Fabrication of large-scale monocrystalline silicon micro-mirror arrays using adhesive wafer transfer bonding

Fabian Zimmer; Frank Niklaus; Martin Lapisa; Thomas Ludewig; Martin Bring; Martin Friedrichs; Thor Bakke; Harald Schenk; Wouter van der Wijngaart

doi:10.1117/12.808694

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18 February 2009 Fabrication of large-scale monocrystalline silicon micro-mirror arrays using adhesive wafer transfer bonding

Fabian Zimmer, Frank Niklaus, Martin Lapisa, Thomas Ludewig, Martin Bring, Martin Friedrichs, Thor Bakke, Harald Schenk, Wouter van der Wijngaart

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Proceedings Volume 7208, MOEMS and Miniaturized Systems VIII; 720807 (2009) https://doi.org/10.1117/12.808694
Event: SPIE MOEMS-MEMS: Micro- and Nanofabrication, 2009, San Jose, California, United States

Abstract

Today, spatial light modulators (SLMs) based on individually addressable micro-mirrors play an important role for use in DUV lithography and adaptive optics. Especially the mirror planarity and stability are important issues for these applications. Mono-crystalline silicon as mirror material offers a great possibility to combine the perfect surface with the good mechanical properties of the crystalline material. Nevertheless, the challenge is the integration of mono-crystalline silicon in a CMOS process with low temperature budget (below 450°C) and restricted material options. Thus, standard processes like epitaxial growth or re-crystallization of poly-silicon cannot be used. We will present a CMOS-compatible approach, using adhesive wafer transfer bonding with Benzocyclobutene (BCB) of a 300nm thin silicon membrane, located on a SOI-donor wafer. After the bond process, the SOI-donor wafer is grinded and spin etched to remove the handle silicon and the buried oxide layer, which results in a transfer of the mono-crystalline silicon membrane to the CMOS wafer. This technology is fully compatible for integration in a CMOS process, in order to fabricate SLMs, consisting of one million individually addressable mono-crystalline silicon micro-mirrors. The mirrors, presented here, have a size of 16×16 μm². Deflection is achieved by applying a voltage between the mirrors and the underlying electrodes of the CMOS electronics. In this paper, we will present the fabrication process as well as first investigations of the mirror properties.

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Fabian Zimmer, Frank Niklaus, Martin Lapisa, Thomas Ludewig, Martin Bring, Martin Friedrichs, Thor Bakke, Harald Schenk, and Wouter van der Wijngaart "Fabrication of large-scale monocrystalline silicon micro-mirror arrays using adhesive wafer transfer bonding", Proc. SPIE 7208, MOEMS and Miniaturized Systems VIII, 720807 (18 February 2009); https://doi.org/10.1117/12.808694

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