LARGE-SIZE PLASMA GENERATION USING MULTICATHODE DIRECT-CURRENT GEOMETRY FOR DIAMOND DEPOSITION

The deposition area of diamond film is increased by applying a geometr y of multiple cathodes and a single anode in direct current (dc) plasm a assisted chemical vapor deposition (PACVD). Each cathode is made of Ta and connected independently to its own de power supply. The operati ng pressure is 1.3 x 10(4) Pa (100 Torr), and methane-hydrogen mixed g as is used as reaction gas. The voltage and the current applied to eac h cathode are 650 V and 4 A, respectively. The transition from a diffu se glow to an are is prevented by maintaining cathode temperatures abo ve 2000 degrees C, which inhibits carbon deposition on the cathodes, T ranslucent diamond film of 3 in, diameter, thicker than 200 mu m, is g rown using seven cathodes with 3% CH4-H-2 mixed gas for 110 h. The dep osition area can be increased further by increasing the number of cath odes.