Sources of surface contamination affecting electrical characteristics of semiconductors

Abstract

Surface cleanliness has become an extremely critical concern in the manufacture of semiconductor products. The parts per 109 levels of contaminants in a chemical cleaning solution can drastically affect electrical parameters. Using a buried surface layer technique in conjunction with secondary ion mass spectrometry, it is shown that contaminants that are present at low levels in solution can concentrate on the surface of wafers. When the contaminant is boron, inversion layer problems can occur, while aluminum contamination can affect threshold voltage readings on dual dielectric films. Stainless-steel contamination is deadly for leakage concerns. The sources of these and other contaminants must be located and monitored closely.