Effect of CH4 concentration on the early growth stage of patterned diamond using high seeding density and hot filament chemical vapor deposition.

A bottom-up method is described to grow patterned polycrystalline diamond on silicon substrates using polymer assisted seeding and photolithography. Diamond seeding densities were > 1011 cm−2. The pattern consists of well-defined features ranging from microns to millimeters in size. A systematic study was carried out to investigate the effects of CH4 concentration (1.5, 2.0, 2.5, and 3.0% in H2) on diamond grown using hot-filament chemical vapor deposition. The study is focused on the early growth regime following 30 min, 45 min, and 2 h process times. Scanning electron microscopy and atomic force microscopy measurements are used to study thickness, growth rate, grain size, grain morphology, and surface roughness of the polycrystalline diamond. SEM cross section images confirm the growth of high seeding diamond films without voids at the substrate interface. An increasing trend of lateral particles sizes, with increasing CH4, is observed reaching ~ 365 nm at the highest CH4 concentration. Material quality is checked using UV micro-Raman spectroscopy including line scans to investigate uniformity of patterned features. The results show that higher CH4 concentration leads to narrow linewidths and higher relative integrated intensities of diamond. These characteristics are consistent with improvements in the diamond quality in the early growth stages. [ABSTRACT FROM AUTHOR]