Low temperature and high rate deposition of ferrite thin films by reactive sputtering method using electron cyclotron resonance

A reactive sputtering apparatus utilizing electron cyclotron resonance (ECR) was developed for the deposition of thick oxide or nitride films usable in electric devices. A high deposition rate of 44 nm/min. was achieved using a conic alloy target and the deposited soft ferrite thin films were successfully crystallized without heat treatment during film deposition. Magnetic and physical properties for the film were analyzed in terms of saturation magnetization, coercivity, uniformity of film thickness, and inner stress. Obtained properties were consistent with soft magnetic films. The result confirms the oxygen partial pressure ratio to deposition rate strongly affected the magnetic properties. Well crystallized, ultra thin 3-nm-thick Ni-Zn ferrite (100) films, were also successfully deposited on MgO (100) underlayers. These results imply the ECR sputtering method is one of the most effective deposition methods for highly crystallized polycrystalline thick and thin films. Crystal orientation was improved by low target voltage sputtering as well as a relatively low deposition rate. Further improvement is considered to be possible by deposition at lower base pressures.