Blank mask

Abstract

The invention relates to a mask blank. The blank mask includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light shielding film provided on the phase shift film, the photon energy of incident light at a point where Del1 represented by the following formula 7 is 0 when the PE1 value is 3.0 eV and the PE2 value is 5.0 eV being 3.8 eV to 4.64 eV; [Equation 7] In Equation 7, when the light shielding film is removed from the blank mask, an incidence angle of 64.5 DEG is applied, and the surface of the phase shift film is measured by an elliptical polarization spectrometer, 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 180 DEG or less, and 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 greater than 180 DEG. The DPS value is a value obtained by subtracting a phase difference between a P-wave and an S-wave from 360 DEG, and the PE value is a photon energy of incident light in a range of PE1 to PE2.

Description

[0001] This application is a divisional application of the patent application with application number 202111651440X, application date December 30, 2021, and invention name “Blank mask and photomask using the same”. Technical Field

[0002] Embodiments relate to a blank mask and a photomask using the same. Background Art

[0003] As semiconductor devices and the like become increasingly integrated, their circuit patterns need to be miniaturized. Consequently, the importance of photolithography, a technique for developing circuit patterns on a wafer surface using a photomask, has become increasingly prominent.

[0004] In order to develop a miniaturized circuit pattern, it is necessary to use an exposure light source with a short wavelength in the exposure process. Recently used exposure light sources include ArF excimer laser (wavelength 193 nm) and the like.

[0005] In addition, photomasks include binary masks and phase shift masks.

[0006] A binary mask has a structure with a light-shielding film pattern formed on a transparent substrate. In this binary mask, exposure light passes through the light-transmitting portion of the surface with the pattern, while the light-shielding portion, which does include the light-shielding film, blocks the exposure light, thereby exposing the pattern to the resist film on the wafer surface. However, as the pattern becomes finer, binary masks can become difficult to achieve due to light diffraction at the edges of the light-transmitting portion during exposure.

[0007] Phase-shift masks include Levenson type, Outrigger type, and half-tone type. A half-tone phase-shift mask has a structure in which a pattern formed by a semi-transparent film is formed on a transparent substrate. In a half-tone phase-shift mask, on the surface where the pattern is formed, the exposure light transmits the translucent portion that does not include the semi-translucent layer, and the attenuated exposure light transmits the semi-translucent portion that includes the semi-translucent layer. The attenuated exposure light has a phase difference compared to the exposure light that passes through the translucent portion. Therefore, the diffracted light generated at the edge of the translucent portion cancels out the exposure light that passes through the semi-translucent portion, allowing the phase-shift mask to form a finer pattern on the wafer surface.

[0008] Prior art documents include Korean Patent No. 10-1360540, U.S. Patent No. 2004-0115537, and Japanese Patent No. 2018-054836. Summary of the Invention

[0009] Problems to be solved by the invention

[0010] The embodiment provides a blank mask or the like capable of easily forming a fine pattern.

[0011] Means used to solve problems

[0012] A blank mask according to an embodiment includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light shielding film disposed on the phase shift film.

[0013] The blank mask was analyzed using normal mode XRD.

[0014] When the normal mode XRD analysis is performed, 2θ of the maximum peak of X-ray intensity measured after reflection on the upper surface side of the phase shift film is 15° to 30°.

[0015] When the normal mode XRD analysis is performed, 2θ of the maximum peak of X-ray intensity measured after reflection on the lower surface side of the transparent substrate is 15° to 30°.

[0016] The blank mask has an AI1 value expressed by the following Formula 1 of 0.9 to 1.1:

[0017] [Formula 1]

[0018]

[0019] In Formula 1, XM1 is the maximum value of X-ray intensity measured when the upper surface of the phase shift film is subjected to the normal mode XRD analysis.

[0020] The XQ1 is a maximum value of X-ray intensity measured when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0021] The blank mask can be analyzed using fixed-mode XRD.

[0022] In the fixed-mode XRD analysis, 2θ of a maximum peak of X-ray intensity measured after reflection on the upper surface side of the phase shift film, ie, a first peak, may be 15° to 25°.

[0023] In the fixed mode XRD analysis, 2θ of a maximum peak of X-ray intensity measured after reflection on the lower surface side of the transparent substrate, that is, a second peak, may be 15° to 25°.

[0024] In the blank mask, the AI2 value expressed by the following Formula 2 may be 0.9 to 1.1:

[0025] [Formula 2]

[0026]

[0027] In the formula 2, XM2 is the intensity value of the first peak, and XQ2 is the intensity value of the second peak.

[0028] In the blank mask, the AI3 value expressed by the following Formula 3 may be 0.9 to 1.1:

[0029] [Formula 3]

[0030]

[0031] In Formula 3, AM1 is the area of ​​a region where 2θ is 15° to 30° in an X-ray intensity diagram measured after reflection when a normal mode XRD analysis is performed on the upper surface of the phase shift film.

[0032] The AQ1 is the area of ​​a region where 2θ is 15° to 30° in an X-ray intensity diagram measured after reflection when a normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0033] In the blank mask, the AI4 value represented by the following Formula 4 may be 0.9 to 1.1:

[0034] [Formula 4]

[0035]

[0036] In Formula 4, XM4 is the intensity of reflected X-rays when 2θ is 43° in the normal mode XRD analysis performed on the upper surface of the phase shift film.

[0037] The XQ4 is the intensity of reflected X-rays when 2θ is 43° in the normal mode XRD analysis performed on the lower surface of the transparent substrate.

[0038] In the case of normal mode XRD analysis performed through the light-shielding film, the X-ray intensity measured after reflection may have a maximum value when 2θ is 15° to 30°.

[0039] In the case where the XRD analysis is performed through the lower surface of the transparent substrate, the X-ray intensity measured after reflection may have a maximum value when 2θ is 15° to 30°.

[0040] In the blank mask, the AI5 value expressed by the following Formula 5 may be 0.9 to 0.97:

[0041] [Formula 5]

[0042]

[0043] In the above formula (5), XC1 is the maximum value of the X-ray intensity measured on the upper surface of the light-shielding film.

[0044] The XQ1 is the maximum value of the X-ray intensity measured on the lower surface of the transparent substrate.

[0045] In the blank mask, the AI6 value represented by the following Formula 6 may be 1.05 to 1.4:

[0046] [Formula 6]

[0047]

[0048] In the formula 6, XC4 is the intensity of X-rays reflected when 2θ is 43° when the normal mode XRD analysis is performed on the upper surface of the light shielding film.

[0049] The XQ4 is the intensity of X-rays reflected when 2θ is 43° when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0050] In the blank mask, when PE1 is 1.5 eV and PE2 is 3 eV, the photon energy at the point where the Del_1 value is 0 is 1.8 to 2.14 eV according to the following formula 7:

[0051] [Formula 7]

[0052]

[0053] In Formula 7, when the phase shift film is measured using an ellipsometer at an incident angle of 64.5°, when the phase difference between the P wave and the S wave of the reflected light is 180° or less, the DPS value is the phase difference between the P wave and the S wave; and when the phase difference between the P wave and the S wave of the reflected light is greater than 180°, the DPS value is a value obtained by subtracting the phase difference between the P wave and the S wave from 360°.

[0054] The PE value is the photon energy of the incident light within the range from the PE1 value to the PE2 value.

[0055] In the blank mask, when the PE1 value is 3.0 eV and the PE2 value is 5.0 eV, the photon energy at the point where the Del_1 value is 0 may be 3.8 to 4.64 eV.

[0056] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is the minimum value of the photon energy of the incident light at the point where the Del_1 value is 0, the average value of the Del_1 value may be 78 to 98° / eV.

[0057] In the blank mask, when the PE1 value is the minimum value among the photon energies of the incident light at the point where the Del_1 value is 0 and the PE2 value is the maximum value among the photon energies of the incident light at the point where the Del_1 value is 0, the average value of the Del_1 value can be -65 to -55° / eV.

[0058] In the blank mask, when the PE1 value is the maximum value among the photon energies of the incident light at the point where the Del_1 value is 0 and the PE2 value is 5.0 eV, the average value of the Del_1 value may be 60 to 120° / eV.

[0059] 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_1 value may be 105 to 300° / eV.

[0060] In the blank mask, the photon energy at the point where the Del_1 value is maximum may be 4.5 eV or greater.

[0061] The phase shift film can protect the phase difference adjusting layer and the protection layer located on the phase difference adjusting layer.

[0062] The phase shift film may include transition metal, silicon, oxygen, and nitrogen.

[0063] The phase difference adjusting layer may include 40 to 60 atomic % of nitrogen.

[0064] The protective layer may contain 20 to 40 atomic % of nitrogen.

[0065] The protective layer includes a region in which a ratio of nitrogen content to oxygen content in a thickness direction is 0.4 to 2.

[0066] The thickness of the region may be 30 to 80% of the overall thickness of the protective layer.

[0067] A blank mask according to another embodiment includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light shielding film disposed on the phase shift film.

[0068] In the blank mask, 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_1 is 0, expressed by the following equation 7, is 3.8 eV to 4.64 eV:

[0069] [Formula 7]

[0070]

[0071] In Formula 7, when the light-shielding film is removed from the blank mask and an incident angle of 64.5° is applied to measure the surface of the phase shift film using an ellipsometer, when the phase difference between the P wave and the S wave of the reflected light is less than 180°, 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 greater than 180°, the DPS value is the value obtained by subtracting the phase difference between the P wave and the S wave from 360°.

[0072] The PE value is the photon energy of the incident light within the range from PE1 to PE2.

[0073] 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_1 value is 0 may be 1.8 eV to 2.14 eV.

[0074] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is the minimum value of the photon energy of the incident light at the point where the Del_1 value is 0, the average value of the Del_1 value may be 78° / eV to 98° / eV.

[0075] In the blank mask, when the PE1 value is the minimum value of the photon energy of the incident light at the point where the Del_1 value is 0, and the PE2 value is the maximum value of the photon energy of the incident light at the point where the Del_1 value is 0, the average value of the Del_1 value can be -65° / eV to -55° / eV.

[0076] In the blank mask, when the PE1 value is the maximum value among the photon energies of the incident light at the point where the Del_1 value is 0 and the PE2 value is 5.0 eV, the average value of the Del_1 value may be 60° / eV to 120° / eV.

[0077] 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_1 value may be 105° / eV to 300° / eV.

[0078] In the blank mask, the photon energy at the point where the Del_1 value reaches the maximum value may be 4.5 eV or greater.

[0079] The blank mask can be analyzed using normal mode XRD.

[0080] When performing the normal mode XRD analysis, 2θ of the maximum peak of X-ray intensity measured after reflection in the phase shift film direction may be between 15° and 30°.

[0081] When the normal mode XRD analysis is performed, the intensity of X-rays measured after reflection in the lower surface direction of the transparent substrate may have a maximum value when 2θ is between 15° and 30°.

[0082] In the blank mask, the AI1 value represented by the following Formula 1 may be 0.9 to 1.1:

[0083] [Formula 1]

[0084]

[0085] In Formula 1, XM1 is the maximum value of X-ray intensity measured when the upper surface of the phase shift film is subjected to the normal mode XRD analysis.

[0086] The XQ1 is a maximum value of X-ray intensity measured when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0087] The blank mask can be analyzed using fixed-mode XRD.

[0088] In the XRD analysis of the fixed mode, the maximum peak of the X-ray intensity measured after reflection from the phase shift film side, that is, the 2θ of the first peak may be 15° to 25°.

[0089] In the fixed-mode XRD analysis, a maximum peak of X-ray intensity measured after reflection from the transparent substrate side, that is, a 2θ of a second peak may be 15° to 25°.

[0090] In the blank mask, the AI2 value expressed by the following Formula 2 may be 0.9 to 1.1:

[0091] [Formula 2]

[0092]

[0093] In the formula 2, XM2 is the intensity value of the first peak, and XQ2 is the intensity value of the second peak.

[0094] In one embodiment, the AI3 value of the photomask expressed by the following formula 3 may be 0.9 to 1.1:

[0095] [Formula 3]

[0096]

[0097] In Formula 3, AM1 is the area of ​​a region where 2θ is 15° to 30° in an X-ray intensity diagram measured after reflection when a normal mode XRD analysis is performed on the upper surface of the phase shift film.

[0098] The AQ1 is the area of ​​a region where 2θ is 15° to 30° in an X-ray intensity diagram measured after reflection when a normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0099] In one embodiment, the AI4 value of the photomask expressed by the following formula 4 may be 0.9 to 1.1:

[0100] [Formula 4]

[0101]

[0102] In Formula 4, XM4 is the intensity of reflected X-rays when 2θ is 43° in the normal mode XRD analysis performed on the upper surface of the phase shift film.

[0103] The XQ4 is the intensity of reflected X-rays when 2θ is 43° in the normal mode XRD analysis performed on the lower surface of the transparent substrate.

[0104] In the case of normal mode XRD analysis performed through the light-shielding film, the X-ray intensity measured after reflection may have a maximum value when 2θ is between 15° and 30°.

[0105] In the case where the XRD analysis is performed through the lower surface of the transparent substrate, the X-ray intensity measured after reflection may have a maximum value when 2θ is between 15° and 30°.

[0106] In the blank mask, the AI5 value expressed by the following Formula 5 may be 0.9 to 0.97:

[0107] [Formula 5]

[0108]

[0109] In the above formula (5), XC1 is the maximum value of the X-ray intensity measured through the upper surface of the light-shielding film.

[0110] The XQ1 is the maximum value of the X-ray intensity measured through the lower surface of the transparent substrate.

[0111] In the blank mask, the AI6 value represented by the following Formula 6 may be 1.05 to 1.4:

[0112] [Formula 6]

[0113]

[0114] In the formula 6, XC4 is the intensity of X-rays reflected when 2θ is 43° when the normal mode XRD analysis is performed on the upper surface of the light shielding film.

[0115] The XQ4 is the intensity of X-rays reflected when 2θ is 43° when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0116] The phase shift film may include a phase difference adjusting layer and a protective layer located on the phase difference adjusting layer.

[0117] The phase shift film may include transition metal, silicon, oxygen, and nitrogen.

[0118] The phase difference adjusting layer may include 40 to 60 atomic % of nitrogen.

[0119] The protective layer may contain 20 to 40 atomic % of nitrogen.

[0120] The protective layer may include a region where a ratio of a nitrogen content to an oxygen content in a thickness direction is 0.4 to 2.

[0121] The thickness of the region may be 30 to 80% of the overall thickness of the protective layer.

[0122] A photomask according to yet another embodiment includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light shielding film disposed on at least a portion of the phase shift film.

[0123] The photomask was analyzed using normal mode XRD.

[0124] In the normal mode XRD analysis, 2θ of a maximum peak of X-ray intensity measured after reflection on the upper surface side of the phase shift film is 15° to 30°.

[0125] In the normal mode XRD analysis, 2θ of a maximum peak of X-ray intensity measured after reflection on the lower surface side of the transparent substrate is 15° to 30°.

[0126] The AI1 value expressed by the following formula 1 is 0.9 to 1.1:

[0127] [Formula 1]

[0128]

[0129] In the formula 1, XM1 is the maximum value of the X-ray intensity measured when the normal mode XRD analysis is performed on the upper surface of the phase shift film.

[0130] The XQ1 is a maximum value of X-ray intensity measured when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0131] A photomask according to yet another embodiment includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light shielding film disposed on the phase shift film.

[0132] When the PE1 value is 3.0 eV and the PE2 value is 5.0 eV, the photon energy of incident light at a point where Del_1 is 0, which is expressed by the following equation 7, is 3.8 to 4.64 eV.

[0133] [Formula 7]

[0134]

[0135] In Formula 7, when the light-shielding film is removed from the photomask and the surface of the phase shift film is measured using a spectroscopic ellipsometer at an incident angle of 64.5°, if the phase difference between the P wave and the S wave of the reflected light is 180° or less, the DPS value is the phase difference between the P wave and the S wave. If the phase difference between the P wave and the S wave of the reflected light is greater than 180°, the DPS value is the value obtained by subtracting the phase difference between the P wave and the S wave from 360°.

[0136] The PE value is the photon energy of the incident light within the range from PE1 to PE2.

[0137] Effects of the Invention

[0138] The blank mask and the like of the embodiment can minimize the optical distortion caused by the difference in crystal properties between the phase shift film and the transparent substrate, and can also reduce process errors caused by the optical distortion during the exposure and development processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0139] Figure 1 FIG. 1 is a cross-sectional view showing a blank mask according to an embodiment.

[0140] Figure 2 is a schematic diagram illustrating a normal mode X-ray diffraction (XRD) analysis process.

[0141] Figure 3 FIG. 1 is a schematic diagram showing X-ray intensity measured by performing normal mode XRD analysis on a phase shift film in a blank mask according to an embodiment.

[0142] Figure 4 FIG. 1 is a schematic diagram showing X-ray intensity measured by performing normal mode XRD analysis on a transparent substrate in a blank mask according to an embodiment.

[0143] Figure 5 is a schematic diagram showing the XRD analysis process of a fixed pattern.

[0144] Figure 6 FIG. 1 is a schematic diagram showing X-ray intensity measured by performing a fixed-mode XRD analysis on a phase shift film in a blank mask according to an embodiment.

[0145] Figure 7 FIG. 1 is a schematic diagram showing X-ray intensity measured by performing a fixed-mode XRD analysis on a transparent substrate in a blank mask according to an embodiment.

[0146] Figure 8 FIG. 1 is a schematic diagram showing X-ray intensity measured by performing normal mode XRD analysis on a light-shielding film in a blank mask according to an embodiment.

[0147] Figure 9 is a cross-sectional view showing a blank mask according to another embodiment.

[0148] Figure 10 Schematic diagram illustrating the principle of measuring the phase difference between the P wave and the S wave of light reflected from a phase shift film using spectroscopic ellipsometer.

[0149] Figure 11 is a cross-sectional view showing a photomask according to another embodiment.

[0150] Figure 12 This is a graph showing the distribution of DPS values ​​according to photon energy in measured Example 4.

[0151] Figure 13 This is a graph showing the distribution of Del_1 values ​​according to photon energy in measured Example 4.

[0152] Figure 14 This is a graph showing the distribution of DPS values ​​according to photon energy in measured Example 5.

[0153] Figure 15 This is a graph showing the distribution of Del_1 values ​​according to photon energy in measured Example 5.

[0154] Figure 16 This is a graph showing the distribution of DPS values ​​according to photon energy in measured Example 6.

[0155] Figure 17 This is a graph showing the distribution of Del_1 values ​​according to photon energy in measured Example 6.

[0156] Figure 18 This is a graph showing the distribution of DPS values ​​according to photon energy measured in Comparative Example 3.

[0157] Figure 19This is a graph showing the distribution of Del_1 values ​​according to photon energy measured in Comparative Example 3.

[0158] Figure 20 This is a graph showing the distribution of DPS values ​​according to photon energy measured in Comparative Example 4.

[0159] Figure 21 This is a graph showing the distribution of Del_1 values ​​according to photon energy measured in Comparative Example 4.

[0160] Description of Reference Numerals

[0161] 100: Blank mask

[0162] 10: Transparent substrate

[0163] 20: Phase shift film

[0164] 21: Phase Difference Adjustment Layer

[0165] 22: Protective layer

[0166] 30: Light-shielding film

[0167] 60: X-ray generator

[0168] 70: Detector

[0169] 80: Sample

[0170] 200: Photomask

[0171] TA: light-transmitting part

[0172] NTA: semi-transparent part θ: incident angle

[0173] N: Normal

[0174] L i : Incident light

[0175] L r : Reflected light

[0176] P: P-wave component of incident light

[0177] S: S-wave component of incident light P`: P-wave component of reflected light S`: S-wave component of reflected light

[0178] △: Phase difference between the P wave and S wave of the reflected light. DETAILED DESCRIPTION

[0179] The embodiments are described in detail below so that those skilled in the art can easily implement the embodiments. However, the embodiments can be implemented in various forms and are not limited to the embodiments described here.

[0180] When used in this specification, terms indicating degree such as "approximately" and "substantially" indicate inherent manufacturing and material tolerances in the meaning mentioned, they are interpreted as that numerical value or a value close to that numerical value, and are intended to prevent certain unscrupulous infringers from making improper use of the disclosure content related to the accurate or absolute numerical values ​​disclosed to help understand the present invention.

[0181] Throughout the present specification, the term "combination thereof" included in the Markush form expression means a mixture or combination of one or more selected from the group consisting of the components described in the Markush form expression, and thus means that one or more selected from the group consisting of the components are included.

[0182] Throughout the specification of the present invention, the description of "A and / or B" means "A, B, or A and B."

[0183] Throughout the specification of the present invention, unless otherwise specified, terms such as "first", "second" or "A", "B" and the like are used to distinguish the same terms.

[0184] In this specification, B is located on A means that B is on A or B is on A with another layer present between A and B, and should not be construed as the surfaces of B and A being in contact with each other.

[0185] In this specification, unless otherwise specified, singular expressions should be construed as having a singular or plural meaning as interpreted in the context.

[0186] In this specification, the accompanying drawings are used to illustrate the embodiments, and parts thereof may be exaggerated or omitted and are not drawn to scale.

[0187] In this specification, a transparent portion (TA) refers to a region on a transparent substrate, on a photomask surface on which a pattern is formed, that does not substantially include a phase shift film, thereby allowing exposure light to pass therethrough, and a semi-transparent portion (NTA) refers to a region that substantially includes a phase shift film, thereby allowing attenuated exposure light to pass therethrough (see Figure 11 ).

[0188] The manufacturing process of semiconductor devices involves forming an exposure pattern on a semiconductor wafer to create a designed pattern. Specifically, a photomask containing the designed pattern is placed on a semiconductor wafer coated with a resist layer. When a light source is used to expose the semiconductor wafer, the resist layer is treated with a developer solution to form the designed pattern.

[0189] As semiconductors become increasingly integrated, increasingly fine circuit patterns are required. Exposure light with a shorter wavelength than conventional exposure light can be used to form fine patterns on semiconductor wafers. For example, ArF excimer laser light (wavelength 193 nm) can be used to form fine patterns.

[0190] As circuit patterns become finer, a film included in the photomask and forming a pattern is required to have improved optical characteristics.

[0191] In addition, a light source that generates exposure light of a short wavelength may require a high output. Such a light source can increase the temperature of a photomask included in a semiconductor device manufacturing apparatus during an exposure process.

[0192] The film included in the photomask and forming a pattern may have a characteristic that physical properties such as thickness and height vary with temperature. The film included in the photomask and forming a pattern needs to have a characteristic with less thermal fluctuation.

[0193] Photomasks are formed by patterning a mask blank. Therefore, the properties of the mask blank may affect the physical properties of the photomask. Furthermore, during the mask blank manufacturing process, the mask blank may undergo oxidation and heat treatments, resulting in differences in the properties of the thin film immediately after formation and in the finished mask blank.

[0194] Optical and thermal characteristics of each layer included in the blank mask may be improved by appropriately adjusting crystal characteristics of each layer included in the blank mask.

[0195] The inventors of the embodiment completed the embodiment by experimentally confirming that by adjusting the crystal properties of the film included in the blank mask, it is possible to suppress the temperature rise caused by the light source generating short-wavelength exposure light or the reduction in the resolution of the photomask caused by the difference in optical properties between the various films.

[0196] Hereinafter, embodiments will be described in more detail.

[0197] Figure 1 1 is a cross-sectional view showing a blank mask of an embodiment. Figure 1 An embodiment is described.

[0198] The blank mask 100 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 .

[0199] The material of the transparent substrate 10 is not limited as long as it is translucent to the exposure light and can be used in a photomask. Specifically, the transparent substrate 10 can have a transmittance of 85% or greater for exposure light with a wavelength of 200 nm or less. Such transmittance can be 87% or greater. The transparent substrate 10 can have a transmittance of 85% or greater for ArF light. Such transmittance can be 87% or greater. For example, a synthetic quartz substrate can be used for the transparent substrate 10. In this case, the transparent substrate 10 can suppress attenuation of light passing through it.

[0200] In addition, the transparent substrate 10 can reduce the occurrence of optical distortion by adjusting surface properties such as flatness and roughness.

[0201] The phase shift film 20 may be located on the front side of the transparent substrate 10 .

[0202] In the blank mask 100, a light shielding film 30 is located on the phase shift film. When the phase shift film 20 is etched in a pattern, the light shielding film 30 can serve as an etching mask for the phase shift film 20. Furthermore, the light shielding film 30 can block the transmission of exposure light incident from the back surface of the transparent substrate 10.

[0203] Crystal properties of phase shift films

[0204] A blank mask according to an embodiment includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light shielding film disposed on at least a portion of the phase shift film.

[0205] The blank mask was analyzed by normal mode XRD.

[0206] In the XRD analysis in the normal mode, 2θ of the maximum peak of the X-ray intensity measured after reflection in the direction of the phase shift film is 15° to 30°.

[0207] In normal mode XRD analysis, 2θ of a maximum peak of X-ray intensity measured after reflection in the direction of the transparent substrate is 15° to 30°.

[0208] The AI1 value expressed by the following formula 1 is 0.9 to 1.1:

[0209] [Formula 1]

[0210]

[0211] In Formula 1, XM1 is the maximum value of X-ray intensity measured when performing the normal mode XRD analysis on the upper surface of the phase shift film, and XQ1 is the maximum value of X-ray intensity measured when performing the normal mode XRD analysis on the lower surface of the transparent substrate.

[0212] The optical characteristics of the phase shift film 20 depend on various factors such as the composition of the elements constituting the phase shift film 20, the film density, and the film thickness. Therefore, the phase shift film 20 is designed and formed by considering these factors to maximize the resolution of the pattern developed on the semiconductor wafer.

[0213] On the other hand, the temperature of the phase shift film 20 may increase due to heat generated from the light source in the exposure process and the thickness value, stress, etc. of the phase shift film 20 may vary due to the heat.

[0214] The phase shift film 20 and the transparent substrate 10 may exhibit different thermal fluctuation characteristics. This is believed to be due to differences in the types of elements contained in the phase shift film 20, the content of each element, and the crystal structure compared to the transparent substrate 10. These differences can lead to reduced photomask resolution. Specifically, during long, repeated exposure processes, the transparent substrate 10 and the phase shift film 20 may exhibit different dimensional changes and stress fluctuations. This can cause optical path distortion, particularly at the interface between the transparent substrate 10 and the phase shift film 20.

[0215] The embodiment can reduce optical distortion occurring at the interface between the transparent substrate 10 and the phase shift film 20 by controlling the crystal characteristics of the phase shift film 20 to be more similar to the transparent substrate 10 .

[0216] The crystal properties of the phase shift film 20 can be adjusted by controlling factors such as the type of elements constituting the phase shift film 20, the content of each element, the magnetic field strength in the sputtering process, the substrate rotation speed, the voltage applied to the target material, the atmosphere gas composition, the sputtering temperature, and the post-processing process conditions.

[0217] In particular, embodiments can form the phase shift film 20 using a sputtering device by providing a magnet in the sputtering device to generate a magnetic field, thereby distributing plasma over the entire surface of the target material in the chamber. Crystalline properties of the phase shift film formed in the sputtering device can be adjusted by controlling the magnetic field distribution and intensity.

[0218] Figure 2 It is a schematic diagram showing the XRD analysis process of the normal mode. Figure 2 An embodiment is described.

[0219] The crystal properties of the phase shift film and the transparent substrate can be analyzed by X-ray diffraction (XRD) analysis.

[0220] Before performing XRD analysis, remove the light-shielding film on the phase-shift film. If there is another thin film between the phase-shift film and the light-shielding film, remove it. This means that the upper surface of the phase-shift film is exposed by removing the light-shielding film. For example, etching can be used to remove the thin film.

[0221] The XRD analysis can be performed in a normal mode. The normal mode XRD analysis is a θ-2θ mode. In the normal mode XRD analysis, X-rays generated by the X-ray generator 60 are emitted to the sample 80, and the X-rays reflected from the sample 80 are detected by the detector 70.

[0222] At this time, the X-ray generator 60 emits X-rays at a predetermined incident angle θ toward the sample 80. The incident angle θ is the angle between the direction of the X-rays emitted from the X-ray generator 60 and the horizontal plane of the sample 80. Furthermore, the X-ray generator 60 emits X-rays toward the sample 80 while changing the incident angle θ.

[0223] Detector 70 is located at a position opposite to X-ray generator 60, with the position of X-rays incident on sample 80 as a reference. Detector 70 detects X-rays reflected from sample 80 that have a predetermined emission angle θ. The emission angle θ is the angle between the direction of the X-rays reflected from sample 80 and the horizontal plane of sample 80.

[0224] In addition, the detector 70 moves in a scanning direction corresponding to the X-ray generator 60. That is, when the X-ray generator scans the sample 80, the detector 70 moves so that the incident angle θ is the same as the exit angle θ. In normal mode XRD analysis, the X-ray generator 60 and the detector 70 can move on the same plane in a manner such that the incident angle θ and the exit angle θ are the same. In addition, the X-ray generator 60 can move in a manner such that the distance between the position where the X-rays of the sample 80 are incident is constant. In addition, the detector 70 can move in a manner such that the distance between the position where the X-rays of the sample 80 are reflected is constant. That is, the X-ray generator 60 and the detector 70 can move in the form of an arc.

[0225] In the normal mode XRD analysis, the X-ray source may be a copper target. In the normal mode XRD analysis, the wavelength of the X-rays may be approximately 1.542 nm. In the normal mode XRD analysis, the voltage for generating the X-rays may be approximately 45 kV. In the normal mode XRD analysis, the current for generating the X-rays may be approximately 200 mA. In the normal mode XRD analysis, the measurement range of 2θ may be approximately 10° to approximately 100°. The normal mode XRD analysis may be based on 2θ and measured once every approximately 0.05° change. In the normal mode XRD analysis, the scanning speed of the X-ray generator 60 and the detector 70 may be approximately 5° / min.

[0226] Figure 3 FIG. 1 is a schematic diagram showing X-ray intensity measured by performing normal mode XRD analysis on a phase shift film in a blank mask according to an embodiment. Figure 4 1 is a schematic diagram showing the X-ray intensity measured by performing normal mode XRD analysis on a transparent substrate in a blank mask of an embodiment. Figure 3 and 4 An embodiment is described.

[0227] When normal mode XRD analysis is performed on the phase shift film, the 2θ of the maximum peak of the X-ray intensity measured after reflection can be 15° to 30°. When normal mode XRD analysis is performed on the back surface (lower surface) of the transparent substrate, the 2θ of the maximum peak of the X-ray intensity measured after reflection can be 15° to 30°.

[0228] Hereinafter, performing XRD analysis on a phase-shift film refers to performing XRD analysis on a blank mask on the phase-shift film, also referred to as performing XRD analysis in the direction of the phase-shift film. Similarly, performing XRD analysis on a transparent substrate refers to performing XRD analysis on the bottom surface of the transparent substrate, also referred to as performing XRD analysis in the direction of the transparent substrate.

[0229] When the phase shift film is subjected to normal mode XRD analysis, the 2θ of the maximum peak of the X-ray intensity measured after reflection can be 20° to 25°. When the transparent substrate is subjected to normal mode XRD analysis, the 2θ of the maximum peak of the X-ray intensity measured after reflection can be 20° to 25°.

[0230] Furthermore, the absolute value of the difference between the 2θ of the maximum peak value of X-ray intensity measured after reflection when performing normal-mode XRD analysis on the phase shift film and the 2θ of the maximum peak value of X-ray intensity measured after reflection when performing normal-mode XRD analysis on the transparent substrate may be 5° or less. The absolute value may be 3° or less. The absolute value may be 1° or less.

[0231] In the blank mask, the AI1 value of the following formula 1 may be 0.9 to 1.1:

[0232] [Formula 1]

[0233]

[0234] The XM1 is the maximum value of the X-ray intensity measured when performing the normal mode XRD analysis on the upper surface of the phase shift film, and the XQ1 is the maximum value of the X-ray intensity measured when performing the normal mode XRD analysis on the lower surface of the transparent substrate.

[0235] The AI1 value may be 0.95 to 1.05. The AI1 value may be 0.97 to 1.03. The AI1 value may be 0.98 to 1.02. The AI1 value may be 0.99 to 1.01. In this case, it is possible to suppress a decrease in the resolution of the photomask due to long-term temperature changes during the exposure process.

[0236] In the blank mask, the AI3 value expressed by the following formula 3 may be 0.9 to 1.1:

[0237] [Formula 3]

[0238]

[0239] Among them, the AM1 is the area of ​​the region where 2θ is 15° to 30° in the X-ray intensity measured after reflection when performing XRD analysis on the upper surface of the phase shift film, and the AQ1 is the area of ​​the region where 2θ is 15° to 30° in the X-ray intensity measured after reflection when performing XRD analysis on the lower surface of the transparent substrate.

[0240] The AI3 value may be 0.95 to 1.05. The AI3 value may be 0.97 to 1.03. The AI3 value may be 0.98 to 1.02. The AI3 value may be 0.99 to 1.01. In this case, the difference in crystal properties between the transparent substrate and the phase shift film is reduced, thereby suppressing degradation of the patterned phase shift film due to temperature changes.

[0241] In the blank mask, the AI4 value expressed by the following formula 4 may be 0.9 to 1.1:

[0242] [Formula 4]

[0243]

[0244] Among them, the XM4 is the intensity of the reflected X-ray when 2θ is 43° when the XRD analysis is performed on the upper surface of the phase shift film, and the XQ4 is the intensity of the reflected X-ray when 2θ is 43° when the XRD analysis is performed on the lower surface of the transparent substrate.

[0245] The AI4 value may be 0.95 to 1.05. The AI4 value may be 0.97 to 1.03. The AI4 value may be 0.98 to 1.02. The AI4 value may be 0.99 to 1.01.

[0246] In this case, the difference in thermal fluctuation characteristics between the transparent substrate and the phase shift film can be effectively reduced.

[0247] Figure 5 Schematic diagram showing the XRD analysis process of the fixed mode. Figure 5 An embodiment is described.

[0248] The XRD analysis may employ a fixed-mode XRD analysis. In the fixed-mode XRD analysis, X-rays generated by the X-ray generator 60 are emitted to the sample 80 , and the X-rays reflected from the sample 80 are detected by the detector 70 .

[0249] At this time, in the fixed mode XRD analysis, the X-ray generator 60 emits X-rays at a fixed incident angle (e.g., 1°) toward the sample 80. The incident angle is the angle between the direction of the X-rays emitted from the X-ray generator 60 and the horizontal plane of the sample 80.

[0250] Detector 70 is positioned opposite the position where X-ray generator 60 is positioned, with reference to the position at which X-rays incident on sample 80. Detector 70 detects X-rays reflected from sample 80 that have a predetermined exit angle θ. The exit angle θ is the angle between the direction of the X-rays reflected from sample 80 and the horizontal plane of sample 80.

[0251] Detector 70 is movable to detect X-rays emitted at various emission angles θ. In fixed-mode XRD analysis, the measurement locations of the X-ray generator 60, detector 70, and sample 80 are arranged on the same plane. Furthermore, detector 70 is movable within this plane. Furthermore, detector 70 can be moved to maintain a constant distance from the location in sample 80 where the X-rays are reflected. In other words, detector 70 can be moved in an arc.

[0252] In the fixed-mode XRD analysis, the incident angle is approximately 1°, the X-ray source is a copper target, the wavelength of the X-rays is approximately 1.542 nm, the voltage for generating the X-rays is approximately 45 kV, the current for generating the X-rays is approximately 200 mA, the measurement range of 2θ is approximately 10° to approximately 100°, and a measurement is performed every time the 2θ changes by approximately 0.05°. The scanning speed of the detector 70 is approximately 5° / min.

[0253] Figure 6 FIG. 1 is a schematic diagram showing X-ray intensity measured by performing a fixed-mode XRD analysis on a phase shift film in a blank mask according to an embodiment. Figure 7 Schematic diagram showing the X-ray intensity measured by performing XRD analysis on a transparent substrate in a fixed mode in a blank mask of an embodiment. Figure 6 and 7 An embodiment is described.

[0254] When performing fixed-mode XRD analysis, the maximum peak of X-ray intensity measured after reflection from the phase shift film side, i.e., the first peak, can have a 2θ angle of 15° to 25°. When performing fixed-mode XRD analysis, the maximum peak of X-ray intensity measured after reflection from the transparent substrate side, i.e., the second peak, can have a 2θ angle of 15° to 25°.

[0255] The 2θ of the first peak may be 17° to 23°, and the 2θ of the second peak may be 17° to 23°.

[0256] The 2θ of the first peak may be 19° to 22°, and the 2θ of the second peak may be 19° to 22°.

[0257] The absolute value of the difference between the 2θ of the first peak and the 2θ of the second peak may be 5° or less. The absolute value may be 3° or less. The absolute value may be 2° or less.

[0258] In the blank mask, the AI2 value expressed by the following formula 2 may be 0.9 to 1.1:

[0259] [Formula 2]

[0260]

[0261] Here, XM2 is the intensity value of the first peak, and XQ2 is the intensity value of the second peak.

[0262] The AI2 value may be 0.95 to 1.05. The AI2 value may be 0.97 to 1.03. The AI2 value may be 0.98 to 1.02. In this case, optical distortion that may occur at the interface between the transparent substrate and the phase shift film can be suppressed.

[0263] Crystal properties of light-shielding film

[0264] Compared to other thin films included in the blank mask, the light-shielding film may contain a higher content of metal elements. Consequently, the light-shielding film's dimensional changes in the thickness direction with temperature may be greater than those of other thin films. When this light-shielding film is patterned together with the phase-shift film to form a blind pattern, the shape of the patterned light-shielding film may be deformed by the heat generated by the high-output exposure light source. This can hinder the precise development of fine patterns on semiconductor wafers.

[0265] The embodiment can provide a blank mask capable of suppressing the occurrence of shape deformation of a light-shielding pattern film even in a repeated and long-term exposure process by controlling the crystal characteristics of the light-shielding film and the transparent substrate measured by XRD.

[0266] Figure 8 1 is a schematic diagram showing the X-ray intensity measured by performing normal mode XRD analysis on the light shielding film in a blank mask of an embodiment. Figure 8 An embodiment is described.

[0267] When normal mode XRD analysis is performed on the upper surface of the light-shielding film, the 2θ of the maximum peak of the X-ray intensity measured after reflection can be 15° to 30°. When normal mode XRD analysis is performed on the lower surface of the transparent substrate, the 2θ of the maximum peak of the X-ray intensity measured after reflection can be 15° to 30°.

[0268] In the blank mask, the AI5 value expressed by the following Equation 5 may be 0.5 to 0.97:

[0269] [Formula 5]

[0270]

[0271] Among them, XC1 is the intensity value of the maximum peak of X-ray intensity measured by normal mode XRD analysis on the upper surface of the shading film, and XQ1 is the intensity value of the maximum peak of X-ray intensity measured by normal mode XRD analysis on the lower surface of the transparent substrate.

[0272] The AI5 value may be 0.7 to 0.97. The AI5 value may be 0.5 to 0.95. The AI5 value may be 0.7 to 0.95. The AI5 value may be 0.7 to 0.93. The AI5 value may be 0.9 to 0.93. In this case, the shape deformation of the blind pattern caused by the short wavelength exposure process can be suppressed.

[0273] In the blank mask, the AI6 value expressed by the following Formula 6 may be 1.05 to 1.4:

[0274] [Formula 6]

[0275]

[0276] Among them, the XM4 is the X-ray intensity value when 2θ is 43° when the normal mode XRD analysis is performed on the upper surface of the shading film, and the XQ4 is the X-ray intensity value when 2θ is 43° when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0277] The AI6 value may be 1.06 to 1.4. The AI6 value may be 1.07 to 1.4. The AI6 value may be 1.08 to 1.4. In this case, it is possible to suppress dimensional changes in the thickness direction of the light shielding film due to temperature changes.

[0278] Layer structure of phase shift film

[0279] Figure 9 This is a conceptual diagram showing a blank mask of another embodiment of the present specification. Figure 9 An embodiment is described.

[0280] 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 .

[0281] The phase shift film 20 , the phase difference adjustment layer 21 , and the protective layer 22 may contain transition metals, silicon, oxygen, and nitrogen.

[0282] The phase difference adjustment layer 21 is a layer containing transition metal, silicon, oxygen, and nitrogen uniformly in the range of 5 atomic % in the depth direction of the phase shift film 20. The phase difference adjustment layer 21 can substantially adjust the phase difference and transmittance of light passing through the phase shift film 20.

[0283] 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. Due to this property, the phase shift film 20 effectively cancels out diffracted light generated at the edges of the light-transmitting portion of the photomask, thereby further improving the resolution of the photomask during photolithography.

[0284] Furthermore, the phase difference adjustment layer 21 attenuates exposure light incident from the back side of the transparent substrate 10. Thus, the phase shift film 20 can block transmission of exposure light while canceling diffracted light generated at the edge of the light-transmitting portion.

[0285] The protective layer 22 is formed on the surface of the phase shift film and has a profile in which the oxygen content decreases continuously from the surface toward the depth, while the nitrogen content increases continuously. The protective layer 22 prevents damage to the phase shift film 20 or the patterned phase shift film during photomask etching or cleaning processes, thereby improving the durability of the phase shift film 20. Furthermore, the protective layer 22 prevents oxidation of the phase difference adjustment layer 21 by exposure light during the exposure process.

[0286] Optical properties of phase-shift films measured using ellipsometer

[0287] When the blank mask has a PE1 value of 1.5 eV and a PE2 value of 3.0 eV, the photon energy at a point where the Del_1 value is 0 according to the following equation 7 may be 1.8 eV to 2.14 eV.

[0288] [Formula 7]

[0289]

[0290] In Formula 7, when the light-shielding film is removed from the blank mask and an incident angle of 64.5° is applied to measure the surface of the phase shift film using an ellipsometer, when the phase difference between the P wave and the S wave of the reflected light is less than 180°, 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 greater than 180°, the DPS value is the value obtained by subtracting the phase difference between the P wave and the S wave from 360°.

[0291] The PE value is the photon energy of the incident light within the range of the PE1 value to the PE2 value.

[0292] The resolution of the photomask can be improved by precisely adjusting the optical characteristics of the phase shift film 20 .

[0293] Specifically, the phase difference and transmittance of the phase shift film 20 with respect to exposure light can be adjusted simultaneously. The phase difference and transmittance of the phase shift film 20 can be controlled by adjusting the composition and thickness of the phase shift film. The thickness and transmittance of the phase shift film 20, as well as the thickness and phase difference of the phase shift film 20, have interrelated characteristics. However, there is a trade-off between phase difference and transmittance, making it difficult to achieve desired values ​​simultaneously.

[0294] In the embodiment, by controlling the phase difference distribution of the P-wave and S-wave of the phase shift film measured by ellipsometer, a phase shift film 20 is provided in which the phase difference and transmittance of the phase shift film for light with a wavelength of 200 nm or less are adjusted within a predetermined range in the embodiment and the film is thinner.

[0295] Figure 10 This is a conceptual diagram showing the principle of measuring the phase difference between the P wave and the S wave of the reflected light of the phase shift film using an ellipsometer. Figure 10 An embodiment is described.

[0296] The phase difference Δ between the P-wave P' and S-wave S' of reflected light Lr at a fixed incident angle θ can vary depending on the photon energy of the incident light Li from the spectroscopic ellipsometer. The Del_1 value can be calculated by measuring the phase difference Δ between the P-wave P' and S-wave S' of reflected light Lr at the phase shift film 20 for the photon energy of the incident light Li.

[0297] The distribution of Del_1 values ​​can be adjusted by controlling various factors, such as the elements constituting the phase shift film 20, sputtering process conditions, film thickness, and the incident angle set in the spectroscopic ellipsometry. In particular, the distribution of Del_1 values ​​in the phase shift film 20 can be controlled by, for example, adjusting the intensity of the magnetic field applied to the phase shift film 20 during formation.

[0298] The Del_1 value is measured using a spectroscopic ellipsometer. For example, the NANO-VIEW MG-PRO can be used to measure the phase difference Δ between the P-wave P' and S-wave S' of the reflected light Lr from the phase shift film.

[0299] When measuring the Del_1 value distribution of the phase shift film 20, the measurement is performed after removing the light-shielding film located on the phase shift film 20. If any other thin films are located between the phase shift film 20 and the light-shielding film, these thin films are removed. Etching is a method for removing the light-shielding film and other thin films, but is not limited to this method. Because removing other thin films located on the phase shift film without damaging the phase shift film 20 is technically difficult, damage to the phase shift film of less than 1 nm in the thickness direction during the etching process is permitted.

[0300] In the blank mask, when the PE1 value is 1.5 eV and the PE2 value is 3.0 eV, the photon energy at the point where the Del_1 value is 0 can be 1.8 eV to 2.14 eV. The photon energy can be 1.85 eV to 2.1 eV. The photon energy can be 1.9 eV to 2.05 eV. In this case, the phase shift film 20 can have the desired transmittance and phase difference for short-wavelength exposure light, while having a smaller thickness.

[0301] In the blank mask, when the PE1 value is 3 eV and the PE2 value is 5 eV, the photon energy at the point where the Del_1 value is 0 can be 3.8 to 4.64 eV.

[0302] When incident light Li with high photon energy is irradiated onto the measurement object, the incident light Li is reflected at the surface of the phase shift film 20 or at a location shallow from the surface 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 shift film 20 with incident light Li having high photon energy, the optical properties of the surface portion of the phase shift film 20, particularly the optical properties of the protective layer 22, can be confirmed.

[0303] The protective layer 22 is located on the phase difference adjustment layer 21 and plays the role of protecting the phase difference adjustment layer 21 from exposure light, cleaning solutions, etc. The thicker the protective layer 22 is, the denser the structure of the protective layer 22 is, and the more stably the protective layer 22 can protect the phase difference adjustment layer 21. However, when the protective layer 22 is formed only by considering the stable protection of the phase difference adjustment layer 21, the overall optical characteristics of the phase shift film 20 may change significantly due to the influence of the formation of the protective layer 22. In this case, the phase shift film 20 may have characteristics that deviate from the originally designed optical characteristics. The embodiment can provide a phase shift film 20 in which the phase difference adjustment layer 21 is stably protected and the optical characteristics do not change significantly compared to before the protective layer 22 is formed by controlling the P-wave and S-wave distribution characteristics of the phase shift film 20.

[0304] The photon energy distribution at the point where the Del_1 value is 0 (when the PE1 value is 3 eV and the PE2 value 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_1 value can be controlled by controlling the heat treatment temperature and time during the annealing process after UV treatment of the surface of the formed phase difference adjustment layer 21.

[0305] In the blank mask 100, when the PE1 value is 3 eV and the PE2 value is 5 eV, the photon energy at the point where the Del_1 value is 0 can be 3.8 eV or greater. The photon energy can be 4 eV or greater. The photon energy can be 4.2 eV or greater. The photon energy can be 4.3 eV or greater. The photon energy can be 4.64 eV or less. The photon energy can be 4.62 eV or less. The photon energy can be 4.6 eV or less. 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.

[0306] In the blank mask 100 , when the PE1 value is 1.5 eV and the PE2 value is the minimum value of the photon energy of the incident light at the point where the Del_1 value is 0, the average value of Del_1 may be 78° / eV to 98° / eV.

[0307] When the photon energy of incident light is within a range of 1.5 eV or greater and not more than the minimum value of the photon energy of incident light at a point where the Del_1 value is 0, the incident light has a relatively long wavelength. This incident light penetrates relatively deeply into the phase shift film and is then reflected. Therefore, the average value of Del_1 measured when the photon energy is within this range reflects the optical characteristics of the phase difference adjustment layer 21 in the phase shift film 20.

[0308] In the blank mask 100, when the PE1 value is 1.5 eV and the PE2 value is the minimum value among the photon energies of the incident light at the point where the Del_1 value is 0, the average value of the Del_1 value 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 have a lower thickness while maintaining the target phase difference and transmittance for short-wavelength light.

[0309] In the blank mask 100 , when the PE1 value is the minimum value among the photon energies of the incident light at the point where the Del_1 value is 0 and the PE2 value is the maximum value among the photon energies of the incident light at the point where the Del_1 value is 0, the average value of Del_1 may be −65 to −55° / eV.

[0310] When the photon energy of the incident light has a value within a range from a minimum value among the photon energies of the incident light at a point where the Del_1 value is 0 to a maximum value among the photon energies of the incident light at a point where the Del_1 value is 0, the average value of the Del_1 value measured under such conditions reflects the optical characteristics of the portion near the interface between the phase difference adjustment layer 21 and the protective layer 22, etc.

[0311] In the blank mask 100, when the PE1 value is the minimum value among the photon energies of the incident light at the point where the Del_1 value is 0, and the PE2 value is the maximum value among the photon energies of the incident light at the point where the Del_1 value is 0, the average value of Del_1 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 interface formed between the phase difference adjustment layer 21 and the protective film 22 from significantly affecting the optical characteristics of the entire phase shift film.

[0312] In the blank mask 100 , when the PE1 value is the maximum value among the photon energies of the incident light at the point where the Del_1 value is 0 and the PE2 value is 5.0 eV, the average value of Del_1 may be 60 to 120° / eV.

[0313] The average value of Del_1 measured by setting the PE1 value to the maximum value among the photon energies of incident light at a point where the Del_1 value is 0 and the PE2 value to 5.0 eV reflects the optical characteristics and the like of the protective layer 22 .

[0314] In the blank mask 100, when the PE1 value is the maximum value among the photon energies of incident light at a point where the Del_1 value is 0, and the PE2 value is 5.0 eV, the average Del_1 value can be 60° / eV to 120° / eV. The average value can be 70 to 110° / eV. The average value can be 80 to 105° / eV. In this case, the effect of the protective layer 22 on the optical characteristics of the entire phase shift film 20 can be reduced, and the phase shift film 20 can have stable durability.

[0315] In the blank mask 100, when the PE1 value measured after forming the protective layer 22 is 1.5eV and the PE2 value is 3.0eV, the absolute value of the difference between the photon energy value of the incident light at the point where the Del_1 value is 0 and the photon energy value of the incident light at the point where the Del_1 value is 0 measured before forming the protective layer 22 can be 0.001 to 0.2eV.

[0316] During the process of forming 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 atmospheric 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. Such changes may cause the optical properties of the phase difference adjustment layer itself to change. This may cause the phase shift film to have properties that deviate from the intended optical properties in the embodiment. The embodiment can provide a blank mask capable of presenting higher resolution by controlling the difference in the optical properties of the phase difference adjustment layer itself before and after the protective layer is formed.

[0317] In the blank mask 100, when the PE1 value measured after forming the protective layer 22 is 1.5 eV and the PE2 value is 3.0 eV, the absolute value of the difference between the photon energy value of the incident light at the point where the Del_1 value is 0 and the photon energy value of the incident light at the point where the Del_1 value is 0 measured before forming 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 variation of the phase difference adjustment layer 21 itself caused by the formation of the protective layer 22.

[0318] In the blank mask 100, when the PE1 value measured after forming the protective layer 22 is 3.0 eV and the PE2 value is 5.0 eV, the absolute value of the difference between the photon energy of the incident light at the point where the Del_1 value is 0 and the photon energy of the incident light at the point where the Del_1 value is 0 measured before forming 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 impact of the optical properties of the protective layer 22 itself on the optical properties of the entire phase shift film 20.

[0319] In the blank mask 100 , when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of Del_1 may be 105° / eV to 300° / eV.

[0320] In an embodiment, the maximum value of Del_1 when the PE1 value of the blank mask 100 is adjusted to 1.5 eV and the PE2 value is 5.0 eV can be used to ensure the phase shift film 20 has stable durability, while the variation of the optical characteristics of the entire phase shift film 20 caused by the formation of the protective layer 22 can be adjusted within a certain range.

[0321] In the blank mask 100, when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of Del_1 can be 105 to 300° / eV. This maximum value can be 120 to 200 eV, or 140 to 160 eV. In this case, the change in the optical properties of the entire phase shift film 20 caused by the formation of the protective layer 22 can be reduced, while the phase shift film 20 can have excellent light resistance and chemical resistance.

[0322] In the blank mask 100 , when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the photon energy at the point where Del_1 reaches the maximum value may be greater than 4.5 eV.

[0323] When the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of Del_1 reflects the optical characteristics of the protective layer 22. In this embodiment, by adjusting the photon energy value at the point of the maximum value of Del_1, the protective layer 22 can have stable durability while reducing the impact of the protective layer 22 on the optical characteristics of the entire phase shift film 20.

[0324] In the blank mask 100, when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the photon energy value at the point where Del_1 reaches its maximum value can be 4.5 eV or greater. The photon energy value at the point where Del_1 reaches its maximum value can be 4.55 eV or greater. The photon energy value at the point where Del_1 reaches its maximum value can be 5 eV or less. The photon energy value at the point where Del_1 reaches its maximum value can be 4.8 eV or less. In this case, the phase shift film 20 can exhibit desired optical properties for short wavelengths while suppressing fluctuations in optical properties caused by exposure and cleaning processes.

[0325] In the blank mask 100 , when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the value obtained by subtracting the minimum value of Del_1 from the maximum value of Del_1 may be 60 to 260 eV.

[0326] The inventors of the embodiment have found through experiments that when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of Del_1 reflects the optical properties of the protective layer 22 of the phase shift film 20 , and the minimum value of Del_1 reflects the optical properties of the upper portion of the phase difference adjustment layer 21 .

[0327] Before and after the protective layer is formed, when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum and minimum values ​​of Del_1 may vary. By controlling the value (minus the minimum value of Del_1) from the maximum value of Del_1 within a certain range, the optical properties of the entire phase shift film 20 before and after the formation of the protective layer 22 can vary within an acceptable range.

[0328] In a blank mask, when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the value obtained by subtracting the minimum value of Del_1 from the maximum value of Del_1 can be 60 to 260 eV. The value obtained by subtracting the minimum value of Del_1 from the maximum value of Del_1 can be 80 to 240 eV. The value obtained by subtracting the minimum value of Del_1 from the maximum value of Del_1 can be 90 to 230 eV. In this case, the variation in the optical properties of the entire phase shift film before and after the formation of the protective layer can be controlled within a certain range.

[0329] Composition of phase shift film

[0330] The phase shift film 20 may include a transition metal, silicon, oxygen, and nitrogen. The transition metal may be one or more elements selected from molybdenum (Mo), tantalum (Ta), zirconium (Zr), etc., but is not limited thereto. For example, the transition metal may be molybdenum.

[0331] The phase-shift film 20 may contain 1 to 10 atomic percent of a transition metal. The phase-shift film 20 may contain 2 to 7 atomic percent of a transition metal. The phase-shift film 20 may contain 15 to 60 atomic percent of silicon. The phase-shift film 20 may contain 25 to 50 atomic percent of silicon. The phase-shift film 20 may contain 30 to 60 atomic percent of nitrogen. The phase-shift film 20 may contain 35 to 55 atomic percent of nitrogen. The phase-shift film 20 may contain 5 to 35 atomic percent of oxygen. The phase-shift film 20 may contain 10 to 25 atomic percent of oxygen. In this case, the phase-shift film 20 may have optical properties suitable for photolithography processes using short-wavelength exposure light, specifically, light having a wavelength of 200 nm or less.

[0332] The phase shift film 20 may further contain other elements besides the elements mentioned above. For example, the phase shift film 20 may contain argon (Ar), helium (He), or the like.

[0333] In the phase shift film 20 , the content of each element may be different in the thickness direction.

[0334] The content distribution of each element formed in the thickness direction of the phase difference adjustment 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 using a K-alpha model from Thermo Scientific, for example.

[0335] The contents of elements such as transition metal, silicon, oxygen, and nitrogen in the phase difference adjustment layer 21 and the protective layer 22 may be different from each other.

[0336] The phase difference adjustment layer 21 may contain 3 to 10 atomic % of a transition metal. The phase difference adjustment layer 21 may contain 4 to 8 atomic % of a transition metal. The phase difference adjustment layer 21 may contain 20 to 50 atomic % of silicon. The phase difference adjustment layer 21 may contain 30 to 40 atomic % of silicon. The phase difference adjustment layer 21 may contain 2 to 10 atomic % of oxygen. The phase difference adjustment layer 21 may contain 3 to 8 atomic % of oxygen. The phase difference adjustment layer 21 may contain 40 to 60 atomic % of nitrogen. The phase difference adjustment layer 21 may contain 45 to 55 atomic % of nitrogen. In this case, when short-wavelength exposure light, specifically, light with a wavelength of 200 nm or less, is applied as the exposure light, the blank mask may have excellent pattern resolution.

[0337] The more oxygen the protective layer 22 contains, the more stably it protects the phase difference adjustment layer 21 from exposure light and cleaning solutions. However, such a protective layer 22 may significantly affect fluctuations in the optical properties of the entire phase shift film 20 before and after its formation. Therefore, by controlling the distribution of oxygen and nitrogen content in the protective layer 22, the phase shift film 20 can be made to have sufficient light resistance and chemical resistance while also maintaining the desired optical properties in the embodiments.

[0338] 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 deterioration of the phase difference adjustment layer 21.

[0339] The protective layer 22 may include a region having a ratio of nitrogen content (atomic %) to oxygen content (atomic %) of 1 or greater in the thickness direction. The thickness of the region may be 40 to 60% of the total thickness of the protective layer 22. The thickness of the region may be 45 to 55% of the total thickness of the protective layer 22. In this case, changes in the optical characteristics of the phase shift film 20 caused by the formation of the protective layer 22 can be effectively suppressed.

[0340] The protective layer 22 may include a region having a ratio of nitrogen content (atomic %) to oxygen content (atomic %) of 0.4 to 2 in the thickness direction, and the thickness of the region may be 30 to 80% of the total thickness of the protective layer 22. 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 producing a photomask having sufficient durability and excellent resolution can be provided.

[0341] The thickness of the region where the ratio of the nitrogen content (atomic %) to the oxygen content (atomic %) in the thickness direction is adjusted can be measured by measuring the depth profile. 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 profile.

[0342] Optical properties of phase shift films and thickness of each layer

[0343] The phase shift film 20 can have a phase difference of 160 to 200° for light with a wavelength of 200 nm or less. 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 a wavelength of 200 nm or less. The phase shift film 20 can have a phase difference of 170 to 190° for ArF light. The phase shift film 20 can have a transmittance of 3 to 10% for light with a wavelength of 200 nm or less. The phase shift film 20 can have a transmittance of 3 to 10% for ArF light. The phase shift film 20 can have a transmittance of 4 to 8% for light with a wavelength of 200 nm or less. The phase shift film 20 can have a transmittance of 4 to 8% for ArF light. In this case, a photomask including the phase shift film 20 can form finer patterns on a wafer during an exposure process using short-wavelength exposure light.

[0344] The refractive index of the protective layer 22 for light with a wavelength of 200 nm or less may be 1.3 to 2. The refractive index of the protective layer 22 for ArF light may be 1.3 to 2. The refractive index of the protective layer 22 for light with a wavelength of 200 nm or less may be 1.4 to 1.8. The refractive index of the protective layer 22 for ArF light may be 1.4 to 1.8. The extinction coefficient of the protective layer 22 for light with a wavelength of 200 nm or less may be 0.2 to 0.4. The extinction coefficient of the protective layer 22 for ArF light may be 0.2 to 0.4. The extinction coefficient of the protective layer 22 for light with a wavelength of 200 nm or less may be 0.25 to 0.35. The extinction coefficient of the protective layer 22 for ArF light may be 0.25 to 0.35. In this case, changes in the optical characteristics of the phase shift film 20 caused by the formation of the protective layer 22 can be minimized.

[0345] The refractive index of the phase difference adjustment layer 21 for light with a wavelength of 200 nm or less may be 2 to 4. The refractive index of the phase difference adjustment layer 21 for ArF light may be 2 to 4. The refractive index of the phase difference adjustment layer 21 for light with a wavelength of 200 nm or less may be 2.5 to 3.5. The refractive index of the phase difference adjustment layer 21 for ArF light may be 2.5 to 3.5. The extinction coefficient of the phase difference adjustment layer 21 for light with a wavelength of 200 nm or less may be 0.3 to 0.7. The extinction coefficient of the phase difference adjustment layer 21 for ArF light may be 0.3 to 0.7. The extinction coefficient of the phase difference adjustment layer 21 for light with a wavelength of 200 nm or less may be 0.4 to 0.6. The extinction coefficient of the phase difference adjustment layer 21 for ArF light may be 0.4 to 0.6. In this case, the resolution of the photomask including the phase shift film 20 can be further improved.

[0346] The optical properties of the phase shift film 20, the protective layer 22, and the phase difference adjustment layer 21 can be measured by using a spectroscopic ellipsometer. For example, the optical properties can be measured by using an MG-PRO device manufactured by NANO-VIEW.

[0347] The ratio of the thickness of the protective layer 22 to the thickness of the entire phase shift film 20 may be 0.04 to 0.09. The ratio may be 0.05 to 0.08. In this case, the protective layer 22 can stably protect the phase difference adjustment layer 21.

[0348] The thickness of the protective layer 22 can be Above and The thickness of the protective layer 22 can be Above and In this case, it is possible to provide a phase shift film 20 that effectively reduces the degree of variation in the optical characteristics of the entire phase shift film and exhibits stable optical characteristics even during a long exposure process and a cleaning process.

[0349] The thickness of the phase shift film 20 and each layer constituting the phase shift film 20 can be measured by a transmission electron microscope (TEM) image of a cross section of the phase shift film 20 .

[0350] Layer structure, composition, and optical properties of light-shielding films

[0351] The light shielding film 30 may be provided on the phase shift film 20. When the phase shift film 20 is etched according to a pre-designed pattern shape, the light shielding film 30 may be used as an etching mask for the phase shift film 20. In addition, the light shielding film 30 can block exposure light incident from the back side of the transparent substrate 10.

[0352] The light shielding film 30 may have a single-layer structure. The light shielding film 30 may also have a multi-layer structure with two or more layers. During the sputtering process of the light shielding film 30, the atmosphere gas composition and flow rate may be different for each layer of the light shielding film, thereby forming a light shielding film 30 having a multi-layer structure. During the sputtering process of the light shielding film 30, different sputtering targets may be used for each layer of the light shielding film, thereby forming a light shielding film 30 having a multi-layer structure.

[0353] 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 light shielding film having a multilayer structure, the composition of each layer in the light shielding film 30 may vary.

[0354] The light-shielding film 30 may contain 30 to 70 atomic percent of chromium. The light-shielding film 30 may contain 47 to 57 atomic percent of chromium. The light-shielding film 30 may contain 5 to 30 atomic percent of carbon. The light-shielding film 30 may contain 7 to 25 atomic percent of carbon. The light-shielding film 30 may contain 3 to 30 atomic percent of nitrogen. The light-shielding film 30 may contain 5 to 25 atomic percent of nitrogen. The light-shielding film 30 may contain 20 to 55 atomic percent of oxygen. The light-shielding film 30 may contain 25 to 40 atomic percent of oxygen. In this case, the light-shielding film 30 can have sufficient extinction performance.

[0355] The multilayer film (not shown) includes a phase shift 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.

[0356] The optical density of the multilayer film for light with a wavelength of 200 nm or less can be 3 or greater. The optical density of the multilayer film for ArF light can be 3 or greater. The optical density of the multilayer film for light with a wavelength of 200 nm or less can be 3.5 or greater. The optical density of the multilayer film for ArF light can be 3.5 or greater. In this case, the multilayer film can have excellent light-blocking properties.

[0357] Preparation method of phase shift film

[0358] The phase difference adjustment layer in the phase shift film of the embodiment can be prepared by forming a thin film on a transparent substrate by sputtering.

[0359] In the sputtering process, a direct current (DC) power source or a radio frequency (RF) power source may be used.

[0360] The target material and sputtering gas can be selected by considering the composition of the phase shift film to be formed.

[0361] In the case of sputtering targets, a single target containing a transition metal and silicon, or a target containing a transition metal and a target containing silicon can be used separately. When a single target is used as a sputtering target, the transition metal content can be 30% or less relative to the sum of the transition metal and silicon contents of the target. The transition metal content can be 20% or less relative to the sum of the transition metal and silicon contents of the target. The transition metal content can be 10% or less relative to the sum of the transition metal and silicon contents of the target. The transition metal content can be 2% or more relative to the sum of the transition metal and silicon contents of the target. In this case, the use of such a target helps form a phase shift film with desired optical properties during the sputtering process.

[0362] The sputtering gas may include, but is not limited to, CH₄ as a carbon-containing gas, O₂ as an oxygen-containing gas, or N₂ as a nitrogen-containing gas. An inert gas may be added to the sputtering gas. Examples of inert gases include, but are not limited to, Ar and He. The type and content of the inert gas can be used to adjust the crystal properties of the phase shift film formed during sputtering. Each gas in the sputtering gas may be introduced separately into the chamber. Alternatively, the various gases may be mixed and then the resulting mixed gas introduced as the sputtering gas.

[0363] To ensure that the phase-shift film has more uniform crystal properties in the in-plane direction, a magnet can be installed in the chamber. Specifically, the magnet can be placed on the back side of the sputtering target and rotated at a speed sufficient to maintain the plasma distribution across the entire target surface. The magnet can be rotated at a speed of 50 to 200 rpm.

[0364] The rotation speed of the magnet can be fixed at a constant speed during sputtering. The rotation speed of the magnet can be varied during sputtering. During sputtering, the rotation speed of the magnet can be increased from an initial rotation speed to a constant speed.

[0365] The rotation speed of the magnet can be increased from the initial rotation speed during sputtering by 5 to 20 rpm per minute. The rotation speed of the magnet can be increased from the initial rotation speed during sputtering by 7 to 15 rpm per minute. In this case, the desired film quality characteristics in the thickness direction of the phase shift film can be easily controlled.

[0366] Adjusting the magnetic field of the magnet adjusts the density of the plasma formed in the chamber, thereby controlling the crystal properties of the resulting phase shift film. The magnetic field of the magnet applied during the sputtering process can be 25 to 60 mT. Alternatively, the magnetic field can be 30 to 50 mT. In this case, the resulting phase shift film 20 can have crystal properties more similar to those of the transparent substrate.

[0367] During the sputtering process, the distance between the target and substrate, known as the T / S distance, and the angle between the substrate and target can be adjusted. The T / S distance can be 240 to 260 mm. The angle between the substrate and target can be 20 to 30 degrees. This allows for stable control of the phase-shift film deposition rate, suppressing excessive buildup of internal stress in the phase-shift film.

[0368] During the sputtering process, the rotation speed of the substrate having the surface to be film-formed can be adjusted. The substrate rotation speed can be between 2 and 20 RPM. Alternatively, the substrate rotation speed can be between 5 and 15 RPM. When the substrate rotation speed is adjusted within this range, the uniformity of the in-plane optical properties of the formed phase shift film is further improved, while also ensuring stable durability.

[0369] Furthermore, when forming the phase difference adjustment layer, the power intensity applied to the sputtering target can be adjusted. By supplying power to the sputtering target, a discharge region comprising a plasma atmosphere can be formed within the chamber. By adjusting the power intensity while also adjusting the magnetic field and rotational speed of the magnet, the crystal properties of the resulting phase shift film can be adjusted. The power intensity applied to the sputtering target can range from 1 to 3 kW, 1.5 to 2.5 kW, or 1.8 to 2.2 kW. In this manner, the temperature-dependent thermal fluctuations of the phase shift film in the thickness direction can be controlled within a certain range.

[0370] A spectroscopic ellipsometer can be installed in the sputtering equipment. This allows the film formation time to be controlled while monitoring the optical properties of the formed phase difference adjustment layer 21. Specifically, after adjusting the angle between the incident light and the surface of the formed phase difference adjustment layer, the Del_1 value of the formed phase difference adjustment layer 21 can be monitored in real time during the film formation process. The film formation process is continued until the Del_1 value falls within the pre-set range in the embodiment, thereby ensuring that the phase shift film has the desired optical properties.

[0371] By varying the photon energy of the incident light into the spectroscopic ellipsometer, the phase difference between the P-wave and S-wave of the reflected light can be measured, thereby determining the optical properties of each layer of the phase shift film. Specifically, when the photon energy of the incident light is set to a relatively low level, the incident light has a long wavelength, enabling measurement of the optical properties of the lower layer of the phase shift film being measured. When the photon energy of the incident light is set to a relatively high level, the incident light has a short wavelength, enabling measurement of the optical properties of the upper layer of the phase shift film being measured.

[0372] Ultraviolet (UV) light can be irradiated to the surface of the phase difference adjustment layer immediately after the sputtering process is completed. During the sputtering process, the Si of the silicon dioxide (SiO2) matrix constituting the transparent substrate can be replaced by a transition metal, and the oxygen (O) of the SiO2 matrix is ​​replaced by nitrogen (N). When the sputtering process is continued, due to exceeding the solubility limit (Solubility Limit), the transition metal may be located in the interstitial site (Interstitial site) instead of replacing the Si in the SiO2 matrix. In this case, the transition metal can form a mixture with elements such as Si, O, and N. The mixture can be in a homogeneous state or an inhomogeneous state.

[0373] When a heterogeneous mixture forms on the surface of the phase adjustment layer, the short-wavelength exposure light during the exposure process may cause haze defects on the surface of the phase adjustment layer. When sulfuric acid is used as a cleaning solution to remove these haze defects, sulfur ions may remain on the surface of the phase adjustment layer after cleaning. These residual sulfur ions may continue to receive strong energy from the exposure light during the wafer exposure process. The high-energy sulfur ions may react with the heterogeneous mixture, causing growth defects on the surface of the phase adjustment layer. In an embodiment, by irradiating the phase adjustment layer surface with UV light of a controlled wavelength, the transition metal and nitrogen content in the mixture on the surface of the phase adjustment layer is homogenized along the in-plane direction, thereby further improving the light resistance and chemical resistance of the phase adjustment layer.

[0374] This can be achieved by using a 2 to 10 mW / cm 2 The surface of the phase difference adjusting layer is irradiated with light having a wavelength of 200 nm or less for 5 to 20 minutes from a light source having a high power to perform surface treatment on the phase difference adjusting layer.

[0375] The heat treatment may be performed together with the UV light irradiation process or separately on the phase difference adjustment layer 21. The UV light irradiation process and the heat treatment may be performed by heat generated during UV irradiation or separately.

[0376] The phase adjustment layer 21 formed by the sputtering process may have internal stress. Depending on the sputtering conditions, the internal stress may be compressive or tensile. The internal stress of the phase adjustment layer may cause the substrate to bend, ultimately resulting in a decrease in the resolution of the photomask using the phase adjustment layer. In this embodiment, the phase adjustment layer is heat-treated to reduce the substrate's bending.

[0377] The protective layer can be formed by a heat treatment process after the phase difference adjustment layer is formed. During the 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 a chamber. During the heat treatment process, the protective layer can be formed by reacting the surface of the phase difference adjustment layer with the atmospheric gas. However, the method for preparing the protective layer is not limited thereto.

[0378] The heat treatment process may include a temperature increasing step, a temperature maintaining step, a temperature decreasing step, and a protective layer forming step. The heat treatment process may be performed by placing a blank mask having the phase difference adjustment layer 21 formed on its surface in a chamber and then heating it with a lamp.

[0379] In the temperature raising step, the temperature of the atmosphere in the heat treatment chamber may be raised to a set temperature of 150 to 500°C.

[0380] In the temperature maintaining step, the atmospheric temperature in the chamber may be maintained at the set temperature, and the pressure in the chamber may be adjusted to 0.1 to 2.0 Pa. The temperature maintaining step may be performed for 5 to 60 minutes.

[0381] In the cooling step, the temperature in the chamber can be lowered from the set temperature to room temperature.

[0382] The protective layer forming step is a step of forming a protective layer on the surface of the phase shift film by introducing an atmospheric gas containing a reactive gas into the chamber after the cooling step. The reactive gas may contain oxygen (O2). The gas introduced into the chamber in the protective layer forming step may contain any one selected from nitrogen (N2), argon (Ar) and helium (He). Specifically, in the protective layer forming step, 0.3 to 2.5 standard liters per minute (SLM) of O2 gas may be introduced into the chamber. 0.5 to 2 SLM of the O2 gas may be introduced into the chamber. The protective layer forming step may be performed for 10 to 60 minutes. The protective layer forming step 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 the change in the optical properties of the entire phase shift film caused by the formation of the protective layer.

[0383] Preparation method of light-shielding film

[0384] The light-shielding film of the embodiment may be formed in contact with the phase shift film, or in contact with another thin film located on the phase shift film.

[0385] The light-shielding film may include a lower layer and an upper layer located on the lower layer.

[0386] A DC power source or an RF power source may be used in the sputtering process.

[0387] The target material and sputtering gas used in the sputtering process of the light-shielding film can be selected by considering the composition of the light-shielding film. When the light-shielding film has two or more layers, the type and flow rate of the sputtering gas used for sputtering each layer can be different.

[0388] In the case of a sputtering target, a single target containing chromium may be used, or two or more targets including the single target containing chromium may be used. The target may contain 90 atomic % or more of chromium, 95 atomic % or more of chromium, or 99 atomic % or more of chromium.

[0389] The type and flow rate of the sputtering gas can be adjusted by taking into consideration the composition of elements constituting each layer of the light-shielding film, the crystal properties and optical properties of the light-shielding film, and the like.

[0390] The sputtering gas may include reactive gases and inert gases. The optical and crystal properties of the resulting light-shielding film can be controlled by adjusting the type and content of the reactive gas in the sputtering gas. Reactive gases may include CO₂, O₂, N₂, and NO₂. The reactive gas may also include other gases besides those listed above.

[0391] The crystal properties of the light-shielding film to be formed can be controlled by adjusting the type and content of the inert gas in the sputtering gas. The inert gas may include Ar, He, and Ne. The inert gas may also include other gases besides the gases listed above.

[0392] When forming the lower layer of the light shielding film, a sputtering gas containing Ar, N2, He, and CO2 may be injected into the chamber. Specifically, a sputtering gas having a total flow rate of CO2 and N2 of 40% or more relative to the total flow rate of the sputtering gas may be injected into the chamber.

[0393] When forming the upper layer of the light shielding film, a sputtering gas containing Ar and N2 may be injected into the chamber. Specifically, a sputtering gas having an N2 flow rate of 30% or more relative to the total flow rate of the sputtering gas may be injected into the chamber.

[0394] In this case, the light-shielding film can have the crystalline properties desired in the embodiment.

[0395] The various gases constituting the sputtering gas can be mixed and injected into the sputtering chamber. The various gases constituting the sputtering gas can be injected separately according to their types through different inlets in the sputtering chamber.

[0396] A magnet can be placed in the chamber to control the uniformity of the crystal properties and in-plane optical properties of the light-shielding film to be formed. Specifically, the plasma can be relatively evenly distributed across the entire surface of the target by placing the magnet on the back side of the sputtering target and rotating the magnet at a speed within the predetermined range in the embodiment. When forming each layer of the light-shielding film, the magnet can be rotated at a speed of 50 to 200 rpm.

[0397] During the sputtering process, the distance between the target and substrate (T / S distance) and the angle between the substrate and target can be adjusted. The T / S distance during each layer of the light-shielding film can be 240 to 300 mm. The angle between the substrate and target can be 20 to 30 degrees. This allows for stable film deposition speed, suppressing excessive internal stress buildup in the film.

[0398] During the sputtering process, the rotation speed of the substrate having the film-forming target surface can be adjusted. The rotation speed of the substrate can be 2 to 50 RPM. The rotation speed of the substrate can be 10 to 40 RPM. When the rotation speed of the substrate is adjusted within the above range, the light-shielding film can exhibit reduced dimensional change characteristics during a long exposure process.

[0399] Furthermore, when forming a light-shielding film, the power intensity applied to the sputtering target can be adjusted. By supplying power to the target within the sputtering chamber, a discharge region containing a plasma atmosphere can be formed within the chamber. Adjusting the power intensity can be used to control the plasma atmosphere within the chamber in conjunction with the magnets. This allows for the adjustment of the crystal properties of the light-shielding film formed during the sputtering process.

[0400] 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, the resolution of the photomask caused by thermal fluctuations of the light-shielding film can be effectively prevented from decreasing.

[0401] A spectroscopic ellipsometer can be installed in the sputtering equipment. This allows the optical properties of the formed light-shielding film to be monitored while controlling the film formation time. The method of installing a spectroscopic ellipsometer in the sputtering equipment and measuring the optical properties of the light-shielding film during film formation is repeated with the phase shift film formation and is therefore omitted.

[0402] When forming the lower layer of the light-shielding film, sputtering may be performed until the photon energy at the point where the phase difference between the P wave and the S wave of the reflected light measured by a spectroscopic ellipsometer is 140° is 1.6 to 2.2 eV. When forming the lower layer of the light-shielding film, sputtering may be performed until the photon energy at the point where the phase difference between the P wave and the S wave of the reflected light measured by a spectroscopic ellipsometer is 140° is 1.8 to 2.0 eV.

[0403] When forming the upper layer of the light-shielding film, sputtering may be performed until the photon energy at the point where the phase difference between the P wave and the S wave of the reflected light measured by spectroscopic ellipsometry is 140° is 1.7 to 3.2 eV. When forming the upper layer of the light-shielding film 30, sputtering may be performed until the photon energy at the point where the phase difference between the P wave and the S wave of the reflected light measured by spectroscopic ellipsometry is 140° is 2.5 to 3.0 eV.

[0404] In this case, the formed light-shielding film is included in the blind pattern of the photomask, thereby being able to effectively block the exposure light.

[0405] photomask

[0406] Figure 11 is a cross-sectional view showing a photomask of another embodiment. Figure 11 An embodiment is described.

[0407] A photomask 200 according to another embodiment of the present disclosure includes: a transparent substrate 10 ; a phase shift film 20 disposed on the transparent substrate 10 ; and a light shielding film 30 disposed on at least a portion of the phase shift film 20 .

[0408] The photomask 200 was analyzed using normal mode XRD. In the normal mode XRD analysis, the maximum peak of the X-ray intensity measured after reflection on the phase shift film 20 side had a 2θ value of 15° to 30°.

[0409] In the normal mode XRD analysis, 2θ of the maximum peak of the X-ray intensity measured after reflection on the transparent substrate 10 side is 15° to 30°.

[0410] The AI1 value expressed by the following formula 1 is 0.9 to 1.1:

[0411] [Formula 1]

[0412]

[0413] In Formula 1, XM1 is the maximum value of X-ray intensity measured when the normal mode XRD analysis is performed on the phase shift film.

[0414] The XQ1 is a maximum value of X-ray intensity measured when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.

[0415] The photomask can be made of the blank mask described above. Specifically, the photomask can be manufactured by patterning the phase shift film and the light shielding film of the blank mask.

[0416] The description of the thermal fluctuation characteristics, optical characteristics, etc. of the phase shift film and the light shielding film overlaps with the above description of the thermal fluctuation characteristics and optical characteristics of the phase shift film and the light shielding film, and thus is omitted.

[0417] A photomask according to another embodiment of the present disclosure includes: a transparent substrate; a phase shift film disposed on the transparent substrate; and a light shielding film disposed on the phase shift film.

[0418] In the photomask, 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 expressed by the following equation 8 is 4.0 to 5.0 eV:

[0419] [Formula 8]

[0420]

[0421] In Formula 8, when the light-shielding film is removed from the photomask and an incident angle of 64.5° is applied, and the surface of the phase shift film is measured using an ellipsometer, when the phase difference between the P wave and the S wave of the reflected light is less than 180°, 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 greater than 180°, the pDPS value is the value obtained by subtracting the phase difference between the P wave and the S wave from 360°.

[0422] The PE value is the photon energy of the incident light within the range from PE1 to PE2.

[0423] The photomask can be made of the blank mask described above. Specifically, the photomask can be manufactured by patterning the phase shift film and the light shielding film of the blank mask.

[0424] The description of the optical characteristics of the phase shift film and the light shielding film overlaps with the above description of the optical characteristics of the phase shift film and the light shielding film and is therefore omitted.

[0425] Hereinafter, specific embodiments will be described in more detail.

[0426] Preparation example: Formation of phase shift film and light shielding film

[0427] Example 1: A transparent quartz substrate measuring 6 inches long, 6 inches wide, and 0.25 inches thick was placed in the chamber of a DC sputtering apparatus. A target composed of molybdenum and silicon at an atomic ratio of 1:9 was placed in the chamber, with a T / S distance of 255 mm and a 25-degree angle between the substrate and the target. A magnet with a magnetic field of 40 mT was placed behind the target.

[0428] Then, a sputtering gas mixture of Ar:N2:He = 10:52:38 was introduced into the chamber at a sputtering power of 2.05 kW, and a rotating magnet was used to perform the sputtering process. The magnet's rotational speed was increased from an initial 100 rpm at a rate of 11 rpm per minute to a maximum of 155 rpm. The thin film formation area was limited to a 132 mm long and 132 mm wide region on the transparent substrate surface. The sputtering process was continued until the photon energy at the point where the Del_1 value, measured using spectroscopic ellipsometry, reached 2.0 eV at an incident angle of 64.5° and a value of 0 was reached, as measured using spectroscopic ellipsometry.

[0429] After the sputtering is completed, the phase shift film surface of the blank mask is exposed using 172nm wavelength excimer UV light. At this time, the output of the UV light is 3mW / cm per minute. 2 Rising to a maximum of 9mW / cm 2 , at 9mW / cm 2 Maintain power for 4 minutes.

[0430] The blank mask was then introduced into a heat treatment chamber and annealed at 1 Pa before being cooled naturally. The temperature during the annealing process was increased from room temperature at 50°C per minute to a maximum of 400°C and maintained at the maximum temperature for approximately 30 minutes. After the cooling process was complete, O2 gas was introduced into the heat treatment chamber at a rate of 1 SLM for 30 minutes. The O2 supply temperature was approximately 300°C.

[0431] A light-shielding film sputtering process was performed on the surface of the formed phase-shift film. Specifically, a chromium target and a transparent substrate with a phase-shift film formed thereon were placed in a sputtering chamber, with a T / S distance of 255 mm and a 25-degree angle between the substrate and the target. A magnet with a 40 mT magnetic field was placed on the back of the target.

[0432] A sputtering gas with a flow rate ratio of Ar:N2:He:CO2 = 19:11:34:37 ​​was injected into the chamber. Then, while the magnet was rotating at a sputtering power of 1.35 kW, sputtering was continued until the photon energy at the point where the phase difference between the P-wave and S-wave reached 140°, as measured by spectroscopic ellipsometry, reached 1.8 to 2.0 eV, thereby forming the lower layer of the light-shielding film. The sputtering process was carried out while the magnet's rotation speed increased from an initial 100 rpm at 11 rpm to a maximum of 155 rpm.

[0433] After forming the lower layer of the light-shielding film, a sputtering gas with a flow rate ratio of Ar:N2 = 57:43 was injected into the chamber. Then, while applying a sputtering power of 1.85 kW and rotating the magnet, sputtering was continued until the photon energy at the point where the phase difference between the P-wave and S-wave reached 140°, as measured by spectroscopic ellipsometry, reached 2.75 to 2.95 eV, thus forming the upper layer of the light-shielding film.

[0434] A total of 2 samples were prepared by applying the film forming conditions described above.

[0435] Example 2: The sputtering process was performed under the same conditions as in Example 1, wherein the magnetic force of the magnet was 45 mT. The process was performed until the photon energy at the point where the Del_1 value was 0 reached 1.89 eV.

[0436] Example 3: The sputtering process was carried out under the same conditions as in Example 1, wherein the composition of the sputtering gas was changed to a ratio of Ar:N2:He=8:58:34.

[0437] Example 4: A transparent quartz substrate measuring 6 inches in length, 6 inches in width, and 0.25 inches in thickness was placed in the chamber of a DC sputtering apparatus. A target composed of molybdenum and silicon at an atomic ratio of 1:9 was placed in the chamber, with a T / S distance of 255 mm and a 25-degree angle between the substrate and the target. A magnet with a magnetic field of 40 mT was placed behind the target.

[0438] A sputtering gas mixture of Ar, N₂, and He in a ratio of 9:52:39 was then introduced into the chamber. The sputtering power was adjusted to 2 kW, and the magnet was rotated at 150 rpm while the sputtering process was carried out. The thin film formation area was limited to a 132 mm long and 132 mm wide region on the surface of the transparent substrate. The sputtering process was continued until the photon energy reached 2.0 eV at the point where the Del_1 value reached zero.

[0439] After sputtering, the excimer UV light with a wavelength of 172nm was used at 7mW / cm 2 The phase shift film surface of the blank mask was exposed for 5 minutes at a power of .

[0440] The blank mask was then placed in a heat treatment chamber and annealed at 400°C for 30 minutes at 1 Pa, followed by natural cooling. After the natural cooling, O₂ was introduced into the heat treatment chamber at a rate of 1 SLM for 30 minutes. The O₂ supply temperature was approximately 300°C.

[0441] A light-shielding film sputtering process was performed on the surface of the formed phase-shift film. Specifically, the transparent substrate with the phase-shift film formed thereon and a chromium target were placed in a sputtering chamber. A sputtering gas flow ratio of Ar:N2:He:CO2 = 19:11:34:37 ​​was introduced into the chamber, and sputtering was performed at a sputtering voltage of 1.35 kW. Sputtering was continued until the photon energy reached 1.9 eV at the point where the phase difference between the P-wave and S-wave reached 140°, as measured by spectroscopic ellipsometry. This formed the lower layer of the light-shielding film.

[0442] Then, sputtering was carried out by introducing a sputtering gas flow rate ratio of Ar:N2 = 57:43 into the chamber and applying a sputtering voltage of 2.75 kW. Sputtering was continued until the photon energy reached 2.75 eV at the point where the phase difference between the P-wave and S-wave reached 140 degrees, as measured by spectroscopic ellipsometry. This formed the upper layer of the light-shielding film.

[0443] A total of 2 samples were prepared by applying the film forming conditions described above.

[0444] Example 5: The sputtering process is carried out under the same conditions as in Example 4, wherein the magnetic force is 45 mT and the process is carried out until the photon energy at the point where the Del_1 value is 0 reaches 1.89 eV.

[0445] Example 6: The sputtering process was carried out under the same conditions as in Example 4, wherein the composition of the sputtering gas was changed to a ratio of Ar:N2:He=8:58:34.

[0446] Comparative Example 1: A transparent quartz substrate measuring 6 inches in length, 6 inches in width, and 0.25 inches in thickness was placed in the chamber of a DC sputtering apparatus. A target composed of molybdenum and silicon at an atomic ratio of 1:9 was placed in the chamber, with a T / S distance of 255 mm and a 25-degree angle between the substrate and the target. A magnet with a magnetic field of 60 mT was placed behind the target.

[0447] Then, a sputtering gas mixture of Ar:N2:He = 9:52:39 was introduced into the chamber. The sputtering power was adjusted to 2 kW, and the magnet was rotated at 100 rpm while the sputtering process was carried out. The thin film formation area was limited to an area on the surface of the transparent substrate, with a length and width set to 132 mm. The sputtering process was continued until the photon energy reached 2.0 eV at the point where the Del_1 value was zero. No UV light treatment or annealing was applied after film formation.

[0448] A light-shielding film sputtering process was performed on the surface of the formed phase-shift film. Specifically, a chromium target and a transparent substrate with a phase-shift film formed thereon were placed in a sputtering chamber, with a T / S distance of 255 mm and a 25-degree angle between the substrate and the target. A magnet with a 60 mT magnetic field was placed behind the target.

[0449] A sputtering gas with a flow rate ratio of Ar:N2:He:CO2 = 19:11:34:37 ​​was injected into the chamber. Then, while applying a sputtering power of 1.35 kW and rotating the magnet at 100 rpm, sputtering was performed until the photon energy reached 1.8 to 2.0 eV at the point where the phase difference between the P-wave and S-wave reached 140°, as measured by spectroscopic ellipsometry. This formed the lower layer of the light-shielding film. This sputtering process was carried out.

[0450] After forming the lower layer of the light-shielding film, a sputtering gas with a flow rate ratio of Ar:N2 = 57:43 was injected into the chamber. Then, a sputtering power of 1.85 kW was applied while the magnet rotated, and sputtering was continued until the photon energy reached 2.75 to 2.95 eV at the point where the phase difference between the P-wave and S-wave reached 140°, as measured by spectroscopic ellipsometry. This formed the upper layer of the light-shielding film.

[0451] Comparative Example 2: The sputtering process was performed under the same conditions as Comparative Example 1, except that the magnetic force of the magnet was 20 mT. In addition, no additional heat treatment process was applied.

[0452] Comparative Example 3: A transparent quartz substrate measuring 6 inches in length, 6 inches in width, and 0.25 inches in thickness was placed in the chamber of a DC sputtering apparatus. A target composed of molybdenum and silicon at an atomic ratio of 1:9 was placed in the chamber, with a T / S distance of 255 mm and a 25-degree angle between the substrate and the target. A magnet with a magnetic field of 60 mT was placed behind the target.

[0453] Then, a sputtering gas mixture of Ar:N2:He = 9:52:39 was introduced into the chamber. The sputtering power was adjusted to 2 kW, and the magnet was rotated at 100 rpm while the sputtering process was carried out. The thin film formation area was limited to an area set to 132 mm in length and 132 mm in width on the surface of the transparent substrate. The sputtering process was continued until the photon energy reached 2.0 eV at the point where the Del_1 value was 0. No additional UV light treatment or heat treatment was applied.

[0454] A light-shielding film sputtering process was performed on the surface of the formed phase-shift film. Specifically, the transparent substrate with the phase-shift film formed thereon and a chromium target were placed in a sputtering chamber. A sputtering gas flow ratio of Ar:N2:He:CO2 = 19:11:34:37 ​​was introduced into the chamber, and sputtering was performed at a sputtering power of 1.35 kW. Sputtering was continued until the photon energy reached 1.9 eV at the point where the phase difference between the P-wave and S-wave reached 140°, as measured by spectroscopic ellipsometry. This formed the lower layer of the light-shielding film.

[0455] Then, sputtering was carried out by introducing a sputtering gas flow rate ratio of Ar:N2 = 57:43 into the chamber and applying a sputtering power of 2.75 kW. Sputtering was continued until the photon energy reached 2.75 eV at the point where the phase difference between the P-wave and S-wave reached 140°, as measured by spectroscopic ellipsometry. This formed the upper layer of the light-shielding film.

[0456] Comparative Example 4: The sputtering process was carried out under the same conditions as Comparative Example 3, wherein the magnetic force of the magnet was 20 mT and the composition of the sputtering gas was changed to Ar:N2:He=8:58:34.

[0457] Before forming the light-shielding films, the samples of Examples 1 to 3 and Comparative Examples 1 and 2 were measured for the distribution of Del_1 values ​​using a spectroscopic ellipsometer (MG-PRO, manufactured by NANO-VIEW) installed in the sputtering equipment. Specifically, the incident light angle was set to 64.5 degrees on the surface of the phase shift films formed in each Example and Comparative Example. The phase difference between the P-wave and S-wave, depending on the photon energy, was measured and converted into Del_1 values. The measurement results of parameters related to the Del_1 values ​​are shown in Table 2 below.

[0458] Evaluation example: XRD analysis

[0459] Normal mode XRD analysis and fixed mode XRD analysis were performed on the lower surface of the transparent substrate of the samples of Examples 1 to 3, Comparative Examples 1, and Comparative Examples 2, and on the upper surface of the light-shielding film of the samples. The light-shielding film included in the samples was then removed by etching and cleaning processes to expose the phase shift film.

[0460] Normal mode XRD analysis and fixed mode XRD analysis were performed on the exposed phase shift film.

[0461] The normal mode XRD analysis was carried out under the following conditions:

[0462] Equipment Name: Rigaku smartlab

[0463] X-ray source: copper target

[0464] X-ray information: wavelength 1.542nm, 45kV, 200mA

[0465] (θ-2θ) measurement range: 10~100°

[0466] Step: 0.05°

[0467] Speed: 5° / min

[0468] The XRD analysis of the fixed mode was carried out under the following conditions:

[0469] Equipment Name: Rigaku smartlab

[0470] X-ray source: copper target

[0471] X-ray information: wavelength 1.542nm, 45kV, 200mA

[0472] X-ray generator output angle: 1°

[0473] (θ-2θ) measurement range: 10~100°

[0474] Step: 0.05°

[0475] Speed: 5° / min

[0476] The measurement results of Examples and Comparative Examples are shown in Table 1 below.

[0477] Evaluation Example: Del_1 Value Measurement

[0478] The light shielding film was removed by etching in the samples of Examples 4 to 6 and Comparative Examples 3 and 4. Specifically, each sample was placed in a chamber, and an etching process was performed by supplying a chlorine-based gas as an etchant to remove the light shielding film.

[0479] The samples were then measured using a spectroscopic ellipsometer (MG-PRO, manufactured by NANO-VIEW) within the sputtering system to determine the distribution of Del_1 values ​​when PE1 was 1.5 eV and PE2 was 5.0 eV. Specifically, the incident light angle was set to 64.5 degrees on the surface of the phase shift films formed in each of the Examples and Comparative Examples. The phase difference between the P-wave and S-wave, depending on the photon energy, was measured and converted into a Del_1 value.

[0480] The parameters related to the distribution of the Del_1 value measured for each of the samples are described in Table 2 below. A graph showing the distribution of the DPS value and Del_1 value measured for each of the samples is described in Figures 12 to 21 .

[0481] Evaluation example: Phase difference and transmittance measurement

[0482] For the examples and samples described in the previous preparation examples, the light-shielding film was removed using the same etching method as described in the XRD analysis method. Retardation and transmittance were measured using a phase difference / transmittance meter (Lasertec MPM193). Specifically, an ArF light source (wavelength 193 nm) was used to illuminate the area of ​​each sample where the phase shift film was formed and the area where the phase shift film was not formed. The phase difference and transmittance difference between the light passing through the two areas were calculated and reported in Table 3 below.

[0483] Evaluation Example: Contrast and CD Value Measurement

[0484] After forming a photoresist film on the surface of the phase-shift film of each sample in the Examples and Comparative Examples, a dense quadrilateral pattern was exposed on the photoresist film using a Nuflare EBM 9000. The target CD value of the quadrilateral pattern was set to 400 nm (4X). After developing the pattern on the photoresist film of each sample, the light-shielding film and phase-shift film were etched according to the developed pattern using an Applied Materials Tetra X. The photoresist pattern was then removed.

[0485] For each sample including a phase shift film pattern in the Examples and Comparative Examples, the contrast and normalized CD values ​​of the pattern developed by the wafer exposure process were measured and calculated using a Carl Zeiss AIMS 32, based on the Del_1 value of the phase shift film. The numerical aperture (NA) used for the measurements and calculations was 1.35, and the illuminometer settings were set to a crosspole of 30X, an outer sigma of 0.8, and an input / output sigma ratio of 85%. The measured data are reported in Table 3 below.

[0486] Evaluation Example: Measurement and Evaluation of the Content of Each Element in the Thickness Direction of the Protective Layer

[0487] The content of each element along the thickness of the protective layer was measured for the samples in Examples 4 to 6 and Comparative Examples 3 and 4. Specifically, a Thermo Scientific K-alpha analyzer was used, using a 180° dual-focusing hemispherical analyzer with 120 channels, an Al Ka ​​micro-focused X-ray source with an energy of 1 keV, an operating pressure of 1E-7 mbar, and Ar gas.

[0488] The measurement results showed that the protective layer included a region having a nitrogen content to oxygen content ratio of 0.4 to 2 in the thickness direction. When the region had a thickness of 30 to 80% of the overall thickness of the protective layer, the evaluation was 0, and when the region had a thickness of less than 30% or greater than 80% of the overall thickness of the protective layer, the evaluation was X. The measurement results are recorded in Table 3 below.

[0489] [Table 1]

[0490] AI1 AI2 AI3 AI4 AI5 AI6 Example 1 1.00 1.02 1.01 0.99 0.96 1.0938 Example 2 1.01 1.02 1.02 0.99 0.95 1.10 Example 3 1.00 1.03 1.02 1.00 0.93 1.11 Example 4 - - - - - - Example 5 - - - - - - Example 6 - - - - - - Comparative Example 1 0.97 0.96 0.94 1.05 0.99 1.05 Comparative Example 2 0.94 0.95 0.93 1.02 0.98 1.05 Comparative Example 3 - - - - - - Comparative Example 4 - - - - - -

[0491] [Table 2]

[0492]

[0493] [Table 3]

[0494]

[0495]

[0496] In Table 1, the AI1, AI2, AI3, and AI4 values ​​of Examples 1 to 3 are closer to 1 than those of Comparative Examples 1 and 2.

[0497] In Table 3, the transmittance of Examples 1 to 6 is in the range of 5.4 to 6.9%, and the phase difference is in the range of 170 to 190°. However, the transmittance of Comparative Examples 1 and 3 is less than 4%, and the phase difference is greater than 200°. The transmittance of Comparative Examples 2 and 4 is greater than 7.4%, and the phase difference is less than 170°.

[0498] In the evaluation of each element composition in the thickness direction of the protective layer, Examples 4 to 6 were evaluated as O, whereas Comparative Examples 3 and 4 were evaluated as X.

[0499] Examples 1 to 6 exhibited normalized contrast ratios of 0.95 or greater and normalized CD values ​​of 1.03 or less, whereas Comparative Examples 1 to 4 exhibited normalized contrast ratios of less than 0.93 and normalized CD values ​​of 1.06 or greater.

[0500] 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 also fall within the scope of the claims of the present invention.

Claims

1. A blank mask, wherein: include: Transparent substrate; a phase shift film, disposed on the transparent substrate; as well as a light-shielding film, disposed on the phase shift film, 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_1 is 0 expressed by the following equation 7 is 3.8 eV to 4.64 eV; [Formula 7] In Formula 7, when the light-shielding film is removed from the blank mask and the surface of the phase shift film is measured using an ellipsometer at an incident angle of 64.5°, if the phase difference between the P wave and the S wave of the reflected light is 180° or less, the DPS value is the phase difference between the P wave and the S wave. If the phase difference between the P wave and the S wave of the reflected light is greater than 180°, the DPS value is the value 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 from PE1 to PE2.

2. The blank mask according to claim 1, wherein 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_1 value is 0 is 1.8 eV to 2.14 eV.

3. The blank mask according to claim 1, wherein When the PE1 value is 1.5 eV and the PE2 value is the minimum value of the photon energy of the incident light at the point where the Del_1 value is 0, the average value of the Del_1 value is 78° / eV to 98° / eV.

4. The blank mask according to claim 1, wherein When the PE1 value is the minimum value of the photon energy of the incident light at the point where the Del_1 value is 0, and the PE2 value is the maximum value of the photon energy of the incident light at the point where the Del_1 value is 0, the average value of the Del_1 value is -65° / eV to -55° / eV.

5. The blank mask according to claim 1, wherein When the PE1 value is the maximum value among the photon energies of the incident light at the point where the Del_1 value is 0 and the PE2 value is 5.0 eV, the average value of the Del_1 value is 60° / eV to 120° / eV. The blank mask according to claim 1 , wherein: When the PE1 value is 1.5 eV and the PE2 value is 5.0 eV, the maximum value of the Del_1 value is 105° / eV to 300° / eV.

7. The blank mask according to claim 6, wherein: The photon energy at the point where the Del_1 value reaches the maximum value is 4.5 eV or more.

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