A Mixed-Signal/MEMS CMOS Co-Design Flow with MEMS-IP Publishing / Integration

1. A Mixed-Signal/MEMS CMOS Co-Design Flow with MEMS-IP Publishing / Integration Che-Sheng Chen1 (jason@nctutwt.net), Louis Thiam2, Ahmed Hussein Osman2, Kuei-Ann Wen1, Long-Sheng Fan3 1 Inst. Of Electronics, National Chiao Tung University, Taiwan 2 VCAD, Cadence Design System, Ltd, USA 3 Inst. Of NanoEngineering and MicroSystems, National Tsing Hua Unversity, Taiwan

2. Single monolithic CMOS-MEMS Analog+Mixed-Signal + Digital Components MEMS IP Signal Proc C-to-V C-to-V MEMS Inter-digitized Sensor Glue Logic Clock Tree & Divider ADC Inter-digitized Sensor IP Motivation FEM Simulation Design Team Fragmentation Cross-domain Verification MEMS + Mixed-Signal + Digital concurrent design Integration Cross-discipline Verification Methods for efficient use of EDA + FEM

3. Outlines • MS/MEMS Co-Design Flow Overview • MEMS Design Sub-flow • MEMS HDL Behavioral Modeling • DRC-aware Layout Generation • MEMS-IP Publishing/Integration Interface (SIMPLI) • Overview • Layout Black-boxing • HDL Code Encryption • Electrical Parasitic Extraction • Mixed-Signal Design Sub-flow • Correlated Double Sampling Capacitive Readout • Summary

4. MS/MEMS Co-design FlowIP Integration Approach • MEMS design flow is traditionally top-down starting from mechanical characteristics with FEM iterations • SIPP-SIMPLI interface is providing the bridge between MEMS and IC designers • IC design flow integrate MEMS components as IP

5. Outlines • MS/MEMS Co-Design Flow Overview • MEMS Design Sub-flow • MEMS HDL Behavioral Modeling • Specification-Driven Verification • DRC-aware Layout Generation • MEMS-IP Publishing/Integration Interface (SIMPLI) • Overview • Database Structure • Code/Layout Encryption • Electrical Parasitic Extraction • Mixed-Signal Design Sub-flow • Correlated Double Sampling Capacitive Readout • Summary

6. MEMS Design Sub-flowTop-down approach

7. MEMS Design Sub-flow DetailsInterleaved Interaction

8. MEMS HDL Macro-Modeling (1)Interfacing multi-physics, electrical and MEMS geometries • Advantages of HDL behavioral modelling for MEMS: • Multi-disciplinary language combining physics and electrical quantities • Open standard to enable re-use and flexible mixed-signal simulation environment • Ability to create highly parameterizable component libraries • MEMS geometrical structure description can be part of the macro-model • Natural convergence toward mixed-signal and digital verification

9. MEMS HDL Macro-Modeling (2)Describing multi-physics equivalence with electrical • Each physical equations can be stated independently and HDL concurrent process statement enables system solution convergence • No limit to describe 2nd, 3rd order effects but at expense of development time • Models can be further enhanced based on results extracted from FEM simulation

10. MEMS Functional Verification cockpitSpecification-driven verification

11. MEMS Functional ValidationRe-usable and scalable verification environment • Single specification-driven environment for: • Re-use and automation of verification tasks • Synthetic view of design status versus specification target • Testing environment can be hierarchical • Use model similar to digital functional verification

12. MEMS Physical DesignDRC aware parameterizable layout generator Spring Beams Width Finger Width Finger Length Eatch Hole Separation Length Initial Displacement Eatch Hole Width Length Electrode-to-Mass Separation Length • SKILL based PCell enables parameterization over geometrical parameters with DRC awareness • Parameterization linked directly to HDL macro-modelling in order to enabled schematic-driven layout

13. Outlines • MS/MEMS Co-Design Flow Overview • MEMS Design Sub-flow • MEMS HDL Behavioral Modeling • Specification-Driven Verification • DRC-aware Layout Generation • MEMS-IP Publishing/Integration Interface (SIMPLI) • Overview • Database Structure • Code/Layout Encryption • Electrical Parasitic Extraction • Mixed-Signal Design Sub-flow • Correlated Double Sampling Capacitive Readout • Summary

14. SIPP-SIMPLI Subflow conceptIP publishing and integration

15. SIPP-SIMPLI MEMS IP Publishing SubflowAutomated approach • SIPP-SIMPLI operated on standard inputs and generates views required for Mixed-Signal design within Cadence environment • SIPP-SIMPLI requires following Cadence tools: • AMS Incisive for processing HDL models • Abstract Generator for black-box layout generation • Assura for MEMS DRC compliance • QRC for MEMS parasitics extraction

16. SIPP-SIMPLI MEMS IP Integration SubflowAutomated approach • Only Virtuoso views have to be re-created in target PDK which might be packaged differently between MEMS IP provider and end-user • If PDK package identical between MEMS IP provider and IC designer then MEMS IP published by SIPP-SIMPLI can be re-used as-is

17. SIPP-SIMPLI Virtuoso Custom InterfaceSingle interface for publishing and integration • Single interface and options for both publishing and integration • Interface integrated directly with Virtuoso platform and compatible with both IC 5.1.41 and IC 6.1.3 • Support batch processing through SKILL APIs for entire library management and maintenance

18. SIPP-SIMPLI Layout ProcessingLayout black-boxing while enabling accurate integration

19. SIPP-SIMPLI Functional ProcessingHDL description encrypted while enabling accurate simulation

20. SIPP-SIMPLI Extraction ProcessingLayout extraction while enabling accurate parasitics

21. Outlines • MS/MEMS Co-Design Flow Overview • MEMS Design Sub-flow • Overview • MEMS HDL Behavioral Modeling • Specification-Driven Verification • DRC-aware Layout Generation • MEMS-IP Publishing/Integration Interface (SIMPLI) • Overview • Database Structure • Code/Layout Encryption • Electrical Parasitic Extraction • Mixed-Signal Design Sub-flow • Overview • Correlated Double Sampling Capacitive Readout • Design Summary • Conclusion

22. CMOS Mixed-Signal MEMS Subflow conceptMeet-in-the-middle approach

23. CMOS Mixed-Signal MEMS Subflow detailsMeet-in-the-middle approach

24. Correlated Double Sampling Readout • CDS circuit is suitable for capacitive sensor readout • Offset cancellation & Low frequency noise reduction • Suitable for following Analog to Digital conversion • Following another S/H amplifier for proper sensitivity • Process: UMC CMOS-RF 180nm

25. Schematic Capture of Monolithic Integration

26. Schematic-Driven Layout AssemblyHierarchical layout while reducing LVS errors • Schematic-driven layout enables to track connectivity between schematic and layout view • SIPP-SIMPLI creates a connectivity aware view for safe layout integration • Custom router could be leveraged since MEMS black-box as connectivity and antenna information • SIPP-SIMPLI has also LEF file for digital P&R integration

27. Design Summary

28. The first result of accelerometer (ACC) fabricated with .18mm 8” CMOS foundry under the constrain of standard CMOS process. [1] SEM of the ACC [2] Movement of the fingers triggered by external voltage source [3] Capacitance variation under the excitation of shaker with 20~8kHz shaking. ( The green one is the "PZT reference accelerometer“ provided as the reference and the blue one is the performance of DUT.)

29. Outlines • MS/MEMS Co-Design Flow Overview • MEMS Design Sub-flow • Overview • MEMS HDL Behavioral Modeling • Specification-Driven Verification • DRC-aware Layout Generation • MEMS-IP Publishing/Integration Interface (SIMPLI) • Overview • Data Structure • Code/Layout Encryption • Electrical Parasitic Extraction • Mixed-Signal Design Sub-flow • Overview • Correlated Double Sampling Capacitive Readout • Design Summary • Conclusion

30. Conclusion • A Mixed Signal-MEMS co-design flow is proposed for CMOS/MEMS monolithic integration. • A MEMS IP Publishing/Integration interface is developed to enable handshaking between MEMS & Mixed signal circuits. • With parametric layout & HDL, MEMS/CMOS co-optimization can be achieved. • A fully integrated CMOS monolithic accelerometer has been implemented to demonstrate the proposed design flow.

31. Q & A