Chemical Mechanical Planarization of Amorphous Ge_2Sb_2Te_5 using KCIO_4 as oxidizer in Acidic Slurry

摘要

Amorphous Ge_2Sb_2Te_5 (a-GST) chemical mechanical planarization (CMP) using KCIO_4 as the oxidizer in an acidic slurry is investigated in the present work. It is shown that the removal rate (RR ) of the a-GST firstly increases and then tends to saturate when the KCIO_4 concentration is greater than 0.8 wt%, but the static etch rate (SER) linearly increases from low to high KCIO_4 concentration. To understand the oxidation-reaction capability of Ge, Sb and Te, depth profiles of composition of elements and etch morphology of a-GST immersed in the slurry for some time are measured, respectively. It is found that selective corrosion occurs among Ge, Sb and Te, and an accumulation of Te and loss of Ge in a-GST surface region are obvious observed, especially at high KCIO_4 concentrations. Temperature dependent sheet resistance measurements of all the samples pre- and post-CMP reveal a similar trend, which implies a-GST CMP is able to keep its characteristic well.