CHF3-REACTIVE ION ETCHING FOR WAVE-GUIDES

The most favourable technological process to obtain Si/SiO2/PSG/SiO2-t ype waveguides by reactive ion etching has been developed. Preliminary experiments to find suitable gaseous mixtures to etch at higher etchi ng rates, as well as to obtain higher selectivities against photoresis t mask, have been designed. The use of SF6 in different experimental c onditions has shown an unfeasible etching process due to similar photo resist/oxide etch rates. On the other hand, higher selectivities have been obtained when CHF3 Was Used. Finally, a photoresist hardening ste p based on an ionic implantation technique has been added to the CHF3- etching process to avoid the erosion of the mask.