Air Products and SNU present low temperature ALD process for GST for PCRAM

Phase change random access memory (PCRAM) is one of the promising next-generation memory technologies because of its nonvolatile data retention property and rapid writing and reading speeds. Air Product and Seoul National University (SNU) now presents a stable and reliable  conformal ALDprocess for depositing the challenging GST material at low temperature. The Gb–Sb–Te films were deposited using a 200 mm shower head type ALD reactor from Quros (CN-1, Plus-200).

Combined Ligand Exchange and Substitution Reactions in Atomic Layer Deposition of Conformal Ge2Sb2Te5 Film for Phase Change Memory Application

Taeyong Eom, Taehong Gwon, Sijung Yoo, Byung Joon Choi, Moo-Sung Kim, Iain Buchanan, Sergei Ivanov, Manchao Xiao, and Cheol Seong Hwang

 

For phase change memories application, Ge–Sb–Te films were prepared by a stable and reliable atomic layer deposition (ALD) method. Ge(OC2H5)4, Sb(OC2H5)3, [(CH3)3Si]3Sb, and [(CH3)3Si]2Te were used to deposit various layers with compositions that can be described by combinations of GeTe2–Sb2Te layers including Ge2Sb2Te5 at a substrate temperature as low as 70 °C. A shift in composition of Sb–Te films from Sb2Te3 to Sb2Te composition was achieved by combining ligand exchange and substitution reaction between Sb in [(CH3)3Si]3Sb and Te in the Sb2Te3 layer. This surface-limited ALD process allowed highly conformal, smooth, and reproducible film growth over a contact hole structure, highlighting the feasibility of phase change memory applications.