Simple fabrication method for vertical taper using tensile stress-induced mask and selective etching technique

A vertical taper structure has a lot of applications for optoelectronic integrated circuits (OEICs). In vertical taper structures, the thickness of the layer must be gradually changed along the device so that special techniques are required. We report on a simple fabrication method for a vertical taper using a tensile stress-induced mask and selective etching technique. We discovered that SiO/sub 2//Cr/Au with a tensile stress could be used for making the vertical taper. Also, the profile could be adjusted by controlling the etching process parameter. For its application, we are making a spot size converter for efficient coupling between a fiber and optical devices.