Beam-induced wafering technology for kerf-free thin PV manufacturing

A novel ion beam-induced cleaving process for slicing c-Si wafers ranging in thickness from 20¿m to 150¿m with near zero kerf-loss and markedly low overall cost has been developed and demonstrated to be capable of large-area thin PV substrate manufacturing. This paper introduces this new wafering technology, called the Direct Film Transfer (DFT) process, and describes its practical utilization to produce wafers spanning from ultra thin foils to free-standing substitute wafers in high-volume silicon PV cell manufacturing. In addition to the 50¿m thick wafering capability, recent 20¿m and 150¿m wafering results complete the extension and applicability of the DFT process. The material characteristics and preliminary solar cell efficiencies of the DFT wafers are presented. With the advent of this new wafering technology, development work and production use of ultra thin CZ silicon based solar cells are expected to accelerate.