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CMOS VLSI Design

CMOS VLSI Design. Technology, Business Model and Future Trends. Plenty of Room at the bottom??. Currently at 45 nm process node and soon to be on 28 nm Lithography was seen to be a major obstacle (dealt with using Immersion or X/EUV) Moore’s Law still holding but for how long?

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CMOS VLSI Design

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  1. CMOS VLSI Design Technology, Business Model and Future Trends

  2. Plenty of Room at the bottom?? • Currently at 45 nm process node and soon to be on 28 nm • Lithography was seen to be a major obstacle (dealt with using Immersion or X/EUV) • Moore’s Law still holding but for how long? • Transistors on die doubling and so is the Fab cost (Standing at close to 5bn for latest tech)

  3. Materials Innovations • STI (Shallow Trench Isolation), CMP (Chemical Mechanical Polishing) and other process enhancements are now part of all manufacturing • Cu Interconnects replacing Al • Low-K dielectric for successive metalization • High-K Oxide for the Gate • Metal Gate replacing Polysilicon

  4. What about Transistor? • Traditional CMOS structure being questioned • Tri-gate and other FINFET structures likely to be adopted going forward • Primary reason being Power (esp. Leakage Power) • Power density of a nuclear reactor in a server class microprocessor • Power coming ahead of feature size or cost

  5. Alternatives to Silicon?? • GaAs, SiC, InP and so on • How about nanotechnology? Carbon Nanotubes? • Silicon Ecosystem is hard to beat and drivers for such transition are not there. • Industry reluctant to move to 450 mm wafers (due to cost reasons) even though good enough rational exists for it.

  6. Design Process • Front End (Architecture, RTL Coding, Test Bench, Lint, CDC checks, Synthesis, DFT, STA, Power Estimation) • Back End (Floorplan, PowerPlan, Timing Constraints refinement, Placement, Optimization, Global Routing, CTS, Detailed Routing, Timing Closure and Physical Verification • ECO (Engineering Change Order)

  7. Skills Development • FPGA are great platform to learn and practice design skills but be fully aware that ASIC requires some extra work that is not exposed to designers in FPGA world • Majority of the design bugs are still functional bugs; despite increasing complexity of the CMOS technology • Any software engineer can write verilog (its almost like C anyways) until they hear about “CLOCK”

  8. Skills Development (Cont.) • PERL (If you have not heard of it, please google it right away if you ever plan to design chips) • Same for TCL • Some aspects of software development process are relevant to chips as well (Version Control, Build Process, Bug Tracking etc.) • Finally, knowledge of end-user application will make you better architects

  9. Design Tools • Hammer, Wrench and Pliers • EDA world inhabited by superb software engineers who like to create smart algorithms and innovative UI but they rarely design chips • No set of tools will let you build chips just using the tools alone; i.e. it is inevitable that you will need to build some custom scripts, tools to patch together a flow • With evolution of technology, some of the concerns like signal integrity or power grid design etc now require as much attention as gates

  10. Intellectual Property • Holy Grail of modern chip design is the assembling them like Lego bricks using pre-existing sub modules • In no chip has it worked that way, unless a particular IP has been used and built into working silicon already • Intellectual Property does not equal RTL code! • Despite all these problems, no SoC is ever built from scratch.

  11. Section II Business model

  12. End Markets • 3 Cs (Computers, Communications, and Consumer) • Industrial and Automations is also a significant users • Migration to CMOS for digital design as well as for other technologies like RF or Image Sensor • Mixed signal chips in wireless world • More and more applications are implemented using digital (Audio, Video, Motor Control, etc)

  13. Integrated Device Manufacturer • Chips, screws, boxes and software (IBM, DEC) • Today even design, manufacture and marketing of chips is rarely done by same company (Intel) • Fabless Model is well developed and has proven successful • EDA model is somewhat successful and IP business model is questionable

  14. ASIC vs FPGA • Number of design starts every year are shrinking, esp in recession • FPGAs are attractive alternative for any markets not requiring strict power, cost and size budgets • High volume markets still require custom ASICs • FPGAs are now able to meet fairly high performance requirements; networking gear is an ideal market for them

  15. Best of both worlds?? • How about programmable array on a custom ASIC • May be appropriate for some niche markets • The design starts are decreasing but the design teams needed to execute very large chips (afforded by more available transistors) on latest technology node requires large design teams

  16. GHz, now it really hurts! • Until the beginning of this decade there was an implicit GHz race among high-performance chip makers but soon the lesson was learned that even if technically feasible it is not the right way to performance • Multi-core is the new new thing, if you have not read any research from 20 yrs ago • In any case, mobile phone processors are not at 1 GHz and possibly 2 or 4 cores on the die

  17. Memory, IO and Usability • DDR, Flash • USB, PCI Express • Hot plugged, power managed and auto-configured IO • All IO technologies now serial (LVDS) instead of wide parallel CMOS • Still there are too many to choose from

  18. Semiconductor Market • 300bn per year • Majority of it is digital IC • IDMs still sell lot of standard parts like micro-controllers, memories etc but fabless is not becoming larger and larger part of the market • Eventually, standard parts will be needed for specialty markets like industrial, automotive, power, sensors, control etc but rest will be digital CMOS and very likely fabless

  19. Newer Markets or More Integration? • Health Care, Biomedical, Renewable Energy (Solar Cells etc.) • LCD, LED, OLED displays • Laser projectors • 3 Cs will remain significant users of standard CMOS digital semiconductor but may become commoditized • Innovations will be sector(application) specific

  20. EDA and IP • ARM is the only surviving IP company of significant size • Despite superficial similarities, Software business model does not transplant to chip design • EDA model is moderately successful, 3 bn EDA serving 300bn semiconductor industry • IP and Design Services model is not scalable

  21. Section III Future trends

  22. Reading Tea Leaves • There may be market for 5 computers world wide • Who will need a computer in their home? • Who can possibly need more that 640K of RAM? • Given such illustrious company, I am not shy to make a fool of myself

  23. Fabless is the future • It may even be present depending on who you ask • Need a way to spread risk • IDM model declining due to capital requirements • Fabless model may also face the same issues; hard to compete with dot coms for VC dollars • India has chance to catch up in terms of design skills once technology nodes stabilize

  24. Costs • Latest technology node fabs cost close to 5 bn • It can be trouble if utilization drops below 90% • 20 yrs ago DRAMs were the drivers of technology, then microprocessors and now flash memories • Digital CMOS IC development costs are also escalating, easily 20-30 mn for significant size SoC; implies high volume markets to be able to amortize the development costs

  25. Convergence is cool • Your laptop is your only computer • Tomorrow, your iPhone may be your only computer • Your computer is your media player, will it also be your set top box? • Your mobile phone is also your home phone • Voice or Video: everything is just an IP packet • Telco Switches or CISCO routers?

  26. Internet • Bubble that indeed changed the world • Broadband (wireless or wired) will be the only media-agnostic communication pipe to the consumer • Most people on the planet will first experience internet on their mobile and not computer • Roughly, every other person on the planet has a mobile

  27. Skip a grade • Developing countries like India can skip a few steps in technology migration • With china quickly climbing the value added food chain of technology development, latest technology will become affordable in developing world (Wireless, Media Players, Electric Cars) • Indian engineers and manufacturers can no longer live in splendid isolation

  28. To design, to make or to service? • India has sadly missed the boat on manufacturing semiconductors (even if 5 bnfab can erected, it is impossible to keep it fed) • Design Services: low margin, cyclical business that does not scale • Design aka fabless is fairly reliable business model (although comparatively costly) Costs can be mitigated by doing all engineering work in India

  29. Test and Assembly • There is an opportunity here • Lacking manufacturing capability is a bit disadvantage but english-speaking skilled work force is a plus • Maturing industry will fragment further and will look for cheaper destinations • If India can successfully create a fabless industry, it would match china’s manufacturing capability and will be complementary

  30. Questions • Fabless Semiconductor Association (recently changed name) • Latest scoop on tools: deepchip.com (John Cooley) • Eetimes.com, electronicnews.com • CMOS VLSI Design (Neil Weste) • Intel Technology Journal

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