Method for manufacturing phase-shift mask blank with low refractive index and low extinction coefficient

Abstract

The present invention discloses a method for manufacturing a phase shift mask blank with a low refractive index and a low extinction coefficient, comprising: selecting a phase shift mask blank substrate with a refractive index below 1.6 and an extinction coefficient below 0.05; polishing and cleaning the substrate; stacking a transition layer on the substrate, with the difference between the refractive index n1 of the transition layer and the refractive index n2 of the substrate within 0.3; stacking a phase shift layer on the transition layer, with the differences between the refractive index n3 of the phase shift layer and the refractive index n1 of the transition layer and the refractive index n2 of the substrate respectively within 0.5, and the extinction coefficient k1 of the phase shift layer for light with a wavelength of 190 - 900 nm being below 0.9; stacking a chromium film layer on the phase shift layer; and stacking a photoresist on the chromium film layer. The method for manufacturing a phase shift mask blank provided by the present invention can maintain a low extinction coefficient across the entire wavelength range of 190 - 900 nm, reduce the lithography time under each exposure light source, improve the lithography efficiency, and at the same time ensure that the film thickness of the phase shift film is conducive to the formation of a lithography structure.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor integrated circuit manufacturing, and in particular to a method for manufacturing a phase-shift mask blank with low refractive index and low extinction coefficient. Background Art

[0002] With the rapid development of integrated circuit design, the size of the design graphics is shrinking, the optical proximity effect is becoming more and more obvious, and more and more optical technologies and optical proximity correction technologies are being applied to the photolithography process. In order to ensure the accuracy of the photolithography graphics, the phase shift mask (PSM) technology is increasingly being used. The principle of the phase shift mask is to add a dielectric layer-phase shifter to the transparent pattern of the Mask (mask), so that the phase difference between the light wave and the adjacent transparent mask substrate after passing through the phase shifter is 180°. According to the principle of light interference, two beams of diffracted light with a phase difference of 180° will destructively interfere, thereby eliminating the diffraction effect, reducing the light intensity of the dark field in the light field, and increasing the light field in the bright area to improve the contrast and resolution. The function of the phase shift mask (PSM) is to eliminate the light diffraction at the edge of the pattern to achieve the purpose of improving the resolution of the pattern.

[0003] Usually, the mask phase shift layer film material is composed of silicon oxynitride or molybdenum silicon oxynitride and their single-layer material or multi-layer material. Because the single-layer type is easier to process, it has become the current mainstream processing method. Even if there is a multi-layer structure, it is a simple thickness stacking of the same material. Among them, the thickness and refractive index of the phase shift mask meet the relevant empirical formula:

[0004] d=λ / [2(n+cosθ)]

[0005] Formula d represents the single layer thickness or total thickness of the phase shift layer, λ is the wavelength of the exposure light source, n is the refractive index of the phase shift layer, and θ is the phase angle (phase difference) of the phase shift layer, which is usually 180°±5°. Therefore, the above formula can also be expressed as:

[0006] d = λ / [2(n-1)]

[0007] The main goal of making phase-shift mask blanks is to obtain a phase shift angle of 180°±5° for the blank, so that two beams of diffracted light with a phase difference of 180° will destructively interfere with each other, thereby eliminating the diffraction effect. The refractive index and thickness only need to satisfy this formula. The transmittance, refractive index and extinction coefficient of the film layer are not the main considerations. In addition, there are relatively few requirements for the material composition of the film layer.

[0008] However, in the actual production process, the thickness of the phase shift mask is related to the transmittance of the film layer. The transmittance of the phase shift film layer of the current common phase shift mask is 6%, and the contrast can be increased to 99.8%. When the metal or semi-metal component in the phase shift film layer increases, the transmittance will decrease, the refractive index will increase accordingly, and the thickness of the phase shift film will become very thin, which is not conducive to the formation of the photolithography structure.

[0009] The light source for exposure in phase-shift mask lithography is mainly short-wavelength light sources such as ArF (wavelength 193nm) and KrF (wavelength 248nm). The energy of the light source itself is relatively weak and the exposure time is long. The absorption of the phase-shift mask film layer material needs to be as small as possible, and reducing the absorption of the relevant wavelength of the material is mainly to reduce the extinction coefficient of the film layer.

[0010] Therefore, controlling the low extinction coefficient and low refractive index of the phase-shift mask film material plays an important role in subsequent lithography. Summary of the invention

[0011] In view of the problems of long exposure time and low process tolerance in the current phase-shift mask blank manufacturing method, the present invention provides a method for manufacturing a phase-shift mask blank with a low refractive index and a low extinction coefficient, which can maintain a low extinction coefficient at the full wavelength of 190-900nm, reduce the lithography time under each exposure light source, improve the lithography efficiency, and at the same time ensure that the film thickness of the phase-shift film is conducive to the formation of the lithography structure.

[0012] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0013] A method for manufacturing a phase-shift mask blank with a low refractive index and a low extinction coefficient, the manufacturing method comprising:

[0014] Selecting a phase shift mask blank substrate, wherein the substrate has a refractive index of less than 1.6 and an extinction coefficient of less than 0.05;

[0015] Polishing and cleaning the substrate to ensure that the optical parameters of the substrate do not change;

[0016] A transition layer is stacked on the substrate, wherein the difference between the refractive index n1 of the transition layer and the refractive index n2 of the substrate is within 0.3;

[0017] A phase shift layer is stacked on the transition layer, wherein the difference between the refractive index n3 of the phase shift layer and the refractive index n1 of the transition layer and the refractive index n2 of the substrate is within 0.5, and the extinction coefficient k1 of the phase shift layer for light with a wavelength of 190-900nm is less than 0.9;

[0018] stacking a chromium film layer on the phase-shift layer to form a pattern structure;

[0019] A photoresist layer is stacked on the chromium film layer to complete the production of the phase-shift mask blank.

[0020] According to one aspect of the present invention, the transition layer is a silicon dioxide film layer.

[0021] According to one aspect of the present invention, stacking a transition layer on the substrate specifically includes: using medium frequency magnetron sputtering to perform coating stacking, wherein the required target material is a silicon target, the power of the medium frequency magnetron sputtering is 0.5KW, the sputtering atmosphere is oxygen, and the atomic ratio of silicon and oxygen in the film layer material is 1:1 to 1:3.

[0022] According to one aspect of the present invention, the extinction coefficient of the phase shift layer for light with a wavelength of 365 nm is less than 0.25.

[0023] According to one aspect of the present invention, the refractive index n3 of the phase shift layer is less than 1.9.

[0024] According to one aspect of the present invention, stacking a phase-shift layer on the transition layer specifically includes: using magnetron sputtering to perform film stacking, wherein the required target material is a molybdenum-silicon target, the power of the magnetron sputtering is 1.5KW, the sputtering atmosphere is nitrogen, and the atomic ratio of molybdenum, silicon, and nitrogen in the film material is 1:(2-4):(2-6).

[0025] According to one aspect of the present invention, stacking a phase-shift layer on the transition layer specifically includes: using magnetron sputtering to perform coating stacking, wherein the required target material is a molybdenum-silicon target, the power of the magnetron sputtering is 1.5KW, the sputtering atmosphere is nitrogen, and the atomic ratio of molybdenum, silicon and nitrogen in the film layer material is 1:2:4.

[0026] According to one aspect of the present invention, the chromium film layer includes a light shielding layer and a low reflection layer, which are used to form a pattern structure and protect the phase shift film layer.

[0027] According to one aspect of the present invention, stacking a chromium film layer on the phase-shift layer specifically includes: performing film stacking by magnetron sputtering, wherein the target material required is a chromium target.

[0028] According to one aspect of the present invention, coating the photoresist on the chromium film layer specifically includes: coating the photoresist by central dripping or spin coating.

[0029] The advantages of the present invention are as follows: by adding a transition layer between the substrate and the phase shift layer, the difference between the refractive index of the transition layer and the refractive index of the substrate is controlled within 0.3, and the transition layer is made of a material with optical parameters close to those of the substrate material, and the transition layer can greatly improve the service life of the phase shift film structure layer. The extinction coefficient of the phase shift layer is controlled below 0.9, and the extinction coefficient at the full wavelength of 190-900nm is controlled below 0.9, especially the extinction coefficient at a wavelength of 365nm is below 0.25, which greatly shortens the takt time of subsequent exposure, can effectively increase the time consumed by the exposure process, improve the photolithography efficiency, and greatly reduce the photolithography time under each exposure light source. The atomic ratio of molybdenum: silicon: nitrogen in the phase shift layer film material is 1: (2-4): (2-6), and there is a specific composition with an atomic ratio of molybdenum: silicon: nitrogen of 1: 2: 4, which has high strength and environmental stability and can well solve the problem of poor film tolerance caused by long exposure time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a process flow chart of a method for manufacturing a phase-shift mask blank with a low refractive index and a low extinction coefficient according to the present invention;

[0032] Figure 2 It is a cross-sectional schematic diagram of the phase-shift pickling mold blank of the present invention;

[0033] Figure 3 is a graph showing the extinction coefficient of the phase shift layer of the present invention at different wavelengths;

[0034] Figure 4 The refractive index curves of the substrate of the present invention at different wavelengths.

[0035] In the figure: 11, substrate; 12, transition layer; 13, phase shift layer; 14, chromium film layer; 15, photoresist layer. DETAILED DESCRIPTION

[0036] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described. It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments proposed herein.

[0037] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps of the specific order described. As will be understood by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps of performing them in the order written, and those skilled in the art can easily understand that these sequences can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The light sources conventionally used for exposure in phase-shift mask lithography are mainly short-wavelength light sources such as ArF (wavelength 193nm) and KrF (wavelength 248nm). Unless otherwise specified, the refractive index and extinction coefficient mentioned in this embodiment refer to the refractive index and extinction coefficient values ​​of the film layer under the KrF (wavelength 248nm) light source.

[0040] like Figure 1 and Figure 2 As shown, a method for manufacturing a phase-shift mask blank with a low refractive index and a low extinction coefficient comprises:

[0041] Step 1: Select a phase shift mask blank substrate 11. The refractive index of the phase shift mask blank substrate 11 should be less than 1.6 and the extinction coefficient should be less than 0.05. Preferably, the transmittance of the substrate 11 for light with a wavelength of 248 nm should be greater than 92%;

[0042] like Figure 4As shown, the refractive index curves of different wavelengths of the phase shift mask blank substrate, the horizontal axis is the wavelength, the vertical axis is the refractive index. The refractive index value of 248nm is 1.55, and the 193nm curve reaches a maximum of 1.62.

[0043] In practical applications, transparent quartz glass or organic film can be used as the base material, or other transparent materials that meet the requirements of a refractive index below 1.6, an extinction coefficient below 0.05, and a transmittance above 92% under a wavelength of 248nm can be used as the base material.

[0044] Step 2: Polishing and cleaning the substrate 11, specifically including chemical mechanical polishing, concentrated sulfuric acid cleaning, and ultrasonic cleaning of the substrate 11 to completely remove pollution, metal ion components, oxide film, etc., to ensure that the optical parameters (refractive index, extinction coefficient, transmittance) of the substrate do not change.

[0045] During this process, a person of ordinary skill in the art should understand that the steps of polishing and cleaning the substrate 11 are not limited to the above steps, and other substrate cleaning methods within the technical field may be used, such as chemical cleaning, mechanical cleaning, ultrasonic cleaning, laser cleaning, plasma cleaning, etc. These cleaning methods may be used alone or in combination according to actual needs.

[0046] Step 3: stacking a transition layer 12 on the substrate 11, the difference between the refractive index n1 of the transition layer 12 and the refractive index n2 of the substrate is within 0.3, and the thickness of the transition layer 12 is controlled to be less than 100 angstroms. In this embodiment, the transition layer 12 is a silicon dioxide film layer.

[0047] The phase-shift layer of the phase-shift mask is the main graphic structure layer, which needs to be used many times and is in direct contact with the transparent substrate below. Therefore, it is designed to stack a very thin layer of material with optical parameters close to the substrate material as a transition layer 12, that is, the transition layer 12 is located between the transparent substrate and the phase-shift layer 13. After adding the transition layer 12, the service life of the phase-shift film structure layer can be greatly improved.

[0048] The service life of the phase shift layer is mainly characterized by the adhesion performance between the film layer and the glass substrate. In the photomask substrate industry, the general method of measuring adhesion performance is to tear the film layer with 3M tape and observe the number of new holes after the film layer is torn off under an optical microscope to measure the adhesion performance. The comparison of the number of holes with and without the transition layer after tearing is shown in Table 1 below.

[0049] Number of tearing Number of holes (without transition layer) Number of holes (with transition layer) 0 0 0 200 0 0 400 0 0 600 0 0 800 0 0 1000 0 0 1200 1 0 1400 1 0 1600 2 1 1800 3 2 2000 4 2

[0050] Table 1

[0051] In practical applications, stacking the transition layer 12 on the substrate specifically includes: using medium frequency magnetron sputtering to perform coating stacking, wherein the required target material is a silicon target, the power of the medium frequency magnetron sputtering is 0.5KW, the sputtering atmosphere is oxygen, and the atomic ratio of silicon and oxygen in the film material is 1:1 to 1:3.

[0052] Step 4: stacking a phase shift layer 13 on the transition layer 12, wherein the refractive index n3 of the phase shift layer 13 is less than 1.9, and the difference between the refractive index n3 of the phase shift layer 13 and the refractive index n1 of the transition layer 12 and the refractive index n2 of the substrate is within 0.5.

[0053] If the refractive index of the phase shift layer 13 is too large, the thickness of the phase shift layer 13 will become thinner, which is not conducive to the formation of the structural layer after subsequent exposure. At the same time, the smaller the difference in refractive index between the phase shift layer, the transition layer, and the substrate, the smaller the difference in the propagation speed of light, which can expand the parameter setting range of the subsequent exposure process and improve the process fault tolerance.

[0054] At the same time, the extinction coefficient k1 of the phase shift layer 13 for light with a wavelength of 190-900nm is less than 0.9, especially the extinction coefficient of the phase shift layer for light with a wavelength of 365nm is controlled to be less than 0.25. The characteristics of the phase shift layer film can maintain a low extinction coefficient at the full wavelength of 190-900nm in subsequent exposure, which greatly shortens the tact time of subsequent exposure and can effectively increase the time consumed by the exposure process. The exposure process is the most time-consuming in subsequent products. Secondly, in the production of semiconductor chip products, a chip generally requires dozens of masks. A light source with a wavelength of 436nm or 365nm is used for exposure at the design edge and unimportant areas, and a light source with a wavelength of 248nm is used for exposure in important areas. Therefore, the film material of the phase shift layer can reduce the absorption of light at the wavelength of the exposure light source used, greatly reducing the photolithography time under each exposure light source.

[0055] like Figure 3 As shown, the extinction coefficient curve of the phase shift layer at different wavelengths, the horizontal axis is wavelength, and the vertical axis is extinction coefficient. The lowest point of the extinction coefficient curve is 365nm, and the highest point is 193nm or 520nm, but the highest point is ≤0.9, and the extinction coefficient curve of the entire phase shift layer is ≤0.9.

[0056] In practical applications, stacking the phase shift layer 13 on the transition layer specifically includes: using magnetron sputtering to perform coating stacking, wherein the required target material is a molybdenum-silicon target, the power of the magnetron sputtering is 1.5KW, the sputtering atmosphere is nitrogen, and the atomic ratio of molybdenum, silicon, and nitrogen in the film material is 1:(2-4):(2-6).

[0057] Nitrogen is used as both a ignition gas and a reaction gas, and is the only atmosphere used in the sputtering process. Compared with oxygen, the formed molybdenum silicon nitride has a higher transmittance. Under the condition of controlling the same transmittance of 6%, the film thickness of molybdenum silicon nitride is relatively thicker, and the film layer obtained by molybdenum silicon oxide needs to be made thinner to obtain a transmittance of 6%. Therefore, thinner molybdenum silicon oxide is not conducive to the formation of subsequent graphic structures. At the same time, nitrogen is used as a ignition atmosphere, and the sputtering reaction speed is slower. During the film formation process, the proportion of molybdenum silicon components will be reduced. The increase of molybdenum silicon components will reduce the transmittance of the film layer and reduce the thickness of the film layer.

[0058] Preferably, when the atomic ratio of molybdenum, silicon and nitrogen in the film material is 1:2:4, it has very high strength and environmental stability, and can effectively solve the problem of poor film tolerance caused by long exposure time (a single-layer MoSi2N4 contains 7 atomic layers of N-Si-N-Mo-N-Si-N, which is composed of two Si-N layers sandwiching a single-layer MoN (N-Mo-N), and the maximum fracture strength of a single-layer MoSi2N4 is 15GPa).

[0059] Step 5: stacking a chromium film layer 14 on the phase-shift layer 13, wherein the chromium film layer 14 includes a light shielding layer and a low-reflection layer, which are used to form a graphic structure during wet etching and protect the underlying phase-shift film layer.

[0060] In practical applications, stacking a chromium film layer on the phase shift layer specifically includes: using magnetron sputtering to stack the coating, wherein the target material required is a chromium target. The remaining operation process is a conventional operation scheme in the technical field, which belongs to the existing known technology, and is not described in detail in this specification.

[0061] Step 6: Dehydrate and dry the substrate and the film layer with IPA. The specific operation method of the IPA dehydration and drying technology does not belong to the necessary protection features of the present invention and belongs to the existing known technology, so it will not be described in detail here.

[0062] Step 7: stacking a photoresist layer 15 on the chromium film layer 14, the photoresist can be an electron beam photoresist or a conventional photoresist such as 248nm or 436nm, and the photoresist is coated by central glue dripping and spin coating. After coating, pre-baking is performed to complete the production of the phase shift mask blank.

[0063] Embodiment 1:

[0064] (1) Quartz glass is selected as the substrate material. The transmittance of the material is more than 90% under a light source with a wavelength of 200nm, more than 92% under a light source with a wavelength of 248nm, more than 94% under a light source with a wavelength of 365nm, and more than 94% under a light source with a wavelength of 436nm. The refractive index is 1.55 and the extinction coefficient is 0 under a light source with a wavelength of 248nm.

[0065] (2) The quartz glass was cleaned with SPM at a concentration of 98%, and then ultrasonically cleaned; the transmittance of the quartz glass substrate was measured again, which was 92% under a light source with a wavelength of 248nm and 94% under a light source with a wavelength of 365nm. The refractive index was 1.57 and the extinction coefficient was 0 under a light source with a wavelength of 248nm.

[0066] (3) Transition layer sputtering coating. On the magnetron sputtering coating machine, a medium frequency magnetron sputtering power supply is used, and single target position double target sputtering is adopted. Silicon target is selected as the target material, the sputtering pressure is 0.2Pa, the sputtering power is 0.5KW, the sputtering atmosphere is oxygen, and the atomic ratio of silicon and oxygen in the transition film layer is 1:2.

[0067] The transition layer was tested by an ellipsometer and the film thickness was 10 nanometers. The refractive index was 1.57 and the extinction coefficient was 0.02 under a light source with a wavelength of 248 nm. The transition layer was stacked on a quartz glass substrate.

[0068] (4) Sputtering coating of phase-shift layer. In the magnetron sputtering coating machine, a DC magnetron sputtering power supply is used, a single target and a single target position are used, a molybdenum-silicon target is selected as the target material, the sputtering pressure is 0.17 Pa, the sputtering power is 1.5 KW, the sputtering atmosphere is nitrogen, and the atomic ratio of molybdenum, silicon and nitrogen in the phase-shift layer is 1:2:4.

[0069] The phase shift layer was tested by ellipsometer and the film thickness was 95 nanometers. The refractive index was 1.85 and the extinction coefficient was 0.81 under a light source with a wavelength of 248 nm. The extinction coefficient was 0.89 under a light source with a wavelength of 190 nm. The extinction coefficient was 0.25 under a light source with a wavelength of 365 nm. The extinction coefficient was 0.28 under a light source with a wavelength of 900 nm. The highest extinction coefficient was 0.9 at a wavelength of 190-900 nm.

[0070] After measurement, the transmittance of the phase shift layer under a light source with a wavelength of 248nm is 5.8%.

[0071] The phase shift layer is stacked above the transition layer.

[0072] (5) Sputtering coating of chromium film layer. In the magnetron sputtering coating machine, a DC magnetron sputtering power supply is used, a single target and a single target position are used, and a chromium target is selected as the target material. First, a layer of light-shielding chromium film is stacked, and then a layer of low-reflection chromium film is stacked. The sputtering pressure is 0.2-0.35Pa, the sputtering power is 3.5-4.5KW, and the sputtering atmosphere contains argon, oxygen, carbon dioxide, and nitrogen. The chromium film layer is a mixture of chromium nitride and oxidized chromium.

[0073] The optical parameters of the chromium film layer are as follows: OD, 3.2; reflectivity is 14% under a wavelength of 436nm light source, and thickness is 110nm. The chromium film layer is stacked on the phase shift layer, and the low reflection layer is located on the light shielding layer.

[0074] (6) The combination of the substrate and the film layer is subjected to IPA ultrasonic cleaning to remove the floating dust on the surface, and the film layer is dehydrated and dried to increase the adhesion.

[0075] (7) A layer of IP3500 photoresist is stacked on the chrome film layer, and the coating is applied by central glue dripping and spin coating, with a coating thickness of 4800 Å. A hot plate is used for pre-baking, with a baking temperature of 130 degrees and a baking time of 15 minutes.

[0076] Embodiment 2:

[0077] (1) Organic film is selected as the base material. The transmittance of the material is more than 88% under a light source with a wavelength of 200nm, more than 90% under a light source with a wavelength of 248nm, more than 92% under a light source with a wavelength of 365nm, and more than 92% under a light source with a wavelength of 436nm. The refractive index is 1.58 and the extinction coefficient is 0.03 under a light source with a wavelength of 248nm.

[0078] (2) After ultrasonic cleaning, the transmittance of the film was measured again and found to be above 90% under a light source with a wavelength of 248nm and above 92% under a light source with a wavelength of 365nm. The refractive index under a light source with a wavelength of 248nm was 1.60 and the extinction coefficient was 0.05.

[0079] (3) Transition layer sputtering coating. On the magnetron sputtering coating machine, a medium frequency magnetron sputtering power supply is used, single target position double target sputtering is adopted, silicon target is selected as the target material, the sputtering pressure is 0.5Pa, the sputtering power is 1.0KW, the sputtering atmosphere is oxygen and argon, and the atomic ratio of silicon and oxygen in the transition film layer is 1:3.

[0080] The transition layer was tested by an ellipsometer and the film thickness was 15 nanometers. The refractive index was 1.75 and the extinction coefficient was 0.06 under a light source with a wavelength of 248 nm. The transition layer was stacked on a film substrate.

[0081] (4) Phase-shift layer sputtering coating. In the magnetron sputtering coating machine, a medium-frequency magnetron sputtering power supply is used, a single target and a single target position are used, a molybdenum-silicon target is selected as the target material, the sputtering pressure is 0.35Pa, the sputtering power is 0.8KW, the sputtering atmosphere is nitrogen and argon, and the atomic ratio of molybdenum, silicon and nitrogen in the phase-shift layer is 1:4:4.

[0082] The phase shift layer was tested by ellipsometer and had a film thickness of 85 nanometers. The refractive index was 1.9 and the extinction coefficient was 0.85 under a light source with a wavelength of 248 nm. The extinction coefficient was 0.88 under a light source with a wavelength of 190 nm. The extinction coefficient was 0.24 under a light source with a wavelength of 365 nm and 0.30 under a light source with a wavelength of 900 nm. The highest extinction coefficient was 0.9 at 190-900 nanometers.

[0083] After measurement, the transmittance of the phase shift layer under a light source with a wavelength of 248nm is 5.5%.

[0084] The phase shift layer is stacked above the transition layer.

[0085] (5) Sputtering coating of chromium film layer. In the magnetron sputtering coating machine, a DC magnetron sputtering power supply is used, a single target and a single target position are used, and a chromium target is selected as the target material. First, a layer of light-shielding chromium film is stacked, and then a layer of low-reflection chromium film is stacked. The sputtering pressure is 0.2-0.35Pa, the sputtering power is 3.5-4.5KW, and the sputtering atmosphere contains argon, oxygen, carbon dioxide, and nitrogen. The chromium film layer is a mixture of chromium nitride and oxidized chromium.

[0086] The optical parameters of the chromium film layer are as follows: OD, 3.5; reflectivity 9% under a wavelength of 436nm light source, thickness 950nm. The chromium film layer is stacked on the phase shift layer, and the low reflection layer is located on the light shielding layer.

[0087] (6) The combination of the substrate and the film layer is subjected to IPA ultrasonic cleaning to remove the floating dust on the surface, and the film layer is dehydrated and dried to increase the adhesion.

[0088] (7) A layer of AZ1500 photoresist is stacked on the chromium film layer, and the coating is applied by central glue dripping and spin coating, with a coating thickness of 5000 Å. A hot plate is used for pre-baking, the baking temperature is 120 degrees, and the baking time is 20 minutes.

[0089] Advantages of the implementation of the present invention: 1. The smaller the difference in refractive index between the phase shift layer, the transition layer, and the substrate, the smaller the difference in light propagation speed, which can expand the parameter setting range of the subsequent exposure process and improve the process fault tolerance.

[0090] 2. The characteristics of the phase shift layer film of the present application can maintain a low extinction coefficient at the full wavelength of 190-900nm in subsequent exposure, which greatly shortens the takt time of subsequent exposure and can effectively improve the time consumed in the exposure process.

[0091] 3. It can solve the problem of poor film tolerance caused by long exposure time.

[0092] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for manufacturing a phase-shift mask blank with a low refractive index and a low extinction coefficient, characterized in that: The production method comprises: Selecting a phase shift mask blank substrate, wherein the substrate has a refractive index of less than 1.6 and an extinction coefficient of less than 0.05; Polishing and cleaning the substrate; A transition layer is stacked on the substrate, wherein the transition layer is a silicon dioxide film layer, and the difference between the refractive index n1 of the transition layer and the refractive index n2 of the substrate is within 0.3; A phase shift layer is stacked on the transition layer, wherein the difference between the refractive index n3 of the phase shift layer and the refractive index n1 of the transition layer and the refractive index n2 of the substrate is within 0.5, and the extinction coefficient k1 of the phase shift layer for light with a wavelength of 190-900nm is less than 0.9; stacking a chromium film layer on the phase-shift layer to form a pattern structure; A photoresist layer is stacked on the chromium film layer to complete the production of the phase-shift mask blank.

2. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: Stacking the transition layer on the substrate specifically includes: using medium frequency magnetron sputtering to perform coating stacking, wherein the required target material is a silicon target, the power of the medium frequency magnetron sputtering is 0.5KW, the sputtering atmosphere is oxygen, and the atomic ratio of silicon and oxygen in the film material is 1:1~1:

3.

3. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: The extinction coefficient of the phase shift layer for light with a wavelength of 365 nm is less than or equal to 0.

25.

4. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: The refractive index n3 of the phase shift layer is less than 1.

9.

5. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: Stacking the phase-shift layer on the transition layer specifically includes: using magnetron sputtering to perform coating stacking, wherein the required target material is a molybdenum-silicon target, the power of the magnetron sputtering is 1.5KW, the sputtering atmosphere is nitrogen, and the atomic ratio of molybdenum, silicon and nitrogen in the film material is 1: (2-4): (2-6).

6. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: Stacking the phase-shift layer on the transition layer specifically includes: performing film stacking by magnetron sputtering, wherein the required target material is a molybdenum-silicon target, the power of the magnetron sputtering is 1.5KW, the sputtering atmosphere is nitrogen, and the atomic ratio of molybdenum, silicon and nitrogen in the film material is 1:2:

4.

7. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: The chromium film layer includes a light shielding layer and a low reflection layer, which are used to form a graphic structure and protect the phase shift film layer.

8. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: Stacking a chromium film layer on the phase-shift layer specifically includes: performing film stacking by magnetron sputtering, wherein the target material required is a chromium target.

9. The method for manufacturing a phase shift mask blank according to claim 1, characterized in that: Stacking a photoresist layer on the chromium film layer specifically includes: coating the photoresist by central dripping or spin coating.

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