Amorphous Boron Nitride Discovered with Potential Use in Chips

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Since the discovery of graphene, there has been an intense effort to find more 2D materials. Graphene itself is an atom-thick sheet of carbon atoms in a hexagonal pattern and has many interesting and valuable properties, including great strength, flexibility, and conductivity. Because of these characteristics, efforts are being made to find ways to apply it in electronics, but the fact it is such an effective conductor is a problem in some situations. Modern electronics are based on semiconductors after all, so designing a graphene transistor is trickier. However, various other 2D materials have been discovered, including hexagonal boron nitride, so-called white graphene that is in fact a semiconductor.

Hexagonal boron nitride (h-BN) is similar to graphene by also having a hexagonal lattice structure and being one atom thick, but it is comprised of boron and nitrogen atoms. That it is a natural semiconductor has made it a target of great interest and now researchers at the Samsung Advanced Institute of Technology (SAIT), Ulsan National Institute of Science and Technology (UNIST), and the University of Cambridge have discovered amorphous BN (a-BN). Though still comprised of boron and nitrogen, a-BN has an amorphous molecule structure, setting it apart from white graphene. What makes it so special is its ultra-low dielectric constant of 1.78, coupled with its strong electrical and mechanical properties. By having such a low dielectric constant, it has potential to serve as an interconnect isolation material, by minimizing electrical interference. The interconnects in a chip are the metal wires that connect the different components, which is why it is important to reduce interference between them with better insulators or with greater distance between them.

With a dielectric constant of 1.78, a-BN comes in 30% lower than that of other insulators currently available. Importantly, it can also be produced at a relatively low temperature of 400 ºC, which is the same temperature SAIT notes is the upper temperature limit for enhancing compatibility with graphene in silicon-based semiconductor processes. At that temperature, an ideal a-BN film was deposited on a silicon substrate that was just 3 nm thick.

Besides demonstrating an ultra-low dielectric constant, a-BN also has a high breakdown voltage, which is the voltage at which point a dielectric will start breaking down. This then can produce conductive connections between the two charge carrying components the dielectric had been insulating from each other.

Thanks to its desirable properties, Samsung notes amorphous boron nitride can be expected to be applied to such semiconductors as DRAM and NAND, as well as next generation memory solutions for large-scale servers. It will be interesting to see the ways this may come to be deployed, as well as any other 2D materials with their interesting and unusual properties. It will take time though, as finding ways to produce wafer-scale samples that can then be effectively integrated into semiconductor manufacturing processes is difficult. Samsung Advanced Institute of Technology has been working that though, with some recent achievements in producing wafer-scale, single-crystal samples as well as the development of a graphene transistor.

Source: Samsung and UNIST

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