Characterization of asymmetric material deposition for metrology
View Patent ↗A method of characterizing asymmetric depositions on a target is provided. The method includes forming at least four asymmetrical petals in a layer on a substrate, and depositing a light-absorbing material on the at least four asymmetrical petals, wherein the light-absorbing material deposits unevenly on a plurality of walls of the at least four asymmetrical petals. The method further includes determining a pattern shift response (PSR) from the light-absorbing material on each of the walls of the at least four asymmetrical petals, and converting the pattern shift response (PSR) to an asymmetry of thicknesses of the light-absorbing material deposited on facing walls of the at least four asymmetrical petals. The method further includes correcting an overlay petal position based on the asymmetry of thicknesses.
1. A method of characterizing asymmetric depositions on a target, comprising:
forming at least four asymmetrical petals in a layer on a substrate;
depositing a light-absorbing material on the at least four asymmetrical petals, wherein the light-absorbing material deposits unevenly on a plurality of walls of the at least four asymmetrical petals;
determining a pattern shift response (PSR) from the light-absorbing material on each of the walls of the at least four asymmetrical petals;
converting the pattern shift response (PSR) to an asymmetry of thicknesses of the light-absorbing material deposited on facing walls of the at least four asymmetrical petals; and
correcting an overlay petal position based on the asymmetry of thicknesses.
2. The method of claim 1 , wherein the at least four asymmetrical petals include two pairs of two comb-shaped petals, wherein each comb-shaped petal has a symmetrical portion and a plurality of arms extending from the symmetrical portion.
3. The method of claim 1 , wherein the at least four asymmetrical petals include two pairs of a vertical series of parallel line having the same pitch, but a decreasing line width, with one pair rotated 90 degrees from the other pair.
4. The method of claim 1 , wherein the at least four asymmetrical petals include two pairs of a vertical series of tapered (dagger-like) lines having deceasing line widths, but the same pitch, with one pair rotated 90 degrees from the other pair.
5. The method of claim 1 , wherein the at least four asymmetrical petals include two pairs of a solid block with parallel lines having decreasing line widths with one pair rotated 90 degrees from the other pair.
6. The method of claim 1 , wherein the at least four asymmetrical petals include two pairs of a solid block and a staggered array of squares/rectangles with one pair rotated 90 degrees from the other pair.
7. The method of claim 1 , wherein the at least four asymmetrical petals include two pairs of two asymmetrical petals, wherein the two asymmetrical petals of each pair form a mirror image.
8. The method of claim 7 , wherein there are four asymmetrical petals per die on a wafer.
9. The method of claim 8 , further comprising an overlay petal adjacent to the at least four asymmetrical petals.
10. The method of claim 9 , wherein the at least four asymmetrical petals include a first set of four adjacent asymmetrical petals adjacent to a second set of four adjacent asymmetrical petals.
11. A method of characterizing asymmetric depositions on a target, comprising:
forming at least four asymmetrical petals in a layer on a substrate, wherein the at least four asymmetrical petals include two pairs of two asymmetrical petals, wherein the two asymmetrical petals of each pair form a mirror image, and wherein a third pair of asymmetrical petals has a different duty cycle than the first two pairs;
depositing a light-absorbing material on the at least four asymmetrical petals, wherein the light-absorbing material deposits unevenly on a plurality of walls of the at least four asymmetrical petals;
determining a pattern shift response (PSR) from the light-absorbing material on each of the walls of the at least four asymmetrical petals;
converting the pattern shift response (PSR) to an asymmetry of thicknesses of the light-absorbing material deposited on facing walls of the at least four asymmetrical petals; and
correcting an overlay petal position based on the asymmetry of thicknesses.
12. The method of claim 11 , wherein the at least four asymmetrical petals include a first set of four adjacent asymmetrical petals adjacent to a second set of four adjacent asymmetrical petals.
13. The method of claim 11 , wherein the at least four asymmetrical petals include two pairs of a solid block with parallel lines having decreasing line widths with one pair rotated 90 degrees from the other pair.
14. The method of claim 11 , wherein each of the at least four asymmetrical petals forms a triple aim target.