On a quest to unlock the growth of high mobility two-dimensional materials through atomic layer deposition

Novel two-dimensional materials, and especially semi-conducting transition metal dichalcogenides (MX₂, with M being a transition metal and X a chalcogen) offer advanced functionality in complex and ultra-scaled integrated systems. In view of their compelling electronic and electrical performance as an atomically thin monolayer, imec explores their integration for various applications and systems, in particular for advanced CMOS and memory technologies in a beyond silicon roadmap. The deposition of high-quality materials is highly challenging due to the high aspect ratio requirements of advanced 3D architectures. Atomic Layer Deposition (ALD) is a promising technique in this respect, as it can in principle enable conformal deposition on 3D structures with a thickness and composition control at the atomic level [1,2,3].

However, several key aspects of the MX₂ growth need to be understood in order to unlock the conformal deposition of high mobility transition metal dichalcogenides. These include identifying suitable chemical precursors, understanding the MX₂ growth mechanism, and quantifying how the deposition chemistry and applied surface pretreatments affect the electrical performance of the MX₂ material. 

In this project, the Ph.D. candidate will contribute to an international effort that blends modelling insights, chemical precursor design, and on-scale demonstration to address these growth and material challenges. She/he will perform her/his Ph.D. research at the Plasma and Materials Processing group of the Eindhoven University of Technology (TU/e, The Netherlands), in close collaboration with the MX₂ growth team at imec. The candidate will explore and quantify how different inhibiting surface treatments can be exploited to control the nucleation of MX₂ materials during ALD. Different complementary characterization techniques will be combined to provide understanding of the nucleation mechanism during ALD. The insight will be used to boost the electrical performance of the deposited film. The semiconductor properties and conformality will be investigated on nanoscale patterned structures.

Uniquely, the Ph.D. candidate will conduct the research partly at TU/e and imec. As such, the project will leverage the NanoLab@TU/e facilities with both the imec 300mm production and atomistic modelling platforms for advanced node CMOS technologies, enabling the candidate to identify novel deposition chemistries and to grow conformal MX₂ films on patterned structures with topography and dimensions down to tens of nanometers.

[1] M. Mattinen et al., Adv. Mater. Interfaces 2021, 8, 2001677​

[2] S. Balasubramanyam et al., ACS Appl. Mater. Interfaces 2020, 12, 3, 3873–3885

[3] B. Groven et al., Chem. Mater. 2018, 30, 21, 7648–7663