Multiple directional scans of test structures on semiconductor integrated circuits

• US 6,566,885 B1
• Filed: 08/25/2000
• Issued: 05/20/2003
• Est. Priority Date: 12/14/1999
• Status: Expired due to Term

• Current Assignee: KLA-Tencor Corporation
• Original Assignee: KLA-Tencor Corporation
• Inventors: Leslie, Brian C., Walker, David J., Pinto, Gustavo A., Long, Robert Thomas, Satya, Akella V. S., Adler, David L.
• Primary Examiner(s): Oda, Christine K.
• Application Number:
  US09/648,109
• Time in Patent Office: 998 Days
• Field of Search: 324/752, 324/501, 250/310, 356/237.2, 356/237.3
• US Class Current: 324/501
• CPC Class Codes: G01N 21/66 electrically excited, e.g. electroluminescence
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 23/04 and forming images of the material
• CPC Class Codes: G01R 31/2884 using dedicated test connectors, test elements or test circuits on the IC under test G01R31/2855 takes precedence
• CPC Class Codes: G01R 31/307 of integrated circuits
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01L 22/34 Circuits for electrically characterising or monitoring manufacturing processes, e. g. whole test die, wafers filled with test structures, on-board-devices incorporated on each die, process control monitors or pad structures thereof, devices in scribe line switching, multiplexing, gating devices G01R19/25; process control with lithography, e.g. dose control, G03F7/20; structures for alignment control by optical means G03F7/70633
• CPC Class Codes: Y10S 977/849 with scanning probe

Abstract

A sample is inspected. The sample is scanned in a first direction with at least one particle beam. The sample is scanned in a second direction with at least one particle beam. The second direction is at an angle to the first direction. The number of defects per an area of the sample are found as a result of the first scan, and the position of one or more of the found defects is determined from the second scan. In a specific embodiment, the sample includes a test structure having a plurality of test elements thereon. A first portion of the test elements is exposed to the beam during the first scan to identify test elements having defects, and a second portion of the test elements is exposed during the second scan to isolate and characterize the defect.

Claims

1. A method of inspecting a sample, comprising:

a in a first direction, scanning a first portion of the sample with an incident charged particle beam and detecting a portion of charged particles emitted from the sample in response to the incident charged particle beam;

b in a second direction, scanning a second portion of the sample with an incident charged particle beam and detecting a portion of charged particles emitted from the sample in response to the incident charged particle beam, the second direction being at an angle to the first direction,

wherein a general location of a defect within the second portion is determined from the first direction scan, and

wherein a specific location of the defect within the second portion is determined from the second direction scan,

wherein the general location of the defect found during the first direction scan has a different periodicity than the specific location of the defect found during the second direction scan.

2. A method as recited in claim 1, wherein the first direction is orthogonal to the second direction.

3. A method as recited in claim 1, wherein the first and second portions of the sample overlap.

4. A method as recited in claim 3 wherein the second portion contains the first portion.

5. A method of inspecting a sample, comprising:

a. in a first direction, scanning a first portion of the sample with at least one particle beam;

b. in a second direction, scanning a second portion of the sample with at least one particle beam, the second direction being at an angle to the first direction,

wherein a general location of a defect within the second portion is determined from the first direction scan,

wherein a specific location of the defect within the second portion is determined from the second direction scan, and

wherein the specific location of the defect is found by performing a binary search in the second direction.

6. A method of inspecting a sample, comprising:

a. in a first direction, scanning a first portion of the sample with at least one particle beam;

b. in a second direction, scanning a second portion of the sample with at least one particle beam, the second direction being at an angle to the first direction,

wherein a general location of a defect within the second portion is determined from the first direction scan,

wherein a specific location of the defect within the second portion is determined from the second direction scan, and

wherein the defect is a short between a first conductive portion and a second conductive portion and the specific location of the defect is found by scanning between the first and second conductive portions to determine a location of a change in intensity level, the change in intensity level indicating the specific location of the defect.

7. A method of inspecting a sample, comprising:

a. in a first direction, scanning a first portion of the sample with an incident electron beam and detecting a portion of secondary and/or backscattered electrons emitted from the sample in response to the incident electron beam;

b. in a second direction, scanning a second portion of the sample with an incident electron beam and detecting a portion of secondary and/or backscattered electrons emitted from the sample in response to the incident electron beam, the second direction being at an angle to the first direction,

wherein an inventory of defects within the second portion is determined from the first, direction scan, and

wherein a characterization of defects within the second portion is determined from the second direction scan.

8. The method as recited in claim 7 wherein the second portion contains the first portion.

9. A method as recited in claim 7, wherein the second direction scan is performed in an array mode.

10. A method as recited in claim 7, wherein the inventory of defects comprises a number of defects per an area of the sample and the characterization of defects comprises a position of one or more found defects.

11. The method of claim 7, wherein the same incident electron beam is used to perform both the scan in the first direction and the scan in the second direction.

12. The method of claim 7, wherein the relative motion in at least one of the scan in the first direction and the scan in the second direction is provided by moving a stage carrying the sample.

13. The method of claim 7, wherein the incident electron beam travels through a column and the relative motion in at least one of the scan in the first direction and the scan in the second direction is provided by moving the column with respect to the sample.

14. The method of claim 7, wherein the relative motion between the at least one of the first direction and the scan in the second direction is provided by deflecting the incident electron beam.

15. The method of claim 7, wherein the sample is moved relative to the incident electron beam during the first scan at a substantially constant velocity.

16. The method of claim 7, wherein the first direction and the second direction are substantially orthogonal to one another.

17. The method of claim 7, wherein the sample includes a test structure having a plurality of test elements thereon, and wherein a first portion of the test elements is exposed to the incident electron beam during the first scan to identify test elements having defects, and a second portion of the test elements are exposed to the incident electron beam during the second scan to isolate and characterize the defect.

18. The method of claim 17, wherein the first portion and second portion at least partially overlap.

19. The method of claim 17, wherein the first portion and the second portion are not entirely coextensive.

20. The method of claim 17, wherein defects present in the test elements are located as a result of exposing the test elements in the second direction.

21. The method of claim 17, wherein the test elements are elongated along a line substantially parallel to the second direction.

22. The method of claim 7, wherein the scan in the first direction and the scan in the second direction are performed in a vacuum and the method further comprising without breaking the vacuum, utilizing a focused ion beam to remove structure from the sample to uncover and characterize the defect.

23. The method of claim 7, wherein the second portion is charged during the scan of the first portion in the first direction and the characterization of the defects within the second portion is based on a signal level at an end of the second portion which forms part of the first portion.

24. The method of claim 23, wherein the characterization of defects includes a location of a defect within the second portion.