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The development of sensitive MEMS now requires either high purity inert atmosphere or a vacuum environment. Therefore, encapsulation is mandatory to ensure performances over the projected lifetime of the devices. The knowledge of the behavior of the MEMS components and assembly with respect to vacuum compatibility is therefore of outmost importance, both to understand and reduce the impurities' release mechanisms and to design a suitable solution to the lifetime issue. This solution is based on the use of specific getter materials and configurations to be incorporated into the MEMS cavity. Outgassing and residual gas composition data are necessary to address the choice of the proper getter material and provide information on the design of the getter. Different solutions can be envisaged depending on the type of gas to be sorbed, the process constraints and the operating conditions of each specific device. If moisture is the main gas to be removed from the cavity, the choice is between physical and chemical dryers. In case other species have also to be sorbed, then the choice of a non-evaporable getter (NEG) has to be preferred. The various getter materials and solutions to the vacuum problems in MEMS will be discussed in detail.

The exploitation of OLED displays is strongly dependent on an efficient system of encapsulation and moisture removal from the device. The effectiveness of the device design and materials selection can be properly addressed by the quantitative analysis of moisture and impurities levels by means of a dedicated mass spectrometric technique.

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