Room-temperature wafer bonding of LiNbO₃ and SiO₂ using a modified surface activated bonding method

Abstract

In this paper, we report room-temperature bonding of LiNbO3 (LN) and SiO2/Si for the realization of a LN on insulator (LNOI)/Si hybrid wafer. We investigate the applicability of a modified surface activated bonding (SAB) method for the direct bonding of LN and a thermally grown SiO2 layer. The modified SAB method using ion beam bombardment demonstrates the room-temperature wafer bonding of LN and SiO2. The bonded wafer was successfully cut into 0.5 × 0.5 mm2 dies without interfacial debonding owing to the applied stress during dicing. In addition, the surface energy of the bonded wafer was estimated to be approximately 1.8 J/m2 using the crack opening method. These results indicate that a strong bond strength can be achieved, which may be sufficient for device applications.

Residual Stress in Lithium Niobate Film Layer of LNOI/Si Hybrid Wafer Fabricated Using Low-Temperature Bonding Method

“…As shown, we could observe an approximately 4-nm-thick uniform intermediate layer, which was formed during surface activation and low-temperature annealing processes. Per previous research [ 24 ], the thickness of the Fe-containing layer deposited under this condition had a thickness of a few nanometers. The diffusion created by this low-temperature annealing process may have enhanced the bond strength between LN and SiO 2.…”

“…To date, this modified SAB demonstrated room temperature bonding of LN-Si, SiO 2 -SiO 2 , and SiO 2 -SiN. We applied this method using an ultrathin film of Fe to room temperature bonding of LN and SiO 2 to minimize the propagation loss through a LNOI waveguide due to large absorption of Fe [23,24]. However, it is difficult to obtain sufficient bond strength at room temperature to withstand the above-mentioned post-bond wafer-thinning processing.…”

Progress in wafer bonding technology towards MEMS, high-power electronics, optoelectronics, and optofluidics

“…[96] (m) SEM image of the bonded LNOI waveguide. [97] consists of a slab and a strip superimposed onto it, as shown in Figure 5(a). Single-mode operation at the wavelengths of 635 nm, 850 nm, and 1550 nm can be achieved by adjusting the structural parameters.…”

Asymmetric Line Shape of Near-field Luminescence Spectrum Induced by Stress in Al2O3

“…Our finding provides important insight into the near-field-based piezospectroscopy and its application to the stress generation area of structural components, such as the bonded interface of dissimilar materials. (14)(15)(16)…”