Positive dc bias-enhanced diamond nucleation with high CH 4 concentration

Abstract

A two-step process, positive dc biasing during the substrate nucleation stage but no biasing during growth stage, was used in this study. The diamond nucleation by positive dc bias enhancement on (100) silicon substrate in horizontal microwave plasma chemical vapor deposition from a CH 4+H 2 gas mixture was investigated by scanning electron microscopy, Raman spectroscopy, atomic force microscopy and transmission electron microscopy. It was found that high methane concentration is needed during positive bias step for high nucleation density (>10 10/cm 2). Diamond phase was formed during the biasing step. High quality and polycrystalline diamond was achieved by controlling biasing and deposition conditions. Dense plasma was formed at high methane content in positive BEN step. The changes of various species such as atomic hydrogen and carbonaceous radicals in the CH 4-H 2 plasma during positive dc bias have been identified using optical emission spectroscopy (OES).