Novel method for fabricating deep submicron Nb/AlOx/Nb tunnel junctions based on spin-on glass planarization

A novel method for the fabrication of sub-1-mu m Nb/AlOx/Nb tunnel junction s has been developed, that is based on spin-on glass planarization. The Nb/ AlOx/Nb sandwich and the Nb wiring layer are structured by reactive ion etc hing using e-beam lithography. The insulation between the base electrode an d the wiring layer is realized by planarized spin-on glass. Single electron transistors with junction areas of 0.3 mu m x 0.3 mu m and linear arrays o f junctions with sizes down to 0.5 mu m x 0.5 mu m have been fabricated and measured.