| dc.description.abstract | During solar cell processing, wafer cutting is an import procedure for yield, nowadays wire saw is the main cutting process, it has multi-wire with high efficiency, but has produced stress while cutting, it may let wafer break, and the particle can not be used fully, the particle will contaminate environment. Therefore, wire electrical discharge machining was investigated to improve wire saw processing, but most of research of material is single-crystal silicon, the poly-crystal investigate is few, because poly-crystal silicon with higher resistance, it is hard to machine for wire electrical discharge machining.
This research is mainly divided into two major parts, the first part adopts pure water as dielectric in order to know the possibly of machinine, and investigate the influence of characteristic of each processing parameter The second part is according to the previous part results to improve the machining efficiency, we add sodium pyrophosphate powder in pure water, we want use phosphorous’ high electric conductivity to improve the efficiency, and use high temperature let phosphorous doping into wafer’s surface by wire electrical discharge machining to achieve p-n junction. Comparing with conventional solar cell processing, can save ion implantation, let the processing simply.
Form the experiment results, using sodium pyrophosphate as dielectric can get fast feed ratio is 0.528 mm per second while pulse on time is 6.5μs, ampere is 10A, and comparing in the same parameter, the feed ratio increase 2.4 magnification, and improve surface roughness by electrolysis at high temperature, as previous results corroborating that dielectric with phosphorous can improve machining efficiency and dopping phosphorous into surface simultaneously.
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