The application of adaptive optics in astronomy requires increasingly compact deformable optical components with a high density of actuators, able to provide strokes of several micrometers. The main problem of the use of adaptive optics in more mainstream areas is the cost, the size and consequently the weight of the system. This paper presents the design and the results obtained with the deformable mirror under development. The system will have a continuous reflective membrane of 1 cm2 driven by 64 closing gap actuators operating in contact. In the following this type of actuators is called “zipping actuators”. Applying 100 V to some 800 μm wide zipping actuators results in an electrostatic force of 100 μN and a mirror displacement of 6 μm. Recent tests of the electric behaviour show linearity between applied tension and resulting displacement as well as a good reproducibility. We also present analysis and results obtained on silicon or polymer (BCB) membranes which have to be attached on the actuator array. A preliminary assembled component made of one actuator sealed to a 5 μm thick polymer 5 × 5 mm2 (BCB) membrane has demonstrated the feasibility of deforming such a small membrane by 3 μm, which is very promising.
For several kinds of MEMS (gyrometers, accelerometers, RF MEMS, bolometers, vacuum allows a significant improvement of performances. Leti has developed a high performance sensor operating at a pressure lower than 10-3 mbar. In a first phase, a ceramic vacuum packaging has been developed: the device is encapsulated in a cavity containing a getter. However, this technique increases considerably the fabrication costs, because it is made at the chip level. For that reason, Leti has also developed wafer-level vacuum packaging process.
The process to manufacture encapsulated devices is presented in this paper. The vacuum function is obtained thanks to an additional wafer (glass or silicon wafer), which supports getters. This wafer is bonded by an hermetic bonding. Characterisation of different kinds of bonding, in term of hermeticity, is presented.
First chips manufactured with this process have been tested. The vacuum level in the cavities has been measured, and was lower than 10-3 mbar. Moreover, vacuum evolution during 6 months does not show pressure increase.
This process can be easily adapted to several MEMS applications. With these experiments, Leti has so proved the possibility of manufacturing low cost vacuum packaged MEMS.