Giorgio Longoni

Stable and Reliable Q-Factor in Resonant MEMS with Getter Film

The objective of this work was to show that the Q-factor of MEMS resonators can be increased and stabilized with the use of getters

Patterned gas absorbing films for assuring long-term reliability and improving performances of mems and omems

Microsensor packaging is one of the most important and challenging technology areas. Many microelectro-mechanical systems (MEMS) and optical MEMS (OMEMS) need to be protected from outside environment stresses: therefore the package must provide an interior environment compatible with the device operation, performances, reliability and lifetime. In addition some MEMS need a specific gas or pressure environment within the package to operate as specified: in particular, OMEMS should be protected against moisture related failures

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.

Chapter Forty – Outgassing and Gettering

Publisher Summary 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 into the device during the process and maintains the pressure at very low level for the required lifetime, limiting the gas flux. It has been clearly described that there are gasses 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 pack- ages. Conventional packaging of microelectronic and optoelectronic devices is usually stable and not affected by the external environment except for a few specific cases. Hydrogen Vacuum wafer-level packaging is a very effective technique to produce low-cost, hermetically sealed packages for micromachined sensors and actuators. The MEMS devices requiring a vacuum to operate properly are shown in pressure level is a key parameter for the quality of the MEMS devices. The main contamination source is the leakage in the bonding and outgassing phenomena. The leakage is mainly caused by defects in the bonding and can be solved by a suitable improvement of the technology or accepting a limited yield in the MEMS production. A technically viable solution to assure a long lifetime and high reliability to MEMS device is the possibility to integrate a getter film. This has also been explained in detail.

P-235L: Late-News Poster: Analysis of the Relationship Between OLED Performance and Dryer Characterization

The successful exploitation of OLED/PLED displays is dependent on the control and removal of moisture from the device. Pixel shrinkage and luminosity reduction during the operating conditions are the most relevant issues, related to the moisture concentration into the device. Results show a strong link with dryer absorbing speed more than total capacity, as forecasted by a suitable model.

Alkali metal sources for OLED devices

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.

53.2: Alkali & Alkaline-Earth Metal Sources for OLED Devices

Electron injection in OLED organic layers is improved by using alkaline-earth or alkali metals as cathode layers or as dopants inside organic layers. An innovative metal dispensing technology has been developed to overcome handling problems and to ensure controlled and reliable metal layers deposition for OLEDs.