Published online by Cambridge University Press: 21 March 2011
This paper describes the influence of the topography of a lithographically patterned substrate (aluminium electrodes on a CVD diamond film) on the uniformity of sputtered ZnO films. Diamond films with an average surface roughness of ∼1nm, had aluminium electrodes (thickness 80nm, linewidth/space 2.6μm) patterned on them. ZnO was RF sputtered on to the substrate and the uniformity of the ZnO grain structure was examined using SEM, XRD and AFM. Abrupt changes in topography at the edges of the aluminium electrodes resulted in poor alignment of ZnO grains. SEM/AFM micrographs show misalignment of ZnO grains at the edges of the raised electrodes. When the electrodes were recessed into the diamond film, using a damascene-like process, the SEM/AFM micrographs showed improved grain uniformity of ZnO. XRD showed a significant increase in the c-axis (002) orientation and an absence of the (101) orientation. AFM micrographs also showed the improvement in the ZnO surface topography. These results may be of significance to high frequency Surface Acoustic Wave (SAW) devices.