Scanner overlay correction system and method
View Patent ↗A method includes performing a semiconductor fabrication process on a plurality of substrates. The plurality of substrates are divided into a first subset and a second subset. A rework process is performed on the second subset of the plurality of substrates but not on the first subset. A respective mean value of at least one exposure parameter for a lithography process is computed for each respective one of the first and second subsets of the plurality of substrates. A scanner overlay correction and a mean correction are applied to expose a second plurality of substrates on which the rework process has been performed. The mean correction is based on the computed mean values.
1. A control apparatus comprising:
a controller configured to determine whether a semiconductor substrate to be exposed by a scanner has been subjected to a rework process; and
a non-transitory, machine readable storage medium containing a mean correction value to be applied to the scanner for exposing the semiconductor substrate if the semiconductor substrate has been subjected to the rework process, wherein:
the controller is configured to control the scanner using a scanner overlay correction, and
the controller is further configured to apply the mean correction value to adjust an exposure parameter of the scanner if the semiconductor substrate to be exposed by the scanner has been subjected to the rework process.
2. The apparatus of claim 1 , wherein the controller is configured to control the scanner to expose substrates, on which the rework process has not been performed, without using the mean correction.
3. The apparatus of claim 1 , wherein the controller is configured to compute the mean correction as a difference between:
a mean of the exposure parameter among a first plurality of substrates that have been processed by the semiconductor fabrication process and the rework process, and
a mean of the exposure parameter among a second plurality of substrates that have been processed by the semiconductor fabrication process but not the rework process.
4. The apparatus of claim 3 , wherein the exposure parameter includes:
a first wafer scaling coefficient for a first direction; and
a second wafer scaling coefficient for a second direction orthogonal to the first direction.
5. The apparatus of claim 1 , wherein the semiconductor fabrication process is a chemical mechanical polishing (CMP) process performed on a layer of one of the first plurality of substrates, and the rework process is a CMP rework process performed on the same layer of the one substrate.
6. The apparatus of claim 1 , wherein the exposure parameter is one of the group consisting of wafer rotation, wafer non-orthogonality and wafer scaling coefficients.
7. The apparatus of claim 1 , wherein the controller contains an overlay advanced process control model corresponding to the scanner, the model including an adjustment for wafer rotation, an adjustment for wafer non-orthogonality and an adjustment for wafer scaling coefficients.
8. The apparatus of claim 1 , wherein:
the controller is configured to compute the mean correction as a difference between:
a mean of the exposure parameter among a first plurality of substrates that have been processed by the semiconductor fabrication process and the rework process, and
a mean of the exposure parameter among a second plurality of substrates that have been processed by the semiconductor fabrication process but not the rework process;
the controller is configured to control the scanner to expose substrates, on which the rework process has not been performed, without using the mean correction;
the exposure parameter includes:
a first wafer scaling coefficient for a first direction; and
a second wafer scaling coefficient for a second direction orthogonal to the first direction;
the semiconductor fabrication process is a chemical mechanical polishing (CMP) process performed on a layer of one of the first plurality of substrates, and the rework process is a CMP rework process performed on the same layer of the one substrate; and
the controller contains an overlay advanced process control model corresponding to the scanner, the model including an adjustment for wafer rotation, an adjustment for wafer non-orthogonality and an adjustment for wafer scaling coefficients.
9. The apparatus of claim 1 , wherein the semiconductor fabrication process is a photo process performed on a layer of one of the first plurality of substrates, and the rework process is a photo rework process performed on the same layer of the one substrate.
10. A control apparatus comprising:
a controller configured to determine whether a semiconductor substrate to be exposed by a scanner has been subjected to a first set of fabrication processes; and
a non-transitory, machine readable storage medium containing a mean correction value to be applied to the scanner for exposing the semiconductor substrate if the semiconductor substrate has been subjected to a second set of fabrication processes different from the first set of fabrication processes, wherein:
the controller is configured to control the scanner using a scanner overlay correction, wherein:
the controller is further configured to apply the mean correction value to adjust an exposure parameter of the scanner if the semiconductor substrate to be exposed by the scanner has been subjected to the second set of fabrication processes, and
the controller is configured to control the scanner to expose substrates subjected to the first set of fabrication processes, without using the mean correction.
11. The apparatus of claim 10 , wherein the controller is configured to compute the mean correction as a difference between:
a mean of the exposure parameter among a first plurality of substrates that have been processed by the second set of fabrication processes, and
a mean of the exposure parameter among a second plurality of substrates that have been processed by the first set of fabrication processes.
12. The apparatus of claim 11 , wherein the exposure parameter includes:
a first wafer scaling coefficient for a first direction; and
a second wafer scaling coefficient for a second direction orthogonal to the first direction.
13. The apparatus of claim 10 , wherein the second set of fabrication processes includes a chemical mechanical polishing (CMP) process performed on a layer of one of the first plurality of substrates, and a CMP rework process performed on the same layer of the one substrate.
14. The apparatus of claim 10 , wherein the exposure parameter includes:
a first wafer scaling coefficient for a first direction; and
a second wafer scaling coefficient for a second direction orthogonal to the first direction.
15. The apparatus of claim 10 , wherein the exposure parameter is one of the group consisting of wafer rotation, wafer non-orthogonality and wafer scaling coefficients.
16. The apparatus of claim 10 , wherein the controller contains an overlay advanced process control model corresponding to the scanner, the model including an adjustment for wafer rotation, an adjustment for wafer non-orthogonality and an adjustment for wafer scaling coefficients.
17. Apparatus comprising:
a scanner; and
a controller for controlling operation of the scanner, the controller configured to determine whether a semiconductor substrate to be exposed by the scanner has been subjected to a rework process; and
a non-transitory, machine readable storage medium containing a mean correction value to be applied to the scanner for exposing the semiconductor substrate if the semiconductor substrate has been subjected to the rework process, wherein:
the controller is configured to control the scanner using a scanner overlay correction, and
the controller is further configured to apply the mean correction value to adjust an exposure parameter of the scanner if the semiconductor substrate to be exposed by the scanner has been subjected to the rework process.
18. The apparatus of claim 17 , wherein the controller is configured to compute the mean correction as a difference between:
a mean of the exposure parameter among a first plurality of substrates that have been processed by the semiconductor fabrication process and the rework process, and
a mean of the exposure parameter among a second plurality of substrates that have been processed by the semiconductor fabrication process but not the rework process.
19. The apparatus of claim 18 , wherein the exposure parameter includes:
a first wafer scaling coefficient for a first direction; and
a second wafer scaling coefficient for a second direction orthogonal to the first direction.
20. The apparatus of claim 17 , wherein the exposure parameter is one of the group consisting of wafer rotation, wafer non-orthogonality and wafer scaling coefficients.