Etching characteristics of Ge2Sb2Te5 using high-density helicon plasma for the nonvolatile phase-change memory applications

We investigated the etching behaviors of GST, which has been mainly employed for the realization of phase-change type nonvolatile memory devices, using high-density helicon plasma etching system under the various etching gas conditions. Our results provide the etch rates of GST thin films as a function of gas mixing ratio when the gas mixtures of Ar/Cl-2 and Ar/CHF3 were applied. It was found that the etch selectivities of GST to SiO2 and to TiN were optimized at Ar/Cl-2 = 90/10 and Ar/CHF3 = 80/20, respectively. It was also confirmed that there is no significant change in composition of GST after the etching process. Using the obtained results, we can design the etching process in a systematic way for the fabrication of GST-loaded phase-change type memory devices.