Plasma etching is one of the most important methods used for patterning of electronic materials and for fabrication of VLSI circuts. Critical to the understanding and further development of processes such as plasma etching is the availability of diagnostic tools that permit study and eventual monitoring or control of the process. This program will study the development of such instrumentation based on lead-salt diode laser absorption spectroscopy to monitor important gas phase species in the etching process. The major objective of the Phase I program is the investigation of sensitive new measurement techniques using diode lasers and the demonstration of these techniques to monitoring applications in plasma etching reactors. In particular, high frequency optical heterodyne techniques will be studied that should permit a significant simplification in the optical design of the system. The technique will be demonstrated by measurement of boron trichloride and its important decompositon products in a dc discharge. Results of the Phase I study will provide the required design information for the Phase II development of a compact instrument for on-line monitoring of plasma etching, plasma deposition, chemical vapor deposition, or other chemical process.
