REAL-TIME PROCESS SENSING AND METROLOGY IN AMORPHOUS AND SELECTIVE-AREA SILICON PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION USING IN-SITU MASS-SPECTROMETRY

We have used mass spectroscopy to observe and analyze, in real-time, g as phase reactants and product species in plasma enhanced chemical vap or deposition (PECVD) of silicon. We describe a doubly differentially pumped mass spectrometry system to sample the exhaust stream of a larg e area plasma CVD reactor operating at 0.4-1.5 Torr. We show real-time quantitative analysis of silane consumption and hydrogen production f or deposition of hydrogenated amorphous silicon and for pulsed-gas sel ective area silicon deposition. The ability of mass spectrometry to ob serve process faults in real time is also demonstrated. Mass spectrosc opy is a useful nonintrusive process-state sensor for real-time metrol ogy of plasma deposition, for example, to quantify gas phase species, and to characterize reactions occurring on the substrate surface. Base d on our results, we discuss I potential advanced manufacturing applic ations of real-time mass spectrometry in amorphous silicon and selecti ve area silicon plasma deposition, including indirect wafer-state sens ing, fault analysis and classification, and run-to-run and real-time p rocess control. (C) 1997 American Vacuum Society.