Depth profiles of As and Sb angle-implanted trenches measured by secondary ion mass spectrometry

Abstract

Depth profiles of As and Sb angle-implanted trench pilot wafers and a fully processed 16 MB dynamic random access memory chip have been measured using secondary ion mass spectrometry (SIMS) to determine the doping level in the walls of the trench capacitors. As and Sb exhibit similar behavior throughout the implant and analysis process. The SIMS data correlates well with scanning electron microscopy cross sections of the trenches and simple geometrical arguments as well as with capacitance-voltage measurements of processed wafers. The presence of a gate dielectric does not appear to interfere with SIMS analysis of trench wall doping, and this technique is therefore applicable as a post-process monitor of doping distribution.