准分子激光的波长短、带宽窄。这使全熔石英制作的高数值孔径投影物镜的应用成为可能，促使光刻投影曝光系统的分辨力由0.5μm迅速提高到38nm，并向28nm挺进。而且大功率的准分子激光器增加了投影曝光系统的输出光通量，缩短曝光时间，提高生产效率。对300mm硅片，ASML公司最新的浸没式光刻机TWINSCAN NXT 1950i的生产效率已达到175wph。这些优点促使高分辨力的光刻投影曝光系统均采用准分子激光器作为光源。
|英文摘要: ||The laser projection system of step & scan exposure tool and laser projector display etc.，which uses laser as light scource, plays an important role in industry and living. Illuminator is one of essential subsystems which matches the light from laser scource to the projector, and it provides light power with projectors by reshaping the laser beams and illuminating the mask or the light valves to form expected light power distribution.
The color purity of laser is high because the line shape of laser spectral is a narrow line. There are plenty of spectral lines in the visible range whose light output is powerful. A laser projector display can present more realistic natural color on a large screen if choosing the laser sources reasonably. It will enable optical projector display technology and system to evolve revolutionarily.
Similarly, an excimer laser wavelength is short, which the spectral width is narrow. Thus, it is possible that the high NA all fused silica projector lens can be applied to lithography system. The resolution of lithography system has been improved from 0.5μm to 38nm. It will be up to 28nm in the next generation. The high light power of excimer laser shortens the exposure time, while increases the lithography system throughout. TWINSCAN NXT 1950i step & scan tool produced by ASML can expose 175 pieces 300mm wafers per hour.
But the collimated laser beams are coherent. Speckle can be evoked by scattering the beam. The illuminace will not be uniform when a laser beam is used directly.. Since the laser shortage has to be overcome, this paper focused on the ways how to illuminate uniformly with a laser beam and how to restrain the speckle. First, it is discussed the optical integrator in detail and how to form homogeneous illuminance after ignoring beam coherence. Second, it is focused on the restrain of the speckle induced by the high coherence of laser beam.
After ignoring beam coherence, illuminators are described in detail. The ways how to illuminate uniformly were found out. Both the fly-eye and the optical tunnel were studied particularly. A specific radiation source matched with the fly-eye or the optical tunnel was constructed. The radiation source is formed through inserting a specific diffuser into a right place in two kinds of the uniformity illuminators composed by the fly-eyes or the optical tunnel respectively. The simulation results show that the above illumination systems can form perfect unform light power distribution and indicated that 10 per errors of the radiation source affected little.
It was studied that a polarization light's refraction and total reflection on the interface between the air and fuzzed silica. It indicated that the effect of the fly-eye on depolarization of the light beam can be neglected when light aperture angle is less than 10º, while the optical tunnel depolarizes the light greatly.
It was discussed how to restrain the speckle which was induced by scattering a coherent laser beam. The speckle was classified into once scattering speckle, which appears on the screen, and twice scattering speckle, which emerges on the detectors such as the retina etc.. Both the once scattering speckle and twice scattering speckle can be restrained by random phase plates modulating the laser beams. It has been confirmed by the simulations and experiments data.
At last, two illuminator examples were listed in the paper. The achievements would become a good reference for illuminator designers in future.|
|Appears in Collections:||光电技术研究所博硕士论文_学位论文|
|File Name/ File Size
廖志杰. 激光投影系统中的均匀照明研究[D]. 光电技术研究所. 中国科学院光电技术研究所. 2009.