Method for determining a three-dimensional stress field of an object, an integrated structure in particular, and corresponding system

Patent metadata

Field	Value
Publication number	US-9638589-B2
Application number	US-201414311497-A
Country	US
Kind code	B2
Filing date	Jun 23, 2014
Priority date	Jun 25, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A method and corresponding system are provided for determining a three-dimensional stress field of an object having a flat surface. At least four flat resistors are placed on the flat surface of the object, with at least one of the resistors having a geometry different from that of the others. A variation of resistance of the resistors is measured. The three-dimensional stress field is determined from a system of equations involving the stress field, values of variations of the measured resistive values and sensitivity parameters of the resistors.

First claim

The invention claimed is:

1. A method for determining a three-dimensional stress field of an object having a flat surface, the method comprising:
measuring variations in resistive values of a group of resistors on the flat surface of the object, with each resistor in the group of resistors having a same material concentration level, and with the group of resistors comprising at least four flat resistors, each resistor having a resistive value, and each resistor having a geometric shape defined by a line width and a line spacing forming the geometric shape, and at least one of the resistors having a geometric shape that is different from the geometric shape of the other resistors; and
determining the three-dimensional stress field from a system of equations and based upon the measured variations in the resistive values and sensitivity parameters of the resistors, the sensitivity parameters including at least one of a longitudinal sensitivity, a transverse sensitivity and a vertical sensitivity.

2. The method according to claim 1 , wherein all of the flat resistors in the group of resistors comprise a same material.

3. The method according to claim 1 , wherein the object is configured as an integrated structure.

4. The method according to claim 1 , further comprising:
forming the object with the flat surface; and
placing the group of resistors on the flat surface of the object.

5. The method according to claim 1 , wherein measuring the variations in the resistive values comprises:
performing a first measurement on the resistive values of the group of resistors;
introducing mechanical stress on the object after the first measurement;
performing a second measurement on the resistive values of the group of resistors after the at least one step; and
comparing the resistive values from the first measurement with the resistive values from the second measurement to determine the variations in resistive values.

6. The method according to claim 1 , further comprising determining the sensitivity parameters of the resistors based on a simulation of the object or a test performed on a test object.

7. A method for determining a three-dimensional stress field of an object having a flat surface, the method comprising:
placing a group of resistors on the flat surface of the object, the group of resistors comprising at least four flat resistors, with each resistor in the group of resistors having a same material concentration level, and with each flat resistor having a resistive value, and each resistor having a geometric shape defined by a line width and a line spacing forming the geometric shape, and at least one of the resistors having a geometric shape that is different from the geometric shape of the other resistors;
performing a first measurement on the resistive values of the group of resistors;
introducing mechanical stress on the object;
performing a second measurement on the resistive values of the group of resistors after introduction of the mechanical stress on the object;
comparing the resistive values from the first measurement with the resistive values from the second measurement to determine variations in the resistive values; and
determining the three-dimensional stress field from a system of equations and based upon the measured variations in the resistive values and sensitivity parameters of the resistors resistive values and sensitivity parameters of the resistors, the sensitivity parameters including at least one of a longitudinal sensitivity, a transverse sensitivity and a vertical sensitivity.

8. The method according to claim 7 , wherein all of the flat resistors in the group of resistors comprise a same material.

9. The method according to claim 7 , wherein the object is configured as an integrated structure.

10. The method according to claim 7 , further comprising forming the object with the flat surface.

11. The method according to claim 7 , further comprising determining the sensitivity parameters of the flat resistors based on simulation of the object or testing performed on a test object.

12. A method for determining a stress field of an object, the method comprising:
measuring variations in resistive values of a group of resistors on a surface of the object, the group of resistors comprising a plurality of resistors, with each resistor in the group of resistors having a same material concentration level, and with each resistor having a resistive value, and each resistor having a geometric shape defined by a line width and a line spacing forming the geometric shape, and at least one of the resistors having a geometric shape that is different from the geometric shape of the other resistors; and
determining the stress field based upon the measured variations in the resistive values and sensitivity parameters of the resistors, the sensitivity parameters including at least one of a longitudinal sensitivity, a transverse sensitivity and a vertical sensitivity.

13. The method according to claim 12 , wherein all of the resistors in the group of resistors comprise a same material.

14. The method according to claim 12 , wherein the object is configured as an integrated structure.

15. The method according to claim 12 , further comprising:
forming the object with a flat surface; and
placing the group of resistors on the flat surface of the object.

16. The method according to claim 12 , wherein measuring the variations in the resistive values comprises:
performing a first measurement on the resistive values of the group of resistors;
introducing mechanical stress on the object after the first measurement;
performing a second measurement on the resistive values of the group of resistors after the at least one step; and
comparing the resistive values from the first measurement with the resistive values from the second measurement to determine the variations in resistive values.

17. The method according to claim 12 , further comprising determining the sensitivity parameters of the resistors based on a simulation of the object or a test performed on a test object.

18. A system comprising:
an object having a flat surface;
at least four flat resistors on the flat surface of said object, each resistor having a same material concentration level, and with each resistor having a geometric shape defined by a line width and a line spacing forming the geometric shape, and at least one of the resistors having a geometric shape that is different from the geometric shape of the other resistors;
a measurement unit configured to measure a variation of resistive values of said at least four flat resistors; and
a stress determination unit configured to determine a stress field from a system of equations involving the stress field, the measured variations in said at least four flat resistors, and sensitivity parameters of said at least four flat resistors, the sensitivity parameters including at least one of a longitudinal sensitivity, a transverse sensitivity and a vertical sensitivity.

19. The system according to claim 18 , wherein all of said at least four flat resistors comprise a same material.

20. The system according to claim 18 , wherein said object is configured as an integrated structure.

21. The system according to claim 18 , wherein said at least four flat resistors comprise a conductive material comprising at least one of aluminium and copper.

22. The system according to claim 18 , wherein each resistor has a resistive serpentine shape, and wherein said at

Assignees

• St Microelectronics Sa
• St Microelectronics Crolles 2 Sas

Inventors

• Fiori Vincent
• Bar Pierre
• Gallois-Garreignot Sébastien

Classifications

• H10P74/277

  Circuits for electrically characterising or monitoring manufacturing processes, e.g. circuits in tested chips or circuits in testing wafers · CPC title

• G01B7/18

  using change in resistance · CPC title

• G01L1/2287

  constructional details of the strain gauges (adjustable resistors H01C10/00) · CPC title

• G01L1/20 Primary

  by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids (of piezo-resistive materials G01L1/18); by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress · CPC title

• G01L25/00

  Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency · CPC title