Picosecond Laser Stimulation status, applications & challenges

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1 Picosecond Laser Stimulation status, applications & challenges Vincent POUGET IMS, University of Bordeaux, Talence, France Laboratoire de l Intégration, du Matériau au Système CNRS UMR 5218

2 Outline Picosecond laser stimulation Principles of laser stimulation Specifics of pulsed laser stimulation Energy vs power Charge collection dynamics Impact on resolution Applications Results PULS, TRLS, Fault injection Implementation Challenges Conclusions 2

3 Introduction Laser-based optical techniques Stimulation / Analysis Electrical Optical Static Dynamic Static OBIC, OBIRCH, LIVA, TIVA, SEI Lock-in OBIRCH, Pulsed-OBIC, PULS Dynamic SDL, LADA SEET, LVP, TRLS 3

4 Optoelectronic effects Local energy transfer Photon absorption C V Heat Electron energy increases Electrical barrier C V P N Current C Charge Material barrier V Si SiO 2 Si Higher photon energy needed 4

5 Different laser-induced faults Parametric fault Logical fault Degradation Mode Electrical modelling Laser Power Photoelectrical - Photocurrent - Commutation time - Supply current - Timing error - Transient -Bit flip - Latchup - Breakdown - Fusion Photothermal - Resistivity - Leakage current - Commutation time - Propagation time - Supply current - Timing error - Transient -Bit flip - Fusion 5

6 Pulsed laser specifics Short pulse Time resolution Wide spectrum High peak power High intensity when focused Nonlinear effects Risk of degradation Optical integration constraints Optical power Peak power 0 Energy: Limited energy Negligible heating τ Time Laser source technology 6

7 Influence of laser pulse duration 1E-5 1E-6 Energy Device simulation Linear model 10 Threshold pulse energy for flipping a logical state Energy (J) 1E-7 1E-8 1E-9 1E-10 Power Device simulation Linear model 1 0,1 0,01 Power (W) Threshold peak power for flipping a logical state 1E-11 1E-12 1E-3 1E-13 1E-12 1E-11 1E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 Pulse Duration (s) E ( ) Eγ qs 2iLτ = S et + α α 1 e 1 e th τ d d L 7

8 Influence of laser pulse duration Laser pulse 1ps - 2.5pJ Laser pulse 1ns - 10pJ A. DOUIN, PhD thesis,

9 Charge collection mechanisms in Pulsed OBIC Intensity CW-Nanosecond pulse Intensity Picosecond pulse Laser pulse t (ns) Photocurrent at transistor level t (ps) Drift Diffusion Charge collection volumes 9

10 TCAD simulation of resolution improvement Scanning through two transistors Transient amplitude (a.u) Laser position (µm) 10

11 Applications Failure analysis Defect localisation (current paths, timing errors ) Design debug by transient parametric or logical fault injection Latchup & latent defect localization Radiation effects testing Single-event effects Technology evaluation & qualification Parts screening Reverse engineering Security evaluation Fault injection Functionnal analysis 11

12 Methodology PULS Technique Static electrical stimulation Imaging of the transient response on an output or on the supply current Y t TRLS Technique Dynamic electrical stimulation Synchronization between Test Pattern and Laser Pulse Measurement of the laser induced transient on the output for different delays τ Y t X τ X 12

13 PULS Results Scanning of an inverter chain Imaging of output signal amplitude in grey scale Visualization of the propagation of the laser-induced glitch Later sampling times = upstream the chain 13

14 TRLS Results Input Input Laser Output Time Output Peak to Peak (V) Input Output τ =2ns τ =6ns τ =10ns 14

15 Time-resolved laser fault injection 15

16 Errors Mappings in an SRAM-based FPGA 9mm 510µm BRAM CLB LUT 26µm 7,5µm 195µm 21µm 3,4µm 226µm Static testing: configuration errors analysis Dynamic testing: application analysis Other Resources 40,5µm 30,5µm 16

17 ATLAS Laser Facilities at IMS NIR-tunable Picosecond laser source Amplified Femtosecond parametric laser source Computer controlled tunability : nm Energy : up to 1 mj Picosecond synchronization of laser pulse with test vector 5 laser-injected microscopes Backside testing Microprobing station with backside laser scanning microscope Dedicated test chips Fully automated ATLAS-i : compact version dedicated to radiation testing services 17

PULSCAN Created in 2008, laureate of 2008 French trophy for

and systems for IC testing & FA Custom optical design and

debug & qualification Custom electronic testbeds for

18 PULSCAN Created in 2008, laureate of 2008 French trophy for innovating technology company creation Pulsed laser modules and systems for IC testing & FA Custom optical design and integration services Compact digital test systems for design debug & qualification Custom electronic testbeds for at-speed and remote testing Laser testing services on ATLAS & ATLAS-i 18

and degradation thresholds Laser-ATE synchronization Jitter as low as 20ps can be achieved but simpler electrical

19 Challenges Resolution Improved, but still a laser technique Transient signal observability Rely on DUT as the detector Latchup sensitivity Backside pulsed OBIC can easily trigger parasitic structures Laser energy Working between signal and degradation thresholds Laser-ATE synchronization Jitter as low as 20ps can be achieved but simpler electrical set-up needed. Methodology One more dimension to consider ( pulse-clock delay) More information can be extracted at each pixel 19

20 Conclusions Picosecond laser stimulation Improved time resolution & at speed testing Spatial resolution improvement (to be quantified) Several applications of interest for FA labs customers First industrial prototype in 2009 Silicon for case studies welcome Work in progress on the next step in pulsed laser approaches: femtosecond techniques (TPA, EFISH ) 20

Laser tests of Wide Band Gap power devices. Using Two photon absorption process

Laser tests of Wide Band Gap power devices Using Two photon absorption process Frederic Darracq Associate professor IMS, CNRS UMR5218, Université Bordeaux, 33405 Talence, France 1 Outline Two-Photon absorption