Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im...     

Formation mechanism of multi-functional black silicon based on optimized deep reactive ion etching technique with SF6/C4F8

This paper reports a controllable multi-functional black silicon surface with nanocone-forest structures fabricated by an optimized deep reactive ion etching(DRIE)technique using SF6/C4F8 in cyclic etching-passivation process,which is maskless,effective and controllable.The process conditions are investigated by systematically comparative experiments and core parameters have been figured out,including etching process parameters,pre-treatment,patterned silicon etching and inclined surface etching.Based on the experimental data,the formation mechanism of nanocone shape is developed,which provides a novel view for in-depth understanding of abnormal phenomena observed in the experiments under different process situations.After the optimization of the process parameters,the black silicon surfaces exhibit superhydrophobicity with tunable reflectance.Additionally,the quantitative relationship between nanocones aspect ratio and surface reflectance and static contact angle is obtained,which demonstrates that black silicon surfaces with unique functional properties(i.e.,cross-combination of reflectance and wettability)can be achieved by controlling the morphology of nanostructures.     

电化学脉冲腐蚀制备多孔硅微腔技术

基于电化学脉冲腐蚀方法,用正交实验法给出了制备多孔硅微腔较为理想的制备参数：脉冲周期为5ms,占空比为5／10和上下各6个周期Bragg镜面层,得到了半峰宽为6nm的窄峰发射的多孔硅微腔．并用了以HF酸扩散为基础的多孔硅动态腐蚀机理对实验结果进行了解释,认为在用电化学脉冲腐蚀法制备多孔硅微腔的过程中,不但要考虑到HF酸对硅的纵向腐蚀（电流腐蚀）,也要考虑到HF酸对多孔硅硅柱的横向腐蚀（浸泡腐蚀）．     

大气电弧等离子体技术在熔石英表面加工中的应用

为了快速获得无亚表面损伤光学表面,提出了一种新型的大气电弧射流等离子体加工方法,该方法的装置采用转移弧电弧放电原理产生大气射流等离子体,通过调节改变喷枪的气压及几何结构,对束斑的尺寸及能量密度进行调节,同时基于其束斑高能离子的物理效应,研究了大气条件下熔石英表面材料的加工工艺.实验结果表明:当采用等离子体喷枪嘴孔径2.5mm,作用距离为2.0mm时,对熔石英的峰值去除速率可达到82.9μm·min-1,单次抛光后,元件表面粗糙度Ra值由237nm下降到103nm.     

808nm高功率VCSEL刻蚀工艺研究

为提高808nm高功率VCSEL的光电性能,对不同实验条件下的氧化限制型VCSEL湿法刻蚀工艺进行了实验研究,制备出多环形电极结构VCSEL器件。实验中采用H3PO4系腐蚀液替代以往常用的H2SO4系腐蚀液,通过改变湿法刻蚀工艺的温度条件及腐蚀液的浓度配比,能够较精确的控制腐蚀深度,消除＂燕尾＂结构,最终确定808nm高功率VCSEL湿法腐蚀工艺的最佳温度条件及腐蚀液的最佳浓度配比。测试结果表明,采用这种湿法刻蚀工艺条件制备的808nm高功率VCSEL器件,室温下的阈值电流为430m A,微分量子效率为0.44W/A,最大输出功率达到0.42W,其光电性能远优于传统湿法刻蚀工艺制备的同种高功率VCSEL器件。     

利用硅的各向异性腐蚀技术批量制作压力传感器

介绍一种新颖的采用硅的各向异性化学腐蚀工艺形成压力传感器的技术.给出了各向异性腐蚀的机理,报告了三种不同腐蚀液(KOH,EPW,TMAH)的腐蚀工艺及实验结果.并结合腐蚀技术介绍了硅电容压力传感器的制作工艺.     

808nm激光诱导电化学刻蚀研究

为探讨半导体激光电化学刻蚀的工艺特性,采用808nm半导体激光作为光源,聚焦激光照射浸于溶液中的阳极上,实现激光诱导电化学刻蚀材料。在实验的基础上,通过对金属和半导体材料刻蚀的比较,分析了激光电化学刻蚀硅的工艺特点。实验表明,808nm激光诱导电化学刻蚀工艺是一个光热刻蚀过程,但不适合刻蚀半导体材料。     

Fabrication of inorganic film gratings and study on their diffraction properties

A novel process for fabricating high-density and high diffraction efficiency inorganic gratings has been proposed by combining laser interference and chemical etching. In the present work, UV photosensitive Zr-contained sol was synthesized, and photosensitive ZrO₂/BzAc gel films on (100) silicon were prepared using the sol-gel method. Subsequently, inorganic film gratings with a pitch of 1 μm were fabricated by laser interference in this photosensitive gel film combining with the process of heat treatment. In order to increase the depth-to-width ratio of the gratings, chemical etching was adopted by using iodine-saturated KOH as anisotropic etchant, which improved the diffraction efficiency of the gratings effectively. Furthermore, the diffraction efficiency was improved by gold coating to enhance the surface glossiness and reflection coefficient. Supported by the National Natural Science Foundation of China (Grant No. 90401009) and the Xi’an Applied Materials Innovation Fund (Grant No. XA-AM-200611)     

Straight SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> nanorod Y junctions

Novel straight silicon oxide [SiO _x (1<x<2)] nanorod Y junctions have been synthesized on Si plate by thermal evaporation of mixed powders of silica and carbon nanofibers at 1300°C and condensation on a Si substrate without assistance of any catalyst. The synthesized samples were characterized by means of scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The results suggested that the straight nanorod Y junctions are amorphous and consist only of elements Si and O, and these rods with diameters about 50–200 nm have a neat smooth surface. The growth of such silicon oxide nanorods may be a result of the second nucleation on the surface of rods causing a change in the growth direction of silicon oxide nanorods developed. Supported by the Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing, and the Program of Science & Technology Activity for Chinese Homecoming Fellow Abroad and Research Program of Beijing Key Laboratory for Sensor (Grant No. KM200810772009)     

低能离子束刻蚀单晶硅表面形貌与粗糙度的研究

研究了低能Ar＋离子束对单晶硅表面的刻蚀效果.使用自制的冷阴极离子源,通过控制离子束的入射能量和刻蚀时间等因素,对单晶硅（100）表面进行刻蚀,采用原子力显微镜（AFM）和非接触式表面测量仪对刻蚀后硅片的表面形貌以及表面粗糙度（RMS）进行测量.实验结果表明：当离子束正入射、束流密度为20μA/cm2、刻蚀时间为30min、刻蚀距离为7cm时,入射能量从800eV增加到1 200eV的过程中,此时表面光滑起主要作用,表面粗糙度逐渐减小;继续增大入射能量到1 600eV时,表面粗糙度开始增大,当入射能量达到1 400eV时,通过AFM观察,硅片表面出现了自组织纳米点状结构,此时表面粗糙起主要作用;延长刻蚀时间同样可以看到粗糙度先减小后增加,延长刻蚀时间到90min,表面的粗糙度达到1.245nm,AFM观察表明,随着时间的增加,由于样片表面原子扩散影响,点状结构排列趋于均匀.     

多晶硅的ECR等离子体刻蚀

报道了用CF4作工作气体的ECR刻蚀poly－Si技术，研究了微波功率、气体流量、气压和射频偏置功率对刻蚀速率的影响，并对实验结果进行了讨论，实验中微波等离子体功率范围在100－500W，CF4气体流量在10－50cm^3/min（标准状态下）范围，气压在0.25-2.5Pa范围，射频偏置功率在0－300W范围，对应的刻蚀速率为10.4-46.2nm/min。     

Fabrication of 3D structure by combining AFM and chemical etching on crystalline silicon surface

Anisotropic etching of monocrystalline silicon inalkaline solution has been researched for more than 40years, which is one of the key techniques in fabricationof different types of micromechanical structures such asdiaphragms and cantilevers on a silicon wafer[1]. Al-though having a lot of applications, it has many aca-demic and technical problems. Wet chemical etching,mostly performed using KOHsolution, is in general usefor microstructure[2 -4], which is based on the fact thatthe etching rat…     

Nonselective etching of GaN/AlGaN heterostructures by Cl<Subscript>2</Subscript>/Ar/BCl<Subscript>3</Subscript> inductively coupled plasmas

A systematic study of the nonselective and smooth etching of GaN/AlGaN heterostructures was performed using Cl₂/Ar/BCl₃ inductively coupled plasmas (ICP). Nonselective etching can be realized by adjusting the BCl₃ ratio in the Cl₂/Ar/BCl₃ mixture (20%–60%), increasing the ICP power and dc bias, and decreasing the chamber pressure. Surface morphology of the etched heterostructures strongly depends on the gas chemistry and the chamber pressure. Specifically, with the addition of 20% BCl₃ to Cl₂/Ar (4∶1) gas mixture, nonselective etching of GaN/Al_0.28Ga_0.72N heterostructures at high etch rate is maintained and the surface root-mean-square (rms) roughness is reduced from 10.622 to 0.495 nm, which is smoother than the as-grown sample. Auger electron spectroscopy (AES) analysis shows that the effective removal of residual oxygen from the surface of AlGaN during the etching process is crucial to the nonselective and smooth etching of GaN/AlGaN herterostructures at high etch rate.     

SiO2/ZnS核壳结构微球的制备和表征

以自制纳米二氧化硅微粒为模板,硫代乙酰胺和醋酸锌分别为硫源和锌源,通过沉淀法成功制备了SiO2/ZnS核壳结构微球,研究了各种反应条件对该微球形貌的影响。经NaOH溶液蚀刻后,SiO2/ZnS核壳结构微球转变成亚微米级的ZnS空心微球。通过XRD、SEM和TEM等手段对SiO2/ZnS核壳结构微球和ZnS空心微球进行了表征。结果表明,在优化条件下制得的微球形貌规整、大小均匀,其壳层由厚度约20 nm的ZnS纳米颗粒组成。     

Characterization of PZT/PVC Composites Added with Carbon Black

1Introduction Piezoelectricceramicshavebeenusedastheconven tionalintelligentmaterialsforalongtime.Theirinterest ingpropertiesusedintransducersarehighpiezoelectric straincoefficient(d33),highelectromechanicalcoupling coefficient(Kp)[15].However,therelative…     

Design and fabrication of erbium doped photosensitive fibers

A kind of erbium doped photosensitive fiber (EDPF) was proposed and fabricated, whose core was made of double layers named photosensitive layer and erbium doped layer. The double-layer core design can overcome difficulties in fabrication of EDPF with single core design, i.e. the conflict between the high consistency rare earth doping and high consistency germanium doping. A sample was fabricated through the modified chemical vapor deposition method combined with solution doping technique. The peak absorption coefficient was 48.80 dB/m at 1.53 μm, the background loss was lower than 0.1 dB/m, and the reflectivity of the fiber Brag gratings (FBG) written directly on the sample fiber was up to 97.3% by UV-writing technology. Moreover, a C band tunable fiber laser was fabricated using the sample fiber, in which a uniform FBG was written directly on EDPFs as a reflector. A single wavelength lasing with a maximum wavelength tuning range of 1555.2–1558.0 nm was achieved experimentally. Within this tuning range, the full-width at half maximum (FWHM) of the laser output was smaller than 0.015 nm and the side mode suppression ratio (SMSR) was better than 50 dB. Supported by the National High Technology Research and Development Program of China (863 Project) (Grant No. 2007AA01Z258), the National Natural Science Foundation of China (Grant No. 60771008), Program for New Century Excellent Talents in University (Grant No. NCET-06-0076), Beijing Natural Science Foundation (Grant No. 4052023), and the Beijing Jiaotong University Foundation (Grant No. 2006XM003)     

Fabrication of metal suspending nanostructures by nanoimprint lithography (NIL) and isotropic reactive ion etching (RIE)

We report herein a rational approach for fabricating metal suspending nanostructures by nanoimprint lithography (NIL) and isotropic reactive ion etching (RIE). The approach comprises three principal steps: (1) mold fabrication, (2) structure replication by NIL, and (3) suspending nanostructures creation by isotropic RIE. Using this approach, suspending nanostructures with Au, Au/Ti or Ti/Au bilayers, and Au/Ti/Au sandwiched structures are demonstrated. For Au nanostructures, straight suspending nanostructures can be obtained when the thickness of Au film is up to 50 nm for nano-bridge and 90 nm for nano-finger patterns. When the thickness of Au is below 50 nm for nano-bridge and 90 nm for nano-finger, the Au suspending nanostructures bend upward as a result of the mismatch of thermal expansion between the thin Au films and Si substrate. This leads to residual stresses in the thin Au films. For Au/Ti or Ti/Au bilayers nanostructures, the cantilevers bend toward Au film, since Au has a larger thermal expansion coefficient than that of Ti. While in the case of sandwich structures, straight suspending nanostructures are obtained, this may be due to the balance of residual stress between the thin films. Supported by the National Natural Science Foundation of China (Grant No. 20573002) and the Major State Basic Research Development Program of China (973Pprogram) (Grant No. 2001CB6105)     

GaAs backside via-hole etching using ICP system

A high etch rate GaAs via-hole process was studied in an inductively coupled plasma system using Cl2/BCl3 gas system. The effects of process parameters on the GaAs etch rate were investigated. The influences of photoresist SiO2 and Ni masks on the resultant profiles were also studied by scanning electron microscopy. A maximum etch rate of 8.9 μm/min was obtained and the etched profiles were optimized.     

改造国产ICP进行低温刻蚀

低温刻蚀被用来进行硅微深孔加工。文中介绍了感应耦合等离子体（ICP）刻蚀原理，通过对国产ICP进行改造，在SF6/O2气体条件下进行低温刻蚀，利用低温钝化机理控制工艺，减少器件损伤。     

基于0.5 μm BCD工艺的双向SCR结构的ESD保护设计

针对双向可控硅(DDSCR)在特征尺寸不断缩小的集成电路中,难以达到窄小静电放电(ESD)设计窗口的ESD防护需求,设计一种PMOS内嵌型浮栅DDSCR (GFDDSCR) ESD保护器件,并基于0.5 μm Bipolar-CMOS-DMOS工艺进行制备.利用传输线脉冲测试研究不同关键尺寸的GFDDSCR的ESD特性及单位面积ESD防护能力,分析器件ESD特性随关键尺寸变化的规律,得到优化的GFDDSCR的结构参数.结果表明,与DDSCR的改进型结构(IBDSCR)相比,优化的GFDDSCR触发电压下降了27%,电压回滞幅度减小了53%,维持电压和失效电流基本不变,能够满足微纳米级集成电路窄小ESD设计窗口的需求.