Photomask protective film frame and preparation method thereof

Abstract

The embodiment of the invention relates to the field of photomasks, and provides a photomask protective film frame and a preparation method thereof, the photomask protective film frame comprises a frame main body made of a metal material and a coating formed on the surface of the frame main body, and the photomask protective film frame is characterized in that the coating is at least composed of carbon black, silicon dioxide particles and organic dye. The nanoscale carbon black in the coating has a high light absorption coefficient, fills gaps of dye molecules and forms a continuous light absorption network, the organic dye enhances absorption of light with specific wavelength through a molecular structure conjugated system, and the nanoscale carbon black and the organic dye form a composite function of broad-spectrum absorption and accurate waveband adjustment, so that more than 95% of light is absorbed in a broad-waveband range, light reflection on the surface of the frame is reduced, and the light absorption efficiency is improved. Pattern distortion caused by reflected light in the photoetching process is avoided, silicon dioxide is embedded into an organic dye matrix, silicon dioxide gaps are filled with carbon black particles, the porosity of the coating is reduced, the wear resistance of the coating is improved, and the cracking risk of the coating is reduced. Optical absorption, wear resistance and weather resistance are synchronously improved.

Description

Technical Field

[0001] The present disclosure relates to the field of photomasks, and in particular to a photomask protective film frame and a preparation method thereof. The photomask protective film frame can absorb more than 95% of light within a wide wavelength range, reduce light reflection on the frame surface, avoid pattern distortion caused by reflected light during the photolithography process, and also has high stability. Background Art

[0002] In the manufacture of semiconductor integrated circuits such as integrated circuits (ICs), large-scale integrated circuits (LSIs), or liquid crystal displays (LCDs), exposure processes such as photolithography are usually used to create patterns. In modern photolithography technology, photomasks are essential molds in the photolithography process. They use the patterns on the mask to transplant the patterns on the mask onto the wafer through processes such as exposure, development, and etching. Therefore, any defects on the photomask will have a significant impact on the chip's yield. As semiconductor devices become more highly integrated, the size of the patterns formed on the wafer continues to decrease. In order to form such fine patterns, finer, higher-quality, and more stable photomasks are required. To protect the photomask from particle contamination and physical damage, a thin, transparent protective film is typically installed on the surface of the photomask. This film is located on the patterned side of the photomask to prevent the pattern on the photomask from being scratched by contaminants. A protective film frame supporting the protective film is attached to the photomask used for photolithography to maintain the flatness and shape stability of the protective film. The frame and film together form a sealed microenvironment to prevent particles, molecular contaminants, or dust in the air from directly contacting the photomask surface. Furthermore, during the exposure process of a photolithography machine, any unnecessary reflected or scattered light (called stray light) in the optical path can degrade image quality, leading to pattern distortion or reduced resolution. Currently, the industry commonly uses black organic dyes (primarily azo dyes, anthraquinone dyes, and phthalocyanine dyes) or inorganic dyes (such as carbon-based materials) to color the frame. This absorbs excess light reflected from the frame surface and reduces the interference of stray light on the optical path. However, due to their insufficient photostability and poor temperature resistance, black organic dyes are prone to absorbing heat and decomposing into gases at high temperatures during long-term photolithography. These gases undergo photochemical reactions with hydrocarbons and ammonia accidentally produced during the photolithography process, resulting in haze or fine particle pollution. Inorganic dyes are also brittle and easy to fall off.

[0003] Therefore, it is necessary to provide a mask protective film frame and a mask with high stability and strong light absorption ability to solve the problems of insufficient light stability, poor temperature resistance and high brittleness and easy falling off of the internal coating dye of the existing mask protective film frame.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0005] In order to solve the defects in the prior art, the present disclosure provides a photomask protective film frame and a preparation method thereof, wherein the photomask protective film frame includes a frame body made of a metal material and a coating formed on the surface of the frame body, wherein the coating is composed of at least carbon black, silica particles and organic dyes. Carbon black and organic dyes have strong light absorption capabilities and can effectively absorb visible light and light in other wavelengths to reduce reflection. At the same time, by adding silica particles in different proportions, the refractive index of the coating can be adjusted, the hardness of the coating can be increased, and the wear resistance and scratch resistance can be improved, which helps to optimize the light reflectivity and reduce the impact of reflected light on photolithography. In addition, the coating has good overall weather resistance, can remain stable at higher temperatures, will not decompose or deform, and is suitable for applications in high temperature environments. At the same time, the coating also provides an additional protective layer for the metal frame body. The coating has strong adhesion and good adhesion to the metal substrate, which avoids peeling of the coating due to thermal expansion and contraction or other external forces during use.

[0006] According to some embodiments of the present disclosure, on one hand, a photomask protective film frame is provided, comprising a frame body made of a metal material and a coating formed on the surface of the frame body, wherein the coating is composed of at least carbon black, silica particles and organic dyes.

[0007] In some embodiments, the metal is one of aluminum, titanium, aluminum alloy, titanium alloy, and stainless steel.

[0008] In some embodiments, the organic dye is one of aniline black and copper phthalocyanine.

[0009] In some embodiments, the coating has a thickness of 5 to 100 μm.

[0010] In some embodiments, the mass ratio of the organic dye, carbon black, and silica particles in the coating is 5-20:10-40:70-90, the carbon black particle size is 5-50 nm, and the silica particle size is 5-100 nm.

[0011] In some embodiments, the coating further includes a binder, and the binder is one of PVDF, epoxy resin, silicone resin, polyimide, and KH550.

[0012] In some embodiments, an aluminum oxide layer is further provided on the coating layer, and the thickness of the aluminum oxide layer is 2-50 nm.

[0013] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure also provides a method for preparing a photomask protective film frame, wherein the photomask protective film frame includes a frame body made of a metal material and a coating formed on the surface of the frame body. The preparation method includes using a metal material to make the frame body; and depositing a coating composed of carbon black, silica particles and organic dyes on the frame body.

[0014] In some embodiments, the metal is one of aluminum, titanium, aluminum alloy, titanium alloy, and stainless steel; the organic dye is one of aniline black and copper phthalocyanine; the mass ratio of the organic dye, carbon black, and silica particles in the coating is: 5~20:10~40:70~90, the carbon black particle size is 5~50nm, and the silica particle size is 5~100nm.

[0015] In some embodiments, the coating has a thickness of 5 to 100 μm, and the coating further comprises a binder, which is one of PVDF, epoxy resin, silicone resin, polyimide, and KH550.

[0016] In some embodiments, an aluminum oxide layer is further provided on the coating layer, and the thickness of the aluminum oxide layer is 2-50 nm.

[0017] In some embodiments, the coating is prepared by a sol-gel method, an electrophoretic deposition method, or a screen printing method.

[0018] According to some embodiments of the present disclosure, another aspect of the present disclosure further provides a photomask protective film, comprising a photomask protective film frame and a protective film adhered to an upper surface of the frame.

[0019] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: The nano-scale carbon black in the coating has a high absorption coefficient and can absorb energy in the ultraviolet-visible light band, reducing light reflection on the surface of the mask frame and avoiding pattern distortion caused by reflected light during the photolithography process. Organic dyes enhance the absorption of light of specific wavelengths through the conjugated system of the molecular structure. Among them, aniline black covers the entire visible light band, and copper phthalocyanine significantly absorbs light from 600-700nm. It can form a composite function of "broad-spectrum absorption + precise band adjustment" with carbon black. At the same time, carbon black fills the gaps between dye molecules to form a continuous light-absorbing network, which increases the light absorption rate of the coating to more than 95% in the wide wavelength range of 193nm-700nm, which is 50% lower than the reflectivity of a single dye coating, ensuring the precise transmission of photolithography light source energy.

[0020] Nano-sized silica particles serve as a hard phase, embedded within an organic dye matrix to form a "ceramic-organic" composite structure. This provides over three times greater wear resistance than pure organic coatings, resisting frictional damage during mask handling. Carbon black particles fill the gaps between the silica particles, reducing coating porosity. They also enhance interfacial bonding with the dye molecules through π-π conjugation, reducing the risk of coating cracking and improving structural stability. The ultra-thin coating prevents thermal expansion coefficient mismatch on the mask frame caused by excessively thick coatings, ensuring uniform light field distribution at the mask edge and meeting sub-14nm process requirements. The specific ratios of carbon black, silica, and organic dye allow the carbon black to form continuous light-absorbing channels, while the silica particles are closely spaced, creating a dense, wear-resistant framework. The dye molecules hydrogen-bond to the silica surface hydroxyl groups, resulting in a coating with adhesion exceeding 5 N / cm, ensuring long-term resistance to detachment. Furthermore, the binder's functional groups (such as epoxy and silanol groups) react with the metal surface hydroxyl groups to form chemical bonds, further enhancing bonding strength compared to binderless coatings.

[0021] Furthermore, when an aluminum oxide layer is applied to the coating surface, the atomically deposited aluminum oxide layer can fill nanoscale defects on the coating surface, forming a chemically inert barrier that further enhances corrosion resistance. Furthermore, the high refractive index of aluminum oxide can adjust the reflectivity of the coating surface, achieving an optimal balance between light absorption and reflection. The thermal stability of the aluminum oxide layer further enhances the stability and service life of the coating. This breaks through the single-function limitations of existing photomask frames and achieves simultaneous improvements in optical absorption, wear resistance, and weather resistance.

[0022] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0024] Figure 1 This is a cross-sectional view of a photomask protective film frame in some embodiments of the present application; Figure 2 This is a cross-sectional view of a photomask protective film frame in some embodiments of the present application; Figure 3 A top view of a photomask protective film frame in some embodiments of the present application; Figure 4 is a schematic diagram of a photomask in some embodiments of the present application.

[0025] Explanation of the accompanying drawings: 1-transparent substrate; 2-mask pattern; 3-adhesive; 4-mask protective film frame; 5-protective film; 6-frame body; 7-coating; 8-aluminum oxide layer. DETAILED DESCRIPTION

[0026] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent identical or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the figures are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0027] Although relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used herein for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It will be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via the other structure.

[0028] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first" and "second" are used only as labels and do not limit the quantity of their objects.

[0029] According to some embodiments of the present disclosure, a photomask protective film frame 4 is provided in combination with Figure 1 、 Figure 3 The pellicle frame 4 includes a frame body 6 made of a metal material and a coating 7 formed on the surface of the frame body 6. The coating is composed of at least carbon black, silica particles, and an organic dye. The pellicle frame 4 corresponds to the shape of the photomask to which it is attached and generally has a quadrilateral frame shape (rectangular frame shape or square frame shape).

[0030] The material of the frame body 6 can be, for example, metal, metalloid, metal oxide, metal nitride, glass, organic-inorganic composite, polymer, ceramic (such as SiC), carbon steel, engineering plastics (such as PE, PA, PEEK), carbon fiber composite materials (such as GFRP, CFRP), etc. The metal can include, for example, copper (Cu), aluminum (Al), stainless steel, nickel (Ni), zinc (Zn), iron (Ti), titanium (Ti), gold (Au), silver (Ag), platinum (Pt), or alloys thereof. Preferably, it can be one of aluminum, aluminum alloy (JIS 5000 series, JIS 6000 series, JIS 7000 series, etc.), titanium, titanium alloy, and stainless steel.

[0031] Before coating, the surface of the frame body is preferably roughened by sandblasting or chemical polishing. For example, the surface of the metal frame body can be sandblasted with stainless steel, corundum, glass beads, etc., or chemically polished with an alkaline solution such as sodium hydroxide solution.

[0032] The organic dye is either aniline black or copper phthalocyanine. Aniline black absorbs the entire visible light band, while copper phthalocyanine significantly absorbs light between 600 and 700 nm. The mass ratio of the organic dye, carbon black, and silica particles in the coating is 5-20:10-40:70-90. The carbon black particles have a size of 5-50 nm, and the silica particles have a size of 5-100 nm. The silica can be purchased directly or prepared using tetraethyl orthosilicate (TEOS) as a silicon source. For example, tetraethyl orthosilicate (TEOS) and ethanol are mixed in a 1:3 volume ratio, 0.1 M hydrochloric acid is added as a catalyst, and the mixture is stirred at 60°C for 2 hours to form a silica sol. Carbon black and the organic dye are then added to form a composite sol, which is then applied to form a coating containing the three components. Nano-scale carbon black, with its high surface area and light absorption properties, effectively absorbs energy from the UV-visible wavelength range, reducing light reflection from the mask frame surface and preventing pattern distortion caused by reflected light during the photolithography process. It also forms a complex function with organic dyes, combining broad-spectrum absorption and precise wavelength tuning, achieving strong absorption across a wide wavelength range and reducing light scattering and reflection. Furthermore, carbon black fills the gaps between dye molecules, forming a continuous light-absorbing network. This increases the coating's light absorption to over 95%, reducing the reflectivity of a single-dye coating by 50%, ensuring precise energy transfer from the photolithography light source. Nano-scale silica particles, embedded as a hard phase in the coating, achieve a Vickers hardness of 200-300 HV, offering wear resistance over three times greater than that of pure organic coatings, effectively resisting frictional damage during mask handling. The nano-scale silica particles synergize with the carbon black, reducing coating porosity and strengthening interfacial bonding with dye molecules, reducing the risk of cracking and improving structural stability. In some embodiments, the coating thickness is 5 to 100 μm. Such an ultra-thin coating design can match the high-precision requirements of the mask frame, avoid the mismatch of thermal expansion coefficients caused by excessively thick coatings, ensure that the frame deformation during the lithography process is ≤5 nm, and meet the process technology requirements below 14 nm.

[0033] In some embodiments, the coating further comprises a binder selected from the group consisting of PVDF, epoxy resin, silicone resin, polyimide, and KH550. The choice of binder depends on the coating preparation method and is not a required component. For example, a binder is not required when depositing the coating using electrophoretic deposition, but is essential when using screen printing. The binder acts as a "molecular bridge" connecting the coating components to the metal substrate, and its properties directly impact the coating's adhesion, cohesion, and long-term stability. It can form covalent bonds with the oxide film on the metal surface through functional groups (such as epoxy groups and silane coupling agents). For example, the epoxy groups of epoxy resin react with the hydroxyl groups on the surface of aluminum oxide to form ether bonds (-O-), with a bonding strength of 5-10 MPa. The flexible structure of the binder's polymer chains can disperse internal stress generated by temperature fluctuations in the coating (such as laser heating during photolithography), preventing cracking. The fluorocarbon segments (-CF2-CF2-) of PVDF are highly flexible and can absorb tensile stresses of 20-50 MPa. They improve the compatibility of inorganic particles such as carbon black and silica with organic dyes, preventing phase separation and promoting the dissolution and dispersion of organic dyes. The amount of binder added is not limited, as long as the coating can be effectively formed. The amount can be 1% to 10% of the total weight of carbon black, silica particles, and organic dyes.

[0034] In some embodiments, an aluminum oxide layer is further provided on the coating. Figure 2The aluminum oxide layer has a thickness of 2-50nm. This aluminum oxide layer is grown on the coating surface using atomic layer deposition (ALD) or chemical vapor deposition (CVD) processes. Its formation involves precursor decomposition and densification: using trimethylaluminum (TMA) and water as precursors, a surface reaction occurs at 150-300°C. TMA decomposes to form an Al(CH3)2* intermediate, which then reacts with water to form an Al2O3 layer. The growth thickness per cycle is approximately 0.1nm, and can be precisely controlled to 2-50nm. Initially, amorphous Al2O3 forms. After annealing at 300-400°C, it transforms into γ-Al2O3, increasing its density from 2.8g / cm³ to 3.6g / cm³. Porosity is less than 1%, forming a continuous, pinhole-free protective film. The aluminum oxide layer formed on the coating's surface effectively blocks moisture and oxygen, significantly extending the coating's lifespan and stability. Aluminum oxide's low surface energy (approximately 40mJ / m²) provides chemical inertness and protects the coating, dissipating external stress. Interfacial chemical bonding (such as Al-O-Si bonds) forms a "gradient protection system" between the aluminum oxide layer and the underlying coating. The nanoscale Al₂O₃ layer fills the coating's surface roughness (Ra reduced from 0.1μm to <0.05μm), reducing light scattering and ultimately reducing scattering losses by 20% at 193nm. The aluminum oxide layer's high refractive index optically matches the coating, creating an optical synergy that reduces reflectivity at 193nm from 5% to <1%. Of course, the aluminum oxide layer should be limited in thickness. If it exceeds 50nm, the aluminum oxide layer itself will act as a reflector, inhibiting the coating's absorption of stray light.

[0035] According to some embodiments of the present disclosure, another embodiment of the present disclosure provides a method for preparing a photomask protective film frame, such as Figure 3 The photomask protective film frame includes a frame body made of metal material and a coating formed on the surface of the frame body. The preparation method includes using metal material to make the frame body; and depositing a coating composed of carbon black, silica particles and organic dyes on the frame body.

[0036] In some embodiments, the metal is one of aluminum, titanium, aluminum alloy, titanium alloy, and stainless steel; the organic dye is one of aniline black and copper phthalocyanine; the mass ratio of the organic dye, carbon black, and silica particles in the coating is: 5~20:10~40:70~90, the carbon black particle size is 5~50nm, and the silica particle size is 5~100nm.

[0037] In some embodiments, the coating has a thickness of 5 to 100 μm, and the coating further comprises a binder, which is one of PVDF, epoxy resin, silicone resin, polyimide, and KH550.

[0038] In some embodiments, an aluminum oxide layer is further provided on the coating, wherein the aluminum oxide layer has a thickness of 2 to 50 nm. The aluminum oxide layer is grown on the coating surface using an atomic layer deposition (ALD) or chemical vapor deposition (CVD) process, and its formation process involves precursor decomposition and densification.

[0039] In some embodiments, the coating is prepared using a sol-gel method, electrophoretic deposition, or screen printing. The surface of the frame body is pretreated before coating. This pretreatment may include: ultrasonic cleaning for 15 minutes using one or more of an acid solution, an alkaline solution, deionized water, or acetone to remove oil; sandblasting using 50-100 μm Al2O3 particles (at a pressure of 0.3-0.5 MPa) to create a rough surface with a Ra of 1-3 μm to improve coating adhesion.

[0040] In some embodiments, the coating is prepared using a sol-gel method. Specifically, the following steps include: mixing a silica precursor (e.g., tetraethyl orthosilicate) with ethanol and water. A hydrolysis-polycondensation reaction occurs under the action of an acidic or alkaline catalyst (e.g., hydrochloric acid or aqueous ammonia) to form a silica sol. A pre-dispersed carbon black particle system and an organic dye are then added to prevent carbon black agglomeration. The mixture is stirred to form a composite sol. The sol is then applied to the surface of the frame body by dip coating, spin coating, or spray coating. The frame body material is pre-treated with degreasing, cleaning, sandblasting, and other roughening treatments to improve surface adhesion. The coating then undergoes gelation and curing, drying at room temperature or low temperature (e.g., 60-100°C) to evaporate the solvent in the sol and form a gel coating with a three-dimensional network structure. Finally, the coating is cured by heat treatment (e.g., 150-300°C) to enhance coating density. By adjusting the sol concentration (e.g., silica content 10-30wt%) and the number of coatings (1-5), the coating thickness can be controlled within a range of 5-100μm. The thickness of a single dip coating is usually 1-5μm, and multiple coatings can reach the target thickness.

[0041] In the sol-gel method, a binder, such as 1wt% to 10wt% KH550 or PVDF, can be added to the silica sol after it is obtained. Stirring is continued until uniformly dispersed, followed by the addition of carbon black particles and an organic dye. Alternatively, carbon black particles and an organic dye can be added to the silica sol after it is obtained, stirred until uniformly dispersed, and then a binder, such as 1wt% to 10wt% KH550 or PVDF, can be added. Stirring is continued until uniformly dispersed to form a composite sol. The sol is applied to the frame surface by dip coating, spin coating, or spray coating. The frame material is pre-treated with degreasing, cleaning, sandblasting, and other treatments to improve surface adhesion. The gelation and curing process then proceeds. Drying is performed at room temperature or low temperature (e.g., 60-100°C) to evaporate the solvent in the sol, forming a gel coating with a three-dimensional network structure. Finally, heat treatment (e.g., 150-300°C) is performed to cure the coating and enhance its density. By adjusting the sol concentration (such as silica content, binder content) and the number of coatings, the thickness can be controlled within the range of 5-100μm.

[0042] In some embodiments, the coating is prepared using electrophoretic deposition. Specifically, carbon black, silica particles, and an organic dye are dispersed in a polar solvent (e.g., ethanol or acetone), and an appropriate amount of electrolyte (e.g., ammonium acetate) is added to adjust conductivity. Ultrasonic treatment (30-60 minutes) is then performed to ensure uniform particle dispersion and prevent agglomeration, resulting in a suspension. A conductive framework serves as one electrode, while an inert electrode serves as a counter electrode. A DC electric field (voltage 10-100V, duration 1-10 minutes) is applied to the suspension. Under the influence of the electric field, the charged particles migrate toward the electrodes and deposit, forming a coating. After deposition, the coating is dried (e.g., at 80°C for 2 hours) to remove the solvent. If necessary, low-temperature sintering (≤200°C) can be performed to enhance adhesion. In electrophoretic deposition, the electric field strength and deposition time directly influence the thickness: higher voltages and longer deposition times result in greater thickness (typically, 1-5 μm can be deposited per minute). By adjusting these parameters, the coating can be precisely controlled within the 5-100 μm range.

[0043] In some embodiments, the coating is prepared using a screen printing process as follows: Slurry preparation: Carbon black, silica particles, and an organic dye are mixed, and a binder (e.g., epoxy resin, acrylic resin) and a solvent (e.g., butanone, toluene) are added to form a slurry with an appropriate viscosity (fluidity can be adjusted by adding a thickener). Printing: A frame material, such as an aluminum alloy substrate, is secured to the substrate. The slurry is applied to the surface using a squeegee through a screen (50-200 mesh). The slurry is deposited through the mesh openings to form a patterned coating. Curing: After printing, the coating is cured at room temperature or heated (e.g., 120-180°C) to crosslink the binder and enhance coating adhesion. The thickness of the screen and the number of squeegee strokes during screen printing determine the coating thickness: a single print thickness is approximately 5-20 μm, while multiple squeegee strokes (2-3 times) can reach 100 μm.

[0044] According to some embodiments of the present disclosure, another aspect of the present disclosure further provides a photomask protective film, comprising a photomask protective film frame and a protective film adhered to an upper surface of the frame.

[0045] According to some embodiments of the present disclosure, another aspect of the present disclosure further provides a photomask, see Figure 4 The photomask includes: a transparent substrate 1; a mask pattern 2 located on the surface of the transparent substrate; a photomask protective film frame 4, one end of the photomask protective frame 4 is fixed to the transparent substrate 1 by an adhesive, and the other end is connected to a protective film 5 by an adhesive, the photomask protective film frame 4 completely surrounds the mask pattern area, and the photomask protective film frame 4 includes a frame body 6 made of metal material and a coating 7 formed on the surface of the frame body 6.

[0046] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a photomask, which includes: a transparent substrate 1; a mask pattern 2 located on the surface of the transparent substrate; a mask protective film frame 4, one end of the mask protective frame 4 is fixed to the transparent substrate 1 by an adhesive, and the other end is connected to a protective film 5 by an adhesive, the mask protective film frame 4 completely surrounds the mask pattern area, and the mask protective film frame 4 includes a frame body 6 made of metal material, a coating 7 formed on the surface of the frame body 6, and an aluminum oxide layer 8 located on the coating 7.

[0047] Next, the present invention will be described with reference to Examples and Comparative Examples. It should not be understood that the present invention is limited to or by the Examples.

[0048] Example 1: Prepare an aluminum alloy photomask protective film frame. The frame body is made of aluminum alloy. The aluminum alloy is pretreated as follows: 5% NaOH etching + sandblasting, with Ra of 2.5μm. The coating composition is as follows: carbon black with a particle size of 20nm, accounting for 10% by weight; silica particles with a particle size of 50nm, accounting for 75% by weight; and aniline black, accounting for 15% by weight. It is made using the sol-gel method (with epoxy resin added as a binder, which accounts for 5% of the total weight of carbon black, silica particles and aniline black).

[0049] A 20 nm thick aluminum oxide layer was deposited using ALD. The specific preparation is as follows: ① Preparation of silica sol: TEOS: ethanol = 1:4 or 1:3 (volume ratio), add 0.1M HCl catalyst, and stir at 60℃ for 2h; ② Preparation of composite sol: Add carbon black (ultrasonic dispersion for 30 min), aniline black, and epoxy resin in proportion and stir for 12 h; ③ Coating and curing: pulling speed 3cm / min, heat treatment at 150℃ for 2h, repeat 3 times until the thickness reaches 15μm; ④ Alumina layer deposition: TMA + water precursor, 200℃, 200 cycles.

[0050] The protective film frame was tested and found to have an absorptivity of 96.5% and a reflectivity of 1.2% at 193nm; a pencil hardness of 3H and an adhesion of 5B (cross-hatch method).

[0051] Example 2: A titanium alloy photomask protective film frame was prepared. The frame body was made of Ti-6Al-4V titanium alloy. The titanium alloy was pretreated as follows: 5% dilute hydrochloric acid rinse + acetone rinse + deionized water ultrasonic cleaning, sandblasting roughening, Ra was 2μm).

[0052] 1. Materials and parameters Coating composition: carbon black: particle size 20nm, mass proportion 20%; silica particles: particle size 50nm, mass proportion 70%; organic dye: copper phthalocyanine, mass proportion 10%.

[0053] Preparation method: electrophoretic deposition, without aluminum oxide layer.

[0054] 2. The preparation steps are as follows: ① Preparation of suspension: Carbon black + silica + copper phthalocyanine were dispersed in ethanol (solid content 15%), 0.5% ammonium acetate was added, and ultrasonication was performed for 60 min; ② Electrophoretic deposition: 30V DC voltage, deposition for 3 minutes, drying at 80℃ for 1 hour; ③ Thickness control: single deposition 8μm, total thickness 55μm.

[0055] The protective film frame was tested and found to have an absorptivity of 97.2% and a reflectivity of 0.8% at 633nm. The coating remained scratch-free after 1,000 friction cycles and had a bonding strength of 7N / cm. It also showed no decomposition or coating shedding after being baked at 300°C for 2 hours.

[0056] Example 3: Prepare a stainless steel photomask protective film frame. The frame body is made of stainless steel and pretreated as follows: 5% NaOH etching + acetone ultrasonic cleaning + sandblasting roughening, Ra is 1.5μm) The coating composition is as follows: carbon black with a particle size of 20nm, accounting for 12% by weight; silica particles with a particle size of 30nm, accounting for 70% by weight; and aniline black, accounting for 18% by weight. It is prepared using the sol-gel method (PVDF with a total weight of 10% of the total weight of carbon black, silica particles, and aniline black is added as a binder).

[0057] ALD was used to deposit 2nm and 50nm thick aluminum oxide layers, respectively. The specific preparation is as follows: ① Preparation of silica sol: TEOS: ethanol = 1:4 or 1:3 (volume ratio), add 0.1M HCl catalyst, and stir at 60℃ for 2h; ② Preparation of composite sol: Add carbon black (ultrasonic dispersion for 30 min), aniline black, and PVDF in proportion and stir for 12 h; ③ Coating and curing: pulling speed 3cm / min, heat treatment at 150℃ for 2h, repeat 3 times until the thickness reaches 100μm; ④ Alumina layer deposition: TMA + water precursor, 200°C, select the number of cycles according to the deposition thickness.

[0058] The protective film frame was tested and its reflectivity at 193nm was 1.4% and 0.8% respectively; the adhesion was both 5B level (cross-hatch method).

[0059] Comparative Example 1: A titanium alloy photomask protective film frame was prepared. The frame body was made of Ti-6Al-4V titanium alloy. The titanium alloy was pretreated as follows: 5% dilute hydrochloric acid rinse + acetone rinse + deionized water ultrasonic cleaning, sandblasting roughening, Ra was 2μm).

[0060] 1. Materials and parameters Coating composition: carbon black: particle size 20nm, mass proportion 7%; silica particles: particle size 50nm, mass proportion 70%; organic dye: copper phthalocyanine, mass proportion 23%.

[0061] Preparation method: electrophoretic deposition, without aluminum oxide layer.

[0062] 2. The preparation steps are as follows: ① Preparation of suspension: Carbon black + silica + copper phthalocyanine were dispersed in ethanol (solid content 15%), 0.5% ammonium acetate was added, and ultrasonication was performed for 60 min; ② Electrophoretic deposition: 30V DC voltage, deposition for 3 minutes, drying at 80℃ for 1 hour; ③ Thickness control: single deposition 8μm, total thickness 24μm.

[0063] The protective film frame was tested and found to have an absorptivity of 92.7% and a reflectivity of 3.4% at 633nm. The coating showed slight wear after 1,000 frictions but no obvious scratches. It showed no decomposition and no peeling of the coating after being baked at 300°C for 2 hours.

[0064] Comparative Example 2 Prepare a stainless steel photomask protective film frame. The frame body is made of stainless steel and pretreated as follows: 5% NaOH etching + acetone ultrasonic cleaning + sandblasting roughening, Ra is 1.5μm) The coating composition is as follows: carbon black with a particle size of 20nm, accounting for 12% by weight; silica particles with a particle size of 30nm, accounting for 70% by weight; and aniline black, accounting for 18% by weight. It is prepared using the sol-gel method (PVDF with a total weight of 10% of the total weight of carbon black, silica particles, and aniline black is added as a binder).

[0065] A 60nm thick aluminum oxide layer was deposited using ALD. The specific preparation is as follows: ① Preparation of silica sol: TEOS: ethanol = 1:4 or 1:3 (volume ratio), add 0.1M HCl catalyst, and stir at 60℃ for 2h; ② Preparation of composite sol: Add carbon black (ultrasonic dispersion for 30 min), aniline black, and PVDF in proportion and stir for 12 h; ③ Coating and curing: pulling speed 3cm / min, heat treatment at 150℃ for 2h, repeat until the thickness reaches 15μm; ④ Alumina layer deposition: TMA + water precursor, 200°C, select the number of cycles according to the deposition thickness.

[0066] The protective film frame was tested and its reflectivity at 193nm was 4.5%; its adhesion was level 3B (cross-hatch method), and sporadic cracking occurred under long-term light exposure.

[0067] Comparative Example 3 Prepare a stainless steel photomask protective film frame. The frame body is made of stainless steel and pretreated as follows: 5% NaOH etching + acetone ultrasonic cleaning + sandblasting roughening, Ra is 1.5μm) The coating composition is as follows: carbon black with a particle size of 20nm, accounting for 40% by weight; silica particles with a particle size of 120nm, accounting for 20% by weight; and aniline black, accounting for 40% by weight. It is prepared using the sol-gel method (PVDF with a total weight of 15% of the total weight of carbon black, silica particles, and aniline black is added as a binder).

[0068] A 35nm thick aluminum oxide layer was deposited using ALD. The specific preparation is as follows: ① Preparation of silica sol: TEOS: ethanol = 1:3 (volume ratio), add 0.1M HCl catalyst, stir at 60℃ for 2h; ② Preparation of composite sol: Add carbon black (ultrasonic dispersion for 30 min), aniline black, and PVDF in proportion and stir for 12 h; ③ Coating and curing: pulling speed 3cm / min, heat treatment at 150℃ for 2h, repeat until the thickness reaches 65μm; ④ Alumina layer deposition: TMA + water precursor, 200°C, select the number of cycles according to the deposition thickness.

[0069] The protective film frame was tested and its reflectivity at 193nm was 7.5%. Scratches appeared after 50 frictions, and the coating partially cracked and bulged after 50 cycles of the mask.

[0070] The protective film frame and protective film obtained by the technical solution provided by the embodiments of this disclosure have an optical absorption rate of over 95% within a wide wavelength range of 193nm-700nm. They retain their properties and exhibit excellent mechanical properties with no cracks, even after long-term use. The addition of an aluminum oxide layer to the coating also significantly improves optical absorption, wear resistance, and weather resistance.

[0071] The photomask in this application is suitable for photolithography processes in semiconductor manufacturing, flat-panel displays, microelectromechanical systems (MEMS), and other fields. It can meet the needs of high-end photolithography processes and provide key support for the manufacture of advanced integrated circuits. With the continuous development of semiconductor and micro-nano manufacturing technologies, the demand for high-performance photomasks will continue to grow. This technical solution has broad application prospects and market potential.

[0072] The above detailed description of a photomask pellicle frame and its preparation method further illustrates the present invention in conjunction with specific preferred embodiments. The present invention should not be construed as being limited to these descriptions. Those skilled in the art will appreciate the flexibility and adaptability of the design, allowing for the development of a series of products, without departing from the present invention. Simple deductions or substitutions should be considered within the scope of the patent protection of the present invention as defined by the submitted claims.

[0073] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

Claims

1. A photomask protective film frame, comprising a frame body made of a metal material and a coating formed on the surface of the frame body, characterized in that: The coating consists of at least carbon black, silicon dioxide particles and organic dye.

2. The pellicle frame according to claim 1, wherein: The metal is one of aluminum, titanium, aluminum alloy, titanium alloy and stainless steel.

3. The pellicle frame according to claim 1, wherein: The organic dye is one of aniline black and copper phthalocyanine.

4. The pellicle frame according to claim 1, wherein: The coating thickness is 5-100 μm.

5. The pellicle frame according to claim 1, wherein: The mass ratio of the organic dye, carbon black and silicon dioxide particles in the coating is 5-20:10-40:70-90, the carbon black particle size is 5-50 nm, and the silicon dioxide particle size is 5-100 nm.

6. The pellicle frame according to claim 1, wherein: The coating further includes a binder, which is one of PVDF, epoxy resin, silicone resin, polyimide, and KH550.

7. The pellicle frame according to claim 1, wherein: An aluminum oxide layer is also provided on the coating layer, and the thickness of the aluminum oxide layer is 2-50 nm.

8. A method for preparing a photomask protective film frame, wherein the photomask protective film frame includes a frame body made of a metal material and a coating formed on the surface of the frame body. The preparation method includes using the metal material to make the frame body; and depositing a coating composed of carbon black, silica particles and organic dyes on the frame body.

9. The method for preparing a photomask protective film frame according to claim 8, wherein: The metal is one of aluminum, titanium, aluminum alloy, titanium alloy, and stainless steel; the organic dye is one of aniline black and copper phthalocyanine; the mass ratio of the organic dye, carbon black, and silica particles in the coating is: 5~20:10~40:70~90; the carbon black particle size is 5~50nm, and the silica particle size is 5~100nm.

10. The method for preparing a photomask protective film frame according to claim 8, wherein: The coating has a thickness of 5 to 100 μm. The coating further comprises a binder, which is one of PVDF, epoxy resin, silicone resin, polyimide, and KH550.

11. The method for preparing a photomask protective film frame according to claim 8, wherein: An aluminum oxide layer is also provided on the coating layer, and the thickness of the aluminum oxide layer is 2-50 nm.

12. The method for preparing a photomask protective film frame according to claim 8, wherein: The coating is prepared by a sol-gel method, an electrophoretic deposition method or a screen printing method. 13 . A photomask protective film, comprising the photomask protective film frame according to claim 1 and a protective film adhered to an upper surface of the frame.

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