NANO-ELECTRO-MECHANICAL SWITCH (NEMS) FOR ULTRA- LOW POWER PORTABLE EMBEDDED SYSTEM APPLICATIONS ANALYSIS, DESIGN, MODELING, AND CIRCUIT SIMULATION By KHAWLA ALZOUBI Submitted in partial fulfillment of the requirements For the degree of Doctor of Philosophy Dissertation Advisor: Prof. Daniel Saab Dissertation Co-Advisor: Prof. Massood Tabib-Azar Department of Electrical and Computer Science CASE WESTERN RESERVE UNIVERSITY AUGUST, 2010 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the dissertation of Khawla Alzoubi candidate for the Ph.D degree*. (signed) Daniel Saab (chair of committee) Massood Tabib-Azar Francis “Frank” Merat Michael Rabinovich (date) June, 30, 2010 * We also certify that written approval has been obtained for any proprietary material contained therein. DEDICATION To my husband who keeps encouraging and helping me to achieve my goals. TABLE OF CONTENTS CASE WESTERN RESERVE UNIVERSITY .................................................. ii SCHOOL OF GRADUATE STUDIES .............................................................. ii DEDICATION ...................................................................................................... iii TABLE OF CONTENTS .................................................................................... iv LIST OF TABLES ............................................................................................. xiv LIST OF FIGURES ................................................................................................ xv ABSTRACT ....................................................................................................... xxii Chapter 1 : I NTRODUCTION .............................................................................. 1 1.1. MOTIVIATION .............................................................................................. 1 1.2. THESIS OVERVIEW ..................................................................................... 4 Chapter 2 : CMOS TECHNOLOGY SCALING AND LIMITATIONS ............ 8 INTRODUCTION .................................................................................................. 8 2.1. SCALING CMOS TECHNOLOGY ............................................................... 8 2.2. TRADITIONAL CMOS SCALING ............................................................... 9 2.2.1. ADVANTAGES OF TRADITIONAL SCALING ................................ 10 2.2.1.1. Transistor Density ........................................................................... 10 2.2.1.2. Performance ..................................................................................... 11 2.2.1.3. Dynamic Power ............................................................................... 12 2.2.2. TRADEOFFS OF TRADITIONAL SCALING ..................................... 15 2.2.2.1. Physical Perspective ........................................................................ 16 2.2.2.2. Device Perspective .......................................................................... 17 2.2.2.3. Circuit Perspective ........................................................................... 25 2.3.NEW TRENDS IN CMOS TECHNOLOGY ................................................. 29 2.3.1.CIRCUIT TECHNIQUES ....................................................................... 30 2.3.1.1. Power Dissipation: Issues & Circuit Techniques ............................ 30 2.3.2. DEVICE OPTIMIZATION TECHNIQUES .......................................... 33 2.4. FUTURE TECHNOLOGY TRENDS USING EMERGING TECHNOLOGIES ................................................................................................ 34 SUMMARY ......................................................................................................... 36 Chapter 3 : MEMS/NEMS BACKGROUND ...................................................... 37 INTRODUCTION ................................................................................................ 37 3.1. MEMS/NEM TECHNOLOGY ..................................................................... 37 3.2. MEMS VERSUS NEMS ............................................................................... 38 3.2.1. CHARACTERSTICS ............................................................................. 38 3.2.2. PHYSICS ................................................................................................ 39 3.2.3. MANUFACTURING ............................................................................. 40 3.2.3.1. TOP DOWN APPROACH (FABRICATED) ................................. 40 3.2.3.2. BOTTOM-UP APPROACH (SYNTHESIZED) ............................. 41 3.3. NEMS STRCTURES .................................................................................... 41 3.4. MEMS/NEMS OPERATION MODES ........................................................ 42 3.4.1. SWITCHING MODE (QUASI-STATIC) .............................................. 43 3.4.1.1. Capacitive Switch ............................................................................ 43 3.4.1.2. Ohmic Contact Switch (Resistive Switch) ...................................... 43 3.4.2. RESONANT MODE (ACOUSTIC) ...................................................... 44 3.5. MEMS/NEMS PHYSICAL ACTUATION PRINCIPLES .......................... 44 3.6. MEMS/ NEMS MATERIALS ...................................................................... 46 3.7. MEMS/NEMS COMPUTATIONS ............................................................... 46 Chapter 4 : LITERATURE REVIEW ................................................................. 48 INTRODUCTION ................................................................................................ 48 4.1. ELECTROSTATIC MECHANICAL SWITCHES ...................................... 48 4.2. ELECTROSTATIC MECHANICAL SWITCHES AS AN EMERGINIG TECHNOLOGY ................................................................................................... 49 4.3. LITERATURE REVIEW .............................................................................. 50 4.3.1. ACTIVE PART‘S MATERIAL ............................................................. 58 4.3.2. FABRICATION APPROACHES .......................................................... 58 4.3.3. VALIDATION/EVALUATION ............................................................ 59 4.3. KEY CRITERIA TO CONSIDER NEMS SWITCHES AS AN EMERGING TECHNOLOGY ................................................................................................... 62 Chapter 5 : ELECTROSTATIC NEMS SWITCHES: CONCEPTS, ANALYSIS, AND DESIGN ................................................................................... 67 INTRODUCTION ................................................................................................ 67 5.1. PRINCIPLE OF OPERATION ..................................................................... 67 5.2. MULTI-PHYSICS DEVICE ......................................................................... 68 5.3. NEMS PHYSICAL QUANTITIES ............................................................... 70 5.4. NEMS PHYSICAL PHENOMENA ............................................................. 70 5.4.1 ELASTIC FORCE ................................................................................... 71 5.4.2. ELECTROSTATIC FORCE .................................................................. 71 5.4.3. INTERMOLECULAR FORCES ........................................................... 72 5.4.4. CONTACT FORCE ............................................................................... 73 5.4.4.1. Elastic Deformation ......................................................................... 74 5.4.4.2. Plastic Deformation ......................................................................... 75 5.4.4.3. Elastic-Plastic Deformation ............................................................. 75 5.4.5. DAMPING FORCE ................................................................................ 76 5.4.5.1. Viscous Damping ............................................................................ 77 5.4.5.2. Compression Damping .................................................................... 78 5.4.6. KINETIC FORCE .................................................................................. 79 5.4.7. CONTACT BOUNCING MOTION PHENOMENA ............................ 79 5.5. NEMS CHARACTERSTICS ........................................................................ 79 5.5.1. PULL-IN AND PULL-OUT VOLTAGES ............................................ 79 5.5.2. SWITCHNIG TIME ............................................................................... 81 5.5.3. ON AND OFF RESISTANCES ................................................................. 82 5. 5.3.1. OFF Resistance ............................................................................... 82 5.5.3.2. ON Resistance ................................................................................. 83 5.5.4. RELIABILITY ISSUES ......................................................................... 85 5.5.4.1. Stiction ............................................................................................. 86 5.5.4.2. Wear ................................................................................................ 88 5.6. NEMS PRODUCTION PROCESS ............................................................... 90 5.7. NEMS SWITCH DESIGN PHASE .............................................................. 92 5.7.1. NEMS SWITCH DESIGN: OBJECTIVE AND DECISION ...............