The Roadmap for Design and Design for Manufacturing Andrew B. Kahng, UC San Diego CSE

1
The Roadmap for Design and Design for
Manufacturing Andrew B. Kahng, UC San Diego
CSE ECE DepartmentsChair, ITRS Design ITWG,
20012003ISMT Yield Council, September 25, 2003
2
Outline

• The Design Roadmap
• DFM Symptoms, Problem, Solution
• DFM Futures Some Examples

3
Design ITWG Contributions to ITRS

• System Drivers Chapter
• Defines IC products that drive manufacturing and
  design technologies
• ORTCs System Drivers framework for technology
  requirements
• Four System Driver classes
• SOC (Low-Power, High-Performance,
  Mixed-Technology)
• MPU
• Mixed-Signal
• Embedded Memory
• Design Chapter
• Design cost and productivity models
• Five technology areas design process / design
  system architecture, system-level design,
  logical/physical/circuit design, design
  verification, design test
• Cross-cutting challenges productivity, power,
  manufacturing integration, interference,
  error-tolerance
• ORTC support
• Frequency, Power, Density models

4
Big Picture

• Message Cost of Design threatens continuation
  of the semiconductor roadmap
• Design cost model
• Challenges are now Crises
• Strengthen bridge from semiconductors to
  applications, software, architectures
• Hertz and bits are not the same as efficiency and
  utility
• System Drivers chapter, with productivity and
  power foci
• Strengthen bridges among ITRS technologies
• Shared red bricks can be solved (or,
  worked-around) more cost-effectively
• Manufacturing Integration cross-cutting
  challenge
• Living ITRS framework to promote consistency
  validation

5
Design-Manufacturing Integration

• ITRS Design Chapter Manufacturing
  Integration one of five Cross-Cutting
  Challenges
• Goal share red bricks with other ITRS
  technologies
• Lithography CD variability requirement ? new
  Design techniques that can better handle
  variability
• Mask data volume requirement ? solved by
  Design-Mfg interfaces and flows that pass
  functional requirements, verification knowledge
  to mask writing and inspection
• ATE cost and speed red bricks ? solved by DFT,
  BIST/BOST techniques for high-speed I/O, signal
  integrity, analog/MS
• Does X initiative have as much impact as copper?

6
Living ITRS Framework

• Living roadmap internally consistent,
  transparent models as basis of ITRS predictions

• ORTCs Models for layout density, system clock
  speed, total system power in various drivers,
  circuit fabrics
• Visualization tool (at Sematech website) for
  capture, exploration of ITRS models under
  alternative scenarios
• Is --- worth it?

7
System Drivers Chapter

• Defines the IC products that drive manufacturing
  and design technologies
• Goal ORTCs System Drivers consistent
  framework for technology requirements
• Starts with macro picture
• Market drivers
• Convergence to SOC
• Main content System Drivers
• SOC focus on low-power PDA (and,
  high-speed I/O)
• MPU traditional processor core
• AM/S four basic circuits and Figures of Merit
• Embedded Memory eDRAM, eSRAM, eNVM (flash)

8
MPU Driver

• Two MPU flavors
• Cost-performance (mobile) constant 140 mm2
  die
• High-performance (server/desktop) constant
  310 mm2 die
• Stake in ground 1 MPU organization multiple
  cores, on-board L3 cache
• More dedicated, less general-purpose logic
• More cores help power management (lower
  frequency, lower Vdd, more parallelism ? overall
  power savings)
• Reuse of cores helps design productivity
• Redundancy helps yield and fault-tolerance
• MPU and SOC converge (organization and design
  methodology)
• Stake in ground 2 No more doubling of clock
  frequency at each node

9
FO4 INV Delays Per Clock Period

• FO4 INV inverter driving 4 identical inverters
  (no interconnect)
• Half of freq improvement has been from reduced
  logic stages

10
SOC Low-Power Driver Model (STRJ)

• SOC-LP PDA system
• Composition CPU cores, embedded cores,
  SRAM/eDRAM
• Requirements IO bandwidth, computational power,
  GOPS/mW, die size
• Drives PIDS/FEP LP device roadmap, Design power
  management challenges, Design productivity
  challenges

11
Reqd Performance for Multi-Media Processing
GOPS
0.01
0.1
1
10
100
Video
MPEG1 Extraction
Compression
MPEG2 Extraction
MP/ML
MP/HL
MPEG4
JPEG
Audio Voice
Sentence Translation
Dolby-AC3
Voice Auto Translation
MPEG
Word Recognition
Graphics
3D Graphics
10Mpps
100Mpps
2D Graphics
Communication Recognition
SW Defined Radio
VoIP Modem
Face Recognition
Modem
Voice Print Recognition
Moving Picture Recognition
FAX
GOPS Giga Operations Per Second
12
ANALOGY 1

• ITRS is like a car
• Before, two drivers (husband MPU, wife DRAM)
• The drivers looked mostly in the rear-view mirror
  (destination Moores Law)
• Many passengers in the car (ASIC, SOC, Analog,
  Mobile, Low-Power, Networking/Wireless, )
  wanted to go different places
• Starting in 2001 ITRS (System Drivers Chapter)
• Some passengers became drivers
• All drivers explain more clearly where they are
  going

13
Design Challenges - Silicon

• Silicon Complexity impact of process scaling,
  new materials, new device/interconnect
  architectures
• Non-ideal scaling (leakage, power management,
  circuit/device innovation, current delivery)
• Coupled high-frequency devices and interconnects
  (signal integrity analysis and management)
• Manufacturing variability (library
  characterization, analog and digital circuit
  performance, error-tolerant design, layout
  reusability, static performance verification
  methodology/tools)
• Scaling of global interconnect performance
  (communication, synchronization)
• Decreased reliability (SEU, gate insulator
  tunneling and breakdown, joule heating and
  electromigration)
• Complexity of manufacturing handoff (reticle
  enhancement and mask writing/inspection flow,
  manufacturing NRE cost)

14
Design Challenges - System

• System Complexity exponentially increasing
  transistor counts, with increased diversity
  (mixed-signal SOC, )
• Reuse (hierarchical design support, heterogeneous
  SOC integration, reuse of verification/test/IP)
• Verification and test (specification capture,
  design for verifiability, verification reuse,
  system-level and software verification, AMS
  self-test, noise-delay fault tests, test reuse)
• Cost-driven design optimization (manufacturing
  cost modeling and analysis, quality metrics,
  die-package co-optimization, )
• Embedded software design (platform-based system
  design methodologies, software verification/analys
  is, codesign w/HW)
• Reliable implementation platforms (predictable
  chip implementation onto multiple fabrics,
  higher-level handoff)
• Design process management (team size / geog
  distribution, data mgmt, collaborative design,
  process improvement)

15
Design Chapter Outline

• Introduction
• Scope of design technology
• Complexities (silicon, system)
• Design Cross-Cutting Challenges
• Productivity
• Power
• Manufacturing Integration
• Interference
• Error-Tolerance
• Details of five traditional technology areas
  Design Process, System-Level, Logical/Physical/Cir
  cuit, Functional Verification, Test
• Key 2003 changes
• Increased analog and circuits content
• Refinement of design cost metrics
• Design system architecture and flow
• SEU and reliability

16
Design Technology Crises
Incremental Cost Per Transistor
Test
Manufacturing
Manufacturing
SW Design
NRE Cost
Turnaround Time
Verification
HW Design

• 2-3X more verification engineers than designers
  on microprocessor teams
• Software 80 of system development cost (and
  Analog design hasnt scaled)
• Design NRE gt 10s of M ?? manufacturing NRE 1M
• Design TAT months or years ?? manufacturing TAT
  weeks
• Without DFT, test cost per transistor grows
  exponentially relative to mfg cost

17
Design Cost Model

• Engineer cost per year increases 5 / year
  (181,568 in 1990)
• EDA tool cost per year (per engineer) increases
  3.9 per year
• Productivity due to 8 major Design Technology
  innovations
• RTL methodology
• Large-block reuse
• IC implementation suite
• Intelligent testbench
• Electronic System-level methodology
• Matched up against SOC-LP PDA content
• SOC-LP PDA design cost 15M in 2001
• Would have been 342M without EDA innovations

18
Design Cost of SOC-LP PDA Driver
19
Cross-Cutting Challenge Productivity

• Overall design productivity of normalized
  functions on chip must scale at 4x per node for
  SOC Driver
• Reuse (including migration) of design,
  verification and test effort must scale at gt
  4x/node
• Analog and mixed-signal synthesis, verification
  and test
• Embedded software productivity

20
Cross-Cutting Challenge Power

• Reliability and performance analysis impacts
• Accelerated lifetime testing (burn-in) paradigm
  fails
• Large power management gaps (standby power for
  low-power SOC dynamic power for MPU)
• Power optimizations must simultaneously and fully
  exploit many degrees of freedom (multi-Vt,
  multi-Tox, multi-Vdd in core) while guiding
  architecture, OS and software

21
Cross-Cutting Challenge Interference

• Lower noise headroom especially in low-power
  devices
• Coupled interconnects
• Supply voltage IR drop and ground bounce
• Thermal impact on device off-currents and
  interconnect resistivities
• Mutual inductance
• Substrate coupling
• Single-event (alpha particle) upset
• Increased use of dynamic logic families
• Modeling, analysis and estimation at all levels
  of design

22
Cross-Cutting Challenge Error-Tolerance

• Relaxing 100 correctness requirement may reduce
  manufacturing, verification, test costs
• Both transient and permanent failures of signals,
  logic values, devices, interconnects
• Novel techniques adaptive and self-correcting /
  self-repairing circuits, use of on-chip
  reconfigurability

23
Challenge Manufacturing Integration

• Goal share red bricks with other ITRS
  technologies
• Lithography CD variability requirement ? new
  Design techniques that can better handle
  variability ?
• Mask data volume requirement ? new Design-Mfg
  interfaces and flows that pass functional
  requirements, verification knowledge to mask
  writing and inspection ?
• ATE cost and speed red bricks ? new DFT,
  BIST/BOST techniques for high-speed I/O, signal
  integrity, analog/MS ?
• Can technology development reflect ROI (value /
  cost) analysis Who should solve a given red
  brick?
• Shared Red Bricks

24
Example Manufacturing Test

• High-speed interfaces (networking, memory I/O)
• Frequencies on same scale as overall tester
  timing accuracy
• Heterogeneous SOC design
• Test reuse
• Integration of distinct test technologies within
  single device
• Analog/mixed-signal test
• Reliability screens failing
• Burn-in screening not practical with lower Vdd,
  higher power budgets ? overkill impact on yield
• Design Challenges DFT, BIST
• Analog/mixed-signal
• Signal integrity and advanced fault models
• BIST for single-event upsets (in logic as well as
  memory)
• Reliability-related fault tolerance

25
Example Lithography

• 10 CD uniformity requirement causes red bricks
• 10 lt 1 atomic monolayer at end of ITRS
• This year Lithography, PIDS, FEP agreed to
  relax CD uniformity requirement (but we still see
  red bricks)
• Design challenge Design for variability
• Novel circuit topologies
• Circuit optimization (conflict between slack
  minimization and guardbanding of quadratically
  increasing delay sensitivity)
• Centering and design for /wafer
• Design challenge Design for when devices,
  interconnects no longer 100 guaranteed correct
• Can this save in manufacturing, verification,
  test costs?

26
ANALOGY 2

• ITRS technologies are the parts of the ITRS car
• Every one takes the engine point of view when
  it defines its requirements
• Why, you may take the most gallant sailor, the
  most intrepid airman, the most audacious soldier,
  put them at a table together what do you get?
  The sum of their fears. - Winston Churchill
  (quoted by Paolo Gargini)
• But, all parts must work together to make the car
  go smoothly
• Need global optimization of requirements
• ? Shared Red Bricks

27
Outline

• The Design Roadmap
• DFM Symptoms, Problem, Solution
• DFM Futures Some Examples

28
Symptoms Routing Rules (1)

• Minimum area rules and via stacking
• Stacking vias through multiple layers can cause
  minimum area violations (alignment tolerances,
  etc.)
• Via cells can be created that have more metal
  than minimum via overlap (used for intermediate
  layers in stacked vias)
• Multiple-cut vias
• Use multiple-cut vias cells to increase yield and
  reliability
• Can be required for wires of certain widths
• Multiple via cut patterns have different spacing
  rules
• Four cuts in quadrilateral five cuts in cross
  six cuts in 2x3 array
• With wide-wire spacing rules, complicates pin
  access
• Cut-to-cut spacing rules ? check both cut-to-cut
  and metal-to-metal when considering via-to-via
  spacing
• Line-end extensions
• Vias or line ends need additional metal overlap
  (0th-order OPC)

29
Symptoms Routing Rules (2)

• Width- and Length-dependent spacing rules
• Width-dependent rules domino effects
• Variant parallel-run rule (longer parallel
  runs ? more spacing)
• Measuring length and width halo rules affect
  computation
• Influence rules or stub rules
• A fat wire, e.g., power/ground net, will
  influence the spacing rule within its
  surroundings ? any wire that is X um away from
  the fat wire needs to be at least Y um away from
  any other geometry.
• Example fat wire with thin tributaries
• bigger spacing around every wire within certain
  distance of the thin tributaries
• ECO insertion of a tributary causes complications
• Strange jogs and spreading when wires enter an
  influenced area

30
Example LEF/DEF 5.5, April 2003
31
Example LEF/DEF 5.5, April 2003
32
Symptoms Routing Rules (3)

• Density
• Grounded metal fills (dummy fill)
• Via isodensity rules and via farm rules (via
  layers must be filled and slotted, have
  width-dependent spacing rule analogs, etc.)
• Non-rectilinear (?-geometry) routing
• X-Architecture http//www.xinitiative.org/
• Y-Architecture http//vlsicad.ucsd.edu/Yarchitec
  ture/ , LSI Logic patents
• Landing pad shapes (isothetic rectangle vs.
  octagon vs. circle), different spacings (1.1x)
  between diagonal and Manhattan wires, etc.
• More exceptions
• More non-default classes (timing, EM reliability,
  )
• Not just power and clock
• gt0.25um width may be wide ? many exceptions

33
Symptoms Routing Rules

• Degrade completion rates, runtime efficiency
• Postprocessing likely no longer suffices
• E.g., antennas
• There is no chip until the router is done
• Must / Should / Can tomorrows IC routers
  independently address these issues?

34
Whose Job Is It To Solve

• Mask NRE cost (? runtimes ? shapes
  complexity)
• BEOL catastrophic yield loss
• Deposited copper ? can infer yield loss
  mechanisms
• Open faults more prevalent than short or bridging
  faults
• High-resistance via faults
• Cf. non-tree routing for reliability and yield?
• Variability budget for planarization
• Copper is soft ? dual-material polish mechanisms
• Oxide erosion and copper dishing ?
  cross-sectional variability, inter-layer bridging
  faults,
• Low-k thermal properties, anisotropy,
  nonuniformity
• Resistivity at small conductor dimensions

35
The Problem Evolution

• Conflicting goals
• Designer freedom, reuse, migration
• EDA maintenance mode
• Process/foundry enhance perceived value
  ( add rules)
• ? Prisoners Dilemma who will invest in change?
• Fiddling Incremental, linear extrapolation of
  current trajectory
• GDS-3
• Thin post-processing layers (decompaction, RET
  insertion, )
• Leads to dark future (12th Japan DA Show
  keynote)

36
DAC-2003 Nanometer Futures PanelWhere should
extra RD be spent?
37
The Solution Co-Evolution

• Designer, EDA, and process communities cooperate
  and co-evolve to maintain the cost (value)
  trajectory of Moores Law
• Must escape Prisoners Dilemma
• Must be financially viable
• At 90nm to 65nm transition, this is a matter of
  survival for the worldwide semiconductor industry
• Example Focus Areas
• Explicit manufacturability and cost/value
  optimization
• Restricted layout
• Intelligent mask data prep
• Analog (not binary) rules
• (Many layout and design optimizations)
• Disclaimer Not a complete listing

38
Foundation of the (DFM) Solution

• Bidirectional design-manufacturing data pipe
• Fundamental drivers cost, value
• Pass functional intent to manufacturing flow
• Example RET for predictable timing slack,
  leakage, yield
• RETs should win , reduce performance variation
  
• ? cost-driven, parametric yield constrained RET
• Pass limits of manufacturing flow up to design
• Example avoid corrections that cannot be
  manufactured or verified ? e.g., design should be
  aware of metrology
• N.B. 1998-2003 papers/tutorials
  http//vlsicad.ucsd.edu/abk/TALKS/

39
Outline

• The Design Roadmap
• DFM Symptoms, Problem, Solution
• DFM Futures Some Examples

40
1 Design for Value

• Mask cost trend ? Design for Value (DFV)
• Design for Value Problem
• Given
• Performance measure f
• Value function v(f)
• Selling points fi corresponding to various values
  of f
• Yield function y(f)
• Maximize Total Design Value ?i y(fi)v(fi)
• or, Minimize Total Cost
• Probabilistic optimization regime
• See "Design Sensitivities to Variability
  Extrapolation and Assessments in Nanometer VLSI",
  IEEE ASIC/SoC Conference, September 2002, pp.
  411-415.

41
Obvious Step Function-Aware OPC

• Annotate features with required amount of OPC
• E.g., why correct dummy fill?
• Determined by design properties such as setup and
  hold timing slacks, parametric yield criticality
  of devices and features
• Reduce total OPC inserted (e.g., SRAF usage)
• Decreased physical verification runtime, data
  volume
• Decreased mask cost resulting from fewer features
• Supported in data formats (OASIS, IBM GL-I,
  OA/UDM)
• Design through mask tools need to make, use
  annotations
• (General RET trajectory rules ? models ?
  libraries!)

42
MinCorr Minimum Mask Complexity

• Levels of RET Levels of CD control

• Levels of RET levels of CD control

Type of OPC Ldrawn (nm) 3? of Ldrawn Figure Count Delay (?, ?) for NAND2X1
Aggressive 130 5 5X (60.7, 7.03)
Medium 130 6.5 4X (60.7, 7.47)
No OPC 130 10 1X (60.7, 8.79)
OPC solutions due to K. Wampler, MaskTools,
March 2003
CD studies due to D. Pramanik, Numerical
Technologies, December 2002
43
MinCorr Methodology (DAC-03)

• Mapping of area minimization to RET cost
  optimization
• Yield library analogous to timing libraries
  (e.g., .lib)
• ? Off-the-shelf synthesis tool performs OPC
  sizing
• Up to 79 reduction in figure complexity without
  any parametric yield impact

Gate Sizing ? MinCorr
Cell Area ? Cost of correction
Nominal Delay ? Delay (?k?)
Cycle Time ? Selling point delay
Die Area ? Total cost of OPC
44
2 Process-Aware Design

• Anisotropy in H vs. V bias
• Features in one direction (scanning, raster
  write, ) may be better controllable than those
  in the orthogonal direction
• Single orientation throughout layout is preferred
• Dominant (critical-feature) orientation in layout
  design should match write direction
• Wafer symmetries (e.g., etch gradient due to
  spin-on)
• Iso-Dense balancing (imaging through focus)

45
3 Intelligent MDPWrite

• MDP driven by (write error MEEF) wafer CD
  error
• Partitioning into multiple gray-scale writing
  passes
• Apertures, beam currents, dwell times, shot
  ordering,
• EDA tools define stripe, major field, subfield
  boundaries!
• Electrical / functional defect criteria

46
4 Mask Write Optimizations

• Conflicting goals resolution, CD control,
  throughput
• Resist heating large contributor to mask CD
  variation
• Knobs beam current, flash size, idle times,
  grayscale passes
• Subfield writing order example new knob
• Reduced heating ? increased beam current density
• Reduced dwell time compensates for travel and
  settling time

1 2 3 4
8 7 6 5
9 10 11 12
16 15 14 13
1 13 5 9
6 10 2 14
3 15 7 11
8 12 4 16
Ordering 1
Ordering 2

• Ordering 2 is self-avoiding ? lower pre-flash
  temps

47
Self-Avoiding Subfield Order for Mask Write

• SPIE Microlithography 03, Photomask Japan 03
• Simulation of subfield temperatures within a main
  deflection field for sequential vs. greedily
  optimized writing schedules

Max 32.68?C Mean 16.07?C
Greedily optimized schedule
48
5 Fill Parametric Yield Impact

• Performance Impact Limited Fill (PIL-Fill),
  DAC-2003
• Fill adds capacitance, hurts timing and SI
  closure
• Plain capacitance minimization objective is not
  sufficient
• CMP modeling ? layout density vs. dimensions
  built into RLCX

1
top view
Active lines
2
B
A
C
Active lines
3
w
fill grid pitch
D
E
4
5
buffer distance
F
G
6
49
Min-Slack, Fill-Constrained PIL-Fill

• Inputs LEF/DEF, extracted RSPF, STA (slack)
  report
• Drive ILP and greedy PIL-Fill methods by
  estimated lateral coupling and Elmore delay
  impact
• Baseline comparison LP/Monte-Carlo methods
• Iterated greedy method for MSFC PIL-Fill reduces
  timing slack impact of fill by 80 (average over
  all nets), 63 (worst net)

50
6 Analog Rules

• We dont need no ((! rules
• Rules just make lithographers feel better (?)
• Ultimately, bottom line is cost of ownership,
  TCOG
• Given adequate models of MDP, RET and Litho
  flows, design tools can and should optimize
  parametric yield, /wafer, profits
• More examples critical-area reduction by
  decompaction, introducing redundancy (vias,
  wires),
• Automated learning of models and implicit rules
• Current approach test wafers, test structures,
  second-hand understanding
• Future machine learning techniques

51
7 Restricted Layout

• Soft reset 1-time hit on Moores Law density
  scaling
• Restricted Design Rules (RDR) can be
  compensated many ways
• embedded 1-T SRAM fabric, stacking, I/O circuit
  design,
• N.B. Moores Law is a meta Law!

Dual Exposure Result
Islands
Checkerboard
Example PhasePhirst! (Levenson et al.)
0?
180?
Transparent
Opaque
Trim Mask Exposure
First Exposure
Dark-Field PSMs
or
M. D. Levenson, 2003
52
Pre-Made Mask Blanks

• PhasePhirst!
• Levenson/Petersen/Gerold/Mack, BACUS-2000
• Idea mask blanks can be mass-produced and stored
  to reduce average cost (e.g., 10K), then
  customized on demand

M. D. Levenson, 2003
53
Notes on Regular Layout

• 65 nm has high likelihood for layouts to look
  like regular gratings
• Uniform pitch and width on metal as well as poly
  layers
• ? Predictable layouts even in presence of focus
  and dose variations
• More manufacturable cell libraries with regular
  structures
• New layout challenges (e.g., preserving
  regularity in placement)
• Caveats
• Non-minimum width poly is less susceptible to
  variation ? larger devices (with same W/L) may
  lead to more robust designs (so, selective
  upsizing may be an alternative to regular
  layouts)
• 180nm node is a sweet spot for cost,
  analog/mixed-signal integration, etc. ? more and
  more technology nodes will tend to coexist

54
7 Charging and Antennas

• Process steps use plasmas, charged particles
• Electrical fields over gate oxides induce damage
  (Vt shift) or breakdown
• Limit antenna ratio (Apoly AM1 ) /
  Agate-ox
• AMx metal(x) area that is electrically
  connected to node without using metal (x1), and
  not connected to an active area
• Bridging (break antenna by hopping to higher
  layer)
• Extra wiring, vias, congestion
• Reverse-biased diode or source-drain contact near
  gate
• Leakage, area, timing penalties
• Will antenna ratios continue to decrease?
• High-k gate dielectrics ? increased physical Tox
  ? less leaky, hard failure modes?
• More preemption (no post-processing, or dioded
  cells)?
• Tradeoff unfixed antenna yield penalty for fixed
  antenna yield loss?

55
8 Pattern Collapse

• Pr(pattern collapse) f(length)
• ? Length-dependent spacing rules
• Limits wire AR, packing density

• Standardized embedding of long wires for
  manufacturability and physical reliability
• becomes
• ???

Cao et al. U. Wisconson
56
9 Data Compression

• Today RET complexity ? exploding data volume
• Partitioning of compression and decompression?
• Equipment architecture question where to put
  engines, I/Fs, storage?
• Largely orthogonal to design considerations
• Procedural compression largely unexplored? (Ex
  Verilog SPR binaries runscripts
  representation of detail-routed layout)
• Design for compressibility? (DATE 03, SPIE ML
  03)
• What is ROI of relaxing constraints on layout? Of
  k bytes of data?
• How context-sensitive must patterning be?
  (Lessons from RET)
• Use of lossy compression? (SPIE ML 03)
• What design features can be lost? (Ex dummy
  fill)

57
Choice of Geometric Compression Operators

• Who is using compression, at what stages of
  design-mfg flow?
• Is there synergy between manufacturing
  flow and
  GDSII-OASIS-UDM?

OASIS Format (recent SEMI standard) defines eight
repetition types. A repetition represents an
array of (polygon) records, enabling
compression of layout data.
equivalent to GDSII AREF
Other OASIS repetition types
58
10 Leakage Management

• Huge parametric yield loss
• Subthreshold leakage current varies exponentially
  with threshold voltage I ? exp(-Vth)
• Vth f(channel length, oxide thickness, doping)
• Most affected by variations in gate length

100 Isub
10 Ld
Dennis Sylvester, U. Michigan
59
Leakage Understanding Control

• Understanding variation in chip-level leakage
  due to intra- and inter-die Leff variation
• cost-benefit of controlling relevant variation
  sources
• Control Multi-everything (threshold, supply,
  sizing)
• New control can use selective Lgate bias (2 nm)
  to reduce leakage by 60 with no loss in critical
  path delay
• Draft in preparation

60
Conclusions

• Designer, EDA, and mask communities must
  co-evolve to maintain the cost (value) trajectory
  of Moores Law
• Wakeup call Intel 157nm announcement
• Basic goal bidirectional design-mfg data pipe
• Drivers cost, value
• Pass functional intent to mask and foundry flows
• Pass limits of mask and foundry flows up to
  design
• Several examples given
• Manufacturability and cost/value optimization
• Leakage power
• Restricted layout
• Intelligent mask data prep
• Analog rules
• Please pay someone to do this!

61
THANK YOU !