Optical evaluation of ingot fixity in semiconductor wafer slicing

Abstract

The fixity of an ingot may greatly affect the quality of wafers produced during a wire saw process and improved mechanical clamping is a means for improving ingot fixity. Here, an optical technique that is based on laser beam deflection is described. The technique was demonstrated on ingot assemblies subjected to impulse loads within a prescribed range using an original and improved clamping system. The technique revealed that the ingot assembly had lower degrees of mean displacement and standard displacement deviation under the improved clamping system. The data on warp obtained from the actual production of wafers corroborates this finding. The technique described is an effective method of quantitatively evaluating the fixity of ingots in a wafer wire saw process. © 2004 Elsevier Ltd. All rights reserved.