Apparatus for measuring overlay errors

Patent metadata

Field	Value
Publication number	US-9702693-B2
Application number	US-201615136855-A
Country	US
Kind code	B2
Filing date	Apr 22, 2016
Priority date	Aug 30, 2000
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A metrology system for determining overlay is disclosed. The system includes an optical assembly for capturing images of an overlay mark and a computer for analyzing the captured images to determine whether there is an overlay error. The mark comprises first and second regions that each include at least two separately generated working zones, juxtaposed relative to one another, configured to provide overlay information in a first direction, and include a periodic structure having coarsely segmented elements. The mark comprises third and fourth regions that each include at least two separately generated working zones, juxtaposed relative to one another, configured to provide overlay information in a second direction, and include a periodic structure having coarsely segmented elements. Working zones of the first and second regions are diagonally opposed and spatially offset relative to one another, and the working zones of the third and fourth regions are diagonally opposed and spatially offset relative to one another.

First claim

What is claimed is:

1. A metrology system for determining the overlay between at least two separately generated patterns on a single or successive layers of a substrate, the system comprising:
an optical assembly for capturing images of a multidirectional overlay mark comprising:
a first region having at least two separately generated working zones, that are juxtaposed relative to one another, and are configured to provide overlay information in a first direction, and each include a periodic structure comprised of a plurality of coarsely segmented elements positioned therein,
a second region having at least two separately generated working zones, that are juxtaposed relative to one another, and are configured to provide overlay information in the first direction, and each include a periodic structure comprised of a plurality of coarsely segmented elements positioned therein,
a third region having at least two separately generated working zones, that are juxtaposed relative to one another, and are configured to provide overlay information in a second direction that differs from the first direction, and each include a periodic structure comprised of a plurality of coarsely segmented elements positioned therein,
a fourth region having at least two separately generated working zones, that are juxtaposed relative to one another, and are configured to provide overlay information in the second direction, and each include a periodic structure comprised of a plurality of coarsely segmented elements positioned therein,
wherein the working zones of the first and second regions that were generated together are diagonally opposed and spatially offset relative to one another, and
wherein the working zones of the third and fourth regions that were generated together are diagonally opposed and spatially offset relative to one another; and

a computer for analyzing the captured images to determine whether the multidirectional overlay mark has an overlay error.

2. The system as recited in claim 1 , wherein the first and second regions are positioned in an opposed relationship on opposite sides of a first axis of the multidirectional overlay mark and wherein the third and fourth regions are positioned in an opposed relationship on opposite sides of a second axis of the multidirectional overlay mark.

3. The system as recited in claim 2 , wherein the first axis is a horizontal axis and wherein the second axis is a vertical axis.

4. The system as recited in claim 2 , wherein the center of the first and second regions are aligned with one another on the second axis and wherein the center of the third and fourth regions are aligned with one another on the first axis.

5. The system as recited in claim 1 wherein the multidirectional overlay mark is configured for determining the overlay between three separately generated patterns on a single or successive layers of a substrate.

6. The system as recited in claim 1 , wherein the first region is disposed above a horizontal axis of the multidirectional overlay mark, wherein the second region is disposed below the horizontal axis of the multidirectional overlay mark, wherein the third region is disposed to the left of a vertical axis of the multidirectional overlay mark, and wherein the fourth region is disposed to the right of the vertical axis of the multidirectional overlay mark.

7. The system as recited in claim 6 , wherein the separately generated working zones include a first working zone generated via a first process and a second working zone generated via a second process, and wherein the first region includes the first working zone positioned on a first side and the second working zone positioned on a second side, the second region includes the second working zone positioned on the first side and the first working zone positioned on the second side, the third region includes the first working zone positioned on a first side and the second working zone positioned on a second side, and the fourth region includes the second working zone positioned on a first side and the first working zone positioned on a second side.

8. The system as recited in claim 1 , the first and second regions lie crosswise relative to the third and fourth regions.

9. The system as recited in claim 1 , wherein the arrangement of working zones in the first, second, third and fourth regions is rotational symmetric at 0, 90, 180, 270 and 360degrees about the center of the multidirectional overlay mark.

10. The system as recited in claim 9 , wherein the arrangement of working zones between the first and second regions does not have reflection symmetry, and wherein the arrangement of working zones between the third and fourth regions does not have reflection symmetry.

11. The system as recited in claim 1 , wherein each of the four regions includes three separately generated working zones.

12. A metrology system for determining the overlay between at least two separately generated patterns on a single or successive layers of a substrate, the system comprising:
an optical assembly for capturing images of an overlay mark comprising:
a first set of working zones being formed from a first process and having at least two working zones that are diagonally opposed and spatially offset relative to each other, each of the first set of working zones including a periodic structure comprising a plurality of coarsely segmented elements that are each formed from a plurality of finely segmented elements that are evenly divided over the entire coarsely segmented elements of the first set of working zones, and
a second set of working zones being formed from a second process and having at least two working zones that are diagonally opposed and spatially offset relative to each other, each of the second set of working zones including a periodic structure comprising a plurality of coarsely segmented elements that are each formed from a plurality of finely segmented elements that are evenly divided over the entire coarsely segmented elements of the second set of working zones; and

a computer for analyzing the captured images to determine whether the overlay mark has an overlay error.

13. The system of claim 12 , wherein the coarsely segmented elements within each periodic structure have substantially the same size and shape and equal spacings.

14. The system of claim 12 , wherein the finely segmented elements are etched or deposited vias.

15. The system of claim 12 , wherein the finely segmented elements within each of the coarsely segmented elements have substantially the same size and shape and equal spacings.

16. A metrology system for determining the overlay between at least two separately generated patterns on a single or successive layers of a substrate, the system comprising:
an optical assembly for capturing images of a multidirectional overlay mark comprising:
a plurality of first periodic structures formed via a first process and having a first orientation and comprised of a plurality of coarsely segmented elements, wherein the first periodic structures comprise at least two working zones that are diagonally opposed and spatially offset relative to each other;
a plurality of second periodic structures formed via a second process and having the first orientation and comprised of a plurality of coarsely segmented elements, wherein the second periodic structures comprise at least two working zones that are diagonally opposed and spatially offset relative to each other;
a plurality of third periodic structures formed via the first process and having a second orientation and comprised of a plurality of coarsely segme

Assignees

• Kla Tencor Corp

Inventors

• Ghinovker Mark
• Adel Michael
• Mieher Walter D
• Levy Ady
• Wack Dan

Classifications

• H10P72/57

  Mask-wafer alignment · CPC title

• H10P72/50

  for positioning, orientation or alignment · CPC title

• H10W46/00

  Marks applied to devices, e.g. for alignment or identification · CPC title

• Y10S438/975

  Substrate or mask aligning feature · CPC title

• H01L23/544

  Electricity · mapped topic