Plasma diagnostic measurements of argon-hydrogen-methane discharges used for ultra-nanocrystalline diamond deposition in a microwave CVD system

Summary form only given, as follows. Argon-methane and argon-methane-hydrogen discharges used in a microwave CVD system for the deposition of diamond films are investigated in this study. These discharges have been used to produce small grain size diamond films, also known has ultra-nanocrystalline diamond. To further understand the plasma deposition process experimental measurements of the discharges have been undertaken. Specifically, the objective of this study is to determine the relationship of the deposition results versus plasma species concentrations and temperatures. The deposition discharges being studied are at pressures of 80-160 Torr with 0-3% methane and 0-10% hydrogen in an argon discharge. The plasma discharges studied are excited using a 17.8 cm diameter microwave resonant cavity reactor. The discharges are excited using 2.45 GHz microwave power in a discharge chamber with 12.5 cm diameter. Experimental characterizations include OES measurements of selected atomic hydrogen, C/sub 2/, and CH emission lines, and OES measurements of gas temperature in the discharge. Changes in the input gas composition are observed to produce substantial variations in these OES measurements. The measurements are conducted as functions of the discharge's quartz wall temperature (100-200 C) and the substrate temperature (400-900 C). The discharge experimental measurement results are also correlated with the properties of the diamond films deposited.