MEMS devices are built with semiconductor equipment. But their failure mechanisms and reliability concerns are completely different from those of ICs. One major concern with MEMs is stiction, or the propensity of two silicon surfaces to stick to each other if they touch. Another is packaging, one of the most difficult and expensive matters to address. Because optical MEMS devices contain exposed moving parts contaminants can make them stop functioning. For this reason, MEMS wafers must be singulated using specialized techniques. There are only a handful of companies that have successfully dealt with these concerns and are supplying reliable commercial MEMS devices.
With optical MEMS, the high-volume manufacturing needed to detect PPM-level defects and problems in a new manufacturing process does not exist today. Since quality and reliability of optical components are important to the telecom industry, selecting an experienced MEMS supplier is mission critical and great care should be taken to check on suppliers' manufacturing track records.
-Scott Blackstone, optical MEMS product line director at Micromachined Products Division for Analog Devices Inc. (Wilmington, Mass.)