Fabrication of sub-20 nm width ferromagnetic nanocontact structures by shadow evaporation.

The movement of the magnetic domain wall could result in the changing of the contact resistance. Such a resistance change is named as the domain wall Magnetoresistance (DWMR), which can be used as a basic signal of nanodevices. For application, a large DWMR is necessary to improve the device performance. An approach to improve the DWMR value is to fabricate magnetic structures with narrow contact width. However, due to the proximity effect during the process of electron beam lithography (EBL), it is not easy to fabricate sub-20 nm width structures by EBL technique directly. In this paper, we investigated the fabrication of sub-20 nm width nanocontact structures by combined techniques of EBL and shadow evaporation. Upon optimizing the resist thickness, opening width, and the evaporation angle, the contact width was tuned and the corresponding variation trends with these parameters were explored. Using the optimized fabrication conditions, 14 nm wide ferromagnetic contact structures were successfully fabricated.