Fixed disc cleaning and maintaining method of silicon wafer grinding equipment

Abstract

The invention relates to a method for cleaning and maintaining a fixed disc of silicon wafer grinding equipment, which belongs to the technical field of silicon wafer processing and comprises the following operation steps of: 1, cleaning the fixed disc by using a cleaning tool; 2, in the equipment preheating stage, a cleaning procedure is executed at the temperature of 30 + / -2 DEG C; a two-stage cleaning method of dry-type cleaning and wet-type cleaning is adopted, and after cleaning, the number of residual particles is required to be smaller than 50 / cm through verification of an on-line monitoring unit. Thirdly, periodic fixed disc finishing is carried out, and diamond grinding wheel finishing wheel compensation machining is carried out every 72 + / -2 hours; and after finishing, the surface roughness Ra is less than or equal to 0.02 mu m, and the flatness error is less than 0.3 mu m. The key problems that in the silicon wafer grinding process, the grinding precision is unstable, and the silicon wafer yield is reduced due to the problems of particle residues, surface abrasion, planeness reduction and the like of the fixed disc are solved. And a standardized cleaning process and periodic accurate finishing are adopted to ensure that the fixed disc is always in an optimal working state, so that ultrahigh precision and quality of silicon wafer grinding are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon wafer processing, in particular to a method for cleaning and maintaining a fixed disc of a silicon wafer grinding device. BACKGROUND

[0002] In the current silicon wafer grinding process, due to problems such as residual grinding debris and accumulated micro-damage on the surface of the fixed disc, the flatness (TTV) of the silicon wafer is long-term in a critical state of 1.4-1.5 μm, and frequently exceeds the control line of 1.5 μm. The traditional cleaning method has the following defects: 1: Nanoscale grinding particles embedded in the grooves of the fixed disc cannot be completely removed by cleaning tools.

[0003] 2: Lack of standardized cleaning cycle and quantitative trimming strategy. SUMMARY

[0004] The present application mainly solves the problems in the prior art and provides a method for cleaning and maintaining a fixed disc of a silicon wafer grinding device, which solves the key problems of unstable grinding precision and reduced silicon wafer yield caused by problems such as residual particles, surface wear and flatness reduction of the fixed disc in the silicon wafer grinding process. Through innovative cleaning tool design and maintenance strategy optimization, stable control of silicon wafer flatness CPK≥1.67 is achieved. Standardized cleaning process and periodic precise trimming ensure that the fixed disc is always in the best working state, thereby ensuring the ultra-high precision and quality of silicon wafer grinding.

[0005] The above technical problems of the present application are mainly solved by the following technical scheme: A method for cleaning and maintaining a fixed disc of a silicon wafer grinding device, comprising the following operation steps: Step 1: Use a cleaning tool to clean the fixed disc. The most basic physical process to remove large particles or impurities.

[0006] Step 2: Perform the cleaning program at a temperature of 30±2℃ during the preheating stage of the device. Clean at the preheating stage (30±2℃), use the principle of thermal expansion and contraction to make the residues in the grooves of the fixed disc more easily loose and removed, and at the same time avoid the risks brought by cleaning at high speed or high temperature.

[0007] Two-stage cleaning method of dry cleaning and wet cleaning. Dry cleaning: physically scraping off stubborn particles in the grooves. Wet cleaning: use ultrapure water to rinse, dissolve and remove small particles and chemical residues.

[0008] After cleaning, the residual particle count is verified by an online monitoring unit, which is required to be < 50 / cm2. Through online monitoring, closed-loop control of the cleaning process is achieved, ensuring that each cleaning meets the standard and avoiding the uncertainty of relying on experience. 50 / cm2 is an extremely high cleanliness requirement, suitable for high-end semiconductor manufacturing.

[0009] Third step: Periodic conditioning, diamond wheel dressing and compensation processing are performed every 72±2 hours to restore the geometric accuracy lost due to grinding consumption; after conditioning, the surface roughness Ra is ≤0.02μm, ensuring that the conditioning plate surface is extremely smooth and will not scratch the silicon wafer, and can uniformly transmit the grinding pressure. The flatness error is <0.3μm, and the error control of 0.3μm is the basis for ensuring uniform grinding. For large-size silicon wafers of 300mm or even 450mm, small flatness errors of the conditioning plate will be magnified, resulting in uneven silicon wafer thickness (TTV, Total Thickness Variation).

[0010] Every 72±2 hours, based on the scientific cycle set by the device operation rules and wear rate, it is neither too frequent to increase cost, nor too long to cause precision to decrease.

[0011] As a preferred embodiment, the dry cleaning uses a cleaning tool to perform groove cleaning at a pressure of 3-5N and a speed of 20mm / s. Too small pressure cannot effectively remove residues, and too large pressure may damage the conditioning plate surface. Too fast speed may result in incomplete cleaning, and too slow speed affects efficiency. Fixing these two parameters ensures the consistency and repeatability of dry cleaning operations, avoiding differences between different operators.

[0012] As a preferred embodiment, the wet cleaning sprays ultrapure water into the cleaned groove, rinses it to a resistivity of ≥18MΩ·cm, and then blows it dry with nitrogen in a dust-free environment. When the water resistivity of the rinsing discharge reaches 18MΩ·cm, it indicates that the dissolved ion impurities in the water are extremely low, and the conditioning plate groove has been thoroughly cleaned.

[0013] As a preferred embodiment, after cleaning and drying are completed, the conditioning plate flatness error is checked, and the deviation value is measured using a laser interferometer; when the error exceeds 5μm, mechanical conditioning or replacement is required to ensure grinding accuracy.

[0014] 5μm is a "warning line" or "failure line". When the flatness error accumulates to this extent, regular periodic conditioning may not be effective in restoring it, or it may mean that the conditioning plate has undergone non-uniform wear, deformation or damage. At this time, more aggressive measures, such as mechanical conditioning or replacement, need to be taken to ensure that the device returns to the reference state.

[0015] As preferred, the trimming parameters are dynamically adjusted, the rotating speed in the initial stage is 800 rpm, and the feed amount is 0.5 mu m / pass, the lower rotating speed and the larger feed amount are suitable for quickly removing the macro-unevenness on the surface and the wear layer, and the efficiency of the preliminary trimming is improved. The rotating speed in the stable stage is 1200 rpm, and the feed amount is 0.2 mu m / pass, the higher rotating speed and the smaller feed amount are used for fine trimming and polishing. The high rotating speed can obtain better surface finish, and the small feed amount can accurately control the removal amount, and finally the strict requirements of Ra≤0.02 mu m and <0.3 mu m flatness are met.

[0016] As preferred, the cleaning tool comprises a short split-type stainless steel cleaning cutter or a long stainless steel cleaning cutter. Different sizes of the chuck plate or different positions of the groove can require different lengths of the cutter. The split-type design can facilitate replacement of the cutter head or adaptation to different angles of cleaning, thereby improving the applicability and maintenance convenience of the tool.

[0017] As preferred, when the chuck plate has scratches or wear, the machine should be immediately stopped for inspection; according to the chip polishing equipment maintenance scheme, the slight damage can be repaired by using a nano polishing liquid; and the serious wear requires re-plating in the factory.

[0018] The present application can achieve the following effects: The present application provides a chuck plate cleaning and maintenance method of a silicon wafer grinding equipment, and compared with the prior art, solves the key problems of unstable grinding precision and reduced silicon wafer yield caused by problems such as residual particles, surface wear and flatness reduction of the chuck plate in the silicon wafer grinding process. By using a standardized cleaning process and periodic accurate trimming, the chuck plate is ensured to be always in the best working state, thereby ensuring the ultra-high precision and quality of the silicon wafer grinding.

[0019] Systematicness and completeness: from daily cleaning, periodic trimming to emergency treatment, a maintenance management system covering the whole life cycle of the chuck plate is formed.

[0020] High precision and quantitative control: all key steps (cleaning effect, trimming result and state monitoring) are provided with clear and quantifiable technical indexes (such as particle number, roughness, flatness and resistivity), so that the maintenance work is changed from “experience-driven” to “data-driven”, and the high stability and high reliability are ensured.

[0021] Timing selection: cleaning in the preheating stage of the equipment makes use of the physical principle, and the work is done twice the result with half the effort.

[0022] Method combination: the cleaning method of “dry and wet combination” takes into account the advantages of physical removal and chemical washing.

[0023] Process optimization: dynamic adjustment of trimming parameters realizes the balance between efficiency and precision.

[0024] Practicality and operability: detailed provisions are made for tools, parameters, standards and decision-making processes, so that the method can be accurately implemented by front-line technicians, ensuring the consistency of operation.

[0025] Cost-effective awareness: through hierarchical processing (minor damage on-site repair, serious damage returned to the factory), the maintenance cost is optimized, and the "one-size-fits-all" high-cost processing method is avoided. DETAILED DESCRIPTION

[0026] The technical solutions of the application will be further specifically explained by examples.

[0027] Embodiment: A cleaning and maintenance method for the fixed disc of a silicon wafer grinding device, comprising the following operation steps: First step: clean the fixed disc with a cleaning tool. The cleaning tool includes a short split-type stainless steel cleaning tool or a long stainless steel cleaning tool.

[0028] Second step: Perform the cleaning program at a temperature of 30±2℃ during the preheating stage of the equipment; use a two-stage cleaning method of dry cleaning and wet cleaning, and verify the residual particle count <50 / cm² through the online monitoring unit after cleaning.

[0029] Dry cleaning uses a cleaning tool to clean the groove at a pressure of 3-5N and a speed of 20mm / s.

[0030] Wet cleaning sprays ultrapure water into the cleaned groove, rinses it to a resistivity of ≥18MΩ·cm, and blows it dry with nitrogen in a dust-free environment.

[0031] After cleaning and drying, check the flatness error of the fixed disc, measure the deviation value with a laser interferometer; when the error exceeds 5μm, mechanical finishing or replacement is required to ensure grinding accuracy.

[0032] Third step: Periodic fixed disc finishing, diamond grinding wheel finishing compensation processing is performed every 72±2 hours, and the finishing parameters are dynamically adjusted; the initial stage speed is 800rpm, and the feed amount is 0.5μm / pass; the stable stage speed is 1200rpm, and the feed amount is 0.2μm / pass. After finishing, the surface roughness Ra≤0.02μm, and the flatness error <0.3μm.

[0033] When the fixed disc has scratches or wear, it should be immediately stopped and checked; according to the chip polishing equipment maintenance scheme, minor damage can be repaired with nanoscale polishing liquid; serious wear requires re-plating at the factory.

[0034] The overall process can be summarized as three major links: (1) Daily cleaning: Adopting a two-stage method of "dry-wet combination", which is executed at a specific temperature and the cleaning effect is quantified through online monitoring.

[0035] (2) Periodic trimming: Diamond grinding wheel trimming is performed on the fixed disc at a fixed period (about 72 hours) to restore its surface roughness and flatness, and dynamic parameters are used to optimize the trimming process.

[0036] (3) State monitoring and emergency treatment: After cleaning and during daily operation, the state of the fixed disc is continuously monitored and damage exceeding the tolerance range is classified for treatment (polishing repair or factory coating).

[0037] In summary, the cleaning and maintenance method of the fixed disc of the silicon wafer grinding equipment solves the key problems of unstable grinding precision and reduced silicon wafer yield caused by residual particles, surface wear, and flatness decline of the fixed disc during silicon wafer grinding. By adopting a standardized cleaning process and periodic precise trimming, the fixed disc is always in the best working condition, thereby ensuring the ultra-high precision and quality of silicon wafer grinding. The combination of preventive maintenance and precise repair establishes a complete closed-loop management system from daily cleaning to periodic trimming and emergency treatment.

[0038] The flatness of the silicon wafer is optimized from 1.45±0.1μm to 0.5±0.05μm initially (1.0±0.05μm at the end). This greatly improves the stability of the equipment processing, and the service life of the fixed disc is extended from 110,000 to 300,000, and the overall equipment efficiency (OEE) is improved by 23.6%.

[0039] The above is only a specific embodiment of the present application, but the structural features of the present application are not limited to this. Any changes or modifications made by those skilled in the art within the scope of the present application are covered by the patent scope of the present application.

Claims

1. A method for cleaning and maintaining the mounting plate of a silicon wafer grinding equipment, characterized in that... The following steps are included: Step 1: Clean the plate using cleaning tools; Step 2: During the equipment preheating stage, the cleaning procedure is carried out at a temperature of 30±2℃. A two-stage cleaning method of dry cleaning and wet cleaning is adopted. After cleaning, the residual particle count is verified by the online monitoring unit and is required to be <50 / cm². Step 3: Periodic plate dressing, with diamond grinding wheel dressing compensation machining performed every 72±2 hours; after dressing, the surface roughness Ra≤0.02μm, and the flatness error<0.3μm.

2. The method for cleaning and maintaining the wafer grinding plate of the silicon wafer grinding equipment according to claim 1, characterized in that: The dry cleaning method uses cleaning tools to clean the trenches with a pressure of 3-5N and a speed of 20mm / s.

3. The method for cleaning and maintaining the wafer grinding plate of the silicon wafer grinding equipment according to claim 1, characterized in that: The wet cleaning process involves spraying ultrapure water into the cleaned trench, rinsing until the resistivity is ≥18MΩ·cm, and then drying it with nitrogen in a dust-free environment.

4. The method for cleaning and maintaining the wafer grinding plate of the silicon wafer grinding equipment according to claim 3, characterized in that: After cleaning and drying, check the flatness error of the plate and measure the deviation value using a laser interferometer. When the error exceeds 5μm, mechanical repair or replacement is required to ensure grinding accuracy.

5. The method for cleaning and maintaining the wafer grinding plate of the silicon wafer grinding equipment according to claim 1, characterized in that: The trimming parameters are dynamically adjusted. In the initial stage, the rotational speed is 800 rpm and the feed rate is 0.5 μm / pass. In the stable stage, the rotational speed is 1200 rpm and the feed rate is 0.2 μm / pass.

6. The method for cleaning and maintaining the wafer grinding plate of the silicon wafer grinding equipment according to claim 1, characterized in that: The cleaning tools include short, split-type stainless steel cleaning knives or long stainless steel cleaning knives.

7. The method for cleaning and maintaining the wafer grinding plate of the silicon wafer grinding equipment according to claim 1, characterized in that: When scratches or wear appear on the die plate, the machine should be stopped immediately for inspection. According to the chip polishing equipment maintenance plan, minor damage can be repaired with nano-level polishing fluid; severe wear requires returning to the factory for replating.