A process for chemical mechanical planarization of recoverable wafers
By using cerium oxide polishing slurry and high-pressure water gun in the chemical mechanical planarization process of recyclable wafers, the problems of slow polishing rate and high material consumption in the prior art have been solved, achieving efficient wafer surface planarization and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANJI MICROELECTRONICS TECH (SHANGHAI) CO LTD
- Filing Date
- 2024-12-30
- Publication Date
- 2026-06-30
AI Technical Summary
In the current technology for chemical mechanical planarization of recyclable wafers, silicon dioxide polishing slurry is difficult to meet the production capacity requirements under high pressure and is prone to crystallization, resulting in wafer scratches and large equipment wear. While cerium oxide polishing slurry is fast, byproducts are easy to remain, affecting the polishing effect.
By using cerium oxide polishing slurry in combination with high-pressure water guns and dressing tools, and through steps such as pre-rinsing, polishing, water polishing, and scraping, the polishing process is optimized to avoid the accumulation of by-products and wafer scratches, thereby reducing consumable consumption.
It increases the grinding rate of recyclable wafers, reduces wear on polishing pads and dressers, lowers production costs, and improves production efficiency.
Smart Images
Figure CN122299512A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor manufacturing processes, specifically to a process method for chemically and mechanically planarizing recyclable wafers. Background Technology
[0002] In semiconductor device manufacturing, recyclable wafers refer to silicon wafers that can be reused after the thin film layers deposited on them are removed. Recyclable wafers are commonly used for process and equipment testing in semiconductor manufacturing. Generally, the required thin film layers are deposited sequentially on the recyclable wafer substrate for reuse. Currently, the used wafers can be reused by removing the oxide and polysilicon layers on the silicon wafer through chemical mechanical planarization (CMP). Currently, silica polishing slurries are commonly used for planarization during CMP of recyclable wafers. However, when polishing recyclable wafers with a large total thickness of oxide / polysilicon layers, due to the characteristics of silica polishing slurries, even with high particle concentrations and high pressure (>350 hPa), the polishing speed is still insufficient to meet the increasing production capacity demands. Simultaneously, the high particle concentration and pressure make the solution prone to crystallization, resulting in scratches on the silicon wafer and significant wear on the polishing pads and dressers, increasing maintenance time and costs.
[0003] Cerium oxide polishing slurry boasts advantages such as good stability, fast polishing speed, wide applicability, and high-quality wafer surface finish after polishing, making it commonly used for polishing oxide and polysilicon layers. Therefore, using cerium oxide polishing slurry to polish recyclable wafers can achieve a relatively fast polishing rate under low particle concentration and low pressure conditions, thus avoiding problems such as solution crystallization, wafer scratching, and high equipment wear. However, during cerium oxide solution polishing, due to its excessively fast polishing rate, byproducts easily remain on the polishing pad, affecting the polishing effect. Furthermore, due to the characteristics of cerium oxide polishing slurry, it tends to adhere to the wafer surface, generating surface particle defects.
[0004] To address the above issues, this invention provides a process for polishing recyclable wafers using cerium oxide polishing slurry. This process allows for the rapid removal of the silicon oxide / polysilicon layer from the recyclable surface using cerium oxide polishing slurry, avoiding byproduct residues and surface defects caused by particles adhering to the wafer surface. This achieves a better polishing effect on the wafer surface while reducing production and maintenance costs. Summary of the Invention
[0005] To overcome the aforementioned technical problems, this invention provides a process for chemically and mechanically planarizing recyclable wafers. This process effectively utilizes cerium oxide polishing slurry to grind recyclable wafers, thereby solving problems such as slow grinding rates, high consumption of consumables like polishing pads and dressers, and easy crystallization of high-concentration silica polishing slurries for recyclable wafers with large thicknesses and silicon oxide / polysilicon layers on the surface, while avoiding defects such as polishing pad byproduct accumulation and wafer scratches caused by the excessively fast polishing speed and difficult-to-clean characteristics of cerium oxide polishing slurry. This reduces production costs and improves production efficiency.
[0006] This invention discloses a process for chemically and mechanically planarizing recyclable wafers, the process comprising:
[0007] S1: Provide a recyclable wafer placed on a polishing pad, wherein an oxide layer is formed on the wafer, and a polycrystalline silicon layer is formed on the oxide layer, the total deposition thickness of the oxide layer and the polycrystalline silicon layer being greater than 2000 nm; provide a cerium oxide polishing slurry, the polishing rate of both the oxide layer and the polycrystalline silicon layer being greater than 500 nm / min; provide an alkaline solution containing ammonia.
[0008] S2: Pre-rinse the recyclable wafer using a high-pressure water gun;
[0009] S3: Pre-flow the recyclable wafer using the cerium oxide polishing slurry;
[0010] S4: Polish the recyclable wafer using the cerium oxide polishing slurry, while simultaneously scraping the polishing pad with a dresser;
[0011] S5: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer, and perform water polishing, while the finisher scrapes and washes the polishing pad.
[0012] S6: Polish the recyclable wafer again using the cerium oxide polishing slurry, without the trimmer working;
[0013] S7: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer again, and perform water polishing, while the dressing device scrapes and washes the polishing pad.
[0014] S8: Polish the recyclable wafer using cerium oxide polishing slurry, while the finisher scrapes and washes the polishing pad;
[0015] S9: High-pressure water gun is used to clean the polishing pad and the surface of the recyclable wafer, and the polishing pressure is reduced during water polishing;
[0016] S10: Remove the recyclable wafer from the polishing pad, rinse it with a high-pressure water gun, and increase the pressure of the dressing device to scrape the polishing pad.
[0017] S11: Grind the recyclable wafer using an alkaline solution and a soft polishing pad.
[0018] Optionally, the process is performed using a chemical mechanical polishing (CMP) machine, which includes a polishing pad, a polishing head, and a soft polishing pad. During polishing, the polishing head and the polishing pad rotate simultaneously.
[0019] Optionally, in step S2, the flow rate of the high-pressure water gun is greater than 10L / min, the rotation speed of the polishing head is 20r / min to 40r / min, the rotation speed of the polishing pad is 50r / min to 70r / min, and the duration is 5 to 10s.
[0020] Optionally, in step S3, the flow rate of the cerium oxide polishing slurry is 300 ml / min to 500 ml / min, the rotation speed of the polishing head is 50 to 70 r / min, the rotation speed of the polishing pad is 50 r / min to 70 r / min, and the duration is 5 to 10 seconds.
[0021] Optionally, in steps S4, S6, and S8, the flow rate of the cerium oxide polishing slurry is 300 ml / min to 500 ml / min, the rotation speed of the polishing head is 80 to 110 r / min, the pressure of the polishing head is 250 hpa to 350 hpa, the rotation speed of the polishing pad is 80 r / min to 110 r / min, and the duration is 60 to 100 s.
[0022] Optionally, in steps S5 and S7, the high-pressure water gun flow rate is 10L / min, the polishing head rotation speed is 80-110r / min, the polishing head pressure is 250hpa-350hpa, the polishing pad rotation speed is 80-110r / min, and the duration is 10-15s.
[0023] Optionally, in step S9, the high-pressure water gun flow rate is 10L / min, the polishing head rotation speed is 50-70r / min, the polishing head pressure is 50hpa-150hpa, the polishing pad rotation speed is 50-70r / min, and the duration is 20-40s.
[0024] Optionally, in steps S4, S5, S7, and S8, the dressing speed is 50–100 r / min, the dressing pressure is 20–30 N, and the dressing scraping speed is once every 6 seconds.
[0025] Optionally, in step S10, the high-pressure water gun flow rate is 10L / min, the polishing pad rotation speed is 70-90r / min, and the duration is 20-40s; the dressing speed is 50-100r / min, the dressing pressure is 35-50N, and the dressing is reciprocated for scraping 3-5 times.
[0026] Optionally, in step S11, the alkaline solution is a solution containing ammonia, the solution flow rate is 300-500 ml / min, the polishing head rotation speed is 50-70 r / min, the polishing head pressure is 50 hpa-150 hpa, the polishing pad rotation speed is 50-70 r / min, and the duration is 50-70 s.
[0027] Optionally, after performing step S11, the process further includes cleaning and drying the recyclable wafer.
[0028] The following technical effects can be achieved through the solution of the present invention:
[0029] 1. Significantly improves the grinding rate of recyclable wafers with thicker thickness and deposited silicon oxide / polysilicon layers, and the grinding particles are less prone to crystallization, reducing the consumption of consumables such as polishing pads and dressers.
[0030] 2. The process of this invention, which utilizes high-pressure water rinsing and a dressing tool to scrape and clean the polishing pad, avoids the need for cerium dioxide polishing.
[0031] The excessively fast polishing speed and lack of cleaning properties of the photopolymer solution lead to defects such as polishing pad byproduct accumulation and wafer scratches, which reduce production costs and improve production efficiency. Attached Figure Description
[0032] Figure 1 A flowchart of a process for chemically and mechanically planarizing recyclable wafers in accordance with an embodiment of the present invention;
[0033] Figure 2 A comparison chart of the polishing rates of cerium oxide polishing slurry and silica polishing slurry;
[0034] Figure 3 A comparison of the average polishing rate as polishing pad life varies when polishing recyclable wafers with cerium oxide polishing slurry and silicon dioxide polishing slurry.
[0035] Figure 4 This is a graph showing the change in wafer polishing rate as the polishing pad life varies during cerium oxide polishing using the method of this invention.
[0036] Figure 5 Comparison of the time required to polish recyclable wafers using cerium oxide polishing slurry and silicon dioxide polishing slurry;
[0037] Figure 6 Comparison of wafer surface particles after grinding with cerium oxide polishing slurry without and with the method of this invention;
[0038] Figure 7 This is a graph showing the change in the number of particles on the wafer surface after grinding with cerium oxide polishing slurry using the method of the present invention, as the lifespan of the polishing pad changes. Detailed Implementation
[0039] The advantages of the present invention are further illustrated below through specific embodiments.
[0040] Figure 1 A flow chart of a process for chemically and mechanically planarizing recyclable wafers is shown. The process includes:
[0041] S1: Provide a recyclable wafer placed on a polishing pad, wherein an oxide layer is formed on the wafer, and a polycrystalline silicon layer is formed on the oxide layer, the total deposition thickness of the oxide layer and the polycrystalline silicon layer being greater than 2000 nm; provide a cerium oxide polishing slurry, the polishing rate of both the oxide layer and the polycrystalline silicon layer being greater than 500 nm / min; provide an alkaline solution containing ammonia.
[0042] S2: Pre-rinse the recyclable wafer using a high-pressure water gun;
[0043] S3: Pre-flow the recyclable wafer using the cerium oxide polishing slurry;
[0044] S4: Polish the recyclable wafer using the cerium oxide polishing slurry, while simultaneously scraping the polishing pad with a dresser;
[0045] S5: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer, and perform water polishing, while the finisher scrapes and washes the polishing pad.
[0046] S6: Polish the recyclable wafer again using the cerium oxide polishing slurry, without the trimmer working;
[0047] S7: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer again, and perform water polishing, while the dressing device scrapes and washes the polishing pad.
[0048] S8: Polish the recyclable wafer using cerium oxide polishing slurry, while simultaneously cleaning the polishing pad with a dresser;
[0049] S9: High-pressure water gun is used to clean the polishing pad and the surface of the recyclable wafer, and the polishing pressure is reduced during water polishing;
[0050] S10: Remove the recyclable wafer from the polishing pad, rinse it with a high-pressure water gun, and increase the pressure of the dressing device to scrape the polishing pad.
[0051] S11: Grind the recyclable wafer using an alkaline solution and a soft polishing pad.
[0052] In an optional embodiment of the present invention, the chemical mechanical planarization process for recyclable wafers is performed using a chemical mechanical polishing (CMP) machine commonly used in the semiconductor polishing field. The CMP machine includes a polishing pad, a polishing head, and a soft polishing pad. During polishing, the polishing head and polishing pad rotate simultaneously at a certain speed, with a high-pressure water gun and a corrector used as auxiliary methods for CMP polishing. The process specifically includes:
[0053] Step S1: Provide a recyclable wafer, place it on a polishing pad, an oxide layer is formed on the wafer, a polycrystalline silicon layer is formed on the oxide layer, and the total deposition thickness of the oxide layer and the polycrystalline silicon layer is greater than 2000 nm; provide a cerium oxide polishing slurry, with a polishing rate of greater than 500 nm / min for both the oxide layer and the polycrystalline silicon layer; provide an alkaline solution containing ammonia.
[0054] Step S2: Pre-rinse the recyclable wafer using a high-pressure water gun. Set the flow rate of the high-pressure water gun to be greater than 10 L / min, the rotation speed of the polishing head to 20 r / min to 40 r / min, and the rotation speed of the polishing pad to 50 r / min to 70 r / min during rinsing, and continue this process for 5 to 10 seconds.
[0055] Step S3: Pre-flow the recyclable wafer using the cerium oxide polishing slurry; set the cerium oxide polishing slurry flow rate to 300ml / min~500ml / min, the polishing head rotation speed to 50~70r / min, and the polishing pad rotation speed to 50r / min~70r / min, for 5~10s.
[0056] Step S4: Polish the recyclable wafer using the cerium oxide polishing slurry, while simultaneously scraping the polishing pad with a dresser; set the cerium oxide polishing slurry flow rate to 300ml / min~500ml / min, the polishing head rotation speed to 80~110r / min, the polishing head pressure to 250hpa~350hpa, the polishing pad rotation speed to 80r / min~110r / min, for 60~100s; set the dresser rotation speed to 50~100r / min, the dresser pressure to 20~30N, and the dresser scraping speed to be once every 6s.
[0057] Step S5: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer, and perform water polishing. Simultaneously, the dresser scrapes and washes the polishing pad. Set the high-pressure water gun flow rate to 10 L / min, the polishing head rotation speed to 80–110 r / min, the polishing head pressure to 250 hPa–350 hPa, and the polishing pad rotation speed to 80–110 r / min, for 10–15 seconds. Refer to step S4 for dresser parameter settings.
[0058] Step S6: Polish the recyclable wafer again using the cerium oxide polishing slurry. The dresser is not working. Set other parameters as in step S4.
[0059] Step S7: Rinse the polishing pad and the surface of the recyclable wafer again with a high-pressure water gun, and perform water polishing. At the same time, the dresser scrapes and washes the polishing pad; refer to step S5 for parameter settings. Refer to step S4 for dresser parameter settings.
[0060] Step S8: Polish the recyclable wafer using cerium oxide polishing slurry, while simultaneously cleaning the polishing pad with a dresser; the parameter settings are the same as in steps S4 and S6, and the details are as described in step S4. The dresser parameter settings are also described in step S4.
[0061] Step S9: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer, and reduce the polishing pressure to perform water polishing; set the high-pressure water gun flow rate to 10L / min, the polishing head rotation speed to 50-70r / min, the polishing head pressure to 50hpa-150hpa, and the polishing pad rotation speed to 50-70r / min, for 20-40s.
[0062] Step S10: Remove the recyclable wafer from the polishing pad, rinse it with a high-pressure water gun, and increase the pressure of the dresser to scrape the polishing pad; set the high-pressure water gun flow rate to 10L / min, the polishing pad rotation speed to 70-90r / min, and continue for 20-40s; the dresser rotation speed to 50-100r / min, the dresser pressure to 35-50N, and the dresser scrapes back and forth 3-5 times.
[0063] Step S11: Polish the recyclable wafer using an alkaline solution and a soft polishing pad. The alkaline solution is an ammonia-containing solution with a flow rate of 300–500 ml / min, the polishing head rotation speed is 50–70 r / min, the polishing head pressure is 50 hpa–150 hpa, the polishing pad rotation speed is 50–70 r / min, and the duration is 50–70 s.
[0064] Repeatability experiments were conducted in the schemes provided in the above embodiments, and comparative experiments were performed using silicon dioxide instead of cerium oxide. The data were then processed to obtain... Figures 2-5 The experimental results are shown.
[0065] See Figures 2-5 In the example of the present invention, the cerium oxide polishing slurry has a much higher grinding rate on recyclable wafers than the silicon dioxide polishing slurry, effectively improving the grinding efficiency by about 50%, and the average polishing rate remains stable as the polishing pad life changes.
[0066] like Figure 6 , Figure 7In the example, after the recyclable wafer is polished with cerium oxide polishing slurry using the process described in the above embodiments of the present invention, the number of particles on the wafer surface can be effectively reduced by about 80%, and the number of particles on the wafer surface is less than 100 with changes in padlife.
[0067] In summary, the chemical mechanical planarization process for recyclable wafers provided by this invention reduces byproduct accumulation and wafer scratches by timely rinsing and scraping of the polishing pad, without sacrificing the grinding rate of the cerium oxide polishing slurry. This method effectively utilizes the cerium oxide polishing slurry to grind recyclable wafers, significantly improving the grinding rate of thicker recyclable wafers with deposited silicon oxide / polysilicon layers. Furthermore, the grinding particles are less prone to crystallization, reducing the consumption of consumables such as polishing pads and dressers. Simultaneously, it avoids the defects such as byproduct accumulation and wafer scratches caused by the excessively fast polishing speed and difficult-to-clean characteristics of cerium dioxide polishing slurry, thus reducing production costs and improving production efficiency.
[0068] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A process for chemical mechanical planarization of a recoverable wafer, characterized by, The process includes: S1: Provide a recyclable wafer placed on a polishing pad, wherein an oxide layer is formed on the wafer, and a polycrystalline silicon layer is formed on the oxide layer, the total deposition thickness of the oxide layer and the polycrystalline silicon layer being greater than 2000 nm; provide a cerium oxide polishing slurry, the polishing rate of both the oxide layer and the polycrystalline silicon layer being greater than 500 nm / min; provide an alkaline solution containing ammonia. S2: Pre-rinse the recyclable wafer using a high-pressure water gun; S3: Pre-flow the recyclable wafer using the cerium oxide polishing slurry; S4: Polish the recyclable wafer using the cerium oxide polishing slurry, while simultaneously scraping the polishing pad with a dresser; S5: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer, and perform water polishing, while the finisher scrapes and washes the polishing pad. S6: Polish the recyclable wafer again using the cerium oxide polishing slurry, without the trimmer working; S7: Use a high-pressure water gun to rinse the polishing pad and the surface of the recyclable wafer again, and perform water polishing, while the dressing device scrapes and washes the polishing pad. S8: Polish the recyclable wafer using cerium oxide polishing slurry, while the finisher scrapes and washes the polishing pad; S9: High-pressure water gun is used to clean the polishing pad and the surface of the recyclable wafer, and the polishing pressure is reduced during water polishing; S10: Remove the recyclable wafer from the polishing pad, rinse it with a high-pressure water gun, and increase the pressure of the dressing device to scrape the polishing pad. S11: Grind the recyclable wafer using an alkaline solution and a soft polishing pad.
2. The process for chemical mechanical planarization of a recoverable wafer of claim 1 wherein, The process is performed using a chemical mechanical polishing (CMP) machine, which includes a polishing pad, a polishing head, and a soft polishing pad. During polishing, the polishing head and the polishing pad rotate simultaneously.
3. The process for chemical mechanical planarization of a recoverable wafer of claim 2 wherein, In step S2, the flow rate of the high-pressure water gun is greater than 10L / min, the rotation speed of the polishing head is 20r / min to 40r / min, the rotation speed of the polishing pad is 50r / min to 70r / min, and the duration is 5 to 10s.
4. The process for chemical mechanical planarization of a recoverable wafer of claim 2, wherein, In step S3, the flow rate of the cerium oxide polishing slurry is 300 ml / min to 500 ml / min, the rotation speed of the polishing head is 50 to 70 r / min, the rotation speed of the polishing pad is 50 r / min to 70 r / min, and the duration is 5 to 10 seconds.
5. The process for chemical mechanical planarization of a recoverable wafer of claim 2 wherein, In steps S4, S6, and S8, the flow rate of the cerium oxide polishing slurry is 300 ml / min to 500 ml / min, the rotation speed of the polishing head is 80 to 110 r / min, the pressure of the polishing head is 250 hpa to 350 hpa, the rotation speed of the polishing pad is 80 r / min to 110 r / min, and the duration is 60 to 100 s.
6. The process for chemical mechanical planarization of a recoverable wafer of claim 2 wherein, In steps S5 and S7, the high-pressure water gun flow rate is 10L / min, the polishing head rotation speed is 80-110r / min, the polishing head pressure is 250hpa-350hpa, the polishing pad rotation speed is 80-110r / min, and the duration is 10-15s.
7. The process for chemical mechanical planarization of a recoverable wafer of claim 2 wherein, In step S9, the high-pressure water gun flow rate is 10L / min, the polishing head rotation speed is 50-70r / min, the polishing head pressure is 50hpa-150hpa, the polishing pad rotation speed is 50-70r / min, and the duration is 20-40s.
8. The process for chemical mechanical planarization of a recoverable wafer of claim 1 wherein, In steps S4, S5, S7, and S8, the dressing speed is 50–100 r / min, the dressing pressure is 20–30 N, and the dressing scraping speed is once every 6 seconds.
9. The process for chemical mechanical planarization of a recoverable wafer of claim 1 wherein, In step S10, the high-pressure water gun flow rate is 10L / min, the polishing pad rotation speed is 70-90r / min, and the duration is 20-40s; The dressing tool rotates at a speed of 50–100 r / min, and the dressing tool pressure is 35–50 N. The dressing tool is reciprocated and scraped 3–5 times.
10. The process for chemical mechanical planarization of a recoverable wafer of claim 1 wherein, In step S11, the alkaline solution is an ammonia-containing solution with a flow rate of 300-500 ml / min, the polishing head rotation speed is 50-70 r / min, the polishing head pressure is 50 hpa-150 hpa, the polishing pad rotation speed is 50-70 r / min, and the duration is 50-70 s.
11. The process for chemical mechanical planarization of a recoverable wafer of claim 1 wherein, After performing step S11, the method further includes cleaning and drying the recyclable wafer.