AUTOMATIC CALIBRATION OF A MASKING PROCESS SIMULATOR
First Claim
1. A computer-implemented method for automatically calibrating a masking process simulator, comprising the steps of:
- (a) performing a masking process using a calibration mask and process parameters to produce a calibration pattern on a wafer;
(b) creating a digital image of the calibration pattern;
(c) detecting edges of the pattern from the digital image using pattern recognition;
(d) inputting data defining the calibration mask and the process parameters into a process simulator to produce an alim image estimating the calibration pattern that would be produced by the masking process;
(e) overlaying the alim image and the detected edges of the digital image;
(f) measuring a distance between contours of the pattern in the alim image and the detected edges; and
(g) using one or more mathematical algorithms to iteratively change the values of the processing parameters input to the simulator until a set of processing parameter values are found that produces a minimum distance between the contours of the pattern in the alim image and the detected edges, thereby effectively calibrating the process simulator to compensate for process variations of the masking process.
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Abstract
A method and system for automatically calibrating a masking process simulator are disclosed. The method and system include performing a masking process using a calibration mask and process parameters to produce a calibration pattern on a wafer. A digital image is created of the calibration pattern, and the edges of the pattern are detected from the digital image using pattern recognition. Data defining the calibration mask and the process parameters are then input to a process simulator to produce an alim image estimating the calibration pattern that would be produced by the masking process. The method and system further include overlaying the alim image and the detected edges of the digital image, and measuring a distance between contours of the pattern in the alim image and the detected edges. Thereafter, one or more mathematical algorithms are used to iteratively change the values of the processing parameters input to the simulator until a set of processing parameter values are found that produces a minimum distance between the contours of the pattern in the alim image and the detected edges, thereby effectively calibrating the process simulator to compensate for process variations of the masking process.
86 Citations
30 Claims
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1. A computer-implemented method for automatically calibrating a masking process simulator, comprising the steps of:
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(a) performing a masking process using a calibration mask and process parameters to produce a calibration pattern on a wafer;
(b) creating a digital image of the calibration pattern;
(c) detecting edges of the pattern from the digital image using pattern recognition;
(d) inputting data defining the calibration mask and the process parameters into a process simulator to produce an alim image estimating the calibration pattern that would be produced by the masking process;
(e) overlaying the alim image and the detected edges of the digital image;
(f) measuring a distance between contours of the pattern in the alim image and the detected edges; and
(g) using one or more mathematical algorithms to iteratively change the values of the processing parameters input to the simulator until a set of processing parameter values are found that produces a minimum distance between the contours of the pattern in the alim image and the detected edges, thereby effectively calibrating the process simulator to compensate for process variations of the masking process. - View Dependent Claims (2, 14, 15)
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3. The method of claim 3 wherein step (g) further includes the step of:
- changing the values of a subset of the processing parameters.
- View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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16. A process simulator system, comprising:
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a server coupled to a network;
a calibration program executing on the server;
a process simulator executing on the server; and
at least one client computer coupled to the server over the network, such that an operator may access the calibration program, wherein once invoked, the calibration program;
(a) receives a digital image of a calibration pattern on a wafer, the calibration pattern produced during a masking process using a calibration mask and process parameters (b) detects edges of the pattern from the digital image using pattern recognition;
(c) inputs data defining the calibration mask and the process parameters into the process simulator, which then produces an alim image estimating the calibration pattern that would be produced by the masking process;
(d) overlays the alim image and the detected edges of the digital image;
(e) measures a distance between contours of the pattern in the alim image and the detected edges; and
(f) uses one or more mathematical algorithms to iteratively change the values, of the processing parameters input to the simulator until a set of processing parameter values are found that produces a minimum distance between the contours of the pattern in the alim image and the detected edges, thereby effectively calibrating the process simulator to compensate for process variations of the masking process. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification