ZoneBOND™ Thin Wafer Support Process for Wafer Bonding Applications

Abstract

Wafer-to-wafer bonding is widely used to support both the production of integrated circuits and MEMS devices. Bonding may be accomplished in a variety of ways including anodic, thermal compression, and adhesive bonding. The bond may be either permanent or temporary. Permanent wafer bonding is used to combine two materials together that remain together for the life of the device, for example, in the production of Si/GaAs wafer heterostructures for integration of an optoelectronic device into silicon integrated circuit technology. Temporary bonding is used to support the device wafer during certain processing steps, and then removed once the device wafer is completed. Currently, there are several temporary bonding processes being developed in industry. The leading technology utilizes some form of polymeric material to temporarily fasten or bond a rigid backing material, usually silicon or glass, to the device wafer for processing. The main issues associated with these techniques are temperature stability of the adhesive, removal from the support wafer, and cleaning the adhesive from the device wafer. The ideal process would require bonding at an acceptable temperature (usually less than 200°C), surviving through higher temperature processes, followed by debonding at lower temperature or even room temperature. In this paper, an alternative solution is reported that utilizes current thermoplastic adhesives and silicon support wafers coupled with a patented technology, developed by Brewer Science, Inc. Support wafers are bonded to device wafers at acceptable temperatures, mechanical integrity is maintained through semiconductor or MEMs processing, and the completely processed device wafer is then safely debonded from the support wafer at room temperature.