Selective formation of porous silicon using silicon nitride and SU-8 masks for electroluminescence applications

Selective formation of porous silicon (PS) on both n-and p-type silicon wafers using silicon nitride deposited by PECVD and SU-8 photoresist is studied in this paper. Resistance of the silicon nitride to the HF etching can be enhanced by annealing at high temperature. The etching rate of the silicon nitride decreases from 50nm/min to 10nm/min when annealing the samples from 700°C to 950°C. The patterned PS areas were covered by a thin polyaniline layer doped with camphorsulphonic acid (CSA) to achieve a rectifying junction.