“中国微米纳米”一种低温制备的高灵敏度MEMS电容传声器

MEMS传声器是将声音信号转换成电信号的传感器.目前,MEMS传声器的研究主要涉及 MEMS电容传声器和MEMS压电传声器压阻传感器2种.与其它类型的MEMS传声器相比,MEMS电容传声器具有高灵敏度、高信噪比、频率响应平坦、低温度系数等突出的优点,被广泛使用在便携式设备、多媒体系统、助听器、信息采集等方面.设计和制备了一种高灵敏度的MEMS电容传声器,而且制备器件的工艺温度最高为300 ℃,可以兼容IC工艺.在本文,利用牺牲层的方法实现圆形振动薄膜,避免了方形薄膜存在的应力集中问题,并克服了干法制备圆形薄膜成本高的问题.基于聚酰亚胺材料,优化成膜工艺参数,实现低应力的圆形振动薄膜.通过设计防粘连结构,避免器件释放干燥过程中出现的薄膜粘连问题.根据振动膜应力为5 MPa,半径为2.5 mm,厚度为1 μm,电极半径为380 μm,间隙为1 μm的设计参数进行理论计算,该器件的电容在1 Pa 声压下的变化量为千分之一.与市场流通的MEMS传声器相比,高出约一个数量级,可被用于远场拾音,从信噪比极低的环境中拾取关键的声音信息.     

一种具有广泛适应性的微机械加工方法研究

研究了一种具有广泛适应性的微机械制造方法,该方法可用于制备各种不同的器件,包括硅微陀螺仪、加速度计、剪切应力传感器以及光开关等.利用该方法,制备了硅微陀螺仪,并给出了所制备的硅微陀螺仪的性能测试结果,同时分析了利用该制备方法制备各种不同器件时,工艺流程对器件性能的影响,重点讨论了硅-玻璃阳极键合、减薄工艺以及深刻蚀所形成的侧壁质量,包括侧壁垂直度、侧壁杂质等因素对器件性能的影响.     

MEMS陀螺芯片的晶圆级真空封装

微机电系统(MEMS)陀螺需要真空封装以确保其检测精度,晶圆级真空封装可以使MEMS微结构避免芯片切割过程中的粘连以及颗粒污染,提高芯片的成品率.为实现MEMS陀螺芯片的晶圆级真空封装,提出了一种全硅MEMS陀螺芯片的晶圆级真空封装结构方案,并突破了Si-SiO2直接键合、吸气剂制备、金—硅(Au-Si)键合等关键技术...     

硅微机械陀螺仪结构中的电容分析

为减小杂散电容提高信噪比,分析了硅微机械陀螺仪结构中的电容.并以某硅微机械陀螺仪的理论模型为对象,建立了陀螺仪结构中的电容模型.对每种电容进行了理论分析,并借助电路仿真软件对模型进行了仿真,分析了杂散电容对输出的影响,结果表明布线与活动结构间的电容对输出有很大的影响.提出了采用新工艺和合理的布线方法减小与活动结构间的电容,从而提高信噪比.     

集成微流体测控芯片的研制

设计、研制了集成有微泵、微沟道、微流量传感器、温度传感器的微流体测控芯片.采用有限元软件ANSYS模拟分析了将其作为冷却芯片时微沟道的散热作用,分析确定了芯片上各元件的结构.该集成芯片为硅-玻璃结构,在硅片上,利用ICP法刻蚀无阀微泵泵体和微沟道;在7740玻璃片上,以溅射、剥离法制作微流量和温度传感器;图形精确对准后硅/玻璃以静电键合方法封接.无阀微泵采用压电元件驱动.测试结果表明:集成芯片具有冷却功能,循环水的流速最大可达25.4mm/s.     

旋转摆动式硅微机械陀螺敏感头的研制

介绍旋转摆动式硅微机械陀螺电容敏感的原理,给出了陀螺振动单元的结构尺寸,计算了被测角速度和敏感电容的关系,进而得到被测角速度和输出电压的关系.利用微机械加工方法加工得到了硅振动单元,加工硅振动单元的工艺特点是双面多次光刻、腐蚀.介绍了制作旋转摆动式硅微机械陀螺敏感元件的工艺并对制作的敏感元件进行测试,测试结果表明“三明治“敏感元件四个敏感电容较计算得到的电容偏小.     

基于硅膜的电容式高灵敏度低频传声器研究

在电容式传声器相关理论以及方形膜研究的基础上,采用圆形硅膜作为振动膜,研制了电容式低频传声器,该传声器直接采用音频传声器结构,不同于以往的电容式低频传声器结构.首先进行了等效结构参数的仿真,为实验提供了理论支持;然后,制备了直径为0.08 m,厚度约60μm的圆形硅膜,并以此硅膜为振动膜研发了一种高灵敏度的低频传声器,其中,两极板间的气隙厚度约为100 μm.测试表明,当偏置电压为4.5 V时,该传声器具有较高的灵敏度,100 Hz处的灵敏度约为-27dB,通频带(20～300 Hz)平坦,低频响应部分(0～20 Hz)需要改进方法进一步测试.     

（中国微米纳米技术学会文章）一种硅微机械结构振动幅度的电学测量方法及实验研究

本文针对硅微机械结构振动幅度由于封装难以计算机视觉测量及电学测量中的精度受接口电路参数影响的问题,在对静电梳齿驱动、平板电容检测的硅微谐振结构进行建模分析后,提出基于单边带电压比的电学测量振动幅度的方法并分析了测量方法的原理。实验表明研制的某硅微机械谐振加速度计在受迫振动下的振动幅度为0.25um,频谱分析还表明存在上电噪声引起的振动幅度,该测试方法还能应用于硅微谐振结构的谐振频率测量,同时为高品质因数的硅微机械谐振结构的可静电自激驱动提供了依据。     

圆形振动膜硅微电容传声器

硅微传声器是一种用MEMS技术制造的、将声信号转换为电信号的声学传感器.该传声器只需五次光刻工艺即可制作完成,其灵敏度在偏置电压为9V时可达15mV/Pa左右,在100Hz～18kHz的范围内的频率响应也较平坦.     

用于软光刻的恒温实验台的设计

介绍了一种可用于软光刻操作的恒温实验台的设计与实现.在一个密闭的小型箱体中集成了温度与压力控制、照明及紫外光照、操作手套等组件,可以实现无尘、恒温、压力可控、紫外光照等多种功能.在该恒温实验台中,利用聚二甲基硅氧烷进行微传递模塑实验研究,考察了温度、压力等对聚二甲基硅氧烷成模特性的影响.同时,还利用聚二甲基硅氧烷与聚亚胺脂的两次复制完成了硅微芯片结构向玻璃基底的转移.研究结果表明:这一新的实验研究平台可以实现恒温、无尘操作、一定的真空度以及紫外照射,满足普通实验室进行微传递模塑等软光刻操作的要求.     

Capacitive microphone with a surface micromachined backplate usingelectroplating technology

A technology for surface micromachining of free-standing metal microstructures using metal electrodeposition on a sacrificial photoresist layer has been applied to a condenser microphone. Electroplating technology has been used to implement a suspended and perforated 15-μm-thick microstructure in copper, which serves as backplate electrode in the condenser microphone. The 1.8×1.8 mm ² large microphone diaphragm is in monocrystalline silicon and is fabricated with anisotropic etching of the substrate wafer. The realized prototypes have a measured sensitivity of 1.4 mV/Pa using a bias voltage of 28 V. The bandwidth is limited by an anti-resonance at 14 kHz which is due to the semi-rigid backplate. The resonance behavior of the backplate structure has been analyzed with finite element modeling with results in good agreement with measured data     

具有自由悬浮敏感膜的硅微机械电容式麦克风的设计与仿真计算

提出了一种具有自由悬浮敏感膜和带孔铜底板的硅微机械电容式麦克风.采用低压化学汽相淀积工艺制作而成的复合敏感膜一端固定于硅基,其余部分处于自由悬浮状态,可以释放敏感膜的内应力.底板采用铜电镀技术制作,底板上呈蜂窝状分布的圆形通气孔用来调节敏感膜与底板间的空气压膜阻尼.仿真计算表明在5 V偏置电压下麦克风灵敏度为10.62 mV/Pa,工作稳定最大电压为9.7 V,工作频率带宽为0～10.57 kHz.分析结果表明该微机械麦克风能满足市场需求.     

工业化硅微机械电容式麦克风的设计与性能计算

给出了一种单芯片硅微机械电容式麦克风的结构设计,并针对此结构对其进行了动态特性分析计算。硅微机械电容式麦克风的两个电极由一个复合敏感膜和一个金属铜底板构成。复合敏感膜包括三层,中间一层是掺杂硼的多晶硅,上下两层是氮化硅,三层复合膜的厚度设计和制作工艺使复合膜处于轻微的拉应力状态。底板采用低温电镀铜技术制作,底板上分布有许多圆形通气孔来调节敏感膜与底板间的空气压膜阻尼。在复合敏感膜和金属铜底板之间采用牺牲层技术制作了一空气间隙,使复合敏感膜和一个金属铜底板之间构成一工作电容。在硅基体的背面采用湿法腐蚀出声音进口腔。针对这一结构我们对其动态特性进行了分析计算,计算出麦克风在9V偏置电压下开环灵敏度为4.99mV/Pa,麦克风最大偏置电压为32.83V,麦克风工作时的频率带宽为0~134kHz。分析结果表明该硅微机械电容式麦克风能满足工业界的使用要求。     

Fabrication of silicon condenser microphones using single wafertechnology

A condenser microphone design that can be fabricated using the sacrificial layer technique is proposed and tested. The microphone backplate is a 1-μm plasma-enhanced chemical-vapor-deposited (PECVD) silicon nitride film with a high density of acoustic holes (120-525 holes/mm²), covered with a thin Ti/Au electrode. Microphones with a flat frequency response between 100 Hz and 14 kHz and a sensitivity of typically 1-2 mV/Pa have been fabricated in a reproducible way. These sensitivities can be achieved using a relatively low bias voltage of 6-16 V. The measured sensitivities and bandwidths are comparable to those of other silicon microphones with highly perforated backplates. The major advantage of the new microphone design is that it can be fabricated on a single wafer so that no bonding techniques are required     

Improvement of the performance of microphones with a silicon nitride diaphragm and backplate

The performance of a single-wafer fabricated silicon condenser microphone has been improved by increasing the stress and the acoustic hole density of the backplate and by decreasing the diaphragm thickness. The best microphones show a sensitivity of 5.0 mV Pa⁻¹, which corresponds to an open-circuit sensitivity of 10 mV Pa⁻¹ for a microphone capacitance of 6.6 pF. The measured frequency response is flat within ±2 dB from 100 Hz to 14 kHz, which is better than the requirements for a hearing-aid microphone. The operating voltage of these microphones is only 5.0 V, which is about 60% of the collapse voltage. The measured noise level of the microphones is 30 dBA SPL, which is approximately as low as required for a hearing-aid microphone ( <29.5 dBA SPL).     

Design and fabrication of silicon condenser microphone usingcorrugated diaphragm technique

A novel silicon condenser microphone with a corrugated diaphragm has been proposed, designed, fabricated and tested. The microphone is fabricated on a single wafer by use of silicon anisotropic etching and sacrificial layer etching techniques, so that no bonding techniques are required. The introduction of corrugations has greatly increased the mechanical sensitivities of the microphone diaphragms due to the reduction of the initial stress in the thin films, For the purpose of further decreasing the thin film stress, composite diaphragms consisting of multilayer (polySi/Si_xN_y/polySi) materials have been fabricated, reducing the initial stress to a much lower level of about 70 MPa in tension. Three types of corrugation placements and several corrugation depths in a diaphragm area of 1 mm² have been designed and fabricated. Microphones with flat frequency response between 100 Hz and 8~16 kHz and open-circuit sensitivities as high as 8.1~14.2 mV/Pa under the bias voltages of 10~25 V have been fabricated in a reproducible way. The experimental results proved that the corrugation technique is promising for silicon condenser microphone     

A Micromachined Dual-Backplate Capacitive Microphone for Aeroacoustic Measurements

This paper presents the development of a micro-machined dual-backplate capacitive microphone for aeroacoustic measurements. The device theory, fabrication, and characterization are discussed. The microphone is fabricated using the five-layer planarized-polysilicon SUMMiT V process at Sandia National Laboratories. The microphone consists of a 0.46-mm-diameter 2.25-mum-thick circular diaphragm and two circular backplates. The diaphragm is separated from each backplate by a 2-mum air gap. Experimental characterization of the microphone shows a sensitivity of 390 muV/Pa. The dynamic range of the microphone interfaced with a charge amplifier extends from the noise floor of 41 dB/ radicHz up to 164 dB and the resonant frequency is 178 kHz.     

High-performance condenser microphone with fully integrated CMOSamplifier and DC-DC voltage converter

The development of a capacitive microphone with an integrated detection circuit is described. The condenser microphone is made by micromachining of polyimide on silicon. Therefore, the structure can be realized by postprocessing on substrates containing integrated circuits (IC's), independently of the IC process, integrated microphones with excellent performances have been realized on a CMOS substrate containing dc-dc voltage converters and preamplifiers. The measured sensitivity of the integrated condenser microphone was 10 mV/Pa, and the equivalent noise level (ENL) was 27 dB(A) re. 20 μPa for a power supply voltage of 1.9 V, which was measured with no bias voltage applied to the microphone. Furthermore, a back chamber of infinite volume was used in all reported measurements and simulations     

A FCOB packaged thermal wind sensor with compensation

A two dimensional wind sensor was designed, fabricated and packaged on ceramic substrate instead of silicon substrate. The Ti/Pt heater and thermistors were fabricated using single lift-off process. The gold bumps were then sputtered and patterned on the chip using lift-off process again. Correspondingly, the Pb/Sn bumps were fabricated on the FR4 substrate using stencil printing method after metallization. The sensor chip was flip-chip packaged on the FR4 substrate, and the gap was filled with epoxy-based underfill to improve the structure strength. The packaged sensor was tested in wind tunnel in constant power mode. The wind velocity and direction offsets of the sensor were compensated using software and hardware calibration. Both the simulation and test results show that the thermal wind sensor can measure wind speeds up to 8 m/s with an accuracy of 0.3 m/s, and wind direction in a full range of 360° with a resolution within 5°.