Carrier Illumination as a tool to probe implant dose and electrical activation

Abstract

The Carrier Illumination™ (CI) method is an optical technique for non‐destructive in‐line monitoring of post‐anneal junction depth, pre‐anneal pre‐amorphisation implant (PAI) depth, and dose. This work describes the sensitivity of the CI‐signal to the as‐implant dose and demonstrates that a universal response function can be derived for doses below the amorphisation limit. For the implants where the elements/doses cause amorphisation, the CI‐signal reflects directly the thickness of the amorphous depth. In the case of annealed structures, it is shown that CI provides important information on the electrical activation of the dopant. This is illustrated by the analysis of CVD‐layers subsequently annealed and of junction profiles produced by laser annealing. In both cases nearly identical dopant profiles are observed with secondary ion mass spectrometry while the electrical activation as derived from sheet resistance measurements is very different. This very different activation level is clearly reflected in the CI‐signal. This indicates that the CI‐signal is not solely related to the junction depth and the profile abruptness but also to the electrical activation of the dopants.