Substrate planarization studies on IBAD substrates

Abstract : To achieve high critical currents in 2nd generation superconductors deposited on metallic substrates, substrate average roughness and texture of the buffer layer are key factors. This study is about planarization of IBAD substrates using an inductively coupled RF discharge operating at 13.56MHz. A pancake coil antenna was used to construct the inductively coupled discharge system. Exposure to an Ar plasma for varying Ar pressures and time 15 min to 1 hr created linearized substrates. Surface roughness was measured using AFM as well as surface profilometer. Unpolished lnconel substrates have been studied under varying RF plasma conditions, such as pressure, RF power, and etch time to determine effects on substrate roughness. AFM and KLA-TENCOR SP measured average surface roughness (Ra) of the planarized samples. The best Ra found on plasma etched substrate is 4nm under 240 mTorr pressure and 100 W RF power and 30 min time from AFM analysis. The Ra values for lnconel substrates vary between 35-51 nm under varying conditions. Our initial results suggest that there is a decreasing tendency in Ra with the increase of Ar pressure.