Patent ID: 6191849
Filing Date: 2001-02-20
Classification: G01N

Abstract:
A wafer inspecting apparatus for obliquely irradiating a wafer with rays and detecting rays which are scattered from the wafer, and are caused by foreign matter adhering to the surface of the wafer and by internal defects in the wafer comprising:a first scattered ray detecting system for detecting the scattered rays from the wafer; anda second scattered ray detecting system for detecting the scattered rays from the wafer;wherein said first scattered ray detecting system is disposed in a first direction where the intensity of scattered rays which are scattered from foreign matter adhering on the surface of the wafer and detected by said first scattered ray inspecting system is larger than the intensity of scattered rays which are scattered from the foreign matter and detected by said second scattered ray inspecting system, and the intensity of scattered rays which are scattered from an internal defect of the wafer and detected by said first scattered ray inspecting system is smaller than the intensity of scattered rays which are scattered from the internal defect and detected by said second scattered ray inspecting system;said second scattered ray inspecting system is disposed in a second direction where the intensity of scattered rays which are scattered from a foreign matter adhering on the surface of the wafer and detected by said second scattered ray inspecting system is smaller than the intensity of scattered rays which are scattered from the foreign matter and detected by said first scattered ray inspecting system, and the intensity of scattered rays which are scattered from an internal defect of the wafer and detected by said second scattered ray inspecting system is larger than the intensity of scattered rays which are scattered from the internal defect and detected by said first scattered ray inspecting system and;a comparator comparing the intensity of the scattered rays detected by said first scattered ray inspecting system with the intensity of the scattered rays detected by said second scattered ray inspecting system to distinguish the foreign matter and the internal defects from each other.