METHOD OF SIMULTANEOUS LITHOGRAPHY AND ETCH CORRECTION FLOW
First Claim
1. A method of modifying a photomask design comprising:
- running, on a computer system, a first lithographic process model simulation that results in generating line or space features of a mask in a first process window;
running, on the computer system, a second etch process model simulation resulting in the generating of line or space features of said mask in a second process window;
determining whether a line feature or a space feature resulting from running each said first process model simulation and second process model simulation meet a respective line feature specification and space feature specification; and
modifying a mask design within a single iteration of an iterative loop process such that the simulated line feature or the simulated space feature are within each of a respective minimum critical dimension (CD) specification; and
such that a common process window (PW) optimized between lithography and etch is obtained, wherein said lithographic and etch processes are simultaneously co-optimized within the iterative loop processing.
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Abstract
A method of mask correction where two independent process models are analyzed and co-optimized simultaneously. In the method, a first lithographic process model simulation is run on a computer system that results in generating a first mask size in a first process window. Simultaneously, a second hard mask open etch process model simulation is run resulting in generating a second mask size in a second process window. Each first lithographic process model and second hard mask open etch process model simulations are analyzed in a single iterative loop and a common process window (PW) optimized between lithography and etch is obtained such that said first mask size and second mask size are centered between said common PW. Further, an etch model form is generated that accounts for differences in an etched pattern due to variation in three-dimensional photoresist profile, the model form including both optical and density terms that directly relate to an optical image.
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Citations
21 Claims
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1. A method of modifying a photomask design comprising:
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running, on a computer system, a first lithographic process model simulation that results in generating line or space features of a mask in a first process window; running, on the computer system, a second etch process model simulation resulting in the generating of line or space features of said mask in a second process window; determining whether a line feature or a space feature resulting from running each said first process model simulation and second process model simulation meet a respective line feature specification and space feature specification; and modifying a mask design within a single iteration of an iterative loop process such that the simulated line feature or the simulated space feature are within each of a respective minimum critical dimension (CD) specification; and
such that a common process window (PW) optimized between lithography and etch is obtained, wherein said lithographic and etch processes are simultaneously co-optimized within the iterative loop processing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system of modifying a photomask design comprising:
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a memory storage device; a hardware processor in communication with said memory storage device and configured to; run a first lithographic process model simulation that results in generating line or space features of a mask in a first process window; run a second etch process model simulation resulting in the generating of line or space features of said mask in a second process window; determine whether a line feature or a space feature resulting from running each said first process model simulation and second process model simulation meet a respective line feature specification and space feature specification; and modify a mask or mask fragment design within a single iteration of an iterative loop process such that the simulated line feature or the simulated space feature are within each of a respective minimum critical dimension (CD) specification; and
such that a common process window (PW) optimized between lithography and etch is obtained, wherein said lithographic and etch processes are simultaneously co-optimized within the iterative loop processing. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for simulating an etching process comprising:
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evaluating an optical imaging model to generate optical parameters based on a mask design; inputting said optical parameters in an etch process model, and simulating an etch process using said etch process model, wherein an efficient and accurate simulation of an etched pattern is generated.
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18. A calibration method for an etch process model comprising:
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obtaining an etch process model form that accounts for differences in an etched pattern due to variation in a three-dimensional photoresist profile, the model form including optical parameters that directly relate to an optical image and having one or more calibration coefficients; obtaining one or more CD measurements of an etched pattern or patterns, and fitting said one or more said calibration coefficients of said etch process model form to one or more CD measurements. - View Dependent Claims (19)
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20. A system for simulating an etching process comprising:
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a memory storage device; a hardware processor in communication with said memory storage device and configured to; evaluate an optical imaging model to generate optical parameters based on a mask design; and input said optical parameters in an etch process model, and simulate an etching process using said etch process model,
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21. A system for calibrating an etching process comprising:
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a memory storage device; a hardware processor in communication with said memory storage device and configured to; obtain an etch process model form that accounts for differences in an etched pattern due to variation in a three-dimensional photoresist profile, the model form including optical parameters that directly relate to an optical image and having one or more calibration coefficients; obtain one or more CD measurements of an etched pattern or patterns, and fit said one or more said calibration coefficients of said etch process model form to one or more CD measurements.
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Specification