摘要:
A method is provided for modeling lithographic processes in the design of photomasks for the manufacture of semiconductor integrated circuits, and more particularly for simulating intermediate range flare effects. For a region of influence (ROI) from first ROI1 of about 5λ/NA to distance ROI2 when the point spread function has a slope that is slowly varying according to a predetermined criterion, then mask shapes at least within the distance range from ROI1 to ROI2 are smoothed prior to computing the SOCS convolutions. The method provides a fast method for simulating intermediate range flare effects with sufficient accuracy.
摘要:
A method is provided for designing a mask that includes the use of a pixel-based simulation of a lithographic process model, in which test structures are designed for determining numerical and discretization errors associated with the pixel grid as opposed to other model inaccuracies. The test structure has a plurality of rows of the same sequence of features, but each row is offset from other rows along an x-direction by a multiple of a minimum step size, such as used in modifying masks during optical proximity correction. The images for each row are simulated with a lithographic model that uses the selected pixel-grid size and the differences between row images are compared. If the differences between rows exceed or violate a predetermined criterion, the pixel grid size may be modified to minimize discretization and/or numerical errors due to the choice of pixel grid size.
摘要:
A method is provided for modeling lithographic processes in the design of photomasks for the manufacture of semiconductor integrated circuits, and more particularly for simulating intermediate range flare effects. For a region of influence (ROI) from first ROI1 of about 5λ/NA to distance ROI2 when the point spread function has a slope that is slowly varying according to a predetermined criterion, then mask shapes at least within the distance range from ROI1 to ROI2 are smoothed prior to computing the SOCS convolutions. The method provides a fast method for simulating intermediate range flare effects with sufficient accuracy.
摘要:
A method is provided for designing a mask that includes the use of a pixel-based simulation of a lithographic process model, in which test structures are designed for determining numerical and discretization errors associated with the pixel grid as opposed to other model inaccuracies. The test structure has a plurality of rows of the same sequence of features, but each row is offset from other rows along an x-direction by a multiple of a minimum step size, such as used in modifying masks during optical proximity correction. The images for each row are simulated with a lithographic model that uses the selected pixel-grid size and the differences between row images are compared. If the differences between rows exceed or violate a predetermined criterion, the pixel grid size may be modified to minimize discretization and/or numerical errors due to the choice of pixel grid size.
摘要:
Methods, and a program storage device for executing such methods, for performing model-based optical proximity correction by providing a mask matrix having a region of interest (ROI) and locating a plurality of points of interest within the mask matrix. A first polygon having a number of vertices representative of the located points of interest is computed, followed by determining a spatial relation between its vertices and the ROI. The vertices of the first polygon are then pinned to boundaries of and within the ROI such that a second polygon is formed on the ROI. The process is repeated for all vertices of the first polygon such that the second polygon is collapsed onto the ROI. This collapsed second polygon is then used to correct for optical proximity.
摘要:
A fast method of verifying a lithographic mask design is provided wherein catastrophic errors are identified by iteratively simulating and verifying images for the mask layout using progressively more accurate image models, including optical and resist models. Progressively accurate optical models include SOCS kernels that provide successively less influence. Corresponding resist models are constructed that may include only SOCS kernel terms corresponding to the optical model, or may include image trait terms of varying influence ranges. Errors associated with excessive light, such as bridging, side-lobe or SRAF printing errors, are preferably identified with bright field simulations, while errors associated with insufficient light, such as necking or line-end shortening overlay errors, are preferably identified with dark field simulations.
摘要:
Embodiments of the present invention provide a method of performing printability verification of a mask layout. The method includes creating one or more tight clusters; computing a set of process parameters associated with a point on said mask; comparing said set of process parameters to said one or more tight clusters; and reporting an error when at least one of said process parameters is away from said one or more tight clusters.
摘要:
A fast method of verifying a lithographic mask design is provided wherein catastrophic errors are identified by iteratively simulating and verifying images for the mask layout using progressively more accurate image models, including optical and resist models. Progressively accurate optical models include SOCS kernels that provide successively less influence. Corresponding resist models are constructed that may include only SOCS kernel terms corresponding to the optical model, or may include image trait terms of varying influence ranges. Errors associated with excessive light, such as bridging, side-lobe or SRAF printing errors, are preferably identified with bright field simulations, while errors associated with insufficient light, such as necking or line-end shortening overlay errors, are preferably identified with dark field simulations.
摘要:
A first method to compute a phase map within an optical proximity correction simulation kernel utilizes simulated wavefront information from randomly generated data. A second method uses measured data from optical tools. A phase map is created by analytically embedding a randomly generated two-dimensional array of complex numbers of wavefront information, and performing an inverse Fourier Transform on the resultant array. A filtering function requires the amplitude of each element of the array to be multiplied by a Gaussian function. A power law is then applied to the array. The elements of the array are shuffled, and converted from the phasor form to real/imaginary form. A two-dimensional Fast Fourier Transform is applied. The array is then unshuffled, and converted back to phasor form.
摘要:
A method, system and computer program product for rendering a mask are disclosed. A method of rendering a mask may comprise: providing an initial mask design for a photolithographic process, the initial mask design including polygons; initially rendering the initial mask design as a coarse mask representation in a pixel based image calculation; identifying an overhang portion; and rendering the overhang portion using a set of subpixels whose artifacts from spatial-localization lie outside a practical resolution of a pseudo lens having a numerical aperture larger than that of a projection lens used in the photolithographic process; and updating the initial rendering based on the overhang portion rendering.