The most commonly used semiconductor wafer bonding techniques are direct bonding, anodic
bonding, adhesive bonding, low-temperature melting glass bonding, solder bonding, eutectic bonding,
thermocompression bonding and ultrasonic bonding. The basic principle that all bonding techniques
have in common is that two materials fuse and adhere to each other if they are brought in sufficiently
close contact. The cohesion of atoms and molecules in a solid material as well as the cohesion of
atoms and molecules between two solid materials is ensured by a number of basic bond types, which
are: