The bias-enhanced nucleation (BEN) of diamonds on a Si substrate, using a SiO2 mask and microwave plasma-enhanced chemical vapor deposition (MPE-CVD), was examined. Experimental results indicate that the electron-emission-enhanced nucleation mechanism proposed herein governs the nucleation of diamonds on the partially patterned SiO2/Si substrate. The variation of nucleation density on the partially patterned SiO2/Si substrate also reveals that the BEN of diamonds in the MPE-CVD process follows the proposed mechanism.