Arrayed semiconductor device, optical transmission module, optical module, and method for manufacturing thereof

1. A manufacturing method of an arrayed semiconductor optical device, the arrayed semiconductor optical device comprising a plurality of semiconductor optical devices comprising a first semiconductor optical device and a second semiconductor optical device, the method comprising:

forming a first conductivity type semiconductor layer on a semiconductor substrate;

forming a plurality pairs of masks for the plurality of semiconductor optical devices on an upper side of the first conductivity type semiconductor layer, each of the plurality pairs of masks being disposed sandwiching a region for the corresponding semiconductor optical device, the plurality pairs of masks comprising a first pair of masks for the first semiconductor optical device and a second pair of masks for the second semiconductor optical device;

forming a first semiconductor layer comprising a multiple quantum well layer entirely over the semiconductor substrate;

removing the plurality pairs of masks and portions of the first semiconductor layer located between adjacent pairs of masks out of the plurality pairs of masks;

forming a mesa etching stop layer and a second semiconductor layer in this order entirely over the semiconductor substrate so as to cover the first semiconductor layer, the second semiconductor layer comprising a grating layer:

forming gratings for the plurality of semiconductor optical devices by processing the grating layer, respectively;

forming a second conductivity type clad layer and a second conductivity type contact layer in this order entirely over the semiconductor substrate;

forming a plurality of mesa masks on an upper surface of the second conductivity type contact layer; and

performing an etching using the plurality of mesa masks to remove regions of the second conductivity type contact layer and the second conductivity type clad layer on both sides of the plurality of mesa masks, respectively,

wherein in the forming a first semiconductor layer, a layer thickness of the first semiconductor layer of the first semiconductor optical device is thinner than a layer thickness of the first semiconductor layer of the second semiconductor optical device due to spacings of the first and second pairs of masks and mask widths of the first and second pairs of the masks, and

wherein in the forming a mesa etching stop layer and a second semiconductor layer, a first mesa structure including the first semiconductor layer and the mesa etching stop layer is formed for each of the plurality of semiconductor optical devices, respectively.

2. The manufacturing method of the arrayed semiconductor optical device according to claim 1 , the forming gratings comprising:

forming a cap layer on an upper surface of the grating layer;

forming a plurality of grating pattern masks on an upper surface of the cap layer for the plurality of semiconductor optical devices, respectively;

etching the cap layer using the plurality of grating patter masks to remove regions of the grating layer where the plurality of grating pattern masks are not disposed;

removing the plurality of grating pattern masks;

etching the grating layer using the cap layer as masks to form the gratings,

wherein in the etching the grating layer, a second mesa structure of the second semiconductor layer is formed for each of the plurality of semiconductor optical devices.

3. The manufacturing method of the arrayed semiconductor optical device according to claim 2 , wherein in the performing an etching using the plurality of mesa masks, a third mesa structure including the second conductivity type clad layer and the second conductivity type contact layer is formed for each of the plurality of semiconductor optical devices.

4. The manufacturing method of the arrayed semiconductor optical device according to claim 3 , the manufacturing method further comprising:

after the performing an etching using the plurality of mesa masks,

removing regions of the mesa etching stop layer outside of the first mesa structures of the plurality of semiconductor optical devices;

removing partial regions of the first conductivity type semiconductor layer exposed between adjacent semiconductor optical devices out of the plurality of semiconductor optical devices, respectively; so that the first conductivity type layer of the plurality of semiconductor optical device is electrically isolated each other; and

forming a first conductivity side electrode and a second conductivity side electrode, the first conductivity side electrode being electrically connected with the first conductivity type semiconductor layer and the second conductivity side electrode being electrically connected with the second conductivity type contact layer.

5. The manufacturing method of the arrayed semiconductor optical device according to claim 3 ,

wherein the first mesa structure is wider than the second mesa structure and the second mesa structure is wider than the third mesa structure for each of the plurality of semiconductor optical devices.

6. The manufacturing method of the arrayed semiconductor optical device according to claim 4 ,

wherein the first mesa structure is wider than the second mesa structure and the second mesa structure is wider than the third mesa structure for each of the plurality of semiconductor optical devices.