Are There Economic Benefits in DFM

Are There Economic Benefits in DFM ? - a Fabless Design House Perspective Riko Radojcic Matt Nowak

What IS DFM to Qualcomm ? n n DFM = everything that a designer can do to ensure that the product meets its performance, power and cost targets Tight design to process coupling for : Ø Ø Ø Litho effects = to CMP effects = to Variability = to Random effects = to Act of God effects = get get what you see in x-y plane what you see in z-plane what you simulate electrically the yield that you modeled to get the operating margins you need So …. ? n DFM = everything that the foundry partner tells you to do ? n DFM = everything that the EDA supplier says you can do ? n DFM = everything that the ‘DFM Start Ups’ say you should do ? n DFM = everything that the designer thinks he should do ? n DFM = business as before and hope for the best ?

What is the Big Deal about DFM ? n n Process windows are getting awfully tight Ergo, need to tighten up the design : as always !!! CONCERN / ISSUE METRIC / TOOL SPICE • DFM issues are not a & ~Gate Delays discontinuity STA • However there is a RC Extractors challenge with metrics ~Wire Delays etc. . • Area used to be a metric, but…. Simulators & ~Power • Yield is the obvious Vt selectors new metric but … • Designer has no way AREA ~Cost & Yield of designing for it ? ? without a way of quantifying it DESIGN CONSIDERATIONS

QUALCOMM Perspective Why go to next generation of Technology ? n Higher Performance n Ø New features n Cut-over as soon as possible Ø Existing (mostly) features n Ø Allow for de-bug, system integration n n Yield is Boss ! DFM very important Lower Cost Cut-over when cost is better Ø Allow for system re-qual time n n Die Size is Boss ! DFM desirable & optional DFM seems to be ‘the right thing to do’, but… Does it really make money for a Fabless COT House?

So, ARE there Economic Benefits in DFM ? n Don’t Really Know : 1. The commercial DFM space is fuzzy and confusing 2. The economic value of a DFM technology is confusing 3. The business case for DFM is unclear 4. The relative benefit of a DFM methodology is unclear n What we do know : Ø DFM is done to Optimize Costs and is hence a Business Decision Ø Any designer should be able to deal with the DFM trade offs

Need to Segment DFM Universe n Segregate DFM activities into 4 types need For this segment a 3 way relationship process Process Characterization design Models & Simulators Post GDS Transformation Pre GDS Transformation Test chip n Litho n Hot Spots n P&R n • Qualcomm role is CMP • Qualcomm DRC/MRC Measurements n that of a n role is that of an‘client’ Timing ‘champion’ or a ‘promoter’ n Data massage n Yield Principal differentiator is use mode and n Edge Massage n Synthesis • • Principal differentiator is n Validation. n Parametric n. n Architecture accuracy integration. Comps n …. . n Qualcomm has a different role with each ‘bucket’

Need to Monetize DFM Technical Value n DFM is Design to Optimize vs. Pass Go-No Go Checks Ø Function of process characteristics and maturity Ø Function of design technology and trade off vs. other variables Ø Function of product volume and ASP ramp EDA Tools $ Benefit Assessment DFM Design Decisions Yes/No Process maturity Process Design Kit Benefit of DFM Parameter 1 e. g. minimum die size - typically constant or slight ‘linear’ improvement with maturity Benefit of DFM Parameter 2 e. g. parametric yield or forbidden pitch compliance - typically high at ramp and saturates at maturity ?

Need a DFM Business Case n Business Model for Sharing Costs and Benefits Ø Foundry should reap the benefits for process improvements Ø Fabless design house should reap some benefit for DFM improvements 2 1 • With Die Business BENEFITS are mostly on the Foundry side • not entirely fabless gets larger capacity Wafer Business • With Wafer Business the BENEFITS are mostly with Fabless side • not entirely: foundry gets larger virtual capacity • The incremental COST of DFM is mostly on the Fabless side • not entirely: foundry does more characterization Die Business 3 4 Foundry • Fabless. The challenge is a Business Case for DFM in a Fabless House using a Die Priced Business Mode

Need a Metric for DFM Benefits n Yield or Project Cost is too Complicated Ø Retroactive direct measurements Ø Many compounding and confounding factors Ø Feedback loops long & often cloaked in economic factors n Need some Relative DFM “Score” Ø Arbitrary normalized number Ø Simple and non controversial Ø Not necessarily a direct measures of yield or cost • but intuitively related to those Ø Usable without a dedicated process-specific test chip n Perhaps Use Separate Scores, as makes sense ? Ø e. g. systematic vs. random vs. parametric phenomena

In fact Need Two DFM Metrics Match 2 kinds of costs n “Cost of Design” Design Ø measure the efficiency of implementing a given DFM optimization at various steps in the design flow • n e. g. routing, or (expensive) polishing, or (more expensive) OPC/RET “Cost of Si” Si Ø measure the net effectiveness of a given DFM optimization • e. g. percentage of redundant vias Cost of Design Cost of Si Parametric Integrity A X Shape Integrity B Y Thickness Integrity C Z Functional Integrity D w These metrics are important to Qualcomm but will not make or break a product Being a high volume shop, these are the key metrics that Qualcomm is very sensitive to

DFM Metrics for Cost of Design ? n Even un-weighted numbers e. g. frequency of occurrence of undesirable constructs ? would be useful as it would allow comparing a design Dimensions (e. g. at Design Rule vs. at DFM Guideline) and after some DFM before transformation Phenomenon (e. g. OPC unfriendly jog vs. notch vs. …. ) Ø ‘Bucketed’ in groups and Weighted by : • • Undesirable construct Dimension weighing factor A for x<DFM rule B for x>DFM rule Total Score n Or something like this ? Process weighing factor Weighted frequency High = H Count * A*H Low = L Count * B*L Type 1 = S

DFM Metrics for Cost of Si ? n e. g. frequency of occurrence of given features numbers Even un-weighted Ø ‘Bucketed’ in groups and Weighted by : • • would be useful as it would allow comparing a design Phenomenon (e. g. via vs. CA vs. …) before and after some DFM Layout configuration (e. g. bordered vs. borderless via…) transformation Process weighing factor Feature Weighted frequency Single via High = H Count * H Redundant via Low = L Count * L Critical area Med = M Count * M Total Score n Or something like this ? Type 2 = S

So, ARE there Economic Benefits in DFM ? n Can’t Really Know – and will not know until : 1. The DFM buzz is clarified • Need a clear definition of client-supplier relationships 2. Tool ROI is clarified • Need a way of estimating the benefits 3. DFM cost vs. benefit is clarified • Need ability to simulate and share benefit vs. time 4. Process data and ownership is clarified • n Need standard Design Kits What we do know : Ø We need DFM Score metrics Ø We need Process Design Kits

Are There Economic Benefits in DFM —