Arrayed micro needles for mechanical gene insertion

A novel approach to realize arrays of out of plane micro needles is given. The exterior shape of the micro needles is realized by dry etching using a RIE. The exterior shape is realized in silicon by dry etching using a SF6 and Argon plasma that achieve the progressive etching of the mask composed by silicon nitride and photoresist. The needles realized present an outer diameter of 900 nm for a height of about 7 microns. The needle is then realized by wet oxidation using a thin film of silicon nitride to perform a LOCOS at the end of the needle. The last step consists in selectively etch the Si3N4 and the silicon inside the needle by xenon difluoride.