Electromechanical device including a suspended structure and method of fabricating the same

• US 9,650,237 B2
• Filed: 04/17/2014
• Issued: 05/16/2017
• Est. Priority Date: 04/19/2013
• Status: Active Grant

• Current Assignee: Agency For Science Technology and Research
• Original Assignee: Agency For Science Technology and Research
• Inventors: Singh, Navab, Ocak, Ilker E., Tsai, Julius Ming Lin
• Primary Examiner(s): NGUYEN, DUY T V
• Application Number:
  US14/778,514
• Publication Number:
  US 20160289063A1
• Time in Patent Office: 1,125 Days
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2201/0271 Resonators; ultrasonic resonators
• CPC Class Codes: B81B 2201/0292 Sensors not provided for in B81B2201/0207 - B81B2201/0285
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 7/0048 between the MEMS die and the substrate
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/0172 Seals
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends
• CPC Class Codes: G01R 33/00 Arrangements or instruments for measuring magnetic variables
• CPC Class Codes: G01R 33/0052 Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips devices based on galvano-magnetic effect or the like H10N50/85
• CPC Class Codes: G01R 33/0286 comprising microelectromechanical systems [MEMS] MEMS devices in general B81B
• CPC Class Codes: H01L 25/00 Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereofdevices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00; photovoltaic modules or arrays of photovoltaic cells H01L31/042 ; panels or arrays of photo electrochemical cells H01G9/2068
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

An electromechanical device and method of fabrication thereof comprising: providing a first wafer with a circuit arrangement on a first surface thereof and a first electrode on a second surface thereof; forming first and second via structures from the first surface to the second surface of the first wafer, said first via electrically connecting the first electrode with the circuit arrangement; providing a second wafer with a suspended structure on a first surface thereof; forming a second electrode on the suspended structure; forming an interconnect structure on the first surface of the second wafer that electrically connects with the second electrode; bonding the first wafer to the second wafer with the second surface of the first wafer facing the first surface of the second wafer, with the second via structure electrically connecting the circuit arrangement to the interconnect structure, and the first and second electrodes forming a capacitive structure.

Claims

1. A method of fabricating an electromechanical device, the method comprising:

providing a first wafer;

forming a circuit arrangement on a first surface of the first wafer;

forming a first electrode on a second surface of the first wafer;

forming a first via structure from the first surface of the first wafer to the second surface of the first wafer, the first via structure electrically connecting the first electrode with the circuit arrangement;

forming a second via structure from the first surface of the first wafer to the second surface of the first wafer, the second via structure electrically connecting the circuit arrangement;

providing a second wafer;

forming a suspended structure on a first surface of the second wafer with a spacing formed between the suspended structure and a second surface of the second wafer;

forming a second electrode on the suspended structure;

forming an interconnect structure on the first surface of the second wafer, the interconnect structure electrically connecting the second electrode; and

bonding the first wafer to the second wafer with the second surface of the first wafer facing the first surface of the second wafer, the second via structure electrically connecting the interconnect structure, and the first electrode and the second electrode forming a capacitive structure.

2. The method according to claim 1, further comprising:

forming a sealing structure between the first wafer and the second wafer.

3. The method according to claim 1, further comprising:

forming a coil structure on the first surface of the second wafer.

4. The method according to claim 3, wherein forming the coil structure comprises:

forming a first metal layer; and

forming a conductive via on the first metal layer and forming a second metal layer on the conductive via.

5. The method according to claim 3, further comprising:

attaching the first wafer to a transfer wafer with the first surface of the first wafer facing the transfer wafer; and

removing a portion of the first wafer to form the second surface of the first wafer.

6. The method according to claim 1, further comprising:

forming a third via structure from the first surface of the first wafer to the second surface of the first wafer;

forming a multi-layer metal structure on the first surface of the second wafer; and

bonding the first wafer to the second wafer with the third via structure electrically connecting the multilayer metal structure.

7. The method according to claim 1,

wherein the suspended structure, the first electrode on the second surface of the first wafer and the second electrode on the suspended structure form any one of a lateral axis magnetometer, a differential vertical axis accelerometer, a single ended vertical axis accelerometer and a see-saw resonator.

8. The method according to claim 1, further comprising:

forming a cavity on the second surface of the first wafer; and

depositing getter material within the cavity.

9. The method according to claim 8, further comprising:

bonding the first wafer to the second wafer to vacuum-seal the cavity.

10. The method according to claim 9, further comprising:

forming a further suspended structure on the first surface of the second wafer with a further spacing formed between the further suspended structure and the second surface of the second wafer.

11. An electromechanical device comprising:

a first wafer having a first surface and a second surface opposite the first surface;

a circuit arrangement on the first surface of the first wafer;

a first electrode on the second surface of the first wafer;

a first via structure extending from the first surface of the first wafer to the second surface of the first wafer, the first via structure electrically connecting the first electrode with the circuit arrangement;

a second via structure extending from the first surface of the first wafer to the second surface of the first wafer, the second via structure electrically connecting with the circuit arrangement;

a second wafer bonded to the first wafer, the second wafer having a first surface and a second surface opposite the first surface;

a suspended structure on the first surface of the second wafer with a spacing between the suspended structure and the second surface of the second wafer;

a second electrode on the suspended structure; and

an interconnect structure on the first surface of the second wafer, the interconnect structure electrically connecting the second electrode;

wherein the first wafer is bonded to the second wafer with the second surface of the first wafer facing the first surface of the second wafer, the second via structure electrically connecting the interconnect structure and the first electrode and the second electrode forming a capacitive structure.

12. The electromechanical device according to claim 11, further comprising:

a sealing structure between the first wafer and the second wafer.

13. The electromechanical device according to claim 11, further comprising:

a coil structure on the first surface of the second wafer.

14. The electromechanical device according to claim 13, wherein the coil structure comprises:

a first metal layer; and

a conductive via on the first metal layer and a second metal layer on the conductive via.

15. The electromechanical device according to claim 11, further comprising:

a third via structure extending from the first surface of the first wafer to the second surface of the first wafer;

a multi-layer metal structure on the first surface of the second wafer; and

wherein the first wafer is bonded to the second wafer with the third via structure electrically connecting the multi-layer metal structure.

16. The electromechanical device according to claim 11,

wherein the suspended structure, the first electrode on the second surface of the first wafer and the second electrode on the suspended structure form any one of a lateral axis magnetometer, a differential vertical axis accelerometer, a single ended vertical axis accelerometer and a see-saw resonator.

17. The electromechanical device according to claim 11, further comprising:

a cavity on the second surface of the first wafer; and

getter material within the cavity.

18. The electromechanical device according to claim 17,

wherein the cavity is a vacuum-sealed cavity.

19. The method according to claim 18, further comprising:

a further suspended structure on the first surface of the second wafer within the vacuum-sealed cavity with a further spacing formed between the further suspended structure and the second surface of the second wafer.

20. The electromechanical device according to claim 19,

wherein the further suspended structure is any one of a vertical axis magnetometer, a lateral axis magnetometer, a differential vertical axis accelerometer, single ended vertical axis accelerometer, a lateral axis accelerometer, a fully differential lateral axis accelerometer, a vertical axis gyroscope, a lateral resonator and a see-saw resonator.