Process Modeling of a Wire Saw Operation

Abstract

Multicrystalline (MC) silicon solar cells are manufactured from bread-loaf sized ingots of solar-grade silicon by means of a multi-wire saw. In a typical wire saw system, MC ingots are sliced with an area of 100x100 mm2 and the latest wire saw systems can achieve thicknesses down to 300 microns. What makes this a challenging simulation problem is the wide range of timescales that characterize the overall cutting process. The slowest dynamics are associated with the evolution of the cut, which is described by a spatially dependent differential equation in time and in which the cutting rate is modeled much in the same manner as the Chemical Mechanical Planarization (CMP) process. The goal is to understand the physical mechanisms that limit how thin the wafers can be cut and to determine the sensitivity of cutting time and cutting rate based on process parameters.