Use of new technology for enhanced detection of crystalline defects on silicon wafers

Abstract

Detecting and quantifying contaminants and crystalline defects on micro-grade silicon wafers is extremely important to ensure the IC device yield. Although Laser Scanning Surface Inspection Systems are widely used for contaminant inspection, visual inspection continues to be used in silicon wafer manufacturing facilities because conventional particle scanners are not capable of identifying and quantifying a variety of material defects such as Epi spikes, ESF, pits, and sliplines. This work investigates a new technique to detect these material defects by combining information from two independent phenomena, light scattering and reflecting. The optical system to study this technique consists of a conventional particle scanner to detect and quantify light scattering events from contaminants on the wafer surface and a Reconvergent specular Detection apparatus. This apparatus is capable of imaging material defects by measuring attenuation of the light beam intensity reflected from the water surface due to diffraction, absorption, and distortion. Epi mounds voids, slip dislocations, and some other common defect features and contamination on silicon wafers are studied using this equipment. The results are confirmed by that of microscope or AFM. This technology provides the solution to the wafer manufacturing industry for full automated wafer inspection and defect classification.