CN-121975525-A - Low-concentration hydrofluoric acid composite etching liquid and preparation method and etching process thereof

CN121975525ACN 121975525 ACN121975525 ACN 121975525ACN-121975525-A

Abstract

The invention belongs to the technical field of photovoltaic wet etching, and particularly relates to a low-concentration hydrofluoric acid composite etching solution, a preparation method and an etching process thereof, wherein the low-concentration hydrofluoric acid composite etching solution comprises, by mass, 5% -10% of hydrofluoric acid, 2% -5% of an etching additive and the balance of water, the etching additive comprises, by mass, 8% -25% of a strong oxidant, 2% -5% of an etching accelerator, 0.5% -2% of an interface modification and mass transfer accelerator, 0.1% -3% of a product control and stabilizer, 0.1% -2% of an equipment compatible corrosion inhibitor and the balance of water, the strong oxidant is used for oxidizing silicon nitride to form a silicon oxynitride transition layer, the etching accelerator is used for providing HF molecules and HF 2 ‑ ions, and the product control and stabilizer is used for complexing SiF 6 2‑ ions generated by etching.

Inventors

REN JINZHI
Request for anonymity
LI JINGJING
Request for anonymity
ZUO GUOJUN

Assignees

常州捷佳创精密机械有限公司

Dates

Publication Date: 20260505
Application Date: 20260127

Claims (10)

1. The low-concentration hydrofluoric acid composite etching liquid is characterized by comprising the following components in percentage by mass: 5% -10% of hydrofluoric acid, 2% -5% of etching additive and the balance of water; The etching additive comprises the following components in percentage by mass: 8% -25% of strong oxidant, 2% -5% of etching accelerator, 0.5% -2% of interface modification and mass transfer accelerator, 0.1% -3% of product control and stabilizing agent, 0.1% -2% of equipment compatible corrosion inhibitor and the balance of water; The strong oxidizer is used to oxidize silicon nitride to form a silicon oxynitride transition layer, the etch promoter is used to provide HF molecules and HF 2 - ions, and the product control and stabilizer is used to complex the SiF 6 2- ions generated by the etch.
2. The low-concentration hydrofluoric acid composite etching liquid according to claim 1, The strong oxidant comprises any one or a combination of a plurality of hydrogen peroxide, potassium peroxymonosulfate, ammonium persulfate, sodium chlorate, potassium iodate, peracetic acid and tert-butyl hydroperoxide.
3. The low-concentration hydrofluoric acid composite etching liquid according to claim 1, The etching accelerator comprises any one or more of ammonium fluoride, ammonium bifluoride and triethanolamine hydrofluoric acid salt.
4. The low-concentration hydrofluoric acid composite etching liquid according to claim 1, The interface modification and mass transfer accelerator comprises any one or a combination of a plurality of acetylene glycol surfactants, polyether modified silicone oil and sodium dodecyl diphenyl ether disulfonate.
5. The low-concentration hydrofluoric acid composite etching liquid according to claim 1, The product control and stabilizing agent comprises any one or more of citric acid, gluconic acid, hydroxyethyl ethylenediamine triacetic acid, sodium hexametaphosphate, ammonium dihydrogen phosphate, boric acid-borax systems, sodium stannate, oxalic acid, tartaric acid, malic acid, sodium tripolyphosphate, sodium hexametaphosphate, sodium polyacrylate, and polymaleic anhydride.
6. The low-concentration hydrofluoric acid composite etching liquid according to claim 1, The equipment compatible corrosion inhibitor comprises any one or a combination of a plurality of benzotriazole, methyl benzotriazole, sodium molybdate, sodium tungstate and hydroxyethylidene diphosphonic acid.
7. A method for preparing a low-concentration hydrofluoric acid composite etching solution according to any one of claims 1 to 6, comprising: adding deionized water and etching additives into a reaction container, fully stirring until the mixture is uniform, slowly adding hydrofluoric acid, and fixing the volume to obtain the low-concentration hydrofluoric acid composite etching liquid.
8. The low-concentration hydrofluoric acid etching process is characterized by comprising the following steps of: S1, injecting the low-concentration hydrofluoric acid composite etching liquid according to any one of claims 1 to 6 into an etching acid tank of chain equipment; S2, transmitting the silicon wafer with the front surface structure and TOPCon back surface field to an etching acid tank to submerge the back surface of the silicon wafer; And S3, conveying the immersed silicon wafer to a multi-stage countercurrent rinsing tank and a drying unit for treatment, and completing etching.
9. The low concentration hydrofluoric acid etching process of claim 8, The temperature of the liquid in the step S1 is maintained to be 25-35 ℃; and the immersion time of the silicon wafer in the step S2 is 60-420S.
10. A perovskite cell comprising a silicon wafer treated by the low concentration hydrofluoric acid etching process of claim 8.

Description

Low-concentration hydrofluoric acid composite etching liquid and preparation method and etching process thereof Technical Field The invention belongs to the technical field of photovoltaic wet etching, and particularly relates to a low-concentration hydrofluoric acid composite etching solution, a preparation method thereof and an etching process. Background TOPCon/perovskite stacked cells are a key direction leading to the next generation of photovoltaic technology, and during the preparation process, the perovskite top cell and the silicon-based TOPCon bottom cell need to be integrated optically and electrically, therefore, a silicon nitride mask layer on the back of a traditional TOPCon cell needs to be removed to expose a polysilicon layer below, so that a charge transport layer of the perovskite cell can form high-quality and high-efficiency electrical interconnection with a TOPCon-structured doped polysilicon layer. At present, high-concentration hydrofluoric acid is widely adopted in chain equipment for carrying out wet etching process in industrialized silicon nitride removal, but the method brings serious challenges in that firstly, the chain equipment has special requirements on the etching process that the etching rate must be fast enough to match the production line beat, the etching uniformity must be extremely high to prevent fragments and yield loss, and the process must be stable and controllable. And secondly, uncontrollable damage to the passivation and transmission layer, namely, high-concentration HF can cause etching risk to the underlying Poly silicon and the ultrathin tunneling oxide layer with the thickness of 1-2 nanometers while rapidly removing the silicon nitride, and the passivation performance of the TOPCon structure is damaged, so that the open-circuit voltage of the silicon bottom cell is greatly reduced. And moreover, the safety and the efficiency are contradicted, namely the damage to the tunneling layer can be reduced by the low-concentration HF, but the etching rate is too slow, the requirements of industrial production on efficiency and uniformity cannot be met, and the risk of incomplete etching is high. And high concentration HF brings high volatility acid mist safety protection, waste gas treatment and environment to form threat. High concentration means high HF unit consumption, heavy waste liquid treatment load, and increased production cost and environmental burden. Therefore, although the above problem can be alleviated by directly using low-concentration HF in the chain equipment, the etching rate is too slow to meet the production line beat (usually the whole process is required to be completed in a few minutes), and a large amount of waste products are easily caused by uneven etching or residues. The acid reducing additive adopted in the prior art is concentrated on fluoride buffering and complexing action, but the fundamental principle is still dependent on the concentration of HF, the order of magnitude of etching rate cannot be improved under low concentration, and the dynamic bottleneck problem of etching silicon nitride by using low concentration HF cannot be fundamentally solved. It should be noted that the above information disclosed in this background section is only for understanding the background of the inventive concept and therefore the above description is not to be construed as constituting prior art information. Disclosure of Invention The embodiment of the disclosure at least provides a low-concentration hydrofluoric acid composite etching liquid, a preparation method thereof and an etching process. According to the first aspect, the embodiment of the disclosure provides a low-concentration hydrofluoric acid composite etching liquid, which comprises, by mass, 5% -10% of hydrofluoric acid, 2% -5% of an etching additive and the balance of water, wherein the etching additive comprises, by mass, 8% -25% of a strong oxidant, 2% -5% of an etching accelerator, 0.5% -2% of an interface modification and mass transfer accelerator, 0.1% -3% of a product control and stabilizer, 0.1% -2% of a device compatible corrosion inhibitor and the balance of water, the strong oxidant is used for oxidizing silicon nitride to form a silicon oxynitride transition layer, the etching accelerator is used for providing HF molecules and HF 2- ions, and the product control and stabilizer is used for complexing SiF 62- ions generated by etching. In an alternative embodiment, the strong oxidizing agent comprises any one or more of hydrogen peroxide, potassium peroxymonosulfate, ammonium persulfate, sodium chlorate, potassium iodate, peracetic acid, t-butyl hydroperoxide. In an alternative embodiment, the etch promoter comprises any one or a combination of ammonium fluoride, ammonium bifluoride, triethanolamine hydrofluoric acid salt. In an alternative embodiment, the interface modification and mass transfer promoter comprises any one or more of an acetylenic diol surfactant, a p