TY - JOUR
T1 - Silicon full wafer bonding with atomic layer deposited titanium dioxide and aluminum oxide intermediate films
AU - Puurunen, R. L.
AU - Suni, T.
AU - Ylivaara, O. M E
AU - Kondo, H.
AU - Ammar, M.
AU - Ishida, T.
AU - Fujita, H.
AU - Bosseboeuf, A.
AU - Zaima, S.
AU - Kattelus, H.
PY - 2012/12
Y1 - 2012/12
N2 - 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 1600 mJ/m2, enabling the fabrication of SOI wafers with buried TiO2.
AB - 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 1600 mJ/m2, enabling the fabrication of SOI wafers with buried TiO2.
KW - Al O
KW - ALD
KW - Atomic layer deposition
KW - Silicon-on-insulator
KW - SOI
KW - TiO
KW - Wafer bonding
UR - http://www.scopus.com/inward/record.url?scp=84870065121&partnerID=8YFLogxK
U2 - 10.1016/j.sna.2012.05.006
DO - 10.1016/j.sna.2012.05.006
M3 - Article
AN - SCOPUS:84870065121
SN - 0924-4247
VL - 188
SP - 268
EP - 276
JO - Sensors and Actuators A: Physical
JF - Sensors and Actuators A: Physical
ER -