Fabrication of a 256-bits organic memory by soft x-ray lithography

This paper reports a procedure of soft x-ray lithography for the fabrication of organic crossbar structure. Electron beam lithography is employed to fabricate the mask for soft x-ray lithography, with direct writing technology to lithograph positive resist, polymethyl methacrylate on the polyimide film. Then Au is electroplated on the polyimide film. Hard contact mode exposure is used in x-ray lithography to transfer the graph from the mask to the wafer. The 256-bits organic memory is achieved with the critical dimension of 250~nm.     

Fabrication of broadband anti-reflective sub-micron structures using polystyrene sphere lithography on a Si substrate

Anti-reflective coatings are widely used on the surfaces of solar cells to increase the efficiency of photoelectric conversion. Sub-wavelength structures have gradually replaced conventional anti-reflective (AR) thin films due to their broadband AR properties. This paper successfully fabricated structures with a variety of surface morphologies on Si substrate using polystyrene sphere lithography in conjunction with two-step inductive coupling plasma (ICP) and high density plasma (HDP) etching processes. We successfully fabricated various sub-micron structures with heights of 700 nm and above. Experimental results show that the sub-micron pyramidal structure has the best anti-reflection performance with the average reflectance effectively suppressed to below 1% across the spectral range of 300–1200 nm.     

Outlook for projection x-ray lithography

The discovery of superconductivity with critical temperatures of ∼100 K opens new opportunities for wide-scale application of superconducting microelectronics devices with ultraminiature elements (less than 0.1 μm). Projection x-ray lithography could serve as a technological basis of such microelectronics. It is demonstrated that application of x-ray optics elements, production of which can be readily provided by modern technological facilities, makes it possible to produce microstructures with element dimensions of the order of tens of nanometers and to eliminate to a considerable extent the drawbacks inherent in contact lithography. Translated from Trudy Fizicheskogo Instituta im. P. N. Lebedeva (Proceedings of the Lebedev Physical Institute, Russian Academy of Sciences, Moscow), Vol. 196, pp. 130–142, 1989.     

Heterodyne polarimetry for mapping defects in lithography masks

A new optical technique based on the heterodyne polarimetry is developed for fast inspection of uniformity of lithography masks in semiconductor industry. Sub-wavelength periodical structure of a sample acts as a wire-grid polarizer, making both the amplitude and phase of the reflected laser beam dependent on geometrical dimensions and optical properties of the mask pattern. The heterodyne technology based on the cross-polarized two-frequency Zeeman laser is used to simultaneously measure the amplitude and the phase of the reflected laser beam. A two-dimensional map of spatial variations can be obtained via point-by-point scanning of the sample. The technique is applicable not only to exact periodical structures like diffraction gratings, but also to double-periodical patterns consisting of large number of periodically distributed small areas of sub-wavelength gratings. Theoretical background, simulation, and experimental results are presented.     

Fabrication of the uniform CdTe quantum dot array on GaAs substrate utilizing nanoporous alumina masks

Fabrication of quantum dot array (QDA) is attractive for applications in electronic and optoelectronic devices. The CdTe QDAs have potential applications in optoelectronic devices of visible range. One of the major challenges in fabricating QDAs is the uniformity and reproducibility in size and spatial distribution. The uniformity and reproducibility of QDs can be improved by using the nanoporous alumina mask. The geometry of porous alumina is schematically represented as a close-packed array of columnar hexagonal cells, each containing a central pore normal to the substrate. The well-ordered nanoporous alumina masks were able to obtain by two-step anodizing processes from aluminum in oxalic acid solutions at low temperature. The pore size, thickness, and density of nanoporous alumina mask can be controlled with the anodization voltage, time, and electrolyte. The CdTe QDAs on the GaAs substrate was grown by molecular beam epitaxy method using the porous alumina masks. The temperature of substrate and source (Cd, Te) was an important factor for the growth of CdTe QDs on GaAs substrate. The CdTe QDAs of 80 nm dot size was fabricated; using the porous alumina masks (300 nm thickness) of pore diameter (80 nm) and density (10¹⁰ /cm²).     

Features of the manufacture of deep X-ray lithography masks in the siberian synchrotron and terahertz radiation center

The development of a low-cost technology to manufacture high-contrast X-ray LIGA masks is topical because this technology is important for various applied research on microstructured products with minimum element sizes of 10–50 μm, such as microfluid analytical systems, selective waveguide mesh-based elements to control terahertz (THz) radiation, microshaped optical elements for the visible range, etc. Technological particularities of mask manufacture are considered. A method to check the quality of masks is presented. Test microproducts manufactured using the produced deep X-ray lithography masks are demonstrated.     

Fabrication of LIGA masks for microfluidic analytical systems

Preliminary results of fabrication and testing of LIGA mask samples for deep x-ray lithography in the spectral range of 3.5–13.5 keV are presented. The mask fabrication method is based on direct mask patterning with minimum element sizes of ≥ 10 μm by a synchrotron radiation x-ray microbeam. Such a method does not require an intermediate mask, which significantly simplifies fabrication and reduces the laboriousness and cost of LIGA masks.     

The use of x-ray capillary optics for lithography and microscopy

The possibilities of using x-ray capilary optics in lithography and microscopy are discussed. It has been shown experimentally that these systems, originally proposed by M. A. Kumakhov, may considerably simplify experimental designs. A micropinch x-ray source specially designed for these purposes has been successfully tested. The complete system constructed for laboratory use may serve as a prototype for an industrial lithography machine or microscope.     

Fabrication of a superhydrophobic surface on a wood substrate

A layer of lamellar superhydrophobic coating was fabricated on a wood surface through a wet chemical process. The superhydrophobic property of the wood surface was measured by contact angle (CA) measurements. The microstructure and chemical composition of the superhydrophobic coating were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). An analytical characterization revealed that the microscale roughness of the lamellar particles was uniformly distributed on the wood surface and that a zinc stearate monolayer (with the hydrophobic groups oriented outward) formed on the ZnO surface as the result of the reaction between stearic acid and ZnO. This process transformed the wood surface from hydrophilic to superhydrophobic: the water contact angle of the surface was 151°, and the sliding angle was less than 5°.     

厚胶接近式光刻中掩模优化研究（英）

随着光刻胶厚度的不断增大,制作的光刻图形畸变愈发严重,这极大的影响了微结构器件的性能与应用。针对高深宽比柱状微结构在光刻胶厚度方向上畸变的特点,提出了双面曝光和亮衬线、灰阶掩模相结合的办法,利用遗传算法对失真影响最大的区域进行搜索,光刻胶内部各层的衍射光场分布作为评价函数,对光刻过程引起的畸变进行优化。仿真结果显示,优化后光刻胶各层面型质量得到极大的改善,特征尺寸和边墙角等参数与理论值吻合得更好。优化算法具有很好的灵活性,因此在用于更厚光刻胶、更复杂掩模图形的优化上,具有重要的指导意义。     

厚胶接近式光刻中掩模优化研究（英）

随着光刻胶厚度的不断增大,制作的光刻图形畸变愈发严重,这极大的影响了微结构器件的性能与应用。针对高深宽比柱状微结构在光刻胶厚度方向上畸变的特点,提出了双面曝光和亮衬线、灰阶掩模相结合的办法,利用遗传算法对失真影响最大的区域进行搜索,光刻胶内部各层的衍射光场分布作为评价函数,对光刻过程引起的畸变进行优化。仿真结果显示,优化后光刻胶各层面型质量得到极大的改善,特征尺寸和边墙角等参数与理论值吻合得更好。优化算法具有很好的灵活性,因此在用于更厚光刻胶、更复杂掩模图形的优化上,具有重要的指导意义。     

Fabrication of quasi-optical selective elements for the terahertz range in the form of pseudometallic structures via deep X-ray lithography

A technique for fabricating self-bearing pseudometallic structures, which hold promise for utilization as quasi-optical frequency-selective elements in the terahertz range of the electromagnetic spectrum, is discussed. The technique is based on microstructuring a continuous dielectric layer via stencilled X-ray lithography involving synchrotron radiation with subsequent metallization of the entire structure surface. The main manufacturing schemes are described, including fabrication of the initial substrates and X-ray masks. Examples of samples of the produced selective elements, such as frequency filters and flat lenses, as well as their operating characteristics, are presented.     

花状纳米金结构阵列的工艺制备与拉曼增强研究

基于纳米球光刻技术制备了一种花状纳米金结构阵列,经过PS509 nm球旋凃和ICP氧刻蚀,再通过镀金膜与高温退火工艺,纳米球阵列的表面被粗糙化,进而形成了一种鳞状的花状阵列 。FDTD仿真结果表明,制备的这种阵列具备很高的电磁场增强特性,主要的增强集中于纳间隙的边缘处。以罗丹明 6G染料为探针分子测试基底的拉曼效应,与金基底的拉曼信号相比,该纳米结构阵列拉曼增强效应明显,对罗丹明 6G的检测极限达到了10-6 mol/L的水平。     

花状纳米金结构阵列的工艺制备与拉曼增强研究

基于纳米球光刻技术制备了一种花状纳米金结构阵列,经过PS509 nm球旋凃和ICP氧刻蚀,再通过镀金膜与高温退火工艺,纳米球阵列的表面被粗糙化,进而形成了一种鳞状的花状阵列 。FDTD仿真结果表明,制备的这种阵列具备很高的电磁场增强特性,主要的增强集中于纳间隙的边缘处。以罗丹明 6G染料为探针分子测试基底的拉曼效应,与金基底的拉曼信号相比,该纳米结构阵列拉曼增强效应明显,对罗丹明 6G的检测极限达到了10-6 mol/L的水平。     

Fabrication of high aspect ratio subwavelength gratings based on X-ray lithography and electron beam lithography

In this paper, we present two nano-fabrication technologies that provide effective approaches for low-cost, large-scale manufacturing of nano-gratings. One grating is fabricated on polymethylmethacrylate (PMMA) with the pitch of 500 nm, and height of 2000 nm, and the other is fabricated on silicon wafer with the pitch of 666 nm, and height of 200 nm. High aspect ratio PMMA nanostructures which use X-ray lithography and electron beam lithography (EBL) are reported in this paper. These gratings can be used as molds, making it possible for industrial nano-imprinting technology to significantly cut cost and shorten process time.     

双尺度织构的激光光刻工艺

搭建了双光束激光干涉光刻系统和激光快速扫描系统。利用干涉光刻系统,实现了不同周期、不同深度、大面积的表面规则光栅织构的构筑。利用激光快速扫描器的二维扫描功能,通过控制激光功率和扫描速度,对曝光量和填充线条间距进行了优化。提出了两种双尺度复合织构的制备方法：一种是在激光快速扫描系统中对抗蚀剂表面分别进行x, y方向的扫描光刻,然后在干涉光刻系统中进行双光束干涉光刻;另一种是在激光干涉光刻系统中进行两次曝光,每次曝光的入射角不同。实验结果表明：这两种方法在制备双尺度复合织构方面具有快速、廉价、操作简易等优点。     

投影电子束光刻中电子穿透掩膜的Monte Carlo模拟

利用基于Mott散射截面和介电函数模型的Monte Carlo方法模拟了电子穿透掩膜的能量损失分布，其计算结果与实验结果符合很好. 由此进一步计算了角度限制投影电子束光刻(SCALPEL)掩膜的穿透率和衬度，结果表明：散射体的厚度对衬度的影响较大，衬度随散射体厚度的增加而增强，而支撑体对衬度的影响较小；增大限制孔的孔径角时，透射率相应增大，但衬度会降低；衬度随入射电子的能量增加而减小. 关键词： Monte Carlo模拟 电子束光刻 掩膜     

Fabrication of submicron structures by three-dimensional laser lithography

As a demonstration of unique capabilities of three-dimensional laser lithography, an example complex-shape microobject and photonic crystals with “woodpile” structure for the infrared spectral range are fabricated by this technique. Photonic dispersion relations for the woodpile structure are calculated for different values of the permittivity contrast and the filling factor.