Pseudoepitaxial transrotational structures in 14 nm-thick NiSi layers on [001] silicon

TL;DR

This study reveals that ultra-thin NiSi layers can adapt their structure through transrotational domains to maintain stability and improve electrical properties, impacting the scaling of electronic device metallizations.

Contribution

It demonstrates that 14 nm NiSi layers can form transrotational domains, enabling 3D lattice adaptation and enhanced stability despite orthorhombic structure.

Findings

14 nm NiSi layers form transrotational domains.

Transrotational domains improve stability and electrical performance.

Thinner NiSi layers maintain structural integrity without roughening.

Abstract

In a system consisting of two different lattices, the structural stability is ensured when an epitaxial relationship occurs between them and allows the system to retain the stress, avoiding the formation of a polycristalline film. The phenomenon occurs if the film thickness does not exceed a critical value. Here we show that, in spite of its orthorombic structure, a 14nm-thick NiSi layer can three-dimensionally (3D) adapt to the cubic Si lattice by forming transrotational domains. Each domain arises by the continuous bending of the NiSi lattice, maintaining a close relationship with the substrate structure. The presence of transrotational domains does not cause a roughening of the layer but instead it improves the structural and electrical stability of the silicide in comparison with a 24nm-thick layer formed using the same annealing process. These results have relevant implications on thickness scaling of NiSi layers currently used as metallizations of electronic devices.