CHARACTERIZATION OF SUBSTRATE-TEMPERATURE AND DAMAGE IN DIAMOND GROWTH PLASMAS BY MULTICHANNEL SPECTROELLIPSOMETRY

The growth of diamond thin films in enhanced chemical vapor deposition (CVD) processes requires high substrate temperatures (400-1000 degree s C) and gas pressures (1 Torr to 1 atm), as well as high-power excita tion of the gas source (e.g., 1 kW microwave plasma). Thus determining the substrate temperature in this severe environment is a challenge. The issue is a critical one since substrate temperature is a key param eter for understanding and optimizing diamond film growth. We have dev eloped and utilized methods for precise (similar to+/-5 degrees C) Si substrate temperature calibration based on rapid-scanning spectroscopi c ellipsometry. In this approach the E(1) Critical point energy in Si is used to deduce the temperature of the top similar to 200 Angstrom o f the substrate. In addition, the broadening parameter associated with the critical point transitions can provide information on near-surfac e plasma damage. As an application of the temperature calibration, we have measured the kinetics of diamond film growth by the microwave pla sma-enhanced CVD process. (C) 1995 American Vacuum Society.