Oxide process monitoring for process deviations and contamination is essential for achieving high performance and yield in advanced integrated circuits. Moreover, monitoring techniques must be able to frequently measure actual production-critical films to minimize the cost of monitoring and to minimize the product at risk. A methodology and experimental results for qualifying a surface charge analyzer (SCA) for in-line monitoring of ultrathin oxides (less than 30 angstroms) are presented. The SCA provides rapid measurements of total oxide charge, density of interface traps, minority carrier recombination lifetime and doping concentration with sensitivities that are independent of oxide thickness. Process deviations in anneal, pre-clean, oxidation recipe and wafer substrate, were intentionally introduced on sample wafers. All wafers with intentional process deviations were detected by the SCA. Process tolerance and SCA precision were also estimated. The SCA meets the requirements for an in-line process monitor by performing rapid, repeatable and cost effective measurements on ultrathin oxide production recipes.
