Plasma Enhanced Atomic Layer Deposition of Plasmonic TiN Ultrathin Films Using TDMATi and NH3

Katherine Hansen,Chen Yang,Amartya Dutta,Melissa Cardona

doi:10.3390/ma13051058

Abstract

Transition metal nitrides, like titanium nitride (TiN), are promising alternative plasmonic materials. Here we demonstrate a low temperature plasma-enhanced atomic layer deposition (PE-ALD) of non-stoichiometric TiN0.71 on lattice-matched and -mismatched substrates. The TiN was found to be optically metallic for both thick (42 nm) and thin (11 nm) films on MgO and Si <100> substrates, with visible light plasmon resonances in the range of 550–650 nm. We also demonstrate that a hydrogen plasma post-deposition treatment improves the metallic quality of the ultrathin films on both substrates, increasing the ε1 slope by 1.3 times on MgO and by 2 times on Si (100), to be similar to that of thicker, more metallic films. In addition, this post-deposition was found to tune the plasmonic properties of the films, resulting in a blue-shift in the plasmon resonance of 44 nm on a silicon substrate and 59 nm on MgO.

Highlights

While the majority of plasmonics research has focused on noble metals, such as gold and silver, today there is a need to replace these traditional materials with alternatives to make commercially-viable plasmonic devices [1,2,3]
Raman spectroscopy, performed on a film grown by 400 ALD cycles on an magnesiumoxide oxide (MgO) substrate (Figure 1a), confirms titanium nitride (TiN)
Our work aims at investigation of the effect of the analysis by X-ray photoelectron spectroscopy (XPS) of a post-deposition hydrogen plasma treated sample hydrogen Compositional plasma treatment on the optical properties of ultrathin TiN thin films (11 nm)

Summary

Introduction

While the majority of plasmonics research has focused on noble metals, such as gold and silver, today there is a need to replace these traditional materials with alternatives to make commercially-viable plasmonic devices [1,2,3]. Transition metal nitrides, like titanium nitride (TiN), have proven to be promising due to their real permittivity values comparable to that of traditional metals in the visible range, and tunable optical properties by varying the processing methods and/or variables [4]. Transition metal nitrides possess many promising physical properties, such as high thermal stabilities, high melting points, and compatibility with a wide number of substrate materials. Transition metal nitrides can be fabricated and integrated more into silicon-based devices without the concern of volume expansion and stress at the silicon-plasmonic material interface due to diffusion, as is common with Au due to its low eutectic temperature [5].

Methods

Results

Conclusion