2D Materials for the Large-Scale Production of Electronic Components

Paper by international research team published in Nature Communications.

 

Two-dimensional (2D) materials have a huge potential for providing devices with much smaller size and extended functionalities with respect to what can be achieved with today’s silicon technologies. But to exploit this potential, 2D materials will have to be integrated into semiconductor manufacturing lines – a notoriously difficult step.

A team of researchers from Sweden and Germany now reports a new method to make this work. Their paper, entilted “Large-area integration of two-dimensional materials and their heterostructures by wafer bonding,” has now been published in the journal Nature Communications. Professor Max Lemme, Chair of Electric Devices at RWTH Aachen University, KTH Royal Institute of Technology in Stockholm, Universität der Bundeswehr München, AMO GmbH, and Protemics GmbH have collaborated in the research project.

So far, most of the experimental methods for transferring 2D materials from their growth substrate to the desired electronics are either non-compatible with high-volume manufacturing or lead to a significant degradation of the 2D material and of its electronic properties. The solution proposed by the international research team uses a standard dielectric material called bisbenzocyclobutene (BCB) along with conventional wafer bonding equipment. A resin made of BCB is heated until it becomes viscous; then, the 2D material is pressed against it. At room temperature, the resin becomes solid and forms a stable connection between the 2D material and the wafer. To stack materials, the steps of heating and pressing are repeated.

The researchers demonstrated the transfer of graphene and molybdenum disulfide (MoS2), as a representative for transition metal dichalcogenides, and stacked graphene with hexagonal boron nitride (hBN) and MoS2 to heterostructures. All transferred layers and heterostructures were reportedly of high quality, that is, they featured uniform coverage over up to 100-millimeter sized silicon wafers and exhibited little strain in the transferred 2D materials.

“Our transfer method is in principle applicable to any 2D material, independent of the size and the type of growth substrate”, says RWTH professor Max Lemme, who is also managing director of AMO GmbH. “And, since it only relies on tools and methods that are already common in the semiconductor industry, it could substantially accelerate market entry of a new generation of devices where 2D materials are integrated on top of conventional integrated circuits or microsystem. There is a wide range of potential applications, from photonics, to sensing, to neuromorphic computing.

The research activities were conducted as part of the Graphene Flagship’s 2D Experimental Pilot Line (2D-EPL), which has received funding of 20 million from the European Commission. The aims of the project is to bride the gap between lab-scale manufacturing and large volume production of electronic devices based on two-dimensional materials.