Fabrication of Sub-100 nm Wires and Dots in GaAs/AlGaAs Multiquantum Well Using Focused Ion Beam Lithography

We describe a new lateral patterning technique using focused ion beam (FIB) lithography and also two subsequent pattern transfer processes consisting of reactive ion etching and reactive ion beam etching. In the FIB lithography we used a trilevel resist structure consisting of a CMS resist, an Al film, and an SiO2 film. This technique provided 60-nm-wide wires and 100 nm dots in a GaAs/AlGaAs multiquantum well (MQW). Twenty-five-nm-wide wires are also fabricated in GaAs by narrowing the SiO2 mask laterally by wet etching.