High hermetic performance of glass frit for MEMS package

Low-temperature co-fired ceramics (LTCC) enable the fabrication of microfluidic elements such as channels and embedded cavities in electrical devices. Hence, LTCC facilitate the realization of complex and integrated microfluidic devices. Examples can be applied in many areas like reaction chambers for synthesis of chemical compounds. However, for many applications it is necessary to have an optically transparent interface to the surroundings. The integration of optical windows in LTCC opens up a wide field of new and innovative applications such as the observation of chemiluminescent reactions. These chemical reactions emit electromagnetic radiation and thus offer a method for noninvasive detection. Thin glasses ( 500 lm) were bonded by thermocompression onto a LTCC substrate. As the bonding agent, a glass frit paste was used. Borosilicate glasses, fused silica as well as silicon were successfully bonded onto LTCC. To join materials with a large coefficient of thermal expansion mismatch (i.e., fused silica and LTCC), it is necessary to limit the heat input to the bond interface. Therefore, a heating structure was integrated into the LTCC substrate beneath the bond interface. This bonding process provides a gas-tight optical port with a high bond strength. † Present address:

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“…All fabricated bond interfaces show excellent leak rates below 5 × 10 −10 mbar·l/s, what is comparable to other hermetic packages …”

Section: Testing For Leaks and Evaluating Bond Strengthsupporting

confidence: 58%

Design and Fabrication of Transparent and Gas‐Tight Optical Windows in Low‐Temperature Co‐Fired Ceramics

Welker

Geiling

Bartsch

et al. 2013

Int J Applied Ceramic Tech

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“…Packaging is an essential technological step for encapsulating and protecting sensitive MEMS structures such as accelerometers, resonators, micromirrors and gyroscopes against atmospheric influences, especially moisture. In other words, most MEMS devices must operate in a hermetic package for achieving better performance and reliability [5][6][7][8]. In the past decades, glass frit bonding has been one of the most widely used bonding materials for wafer level vacuum packaging.…”

Section: Introductionmentioning

confidence: 99%

Study of glass frit induced stiction using a micromirror array

Ling

Coster

Witvrouw

et al. 2012

Microelectronics Reliability

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“…Glass frits are of particular interest due to the leak proof and robust sealing mechanism, the required low bonding temperature(<450℃), varied thermal expansion coefficient to choose , and conforming to the surfaces being bonded even to the extent of allowing metallic feed-through to be included in the joining layer . [1,2] Glass frit bonding between double wafers has been extensively researched. [3] The packaging structure between two wafers has high bonding strength and low leakage rate.In MEMS packaging area, multilayer wafer bonding layer by layer is requisite such as devices with cantilever beam or tuning fork resonator inside.…”

mentioning

confidence: 99%

Glass Frit as a Hermetic Joining Material for Bonding among Three Wafers with Metallic Film Feed-Through

Zhao

Wang

Zhang

et al. 2014

KEM

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This paper reports a sealing process for reliable hermetic wafer-scale packaging among three wafers forming sandwich structure by glass frit. The process could be applied to Si, quartz crystal, SiC wafers and so on. The device wafer is bonded to the capping wafer in the first step and to another capping wafer forming vacuum-cavities in the second step. Experimental results indicate that the average bonding strength of packaging structure reached as high as 0.85kg/mm2 fulfilling MIL-STD-833E standard. The average leakage rate fits the standard of GJB-548A.This paper also realizes glass frit hermetic bonding in the case of Au/Cr and Pt/Ti film feed-through deposited on the device wafer.Experimental results indicate that Pt/Ti film feed-through hold up to bonding temperature cycling and avoid dissolution and adherence reduction compared with Au/Cr film feed-through

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High hermetic performance of glass frit for MEMS package

Cited by 7 publications

References 12 publications

Design and Fabrication of Transparent and Gas‐Tight Optical Windows in Low‐Temperature Co‐Fired Ceramics

Design and Fabrication of Transparent and Gas‐Tight Optical Windows in Low‐Temperature Co‐Fired Ceramics

Study of glass frit induced stiction using a micromirror array

Glass Frit as a Hermetic Joining Material for Bonding among Three Wafers with Metallic Film Feed-Through

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