Alignment sensor
View Patent ↗The present invention relates in general to detection of an alignment mark on a workpiece. More particularly, interferometry is applied to detect alignment signals from the surface of a workpiece such as a wafer or reticle. Other aspects of the present invention are reflected in the detailed description, figures and claims.
1. A method of detecting an alignment mark on a workpiece, comprising the actions of:
impinging a radiation on a surface of the workpiece, through an interferometer, while scanning the alignment mark;
employing phase modulation to generate complex amplitude information using radiation returned from the surface of the workpiece; and
collecting data corresponding to the complex amplitude information for the scanned alignment mark.
2. The method according to claim 1 , further including creating an image of the complex amplitude information across the scanned alignment mark.
3. The method according to claim 1 , wherein the radiation is a broad spectrum light source.
4. The method according to claim 3 , wherein at least one colored filter is applied to the radiation.
5. The method according to claim 3 , wherein at least one spatial filter is applied to the radiation.
6. The method according to claim 3 , wherein at least one polarizing filter is applied to the radiation.
7. The method according to claim 1 , further including varying the radiation at least once during the impinging of the radiation.
8. The method according to claim 7 , wherein at least one colored filter is applied to the radiation.
9. The method according to claim 7 , wherein at least one spatial filter is applied to the radiation.
10. The method according to claim 7 , wherein at least one polarizing filter is applied to the radiation.
11. The method of claim 1 , further including aligning the workpiece utilizing the data.
12. The method of claim 11 , further including forming patterns in resist on the workpiece after aligning the workpiece.
13. The method of claim 11 , further including forming patterns in resist on the workpiece after aligning the workpiece, selectively removing the resist, and forming structures in the workpiece through the selectively removed resist.
14. A method of detecting an alignment mark on a workpiece, comprising the actions of:
impinging a radiation on the surface of the workpiece, through an interferometer, while scanning the alignment mark;
collecting at least complex amplitude data corresponding to radiation returned from the surface of the workpiece;
aligning said workpiece utilizing said data; and
exposing a resist layer on said workpiece utilizing said alignment.
15. The method according to claim 14 , wherein at least one colored filter is applied to the radiation.
16. The method according to claim 14 , wherein a plurality of wavelengths are used for the radiation.
17. The method according to claim 14 , wherein at least one spatial filter is applied to the radiation.
18. The method according to claim 14 , wherein at least one polarizing filter is applied to the radiation.
19. The method of claim 14 , further including forming patterns in resist on the workpiece after aligning the workpiece, selectively removing the resist, and forming structures in the workpiece through the selectively removed resist.