Electroless copper plating on silicon surface for MEMS

Some newly developed techniques of electroless copper plating on a silicon surface for MEMS are reported in this paper. In order to make the electrolessly plated copper film adhere to the silicon surface perfectly, oxygen plasma bombardment combined with ion implantation and KOH etching are proposed to do physical treatment on silicon surface. The high-quality thin copper film with thickness 1500 Å and sheet resistance 0.14Ω/□can be realized through the above process methods. So far the average thickness of the electrolessly plated copper film has reached 5 microns since the new techniques, such as oxygen plasma bombardment silicon surface treatment, are applied in the electroless copper plating. Copper can be selectively plated on the silicon surface but not on the glass surface for the selectivity of plating and the silicon structures are encapsulated completely by the copper film for the conformality.