Patent ID: 6501083
Filing Date: 2002-12-31
Classification: G03F,H01J

Abstract:
In a microlithography method in which a pattern defined on a reticle is transferred to a sensitive substrate using an energy beam, a method for determining a cumulative dose of exposure energy received by exposed portions of the sensitive substrate, the method comprising:(a) in a first-level region of the reticle defining multiple pattern elements with respect to which cumulative exposure dose is to be determined, initializing a total cumulative dose for the region to zero, and selecting an evaluation point in the region at which cumulative exposure dose is to be calculated; (b) dividing the region in a branching manner into a second level of subregions each having a respective reference point from which distance measurements concerning the subregion are to be taken; (c) if a subregion has a size parameter that, in a ratio to a distance between the respective reference point and the evaluation point, is greater than a specified value &phgr;, then (i) not subdividing the subregion, (ii) converting any pattern elements located in the subregion into at least one corresponding representative figure, (iii) based on the representative figure(s) in the subregion, calculating a contribution of the subregion to the cumulative exposure dose at the evaluation point, and (iv) adding the contribution to the total cumulative dose for the evaluation point in the region; (d) if a subregion contains a number of pattern elements that is no greater than a specified number m, then (i) not subdividing the subregion, (ii) regarding the pattern element(s) in the subregion as its own respective representative figure, (iii) based on the representative figure(s) in the subregion, calculating a contribution of the subregion to cumulative exposure dose at the evaluation point, and (iv) adding the contribution to the total cumulative dose for the evaluation point in the region; and (e) if a subregion does not satisfy (c) or (d), then subdividing the subregion in a branching manner into a next-lower level of subregions, each next-lower-level subregion having a respective reference point from which distance measurements concerning the subregion are to be taken, and repeating steps (c) and (d) for each of the next-lower-level subregions; and (f) after exhaustively subdividing the region per steps (c)-(e), then regarding a resulting cumulative exposure dose as the cumulative exposure dose for the evaluation point in the region.