Gate oxide properties investigated by TOF-SIMS profiles on CMOS devices

Dynamic secondary ion mass spectrometry (SIMS) is commonly considered an important analytical technique to study the materials used for microelectronics. Direct analyses on electrically tested structures are hard to perform because of strict requirements on raster size and because of poor depth resolution on multi-layer stacks. Time of flight SIMS has been recently applied to this field and developed to perform depth profiles with competitive features. The aim of this work is to show that TOF-SIMS can be directly used to characterize finished devices. By measuring n-MOS capacitors of full processed wafers (raster size up to 12 μm×12 μm), we studied the Cl contamination introduced by chemical vapor deposition of WSi2. The comparison between depth profiles and electrical data explained the observed gate oxide behavior.