Low drift planar waveguide grating sensor and method for manufacturing same

• US 7,218,802 B1
• Filed: 11/30/2005
• Issued: 05/15/2007
• Est. Priority Date: 11/30/2005
• Status: Expired due to Fees

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Bellman, Robert A., Wang, Chuan-che
• Primary Examiner(s): LEUNG, QUYEN PHAN
• Application Number:
  US11/292,400
• Publication Number:
  US 20070122077A1
• Time in Patent Office: 531 Days
• Field of Search: 385/12, 385/14, 385/37, 385/129, 385/130, 385/131, 385/141
• US Class Current: 385/12
• CPC Class Codes: B01L 2300/0654 Lenses; Optical fibres
• CPC Class Codes: B01L 2300/0829 Multi-well plates; Microtitration plates
• CPC Class Codes: B01L 3/5085 for multiple samples, e.g. microtitration plates
• CPC Class Codes: G01N 21/253 for batch operation, i.e. multisample apparatus analytical automats G01N35/00
• CPC Class Codes: G01N 21/7743 the reagent-coated grating coupling light in or out of the waveguide
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: G02B 5/1809 with pitch less than or comparable to the wavelength
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/1221 made from organic materials
• CPC Class Codes: G02B 6/13 Integrated optical circuits characterised by the manufacturing method

Abstract

A planar waveguide grating (PWG) sensor is described herein which exhibits a low signal drift and an enhanced sensitivity due to the use of a fully dense silicon-rich nitride surface layer. In the preferred embodiment, the silicon rich silicon nitride surface layer has a composition which includes Si and N, and optionally H, Ge and/or O, where a Si/N atomic ratio is greater than 0.75. In addition, the silicon rich nitride surface layer has a refractive index that is greater than 2.45 and less than 3.2 at a wavelength of operation. A method is also described herein for manufacturing the PWG sensor with acceptable costs and high yields by utilizing well known semiconductor processes and tools.

Claims

1. A planar waveguide grating (PWG) sensor comprising a silicon rich silicon nitride surface layer which has at least one of the following:

(1) a composition which includes at least Si and N where a Si/N atomic ratio is greater than 0.75; and

(2) a refractive index that is greater than 2.45 and less than 3.2 at a wavelength of operation.

2. The PWG sensor of claim 1, wherein said silicon rich silicon nitride surface layer has a composition that further includes H, Ge, and/or O.

3. The PWG sensor of claim 1, wherein said silicon rich silicon nitride surface layer has a thickness that is greater than 70 nm which is sufficient to form a waveguide.

4. The PWG sensor of claim 3, wherein said waveguide is formed by said silicon rich silicon nitride surface layer which is deposited by using one of the following:

a PECVD technique;

a LPCVD technique;

a SACVD technique;

an APCVD technique, or

a PVD technique which includes;

a sputtering technique;

an e-beam evaporation technique; and

an evaporation technique.

5. The PWG sensor of claim 1, further comprising a waveguide layer which has a thickness sufficient to form a monomode waveguide and a refractive index that is greater than 2.0 at the wavelength of operation.

6. The PWG sensor of claim 5, wherein said silicon rich nitride surface layer is deposited over said waveguide layer by using one of the following:

a sol-gel technique;

a spin on glass technique;

a CVD technique which includes;

a PECVD technique;

a LPCVD technique;

a SACVD technique;

or

an APCVD technique;

or

a PVD technique which includes;

a sputtering technique;

an e-beam evaporation technique; and

an evaporation technique.

7. The PWG sensor of claim 1, further comprising a <

1 micron thick oxide cladding layer which has a composition of Si, O, F, and optionally H, Ge, B, P and/or N, and has a refractive index that is less than 1.45 at the wavelength of operation.

8. The PWG sensor of claim 7, wherein said <

1 micron thick oxide cladding layer is formed by using one of the following CVD techniques;

a PECVD technique;

a LPCVD technique;

a SACVD technique;

an APCVD technique, or

a PVD technique which includes;

a sputtering technique;

an e-beam evaporation technique; and

an evaporation technique.

9. The PWG sensor of claim 7, further comprising a surface grating structure which is formed in said oxide cladding layer.

10. The PWG sensor of claim 9, wherein said surface grating structure is formed by a photolithography process which uses an i-line or 248 nm stepper and reactive ion etch.

11. The PWG sensor of claim 9, wherein said surface grating structure is formed by a photolithography process uses an i-line or 248 nm stepper and wet etch.

12. The PWG sensor of claim 1, further comprising a substrate.

13. A microplate comprising:

a frame including a plurality of wells formed therein, each well incorporating a planar waveguide grating (PWG) sensor that includes;

a silicon rich silicon nitride surface layer which has at least one of the following;

(1) a composition which includes at least Si and N where a Si/N atomic ratio is greater than 0.75; and

(2) a refractive index that is greater than 2.45 and less than 3.2 at a wavelength of operation.

14. The microplate of claim 13, wherein said silicon rich silicon nitride surface layer has a composition that further includes H, Ge, and/or O.

15. The microplate of claim 13, wherein said silicon rich silicon nitride surface layer has a thickness that is greater than 70 nm which is sufficient to form a monomode waveguide.

16. The microplate of claim 13, wherein said silicon rich nitride surface layer is deposited over a waveguide layer which has a thickness sufficient to form a monomode waveguide and a refractive index that is greater than 2.0 at the wavelength of operation.

17. The microplate of claim 13, wherein said PWG sensor further comprising a cladding layer which has a composition of Si, O, F, and optionally H, Ge, B, P and/or N, and has a refractive index that is less than 1.45 at the wavelength of operation.

18. The microplate of claim 17, wherein said PWG sensor further comprising a surface grating structure which is formed in said cladding layer.

19. The microplate of claim 17, wherein said PWG sensor further comprising a substrate.

20. A method for producing a planar waveguide grating (PWG) sensor, said method comprising the steps of:

providing a substrate;

depositing, onto said substrate, a cladding layer;

forming, in said cladding layer, a surface grating structure;

depositing, onto said cladding layer and said surface grating structure, a waveguide layer which has a thickness sufficient to form a monomode waveguide; and

forming, onto said waveguide layer, a silicon rich silicon nitride surface layer which has at least one of the following;

(1) a composition which includes at least Si and N where a Si/N atomic ratio is greater than 0.75; and

(2) a refractive index that is greater than 2.45 and less than 3.2 at a wavelength of operation.

21. The method of claim 20, wherein said step of forming said silicon rich silicon nitride surface layer is performed by using one of the following:

a PECVD technique;

a LPCVD technique;

a SACVD technique;

an APCVD technique, or

a PVD technique which includes;

a sputtering technique;

an e-beam evaporation technique; and

an evaporation technique.

22. A method for producing a PWG sensor, said method comprising the steps of:

providing a substrate;

depositing, onto said substrate, a cladding layer;

forming, in said cladding layer, a surface grating structure;

depositing, onto said cladding layer and said surface grating structure, a silicon rich silicon nitride surface layer which has a thickness sufficient to form a monomode waveguide and which also has at least one of the following;

(1) a composition which includes at least Si and N where a Si/N atomic ratio is greater than 0.75; and

(2) a refractive index that is greater than 2.45 and less than 3.2 at a wavelength of operation.

23. The method of claim 22, wherein said waveguide is formed by said silicon rich silicon nitride surface layer which is deposited by using one of the following:

a PECVD technique;

a LPCVD technique;

a SACVD technique;

an APCVD technique, or

a PVD technique which includes;

a sputtering technique;

an e-beam evaporation technique; and

an evaporation technique.