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

A high-temperature, large-size plasma was successfully generated at a press ure above 100 torr using a pulsed direct current (DC) electric power for th e application of wafer-scale diamond thick film growth. A diode type electr ode configuration was used, with a Mo disk of 13 cm in diameter as a cathod e 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 an d the plasma was maintained very stably for over 100 h. Above and below thi s cathode temperature range, solid carbon was deposited on the cathode, whi ch induced either the arc or non-uniformity of plasma state. A diamond wafe r with a thickness up to I mm was successfully grown using this plasma of m ethane and hydrogen mixed gas. The plasma characteristics were analyzed usi ng an optical emission spectroscopy. (C) 2001 Elsevier Science B.V. All rig hts reserved.