Polishing process of semiconductor-level monocrystalline silicon wafer substrate
By forming a continuous and uniform wetting film on the surface of a single crystal silicon wafer, the problems of uneven thickness and surface roughness in the polishing process of single crystal silicon wafer are solved, and the processing quality and efficiency are improved.
Patent Information
- Application Number
- CN202510676324.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-24
- Publication Date
- 2025-08-29
AI Technical Summary
In the polishing process of single crystal silicon wafer substrates, especially large-size and thin-thick single crystal silicon wafer substrates, problems such as uneven thickness, rough and uneven surfaces and fragmentation are prone to occur, which affects processing quality and efficiency.
The single crystal silicon wafer is soaked by using alcohol amines, silicone long-chain quaternary ammonium salts, wetting agents, film forming agents and water to form a continuous and uniform wetting film, improving the thermal stress and corrosion problems during the subsequent polishing process, and then polishing is used with silicon oxide polishing liquid.
The thickness uniformity and surface flatness of the single crystal silicon wafer substrate are significantly improved, the risk of fragmentation is reduced, and the processing quality and efficiency are improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor wafer processing, and more specifically, to a polishing process for semiconductor-grade single-crystal silicon wafer substrates. Background Art
[0002] Industrial demand for silicon primarily comes from two sources: semiconductor-grade and photovoltaic-grade. Semiconductor-grade and photovoltaic-grade monocrystalline silicon differ in their processing processes. Semiconductor wafer substrates are typically made of high-purity monocrystalline silicon. Monocrystalline silicon, a single crystal composed of extremely pure silicon atoms, possesses excellent semiconductor properties and is widely used in chip manufacturing and solar cells.
[0003] At present, the polishing process is a crucial step in the processing of single-crystal silicon wafer substrates. The polishing process is mainly a chemical mechanical polishing process using silicon oxide polishing liquid and non-woven polishing pads.
[0004] To ensure the flatness of single-crystal silicon wafer substrates during processing, silicon dioxide in silicon oxide polishing liquid is usually dispersed in the polishing liquid in a spherical or quasi-spherical shape. As polishing proceeds, the processing temperature and chemical corrosiveness increase, and thermal stress intensifies. The polishing liquid is affected by the polishing environment. Although it can maintain a certain polishing performance, it will have the problem of local uneven roughness. Especially for some single-crystal silicon wafer substrates with larger substrate size and thinner substrate thickness, problems such as uneven thickness, rough and uneven surface, and broken pieces are prone to occur, seriously affecting the processing quality and processing efficiency of the single-crystal silicon wafer substrate. Summary of the Invention
[0005] In order to solve the problem that large-sized, thin-thick single-crystal silicon wafer substrates are prone to uneven thickness and rough and uneven surface during the continuous polishing process, the present application provides a polishing process for semiconductor-grade single-crystal silicon wafer substrates.
[0006] The present application provides a polishing process for semiconductor-grade single-crystal silicon wafer substrates, which adopts the following technical solutions: A polishing process for a semiconductor-grade single-crystal silicon wafer substrate comprises the following steps: S1. Soaking the ground single crystal silicon wafer in a pretreatment agent to obtain a pretreated single crystal silicon wafer; S2. Polishing and cleaning the pretreated single crystal silicon wafer obtained in step S1 using a silicon oxide polishing solution to obtain a single crystal silicon wafer substrate; The pretreatment agent in step S1 is prepared from an alcoholamine substance, an organosilicon long-chain quaternary ammonium salt, a wetting agent, a film-forming agent and water.
[0007] By adopting the above technical solution, the ground single crystal silicon wafer is first soaked in a pretreatment agent made from an alcohol amine substance, a long-chain quaternary ammonium salt of organic silicon, a wetting agent, a film-forming agent and water. The pretreatment agent can form a continuous and uniform wetting film on the surface of the single crystal silicon wafer, which can continuously improve the contact area between the silicon oxide polishing liquid and the single crystal silicon wafer during the subsequent polishing process, improve the thermal stress and corrosion problems during the polishing process, and thus improve the continuous polishing uniformity; then, the silicon oxide polishing liquid is used for polishing, effectively improving the processing quality and processing efficiency of the single crystal silicon wafer substrate. This method is particularly suitable for semiconductor-grade single crystal silicon wafer substrates with large size and thin substrate thickness, and can significantly improve problems such as uneven thickness, rough surface and fragmentation. It is suitable for polishing with silicon oxide polishing liquids of different particle sizes and system abrasives, thereby improving the thickness uniformity and surface flatness uniformity of the obtained single crystal silicon wafer substrate.
[0008] Preferably, the pretreatment agent is prepared from the following raw materials in parts by weight: Alcoholamines 6-10% Silicone long-chain quaternary ammonium salt 2-4% Wetting agent 4-8% Film former 2-5% Water balance.
[0009] By adopting the above technical solution, the dosage of each component is further optimized. The amine substances have good hydrophilicity and can improve the penetration performance of the pretreatment agent on the surface of the single crystal silicon wafer. The silicone long-chain quaternary ammonium salt, the wetting agent and the film-forming agent have a good synergistic effect, which can enhance the adsorption capacity of the pretreatment agent on the surface of the single crystal silicon wafer, so that the pretreatment agent is evenly dispersed and spread on the wafer surface, thereby forming a uniformly flat continuous film, reducing the uneven thickness problem in the subsequent polishing process, thereby improving the thickness uniformity and surface flatness of the final single crystal silicon wafer substrate.
[0010] Preferably, the pretreatment agent is prepared by the following steps: adding an alcoholamine substance and an organosilicon long-chain quaternary ammonium salt into water, dispersing them evenly, adding a wetting agent and a film-forming agent, and stirring them evenly to prepare the pretreatment agent.
[0011] By adopting the above technical solution, the stirring and dispersing process has the advantages of being simple and easy to operate, and the prepared pretreatment agent system is dispersed evenly and stably.
[0012] Preferably, the alcoholamine substance is isopropanolamine and / or diethanol monoisopropanolamine.
[0013] By adopting the above technical solution and using isopropanolamine and / or diethanol monoisopropanolamine as the alcoholamine substance, the wetting performance of the pretreatment agent can be effectively improved, and the uniform distribution of chemical mechanical action in the subsequent polishing process can be promoted, thereby improving the flatness of the surface of the single crystal silicon wafer substrate.
[0014] Preferably, the organosilicon long-chain quaternary ammonium salt is octadecyldimethyltrimethylsilylpropylammonium chloride.
[0015] By adopting the above technical solution, octadecyldimethyltrimethylsilylpropylammonium chloride is used as a long-chain quaternary ammonium salt of organic silicon, which has excellent adsorption performance and antistatic ability. It can form a uniform and stable protective layer during the pretreatment process, thereby increasing the continuous contact area between the single crystal silicon wafer substrate and the silicon oxide polishing liquid in the subsequent polishing process, thereby improving the thickness uniformity and surface flatness of the obtained single crystal silicon wafer substrate.
[0016] Preferably, the wetting agent consists of hydroxyethyl chitosan and oleamidopropyl dimethyl tertiary amine in a weight ratio of 1:(2-4).
[0017] By adopting the above technical solution, hydroxyethyl chitosan and oleamide propyl dimethyl tertiary amine in a relatively optimal weight ratio are used as wetting agents, so that the prepared pretreatment agent can be more easily and evenly covered on the surface of the single crystal silicon wafer, thereby improving the distribution state of the silicon oxide polishing liquid in the subsequent polishing process, thereby effectively reducing the local roughness problem caused by uneven distribution of the silicon oxide polishing liquid.
[0018] Preferably, the film-forming agent is composed of palm wax emulsion and hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer in a weight ratio of (1.5-2.5):1.
[0019] By adopting the above technical solution, using a palm wax emulsion and hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer with an optimal weight ratio as film-forming agents, a uniform and stable protective film can be formed on the surface of the single-crystal silicon wafer, which helps to reduce surface damage caused by thermal stress or corrosion during the polishing process, improve the thickness uniformity and surface flatness of the single-crystal silicon wafer substrate, and thus improve the overall processing quality of semiconductor-grade single-crystal silicon wafer substrates.
[0020] Preferably, the soaking temperature in step S1 is 40-50° C., and the soaking time is 10-20 min.
[0021] By adopting the above technical solution, the optimal soaking temperature and time can enable the pretreatment agent to fully soak the single crystal silicon wafer and form a continuous and uniform wetting film on the surface of the single crystal silicon wafer.
[0022] Preferably, the particle size of the silicon oxide in the silicon oxide polishing liquid in step S2 is 40-150 nm.
[0023] By adopting the above-mentioned technical solution, the preparation process of the present application is combined with a pretreatment agent to polish single-crystal silicon wafers, and is suitable for polishing silicon oxide polishing liquid with a wide particle size range of 40-150nm. The selectivity of the silicon oxide polishing liquid in the subsequent polishing process is relatively wide and the applicability is strong. It can significantly improve the surface flatness and thickness uniformity of the obtained single-crystal silicon wafer substrate, while reducing the risk of fragmentation and improving the overall processing quality and efficiency.
[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. The present application discloses a polishing process for semiconductor-grade single-crystal silicon wafer substrates, which involves first immersing the single-crystal silicon wafer in a pretreatment agent and then polishing it. The pretreatment agent, which is made of an alcohol amine substance, a long-chain quaternary ammonium salt of organic silicon, a wetting agent, a film-forming agent, and water, can form a protective thin film on the surface of the single-crystal silicon wafer. This not only continuously improves the contact area between the silicon oxide polishing liquid and the single-crystal silicon wafer during the subsequent polishing process, but also enhances the thermal stress and chemical corrosion resistance of the single-crystal silicon wafer surface. The process is suitable for semiconductor-grade single-crystal silicon wafer substrates with a larger size and a thinner substrate thickness, and can significantly improve problems such as uneven thickness, rough and uneven surface, and fragmentation.
[0025] 2. The wetting agent composed of hydroxyethyl chitosan and oleamidopropyl dimethyl tertiary amine, and the film-forming agent composed of palm wax emulsion and hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer show excellent synergistic effect with the long-chain quaternary ammonium salt of silicone. They can enhance the adsorption capacity of the pretreatment agent on the surface of the single crystal silicon wafer, so that the pretreatment agent is evenly dispersed and spread on the wafer surface, thereby forming a uniform and continuous thin film, reducing the uneven thickness problem in the subsequent polishing process, thereby improving the thickness uniformity and surface flatness of the final single crystal silicon wafer substrate.
[0026] 3. The preparation process of the present application is used in conjunction with a pretreatment agent to polish single crystal silicon wafers, and is suitable for polishing silicon oxide polishing liquid with a wide particle size range of 40-150nm. The selectivity of the silicon oxide polishing liquid in the subsequent polishing process is relatively broad and the applicability is strong. DETAILED DESCRIPTION
[0027] The present application is further described in detail below with reference to the embodiments.
[0028] The following are the sources and specifications of some raw materials of this application. The raw materials used in the preparation examples and examples of this application can be obtained from commercial sources, including but not limited to the following models and manufacturers. Raw materials with equivalent performance can be used: 1. Octadecyldimethyltrimethylsilylpropylammonium chloride: CAS No. 27668-52-6, content 40-42wt%; 2. Hydroxyethyl chitosan: CAS No. 123938-86-3, deacetylation degree 85%; 3. Oleamidopropyl dimethyl tertiary amine: CAS No. 109-28-4, content 99%; 4. Palm wax emulsion: Carnauba wax emulsion, model CE-325; 5. Hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer: France Seppic, model EMT-10; 6. Silicon oxide polishing liquid: Wuxi Jizhi Electronics, silicon oxide polishing liquid.
[0029] Preparation example of pretreatment agent Preparation Example 1 Preparation Example 1 discloses a pretreatment agent, which is prepared by the following steps: 0.6 kg of monoethanolamine as an alcoholamine substance and 0.2 kg of octadecyldimethyltrimethylsilyl ammonium chloride as an organosilicon long-chain quaternary ammonium salt were added to 8.2 kg of water, and after uniform dispersion, 0.8 kg of a wetting agent (composed of sodium dodecylbenzenesulfonate and hydroxyethyl chitosan in a weight ratio of 2:1) and 0.2 kg of polyvinyl alcohol as a film-forming agent were added and stirred evenly to prepare a pretreatment agent; the polyvinyl alcohol was PVA2488.
[0030] Preparation Example 2-3 The difference between Preparation Example 2-3 and Preparation Example 1 is that the amount of raw materials used and the preparation conditions are different. Please refer to Table 1 below for details.
[0031] Table 1 Parameters of Preparation Examples 1-3 Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that an equal amount of monoethanolamine is replaced by isopropanolamine, and the other ingredients are the same as Preparation Example 1.
[0032] Preparation Example 5 The difference between Preparation Example 5 and Preparation Example 1 is that an equal amount of monoethanolamine is replaced by diethanol monoisopropanolamine, and the other ingredients are the same as Preparation Example 1.
[0033] Preparation Example 6 The difference between Preparation Example 6 and Preparation Example 5 is that the wetting agent consists of hydroxyethyl chitosan and oleamidopropyl dimethyl tertiary amine in a weight ratio of 1:2, and the rest is the same as Preparation Example 5.
[0034] Preparation Example 7 The difference between Preparation Example 7 and Preparation Example 5 is that the wetting agent consists of hydroxyethyl chitosan and oleamidopropyl dimethyl tertiary amine in a weight ratio of 1:4, and the rest is the same as Preparation Example 5.
[0035] Preparation Example 8 The difference between Preparation Example 8 and Preparation Example 6 is that the film-forming agent consists of palm wax emulsion and hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer in a weight ratio of 1.5:1, and the rest is the same as Preparation Example 6.
[0036] Preparation Example 9 The difference between Preparation Example 9 and Preparation Example 6 is that the film-forming agent consists of palm wax emulsion and hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer in a weight ratio of 2.5:1, and the rest is the same as Preparation Example 6.
[0037] Preparation Comparative Example 1 The difference between Preparation Comparative Example 1 and Preparation Example 1 is that an equal amount of the organosilicon long-chain quaternary ammonium salt is replaced by polyquaternium-7, and the rest is the same as Preparation Example 1.
[0038] Preparation Comparative Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that an equal amount of the alcohol amine substance is replaced by the wetting agent, and the rest is the same as Preparation Example 1.
[0039] Preparation Comparative Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that the film-forming agent is replaced by an equal amount of organosilicon long-chain quaternary ammonium salt, and the rest is the same as Preparation Example 1. Example
[0040] Example 1 Example 1 discloses a polishing process for a semiconductor-grade single crystal silicon wafer substrate, comprising the following steps: S1. Soaking a ground single crystal silicon wafer having a diameter of 200 mm and a thickness of 725 μm in the pretreatment agent prepared in Preparation Example 1 at a temperature of 40° C. for 20 minutes to obtain a pretreated single crystal silicon wafer. S2. The pretreated single crystal silicon wafer obtained in step S1 was polished using a polishing machine. A silicon oxide polishing liquid with a particle size of 40 nm and a concentration of 10 wt % was used. The polishing liquid flow rate was controlled at 3 L / min. The polishing machine parameters were adjusted as follows: the polishing disc speed was 40 rpm, the polishing turntable speed was 40 rpm, and the polishing pressure was 200 g / cm 2 , place a non-woven polishing pad on the polishing turntable (non-woven polishing pad parameters: hardness 75A, density 0.43g / cm 3 , compression elasticity 69%), polished for 10 minutes, and then cleaned to obtain a single crystal silicon wafer substrate.
[0041] Example 2-3 The difference between Example 2-3 and Example 1 is that the process parameters are different, see Table 2 below for details.
[0042] Table 2 Parameters of Examples 1-3 Examples 4-9 The difference between Examples 4-9 and Example 1 is that the sources of the pretreatment agents are different, see Table 3 below for details.
[0043] Table 3 Sources of pretreatment agents for Examples 4-9 Example Source of pretreatment agent Example 4 Preparation Example 4 Example 5 Preparation Example 5 Example 6 Preparation Example 6 Example 7 Preparation Example 7 Example 8 Preparation Example 8 Example 9 Preparation Example 9 Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the pretreatment agent is derived from the preparation of Comparative Example 1, and the rest is the same as Example 1.
[0044] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the pretreatment agent is derived from the preparation of Comparative Example 2, and the rest is the same as Example 1.
[0045] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the pretreatment agent is derived from the preparation of Comparative Example 3, and the rest is the same as Example 1.
[0046] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the ground single crystal silicon wafer is not immersed, but is directly polished, and the rest is the same as Example 1.
[0047] Performance testing The following performance tests were conducted on the semiconductor-grade single crystal silicon wafer substrates prepared in Examples 1-9 and Comparative Examples 1-4: 1. Thickness uniformity test Use a wafer thickness gauge to measure the thickness at the center and four edge positions of the single crystal silicon wafer substrate according to the 5-point measurement method. Calculate the standard deviation of the thickness at the five points. The smaller the standard deviation, the better the thickness uniformity. Test and record the test results. 2. Surface flatness test Use a non-contact step profiler to test the surface roughness (Ra, nm) of the single crystal silicon wafer substrate, and test and record the test results; the following is the performance test data of the semiconductor-grade single crystal silicon wafer substrates prepared in Examples 1-9 and Comparative Examples 1-4, see Table 4 below for details.
[0048] Table 4 Performance test data of Examples 1-9 and Comparative Examples 1-4 Combining Examples 1-3 and Comparative Example 4 and Table 4, it can be concluded that the use of the process of pre-treatment followed by polishing of the present application can improve the thickness uniformity and surface flatness of the obtained single crystal silicon wafer substrate. Compared with Example 1, the roughness of Comparative Example 4 is increased by 0.54 nm and the thickness uniformity is reduced by 1.91 μm.
[0049] Combining Examples 1-3 and Examples 4-9, Comparative Examples 1-3 and Table 4, it can be measured that by optimizing the type of alcoholamine substances in Examples 4-5, the thickness uniformity and surface smoothness of the obtained single crystal silicon wafer substrate are improved; by further optimizing the type and ratio of the wetting agent in Examples 6-7, and by further optimizing the type and ratio of the film-forming agent in Examples 8-9, the thickness uniformity and surface smoothness of the obtained single crystal silicon wafer substrate are improved; and in Comparative Example 1, the organosilicon long-chain quaternary ammonium salt is replaced by a polyquaternary ammonium salt -7, in Comparative Example 2, no amine substance was added, but a wetting agent was used instead; in Comparative Example 3, no film-forming agent was added, but a long-chain quaternary ammonium salt of silicone was used instead. The thickness uniformity and surface smoothness of the obtained single-crystal silicon wafer substrate were significantly reduced, indicating that the amine substance, long-chain quaternary ammonium salt of silicone, wetting agent and film-forming agent of the present application have a good synergistic effect, and the compound can significantly improve the thickness uniformity and surface smoothness of the obtained single-crystal silicon wafer substrate, and is particularly suitable for the polishing process of large-size, thin-thickness single-crystal silicon wafers.
[0050] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.
Claims
1. A polishing process for semiconductor-grade single-crystal silicon wafer substrates, characterized in that: The following steps are involved: S1. Soaking the ground single crystal silicon wafer in a pretreatment agent to obtain a pretreated single crystal silicon wafer; S2. Polishing and cleaning the pretreated single crystal silicon wafer obtained in step S1 using a silicon oxide polishing solution to obtain a single crystal silicon wafer substrate; The pretreatment agent in step S1 is prepared from an alcoholamine substance, an organosilicon long-chain quaternary ammonium salt, a wetting agent, a film-forming agent and water.
2. The polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 1, characterized in that: The pretreatment agent is prepared from the following raw materials in parts by weight: Alcoholamines 6-10% Silicone long-chain quaternary ammonium salt 2-4% Wetting agent 4-8% Film former 2-5% Water balance.
3. A polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 1 or 2, characterized in that: The pretreatment agent is prepared by the following steps: adding alcoholamine substances and organosilicon long-chain quaternary ammonium salt into water, dispersing them evenly, adding a wetting agent and a film-forming agent, and stirring them evenly to prepare the pretreatment agent.
4. The polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 3, characterized in that: The alcoholamine substance is isopropanolamine and / or diethanol monoisopropanolamine.
5. The polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 3, characterized in that: The organosilicon long-chain quaternary ammonium salt is octadecyldimethyltrimethylsilylpropylammonium chloride.
6. The polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 3, characterized in that: The wetting agent consists of hydroxyethyl chitosan and oleamidopropyl dimethyl tertiary amine in a weight ratio of 1:(2-4).
7. The polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 3, characterized in that: The film-forming agent consists of a palm wax emulsion and a hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer in a weight ratio of (1.5-2.5):
1.
8. The polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 1, characterized in that: The soaking temperature in step S1 is 40-50° C., and the soaking time is 10-20 minutes.
9. The polishing process for a semiconductor-grade single crystal silicon wafer substrate according to claim 1, characterized in that: The particle size of the silicon oxide in the silicon oxide polishing liquid in step S2 is 40-150 nm.