EMC / EMI issues for DSM: new challenges

Transcription

1 EMC / EMI issues for DSM: new challenges A. Boyer, S. Ben Dhia, A. C. Ndoye INSA Toulouse Université de Toulouse / LATTIS, France Long Term Reliability in DSM, 3rd October,

2 Outlines EMC / EMI issues Electromagnetic reliability issues Preliminary studies DSM IC Case Study EMR Characterization Methodology Experimental results Conclusion and prospective Long Term Reliability in DSM, 3rd October,

3 EMC of ICs? Susceptibility to EM waves Emission of EM waves Carbon airplane Equipements Personal entrainments Mobile phone Boards Radar Components Safety systems Control Systems Long Term Reliability in DSM, 3rd October,

4 EMC of ICs? EMC measurement EMC modeling EMC design guidelines EMC model Measurements Long Term Reliability in DSM, 3rd October,

5 Impact of technology scale down More EMC issues More reliability issues Scale down factors Operating frequencies spread Transition time reduction Transient currents increase Power supply reduction Noise margins decrease Delay margins decrease Dissipated power increase gate oxides thinner new materials introduction Consequences Parasitic emission Susceptibility Lifetime R-S07MT : Evaluation de la fiabilité des composants submicroniques, December 2007 Long Term Reliability in DSM, 3rd October,

6 Impact of technology scale down New technology development (DSM, higher integration, SiP, complex architecture) Technological consequences (transient current, voltage margin, higher simultaneous switching noise, ) Multiple constraints (Improve performances and reliability and reduce surface, costs and fabrication delays) Tightened EMC constraints How measuring emission/susceptibility levels? Development of new design solutions? Efficient modeling methods/tools? Long Term Reliability in DSM, 3rd October,

7 Electromagnetic Reliability Electromagnetic Reliability is a new request from electronic equipment suppliers (for automotive, aerospace and consumer) Going further in electromagnetic behavior improvement and at the same time guarantee EMC over the component lifetime. Long Term Reliability in DSM, 3rd October,

8 Electromagnetic Reliability This area is still under-explored and research communities on "IC reliability" and "IC electromagnetic compatibility" have often no overlap. Effects of IC ageing on the EMC levels evolution are still unknown. Could reliability issues of DSM technologies strongly affect EMC of ICs? Spectrum drifts after 10, 15, 30 Years? IC reliability IC EMC db emission Immunity Worst case : immunity margin cancelled Fréquence (MHz) Long Term Reliability in DSM, 3rd October,

9 Electromagnetic Reliability Effect of component ageing on immunity margin Final IC Emission + 10 yrs Amplitude Immunity margin Initial IC Emission Nominal Target Component dispersion margin Safety margin Component aging margin Conception Target 6 db 3 db 6 db Component aging Amplitude Amplitude Nominal Target Conception Target Nominal Target Insufficient margin Frequency Frequency Overrated margin Conception Target Frequency Long Term Reliability in DSM, 3rd October,

10 Preliminary studies Preliminary studies has been conducted on CMOS 0.25 µm ICs to identify an effect of ageing on emission and susceptibility variations Ageing induces a global but small reduction of emission level [Bendhia 08] Strong increase of susceptibility level (up to 10 db!) [Thesis of A. C. Ndoye] Accelerated Accelerated ageing ageing (408h, (408h,-40 c) What about a DSM circuit? Long Term Reliability in DSM, 3rd October,

11 DSM IC Case Study Test chip developed by ST Microelectronics Technology Content I/O power supply Core power supply Packaging CMOS 65 nm Low Power High Vt Bidirectional I/O structures 2.5 V 1.2 V LBGA mm The components have been mounted on a specific EMC board, dedicated to standard conducted and radiated emission and susceptibility tests. Long Term Reliability in DSM, 3rd October,

12 EMR Characterization Methodology Lot of N fresh samples Accelerated or Applicative tests Lot of N aged samples EMC characterization EMC characterization Emission level Evolution of EMC performances? Frequency Long Term Reliability in DSM, 3rd October,

13 EMR Characterization Methodology Accelerated ageing tests are based on AEC-Q100 standard Stress Test Qualification for Integrated Circuits Low Temperature Operating Life (LTOL) High Temperature Operating Life (HTOL) Power Temperature Cycling (PTC) 408h, 40 C for 408 hours Power supply = nominal power + 10% I/O activated 408h, C for 408 hours Power supply = nominal power + 10% I/O activated Cycle -40 c to 80 c Power supply = nominal power + 10% Long Term Reliability in DSM, 3rd October,

14 EMR Characterization Methodology Measurement of conducted emission: 150 ohms method (IEC ) Target frequency : 150 KHz 1 GHz Aim : characterization of conducted noise on power supply Impedance matching network Vdd 120 ohms C dec 6.8 nf 51 ohms Spectrum analyzer Device under test Gnd Long Term Reliability in DSM, 3rd October,

15 EMR Characterization Methodology Measurement of conducted immunity: Direct RF Power Injection (IEC ) Target frequency : 150 KHz 1 GHz Aim : characterization of conducted immunity of power supply and I/O pins Signal synthesizer Nominal signal Amplifier Pforw Prefl Decoupling network Device under test Oscilloscope RF disturbance Directional coupler DPI capacitor Failure detection Long Term Reliability in DSM, 3rd October,

16 EMR Characterization Methodology Reference Part (1 sample 5 times) EMC test set-up Test bench optimization All Parts (20 samples) Part by part : Process variation Lot by Lot (5 samples) Initial EMC Test Applicative or Accelerated Life Test - + EMC test repeatability EMC Testing after Stress - + Emission level or Susceptibility threshold Evidence of EMC drift? Long Term Reliability in DSM, 3rd October,

17 Experimental results For 1 sample Conducted emission variations after LTOL ageing. Emission level tends to decrease after ageing Significant dispersion due to ageing between 1-3 db Non negligible effect of ageing Reduction of emission level Long Term Reliability in DSM, 3rd October,

18 Forward Power [dbm] Experimental results Conducted immunity on input buffer stuck at 0 or 1, before/after LTOL ageing Many dispersions for 0, few dispersions for 1 Immunity level for some samples have dramatically decreased (up to 10 db!) Similar trends compared to previous measurements on a 0.25 µm IC Immunity DPI I/O IN2 to "0" Proto 3 before and after LTOL Small increase of immunity level 5 10M 100M 1G Frequency [Hz] before LTOL after LTOL Standard Deviation (db) Effect of LTOL stress on DPI I/O Immunity IN2 to "0" of Test Chip 65nm Immunity DPI I/O IN2 to "0" Proto 1 before and after LTOL Proto 1 8 Proto 2 25 Proto 3 Proto 4 6 Proto 5 20 Repeatability M 100M 1G Frequency [Hz] Long Term Reliability in DSM, 3rd October, Forward Power [dbm] 10M 100M 1G Frequency [Hz] db! before LTOL after LTOL

19 Experimental results Conducted immunity on power supply pins, before/after LTOL ageing No significant effect of ageing on immunity for injection on power distribution network Smaller core compared to previous 0.25 µm IC case study. What is the contribution of the design? Forward Power [dbm] Immunity DPI Alim Test Chip Proto 1 before and after LTOL Effect of LTOL stress on the DPI ALIM immunity of Test Chip Immunity 65nm DPI Alim Test Chip Proto 4 before and after LTOL 40 Standard Deviation Immunity [db] before LTOL 1 after LTOL 0 Proto 1 Proto 3 Proto 4 Proto 5 Repeatability Forward Power [dbm] before LTOL after LTOL 1M 10M 100M Frequency [Hz] 1M 10M 100M 1M 10M 100M Frequency [Hz] Frequency [Hz] Long Term Reliability in DSM, 3rd October,

20 Conclusion Evolution of CMOS technology will tighten EMC constraints. Reliability of DSM technologies is significantly reduced. New request from electronic equipment suppliers to ensure EMC over all the device life time : Electromagnetic Reliability. Natural ageing of DSM circuits could modify EMC levels. First EMR experiments have been conducted on a 65 nm CMOS circuit. Preliminary studies have shown that : Emission levels are slightly reduced Many dispersions of immunity levels can be observed, depending on the disturbed block. Some alarming reduction of immunity levels can appear. No significant differences on EMC drift for DSM technologies compared to older technologies (to be confirmed on identical designs). Long Term Reliability in DSM, 3rd October,

21 Prospective work: Ageing effect prediction Identify failure and degradation mechanisms which could have an impact on EMC : Which mechanisms (Hot carrier injection, Gate oxide integrity, Electromigration?) Link to transistor fundamental parameters (IDsat, VT, Gm)? Degradation mechanisms model exist but are not adapted to EMC prediction approach: Reliability : statistical, physical, transistor level models EMC : macro models How to introduce aging parameters in standard EMC model? Long Term Reliability in DSM, 3rd October,

22 Prospective work: ICEM model including ageing effect Degradation mechanisms due to accelerated life tests will affect ICEM : current sources (current amplitude decrease), core capacitances (decrease) interconnect resistances (increase) Access resistors Current sources Core capacitances (MOS) Long Term Reliability in DSM, 3rd October,

23 Prospective work: EMR design guidelines Reliability and EMC aware design guidelines exist EMR oriented design? Identify EMC design techniques insensitive to component ageing. New PhD for the specification of a test chip dedicated to : Ageing effects on EMC of basic functional blocks (digital cores, oscillator and PLL, regulator, I/O block) Ageing effects on EMC protections (on-chip decoupling capacitor, differential I/Os, Schmitt trigger, ) Long Term Reliability in DSM, 3rd October,

24 Publications S. Bendhia, M. Ramdani, E. Sicard, Electromagnetic Compatibility of Integrated Circuits, book published by Springer, Dec. 2005, (More information on A. C. Ndoye, S. Bendhia, A. Boyer, L. Guillot, B. Vrignon, «Dérives du Spectre d Emission d un Composant Mixte après Vieillissement Accéléré», CEM08, Paris, Mai 2008 A. Boyer, S. Bendhia, «Fiabilité des Circuits Intégrés face aux Agressions Electromagnétiques», ANADEF 2008, Port d Albret, June 2008 S. Bendhia, A. C. Ndoye, A. Boyer, L. Guillot, B. Vrignon, «IC Emission spectrum drifts after burn-in cycles», Asia Pacific EMC Week 2008, Singapore, May 2008 Long Term Reliability in DSM, 3rd October,

25 Electromagnetic Reliability Aging Effect Long Term Reliability in DSM, 3rd October,