Method and structure for forming a gyroscope and accelerometer

• US 8,530,259 B2
• Filed: 05/24/2012
• Issued: 09/10/2013
• Est. Priority Date: 01/03/2005
• Status: Expired due to Fees

• Current Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Original Assignee: Miradia Inc. (Walsin Lihwa Corporation)
• Inventors: Chen, Dongmin, Payne, Justin, Tseng, Li-Tien
• Primary Examiner(s): Luu, Chuong A
• Assistant Examiner(s): Doan, Nga
• Application Number:
  US13/480,351
• Publication Number:
  US 20120228727A1
• Time in Patent Office: 474 Days
• Field of Search: 438 50- 54, 257/417, 257/E29.324, 257/E21.002
• US Class Current: 438/50
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81C 1/00238 Joining a substrate with an electronic processing unit and a substrate with a micromechanical structure
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration

Abstract

A method for fabricating a micro electromechanical device includes providing a first substrate including control circuitry. The first substrate has a top surface and a bottom surface. The method also includes forming an insulating layer on the top surface of the first substrate, removing a first portion of the insulating layer so as to form a plurality of standoff structures, and bonding a second substrate to the first substrate. The method further includes thinning the second substrate to a predetermined thickness and forming a plurality of trenches in the second substrate. Each of the plurality of trenches extends to the top surface of the first substrate. Moreover, the method includes filling at least a portion of each of the plurality of trenches with a conductive material, forming the micro electromechanical device in the second substrate, and bonding a third substrate to the second substrate.

Claims

1. A method of fabricating a device, the method comprising:

providing a CMOS substrate having one or more electrodes and control circuitry formed in proximity to a first surface;

forming a first photosensitive layer over the first surface of the CMOS substrate;

patterning and etching the first photosensitive layer to form a first trench, the first trench extending to a first electrode from among the one or more electrodes;

removing a remaining portion of the first photosensitive layer;

forming a second photosensitive layer over the first substrate, wherein a portion of the second photosensitive layer overlays the first trench;

etching the second photosensitive layer and a portion of the CMOS substrate to define a plurality of standoff structures;

attaching a second substrate to the CMOS substrate, the second substrate having an upper surface and a lower surface;

thinning the second substrate to a predetermined thickness;

forming a third photosensitive layer over the upper surface of the second substrate;

etching the third photosensitive layer and a portion of the second substrate to define a second trench;

the second trench being aligned with the first trench, wherein the second trench merges with the first trench to form a continuous trench extending from the upper surface of the second substrate to the first electrode;

forming a conformal adhesion layer over the upper surface of the second substrate and over sidewalls of the continuous trench;

forming a conformal barrier layer over the adhesion layer;

filling the continuous trench with a conductive material;

forming a passivation layer over the barrier layer; and

patterning and etching a portion of the second substrate to form a micro-electromechanical device.

2. The method of claim 1 wherein the first photosensitive layer comprises a photoresist layer.

3. The method of claim 1 wherein thinning of the second substrate comprises performing a CMP process.

4. The method of claim 1 wherein thinning of the second substrate comprises performing an RIE process.

5. The method of claim 1 wherein the micro-electromechanical device comprises an accelerometer.

6. The method of claim 5 wherein the accelerometer comprises a proof mass, stator comb fingers, and moveable comb fingers.

7. The method of claim 1 further comprising:

bonding a cap wafer to a portion of the second substrate to form a packaged structure; and

dicing the packaged structure to form individual dies.

8. The method of claim 7 wherein the individual dies include a plurality of accelerometers.

9. A method comprising:

providing a first substrate having one or more electrodes and control circuitry formed in proximity to a first surface;

forming a first photosensitive layer over the first surface of the first substrate;

patterning and etching the first photosensitive layer to form a first trench, the first trench extending to a first electrode from among the one or more electrodes;

forming a second photosensitive layer over the first substrate, wherein a portion of the second photosensitive layer overlays the first trench;

etching the second photosensitive layer and a portion of the first substrate to define a plurality of standoff structures;

attaching a second substrate to the first substrate, the second substrate having an upper surface and a lower surface;

thinning the second substrate to a predetermined thickness;

forming a third photosensitive layer over the upper surface of the second substrate;

etching the third photosensitive layer and a portion of the second substrate to define a second trench;

the second trench being aligned with the first trench, wherein the second trench merges with the first trench to form a continuous trench extending from the upper surface of the second substrate to the first electrode;

forming an adhesion layer over the upper surface of the second substrate and over sidewalls of the continuous trench;

forming a barrier layer over the adhesion layer;

filling the continuous trench with a conductive material; and

patterning and etching a portion of the second substrate to form a micro-electromechanical device.

10. The method of claim 9 wherein the first substrate is a CMOS substrate.

11. The method of claim 9 further comprising forming a passivation layer over the barrier layer prior to the patterning and etching.

12. The method of claim 9 wherein the conductive material comprises one of Titanium, Titanium Nitride (TiN) or Tungsten (W).

13. The method of claim 9 wherein the micro-electromechanical device comprises a gyroscope.