Fabrication of microsieves with sub-micron pore size by laser interferencelithography

Laser interference lithography is a low-cost method for the exposure of lar ge surfaces with regular patterns. Using this method, microsieves with a po re size of 65 nm and a pitch of 200 nm have been fabricated. The pores are formed by inverting a square array of photoresist posts with a chromium lif t-off process and by subsequent reactive-ion etching using the chromium as an etch mask. The method has wider process latitude than direct formation o f holes in the resist layer and the chromium mask allows for etching of por es with vertical sidewalls.