World’s First Piezoelectric MEMS Oscillators · MEMS is taking advantage of silicon level...

©2012 Integrated Device Technology, Inc.

World’s First Piezoelectric MEMS Oscillators

1

September 29th 2012

[email protected]

Managing Director

MEMS Division, IDT Inc.

BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 2 www.IDT.com

Introduction to IDT

IDT is the #1 silicon Timing supplier in the $1.2 B silicon timing market.

Innovation:

Over 4,000 unique timing devices

Best Performance Silicon Timing

Understanding:

Foremost experts in Silicon timing technology

Unparallel Service and support:

Fast-turn model for custom timing devices

World class applications engineers

Frequency Control

$4B

Silicon

$1.2B

Sources: CS&A, IDT

Overview: Founded: 1980; NASDAQ: IDTI; Workforce: 2000

Employees; Headquarter: San Jose, CA; FY11 Revenue:

$625M, R&D Spending: $150M/yr

Core Expertise: World Leader in Timing, Serial Switching and

Interfaces


Frequency Reference (i.e. Heartbeat) for common Applications

Performance, Reliability, Cost, Package, Size and Power consumption vary significantly for different applications


Today Oscillators are synonymous with Quartz.

Sustaining Amplifier

Frequency selective tank

LC tank

Micromechanical resonator

Quartz Crystal, SAW

Amp

Resonating

Tank


What determines the Crystal performance?

● The angle and axis of cut determines the performance and characteristics.

● The rate of vibration (frequency), is determined by the cut, size, and shape of the resonator.

● Crystals have many different modes of vibration. (fundamental, harmonic, overtone, etc)

● Thickness of quartz plate determines frequency of vibration.

● Thinner plate = Higher frequency

● Oscillations at odd multiples of the fundamental mode, which include the 3rd, 5th, 7th, 9th, and 11th.

● Mostly only the 3rd overtone is used. ● For higher frequencies overtones are

more economical.

0

jX

-jX Fundamental mode

3rd overtone

5th overtone

Frequency

Spurious responses

Spurious responses

Spurious responses


3200 3400 3600 3800

0 db.

-10 db.

-20

-30 db.

-40 db.

Frequency, in kHz

Resp

onse

3200

MH

Z

3256

3383

3507

3555

3642

3652

3707

3742

3802

3852

Resonant Vibration Topographs of a Quartz Plate

W. Shockley, D. R. Curran & D. J. Koneval, “Energy Trapping and Related Studies of Multiple Electrode Filter Crystals,” Proc. 17th Ann. Symp. On Frequency Control, pp. 88-124, 1963. W. J. Spencer, "Observation of Resonant Vibrations and Defect Structure in Single Crystals by X-ray Diffraction Topography," in Physical Acoustics, Vol. V, W. P. Mason and R. N. Thurston, Eds., Academic Press, New York, 1968.

Primary Mode


Source: KDS

7mm

ASIC

Quartz

Resonator

Hermetic

Package

Ceramic

Substrate

Capacitor


Quartz Issues

Quartz references have a number of issues:

Requires hermetically sealed packages

Difficult to achieve >50MHz without using over-tones & degrading reliability

Doesn’t remain stable under vibration & shatters with shock

Limited number of suppliers grow bulk quartz material and develop ceramic packages

Presence of activity Dips

Failure rates (zero time failure) vary from as high as hundreds of ppm to as low as 10ppm for quartz oscillators


PIEZO MEMS TECHNOLOGY


Electrodes Piezoelectric Layer (ZnO/AlN)

Aluminum I/O Pad

Aluminum I/O Pad

L

w

tSi

Support Tether

Silicon

pMEMS™ resonator Single crystal silicon (SCS) with piezoelectric layer (e.g., AlN) on top. Piezoelectric transduction on Silicon.

Frequency determined by material’s acoustic velocity and device dimension L.

No DC voltage required, Low motional resistance and large power handling.

Piezoelectric MEMS Resonators ~10 yrs ago

eff

effE

Lf

2

10

L: device’s lateral length Eeff: effective elastic constant ρeff: effective mass density

Georgia Tech Paper - S. Humad et al, IEDM 2003


pMEMS Technology

● Capacitive resonators: need DC bias and narrow actuation gaps.

Si Body Si Body on Bias

Electrostatic Force

Electrostatic Force

Force modulated by input signal. Si body in vibration.

Si Body Si Body on Bias

DC bias Narrow gap (~100nm)

AC Signal In

AC signal Out

● Piezoelectric resonators: electrode directly on piezoelectric layer. No DC bias.

Si Substrate Layer

Top electrode Top electrode

Bottom electrode

Driving electric field Piezoelectric Layer

Si Substrate Layer

Piezoelectric Layer Deformed Charge induced on output

+ + + + + + + + + + + +

Drive Signal In

Sense Signal Out


Typical pMEMS Resonator Performance

●S-parameter measurement (106MHz)

●Q=9525, IL=11.6dB (50W termination)


Resonator Optimization

●Tradeoffs between device performance (Q, IL) and size.

0

2

4

6

8

10

12

14

16

18

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

IL (

dB

)

Q

Width/Length ratio

100MHz 3rd order device

0

2

4

6

8

10

12

14

16

18

3000

4000

5000

6000

7000

8000

9000

10000

11000

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

IL (

dB

)

Q

Width/Length ratio

100MHz 5th order device


Native 1GHz Piezoelectric MEMS Oscillator

>30dB/dec

30dB/dec

10dB/dec PN floor

f0~1.006GHz Qunloaded~7100

Rm~150Ω

pMEMSTM native high frequency references

Joint Paper by Okhlahoma State Univesity and Georgia Tech, Lavasani et al. at ISSCC 2010


First IDT pMEMSTM Products Introduced in 2012

IDT pMEMSTM (Piezoelectric MEMS) resonators for frequency reference applications. Work started in 2007.

Goal to replace crystal oscillators with pMEMSTM based oscillators that: Have comparable or better performance than XOs.

Have higher native Frequencies with good phase jitter.

Smaller packaging.

Better Reliability - Highly shock and vibration resistant.

Cost effective.

40+ MEMS patents have been granted and or pending to IDT for pMEMSTM technology.

6 pin


Wafer Level Packaged pMEMS Resonators

●Why is Wafer Level Packaging (WLP) important? ● All resonators are subject to environmental factors such as Moisture, mechanical

stress, contamination etc. ● The idea is to micro-encapsulate the resonator at wafer level using

semiconductor processes. ● Eliminate quality/reliability issues faced during crystal oscillator

assembly process. ● WLP is specific to the type of resonator that needs to be encapsulated i.e. is

custom designed. It has a direct impact on the die size ->> Cost for MEMS die

● Benefit: Easier to package in a plastic package since this is like package inside a package


Wafer Level Packaged Resonator

● Silicon device layer with piezoelectric and electrode layer on top

● Wafer level packaging (WLP) provides hermetic solution

Sub Oxide

Si Piezo

Pad Cap

cap

cavity


Wafer-Level Distribution

●Manufacturable in high volumes with 10+ Million WLP resonators analyzed.

18


IDT pMEMS

Technology

• World’s smallest WLP resonator (better reliability and cost)

• No power source needed (passive i.e. mimics quartz)

• Higher native frequency (up to ~1GHz)

• Lower Insertion Loss (IL ~10dB) – Better Noise performance

• Reliable Manufacturing (no ~100nm electrode gaps)

• No Stiction issues (cause reliability failures)


MEMS OSCILLATOR DATA


pMEMSTM Oscillator Teardown

pMEMS Die IC Die


BENEFITS / FEATURES

●Get any frequency you want (50 MHz to 625MHz).

● Factory programmed, No

external Crystal needed.

●Short lead times: Semiconductor level availability

●Better Reliability: No Zero Time Failures, No activity

dips, Better shock and Vibration

resistance

●Save money compared to high performance XO’s.

●Standard footprint compatible packages (multiple sources).

LVDS / LVPECL

5032

7050

Package Size 5.0 x 3.2 mm 7.0 x 5.0 mm

Supply Voltage 2.5 or 3.3V 2.5 or 3.3V

Frequency Range 50 MHz ~ 625 MHz 50 MHz ~ 625 MHz

Frequency Stability ± 50 ppm ± 50 ppm

Temperature Range -40 to +85°C -40 to +85°C

125 133.33 148.5 150 155.52 156.25

159.375 161.133 187.5 200 212.5 250

* Additional Custom Frequencies Available Upon Request

Top Frequencies (MHz):

CrystalFree™ pMEMS Oscillators


Long Term Frequency Stability

Typical Quartz Aging spec.: ±5ppm

Sample#: 10

±0.5ppm

Measurement improved

±2.5ppm

25°C, frequency variations <2 ppm over 2 years

Typical Quartz aging spec: 5 ppm

Time (months) H. Bhugra et al., “Reliability of next generation high performance pMEMSTM resonator oscillators,” Joint Conference of the IEEE International Frequency Control and the European Frequency and Time Forum, 2011.


Shock and Vibration Tests

●Passes Military Specs: Vibration: 20G, Shock: 1,500G, Constant acceleration: 30,000G.

●Passes 70,000G mechanical shock testing.


MEMS Oscillator Application Demos

Networking Application: SRIO PCIe Bridge (4x5Gbps)

● MEMS Oscillator: 156.250 MHz, LVPECL, 7050 Package

FPGA Application: Xilinx Virtex 6 ● MEMS Oscillator:

200.000 MHz, LVDS, 5032 Package

Storage Application: SAS Controller for SSD ● MEMS Oscillator:

150.000 MHz, LVPECL, 7050 Package


Feature Want? MEMS Oscillators

Frequency Higher pMEMSTM resonators can cost effectively provide higher native frequencies that enable lower jitter (sub-ps).

Size Smaller MEMS enables sizes smaller that traditional XOs

Stability Long Term and Short Term

Better MEMS demonstrates either comparable or better stability

Functions More Configurable PLL, multipliers, dividers, programmable, multiple Outputs

Power Supply Lower LVPECL, LVDS, 3.3V, 2.5V and lower…

Activity Dip Absence None

Lead Times Short Very short lead times, Immediate sampling

Inventory Small No Shortages Semiconductor Level Availability

Reliability Better Higher Reliability Silicon Level Reliability, Production Cost Savings

Cost Lower Lower costs due to semiconductor scaling and plastic packages

Operating Temperature ranges Wider Wide temperature ranges commercial/industrial

Why do system designers prefer MEMS?


MEMS Oscillators just coming out of Development phase into the growth phase

Yole 2012 MEMS Forecast


$4.06B Total January 2012

Frequency Control TAM CY2012

OCXO

$166M

4% TCXO

$776M

19%

Ceramic

$615M

15%

kHz XTAL

$629M

15%

XO

$446M

11%

VCXO

$184M | 5%

MHz XTAL

$1.2B

31%

Sources: CS&A, IDT, iSuppli

MEMS Oscillators Today

MEMS Oscillators In 2017


Summary

● Quartz Frequency References have been around for decades

Technology Disruption is underway MEMS is taking advantage of silicon level reliability, manufacturability and

miniaturization to push frequency references into a new era.

pMEMS oscillators demonstrate improved reliability over existing solutions (semiconductor WLP reliability and vibration resistance). Excellent long term stability

Barriers to entry are high for MEMS products ● Look at the whole picture (MEMS + IC + Packaging + Final Test + Form Factor). MEMS

die drives product differentiation but is only 30% of the overall effort. ● Actively manage Performance/Cost tradeoffs without giving up on Quality and Reliability

● MEMS adoption for frequency reference applications is increasing. ● Today MEMS frequency reference solutions offered only by small startups with some

technical and commercial barriers yet to be overcome.

● There has been customer reluctance in adopting new technologies. Established timing companies such as IDT are helping bringing these technologies to market.

The future for MEMS frequency references is bright…

…. and pMEMSTM technology offers a compelling solution for high performance oscillators.


Thank You

Acknowledgements: World Class Team @ IDT MEMS Group IDT Sponsored Research @ Georgia Institute of Technology lead by Dr. Farrokh Ayazi in Integrated MEMS Laboratory IDT Sponsored Research @ Oklahoma State University lead by Dr. Reza Abdolvand in Dynamic μSystems Lab

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