ウエハ上微粒子およびウエハ内結晶空洞（ＣＯＰ）からの散乱光の実験的解析

Abstract

In this study, an experiment to detect the small particles adhering to a wafer and the crystal originated particles (COPs) existing in the wafer, whose diameters are approximately 0.1μm, is carried out successfully. An experiment to separate COPs from detected particles is also carried out. Both particles and COPs are detected when an Ar-ion laser is illuminated perpendicularly downward onto the wafer, and the obliquely scattered light is detected using a photomultiplier tube No. 1. Only particles are detected when a YAG laser is illuminated obliquely with an incident angle of 77° and the light scattered perpendicularly upward is detected using a photomultiplier tube No. 2. On the basis of the two detected signals, the particles and COPs can be recognized independently. The experiment was conducted using two types of wafers. One is a wafer made by a Czochralski (CZ) method, which is known as a wafer with COPs, and the other is a wafer made by a floating zone (FZ) method, which is known as a non-COP wafer. COPs are detected on the CZ wafer but not on the FZ wafer. On the basis of this experimental result, it is experimentally verified that COPs can be detected by this detection method.