The need to reach high and stable values of the Q-factor is one of the most important issues of resonant MEMS in order to make high-performance sensors. The Q-factor is strongly influenced by the internal environment of the MEMS packaging, by total pressure and by gas composition. The most experienced and technically accepted way to keep the atmosphere stable in a hermetically sealed device is to use a getter material that is able to chemically absorb active gases under vacuum or in inert gas atmosphere for the lifetime of the devices. MEMS hermetically bonded devices such as gyroscopes, accelerometers, pressure and flow sensors, IR sensors, RF-MEMS and optical mirrors requires getter thin film solutions to work properly. Getter technical solution for wafer to wafer hermetically bonded MEMS systems is PaGeWafer, a silicon, glass or ceramic wafer ("cap wafer") with patterned getter film, few microns thick. In this paper, first the theoretical evaluation of Q-factor of a MEMS resonant structure in presence of a getter film is investigated and compared to the results of a Residual Gas Analysis of the same MEMS resonant structure and with the conventional measurement of Q-factor. Using getter thin film technology, total pressures down to 10-4 mbar with corresponding high and stable Q-factors have been achieved in MEMS resonant structures. We were therefore able to confirm that getter films can provide high Q-values, stability of sensor signal, performances stability during the lifetime, removal of dangerous gases like H2 and H2O in hermetically sealed MEMS resonant structures.
In OLED organic layers electron injection is improved by using alkali metals as cathodes, to lower work function or, as dopants of organic layer at cathode interface.
The creation of an alkali metal layer can be accomplished through conventional physical vapor deposition from a heated dispenser. However alkali metals are very reactive and must be handled in inert atmosphere all through the entire process. If a contamination takes place, it reduces the lithium deposition rate and also the lithium total yield in a not controlled way.
An innovative alkali metal dispensing technology has been developed to overcome these problems and ensure OLED alkali metal cathode reliability.
The alkali Metal dispenser, called Alkamax, will be able to release up to a few grams of alkali metals (in particular Li and Cs) throughout the adoption of a very stable form of the alkali metal.
Lithium, for example, can be evaporated “on demand”: the evaporation could be stopped and re-activated without losing alkali metal yield because the metal not yet consumed remains in its stable form.
A full characterization of dispensing material, dispenser configuration and dispensing process has been carried out in order to optimize the evaporation and deposition dynamics of alkali metals layers.
The study has been performed applying also inside developed simulations tools.