TOTAL-REFLECTION X-RAY-FLUORESCENCE ANALYSIS OF PLANARIZED SEMICONDUCTOR PRODUCT WAFERS

The use and effectiveness of total reflection x-ray fluorescence (TXRF ) have been widely reported. The application of this technique in semi conductor fabrication has become popular and several instrument vendor s now make equipment optimized for this particular purpose. Because sa mple surfaces must be optically flat in order to achieve the total ref lectance condition, the majority of the work in investigating semicond uctor processing is performed on monitor wafers. The use of TXRF for i n-line process control, therefore, has been limited to silicon or diel ectric film substrates, either on the surface or the backside of the w afer. This article details the use of TXRF analysis for monitoring the contamination present on production-wafer surfaces, after planarizati on techniques have been used. The wafer surfaces at several of these p lanarization steps meet the criteria for the application of the TXRF t echnique using the normal operating conditions of the TXRF instrument. This technique can be used as process-monitoring tool to study wafer surfaces for particular contaminants that affect wafer yield. TXRF is being used on IBM's state-of-the-art DRAM and logic circuits. (C) 1996 American Vacuum Society.