Multiple directional scans of test structures on srmiconductor integrated circuits

• US 20030155927A1
• Filed: 03/13/2003
• Published: 08/21/2003
• Est. Priority Date: 12/14/1999
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation
• Original Assignee: KLA-Tencor Corporation
• Inventors: Walker, David J., Pinto, Gustavo A., Leslie, Brian C., Long, Robert Thomas, Adler, David L., Satya, Akella V.S.
• Granted Patent: US 6,867,606 B2
• Time in Patent Office: Days
• 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

Disclosed is a method of inspecting a sample. 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. determining a general location of a defect based on the detected charged particles from the first direction scan, wherein the general location corresponds to a second portion of the sample which is outside the first direction scan;

c. in a second direction, scanning the 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; and

d. determining a specific location of a defect based on the detected charged particles from the second direction scan, wherein the specific location corresponds to a third portion of the sample which is contained within the second portion of the sample.

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 as recited in claim 1, wherein the general location of the defect found during the first direction scan have a different periodicity than the specific location of the defect found during the second direction scan.

6. A method as recited in claim 1, wherein the sample forms a plurality of conductive lines on a semiconductor sample and the first portion of the first direction scan is contained within each conductive line and the second portion of the second direction scan includes an entire length of a selected one or more of the conductive lines.

7. A method as recited in claim 6, wherein the second portion of the second direction scan includes an single one of the conductive lines.

8. A method as recited in claim 6, wherein the second portion of the second direction scan includes an entire length of a selected one or more of the conductive lines and excludes the first portion of the selected conductive lines.

9. A method as recited in claim 1, wherein the charged particle beam is an electron beam and the detected charged particles are secondary and/or backscattered electrons.

10. A method of inspecting a sample, comprising:

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

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

wherein a number of defects per an area of the sample are found as a result of the first scan and a position of one or more found defects is determined from the second scan when one or more defects are found from the first scan.

11. The method of claim 10, wherein the same particle beam is used to perform both steps a and b.

12. The method of claim 10, wherein the relative motion in at least one of steps a and b is provided by moving a stage carrying the sample.

13. The method of claim 10, wherein the particle beam travels through a column and the relative motion in at least one of steps a and b is provided by moving a column with respect to the sample.

14. The method of claim 10, wherein the relative motion in at least one of steps a and b is provided by deflecting the particle beam.

15. The method of claim 10, wherein the sample is moved relative to the at least one beam during the first scan at a substantially constant velocity.

16. The method of claim 10, wherein the first direction and the second direction are substantially orthogonal to one another.

17. The method of claim 10, 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 beam during the first scan to identify test elements having defects, and a second portion of the test elements are exposed 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. A method as recited in claim 10, wherein the particle beam is an electron beam.