[19p-C204-1~17] 8.2 Plasma deposition of thin film, plasma etching and surface treatment

[19p-C204-4] Rapid Thermal Cyclic Atomic-Level Etching of Tungsten

〇Kazunori Shinoda¹, Yuko Hanaoka², Nobuya Miyoshi¹, Hiroyuki Kobayashi¹, Kohei Kawamura², Masaru Izawa², Kenji Ishikawa³, Masaru Hori³ (1.Hitachi R&D, 2.Hitachi High-Tech, 3.Nagoya Univ.)

Keywords:plasma, etching, tungsten

Isotropic atomic level etching of tungsten using formation and desorption of a tungsten fluoride-based modified layer is developed. Samples were exposed to radicals that were generated in fluorocarbon-based plasmas at −22°C. Tungsten 4f peaks and a fluorine 1s peak, which were assigned to tungsten fluoride, were observed by x-ray photoelectron spectroscopy. After the samples were annealed, the peaks that originated from tungsten fluoride disappeared. Cyclic etching tests were carried out by repeating plasma exposure and infrared irradiation. The amount of etched tungsten increased as the number of cycles increased. In comparison, etching of SiO₂ and TiN was not detected. Conformal etching profiles of patterned samples were obtained. From these results, it is concluded that selective, atomic level etching of tungsten was successfully demonstrated.