Nickel films of about 20 nm thickness and a mean domain size of 7 nm were treated in a microwave plasma (SLAN, 2.45 GHz). The nickel films were exposed to argon –hydrogen plasma using different negative substrate voltages to study the hydride formation.
The nickel hydride films were investigated by grazing incidence X-ray diffractometry (GIXD) to control the phase formation. Thickness and density were determined by X-ray reflectometry (XR); sample topology was studied by atomic force microscopy.
The effect of hydrogen plasma depends on the used negative substrate voltage. Without substrate voltage no chemical reaction occurs. Solely a partial sputtering and a recrystallization of the small Ni domains can be observed.  
At negative substrate voltages (-25 V, -50 V, -75 V) a hexagonal Ni₂H phase is formed in a first quick reaction step. In a subsequent plasma chemical reaction this Ni₂H is transformed into cubic NiH. The reaction rate of the NiH formation increases with increasing negative substrate voltage.
The kinetic processes will be discussed using a modified isoconversional kinetic analysis.

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