Structure of a bismuth crystal showing the regular structure; focus stacking on black
Taiwan Semiconductor Manufacturing Co.(TSMC), Massachusetts Institute of Technology(MIT), and National Taiwan University(NTU) have jointly discovered advanced beyond-silicon electronic technology that is key to breakthrough 1nm, increasing chip efficiency and continuing Moore’s Law, which came just after IBM announced the world’s first 2nm chipmaking technology breakthrough, pushing the limit of silicon electronic technology.
1nm: Beyond silicon electronic technology
As the current semiconductor design and process using silicon approach 5nm and 3nm nodes, the number of transistors piled on a chip is also nearing physical limitations. The atomically thin two-dimensional semiconductors have long been given hope for realizing high-performance electronic devices and breaking through current limitations in downscaling.
However, high contact resistance and poor current delivery capability are critical and unresolved issues that have hindered the improvement of two-dimensional semiconductor transistors.
Overcoming 2D semiconductor limitations
These issues are addressed in a joint research published in Nature. The MIT research group found that with Bi electrodes, the two-dimensional materials contact resistance is vastly decreased, and the current transfer is increased.
TSMC’s Corporate Research optimized the chemical vapor deposition(CVD) process of Bi, and using the helium-ion beam lithography, the NTU research group shrank the channel material to a nanoscale, approaching the quantum limit.
Pushing solid semiconductor materials to the limits
One of the main researchers, Dr. Pin-Chun Shen, commented that in the past, semiconductors adopt three-dimensional materials, and their physical characteristics and component structure have achieved 3nm node technology. Downscaling the semiconductor to reach below 1nm, equivalent to roughly 1 to 3 atomic layers, has shown feasibility in this research via two-dimensional materials, further pushing solid semiconductor materials to the limit.
He further commented that the energy barrier formed between the metal electrode and the two-dimensional semiconductor interface can become negligible, if not eliminated, with the characteristics of the semimetal(Bi). The two-dimensional atomic structure also remains undamaged during the semimetallic Bismuth deposition.
This technology unveils the potential of high-performance monolayer transistors that are on par with state-of-the-art three-dimensional semiconductors, enabling further device downscaling. If the research could be commercialized in the future, it will be calling a new generation to the semiconductor industry.