Wafer bonding is a packaging technology for MEMS, NEMS, and optoelectronics. It connects two or more micro components, like Si wafer and III-V compound semiconductors. It aims to create closed adaptable channels, composite 3D structures, and cavities. Bonding also gives mechanical strength, provides electrical contact, and creates thermal coupling. In this article, we will discuss the different bonding methods at the wafer-level.
Silicon direct bonding is the process of connecting a Si wafer with another micro component through thermal action. It also occurs due to molecular interactions. Silicon is widely used for medical and chemical applications.
Plasma-stimulated surfaces create irreversible bonding because its condensation reaction creates covalent siloxane bonds. This method precisely bonds low-temperature surfaces. The plasma gets rid of impurities and generates Si-OH groups to create hydrophilic surfaces. It improves surface viscous flow and diffusion of water at the junction.
This method of wafer bonding is also known as diffusion bonding or solid-state welding. It bonds two metals together using heat and force simultaneously. Because of the atomic motion, diffusion needs atomic contact between surfaces. It allows atoms to travel from one crystal lattice to another based on crystal lattice vibration.
Glass frit bonding is also known as glass soldering. It is a wafer bonding technique that uses an intermediate glass layer to bond micro components. This method has high bonding strength, so it provides outstanding sealing.
There are several other wafer bonding methods aside from the four mentioned above. To learn more, contact our experts here at Wafer World.