Formation and control of microstructure defects of tungsten prepared by chemical vapor deposition method

Tungsten coatings were deposited on pure copper substrates using WF₆ as the precursor by chemical vapor deposition (CVD) method. The formation of the microstructure defects of the tungsten deposits was analyzed by OM and SEM. The results show that the reactant concentration fluctuation has a significant impact on the microstructure of tungsten prepared by CVD method. When n (WF₆): n (H₂) ≥ 1:3, the microstructure of tungsten is columnar grain; when n (WF₆): n (H₂) < 1:3, the grains of the deposited layer are refined and the microstructure presents a fine grains multilayer structure. Moreover, the shapes of the impurities can also influence significantly on microstructure of the layer. When there is one-dimensional impurity on the surface of substrate, the surface of deposition has obvious bulge, which seriously affects the deposits surface quality and microstructure uniformity; when there is zero dimensional impurity during the deposition process, the deposit appears radial structure.