【作者】 魏石铭；

【导师】 李立峰；

【作者基本信息】 清华大学 ， 光学工程， 2010， 博士

【摘要】 衍射度量术是一类通过对周期性结构远场衍射光特性的分析来精确测量周期性结构形貌参数的方法。这类方法具有非接触、无损伤、快速响应等优点,适用于各种在线、离线的测量环境。本论文围绕着衍射度量术这一核心方法,对不同类型的光刻胶掩模光栅、小阶梯光栅,设计了4种在线监测与离线检测光栅形貌参数的方法。并在其中一些方法的辅助下,成功地制作出了局部衍射效率和杂散光性能达到商用光栅水平的小阶梯闪耀光栅母光栅。针对铬膜上的驻波形光刻胶光栅,本论文使用多波长衍射度量术和人工神经网络技术相结合的方法对其形貌参数进行了测量,并提出了通过选择光束入射条件来优化方法的思路。实验结果表明,这一方法对1480线/mm驻波形光栅栅脊高度和占宽比的测量误差分别为18nm和1.3%。针对透明基底上的矩形光刻胶掩模光栅,本论文提出了利用其显影监测曲线的极值和0、-1级透射衍射级次同时监测的光栅参数显影实时监测方法,并通过实验验证了该方法的可行性。实验结果表明,这一方法对1200线/mm矩形光刻胶掩模光栅栅脊高度和占宽比的控制精度分别达到了22nm和1.7%。同时,本论文还设计了一种离线测量透明基底上矩形光刻胶掩模光栅形貌参数的方法,并通过实验验证了此方法的精度,使用这种方法可以在显影后对掩模光栅的形貌参数进行再次确认。针对使用矩形光刻胶掩模和离子束掠入射刻蚀小阶梯介质光栅的刻蚀工艺,本论文提出了一种在线监测刻蚀终点的方法,并通过实验验证了该方法的可行性,其成功率可达60%以上。在光栅制作工艺方面,本论文发展了全息法制作小阶梯光栅中离子束刻蚀工艺的过程模型,提出并说明了对掩模形貌和刻蚀时间进行精确控制的必要性。在本论文中,我们对小阶梯光栅的各步制作工艺进行了较为深入的探索,通过大量的工艺实验,确定了有效的基片清洗步骤、匀胶工艺流程、匀胶后烘参数、掩模硬烘参数等关键的工艺细节。更多还原

【Abstract】 Scatterometry, which is based on the measurement of far-field diffraction responses of periodic structures, is a sort of methods for accurate grating topography extraction. The non-contact, nondestructive and rapid-response features of scatterometry make it preferred in all kinds of online and offline applications. By use of scatterometry, we designed four kinds of online and offline grating profile measurement methods for different types of photoresist gratings and echelette gratings in this dissertation work. With some of the above measurement methods, we fabricated some echelette gratings whose local area diffraction efficiency and stray light level meet the commercial grating standards.For photoresist gratings with wavy sidewall profiles on a chrome film, we employed a profile measurement method, which is based on the combination of multi-wavelength scatterometry and artificial neural network, to determine their critical dimensions. From the experimental results of 1480 lines/mm gratings, we verified the precisions of this method for grating ridge height and duty cycle are about 18nm and 1.3%, respectively.For rectangular photoresist gratings on transparent substrates, we presented an in situ monitoring method during the development process. By use of the extreme values of monitoring curves of both the 0th and the -1st transmission orders, we determined the two profile parameters at the same time. From the experimental results, we verified the validity of this in situ monitoring method. For 1200 lines/mm gratings, the measurement precisions of this method for height of grating ridges and duty cycle of gratings are about 22nm and 1.7%, respectively. Meanwhile, in this dissertation we designed another offline measurement method to ensure the grating profile parameters got from the in situ monitoring method was correct, and tested the accuracy of this method.For ion-beam etching process of echelette gratings by use of rectangular-profile photoresist masks and grazing ion-beam incidence, we designed an online endpoint detection method. By experimental verifications, the success rate of this method is above 60%.The ion-beam etching process model of echelette grating fabrication is improved by accurate control of photoresist grating profiles and etching time. From a large number of experiments, we determined the technical details of echelette grating fabrication, such as the way of grating substrate cleaning, the processing steps of photoresist spinning, and optimized parameters of postbake and hardbake.更多还原