Sputtered encapsulation as wafer level packaging for isolatable MEMS devices: A technique demonstrated on a capacitive accelerometer

Azrul Azlan Hamzah, Jumril Yunas, Burhanuddin Yeop Majlis, Ibrahim Ahmad

Research output: Contribution to journalArticle

17 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)7438-7452
Number of pages15
JournalSensors
Volume8
Issue number11
DOIs
Publication statusPublished - 01 Nov 2008

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Electrical and Electronic Engineering

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