Properties of W--N and Mo--N films prepared by reactive sputtering

The structure and properties of W--N films up to 22 μm thick prepared by a reactive dc magnetron sputtering process are reported. It has been found that the properties of the deposited films not only depend on the nitrogen partial pressure in the argon--nitrogen gas mixtures but also on total gas pressure and input power during sputtering. The rate of deposition decreased with increase of nitrogen partial pressure, but was higher at higher total pressure and input power. The resistivity increased with nitrogen partial pressure but was lower at lower total gas pressure and higher input power. The hardness of W--N films could be varied from 600 to 3000 kg/mm2 depending on sputtering conditions. The hardness, in general, increased with nitrogen partial pressure with higher value at higher total pressure and input power. X-ray diffraction did not indicate presence of nitride phases when the content of nitrogen in the argon--nitrogen gas mixtures during sputtering was below 10%, and the total gas pressure was <40 mTorr. W2N was observed when the nitrogen content was over 30% and also when the nitrogen content was over 10% and total gas pressure was over 40 mTorr. These results are consistent with composition determined by the microprobe measurements. Similar studies on Mo--N films made by dc and rf magnetron reactive sputtering methods are reported. Hardness values for the Mo--N films of more than 2200 kg/mm2 have been observed