The effects of substrate rotation on thermal plasma chemical vapor deposition of diamond

The effects of substrate rotation on the chemical vapor deposition (CVD) of diamond is investigated utilizing a Triple Torch Plasma Reactor (TTPR) act ivation source. Diamond deposition experiments are conducted with an Ar-H-2 -CH4 plasma gas mixture at reduced pressures. Substrate rotation is achieve d by means of a variable speed DC gear motor used to rotate the substrate s haft. Rotation of the substrate during deposition, as well as rotation and offsetting the substrate axis from the converging plasmajet axis, is found to increase the average mass deposition rate as well as the average area of deposit when compared to a stationary substrate. Film and crystal size uni formity of the deposit are found to be enhanced, and deposit roughness decr eased by rotating, and rotating plus offsetting the substrate when compared to a stationary substrate. Rotational speed and offsetting the substrate r esults in negligible differences compared to pure axial rotation. The effec t of rotation on substrate temperature is believed to be more significant t han the effect of substrate rotation on plasma fluid dynamics. (C) 2001 Els evier Science B.V. All rights reserved.