Optical hybrid integrated device and method of making the same

Abstract

The surface area of a rectangular semiconductor substrate (,), which is used a reference plane, is composed of three regions arranged side by side in its lengthwise direction. A first one of the regions has a concavity (,) formed leaving opposite marginal portions of the region as banks (,), aid solder-coated pads (,) and alignment marks (,) are formed by metal thin films on the top surfaces of the banks. In a second region an electrode (,) is formed adjacent the first region and a semiconductor optical element (PD,) is mounted on the electrode with an active layer (,) of the former facing downward. An under-clad layer (,), acore (,), a height adjustment layer (,) and an over-clad layer (,), which constitute an optical waveguide, are formed over the surface of a second substrate, and the over-clad layer overlying both marginal portions of the second substrate is removed to expose the height adjustment layer to form terraces (,) corresponding to the banks. Solder-coated pads (,) and alignment marks (,) are formed by metal films on the terraces, and the solder-coated pads (,) and (,) are soldered to each other with the banks and the terraces positioned using the alignment marks (,) and (,). The thickness of the height adjustment layer (,) is predetermined so that the core and the semiconductor active layer (,) lie at the same vertical position relative to the reference plane.