomask is extremely narrow. This limits the degree of freedom in the optical density and film thickness of each layer. Furthermore, to accommodate narrower widths, stricter cross-sectional perpendicularity is required. Furthermore, because even slight changes in film thickness are critical for each layer of the mask layer, high chemical resistance to etching or cleaning solutions is also required. However, layers with high chemical resistance require longer etching times, which can adversely affect exposed areas other than the target area. For example, this can cause surface roughness on the glass substrate, unexpected changes in film thickness, and poor cross-sectional shape due to poor etching. For this reason, there is also a demand for shortening the etching time.

[0007] Phase-shift mask blanks for FPDs have a problem in that the wet etching time of the phase-shift film is long when a silicide film containing molybdenum and silicon is used as the phase-shift film. Typically, a solution containing hydrofluoric acid is used as the wet etching solution for the silicide film. This poses a problem in that the quartz substrate is etched during the wet etching of the silicide film, changing the phase-shift characteristics of the silicide film. If the wet etching time of the silicide film is shortened to avoid this problem, the required phase-shift characteristics may not be obtained.

[0008] The technology described in Patent Document 1 solves the problem of photoresist alignment. However, this technology uses an etching solution containing hydrofluoric acid to etch the silicon-containing underlayer film 20. This inevitably damages the surface of the transparent substrate. In addition to the above problems, this damage can cause defects and scratches to become apparent on the surface of the transparent substrate, and can leave patterns that appear as if the surface of the transparent substrate has been dug.

[0009] Furthermore, damage caused by etching solutions containing hydrofluoric acid can cause defects and scratches on the surface of the transparent substrate, and if patterns resembling hollows remain on the surface of the transparent substrate, recycling the substrate becomes difficult unless the substrate is re-polished. This re-polishing process places a heavy burden on the environment and is time-consuming, so there is a need to make it possible to recycle transparent substrates without this process.

[0010] The present invention has been made in view of the above circumstances, and aims to achieve the following objects. 1. To reduce damage to the transparent substrate surface while maintaining phase shift characteristics. 2. To make it possible to manufacture a phase shift mask without causing any change in the phase shift characteristics. 3. Transparent substrates can be recycled without undergoing a re-polishing process. [Means for solving the problem]

[0011] (1) A phase shift mask blank according to one aspect of the present invention, A phase shift mask blank having a mask layer that serves as a phase shift mask, a phase shift layer laminated on a transparent substrate; a light-shielding layer laminated on the phase shift layer; and The phase shift layer comprises: a lower phase shift layer laminated on the transparent substrate; an upper phase shift layer stacked on the lower phase shift layer; and the lower phase shift layer and the light-shielding layer can be etched with the same etchant; the upper phase shift layer is etchable with an etchant different from that of the lower phase shift layer and the light-shielding layer; This solved the above problem. (2) The phase shift mask blank of the present invention, in the above (1), In a state in which a first light-shielding pattern formed by etching from the light-shielding layer and an upper phase shift pattern formed by etching from the upper phase shift layer are formed to have the same width, a lower phase shift pattern having the same width as the upper phase shift pattern is formed from the lower phase shift layer to form a transparent region of the phase shift mask, a second light-shielding pattern formed by side etching from the first light-shielding pattern has a width narrower than that of the upper phase shift pattern, and can form a phase shift region of the phase shift mask; It is possible. (3) The phase shift mask blank of the present invention, in the above (2), the thickness of the lower phase shift layer is smaller than the thickness of the light-shielding layer; It is possible. (4) The phase shift mask blank of the present invention, in the above (3), a thickness of the lower phase shift layer is smaller than a side etching amount of the first light-shielding pattern; It is possible. (5) The phase shift mask blank of the present invention, in the above (4), The width of the phase shift region is 4.0 to 500 times the thickness of the lower phase shift layer. It is possible. (6) The phase shift mask blank of the present invention, in the above (5), an etching rate of the lower phase shift layer is 1 / 11 to 1 / 2 times the side etching rate of the light-shielding layer; It is possible. (7) The phase shift mask blank of the present invention is, in the above (6), the light-shielding layer contains chromium, the lower phase shift layer contains one or more selected from chromium, nickel, molybdenum, niobium, and titanium; the upper phase shift layer contains silicon and has etching selectivity with respect to the lower phase shift layer and the light-shielding layer; It is possible. (8) A phase shift mask according to another aspect of the present invention comprises: A phase shift mask manufactured from the phase shift mask blank according to any one of (2) to (6) above, The surface roughness of the transparent substrate in the transmission region is in the range of Ra 0.14 nm to Ra 2.5 nm. It is possible. (9) Another aspect of the present invention is a method for manufacturing a phase shift mask, A method for manufacturing a phase shift mask according to (8) above, preparing a phase shift mask blank in which the lower phase shift layer, the upper phase shift layer, and the light-shielding layer formed on the transparent substrate are laminated; a first etching step of forming the first light-shielding pattern from the light-shielding layer by wet etching using a first etching solution, using a resist pattern formed by laminating on the light-shielding layer as a mask; a second etching step of forming the upper phase shift pattern from the upper phase shift layer by wet etching using at least the etched first light-shielding pattern as a mask and a second etching liquid different from the first etching liquid; a third etching step of forming a second light-shielding pattern from the first light-shielding pattern by side etching using a third etching solution that is the same as the first etching solution, using at least the resist pattern as a mask, and simultaneously forming a lower phase shift pattern from the lower phase shift layer by wet etching; and the resist pattern is not peeled off in the first etching step, the second etching step, and the third etching step; It is possible. (10) A method for manufacturing a phase shift mask according to the present invention comprises the steps of: In the second etching step, the first light-shielding pattern and the upper phase shift pattern are formed to have the same width; In the third etching step, the upper phase shift pattern and the lower phase shift pattern are formed to have the same width to form the transmission region; the second light-shielding pattern is formed to have a width narrower than that of the upper phase shift pattern to form the phase shift region; It is possible. (11) A method for manufacturing a phase shift mask according to the present invention comprises the steps of: the first etching solution contains ceric ammonium nitrate; the second etching solution contains hydrofluoric acid; the third etching solution contains ceric ammonium nitrate; It is possible.

[0012] (1) A phase shift mask blank according to one aspect of the present invention, A phase shift mask blank having a mask layer that serves as a phase shift mask, a phase shift layer laminated on a transparent substrate; a light-shielding layer laminated on the phase shift layer; and The phase shift layer comprises: a lower phase shift layer laminated on the transparent substrate; an upper phase shift layer stacked on the lower phase shift layer; and the lower phase shift layer and the light-shielding layer can be etched with the same etchant; the upper phase shift layer is etchable with an etchant different from that of the lower phase shift layer and the light-shielding layer; This solved the above problem.

[0013] In the above-described configuration of the present invention, a phase shift mask can be manufactured by forming a resist pattern from a phase shift mask blank only once, without stripping and re-forming the resist pattern. In this configuration, a first light-shielding pattern can be formed from the light-shielding layer by a first wet etching. In this configuration, an upper phase shift pattern can be formed from the upper phase shift layer by a second wet etching, with the same width as the first light-shielding pattern. In this configuration, a lower phase shift pattern can be formed from the lower phase shift layer by a third wet etching, with the same width as the upper phase shift pattern. Furthermore, in this configuration, a second light-shielding pattern can be formed from the first light-shielding pattern with a narrower width than the upper phase shift pattern by side etching performed simultaneously with the third wet etching.

[0014] As a result, a phase shift region without the second light-shielding pattern can be formed at the widthwise end of the upper phase shift pattern. Also, a transmissive region where the transparent substrate is exposed can be formed by removing the lower phase shift layer. In this case, the upper and lower phase shift patterns can be formed with the same width to form the phase shift pattern. In other words, this configuration makes it possible to provide a phase shift mask blank that can be used to manufacture a phase shift mask having a phase shift pattern formed thereon in which the transmittance, phase shift state, film thickness, etching time, and side etching time are all optimized, without the need to form resist patterns twice, which requires alignment.

[0015] In this case, the surface of the transparent substrate is not exposed during the wet etching of the upper phase shift layer, which would otherwise damage the surface of the transparent substrate. This allows the surface damage of the transparent substrate to be kept extremely suppressed. Furthermore, in the third wet etching that exposes the surface of the transparent substrate, an etching solution different from that used in the second wet etching, which would damage the surface of the transparent substrate, can be used. This allows the surface damage of the transparent substrate to be kept extremely suppressed.

[0016] Moreover, this state allows the formation of a transmission region with a favorable surface state. Furthermore, the required optical characteristics of the phase shift layer, such as transmission characteristics, film thickness, and phase shift characteristics, as well as the amount of side etching from the first light-shielding pattern, can be appropriately controlled for the two layers, the lower phase shift layer and the upper phase shift layer. This allows the formation of a phase shift region with the required predetermined characteristics. Therefore, the influence of etching with hydrofluoric acid on the transparent substrate, which is a glass substrate, can be reduced. The phase shift characteristics are not changed by etching the glass substrate.

[0017] Furthermore, in the third wet etching, the amount of side etching from the first light-shielding pattern and the removal state of the lower phase shift layer, which are performed simultaneously, can be appropriately controlled. As a result, the lower phase shift pattern and the upper phase shift pattern can be formed to have equal widths by the third wet etching. Therefore, a phase shift mask with an appropriate phase shift pattern can be manufactured. At the same time, since the surface of the transparent substrate is less damaged, this phase shift mask can be recycled without undergoing a re-polishing process.

[0018] (2) The phase shift mask blank of the present invention, in the above (1), In a state in which a first light-shielding pattern formed by etching from the light-shielding layer and an upper phase shift pattern formed by etching from the upper phase shift layer are formed to have the same width, a lower phase shift pattern having the same width as the upper phase shift pattern is formed from the lower phase shift layer to form a transparent region of the phase shift mask, a second light-shielding pattern formed by side etching from the first light-shielding pattern has a width narrower than that of the upper phase shift pattern, and can form a phase shift region of the phase shift mask; It is possible.

[0019] In the above-described configuration of the present invention, the lower phase shift pattern, the upper phase shift pattern, and the second light-shielding pattern can be formed by multiple wet etchings without stripping and reforming the resist pattern. In this case, the first wet etching forms the first light-shielding pattern from the light-shielding layer. The second wet etching forms the upper phase shift pattern from the upper phase shift layer with the same width as the first light-shielding pattern. The third wet etching forms the lower phase shift pattern from the lower phase shift layer with the same width as the upper phase shift pattern. Furthermore, side etching, which is performed simultaneously with the third wet etching, forms the second light-shielding pattern from the first light-shielding pattern with a narrower width than the upper phase shift pattern.

[0020] As a result, a phase shift region without the second light-shielding pattern can be formed at the widthwise end of the upper phase shift pattern. Also, a transmissive region where the transparent substrate is exposed can be formed by removing the lower phase shift layer. In this case, the upper and lower phase shift patterns can be formed with the same width to form the phase shift pattern.

[0021] Furthermore, a transmission region with a favorable surface condition can be formed. Furthermore, the required optical characteristics of the phase shift layer, such as transmission characteristics, film thickness, and phase shift characteristics, as well as the amount of side etching from the first light-shielding pattern, can be appropriately controlled for the two layers, the lower phase shift layer and the upper phase shift layer. Therefore, a phase shift region with the required characteristics can be formed.

[0022] (3) The phase shift mask blank of the present invention, in the above (2), the thickness of the lower phase shift layer is smaller than the thickness of the light-shielding layer; It is possible.

[0023] In the above-described configuration of the present invention, the amount of side etching from the first light-shielding pattern and the state of removal of the lower phase shift layer, which are simultaneously performed in the third wet etching, can be appropriately controlled, thereby forming the lower phase shift pattern and the upper phase shift pattern with equal widths in the third wet etching, thereby manufacturing a phase shift mask having appropriate phase shift patterns.

[0024] (4) The phase shift mask blank of the present invention, in the above (3), a thickness of the lower phase shift layer is smaller than a side etching amount of the first light-shielding pattern; It is possible.

[0025] In the above-described configuration of the present invention, the amount of side etching from the first light-shielding pattern can be appropriately controlled in the third wet etching, and at the same time, the lower phase shift pattern and the upper phase shift pattern can be formed to have the same width, thereby manufacturing a phase shift mask having an appropriate phase shift pattern.

[0026] (5) The phase shift mask blank of the present invention, in the above (4), The width of the phase shift region is 4.0 to 500 times the thickness of the lower phase shift layer. It is possible.

[0027] In the above-described configuration of the present invention, in the third wet etching, the amount of side etching from the first light-shielding pattern, which is performed simultaneously, can be appropriately controlled with respect to the state of removal of the lower phase shift layer. This allows the width dimension of the phase shift region to be appropriately formed. As a result, the third wet etching forms the lower phase shift pattern and the upper phase shift pattern with equal widths, making it possible to manufacture a phase shift mask with appropriate phase shift patterns.

[0028] (6) The phase shift mask blank of the present invention, in the above (5), an etching rate of the lower phase shift layer is 1 / 11 to 1 / 2 times the side etching rate of the light-shielding layer; It is possible.

[0029] In the above-described configuration of the present invention, the lower phase shift pattern and the upper phase shift pattern are formed to have equal widths in the third wet etching, thereby manufacturing a phase shift mask having an appropriate phase shift pattern.

[0030] (7) The phase shift mask blank of the present invention is, in the above (6), the light-shielding layer contains chromium, the lower phase shift layer contains one or more selected from chromium, nickel, molybdenum, niobium, and titanium; the upper phase shift layer contains silicon and has etching selectivity with respect to the lower phase shift layer and the light-shielding layer; It is possible.

[0031] In the above configuration of the present invention, an upper phase shift pattern is formed in the second wet etching. Also, in the third wet etching, a second light-shielding pattern is formed by side etching from the first light-shielding pattern using the same type of first etching solution as in the first wet etching. At the same time, in the third wet etching, a lower phase shift pattern can be formed from the lower phase shift layer by wet etching.

[0032] Furthermore, by making the light-shielding layer and the lower phase shift layer have predetermined compositions, a lower phase shift pattern having the same width as the upper phase shift pattern can be formed in the third wet etching, and at this time, the second light-shielding pattern can be formed to have a phase shift region of a predetermined width.

[0033] (8) A phase shift mask according to another aspect of the present invention comprises: A phase shift mask manufactured from the phase shift mask blank according to any one of (2) to (6) above, The surface roughness of the transparent substrate in the transmission region is in the range of Ra 0.14 nm to Ra 2.5 nm. It is possible.

[0034] In the above-described configuration of the present invention, in the third wet etching in which the transparent substrate is exposed by removing the lower phase shift layer, the lower phase shift layer can be removed without using a second etching solution that damages the surface of the transparent substrate. This allows the transparent substrate to be exposed and a transmissive region to be formed without damaging the surface of the transparent substrate when removing the lower phase shift layer. Therefore, the influence of etching with hydrofluoric acid on the transparent substrate, which is a glass substrate, can be reduced. The phase shift characteristics of the glass substrate are not changed by etching.

[0035] In the wet etching of the upper phase shift layer, which damages the surface of the transparent substrate, the surface of the transparent substrate is not exposed. Therefore, it is possible to maintain a range in which surface damage to the transparent substrate is extremely suppressed. Furthermore, in the wet etching for removing the lower phase shift layer during recycling, an etching solution different from that used in the wet etching for removing the upper phase shift layer, which damages the surface of the transparent substrate, can be used. Therefore, it is possible to maintain a state in which surface damage to the transparent substrate is extremely suppressed. Therefore, it is easy to recycle this phase shift mask without undergoing a re-polishing process.

[0036] (9) Another aspect of the present invention is a method for manufacturing a phase shift mask, A method for manufacturing a phase shift mask according to (8) above, preparing a phase shift mask blank in which the lower phase shift layer, the upper phase shift layer, and the light-shielding layer formed on the transparent substrate are laminated; a first etching step of forming the first light-shielding pattern from the light-shielding layer by wet etching using a first etching solution, using a resist pattern formed by laminating on the light-shielding layer as a mask; a second etching step of forming the upper phase shift pattern from the upper phase shift layer by wet etching using at least the etched first light-shielding pattern as a mask and a second etching liquid different from the first etching liquid; a third etching step of forming a second light-shielding pattern from the first light-shielding pattern by side etching using a third etching solution that is the same as the first etching solution, using at least the resist pattern as a mask, and simultaneously forming a lower phase shift pattern from the lower phase shift layer by wet etching; and the resist pattern is not peeled off in the first etching step, the second etching step, and the third etching step; It is possible.

[0037] In the above configuration of the present invention, a resist pattern is formed only once on a phase shift mask blank. The resist pattern is not stripped and re-formed from the start of the first etching step to the end of the third etching step. In the first wet etching (first etching step), a first light-shielding pattern is formed from the light-shielding layer. In the second wet etching (second etching step), an upper phase shift pattern is formed from the upper phase shift layer to have the same width as the first light-shielding pattern. In the third wet etching (third etching step), a lower phase shift pattern is formed from the lower phase shift layer to have the same width as the upper phase shift pattern. At the same time, in this third wet etching, side etching is simultaneously performed to form a second light-shielding pattern from the first light-shielding pattern to have a narrower width than the upper phase shift pattern. This allows a phase shift region without the second light-shielding pattern to be formed at the widthwise end of the upper phase shift pattern. The lower phase shift layer can be removed to form a transmissive region where the transparent substrate is exposed. In this case, the upper and lower phase shift patterns can be formed with the same width, thereby forming a phase shift pattern with a flush cross section. This method eliminates the need to form resist patterns twice for alignment, and enables the manufacture of phase shift masks with phase shift patterns that are optimized for transmittance, phase shift state, film thickness, and etching time.

[0038] In the manufacture of a phase shift mask, the surface of the transparent substrate is not exposed during the wet etching of the upper phase shift layer, which would otherwise damage the surface of the transparent substrate. This allows for extremely suppressed surface damage to the transparent substrate. Furthermore, in the third wet etching, which exposes the surface of the transparent substrate, a different etchant is used than the second wet etching, which would damage the surface of the transparent substrate. This allows for extremely suppressed surface damage to the transparent substrate.

[0039] This allows the formation of a transmission region with a favorable surface condition. In addition, by combining the two layers, the lower phase shift layer and the upper phase shift layer, the required optical properties of the phase shift layer, such as transmission properties, film thickness, and phase shift properties, and the amount of side etching from the first light-shielding pattern, a phase shift region with required characteristics can be formed.

[0040] Furthermore, in the third wet etching, the amount of side etching from the first light-shielding pattern and the state of removal of the lower phase shift layer, which are simultaneously performed, can be appropriately controlled, thereby forming the lower phase shift pattern and the upper phase shift pattern with equal widths by the third wet etching, thereby manufacturing a phase shift mask with appropriate phase shift patterns.

[0041] (10) A method for manufacturing a phase shift mask according to the present invention comprises the steps of: In the second etching step, the first light-shielding pattern and the upper phase shift pattern are formed to have the same width; In the third etching step, the upper phase shift pattern and the lower phase shift pattern are formed to have the same width to form the transmission region; the second light-shielding pattern is formed to have a width narrower than that of the upper phase shift pattern to form the phase shift region; It is possible.

[0042] The above-described configuration of the present invention can provide a phase shift mask blank capable of manufacturing a phase shift mask having a phase shift pattern formed thereon in which the transmittance, phase shift state, film thickness, and etching time are all optimized.

[0043] (11) A method for manufacturing a phase shift mask according to the present invention comprises the steps of: the first etching solution contains ceric ammonium nitrate; the second etching solution contains hydrofluoric acid; the third etching solution contains ceric ammonium nitrate; It is possible.

[0044] Furthermore, the first etching solution used in the third etching step contains nitric acid. It is possible.

[0045] In the above-described configuration of the present invention, a transmission region with a favorable surface condition is formed, and a phase shift region having required predetermined characteristics can be formed by appropriately controlling the required optical characteristics of the phase shift layer, such as transmission characteristics, film thickness, and phase shift characteristics, and the amount of side etching from the first light-shielding pattern in the two layers of the lower phase shift layer and the upper phase shift layer. The effects of etching with hydrofluoric acid on a transparent substrate, such as a glass substrate, can be reduced. The phase shift characteristics are not changed by etching the glass substrate.

[0046] Further, specific compositions are described below. The bottom phase shift layer can contain, for example, chromium. The lower phase shift layer can contain, for example, chromium or nickel. The bottom phase shift layer can contain, for example, nickel. The bottom phase shift layer can contain, for example, molybdenum. The bottom phase shift layer can contain, for example, niobium. The bottom phase shift layer can contain, for example, titanium. In addition to any of the above, the lower phase shift layer may contain one or more elements selected from carbon, oxygen, and nitrogen. Furthermore, the lower phase shift layer can be formed by sputtering, and the above composition can be realized by controlling the target composition used in the process.

[0047] The top phase shift layer may contain silicon.The top phase shift layer may contain molybdenum. In addition to the above, the upper phase shift layer may contain one or more elements selected from carbon, oxygen, and nitrogen. Furthermore, the upper phase shift layer can be formed by sputtering, and the above composition can be realized by controlling the target composition used in the process. The light-shielding layer may contain chromium. In addition to the above, the light-shielding layer may contain one or more elements selected from carbon, oxygen, and nitrogen. Furthermore, the light-shielding layer can be formed by sputtering, and the above composition can be realized by controlling the target composition used in the process. [Effects of the Invention]

[0048] According to the present invention, it is possible to achieve the effects of reducing the occurrence of damage to the surface of the transparent substrate while maintaining the phase shift characteristics, making it possible to manufacture a phase shift mask without causing changes in the phase shift characteristics, and making it possible to recycle the transparent substrate without undergoing a re-polishing process. [Brief explanation of the drawings]

[0049] [Figure 1]1 is a cross-sectional view showing a first embodiment of a phase shift mask blank according to the present invention. [Figure 2] 1 is an enlarged cross-sectional view showing a first embodiment of a phase shift mask blank according to the present invention. [Figure 3] 1 is a schematic diagram showing a film formation apparatus in a first embodiment of a method for producing a phase shift mask blank according to the present invention. [Figure 4] 1A to 1C are cross-sectional views showing the steps of a manufacturing method for a phase shift mask according to a first embodiment of the present invention. [Figure 5] 1A to 1C are cross-sectional views showing the steps of a manufacturing method for a phase shift mask according to a first embodiment of the present invention. [Figure 6] 1A to 1C are cross-sectional views showing the steps of a manufacturing method for a phase shift mask according to a first embodiment of the present invention. [Figure 7] 1A to 1C are cross-sectional views showing the steps of a manufacturing method for a phase shift mask according to a first embodiment of the present invention. [Figure 8] 1A to 1C are cross-sectional views showing the steps of a manufacturing method for a phase shift mask according to a first embodiment of the present invention. [Figure 9] 1 is a cross-sectional view showing a first embodiment of a phase shift mask according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0050] A first embodiment of a phase shift mask blank, a phase shift mask, and a manufacturing method thereof according to the present invention will be described below with reference to the drawings. Fig. 1 is a cross-sectional view showing a phase shift mask blank in this embodiment. Fig. 2 is an enlarged cross-sectional view showing a portion designated by reference numeral 12p in Fig. 1. In the figure, reference numeral 10B denotes a phase shift mask blank.

[0051] The phase shift mask blank 10B according to this embodiment is intended to be used as a phase shift mask (photomask) for use with exposure light having a wavelength in the range of approximately 365 nm to 436 nm, or approximately 290 to 380 nm. As shown in FIG. 1, the phase shift mask blank 10B according to this embodiment is composed of a glass substrate (transparent substrate) 11, a phase shift layer 12 formed on this glass substrate 11, and a light-shielding layer 13 formed on the phase shift layer 12.

[0052] The phase shift layer 12 is formed directly on the surface of the glass substrate 11. The light-shielding layer 13 is provided at a position farther away from the glass substrate 11 than the phase shift layer 12. The light-shielding layer 13 is formed directly on the surface of the phase shift layer 12. The phase shift layer 12 is sandwiched between the glass substrate 11 and the light-shielding layer 13. Phase shift layer 12 and light-shielding layer 13 have the optical properties required for a photomask. Phase shift layer 12 and light-shielding layer 13 constitute a mask layer, which is a phase shift film that can shift the phase of exposure light by approximately 180°.

[0053] The phase shift mask blank 10B according to this embodiment may have a configuration in which a photoresist layer 15 is formed on the mask layer in advance (see FIG. 4 described later).

[0054] In addition to the phase shift layer 12 and the light-shielding layer 13, the phase shift mask blank 10B according to this embodiment may have a mask layer formed by laminating an antireflection layer, an adhesion layer, a chemical-resistant layer, a protective layer, an etching stopper layer, etc. Furthermore, the phase shift mask blank 10B according to this embodiment may have a photoresist layer 15 formed on these laminated films (see FIG. 4 described later).

[0055] The glass substrate (transparent substrate) 11 is made of a material having excellent transparency and optical isotropy. For example, a quartz glass substrate is used as the glass substrate 11. The size of the glass substrate 11 is not particularly limited. The size of the glass substrate 11 is appropriately selected according to the substrate to be exposed using the phase shift mask. The substrate to be exposed using the phase shift mask is, for example, a substrate for an FPD such as an LCD (liquid crystal display), a plasma display, or an organic EL (electroluminescence) display.

[0056] The glass substrate 11 can be a rectangular substrate with a side of about 100 mm. The glass substrate 11 may be a rectangular substrate with a side of more than 100 mm. The glass substrate 11 can be a rectangular substrate with a side of 2000 mm or more. The glass substrate 11 can be a substrate with a thickness of 1 mm or less. The glass substrate 11 can be a substrate with a thickness of more than 1 mm. The glass substrate 11 can be a substrate with a thickness of several mm. The glass substrate 11 can also be a substrate with a thickness of 10 mm or more.

[0057] Furthermore, the surface flatness of the glass substrate 11 may be reduced. The surface flatness of the glass substrate 11 is reduced by polishing the surface. The flatness of the glass substrate 11 can be reduced to, for example, 20 μm or less. Reducing the surface flatness of the glass substrate 11 increases the depth of focus of the mask. Reducing the surface flatness of the glass substrate 11 can greatly contribute to the formation of fine and highly accurate patterns. Furthermore, the surface flatness of the glass substrate 11 can be reduced to 10 μm or less. It is preferable that the surface flatness of the glass substrate 11 is reduced.

[0058] The glass substrate 11 that has undergone the polishing process has reduced surface flatness. In contrast, the glass substrate 11 that has been recycled without undergoing the polishing process has rougher surface flatness than the glass substrate 11 that has undergone the polishing process. In this embodiment, either type of glass substrate 11 can be used. Specifically, the glass substrate 11 that has undergone the polishing process has a surface flatness of approximately Ra10.0 μm to Ra2.0 μm, while the glass substrate 11 that has been recycled without undergoing the polishing process has a surface flatness of approximately Ra10.0 μm to Ra2.0 μm.

[0059] As shown in FIG. 2, the phase shift layer 12 has a lower phase shift layer 12a laminated on the transparent substrate 11 and an upper phase shift layer 12b laminated on the lower phase shift layer 12a. The lower phase shift layer 12a and the upper phase shift layer 12b act together as the phase shift layer 12. Therefore, the optical characteristics of the lower phase shift layer 12a and the upper phase shift layer 12b combined as the phase shift layer 12 when used as a phase shift mask are set within a predetermined range.

[0060] The optical properties of the phase shift layer 12 are set to a refractive index of about 2.4 to 3.1, an extinction coefficient of 0.3 to 2.1, and a phase shift change of 180°, etc., for the lower phase shift layer 12a and the upper phase shift layer 12b combined, in a wavelength range of about 365 nm to 436 nm. To set the optical properties of the phase shift layer 12 within a predetermined range, the composition and film thickness of the lower phase shift layer 12a and the upper phase shift layer 12b combined are set within a predetermined range. The composition ratio and film thickness of phase shift layer 12 are set in accordance with the optical characteristics required for phase shift mask 10 to be manufactured.

[0061] The phase shift layer 12, including the lower phase shift layer 12a and the upper phase shift layer 12b, has a combined thickness of 100 nm to 200 nm. The phase shift layer 12, including the lower phase shift layer 12a and the upper phase shift layer 12b, has a combined thickness of 120 nm to 150 nm. The phase shift layer 12, including the lower phase shift layer 12a and the upper phase shift layer 12b, has a combined thickness of 135 nm to 145 nm.

[0062] The lower phase shift layer 12a is set to have a smaller thickness than the upper phase shift layer 12b. The lower phase shift layer 12a is set to have a smaller refractive index than the upper phase shift layer 12b. The lower phase shift layer 12a is set to have a higher transmittance than the upper phase shift layer 12b. The lower phase shift layer 12a is set to have a lower reflectance than the upper phase shift layer 12b.

[0063] As will be described later, the lower phase shift layer 12a can be etched with the same etching solution as the light-shielding layer 13. The lower phase shift layer 12a can be etched with the same etching solution as the light-shielding layer 13 containing chromium. Specifically, an etching solution containing cerium diammonium nitrate can be used as the etching solution for chromium-based materials. It is preferable to use cerium diammonium nitrate containing an acid such as nitric acid or perchloric acid as the etching solution for chromium-based materials.

[0064] As described below, the lower phase shift layer 12a can be etched with the same etching solution as the upper phase shift layer 12b. The lower phase shift layer 12a can be etched with the same etching solution as the upper phase shift layer 12b containing silicide. To etch the upper phase shift layer 12b made of molybdenum silicide, an etching solution capable of etching molybdenum silicide is used. Specifically, an etching solution capable of etching the upper phase shift layer 12b can be an etching solution containing at least one fluorine compound selected from hydrofluoric acid, hydrosilicic acid, and ammonium bifluoride. The lower phase shift layer 12a can be etched with an etching solution containing at least one fluorine compound selected from hydrofluoric acid, hydrosilicic acid, and ammonium bifluoride. The lower phase shift layer 12a can be etched with, for example, a mixture of ammonium bifluoride and hydrogen peroxide.

[0065] The lower phase shift layer 12a may contain at least a selected material such as chromium, nickel, etc. The lower phase shift layer 12a may contain, for example, chromium. The lower phase shift layer 12a may contain, for example, chromium and nickel. The lower phase shift layer 12a may contain, for example, nickel. The lower phase shift layer 12a may contain, for example, molybdenum. The lower phase shift layer 12a may contain, for example, niobium. The lower phase shift layer 12a may contain, for example, titanium. Furthermore, the lower phase shift layer 12a may contain, in addition to any of the above, one or more elements selected from carbon, oxygen, and nitrogen. The lower phase shift layer 12a has etching selectivity with respect to the above-mentioned etching solution that etches the upper phase shift layer 12b.

[0066] The composition ratio of Cr, C, O, and N in the lower phase shift layer 12a can be set as follows: Cr: 67-30 atm %, C: 10-30 atm %, O: 3-10 atm %, and N: 20-30 atm %, respectively.

[0067] The composition ratios of Ni, Mo, Nb, Ti, C, O, and N in the lower phase shift layer 12a can be Ni: 30 to 40 atm%, Mo: 10 to 15 atm%, Nb: 5 to 7 atm%, Ti: 3 to 5 atm%, C: 24 to 30 atm%, O: 6 to 14 atm%, and N: 4 to 7 atm%, respectively.

[0068] The thickness of the lower phase shift layer 12a is set in the range of 10 nm to 30 nm. The thickness of the lower phase shift layer 12a is set in the range of 12 nm to 20 nm. The thickness of the lower phase shift layer 12a is set in the range of 13 nm to 15 nm. The lower phase shift layer 12a has a thickness of 20 nm or less. The thickness of the lower phase shift layer 12a is set to be ⅙ or less of the thickness of the phase shift layer 12. The thickness of the lower phase shift layer 12a is in the range of 10.0 nm% to 20.0 nm% of the thickness of the phase shift layer 12.

[0069] The lower phase shift layer 12a has an etching rate lower than that of the light-shielding layer 13. The etching rate of the lower phase shift layer 12a is in the range of 1.0 nm / min to 6.0 nm / min.

[0070] When the lower phase shift layer 12a contains a large amount of chromium, the following method can be used. The refractive index of the lower phase shift layer 12a can be reduced by increasing the oxygen concentration in the chromium compound. The extinction coefficient of the lower phase shift layer 12a can be reduced by increasing the oxygen concentration in the chromium compound. The refractive index of the lower phase shift layer 12a can be reduced by increasing the nitrogen concentration in the chromium compound. The extinction coefficient of the lower phase shift layer 12a can be reduced by increasing the nitrogen concentration in the chromium compound. The refractive index of the lower phase shift layer 12a can be increased by decreasing the oxygen concentration in the chromium compound. The extinction coefficient of the lower phase shift layer 12a can be increased by decreasing the oxygen concentration in the chromium compound. The refractive index of the lower phase shift layer 12a can be increased by decreasing the nitrogen concentration in the chromium compound. The extinction coefficient of the lower phase shift layer 12a can be increased by decreasing the nitrogen concentration in the chromium compound.

[0071] The upper phase shift layer 12b is a metal silicide film containing silicon and a metal such as Ta, Ti, W, Mo, or Zr, or an alloy of these metals. The upper phase shift layer 12b is a molybdenum silicide film. The upper phase shift layer 12b contains O (oxygen). The upper phase shift layer 12b contains N (nitrogen). The upper phase shift layer 12b contains C (carbon). The upper phase shift layer 12b is MoSi X (X≧2) film. The upper phase shift layer 12b is a MoSi2 film. The upper phase shift layer 12b is a MoSi3 film. The upper phase shift layer 12b is a MoSi4 film.

[0072] The upper phase shift layer 12b may not be etched with the same etchant as the lower phase shift layer 12a and the light-shielding layer 13. Alternatively, the upper phase shift layer 12b may have selectivity to an etchant that etches a film containing a selected material such as chromium or nickel.

[0073] The upper phase shift layer 12b may have a region with a different silicon to molybdenum concentration ratio Si / Mo in the film thickness direction. The upper phase shift layer 12b may have a region with a different O (oxygen) concentration in the film thickness direction. The upper phase shift layer 12b may have a region with a different N (nitrogen) concentration in the film thickness direction. The upper phase shift layer 12b may have a region with a different C (carbon) concentration in the film thickness direction.

[0074] The upper phase shift layer 12b has a thickness set in the range of 100 nm to 150 nm. The upper phase shift layer 12b has a thickness set in the range of 120 nm to 190 nm. The upper phase shift layer 12b has a thickness set in the range of 130 nm to 180 nm.

[0075] The upper phase shift layer 12b has a carbon concentration in the range of 1.5 atm% to 5.0 atm%. The upper phase shift layer 12b has a nitrogen concentration in the range of 30.0 atm% to 40.0 atm%. The upper phase shift layer 12b has an oxygen concentration in the range of 4.0 atm% to 8.0 atm%. The upper phase shift layer 12b has a silicon concentration in the range of 30.0 atm% to 40.0 atm%. The upper phase shift layer 12b has a molybdenum concentration in the range of 15.0 atm% to 21.0 atm%.

[0076] Alternatively, the upper phase shift layer 12b has a carbon concentration (carbon content) in the range of 0.1 atm% to 1.5 atm%. The upper phase shift layer 12b has a nitrogen concentration in the range of 40 atm% to 60 atm%. The upper phase shift layer 12b has an oxygen concentration (oxygen content) in the range of 0.1 atm% to 4.0 atm%. The upper phase shift layer 12b has a silicon concentration (silicon content) in the range of 30.0 atm% to 40.0 atm%. The upper phase shift layer 12b has a molybdenum concentration (molybdenum content) in the range of 10.0 atm% to 20.0 atm%.

[0077] The upper phase shift layer 12b has a silicon to molybdenum concentration ratio Si / Mo in the range of 2.5≦Si / Mo≦2.6, or alternatively, the upper phase shift layer 12b has a silicon to molybdenum concentration ratio Si / Mo in the range of 1≦Si / Mo≦2.5.

[0078] The upper phase shift layer 12b is formed so that the composition ratio does not change in the film thickness direction.The upper phase shift layer 12b is formed so that the composition ratio is constant in the film thickness direction. Here, "forming a film with a constant composition ratio in the thickness direction" means forming a film to a predetermined thickness without changing the film formation conditions during film formation. "forming a film with a constant composition ratio in the thickness direction" means forming a film to a predetermined thickness while maintaining constant film formation conditions during film formation.

[0079] The upper phase shift layer 12b is formed with a concentration gradient such that the composition ratio changes in the film thickness direction. In this case, the upper phase shift layer 12b may have a lower carbon concentration (carbon content) and silicon concentration (silicon content) at a position away from the light-shielding layer 13 in the film thickness direction than at a position away from the light-shielding layer 13. The upper phase shift layer 12b may have a lower carbon concentration (carbon content) at a position away from the light-shielding layer 13 in the film thickness direction than at a position away from the light-shielding layer 13. The upper phase shift layer 12b may have a lower oxygen concentration (oxygen content) at a position away from the light-shielding layer 13 in the film thickness direction than at a position away from the light-shielding layer 13. The upper phase shift layer 12b may have a lower molybdenum concentration (molybdenum content) at a position away from the light-shielding layer 13 in the film thickness direction than at a position away from the light-shielding layer 13. The upper phase shift layer 12b may have a higher nitrogen concentration (nitrogen content) at a position spaced apart from the light-shielding layer 13 in the film thickness direction than at a position spaced apart from the light-shielding layer 13.

[0080] The light-shielding layer 13 is laminated on the upper phase shift layer 12b. The light-shielding layer 13 is farther from the glass substrate 11 than the phase shift layer 12. The light-shielding layer 13 is in contact with the upper phase shift layer 12b. The light-shielding layer 13 contains Cr (chromium) as a main component. The light-shielding layer 13 contains O (oxygen) as a main component. The light-shielding layer 13 contains C (carbon). The light-shielding layer 13 contains N (nitrogen). The light-shielding layer 13 can also be formed by laminating one or more materials selected from chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium carbonitride, and chromium oxycarbonitride.

[0081] Furthermore, the light-shielding layer 13 may have a composition that varies in the thickness direction. For example, the light-shielding layer 13 may have a nitrogen concentration that varies in the thickness direction. The light-shielding layer 13 may have an oxygen concentration that varies in the thickness direction. The light-shielding layer 13 may have a carbon concentration that varies in the thickness direction.

[0082] As will be described later, the concentrations (composition ratio; atm %) of chromium, nitrogen, carbon, oxygen, etc. of light-shielding layer 13 are set so as to obtain predetermined optical characteristics. The film thickness of light-shielding layer 13 is set so as to obtain predetermined optical characteristics. The film characteristics of light-shielding layer 13 vary depending on the composition ratio of chromium, nitrogen, carbon, oxygen, etc. The film thickness of light-shielding layer 13 can be set particularly depending on the optical characteristics required for phase shift mask 10.

[0083] If the light-shielding layer 13 is not set to the above conditions, side etching will not be performed properly during the etching process for forming the mask pattern (described later), and the phase shift region ps will not be accurately formed relative to the upper phase shift pattern 12bP1, which is undesirable. If the light-shielding layer 13 is not set to the above conditions, the resulting mask pattern will have a non-perpendicular cross-sectional shape, which is undesirable. Furthermore, if the light-shielding layer 13 is not set to the above conditions, it will be difficult to set the optical characteristics of the photomask to the desired conditions, which is undesirable.

[0084] The refractive index of the light-shielding layer 13 can be reduced by increasing the oxygen concentration in the chromium compound. The extinction coefficient of the light-shielding layer 13 can be reduced by increasing the oxygen concentration in the chromium compound. The refractive index of the light-shielding layer 13 can be reduced by increasing the nitrogen concentration in the chromium compound. The extinction coefficient of the light-shielding layer 13 can be reduced by increasing the nitrogen concentration in the chromium compound. The refractive index of the light-shielding layer 13 can be increased by lowering the oxygen concentration in the chromium compound. The extinction coefficient of the light-shielding layer 13 can be increased by lowering the oxygen concentration in the chromium compound. The refractive index of the light-shielding layer 13 can be increased by lowering the nitrogen concentration in the chromium compound. The extinction coefficient of the light-shielding layer 13 can be increased by lowering the nitrogen concentration in the chromium compound.

[0085] In this embodiment, phase shift mask blank 10B can be used to manufacture phase shift mask 10 by forming a resist pattern only once, without stripping and re-forming resist pattern 15P1. Phase shift mask blank 10B can be used to manufacture phase shift mask 10 without changing the phase shift characteristics due to etching during patterning. Phase shift mask blank 10B does not cause a change in the phase of set phase shift layer 12 due to etching during patterning. Phase shift mask blank 10B does not cause a change in the surface condition of glass substrate 11 due to etching during patterning. Phase shift mask blank 10B can be used to manufacture phase shift mask 10 without causing surface damage to glass substrate 11 due to etching during patterning.

[0086] The method for manufacturing a phase shift mask blank according to this embodiment will be described below with reference to the drawings.

[0087] FIG. 3 is a schematic diagram showing a manufacturing apparatus for a phase shift mask blank in this embodiment. The phase shift mask blank 10B in this embodiment is manufactured by the manufacturing apparatus shown in FIG.

[0088] The manufacturing apparatus S10 is an inter-back sputtering apparatus as shown in Fig. 3. The manufacturing apparatus S10 has a load chamber S11, an unload chamber S16, and a film formation chamber (vacuum processing chamber) S12.

[0089] The load chamber S11 has a transfer mechanism S11a and an exhaust mechanism S11f. The transfer mechanism S11a transfers the glass substrate 11 carried in from the outside to the film formation chamber S12. The exhaust mechanism S11f roughly evacuates the inside of the load chamber S11. The exhaust mechanism S11f is a rotary pump or the like. The load chamber S11 is connected to the film formation chamber S12 via a sealing mechanism S17.

[0090] The unloading chamber S16 has a transfer mechanism S16a and an exhaust mechanism S16f. The transfer mechanism S16a transports the glass substrate 11, which has been transferred from the film forming chamber S12 and on which film formation has been completed, to the outside. The exhaust mechanism S16f roughly evacuates the inside of the unloading chamber S16. The exhaust mechanism S16f is a rotary pump or the like. The unloading chamber S16 is connected to the film forming chamber S12 via a sealing mechanism S18.

[0091] The film formation chamber S12 includes a substrate holding mechanism S12a, a film formation mechanism S13, a film formation mechanism S14, a film formation mechanism S15, and a gas barrier S12g. The film formation chamber S12 is a mechanism capable of three-stage film formation processes with the three film formation mechanisms S13 and S14.

[0092] The substrate holding mechanism S12a receives the glass substrate 11 transported by the transport mechanism S11a. The substrate holding mechanism S12a holds the glass substrate 11 inside the film formation chamber S12. The substrate holding mechanism S12a holds the glass substrate 11 so that it faces the targets S13b, S14b, and S15b during film formation. The substrate holding mechanism S12a transports the glass substrate 11 inside the film formation chamber S12. The substrate holding mechanism S12a hands over the glass substrate 11 to the transport mechanism S16a. The substrate holding mechanism S12a is capable of applying bias power to the glass substrate 11 during film formation.

[0093] The film formation mechanism S13 is disposed in the film formation chamber S12 at a position closest to the load chamber S11. The film formation mechanism S13 performs the first stage of the three-stage film formation process. The film formation mechanism S13 supplies film formation materials for the first stage of the film formation process. The film forming mechanism S13 includes a target S13b, a cathode electrode (backing plate) S13c, a power source S13d, a gas introducing mechanism S13e, and a high-vacuum exhaust mechanism S13f.

[0094] The target S13b supplies the first-stage film forming material. The target S13b is attached to the cathode electrode S13c. The power supply S13d applies a negative sputtering voltage to the backing plate S13c. The gas introduction mechanism S13e introduces the first-stage film formation gas into the film formation chamber S12. The gas introduction mechanism S13e introduces the first-stage film formation gas into the film formation mechanism S13. The gas introduction mechanism S13e introduces the film formation gas mainly near the cathode electrode S13c. The high-vacuum exhaust mechanism S13f evacuates the inside of the film formation chamber S12. The high-vacuum exhaust mechanism S13f draws a high vacuum mainly near the cathode electrode S13c. The high-vacuum exhaust mechanism S13f is a turbomolecular pump or the like. The film forming mechanism S13 may include a magnetron magnetic circuit, which forms a predetermined magnetic field on the target S13b.

[0095] The film formation mechanism S14 is disposed inside the film formation chamber S12 at a central position between the load chamber S11 and the unload chamber S16. The film formation mechanism S14 performs the second stage of the three-stage film formation process. The film formation mechanism S14 supplies film formation materials for the second stage of the film formation process. The film formation mechanism S14 has substantially the same configuration as the film formation mechanism S13, and includes a target S14b, a cathode electrode (backing plate) S14c, a power source S14d, a gas introduction mechanism S14e, and a high-vacuum exhaust mechanism S14f.

[0096] The film formation mechanism S15 is disposed inside the film formation chamber S12 at a position adjacent to the unload chamber S16. The film formation mechanism S15 performs the third film formation process of the three-stage film formation process. The film formation mechanism S15 supplies film formation materials for the third film formation process. The film formation mechanism S15 has substantially the same configuration as the film formation mechanism S 13. The film formation mechanism S15 includes a target S15b, a cathode electrode (backing plate) S15c, a power source S15d, a gas introduction mechanism S15e, and a high-vacuum exhaust mechanism S15f.

[0097] The film formation mechanisms S13, S14, and S15 are adjacent to each other inside the film formation chamber S12. The gas barrier S12g is disposed inside the film formation chamber S12. The gas barrier S12g is disposed between the film formation mechanism S13 and the film formation mechanism S14. The gas barrier S12g is disposed between the film formation mechanism S14 and the film formation mechanism S15. The gas barrier S12g separates the film formation gas between the film formation mechanism S13 and the film formation mechanism S14, and between the film formation mechanism S14 and the film formation mechanism S15. The gas barrier S12g is disposed to prevent the film formation gas from mixing between the film formation mechanism S13 and the film formation mechanism S14, and between the film formation mechanism S14 and the film formation mechanism S15. The gas barrier S12g suppresses the flow of the film formation gas between the film formation mechanism S13 and the film formation mechanism S14, and between the film formation mechanism S14 and the film formation mechanism S15. The gas barrier S12g is configured so that the substrate holding mechanism S12a can move among the film forming mechanism S13, the film forming mechanism S14, and the film forming mechanism S15.

[0098] The film formation mechanisms S13, S14, and S15 have the configurations required to perform the three-stage film formation processes, respectively. The film formation mechanisms S13, S14, and S15 can implement the conditions required to perform the three-stage film formation processes, respectively. The film formation mechanism S13 corresponds to the formation of the lower phase shift layer 12a. The film formation mechanism S14 corresponds to the formation of the upper phase shift layer 12b. The film formation mechanism S15 corresponds to the formation of the light-shielding layer 13.

[0099] In the film formation mechanisms S13 to S15, targets S13b to S15b have compositions necessary for forming the lower phase shift layer 12a, the upper phase shift layer 12b, and the light-shielding layer 13, respectively. The target S13b contains a selected material such as chromium or nickel. The target S14b is made of molybdenum silicide. The target S15b is made of chromium.

[0100] In the film formation mechanisms S13 to S15, gas introduction mechanisms S13e to S15e supply gases necessary for forming the lower phase shift layer 12a, the upper phase shift layer 12b, and the light-shielding layer 13, respectively. The gas introduction mechanisms S13e to S15e can select and supply process gases containing carbon, nitrogen, oxygen, etc. The gas introduction mechanisms S13e to S15e can supply sputtering gases such as argon and nitrogen gas.

[0101] Gas introduction mechanisms S13e to S15e and high-vacuum exhaust mechanisms S13f to S15f respectively set gas partial pressures required for forming lower phase shift layer 12a, upper phase shift layer 12b, and light-shielding layer 13. Gas introduction mechanisms S13e to S15e and high-vacuum exhaust mechanisms S13f to S15f can respectively change supply gas conditions in the film thickness direction of lower phase shift layer 12a, upper phase shift layer 12b, and light-shielding layer 13. Gas introduction mechanisms S13e to S15e and high-vacuum exhaust mechanisms S13f to S15f set conditions required for forming lower phase shift layer 12a, upper phase shift layer 12b, and light-shielding layer 13, respectively.

[0102] In the film formation mechanisms S13 to S15, power supplies S13d to S15d set sputtering voltages corresponding to the formation of lower phase shift layer 12a, upper phase shift layer 12b, and light-shielding layer 13, respectively. Power supplies S13d to S15d set conditions required for forming lower phase shift layer 12a, upper phase shift layer 12b, and light-shielding layer 13, respectively.

[0103] When manufacturing the phase shift mask blank 10B in the manufacturing apparatus S10, as a preparation step, the glass substrate 11 is carried into the load chamber S11. The glass substrate 11 is transported from the load chamber S11 to the film formation chamber S12 by the transport mechanism S11a. The glass substrate 11 is transported inside the film formation chamber S12 by the substrate holding mechanism S12a. Inside the film formation chamber S12, the glass substrate 11 undergoes a three-stage sputtering film formation process. After film formation is completed, the glass substrate 11 is transported from the film formation chamber S12 to the unload chamber S16 by the substrate holding mechanism S12a. The glass substrate 11 is then carried out to the outside by the transport mechanism S16a.

[0104] The method for manufacturing a phase shift mask blank in this embodiment includes a film-forming step of forming a mask layer on glass substrate 11. In the film-forming step, phase shift layer 12 is formed on glass substrate 11, and then light-shielding layer 13 is formed.

[0105] The film forming process includes a phase shift layer forming process including a lower phase shift layer forming process and an upper phase shift layer forming process, and a light-shielding layer forming process.

[0106] In the lower phase shift layer forming step, the lower phase shift layer 12a is formed on the glass substrate 11. The lower phase shift layer forming step is performed in a film forming mechanism S13. In the lower phase shift layer forming step, the film forming mechanism S13 supplies a process gas and a sputtering gas from the gas introduction mechanism S13e. In the lower phase shift layer forming step, the film forming mechanism S13 applies a sputtering voltage from the power supply S13d. In the lower phase shift layer forming step, the magnetron magnetic circuit may form a predetermined magnetic field on the target S13b.

[0107] In the lower phase shift layer forming step, the film formation mechanism S13 generates plasma near the target S13b. The plasma excites ions of the sputtering gas. The ions of the sputtering gas collide with the target S13b, ejecting particles of the film formation material. The particles of the film formation material ejected from the target S13b combine with the reactive gas and then adhere to the glass substrate 11. As a result, the lower phase shift layer 12a is formed on the surface of the glass substrate 11.

[0108] In the lower phase shift layer forming process, gases are supplied from the gas introduction mechanism S13e. The supplied gases include sputtering gas, carbon-containing gas, nitrogen-containing gas, and oxygen-containing gas. The gas introduction mechanism S13e supplies each gas at a predetermined partial pressure as the film thickness increases. The gas introduction mechanism S13e also switches to control each gas partial pressure as the film thickness increases. As a result, in the lower phase shift layer forming process, the composition of the lower phase shift layer 12a is adjusted to a predetermined concentration range in the film thickness direction by controlling the gas partial pressure. The lower phase shift layer forming step may vary the composition of the lower phase shift layer 12a in the film thickness direction. In this case, the lower phase shift layer forming step varies the partial pressure of each gas in the atmospheric gas according to the film thickness.

[0109] Examples of oxygen-containing gases include CO2 (carbon dioxide), O2 (oxygen), NO (nitrous oxide), NO (nitric oxide), and CO (carbon monoxide). Examples of carbon-containing gases include CO2 (carbon dioxide), CH4 (methane), CH6 (ethane), and CO (carbon monoxide). Examples of nitrogen-containing gases include N2 (nitrogen gas), NO (nitrous oxide), NO (nitric oxide), NO (nitrous oxide), and NH3 (ammonia).

[0110] In the lower phase shift layer forming step, the power supply S13d applies a plasma forming power to the cathode electrode S13c within a predetermined range.In the lower phase shift layer forming step, the power supply S13d applies a plasma forming power to the cathode electrode S13c within a predetermined range. In the lower phase shift layer forming step, the substrate holding mechanism S12a may apply bias power to the glass substrate 11.

[0111] The lower phase shift layer forming step uses a target S13b containing a selected material such as chromium, nickel, etc. The lower phase shift layer forming step uses a target S13b made of a selected material such as chromium, nickel, etc. In forming the lower phase shift layer 12a, the target S13b can be replaced as needed.

[0112] Similarly, the upper phase shift layer forming step forms the upper phase shift layer 12b on the lower phase shift layer 12a. The upper phase shift layer forming step is performed in a film forming mechanism S14. The upper phase shift layer forming step uses a target S14b having a molybdenum to silicon ratio within a predetermined range. The upper phase shift layer forming step may use a target S14b having a predetermined composition of ingredients other than molybdenum and silicon. It is also preferable to appropriately select a target S14b having a different composition. The upper phase shift layer forming step sets film forming conditions for the upper phase shift layer 12b.

[0113] Similarly, the light-shielding layer forming step forms the light-shielding layer 13 on the upper phase shift layer 12b. The light-shielding layer forming step is performed in a film-forming mechanism S15. The light-shielding layer forming step uses a target S15b containing chromium. The light-shielding layer forming step sets film-forming conditions for the light-shielding layer 13.

[0114] The method for manufacturing a phase shift mask blank may include, in addition to the phase shift layer forming step and the light-shielding layer forming step, a lamination step for laminating an etching stop layer, a protective layer, an adhesion layer, a chemical-resistant layer, an anti-reflection layer, etc., to the phase shift mask blank 10B. In this case, the film can be formed by sputtering under sputtering conditions such as a corresponding target and gas, or by stacking the film by other film forming methods to form the phase shift mask blank 10B of this embodiment.

[0115] A method for manufacturing a phase shift mask 10 from the phase shift mask blank 10B of this embodiment will be described below.

[0116] 4 to 8 are cross-sectional views showing the steps of the method for manufacturing the phase shift mask according to this embodiment. Fig. 9 is a cross-sectional view showing the phase shift mask according to this embodiment. Phase shift mask (photomask) 10 in this embodiment is manufactured from phase shift mask blank 10 B. Phase shift mask 10 has a pattern formed in phase shift layer 12 and light-shielding layer 13, as shown in FIG.

[0117] The method for manufacturing phase shift mask 10 includes a resist pattern forming step, a first etching step, a second etching step, and a third etching step, and may further include a cleaning step corresponding to each step.

[0118] In the resist pattern forming step, first, a photoresist layer 15 is formed on the outermost surface of a phase shift mask blank 10B, as shown in Fig. 4. In the resist pattern forming step, a phase shift mask blank 10B having a photoresist layer 15 formed on its outermost surface in advance may be prepared. The photoresist layer 15 may be either positive or negative. The photoresist layer 15 is compatible with etching of so-called chromium-based materials and molybdenum silicide-based materials. The photoresist layer 15 is a liquid resist. The photoresist layer 15 is applied by a coating process.

[0119] In the resist pattern forming step, the photoresist layer 15 is exposed and developed. As a result, in the resist pattern forming step, a resist pattern 15P1 is formed on the surface of the light-shielding layer 13 that is farther from the glass substrate 11 than the phase shift layer 12, as shown in FIG. 5 . The resist pattern 15P1 functions as an etching mask for the light-shielding layer 13 and the phase shift layer 12. In this embodiment, the resist pattern is formed only once.

[0120] In the resist pattern forming step, the shape of the resist pattern 15P1 is determined appropriately depending on the etching pattern of the light-shielding layer 13 and the phase shift layer 12. In the resist pattern forming step, the resist pattern is set to a shape having an opening width corresponding to the opening width dimension of the light-transmitting region 10L (see FIGS. 7 and 8).

[0121] After the resist pattern forming step is completed, the first etching step is then performed. The first etching step is a first light-shielding pattern forming step. In the first light-shielding pattern forming step, the light-shielding layer 13 is etched through the resist pattern 15P1. In the first light-shielding pattern forming step, the light-shielding layer 13 is wet-etched using a first etching solution. In the first light-shielding pattern forming step, a first light-shielding pattern 13P1 is formed as shown in FIG.

[0122] In the first light-shielding pattern formation step, an etching solution for a chromium-based material is used as the first etching solution. The etching solution for the chromium-based material may be an etching solution containing cerium diammonium nitrate. The etching solution for the chromium-based material is preferably cerium diammonium nitrate containing an acid such as nitric acid or perchloric acid. The first etching solution may contain cerium diammonium nitrate (Cr etching solution manufactured by Dai Nippon Printing Co., Ltd., product name MPM-E). In the light-shielding pattern formation step, since the upper phase shift layer 12b is made of molybdenum silicide, the upper phase shift layer 12b is hardly etched by a chromium-based etching solution. Also, since the lower phase shift layer 12a is covered with the upper phase shift layer 12b, the lower phase shift layer 12a is not etched by a chromium-based etching solution.

[0123] After the first etching step is completed, a cleaning step is performed as necessary. In the cleaning step, an alkaline solution is used as a cleaning solution. The alkaline solution used may be a sodium hydroxide solution or a mixture of ammonia and hydrogen peroxide. Because the phase shift layer 12 has the upper phase shift layer 12b on its surface, the thickness of the upper phase shift layer 12b is not changed by cleaning with the alkaline solution in the cleaning step. Furthermore, because the lower phase shift layer 12a is covered by the upper phase shift layer 12b, the thickness of the lower phase shift layer 12a is not changed. Because the surface of the glass substrate 11 is not exposed, cleaning with the alkaline solution does not roughen the surface of the glass substrate 11.

[0124] Next, a second etching step is performed. The second etching step is an upper phase shift pattern forming step. In the upper phase shift pattern forming step, the upper phase shift layer 12b is etched. In the upper phase shift pattern forming step, the upper phase shift layer 12b is etched through the first light-shielding pattern 13P1 and the resist pattern 15P1. In the upper phase shift pattern forming step, wet etching is performed using an etching solution. In the upper phase shift pattern forming step, an upper phase shift pattern 12bP1 is formed, as shown in FIG. 7. The upper phase shift pattern 12bP1 has a hollowed shape that is narrower than the first light-shielding pattern 13P1.

[0125] The second etching step uses a second etching solution capable of etching the upper phase shift layer 12b made of molybdenum silicide. The upper phase shift pattern forming step uses an etching solution containing a fluorine compound and an oxidizer. The upper phase shift pattern forming step uses an etching solution containing at least one fluorine compound selected from hydrofluoric acid, hydrosilicic acid, and ammonium bifluoride. The upper phase shift pattern forming step uses an etching solution containing at least one oxidizer selected from hydrogen peroxide, nitric acid, and sulfuric acid. The second etching solution can contain hydrofluoric acid (MoSi etching solution, product name PEF-006, manufactured by Kanto Chemical Co., Inc.).

[0126] The upper phase shift layer 12b is made of a molybdenum silicide compound. The molybdenum silicide compound can be etched using, for example, a mixture of ammonium hydrogen fluoride and hydrogen peroxide. On the other hand, the chromium compound forming the light-shielding layer 13 can be etched using, for example, a mixture of ceric ammonium nitrate and perchloric acid. Similarly to the light-shielding layer 13, the chromium compound forming the unexposed lower phase shift layer 12a can be etched using, for example, a mixture of ceric ammonium nitrate and perchloric acid.

[0127] During each wet etching, the selectivity between light-shielding layer 13 and upper phase shift layer 12b becomes very large. Therefore, after first light-shielding pattern 13P1 and upper phase shift pattern 12bP1 are formed by etching, it is possible to obtain good cross-sectional shapes of phase shift mask 10 that are close to vertical.

[0128] Next, a third etching step is performed. The third etching step is a step of forming a lower phase shift pattern. At the same time, the third etching step is a step of forming a second light-shielding pattern. The third etching step etches the lower phase shift layer 12a. The third etching step etches the lower phase shift layer 12a through the upper phase shift pattern 12bP1. The third etching step is wet etching using a third etching solution. The third etching step forms a lower phase shift pattern 12aP1 as shown in FIG. 8.

[0129] The lower phase shift pattern 12aP1 has a shape with the same width as the upper phase shift pattern 12bP1. The side-etched surfaces of the lower phase shift pattern 12aP1 and the upper phase shift pattern 12bP1 are flush with each other. The cross-sectional shapes of the lower phase shift pattern 12aP1 and the upper phase shift pattern 12bP1 are perpendicular to the surface of the glass substrate 11. In other words, the cross-sectional shape of the phase shift layer 12 is perpendicular to the surface of the glass substrate 11.

[0130] The wall surfaces of the phase shift pattern 12P1 formed in the second and third etching steps have an angle (taper angle) θ that is close to a right angle with the surface of the glass substrate 11. The angle between the wall surfaces of the phase shift pattern 12P1 and the surface of the glass substrate 11 can be approximately 90°. The angle between the wall surfaces of the phase shift pattern 12P1 and the surface of the glass substrate 11 can be constant in the thickness direction.

[0131] In the third etching step, an area where the lower phase shift pattern 12aP1 is not formed is formed as the transmissive area 10L. In the transmissive area 10L, the glass substrate 11 is exposed.

[0132] At the same time, the third etching process side-etches the first light-shielding pattern 13P1. At this time, the first light-shielding pattern 13P1 is not etched in the film thickness direction because its top and bottom surfaces are in contact with the resist pattern 15P1 and the upper phase shift pattern 12bP1. The third etching process is wet etching using a third etching solution. As shown in FIG. 8, the third etching process forms a second light-shielding pattern 13P2. The second light-shielding pattern 13P2 has a hollowed-out shape that is narrower than the upper phase shift pattern 12bP1 due to the side etching.

[0133] In the third etching step, the second light-shielding pattern 13P2 is side-etched to form a phase shift region 10ps on the upper surface of the upper phase shift pattern 12bP1, where the second light-shielding pattern 13P2 is not present. The upper phase shift pattern 12bP1 is exposed in the phase shift region 10ps. The phase shift region 10ps has a width dimension W10ps. Here, the width direction means the dimension in the direction in which side etching progresses in the first light-shielding pattern 13P1 that is the target of side etching.

[0134] In the third etching step, an etching solution for a chromium-based material is used as the third etching solution, similar to the first etching step. The etching solution for the chromium-based material may be an etching solution containing cerium diammonium nitrate. For example, the etching solution for the chromium-based material is preferably cerium diammonium nitrate containing an acid such as nitric acid or perchloric acid. The third etching solution preferably has an etching rate lower than that of the first etching solution. Furthermore, the third etching solution used in the third etching step may contain nitric acid (Ni etching solution manufactured by Nippon Chemical Industry Co., Ltd., product name HA).

[0135] In the third etching step, the first light-shielding pattern 13P1 and the lower phase shift layer 12a are exposed to the etching solution for the same amount of time. The amount of side etching, by which the first light-shielding pattern 13P1 forms the second light-shielding pattern 13P2, and the amount of etching in the film thickness direction, by which the lower phase shift layer 12a forms the lower phase shift pattern 12aP1, are each set by the compositions of the light-shielding layer 13 and the lower phase shift layer 12a.

[0136] That is, the composition of the light-shielding layer 13 and the composition of the lower phase shift layer 12a are set so that the width dimension of the phase shift region 10ps and the film thickness of the lower phase shift layer 12a can be formed in the same etching time.

[0137] Specifically, the thickness W12a of the lower phase shift layer 12a, the width dimension W10ps of the phase shift region 10ps, the etching rate ER12a of the lower phase shift layer 12a, and the side etching rate SER13 of the light-shielding layer 13 are expressed as follows: W12a / W10ps=SER13 / ER12a The composition of the light-shielding layer 13 and the composition of the lower phase shift layer 12a are set so as to satisfy the following.

[0138] Alternatively, the etching rate ER12a of the lower phase shift layer 12a and the side etching rate SER13 of the light-shielding layer 13 are W12a = (SER13 / ER12a) × W10ps The thickness W12a of the lower phase shift layer 12a is set relative to the width W10ps of the phase shift region 10ps so as to satisfy the following.

[0139] As a result, in the third etching step, the side-etched surfaces of the lower phase shift pattern 12aP1 and the upper phase shift pattern 12bP1 become flush with each other. At the same time, in the third etching step, the first light-shielding pattern 13P1 is side-etched so that the phase shift region 10ps has a width dimension W10ps.

[0140] The third etching step is completed when the formation of the lower phase shift pattern 12aP1 is completed, that is, when the side-etched surface of the lower phase shift pattern 12aP1 becomes flush with the upper phase shift pattern 12bP1. The third etching step uses an etching solution containing a chromium-based material, and therefore does not damage the exposed glass substrate 11. The third etching step can reduce the influence of glass etching in the patterning process for fabricating a phase shift mask.

[0141] After the third etching step is completed, a cleaning step is carried out as necessary. This cleaning step is a resist removal step. In the cleaning step, the resist pattern 15P1 is removed as shown in FIG. The cleaning step uses a sodium hydroxide solution, a potassium hydroxide solution, and a tetramethylammonium hydroxide (TMAH) solution as cleaning solutions. In addition, because the processing time is short, the surface of the glass substrate 11 is not roughened in the light-transmitting region 10L by cleaning with an alkaline solution. Because the surface of the glass substrate 11 is not roughened in the light-transmitting region 10L, fluctuations in the phase shift characteristics can be prevented. Furthermore, because the surface of the glass substrate 11 is not roughened, it becomes easy to recycle the glass substrate 11 without undergoing a re-polishing process.

[0142] These are formed as light-transmitting regions 10L where the surface of glass substrate 11 is exposed, phase shift regions 10ps where phase shift pattern 12P1 remains and is exposed, and light-shielding regions 10b where second light-shielding pattern 13P2 remains, thereby completing the manufacture of phase shift mask 10 as shown in FIG.

[0143] In this embodiment, changes in phase shift angle, film thickness, and transmittance can be suppressed in the manufacturing process of phase shift mask 10, which uses chemicals such as acids and alkalis for pattern formation. In addition, since the surface of glass substrate 11 is not roughened, glass substrate 11 can be easily recycled without undergoing a re-polishing process.

[0144] In this embodiment, the first to third etching steps are performed without removing the resist pattern 15P1, which reduces the number of alignment tasks and steps. At the same time, in the third etching step, the first light-shielding pattern 13P1 and the lower phase shift layer 12a are simultaneously etched, which reduces the amount of etching solution used.

[0145] By setting the etching rate ER12a of the lower phase shift layer 12a and the side etching rate SER13 of the light-shielding layer 13 based on their respective compositions, and by setting the film thickness W12a of the lower phase shift layer 12a and the width dimension W10ps of the phase shift region 10ps in advance, it becomes possible to simultaneously etch the first light-shielding pattern 13P1 and the lower phase shift layer 12a in the third etching process.

[0146] The film properties of the lower phase shift layer 12a, the upper phase shift layer 12b, and the light-shielding layer 13 in this embodiment will be described below.

[0147] <Relationship between composition and etching rate> When the lower phase shift layer 12a and the light-shielding layer 13 are mainly composed of Cr, the etching rate tends to be higher when the C content is high and the O and N content is low. When the upper phase shift layer 12b is mainly composed of Si, the etching rate tends to be higher when the content of Mo and O is small and the content of N is large.

[0148] <Relationship between film thickness and side etching amount> The thicker the lower phase shift layer 12a, the greater the amount of side etching of the light-shielding layer 13.

[0149] <Relationship between maintaining optical properties and adjusting shape> To maintain the transmittance within a target range and a good cross-sectional shape, precise control of the film composition of each layer is required. Also, to maintain accurate retardation, it is preferable that the cross-sectional shape is as close to vertical as possible.

[0150] <Relationship between glass surface damage and film properties> The lower phase shift layer 12a must have a composition that is not lost by the etchant used for the upper phase shift layer 12b, and as long as this is the case, damage to the glass surface will not occur.

[0151] Specific examples of the combination of film thickness and composition for each film are shown below. <Example 1> Light-shielding layer 13: Cr, C, O, N, film thickness 70 nm to 110 nm Deposition gas: Ar, N2, CO2, Ar / CH4 Power: 8.0kW Upper phase shift layer 12b: Si, Mo, N, C, O, film thickness 100 to 130 nm Deposition gas: Ar, N2, CO2 Power: 4.0kW Lower phase shift layer 12a: Cr, C, O, N, film thickness 10 nm to 50 nm Deposition gas: Ar, N2, CO2, Ar / CH4 Power: 2.0kW

[0152] <Example 2> Light-shielding layer 13: Cr, C, O, N, film thickness 100 nm to 150 nm Deposition gas: Ar, N2, CO2, Ar / CH4 Power: 9.0kW Upper phase shift layer 12b: Si, Mo, N, thickness 100 to 130 nm Deposition gas: Ar, N2 Power: 4.0kW Lower phase shift layer 12a: Ni, Ti, C, O, N, film thickness 10 nm to 50 nm Deposition gas: Ar, N2, CO2 Power: 2.0kW

[0153] <Example 3> Light-shielding layer 13: Ni, Ti, C, O, N, film thickness 100 nm to 130 nm Deposition gas: Ar, N2, CO2 Power: 8.5kW Upper phase shift layer 12b: Cr, C, O, N, film thickness 100 nm to 130 nm Deposition gas: Ar, N2, CO2, Power: 8.0kW Lower phase shift layer 12a: Si, Mo, N, film thickness 10 nm to 50 nm Deposition gas: Ar, N2, CO2 Power: 2.0kW

[0154] As in each of these examples, it has been found that by having the above-mentioned relationships between the light-shielding layer, upper phase shift layer, and lower phase shift layer, it is possible to reduce the occurrence of damage to the transparent substrate surface and provide a phase shift mask that can be recycled without undergoing a polishing process.

[0155] Furthermore, in the present invention, it is also possible to individually select and combine the individual configurations in the above-described embodiments. [Explanation of symbols]

[0156] 10...Phase shift mask 10B...Phase shift mask blanks 10b...shading area 10L…Transmission area 10ps...phase shift region 11...Glass substrate (transparent substrate) 12...Phase shift layer 12P1...Phase shift pattern 12a...lower phase shift layer 12aP1…Lower phase shift pattern 12b...Upper phase shift layer 12bP1...Upper phase shift pattern 13...Light blocking layer 13P1...First light blocking pattern 13P2...Second light blocking pattern

Claims

1. A phase shift mask blank having a mask layer that serves as a phase shift mask, a phase shift layer laminated on a transparent substrate; a light-shielding layer laminated on the phase shift layer; and The phase shift layer comprises: a lower phase shift layer laminated on the transparent substrate; an upper phase shift layer stacked on the lower phase shift layer; and the lower phase shift layer and the light-shielding layer can be etched with the same etchant; the upper phase shift layer is etchable with an etchant different from that of the lower phase shift layer and the light-shielding layer; A phase shift mask blank characterized by:

2. a first light-shielding pattern formed by etching from the light-shielding layer and an upper phase shift pattern formed by etching from the upper phase shift layer, the first light-shielding pattern having an equal width to the upper phase shift pattern, and a lower phase shift pattern having an equal width to the upper phase shift pattern formed by etching from the lower phase shift layer to form a transparent region of the phase shift mask; a second light-shielding pattern formed by side etching from the first light-shielding pattern has a width narrower than that of the upper phase shift pattern, and can form a phase shift region of the phase shift mask; 2. The phase shift mask blank according to claim 1.

3. the thickness of the lower phase shift layer is smaller than the thickness of the light-shielding layer; 3. The phase shift mask blank according to claim 2.

4. a thickness of the lower phase shift layer is smaller than a side etching amount of the first light-shielding pattern; 4. The phase shift mask blank according to claim 3.

5. the width of the phase shift region is 4.0 to 500 times the thickness of the lower phase shift layer; 5. The phase shift mask blank according to claim 4.

6. an etching rate of the lower phase shift layer is 1 / 11 to 1 / 2.0 times the side etching rate of the light-shielding layer; 6. The phase shift mask blank according to claim 5.

7. the light-shielding layer contains chromium, the lower phase shift layer contains one or more selected from chromium, nickel, molybdenum, niobium, and titanium; the upper phase shift layer contains silicon and has etching selectivity with respect to the lower phase shift layer and the light-shielding layer; 7. The phase shift mask blank according to claim 6.

8. A phase shift mask manufactured from the phase shift mask blank according to any one of claims 2 to 6, The surface roughness of the transparent substrate in the transmission region is in the range of Ra 0.14 nm to Ra 2.5 nm. A phase shift mask characterized by:

9. 9. A method for manufacturing a phase shift mask according to claim 8, comprising the steps of: preparing a phase shift mask blank in which the lower phase shift layer, the upper phase shift layer, and the light-shielding layer formed on the transparent substrate are laminated; a first etching step of forming the first light-shielding pattern from the light-shielding layer by wet etching using a first etching solution, using a resist pattern formed by laminating on the light-shielding layer as a mask; a second etching step of forming the upper phase shift pattern from the upper phase shift layer by wet etching using at least the etched first light-shielding pattern as a mask and a second etching liquid different from the first etching liquid; a third etching step of forming a second light-shielding pattern from the first light-shielding pattern by side etching using a third etching solution that is the same as the first etching solution, using at least the resist pattern as a mask, and simultaneously forming a lower phase shift pattern from the lower phase shift layer by wet etching; and the resist pattern is not peeled off in the first etching step, the second etching step, and the third etching step; 10. A method for manufacturing a phase shift mask, comprising:

10. In the second etching step, the first light-shielding pattern and the upper phase shift pattern are formed to have the same width; In the third etching step, The upper phase shift pattern and the lower phase shift pattern are formed to have the same width to form the transmission region; the second light-shielding pattern is formed to have a width narrower than that of the upper phase shift pattern to form the phase shift region; 10. The method for manufacturing a phase shift mask according to claim 9.

11. the first etching solution includes ceric ammonium nitrate; the second etching solution contains hydrofluoric acid; the third etching solution contains ceric ammonium nitrate; 11. The method for manufacturing a phase shift mask according to claim 10.

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