硅微通道板电子倍增器的研制

阐述了新一代硅微通道板的主要性能。采用定向离子深度刻蚀技术在2和4硅片上刻蚀了四组不同直径的硅微通道板微孔阵列,分别采用PECVD技术和液体化学沉积两种方法制作了硅微通道板的连续打拿极,从而探索了研制新一代硅微通道板的途径。利用紫外光电法测试了硅微通道板的增益和增益均匀性。实验结果表明,如果进一步改进制备工艺,硅微通道板可以实现较传统微通道板更高的增益和更好的增益均匀性。     

微透镜制作中光刻胶与衬底匹配行为的研究

利用光刻/离子束刻蚀制作大面阵硅微透镜阵列,采用SEM和表面探针测试等手段分析所制样品的形貌特点,定性讨论制备工艺的不同对所制器件的影响.所用工艺为大面阵微尖阵列和微合阵列的离子束刻蚀制作奠定了基础.     

两种玻璃微通道阵列的制作技术及比较

微孔玻璃阵列是采用原子层沉积技术制作微通道板的基底板,其微孔阵列的分布均匀性以及每个通道内壁的光滑程度,对其后续制作合格微通道板至关重要。分别采用空芯工艺和实芯腐蚀工艺来制作上述基底板,分析了两种技术的优缺点,阐述了两种方法中的关键技术,并对原子沉积技术制作的微通道板与常规工艺制作的微通道板进行了性能比较,前者的信噪比优于后者。     

凹折射微透镜阵列的离子束刻蚀制作

利用光刻热熔成形工艺及离子束刻蚀制作 12 8× 12 8元凹微透镜阵列。所制硅及石英凹微透镜的典型基本图形分别为凹球冠形、凹柱形和矩顶凹面形。分析了在光致抗蚀剂柱凹微透镜图形制作过程中的膜系匹配特性 ,与制作该种微透镜有关的光掩模版的主要结构参数 ,以及光致抗蚀剂掩模工艺参数的控制依据等。探讨了在凹微透镜器件制作基础上利用成膜工艺开展平面折射微透镜器件制作的问题。采用扫描电子显微镜 (SEM)和表面轮廓仪测试了所制石英凹微透镜阵列的表面微结构形貌。给出了所制石英凹微透镜阵列远场光学特性的测试结果。     

飞秒激光和酸刻蚀方法制作凹面微透镜阵列

基于飞秒激光光刻技术和氢氟酸对光学玻璃的刻蚀,在K9光学玻璃表面制作了凹面微透镜阵列,并且可以以此为模板实现凸微透镜阵列的大量复制.用相位对比显微镜和扫描电子显微镜分析了微透镜阵列的表面轮廓,测试了微透镜阵列的光学衍射特征.该方法简单、透镜参量可控,制作的微透镜阵列能够用于分光、光束匀化、并行光刻等强激光领域.     

多孔硅阵列结构的形貌研究

采用电化学腐蚀方法分别在HF+异丙醇（IPA）和HF+IPA+十六烷基三甲基氯化铵（CATC）溶液中制备多孔硅结构阵列,分别讨论HF酸浓度、CTAC、刻蚀电流、刻蚀时间对多孔硅阵列的形貌的影响。结果表明:在质量分数40%HF, H2O, IPA的体积比为7∶4∶29时得到优化的多孔硅阵列;腐蚀电流密度越大,孔壁越薄;初始的腐蚀会向外扩展直到形成的孔径达近10 m,在窗口8 m、间距5 m的硅片上腐蚀的孔壁表面出现小孔。CTAC的加入会使孔壁上刻蚀出小孔,并随着CTAC的增加,小孔的孔径减小,数量增加。     

激光刻蚀对镀金表面二次电子发射的有效抑制

使用红外激光刻蚀技术在镀金铝合金表面制备了多种形貌的微孔及交错沟槽阵列.表征了两类激光刻蚀微阵列结构的三维形貌和二维精细形貌,分析了样品表面非理想二级粗糙结构的形成机制.研究了微阵列结构二次电子发射特性对表面形貌的依赖规律.实验结果表明:激光刻蚀得到的微阵列结构能够有效抑制镀金表面二次电子产额(secondary electron yield,SEY),且抑制能力明显优于诸多其他表面处理技术;微阵列结构对SEY的抑制能力与其孔隙率及深宽比呈现正相关,且孔隙率对SEY的影响更为显著.使用蒙特卡罗模拟方法并结合二次电子发射唯象模型和电子轨迹追踪算法,仿真了各微结构表面二次电子发射特性,模拟结果从理论上验证了微阵列结构孔隙率及深宽比对表面SEY的影响规律.本文获得了能够剧烈降低镀金表面SEY的微阵列结构,理论分析了SEY对微结构特征参数的依赖规律,对开发空间微波系统中低SEY表面及提高镀金微波器件性能有重要意义.     

飞秒激光和酸刻蚀方法制作凹面微透镜阵列

基于飞秒激光光刻技术和氢氟酸对光学玻璃的刻蚀,在K9光学玻璃表面制作了凹面微透镜阵列,并且可以以此为模板实现凸微透镜阵列的大量复制.用相位对比显微镜和扫描电子显微镜分析了微透镜阵列的表面轮廓,测试了微透镜阵列的光学衍射特征.该方法简单、透镜参量可控,制作的微透镜阵列能够用于分光、光束匀化、并行光刻等强激光领域.     

飞秒激光湿法刻蚀微纳制造

飞秒激光微加工作为一种新型微纳制造技术,在复杂三维构型制作方面具有其独特的优势,但激光加工效率问题严重制约了飞秒激光微加工技术走向实际工程应用,提出一种飞秒激光湿法刻蚀微纳制造方法,以提高飞秒激光微加工的效率为突破口,通过调控激光与物质相互作用获得材料的目标靶向改性,进而结合化学湿法刻蚀实现硬质材料上的高效和高精度三维微加工,采用这一方法制作出的微透镜尺寸为80 m,球冠高6.7 m,表面粗糙度小于10 nm。利用这种方法,实现了不同结构与特性的高质量微透镜阵列的超精密制备,在石英内部也实现了螺旋微通道的复杂三维结构,螺旋通道直径为20 m,长径比超过100。     

红外微透镜阵列及其与MCT红外焦平面的集成

针对中短波碲镉汞（MCT）红外焦平面探测器的使用要求,设计了用于混合集成和单片集成且尺寸大小与探测器像元结构匹配的方形底折射微透镜阵列。采用热熔成形和（反应）离子柬刻蚀转移技术制作了多种红外材料微透镜,如Si、Ge、GaAs、蓝宝石以及红外玻璃（IRG-103和IRG-104）微透镜。针对混合集成和单片集成的不同要求,选用多种光刻胶如AZ6112和AZ6130等不同厚度的胶以及SUN-120P低熔点正型光刻胶,进行热熔和刻蚀实验,遴选分别适用于混合和单片集成的光刻胶。优化光刻胶和衬底材料的刻蚀速率比,得到高填充因子和合适光学参数的微透镜阵列。探究了SUN-120P低熔点正型光刻胶的特性和通过离子柬刻蚀转移视线实现零间距透镜的工艺。最后介绍了与MCT红外焦平面阵列器件的集成方式和工艺进展。     

Improved performance of solar cell based on porous silicon surfaces

Porous silicon (PS) surfaces were fabricated by electrochemical etching for both sides of the Si wafer. The objective of the present study is to investigate the PS effect on performance of silicon solar cells. Moreover, enhancement of solar cell efficiency can be obtained by manipulating of the reflected mirrors, and the process is very promising for solar cells manufacturing due to its simplicity, lower cost and suitability for mass production. The surface of PS is observed to have been discrete pores with smooth walls, and with short branches pores for the polished wafer side. In contrast, the etched backside of the wafer was observed to have bigger pore size than the etched polished side, and pores on the surface are in random location. PS formed on the both sides has lower reflectivity value in comparison to the other researcher group. The increase in efficiency of solar cell fabricated with PS formed on both sides of the wafer were extremely observed in comparison to one side PS and bulk silicon solar cells respectively. Solar cell fabricated shows that the conversion efficiency increased to 14.5% in comparison to unetched sample. The porous surface texturing properties could enhance and increased the conversion efficiency of silicon solar cells, these results also showed that the efficiency with this procedure is more promising in comparison to other solar cells, which are fabricated under similar conditions.     

A novel method of fabricating porous silicon material: ultrasonically enhanced anodic electrochemical etching

Ultrasonically enhanced anodic electrochemical etching is developed to fabricate luminescent porous silicon (PS) material. The samples prepared by the new etching method exhibit superior characteristics to those prepared by conventional direct current etching. By applying ultrasonically enhanced etching, PS microcavities with much higher quality factors can be fabricated. The improved quality induced by ultrasonic etching can be ascribed to increased rates of escape of hydrogen bubbles and other etched chemical species from the porous silicon pillars' surface. This process will cause the reaction between the etchant and the silicon wafer to proceed more rapidly along the vertical direction in the silicon pores than laterally.     

硬X射线相位光栅的设计与研制

针对在普通实验室和医院实现40—100keVX射线相衬成像的需求,考虑到成像系统参数、X射线源空间相干特性及光栅衍射效率,设计出硅基相位光栅结构参数.利用我们已发展的光助电化学刻蚀技术研制出直径为5英寸的相位光栅,其空间周期为5.6μm,线宽为2.8μm,深度为40—70μm.在理论分析的基础上,通过提高硅片两端有效工作电压和修正Lehmann电流密度公式,解决了实际刻蚀过程中出现的钻蚀问题.由实验结果可知,本方案对制作大面积高精度相位光栅十分有效。     

Self-assembled mesoporous silicon in the crossover between irregular and regular arrangement applicable for Ni filling

Porous silicon (PS) channels fabricated during an electrochemical anodization process in hydrofluoric acid solution, without pre-structuring, normally arrange in an irregular morphology. In this work self-organized quasi-2D regular pore arrangements have been fabricated by accurate mutual control of various process parameters. Self-organized pore formation can be tailored and periodic pore arrangements are possible. A particular parameter to vary the inter-pore spacing is mainly the HF concentration, whereas the pore diameter primarily depends on the current density. The well-separated pores are highly oriented perpendicular to the surface and the pattern of self-organized pores is quadratic like due to the (1 0 0)-crystal orientation of the wafer. The isolated pores show little dendritic growth and their diameter can be tuned between 10 and 100 nm, thus belonging to the meso-porous up to the macro-porous regime. The pore growth occurs in an anisotropic manner which means that the channels grow significantly faster in (1 0 0) direction than in (1 1 1) direction. Into this self-assembled PS template metallic Ni is deposited using an electrochemical deposition step which results in a PS/Ni-nanocomposite with potential for applications as magnetic and magneto-optical devices. The filling process is performed under cathodic conditions and could be refined by pulsed current charging.     

Porous silicon layers prepared by electrochemical etching for application in silicon thin film solar cells

In this paper, multilayer structures of porous silicon were fabricated by using electrochemical etching and characterized for its optical properties and surface morphology. Samples of monolayer of porous silicon were grown to study the characteristics of porous layer formation with respect to applied current density, etching time and hydrofluoric acid concentrations. Photoluminescence peaks of red emission at wavelength 695 and 650 nm were observed from multilayer porous silicon structures. By atomic force microscopy measurement, hillocks like surface were clearly observed within the host material, which confirmed the formation of pores.     

Nanoporous silicon fabricated at different illumination and electrochemical conditions

The properties of porous silicon prepared at different illumination and electrochemical conditions were studied. The preparation procedure was based on the electrochemical etching in HF containing electrolyte. In the dissolution of n-type silicon, an external source of light is necessary to obtain a sufficient holes flux density. Here, illumination was applied from the backside of the wafer (the side not immersed in the electrolyte), from topside (the side immersed in the electrolyte), and for the highly doped silicon, etching proceeds without illumination. The electrolyte contains HF in the range 2–50 wt%. The highest current density flows with topside assisted illumination. Backside illumination and etching in the dark resulted in a reduction in the current density. In the dark the current density significantly increased at a higher anodic bias. These conditions gave rise to pores formation with a diameter from 20 nm up to 3 μm. The smallest pore size was obtained for highly doped n-Si (111) wafers, etched without illumination. The present paper confirms the possibility of porous silicon formation in the dark and with backside illumination, these being alternative methods for topside assisted illumination etching methods.     

Development of three-dimensional microstructure processing using macroporousn-type silicon

The development of a micromachining technique for processing arbitrary structures with high aspect ratios in bulk silicon is presented. It is based on utilizing standard microelectronic processes and electrochemical macropore formation onn-type silicon in electrolytes containing hydrofluoric acid. This pore-etching technique allows us to produce very regular pore arrays with pore diameters and distances in the micrometer range and pore lengths up to wafer thickness. Samples with prefabricated pore arrays which differ in pore spacing, pore diameter and geometry are used as substrates for a micromachining process. The pores will facilitate the anisotropic etch profile which is required for the desired high aspect ratios although an isotropic etch process is used. Very deep microstructures with steep pore walls and aspect ratios of 10–15 are produced with this technique. It is shown that smaller pore array dimensions improve microstructure resolution.     

Fabrication of silicon wafer with ultra low reflectance by chemical etching method

A pyramid and nanowire binary structure of monocrystalline silicon wafer was fabricated by chemical etching. Much lower reflectance of silicon wafer with this structure was obtained compared with that of single pyramid or nanowaire arrays. The morphology, reflectivity and etching thickness of this structure were studied, as well as the influence on them caused by etching time and thickness of silver film. An average reflectance of 0.9% was obtained under optimized condition. The formation mechanism of silicon nanowires was explained by experimental evidence.     

Development of x-ray scintillator functioning also as an analyser grating used in grating-based x-ray differential phase contrast imaging

In order to push the grating-based phase contrast imaging system to be used in hospital and laboratories,this paper designs and develops a novel structure of x-ray scintillator functioning also as an analyser grating,which has been proposed for grating-based x-ray differential phase contrast imaging. According to this design,the scintillator should have a periodical structure in one dimension with the pitch equaling the period of self-image of the phase grating at the Talbot distance,where one half of the pitch is pixellated and is made of x-ray sensitive fluorescent material,such as CsI(Tl),and the remaining part of the pitch is made of x-ray insensitive material,such as silicon. To realize the design,a deep pore array with a high aspect ratio and specially designed grating pattern are successfully manufactured on 5 inch silicon wafer by the photo-assisted electrochemical etching method. The related other problems,such as oxidation-caused geometrical distortion,the filling of CsI(Tl) into deep pores and the removal of inside bubbles,have been overcome. Its pixel size,depth and grating pitch are 3 μm×7.5 μm,150 μm and 3 μm,respectively. The microstructure of the scintillator has been examined microscopically and macroscopically by scanning electron microscope and x-ray resolution chart testing,respectively. The preliminary measurements have shown that the proposed scintillator,also functioning as an analyser grating,has been successfully designed and developed.