Three-dimensional mask model for photolithography simulation
First Claim
1. A photolithography simulation system implemented by a computer, the system comprising:
- a three-dimensional mask model of a photolithography mask having certain characteristics, the three-dimensional mask model comprising one or more of;
a correction factor configured to modify a mathematical transform of a mask transmission function of a mask;
a correction factor configured to modify a mathematical transform of a horizontal mask-edge function of the mask;
a correction factor configured to modify a mathematical transform of a vertical mask-edge function of the mask; and
a correction factor configured to modify a mathematical transform of a mask-corner function of the mask,wherein the correction factors represent one or more effects of the topography of the photolithography mask on light passing through a mask having the certain characteristics, and wherein existing symmetry properties of one or more correction factors of the three-dimensional mask model are used to improve computational efficiency; and
a software tool executed by the computer configured to use the three-dimensional mask model to simulate a near-field image expected to be produced by a photolithographic tool using the mask.
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Accused Products
Abstract
A three-dimensional mask model of the invention provides a more realistic approximation of the three-dimensional effects of a photolithography mask with sub-wavelength features than a thin-mask model. In one embodiment, the three-dimensional mask model includes a set of filtering kernels in the spatial domain that are configured to be convolved with thin-mask transmission functions to produce a near-field image. In another embodiment, the three-dimensional mask model includes a set of correction factors in the frequency domain that are configured to be multiplied by the Fourier transform of thin-mask transmission functions to produce a near-field image.
17 Citations
28 Claims
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1. A photolithography simulation system implemented by a computer, the system comprising:
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a three-dimensional mask model of a photolithography mask having certain characteristics, the three-dimensional mask model comprising one or more of; a correction factor configured to modify a mathematical transform of a mask transmission function of a mask; a correction factor configured to modify a mathematical transform of a horizontal mask-edge function of the mask; a correction factor configured to modify a mathematical transform of a vertical mask-edge function of the mask; and a correction factor configured to modify a mathematical transform of a mask-corner function of the mask, wherein the correction factors represent one or more effects of the topography of the photolithography mask on light passing through a mask having the certain characteristics, and wherein existing symmetry properties of one or more correction factors of the three-dimensional mask model are used to improve computational efficiency; and a software tool executed by the computer configured to use the three-dimensional mask model to simulate a near-field image expected to be produced by a photolithographic tool using the mask. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A photolithography simulation system implemented by a computer, the system comprising:
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a three-dimensional mask model of a photolithography mask having certain characteristics, the mask model comprising one or more of a linear and a bilinear filtering kernel, the one or more filtering kernels being configured to represent one or more effects of the topography of the photolithography mask on light passing through a mask having the certain characteristics, and wherein existing symmetry properties of the one or more filtering kernels of the three-dimensional mask model are used to improve computational efficiency; and a software tool executed by the computer configured to use the mask model to simulate a near-field image expected to be produced by a photolithographic tool using the mask, wherein the simulation includes convolving the one or more filtering kernels with one or more representations of the mask. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A method implemented by a computer for creating a three-dimensional mask model, the method comprising:
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simulating the effect of light passing through a mask using three-dimensional mask topography information to produce a theoretical image; determining initial filtering kernels for a three-dimensional mask model using the theoretical, wherein existing symmetry properties of one or more of the initial filtering kernels of the three-dimensional mask model are used to improve computational efficiency; and modifying the initial filtering kernels until a total difference between the theoretical image and a simulated image is minimized or below a predetermined threshold to produce final filtering kernels, wherein the final filtering kernels are configured to be convolved with one or more mask transmission functions to produce a near-field image, and wherein the simulating, determining and modifying steps are implemented using the computer. - View Dependent Claims (16, 17, 18, 19, 20, 25, 26)
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21. A method implemented by a computer for creating a three-dimensional mask model, the method comprising:
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simulating the effect of light passing through a mask using three-dimensional mask topography information to produce a theoretical image; determining initial correction factors for a three-dimensional mask model using the theoretical image, wherein existing symmetry properties of one or more initial correction factors of the three-dimensional mask model are used to improve computational efficiency; and modifying the initial correction factors until a total difference between the theoretical image and a simulated image is minimized to produce final correction factors, wherein the final correction factors are configured to be multiplied by a Fourier transform of one or more mask transmission functions to produce a near-field image, and wherein the simulating, determining and modifying steps are implemented using the computer. - View Dependent Claims (22, 23, 24, 27, 28)
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Specification