| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS1-ThM |
| Session: | Plasma Processing for Disruptive Technologies (NVM, TSV, etc.) |
| Presenter: | K. Kinoshita, Tohoku University, Japan |
| Correspondent: | Click to Email |
Demands for zero-standby-power systems have increased in order to realize low-carbon society. For this purpose, non-volatile spintronics devices which use magnetic tunnel junction (MTJ) are receiving much attention due to its endurance and high speed. Another important advantage of the spintronics devices is their compatibility to CMOS process. Up to now, 16 Mb MRAM has been in the market. And, developments are ongoing on 300 mm wafer of 90 nm CMOS node or beyond targeting Gb class memory capacity. To combine with the BEOL process, low temperature (<350 degree C) processes are required for additional processes to fabricate the MTJ cell. Use of plasma which enables low temperature process matches the needs.
Whether the target is memory or logic, following three plasma processes are the key to realize the spintronics devices: (a) Damage-less PVD of thin-film multilayered-stack materials. (b) Dry etch for magnetic multilayer stack materials. (c) Protective film CVD over MTJ cell. Multi-target magnetron-PVD is the key equipment to deposit uniform, ultra-thin, multi-stacked MTJ. MgO barrier film quality determined the performances of the MTJ [1]. An Ar milling process has long been used to etch magnetic materials. C-O(X)-based chemistry is increasing attracting attention recently due to its high etch selectivity between hard mask Ta and magnetic materials [2]. Here, degradation of device performances by chemical modification of magnetic materials is one of the issues. Recovery treatment becomes important for the next step [3, 4]. Process chemistry of the protective film CVD should not degrade materials used in MTJ. In addition, high enough quality is needed to protect the MTJ cell during the following BEOL processes [5].
All the unit processes should be evaluated by the MTJ performances after fabricating MTJ in a BEOL structure. In addition, total coordination of BEOL process including these MTJ fabrication processes is required.
This work was supported by JSPS through its FIRST Program.
[1] K. Ono et al., Jpn. J. Appl. Phys. 50, 023001 (2011). [2] I. Nakatani, IEEE Trans. Magn. 32, 4448 (1996). [3] K. Kinoshita et al., Jpn. J. Appl. Phys. 49, 08JB02 (2010). [4] K. Kinoshita et al., to be published on Jpn. J. Appl. Phys. 51, (2012). [5] K. Suemitsu et al., Jpn. J. Appl. Phys. 47, 2714 (2008).