MICROCHANNELS FOR BioMEMS DEVICES

• US 20080299695A1
• Filed: 03/11/2008
• Published: 12/04/2008
• Est. Priority Date: 03/15/2007
• Status: Active Grant

• Current Assignee: Teledyne Digital Imaging, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: Dalsa Incorporated (Teledyne Technologies Incorporated)
• Inventors: Ouellet, Luc, Wright, Patrick
• Granted Patent: US 7,799,656 B2
• Time in Patent Office: Days
• US Class Current: 438/50
• CPC Class Codes: B81B 2201/06 Bio-MEMS
• CPC Class Codes: B81C 1/00071 Channels
• CPC Class Codes: B81C 2201/0191 Transfer of a layer from a carrier wafer to a device wafer

Abstract

A method is disclosed for making a MEMS device wherein anhydrous HF exposed silicon nitride is used as a temporary adhesion layer allowing the transfer of a layer from a Carrier Wafer to a Device Wafer.

Claims

1. A method of making a MEMS device, comprising:

depositing a silicon nitride layer on a first part;

chemically modifying said silicon nitride layer to form a modified surface layer subject to thermal decomposition into gaseous by-products;

forming a first structure on said modified surface layer;

forming a second structure on a second part;

bonding said first and second structures together to form a integrated device; and

applying heat to decompose said modified surface layer and thereby separate one of said parts from said bonded structures.

2. A method as claimed in claim 1, wherein said first and second parts are bonded by applying heat and pressure.

3. A method as claimed in claim 2, wherein said silicon nitride layer is chemically modified by exposure to anhydrous HF.

4. A method as claimed in claim 1, wherein said first and second parts comprise respectively a carrier wafer and a device wafer.

5. A method as claimed in claim 4, wherein said carrier wafer and device wafer are silicon wafers.

6. A method as claimed in claim 1, wherein the silicon nitride layer is deposited by LPCVD at a temperature ranging from 750 to 900°

C.

7. A method as claimed in claim 1, wherein said first and second structures are formed by depositing a photopolymer on said first and second parts respectively.

8. A method as claimed in claim 7, wherein the photopolymer on said first and second parts is masked and exposed to radiation to form said first and second structures.

9. A method as claimed in claim 8, wherein said photopolymer is a negative tone photopolymer.

10. A method as claimed in claim 8, wherein said first and second structures when bonded together form microchannels.

11. A method as claimed in claim 10, wherein the first structure forms a lid portion of said microchannels and said second structure forms a base of said microchannels.

12. A method as claimed in claim 1, wherein after separation of said parts, said bonded structures are subjected to further treatment to harden the structures.

13. A method as claimed in claim 12, wherein the structures are made of polymerizable material, and said further treatment results in the polymerization of said material.

14. A method as claimed in claim 13, wherein said polymerizable material is a photopolymer.

15. A method of forming a MEMS device containing microchannels, comprising:

depositing a silicon nitride layer on a carrier wafer;

modifying a surface portion of said silicon nitride layer by exposure to anhydrous HF to form a modified surface layer;

forming a patterned first structure on said modified surface layer;

forming a patterned second structure on a device wafer;

bonding said first and second structure together to form microchannels; and

releasing said carrier wafer by heating said structures to decompose said modified surface layer.

16. A method as claimed in claim 15, wherein said first structure provides a lid portion of said microchannels, and said second structure provides a base portion of said microchannels.

17. A method as claimed in claim 16, wherein said first and second structures are formed in deposited photopolymer layers.

18. A method as claimed in claim 17, wherein said deposited layers are baked at a temperature not exceeding 95°

C. for stabilization prior to forming said patterned structures.

19. A method as claimed in claim 17, wherein said photopolymer layers are subjected to radiation through mask to define said structures.

20. A method as claimed in claim 19, wherein after bonding said structures are subjected to heat treatment to harden the microchannels.

21. A method as claimed in claim 15, wherein said first and second structures are bonded together by applying heat and pressure to said wafers.

22. A method as claimed in claim 15, wherein the thickness of the silicon nitride layer lies in the range of 0.05 μ

m to 1.0 μ

m.

23. A method as claimed in claim 17, wherein the photopolymer layer deposited on the device wafer is deposited in separate steps as two photopolymer sublayers.

24. A method as claimed in claim 15, wherein the exposure to anhydrous HF is carried out in the presence of an organic volatile component.

25. A method as claimed in claim 15, wherein said wafers are silicon wafers.