Creating Advanced gate stacks for 2D semiconductor devices

A first objective of this PhD project is to study new materials and new process strategies, beyond conventional ALD, for forming the interface layer and the gate dielectric on 2D channels and the impact on dielectric properties and transport. We will first investigate the impact of several amorphous and 2D dielectric materials on the transport properties into the channel using back gate architecture, in collaboration with device team. Based on the results, we will select the most promising materials for further investigation. Next, we will investigate the growth mechanism during deposition on a 2D semiconductor surface, and investigate how it affects the layer closure and structure of the resulting interface. The initial growth mechanism is governed by a complex interplay of processes, including physisorption, chemisorption, diffusion, aggregation, and possibly crystallization [3,4]. Information about the growth evolution comes from an extensive set of characterization techniques available in the imec labs and facilities. The properties of the selected deposited dielectric layers, the resulting interface with the 2D semiconductor and its performance in electrical devices will be tested in collaboration with the beyond CMOS device team at imec.

A second research objective is to identify and address some of the specific material and deposition technological and scientific challenges at small scale, in view of forming ultimately the gate dielectric at the dimension of sub 10 nm device. Specific attention will go to the opportunities offered by area-selective deposition techniques with 2D materials and the gate stack realm.

[2] B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti, A. Kis, Nature Nanotechnology, 6, 147 (2011).

[3] J. Soethoudt, F. Grillo, E. A. Marques, J. R. van Ommen, Y. Tomczak, L. Nyns, S. van Elshocht, A. Delabie, Advanced Materials Interfaces, 5, 1800870 (2018)

[4] H. Zhang, G. Arutchelvan, J. Meersschaut, A. Gaur, T. Conard, H. Bender, D. Lin, I. Asselberghs, M. Heyns, I. Radu, W. Vandervorst, A. Delabie, Chemistry of Materials, 2017, 29, 6772.