UHV- direct bonding of semiconductor wafers at room temperature using hydrogen ion beam surface cleaning

摘要

A direct bonding of different materials with variously related crystallographic axes gives us extended possibilities for device integration. With this as our motivation, we further investigate and develop the UHV direct bonding technique for different semiconductor wafer materials as bonding partners, e.g. A~Ⅲ B~Ⅴ compound semiconductors among one other or with Si or Ge. Direct wafer bonding (DWB) was achieved by a bonding procedure inside an UHV apparatus at room temperature without external mechanical force to the wafers following the cleaning of the wafer surfaces by using 300 eV low energy hydrogen ion bombardment. Last step was a post-bonding annealing in UHV atmosphere for short time to enhance the bonding energy.rnThe interface between the bonded wafers was analyzed by infrared transmission images. A detailed analyzes of the interface structure was carried out by cross-sectional transmission electron microscopy (TEM). For the characterization of the hydrogen ion beam cleaning of the wafer surface XPS and AFM measurement have been performed.rnIn the present paper results on the DWB of GaAs and Ge will be presented.