阅读说明：本技术 一种隧穿氧化钝化接触电池、制备方法及设备 (Tunneling oxidation passivation contact battery, preparation method and equipment ) 是由 韩培丁 张良 于 2021-07-09 设计创作，主要内容包括：本发明提供了一种隧穿氧化钝化接触电池、制备方法及设备,该方法包括：提供N型的硅基底,对硅基底清洗后制绒。然后在硅基底的表面进行硼扩散制备PN结。接着去除硅基底在硼扩散时背面形成的硼硅玻璃,以及去除扩散至硅基底的硼,采用臭氧水对硅基底的背面进行清洗和氧化,形成隧穿氧化层,进一步的在隧穿氧化层上制备多晶硅层,在PN结表面制备氧化铝层,以及在氧化铝层和掺杂多晶硅层上制备上氮化硅层和下氮化硅层,在上氮化硅层和下氮化硅层上分别制备第一电极和第二电极,该方法通过采用臭氧水清洗硅基底的背面,臭氧水对硅基底的背面进行氧化形成的隧穿氧化层,均匀性好,使的制备出的隧穿氧化钝化接触电池的光电转化效率和良率更高。(The invention provides a tunneling oxidation passivation contact battery, a preparation method and equipment, wherein the method comprises the following steps: and providing an N-type silicon substrate, and cleaning the silicon substrate to make wool. Then, the surface of the silicon substrate is subjected to boron diffusion to prepare a PN junction. The method comprises the steps of cleaning the back surface of the silicon substrate by using ozone water, preparing a polycrystalline silicon layer on the tunneling oxide layer, preparing an aluminum oxide layer on the surface of a PN junction, preparing an upper silicon nitride layer and a lower silicon nitride layer on the aluminum oxide layer and the doped polycrystalline silicon layer, and preparing a first electrode and a second electrode on the upper silicon nitride layer and the lower silicon nitride layer respectively.)

1. A method for preparing a tunneling oxidation passivation contact battery is characterized by comprising the following steps:

s101: providing an N-type silicon substrate, and cleaning the silicon substrate to make wool;

s102: carrying out boron diffusion on the surface of the silicon substrate to prepare a PN junction;

s103: removing borosilicate glass formed on the back surface of the silicon substrate during boron diffusion, and removing boron diffused to the silicon substrate;

s104: cleaning and oxidizing the back surface of the silicon substrate by adopting ozone water to form a tunneling oxide layer;

s105: preparing a polysilicon layer on the tunneling oxide layer;

s106: preparing an aluminum oxide layer on the surface of the PN junction;

s107: preparing an upper silicon nitride layer and a lower silicon nitride layer on the aluminum oxide layer and the doped polycrystalline silicon layer;

s108: and respectively preparing a first electrode and a second electrode on the upper silicon nitride layer and the lower silicon nitride layer.

2. The method according to claim 1, wherein the step S103 includes:

putting the back surface of the silicon substrate into hydrofluoric acid, and removing the borosilicate glass;

and then putting the back surface of the silicon substrate into a mixed solution of nitric acid and hydrofluoric acid, and removing the back surface of the silicon substrate to the thickness of 0.5-1.5 mu m.

3. The method according to claim 1 or 2, wherein the step S104 is followed by:

and placing the structure formed in the step S104 in a nitrogen environment, heating to 450-700 ℃, and annealing for 5-30 minutes.

4. The method according to claim 3, wherein the step S105 includes:

and when the polycrystalline silicon layer is doped polycrystalline silicon, carrying out annealing treatment.

5. The method according to claim 4, wherein the step S105 includes:

and when the polycrystalline silicon layer is intrinsic silicon, phosphorus diffusion is carried out.

6. The method of claim 5, wherein the steps S103 and S104 are performed in one apparatus or a plurality of apparatuses.

7. The method according to claim 6, wherein a first holding tank for holding the hydrofluoric acid and a second holding tank for holding the mixed solution of the nitric acid and the hydrofluoric acid are provided in the one or more devices.

8. The method according to claim 1, wherein the step S101 includes:

and texturing the silicon substrate to form a pyramid-shaped light trapping structure.

9. An apparatus for making a tunnel oxide passivated contact cell, wherein the apparatus is operable to perform the method of any of claims 1-8.

10. A tunneling oxidation passivated contact cell prepared by the method of any of claims 1-8.

Technical Field

The invention relates to the technical field of photovoltaic power generation, in particular to a tunneling oxidation passivation contact battery, a preparation method and equipment.

Background

TOPCon cells, i.e., tunneling oxidation passivation contact cells, typically have a 1-2nm ultra-thin uniform oxide layer grown on their surface during fabrication. In order to improve the performance of the TOPCon cell, the oxide layer is required to have the characteristics of compactness, ultra-thinness and uniformity in the preparation process, the compact oxide layer can form good oxidation passivation on the surface of a silicon wafer, the ultra-thin oxide layer has small tunneling resistance and can realize quantum tunneling of electrons, the uniform oxide layer can enable the tunneling current to be uniformly distributed, and the non-uniform oxide layer can form the condition of uneven brightness in an EL test (electroluminescence, a characterization test method commonly used by solar cells).

At present, in the preparation process of the TOPCon battery, the most common thermal oxidation is to place a silicon wafer in an oxidizing atmosphere of 600-700 ℃ to form an oxide layer on the surface of the silicon wafer, but the method causes poor uniformity of the oxide layer and is greatly influenced by the environment, so that the efficiency and yield of the tunneling oxidation passivation contact battery cannot be stable all the time, the cost of a single watt is difficult to control, and the market competitiveness is lacked.

Disclosure of Invention

The invention aims to provide a tunneling oxidation passivation contact battery, a preparation method and equipment, which improve the photoelectric conversion efficiency and yield of the tunneling oxidation passivation contact battery.

To achieve the above object, in a first aspect, the present invention provides a method for preparing a tunneling oxidation passivation contact battery, the method comprising:

s101: and providing an N-type silicon substrate, and cleaning the silicon substrate to perform texturing. S102: and carrying out boron diffusion on the surface of the silicon substrate to prepare the PN junction. S103: removing borosilicate glass formed on the back surface of the silicon substrate during boron diffusion, and removing boron diffused to the silicon substrate, S104: cleaning and oxidizing the back surface of the silicon substrate by adopting ozone water to form a tunneling oxide layer, S105: preparing a polysilicon layer on the tunneling oxide layer, S106: preparing an aluminum oxide layer on the surface of the PN junction, and S107: preparing an upper silicon nitride layer and a lower silicon nitride layer on the aluminum oxide layer and the doped polysilicon layer, S108: and respectively preparing a first electrode and a second electrode on the upper silicon nitride layer and the lower silicon nitride layer.

The preparation method of the tunneling oxidation passivation contact battery provided by the embodiment of the invention has the beneficial effects that: the back surface of the silicon substrate is cleaned by adopting ozone water, and the ozone water oxidizes the back surface of the silicon substrate to form a tunneling oxidation layer, so that the uniformity is good, and the photoelectric conversion efficiency of the prepared tunneling oxidation passivation contact cell is higher.

In one possible implementation, the step S103 includes: and putting the back surface of the silicon substrate into hydrofluoric acid, removing the borosilicate glass, putting the back surface of the silicon substrate into a mixed solution of nitric acid and hydrofluoric acid, and removing the back surface of the silicon substrate to the thickness of 0.5-1.5 mu m. The beneficial effects are that: removing borosilicate glass formed on the back surface of the silicon substrate during boron diffusion, and removing boron diffused to a part of the silicon substrate.

In one possible implementation, after the step S104, the method includes: and placing the structure formed in the step S104 in a nitrogen environment, heating to 450-700 ℃, and annealing for 5-30 minutes. The beneficial effects are that: the formed tunneling oxide layer is subjected to molecular rearrangement by heating to the temperature of 450-700 ℃ in a nitrogen environment and annealing for 5-30 minutes, so that the structure of the tunneling oxide layer is more uniform and compact, the condition of poor EL is avoided, and the photoelectric conversion efficiency of the tunneling oxidation passivation contact cell is higher.

In one possible implementation, the step S105 includes: and when the polycrystalline silicon layer is doped polycrystalline silicon, carrying out annealing treatment. The beneficial effects are that: one embodiment of forming doped polysilicon is described.

In one possible implementation, the step S105 includes: and when the polycrystalline silicon layer is intrinsic silicon, phosphorus diffusion is carried out. The beneficial effects are that: another embodiment for forming doped polysilicon.

In one possible implementation, the steps S103 and S104 are performed in one device or a plurality of devices. The beneficial effects are that: according to actual production needs, one or more devices can be respectively adopted to complete the steps S103 and S104.

In a possible implementation, a first holding tank and a second holding tank are arranged in the equipment or the plurality of equipment, the first holding tank is used for holding the hydrofluoric acid, and the second holding tank is used for holding the mixed solution of the nitric acid and the hydrofluoric acid. The beneficial effects are that: through setting up first holding tank and second holding tank, and first holding tank is used for holding hydrofluoric acid, and the second holding tank is used for holding the mixed solution of nitric acid and hydrofluoric acid, realizes the completion of step S103 and step S104.

In one possible implementation, the step S101 includes: and texturing the silicon substrate to form a pyramid-shaped light trapping structure. The beneficial effects are that: avoid the reflection of light, improve photoelectric conversion efficiency.

In a second aspect, embodiments of the present invention provide an apparatus for preparing a tunnel oxide passivated contact cell, which apparatus may implement the method described above.

The equipment for preparing the tunneling oxidation passivation contact battery has the advantages that: the photoelectric conversion efficiency of the tunneling oxidation passivation contact cell is improved.

In a third aspect, embodiments of the present invention provide a tunneling oxidation passivated contact cell, which is prepared by the above method.

The tunneling oxidation passivation contact battery provided by the embodiment of the invention has the beneficial effects that: the photoelectric conversion efficiency of the tunneling oxidation passivation contact battery is improved, and the poor EL condition is avoided.

Drawings

Fig. 1 is a flow chart of a method for manufacturing a tunneling oxidation passivation contact battery according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the word "comprising" and similar words are intended to mean that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items.

The TOPCon battery is a tunneling oxidation passivation contact battery, and an ultrathin uniform oxide layer with the thickness of 1-2nm, namely a tunneling oxide layer, is generally grown on the surface of the TOPCon battery in the preparation process. In order to improve the performance of the TOPCon cell, the oxide layer is required to have the characteristics of compactness, ultra-thinness and uniformity in the preparation process, the compact oxide layer can form good oxidation passivation on the surface of a silicon wafer, the ultra-thin oxide layer has small tunneling resistance and can realize quantum tunneling of electrons, the uniform oxide layer can enable the tunneling current to be uniformly distributed, and the non-uniform oxide layer can form the condition of uneven brightness in an EL test (electroluminescence, a characterization test method commonly used by solar cells).

At present, the most common method for forming the oxide layer is to place the silicon wafer in an oxidation atmosphere of 600-.

In view of the problems in the prior art, an embodiment of the present invention provides a method for manufacturing a tunneling oxidation passivation contact battery, which is shown in fig. 1 and includes:

s101: and providing an N-type silicon substrate, and cleaning the silicon substrate to make wool.

In the step, in order to increase the photoelectric conversion efficiency and reduce the reflection of light, the silicon substrate is textured to form a pyramid-shaped light trapping structure.

S102: and carrying out boron diffusion on the surface of the silicon substrate to prepare the PN junction.

In this step, a PN junction is formed on the front surface of the silicon substrate. Of course, when boron is diffused, boron is further diffused to the back surface of the silicon substrate, and silicon and boron on the back surface of the silicon substrate also react to form a PN junction and borosilicate glass.

S103: removing the borosilicate glass formed on the back surface of the silicon substrate during boron diffusion, and removing the boron diffused to the silicon substrate.

Specifically, in the step, the back surface of the silicon substrate is placed in hydrofluoric acid, the hydrofluoric acid reacts with borosilicate glass, so that the borosilicate glass is removed, and further, after the borosilicate glass is removed, the back surface of the silicon substrate is continuously placed in a mixed solution of nitric acid and hydrofluoric acid, and the nitric acid oxidizes the back surface of the silicon substrate and simultaneously the hydrofluoric acid reacts with silicon oxide, so that a structure with the thickness of 0.5-1.5 microns is stripped from the back surface of the silicon substrate. It should be noted that the depth of boron diffusion into the silicon substrate is typically between 0.5-1.5 μm, so as to remove the boron diffused into the silicon substrate, i.e., the PN junction formed on the back side of the silicon substrate.

S104: and cleaning and oxidizing the back surface of the silicon substrate by adopting ozone water to form a tunneling oxide layer.

In the step, the back of the silicon substrate is cleaned and oxidized by ozone water, so that the stability and reliability of the treatment environment are ensured, the structure of the tunneling oxide layer formed on the back of the silicon substrate is more uniform, and the structure of the tunneling oxide layer is more stable.

More importantly, the formed tunneling oxide layer is placed in a tubular heating device, nitrogen is introduced into the tubular heating device, then the tubular heating device is heated to the temperature of 450-.

S105: and preparing a polysilicon layer on the tunneling oxide layer.

The step includes two implementation modes, the first mode is as follows: and when the polycrystalline silicon layer is doped polycrystalline silicon, annealing treatment is carried out. And the second method comprises the following steps: when the polysilicon layer is intrinsic silicon, phosphorus diffusion is performed.

S106: and preparing an aluminum oxide layer on the surface of the PN junction.

S107: an upper silicon nitride layer and a lower silicon nitride layer are prepared on the aluminum oxide layer and the doped polysilicon layer.

In this step, the upper silicon nitride layer and the lower silicon nitride layer respectively represent a silicon nitride layer on the front surface of the silicon substrate and a silicon nitride layer on the back surface of the silicon substrate.

S108: a first electrode and a second electrode are respectively prepared on the upper silicon nitride layer and the lower silicon nitride layer.

In the embodiment, the back surface of the silicon substrate is cleaned by adopting ozone water, the ozone water oxidizes the back surface of the silicon substrate to form the tunneling oxide layer, and then the tunneling oxide layer is heated to the temperature of 450-700 ℃ in a nitrogen environment and annealed for 5-30 minutes, so that the uniformity of the tunneling oxide layer is high, and the photoelectric conversion efficiency of the prepared tunneling oxidation passivation contact battery is higher.

In one possible implementation, one piece of equipment is provided with a first holding tank and a second holding tank, the first holding tank is used for holding hydrofluoric acid, the second holding tank is used for holding a mixed solution of nitric acid and hydrofluoric acid, and the method steps of step S103 and step S104 are completed.

In another possible implementation, a first holding tank and a second holding tank may be separately provided in the plurality of devices, where the first holding tank is used to hold hydrofluoric acid, and the second holding tank is used to hold a mixed solution of nitric acid and hydrofluoric acid, so as to complete the method steps of step S103 and step S104.

In another embodiment of the present disclosure, an apparatus for preparing a tunnel oxide passivated contact cell may perform the steps of the above method.

In this embodiment, the device can implement the above-mentioned preparation method, and improves the photoelectric conversion efficiency of the prepared tunneling oxidation passivation contact cell.

In yet another embodiment of the present disclosure, a method of making a tunnel oxide passivated contact cell is provided.

In the embodiment, the cell has high photoelectric conversion efficiency and high production stability.

The above description is only a specific implementation of the embodiments of the present application, but the scope of the embodiments of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the embodiments of the present application should be covered by the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.