Copper Oxide ALD from a Cu(I) <beta>-Diketonate: Detailed Growth Studies on SiO₂ and TaN

Abstract

The atomic layer deposition (ALD) of copper oxide films from [(nBu3P)2Cu(acac)] and wet oxygen on SiO2 and TaN has been studied in detail by spectroscopic ellipsometry and atomic force microscopy. The results suggest island growth on SiO2, along with a strong variation of the optical properties of the films in the early stages of the growth and signs of quantum confinement, typical for nanocrystals. In addition, differences both in growth behavior and film properties appear on dry and wet thermal SiO2. Electron diffraction together with transmission electron microscopy shows that nanocrystalline Cu2O with crystallites &lt; 5 nm is formed, while upon prolonged electron irradiation the films decompose and metallic copper crystallites of ~ 10 nm precipitate. On TaN, the films grow in a linear, layer-by-layer manner, reproducing the initial substrate roughness. Saturated growth obtained at 120{degree sign}C on TaN as well as dry and wet SiO2 indicates well-established ALD growth regimes.

Analyzing Interface Recombination in Lead‐Halide Perovskite Solar Cells with Organic and Inorganic Hole‐Transport Layers

“…An alternative to NiO x could be an extremely thin layer of CuO x , which has been proposed in several publications. [ 26,33–42 ] A particularly promising result was published by Rao et al [ 26 ] who demonstrated CuO x ‐based MAPI solar cells with an efficiency of 19%. In this work, we therefore investigate CuO x as an alternative to the organic molecule PTAA to better understand the interface‐recombination losses in our devices.…”

Thermal Chemistry of Cu(I)-Iminopyrrolidinate and Cu(I)-Guanidinate Atomic Layer Deposition (ALD) Precursors on Ni(110) Single-Crystal Surfaces

“…ALD is already being used to deposit high-dielectric metal oxide thin films, and it has also shown great promise for the growth of electrical interconnects between nanometer-sized devices. , As the width of interconnect lines shrink, there is a need to replace aluminum for copper, to lower resistivity and improve electromigration resistance, − and current methods for growing copper films require the formation of a seed layer to be able to carry out further electrochemical deposition. , The fact that the seed Cu layer must be grown conformally points to the choice of ALD for this process; however, to date, there are no chemistry-based deposition methods that result in copper films with acceptable adhesion to the surface. Many copper precursors have been designed for CVD and ALD, including compounds with alkoxide, cyclopentadienyl, carboxylate, oxalate, , and acetonate − ligands, but most of those require high temperatures, leading to non-self-limiting deposition, possible precursor self-decomposition, and the agglomeration of the deposited copper. New β-ketiminates, β-diketiminates, amino-oxides, and similar N- and/or O-bidentate coordinated compounds have recently been shown to perform better, − but their full implementation in ALD processes has still not been accomplished.…”

Synthesis of β‐Ketoiminato Copper(II) Complexes and Their Use in Copper Deposition

“…media, [15] solar cells, [16] sensors, [17] batteries, [18,19] and catalysis. [20][21][22] For the formation of copper and copper oxides several methods have been applied including electrochemical deposition, [23,24] thermal oxidation of copper, [25] magnetron sputtering, [26] spin-coating, [27][28][29][30][31] chemical beam epitaxy (CBE), [32] atomic layer deposition (ALD) [6,[33][34][35][36][37] and chemical vapor deposition (CVD). [8,10,[38][39][40] For the vacuum-based deposition of copper or copper oxide films the precursors can be classified in two groups: Copper(I) and copper(II) compounds, respectively.…”

“…For the formation of copper and copper oxides several methods have been applied including electrochemical deposition,, thermal oxidation of copper, magnetron sputtering, spin‐coating, chemical beam epitaxy (CBE), atomic layer deposition (ALD), and chemical vapor deposition (CVD) , , …”

“…[41][42][43] Beneficial for copper(I) complexes is their ability to deposit pure copper films at low temperature (Ͻ200°C) usually without addition of any reducing agents. [41] Representatives are copper(I) β-diketonates (for example, [Cu(η 2 -H 2 C=CHSiMe 3 )(hfac)], [44] hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; [(R 3 P) 2 Cu(acac)], R = nBu, [6,34,37] OMe, [45] Et, [45] acac = acetylacetonate), alkoxides (i.e., [Cu(OtBu)] 4 [38] ), and carboxylates ([((RO) 3 P) m CuO 2 CCF 3 ], [39] R = Me, Et, CH 2 CF 3 ; m = 1, 2, 3; [(nBu 3 P) m CuO 2 CR], [46] R = Me, CF 3 , Ph, CH=CHPh; m = 1, 2, 3). Commonly, copper(II) complexes are solids and need the addition of reducing agents for the deposition of pure copper films at higher temperature (Ͼ250°C).…”