Quantitative measurement of two-dimensional dopant profile by cross-sectional scanning capacitance microscopy

Abstract

Quantitative two-dimensional dopant profiling of a gatelike structure is achieved by scanning capacitance microscopy (SCM). A processed silicon wafer is sectioned then polished such that a cross section is made through a gatelike structure. This structure consists of two n+ doped regions separated by a lighter doped n region. The two-dimensional SCM data are converted to dopant density through a physical model of the SCM–silicon interaction. Improvements to the physical model and SCM data to dopant profile algorithm are discussed. Advances in sample preparation are described. Adjustment of the conversion model parameters allows for fitting of the SCM dopant profile to a vertical secondary-ion-mass-spectroscopy profile. The accuracy of this fit is better than 20%. This fit also gives strong evidence that the full two-dimensional profile is truly quantitative.