Apparatus for Measuring a Mechanical Quantity

• US 20090007686A1
• Filed: 09/15/2008
• Published: 01/08/2009
• Est. Priority Date: 06/17/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: SUMIGAWA, Takashi, Ohta, Hiroyuki
• Granted Patent: US 7,707,894 B2
• Time in Patent Office: Days
• US Class Current: 73/777
• CPC Class Codes: G01B 7/16 for measuring the deformation in a solid, e.g. by resistance strain gauge
• CPC Class Codes: G01B 7/18 using change in resistance
• CPC Class Codes: G01B 7/20 formed by printed-circuit technique
• CPC Class Codes: G01L 1/2206 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
• CPC Class Codes: G01L 1/2262 involving simple electrical bridges
• CPC Class Codes: G01L 5/0047 measuring forces due to residual stresses

Abstract

An apparatus structure and measurement method are provided to retain high precision and high reliability of a semiconductor mechanical quantity measuring apparatus which senses a mechanical quantity and transmits measured information wirelessly. As to a silicon substrate of the semiconductor mechanical quantity measuring apparatus, for example, a ratio of a substrate thickness to a substrate length along a measurement direction is set small, and a ratio of a substrate thickness to a substrate length along a direction perpendicular to the measurement direction is set small. The apparatus upper surface is covered with a protective member. It is possible to measure a strain along a particular direction and realize mechanical quantity measurement with less error and high precision. An impact resistance and environment resistance of the apparatus itself can be improved.

Claims

1. A mechanical quantity measuring apparatus having a strain detector formed on a single crystal semiconductor substrate for detecting a strain, and bonded to or buried in an object to be measured to measure a strain, wherein:

a ratio t/L1 is 0.3 or smaller where t is a thickness of said semiconductor substrate and L1 is a length of said semiconductor substrate along a strain detection direction of said strain detector.

2. A mechanical quantity measuring apparatus having a strain detector formed on a single crystal semiconductor substrate for detecting a strain, and bonded to or buried in an object to be measured to measure a strain, wherein:

a light shielding material is provided covering a principal surface of said semiconductor substrate where said strain detector is formed.

3. The mechanical quantity measuring apparatus according to claim 2, wherein said light shielding material is more difficult to transmit a wavelength having an energy higher than 1.1 eV than other wavelengths.

4. A mechanical quantity measuring apparatus having a strain detector formed on a single crystal semiconductor substrate for detecting a strain, and bonded to or buried in an object to be measured to measure a strain, wherein:

a side plane of said semiconductor substrate includes an area facing a portion of said object to be measured.

5. A mechanical quantity measuring apparatus having a strain detector formed on a single crystal semiconductor substrate for detecting a strain, and bonded to or buried in an object to be measured to measure a strain, wherein:

said semiconductor substrate has a layer formed on a principal surface thereof and having a Young'"'"'s modulus lower than a Young'"'"'s modulus of said semiconductor substrate.

6. The mechanical quantity measuring apparatus according to claim 5, wherein a thickness of said layer having a lower Young'"'"'s modulus is 1 mm or thinner.

7. A mechanical quantity measuring apparatus comprising:

a semiconductor substrate having a strain detector for detecting a strain of an object to be measured and a transmission circuit for transmitting a signal from said strain detector to an external;

a resin film on which said semiconductor substrate is mounted and in which an antenna is formed; and

a high permeability member formed on said antenna on a side of said object to be measured, said high permeability member having an opening in an area where said semiconductor is positioned.

8. A mechanical quantity measuring apparatus having a strain detector formed on a single crystal semiconductor substrate for detecting a strain, and bonded to or buried in an object to be measured to measure a strain, wherein:

a Wheatstone bridge circuit having a plurality of sensor resistor layers is disposed on a principal surface of said single crystal semiconductor substrate; and

resistor layers not constituting said Wheatstone bridge circuit are formed along a longitudinal direction of said strain sensor resistor layers.

9. The mechanical quantity measuring apparatus according to claim 8, wherein said resistors not constituting said circuit have almost a same shape as a shape of said strain sensor resistor layer.

10. A mechanical quantity measuring apparatus having a strain detector formed on a single crystal semiconductor substrate for detecting a strain, and bonded to or buried in an object to be measured to measure a strain, comprising:

n-type diffusion resistors having a <

100>

direction as a longitudinal direction or p-type diffusion resistors having a <

110>

direction as a longitudinal direction, respectively constituting a Wheatstone bridge circuit of said strain detector; and

n-type diffusion resistors having a <

110>

direction as a longitudinal direction or p-type diffusion resistors having a <

100>

direction as a longitudinal direction, respectively constituting a circuit other than said Wheatstone bridge circuit.