Closely spaced nanomagnets by dual e-beam exposure for low-energy nanomagnet logic

The effect of nanomagnet spacing on required clock field has been studied by micromagnetic simulation for supermalloy (Ni79Fe16Mo5) dots with dimensions 90 × 60 × 20 nm3 and 120 × 60 × 20 nm3. Reduction of the inter-magnet spacing for both dimensions has resulted in reduction of the required clock field in the simulation. A dual e-beam exposure technique has been developed to allow fabrication of ultra dense features using conventional poly(methylmethacrylate) e-beam resist. Nanomagnet logic (NML) datalines of supermalloy dots with ∼10 nm and ∼15 nm spacing have been fabricated using dual e-beam exposure with a 3σ overlay accuracy of ∼4 nm. Fabricated NML datalines have been characterized using magnetic force microscopy for various clock fields. Datalines of both spacing have shown proper NML functionality with a clock field as low as 60 mT.