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Arrays of monocrystalline silicon micromirrors fabricated using CMOS compatible transfer bonding
KTH, Superseded Departments, Signals, Sensors and Systems.ORCID iD: 0000-0002-0525-8647
KTH, Superseded Departments, Signals, Sensors and Systems.ORCID iD: 0000-0002-9327-2544
KTH, Superseded Departments, Signals, Sensors and Systems.ORCID iD: 0000-0001-9552-4234
2003 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 12, no 4, 465-469 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, we present CMOS compatible fabrication of monocrystalline silicon micromirror arrays using membrane transfer bonding. To fabricate the micromirrors, a thin monocrystalline silicon device layer is transferred from a standard silicon-on-insulator (SOI) wafer to a target wafer (e.g., a CMOS wafer) using low-temperature adhesive wafer bonding. In this way, very flat, uniform and low-stress micromirror membranes made of monocrystalline silicon can be directly fabricated on top of CMOS circuits. The mirror fabrication does not contain any bond alignment between the wafers, thus, the mirror dimensions and alignment accuracies are only limited by the photolithographic steps. Micromirror arrays with 4 x 4 pixels and a pitch size of 16 mum x 16 mum have been fabricated. The monocrystalline silicon micromirrors are 0.34 mum thick and have feature sizes as small as 0.6 mum. The distance between the addressing electrodes and the mirror membranes is 0.8 mum. Torsional micromirror arrays are used as spatial light modulators, and have potential applications in projection display systems, pattern generators for maskless lithography systems, optical spectroscopy, and optical communication systems. In principle, the membrane transfer bonding technique can be applied for integration of CMOS circuits with any type of transducer that consists of membranes and that benefits from the use of high temperature annealed or monocrystalline materials. These types of devices include thermal infrared detectors, RF-MEMS,IS devices, tuneable vertical cavity surface emitting lasers (VCSEL) and other optical transducers.

Place, publisher, year, edition, pages
2003. Vol. 12, no 4, 465-469 p.
Keyword [en]
adhesive bonding, CMOS compatible, membrane transfer bonding, micromirror, monocrystalline silicon, SLM, spatial light modulator, design
National Category
Mechanical Engineering
URN: urn:nbn:se:kth:diva-22732DOI: 10.1109/jmems.2003.815833ISI: 000184649700008OAI: diva2:341430
QC 20100525Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2010-10-19Bibliographically approved
In thesis
1. Assembly of microsystems for optical and fluidic applications
Open this publication in new window or tab >>Assembly of microsystems for optical and fluidic applications
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis addresses assembly issues encountered in optical and fluidic microsystem applications.

In optics, the first subject concerns the active alignment of components in optical fibersystems. A solution for reducing the cost of optical component assembly while retaining submicron accuracy is to integrate the alignment mechanism onto the optical substrate. A polymer V-shaped actuator is presented that can carry the weight of the large components - on a micromechanical scale - and that can generate movement with six degrees of freedom.

The second subject in optics is the CMOS-compatible fabrication of monocrystalline silicon micromirror arrays that are intended to serve as CMOS-controlled high-quality spatial light modulators in maskless microlithography systems. A wafer-level assembly method is presented that is based on adhesive wafer bonding whereby a monocrystalline layer is transferred onto a substrate wafer in a CMOS-compatible process without needing bond alignment.

In fluidics, a hybrid assembly method is introduced that combines two separately micromachined structures to create hotwire anemometers that protrude from a surface with minimum interference with the air flow. The assembled sensor enables one to make accurate time-resolved measurements of the wall shear stress, a quantity that has previously been hard to measure with high time resolution. Also in the field of hotwire anemometers, a method using a hotwire anemometer array is presented for measuring the mass flow, temperature and composition of a gas in a duct.

In biochemistry, a bio-analysis chip is presented. Single nucleotide polymorphism scoring is performed using dynamic allele-specific hybridization (DASH). Using monolayers of beads, multiplexing based on single-bead analysis is achieved at heating rates more than 20 times faster than conventional DASH provides.

Space and material e±ciency in packaging are the focus of the other two projects in fluidics. The first introduces an assembly based on layering conductive adhesives for the fabrication of miniature polymer electrolyte membrane fuel cells. The fuel cells made with this low-cost approach perform among the best of their type to date. The second project concerns a new cross-flow microvalve concept. Intended as a step towards the mass production of large-flow I/P converters, the silicon footprint area is minimized by an out-of-plane moving gate and in-plane, half-open pneumatic channels.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. xiv, 70 p.
Trita-ILA, ISSN 0281-2878 ; 0501
Applied mechanics, microsystem technology, micromachining, assembly, active alignment, BCB, Teknisk mekanik
National Category
Mechanical Engineering
urn:nbn:se:kth:diva-120 (URN)91-7283-958-9 (ISBN)
Public defence
2005-02-11, Kollegiesalen, Valhallavägen 79, Stockholm, 14:00
QC 20101019Available from: 2005-02-09 Created: 2005-02-09 Last updated: 2010-10-19Bibliographically approved

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