Mask process correction methods and methods of fabricating lithographic masks using the same
Methods of fabricating lithographic masks include performing mask process correction (MPC) on a mask tape out (MTO) design layout. Performing MPC may include identifying a plurality of unit cells (each being iterated in the MTO design layout and including a plurality of curve patterns), and performing model-based MPC on at least one of the plurality of unit cells. These methods may further include performing electron beam exposure based on the MTO design layout on which the MPC is performed. The performing model-based MPC on at least one of the plurality of unit cells may be based on at least one of an aspect ratio, sizes, curvatures of curved edges, density, and a duty of the plurality of curve patterns.
1 . A method, comprising:
performing mask process correction (MPC) on a mask tape out (MTO) design layout, said MPC including: (i) identifying a plurality of unit cells, each being iterated in the MTO design layout and the plurality of unit cells including a plurality of curve patterns, convex patterns, concave patterns, and linear patterns, and (ii) performing model-based MPC on each of the plurality of unit cells;
wherein the plurality of curve patterns are arranged to constitute rows and columns, and a curved edge of each of the plurality of curve patterns has an elliptical shape;
wherein performing MPC further includes applying a single bias for to the plurality of curve patterns with the elliptical shape calculated based on one of the plurality of unit cells, to each of the plurality of unit cells;
wherein each of the plurality of curve patterns with the elliptical shape includes first and second vertices on a major axis of the curved edge, and third and fourth vertices on a minor axis of the curved edge;
wherein applying the single bias includes applying the single bias to the first to fourth vertices to determine first to fourth biased vertices, which are respectively corrected positions of the first to fourth vertices in order for a respective biased curve pattern that is constrained to have matching curvature relative to the curved edges of a corresponding curve pattern with the elliptical shape during said applying the single bias, and
wherein the method further comprises:
fabricating a lithographic mask by performing electron beam exposure based on the MTO design layout having only the single bias.
2 . The method of claim 1 , wherein said performing model-based MPC on each of the plurality of unit cells is based on at least one of an aspect ratio, sizes, curvatures of curved edges, density, and a duty of the plurality of curve patterns.
3 . The method of claim 1 , wherein said performing MPC further comprises determining biased curved edges by modifying the plurality of curve patterns with the elliptical shape based on the first to fourth biased vertices.
4 . The method of claim 3 , wherein the determining of the biased curved edges is based on curvatures of the plurality of curve patterns with the elliptical shape, before performing MPC.
5 . The method of claim 1 , wherein the MTO design layout is generated by inverse lithography technology (ILT).
6 . The method of claim 1 , wherein the plurality of curve patterns with the elliptical shape correspond to contacts formed on a wafer.
7 . A method, comprising:
performing mask process correction (MPC) on a mask tape out (MTO) design layout, said MPC including: (i) identifying a plurality of unit cells, each being iterated in the MTO design layout and including curve patterns, convex patterns, concave patterns, and linear patterns, and (ii) performing model-based MPC on a first one of the plurality of unit cells;
wherein performing MPC further includes applying a single bias to each of the plurality of curve patterns associated with the first one of the plurality of unit cells;
wherein each of the plurality of curve patterns includes a respective pair of first and second vertices on a curved edge of a corresponding curve pattern;
wherein applying the single bias includes applying the single bias to at least one of the pairs of first and second vertices to determine a corresponding pair of first and second biased vertices, which are corrected positions of the corresponding first and second vertices on a respective biased curve edge of a biased curve pattern that is constrained to have matching curvature relative to the curved edge of the corresponding curve pattern during said applying the single bias, and
wherein the method further comprises:
fabricating a lithographic mask by performing electron beam exposure based on the MTO design layout having only the single bias.
8 . The method of claim 7 , wherein a factor of the model-based MPC includes a curvature, a duty, and a size of each of the curve patterns, the convex patterns, the concave patterns, and the linear patterns.
9 . The method of claim 7 , wherein, in the performing of the MPC, a bias table for inflection points of each of the curve patterns, the convex patterns, the concave patterns, and the linear patterns is generated based on the model-based MPC for any one of the plurality of unit cells.
10 . The method of claim 9 , wherein said performing MPC further comprises determining biased inflection points by applying the bias table to the inflection points of each of the curve patterns, the convex patterns, the concave patterns, and the linear patterns of each of the plurality of unit cells.
11 . The method of claim 10 , wherein said performing MPC further comprises correcting the curve patterns, the convex patterns, the concave patterns, and the linear patterns of each of the plurality of unit cells based on the biased inflection points and curvatures of the curve patterns, the convex patterns, the concave patterns, and the linear patterns.
12 . A method, comprising:
performing mask process correction (MPC) on a mask tape out (MTO) design layout, said MPC including: (i) identifying at least one unit cell containing a plurality of curve patterns, convex patterns, concave patterns, and linear patterns, therein, and (ii) performing model-based MPC on the identified at least one unit cell;
wherein performing MPC further includes applying a single bias to each of the plurality of curve patterns associated with the at least one unit cell;
wherein each of the plurality of curve patterns includes a respective pair of first and second vertices on a curved edge of a corresponding curve pattern; and
wherein applying the single bias includes applying the single bias to at least one of the pairs of first and second vertices to determine a corresponding pair of first and second biased vertices, which are corrected positions of the corresponding first and second vertices on a respective biased curve edge of a biased curve pattern that is constrained to have matching curvature relative to the curved edge of the corresponding curve pattern during said applying the single bias, and
wherein the method further comprises:
fabricating a lithographic mask by performing electron beam exposure based on the MTO design layout having only the single bias.
13 . The method of claim 12 , wherein the biased curve edge of the biased curve pattern is determined using an interpolation operation.