Abstract
Nanocrystalline Zr(N,O) thin films, consisting of ZrN and monoclinic ZrO2 were successfully deposited on p-type Si (100) substrates using hollow cathode discharge ion-plating (HCD-IP) system. With the increase of oxygen flow rate ranging from 0 to 10 sccm, the primary phase for as-deposited films evolved from pure ZrN phase to nearly amorphous structure and further to a single m-ZrO2 phase. After annealing, heat treatment induced phase transformation in the samples deposited at 8 and 10 sccm oxygen flow rates, which revealed that stoichiometric crystalline Zr2ON2 was derived from the m-ZrO2 structure containing N defects. Phase separation and phase transformation of Zr(N,O) thin films before and after annealing was discussed, and a hypothesis was proposed to explain the phenomenon. The effect of heat treatment on the composition, microstructure and properties of the as-deposited Zr(N,O) films was also investigated. Phase transformation induced by heat treatment might significantly relieve the residual stress, and the residual stress of whole thin films was almost equal to that of each constituent phase for all samples after 900 ℃ annealing. In addition, the packing density of thin films mostly increased significantly after heat treatment, especially for the samples at 8 and 10 sccm oxygen flow rates, which undergone phase transformation induced by annealing. The coloration for as-deposited films varied from light gold to slate gray as the oxygen content increased, and it remained mostly the same before and after heat treatment.