Room-temperature remote-plasma sputtering of c-axis oriented zinc oxide thin films

Highly c-axis oriented ZnO films have been deposited at room temperature with high rates (similar to 50 nm.min(-1)) using an innovative remote plasma sputtering configuration, which allows independent control of the plasma density and the sputtering ion energy. The ZnO films deposited possess excellent crystallographic orientation, high resistivity (> 10(9) Omega.m), and exhibit very low surface roughness. The ability to increase the sputtering ion energy without causing unwanted Ar+ bombardment onto the substrate has been shown to be crucial for the growth of films with excellent c-axis orientation without the need of substrate heating. In addition, the elimination of the Ar+ bombardment has facilitated the growth of films with very low defect density and hence very low intrinsic stress (< 100 MPa for 3 mu m-thick films). This is over an order of magnitude lower than films grown with a standard magnetron sputtering system. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4736541]