Process for producing a speed of rotation coriolis sensor

• US 6,214,243 B1
• Filed: 10/20/1998
• Issued: 04/10/2001
• Est. Priority Date: 10/20/1995
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Offenberg, Michael, Lutz, Markus, Laermer, Franz, Schilp, Andrea, Muenzel, Horst
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): OLSEN, ALLAN W
• Application Number:
  US09/051,878
• Time in Patent Office: 903 Days
• Field of Search: 216/2, 216/57, 216/67, 216/72, 216/79, 216/99, 738/626.26, 735/044, 732/042.65, 735/041.2, 735/041.6, 735/043.2, 735/143.5, 737/77, 361/283.3, 361/280, 205/561, 205/565, 205/99
• US Class Current: 216/2
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2203/058 Rotation out of a plane parallel to the substrate
• CPC Class Codes: B81B 3/0051 For defining the movement, i.e. structures that guide or limit the movement of an element mechanical arrangements for preventing or damping vibration or shock H01H3/60
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01C 19/5769 Manufacturing; Mounting; Housings

Abstract

A process for the manufacture of a Coriolis rate-of-rotation sensor with oscillatory support masses spring-suspended on a substrate as well as driving means for the excitation of the planar oscillation of the oscillating masses and evaluation means for the determination of a Coriolis acceleration. Oscillating masses, driving means and integrated stops are structured in a common operation by means of plasma etching from a silicon-on-insulator (SOI) wafer.

Claims

1. A process for manufacturing a rate-of-rotation sensor including a substrate structure, the substrate structure including deflectable resonator masses and springs, the deflectable resonator masses situating an evaluation arrangement for detecting Coriolis accelerations, and a driving arrangement for exciting a planar vibration of the deflectable resonator masses, the deflectable resonator masses being resiliently suspended on a substrate, the process comprising the steps of:

a) in a single sequence operation, plasma-etching the substrate structure and a driving arrangement into a top side of a silicon-on-insulator (SOI) wafer, the SOI wafer including a buried oxide layer;

b) wet-etching an opening through a bulk substrate and underneath the substrate structure and the driving arrangement, the bulk substrate forming a rear side of the SOI wafer; and

c) removing the buried oxide layer underneath the substrate structure and the driving arrangement.

2. The process according to claim 1, wherein the buried oxide layer includes an etching stop for the plasma etching procedure at the top side and at the rear side of the SOI wafer.

3. The process according to claim 1, wherein the buried oxide layer includes an etching stop for the plasma-etching step, the plasma etching step further including a substep of producing an SOI membrane layer within the SOI wafer from the rear side of the SOI wafer.

4. The process according to claim 3, further comprising the step of:

d) after producing the rate-of-rotation sensor via the front side of the SOI wafer, exposing the SOI membrane layer, the substrate structure and the driving arrangement via the rear side of the SOI wafer using a wet etching procedure.

5. The process according to claim 3, wherein the substrate structure is situated in the SOI membrane layer.

6. The process according to claim 1, further comprising the step of:

e) simultaneously with step a), configuring overload stops for the substrate structure.

7. The process according to claim 6, wherein the substrate structure includes projections situated above the buried oxide layer, and further comprising the steps of:

f) configuring trench-shaped structures around the projections to form the overload stops; and

g) after step f), removing the buried oxide layer as a sacrificial oxide layer.

8. The process according to claim 7, wherein the bulk substrate is situated beneath the projections, and further comprising the step of:

h) via a protected sidewall, isotropically plasma under-etching the bulk substrate to produce clearances, the clearances being produced for increasing a spacing between the projections from a base and for increasing a vertical mobility of the deflectable resonator masses.

9. The process according to claim 7, wherein the protected sidewall includes a teflon-coated sidewall.

10. The process according to claim 7, wherein the bulk substrate is situated beneath the projections, and further comprising the step of:

i) electrochemically etching the bulk substrate to form clearances, the clearances being formed to enlarge clearances for a vertical motion.

11. The process according to claim 1, further comprising the step of:

j) producing top stops and bottom stops for seismic masses.

12. The process according to claim 11, wherein the substrate structure includes projections, and further comprising the step of:

k) configuring bridge-shaped stops over the projections.

13. The process according to claim 12, wherein the bridge-shaped stops include a fixed-resist frame covering an entire structure of the rate-of-rotation sensor.

14. The process according to claim 1, wherein the substrate structure includes at least one projection, and further comprising the step of:

l) applying a cap to the at least one projection, wherein an edge of the cap forms a stop.