Lecture 01 Introduction To Mems_new

Introduction to MEMS

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Prof. Tianhong Cui, Mechanical Engineering ME 8254

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Overview

MEMS - evolved from the Microelectronics Revolution

What is micromanufacturing and MEMS? z Why the interest in MEMS? z IC Fabrication Processes z Bulk Micromachining Processes z Surface Micromachining Processes z Combined Processes z References z

IC Industry Timeline 1947

single transistor

1958

first IC

1999

10 million transistors

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So what exactly is MEMS?

MEMS Examples

Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common substrate through the utilization of microfabrication technology or “microtechnology”.

pressure sensors accelerometers flow sensors inkjet printers deformable mirror devices gas sensors micromotors microgears lab-on-a-chip systems

MEMS Timeline

1980

General MEMS Advantages 1999 z

Batch fabrication

z

Reduced size

– Reduced cost

Bulk micromachined pressure sensor

– Is everything better smaller?

Reduced power High precision z New capabilities? z Improved performance? z

2030 TI DMD

(1.3 million micro-mirrors)

?

z

Micromachining Processes

The MicroTechnology/MEMS Tool Set z

Cleanroom plus microfab processes

Standard Integrated Circuit (IC) Processes – Identical to those used in IC fabrication – Generally used for surface micromachining

+

z

Surface Micromachining – Additive processes

z

Bulk Micromachining

z

Dividing line can become very blurry

– Subtractive Process

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Standard IC Processes

Standard IC Processes

Photolithography

Source: Jaeger

Source: CWRU Source: Jaeger

Standard IC Processes

1) Deposit/Grow Thin Films • Sputtering • Evaporation • Thermal Oxidation • CVD • Spinning • Epitaxy

Standard IC Processes 3) Introduce Dopants (to form electrically-active regions for diodes, transistors, etc.) • Thermal Diffusion • Ion Implantation

Standard IC Processes

2) Pattern Thin Films • Lithography • Etching Techniques (wet, dry, RIE)

Micromachining Processes Bulk Micromachining • wet vs dry • isotropic vs anisotropic • subtractive process

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Micromachining Processes Bulk Micromachining

Micromachining Processes Deep Reactive Ion Etching (DRIE)

Source: Madou

• high density ICP plasma • high aspect ratio Si structures • cost: $500K Source: LucasNova

Source: Maluf

Source: Maluf

Source: STS

Micromachining Processes

Source: AMMI

Source: STS

Micromachining Processes

Surface Micromachining

LIGA (lithographie, galvanoformung, abformtechnik)

• additive process • structural & sacrificial layers

• uses x-ray lithography (PMMA), electrodeposition and molding to produce very high aspect ratio (>100) microstructures up to 1000 um tall (1986)

Source: Sandia

Source: Madou

MEMS Examples Micro-structures using LIGA

Source: Kovacs

Micromachining Processes Poor Man’s LIGA • uses optical epoxy negative-resist (SU-8) developed by IBM to produce high aspect ratio micro-structures (1995)

UofL Micro-reaction wells: 150 um wide, 120 um tall, 50 um wall thickness Source: UW

Source: Maluf

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MEMS Examples Pressure Sensor (conventional)

Micromachining Processes

Source: NovaSensor

Wafer-Level Bonding • glass-Si anodic bonding • Si-Si fusion bonding • eutectic bonding • low temp glass bonding

Output Voltage (mV)

60 50 40 30 20 10 0

Source: Maluf

Source: UofL

Source: EV

MEMS Examples Micromotors

0

20

40

60

80

100

120

Pressure (PSI)

MEMS Examples Optical MEMS (MOEMS)

Source: MIT and Berkeley

MEMS Examples Pressure Sensor (ultra-miniature)

Source: NIST, Simon Fraser, UCLA, and MCNC

MEMS Examples Lab-on-a-Chip Systems • separation • dilution • mixing and dispensing • analysis

Source: NovaSensor

Source: Caliper

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Microreactor

SU8 High AR Structures

PZT Cantilever BEAM • Thickness 4.5μm, width 300μm, length 1000μm •15μm under the voltage of 10V • OTS coating to prevent from stiction

Micropump

• Bimetallic Thermal actuation • Three-layer Silicon • The middle layer has 2 check valves • Flowrate 190 μl/min • P 80 mm H2O

MEMS Examples

Integration

Micromachined Tips for FEDs and AFMs

Micromachining processes may be integrated z Both bulk and surface micromachining may be performed on a single substrate z Micromachined structures may be integrated with ICs z

Source: Micron (?)

Source: IBM

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MEMS Examples Neural Probes

MEMS Examples Neural Interface Chip

Source: Stanford

Source: Mich (K. Wise)

MEMS Examples Micro-Grippers

MEMS Examples Micro-Tweezers

Source: Berkeley

Source: MEMS Precision Instruments

MEMS Examples Optical MEMS (MOEMS)

MEMS Examples Accelerometers

Source: IMC (Sweden), Maluf and TI

Sources: Analog Devices, Lucas NovaSensor, and EG&G IC Sensors

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MEMS Examples Channels, Nozzles, Flow Structures, and Load Cells

MEMS References Fundamentals of Microfabrication; Marc J. Madou Micromachined Transducers Sourcebook; G. Kovacs An Introduction to MEMS Engineering; by Nadim Maluf Silicon Micromachining; by Elwenspoek and Jansen Microsensors; by Richard S. Muller, Roger T. Howe, Stephen D. Senturia, R. Smith (Editors) Micromechanics and Mems : Classic and Seminal Papers to 1990; by W. Trimmer (Editor)

Source: EG&G IC Sensors

MEMS WWW Bookstore: http://mems.isi.edu/bookstore/

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