Method for cleaning ceramic pieces

Abstract

This invention provides a method for cleaning ceramic parts, comprising: a first cleaning process, in which a chemical solution is used to dissolve powdery particles generated during the molding process of the ceramic part; a second cleaning process, S21, rinsing the ceramic part with a specified acidic solution; S22, immersing the ceramic part after rinsing with the specified acidic solution in the specified acidic solution; S23, rinsing the immersed ceramic part with pure water; S24, wiping the ceramic part after rinsing with pure water with a polishing tool made of nanomaterials; S25, immersing the wiped ceramic part in deionized water and performing ultrasonic cleaning; S26, rinsing the ultrasonically cleaned ceramic part with pure water; and a third cleaning process, in which ultrasonic cleaning is used to clean the ceramic part to remove residual particles and solution. This invention can effectively remove suspended particles and damaged layers from ceramic parts, thereby solving the problem of excessive ceramic particle count and improving chip yield.

Description

[0001] This application is a Chinese patent application filed on May 20, 2021, entitled "Method for Cleaning Ceramic Parts". Divisional application of CN202110553437.8. Technical Field

[0002] This invention relates to the field of semiconductor manufacturing, and more specifically, to a method for cleaning ceramic parts. Background Technology

[0003] Integrated circuits, as the foundation and core of the information industry, are a strategic industry vital to the overall development of the national economy and society. Because the trenches and linewidths in integrated circuits are very small, even tiny particles can cause significant damage to the wafer (such as silicon wafer) manufacturing process. Particle contamination has severely hampered the advancement of the integrated circuit field to lower technology nodes. Particle control capability is also a crucial indicator for measuring equipment and process stability in integrated circuit manufacturing processes. Especially in advanced processes, the requirements for particle control are becoming increasingly stringent, posing greater challenges to integrated circuit equipment.

[0004] Alumina ceramics are ceramic materials primarily composed of alumina (Al₂O₃). As the most stable of oxides, they possess advantages such as high temperature resistance, corrosion resistance, wear resistance, high mechanical strength, high hardness, high electrical insulation, and low dielectric loss. These advantages have led to their increasing use in semiconductor devices. However, during the granulation, sintering, and machining processes, powdery particles inevitably form on the surface of this material. If these particles fall onto the wafer during semiconductor fabrication, they can affect the process results, such as disrupting the continuity of different wires, breaking connections within the same wire, or creating holes that lead to increased energy consumption and heat generation. If these particles are not removed, they will severely impact the process results and chip yield.

[0005] To remove particles from ceramic parts, they need to be cleaned. However, existing ceramic cleaning methods are insufficient to clean them thoroughly, leaving damaged layers and suspended particles that cannot meet the required particle count. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a ceramic part cleaning method that can effectively remove suspended particles and damaged layers on ceramic parts, thereby solving the problem of excessive ceramic particle quantity and improving chip yield.

[0007] To achieve the objective of this invention, a method for cleaning ceramic parts is provided, comprising: The first cleaning process uses a chemical solution to dissolve the powdery particles generated during the molding process of the ceramic parts; The second cleaning process involves using a specified acidic solution to soften and corrode particles on the ceramic part and remove the damaged layer. This softening and corrosion process includes: S21, rinsing the ceramic part with the specified acidic solution; S22, immersing the rinsed ceramic part in the specified acidic solution; S23, rinsing the immersed ceramic part with pure water; S24, wiping the rinsed ceramic part with a polishing tool made of nanomaterials; S25, immersing the wiped ceramic part in deionized water and performing ultrasonic cleaning; and S26, rinsing the ultrasonically cleaned ceramic part with pure water. The third cleaning process involves using ultrasonic cleaning to clean the ceramic parts in order to remove residual particles and solution from them.

[0008] The present invention has the following beneficial effects: The ceramic component cleaning method provided in this invention comprises three cleaning processes. The first cleaning process uses a chemical solution to dissolve particles on the ceramic component, effectively cleaning particles in large blind holes, wrinkles, and non-welding seams on the ceramic component surface. The second cleaning process uses a specified acidic solution to soften and corrode particles on the ceramic component and eliminate the damaged layer. Since the presence of this damaged layer is a significant source of particle generation, this method effectively removes particles at the source compared to existing technologies, thus greatly reducing the number of particles. The third cleaning process uses ultrasonic cleaning to remove residual particles and solution (acidic or alkaline solution) from the ceramic component, enabling comprehensive cleaning. Ultimately, this method effectively improves the cleaning effect, solves the problem of excessive ceramic particle count, and increases chip yield. Attached Figure Description

[0009] Figure 1 A flowchart illustrating a ceramic parts cleaning method provided in an embodiment of the present invention; Figure 2 This is a flowchart of the second cleaning process used in an embodiment of the present invention; Figure 3 This is a flowchart of the first cleaning process used in an embodiment of the present invention; Figure 4 This is a flowchart of the third cleaning process used in an embodiment of the present invention; Figure 5 Comparison images of the damaged layers on ceramic parts obtained by the existing ceramic part cleaning method and the ceramic part cleaning method provided in the embodiments of the present invention; Figure 6The images show a comparison of suspended particles on ceramic parts obtained using existing ceramic part cleaning methods and the ceramic part cleaning method provided in this embodiment of the invention. Detailed Implementation

[0010] To enable those skilled in the art to better understand the technical solution of the present invention, the ceramic cleaning method provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0011] This invention provides a method for cleaning ceramic parts, which can be applied to cleaning ceramic parts such as process kits, ceramic covers, and ceramic layers of electrostatic chucks in semiconductor equipment.

[0012] Specifically, please refer to Figure 1 Methods for cleaning ceramic parts include: The first cleaning process S1 involves using a chemical solution to dissolve particles on the ceramic parts. The first cleaning process can effectively remove particles from the surface of ceramic parts, especially particles in large blind holes, wrinkles, and non-welded gaps on the surface of ceramic parts.

[0013] The second cleaning process S2 uses a specified acidic solution to soften the particles on the corroded ceramic parts and eliminate the damaged layer on the ceramic parts; Since the presence of this damaged layer is one of the important sources of particle generation, this technology can effectively remove particles at the source compared to existing technologies, thereby greatly reducing the number of particles.

[0014] The third cleaning process, S3, uses ultrasonic cleaning to clean the ceramic parts in order to remove residual particles and solution from the ceramic parts.

[0015] Ultrasonic cleaning refers to the use of water waves generated by ultrasonic vibrations to clean particles from ceramic parts. The third cleaning process, S3, can thoroughly clean the ceramic parts, ultimately improving the cleaning effect.

[0016] Specifically, in the second cleaning process S2 described above, the specified acidic solution includes a fluoronitric acid solution, which is a mixture of hydrofluoric acid solution, nitric acid solution, and pure water. This solution can soften particles corroding the ceramic parts and eliminate the damaged layer on the ceramic parts. Of course, in practical applications, any other acidic solution that can achieve the same effect can also be used.

[0017] To enhance the softening and elimination effect on the damaged layer on the ceramic parts, the hydrofluoric acid solution, nitric acid solution, and pure water with a resistivity of 18 MΩ·cm can be mixed in a ratio of 1:1:1. The hydrofluoric acid solution contains a mass fraction of hydrofluoric acid greater than or equal to 5% and less than or equal to 15%, and the nitric acid solution contains a mass fraction of nitric acid greater than or equal to 25% and less than or equal to 35%.

[0018] To enhance the softening and elimination of the damaged layer on the ceramic part, optionally, the second cleaning process S2 is performed at least 4 times before the third cleaning process S3.

[0019] The specific implementation method of the second cleaning process S2 described above will be described in detail below. Specifically, as follows... Figure 2 As shown, the second cleaning process S2 specifically includes the following steps: S21. Rinse the ceramic parts with the specified acidic solution mentioned above; Optionally, in step S21, the ceramic part is rinsed at least three times with a specified acidic solution.

[0020] S22. Immerse the ceramic parts, which have been rinsed with the specified acidic solution, in the specified acidic solution. Optionally, in step S22 above, the immersion time of the ceramic part rinsed with the specified acidic solution in the specified acidic solution is greater than or equal to 10 minutes and less than or equal to 20 minutes.

[0021] S23. Rinse the soaked ceramic parts with pure water; Optionally, in step S23 above, the soaked ceramic parts are rinsed with pure water 3 to 5 times.

[0022] S24. Polishing tools made of nanomaterials are used to wipe ceramic parts that have been rinsed with pure water. Optionally, in step S24 above, a polishing tool made of nanomaterials is used to wipe the ceramic part after rinsing with pure water 3 to 5 times.

[0023] S25. Immerse the wiped ceramic parts in deionized water and perform ultrasonic cleaning. Optionally, in step S25 above, the cleaning time for ultrasonic cleaning is greater than or equal to 15 minutes and less than or equal to 30 minutes.

[0024] S26. Rinse the ceramic parts after ultrasonic cleaning with pure water.

[0025] Optionally, in step S26 above, the time for rinsing the ceramic part after ultrasonic cleaning with pure water is greater than or equal to 15 minutes and less than or equal to 60 minutes.

[0026] The specific implementation method of the first cleaning process S1 described above will be described in detail below. Specifically, as follows... Figure 3 As shown, the first cleaning process S1 specifically includes the following steps: S11. Wipe the ceramic parts with a lint-free cloth dampened with isopropyl ketone (IPA) solution; Step S11 above can make the ceramic part conductive to neutralize the charged ceramic particles on the ceramic part.

[0027] Optionally, the purity of the above isopropanone solution is 99.7%.

[0028] It should be noted that if the lint-free cloth has stains, it needs to be cleaned again to avoid damaging the texture and smooth surface of the ceramic part.

[0029] S12. Immerse the wiped ceramic parts in an alkaline solution and perform ultrasonic cleaning. Alkaline solutions can dissolve particles on ceramic parts, and combined with ultrasonic cleaning, this can effectively remove particles.

[0030] To effectively dissolve particles on ceramic parts and improve cleaning results, the alkaline solution can optionally be a KOH solution with a concentration percentage greater than or equal to 15% and less than or equal to 20%, and a temperature range greater than or equal to 75°C and less than or equal to 85°C. In step S12, the ultrasonic cleaning time ranges from greater than or equal to 1 hour to less than or equal to 3 hours. By setting the ultrasonic cleaning time within the above range, the particles on ceramic parts can be effectively dissolved, while avoiding damage to the sealing surface and hole edges of ceramic parts caused by excessive immersion time in the alkaline solution, which would affect the sealing performance of the parts.

[0031] In practical applications, a concentration detector can be used to detect the concentration of KOH solution, and the solution can be replaced or replenished according to the detected concentration value to achieve the target concentration value.

[0032] S13. Rinse the ceramic parts after ultrasonic cleaning with pure water. Optionally, in step S13 above, the ceramic parts after ultrasonic cleaning are rinsed with pure water 3 to 5 times.

[0033] S14. Immerse the rinsed ceramic parts in an acidic solution; Step S14 above can neutralize the alkaline solution remaining on the ceramic part, thereby reducing the corrosion of the ceramic part by the alkaline solution and preventing damage to the sealing surface and hole edge of the ceramic part by the alkaline solution.

[0034] Optionally, in step S14 above, the soaking time of immersing the rinsed ceramic parts in the acidic solution is greater than or equal to 5 minutes and less than or equal to 10 minutes.

[0035] Optionally, the acidic solution mentioned above is hydrochloric acid or fluoronitric acid solution, wherein fluoronitric acid solution has better dissolving effect with alkaline solution (such as KOH solution).

[0036] In addition, ultrasonic cleaning can be omitted in step S14 above.

[0037] S15. Rinse the ceramic parts after immersion in the acidic solution with pure water; S16. Immerse the rinsed ceramic parts in an alkaline solution.

[0038] Step S16 above can further dissolve the particles on the ceramic part.

[0039] Optionally, in step S16 above, the soaking time of the rinsed ceramic parts in the alkaline solution is greater than or equal to 1 hour and less than or equal to 3 hours. By setting the soaking time within the above range, the particles on the ceramic parts can be effectively dissolved, and the ceramic parts can be prevented from being soaked in the alkaline solution for too long, which would cause damage to the sealing surface and hole edges of the ceramic parts and affect the sealing performance of the parts.

[0040] The specific implementation method of the third cleaning process S3 described above will be described in detail below. Specifically, as follows... Figure 4 As shown, the third cleaning process S3 specifically includes the following steps: S31. Rinse the ceramic parts with pure water; Optionally, in step S31 above, the rinsing time is greater than or equal to 45 minutes and less than or equal to 60 minutes. S32. Immerse the rinsed ceramic parts in deionized water and perform ultrasonic cleaning. Step S32 described above can thoroughly clean the ceramic parts. Since ultrasonic cleaning using deionized water yields the most significant cleaning effect, completing the ultrasonic cleaning step ensures that the cleaning effect of the ceramic parts meets the process requirements. Moreover, the first cleaning process S1 and the second cleaning process S2 have already removed the damaged layer and suspended particles, thus compensating for the inability of ultrasonic cleaning to completely remove the damaged layer and suspended particles.

[0041] Optionally, in step S32 above, the ultrasonic cleaning time is greater than or equal to 30 minutes and less than or equal to 60 minutes.

[0042] Optionally, the resistivity of the above-mentioned deionized water is greater than or equal to 4 MΩ•cm.

[0043] S33. The ultrasonically cleaned ceramic parts are immersed in deionized water. During the immersion process, fresh deionized water is continuously introduced into the cleaning tank, and the deionized water in the cleaning tank is discharged by overflow. In step S33 above, by continuously introducing new deionized water into the cleaning tank during the soaking process and draining the deionized water from the cleaning tank by overflow, the deionized water can be kept in a circulating state, thereby further improving the cleaning effect.

[0044] Optionally, in step S33 above, the temperature of the deionized water is maintained within a range of greater than or equal to 32°C and less than or equal to 42°C.

[0045] S34. Blow-blow the soaked ceramic parts and bake them after blowing.

[0046] Optionally, the purging gas used in step S34 above includes nitrogen gas with a purity of 99.999%; the angle between the purging direction of the nitrogen gas and the surface of the ceramic part is greater than or equal to 30° and less than or equal to 45°, so as to avoid particles falling back onto the surface of the ceramic part.

[0047] Optionally, the ceramic parts are first thoroughly purged with dry nitrogen; then the purification furnace (or oven) is purged with dry nitrogen to dry its interior; finally, the ceramic parts are placed in the purged purification furnace (or oven) for baking.

[0048] The following comparative experiments will be conducted on ceramic parts obtained using existing ceramic part cleaning methods and the ceramic part cleaning methods provided in this embodiment of the invention. Specifically, the process of the existing ceramic part cleaning method is as follows: First, the ceramic part is immersed in an alkaline degreasing agent for 50-80 minutes, then rinsed in deionized water (using pressurized deionized water to spray all parts of the ceramic part surface); then, the ceramic part is immersed in an acidic solution for 5-10 minutes, then removed from the solution and immersed in deionized water again for the above rinsing; then, it is immersed in deionized water with a resistivity ≥4MΩ•cm at room temperature for ultrasonic cleaning for 10-15 minutes; then, the ceramic part is immersed in deionized water with a resistivity ≥8MΩ•cm for hot water immersion; finally, the ceramic part is dried with nitrogen and then baked to complete the entire cleaning process.

[0049] The ceramic part cleaning method provided in this embodiment of the invention includes the above three cleaning processes S1-S3, wherein the first cleaning process S1 includes the above steps S11-S16; the second cleaning process S2 includes the above steps S21-S26; and the third cleaning process S3 includes the above steps S31-S34.

[0050] Figure 5 These are comparative images of the damaged layers on ceramic parts obtained using existing ceramic part cleaning methods and the ceramic part cleaning method provided in this embodiment of the invention. (Combined with experimental data and...) Figure 5 As shown, ceramic parts obtained using existing ceramic part cleaning methods still have a machining damage layer on their surface, such as... Figure 5 As shown in Figure (a), the thickness of this damaged layer is 10 μm-30 μm, and its presence is one of the important sources of particle generation. In contrast, as... Figure 5 As can be seen from Figure (b), the ceramic parts obtained by the ceramic parts cleaning method provided in the embodiments of the present invention have their damaged layers significantly removed, thereby preventing the continuous shedding of particles from the ceramic parts during use on the equipment.

[0051] Figure 6 This is a comparison image showing suspended particles on ceramic parts obtained using existing ceramic part cleaning methods and the ceramic part cleaning method provided in this embodiment of the invention. (Combined with experimental data and...) Figure 6 As shown, ceramic parts cleaned using existing techniques still have suspended particles of 0.2μm to 1μm on their surface. Figure 6 As shown in Figure (a), the white dots in the black area are suspended particles. Furthermore, in existing ceramic cleaning methods, the number of particles falling onto the wafer per unit area during the process is ≥500 ea, far exceeding the particle count (<2 ea per unit area). Additionally, the liquid particle count (LPC) measurement on the ceramic part yielded a value of 75856 PA / cm². 2 In comparison, such as Figure 6 As shown in Figure (b), the number of white dots in the black area is significantly reduced. This indicates that the ceramic parts cleaned using the method provided in this embodiment of the invention have significantly fewer suspended particles. The number of particles per unit area on the wafer during the process is lower than the particle index (number of particles per unit area < 2ea), and the LPC measurement value is 729 PA / cm². 2 This is far less than the LPC detection value mentioned above in existing technologies.

[0052] The ceramic components in this embodiment of the invention include, for example, ceramic process kits for semiconductor devices. These ceramic process kits can be components made of ceramic materials, such as liners, dielectric windows, nozzles, sieves, main and secondary dielectric cylinders of a three-dimensional induction coil, and protective cylinders for the observation window. By improving the cleaning effect of these components, the problem of excessive ceramic particle count can be effectively solved, thereby improving chip yield.

[0053] In summary, the ceramic part cleaning method provided by this invention divides the cleaning process into three steps. The first step uses a chemical solution to dissolve particles on the ceramic part, effectively cleaning particles in large blind holes, wrinkles, and non-welding seams on the ceramic part surface. The second step uses a designated acidic solution to soften and corrode particles on the ceramic part and eliminate the damaged layer. Since the presence of this damaged layer is a major source of particle generation, this method effectively removes particles at the source compared to existing technologies, significantly reducing the number of particles. The third step uses ultrasonic cleaning to remove residual particles and solution (acidic or alkaline solution), enabling comprehensive cleaning of the ceramic part. Ultimately, this method effectively improves the cleaning effect, solves the problem of excessive ceramic particle count, and increases chip yield.

[0054] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for cleaning ceramic parts, characterized in that, include: The first cleaning process uses a chemical solution to dissolve the powdery particles generated during the molding process of the ceramic parts; The second cleaning process, which uses a specified acidic solution to soften and corrode particles on the ceramic part and remove the damaged layer on the ceramic part, includes: S21, rinsing the ceramic part with the specified acidic solution; S22, immersing the ceramic part after rinsing with the specified acidic solution in the specified acidic solution; S23, rinsing the immersed ceramic part with pure water; S24, wiping the ceramic part after rinsing with pure water using a polishing tool made of nanomaterials; S25, immersing the wiped ceramic part in deionized water and performing ultrasonic cleaning; S26, rinsing the ultrasonically cleaned ceramic part with pure water. The third cleaning process involves using ultrasonic cleaning to clean the ceramic parts in order to remove residual particles and solution from them.

2. The ceramic parts cleaning method according to claim 1, characterized in that, The specified acidic solution includes a fluoronitric acid solution, which is composed of a mixture of hydrofluoric acid solution, nitric acid solution, and pure water.

3. The ceramic parts cleaning method according to claim 2, characterized in that, The hydrofluoric acid solution, nitric acid solution, and pure water with a resistivity of 18 MΩ·cm are mixed in a ratio of 1:1:1; wherein, The hydrofluoric acid solution contains a hydrofluoric acid mass fraction ranging from greater than or equal to 5% to less than or equal to 15%. The nitric acid solution contains a nitric acid mass fraction in the range of greater than or equal to 25% and less than or equal to 35%.

4. The ceramic parts cleaning method according to claim 1, characterized in that, The second cleaning process is performed at least four times before the third cleaning process begins.

5. The ceramic parts cleaning method according to claim 1, characterized in that, In step S21, the ceramic part is rinsed with the specified acidic solution at least 3 times; in step S22, the ceramic part rinsed with the specified acidic solution is immersed in the specified acidic solution for a time greater than or equal to 10 minutes and less than or equal to 20 minutes; in step S23, the ceramic part is rinsed with pure water 3 to 5 times; in step S24, the ceramic part rinsed with pure water is wiped with a polishing tool made of nanomaterials 3 to 5 times; in step S25, the ultrasonic cleaning is performed for a time greater than or equal to 15 minutes and less than or equal to 30 minutes; in step S26, the ceramic part is rinsed with pure water for a time greater than or equal to 15 minutes and less than or equal to 60 minutes.

6. The ceramic parts cleaning method according to claim 1, characterized in that, The first cleaning process specifically includes the following steps: S11. Wipe the ceramic part with a lint-free cloth dampened with isopropyl ketone solution; S12. Immerse the wiped ceramic parts in an alkaline solution and perform ultrasonic cleaning. S13. Rinse the ceramic part after ultrasonic cleaning with pure water. S14. Immerse the rinsed ceramic parts in an acidic solution; S15. Rinse the ceramic parts after immersion in the acidic solution with pure water; S16. Immerse the rinsed ceramic parts in an alkaline solution.

7. The ceramic parts cleaning method according to claim 6, characterized in that, The isopropyl ketone solution has a purity of 99.7%; the alkaline solution is a KOH solution with a concentration percentage greater than or equal to 15% and less than or equal to 20%, and the temperature of the alkaline solution is greater than or equal to 75°C and less than or equal to 85°C; in step S12, the ultrasonic cleaning time is greater than or equal to 1 hour and less than or equal to 3 hours; in step S13, the ultrasonically cleaned ceramic part is rinsed with pure water 3 to 5 times; in step S14, the rinsed ceramic part is immersed in an acidic solution for a time greater than or equal to 5 minutes and less than or equal to 10 minutes; in step S15, the rinsed ceramic part is rinsed with pure water 3 to 5 times; in step S16, the rinsed ceramic part is immersed in an alkaline solution for a time greater than or equal to 1 hour and less than or equal to 3 hours.

8. The ceramic parts cleaning method according to claim 1, characterized in that, The third cleaning process specifically includes the following steps: S31. Rinse the ceramic part with pure water; S32. Immerse the rinsed ceramic parts in deionized water and perform ultrasonic cleaning. S33. The ceramic parts after ultrasonic cleaning are immersed in deionized water. During the immersion process, fresh deionized water is continuously introduced into the cleaning tank, and the deionized water in the cleaning tank is discharged by overflow. S34. The ceramic part after soaking is blown and then baked.

9. The ceramic parts cleaning method according to claim 8, characterized in that, In step S31, the rinsing time is greater than or equal to 45 min and less than or equal to 60 min; in step S32, the ultrasonic cleaning time is greater than or equal to 30 min and less than or equal to 60 min; in step S33, the soaking time is greater than or equal to 30 min and less than or equal to 60 min; in step S33, the temperature of the deionized water is maintained at greater than or equal to 32°C and less than or equal to 42°C; in step S34, the purging gas used includes nitrogen, and the purity of the nitrogen is 99.999%; the angle between the purging direction of the nitrogen and the surface of the ceramic part is greater than or equal to 30° and less than or equal to 45°.

10. The method for cleaning ceramic parts according to any one of claims 1-9, characterized in that, The ceramic component includes a ceramic process kit for semiconductor devices.

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