The analysis of complex samples by spectroscopic ellipsometry

Abstract

Spectroscopic ellipsometry provides non-contact, non-destructive characterization with multi-layer composition-, strain-, and thickness-sensitivity. Modern computer technology readily permits the extensive computer analysis required to extract the relevant parameters for multi-layer samples. The accuracy of these inferred parameters is reduced by the interactions between various required parameters. This work discusses how rather complex samples can be fully analyzed. In terms of complexity of samples to be analyzed, current results suggest at least six, and possibly eight, independent materials parameters (such as thickness or Al mole fraction) can be extracted from a single measurement and analysis. Accuracies of order 0.1%-1% are readily achieved for several of these parameters. Furthermore, the application of numerical derivative techniques to the experimental data permits analysis of critical point structures. Linewidths can provide a direct monitor of doping levels for a material, whereas energy position is a function of strain and composition. Using the multi-layer analysis routines to uniquely determine composition permits the derivative structures to establish strain effects. © 1989.