Mask blank and photo mask for use with this mask blank

Abstract

A mask blank (100) comprising: a transparent substrate (10); a phase-shift film (20) arranged on the transparent substrate (10); and a light-protective film (30) arranged on the phase-shift film (20); wherein the phase-shift film (20) comprises a phase-difference setting layer (21) and a protective layer (22) arranged on the phase-difference setting layer (21), wherein the phase-shift film (20) contains a transition metal, silicon, oxygen, and nitrogen, wherein the phase-difference setting layer comprises nitrogen in an amount of 40 to 60 atomic percent, wherein the protective layer (22) comprises nitrogen in an amount of 20 to 40 atomic percent, wherein the protective layer (22) comprises a region in which the ratio of nitrogen content to oxygen content in the thickness direction is 0.4 to 2, and the region has a thickness of 30 to 80 percent compared to the total thickness of the protective layer (22), wherein a TFT1 value of 0,25 µm / 100 °C or less, where TFT1 = ΔPMT2 − T1, where, when the thermal change of the machined mask blank (100) formed by machining the thickness of the transparent substrate (10) of the mask blank (100) to 0.6 mm and removing the light-protective film (30) is analyzed in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer is increased from T1 to T2, and ΔPM is a change in position of the upper surface of the phase-shift film (20) in the thickness direction at T2, based on a position of the upper surface of the phase-shift film (20) at T1.

Description

1. Area

[0001] The present disclosure relates to a mask blank and a photomask that uses this mask. 2. Description of the related prior art

[0002] Due to the high integration of semiconductor devices and similar materials, miniaturization of the circuit patterns of semiconductor devices is necessary. For this reason, the importance of lithography, a technique for developing a circuit pattern on a wafer surface using a photomask, is further emphasized.

[0003] For the development of a miniaturized circuit pattern, the exposure light used in an exposure process (photolithography) must have a shortened wavelength. Recently, an ArF excimer laser (wavelength 193 nm) or similar is being used as the exposure light.

[0004] On the other hand, there are binary masks, phase-shift masks and similar things as photomasks.

[0005] The binary mask has a structure in which a light-blocking pattern layer is formed on a transparent substrate. On a surface where a light-blocking pattern is formed by the binary mask, a transparent area, which does not contain a light-blocking pattern layer, allows exposure light to pass through, and a light-blocking area, which contains a light-blocking pattern layer, blocks exposure light to transfer an exposure to a resist layer on the surface of a wafer. However, the binary mask can cause problems when developing a very small pattern because the light is diffracted at the edge of the transparent area when the pattern is scaled down.

[0006] Phase-shifting masks come in three types: Levenson, outrigger, and halftone. The halftone phase-shifting mask has a structure in which a pattern of semi-transparent layers is formed on a transparent substrate. On a surface where this pattern is formed, a transparent area without a semi-transparent layer allows the passage of light, while a semi-transparent area containing a semi-transparent layer allows the passage of attenuated light. The attenuated light may have a phase difference with the light that passed through the transparent area.Accordingly, the diffraction light that occurs at the edge of the transparent part is neutralized by the exposure light that has penetrated the semi-transparent part, and thus the phase-shift mask can form a further refined tiny pattern on the surface of a wafer. [Related prior art][Patent documents] Korean patent registration no. 10-1360540, US Patent Publication No. 2004-0115537 and Japanese patent publication no. 2018-054836. SUMMARY

[0007] A mask blank according to one embodiment comprises a transparent substrate; a phase-shifting film arranged on the transparent substrate; and a light-shielding film arranged on the phase-shifting film having a TF1 value of 0.25 µm / 100 °C or less, expressed by Equation 1 below. TFT1=ΔPMT2−T1

[0008] When the thermal change of a machined mask blank, formed by machining the thickness of the transparent substrate of the mask blank to 0.6 mm and removing the light-protective film, is analyzed in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer is increased from T1 to T2, and the ΔPM is a change in position of the upper surface of the phase-shift film in the thickness direction at T2, based on a position of the upper surface of the phase-shift film at T1.

[0009] The mask blank can have a TFT1 value of 0.2 µm / 100 °C or less if T1 is 50 °C and T2 is 80 °C.

[0010] The mask blank can have a TFT1 value of 0.2 µm / 100 °C or less if T1 is 50 °C and T2 is 150 °C.

[0011] The mask blank can have a TFT2 value of 0.25 µm / 100 °C or less, which is expressed by Equation 2 below. TFT2=ΔPCT2−T1

[0012] When the thermal change of a machined mask blank, formed by machining the thickness of the mask blank to 0.6 mm, is analyzed in a thermomechanical analyzer, the measuring temperature of the thermomechanical analyzer is increased from T1 to T2, and the ΔPC is a change in position of the upper surface of the light shielding film in the thickness direction at T2, based on a position of the upper surface of the light shielding film at T1.

[0013] The mask blank can have a photon energy of 1.8 to 2.14 eV at a point with a Del_2 value of 0 according to equation 3 below, if PE1 has a value of 1.5 eV and PE2 has a value of 3.0 eV. Del_2=limΔPE→0(ΔDPSΔPE)

[0014] In Equation 3, the DPS value is a value of the phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value resulting from subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, when the light shielding film is removed from the mask blank and the surface of the phase shift film is measured with a spectroscopic ellipsometer by applying an angle of incidence of 64.5°.

[0015] The PE value is a photon energy of the incident light in a range between the PE1 value and the PE2 value.

[0016] The mask blank can have a photon energy of 3.8 to 4.64 eV at a point with a Del_2 value of 0 if PE1 has a value of 3 eV and PE2 has a value of 5 eV.

[0017] The mask blank can have a photon energy of the incident light from 3.8 eV to 4.64 eV at a point with the Del_2 value of 0, which is expressed by the equation 4 below, when PE1 has a value of 3.0 eV and PE2 has a value of 5.0 eV.

[0018] The mask blank can have a photon energy of the incident light from 1.8 eV to 2.14 eV at a point with the Del_2 value of 0, if the PE1 value is 1.5 eV and the PE2 value is 3.0 eV.

[0019] The mask blank can have an average Del_2 value of 78 to 98 ° / eV if the PE1 value is 1.5 eV and the PE2 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0.

[0020] The mask blank can have an average Del_2 value of -65 to -55 ° / eV if the PE1 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0 and the PE2 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0.

[0021] The mask blank can have an average Del_2 value of 60 to 120 ° / eV if the PE1 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0 and the PE2 value is 5.0 eV.

[0022] The mask blank can have a maximum value of Del_2, which is 105 to 300 ° / eV, if the PE1 value is 1.5 eV and the PE2 value is 5.0 eV.

[0023] The mask blank can have a photon energy of the incident light of 4.5 eV or more at a point where the Del_2 value is highest.

[0024] The phase shift film can comprise a phase difference setting layer and a protective layer arranged on the phase difference setting layer.

[0025] The phase-shift foil can contain a transition metal, silicon, oxygen, and nitrogen.

[0026] The phase difference adjustment layer can contain nitrogen in an amount of 40 to 60 atomic percent.

[0027] The protective layer can contain nitrogen in an amount of 20 to 40 atomic percent.

[0028] The protective layer can include an area where the ratio of nitrogen content to oxygen content in the thickness direction is 0.4 to 2, and the area can have a thickness of 30 to 80% compared to the total thickness of the protective layer.

[0029] The ratio between the thickness of the protective layer and the thickness of the phase-shifting film can be 0.04 to 0.09.

[0030] The thickness of the protective layer can range from 25Å to 80Å.

[0031] The phase difference adjustment layer can have a refractive index of 2 to 4 for light with a wavelength of 200 nm or less and an extinction coefficient of 0.3 to 0.7 for light with a wavelength of 200 nm or less.

[0032] The light-protective film may contain chromium, oxygen, nitrogen and carbon, with the chromium being present in an amount of 44 to 60 atomic%.

[0033] The mask blank can contain a multilayer film, the multilayer film can contain a phase-shifting film and the light-shielding film, and the optical density for a light with a wavelength of 200 nm or less of the multilayer film can be 3 or more.

[0034] A mask blank according to one embodiment can comprise a transparent substrate; a phase-shifting film arranged on the transparent substrate; and a light-protective film arranged on the phase-shifting film.

[0035] The mask blank can have a photon energy of the incident light of 4.0 eV to 5.0 eV at a point with the Del_2 value of 0, which is expressed by the equation 3 below, when the PE1 value is 3.0 eV and the PE2 value is 5.0 eV. Del_2=limΔPE→0(ΔDPSΔPE)

[0036] In Equation 3, the DPS value is a value of the phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value resulting from subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, when the light-shielding film is removed from the mask blank and the surface of the phase-shifting film is then measured with a spectroscopic ellipsometer by applying an angle of incidence of 64°.5°. where the PE value is a photon energy of the incident light in a range between the PE1 value and the PE2 value.

[0037] The mask blank can have a photon energy of 1.7 to 2.3 eV at a point with a Del_2 value of 0 if PE1 has a value of 1.5 eV and PE2 has a value of 3.0 eV.

[0038] The mask blank can have an average Del_2 value of 85 to 98 ° / eV if the PE1 value is 1.5 eV and the PE2 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0.

[0039] The mask blank can have an average Del_2 value of -65 to -55 ° / eV if the PE1 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0 and the PE2 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0.

[0040] The mask blank can have an average Del_2 value of 60 to 120 ° / eV if the PE1 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0 and the PE2 value is 5.0 eV.

[0041] The mask blank can have a maximum Del_2 value of 105 to 300 ° / eV if the PE1 value is 1.5 eV and the PE2 value is 5.0 eV.

[0042] The mask blank can have a photon energy of 4.5 eV or more at a point with the maximum value of the Del_2 value.

[0043] The mask blank can have a TFT1 value of 0.25 µm / 100 °C or less.

[0044] The mask blank can have a TFT1 value of 0.2 µm / 100 °C or less if T1 is 50 °C and T2 is 80 °C.

[0045] The mask blank can have a TFT1 value of 0.2 µm / 100 °C or less if T1 is 50 °C and T2 is 150 °C.

[0046] The mask blank can have a TFT2 value of 0.25 µm / 100 °C or less.

[0047] The phase shift film can contain a phase difference setting layer and a protective layer arranged on the phase difference setting layer.

[0048] The phase-shift foil can contain a transition metal, silicon, oxygen, and nitrogen.

[0049] The phase difference adjustment layer can contain nitrogen in an amount of 40 to 60 atomic percent.

[0050] The protective layer can contain nitrogen in an amount of 20 to 40 atomic percent.

[0051] The protective layer can include an area where the ratio of nitrogen content to oxygen content in the thickness direction is 0.4 to 2, and the area can have a thickness of 30 to 80% compared to the total thickness of the protective layer.

[0052] The ratio between the thickness of the protective layer and the thickness of the phase-shifting film can be 0.04 to 0.09.

[0053] The thickness of the protective layer can range from 25Å to 80Å.

[0054] The phase difference adjustment layer can have a refractive index of 2 to 4 for light with a wavelength of 200 nm or less and an extinction coefficient of 0.3 to 0.7 for light with a wavelength of 200 nm or less.

[0055] The light-protective film may contain chromium, oxygen, nitrogen and carbon, with the chromium being present in an amount of 44 to 60 atomic%.

[0056] The mask blank can contain a multilayer film, the multilayer film can contain a phase-shifting film and the light-shielding film, and the optical density for light with a wavelength of 200 nm or less of the multilayer film can be 3 or more.

[0057] A photomask according to another embodiment comprises a transparent substrate; a phase-shifting film arranged on the transparent substrate; and a light-shielding film arranged on the phase-shifting film.

[0058] The photomask can have a TFT3 value of 0.25 µm / 100 °C or less, which is expressed by equation 4 below. TFT3=ΔpPMT2−T1

[0059] When the thermal change of a processed photomask, formed by processing the thickness of the transparent substrate of the photomask to 0.6 mm and removing the light-shielding pattern film, is analyzed in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer is increased from T1 to T2, and the ΔpPM is a change in position of the upper surface of the phase-shift film in the thickness direction at T2, based on a position of the upper surface of the phase-shift film at T1.

[0060] A photomask according to another embodiment comprises a transparent substrate; a phase-shifting film arranged on the transparent substrate; and a light-shielding film arranged on the phase-shifting film.

[0061] The photomask has a photon energy of the incident light at a point with a Del_1 of 0, expressed by equation 5 below, when PE1 has a value of 3.0 eV and PE2 has a value of 5.0 eV. Del_1=limΔPE→0(ΔpDPSΔPE)

[0062] In equation 5, the pDPS value is a value of the phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value resulting from subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, when the light shield pattern film is removed from the photomask and the surface of the phase shift pattern film is measured with a spectroscopic ellipsometer in which an angle of incidence of 64.5° is applied.

[0063] The PE value is a photon energy of the incident light in a range between the PE1 value and the PE2 value.

[0064] A manufacturing device for a semiconductor element according to another embodiment comprises a light source and a photomask into which light from the light source enters and the incident light is selectively transferred to be projected onto a surface of a semiconductor wafer.

[0065] The photomask comprises a transparent substrate, a phase-shift pattern film arranged on the transparent substrate, and a light-shielding pattern film arranged on top of the phase-shift film.

[0066] The photomask can have a TFT3 value of 0.25 µm / 100 °C or less, which is expressed by equation 4 below. TFT3=ΔpPMT2−T1

[0067] When the thermal change of a processed photomask, formed by processing the thickness of the transparent substrate of the photomask to 0.6 mm and removing the light-shielding pattern film, is analyzed in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer is increased from T1 to T2, and the ΔpPM is a change in position of the upper surface of the phase-shift film in the thickness direction at T2, based on a position of the upper surface of the phase-shift film at T1.

[0068] A manufacturing device for a semiconductor element according to another embodiment comprises a light source and a photomask into which light from the light source enters and the incident light is selectively transferred to be projected onto a surface of a semiconductor wafer.

[0069] The photomask has a photon energy of the incident light of 4.0 to 5.0 eV at a point with a Del_1 of 0, expressed by equation 5 below, when PE&tA;1&tB; has a value of 3.0 eV and PE&tC;2&tD; has a value of 5.0 eV. Del_1=limΔPE→0(ΔpDPSΔPE)

[0070] In equation 5, the pDPS value is a value of the phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value resulting from subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, when the light shield pattern film is removed from the photomask and the surface of the phase shift pattern film is measured with a spectroscopic ellipsometer by setting an angle of incidence of 64.5°.

[0071] The PE value is a photon energy of the incident light in a range between the PE1 value and the PE2 value. List of characters Fig.Figure 1 is a conceptual view for representing a mask blank according to an embodiment of the present disclosure; Fig. Figure 2 is a conceptual view showing a mask blank according to another embodiment of the present disclosure; Fig. Figure 3 is a conceptual view showing the principle of measuring the phase difference between the P-wave and the S-wave of the reflected light from a phase-shift film using a spectroscopic ellipsometer; Fig. Figure 4 is a diagram illustrating a thermal variation value in the direction of the thickness as a function of the temperature of a phase shift film from Example 1; Fig. Figure 5 is a diagram illustrating a thermal variation value in the direction of thickness as a function of the temperature of a phase shift film from Example 2; Fig.Figure 6 is a diagram of the measurement distribution of the DPS values ​​as a function of the photon energy of examples 4; Fig. Figure 7 is a diagram of the measurement distribution of the Del_2 values ​​as a function of the photon energy of Example 4; Fig. Figure 8 is a diagram of the measurement distribution of the DPS values ​​as a function of the photon energy of example 5; Fig. Figure 9 is a diagram of the measurement distribution of the Del_2 values ​​as a function of the photon energy of Example 5; Fig. Figure 10 is a diagram of the measurement distribution of the DPS values ​​as a function of the photon energy of example 6; Fig. Figure 11 is a diagram of the measurement distribution of the Del_2 values ​​as a function of the photon energy of Example 6; Fig. Figure 12 is a diagram of the measurement distribution of the DPS values ​​as a function of the photon energy of the comparison example 3; Fig.Figure 13 is a diagram of the measurement distribution of the Del_2 values ​​as a function of the photon energy of the comparison example 3; Fig. Figure 14 is a diagram of the measurement distribution of the DPS values ​​as a function of the photon energy of the comparison example 4; and Fig. Figure 15 is a diagram of the measurement distribution of the Del_2 values ​​as a function of the photon energy of the comparison example 4. DETAILED DESCRIPTION

[0072] Exemplary embodiments of the present disclosure are described in detail below with reference to the accompanying drawings, so that they can be easily implemented by those skilled in the field to which the present invention relates. However, these exemplary embodiments can be implemented in many different forms and are not to be understood as being limited to the embodiments presented here.

[0073] In this application, the term "degree" is used to describe values ​​similar to "approximately," "essentially," and the like, when referring to values ​​that approximate the value when a tolerance appropriate to the manufacturing process and the material is specified. Additionally, these terms are used to facilitate understanding of examples and to prevent unauthorized use of content that refers to an exact or absolute number.

[0074] Throughout the application, the expression ‘combination(s) thereof’ contained in a Markush expression refers to one or more mixtures or combinations selected from the group of constituents mentioned in the Markush expression; that is, it refers to the one or more constituents selected from the group of constituents that are included.

[0075] In this application, the designation “A and / or B” means “A, B or A and B”.

[0076] In this application, terms such as "first", "second", "A" or "B" are used to distinguish between identical terms unless otherwise stated.

[0077] In this application, “B is placed on A” means that B is placed in direct contact with A or placed above A, with another layer or structure possibly in between, and should therefore not be interpreted as limiting this expression to B being placed in direct contact with A.

[0078] In this application, a singular form is interpreted contextually to include both a plural form and a singular form, unless explicitly stated otherwise.

[0079] In this application, the transparent part refers to an area on the surface of the photomask where no phase-shift film is formed and which therefore transmits exposure light, and the semi-transparent part refers to an area where the phase-shift film is formed and which therefore transmits attenuated exposure light.

[0080] In this application, the angle of incidence refers to the angle between the direction of the incident light of a spectroscopic ellipsometer and the normal of the phase-shift foil.

[0081] In this application, room temperature means 20 °C to 25 °C.

[0082] A semiconductor device can be fabricated by transferring a pattern onto the surface of a semiconductor wafer. Specifically, a photomask containing a designed pattern is placed on a semiconductor wafer with a resist layer and then exposed to a light source. In this case, the resist layer of the semiconductor wafer takes on the shape of a specific pattern through treatment with a developing solution.

[0083] As semiconductors become highly integrated, increasingly miniaturized circuit patterns are required. To create a miniaturized pattern on a semiconductor wafer, exposure light with a shorter wavelength than conventional exposure light can be used. For example, an ArF excimer laser (wavelength 193 nm) can be used as exposure light for miniaturized pattern formation.

[0084] A light source that generates exposure light with a short wavelength may require high optical power. Such a light source can increase the temperature of a photomask during an exposure process.

[0085] Thin films forming a pattern in the photomask can exhibit physical properties such as thickness and height that change with temperature. Each thin film is not made of the same material and may have a multilayered structure consisting of at least two or more layers. Furthermore, since the thin films are sometimes subjected to oxidation, heat treatment, or similar processes, differences can arise between the properties of the thin film itself immediately after sputtering and those of the thin film in the finished mask blank. In particular, if the temperature-dependent variations in thickness, height, and other properties of the individual thin films are not controlled, the resolution of a pattern formed on a semiconductor wafer can degrade.

[0086] To develop a tinier circuit pattern with excellent resolution, the phase difference and transmittance of the phase-shift foil must be controlled more precisely, and the thickness of the phase-shift foil must be further reduced.

[0087] A protective layer can be applied to the surface of the phase-shift film to improve its durability. Methods for forming a protective layer on the surface of the phase-shift film include: a method for forming a protective layer without the application of a separate process through a natural oxidation reaction; a method for forming a separate layer on the surface of the phase-shift film through sputtering, etc.; and a method for applying a heat treatment process to the surface of the phase-shift film.

[0088] When a natural oxidation process is used, the distribution of the optical properties of the phase-shift film in the plane may be uneven, and the durability of the phase-shift film may be insufficient. If a process for forming a separate layer on the surface of the phase-shift film or a heat treatment process is used, the optical properties of the entire phase-shift film can vary significantly due to the influence of the protective layer formed.

[0089] The inventors of the embodiments completed the embodiments by experimentally confirming that it is possible to provide a mask blank with improved resolution by a method such as adjusting the thermal variation value as a function of the temperature of the films contained in the mask blank within a certain range.

[0090] The embodiments are described in more detail below.

[0091] Fig. Figure 1 is a conceptual view for representing a mask blank according to an embodiment of the present application; one embodiment is described with reference to Fig. 1 described.

[0092] A mask blank according to 100 of an embodiment of the present application comprises a transparent substrate 10, a phase-shifting film 20 arranged on the transparent substrate 10; and a light-protective film 30 arranged on the phase-shifting film 20.

[0093] The material of the transparent substrate 10 is not limited, as long as it is translucent and can be applied to the photomask. In particular, the transmittance of the transparent substrate 10 with respect to exposure light with a wavelength of 200 nm or less can be 85% or more. The transmittance can be 87% or more. The transparent substrate 10 can, for example, be a synthetic quartz substrate. In this case, the attenuation of the light passing through the transparent substrate 10 can be suppressed.

[0094] Furthermore, optical distortions can be suppressed by adjusting the surface properties such as flatness and roughness of the transparent substrate 10.

[0095] The phase shift film 20 can be arranged on a top side of the transparent substrate 10. Thermal variation characteristics of phase-shift films

[0096] The mask blank can have a TFT1 value of 0.25 µm / 100 °C or less, which is expressed by Equation 1 below. TFT1=ΔPMT2−T1

[0097] When the thermal change of a machined mask blank, formed by machining the thickness of the transparent substrate of the mask blank to 0.6 mm and removing the light-protective film, is analyzed in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer is increased from T1 to T2, and the ΔPM is a change in position of the upper surface of the phase-shift film in the thickness direction at T2, based on a position of the upper surface of the phase-shift film at T1.

[0098] The optical properties of the phase-shift film 20 depend on various factors, such as the composition of the elements contained within the phase-shift film 20, as well as its density and thickness. To maximize the resolution of the mask blank 100, the phase-shift film 20 is designed and manufactured taking these factors into account. During the exposure process, the phase-shift film 20 may be exposed to heat generated by a light source. This heat can alter the thickness, tension, and other properties of the phase-shift film 20. In such cases, the optical properties of the phase-shift film may change from a previously determined value.Furthermore, if such a phase-shift foil 20 is structured, deformation of the structured phase-shift foil can easily occur, which can reduce the resolution of a photomask. The embodiments can effectively suppress a reduction in the resolution of the mask blank by means of a method for controlling the thermal change of the phase-shift foil and the like.

[0099] The TFT1 value according to Equation 1 can be controlled and adjusted by various factors, such as the type of elements comprising the phase-shift film 20, the content of the individual elements, the strength of the magnetic field applied during a sputtering process, the rotational speed of the substrate, the electrical power applied to a target, the composition of an atmospheric gas, the temperature during sputtering, and the conditions during a post-treatment process. In particular, the embodiment can control the TFT1 value of the phase-shift film 20 by employing a method such as adjusting the magnetic field strength applied during the formation of the phase-shift film 20.

[0100] When the phase-shift film 20 is formed, a magnetic field can be generated in a sputtering chamber by placing a magnet in the sputtering system, and the plasma can be distributed across the front surface of a sputtering target. Furthermore, the density of the phase-shift film 20 formed by the sputtering system can be adjusted by controlling the distribution and intensity of the magnetic field.

[0101] The higher the magnetic field strength, the higher the density of the plasma formed in the chamber, resulting in a dense phase-shift film 20. Conversely, the weaker the magnetic field strength, the lower the density of the plasma formed in the chamber, resulting in a sparse phase-shift film 20. This means that the density of the phase-shift film 20 can be adjusted by changing the magnetic field conditions of the sputtering system, thereby controlling the TFT1 value.

[0102] The TFT1 value is measured using a thermomechanical analyzer. Specifically, a tip of the thermomechanical analyzer is positioned on the surface of the phase shift film 20 to be measured. A fixed load is then applied to the surface of the phase shift film 20 through the tip, and the surface of the phase shift film 20 is heated at a temperature increase rate preset in the embodiment. This results in a change in the position of the upper surface of the phase shift film in the thickness direction, i.e., the TFT1 value.

[0103] In contrast to simply measuring the thickness of a thin film as a function of temperature, measuring the TFT1 value in the same way as described above allows for a comprehensive evaluation of the stress change of the thin film as a function of temperature change, the degree of thermal expansion of the thin film, the degree of deformation of the substrate containing the thin film, and similar factors.

[0104] The TFT1 value is measured under the condition of a peak load of 0.05 N, a temperature rise rate of 10 °C / min and a measurement temperature range of 30 to 200 °C.

[0105] In this embodiment, the thickness of the transparent substrate 10 is set to 0.6 mm when measuring the TFT value. This allows the mask blank to be easily inserted into the thermomechanical analyzer. Methods for controlling the thickness of the transparent substrate 10 include, for example, etching the opposite surface of the transparent substrate 10, which is located opposite a surface of the transparent substrate 10 on which the phase-shift film 20 is arranged, cutting a portion of the transparent substrate 10 on which the phase-shift film 20 is arranged, and the like.

[0106] When measuring the TFT1 value, the measurement is performed after removing the light-shielding film 30 located on the phase-shift film 10. If another layer is applied between the phase-shift film 20 and the light-shielding film 30, this other layer is also removed. That is, a test object mask blank 100 is processed and measured in such a way that the outermost surface of the phase-shift film 20 can be exposed. Etching can be used to remove the light-shielding film 30 and the other films. However, the present application is not limited to this method.

[0107] On the upper surface of the phase-shift film 20, there may be an area where the phase-shift film 20 and another thin film (e.g., a light-blocking layer) in contact with the phase-shift film 20 are mixed. In this case, the TFT1 value is measured after even the mixed portion has been removed.

[0108] Since it is technically difficult to remove the mixed part without damaging the phase shift film 20, the mixed part and the upper part of the phase shift film are removed so that the processed phase shift film 20 has a thickness of 50 nm or more, and thus the TFT value is measured.

[0109] For example, the Q400 model from TA INSTRUMENT is available as a thermomechanical analyzer for measuring the TFT1 value.

[0110] When calculating the TFT1 value, ΔPM represents the absolute value of the change in position of the upper surface of the phase-shift foil in the thickness direction at T2, based on the position of the upper surface of the phase-shift foil at T1. For example, if the change in thickness in the direction of the thickness of the phase-shift foil at T1 is 0.2 µm and the change in thickness in the direction of the thickness of the phase-shift foil at T2 is 0.5 µm, then ΔPM is 0.3 µm.

[0111] T1 is the initial temperature of the thermomechanical analyzer when the TFT1 value is measured.

[0112] T2 is a temperature increased from the initial temperature of the thermomechanical analyzer when the TFT1 value is measured.

[0113] The TFT1 value is calculated with a unit of µm / 100 °C. For example, if the T1 value is 30 °C, the T2 value is 200 °C, and the ΔPM value is 0.25 µm, the calculated TFT value is... 0.25200−30*100=0.147 μm / 100°C.

[0114] The TFT1 value of the mask blank 100 can be 0.25 µm / 100 °C or less. The TFT1 value can be 0.2 µm / 100 °C or less. The TFT1 value can be 0.18 µm / 100 °C or less. The TFT1 value can be 0.1 µm / 100 °C or more. The TFT1 value can be 0.12 µm / 100 °C or more. The TFT1 value can be 0.15 µm / 100 °C or more.

[0115] If T1 is 30 °C and T2 is 200 °C, the TFT1 value of the mask blank can be 0.25 µm / 100 °C or less. The TFT1 value can be 0.2 µm / 100 °C or less. The TFT1 value can be 0.18 µm / 100 °C or less. The TFT1 value can be 0.1 µm / 100 °C or more. The TFT1 value can be 0.12 µm / 100 °C or more. The TFT1 value can be 0.15 µm / 100 °C or more.

[0116] If T1 is 50 °C and T2 is 80 °C, the TFT1 value of the mask blank can be 0.25 µm / 100 °C or less. The TFT1 value can be 0.2 µm / 100 °C or less. The TFT1 value can be 0.18 µm / 100 °C or less. The TFT1 value can be 0.1 µm / 100 °C or more. The TFT1 value can be 0.12 µm / 100 °C or more. The TFT1 value can be 0.15 µm / 100 °C or more.

[0117] In such a case, it is possible to suppress the deformation of the phase-shift pattern film caused by the heat generated during the exposure process and to improve the resolution of the photomask. Furthermore, the phase-shift pattern film can exhibit stable durability.

[0118] If T1 is 50 °C and T2 is 150 °C, the TFT1 value of the mask blank can be 0.25 µm / 100 °C or less. The TFT1 value can be 0.2 µm / 100 °C or less. The TFT1 value can be 0.18 µm / 100 °C or less. The TFT1 value can be 0.1 µm / 100 °C or more. The TFT1 value can be 0.12 µm / 100 °C or more. The TFT1 value can be 0.15 µm / 100 °C or more.

[0119] In such a case, the photomask can exhibit excellent resolution even at relatively high temperatures.

[0120] If T1 is between 100 and 140 °C and T2 is expressed as T2 = T1 + 5 °C, the TFT1 value of the mask blank can be 0.1 µm or less. The TFT1 value can be 0.07 µm / 100 °C or less. The TFT1 value can be 0.05 µm / 100 °C or less. The TFT1 value can be 0.005 µm / 100 °C or more. The TFT1 value can be 0.01 µm / 100 °C or more. The TFT1 value can be 0.02 µm / 100 °C or more. In such a case, changes in the optical properties and pattern distortions caused by an increase in atmospheric temperature during the exposure process can be suppressed in the patterned phase-shift film.

[0121] If T1 is 170 to 180 °C and T2 is expressed as T2 = T1 + 5 °C, the TFT1 value of the mask blank can be 0.15 µm or less. The TFT1 value can be 0.12 µm / 100 °C or less. The TFT1 value can be 0.1 µm / 100 °C or less. The TFT1 value can be 0.005 µm / 100 °C or more. The TFT1 value can be 0.01 µm / 100 °C or more. The TFT1 value can be 0.02 µm / 100 °C or more. In such a case, the phase-shift film can exhibit stable durability in a high-temperature atmosphere. Thermal variation characteristics of the light-protective film

[0122] The mask blank 100 can achieve a TFT2 value of 0.25 µm / 100 °C, which is expressed by the equation 2 below. TFT2=ΔPCT2−T1

[0123] If the thermal change of the machined mask blank 100, which is formed by machining the thickness of the transparent substrate 10 of the mask blank to 0.6 mm, is analyzed in a thermomechanical analyzer, the measuring temperature of the thermomechanical analyzer is increased from T1 to T2, and ΔPC is a change in position of the upper surface of the light-shielding film 30 in the thickness direction at T2 based on a position of the upper surface of the light-shielding film 30 at T1.

[0124] The patterned light-shielding film 30 can be arranged on the pattern of the phase-shifting film 20 to form a blind pattern. Like the pattern of the phase-shifting film 20, the pattern of the light-shielding film 30 can also be exposed to the heat generated by a high-power light source during an exposure process. As a result, the thickness of the light-shielding film 30, its internal stress, the degree of deformation of a substrate containing the light-shielding film, and similar factors can vary. Such variations can be a factor that reduces the resolution of a pattern to be developed, as in the case of the phase-shifting film 20. By setting the TFT2 value of the mask blank within a preset range in the embodiment, the embodiment can suppress dimensional changes in the thickness of the light-shielding film 30 caused by the heat generated by the high-power light source.

[0125] The TFT2 value of the mask blank 100 can be influenced by various factors, such as the elements of the light shielding film 30, the process conditions during sputtering, and the thickness of the light shielding film 30. Specifically, the magnetic field strength was controlled during the sputtering of the light shielding film 30, thereby adjusting the TFT2 value of the mask blank 100. In particular, the TFT2 value was adjusted by controlling the density of the light shielding film 30, which was formed by controlling the magnetic field during the sputtering process.

[0126] The TFT2 value is measured using a thermomechanical analyzer. Specifically, a tip of the thermomechanical analyzer is positioned on the surface of the light-shielding film 30 to be measured. A fixed load is then applied to the surface of the light-shielding film 30 via the tip, and the surface of the light-shielding film 30 is heated at a temperature rise rate preset in the embodiment to measure a change in position in the direction of the thickness of the light-shielding film as a function of temperature.

[0127] In contrast to simply measuring the thickness of the light-protective film 30 as a function of temperature, measuring the TFT2 value in the same way as above allows for a comprehensive evaluation of the stress change of the light-protective film 30 as a function of temperature change, the degree of thermal expansion of the light-protective film 30, the degree of deformation of the substrate containing the light-protective film 30, and the like.

[0128] The same measurement conditions apply to the thermomechanical analyzer when measuring the TFT2 value as when measuring the TFT1 value.

[0129] When measuring the TFT2 value, the thickness of the transparent substrate 10 is set to 0.6 mm. The procedure for processing the transparent substrate 10 is the same as for measuring the TFT1 value.

[0130] If another layer is present on the light-protective film 30 when measuring the TFT2 value, the measurement is carried out after removing the additional layer. Etching can be used as a method for removing the other film. However, the present application is not limited to this method.

[0131] Depending on the manufacturing process, there may be a section where the light-shielding film 30 and other layers arranged on the light-shielding film 30 are mixed. In this case, the TFT2 value is measured after the mixed portion has been removed.

[0132] When the mixed part is removed, it is technically difficult to remove the mixed part without damaging the light-blocking film, so the mixed part and the top part of the light-blocking film are removed so that the light-blocking film has a thickness of 40 nm or more after processing.

[0133] As an example, a Q400 model offered by TA INSTRUMENT can be used as a thermomechanical analyzer to measure the TFT2 value.

[0134] When calculating the TFT2 value, ΔPC represents the absolute value of a change in position of the top surface of the light-blocking film 30 in the thickness direction at T2, based on the position of the top surface of the light-blocking film 30 at T1. For example, if the change in thickness in the direction of the thickness of the light-blocking film at T1 is 0.2 µm and the change in thickness in the direction of the thickness of the light-blocking film at T2 is 0.5 µm, then ΔPC corresponds to 0.3 µm.

[0135] T1 is the initial temperature of the thermomechanical analyzer when the TFT2 value is measured.

[0136] T2 is a temperature increased from the initial temperature of the thermomechanical analyzer when the TFT2 value is measured.

[0137] The TFT2 value is calculated so that it has a unit of T2-T1 values, which is µm / 100 °C. For example, if the T1 value is 30 °C, the T2 value is 200 °C, and the ΔPM value is 0.25 µm, the calculated TFT value * 100 = 0.147 µm / 100 °C.

[0138] The TFT2 value of the mask blank 100 can be 0.25 µm / 100 °C or less. The TFT2 value can be 0.2 µm / 100 °C or less. The TFT2 value can be 0.1 µm / 100 °C or less. The TFT2 value can be 0.07 µm / 100 °C or less. The TFT2 value can be 0.01 µm / 100 °C or more. The TFT2 value can be 0.03 µm / 100 °C or more. The TFT2 value can be 0.05 µm / 100 °C or more.

[0139] The mask blank 100 can have a TFT2 value of 0.25 µm / 100 °C or less when T1 is 30 °C and T2 is 200 °C. The TFT2 value can be 0.2 µm / 100 °C or less. The TFT2 value can be 0.1 µm / 100 °C or less. The TFT2 value can be 0.07 µm / 100 °C or less. The TFT2 value can be 0.01 µm / 100 °C or more. The TFT2 value can be 0.03 µm / 100 °C or more. The TFT2 value can be 0.05 µm / 100 °C or more.

[0140] The mask blank 100 can have a TFT2 value of 0.8 µm / 100 °C or less if T1 is 50 °C and T2 is 150 °C. The TFT2 value can be 0.7 µm / 100 °C or less. The TFT2 value can be 0.6 µm / 100 °C or less. The TFT2 value can be 0.2 µm / 100 °C or more. The TFT2 value can be 0.3 µm / 100 °C or more. The TFT2 value can be 0.5 µm / 100 °C or more.

[0141] The mask blank 100 can have a TFT2 value of 0.8 µm / 100 °C or less if T1 is 50 °C and T2 is 100 °C. The TFT2 value can be 0.7 µm / 100 °C or less. The TFT2 value can be 0.6 µm / 100 °C or less. The TFT2 value can be 0.2 µm / 100 °C or more. The TFT2 value can be 0.3 µm / 100 °C or more. The TFT2 value can be 0.5 µm / 100 °C or more.

[0142] In this case, during exposure, it can be prevented that the optical properties of the light-protective film 30 change and that the resolution of the photomask is degraded by the heat emanating from a high-performance light source.

[0143] If T1 is between 100 °C and 140 °C and T2 is expressed as T2 = T1 + 5 °C, the TFT2 value in the mask blank can be 0.1 µm / 100 °C or less. The TFT2 value can be 0.07 µm / 100 °C or less. The TFT2 value can be 0.05 µm / 100 °C or less. The TFT2 value can be 0.005 µm / 100 °C or more. The TFT2 value can be 0.01 µm / 100 °C or more. The TFT2 value can be 0.02 µm / 100 °C or more. In such a case, when the patterned light-shielding film is used in a lithography process, mold deformation due to a temperature increase can be suppressed.

[0144] The mask blank 100 can have a TFT2 value of 0.15 µm / 100 °C or less if T1 is 170 °C to 180 °C and T2 is expressed as T2 = T1 + 5 °C. The TFT2 value can be 0.12 µm / 100 °C or less. The TFT2 value can be 0.1 µm / 100 °C or less. The TFT2 value can be 0.005 µm / 100 °C or more. The TFT2 value can be 0.01 µm / 100 °C or more. The TFT2 value can be 0.02 µm / 100 °C or more. In such a case, the patterned light-protective film can exhibit stable optical properties and a long service life at high temperatures. Layer structure of the phase shift film

[0145] Fig. Figure 2 is a conceptual view showing a mask blank according to another embodiment of the present application. One embodiment is described with reference to Fig. 2 described.

[0146] The phase shift film 20 can comprise a phase difference setting layer 21 and a protective layer 22 arranged on the phase difference setting layer 21.

[0147] The phase shift foil 20, the phase difference setting layer 21 and the protective layer 22 can contain a transition metal, silicon, oxygen and nitrogen.

[0148] The phase-difference adjustment layer 21 is a layer in which the transition metal, silicon, oxygen, and nitrogen are uniformly present in the phase-shift film 20 at a concentration of approximately 5 atomic percent. The phase-difference adjustment layer 21 can significantly influence the phase difference and the transmittance of the light passing through the phase-shift film 20.

[0149] Specifically, the phase-difference adjustment layer 21 has the property of shifting the phase of the exposure light incident from the back of the transparent substrate 10. Due to this property, the phase-shift film 20 effectively cancels the diffracted light generated at the edge of a transparent area in a photomask, thus further improving the resolution of the photomask during a lithography process.

[0150] Furthermore, the phase-difference adjustment layer 21 attenuates the incident light from the back of the transparent substrate 10. This allows the phase-shift film 20 to block the transmission of the light and simultaneously cancel out the diffracted light generated at the edge of the transparent area.

[0151] The protective layer 22 is a layer formed on the surface of the phase-shift film and exhibits a distribution in which the oxygen content decreases continuously while the nitrogen content simultaneously increases continuously with increasing thickness from the surface. The protective layer 22 can improve the durability of the phase-shift film 20 by preventing damage to the phase-shift film 20 or the structured phase-shift film during an etching or cleaning process of the photomask. Furthermore, the protective layer 22 can suppress oxidation of the phase-difference adjustment layer 21 by the exposure light during the exposure process. Optical properties of a phase-shift film, measured with an ellipsometer

[0152] The mask blank can have a photon energy of 1.8 to 2.14 eV at a point with a Del_2 value of 0 according to equation 4 below, if PE1 has a value of 1.5 eV and PE2 has a value of 3.0 eV. Del_2=limΔPE→0(ΔDPSΔPE)

[0153] In equation 4, the DPS value is a phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value resulting from subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, when the light shielding film is removed from the mask blank and the surface of the phase shift film is measured with a spectroscopic ellipsometer by applying an angle of incidence of 64.5°.

[0154] The PE value is a photon energy of the incident light in a range between the PE 1 value and the PE 2 value.

[0155] The resolution of the photomask can be improved by precisely adjusting the optical properties of the phase-shift film 20.

[0156] Specifically, the phase difference and transmittance of the phase-shift film 20 with respect to the exposure light can be adjusted simultaneously. The phase difference and transmittance of the phase-shift film 20 can be controlled by adjusting its components, thickness, and other properties. The thickness, transmittance, and phase shift of the phase-shift film 20 are interrelated properties. However, the phase difference and transmittance are in a tension relationship, making it difficult to achieve the desired values ​​simultaneously.

[0157] The embodiment can provide a further thinned phase-shift film 20, the phase difference and transmittance of which for light with a wavelength of 200 nm or less can be controlled within the ranges specified in the embodiment by controlling the phase difference distribution of the P- and S-waves of the phase-shift film measured with an ellipsometer.

[0158] Fig. Figure 3 is a conceptual view illustrating the principle of measuring the phase difference between the P-wave and the S-wave of the reflected light from a phase-shift film using a spectroscopic ellipsometer. One embodiment is described with reference to Fig. 3 described.

[0159] The value of the phase difference (Δ) between the P-wave (P') and the S-wave (S') of the reflected light (L) r ) can depend on the photon energy of the incident light (L i) of a spectroscopic ellipsometer at a fixed angle of incidence (0). The Del_2 value can be varied by measuring the phase difference (Δ) between the P-wave (P') and the S-wave (S') of the reflected light (L). r ) in relation to the photon energy of the incident light (L i ) of the phase shift foil 20 can be calculated.

[0160] The distribution of the Del_2 value can be adjusted by controlling various factors, such as the elements comprising the phase-shift film 20, the conditions of a sputtering process, the thickness of the phase-shift film 20, and an angle of incidence set in a spectroscopic ellipsometer. In particular, the distribution of the Del_2 value of the phase-shift film 20 can be controlled by a method in which, for example, the strength of a magnetic field applied during the formation of the phase-shift film 20 is adjusted.

[0161] The Del_2 value is measured with a spectroscopic ellipsometer. It is the phase difference (Δ) between the P-wave (P') and the S-wave (S') of the reflected light (L). r The phase shift of the film can be measured, for example, with the MG-PRO model available from NANO-VIEW.

[0162] When the distribution of the Del_2 value of the phase-shift foil 20 is measured, the measurement is performed after the light-shielding foil 30 applied to the phase-shift foil 10 has been removed. If another thin foil is applied between the phase-shift foil 20 and the light-shielding foil 30, this other foil is also removed. An etching process or similar method can be used to remove the light-shielding foil 30 and the other foils. However, the present application is not limited to this. Since it is technically difficult to remove the other foil on the phase-shift foil 20 without damaging the phase-shift foil, damage to the phase-shift foil of 1 nm or less in the direction of its thickness during the etching process is permissible.

[0163] The mask blank can have a photon energy of 1.8 to 2.14 eV at a point with a Del_2 value of 0 if PE1 has a value of 1.5 eV and PE2 has a value of 3.0 eV. The photon energy can range from 1.85 eV to 2.1 eV. The photon energy can range from 1.9 eV to 2.05 eV. In such a case, the phase-shift film 20 can exhibit a desired transmittance and phase difference with respect to short-wavelength exposure light and have a reduced thickness.

[0164] The mask blank can have a photon energy of 3.8 to 4.64 eV at a point with a Del_2 value of 0 if PE1 has a value of 3 eV and PE2 has a value of 5 eV.

[0165] When the incident light (L i ) with the high photon energy of the incident light is directed onto the object being measured, the incident light (L) i ) due to the short wavelength of the incident light (L i) reflected at a shallow depth from or within the surface of the phase-shift foil 20. When analyzing the phase difference of the P-wave and S-wave of reflected light generated by irradiating the surface of the phase-shift foil 20 with incident light (L i ), whose photon energy is set to a high level, the optical properties of the surface section of the phase-shifting film 20, in particular the optical properties of the protective layer 22, can be determined.

[0166] The protective layer 22 is applied to the phase-difference adjustment layer 21 to protect the phase-difference adjustment layer 21 from light exposure and cleaning solutions. If the thickness of the protective layer 22 increases and the protective layer 22 has a denser structure, it can provide more stable protection for the phase-difference adjustment layer 21. However, if the protective layer 22 is formed solely with the aim of providing stable protection for the phase-difference adjustment layer 21, the optical properties of the entire phase-shift film 20 can be significantly altered by the formation of the protective layer 22. In such a case, the phase-shift film 20 may exhibit properties that deviate from the originally intended optical characteristics.The embodiment can provide a phase-shift film 20 in which the phase difference setting layer 21 is stably protected, while the optical properties are not substantially changed compared to before the formation of the protective layer 22 by controlling the distribution properties of the P-wave and the S-wave of the reflected light of the phase-shift film 20.

[0167] The photon energy distribution at a point with a Del_2 value of 0, when the PE1 value is 3 eV and the PE2 value is 5 eV, can be adjusted by controlling factors such as the composition of the atmospheric gas, the annealing temperature, and the temperature increase rate during an annealing process of the phase-difference setting layer 21. In particular, the Del_2 value can be controlled by adjusting the temperature and time of the heat treatment when the annealing process is performed on the surface of the formed phase-difference setting layer 21 after UV light treatment.

[0168] The mask blank 100 can exhibit a photon energy of 3.8 to 4.64 eV at a point with a Del_2 value of 0, if PE1 has a value of 3 eV and PE2 has a value of 5 eV. The photon energy can range from 4 eV to 4.62 eV. The photon energy can range from 4.2 eV to 4.6 eV. The photon energy can range from 4.3 eV to 4.5 eV. While the protective layer 22 adequately protects the phase-difference adjustment layer 21, in such a case the change in the optical properties of the phase-shift film 20 due to the formation of the protective layer 22 can be controlled within a predetermined range.

[0169] The mask blank 100 can have an average Del_2 value of 78° / eV to 98° / eV if the PE1 value is 1.5 eV and the PE2 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0.

[0170] If the photon energy of the incident light has a value greater than or equal to 1.5 eV and less than or equal to the range of the minimum value of the photon energy of the incident light at a point with a Del_2 value of 0, the incident light has a relatively long wavelength. Since such incident light is reflected after relatively deep penetration into the phase-shift film, the average value of Del_2, measured by adjusting the photon energy in the same range as above, reveals optical properties of the phase-difference setting layer 21, which is located in the lower part of the phase-shift film 20, and the like.

[0171] The mask blank 100 can have an average Del_2 value of 78° / eV to 98° / eV when the PE1 value is 1.5 eV and the PE2 value is the minimum value within the photon energy values ​​of the incident light at a point with a Del_2 value of 0. The average value can be 80 to 95° / eV. The average value can be 82 to 93° / eV. In this case, layer 21 can help adjust the phase difference so that the phase-shifting film 20, at a relatively small thickness, has the desired phase difference and transmittance for short-wavelength light.

[0172] The mask blank 100 can have an average Del_2 value of -65 to -55 ° / eV if the PE1 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0 and the PE2 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0.

[0173] If the photon energy value of the incident light is greater than the minimum value within the photon energy values ​​of the incident light at the point where the De1_1 value is 0, and the PE2 value has a value within a range of less than or equal to the maximum value of the photon energy values ​​of the incident light at a point with the Del_2 value of 0, an average value of the Del_2 values ​​measured by applying the above conditions is influenced by the optical properties and the like of a section located near the interface between the phase difference setting layer 21 and the protective layer 22.

[0174] The mask blank 100 can have an average Del_2 value of -65 to -55 ° / eV if the PE1 value is the minimum value within the photon energy values ​​of the incident light at a point with a Del_2 value of 0, and the PE2 value is the maximum value within the photon energy values ​​of the incident light at a point with a Del_2 value of 0. The average value can be -62 to -56 ° / eV. The average value can be -59 to -57 ° / eV. In this case, the interface formed between the phase-difference adjustment layer 21 and the protective film 22 can be prevented from significantly affecting the optical properties of the entire phase-shift film.

[0175] The mask blank 100 can have an average Del_2 value of 60 to 120 ° / eV if the PE1 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0 and the PE2 value is 5.0 eV.

[0176] The average value of Del_2, which is measured by setting the value PE1 to the maximum value within the photon energy values ​​of the incident light at the point where the value of Del_2 is 0, and the value PE2 to 5.0 eV, is influenced by the optical properties and the like of the protective layer 22.

[0177] The mask blank 100 can have an average Del_2 value of 60 to 120 ° / eV if the PE1 value is the maximum value within the photon energy values ​​of the incident light at a point with a Del_2 value of 0 and the PE2 value is 5.0 eV. The average value can be 70 to 110 ° / eV. The average value can be 80 to 105 ° / eV. In such a case, the phase-shift film 20 can exhibit stable durability while simultaneously reducing the influence of the protective layer 22 on the optical properties of the entire phase-shift film 20.

[0178] If the value of PE1 is 1.5 eV and the value of PE2 is 3.0 eV, the mask blank 100 can have an absolute difference value of 0.001 to 0.2 eV between a photon energy value of incident light at a point with the Del_2 value of 0, measured after the formation of the protective layer 22, and a photon energy value of incident light at a point with the Del_2 value of 0, measured before the formation of the protective layer 22.

[0179] During the formation of the protective layer 22 on the phase-difference adjustment layer 21, the optical properties of the phase-difference adjustment layer 21 itself can change. If the phase-difference adjustment layer 21 is annealed under controlled atmospheric pressure and temperature conditions, changes in the residual stress within the phase-difference adjustment layer 21 and in the composition of its surface can occur. Such changes can lead to fluctuations in the optical properties of the phase-difference adjustment layer 21 itself. This can result in the phase-shift film exhibiting properties that deviate from the optical properties desired in the embodiment.The embodiment can provide a mask blank that can have a higher resolution by controlling the difference in the optical properties of the phase difference adjustment layer itself before and after the formation of the protective layer.

[0180] If the value of PE1 is 1.5 eV and the value of PE2 is 3.0 eV, the mask blank 100 can exhibit an absolute difference value of 0.001 to 0.2 eV between the photon energy value of incident light at a point with a Del_2 value of 0, measured after the formation of the protective layer 22, and the photon energy value of incident light at a point with a Del_2 value of 0, measured before the formation of the protective layer 22. The absolute value can be 0.005 to 0.1 eV. The absolute value can be 0.01 to 0.008 eV. In such a case, a mask blank 100 can suppress optical changes in the phase difference adjustment layer 21 caused by the formation of the protective layer 22.

[0181] If the value of PE1 is 3.0 eV and the value of PE2 is 5.0 eV, the mask blank 100 can exhibit an absolute difference of 0.05 to 0.3 eV between the photon energy of incident light at a point with a Del_2 value of 0, measured after the formation of the protective layer 22, and the photon energy of incident light at a point with a Del_2 value of 0, measured before the formation of the protective layer 22. The absolute value can be 0.06 to 0.25 eV. The absolute value can be 0.1 to 0.23 eV. In such a case, the mask blank 100 can reduce the influence of the optical properties of the protective layer 22 itself on the optical properties of the entire phase-shift film 20.

[0182] The mask blank can have a maximum value of Del_2, which is 105 to 300 ° / eV, if the PE1 value is 1.5 eV and the PE2 value is 5.0 eV.

[0183] In this embodiment, the phase-shift film 20 can have a stable durability by setting the maximum value of Del_2 when the value of PE1 is 1.5 eV and the value of PE2 is 5.0 eV, while the change in the optical properties of the entire phase-shift film 20 caused by the formation of the protective layer 22 can be controlled within a predetermined range.

[0184] The mask blank can have a maximum Del_2 value of 105 to 300 eV when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV. The maximum value can be 120 to 200 eV. The maximum value can be 140 to 160 eV. In such a case, the phase-shift film 20 can exhibit excellent light resistance, chemical resistance, and the like, while the variations in the optical properties of the entire phase-shift film 20 are reduced due to the formation of the protective layer 22.

[0185] The mask blank can have a photon energy of 4.5 eV or more at a point that has the maximum value of Del_2 if PE1 has a value of 1.5 eV and PE2 has a value of 5.0 eV.

[0186] If the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of Del_2 is influenced by the optical properties of the protective layer 22 and the like. The embodiment controls a photon energy value at a point with the maximum value of Del_2, thereby reducing the influence of the formation of the protective layer 22 on the optical properties of the entire phase-shift film 20, while ensuring the protective layer 22 has a stable lifespan.

[0187] The mask blank can have a photon energy of 4.5 eV or more at a point with the maximum value of Del_2 if PE1 has a value of 1.5 eV and PE2 has a value of 5.0 eV. The photon energy value at a point with the maximum value of Del_2 can be 4.55 eV or more. The photon energy value at a point with the maximum value of Del_2 can be 5 eV or less. The photon energy value at a point with the maximum value of Del_2 can be 4.8 eV or less. In such a case, the phase-shift film 20 can exhibit the desired optical properties with respect to short-wavelength light while simultaneously suppressing variations in the optical properties due to exposure and cleaning processes.

[0188] The mask blank 100 can have a value of 60 to 260 eV, which is obtained by subtracting the minimum value of Del_2 from the maximum value of Del_2, if PE1 has a value of 1.5 eV and PE2 has a value of 5.0 eV.

[0189] The inventors of the present disclosure have experimentally determined that when the value of PE1 is 1.5 eV and the value of PE2 is 5.0 eV, the maximum value of Del_2 is influenced by the optical properties of the protective layer 22 of the phase shift film 20 and the minimum value of Del_2 is influenced by the optical properties of the upper part of the phase difference adjustment layer 21.

[0190] If the value of PE1 is 1.5 eV and the value of PE2 is 5.0 eV, the maximum and minimum values ​​of Del_2 can fluctuate before and after the formation of the protective layer. If the value obtained by subtracting the minimum value of Del_1 from the maximum value of Del_1 is controlled within a predetermined range, the variation in the optical properties of the entire phase-shift film 20 before and after the formation of the protective layer 22 can occur within a permissible range.

[0191] The mask blank 100 can have a value of 60 to 260 eV, which is obtained by subtracting the minimum value of Del_2 from the maximum value of Del_2 when PE1 has a value of 1.5 eV and PE2 has a value of 5.0 eV. The value resulting from subtracting the minimum value of Del_2 from the maximum value of Del_2 can be 80 to 240 eV.

[0192] The value obtained by subtracting the minimum value of Del_2 from the maximum value of Del_2 can range from 90 to 230 eV. In this case, the change in the optical properties of the entire phase-shift film before and after the formation of the protective layer can be controlled within a predefined range. Composition of the phase shift foil

[0193] Phase-shift foil 20 can include a transition metal, silicon, oxygen, and nitrogen. The transition metal can be one or more elements selected from, but not limited to, molybdenum (Mo), tantalum (Ta), zirconium (Zr), and the like. For example, the transition metal could be molybdenum.

[0194] Phase-shift foil 20 can contain 1 to 10 atomic percent of a transition metal. Phase-shift foil 20 can contain a transition metal at 2 to 7 atomic percent. Phase-shift foil 20 can contain silicon at 15 to 60 atomic percent. Phase-shift foil 20 can contain silicon at 25 to 50 atomic percent. Phase-shift foil 20 can contain nitrogen at 30 to 60 atomic percent. Phase-shift foil 20 can contain nitrogen at 35 to 55 atomic percent. Phase-shift foil 20 can contain oxygen at 5 to 35 atomic percent. Phase-shift foil 20 can contain oxygen at 10 to 25 atomic percent. In such a case, the phase-shifting film can have 20 optical properties suitable for a lithography process with short wavelength exposure light, in particular with light of a wavelength of 200 nm or less.

[0195] The phase shift foil 20 can contain additional elements besides those mentioned above. For example, the phase shift foil 20 can contain argon (Ar), helium (He), or similar materials.

[0196] The phase shift foil 20 can have a different content for each element in the thickness direction.

[0197] The content distribution for each element formed in the depth direction of the phase difference adjustment layer 21 and the protective layer 22 can be determined by measuring a depth profile of the phase shift foil 20. The depth profile of the phase shift foil 20 can be measured, for example, with a K-alpha model available from THERMO SCIENTIFIC.

[0198] The phase difference setting layer (21) and the protective layer (22) can have different contents of the individual elements, e.g. transition metals, silicon, oxygen and nitrogen.

[0199] The phase difference adjustment layer 21 can contain a transition metal at 3 to 10 atomic percent. The phase difference adjustment layer 21 can contain a transition metal at 4 to 8 atomic percent. The phase difference adjustment layer 21 can contain silicon at 20 to 50 atomic percent. The phase difference adjustment layer 21 can contain silicon at 30 to 40 atomic percent. The phase difference adjustment layer 21 can contain oxygen at 2 to 10 atomic percent. The phase difference adjustment layer 21 can contain oxygen at 3 to 8 atomic percent. The phase difference adjustment layer 21 can contain nitrogen at 40 to 60 atomic percent. The phase difference adjustment layer 21 can contain nitrogen at 45 to 55 atomic percent.If, in this case, light with a short wavelength, especially light with a wavelength of 200 nm or less, is used as the exposure light, the mask blank can exhibit excellent pattern resolution.

[0200] Since the protective layer 22 contains more oxygen, it is possible to stably protect the phase-difference adjustment layer 21 from light exposure, cleaning solution, etc. However, such a protective layer 22 can have a greater impact on the changes in the optical properties of the entire phase-shift film 20 that occur before and after the formation of the protective layer 22. Accordingly, by controlling the distribution of the oxygen and nitrogen content in the protective layer 22, the phase-shift film 20 can exhibit sufficient light and chemical resistance while simultaneously possessing the desired optical properties.

[0201] The protective layer 22 can contain nitrogen in an amount of 20 to 40 atomic percent. The protective layer 22 can contain nitrogen in an amount of 25 to 35 atomic percent. The protective layer 22 can contain oxygen in an amount of 10 to 50 atomic percent. The protective layer 22 can contain oxygen in an amount of 20 to 40 atomic percent. The protective layer 22 can contain silicon in an amount of 10 to 50 atomic percent. The protective layer 22 can contain silicon in an amount of 20 to 40 atomic percent. The protective layer 22 can contain a transition metal in an amount of 0.5 to 5 atomic percent. The protective layer 22 can contain a transition metal in an amount of 1 to 3 atomic percent. In such a case, the protective layer 22 can sufficiently suppress the deterioration of the phase-difference adjustment layer 21.

[0202] The protective layer 22 can include a region where the nitrogen content (atomic %) to oxygen content (atomic %) in the thickness direction is 1 or more. This region can have a thickness of 40 to 60% compared to the total thickness of the protective layer 22. This region can have a thickness of 45 to 55% compared to the total thickness of the protective layer 22. In this case, it is possible to effectively suppress variations in the optical properties of the phase-shifting film 20 by forming the protective layer 22.

[0203] The protective layer 22 can include a region where the ratio of nitrogen content (atomic %) to oxygen content (atomic %) in the thickness direction is 0.4 to 2, and this region can have a thickness of 30 to 80% compared to the total thickness of the protective layer 22. This region can have a thickness of 40 to 60% compared to the total thickness of the protective layer 22. In this case, it is possible to provide a mask blank with which a photomask with excellent resolution and sufficient long-term stability can be produced.

[0204] The thickness measurement of the area where the ratio of nitrogen content (atomic %) to oxygen content (atomic %) is set in the thickness direction can be confirmed by measuring the depth profile of the protective layer 22. However, it is assumed that the etch rate is constant for each depth of the protective layer 22 in the depth profile when the thickness of the area is measured. Optical properties and thickness of the individual layers of the phase shift film

[0205] The phase-shift foil 20 can exhibit a phase difference of 160 to 200° with respect to light with a wavelength of 200 nm or less. The phase-shift foil 20 can exhibit a phase difference of 160 to 200° with respect to ArF light. The phase-shift foil 20 can exhibit a phase difference of 170 to 190° with respect to light with a wavelength of 200 nm or less. The phase-shift foil 20 can exhibit a phase difference of 170 to 190° with respect to ArF light. The phase-shift foil 20 can exhibit a transmittance of 3 to 10% for light with a wavelength of 200 nm or less. The phase-shift foil 20 can exhibit a transmittance of 3 to 10% for ArF light. The phase-shift foil 20 can exhibit a transmittance of 4 to 8% for light with a wavelength of 200 nm or less. The phase-shift film 20 can have a transmittance of 4 to 8% for ArF light.In such a case, a photomask with the phase-shifting film 20 can form a more precise tiny pattern on the wafer during an exposure process using short wavelength exposure light.

[0206] The protective layer 22 can have a refractive index of 1.3 to 2 for light with a wavelength of 200 nm or less. The protective layer 22 can have a refractive index of 1.3 to 2 for ArF light. The protective layer 22 can have a refractive index of 1.4 to 1.8 for light with a wavelength of 200 nm or less. The protective layer 22 can have a refractive index of 1.3 to 1.8 for ArF light. An extinction coefficient of the protective layer 22 for light with a wavelength of 200 nm or less can be 0.2 to 0.4. An extinction coefficient of the protective layer 22 for ArF light can be 0.2 to 0.4. The extinction coefficient of the protective layer 22 for light with a wavelength of 200 nm or less can be 0.25 to 0.35. The extinction coefficient of the protective layer 22 for ArF light can be 0.25 to 0.35.In such a case, the change in the optical properties of the phase-shifting film 20 due to the formation of the protective layer 22 can be minimized.

[0207] The phase-difference setting layer 21 can have a refractive index of 2 to 4 for light with a wavelength of 200 nm or less. The phase-difference setting layer 21 can have a refractive index of 2 to 4 for ArF light. The refractive index of layer 21 for setting the phase difference with respect to light with a wavelength of 200 nm or less can be 2.5 to 3.5. The refractive index of layer 21 for setting the phase difference with respect to ArF light can be 2.5 to 3.5. The extinction coefficient for light with a wavelength of 200 nm or less of the phase-difference setting layer 21 can be 0.3 to 0.7. The extinction coefficient for ArF light of the phase-difference setting layer 21 can be 0.3 to 0.7. The extinction coefficient for light with a wavelength of 200 nm or less of the phase difference setting layer 21 can be 0.4 to 0.6.The extinction coefficient for ArF light of the phase-difference adjustment layer 21 can be between 0.4 and 0.6. In such a case, the resolution of the photomask can be further improved with the phase-shift film 20.

[0208] The optical properties of the phase-shift film 20, the protective layer 22, and the phase-difference adjustment layer 21 can be measured using a spectroscopic ellipsometer. For example, the MG-PRO instrument from NANO-VIEW can be used to measure these optical properties.

[0209] The ratio between the thickness of the protective layer 22 and the total thickness of the phase-shift film 20 can be 0.04 to 0.09. The thickness ratio can be 0.05 to 0.08. In such a case, the protective layer 22 can stably protect the phase-difference adjustment layer 21.

[0210] The thickness of the protective layer 22 can be from 25 Å to 80 Å. The thickness of the protective layer 22 can be from 35 Å to 45 Å. In such a case, it is possible to provide a phase-shifting film 20 that effectively reduces the degree of change in the optical properties of the entire phase-shifting film due to the formation of the protective layer 22 and exhibits stable optical properties even during a long exposure and cleaning process.

[0211] The phase shift film 20 and the thickness of the individual layers of which the phase shift film 20 consists can be measured by a TEM image (transmission electron microscopy) of a cross-section of the phase shift film 20. Layer structure, composition and optical properties of the light-protective film

[0212] The light-shielding film 30 can be placed on the phase-shifting film 20. The light-shielding film 30 can be used as an etching mask for the phase-shifting film 20 when the phase-shifting film 20 is etched according to a previously designed pattern. Furthermore, the light-shielding film 30 can block the transmission of the incident light from the back of the transparent substrate 10.

[0213] The light-shielding film 30 can have a single-layer structure. The light-shielding film 30 can also have a multi-layered structure consisting of two or more layers. In a sputtering process, a multi-layered light-shielding film 30 can be formed by using different atmospheric gas compositions and flow rates for each layer. In the sputtering process, a multi-layered light-shielding film 30 can be formed by using different sputtering targets for each layer.

[0214] The light-protective film 30 can contain chromium, oxygen, nitrogen, and carbon. The proportion of each element in the light-protective film 30 can vary depending on the film's thickness. In the case of a multi-layered light-protective film, the individual layers can have different compositions.

[0215] The light-protective film 30 can contain chromium in an amount of 30 to 70 atomic percent. The light-protective film 30 can contain chromium in an amount of 47 to 57 atomic percent. The light-protective film 30 can contain carbon in an amount of 5 to 30 atomic percent. The light-protective film 30 can contain carbon in an amount of 7 to 25 atomic percent. The light-protective film 30 can contain nitrogen in an amount of 3 to 30 atomic percent. The light-protective film 30 can contain nitrogen in an amount of 5 to 25 atomic percent. The light-protective film 30 can contain oxygen in an amount of 20 to 55 atomic percent. The light-protective film 30 can contain oxygen in an amount of 25 to 40 atomic percent. In this case, the light-protective film 30 can exhibit sufficient extinction properties.

[0216] The multilayer film (not shown) consists of a phase-shifting film 20 and a light-blocking film 30. The multilayer film can form a blind pattern on the transparent substrate 10 to suppress the transmission of the exposure light.

[0217] The optical density of the multilayer film for light with a wavelength of 200 nm or less can be 3 or more. The optical density of the multilayer film for ArF light can be 3 or more. The optical density of the multilayer film for light with a wavelength of 200 nm or less can be 3.5 or more. The optical density of the multilayer film for ArF light can be 3.5 or more. In such a case, the multilayer film can exhibit excellent light-blocking properties. Manufacturing process for phase shift films

[0218] The phase difference adjustment layer 21 can be produced in certain embodiments by sputtering on the transparent substrate 10.

[0219] The sputtering process can be operated with direct current or high frequency.

[0220] A target and a sputtering gas can be selected taking into account the composition of the material from which the phase difference adjustment layer 21 consists.

[0221] In a sputtering target, a target containing a transition metal and silicon, or a target containing a transition metal and a target containing silicon, can be deposited simultaneously. When a target is used as a sputtering target, the transition metal content can be 30% or less relative to the sum of the transition metal and silicon contents of the target. The proportion can be 20% or less. The proportion can be 10% or less. The proportion can be 2% or more. By using such a target, it is possible to impart the desired optical properties to a sputtered phase-shift film.

[0222] For the sputtering gas, CH4 can be used as a carbon-containing gas, O2 as an oxygen-containing gas, N2 as a nitrogen-containing gas, etc. However, the present application is not limited to this. An inert gas can be added to the sputtering gas. Ar, He, and similar gases are suitable as inert gases. However, the present application is not limited to this. The film properties of the phase difference compensation layer 21 to be formed can be adjusted depending on the type and concentration of the inert gas. By controlling the composition of the inert gas, the optical properties of the phase-shift film can be adapted. Each gas contained in the sputtering gas can be individually introduced into a chamber via different inlets. The sputtering gas can be introduced into the chamber by mixing appropriate gases.

[0223] A magnet can be positioned in the chamber to improve the uniformity of thickness and optical properties of the phase-shift foil being formed in the plane direction. By positioning the magnet on the back side of a sputtering target and rotating it at a preset speed, the plasma can be distributed more evenly across the front side of the target. The magnet can be rotated at speeds of 50 to 200 rpm.

[0224] The magnet's rotational speed can be set to a constant speed during sputtering. The magnet's rotational speed can be varied during sputtering. The magnet's rotational speed can be increased from the initial speed with uniform acceleration during sputtering.

[0225] The magnet's rotational speed can be increased from the initial speed by 5 to 20 rpm during sputtering. Alternatively, the magnet's rotational speed can be increased from the initial speed by 7 to 15 rpm. In such cases, the density distribution of the phase-shift foil in the plane can be more easily controlled.

[0226] By controlling the magnet's magnetic field, the density of the plasma generated in the sputtering chamber can be adjusted. This allows control of the density of the phase-shift film to be formed, as well as the TFT1 value of a mask blank and the optical properties of the phase-shift film. The magnetic field applied during phase-shift film formation can range from 25 to 60 mT. The magnetic field can also range from 30 to 50 mT. In such cases, thermal variation in the thickness direction of the phase-shift film can be suppressed in a lithography process using short-wavelength exposure light, resulting in a more thin phase-shift film.

[0227] In sputtering, the T / S distance (the distance between the target and the substrate) and the angle between the substrate and the target can be adjusted. The T / S distance can be 240 to 260 mm. The angle between the substrate surface and the front of the target can be 20 to 30 degrees. In such cases, the formation rate of the phase-shift film is stably controlled, and it is possible to suppress an excessive increase in the internal stress of the phase-shift film.

[0228] In the sputtering process, the rotational speed of the substrate relative to the film-forming target surface can be adjusted. The substrate rotational speed can range from 2 to 20 rpm. The fabrication speed can range from 5 to 15 rpm.

[0229] If the rotational speed of the substrate with the target surface for film formation is set within such a range, the phase-shift film can exhibit stable durability while further improving the uniformity of the optical properties in the direction of the plane.

[0230] A discharge region, comprising a plasma atmosphere within the chamber, can be created by supplying electrical energy to a target located in the sputtering chamber. By controlling the magnetic field strength and the rotational speed of the magnet, and simultaneously controlling the intensity of the electric current, the layer properties of the layer formed during sputtering can be adjusted. The intensity of the electrical power applied to the sputtering target can range from 1 to 3 kW. The electrical power intensity can range from 1.5 to 2.5 kW. The electrical power intensity can range from 1.8 to 2.2 kW. In such cases, the thermal change in the thickness direction can be controlled within a predetermined range as a function of the temperature of the phase-shifting film.

[0231] A spectroscopic ellipsometer can be integrated into the sputtering system. This allows for precise control of the film formation time while simultaneously monitoring the optical properties of the phase-difference adjustment layer being formed. By adjusting the angle formed by the direction of the incident light with the surface of the phase-difference adjustment layer, the del_2 value and other parameters of the formed phase-difference adjustment layer can be monitored in real time during the deposition process. By performing a sputtering process until the del_2 value falls within a predefined range, the desired optical properties of the phase-shifting layer can be achieved.

[0232] After completion of the sputtering process, the surface of the phase-difference adjustment layer can be irradiated with UV light. During the sputtering process, silicon in the SiO₂ matrix, which forms the transparent substrate 10, can be replaced by a transition metal, and oxygen can be replaced by nitrogen. If the sputtering process continues, the concentration of the transition metal can exceed the solubility limit, and the transition can be located at an interstitial site instead of being replaced by silicon in the SiO₂ matrix. In this case, the transition metal can form a mixture with elements such as silicon, oxygen, and nitrogen on the surface of the phase-difference adjustment layer being formed. The mixture can be in a homogeneous or inhomogeneous state.If a non-uniform mixture forms on the surface of the phase-difference setting layer, a haze defect can develop on the surface of the phase-difference setting layer due to exposure to short-wavelength light during the exposure process. Even after cleaning the phase-shift film with sulfuric acid to remove the haze, sulfur ions may remain on the surface of the phase-difference setting layer. These sulfur ions can continuously receive high energy from exposure light during a wafer exposure process, and this high-energy sulfur ion can react with the non-uniform mixture to create growth defects on the surface of the phase-difference setting layer.The embodiment can further improve the light and chemical resistance of the phase difference adjusting layer by shining UV light of a controlled wavelength onto the surface of the phase difference adjusting layer to unify the transition metal and N content in the mixture of the surface of the phase difference adjusting layer in the direction of the plane.

[0233] The phase difference setting layer can be treated with surface light by exposing the phase difference setting layer to a light source with a power of 2 to 10 mW / cm² for 5 to 20 minutes. 2 is irradiated with light of a wavelength of 200 nm or less.

[0234] The phase difference adjustment layer 21 can be heat-treated together with or separately from the UV irradiation. The heat treatment can be carried out using the heat generated by the UV irradiation or in separate processes.

[0235] The phase-difference adjustment layer 21 formed by the sputtering process may exhibit internal stress. Depending on the sputtering conditions, this internal stress can be compressive or tensile. The internal stress of the phase-difference adjustment layer can lead to substrate deformation, which may reduce the resolution of the photomask onto which the phase-difference adjustment layer is deposited. In this embodiment, the substrate deformation can be reduced by heat treatment of the phase-difference adjustment layer.

[0236] The protective layer can be formed by a heat treatment process after the phase-difference adjustment layer has been formed. During the heat treatment process, atmospheric gas can be introduced into the chamber to form a protective layer on the surface of the phase-difference adjustment layer 21. A protective layer can also be formed by the reaction of the surface of the phase-difference adjustment layer with atmospheric gas during the heat treatment process. However, the manufacturing process for the protective layer is not limited to this.

[0237] The heat treatment process can include a temperature increase step, a temperature maintenance step, a cooling step, and a protective layer formation step. The heat treatment process can be carried out by placing a mask blank, on whose surface a phase-difference setting layer has been formed, in a chamber and then heating it with a lamp.

[0238] By increasing the temperature, the temperature of the atmosphere in the heat treatment chamber can be raised to a target temperature of 150 to 500 °C.

[0239] During temperature maintenance, the atmospheric temperature in the chamber can be kept at the set temperature, and the pressure in the chamber can be set between 0.1 and 2.0 Pa. Temperature maintenance operation can be carried out for 5 to 60 minutes.

[0240] During the cooling process, the temperature in the chamber can be lowered from a specific temperature to room temperature.

[0241] The protective layer formation process is a process for creating a protective layer on the surface of the phase-shift film by introducing an atmospheric gas containing a reactive gas into the chamber after the cooling process is complete. The reactive gas can consist of O₂. The gas introduced into the chamber during protective layer formation can include at least one of the gases N₂, Ar, and He. Specifically, O₂ can be introduced into the chamber at a rate of 0.3 to 2.5 SLM (standard liters per minute). The protective layer formation process can be carried out for 10 to 60 minutes. The protective layer formation process can be carried out for 12 to 45 minutes.In such a case, the proportion of each element of the protective layer in the thickness direction can be adjusted so that the fluctuations in the optical properties of the entire phase-shift film caused by the formation of the protective layer are suppressed. Method for the production of light-protective film

[0242] The light-protective film can be formed in contact with the phase-shifting film or in contact with another thin film on the phase-shifting film.

[0243] The light-blocking layer can comprise a lower layer and an upper layer lying on top of the lower layer.

[0244] The sputtering process can be operated with direct current or high frequency.

[0245] Taking into account the composition of the light-shielding layer, a sputtering target and a sputtering gas can be selected during the sputtering process. If the light-shielding film consists of two or more layers, the composition of the sputtering gas applied to each layer can be different.

[0246] A chromium-containing target can be used as a sputtering target, and two or more targets can be used simultaneously. The chromium-containing target can contain chromium in an amount of 90 atomic percent or more. The chromium-containing target can contain chromium in an amount of 95 atomic percent or more. The chromium-containing target can contain chromium in an amount of 99 atomic percent or more.

[0247] In the case of sputtering gas, the composition of the sputtering gas can be adapted taking into account the composition of the elements from which the individual layers of the light-protective film consist, the density of the light-protective film, the optical properties, and the like.

[0248] The sputtering gas can consist of a reactive gas and an inert gas. By adjusting the proportions of the reactive and inert gases in the sputtering gas, the optical properties and density of the resulting light-shielding film can be controlled. The reactive gas can include CO2, O2, N2, NO2, and similar gases. In addition to the gases mentioned above, the reactive gas can also include other gases. The inert gas can include Ar, He, Ne, and similar gases. In addition to the gases mentioned above, the inert gas can also include other gases.

[0249] Once the lower layer of the light shielding film has formed, a sputtering gas containing Ar, N2, He, and CO2 can be introduced into the chamber. Specifically, a sputtering gas can be introduced where the sum of the CO2 and N2 flow rates is 40% or more of the total sputtering gas flow rate. In this case, the lower layer of the light shielding film can exhibit a desired optical property and contribute to a desired TFT2 value for the light shielding film.

[0250] Once the top layer of the light-shielding film has formed, a sputtering gas containing Ar and N₂ can be introduced into the chamber. Specifically, a sputtering gas can be introduced where the N₂ flow rate is 30% or more of the total sputtering gas flow rate. In such a case, it is possible to control the dimensional change in the thickness of the light-shielding film as a function of temperature changes.

[0251] Each gas that makes up the sputtering gas can be mixed and introduced into the sputtering chamber. Each gas that makes up the sputtering gas can also be introduced into the sputtering chamber individually through different inlets for each type.

[0252] A magnet can be placed in the chamber to check the uniformity of the crystal properties in the plane and the optical properties of the light-shielding film to be formed in the plane. The method of installing the magnet is omitted, as it overlaps with the case of the phase-shifting film. The magnet can be rotated at a speed of 50 to 200 rpm.

[0253] In sputtering, the T / S distance (the distance between the target and the substrate) and the angle between the substrate and the target can be adjusted simultaneously. When each layer of the light-blocking film is formed, the T / S distance can be 240 to 300 mm. The angle between the substrate and the target can be 20 to 30 degrees. In such a case, the film formation rate is stably controlled, and it is possible to suppress an excessive increase in the internal stress of the light-blocking film being formed.

[0254] In the sputtering process, the rotational speed of the substrate with the film-forming target surface can be adjusted. When each layer of the light-shielding film is formed, the rotational speed of the substrate with the film-forming target surface can be 2 to 50 rpm. The rotational speed of the substrate can be 10 to 40 rpm. In this case, each layer of the formed light-shielding film can further improve the uniformity of the optical properties and the TFT2 values ​​in the plane direction.

[0255] When the light shielding film 30 is formed, the intensity of electric power applied to the sputtering target can be adjusted. A discharge region comprising a plasma atmosphere in the chamber can be formed by supplying electrical energy to a target located in the sputtering chamber. By controlling the magnetic field strength and the magnet rotation speed while simultaneously adjusting the intensity of the sputtering current, the density of the light shielding film to be formed can be adjusted.

[0256] The intensity of the electrical power applied to the sputtering target during the formation of the lower layer of the light-shielding film can range from 0.5 to 2 kW. The electrical power intensity can range from 1.0 to 1.8 kW. The electrical power intensity can range from 1.2 to 1.5 kW. The intensity of the electrical power applied to the sputtering target during the formation of the upper layer of the light-shielding film can range from 1 to 3 kW. The electrical power intensity can range from 1.3 to 2.5 kW. The electrical power intensity can range from 1.5 to 2.0 kW. In such a case, it is possible to suppress excessive changes in the dimensions of the light-shielding film in terms of thickness, depending on the temperature change.

[0257] A spectroscopic ellipsometer can be integrated into the sputtering system. This makes it possible to control the film formation time and simultaneously monitor the optical properties of the light-shielding film being formed. The procedure for installing a spectroscopic ellipsometer in the sputtering system and measuring the optical properties of the light-shielding film is omitted here, as it overlaps with the description above.

[0258] Once the lower layer of the light-shielding film 30 is formed, sputtering can be carried out until the photon energy at a point with a phase difference of 140° between the P-wave and the S-wave of the reflected light, measured with a spectroscopic ellipsometer, is 1.6 to 2.2 eV. Once the lower layer of the light-shielding film 30 is formed, sputtering can be carried out until the photon energy at a point with a phase difference of 140° between the P-wave and the S-wave of the reflected light, measured with a spectroscopic ellipsometer, is 1.8 to 2.0 eV.

[0259] Once the top layer of the light-shielding film 30 is formed, sputtering can be carried out until the photon energy at the point where the phase difference between the P-wave and the S-wave of the reflected light, measured with a spectroscopic ellipsometer, is 140°, is between 1.7 and 3.2 eV. Once the top layer of the light-shielding film 30 is formed, sputtering can be carried out until the photon energy at a point with a phase difference of 140° between the P-wave and the S-wave of the reflected light, measured with a spectroscopic ellipsometer, is between 2.5 and 3.0 eV.

[0260] In such a case, the formed light-protective film can help to effectively block the exposure light. Photomask

[0261] A photomask (not shown) according to another embodiment of the present disclosure comprises a transparent substrate; a phase-shift pattern film arranged on the transparent substrate; and a light-protective film arranged on the phase-shift film.

[0262] The photomask has a TFT3 value of 0.25 µm / 100 °C or less, expressed by equation 3 below. TFT3=ΔpPMT2−T1

[0263] When the thermal change of a processed photomask, formed by processing the thickness of the transparent substrate of the photomask to 0.6 mm and removing the light-protective pattern film, is analyzed in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer is increased from T1 to T2, and the ΔpPM is a change in position of the upper surface of the phase-shift pattern film in the thickness direction at T2, based on a position of the upper surface of the phase-shift pattern film at T1.

[0264] A photomask (not shown) according to another embodiment of the present disclosure comprises a transparent substrate; a phase-shift pattern film arranged on the transparent substrate; and a light-shielding pattern layer arranged on the phase-shift film.

[0265] The photomask has a photon energy of the incident light at a point with a Del_1 of 0, expressed by equation 5 below, when PE1 has a value of 3.0 eV and PE2 has a value of 5.0 eV. Del_1=limΔPE→0(ΔpDPSΔPE)

[0266] In the equation above, 5, The pDPS value is a value of the phase difference between the P-wave and the S-wave of the reflected light when the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value resulting from subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° when the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, when the light shielding film is removed from the photomask and the surface of the phase-shift film is measured with a spectroscopic ellipsometer by applying an angle of incidence of 64.5°.

[0267] The photomask can be produced using the mask blank described above. Specifically, the photomask can be created by structuring the phase-shift film and the light-blocking film of the mask blank.

[0268] The descriptions of the thermal variation characteristics and the optical properties of the phase-shift pattern film and the light-protection film pattern film overlap with the descriptions of the thermal variation characteristics and the optical properties of the phase-shift film and the light-protection film described above and are therefore omitted.

[0269] The following section describes the exemplary implementations in more detail. Manufacturing example: Formation of a phase-shifting film and a light-protective film

[0270] Example 1: A transparent quartz substrate measuring 6 inches wide, 6 inches long, and 0.25 inches thick was placed in the chamber of the DC sputtering system. The target, containing molybdenum and silicon in an atomic ratio of 1:9, was positioned in the chamber with a T / S distance of 255 mm and an angle of 25 degrees between the substrate surface and the target surface. A magnet with a magnetic force of 40 mT was attached to the back of the target.

[0271] A sputtering gas with an Ar:N₂:He ratio of 9:52:39 was then introduced into the chamber. The electrical power of the sputtering unit was 2 kW, and the sputtering process was carried out with a rotating magnet. At this point, the magnet's rotational speed was increased from 100 rpm to a maximum of 150 rpm in increments of 10 rpm per minute. The area in which a phase-shift film would form was limited to the region defined by the width and length of 132 mm on the surface of the transparent substrate. The sputtering process was continued until the photon energy at a point with a De₁₁ value of 0, as measured by Equation 1, reached 2.0 eV on the phase-shift film during sputtering.

[0272] After sputtering, the surface of the phase-shift film of the mask blank was irradiated with excimer UV light at a wavelength of 172 nm. At this point, the optical power of the UV light was increased by 3 mW / cm². 2 per minute up to a maximum of 7mW / cm² 2 increased and for 5 minutes at 7mW / cm² 2 held.

[0273] The mask blank was then placed in a heat treatment chamber, annealed at 1 Pa, and subsequently cooled naturally. During the annealing process, the temperature was increased from room temperature by 50 °C per minute to a maximum of 400 °C and held at this maximum temperature for approximately 30 minutes. After natural cooling, oxygen gas (O2) was introduced into the heat treatment chamber at a rate of 1 SLM for 30 minutes. The temperature of the oxygen gas was approximately 300 °C.

[0274] A light-shielding film was sputtered onto the surface of the formed phase-shift film. Specifically, the substrate on which the phase-shift film was formed and a chromium target were arranged in the sputtering chamber such that the T / S distance was 255 mm and the angle between the substrate and the target was 25 degrees. A magnet with a magnetic field of 40 mT was attached to the back of the target.

[0275] A sputtering gas with a flow ratio of Ar:N₂:He:CO₂ = 19:11:34:37 ​​was introduced into the chamber. The electrical power for sputtering was then set to 1.35 kW, and the sputtering process was carried out until the photon energy at a point where the phase difference of the reflected light between the P-wave and the S-wave was 140° was between 1.8 and 2.0 eV, as measured from a lower layer of the light shielding film. Sputtering was performed while the magnet was rotated. During this process, the magnet's rotational speed was increased from 100 rpm to a maximum of 150 rpm at a rate of 10 rpm per minute.

[0276] After the lower layer of the light shielding film was formed, a sputtering gas with a flow ratio of Ar:N₂ = 57:43 was introduced into the chamber. Sputtering was then carried out until the photon energy at a point where the phase difference of the reflected light between the P-wave and the S-wave was 140° was between 2.75 and 2.95 eV, measured at the upper layer of the light shielding film. The sputtering was performed with an electrical power of 1.85 kW, and the magnet was rotated.

[0277] A total of two samples were prepared for film formation under the conditions described above.

[0278] Example 2: When manufactured under the same conditions as in Example 1, the magnetic force of a magnet was set to 45 mT when the phase-shift film and the light-shielding film were formed, and the formation time of the phase-shift film was defined as the time until the photon energy at a point with a Del_2 value of 0 according to Equation 1 became 1.89 eV.

[0279] Example 3: The production took place under the same conditions as in Example 1, but the composition of the sputtering gas was changed so that the ratio of Ar:N2:He=8:58:34 was when the phase-shift film was formed.

[0280] Example 4: While fabricated under the same conditions as in Example 1, the magnetic force of a magnet of 42 mT and a rotational speed of 150 rpm were applied during the formation of the phase-shift film and the light-shielding film. The formation of the lower layer of the light-shielding film was carried out until the photon energy at a point where the phase difference of the reflected light between the P-wave and the S-wave was 140° reached 1.9 eV. Furthermore, the electrical power for sputtering was set to 2.75 kW when the upper layer of the light-shielding film was formed, and sputtering was carried out until the photon energy at a point where the phase difference of the reflected light between the P-wave and the S-wave was 140° reached 1.9 eV.

[0281] Example 5: While it was manufactured under the same conditions as in Example 4, the magnetic force of a magnet was set to 48 mT, and the formation of the phase-shift foil was carried out until the photon energy at a point with the Del_2 value of 0 became 1.89 eV.

[0282] Example 6: It was produced under the same conditions as in Example 4, except that the ratio of the gas contained in the sputtering gas during the formation of the phase-shift film was changed to Ar:N2:He = 8:58:34. Additionally, a magnetic force of 37 mT was applied during the formation of the phase-shift film and the light-shielding film.

[0283] Comparative example 1: The manufacturing process took place under the same conditions as in example 1. However, a magnetic force of 60 mT and a rotational speed of 100 rpm were applied during the production of the phase-shifting film and the light-protective film, and the phase-shifting film was not irradiated with UV light or subjected to any heat treatment.

[0284] Comparative example 2: It was produced under the same conditions as in comparative example 1, applying a magnetic force of 20 mT from a magnet.

[0285] Comparative example 3: The manufacturing process took place under the same conditions as in example 4. However, a magnetic force of 63 mT and a rotational speed of 100 rpm were applied during the production of the phase-shifting film and the light-protective film, and the phase-shifting film was not irradiated with UV light or subjected to any heat treatment.

[0286] Comparative Example 4: The fabrication took place under the same conditions as in Comparative Example 3, however, the ratio of the gases contained in the sputtering gas during the formation of the phase-shift film was changed to Ar:N2:He = 8:58:34. Furthermore, a magnetic force of 23 mT was applied during the formation of the phase-shift film and the light-shielding film. Example of evaluation: Measurement of temperature fluctuations

[0287] The mask blanks of Examples 1 to 3 and of Comparative Examples 1 and 2 were cut to a size of 1 cm x 1 cm, and an area opposite the area on which the phase-shift film was formed within the transparent substrate was etched into the cut mask blanks. The thickness of the transparent substrate after etching was 0.6 mm.

[0288] After the transparent substrate was etched, the TFT2 values ​​of the examples and comparison examples were measured using a thermomechanical analyzer. After placing the samples of each example and comparison example into the TA INSTRUMENT Q400 thermomechanical analyzer, a tip was applied to a sample. The peak load was then set to 0.05 N, the temperature increased to 10 °C / min, the measurement temperature range set to 30 to 200 °C, and the measurement was performed.

[0289] For each sample of the examples and comparison examples where the TFT2 value was measured, the light-shielding film was removed. Specifically, the light-shielding film was removed by etching with a chlorine-based gas as the etchant. The TFT1 values ​​of the examples and comparison examples were then measured using a thermomechanical analyzer. The measurement conditions are the same as those used for measuring the TFT2 value.

[0290] A diagram of the thermal variation in the direction of the thickness of the phase-shift foil as a function of temperature of Example 1 was presented in Fig. 4 shown, and a diagram of the thermal variation in the direction of the thickness of the phase-shift film as a function of temperature of Example 2 was shown in Fig. Figure 5 is shown. Furthermore, the calculation results for TFT1 and TFT2 are listed in Table 1 below. Example of evaluation: Optical properties of a phase-shift film, measured with an ellipsometer

[0291] The light-protective film on the samples of the examples and comparison examples was removed by etching. The del_2 value distribution, phase difference, and transmittance were measured for each example and comparison example using a spectroscopic ellipsometer (MPM193 product from LASERTEC). For the phase difference and transmittance measurements, the wavelength of the exposure light was set to 193 nm. The measurement results for each example and comparison example are listed in Tables 2 and 3 below. Furthermore, in Fig. 6 to Fig. 15 diagrams are shown, illustrating the distribution of the DPS and Del_2 values ​​measured in examples 4 to 6 and comparison examples 3 and 4. Example of evaluation: Contrast and CD value measurement

[0292] After a photoresist film was formed on the surface of the phase-shift film of each sample in the examples and comparison examples, a dense rectangular pattern was exposed onto the surface of the photoresist film using the Nuflare EBM 9000 model. The CD target of the square pattern was set to 400 nm (4X). Once a pattern had formed on the photoresist film of each sample, the light-shielding film and the phase-shift film were etched according to the developed pattern shape using the Applied Materials Tetra X model. The photoresist pattern was then removed.

[0293] The contrast and normalized CD values ​​of the patterns developed by the exposure process were measured and calculated using the CARL ZEISS AIMS 32 model for each sample and reference sample, which included the phase-shift pattern foil. For the measurements and calculations, the numerical aperture (NA) was set to 1.35, the illumination system to a 30-fold cross-pole, an outer sigma of 0.8, and an inner / outer sigma ratio of 85%. The measured data are listed in Table 3 below. Evaluation example: Measurement and assessment of the content of the individual elements in the direction of the thickness of the protective layer

[0294] For the samples in Examples 4 to 6 and the comparison examples 3 and 4, the content of each element was measured in the direction of the thickness of the protective layer. Specifically, the analyzer type / channel was a 180-degree dual-focus hemispherical analyzer / 120-channel, the X-ray light source was an Al Ka ​​microfocus, the power was 1 keV, the operating pressure was 1E-7 mbar, and the gas was Ar to measure the content of each element in the thickness direction of the protective layer using the K-alpha model available from THERMO SCIENTIFIC.

[0295] If the protective layer included an area where the nitrogen to oxygen content ratio in the thickness direction was 0.4 to 2, and the area had a thickness of 30 to 80% of the total thickness of the protective layer, it was rated as O; if the area had a thickness of less than 30% or more than 80% of the total thickness of the protective layer, it was rated as X. The measurement results are listed in Table 3 below. [Table 1] T1(°C) T2(°C) ΔPM(µm) ΔPC(µm) TFT1 (µm / 100℃) TFT2 (µm / 100°C) Example 1 30 200 0,2874 0,1075 0,1691 0,0632 50 150 0,143 0,210 0,143 0,210 50 100 0,001 0,032 0,003 0,094 Example 2 30 200 0,3870 0,268 0,2276 0,158 50 150 0,190 0,231 0,190 0,231 Example 3 30 200 0,319 0,227 0,188 0,133 50 150 0,185 0,223 0,185 0,223 Example 4 - - - - - - Example 5 - - - - - - Example 6 Comparison example 1 30 200 0,452 0,446 0,266 0,262 50 150 0,311 0,298 0,311 0,298 Comparison example 2 30 200 0,522 0,463 0,307 0,272 50 150 0,276 0,296 0,276 0,296 Comparison example 3 Comparison example 4 [Table 2] Photon energy of the incident light at the point where the Del_2 value is 0, when PE1 is 1.5 eV and PE2 is 3 eV (eV) Photon energy of the incident light at the point where the Del_2 value is 0, when PE1 is 3eV and PE2 is 5eV (eV) Average value of Del_2 when PE1 is 1.5eV and PE2 is S* (° / eV) Average value of Del_2 when PE1 is S* and PE2 is B* (° / eV) Average value of Del 2 when PE1 is B* and PE2 is 5eV (° / eV) Maximum value of Del_2 when PE1 is 1.5eV and PE2 is 5eV Example 1 2,00 4,44 - - - - Example 2 1,89 4,31 - - - - Example 3 2,09 4,65 - - - - Example 4 2,02 4,46 86,5 -57,3 91,6 157,5 Example 5 1,95 4,28 82,1 -58,5 102,2 187,3 Example 6 2,09 4,58 94,2 -57,0 84,0 143,7 Comparative example 1 1,65 3,84 - - - - Comparison example 2 2,17 4,80 - - - - Comparison example 3 1,71 3,79 75,0 -66,8 -21,8 320,0 Comparison example, case 4 2,15 4,65 98,3 -53,5 58,1 103,5 * S* is the minimum value among the photon energies of the incident light at a point with a Del_2 value of 0. * B* is the maximum value of the photon energy of the incident light at a point with a Del_2 value of 0. [Table 3] Permeability (%) Phase difference (°) Normalized contrast Normalized CD Evaluation of the composition of the individual elements of the protective layer in the thickness direction Example 1 6,1 178,5 1,000 0,99 - Example 2 5,4 186,1 0,989 1,01 - Example 3 6,9 172,4 0,959 1,03 - Example 4 6,1 175,7 1,000 1,00 O Example 5 5,6 181,0 0,992 1,01 O Example 6 6,4 172,6 0,977 1,02 O Comparative example 1 3,4 209,1 0,929 1,06 - Comparative example 2 7,8 166,0 0,883 1,10 - Comparative example 3 3,3 205,3 0,918 1,05 X Comparative example 4 7,4 162,0 0,895 1,08 X

[0296] In Table 1, all TFT1 and TFT2 values ​​for each measurement condition of Examples 1 to 3 showed a value of 0.25 µm / 100 °C or less, but all TFT1 and TFT2 values ​​for each measurement condition of Comparison Examples 1 and 2 showed a value of more than 0.25 µm / 100 °C.

[0297] In Table 3, the transmittance of examples 1 to 3 ranged from 5.4 to 6.9%, and the phase difference ranged from 170 to 190°, but comparison examples 1 and 3 had a transmittance of less than 4% and a phase difference of 200° or more, and comparison examples 2 and 4 had a transmittance of 7% or more and a phase difference of less than 170°. This indicates that the phase-shift film with the adapted Del_2 value distribution exhibits optical properties close to the desired transmittance (6%) and phase difference (180°) for short-wavelength exposure light.

[0298] Examples 1 to 6 showed a normalized contrast of 0.95 or more and a normalized CD value of less than 1.05, while comparison examples 1 to 4 showed a normalized contrast of less than 0.93 and a normalized CD value of 1.05 or more.

[0299] When evaluating the composition for each element in the direction of the thickness of the protective layer, examples 4 to 6 were rated O, while comparison examples 3 and 4 were rated X.

[0300] Although the exemplary embodiments have been described in detail, the scope of the present invention is not limited to these, and modifications and changes made by those skilled in the art using the basic concept of the present invention as defined in the following claims are within the scope of protection of the present invention. Reference symbol list 100 mask blanks 10 transparent substrate 20 Phase Shift Slide 21 Phase Difference Adjustment Layer 22 Protective layer 30 Light-protective film θ Angle of incidence N Normal line L i incident light L r Reflected light P-wave component of the incident light S-wave component of the incident light P' P-wave component of the reflected light S' S-wave component of reflected light Δ Phase difference between P-wave and S-wave of the reflected light

Claims

[1] A mask blank, comprising: a transparent substrate; a phase-shift film arranged on the transparent substrate; and a light-protective film that is arranged on the phase-shifting film; where a TFT1 value expressed by Equation 1 below is 0.25 µm / 100 °C or less; TFT1=ΔPMT2−T1 where, if the thermal change of the machined mask blank, which is formed by machining the thickness of the transparent substrate of the mask blank to 0.6 mm and removing the light-protective film, is analyzed in a thermomechanical analyzer, the measuring temperature of the thermomechanical analyzer is increased from T1 to T2, and ΔPM is a change in the position of the upper surface of the phase shift foil in the thickness direction at T2, based on a position of the upper surface of the phase shift foil at T1. [2] The mask blank according to claim 1, wherein the TFT1 value is 0.2 µm / 100 °C or less when T1 is 50 °C and T2 is 80 °C. [3] The mask blank according to claim 1, wherein the TFT1 value is 0.2 µm / 100 °C or less when T1 is 50 °C and T2 is 150 °C. [4] The mask blank according to claim 1, wherein the mask blank has a photon energy of 1.8 to 2.14 eV at a point with a Del_2 value of 0 according to equation 3 below, when PE1 has a value of 1.5 eV and PE2 has a value of 3.0 eV; Del_2=limΔPE→0(ΔDPSΔPE) where in equation 3, The DPS value is determined when the light-shielding film is removed from the mask blank and the surface of the phase-shift film is measured with a spectroscopic ellipsometer by an angle of incidence of 64.5°, the phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, and The PE value is a photon energy of the incident light in a range between the PE1 value and the PE2 value. [5] The mask blank according to claim 1, wherein the mask blank has a photon energy of 3.8 to 4.64 eV at a point with a Del_2 value of 0 according to equation 3 below, when PE1 has a value of 3 eV and PE2 has a value of 5 eV. Del_2=limΔPE→0(ΔDPSΔPE) where in equation 3, The DPS value is determined when the light-shielding film is removed from the mask blank and the surface of the phase-shift film is measured with a spectroscopic ellipsometer by an angle of incidence of 64.5°, the phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, and The PE value is a photon energy of the incident light in a range between the PE1 value and the PE2 value. [6] A mask blank, comprising: a transparent substrate; a phase-shift film arranged on the transparent substrate; and a light-shielding film arranged on the phase-shift film; wherein a photon energy of the incident light at a point with a Del_2 value of 0 according to Equation 3 below is 3.8 eV to 4.64 eV when PE1 has a value of 3.0 eV and PE2 has a value of 5.0 eV; Del_2=limΔPE→0(ΔDPSΔPE) where in equation 3, The DPS value is determined when the light-shielding film is removed from the mask blank and the surface of the phase-shift film is then measured with a spectroscopic ellipsometer by an angle of incidence of 64.5°, the phase difference between the P-wave and the S-wave of the reflected light if the phase difference between the P-wave and the S-wave of the reflected light is 180° or less, or a value subtracting the phase difference between the P-wave and the S-wave of the reflected light from 360° if the phase difference between the P-wave and the S-wave of the reflected light is more than 180°, and The PE value is a photon energy of the incident light in a range between the PE1 value and the PE2 value. [7] The mask blank according to claim 6, wherein the photon energy of the incident light at the point where the Del_2 value is 0 is 1.8 to 2.14 eV when the PE1 value is 1.5 eV and the PE2 value is 3.0 eV. [8] The mask blank according to claim 6, wherein an average value of the Del_2 value is 78 to 98 ° / eV when the PE1 value is 1.5 eV and the PE2 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0. [9] The mask blank according to claim 6, wherein an average value of the Del_2 value is -65 to -55 ° / eV when the PE1 value is the minimum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0 and the PE2 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0. [10] The mask blank according to claim 6, wherein an average value of the Del_2 value is 60 to 120 ° / eV when the PE1 value is the maximum value within the photon energy values ​​of the incident light at a point with the Del_2 value of 0, and when the PE2 value is 5.0 eV. [11] The mask blank according to claim 6, wherein the maximum value of the Del_2 value is 105 to 300 ° / eV when the PE1 value is 1.5 eV and the P2 value is 5.0 eV. [12] The mask blank according to claim 11, wherein the photon energy at a point with the maximum value of the Del_2 value is 4.5 eV or more. [13] The mask blank according to claim 1, wherein the phase shift film comprises a phase difference setting layer and a protective layer arranged on the phase difference setting layer, wherein the phase-shifting foil contains a transition metal, silicon, oxygen and nitrogen, wherein the phase difference adjustment layer comprises nitrogen in an amount of 40 to 60 atomic percent, the protective layer contains nitrogen in an amount of 20 to 40 atomic percent, wherein the protective layer comprises an area in which the ratio of nitrogen content to oxygen content in the thickness direction is 0.4 to 2, and the area has a thickness of 30 to 80% compared to the total thickness of the protective layer. [14] The mask blank according to claim 13, wherein the ratio between the thickness of the protective layer and the thickness of the phase-shifting film is 0.04 to 0.

09. [15] A photomask, comprising: a transparent substrate; a phase-shifting film arranged on the transparent substrate; and a light-protective film that is arranged on the phase-shifting film; where a TFT1 value expressed by equation 4 below is 0.25 µm / 100 °C or less; TFT3=ΔpPMT2−T1 where, if the thermal change of the machined mask blank, which is formed by machining the thickness of the transparent substrate of the mask blank to 0.6 mm and removing the light-protective film, is analyzed in a thermomechanical analyzer, the measuring temperature of the thermomechanical analyzer is increased from T1 to T2, and ΔpPM is a change in the position of the upper surface of the phase shift pattern foil in the thickness direction at T2 based on the position of the upper surface of the phase shift pattern foil at T1.