Fabrication of Ferroelectric Nanocapacitors by Electron-beam Projection Patterning

将电子束投影光刻技术应用于铁电纳米电容器的制造中，以提高产量。首先，我们尝试制作模板面具。采用厚度为2 μm的Ti箔，用FIB刻蚀法成功制备了300x300nm ^2的方孔模板。良好的电子束准直是防止图样尺寸展宽的必要条件。掩膜与样品之间的距离为10 μm，可有效防止二次电子对样品的不良暴露。最后，利用电子束投影光刻技术成功制备了具有自对准顶部Pt电极的400x400nm ^2尺寸的PZT纳米电容器。对测量铁电微电容器磁滞特性所涉及的寄生电容进行了估计。采用带导电悬臂的扫描探针显微镜对不同尺寸的压电陶瓷电容器进行了接触。从滞回斜率与电容面积的关系来看，当悬臂梁离接触点升高40 μm时，寄生电容的增加估计为0.88 pF。从滞回斜率与电容面积的关系来看，当悬臂梁靠近衬底时，寄生电容的增加估计为0.061 pF。利用电子束诱导图像化工艺成功制备了由PLZT基体和直径为560nm、间距为800nm的气穴组成的铁电光子晶体。前驱体基体中直径为400 nm的圆上的六角形孔在热处理后由于基体的收缩而变为直径为560 nm的圆孔。本文还对csd衍生的PLZT薄膜的光学性能进行了评价。PLZT薄膜的折射率为2.3，克尔常数为0.4 × 10^<-16> m^2/V^2。因此，在1 μm厚度的PLZT光子晶体上施加9.7 V电压，波长为1.55 μm的光的折射率降低1%，振荡40^o。少

A projection lithography technique of electron beam was applied to the fabrication of ferroelectric nanocapacitors to increase throughput. First of all, we tried to fabricate stencil masks. The stencil mask with square holes of 300x300 nm^2 was successfully prepared by using Ti foils with a thickness of 2 μm and etching them by FIB. Well-collimated electron beam was necessary to prevent the broadening pattern size. The distance of 10 μm between the mask and the sample was optimum for preventing undesirable exposure by secondary electrons from the mask. Finally, fine 400x400 nm^2-sized PZT nanocapacitors with self-aligned top Pt electrodes were successfully fabricated by the electron-beam-projection-lithography.Parasitic capacitances attended in the measurement of hysteresis properties of ferroelectric microcapacitors were estimated. A scanning probe microscope with a conductive cantilever was used for contacting to various sized PZT capacitors. A parasitic capacitance on condition the … More cantilever was lifted up by 40 μm from the contact point was estimated to be 0.88 pF. From the capacitor area dependence of the hysteresis slopes, the increase in parasitic capacitance by bringing the cantilever near to substrates for contact was estimated to be 0.061 pF.In the second year, we tried to fabricated ferroelectric photonic crystals. Ferroelectric photonic crystals consisted of a PLZT matrix and 800 nm-pitch air-holes with a diameter of 560 nm were successfully fabricated by the electron-beam-induced patterning process. Hexagonal holes inscribed to the circles with a diameter of 400 nm in a precursor matrix changed to circular holes with a diameter of 560 nm after heat-treatment due to shrinkage of the matrix. The optical properties of CSD-derived PLZT films were also evaluated. The PLZT films showed the refractive index of 2.3 and the Kerr constant of 0.4x10^<-16> m^2/V^2. Therefore, it is expected that an applied voltage of 9.7 V to 1 μm-thick PLZT photonic crystals induces 1%-decrease in refractive index and 40^o-swinging of light with a wavelength of 1.55 μm. Less