Fabrication of a nanosized current-driven spin valve device using proximity correction in electron-beam lithography

Abstract

Nanosized junctions of 100×200nm2 size were successfully fabricated on magnetic metallic multilayers in a current-driven spin-valve device by the suitable choice of the electron-beam resist, as well as careful control of back-scattering effects in electron-beam lithography. ZEP520A was chosen as an e-beam sensitive resist because its dry-etching resistance is high enough to act as an etching mask during the ion milling. The severe back-scattering effect from the underlying metallic multilayers was reasonably modified by employing the doughnut-pattern method. The doughnut-pattern method gave a set of proximity parameters (α,β, and η) with which we did the simulation to obtain the effective dose factors of each segment of the pattern. The magnetotransport signals from our devices were quite comparable to previous results from those made by different methods of other research groups. Consequently, the fabrication of nanosized current driven spin valves can be performed less complicatedly by using ZEP520A as an etching mask.