Characterization and detection of metals in silicon and germanium

Abstract

This chapter outlines a large variety of analytical techniques for the detection of metal contamination on and in silicon or germanium wafers. For each of the techniques, the basic principle will be outlined, their weaknesses and strengths. Special focus will be on methods which can be applied for in-line contamination monitoring, with wafer mapping capabilities. This is important both for CMOS and PV applications. Distinction will be made between chemical (providing a chemical fingerprint of the TM), structural (allowing to image precipitated phases) and electrical analysis methods. For the latter, lifetime-based techniques are the most popular, providing a more direct link with device and circuit operation. Deep-Level Transient Spectroscopy (DLTS), on the other hand, is since its introduction the reference technique for the study of electrically active defects in semiconductors. In order to identify unknown metal contamination, a combination of different techniques has to be applied, which may be different depending of the contaminant under suspicion. The chapter is concluded with a general strategy for performing this challenging task.