©2012 Integrated Device Technology, Inc.
World’s First Piezoelectric MEMS Oscillators
1
September 29th 2012
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 3 www.IDT.com
Frequency Reference (i.e. Heartbeat) for common Applications
Performance, Reliability, Cost, Package, Size and Power consumption vary significantly for different applications
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 4 www.IDT.com
Today Oscillators are synonymous with Quartz.
Sustaining Amplifier
Frequency selective tank
LC tank
Micromechanical resonator
Quartz Crystal, SAW
Amp
Resonating
Tank
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 5 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 6 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 7 www.IDT.com
Source: KDS
7mm
ASIC
Quartz
Resonator
Hermetic
Package
Ceramic
Substrate
Capacitor
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 8 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 9 www.IDT.com
PIEZO MEMS TECHNOLOGY
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 10 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 11 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 12 www.IDT.com
Typical pMEMS Resonator Performance
●S-parameter measurement (106MHz)
●Q=9525, IL=11.6dB (50W termination)
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 13 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 14 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 15 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 16 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 17 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 18 www.IDT.com
Wafer-Level Distribution
●Manufacturable in high volumes with 10+ Million WLP resonators analyzed.
18
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 19 www.IDT.com
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)
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 20 www.IDT.com
MEMS OSCILLATOR DATA
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 21 www.IDT.com
pMEMSTM Oscillator Teardown
pMEMS Die IC Die
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 22 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 23 www.IDT.com
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.
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 24 www.IDT.com
Shock and Vibration Tests
●Passes Military Specs: Vibration: 20G, Shock: 1,500G, Constant acceleration: 30,000G.
●Passes 70,000G mechanical shock testing.
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 25 www.IDT.com
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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 26 www.IDT.com
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?
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 27 www.IDT.com
MEMS Oscillators just coming out of Development phase into the growth phase
Yole 2012 MEMS Forecast
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 28 www.IDT.com
$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
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 29 www.IDT.com
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.
BHUGRA – Sep 2012 IEEE COMSOC LECTURE PAGE 30 www.IDT.com
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