Method and apparatus for measuring overlay errors using overlay measurement patterns

1. An overlay error measurement structure, comprising:

a lower-layer pattern disposed over a substrate; and

an upper-layer pattern disposed over the lower-layer pattern and at least partially overlapping with the lower-layer pattern, wherein:

the lower-layer pattern comprises a first plurality of first sub-patterns having a first length extending in a first direction and being arranged in an extent having a second length in a second direction crossing the first direction in a first portion of the lower-layer pattern and a second plurality of second sub-patterns having substantially the second length extending in the second direction and being arranged in an extent substantially having the first length in the first direction in a second portion of the lower-layer pattern adjacent to the first portion of the lower-layer pattern,

the upper-layer pattern comprises a third plurality of third sub-patterns having a third length extending in the first direction and being arranged in an extent having a fourth length in the second direction in a first portion of the upper-layer pattern and a fourth plurality of fourth sub-patterns having substantially the fourth length in the second direction and being arranged in an extent having substantially the third length extending in the first direction in a second portion of the upper-layer pattern adjacent to the first portion of the upper-layer pattern, and

a pattern pitch varies along the second direction between each two neighboring sub-patterns within at least one of at least a part of the first plurality of first sub-patterns and at least a part of the third plurality of third sub-patterns and a pattern pitch varies along the first direction between each two neighboring sub-patterns within at least one of at least a part of the second plurality of second sub-patterns and at least a part of the fourth plurality of fourth sub-patterns.

2. The overlay error measurement structure of claim 1 , wherein:

a pattern pitch of the first plurality of first sub-patterns is constant, and

a pattern pitch of the third plurality of third sub-patterns varies along the second direction, and at least a part of the third plurality of third sub-patterns has a different pattern pitch than the first plurality of first sub-patterns.

3. The overlay error measurement structure of claim 1 , wherein:

a pattern pitch of the second plurality of second sub-patterns is constant, and

a pattern pitch of the first plurality of first sub-patterns varies along the second direction, and at least a part of the first plurality of first sub-patterns has a different pattern pitch than the second plurality of second sub-patterns.

4. The overlay error measurement structure of claim 1 , wherein:

the first plurality of first sub-patterns include line-and-space patterns having a constant line width, and

the second plurality of second sub-patterns include line-and-space patterns, and a line width of line patterns of the line-and-space patterns of the second plurality of second sub-patterns varies along the first direction.

5. The overlay error measurement structure of claim 1 , wherein:

the second plurality of second sub-patterns include line-and-space patterns having a constant line width, and

the first plurality of first sub-patterns include line-and-space patterns, and a line width of line patterns of the line-and-space patterns of the first plurality of first sub-patterns varies along the second direction.

6. The overlay error measurement structure of claim 1 , wherein:

at least one of the first plurality of first sub-patterns and the second plurality of second sub-patterns include two or more line-and-space patterns, each one of the two or more line-and-space patterns is arranged in the second direction for the first plurality of first sub-patterns, and is arranged in the first direction for the second plurality of second sub-patterns.

7. The overlay error measurement structure of claim 6 , wherein a length of the line-and-space patterns of the two or more line-and-space patterns varies between the two or more line-and-space patterns.

8. The overlay error measurement structure of claim 6 , wherein a length of the line-and-space patterns of the two or more line-and-space patterns is a same length for the two or more line-and-space patterns.

9. The overlay error measurement structure of claim 1 , wherein a pattern width within at least one of at least a part of the first plurality of first sub-patterns and at least a part of the second plurality of second sub-patterns is a constant.

10. An overlay error measurement structure, comprising:

a lower-layer pattern disposed over a substrate; and

an upper-layer pattern disposed over the lower-layer pattern and at least partially overlapping with the lower-layer pattern, wherein:

the lower-layer pattern comprises first lower sub-patterns having a first length extending in a first direction and being arranged in a second length in a second direction crossing the first direction in a first portion of the lower-layer pattern and second lower sub-patterns having substantially the second length extending in the second direction and being arranged in substantially the first length in the first direction in a second portion of the lower-layer pattern adjacent to the first portion of the lower-layer pattern,

the upper-layer pattern comprises third upper sub-patterns having a third length extending in the first direction and being arranged in a fourth length in the second direction in a first portion of the upper-layer pattern and fourth upper sub-patterns having substantially the fourth length extending in the second direction and being arranged in substantially the third length in the first direction in a second portion of the upper-layer pattern adjacent to the first portion of the lower-layer pattern, and

a pattern pitch varies along the first direction between each two neighboring sub-patterns of at least one of a part of the second lower sub-patterns and at least a part of the fourth upper sub-patterns and a pattern pitch varies along the second direction between each two neighboring sub-patterns of at least one of a part of the first lower sub-patterns and at least a part of the third upper sub-patterns and a pattern width of one of at least a part of the first lower sub-patterns and at least a part of the third upper sub-patterns is a constant along the second direction.

11. The overlay error measurement structure of claim 10 , wherein the pattern pitch of the first lower sub-patterns and the pattern width of the second lower sub-patterns are constants.

12. The overlay error measurement structure of claim 10 , wherein the pattern pitch of the third upper sub-patterns and the pattern width of the fourth upper sub-patterns are constants.

13. The overlay error measurement structure of claim 10 , wherein the first lower sub-patterns and the second lower sub-patterns are disposed adjacent to each other along the second direction, and wherein the third upper sub-patterns and the fourth upper sub-patterns are disposed adjacent to each other along the second direction.

14. An overlay error measurement structure, comprising:

a lower-layer pattern disposed over a substrate; and

an upper-layer pattern disposed over the lower-layer pattern and at least partially overlapping with the lower-layer pattern, wherein:

the lower-layer pattern comprises a first plurality of first sub-patterns having a first length extending in a first direction and being arranged in an extent having a second length in a second direction crossing the first direction in a first portion of the lower-layer pattern and a second plurality of second sub-patterns having substantially the second length extending in the second direction and being arranged in an extent substantially having the first length in the first direction in a second portion of the lower-layer pattern adjacent to the first portion of the lower-layer pattern,

the upper-layer pattern comprises a third plurality of third sub-patterns having a third length extending in the first direction and being arranged in an extent having a fourth length in the second direction in a first portion of the upper-layer pattern and a fourth plurality of fourth sub-patterns having substantially the fourth length in the second direction and being arranged in an extent having substantially the third length extending in the first direction in a second portion of the upper-layer pattern adjacent to the first portion of the upper-layer pattern,

a pattern pitch varies along the second direction between each two neighboring sub-patterns within at least one of at least a part of the first plurality of first sub-patterns and at least a part of the third plurality of third sub-patterns and a pattern pitch varies along the first direction between each two neighboring sub-patterns within at least one of at least a part of the second plurality of second sub-patterns and at least a part of the fourth plurality of fourth sub-patterns;

the lower-layer pattern further comprises a fifth plurality of first sub-patterns extending in the first direction and being arranged in the second direction and being substantially diagonally symmetric with the first plurality of first sub-patterns in a third portion of the lower-layer pattern; and

the upper-layer pattern further comprises a sixth plurality of third sub-patterns extending in the first direction and being arranged in the second direction and being substantially diagonally symmetric with the third plurality of third sub-patterns in a third portion of the upper-layer pattern, wherein:

the third plurality of third sub-patterns of the upper-layer pattern is shifted in the second direction by an amount of D+OV with respect to the first plurality of first sub-patterns of the lower-layer pattern,

the sixth plurality of third sub-patterns of the upper-layer pattern is shifted in the second direction by an amount of −D+OV with respect to the fifth plurality of first sub-patterns of the lower-layer pattern, and

D is a predetermined design value and OV is an overlay error between the lower-layer pattern and the upper-layer pattern along the second direction.

15. The overlay error measurement structure of claim 14 , wherein the second sub-patterns are substantially perpendicular to the first sub-patterns and the fourth sub-patterns are substantially perpendicular to the third sub-patterns.

16. The overlay error measurement structure of claim 14 , wherein:

a center of gravity of the third plurality of third sub-patterns of the upper-layer pattern is shifted in the second direction by an amount of D+OV with respect to a center of gravity of the first plurality of first sub-patterns of the lower-layer pattern, and

a center of gravity of the sixth plurality of third sub-patterns of the upper-layer pattern is shifted in the second direction by an amount of −D+OV with respect to a center of gravity of the fifth plurality of first sub-patterns of the lower-layer pattern.

17. The overlay error measurement structure of claim 14 , wherein a pattern width within at least one of at least a part of the first plurality of first sub-patterns, at least a part of the second plurality of second sub-patterns, and at least a part of the fifth plurality of first sub-patterns is a constant.

18. The overlay error measurement structure of claim 14 , wherein a pattern pitch varies along the second direction between each two neighboring sub-patterns within at least one of at least a part of the fifth plurality of first sub-patterns and at least a part of the sixth plurality of third sub-patterns.

19. The overlay error measurement structure of claim 14 , wherein:

a pattern pitch of the first plurality of first sub-patterns is constant, and

a pattern pitch of the third plurality of third sub-patterns varies along the second direction, and at least a part of the third plurality of third sub-patterns has a different pattern pitch than the first plurality of first sub-patterns.

20. The overlay error measurement structure of claim 14 , wherein the first plurality of first sub-patterns and the second plurality of second sub-patterns are disposed adjacent to each other along the second direction, and wherein the third plurality of third sub-patterns and the fourth plurality of fourth sub-patterns are disposed adjacent to each other along the second direction.