Methods and apparatuses for etch profile matching by surface kinetic model optimization
First Claim
1. A method of optimizing a computerized model which relates an etched feature profile on a semiconductor device 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, wherein the independent input parameters comprise an input parameter selected from the group consisting of temperature, plasma density, and etchant flux;
(c) for each set of values specified in (b), receiving an experimental etch profile resulting from an experimental etch process performed using the set of values specified in (b), wherein the experimental etch process comprised various experiments that etch semiconductor substrates and measure resulting experimentally produced feature profiles with one or more metrology tools;
(d) for each set of values specified in (b), generating a computed etch profile from the model using the set of values specified in (a) and (b), wherein the computed etch profile is provided for a grid having a grid spacing of between 1 angstrom and 10 micrometers, and wherein the computed etch profile is generated over a plurality of time steps; and
(e) modifying one or more values specified in (a) for the selected set of model parameters and repeating (d) with the modified one or more values so as to reduce a metric indicative of combined differences between the experimental etch profiles received in (c) and corresponding computed etch profiles generated in (d) over all the sets of values for the selected independent input parameters specified in (b) to thereby produce optimized model parameter values;
wherein calculating the metrics in (e) comprises;
projecting the computed and corresponding experimental etch profiles from a first space having multiple dimensions each representing one of a plurality of feature profile coordinates onto a reduced-dimensional subspace having fewer dimensions than the first space and reducing latent statistical correlations in etch profiles, wherein the reduced-dimensional subspace recasts the modifying operation in (e) to a computationally more efficient process; and
calculating a difference between the profiles as projected onto the subspace.
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Abstract
Disclosed are methods of optimizing a computerized model which relates etched feature profile on a semiconductor device to a set of independent input parameters via the use of a plurality of model parameters. The optimization methods may include modifying the model parameters so that an etch profile generated with the model is such that it reduces a metric indicative of the combined differences between experimental etch profiles resulting from experimental etch processes performed using different sets of values for sets of independent input parameters and computed etch profiles generated from the model and corresponding to the experimental etch profiles. Said metric may be calculated by projecting computed and corresponding experimental etch profiles onto a reduced-dimensional subspace used to calculate a difference between the profiles. Also disclosed herein are systems employing such optimized models, as well as methods of using such models to approximately determine the profile of an etched feature.
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Citations
33 Claims
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1. A method of optimizing a computerized model which relates an etched feature profile on a semiconductor device 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, wherein the independent input parameters comprise an input parameter selected from the group consisting of temperature, plasma density, and etchant flux; (c) for each set of values specified in (b), receiving an experimental etch profile resulting from an experimental etch process performed using the set of values specified in (b), wherein the experimental etch process comprised various experiments that etch semiconductor substrates and measure resulting experimentally produced feature profiles with one or more metrology tools; (d) for each set of values specified in (b), generating a computed etch profile from the model using the set of values specified in (a) and (b), wherein the computed etch profile is provided for a grid having a grid spacing of between 1 angstrom and 10 micrometers, and wherein the computed etch profile is generated over a plurality of time steps; and (e) modifying one or more values specified in (a) for the selected set of model parameters and repeating (d) with the modified one or more values so as to reduce a metric indicative of combined differences between the experimental etch profiles received in (c) and corresponding computed etch profiles generated in (d) over all the sets of values for the selected independent input parameters specified in (b) to thereby produce optimized model parameter values; wherein calculating the metrics in (e) comprises; projecting the computed and corresponding experimental etch profiles from a first space having multiple dimensions each representing one of a plurality of feature profile coordinates onto a reduced-dimensional subspace having fewer dimensions than the first space and reducing latent statistical correlations in etch profiles, wherein the reduced-dimensional subspace recasts the modifying operation in (e) to a computationally more efficient process; and calculating a difference between the profiles as projected onto the subspace. - 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)
wherein; the memory stores an etched feature profile model optimized by the method of claim 1; and the processor uses the etched feature profile model stored in the memory to compute an etched feature profile from a set of values for the set of independent input parameters.
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16. The system of claim 15, wherein the controller adjusts the operation of the etcher apparatus by varying one or more values of the set of independent input parameters in response to the computed etched feature profile.
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17. The system of claim 16, wherein the set of independent input parameters whose values are varied in response to the computed etched feature profile include one or more parameters selected from:
- RF plasma frequency and RF plasma power level.
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18. The system of claim 15, wherein the etcher apparatus comprises:
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a processing chamber; a substrate holder for holding a substrate within the processing chamber; a plasma generator for generating a plasma within the processing chamber, the plasma generator comprising an RF power supply; one or more valve-controlled process gas inlets for flowing one or more process gases into the processing chamber; and one or more gas outlets fluidically connected to one or more vacuum pumps for evacuating gases from the processing chamber.
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19. The system of claim 18, wherein the controller adjusts the frequency and/or the power level of the RF power supply to modify characteristics of the plasma in the processing chamber in response to the computed etched feature profile.
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20. The system of claim 18, wherein the controller operates the one or more valve-controlled process gas inlets to adjust the flow rates of one or more process gases into the processing chamber in response to the computed etched feature profile.
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21. The system of claim 18, wherein the controller adjusts a temperature and/or a pressure within the processing chamber in response to the computed etched feature profile.
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22. The method of claim 1, further comprising:
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(f) optimizing the computer model by applying one or more modified values produced in (e) to the computer model; and (g) using the optimized computer model produced in (f) to develop a lithographic mask.
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23. The method of claim 1, further comprising:
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(f) optimizing the computer model by applying one or more modified values produced in (e) to the computer model; and (g) etching a semiconductor substrate using a set of etch conditions determined using the optimized computer model produced in (f).
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24. The method of claim 1, further comprising:
(f) using the model with the optimized model parameter values to enable development of a lithographic mask and/or enable etching a semiconductor substrate using a set of etch conditions.
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25. A method of optimizing a computerized model which relates an etched feature profile to a set of independent input parameters via the use 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, wherein the independent input parameters comprise an input parameter selected from the group consisting of temperature, plasma density, and etchant flux; (c) for each set of values specified in (b), receiving an experimental etch profile resulting from an experimental etch process performed using the set of values specified in (b), wherein the experimental etch process comprised various experiments that etch semiconductor substrates and measure resulting experimentally produced feature profiles with one or more metrology tools; (d) for each set of values specified in (b), generating a computed etch profile from the model using the set of values specified in (a) and (b) , wherein the computed etch profile is provided for a grid having a grid spacing of between 1 angstrom and 10 micrometers, and wherein the computed etch profile is generated over a plurality of time steps; and (e) modifying one or more values specified in (a) for the selected set of model parameters and repeating (d) with the modified one or more values so as to reduce a metric indicative of combined differences between the experimental etch profiles measured in(c) and corresponding computed etch profiles generated in (d) over all the sets of values for the selected independent input parameters specified in (b) to thereby produce optimized model parameter values; wherein calculating the metrics in (e) comprises; differencing the computed and corresponding experimental etch profiles in a first space having multiple dimensions each representing one of a plurality of feature profile coordinates; and projecting the differences onto a reduced-dimensional subspace having fewer dimensions than the first space and reducing latent statistical correlations in etch profiles, wherein the reduced-dimensional subspace recasts the modifying operation in (e) to a computationally more efficient process. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33)
wherein; the memory stores an etched feature profile model optimized by the method of claim 25; and the processor uses the etched feature profile model stored in the memory to compute an etched feature profile from a set of values for the set of independent input parameters.
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33. The system of claim 32, wherein the controller adjusts the operation of the etcher apparatus by varying one or more values of the set of independent input parameters in response to the computed etched feature profile.
Specification