Process for improving square resistance uniformity of front boron furnace mouth by TOPcon battery

Abstract

The invention discloses a process for improving the square resistance uniformity of a front boron furnace mouth of a TOPcon battery. The process comprises the following steps: entering a furnace tube, vacuumizing, heating, keeping constant temperature, carrying out leakage detection, heating, diffusing / depositing, purging, carrying out distributed cooling 1, carrying out distributed cooling 2, breaking vacuum and taking out of a boat. Compared with the prior art, the method has the advantages that the idle running process is added, and the deposition / diffusion step is added, so that the difference between the inner paddle temperature and the furnace mouth boron source atmosphere in a short time and the environment in the process is reduced, the furnace mouth silicon wafer STD is improved, the single wafer sheet resistance uniformity is improved, the PL bad proportion is reduced, and the A-level proportion of the solar cell is increased.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a process for improving the uniformity of square resistance of a front boron furnace mouth of a TOPcon cell. Background Art

[0002] At present, the photovoltaic industry is booming worldwide, but the development of photovoltaic technology still faces two major problems: reducing costs and improving conversion efficiency. Poor PL is an important factor affecting the yield of cells. PL (Photo-Luminescence) is a method for detecting the quality of photovoltaic cells. The quality of cells is judged by observing the luminescence of cells under the stimulation of incident photons.

[0003] After the existing boron diffusion production process is completed, the long idle time of the furnace tube will lead to paddle cooling, slow re-process heating, insufficient boron source atmosphere at the furnace mouth, high furnace mouth square resistance, single-point square resistance exceeding the standard, and the first quartz boat STD (the discrete degree of square resistance of continuous test points within a single boron wafer) exceeding the control upper limit. The high STD of the cell after boron diffusion will lead to low carrier lifetime doping density of the cell, thereby increasing the proportion of half-side blackening of PL. Half-side blackening of PL is a manifestation of poor PL, which seriously affects the efficiency of photovoltaic cell storage. Summary of the invention

[0004] The purpose of the present invention is to provide a process for improving the uniformity of the square resistance of the front boron furnace mouth of a TOPcon cell. By increasing the idle running process and adding a deposition / diffusion step therein, it is ensured that the difference between the paddle temperature, the boron source atmosphere at the furnace mouth and the process environment is reduced in a short period of time, thereby improving the STD of the silicon wafer at the furnace mouth, improving the uniformity of the square resistance of the single chip, reducing the PL defect ratio, and increasing the A-level proportion of the solar cell, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: A process for improving the uniformity of square resistance of a front boron furnace mouth of a TOPcon cell comprises the following steps: Step 1: Enter the furnace tube: put the empty paddle without the quartz boat into the furnace tube, set the furnace tube temperature to 810℃±20℃, and the pressure inside the tube to 980mbar; time: 300S.

[0006] Step 2: Vacuuming: After closing the furnace door, the pressure inside the tube is set to 700 mbar and the time is 120 seconds.

[0007] Step 3, heating: raise the temperature to 820°C, set the pressure in the tube to 120 mbar, and take 540 seconds.

[0008] Step 4: Constant temperature: The temperature is set to be consistent, the pressure inside the tube is set to 95mbar, and the time is 180S.

[0009] Step 5, leak detection: the temperature and pressure are the same as before, close the gas valve and diaphragm pump, check the air tightness of the furnace tube, which is less than 2.5mbar, and it takes 60S.

[0010] Step 6, heating: the temperature is raised to 900°C, the pressure is set to 130 mbar, and the N2 is set to 3500 sccm to purge the environment inside the tube; the time is 400 seconds.

[0011] Step 7, diffusion / deposition: the temperature and pressure are the same as before, set BCL3 to 100 sccm, N2 to 2500 sccm, O2 to 540 sccm for source, and the time is 360 seconds.

[0012] Step 8, purging: set the temperature to 890°C, set BCL3 to 300 sccm to purge the BCL3 pipeline, N2 to 500 sccm, and take 180 seconds.

[0013] Step 9, distributed cooling 1: the temperature is reduced to 800°C, the pressure is increased to 600 mbar, the oxygen is set to 10000 sccm, the N2 is set to 1000 sccm to purge the pipeline, and the time is 900 s.

[0014] Step 10, distributed cooling 2: the temperature is reduced to 780°C, the pressure is increased to 600 mbar, the N2 back pressure is set to 8000 sccm and the pipeline is purged, which takes 400 seconds.

[0015] Step 11, vacuum breaking: the temperature drops to 760°C, the pressure returns to normal pressure, N2 is set to 18000sccm back pressure and the pipeline is purged, which takes 120S.

[0016] Step 12: Exit the boat: The temperature drops to 750°C, and the paddle is sent out of the furnace tube. The process is completed, which takes 400 seconds.

[0017] Beneficial effects of the present invention: The present invention increases the idle running process and adds a deposition / diffusion step therein to ensure that the difference between the paddle temperature, the furnace mouth boron source atmosphere and the process environment is reduced in a short time, thereby improving the furnace mouth silicon wafer STD, improving the single-wafer square resistance uniformity, reducing the PL defect ratio, and increasing the A-level ratio of solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0020] Example 1: Figure 1As shown, a process for improving the square resistance uniformity of the front boron furnace mouth of a TOPcon cell includes the following steps: Step 1: Enter the furnace tube: put the empty paddle without the quartz boat into the furnace tube, set the furnace tube temperature to 810℃±20℃, and the pressure inside the tube to 980mbar; time: 300S.

[0021] Step 2: Vacuuming: After closing the furnace door, the pressure inside the tube is set to 700 mbar and the time is 120 seconds.

[0022] Step 3, heating: raise the temperature to 820°C, set the pressure in the tube to 120 mbar, and take 540 seconds.

[0023] Step 4: Constant temperature: The temperature is set to be consistent, the pressure inside the tube is set to 95mbar, and the time is 180S.

[0024] Step 5, leak detection: the temperature and pressure are the same as before, close the gas valve and diaphragm pump, check the air tightness of the furnace tube, which is less than 2.5mbar, and it takes 60S.

[0025] Step 6, heating: the temperature is raised to 900°C, the pressure is set to 130 mbar, and the N2 is set to 3500 sccm to purge the environment inside the tube; the time is 400 seconds.

[0026] Step 7, diffusion / deposition: the temperature and pressure are the same as before, set BCL3 to 100 sccm, N2 to 2500 sccm, O2 to 540 sccm for source, and the time is 360 seconds.

[0027] Step 8, purging: set the temperature to 890°C, set BCL3 to 300 sccm to purge the BCL3 pipeline, N2 to 500 sccm, and take 180 seconds.

[0028] Step 9, distributed cooling 1: the temperature is reduced to 800°C, the pressure is increased to 600 mbar, the oxygen is set to 10000 sccm, the N2 is set to 1000 sccm to purge the pipeline, and the time is 900 s.

[0029] Step 10, distributed cooling 2: the temperature is reduced to 780°C, the pressure is increased to 600 mbar, the N2 back pressure is set to 8000 sccm and the pipeline is purged, which takes 400 seconds.

[0030] Step 11, vacuum breaking: the temperature drops to 760°C, the pressure returns to normal pressure, N2 is set to 18000sccm back pressure and the pipeline is purged, which takes 120S.

[0031] Step 12: Exit the boat: The temperature drops to 750°C, and the paddle is sent out of the furnace tube. The process is completed, which takes 400 seconds.

[0032] The present invention increases the idle running process and adds a deposition / diffusion step therein to ensure that the difference between the paddle temperature, the furnace mouth boron source atmosphere and the process environment is reduced in a short time, thereby improving the furnace mouth silicon wafer STD, improving the single-wafer square resistance uniformity, reducing the PL defect ratio, and increasing the A-level ratio of solar cells.

[0033] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for improving the uniformity of square resistance of the front boron furnace mouth of a TOPcon battery, characterized in that: The steps include: Step 1: Place the empty paddle without the quartz boat into the furnace tube; Step 2: Vacuuming: After closing the furnace door, the pressure inside the tube is set to 700 mbar, and the time is 120 seconds; Step 3, heating: raise the temperature to 820°C, set the pressure in the tube to 120 mbar, and take 540 seconds; Step 4, constant temperature: the temperature is set to be consistent, the pressure in the tube is set to 95mbar, and the time is 180S; Step 5, leak detection: the temperature and pressure are the same as before, close the gas valve and diaphragm pump, check the air tightness of the furnace tube, less than 2.5mbar, and it takes 60S; Step 6, heating: the temperature is raised to 900°C, the pressure is set to 130mbar, and the N2 is set to 3500sccm to purge the environment in the tube; the time is 400S; Step 7, diffusion / deposition: the temperature and pressure are the same as before, and the flow rates of BCL3, N2, and O2 are set to pass through the source, and the time is 360S; Step 8, purging: set the temperature to 890°C, set BCL3 to 300 sccm to purge the BCL3 pipeline, N2 to 500 sccm, and take 180 seconds; Step 9, distributed cooling 1: the temperature is reduced to 800°C, the pressure is increased to 600 mbar, the oxygen is set to 10000 sccm, the N2 is set to 1000 sccm to purge the pipeline, and the time is 900 s; Step 10, distributed cooling 2: the temperature is reduced to 780°C, the pressure is increased to 600 mbar, the N2 back pressure is set to 8000 sccm and the pipeline is purged, which takes 400 seconds; Step 11, vacuum breaking: the temperature drops to 760°C, the pressure returns to normal pressure, N2 is set to 18000sccm back pressure and the pipeline is purged, which takes 120S; Step 12: Exit the boat: The temperature drops to 750°C, and the paddle is sent out of the furnace tube. The process is completed, which takes 400 seconds.

2. A process for improving the uniformity of square resistance of the front boron furnace mouth of a TOPcon battery as claimed in claim 1, characterized in that: In step 1, the temperature of the furnace tube is set at 810° C.±20° C., the pressure inside the tube is set at 980 mbar, and the time is 300 seconds.

3. A process for improving the uniformity of square resistance of the front boron furnace mouth of a TOPcon battery as claimed in claim 1, characterized in that: In step 7, BCL3 is set to 100 sccm, N2 is set to 2500 sccm, and O2 is set to 540 sccm for source conduction.

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