微结构衬底上聚合物薄膜的自组织行为及其应用

发布时间：2018-08-24 13:29

【摘要】：薄膜在技术工艺和科学研究中有非常广泛的应用,研究聚合物薄膜在不同条件下自组织的行为,可以更有针对性地保持薄膜的稳定性,同时有助于控制薄膜的自组织行为形成独特的微结构。三维金属微腔阵列结构可以独立调控局域和非局域表面等离激元及其相互作用,产生许多独特的功能和物理性质,而传统微加工技术在制备大面积金属周期微纳结构的无法兼顾可控性和效率,寻找一种经济高效的金属微腔的制备方法逐渐成为研究的热点。本文在研究了 PS/PMMA共混薄膜以及PS薄膜在物理修饰硅衬底上退火时受限自组织生长的机制,以重复可控地制备大面积规则有序的聚合物微滴阵列的基础上,结合微纳加工的图案转移技术制备三维蘑菇状金属微腔阵列结构,并进一步研究了其物性。本论文的研究成果主要包含以下几个方面:第一,研究了物理修饰的周期孔洞对硅衬底上PS/PMMA共混薄膜退火自组织行为的影响。重量比为1:1的PS/PMMA共混薄膜在平衬底上通过失稳分解的方式自组织相分离,而对于周期孔洞的硅衬底上的PS/PMMA共混薄膜,孔洞改变系统的局部表面能,提供了人工的成核点,使得在薄膜退火时存在成核过程,但其影响范围有限。当衬底上孔洞周期较大时,薄膜主要通过失稳分解过程破裂,而聚合物微滴在彼此合并的过程中,受到近邻孔洞排斥的作用力。当孔洞周期较小时,成核为薄膜主要的破裂过程,成核形成的空洞很快彼此接触,更易形成有序的微结构阵列。第二,研究周期孔洞硅衬底上PS单层膜的退火自组织成核Dwetting过程,与共混膜系统比较,进一步确认孔洞在系统中的作用。硅衬底上PS单层膜主要通过成核的方式破裂,其退火后微结构的分布受初始成核点分布的影响,周期孔洞作为人为引入的成核点能够有效地控制PS薄膜的Dwetting过程。与共混膜在退火自组织过程中的双层结构相比,PS单层膜与硅衬底表面氧化层不浸润,其Dewetting成核过程中形成的空洞范围很大,而只要衬底上孔洞的周期小于自发成核点之间的平均间距就可以形成规则的PS微滴,更适合于制备大面积的微结构阵列,退火过程中PS微滴的受力及其与衬底上的孔洞的相互作用有待进一步研究。第三,以PS薄膜与PS/PMMA共混薄膜在周期孔洞硅衬底上退火自组织形成的微滴阵列为模板,通过后续图形转移制备三维金属微腔阵列。讨论了两种方式的优劣,提供了一种经济有效制备大面积金属微结构阵列的方法。金属微腔中金属圆盘尽管阻挡了电磁波的直接透射,但相对于金属孔其透射强度却有明显的增强。第四,利用电子束曝光技术制备不同参数的三维金属微腔阵列,研究结构参数对的光学性质的影响。三维蘑菇状金属微腔的高度和直径影响圆孔和金属圆盘之间锥形的硅柱结构参数,进而改变介质的有效介电常数,可以独立调节局域共振模式,其与非局域表面等离激元的相互作用可以增强透射谱的强度,而当两者的频率接近时其耦合作用可以使透射谱的峰位出现明显的红移,而频率高于局域共振频率的电磁波透射受到抑制。
[Abstract]:Thin films are widely used in technology, technology and scientific research. Studying the self-organized behavior of polymer films under different conditions can keep the stability of the films more pertinently, and help to control the self-organized behavior of the films to form unique microstructures. Nonlocal surface plasmons and their interactions produce many unique functions and physical properties. However, traditional micro-fabrication techniques can not give consideration to both controllability and efficiency in fabricating large area metal periodic microstructures. It is becoming a hot topic to find an economical and efficient method for fabricating metal microcavities. The mechanism of confined self-organizing growth of blend films and PS films annealed on physically modified silicon substrates was investigated. Based on the repetitive and controllable preparation of large-area ordered polymer microdroplet arrays, the three-dimensional mushroom-like metal microcavity arrays were fabricated by pattern transfer technique combined with micro-nano processing. The main achievements of this paper are as follows: Firstly, the effect of periodic pores on the annealing self-organization behavior of PS/PMMA blend films on silicon substrate is studied. The PS/PMMA blend films with a weight ratio of 1:1 are self-organized phase separation by instability decomposition on flat substrate, while the PS/PM blend films with periodic pores on silicon substrate are self-organized phase separation by instability decomposition. In MA blend films, voids change the local surface energy of the system and provide an artificial nucleation point, which leads to the existence of nucleation process during annealing, but its influence range is limited. The nucleation is the main breakdown process of the film when the void cycle is small. The voids formed by nucleation contact each other quickly and form ordered microstructure arrays more easily. Second, the annealing self-organized nucleation process of PS monolayer on periodic void silicon substrate is studied. Compared with the blend film system, the voids in the system are further confirmed. PS monolayer on silicon substrate is broken mainly by nucleation. The distribution of microstructure after annealing is affected by the distribution of initial nucleation points. Periodic voids as artificial nucleation points can effectively control the Dwetting process of PS films. Compared with the double-layer structure of the blend films during annealing self-organization, PS monolayer and silicon lining are more effective. As long as the period of voids on the substrate is less than the average spacing between the spontaneous nucleation points, regular PS droplets can be formed, which is more suitable for fabricating large-area microstructural arrays. Thirdly, three-dimensional metal microcavity arrays are fabricated by subsequent pattern transfer using self-organized droplet arrays formed by annealing of PS films and PS/PMMA blends on periodically porous silicon substrates as templates. The advantages and disadvantages of the two methods are discussed, providing an economical and effective way to fabricate large-area metal microcavity arrays. METHODS. Although metal discs in metal microcavities obstruct the direct transmission of electromagnetic waves, their transmission strengths are obviously enhanced compared with metal holes. Fourthly, three-dimensional metal microcavity arrays with different parameters are fabricated by electron beam lithography to study the effects of structural parameters on optical properties. Diameter affects the structural parameters of the conical silicon column between the circular hole and the metal disk, and then changes the effective dielectric constant of the medium, which can independently adjust the local resonance mode. Its interaction with the non-local surface plasmon can enhance the intensity of the transmission spectrum. When the frequency of the two is close to each other, the coupling effect can make the peak of the transmission spectrum out. The red shift is obvious, and the transmission of electromagnetic wave with higher frequency than the local resonance frequency is suppressed.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：O484

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