阅读说明：本技术 激光se电池的制备方法 (Preparation method of laser SE battery ) 是由 任常瑞 张佳舟 赵潇祺 王敏 符黎明 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种激光SE电池的制备方法,包括激光掺杂和去PSG,还包括液相沉积磷源和热氧化,在激光掺杂之后,先液相沉积磷源,再热氧化,且热氧化在去PSG之前实施。本发明可以使轻掺区的近表面区有更多的活性P原子反应生成PSG,使轻掺区的PSG层增厚,使轻掺区的活性磷原子数目减少,降低轻掺区近表面区的掺杂浓度,而重掺区表面浓度基本不变,达到定向调控轻掺区的目的,从而使电池片表面复合减少,开压提高,电性能更优。(The invention discloses a preparation method of a laser SE battery, which comprises laser doping and PSG removal, and also comprises a liquid phase deposition phosphorus source and thermal oxidation. The invention can make the near surface area of the lightly doped area have more active P atoms to react to generate PSG, thicken the PSG layer of the lightly doped area, reduce the number of active phosphorus atoms of the lightly doped area, reduce the doping concentration of the near surface area of the lightly doped area, and basically keep the surface concentration of the heavily doped area unchanged, thereby achieving the purpose of directionally regulating and controlling the lightly doped area, reducing the surface recombination of a battery piece, improving the open voltage and having better electrical property.)

1. The preparation method of the laser SE battery comprises laser doping and PSG removal, and is characterized by further comprising liquid phase deposition of a phosphorus source and thermal oxidation, wherein after laser doping, the phosphorus source is firstly liquid phase deposited, then thermal oxidation is carried out, and thermal oxidation is carried out before PSG removal.

2. The method for preparing a laser SE cell as claimed in claim 1, wherein the liquid phase deposition phosphorous source is spin coated, spray coated or roll coated.

3. The method for preparing a laser SE cell as claimed in claim 2, wherein the phosphorus source is phosphoric acid, P₂O₅Or polyphosphoric acid.

4. The method for preparing a laser SE cell according to claim 3, wherein the concentration of the phosphorus source is 0.05-2.5 mol/L.

5. The method for preparing a laser SE cell according to claim 4, wherein the deposition thickness of the phosphorus source is 0.1-20 μm.

6. The method for manufacturing a laser SE cell according to claim 5, characterized in that the thermal oxidation is carried out in a chain furnace or a tube furnace.

7. The method for manufacturing a laser SE cell according to claim 6, wherein the atmosphere of the thermal oxidation is oxygen, a mixed gas of nitrogen and oxygen, or a mixed gas of water and oxygen.

8. The method for preparing a laser SE cell according to claim 7, wherein the temperature of the thermal oxidation is 650-900 ℃.

9. The method for preparing a laser SE cell according to claim 8, characterized in that the thermal oxidation time is 30 s-1 h.

10. The method for preparing a laser SE cell according to claim 9, characterized in that the specific steps comprise:

1) removing the damaged layer on the front surface of the silicon wafer and then texturing;

2) performing tubular diffusion on the silicon wafer subjected to texturing;

3) carrying out laser doping on the silicon wafer subjected to tubular diffusion;

4) performing liquid phase deposition on the silicon wafer subjected to laser doping to obtain a phosphorus source;

5) carrying out thermal oxidation on the silicon wafer subjected to liquid phase deposition;

6) removing PSG and edge junction of the silicon wafer subjected to thermal oxidation;

7) coating the silicon wafer after PSG and edge junction removal;

8) and (4) carrying out silk-screen printing and sintering on the silicon wafer after the film coating is finished.

Technical Field

The invention relates to a preparation method of a laser SE battery.

Background

Solar photovoltaic power generation has become a new industry which is concerned and developed intensively worldwide due to the characteristics of cleanness, safety, convenience, high efficiency and the like. In recent years, the production of crystalline silicon solar cells is rapidly developed, and the technology is continuously improved.

In the current solar technology, the PERC technology is mature, and in order to improve the conversion rate, the SE technology is the first choice of various photovoltaic enterprises. In the technical route of PERC + SE, the lightly doped region mainly plays a role of forming a built-in electric field to separate electron-hole pairs, while the heavily doped region plays a role of contacting with metal, and the two have different requirements on doping curves. The application of laser doping technology enables the metal contact part to be further optimized, but laser doping energy is limited, and higher laser energy can obtain better metal contact, and the number of defects in a heavily doped region is increased due to laser damage, so that the electrical property is influenced. In order to balance the electrical property gain and loss caused by metal contact and laser damage, the doping of the lightly doped region cannot be further reduced, and the space for electrical property increase is limited.

On the basis, the preparation process of the selective emitter is further optimized, so that the doping of the lightly doped region can be further reduced, and the directional regulation and control of the diffusion distribution of the lightly doped region are particularly important.

Disclosure of Invention

The invention aims to provide a preparation method of a laser SE cell, which can enable more active P atoms to react on a near-surface region of a lightly doped region to generate PSG, thicken a PSG layer of the lightly doped region, reduce the number of active phosphorus atoms of the lightly doped region, reduce the doping concentration of the near-surface region of the lightly doped region, and basically keep the surface concentration of a heavily doped region unchanged, thereby achieving the purpose of directionally regulating and controlling the lightly doped region, reducing the surface recombination of a cell, improving the open voltage and having better electrical property.

In order to achieve the above object, the present invention provides a method for preparing a laser SE cell, which includes laser doping and PSG removal, and further includes liquid phase deposition of a phosphorus source and thermal oxidation, wherein after the laser doping, the liquid phase deposition of the phosphorus source is performed, and thermal oxidation is performed before the PSG removal.

Preferably, the liquid phase deposition phosphorus source is spin-coated, spray-coated or roll-coated.

Preferably, the phosphorus source is phosphoric acid or P₂O₅Or polyphosphoric acid.

Preferably, the concentration of the phosphorus source is 0.05-2.5 mol/L.

Preferably, the deposition thickness of the phosphorus source is 0.1-20 μm.

Preferably, the thermal oxidation is carried out in a chain furnace or a tube furnace.

Preferably, the atmosphere of the thermal oxidation is oxygen, a mixed gas of nitrogen and oxygen or a mixed gas of water and oxygen.

Preferably, the temperature of the thermal oxidation is 650-900 ℃.

Preferably, the time of the thermal oxidation is 30s to 1 h.

Preferably, the preparation method of the laser SE battery comprises the following specific steps:

1) removing the damaged layer on the front surface of the silicon wafer and then texturing;

2) performing tubular diffusion on the silicon wafer subjected to texturing;

3) carrying out laser doping on the silicon wafer subjected to tubular diffusion, and forming a heavily doped region on the front side of the silicon wafer;

4) performing liquid phase deposition of a phosphorus source on the silicon wafer subjected to laser doping, wherein the deposited phosphorus source covers the front surface of the silicon wafer;

5) carrying out thermal oxidation on the silicon wafer subjected to liquid phase deposition to redistribute the light and heavy doped regions;

6) removing PSG and edge junction of the silicon wafer subjected to thermal oxidation;

7) coating the silicon wafer after PSG and edge junction removal, and depositing a silicon nitride film with antireflection and passivation effects on the front surface of the silicon wafer;

8) and (3) silk-screen printing and sintering the silicon wafer after film coating, printing a back electrode, a back electric field and a positive electrode, sintering, and metalizing the electrode to obtain the cell with the selective emitter.

The invention has the advantages and beneficial effects that: the preparation method of the laser SE cell can enable the near-surface region of the lightly doped region to have more active P atoms to react to generate PSG, thicken the PSG layer of the lightly doped region, reduce the number of active phosphorus atoms of the lightly doped region, reduce the doping concentration of the near-surface region of the lightly doped region, and basically keep the surface concentration of the heavily doped region unchanged, so that the aim of directionally regulating and controlling the lightly doped region is fulfilled, the surface recombination of a cell is reduced, the open voltage is improved, and the electrical property is better.

After laser doping is finished, a lightly doped region and a heavily doped region are formed on the front surface of the silicon wafer, and the PSG layer of the heavily doped region is excitedThe light is destroyed and the PSG layer of the lightly doped region remains. In the invention, liquid phase deposition phosphorus source and thermal oxidation are added between laser doping and PSG removal, and because of the existence of the PSG layer in the lightly doped region, the phosphorus source deposited in the liquid phase diffuses in the thermal oxidation process, the PSG layer in the lightly doped region can play a role of blocking, and a large amount of free P can be accumulated on Si/SiO₂Interface, free P reacts to form a large amount of P under the action of oxygen₂O₅And further reacts with Si at the interface to generate PSG, so that a PSG layer of the lightly doped region is thickened, the number of active P atoms of the lightly doped region is reduced, and the near-surface region doping concentration of the lightly doped region is reduced; and the reaction in the heavily doped region is inconsistent with the diffusion process of the lightly doped region because the PSG layer is damaged by laser, so that the obvious doping change trend can not occur.

Detailed Description

The following further describes embodiments of the present invention with reference to examples. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

The invention provides a preparation method of a laser SE battery, which comprises the following steps:

1) removing the damaged layer on the front surface of the silicon wafer and then texturing;

2) performing tubular diffusion on the silicon wafer subjected to texturing;

3) carrying out laser doping on the silicon wafer subjected to tubular diffusion, and forming a heavily doped region on the front side of the silicon wafer;

4) performing liquid phase deposition of a phosphorus source on the silicon wafer subjected to laser doping, wherein the deposited phosphorus source covers the front surface of the silicon wafer; the liquid phase deposition phosphorus source adopts spin coating, spray coating or roll coating; the phosphorus source is phosphoric acid or P₂O₅Or an organic solution of polyphosphoric acid; the concentration of the phosphorus source is 0.05-2.5 mol/L; the deposition thickness of the phosphorus source is 0.1-20 mu m;

5) carrying out thermal oxidation on the silicon wafer subjected to liquid phase deposition to redistribute the light and heavy doped regions; thermal oxidation is carried out in a chain furnace or a tubular furnace, the atmosphere is oxygen, mixed gas of nitrogen and oxygen or mixed gas of water and oxygen, the temperature is 650-900 ℃, and the time is 30 s-1 h;

6) removing PSG and edge junction of the silicon wafer subjected to thermal oxidation;

7) coating the silicon wafer after PSG and edge junction removal, and depositing a silicon nitride film with antireflection and passivation effects on the front surface of the silicon wafer;

8) and (3) silk-screen printing and sintering the silicon wafer after film coating, printing a back electrode, a back electric field and a positive electrode, sintering, and metalizing the electrode to obtain the cell with the selective emitter.

The specific embodiment of the invention is as follows: