World s First Piezoelectric MEMS Oscillators

Transcription

1 World s First Piezoelectric MEMS Oscillators September 29 th 2012 Harmeet.Bhugra@idt.com Managing Director MEMS Division, IDT Inc Integrated Device Technology, Inc. 1

2 Introduction to 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 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 Sources: CS&A, IDT Silicon $1.2B Frequency Control $4B PAGE 2

3 Frequency Reference (i.e. Heartbeat) for common Applications Performance, Reliability, Cost, Package, Size and Power consumption vary significantly for different applications PAGE 3

4 Today Oscillators are synonymous with Quartz. Frequency selective tank Resonating Tank LC tank Micromechanical resonator Quartz Crystal, SAW Amp Sustaining Amplifier PAGE 4

5 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. What determines the Crystal performance? 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 11 th. Mostly only the 3rd overtone is used. For higher frequencies overtones are more economical. PAGE 5 jx 0 -jx Fundamental mode Spurious responses 3rd overtone Spurious responses 5th overtone Spurious responses Frequency

6 Response MHZ 3555 Resonant Vibration Topographs of a Quartz Plate Primary Mode 0 db. -10 db db. -40 db Frequency, in khz 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 , 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, PAGE 6

7 Ceramic Substrate 7mm Hermetic Package Capacitor Quartz Resonator ASIC PAGE 7 Source: KDS

8 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 PAGE 8

9 PIEZO MEMS TECHNOLOGY PAGE 9

10 Piezoelectric MEMS Resonators ~10 yrs ago Piezoelectric Layer (ZnO/AlN) Aluminum I/O Pad Support Tether Electrodes f L E eff eff L: device s lateral length E eff : effective elastic constant ρ eff : effective mass density Silicon w L t Si Aluminum I/O Pad 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. Georgia Tech Paper - S. Humad et al, IEDM 2003 PAGE 10

11 pmems Technology Capacitive Piezoelectric resonators: need electrode DC bias directly and narrow on piezoelectric actuation gaps. layer. No DC bias. Drive Narrow Signal gap (~100nm) In DC bias Sense Signal Out Bottom electrode AC Signal In Top electrode Piezoelectric Piezoelectric Driving Layer Layer Deformed Charge induced electric on output field Si Body on Si Body Si Si Substrate Bias Layer Force Electrostatic modulated by Electrostatic input Force signal. Si body Force in vibration. Top electrode AC signal Out PAGE 11

12 Typical pmems Resonator Performance S-parameter measurement (106MHz) Q=9525, IL=11.6dB (50W termination) PAGE 12

13 Q IL (db) Q IL (db) Resonator Optimization Tradeoffs between device performance (Q, IL) and size. 100MHz 3rd order device 100MHz 5th order device Width/Length ratio Width/Length ratio PAGE 13

14 pmems TM native high frequency references Native 1GHz Piezoelectric MEMS Oscillator >30dB/dec f 0 ~1.006GHz Q unloaded ~7100 R m ~150Ω 30dB/dec 10dB/dec PN floor Joint Paper by Okhlahoma State Univesity and Georgia Tech, Lavasani et al. at ISSCC 2010 PAGE 14

15 First IDT pmems TM Products Introduced in 2012 IDT pmems TM (Piezoelectric MEMS) resonators for frequency reference applications. Work started in Goal to replace crystal oscillators with pmems TM 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. 6 pin 40+ MEMS patents have been granted and or pending to IDT for pmems TM technology. PAGE 15

16 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 PAGE 16

17 Wafer Level Packaged Resonator Silicon device layer with piezoelectric and electrode layer on top Wafer level packaging (WLP) provides hermetic solution cap cavity Pad Cap Piezo Si Oxide Sub PAGE 17

18 Wafer-Level Distribution Manufacturable in high volumes with 10+ Million WLP resonators analyzed. PAGE 18 18

19 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) PAGE 19

20 MEMS OSCILLATOR DATA PAGE 20

21 pmems TM Oscillator Teardown pmems Die IC Die PAGE 21

22 CrystalFree pmems Oscillators 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 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 Top Frequencies (MHz): * Additional Custom Frequencies Available Upon Request PAGE 22

23 Long Term Frequency Stability 25 C, frequency variations < 2 ppm over 2 years Typical Quartz aging spec: 5 ppm Sample#: 10 Typical Quartz Aging spec.: ±5ppm ±2.5ppm ±0.5ppm Measurement improved Time (months) H. Bhugra et al., Reliability of next generation high performance pmems TM resonator oscillators, Joint Conference of the IEEE International Frequency Control and the European Frequency and Time Forum, PAGE 23

24 Shock and Vibration Tests Passes Military Specs: Vibration: 20G, Shock: 1,500G, Constant acceleration: 30,000G. Passes 70,000G mechanical shock testing. PAGE 24

25 MEMS Oscillator Application Demos Networking Application: SRIO PCIe Bridge (4x5Gbps) MEMS Oscillator: MHz, LVPECL, 7050 Package FPGA Application: Xilinx Virtex 6 MEMS Oscillator: MHz, LVDS, 5032 Package Storage Application: SAS Controller for SSD MEMS Oscillator: MHz, LVPECL, 7050 Package PAGE 25

26 Why do system designers prefer MEMS? Feature Want? MEMS Oscillators Frequency Higher pmems TM 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 PAGE 26

27 Yole 2012 MEMS Forecast MEMS Oscillators just coming out of Development phase into the growth phase PAGE 27

28 Frequency Control TAM CY2012 VCXO $184M 5% TCXO $776M 19% OCXO $166M 4% Ceramic $615M 15% khz XTAL $629M 15% $4.06B Total January 2012 MEMS Oscillators In 2017 XO $446M 11% MHz XTAL $1.2B 31% MEMS Oscillators Today Sources: CS&A, IDT, isuppli PAGE 28

29 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 pmems TM technology offers a compelling solution for high performance oscillators. PAGE 29

30 Thank You Acknowledgements: World Class IDT MEMS Group IDT Sponsored Georgia Institute of Technology lead by Dr. Farrokh Ayazi in Integrated MEMS Laboratory IDT Sponsored Oklahoma State University lead by Dr. Reza Abdolvand in Dynamic μsystems Lab PAGE 30