基于365nm LED光源的无掩模数字光刻特性研究

发布时间：2018-08-25 17:41

【摘要】：自从1958年,美国第一次成功把光刻技术应用于集成电路制造中,光刻技术就在不断发展。光刻技术是用于制作半导体器件和集成电路的,决定着半导体产业的发展。随着光刻线宽精度越来越高,传统有掩模光刻的制造成本也越来越高。基于DLP投影技术的数字光刻技术,使用DMD作为空间光调制器代替掩模板。由于其不需要每次针对光刻图形制造掩模板,从而降低了光刻中的制造成本,并且面扫描的方式能大大提高生产效率,能实现实时、高效率和低成本的图形转移。传统光源如高压汞灯、准分子激光器等,这些光源,有的价格昂贵,有的不够环保,有的不够节能,另外它们体积都比较大,很难实现光刻机照明系统的小型化。而新一代照明光源紫外发光二极管(UV-LED)不仅具有长寿命、低能耗、高光效,并且安全性好、性能稳定等优点。相较于其他传统光源,UV-LED厘米量级的光源尺寸使其成为小型照明系统的理想光源。本文对基于UV-LED光源的数字光刻的光学系统以及动态掩模DMD分别进行了研究。其中光学系统主要为两部分,第一部分是照明系统,包括光源、准直单元和匀光单元,另一部分则是投影系统即投影镜头。首先,简述了DMD的发展过程、结构和工作原理。然后在对DMD的灰度、结构和光学特性分别进行了研究。其次,我们研究了照明系统。明确了UV-LED光源的优势,研究了UV-LED光源的特性。之后分析了常用准直方式的优劣处,介绍了使用柯勒照明方式下的两种常用匀光器件,了解了照明系统的关键参数。再者,选择并采取了透镜作为准直单元、复眼透镜作为匀光单元。在这种情况下,利用复眼透镜对365 nm LED进行了匀光设计,复眼透镜阵列采用近六边形的排列方式,其能基本覆盖圆形光。近六边形阵列相对于方形结构能减少无效透镜数量,因此能更有效地利用透镜发挥匀光效能,并且能减少小透镜的使用数量,降低设备成本。之后用软件分别仿真了采用近六边形、9×9方形透镜的照明系统,并对比了其照度图,结果表明使用近六边形阵列的照明系统照度更为均匀。最后,对投影镜头的特性进行了研究,根据照明系统和DMD利用Zemax软件设计了一组相匹配的投影镜头,其分辨率可以达到2μm,数值孔径NA=0.158,放大倍率为-0.15,光程差小于λ/20,畸变在0.016%以内。之后用近六边形阵列设计的照明系统与数字微反射镜(DMD)、光刻镜头相结合,进行了2μm精度的数字光刻实验,其像面照度均匀,线条清晰且无任何断线,验证了所设计的近六边形排列照明系统和投影镜头的有效性。
[Abstract]:Since 1958, the United States successfully applied lithography technology in integrated circuit manufacturing, lithography technology has been developing. Photolithography is used to fabricate semiconductor devices and integrated circuits, which determines the development of semiconductor industry. With the increasing precision of line width, the manufacturing cost of traditional mask lithography is higher and higher. Digital lithography based on DLP projection technology, DMD is used as spatial light modulator instead of mask. Because it does not need to fabricate mask for lithography every time, it reduces the manufacturing cost in lithography, and the way of surface scanning can greatly improve the production efficiency and realize real-time, high efficiency and low cost graphics transfer. Traditional light sources such as high pressure mercury lamps excimer lasers and so on some of these sources are expensive some are not enough environmental protection some are not enough energy saving in addition they are all relatively large it is difficult to realize the miniaturization of the lighting system of lithography machine. The new generation of ultraviolet light emitting diode (UV-LED) not only has the advantages of long life, low energy consumption, high light efficiency, but also good security and stable performance. Compared with other traditional light sources, UV-LED centimeter light source size makes it an ideal light source for small lighting systems. The optical system of digital lithography based on UV-LED light source and dynamic mask DMD are studied in this paper. The optical system consists of two parts, the first part is the illumination system, which includes the light source, the collimation unit and the uniform light unit, and the other part is the projection system, that is, the projection lens. Firstly, the development process, structure and working principle of DMD are briefly described. Then, the grayscale, structure and optical properties of DMD are studied. Secondly, we studied the lighting system. The advantages of UV-LED light source are clarified and the characteristics of UV-LED light source are studied. After that, the advantages and disadvantages of common collimation methods are analyzed, and two kinds of common uniform light devices under Kohler illumination mode are introduced, and the key parameters of lighting system are understood. Furthermore, the lens is selected and adopted as collimation unit, and the compound eye lens is used as the uniform light unit. In this case, a uniform light design for 365 nm LED using a compound lens is carried out. The array of compound eye lenses is arranged in a nearly hexagonal manner, which can basically cover the circular light. The near-hexagonal array can reduce the number of invalid lenses compared with the square structure, so it can make use of the lens more effectively, reduce the number of small lenses and reduce the cost of equipment. After that, the illumination system with 9 脳 9 square lens is simulated by software, and the illumination diagram of the system is compared. The results show that the illumination of the illumination system using the near hexagonal array is more uniform. Finally, the characteristics of projection lens are studied. According to the illumination system and DMD, a set of matched projection lenses are designed by using Zemax software. The resolution of the lens can reach 2 渭 m, the magnification ratio of numerical aperture NA=0.158, is -0.15, the optical path difference is less than 位 / 20, and the distortion is less than 0.016%. Then the illumination system designed with nearly hexagonal array is combined with the (DMD), lithography lens of digital microreflector, and the experiment of digital lithography with 2 渭 m precision is carried out. The illumination of the image plane is uniform, the lines are clear and there are no broken lines. The effectiveness of the designed nearly hexagonal arrangement illumination system and projection lens is verified.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN305.7

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