WAVEGUIDE STRUCTURE AND METHOD FOR FABRICATING THE SAME

• US 20140355929A1
• Filed: 05/30/2013
• Published: 12/04/2014
• Est. Priority Date: 05/30/2013
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: TSENG, Chun-Hao, CHEN, Hai-Ching, BAO, Tien-I, KUO, Ying-Hao
• Granted Patent: US 9,568,677 B2
• Time in Patent Office: Days
• US Class Current: 385/14
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/136 by etching
• CPC Class Codes: G02B 6/43 Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections

Abstract

Embodiments of forming a waveguide structure are provided. The waveguide structure includes a substrate, and the substrate has an interconnection region and a waveguide region. The waveguide structure also includes a trench formed in the substrate, and the trench has a sloping sidewall surface and a substantially flat bottom. The waveguide structure further includes a bottom cladding layer formed on the substrate, and the bottom cladding layer extends from the interconnection region to the waveguide region, and the bottom cladding layer acts as an insulating layer in the interconnection region. The waveguide structure further includes a metal layer formed on the bottom cladding layer on the sloping sidewall surface.

Claims

1. A waveguide structure, comprising:

a substrate, wherein the substrate has an interconnection region and a waveguide region;

a trench formed in the substrate, wherein the trench has a sloping sidewall surface and a substantially flat bottom;

a bottom cladding layer formed on the substrate, wherein the bottom cladding layer extends from the interconnection region to the waveguide region, and the bottom cladding layer acts as an insulating layer in the interconnection region; and

a metal layer formed on the bottom cladding layer on the sloping sidewall surface.

2. The waveguide structure as claimed in claim 1, further comprising:

a core layer formed on the bottom cladding layer in the waveguide region; and

a top cladding layer formed on the core layer, wherein a waveguiding structure is formed by the bottom cladding layer, the core layer and the top cladding layer.

3. The waveguide structure as claimed in claim 1, wherein a refractive index of the core layer is larger than that of the bottom cladding layer and the refractive index difference is in a range from about 0.02 to about 0.2.

4. The waveguide structure as claimed in claim 1, wherein the metal layer comprises aluminum (Al), copper (Cu), silver (Ag), gold (Au) or combinations thereof.

5. The waveguide structure as claimed in claim 1, wherein the sloping sidewall surface has a slope angle in a range from about 42 degree to about 48 degree.

6. The waveguide structure as claimed in claim 1, wherein the metal layer is further formed on the bottom cladding layer in the interconnection region.

7. The waveguide structure as claimed in claim 6, further comprising:

a redistribution layer (RDL) formed on the metal layer in the interconnection region.

8. The waveguide structure as claimed in claim 1, wherein the bottom cladding layer has a thickness in a range from 1 μ

m to about 10 μ

m.

9. An electro-optical device, comprising:

a substrate, wherein the substrate has an interconnection region and a waveguide region, and the waveguide region has a reflecting region and a wave-transmission region;

a trench formed in the substrate in the waveguide region;

a bottom cladding layer formed on the substrate, wherein the bottom cladding layer extends from the interconnection region through the reflecting region to the wave-transmission region and the bottom cladding layer acts as an insulating layer in the interconnection region;

a metal layer formed on the bottom cladding layer in the reflecting region; and

a laser diode mounted on the substrate; and

a photo diode mounted on the substrate.

10. The electro-optical device as claimed in claim 9, wherein the trench has a sloping sidewall surface, and the sloping sidewall surface has a slope angle in a range from about 42 degree to about 48 degree.

11. The electro-optical device as claimed in claim 9, further comprising:

a core layer formed on the bottom cladding layer in the waveguide region; and

a top cladding layer formed on the core layer, wherein a waveguiding structure is formed by the bottom cladding layer, the core layer and the top cladding layer.

12. The electro-optical device as claimed in claim 9, wherein the metal is further formed on the bottom cladding layer in the interconnection region.

13. The electro-optical device as claimed in claim 12, further comprising:

a redistribution layer (RDL) formed on the metal layer in the interconnection region.

14. The electro-optical device as claimed in claim 13, further comprising:

a bump structure formed between the redistribution layer (RDL) and the laser diode or the photo diode.

15. The waveguide structure as claimed in claim 9, further comprising:

a groove formed in the substrate and adjacent to the trench; and

an optical transfer device mounted in the groove.

16. A method for fabricating a waveguide structure, comprising:

providing a substrate, wherein the substrate has an interconnection region and a waveguide region;

forming a trench in the substrate, wherein the trench has a sloping sidewall surface and a substantially flat bottom;

forming a bottom cladding layer on the substrate in the interconnection region and the waveguide region; and

forming a metal layer on the bottom cladding layer on the sloping sidewall surface.

17. The method for fabricating a waveguide structure as claimed in claim 16, wherein the trench is formed by a wet etching etchants and the wet etching etchants comprises ethylene diamine pyrocatechol (EDP), potassium hydroxide (KOH) or tetramethyl ammonium hydroxide (TMAH).

18. The method for fabricating a waveguide structure as claimed in claim 17, an etch rate of the wet etching is in a range from about 0.2 micro to about 0.6 micro per minute.

19. The method for fabricating a waveguide structure as claimed in claim 16, further comprising:

forming the metal layer in the interconnection region; and

forming a redistribution layer (RDL) on the metal layer in the interconnection region.

20. The method for fabricating a waveguide structure as claimed in claim 19, wherein the redistribution layer (RDL) is formed by a plating method, physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD) or combinations thereof.