Multi-layer single chip MEMS WLCSP fabrication

摘要

A method for fabricating a WLCSP device includes receiving a MEMS cap wafer having a first radius, a MEMS device wafer having a second radius, and a CMOS substrate wafer having a third radius, wherein the first radius is smaller than the second radius, and wherein the second radius is smaller than the third radius, disposing the MEMS cap wafer approximately concentrically upon the MEMS device wafer, disposing the MEMS device wafer approximately concentrically upon the CMOS substrate wafer, disposing a spacer structure upon the MEMS device wafer, wherein the spacer structure comprises a plurality of proximity spacers disposed upon a proximity flag, wherein the plurality of proximity spacers are disposed upon the MEMS device wafer, disposing a mask layer in contact to the plurality of proximity spacers, above and substantially parallel to the MEMS cap wafer, and forming a pattern upon the MEMS cap wafer using the mask layer.