Silicon full wafer bonding with atomic layer deposited titanium dioxide and aluminum oxide intermediate films

Silicon full wafer bonding with atomic layer deposited titanium dioxide and aluminum oxide intermediate films

Silicon-on-insulator (SOI) wafers made by direct wafer bonding are widely used as starting substrates for microelectromechanical systems (MEMS) fabrication. Adding another layer next to the SiO2 SOI, or replacing it with another material, will be a way to tailor the SOI wafers further. Atomic layer...

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Bibliographic Details
Published in:Sensors and actuators. A. Physical. Vol. 188; pp. 268 - 276
Main Authors: Puurunen, R.L., Suni, T., Ylivaara, O.M.E., Kondo, H., Ammar, M., Ishida, T., Fujita, H., Bosseboeuf, A., Zaima, S., Kattelus, H.
Format: Journal Article
Language:English
Published: Elsevier B.V 01-12-2012
Subjects:
Al2O3
ALD
Aluminum oxide
Annealing
Atomic layer deposition
Bonding
Deposition
Microelectromechanical systems
Silicon
Silicon-on-insulator
SOI
TiO2
Titanium dioxide
Wafer bonding
Wafers
Wafer bonding
Atomic layer deposition
Silicon-on-insulator
ALD
SOI
Al2O3
TiO2
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Summary:Silicon-on-insulator (SOI) wafers made by direct wafer bonding are widely used as starting substrates for microelectromechanical systems (MEMS) fabrication. Adding another layer next to the SiO2 SOI, or replacing it with another material, will be a way to tailor the SOI wafers further. Atomic layer deposition (ALD) can be used to deposit pinhole-free nanometer-thin conformal and smooth inorganic films at low temperatures, making it of interest for many applications in MEMS. In this work, the direct wafer bonding of ALD TiO2, and Al2O3 for reference, is investigated, eventually in order to fabricate SOI wafers with buried ALD oxides. Finding suitable process conditions for TiO2 bonding was challenging: bonding could not be made for TiO2 deposited directly on SiO2 or Si, and annealing at 1100°C gave non-continuous Ti-containing layers. Using a 2-nm Al2O3 under-layer and annealing at 700°C gave void-free bonding with continuous TiO2 and a bond strength of approximately 1600mJ/m2, enabling the fabrication of SOI wafers with buried TiO2.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:0924-4247
1873-3069
DOI:10.1016/j.sna.2012.05.006