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备，以提高生产率。首先，我们尝试制作模板面具。采用2 μm厚的Ti箔，通过FIB刻蚀，成功地制备出了300 × 300 nm^2的方孔模板掩模。良好的准直电子束是必要的，以防止扩大图案尺寸。掩模和样品之间的距离为10 μm是最佳的，以防止来自掩模的二次电子的不期望的曝光。最后，利用电子束投影光刻技术成功制备了尺寸为400 × 400 nm^2的自对准Pt电极PZT纳米电容器，并估算了铁电微电容器电滞特性测试中的寄生电容。扫描探针显微镜与导电悬臂用于接触到各种尺寸的PZT电容器。寄生电容的条件 ...更多信息 从电容器面积依赖性的滞后斜率估算出，将悬臂梁靠近衬底进行接触所增加的寄生电容为0.061pF。第二年，我们尝试制备铁电光子晶体。采用电子束诱导图形化技术成功制备了由PLZT基质和间距为800 nm、直径为560 nm的空气孔组成的铁电光子晶体。由于基质收缩，前体基质中内接于直径为400 nm的圆的异形孔在热处理后变为直径为560 nm的圆孔。还评价了CSD衍生的PLZT膜的光学性质。PLZT薄膜的折射率为2.3，克尔常数为0.4x10^<-16>m^2/V^2。因此，预期对1 μ m厚的PLZT光子晶体施加9.7V的电压引起折射率降低1%和波长为1.55 μm的光的40 μ o摆动。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