High Performance Interconnect and Packaging Chung-Kuan Cheng CSE Department UC San Diego

Research Scope Scalable System: Power, Delay, Cost, Reliability Interconnect-Driven Designs Wire Planning: Non-Manhattan Interconnect Networks: Topology, Physical Layout Clock & Power: Shunts + Trees (3) Interconnect Style: Surfliner (2) Datapath: Shifters, Adders, Mul. Div. Packaging: Pin Breakaway (1) Simulation Static Timing Analysis: Hierarchy, Incremental SPICE: Whole System Analysis

1. Pin Breakaway Interfaces of Chip and Package, Package and Board. Breakaway of Array of Pins Patterns of Breakaway Obj: Cost= # Breakaway Layers

1. Pin Breakaway Row by Row Escape: Escape interconnect row by row from outside toward inside.

1. Pin Breakaway (Cont.) Parallel Triangular Escape: This method divides the objects into groups and escape each group with a triangular outline.

1. Pin Breakaway (Cont.) Central Triangular Escape: Escape objects from the center of the outside row and expands the indent with a single triangular outline.

1. Pin Breakaway (Cont.) Two-Sided Escape: Escape objects from the inside as well as from the outside. The outline shrinks slowly and also follow zigzag shape.

1. Pin Breakaway (Cont.) The movement of area array contour Row by Row Parallel Triangles Central Triangle Two-Sided

1. Pin Breakaway: Design Rules Parameters used: the pad pitch = 150  m the pad diameter = 75  m the line width = 20  m the spacing = 20  m

1. Pin Breakaway: Results LayerRow by row Parallel triangular Central triangular Two sided x 40

1. Pin Breakaway: Results LayerRow by row Parallel triangular Central triangular Two sided x 20

2. Interconnect Style: Surfliner Global Interconnect trend Scalability

2. Surfliner - Features Speed of light < 1/5 Delay of Traditional Wires Low Power Consumption < 1/5 Power Consumption Robust against process variations Short Latency Insensitive to Feature Size Differential Signaling Shield for low swing signals

2. Surfliner:Transmission Line Model Differential Lossy Transmission LineSurfliner Shunt conductance G= 0 for wires of IC Add shunt conductance G= RC/L Flat response from DC to Giga Hz Telegraph Cable: O. Heaviside in 1887.

2. Surfliner: Distortionless Line Telegrapher’s equation: Propagation Constant: Wave Propagation: Alpha and Beta corresponds to speed and phase velocity.

2. Surfliner: Distortionless Lines Set G=RC/L Attenuation and Beta Characteristic impedance: (pure resistive) Phase Velocity (Speed of light in the media) Attenuation:

2. Surfliner: Distortionless Lines

2. Surfliner: Performance Speed of Light: 5ps/mm or 50ps/cm Power: 10mW at GHz Conductance variation = 10%, f=10MHz~10GHz Attenuation and velocity variation < 1%

2. Surfliner: Implementation Add shunt conductance Resistors realized by serpentine unsilicided poly, diffusion resistors, or high resistive metal

2. Surfliner: Simulation Results Characteristic Impedance (at 10GHz) : Ohm Inductance: 0.22nH/mm Capacitance: 141fF/mm Attenuation: 253mv magnitude at receiver’s end (assuming 1V at sender’s end) Using Microstrip (free space above the wires): impedance can be improved to 52.8Ohm

2. Surfliner: Settings Agilent ADS Momentum extract 4-port S-parameters HSpice: Transient analysis Assume 1023 bit pseudo random bit sequence (PRBS) 15GHz clock 10% of clock period transition slope for each rising and falling edge

2. Surfliner: Simulation Results 4 Stages 120 Stages

2. Surfliner: Simulation Jitter and silicon area usage #Stages Jitter (ps) Area (um 2 ) Power w/ different width and separation (w, s) (um)(3,3)(4,4)(5,4)(10,5) Power (mW) Attenuation

2. Applications of Surfliner 1.Clock distributions 2. Data communications: Buses Between CPUs, DSPs, Memory Banks

2. Application of Surfliner 3. High Performance Low Power Wafer Packaging

2. Surfliner: Current Status What we have done Derived a conservative design Performed simulation We are looking forward to Design and fabricate the test chip Explore architectures to exploit the advantages of Surfliner

Conclusion 1 Post Doc., 10 Ph.D. students work on interconnect, packaging, and simulation. Plan to release packages on interconnect planning (topology and design style). Need help on fabrication and measurement.