Lithographic apparatus and device manufacturing method utilizing data filtering
First Claim
1. A lithography apparatus, comprising:
- a projection system that projects a beam of radiation onto a substrate as an array of sub-beams of radiation;
a patterning device that modulates the sub-beams of radiation to substantially produce a requested dose pattern on the substrate, the dose pattern being built up from an array of spot exposures in which at least neighboring ones of the spot exposures are imaged incoherently with respect to each other and each of the spot exposures is produced by one of the sub-beams of radiation at a particular time;
a low-pass filter that operates on pattern data derived from the requested dose pattern in order to form a frequency-clipped target dose pattern that predominantly comprises only spatial frequency components below a selected threshold frequency; and
a data manipulation device that produces a control signal comprising spot exposure intensities to be produced by the patterning device, based on a direct algebraic least-squares fit of the spot exposure intensities to the frequency-clipped target dose pattern.
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Accused Products
Abstract
An apparatus and method are used to form patterns on a substrate. The comprise a projection system, a patterning device, a low-pass filter, and a data manipulation device. The projection system projects a beam of radiation onto the substrate as an array of sub-beams of radiation. The patterning device modulates the sub-beams of radiation to substantially produce a requested dose pattern on the substrate. The low-pass filter operates on pattern data derived from the requested dose pattern in order to form a frequency-clipped target dose pattern that comprises only spatial frequency components below a selected threshold frequency. The data manipulation device produces a control signal comprising spot exposure intensities to be produced by the patterning device, based on a direct algebraic least-squares fit of the spot exposure intensities to the frequency-clipped target dose pattern. In various examples, filters for pattern sharpening, image log slope control, and/or CD biasing can also be used.
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Citations
40 Claims
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1. A lithography apparatus, comprising:
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a projection system that projects a beam of radiation onto a substrate as an array of sub-beams of radiation;
a patterning device that modulates the sub-beams of radiation to substantially produce a requested dose pattern on the substrate, the dose pattern being built up from an array of spot exposures in which at least neighboring ones of the spot exposures are imaged incoherently with respect to each other and each of the spot exposures is produced by one of the sub-beams of radiation at a particular time;
a low-pass filter that operates on pattern data derived from the requested dose pattern in order to form a frequency-clipped target dose pattern that predominantly comprises only spatial frequency components below a selected threshold frequency; and
a data manipulation device that produces a control signal comprising spot exposure intensities to be produced by the patterning device, based on a direct algebraic least-squares fit of the spot exposure intensities to the frequency-clipped target dose pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A lithography apparatus, comprising:
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a projection system that projects a beam of radiation onto a substrate as an array of sub-beams of radiation;
a patterning device that modulates the sub-beams of radiation to substantially produce a requested dose pattern on the substrate, the dose pattern being built up from an array of spot exposures in which at least neighboring ones of the spot exposures are imaged incoherently with respect to each other and each of the spot exposures is produced by one of the sub-beams of radiation at a particular time;
a data manipulation device that produces a control signal comprising spot exposure intensities to be produced by the patterning device, based on a direct algebraic least-squares fit of spot exposure intensities to data derived from the requested dose pattern, wherein the least-squares fit is performed by multiplying a pseudo-inverted form of a point-spread function matrix by a column vector representing the pattern data derived from the requested dose pattern, the point-spread function matrix comprising information about a shape and relative position of the point-spread function of each spot to be exposed on the substrate by one of the sub-beams of radiation at a given time; and
a low-pass filter that removes spatial frequency components of a signal above a selected threshold frequency, incorporated offline into the pseudo-inverted form of the point-spread-function matrix, ready for the least-squares fit, by the following operation;
[K]+filtered=Flow-pass filter{circle around (×
)}[K]+wherein [K]+ and [K]+ filtered represent the pseudo-inverted form of the point-spread function matrix respectively before and after filtering, wherein Flow-pass filter represents a mathematical definition of the low-pass filter in a spatial domain. - View Dependent Claims (18, 19, 20)
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21. A lithography apparatus, comprising:
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a projection system that projects a beam of radiation onto a substrate as an array of sub-beams of radiation;
an array of individually controllable elements that modulates the sub-beams of radiation so as substantially to form a requested dose pattern on the substrate, the requested dose pattern being built up over time from an array of spot exposures, each of the spot exposures being produced by one of the sub-beams of radiation at a given time;
a rasterizer device that converts data defining the requested dose pattern to a sequence of data representing the requested dose at a corresponding sequence of points within the pattern;
a data manipulation device that receives the sequence of data and generates a control signal therefrom, the control signal being used to control the array of individually controllable elements; and
a focus determination unit that measures a position of at least a portion of the substrate relative to a plane of best focus, wherein the data manipulation device comprises a focus compensation unit that changes the control signal based on measured deviations of the at least a portion of the substrate relative to the plane of best focus. - View Dependent Claims (22)
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23. A lithography apparatus, comprising:
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a patterning device that modulates a beam of radiation;
a projection system that projects the modulated beam of radiation onto a substrate; and
a CD-biasing filter that operates on pattern data derived from a requested dose pattern that is to be transmitted to the patterning device, which controls critical dimension characteristics of a radiation dose pattern produced by the patterning device. - View Dependent Claims (24, 25, 26)
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27. A lithography apparatus, comprising:
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an illumination system that conditions a beam of radiation;
a projection system that projects the beam of radiation onto the substrate as an array of sub-beams of radiation;
a patterning device that modulates the sub-beams of radiation to substantially produce a requested dose pattern on the substrate, the dose pattern being built up from an array of spot exposures, each of the spot exposure being produced by one of the sub-beams of radiation at a particular time, wherein the radiation intensity of a given sub-beam of radiation is controlled according to an activation state of a corresponding portion of the patterning device; and
a data manipulation device that transforms a signal comprising spot exposure radiation doses derived from the requested dose pattern to a control signal representing activation states of the patterning device to produce the requested dose pattern, wherein the transformation corrects for intensity variations caused by at least one of components of the projection system, components of the illumination system, radiation sources for the illumination system, and components of the patterning device. - View Dependent Claims (28, 29)
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30. A device manufacturing method, comprising:
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projecting a beam of radiation onto a substrate as an array of sub-beams of radiation;
modulating the sub-beams of radiation to substantially produce a requested dose pattern on the substrate, the dose pattern being built up from an array of spot exposures in which at least neighboring one of the spot exposures are imaged incoherently with respect to each other and each of the spot exposures is produced by one of the sub-beams of radiation at a particular time;
filtering pattern data derived from the requested dose pattern in order to form a frequency-clipped target dose pattern that comprises only spatial frequency components below a selected threshold frequency; and
producing a control signal comprising spot exposure intensities to be produced by the modulating, based on a direct algebraic least-squares fit of the spot exposure intensities to the frequency-clipped target dose pattern. - View Dependent Claims (35)
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31. A device manufacturing method, comprising:
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projecting a beam of radiation onto a substrate as an array of sub-beams of radiation;
modulating the sub-beams of radiation to substantially produce a requested dose pattern on the substrate, the dose pattern being built up from an array of spot exposures in which at least neighboring ones of the spot exposures are imaged incoherently with respect to each other and each of the spot exposures is produced by one of the sub-beams of radiation at a particular time;
producing a control signal comprising spot exposure intensities to be produced by the modulating, based on a direct algebraic least-squares fit of the spot exposure intensities to data derived from the requested dose pattern, wherein the least-squares fit is performed by multiplying a pseudo-inverted form of a point-spread function matrix by a column vector representing the pattern data derived from the requested dose pattern, the point-spread function matrix comprising information about the shape and relative position of the point-spread function of each spot to be exposed on the substrate by one of the sub-beams of radiation at a given time; and
filtering to remove spatial frequency components of a signal above a selected threshold frequency, incorporated offline into the pseudo-inverted form of the point-spread-function matrix, ready for the least-squares fit, by the following operation;
[K]+filtered=Flow-pass filter{circle around (×
)}[K]+wherein [K]+ and [K]+filtered represent the pseudo-inverted form of the point-spread function matrix respectively before and after filtering, and where Flow pass filter represents a mathematical definition of the filtering in the spatial domain. - View Dependent Claims (36)
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32. A device manufacturing method, comprising:
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projecting a beam of radiation onto a substrate as an array of sub-beams of radiation;
modulating the sub-beams of radiation to substantially to form a requested dose pattern on the substrate, the requested dose pattern being built up over time from an array of spot exposures, each of the spot exposures being produced by one of the sub-beams of radiation at a given time;
converting data defining the requested dose pattern to a sequence of data representing the requested dose at a corresponding sequence of points within the pattern;
generating a control signal from the sequence of data that is used to control the modulating;
measuring the position of at least a portion of the substrate relative to a plane of best focus; and
modifying the control signal based on measured deviations of the at least a portion of the substrate relative to the plane of best focus. - View Dependent Claims (37)
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33. A device manufacturing method, comprising:
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modulating a beam of radiation;
projecting the modulated beam of radiation onto a substrate; and
CD-biasing filtering the pattern data derived from a requested dose pattern, which is used to perform the modulating, in order to control critical dimension characteristics of a radiation dose pattern produced by the modulating. - View Dependent Claims (38, 40)
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34. A device manufacturing method, comprising:
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conditioning a beam of radiation;
projecting the beam of radiation onto the substrate as an array of sub-beams of radiation;
modulating the sub-beams of radiation to substantially produce a requested dose pattern on the substrate, the dose pattern being built up from an array of spot exposures, each of the spot exposures being produced by one of the sub-beams of radiation at a particular time;
controlling radiation intensity of a given one of the sub-beams of radiation according to an activation state of a corresponding portion of a patterning device that performs the modulating;
transforming a signal comprising spot exposure radiation doses derived from the requested dose pattern to a control signal representing activation states of the patterning device to substantially produce the requested dose pattern; and
modifying the transforming step to correct for intensity variations caused by at least one of components of the projection system, components of the illumination system, radiation sources for the illumination system, and components of the patterning device. - View Dependent Claims (39)
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Specification