CHALLENGES IN ELECTRON-CYCLOTRON-RESONANCE PLASMA-ETCHING OF LINBO3 SURFACE FOR FABRICATION OF RIDGE OPTICAL WAVE-GUIDES

Ridge-shaped optical waveguides are promising structures to provide br oadband characteristics for LiNbO3 (LN) based optoelectronic devices. In this regard, electron cyclotron resonance plasma etching with fluor ocarbons have been commonly applied in the preparation of ridge wavegu ides, 3-5 mu m in height, but certain fabrication problems need invest igation and clarification. The etched LN surface was found to be cover ed with LiF leading to a weak adhesive strength for the overlayer, suc h as a SiO2 film, over the ridge waveguides. When CF4 etchant was used , a notch appeared along the foot of the ridge waveguides. The notch w as a possible origin for the chipping of the waveguides, Such an undes irable notch was found to be prevented by the use of a CHF3 etchant. H ere, these inevitable problems during the plasma etching of the LN wer e presented and discussed. (C) 1998 American Vacuum Society. [S0734-21 01(98)11204-6].