PLASMA EFFECTS ON FILM PROPERTIES OF MAGNETRON SPUTTERED CARBON FILMS.

Abstract

Thin, amorphous films of carbon have been deposited by conventional and hollow cathode enhanced magnetron sputtering of a pyrolytic graphite target. Films with thicknesses in the range of 15 to 200 nm were deposited over a pressure range of 50 to 0. 1 mT on variety of substrates. Langmuir probe measurements of the local electron temperature, density and plasma potential were made at several locations in the plasma as well as at the substrate location as a function of pressure in both the conventional mode (50 to 1 mT) and the hollow cathode enhanced magnetron mode (1 to 0. 1 mT). Several film properties were found to vary markedly over the pressure range investigated. For example, electrical resistivity was reduced from about 1 multiplied by 10**6 ohm-cm at 50 mT sputtering pressure to a value of 0. 01 ohm-cm at 0. 1 mT pressure. The optical bandgap was reduced over the same pressure range from 2. 1 to 0. 4 eV. The index of refraction increased from n equals 2 at 50 mT to n equals 2. 7 at 0. 1 mT.