A polishing process for removing particles from silicon wafer surface

Abstract

The present invention provides a polishing process for removing particles from the surface of a silicon wafer, wherein the polished silicon wafer is subjected to at least one rough polishing and one fine polishing. An activator is added to the rough polishing solution used for the rough polishing, and the time for adding the activator is shorter than the time for the rough polishing. The present invention provides a polishing process for removing particles from the surface of a silicon wafer, wherein an activator is added during each polishing step, and the activator addition time lasts for at least 5 seconds. This process can completely polish away particles on the surface of the silicon wafer, achieving a good polishing effect and high polishing efficiency. The process can effectively improve the cleanliness of particles on the surface of the silicon wafer, significantly improving the quality of subsequent devices, while also achieving high silicon wafer utilization and cost savings.

Description

Technical Field

[0001] The invention belongs to the technical field of cinnamon polishing, and in particular relates to a polishing process for removing particles from the surface of a silicon wafer. Background Art

[0002] Currently, the biggest challenge with chemical-mechanical polishing is the presence of numerous particles on the silicon wafer surface during the polishing process, resulting in poor surface cleanliness. Excessive particles on the wafer surface can affect subsequent device fabrication, leading to potential leakage and severely impacting product quality. Summary of the Invention

[0003] The present invention provides a polishing process for removing particles from the surface of a silicon wafer, and is particularly used to improve the cleanliness of the surface of the silicon wafer, thereby solving the technical problem that an unreasonable existing polishing process leads to a large number of particles on the surface of the silicon wafer.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A polishing process for removing particles from the surface of a silicon wafer comprises performing at least one rough polishing and one fine polishing on the polished silicon wafer; an activator is added to the rough polishing liquid used for the rough polishing, and the time for adding the activator is shorter than the time for the rough polishing.

[0006] Furthermore, the time for adding the active agent during rough polishing is not less than 5 seconds.

[0007] Furthermore, the rough polishing time is 200-300s;

[0008] The temperature of the rough polishing liquid shall not exceed 25°;

[0009] Preferably, the rough polishing liquid temperature is 20°.

[0010] Furthermore, the concentration of silicon dioxide abrasive particles in the rough polishing liquid is 18-22%, and the average particle size of silicon dioxide is 40-50 nm; and the volume ratio of the rough polishing liquid to water is 1:25.

[0011] Furthermore, the fine polishing is performed after the rough polishing and includes two fine polishings, and the active agent is added during each fine polishing, and the time for adding the active agent is shorter than the time for each fine polishing.

[0012] Furthermore, the time for adding the active agent in the two fine polishing is the same and is not less than 5 seconds.

[0013] Furthermore, the time for each fine polishing is 200-300 seconds, and the time for the two fine polishings is the same;

[0014] The temperature of the polishing liquid shall not exceed 25°;

[0015] Preferably, the polishing liquid temperature is 22°.

[0016] Furthermore, the concentration of silicon dioxide abrasive particles in the fine polishing liquid is 8.7-10%, and the average particle size of silicon dioxide is 30-38 nm; the volume ratio of the fine polishing liquid to water is 1:30.

[0017] Furthermore, the time for adding the active agent in the fine polishing is not longer than the time for adding the active agent in the rough polishing;

[0018] The activators used in rough polishing and all fine polishing are the same and are all acidic.

[0019] Furthermore, after each rough polishing and fine polishing, pure water rinsing should be carried out.

[0020] A polishing process for removing particles from the surface of a silicon wafer designed by the present invention adds an activator in each polishing step, and the activator addition time lasts for at least 5 seconds, so that particles on the surface of the silicon wafer can be completely polished away, with good polishing effect and high polishing efficiency; the cleanliness of particles on the surface of the silicon wafer can be effectively improved, which greatly improves the quality of subsequent devices, and the utilization rate of the silicon wafer is high, saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a polishing process for removing particles from the surface of a silicon wafer according to an embodiment of the present invention. 10, rough polishing 20, first fine polishing 30, second fine polishing DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] This embodiment proposes a polishing process for removing particles from the surface of a silicon wafer. Figure 1 As shown, the silicon wafer undergoes at least one rough polishing 10 and one fine polishing 20; an activator is added to the rough polishing solution used for the rough polishing 10, and the activator addition time is shorter than the rough polishing time. Because silicon wafer polishing produces numerous silicon powder particles and other impurities that adhere to the wafer surface, these silicon powder particles and impurities require polishing. During the polishing process, simply rinsing with water will not completely clean the polishing solution, let alone remove the silicon powder particles. A coarse polishing solution must first be sprayed to neutralize these surface particles and impurities. The rough polishing solution alone cannot completely polish away the silicon powder particles and impurities, so an activator must be added to enhance the polishing effect of the rough polishing solution. Rinsing with pure water can then effectively polish away the surface particles of the silicon wafer.

[0024] Furthermore, the duration of adding the activator during rough polishing (10) should be no less than 5 seconds. That is, during rough polishing (10), the duration of adding the activator for rinsing should be at least 5 seconds, or even longer, but less than the total duration of the rough polishing. 5 seconds is the minimum duration for adding the activator to neutralize the alkaline polishing solution on the wafer surface.

[0025] Furthermore, the rough polishing time is 200-300 seconds to completely remove the alkaline polishing liquid from the silicon wafer surface. During the rough polishing process, only the rough polishing liquid is used for polishing initially. After 10-50 seconds of polishing, the alkaline polishing liquid on the silicon wafer surface is softened by the rough polishing liquid. An activator is then introduced to polish particles and impurities on the silicon wafer surface together with the rough polishing liquid. The activator accelerates the separation of particles from the silicon wafer surface. After the activator is introduced for a period of time, polishing is continued in the rough polishing liquid. Preferably, the activator is added for 5 seconds to maximize the use of the activator for economic reasons.

[0026] Furthermore, the temperature of the rough polishing 10 does not exceed 25°C. At this temperature, the rough polishing solution effectively neutralizes the alkaline solution on the silicon wafer surface. Preferably, at a temperature of 20°C, the rough polishing solution and the activator achieve the best polishing effect, quickly removing particles and impurities from the silicon wafer surface and also quickly removing the alkaline polishing solution on the silicon wafer surface. In particular, this accelerates the polishing of silicon powder particles on the silicon wafer surface. In this embodiment, the alkaline polishing solution on all silicon wafer surfaces is the polishing solution added during the polishing process. Since many silicon powder particles adhere to the silicon wafer surface during polishing, the silicon wafer needs to be rinsed with pure water afterwards.

[0027] The concentration of silica abrasive particles in the rough polishing liquid is 18-22%, the average particle size of silica is 40-50 nm, and the volume ratio of the rough polishing liquid to water is 1:25.

[0028] After the rough polishing 10, the silicon wafer needs to be rinsed with pure water to clean the rough polishing liquid on the surface of the silicon wafer.

[0029] Furthermore, after the rough polishing 10, a fine polishing step is performed, which includes two fine polishing steps: a first fine polishing step 20 and a second fine polishing step 30. An activator is added during each fine polishing step, and the duration of the activator addition is shorter than the duration of each fine polishing step. The purpose of fine polishing is to remove particles and impurities on the surface of the silicon wafer using a finer-grained polishing solution to maintain the purity of the silicon wafer surface.

[0030] Furthermore, an activator is added during both the first polishing 20 and the second polishing 30, and the duration of the activator addition is the same in both polishing steps, and is no less than 5 seconds. That is, the activator is added for at least 5 seconds during both the first polishing 20 and the second polishing 30 to ensure that all silicon powder particles on the surface of the silicon wafer are completely removed. The activator is added for the same time period and duration during both polishing steps, preferably for 5 seconds.

[0031] Furthermore, each fine polishing cycle lasts 200-300 seconds, and the two fine polishing cycles last the same amount of time. Specifically, in the first fine polishing cycle 20 and the second fine polishing cycle 30, polishing is initially performed using only the fine polishing liquid. After polishing for 10-50 seconds, the fine polishing liquid softens the relatively small amount of polishing liquid remaining on the surface of the silicon wafer. An activating agent is then introduced to polish particles and impurities on the surface of the silicon wafer together with the fine polishing liquid. The activating agent accelerates the separation of particles from the silicon wafer surface, while the fine polishing liquid further polishes away impurities on the silicon wafer surface. After the activating agent has been introduced for a period of time, polishing is continued in the fine polishing liquid.

[0032] Furthermore, the temperature of the fine polishing liquid does not exceed 25°, and the temperature used in the fine polishing can be room temperature; preferably, the temperature of the fine polishing liquid is 22°, that is, the fine polishing temperature in the first fine polishing 20 and the second fine polishing 30 is the same, and both are 22°. In this process, the chemical effect of the fine polishing liquid is the best.

[0033] The polishing fluids used for both the primary polishing step 20 and the secondary polishing step 30 have the same composition and configuration. The polishing fluids contain silica abrasive particles at a concentration of 8.7-10%, with an average silica particle size of 30-38 nm. The volume ratio of the polishing fluid to water is 1:30 for all polishing steps.

[0034] Furthermore, the time for adding the activator in the first fine polishing 20 and the second fine polishing 30 is no longer than the time for adding the activator in the rough polishing 10. In this embodiment, the time for adding the activator in the rough polishing 10, the first fine polishing 20, and the second fine polishing 30 is the same, namely, 5 seconds. Furthermore, the activator used in the rough polishing 10 and all fine polishing processes is the same, and is an acidic activator such as Drynon-C.

[0035] Furthermore, after the first fine polishing 20 and the second fine polishing 30, pure water rinsing is required, that is, after the first fine polishing 20, the silicon wafer is immediately sent to the pure water cleaning tank for quick drain rinsing; after the second fine polishing 30, the silicon wafer is also immediately sent to the pure water cleaning tank for quick drain rinsing; rinsing can clean the residual cleaning liquid on the surface of the silicon wafer to ensure the purity of the silicon wafer surface.

[0036] A polishing process for removing particles from the surface of a silicon wafer designed by the present invention adds an activator in each polishing step, and the activator addition time lasts for at least 5 seconds, so that particles on the surface of the silicon wafer can be completely polished away, with good polishing effect and high polishing efficiency; the cleanliness of particles on the surface of the silicon wafer can be effectively improved, which greatly improves the quality of subsequent devices, and the utilization rate of the silicon wafer is high, saving costs.

[0037] The above embodiments of the present invention are described in detail. The contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A polishing process for removing particles from the surface of a silicon wafer, characterized in that: The steps include: Perform at least one rough polish and one fine polish on the silicon wafer; Adding an active agent to the rough polishing liquid used for rough polishing, and the time of adding the active agent is shorter than the time of rough polishing; The time of adding the active agent during rough polishing should not be less than 5s; Fine polishing is after rough polishing and includes two fine polishings. The activator is added during each fine polishing, and the time for adding the activator is less than the time for each fine polishing. The time of adding the active agent in the two fine polishing is the same and not less than 5s; The time of adding the activator in fine polishing should not be longer than that in rough polishing; Among them, the time of rough polishing is 200-300s; The temperature of the rough polishing liquid shall not exceed 25°; The concentration of silica abrasive particles in the rough polishing liquid is 18-22%, and the average particle size of silica is 40-50 nm; and the volume ratio of the rough polishing liquid to water is 1:25; Each fine polishing time is 200-300s, and the two fine polishing times are the same; The temperature of the polishing liquid shall not exceed 25°; The concentration of silica abrasive particles in the fine polishing liquid is 8.7-10%, and the average particle size of the silica is 30-38 nm; the volume ratio of the fine polishing liquid to water is 1:30; The activator used in the rough polishing and all the fine polishing is the same and is acidic, and the acidic activator is Drynon-C.

2. A polishing process for removing particles from the surface of a silicon wafer according to claim 1, characterized in that: The rough casting liquid temperature is 20°.

3. A polishing process for removing particles from the surface of a silicon wafer according to claim 1 or 2, characterized in that: The temperature of the polishing liquid is 22°.

4. A polishing process for removing particles from the surface of a silicon wafer according to claim 3, characterized in that: After each rough polishing and fine polishing, rinse with pure water.

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