阅读说明：本技术 一种双面晶体硅太阳电池及其制备方法 (Double-sided crystalline silicon solar cell and preparation method thereof ) 是由 沈梦超 张梦葛 黄海冰 于 2020-06-11 设计创作，主要内容包括：本发明公开一种双面晶体硅太阳电池制备方法,先在硅片上制备硼掺杂面所需表面形貌,然后进行硼掺杂,利用硼掺杂过程表面生成的氧化层作为掩膜制备磷掺杂面所需表面形貌并进行磷掺杂；通过氢氟酸水上漂去除硅片边沿的氧化层；通过边沿抛光对硅片进行边沿隔离,利用硼掺杂面和磷掺杂面的氧化层作为掩膜保护硅片两面掺杂层不被破坏；最后在硅片两面制作钝化层和金属电极。进一步,本发明还公开一种通过这种方法制得的双面晶体硅太阳电池。该方法工艺过程简单,制作成本低,可以匹配不同类型的电池衬底和电池结构,并具有优良的边沿隔离效果,能大大降低双面晶体硅太阳电池的边沿漏电。(The invention discloses a preparation method of a double-sided crystalline silicon solar cell, which comprises the steps of firstly preparing the surface appearance required by a boron doping surface on a silicon chip, then carrying out boron doping, preparing the surface appearance required by a phosphorus doping surface by using an oxidation layer generated on the surface in the boron doping process as a mask, and carrying out phosphorus doping; removing an oxide layer at the edge of the silicon wafer by hydrofluoric acid water bleaching; edge isolation is carried out on the silicon wafer through edge polishing, and oxide layers of a boron doped surface and a phosphorus doped surface are used as masks to protect doped layers on two sides of the silicon wafer from being damaged; and finally, manufacturing a passivation layer and a metal electrode on two sides of the silicon wafer. Further, the invention also discloses a double-sided crystalline silicon solar cell prepared by the method. The method has the advantages of simple process and low manufacturing cost, can be matched with different types of cell substrates and cell structures, has excellent edge isolation effect, and can greatly reduce the edge leakage of the double-sided crystalline silicon solar cell.)

1. A preparation method of a double-sided crystalline silicon solar cell is characterized by comprising the following steps:

providing a silicon wafer, wherein one surface of the silicon wafer is selected as a boron doped surface, and the other surface of the silicon wafer is selected as a phosphorus doped surface;

preparing a surface appearance required by a boron-doped surface on the surface of a silicon wafer;

carrying out boron doping on the boron doping surface, manufacturing a boron doping layer, and growing a boron oxidation layer on the surface of the boron doping layer;

removing a boron diffusion oxide layer formed on a phosphorus doped surface and an edge in the manufacturing process of the boron doped layer by a hydrofluoric acid water bleaching method;

preparing a surface appearance required by a phosphorus doping surface on the phosphorus doping surface, and simultaneously removing a boron doping layer which is formed around the phosphorus doping surface and the edge in the manufacturing process of the boron doping layer, wherein the boron oxidation layer is partially etched or the thickness of the boron oxidation layer is kept unchanged;

manufacturing a battery phosphorus doped layer on the phosphorus doped surface, and growing a phosphorus oxide layer on the surface of the phosphorus doped layer;

removing a phosphorus diffusion layer formed at the edge of a phosphorus doped surface in the manufacturing process of the phosphorus doped layer by a hydrofluoric acid water bleaching mode;

using an alkali polishing mode to remove a phosphorus-extending doped layer formed at the edge of a phosphorus doped surface in the manufacturing process of the phosphorus doped layer to carry out edge isolation on the silicon wafer, and simultaneously removing phosphorus elements attached to the surface of a boron oxide layer in the manufacturing process of the phosphorus doped layer, wherein after the alkali polishing, the boron oxide layer and the phosphorus oxide layer are not completely etched;

removing the boron oxide layer left on the boron doped surface and the phosphorus oxide layer left on the phosphorus doped surface in a hydrofluoric acid cleaning mode;

passivating the surfaces of the boron doped surface and the phosphorus doped surface;

and preparing metal electrodes on the boron doped surface and the phosphorus doped surface.

2. The method for manufacturing a double-sided crystalline silicon solar cell according to claim 1, wherein the thickness of the boron oxide layer grown on the surface of the boron doped layer is 30 to 300 nm.

3. The method according to claim 1, wherein the thickness of the phosphorus oxide layer grown on the surface of the phosphorus doped layer is at least 5nm thinner than the thickness of the boron oxide layer after the preparation of the surface morphology required for the phosphorus doped surface.

4. The method for manufacturing a double-sided crystalline silicon solar cell according to claim 3, wherein the thickness of the phosphorus oxide layer grown on the surface of the phosphorus doped layer is 3-20 nm.

5. The method of claim 1, wherein the sheet resistance of the boron doped layer is about 20-500 Ω/□, and the sheet resistance of the phosphorus doped layer is 20-500 Ω/□.

6. The method for preparing the double-sided crystalline silicon solar cell according to claim 1, wherein the hydrofluoric acid water float-up condition for removing the boron diffusion-surrounding oxide layer is as follows: the concentration of the hydrofluoric acid solution is 0.5-40%, and the process time is 10-1200 s.

7. The method for preparing the double-sided crystalline silicon solar cell as claimed in claim 1, wherein the hydrofluoric acid water float-up condition for removing the phosphorus diffusion oxide layer is as follows: the concentration of the hydrofluoric acid solution is 0.5-10%, and the process time is 5-300 s.

8. The method for manufacturing a double-sided crystalline silicon solar cell according to claim 1, wherein the conditions of the alkali polishing are as follows: selecting aqueous solution of potassium hydroxide or sodium hydroxide, wherein the concentration of the aqueous alkali is 0.5-20%, the concentration of the polishing additive is 0.02-5%, the temperature of the solution is 45-85 ℃, and the polishing time is 10-300 s; the polishing additive is used to reduce the reaction rate of the oxide layer in the alkaline solution.

9. The method for manufacturing a double-sided crystalline silicon solar cell according to claim 1, wherein conditions for cleaning the boron oxide layer and the phosphorus oxide layer with hydrofluoric acid are as follows: the concentration of hydrofluoric acid is 0.5-30%, and the cleaning time is 2-120 min.

10. A double-sided crystalline silicon solar cell, characterized by being prepared by the method of any one of claims 1 to 9, comprising a silicon wafer substrate; a boron doping layer, a boron doping surface passivation layer and a boron doping surface metal electrode which are sequentially formed on one surface of a silicon chip substrate; and the phosphorus doped layer, the phosphorus doped surface passivation layer and the phosphorus doped surface metal electrode are sequentially formed on the other surface of the silicon chip substrate.

Technical Field

The invention belongs to the technical field of crystalline silicon solar cell manufacturing, and particularly relates to a double-sided crystalline silicon solar cell preparation method and a double-sided crystalline silicon solar cell prepared by the method.

Background

Solar energy is an environment-friendly energy, and solar cells convert solar energy into electric energy by utilizing a photovoltaic effect, and become the most promising energy solution in the future. The crystalline silicon solar cell is one of the main technical schemes of the solar cell due to the advantages of wide raw material source, low manufacturing cost and the like. In the crystalline silicon solar cell, the double-sided cell is doped with different types on two sides of the cell to form built-in electric fields on the two sides of the cell, so that the double-sided solar cell has excellent carrier collection capability, and can receive light on two sides to improve power generation capability. However, compared with a single-sided crystalline silicon solar cell, the double-sided crystalline silicon solar cell needs to perform different types of doping on two sides of the cell, so that in order to avoid interference between the two types of doping, an extra mask is often used on one side of the cell to block the doping on the other side, the process is relatively complicated, the preparation cost is increased, and the different types of doping exist at the edge of the double-sided crystalline silicon solar cell at the same time, so that the electric leakage at the edge of the cell is increased, and the performance of the cell is reduced.

Disclosure of Invention

In view of the above, the invention provides a method for preparing a double-sided crystalline silicon solar cell, which comprises the steps of firstly preparing a surface morphology required by a boron doping surface on a silicon wafer, then carrying out boron doping, preparing a surface morphology required by a phosphorus doping surface by using an oxidation layer generated on the surface of the boron doping layer as a mask, and carrying out phosphorus doping; removing a phosphorus oxide layer on the edge of the silicon wafer by hydrofluoric acid water bleaching; edge isolation is carried out on the silicon wafer through edge polishing, and oxide layers of a boron doped surface and a phosphorus doped surface are used as masks to protect doped layers on two sides of the silicon wafer from being damaged; and finally, manufacturing a passivation layer and a metal electrode on two sides of the silicon wafer. Further, the invention also discloses a double-sided crystalline silicon solar cell prepared by the method. The method has the advantages of simple process and low manufacturing cost, can be matched with different types of cell substrates and cell structures, has excellent edge isolation effect, and can greatly reduce the edge leakage of the double-sided crystalline silicon solar cell.

With reference to fig. 1, the method for manufacturing a double-sided crystalline silicon solar cell disclosed by the invention mainly comprises the following steps:

a silicon wafer is selected. Can be an n-type monocrystalline silicon piece, a p-type monocrystalline silicon piece, an n-type polycrystalline silicon piece or a p-type polycrystalline silicon piece.

And selecting one surface of the silicon wafer as a boron doped surface to prepare the surface appearance required by the boron doped surface. The surface morphology required by the boron doped surface can be prepared by a polishing or texturing method. The other surface is the phosphorus doped surface.

And carrying out boron doping on the boron doped surface, manufacturing a boron doped layer of the battery, and growing a boron oxide layer on the surface of the boron doped surface. The boron doping can be selected from uniform doping over the whole surface, local doping or selective doping. The boron doping can be realized by one or more of tubular boron diffusion, boron slurry doping, boron ion implantation and the like. The boron oxide layer is full-face, and the growth of the boron oxide layer is usually formed in the impurity redistribution stage of the method, and can also be formed by oxidizing the silicon wafer again after boron doping. After the boron oxide layer is formed, the back surface and the edge of the boron doped surface can form a boron doping layer and a boron oxide layer due to the phenomenon of diffusion. The sheet resistance of the boron doped layer is about 20-500 omega/□, and the thickness of the boron oxide layer on the boron doped surface is about 30-300 nm.

And removing the diffusion boron oxide layer. Particularly, a hydrofluoric acid water bleaching method can be selected to remove the boron-diffusion oxide layer on the back and the edge of the boron-doped surface. The technological conditions of hydrofluoric acid bleaching in water can be as follows: the concentration of the hydrofluoric acid solution is 0.5-40%, and the process time is 10-1200 s.

And taking the back surface of the boron doped surface as a phosphorus doped surface, preparing the surface appearance required by the phosphorus doped surface, and removing the extension boron doped layer. The surface morphology required by the phosphorus doped surface can be prepared by methods of texturing with alkali, polishing with alkali, etching with acid and texturing with acid. In the process, the boron doping surface is provided with the boron oxidation layer, so that the boron oxidation layer has a mask effect in the surface appearance process required by the preparation of the phosphorus doping surface, and the boron doping surface can be protected from being damaged. After the surface appearance required by the preparation of the phosphorus doped surface is finished, the thickness of the boron oxide layer is unchanged or is reduced to some extent.

And carrying out phosphorus doping on the phosphorus doped surface, manufacturing a phosphorus doped layer of the battery, and growing a phosphorus oxide layer on the surface of the phosphorus doped layer. The phosphorus doping can be selected from uniform doping, local doping and selective doping on the whole surface. The phosphorus doping can be realized by one or more of tubular phosphorus diffusion, phosphorus slurry doping, phosphorus ion implantation and the like. Similarly, the phosphorus oxide layer is full-surface, and the growth of the phosphorus oxide layer is usually formed in the impurity redistribution stage of the method, and can also be formed by oxidizing the silicon wafer again after phosphorus doping. After the phosphorus oxide layer is formed, a phosphorus diffusion layer and a phosphorus diffusion oxide layer are formed at the edge of the silicon wafer due to the winding and expansion phenomenon, and a layer of phosphorus element is attached to the surface of the boron oxide layer of the boron doped surface due to the winding and expansion phenomenon. The square resistance of the phosphorus doped layer is about 20-500 omega/□, the thickness of a phosphorus oxide layer on the phosphorus doped surface is about 3-20nm, and the thickness of the phosphorus oxide layer is more than 5nm thinner than the residual thickness of a boron oxide layer after the surface morphology required by the preparation of the phosphorus doped surface is finished.

And removing the phosphorus diffusion layer. Particularly, a hydrofluoric acid water floating method can be used for removing the phosphorus diffusion surrounding oxide layer. In the process of bleaching hydrofluoric acid water, the boron doped surface is in downward contact with hydrofluoric acid, the edge of the silicon wafer is also in contact with hydrofluoric acid due to the surface tension of the hydrofluoric acid solution, the phosphorus diffusion oxide layer is removed, and the thickness of the phosphorus oxide layer on the surface of the phosphorus doped surface is unchanged. Because the thickness of the boron oxide layer on the boron doping surface is larger than that of the phosphorus diffusion oxide layer, the boron oxide layer can not be completely removed. Hydrofluoric acid water bleaching condition: the concentration of the hydrofluoric acid solution is 0.5-10%, and the process time is 5-300 s. After rinsing with hydrofluoric acid water, the boron oxide layer thickness is reduced by about 3-20nm, and the remaining thickness is above 5 nm. And after the phosphorus diffusion layer is removed, the phosphorus diffusion layer is exposed at the edge of the silicon wafer.

And removing the phosphorus diffusion layer and carrying out edge isolation on the silicon wafer. The method for polishing the silicon wafer by using the alkali is used for removing the phosphorus diffusion doped layer, and the boron doped surface of the silicon wafer is provided with the boron oxide layer and the phosphorus doped surface is provided with the phosphorus oxide layer, so that the reaction rate of the boron oxide layer and the phosphorus oxide layer in the alkali solution is low, and the boron doped layer and the phosphorus doped layer cannot be corroded by the alkali solution. The edge of the silicon chip is provided with a phosphorus diffusion layer, the reaction rate of the phosphorus diffusion layer and the alkaline solution is high, and the phosphorus diffusion layer is corroded by the alkaline solution, so that the edge isolation is realized. The alkali polishing is aqueous solution of potassium hydroxide or sodium hydroxide. Alkali polishing conditions: selecting sodium hydroxide or potassium hydroxide solution, wherein the concentration of the alkali solution is 0.5-20%, the concentration of the polishing additive is 0.02-5%, the temperature of the solution is 45-85 ℃, and the polishing time is 10-300 s. The polishing additive refers to chemicals containing fatty alcohol-polyoxyethylene ether and the like, and has the function of reducing the reaction rate of an oxide layer in an alkali solution. After the alkali polishing, the thickness of the boron oxide layer and the phosphorus oxide layer is reduced, but the thickness of the boron oxide layer and the phosphorus oxide layer is still remained, and a layer of phosphorus element attached to the surface of the boron oxide layer is removed.

And removing the boron oxide layer and the phosphorus oxide layer. And removing the boron oxide layer and the phosphorus oxide layer by using a hydrofluoric acid cleaning method. Cleaning conditions of hydrofluoric acid: the concentration of hydrofluoric acid is 0.5-30%, and the cleaning time is 2-120 min.

The surface of the silicon chip is passivated, and specifically, one or more of aluminum oxide, silicon nitride, silicon oxide, silicon oxynitride, magnesium fluoride and zinc sulfide can be selected and superposed to passivate the surface of the silicon chip. The passivation layer is not limited in fabrication manner.

And preparing the metal electrode required by the battery. The metal electrode can be manufactured by selecting methods such as electroplating, evaporation plating, screen printing and the like.

The invention has the following beneficial effects:

the invention can independently control the surface appearance and the doping concentration of the boron doping surface and the phosphorus doping surface through simple process setting, cannot influence each other and has wider process window. The invention can effectively isolate the edge of the silicon chip, reduce the problem of electric leakage at the edge of the solar battery and improve the performance of the battery.

The invention has wide applicability, and can be applied to different types of battery structures, such as a p-type double-sided battery, a p-type back junction battery, an n-type double-sided battery, an n-type back junction battery and the like.

Drawings

FIG. 1 is a schematic flow chart of a preparation method of a double-sided crystalline silicon solar cell according to the invention;

fig. 2 is an n-type positive junction double-sided battery prepared by the method described in example 1, wherein: the manufacturing method comprises the following steps of (1) 11-n type monocrystalline silicon piece, 12-boron doped layer, 13-phosphorus doped layer, 14-boron doped surface passivation layer, 15-phosphorus doped surface passivation layer, 16-boron doped surface metal electrode and 17-phosphorus doped surface metal electrode;

fig. 3 is an n-type positive junction double-sided battery prepared by the method described in example 2, wherein: the silicon chip comprises a 21-p type monocrystalline silicon piece, a 22-phosphorus doped layer, a 23-boron doped layer, a 24-phosphorus doped surface passivation layer, a 25-boron doped surface passivation layer, a 26-phosphorus doped surface metal electrode and a 27-boron doped surface metal electrode.

Detailed Description

The invention will be further explained with reference to specific embodiments and the accompanying drawings in which: