Integrated transducer provided with a temperature sensor and method for sensing a temperature of the transducer

Patent metadata

Field	Value
Publication number	US-9534974-B2
Application number	US-201313757146-A
Country	US
Kind code	B2
Filing date	Feb 1, 2013
Priority date	Feb 17, 2012
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

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.

First claim

What is claimed is:

1. A method for sensing a temperature of 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:
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.

2. The method according to claim 1 , wherein said transducer is a pressure sensor, the body forming a flexible membrane, and said first resistive transducer element is a piezoresistor.

3. The method according to claim 1 , 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 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.

4. The method according to claim 3 , wherein associating comprises carrying out a linear association.

5. A method for sensing a temperature of a transducer having a body made of a semiconductor material having a first type of conductivity and including a first transducer element having a second type of conductivity and a second transducer element having the second type of conductivity, said first transducer element forming with said body a first junction diode and said second transducer element forming with said body a second junction diode, said first and second junction diodes being connected in parallel between common conduction terminals, the method comprising:
biasing the common conduction terminals so as to generate a first current through the first and second junction diodes;
detecting a first voltage value across the common conduction terminals when the first current is supplied;
biasing the common conduction terminals so as to generate a second current, having a value different from the value of the first current, through the first and second junction diodes;
detecting a second voltage value across said common conduction terminals when the second current is supplied;
carrying out an operation of subtraction between the first and second voltage values to obtain a difference value; and
associating said difference value to a value of temperature of said first and second junction diodes.

6. A method for sensing a temperature of a transducer having a body made of a semiconductor material having a first type of conductivity and including a first transducer element having a second type of conductivity and a second transducer element having the second type of conductivity, said first transducer element forming with said body a first junction diode and said second transducer element forming with said body a second junction diode, the method comprising:
generating a first current through said first junction diode;
detecting a first voltage value across said first junction diode when the first current is supplied;
generating a second current equal to the first current through said second junction diode;
detecting a second voltage value across said second junction diode when the second current is supplied;
carrying out an operation of subtraction between the first voltage value and the second voltage value to obtain a difference value; and
associating said difference value to a value of temperature of said first and second junction diodes.

7. 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 of the first resistor transducer element 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; and
a processing device configured to acquire the first voltage value detected and correlate said first voltage value to a value of temperature of the first junction diode.

8. The transducer according to claim 7 , wherein:
the current generator is moreover configured to supply a second current, having a value different from the value of the first current, to 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; and
the processing device is moreover configured to: acquire the second value of the voltage detected; carry out an operation of subtraction between the first value and the second value of the voltage detected to obtain a difference value; and associate said difference value to said value of temperature of said first junction diode.

9. The transducer according to claim 8 , wherein the processing device is moreover configured to carry out a linear association between the difference value and the temperature value.

10. A transducer, comprising:
a body made of semiconductor material having a first type of conductivity;
a first transducer element, extending in said body, having a second type of conductivity, and forming with said body a first junction diode;
a second transducer element, extending in said body, having the second type of conductivity and forming with said body a second junction diode, said first and second junction diodes being connected in parallel between common conduction terminals,
a current generator configured to supply a first current and a second current to the common conduction terminals, the second current having a value different from the value of the first current,
a voltage-measuring device configured to detect a first voltage value across the common conduction terminals when the first current is supplied, and detect a second voltage value across the common conduction terminals when the second current is supplied, and
a processing device configured to 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 a value of temperature of said first and second junction diodes.

11. The transducer according to claim 10 , further comprising a third transducer element and a fourth transducer element having the second type of conductivity, said third and fourth transducer elements forming with said body a respective third junction diode and fourth junction diode, said first, second, third and fourth junction diodes being connected in parallel between said common conduction terminals,
said first, second, third, and fourth transducer elements being moreover connected together to form a Wheatstone bridge.

12. The transducer according to claim 11 , wherein the body is a flexible membrane, and said first, second, third, and fourth transducer elements are piezoresistors diffused in the sensing structure, said transducer being

Assignees

• St Microelectronics Srl

Inventors

• Vaiana Michele
• Chiricosta Mario
• Maiore Mario
• Baldo Lorenzo
• Rose Paul Georges Marie

Classifications

• G01L9/0054

  integral with a semiconducting diaphragm · CPC title

• G01L9/065

  with temperature compensating means (non electric temperature compensating means G01L19/04) · CPC title

• G01K7/01 Primary

  using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence) · CPC title

• G01L19/0092 Primary

  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) · CPC title