Microstructure in electro deposited copper layers; the role of the substrate

The microstructures of Cu layers, ranging in thickness from 3 to 12 mum, we re investigated, The layers were electrodeposited from an acidic copper ele ctrolyte onto two distinct substrate materials important for the micro-comp onents industry: an Au layer with a pronounced < 1 1 1 > -texture, and a na no-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-ra y diffraction analysis, respectively. Distinct surface topographies were ob served for Cu layers deposited on the Au and Ni-P substrates. Deposition on to the An substrate resulted in a very smooth surface of all Cu layers, whe reas the Ni-P substrate caused an irregular surface for 3-mum-thick layers of Cu. The crystallographic texture in the Cu layers in the first few micro metres depended strongly on the crystallographic texture in the substrate. The Cu crystallites inherited the < 1 1 1 > -orientation of the Au substrat e, whilst no preferred crystallographic orientation was observed in the Cu crystallites on the nano-crystalline Ni-P substrate. For Cu layers thicker than 3 pm a <1 1 0 > -fibre texture developed on both the substrates. (C) 2 001 Elsevier Science Ltd. All rights reserved.