On Effective and Efficient In-Field TSV Repair for Stacked 3D ICs

1. On Effective and Efficient In-Field TSV Repair for Stacked 3D ICs Presenter: Li Jiang Li Jiang†, Fangming Ye*, QiangXu† KrishnenduChakrabarty*, and Bill Eklow§ †CUhkREliableComputing Laboratory The Chinese University of Hong Kong *Duke University § Cisco

2. Outline • Introduction • Related Works and Motivation • In-field TSV Repair Framework • Repair Algorithm • Experimental Results • Summary

3. TSV Latent Defects CTE-induced Crack EM-induced Void crack Cooling crack Heating Signal Latency Open Defect [Jung et al., ICCAD’11] [Frank et al., IRPS’11]

4. TSV Repair Schemes: Neighboring Repair Signal-rerouting Signal-Switching [Jiang et al., DATE’12] [Kanget al., JSSC’10] To avoid Aging “hotspot”, we use signal-rerouting as our hardware infrastructure

5. Motivation • Existing repair methods are deterministic • Unaware of timing violating timing requirement after repair • Hard to determine “faulty” TSV:A faulty TSV linking to a particular signal might be a good one if it links to another signal instead • “Faulty” TSV propagation may render the entire TSV grid irreparable • Repair solutions directly affect circuit lifetime reliability

6. Hardware Architecture Periodically On-line test In-field TSV Repair Fail Success Repair Solution Validation Circuit aging can also be detected

7. Repair Algorithm Signal-TSV pair graph: no confirmed timing violation Flow graph: routability checking ST-Graph Flow-Graph Matched ST Pairs Repair Channels Potential ST Pairs Residual Channels Maximal Matching = #Signal Test cost is too high in the runtime Finding the maximal matching

8. Repair Algorithm To reduce test time Tested ST-Pairs Avoid redundant test Previous Matching Current Matching Simultaneously Testing Test ST pairs from next matching in advance Next Matching Routable Not Tested ST-Pairs

9. Spare TSV Sharing How to solve the conflict of using shared spares? Merge STpair-graphs into connected STpair-graph

10. Experimental Setup • Modified Router based Repair Scheme • MF: Continue repair if “new fault” occurs • MF’: Restore repair if “new fault” occurs • Proposed Repair Algorithm • MV: Match with Verified routability • MR: With test time reduction • MS: With spare TSV sharing Comparison Benchmark: IWLS 2005 OpenCore benchmarks data encryption standard (DES) circuit fast-Fourier transform (FFT) circuit • Aging Effect: • Characterized by additional latent delayin TSVs, reflected as resistance increase in terms of time t. • [Frank et.al, IRPS’11], [Ye et al. DAC’12] • Parameters: TSV aging coefficient a, TSV initial resistance R • Following Normal Distribution

11. Results Varied aging coefficients with fixed initial resistance

12. Summary • First work targeting on in-field TSV repair • An efficient TSV repair algorithm that is able to significantly improve MTTF of TSV through the judicious use of spares • Redundancy sharing technique can tolerate aging “hotspots”

13. Thank you for your attention !

14. Results 8x8 TSV grid size repair architecture with varied aging coefficients varied rerouting delay between two adjacent routers (ps)