Process method for improving appearance yield of APCVD silicon wafer

Abstract

The invention relates to a process method for improving the appearance yield of an APCVD silicon wafer, which belongs to the technical field of silicon wafer processing, and comprises the following operation steps: 1, in the processing process of grinding off SiO2 on a chamfering surface by using an adhesive tape with SiC particles and a mechanical method, fixing a grinding table, adjusting the water flow rate to be 0.3 L / min, adjusting the direction of water flow to be consistent, and spraying the water flow to a fixed position of a positioning notch; 2, pasting a protective adhesive tape on the back surface of the silicon wafer; and 3, corroding off silicon dioxide on the chamfered surface by using hydrofluoric acid HF. And 4, stripping the protective adhesive tape. Therefore, the back surface damage and the front surface pit defect of the silicon wafer are obviously improved, and the appearance yield of APCVD processing is improved. And the appearance yield is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon wafer processing, and in particular to a process method for improving the appearance yield of APCVD silicon wafers. Background Art

[0002] Chemical vapor deposition (CVD) is a technology that introduces gaseous raw materials into a reaction chamber, allowing them to react chemically with each other to form a new material that is deposited on the surface of the substrate. Common CVD processing methods are divided into low-pressure chemical vapor deposition (LPCVD) and atmospheric pressure chemical vapor deposition (APCVD).

[0003] APCVD refers to the process of growing a layer of SiO2 film (back seal) on the back of a silicon wafer under normal pressure. This process can effectively prevent the dopant in the silicon wafer from diffusing out from the back during the subsequent epitaxial processing, forming a self-doping effect, thereby preventing the resistivity uniformity of the epitaxial layer from deteriorating.

[0004] After APCVD, a layer of silicon dioxide is also accumulated on the chamfered surface. The end surface treatment is mainly a process of removing the SiO2 film deposited on the end surface and notch of the silicon wafer after CVD processing by physical or chemical methods. During the end surface treatment process, silicon wafers often produce appearance defects such as back scratches, pits and scratches on the polished surface. This is especially true for silicon wafers that undergo (1) BSD (2) APCVD (3) end surface treatment processes. Summary of the invention

[0005] The present invention mainly solves the deficiencies in the prior art and provides a process method for improving the appearance yield of APCVD silicon wafers, which significantly improves the back surface scratches and front surface pit defects of silicon wafers and improves the appearance yield of APCVD processing. The appearance yield has been significantly improved.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions: A process for improving the appearance yield of APCVD silicon wafers, comprising the following steps: Step 1: When using a tape with SiC particles to mechanically grind away SiO2 from the chamfered surface, fix the grinding table position, set the water flow rate to 0.3L / min, and adjust the water flow direction to spray to the fixed position of the positioning notch.

[0007] Step 2: Apply protective tape to the back of the silicon wafer.

[0008] Step 3: Use hydrofluoric acid HF to etch away the silicon dioxide on the chamfered surface.

[0009] Step 4: Peel off the protective tape.

[0010] Preferably, when cleaning the grinding table regularly, first use a nitrogen gun to purge the grinding table, then use a water spray gun to rinse the grinding table, and finally use a nitrogen gun to purge the grinding table. After cleaning, observe whether there is any foreign matter on the surface of the grinding table.

[0011] Preferably, during the tape application process, the application pressure is set to 0.35Mpa to ensure that the tape application does not generate bubbles. At the same time, Teflon tape is applied to the application tray to prevent the presence of particles on the tray surface during the application process, which may cause excessive pressure on the silicon wafer by the roller and cause pits on the front side.

[0012] Preferably, during the HF etching process, the 49% HF cleaning time of the first tank 16L is 360s, the pure water overflow of the second tank is 300s, and the overflow flow rate is 15±5 L / min.

[0013] Preferably, the wet silicon wafer is spun dry in a spun dryer at a rotation speed of 600 r / min for 180 s.

[0014] Preferably, when the tape is peeled off, the pressure of the peeling tape is 0.35 MPa and the temperature of the peeling table is 65°C.

[0015] Preferably, the peeling roller is wrapped with a layer of Teflon tape to reduce the probability of back surface damage to the silicon wafer film surface during the peeling process.

[0016] The present invention can achieve the following effects: The present invention provides a process method for improving the appearance yield of APCVD silicon wafers. Compared with the prior art, the back surface scratches and front surface pit defects of silicon wafers are significantly improved, and the appearance yield of APCVD processing is improved. The appearance yield is significantly improved. DETAILED DESCRIPTION

[0017] The technical solution of the invention is further specifically described below through embodiments.

[0018] Embodiment: A process for improving the appearance yield of APCVD silicon wafers, comprising the following steps: Step 1: When using the tape with SiC particles to mechanically grind the chamfered surface SiO2, fix the grinding table, set the water flow rate to 0.3L / min, and adjust the water flow direction to spray to the fixed position of the positioning notch. Ensure that there are no large particles left on the silicon wafer film surface after the positioning notch is ground to prevent back damage during the grinding process.

[0019] When cleaning the grinding table regularly, first use a nitrogen gun to purge the grinding table, then use a water spray gun to rinse the grinding table, and finally use a nitrogen gun to purge the grinding table. After cleaning, observe whether there is any foreign matter on the surface of the grinding table.

[0020] Step 2: Apply protective tape to the back of the silicon wafer.

[0021] During the tape application process, the application pressure is set to 0.35Mpa to ensure that no bubbles are generated during the tape application. At the same time, Teflon tape is applied to the application tray to prevent the presence of particles on the tray surface during the application process, which may cause excessive pressure on the silicon wafer by the roller and cause pits on the front side.

[0022] Step 3: Use hydrofluoric acid HF to etch away the silicon dioxide on the chamfered surface.

[0023] During the HF etching process, the first tank 16L of 49% HF cleaning time is 360s, the second tank pure water overflows for 300s, and the overflow flow rate is 15±5 L / min. The wet silicon wafer is dried in a spin dryer with a rotation speed of 600r / min for 180s.

[0024] Step 4: Peel off the protective tape. When peeling off the tape, the pressure of the peeling tape is 0.35Mpa and the temperature of the peeling table is 65℃. The peeling roller is wrapped with a layer of Teflon tape to reduce the probability of back damage to the silicon wafer film surface during the peeling process.

[0025] In summary, the process method for improving the appearance yield of APCVD silicon wafers has significantly improved the backside scratches and front side pit defects of silicon wafers, and improved the appearance yield of APCVD processing. The appearance yield has been significantly improved.

[0026] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A process for improving the appearance yield of APCVD silicon wafers, characterized in that The steps are as follows: Step 1: When using a tape with SiC particles to mechanically grind away the SiO2 on the chamfered surface, fix the grinding table position, set the water flow rate to 0.3L / min, and adjust the water flow direction to spray to the fixed position of the positioning notch; Step 2: Apply protective tape to the back of the silicon wafer; Step 3: Use hydrofluoric acid HF to etch away the silicon dioxide on the chamfered surface; Step 4: Peel off the protective tape.

2. The process for improving the appearance yield of APCVD silicon wafers according to claim 1, characterized in that: When cleaning the grinding table regularly, first use a nitrogen gun to purge the grinding table, then use a water spray gun to rinse the grinding table, and finally use a nitrogen gun to purge the grinding table. After cleaning, observe whether there is any foreign matter on the surface of the grinding table.

3. The process for improving the appearance yield of APCVD silicon wafers according to claim 1, characterized in that: During the tape application process, the application pressure is set to 0.35Mpa to ensure that no bubbles are generated during the tape application. At the same time, Teflon tape is applied to the application tray to prevent the presence of particles on the tray surface during the application process, which may cause excessive pressure on the silicon wafer by the roller and cause pits on the front side.

4. The process for improving the appearance yield of APCVD silicon wafers according to claim 1, characterized in that: During the HF etching process, the 49% HF cleaning time of the first tank 16L is 360s, the pure water overflow in the second tank is 300s, and the overflow flow rate is 15±5 L / min.

5. The process for improving the appearance yield of APCVD silicon wafers according to claim 4, characterized in that: The wet silicon wafer was dried in a spin dryer at a rotation speed of 600 r / min for 180 s.

6. The process for improving the appearance yield of APCVD silicon wafers according to claim 1, characterized in that: When the tape is peeled off, the pressure of the tape is 0.35 MPa and the temperature of the peeling table is 65°C.

7. The process for improving the appearance yield of APCVD silicon wafers according to claim 6, characterized in that: The peeling roller is wrapped with a layer of Teflon tape to reduce the chance of back surface damage to the silicon wafer film surface during the peeling process.