Apparatus for measuring a mechanical quantity

• US 20060043508A1
• Filed: 09/02/2005
• Published: 03/02/2006
• Est. Priority Date: 10/06/2003
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohta, Hiroyuki, Sumigawa, Takashi
• Application Number:
  US11/217,299
• Publication Number:
  US 20060043508A1
• Time in Patent Office: Days
• US Class Current: 257/417
• 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

Abstract

A mechanical quantity measuring apparatus is provided which can make highly precise measurements and is not easily affected by noise even when it is supplied an electricity through electromagnetic induction or microwaves. At least a strain sensor and an amplifier, an analog/digital converter, a rectification/detection/modulation-demodulation circuit, and a communication control circuit are formed in one and the same silicon substrate. Or, the silicon substrate is also formed at its surface with a dummy resistor which has its longitudinal direction set in a particular crystal orientation and which, together with the strain sensor, forms a Wheatstone bridge. With this arrangement, even when a current flowing through the sensor is reduced, measured data is prevented from being buried in noise, allowing the sensor to operate on a small power and to measure a mechanical quantity with high precision even when it is supplied electricity through electromagnetic induction or microwaves.

Claims

1. A mechanical quantity measuring apparatus having formed in one main surface of a single crystal semiconductor substrate:

a strain sensor;

an amplification conversion circuit to amplify a signal from the strain sensor and convert it into a digital signal;

a transmission circuit to transmit the converted digital signal to the outside of the semiconductor substrate; and

a power supply circuit to supply as electricity an electromagnetic wave energy received from the outside of the semiconductor substrate.

10. A mechanical quantity measuring apparatus according to claim 1, wherein the electromagnetic wave energy is a radio wave.

2. A mechanical quantity measuring apparatus having formed in one main surface of a single crystal semiconductor substrate:

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the semiconductor substrate; and

a power supply circuit to supply as electricity an electromagnetic wave energy received from the outside of the semiconductor substrate.

4. A mechanical quantity measuring apparatus according to claim 2, wherein the single crystal silicon substrate is 100 μ

m or less thick.

3. A mechanical quantity measuring apparatus having formed in one main surface of a single crystal silicon substrate:

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the silicon substrate;

a power supply circuit to supply electricity to these circuits based on at least one of vibrations, sunlight and temperature differences received from the outside of the silicon substrate; and

a connector to electrically connect a power supply ground of any of the circuits on the single crystal silicon substrate to an object to be measured.

5. A mechanical quantity measuring apparatus according to claim 3, wherein the power supply circuit supplies as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits;

wherein a back of the main surface of the single crystal silicon substrate is formed with a bonding surface for bonding to the object to be measured.

6. A mechanical quantity measuring apparatus according to claim 3, wherein the power supply circuit supplies as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits;

wherein a visible mark is formed in a strain measuring direction.

7. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate:

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a temperature sensor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and the temperature sensor and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the silicon substrate; and

a power supply circuit to supply as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits.

8. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate:

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital value;

a transmission circuit to transmit the digital value and an ID number stored in a ROM to the outside of the silicon substrate; and

a power supply circuit to supply as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits.

9. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate:

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the silicon substrate; and

any of a vibration power generation unit, a solar power generation unit and a temperature difference power generation unit provided outside the single crystal silicon substrate to electrically connect to any of the circuits.

11. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the strain sensor has in the silicon substrate a region into which a p-type impurity layer is diffused;

wherein the strain sensor has its longitudinal direction set in <

110>

direction;

wherein the dummy resistor has in the silicon substrate a region into which a p-type impurity layer is diffused;

wherein the dummy resistor has its longitudinal direction set in <

100>

direction.

12. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the strain sensor has formed in the silicon substrate a region into which an n-type impurity layer is diffused;

wherein the n-type region has its longitudinal direction set in <

100>

direction;

wherein the dummy resistor has formed in the silicon substrate a region into which an n-type impurity layer is diffused;

wherein the p-type region has its longitudinal direction set in <

110>

direction.

13. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the strain sensor is formed of a p-type impurity diffusion layer and the dummy resistor is formed of an n-type impurity diffusion layer;

wherein both of the strain sensor and the dummy resistor have their longitudinal directions set in <

110>

direction.

14. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the strain sensor is formed of an n-type impurity diffusion layer and the dummy resistor is formed of a p-type impurity diffusion layer;

wherein both of the strain sensor and the dummy resistor have their longitudinal directions set in <

100>

direction.

15. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the strain sensor is formed of an n-type impurity diffusion layer and the dummy resistor is formed of a p-type impurity diffusion layer;

wherein the strain sensor has its longitudinal direction set in <

100>

direction and the dummy resistor have its longitudinal direction set in <

110>

direction.

16. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate:

at least,

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the silicon substrate; and

a circuit to supply as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits;

wherein the strain sensor is formed by locally diffusing a p-type impurity layer into the silicon substrate;

wherein the strain sensor has its longitudinal direction set in <

110>

direction wherein the dummy resistor is formed by locally diffusing a p-type impurity layer into the silicon substrate;

wherein the dummy resistor has its longitudinal direction set in <

100>

direction.

17. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate:

at least,

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the silicon substrate; and

a circuit to supply as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits;

wherein the strain sensor has an n-type region formed by diffusing an n-type impurity layer into the silicon substrate;

wherein the strain sensor has its longitudinal direction set in <

100>

direction wherein the dummy resistor has a region formed by diffusing an n-type impurity layer into the silicon substrate;

wherein the dummy resistor has its longitudinal direction set in <

110>

direction.

18. A mechanical quantity measuring apparatus having formed in a surface of a silicon substrate:

at least,

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the silicon substrate; and

a circuit to supply as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits;

wherein the strain sensor is formed of a p-type impurity diffusion layer and the dummy resistor is formed of an n-type impurity diffusion layer;

wherein both of the strain sensor and the dummy resistor have their longitudinal directions set in <

110>

direction.

19. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate:

at least,

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

a conversion circuit to amplify a signal from the Wheatstone bridge circuit and convert it into a digital signal;

a transmission circuit to transmit the digital signal to the outside of the silicon substrate; and

a circuit to supply as electricity an electromagnetic wave energy received from the outside of the silicon substrate to any of the circuits;

wherein the strain sensor is formed of an n-type impurity diffusion layer and the dummy resistor is formed of a p-type impurity diffusion layer;

wherein both of the strain sensor and the dummy resistor have their longitudinal directions set in <

100>

direction.

20. A mechanical quantity measuring apparatus having formed in a main surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the single crystal silicon substrate is formed at a back of its main surface with a bonding surface for bonding to an object to be measured.

21. A mechanical quantity measuring apparatus according to claim 20, wherein the single crystal silicon substrate is 100 μ

m or less thick.

22. A mechanical quantity measuring apparatus according to claim 20, wherein a visible mark is formed in a strain measuring direction.

23. A mechanical quantity measuring apparatus having formed in a surface of a single crystal silicon substrate:

a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor; and

a temperature sensor.

24. A mechanical quantity measuring apparatus having formed in a main surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the strain sensor has in the silicon substrate a region into which a p-type impurity layer is diffused;

wherein the strain sensor has its longitudinal direction set in <

110>

direction;

wherein the dummy resistor has in the silicon substrate a region into which a p-type impurity layer is diffused;

wherein the dummy resistor has its longitudinal direction set in a direction perpendicular to the strain sensor.

25. A mechanical quantity measuring apparatus having formed in a main surface of a single crystal silicon substrate a Wheatstone bridge circuit made up of a strain sensor and a dummy resistor;

wherein the strain sensor has in the silicon substrate a region into which an n-type impurity layer is diffused;

wherein the strain sensor has its longitudinal direction set in <

100>

direction;

wherein the dummy resistor has in the silicon substrate a region into which an n-type impurity layer is diffused;

wherein the dummy resistor has its longitudinal direction set in a direction perpendicular to the strain sensor.