Paper AS-MoM5
The Bulk Ratio Method for Determining Surface Enhancement Using Auger Analysis

Monday, October 15, 2007, 9:20 am, Room 610

Enhanced surface layers on stainless steel are engineered to provide improved corrosion resistance and reduced surface reactivity. Stainless steel can be electropolished and chemically treated in such a way that the surface finish is improved while enhancing the chromium levels near the surface. This modification is thought to increase corrosion protection and produce less gas stream particulates for semiconductor applications. The surface analysis techniques of x-ray photoelectron (XPS) and Auger electron spectroscopy (AES) have been used for decades to characterize the effects of these treatments by observing the near surface chemistry. International standards and practices (Sematech, ASTM F-1402-92 and SEMI 2335b), for AES and others for XPS, have been written to guide the analyst on how to calibrate their instruments, as well as collect and reduce the data. The test results most often examined are the oxide depth and maximum Cr to Fe ratio. Improved standard practices are necessary to reduce the variability that is seen between instruments and between laboratories for measuring the ratios. The variability likely stems from the use of sensitivity factors that are not representative of the host instrument and the improper selection of standards. The Bulk Ratio Method is a new approach which provides the same numerical value of chromium enhancement from data collected and reduced using either relative intensities or sensitivity factors. The Bulk Ratio can be easily calculated from historical data collected on different instruments and laboratories.