Waveguide photodetector device and manufacturing method thereof

• US 20090324164A1
• Filed: 06/30/2008
• Published: 12/31/2009
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Block, Bruce A., Reshotko, Miriam R.
• Granted Patent: US 8,290,325 B2
• Time in Patent Office: Days
• US Class Current: 385/14
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: G02B 6/42 Coupling light guides with opto-electronic elements
• CPC Class Codes: G02B 6/4202 for coupling an active element with fibres without intermediate optical elements, e.g. fibres with plane ends, fibres with shaped ends, bundles
• CPC Class Codes: H01L 31/105 the potential barrier being of the PIN type
• CPC Class Codes: H01L 31/1085 the devices being of the Metal-Semiconductor-Metal [MSM] Schottky barrier type

Abstract

Embodiments of the present invention describe a waveguide-based photodetector device and its methods of fabrication. The waveguide photodetector device comprises a substrate having a cladding structure formed thereon. A waveguide element for receiving optical signals is disposed within the cladding structure. A portion of the waveguide element is encapsulated by a photodetector element that detects the optical signal received by the waveguide element and generates an electrical signal based on the optical signal. Encapsulating the waveguide element in the photodetector element improves coupling efficiency and enables a waveguide photodetector device with higher speeds and higher responsivity.

Claims

1. A method of forming a semiconductor device comprising:

providing a substrate;

forming a waveguide element on the substrate, wherein the waveguide element comprises a top surface and sidewalls, wherein the sidewalls extend from the top surface to the substrate;

forming a cladding layer onto the waveguide element and the substrate, wherein the cladding layer exposes the top surface of waveguide element and a portion of the sidewalls proximal to the top surface of waveguide element; and

forming a photodetector element on the waveguide element, wherein the photodetector element encapsulates the top surface of waveguide element and the portion of the sidewalls proximal to the top surface of waveguide element.

2. The method of claim 1, wherein forming the cladding layer onto the waveguide element and the substrate comprises:

depositing a layer of cladding material onto the waveguide element and the substrate; and

patterning the layer of cladding material to form the cladding layer.

3. The method of claim 2, wherein patterning the layer of cladding material to form the cladding layer comprises:

planarizing the layer of cladding material to form the cladding layer; and

selectively etching the cladding layer to form a trench thereon, wherein the trench exposes the top surface of waveguide element and the portion of the sidewalls proximal to the top surface of waveguide element.

4. The method of claim 3, wherein forming the photodetector element on the waveguide element comprises:

depositing a layer of photodetector material onto the cladding layer and trench, wherein the layer of photodetector material encapsulates the top surface and the portion of sidewalls proximal to top surface of waveguide element; and

planarizing the layer of photodetector material to form the photodetector element.

5. The method of claim 2, wherein patterning the layer of cladding material to form the cladding layer comprises selectively etching the layer of cladding material to form the cladding layer, wherein the cladding layer exposes the top surface of waveguide element and the portion of the sidewalls proximal to top surface of waveguide element.

6. The method of claim 5, wherein forming the photodetector element on the waveguide element comprises:

depositing a layer of photodetector material onto the cladding layer and the top surface and the portion of sidewalls of waveguide element; and

patterning the layer of photodetector material to form the photodetector element.

7. The method of claim 6, wherein patterning the layer of photodetector material to form the photodetector element comprises:

planarizing the layer of photodetector material; and

selectively etching the layer of photodetector material to form the photodetector element.

8. The method of claim 1, wherein forming the waveguide element on the substrate comprises:

depositing a layer of waveguide material onto the substrate; and

etching the layer of waveguide material to form the waveguide element.

9. The method of claim 1 further comprising:

forming a n-type region and a p-type region in opposite sides of the photodetector element; and

forming a metal contact on each n-type region and p-type region of the photodetector element.

10. The method of claim 9, wherein the n-type region and a p-type region in opposite sides of the photodetector element are formed by ion-implantation.

11. The method of claim 9, wherein forming the metal contact on each n-type region and p-type region of the photodetector element comprises:

depositing a layer of dielectric material on the photodetector element and cladding layer;

etching the layer of dielectric material to form openings therein, wherein the openings expose each of the n-type region and p-type region of the photodetector element;

depositing a metal layer onto the layer of dielectric material and openings; and

planarizing the metal layer to form the metal contact on each n-type region and p-type region of the photodetector element.

12. The method of claim 9, wherein the substrate comprises a layer of active devices coupled to the metal contact on each n-type region and p-type region of the photodetector element.

13. The method of claim 12, wherein the substrate further comprises a plurality of metal interconnects, and wherein the plurality of metal interconnects couple the layer of active devices to the metal contact on each n-type region and p-type region of the photodetector element.

14. The method of claim 1, wherein the cladding layer comprises silicon dioxide.

15. The method of claim 1, wherein the waveguide element comprises silicon or silicon nitride.

16. The method of claim 1, wherein the photodetector element comprises polycrystalline silicon or polycrystalline germanium.

17. A method of forming a semiconductor device comprising:

providing a substrate;

forming a waveguide element on the substrate, wherein the waveguide element comprises a top surface and sidewalls, wherein the sidewalls extend from the top surface to the substrate; and

forming a photodetector element on the waveguide element, wherein the photodetector element encapsulates the top surface and sidewalls of waveguide element.

18. The method of claim 17, wherein forming the photodetector element on the waveguide element comprises:

depositing a layer of photodetector material onto the waveguide element and substrate, wherein the layer of photodetector material encapsulates the top surface and sidewalls of waveguide element; and

patterning the layer of photodetector material to form the photodetector element.

19. The method of claim 18, wherein patterning the layer of photodetector material to form the photodetector element comprises:

planarizing the layer of photodetector material; and

selectively etching the layer of photodetector material to form the photodetector element.

20. The method of claim 17, wherein forming the waveguide element on the substrate comprises:

depositing a layer of waveguide material onto the substrate; and

etching the layer of waveguide material to form the waveguide element.

21. The method of claim 17 further comprising:

forming a n-type region and a p-type region in opposite sides of the photodetector element; and

forming a metal contact on each n-type region and p-type region of the photodetector element.

22. The method of claim 21, wherein the n-type region and a p-type region in opposite sides of the photodetector element are formed by ion-implantation.

23. The method of claim 21, wherein forming the metal contact on each n-type region and p-type region of the photodetector element comprises:

depositing a layer of cladding material on the photodetector element;

etching the layer of cladding material to form openings therein, wherein the openings expose each of the n-type region and p-type region of the photodetector element;

depositing a metal layer onto the layer of cladding material and openings; and

planarizing the metal layer to form the metal contact on each n-type region and p-type region of the photodetector element.

24. The method of claim 21, wherein the substrate comprises a layer of active devices coupled to the metal contact on each n-type region and p-type region of the photodetector element.

25. The method of claim 24, wherein the substrate further comprises a plurality of metal interconnects, and wherein the plurality of metal interconnects couple the layer of active devices to the metal contact on each n-type region and p-type region of the photodetector element.

26. The method of claim 17, wherein the waveguide element comprises silicon or silicon nitride.

27. The method of claim 17, wherein the photodetector element comprises polycrystalline silicon or polycrystalline germanium.

28. A method of forming a semiconductor device comprising:

providing a substrate;

forming a photodetector element on the substrate, the photodetector element having a trench formed thereon; and

forming a waveguide element on the trench of photodetector element, wherein the waveguide element comprises a top surface, a bottom surface, and sidewalls extending from the top surface to the bottom surface, and wherein the trench of photodetector element encapsulates the bottom surface and a portion each sidewalls proximal to bottom surface of waveguide element.

29. The method of claim 28, wherein the forming the photodetector element on the substrate comprises:

depositing a layer of photodetector material onto the substrate; and

etching the layer of photodetector material to form the photodetector element and trench.

30. The method of claim 28, wherein forming the waveguide element on the trench of photodetector element comprises:

depositing a layer of waveguide material onto the photodetector element and trench; and

etching the layer of waveguide material to form the waveguide element.

31. The method of claim 28 further comprising:

forming a n-type region and a p-type region in opposite sides of the photodetector element; and

forming a metal contact on each n-type region and p-type region of the photodetector element.

32. The method of claim 31, wherein the n-type region and a p-type region in opposite sides of the photodetector element are formed by ion-implantation.

33. The method of claim 31, wherein forming the metal contact on each n-type region and p-type region of the photodetector element comprises:

depositing a layer of cladding material onto the waveguide element and the photodetector element;

etching the layer of cladding material to form openings therein, wherein the openings expose each of the n-type region and p-type region of the photodetector element;

depositing a metal layer onto the layer of cladding material and openings; and

planarizing the metal layer to form the metal contact on each n-type region and p-type region of the photodetector element.

34. The method of claim 31, wherein the substrate further comprises a layer of active devices, and wherein the layer of active devices is coupled to the metal contact on each n-type region and p-type region of the photodetector element.

35. The method of claim 34, wherein the substrate further comprises a plurality of metal interconnects, and wherein the plurality of metal interconnects couple the layer of active devices to the metal contact on each n-type region and p-type region of the photodetector element.

36. The method of claim 28, wherein the waveguide element comprises silicon nitride.

37. The method of claim 28, wherein the photodetector element comprises polycrystalline silicon or polycrystalline germanium.

38. A semiconductor device comprising:

a substrate;

a cladding layer formed on the substrate;

a waveguide element for receiving optical signals disposed within the cladding layer, wherein the waveguide element comprises a first surface, a second surface, and sidewalls extending from the first surface to the second surface; and

a photodetector element disposed within the cladding layer and encapsulates the first surface and a portion of the sidewalls proximal to the first surface of waveguide element, wherein the photodetector element detects the optical signal received by the waveguide element and generates an electrical signal based on the optical signal.

39. The semiconductor device of claim 38 further comprising:

a n-type region and a p-type region formed in opposite sides of the photodetector element;

a first metal contact coupled to the n-type region of the photodetector element; and

a second metal contact coupled to the p-type region of the photodetector element.

40. The semiconductor device of claim 39, wherein the substrate further comprises a layer of active devices, wherein the layer of active devices is coupled to the first metal contact and second metal contact.

41. The semiconductor device of claim 40, wherein the substrate further comprises a plurality of metal interconnects, and wherein the plurality of metal interconnects couple the layer of active devices to the first metal contact and second metal contact.

42. The semiconductor device of claim 38, wherein the cladding layer comprises silicon dioxide.

43. The semiconductor device of claim 38, wherein the waveguide element comprises silicon or silicon nitride.

44. The semiconductor device of claim 38, wherein the photodetector element comprises polycrystalline silicon or polycrystalline germanium.