Mask based structuring in excimer laser applications is costly if mask with a small ratio of the hole pattern area compared to the whole illuminated area are used. In this case, the major part of the laser beam is reflected or absorbed at the mask. The herein presented system shapes the reflected part of the beam and guides it onto the mask again. This principle has been realized for up to eight irradiations of the mask. In order to achieve high quality ablation result both the beam divergence as well as the homogeneity play an important role. Therefore, a special homogenizer was developed which converts the excimer laser beam efficiency into a flat-top profile with negligible influence on the beam quality. The achieved optical resolution keeps within 2 $mu@m and the homogeneity is sufficient to achieve nearly the same structure quality over the entire image field. Providing that the transmitting areas of the mask do not exceed a few per cent of the total irradiated area. An efficiency enhancement by more than a factor of five was achieved for eight mask irradiation passes compared to a single irradiation.
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机译：基于掩模的基于准分子激光器应用的结构是昂贵的，如果使用与整个照明区域相比具有小的孔图案区域的比率小的掩模。在这种情况下，激光束的主要部分在掩模处被反射或吸收。本文提出的系统将光束的反射部分成形并再次将其引导到掩模上。这一原则已经实现了最多八个掩模照射。为了实现高质量的消融结果，梁发散以及均匀性起着重要作用。因此，开发了一种特殊的均化器，该均化器将准分子激光束效率转换为平板轮廓，对光束质量的影响可忽略不计。实现的光学分辨率在2 $ MU @ M内保持，并且均匀性足以通过整个图像场实现几乎相同的结构质量。提供掩模的透射区域不超过辐照区域的几分之额。与单一照射相比，八个掩模辐射通过效率增强超过五个倍数。
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