Wafer-level heterointegration process of SAW devices and LSI

Kyeongdong Park, Masayoshi Esashi, Shuji Tanaka

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

5 Citations (Scopus)


The direct integration of surface acoustic wave (SAW) devices on top oflarge-scale integrated circuits (LSI) will enable multiband wireless front-ends,one-chip wireless systems, high-performance one-chip oscillators etc. However,this has been difficult, because SAW devices are often fabricated onpiezoelectric crystals with special cut angle, which have different coefficientsof thermal expansion (CTE) from that of Si. In this paper, wafer-bonding-basedintegration technology for a one-chip SAW oscillator is described. A SAWresonator with a resonant frequency of 420 MHz fabricated on 128 Y cut lithiumniobate (LN) was integrated with a BiCMOS oscillator circuit. The key point ofthe developed process is to avoid thermal expansion mismatch problem between LNand Si. The SAW resonators were supported with a Si wafer in a half-diced form,and then bonded to a LSI wafer by Au-Au bonding. Before the Au-Au bonding,bonding surfaces were activated by Ar plasma to reduce bonding temperature.Finally, the Si support wafer was removed by the sacrificial etching of a Geinterlayer. The developed process can be basically applied to not only SAWdevices but also a variety of non-Si devices.

Original languageEnglish
Title of host publication2010 IEEE International Ultrasonics Symposium, IUS 2010
Number of pages4
Publication statusPublished - 2010
Event2010 IEEE International Ultrasonics Symposium, IUS 2010 - San Diego, CA, United States
Duration: 2010 Oct 112010 Oct 14

Publication series

NameProceedings - IEEE Ultrasonics Symposium
ISSN (Print)1051-0117


Conference2010 IEEE International Ultrasonics Symposium, IUS 2010
Country/TerritoryUnited States
CitySan Diego, CA


  • Lithium niobate
  • Low temperature bonding
  • SAW device
  • Wafer-level integration


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