Diamond synthesis on Si by plasma chemical vapor deposition using microwave sheath-voltage combination plasma

Abstract

Microwave sheath-voltage combination plasma (MVP) represents a new method to generate plasma and coat diamond-like carbon films onto the three-dimensional metal surfaces . The present work investigates the synthesis of diamonds using MVP deposition, focusing in particular on how pressure and bias voltage affect the diamond structure. Using MVP, silicon wafers were coated with diamond in gas mixtures of methane and hydrogen with the substrate bias ranging from 0 to −200 V and pressure ranging from 800 to 1000 Pa. Although diamond particles are created with the substrate biased between 0 and −200 V at 1% methane concentration, at −200 V the particles are affixed atop Si or SiC cones that form on the Si substrate due to plasma etching . X-ray diffraction analysis reveals that the diamond structure is created up to a bias voltage of −100 V at 3% methane concentration. Nanodiamond is produced at methane concentration of 3%. These experiments suggest that MVP, a new diamond coating method, makes depositing the diamond on 3D shape substrates possible. • Diamond coatings are deposited by microwave sheath-voltage combination plasma. • Higher substrate temperature with nonzero bias voltage than with zero bias voltage • Higher negative bias produces cone-like structures on the substrate.