Angular Dependence of Surface Energy with Crystal Directions of LiNbO<sub>3</sub> (110) for Nano-Bonding<sup>TM</sup> to Si and α-quartz SiO<sub>2</sub>
ORAL
Abstract
LiNbO3 is a piezo-electric that, when mono-lithically integrated to Si-based materials, yields voice activated chips.
Current bonding methods include hetero-epitaxy and Direct Wafer Bonding (DWB). However, hetero-epitaxy causes lattice strain, since the lattice constant of LiNbO3 is heavily mismatched with Si (100) and α-quartz SiO2 (100). Thermal expansion mismatch during DWB causes fractures of LiNbO3. Also, LiNbO3 decomposes into Li2O5 and Li+ at T > 493K. Instead, this work uses Nano-BondingTM, 1 (NB) and Surface Energy Engineering to modify surface energies into ‘far-from-equilibrium’ states so that when nano-contacted, a 2D-precursor phase forms to catalyze bonding.
Three Liquid Contact Angle Analysis (3LCAA) can map different angular directions on 6” LiNbO3 (110), Si (100), and α-quartz SiO2 (100) wafers. Water contact angles are found to vary significantly, by 50%, from 41.8 ± 1.5° to 59.8 ± 1.5°, as a function of crystal direction. Correlation between surface structure and surface energies along different crystal directions will be discussed.
1 Herbots et al. US Pat. 6613677 (2003), 7,851,365 (2010), 9,018,077 (2015), 9,589,801 (2017), pend. (2020)
Current bonding methods include hetero-epitaxy and Direct Wafer Bonding (DWB). However, hetero-epitaxy causes lattice strain, since the lattice constant of LiNbO3 is heavily mismatched with Si (100) and α-quartz SiO2 (100). Thermal expansion mismatch during DWB causes fractures of LiNbO3. Also, LiNbO3 decomposes into Li2O5 and Li+ at T > 493K. Instead, this work uses Nano-BondingTM, 1 (NB) and Surface Energy Engineering to modify surface energies into ‘far-from-equilibrium’ states so that when nano-contacted, a 2D-precursor phase forms to catalyze bonding.
Three Liquid Contact Angle Analysis (3LCAA) can map different angular directions on 6” LiNbO3 (110), Si (100), and α-quartz SiO2 (100) wafers. Water contact angles are found to vary significantly, by 50%, from 41.8 ± 1.5° to 59.8 ± 1.5°, as a function of crystal direction. Correlation between surface structure and surface energies along different crystal directions will be discussed.
1 Herbots et al. US Pat. 6613677 (2003), 7,851,365 (2010), 9,018,077 (2015), 9,589,801 (2017), pend. (2020)
*SiO2 Innovates, LLC, Tempe, AZ 85282
AccuAngle Analytics, LLC, Tempe, AZ 85282
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Presenters
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Abbie Elison
- Physics, Arizona State University