diseño para manufactura

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© 2006 LSI Logic Corporation Semiconductor Design for Manufacturability (DFM) T. R. Ramachandran Principal Program Manager Group Operations, Custom Solutions Group

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Transcript of diseño para manufactura

  • 2006 LSI Logic Corporation

    Semiconductor Design for Manufacturability (DFM)

    T. R. RamachandranPrincipal Program ManagerGroup Operations, Custom Solutions Group

  • Thursday, April 13, 2006 LSI Logic Confidential 2

    AcknowledgmentsDiscussions with the following people are gratefully acknowledged: Rich Schultz and Rich Laubhan (Silicon Methodology) Vishy Lakshmanan (Layout and Manufacturability Technology) John Walker (Technology Support/Foundry Technology) Ram Venkatraman and Ruggero Castagnetti (Strategic Planning

    and Architecture)

  • Thursday, April 13, 2006 LSI Logic Confidential 3

    Outline Why does DFM matter? Defining DFM

    ! What is DFM?! Why does it matter how we define DFM?! Characteristics of DFM! DFM: Yield/Reliability as Explicit Goals (Illustration)! DFM Decision Tree! A Framework for Understanding DFM! Defining and Bounding DFM

    Charting out a DFM Strategy Key Challenges in DFM Conclusions APPENDIX: Some Examples of DFM implementation at LSI

    Logic

  • Thursday, April 13, 2006 LSI Logic Confidential 4

    Why Does DFM Matter? DFM is about yield and reliability Lack of manufacturing access " less knowledge on

    process/yield/reliability learning Foundry-engagements often wafer-cost based

    ! Yield is not guaranteed (even reliability could be a question mark) After-the-fact FA on products is expensive, and sometimes

    unsuccessful Growing process technology (and design) complexity usually

    means greater uncertainty in scientific understanding! More parametric variation; possibly, greater sensitivity to variations! May lead to more design-specific yield/reliability risk

    Manufacturing data is more limited and cost of extracting data (through testchips) is growing rapidly

    " DFM, based on accurate manufacturing information, can therefore serve as a form of risk insurance

  • Thursday, April 13, 2006 LSI Logic Confidential 5

    What is DFM? Design for Manufacturability (or Design for Manufacturing)

    has been described in different ways. Some examples:! Manufacturing-aware design; design-dependent yield enhancement;

    design techniques to optimize manufacturability; design for yield; design through greater design-manufacturing collaboration; design for printability.and so on.

    ! Another perspective: Everything done in design is for manufacturing; so the term is a misnomer [Nitin Deo, Ponte Solutions]

    In some cases, articles about DFM dont clearly define or explain their use of the term! And we have an entire growing industry clustered around this term

  • Thursday, April 13, 2006 LSI Logic Confidential 6

    Why does it matter how we define DFM? You cant effectively solve the DFM problem if you dont know

    what DFM means! Vagueness may introduce redundancy, inefficiencies, or errors in judgment,

    without clarifying what exactly needs to be done differently Convincing management to fund DFM requires knowing what DFM is

    and what it isnt One complaint Ive read is that we sometimes dont know what data is

    needed for DFM- We wont know, if we dont know what DFM is

    The more well-defined DFM is, the more likely it is that -! The need for it will become transparent ! Companies serving this area will get traction with their customers

    Unified DFM definition and structured approach to DFM will not impact product differentiation! DFM is a broad topic with plenty of opportunities to support myriad products! Product differentiation is based on markets served in DFM arena

  • Thursday, April 13, 2006 LSI Logic Confidential 7

    Characteristics of DFM DFM involves Design and Manufacturability

    ! One cant design for manufacturability, without understandingmanufacturability

    ! DFM is not just about the D in DFM

    Yield is a key part of DFM; Reliability is also integrally linked to DFM! Usually, yield and reliability are linked but acceptable yield may

    not always guarantee acceptable reliability

    However, none of these four characteristics D, M, Y, R are unique to DFM! They are characteristics of every design and product ever built

    So, what makes DFM (somewhat) unique?! Yield and reliability need to be more explicit goals of design! Customer product yield and reliability need to be more explicit goals

    of manufacturing

  • Thursday, April 13, 2006 LSI Logic Confidential 8

    DFM: Yield/Reliability as Explicit Goals(An Oversimplified Illustration)

    Z = DFM Metric = F (Xdesign, Ydesign)= Yield or Reliability Probability

    Mfg/Tech. Requirements, M/R

    M/RX = SPICE Model

    Tightness (~ 1/)

    Y = De

    sign R

    ule

    Tightn

    ess (

    ~ 1/[L

    ,S])

    Mature mfg. process

    New, advanced mfg. process

    Actual Design, DE

    DE

    ? ??

    Product Requirements, P/RP/RSpeed

    Area

  • Thursday, April 13, 2006 LSI Logic Confidential 9

    DFM Decision TreeDoes full compliance to product requirements guarantee desired yield and reliability?

    Does the manufacturer guarantee desired yield and reliability if you comply 100% with their standard (mandatory) manufacturing requirements?

    NO

    Are you satisfied that the manufacturer has done sufficient due diligence and collected the

    data needed for them to make this guarantee?

    [requires some in-house process expertise!]

    YES

    Has the manufacturer provided a guarantee that

    planned process / manufacturing

    improvements will definitely address the assessedyield/reliability gaps?

    NO

    NO

    YES

    Consider DFM a requirement

    NO

    Consider DFM an option

    YES

  • Thursday, April 13, 2006 LSI Logic Confidential 10

    A framework for understanding DFM (1)Terms Used: The term Perturbations refers to deviations from nominal expectations

    Unavoidable perturbations are highly unlikely to be eliminated in a mature process and require design intervention

    Avoidable perturbations are those that manufacturing has the responsibility to eliminate as the process matures

    The term Model or Modeled is used loosely to also encompass design rules

    B = Nominal process and known perturbations with acceptable variation that are modeled accurately [Desired Baseline]

    UB = Known perturbations with unacceptable variation that are modeled accurately [Undesirable Baseline]

    KU = Known perturbations with unknown variation that are modeled inaccurately [Known Unknowns]

    UU = Unknown perturbations with unknown variation that are not modeled at all [Unknown Unknowns]

  • Thursday, April 13, 2006 LSI Logic Confidential 11

    A framework for understanding DFM (2):Illustrative (hypothetical) example

    UU KU UB BBetter knowledge of process and better modeling of variations/perturbations

    Avoidable perturbation? Manufacturing should take responsibility to eliminate perturbation

    Advanced mfg. pr

    ocess at introduct

    ion

    Advanced mfg. process a

    t maturity without DFM

    " The first step of DFM, then, is to develop an accurate understanding of unavoidable manufacturing perturbations, including their expected time evolution

    Unavoidable perturbation? Manufacturing to shift perturbation to UB/B, working with design if appropriate

    Advanced mfg. process at maturity, with DFM

    Count

  • Thursday, April 13, 2006 LSI Logic Confidential 12

    A framework for understanding DFM (3) Once the yield/reliability impacts of unavoidable manufacturing

    perturbations are accurately understood, manufacturing may decide to account for them in one of two ways:

    ! Update the standard manufacturing requirements (e.g., standard design rules, SPICE models, etc.)

    The designer would be responsible for complying 100%- This is the traditional design/foundry engagement model

    [or]

    ! Issue (optional) DFM requirements that are not addressed by the standard manufacturing and product requirements

    Designer would have to adequately account for them based on design-specific trade-offs (ROI)

    " The second step of DFM, then, is to adequately account forunavoidable manufacturing perturbations that are not addressed by the standard manufacturing and product requirements

  • Thursday, April 13, 2006 LSI Logic Confidential 13

    Defining and Bounding DFM DEFINITION: Two completely equivalent definitions are offered

    below. They are intentionally worded differently to call out the design and manufacturing aspects of DFM:

    ! DFM involves the accurate understanding of, and adequate accounting for, the time-dependent yield/reliability impact of unavoidable manufacturing perturbations which are not addressed by the standard manufacturing and product requirements

    ! DFM involves the identification and quantification of the design sensitivity of manufacturing yield and reliability, and the modification of design features to improve the yield or reliability of manufactured IP, without compromising on the standard manufacturing and product requirements

    SCOPE: The scope of DFM extends to design-related (not just design) activities that go above and beyond complying with standardmanufacturing and product requirements, in order to improve yield or reliability

  • Thursday, April 13, 2006 LSI Logic Confidential 14

    Charting out a DFM StrategyDFM Drivers

    Yield

    Reliability

    Broad Areas of Focus

    Process Variation

    Killer Defects

    Mask-making

    Possible Nature of Problems

    Process Modeling Gaps

    Defectivity Modeling Gaps

    Design Verification Gaps

    Design Rule Gaps

    Device and Interconnect Modeling Gaps

    How Problems will be Identified

    EDA Vendor models, expertise, roadmap

    Mfg. DFM rules, models, expertise, roadmap

    Internal expertise and learning

    Industry/academic research

    Yield Reliability

    Defining Solution Paths (Models, Tools, Utilities,

    Libraries, Decks, etc.)

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  • Thursday, April 13, 2006 LSI Logic Confidential 15

    Key Challenges in DFM (1) Focus on addressing design aspect of DFM often results

    in under-emphasis on understanding manufacturability

    ! Its not just about the D in DFM

    ! D and M " joint responsibility for DFM

    ! Meaningful DFM not possible without an accurate understanding of unavoidable manufacturing perturbations that impact yield/reliability

    Quantitative information, interdependencies, time evolution Inaccuracies could result in under- or over-compensation

    ! Need to press manufacturing partners on this consistently. If we dont:

    The value of DFM will remain nebulous, except in the most obvious of cases

    Foundries may be tempted to outsource their basic manufacturing and characterization responsibilities to their customers, for a fee

  • Thursday, April 13, 2006 LSI Logic Confidential 16

    Key Challenges in DFM (2) Wafer-cost business models are not naturally conducive to

    DFM

    ! Incentives for foundries to make yield/reliability (DFM) a key focus? Competition and Customer Service/Partnerships are two

    possibilities- Foundry customers should press foundries on product quality

    expectations (esp. yield/reliability)- Foundries should recognize that product yield/reliability can make

    or break customers success

    ! Incentives for designers to make yield/reliability (DFM) a key focus? Visible improvements in product yield and reliability

    - However, need accurate manufacturing information- Recommended rules alone dont help convince designers

    ! Recent developments (on the foundry front) are promising but its too early to make any judgments

  • Thursday, April 13, 2006 LSI Logic Confidential 17

    Key Challenges in DFM (3) Lack of common, open standards

    ! Is it really premature to talk standards for DFM? No.

    ! Standards for manufacturing information Companies should work together in consortia to define minimum

    acceptable manufacturing information and data/model formats OAC/Si2 could drive standards on formats

    ! Standards for design tools Embrace Open Access for application development Adopt minimum acceptable standards for tool calibration Ensure minimum acceptable standards for model robustness

    ! Standards for design companies Consider consortia-enabled collaboration on shared test vehicles

    for manufacturing and design tool benchmarking- Sometimes even basic silicon guarantees may not be met by

    manufacturer due to inadequate characterization

  • Thursday, April 13, 2006 LSI Logic Confidential 18

    Key Challenges in DFM (4) Circuit-Impact awareness of DFM design tools

    ! Lack of interoperability " circuit-impact of DFM enhancements likely cannot be determined in real-time

    Routing-friendliness of DFM design tools! DFM verification tools are sometimes not integrated into existing

    P&R flow! Some are not auto-correct and may or may not offer specific

    recommendations on fixes

    Manufacturing awareness of DFM design tools! Accurate interpretation of manufacturing information is important

    Options for DFM fixes linked to manufacturing knowledge Manufacturing variations - across die, reticle, wafer, lots, and

    time - not easily simplified into a single model! Holistic approach preferred to piecemeal approach

    Tools that cant make tradeoffs between different DFM requirements are of limited value

    ! DFM applications most often focus on the BEOL of the process Significant effects and issues in FEOL (and increasingly so)

  • Thursday, April 13, 2006 LSI Logic Confidential 19

    Key Challenges in DFM (5) TAT and Database Size

    ! Lack of parallel processing, incremental processing, and user-defined or circuit-property-dependent actions, will result in significant barriers to tool acceptance

    ! Database size explosion and massive TAT for even a single pass of DFM enhancement could be major roadblocks to adoption

    Dealing with Recommended Rules and Non-Traditional Rule Checks! Dealing with non-black-and-white rules, rules dependent on voltage

    domain or circuit intent, etc., not easy! Need data-based, effective solutions that also allow proper trade-off

    analysis

    Multiplicity of tools makes adoption challenging! The more (DFM) tools in the design flow, the greater the complexity

    and TAT and barrier to adoption

  • Thursday, April 13, 2006 LSI Logic Confidential 20

    Conclusions DFM involves the accurate understanding of, and adequate

    accounting for, the time-dependent yield/reliability impact of unavoidable manufacturing perturbations which are not addressed by the standard manufacturing and product requirements

    DFM requires:! Significant and accurate manufacturing information to make the

    design activity meaningful! Unprecedented collaboration between foundries, EDA vendors and

    design companies, using appropriate open standards (but encrypted data)

    ! Design tools that are efficient, more holistic, fast, user-friendly, standards-based, well-calibrated, platform-independent (or interoperable) and built using an informed interpretation of manufacturing data

    ! Adequate incentives for all parties to make it viable

    The future of the DFM industry depends on our being able to replace hype and fuzziness with sharp focus and clarity

  • 2006 LSI Logic Corporation

    APPENDIX: Some Examples of DFM Implementation at LSI Logic

  • Thursday, April 13, 2006 LSI Logic Confidential 22

    Some Examples of DFM Implementation at LSI Logic Analysis of OPC/litho process variations and library optimization

    for OPC/litho effects Development of more accurate device/interconnect models to fill

    gaps and inaccuracies in standard models from manufacturing! Extensive Si to Simulation analysis to expose potential problem

    areas! Accurate modeling and accounting of LOD effect, WPE, etc.

    DFM rule prioritization to help IP design, based on process knowledge and Si learning

    Adoption of select DFM rules for library design! Electrical analysis of impact of deviation from key DFM rules! Extensive use of key DFM rules and accurate models for

    analog/MXS IP Proprietary DFM testchip for defect and process sensitivity

    analysis Adoption of routing optimization for DFM (redundant via, metal

    extensions, etc.)! Based on yield sensitivity analysis and design tradeoffs

    Etc.