Characterization of recrystallized depth and dopant distribution in laser recovery of grinding damage in single-crystal silicon

Abstract

A nanosecond pulsed Nd:YAG laser was irradiated on a boron-doped single-crystal silicon wafer with a diamond grinding finish to recover the grinding-induced subsurface damage. In order to visualize and measure the depth of the laser melted/recrystallized layer, small-angle beveled polishing was performed in pure water followed by KOH etching. It enabled the direct observation of the recrystallized region using a differential interference microscope and the measurement of its depth using a white light interferometer. Crystallinity analysis of the recrystallized region was carried out by using laser micro-Raman spectroscopy, and the dopant concentration profile was characterized by using radio frequency glow discharge optical emission spectrometry (rf-GD-OES). The results showed that the crystallinity and boron distribution in the recrystallized region changed after laser recovery. The dopant concentration becomes higher at the boundary of the recrystallized region and the bulk. This study demonstrates the possibility of boron concentration control by using suitable laser parameters.