Practical Limitations in Depth Profiling of Low Energy Implants into Amorphised and Crystalline Silicon

As lateral dimensions in semiconductor devices shrink, so must the depth dimensions, requiring accurate analysis of impurity concentrations with ever increasing depth resolution [1–2]. Measurement of impurity dopant profiles by secondary ion mass spectrometry is complicated by the presence of physical and instrumental effects which result in measured secondary ion intensity distributions with depth which deviate from the original concentration variation with depth [3–5]. These effects are assessed, particularly in the case of some instrumental effects, using low energy ion implants.