Determination of organic contaminants on wafer surfaces and in process chemicals using capillary electrophoresis

Increasing the integration density in microelectronics demands a continuous reduction of both metallic and non-metallic contaminants on the surface of silicon wafer. The origin and mechanism of metallic contamination and the principle of its reduction are well understood. However, the silicon wafer is also exposed to detrimental organic substances from various sources in the process environment, such as organic vapors of cleaning solutions, in clean room air, plastic shippers and lithography. At present, thermodesorption gas chromatography coupled to mass spectrometry (TD-GC-MS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) are used for monitoring organic contamination. Capillary electrophoresis (CE) as a complementary micro-analytical technique offers some unique features for the inspection of integral wafer surfaces, We give an overview of the possibilities CE applications offer for the investigation of organic. CE methods as applied in R&D are presented for the determination of carboxylic acid, surfactants and degradation products of plastics on wafer surfaces as well as fingerprint contaminations of surfactants used in different cleaning solutions.