Lithographic projection apparatus and device manufacturing method using such lithographic projection apparatus
First Claim
1. Lithographic projection apparatus comprising:
- a radiation system for providing a projection beam of radiation;
a support structure for supporting a patterning device for imparting a pattern to the projection beam;
a substrate table for holding a substrate;
a projection system for projecting the patterned beam onto a target portion of the substrate so as to produce an image of the patterning means on the target portion;
a measurement system for measuring changes in projection system aberrations with time;
a predictive control system for predicting variation of projection system aberrations with time on the basis of model parameters and for generating a control signal for compensating a time-varying property of the apparatus;
an inline model identification system for estimating model parameter errors on the basis of projection system aberration values provided by the predictive control system and measured projection system aberration values provided by the measurement system; and
an updating system utilising the model parameter errors for updating the model parameters of the predictive control system in order to maintain the time-varying property within acceptable performance criteria.
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Abstract
A lithographic projection apparatus includes a measurement system for measuring changes in projection system aberrations with time, and a predictive control system for predicting variation of projection system aberrations with time on the basis of model parameters and for generating a control signal for compensating a time-varying property of the apparatus, such as the OVL values (X-Y adjustment) and the FOC values (Z adjustment) of a lens of the projection system for example. An inline model identification system is provided for estimating model parameter errors on the basis of projection system aberration values provided by the predictive control system and measured projection system aberration values provided by the measurement system, and an updating system utilizes the model parameter errors for updating the model parameters of the predictive control system in order to maintain the time-varying property within acceptable performance criteria.
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Citations
16 Claims
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1. Lithographic projection apparatus comprising:
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a radiation system for providing a projection beam of radiation;
a support structure for supporting a patterning device for imparting a pattern to the projection beam;
a substrate table for holding a substrate;
a projection system for projecting the patterned beam onto a target portion of the substrate so as to produce an image of the patterning means on the target portion;
a measurement system for measuring changes in projection system aberrations with time;
a predictive control system for predicting variation of projection system aberrations with time on the basis of model parameters and for generating a control signal for compensating a time-varying property of the apparatus;
an inline model identification system for estimating model parameter errors on the basis of projection system aberration values provided by the predictive control system and measured projection system aberration values provided by the measurement system; and
an updating system utilising the model parameter errors for updating the model parameters of the predictive control system in order to maintain the time-varying property within acceptable performance criteria. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. Lithographic projection apparatus comprising:
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a radiation system for providing a projection beam of radiation;
a support structure for supporting a patterning device for imparting a pattern to the projection beam;
a substrate table for holding a substrate;
a projection system for projecting the patterned beam onto a target portion of the substrate so as to produce an image of the patterning device on the target portion;
a measurement system for measuring changes in projection system aberrations with time;
a predictive control system for predicting variation of projection system aberrations with time on the basis of model parameters and for generating a control signal for compensating a time-varying property of the apparatus; and
a measurement timing system for controlling measurements by the measurement system such that a time interval between measurements is increased if the control signal decreases below a first threshold value, and the time interval between measurements is decreased if the control signal increases above a second threshold value.
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14. A device manufacturing method using lithographic projection apparatus, the method comprising:
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projecting a beam of radiation onto a selected patterning device and to produce a patterned beam and projecting the patterned beam onto a target portion of a substrate using a projection system;
measuring changes in aberrations of the projection system with time;
predicting variation of projection system aberrations with time on the basis of model parameters;
generating a control signal for compensating a time-varying property of the apparatus;
estimating model parameter errors on the basis of predicted projection system aberration values and measured projection system aberration values, and updating the model parameters in dependence on the model parameter errors such that the time-varying property is maintained predetermined acceptable performance criteria. - View Dependent Claims (15)
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16. A machine readable medium containing machine executable instructions for performing a method comprising:
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projecting a beam of radiation onto a selected patterning device and to produce a patterned beam and projecting the patterned beam onto a target portion of a substrate using a projection system;
measuring changes in aberrations of the projection system with time;
predicting variation of projection system aberrations with time on the basis of model parameters;
generating a control signal for compensating a time-varying property of the apparatus;
estimating model parameter errors on the basis of predicted projection system aberration values and measured projection system aberration values, and updating the model parameters in dependence on the model parameter errors such that the time-varying property is maintained predetermined acceptable performance criteria.
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Specification