Microchannels for BioMEMS devices

• US 7,799,656 B2
• Filed: 03/11/2008
• Issued: 09/21/2010
• 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: Wright, Patrick, Ouellet, Luc
• Primary Examiner(s): Lee; Hsien-ming
• Assistant Examiner(s): PARENDO, KEVIN A
• Application Number:
  US12/045,853
• Publication Number:
  US 20080299695A1
• Time in Patent Office: 924 Days
• Field of Search: 438/50, 438/456, 438/458, 438/780, 438/781, 438791-794, 257/E21.57
• US Class Current: 438/456
• 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 carrier wafer;

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

forming a patterned first photopolymer layer on said modified surface layer;

forming a patterned second photopolymer layer on a device wafer;

bonding the patterned first and second photopolymer layers of the carrier wafer and the device wafer together to form an integrated device by applying heat and pressure; and

applying heat to decompose said modified surface layer and thereby separate the carrier wafer from the device wafer.

2. A method as claimed in claim 1, wherein said carrier wafer and device wafer are silicon wafers.

3. A method as claimed in claim 1, wherein the silicon nitride layer is deposited by low pressure chemical vapor deposition at a temperature in a range from 750 to 900°

C.

4. A method as claimed in claim 1, wherein said patterned first and second photopolymer layers comprise a negative tone photopolymer.

5. A method as claimed in claim 1, wherein said carrier and device wafers when bonded together form microchannels.

6. A method as claimed in claim 5, wherein the patterned first photopolymer layer on the carrier wafer forms a lid portion of said microchannels and said patterned second photopolymer layer on the device wafer forms a base of said microchannels.

7. A method as claimed in claim 1, wherein after separation of said carrier wafer and said device wafer, said bonded patterned first and second photopolymer layers are subjected to hardening treatment.

8. 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 hydrofluoric acid to form a modified surface layer;

forming a patterned first photopolymer layer on said modified surface layer;

forming a patterned second photopolymer layer on a device wafer;

bonding said patterned first and second photopolymer layers together to form an integrated device containing the microchannels; and

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

9. A method as claimed in claim 8, wherein said patterned first photopolymer layer provides a lid portion of said microchannels, and said patterned second photopolymer layer provides a base portion of said microchannels.

10. A method as claimed in claim 8, wherein said patterned first and second photopolymer layers are stabilized by baking at a temperature not exceeding 95°

C. prior to bonding said patterned first and second photopolymer layers together.

11. A method as claimed in claim 8, wherein after bonding said patterned first and second photopolymer layers are subjected to hardening treatment.

12. A method as claimed in claim 8, wherein said patterned first and second photopolymer layers are bonded together by applying heat and pressure to said carrier and device wafers.

13. A method as claimed in claim 8, wherein the silicon nitride layer has a thickness lying in the range of 0.05 μ

m to 1.0 μ

m.

14. A method as claimed in claim 8, wherein the patterned second photopolymer layer deposited on the device wafer is deposited in separate steps as two photopolymer sublayers.

15. A method as claimed in claim 8, wherein the exposure to anhydrous hydrofluoric acid is carried out in the presence of an organic volatile component.

16. A method as claimed in claim 8, wherein said carrier and device wafers are silicon wafers.