Blank mask and light mask using it

Abstract

This invention relates to a blank mask and a photomask utilizing the same. Embodiments relate to blank masks, etc., which include: a transparent substrate, a phase-shifting film disposed on the transparent substrate, and a light-shielding film disposed on the phase-shifting film. The TFT1 value of the blank mask, expressed by the following Formula 1, is 0.25 μm / 100 °C or less. Semiconductor devices with fine linewidths can be easily manufactured using such blank masks, etc. [Formula 1] When analyzing the thermal fluctuations of the processed blank mask formed by processing the transparent substrate of the blank mask to a thickness of 0.6 mm and removing the light-shielding film in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer rises from T1 to T2, and ΔPM is the change in position of the upper surface of the phase-shifting film in the thickness direction at T2, with the upper surface of the phase-shifting film at T1 as a reference.

Description

Technical Field

[0001] The embodiments relate to a blank mask and a photomask utilizing the same. Background Technology

[0002] Due to the high integration of semiconductor devices, there is a need for miniaturized circuit patterns. Therefore, photolithography, a technique that uses photomasks to develop circuit patterns on the surface of a wafer, has become increasingly important.

[0003] To develop intricate circuit patterns, short-wavelength exposure light sources are required in the exposure process. Recently used exposure light sources include ArF excimer lasers (wavelength 193 nm).

[0004] In addition, photomasks include binary masks and phase-shift masks.

[0005] A binary photomask has a structure in which a light-shielding layer pattern is formed on a transparent substrate. In a binary photomask, exposure light passes through a light-transmitting portion (excluding the light-shielding layer) on the patterned surface, while the light-shielding portion (including the light-shielding layer) blocks the exposure light, thereby exposing the pattern on a resist film on the wafer surface. However, in a binary photomask, as the pattern becomes finer, it may be difficult to miniaturize the pattern due to light diffraction at the edges of the light-transmitting portion during the exposure process.

[0006] Phase-shifting masks include Levenson type, Outrigger type, and Half-tone type. Half-tone type phase-shifting masks have a structure in which a pattern formed by a semi-transparent film is formed on a transparent substrate. In a half-tone type phase-shifting mask, on the patterned surface, exposure light passes through the transparent portion excluding the semi-transparent layer, while attenuated exposure light passes through the semi-transparent portion including the semi-transparent layer. The attenuated exposure light has a phase difference compared to the exposure light passing through the transparent portion. Therefore, the diffracted light generated at the edge of the transparent portion cancels out the exposure light passing through the semi-transparent portion, allowing the phase-shifting mask to form finer micro-patterns on the wafer surface.

[0007] Existing technical documents

[0008] Patent Literature

[0009] Korean Patent No. 10-1360540

[0010] U.S. Patent Publication No. 2004-0115537

[0011] Japanese Patent Publication No. 2018-054836 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] The embodiment provides a blank mask that can easily form fine patterns and a photomask using the same.

[0014] means for solving problems

[0015] One embodiment of the blank mask includes: a transparent substrate, a phase shift film disposed on the transparent substrate, and a light-shielding film disposed on the phase shift film; the TFT1 value, expressed by the following formula 1, is 0.25 μm / 100 °C or less;

[0016] [Formula 1]

[0017]

[0018] When analyzing the thermal fluctuations of the processed blank mask formed by processing the transparent substrate of the blank mask to a thickness of 0.6 mm and removing the light-shielding film in a thermomechanical analyzer, the measured temperature of the thermomechanical analyzer rises from T1 to T2, and ΔPM is the change in position of the upper surface of the phase shift film in the thickness direction at T2, with the upper surface of the phase shift film at T1 as a reference.

[0019] In the blank mask, when T1 is 50°C and T2 is 80°C, the TFT1 value can be below 0.2μm / 100°C.

[0020] In the blank mask, when T1 is 50°C and T2 is 150°C, the TFT1 value can be below 0.2μm / 100°C.

[0021] In the blank mask, the TFT2 value, as expressed by the following formula 2, can be below 0.25 μm / 100 °C.

[0022] [Equation 2]

[0023]

[0024] Specifically, when analyzing the thermal fluctuations of the processed blank mask formed by processing the thickness of the blank mask to 0.6 mm in a thermomechanical analyzer, the measured temperature of the thermomechanical analyzer rises from T1 to T2, and ΔPC is the change in position of the upper surface of the light-shielding film in the thickness direction at T2, with the upper surface of the light-shielding film at T1 as a reference.

[0025] In the blank mask, when PE1 is 1.5 eV and PE2 is 3.0 eV, the photon energy at the point where Del_2 is 0 according to Equation 3 is between 1.8 eV and 2.14 eV:

[0026] [Formula 3]

[0027]

[0028] In Equation 3, when the light-shielding film is removed from the blank mask and the surface of the phase-shifting film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°.

[0029] The PE value is the photon energy of the incident light within the range of the PE1 value to the PE2 value.

[0030] In the blank mask, when PE1 is 3eV and PE2 is 5eV, the photon energy at the point where Del_2 is 0 can be between 3.8eV and 4.64eV.

[0031] In the blank mask, when PE1 is 3.0 eV and PE2 is 5.0 eV, the photon energy of the incident light at the point where Del_2 is 0, as expressed by Equation 3 above, can be 3.8 to 4.64 eV.

[0032] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is 3.0 eV, the photon energy of the incident light at the point where the Del_2 value is 0 can be 1.8 to 2.14 eV.

[0033] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is the minimum of the photon energies of the incident light at the point where the Del_2 value is 0, the average value of the Del_2 value can be 78 to 98° / eV.

[0034] In the blank mask, when the PE1 value is the minimum photon energy of the incident light at the point where the Del_2 value is 0, and the PE2 value is the maximum photon energy of the incident light at the point where the Del_2 value is 0, the average value of the Del_2 value can be -65 to -55° / eV.

[0035] In the blank mask, when the PE1 value is the maximum value of the photon energy of the incident light at the point where the Del_2 value is 0, and the PE2 value is 5.0 eV, the average value of the Del_2 value can be 60 to 120° / eV.

[0036] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of the Del_2 value can be 105 to 300° / eV.

[0037] In the blank mask, the photon energy at the point where the Del_2 value is at its maximum can be above 4.5 eV.

[0038] The phase shift film can protect the phase difference adjustment layer and the protective layer located on the phase difference adjustment layer.

[0039] The phase-shifting film may contain transition metals, silicon, oxygen, and nitrogen.

[0040] The phase difference adjustment layer may contain 40 to 60 atomic percent nitrogen.

[0041] The protective layer may contain 20 to 40 atomic percent nitrogen.

[0042] The protective layer includes a region in which the ratio of nitrogen content to oxygen content in the thickness direction is 0.4 to 2, and the thickness of the region can be 30 to 80% of the overall thickness of the protective layer.

[0043] The ratio of the thickness of the protective layer to the thickness of the phase-shifting film can be from 0.04 to 0.09.

[0044] The thickness of the protective layer can be The above and the following.

[0045] The phase difference adjustment layer can have a refractive index of 2 to 4 for light with a wavelength below 200 nm, and an extinction coefficient of 0.3 to 0.7 for light with a wavelength below 200 nm.

[0046] The light-shielding film contains chromium, oxygen, nitrogen, and carbon, and may contain 44 to 60 atomic percent of the chromium.

[0047] The blank mask comprises a multilayer film, which includes a phase-shifting film and the light-shielding film. The optical density of the multilayer film for light with wavelengths below 200 nm can be 3 or higher.

[0048] Another embodiment of the blank mask includes: a transparent substrate; a phase shifting film disposed on the transparent substrate; and a light-shielding film disposed on the phase shifting film.

[0049] In the blank mask, when PE1 is 3.0 eV and PE2 is 5.0 eV, the photon energy of the incident light at the point where Del_2 is 0, as expressed by Equation 3, is 4.0 to 5.0 eV.

[0050] [Formula 3]

[0051]

[0052] In Equation 3, when the light-shielding film is removed from the blank mask and the surface of the phase-shifting film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°. The PE value is the photon energy of the incident light in the range of PE1 to PE2.

[0053] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is 3.0 eV, the photon energy of the incident light at the point where the Del_2 value is 0 can be 1.7 to 2.3 eV.

[0054] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is the minimum of the photon energies of the incident light at the point where the Del_2 value is 0, the average value of the Del_2 value can be 85 to 98° / eV.

[0055] In the blank mask, when the PE1 value is the minimum photon energy of the incident light at the point where the Del_2 value is 0, and the PE2 value is the maximum photon energy of the incident light at the point where the Del_2 value is 0, the average value of the Del_2 value can be -65 to -55° / eV.

[0056] In the blank mask, when the PE1 value is the maximum value of the photon energy of the incident light at the point where the Del_2 value is 0, and the PE2 value is 5.0 eV, the average value of the Del_2 value can be 60 to 120° / eV.

[0057] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of the Del_2 value can be 105 to 300° / eV.

[0058] In the blank mask, the photon energy at the point where the Del_2 value is at its maximum can be above 4.5 eV.

[0059] In the blank mask, the TFT1 value can be below 0.25 μm / 100 °C.

[0060] In the blank mask, when T1 is 50°C and T2 is 80°C, the TFT1 value can be below 0.2μm / 100°C.

[0061] In the blank mask, when T1 is 50°C and T2 is 150°C, the TFT1 value can be below 0.2μm / 100°C.

[0062] In the blank mask, the TFT2 value can be below 0.25 μm / 100 °C.

[0063] The phase shift film may include a phase difference adjustment layer and a protective layer located on the phase difference adjustment layer.

[0064] The phase-shifting film may contain transition metals, silicon, oxygen, and nitrogen.

[0065] The phase difference adjustment layer may contain 40 to 60 atomic percent nitrogen.

[0066] The protective layer may contain 20 to 40 atomic percent nitrogen.

[0067] The protective layer includes a region in which the ratio of nitrogen content to oxygen content in the thickness direction is 0.4 to 2, and the thickness of the region can be 30 to 80% of the overall thickness of the protective layer.

[0068] The ratio of the thickness of the protective layer to the thickness of the phase-shifting film can be from 0.04 to 0.09.

[0069] The thickness of the protective layer can be The above and the following.

[0070] The phase difference adjustment layer can have a refractive index of 2 to 4 for light with a wavelength below 200 nm, and an extinction coefficient of 0.3 to 0.7 for light with a wavelength below 200 nm.

[0071] The light-shielding film contains chromium, oxygen, nitrogen, and carbon, and may contain 44 to 60 atomic percent of the chromium.

[0072] The blank mask comprises a multilayer film, which includes a phase-shifting film and the light-shielding film. The optical density of the multilayer film for light with wavelengths below 200 nm can be 3 or higher.

[0073] Another embodiment of the photomask includes: a transparent substrate; a phase-shifting pattern film disposed on the transparent substrate; and a light-shielding pattern film disposed on the phase-shifting pattern film.

[0074] The TFT3 value of the photomask, as expressed by Equation 4, is below 0.25 μm / 100 °C.

[0075] [Formula 4]

[0076]

[0077] When the thickness of the transparent substrate of the photomask is processed to 0.6 mm and the thermal fluctuation of the processed photomask is formed by removing the light-shielding pattern film, the measurement temperature of the thermomechanical analyzer rises from T1 to T2. The ΔpPM is the change in position of the upper surface of the phase-shifting pattern film in the thickness direction at T2, with the upper surface of the phase-shifting pattern film at T1 as a reference.

[0078] Another embodiment of the photomask includes: a transparent substrate; a phase-shifting pattern film disposed on the transparent substrate; and a light-shielding pattern film disposed on the phase-shifting pattern film.

[0079] In the photomask, when PE1 is 3.0 eV and PE2 is 5.0 eV, the photon energy of the incident light at the point where Del_1 is 0, as expressed by Equation 5, can be 4.0 to 5.0 eV.

[0080] [Formula 5]

[0081]

[0082] In Equation 5, when the light-blocking pattern film is removed from the photomask and the surface of the phase-shifting pattern film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the pDPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the pDPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°.

[0083] The PE value is the photon energy of the incident light within the range of PE1 to PE2.

[0084] Another embodiment of the semiconductor device manufacturing apparatus includes: a light source; and a photomask such that light incident from the light source selectively passes through and exits onto a semiconductor wafer.

[0085] The photomask includes: a transparent substrate; a phase-shifting pattern film disposed on the transparent substrate; and a light-shielding pattern film disposed on the phase-shifting pattern film.

[0086] The TFT3 value of the photomask, as expressed by Equation 4, is below 0.25 μm / 100 °C.

[0087] [Formula 4]

[0088]

[0089] Specifically, when analyzing the thermal fluctuations of the processed photomask formed by processing the transparent substrate of the photomask to a thickness of 0.6 mm and removing the light-shielding pattern film in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer rises from T1 to T2. The ΔpPM is the position change of the upper surface of the phase-shifting pattern film in the thickness direction at T2, with the upper surface of the phase-shifting pattern film at T1 as a reference.

[0090] Another embodiment of the semiconductor device manufacturing apparatus includes: a light source; and a photomask such that light incident from the light source selectively passes through and exits onto a semiconductor wafer.

[0091] In the photomask, when PE1 is 3.0 eV and PE2 is 5.0 eV, the photon energy of the incident light at the point where Del_1 is 0, as expressed by Equation 5, is 4.0 to 5.0 eV.

[0092] [Formula 5]

[0093]

[0094] In Equation 5, when the light-blocking pattern film is removed from the photomask and the surface of the phase-shifting pattern film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the pDPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the pDPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°.

[0095] The PE value is the photon energy of the incident light within the range of PE1 to PE2.

[0096] Another embodiment of a blank mask includes: a transparent substrate, a phase shift film disposed on the transparent substrate, and a light-shielding film disposed on the phase shift film; the TFT1 value, represented by the following formula 1, is 0.25 μm / 100 °C or less;

[0097] [Formula 1]

[0098]

[0099] When analyzing the thermal fluctuations of the processed blank mask formed by processing the transparent substrate of the blank mask to a thickness of 0.6 mm and removing the light-shielding film in a thermomechanical analyzer, the measurement temperature of the thermomechanical analyzer rises from T1 to T2. The ΔPM is the change in position of the upper surface of the phase-shifting film in the thickness direction at T2, with the upper surface of the phase-shifting film at T1 as a reference.

[0100] When PE1 is 1.5 eV and PE2 is 3.0 eV, the photon energy at the point where Del_2 is 0 according to Equation 3 is between 1.8 eV and 2.14 eV:

[0101] [Formula 3]

[0102]

[0103] In Equation 3, when the light-shielding film is removed from the blank mask and the surface of the phase-shifting film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°. The PE value is the photon energy of the incident light within the range of the PE1 value to the PE2 value.

[0104] Another embodiment of a blank mask includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light-shielding film disposed on the phase shift film, wherein when the PE1 value is 3.0 eV and the PE2 value is 5.0 eV, the photon energy of the incident light at the point where Del_2 is 0, as expressed by the following formula 3, is 3.8 eV to 4.64 eV;

[0105] [Formula 3]

[0106]

[0107] In Equation 3, when the light-shielding film is removed from the blank mask and the surface of the phase-shifting film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°. The PE value is the photon energy of the incident light in the range of PE1 to PE2. When the PE1 value is 1.5 eV and the PE2 value is 3.0 eV, the photon energy of the incident light at the point where the Del_2 value is 0 is 1.8 eV to 2.14 eV.

[0108] In another embodiment, the photomask is made from the aforementioned blank mask.

[0109] Invention Effects

[0110] The embodiments can provide a blank mask that can easily form fine patterns and a photomask using the same. Attached Figure Description

[0111] Figure 1 This is a conceptual diagram illustrating a blank mask of one embodiment in this specification.

[0112] Figure 2 This is a conceptual diagram illustrating a blank mask of another embodiment in this specification.

[0113] Figure 3 This is a conceptual diagram illustrating the principle of measuring the phase difference between the P-wave and S-wave of reflected light from a phase-shifting film using an elliptic polarization spectrometer.

[0114] Figure 4 This is a graph showing the thermal fluctuation values ​​of the phase-shifting film of Example 1 in the thickness direction according to temperature.

[0115] Figure 5 This is a graph showing the thermal fluctuation values ​​of the phase-shifting film of Example 2 in the thickness direction according to temperature.

[0116] Figure 6 This is a graph showing the distribution of DPS values ​​based on photon energy, as measured in Example 4.

[0117] Figure 7 This is a graph showing the distribution of the Del_2 values ​​of photon energy measured in Example 4.

[0118] Figure 8 This is a graph showing the distribution of DPS values ​​based on photon energy, as measured in Example 5.

[0119] Figure 9This is a graph showing the distribution of the Del_2 values ​​of photon energy measured in Example 5.

[0120] Figure 10 This is a graph showing the distribution of DPS values ​​based on photon energy, as measured in Example 6.

[0121] Figure 11 This is a graph showing the distribution of the Del_2 values ​​of photon energy measured in Example 6.

[0122] Figure 12 This is a graph showing the distribution of DPS values ​​based on photon energy, as measured in Comparative Example 3.

[0123] Figure 13 This is a graph showing the distribution of the Del_2 values ​​of photon energy based on the measurements of Comparative Example 3.

[0124] Figure 14 This is a graph showing the distribution of DPS values ​​based on photon energy, as measured in Comparative Example 4.

[0125] Figure 15 This is a graph showing the distribution of the Del_2 values ​​of photon energy based on the measurements of Comparative Example 4.

[0126] Description of Reference Numerals

[0127] 100: Blank Mask

[0128] 10: Transparent substrate

[0129] 20: Phase Shifting Film

[0130] 21: Phase Difference Adjustment Layer

[0131] 22: Protective layer

[0132] 30: Light-shielding film

[0133] 200: Photomask

[0134] 300: Light source

[0135] 400: Lens

[0136] 500: Semiconductor wafers

[0137] 1000: Semiconductor device manufacturing equipment; θ: Angle of incidence.

[0138] N: Normal line

[0139] Li: Incident light

[0140] Lr: Reflected light

[0141] P: P-wave component of incident light

[0142] S: S-wave component of incident light

[0143] P': P-wave component of reflected light

[0144] S': S-wave component of reflected light

[0145] △: The phase difference between the P-wave and S-wave of the reflected light. Detailed Implementation

[0146] The embodiments are described in detail below to enable those skilled in the art to readily implement them. However, the embodiments can be implemented in various different forms and are not limited to the embodiments described herein.

[0147] The terms “about”, “substantially”, etc., used in this specification to indicate degree, when referring to inherent manufacturing and material tolerances in their intended meaning, are interpreted as values ​​or close to those values, and are intended to prevent unethical individuals from misusing the disclosures relating to accurate or absolute values ​​disclosed to aid in understanding this invention.

[0148] Throughout the entire specification of this invention, the term "combination thereof" in the Markush form of the expression means a mixture or combination of one or more of the groups of constituent elements described in the Markush form of the expression, and thus indicates that it includes one or more of the groups of said constituent elements.

[0149] Throughout the entire specification of this invention, the reference to "A and / or B" means "A, B or A and B".

[0150] Throughout the entire specification of this invention, unless otherwise stated, the terms "first," "second," or "A," "B," etc., are used to distinguish the same terms.

[0151] In this specification, B being on A means that B is on A or that B is on A and there is another layer between A and B, and should not be interpreted as B being in contact with the surface of A.

[0152] In this specification, unless otherwise stated, singular expressions should be interpreted as having the singular or plural meaning as interpreted in the context.

[0153] In this specification, the light-transmitting area refers to the area on a transparent substrate that does not include a phase-shifting film in the patterned photomask surface, allowing exposure light to pass through. The semi-transparent area refers to the area that includes a phase-shifting film, allowing attenuated exposure light to pass through.

[0154] In this specification, the incident angle refers to the angle formed by the incident light of the elliptically polarized spectrometer and the normal line of the phase-shifting film.

[0155] In this instruction manual, room temperature refers to 20°C to 25°C.

[0156] Semiconductor devices can be manufactured by forming an exposure pattern on a semiconductor wafer. Specifically, a photomask including a designed pattern is placed on a semiconductor wafer whose surface is coated with a resist layer, and then exposure is performed using a light source. In this case, the resist layer of the semiconductor wafer is treated with a developer to have the designed pattern shape.

[0157] With the increasing integration of semiconductors, there is a need for finer circuit patterns. Exposure light with shorter wavelengths than existing exposure light can be used to form these fine patterns on semiconductor wafers. Examples of suitable exposure light for forming fine patterns include ArF excimer lasers (wavelength 193 nm).

[0158] The light source that produces short-wavelength exposure light requires high output. This type of light source can increase the temperature of the photomask during the exposure process.

[0159] Thin films included in a photomask and patterned therein can exhibit physical properties such as thickness and height that vary with temperature. These thin films are not formed from the same material and can have a multilayer structure with at least two layers. Furthermore, due to processes such as oxidation and heat treatment, differences sometimes arise between the characteristics of the initially stacked films and those in the completed blank mask. Especially when the variation in thickness, height, etc., of each film cannot be controlled according to temperature, this can contribute to a reduction in the resolution of the pattern formed on the semiconductor wafer.

[0160] Furthermore, in order to develop finer circuit patterns with excellent resolution, it is necessary to more precisely adjust the phase difference and transmittance of the phase shift film, and reduce the thickness of the phase shift film.

[0161] A protective layer can be formed on the surface of a phase-shifting film to improve its durability. Methods for forming a protective layer on the surface of a phase-shifting film include: forming the protective layer through natural oxidation without applying a separate process; forming a separate layer on the surface of the phase-shifting film through sputtering or similar methods; and applying a heat treatment process to the surface of the phase-shifting film.

[0162] When using natural oxidation processes, the in-plane optical properties of the phase-shifting film may be unevenly distributed, potentially leading to insufficient durability. When using processes that form a separate layer on the surface of the phase-shifting film or undergo heat treatment, the overall optical properties of the phase-shifting film may change significantly due to the influence of the protective layer.

[0163] The inventors of the embodiment confirmed through experiments that a blank mask with higher resolution can be provided by means of the following method, and completed the embodiment by adjusting the thermal fluctuation value of the film included in the blank mask according to temperature within a certain range.

[0164] The various embodiments are described in more detail below.

[0165] Figure 1 This is a conceptual diagram illustrating a blank mask according to one embodiment of this specification. Referring to the... Figure 1 Example of implementation.

[0166] A blank mask 100 according to one embodiment of this specification includes: a transparent substrate 10; a phase shift film 20 disposed on the transparent substrate 10; and a light-shielding film 30 disposed on the phase shift film 20.

[0167] The material of the transparent substrate 10 is not limited as long as it is transparent to exposure light and can be used in a photomask. Specifically, the transparent substrate 10 can have a transmittance of 85% or more to exposure light with wavelengths below 200 nm. The transmittance can be 87% or more. For example, a synthetic quartz substrate can be used in the transparent substrate 10. In this case, the transparent substrate 10 can suppress the attenuation of light transmitted through it.

[0168] In addition, the transparent substrate 10 can suppress the occurrence of optical distortion by adjusting surface characteristics such as flatness and roughness.

[0169] The phase shift film 20 can be located on the front side of the transparent substrate 10.

[0170] Thermal fluctuation characteristics of phase-shifting films

[0171] The TFT1 value of the blank mask, expressed by the following formula 1, is less than or equal to 0.25 μm / 100 °C:

[0172] [Formula 1]

[0173]

[0174] When analyzing the thermal fluctuations of the processed blank mask formed by processing the transparent substrate of the blank mask to a thickness of 0.6 mm and removing the light-shielding film in a thermomechanical analyzer, the measured temperature of the thermomechanical analyzer rises from T1 to T2, and ΔPM is the change in position of the upper surface of the phase shift film in the thickness direction at T2, with the upper surface of the phase shift film at T1 as a reference.

[0175] The optical properties of the phase-shift film 20 depend on the composition of the elements contained in the phase-shift film 20, as well as various factors such as the density and thickness of the phase-shift film 20. Therefore, the phase-shift film 20 is designed and formed by taking these factors into account to maximize the resolution of the blank mask 100. The phase-shift film 20 can be exposed to heat generated from the light source during the exposure process. The thickness, stress, etc., of the phase-shift film 20 can change with the heat. In this case, the optical properties of the phase-shift film may exhibit varying values ​​instead of the pre-designed values. In addition, when the phase-shift film 20 is patterned, deformation of the patterned phase-shift film is easily caused, which may become a factor causing a decrease in the resolution of the photomask. The embodiment can effectively suppress the decrease in the resolution of the blank mask by controlling the thermal fluctuations of the phase-shift film, etc.

[0176] The TFT1 value according to Formula 1 can be adjusted by controlling factors such as the types of elements constituting the phase shift film 20, the content of each element, the magnetic field strength applied to the sputtering process, the substrate rotation speed, the voltage applied to the target, the atmospheric gas composition, the sputtering temperature, and the post-processing conditions. Specifically, in this embodiment, the TFT1 value of the phase shift film 20 is controlled by applying a method for adjusting the magnetic field strength applied during the formation of the phase shift film 20.

[0177] During the formation of the phase-shift film 20, a magnetic field can be generated in the sputtering chamber by placing a magnet in the sputtering equipment, causing the plasma to be distributed across the entire surface of the sputtered target. Furthermore, the density of the phase-shift film 20 formed by the sputtering equipment can be adjusted by controlling the magnetic field distribution, magnetic field strength, and other parameters.

[0178] Specifically, a stronger magnetic field results in a higher density of plasma in the chamber, leading to a higher density of the phase-shifting film 20. Conversely, a weaker magnetic field results in a lower density of plasma in the chamber, leading to a lower density of the phase-shifting film 20. Therefore, the TFT1 value can be controlled by adjusting the magnetic field conditions of the sputtering equipment to control the density of the phase-shifting film 20.

[0179] The TFT1 value is measured using a thermomechanical analyzer. Specifically, the tip of the thermomechanical analyzer is placed 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 pre-set heating rate in the embodiment to measure the positional change of the upper surface of the phase shift film in the thickness direction according to the temperature change, i.e., the TFT1 value.

[0180] Unlike simply measuring the thickness of a thin film based on temperature, the stress change of the thin film, the degree of thermal expansion of the thin film, and the degree of curvature of the substrate of the thin film can be comprehensively evaluated by measuring the TFT1 value as described above.

[0181] The TFT1 value was measured under the conditions of a tip load of 0.05 N, a heating rate of 10 °C / min, and a measurement temperature range of 30 to 200 °C.

[0182] In this embodiment, the thickness of the transparent substrate 10 is processed to 0.6 mm when measuring the TFT1 value. This is to facilitate the placement of the blank mask to be measured into the thermomechanical analyzer. Methods for adjusting the thickness of the transparent substrate 10 include, for example, etching the surface opposite to one surface of the transparent substrate 10 where the phase shift film 20 is disposed, or cutting a portion of the other surface side of the phase shift film 20.

[0183] When measuring the TFT1 value, the light-shielding film 30 located on the phase-shifting film 20 is removed before measurement. If other films exist between the phase-shifting film 20 and the light-shielding film 30, these other films are removed. Specifically, the measurement is performed after processing the blank mask 100 to expose the uppermost surface of the phase-shifting film 20. Methods for removing the light-shielding film 30 and the other films include etching, but are not limited to these.

[0184] On the upper surface side of the phase shift film 20, there may be a portion where the phase shift film 20 and another thin film (e.g., a light-shielding film) are mixed on the phase shift film 20 and in contact with it. In this case, the TFT1 value is measured after removing the mixed portion.

[0185] Removing the mixed portion without damaging the phase shift film 20 is technically difficult. Therefore, by removing the mixed portion and the upper part of the phase shift film, the thickness of the processed phase shift film 20 is made to be greater than 50 nm, and then the TFT1 value is measured.

[0186] For example, there is the TA INSTRUMENT Q400 thermomechanical analyzer used to measure TFT1 values.

[0187] When calculating the TFT1 value, ΔPM refers to the absolute value of the positional change in the thickness direction of the upper surface of the phase shift film under T2, with the upper surface of the phase shift film under T1 as the reference. For example, when the dimension change in the thickness direction of the phase shift film is 0.2 μm under T1 and 0.5 μm under T2, ΔPM is 0.3 μm.

[0188] T1 is the initial temperature of the thermomechanical analyzer when measuring the TFT1 value.

[0189] T2 is the temperature of the thermomechanical analyzer after rising from the initial temperature when measuring the TFT1 value.

[0190] When calculating the TFT1 value, the unit is μm / 100℃. For example, with T1 value of 30℃, T2 value of 200℃, and ΔPM value of 0.25 μm, the calculated TFT1 value is 0.25 / (200-30)*100=0.147 μm / 100℃.

[0191] The TFT1 value of the blank mask 100 can be below 0.25µm / 100℃. The TFT1 value can be below 0.2µm / 100℃. The TFT1 value can be below 0.18µm / 100℃. The TFT1 value can be above 0.1µm / 100℃. The TFT1 value can be above 0.12µm / 100℃. The TFT1 value can be above 0.15µm / 100℃.

[0192] When T1 is 30℃ and T2 is 200℃, the TFT1 value of the blank mask 100 can be below 0.25um / 100℃. The TFT1 value can be below 0.2um / 100℃. The TFT1 value can be below 0.18um / 100℃. The TFT1 value can be above 0.1um / 100℃. The TFT1 value can be above 0.12um / 100℃. The TFT1 value can be above 0.15um / 100℃.

[0193] When T1 is 50℃ and T2 is 80℃, the TFT1 value of the blank mask 100 can be below 0.25um / 100℃. The TFT1 value can be below 0.2um / 100℃. The TFT1 value can be below 0.18um / 100℃. The TFT1 value can be above 0.1um / 100℃. The TFT1 value can be above 0.12um / 100℃. The TFT1 value can be above 0.15um / 100℃.

[0194] In this way, the deformation of the phase-shifted patterned film caused by heat generated during the exposure process can be suppressed, thereby improving the resolution of the photomask. In addition, the phase-shifted patterned film can have stable durability.

[0195] When T1 is 50℃ and T2 is 150℃, the TFT1 value of the blank mask 100 can be below 0.25um / 100℃. The TFT1 value can be below 0.2um / 100℃. The TFT1 value can be below 0.18um / 100℃. The TFT1 value can be above 0.1um / 100℃. The TFT1 value can be above 0.12um / 100℃. The TFT1 value can be above 0.15um / 100℃.

[0196] In this case, the photomask can have excellent resolution even at higher temperatures.

[0197] When T1 is 100 to 140°C and T2 = T1 + 5°C, the TFT1 value of the blank mask 100 can be less than 0.1 μm. The TFT1 value can be less than 0.07 μm. The TFT1 value can be less than 0.05 μm. The TFT1 value can be greater than 0.005 μm. The TFT1 value can be greater than 0.01 μm. The TFT1 value can be greater than 0.02 μm. Under these conditions, fluctuations in the optical properties and pattern distortion of the patterned phase-shift film due to rising ambient temperature during the exposure process can be suppressed.

[0198] When T1 is 170 to 180°C and T2 = T1 + 5°C, the TFT1 value of the blank mask 100 can be 0.15 μm or less. The TFT1 value can be 0.12 μm or less. The TFT1 value can be 0.1 μm or less. The TFT1 value can be 0.005 μm or more. The TFT1 value can be 0.01 μm or more. The TFT1 value can be 0.02 μm or more. Under these conditions, the phase-shifting film can exhibit stable durability in a high-temperature atmosphere.

[0199] Thermal fluctuation characteristics of light-shielding film

[0200] The TFT2 value of the blank mask 100, as expressed by the following formula 2, can be below 0.25 μm / 100 °C.

[0201] [Equation 2]

[0202]

[0203] Specifically, when analyzing the thermal fluctuations of the processed blank mask 100 formed by processing the transparent substrate 10 of the blank mask to a thickness of 0.6 mm in a thermomechanical analyzer, the measured temperature of the thermomechanical analyzer rises from T1 to T2, and ΔPC is the change in position of the upper surface of the light-shielding film 30 in the thickness direction at T2, with the upper surface of the light-shielding film 30 at T1 as a reference.

[0204] The patterned light-shielding film 30 is located on the pattern of the phase-shift film 20 and can form a blind pattern. Similar to the pattern of the phase-shift film 20, the pattern of the light-shielding film 30 can also be exposed to heat generated from the high-output light source during the exposure process. As a result, the thickness value, residual stress, and degree of curvature of the substrate including the light-shielding film of the light-shielding film may vary. Similar to the phase-shift film 20, such variations may become a factor leading to a decrease in the resolution of the developed pattern. The embodiment can suppress dimensional changes in the thickness direction of the light-shielding film 30 caused by heat generated from the high-output light source by adjusting the TFT2 value of the blank mask within a predetermined range in the embodiment.

[0205] The TFT2 value of the blank mask 100 may be affected by various factors such as the elements constituting the light-shielding film 30, sputtering process conditions, and film thickness. In particular, this embodiment adjusts the TFT2 value of the blank mask 100 by controlling the magnetic field strength during the sputtering process of the light-shielding film 30. Specifically, the TFT2 value is adjusted by controlling the density of the formed light-shielding film 30 by controlling the magnetic field during the sputtering process.

[0206] The TFT2 value is measured using a thermomechanical analyzer. Specifically, the tip of the thermomechanical analyzer is placed 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 using the tip, and the positional change in the thickness direction of the light-shielding film is measured according to the temperature by heating the surface of the light-shielding film 30 at a pre-set heating rate in the embodiment.

[0207] Unlike simply measuring the thickness of the light-shielding film based on temperature, the stress variation of the light-shielding film, the degree of thermal expansion of the light-shielding film, and the degree of bending of the substrate of the light-shielding film can be comprehensively evaluated by measuring the TFT2 value as described above.

[0208] When measuring the TFT2 value, the measurement conditions applicable to the thermomechanical analyzer are the same as those for measuring the TFT1 value.

[0209] When measuring the TFT2 value, the thickness of the transparent substrate 10 is processed to 0.6 mm. The processing method applicable to the transparent substrate 10 is the same as the processing method used when measuring the TFT1 value.

[0210] When measuring the TFT2 value, if other layers are present on the light-shielding film 30, the measurement is performed after removing the other layers. Methods for removing the other layers include, for example, etching, but are not limited to these.

[0211] Depending on the manufacturing process, there may be a mixture of the light-shielding film 30 and other layers located on the light-shielding film 30. In this case, the TFT2 value is measured after removing the mixed portion.

[0212] It is technically difficult to remove the mixed portion without damaging the light-shielding film. Therefore, by removing the mixed portion and the upper part of the light-shielding film, the thickness of the light-shielding film after processing is made to be more than 40 nm, and then the TFT2 value is measured.

[0213] A thermomechanical analyzer for measuring TFT2 values, for example, the TAINSTRUMENT Q400, can be used.

[0214] When calculating the TFT2 value, ΔPC refers to the absolute value of the positional change of the upper surface of the light-shielding film 30 in the thickness direction under T2, with the upper surface of the light-shielding film 30 under T1 as the reference. For example, if the dimensional change of the light-shielding film in the thickness direction under T1 is 0.2 μm and the dimensional change of the light-shielding film in the thickness direction under T2 is 0.5 μm, then ΔPC is 0.3 μm.

[0215] T1 is the initial temperature of the thermomechanical analyzer when measuring the TFT2 value.

[0216] T2 is the temperature of the thermomechanical analyzer after rising from the initial temperature when measuring the TFT2 value.

[0217] Calculate the TFT2 value using the unit of T2-T1 as μm / 100℃, and continue until the value is reached. For example, with T1 value of 30℃, T2 value of 200℃, and ΔPM value of 0.25 μm, the calculated TFT2 value is 0.25 / (200-30)*100=0.147 μm / 100℃.

[0218] The TFT2 value of the blank mask 100 can be below 0.25 μm / 100°C. The TFT2 value can be below 0.2 μm / 100°C. The TFT2 value can be below 0.1 μm / 100°C. The TFT2 value can be below 0.07 μm / 100°C. The TFT2 value can be above 0.01 μm / 100°C. The TFT2 value can be above 0.03 μm / 100°C. The TFT2 value can be above 0.05 μm / 100°C.

[0219] When T1 is 30℃ and T2 is 200℃, the TFT2 value of the blank mask 100 can be below 0.25um / 100℃. The TFT2 value can be below 0.2um / 100℃. The TFT2 value can be below 0.1um / 100℃. The TFT2 value can be below 0.07um / 100℃. The TFT2 value can be above 0.01um / 100℃. The TFT2 value can be above 0.03um / 100℃. The TFT2 value can be above 0.05um / 100℃.

[0220] When T1 is 50℃ and T2 is 150℃, the TFT2 value of the blank mask 100 can be below 0.8µm / 100℃. The TFT2 value can be below 0.7µm / 100℃. The TFT2 value can be below 0.6µm / 100℃. The TFT2 value can be above 0.2µm / 100℃. The TFT2 value can be above 0.3µm / 100℃. The TFT2 value can be above 0.5µm / 100℃.

[0221] When T1 is 50℃ and T2 is 100℃, the TFT2 value of the blank mask 100 can be below 0.8µm / 100℃. The TFT2 value can be below 0.7µm / 100℃. The TFT2 value can be below 0.6µm / 100℃. The TFT2 value can be above 0.2µm / 100℃. The TFT2 value can be above 0.3µm / 100℃. The TFT2 value can be above 0.5µm / 100℃.

[0222] In this case, it is possible to suppress the changes in the optical properties of the light-shielding film 30 caused by the heat emitted from the high-output light source during the exposure process, thus preventing a decrease in the resolution of the photomask.

[0223] When T1 is between 100°C and 140°C, and T2 = T1 + 5°C, the TFT2 value of the blank mask 100 can be below 0.1µm / 100°C. The TFT2 value can be below 0.07µm / 100°C. The TFT2 value can be below 0.05µm / 100°C. The TFT2 value can be above 0.005µm / 100°C. The TFT2 value can be above 0.01µm / 100°C. The TFT2 value can be above 0.02µm / 100°C. In this case, when the patterned light-shielding film is applied to the photolithography process, shape deformation due to temperature rise can be suppressed.

[0224] When T1 is 170°C to 180°C and T2 = T1 + 5°C, the TFT2 value of the blank mask 100 can be below 0.15 μm / 100°C. The TFT2 value can be below 0.12 μm / 100°C. The TFT2 value can be below 0.1 μm / 100°C. The TFT2 value can be above 0.005 μm / 100°C. The TFT2 value can be above 0.01 μm / 100°C. The TFT2 value can be above 0.02 μm / 100°C. Under these conditions, the patterned light-shielding film can maintain stable optical properties and durability even at high temperatures.

[0225] Layer structure of phase-shifting films

[0226] Figure 2This is a conceptual diagram illustrating a blank mask according to another embodiment of this specification. (Refer to the description...) Figure 2 Example of implementation.

[0227] The phase shift film 20 may include a phase difference adjustment layer 21 and a protective layer 22 disposed on the phase difference adjustment layer 21.

[0228] The phase shift film 20, the phase difference adjustment layer 21, and the protective layer 22 may contain transition metals, silicon, oxygen, and nitrogen.

[0229] The phase difference adjustment layer 21 is a layer in the phase shift film 20 that uniformly contains transition metals, silicon, oxygen, and nitrogen in a depth direction of 5 atomic percent. The phase difference adjustment layer 21 can substantially adjust the phase difference and transmittance of light transmitted through the phase shift film 20.

[0230] Specifically, the phase difference adjustment layer 21 has the property of shifting the phase of exposure light incident from the back side of the transparent substrate 10. Through this property, the phase shift film 20 effectively cancels the diffracted light generated at the edge of the light-transmitting portion in the photomask, thereby further improving the resolution of the photomask during the photolithography process.

[0231] Furthermore, the phase difference adjustment layer 21 attenuates the exposure light incident from the back side of the transparent substrate 10. As a result, the phase shift film 20 can block the transmission of exposure light while canceling the diffraction light generated at the edge of the light-transmitting portion.

[0232] A protective layer 22 is formed on the surface of the phase-shifting film, having a distribution where the oxygen content continuously decreases from the surface to the depth direction, while the nitrogen content continuously increases. The protective layer 22 can suppress damage to the phase-shifting film 20 or the patterned phase-shifting film during photomask etching or cleaning processes, thereby improving the durability of the phase-shifting film 20. Furthermore, the protective layer 22 can prevent the phase difference adjustment layer 21 from being oxidized by exposure light during the exposure process.

[0233] Optical properties of phase-shifting films measured using an ellipsometer

[0234] When PE1 is 1.5 eV and PE2 is 3.0 eV, the photon energy at the point where Del_2 of the blank mask is 0 according to Equation 3 can be between 1.8 eV and 2.14 eV.

[0235] [Formula 3]

[0236]

[0237] In Equation 3, when the light-shielding film is removed from the blank mask and the surface of the phase-shifting film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°.

[0238] The PE value is the photon energy of the incident light within the range of the PE1 value to the PE2 value.

[0239] The resolution of the photomask can be improved by precisely adjusting the optical properties of the phase shift film 20.

[0240] Specifically, the phase difference and transmittance of the phase shift film 20 for the exposed light can be adjusted simultaneously. The phase difference and transmittance of the phase shift film 20 can be controlled by adjusting its composition, thickness, etc. The thickness and transmittance of the phase shift film 20, and the thickness and phase difference of the phase shift film 20, are interrelated. However, there is a trade-off between phase difference and transmittance, which makes it difficult to simultaneously achieve the desired values.

[0241] In this embodiment, a phase shift film 20 for light with wavelengths below 200 nm is provided by controlling the phase difference distribution of the P-wave and S-wave of the phase shift film measured by an ellipsometer. The phase difference and transmittance of the phase shift film are adjusted within a predetermined range in this embodiment, and the film is made thinner.

[0242] Figure 3 This is a conceptual diagram illustrating the principle of measuring the phase difference between the P-wave and S-wave of reflected light from a phase-shifting film using an elliptic polarization spectrometer. (Refer to the above...) Figure 3 Example of implementation.

[0243] The phase difference Δ between the P-wave P' and S-wave S' of the reflected light Lr, at a fixed incident angle θ, may vary depending on the photon energy of the incident light Li in the elliptically polarized spectrometer. This Del_2 value can be calculated by measuring the phase difference Δ between the P-wave P' and S-wave S' of the reflected light Lr at the photon energy of the incident light Li using the phase shift film 20.

[0244] The distribution of Del² values ​​can be adjusted by controlling various factors such as the elements constituting the phase-shifting film 20, sputtering process conditions, film thickness, and the incident angle set in the elliptic polarization spectrometer. In particular, the distribution of Del² values ​​in the phase-shifting film 20 can be controlled by methods such as adjusting the magnetic field strength applied to the formation of the phase-shifting film 20.

[0245] The Del_2 value is measured using an elliptic polarization spectrometer. For example, the phase difference Δ between the P-wave P` and S-wave S` of the reflected light Lr from the phase-shifting film can be measured using a NANO-VIEW MG-PRO model.

[0246] When measuring the Del_2 value distribution of the phase shift film 20, the light-shielding film 30 located on the phase shift film 20 is removed before measurement. If other thin films exist between the phase shift film 20 and the light-shielding film 30, these other thin films are removed. Etching is one method for removing the light-shielding film 30 and the other films, but it is not limited to this method. Since it is technically difficult to remove other films located on the phase shift film without damaging the phase shift film 20, damage of less than 1 nm in the thickness direction to the phase shift film is permitted during the etching process.

[0247] In the blank mask 100, when PE1 is 1.5 eV and PE2 is 3.0 eV, the photon energy at the point where Del_2 is 0 can be between 1.8 eV and 2.14 eV. The photon energy can be between 1.85 eV and 2.1 eV. The photon energy can be between 1.9 eV and 2.05 eV. In this case, the phase-shifting film 20 can have the desired transmittance and phase difference for short-wavelength exposure light, with a smaller thickness.

[0248] In the blank mask 100, when PE1 is 3eV and PE2 is 5eV, the photon energy at the point where Del_2 is 0 can be 3.8 to 4.64eV.

[0249] When high-energy incident light Li is irradiated onto the object being measured, the incident light Li is reflected at the surface of the phase-shifting film 20 or at a shallow depth in the depth direction due to its short wavelength. By analyzing the phase difference between the P-wave and S-wave of the reflected light formed by irradiating the surface of the phase-shifting film 20 with incident light Li configured to have high photon energy, the optical properties of the surface portion of the phase-shifting film 20, especially the optical properties of the protective layer 22, can be confirmed.

[0250] The protective layer 22 is located on the phase difference adjustment layer 21 and functions to protect the phase difference adjustment layer 21 from exposure light and cleaning solutions. The thicker the protective layer 22, the denser its structure, and the more stably it can protect the phase difference adjustment layer 21. However, if the protective layer 22 is formed solely with consideration for the stable protection of the phase difference adjustment layer 21, the overall optical properties of the phase shift film 20 may change significantly due to the formation of the protective layer 22. In this case, the phase shift film 20 may have optical properties deviating from the originally designed optical properties. The embodiment provides a phase shift film 20 in which the phase difference adjustment layer 21 is stably protected, while the optical properties do not change significantly compared to before the formation of the protective layer 22, by controlling the P-wave and S-wave distribution characteristics of the phase shift film 20.

[0251] The photon energy distribution at the point where Del_2 is 0 when PE1 is 3 eV and PE2 is 5 eV can be adjusted by controlling factors such as the atmospheric gas composition, annealing temperature, and heating rate during the annealing process of the phase difference adjustment layer 21. In particular, the Del_2 value can be controlled by adjusting the heat treatment temperature and time during the annealing process after UV light treatment of the surface of the formed phase difference adjustment layer 21.

[0252] In the blank mask 100, when PE1 is 3 eV and PE2 is 5 eV, the photon energy at the point where Del_2 is 0 can be 3.8 eV to 4.64 eV. The photon energy can be 4 eV to 4.62 eV. The photon energy can be 4.2 eV to 4.6 eV. The photon energy can be 4.3 eV to 4.5 eV. In this case, the protective layer 22 can fully protect the phase difference adjustment layer 21 while controlling the changes in the optical properties of the phase shift film 20 caused by the formation of the protective layer 22 within a certain range.

[0253] In the blank mask 100, when the PE1 value is 1.5 eV and the PE2 value is the minimum of the photon energies of the incident light at the point where the Del_2 value is 0, the average value of Del_2 can be from 78° / eV to 98° / eV.

[0254] When the incident light has a photon energy of 1.5 eV or higher and a Del_2 value of 0, but is within the range below the minimum value of the incident light photon energy, the incident light has a relatively long wavelength. This incident light is reflected after passing through relatively deep inside the phase shift film. Therefore, the average value of Del_2 measured after setting the photon energy within the range described above reflects the optical properties of the phase difference adjustment layer 21 in the phase shift film 20.

[0255] In the blank mask 100, when PE1 is 1.5 eV and PE2 is the minimum photon energy of the incident light at the point where Del_2 is 0, the average value of Del_2 can be 78 to 98° / eV. The average value can be 80 to 95° / eV. The average value can be 82 to 93° / eV. In this case, the phase difference adjustment layer 21 helps the phase shift film 20 to have a lower thickness while maintaining the target phase difference and transmittance for short-wavelength light.

[0256] In the blank mask 100, when PE1 is the minimum photon energy of the incident light at the point where Del_2 is 0, and PE2 is the maximum photon energy of the incident light at the point where Del_2 is 0, the average value of Del_2 can be -65 to -55° / eV.

[0257] When the photon energy of the incident light is within a range that is above the minimum photon energy of the incident light at the point where the Del_2 value is 0 and below the maximum photon energy of the incident light at the point where the Del_2 value is 0, the average value of the Del_2 value measured under these conditions reflects the optical properties of the portion near the interface between the phase difference adjustment layer 21 and the protective layer 22.

[0258] In the blank mask 100, when PE1 is the minimum photon energy of the incident light at the point where Del_2 is 0, and PE2 is the maximum photon energy of the incident light at the point where Del_2 is 0, the average value of Del_2 can be -65 to -55° / eV. The average value can be -62 to -56° / eV. The average value can be -59 to -57° / eV. In this case, it is possible to suppress the large influence of the interface formed between the phase difference adjustment layer 21 and the protective film 22 on the optical properties of the entire phase shift film.

[0259] In the blank mask 100, when PE1 is the maximum value of the photon energy of the incident light at the point where the value of Del_2 is 0, and PE2 is 5.0 eV, the average value of Del_2 can be 60 to 120° / eV.

[0260] The average value of Del_2, measured by setting PE1 to the maximum value of the photon energy of the incident light at the point where Del_2 is 0 and PE2 to 5.0 eV, reflects the optical properties of the protective layer 22, etc.

[0261] In the blank mask 100, when PE1 is the maximum photon energy of the incident light at the point where Del_2 is 0, and PE2 is 5.0 eV, the average value of Del_2 can be from 60° / eV to 120° / eV. The average value can be from 70 to 110° / eV. The average value can be from 80 to 105° / eV. In this case, the influence of the protective layer 22 on the overall optical properties of the phase-shifting film 20 can be reduced, and the phase-shifting film 20 can have stable durability.

[0262] In the blank mask 100, when the PE1 value is 1.5 eV and the PE2 value is 3.0 eV after the protective layer 22 is formed, the absolute value of the difference between the photon energy value of the incident light at the point where the Del_2 value is 0 and the photon energy value of the incident light at the point where the Del_2 value is 0 is measured before the protective layer 22 is formed can be 0.001 to 0.2 eV.

[0263] 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 may change. Specifically, when the phase difference adjustment layer is annealed under controlled atmosphere pressure and temperature conditions, the residual stress in the phase difference adjustment layer and the composition of the phase difference adjustment layer surface may change. This change may lead to changes in the optical properties of the phase difference adjustment layer itself. This may be the reason why the phase shift film has characteristics that deviate from the intended optical properties in the embodiment. The embodiment can provide a blank mask that can present 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.

[0264] In the blank mask 100, when the PE1 value is 1.5 eV and the PE2 value is 3.0 eV after the formation of the protective layer 22, the absolute value of the difference between the photon energy value of the incident light at the point where the Del_2 value is 0 and the photon energy value of the incident light at the point where the Del_2 value is 0 measured before the formation of the protective layer 22 can be 0.001 to 0.2 eV. The absolute value can be 0.005 to 0.1 eV. The absolute value can be 0.01 to 0.008 eV. In this case, the blank mask 100 can suppress the optical variations of the phase difference adjustment layer 21 itself caused by the formation of the protective layer 22.

[0265] In the blank mask 100, when the PE1 value is 3.0 eV and the PE2 value is 5.0 eV after the protective layer 22 is formed, the absolute value of the difference between the photon energy value of the incident light at the point where the Del_2 value is 0 and the photon energy value of the incident light at the point where the Del_2 value is 0 is measured before the formation of the protective layer 22 can be 0.05 to 0.3 eV. The absolute value can be 0.06 to 0.25 eV. The absolute value can be 0.1 to 0.23 eV. In this case, the blank mask 100 can reduce the influence of the optical properties of the protective layer 22 itself on the optical properties of the entire phase-shifting film 20.

[0266] In the blank mask 100, when PE1 is 1.5 eV and PE2 is 5.0 eV, the maximum value of Del_2 can be from 105° / eV to 300° / eV.

[0267] In the embodiment, the phase shift film 20 can have stable durability by adjusting the maximum value of Del_2 when the PE1 value of the blank mask 100 is 1.5 eV and the PE2 value is 5.0 eV, while adjusting the changes in the optical properties of the entire phase shift film 20 caused by the formation of the protective layer 22 within a certain range.

[0268] In the blank mask 100, when PE1 is 1.5 eV and PE2 is 5.0 eV, the maximum value of Del_2 can be 105 to 300 eV. This maximum value is 120 to 200 eV. This maximum value can be 140 to 160 eV. In this case, the variation in the optical properties of the entire phase-shifting film 20 caused by the formation of the protective layer 22 can be reduced, while the phase-shifting film 20 can exhibit excellent lightfastness and chemical resistance.

[0269] In the blank mask 100, when PE1 is 1.5 eV and PE2 is 5.0 eV, the photon energy at the point where Del_2 is the maximum value can be above 4.5 eV.

[0270] When PE1 is 1.5 eV and PE2 is 5.0 eV, the maximum value of Del_2 reflects the optical properties of the protective layer 22. The embodiment can achieve stable durability of the protective layer 22 by adjusting the photon energy value at the point where Del_2 is at its maximum value, while simultaneously reducing the impact of the protective layer 22 on the overall optical properties of the phase-shifting film 20.

[0271] In the blank mask 100, when PE1 is 1.5 eV and PE2 is 5.0 eV, the photon energy at the point where Del_2 is at its maximum value can be 4.5 eV or higher. The photon energy at the point where Del_2 is at its maximum value can be 4.55 eV or higher. The photon energy at the point where Del_2 is at its maximum value can be 5 eV or lower. The photon energy at the point where Del_2 is at its maximum value can be 4.8 eV or lower. In this case, the phase shift film 20 can exhibit the desired optical properties for short wavelengths while suppressing variations in optical properties caused by exposure and cleaning processes.

[0272] In the blank mask 100, when the value of PE1 is 1.5 eV and the value of PE2 is 5.0 eV, the value of subtracting the minimum value of Del_2 from the maximum value of Del_2 can be between 60 and 260 eV.

[0273] The inventors of the embodiment discovered through experiments that when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of Del_2 reflects the optical characteristics of the protective layer 22 of the phase shift film 20, and the minimum value of Del_2 reflects the optical characteristics of the upper part of the phase difference adjustment layer 21.

[0274] Before and after the formation of the protective layer, when PE1 is 1.5 eV and PE2 is 5.0 eV, the maximum and minimum values ​​of Del_2 may change. As long as the difference between the maximum and minimum values ​​of Del_2 is kept within a certain range, the optical properties of the entire phase-shifting film 20 can change within an acceptable range before and after the formation of the protective layer 22.

[0275] In a blank mask, when PE1 is 1.5 eV and PE2 is 5.0 eV, the difference between the maximum and minimum values ​​of Del_2 can be 60 to 260 eV. The difference between the maximum and minimum values ​​of Del_2 can be 80 to 240 eV. The difference between the maximum and minimum values ​​of Del_2 can be 90 to 230 eV. In this case, the variation in the optical properties of the entire phase-shifting film before and after the formation of the protective layer can be controlled within a certain range.

[0276] Composition of phase-shifting films

[0277] The phase-shifting film 20 may contain a transition metal, silicon, oxygen, and nitrogen. The transition metal may be one or more elements selected from, but not limited to, molybdenum (Mo), tantalum (Ta), zirconium (Zr), etc. For example, the transition metal may be molybdenum.

[0278] Phase-shifting film 20 may contain 1 to 10 atomic percent of transition metal. Phase-shifting film 20 may contain 2 to 7 atomic percent of transition metal. Phase-shifting film 20 may contain 15 to 60 atomic percent of silicon. Phase-shifting film 20 may contain 25 to 50 atomic percent of silicon. Phase-shifting film 20 may contain 30 to 60 atomic percent of nitrogen. Phase-shifting film 20 may contain 35 to 55 atomic percent of nitrogen. Phase-shifting film 20 may contain 5 to 35 atomic percent of oxygen. Phase-shifting film 20 may contain 10 to 25 atomic percent of oxygen. In this case, phase-shifting film 20 may have optical properties suitable for photolithography processes using short-wavelength exposure light, specifically, light with wavelengths below 200 nm.

[0279] The phase-shifting membrane 20 may also contain other elements besides those already mentioned. For example, the phase-shifting membrane 20 may contain argon (Ar), helium (He), etc.

[0280] In the phase-shifting film 20, the content of each element can be different in the thickness direction.

[0281] The elemental distribution in the thickness direction of the phase shift layer 21 and the protective layer 22 can be confirmed by measuring the depth profile of the phase shift film 20. The depth profile of the phase shift film 20 can be measured, for example, using a Thermo Scientific K-alpha model.

[0282] The contents of transition metals, silicon, oxygen, and nitrogen in the phase difference adjustment layer 21 and the protective layer 22 can be different from each other.

[0283] Phase difference adjustment layer 21 may contain 3 to 10 atomic percent of transition metal. Phase difference adjustment layer 21 may contain 4 to 8 atomic percent of transition metal. Phase difference adjustment layer 21 may contain 20 to 50 atomic percent of silicon. Phase difference adjustment layer 21 may contain 30 to 40 atomic percent of silicon. Phase difference adjustment layer 21 may contain 2 to 10 atomic percent of oxygen. Phase difference adjustment layer 21 may contain 3 to 8 atomic percent of oxygen. Phase difference adjustment layer 21 may contain 40 to 60 atomic percent of nitrogen. Phase difference adjustment layer 21 may contain 45 to 55 atomic percent of nitrogen. In this case, when short-wavelength exposure light is applied, specifically, light with a wavelength below 200 nm is used as the exposure light, the blank mask can have excellent pattern resolution.

[0284] The more oxygen contained in the protective layer 22, the more stably the phase shift adjustment layer 21 can be protected from exposure light and cleaning solutions. However, this protective layer 22 may have a greater impact on changes in the optical properties of the entire phase shift film 20 before and after the formation of the protective layer 22. Therefore, the phase shift film 20 can have sufficient lightfastness and chemical resistance, while also possessing the optical properties desired in the embodiments, by controlling the oxygen and nitrogen content distribution in the protective layer 22.

[0285] The protective layer 22 may contain 20 to 40 atomic percent nitrogen. The protective layer 22 may contain 25 to 35 atomic percent nitrogen. The protective layer 22 may contain 10 to 50 atomic percent oxygen. The protective layer 22 may contain 20 to 40 atomic percent oxygen. The protective layer 22 may contain 10 to 50 atomic percent silicon. The protective layer 22 may contain 20 to 40 atomic percent silicon. The protective layer 22 may contain 0.5 to 5 atomic percent transition metal. The protective layer 22 may contain 1 to 3 atomic percent transition metal. In this case, the protective layer 22 can sufficiently suppress the deterioration of the phase difference adjustment layer 21.

[0286] The protective layer 22 may include a region in the thickness direction where the ratio of nitrogen content (atomic %) to oxygen content (atomic %) is 1 or more. The thickness of the region may be 40 to 60% of the total thickness of the protective layer 22. Alternatively, the thickness of the region may be 45 to 55% of the total thickness of the protective layer 22. In this case, the variation in the optical properties of the phase-shifting film 20 caused by the formation of the protective layer 22 can be effectively suppressed.

[0287] The protective layer 22 may include a region in the thickness direction where the ratio of nitrogen content (atomic %) to oxygen content (atomic %) is 0.4 to 2, and the thickness of the region may be 30 to 80% of the total thickness of the protective layer 22. Alternatively, the thickness of the region may be 40 to 60% of the total thickness of the protective layer 22. In this case, a blank mask capable of fabricating a photomask with sufficient durability and excellent resolution can be provided.

[0288] The thickness of the region in which the ratio of nitrogen content (atomic %) to oxygen content (atomic %) in the thickness direction is adjusted can be measured by measuring the depth distribution. However, it is assumed that when measuring the thickness of the region, the etching rate at each depth of the protective layer 22 is constant in the depth distribution.

[0289] Optical properties of phase-shifting films and the thickness of each layer

[0290] The phase shift film 20 can have a phase difference of 160 to 200° for light with wavelengths below 200 nm. The phase shift film 20 can have a phase difference of 160 to 200° for ArF light. The phase shift film 20 can have a phase difference of 170 to 190° for light with wavelengths below 200 nm. The phase shift film 20 can have a phase difference of 170 to 190° for ArF light. The transmittance of the phase shift film 20 for light with wavelengths below 200 nm can be 3 to 10%. The transmittance of the phase shift film 20 for ArF light can be 3 to 10%. The transmittance of the phase shift film 20 for light with wavelengths below 200 nm can be 4 to 8%. The transmittance of the phase shift film 20 for ArF light can be 4 to 8%. In this case, the photomask including the phase shift film 20 can form finer micropatterns on the wafer during an exposure process using short-wavelength exposure light.

[0291] The refractive index of the protective layer 22 for light with wavelengths below 200 nm can be 1.3 to 2. The refractive index of the protective layer 22 for ArF light can be 1.3 to 2. The refractive index of the protective layer 22 for light with wavelengths below 200 nm can be 1.4 to 1.8. The refractive index of the protective layer 22 for ArF light can be 1.4 to 1.8. The extinction coefficient of the protective layer 22 for light with wavelengths below 200 nm can be 0.2 to 0.4. The 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 wavelengths below 200 nm 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 this case, the variation in the optical properties of the phase-shifting film 20 caused by the formation of the protective layer 22 can be minimized.

[0292] The phase difference adjustment layer 21 has a refractive index of 2 to 4 for light with wavelengths below 200 nm. The phase difference adjustment layer 21 has a refractive index of 2 to 4 for ArF light. The phase difference adjustment layer 21 has a refractive index of 2.5 to 3.5 for light with wavelengths below 200 nm. The phase difference adjustment layer 21 has a refractive index of 2.5 to 3.5 for ArF light. The phase difference adjustment layer 21 has an extinction coefficient of 0.3 to 0.7 for light with wavelengths below 200 nm. The phase difference adjustment layer 21 has an extinction coefficient of 0.3 to 0.7 for ArF light. The phase difference adjustment layer 21 has an extinction coefficient of 0.4 to 0.6 for light with wavelengths below 200 nm. The phase difference adjustment layer 21 has an extinction coefficient of 0.4 to 0.6 for ArF light. In this case, the resolution of the photomask including the phase shift film 20 can be further improved.

[0293] The optical properties of the phase-shifting film 20, the protective layer 22, and the phase difference adjustment layer 21 can be measured using an elliptic polarization spectrometer. For example, these optical properties can be measured using a Nanoview MG-PRO device.

[0294] The ratio of the thickness of the protective layer 22 to the thickness of the entire phase shift film 20 can be from 0.04 to 0.09. The thickness ratio can be from 0.05 to 0.08. In this case, the protective layer 22 can stably protect the phase difference adjustment layer 21.

[0295] The thickness of the protective layer 22 can be The above and The thickness of the protective layer 22 can be as follows. The above and The following describes a phase shift film 20 that effectively reduces the variation in the optical properties of the entire phase shift film while maintaining stable optical properties during long exposure and cleaning processes.

[0296] The thickness of the phase-shifting film 20 and the layers constituting the phase-shifting film 20 can be measured using transmission electron microscopy (TEM) images of the cross-section of the phase-shifting film 20.

[0297] Layer structure, composition and optical properties of light-shielding film

[0298] A light-shielding film 30 can be disposed on the phase-shifting film 20. When etching the phase-shifting film 20 according to a pre-designed pattern shape, the light-shielding film 30 can be used as an etching mask for the phase-shifting film 20. In addition, the light-shielding film 30 can block exposure light incident from the back side of the transparent substrate 10.

[0299] The light-shielding film 30 can have a single-layer structure. The light-shielding film 30 can also have a multi-layer structure with two or more layers. In the sputtering process of the light-shielding film 30, the composition and flow rate of the atmospheric gas in each layer of the light-shielding film can be different, thereby forming a multi-layered light-shielding film 30. In the sputtering process of the light-shielding film 30, a multi-layered light-shielding film 30 can be formed by applying different sputtering targets to each layer of the light-shielding film.

[0300] The light-shielding film 30 may contain chromium, oxygen, nitrogen, and carbon. The content of each element in the light-shielding film 30 may vary along the thickness direction of the light-shielding film 30. In the case of a multi-layered light-shielding film, the composition of each layer in the light-shielding film 30 may differ.

[0301] The light-shielding film 30 may contain 30 to 70 atomic percent chromium. The light-shielding film 30 may contain 47 to 57 atomic percent chromium. The light-shielding film 30 may contain 5 to 30 atomic percent carbon. The light-shielding film 30 may contain 7 to 25 atomic percent carbon. The light-shielding film 30 may contain 3 to 30 atomic percent nitrogen. The light-shielding film 30 may contain 5 to 25 atomic percent nitrogen. The light-shielding film 30 may contain 20 to 55 atomic percent oxygen. The light-shielding film 30 may contain 25 to 40 atomic percent oxygen. In this case, the light-shielding film 30 can have sufficient light-absorbing properties.

[0302] The multilayer film (not shown) includes a phase-shifting film 20 and a light-shielding film 30. The multilayer film forms a blind pattern on the transparent substrate 10, thereby suppressing the transmission of exposure light.

[0303] The optical density of the multilayer film for light with wavelengths below 200 nm can be greater than 3. The optical density of the multilayer film for ArF light can be greater than 3. The optical density of the multilayer film for light with wavelengths below 200 nm can be greater than 3.5. The optical density of the multilayer film for ArF light can be greater than 3.5. In these cases, the multilayer film can exhibit excellent light-blocking properties.

[0304] Phase-shifting film preparation method

[0305] The phase difference adjustment layer 21 in the phase shift film 20 of the embodiment can be prepared on the transparent substrate 10 by sputtering.

[0306] In sputtering processes, either a direct current (DC) power supply or a radio frequency (RF) power supply can be used.

[0307] The target and sputtering gas can be selected by considering the composition of the materials that make up the phase-shifting film.

[0308] In the case of sputtering targets, a target containing a transition metal and silicon can be used, or a target containing a transition metal and a target containing silicon can be used separately. When using a single target as a sputtering target, the transition metal content can be 30% or less relative to the total transition metal and silicon content of the target. Alternatively, the content can be 20% or less, 10% or less, or 2% or more. The application of such a target facilitates the formation of a phase-shifted film with desired optical properties during the sputtering process.

[0309] In the case of sputtering gas, CH4 (a carbon-containing gas), O2 (an oxygen-containing gas), N2 (a nitrogen-containing gas), etc., can be introduced, but are not limited to these. Inert gases can be added to the sputtering gas. Examples of inert gases include Ar and He, but are not limited to these. The quality of the formed film can be adjusted according to the type and content of the inert gas. The optical properties of the phase-shifting film can be adjusted by controlling the composition of the inert gas. Various gases can be introduced separately into each chamber as sputtering gases. Alternatively, various gases can be mixed and then the mixed gas introduced into the chamber as the sputtering gas.

[0310] To improve the uniformity of the in-plane thickness and optical properties of the formed phase-shifted film, a magnet can be placed in the chamber. Specifically, the plasma can be more uniformly distributed across the entire surface of the target by placing the magnet on the back side of the sputtering target and rotating it at a speed predetermined in the embodiment. The magnet can rotate at a speed of 50 to 200 rpm.

[0311] The rotational speed of the magnet can be kept constant during sputtering. Alternatively, the rotational speed can be varied during sputtering. During sputtering, the magnet's rotational speed can be increased from an initial speed to a constant speed.

[0312] During sputtering, the magnet's rotational speed can be increased from the initial speed by 5 to 20 rpm. Alternatively, the magnet's rotational speed can be increased from the initial speed by 7 to 15 rpm. In this case, the density distribution of the phase-shifted film in the in-plane direction can be more easily controlled.

[0313] The density of the plasma formed in the sputtering chamber can be adjusted by controlling the magnetic field of the magnet. This allows control over the density of the formed phase-shift film, as well as the TFT1 value of the blank mask and the optical properties of the formed phase-shift film. The magnetic field of the magnet used in the film-forming process of the phase-shift film can be 25 to 60 mT. Alternatively, the magnetic field can be 30 to 50 mT. In this case, thermal fluctuations along the thickness direction of the formed phase-shift film 20 can be suppressed during photolithography processes using short-wavelength exposure light, resulting in a thinner phase-shift film.

[0314] In the sputtering process, the distance between the target and the substrate, i.e., the T / S distance, 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 and the target can be 20 to 30 degrees. Under these conditions, the film formation rate of the phase-shifted film can be stably adjusted, and excessive increase in the internal stress of the phase-shifted film can be suppressed.

[0315] In the sputtering process, the rotational speed of the substrate having the surface to be coated can be adjusted. The rotational speed of the substrate can be from 2 to 20 RPM. The rotational speed can be from 5 to 15 RPM. When the rotational speed of the substrate having the surface to be coated is adjusted within this range, the uniformity of the optical properties in the in-plane direction of the phase-shift film is further improved, while stable durability can be achieved.

[0316] A discharge region comprising a plasma atmosphere can be formed in the sputtering chamber by supplying power to the target material located in the sputtering chamber. The quality of the film formed during sputtering can be adjusted by controlling the magnetic field strength, the rotational speed of the magnet, and simultaneously adjusting the power intensity. The power intensity applied to the sputtering target can be 1 to 3 kW. The power intensity can be 1.5 to 2.5 kW. The power intensity can be 1.8 to 2.2 kW. In this case, the thermal fluctuations of the phase-shifted film in the thickness direction due to thermal changes can be adjusted within a certain range.

[0317] An ellipsometric spectrometer can be installed in the sputtering equipment. This allows for control of the deposition time while monitoring the optical properties of the formed phase shift adjustment layer. Specifically, the Del_2 value of the formed phase shift adjustment layer can be monitored in real time during the deposition process after setting the angle between the incident light and the surface of the formed phase shift adjustment layer. The sputtering process is continued until the Del_2 value falls within a pre-set range in the embodiment, thereby enabling the phase shift film to possess the desired optical properties.

[0318] After the sputtering process is completed, ultraviolet (UV) light can be irradiated onto the surface of the phase détente layer. During the sputtering process, the Si in the silicon dioxide (SiO2) matrix constituting the transparent substrate 10 can be replaced by a transition metal, and oxygen (O) can be replaced by nitrogen (N). If the sputtering process continues, due to exceeding the solubility limit, the transition metal may reside at interstitial sites instead of replacing Si in the SiO2 matrix. In this case, the transition metal can form a mixture with elements such as Si, O, and N on the surface of the formed film. This mixture can be in a homogeneous or inhomogeneous state. If an inhomogeneous mixture forms on the surface of the phase détente layer, short-wavelength exposure light during the exposure process may cause hazy defects on the surface of the phase détente layer. Even when sulfuric acid is used as a cleaning solution to clean the phase-shift film to remove these hazy defects, sulfur ions may remain on the surface of the phase détente layer after cleaning. The sulfur ions may continuously receive strong energy from the exposure light during the wafer exposure process. These high-energy sulfur ions may react with the heterogeneous mixture to generate growth defects on the surface of the phase détente layer. In this embodiment, by irradiating the surface of the phase détente layer with UV light of a controlled wavelength, the content of transition metals and nitrogen in the mixture on the surface of the phase détente layer is homogenized along the in-plane direction, thereby further improving the lightfastness and chemical resistance of the phase détente layer.

[0319] By utilizing 2 to 10 mW / cm 2 A high-power light source irradiates the surface of the phase difference adjustment layer with light of wavelength below 200nm for 5 to 20 minutes to perform surface treatment on the phase difference adjustment layer.

[0320] The phase difference adjustment layer 21 can be heat-treated together with the UV light irradiation process or separately. The UV light irradiation process and heat treatment can be carried out by the heat generated during UV irradiation or separately.

[0321] The phase détente layer 21 formed by sputtering can have internal stress. Depending on the sputtering conditions, the internal stress can be compressive or tensile stress. The internal stress of the phase détente layer may cause the substrate to bend, which may ultimately lead to a decrease in the resolution of the photomask using the phase détente layer. In this embodiment, the phase détente layer is heat-treated to reduce substrate bending.

[0322] The protective layer can be formed after the phase difference adjustment layer is formed by a heat treatment process. The protective layer can be formed on the surface of the phase difference adjustment layer 21 by introducing an atmospheric gas into the chamber during the heat treatment process. Alternatively, the protective layer can be formed by reacting the surface of the phase difference adjustment layer with the atmospheric gas during the heat treatment process. However, the method for preparing the protective layer is not limited to these methods.

[0323] The heat treatment process may include a heating step, a temperature holding step, a cooling step, and a protective layer formation step. The heat treatment process can be performed by placing a blank mask with a phase difference adjustment layer formed on its surface in a chamber and then heating it with a lamp.

[0324] During the heating step, the temperature of the atmosphere in the heat treatment chamber can be raised to a set temperature of 150 to 500°C.

[0325] During the temperature maintenance step, the ambient temperature in the chamber can be maintained at the set temperature, and the pressure in the chamber can be adjusted to 0.1 to 2.0 Pa. The temperature maintenance step can be performed for 5 to 60 minutes.

[0326] During the cooling step, the temperature in the chamber can be reduced from a set temperature to room temperature.

[0327] The protective layer formation step is a step that forms a protective layer on the surface of the phase-shift film by introducing an atmosphere containing a reactive gas into the chamber after the cooling step. The reactive gas may contain oxygen (O2). The gas introduced into the chamber during the protective layer formation step may contain any one selected from nitrogen (N2), argon (Ar), and helium (He). Specifically, during the protective layer formation step, 0.3 to 2.5 standard liters per minute (SLM) of O2 gas may be introduced into the chamber. Alternatively, 0.5 to 2 SLMs of O2 gas may be introduced. The protective layer formation step may be performed for 10 to 60 minutes. Or, it may be performed for 12 to 45 minutes. In this case, the content of each element in the thickness direction of the protective layer is adjusted, thereby suppressing changes in the optical properties of the entire phase-shift film caused by the formation of the protective layer.

[0328] Method for preparing light-shielding film

[0329] The light-shielding film of the embodiment can be formed in contact with the phase-shifting film, or in contact with other thin films located on the phase-shifting film.

[0330] The light-shielding film may include a lower layer and an upper layer located on the lower layer.

[0331] In sputtering processes, either DC or RF power can be used.

[0332] When sputtering a light-shielding film, the sputtering target and sputtering gas can be selected by considering the composition of the light-shielding film to be formed. When the light-shielding film comprises two or more layers, sputtering gases with different compositions can be applied to each layer included in the light-shielding film. Furthermore, when the light-shielding film comprises two or more layers, the compositions of the sputtering target and sputtering gas applied to each layer can be different.

[0333] A single chromium-containing target can be used as a sputtering target, or two or more targets can be used simultaneously. A chromium-containing target can contain more than 90 atomic percent chromium. A chromium-containing target can contain more than 95 atomic percent chromium. A chromium-containing target can contain more than 99 atomic percent chromium.

[0334] In the case of sputtering gas, the composition of the sputtering gas can be adjusted by considering the elemental composition of each layer constituting the light-shielding film, the density of the light-shielding film, and its optical properties.

[0335] The sputtering gas can contain reactive and inert gases. The optical properties and density of the resulting light-shielding film can be controlled by adjusting the content of reactive and inert gases in the sputtering gas. Reactive gases can include CO2, O2, N2, and NO2, etc. Reactive gases can also include other gases besides those listed. Inert gases can include Ar, He, and Ne, etc. Inert gases can also include other gases besides those listed.

[0336] When forming the lower layer of the light-shielding film, a sputtering gas containing Ar, N2, He, and CO2 can be injected into the chamber. Specifically, a sputtering gas in which the sum of the flow rates of CO2 and N2 is more than 40% of the total flow rate of the sputtering gas can be injected into the chamber. In this case, the lower layer of the light-shielding film can have the desired optical properties and can help the light-shielding film to have the desired TFT2 value.

[0337] When forming the upper layer of the light-shielding film, a sputtering gas containing Ar and N2 can be injected into the chamber. Specifically, a sputtering gas with an N2 flow rate of 30% or more relative to the total flow rate of the sputtering gas can be injected into the chamber. In this case, it is possible to help control the dimensional changes of the light-shielding film in the thickness direction as a function of temperature.

[0338] Various gases in the sputtering gas mixture can be injected into the sputtering chamber after mixing. The various gases contained in the sputtering gas can be injected separately through different inlets in the sputtering chamber.

[0339] A magnet can be placed in the chamber to control the density and uniformity of the in-plane optical properties of the light-shielding film to be formed. The method of placing the magnet is the same as that for phase-shifting films, so it is omitted here. The rotation speed of the magnet can be from 50 to 200 rpm.

[0340] In the sputtering process, the distance between the target and the substrate (T / S distance) and the angle between the substrate and the target can be adjusted simultaneously. The T / S distance during the formation of each layer of the light-shielding film can be 240 to 300 mm. The angle between the substrate and the target can be 20 to 30 degrees. Under these conditions, the film deposition rate can be stably adjusted, suppressing excessive rise in internal stress of the formed film.

[0341] In the sputtering process, the rotation speed of the substrate having the surface to be film-formed can be adjusted. When forming the individual layers of the light-shielding film, the rotation speed of the substrate having the surface to be film-formed can be 2 to 50 RPM. The rotation speed of the substrate can be 10 to 40 RPM. In this case, the individual layers of the formed light-shielding film can further improve the optical properties in the in-plane direction and the uniformity of the TFT2 value.

[0342] When the light-shielding film 30 is formed, the intensity of the power applied to the sputtering target can be adjusted. A discharge region including a plasma atmosphere can be formed in the sputtering chamber by supplying power to the target located in the sputtering chamber. The density of the light-shielding film to be formed can be adjusted by controlling the intensity of the magnetic field and the rotation speed of the magnet while adjusting the intensity of the sputtering power.

[0343] When forming the lower layer of the light-shielding film, the power intensity applied to the sputtering target can be 0.5 to 2 kW. The power intensity can be 1.0 to 1.8 kW. The power intensity can be 1.2 to 1.5 kW. When forming the upper layer of the light-shielding film, the power intensity applied to the sputtering target can be 1 to 3 kW. The power intensity can be 1.3 to 2.5 kW. The power intensity can be 1.5 to 2.0 kW. In this case, excessive dimensional changes in the thickness direction of the light-shielding film due to temperature variations can be suppressed.

[0344] An ellipsometer can be installed in the sputtering equipment. This allows for monitoring the optical properties of the formed light-shielding film 30 while controlling the film deposition time. The method for measuring the optical properties of the light-shielding film after installing the ellipsometer in the sputtering equipment is the same as previously described and therefore will be omitted.

[0345] When forming the lower layer of the light-shielding film 30, sputtering can be performed until the photon energy at the point where the phase difference between the P-wave and S-wave of the reflected light, as measured by an ellipsometer, is 140° is 1.6 to 2.2 eV. Alternatively, when forming the lower layer of the light-shielding film 30, sputtering can be performed until the photon energy at the point where the phase difference between the P-wave and S-wave of the reflected light, as measured by an ellipsometer, is 1.8 to 2.0 eV.

[0346] When forming the upper layer of the light-shielding film 30, sputtering can be performed until the photon energy at the point where the phase difference between the P-wave and S-wave of the reflected light, as measured by an ellipsometer, is 140° is 1.7 to 3.2 eV. When forming the upper layer of the light-shielding film 30, sputtering can be performed until the photon energy at the point where the phase difference between the P-wave and S-wave of the reflected light, as measured by an ellipsometer, is 140° is 2.5 to 3.0 eV.

[0347] In this case, the resulting light-blocking film can effectively block the exposure light.

[0348] Photomask

[0349] Another embodiment of the photomask (not shown) may include: a transparent substrate; a phase-shifting pattern film disposed on the transparent substrate; and a light-shielding pattern film disposed on the phase-shifting pattern film.

[0350] The TFT3 value of the photomask, as expressed by Equation 4, is below 0.25 μm / 100 °C.

[0351] [Formula 4]

[0352]

[0353] When the thickness of the transparent substrate of the photomask is processed to 0.6 mm and the thermal fluctuation of the processed photomask is formed by removing the light-shielding pattern film, the measurement temperature of the thermomechanical analyzer rises from T1 to T2. The ΔpPM is the change in position of the upper surface of the phase-shifting pattern film in the thickness direction at T2, with the upper surface of the phase-shifting pattern film at T1 as a reference.

[0354] Another embodiment of the photomask (not shown) may include: a transparent substrate; a phase-shifting pattern film disposed on the transparent substrate; and a light-shielding pattern film disposed on the phase-shifting pattern film.

[0355] In the photomask, when PE1 is 3.0 eV and PE2 is 5.0 eV, the photon energy of the incident light at the point where Del_1 is 0, as expressed by Equation 5, is 4.0 to 5.0 eV.

[0356] [Formula 5]

[0357]

[0358] In Equation 5, when the light-blocking pattern film is removed from the photomask and the surface of the phase-shifting pattern film is measured using an elliptic polarization spectrometer with an incident angle of 64.5°, the pDPS value is the phase difference between the P-wave and the S-wave when the phase difference between the P-wave and the S-wave of the reflected light is less than 180°. When the phase difference between the P-wave and the S-wave of the reflected light is greater than 180°, the pDPS value is obtained by subtracting the phase difference between the P-wave and the S-wave from 360°. The PE value is the photon energy of the incident light in the range of PE1 to PE2.

[0359] The photomask can be made from a blank mask as described above. Specifically, the photomask can be manufactured by patterning the phase-shifting film and the light-blocking film of the blank mask.

[0360] The description of the thermal fluctuation characteristics, optical characteristics, etc. of the phase-shift patterned film and the light-shielding patterned film is the same as the description of the thermal fluctuation characteristics and optical characteristics of the phase-shift film and the light-shielding film as described above, and therefore is omitted.

[0361] The specific embodiments are described in more detail below.

[0362] Preparation examples: Formation of phase-shifting films and light-shielding films

[0363] Example 1: A transparent quartz substrate measuring 6 inches long, 6 inches wide, and 0.25 inches thick is placed in the chamber of a DC sputtering apparatus. A target containing molybdenum and silicon in an atomic ratio of 1:9 is placed in the chamber, such that the T / S distance is 255 mm and the angle between the substrate and the target is 25 degrees. A magnet with a magnetic field of 40 mT is placed on the back side of the target.

[0364] Then, a sputtering gas mixture in the ratio of Ar:N2:He = 9:52:39 is introduced into the chamber, the sputtering voltage is adjusted to 2kW, and the sputtering process is performed by rotating a magnet. The rotational speed of the magnet is increased from an initial 100 rpm to a maximum of 150 rpm in increments of 10 rpm per minute. The thin film formation area is limited to a region on the transparent substrate surface with a length and width set to 132 mm. The sputtering process continues until the photon energy at the point where the Del_2 value according to Equation 3 is 0 reaches 2.0 eV.

[0365] After sputtering, the phase-shifted film surface of the blank mask is exposed using excimer UV light with a wavelength of 172 nm. At this time, the UV light output is 3 mW / cm² / min.2 Rise to a maximum of 7mW / cm 2 At 7mW / cm 2 Maintain power for 5 minutes.

[0366] The blank mask is then introduced into the heat treatment chamber and annealed at 1 Pa, followed by natural cooling. The temperature during annealing is increased from room temperature to a maximum of 400°C per minute, and maintained at the maximum temperature for approximately 30 minutes. After natural cooling, O2 gas is introduced into the heat treatment chamber at a rate of 1 SLM for 30 minutes. At this point, the O2 supply temperature is approximately 300°C.

[0367] A light-shielding film sputtering process is performed on the surface of the formed phase-shifted film. Specifically, a chromium target and a transparent substrate with a phase-shifted film are placed in a sputtering chamber, such that the T / S distance is 255 mm and the angle between the substrate and the target is 25 degrees. A magnet with a magnetic field of 40 mT is placed on the back side of the target.

[0368] A sputtering gas with a flow rate ratio of Ar:N2:He:CO2 = 19:11:34:37 ​​was injected into the chamber. Then, a sputtering voltage of 1.35 kW was applied, and sputtering was performed while the magnet rotated until the photon energy at the point where the phase difference between the P-wave and S-wave, measured using an elliptic polarization spectrometer, was 140°, was 1.8 to 2.0 eV, thus forming the lower layer of the light-shielding film. The sputtering process was implemented. At this point, the rotational speed of the magnet increased from an initial 100 rpm to a maximum of 150 rpm, increasing by 10 rpm per minute.

[0369] After forming the lower layer of the light-shielding film, a sputtering gas with a flow rate ratio of Ar:N2 = 57:43 is injected into the chamber. Then, a sputtering voltage of 1.85 kW is applied to rotate the magnet while sputtering continues until the photon energy at the point where the phase difference between the P-wave and S-wave is 140° as measured by an elliptic polarization spectrometer is 2.75 to 2.95 eV, thus forming the upper layer of the light-shielding film.

[0370] Two samples were prepared using the film-forming conditions described above.

[0371] Example 2: Prepared under the same conditions as in Example 1, wherein the magnetic force of the magnet used to form the phase-shift film and the light-shielding film is 45 mT, and the phase-shift film formation time is the time required for the photon energy at the point where the Del_2 value is 0 according to Equation 3 to reach 1.89 eV.

[0372] Example 3: Prepared under the same conditions as in Example 1, except that the composition of the sputtering gas used to form the phase-shifted film was changed to Ar:N2:He = 8:58:34.

[0373] Example 4: Prepared under the same conditions as in Example 1, except that the magnetic force of the magnet used to form the phase-shifting film and the light-shielding film was 42 mT, the magnet rotation speed was 150 rpm, and the deposition time of the lower layer of the light-shielding film was the time required for the photon energy at the point where the phase difference between the P-wave and S-wave is 140° as measured by ellipsometric spectroscopy to reach 1.9 eV. Furthermore, when forming the upper layer of the light-shielding film, a sputtering power of 2.75 kW was applied, and sputtering was performed until the photon energy at the point where the phase difference between the P-wave and S-wave is 140° as measured by ellipsometric spectroscopy reached 1.9 eV.

[0374] Example 5: Prepared under the same conditions as in Example 4, wherein the magnetic force applied by the magnet is 48mT, and the photon energy at the point where the Del_2 value is 0 is 1.89eV during phase-shift film formation.

[0375] Example 6: Prepared under the same conditions as in Example 4, except that the ratio of the gases contained in the sputtering gas during the formation of the phase-shifting film was changed to Ar:N2:He = 8:58:34. Additionally, the magnetic force applied to the magnets during the formation of the phase-shifting film and the light-shielding film was 37 mT.

[0376] Comparative Example 1: Prepared under the same conditions as in Example 1, wherein the magnetic force of the magnet used to form the phase-shifting film and the light-shielding film was 60 mT, the magnet rotation speed was 100 rpm, the phase-shifting film was not irradiated with UV light, and no heat treatment was performed.

[0377] Comparative Example 2: Prepared under the same conditions as Comparative Example 1, wherein the magnetic force of the magnet is applied as 20 mT.

[0378] Comparative Example 3: Prepared under the same conditions as Example 4, wherein the magnetic force of the magnet used to form the phase-shifting film and the light-shielding film was 63 mT, the magnet rotation speed was 100 rpm, the phase-shifting film was not irradiated with UV light, and no heat treatment was performed.

[0379] Comparative Example 4: Prepared under the same conditions as Comparative Example 3, except that the ratio of the gas contained in the sputtering gas during the formation of the phase-shifting film was changed to Ar:N2:He = 8:58:34. Furthermore, the magnetic force applied to the magnet during the formation of the phase-shifting film and the light-shielding film was 23 mT.

[0380] Evaluation example: Thermal fluctuation measurement

[0381] The blank masks of Examples 1 to 3 and Comparative Examples 1 and 2 were cut into 1cm × 1cm pieces, and the portion of the transparent substrate opposite to the surface on which the phase-shifting film is formed was etched in the cut blank mask. The thickness of the etched transparent substrate was 0.6mm.

[0382] After etching the transparent substrate, the TFT2 values ​​of the embodiments and comparative examples were measured using a thermomechanical analyzer. Specifically, each sample of the embodiments and comparative examples was placed in a TAINSTRUMENT Q400 thermomechanical analyzer, and the tip was placed in the sample to be measured. Then, the load on the tip was set to 0.05 N, the heating temperature was set to 10 °C / min, and the measurement temperature range was set to 30 to 200 °C before the measurement was performed.

[0383] The light-shielding film of each sample in the examples and comparative examples used for measuring the TFT2 value was removed. Specifically, the light-shielding film was removed by etching it using a chlorine-based gas as an etchant. The TFT1 value of the examples and comparative examples was then measured using a thermomechanical analyzer. The measurement conditions were the same as those used when measuring the TFT2 value.

[0384] The thermal fluctuation graph of the phase-shift film in the thickness direction according to temperature in Example 1 is shown below. Figure 4 As shown, the thermal fluctuation graph of the phase-shift film in the thickness direction according to temperature in Example 2 is as follows. Figure 5 As shown. Furthermore, the calculation results for TFT1 and TFT2 are recorded in Table 1 below.

[0385] Evaluation example: Evaluation of the optical properties of phase-shifting films measured using an ellipsometer.

[0386] The light-shielding film of the samples in the examples and comparative examples was removed by etching. The Del² value distribution, phase difference, and transmittance of each example and comparative example were measured using an elliptic polarization spectrometer (Lasertec, MPM193). When measuring the phase difference and transmittance, the wavelength of the exposure light was applied at 193 nm. The measurement results of each example and comparative example are recorded in Tables 2 and 3 below. Additionally, graphs showing the DPS values ​​and Del² value distributions measured in Examples 4 to 6 and Comparative Examples 3 and 4 are shown below. Figures 6 to 15 As shown.

[0387] Evaluation example: Contrast ratio and CD value measurement

[0388] After forming a photoresist film on the phase-shifting film surface of each sample in the examples and comparative examples, a dense quadrilateral pattern was exposed on the photoresist film surface using a Nuflare EBM 9000 model. The target CD value of the quadrilateral pattern was set to 400 nm (4X). After patterning on the photoresist film of each sample, a light-shielding film and a phase-shifting film were etched according to the developed pattern shape using an Appliedmaterials Tetra X model. The photoresist pattern was then removed.

[0389] For each sample including a phase-shift film pattern in the Examples and Comparative Examples, the contrast and normalized CD value of the pattern after exposure were measured and calculated using an AIMS 32 from Carl Zeiss. The numerical aperture (NA) was 1.35, and the illuminometer was set to crosspole 30X, output Sigma 0.8, and input / output Sigma ratio 85%. The measured data are recorded in Table 3 below.

[0390] Evaluation example: Measurement and evaluation of the elemental composition in the thickness direction of the protective layer.

[0391] For the samples in Examples 4 to 6 and Comparative Examples 3 and 4, the content of each element in the thickness direction of the protective layer was measured. Specifically, the content of each element in the thickness direction of the protective layer was measured using a Thermo Scientific K-alpha model, with an analyzer type / channel of 180° dual-focusing hemispherical analyzer / 120 channels, an Al Ka ​​micro-focused X-ray source, an energy of 1 keV, a working pressure of 1E-7 mbar, and Ar gas.

[0392] The measurement results show that the protective layer includes regions where the nitrogen content to oxygen content ratio in the thickness direction is 0.4 to 2. When these regions have a thickness of 30% to 80% of the overall thickness of the protective layer, they are rated as O; when these regions have a thickness less than 30% or greater than 80% of the overall thickness of the protective layer, they are rated as X. The measurement results are recorded in Table 3 below.

[0393] [Table 1]

[0394]

[0395] [Table 2]

[0396]

[0397] S* refers to the minimum photon energy of the incident light at the point where Del_2 is 0. B* refers to the maximum photon energy of the incident light at the point where Del_2 is 0.

[0398] [Table 3]

[0399]

[0400] In Table 1, the TFT1 and TFT2 values ​​under each measurement condition of Examples 1 to 3 all show values ​​below 0.25 μm / 100 °C. However, the TFT1 and TFT2 values ​​under each measurement condition of Comparative Examples 1 and 2 all show values ​​greater than 0.25 μm / 100 °C.

[0401] In Table 3, the transmittance of Examples 1 to 3 ranges from 5.4% to 6.9%, and the phase difference ranges from 170° to 190°. However, the transmittance of Comparative Examples 1 and 3 is less than 4%, and the phase difference is more than 200°. The transmittance of Comparative Examples 2 and 4 is more than 7%, and the phase difference is less than 170°. Therefore, it can be confirmed that the phase-shift film with adjusted Del_2 value distribution exhibits optical properties close to the desired transmittance (6%) and phase difference (180 degrees) for short-wavelength exposure light.

[0402] Examples 1 to 6 exhibited a normalized contrast ratio of 0.95 or higher and a normalized CD value of less than 1.05. In contrast, Comparative Examples 1 to 4 exhibited a normalized contrast ratio of less than 0.93 and a normalized CD value of 1.05 or higher.

[0403] In the evaluation of the elemental composition in the thickness direction of the protective layer, Examples 4 to 6 were evaluated as O, while Comparative Examples 3 and 4 were evaluated as X.

[0404] The preferred embodiments have been described in detail above. However, the scope of the claims of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art using the basic concepts of the embodiments defined in the following claims are also within the scope of the claims of the present invention.

Claims

1. A blank mask, wherein, include: transparent substrate, A phase-shifting film is disposed on the transparent substrate, and A light-shielding film is disposed on the phase-shifting film; The TFT1 value, as expressed by Equation 1 below, is 0.25 μm / 100 °C or less; [Formula 1] When analyzing the thermal fluctuations of the processed blank mask formed by processing the transparent substrate of the blank mask to a thickness of 0.6 mm and removing the light-shielding film in a thermomechanical analyzer, The measurement temperature of the thermomechanical analyzer increases from T1 to T2. The △PM refers to the change in position of the upper surface of the phase-shifting film in the thickness direction at time T2, with the upper surface of the phase-shifting film at time T1 as a reference. When PE1 is 1.5 eV and PE2 is 3.0 eV, the photon energy at the point where Del_2 is 0 according to Equation 3 is between 1.8 eV and 2.14 eV: [Formula 3] In Equation 3, When the light-blocking film is removed from the blank mask, and the surface of the phase-shifting film is measured using an ellipsometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and S-wave when the phase difference between the reflected light is less than 180°. When the phase difference between the P-wave and S-wave is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and S-wave from 360°. The PE value is the photon energy of the incident light within the range of the PE1 value to the PE2 value.

2. The blank mask according to claim 1, wherein, When T1 is 50°C and T2 is 80°C, The TFT1 value is below 0.2μm / 100℃.

3. The blank mask according to claim 1, wherein, When T1 is 50°C and T2 is 150°C, The TFT1 value is below 0.2μm / 100℃.

4. The blank mask according to claim 1, wherein, When PE1 is 3 eV and PE2 is 5 eV, the photon energy at the point where Del_2 is 0 according to Equation 3 is 3.8 eV to 4.64 eV. [Formula 3] In Equation 3, When the light-blocking film is removed from the blank mask, and the surface of the phase-shifting film is measured using an ellipsometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and S-wave when the phase difference between the reflected light is less than 180°. When the phase difference between the P-wave and S-wave is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and S-wave from 360°. The PE value is the photon energy of the incident light within the range of the PE1 value to the PE2 value.

5. The blank mask according to claim 1, wherein, The phase shift film includes: a phase difference adjustment layer and a protective layer located on the phase difference adjustment layer. The phase-shifting film comprises a transition metal, silicon, oxygen, and nitrogen. The phase difference adjustment layer contains 40 atomic% to 60 atomic% nitrogen. The protective layer contains 20 atomic% to 40 atomic% nitrogen. The protective layer includes a region in the thickness direction where the ratio of nitrogen content to oxygen content is 0.4 to 2, and the thickness of the region is 30% to 80% of the overall thickness of the protective layer.

6. The blank mask according to claim 5, wherein, The ratio of the thickness of the protective layer to the thickness of the phase-shifting film is 0.04 to 0.

09.

7. A blank mask, wherein, include: Transparent substrate; A phase-shifting film is disposed on the transparent substrate; as well as A light-shielding film is disposed on the phase-shifting film. When PE1 is 3.0 eV and PE2 is 5.0 eV, the photon energy of the incident light at the point where Del_2 is 0, as expressed by Equation 3, is 3.8 eV to 4.64 eV. [Formula 3] In Equation 3, When the light-blocking film is removed from the blank mask, and the surface of the phase-shifting film is measured using an ellipsometer with an incident angle of 64.5°, the DPS value is the phase difference between the P-wave and S-wave when the phase difference between the reflected light is less than 180°. When the phase difference between the P-wave and S-wave is greater than 180°, the DPS value is obtained by subtracting the phase difference between the P-wave and S-wave from 360°. The PE value is the photon energy of the incident light within the range of PE1 to PE2. When the PE1 value is 1.5 eV and the PE2 value is 3.0 eV, the photon energy of the incident light at the point where the Del_2 value is 0 is 1.8 eV to 2.14 eV.

8. The blank mask according to claim 7, wherein, When the PE1 value is 1.5 eV and the PE2 value is the minimum photon energy of the incident light at the point where the Del_2 value is 0, the average value of the Del_2 value is 78° / eV to 98° / eV.

9. The blank mask according to claim 7, wherein, When the PE1 value is the minimum photon energy of the incident light at the point where the Del_2 value is 0, and the PE2 value is the maximum photon energy of the incident light at the point where the Del_2 value is 0, the average value of the Del_2 value is -65° / eV to -55° / eV.

10. The blank mask according to claim 7, wherein, When the PE1 value is the maximum value of the photon energy of the incident light at the point where the Del_2 value is 0, and the PE2 value is 5.0 eV, the average value of the Del_2 value is 60° / eV to 120° / eV.

11. The blank mask according to claim 7, wherein, When the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of the Del_2 value is 105° / eV to 300° / eV.

12. The blank mask according to claim 11, wherein, The photon energy at the point where the Del_2 value is the maximum is above 4.5 eV.

13. A photomask, wherein, The photomask is made from the blank mask according to claim 1 or 7.

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