采用防Footing效应工艺加工的SOI微加速度计

为了解决深刻蚀绝缘体上硅(silicon on insulator,SOI)材料时存在的横向刻蚀(Footing)效应,在背腔释放SOI微机电系统(micro electro mechanical system,MEMS)工艺基础上,提出并实现了一种改进的利用背面保护电极抑制Footing效应的工艺方案.在SOI圆片上生长SiO2和Si3N4掩模材料并图形化后,背面腐蚀支撑层Si至掩埋层SiO2.去除掩埋层SiO2后,完成正面Al电极和背面保护Al电极的溅射.深反应离子干法刻蚀SOI圆片形成结构,再腐蚀背面Al薄膜完成结构释放.基于该工艺,对结构层厚度为80μm的采用双端固支梁的SOI微加速度计的结构进行设计与仿真、器件加工和最终的性能测试.加速度计在±1 g(g=9.8 m/s2)范围内的灵敏度和非线性度分别为106.7 mV/g和0.1%.实验结果表明,该改进工艺方案可以有效抑制Footing效应对器件结构的损伤,提高加工的可靠性.     

MEMS中多孔硅绝热技术

主要介绍了多孔硅的制备方法(化学法、电化学法及原电池法等)、多孔硅导热系数测试的几种常用手段(温度传感器法、显微拉曼散射法及光声法等)、导热系数的理论模型及影响因素．此外,采用不同方法制备了多孔硅样品,分析了其表面形貌并用显微拉曼光谱法测定了导热系数．结果发现,化学法制备的多孔硅孔径尺寸大于微米量级,而利用大孔硅电化学和原电池法得到的样品孔径尺寸小(约20nm),属于介孔硅．由于腐蚀条件的不同,多孔硅的孔隙率和厚度也不同,多孔硅的导热系数随孔隙率和厚度的增大而迅速减小．     

真空技术在航空机电部件制造中的应用

真空技术在航空工业发展中得到越来越广泛的应用,以满足新型飞机高速发展对航空机电部件制造提出的越来越苛刻的技术要求.本文初步探讨了真空技术在:纳米加工、微电子电路、平板显示器件、光电传感器和微机电系统制造等航空机电产品关键制造技术开发中的应用.     

烟气活性焦干法脱硫工艺及其在电厂中的应用

用活性焦干法进行脱硫是一种新型的净化处理方式,其特点就是节约水资源,净化效率高,且原材料可以循环利用等等,尤其特别适用于发电厂的烟气脱硫化处理。文章首先对活性焦干法工艺原理进行了阐述,随后对其工艺流程作了介绍,最后对其在电场中的应用进行了举例分析。     

部分耗尽环栅CMOS/SOI总剂量辐射效应研究

采用硅离子注入工艺对注氧隔离(SIMOX)材料进行改性,在改性材料和标准SIMOX材料上制作了部分耗尽环型栅CMOS/SOI反相器,并对其进行60Co γ射线总剂量辐照试验.结果表明,受到同样总剂量辐射后,改性材料制作的反相器与标准SIMOX材料制作的反相器相比,转换电压漂移小的多,亚阈漏电也得到明显改善,具有较高的抗总剂量辐射水平.     

干法工艺的粉体技术在磨料行业的应用

根据气流粉碎磨料的现实情况 ,提出采用与气流分级系统相配套的加工工艺 ,生产出符合标准的磨料产品。只要解决稳定的分级粒度和制备的耐磨技术问题 ,干法工艺的粉体技术在磨料行业应用就能成为现实     

SOI NMOS晶体管在高剂量的X射线与60Coγ射线辐射作用下的背栅阈值电压漂移饱和效应的研究及比对

利用标准SIMOX材料制作了部分耗尽环型栅NMOS晶体管,并在ON偏置条件下分别对其进行了10keVX射线及^60Coγ射线总剂量辐照实验。实验结果表明,在两种辐射条件下NMOS晶体管的背栅阈值电压漂移量都会随着辐照剂量的升高而趋于饱和。实验分析并研究了这种现象的机理,并发现在较低的辐照剂量下^60Coγ射线造成的背栅阈值电压漂移量较大,但在高剂量条件下X射线造成的漂移量将超过^60Coγ射线。     

具有“荷叶效应”的硅基仿生表面的制备及其微摩擦性能

用扫描电子显微镜(scanning electron microscope,SEM)观测了荷叶表面的双微观结构,即特征尺度在10μm左右的微米乳突和直径为50～100 nm的纳米蜡质晶体.提出了制备具有"荷叶效应"的硅基仿生表面的两种方法,一是将表面制有特征尺度为100 nm左右纳米结构的硅片进行硅烷化疏水处理,仅制作了纳米结构,部分模拟了"荷叶效应;"另一种方法是将表面制有特征尺度为10μm左右微米结构的硅片进行烷基烯酮二聚体(AKD)化处理,该方法获得了具有双微观结构的仿生表面,比较完整地模拟了"荷叶效应."微摩擦性能测试结果表明光滑硅片微观摩擦系数为0.08～0.10,而具有120 nm～25μm微结构的硅片微观摩擦系数为0.04～0.07;具有特征尺度为200 nm线条阵列的粗糙区平均黏附力与光滑区平均黏附力之比为0.59.硅基仿生表面有利于降低摩擦系数和减小黏附,"荷叶效应"对于微机电系统(micro electro mechanical system,MEMS)防黏减摩具有一定的潜在应用价值.     

基于单晶硅的压阻效应的超小型压力传感器

利用单晶硅的压阻效应原理,采用先进的半导体平面工艺、微机械加工工艺、温度补偿及固态集成工艺研制了一种超小型压力传感器.该传感器采用敏感元件与信号处理电路一体化结构,产品在制作过程中经过严格的工艺检验和环境性能试验.证明具有体积小、精度高、稳定性好、测量范围宽等特点,可以广泛用于石油、冶金、化工、航空、航天、武器装备等领域压力的测量和控制.     

功能材料在MEMS中的应用及进展

以硅材料为基础的微机电系统MEMS被人们认为是21世纪革命性的新技术,是实现信息采集、处理、执行一体化,使之成为真正的系统.本文论述了MEMS的加工技术对材料提出的要求,以及近年来各种硅材料和功能材料在MEMS的应用和最新进展.     

纳米技术时代的高端硅基材料-SOI,sSOI和GOI

本文综述了纳米时代的高端硅基材料-SOI,sSOI和GOI,并结合介绍了上海微系统所和上海新傲科技有限公司相关的研究工作.     

虚拟MEMS加工工艺建模、实现与系统验证

利用虚拟现实技术对MEMS加工工艺进行仿真,并将其引入设计环节,最终可以解决MEMS生产中设计与加工脱节的问题。MEMS加工工艺的核心是工艺模型。首先,在深入分析单步MEMS加工工艺的基础上给出了规则描述的工艺模型,其次,利用专家系统技术实现了系统。进一步用一种全新的器件微流量泵的工艺设计和虚拟加工过程验证了系统的可扩充性。     

A Vibrating Plate Fabricated by the Methods of Microelectromechanical Systems (MEMS) for the Simultaneous Measurement of Density and Viscosity: Results for Argon at Temperatures Between 323 and 423K at Pressures up to 68 MPa

In the petroleum industry, measurements of the density and viscosity of petroleum reservoir fluids are required to determine the value of the produced fluid and the production strategy. Measurements of the density and viscosity of petroleum fluids require a transducer that can operate at reservoir conditions, and results with an uncertainty of about ±1% in density and ±10% in viscosity are needed to guide value and exploitation calculations with sufficient rigor. Necessarily, these specifications place robustness as a superior priority to accuracy for the design. A vibrating plate, with dimensions of the order of 1 mm and a mass of about 0.12 mg, clamped along one edge, has been fabricated, with the methods of Microelectromechanical (MEMS) technology, to provide measurements of both density and viscosity of fluids in which it is immersed. The resonance frequency (at pressure p = 0 is about 12 kHz) and quality factor (at p = 0 is about 2800) of the first order bending (flexural) mode of the plate are combined with semi-empirical working equations, coefficients obtained by calibration, and the mechanical properties of the plate to provide the density and viscosity of the fluid into which it is immersed. When the device was surrounded by argon at temperatures between 348 and 423 K and at pressures between 20 and 68 MPa, the density and viscosity were determined with an expanded (k = 2) uncertainty, including the calibration, of about ±0.35% and ±3%, respectively. These results, when compared with accepted correlations for argon reported in the literature, were found to lie within ±0.8% for density and less than ±5% for viscosity of literature values, which are within a reasonable multiple of the relative combined expanded (k = 2) uncertainty.     

虚拟MEMS加工工艺的定义、关键技术与实现框架

首先提出了虚拟MEMS加工工艺的概念,它是利用图形动态生长,来模拟每步工艺过程,整个工艺过程中形状变化均包含在虚拟工艺中。其次,分析了实现虚拟工艺所涉及的关键技术：工艺描述、工艺模型和加工过程的可视化。第三,给出了基于专家系统技术的虚拟工艺实现框架。最后,实现了一种表面硅工艺的例子,初步验证了实现框架时间和精确度的可行性。     

Silicon Nanowires Driving Miniaturization of Microelectromechanical Systems Physical Sensors: A Review

The miniaturization of microelectromechanical systems (MEMS) physical sensors is driven by global connectivity needs and is closely linked to emerging digital technologies and the Internet of Things. Strong technical advantages of miniaturization such as improved sensitivity, functionality, and power consumption are accompanied by significant economic benefits due to semiconductor manufacturing. Hence, the trend to produce smaller sensors and their driving force resemble very much those of the miniaturization of integrated circuits (ICs) as described by Moore's law. In this respect, with its IC-, and MEMS-compatibility, and scalability, the silicon nanowire is frequently employed in frontier research as the sensor building block replacing conventional sensors. The integration of the silicon nanowire with MEMS has thus generated a multiscale hybrid architecture, where the silicon nanowire serves as the piezoresistive transducer and MEMS provide an interface with external forces, such as inertial or magnetic. This approach has been reported for almost all physical sensor types over the last decade. These sensors are reviewed here with detailed classification. In each case, associated technological challenges and comparisons with conventional counterparts are provided. Future directions and opportunities are highlighted.     

微系统用超声微电机的研究现状和发展趋势

 微电机是微机电系统(MEMS)的核心，超声微电机是一个新的发展方向．这几年发展十分迅速． 首先对比分析超声微电机与电磁型微电机和静电微电机的区别，对国内外现有的几种超声微电机及其发展趋势进行了介绍和分析，指出目前超声微电机发展存在研究定位不明和关键技术尚未完全解决两大问题。并提出了今后超声微电机发展的研究定位和必须解决的一些关键技术，其应用重点是军民两用，特别是军工． 最后，指出市场牵引和工程实现是超声微电机取得突破的关键因素的同时，政府、产业和研究单位各方面的重视和形成合力则是推进我国超声微电机研究和产业化的关键．     

Effect of the Drug–Excipient Ratio in Matrix-Type-Controlled Release Systems: Computer Simulation Study

The main objective of this work is to study the drug release behavior from inert matrix systems by using computer simulation. This study allowed us to propose a new statistical method to evaluate the drug percolation threshold as a function of the exposed surface area of the device. The matrix system was simulated as a simple cubic lattice. The sites of the lattice were randomly occupied at various drug–excipient ratios. By simulating a diffusive process, the drug was delivered from the matrix system. The obtained release profiles were fitted to two different models: near the excipient percolation threshold, the square root of the time was well fitted, whereas close to (but above) the drug percolation threshold, the power law described accurately the release data. A relationship between the initial drug load and the amount of drug trapped inside the matrix system at infinite time was found. This relationship was conveniently described by an error function. Percolation thresholds in the matrix systems were determined from the latter relationship by using a nonlinear regression method. The assessment of percolation thresholds depends on the exposed surface area of the matrix systems. Moreover, estimated percolation thresholds were in agreement with the predicted values stated in the percolation theory.     

硅微z轴谐振陀螺仪负电刚度效应 分析及实验验证

介绍了在开环工作状态下硅微z轴谐振陀螺仪由于加工工艺缺陷所导致的误差机理。为减小陀螺仪初始电容差和抑制正交耦合误差,提 出了一种闭环控制检测策略。重点分析 了其力矩反馈器的电刚度效应并给出其线性数学模型表示式。通过对硅微z轴陀螺仪敏 感模 态的反馈力与谐振频率的关系分析,间接得出了在敏感方向上电负刚度与力矩器所施电压的 内在联系,并在实验上进一步验证电刚度效应。这将为下一步闭环控制方案的设计奠定重要 基础。     

Controlled Release Camptothecin Tablets based on Pluronic and Poly(acrylic acid) Copolymer. Effect of Fabrication Technique on Drug Stability,Tablet Structure,and Release Mode

ABSTRACT

Poly(ethylene oxide)-b-poly(propylene oxide)-b-(polyethylene oxide)-g-poly(acrylic acid), a graft-comb copolymer of Pluronic® 127 and poly(acrylic acid) (Pluronic-PAA), was explored as an excipient for tablet dosage form of camptothecin (CPT). The tablets were prepared by either direct compression of the drug-polymer physical blend, suspension in ethanol followed by evaporation, or compression after kneading and characterized with respect to their physical structures, drug stability, and release behavior. Porosity and water uptake rate were strongly dependent on the fabrication procedure, ranking in the order: direct compression of physical blend > compression after suspension/evaporation in ethanol > compression after kneading. Tablets prepared by compression of physical blends swelled in water with a rapid surface gel layer formation that impeded swelling and disintegration of the tablets core. These tablets were able to sustain the CPT release for a period of time longer than those observed with the tablets made by either suspension/evaporation or kneading, which disintegrated within a few minutes. Despite the tablet disintegration, the CPT release was impeded for at least 6 hr, which was attributed to the ability of the Pluronic-PAA copolymers to form micellar aggregates at the hydrated surface of the particles. Physical mixing did not alter the fraction of CPT being in the pharmaceutically active lactone form, whilst the preparation of the tablets by the other two methods caused a significant reduction in the lactone form content. Tablets prepared from the physical blends demonstrated CPT release rates increasing with the pH due to the PAA ionization leading to the increase in the rate and extent of the tablet swelling. The results obtained demonstrate the potential of the Pluronic-PAA copolymers for the oral administration of chemotherapeutic agents.     

Effect of etchant concentration and defects on pyramid formation in TMAH etched silicon

An investigation on the effect of TMAH concentration on the etch rate of silicon, and the influence of etchant concentration, ambient temperature and wafer thermal history on the formation of pyramids at the surface of TMAH etched silicon has been carried out. From the results obtained from this study, we are able to explain the influence of TMAH concentration and ambient temperature on the silicon etch rate and the changes occurring at the silicon surface satisfactorily using the pH theory. However, the results from wafers with different thermal history seem to favour the defects theory. We suggest that in order to explain the etching mechanism of TMAH of silicon satisfactorily, a combination of pH and defects theories is necessary.