Semiconductor mechanical sensor

• US 7,040,165 B2
• Filed: 02/22/2005
• Issued: 05/09/2006
• 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:
  US11/062,935
• Publication Number:
  US 20050132800A1
• Time in Patent Office: 441 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, 438 50- 52, 257415-419
• 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;

said third layer is formed by a polysilicon layer being doped with high density impurities and configured with a predetermined pattern in a direction parallel with said first layer,

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

said polysilicon layer and said electric routing paths are electrically connected via a bottom contact for an electric connection, the bottom contact being formed at a predetermined position on said fourth layer while passing through the fourth layer.

2. A semiconductor mechanical quantity sensor as set forth in claim 1, wherein said fifth layer is provided with a plurality of wiring layers each made of metal being formed on a major surface of the fifth layer and arranged on substantially the same surface, whereby one of said wiring layers is connected with said electric routing paths.