准分子激光刻蚀聚合物制作微光学元件
文献类型：学位论文
| 作者 | 章琳 |
| 学位类别 | 硕士 |
| 答辩日期 | 2001 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 楼祺洪 |
| 关键词 | 准分子激光 聚合物 刻蚀 微衍射光学元件 |
| 中文摘要 | 本文主要描述了两种波长准分子激光消融刻蚀聚合物制作位相光栅，以及准分子激光消融刻蚀某些无机材料的实验研究。实验中使用的两种激光是最典型、最常用的准分子激光：XeCl(波长：308nm，脉冲半高宽：30ns)和ArF(波长193nm，脉冲半高宽：17ns)。准分子激光具有短波长特性，其光子能量高，光子作用在聚合物化学键上能引起化学键的断裂，从而引起聚合物的分解反应，进而形成聚合物的刻蚀。由于聚合物对紫外激光具有强吸收，因此激光穿透深度(定义为吸收系数的倒数)可在亚微米量级。这使得：一、准分子激光刻蚀聚合物具有亚微米深度精度；二、准分子激光刻蚀聚合物具有低阈值特性；三、准分子激光刻蚀聚合物时热分解机制成为主要机制之一。实验中主要研究了两种波长准分子激光对PI(polyimide)、PC(polycarbonate)和PMMA(polymethyl methacrylate)三种常用聚合物的刻蚀，并探讨了数种刻蚀机制。其中308nm准分子激光对PMMA和PC材料的刻蚀性能极差，这主要是因为两种材料对308nm激光的吸收系数很小，约为20cm~(-1)。而308nm准分子激光对PI以及193nm准分子激光对PI和PC具有极佳的刻蚀性能，因为三种情况下材料对激光的吸收系数为10~5cm~(-1)量级。实验表明聚合物的吸收系数对刻蚀性能影响最大。实验中我们采用了多种刻蚀方案，包括采用基于振幅掩模板的投影法、接触法和接近法刻蚀，以及相位板法刻蚀。通过308nm准分子和193nm准分子激光刻蚀通过旋涂法在石英基片上制备的PI薄膜，我们成功的制作了直条光栅和Dammann光栅，并获得了较高的衍射效率。实验表明准分子激光刻蚀PI等聚合物具有微米级分辨率，同时深度精度可达亚微米量级。准分子激光加工无机材料主要为热汽化机制。由于准分子激光的短脉冲特性，消融加工过程中热效应很小，同时材料对紫外光具有强吸收，因此具有较高的加工精度。通过193nm准分子激光切割Si片，我们获得了比YAG激光好的切割边缘。LiNbO_3晶体是最常用的集成光学基质材料，对其进行微细加工是集成光学发展的关键。现行的反应离子刻蚀以及腐蚀加工都无法获得满意的结果。通过193nm激光消融LiNbO_3晶体，我们获得了较高质量的V槽，用于光纤安置和对准。 |
| 英文摘要 | In this paper, the study of fabrication of phase-gratings by two wavelengths excimer lasers ablatively etching polymers, and ablation of some kinds of inorganic materials is mainly described. In the experiments, two kinks of typical and popular excimer lasers are used: XeCl(wavelength:308nm, FWHM:30ns) and ArF(wavelength: 193nm, FWHM: 17ns). Excimer lasers have the advantage of short wavelength, the energy of single photon is relatively high, which is enough to directly break the chemical bonds and cause the decomposition of polymer. And then engender the etching of polymer. Polymers have strong absorptivities to excimer lasers, so the Optical Penetration Depth (defined as the inverse of absorptivity) can reach to the order of submicron. This means that: 1. Etching of polymers by excimer lasers can reach to submicron depth; 2. The threshold of excimers lasers etching of polymers is rather low; 3. Thermolytic mechanism becomes one of the main mechanisms of excimer lasers etching of polymer. Here, three kinds of popular polymers - PI (polyimide), PC (polycarbonate) and PMMA (polymethyl methacrylate) - are studied, and several mechanisms of etching are discussed. Wherein, the etching performances of PMMA and PC by 308nm laser are very poor, the main reason is that both polymers have low absoptivities to 308nm, which are about 20cm~2. But the performances of 308nm excimer laser etching of PI and 193nm excimer laser etching of PI and PC are very good, because in the three cases, the absorptivities are all about the order of 10~5cm~(-1). Our experiments show that the absorptivity of polymer has the greatest influence on etching performance. Several schemes of etching are tested in our experiments, such as projection, contact and near-contact methods which base on amplitude mask, and method based on phase-mask. By 308nm and 193nm excimer lasers etching of thin film of PI on quartz substrate prepared by spin-coating, we successfully fabricated grating and Dammann grating, and relatively high diffraction efficiency is achieved. Our experiments show that excimer laser etching of polymers like PI has definition about the order of micron, and the depth-definition can be the order of submicron. Thermo-evaporation is the main mechanism of excimer laser ablation of inorganic materials. Because of the advantage of very short pulse duration of excimer lasers, the thermal effect is very small during excimer lasers processing. And most materials are strongly absorptive to excimer lasers. So precise processing can be achieved. By 193nm excimer laser cutting of Si wafer, we obtain better cutting edgers than that of YAG laser. LiNbO_3 is the most essential material for integrate-optics. Microstructuring on the surface of LiNbO_3 is very important to the development of integrate-optics. Nowadays, both erosion and RIE processing are not satisfied yet. By 193nm excimer laser ablation of LiNbO_3, good quality V-grooves are sucessful1y fabricated, which are used for installation or alignment of optical fiber. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16546]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 章琳. 准分子激光刻蚀聚合物制作微光学元件[D]. 中国科学院上海光学精密机械研究所. 2001. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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