Apparatus and method for detecting photon emissions from transistors

• US 7,323,862 B2
• Filed: 04/25/2006
• Issued: 01/29/2008
• Est. Priority Date: 09/03/2002
• Status: Expired due to Fees

• Current Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Credence Systems Corporation (COHU Incorporated)
• Inventors: Desplats, Romain, Le Coupanec, Patricia, Kasapi, Steven, Perdu, Philippe, Lo, William K.
• Primary Examiner(s): Nguyen; Ha Tran
• Assistant Examiner(s): Vazquez; Arleen M.
• Application Number:
  US11/380,044
• Publication Number:
  US 20060181268A1
• Time in Patent Office: 644 Days
• Field of Search: 324/750, 324/768, 324/769, 324/158.1, 324/764
• US Class Current: 324/762.09
• CPC Class Codes: G01R 31/2656 using non-ionising electromagnetic radiation, e.g. optical radiation
• CPC Class Codes: G01R 31/311 of integrated circuits G01R31/31728 takes precedence

Abstract

A system, apparatus, and method for analyzing photon emission data to discriminate between photons emitted by transistors and photons emitted by background sources. The analysis involves spatial and/or temporal correlation of photon emissions. After correlation, the analysis may further involve obtaining a likelihood that the correlated photons were emitted by a transistor. After correlation, the analysis may also further involve assigning a weight to individual photon emissions as a function of the correlation. The weight, in some instances, reflecting a likelihood that the photons were emitted by a transistor. The analysis may further involve automatically identifying transistors in a photon emission image.

Claims

1. A method for analyzing and displaying collected photon emissions data of a plurality of photons to discriminate between photons emitted from a transistor and photons emitted from other sources, the collected photon emissions data of each photon comprising a spatial component and a temporal component respectively corresponding with a location where the photon was detected and a time when the photon was detected, the method comprising:

correlating the collected photon emissions data of each photon with the collected photon emission data of some or all of the plurality of photons to obtain correlated photon emission data for the photon;

assigning a weight to each photon as a function of the correlated photon emission data of the photon;

determining from the weight of each photon a likelihood that the photon originated from a transistor photon emission; and

displaying the likelihood.

2. The method of claim 1,

wherein the correlation of the collected photon emission data includes spatially correlating the photon emission data, and

wherein the operation of spatially correlating the collected photon emission data comprises obtaining a first grouping of spatially similar photon emissions from the collected photon emission data.

3. The method of claim 1,

wherein the plurality of photons includes at least a first photon and a second photon,

wherein the collected photon emission data corresponds to at least a first photon emission having a first spatial component and a first temporal component and at least a second photon emission having a second spatial component and a second temporal component,

wherein the correlation of the collected photon emission data includes spatially correlating the photon emission data and temporally correlating the photon emission data, and

wherein the operation of spatially correlating the collected photon emission data comprises determining if the first spatial component is within a spatial range of the second spatial component.

4. The method of claim 2,

wherein the correlation of the collected photon emission data further includes temporally correlating the photon emission data, and

wherein the operation of temporally correlating the collected photon emission data comprises obtaining a second grouping of temporally similar photon emissions from the first grouping of spatially similar photon emissions.

5. The method of claim 3 wherein the operation of temporally correlating the collected photon emission data comprises determining if the first temporal component is within a temporal range of the second temporal component.

6. The method of claim 2 wherein the operation of obtaining a first grouping of spatially similar photon emissions comprises:

receiving an indication of a spatial range;

identifying a first photon with a first spatial component;

identifying a spatial range about the first photon;

analyzing the collected photon emission data to identify a number of photons within the spatial range about the first photon; and

including the photons within the spatial range about the first photon in the first grouping when the number of photons within the spatial range about the first photon meets a threshold.

7. The method of claim 6 wherein the first spatial component comprises a x-value and a y-value and the spatial range comprises a x-range and a y-range.

8. The method of claim 7 wherein the spatial range about the first photon comprises a rectangular region defined by:

(x-value-x-range/2, x-value+x-range/2), (y-value-y-range/2, y-value+y-range/2).

9. The method of claim 2 wherein the operation of obtaining a first grouping of spatially similar photon emissions comprises:

receiving an indication of a spatial and temporal range;

identifying a first photon with a first spatial and temporal component;

identifying a spatial and temporal range about the first photon;

analyzing the collected photon emission data to identify a number of photons within the spatial and temporal range about the first photon; and

including the photons within the spatial and temporal range in the first grouping when the number of photons within the spatial and temporal range about the first photon meets a threshold.

10. The method of claim 9 wherein the first spatial and temporal component comprises a x-value, a y-value and a time value, the spatial and temporal range comprises a x-range, a y-range, and a time range.

11. The method of claim 10 wherein the spatial and temporal range about the first photon comprises a brick shaped region defined by:

(x-value-x-range/2, x-value+x-range/2), (y-value-y-range/2, y-value+y-range/2), (time value-time range/2, time value+time range/2).

12. A picosecond imaging circuit analysis probe system configured to perform the method of claim 1.

13. The method of claim 1, further comprising:

searching for high weight photons among the plurality of photons within incrementally increasing three-dimensional spaces, the high weight photons having a weight above a first threshold value and the three-dimensional spaces having two spatial dimensions and a time dimension;

defining a three-dimensional range about a first high weight photon, the three-dimensional range having two spatial dimensions and a time dimension;

determining a number of the high weight photons within the three-dimensional range about the first high weight photon;

determining whether the number of high weight photons within the three-dimensional range exceeds a second threshold value, the second threshold value indicating a cluster of high weight photons; and

displaying a rectangle on a photon emission image of the photon emission data around an area substantially corresponding to the two spatial dimensions of the three-dimensional range if the number of high weight photons within the three-dimensional range exceeds the second threshold value,

wherein the photons having a weight above the first threshold value are likely to have originated from the transistor photon emission, and

wherein the cluster of high weight photons is likely to correspond to transistor area of the transistor generating the transistor photon emission.

14. A method for discriminating between photons emitted from a transistor and photons emitted from background sources, the method comprising:

detecting emissions data of a plurality of photons to obtain collected photon emission data, the collected photon emission data of each photon having a spatial component corresponding with a detection location of the photon and a temporal component corresponding with a detection time of the photon,

spatially correlating the collected photon emission data of a photon from among the plurality of photons with the collected photon emission data of some or all of the plurality of photons to obtain spatially correlated photon emission data for the photon;

temporally correlating the collected photon emission data of the photon with the collected photon emission data of some or all of the plurality of photons to obtain temporally correlated photon emission data for the photon;

assigning a weight to the photon as a function of the spatially correlated photon emission data of the photon and the temporally correlated photon emission data of the photon; and

determining from the weight of the photon a likelihood that the photon was emitted from the transistor.

15. The method of claim 14,

wherein the plurality of photons are grouped into overlapping time bins, and

wherein the temporally correlating the collected photon emission data of the photon includes temporally correlating the collected photon emission data of the photon with the collected photon emission data of a group of photons falling in a same time bin as the photon.

16. The method of claim 14, wherein the determining from the weight of the photon a likelihood that the photon was emitted from the transistor includes determining if the weight of the photon is above a threshold value corresponding to a background photon emission level.

17. The method of claim 14, further comprising:

determining first photons detected within a spatial range about a selected photon and second photons detected within a temporal range about the selected photon,

wherein the spatially correlating the collected photon emission data includes;

correlating the spatial component corresponding to the selected photon with the spatial components corresponding to the first photons to obtain the spatially correlated photon emission data for the selected photon, and

wherein the temporally correlating the collected photon emission data includes;

correlating the temporal component corresponding to the selected photon with the temporal components corresponding to the second photons to obtain the temporally correlated photon emission data for the selected photon.

18. The method of claim 17, wherein the weight is selected from a group consisting of:

a sum of a spatial weight obtained from the spatially correlated photon emission data of the selected photon and a temporal weight obtained from the temporally correlated photon emission data of the selected photon,

the greater of a spatial weight obtained from the spatially correlated photon emission data of the selected photon and a temporal weight obtained from the temporally correlated photon emission data of the selected photon, and

a lesser of a spatial weight obtained from the spatially correlated photon emission data of the selected photon and a temporal weight obtained from the temporally correlated photon emission data of the selected photon.

19. The method of claim 17, wherein the spatial weight is the number of photons detected within the spatial range of the selected photon.

20. The method of claim 17, wherein the temporal weight is the number of photons detected within the temporal range of the selected photon.