Method of manufacturing vibrating micromechanical structures

• US 20060207087A1
• Filed: 03/21/2005
• Published: 09/21/2006
• Est. Priority Date: 03/21/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Jafri, Ijaz H., Klein, Jonathan L., Magendanz, Galen P.
• Granted Patent: US 7,406,761 B2
• Time in Patent Office: Days
• US Class Current: 29/831
• CPC Class Codes: B81B 2201/0271 Resonators; ultrasonic resonators
• CPC Class Codes: B81C 1/00142 Bridges deformable micromirrors G02B26/0841
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B81C 2203/036 Fusion bonding
• CPC Class Codes: B81C 2203/051 Active alignment, e.g. using internal or external actuators, magnets, sensors, marks or marks detectors
• CPC Class Codes: H03H 3/0072 of microelectro-mechanical resonators or networks micromembranes or microbeams B81B2203/01; manufacture of microstructural devices in general B81C
• CPC Class Codes: H03H 9/2447 Beam resonators H03H9/2468 takes precedence
• CPC Class Codes: H03H 9/462 Microelectro-mechanical filters
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49156 with selective destruction of conductive paths
• CPC Class Codes: Y10T 29/49826 Assembling or joining
• CPC Class Codes: Y10T 29/49861 Sizing mating parts during final positional association

Abstract

A method for fabrication of single crystal silicon micromechanical resonators using a two-wafer process, including either a Silicon-on-insulator (SOI) or insulating base and resonator wafers, wherein resonator anchors, a capacitive air gap, isolation trenches, and alignment marks are micromachined in an active layer of the base wafer; the active layer of the resonator wafer is bonded directly to the active layer of the base wafer; the handle and dielectric layers of the resonator wafer are removed; viewing windows are opened in the active layer of the resonator wafer; masking the single crystal silicon semiconductor material active layer of the resonator wafer with photoresist material; a single crystal silicon resonator is machined in the active layer of the resonator wafer using silicon dry etch micromachining technology; and the photoresist material is subsequently dry stripped.

Claims

1. :

A method for forming a vibrating micromechanical structure, the method comprising;

in a base substrate, forming one or more resonator anchors adjacent to a capacitive air gap;

to the resonator anchors of the base substrate, coupling a single crystal silicon semiconductor material active layer of a Silicon-On-Insulator resonator wafer having a dielectric layer between a semiconductor material handle layer and the semiconductor material active layer;

removing the handle and dielectric layers of the Silicon-On-Insulator resonator wafer; and

in the single crystal silicon semiconductor material active layer of the Silicon-On-Insulator resonator wafer, silicon dry etch machining a single crystal silicon resonator.

2. :

The method of claim 1 wherein the base substrate further comprises a Silicon-On-Insulator base wafer; and

coupling the active layer of the Silicon-On-Insulator resonator wafer to the active layer of the Silicon-On-Insulator base wafer further comprises a bonding method selected from the group of bonding methods consisting of direct bonding, fusion bonding, frit bonding, and low temperature bonding processes of the same.

3. :

The method of claim 1 wherein the base substrate further comprises an insulating wafer; and

coupling the active layer of the Silicon-On-Insulator resonator wafer to the resonator anchors of the base substrate further comprises a bonding method selected from the group of bonding methods consisting of anodic bonding, eutectic bonding, thermal compression bonding, adhesive bonding, and low temperature bonding processes of the same.

4. :

The method of claim 3 wherein forming the capacitive air gap and one or more resonator anchors further comprises a combination of bulk and surface micromachining and metal deposition and etching.

5. :

The method of claim 1 wherein silicon dry etch machining a single crystal silicon resonator in the single crystal silicon semiconductor material active layer of the second Silicon-On-Insulator wafer further comprises one of reactive ion etching and deep reactive ion etching.

6. :

The method of claim 1 wherein silicon dry etch machining a single crystal silicon resonator in the single crystal silicon semiconductor material active layer of the Silicon-On-Insulator resonator wafer further comprises masking with photoresist material and subsequent dry stripping the photoresist material.

7. :

The method of claim 1, further comprising;

in the base substrate, forming one or more alignment marks; and

in the active layer of the Silicon-On-Insulator resonator wafer, forming one or more windows for alignment with the one or more alignment marks in the base substrate.

8. :

The method of claim 1 wherein silicon dry etch machining a single crystal silicon resonator in the single crystal silicon semiconductor material active layer of the Silicon-On-Insulator resonator wafer further comprises aligning using a double sided aligner.

9. :

The method of claim 1 wherein silicon dry etch machining a single crystal silicon resonator in the single crystal silicon semiconductor material active layer of the Silicon-On-Insulator resonator wafer further comprises machining a single crystal silicon resonator configured as one of a clamped-clamped resonator beam, a clamped-free resonator beam, a free-free resonator beam, a single crystal silicon membrane, and a single crystal silicon disk.

10. :

The method of claim 9, further comprising machining one or more transmission lines in the base substrate; and

wherein machining a single crystal silicon resonator further comprises machining a single crystal silicon resonator that is structured to form a filter device.

11. :

A method for forming a vibrating micromechanical structure, the method comprising;

micromachining one or more resonator structure anchors, a capacitive air gap, one or more isolation trenches, and one or more alignment marks in a single crystal silicon semiconductor material active layer of a first Silicon-On-Insulator wafer having a dielectric layer between a semiconductor material handle layer and the semiconductor material active layer;

fusion bonding a single crystal silicon semiconductor material active layer of a second Silicon-On-Insulator wafer directly to the active layer of the first Silicon-On-Insulator wafer, the second Silicon-On-Insulator wafer having a dielectric oxide layer between a semiconductor material handle layer and the semiconductor material active layer;

removing the handle and dielectric oxide layers of the second Silicon-On-Insulator wafer;

etching one or more windows in the active layer of the second Silicon-On-Insulator wafer; and

silicon dry etch micromachining a single crystal silicon resonator structure in the single crystal silicon semiconductor material active layer of the second Silicon-On-Insulator wafer.

12. :

The method of claim 11 wherein silicon dry etch micromachining a single crystal silicon resonator structure in the single crystal silicon semiconductor material active layer of the second Silicon-On-Insulator wafer further comprises aligning a mask relative to the one or more alignment marks in the active layer of the first Silicon-On-Insulator wafer.

13. :

The method of claim 11 wherein silicon dry etch micromachining a single crystal silicon resonator structure in the single crystal silicon semiconductor material active layer of the second Silicon-On-Insulator wafer further comprises micromachining the single crystal silicon resonator structure using one of reactive ion etching and deep reactive ion etching.

14. :

The method of claim 13 wherein micromachining the single crystal silicon resonator structure further comprises initially masking the single crystal silicon semiconductor material active layer of the second Silicon-On-Insulator wafer with photoresist material and subsequently dry stripping the photoresist material.

15. :

The method of claim 11 wherein micromachining one or more resonator structure anchors, a capacitive air gap, one or more isolation trenches, and one or more alignment marks in a single crystal silicon semiconductor material active layer of a first Silicon-On-Insulator wafer further comprises micromachining using a conventional photolithography masking and wet etching micromachining method.

16. :

The method of claim 11 wherein silicon dry etch machining a single crystal silicon resonator structure in the single crystal silicon semiconductor material active layer of the second Silicon-On-Insulator wafer further comprises machining a single crystal silicon resonator structured as one of a clamped-clamped resonator beam, a clamped-free resonator beam, a free-free resonator beam, a single crystal silicon membrane, and a single crystal silicon disk.

17. :

The method of claim 16, further comprising micromachining one or more RF transmission lines in the active layer of the first Silicon-On-Insulator wafer; and

wherein machining a single crystal silicon resonator structure further comprises machining a single crystal silicon resonator structure that is structured to form a filter device.

18. :

A method for forming a filter device, the method comprising;

a base wafer being one of an insulating wafer and a Silicon-On-Insulator wafer;

a resonator wafer being a Silicon-On-Insulator wafer having a single crystal silicon semiconductor material active layer and a semiconductor material handle layer separated by a dielectric layer;

in the base wafer, forming one or more resonator anchors adjacent to a capacitive air gap and one or more RF transmission lines;

coupling the active layer of the Silicon-On-Insulator resonator wafer directly to the resonator anchors of the base wafer;

removing the handle and dielectric layers of the Silicon-On-Insulator resonator wafer; and

in the single crystal silicon semiconductor material active layer of the Silicon-On-Insulator resonator wafer, silicon dry etch micromachining a single crystal silicon resonator.

19. :

The method of claim 18 wherein the base wafer further comprises Silicon-On-Insulator wafer having a single crystal silicon semiconductor material active layer and a semiconductor material handle layer separated by a dielectric layer; and

forming one or more resonator anchors adjacent to a capacitive air gap and one or more RF transmission lines further comprises forming the one or more resonator anchors, the capacitive air gap and the one or more RF transmission lines in the active layer of the Silicon-On-Insulator base wafer.

20. :

The method of claim 19 wherein coupling the active layer of the Silicon-On-Insulator resonator wafer to the active layer of the Silicon-On-Insulator base wafer further comprises fusing the different active layers of the Silicon-On-Insulator resonator and base wafers into a single integrated active layer of single crystal silicon material by fusion bonding.