Methods and apparatuses for etch profile optimization by reflectance spectra matching and surface kinetic model optimization
First Claim
1. A method of generating a lithography mask by optimizing a computer model which relates an etch profile of a feature on a semiconductor substrate to a set of independent input parameters, via the use of a plurality of model parameters, the method comprising:
- (a) identifying a set of values for a selected set of the model parameters to be optimized;
(b) identifying multiple sets of values for a selected set of independent input parameters to optimize over;
(c) for each set of values specified in (b), receiving an experimental reflectance spectra generated from an optical measurement of an experimental etch process performed using the set of values specified in (b);
(d) for each set of values specified in (b), generating a computed reflectance spectra from the model using the set of values specified in (a) and (b);
(e) modifying one or more values specified in (a) for the selected set of model parameters and repeating (d) with the modified set of values so as to reduce a metric indicative of the differences between the experimental reflectance spectra received in (c) and corresponding computed reflectance spectra generated in (d) with respect to one or more sets of values for the selected independent input parameters specified in (b), thereby producing modified values for the selected set of model parameters;
wherein calculating the metric in (e) comprises an operation of;
(1) calculating the differences between the computed and corresponding experimental reflectance spectra and projecting the differences onto a reduced-dimensional subspace; and
/or(2) projecting the computed and corresponding experimental reflectance spectra onto a reduced-dimensional subspace and calculating the difference between the reflectance spectra as projected onto the reduced-dimensional subspace;
(f) using the computer model with the modified values for the selected set of model parameters to design the lithographic mask; and
(g) generating the lithographic mask based on the design generated by the computer model in (f).
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Abstract
Disclosed are methods of optimizing a computer model which relates the etch profile of a feature on a semiconductor substrate to a set of independent input parameters (A), via the use of a plurality of model parameters (B). In some embodiments, the methods may include modifying one or more values of B so as to reduce a metric indicative of the differences between computed reflectance spectra generated from the model and corresponding experimental reflectance spectra with respect to one or more sets of values of A. In some embodiments, calculating the metric may include an operation of projecting the computed and corresponding experimental reflectance spectra onto a reduced-dimensional subspace and calculating the difference between the reflectance spectra as projected onto the subspace. Also disclosed are etch systems implementing such optimized computer models.
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Citations
34 Claims
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1. A method of generating a lithography mask by optimizing a computer model which relates an etch profile of a feature on a semiconductor substrate to a set of independent input parameters, via the use of a plurality of model parameters, the method comprising:
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(a) identifying a set of values for a selected set of the model parameters to be optimized; (b) identifying multiple sets of values for a selected set of independent input parameters to optimize over; (c) for each set of values specified in (b), receiving an experimental reflectance spectra generated from an optical measurement of an experimental etch process performed using the set of values specified in (b); (d) for each set of values specified in (b), generating a computed reflectance spectra from the model using the set of values specified in (a) and (b); (e) modifying one or more values specified in (a) for the selected set of model parameters and repeating (d) with the modified set of values so as to reduce a metric indicative of the differences between the experimental reflectance spectra received in (c) and corresponding computed reflectance spectra generated in (d) with respect to one or more sets of values for the selected independent input parameters specified in (b), thereby producing modified values for the selected set of model parameters; wherein calculating the metric in (e) comprises an operation of; (1) calculating the differences between the computed and corresponding experimental reflectance spectra and projecting the differences onto a reduced-dimensional subspace; and
/or(2) projecting the computed and corresponding experimental reflectance spectra onto a reduced-dimensional subspace and calculating the difference between the reflectance spectra as projected onto the reduced-dimensional subspace; (f) using the computer model with the modified values for the selected set of model parameters to design the lithographic mask; and (g) generating the lithographic mask based on the design generated by the computer model in (f). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method of etching a semiconductor substrate by optimizing a computer model which relates the etch profile of a feature on a semiconductor substrate to a set of independent input parameters, via the use of a plurality of model parameters, the method comprising:
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(a) identifying a set of values for a selected set of the model parameters to be optimized; (b) identifying multiple sets of values for a selected set of independent input parameters to optimize over; (c) for each set of values specified in (b), receiving an experimental reflectance spectra generated from an optical measurement of an etch process performed using the set of values specified in (b); (d) for each set of values specified in (b), generating a computed reflectance spectra from the model using the set of values specified in (a) and (b); (e) modifying one or more values specified in (a) for the selected set of model parameters and repeating (d) with the modified set of values so as to reduce a metric indicative of the differences between the experimental reflectance spectra received in (c) and corresponding computed reflectance spectra generated in (d) with respect to one or more sets of values for the selected independent input parameters specified in (b), thereby producing modified values for the selected set of model parameters; (f) using the computer model with the modified values for the selected set of model parameters to determine a set of etch conditions; and (g) etching the semiconductor substrate using the set of etch conditions. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34)
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Specification