【作者】 张山；

【导师】 谭久彬；

【作者基本信息】 哈尔滨工业大学 ， 光电信息技术与仪器工程， 2010， 博士

【摘要】 激光直写技术无需掩模、加工灵活,可制作出边缘平滑的复杂特征结构,是制作衍射微结构光学元件的重要技术手段之一。随着科学技术的发展,对微结构光学元件的大口径和精细化的需求日益迫切,这就要求更高的激光直写精度。曝光是激光直写技术的重要工序,对加工精度起着决定性的作用,但目前还存在三个与此工序相关且不够完善需要解决的问题:曝光模型不够准确、邻近效应校正方法不够完善和定位精度不高,这些因素不利于激光直写技术的实验研究和加工质量的提高。课题“影响直角坐标激光直写曝光质量的若干关键技术研究”的目的是对影响直角坐标激光直写曝光质量的上述三个关键问题进行研究,在深入分析直写曝光过程的基础上,建立与实际工况相符的直角坐标激光直写动态曝光模型,完善邻近效应校正方法,以及探讨降低宏微系统定位噪声的方法,为高加工精度的激光直写机的研制提供理论依据和技术基础。本课题的研究可为大口径、复杂结构衍射微光学元件的加工提供可靠的模型和技术。本文为了更加精确地预测直角坐标激光直写获得的光刻线条质量,建立了一种兼顾胶层的光吸收特性、直写光束的高斯分布特征以及直写光束与胶层的相对运动的直角坐标激光直写动态曝光模型,据此模型分析了直写速度和直写光功率的变化对光刻胶内线条线宽和侧壁角的影响,从而可以创建满足线条质量要求的直写系统的加工工艺窗,为开展激光直写光刻实验提供了理论指导。为了有效校正激光直写中的邻近效应,提出了声光调制器低分辨力时邻近效应的校正方法,该方法基于误差校正迭代方法,先以虚拟的高分辨力声光调制器对直写图案进行校正,再对各误差区域重心的最邻近光点的曝光量数据进行调制寻优,可有效克服误差校正迭代方法不能以低分辨力声光调制器校正直写图案以及寻优不彻底的缺点。为了合理选择耦合阻尼抑制宏微系统中的定位噪声,基于并行双伺服控制策略建立了包含耦合阻尼的宏微系统控制模型,研究分析了耦合阻尼的作用规律,从而揭示了耦合阻尼对噪声传递和宏、微工作台动态特性等的影响,为宏微系统采用耦合阻尼方式改善定位稳定性、达到纳米级的定位噪声提供了一定的理论指导。最后对课题所研究的若干关键技术进行了实验验证。首先,对所提出的声光调制器低分辨力时邻近效应的校正方法进行了实验验证。实验表明:以“L”直写图案为例,相比在声光调制器低分辨力情况下无法对直写图案优化校正的误差校正迭代方法,用本文所提方法能对直写图案进行优化校正,并使图案误差相对于原始误差减小了70.88%。然后,研制了宏微系统的耦合阻尼器,完成了宏微系统的搭建、调试和性能测试,并就宏微系统控制模型的有效性和耦合阻尼的作用效果进行了实验验证。实验表明:在控制参数不变的条件下,实验结果与所推导的宏微系统中的耦合阻尼特性一致,且增加阻尼系数为293.78N/(m/s)的耦合阻尼器后,本文所研制的宏微系统的定位噪声由80nm(峰峰值)降为60nm(峰峰值)。更多还原

【Abstract】 Laser direct writing (LDW) is one of the important technologies used to fabricate diffractive micro-optical elements for its flexibility, simplicity and ability to make complex feature structure with smooth edge. With the development of science and technology, the urgent requirements for large aperture and refinement of micro-optical elements make the writing accuracy of LDW get more and more strict. Exposure is one of the most important working procedures, which plays a decisive role in the processing accuracy. However, there still exist three shortcomings relevant to exposure process such as low accurate exposure model, inadequate perfection of optical proximity correction method and poor positioning precision, which block the experimental research and processing quality improvement of LDW.The subject“Study of Key Techniques Impacting on Exposure Quality of Laser Direct Writing in Cartesian Coordinate”is to do research on the key techniques relevant to exposure quality, and focused on building the dynamic exposure model of actual condition, improving the optical proximity correction method, and discussing the method of reducing the positioning noise of coarse-fine driving table, which provides a powerful theoretical and technical basis for high precision LDW. The research of this subject also provides reliable models and techniques for making large aperture and complex structure diffractive micro-optical elements.In order to predict the laser direct writing quality in Cartesian coordinate, a new dynamic exposure model is established by taking into consideration the effect of the photoresist absorbing beam energy, the Gaussian attribute of the writing beam and the relative movement between writing beam and photoresist, to describe the influence of a change in writing velocity and writing power on the line width and sidewall angle in the photoresist, so that critical dimension process window can be obtained to provide a theoretical basis for LDW experiment.Correction method with low resolution acoustooptic modulator is proposed to efficiently correct the optical proximity effect in laser direct writing. Firstly, based on Iterative Error-Correction Method (IECM) proposed by Rajesh Menon, one virtual high resolution acoustooptic modulator is used to correct the direct writing pattern, then the exposure data of spots nearest to each error area barycenter are modulated, and the above steps help IECM correct the optical proximity with low resolution acoustooptic modulator and make a thorough optimization.In order to reasonably choose coupling damp to suppress the positioning noise of coarse-fine stage, model of dual stage with coupling damp is established based on parallel dual servo control and used to study the effect law of coupling damp, which reveals the effect of coupling damp on noise transmission and dynamic characteristic of each stage, and provides theoretical basement for the improvement of positioning stability and the accomplishment of nano-precision positioning with damp.In the last section of the paper, several key techniques in this subject have been studied through experiments. Firstly, the optical proximity correction method with low resolution acoustooptic modulator has been carried out through experimental study. Experimental results indicate that, taking“L”design pattern as example, compared with IECM unable to correct the direct writing pattern with low resolution acoustooptic modulator, the proposed method in this subject can correct the direct writing pattern, which decreases pattern error value by 70.88% relative to the initial error value. Then, the coarse-fine stage with damping oil damper has been developed, and the validity of coarse-fine system model and the action effect of coupling damp has been tested through experiments. Experimental results indicate that, based on the developed system and the same control parameters, the experimental coupling damp characteristics agree with the theoretical results, and the coupling damper with damping coefficient 293.78 N/(m/s) suppresses the positioning noise of coarse-fine driving control system from 80nm(pk-pk) to 60nm(pk-pk).更多还原