Photomask blank, photomask, and method for manufacturing semiconductor device

Abstract

Embodiments relate to a photomask blank, a photomask, a method of manufacturing a semiconductor device, and the like, and provide a photomask blank or the like including a light-transmissive substrate, and a multilayer light-blocking film disposed on the light-transmissive substrate; the light-blocking film includes a first light-blocking layer having a first hardness, and a second light-blocking layer having a second hardness; the first light-blocking layer is disposed closer to the light-transmissive substrate than the second light-blocking layer, and the first hardness is a value greater than the second hardness. The photomask blank, photomask, or the like of embodiments has improved defect resistance, and further reduces the occurrence of defects with high precision in a method of manufacturing a semiconductor device.

Description

TECHNICAL FIELD

[0001] One embodiment relates to a photomask blank and a photomask having improved performance. Another embodiment relates to a method of manufacturing a semiconductor device, which further reduces defects by high precision. BACKGROUND

[0002] With high integration of semiconductor devices and the like, there is a demand for miniaturization of circuit patterns of semiconductor devices. As a result, the importance of photolithography technology, which is a technology of developing a circuit pattern on a wafer surface using a photomask, is more emphasized.

[0003] In order to develop a miniaturized circuit pattern, there is a demand for shortening of a wavelength of an exposure light source used in an exposure process. Recently, an exposure light source such as an ArF excimer laser (wavelength of 193 nm) is used.

[0004] On the other hand, photomasks include a binary mask and a phase shift mask.

[0005] The binary mask has a structure in which a light-blocking layer pattern is formed on a light-transmissive substrate. The binary mask, on a side on which the pattern is formed, transmits exposure light through a transmission portion not including the light-blocking layer, and blocks the exposure light through a light-blocking portion including the light-blocking layer, thereby exposing a pattern on a resist film on a wafer surface. However, in the binary mask, as a pattern is more miniaturized, a problem in developing a fine pattern can occur due to diffraction of light generated at an edge of the transmission portion in the exposure process.

[0006] The phase shift mask includes a Levenson type, an outrigger type, and a half-tone type. Among them, the half-tone type phase shift mask has a structure in which a pattern formed of a semi-transmissive film is formed on a light-transmissive substrate. The half-tone type phase shift mask, on a side on which the pattern is formed, transmits exposure light through a transmission portion not including the semi-transmissive layer, and transmits attenuated exposure light through a semi-transmissive portion including the semi-transmissive layer. The attenuated exposure light has a phase difference compared to the exposure light transmitted through the transmission portion. As a result, diffraction light generated at an edge of the transmission portion is canceled by the exposure light transmitted through the semi-transmissive portion, and the phase shift mask can form a finer fine pattern on a wafer surface.

[0007] Related prior art includes Korean Patent Laid-Open No. 10-2012-0121333, Korean Patent No. 10-1308838, and the like. SUMMARY

[0008] Problems to be Solved

[0009] One embodiment provides a photomask blank and a photomask with improved performance. Another embodiment provides a method for manufacturing a semiconductor device, further reducing the generation of defects through high precision.

[0010] Solution to the problem

[0011] To achieve the above-mentioned objective, a photomask blank according to one embodiment includes: a light-transmitting substrate; and a multi-layer light-shielding film disposed on the light-transmitting substrate.

[0012] The light-shielding film includes a first light-shielding layer having a first hardness and a second light-shielding layer having a second hardness. The first light-shielding layer may be disposed closer to the light-transmitting substrate than the second light-shielding layer.

[0013] The first hardness may be greater than the second hardness.

[0014] The second hardness may be 0.15 to 0.55 times the first hardness.

[0015] The second hardness may be 0.3 kPa to 0.55 kPa.

[0016] The Young's modulus of the second light-shielding layer may be greater than or equal to 1.0 kPa.

[0017] A photomask blank of another embodiment includes: a transparent substrate and a multi-layer light-shielding film disposed on the transparent substrate; the light-shielding film includes: a first light-shielding layer having a first hardness, and a second light-shielding layer disposed on the first light-shielding layer and having a second hardness.

[0018] The second hardness may be 0.3 kPa to 0.55 kPa.

[0019] The thickness ratio of the first light-shielding layer to the second light-shielding layer may be 1:0.02 to 0.25.

[0020] The light-shielding film may have a transmittance of 1 or more with respect to a wavelength of 193 nm.

[0021] The Young's modulus of the second light-shielding layer may be greater than or equal to 1.0 kPa.

[0022] A photomask blank according to another embodiment includes a transparent substrate and a multi-layered light-shielding film disposed on the transparent substrate. The light-shielding film includes a first light-shielding layer having a first hardness and a second light-shielding layer disposed on the first light-shielding layer and having a second hardness. The first light-shielding layer may be disposed closer to the transparent substrate than the second light-shielding layer.

[0023] The first hardness may be greater than the second hardness.

[0024] The second hardness can be 0.15 to 0.55 times the first hardness.

[0025] The second hardness can be 0.3 to 0.55 kPa.

[0026] The second light-blocking layer can have a Young's modulus of 1.0 kPa or more.

[0027] Another embodiment of a photomask blank includes a light-transmissive substrate, and a multilayered patterned light-blocking film disposed on the light-transmissive substrate. The patterned light-blocking film includes a patterned first light-blocking layer having a first hardness, and a patterned second light-blocking layer disposed on the first light-blocking layer and having a second hardness.

[0028] The second hardness can be 0.55 kPa or less.

[0029] The second hardness can be 0.3 to 0.55 kPa.

[0030] The thickness ratio of the first light-blocking layer to the second light-blocking layer can be 1:0.02 to 0.25.

[0031] The light-blocking film can have a transmittance of 1 or more with respect to a 193 nm wavelength.

[0032] The second light-blocking layer can have a Young's modulus of 1.0 kPa or more.

[0033] A method of manufacturing a semiconductor device includes a preparation step of preparing a target substrate, and a patterning step of applying a photomask to a surface of the target substrate and performing patterning to manufacture a patterned target substrate.

[0034] The photomask is the photomask described above.

[0035] To achieve the above object, an embodiment of a photomask blank includes a light-transmissive substrate, and a multilayered light-blocking film disposed on the light-transmissive substrate.

[0036] The light-blocking film includes a first light-blocking layer having a first Young's modulus, and a second light-blocking layer having a second Young's modulus. The first light-blocking layer can be disposed closer to the light-transmissive substrate than the second light-blocking layer.

[0037] The first Young's modulus can be a value greater than the second Young's modulus.

[0038] The second Young's modulus can be 0.15 to 0.55 times the first Young's modulus.

[0039] The second Young's modulus can be 1.0 to 4.2 kPa.

[0040] The second light-shielding layer can have a hardness of 0.55 kPa or less.

[0041] The photomask blank of another embodiment includes a light-transmissive substrate, and a multi-layered light-shielding film disposed on the light-transmissive substrate; the light-shielding film includes a first light-shielding layer having a first Young's modulus, and a second light-shielding layer disposed on the first light-shielding layer and having a second Young's modulus.

[0042] The second Young's modulus can be 1.0 kPa or more.

[0043] The second light-shielding layer can have a thickness of 30 nm or more.

[0044] The second light-shielding layer can have a standard deviation of adhesion force measured at 16 different positions that is 8% or less of an average value of the adhesion force.

[0045] The second light-shielding layer can have a standard deviation of separation force measured at 16 different positions that is 5% or less of an average value of the separation force.

[0046] The photomask blank of another embodiment includes a light-transmissive substrate, and a multi-layered light-shielding film disposed on the light-transmissive substrate; the light-shielding film includes a first light-shielding layer having a first Young's modulus, and a second light-shielding layer disposed on the first light-shielding layer and having a second Young's modulus. The first light-shielding layer can be disposed closer to the light-transmissive substrate than the second light-shielding layer.

[0047] The first Young's modulus can be greater than the second Young's modulus.

[0048] The second Young's modulus can be 0.15 to 0.55 times the first Young's modulus.

[0049] The second Young's modulus can be 1.0 kPa to 4.2 kPa.

[0050] The second light-shielding layer can have a hardness of 0.55 kPa or less.

[0051] The photomask blank of another embodiment includes a light-transmissive substrate, and a multi-layered patterned light-shielding film disposed on the light-transmissive substrate; the patterned light-shielding film includes a patterned first light-shielding layer having a first Young's modulus, and a patterned second light-shielding layer disposed on the first light-shielding layer and having a second Young's modulus.

[0052] The first Young's modulus can be greater than the second Young's modulus.

[0053] The second Young's modulus can be 1.0 kPa or more.

[0054] The second Young's modulus may be 0.15 to 0.55 times the first Young's modulus.

[0055] The second Young's modulus may be 1.0 kPa to 4.2 kPa.

[0056] The hardness of the second light-shielding layer may be less than 0.55 kPa.

[0057] A method for manufacturing a semiconductor device according to another embodiment includes: a preparation step of preparing a target substrate; and a patterning step of applying a photomask to a surface of the target substrate and performing patterning to manufacture a patterned target substrate.

[0058] The photomask described above is applicable to the photomask.

[0059] Effects of the Invention

[0060] A photomask blank according to an embodiment of the present invention employs a light-shielding film with adjusted hardness, thereby providing a photomask blank that reduces the degree of defects caused by particles while maintaining other performance at or above the same level.

[0061] The photomask of another embodiment can provide a photomask that reduces the occurrence of defects caused by particles and further improves the light shielding effect even when a pattern with a finer line width is applied.

[0062] A method for manufacturing a semiconductor device according to another embodiment uses the above-mentioned photomask to manufacture a semiconductor device with fewer defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a conceptual diagram illustrating a cross-sectional structure of a photomask blank according to an embodiment.

[0064] Figure 2 This is a conceptual diagram illustrating the structure of a photomask according to one embodiment through a cross section.

[0065] Figure 3 This is a conceptual diagram illustrating a cross-sectional structure of a photomask blank according to another embodiment.

[0066] Figure 4 This is a conceptual diagram illustrating the structure of a photomask according to still another embodiment through a cross section.

[0067] Figure 5 yes Figure 2 An enlarged conceptual diagram of part A.

[0068] Figure 6A and Figure 6B The cross section of the comparative example and the particle formation Figure 6A A magnified conceptual diagram of part A.

[0069] Figure 7A and Figure 7B The following are photographs showing examples of formation of scratching particles in Comparative Examples 1 and 2 of the experimental examples (results after applying a high-frequency filter (HF filter) in the inspection machine).

[0070] Description of Reference Numerals

[0071] 100: Photomask blank 300: Photomask

[0072] 10: Transparent substrate 20: Phase shift film

[0073] 23: Patterned phase shift film 30: Light shielding film

[0074] 33: Patterned light-shielding film 301: First light-shielding layer

[0075] 302: second light shielding layer 331: patterned first light shielding layer

[0076] 332: Patterned second light shielding layer P: particles DETAILED DESCRIPTION

[0077] The following embodiments are described in detail so that those skilled in the art can easily implement the embodiments. However, the embodiments can be implemented in many different forms and are not limited to the embodiments described herein.

[0078] When inherent manufacturing and material tolerances are set forth in the meaning mentioned, the terms "about", "substantially" and the like used in this specification are used to mean from or close to its numerical value to prevent unscrupulous infringers from improperly exploiting the disclosed content, that is, content that mentions exact or absolute numerical values ​​to assist in understanding the embodiments.

[0079] Throughout this 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 multiple structural elements described in the Markush form expression, and means including one or more selected from the group consisting of the above multiple structural elements.

[0080] Throughout this specification, the term "A and / or B" means "A, B, or A and B."

[0081] Throughout this specification, terms such as “first”, “second”, “A”, “B” and the like are used to distinguish the same terms from each other unless otherwise specified.

[0082] In this specification, B is located on A means that B is located on A, or B is located on A while other layers are located therebetween, and is not limited to the manner in which B is connected to the surface of A.

[0083] In this specification, unless otherwise specified, a singular expression may include a singular or plural meaning as interpreted by the context.

[0084] For the purpose of properly illustrating the concept of the embodiments, the drawings in this specification may be exaggerated, and the embodiments are not limited by the drawings.

[0085] In this specification, the exposure wavelength is described as 193 nm ArF wavelength, but unless otherwise specified, the scope of rights of the embodiments should not be interpreted as being limited to application to the above wavelength.

[0086] As semiconductor devices become increasingly integrated, increasingly fine circuit patterns need to be formed on semiconductor substrates. As the line width of patterns developed on semiconductor substrates becomes increasingly fine, more stringent control of defects caused by particles is required.

[0087] Photomasks used to form patterns in semiconductor devices must have excellent resolution. Unlike display photomasks, semiconductor photomasks, where the pattern is magnified, require stricter conditions for resolution and defects. In a cross section, it is ideal that the top corners of the pattern (at Figure 2 The photomask (represented by A in the figure) is substantially formed at a right angle, but it is difficult to form it completely at a right angle in reality. In particular, particles originating from corners and the like may be formed during the etching process of the photomask, and these particles may act as scratching particles of the photomask. That is, the particles may damage the substrate or pattern during the etching, cleaning and other processes, which may eventually lead to defects in the pattern of the photomask and the semiconductor pattern manufactured thereby. The inventors have confirmed that forming the light-shielding film of the photomask into a structure with more than two layers and controlling the hardness and other properties between the layers can substantially suppress the generation of particles, and have proposed embodiments.

[0088] Figure 1 and Figure 3 are conceptual diagrams illustrating the structures of photomask blanks according to one embodiment and another embodiment through cross sections, respectively. Figure 2 and Figure 4 The schematic diagrams are conceptual diagrams illustrating the cross-section structures of photomasks according to one embodiment and another embodiment. Figure 5 for Figure 2 The enlarged conceptual diagram of part A of Figures 1 to 5 , which describes the embodiments in more detail.

[0089] Photomask blank 100 and photomask 300

[0090] To achieve the above objectives, a photomask blank 100 according to one embodiment includes: a transparent substrate 10 ; and a multi-layered light shielding film 30 disposed on the transparent substrate.

[0091] The light shielding film 30 includes a first light shielding layer 301 having a first hardness and a second light shielding layer 302 having a second hardness.

[0092] The first light shielding layer 301 is disposed closer to the light-transmitting substrate 10 than the second light shielding layer.

[0093] The photomask blank 100 may further include a phase shift film 20 disposed between the transparent substrate 10 and the light shielding film 30 .

[0094] The photomask blank 100 may further include a hard coating layer (not shown) disposed on the light shielding film 30 .

[0095] The photomask blank 100 may further include a hard coating layer (not shown) on the light shielding film 30 and a photoresist film (not shown) on the hard coating layer.

[0096] To achieve the above objectives, a photomask 300 according to an embodiment includes: a transparent substrate 10 ; and a multi-layer patterned light shielding film 33 disposed on the transparent substrate.

[0097] The patterned light shielding film 33 includes a patterned first light shielding layer 331 having a first hardness and a patterned second light shielding layer 332 having a second hardness.

[0098] The patterned first light shielding layer 331 is disposed closer to the transparent substrate 10 than the patterned second light shielding layer 332 .

[0099] The photomask 300 may further include a patterned phase shift film 23 disposed between the transparent substrate 10 and the patterned light shielding film 33 .

[0100] The photomask 300 may further include a hard coating layer (not shown) disposed on the patterned light shielding film 33. The hard coating layer is also referred to as a hard mask layer and may be a patterned layer.

[0101] The patterned light-shielding film and the patterned phase-shifting film may be formed by patterning the light-shielding film and the phase-shifting film of the photomask blank, respectively.

[0102] The light-shielding film 30 has the property of blocking at least a predetermined portion of incident exposure light. Furthermore, when a phase shift film 20 or the like is provided between the transparent substrate 10 and the light-shielding film 30, during the process of etching the phase shift film 20 or the like according to the pattern shape, the light-shielding film 30 has different etching characteristics from adjacent films such as the phase shift film, thereby also functioning as an etching mask.

[0103] 在实施例中,遮光膜30包括:图案化的第一遮光层331,具有第一硬度;以及图案化的第二遮光层332,具有第二硬度。

[0104] Hereinafter, unless otherwise specified, the description of the patterned light-shielding film, the patterned first light-shielding layer, the patterned second light-shielding layer, etc. is directly applicable to the description of the light-shielding film, the first light-shielding layer, the second light-shielding layer, etc.

[0105] The first hardness may be greater than the second hardness.

[0106] The second light shielding layer is located on the upper portion of the light shielding film. The first light shielding layer is located on the lower portion of the light shielding film. In this case, the hardness of the second light shielding layer can be a value smaller than the hardness of the first light shielding layer.

[0107] The second light-shielding layer is located away from the transparent substrate. In this case, the second light-shielding layer is located farther from the transparent substrate relative to the first light-shielding layer. In this case, the hardness of the second light-shielding layer can be less than the hardness of the first light-shielding layer.

[0108] By making the hardness of the second light-shielding layer smaller than that of the first light-shielding layer, the frequency of particle generation due to the partial disappearance of the light-shielding film can be reduced, and the possibility of scratches caused by particles can be significantly reduced. In addition, the size of the generated particles is also smaller than that of a single layer of light-shielding film, which can further suppress the generation of scratching particles (see Figure 5 、 Figure 6A and Figure 6B ).

[0109] The second hardness may be 0.15 to 0.55 times the first hardness. The second hardness may be 0.2 to 0.4 times the first hardness. When the second hardness is less than 0.15 times the first hardness, the etching speed may be slowed down in the etching process using an etchant such as a chlorine gas. When the second hardness is greater than 0.55 times the first hardness, the effect of reducing the possibility of damage caused by particles may become negligible. When the second hardness is 0.2 to 0.4 times the first hardness, the possibility of a decrease in the etching characteristics of the light-shielding film due to an increase in optical density can be minimized, and the effect of reducing the possibility of damage caused by particles can be fully obtained.

[0110] The second hardness may be 0.55 kPa or less. The second hardness may be 0.3 kPa to 0.55 kPa. The second hardness may be 0.42 kPa to 0.52 kPa. The second hardness may be 0.45 kPa to 0.51 kPa. Within this range, the first light-shielding layer can provide the entire light-shielding film with suitable optical properties while also effectively suppressing scratches caused by particles.

[0111] The first hardness can be between 1 kPa and 3 kPa. The first hardness can be between 1.1 kPa and 2.5 kPa. The first hardness can be between 1.3 kPa and 2.5 kPa. When the first hardness falls within this range, the light-shielding film as a whole can have appropriate transmittance, optical density, and etching properties, and can be particularly well-suited for light sources with a wavelength of 193 nm.

[0112] The first light shielding layer 301 may have a first Young's modulus.

[0113] The second light shielding layer 302 may have a second Young's modulus.

[0114] The first Young's modulus may be greater than the second Young's modulus.

[0115] The second light-shielding layer is located at the upper portion of the light-shielding film. The first light-shielding layer is located at the lower portion of the light-shielding film. In this case, the Young's modulus of the second light-shielding layer may be smaller than that of the first light-shielding layer.

[0116] The second light-shielding layer is located away from the transparent substrate. In this case, the second light-shielding layer is located farther from the transparent substrate relative to the first light-shielding layer. In this case, the Young's modulus of the second light-shielding layer can be smaller than that of the first light-shielding layer.

[0117] By making the Young's modulus of the second light-shielding layer smaller than that of the first light-shielding layer, the frequency of particle generation due to partial disappearance of the light-shielding film can be reduced, and the possibility of scratches caused by particles can be significantly reduced.

[0118] The second Young's modulus may be 0.15 to 0.55 times the first Young's modulus, 0.20 to 0.45 times the first Young's modulus, or 0.23 to 0.42 times the first Young's modulus.

[0119] When the second Young's modulus is less than 0.15 times the first Young's modulus, the etching rate may be slowed in etching processes using etchants such as chlorine-based gases. When the second Young's modulus is greater than 0.55 times the first Young's modulus, the effect of reducing particle generation may become negligible. When the second Young's modulus is between 0.2 and 0.45 times the first Young's modulus, the degradation of etching characteristics can be minimized in etching processes using etchants such as chlorine-based gases, while fully achieving the effect of reducing the possibility of damage caused by particles.

[0120] The second Young's modulus may be greater than 1.0 kPa. The second Young's modulus may be between 1.0 kPa and 4.2 kPa. The second Young's modulus may be between 1.2 kPa and 3.7 kPa. The second Young's modulus may be between 2.3 kPa and 3.5 kPa. Within this range, the first light-shielding layer can provide the entire light-shielding film with suitable etching properties while also appropriately suppressing particle generation.

[0121] The first Young's modulus may be 7 kPa to 13 kPa. The first Young's modulus may be 7.3 kPa to 12 kPa. The first Young's modulus may be 8 kPa to 11.8 kPa. When the first Young's modulus is within this range, the light-shielding film as a whole can have appropriate transmittance, optical density, and etching properties, and is particularly well-suited for use with a light source having a wavelength of 193 nm.

[0122] The above-mentioned hardness and the above-mentioned Young's modulus can be measured using an atomic force microscope (AFM). Specifically, an AFM device of Park System (equipment model XE-150) is used, the scanning speed is set to 0.5 Hz, and the contact mode and cantilever model are applied using Park System's PPP-CONTSCR measurement. The adhesion of 16 points in the object to be measured is measured, and the average value is taken. The hardness or Young's modulus value thus obtained is used as the above-mentioned hardness or Young's modulus value. The measuring tip used in the measurement is a Berkovich tip (Poisson's ratio of the tip: 0.07) for silicon raw materials. The hardness and Young's modulus measurement results use the values ​​obtained by the program provided by the AFM equipment company using the Oliver and Pharr Model.

[0123] The above measurement can also provide the separation force, adhesion force, etc. The separation force and / or adhesion force measured at 16 different locations have a small overall deviation in the measured values, which means that the physical properties of the light shielding film are uniform across all the measurement locations.

[0124] The standard deviation of the adhesion energy measured at 16 different locations on the second light-shielding layer 302 (preferably at locations spaced at least 1 cm apart) can be less than 8%, less than 6%, or less than 5% of the average adhesion energy. The standard deviation can be at least 0.001% of the average adhesion energy. Even when a photomask blank 100 or photomask 300 having such characteristics is formed with a fine pattern as a whole, particle formation can be uniformly suppressed, and the formation of scratches caused by particles can be reduced.

[0125] The adhesion of the second light shielding layer 302 may be greater than 0.25 fJ, greater than 0.30 fJ, or less than 0.4 fJ.

[0126] Light-shielding film 30 and patterned light-shielding film 33

[0127] In an embodiment, the light shielding film 30 may be located on the top surface of the transparent substrate 10. Regarding the light shielding film 30, on the side facing the bottom surface of the transparent substrate 10, the adhesion of the second light shielding layer 302 may be greater than that of the first light shielding layer 301 by at least 0.10 fJ. The adhesion of the second light shielding layer 302 may be greater than that of the first light shielding layer 301 by no more than 0.15 fJ.

[0128] The standard deviation of the pull-off force measured at 16 different locations on the second light-shielding layer 302 can be less than 5%, less than 3%, or less than 2% of the average pull-off force. The standard deviation can be at least 0.001% of the average pull-off force. Even when a photomask blank 100 or photomask 300 having such characteristics is formed with a fine pattern as a whole, the formation of particles can be uniformly suppressed, and the formation of scratches caused by particles can be reduced.

[0129] The separation force of the second light shielding layer 302 may be greater than 4.0 nN. The separation force of the second light shielding layer 302 may be greater than 4.1 nN. The separation force of the second light shielding layer 302 may be less than 4.8 nN.

[0130] The separation force of the second light shielding layer 302 may be greater than the separation force of the first light shielding layer 301 by 0.6 nN or more. The separation force of the second light shielding layer 302 may be greater than the adhesion force of the first light shielding layer 301 by 1.2 nN or less.

[0131] The first light-shielding layer 301 and the second light-shielding layer 302 may have a thickness ratio of 1:0.02 to 0.25. The first light-shielding layer 301 and the second light-shielding layer 302 may have a thickness ratio of 1:0.04 to 0.18. The light-shielding film 30 comprising both the first and second light-shielding layers can meet requirements for transmittance and optical density, while also reducing the generation of particles and scratches.

[0132] The thickness of the second light shielding layer 302 may be 30 nm to 80 nm. The thickness of the second light shielding layer 302 may be 40 nm to 70 nm. When the second light shielding layer is formed with such a thickness, the effect of reducing particle formation can be more excellent.

[0133] The thickness or thickness ratio can be confirmed by layer differentiation using a microscopic photograph of a cross section, and any method can be applied without limitation as long as the thickness can be confirmed.

[0134] The transmittance of the light-shielding film 30 at a wavelength of 193 nm may be greater than 1, and may be greater than 1.33. The transmittance of the light-shielding film 30 at a wavelength of 193 nm may be greater than 1.38, and may be greater than 1.4. The transmittance of the light-shielding film 30 at a wavelength of 193 nm may be less than 1.6.

[0135] The optical density of the light shielding film 30 with respect to a wavelength of 193 nm may be 2.0 or less, or 1.87 or less, or 1.8 or more, or 1.83 or more.

[0136] The optical density of the laminate including the light shielding film 30 and the phase shift film 20 may be 3.0 or higher.

[0137] When the light-shielding film has such transmittance and optical density, it can provide a desired excellent light-shielding effect to the photomask or the photomask blank.

[0138] The first light-shielding layer 301 and the second light-shielding layer 302 each contain a metal element in the layer.

[0139] The metal may be a transition metal, and the transition metal may include one selected from the group consisting of Cr, Ta, Ti, and Hf. More specifically, the first light shielding film 30 and / or the second light shielding film 30 may include chromium.

[0140] The metal contained in the first light-shielding layer 301 or the second light-shielding layer 302 imparts light-shielding properties depending on its content, while also affecting physical properties such as hardness. However, these physical properties can vary depending on various factors, including the density of the light-shielding layer, the degree of crystallization of the elements contained in the light-shielding layer, the content of non-metallic elements in the light-shielding layer, and the arrangement of the various structural elements within the light-shielding layer.

[0141] The second light-shielding layer 302 may have a higher metal content than the first light-shielding layer 301. However, controlling properties such as hardness and Young's modulus is not limited to this; rather, it is necessary to satisfy the overall optical and etching properties required for the photomask. Therefore, simply increasing the metal content may make it difficult to control the overall physical properties.

[0142] The difference in the physical properties such as the hardness of the second light-shielding layer 302 and the first light-shielding layer 301 can be adjusted by the content of the metal described above, and also by the ratio of the content of the inactive gas used in the sputtering process for deposition, the ratio of the reactive gases used to form the first light-shielding layer and the second light-shielding layer, and the like. The details will be described later.

[0143] Other thin films

[0144] As described above, the phase shift film, the hard mask, the photoresist film, and the like can be applied to the photomask blank or the photomask.

[0145] The photomask blank 100 can be sequentially stacked with the light-transmissive substrate 10, the phase shift film 20, the light-shielding film 30, the photoresist film (not shown), and the like, and a hard mask (not shown) can also be disposed between the light-shielding film and the photoresist film.

[0146] The phase shift film 20 can be located between the light-transmissive substrate 10 and the light-shielding film 30. The phase shift film 20 functions to attenuate the light intensity of the exposure light transmitted through the phase shift film 20, and substantially suppresses the diffracted light generated at the edges of the transferred pattern by adjusting the phase difference.

[0147] The light-transmissive substrate 10 can have a transmittance of 85% or more with respect to the exposure light having a wavelength of 193 nm. The transmittance can be 87% or more. The transmittance can be 99.99% or less. Illustratively, the light-transmissive substrate 10 can be a synthetic quartz substrate. In this case, the light-transmissive substrate 10 can suppress the attenuation of the light transmitted through the light-transmissive substrate 10. However, as a raw material for the light-transmissive substrate 10, any material having light-transmissive properties with respect to the exposure light and applicable to the photomask 300 can be used.

[0148] The phase shift film 20 can have a phase difference of 170° to 190° with respect to light having a wavelength of 193 nm. The phase shift film 20 can have a phase difference of 175° to 185° with respect to light having a wavelength of 193 nm. The phase shift film 20 can have a transmittance of 3% to 10% with respect to light having a wavelength of 193 nm. The phase shift film 20 can have a transmittance of 4% to 8% with respect to light having a wavelength of 193 nm. In this case, the resolution of the photomask 300 including the phase shift film 20 can be improved.

[0149] The phase shift film 20 can include a transition metal and silicon. The phase shift film 20 can include a transition metal, silicon, oxygen, and nitrogen. The transition metal can be molybdenum.

[0150] The description of the patterned phase shift film 23 directly applies to the description of the phase shift film 20 described above.

[0151] The hard mask (not shown) functions to suppress the pattern collapse phenomenon in which the photoresist film collapses when etching the pattern. Also, the hard mask can function as an etching mask during the patterning of the light-shielding film 30.

[0152] The hard mask may include one selected from silicon, nitrogen, and oxygen. For example, the hard mask may be SiON, SiN, etc., but is not limited thereto.

[0153] Application and manufacturing

[0154] The photomask 300 is formed by patterning the above-mentioned photomask blank 100 according to the desired design, and the patterning process involves at least several etching and cleaning steps. For example, the desired pattern is formed on the photoresist film by exposure and development, and the hard mask is exposed by selective etching. Thereafter, an etchant with a relatively large selectivity is applied to the hard mask and the light-shielding film, and predetermined portions are removed according to the design of the hard mask and the light-shielding film. At this time, the phase shift film can also be removed by changing the etchant. Thereafter, part or all of the hard mask and the light-shielding film can be removed as needed, and the etchant is also applied in the removal process. The etchant is selectively applied according to the characteristics of each film. In dry etching, fluorine-based etchants, chlorine-based etchants, etc. can be selectively used by mixing with reactive gases (oxygen, etc.) or inactive gases (nitrogen, helium, etc.). In addition, the etchant is removed in each etching step, and a cleaning process can also be performed to confirm whether the etching degree is appropriate. In this process, there is a possibility that foreign matter will be generated in the form of unexpected particles due to external impact (for example, physical impact caused by the cleaning liquid, etc.) on the non-constant parts such as the cleaning liquid or the density of the film, or chemical damage caused by the etchant, or their interaction, and scratch defects based on this may also be generated.

[0155] The photomask blanks and / or photomasks of the embodiments utilize multiple layers of light-shielding film, adjust the physical properties of the two layers positioned above and below each other, and control the hardness and / or Young's modulus of the upper light-shielding film. This reduces the generation of foreign matter such as particles during development and cleaning processes, and even if particles do occur, the resulting scratch defects can be minimized. Furthermore, this advantage is achieved while maintaining the optical, thickness, and etching properties of the light-shielding film at or above a certain level.

[0156] Hereinafter, a method for producing the light-shielding film will be described.

[0157] The manufacturing method of the light-shielding film includes: a preparation step of setting a substrate and a sputtering target in a sputtering chamber; a film-forming step of injecting atmospheric gas into the sputtering chamber and applying electricity to the sputtering target to form a light-shielding film on the substrate; a heat treatment step of heat-treating the formed light-shielding film to control residual stress and stabilize it; and a cooling step of cooling the stabilized light-shielding film.

[0158] The above-mentioned substrate can be applied to a light-transmitting substrate or a substrate with a phase shift film deposited on a light-transmitting substrate.

[0159] The film forming step includes: a first film forming process to form a first light-shielding layer; and a second film forming process to form a second light-shielding layer on the first light-shielding layer.

[0160] The first film forming process and the second film forming process are sequentially performed to form the first light shielding layer and the second light shielding layer, respectively, using a metal target and an atmospheric gas.

[0161] As the metal target, in reactive sputtering, a target of a desired metal can be used. For example, when chromium is used as the transition metal, a chromium target can be used.

[0162] The atmosphere gas may be selected according to the required composition, thickness, density, etc. of the first light-shielding layer and / or the second light-shielding layer, and may be a mixture of an inert gas and a reactive gas.

[0163] As the inert gas, argon, helium, etc. can be used alone or in combination. The inert gas is involved in the deposition process during sputtering and is removed in subsequent heat treatment, etc., which is related to the control of film density.

[0164] As the reactive gas, gases containing nitrogen, oxygen, or the like can be used alone or in combination. Carbon dioxide can also be used as needed. Examples of such reactive gases include, but are not limited to, CO2, O2, N2, NO, NO2, N2O, N2O3, N2O4, and N2O5. The amount of such gases used can influence the composition of the film, the degree of elemental bonding within the film, the degree of etching, and the degree of particle formation.

[0165] The first atmosphere gas used as the atmosphere gas for the first film formation process can be a low-molecular-weight inert gas such as argon or helium. When a low-molecular-weight inert gas such as helium is used as the inert gas in addition to argon, it can help control the density of the manufactured light-shielding layer. The first atmosphere gas can contain a reactive gas, and the reactive gas can be a gas containing nitrogen, oxygen, etc. as described above. The content of the reactive gas in the first atmosphere gas is correlated with the content of the reactive gas in the second atmosphere gas described later, which can more effectively control the hardness, Young's modulus, etc.

[0166] Argon is used as the second atmospheric gas in the second film-forming process, serving as an inert gas. To adequately control hardness and other factors, low-molecular-weight inert gases such as helium are not used alone. However, hardness and other factors can be adjusted by adjusting the content of reactive gases.

[0167] The ratio of the reactive gas content in the second atmosphere gas to the reactive gas content in the first atmosphere gas can be 0.7 to 1.1 by volume, 0.8 to 1.05 by volume, or 0.85 to 0.95 by volume. Using the reactive gases at these volume ratios makes it easier to control the hardness, Young's modulus, and other properties of the first and second light-shielding layers.

[0168] The power source used in the sputtering process may be a direct current (DC) power source or a radio frequency (RF) power source. The power used in the sputtering process may be 0.5 kW to 5.0 kW.

[0169] The sputtering time in the first film forming process and the second film forming process may be applied at a ratio of 100:7 to 32. In this case, a light-shielding film having a desired appropriate thickness ratio can be obtained.

[0170] The heat treatment step uniformly heats the entire substrate, removing residual stress that may have been generated during the sputtering process and further alleviating whipping of the photomask blank. The temperature during the heat treatment step can be between 150°C and 330°C. Excluding the heating time, the heat treatment can last for approximately 5 to 50 minutes.

[0171] The cooling step can be performed by air cooling to a temperature of 10° C. to 30° C., and the air cooling can be performed using an inert gas or dry air.

[0172] The light-shielding film 30 manufactured by the above-described method includes a first light-shielding layer 301 and a second light-shielding layer 302 , each of which contains at least one of a transition metal, oxygen, and nitrogen.

[0173] The second light-shielding layer 302 may contain 50 to 80 atomic percent (at%) of a transition metal. The second light-shielding layer 302 may contain 55 to 75 atomic percent of a transition metal. The second light-shielding layer 302 may contain 60 to 70 atomic percent of a transition metal. The total oxygen and nitrogen content of the second light-shielding layer 302 may be 10 to 30 atomic percent. The total oxygen and nitrogen content of the second light-shielding layer 302 may be 15 to 25 atomic percent. The second light-shielding layer 302 may contain 5 to 15 atomic percent of nitrogen. The second light-shielding layer 302 may contain 7 to 13 atomic percent of nitrogen.

[0174] The first light-shielding layer 301 may contain 30 to 60 atomic percent of a transition metal. The first light-shielding layer 301 may contain 31 to 55 atomic percent of a transition metal, or may contain 35 to 55 atomic percent. The first light-shielding layer 301 may contain 40 to 50 atomic percent of a transition metal. The total oxygen and nitrogen content of the first light-shielding layer 301 may be 40 to 70 atomic percent. The total oxygen and nitrogen content of the first light-shielding layer 301 may be 45 to 65 atomic percent. The total oxygen and nitrogen content of the first light-shielding layer 301 may be 50 to 60 atomic percent. The first light-shielding layer 301 may contain 20 to 37 atomic percent of oxygen. The first light-shielding layer 301 may contain 23 to 33 atomic percent of oxygen. The first light-shielding layer 301 may contain 25 to 30 atomic percent of oxygen. The first light-shielding layer 301 may contain 20 to 35 atomic percent of nitrogen. The first light-shielding layer 301 may contain 26 atomic % to 33 atomic % of nitrogen. The first light-shielding layer 301 may contain 26 atomic % to 30 atomic % of nitrogen.

[0175] The transition metal may include at least one of Cr, Ta, Ti, and Hf. The transition metal may be Cr.

[0176] The phase shift film, the hard mask, the photomask, and the like can be manufactured by conventional manufacturing methods, and the method is not particularly limited.

[0177] Method for manufacturing semiconductor device

[0178] By using the photomask described above, a semiconductor device with fewer defects can be manufactured.

[0179] A method for manufacturing a semiconductor device according to an embodiment includes a preparation step and a patterning step. The preparation step is a step of preparing a target substrate to be patterned.

[0180] The target substrate may be a wafer, a substrate with a conductive layer or an insulating layer formed on a wafer, a glass substrate, etc., but is not limited thereto.

[0181] The patterning step is a step of applying a photomask to a surface of the target substrate and manufacturing a patterned target substrate through a photolithography process. The photolithography process can be a conventional photolithography process, specifically, a photolithography process using a 193 nm ArF light source.

[0182] Specifically, a light source, a photomask positioned in the light path of the light source, and a target substrate including a photoresist film are provided. Light emitted from the light source and passing through the photomask is transmitted to the photoresist film on the target substrate. The light changes the properties of the photoresist film on the target substrate, and a pattern is formed on the target substrate through processes such as development.

[0183] The patterned target substrate has a fine wiring pattern of a semiconductor raw material through repeated processes such as formation of a conductive layer, planarization, and formation of an insulating layer, and can be manufactured into a semiconductor device.

[0184] In the above-mentioned method for manufacturing a semiconductor device, the above-described embodiments can be applied to obtain a pattern with fewer defects, thereby effectively manufacturing a semiconductor device of excellent quality.

[0185] The following examples are provided for further explanation. The following examples are merely for illustrative purposes only and are not intended to limit the scope of the present invention.

[0186] Manufacturing Example: Manufacturing of Light-Shielding Film

[0187] On a synthetic quartz transparent substrate of 6 inches in width, 6 inches in length, and 0.25 inches in thickness, the same substrate having the same phase shift effect of about 180° relative to a wavelength of 193 nm was set to be suitable for the manufacture of the following light-shielding film.

[0188] The substrate was placed in the chamber of a DC sputtering system with a chromium target at a T / S distance of 255 mm and a 25° angle between the substrate and target. The power required to form the first light-shielding layer was 1.85 kWh, and the power required to form the second light-shielding layer was 1.5 kWh.

[0189] While rotating the substrate, sputtering was performed using the following atmosphere gas as shown in Table 1 to sequentially form a first light-shielding layer and a second light-shielding layer, thereby forming a light-shielding film. Heat treatment was performed at 200°C for 15 minutes. After the heat treatment, the light-shielding film was cooled in dry air at 20°C for 5 minutes.

[0190] Table 1

[0191]

[0192]

[0193] #The ratio (volume ratio) of the reactive gas used when forming the second light-shielding layer based on the reactive gas used when forming the first light-shielding layer.

[0194] * The reactive gas 43 is N2 and CO2 at a volume ratio of 11 and 32, respectively.

[0195] *The reactive gas 47 was applied with N2and CO2at a volume ratio of 11 and 36, respectively.

[0196] *The reactive gas 53 was applied with N2and CO2at a volume ratio of 24 and 29, respectively.

[0197] *The reactive gas was applied with N2for the second light-shielding layer.

[0198] Experimental Example: Evaluation of Physical Properties such as Hardness and Young's Modulus

[0199] Hardness, Young's modulus, separation force, and adhesion were measured using an AFM. Using an AFM device of Park Systems (device model XE-150), the scanning speed was set to 0.5 Hz, the contact mode was applied, and the cantilever model was PPP-CONTSCR of Park Systems. Adhesion and the like were measured at 16 points in the object to be measured, and the average value was taken. The hardness or Young's modulus value thus obtained was taken as the above-mentioned hardness or Young's modulus value, and is shown in Table 3 below. The measured data at 16 points in Example 2 are shown in Table 2. The measurement tip applied at the time of measurement was a Berkovitch tip of silicon raw material (Poisson's ratio of the tip: 0.07), and the hardness and Young's modulus measurement results were values obtained using a program provided by the AFM device company, which applies the Oliver and Pharr Model.

[0200] Table 2

[0201]

[0202] *The standard deviation was applied with the STDEV.S function of EXCEL.

[0203] Optical properties were measured by a conventional method using an ellipsometer, and the overall transmittance and optical density of the light-shielding film were shown in Table 3 below together with information such as hardness and Young's modulus.

[0204] The etching ratio was measured by a conventional dry etching method using a chlorine-based gas under the same conditions.

[0205] Table 3

[0206]

[0207] *The hardness ratio is the ratio of the hardness of the second light-shielding layer to that of the first light-shielding layer.

[0208] *The Young's modulus ratio is the ratio of the Young's modulus of the second light-shielding layer to that of the first light-shielding layer.

[0209] Comparative Example 1 shows a single-layer light-shielding film with uncontrolled hardness and other properties. Numerous particles formed during the cleaning process, etc., and attention was paid to damage at the edges and corners of the light-shielding film pattern as one of the contributing factors. Controlling the hardness and Young's modulus, etc., suppressed the generation of these particles, and even if particles did occur, they did not damage the photomask. Because the light-shielding film of a photomask must maintain the required optical properties while also possessing properties such as hardness that reduce particle generation, even with an excessive metal content in the second light-shielding layer, as in Comparative Example 2, the effect of controlling the hardness was minimal, resulting in a negligible improvement in particle reduction. Excessively reducing the hardness of the second light-shielding layer made it difficult to control etching characteristics. Examples 1 to 3 confirmed that it was possible to achieve the desired control effects of hardness, Young's modulus, etc. while maintaining appropriate etching characteristics.

[0210] In particular, in Example 2, it was confirmed that the entire film had constant physical properties, and the particle reduction effect and particle scratch reduction effect were the best. In the comparative example, as the scratch defect evaluation results, the inspection results of the inspection machine (using a high-frequency filter to inspect the image) are shown as an example. Figure 7A and Figure 7B middle. Figure 7A The inspection result of Comparative Example 1 shows that large scratching particles are generated and multiple particles are produced. Figure 6A and Figure 6B As shown in the schematic diagram, the size of the generated particles is large, which also easily causes scratching particles. Figure 7B This is the inspection result of Comparative Example 2. It was confirmed that although the size and number of scratching particles were reduced, the frequency of particle generation was still high.

[0211] The preferred embodiments of the present invention are described in detail above, but the scope of the present invention is not limited thereto. Various modifications and improvements made by ordinary technicians in the technical field of the present invention using the basic concepts of the present invention defined in the attached claims also fall within the scope of the present invention.

Claims

1. A photomask blank, characterized in that include: a light-transmitting substrate, and A multi-layer light-shielding film is located on the light-transmitting substrate; The above-mentioned light-shielding film includes: a first light shielding layer having a first hardness, and The second light shielding layer has a second hardness; The first light-shielding layer is arranged closer to the light-transmitting substrate than the second light-shielding layer. The value of the first hardness is greater than the value of the second hardness, The second hardness is 0.15 to 0.55 times the first hardness.

2. The photomask blank according to claim 1, wherein The second hardness is 0.3 kPa to 0.55 kPa.

3. The photomask blank according to claim 1, wherein The second light-shielding layer has a Young's modulus of 1.0 kPa or more.

4. The photomask blank according to claim 1, wherein The standard deviation of the adhesion of the second light-shielding layer measured at 16 different locations is 8% or less of the average value of the adhesion.

5. The photomask blank according to claim 1, wherein The thickness ratio of the first light-shielding layer to the second light-shielding layer is 1:0.02 to 1:0.

25.

6. The photomask blank according to claim 1, wherein The light-shielding film has a transmittance of 1 or more with respect to a wavelength of 193 nm.

7. The photomask blank according to claim 1, wherein The light-shielding film has an optical density of 1.8 or more at a wavelength of 193 nm.

8. A photomask, characterized in that: include: a light-transmitting substrate, and A multi-layer patterned light-shielding film is located on the transparent substrate; The patterned light-shielding film includes: The patterned first light shielding layer has a first hardness, and The patterned second light shielding layer has a second hardness smaller than the first hardness; The patterned first light-shielding layer is arranged closer to the light-transmitting substrate than the patterned second light-shielding layer. The second hardness is 0.15 to 0.55 times the first hardness.

9. A method for manufacturing a semiconductor device, characterized in that: include: a preparation step, preparing the target substrate, and a patterning step of applying a photomask to a surface of the target substrate and performing patterning to produce a patterned target substrate; The photomask is the photomask according to claim 8 .

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