Apparatus and method for accurate measurement and mapping of forward and reverse-bias current-voltage characteristics of large area lateral p-n junctions

Patent metadata

Field	Value
Publication number	US-9746514-B2
Application number	US-201414475330-A
Country	US
Kind code	B2
Filing date	Sep 2, 2014
Priority date	Sep 4, 2013
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

Methods and apparatus for providing measurements in p-n junctions and taking into account the lateral current for improved accuracy are disclosed. The lateral current may be controlled, allowing the spreading of the current to be reduced or substantially eliminated. Alternatively or additionally, the lateral current may be measured, allowing a more accurate normal current to be calculated by compensating for the measured spreading. In addition, the techniques utilized for controlling the lateral current and the techniques utilized for measuring the lateral current may also be implemented jointly.

First claim

What is claimed is:

1. An apparatus, comprising:
a first probe configured for establishing an electrical connection with a surface of a first layer of a p-n junction, the established electrical connection covering an area of the surface of the first layer of the p-n junction optimized to minimize a lateral current;
a second probe configured for electrically contacting both the first layer and a second layer forming the p-n junction;
a measurement unit electrically connected to the first probe and the second probe, the measurement unit configured for measuring at least one of: a voltage between the first and second probes and a current between the first and second probes when the first and the second probes are stimulated;
a guard loop configured for preventing the lateral current from the first probe; and
wherein at least one of: a voltage and a current applied to the guard loop is adjustable based on a measured surface voltage differential between the first probe and the guard loop.

2. The apparatus of claim 1 , wherein the first probe is a disc probe having a sufficiently large diameter to diminish the lateral current flow outside of the disc probe.

3. The apparatus of claim 1 , wherein the area covered by the first probe is optimized for accuracy and spatial mapping resolution such that a ratio of the lateral current to a normal current under the first probe is within a required accuracy of density leakage current measurement.

4. The apparatus of claim 1 , wherein the first probe is made from a conductive elastic polymer.

5. The apparatus of claim 1 , wherein the first probe is mounted to a mechanical actuator to provide full compliance to angular offsets of the surface of the first layer of the p-n junction.

6. The apparatus of claim 1 , further comprising:
at least one voltage measurement probe configured for measuring a surface voltage at a location within the area of the surface covered by the first probe.

7. The apparatus of claim 6 , wherein the at least one voltage measurement probe is a disc probe providing contact with the surface of the first layer of the p-n junction inside of an opening defined by the first probe.

8. The apparatus of claim 6 , wherein the at least one voltage measurement probe is a non-contact probe placed near the surface of the first layer of the p-n junction inside of an opening defined by the first probe.

9. The apparatus of claim 6 , wherein the first probe is a ring probe having a sufficiently large diameter to diminish the lateral current flow outside of the ring probe, and wherein the at least one voltage measurement probe is configured for measuring the surface voltage at an opening defined at a center of the ring probe.

10. The apparatus of claim 1 , further comprising: a plurality of electrical contacts established between the first probe and the guard loop, the plurality of electrical contacts configured for measuring a surface voltage drop between the first probe and the guard loop.

11. The apparatus of claim 1 , wherein the surface voltage differential is measured using at least one non-contact probe.

12. An apparatus, comprising:
a first probe configured for establishing an electrical connection with a surface of a first layer of a p-n junction;
a second probe configured for contacting the p-n junction;
a plurality of voltage measurement probes configured for measuring a surface voltage drop;
a guard loop configured for preventing a lateral current from the first probe, wherein at least one of a voltage and a current applied to the guard loop is adjustable based on the measured surface voltage drop; and
a measurement unit electrically connected to the first probe and the second probe, the measurement unit configured for measuring at least one of: a voltage between the first and second probes and a current between the first and second probes when the first and second probes are stimulated.

13. The apparatus of claim 12 , wherein the electrical connection established by the first probe covers an area of the surface of the first layer of the p-n junction optimized to minimize the lateral current.

14. The apparatus of claim 13 , wherein the first probe is a disc probe having a sufficiently large diameter to diminish the lateral current flow outside of the disc probe.

15. The apparatus of claim 14 , wherein the disc probe is made from a conductive elastic polymer.

16. The apparatus of claim 15 , wherein the disc probe is mounted to a mechanical actuator and assembly to provide full compliance to angular offsets of the surface of the first layer of the p-n junction.

17. The apparatus of claim 12 , wherein one of the plurality of voltage measurement probes is configured for measuring a surface voltage at a location within the area of the surface covered by the first probe.

18. The apparatus of claim 17 , wherein the first probe is a ring probe having a sufficiently large diameter to diminish the lateral current flow outside of the ring probe, and wherein said one of the plurality of voltage measurement probes is configured for measuring the surface voltage at an opening defined at a center of the ring probe.

19. The apparatus of claim 12 , wherein at least one of the plurality of voltage measurement probes is configured for measuring a surface voltage at a location between the first probe and the guard loop.

20. The apparatus of claim 12 , wherein at least one of the plurality of voltage measurement probes is a vibrating non-contact probe.

21. An apparatus, comprising:
a first probe configured for establishing an electrical connection with a surface of a first layer of a p-n junction;
a second probe configured for contacting the p-n junction;
a plurality of voltage measurement probes configured for measuring surface voltages at different distances away from the first probe when the first and second probes are stimulated;
at least one additional probe configured for facilitating measurement of a sheet resistance of the first layer of the p-n junction; and
a measurement unit configured for calculating a lateral current in proximity to the first probe based on the measured surface voltages at different distances away from the first probe and the measured sheet resistance.

22. The apparatus of claim 21 , wherein the first probe, the plurality of voltage measurement probes, and the at least one additional probe jointly form a four point probe (4PP) for measuring the sheet resistance of the first layer of the p-n junction.

23. The apparatus of claim 21 , wherein the at least one additional probe includes a non-contact junction photovoltage probe for measuring the sheet resistance of the first layer of the p-n junction.

24. The apparatus of claim 21 , wherein the second probe is connected to a second layer of the p-n junction.

25. The apparatus of claim 21 , wherein the lateral current [I] in proximity to the first probe is determined based on:
a current J utilized to stimulate the first and the second probes;
at least two measured surface voltages V 1 and V 2 measured at distances r 1 and r 2 away from the first probe, r 1 <r 2 ; and
the measured sheet resistance Rsp.

26. The apparatus of claim 25 , wherein a density of leakage current j in proximity to the first probe is determined as:

J
norm

≅

Assignees

• Kla Tencor Corp

Inventors

• Kelly-Morgan Ian Sierra Gabriel
• Faifer Vladimir N
• Real James A
• Salunke Biren
• Nyffenegger Ralph

Classifications

• H10P74/207

  Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics · CPC title

• G01R27/08

  Measuring resistance by measuring both voltage and current · CPC title

• G01R1/07

  Non contact-making probes · CPC title

• G01N27/00

  Investigating or analysing materials by the use of electric, electrochemical, or magnetic means (G01N3/00 – G01N25/00 take precedence; measurement or testing of electric or magnetic variables or of electric or magnetic properties of materials G01R) · CPC title

• G01R31/2648 Primary

  Characterising semiconductor materials (testing of materials or semi-finished products G01R31/2831; testing during manufacture H10P74/00) · CPC title