Experimental investigation and numerical simulation of glass-silicon bonding by localized laser heating

In this paper, we report a method to bond silicon and glass wafers directly using localized laser heating (pulsed Nd:YAG laser, 1064 nm, 12 ns). Laser energy was transmitted through the glass wafer and absorbed by the silicon wafer, resulting in a localized high temperature area. Pressure was applied upon the silicon and glass wafers to ensure immediate contact and good heat conduction between them. Scanning electron microscope (SEM) and chemical analysis were used to study bonding area and bonding mechanism. Numerical simulation was carried out in parallel using finite element method to predict the local temperature change of both the glass wafer and the silicon wafer during laser heating. The simulation was validated to some extent by the matching of melting time, which was obtained by using an additional probing laser (He-Ne, 633 nm, 20 mW) during the transient melting and re-solidification of the silicon. This bonding process is conducted locally while the entire wafer is maintained at room temperature, making it advantageous over traditional anodic bonding or fusion bonding.