Challenges in Slicing Large Diameter Silicon Wafers Using Slurry Wiresaw

This paper describes the challenges present in slicing large diameter silicon ingots using the multiple slurry wiresaw or commonly known as the wiresaw. The wiresaw uses a web of wires moving at a fast speed with a suitable abrasive suspended in a media dropped over the wires. The silicon ingot is lowered on to the web from top down and the cutting action is achieved by the abrasive particles rolling and indenting on the ingot thus removing material. While the cutting mechanism itself is fairly well understood, to achieve the similar surface finish and quality compared to smaller diameter ingots, the cutting parameters of large diameter ingots is not so straightforward. There are many parameters which have to be taken into account which normally would have been neglected or thought insignificant in the case of smaller ingots. We will discuss the various parameters that are affected while slicing small diameter ingots (typically 100 mm) as well as larger diameters (typically 300 mm). Results of experimental tests using commercial wiresaws for slicing these ingots are given to show the effect of wire speed, table speed, the nature of the slurry and other parameters. We also will show how such effects can be described in an analytical fashion by models that have been developed to demonstrate such cutting mechanism.