Method for reticle enhancement technology of a design pattern to be manufactured on a substrate
Methods for reticle enhancement technology (RET) for use with variable shaped beam (VSB) lithography include determining an initial mask pattern from a desired pattern for a substrate; calculating a first substrate pattern from the initial mask pattern; determining an initial set of VSB shots that will form the initial mask pattern; calculating a simulated mask pattern from the initial set of VSB shots; calculating a second substrate pattern from the simulated mask pattern; and adjusting the initial set of VSB shots, wherein the adjusting of the initial set of VSB shots creates an adjusted set of VSB shots.
1. A method for reticle enhancement technology (RET) for use with variable shaped beam (VSB) lithography, the method comprising:
determining an initial mask pattern from a desired pattern for a substrate;
calculating a first substrate pattern from the initial mask pattern;
determining an initial set of VSB shots based on the initial mask pattern;
calculating a second substrate pattern from a simulated mask pattern calculated with the initial set of VSB shots;
comparing the first substrate pattern with the second substrate pattern; and
adjusting the initial set of VSB shots until the second substrate pattern and the first substrate pattern are within a predetermined tolerance, creating an adjusted set of VSB shots.
2. The method of claim 1 , further comprising outputting the adjusted set of VSB shots.
3. The method of claim 1 , wherein the adjusting comprises optimizing the initial set of VSB shots for wafer quality, thereby creating an optimized mask pattern.
4. The method of claim 3 , further comprising outputting the optimized mask pattern.
5. The method of claim 1 , wherein the adjusting comprises resizing or moving one or more shots.
6. The method of claim 1 , wherein the adjusting comprises reducing Edge Placement Error between the first substrate pattern and the second substrate pattern.
7. The method of claim 1 , wherein calculating the first substrate pattern and calculating the second substrate pattern comprise lithography simulation.
8. The method of claim 1 wherein the initial mask pattern is curvilinear.
9. The method of claim 1 wherein the initial mask pattern is rectilinear.
10. The method of claim 1 , wherein the determining of the initial set of VSB shots optimizes for mask manufacturability.
11. The method of claim 1 , wherein the determining the initial mask pattern further comprises inverse lithography technology (ILT).
12. The method of claim 1 , wherein calculating the second substrate pattern further comprises calculating the simulated mask pattern from the initial set of VSB shots.
13. The method of claim 12 , wherein the calculating the simulated mask pattern uses a simple mask model.
14. The method of claim 13 , further comprising:
inputting a detailed mask model;
modifying the adjusted set of VSB shots to create a modified set of VSB shots, wherein the modified set of VSB shots complies with the detailed mask model; and
outputting the modified set of VSB shots.
15. The method of claim 14 , further comprising exposing a reticle with the modified set of VSB shots.
16. The method of claim 13 , wherein the simple mask model comprises a single Gaussian distribution.
17. The method of claim 13 , wherein the simple mask model comprises a constant etch bias.