Tungsten Film Coating Method Using Tungsten Oxide Powders(一)

Disclosed is a tungsten film coating method using tungstenoxide powders including the steps of contacting the tungstenoxide powders with a metal substrate and carrying out thermal reduction treatment thereon at a temperature of at least 650° C. under a hydrogen atmosphere just to coat the tungsten film on the metal substrate. Accordingly, the present methodenables to provide a simple method of coating a tungsten thin film on a metal substrate using the phenomenon of tungsten migration through vapor phase when thermal reduction treatment is carried out on tungstenoxide powders without using previous chemical or physical vapor depositions requiring expensive precision equipments or causing environmental pollution.

First of all, tungstenoxide (WO3or WO2.9) powders having a grains size of 1˜10 μm are put on a metal substrate such as Cu, Ni, Fe, Co, Cr, W, or the like. When thermal reduction treatment is carried out thereon at 650° C. (temperature from which the metal substrate is coated with tungsten by reduction of the tungstenoxide powders) under a hydrogen atmosphere, the hydrogen gas reacts with oxygen contained in the tungstenoxide powders. Hence, steam is formed as well as composition of tungstenoxide is changed into WO2. Such WO2powders react with adjacent moisture, as shown in the following chemical equation 1, so as to turn into tungstenoxide of WO2(OH)2as a gas phase and hydrogen. The generated gaseous phase tungstenoxide {WO2(OH)2} moves to the neighboring metal substrate by diffusion, and then reacts with adjacent hydrogen again, as shown in the following chemical equation 2, so as to be reduced to solid phase tungsten. In this case, if the metal substrate is around, the reaction by the chemical equation 2 occurs on the metal substrate preferentially (heterogeneous nucleation and growth) so as to coat the metal substrate with a tungsten thin film a few nanometers (nm) to tens of micrometers (μm) thick.

WO2(S)+2H2O(g)WO2(OH)2(g)+H2(g) [Chemical Equation 1]
WO2(OH)2(g)+3H2(g)W(S)+4H2O(g) [Chemical Equation 2

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