Recently, TSMC and Taiwan Jiaotong University successfully developed an ultra-thin two-dimensional semiconductor insulating material based on boron nitride, which is the world's thinnest and has a thickness of only 0.7 nanometers. It is expected to further develop chips of 2 nanometers or even 1 nanometer process. The results were published in the most recent issue of Nature.
Boron nitride (BN) is not a new material. It is important because it not only has a good heat dissipation effect, but also an excellent insulator. The existence of insulators is needed in advanced processes. The significance of their existence is usually to help electrons pass through the channels in the transistor. As the process continues down, the channels are bound to become smaller and smaller. Without a good insulator, the crosstalk between the transistors will be very large, which will cause the chip performance to be greatly reduced. When the manufacturing process is stepped into 3 nanometers, the oxide insulator materials used in the past 7 nanometers and 5 nanometers will no longer be suitable. The reason is that these oxide insulators are three-dimensional and it is easy for some charges to attach to them, making it difficult for current to pass .
Wafer-scale single-crystal hexagonal boron nitride monolayers on Cu (111)
Ultrathin two-dimensional (2D) semiconducting layered materials offer great potential for extending Moore's law of the number of transistors in an integrated circuit 1. One key challenge with 2D semiconductors is to avoid the formation of charge scattering and trap sites from adjacent dielectrics. An insulating van der Waals layer of hexagonal boron nitride (hBN) provides an excellent interface dielectric, efficiently reducing charge scattering2,3. Recent studies have shown the growth of single-crystal hBN films on molten gold surfaces4 or bulk copper foils5. However, the use of molten gold is not favoured by industry, owing to its high cost, cross-contamination and potential issues of process control and scalability. Copper foils might be suitable for roll-to-roll processes, but are unlikely to be compatible with advanced microelectronic fabrication on wafers. Thus, a reliable way of growing single-crystal hBN films directly on wafers would contribute to the broad adoption of 2D laye red materials in industry. Previous attempts to grow hBN monolayers on Cu (111) metals have failed to achieve mono-orientation, resulting in unwanted grain boundaries when the layers merge into films6,7. Growing single-crystal hBN on such high-symmetry surface planes as Cu (111) 5,8 is widely believed to be impossible, even in theory. Nonetheless, here we report the successful epitaxial growth of single-crystal hBN monolayers on a Cu (111) thin film across a two-inch c- plane sapphire wafer. This surprising result is corroborated by our first-principles calculations, suggesting that the epitaxial growth is enhanced by lateral docking of hBN to Cu (111) steps, ensuring the mono-orientation of hBN monolayers. The obtained single-crystal hBN , incorporated as an interface layer between molybdenum disulfide and hafnium dioxide in a bottom-gate configuration, enhanced the electrical performance of transistors. This reliable approach to producing wafer-scale single-crystal hBN paves the way to future 2D electronics.