Reliability Analysis of the Aeroflex ViaLink™ FPGA

1. Reliability Analysis of the Aeroflex ViaLink™ FPGA MAPLD International Conference September 8, 2005 Session D: Reliability Ronald Lake Aeroflex Colorado Springs www.aeroflex.com/radhardFPGA MAPLD2005 / Submission 222

2. Agenda • Background • Aeroflex begins QML-Q / QML-V Qualification of RadHard Eclipse FPGA • Original approach followed MIL-PRF-38535 standards • Approach outlined in previously published papers • Then the world changed (Industry Tiger Team, Aerospace Corp., NASA GSFC, etc.) • New Approach • November 2004: Aeroflex received “Aerospace Requirements for FPGAs in Space” • Aeroflex adopts enhanced MIL-PRF-38535 QML Qualification with Aerospace Corporation guidelines • Un-programmed burn-in • Operating life test (HTOL / LTOL) • Current Status • Aeroflex completes QML-Q / QML-V qualification: August 2005 • Standard Microcircuit Drawing (SMD) #:5962R04229 • Aeroflex announces QML results: September 2005 (MAPLD) • Aeroflex ships first Rad-Assured QML materials: September 2005 MAPLD2005 / Submission 222

3. QML Qualification Compliance Matrix Aeroflex vs. Aerospace Corp. Guidance MAPLD2005 / Submission 222

4. Sample Type/Description Task Completion • Programmed • Un-Programmed • Elemental • Structural 3Q2005 • 1, 3 and 5 pulse programmed ViaLinks (bi-directional) • Uni-Directionally Programmed ViaLink • Unprogrammed ViaLink • Elemental • Structural 4Q2005 Aerospace Evaluation • Structural Evaluation • Using focused ion beam techniques • Output – 3 dimension model (colorized) • Follow-on evaluations • Effect on adjacent ViaLinks • Lot to Lot variation • Via Links vs Programming • Spatial Wafer Evaluation (center to edge) • Lot to Lot variations • Failed ViaLink (if possible) MAPLD2005 / Submission 222

5. Un-programmed ViaLink Cross Section Figure removed until Proprietary issues are resolve. This was a late arriving paper and I apologize for this, I was too nice and will fix that for MAPLD 2006. -- rk MAPLD2005 / Submission 222

6. Reliability Design for ViaLink Operating Life • Goal: Create worst case design for ViaLink stress • Adhere to NASA OLD guidelines for reliability test vehicles for fuse based FPGAs • Design • Use all FPGA logic, memory and I/O resources • Use all wiring types, with associated ViaLinks • Force high fan-out structures for flip flops and logic • Maximize current density through ViaLinks • Manually fix placement to force use of long wires and worst case ViaLinks • Use dedicated and global clocks for synchronous logic • Synchronize reset to insure initialization conditions • Create long combinatorial and synchronous chains for AC delay measurements MAPLD2005 / Submission 222

7. Life Test Environment for RadHard Eclipse • Goal: Subject RadHard Eclipse to real world environment during life test to stress ViaLinks • Life test conditions • Do not de-couple or terminate I/O signals • Allow voltage spikes on inputs • Allow noise on I/O and within wiring array of ViaLinks • Evaluate multiple power sequencing conditions • Use extended times in stress chambers • Closely monitor power supplies MAPLD2005 / Submission 222

8. Test Environment for Characterization • Goal: Create repeatable and accurate test environment for measurement of RadHard Eclipse ViaLink characteristics • Test Conditions • Use Teradyne Tiger tester for accurate measurements of quiescent current and propagation delay • Test all temperature conditions: -55ºC, 25ºC and 125ºC • Test all voltage conditions: 2.3V core and 3.0V I/O; 2.5V core and 3.3V I/O; 2.7V core and 3.6V I/O • Use control units to verify test environment does not change between stress read points • Review all test results prior to next stress, comparing worst case deltas to means MAPLD2005 / Submission 222

9. Un-programmed burn-in • Applied to 100% of un-programmed units passing manufacturing stress • Standard step in Aeroflex QML manufacturing flow • 240 hrs of 125°C burn-in at maximum operating conditions (Vcc=2.7V, Vccio=3.6V) • FPGAs dynamically stimulated during burn-in • After burn-in devices tested for quiescent current (Icc, Iccio) and un-programmed electrical test (3 temperature, min/typ/max voltage) • Percent defective allowable (PDA) <5% MAPLD2005 / Submission 222

10. Operating Life AC Deltas • LTOL: 77 test units + 3 control • No ViaLink failures at 1000 Hrs stress • <3% change in propagation delay • HTOL: 77 test units + 3 control • No ViaLink failures at 1000 Hrs stress • <10% change in propagation delay • Delay deltas calculated for all voltage & temperature combinations MAPLD2005 / Submission 222

11. Co60 AC Deltas • Delta’s calculated at room temperature for all voltage combinations • <5% change in delay at 100 krad(Si) • <15% change in delay at 300 krad(Si) • Irradiated at 1 rad(Si)/sec • Propagation delays stay within simulation limits MAPLD2005 / Submission 222

12. Radiation Testing Single Event Effects Total Ionizing Dose Dose Rate MAPLD2005 / Submission 222

13. Timing Characterization QuickLogic Timing Release Flow • Current Status • Aeroflex speed grade -5 primitive library provides >10% guard band vs. silicon for combinatorial and most synchronous delays • Margins maintained for material after TID of 300krads (Si) • Some exceptions exist due to Aeroflex removal of charge pump on FPGA • Delay library undergoing updates for 4Q2005 release Oscillator Design (34 types) Initial Data Collection Re-Simulate Oscillator Designs Silicon Vs Simulation Spde Release Timing Generation • Pre Release Data • Aeroflex • Aeroflex • QuickLogic • Aeroflex • Aeroflex • QuickLogic Verification Loop MAPLD2005 / Submission 222

14. Summary • Aeroflex Colorado Springs has embraced the Aerospace Corporation’s guidelines to enhance the QML qualification flow • Burn-in analysis demonstrates <3 % defective after 3 temperature testing (QML lot acceptance PDA<5%) • Worst case conditions used for ViaLink™ operating life test • LTOL delay analysis demonstrates <3 % change in propagation delay after 1000 Hrs of stress • HTOL delay analysis demonstrates <10% change in propagation delay after 1000 Hrs of stress • TID delay analysis demonstrates <5% change in propagation delay at 100krad and <12% change at 300krad • ViaLink structural and elemental analysis underway with Aerospace Corporation • RadHard Eclipse FPGA qualified as Rad-Assured QML Q/V MAPLD2005 / Submission 222