Wafer bonding: A retrospective

Wafer bonding has become well-known and widely used as the process of adhesion of two flat mirror-polished wafers without the use of any intermediate adhesive layer. Today, it is used as a versatile tool in a wide variety of scientific fields and the technique has reach industrial maturity in particular for the manufacturing of Silicon-On-Insulator (SOI) materials, but also in other fields, such as for sensors, microsystems, optics and photonics. The early development of wafer bonding is reviewed and a retrospective view is taken on wafer bonding, addressing some of the critical research achievements and breakthroughs over the last three decades. The focus is limited to wafer bonding without the use of adhesive layers or electrostatic fields, and will hence not discuss related techniques, such as anodic bonding