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Proceedings Paper

Vertical integration of array-type miniature interferometers at wafer level by using multistack anodic bonding
Author(s): Wei-Shan Wang; Maik Wiemer; Joerg Froemel; Tom Enderlein; Thomas Gessner; Justine Lullin; Sylwester Bargiel; Nicolas Passilly; Jorge Albero; Christophe Gorecki
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Paper Abstract

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.

Paper Details

Date Published: 26 April 2016
PDF: 7 pages
Proc. SPIE 9890, Optical Micro- and Nanometrology VI, 989011 (26 April 2016); doi: 10.1117/12.2229884
Show Author Affiliations
Wei-Shan Wang, Fraunhofer Institute for Electronic Nanosystems (Germany)
Maik Wiemer, Fraunhofer Institute for Electronic Nanosystems (Germany)
Joerg Froemel, Fraunhofer Institute for Electronic Nanosystems (Germany)
Tom Enderlein, Fraunhofer Institute for Electronic Nanosystems (Germany)
Thomas Gessner, Fraunhofer Institute for Electronic Nanosystems (Germany)
Technische Univ. Chemnitz (Germany)
Justine Lullin, FEMTO-ST (France)
Sylwester Bargiel, FEMTO-ST (France)
Nicolas Passilly, FEMTO-ST (France)
Jorge Albero, FEMTO-ST (France)
Christophe Gorecki, FEMTO-ST (France)

Published in SPIE Proceedings Vol. 9890:
Optical Micro- and Nanometrology VI
Christophe Gorecki; Anand Krishna Asundi; Wolfgang Osten, Editor(s)

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