RWTH Aachen University: 2D materials for mass production of electronic components

Two-dimensional materials have enormous potential to enable components with a significantly smaller size and extended functionality compared to today’s silicon technologies. To do this, however, 2D materials must be integrated into semiconductor production lines, which has been a difficult step so far. A team from Sweden and Germany now describes a method with which this can be achieved under the title “Large-area integration of two-dimensional materials and their heterostructures by wafer bonding” in the journal “Nature Communications”. Professor Max Lemme from the Chair of Electronic Components at RWTH Aachen University, the KTH Royal Institute of Technology in Stockholm, the University of the Federal Armed Forces in Munich, AMO GmbH and Protemics GmbH were involved in the research.

Currently, most of the experimental methods of transferring 2D materials from their growth substrate to the desired electronics are not compatible with mass production. In addition, they lead to a significant deterioration in the 2D material and its electronic properties. The new method uses bisbenzocyclobutene (BCB) and conventional wafer bonding devices. BCB is heated until it is viscous, then the 2D material is pressed against it. A stable connection is created between the 2D material and the wafer at room temperature. To stack materials, the heating and pressing steps are repeated.

The team demonstrates the transfer of graphene and molybdenum disulfide (MoS2), representing the transition metal dichalcogenides, and stacks graphene with hexagonal boron nitride (hBN) and MoS2 to form heterostructures. All transferred layers and heterostructures are of high quality, they have a uniform coverage over silicon wafers up to 100 millimeters in size and only showed low stress in the transferred 2D materials.

“In principle, the transfer method can be applied to any 2D material, regardless of the size and type of growth substrate,” says RWTH Professor Lemme from RWTH, who also heads AMO GmbH. He adds: “Since the method only uses tools and methods that are already common in the semiconductor industry, a new generation of components could quickly emerge in which 2D materials are integrated on conventional integrated circuits or microsystems. The range of possible applications is huge: from photonics and sensor technology to neuromorphic computing. “

The work of the scientists was carried out as part of the 2D Experimental Pilot Line (2D-EPL) project. This has been financed by the European Commission with 20 million euros since October 2020. The aim is to close the gap between the production on a laboratory scale and the large-scale production of electronic components based on two-dimensional materials.

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