Semiconductor device with shielding

• US 7,096,732 B2
• Filed: 12/20/2001
• Issued: 08/29/2006
• Est. Priority Date: 12/20/2000
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Higuchi, Hirofumi, Katsumata, Takashi
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Hanley, John C
• Application Number:
  US10/022,224
• Publication Number:
  US 20020073780A1
• Time in Patent Office: 1,713 Days
• Field of Search: 735/041.2, 735/041.4, 735/143.2, 257414-420
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

A semiconductor device includes gaps formed in a semiconductor substrate to provide an inner portion movable in x and y directions. Drive electrodes vibrate the inner portion in the x direction, and detection electrodes detect movement in the y direction generated when an angular velocity is applied thereto. Monitor electrodes generate monitor signals for monitoring movement of the inner portion in the x direction. Shield wires are provided between the drive and detection electrodes and the monitor electrodes to suppress capacitive coupling. Dummy electrodes adjacent to the output electrodes and capacitively coupled to the drive electrodes generate a dummy signal. Dummy signal wires are respectively connected to the dummy electrodes and to the circuit substrate. The dummy signal includes an induced component of a periodical signal and is supplied to the circuit substrate to cancel another induced component of the periodical signal in the drive and monitor signals.

Claims

1. A semi conductor device, comprising:

a circuit substrate;

a conductive substrate;

an insulation film disposed on said conductive substrate;

a semiconductor substrate including

a movable portion that may be vibrated in a first direction;

an input electrode disposed on said insulation film so as to face said movable portion through an open space, receiving periodic signal from said circuit substrate, and causing said movable portion to vibrate in said first direction, a first stray capacitor of a first capacitance being induced in said insulating film between said input electrode and said conductive substrate;

an output electrode disposed on said insulation film so as to face said movable portion through an open space, and outputting vibration signal indicating vibration of said movable portion in a second direction, a second stray capacitor of a second capacitance being induced in said insulating film between said out electrode and said conductive substrate, a noise derived from the periodical signal being added to the vibration signal based on the first and second stray capacitors;

a dummy electrode disposed on said insulation film so as to induce a third stray capacitor of a third capacitance in said insulating film between said dummy electrode and said conductive substrate in a manner that the third capacitance is substantially equal to the second capacitance induced by the output electrode, a dummy signal being generated in said dummy electrode from the periodical signal received in said input electrode based on the first and third stray capacitors; and

a noise reducer which reduces the noise in the vibration signal by using the dummy signal of said dummy electrode.

2. The semiconductor device as claimed in claim 1, wherein a top surface of said semiconductor substrate has a rectangular shape, and said input electrode and said output electrode are arranged at locations corresponding to different sides of said rectangular shape, respectively.

3. The semiconductor device as claimed in claim 1, further comprising:

an input which connects said input electrode and said circuit substrate to supply the periodic signal to said input electrode;

an output wire which connects said output electrode and said circuit substrate to supply the vibration signal to said circuit substrate; and

a shield wire which is disposed between said input wire and said output wire and is set at a constant potential to provide capacitive shielding between said input wire and said output wire.

4. The semiconductor device as claimed in claim 3, wherein said shield wire is grounded at said circuit substrate.

5. The semiconductor device as claimed in claim 3, wherein said shield wire is arranged adjacent to either of said input electrode or said output electrode.

6. The semiconductor device as claimed in claim 3, wherein said shield wire is arranged adjacent to either of said input wire or said output wire.

7. The semiconductor device as claimed in claim 1, wherein said movable portion is movable in a second direction perpendicular to said first direction, said semiconductor device further comprising angular velocity detection means for detecting vibration of said movable portion in said second direction to determine an angular velocity around an axis perpendicular to said first direction and second direction to generate said detection signal.

8. The semiconductor device as claimed in claim 1, wherein the noise reducer has a subtractor which subtracts a value of the dummy signal generated in the dummy electrode from a value of the vibration signal outputted from the output electrode and outputs a difference signal indicating a difference between the vibration signal and the dummy signal.

9. The semiconductor device as claimed in claim 8, wherein said shield wire is grounded at said circuit substrate.

10. The semiconductor device as claimed in claim 1, wherein said movable portion comprises an electrode facing said output electrode to provide a capacitance providing capacitive variation when said movable portion vibrates in said second direction.

11. A semiconductor device, comprising:

a circuit substrate;

a conductive substrate;

an insulation film disposed on said conductive substrate;

a semiconductor substrate including

a movable portion capable of vibrating in a first direction and vibrating in a second direction perpendicular to the first direction when an angular velocity around a third direction perpendicular to the first and second directions is applied to the movable portion;

a drive electrode disposed on said insulation film so as to face said movable portion through an open space, receiving a periodic signal from said circuit substrate, and causing said movable portion to vibrate in the first direction, a first stray capacitor of a first capacitance being induced in said insulating film between said drive electrode and said conductive substrate;

a detection electrode which is disposed on said insulation film so as to face said movable portion through an open space, and generates a detection signal indicating vibration of said movable portion in said second direction, a second stray capacitor of a second capacitance being induced in said insulating film between said detection electrode and said conductive substrate, a noise derived from the periodic signal being added to the detection signal based on the first and second stray capacitors;

a monitor electrode which is disposed on said insulation film so as to face said movable portion through an open space, and generates a monitor signal indicating vibration of said movable portion in said first direction, a third stay capacitor of the second capacitance being induced in said insulating film between said monitor electrode and said conductive substrate, a noise derived from the periodic signal being added to the monitor signal based on the first and third stray capacitors;

a dummy electrode disposed on said insulation film so as to induce a fourth stray capacitor of a third capacitance in said insulating film between said dummy electrode and said conductive substrate in a manner that the third capacitance is substantially equal to the second capacitance, a dummy signal being generated in said dummy electrode from the periodic signal received in said input electrode based on the first and fourth stray capacitors; and

a noise reducer which reduces the noise of the detection signal or the monitor signal by using the dummy signal of said dummy electrode.

12. The semiconductor device as claimed in claim 11, wherein said semiconductor substrate is a rectangular plate, and said drive electrode and a group of said detection and monitor electrodes are arranged at locations corresponding to different sides of said rectangular plate, respectively.

13. The semiconductor device as claimed in claim 11, further comprising:

a drive wire which connects said drive electrode and said circuit substrate to supply the periodic signal to said drive electrode;

a detection wire which connects said detection electrode and said circuit substrate to supply the detection signal to said circuit substrate;

a monitor wire which connects said monitor electrode and said circuit substrate to supply the monitor signal to said circuit substrate; and

a shield wire which is disposed between said drive wire and a group of said detection and monitor wires and is set at a constant potential to provide capacitive shielding between said drive wire and the group of said detection and monitor wires.

14. The semiconductor device as claimed in claim 13, wherein said shield wire is arranged adjacent to either said drive wire or both said detection wire and said monitor wire.

15. The semiconductor device as claimed in claim 11, wherein the noise reducer has a subtractor which subtracts a value of the dummy signal generated in the dummy electrode from a value of the detection or monitor signal outputted from the detection or monitor electrode and outputs a difference signal indicating a difference between the detection or monitor signal and the dummy signal.

17. The semiconductor device as claimed in claim 11, wherein said movable portion comprises an electrode facing said detection electrode to provide a capacitance providing capacitive variation when said movable portion vibrates in said second direction.

16. The semiconductor device as claimed 11, wherein said movable portion comprises an electrode facing said monitor electrode to provide a capacitance providing capacitive variation when said movable portion vibrates in said first direction.