Semiconductor mechanical sensor

• US 20050005697A1
• Filed: 07/27/2004
• Published: 01/13/2005
• Est. Priority Date: 08/21/1992
• Status: Active Grant

• Current Assignee: Masahito Imai, Tetsuo Fujii
• Original Assignee: Masahito Imai, Tetsuo Fujii
• Inventors: Fujii, Tetsuo, Imai, Masahito
• Granted Patent: US 6,938,486 B2
• Time in Patent Office: Days
• US Class Current: 73/504.150
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 7/0006 Interconnects
• CPC Class Codes: C07C 303/32 of salts of sulfonic acids
• CPC Class Codes: C07C 303/44 Separation; Purification
• CPC Class Codes: C07C 309/17 containing carboxyl groups bound to the carbon skeleton
• 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: G01C 19/5656 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0817 for pivoting movement of the mass, e.g. in-plane pendulum
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part

Abstract

A semiconductor mechanical sensor having a new structure in which a S/N ratio is improved. In the central portion of a silicon substrate 1, a recess portion 2 is formed which includes a beam structure. A weight is formed at the tip of the beam, and in the bottom surface of the weight in the bottom surface of the recess portion 2 facing the same, an electrode 5 is formed. An alternating current electric power is applied between the weight portion 4 and the electrode 5 so that static electricity is created and the weight is excited by the static electricity. In an axial direction which is perpendicular to the direction of the excitation of the weight, an electrode 6 is disposed to face one surface of the weight and a wall surface of the substrate which faces the same. A change in a capacitance between the facing electrodes is electrically detected, and therefore, a change in a physical force acting in the same direction is detected.

Claims

1. A rotational angular velocity sensor comprising:

a substrate;

a weight being located above said substrate and movably disposed via at least one beam;

a first electrode connected to said weight, wherein the weight, beam and first electrode are formed of common semiconductor material one another;

a second electrode facing said first electrode via insulation to form capacitance between the second and first electrodes, wherein the second electrode is formed of the same semiconductor material as that of the first electrode; and

wherein said first electrode and second electrode are arranged in a first direction and in parallel with the surface of said substrate, the widths of the first and second electrodes extend in a second direction which is in parallel with the surface of the said substrate and perpendicular to said first direction, and

said first electrode is movable in said second direction, the movement of said first electrode induces change in said capacitance, the change thereof corresponds to the rotational angular velocity to be detected.

2. A rotational angular velocity sensor in accordance with claim 1, further comprising a surrounding region being located around said beam, weight, first electrode and second electrode, and insulated from the beam, weight and first electrode, and formed of the same semiconductor material as that of the beam, weight, first electrode and second electrode.

3. A rotational angular velocity sensor in accordance with claim 1, wherein said first electrode and second electrode having metal electrode to be wired externally.

4. A rotational angular velocity sensor in accordance with claim 1, wherein said substrate is comprised of monocrystalline silicon.

5. A rotational angular velocity sensor in accordance with claim 1, wherein said semiconductor material for forming said beam, weight and first electrode and second electrode is silicon.

6. A rotational angular velocity sensor in accordance with claim 1, wherein said semiconductor material for forming each of said beam, weight, first electrode and second electrode having the same conductivity type one another.

7. A rotational angular velocity sensor comprising:

a substrate;

a weight being located above said substrate and movably disposed via at least one beam;

an oscillation unit for oscillating said weight;

a first electrode connected to said weight, wherein the weight, beam and first electrode are formed of common semiconductor material one another;

a second electrode facing said first electrode via insulation to form capacitance between the second and first electrodes, wherein the second electrode is formed of the same semiconductor material as that of the first electrode; and

wherein said first electrode and second electrode are arranged in a first direction and in parallel with the surface of said substrate, the widths of the first and second electrodes extend in a second direction which is in parallel with the surface of said substrate and perpendicular to said first direction, and

said first electrode is movable in said second direction due to the oscillation of said weight by said oscillation unit, the movement of said first electrode induces change in said capacitance, the change thereof corresponds to the rotational angular velocity to be detected.

8. A rotational angular velocity sensor in accordance with claim 7, further comprising a surrounding region being located around said beam, weight, first electrode and second electrode, and insulated from the beam, weight and first electrode, and formed of the same semiconductor material as that of the beam, weight, first electrode and second electrode.

9. A rotational angular velocity sensor in accordance with claim 7, wherein said first electrode and second electrode having metal electrode to be wired externally.

10. A rotational angular velocity sensor in accordance with claim 7, wherein said substrate is comprised of monocrystalline silicon.

11. A rotational angular velocity sensor in accordance with claim 7, wherein said semiconductor material for forming said beam, weight and first electrode and second electrode is silicon.

12. A rotational angular velocity sensor in accordance with claim 7, wherein said semiconductor material for forming each of said beam, weight, first electrode and second electrode having the same conductivity type one another.