[20p-438-1~21] 8.2 Plasma deposition of thin film, plasma etching and surface treatment

[20p-438-2] 【Highlighted Presentation】Demonstration of Self-limiting Characteristics and Selectivity Control in Annealing Steps for Rapid Thermal-Cyclic ALE

〇Kazunori Shinoda^1,3, Hiroyuki Kobayashi¹, Nobuya Miyoshi², Kohei Kawamura², Masaru Izawa², Kenji Ishikawa³, Masaru Hori³ (1.Hitachi R&D, 2.Hitachi High-Tech, 3.Nagoya Univ.)

Keywords:etching, tungsten, titanium nitride

Self-limiting characteristics of infrared annealing steps in rapid thermal-cyclic atomic-layer etching (ALE) are demonstrated. Films of W and TiN were first exposed to hydrofluorocarbon-based plasma to produce surface-modified layers. The wafers were then annealed by infrared irradiation to remove the modified layers. The cycle of plasma exposure and infrared annealing was repeated ten times. The etched amount per cycle for W increased with the annealing time and saturated when the annealing time exceeded 10 sec. The etched amount per cycle for TiN increased when the annealing time exceeded 10 sec and saturated when the annealing time exceeded 20 sec. These results imply that the ALE process for W and TiN are self-limiting in nature. Moreover, by choosing an optimal infrared annealing time, both highly selective and nonselective ALE for different materials was obtained. For instance, infinitely selective ALE of W over TiN was achieved when infrared annealing time was 8 sec.