Method of fabricating a sensor

• US 6,296,779 B1
• Filed: 02/22/1999
• Issued: 10/02/2001
• Est. Priority Date: 05/31/1996
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Clark, William A., Juneau, Thor, Howe, Roger T.
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): Ahmed, Shamim
• Application Number:
  US09/255,236
• Time in Patent Office: 953 Days
• Field of Search: 216/66, 216/2, 438/14, 73/504.16
• US Class Current: 216/66
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

A microfabricated gyroscope to measure rotation about an axis parallel to the surface of the substrate. A voltage differential may be applied between pairs of electrode fingers to reduce the quadrature error. A microfabricated gyroscope includes a vibratory structure and interdigited electrodes having a high aspect ratio.

Claims

1. A method of fabricating a sensor, comprising:

forming an insulative layer on a first substrate;

forming a patterned conductive layer on the insulative layer;

forming a recess in a first surface of a second substrate;

bonding the first surface of the second substrate to the patterned conductive layer of the first substrate so that the recess defines an enclosed cavity between the first and second substrates;

forming a circuitry for the sensor on a second surface of the second substrate; and

etching a plurality of trenches in the second substrate from the second surface of the cavity, the plurality of trenches defining a vibratory structure formed of the second substrate and conneted to the first substrate by the patterned conductive layer.

2. The method of claim 1 wherein the vibratory structure has a thickness of at least 25 microns.

3. The method of claim 1 wherein the recess has a depth of about 1 micron.

4. The method of claim 1 wherein the etching step comprises a deep reactive ion etch.

5. The method of claim 1 wherein the patterned conductive layer is polysilicon.

6. The method of claim 5 wherein the insulative layer is an oxide.

7. The method of claim 1 wherein the vibratory structure includes a component surrounded a trench so as to be electrically isolated from a remainder of the second substrate.

8. The method of claim 7 further comprising forming electrical connections to the component through the patterned conductive layer.

9. The method of claim 1 wherein the vibratory structure includes a plurality of components surrounded by trenches so as to be electrically isolated from each other, and the patterned conductive layer is patterned to electrically isolate the plurality of components from each other.

10. The method of claim 1 wherein the first and second substrates are single-crysta silicon.

11. The method of claim 1 wherein the second substrate includes a first side with a first single-crystal silicon layer, a second side with a second single-crystal silicon layer, and an insulator layer separating the first and second single-crystal silicon layers.

12. The method of claim 11 wherein the recess is formed in the first side of the second substrate in the first single-crystal silicon layer.

13. The method of claim 12 further comprising, after the bonding step, thinning the second side of the second substrate on the side of the second single crystal silicon layer until the first single crystal silicon layer is exposed.

14. The method of claim 1 further comprising bonding a capping substrate to the second surface of the second substrate.

15. The method of claim 14 wherein no trenches are formed in the first substrate.

16. A method of fabricating a sensor, comprising:

providing a first substrate;

providing a second substrate having a first single-crystal silicon layer on a first side, a second single-crystal layer on a second side, and an insulator layer between the first and second layer single-crystal silicon layers;

forming a recess in a first surface on the first side of the second substrate;

bonding the first side of the second substrate to the first substrate so that the recess defines an enclosed cavity between the first and second substrates;

thinning the second substrate on the second side until a second surface of the first single-crystal silicon layer is exposed;

forming circuitry for the sensory on the second surface of the second substrate; and

etching a plurality of trenches in the second substrate from the second surface to the cavity, the plurality of trenches defining a vibratory structure formed of the second substrate and connected to the first substrate.