# US 9,518,886 B2 · Integrated transducer provided with a temperature sensor and method for sensing a temperature of the transducer

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- Number: US 9,518,886 B2
- Document ID: US9518886B2
- Status: Granted
- Kind: B2
- Application number: 14/950,832
- Filed: 2015-11-24
- Published: 2016-03-17
- Granted: 2016-12-13
- Earliest claimed: 2012-02-17
- Assignees: STMicroelectronics S.r.l.
- Applicants: STMicroelectronics S.r.l.
- Inventors: Lorenzo Baldo; Michele Vaiana; Mario Chiricosta; Mario Maiore; Paul Georges Marie Rose
- Web page: https://patentgrep.com/patent/US9518886B2

## CPC

- G01L 19/0092: {Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature (G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26)}
- G01K 7/01: using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence)
- G01L 9/0054: {integral with a semiconducting diaphragm}
- G01L 9/065: {with temperature compensating means (non electric temperature compensating means G01L19/04)}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

A pressure sensor includes a body made of semiconductor material having a first type of conductivity and a pressure-sensitive structure having the first type of conductivity defining a suspended membrane. One or more piezoresistive elements having a second type of conductivity (P) are formed in the suspended membrane. The piezoresistive elements form, with the pressure-sensitive structure, respective junction diodes. A temperature sensing method includes: generating a first current between conduction terminals common to the junction diodes; detecting a first voltage value between the common conduction terminals when the first current is supplied; and correlating the detected first voltage value to a value of temperature of the diodes. The temperature value thus calculated can be used for correcting the voltage signal generated at output by the pressure sensor when the latter is operated for sensing an applied outside pressure which deforms the suspended membrane.

## Claims

### Claim 1

An apparatus, comprising:
a membrane formed of a semiconductor material having a first conductivity type;
a doped region of a second conductivity type forming a resistor sensor element within the membrane extending between first and second terminals, said doped region further forming with said membrane a junction diode;
a first circuit coupled to the first and second terminals of the resistor sensor element and configured to sense resistive variation of the resistor sensor element between the first and second terminals in response to deflection of the membrane; and
a second circuit coupled to one of the first and second terminals and configured to sense a voltage across the junction diode in response to application of a current to said one of the first and second terminals to pass through the junction diode, said sensed voltage indicative of a temperature of the junction diode.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the current comprises a first current and a second current, and wherein the voltage comprises a corresponding first voltage and second voltage, said second circuit further configured to obtain a difference between the first and second voltages, said difference indicative of the temperature of the junction diode.

### Claim 3 (depends on 1)

The apparatus of claim 1,
wherein the doped region comprises a plurality of doped regions of the second conductivity type forming a plurality of resistor sensor elements within the membrane, the doped regions and membrane further forming a plurality of junction diodes,
wherein the first circuit is coupled to the resistor sensor elements and configured to sense resistive variation of the resistor sensor elements in response to deflection of the membrane; and
wherein the second circuit is coupled to the junction diodes and configured to sense a voltage across the junction diodes in response to application of a current, said voltage indicative of a temperature of the junction diodes.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein said membrane is a pressure sensor, and said sensor element is a piezoresistor.

### Claim 5

A method, comprising:
sensing resistive variation of a resistor sensor element in response to deflection of a membrane, said membrane formed of a semiconductor material of a first conductivity type and said resistor sensor element formed by a doped region of a second conductivity type located within the membrane and having first and second terminals across which said resistive variation is sensed;
wherein said doped region further forms with said membrane a junction diode;
sensing a voltage across the junction diode in response to application of a current to one of the first and second terminals to pass through the junction diode; and
determining from the sensed voltage a temperature of the junction diode.

### Claim 6 (depends on 5)

The method of claim 5, wherein the current comprises a first current and a second current, and wherein the voltage comprises a corresponding first voltage and second voltage, said sensing further comprising calculating a difference between the first and second voltages and wherein determining comprises determining from the voltage difference the temperature of the junction diode.

### Claim 7 (depends on 5)

The method of claim 5,
wherein the doped region comprises a plurality of doped regions of the second conductivity type forming a plurality of resistor sensor elements within the membrane, the doped regions and membrane further forming a plurality of junction diodes,
wherein sensing resistive variation comprises sensing resistive variation of the resistor sensor elements in response to deflection of the membrane; and
wherein sensing the voltage comprises sensing a voltage across the junction diodes in response to application of said current; and
wherein determining comprises determining from the sensed voltage a temperature of the plurality of junction diodes.

### Claim 8 (depends on 5)

The method of claim 5, wherein said membrane is a pressure sensor, and said sensor element is a piezoresistor.

### Claim 9

A method for use with a transducer having a body made of a semiconductor material having a first type of conductivity and including a doped region of a second type of conductivity forming a first resistor transducer element having first and second terminals, said doped region forming the first resistor transducer element further forming with said body a first junction diode, the method comprising:
sensing a temperature of the transducer by:
applying a first current to one of the first and second terminals of the first resistor transducer element to pass through said first junction diode;
detecting a first voltage value across said first junction diode in response to the first current; and
correlating said detected first voltage value to a value of a temperature of said first junction diode; and
sensing a voltage drop across the first and second terminals of the first resistor transducer element that is indicative of change in the transducer.

### Claim 10 (depends on 9)

The method according to claim 9, wherein said transducer is a pressure sensor, the body forming a flexible membrane, and said first resistive transducer element is a piezoresistor.

### Claim 11 (depends on 9)

The method according to claim 9, further comprising:
applying a second current, having a value different from the value of the first current, to one of the first and second terminals of the first resistor transducer element to pass through said first junction diode;
detecting a second voltage value across said first junction diode in response to the second current;
carrying out an operation of subtraction between the first and the second voltage values to obtain a difference value; and
associating said difference value to said value of temperature of said first junction diode.

### Claim 12 (depends on 11)

The method according to claim 11, wherein associating comprises carrying out a linear association.

### Claim 13

A transducer, comprising:
a body made of semiconductor material having a first type of conductivity;
a doped region of a second type of conductivity forming a first resistor transducer element, extending in said body between first and second terminals, said doped region further forming with said body a first junction diode;
a current generator configured to supply a first current to one of the first and second terminals to pass through the first junction diode;
a voltage-measuring device configured to detect a first voltage value across the first junction diode when the first current is supplied to said one of the first and second terminals; and
a processing device configured to acquire the first voltage value and correlate said first voltage value to a value of temperature of the first junction diode, said processing device further configured to detect change in voltage across the first and second terminals of the first resistor transducer element.

### Claim 14 (depends on 13)

The transducer according to claim 13, wherein:
the current generator is moreover configured to supply a second current, having a value different from the value of the first current, to one of the first and second terminals to pass through the first junction diode;
the voltage-measuring device is moreover configured to detect a second voltage value across the first junction diode when the second current is supplied to said one of the first and second terminals; and
the processing device is moreover configured to: acquire the second voltage value; carry out an operation of subtraction between the first voltage value and the second voltage value to obtain a difference value; and associate said difference value to said value of temperature of said first junction diode.

### Claim 15 (depends on 13)

The transducer according to claim 13, wherein the processing device is moreover configured to carry out a linear association between the difference value and the temperature value.

### Claim 16 (depends on 13)

The transducer according to claim 13, wherein said body is a flexible membrane for a pressure sensor, and said first resistive transducer element is a piezoresistor.