As Semiconductor Devices Shrink so do their Reliability and - PowerPoint PPT Presentation

As Semiconductor Devices Shrink so do their Reliability and Lifetimes National Software and Airborne Electronic Hardware Standardization Conference August 20-21 Denver, CO Lloyd Condra, Boeing Gary Horan, FAA Bill Scofield, Boeing

Outline • Background As semiconductor devices shrink, so do their reliability and lifetimes • What we have done about it AVSI research results • What we have yet to do Tool development • Implementation

What Does “COTS” Mean? Part Sub-assembly (module) Equipment Modified System Standard Consumer Mil-Aero Industrial Commercial 32 Flavors of COTS (Baskin Robbins only has 31)

Our Challenge …….Design, produce, We develop Our COTS supply certify, and processes, chain is a Complex support methods, and Adaptive System products standards that that evolves using parts allow our according to forces and materials customers beyond our control from Complex to………. Adaptive Systems.

The COTS Semiconductor Industry is a Complex Adaptive System Voltage 500 ‘Incidental’ factors: Scaling • Reliability • Configuration continuity 400 • What aerospace needs Feature size, nm 300 Cu Conductors Driving factors: Low-D k 200 Dielectrics • Cost Model-based • Speed 100 Design • Size • Time-to-market 0 1994 1996 1998 2000 2002 2004 2006 2008 A feature is a line width, gate length, etc. of a CMOS gate.

Semiconductor Wearout 1000 100 Mean Service Mil/Aero lifetimes life, yrs. 10 Computer/cell phone lifetimes 1.0 Technology 0.5 mm 0.25 130 nm 65 nm 35 nm 0.1 mm 1995 2005 2015 Year produced 1.0 μ 0.35 μ Most microcircuits are Service Life (years) 0.18 μ designed for 3-10 year 100 service life 0.1 μ Margin Strong motivation to 10 Typical service life limit insight into long- Source: E. Snyder goal (10 yrs.) term reliability (Sandia), IRPS, 2002) 1990 1995 2000 2005

Predictions Confirmed by Experience* Wearout failures (Hot Carrier Injection) in 90nm ASIC devices • Telecom OEM: 10% failure within 4 years • Process Monitoring OEM: 20% failure within 3 years Major manufacturer of graphic processor units (GPU) limits maximum junction temperature to 80ºC in order to meet 5-year lifetime requirement *Source: DfR Solutions

Predictions Confirmed by Testing AVSI #17 Results 700 FIT 90 nm: ~ 100 - 300 FIT Current state-of-the-art 0.25 μ m: ~20-50 FIT is 45 nm Avionics In- service Data Test system at Tower semiconductor

What We Have Done About Early Semiconductor Wearout • Aerospace Vehicle Systems Institute Project #17 – Participants: Boeing, Honeywell, Goodrich, GE, Rockwell Collins, DoD, FAA, NASA – Time span: 2003-2007 – Subcontractor: Dr. Joseph Bernstein, U of MD • Results – Literature search failure mechanisms, models, parameters – Confirmed models by testing – “Alpha” version of FaRBS software – Avionics system design handbook

Predictions Confirmed by Testing AVSI #17 Results 2010 1.E+03 2005 Acceptable 2000 for Commercial Applications FIT 1.E+02 Required for Avionics 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 Time (equivalent hours) Early Wearout Confirmed!!!

Wearout Mechanisms Electromigration Trench Conducting isolation Gate Gate channel Conducting oxide oxide channel Gate Gate Drain Drain Source Source P+ P+ N+ N+ P-well N-substrate Oxide Hot carrier injection Negative bias Voltage stresses breakdown (HCI) temperature instability (NBTI) γ E − ⋅ TDDB a T D D B V e x p ( ) T D D B g k T E γ − ⋅ a N B T I exp( V ) exp( ) NBTI g N B T I kT γ Current stresses E HCI ⋅ H C D aH C D exp( ) exp ( ) V kT d − ⋅ E EM n a E M J exp( ) kT

FaRBS Reliability Software BQR Reliability User Supplied

90 nm NBTI Degradation Reliability Prediction with FaRBS Reliability vs Time 1.00 Fast β =1 ~0.98 Slow Reliability, R(t)=1-F(t) 0.95 Typ ~2% failure in 0.90 2-4 years 0.85 10 0 5 15 20 Time, (yr) ~3 yrs.

Example FaRBS Outputs Reliability and Failure Rate Estimates 36Mb SRAM 1 0.998 0.996 36 MB SRAM Reliability 0.994 1GB DRAM 0.992 0.99 Board failure rate 0.988 900 0 2 4 6 8 10 12 14 16 18 20 800 Time (years) 700 600 36 MB SRAM 500 FIT 90 nm technology 400 1.2 volts, 70ºC 300 200 100 0 0 2 4 6 8 10 12 14 16 18 20 Time (years)

Example FaRBS Output Board failure rate Board with one 36Mb SRAM and one 1GB DRAM 900 800 700 600 1 FIT = 1 failure/10 9 hrs. 500 FIT 400 300 200 100 0 0 2 4 6 8 10 12 14 16 18 20 Time (years)

Effect of Feature Size β = 4.0 β = 7.3 β = 2.1 β = 1.6 β = 1.3 Source: Wu, E.Y., and R.-P. Vollertson, “On the Weibull Shape Factor of Intrinsic Breakdown of Dielectric Films and Its Accurate Experimental Determination – Part I: Theory, Methodology, Experimental Techniques,” IEEE Transactions on Electronic Devices, vol. 49, no. 12, December 2002. Pp. 2131-2140.

Effect of Voltage on TDDB • 256M DRAM, 78nm CMOS process • Gate oxide thickness approximately 5.5nm • Operating voltage 1.5V. • HTOL at 5.0V/125C • Exponential voltage acceleration with γ = 2.7 1 0 -1 7.75V 7.50V 7.25V 7.00V -2 BetaW=1.32 l ( l (1 F)) -3 -4 10 0 10 1 10 2 10 3 10 4 Time-to-fail (s)

What We Have Yet To Do AVSI Project #71 – “Commercial” version of FaRBS software (DfR Solutions) – Verify software by test data – “Beta test” FaRBS software tool on selected Boeing systems – Update with future technology data, models, and parameters Invite participation by others Provide inputs to aerospace design and reliability documents – DO-254 – MIL-HDBK-217

“Commercial” FaRBS Inputs Make AVSI 17 results “user-friendly” –Graphical user interface (GUI) designed to interact with a wide range of users, e.g., design engineers, reliability engineers, etc. –Requires a minimal set of inputs • Manufacturer • Manufacturer part number • Duty cycle • Use environment (temperature) –Assumptions can be modified by expert users • Operation at rated voltage • Only mfr.-specified thermal solutions (no uprating) • International Technology Roadmap for Semiconductors (ITRS) models and parameters • Applicable to <130nm technology • Default and package failure rates from handbooks (-217, Telcordia) or part manufacturer

“Commercial” FaRBS Outputs Make AVSI 17 results “user-friendly” • Failure rate as a function of time • Results can be exported in a .doc or .xls / .csv format • Expert user will be able to extract failure rates for each failure mechanism • Validation link will provide details on approach and experimental results

Implementation Update System Reliability and Certification Documents System Hardware System FMEA Reliability Functional Prediction Hazard Assessment System MIL-HDBK-217 FTA Hardware Design Assurance System RTCA DO-254 Certification Analysis Software Design Assurance Updates RTCA DO-178B needed