PLANARIZATION AND FABRICATION OF BRIDGES ACROSS DEEP GROOVES OR HOLESIN SILICON USING A DRY FILM PHOTORESIST FOLLOWED BY AN ETCH BACK

A technique is presented that provides planarization after a very deep etching step in silicon. This offers the possibility for not only res ist spinning and layer patterning but also for realization of bridges and cantilevers across deep grooves or holes. The technique contains a standard dry film lamination step to cover a wafer with a 38 mu m thi ck foil. Next the foil is etched back to the desired thickness of a fe w micrometres. This thin film facilitates resist spinning and high-res olution patterning. The planarization method is demonstrated by the fa brication of aluminium bridges across a deep groove in silicon.