Invar alloy mask plate plasma nanometer polishing thinning system and thinning method

Abstract

The invention relates to an invar alloy mask plate plasma nanometer polishing and thinning system and method, the system comprises a water tank (2), the water tank (2) is filled with a polishing solution (3) and an invar alloy mask plate (4), and the depth of the invar alloy mask plate (4) in the water tank (2) is controlled through a lifting system controller (5) and a lifting device (6); the polishing solution (3) comprises main salt, auxiliary salt and water; the main salt comprises (conductive electrolyte for generating plasma) 1-2% of potassium citrate and 1-2% of potassium nitrate; the auxiliary salt comprises a buffering agent, a thickening agent, a protective agent and a brightening agent. Through the synergistic effect of a special polishing solution formula and an optimization process, efficient and uniform thinning and nanoscale polishing of the ultrathin invar alloy mask plate are achieved, the surface flatness and environmental protection property are improved while the natural color gloss of metal is guaranteed and edge burning and salt residue are avoided, and the high-precision use requirement of the mask plate is met.

Description

Technical Field

[0001] This invention relates to the field of metal film plate thinning technology, and more specifically, to an Invar alloy mask plate plasma nanopolishing thinning system and thinning method. Background Technology

[0002] Plasma liquid nanopolishing (PLNP) technology is based on the principle of vapor-liquid plasma generation. It forms a uniform plasma layer on the workpiece surface using a polishing slurry. Utilizing the preferential dissolution of protrusions on the anolyte metal surface, surface roughness reaches or approaches the nanometer level. This technology offers advantages such as conformal machining, controllable precision, and no alteration of the material matrix properties. Invar alloys, with their extremely low coefficient of thermal expansion, excellent dimensional stability, and mechanical strength, are the core substrate for photomasks in precision manufacturing fields such as semiconductor chips and display panels. The thickness of Invar alloy substrates used in photomasks is typically 10μm to 60μm, requiring stringent requirements simultaneously for high surface finish, no damage, no edge deformation, and uniform thickness reduction. Current polishing methods for Invar alloys mostly employ traditional chemical polishing or general-purpose plasma liquid nanopolishing. For example, polishing slurries containing mixed salts such as sulfates and phosphates primarily use electrolytes to conduct current and excite plasma, supplemented by organic acids to regulate the overall reaction. However, such technical solutions are not designed to be compatible with the ultra-thin characteristics of Invar alloys used in photomasks, as well as the thinning and polishing processes, resulting in defects such as edge burning, uneven thickness, and salt residue. They are therefore unable to meet the requirements of industrial-scale photomask production.

[0003] The existing technology has the following drawbacks:

[0004] (1) Insufficient uniformity of thinning: For ultra-thin sheets of 10μm to 60μm, the reaction intensity of existing polishing liquid is difficult to control precisely, which can easily lead to excessive edge corrosion (burning) or uneven thickness, resulting in scrapping of the substrate;

[0005] (2) Surface quality is not up to standard: The surface gloss is poor after polishing and salt crystal residue is easy to be generated, which cannot meet the strict requirements of the mask for the metal's natural gloss and cleanliness, and affects the accuracy of pattern transfer;

[0006] (3) Low process efficiency: The processing time for a single batch is relatively long, which makes it difficult to meet the needs of large-scale production of photomasks;

[0007] (4) Poor environmental performance: Some polishing systems contain components that are difficult to degrade, resulting in high environmental treatment costs and failing to meet the requirements of green production. Summary of the Invention

[0008] To address the aforementioned technical deficiencies in existing technologies, the present invention aims to provide an Invar alloy mask plate plasma nanopolishing thinning system and method. Through the synergistic effect of a specialized polishing fluid formula and optimized process, the system achieves efficient and uniform thinning and nanoscale polishing of ultra-thin Invar alloy mask plates. While ensuring the natural luster of the metal and avoiding burnt edges and salt residue, the system also improves surface flatness and environmental friendliness, meeting the high-precision requirements of mask plates.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following solution:

[0010] The first aspect of this invention provides a plasma nanopolishing and thinning system for an Invar alloy mask. The system includes a water tank containing a polishing fluid and an Invar alloy mask. The depth of the Invar alloy mask within the water tank is controlled by a lifting system controller and a lifting device. The polishing fluid formulation is as follows: potassium citrate: 1%–2%; potassium nitrate: 1%–2%; sodium bicarbonate: 0.5%–1%; sodium carboxymethyl cellulose: 0.2%–0.5%; trisodium phosphate: 0.2%–0.5%; sodium silicate: 0.2%–0.5%; sodium gluconate: 0.2%–0.5%. 0.5%–1%; all components are expressed as a percentage of water by mass, and the water is deionized water; potassium citrate and potassium nitrate are the main polishing salts (serving as conductive electrolytes to generate plasma); sodium bicarbonate is a buffer (serving as a pH stabilizer); sodium carboxymethyl cellulose is a thickener (serving as a stabilizer for the polishing gas layer); trisodium phosphate and sodium silicate are protective agents (serving as a form of oxide film to prevent over-polishing and electro-corrosion); sodium gluconate is a brightener (serving as a way to enhance the natural luster of the metal).

[0011] Preferably, the polishing liquid includes polishing liquid F1, polishing liquid F2, polishing liquid F3, polishing liquid F4, and polishing liquid F5.

[0012] In any of the above schemes, it is preferred that the polishing liquid F1 is formulated as follows: by mass percentage of water, potassium citrate: 1%, potassium nitrate: 1%, sodium bicarbonate: 0.5%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, and mixed with the remaining water, and stirred until completely dissolved.

[0013] In any of the above embodiments, it is preferred that the polishing liquid F2 is formulated as follows: by mass percentage of water, potassium citrate: 2%, potassium nitrate: 2%, sodium bicarbonate: 0.5%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, and the remaining water are mixed and stirred until completely dissolved.

[0014] In any of the above embodiments, it is preferred that the polishing liquid F3 is formulated as follows: by mass percentage of water, potassium citrate: 2%, potassium nitrate: 2%, sodium bicarbonate: 1%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, and the remaining water are mixed and stirred until completely dissolved.

[0015] In any of the above embodiments, it is preferred that the polishing liquid F4 is formulated as follows: by mass percentage of water, take 2% potassium citrate, 2% potassium nitrate, 1% sodium bicarbonate, 0.5% sodium carboxymethyl cellulose, 0.2% trisodium phosphate, 0.2% sodium silicate, and 0.5% sodium gluconate, mix with the remaining water, and stir until completely dissolved.

[0016] In any of the above embodiments, it is preferred that the polishing liquid F5 is formulated as follows: by mass percentage of water, take 2% potassium citrate, 2% potassium nitrate, 1% sodium bicarbonate, 0.5% sodium carboxymethyl cellulose, 0.5% trisodium phosphate, 0.2% sodium silicate, and 0.5% sodium gluconate, mix with the remaining water, and stir until completely dissolved.

[0017] A second aspect of the present invention provides a method for thinning an Invar alloy mask plate using plasma nanopolishing, wherein the polishing method comprises the following steps in sequence:

[0018] Step 1, Prepare the polishing solution: Mix the main salt, auxiliary salt and water in proportion, and stir until completely dissolved to obtain a uniform and transparent polishing solution;

[0019] Step 2, place the Invar alloy mask plate for thinning: heat the polishing slurry to 75℃~85℃; turn on the power, use constant pressure mode, and slowly immerse the Invar alloy mask plate into the polishing slurry at a fixed speed through the lifting system, and control the polishing time to 40s~60s.

[0020] Step 3, water washing: Remove the thinned Invar alloy mask from the liquid surface and rinse it with deionized water 2-3 times to thoroughly remove surface residue;

[0021] Step 4, Drying: Place the washed Invar alloy mask plate into an oven at 60℃~80℃ and dry for 5min~10min;

[0022] Step 5, Thickness and Surface Quality Inspection: Inspect the thickness uniformity and surface quality of the finished product to ensure it is qualified. If it is not qualified, return to step 2 for further processing; if it is qualified, it becomes the finished mask.

[0023] Preferably, the polishing method employs plasma liquid nanopolishing technology, which greatly improves production efficiency and ultimately achieves an environmentally friendly, energy-saving, efficient, and stable polishing effect production mode.

[0024] In summary, the Invar alloy photomask plasma nanopolishing and thinning system of the present invention has the following advantages: Enhanced adaptability: Designed for the thinning and polishing needs of ultra-thin photomasks ranging from 10μm to 60μm, effectively avoiding edge burning and uneven thickness, and ensuring the structural integrity of the substrate; Excellent surface quality and thickness control: After polishing, the photomask retains its metallic luster, high flatness, no salt residue, and thickness uniformity that meets the requirements of photolithography; High process efficiency: Integrating thinning and polishing optimizes the process flow and improves production efficiency; Outstanding environmental friendliness: All components used are environmentally friendly salts, easy to handle, and meet green manufacturing requirements. Attached Figure Description

[0025] Figure 1 This is a structural block diagram of the Invar alloy mask plasma nanopolishing and thinning system according to the present invention.

[0026] Figure 2 This is a process flow diagram of the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention.

[0027] Figure 3 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the gloss of the mask and time after treatment with polishing fluid F1.

[0028] Figure 4 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the thickness of the mask plate and time after treatment with polishing fluid F1.

[0029] Figure 5 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the gloss of the mask and time after treatment with polishing fluid F2.

[0030] Figure 6 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the thickness of the mask plate and time after treatment with polishing fluid F2.

[0031] Figure 7 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the gloss of the mask and time after treatment with polishing fluid F3.

[0032] Figure 8 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2The figure shown in the embodiment is a curve showing the relationship between the thickness of the mask plate and time after treatment with polishing fluid F3.

[0033] Figure 9 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the gloss of the mask and time after treatment with polishing fluid F4.

[0034] Figure 10 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the thickness of the mask plate and time after treatment with polishing fluid F4.

[0035] Figure 11 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the gloss of the mask and time after treatment with polishing fluid F5.

[0036] Figure 12 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the thickness of the mask plate and time after treatment with polishing fluid F5.

[0037] Figure 13 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the gloss of the mask and time after treatment with polishing fluid C3.

[0038] Figure 14 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment illustrates the relationship between the thickness of the mask plate and time after treatment with polishing fluid C3.

[0039] Figure 15 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the gloss of the mask and time after treatment with polishing fluid C4.

[0040] Figure 16 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment illustrates the relationship between the thickness of the mask plate and time after treatment with polishing fluid C4.

[0041] Figure 17 The graph shows the relationship between the gloss of the mask plate and time under the treatment with polishing fluid C5 according to the plasma nanopolishing thinning method of Invar alloy mask plate according to the present invention.

[0042] Figure 18 The Invar alloy mask plate plasma nanopolishing thinning method according to the present invention Figure 2 The figure shown in the embodiment is a curve showing the relationship between the thickness of the mask plate and time after treatment with polishing fluid C5.

[0043] Explanation of icon numbers

[0044] 1. Power supply; 2. Water tank; 3. Polishing liquid; 4. Invar alloy mask plate; 5. Lifting system controller; 6. Lifting device. Detailed Implementation

[0045] The following description is merely exemplary and not intended to limit this disclosure, its application, or its uses. The specific embodiments of the Invar alloy mask plasma nanopolishing thinning system and method of the present invention will be further described below with reference to the accompanying drawings.

[0046] like Figure 1 The diagram shows a preferred embodiment of the Invar alloy mask plasma nanopolishing and thinning system according to the present invention. A first aspect of the present invention provides an Invar alloy mask plasma nanopolishing and thinning system, comprising a water tank 2 containing a polishing fluid 3 and an Invar alloy mask 4. The depth of the Invar alloy mask 4 within the water tank 2 is controlled by a lifting system controller 5 and a lifting device 6. The polishing fluid 3 has the following formulation: potassium citrate: 1%–2%; potassium nitrate: 1%–2%; sodium bicarbonate: 0.5%–1%; sodium carboxymethyl cellulose: 0.2%–0.5%; trisodium phosphate: 0.2%–0.5%; sodium silicate: 0.2%–0.5%; sodium gluconate: 0.5%–1%; all components are expressed as a percentage of water by mass, and the water is deionized water; potassium citrate and potassium nitrate are the main polishing salts (serving as conductive electrolytes to generate plasma); sodium bicarbonate is a buffer (serving as a pH stabilizer); sodium carboxymethyl cellulose is a thickener (serving as a stabilizer for the polishing gas layer); trisodium phosphate and sodium silicate are protective agents (serving as a form of oxide film to prevent over-polishing and electro-corrosion); sodium gluconate is a brightener (serving as a way to enhance the natural luster of the metal).

[0047] See Figure 2 As shown, a second aspect of the present invention provides a method for thinning an Invar alloy mask plate using plasma nanopolishing, wherein the polishing method sequentially performs the following steps:

[0048] Step 1, Prepare the polishing solution: Mix the main salt, auxiliary salt and water in proportion, and stir until completely dissolved to obtain a uniform and transparent polishing solution;

[0049] Step 2, place the Invar alloy mask plate for thinning: heat the polishing slurry to 80°C; turn on the power, use constant pressure mode, and slowly immerse the Invar alloy mask plate into the polishing slurry at a fixed speed through the lifting system, controlling the polishing time to 40s to 60s.

[0050] Step 3, water washing: Remove the thinned Invar alloy mask from the liquid surface and rinse it with deionized water 2-3 times to thoroughly remove surface residue;

[0051] Step 4, Drying: Place the washed Invar alloy mask plate into an oven at 60℃~80℃ and dry for 5min~10min;

[0052] Step 5, Thickness and Surface Quality Inspection: Inspect the thickness uniformity and surface quality of the finished product to ensure it is qualified. If it is not qualified, return to step 2 for further processing; if it is qualified, it becomes the finished mask.

[0053] The polishing liquids described in this invention include polishing liquid F1, polishing liquid F2, polishing liquid F3, polishing liquid F4, polishing liquid F5, and polishing liquids C1-C5.

[0054] See next. Figure 3 , Figure 4 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss, thickness and time of the mask plate treated with polishing fluid F1.

[0055] In this embodiment, the polishing solution F1 is formulated as follows: by mass percentage of water, potassium citrate: 1%, potassium nitrate: 1%, sodium bicarbonate: 0.5%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, and the remaining water are mixed and stirred until completely dissolved. The mask is connected to the positive terminal of the power supply, and the stainless steel processing tank is connected to the negative terminal. A constant voltage processing mode is adopted, with the processing voltage set to 280V, the processing temperature to 80℃, and the polishing time to 60s. The gloss and thickness of the mask surface are detected every 10s. The experimental results are as follows. Figure 2 As shown, the surface gloss of the photomask increases steadily with increasing processing time, while the thickness decreases steadily, ultimately meeting the preset process requirements.

[0056] like Figure 5 , 6 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss and thickness of the mask plate and time after treatment with polishing fluid F2.

[0057] In this embodiment, the polishing fluid F2 is formulated as follows: by mass percentage of water, potassium citrate: 2%, potassium nitrate: 2%, sodium bicarbonate: 0.5%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, and the remaining water are mixed and stirred until completely dissolved. The mask is connected to the positive terminal of the power supply, and the stainless steel processing tank is connected to the negative terminal. A constant voltage processing mode is adopted, with the processing voltage set to 280V, the processing temperature to 80℃, and the polishing time to 60s. The gloss and thickness of the mask surface are detected every 10s. The experimental results are as follows. Figure 3 As shown, the surface gloss of the photomask increases steadily with increasing processing time, while the thickness decreases steadily, ultimately meeting the preset process requirements.

[0058] like Figure 7 , 8 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss and thickness of the mask plate and time after treatment with polishing fluid F3.

[0059] In this embodiment, the polishing fluid F3 is formulated as follows: by mass percentage of water, potassium citrate: 2%, potassium nitrate: 2%, sodium bicarbonate: 1%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, and the remaining water are mixed and stirred until completely dissolved. The mask is connected to the positive terminal of the power supply, and the stainless steel processing tank is connected to the negative terminal. A constant voltage processing mode is adopted, with the processing voltage set to 280V, the processing temperature to 80℃, and the polishing time to 60s. The gloss and thickness of the mask surface are measured every 10s. The experimental results are as follows. Figure 4 As shown, the surface gloss of the photomask increases steadily with increasing processing time, while the thickness decreases steadily, ultimately meeting the preset process requirements.

[0060] like Figure 9 , 10 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss, thickness and time of the mask plate after treatment with polishing fluid F4.

[0061] In this embodiment, the polishing fluid F4 is formulated as follows: by mass percentage of water, 2% potassium citrate, 2% potassium nitrate, 1% sodium bicarbonate, 0.5% sodium carboxymethyl cellulose, 0.2% trisodium phosphate, 0.2% sodium silicate, and 0.5% sodium gluconate are mixed with the remaining water and stirred until completely dissolved. The mask is connected to the positive terminal of the power supply, and the stainless steel processing tank is connected to the negative terminal. A constant voltage processing mode is adopted, with the processing voltage set to 280V, the processing temperature to 80℃, and the polishing time to 60s. The gloss and thickness of the mask surface are measured every 10s. The experimental results are as follows. Figure 5 As shown, the surface gloss of the photomask increases steadily with increasing processing time, while the thickness decreases steadily, ultimately meeting the preset process requirements.

[0062] like Figure 11 , 12 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss and thickness of the mask plate and time after treatment with polishing fluid F5.

[0063] In this embodiment, the polishing fluid F5 is formulated as follows: by mass percentage of water, 2% potassium citrate, 2% potassium nitrate, 1% sodium bicarbonate, 0.5% sodium carboxymethyl cellulose, 0.5% trisodium phosphate, 0.2% sodium silicate, and 0.5% sodium gluconate are mixed with the remaining water and stirred until completely dissolved. The mask is connected to the positive terminal of the power supply, and the stainless steel processing tank is connected to the negative terminal. A constant voltage processing mode is adopted, with the processing voltage set to 280V, the processing temperature to 80℃, and the polishing time to 60s. The gloss and thickness of the mask surface are measured every 10s. The experimental results are as follows. Figure 6 As shown, the surface gloss of the photomask increases steadily with increasing processing time, while the thickness decreases steadily, ultimately meeting the preset process requirements.

[0064] This invention also discloses a polishing slurry C1, which differs from polishing slurries F1-F5 in that potassium citrate is not added to the plasma nanopolishing slurry, resulting in Invar alloy plasma nanopolishing slurry C1 for mask plates. Experimental results show that the edges of the Invar alloy mask plate are rapidly burned black, and the overall surface gloss decreases.

[0065] The present invention also discloses a polishing slurry C2, which differs from polishing slurries F1-F5 in that: potassium nitrate is not added to the plasma nanopolishing slurry, and plasma nanopolishing slurry C2 is used to prepare Invar alloy mask plate. The experimental results show that the mask plate is reddish-brown overall, the surface roughness increases, and the brightness decreases.

[0066] like Figure 13 , 14 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss and thickness of the mask plate and time after treatment with polishing fluid C3.

[0067] The polishing slurry C3 in this invention differs from polishing slurries F1-F5 in that sodium bicarbonate is not added to the plasma nano-polishing slurry. Experimental results show that in the initial polishing period of 0-20s, the gloss of the Invar alloy mask increases and the thickness decreases. After polishing time exceeds 20s, the gloss of the mask surface gradually decreases and the thickness increases, and a black oxide film forms on the surface, thus deteriorating its polishing performance.

[0068] like Figure 15 , 16 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss, thickness and time of the mask plate treated with polishing fluid C4.

[0069] The polishing slurry C4 in this invention differs from polishing slurries F1-F5 in that: sodium carboxymethyl cellulose is not added to the plasma nano-polishing slurry. Experimental results show that: within the first 20 seconds of polishing, the gloss of the Invar alloy mask hardly changes, and the thickness decreases slightly; as the polishing time continues to increase, a gray matte oxide film appears on the surface of the mask, resulting in a decrease in its smoothness and an increase in its thickness.

[0070] See last for reference. Figure 17 , 18 As shown, the plasma nanopolishing thinning method for Invar alloy mask plates according to the present invention... Figure 2 The figure shown in the embodiment is a curve depicting the relationship between the gloss and thickness of the mask plate and time after treatment with polishing fluid C5.

[0071] The polishing slurry C5 in this invention differs from polishing slurries F1-F5 in that sodium gluconate is not added to the plasma nanopolishing slurry. Experimental results show that as polishing time increases, the smoothness of the Invar alloy mask increases and the thickness decreases, but the rate of change is significantly lower than the effect in the examples.

[0072] In this embodiment, the polishing method employs plasma liquid nanopolishing technology, which greatly improves production efficiency and ultimately achieves an environmentally friendly, energy-saving, efficient, and stable polishing effect production mode.

[0073] Those skilled in the art will readily understand that the Invar alloy mask plasma nanopolishing and thinning system of the present invention comprises any combination of the parts described in this specification. Due to space limitations and for the sake of brevity, these combinations are not described in detail here; however, after reading this specification, the scope of the invention, constituted by any combination of the parts described herein, is self-evident.

Claims

1. A plasma nanopolishing and thinning system for an Invar alloy mask, the system comprising a water tank (2), the water tank (2) containing a polishing fluid (3) and an Invar alloy mask (4), characterized in that: The depth of the Invar alloy mask plate (4) in the water tank (2) is controlled by the lifting system controller (5) and the lifting device (6); the polishing liquid (3) is formulated as follows: potassium citrate: 1% to 2%; Potassium nitrate: 1%–2%, sodium bicarbonate: 0.5%–1%, sodium carboxymethyl cellulose: 0.2%–0.5%, trisodium phosphate: 0.2%–0.5%, sodium silicate: 0.2%–0.5%, sodium gluconate: 0.5%–1%; all components are expressed as a percentage of water by mass, and the water is deionized water; potassium citrate and potassium nitrate are the main polishing salts; sodium bicarbonate is a buffer; sodium carboxymethyl cellulose is a thickener; trisodium phosphate and sodium silicate are protective agents; sodium gluconate is a brightener.

2. The Invar alloy mask plasma nanopolishing and thinning system as described in claim 1, characterized in that: The polishing fluid includes polishing fluid F1, polishing fluid F2, polishing fluid F3, polishing fluid F4, and polishing fluid F5.

3. The Invar alloy mask plate plasma nanopolishing and thinning system as described in claim 2, characterized in that: The polishing liquid F1 is formulated as follows: by mass percentage of water, take potassium citrate: 1%, potassium nitrate: 1%, sodium bicarbonate: 0.5%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, mix with the remaining water, and stir until completely dissolved.

4. The Invar alloy mask plate plasma nanopolishing and thinning system as described in claim 2, characterized in that: The polishing liquid F2 is formulated as follows: by mass percentage of water, take potassium citrate: 2%, potassium nitrate: 2%, sodium bicarbonate: 0.5%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, mix with the remaining water, and stir until completely dissolved.

5. The Invar alloy mask plasma nanopolishing and thinning system as described in claim 2, characterized in that: The polishing liquid F3 is formulated as follows: by mass percentage of water, take potassium citrate: 2%, potassium nitrate: 2%, sodium bicarbonate: 1%, sodium carboxymethyl cellulose: 0.2%, trisodium phosphate: 0.2%, sodium silicate: 0.2%, sodium gluconate: 0.5%, mix with the remaining water, and stir until completely dissolved.

6. The Invar alloy mask plasma nanopolishing and thinning system as described in claim 2, characterized in that: The polishing fluid F4 is formulated as follows: by mass percentage of water, take 2% potassium citrate, 2% potassium nitrate, 1% sodium bicarbonate, 0.5% sodium carboxymethyl cellulose, 0.2% trisodium phosphate, 0.2% sodium silicate, and 0.5% sodium gluconate, mix with the remaining water, and stir until completely dissolved.

7. The Invar alloy mask plasma nanopolishing and thinning system as described in claim 2, characterized in that: The polishing liquid F5 is formulated as follows: by mass percentage of water, take 2% potassium citrate, 2% potassium nitrate, 1% sodium bicarbonate, 0.5% sodium carboxymethyl cellulose, 0.5% trisodium phosphate, 0.2% sodium silicate, and 0.5% sodium gluconate, mix with the remaining water, and stir until completely dissolved.

8. A method for thinning an Invar alloy mask plate using plasma nanopolishing, characterized in that: The polishing method involves the following steps in sequence: Step 1, Prepare the polishing solution: Mix the main salt, auxiliary salt and water in proportion, and stir until completely dissolved to obtain a uniform and transparent polishing solution; Step 2, place the Invar alloy mask plate for thinning: heat the polishing slurry to 75℃~85℃; turn on the power, use constant pressure mode, and slowly immerse the Invar alloy mask plate into the polishing slurry at a fixed speed through the lifting system, and control the polishing time to 40s~60s. Step 3, water washing: Remove the thinned Invar alloy mask from the liquid surface and rinse it with deionized water 2-3 times to thoroughly remove surface residue; Step 4, Drying: Place the washed Invar alloy mask plate into an oven at 60℃~80℃ and dry for 5min~10min; Step 5, Thickness and Surface Quality Inspection: Inspect the thickness uniformity and surface quality of the finished product to ensure it is qualified. If it is not qualified, return to step 2 for further processing; if it is qualified, it becomes the finished mask.

9. The plasma nanopolishing and thinning method for Invar alloy mask plates as described in claim 8, characterized in that, This polishing method employs plasma liquid nanopolishing technology.

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