Photomask blank, photomask, method for manufacturing photomask blank, method for manufacturing photomask, and method for manufacturing device

Abstract

The photomask blank has a first layer and a second layer on a substrate, the first layer is on the substrate, the second layer is on the first layer, and the first layer contains zirconium in an atomic composition percentage (atomic%) of 60% to 99.5% (inclusive).

Description

Technical Field

[0001] The present invention relates to a photomask blank, a photomask, a method for manufacturing a photomask blank, a method for manufacturing a photomask, and a method for manufacturing a device. The present invention claims priority from Japanese Patent Application No. 2023-040414, filed on March 15, 2023, and the contents of that application are incorporated by reference into this application in designated countries that permit incorporation by reference. Background Art

[0002] A halftone mask blank in which the material of the halftone layer and the material of the binary layer are the same is known. Such a halftone mask blank requires a stopper layer (etching stopper) to be provided between the halftone layer and the binary layer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-189281 Summary of the Invention

[0006] One embodiment of the present invention is a photomask blank comprising a first layer and a second layer on a substrate, wherein the first layer is on the substrate, the second layer is on the first layer, and the first layer contains zirconium at an atomic composition percentage (atomic %) of 60% to 99.5%. Another embodiment of the present invention is a photomask blank comprising a first layer and a second layer on a substrate, wherein the first layer is on the substrate, the second layer is on the first layer, the first layer is a halftone layer containing a metal different from chromium, the difference between the transmittance of light having a wavelength of 365 nm through the first layer and the transmittance of light having a wavelength of 436 nm through the first layer is 1.5% or less, and the second layer is a binary layer containing chromium.

[0007] Another aspect of the present invention is a photomask including the above-mentioned photomask blank on which a pattern is formed.

[0008] Another embodiment of the present invention is a method for manufacturing a photomask, comprising: a first step of etching the second layer of the photomask blank to form a second layer pattern on the second layer; and a second step of etching the first layer to form a first layer pattern different from the second layer pattern on the first layer.

[0009] Another embodiment of the present invention is a method for manufacturing a photomask blank, which is a method for manufacturing a photomask blank for forming a first layer and a second layer on a substrate, comprising: a first layer film forming step, forming the first layer on the substrate while introducing gas; and a second layer film forming step, forming the second layer on the first layer, wherein the proportion of nitrogen in the gas is calculated as a flow percentage (flow %) and is greater than 0% and less than 3%.

[0010] Another embodiment of the present invention is a method for manufacturing a photomask using the photomask blank manufactured by the above-mentioned method for manufacturing a photomask blank.

[0011] Another embodiment of the present invention is a method for manufacturing a device, including an exposure step of exposing a workpiece to a pattern using a photomask manufactured by the above-described method for manufacturing a photomask. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic cross-sectional view showing an example of the photomask blank according to the present embodiment.

[0013] Figure 2 This is a schematic cross-sectional view showing a photomask according to this embodiment.

[0014] Figure 3 Steps A to E in FIG. 1 are diagrams illustrating a method for manufacturing a photomask according to this embodiment.

[0015] Figure 4 This is a schematic diagram of an exposure apparatus used in the exposure method of this embodiment.

[0016] Figure 5 It is a schematic diagram of an example of the manufacturing apparatus of the photomask blank which shows this embodiment.

[0017] Figure 6 This graph shows the transmittance at wavelengths of 300 nm to 800 nm of Zr-based halftone layers having different film thicknesses, which were produced using a 2% N 2 gas ratio (flow %).

[0018] Figure 7 This is a graph showing the transmittance of a Zr-based halftone layer having a N content (atomic %) of 0 to 41.8% at a wavelength of 300 nm to 800 nm.

[0019] Figure 8 This graph shows the transmittance of a MoSi-based halftone layer produced with an N 2 gas ratio (flow %) of 0 to 50% at a wavelength of 300 nm to 800 nm.

[0020] Figure 9 This is a graph showing the transmittance flatness of a Zr-based halftone layer having a N content (atomic %) of 0 to 41.8%. DETAILED DESCRIPTION

[0021] The following describes an embodiment of the present invention (hereinafter referred to as "this embodiment"). The following embodiment is an example for illustrating the present invention and is not intended to limit the present invention to the following content. The present invention can be implemented by appropriately modifying it within the scope of its main points.

[0022] like Figure 1 As shown, the photomask blank 100 of this embodiment includes: a substrate 10; a halftone layer 20 (semi-transmissive film) including a zirconium compound formed on the surface of the substrate 10; and a binary layer 30 (light-shielding film) including a chromium compound formed on the halftone layer 20.

[0023] like Figure 2 As shown, the binary layer 30 of the photomask blank 100 is etched to form a binary layer pattern 50 (first step), and then the halftone layer 20 is etched to form a halftone layer pattern 51, thereby forming the photomask 200 of this embodiment. The photomask 200 is used when manufacturing display devices such as FPDs (Flat Panel Displays) and semiconductor devices such as LSIs (Large Scale Integration).

[0024] [Structures of Photomask Blank 100 and Photomask 200]

[0025] The material of the substrate 10 is, for example, synthetic quartz glass, and any material that can sufficiently transmit the exposure light of an exposure device using the photomask 200 is sufficient.

[0026] The halftone layer 20 is a semi-transparent light-shielding film preferably containing a metal, particularly preferably zirconium (Zr). When containing zirconium, the zirconium content, in terms of atomic percentage (atom %), is 60% to 99.5%. The lower limit of this content is preferably 65%, more preferably 70%, and even more preferably 75%. The upper limit of this content is preferably 97%, more preferably 94%, and even more preferably 91%.

[0027] Furthermore, the halftone layer 20 preferably contains nitrogen (N). When nitrogen is contained, the nitrogen content, in terms of atomic percentage (atom %), is between 0% and 30%. The lower limit of this content is preferably 5%, more preferably 10%, and even more preferably 15%. The upper limit of this content is preferably 27%, more preferably 24%, and even more preferably 21%.

[0028] In addition to the above-mentioned zirconium and nitrogen, the halftone layer 20 may also contain other metals or silicon, or contain a small amount of impurities to the extent that it does not affect the effect. However, it is ideal that the halftone layer 20 does not contain the metal atoms contained in the binary layer 30.

[0029] The transmittance of light having a wavelength of 365 nm to 436 nm through the halftone layer 20 is not particularly limited and can be appropriately set, for example, 5% to 50%.

[0030] The halftone layer 20 exhibits transmittance flatness for light with a wavelength range of 365 nm to 436 nm. As used herein, transmittance flatness refers to the property that transmittance is less likely to change even when the wavelength of light changes. The difference between the transmittance of light with a wavelength of 365 nm and the transmittance of light with a wavelength of 436 nm passing through the halftone layer 20 is 1.5% or less. The upper limit of this transmittance difference is preferably 1.0%, more preferably 0.5%, and even more preferably 0%. By ensuring that the halftone layer 20 exhibits such transmittance flatness, exposure can be performed while suppressing changes in transmittance even when the wavelength of the exposure light varies.

[0031] Furthermore, the difference between the maximum and minimum values ​​of the transmittance of light with a wavelength of 365 nm, the transmittance of light with a wavelength of 405 nm, and the transmittance of light with a wavelength of 436 nm through the halftone layer 20 may be 1.5% or less. The upper limit of this transmittance difference is preferably 1.0%, more preferably 0.5%, and even more preferably 0%.

[0032] The difference between the maximum and minimum transmittances of light in the wavelength range of 365 nm to 436 nm passing through the halftone layer 20 may be 1.5% or less. The upper limit of the transmittance difference is preferably 1.0%, more preferably 0.5%, and even more preferably 0%.

[0033] From the viewpoint of improving transmittance flatness, the thickness of the halftone layer 20 is 5 nm to 45 nm. The lower limit of the thickness is preferably 8 nm, more preferably 11 nm.

[0034] The binary layer 30 is a layer located on the halftone layer 20 and functions as a light-shielding film.

[0035] The binary layer 30 preferably contains metal atoms, and particularly preferably contains chromium (Cr). The chromium content in the case of containing chromium is not particularly limited and can be appropriately set. Furthermore, it is preferred that chromium be contained in the form of, for example, chromium nitride or chromium oxide. The binary layer 30 may also contain other metals besides chromium, or contain a small amount of impurities to the extent that the effect is not affected. However, it is ideal that the binary layer 30 does not contain the metal atoms contained in the halftone layer 20.

[0036] During the manufacture of photomask 200, photoresist layers 40 and 41 are exposed to light with a bright line wavelength of 365 nm to 436 nm. Therefore, the binary layer 30 disposed below the photoresist layers 40 and 41 preferably has a low reflectivity for light with a bright line wavelength of 365 nm to 436 nm. By suppressing the reflection of the exposure light, multiple reflections of the exposure light within the photoresist layers 40 and 41 are suppressed, thereby improving the pattern accuracy of photomask 200. For example, the reflectivity of binary layer 30 for light with a wavelength of 413 nm is preferably 15% or less. Binary layer 30 can be a single layer or can be formed from two or more layers. When binary layer 30 is formed from two or more layers, the layer directly below the photoresist layers 40 and 41 preferably has a low reflectivity for the exposure light. For example, binary layer 30 can be composed of a chromium nitride layer formed on the halftone layer 20 and a chromium oxide layer formed further on the chromium nitride layer. The chromium oxide layer can suppress the reflectivity of light having a wavelength of 413 nm to approximately 11%, for example.

[0037] The thickness of the binary layer 30 is not particularly limited and can be adjusted appropriately. For example, it can be set to 10 nm or more and 120 nm or less.

[0038] [Method of Manufacturing Photomask Blank 100]

[0039] The method for manufacturing the photomask blank 100 is not particularly limited, and a general method can be used. For example, the photomask blank 100 can be manufactured using the method described below. Figure 5 The halftone layer 20 and the binary layer 30 are formed on the substrate 10 by reactive sputtering as described in the embodiment.

[0040] Figure 5 Schematic diagram showing a manufacturing apparatus 500 for the photomask blank 100 according to the present embodiment, and showing the interior of the manufacturing apparatus 500 as viewed from above. Figure 5 The manufacturing apparatus 500 shown is an in-line sputtering apparatus, which includes: an inlet chamber 501 for loading a substrate 10 for manufacturing a photomask blank 100, a first sputtering chamber 502, a buffer chamber 503, a second sputtering chamber 504, and an outlet chamber 505 for unloading the manufactured photomask blank 100.

[0041] The substrate tray P is a frame-shaped tray capable of placing the substrate 10 for forming the halftone layer 20 and the binary layer 30. The substrate 10 is placed on the substrate tray P with the surface, i.e., the surface on which the halftone layer 20 and the binary layer 30 are formed, facing downward. In the manufacturing apparatus 500, as will be described later, the substrate 10 is placed along the target while the surface is kept facing the target. Figure 5 The substrate tray P carrying the substrate 10 is conveyed to the position of the buffer chamber 503 in the direction indicated by the solid arrow Q, so that the halftone layer 20 is formed on the surface of the substrate 10 .

[0042] Thereafter, as indicated by a dotted arrow R, the substrate tray P is transported from the buffer chamber 503 to the position of the unloading chamber 505 , whereby the binary layer 30 is formed on the halftone layer 20 , thereby manufacturing the photomask blank 100 .

[0043] The loading chamber 501, the first sputtering chamber 502, the buffer chamber 503, the second sputtering chamber 504, and the unloading chamber 505 are each separated by a partition member (not shown). The loading chamber 501, the first sputtering chamber 502, the buffer chamber 503, the second sputtering chamber 504, and the unloading chamber 505 are each connected to an exhaust device (not shown) to exhaust the interior of each chamber.

[0044] A first target 506 is disposed within the first sputtering chamber 502, and a second target 507 is disposed within the second sputtering chamber 504. The first target 506 is preferably made of a metal such as zirconium, and the second target 507 is preferably made of a metal such as chromium. A DC power supply (not shown) is provided in each of the first sputtering chamber 502 and the second sputtering chamber 504 to supply power to the first target 506 and the second target 507, respectively.

[0045] A first gas inlet 508 for introducing a sputtering gas into the first sputtering chamber 502 is provided in the first sputtering chamber 502. For example, the first target 506 is a sputtering target for forming a Zr-based film, and is formed of a material containing zirconium (Zr). Specifically, the first target 506 is formed of a material selected from zirconium, zirconium oxide, zirconium nitride, zirconium carbide, and the like. For example, the sputtering gas introduced through the first gas inlet 508 is a gas for forming a Zr-based film, and an inert gas (argon, etc.) or a mixed gas of a gas containing nitrogen and an inert gas (argon, etc.) can be selected. In this case, the proportion of nitrogen in the sputtering gas (N2 gas ratio) can be 0 to 3% in terms of flow rate percentage (flow rate %).

[0046] The second sputtering chamber 504 is provided with a second gas inlet 509 for introducing a sputtering gas into the second sputtering chamber 504. For example, the second target 507 is a sputtering target for forming a chromium compound layer and is formed from a material containing chromium. Specifically, the second target 507 is formed from a material selected from chromium, chromium oxide, chromium nitride, chromium carbide, and the like. For example, the sputtering gas introduced through the second gas inlet 509 is a gas for forming a Cr-based film and can be an inert gas (such as argon) or a mixed gas of a gas containing nitrogen or oxygen and an inert gas (such as argon).

[0047] When the substrate 10 is transported to the first sputtering chamber 502, a halftone layer 20 is formed on the surface of the substrate 10 by sputtering in the first sputtering chamber 502. In addition, the substrate 10 formed with the halftone layer 20 can be transported between the buffer chamber 503 and the loading chamber 501 (solid arrow Q) more than twice, and sputtered more than twice in the first sputtering chamber 502, so that the halftone layer 20 is laminated. Thereafter, the substrate 10 is transported to the second sputtering chamber 504. In the second sputtering chamber 504, a binary layer 30 is formed on the surface of the halftone layer 20 by sputtering. As with the halftone layer 20, the binary layer 30 can also be transported between the buffer chamber 503 and the unloading chamber 505 (dashed arrow R) more than twice, and sputtered more than twice in the second sputtering chamber 504, so that the binary layer 30 is laminated. In this manner, the halftone layer 20 and the binary layer 30 are sequentially formed on the surface of the substrate 10 , thereby manufacturing the photomask blank 100 .

[0048] The materials of the first target 506 and the second target 507, as well as the types of gases introduced from the first gas inlet 508 and the second gas inlet 509, can be appropriately selected according to the metal material and composition used. The first target 506 and the second target 507 are preferably made of different materials. For example, by making the binary layer 30 and the halftone layer 20 of different materials, it is unnecessary to provide an etching stopper between the binary layer 30 and the halftone layer 20. Furthermore, the first target is preferably zirconium, and the second target is preferably chromium. Sputtering can be performed using any of DC sputtering, RF sputtering, and ion beam sputtering.

[0049] [Method of Manufacturing Photomask 200]

[0050] The method for manufacturing the photomask 200 is not particularly limited, and a general method can be used. For example, the photomask 200 can be manufactured by using the photomask blank 100 through reactive sputtering and wet etching as described in the embodiments described later (see Figure 3 Furthermore, when the photomask 200 is manufactured using the photomask blank 100 in which the halftone layer 20 and the binary layer 30 are made of different materials, the side etching amount of the halftone layer 20 does not need to be considered when etching the binary layer 30 .

[0051] Figure 3 1 and 2 are diagrams illustrating a method for manufacturing the photomask 200 of the present embodiment. A method for forming the pattern 50 on the binary layer 30 and the pattern 51 on the halftone layer 20 of the photomask blank 100 will be described below.

[0052] Process 1

[0053] A photoresist layer 40 ( Figure 3 : Step A) The thickness of the photoresist layer 40 is not particularly limited and can be set appropriately.

[0054] The photoresist layer 40 is exposed using a light-shielding mask having an opening corresponding to the pattern 50. As a result, a portion of the photoresist layer 40 corresponding to the pattern 50 is exposed.

[0055] The photoresist layer 40 having an opening corresponding to the pattern 50 is used as a mask, and the binary layer 30 is wet-etched using a first etching solution, thereby forming the pattern 50 ( Figure 3 : Step B). The etching temperature and etching time are not particularly limited and can be set appropriately. Thereafter, the photoresist layer 40 is stripped.

[0056] The first etching solution is different from the second etching solution described below and is preferably an etching solution containing ammonium cerium nitrate and nitric acid.

[0057] Second process

[0058] Next, a photoresist layer 41 ( Figure 3 : Step C) The thickness of the photoresist layer 41 is not particularly limited and can be set appropriately.

[0059] The photoresist layer 41 is exposed using a light-shielding mask having an opening corresponding to the pattern 51. As a result, a portion of the photoresist layer 41 corresponding to the pattern 51 is exposed.

[0060] The photoresist layer 41 and the binary layer 30 are used as masks, and the halftone layer 20 is wet-etched using the second etching solution, thereby forming a pattern 51 ( Figure 3 Step D). The etching temperature and etching time are not particularly limited and can be set as appropriate. It should be noted that overetching may be performed to uniformly remove the exposed halftone layer 20 without leaving any residue. For example, in the case of a 20% overetch, the time required to remove the halftone layer 20 is used as the reference time, and etching is performed for 120% of the reference time.

[0061] The second etching solution is different from the above-mentioned first etching solution and is preferably an etching solution containing ammonium fluoride.

[0062] Finally, the photoresist layer 41 is stripped to produce the photomask 200 ( Figure 3 : Step E).

[0063] [Purpose of Photomask 200]

[0064] Exposure method

[0065] The exposure method using the photomask 200 can be implemented as a photolithography process using an exposure apparatus in the manufacture of devices such as semiconductors and liquid crystal panels.

[0066] like Figure 4 As shown, the exposure device 400 used in the exposure method includes: a light source LS; an illumination optical system 402; a mask stage 403 holding a photomask 200; a projection optical system 404; a substrate stage 405 holding a photosensitive substrate 415 as an exposure object; and a drive mechanism 406 for moving the substrate stage 405 in a horizontal plane.

[0067] First, a photomask 200 is placed on the mask stage 403 of the exposure device 400. Furthermore, a photosensitive substrate 415 coated with photoresist is placed on the substrate stage 405. Then, exposure light is emitted from the light source LS. The emitted exposure light enters the illumination optical system 402, where it is adjusted into a predetermined beam and then irradiated onto the photomask 200 held on the mask stage 403. The light passing through the photomask 200 has a pattern identical to the device patterns 50 and 51 depicted on the photomask 200. This pattern is projected by the projection optical system 404 onto a predetermined position of the photosensitive substrate 415 held on the substrate stage 405. As a result, the photosensitive substrate 415 is exposed to light at a predetermined magnification according to the device pattern of the photomask 200.

[0068] The photomask 200 of this embodiment has high pattern accuracy. Therefore, by performing exposure using the photomask 200 , circuit pattern defects in the exposure process can be reduced, and highly integrated devices can be manufactured efficiently.

[0069] Furthermore, by using the halftone layer 20 as a phase shift layer, the photomask blank 100 can be used as a phase shift mask blank, and the photomask 200 can be used as a phase shift mask.

[0070] Example

[0071] Hereinafter, the photomask blank and the photomask will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples and Comparative Examples.

[0072] [Manufacturing of Photomask Blank 100]

[0073] By the following steps, the halftone layer 20 and the binary layer 30 are sequentially formed on the substrate 10 to produce the following Figure 1 A photomask blank 100 is shown.

[0074] Examples 1 to 3

[0075] A circular parallel plate made of quartz glass (size: 3 inches in diameter, 0.5 mm thick) was prepared as the substrate 10. Using a DC magnetron sputtering apparatus (ILC-702 Canon ANELVA), a Zr alloy target (Zr purity 99.9%) was used as the sputtering target. While introducing an Ar-N2 mixed gas at a 2% N2 gas ratio (flow %), reactive sputtering was performed such that the N content (atomic %) of the halftone layer 20 became 18.5% and the film thickness became 36.3 nm, 21.5 nm, and 11.7 nm. A Zr-based halftone layer (Table 1, Table 2) was formed on the substrate 10 to form the halftone layer 20. Figure 6 The pressure in the chamber is 0.2 Pa to 1.0 Pa, and the target applied power is 0.5 kW.

[0076] Examples 4 to 7, Comparative Examples 1 to 3

[0077] A circular parallel plate made of quartz glass (size: 3 inches in diameter, 0.5 mm in thickness) was prepared as the substrate 10. Using a DC magnetron sputtering apparatus (ILC-702 Canon ANELVA), a Zr alloy target (Zr purity 99.9%) was used as the sputtering target. While introducing Ar gas or Ar-N2 mixed gas at the N2 gas ratio (flow rate %) shown in Table 2, reactive sputtering was performed to form a Zr-based halftone layer 20 (Table 2, Table 2) on the substrate 10 to form the halftone layer 20 at film thicknesses of 42.0 nm, 20.9 nm, 21.5 nm, 24.0 nm, 18.0 nm, 8.7 nm, and 8.4 nm, respectively. Figure 7 The pressure in the chamber is 0.2 Pa to 1.0 Pa, and the target applied power is 0.5 kW.

[0078] Comparative Examples 4 to 7

[0079] A circular parallel plate made of quartz glass (size: 3 inches in diameter, 0.5 mm thick) was prepared as the substrate 10. Using a DC magnetron sputtering apparatus (ILC-702 Canon ANELVA), a MoSi alloy target (atomic ratio: Mo:Si = 1:4) was used as the sputtering target. While introducing Ar gas or an Ar-N2 mixed gas at the N2 gas ratio (flow %) shown in Table 3, reactive sputtering was performed to form a MoSi-based halftone layer 20 having a film thickness of 10.1 nm, 38.3 nm, 47.7 nm, and 69.6 nm on the substrate 10 (Table 3, Figure 8 The pressure in the chamber is 0.2 Pa to 1.0 Pa, and the target applied power is 0.5 kW.

[0080] On the halftone layer 20 formed as described above, reactive sputtering was performed using a DC magnetron sputtering device (ILC-702 Canon ANELVA) using a Cr target as a sputtering target while introducing Ar gas or Ar-N2 mixed gas at the N2 gas ratio (flow %) shown in Tables 1 and 2. In this way, a binary layer 30 was formed on the halftone layer 20, and the photomask blank 100 ( Figure 1 ).

[0081] [Manufacturing of Photomask 200]

[0082] For the above-mentioned photomask blank 100, as described below, a pattern 50 is formed on the binary layer 30, and a pattern 51 is formed on the halftone layer 20. Figure 3 The steps shown are as follows: Figure 2 Photomask 200 is shown.

[0083] Process 1

[0084] First, a positive ultraviolet resist (GRX-M237 manufactured by Nagase ChemteX) was applied by spin coating on the photomask blank 100 to form a photoresist layer 40 ( Figure 3 : Step A). ​​The thickness of the photoresist layer 40 is 660 nm.

[0085] The photoresist layer 40 is exposed using a mask aligner (PLA-501 manufactured by Canon) using a high-pressure mercury lamp, using a light-shielding mask having openings corresponding to the pattern 50. As a result, the portion of the photoresist layer 40 corresponding to the pattern 50 is exposed.

[0086] The exposed photomask blank 100 is immersed in an organic alkaline developer (manufactured by Tama Chemical Industry, 1.83% tetramethylammonium hydroxide). As a result, the photosensitive portion of the photoresist layer 40 is dissolved and removed, forming an opening corresponding to the pattern 50. The photoresist layer 40 having an opening corresponding to the pattern 50 is used as a mask, and the binary layer 30 is wet-etched using the first etching solution containing ammonium cerium nitrate and nitric acid (manufactured by Hayashi Pure Chemical Industries, PureEtchCR 101). The etching solution temperature is 23±3°C, and the etching time is 80 seconds. As a result, the exposed portion of the binary layer 30 that is not covered by the photoresist layer 40 is removed to form the pattern 50 ( Figure 3 : Step B) The photoresist layer 40 is stripped using a resist stripping liquid (manufactured by Kao, CLEANTHROUGH KS-7008B).

[0087] Second process

[0088] Next, a positive ultraviolet resist (GRX-M237 manufactured by Nagase ChemteX) was applied on the uppermost layer by spin coating to form a photoresist layer 41 ( Figure 3 : Step C). The thickness of the photoresist layer 41 is 660 nm.

[0089] The photoresist layer 41 is exposed using a mask aligner (PLA-501 manufactured by Canon) using a high-pressure mercury lamp, using a light-shielding mask having openings corresponding to the pattern 51. As a result, the portion of the photoresist layer 41 corresponding to the pattern 51 is exposed.

[0090] The photosensitive portion of the photoresist layer 41 is removed, and the halftone layer 20 is wet-etched using a second etchant containing ammonium fluoride (ADEKA CHELUMICA WGM-155) using the photoresist layer 41 and the binary layer 30 as a mask. The etchant temperature is set at 23±3°C, and 20% overetching is performed to remove the exposed halftone layer 20 evenly without leaving any residue. Thus, a pattern 51 ( Figure 3 : Step D). Finally, the photoresist layer 41 is stripped using a resist stripping solution (manufactured by Kao, CLEANTHROUGH KS-7008B). Figure 3 The photomask 200 is shown in step E.

[0091] [Evaluation of Physical Properties of Halftone Layer 20]

[0092] The film thickness and transmittance of the halftone layer 20 of each example and each comparative example were measured. The difference between the transmittance of the measured light at a wavelength of 365 nm and the transmittance of the light at a wavelength of 436 nm was calculated as a value indicating the transmittance flatness. The measurement results are shown in Tables 1 to 3. Figures 6 to 9 It should be noted that the transmittance is the external transmittance that also takes reflection into account.

[0093] [Table 1]

[0094]

[0095] [Table 2]

[0096]

[0097] [Table 3]

[0098]

[0099] As shown in Table 1, Table 2 and Figure 9As shown in Table 3, good transmittance flatness was observed when the film was formed with an N2 gas ratio (flow %) of 0 to 3%. In addition, as shown in Table 3, good transmittance flatness was not observed when the MoSi-based halftone layer was formed with any N2 gas ratio (flow %).

[0100] Industrial Applicability

[0101] By making the halftone layer from a different material than the binary layer, the conventional etch stopper is no longer required. Therefore, the etch stopper film formation step is no longer necessary during the film formation process, and the etch stopper processing step is no longer necessary during the mask manufacturing process, shortening the process.

[0102] Explanation of symbols

[0103] 10 substrates

[0104] 20 halftone layers

[0105] 30 binary layers

[0106] 40 first photoresist layer

[0107] 41 second photoresist layer

[0108] 50 binary layer patterns

[0109] 51 Halftone Layer Patterns

[0110] 100 photomask blanks

[0111] 200 photomasks

[0112] 400 exposure device

[0113] LS light source

[0114] 402 lighting optical system

[0115] 404 projection optical system

[0116] 403 mask stage

[0117] 405 substrate table

[0118] 500 manufacturing equipment

[0119] P substrate tray

[0120] Q solid arrow

[0121] R dashed arrow

[0122] 501 move-in room

[0123] 502 No. 1 Sputtering Chamber

[0124] 503 buffer room

[0125] 504 No. 2 Sputtering Chamber

[0126] 505 Moving Out Room

[0127] 506 Target 1

[0128] 507 Target 2

[0129] 508 1st gas inlet

[0130] 509 Second gas inlet

Claims

1. A photomask blank comprising a first layer and a second layer on a substrate, The first layer is provided on the substrate, The second layer is provided on the first layer, The first layer contains zirconium at an atomic composition percentage (atomic %) of 60% to 99.5%.

2. The photomask blank according to claim 1, wherein The first layer is a halftone layer, The second layer is a binary layer.

3. The photomask blank according to claim 2, wherein The difference between the transmittance of light having a wavelength of 365 nm transmitted through the first layer and the transmittance of light having a wavelength of 436 nm transmitted through the first layer is 1.5% or less.

4. The photomask blank according to claim 3, wherein The transmittance is the external transmittance.

5. The photomask blank according to any one of claims 1 to 4, wherein The second layer contains chromium.

6. A photomask blank comprising a first layer and a second layer on a substrate, The first layer is provided on the substrate, The second layer is provided on the first layer, The first layer is a halftone layer containing a metal different from chromium, and the difference between the transmittance of light having a wavelength of 365 nm and the transmittance of light having a wavelength of 436 nm passing through the first layer is 1.5% or less. The second layer is a binary layer and contains chromium.

7. The photomask blank according to claim 6, wherein The transmittance is the external transmittance.

8. The photomask blank according to claim 6 or 7, wherein: The first layer contains zirconium.

9. The photomask blank according to claim 8, wherein The first layer contains zirconium at an atomic composition percentage (atomic %) of 60% to 99.5%.

10. The photomask blank according to any one of claims 1 to 9, wherein The first layer contains nitrogen.

11. The photomask blank according to claim 10, wherein The first layer contains nitrogen at an atomic composition percentage (atom %) of 0% to 30%.

12. The photomask blank according to any one of claims 1 to 11, wherein The transmittance of light having a wavelength of 365 nm to 436 nm that passes through the first layer is 5% or more and 50% or less.

13. The photomask blank according to any one of claims 1 to 12, wherein The second layer is formed so as to be in contact with the first layer.

14. The photomask blank according to any one of claims 1 to 13, wherein The thickness of the first layer is not less than 5 nm and not more than 45 nm.

15. The photomask blank according to any one of claims 1 to 14, wherein The first layer serves as a phase shift layer. 16 . A photomask comprising the photomask blank according to claim 1 , wherein a pattern is formed thereon.

17. A method for manufacturing a photomask, comprising: A first step of etching the second layer of the photomask blank according to any one of claims 1 to 15 to form a second layer pattern on the second layer; as well as In the second step, the first layer is etched to form a first layer pattern different from the second layer pattern on the first layer.

18. The method for manufacturing a photomask according to claim 17, wherein: In the first step, the second layer is etched using a first etching solution to form the second layer pattern on the second layer. In the second step, the first layer is etched using a second etching solution different from the first etching solution to form the first layer pattern on the first layer.

19. A method for manufacturing a photomask blank, comprising forming a first layer and a second layer on a substrate, the method comprising: a first layer film forming step of forming a first layer on the substrate while introducing gas; as well as a second layer forming step of forming a second layer on the first layer; The ratio of nitrogen in the gas is not less than 0% and not more than 3% in terms of flow rate percentage (flow rate %).

20. The method for manufacturing a photomask blank according to claim 19, wherein: In the second layer forming step, the second layer is formed on the first layer so as to be in contact with the first layer.

21. The method for manufacturing a photomask blank according to claim 19 or 20, wherein: The first layer comprises a metal different from chromium, The second layer contains chromium.

22. The method for manufacturing a photomask blank according to any one of claims 19 to 21, wherein: The first layer contains zirconium at an atomic composition percentage (atomic %) of 60% to 99.5%.

23. The method for manufacturing a photomask blank according to any one of claims 19 to 22, wherein: The first layer serves as a phase shift layer.

24. The method for manufacturing a photomask blank according to any one of claims 19 to 23, wherein: The first layer is a halftone layer, The second layer is a binary layer. 25 . A method for manufacturing a photomask, comprising using the photomask blank manufactured by the method for manufacturing a photomask blank according to claim 19 .

26. A method for manufacturing a device, comprising: In the exposure step, the workpiece is exposed to a pattern using the photomask manufactured by the method for manufacturing a photomask according to any one of claims 17, 18, or 25.

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