How to Identify and Prevent ESD Failures using PathFinder
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This presentation provides an introduction to common ESD failure mechanism in today's ICs and the challenges in addressing them. It will highlight PathFinder, a layout based ESD integrity analysis platform with an integrated modeling, extraction and simulation environment that enables IC designers perform exhaustive verification of all ESD discharge pathways at the IP and full-chip level. It will also share case study of some real life ESD failure scenarios and how PathFinder was used to root-cause them. It reviews the list of ESD checks that can be performed from early floor planning to final sign-off for ESD robustness and ESD failure prevention. Learn more on our website: https://bit.ly/1vRDycB
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How to Identify and Prevent ESD Failures using PathFinder
- 1. 6/23/2014 © 2014 ANSYS, Inc. 1 How to Identify and Prevent ESD Issues Using PathFinder™ Design Automation Conference 2014
- 2. 6/23/2014 © 2014 ANSYS, Inc. 2 Electrostatic Discharge “A transfer of charge between two bodies at different electrostatic potentials, either through contact or via an ionized ambient discharge (a spark).” What is ESD? I/O buffers ESD Clamps ESD Clamps IO Pad I/O pin Drain/Source junction or gate-oxide damage Metal/via melt-down High current event causing latent or catastrophic failures to IC Intended path Unintended path
- 3. 6/23/2014 © 2014 ANSYS, Inc. 3 Human Body/Machine Model(HBM/MM) + + + Charged Device Model(CDM) Discharge currents for different types of ESD events Source: http://www.esda.org/documents/IndustryCouncilWhitePaper2.pdf What is ESD?
- 4. 6/23/2014 © 2014 ANSYS, Inc. 4 PathFinder™: SoC and IP ESD Integrity Layout (DEF/GDS) Technology Spice Netlist/ Clamp Models ESD rules PathFinder gnd vdd vddA gndA gndB vddB
- 5. 6/23/2014 © 2014 ANSYS, Inc. 5 PathFinder™: SoC and IP ESD Integrity Layout (DEF/GDS) Technology Spice Netlist/ Clamp Models ESD rules PathFinder gnd vdd vddA gndA gndB vddB R-Extraction
- 6. 6/23/2014 © 2014 ANSYS, Inc. 6 PathFinder™: SoC and IP ESD Integrity Layout (DEF/GDS) Technology Spice Netlist/ Clamp Models ESD rules PathFinder gnd vdd vddA gndA gndB vddB Isolated bumps Disconnected clamps Missing pin2pin ESD path X Layout Connectivity Checks Layout Connectivity Checks
- 7. 6/23/2014 © 2014 ANSYS, Inc. 7 PathFinder™: SoC and IP ESD Integrity Layout (DEF/GDS) Technology Spice Netlist/ Clamp Models ESD rules PathFinder gnd vdd vddA gndA gndB vddB Resistance Checks R? R? R? R? R? R? Any Point Layout Connectivity Checks Resistance Checks
- 8. 6/23/2014 © 2014 ANSYS, Inc. 8 PathFinder™: SoC and IP ESD Integrity Layout (DEF/GDS) Technology Spice Netlist/ Clamp Models ESD rules PathFinder gnd vdd vddA gndA gndB vddB Isolated bumps Disconnected clamps Missing pin2pin ESD path X LayouRtR eCs-oEisnxtnatenrccateicv Ctitihyoe Cnchksecks R? R? R? R? R? R? Any Point Interconnect Failure Checks Metal/via bottlenecks Current crowding on diode fingers Layout Connectivity Checks Resistance Checks Interconnect Failure Checks
- 9. 6/23/2014 © 2014 ANSYS, Inc. 9 PathFinder™: SoC and IP ESD Integrity Layout (DEF/GDS) Technology Spice Netlist/ Clamp Models ESD rules PathFinder gnd vdd vddA gndA gndB vddB Isolated bumps Disconnected clamps Missing pin2pin ESD path X LayouRtR eCs-oEisnxtnatenrccateicv Ctitihyoe Cnchksecks R? R? R? R? R? R? Any Point Interconnect Failure Checks Metal/via bottlenecks Current crowding on diode fingers Layout Connectivity Checks Resistance Checks Interconnect Failure Checks Dynamic Checks Monitor device stress Dynamic Checks Root-cause Analysis IP/Full-chip Capacity Early Stage to Sign-off
- 10. 6/23/2014 © 2014 ANSYS, Inc. 10 Common ESD Issues in SoCs Device breakdown ESD Device 40% BEOL 30% ESD Network 10% Cross Domain 15% misc 5% ESD Failure Types ESD failures impact first silicon success Interconnect melt-down Cross-domain ESD issues
- 11. 6/23/2014 © 2014 ANSYS, Inc. 11 Inefficient or missing clamps Device Breakdown Source: Cao et al., ESD design challenges and strategies in deeply-scaled integrated circuits, PhD dissertation, Stanford Univ, 2010. ESD Design window from 130 nm to 32 nm technology vss sig D1 D2 vcc Functional devices V>V(break-down) High ESD bus resistance +ve Zap Power2 Ground Zap -ve Zap Why is it more important now? What are the common causes for such failures?
- 12. 6/23/2014 © 2014 ANSYS, Inc. 12 vss sig D1 D2 vcc Functional devices Device Breakdown Signal Bus R checks # Signal bus R check BEGIN_ESD_RULE NAME sigbump2diode_Rcheck TYPE BUMP2CLAMP ARC_R 0.1 TERMINAL_NET_GROUP SIGNAL CLAMP_TYPE1 D1 D2 END_ESD_RULE Power Bus Resistance check #Power Bus R Check BEGIN_ESD_RULE NAME Pwr_Bus_R_check TYPE CLAMP2CLAMP ARC_R 0.1 TERMINAL_NET_GROUP POWER GROUND FROM_CLAMP_TYPE D1 D2 TO_CLAMP_TYPE PWRCLMP END_ESD_RULE Power2Ground R check #Power2Ground R check BEGIN_ESD_RULE NAME PWR2GND_R_check TYPE BUMP2BUMP LOOP_R 5 PARALLEL_R 1 TERMINAL_NET_GROUP POWER GROUND CLAMP_TYPE PWRCLMP SHORT_BUMP_IN_NET_GROUP POWER GROUND END_ESD_RULE How can PathFinder help ?
- 13. 6/23/2014 © 2014 ANSYS, Inc. 13 Positive Zap Negative Zap IO Pad Pad VCC VSS Mx My Mz RD L D1 D2 Clamps Current crowding on ESD device Insufficient via-cuts/ ineffective clamps Insufficient wire width on ESD pathways Interconnect Melt-down Why is it more important now? What are the common causes for such failures?
- 14. 6/23/2014 © 2014 ANSYS, Inc. 14 Interconnect Melt-down # Signal bus CD check BEGIN_ESD_RULE NAME signal_bump2diode_CD_check TYPE CD ZAP_CURRENT 1.3A # ~2kV HBM zap B2C_NET_GROUP SIGNAL SHOTGUN_MODE 1 END_ESD_RULE #Power Bus CD Check BEGIN_ESD_RULE NAME Pwr_Bus_CD_check TYPE CD ZAP_CURRENT 1.3A #~2kV HBM Zap C2C_NET_GROUP POWER GROUND FROM_CLAMP_TYPE D1 D2 TO_CLAMP_TYPE PWRCLMP END_ESD_RULE #Power2Ground CD check BEGIN_ESD_RULE NAME PWR2GND_CD_check TYPE BUMP2BUMP ZAP_CURRENT 1.3A # ~2kV HBM Zap TERMINAL_NET_GROUP POWER GROUND CLAMP_TYPE PWRCLMP SHORT_BUMP_IN_NET_GROUP POWER GROUND END_ESD_RULE IO Pad Pad VCC VSS Define Interconnect CD limits Mx = x mA/um My = y mA/um Mz = z mA/um RDL = r mA/um D1 D2 Power Clamps # Clamp IV Model BEGIN_CLAMP_IV NAME <I-V_clamp_name> Ron <Ron+> [<Ron->] VT1 <VT1+> [<VT1->] VH <VH+> [<VH->] ROFF <Roff+> [<Roff->] END_CLAMP_IV Signal Bus CD checks Power/Ground Bus CD checks Power2Ground CD checks How can PathFinder help ?
- 15. 6/23/2014 © 2014 ANSYS, Inc. 15 Cross-domain ESD Issues High Ground bus R Insufficient/unconnected bridge diodes Unintentional ESD discharge path VSS1 VDD1 Power Clamp VSS2 VDD2 Power Clamp Bridge diodes RVSS Bridge diodes GPIO GPIO GPIO Analog IO GPIO Analog/RF (AVDD) GPU (VDDG) Memory/Cache (VDDM) High Speed I/O CPU CORE (VDDC) Intentional ESD discharge path Why is it more important now? What are the common causes for such failures?
- 16. 6/23/2014 © 2014 ANSYS, Inc. 16 Bus Resistance Checks Clamp connectivity checks VSS1 VDD1 Power Clamp VSS2 VDD2 Power Clamp Bridge diodes RVSS Bridge diodes Cross-domain ESD Issues # Signal bus CD check BEGIN_ESD_RULE NAME VSS_bus_R_Check TYPE C2C FROM_CLAMP_TYPE PWRCLMP TO_CLAMP_TYPE B2B_DIODE ARC_R 0.5 END_ESD_RULE #Cross-domain CD Check BEGIN_ESD_RULE NAME Cross_domain_CD_Check TYPE CD ZAP_CURRENT 1.3A #~2kV HBM Zap NET_PAIR VDD1 VSS2 END_ESD_RULE How can PathFinder help ? # Clamp connectivity Checks in PathFinder TCL> perform clampcheck # pin2pin connectivity –allNetConn # report disconnected net pairs -rptDisconn Cross-domain CD checks
- 17. 6/23/2014 © 2014 ANSYS, Inc. 17 PathFinder Core Technologies & Benefits Capacity Full-chip capacity with package impact Accuracy ESD snap-back device modeling Current crowding on diode fingers IV curve support Usability Rich GUI for debug and optimization Root-cause the bottleneck in ESD bus
- 18. 6/23/2014 © 2014 ANSYS, Inc. 18 ESD-aware SoC Design Flow Analysis driven clamp placement vdd gnd ESD Clamp ESD Clamp ESD Clamp X IO ring ESD bus planning Floor plan Resistance and current density limit sign-off GPIO GPIO GPIO Analog IO GPIO Analog/ RF (AVDD) GPU (VDDG) Memory/Cache (VDDM) High Speed I/O CPU CORE (VDDC) Final sign-off IO Ring IP level IO Pad level
- 19. 6/23/2014 © 2014 ANSYS, Inc. 19 Summary • Full chip-level ESD integrity analysis solution • PathFinder coverage: – Layout connectivity checks – Resistance checks – Interconnect failure checks – Dynamic CDM checks for IPs • Part of ESDA reference flow and TSMC reference flow