硅微陀螺仪的误差分析

以z轴硅微陀螺仪为研究对象,对加工误差产生的误差信号进行了分析.由于加工误差,使得陀螺仪结构不对称,主要表现为支承梁不对称、梳齿间距不等,产生了不等弹性、阻尼不对称以及力不平衡这三种现象.以动力学方程为基础,分析了不等弹性和阻尼不对称产生的误差信号;以静电理论为基础,分析了驱动梳齿和敏感梳齿间距不等时产生的误差信号.分析结果表明,这些误差信号包含了正交耦合误差和与有用信号同相位的误差信号.最后,介绍了一种减小正交误差的方法,并进行了仿真.     

基于BOE硅腐蚀现象的硅纳米线制作

介绍一种硅纳米线制作方法.在SOI顶层硅上制作硅纳米梁,通过离子注入形成pnp结构,利用新发现的没有特殊光照时BOE溶液腐蚀pn结n型区域现象,结合BOE溶液氧化硅腐蚀,实现硅纳米线制作.制作完全采用传统MEMS工艺,具有工艺简单,成本低,可控,可靠性好,可批量制作等优点.利用该方法制作出了厚50 nm,宽100 nm的单晶硅纳米线,制作的纳米线可用于一维纳米结构电学性能研究、谐振器研究等.     

利用MEMS技术研制硅脉象传感器

利用MEMS技术在N型<100>晶向的单晶硅衬底上设计并制作了以纳米硅/单晶硅异质结为源极和漏极的P-MOSFETs脉象传感器.在方形硅膜上制作四个以纳米硅/单晶硅异质结为源极和漏极P-MOSFETs,并将P-MOSFETs的沟道电阻设计成惠斯通电桥结构,从而实现对微小脉象信号的准确检测.实验结果表明,该硅脉象传感器在恒压源-3.0 V供电条件下,灵敏度为1.623 mV/kPa,准确度为2.029%F·S.     

An extended model of design process of lean production systems by means of process variables

In this paper, we present an axiomatic modeling of lean production system design, using process variables (PVs). So far, we had developed a model for conceptual design of lean production systems by means of FR–DP relationships, the key characteristics of axiomatic design (AD) methodology, appeared in the proceedings of Second International Conference of Axiomatic Design. Albeit the model in question was thorough enough to be applied in various cases, its embedded abstract principles hamper straightforward applications and the required resources, tools, and techniques are not clarified. In AD terms, it lacks PVs created by mapping the design parameters (DPs) to the process domain to clarify the means that produce the specified DPs. Owing to the difficulties involved in the definition of PVs for manufacturing systems, there is few works in this area. This paper is an attempt to introduce PVs in production system design. When we are developing a product (i.e. a part), we can simply interpret the set of PVs as the process design. In the case of a production system we interpret PVs as the tools, methods, and resources, required for implementing a lean production system. In this paper, according to AD methodology, we have developed a hierarchical structure to model the design process of a lean production system, composed of FRs, DPs, and PVs. Serving as an efficient guideline for the design process and clarifying the required tools, methods, and resources, this structure is general enough to be applied for different cases.     

The surface/bulk micromachining (SBM) process: a new method forfabricating released MEMS in single crystal silicon

This paper presents the surface/bulk micromachining (SBM) process to allow fabricating released microelectromechanical systems using bulk silicon. The process starts with a (111)-oriented silicon wafer. The structural patterns are defined using the reactive ion etching technique used in surface micromachining. Then the patterns, as well as sidewalls, are passivated with an oxide film, and bare silicon is exposed at desired areas. The exposed bare silicon is further reactive ion etched, which defines sacrificial gap dimensions. The final release is accomplished by undercutting the exposed bulk silicon sidewalls in aqueous alkaline etchants. Because {111} planes are used as etch stops, very clean structural surfaces can be obtained. Using the SBM process, 5-, 10-, and 100-μm-thick arbitrarily-shaped single crystal silicon structures, including comb-drive resonators, at 5-, 30-, and 100-μm sacrificial gaps, respectively, are fabricated. An electrostatic actuation method using p-n junction isolation is also developed in this paper, and it is applied to actuate comb-drive resonators. The leakage current and junction capacitance of the reversed-biased p-n junction diodes are also found to be sufficiently small for sensor applications. The developed SBM process is a plausible alternative to the existing micromachining methods in fabricating microsensors and microactuators, with the advantage of using single crystal silicon     

A micromachined tunable resonator fabricated by the CMOS post-process of etching silicon dioxide

This work investigates the fabrication of a micromechanical tunable resonator using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-process of only one maskless wet etching. The post-process has advantages of easy execution and low cost. The post-process employs an etchant (silox vapox III) to etch the silicon dioxide layer to release the suspended structures of the resonator. The tunable resonator comprises a driving unit, a tuning unit and a sensing unit. The resonant frequency of the resonator can be tuned using a dc-biased electrostatic comb of linearly varied finger-length. Experimental results show that the resonant frequency of the resonator is about 4.8 kHz, and it has a frequency-tuning range of 6.8% at the tuning voltage of 0–25 V.     

Microplastic lens array fabricated by a hot intrusion process

A microplastic lens array has been successfully constructed on top of a 500-/spl mu/m-thick PC (Polycarbonate film) by using a micro hot intrusion process. A single-layer LIGA process is used to fabricate the high-aspect-ratio nickel mold insert that has circular hole patterns of 80 /spl mu/m in diameter and 200 /spl mu/m in depth. Under the hot intrusion process, plastic material can be intruded into these circular-shape holes and stopped at desired depth under elevated temperature and pressure to fabricate microlenses. By adjusting the embossing load, temperature and time, the curvature and height of the lens are controllable when the same mold insert is used. The optical properties of these microlenses have been characterized and the average radius of curvature is found as 41.4 /spl mu/m with a standard deviation of 1.05 /spl mu/m. Experimental characterization and theoretical model are conducted and developed for the micro-intrusion process in terms of the radius of curvature and height of the lenses and they correspond well with experimental data within 5% of variations. The focusing capability of the lenses is demonstrated by comparing the images of laser light with and without using the lenses. When the projection screen is placed 200 /spl mu/m away from the lens, the full-width at half-maximum (FWHM) for the lens is 110 /spl mu/m while the original FWHM of the optical fiber is 300 /spl mu/m.     

Polymer micro valve with a hydraulic piezo-drive fabricated by the AMANDA process

A normally-closed piezo-driven micro valve for gases and liquids has been developed. Due to the small deflection of piezo-actuated bending disks made of PZT a hydraulic transmission was constructed, which increases the displacement of the piezo disk up to the 25-fold. The switching times of the valve are shorter than 1.8 ms.

Silicone gel serves as a transition medium in the hydraulic. It simplifies the manufacturing process and allows a flexible adaptation to different pressure requirements up to a differential pressure of 150 kPa switched with 300 V. Additionally, this silicone gel supports the sealing of the valve so it achieves an open-to-close ratio of 1:150,000 or higher.

The overall dimensions of the valve are 13 mm×13 mm×3 mm, the dead volume is 0.33 μl, and the inner diameter of the valve seat is 200 μm. A transformer as small as the micro valve is able to produce driving voltages of up to 300 V with a response time of 2 ms. Therefore, the valve could be integrated into hand-held systems which are battery powered with 5–15 V.     

High performance flat miniature heat pipes fabricated by UD-LIGA process

 The objective of this work is to process a high performance flat miniature heat pipes (FMHP). The FMHP is fabricated by ultra-deep LIGA (UD-LIGA) process developed by SRRC. Moreover, the performance of the FMHP is theoretically estimated. The dimensions of microgrooves on the FMHP are 1 mm in depth, 100 μm in width, and 60 mm in length. The theoretically predicted results show that the dissipated heat flux can reach to 391 W at a working temperature of 100 °C. Received: 10 August 2001/Accepted: 24 September 2001 This paper was presented at the Fourth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2001 in June 2001.     

A circular micromirror array fabricated by a maskless post-CMOS process

This work studies the fabrication of a circular micromirror array by the standard 0.35 m SPFM (Single Polysilicon Four Metals) CMOS (complementary metal oxide semiconductor) process and a maskless postprocess. The advantages of the post-process are its compatibility with conventional CMOS process and this method provides a way to designer to quickly construct micromachined structures using the standardized procedures. The mentioned circular micromirror array that contains 10 × 10 micromirror switches is integrated with a 1 × 8 de-multiplexer control circuit and a four-stage charge pump on a chip. The radius of each micromirror is about 25 ìm, and the gap from the bottom electrode to the top mirror plate is about 5 m. The micromirror array is actuated using an electrostatic force. Simulated results show that the micromirror has a tilting angle of around 9° at a driving voltage of 30 V. The root-mean-square roughness and the average roughness of the mirror surface are measured at 15.31 nm and 12.58 nm respectively. In addition, the first and the second mode of natural frequency of the micromirror switch are around 492 KHz and 508 KHz, respectively.The authors would like to thank Song-Nan Chen, Yao-Tian Huang of the Institute of Applied Mechanics, National Taiwan University, Professors Lung-Jieh Yang, and Chien-Liu Chang for their valuable advice and assistance in experiment. In addition, we would, finally, like to thank the NSC Northern Region MEMS Research Center, the National Chip Implementation Center and the National Center for High-performance Computing for kindly making their complete research facilities available.     

Scanning micromirrors fabricated by an SOI/SOI wafer-bonding process

MEMS scanning micromirrors have been proposed to steer a modulated laser beam in order to establish secure optical links between rapidly moving platforms. An SOI/SOI wafer-bonding process has been developed to fabricate scanning micromirrors using lateral actuation. The process is an extension of established SOI technology and can be used to fabricate stacked high-aspect-ratio structures with well-controlled thicknesses. Fabricated one-axis micromirrors scan up to 21.8/spl deg/ optically under a dc actuation voltage of 75.0 V, and have a resonant frequency of 3.6 kHz. Fabricated two-axis micromirrors scan up to 15.9/spl deg/ optically on the inner axis at 71.8 V and 13.2/spl deg/ on the outer axis at 71.2 V. The micromirrors are observed to be quite durable and resistant to shocks. Torsional beams with T-shaped cross sections are introduced to replace rectangular torsional beams in two-axis MEMS micromirrors, in order to reduce the cross-coupling between the two axial rotations. Fabricated bidirectional two-axis micromirrors scan up to /spl plusmn/7/spl deg/ on the outer-axis and from -3/spl deg/ to 7/spl deg/ on the inner-axis under dc actuation.     

Micro-punching process of stainless steel foil with micro-die fabricated by micro-EDM

Micro-punching has become a potential micro-manufacturing process due to the simplicity of the process, low cost, high production capability and accuracy. But the size of a punched micro-hole is limited due to the difficulties of tool fabrication. In the paper, we propose a design procedure according to buckling theory and a kind of micro-die fabrication method for micro-punching process. Micro-punch and female die with high dimensional accuracy were fabricated by micro-EDM with block electrode. Micro-punching processes of stainless steel foil were conducted with the micro-punch and female die equipped in the precision micro-punching tool. Micro-holes of 300, 150 and 100 μm in diameter were pierced with a good profile and high dimensional accuracy, which indicate that the micro-die fabricated by micro-EDM is suitable for micro-punching processes.     

Development of lighting panel comprising light tube fabricated by LIGA process

A new lighting panel consists of the light tube that shifts a point light source (light emitting diode) to line light source, and the light guide plate that shifts light from the light tube to surface illuminant. The light tube has length of 27.5 mm and has thickness of 1.0 mm, and width has the light incidence part of 2.6 mm, and it narrows toward the tip. On one side of the light tube, there are a lot of very small prisms that reflect light to the other side. The dimensions of the light guide plate are 30.0 mm × 30.0 mm × 1.0 mm and the reflection dots are arranged in a range of 27.0 mm × 27.0 mm. The bottom surface of the light guide plate is fitted with numerous truncated-cone-shaped reflection dots, and the light that comes out from the light tube reflects in them and comes out of the upper part of the light guide plate. We designed, fabricated, and evaluated the lighting panel by using LIGA process and UV-LIGA process.     

2-DOF vibratory gyroscope fabricated by SU-8 based UV-LIGA process

This paper reports fabrication of 2-DOF vibratory gyroscope using SU-8 based UV-LIGA process. The device structure is designed to be symmetrical in order to match the resonance frequencies of drive and sense mode oscillators and also to minimize their relative temperature dependent drift. The overall arrangement is such that the two vibration modes do not affect each other and therefore, mechanical decoupling is achieved which helps in minimizing bias drift. The design is optimized to be compatible with the UV-LIGA process having 10 μm thick electroformed nickel as structural layer. Photolithography to create 11 μm thick SU-8 molds for electroforming sacrificial copper and structural nickel layer is optimized using multiple exposure technique that ensures near vertical side walls. Since the highly cross-linked SU-8 remaining after development is difficult to remove reliably from high aspect ratio structures without damage or alteration to the electroformed metals, a 2.45 GHz MW plasma etching process is developed with CF₄/O₂ mixes. The fabricated device is checked for off-plane misalignment between the stationary and movable comb fingers using white light interferometry and it is found to be almost negligible. Also, the prototype device is characterized for amplitude and phase spectral responses using Polytec MSA-500 Micro System Analyzer. The drive and sense mode resonance frequencies are observed at 7.3 and 7.1 kHz respectively against the mode matched designed frequency of 7.5 kHz.     

Formalizing the repair process — extended report

This paper defines the model-based diagnosis and repair process. We consider repair (i.e. restoration of specified system purposes) as the main goal of this process. Our goal is to define how an intelligent agent integrates and schedules observations and actions in an interleaved way in order to guarantee a specifiedsystem purpose. We define a temporal framework where all concepts necessary to represent repair (actual, possible and plausible worlds, purpose, observations, actions and failures) can be integrated. Using these concepts we present an algorithm scheme describing the repair process.Most of this work was carried out while the author was a member of the Christian Doppler Laboratory for Expert Systems     

Thermal conductivity measurement of submicrometer-scale silicon dioxide films by an extended micro-Raman method

The micro-Raman method is a noncontact and nondestructive method for thin film thermal conductivity measurements. To apply the micro-Raman method, however, the thickness of the film must be at least tens of micrometers. An analytical heat transfer model is presented in this work to extend the micro-Raman measurement method to measure the thermal conductivity of thin films with submicrometer- or nanometer-scale thickness. The model describes the heat transfer process in the thin film and substrate considering the effects of thin film thickness, interface thermal resistance, thermal conductivity of the thin film and substrate. From this heat transfer model, an analytical expression for the thermal conductivity of the thin film is derived. Experiments were successfully performed to measure the thermal conductivity of 200, 300 and 500 nm thickness silicon dioxide films using the extended micro-Raman measurement method, with results confirming the accuracy and validity of the extended model.     

An extended model for remaining time prediction in manufacturing systems using process mining

The ability to predict the remaining cycle-time in industrial environments is of major concern among production managers. An accurate prediction would enable managers to handle undesired situations with more control, thereby preventing future losses. However, making such predictions is no trivial task: there are many methods available to cope with this problem, including a recent research stream in process mining. Process mining provides tools for automated discovery of process models from event logs, and eventually, extend those models in driving predictions. In general, predictive models in process mining generally deals with business processes, and not directly with the industrial environment, which contains a full prism of particularities. In this paper we propose a hybrid predictive model based on transition-systems and statistical regression which is “product-oriented”, tailored to better predict online cycle-times on industrial environments. We propose a weight for each method, optimized by a linear programming model. We tested our new approach on an artificially created log that emulates an industrial environment, and on a real manufacture log. Results showed that our approach provides better accuracy measures for both test instances.     

An extended iterative format for the progressive-iteration approximation

Progressive-iteration approximation (PIA) is a new data fitting technique developed recently for blending curves and surfaces. Taking the given data points as the initial control points, PIA constructs a series of fitting curves (surfaces) by adjusting the control points iteratively, while the limit curve (surface) interpolates the data points. More importantly, progressive-iteration approximation has the local property, that is, the limit curve (surface) can interpolate a subset of data points by just adjusting a part of corresponding control points, and remaining others unchanged. However, the current PIA format requires that the number of the control points equals that of the data points, thus making the PIA technique inappropriate to fitting large scale data points. To overcome this drawback, in this paper, we develop an extended PIA (EPIA) format, which allows that the number of the control points is less than that of the given data points. Moreover, since the main computations of EPIA are independent, they can be performed in parallel efficiently, with storage requirement O(n), where n is the number of the control points. Therefore, due to its local property and parallel computing capability, the EPIA technique has great potential in large scale data fitting. Specifically, by the EPIA format, we develop an incremental data fitting algorithm in this paper. In addition, some examples are demonstrated in this paper, all implemented by the parallel computing toolbox of Matlab, and run on a PC with a four-core CPU.