Modification of the properties of D.C. magnetron sputtered magnetic thin films by self-bias

2018-12-14T15:20:41Z (GMT) by Edward S. Warner
In this thesis a method to control the deposition process of D.C. magnetron sputtered magnetic thin films is described. A biased anode, situated in front of the magnetron, is used to alter the plasma characteristics which influence the film deposition process. The magnetic field configuration which results from biasing the anode leads to self-biasing at the film-substrate location. Control of this film self-bias voltage allows for controlled ion bombardment of the substrate. The technique is investigated using Cobalt as the target material. With the given experimental configuration, self-bias voltages up to -40 V at the substrate location could be achieved. It is demonstrated that the use of self-bias and ensuing ion bombardment, during film growth at the substrate, influence the micro-structure and properties of the deposited films. The micro-crystalline structure and coercivity of magnetron sputtered Cobalt films exhibited considerable variation with film self-bias. For increasing self-bias, the film coercivity attained a maximum value then decreased toward a value less than that of the unbiased case. It is found that the maximum value of coercivity coincides with the maximum film particle diameter. The films are found to consist essentially of single-domain particles, which are responsible for the observed magnetic properties of the films.