Surface-initiated growth of copper using isonicotinic acid-functionalized aluminum oxide surfaces

Cathren E Gowenlock,James D Mcgettrick,Virginia Gomez,Enrico Andreoli,Andrew R Barron

doi:10.1007/s11998-016-9842-0

Abstract

Isonicotinate self-assembled monolayers (SAM) were prepared on alumina surfaces (A) using isonicotinic acid (iNA). These functionalized layers (iNA-A) were used for the seeded growth of copper films (Cu-iNA-A) by hydrazine hydrate-initiated electroless deposition. The films were characterized by scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and advancing contact angle measurements. The films are Cu0 but with surface oxidation, and show a faceted morphology, which is more textured (Rq = 460 ± 90 nm) compared to the SAM (Rq = 2.8 ± 0.5 nm). In contrast, growth of copper films by SnCl2/PdCl2 catalyzed electroless deposition, using formaldehyde (CH2O) as the reducing agent, shows a nodular morphology on top of a relatively smooth surface. No copper films are observed in the absence of the isonicotinate SAM. The binding of Cu2+ to the iNA is proposed to facilitate reduction to Cu0 and create the seed for subsequent growth. The films show good adhesion to the functionalized surface.

Highlights

As a thin film deposition method, electroless deposition (ELD) is relatively simple and less expensive, is performed at ambient or low temperature, and can be potentially selective.[1,2] In comparison with electrochemical deposition, ELD occurs via chemically promoted reduction of metal ions without external current and is suitable for a wide range of substrates, including insulators
Catechols, and thiols have all been used to seed metallic ELD copper growth on surfaces,[10,11,12] and they can be used to assist in electrochemical deposition.[13]
We have recently reported that isonicotinic acid (Fig. 1) functionalization of alumina nanoparticles allows for the highly stable binding of copper acetate (Cu2(O2CMe)4),[22] and we have shown that its derivatives allow for binding of metals to specific locations on nanoparticles.[23]

Summary

Introduction

As a thin film deposition method, electroless deposition (ELD) is relatively simple and less expensive, is performed at ambient or low temperature, and can be potentially selective.[1,2] In comparison with electrochemical deposition, ELD occurs via chemically promoted reduction of metal ions without external current and is suitable for a wide range of substrates, including insulators. Self-assembled monolayers (SAMs) with varying functionalities have been demonstrated to direct the assembly of inorganic thin films via ELD.[7,8,9] The reason for this selective deposition is that the functionality of the SAM acts as an accelerator molecule to control crystal heterogeneous nucleation and growth. The use of the acid form allows for the covalent binding to the aluminum oxide surface,[24,25,26,27] and we have investigated the ability of isonicotinic acid-functionalized alumina thin films to promote the ELD of copper with

Methods

Results

Conclusion