Generation of pulsed direct-current plasma above 100 torr for large area diamond deposition

Abstract

A high-temperature, large-size plasma was successfully generated at a pressure above 100 torr using a pulsed direct current (DC) electric power for the application of wafer-scale diamond thick film growth. A diode type electrode configuration was used, with a Mo disk of 13 cm in diameter as a cathode and a W disk of 10 cm in diameter as a substrate. By adjusting the pulse condition and maintaining the cathode temperature between 1000 degreesC and 1100 degreesC, the arc between the electrodes was suppressed completely and the plasma was maintained very stably for over 100 h. Above and below this cathode temperature range, solid carbon was deposited on the cathode, which induced either the arc or non-uniformity of plasma state. A diamond wafer with a thickness up to I mm was successfully grown using this plasma of methane and hydrogen mixed gas. The plasma characteristics were analyzed using an optical emission spectroscopy. (C) 2001 Elsevier Science B.V. All rights reserved.