【作者】 刘勋；

【导师】 左铁钏；

【作者基本信息】 北京工业大学 ， 光学， 2008， 硕士

【摘要】 在MEMS技术中,准分子激光微细加工技术是一项具有发展潜力的微加工手段。在利用准分子激光进行掩模光刻的试验中,分辨率是决定曝光系统性能的关键因素,不断提高光刻分辨率一直是人们努力解决的问题。其中,掩模光刻系统中光能分布的均匀性是很重要的。本文在了解目前常用的几种准分子激光匀束的方法后,针对实验室拥有的准分子激光器的光束特性和实际用途,提出以二元光学理论为基础,运用微电子加工技术,设计并且制作了应用于准分子激光波面整形的菲涅尔波带透镜。论文首先从理论上证明了二元光学元件(BOE)对激光波面的整形作用。使用MATLAB?编写了基于盖师贝格-撒克斯通(Gerchberg-Saxton)算法的仿真模拟软件,证实了纯相位元件对波面的整形作用。进而,根据二元光学理论设计了均匀器。选择透镜的基本单元为菲涅尔波带片,元件结构为单层复眼形式。为了和实验室已经拥有的准分子激光掩模光刻光路相容,确定元件有效尺寸为33mm×33mm,阵列数目为80×80个,台阶数为8,主焦距为16.0mm,单元孔径之为0.4125mm。因为KrF准分子激光处于紫外波段,所以选择石英材料(JGS1)作为透镜材料。在制作元件的过程中,首先编写程序计算了单元阵列的各个波带环的半径值,并且根据计算数据,使用LEDIT软件绘制了三块掩模版,并且加入相应的对准标记。紧接着,经过试验反复摸索,得到对石英材料光刻的最佳曝光时间为13s,同时研究了等离子体刻蚀的参数选择问题,比如刻蚀速率的测定和刻蚀时间的确定。根据元件结构的要求,确定刻蚀量的大小,进一步确定了每一次刻蚀的时间。最终确定试验参数:曝光时间为13s,显影时间60s,定影时间30s,使用气体为CHF3:180sccm,SF6:60sccm;三次刻蚀的时间分别为T1=9min,T2=4.5min,T3=2.25min;刻蚀速率为V=50nm/min。对制作完成的元件,使用显微镜、三维轮廓仪和电镜来观察它的形貌。为了更好地了解它的工作性能,我们测量了它的能量透过率,并且和现有的石英棒阵列进行比较,原均束器的能量透过率约为77%,完成的二元光学菲涅尔均束器的能量透过率约为85%,有了显著提高。对它的均匀性作了进一步考察,得到在X和Y方向的能量分布。使用在掩模光刻光路中,可以明显看到其对能量的均匀化作用,并且进行了曝光试验。更多还原

【Abstract】 In MEMS technology, excimer laser micro-processing is a potential for the development of micro-machining tools. In the masking photolithography, the resolution is the key factor in system’s performance, and continuously improvement of photolithography resolution has been made efforts to solve the problems. In the masking photolithography system, the uniformity of the distribution of light is very important. Based on the current methods used in excimer laser, we put up the idea that using the binary optical theory to design a BOE for shaping the wave of excimer laser by employing the microelectronic processing techniques, in view of the laboratory’s actual use.In this paper, we testified the function of BOE for shaping the wave, and using MATLAB? software to compile the Gerchberg-Saxton algorithm, which confirmed the function of the pure-phase components for wave shaping.Furthermore, we designed the beam splitter in accordance with the binary optical theories. The basic unit is the Fresnel zone plate, and the structure is the single-layer compound eyes. Based on the actual application, we determined the parameters as follows: the effective size of BOE is 33 mm×33mm, the number of arrays is 80×80, the step number is 8, the main focal length is 16.0 mm, the cell aperture is 0.4125 mm. The quartz (JGS1) was selected as the material, because the wave length of KrF excimer laser is in the ultraviolet band.In the process of BOE’s fabrication, we calculated the values of various radiuses, firstly. In the light of calculated data, we used the software LEDIT to draw the three masks, and add the corresponding alignment markers. Immediately, the optimal exposure time toward JGS1 is determined as 13s after many experiments, in the meantime, the parameters of the plasma etching are confirmed. According to the requirements of structural components, we obtained the value of etching depth and further determined the etching time for each mask.Final experimental parameters: the exposure time is 13s, the development time is 60s, fixing time is 30s, the gases used are CHF3: 180sccm, SF6: 60sccm; three etching times are T1 = 9min, T2 = 4.5min, T3 = 2.25min, respectively; etching rate is V = 50nm/min.We employed the microscopes and 3D contourgraph to observe the patterns of finished components. In order to understand its performance better, we measured the energy transmissivity, and make it have a comparison with the existing quartz rod arrays. The energy transmissivity of original quartz rod arrays is about 77%, and that of the binary optical Fresnel lens is about 85%, with a significantly increase. The uniformities of BOE in X and Y directions were measured respectively. In the use of masking photolithography, we can clearly see that the element play a role in making the uniformity of excimer laser’s energy, and have done some experiments.更多还原