Control of Hydrogenation Patterning for CVD Diamond Substrates by AFM Local Anodic Oxidation

Abstract

Local anodic oxidation (LAO) of hydrogenated CVD diamond surfaces was carefully investigated as a function of the scanning speed, relative humidity and bias voltage. As examples, perfect control of the width of the oxidised lines between 80 and 110 nm was demonstrated for scanning speeds between 20 and 110 nm s^-1, at 60% relative humidity, and between 45 and 90 nm by switching the humidity from 40% to 60%. The oxidation process is indicated by the decay of the current during the LAO process, which is concluded in about 10 s. The interpretation of the results, which in the literature oscillates between digging grooves and the creation of oxidised bumps, is still quite difficult, since it depends on the AFM mode ('contact' or 'non-contact') which was used for LAO. A true oxidation process is more likely to occur, as indicated by the present results, and this is in agreement with the presence of oxygen in surface analysis data.