Fabrication of silicon dioxide nanocapillary arrays for guiding highly chargedions

Abstract

This paper demonstrates the fabrication of a membrane permeated by a silicon dioxidenanocapillary array for manipulating highly charged ions at the nanoscale. The fabricationmethod involves (i) the formation of pores at the nanoscale on lithographicallypatterned, n-type silicon using photo-assisted electrochemical etching, followed by(ii) thermal oxidation, (iii) bulk silicon back etching and (iv) oxide etching using siliconmicromachining technology. The electrochemical etching parameters were chosento form arrays of straight pores with a diameter of about 250 nm, a length of30 µm and interporedistances of 1 and 1.4 µm. The back side of the pore arrays was etched in potassium hydroxide and tetramethylammonium hydroxide. Finally, the inside of the pores was thermally oxidized to yieldSiO2 capillary arrays. The present method could allow the fabrication of capillaries withfurther smaller dimensions by increasing the thermally grown oxide thickness.