System for aligning patterns on a substrate
A system for aligning a first and second pattern based on alignment structures is disclosed. The system comprises a first substrate including the first alignment structure. The alignment structure has a different magnitude of the electrical characteristic than the substrate. The system also includes an electrical probe and a controller for controlling the relative position of the probe with respect to the substrate to measure the electrical characteristic at a plurality of positions proximate the substrate. The measured electrical characteristics are used to identify the location of the alignment structure by identifying a difference between the measured electrical characteristic at pairs of the plurality of positions. A controller identifies the location of a second alignment structure formed on a second substrate. A registration mechanism aligns the two substrates using the identified locations of the first and second alignment structures.
1. A system for aligning a second pattern to a first pattern based on a first alignment structure having a location identified by measurements of an electrical characteristic, comprising:
a first substrate having the first pattern including the first alignment structure, wherein the first alignment structure has a different magnitude of the electrical characteristic than the first substrate;
an electrical probe;
a controller for controlling the relative position of the electrical probe with respect to the first substrate to measure the electrical characteristic corresponding to each of a plurality of positions at or near the first alignment structure, for comparing the measured electrical characteristic as a function of position of the electrical probe to identify the location of the first alignment structure by identifying a difference between the measured electrical characteristic at a pair of the plurality of positions exceeding a predetermined threshold;
a second substrate having the second pattern including a second alignment structure formed thereon;
a controller for identifying the location of the second alignment structure; and
a registration mechanism for aligning the second substrate to the first substrate using the identified locations of the first and second alignment structures.
2. The system of claim 1 , further including a support for the first substrate that includes a hold-down mechanism for the first substrate.
3. The system of claim 1 , further including a first mover for moving the electrical probe along a first direction that is parallel to the first substrate.
4. The system of claim 3 , wherein the controller is configured to control the electrical probe to take a first measurement at a first position, move the electrical probe to a second position that is a first distance along the first direction, and take a second measurement at the second position.
5. The system of claim 4 , wherein the controller is configured to control the electrical probe to move the electrical probe to a third position that is a second distance along the first direction and take a third measurement at the third position, wherein the second distance is less than the first distance if the second measurement corresponds to a proximity of the first alignment structure.
6. The system of claim 4 , wherein the controller is configured to control the electrical probe to move the electrical probe to a third position that is a second distance along a direction opposite the first direction and take a third measurement at the third position, wherein second distance is less than the first distance.
7. The system of claim 3 , further including a second mover for moving the electrical probe along a second direction that is parallel to the first substrate and not parallel to the first direction.
8. The system of claim 3 , further including a third mover for moving the electrical probe along a third direction that is perpendicular to the first substrate to move the electrical probe into and out of contact with the first substrate.
9. The system of claim 1 , wherein the electrical probe is a resistance probe.
10. The system of claim 1 , wherein the electrical probe is a capacitance probe.
11. The system of claim 1 , further including a second electrical probe for measuring the electrical characteristic.
12. The system of claim 1 , further including a first mover for moving the first substrate along a first direction that is parallel to the first substrate.
13. The system of claim 12 , further including a second mover for moving the first substrate along a second direction that is parallel to the first substrate and not parallel to the first direction.
14. The system of claim 1 , wherein the registration mechanism further includes a marking station for providing at least one reference mark on the substrate at a distance and direction determined by the controller, from the identified location of the first alignment structure.
15. The system of claim 14 , wherein the marking station includes at least one of an ink marker, a laser, a blade a drill, a heated tip, an indenter or a hole punch.
16. The system of claim 1 , wherein the registration mechanism further includes a positioner for positioning the second substrate relative to the first substrate so that the second pattern is aligned with the first pattern relative to the first and second alignment structures on the first and second substrates respectively.