基于牺牲层技术的高过载压力传感器芯片

提出了一种基于牺牲层技术的高过载压力传感器芯片。这种传感器充分利用了多晶硅机械特性和多晶硅纳米膜的压阻特性优势,提高了传感器满量程输出和过载能力。利用有限元方法设计了仿真模型,通过对弹性膜片应力分布的静态分析和非线性接触分析,给出了提高这种压力传感器满量程输出和过载能力的设计方法。并试制了量程为2.5 MPa的传感器芯片样品。测试结果表明样品的过载压力超过7倍量程,5 V供电条件下,满量程输出达到362 m V。     

一种大过载压差传感器结构研究

根据应用环境的要求,设计了一种大压力、大过载的小体积压差传感器.针对大过载压差传感器的结构特点,利用有限元分析软件,对传感器的关键部件进行了建模及优化设计.试验验证表明:压差传感器具有良好的大过载、耐恶劣环境的特性.     

一种大量程压力传感器的结构优化设计与仿真分析

设计了一种大量程硅压阻式压力传感器,通过理论模型分析优化传感器结构尺寸,保证薄膜的线性变化和抗过载能力;并通过有限元建模分析可动薄膜位移及应力随压力变化关系,对结构进行优化设计;同时用有限元仿真验证理论分析的正确性.通过理论与仿真优化分析,提出了采用C型膜片一体化硅压阻式压力传感器结构,可动薄膜选用方膜边长为1000μm,厚度为50μm,实现0~2 MPa的压力测量.     

抗高过载微压传感器

在提高微压传感器灵敏度的研究过程中 ,会遇到非线性和稳定性变差、过载能力不够以及静电封接时背岛与玻璃粘接造成器件失效等现象。提出了应力匀散结构和两层岛的限位结构 ,利用有限元分析和近似解析分析 ,设计了新的双岛 -梁 -膜结构 ,成功地研制出抗高过载微压传感器。量程为 0 .3kPa ,总精度为 0 .4% ,过载能力 >140倍满量程     

微型光纤光栅土压力传感器量程及其过载能力分析研究

为定量分析压力传感器的测量量程及其过载能力,提出一种微型光纤光栅土压力传感器并构建其气压标定系统。对微型光纤光栅土压力传感器进行理论分析得其灵敏度为7.5 nm/MPa,测量量程可达1.06 MPa。而分析光纤光栅土压力传感器性能测试数据得:该传感器压力灵敏度为5.9 nm/MP,线性度为99.93%,可测量实际量程为225 kPa,过载能力上限值为300 kPa。研究结果可用于指导设计规定量程的光纤光栅土压力传感器,具备一定应用价值。     

微型高温压力传感器芯片设计分析与优化

基于弹性力学和板壳力学理论,分析了微型高温压力传感器圆形膜片的受力分布,为力敏电阻在应变膜上的布置提供依据;利用有限元分析方法,借助ANSYS仿真软件,对微型高温压力传感器应变膜进行了一系列的分析和计算机模拟,探讨了传感器圆形应变膜简化应力模型的合理性以及温度对应力差分布的影响,得到了直观可靠的结果,为微型高温压力传感器芯片设计和研发新颖的微型高温压力传感器芯片提供有力的依据.     

高量程加速度传感器的结构优化与仿真分析

在传统双边四梁结构的基础上,优化设计了一种高量程加速度传感器结构,量程为10 000 gn。理论上对其进行了应力分析,验证了结构的合理性,并通过有限元建模对传感器进行了静态结构分析,模态分析和抗过载能力分析。在恒压源供电条件下,传感器的固有频率大于50 kHz,灵敏度理论值为18.88μV/gn,抗过载能力为20000 gn。与传统结构相比,极大地提高了高量程加速度传感器的性能。     

氮化硅薄膜传感器的平面加工工艺研究

介绍一种以氮化硅薄膜为压力敏感膜、多晶硅为电阻应变计的压力传感器。该压力传感器先后采用2种不同的平面加工工艺进行加工,实际结果表明:改进后的工艺比较好。通过采用对称分布在一个敏感膜上的4只多晶硅电阻应变计串联组成惠斯通电桥的一个桥臂,减少桥臂电阻的制作误差。制作传感器样品并对传感器的电压输出特性进行了测试。测试结果表明:恒流激励的传感器的电压输出特性非常好,传感器具有过载保护功能。     

厚膜压力传感器的结构优化

为提高厚膜压力传感器的稳定性,借助有限元分析软件Ansys,研究了厚膜压力传感器弹性体的应力分布,进而设计了应变电阻的尺寸,并优化了其布局。采用Ф18mm的96%A l2O3弹性体瓷件研制了一种新型厚膜力敏芯片,实验结果表明:它的热零点温漂小于3×10-4FS/℃,过载达120%,非线性误差及迟滞误差都小于±0.2%FS,精度由±0.4%FS提高到±0.2%FS,其线性度和稳定性得到很大提高,可广泛应用于仪器仪表、测控和导航等领域。     

自确认压力传感器结构参数设计及其有限元分析

设计了自确认压力传感器弹性体的结构参数,包括弹性体的材料选择,弹性体的形状、厚度和半径,建立了应变片在弹性体上的多组布片方案,为压力传感器实现自确认功能奠定了基础.应用有限元分析软件ANSYS对所设计的传感器弹性体进行了动、静态分析,获得了弹性体在受力情况下的位移、应力、应变分布状态,并且计算了弹性体的固有频率,分析结果表明,所设计的弹性体满足自确认压力传感器的设计要求.     

Polysilicon sacrificial layer etching using ClF3 for thin film encapsulation of silicon acceleration sensors with high aspect ratio

We present a new thin film encapsulation technique for surface micromachined sensors using a polysilicon multilayer process. The main feature of the encapsulation process is that both the sacrificial layer above the silicon sensor structure and the cap layer consist of epitaxial polysilicon. The sacrificial layer is removed by chlorine trifluoride (ClF₃) plasmaless gas-phase etching through vents within the cap layer. The perforated cap membrane is sealed by a nonconformal oxide deposition. The method has been applied to a silicon surface micromachined acceleration sensor with high aspect ratio structures, but is broadly applicable. Capacitance–voltage measurements have been performed to show the electrical functionality of the accelerometer.     

热驱动微型电场传感器干燥技术

介绍了热驱动微型电场传感器的工艺流程,主要介绍了微型电场传感器的释放干燥工艺.热驱动微型电场传感器工艺存在的最大问题是牺牲层释放以后容易产生粘连,为了避免粘连现象的产生,采用了不同的干燥方法,如蒸发干燥法、CO2临界点干燥法、自组装膜方法,并对这些方法的优缺点进行了比较.对不同干燥方法制备的热驱动微型电场传感器的性能进行了测试,得到自组装膜法制备的热驱动微型电场传感器具有更好的灵敏度.     

Sacrificial wafer bonding for planarization after very deep etching

A new technique is presented that provides planarization after a very deep etching step in silicon. This offers the possibility for resist spinning and layer patterning as well as realization of bridges or cantilevers across deep holes or grooves. The sacrificial wafer bonding technique contains a wafer bond step followed by an etch back. Results of polymer bonding followed by dry etching and anodic bonding combined with KOH etching are discussed. The polymer bonding has been applied in a strain based membrane pressure sensor to pattern the strain gauges and to provide electrical connections across a deep corrugation in a thin silicon nitride membrane by metal bridges     

LIGA技术及其在制造可动微结构件中的应用

介绍了将LIGA技术及其与牺牲层技术相结合 ,制造可动微结构的工艺方法。并给出了可实现摆动、转动的可动微结构———微执行器、微传感器和三维加速度传感器的制造过程等应用实例     

Modification of the oxygen diffusivity in limiting current oxygen sensors

Effect of sacrificial carbon on microstructure of protective layer and sensing properties of limiting current oxygen sensors were studied. Graphite and carbon nanofiber with different concentrations were examined as sacrificial layer. Therefore, several YSZ-based electrochemical gas sensors were fabricated with dissimilarity in the diffusivity of the layer covering their measuring electrodes.Gas sensors were tested as potentiometric and amperometric devices under O₂-N₂ mixtures, and synthetic gases similar to the exhaust gas mixtures from combustion engines. Sensors with low diffusivity (low concentration of sacrificial material) exhibit more abrupt and O₂-sensitive potentiometric responses. Indeed, less O₂-linear amperometric responses and higher response times are their characteristics. Sensors with high diffusion in their layers (high concentration of sacrificial material) show a less abrupt step-drop potentiometric response but a more linear O₂ dependence for the amperometric response and, in general, lower response times.Results suggest that the configuration of the diffusive layer shall be controlled in terms of the expected performance of the sensor, as an amperometric or potentiometric device. The controlling parameters are discussed and given in this study.     

Fabrication and flow-sensor application of flexible thermal MEMS device based on Cu on polyimide substrate

A Cu on polyimide (COP) substrate was proposed as a MEMS material, and the fabrication process for a flexible thermal MEMS sensor was developed. The COP substrate application to MEMS devices has the advantage that typical MEMS structures fabricated in a SOI wafer in the past—such as a diaphragm, a beam, a heater formed on a diaphragm—can also be easily produced in the COP substrate in the flexible fashion. These structures can be used as the sensing element in various physical sensors, such as flow, acceleration, and shear stress sensors. A flexible thermal MEMS sensor was produced by using a lift-off process and sacrificial etching of a copper layer on the COP substrate. A metal film working as a flow sensing element was formed on a thin polyimide membrane produced by the sacrificial etching. The fabricated flexible thermal MEMS sensor was used as a flow sensor, and its characteristics were evaluated. The obtained sensor output versus the flow rate curve closely matched the approximate curve derived using King’s law. The rising and falling response times obtained were 0.50 and 0.67 s, respectively.

     

基于SOI-MEMS工艺的谐振式压力传感器研究

提出了一种电磁激励、差分检测的谐振式MEMS压力传感器,该器件采用低电阻率的SOI器件层单晶硅制作“H”型谐振梁,并作为激励和检测电极。根据对传感器数学模型的分析,利用有限元分析方法优化了传感器结构设计。采用等离子深刻蚀制作传感器结构,并用湿法腐蚀SOI二氧化硅层的方法释放。利用硅-玻璃阳极键合技术,实现了传感器的圆片级真空封装。采用开环扫描检测和闭环自激振荡方式,测定压力传感器的特性。实验结果表明：传感器一致性良好,在500~1100hPa的检测范围内,差分检测灵敏度为14.96Hz/hPa,线性相关系数为0.999996。     

Releasing high aspect ratio SU-8 microstructures using AZ photoresist as a sacrificial layer on metallized Si substrates

This paper presents a successful method for releasing high aspect ratio SU-8 micro-structures by the use of positive photoresist (AZ 4620) as sacrificial layer. The AZ 4620 photoresist sacrificial layer was dissolved by the SU-8 developer (propylene glycol monomethyl ether acetate). Thus, this process reduces the need for complex microfabrication steps and equipments which are otherwise required in traditional methods using metal sacrificial layers. The current method is both cost-effective and time-effective because no additional releasing method or material is needed to remove the fabricated SU-8 structures. Further, the influence of surface energy on the adhesion between Si and SU-8 was demonstrated and metallic thin layer coating on Si was employed to further reduce the lift-off duration. The results obtained showed that the duration for lift-off of SU-8 structures from metal (Al) coated Si substrate is much lower (approximately 90 % time saving) and the surface morphology of the released structures has lesser micropore concentration compared to the process employing bare Si as the substrate. In both processes AZ 4620 was the sacrificial layer whereas the metalized Si substrate could be re-used.     

Preparation of sacrificial layer for MEMS devices by lift-off technology

To simplify the preparation of sacrificial layer in micro-electromechanical system structure, new processes have been developed. By using lift-off technology, sacrificial layer was selectively deposited into the pit that prepared for sacrificial layer releasing. Then a short time polishing process was used to remove the burrs around the pit. This method offers several advantages including reducing the difficulty of polishing and hence processing cost. Methods and apparatuses to provide a continuously smoothly sacrificial layer surface in the pit were disclosed. However, it is important to control the homogeneity of filling and avoid the shadow effect at the corner of the pit. The unpadded regions would form a steep step and cause the cracking of structure layer. This problem was discussed and solved by rotating the tilted wafer during sacrificial material deposition. The surface roughness after the preparation process of sacrificial layer was measured. The root mean square roughness of sacrificial layer was 1.247 nm and reduced to 0.861 nm after a short time polishing process. Finally, a film bulk acoustic wave resonator with stacked Mo/AlN/Mo films had been fabricated on the sacrificial layer based on this method.