Sealed semiconductor device
View Patent ↗A sealed semiconductor device having reduced delamination of the sealing layer in high temperature, high humidity conditions is disclosed. The semiconductor device includes a substrate and a stack of device layers on the substrate sealed with a sealing layer. The upper surface of a street area of the substrate is oxidized so that the oxidized region extends under the sealing layer. The presence of the oxidized region of the upper surface of the substrate helps reduce the delamination, because the oxidized surface does not react with water to the same extent as a non-oxidized surface. The semiconductor devices remain sealed after dicing through the street area because the oxidized surface does not delaminate.
1. A sealed semiconductor device comprising:
a single-material substrate having a top surface including adjacently disposed structure and street areas;
a semiconductor layer structure disposed on the structure area;
a sealing layer disposed on the semiconductor layer structure, for sealing the semiconductor layer structure;
wherein the street area includes an exposed oxidized portion of the substrate in contact with the sealing layer, for lessening delamination of the sealing layer from the substrate.
2. The semiconductor device of claim 1 , wherein the oxidized portion is at least 0.2 microns thick and contains at least 90% oxide.
3. The semiconductor device of claim 1 , wherein the oxidized portion has an uninterrupted crystalline structure of the substrate.
4. The semiconductor device of claim 3 , wherein the substrate comprises a semi-insulating (SI) substrate.
5. The semiconductor device of claim 1 , wherein the sealing layer comprises a dielectric passivation layer.
6. The semiconductor device of claim 5 , wherein the dielectric passivation layer comprises a silicon oxide or silicon nitride layer.
7. The semiconductor device of claim 1 , wherein the street area is recessed into the substrate, so that a vertical step exists between the structure and the street areas.
8. The semiconductor device of claim 7 , wherein the oxidized portion extends up the vertical step.
9. The semiconductor device of claim 7 , wherein the sealing layer extends up the vertical step.
10. The semiconductor device of claim 1 , further comprising a groove in the substrate between the structure area and the street area, wherein the sealing layer extends along walls of the groove.
11. The semiconductor device of claim 1 , wherein the sealing layer overlaps the oxidized portion.
12. The semiconductor device of claim 1 , wherein the oxidized portion extends to an edge of the substrate.
13. The semiconductor device of claim 1 , wherein the semiconductor layer structure comprises a mesa structure.
14. The semiconductor device of claim 1 , wherein the semiconductor device comprises a PIN photodiode or a laser diode.
15. A method of manufacturing the semiconductor device of claim 1 , comprising:
(a) providing the semiconductor layer structure disposed on the structure area of the top surface of the single-material substrate;
(b) depositing the sealing layer on top of the semiconductor layer structure;
(c) patterning the sealing layer to expose the street area of the top surface of the substrate; and
(d) oxidizing the street area, so as to obtain the oxidized portion, in contact with the sealing layer patterned in step (c).
16. The method of claim 15 , further comprising etching a vertical step or a groove in the substrate at the boundary between the street and the structure areas, for the sealing layer and/or the oxidized portion to extend up the vertical step or along walls of the groove.
17. The method of claim 15 , wherein in step (d), the oxidizing is performed by anodizing, and a duration of anodizing and/or an anodizing current are selected so as to cause the oxidized portion to extend beneath the sealing layer.
18. A method for lessening delamination of a sealing layer for sealing a semiconductor layer structure disposed on a single-material substrate, the method comprising:
(a) coating the semiconductor layer structure with a sealing layer;
(b) patterning the sealing layer to open a street area on the single-material substrate; and
(c) oxidizing the street area opened in step (b), so as to form in the street area an exposed oxidized portion of the substrate, so that the sealing layer is in contact with the oxidized portion.
19. The method of claim 18 , wherein step (c) comprises anodizing the substrate to oxidize the exposed portion of the street area.
20. The method of claim 19 , wherein in step (c), a duration of anodizing and/or an anodizing current are selected so as to cause the oxidized portion to extend beneath the sealing layer.