The study of Co-W-P thin film as diffusion barrier layer by electroless plating process

• Main Authors: Sin-Sian Wu, 吳信賢
• Other Authors: Ting-kan Tsai
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/khkv84

碩士 === 國立虎尾科技大學 === 光電與材料科技研究所 === 95 === In this work, The Co-W-P films with 100nm thickness as diffusion barrier were deposited on Si substrate in an electroless plating bath at pH value of 8.5, 9.0 and 9.2, respectively. Before electroless plating, the Si substrate was successively eleansed, sensitized and activated. After a Cu film with 150nm thickness was deposited on Co-W-P film by electroless plating, the sample was annealed in vaccum for 5 minutes in a rapid thermal annealing (RTA) furnace at 300~800℃. The annealed samples were characterized using an X-ray diffraction (XRD) for phase structure, a scanning electron microscope (SEM) and field emission scanning electron microscope (FE-SEM) for morphology, a transmission electron microscope (TEM) for microstructure, and a four point probe for property of diffusion barrier. The result showed that the Co-W-P films (100nm) grown at pH value of 9.0 and 9.2 were good diffusion barriers which could hinder against the diffusion of Cu up to 600℃, and the Co-W-P film (100nm) grown at pH value of 8.5 could hinder against the diffusion of Cu only below 500℃. However the Co-W-P film grown at pH value of 9.0 could hinder against the diffusion of Cu only below 500℃, when its thickness was 30nm. The mechanism for the failue of Co-W-P diffusion barrier can be deduced as follows. When temperature was increased up, the Cu atom in Cu/CoWP/Si structure would diffuse into Si substrate through Co-W-P film and became copper silicide with Si, the Co atom in Cu/CoWP/Si structure would diffuse through Cu film and form particle on the surface of Cu film, finally the Co atom would react with the Si atom of capper silicide and become cobalt silicide. The electroless Co-W-P film on Si substrate has pillar structure. The growth rate of the electroless Co-W-P film deposited at pH value of 9.0 and temperature of 85℃ can be increased to 20.28 nm/min from 13.65 nm/min only by adjustment of the concentration conplexing agent (sodium citrate). The activation energy for the deposition of this Co-W-P film is 45.02 KJ/mole.