Semiconductor mechanical sensor

• US 7,685,877 B2
• Filed: 06/30/2008
• Issued: 03/30/2010
• Est. Priority Date: 08/21/1992
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Fujii, Tetsuo, Imai, Masahito
• Primary Examiner(s): Kwok; Helen C.
• Application Number:
  US12/215,884
• Publication Number:
  US 20090014820A1
• Time in Patent Office: 638 Days
• Field of Search: 7350412-50415, 735/040.4, 735/143.2, 735/142.9, 735/141.6, 361/283.3, 361/321.1, 361/283.1, 257415-419, 438 50- 52
• US Class Current: 73/514.32
• 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 semiconductor mechanical quantity sensor comprising:

a first layer formed by a silicon substrate;

a second layer formed by an insulation layer disposed on said first layer;

a third layer formed by a silicon layer disposed on said second layer;

a fourth layer formed by an insulation layer disposed on said third layer; and

a fifth layer formed by a silicon layer disposed on said fourth layer;

wherein

the thickness of the fifth layer is greater than the thickness of the third layer,

said fifth layer is provided with a weight being movable due to the effect of the mechanical quantity, a movable electrode being included in said weight, a fixed electrode facing said movable electrode, and an electric routing path being separated from said weight and extending in a direction perpendicular to said first layer;

said third layer is formed by a polysilicon layer containing high density impurities and extending in a direction parallel with said first layer,

said polysilicon layer and said electric routing path are electrically connected via a bottom contact for an electric connection, the bottom contact being formed below the electric routing path and between said third layer and said fifth layer.

2. A semiconductor mechanical quantity sensor as set forth in claim 1, wherein said fifth layer is provided with a plurality of metal layer patterns formed on a major surface of the fifth layer and arranged on substantially the same surface.

3. A semiconductor mechanical quantity sensor as set forth in claim 1, wherein said fifth layer and said third layer having the same conductivity type.

4. A semiconductor mechanical quantity sensor as set forth in claim 2, wherein said plurality of metal layer patters are made of an aluminum layer.

5. A semiconductor mechanical quantity sensor comprising:

a silicon layer formed on a substrate via an insulation layer;

a movable portion formed on said silicon layer and having a first surface and a second surface orthogonal to each other;

a first correspondent electrode formed by a polysilicon layer which is insulated and separated from said substrate and is arranged in parallel with the major surface of said silicon layer, said polysilicon layer being opposed to the first surface of said movable portion; and

a second correspondent electrode which is insulated and separated from said substrate and which is opposed to the second surface of the movable portion,

said silicon layer and said first correspondent electrode formed by a polysilicon layer having the same conductivity type, and said second correspondent electrode being formed using said silicon layer, said second correspondent electrode being insulated and separated from said substrate, wherein

at least one electric routing path is formed using said silicon layer, the at least one electric routing path extending from said first correspondent electrode to an external contacting electrode which is formed on a surface of the silicon layer.

6. A semiconductor mechanical quantity sensor as set forth in claim 5, wherein said electric routing paths are insulated by an insulator including a trench.

7. A semiconductor mechanical quantity sensor as set forth in claim 5, wherein said electric routing paths are insulated and separated from the movable portion.

8. A semiconductor mechanical quantity sensor as set forth in claim 5, wherein one of said first and second correspondent electrodes forms a vibration electrode for exciting said movable portion and the other correspondent electrode forms a detection electrode for detecting the displacement of the movable portion.

9. A semiconductor mechanical quantity sensor as set forth in claim 8, further comprising a sensing electrode for detecting the vibration of said movable portion, said sensing electrode and said excitation electrode being parallel with the opposing surface of the movable portion corresponding to said vibration electrode.

10. A semiconductor mechanical quantity sensor as set forth in claim 8, wherein said substrate itself forms said vibration electrode.

11. A semiconductor mechanical quantity sensor as set forth in claim 5, wherein an opposing member is provided on the side of said movable portion opposite to the side thereof facing to said substrate and is spaced from the movable portion at a predetermined distance.

12. A semiconductor mechanical quantity sensor as set forth in claim 11, wherein said opposing member increases the sensor output and prevents the breakage of said movable portion.

13. A semiconductor mechanical quantity sensor as set forth in claim 5, wherein a silicon nitride is formed on the surface of said silicon layer.

14. A semiconductor mechanical quantity sensor comprising:

a first layer formed by a silicon substrate;

a second layer formed by an insulation layer disposed on said first layer;

a third layer formed by a silicon layer disposed on said second layer;

a fourth layer formed by an insulation layer disposed on said third layer; and

a fifth layer formed by a silicon layer disposed on said fourth layer;

wherein

the thickness of said fifth layer is greater than the thickness of said third layer,

said fifth layer and said third layer have the same conductivity type,

said fifth layer is provided with a weight being movable due to the effect of the mechanical quantity and a movable electrode included in said weight,

said third layer is formed by a polysilicon layer containing high density impurities and extending in a direction parallel with said first layer,

said polysilicon layer and a part of said fifth layer are electrically connected via a bottom contact for an electric connection, said bottom contact being formed below the fifth layer,

a predetermined aluminum layer is formed on the major surface of said fifth layer and arranged on substantially the same surface.

15. A semiconductor mechanical quantity sensor as set forth in claim 14, wherein said fifth layer is provided with fixed electrodes facing said movable electrode.

16. A semiconductor mechanical quantity sensor as set forth in claim 14, wherein said third layer includes a shield layer of polysilicon.

17. A semiconductor mechanical quantity sensor as set forth in claim 14, wherein said predetermined aluminum layer is a wiring layer.