Spatial profile of Al-ZnO thin film on polycarbonate deposited by ring-shaped magnetized rf plasma sputtering with two facing cylindrical Al₂O₃ – ZnO targets

Abstract

Radial profiles of the ion saturation current are measured in a ring-shaped magnetized radio-frequency plasma sputtering process with two facing cylindrical ZnO targets including Al2O3 (2% wt.). The profile has a non-uniform shape with a peak whose position corresponds to the target near the electrode due to the effect of the magnetic field distribution. It becomes uniform at large distances between the substrate and a target (d st ≥ 50 mm). The radial profile of the resistivity of the Al-ZnO (AZO) films deposited on a polycarbonate plate at Ar gas pressure of 0.27 Pa is uniform at about 10-3 Ω·cm for d st ≥ 50 mm. The films deposited at various positions and room-substrate-temperature also show a good crystallinity based on an X-ray diffraction peak of about 33.95 - 34.44°. The grains exhibit a preferential orientation along the [002] axis with its size ranging from 18.15 to 28.17 nm. A higher transmittance of 95.6 % in the visible region is also obtained.

Spatial structures of rf ring-shaped magnetized sputtering plasmas with two facing cylindrical ZnO/Al2O3 targets

“…Therefore, in order to avoid the plasma damage to the AZO films, the facing target sputtering method [25][26][27][28][29][30][31][32][33][34] is widely utilized. In general, two plate targets are faced with a separation and the permanent magnets are positioned in their backsides to magnetize the plasma.…”

“…In our previous works, 29,30) a novel facing target sputtering method has been developed to improve the lower deposition rate: Two cylindrical targets are mounted in a ring-shaped hollow groove of an aluminum disk driven by an rf voltage of 13.56 MHz. Thus, our facing target system has an only one opening area.…”

“…70.2 mm and 95.6 mm, respectively, and outer diameters of 76.2 mm and 101.6 mm, respectively, are mounted in the groove of the ring-shaped hollow electrode. 30) A magnetic field to confine the plasma in the groove region is generated by placing permanent magnets behind both sidewalls of the groove as shown in Fig. 1 and described in more detail in Sect.…”