First, Si tips array are formed mainly by RIE.The effect of over-etched on the apex of Si tip is not evident.It has mainly effect on the shape and the uniformity of Si tips.

• 矽针的形成机制主要为反应式离子蚀刻等向性蚀刻矽，过蚀刻大致上仍能维持小的针尖半径，仅对矽针外型与矽针均匀度有较大影响；