Constrained pupil balance compensation for specific lithographic illuminator settings.

Pupil energy balances have always been considered significant elements for emersion lithography generally due to the large angle of incidence and offset imaging field. Those imbalances impact on exposure uniformity and decay pattern resolution. To overcome such shortcomings, a study on pupil compensation is discussed in this manuscript. A computational method based on a constrained optimization solution is proposed. By using a self-designed optical model of a zoomed system incorporating axicon lenses, a series of computations are developed and discussed. Also, the validity of our compensation method has been fully verified by simulations under multiple illumination settings.

High-performance laser projection display illumination system based on a diffractive optical element.

Lasers have been regarded as the potential illumination source for next generation projectors. With the additional feature of coherency, diffractive optical elements (DOEs) become available in the illumination light path. DOEs in laser projection display systems add strong beam-shaping ability, good uniform performance and small size, which makes it is possible to realize efficient and uniform illumination on a spatial light modulator (SLM). Moreover, it is helpful for the simplification and compactness of illumination optics. This paper proposed what we believe is a novel RGB laser projection display illumination system based on a DOE, which used the DOE and optical path compensation system (OPCS) as the beam-shaping and relay system (BSRS), instead of a light pipe and relay lens group in the conventional laser projection display illumination system. We designed the DOE and established the simulation model of the illumination system. The simulation results show that the new illumination system is simple and compact, the illumination uniformity is more than 90%, the illumination efficiency of RGB illumination in BSRS is more than 75%, and the numerical aperture (NA) of the illumination beam is about 0.01.

Computational method for simulation of thermal load distribution in a lithographic lens.

As a crucial step for thermal aberration prediction, thermal simulation is an effective way to acquire the temperature distribution of lenses. In the case of rigorous thermal simulation with the finite volume method, the amount of absorbed energy and its distribution within lens elements should be provided to guarantee simulation accuracy. In this paper, a computational method for simulation of thermal load distribution concerning lens material absorption was proposed based on light intensity of lens elements' surfaces. An algorithm for the verification of the method was also introduced, and the results showed that the method presented in this paper is an effective solution for thermal load distribution in a lithographic lens.