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Method for diffusing high sheet resistance of solar cells

A technology of solar cells and diffusion methods, which is applied in the field of diffusion to achieve superior uniformity and high square resistance, and can solve problems such as high series resistance, poor uniformity, and difficulty in sintering high square resistance silicon wafers and positive electrode pastes, achieving The effect of increasing the minority lifetime, reducing the number of base layer faults, and superior square resistance uniformity

Active Publication Date: 2011-06-15
TRINA SOLAR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But for ordinary diffusion process, the uniformity becomes worse with the increase of square resistance, which will make the sintering of high square resistance silicon wafer and positive electrode paste more difficult, and the series resistance will be higher
[0004] High square resistance diffusion is more important in selective diffusion SE battery technology. Through selective diffusion, the field square resistance of SE battery can be made as high as 100Ω / port, which is a very important factor for ordinary diffusion process. big challenge

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] 1) Send the silicon wafer to be diffused into the diffusion furnace tube at a low temperature of 750°C.

[0020] 2) While blowing nitrogen, the temperature of the furnace tube is raised to 800°C, the temperature required for pre-deposition, where the flow rate of nitrogen is 6 liters / minute.

[0021] 3) After the temperature is stabilized, oxygen is introduced at a flow rate of 0.6 liters / minute; at the same time, TCA gas is introduced at a flow rate of 0.3 liters / minute. The growth of pre-oxidation is carried out, and the pre-oxidation time is controlled at 10 minutes, where the thickness of the oxide film is 10 nm.

[0022] 4) Turn off the TCA / TCE gas, feed POCl3, the gas flow rate is 0.8 L / min, and carry out phosphorus P diffusion, and the diffusion time is 12 minutes.

[0023] 5) Turn off the POCl3 gas and raise the temperature to 850°C. While the temperature is rising, the oxygen will react the residual POCl3, and the junction will be pushed forward at the same ti...

Embodiment 2

[0028] A P-type single crystal silicon wafer is selected, the crystal plane is (100), and the doping concentration is 0.5Ωcm. After slicing, the silicon wafers are subjected to a conventional cleaning process, and the surface is textured.

[0029] 1) Send the silicon wafer to be diffused into the diffusion furnace tube at a low temperature of 700°C.

[0030] 2) While feeding nitrogen, the temperature of the furnace tube is raised to 770°C, which is required for pre-deposition, and the flow rate of nitrogen is 15 liters / min.

[0031] 3) After the temperature is stabilized, feed oxygen with a flow rate of 1 liter / min; and simultaneously feed TCA or TCE gas with a gas flow rate of 0.5 liter / min. The growth of pre-oxidation is carried out, and the pre-oxidation time is controlled at 18 minutes, where the thickness of the oxide film is 20nm.

[0032] 4) Turn off the TCA / TCE gas, feed POCl3, the gas flow rate is 3 liters / minute, and carry out phosphorus P diffusion, and the diffus...

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Abstract

The invention relates to a method for diffusing high sheet resistance of solar cells. The method is characterized by texturing the surface of a solar crystal silicon wafer, sending the silicon wafer to a diffusion furnace for high sheet resistance diffusion and then carrying out subsequent solar cell processes. The method has the following advantages: (1) superior sheet resistance uniformity can be still maintained when high sheet resistance is diffused; (2) through introducing TCA or TCE during pre-oxidation, oxidation can be sped up, the substrate fault number can be reduced and the minority carrier lifetime of the substrate silicon can be prolonged; (3) dead layers can be well avoided through oxide layers; and (4) surface concentration and junction depth topography of diffusion can be well controlled through low-temperature pre-deposition and high-temperature junction propelling forming.

Description

technical field [0001] The invention relates to a production method of a solar cell, in particular to a diffusion method for achieving superior uniformity and high square resistance. Background technique [0002] Photovoltaic power generation is a very important field in the utilization of solar energy. It is an urgent task to seek new technologies, new materials, and new processes to improve battery conversion efficiency and reduce costs. [0003] The diffused square resistance of crystalline silicon solar cells is directly related to the performance of the battery. The existing mass-produced diffused square resistance is basically between 50 and 65 Ω / Ω. Increasing the shallow junction diffusion of the diffused square resistance can effectively improve the performance of solar cells in the short-wave band. The spectral response of the battery greatly increases the current and voltage of the battery. However, for the common diffusion process, the uniformity becomes worse wi...

Claims

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Application Information

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IPC IPC(8): H01L31/18
CPCY02P70/50
Inventor 刘亚锋
Owner TRINA SOLAR CO LTD
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