ITEM METADATA RECORD
Title: Development of complex micro-devices: design, fabrciation technologies and reliability study
Authors: Ferraris, Eleonora
Issue Date: May-2006
Abstract: It is widely recognized that the microsystem technology field brings relevant technological breakthroughs and social benefits. It aims the developing of advanced systems whose operation normally combined two or more of the following properties: electrical, mechanical, optical, biological or others, integrated onto a monolithic or hybrid miniaturized structure. Thus, the technological trends of multifunctional integration and miniaturisation are the key points of this new discipline.

This works deals with investigating the problematic in development, fabrication and reliability of microsystems with particular attention to complex devices. Specifically, the complex terms refers to the following: silicon based micro-systems containing advanced mechanical components and kinematic architecture enabling the accurate positioning of an end-effector; micro-systems constituted by several components requiring specific materials and 3D variable shaping, and then assembled. Moreover, the present book aims to evaluate potentialities and manufacture feasibility of PKM (Parallel Kinematic Machine) at millimetre and sub-millimetre scale.

In micro applications, two distinct technology solutions can be distinguished. At micro scale, silicon is the most common material as it combines unique electrical and mechanical properties suitable for accomplishing the based functional principles of a micro product. Moreover, the production capabilities of microelectronic foundry can be exploited as well as the batch characteristic for cost effective solutions. This approach leads to a monolithic system with nearly 2D ½ layout and overall package of few mm3. Among the main applications, there are accelerometers, pressure sensors and optical micro switching, which involve the oscillation and the deformation of simple mechanical elements as proof mass, beams and cantilever. The challenge here is to establish the production of complex mechanical components and kinematic architectures (as PKM) for the development of advanced mechanical systems. On the other hand, hybrid approach conceive the product as constitute by several parts assembled together, with the further issue of choosing the most appropriate material and production technologies for each component. As far as concerns the creating, the handling and the flexible assembly of 3D micro sized components, hybrid solution is intrinsic a complex task and the scaling down of existing manufacturing and product principles reach their limits and lead to ineffective industrial solutions. In this context, the feasibility of complex hybrid ceramic and metal-based micro systems is deeply investigated.

The present book comprises three principal parts.

The first one introduces the microtechnology field. The benefits derived by the miniaturisation and the functional integration are illustrated. Moreover, the most significant factors involved in developing a micro product are illustrated. Furthermore, the most promising fabrication technologies, with particular attention to those that allow the developing of complex micro-devices and the problematic in scaling down the existing fabrication concepts are illustrated. Finally, micro assembly technologies are briefly reviewed. These topics take place in Chapter I.

The second part more concerns the investigation of silicon-based solutions. In Chapter II, particular attention is paid to the industrial feasibility of complex micro devices. The study involves the following tasks: prototyping of a micro-hinge anchored to the substrate; development of a 1 DoF multi-body device with planar motion; feasibility study of a multi DoF compliance systems, based on PK architecture, enabling the out of plane positioning of an end-effector. Successively, Chapter III addresses the reliability study of micro electromechanical systems under cyclic loading. The study becomes even more urgent when complex compliance configurations are chosen. The development of an experimental set-up for performing the fatigue test is presented. Moreover, the Woehler parameters of the 15 m thick epitaxial polysilicon are defined. The activities are performed at the MEMS Business Unit of STMicroelectronics, currently the Italian leader company in producing silicon-based products and within the European MACROS (Modelling And Characterization for Reliability Of Silicon MEMS) project.

The third part finally deals with potential and limitations in scaling down conventional processes to develop ceramic and metal based complex hybrid solutions. Chapter IV addresses the application of spark erosion processes for machining 3D micro-components in ceramic composites. The production performance is investigated in details and the roughing–finishing technological parameters are defined. The activities are performed within the Power MEMS Belgian project at the Micro Precision Engineering (MPE) Research Group, Mechanical Engineering Department of the Catholic University of Leuven. The research input is given by the fabrication of micro turbines for fuel based micro power generators. Then, Chapter V deals with the manufacture feasibility using micro cutting processes of a 2 DoF micro mechanism based on parallel kinematic architecture and multi body configuration, with promising applications in the high precision positioning field. The activities are performed within the MEPROMEC project, -Development and industrial application of tools and methodology for the mechatronic design-, founded by the province of Trento, Italy, at the Institute of the Industrial Technologies and Automation of the National Research Council of Italy. The study highlights the critical issues in manufacturing and assembly complex hybrid microsystems, and points out the importance of developing properly clamping units and rough pieces based on Design for Production and Design for Assembly concepts in order to improve the machining accuracy, the handling tasks and the functional integration.

Finally, in Chapter VI conclusions and future works are drawn.
Table of Contents: SOMMARIO 1
SUMMERY 3
CONTENTS 5
CHAPTER I: MICROTECHNOLOGY: STATE OF THE ART. 9
1. DEFINITION OF MICROPRODUCT. 9
2. BENEFITS OF MICROTECHNOLOGY AND SCALE EFFECTS. 12
2.1. Changes in physics: the input for new solutions. 12
2.2.1. New materials. 13
2.2.2. New working principles for actuators. 13
2.2.3. New generation of sensors. 14
2.2.4. New manipulation systems. 15
2.2.5. New concepts for mechanical design. 15
3. APPLICATION FIELDS AND MAIN TRENDS. 17
3.1. Potentialities of Parallel Kinematic Machine (PKM) in microtechnology. 25
4. DEVELOPMENT PROCESS OF A MICROPRODUCT. 29
4.1. Product-Process descriptive level relationships. 30
4.2. Physical descriptive level. 31
4.3. Inherent coupling nature characteristic. 32
4.4. Modelling process of a microproduct. 33
4.4.1. Layout & Design. 34
4.4.2. Process Simulation. 34
4.4.3. Device Simulation. 35
4.4.4. System Simulation. 35
4.4.5. Verification. 36
5. FABRICATION TECHNOLOGIES. 37
5.1 Silicon Technologies. 37
5.1.1. Silicon: the structural material of MEMS. 37
5.1.2. Basic process steps in machining silicon. 39
5.1.2.1. Lithography. 39
5.1.2.2. Wet etching. 40
5.1.2.3. Dry etching. 41
5.1.2.4. Film growth and layer deposition. 43
5.1.3. Bulk micromachining technology. 45
5.1.4. Surface micromachining technology. 46
5.2. Micro Engineering Technologies. 49
5.2.1. Micro cutting processes. 51
5.2.2. Micro EDM processes. 54
5.2.3. Micro LBM processes. 57
5.2.4. Micro electrochemical processes. 58
5.2.3. Micro solidification processes. 59
5.2.5. Micro forming processes. 59
5.3. LIGA Technology. 61
5.4. Closing remarks on fabrication technologies. 62
6. MICROASSEMBLY. 64
6.1. From macro to micro domain 64
6.1.1. Physics of micro world. 64
6.1.2. Process automation aspects. 67
6.1.3. Product design aspects. 68
6.2. Micro assembly techniques. 69
6.2.1. Contact and contact-less manipulation. 69
6.2.2. Serial micro assembly techniques. 73
6.2.3. Parallel micro assembly techniques. 75
6.2.4. Joining. 77
6.3. 3D assembly of silicon surface micromachined structures. 80
6.4. Closing remarks on micro assembly. 83
7. MICRO FACTORY. 85
8. CONCLUSION AND RESEARCH OBJECTIVES. 87
CHAPTER II: DEVELOPMENT AND INDUSTRIAL FEASIBILITY OF COMPLEX -ELECTROMECHANICAL SYSTEMS. 90
1. INTRODUCTION. 90
2. DESCRIPTION OF THE THELMATM TECHNOLOGY. 92
3. INDUSTRIAL PROTOTYPING OF MICRO HINGES. 97
4. INDUSTRIAL FEASIBILITY AND REALIBILITY OF COMPLEX MICRO DEVICES: DISCUSSION. 102
5. DEVELOPMENT OF 1DOF MULTI BODY-BASED MICRO DEVICE. 106
5.1. Design of the electrostatic engine. 107
5.1.1 Design of comb-finger actuators: theoretical background. 109
5.1.1.1 Failure mechanisms of comb-finger actuators. 111
5.1.2. Engine dimensioning. 113
5.2. Design of the supporting serpentine springs. 115
5.3. Device/System simulation. 117
5.4. Test and verification. 119
5.4.1. Capacitance-based procedure for the static characterisation of MEMS devices. 119
5.4.2. LDV-based procedure for the dynamic characterisation of MEMS devices. 122
5.4.3. Reliability test of multi body-based MEMS devices. 126
6. FEASIBILITY STUDY OF A MULTI DOF COMPLIANCE BASED MICRO PKM. 128
7. CONCLUSION. 135
CHAPTER III: RELIABILITY STUDY ON FATIGUE FAILURE OF MEMS DEVICE. 138
1. INTRODUCTION. 138
2. DESCRIPTION OF THE TEST DEVICE AND OPERATIONAL STUDY. 140
2.1. System-Device simulation. 141
2.2. Test and verification. 143
2.3. Electromechanical physical model of the test device. 146
3. DESCRIPTION OF THE TEST BED SET-UP: FROM SINGLE TO MASS CHARACTERISATION. 149
4. EXPERIMENTAL RESULTS. 156
5. CRITICAL DISCUSSION ON DYNAMIC FATIGUE OF SILICON. 159
6. DEVELOPMENT OF A NEW FATIGUE TEST DEVICE BASED ON NOTCH LAYOUT 163
6.1. Design. 163
6.2. Test and verification. 169
7. CONCLUSION. 172
CHAPTER IV: EDM PROCESS DEVELOPMENT FOR CERAMIC -COMPONENT MANUFACTURING. 175
1. INTRODUCTION. 175
2. MICRO-ENGINEERING APPLICATION OF CERAMIC COMPOSITES. 176
3. SI3N4-TIN CERAMIC EDM INVESTIGATION. 179
3.1. Definition of EDM technological parameters in roughing mode. 181
3.1.1. Further investigation on pulse parameter conditions. 186
3.2. Definition of EDM technological parameters in finishing mode. 188
4. SURFACE QUALITY OPTIMISATION OF THE EDM LAYER OF SI3N4-TIN. 193
5. PRELIMINARY APPLICATION OF THE OBTAINED TECHNOLOGICAL PARAMETERS. 197
6. CONCLUSION. 200
CHAPTER V: FEASIBILITY STUDY OF COMPLEX HYBRID -SYSTEMS BASED ON CONVENTIONAL CUTTING PROCESSES. 204
1. INTRODUCTION. 204
2. DESCRIPTION OF THE CASE OF STUDY: DEVELOPMENT OF A MICRO PKM. 206
3. DESIGN FOR MANUFACTURING AND ASSEMBLY. 209
3.1. Geometrical design of the leg, the platform and the join components. 209
4. PROCESS SIMULATION: MANUFACTURING AND ASSEMBLY OF THE SYSTEM. 213
4.1. Leg -joint component manufacturing. 213
4.2. Platform and universal joint components manufacturing. 215
4.3. Assembly of the revolute and of the universal joints. 217
5. CONCLUSION. 219
CHAPTER VI: CONCLUSION. 222
1. CONCLUSION. 222
REFERENCES 228
APPENDIX A: FATIGUE TEST-BED: DESCRIPTION OF THE ELECTRONIC BOARD COMPONENTS. 236
APPENDIX B: NOTCH BASED FATIGUE-TEST MEMS DEVICE: PARAMETRIC FEM MODEL. 243
APPENDIX C: DEVELOPMENT OF A MINI PKM: DRAFTING OF THE MAIN MECHANICAL COMPONENTS. 248
APPENDIX D: DEVELOPMENT OF A MINI PKM: PART PROGRAM OF THE LEG-JOINT COMPONENT. 251
Publication status: published
KU Leuven publication type: TH
Appears in Collections:Production Engineering, Machine Design and Automation (PMA) Section
Mechanical Engineering Technology TC, Technology Campus De Nayer Sint-Katelijne-Waver
Technologiecluster Werktuigkundige Industriële Ingenieurstechnieken

Files in This Item:

There are no files associated with this item.

Request a copy

 




All items in Lirias are protected by copyright, with all rights reserved.