Ion beam etching process for high-density spintronic devices and its damage recovery by the oxygen showering post-treatment process

• Published in: Japanese Journal of Applied Physics Vol. 56; no. 4S; pp. 4 - 04CE09
• Main Authors: Jeong, Junho, Endoh, Tetsuo
• Format: Journal Article
• Language: English
• Published: The Japan Society of Applied Physics 01.04.2017
• Subjects: Arrays; Damage; Etching; Ion beams; Magnetoresistivity; Oxygen; Reactive ion etching; Tunnel junctions
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.56.04CE09

The electric short fail trend of the perpendicular magnetic tunnel junctions (p-MTJs) caused by the ion beam etching (IBE) process is studied at various ion beam angles and cell-to-cell space widths. The number of electric short fails increases markedly at an ion beam angle greater than 35° and a cell-to-cell space width less than 30 nm at the assumed MTJ height including a hard mask (HM) of 20 nm. In order to recover these electric short fails, we propose the selective oxidation process called the oxygen showering post-treatment (OSP). By the OSP process, the number of electric short fails in sub-30-nm-spaced MTJ arrays is reduced from 25 to 0.8%, and the magnetoresistance (MR) is increased from 99 to 120%. By this result, we can verify that the damaged layer is recovered successfully by the OSP, and that the OSP can be a universal post-treatment process even beyond the 20 nm design rule for use in both reactive ion etching and IBE schemes.