High-yield fabrication method for high-frequency graphene devices using titanium sacrificial layers

The authors present a fabrication process for the development of high-frequency (>30 GHz) on-wafer graphene devices with the use of titanium sacrificial layers. Graphene patterning requires chemical processes that have deleterious effects on graphene resulting in very low yield. The authors prevent delamination of the delicate graphene from the substrate during the fabrication steps by depositing a blanketing 30 nm titanium layer at the beginning of the process. Additionally, titanium is a low cost, hazardless, and well-established material in the semiconductor industry and, therefore, constitutes an attractive solution for graphene protection. With the proposed blanketing approach, the authors obtain more than 90% device yield, allowing the development of graphene-based reconfigurable, large-area, high-frequency topologies such as antenna arrays. Without the use of this titanium sacrificial layer, they show that the expected yield plummets. In addition, they validate the proposed fabrication procedure through on-wafer measurements in the 220–330 GHz range.