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Sensors 2008, 8(11), 7438-7452; doi:10.3390/s8117438
Article

Sputtered Encapsulation as Wafer Level Packaging for Isolatable MEMS Devices: A Technique Demonstrated on a Capacitive Accelerometer

1,* , 1, 1
 and 2
Received: 11 October 2008; in revised form: 11 November 2008 / Accepted: 14 November 2008 / Published: 19 November 2008
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)
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Abstract: This paper discusses sputtered silicon encapsulation as a wafer level packaging approach for isolatable MEMS devices. Devices such as accelerometers, RF switches, inductors, and filters that do not require interaction with the surroundings to function, could thus be fully encapsulated at the wafer level after fabrication. A MEMSTech 50g capacitive accelerometer was used to demonstrate a sputtered encapsulation technique. Encapsulation with a very uniform surface profile was achieved using spin-on glass (SOG) as a sacrificial layer, SU-8 as base layer, RF sputtered silicon as main structural layer, eutectic gold-silicon as seal layer, and liquid crystal polymer (LCP) as outer encapsulant layer. SEM inspection and capacitance test indicated that the movable elements were released after encapsulation. Nanoindentation test confirmed that the encapsulated device is sufficiently robust to withstand a transfer molding process. Thus, an encapsulation technique that is robust, CMOS compatible, and economical has been successfully developed for packaging isolatable MEMS devices at the wafer level.
Keywords: Silicon encapsulation; sputtering; wafer level packaging; capacitive accelerometer; liquid crystal polymer Silicon encapsulation; sputtering; wafer level packaging; capacitive accelerometer; liquid crystal polymer
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Hamzah, A.A.; Yunas, J.; Majlis, B.Y.; Ahmad, I. Sputtered Encapsulation as Wafer Level Packaging for Isolatable MEMS Devices: A Technique Demonstrated on a Capacitive Accelerometer. Sensors 2008, 8, 7438-7452.

AMA Style

Hamzah AA, Yunas J, Majlis BY, Ahmad I. Sputtered Encapsulation as Wafer Level Packaging for Isolatable MEMS Devices: A Technique Demonstrated on a Capacitive Accelerometer. Sensors. 2008; 8(11):7438-7452.

Chicago/Turabian Style

Hamzah, Azrul A.; Yunas, Jumril; Majlis, Burhanuddin Y.; Ahmad, Ibrahim. 2008. "Sputtered Encapsulation as Wafer Level Packaging for Isolatable MEMS Devices: A Technique Demonstrated on a Capacitive Accelerometer." Sensors 8, no. 11: 7438-7452.



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