CN-115274404-B - Modified tunneling oxide layer, preparation method, TOPCon structure, preparation method and solar cell

CN115274404BCN 115274404 BCN115274404 BCN 115274404BCN-115274404-B

Abstract

The invention provides a modified tunneling oxide layer, a preparation method, a TOPCon structure, a preparation method and a solar cell, wherein the modified tunneling oxide layer is prepared by plasma surface treatment, and the content of SiO x ,Si 4+ in SiO x is more than or equal to 18%. Compared with the silicon oxide layer prepared by the prior art, the diffusion rate of boron in the modified silicon oxide layer is low, so that the damage of boron to the tunneling oxide layer is effectively reduced, the integrity of the silicon oxide layer is improved, the chemical passivation effect is maintained, and the performance index of TOPCon structures can be remarkably improved by the modified tunneling oxide layer.

Inventors

YAN BAOJIE
ZENG YUHENG
XING HAIYANG
YE JICHUN
LIU WEI
LIAO MINGDUN
MA DIAN
LIN NA
DING ZETAO

Assignees

中国科学院宁波材料技术与工程研究所

Dates

Publication Date: 20260512
Application Date: 20220707

Claims (8)

1. The preparation method of the modified tunneling oxide layer is characterized by comprising the following steps of: S1, forming a SiO x layer on the surface of a semiconductor substrate by adopting an ion-free bombardment oxidation method; S2, treating the surface of SiO x by using plasma with hydrogen and oxygen-containing gas as treatment atmosphere to obtain a modified tunneling oxide layer, wherein the oxygen-containing gas is selected from any one of N 2 O、CO 2 、O 2 , the content of Si 4+ in the modified tunneling oxide layer is 18% or more, and the thickness is 1-4 nm.
2. The method according to claim 1, wherein the ion-free bombardment oxidation method in the step S1 is selected from the group consisting of an oxidizing gas oxidation method, a low-temperature oxidation method and a chemical agent oxidation method.
3. The method for preparing a modified tunnel oxide layer according to claim 1, wherein the step S2 is performed in a PECVD apparatus.
4. The method according to claim 3, wherein the plasma treatment method in the step S2 is continuous plasma treatment or pulsed plasma treatment.
5. The modified tunneling oxide layer is prepared by the preparation method according to any one of claims 1-4, wherein the modified tunneling oxide layer is SiO x subjected to plasma surface treatment, the content of Si 4+ in the modified tunneling oxide layer is 18% or more, and the thickness is 1-4 nm.
6. A TOPCon structure comprising the modified tunnel oxide layer of claim 5.
7. A preparation method of TOPCon structures is characterized by comprising the steps of cleaning a semiconductor substrate, preparing a modified tunneling oxide layer, preparing a doped amorphous silicon layer and annealing, wherein the preparation method of any one of claims 1-4 is adopted for preparing the modified tunneling oxide layer.
8. A solar cell comprising the TOPCon structure of claim 6.

Description

Modified tunneling oxide layer, preparation method, TOPCon structure, preparation method and solar cell Technical Field The invention relates to the technical field of solar cells, in particular to a modified tunneling oxide layer, a preparation method, a TOPCon structure, a preparation method and a solar cell. Background The tunneling oxide passivation contact structure (TOPCon) is a novel crystalline silicon solar cell structure proposed by the German French Hough study, and the core of the structure is to passivate the surface of a silicon wafer by adopting an ultrathin silicon oxide layer and doped polycrystalline silicon laminated structure. The passivation mechanism of the tunneling silicon oxide passivation contact structure mainly derives from the chemical passivation effect of the interface silicon oxide layer and the field passivation effect of doping atoms, so that the integrity of the interface silicon oxide is improved, and the surface chemical passivation effect is improved. TOPCon the preparation of the battery comprises the steps of cleaning and texturing, diffusing a boron emitter, etching, preparing SiO 2 on the back surface, PECVD heavy doping polycrystalline silicon, high-temperature annealing, front surface alumina, si 3N4 and screen printing. For the tunneling silicon oxide passivation contact technology, an n-type phosphorus doped polysilicon film is adopted for electron collection, and a p-type boron doped polysilicon film is adopted for hole collection. The n-type passivation contact technology has good effect and is widely accepted as a next-generation industrial high-efficiency crystalline silicon battery technology. The prior art adopts a Low Pressure Chemical Vapor Deposition (LPCVD) method to grow polysilicon, but LPCVD has the problems of low in-situ doping film forming rate, secondary doping, complicated process, coiling plating, long etching time, periodic maintenance of equipment and high cost. The Plasma Enhanced Chemical Vapor Deposition (PECVD) technology can solve the problems, the efficiency of the currently made better n-type TOPCon battery can reach 25.5%, but the cost of an n-type silicon wafer for the n-type TOPCon battery is high, and silver paste is needed to be used on the back surface of the n-type TOPCon battery, so that the cost is increased. In contrast, the p-type TOPCon battery adopts a low-cost p-type silicon wafer, and the back surface can adopt low-cost aluminum paste, so that the battery cost can be obviously reduced, and the product competitiveness is improved. However, the main problem faced in developing p-type TOPCon cells is that the passivation quality of the p-type TOPCon structure is poor and it is difficult to meet the requirements. The development of the high-performance p-type TOPCon technology is beneficial to increasing the industrial technology reserve and promoting the industrial technology development. In addition, the p-type TOPCon technology can also be used for novel high-efficiency battery technologies such as TBC batteries, laminated batteries and the like. Thus, there is an urgent need to develop and advance the p-type TOPCon technology. The PECVD technology is a technical route suitable for preparing boron doped polysilicon, however, the existing silicon oxide preparation technology still has various problems, and a p-type TOPCon structure with high performance can not be obtained by matching with the PECVD technology. The existing preparation method of the silicon oxide film comprises a plasma assisted laughing gas oxidation method, a nitric acid oxidation method and a thermal oxygen oxidation method, wherein a large number of defects are introduced at an interface due to oxygen plasma bombardment, so that a passivation effect is poor, the nitric acid oxidation method is used, the silicon oxide surface is loose, the silicon oxide is damaged in the cleaning and transferring process, and the thermal oxygen oxidation method is used, so that the silicon oxide is thick and poor in contact although the silicon oxide quality is good. Finally, the optimal passivation effect in p-TOPCon can only reach 700mV-705mV based on the silicon oxide prepared by the three methods, the corresponding single-sided saturation current density (J 0) is usually above 15fA/cm 2, and the iV oc is further reduced in the subsequent sintering process of the printed electrode, so that the performance of the final device is reduced. Disclosure of Invention Aiming at the defects of the prior art, the technical problem to be solved by the invention is how to improve the passivation quality of TOPCon structures so as to prepare the high-efficiency solar cell. In order to solve the above problems, a first aspect of the present invention provides a modified tunneling oxide layer, wherein the ratio of the SiO x,Si4+ content in the SiO x, which is subjected to the plasma surface treatment, is 18% or more. Further, the thickness of the modified tunneling oxide layer is