用于血样前处理的BioMEMS微流控芯片

基于BioMEMS技术,研制成三种血液样品前处理微流控芯片,分别介绍了血样前处理微流控芯片的原理、结构、制备技术以及样品前处理效果.基于错流过滤原理,设计了用于血细胞分离的错流过滤微结构,采用深刻蚀技术在硅片上刻蚀出直径为20μm,高度为50 μm的圆柱阵列;基于化学法破裂细胞,设计了用于血细胞破裂的夹流式微沟道,采用湿法腐蚀技术在硅片上腐蚀出深度约为80μm的微沟道;基于固相萃取原理,设计了用于DNA提纯的介孔固相载体,采用电化学阳极腐蚀技术在硅微沟道内表面制得表面积为300m2/g的介孔层.分别在芯片上实现了血细胞的分离、血细胞的破裂以及DNA的提纯.     

新型MEMS地震检波器的研究

以MEMS加速度传感器为基础的新型地震检波器大幅度提高了地震检波器的各项性能指标.介绍了一种新型的石油勘探MEMS地震检波器的设计及其主要技术参数,并通过微传感器结构的力学性能仿真,得出其具体的结构尺寸.经采用表面工艺和体工艺相结合的方法,利用磁控溅射、光刻、化学蚀刻及等离子体蚀刻等工艺,在高阻硅上制备出检波器样品.     

单硅片单面硅微机械加工的热温差流量传感器

在(111)硅片上研制了一种单硅片单面硅微机械加工的热温差式流量传感器.利用Comsol仿真软件对敏感结构参数进行优化设计,最大程度降低了传感器的热损耗,提高了传感器灵敏度和响应时间.此外,得益于MEMS微创手术MIS(Mi-cro-openings Inter-etch&Sealing)工艺技术使得加工后的芯片尺寸仅为0.7 mm×0.7 mm,测试结果表明:传感器灵敏度为107.88 mV/(m/s)W(无放大处理),检测响应时间仅为1.53 ms,综合精度为±4%.     

基于微模塑复制技术的平面线圈研制

作为硅微机械技术的替代,低成本的聚合物微制作变得越来越重要.在本研究中,开发了一种微模塑工艺,用以制作以聚合物为基底的平面线圈,将提高其可靠性,降低制造成本.双面密集微沟槽(100μm×70 μm)阵列是线圈基底的一大特点,其初始图形用MEMS技术刻制在硅片上;利用PDMS良好的柔性、弹性和复型分辨率的特性制作了过渡模版,通过图形转移技术成功解决了刚性脱模难的问题.探索出了中温注射、低温固化、高温后固化的最佳模塑成型方法.通过电铸,制得了厚度为0.7 mm、直径φ20 mm的平面微电机定子线圈.     

纳米二氧化硅的制备及表征

纳米二氧化硅具有奇异的物理、化学特性,它在生命科学与环境科学等领域有着广泛的应用.以水玻璃为原料,采用微乳液法和正丁醇共沸蒸馏法制备纳米级二氧化硅粉体.并通过扫描电镜、红外光谱分析,X射线衍射等手段对制备的纳米二氧化硅进行了表征.表征结果显示:制备的二氧化硅用扫描电镜观察,形态为近似球形,单体颗粒的粒径在几十纳米左右;X射线衍射图显示制备的纳米二氧化硅为无定形纳米二氧化硅.     

亚毫米多晶硅微齿轮的初步研制

自1989年美国加里弗尼亚大学报导采用IC技术首次成功地制作了微型静电电动机(转子直径为60μm和120μm)之后,以硅材料为主的微机械加工技术得到了世界各国科学家的高度重视和大力发展.微齿轮是微电动机的主要构件,通过它的研制,可以全面了解和     

硅牌键合技术的研究进展

硅片键合技术是指通过化学和物理作用将硅片与硅片、硅片与玻璃或其它材料紧密地结合起来的方法.硅片键合往往与表面硅加工和体硅加工相结合,用在MEMS的加工工艺中.常见的硅片键合技术包括金硅共熔键合、硅/玻璃静电键合、硅/硅直接键合以及玻璃焊料烧结等.文中将讨论这些键合技术的原理、工艺及优缺点.     

基于MEMS技术的异平面空心金属微针

MEMS微针的一个重要应用是透皮给药.文中提出了一种基于MEMS技术的异平面空心金属微针.该微针首先利用硅(100)面刻蚀技术在硅片上刻蚀出深度为330μm的倒四棱锥,然后采用电镀技术电镀出壁厚为50μm的空心金属倒四棱锥.从背面开出微流道并去除残余硅,就得到了倾斜角度为70.6°的异平面金属空心微针.最后采用ANSYS有限元仿真软件建立微针模型,验证了微针具有足够的强度.     

适用于RF MEMS能量耦合传输的高Q值电感

利用MEMS微电镀工艺技术制作了一种新型的适用于RF MEMS能量耦合传输的高Q值电感,采用ANSOFT公司的HFSS优化平面螺旋电感的结构。在具有高电阻率的玻璃衬底上溅射0.5μm的铜层作为下电极;PECVD淀积厚度为1μmSiO2作为中间介质层;在介质层上结合厚胶光刻技术电镀厚为22μm的铜作为电感线圈。这套电感制作工艺流程简单、易于与IC制备工艺集成。本文制备的微机械电感在微型植入系统中具有广阔的应用前景。测量结果表明:当工作频率在1GHz左右时,微电感的电感值达到55nH,Q值最大可达到25。     

基于吹塑成型方法的微玻璃空腔的设计与制备

根据硼硅酸盐玻璃的内部结构特殊性和热学性质,设计并制备出两种3D微玻璃空腔,主要讲述了3D微玻璃空腔的设计过程和吹塑成型的制备方法。 CORNING Pyrex 7740玻璃是硼硅酸盐玻璃的代表。将硅片进行深硅刻蚀形成深槽,并与7740玻璃进行常压下的阳极键合,形成微空腔;将得到的微空腔放入真空退火炉中进行退火,使玻璃空腔内部空气膨胀,最终形成3D微玻璃空腔。经过实验得到的两种3D微玻璃空腔表明其制备工艺的可行性,将制备出的3D微玻璃空腔运用到导航器件的设计和微结构的封装等方面,具有比较好的发展前景。     

Studies on SiC, DLC and TiO2 thin films as piezoresistive sensor materials for high temperature application

The use of thin films as sensing elements for microsensor applications has been shown very attractive due to their low-cost fabrication, potential for integration with standard CMOS technologies and possibility of deposition on different substrate types. In particular, piezoresistive sensors based on thin films have been commonly developed because can be easily implemented using microfabrication processes and present the best relation between sensitivity and system complexity, which showing great advantages in term of device integration. In our previous works (Fraga et al. 2010, 2011a), we studied undoped and nitrogen-doped PECVD a-SiC thin films as alternative materials to replace the silicon piezoresistors in strain and pressure sensors for harsh environments. Here, we focused our attention on the piezoresistive properties of sputtered silicon carbide (SiC), diamond-like carbon (DLC) and titanium dioxide (TiO₂) thin films. These materials were evaluated in terms of sensitivity or gauge factor and of the influence of the temperature on this sensitivity, allowing a preliminary analysis of the applicability of these thin films in high temperature piezoresistive sensors.     

硅基底和金刚石基底上沉积ZnO薄膜工艺研究

采用射频磁控溅射方法分别在硅基底和金刚石基底上制备ZnO薄膜,研究了硅和金刚石衬底的不同对ZnO薄膜生长机理的影响,同时分析了氩氧比和退火温度这两个工艺参数对薄膜的晶格取向和表面形貌的影响。利用XRD和AFM对ZnO压电薄膜的性能进行了测试。结果显示,金刚石基片上制备的薄膜表面状态远优于硅基片上的薄膜表面状态;在同类型基底上生长的ZnO薄膜,薄膜的晶格取向随着氩氧比的升高而增强;对于硅基底上生长的ZnO薄膜,适当的退火能够成倍地提高薄膜的c轴取向性。     

Development of AFM tensile test technique for evaluating mechanical properties of sub-micron thick DLC films

This paper describes mechanical properties of submicron thick diamond-like carbon (DLC) films used for surface modification in MEMS devices. A new compact tensile tester operating under an atomic force microscope (AFM) is developed to measure Young's modulus, Poisson's ratio and fracture strength of single crystal silicon (SCS) and DLC coated SCS (DLC/SCS) specimens. DLC films with a thickness ranging from 0.11 /spl mu/m to 0.58 /spl mu/m are deposited on 19-/spl mu/m-thick SCS substrate by plasma-enhanced chemical vapor deposition using a hot cathode penning ionization gauge discharge. Young's moduli of the DLC films deposited at bias voltages of -100 V and -300 V are found to be constant at 102 GPa and 121 GPa, respectively, regardless of film thickness. Poisson's ratio of DLC film is also independent of film thickness, whereas fracture strength of DLC/SCS specimens is inversely proportional to thickness. Raman spectroscopy analyses are performed to examine the effect of hydrogen content in DLC films on elastic properties. Raman spectra reveal that a reduction in hydrogen content in the films leads to better elastic properties. Finally, the proposed evaluation techniques are shown to be applicable to sub-micron thick DLC films by finite element analyses.     

多孔硅残余应力的研究

利用电化学腐蚀的方法在p型单晶硅(100)衬底上制备了多孔硅薄膜。利用微拉曼光谱法分别测量了处于湿化—干燥—再湿化3个阶段的多孔硅薄膜的拉曼频移,对多孔硅内应变引起的频移改变量和纳米硅晶粒因声子限制效应引起的频移改变量进行分离,找到多孔硅薄膜残余应力与拉曼频移之间的关系式。利用这一关系式,对不同孔隙率的多孔硅薄膜的残余应力进行了计算,获得了和声子模型拟合方法相一致的结果。研究中发现,多孔硅表面残余应力随孔隙率的增加而线性增大,其原因为随着孔隙率的增加,多孔硅晶格常数增大,且干燥过程中残液的蒸发产生的毛细应力使多孔硅薄膜与基体硅间晶格错配程度增大造成的。     

Deposition of Si-DLC film and its microstructural, tribological and corrosion properties

Silicon-incorporated diamond-like carbon (Si-DLC) films were deposited using a bipolar-type plasma based ion implantation and deposition technique, and the effects of Si-incorporation on the microstructural, tribological, anti-corrosion and lubricant bonding properties of the Si-DLC films were investigated. The analysis of Raman spectroscopy exhibited that the sp³ bonds in the DLC film increase due to Si addition. XPS analysis revealed that a thick oxide layer exists on the Si-DLC film surfaces. These explain the high lubricant bonding properties of the Si-DLC films compared to that of the Si-free DLC films. The silicon oxide layer on the Si-DLC film and the transferred silicon oxide layer on the steel ball prevents from the metal/DLC contact between the Si-DLC film and steel ball when sliding, which results in a low friction. Incorporation of Si in DLC films led to significant improvements in the corrosion resistance due to low internal stress and thick insulating oxide layer.     

Polycrystalline diamond pressure sensor

The piezoresistance and other characteristics of boron doped polycrystalline diamond films (PDF's) were determined by analyzing free-standing films that had been formed on silicon. These structures were adhered to a dielectric substrate, and from bending stresses a gauge factor was estimated. Subsequently, a monolithic all-diamond pressure sensor was designed and fabricated, whereby doped diamond resistors reside on a dielectric diamond substrate diaphragm. The process and piezoresistance behavior of their structure is described     

Silicon‐nanocrystal‐based photosensor integrated on low‐temperature polysilicon panels

Abstract— A photodetector using a silicon‐nanocrystal layer sandwiched between two electrodes is proposed and demonstrated on a glass substrate fabricated by low‐temperature poly‐silicon (LTPS) technology. Through post excimer‐laser annealing (ELA) of silicon‐rich oxide films, silicon nanocrystals formed between the bottom metal and top indium thin oxide (ITO) layers exhibit good uniformity, reliable optical response, and tunable absorption spectrum. Due to the quantum confinement effect leading to enhanced phonon‐assisted excitation, these silicon nanocrystals, less than 10 nm in diameter, promote electron‐hole‐pair generation in the photo‐sensing region as a result resembling a direct‐gap transition. The desired optical absorption spectrum can be obtained by determining the thickness and silicon concentration of the deposited silicon‐rich oxide films as well as the power of post laser annealing. In addition to obtaining a photosensitivity comparable to that of the p‐i‐n photodiode currently used in LTPS technology, the silicon‐nanocrystal‐based photosensor provides an effective backlight shielding by the bottom electrode made of molybdenum (Mo). Having a higher temperature tolerance for both the dark current and optical responsibility and maximizing the photosensing area in a pixel circuit by adopting a stack structure, this novel photosensor can be a promising candidate for realizing an optical touch function on a LTPS panel.     

Carbon nanotube based miniaturized electron gun and column assembly

We report on the application of silicon micromachining for the fabrication of miniaturized electron gun (MEG) assembly using vertically aligned carbon nanotubes. The proposed MEG consists of two main parts of electron gun and the accelerating column. While the electron gun consists of carbon nanotubes grown on a silicon substrate acting as an electron emission source, the accelerating column is made of micromachined silicon wafers with 5 μm thick membranes operating as objective lenses. These two wafers are placed together and sealed using a three-dimensional packaging technique. The simulation and experimental results show the evolution of a narrow electron beam by applying a proper voltage to the anodes and objective lens. The diverging and focusing of the beam can be controlled by applying the proper voltage on electrostatic lenses. This structure could be suitable for low energy SEM devices and surface physics applications.     

Thin-Film Piezoelectric Unimorph Actuator-Based Deformable Mirror With a Transferred Silicon Membrane

This paper describes a proof-of-concept deformable mirror (DM) technology, with a continuous single-crystal silicon membrane reflecting surface, based on$ PbZr _0.52 Ti_0.48 O _3$(PZT) unimorph membrane microactuators. A potential application for a terrestrial planet finder adaptive er is also discussed. The DM comprises a continuous, large-aperture, silicon membrane “transferred” onto a 20$,times,$20 piezoelectric unimorph actuator array. The actuator array was prepared on an electroded silicon substrate using chemical-solution-deposited 2-$mu m$-thick PZT films working in a$d _31$mode. The substrate was subsequently bulk-micromachined to create membrane structures with residual silicon acting as the passive layer in the actuator structure. A mathematical model simulated the membrane microactuator performance and aided in the optimization of membrane thicknesses and electrode geometries. Excellent agreement was obtained between the model and the experimental results. The resulting piezoelectric unimorph actuators with patterned PZT films produced large strokes at low voltages. A PZT unimorph actuator, 2.5 mm in diameter with optimized PZT/silicon thickness and design showed a deflection of 5.7$~mu m$at 20 V. A DM structure with a 20-$mu m$-thick silicon membrane mirror (50 mm$times,$50 mm area) supported by 400 PZT unimorph actuators was successfully fabricated and optically characterized. The measured maximum mirror deflection at 30 V was approximately 1$~mu m$. An assembled DM showed an operating frequency bandwidth of 30 kHz and an influence function of approximately 30%. 1738