Low-temperature vacuum hermetic wafer-level package for uncooled microbolometer FPAs

S. Garcia-Blanco; P. Topart; Y. Desroches; J.S. Caron; F. Williamson; C. Alain; H. Jerominek

doi:10.1117/12.761324

18 February 2008 Low-temperature vacuum hermetic wafer-level package for uncooled microbolometer FPAs

S. Garcia-Blanco, P. Topart, Y. Desroches, J.S. Caron, F. Williamson, C. Alain, H. Jerominek

Proceedings Volume 6884, Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS VII; 68840P (2008) https://doi.org/10.1117/12.761324
Event: MOEMS-MEMS 2008 Micro and Nanofabrication, 2008, San Jose, California, United States

Abstract

Micro-Electro-Mechanical Systems (MEMS) packaging constitutes most of the cost of such devices. For the integration of MEMS with microelectronics systems to be widespread, a drastic reduction of the overall price is required. Wafer-level-packaging allows a fundamental reduction of the packaging cost by combining wafer-level microfabrication techniques with wafer-to-wafer bonding. To achieve the vacuum atmosphere required for the operation of many MEMS devices, bonding techniques such as anodic bonding, eutectic bonding, fusion bonding and gold to gold thermocompression bonding have been utilized, which require relatively high temperatures (>300°C) being in some cases incompatible with MEMS and microelectronics devices. Furthermore, to maintain vacuum integrity over long periods of time, getters requiring high activation temperatures are usually employed. INO has developed a hybrid wafer-level micropackaging technology based on low temperature fluxless solder joints in which the micropackaged MEMS device is not exposed to a temperature over 150°C. The micropackages have been designed for 160×120 microbolometer FPAs. Ceramic spacers are patterned by standard microfabrication techniques followed by laser micromachining. AR-coated floatzone silicon IR windows are patterned with a solderable layer. Both, microbolometer dies and windows are soldered to the ceramic tray by a combination of solder paste stencil printing, reflow and fluxless flip-chip bonding. A low temperature getter is also introduced to control outgassing of moisture and CO₂ during the lifetime of the package. Vacuum sealing is carried out by locally heating the vacuum port after bake out of the micropackages. In this paper, the vacuum integrity of micropackaged FPA dies will be reported. Base pressures as low as 5 mTorr and equivalent flow rates at room temperature of 4×10^-14 Torr.l/s without getter incorporation have been demonstrated using integrated micro-pressure gauges. A study of the influence of different packaging parameters on the lifetime of micropackages will be presented.

Citation Download Citation

S. Garcia-Blanco, P. Topart, Y. Desroches, J.S. Caron, F. Williamson, C. Alain, and H. Jerominek "Low-temperature vacuum hermetic wafer-level package for uncooled microbolometer FPAs", Proc. SPIE 6884, Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS VII, 68840P (18 February 2008); https://doi.org/10.1117/12.761324

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