Deposition of polycrystalline thin films with controlled grain size

Difficulties in controlling the grain size and size distribution in polycrystalline thin films are a major obstacle in achieving efficient performance of thin film devices. In this paper we describe a sputtering technology that allows the control of the grain size and size distribution in sputtered films without the use of seed layers, substrate heating or additives. This is demonstrated for three different materials (Cr, NiFe and FeMn) via transmission electron microscopy imaging and grain size analysis performed using the cumulative percentage method. The mean grain size was controlled only via the sputtering rate. We show that higher sputtering rates promote the growth of larger grains. Similar trends were obtained in the standard deviation, which showed a clear reduction with the sputtering rate.