Phase shift mask for EUV lithography and method of manufacturing the same

Abstract

The present disclosure relates to a phase shift mask for EUV lithography and a manufacturing method of the phase shift mask. A phase shift mask for extreme ultraviolet lithography and a method of manufacturing the phase shift mask are provided. The phase shift mask includes a substrate, a reflective layer, a device pattern, a frame pattern, or a phase shift pattern. The frame pattern is a pattern including an alignment hole exposing a portion of the reflective layer. The phase shift pattern overlaps the device pattern.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a lithography technique, and more particularly, to a phase shift mask for extreme ultraviolet (EUV) lithography and a manufacturing method thereof. BACKGROUND

[0002] As semiconductor integrated circuits are integrated with finer size patterns, a lithography process requires an exposure light source of a shorter wavelength band. To achieve a fine circuit line width, a technique of using extreme ultraviolet (EUV) in a wavelength band of about 13.5 nanometers (nm) as an exposure light is being recognized. In the extreme ultraviolet lithography technique, a reflective mask structure is applied. To improve the resolution of the extreme ultraviolet, a phase shift mask structure in which a phase shift structure is applied to the reflective mask structure has been attempted. SUMMARY

[0003] An embodiment of the present disclosure can provide a phase shift mask including a reflective layer formed on a substrate, a device pattern formed on the reflective layer, a frame pattern formed on the reflective layer, the frame pattern including an alignment hole exposing a portion of the reflective layer, and a phase shift pattern overlapping the device pattern.

[0004] Another embodiment of the present disclosure can provide a method of manufacturing a phase shift mask, the method including forming a reflective layer on a substrate, forming an underlayer on the reflective layer, forming a phase shift upper layer on the underlayer, patterning a first phase shift pattern from the phase shift upper layer by sequentially etching the phase shift upper layer and the underlayer and patterning a device pattern overlapping the first phase shift pattern and a frame pattern overlapping a second phase shift pattern providing an alignment hole from the underlayer, and selectively removing the second phase shift pattern. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figure 1 And Figure 2 is a schematic view illustrating a phase shift mask for extreme ultraviolet lithography according to an embodiment of the present disclosure.

[0006] Figure 3 is a schematic view illustrating an extreme ultraviolet lithography system according to an embodiment of the present disclosure.

[0007] Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 and Figure 10 is a schematic view illustrating a manufacturing method of a phase shift mask for extreme ultraviolet lithography according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0008] The terms used in the description of the embodiments of the present disclosure are terms selected on the basis of functions in the proposed embodiments, and meanings of the terms can vary according to intentions of a user or an operator, or customs in the art. When specifically defined in the present disclosure, the meanings of the terms used are those defined in the present disclosure, and if not specifically defined, can be interpreted as meanings generally accepted by those skilled in the art.

[0009] In the description of the embodiments of the present disclosure, descriptions such as "first", "second", "side", "top", and "bottom or lower" are used to distinguish auxiliary materials, not to limit the auxiliary materials themselves or to imply any particular order, which means a relative positional relationship, but not to limit a particular case in which the auxiliary materials are directly contacted or further introduced into an interface with another auxiliary material. The same explanation can be applied to other expressions describing the relationship between components.

[0010] Embodiments of the present disclosure can be applied to the technical field of implementing integrated circuits such as DRAM, PcRAM, or ReRAM devices. In addition, embodiments of the present disclosure can be applied to the technical field of implementing memory devices such as SRAM, FLASH, MRAM, or FeRAM, or logic devices integrated with logic integrated circuits. Embodiments of the present disclosure can be applied to the technical field of implementing various products requiring a fine pattern.

[0011] Throughout the present disclosure, the same reference numbers can refer to the same elements. The same reference numbers or similar reference numbers can be described with reference to other drawings even if not mentioned or described in the corresponding drawing. In addition, even if the reference numbers are not indicated, they can be described with reference to other drawings.

[0012] Figure 1 is a schematic cross-sectional view showing a cross-sectional shape of a phase shift mask 10 for extreme ultraviolet lithography according to an embodiment of the present disclosure. Figure 2 is a schematic plan view showing a planar shape of a phase shift mask 10 for extreme ultraviolet lithography according to an embodiment of the present disclosure. Figure 1 shows a cross-sectional shape along a line X1-X2 of Figure 2 .

[0013] Referring to Figure 1 , a phase shift mask 10 for extreme ultraviolet lithography can include a substrate 100, a reflective layer 300, a lower layer 400, and a phase shift upper layer 500. The lower layer 400 can be formed on the reflective layer 300. The lower layer 400 can include a device pattern 401 and a frame pattern 402 formed on the reflective layer 300. The phase shift upper layer 500 can include a phase shift pattern 501 and an edge ring pattern 502. The phase shift mask 10 having the above-described configuration can be used as a photomask in a lithography process using extreme ultraviolet light as a light source.

[0014] The phase shift mask 10 can include a reflective photomask structure that reflects incident extreme ultraviolet rays. The reflective layer 300 of the phase shift mask 10 can be formed on the substrate 100. The reflective layer 300 can be formed to cover the upper surface 100S of the substrate 100. The substrate 100 can be a basis on which the reflective layer 300 is formed. The substrate 100 can include a material having a low thermal expansion material (LTEM). The substrate 100 can include quartz, aluminosilicate glass, or a silicon oxide-titanium oxide (SiO2-TiO2)-based glass.

[0015] The reflective layer 300 of the phase shift mask 10 can be a layer having a structure that reflects extreme ultraviolet rays within a wavelength band of, for example, 13.5 nm. The reflective layer 300 can have a layer structure that achieves a reflectance of about 58% to 60% with respect to incident extreme ultraviolet rays. The reflective layer 300 can include a multilayer 200 in which a first reflective layer 210 and a second reflective layer 220 are alternately stacked multiple times. The first reflective layer 210 and the second reflective layer 220 can be material layers having different refractive indices n with respect to extreme ultraviolet rays. The multilayer 200 in which the first reflective layer 210 and the second reflective layer 220 are alternately and repeatedly stacked can constitute a mirror structure that reflects incident extreme ultraviolet rays. The first reflective layer 210 can include a silicon (Si) layer, and the second reflective layer 220 can include a molybdenum (Mo) layer.

[0016] The reflective layer 300 can further include a capping layer 310 that covers the multilayer 200. The capping layer 310 can protect the multilayer 200 from external environments by covering the upper surface of the multilayer 200 to prevent or mitigate defects from occurring in the multilayer 200. The capping layer 310 can be formed of a material having a low extinction coefficient k with respect to extreme ultraviolet rays (e.g., a material having an extinction coefficient of 0.005 to 0.04). The capping layer 310 can include a ruthenium (Ru) layer.

[0017] The device pattern 401 and the frame pattern 402 can be formed on the reflective layer 300 to be spaced apart from each other. The device pattern 401 and the frame pattern 402 can be positioned at the same height. The device pattern 401 and the frame pattern 402 can be patterned from the underlayer 400 to be separated from each other. The device pattern 401 can be positioned to overlap the first region 101 of the substrate 100. The frame pattern 402 can be positioned to overlap the second region 102 of the substrate 100. The first region 101 of the substrate 100 can be a central portion of the substrate 100, and the second region 102 of the substrate 100 can be an edge region surrounding the first region 101.

[0018] Reference will now be made to Figure 1 and Figure 2The device pattern 401 can be an image transfer pattern having an image to be transferred to a wafer by an extreme ultraviolet lithography process. The first region 101 of the substrate 100 can be a region where a pattern to be transferred to a wafer by an extreme ultraviolet lithography process is disposed. The second region 102 of the substrate 100 can be a region where an image is prohibited from being transferred to a wafer by an extreme ultraviolet lithography process. The frame pattern 402 can be a pattern having an image prohibited from being transferred to a wafer by an extreme ultraviolet lithography process.

[0019] The device pattern 401 can be a pattern having a relatively small line width compared to the frame pattern 402. The frame pattern 402 can have a ring shape or a ring shape surrounding the device pattern 401. In an embodiment, the frame pattern 402 can be formed to surround a periphery of a group of device patterns 401 or all of the device patterns 401, as shown in Figure 1 and Figure 2 The frame pattern 402 can be a ring pattern surrounding the first region 101 of the substrate 100. The frame pattern 402 can block a portion of the reflective layer 300 overlapping the second region 102 to substantially block reflection of extreme ultraviolet in the portion of the reflective layer 300 overlapping the second region 102. Accordingly, the frame pattern 402 can be used to block transfer of an image from the second region 102 of the substrate 100 to a wafer.

[0020] The frame pattern 402 can be a pattern providing an alignment hole 420. The alignment hole 420 can be a reference mark or an alignment mark used to check a position of the phase shift mask 10 when performing an extreme ultraviolet lithography process. The alignment hole 420 can be in the form of a through hole penetrating the frame pattern 402 substantially perpendicularly. The alignment hole 420 can be a through hole exposing a portion of an area of a bottom of the reflective layer 300.

[0021] Figure 3 is a schematic view illustrating an extreme ultraviolet lithography system 90 according to an embodiment of the disclosure.

[0022] Referring to Figure 2 and Figure 3 together, a system 90 performing an EUV lithography process can include a controller 91, an EUV light source unit 96, a position checker 98, and a mask loader 95. The phase shift mask 10 can be loaded on the mask loader 95, and extreme ultraviolet rays 97A generated from the EUV light source unit 96 can be incident on the phase shift mask 10. The extreme ultraviolet rays 97B can be reflected from the phase shift mask 10, and the reflected extreme ultraviolet rays 97B can be incident on the resist layer 21 formed on the wafer 20. Accordingly, a pattern image can be transferred from the phase shift mask 10 to the resist layer 21.

[0023] After the phase shift mask 10 is loaded on the mask loader 95, a process of checking a position where the phase shift mask 10 is loaded can be performed. The inspection light 94A can be irradiated to the phase shift mask 10 from the inspection light source unit 92 of the position checker 98, and the inspection light 94B reflected from the phase shift mask 10 can be received by the inspection light receiver 93. The inspection light 94A can scan the frame pattern 402 and the alignment hole 420 of the phase shift mask 10, and the inspection light receiver 93 can receive the inspection light 94B reflected from the frame pattern 402 and the alignment hole 420.

[0024] The frame pattern 402 is formed of a material having a reflectivity lower than that of the reflective layer 300 with respect to the incident inspection light 94A. Accordingly, the intensity of the inspection light 94B reflected from the portion 302 of the reflective layer 300 exposed at the bottom of the alignment hole 420 can be relatively greater than that of the inspection light reflected from the surface of the frame pattern 402. The position of the alignment hole 420 can be checked from the intensity distribution of the reflected inspection light 94B according to the scanning direction of the incident inspection light 94A. Since the position of the alignment hole 420 indicates the position of the phase shift mask 10, the position of the phase shift mask 10 can be detected by checking the position of the alignment hole 420.

[0025] In order to distinguish the signal or intensity of the inspection light 94B reflected from the alignment hole 420 or the bottom of the alignment hole 420 from that of the inspection light 94B reflected from the surface of the frame pattern 402, the frame pattern 402 can have a relatively lower reflectivity with respect to the incident inspection light 94A than the reflective layer 300. As the inspection light 94A used in the process of checking the loaded position of the phase shift mask 10, a light source in a wavelength range of about 248 nm to about 900 nm can be used. As the inspection light 94A, a light source in a wavelength band of about 405 nm or a light source in a wavelength band of about 880 nm can be used.

[0026] The reflectivity of the frame pattern 402 or the underlayer 400 with respect to a light source in a wavelength range of about 248 nm to about 900 nm can be relatively lower than that of the reflective layer 300 with respect to a light source in a wavelength range of about 248 nm to about 900 nm. The reflectivity of the frame pattern 402 or the underlayer 400 with respect to a light source in a wavelength range of about 405 nm and about 880 nm can be relatively lower than that of the reflective layer 300 with respect to a light source in a wavelength range of about 405 nm and about 880 nm.

[0027] The reflectivity of the frame pattern 402 or the underlayer 400 relative to light sources within a wavelength band of about 248 nm to about 900 nm can be about 50% or less of the reflectivity of the reflective layer 300 relative to light sources within a wavelength band of about 248 nm to about 900 nm. The reflectivity of the frame pattern 402 or the underlayer 400 relative to light sources within a wavelength range of about 405 nm and about 880 nm can be about 50% or less of the reflectivity of the reflective layer 300 relative to light sources within a wavelength range of about 405 nm and about 880 nm.

[0028] The reflectivity of the frame pattern 402 or the underlayer 400 relative to light sources within a wavelength range of about 248 nm to about 900 nm can be about 2% to 30%. The reflectivity of the frame pattern 402 or the underlayer 400 relative to light sources within a wavelength band of about 405 nm and light sources within a wavelength band of about 880 nm can be about 2% to 30%.

[0029] The reflectivity of the reflective layer 300 relative to light sources within a wavelength range of about 248 nm to about 900 nm can be about 58% to 60%.

[0030] Accordingly, the reflectivity of the frame pattern 402 relative to the inspection light 94A is relatively significantly lower than the reflective layer 300, such that detection and inspection for the alignment hole 420 can be effectively performed.

[0031] Referring again to FIG. 4, Figure 1 The frame pattern 402 or the underlayer 400 can include a low-reflective material layer having a relatively low reflectivity relative to light sources within a wavelength range of about 248 nm to about 900 nm. The low-reflective material layer or the frame pattern 402 or the underlayer 400 can be formed to include a material layer of ruthenium (Ru), silicon (Si), molybdenum (Mo), tantalum (Ta), titanium (Ti), or zirconium (Zr). The frame pattern 402 or the underlayer 400 can be formed to include a material layer of at least one of ruthenium (Ru), silicon (Si), molybdenum (Mo), tantalum (Ta), titanium (Ti), and zirconium (Zr). The frame pattern 402 or the underlayer 400 can be formed to include a material layer of oxides or nitrides of ruthenium (Ru), silicon (Si), molybdenum (Mo), tantalum (Ta), titanium (Ti), and zirconium (Zr). The frame pattern 402 or the underlayer 400 can be formed to include a material layer of silicon nitride (Si3N4), silicon oxide (SiO2), silicon oxynitride (SiON), tantalum oxide (Ta2O5), titanium oxide (TiO2), hafnium oxide (HfO2), or zirconium oxide (ZrO2). The frame pattern 402 or the underlayer 400 can be formed to include a material layer of at least one of silicon nitride (Si3N4), silicon oxide (SiO2), silicon oxynitride (SiON), tantalum oxide (Ta2O5), titanium oxide (TiO2), hafnium oxide (HfO2), and zirconium oxide (ZrO2).

[0032] Titanium oxide has been found to have a reflectivity of about 3% with respect to inspection light in the 405 nm wavelength band and about 24% with respect to inspection light in the 880 nm wavelength band. Thus, it can be effective for the frame pattern 402 or the underlying layer 400 to be formed as a titanium oxide layer.

[0033] Silicon oxide has been found to have a reflectivity of about 22% with respect to inspection light in the 405 nm wavelength band and about 30% with respect to inspection light in the 880 nm wavelength band. Silicon nitride has been found to have a reflectivity of about 12% with respect to inspection light in the 405 nm wavelength band and about 28% with respect to inspection light in the 880 nm wavelength band. Tantalum oxide has been found to have a reflectivity of about 9% with respect to inspection light in the 405 nm wavelength band and about 28% with respect to inspection light in the 880 nm wavelength band. Hafnium oxide has been found to have a reflectivity of about 15% with respect to inspection light in the 405 nm wavelength band and about 30% with respect to inspection light in the 880 nm wavelength band. Zirconium oxide has been found to have a reflectivity of about 10% with respect to inspection light in the 405 nm wavelength band and about 27% with respect to inspection light in the 880 nm wavelength band.

[0034] Since the frame pattern 402 or the underlying layer 400 includes silicon nitride (Si3N4), silicon oxide (SiO2), silicon oxynitride (SiON), tantalum oxide (Ta2O5), titanium oxide (TiO2), hafnium oxide (HfO2), and zirconium oxide (ZrO2), the alignment hole 420 can be more effectively detected by scanning inspection light (94A) in the 405 nm wavelength band. Figure 3

[0035] The device pattern 401 can be formed to include substantially the same material as the frame pattern 402. The device pattern 401 can include silicon nitride (Si3N4), silicon oxide (SiO2), silicon oxynitride (SiON), tantalum oxide (Ta2O5), titanium oxide (TiO2), hafnium oxide (HfO2), or zirconium oxide (ZrO2).

[0036] Referring to Figure 1 The phase shift pattern 501 of the upper layer 500 for phase shifting can be formed to overlap the device pattern 401. The phase shift pattern 501 can be patterned to have substantially the same planar shape or pattern shape as the device pattern 401. The phase shift pattern 501 can be aligned with the device pattern 401 and patterned to substantially completely overlap the device pattern 401.

[0037] ​The edge ring pattern 502 can be formed to be spaced apart from the phase shift pattern 501. The edge ring pattern 502 can be positioned at the same height as the phase shift pattern 501. The edge ring pattern 502 and the phase shift pattern 501 can be patterned to be separated from the phase shift upper layer 500. The phase shift pattern 501 can be positioned to overlap the first area 101 of the substrate 100 in the same manner as the device pattern 401. The edge ring pattern 502 can overlap a portion of the frame pattern 402. The edge ring pattern 502 can be positioned to overlap a portion of the second area 102 of the substrate 100.

[0038] The phase shift pattern 501 can be used to improve resolution of an image transferred by the phase shift mask 10. The phase shift upper layer 500 or the phase shift pattern 501 can be formed as a layer that reflects extreme ultraviolet (EUV) rays. The phase shift upper layer 500 or the phase shift pattern 501 can be formed as a phase shift layer that reflects EUV rays at a phase difference of 180 degrees (°) to 300 degrees (°) from EUV rays reflected by the reflective layer 300. The phase shift pattern 501 or the phase shift upper layer 500 can be formed as a phase shift layer having a reflectivity of 5% to 60% with respect to EUV. The phase shift pattern 501 or the phase shift upper layer 500 can be formed as a phase shift layer of a material having a refractive index of 0.87 to 0.96 and an extinction coefficient of 0.005 to 0.04 with respect to EUV.

[0039] The phase shift pattern 501 or the phase shift upper layer 500 can include a phase shift layer including at least one of ruthenium (Ru), molybdenum (Mo), niobium (Nb), tantalum (Ta), titanium (Ti), and zirconium (Zr). The phase shift pattern 501 or the phase shift upper layer 500 can include a phase shift layer including ruthenium (Ru), molybdenum (Mo), niobium (Nb), tantalum (Ta), titanium (Ti), or zirconium (Zr). The phase shift layer can include a combination of at least two or more materials of ruthenium (Ru), molybdenum (Mo), niobium (Nb), tantalum (Ta), titanium (Ti), and zirconium (Zr). The phase shift layer can further include at least one of carbon (C), oxygen (O), and nitrogen (N) as an additive.

[0040] The phase shift pattern 501 or the phase shift upper layer 500 can include a molybdenum (Mo) layer having a thickness of about 60 nm. It is confirmed that EUV rays reflected from the phase shift pattern 501 of the molybdenum (Mo) layer have a phase difference of about 250 degrees (°) from EUV rays reflected from the reflective layer 300. It is confirmed that the phase shift pattern 501 of the molybdenum (Mo) layer has a reflectivity of about 40% with respect to EUV rays.

[0041] The phase shift pattern 501 or the phase shift upper layer 500 can include a ruthenium (Ru) layer having a thickness of about 40 nm. It is confirmed that extreme ultraviolet light reflected from the phase shift pattern 501 of the ruthenium (Ru) layer has a phase difference of about 250 degrees (°) from extreme ultraviolet light reflected from the reflective layer 300. It is confirmed that the phase shift pattern 501 of the ruthenium (Ru) layer has a reflectivity of about 20% with respect to extreme ultraviolet light.

[0042] The edge ring pattern 502 can include a phase shift layer substantially the same as the phase shift pattern 501. Extreme ultraviolet light reflected from the edge ring pattern 502 can have a phase difference from extreme ultraviolet light partially reflected from the adjacent reflective layer 300. Accordingly, the edge ring pattern 502 can improve resolution of an image of a pattern positioned at or near a boundary between the first region 101 and the second region 102 of the substrate 100. The edge ring pattern 502 can be formed in a ring shape or a pattern in a ring shape surrounding the phase shift pattern 501, as shown. Figure 2

[0043] Referring again to Figure 1 , the phase shift upper layer 500 including the phase shift pattern 501 or the edge ring pattern 502 is spaced apart from the alignment hole 420, and a majority of an area of the frame pattern 402 adjacent to the alignment hole 420 is exposed without being covered by the phase shift upper layer 500. Accordingly, even though the phase shift pattern 501 or the phase shift upper layer 500 has a relatively high reflectivity with respect to inspection light (94A) in the inspection light (94A), an effect of an inspection result of the phase shift upper layer 500 can be substantially excluded when the alignment hole 420 is scanned with the inspection light (94A) and a position of the alignment hole 420 is inspected. Figure 3

[0044] Figures 4 to 10 is a schematic cross-sectional view illustrating a manufacturing method of a phase shift mask for extreme ultraviolet lithography according to an embodiment of the disclosure.

[0045] Referring to Figure 4 , the reflective layer 300 can be formed on the substrate 100. The substrate 100 can include a first region 101 and a second region 102. The first region 101 of the substrate 100 can be a central portion of the substrate 100, and the second region 102 of the substrate 100 can be an edge region surrounding the first region 101. The substrate 100 can be a basis on which the reflective layer 300 is formed. The substrate 100 can include a low thermal expansion material (LTEM). The substrate 100 can include quartz, aluminosilicate glass, or a silicon oxide-titanium oxide (SiO2-TiO2)-based glass.

[0046] ​​The reflective layer 300 can be formed as a layer having a structure that reflects extreme ultraviolet rays (e.g., a wavelength band of 13.5 nm). The reflective layer 300 can have a layer structure that achieves a reflectance of about 58% to 60% with respect to incident extreme ultraviolet rays. The reflective layer 300 can include a multilayer 200 in which a first reflective layer 210 and a second reflective layer 220 are alternately stacked multiple times. The first reflective layer 210 and the second reflective layer 220 can be material layers having different refractive indices (n) with respect to extreme ultraviolet rays. The multilayer 200 in which the first reflective layer 210 and the second reflective layer 220 are alternately stacked can be formed as a mirror structure that reflects incident extreme ultraviolet rays. The first reflective layer 210 can include a silicon (Si) layer, and the second reflective layer 220 can include a molybdenum (Mo) layer.

[0047] The reflective layer 300 can further include a cover layer 310 that covers the multilayer 200. The cover layer 310 can cover an upper surface of the multilayer 200 to protect the multilayer 200 from an external environment. The cover layer 310 can be made of a material having a low extinction coefficient (k) with respect to extreme ultraviolet rays (e.g., a material having an extinction coefficient of 0.005 to 0.04). The cover layer 310 can include a ruthenium (Ru) layer.

[0048] A lower layer 400 can be formed on the reflective layer 300. The lower layer 400 can include a low reflective material layer having a relatively low reflectance with respect to light sources in a wavelength range of about 248 nm to about 900 nm. The reflectance of the lower layer 400 with respect to light sources in a wavelength range of about 248 nm to about 900 nm can be relatively lower than the reflectance of the reflective layer 300 with respect to light sources in a wavelength range of about 248 nm to about 900 nm. The reflectance of the lower layer 400 with respect to light sources in a wavelength range of about 405 nm and light sources in a wavelength range of about 880 nm can be relatively lower than the reflectance of the reflective layer 300 with respect to light sources in a wavelength range of about 405 nm and light sources in a wavelength range of about 880 nm.

[0049] The reflectance of the lower layer 400 with respect to light sources in a wavelength range of about 248 nm to about 900 nm can be about 50% or less lower than the reflectance of the reflective layer 300 with respect to light sources in a wavelength range of about 248 nm to about 900 nm. The reflectance of the lower layer 400 with respect to light sources in a wavelength range of about 405 nm and light sources in a wavelength range of about 880 nm can be about 50% or less lower than the reflectance of the reflective layer 300 with respect to light sources in a wavelength range of about 405 nm and light sources in a wavelength range of about 880 nm.

[0050] The reflectance of the lower layer 400 with respect to light sources in a wavelength range of about 248 nm to about 900 nm can be about 2% to 30%. The reflectance of the lower layer 400 with respect to light sources in a wavelength range of about 405 nm and light sources in a wavelength range of about 880 nm can be about 2% to 30%.

[0051] The lower layer 400 can include a material layer including silicon nitride (Si3N4), silicon oxide (SiO2), silicon oxynitride (SiON), tantalum oxide (Ta2O5), titanium oxide (TiO2), hafnium oxide (HfO2), or zirconium oxide (ZrO2).

[0052] The upper phase shift layer 500 can be formed on the lower layer 400. The upper phase shift layer 500 can include a layer that reflects incident extreme ultraviolet rays. The upper phase shift layer 500 can be formed as a phase shift layer having a phase difference of 180 degrees (°) to 300 degrees (°) between the extreme ultraviolet rays reflected by the upper phase shift layer 500 and the extreme ultraviolet rays reflected by the reflection layer 300. The upper phase shift layer 500 can be formed as a phase shift layer having a reflectance of 5% to 60% with respect to the extreme ultraviolet rays. The upper phase shift layer 500 can be formed as a phase shift layer including a material having a refractive index of 0.87 to 0.96 and an extinction coefficient of 0.005 to 0.04 with respect to the extreme ultraviolet rays.

[0053] The upper phase shift layer 500 can include a molybdenum (Mo) layer having a thickness of about 60 nm. The upper phase shift layer 500 can include a ruthenium (Ru) layer having a thickness of about 40 nm.

[0054] The hard mask layer 600 can be formed on the upper phase shift layer 500. The hard mask layer 600 can be used as a hard mask in a process of selectively etching the upper phase shift layer 500 and the lower layer 400. The hard mask layer 600 can be omitted according to a subsequent selective etching process. The hard mask layer 600 can include a chromium (Cr) layer or a chromium nitride (CrN) layer. It is verified that the chromium (Cr) layer has a reflectance of about 44% with respect to a light source having a wavelength of about 365 nm, a reflectance of about 42% with respect to a light source having a wavelength of about 405 nm, and a reflectance of about 43% with respect to a light source having a wavelength of about 880 nm.

[0055] Accordingly, the chromium (Cr) layer has a relatively high reflectance with respect to a wavelength band that can be used as an inspection light (94A in FIG. 10) and thus can be used as the hard mask layer 600, but can be excluded from the structure of the phase shift mask (10 in FIG. 10). As shown in FIG. 10, when the phase shift mask 10 is loaded onto the mask loader 95 and the position of the phase shift mask 10 is inspected, the inspection light reflected from the chromium (Cr) hard mask layer 600 can prevent the position of the alignment hole 420 from being inspected. Accordingly, the hard mask layer 600 can be removed through a separate removal process after a process of selectively etching the upper phase shift layer 500 and the lower layer 400. Figure 3 Figure 1 Figure 3

[0056] Referring to FIG. 11, the hard mask layer 600 can be omitted from the structure of the phase shift mask 10. As shown in FIG. 11, when the phase shift mask 10 is loaded onto the mask loader 95 and the position of the phase shift mask 10 is inspected, the inspection light reflected from the hard mask layer 600 can prevent the position of the alignment hole 420 from being inspected. Accordingly, the hard mask layer 600 can be omitted from the structure of the phase shift mask 10. Figure 5 ​​​A photoresist pattern 700 can be formed on the hard mask layer 600. The photoresist pattern 700 can be formed by forming a photoresist layer on the hard mask layer 600, performing an e-beam writing process on the photoresist layer, and developing the photoresist layer. The photoresist pattern 700 can be formed as an etch mask for selectively etching the hard mask layer 600, the phase shift upper layer 500, and the lower layer 400.

[0057] The photoresist pattern 700 can include a first photoresist pattern 701 and a second photoresist pattern 703, which are spaced apart from each other with respect to the respective regions 101 and 102 of the substrate 100. The first photoresist pattern 701 can be positioned to overlap the first region 101 of the substrate 100, and the second photoresist pattern 703 can be positioned to overlap the second region 102 of the substrate 100. The first photoresist pattern 701 can have a shape to be image-transferred onto a wafer by an extreme ultraviolet lithography process. The second photoresist pattern 703 can be formed as a pattern having an opening 720 having a shape for forming an alignment hole (420 in FIG. 4). Figure 1

[0058] Referring to Figure 6 A selective etching process using the photoresist pattern 700 as an etch mask can be performed. Using the photoresist pattern 700 as an etch mask, some portions of the phase shift upper layer 500 and some portions of the lower layer 400 can be sequentially etched and removed.

[0059] The first hard mask pattern 601 and the second hard mask pattern 603 can be formed by selectively etching away some portions of the hard mask layer 600 using the photoresist pattern 700 as an etch mask. The first hard mask pattern 601 can overlap the first photoresist pattern 701 and can be formed to have a shape conforming to a shape of the first photoresist pattern 701. The second hard mask pattern 603 can overlap the second photoresist pattern 703 and can be formed to have a shape conforming to a shape of the second photoresist pattern 703. The first hard mask pattern 601 and the second hard mask pattern 603 can function as a part of the etch mask of the photoresist pattern 700.

[0060] ​The etching process of removing some portions of the phase shift upper layer 500 and some portions of the lower layer 400 can continue in sequence using the photoresist pattern 700 and the first hard mask pattern 601 and the second hard mask pattern 603 as etching masks. Thus, the first phase shift pattern 501 and the second phase shift pattern 503 can be patterned from the phase shift upper layer 500. The first phase shift pattern 501 can overlap the first hard mask pattern 601 or the first photoresist pattern 701, and can be patterned to have a shape conforming to the shape of the first photoresist pattern 701. The second phase shift pattern 503 can overlap the second hard mask pattern 603 or the second photoresist pattern 703, and can be patterned to have a shape conforming to the shape of the second photoresist pattern 703. The second hard mask pattern 603 can be patterned in a pattern providing the alignment hole 420 or portions of the alignment hole 420 formed along the shape of the opening 720.

[0061] The device pattern 401 and the frame pattern 402 can be patterned from the lower layer 400. The device pattern 401 can overlap the first phase shift pattern 501, the first hard mask pattern 601, or the first photoresist pattern 701, and can be patterned to have a shape conforming to the shape of the first photoresist pattern 701. The frame pattern 402 can overlap the second phase shift pattern 503, the second hard mask pattern 603, or the second photoresist pattern 703, and can be patterned to have a shape conforming to the shape of the second photoresist pattern 703. The frame pattern 402 can be patterned in a pattern providing the alignment hole 420 or portions of the alignment hole 420 formed along the shape of the opening 720.

[0062] Referring to Figure 7 The photoresist pattern (700 in Figure 6 ) used as an etching mask can be selectively removed.

[0063] Referring to Figure 8 The hard mask pattern (601 and 603 in Figure 6 ) used as a portion of an etching mask can be selectively removed.

[0064] Referring to Figure 9 A shielding pattern 800 exposing a portion 504 of the second phase shift pattern 503 or each second phase shift pattern can be formed. The shielding pattern 800 can cover or protect the first phase shift pattern 501. The shielding pattern 800 can cover or protect the portion 301 of the reflective layer 300 between the first phase shift pattern 501. The shielding pattern 800 can cover or protect the portion 302 of the reflective layer 300 between the first phase shift pattern 501 and the second phase shift pattern 503. The shielding pattern 800 can cover or protect the local area 502 of the second phase shift pattern 503 facing the first phase shift pattern 501 while being adjacent to the first phase shift pattern 501.

[0065] The shielding pattern 800 may cover portions 301 and 302 of the reflective layer 300 that overlap with the first region 101 of the substrate 100 and the first phase-shifting pattern 501, to protect these portions from external environmental influences or subsequent etching and removal processes. The shielding pattern 800 may be formed as a pattern including photoresist material. The shielding pattern 800 may be formed by coating, exposing, and developing the photoresist material. The shielding pattern 800 may expose the alignment hole 420 provided by the second phase-shifting pattern 503 and the portion 504 of the second phase-shifting pattern 503 adjacent to the alignment hole 420.

[0066] Reference Figure 10 This allows for the execution of an etching process using the shielding pattern 800 as an etching mask. The second phase-shifting pattern ( Figure 9 The portion 504 of the second phase shift pattern 503 exposed by the shielding pattern 800 can be selectively etched and removed. Thus, the frame pattern 402 can be exposed. When the shielding pattern 800 extends to cover a portion 502 of the second phase shift pattern 503, the portion 502 of the second phase shift pattern 503 can be retained as an edge ring pattern 502.

[0067] The shielding pattern 800 blocks and protects the first phase-shifting pattern 501 and the portions 301 and 303 of the reflective layer 300 that overlap with the first region 101 of the substrate 100 from the etch environment during the selective removal of the second phase-shifting pattern 503 or portions 504 of the second phase-shifting pattern 503. Therefore, during the process of selectively removing the second phase-shifting pattern 503 or portions 504 of the second phase-shifting pattern 503, damage to the first phase-shifting pattern 501 and the portions 301 and 303 of the reflective layer 300 that overlap with the first region 101 of the substrate 100 can be effectively prevented or mitigated. The shielding pattern 800 also effectively prevents or mitigates damage to the portions of the cover layer 310 of the reflective layer 300 that overlap with the first region 101 of the substrate 100.

[0068] The shielding pattern 800 can be selectively removed, and the surface where the shielding pattern 800 has been removed can be cleaned. Through these manufacturing processes, it is possible to achieve... Figure 1 The phase shift mask 10 is shown.

[0069] Various concepts have been disclosed in conjunction with some embodiments described above. Those skilled in the art will understand that various modifications, additions, and substitutions can be made without departing from the scope and spirit of this disclosure. Therefore, the embodiments disclosed in this specification should not be understood in a restrictive manner but rather as illustrative. The scope of the various concepts is not limited to the above description but is defined by the appended claims, and all different features within the equivalent scope should be interpreted as including within these concepts.

[0070] Cross Reference to Related Applications

[0071] This application claims priority to Korean Application No. 10-2021-0077710, filed June 15, 2021, which is incorporated by reference herein in its entirety.

Claims

1. A phase shift mask, the phase shift mask comprising: a reflective layer formed on a substrate; a device pattern formed on the reflective layer; a frame pattern formed on the reflective layer, the frame pattern including an alignment hole exposing a portion of the reflective layer; a phase shift pattern overlapping the device pattern; and an edge ring pattern formed on the frame pattern spaced apart from the phase shift pattern and formed as a pattern in a ring shape surrounding the phase shift pattern, wherein a region of the frame pattern adjacent to the alignment hole is exposed without overlapping the phase shift pattern and the edge ring pattern. The frame pattern has a reflectivity lower than a reflectivity of the reflective layer with respect to a light source of a wavelength of 248 nm to 900 nm.

2. The phase shift mask of claim 1, wherein, The frame pattern has a reflectivity of 50% or less of the reflectivity of the reflective layer with respect to a light source of a wavelength of 248 nm to 900 nm.

3. The phase shift mask of claim 1, wherein, The frame pattern has a reflectivity of 2% to 30% with respect to a light source of a wavelength of 248 nm to 900 nm.

4. The phase shift mask of claim 1, wherein, The frame pattern includes at least one selected from a group consisting of ruthenium Ru, silicon Si, molybdenum Mo, tantalum Ta, titanium Ti, and zirconium Zr.

5. The phase shift mask of claim 1, wherein, The frame pattern includes at least one selected from a group consisting of silicon nitride Si3N4, silicon oxide SiO2, silicon oxynitride SiON, tantalum oxide Ta2O5, titanium oxide TiO2, hafnium oxide HfO2, and zirconium oxide ZrO2.

6. The phase shift mask of claim 1, wherein, The frame pattern and the device pattern include the same material layer.

7. The phase shift mask of claim 1, wherein, The phase shift pattern is formed such that extreme ultraviolet light reflected by the phase shift pattern has a phase difference of 180 degrees to 300 degrees from extreme ultraviolet light reflected by the reflective layer.

8. The phase shift mask of claim 1, wherein, The phase shift pattern includes a phase shift layer including at least one selected from a group consisting of ruthenium Ru, molybdenum Mo, niobium Nb, tantalum Ta, titanium Ti, and zirconium Zr.

9. The phase shift mask of claim 1, wherein, The phase shift layer further includes at least one of carbon C, oxygen O, and nitrogen N.

10. The phase shift mask of claim 9, wherein, The phase shift pattern has a reflectivity of 5% to 60% with respect to extreme ultraviolet.

11. The phase shift mask of claim 1, wherein, The phase shift pattern has a refractive index of 0.87 to 0.96 and an extinction coefficient of 0.005 to 0.04 with respect to extreme ultraviolet.

12. The phase shift mask of claim 1, wherein, The reflective layer includes:

13. The phase shift mask of claim 1, wherein, a multilayer in which first and second reflective layers having different refractive indices with respect to extreme ultraviolet are alternately laminated; and a cover layer covering the multilayer.

14. The phase shift mask according to claim 13, the first reflective layer includes a silicon Si layer, wherein wherein the second reflective layer includes a molybdenum Mo layer, and wherein the cover layer includes a ruthenium Ru layer. The frame pattern is a peripheral edge surrounding the device pattern.

15. The phase shift mask of claim 1, wherein, 16. A method of manufacturing a phase shift mask, the method comprising the steps of: forming a reflective layer on a substrate; forming an underlayer on the reflective layer; forming a phase shift upper layer on the underlayer; patterning a first phase shift pattern from the phase shift upper layer by sequentially etching the phase shift upper layer and the underlayer and patterning a device pattern overlapping the first phase shift pattern and a frame pattern overlapping a second phase shift pattern providing an alignment hole from the underlayer; and ​ selectively removing a portion of the second phase shift pattern to form an edge ring pattern formed on the frame pattern spaced apart from the first phase shift pattern and formed in a ring shape surrounding the first phase shift pattern, wherein a region of the frame pattern adjacent to the alignment hole is exposed without overlapping with the first phase shift pattern and the edge ring pattern.

17. The method of claim 16, further comprising the step of: forming a photoresist pattern on the upper layer for phase shift as an etching mask for etching the upper layer for phase shift and the lower layer.

18. The method of claim 17, further comprising the step of: forming a hard mask layer covering the upper layer for phase shift before forming the photoresist pattern.

19. The method of claim 16, wherein, The step of selectively removing a portion of the second phase shift pattern includes the steps of: forming a shielding pattern exposing the portion of the second phase shift pattern; and selectively removing the portion of the second phase shift pattern exposed through the shielding pattern.

20. The method of claim 19, wherein, The shielding pattern covers the first phase shift pattern, portions of the reflective layer between the first phase shift pattern, portions of the reflective layer between the first phase shift pattern and the second phase shift pattern, and portions of the second phase shift pattern other than the portion.

21. The method of claim 16, wherein, The reflectivity of the lower layer with respect to a light source of a wavelength of 248 nm to 900 nm is lower than the reflectivity of the reflective layer.

22. The method of claim 16, wherein, The reflectivity of the lower layer with respect to a light source of 248 nm to 900 nm is 50% or less of the reflectivity of the reflective layer.

23. The method of claim 16, wherein, The lower layer has a reflectivity of 2% to 30% with respect to a light source of 248 nm to 900 nm.

Images