Method and apparatus for fracturing polygons on masks used in an optical lithography process
AssigneeNumerical Technologies, Inc.
InventorBruce Luttrell
Life of this patent
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Abstract
A system for fracturing polygons on masks used in lithography processes for manufacturing an integrated circuit is described. The system fractures polygons that include cavities in either the horizontal edges or the vertical edges by examining the aspect ratio (length/width) of prospective slices made at each vertex of the polygon. After determining the aspect ratio of each prospective slice, the system selects the slice with the lowest aspect ratio and slices the polygon into two sub-polygons. Slicing the polygon in this manner effectively eliminates “slivers” or slices with extreme aspect ratios. This process is continued until each sub-polygon is either a rectangle or a trapezoid that can be printed by electron beam photolithography.
Claims20
A method for fracturing polygons on masks used in an optical lithography process for manufacturing an integrated circuit, comprising:
- receiving a mask layout to be used in fabricating the integrated circuit, wherein the mask layout includes a polygon that defines a desired feature on the integrated circuit, and wherein the polygon is x-convex or y-convex and wherein the polygon includes a plurality of vertices;
- calculating an aspect ratio for each possible slice that extends from a given vertex in the plurality of vertices, wherein the aspect ratio for a slice is the slice length divided by a smaller of two resulting widths on either side of the slice;
- selecting the slice with a smallest aspect ratio;
- and
- applying the slice with the smallest aspect ratio to the polygon, wherein selecting the slice with the smallest aspect ratio avoids slices that create extreme aspect ratios.
A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for fracturing polygons on masks used in an optical lithography process for manufacturing an integrated circuit, the method comprising:
- receiving a mask layout to be used in fabricating the integrated circuit, wherein the mask layout includes a polygon that defines a desired feature on the integrated circuit, and wherein the polygon is x-convex or y-convex and wherein the polygon includes a plurality of vertices;
- calculating an aspect ratio for each possible slice that extends from a given vertex in the plurality of vertices, wherein the aspect ratio for a slice is the slice length divided by a smaller of two resulting widths on either side of the slice;
- selecting the slice with a smallest aspect ratio;
- and
- applying the slice with the smallest aspect ratio to the polygon, wherein selecting the slice with the smallest aspect ratio avoids slices that create extreme aspect ratios.
A mask having structures that were fractured for use in an optical lithography process for manufacturing an integrated circuit:
- wherein the mask to be used in fabricating the integrated circuit includes a polygon that defines a desired feature on the integrated circuit, and wherein the polygon is x-convex or y-convex but not both x-convex and y-convex;
- and
- wherein the polygon has been sliced so that slivers are not created by:
- calculating an aspect ratio for each possible slice that extends from a given vertex, wherein the aspect ratio for a slice is the slice length divided by a smaller of two resulting widths on either side of the slice,
- selecting the slice with a smallest aspect ratio, and
- applying the slice with the smallest aspect ratio to the polygon, wherein selecting the slice with the smallest aspect ratio avoids slices that create extreme aspect ratios.
Dependencies are inferred from the claim text.