King Abdullah University of Science and Technology (KAUST) has showcased, for the first time, a functional microchip integrating two-dimensional, atomically thin materials possessing exotic properties. This heralds a new epoch in microelectronics, marking a breakthrough that unveils the boundless potential of two-dimensional materials in expanding the realm of functional and performance capabilities within microchip technology.
Ever since the inception of atomically thin layers of graphene in 2004, scientists have been captivated by the extraordinary and promising physical properties of this material, fueling a fervent interest in advanced and innovative applications. However, despite two decades of research, the development of functional microdevices based on these two-dimensional materials has remained elusive due to the intricate challenges involved in fabricating and handling such delicate films.
Inspired by the recent accomplishments of the Lanza lab in functional 2D films, a collaborative effort led by KAUST has now successfully produced and demonstrated a prototype microchip based on two-dimensional materials.
“Our impetus lies in elevating the technological readiness level of electronic devices and circuits that leverage 2D materials, utilizing conventional silicon-based CMOS microcircuits as a foundation and standardized semiconductor manufacturing technology,” stated Lanza. “Nevertheless, the hurdle lies in the fact that synthesized 2D materials may contain local defects, such as atomic impurities, which can lead to minor device malfunctions. Furthermore, integrating 2D materials into microchips without causing damage has proven to be exceedingly challenging.” Capitalizing on the expertise of the research team, the chip’s design has been optimized, facilitating ease of manufacturing and mitigating the impact of defects. This was achieved by fabricating standard complementary metal-oxide semiconductor (CMOS) transistors on one side of the chip and routing interconnect lines to the lower side, where the 2D material could be safely transferred onto small pads measuring less than 0.25 microns in diameter.
“We synthesized a two-dimensional material, hexagonal boron nitride (h-BN), on copper foil and utilized a low-temperature wet method to transfer it onto a microchip, which was then layered on top through traditional vacuum evaporation and photolithography techniques. The electrode formation, a process that we have conducted in-house, completes the procedure,” explained Lanza. “In this manner, we generated a 5×5 array of single-transistor/single-memory cells, interconnected in a matrix of horizontal stripes.”
The remarkable property of 2D h-BN lies in its mere thickness of 18 atoms, equivalent to 6 nanometers, rendering it an ideal “memory” element. It exhibits resistive characteristics that can be regulated by an applied voltage. In this 5-by-5 format, each minuscule memory pad is connected to a dedicated transistor, ensuring precise voltage control and enabling the memory to function with superior performance and reliability over thousands of cycles, serving as a functional device. In this particular case, it operates as a low-power neural network element.
“With this groundbreaking achievement, we have initiated discussions with leading semiconductor companies to further advance our endeavors in this domain,” expressed Lanza. “Additionally, we are contemplating the installation of our own wafer-scale industrial processing system for 2D materials at KAUST to propel this capability forward.”