China Takes Chips Beyond Silicon — 32-Bit RISC-V Processor Built on Atomic-Thin Semiconductor

This week, Chinese scientists published a paper in Nature reporting that they have gone beyond silicon in chip manufacturing. A full-fledged 32-bit RISC-V processor was manufactured on a single-molecule-thick semiconductor layer—no more than 1 nm. But most importantly, the production does not require EUV scanners and is made using lithography equipment available to China.

Image source: Nature 2025

For about 20 years, researchers have been studying graphene as a material that can take the production of microchips to a new level of productivity and efficiency. However, graphene in its pure form is a conductor. Making transistors with it, for example using nanotubes, is almost like cooking the proverbial porridge from an axe: many other ingredients and processes are needed. The problem could be solved by an atomically thin semiconductor, but such have not yet been discovered. However, a number of semiconductor molecules can be located in a thin layer close to the thickness of individual atoms. One such molecule is molybdenum disulfide (MoS₂). Due to the hexagonal molecular structure, the MoS₂ layer is no thicker than 1 nm.

Scientists at Fudan University’s National Laboratory of Integrated Circuits and Systems have spent about five years developing processes using molybdenum disulfide, including vapor-depositing the material onto wafers. They are reported to have at least learned how to deposit MoS₂ layers onto sapphire wafers, on which they have begun to fabricate functioning atomically thin circuits. About 70% of the equipment for manufacturing chips on MoS₂ layers is borrowed from conventional silicon wafer manufacturing, meaning that the process developed by the scientists can be put into production with relatively modest upgrade costs.

Ultimately, the researchers created a 30 x 30 inverter array. In doing so, they circumvented the limitations of MoS₂, which only allows transistors of one conductivity, the n-type. MoS₂ molecules cannot be doped to create transistors with a different conductivity than the original material allows. Therefore, the gate voltages were determined by the conductors underneath them. In particular, aluminum and gold contacts were used.

Based on the manufactured inverters, scientists were able to assemble electronic circuits from a basic set of 25 electronic components. The overall circuit contained 5900 working transistors. Their frequency was low – several kilohertz. However, the Wuji chip executed the entire spectrum of 32-bit RISC-V instructions. This is the largest processor in history on an atomically thin semiconductor, the developers assure. And this is the first serious step beyond silicon electronics.