High efficiency regulation method to generate an illumination source by adopting the micromirror array in DUV lithography
Abstract
Source and mask optimization (SMO) is an important lithography resolution enhancement technique for 22 nm technology nodes and beyond in lithography. This technique generates freeform sources by adjusting the inclination angle of the micromirror array (MMA). In this paper, a high efficiency regulation method to generate an illumination source by adopting the micromirror array in DUV lithography is proposed. The number and inclination angles of micromirrors required for adjustment to convert the initial source into any illumination source are quickly and accurately obtained by using the proposed method. The illumination source is obtained on the pupil plane by adjusting the inclination angles of some micromirrors. The simulation results show that the initial source is converted into another illumination source with different complexities by adjusting some micromirrors. Compared with the traditional MMA allocation method, when the initial source is the freeform source, the regulation efficiency of micromirrors has been improved by at least 20%. The method reduces the regulation time of micromirrors and the number of micromirrors required for adjustment. Moreover, the number of micromirrors required for adjustment is positively correlated with the coherence coefficient. The results illustrate that this method is effective and has significant engineering implications.