Vertical integration of array-type miniature interferometers at wafer level by using multistack anodic bonding

Wei Shan Wang, Maik Wiemer, Joerg Froemel, Tom Enderlein, Thomas Gessner, Justine Lullin, Sylwester Bargiel, Nicolas Passilly, Jorge Albero, Christophe Gorecki

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

2 Citations (Scopus)


In this work, vertical integration of miniaturized array-type Mirau interferometers at wafer level by using multi-stack anodic bonding is presented. Mirau interferometer is suitable for MEMS metrology and for medical imaging according to its vertical-, lateral- resolutions and working distances. Miniaturized Mirau interferometer can be a promising candidate as a key component of an optical coherence tomography (OCT) system. The miniaturized array-type interferometer consists of a microlens doublet, a Si-based MEMS Z scanner, a spacer for focus-adjustment and a beam splitter. Therefore, bonding technologies which are suitable for heterogeneous substrates are of high interest and necessary for the integration of MEMS/MOEMS devices. Multi-stack anodic bonding, which meets the optical and mechanical requirements of the MOEMS device, is adopted to integrate the array-type interferometers. First, the spacer and the beam splitter are bonded, followed by bonding of the MEMS Z scanner. In the meanwhile, two microlenses, which are composed of Si and glass wafers, are anodically bonded to form a microlens doublet. Then, the microlens doublet is aligned and bonded with the scanner/spacer/beam splitter stack. The bonded array-type interferometer is a 7- wafer stack and the thickness is approximately 5mm. To separate such a thick wafer stack with various substrates, 2-step laser cutting is used to dice the bonded stack into Mirau chips. To simplify fabrication process of each component, electrical connections are created at the last step by mounting a Mirau chip onto a flip chip PCB instead of through wafer vias. Stability of Au/Ti films on the MEMS Z scanner after anodic bonding, laser cutting and flip chip bonding are discussed as well.

Original languageEnglish
Title of host publicationOptical Micro- and Nanometrology VI
EditorsWolfgang Osten, Christophe Gorecki, Anand Krishna Asundi
ISBN (Electronic)9781510601352
Publication statusPublished - 2016
EventOptical Micro- and Nanometrology VI - Brussels, Belgium
Duration: 2016 Apr 52016 Apr 7

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceOptical Micro- and Nanometrology VI


  • 3-D integration
  • Anodic bonding
  • Mirau micro-interferometer
  • Multi-wafer bonding


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