Thermal atomic layer etching (ALE) is a promising method for isotropic etching with atomic level precision and high conformality over three-dimensional structures. In this study, a thermal ALE process for titanium nitride (TiN) films was developed using surface modification with a Cl2/Ar downstream plasma followed by infrared (IR) annealing of the films. The oxygen-free Cl2-based plasma was adopted to enable highly selective etching of TiN with regard to various materials. It was confirmed that spontaneous etching of TiN during radical exposure can be suppressed at a surface temperature of −10 °C. Measurements of etch per cycle (EPC) of TiN demonstrated that the EPC is self-limiting with respect to both the radical exposure and IR annealing times. With repeated steps of self-limiting radical exposure and IR annealing, TiN was etched at 2.0 nm/cycle, while no thickness change was observed for poly-Si, SiO2, Si3N4, W, and HfO2. The selectivity to amorphous carbon was higher than 4. X-ray photoelectron spectroscopy analysis revealed that during surface modification, NClx species sublimate spontaneously, while TiClx species remain in the surface-modified layer on TiN. This TiClx-based modified layer desorbs in the IR annealing step, and the TiN surface then returns to its original condition (pristine TiN) before surface modification.
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Atomic layer etching of titanium nitride with surface modification by Cl radicals and rapid thermal annealing
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Research Article|
April 05 2022
Atomic layer etching of titanium nitride with surface modification by Cl radicals and rapid thermal annealing
Special Collection:
Atomic Layer Etching (ALE)
Nobuya Miyoshi
;
Nobuya Miyoshi
a)
Hitachi High-Tech America, Inc.
, 6357 NE Evergreen Parkway, Building D, Hillsboro, Oregon 97124
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Nicholas McDowell;
Nicholas McDowell
Hitachi High-Tech America, Inc.
, 6357 NE Evergreen Parkway, Building D, Hillsboro, Oregon 97124
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Hiroyuki Kobayashi
Hiroyuki Kobayashi
Hitachi High-Tech America, Inc.
, 6357 NE Evergreen Parkway, Building D, Hillsboro, Oregon 97124
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a)
Electronic mail: nobuya.miyoshi.wp@hitachi-hightech.com
Note: This paper is part of the 2023 Special Topic Collection on Atomic Layer Etching (ALE).
J. Vac. Sci. Technol. A 40, 032601 (2022)
Article history
Received:
February 24 2022
Accepted:
March 22 2022
Citation
Nobuya Miyoshi, Nicholas McDowell, Hiroyuki Kobayashi; Atomic layer etching of titanium nitride with surface modification by Cl radicals and rapid thermal annealing. J. Vac. Sci. Technol. A 1 May 2022; 40 (3): 032601. https://doi.org/10.1116/6.0001827
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