Optical semiconductor device, optical transmitter module, optical module, and optical transmission equipment, and method for manufacturing thereof

1. An optical semiconductor device comprising:

a semiconductor substrate;

a semiconductor multilayer stacked on an upper surface side of the semiconductor substrate,

the semiconductor multilayer having a mesa structure extending along a light emitting direction, and

the semiconductor multilayer being configured to emit light from an exit end surface;

an electrode pad portion for wire bonding,

the electrode pad portion being:

electrically connected to an upper surface of the mesa structure,

disposed on one side of the mesa structure, and

electrically connected to outside, and

a lower surface of the electrode pad portion being higher than the upper surface of the mesa structure; and

an electrode pad peripheral portion including a first rising surface and a second rising surface,

the first rising surface being in contact with an outer edge of the electrode pad portion on the exit end surface and rising along a stacking direction from the electrode pad portion, and

the second rising surface being in contact with the outer edge of the electrode pad portion on an opposite side of the exit end surface and rising along the stacking direction from the electrode pad portion.

2. The optical semiconductor device according to claim 1 , wherein the electrode pad peripheral portion surrounds the outer edge of the electrode pad portion in plan view.

3. The optical semiconductor device according to claim 1 , wherein the electrode pad peripheral portion further includes a flat surface outwardly in contact with the first rising surface.

4. The optical semiconductor device according to claim 3 , wherein the flat surface is a first flat surface; and

wherein the electrode pad peripheral portion further includes a second flat surface outwardly in contact with the second rising surface.

5. An optical transmitter module comprising:

the optical semiconductor device of claim 1 .

6. An optical module comprising:

the optical transmitter module of claim 5 ; and

an optical receiver module.

7. An optical transmission equipment on which the optical module of claim 6 is mounted.

8. A method for manufacturing an optical semiconductor device, the method comprising:

stacking a semiconductor multilayer on a semiconductor substrate;

forming a recess by removing a portion of the semiconductor multilayer including a region to be an electrode pad portion;

coating a resin on the recess with a spin coater to form a step in the resin;

forming an electrode pad portion on the resin; and

forming an electrode pad peripheral portion on the resin,

the electrode pad peripheral portion including:

a first rising surface in contact with an outer edge of the electrode pad portion on a first surface side and rising along a stacking direction from the electrode pad portion, and

a second rising surface being in contact with the outer edge of the electrode pad portion on a second surface side, opposite the first surface side, and rising along the stacking direction from the electrode pad portion.

9. The method according to claim 8 , wherein removing the portion of the semiconductor multilayer including the region to be the electrode pad portion comprises:

performing wet etching to remove the portion of the semiconductor multilayer including the region to be the electrode pad portion.

10. The method according to claim 8 , further comprising:

forming a passivation film on the optical semiconductor device based on forming the recess; and

wherein coating the resin on the recess comprises:

coating the resin on the passivation film after forming the passivation film on the optical semiconductor device.

11. The method according to claim 10 , further comprising:

forming, after coating the resin on the passivation film, a resist mask covering the region to be the electrode pad portion.

12. The method according to claim 11 , further comprising:

etching, after forming the resist mask, the resin to remove the resin from another region of the optical semiconductor device.

13. The method according to claim 12 , further comprising:

removing the resist mask based on etching the resin; and

wherein forming the electrode pad portion comprises:

forming the electrode pad portion after removing the resist mask.

14. The method according to claim 8 , wherein forming the electrode pad peripheral portion comprises:

forming the electrode pad peripheral portion to surround the outer edge of the electrode pad portion in plan view.

15. The method according to claim 8 , wherein the electrode pad peripheral portion further includes a flat surface outwardly in contact with the first rising surface.

16. The method according to claim 15 , wherein the flat surface is a first flat surface; and

wherein the electrode pad peripheral portion further includes a second flat surface outwardly in contact with the second rising surface.

17. The method according to claim 8 , further comprising:

forming a ridge structure by removing other portions of semiconductor multilayer.

18. The method according to claim 17 , further comprising:

forming a passivation film on the optical semiconductor device after forming the recess and the ridge structure; and

wherein coating the resin on the recess comprises:

coating the resin on the passivation film after forming the passivation film on the optical semiconductor device.

19. The method according to claim 18 , further comprising:

forming, after coating the resin on the passivation film, a first resist mask covering the region to be the electrode pad portion;

etching, after forming the first resist mask, the resin until an upper surface of the ridge structure appears;

removing, after etching the resin, the first resist mask;

forming, after removing the first resist mask, a second resist mask;

removing, after forming the second resist mask, the resin from both sides of the ridge structure;

removing, after removing the resin from both sides of the ridge structure, the second resist mask; and

removing a portion of the passivation film from the upper surface of the ridge structure; and

wherein forming the electrode pad portion comprises:

forming the electrode pad portion after removing the portion of the passivation film from the upper surface of the ridge structure.

20. An optical semiconductor device, comprising:

a semiconductor substrate;

a semiconductor multilayer stacked on an upper surface side of the semiconductor substrate,

wherein the semiconductor multilayer has a mesa structure extending along a light emitting direction, and

wherein the semiconductor multilayer is configured to emit light from an exit end surface;

an electrode pad portion for wire bonding,

wherein the electrode pad portion is:

electrically connected to an upper surface of the mesa structure,

disposed on one side of the mesa structure, and

electrically connected to outside,

wherein a lower surface of the electrode pad portion is higher than the upper surface of the mesa structure,

wherein the semiconductor multilayer has a recess obtained by partially removing a region of the semiconductor multilayer associated with the electrode pad portion, and

wherein a resin is disposed between the electrode pad portion and the recess; and

an electrode pad peripheral portion including a rising surface,

wherein the rising surface is in contact with an outer edge of the electrode pad portion on the exit end surface and rising along a stacking direction from the electrode pad portion.