TaN underlayers for spin valves deposited directly on top of Si substrates

Abstract

TaN underlayers for spin valves were studied, which were deposited directly on top of Si substrates. The experimental results obtained with the TaN underlayer were compared with those obtained with other (Ta, Mo, and MoN) underlayers. The spin valve structure was Si/Underlayer (t angstrom)/NiFe (21 angstrom)/CoFe (28 angstrom)/Cu(22 angstrom)/CoFe(18 angstrom)/IrMn (65 angstrom)/Ta(25 angstrom). The TaN underlayer for a spin valve element exhibited good adhesion to the Si substrate. The XRD patterns of the annealed TaN on bare Si substrate at 900 degrees C showed no Ta silicide phases, which suggests that the TaN layer may also be used as a diffusion barrier between Si substrate and the ensuing spin valve active layers, as well as an underlayer. A spin valve element having TaN underlayer deposited directly on top of a Si substrate showed a high MR ratio of about 8.3% after annealing at 200 degrees C. It is concluded that it is advantageous to use a TaN underlayer if one wants to fabricate spin valve elements directly on top of Si substrates. (C) 2008 Elsevier B.V. All rights reserved.