Novel diffusion merging process

Abstract

The invention discloses a novel diffusion merging process, which belongs to the technical field of solar cell preparation, and comprises the following steps: S1, returning to normal pressure in a furnace tube; s2, putting the silicon wafer into a furnace tube; s3, detecting the leakage rate of the furnace tube; s4, raising the temperature in the furnace tube; s5, introducing oxygen and nitrogen into the furnace tube, and carrying out a pre-oxidation process on the silicon wafer; s6, two times of source introduction deposition are carried out, nitrogen, oxygen and a boron source are introduced into the furnace tube, and PN junctions are formed on the silicon wafer; s7, introducing nitrogen into the furnace tube, and making a deep PN junction through high-temperature junction pushing operation; s8, oxygen is continuously introduced into the furnace tube, and silicon dioxide is generated on the surface of the silicon wafer; s9, purging: introducing nitrogen into the furnace tube, and reducing the temperature in the furnace tube; s10, introducing nitrogen into the furnace tube to enable the pressure in the furnace tube to return to normal pressure; according to the novel diffusion merging technology, the oxidation step is merged into the diffusion technology, the production cost can be reduced, potential influences caused by the manufacturing process are reduced, the production period is shortened, and the yield is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cell preparation, and in particular relates to a novel diffusion merging process. Background Art

[0002] Today, the solar power generation industry has entered a stage of rapid development, and the photovoltaic industry has also ushered in a rare development opportunity, but it will also face greater challenges.

[0003] At present, the PECVD high-temperature process generally adopts the diffusion → SE → oxidation process, and a small part adopts the (LECO instead of SE) diffusion → oxidation process.

[0004] However, both processes require a diffusion process first. After the diffusion operation is completed in the diffusion process equipment, the silicon wafer needs to be moved to the oxidation process equipment. The more processes there are, the longer the overall process time will be, and the corresponding equipment maintenance cost and labor cost will also be higher, reducing product competitiveness. Summary of the invention

[0005] In order to solve the problems raised in the above background technology, the present invention provides a new diffusion merging process to solve the problem that the existing process has a large number of steps, resulting in a long overall process time, high corresponding equipment maintenance costs and labor costs, and reduced product competitiveness.

[0006] To achieve the above object, the present invention provides the following technical solutions: A novel diffusion merging process comprises the following steps: Step 1: Return the furnace tube to normal pressure; Step 2: Place the boat containing the silicon wafer into the furnace tube; Step 3: Raise the temperature in the furnace tube to 816°C-825°C; Step 4: oxygen and nitrogen are introduced into the furnace tube, the pressure in the tube is 100-300 mbar, the temperature is 810°C-850°C, and the silicon wafer is pre-oxidized; Step 5: Perform two source depositions, introduce nitrogen, oxygen and boron sources into the furnace tube, the pressure in the furnace tube is 100-300mbar, the temperature is 810℃-850℃, and the silicon wafer forms a PN junction; Step 6: Introduce nitrogen into the furnace tube and make a deep PN junction by high-temperature pushing junction operation. The pressure in the furnace tube is 100-300mbar and the temperature is 840℃-910℃; Step 7: Oxygen is continuously introduced into the furnace tube to generate silicon dioxide on the surface of the silicon wafer. The temperature inside the tube is 800°C-1100°C and the pressure inside the tube is 500-900mbar. Step 8: Purge, pass nitrogen into the furnace tube to reduce the temperature inside the furnace tube; Step 9: Introduce nitrogen into the furnace tube to return the pressure inside the furnace tube to normal pressure; Step 10: The boat is taken out of the furnace tube, completing the new diffusion merging process.

[0007] Preferably, in step 2, when the boat is placed in the furnace tube, the temperature of the furnace tube is set to 800°C-810°C.

[0008] Preferably, the novel diffusion merging process further includes step 0: detecting the leakage rate of the furnace tube, and step 0 is arranged before step 4.

[0009] Preferably, step 7 is specifically: Step 7.1: The reaction time is set to 660 s, the temperature is set to 1040°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; Step 7.2: The reaction time is set to 3600 s, the temperature is set to 1040°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; Step 7.3: The reaction time is set to 900 s, the temperature is set to 970°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; Step 7.4: The reaction time is set to 1800 s, the temperature is set to 850°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer.

[0010] Preferably, in step 8, the temperature in the furnace tube drops to 800°C.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The present application uses a diffusion merging process, that is, based on the (LECO instead of SE) diffusion → oxidation process, the oxidation process is eliminated and the oxidation step is merged into the diffusion process, which can make the production line simpler and faster, while reducing production costs and reducing the impact of potential processes. In addition, due to the reduction in process steps, the production cycle can be shortened and the output of the production line can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a flowchart of the application; Figure 2 This is a specific application diagram of this application. DETAILED DESCRIPTION

[0013] In order to facilitate those skilled in the art to understand the technical content of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0014] like Figure 1 As shown, a novel diffusion merging process comprises the following steps: S1: The furnace tube returns to normal pressure and the furnace door is opened; S2: Place the boat with silicon wafers into a furnace tube, the temperature of the furnace tube is 800℃-810℃; S3: Detect the leakage rate of furnace tube; S4: Raise the temperature in the furnace tube to 816°C-825°C; S5: oxygen and nitrogen are introduced into the furnace tube, the pressure in the tube is 100-300 mbar, the temperature is 810°C-850°C, and the silicon wafer is subjected to a pre-oxidation process; S6: performing two source depositions, introducing nitrogen, oxygen and boron sources into the furnace tube, the pressure in the furnace tube is 100-300 mbar, the temperature is 810°C-850°C, and the silicon wafer forms a PN junction; S7: nitrogen is introduced into the furnace tube, and a deep PN junction is made by high-temperature pushing operation. The pressure in the furnace tube is 100-300mbar and the temperature is 840℃-910℃; S8: Continuously introduce oxygen into the furnace tube to generate silicon dioxide on the surface of the silicon wafer. The temperature in the tube is 800℃-1100℃ and the pressure in the tube is 500-900mbar. Specifically, it includes: S8.1: The reaction time is set to 660 s, the temperature is set to 1040°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; S8.2: The reaction time is set to 3600 s, the temperature is set to 1040°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; S8.3: The reaction time is set to 900 s, the temperature is set to 970°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; S8.4: The reaction time is set to 1800 s, the temperature is set to 850°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; S9: Purge, pass nitrogen into the furnace tube to reduce the temperature inside the furnace tube to 800℃ to prevent equipment damage; S10: introducing nitrogen into the furnace tube to return the pressure inside the furnace tube to normal pressure; S11: The boat comes out of the furnace tube, completing the new diffusion merging process.

[0015] This application improves the process formula, optimizes the formula, improves the square resistance, and merges the two processes of diffusion and oxidation into one process. On the basis of the (LECO replaces SE) diffusion → oxidation process, the oxidation process is eliminated and the oxidation step is merged into the diffusion process. Figure 2 As shown, the present application adds 18-21 steps to the original process formula, uses diffused high square resistance to match LECO, improves efficiency while reducing costs, and increases the diffusion square resistance to 320-350Ω by optimizing the diffusion doping curve and square resistance. The high square resistance diffusion doping technology reduces the surface doping concentration by optimizing the deposition step and the advancement step, effectively reducing the recombination center on the surface of the cell, and increases the minority carrier survival rate on the surface of the cell while also increasing the short-wavelength light QE, thereby effectively increasing Uoc and Isc, improving efficiency by about 0.05%, and improving product competitiveness, while reducing operating costs and increasing profits.

Claims

1. A novel diffusion merging process, characterized in that: The following steps are involved: Step 1: Return the furnace tube to normal pressure; Step 2: Place the boat containing the silicon wafer into the furnace tube; Step 3: Raise the temperature in the furnace tube to 816°C-825°C; Step 4: oxygen and nitrogen are introduced into the furnace tube, the pressure in the tube is 100-300 mbar, the temperature is 810°C-850°C, and the silicon wafer is subjected to a pre-oxidation process; Step 5: Perform two source depositions, introduce nitrogen, oxygen and boron sources into the furnace tube, the pressure in the furnace tube is 100-300mbar, the temperature is 810℃-850℃, and the silicon wafer forms a PN junction; Step 6: Introduce nitrogen into the furnace tube and make a deep PN junction by high-temperature pushing junction operation. The pressure in the furnace tube is 100-300mbar and the temperature is 840℃-910℃; Step 7: Oxygen is continuously introduced into the furnace tube to generate silicon dioxide on the surface of the silicon wafer. The temperature inside the tube is 800°C-1100°C and the pressure inside the tube is 500-900mbar. Step 8: Purge, pass nitrogen into the furnace tube to reduce the temperature inside the furnace tube; Step 9: Introduce nitrogen into the furnace tube to return the pressure inside the furnace tube to normal pressure; Step 10: The boat is taken out of the furnace tube, completing the new diffusion merging process.

2. A novel diffusion merging process according to claim 1, characterized in that: In step 2, when the boat is placed in the furnace tube, the temperature of the furnace tube is set to 800°C-810°C.

3. A novel diffusion merging process according to claim 1, characterized in that: The novel diffusion merging process further includes step 0: detecting the leakage rate of the furnace tube, and step 0 is arranged before step 4.

4. A novel diffusion merging process according to claim 1, characterized in that: Step 7 is as follows: Step 7.1: The reaction time is set to 660 s, the temperature is set to 1040°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; Step 7.2: The reaction time is set to 3600s, the temperature is set to 1040°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000sccm, and the pump pressure is set to 850mbar to oxidize the silicon wafer; Step 7.3: The reaction time is set to 900 s, the temperature is set to 970°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer; Step 7.4: The reaction time is set to 1800 s, the temperature is set to 850°C, oxygen is continuously introduced into the furnace tube, the oxygen flow rate is set to 18000 sccm, and the pump pressure is set to 850 mbar to oxidize the silicon wafer.

5. A novel diffusion merging process according to claim 2, characterized in that: In step 8, the temperature in the furnace tube drops to 800°C.

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