Method for time-evolving rectilinear contours representing photo masks
First Claim
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1. A method of representing a photomask pattern that includes a number of different regions having different optical properties, the method comprising:
- providing a function having input values corresponding to the area of the photomask and output values indicating the position of a contour of the photomask pattern, wherein the function results in at least three different output values over the area of the photomask; and
wherein the number of the different output values over the area of the photomask is greater than the number of the different regions having the different optical properties;
evaluating the function over at least a portion of the area of the photomask; and
storing the output values from the function in a data structure to represent the position of the contour of the pattern over the portion of the area of the photomask.
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Abstract
Photomask patterns are represented using contours defined by level-set functions. Given target pattern, contours are optimized such that defined photomask, when used in photolithographic process, prints wafer pattern faithful to target pattern. Optimization utilizes “merit function” for encoding aspects of photolithographic process, preferences relating to resulting pattern (e.g. restriction to rectilinear patterns), robustness against process variations, as well as restrictions imposed relating to practical and economic manufacturability of photomasks.
104 Citations
22 Claims
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1. A method of representing a photomask pattern that includes a number of different regions having different optical properties, the method comprising:
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providing a function having input values corresponding to the area of the photomask and output values indicating the position of a contour of the photomask pattern, wherein the function results in at least three different output values over the area of the photomask; and wherein the number of the different output values over the area of the photomask is greater than the number of the different regions having the different optical properties; evaluating the function over at least a portion of the area of the photomask; and storing the output values from the function in a data structure to represent the position of the contour of the pattern over the portion of the area of the photomask. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification