Influences of hard inclusions on processing stress in diamond multi-wire sawing multi-crystalline silicon

Abstract

There are SiC and Si3N4 hard inclusions in photovoltaic mc-Si, which will lead to stress concentration in the sawing process and reduce the fracture strength of as-sawn wafers. In this paper, a finite element model of diamond multi-wire sawing mc-Si with hard inclusions is established. The influence of the type, size, location of the hard inclusions, the coupling effect between adjacent inclusions and the sawing process parameters on the thermal mechanical coupling sawing stress and stress concentration factor was analyzed. The research results show that the greater the thermal expansion coefficient of the inclusions, the greater the stress concentration. The larger the size of the hard inclusions, the greater the sawing stress. The inclusions distributed at the saw wire outlet and the center of the saw kerf will produce greater sawing stress. The smaller the distance between adjacent inclusions, the greater the coupling sawing stress. Increase the wire speed and the workpiece feed speed, and the sawing stress caused by the influence of inclusions increases. The research results of this paper provide a theoretical reference for understanding the influence of hard inclusions inside mc-Si on the sawing stress and optimizing process parameters.