Method and apparatus for extracting dose and focus from critical dimension data
First Claim
1. A method for monitoring a photolithography system, comprising:
- defining a model of the photolithography system for modeling top and bottom critical dimension data associated with features formed by the photolithography system as a function of dose and focus;
generating a library of model inversions of the model for different combinations of top and bottom critical dimension values, each entry in the library specifying a dose value and a focus value associated with a particular combination of top and bottom critical dimension values;
receiving by a computing device a top critical dimension measurement and a bottom critical dimension measurement of a feature formed by the photolithography system using a commanded dose parameter and a commanded focus parameter;
accessing the library using the top and bottom critical dimension measurements to generate values for a received dose parameter and a received focus parameter in the computing device by;
identifying a set of entries in the library having top and bottom critical dimension values closer to the top and bottom critical dimension measurements than the other entries in the library;
selecting the entry in the set having associated dose and focus values closest to the commanded dose and focus parameters; and
providing the dose and focus values associated with the selected entry as the received dose and focus parameters; and
comparing, by the computing device, the received dose and focus parameters to the commanded dose and focus parameters to characterize the photolithography system.
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Abstract
A method for monitoring a photolithography system includes defining a model of the photolithography system for modeling top and bottom critical dimension data associated with features formed by the photolithography system as a function of dose and focus. A library of model inversions is generated for different combinations of top and bottom critical dimension values. Each entry in the library specifies a dose value and a focus value associated with a particular combination of top and bottom critical dimension values. A top critical dimension measurement and a bottom critical dimension measurement of a feature formed by the photolithography system using a commanded dose parameter and a commanded focus parameter are received. The library is accessed using the top and bottom critical dimension measurements to generate values for a received dose parameter and the received focus parameter. The received dose and focus parameters are compared to the commanded dose and focus parameters to characterize the photolithography system.
10 Citations
20 Claims
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1. A method for monitoring a photolithography system, comprising:
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defining a model of the photolithography system for modeling top and bottom critical dimension data associated with features formed by the photolithography system as a function of dose and focus; generating a library of model inversions of the model for different combinations of top and bottom critical dimension values, each entry in the library specifying a dose value and a focus value associated with a particular combination of top and bottom critical dimension values; receiving by a computing device a top critical dimension measurement and a bottom critical dimension measurement of a feature formed by the photolithography system using a commanded dose parameter and a commanded focus parameter; accessing the library using the top and bottom critical dimension measurements to generate values for a received dose parameter and a received focus parameter in the computing device by; identifying a set of entries in the library having top and bottom critical dimension values closer to the top and bottom critical dimension measurements than the other entries in the library; selecting the entry in the set having associated dose and focus values closest to the commanded dose and focus parameters; and providing the dose and focus values associated with the selected entry as the received dose and focus parameters; and comparing, by the computing device, the received dose and focus parameters to the commanded dose and focus parameters to characterize the photolithography system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system, comprising:
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a photolithography tool operable to generate a feature on a wafer using a commanded dose parameter and a commanded focus parameter; a metrology tool operable to measure a top critical dimension of the feature and a bottom critical dimension of the feature; a photolithography solver operable to define a model of the photolithography tool for modeling top and bottom critical dimension data associated with features formed by the photolithography tool as a function of dose and focus, and generate a library of model inversions of the model for different combinations of top and bottom critical dimension values, each entry in the library specifying a dose value and a focus value associated with a particular combination of top and bottom critical dimension values; a photolithography monitor operable to receive the top critical dimension measurement and the bottom critical dimension measurement, access the library using the top and bottom critical dimension measurements to generate values for a received dose parameter and a received focus parameter by identifying a set of entries in the library having top and bottom critical dimension values closer to the top and bottom critical dimension measurements than the other entries in the library, selecting the entry in the set having associated dose and focus values closest to the commanded dose and focus parameters, and providing the dose and focus values associated with the selected entry as the received dose and focus parameters, and compare the received dose and focus parameters to the commanded dose and focus parameters to characterize the photolithography tool. - View Dependent Claims (19, 20)
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Specification