Method for nucleation and deposition of diamond using hot-filament DC plasma

摘要

A method and apparatus for nucleation and growth of diamond by hot-filament DC plasma deposition. The apparatus uses a resistively heated filament array for dissociating hydrogen in the reactant gas. For two sided diamond growth, configurations of substrate-hot filament-grid-hot filament-substrate or substrate-hot filament-hot filament-substrate configuration are used. For the latter configuration, two independent arrays of filaments serve as both hot filament and grid, and AC or DC plasma is maintained between the filament arrays. For this and the other electrode configurations, the grid electrode is positively biased with respect to the hot filaments to maintain a plasma. The plasma potential gradient across the grid and the hot-filament draws ions from the plasma towards the filaments. To further increase deposition rates, the filament array is biased negatively with respect to the substrate holder so that a DC plasma is also maintained between the substrate and filament array. During nucleation, the filament adjacent to the substrate holder is biased positively relative to the substrate so that more ions are accelerated towards the substrate, which in turn enhances the flow of growth precursors towards the substrate resulting in a high diamond nucleation density on the substrate without the need for scratching or diamond-seeding pretreatment. This nucleation method simplifies the growth process and provides a convenient and economical means for heteroepitaxial growth of diamond nuclei on single crystal substrates like Si (100).