Mechanical-quantity measuring device

• US 7,992,448 B2
• Filed: 02/20/2007
• Issued: 08/09/2011
• Est. Priority Date: 03/29/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohta, Hiroyuki, Tanno, Yohei, Shimazu, Hiromi
• Primary Examiner(s): Caputo; Lisa M
• Assistant Examiner(s): ROY, PUNAM P
• Application Number:
  US11/709,075
• Publication Number:
  US 20070228500A1
• Time in Patent Office: 1,631 Days
• Field of Search: 737/27, 737/57, 737/77, 338/2, 338/5, 338/6, 438/48
• US Class Current: 73/777
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 1/2293 of the semi-conductor type semi-conductor devices controllable by variations of applied mechanical force H01L29/84

Abstract

A mechanical-quantity measuring device capable of measuring a strain component in a specific direction with high precision is provided.

At least two or more pairs of bridge circuits are formed inside a semiconductor monocrystal substrate and a semiconductor chip, and one of these bridge circuits forms a n-type diffusion resistor in which a direction of a current flow and measuring variation of a resistor value are in parallel with a <100> direction of the semiconductor monocrystal silicon substrate, and an another bridge circuit is composed of combination of p-type diffusion resistors in parallel with a <110> direction.

Claims

1. A mechanical-quantity measuring device provided with a strain detection unit on a surface of a monocrystalline semiconductor substrate, and using a flat back surface of the monocrystalline semiconductor substrate as an adherence surface so as to be attached to a measured object to measure a strain, the device comprising:

first and second sensors each having a wheatstone bridge formed by a plurality of diffusion resistors;

a first amplifier circuit amplifying a signal outputted by the first sensor; and

a second amplifier circuit amplifying a signal outputted by the second sensor;

wherein;

distances between the plurality of diffusion resistors that form the wheatstone bridge of the first sensor and the plurality of diffusion resistors that form the wheatstone bridge of the second sensor are smaller than a distance between a first transistor of the first amplifier circuit and a second transistor of the second amplifier circuit,

longitudinal directions of the plurality of diffusion resistors of the first sensor have a same direction as longitudinal directions of a plurality of feedback resistors configuring the first amplifier circuit,

longitudinal directions of the plurality of diffusion resistors of the second sensor have a same direction as longitudinal directions of a plurality of feedback resistors configuring the second amplifier circuit, and

the first amplifier circuit of the first sensor and the second amplifier circuit of the second sensor are formed on the monocrystalline semiconductor substrate approximately line-symmetrically with each other.

2. A mechanical-quantity measuring device provided with a strain detection unit on a surface of a monocrystalline semiconductor substrate, and using a flat back surface of the monocrystalline semiconductor substrate as an adherence surface so as to be attached to a measured object to measure a strain, the device comprising:

first and second sensors each having a wheatstone bridge formed by a plurality of diffusion resistors;

a first amplifier circuit amplifying a signal outputted by the first sensor; and

a second amplifier circuit amplifying a signal outputted by the second sensor;

wherein;

distances between the plurality of diffusion resistors that form the wheatstone bridge of the first sensor and the plurality of diffusion resistors that form the wheatstone bridge of the second sensor are smaller than a distance between a first transistor of the first amplifier circuit and a second transistor of the second amplifier circuit,

longitudinal directions of a plurality of feedback resistors configuring the first amplifier circuit have a same direction, and longitudinal directions of a plurality of feedback resistors configuring the second amplifier circuit have a same direction,

longitudinal directions of the plurality of diffusion resistors of the first sensor are orthogonal to longitudinal directions of the plurality of diffusion resistors of the second sensor, and centers of the plurality of diffusion resistors of the first sensor are brought into a line, and centers of the plurality of diffusion resistors of the second sensor are brought into a line, and

the first amplifier circuit of the first sensor and the second amplifier circuit of the second sensor are formed on the monocrystalline semiconductor substrate approximately line-symmetrically with each other.