US5841931A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods of forming polycrystalline semiconductor waveguides for optoelectronic integrated circuits, and devices formed thereby
Assignee: Massachusetts Institute of Technology
•
Filing: 1996-11-26
•
Granted: 1998-11-24
•
Expires: 2016-11-26
Abstract
Abstract Methods of forming polycrystalline semiconductor waveguides include the steps of forming a first cladding layer (e.g., SiO2) on a substrate (e.g., silicon) and then forming a polycrystalline semiconductor layer (e.g., poly-Si) on the first cladding layer using a direct deposition technique or by annealing amorphous silicon (a-Si) to form a polycrystalline layer, for example. The deposited polycrystalline semiconductor layer can then be polished at a face thereof to have a root-mean-square (RMS) surface roughness of less than about 6 nm so that waveguides patterned therefrom have loss ratings of better than 35 dB/cm. The polished polycrystalline semiconductor layer is then preferably etched in a plasma to form a plurality of polycrystalline strips. A second cladding layer is then formed on the polycrystalline strips to form a plurality of polycrystalline waveguides which provide relatively low-loss paths for optical communication between one or more optoelectronic devices coupled thereto. The annealed amorphous silicon layer or deposited polycrystalline layer can also be hydrogenated by exposing the second cladding layer to a hydrogen containing plasma at a temperature and pressure of about 350 DEG C. and 0.16 mTorr, respectively, and for a duration in a range between about 30 and 60 minutes. This further improves the loss ratings of the waveguides to about 15 dB/cm or less.
Inventors
- 👤 James S. Foresi
- 👤 Anu M. Agarwal
- 👤 Marcie R. Black
- 👤 Debra M. Koker
- 👤 Lionel C. Kimerling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:22
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/10; G02B6/12; G02B6/12004; G02B6/122; G02B6/13; G02B6/132; G02B2006/12166; G02B2006/12169
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
85 words
A method of forming a semiconductor waveguide, comprising the steps of: forming a first cladding layer on a face of a substrate; forming a polycrystalline semiconductor layer on the first cladding layer; polishing the polycrystalline semiconductor layer at a face thereof extending opposite the first cladding layer; forming a second cladding layer on the polished face of the polycrystalline semiconductor layer; and coupling a source of optical energy to an interior of the polycrystalline semiconductor layer to propagate a signal having a first wavelength therein.
Claim 2
Independent Claim
85 words
A method of forming a semiconductor waveguide, comprising the steps of: forming a first cladding layer on a face of a substrate; forming a polycrystalline semiconductor layer on the first cladding layer; polishing the polycrystalline semiconductor layer at a face thereof extending opposite the first cladding layer; forming a second cladding layer on the polished face of the polycrystalline semiconductor layer; and coupling a source of optical energy to an interior of the polycrystalline semiconductor layer to propagate a signal having a first wavelength therein.
Claim 3
Dependent Claim
30 words
The method of claim 1, wherein said polishing step comprises polishing the face of the polycrystalline semiconductor layer to have a root-mean-square surface roughness of less than about 6 nm.
Claim 4
Dependent Claim
26 words
The method of claim 2, wherein said step of forming a polycrystalline semiconductor layer comprises forming a polycrystalline silicon layer containing grains smaller than 0.4 μm.
Claim 5
Dependent Claim
45 words
The method of claim 3, wherein said polishing step comprises polishing the polycrystalline silicon layer to remove sufficient defects from the face so that an energy loss of the signal at a first wavelength of less than about 1.55 μm is less than 35 dB/cm.
Claim 6
Dependent Claim
28 words
The method of claim 4, wherein said second cladding layer forming step is preceded by the step of exposing the polycrystalline silicon layer to a hydrogen containing plasma.
Claim 7
Dependent Claim
39 words
The method of claim 5, wherein said step of forming a second cladding layer comprises forming an electrically insulating layer having an index of refraction less than about 0.7 times an index of refraction of the polycrystalline silicon layer.
Claim 8
Dependent Claim
37 words
The method of claim 1, wherein said step of forming a polycrystalline semiconductor layer on the first cladding layer comprises depositing an amorphous semiconductor layer on the first cladding layer and annealing the deposited amorphous semiconductor layer.
Claim 9
Dependent Claim
30 words
The method of claim 7, wherein said step of depositing an amorphous semiconductor layer comprises depositing amorphous silicon at a temperature in a range between 475° C. and 600° C.
Claim 10
Dependent Claim
22 words
The method of claim 8, wherein said annealing step comprises annealing the deposited amorphous silicon at a temperature of about 600° C.
Claim 11
Dependent Claim
22 words
The method of claim 8, wherein said annealing step comprises annealing the deposited amorphous silicon at a temperature of about 1100° C.
Claim 12
Dependent Claim
32 words
The method of claim 2, wherein said step of forming a polycrystalline semiconductor layer comprises depositing a polycrystalline silicon layer at a temperature in a range between 625° C. and 700° C.
Claim 13
Dependent Claim
42 words
The method of claim 2, wherein said step of forming a polycrystalline semiconductor layer comprises depositing a polycrystalline silicon layer and etching the deposited polycrystalline silicon layer in a plasma containing SF 6 , HBr or CF 4 , or combinations thereof.
Claim 14
Dependent Claim
41 words
The method of claim 5, wherein said exposing step comprises exposing the polycrystalline silicon layer to a hydrogen containing plasma for a sufficient duration so that an energy loss of the signal at the first wavelength is less than 15 dB/cm.
Claim 15
Dependent Claim
39 words
The method of claim 13, wherein said exposing step comprises exposing the polycrystalline silicon layer to a hydrogen containing plasma at a temperature of about 350° C. for a duration in a range between about 30 and 60 minutes.
Claim 16
Dependent Claim
33 words
The method of claim 14, wherein said exposing step comprises exposing the polycrystalline silicon layer to a hydrogen containing plasma at a pressure of about 0.16 mTorr in an electron-cyclotron resonance plasma chamber.
Claim 17
Dependent Claim
28 words
The method of claim 4, wherein said second cladding layer forming step is followed by the step of exposing the second cladding layer to a hydrogen containing plasma.
Claim 18
Dependent Claim
39 words
The method of claim 16, wherein said exposing step comprises exposing the second cladding layer to a hydrogen containing plasma at a temperature of about 350° C. for a duration in a range between about 30 and 60 minutes.
Claim 19
Dependent Claim
33 words
The method of claim 17, wherein said exposing step comprises exposing the second cladding layer to a hydrogen containing plasma at a pressure of about 0.16 mTorr in an electron-cyclotron resonance plasma chamber.
Claim 20
Independent Claim
82 words
A method of forming a semiconductor waveguide, comprising the steps of: forming a first cladding layer on a face of a substrate; forming an amorphous semiconductor layer on the first cladding layer; annealing the amorphous semiconductor layer to convert the amorphous semiconductor layer to a polycrystalline semiconductor layer; forming a second cladding layer on the polycrystalline semiconductor layer; and coupling a source of optical energy to an interior of the polycrystalline semiconductor layer to propagate a signal having a first wavelength therein.
Claim 21
Independent Claim
82 words
A method of forming a semiconductor waveguide, comprising the steps of: forming a first cladding layer on a face of a substrate; forming an amorphous semiconductor layer on the first cladding layer; annealing the amorphous semiconductor layer to convert the amorphous semiconductor layer to a polycrystalline semiconductor layer; forming a second cladding layer on the polycrystalline semiconductor layer; and coupling a source of optical energy to an interior of the polycrystalline semiconductor layer to propagate a signal having a first wavelength therein.
Claim 22
Dependent Claim
29 words
The method of claim 19, further comprising the step of exposing the second cladding layer to a hydrogen containing plasma to incorporate hydrogen atoms into the polycrystalline semiconductor layer.
Claim 23
Dependent Claim
22 words
The method of claim 19, wherein said annealing step comprises annealing the amorphous semiconductor layer at a temperature of about 1100° C.
Claim 24
Independent Claim
70 words
A method of forming an optoelectronic integrated circuit, comprising the steps of: forming a layer of polycrystalline silicon on a semiconductor substrate; polishing a surface of the polycrystalline silicon layer to have a root-mean-square surface roughness of less than about 6 nm; patterning the polycrystalline silicon layer into a plurality of polycrystalline interconnect waveguides; and forming a plurality of optoelectronic devices optically coupled to interiors of respective polycrystalline interconnect waveguides.
Claim 25
Independent Claim
70 words
A method of forming an optoelectronic integrated circuit, comprising the steps of: forming a layer of polycrystalline silicon on a semiconductor substrate; polishing a surface of the polycrystalline silicon layer to have a root-mean-square surface roughness of less than about 6 nm; patterning the polycrystalline silicon layer into a plurality of polycrystalline interconnect waveguides; and forming a plurality of optoelectronic devices optically coupled to interiors of respective polycrystalline interconnect waveguides.
Claim 26
Dependent Claim
46 words
The method of claim 22, further comprising the step of forming a plurality of cladding layers on the plurality of polycrystalline interconnect waveguides, said cladding layers comprising a material having an index of refraction less than about 0.7 times an index of refraction of polycrystalline silicon.
Claim 27
Dependent Claim
35 words
The method of claim 22, wherein said cladding layer forming step is followed by the step of exposing the cladding layer to a hydrogen containing plasma to incorporate hydrogen atoms into the polycrystalline interconnect waveguides.
Claim 28
Dependent Claim
29 words
The method of claim 23, wherein said step of forming a layer of polycrystalline silicon comprises forming a layer of polycrystalline silicon containing grains therein smaller than 0.4 microns.
Claim 29
Dependent Claim
22 words
The method of claim 25, further comprising the step of forming a second plurality of polycrystalline interconnect waveguides on said cladding layers.
References Cited (Backward Citations)
US4111725A
Cited
US4862237A
Cited
US4716559A
Cited
US4715672A
Cited
US4728167A
Cited
US4781424A
Cited
US4787691A
Cited
US4789642A
Cited
US4978188A
Cited
US4884122A
Cited
US5035916A
Cited
US5508555A
Cited
US5051786A
Cited
US5059475A
Cited
US5064775A
Cited
US5279686A
Cited
US5263111A
Cited
US5238877A
Cited
US5274246A
Cited
US5394490A
Cited
US5303319A
Cited
US5528053A
Cited
US5681402A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-11-23 | 2002-05-25 | 2002-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-23 | 2006-05-25 | 2006-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-23 | 2010-05-25 | 2010-11-24 | $7700.00 | Window Closed / Lapsed |