Application of Low Angle Beveling for Thin Film Thickness Measurement by SEM or AES

Abstract

The feasibility of measuring the thickness of very thin films (<1000Å) by using a low angle beveling technique in conjunction with a scanning electron microscope (SEM) or an Auger electron spectroscope (AES) has been demonstrated. The thin film thickness has been magnified in two steps, 200 times with low angle beveling, and an additional 5000 times with the SEM or AES. The accuracies of measurements performed on two films having thicknesses of 740 and 194Å were found to be 4.2% and 13.4%, respectively, when compared to ellipsometric measurements. This technique has also been used on MOS gate oxide and Si‐Cr thin film resistor samples. With better control of the variables involved, it is reasonable to expect that films on the order of 20Å could be measured.