METHOD OF DETERMINING AN ELECTRICAL PROPERTY OF A TEST SAMPLE

• US 20100271059A1
• Filed: 09/03/2008
• Published: 10/28/2010
• Est. Priority Date: 09/03/2007
• Status: Active Grant

• Current Assignee: CAPRES A/S (KLA Corporation)
• Original Assignee: CAPRES A/S (KLA Corporation)
• Inventors: Hansen, Ole, Petersen, Dirch H.
• Granted Patent: US 8,907,690 B2
• Time in Patent Office: Days
• US Class Current: 324/754.30
• CPC Class Codes: G01R 31/2648 Characterising semiconductor materials testing of materials or semi-finished products G01R31/2831; testing during manufacture H01L22/00
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method of obtaining an electrical property of a test sample, comprising a non-conductive area and a conductive or semi-conductive test area, by performing multiple measurements using a multi-point probe. The method comprising the steps of providing a magnetic field having field lines passing perpendicularly through the test area, bringing the probe into a first position on the test area, the conductive tips of the probe being in contact with the test area, determining a position for each tip relative to the boundary between the non-conductive area and the test area, determining distances between each tip, selecting one tip to be a current source positioned between conductive tips being used for determining a voltage in the test sample, performing a first measurement, moving the probe and performing a second measurement, calculating on the basis of the first and second measurement the electrical property of the test area.

Claims

1. A method of determining an electrical property of a test sample by utilising the so-called Hall effect, said test sample comprising a non-conductive area and a test area, said test area being a conductive or semi-conductive test area, a boundary defined between said non-conductive area and said test area, said method including using a test probe comprising a probe body having a planar probe surface and a first multitude of probe arms extending from said probe body parallel to said planar probe surface, said test probe further comprising a first multitude of electrical conductive tips each supported by a respective probe arm, said electrical conductive tips adapted to establish electrical contact to said test area,

said method comprising the steps of:

providing a magnetic field having field lines passing perpendicularly through said test area,

bringing said test probe into a first position on said test area, said first multitude of electrical conductive tips being in contact with said test area,

determining the shortest distance between each of said first multitude of electrical conductive tips and said boundary,

determining distances between each of said first multitude of electrical conductive tips,

selecting one electrical conductive tip of said first multitude to be a current source, said one electrical conductive tip being selected so that said one electrical conductive tip is positioned between first and second electrical conductive tips of said first multitude being used for determining a voltage in said test sample,

performing a series of measurements where the ratio between said shortest distance between said one electrical conductive tip and said boundary, and the distance between said first and said second electrical conductive tips is varied, and

calculating on the basis of said series of measurements an electrical property of said conductive test area.

2. The method according to claim 1, wherein said series of measurements includes measurements performed at least at first and second non-identical positions.

3. The method according to claim 1, wherein said series of measurements includes measurements performed by using a different electrical conductive tip as a current source for each measurement.

4. The method according to claim 1, wherein said boundary has a shape selected from the group consisting of one or more of linear, rectangular, box-shaped, square, triangular, round, polygonal, arbitrarily shaped, and any combination hereof.

5. The method according to claim 1, wherein said magnetic field is stationary.

6. The method according to claim 5, wherein said magnetic field has a field strength in the order of 200 mT-700 mT.

7. The method according to claim 1, wherein said first multitude of probe tips is positioned on a line.

8. The method according to claim 7, wherein during said measurements said test probe is oriented so that said probe tips are positioned parallel to a part of said boundary.

10. The method according to claim 2, wherein said first and second non-identical positions are reached by moving said test probe from said first position to said second position while said electrical conductive tips are in contact with said conductive test area.

11. The method according to claim 2, wherein said first and second non-identical positions are reached by moving said probe arms out of contact with said conductive test area and moving said probe relative to said conductive test area before bringing said electrical conductive tips into contact with said conductive test area at the second position.

12. The method according to claim 1, wherein said electrical property is selected from the group consisting of one or more of sheet resistance, active implant dose, and carrier mobility.

13. The method according to claim 1, wherein the measurements are fitted into a data model.

14. The method according to claim 1, wherein said method further comprises calculating at least one of a correction factor and a correction function for fitting said measurements to theoretical data.

15. The method according to claim 1, wherein said test area defines a size allowing said measurements and said calculations to be performed using equations for infinite sheet calculations.

16. The method according to claim 1, wherein said method comprises using a numerical method.

21. The method according to claim 1, wherein said magnetic field is a varying magnetic field.

22. The method according to claim 16, wherein said numerical method is a finite element method.

9. (canceled)

17. A method of determining an electrical property of a test sample by utilising the so-called Hall effect, said test sample comprising a non-conductive area and a conductive test area, a boundary defined between said non-conductive area and said conductive test area, said method including using a test probe comprising a probe body having a planar probe surface and four probe arms extending from said probe body parallel to said planar probe surface, said probe further comprising four electrical conductive tips each supported by a respective probe arm, said electrical conductive tips adapted to establish electrical contact to said test area,

said method comprising the steps of:

providing a magnetic field being perpendicular to said conductive test area,

bringing said test probe into a first position on said conductive test area, said four electrical conductive tips being in contact with said conductive test area,

determining a position for each of said four electrical conductive tips relative to said boundary,

determining distances between each of said four electrical conductive tips,

selecting one of said electrical conductive tips to be a current source, said one electrical conductive tip being selected so that said one electrical conductive tip is positioned between first and second electrical conductive tips being used for determining a voltage in said test sample,

performing a first measurement by applying a current to said one electrical conductive tip and determining said voltage across said first and a second electrical conductive tips,

moving said probe into a second position remote from said first position,

performing a second measurement by applying a current to said one electrical conductive tip and determining said voltage across said first and a second electrical conductive tips, and

calculating on the basis of said first and second measurements an electrical property of said conductive test area.

18. A method of determining an electrical property of a test sample by utilising the so-called Hall effect, said test sample comprising a non-conductive area and a conductive test area, a boundary defined between said non-conductive area and said conductive test area, said method including using a test probe comprising a probe body having a planar probe surface and four probe arms extending from said probe body parallel to said planar probe surface, said probe further comprising four electrical conductive tips each supported by a respective probe arm, said electrical conductive tips adapted to establish electrical contact to said test area,

said method comprising the steps of:

providing a magnetic field being perpendicular to said conductive test area,

bringing said probe into a first position on said conductive test area, said four electrical conductive tips being in contact with said conductive test area,

determining a position for each of said four electrical conductive tips relative to said boundary,

determining distances between each of said four electrical conductive tips,

selecting one electrical conductive tip to be a current source, said one electrical conductive tip being selected so that said one electrical conductive tip is positioned between first and second electrical conductive tips being used for determining a voltage in said test sample,

performing a first measurement by applying a current to said one electrical conductive tip and determining said voltage across said first and a second electrical conductive tips,

moving said probe into a second position remote from said first position,

performing a second measurement by applying a current to said one electrical conductive tip and determining said voltage across said first and a second electrical conductive tips, and

calculating on the basis of said first and second measurement measurements an electrical property of said conductive test area.

19-20. -20. (canceled)

23. A system for determining an electrical property of a test sample using the so-called Hall effect, the test sample comprising a non-conductive area, a conductive test area, and a boundary defined between the non-conductive area and the conductive test area, the system including:

a test probe, comprising;

(a) a probe body having a planar probe surface and a plurality of probe arms extending from the probe body parallel to the planar probe surface; and

(b) a plurality of electrical conductive tips, each of the tips being supported by a respective probe arm and adapted to establish electrical contact to the test area;

a test probe holder that receives the test probe and a test sample holder that receives and holds the test sample, the test probe holder and the test sample holder being movable relative to each other;

means for providing a magnetic field having field lines passing perpendicularly through the test area;

means for moving the test probe into a position in which the plurality of electrical conductive tips are in contact with the test area; and

a microprocessor system including a software implementation of a method comprising the steps of;

determining the shortest distance between each of the plurality of electrical conductive tips and the boundary;

determining distances between each of the plurality of electrical conductive tips;

selecting one electrical conductive tip of the plurality of electrical conductive tips to be a current source, the one electrical conductive tip being selected so that the one electrical conductive tip is positioned between first and second electrical conductive tips of the plurality of electrical conductive tips that are being used for determining a voltage in said test sample;

performing a series of measurements where the ratio between the shortest distance between the one electrical conductive tip and the boundary, and the distance between the first and second electrical conductive tips, is varied; and

calculating on the basis of the series of measurements an electrical property of the conductive test area.

24. The system according to claim 23, wherein the series of measurements includes measurements performed at least at a first position and a second position.

25. The system according to claim 23, wherein the series of measurements includes measurements performed by using a different electrical conductive tip as a current source for each measurement.

26. The system according to claim 23, wherein the magnetic field has a field strength on the order of 200 mT-700 mT.

27. The system according to claim 23, wherein the plurality of electrical conductive probe tips is positioned on a line.

28. The system according to claim 27, wherein during the series of measurements, the test probe is oriented so that the probe tips are positioned parallel to a part of the boundary.

30. The system according to claim 24, wherein the first and second positions are reached by moving the test probe from the first position to the second position while the electrical conductive tips are in contact with the conductive test area.

31. The system according to claim 24, wherein the second position is reached by moving the probe arms out of contact with the conductive test area and moving the test probe relative to the conductive test area before bringing the electrical conductive tips into contact with the conductive test area at the second position.

32. The system according to claim 23, wherein the electrical property is selected from the group consisting of one or more of sheet resistance, active implant dose, and carrier mobility.

33. The system according to claim 23, wherein the measurements are fitted into a data model.

34. The system according to claim 23, wherein the method further comprises calculating at least one of a correction factor and a correction function for fitting the measurements to theoretical data.

35. The system according to claim 23, wherein the test area defines a size allowing the measurements and the calculations to be performed using equations for infinite sheet calculations.

36. The system according to claim 23, wherein the method comprises using a numerical method.

37. The system according to claim 36, wherein the numerical method is a finite element method.