Realizing unique 2D materials through confined reactions for electronics application

Ya-Ping Hsieh^1*

¹Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Ya-Ping Hsieh, email:yphsieh@gate.sinica.edu.tw

This talk introduces our recent research on new 2D materials synthesized by confined CVD and their application, with a focus on semiconductor fabrication processes. Photolithography is a key obstacle to increasing the density of electronic devices.
We have discovered that bilayer graphene could turn into fluorographene/graphene stacks when exposed to CF4 plasma, which exhibits near-ideal etch selectivity in silicon dry-etching processes.[1] Based on this advance, bilayer graphene was adopted as a hard mask for photolithographical patterning of semiconductors. The atomic thickness of our hard mask can improve the achievable resolution of the resulting pattern and we demonstrated nanometer-scale resolution of the bilayer graphene mask in a double patterning process. [2]
Moreover, we utilized graphene's natural wrinkles to pattern transfer such nanostructures to transition metal dichalcogenides (TMDCs). This subtractive pattern transfer process allows us to fabricate TMDC nanoribbons with an aspect ratio of up to 7000 and nanometer-width with unprecedented density. This research opens up new possibilities for creating nanostructures with greater precision using 2D materials.
To extend our findings towards commercially significant reactive ion etching processes, we require a 2D material with higher hardness and chemical inertness than graphene. I will introduce the appeal of two-dimensional tungsten nitrides (W5N6) for this purpose.[3]We demonstrate the first successful synthesis of W5N6, an ultrahard semimetal[4] which could provide a new route towards a 2D hard mask for improved efficiency and accuracy of the lithography.

Keywords: 2D materials, MXene, CVD, Hard mask