A boron process suitable for p+ selective emitter cells

Abstract

The invention relates to a boron process suitable for P+ selective emitter batteries, comprising the following steps: (1) constant source boron spin-coating; (2) drying; (3) feeding into a furnace tube; (4) leak detection (5) heating oxidation; (6) anaerobic propulsion; (7) high temperature oxidation; (8) cooling; (9) low temperature product boron source; (10) low temperature propulsion; miscellaneous. The present invention, through the combined effect of constant boron source and gas boron source doping, forms a lightly doped region on the one hand, has a shallow junction structure with a higher surface concentration, and can effectively increase the open circuit voltage and short circuit current of the battery; on the other hand On the one hand, laser is used for secondary doping to form a heavily doped region, which can effectively improve the ohmic contact and increase the fill factor.

Description

technical field

[0001] The invention relates to the field of solar cell manufacturing, in particular to a boron process suitable for P+ selective emitter cells. Background technique

[0002] As the demand for affordable Internet access intensifies, high-efficiency batteries have become a development trend. Especially today's N-TOPCon batteries are getting more and more popular. However, how to raise the efficiency of N-TOPCon batteries to a higher level has become the focus of research and development. Among them, boron diffusion is widely used in N-type high-efficiency solar cells as an important means of p+ layer doping. The common method is to carry gas boron source into the furnace tube for single boron doping, but for boron selective doping diffusion technology is still blank.

[0003] Moreover, the conventional boron diffusion process is required to form a good ohmic contact with the metal electrode, and the square resistance is low, which leads to high recombinatio...

Examples

Embodiment 1

[0048] A constant source boron diffusion process suitable for P+ selective emitter batteries, the specific process is as follows: use N-type silicon wafers with high minority carrier life, resistivity 0.2-2Ω.cm, double-sided alkali washing for texture;

[0049] (1) Constant source boron spin-coating—use 1-1.5mL of immersion solution to spin on the silicon wafer, and then drop 0.4-0.8ml of boron source to spin on the silicon wafer. The spin coating method can produce a higher square resistance of 120-140ohm, and the uniformity STD<8;

[0050] (2) Drying—on a chain machine at a temperature of 120-200°C and a drying time of 30-60s;

[0051] (3) Entering the boat - the temperature is maintained at 750-850°C, the nitrogen flow rate is 1000-2000sccm, and the time is about 8-15min;

[0052] (4) Leak detection - the flow rate of nitrogen gas is 1000-1500sccm, and the pressure is controlled at 100-200pa;

[0053] (5) Heating Oxidation—The temperature rises to 900-960°C, the nitrogen ...

Embodiment 2

[0063] A constant source boron diffusion process suitable for P+ selective emitter batteries, the specific process is as follows: use N-type silicon wafers with high minority carrier life, resistivity 2-6Ω.cm, double-sided alkali-washed texture;

[0064] (1) Constant source boron spin-coating—use 1.5-2.5mL of immersion solution to spin on the silicon wafer by spin-coating, and then drop 0.3-0.6ml of boron source to spin on the silicon wafer. The spin coating method can produce a higher square resistance of 130-200ohm, and the uniformity STD: 9-10;

[0065] (2) Drying—on a chain machine at a temperature of 180-250°C and a drying time of 40-80s;

[0066] (3) Entering the boat - the temperature is maintained at 750-850°C, the nitrogen flow rate is 1500-2500sccm, and the time is about 6-15min;

[0067] (4) Leak detection - the nitrogen flow rate is 1500-2500sccm, and the pressure is controlled at 100-200pa;

[0068] (5) Heating Oxidation—The temperature rises to 950-1000°C, the ...

technical field

[0001] The invention relates to the field of solar cell manufacturing, in particular to a boron process suitable for P+ selective emitter cells. Background technique

[0002] As the demand for affordable Internet access intensifies, high-efficiency batteries have become a development trend. Especially today's N-TOPCon batteries are getting more and more popular. However, how to raise the efficiency of N-TOPCon batteries to a higher level has become the focus of research and development. Among them, boron diffusion is widely used in N-type high-efficiency solar cells as an important means of p+ layer doping. The common method is to carry gas boron source into the furnace tube for single boron doping, but for boron selective doping diffusion technology is still blank.

[0003] Moreover, the conventional boron diffusion process is required to form a good ohmic contact with the metal electrode, and the square resistance is low, which leads to high recombinatio...

Examples

Embodiment 1

[0048] A constant source boron diffusion process suitable for P+ selective emitter batteries, the specific process is as follows: use N-type silicon wafers with high minority carrier life, resistivity 0.2-2Ω.cm, double-sided alkali washing for texture;

[0049] (1) Constant source boron spin-coating—use 1-1.5mL of immersion solution to spin on the silicon wafer, and then drop 0.4-0.8ml of boron source to spin on the silicon wafer. The spin coating method can produce a higher square resistance of 120-140ohm, and the uniformity STD<8;

[0050] (2) Drying—on a chain machine at a temperature of 120-200°C and a drying time of 30-60s;

[0051] (3) Entering the boat - the temperature is maintained at 750-850°C, the nitrogen flow rate is 1000-2000sccm, and the time is about 8-15min;

[0052] (4) Leak detection - the flow rate of nitrogen gas is 1000-1500sccm, and the pressure is controlled at 100-200pa;

[0053] (5) Heating Oxidation—The temperature rises to 900-960°C, the nitrogen ...

Embodiment 2

[0063] A constant source boron diffusion process suitable for P+ selective emitter batteries, the specific process is as follows: use N-type silicon wafers with high minority carrier life, resistivity 2-6Ω.cm, double-sided alkali-washed texture;

[0064] (1) Constant source boron spin-coating—use 1.5-2.5mL of immersion solution to spin on the silicon wafer by spin-coating, and then drop 0.3-0.6ml of boron source to spin on the silicon wafer. The spin coating method can produce a higher square resistance of 130-200ohm, and the uniformity STD: 9-10;

[0065] (2) Drying—on a chain machine at a temperature of 180-250°C and a drying time of 40-80s;

[0066] (3) Entering the boat - the temperature is maintained at 750-850°C, the nitrogen flow rate is 1500-2500sccm, and the time is about 6-15min;

[0067] (4) Leak detection - the nitrogen flow rate is 1500-2500sccm, and the pressure is controlled at 100-200pa;

[0068] (5) Heating Oxidation—The temperature rises to 950-1000°C, the ...

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