The Effect of Chemical Composition on Porous Etching for Epi and Lift-off Silicon Wafer Process

• Main Authors: Peng-Wei Chen, 陳芃瑋
• Other Authors: Han-Wen Liu
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/15199453170982177848

碩士 === 國立中興大學 === 光電工程研究所 === 105 === The cost of silicon wafer fabrication is about 50% of the total cost of silicon based photovoltaic module, and the solar cell manufacture process and module costs account for another 50%. In conventional silicon photovoltaic value chain, it will waste lots of silicon. Slicing is the most wasteful part. The kerf-loss will waste 34% of silicon. Epi and lift-off processes have developed to replace slicing one. This study focuses on the composition and concentration of etching solutions and finds out the best etching recipe for the p-type and n-type silicon. Epi and lift-off processes can create single crystalline silicon wafers without kerf-loss. There are three basic steps in epi and lift-off process: porous layer formation, epitaxial growth, and exfoliation. The porous layer is fabricated by electrochemical etching in hydrofluoric acid solution. The ethanol is usually added into the etching solution to enhance the contact between substrate surface and solution. Because the ethanol is volatile, the ethanol content in the etching solution is changeable to destroy the stability of the solution composition in this study. A relative solvent, isopropanol, is also adopted to replace the ethanol to reduce evaporation rate of the solutions. In this study, we focus on three points: the composition of the etching solutions, changing the concentration of the etching solutions and investigating the etching characteristics of p-type and n-type silicon substrate, individually.