MICROMACHINED TITANIUM FOR HIGH PRESSURE MICROFLUIDIC APPLICATIONS

• US 20080142479A1
• Filed: 10/30/2006
• Published: 06/19/2008
• Est. Priority Date: 10/30/2006
• Status: Active Grant

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Beerling, Timothy, Yin, Hongfeng
• Granted Patent: US 8,501,029 B2
• Time in Patent Office: Days
• US Class Current: 216/58
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B81B 2201/058 Microfluidics not provided for in B81B2201/051 - B81B2201/054
• CPC Class Codes: B81C 1/00063 Trenches
• CPC Class Codes: B81C 2201/0132 Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling
• CPC Class Codes: G01N 30/6095 Micromachined or nanomachined, e.g. micro- or nanosize

Abstract

In accordance with the invention, a method for making microfluidic structures in bulk titanium is disclosed. Specific microfluidic structures include HPLC structures.

Claims

1. A method for creating a microfluidic structure in a titanium substrate comprising:

depositing a hard mask on said titanium substrate;

masking said hard mask with a photoresist layer;

patterning said photoresist layer;

performing an RIE etch on said masked hard mask to pattern said microfluidic structure on said hard mask;

removing said patterned photoresist layer; and

etching said microfluidic structure into said hard masked titanium substrate using a DRIE etch.

2. The method of claim 1 wherein said DRIE etch is selected from the group consisting of a chlorine-based DRIE etch and a chlorine-boron trichloride mixture based DRIE etch.

3. The method of claim 1 further comprising removing said patterned hard mask using fluorine based dry etch chemistries.

4. The method of claim 1 wherein said DRIE etch comprises using an inductively coupled plasma etcher with additional radio frequency power applied to a platen.

5. The method of claim 1 wherein said microfluidic structure comprises a Dean'"'"'s switch.

6. The method of claim 1 wherein said microfluidic structure comprises a capillary column.

7. The method of claim 1 further comprising:

providing a titanium sheet; and

attaching said titanium sheet to said titanium substrate using diffusion bonding.

8. The method of claim 7 wherein alignment holes are made in said titanium sheet.

9. The method of claim 8 wherein said alignment holes are made in said titanium sheet using electrical discharge machining.

10. The method of claim 7 wherein said titanium sheet is acid cleaned prior to diffusion bonding being performed.

11. The method of claim 7 wherein said diffusion bonding is performed at a temperature greater than about 750°

C. but less than about 883°

C.

12. A method for creating an integrated HPLC structure in a titanium substrate comprising:

depositing a hard mask on said titanium substrate;

applying a photoresist layer onto said hard mask;

patterning said photoresist layer;

performing an RIE etch on said masked hard mask to pattern said integrated HPLC structure on said hard mask;

removing said patterned photoresist layer; and

etching said integrated HPLC structure into said hard masked titanium substrate using a DRIE etch.

13. The method of claim 12 further comprising removing said patterned hard mask using fluorine based dry etch chemistries.

14. The method of claim 12 wherein said DRIE etch is selected from the group consisting of a chlorine-based DRIE etch and a chlorine-boron-trichloride mixture based DRIE etch.

15. The method of claim 12 further comprising:

spinning a first photoresist layer on said titanium substrate;

patterning said first photoresist layer; and

performing a shallow RIE etch to create a beadtrap.

16. The method of claim 12 wherein said integrated HPLC structure comprises a microfluidic structure selected from the group consisting of a separation column and an enrichment column.

17. The method of claim 12 further comprising:

providing a titanium sheet; and

attaching said titanium sheet to said titanium substrate using diffusion bonding.

18. The method of claim 12 wherein a polymer microfluidic circuit is attached to said integrated HPLC structure.

19. The method of claim 17 wherein a polymer based layer is laminated on said titanium sheet to accommodate attachment of an ultraviolet cell.

20. The method of claim 17 wherein said titanium sheet is acid cleaned prior to diffusion bonding being performed.