The term “CMOS MEMS” most often describes pro- cesses that create microstructures directly out of the metal/ dielectric interconnect stack in foundry CMOS. The metal- lization and dielectric layers, normally used for electrical interconnect, now serve a dual function as structural layers. For example, the suspended n-well of Figure 3(d) is consid- ered CMOS MEMS, since its beam suspension is made from the CMOS interconnect stack. There is significant motivation for making MEMS out of CMOS. Leveraging foundry CMOS for MEMS is fast, reliable, repeatable, and economical. Electronics can be placed directly next to microstructures, enabling arrayed systems on chip. In CMOS MEMS, multiple conductors can be placed inside of the microstructures,.
