Study of the background sources in the trace analysis of carbon using secondary ion mass spectrometry

Abstract

The background sources have been studied in the trace analysis of carbon (and oxygen) using secondary ion mass spectrometry. In particular, the physical mechanism limiting the detection limit of carbon (and oxygen) in GaAs was investigated. It was speculated that the three kinds of background sources could be discriminated using the simple method that we called the background source analysis (BGA) method. It was found that memory effect was the most harmful barrier to lowering the detection limit of carbon impurity in GaAs at the conventional pressure (10−9 Torr). On the basis of the quantitative BGA method, the best condition of the measurement in the trace analysis of carbon in GaAs was estimated to be 50 nA for the primary beam current at the raster-scanned area of 30×30 μm2.