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Method for improving phosphorus diffusion uniformity of solar cell

A solar cell, phosphorus diffusion technology, applied in circuits, electrical components, climate sustainability, etc., can solve problems such as poor repeatability and stability, differences in diffusion process parameters, and poor consistency of sheet resistance, and achieve uniform, stable and convenient gas. Process optimization, the effect of resolving inconsistencies

Active Publication Date: 2012-10-10
YANCHENG CANADIAN SOLAR INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, with this method, the boundaries between the various steps of the process are not clear, and the silicon wafers diffused at one time in a diffusion furnace are scattered in each temperature zone, resulting in a large gap in the actual diffusion process parameters of the silicon wafers in each temperature zone. Large differences lead to poor consistency, poor repeatability and stability of the sheet resistance, which in turn affects the final efficiency

Method used

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  • Method for improving phosphorus diffusion uniformity of solar cell
  • Method for improving phosphorus diffusion uniformity of solar cell

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Embodiment one: a method for improving the uniformity of solar cell phosphorus diffusion, the steps comprising:

[0029] (1) Put the silicon wafer to be processed in a diffusion furnace, the temperature of each zone in the furnace rises to 780°C, the environment in the furnace is a uniform nitrogen atmosphere, and the nitrogen flow rate is 20L / min;

[0030] (2) After the temperature is stabilized, simultaneously introduce phosphorus-carrying source gas with a flow rate of 1.8L / min, and dry oxygen with a flow rate of 2L / min, and ensure that the gas environment in the furnace is uniform and spread for 20 minutes;

[0031] (3) Stop feeding the phosphorus-carrying gas source and dry oxygen, simultaneously and uniformly increase the temperature of each zone in the furnace, at a heating rate of 4°C / min, raise the temperature to 830°C, and diffuse for 20 minutes;

[0032] (4) Cool down and leave the boat to complete the diffusion process.

Embodiment

[0034] The conventional polycrystalline P156 silicon wafers were diffused with phosphorus, and 14 pieces were taken equidistantly from the experimental slices, and the sheet resistance was measured by the five-point method. The results are as follows:

[0035] Note: unevenness = (maximum value - minimum value) / (maximum value + minimum value) × 100%

[0036] sampling

Center resistance

average

the biggest

the smallest

Unevenness

1

57.2

54.6

57.2

50.7

6.0％

2

59

56.4

59.0

54.7

3.8％

3

56

55.2

56.2

53.8

2.2％

4

55.3

54.2

55.3

52.7

2.4％

5

56.9

55.8

57.7

53.4

3.9％

6

55.1

53.9

55.2

52.9

2.1％

7

54.3

53.0

54.6

51.2

3.2％

8

55

54.4

55.0

53.0

1.8％

...

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Abstract

The invention discloses a method for improving phosphorus diffusion uniformity of a solar cell. The method comprises the following steps of: (1) placing a silicon slice in a diffusion furnace and raising the temperature of each region in the furnace to 700 to 780 DEG C, wherein the environment in the furnace is uniform nitrogen atmosphere, and the flow rate of the nitrogen gas is 8 to 30L / minute;(2) simultaneously introducing phosphorus-carrying source gas at the speed of 0.8 to 2L / minute and dry oxygen at the speed of 0.4 to 2.5L / minute after the temperature is stable, ensuring that the gas environment in the furnace is uniform, and diffusing for 10 to 40 minutes; (3) stopping introduction of the phosphorus-carrying source gas source and the dry oxygen, synchronously and uniformly raising the temperature of each region in the furnace at the rate of below 5 DEG C / minute, raising temperature to 810 to 900 DEG C and diffusing for 10 to 40 minutes; and (4) reducing temperature and taking out the silicon slice. Through uniform gas and consistent temperature in the furnace, the phosphorus diffusion uniformity during preparation of the battery plate is improved, and the conversion efficiency of the solar cell is improved to a certain extent.

Description

technical field [0001] The invention relates to a diffusion junction process for manufacturing solar cells, in particular to a method for improving the uniformity of phosphorus diffusion in solar cells. Background technique [0002] Solar cells are devices that directly convert light energy into electrical energy. Due to their cleanliness, non-pollution, inexhaustibility, and inexhaustibility, they have attracted more and more attention. [0003] Silicon solar cells are widely used at present, and their manufacturing process has also been standardized. The main steps are: chemical cleaning and surface structuring (texturing)-diffusion junction-peripheral etching-deposition of anti-reflection film-printing electrodes-sintering. Among them, diffusion junction is divided into phosphorus diffusion and boron diffusion. In the case of using P-type silicon wafers to prepare solar cells, it is necessary to perform phosphorus diffusion on the surface of silicon wafers to form an N la...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L31/18
CPCY02P70/50
Inventor 党继东黄清辛国军章灵军
Owner YANCHENG CANADIAN SOLAR INC
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