Dry Etching of Nanosized Ge{sub}1Sb{sub}2Te{sub}4 Patterns Using TiN Hard Mask for High Density Phase-Change Memory

摘要

Being able to pattern and etch chalcogenide materials in nanometer scale is essential for the integration of high density chalcogenide random access memory. We investigated dry etching methods for the patterning of Ge{sub}1Sb{sub}2Te{sub}4 films in CHF{sub}3/O{sub}2 gas mixture using reactive-ion etching system. The gas species CHF{sub}3/O{sub}2 can reach good etched features with smooth sidewall and a taper angle of 86°. The nanosized Ge{sub}1Sb{sub}2Te{sub}4 patterns were defined by electron-beam lithography using hydrogen silsesquioxane as negative type e-beam resist. A hard mask of TiN, to which the selectivity of Ge{sub}1Sb{sub}2Te{sub}4 is as high as 12, was chosen for employing a CHF{sub}3/O{sub}2 gas mixture for Ge{sub}1Sb{sub}2Te{sub}4 etching. The Ge{sub}1Sb{sub}2Te{sub}4 line with width of 170 nm could be successfully obtained with good profiles and uniformity using these optimized patterning conditions, which could be very helpful for fabricating high density chalcogenide random access memory based on Ge{sub}1Sb{sub}2Te{sub}4.