Chinese scientists have developed the world’s most complex two-dimensional (2D) semiconductor microprocessor, with the chip set to enter pilot-scale production. Details of the chip, which is less than one nanometer thick, were published in the peer-reviewed journal Nature. Its most notable advance is that fabrication of the chip does not relies on advanced extreme ultraviolet (EUV) lithography, opening a new, independent pathway for China in semiconductor innovation. As silicon-based integrated circuits approach the physical limits of miniaturization, researchers worldwide have turned to 2D materials, such as molybdenum disulphide and tungsten diselenide, to push the boundaries of chip performance. Typically only one atom thick, these materials offer remarkable physical properties, enabling further scaling and improved functionality in next-generation circuits.
Although wafer-scale growth of 2D materials has been achieved over the past decade, until now the most complex 2D semiconductor digital circuit – developed by the Vienna University of Technology in 2017 – contained just 115 transistors, “because carving the same object out of tofu is far harder than carving it from jade,” Fudan University Professor Bao Wenzhong said, describing the fragility and challenges of using 2D semiconductors compared with traditional silicon in chip manufacturing. After five years of development, Bao, along with Professor Zhou Peng from Fudan University’s National Key Laboratory of Integrated Circuits and Systems and their team, built a 32-bit RISC-V microprocessor named Wuji, incorporating 5,900 transistors and measuring less than 1nm thick. This achievement represents a new global benchmark in 2D semiconductor integration.
The key to the more than 50-fold increase in the chip’s integration level lies in the team’s ability to maintain both precision and uniformity at the atomic scale – crucial for high manufacturing yields. “For example, inverter circuits are basic building blocks of chips, and how well they work shows the chip’s overall quality,” Zhou said. “The inverters we made with 2D materials performed really well – they had strong signal output and very low energy loss when turned off, which is a big step forward in engineering.” The team fabricated a 30 x 30 array of inverters – 900 in total – and testing showed that 898 functioned correctly, achieving a record yield of 99.77%. The circuits exhibited superior switching voltage and consistency compared to similar studies. The fabrication of Wuji involved highly complex processes, some of which were optimized with the help of artificial intelligence (AI).
“By using domestically developed semiconductor equipment and the open-source RISC-V framework – without relying on EUV lithography – and by creating a full-stack 2D integration process, we’ve laid the foundation for a new, self-reliant development path for China’s chip industry,” Zhou stressed, as reported by the the South China Morning Post.
Chinese scientists have also created the world’s largest N-polar gallium nitride (GaN) wafer, at 20.3 cm, which could slash production costs by 40%. GaN has been hailed as a flagship third-generation compound semiconductor. It is revolutionizing high-frequency, high-power applications including 5G/6G networks, satellite communications, autonomous vehicles and radar systems, due to its exceptional physical properties, the Global Times adds.
