Application of diode laser spectroscopy for moisture contamination measurement in semiconductor processing

The applications of tunable diode laser absorption spectroscopy (TDLAS) to a variety of semiconductor process environments, including RTP, CVD and etch, are discussed. TDLAS has been demonstrated to be compatible with aggressive gases such as HCl, NH/sub 3/, SiH/sub 2/Cl/sub 2/, etc. and with strongly depositing atmospheres as in Si/sub 3/N/sub 4/ LPCVD. In addition, it has been shown to be capable of trace moisture measurements to 50 ppb in pure NH/sub 3/ and to 10 ppb in a variety of corrosive gases including HCl. These applications are discussed as are the key differences in approach required for in situ and for high-purity gas measurement.