M.Sc Thesis

M.Sc StudentKornblum Noga
SubjectSelective Metals Deposition by Atomic Layer Deposition Using
Low-Coordination Surface Sites
DepartmentDepartment of Materials Science and Engineering
Supervisor PROF. Boaz Pokroy
Full Thesis textFull thesis text - English Version


Area selective atomic layer deposition (AS-ALD) is an evolving field for nanopatterning, offering potential fabrication capabilities mainly for future microelectronics. Current AS-ALD potential methods rely mostly on the use of surface chemical modification, such as polymeric coatings, polymeric self-assembly, etching, ion implantation or self-assembled monolayers. While some of these methods have shown significant promise, they still do not provide a concert and realizable applicable solution. In this research, we propose an alternative approach to these self-assembly methods, by demonstrating selective deposition on terraced surfaces.

Bottom-up patterning of various materials using terraced surfaces have been demonstrated in many studies,but works examining their abilities to guide depositions conducted by atomic layer deposition are scarce. In this work we aimed to achieve selective deposition of metals on low-coordination surface sites on terraced sapphire surfaces, and specifically on step ledges.

To this end, ALD deposition processes of metallic nickel and platinum were developed and characterized. GIXRD, XRR, TM-AFM and XPS were used to characterize and study such layers, which led us to choose platinum as a case study for selective deposition rather than the former. Platinum deposition was investigated on (1 1 -2 0) A-oriented and (0 0 0 1) C-oriented terraced sapphire surfaces.

Selective deposition of platinum on A-sapphire surfaces was demonstrated and the selectivity mechanisms were addressed. The selective deposition exhibited a preferential deposition on S-plane ledges and in concave kinks. A possible link of deposition selectivity to the surface miscut angle was identified. While further investigation into the mechanisms is in need, this finding highlights the potential of AS-ALD based on surface-energetics.