Calibration method for a lithographic apparatus
A first substrate 2002 has a calibration pattern applied to a first plurality of fields 2004 by a lithographic apparatus. Further substrates 2006, 2010 have calibration patterns applied to further pluralities of fields 2008, 2012 . The different pluralities of fields have different sizes and/or shapes and/or positions. Calibration measurements are performed on the patterned substrates 2002, 2006, 2010 and used to obtain corrections for use in controlling the apparatus when applying product patterns to subsequent substrates. Measurement data representing the performance of the apparatus on fields of two or more different dimensions (fields 2004, 2008, 2012 in this example) is gathered together in a database 2013 and used to synthesize the information needed to calibrate the apparatus for a new size. Calibration data is also obtained for different scan and step directions.
1. A method of determining data associated with a layout of fields on a substrate processed by a lithographic apparatus, the method comprising:
providing measurement data for a plurality of fields being arranged according to a first layout;
providing further measurement data for a further plurality of fields being arranged according to a second layout different from the first layout;
creating a prediction function based on the measurement data and the further measurement data; and
using a third layout as an input for the prediction function to determine data associated with the third layout.
2. The method of claim 1 , further comprising using the determined data to derive correction parameters for use in controlling the lithographic apparatus to apply a pattern to a plurality of fields being arranged according to the third layout on a substrate.
3. The method of claim 2 , further comprising using the prediction function to simulate performance of the lithographic apparatus for a plurality of fields being arranged according to the third layout.
4. The method of claim 2 , wherein the correction parameters include intra-field correction parameters obtained using intra-field components of the measurement data, and/or wherein the correction parameters include inter-field correction parameters obtained using inter-field components of the measurement data.
5. The method of claim 1 , wherein the third layout comprises product fields having a product field dimension different from a field dimension of the plurality of fields and/or the further plurality of fields.
6. The method of claim 5 wherein the plurality of fields and the further plurality of fields include fields having two or more different dimensions.
7. The method of claim 1 , wherein the third layout comprises product fields having a product field dimension the same as a field dimension of some or all of the plurality of fields and the further plurality of fields, with field positions relative to the substrate different from field positions of the plurality of fields and the further plurality of fields.
8. The method of claim 5 , wherein the plurality of fields and the further plurality of fields include fields having the same field dimensions but different field positions relative to the substrate.
9. The method of claim 1 , wherein the lithographic apparatus applies patterns to fields using a scanning motion and wherein each of the measurement data and the further measurement data comprises:
a first measurement data set representing performance in fields to which a calibration pattern was applied using a first scanning direction; and
a second measurement data set representing performance in fields to which the calibration pattern was applied using a second scanning direction.
10. The method of claim 9 , wherein the lithographic apparatus applies patterns to fields using a scanning motion preceded by a stepping motion, and wherein, in each of the measurement data and the further measurement data, each of the first measurement data set and second measurement data set comprises:
a first measurement data subset representing performance in fields to which the calibration pattern was applied following a stepping motion in a first stepping direction; and
a second measurement data subset representing performance in fields to which the calibration pattern was applied following a stepping motion in a second stepping direction.
11. The method of claim 9 , wherein the correction parameters include:
correction parameters specifically for use in applying said pattern using the first scanning direction; and
correction parameters specifically for use in applying said pattern using the second scanning direction.
12. The method of claim 10 , wherein the correction parameters include:
correction parameters specifically for use in applying said pattern using the first scanning direction and the first stepping direction;
correction parameters specifically for use in applying said pattern using the first scanning direction and the second stepping direction;
correction parameters specifically for use in applying said pattern using the second scanning direction and the first stepping direction; and
correction parameters specifically for use in applying said pattern using the second scanning direction and the second stepping direction.
13. The method of claim 9 , wherein providing the measurement data comprises:
applying said calibration pattern sequentially to the at least one substrate using a sequence of scanning and stepping directions; and
performing a measurement on the applied patterns.
14. The method of claim 1 , wherein a calibration pattern has been applied repeatedly to fields on the same substrate while applying a shift between repetitions, to enable measurements to represent separately the performance of the lithographic apparatus in each repetition.
15. A computer-readable recording medium having stored thereon a computer program comprising machine readable instructions which, when run on a suitable processor, cause the processor to perform the creating and using steps of the method of claim 1 .