Dry etching of nanosized Si_2Sb_2Te_5 patterns using UN hard mask for high density phase-change memory

摘要

Compared to DRam and flash memory, CRAM (chalcogenide random access memory), which is a non-volatile memory using a reversible phase change between amorphous and crystalline state, has many advantages such as high speed, high sensing margin, low operating voltage, and is being pursed as a next generation memory. Being able to pattern and etch chalcogenide in nanoscale is essential for the integration of CRAM. We investigated the etching characteristics of Si_2Sb_2Te_5 in a CHF3/O2 gas mixture using a reactive ion etching system. The nanosized Si_2Sb_2Te_5 patterns were defined by electron-beam lithography, and a hard mask TiN was chosen for Si_2Sb_2Te_5 etching. Using these optimized etching parameters and patterning conditions, 500nm Si_2Sb_2Te_5 square could be successfully obtained with good profiles and uniformity.