Etching effect on the texture and the stress of copper layers evaporated on Si(100)

Copper thin films were deposited by thermal evaporation on (100) silicon substrates, either unetched or etched with hydrofluoric acid solutions of different concentrations. The effect of the chemical cleaning procedure on the texture and on the stress of the copper films was investigated by X-ray diffraction in the θ–2θ and rocking curve modes. The texture of the deposited copper layers on Si(100) depends greatly on the substrate surface condition. The copper crystallites grow preferentially along the (111) face when the silicon substrate is covered with native silicon oxide, whereas they are preferentially oriented in the (100) direction when the silicon substrate is etched with hydrofluoric acid in order to remove the oxide. In this latter case, the interfacial energy imposes the epitaxial growth mode of the copper layer, while in the former case, the lowest surface energy of the (111) copper face, determines the growth mode. The stress appearing in the copper layer is due to the epitaxial growth of the crystallites.