Plasma diagnostic measurements of argon-hydrogen-methane dischargesused for ultra-nanocrystalline diamond deposition in a microwave CVDsystem

摘要

Summary form only given, as follows. Argon-methane andargon-methane-hydrogen discharges used in a microwave CVD system for thedeposition of diamond films are investigated in this study. Thesedischarges have been used to produce small grain size diamond films,also known has ultra-nanocrystalline diamond. To further understand theplasma deposition process experimental measurements of the dischargeshave been undertaken. Specifically, the objective of this study is todetermine the relationship of the deposition results versus plasmaspecies concentrations and temperatures. The deposition discharges beingstudied are at pressures of 80-160 Torr with 0-3% methane and 0-10%hydrogen in an argon discharge. The plasma discharges studied areexcited using a 17.8 cm diameter microwave resonant cavity reactor. Thedischarges are excited using 2.45 GHz microwave power in a dischargechamber with 12.5 cm diameter. Experimental characterizations includeOES measurements of selected atomic hydrogen, C₂, and CHemission lines, and OES measurements of gas temperature in thedischarge. Changes in the input gas composition are observed to producesubstantial variations in these OES measurements. The measurements areconducted as functions of the discharge's quartz wall temperature(100-200 C) and the substrate temperature (400-900 C). The dischargeexperimental measurement results are also correlated with the propertiesof the diamond films deposited