MICHAEL B. COHNMEMS DESIGN & FABRICATION

Application Areas

• MEMS & Packaging• Micro Optics• RF• Biomedical• Telerobotics & Tactile Feedback

Skills• Proposal writing, presentation, fundraising• CAD (Ledit, Solidworks)• FEA / Modeling (Ansys, HFSS, Sonnet, ADS,

SPICE)• Vendor Qualification• Prototype • Manufacturing, SPC• Production facility design & build• Embedded controller• Device physics• Circuits: ultra-low noise (MEMS front-end /

interface)

FEA:Thermal Microactuator

• Ratcheting Actuator

• 10,000g tested

Confidential & Proprietary

FEA: Thermal - Mechanical

FEA: Mechanical Transient• Contact / Impact Force

FEA: Mechanical Transient

Thermal actuator

7 mm

• Three-layer stacked Si / ceramic• Room temperature hermetic seal• Thermal inchworm motors• Self-test & shock monitors• Tested to 10,000 g

Optics & 3D Micro-Assembly• 2 DARPA contracts (CCIT)

• MEMS / IC flip-chip integration• Tip-tilt-piston mirror array• Self-assembling electrostatic comb drive

Wafer-to-Wafer Structure Transfer

• Torsional actuator• SOI layer transfer• Au thermocompression bonding

11

Self Assembling Torsional Actuator

• Fabrication

• Self Assembly

• Actuation

Self Assembling Torsional Actuator

Stator

Pull-down electrode

Aircraft Structural Design -- FEA

• Friction & interface slip• Bolt stress

• Cyclic fatigue

Complex structural analysisSteel tube frame (Aircraft)

MEMS Gyroscope• Mechanical – Electrostatic – Electronic – Mechanical• High-Q MEMS coupled resonators• Ultra-low noise analog front end• MCU mode-lock controller• Carousel stage: “3D printed” (CNC)

Dual Mass Gyroscope

• Stability & mode analysis

• Shock• Noise & sensitivity

analysis• Fabrication (SOI / DRIE)• Vacuum Package• Thermal Design

Dual Mass Gyroscope• SPICE simulation of mechanical

structure• Effect of etch CD on mode separation

MEMS Gyroscope(Single Mass)

MEMS Gyroscope: Future?

• High Q / Mode locked• High amplitude• Angle integrating• Thermal anneal trim

MEMS RF Switch• 2 DARPA Contracts (HERMIT)• “5 Chess Games”:

• RF – Mechanical – Electrostatic – Thermal -- Contacts

• Fabrication & Test• Team Leader / CTO• World Record 30W Power Handling

Structural Simulation (Ansys)

• Mechanical – Electrostatic – Contact

RF Design / Simulation• HFSS, ADS, Sonnet

RF Simulation

RF Testing • 0-20 GHz• VNA, Calibration• RF Packaging

RF Switch Reliability

MEMS Switch Resistance Reliability1e9 cycles, 10mW DC, cold-switched

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.0E+00 2.0E+08 4.0E+08 6.0E+08 8.0E+08 1.0E+09

Cycle #

Res

ista

nce

(o

hm

s)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Std

Dev

Resistance Stdev

• 109 cycles / 10 years• HALT / HAST

RF System Level Design

2-bit section(Al2O3 substrate)

ADS Model

• 4-Bit, 35 GHz Phase Shifter

RF Phase Shifter• Alumina ceramic hybrid• MEMS on ceramic• Flip-chip Au stud bump assembly

Wafer 1 Process

Starting wafer

Contactmesa

Passivation

Adhesion

Dopant

Shorting bar

Etch

Etch

Structure

Undercut

Wafer 2 Process

BondVia

RFPassivation

CPW

ThinWafer

Contact

Etch

Spacer

Seal

LayerStack

Fabricated Devices

RF Switch (SOI / DRIE)

Detail: Electroplating

Electroplating Examples

Ceramic Packaging• Al2O3, AlN, glass, sapphire• Thick / thin film• RF, inertial, biomedical• Hermetic vias & cavities• Low-temp / room temp sealing• CTE mismatch locking• Accelerated testing• Integrated Monitoring• Silicon-ceramic wafer-scale packaging• Designed / build process tools• Flip-chip Au stud bump assembly

Ceramic Packaging• 99.6% Al2O3• Via fill with 4-layer metal• Low temperature hermetic seal• Three-layer die stack

Ceramic Packaging• Hermetic cavity• High aspect gold plating• Thermocompression seal

Ceramic PackagingVacuum package with vias and integrated getter1.8x1.8 mm

Ceramic Packaging

Built Q-switched YAG laser for repair of metal traces

Vacuum Packaging

• Silicon resonator design• Glass interposer• Front-end electronics• Design / build packaging tool• Integrated getters

Vacuum Packaging – Polysilicon Shell

• Polysilicon lid with Au seal ring• Eutectic AuSi seal

Vacuum Packaging – Polysilicon Shell

• Polysilicon lid• Au thermocompression seal• Hermetic vias• Wafer scale package

Vacuum Packaging with Leak Rate Monitor

• mpackages achieved 10-17 atm-cc/sec leak rate

• Monitored using resonator ring-down

Designed / Built Vacuum Packaging Tool

• Experience with high vacuum systems

• High bond force capability allows room temp / low temp sealing

Packaging: Wafer Bonding Process Development

• Nonlinear FEA: • Contact• Friction• Mesh morphing

• Use clamping force to counteract CTE mismatch

• Simulation includes friction, mesh morphing

Designed / Built 1,500 sq ft Clean Room

• Floor plan• Facilities• Environmental• Permits• Tool Install

Biomedical / Robotics

• Laparoscopic / Telesurgery System• Mechanical Design • Software (RTOS)• Preliminary Testing (UCSF / UCB)

Biomedical / Robotics• Full two-handed telerobotic

system• 7 DOF each hand• Master controllers with force

feedback

FEA / Simulation Experience• Ansys

• Static, modal, transient• Structural, thermal,

electrical, • Friction, contact, failure,

nonlinear• FEA + lumped element

(RLC)

• SPICE• Ultra-low noise• MEMS front end

• HFSS,ADS, Sonnet