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

Abstract

The effects of substrate rotation on the chemical vapor deposition (CVD) of diamond is investigated utilizing a Triple Torch Plasma Reactor (TTPR) activation source. Diamond deposition experiments are conducted with an Ar–H 2–CH 4 plasma gas mixture at reduced pressures. Substrate rotation is achieved by means of a variable speed DC gear motor used to rotate the substrate shaft. 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 uniformity of the deposit are found to be enhanced, and deposit roughness decreased by rotating, and rotating plus offsetting the substrate when compared to a stationary substrate. Rotational speed and offsetting the substrate results in negligible differences compared to pure axial rotation. The effect of rotation on substrate temperature is believed to be more significant than the effect of substrate rotation on plasma fluid dynamics.