Process control using process data and yield data
View Patent ↗A method for monitoring a manufacturing process features acquiring metrology data for semiconductor wafers at the conclusion of a final process step for the manufacturing process (“Step a”). Data is acquired for a plurality of process variables for a first process step for manufacturing semiconductor wafers (“Step b”). A first mathematical model of the first process step is created based on the metrology data and the acquired data for the plurality of process variables for the first process step (“Step c”). Steps b and c are repeated for at least a second process step for manufacturing the semiconductor wafers (“Step d”). An nth mathematical model is created based on the metrology data and the data for the plurality of process variables for each of the n process steps (“Step e”). A top level mathematical model is created based on the metrology data and the models created by steps c, d and e (“Step f”). The top level mathematical model of Step f is based on those process variables that have a substantial effect on the metrology data.
1. A method for monitoring a manufacturing process, comprising:
a. acquiring metrology data for semiconductor wafers at the conclusion of a final process step for the manufacturing process;
b. acquiring data for a plurality of process variables for a first process step for manufacturing semiconductor wafers;
c. creating a first mathematical model of the first process step based on the metrology data and the acquired data for the plurality of process variables for the first process step;
d. repeating step b. and step c. for at least a second process step for manufacturing the semiconductor wafers;
e. creating an n th mathematical model based on the metrology data and the data for the plurality of process variables for each of the n process steps; and
f. creating a top level mathematical model based on the metrology data and the models created by steps c., d. and e., the top level mathematical model being based on those process variables that have a substantial effect on the metrology data.
2. The method of claim 1 , comprising comparing data for the first process step for manufacturing a semiconductor wafer to the top level model of step f. to determine whether a fault occurred during the first process step.
3. The method of claim 2 , comprising comparing data for the second process step for manufacturing a semiconductor wafer to the top level model of step f. to determine whether a fault occurred during the second process step.
4. The method of claim 1 , comprising comparing data for each process step for manufacturing a semiconductor wafer to the top level model of step f. to determine whether a fault occurred during any of the n process steps.
5. The method of claim 1 , comprising comparing data for the first process step for manufacturing a semiconductor wafer to the top level model of step f. to determine whether manufacturing yield will be above a predetermined limit.
6. The method of claim 1 , wherein the mathematical model of step c. is created using a multivariate analysis technique.
7. The method of claim 1 , wherein the mathematical models of the n process steps are partial least squares models.
8. The method of claim 7 , wherein creating the top level model comprises combining scores for the partial least squares models of the n process steps and the mathematical model of the metrology data.
9. The method of claim 7 , comprising comparing data for at least one of the n process steps for subsequent manufacturing runs to the top level model of step f. to generate a prediction of yield for the manufacturing process.
10. The method of claim 1 , wherein the metrology data comprises yield measurements from semiconductor wafers produced by one or more manufacturing runs.
11. The method of claim 7 , comprising comparing data for at least one of the n process steps for subsequent manufacturing runs to the top level model of step f. to generate a prediction of the metrology results for the manufacturing process.
12. The method of claim 1 , comprising modifying operating properties of a process step based on whether the top level model determines that a fault has occurred during the process step.
13. The method of claim 1 , comprising updating the mathematical model of at least one of the n process steps by adjusting a weighting in the mathematical model associated with the plurality of process variables based on which variables are determined to contribute more significantly to a fault occurring during at least one of the n process steps.
14. The method of claim 1 , wherein process variables that have a substantial effect on the metrology data are weighted more in creating the top level mathematical model than process variables that do not have a substantial effect on the metrology data.
15. The method of claim 1 , wherein the models created by steps c., d. and e. comprise process information and noise information.
16. The method of claim 1 , wherein the top level mathematical model comprises process variables that affect yield of the manufacturing process.