Light absorption apparatus
A light absorption apparatus includes a substrate, a light absorption layer above the substrate on a first selected area, a silicon layer above the light absorption layer, a spacer surrounding at least part of the sidewall of the light absorption layer, an isolation layer surrounding at least part of the spacer, wherein the light absorption apparatus can achieve high bandwidth and low dark current.
1. A method for forming a light absorption apparatus, the method comprising:
forming a stopping layer atop a substrate;
forming an additional substrate layer atop the stopping layer;
forming a photosensitive structure above the additional substrate layer;
creating an opening on a backside of the substrate to expose a portion of the stopping layer; and
forming, through the opening on the backside of the substrate, a reflector layer below the photosensitive structure,
wherein the additional substrate layer comprises vertical holes in the exposed portion of the stopping layer.
2. The method of claim 1 , wherein the reflector layer is configured to reflect light into the photosensitive structure.
3. The method of claim 1 , wherein forming the reflector layer comprises:
forming a dielectric mirror layer below the exposed portion of the stopping layer; and
forming a metal mirror layer below the dielectric mirror layer.
4. The method of claim 1 , wherein the reflector layer is below the exposed portion of the stopping layer.
5. The method of claim 1 , further comprising:
before forming the reflector layer, removing at least a portion of the stopping layer.
6. The method of claim 5 , wherein forming the reflector layer comprises:
forming a dielectric mirror layer at a level of the portion of the stopping layer that is removed; and
forming a metal mirror layer below the dielectric mirror layer.
7. The method of claim 1 , wherein the reflector layer is at a same level as the exposed portion of the stopping layer.
8. The method of claim 1 , further comprising:
before forming the reflector layer, converting at least a portion of the stopping layer to another material.
9. The method of claim 8 , wherein the converting comprises an oxidation process, and wherein the another material is an oxide.
10. The method of claim 1 , wherein the stopping layer comprises one or more of:
a dielectric material including oxide or nitride, silicon carbide (SiC), carbon-doped silicon (Si), silicon germanium (SiGe), carbon-doped SiGe, or carbon-doped Ge.
11. The method of claim 1 , wherein forming the additional substrate layer comprises:
opening holes on the exposed portion of the stopping layer;
forming, from the backside of the substrate and through the opened holes, a seed layer of substrate material atop the stopping layer; and
forming remainder of the additional substrate layer atop the seed layer.
12. The method of claim 1 , further comprising:
before forming the photosensitive structure, forming a contamination protection layer on the backside of the substrate.
13. The method of claim 12 , wherein the contamination protection layer comprises oxide or nitride.
14. The method of claim 12 , further comprising:
removing at least a portion of the contamination protection layer on the backside of the substrate after forming the photosensitive structure.
15. A semiconductor fabrication system including one or more machines for fabricating a light absorption apparatus, the one or more machines configured to perform operations comprising:
forming a stopping layer atop a substrate;
forming an additional substrate layer atop the stopping layer;
forming a photosensitive structure above the additional substrate layer;
creating an opening on a backside of the substrate to expose a portion of the stopping layer; and
forming, through the opening on the backside of the substrate, a reflector layer below the photosensitive structure,
wherein the additional substrate layer comprises vertical holes in the exposed portion of the stopping layer.
16. The system of claim 15 , wherein the reflector layer is configured to reflect light into the photosensitive structure.
17. The system of claim 15 , wherein forming the reflector layer comprises:
forming a dielectric mirror layer below the exposed portion of the stopping layer; and
forming a metal mirror layer below the dielectric mirror layer.
18. The system of claim 15 , wherein the reflector layer is below the exposed portion of the stopping layer.
19. The system of claim 15 , the operations further comprising:
before forming the reflector layer, removing at least a portion of the stopping layer.
20. The system of claim 19 , wherein forming the reflector layer comprises:
forming a dielectric mirror layer at a level of the portion of the stopping layer that is removed; and
forming a metal mirror layer below the dielectric mirror layer.
21. The system of claim 15 , wherein the reflector layer is at a same level as the exposed portion of the stopping layer.
22. The system of claim 15 , the operations further comprising:
before forming the reflector layer, converting at least a portion of the stopping layer to another material.
23. The system of claim 22 , wherein the converting comprises an oxidation process, and wherein the another material is an oxide.
24. The system of claim 15 , wherein the stopping layer comprises one or more of: a dielectric material including oxide or nitride, silicon carbide (SiC), carbon-doped silicon (Si), silicon germanium (SiGe), carbon-doped SiGe, or carbon-doped Ge.
25. The system of claim 15 , wherein forming the additional substrate layer comprises:
opening holes on the exposed portion of the stopping layer;
forming, from the backside of the substrate and through the opened holes, a seed layer of substrate material atop the stopping layer; and
forming remainder of the additional substrate layer atop the seed layer.
26. The system of claim 15 , the operations further comprising:
before forming the photosensitive structure, forming a contamination protection layer on the backside of the substrate.
27. The system of claim 26 , wherein the contamination protection layer comprises oxide or nitride.
28. The system of claim 26 , the operations further comprising:
removing at least a portion of the contamination protection layer on the backside of the substrate after forming the photosensitive structure.