Method and device for sensing isotropic stress and providing a compensation for the piezo-hall effect

Patent metadata

Field	Value
Publication number	US-9857247-B2
Application number	US-201314399623-A
Country	US
Kind code	B2
Filing date	May 7, 2013
Priority date	May 7, 2012
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

A method determines isotropic stress by means of a Hall element which includes a plate-shaped area made of a doped semiconductor material and comprises four contacts contacting the plate-shaped area and forming corners of a quadrangle, two neighboring corners of the quadrangle defining an edge thereof. At least one van der Pauw transresistance value in at least one van der Pauw measurement set-up of the Hall element is determined, wherein the four contacts of the Hall element form contact pairs, a contact pair comprising two contacts defining neighboring corners of the quadrangle. One contact pair supplies a current and the other contact pair measures a voltage. A relationship between the supplied current and the measured voltage defines the Van der Pauw transresistance value. The method comprises determining a stress signal which depends on the at least one Van der Pauw transresistance value and determining isotropic stress.

First claim

The invention claimed is:

1. Method for determining isotropic stress by means of a Hall element which has a plate-shaped area made of a doped semiconductor material and comprises four contacts contacting the plate-shaped area, the contacts forming corners of a quadrangle, two neighbouring corners of the quadrangle defining an edge thereof, the method comprising:
determining at least one van der Pauw transresistance value (R vdp1 ) in at least one van der Pauw measurement setup of the Hall element, wherein the four contacts of the Hall element form contact pairs, a contact pair comprising two contacts which are neighbouring corners of the quadrangle, one contact pair being used for supplying a current (I) and the other contact pair being used for measuring a voltage (V vdp1 ), a relationship between the supplied current (I) and the measured voltage (V vdp1 ) defining the Van der Pauw transresistance value (R vdp1 );
determining a stress signal (V S ) which depends at least on the at least one Van der Pauw transresistance value (R vdp1 ); and
determining the isotropic stress by comparing the determined stress signal (V s ) with a predetermined reference stress signal (V Sref (T)) which is temperature-dependent.

2. Method according to claim 1 , furthermore comprising calculating a sheet resistance value (R sq ) from the at least one van der Pauw transresistance value (R vdp1 , R vdp2 ) and using the sheet resistance for determining the stress signal (V s ).

3. Method according to claim 2 , wherein calculating a sheet resistance value (R sq ) from the at least one van der Pauw transresistance value (R vdp1 , R vdp2 ) includes solving the van der Pauw equation

exp
⁡

(

-
π

⁢

R

vdp
⁢

⁢
1

R
sq

)

+

exp
⁡

(

-
π

⁢

R

vdp
⁢

⁢
2

R
sq

)

=
1

or a mathematically equivalent relation which can be derived from this, possibly by using linear relations that exist between transresistance measurements performed on the Hall element.

4. Method according to claim 1 , wherein determining at least one Van der Pauw transresistance value (R vdp1 , R vdp2 ) includes determining the at least one Van der Pauw transresistance value on a Hall element in which the contacts are respectively uniformly angularly displaced by 90°.

5. Method according to claim 1 , wherein determining at least one Van der Pauw transresistance value (R vdp1 , R vdp2 ) comprises:
measuring a first Van der Pauw transresistance value (R vdp1 ) in a first Van der Pauw measurement set-up wherein a first contact pair consisting of neighbouring contacts is used for supplying current and a second contact pair comprising neighbouring contacts is used for measuring a voltage, the second contact pair being different from the first contact pair; and
measuring a second Van der Pauw transresistance value (R vdp2 ) in a second Van der Pauw measurement set-up wherein a third contact pair consisting of neighbouring contacts is used for supplying current and a fourth contact pair consisting of neighbouring contacts is used for measuring a voltage, the third contact pair being different from the first and the fourth contact pair and the fourth contact pair being different from the second contact pair, all contact pairs consisting of two out of the four contacts of the plate.

6. Method according to claim 1 , wherein determining at least one Van der Pauw transresistance value (R vdp1 , R vdp2 ) comprises
measuring a first Van der Pauw transresistance value (R vdp1 ) in a first Van der Pauw measurement set-up wherein a first contact pair consisting of neighbouring contacts is used for supplying current and a second contact pair consisting of neighbouring contacts is used for measuring a voltage, the second contact pair being different from the first contact pair; and
measuring at least a first diagonal transresistance value (R diag1 ) in a first diagonal measurement set-up on the Hall element, a fifth contact pair being used for supplying a current and a sixth contact pair being used for measuring a voltage, the contacts of the fifth contact pair being interleaved along the edge of the quadrangle with the contacts of the sixth contact pair, all contact pairs consisting of two out of the four contacts of the plate, a relationship between the supplied current and the measured voltage defining the diagonal transresistance value (R diag1 ); and
calculating a second Van der Pauw transresistance value from the first Van der Pauw transresistance value (R vdp1 ) and the at least first diagonal transresistance (R diag1 ).

7. Method according to claim 6 , wherein measuring at least a first diagonal transresistance value comprises
measuring a first diagonal transresistance value (R diag1 ) in a first diagonal measurement set-up; and
measuring a second diagonal transresistance value (R diag2 ) in a second diagonal measurement set-up different from the first diagonal measurement set-up, and wherein calculating a second Van der Pauw transresistance (R VdP2 ) value comprises calculating the second Van der Pauw transresistance value (R VdP2 ) from the first Van der Pauw transresistance value (R vdp1 ) and the sum or difference of the two diagonal transresistances.

8. Method according to claim 1 , wherein determining the stress signal (V S ) which depends at least on the at least one Van der Pauw transresistance value (R vdp1 ) includes taking the stress signal (V s ) proportional to the sheet resistance value (R sq ).

9. Method for determining a component of a magnetic field by means of a Hall element which has a plate-shaped area made of a doped semiconductor material and comprises four contacts contacting the plate-shaped area, the Hall element being located in the magnetic field, the method comprising:
determining the relative stress signal (V Srel ) by means of the Hall element, according to claim 7 ;
calculating a Hall voltage value (V Hall ) proportional to the magnetic field by adding a first diagonal voltage proportional t

Assignees

• Melexis Technologies Nv

Inventors

• Huber Samuel
• Raman Johan
• Rombouts Pieter
• Van Der Wiel Appolonius Jacobus

Classifications

• G01L1/2293 Primary

  of the semi-conductor type · CPC title

• G01L1/18

  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 title

• G01L1/125

  by using magnetostrictive means (magnetostrictive sensors H10N35/101) · CPC title

• G01R33/0035

  Calibration of single magnetic sensors, e.g. integrated calibration · CPC title

• G01R33/07 Primary

  Hall effect devices · CPC title