基于聚酰亚胺柔性衬底微温度传感器阵列的关键技术研究

基于柔性MEMS技术,在聚酰亚胺柔性衬底上成功制作出8×8阵列的铂薄膜电阻微温度传感器.该器件特别适用于复杂几何体高曲率表面温度的实时监控.采用了两种方法制作柔性器件第一种方法是将液态聚酰亚胺旋涂在有氧化物牺牲层的载体硅片上;第二种方法是用胶粘剂将P16051膜暂时粘在载体硅片上,然后分别在两种柔性PI衬底上制作铂薄膜热敏电阻温度传感器,最后将器件从硅片载体上分离下来.采用低温(小于300℃)工艺技术减小了PI柔性衬底的热循环.实验测试结果表明,PI衬底上的铂薄膜热敏电阻具备良好的线性度,其电阻温度系数接近于0.0023/℃.     

基于ZnO压电薄膜的柔性声表面波器件

提出并制备了基于聚酰亚胺柔性衬底的声表面波(SAW)器件。在柔性聚酰亚胺衬底上低温反应磁控溅射沉积了ZnO压电薄膜;采用X射线衍射仪,扫描电子显微镜,原子力显微镜等设备对ZnO薄膜进行了检测,结果表明:ZnO薄膜晶粒呈柱状生长并且(002)择优取向,膜粗糙度小于9nm,适合制作压电器件。在柔性衬底上制备了基于ZnO压电薄膜的SAW器件,该器件表现出良好的谐振性能。采用矢量网络分析仪检测器件的传输曲线,实验结果与仿真结果具有很好的一致性。随着波长减小,谐振频率和相速度增加,当ZnO厚度为4μm,波长为8μm时,器件的谐振频率为268MHz,相速度为2 144m/s,机电耦合系数为1.1%;当ZnO厚度增加时,此叠层结构的声表面器件的叠层声速也增加。     

聚酰亚胺柔性温度传感器的制作与性能测试

基于微机电系统技术,在柔性聚酰亚胺(PI)基底上分别制作弓形与蛇形两种结构的铜薄膜与铂薄膜温度传感器。采用红外成像设备对传感器在通电状态下的热分布进行测试,结果表明PI基底具有良好的热绝缘性。对不同结构、不同金属薄膜的传感器性能进行对比分析,在25～90℃的温度测试范围内,4种温度传感器均具有较好的灵敏度和线性度,其中蛇形结构的铂薄膜温度传感器的线性度最好,线性相关系数达到了0.99933,其电阻温度系数为0.002 35/℃。     

柔性声表面波器件的波模式分析

用反应磁控溅射法在柔性聚酰亚胺衬底上沉积了ZnO压电薄膜,并制备了基于ZnO压电薄膜的柔性声表面波(SAW)器件。制备的柔性SAW器件显示了良好的谐振性能,而且展现出两个波模式:模式0和模式1。当波长为32μm,ZnO厚度为4μm时,SAW器件的模式0和模式1的谐振频率分别为34.4MHz和158.5MHz,对应声速为1 100.8m/s和5 072m/s。模式0为已知的瑞利波,模式1为新的高频模式。沉积了不同厚度的ZnO薄膜制备柔性SAW器件,进一步分析了薄膜厚度对SAW器件和模式1的影响。分析认为该高频模式不是传统硬质衬底上SAW器件产生的Sezawa波,而是S_0兰姆波,并且是有衬底情况下的S_0兰姆波。文中还采用Comsol仿真分析了新的高频模式1的粒子振动位移,结果和S_0兰姆波粒子振动位移一致,从而验证了其为广义兰姆波的正确性。     

衬底温度对低温制备铜铟镓硒薄膜结晶性能的影响

采用低温三步共蒸发法在柔性聚酰亚胺衬底上制备了铜铟镓硒(CIGSe)薄膜,利用扫描电子显微镜和X射线衍射仪表征了CIGSe薄膜的结晶质量和晶体结构,探讨了低温沉积工艺中第二步和第三步衬底温度与薄膜晶粒尺寸、织构取向和结晶性能的关系。结果表明:随着第二步和第三步衬底温度同时升高,CIGSe薄膜的晶粒尺寸逐渐增大,镓的两相分离现象逐渐消失;保持第二步衬底温度不变,随着第三步衬底温度进一步升高,CIGSe薄膜的晶粒尺寸继续增大,薄膜的结晶质量显著改善;第二步和第三步衬底温度的变化对CIGSe薄膜的织构取向基本没有影响。     

聚酰亚胺薄膜的反应离子刻蚀抛光

为进一步提高聚酰亚胺薄膜光学器件的表面质量,提出了一种聚酰亚胺薄膜的反应离子刻蚀抛光方法,对其抛光原理和抛光实验进行了研究。利用光刻胶流体的低表面张力及流动特性,通过在聚酰亚胺薄膜表面涂覆光刻胶对其表面缺陷进行填补;结合聚酰亚胺与光刻胶的反应离子高各向异性等比刻蚀工艺,将光刻胶光滑平整表面高保真刻蚀转移至聚酰亚胺表面,从而实现聚酰亚胺薄膜的反应离子刻蚀抛光。实验结果表明:PV、RMS分别为1.347μm和340nm的粗糙表面,通过二次抛光其粗糙度可降低至75nm和13nm;PV、RMS分别为61nm和8nm的表面,其粗糙度可降低至9nm和1nm。该抛光方法能有效提高聚酰亚胺薄膜的表面光洁度,可为以聚酰亚胺薄膜为代表的高分子柔性光学器件的精密加工提供新的工艺思路。     

聚酰亚胺薄膜的反应离子刻蚀抛光方法

为进一步提高聚酰亚胺薄膜光学器件的表面质量,提出了一种聚酰亚胺薄膜的反应离子刻蚀抛光方法,对其抛光原理和抛光实验进行了研究。利用光刻胶流体低表面张力及流动特性,通过在聚酰亚胺薄膜表面涂覆光刻胶对其表面缺陷进行填补;结合聚酰亚胺与光刻胶的反应离子高各向异性等比刻蚀工艺,将光刻胶光滑平整表面高保真刻蚀转移至聚酰亚胺表面,从而实现聚酰亚胺薄膜的反应离子刻蚀抛光。实验结果表明：PV、RMS分别为1.347μm和340nm的粗糙表面通过二次抛光可降低至75nm和13nm,PV、RMS分别为61nm和8nm的表面粗糙度可降低至9nm和1nm。该抛光方法能有效提高聚酰亚胺薄膜的表面光洁度,可为以聚酰亚胺薄膜为代表的高分子柔性光学器件的精密加工提供新的工艺思路。     

旋涂新方法可制备高性能电子薄膜

<正>美国密苏里科技大学的研究者发现了一种制备薄膜的新方法,用这种方法生产的薄膜性能优异,可用于制造太阳能电池、柔性电池或LED半导体。单晶形态的薄膜具有较好的光学和电子学性质,但制备起来较为困难,成本高昂、技术复杂。在实际工业生产中,往往会采用成本更低的旋涂方法,即在液体旋转过程中制备光滑的薄膜,溶液层接触到衬底后会变     

微型柔性热敏传感器阵列应用研究

边界层分离点检测是实现分离流主动控制的前提和基础，也是气动控制灵巧蒙皮系统研究的重点和难点。以流体边界层分离点检测技术为研究对象，以流体边界层分离点判定的风洞实验为验证目标，设计制作微型热敏传感器与聚酰亚胺柔性衬底，并首次利用微装配技术集成分立敏感元件与柔性衬底形成热敏传感器阵列。首先，采用分立元件通过表面贴装工艺来实现柔性微型热膜传感器阵列的集成，并研究该传感器阵列中敏感元件、柔性衬底的设计及传感器的排布。然后，在低速风洞实验中对传感器阵列的性能和传感器阵列输出信号采用统计量算法的方式进行处理判断，判定圆柱翼型的流体分离点位置。最后，对实验的结果所作的分析表明，该微型柔性热敏传感器阵列满足流体分离检测系统实时性、动态性的要求。     

衬底对溶胶-凝胶法制备ZnO压电薄膜的影响

采用溶胶-凝胶法分别在晶态衬底Si/SiO2/Ti/Pt和无定形态衬底Si/SiO2上制备了ZnO压电薄膜.以X射线衍射仪和原子力显微镜研究了薄膜的002择优取向度和表面形貌.结果表明,采用溶胶-凝胶法在Si/SiO2/Ti/Pt和Si/SiO2衬底上都能制备出具有较好择优取向,表面粗糙度低的ZnO薄膜,而且由于Pt和ZnO的晶格失配度较小,在Si/SiO2/Ti/Pt衬底上生长的ZnO薄膜形成002择优取向的退火温度低于在Si/SiO2衬底上生长的薄膜形成002择优取向的退火温度.     

The electrostatic-alloy bonding technique used in MEMS

Electrostatic-alloy bonding of silicon wafer with glass deposited by Au to form Si/Au-glass water, and bonding of Si/Au-glass with silicon wafer were researched during fabrication of pressure sensors. The silicon wafer and glass wafer with an Au film resistor were bonded by electrostatic bonding, and then Si-Au alloy bonding was formed by annealing at 400°C for 2 h. The air sealability of the cavity after bonding was finally tested using the N₂ filling method. The results indicate that large bond strength was obtained at the bonding interface. This process was used in fabricating a pressure sensor with a sandwich structure. The results indicate that the sensor presented better performances and that the bonding techniques can be used in MEMS packaging. __________ Translated from Journal of Harbin Institute of Technology, 2005, 37(1) (in Chinese)     

A study on the characteristics of a wafer-polishing process according to machining conditions

The polishing process for silicon wafers plays a key role in the fabrication of semiconductors, since a globally planar, mirrorlike wafer surface is achieved in the process. The surface roughness of the wafer depends on the surface properties of the carrier head unit, together with other machining conditions, such as working speed, type of polishing pad, temperature, and down force. In this paper, the results of several experiments are used to study silicon wafer surfaces. The experiments were designed to observe the down force and temperature when a wafer carrier head unit with wafer was pressed down onto a polishing pad. A load cell was employed to detect the applied pressure against the polishing pad, and the working temperature was measured with an infrared sensor. Wafer surface roughness was investigated according to several parameters and experimental data.     

An automated laser thermometer for studying plasma processes in the microtechnology

The design and characteristics of an automated temperature sensor of dielectric and semiconductor substrates in apparatuses for film deposition and etching of microstructures are considered. The temperature is measured via the laser interference thermometry technique as wavelengths of 0.633 and 1.15 μm of a He-Ne laser. A signal-to-noise ratio of ～30 dB attained in the system is such that the device is sensitive to a change in the substrate temperature of 0.01 K. The heating and cooling of the wafer are recognized automatically and displayed via a graphic interface in real time. An interferogram recorded during substrate heating or cooling, the time dependence of the temperature after the discharge initiation, and the temperature dependence of the substrate-heating power are displayed on the monitor. For 0.5-mm-thick silicon substrates, the measurement range at a wavelength of 1.15 μm extends from cryogenic temperatures to 650 K.     

A 32 × 32 temperature and tactile sensing array using PI-copper films

The development of a flexible 32?×?32 temperature and tactile sensing array, which will serve as the artificial skin for robot applications, is presented in this work. Pressure conductive rubber is employed as the tactile sensing material, and discrete temperature sensor chips are employed as the temperature sensing cells. Small disks of pressure conductive rubber are bonded on predefined interdigital copper electrode pairs which are patterned on a flexible copper–polyimide substrate which is fabricated by micromachining techniques. This approach can effectively reduce the crosstalk between each tactile sensing element. The mechanical and electrical properties of tactile sensing elements are measured. Also, the corresponding scanning circuits are designed and implemented. The temperature and tactile sensing elements are heterogeneously integrated on the flexible substrate. By using the integrated 32?×?32 sensing arrays, temperature and tactile images induced by the heaters/stamps of different shapes have been successfully measured. The flexible sensor arrays are bendable down to a 4-mm radius without any degradation in functionality.     

Electro-magnetically actuated valveless micropump with two flexible diaphragms

We present a parallel dynamic passive valveless micropump, which consists of three layers-valve, diaphragm and electromagnetic coil. The valve is wetly etched in a silicon wafer, the diaphragm is a polydimethyl siloxane (PDMS) film spun on a silicon wafer with embedded permanent magnet posts, and the coil is electroplated on a silicon substrate. Under the actuation of the magnetic field of the coil, the flexible diaphragm can be displaced upwards and downwards. After analyzing magnetic and mechanical characteristic of the flexible membrane and direction-dependence of the nozzle, this paper designed a micropump. And the relative length (L/d) of the micropump's nozzle is 4. A 7×7 array of permanent magnetic posts is embedded in the PDMS film. Two diaphragms work in an anti-step mode, which can relieve the liquid shock and increase the discharge of the micropump. ANSYS and Matlab are adopted to analyze the actuation effect of the coil and the flow characteristic of the micropump. Results show that when actuated under a 0.3 A, 100 Hz current, the displacement of the diaphragm is more than 30 μm, and the discharge of the micropump is about 6 μL/s.     

Design and development of resistive temperature detector arrays on aluminium substrates. Measurements in mixing experiments

Incomplete mixing of fluids of different temperatures generates thermal striping, which is to date difficult to accurately predict. For metal piping the induced temperature fluctuations are harmful, because they lead to thermal fatigue. This phenomenon is significant in nuclear power plant safety considerations, in particular in connection with aging of the equipment. This work contributes to the current research effort by presenting an array of resistive temperature detectors (RTDs) based on a micro patterned thin film platinum resistor for experimental studies of the thermal impact to the wall. The sensors are located on an aluminium substrate, on which the platinum resistors and the electrical contact leads are embedded. The operational temperature range is below 0 °C up to 180 °C (in air), the temperature coefficient of resistivity (TCR) is 0.0014 °C⁻¹ with a high linear correlation coefficient. The thermal time constant has been measured and studied using a one-dimensional finite element method. This sensor was applied in a test facility where two water streams of different temperatures and the same flow speed blend downstream of the rear edge of a splitter plate in a horizontal rectangular channel. It was used to measure and characterize in terms of frequency and amplitude the thermal fluctuations generated by the contact of the mixing patterns developed in the bulk of the flow with the channel side walls.     

Development of a tactile sensor array with flexible structure using piezoelectric film

This research is the development of a flexible tactile sensor array for service robots using PVDF(polyvinylidene fluoride) film for the detection of a contact state in real time. The prototype of the tactile sensor which has 8X8 array using PVDF film was fabricated. In the fabrication procedure, the electrode patterns and the common electrode of the thin conductive tape were attached to both sides of the 28/im thickness PVDF film using conductive adhesive. The sensor was covered with polyester film for insulation and attached to the rubber base for a stable structure. The proposed fabrication method is simple and easy to make the sensor. The sensor has the advantages in the implementing for practical applications because its structure is flexible and the shape of the each tactile element can be designed arbitrarily. The signals of a contact force to the tactile sensor were sensed and processed in the DSP system in which the signals are digitized and filtered. Finally, the signals were integrated for taking the force profile. The processed signals of the output of the sensor were visualized in a personal computer, and the shape and force distribution of the contact object were obtained. The reasonable performance for the detection of the contact state was verified through the sensing examples.     

Research and design of a novel,low-cost and flexible tactile sensor array

At present, the flexible tactile sensor array has become a hot research topic in the field of robotics. This paper introduces the design, fabrication and measurement of a novel tactile sensor array based on soft materials and sensor’s piezoresistivity. This sensor array is capable of detecting the contact force and contact location via a triangular location algorithm. This triangular algorithm, which uses response of different sensing elements to a contact force, can reduce the amount of processing data and the density of the sensor array can get lower. The flexible pressure sensing elements are integrated in a flexible PDMS (polydimethylsiloxane) film, which can avoid the limitation that traditional rigid sensing elements have during their bending deformation. The sensor array’s performance has been experimentally evaluated. The results show that the proposed sensor array has an accuracy of 88.23% for the force and spatial resolution of the sensor array can reach 2.5 mm.     

全柔性热膜微传感器阵列制造工艺及性能优化

利用MEMS微加工技术,以镍作为热敏材料,在柔性衬底上制作出了全柔性热膜微传感器阵列,具有软性可弯、便于曲面贴附实现分布测量、高灵敏度的特点。结合制备工艺与性能测试,首次系统性分析掌握了氩气压强、衬底温度、溅射功率、退火温度等工艺参数对电阻温度系数的影响规律。通过优化工艺参数以提高柔性热膜微传感器的电阻温度系数,使其达到了4640 ppm/℃,并且保持了较好的线性度。     

基于柔性传感器阵列的边界层分离位置测定实验研究

结合边界层分离点附近的剪应力变化规律，提出针对在飞行器外表面贴附微型传感器的分离点检测方法，给出了相应微型剪应力传感器阵列的设计方案。研制了在柔性聚酰亚胺衬底集成微型热敏传感器的柔性传感器阵列，解决了柔性传感器阵列对微细加工工艺要求较高的难题。在低速风洞实验中对传感器阵列的性能和传感器阵列输出信号的处理判断方式进行了验证，实验结果分析表明，研制的微型热敏传感器阵列能够实现对流体边界层分离位置的在线测量。