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ICCAD99 1
presents
High-Speed High-Accuracy 3D VLSI Extraction
ICCAD99 2
Motivation
�
Interconnects Now Dominate VLSI
"
Timing
"
Signal Integrity
�
Existing Interconnect Extractors Fail
"
Poor Accuracy & High Speed
"
Medium Accuracy & Very Low Speed
�
Need High-Speed High-Accuracy Extractor
0
20
40
60
80
100Gate
Interconnect
0.13 µm0.18 µm0.25 µm0.35 µm0.5 µm
Process Technology
Del
ay [%
]
ICCAD99 3
Overview
�
Company
�
Technology
"
High-speed High-accuracy BEM 3D Field Solver
"
Efficient Net-by-Net RC Extraction
�
Products
"
Extraction of Critical Cells, Blocks, Nets
"
Distributed RC Models
"
IR drop
"
Substrate Coupling
�
Differentiation
"
2D / 2.5D / 3D Tools
�
Summary
ICCAD99 4
Coyote Systems
�
History
"
Privately held, located in San Francisco CA
"
Founded in July 1996 by 3D Field Solver & MEMS experts
"
DARPA contract to develop extremely fast & easy-to-use 3D CAD for MEMS
�
Products
"
First MEMS product AutoMEMS® announced July 1998
"
First VLSI product AutoIC® announced June 1999
"
New Tools
- AutoIC® v2, AutoIC-SMP™, AutoNet™, AutoSubstrate™, AutoIRdrop™, AutoMEMS® v2
�
Customers
"
End-users include Siemens, Monterey, Analog Devices, Motorola, Texas Instruments, Hewlett-Packard, Sandia, MIT, Berkeley, CMU
"
OEM licenses include Monterey Design
ICCAD99 5
Company Mission
�
VLSI
�
MEMS
Provide premium high-speed high-accuracy solutions for extraction, timing, and signal integrity problems for modern VLSI designs.
Provide premium high-speed high-accuracy analysis of large, realistic MEMS devices.
ICCAD99 6
Coyote Products
�
Technology
�
VLSI
�
MEMS
"
AutoBEM
Fastest BEM field solver
"
AutoBEM-SMP
Exploit fine-grained parallelismon SMP computers
"
AutoIC
Capacitance extraction of interconnects
"
AutoIC-SMP
SMP support
"
AutoNet
Distributed RC models from layout
" AutoSubstrate Resistive coupling in substrate
" AutoIRdrop Potential drop in powergrid
" AutoMEMS Coupled electro/mechanical simulator
" AutoMEMS-SMP SMP support
ICCAD99 7
VLSI Geometries� Interconnects dominate performance
� Deep submicron is 3D" Huge layouts
" Intricate topologies
" IBM " AMD
ICCAD99 8
VLSI Extraction� RC Interconnect Extraction Tools
" High-Speed
" High-Throughput
" High-Capacity
" High-Accuracy
� Possible Alternatives
� Identify Advantages/Disadvantages
" 3D Field Solvers " Statistical Methods " Pattern Matchers
- Coyote Systems - QuickCap™ - Simplex
- Raphael™ - Frequency
- FastCap - Mentor
- Ultima
ICCAD99 9
Pattern Matchers� Why they are used
" Mature technology, Very Fast
" Requires 3D field solver to develop pattern library
� 2D/2.5D tools do not capture 3D DSM effects" Fast (<100,000 nets/hour) after
lengthy precharacterization (100-200 hours)
" Increasing difficulties with modern processes
- Many Layers, small feature sizes
- Arbitrary angles & non-manhattan geometries
- PCB-style variable wire width
- Increasing number of patterns needed
" Optimistic “error cancellation” - no bounded errors
" Large errors (>20%)
ICCAD99 10
Accuracy Problem!" Some pattern matching vendors claim <<10% errors
" Simple counterexample...
" 3D simulation reveals 20% errors using superpositioning!
" Geometric non-linearities prevent accurate solutions
≠ + +
3D Field Solver Pattern Matching
ICCAD99 11
Statistical Methods� Why are they sometimes used
" Alternative to FEM, FDM
" Reasonably good for Self-Cap & Small Problems
� Why will they not solve the problem" No Distributed R’s & C’s
" Very long run times with increasing number of nets
" Inaccurate Coupling Capacitance - Cij
" Only supports Manhattan Geometries
" Expensive support for multiple dielectrics
" Solves only part of the problem - Cii
ICCAD99 12
Alternative Solvers� Proposed Technologies
" FEM
" FDM
" Traditional BEM
� Why will they not solve the problem" Not fast enough
" Limited to very small problems
" Huge memory and CPU time requirements
� Computationally not feasible
ICCAD99 13
VLSI Extraction� Coyote combines advantages of all approaches!
" Field solver accuracy
" Pattern matcher speed & capacity
0
2 0
4 0
6 0
8 0
100
Accuracy
SpeedCapacity
Coyote
Field solver
Pattern matcher
ICCAD99 14
VLSI Geometries� Interconnects dominate performance
� Deep submicron is 3D
� 3D problems require 3D solutions!
" IBM " AMD" High aspect ratios
" Extreme Density
" Round Corners
" Cylindrical Vias
" Variable width wires
" Nonideal Cross-Sections
" Coyote can verify the effect of all these features!
- Simplex, Frequency, Avanti, Mentor, QuickCap™ cannot
ICCAD99 15
3D Field Solvers� Arbitrary Geometries
" PCB-style, manhattan & non-manhattan
� Arbitrary Materials" Planar & conformal dielectrics
� Arbitrary Boundary Conditions" Neumann, Dirichlet, mixed, floating
� Only Coyote’s AutoIC® solves everything!" AutoIC is faster, more accurate, and easier to use!
ICCAD99 16
3D Field Solvers� If field solver, then pick best field solver
" Simplest, smallest model
" Most accurate (states & gradients)
" Fastest runtime
" Lowest memory requirements
" Coyote uses Multipole Accelerated BEM
" Computational Scaling N^2 ➔ NlogN
BEM FEM
Direct Iterative Multipole Direct Iterative
Nr. nodes N^2 N^2 N^2 N^3 N^3
Memory N^4 N^4 (NlogN)^2 N^6 N^4.5
CPUtime N^6 N^4 (NlogN)^2 N^9 N^4.5
ICCAD99 17
AutoIC Field Solver� VLSI Interconnect Extraction
" Accelerated Boundary Element Method
" Automatic meshed 3D model from 2D layout
" Adaptive mesh refinement
" Robust automation
" Scriptable batch-mode or interactive GUI-mode operation
" Superset of Sematech extraction API
" Cluster & symmetric multiprocessing (SMP) support
ICCAD99 18
AutoIC Speed� AutoIC™ 3D Field Solver
" 2,000,000 BEM elements/hour per cpu
" 1,500 nets/hour per cpu (user selected <2% error)
� AutoIC vs. Field Solvers" 10-50x faster than QuickCap™
" 100-500x faster than Raphael™
� AutoIC vs. Library-based "Pattern Matchers"" Similar speed to Frequency
— 5 — 5/26/99 Copyright © 1999 by Frequency Technology, Inc. All rights reserved.
� Accuracy� +2.93% to -4.93% with no outliers
� Performance� Full accuracy / GDS mode : 500 nets /hour:
� Full accuracy / LEF- DEF mode : 2500 nets/hour
� “-fast” option (+/- 15% accuracy) : 6500 nets/hour
ICCAD99 19
AutoIC� Best Performance
" Faster than FastCap, QuickCap™, Raphael™, Space, etc.
" As fast as pattern matchers!
" Solves many more problems
" Large savings replacing multiple licenses
" Large engineering time savings
ICCAD99 20
Customer Tests� Motorola SRAM Evaluation
" Self-cap Extraction
" Cross-cap Extraction
" Convergence
" Time & Memory
" Model Generation
" Ease-of-Use
� Motorola Compared" AutoIC™
" QuickCap™
" Raphael™
ICCAD99 21
Motorola SRAM Cell
�
Convergence of bit-line self-capacitance
"
Require better than ±5% accuracy
�
AutoIC
"
10-100x faster!
"
Best convergence!
"
Tight error bounds!
0.00E+00
5.00E-16
1.00E-15
1.50E-15
2.00E-15
2.50E-15
1 1 0 1 0 0 1000 10000
cputime [sec] (AutoIC on 500MHz PentiumIII, others on 333MHz UltraII)
Cap
acit
ance
[F
]
AutoIC-constant
AutoIC-linear
Raphael
QC 0.01u
QC 0.005u
105%
95%
ICCAD99 22
Siemens Block� Extract Critical Nets
" 500 nets
" 1x1mm die
" 0.35um process
" 3 metal layers
" Multiple dielectrics
� AutoIC results" <2% Errors
" Excellent scaling
" 8mm/min extraction
" All nets extracted in 20 min using 1 cpu = 1,500 nets/hour
" All nets extracted in 1 min using 20 cpus = 30k nets/hour
0
2 0
4 0
6 0
0 2000 4000 6000 8000
Critical Net Length [um]
Ext
ract
ion
Tim
e [s
ec]
7700um/min
ICCAD99 23
Design Flow� Industry Std Layout
" GDSII, annotated GDSII, CIF, Sematech API
� 3D Model Generator" Flexible process descriptor
" API-mode or Batch-mode or GUI-mode
� 3D RC Extraction" Lumped, distributed
" API-mode or Batch-mode or GUI-mode
� Industry Std Output" Spice, Sematech API
" 3D visualization
ICCAD99 24
Model Generation� Input
" Layout
" Process Description
- Arbitrary layers
- Interlayer dielectrics
- Conformal dielectrics
� Output" Meshed 3D Model
ICCAD99 25
Applications� Critical Cells
" Coefficient generation
" Cell optimization
� Critical Blocks" IP characterization
" Routing
� Critical Nets" Clock trees, control lines
" User-selected nets
� Substrate Coupling
� IR drop" Power grid effects delays
ICCAD99 26
Critical Cells� AutoIC simulates 10,000 cells in 2 hours
" 1 AutoIC license replaces 50-200 Raphael™ licenses
" Adaptive meshing on SRAM bit-line shown
ICCAD99 27
Cell Optimization� AutoIC identifies where interactions occur
� Modify layout to optimize performance
" Magnitude of electrostatic flux on SRAM bit-line shown
ICCAD99 28
Critical Nets� Handles largest global nets
" Automatic tunneling around aggressor net
" 3D visualization indicates crosstalk areas
" Designer can modify layout to eliminate problem
" 1 AutoIC license replaces 10-50 QuickCap™ licenses
ICCAD99 29
Critical Blocks� PCB-style layout (Cypress)
" Non-manhattan Geometries
" Varying Linewidths
" AutoIC 500x faster than QuickCap™!
" Aggressor net, 3D tunnel & 3D mesh shown
ICCAD99 30
Non-Ideal Fabrication� AutoIC simulates Process Variations
" Any geometry
" Any material
� AutoIC correctly solves floating filler metal" Note that filler adds 20% to self-cap!
" Non-zero potential on floating filler shown
ICCAD99 31
AutoIC-SMP Scaling� Symmetric multiprocessing support
" Excellent scaling with every added CPU
" Accelerates both large and small nets
SMP Scaling for Critical Net Extraction
1
2
3
4
1 2 3 4
Number CPUs (Sun Ultra Enterprise 450)
Rel
ativ
e S
calin
g
Large Monterey benchmark
global net (control90 !RESET)
small net (control90 !n6969)
ICCAD99 32
"The Layout is the Design"
� Timing Delay" Self-capacitances dominate
� Signal Integrity" “Noise” or “Crosstalk”
" Cross-capacitances dominate
� AutoIC generates lumped RC models" Extracts high-accuracy 3D self-caps and cross-caps from the
interconnect layout
" 3D visualization identifies areas for correction
� AutoNet generates distributed RC models" Important differences between lumped and distributed
simulations
ICCAD99 33
AutoNet� Go from Layout to Distributed Spice
� Variable model size" Lumped net =
1 segment
" Distributed net = multiple segments
� Segments" Spice star-model for each
segment
" Created from layout
" Cross-caps between segments
" Compact Spice model size
" No model reduction needed
A B
C
D
a b
T1
T2
V1
V2
V3
T3
T4T5
Segment1
A B
C D
a
b
V3
T1
T2
V2
V1 T3
T5
T4
Segment1Segment3
Segment2
Segment4
Segment5
ICCAD99 34
AutoNet� Automatic segmentation
" 5 segments on Net1
" 4 segments on Net2
� Distributed RC spice model" Each segment has self-capacitance
" Each segment has cross-capacitances to segments on other nets
Net2
Net1
a b c d
A
B
C D E
A B C D
E
ab
c
d
ICCAD99 35
AutoNet� Parallel bus lines
" Generated distributed model(8 segments per net)
" Generated lumped T-model(1 segment per net)
" Step Response
- Distributed and T model responses similar
" Coupling
- Distributed and lumped responses similar
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.2
0.4
0.6
0.8
1
time [ps]
volts
Crosstalk
Vin8 segmentsT-model
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.2
0.4
0.6
0.8
1
time [ps]
volts
Unit step response
Vin8 segmentsT-model
ICCAD99 36
AutoNet� Non-uniform bus lines
" Generated distributed model(4-5 segments per net)
" Generated lumped T-model(1 segment per net)
" Step Response
- Distributed and T model responses similar
" Coupling
- 2x more noise on distributed model
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.2
0.4
0.6
0.8
1
time [ps]
volts
Unit step responses
Vin4/5 segmentsT-model
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.2
0.4
0.6
0.8
1
time [ps]
volts
Crosstalk
VinVictim A, 4/5 segmentsVictim B, 4/5 segmentsVictim A, T-modelVictim B, T-model
Victim A
Victim B
Aggressor
ICCAD99 37
AutoNet� Parallel lines with varying cross-section
" Net1 switches
" Step Response
- Distributed and T models similar
- Commonly used self-cap model is inaccurate
" Coupling
- 30% larger noise with distributed model
0 10 20 30 40 50 60 70 80 90 1000
0.2
0.4
0.6
0.8
1
1.2
time [ps]
volts
[V]
Unit step response and coupling effects
Vinresponse, 4/5 segmentsresponse, T-modelresponse, self capacitancecoupling, 4/5 segmentscoupling, T-model
Net2
Net1
ICCAD99 38
AutoNet� Non-uniform parallel lines
" Nets switch in opposite directions
" Step Response
- Distributed and T models similar
" Coupling
- Distributed model shows non-monotonic behavior
0 10 20 30 40 50 60 70 80 90 1000
0.2
0.4
0.6
0.8
1
1.2
time [ps]
volts
[V]
High/low switch response
Vin1
Vin2
Vout1, 4/5 segments
Vout1, T-model
Vout2, 4/5 segments
Vout2, T-model
Net2
Net1
Non-monotonic
ICCAD99 39
AutoNet� Clock Tree Skew
" Hierarchical H-shaped layout
" 256 terminals
" RC model with 70 segments
" Non-constant clock skew due to cross capacitances
" 20% clock skew at 3 random clock terminals!
0 20 40 60 80 100 120 140 160 180 2000
0.2
0.4
0.6
0.8
1
time [ps]
volts
[V]
Clock skew
VinVout
1Vout
2Vout
3
sample segments
ICCAD99 40
AutoNet� Compare Floating Filler & Grounded Filler
" 3x3 crossing bus
" Net1 switches
� Significant filler problem" 25% difference in risetime
" 9x increase in noise level
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.2
0.4
0.6
0.8
1
time [ps]
volts
[V]
Unit step response, filler floating / grounded
VinVout
1, floating filler
Vout1, grounded filler
Vout2, floating filler
Vout2, grounded filler
Vout3, floating filler
Vout3, grounded filler
Net1Net2
Net3
ICCAD99 41
AutoIRdrop� AutoIC solves 3D field
outside interconnects
� AutoIRdrop solves 2D/3D field inside interconnects" Varying angles, width,
cross-section
" Vias
" Aluminum, copper
" Current sink/source
� 2D/3D Field Solver" Solves potential drop
- Resistance
" Solves current density through wire
- Enables electromigration analysis
1
2
3
4
ICCAD99 42
AutoIRdrop� "Naive" Resistance Network
" N-ports require N simulations, resulting in N2 resistances
� "Smart" Resistance Network" N-ports require N simulations,
resulting in N resistances
� Field Simulation" 2D resistance is very accurate,
much faster than 3D
" 2D suitable for resistance,3D suitable for capacitance
1 2
3 4
1
2 3
4
ICCAD99 43
AutoSubstrate� Solves 3D field
inside substrates" Contacts
" Multiple materials
� 3D Field Solver" Solves potential
distribution
" Solves electrostatic flux distribution
" Solves current density through contacts
12
34
56
7
89
10
ICCAD99 44
AutoSubstrate� Resistance Network
" Resistance calculated from calculated current densities
" Resistor for every port-port interaction
" Automatic spice model
12
34
56
78
910
12
34
56
78
910
0
2
4
6
8
10
12
x 105
PortPort
Ohm
ICCAD99 45
Shipping Now� Fastest, Most accurate, Easiest to use
" Replace multiple tools
" Large engineering time savings
� Licenses" End-user licenses
" OEM, Embedded licenses
� Available Now" Sun, Linux, HP platforms
" Uniprocessor & SMP configurations
ICCAD99 47
For More Information
� http://www.coyotesystems.com
� Contact" Dr. Per Ljung
2740 Van Ness Ave. #210San Francisco, CA 94109(415) 346 4223 [email protected]