Patent ID: 6231771
Filing Date: 2001-05-15
Classification: G02B

Abstract:
A process for treating a waveguide structure comprising:a silicon substrate with an integrally formed rib waveguide, the waveguide comprising an end portion with a facet, the end portion overhanging the silicon substrate and having an oxide layer on its underside protruding from the facet of the waveguide, and a nitride layer extending over the upper surface of the waveguide and the facet, the process comprising:i) carrying out an oxide etch step to remove the oxide layer from the underside;ii) carrying out an oxide growth step to form a new oxide layer on exposed silicon on the underside, said new oxide layer terminating at the facet;iii) carrying out a nitride etch step to remove the nitride layer; andiv) depositing a new nitride layer extending over the upper surface and facet without protruding beyond the facet, such that silicon nitride is formed on the facet.