Reactive Ion Etching of Ge_2Sb_2Te_5 in CHF_3/O_2 Plasma for Nonvolatile Phase-Change Memory Device

摘要

The etching characteristics of Ge_2Sb_2Te_5 (GST) films were studied with a CHF_3/O_2 gas mixture using a reactive ion etching system. The variations of etch rates and etch profiles caused by changes in the gas-mixing ratio were investigated under constant pressure and applying power. Then the etching parameters were optimized. The etch rate is up to 83 nm/min, and the selectivity of GST to SiO_2 is as high as 3 times. The smooth surface was achieved using optimized etching parameters of oxygen concentration of 4 percent in the CHF_3/O_2 gas mixture, pressure of 3G mTorr, and power of 150 W.