4 Linear Relationship between Reactive Gas Flow Rate 6and Target Power at Mode Transitions in Reactive 89 Sputtering

Mode transitions in reactive sputtering of metal (Ti, V) oxides are studied. Under a controlled Ar gas pressure at a flow rate of 10 sccm, direct current sputtering plasma was generated. The oxygen flow rate Q and discharge power P were changed in two ways (Q was varied at fixed P, and vice versa), and the mode transitions were monitored using the state jump in the discharge voltage. When the transition points (P, Q) were plotted as two-dimensional (2D) maps, the metal -to -oxide and oxide -to -metal transition points were found to be located on two corresponding straight lines that passed through the origin, irrespective of how the parameters were varied. The origin of this behavior is discussed and ascribed to the linear relationship between the input power and the sputter etching rate of the target. These results also suggest that the metal -mode, hysteresis, and oxide -mode regions of the 2D map can be determined by a few pilot experiments. By depositing vanadium oxide films under conditions in the oxide -mode region, near its boundary, films with very similar optical properties could be obtained.