A Parylene temporary packaging technique for MEMS wafer handling

This paper presents a wafer-level temporary packaging technique utilizing a chemical vapor deposited (CVD) poly-(p-xylylene) polymer Parylene film, and oxygen plasma etching. As a test case, released, unpackaged accelerometers fabricated in a SiGe MEMS above IC technology were coated with two different types of Parylene, Parylene N and Parylene C respectively, as dicing protection. Oxygen plasma is used to etch the Parylene and to release the freestanding structures after dicing. The final releasing results are compared, and Parylene N turns out to be the best material for temporary packaging. The devices are electrostatically characterized after the Parylene coating. The results demonstrate the feasibility of using Parylene as a temporary protective material for both metal and semiconductor MEMS devices, to prevent any damage during subsequent wafer handling and dicing.