Semiconductor optical device and method for manufacturing the same
A semiconductor optical device may include a semiconductor substrate; a compound semiconductor layer on the semiconductor substrate; an additional insulating film on the pedestal portion of the compound semiconductor layer, the additional insulating film having an upper surface and a side surface at an inner obtuse angle between them; a passivation film covering the compound semiconductor layer and the additional insulating film except at least part of the mesa portion, the passivation film having a protrusion raised by overlapping with the additional insulating film; a mesa electrode on the at least part of the mesa portion; a pad electrode on the passivation film within the protrusion; and an extraction electrode on the passivation film, the extraction electrode being continuous within and outside the protrusion, the extraction electrode connecting the pad electrode and the mesa electrode, the extraction electrode being narrower in width than the pad electrode.
1. A semiconductor optical device, comprising:
a semiconductor substrate;
a compound semiconductor layer on the semiconductor substrate, the compound semiconductor layer having a mesa portion extending in a stripe shape in a first direction, the compound semiconductor layer having a pedestal portion adjacent to the mesa portion in a second direction perpendicular to the first direction;
an additional insulating film on the pedestal portion of the compound semiconductor layer, the additional insulating film having an upper surface and a side surface at an inner obtuse angle between the upper surface and the side surface;
a passivation film covering the compound semiconductor layer and the additional insulating film except at least part of the mesa portion, the passivation film having a protrusion raised by overlapping with the additional insulating film;
a mesa electrode on the at least part of the mesa portion;
a pad electrode on the passivation film within the protrusion; and
an extraction electrode on the passivation film, the extraction electrode being continuous within and outside the protrusion, the extraction electrode connecting the pad electrode and the mesa electrode, the extraction electrode being narrower in width than the pad electrode.
2. The semiconductor optical device of claim 1 , wherein the passivation film includes a first portion in contact with the upper surface of the additional insulating film, and a second portion in contact with the side surface of the additional insulating film and lower than the first portion.
3. The semiconductor optical device of claim 2 , wherein the first portion and the second portion are integrally continuous without a break entirely.
4. The semiconductor optical device of claim 2 , wherein the first portion and the second portion are at least partially separated.
5. The semiconductor optical device of claim 4 , wherein the first portion is completely separated from the second portion and is located within the upper surface of the additional insulating film.
6. The semiconductor optical device of claim 1 , wherein at least one of the passivation film or the additional insulating film is formed of some laminated layers.
7. The semiconductor optical device of claim 1 , wherein the passivation film is equivalent in thickness to the additional insulating film.