Stress in Y2O3 thin films deposited by radio-frequency magnetron and ion beam sputtering

Thin films of yttrium oxide have been deposited onto substrates of zinc sulfide by rf magnetron and ion beam sputtering. The measured magnitude and the sign of the stresses in these films (interferometric Newton rings method) vary between 7 and 21 x 109 dyn/cm2 and are found to be compressive. The relationship of the measured stress to various deposition parameters is explored. It is proposed that these compressive film stresses increase the flexural strength and apparent indentation fracture toughness of the ZnS substrates