Comparative Study of Surface Energy Engineering for low temperature wafer bonding on LiTaO$_{\mathrm{3}}$ and LiNbO$_{\mathrm{3}}$ to Si and SiO$_{\mathrm{2}}$

Surface engineering is needed to directly bond wafers of LiTaO$_{\mathrm{3}}$ (100) and LiNbO$_{\mathrm{3}}$ (100), Si (100) and SiO$_{\mathrm{2}}$ (100). Surface Energy Engineering (SEE) can be designed using the Van Oss-Chaudhury-Good for wafer mapping of three surface interactions, namely van der Waals interactions, and interactions with electron donors and acceptors. Three liquid contact angle analysis (3LCAA$^{\mathrm{TM}})$ was developed for Nanobonding$^{\mathrm{TM}}$ using several drops for each of liquids (Water, $\alpha $-bromo naphthalene, glycerin) for contact angle measurements. The DROP$^{\mathrm{TM}}$ algorithm is a fast, accurate way to extract contact angles. Surface engineered hydrophobic LiTaO$_{\mathrm{3\thinspace }}$(100) bonding to hydrophilic Si (100) is attempted for electron donor-acceptor low temperature direct bonding. Hydrophilic-hydrophilic hydrogen bonding at low temperature is found to require hydrophilic LiTaO$_{\mathrm{3}}$ and LiNbO$_{\mathrm{3}}$.