title: Fabrication of nano-sized magnetic tunnel junctions using lift-off process assisted by atomic force probe tip.
abstract: We present a fabrication method for nano-scale magnetic tunnel junctions (MTJs), employing e-beam lithography and lift-off process assisted by the probe tip of atomic force microscope (AFM). It is challenging to fabricate nano-sized MTJs on small substrates because it is difficult to use chemical mechanical planarization (CMP) process. The AFM-assisted lift-off process enables us to fabricate nano-sized MTJs on small substrates (12.5 mm x 12.5 mm) without CMP process. The e-beam patterning has been done using bi-layer resist, the poly methyl methacrylate (PMMA)/ hydrogen silsesquioxane (HSQ). The PMMA/HSQ resist patterns are used for both the etch mask for ion milling and the self-aligned mask for top contact formation after passivation. The self-aligned mask buried inside a passivation oxide layer, is readily lifted-off by the force exerted by the probe tip. The nano-MTJs (160 nm x 90 nm) fabricated by this method show clear current-induced magnetization switching with a reasonable TMR and critical switching current density.
authors.affiliation: Center for Spintronics Research, Korea Institute of Science and Technology, Seoul 136-791, Korea.
authors.forename: Ku Youl
authors.initials: KY
authors.lastname: Jung
authors.forename: Byoung-Chul
authors.initials: BC
authors.lastname: Min
authors.forename: Chiyui
authors.initials: C
authors.lastname: Ahn
authors.forename: Gyung-Min
authors.initials: GM
authors.lastname: Choi
authors.forename: Il-Jae
authors.initials: IJ
authors.lastname: Shin
authors.forename: Seung-Young
authors.initials: SY
authors.lastname: Park
authors.forename: Kungwon
authors.initials: K
authors.lastname: Rhie
authors.forename: Kyung-Ho
authors.initials: KH
authors.lastname: Shin