A Study of Hot Filament Chemical Vapor Deposition of Diamond Thin Films as a Function of Reaction Chamber Variables

摘要

A major obstacle to a more widespread use of diamond thin films is their surface roughness and nonuniformity. It is therefore desirable to minimize the diamond crystal size in these films to make the films smoother and more useful. We report on a number of approaches attempted in a hot filament chemical vapor deposition (HFCVD) system to minimize the crystal size in diamond thin films. The film morphology was studied as function of the following reaction chamber variables: gas composition (Ar:CH_4:H_2 and CH_4:H_2 mixtures), the substrate-filament distance, temperatures of the substrate and filament, chamber pressure, and distance on the substrate from the filament position. Some of the approaches used were more successful than others in minimizing the diamond crystal size and useful insights were gained about diamond crystal growth behaviors under different conditions. Scanning electron microscopy (SEM) was used to characterize the morphology in all the cases and Raman spectroscopy was used for some of the specimens.