Patent ID: 9709893
Date: 2017-07-18
CPC Classifications: G03F

Claim:
1. An exposure method comprising: providing a substrate having a layer of photoresist thereon; designing a target pattern to be formed on the substrate; creating a first dose map of first dose values, wherein the first dose values are representative of doses of energy of beams emitted by a light source of an exposure apparatus, and the first dose map includes a representation of a corrected version of the target pattern; creating a second dose map of second dose values, different from the first dose values, wherein at least some of the second dose values correspond to values of doses of energy produced by overlapping ones of the beams; controlling the light source of the exposure apparatus to irradiate respective regions of the layer of photoresist in such a way that said respective regions are exposed to doses of energy having values based on the second dose values to thereby alter said regions of the layer of photoresist; and determining a cost function before or after obtaining the first dose map, wherein the cost function is converted into a minimum cost function by repeatedly calculating the first dose map and the second dose map, the second dose map calculated by the minimum cost function, wherein the cost function comprises a constraint term comprising input dose values of a first exposure pattern and minimum dose values given to a minimum line width of the first exposure pattern, and wherein the constraint term comprises a first constraint term including a fixed input dose value which is provided to the first exposure pattern, and a second constraint term providing a second dose value corresponding to a minimum dose value at the minimum line width.