[13a-B9-1~11] 8.4 Plasma etching

[13a-B9-11] Atomic Layer Etching of TiN Using Formation and Desorption of Modified Layer

〇Kazunori Shinoda¹, Nobuya Miyoshi¹, Hiroyuki Kobayashi¹, Masaru Kurihara¹, Satoshi Sakai², Masaru Izawa², Kenji Ishikawa³, Masaru Hori³ (1.Hitachi, 2.Hitachi High-Tech, 3.Nagoya Univ.)

Keywords:etching, titanium nitride, atomic layer

Isotropic atomic layer etching of TiN using formation and desorption of an ammonium salt-based modified layer is developed. A nitrogen 1s peak (402 eV), which has been assigned as ammonium salt, was observed after CF-based radical exposure by using x-ray photoelectron spectroscopy. After the samples were annealed, the nitrogen 1s peak at 402 eV disappeared. This phenomenon implies that the film of ammonium salt decomposed and desorbed from the TiN surfaces at elevated temperatures. The preliminary tests of cyclic etching are carried out by repeating radical exposure and thermal annealing. For one cycle of etching, the etching depth increases with increasing radical exposure time and saturates at 0.7 nm. For multiple cycle etching, the etching depth increases with an increasing number of repetitions of the cycle. Tuning of the etched amount per cycle in the range from 0.3 to 0.7 nm was demonstrated by changing the composition of gas mixtures. From these results, it is concluded that the atomic layer etching of TiN was successfully demonstrated.