Lithographic projection apparatus and device manufacturing method using such lithographic projection apparatus

• US 20060114437A1
• Filed: 12/01/2004
• Published: 06/01/2006
• Est. Priority Date: 12/01/2004
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Baselmans, Johannes Jacobus Matheus, Jeunink, Andre Bernardus, De Groot, Simon, Akhssay, M'hamed, Tel, Wim Tjibbo, Van De Stadt, Arnout, Commissaris, Franciscus Antonius Chrysogonus Marie, Van Der Hoff, Alexander Hendrikus Martinus
• Granted Patent: US 7,262,831 B2
• Time in Patent Office: Days
• US Class Current: 355/55
• CPC Class Codes: G03F 7/70258 Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G03F 7/706 Aberration measurement
• CPC Class Codes: G03F 7/70891 Temperature

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.

Claims

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.

2. Lithographic projection apparatus according to claim 1, wherein a measurement timing system is provided for triggering measurements by the measurement system such that a time interval between measurements is increased if the model parameter error decreases, and the time interval between measurements is decreased if the model parameter error increases.

3. Lithographic projection apparatus according to claim 1, further comprising a comparator for comparing the control signal to a threshold and for supplying a realignment signal to a realignment system when the control signal exceeds the threshold in order to trigger further projection system aberration measurement, thereby providing updated measured aberration values.

4. Lithographic projection apparatus according to claim 3, wherein the comparator is adapted to compare the control signal to a threshold determined by a user-defined lithographic specification selected according to a particular imaging application.

5. Lithographic projection apparatus according to claim 1, wherein the measurement system serves to measure changes in projection system aberrations with time during exposure of a lot of substrates and, when triggered to do so, to effect a further measurement at a predetermined time during the exposure of the lot of substrates, such measurements preferably being made after exposure of a current substrate and before the start of exposure of a subsequent substrate.

6. Lithographic projection apparatus according to claim 1, wherein a modelling system is provided for determining the application-specific effect of the predicted projection system aberration variation on one or more parameters of the image of selected patterning device to be used in the apparatus for producing a specific required patterned beam.

7. Lithographic projection apparatus according to claim 6, wherein the modelling system stores measurement history and exposure information history, for use in updating of the model parameters of the predictive control system.

8. Lithographic projection apparatus according to claim 6, wherein the modelling system is configured and arranged to determine the application-specific effect on the basis of data indicative of the selected patterning device and an illumination mode setting of the projection system.

9. Lithographic projection apparatus according to claim 1, wherein the predictive control system is configured to generate a control signal specific to the required patterned beam according to the predicted projection system aberration variation and its application-specific effect on one or more parameters of the image.

10. Lithographic projection apparatus according to claim 1, wherein an adjustment system is provided for carrying out imaging adjustments based at least in part on the control signal to compensate for the effect of the predicted projection system aberration variation on the image of the selected patterning device.

11. Lithographic projection apparatus according to claim 1, wherein the predictive control system is arranged to generate the control signal in accordance with known sensitivities of the selected patterning device to projection system aberrations and a defined merit function determining relative weightings to be given to different projection system aberrations.

12. Lithographic projection apparatus according to claim 1, wherein the predictive control system is arranged to determine the projection system aberration variation on the basis of a lens heating model that predicts changes in at least one aberration value with time as a result of lens heating or cooling.

13. 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 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.

14. A device manufacturing method using lithographic projection apparatus, the method comprising:

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.

15. A method according to claim 14, further comprising:

generating a realignment signal when the control signal exceeds a threshold in order to trigger further projection system aberration measurement, to thereby supply updated measured aberration values; and

using the updated measured aberration values to predict projection system aberration variation.

16. A machine readable medium containing machine executable instructions for performing a method comprising:

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.