Enea Rizzi

Outgassing and Gettering

Outgassing is an unavoidable issue and although the cleaning process and long baking are carried out, the effect can be limited only by using the getter technology. This technology absorbs the residual gases trapped in the device during the process and maintains the pressure at a very low level for the required lifetime, limiting the gas flux. It has been described that there are gases remaining inside MEMS devices that need a vacuum or other stable pressure to operate properly. The MEMS packaging technology moved from hermetic vacuum discrete packages to vacuum wafer-level packages. Conventional packaging of microelectronic and optoelectronic devices is usually stable and not affected by the external environment except for a few specific cases. Vacuum wafer-level packaging is a very effective technique to produce low-cost, hermetically sealed packages for micromachined sensors and actuators. The main contamination source is the leakage and outgassing phenomena. The leakage is mainly caused by defects in the bonding frame and can be solved by a suitable improvement of the technology or accepting a limited yield in the MEMS production. In the case of outgassing a technically viable solution to assure a long lifetime and high reliability to MEMS device is the integration of a getter film. This has also been explained in detail.