PROCESS FOR THE SELECTIVE DEPOSITION OF THIN DIAMOND FILM BY CHEMICAL VAPOUR DEPOSITION

摘要

Thin diamond films are selectively deposited imagewise on a substrate by gas phase synthesis. The substrate may be either a silicon substrate or a basal thin diamond film formed beforehand on a substrate by gas phase synthesis. Where a silicon substrate is used, its surface is i) first abraded to give a surfaee roughness suitable for gas phase synthesis of diamond followed by ii) coating a uniform photoresist layer; iii) exposing the photoresist layer imagewise to illumination; iv) developing the thus-exposed photoresist layer, whereby exposed areas and unexposed areas are distinguished from each ether and the photoresist layer is eliminated in the exposed or unexposed areas; v) subjecting the surface of the silicon substrate in the areas, from which the photoresist layer has been eliminated, to reactive ion etching by a gas mixture discharge of CF4, Ar and O2; vi) dissolving any remaining photoresist layers; and vii) carrying out gas phase synthesis of diamond. When a basal thin diamond film is used, a coating material having a withstandable temperature higher than a substrate temperature required for gas phase synthesis of diamond and having a high etching selectivity to diamond eg amorpheus silicon is needed to cover areas other than areas where new thin diamond film is to be formed. In this embodiment the suriace is coated with a photoresist lithography, amorphous silicon is deposited over entire surfaces, the photoresist layer is lifted thereby producing a coating of silicon in those areas ether than where diamond is to be formed, and diamond is thereafter deposited in the gaps and the silicon depositss are removed. In a further embodiment a thin masking film having a melting point higher than a temperature to be employed for gas phase synthesis of diamond, eg amorphous silicon again, can be used to partly mask the surface of a basal diamond film by first applying the silicon over the entire surface, covering this layer with a photoresist layer by lithography in areas corresponding to where diamond is not to be deposited, eliminating the silicon in the areas not covered by the photoresist, producing a patterned silicon layer and depositing diamond in a pattern conforming with the intended surface areas of the basal thin diamond film. The silicon layer may then be removed. The coated products will find use as heat sinks, insulators in integrated circuits, semiconductor devices and optical waveguides.