Microstructure in electrodeposited copper layers; the role of the substrate

摘要

The microstructures of Cu layers, ranging in thickness from 3 to 12 μm, were investigated. The layers were electrodeposited from an acidic copper electrolyte onto two distinct substrate materials important for the micro-components industry: an Au layer with a pronounced -texture, and a nano-crystalline Ni-P layer. The evolutions of surface topography, morphology and crystallographic texture in the layers were investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction analysis, respectively. Distinct surface topographies were observed for Cu layers deposited on the Au and Ni-P substrates. Deposition onto the Au substrate resulted in a very smooth surface of all Cu layers, whereas the Ni-P substrate caused an irregular surface for 3-μm-thick layers of Cu. The crystallographic texture in the Cu layers in the first few micrometres depended strongly on the crystallographic texture in the substrate. The Cu crystallites inherited the < 111 >-orientation of the Au substrate, whilst no preferred crystallographic orientation was observed in the Cu crystallites on the nano-crystalline Ni-P substrate. For Cu layers thicker than 3 μm a <110>-fibre texture developed on both the substrates.