Until now, the determination of microelectronic packages hermeticity has been related to the MIL-STD-883 method 1014 which is based on the helium leak detection method. But this method is no longer suited for small packages due to the resolution limit of the apparatus. Indeed, leaks induced by nonhermetic MEMS packages are often one order of magnitude smaller than the resolution of the helium leak tester. Consequently, characterization of MEMS packages requires new methodologies to measure hermeticity accurately. Two methods will be investigated in the context of this study: the membrane deflection measurement, when exposed to different pressures, using optical profilometry, and the measurement of the variation of gas concentration in a sealed silicon cavity by Fourier transform infrared spectroscopy (FTIR). The calculated leak rates are compared for samples where the standard fine leak test gave no results. The values obtained for the leak rates with the optical test and FTIR test for the same sample are identical, showing the relevance of these two methods. FTIR spectroscopy is a promising method which enhances standard detection limits. It can be used as a reliable process quality control tool.
-RF MEMS have been pursued for more than a decade as a solution to high-performance on-chip fixed, tunable and switchable passives. However, the implementation of RF-MEMS into products has remained elusive. This is partly due to special-purpose processes that only supported a narrow application field, in many cases optimized for single devices. This prevented aggregation of volumes to justify the manufacturing infrastructure of even a single production foundry. This paper presents a single process that has been implemented in multiple foundries and highlights a wide range of high-performance devices including switches, inductors, varactors, and phase-shifters that have been or are being built using this process. This process thus forms the foundation for a wide range of reconfigurable and tunable RF passive circuits.
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