In this paper, we present a novel MEMS Pirani sensor with triple heat sinks which was designed to measure the pressure inside thin film, wafer level packages. The sensors are made in SOI (silicon on insulator) wafers leading to a very simple fabrication process. The use of relatively thick single crystal silicon for the in plane bridges result in structures with good mechanical properties as compared to alternative surface micromachining processes and reduces problems with buckling and sticking. Since, the proposed Pirani has three heat sinks, the area of heat loss through the ambient gas is greatly enlarged as compared to Pirani sensors with one or two heat sinks, without increasing the size of the sensor. Consequently, a Priani sensor of 336 µm in length has a pressure measurement range of 0.08-200 Torr. Alternative designs have shown measurement ranges varying between 0.02 and 500 Torr. This new type of Pirani sensor is small enough to be easily integrated in small volume wafer level packages.@en

In the growing MEMS market Wafer Level Thin Film Packages can be applied to an increasing numer of MEMS devices. This paper discusses the effects of common assembly processes on wafer level thin film packages. All assembly processes are discussed and the effects of the process on the structures is presented. From the assembly tests the grinding process poses the largest hazards followed by dicing, moulding, wire bonding and finally die attachment. A number of improvements related to etch holes and sealing structures are proposed to enhance the crack resistance and robustness.@en

In this paper, the gas dependence of the Q factor in MEMS resonators is investigated and verified by the measurements in different ambient gases, with pressures changing from vacuum to atmosphere. The experimental results agree favorably with the existing theoretical models. The findings in the work suggest that low molecular weight gasses can be used to enhance the Q factor without the need for external low pressure.@en

In this paper, outgassing of the thin film vacuum package is analyzed by integrated MEMS (Microelectromechanical system) resonator and RBS (Rutherford backscattering spectroscopy). Outgassing behavior of different thin film packaging materials is studied by exodiffusion experiments. It is demonstrated that a high temperature pre anneal will greatly reduce the outgassing but can not eliminate it.@en