Method of making a microvalve

• US 5,238,223 A
• Filed: 06/16/1992
• Issued: 08/24/1993
• Est. Priority Date: 08/11/1989
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology, Robert Bosch GmbH
• Original Assignee: Massachusetts Institute of Technology, Robert Bosch GmbH
• Inventors: Huff, Michael A., Lober, Theresa, Schmidt, Martin A., Mettner, Michael
• Primary Examiner(s): CHAMBERS, A MICHAEL
• Application Number:
  US07/899,260
• Time in Patent Office: 434 Days
• Field of Search: 251/367, 251/368, 251/129.06
• US Class Current: 251/368
• CPC Class Codes: F15C 5/00 Manufacture of fluid circuit elements; Manufacture of assemblages of such elements integrated circuits
• CPC Class Codes: F16K 2099/0069 Bistable microvalves
• CPC Class Codes: F16K 2099/0074 using photolithography, e.g. etching
• CPC Class Codes: F16K 2099/008 Multi-layer fabrications
• CPC Class Codes: F16K 2099/0096 Fuel injection devices
• CPC Class Codes: F16K 99/0001 Microvalves microdevices B81B1/00; manufacture or treatment of devices or systems in or on a substrate B81C1/00; microfluidic structures B01L3/5027; micropumps F04B19/006
• CPC Class Codes: F16K 99/0005 Lift valves
• CPC Class Codes: F16K 99/0034 Operating means specially adapted for microvalves
• CPC Class Codes: F16K 99/0046 using magnets
• CPC Class Codes: F16K 99/0048 using piezoelectric means
• CPC Class Codes: F16K 99/0055 actuated by fluids
• CPC Class Codes: F16K 99/0061 actuated by an expanding gas or liquid volume

Abstract

A microvalve composed of multiple layers bonded together is distinguished by the fact that all layers are structured only from one side. Prior to bonding of a new layer to the preceding layer, the new layer is homogeneous or unstructured. Only after bonding of the new layer to the preceding layers or wafers is the newly-applied layer provided with a structure, by etching or other profiling method. This simplifies construction, and reduces manufacturing cost, of the microvalve. The valve can be used for either liquid or gaseous media. It is adapted for use, inter alia, as a fuel injection valve or as a pilot control stage of servo-valves used in anti-lock braking systems (ABS). A method of producing a sealed cavity with a residual gas pressure therein, which may have applications other than valve manufacture, is also disclosed.

Claims

1. Microvalve having a plurality of layers bonded together, including

a first wafer (3) which serves as a carrier layer;

a second wafer (5) bonded to said first wafer and formed with a central projection (21) defined by a surrounding first channel (13);

a third wafer (7) bonded to said second wafer (5) and including a valve plate (19) secured to said projection (21);

and a cover layer (9) bonded to said third wafer (7) and including an undersurface adapted to engage said valve plate (19);

and wherein each layer (3, 5, 7,

     9) has apertures (11, 13, 17, 23,

     25) formed therein from only one side thereof.

2. Microvalve according to claim 1, further comprising

a sealing shoulder (27) formed on an upper surface of said valve plate (19), spaced from a circumferential edge thereof, and adapted to engage said undersurface of said cover layer (9).

3. Microvalve according to claim 2, wherein

said sealing shoulder (27) has a height which is substantially less than a thickness of said valve plate (19).

4. Microvalve according to claim 1, wherein

a surface of said valve plate (19) adjacent said undersurface of said cover layer (9) is coated with a hard layer (29).

5. Microvalve according to claim 4, wherein said hard layer consists essentially of silicon nitride.

6. Microvalve according to claim 1, wherein

said cover layer (9) consists essentially of PYREX glass and all other layers (3, 5, 7) consist essentially of silicon.

7. Microvalve according to claim 1, wherein all of said layers (3, 5, 7, 9) consist essentially of silicon.

8. Microvalve according to claim 1, wherein

an insulating layer (33, 35) is provided on at least one of:

a surface of said first layer (3) adjacent said second layer (5) and

a surface of said second layer (5) adjacent said first layer (3).

9. Microvalve according to claim 1, wherein

an insulating layer (33, 35) is provided on at least one of:

a surface of said second layer (5) adjacent said third layer (7) and

a surface of said third layer (7) adjacent said second layer (5).

10. Microvalve according to claim 1, wherein at least one major surface of said first wafer (3) includes a doped layer (31).

11. Microvalve according to claim 1, wherein

an undersurface of said second wafer (5) includes a doped layer (45).