Research Of Preparation And Residual Stress Of Thin Films Based On The TFDC Theory

Since the 21st century, because of mutual combination and propulsion of the film materials, electrode position technology and surface physics technology, it had not only been promoted a rapid development of the film science and technology, but also promoted the development and application of the film materials. Heterogeneous metal films electrodeposited on conductive substrates are often at a strain state, and the residual stresses have a great influence on the stability, usability and reliability of the film devices, the generated mechanism and quantitative calculation of the residual stresses are always emphasizes of research.In this paper, different electrodeposited processes of the single-layer Cu, Ni and Cr films with different thickness on different substrate were investigated, and then the electrodeposited processes of Cu, Ni and Cr films were optimized. The warping distance of the single-layer Cu, Ni and Cr films on different substrates were measured by using the on-line measurement system, then the average residual stress and the distributing residual stress were calculated, the generated mechanism of the residual stress was analyzed base on Thomas - Fermi - Dirac - Cheng (TFDC) electronic theory. Therefore TFDC electronic theory was verified. The Cu/Ni multilayer films with various modulation wavelengths were prepared by double bath technology, their cross-sectional microstructure were observed and their hardness were tested.The results show, under the room temperature, the electrodeposited Cu films are bright and neat which are much appropriate under current density of 0.8 1 A·dm^-2; when the current density is 0.6 1.2 A·dm^-2, the electrodeposited Ni films are also bright and neat, but the average electrodeposited rates are different, basically the average electrodeposited rates are related to current density, when the current density for 1 A·dm^-2, the average electrodeposited rate of the Ni films is 2.509 nm·s-1 from the experiment; at 45°C and current density of 15 A·dm^-2, the Cr film has a good quality, and the average electrodeposited rate is 4.01 nm·s-1. The residual stresses of the Ni films on various substrate materials are tension stress, and the Cu films in carbon steels, pure iron are tension stress, but in pure Ni substrate are compressive stress, the Cr films in industrial pure iron substrate are tension stress. When the film thickness is much thinner, the average residual stresses and the distributed stresses of two kinds of films change dramatically with the increasing of the film thickness; the two residual stresses trend to constants with the increasing of the film thickness, it indicates that the interface stress exists in residual stress. Both the film materials and the substrate materials have great influences on the residual stress of films; the residual stresses of the thin Cu, Cr and Ni films on different substrates mainly come from the interface stress, then the results of judgment are consistent with analysis based on TFDC electronic theory. The Cu/Ni multilayer films are electrodeposited and analyzed its structure and hardness by double bath technology, the results of that are important practical significance for preparing thinner nanoscale multilayer films and the study of the mechanical properties and theoretical calculation about them.