The overwhelming presence of microelectronics in our lives calls forthe development of new chips. The most innovative circuits integrateelectronic, mechanical, fluid dynamic and other functions. Hence,designers must have multidisciplinary backgrounds and must exercisecreativity and lateral thinking.
The microelectronics market is experiencing rapid growth. Shortpositive and negative cycles come and go, but the long-term trend isclear: The total value of semiconductor devices consumed globally willcontinue to increase.
The reason is simple: Chips serve as engines of innovation acrossdifferent industrial sectors. Technological milestones throughouthistory – including the large mainframe computers of the 1970s and therecent “convergent” systems that integrate calculation, communicationsand multimedia functions in a single device – have received an enormousboost from the progress of microelectronics, which has in turnpropelled the growth of the chip market.
|Figure1: The description of technological progress based on Moore's law isfar from perfect, as the number of transistors on a chip doubles every24 months|
Moore and beyond
Many believe that the growth of microelectronics follows Moore's law,which states that the number of transistors in a semiconductor doublesevery 18 months. However, the law's description of technologicalprogress is far from perfect, as the number of transistors on a chipactually doubles every 24 months (Figure1, above ).
Meanwhile, increasingly compact integrated systems plus the growingnumber of active elements on devices translate to greater powerconsumption. This is clearly at odds with the need for modernelectronic applications to operate longer on microscopic batteries.
|Figure2: If technology continues to advance according to Moore's law, deviceswill soon have a consumed energy density similar to that of a nuclearreactor.|
Intel experts have calculated that if technology continues toadvance according to Moore's law, we will soon have devices with aconsumed energy density similar to that of a nuclear reactor or eventhe surface of the sun (Figure 2, above ).
But this is not the only reason why Moore's law's description of theroad to the future falls short. The law is based on the assumption thatthere will be continuous evolution of lithographic techniques forsemiconductors, with consequent decrease in the size of basiccomponents and the capacity to place more transistors into the samesilicon surface.
The technological road map involves a mechanical evolution. Theincrease in number of transistors on a chip allows for more chipfunctions, which consequently raises power consumption.
Increasing chip function is useful especially for calculationapplications, but the real world is not made of calculations alone. Theheart of any system behaves like a human brain: it manages and performscalculations.
|Figure3: In a system that is efficiently integrated into its surroundingenvironment, the need to interact with the outside environment growsexponentially.|
However, having a brain is not enough – you need sensors to analyzeexternal reality and actuators to interact with the chip. When you needto process analog signals, generate power to drive actuators andproduce high-volume sound or music, reducing silicon geometries won'twork anymore. Traditional CMOS also starts to show its limits.
Electronic sensors and actuators need power technologies or radiofrequencies to communicate remotely, or fluidics to analyze and managefluids. These are areas in which progress cannot be dictated by Moore's law because it is notpossible to set a nearly automatic roadmap.
|Figure4: Elements whose development is dictated by Moore's law must coexistwith circuit blocks.|
In a system that is efficiently integrated into its surroundingenvironment, the importance of computing power increases, while theneed to interact with the outside environment grows exponentially.
Elements whose development is dictated by Moore's law must coexistwith circuit blocks, which are “more-than-Moore” and whose developmentdoes not depend on the almost mechanical progress of lithographicprocesses.
The development of such circuit blocks results from a designer'scapacity to invent and innovate, to apply “lateral thinking ” using consolidatedtechnologies, and to come up with solutions that tackle unusualapplications (Figure 4 above ).
Electronic progress thus stems from one's capacity to innovate andapply lateral thinking. Designers can identify and implement “clusters”of original inventions, using old, consolidated technologies, evenmaking major or minor changes to meet specific requirements.
For example, in the health service sector, improved knowledge ofgenome and DNA mapping combined with electronics, fluidics andmicromechanical applications integrated on silicon could give rise to a”cluster” of inventions that can save or improve the quality of life.In the convergence market, new electronic circuits must generate clearimages and crisp, high-volume sound by combining analog functions andcomputing power.
Microelectromechanical systems (MEMS ) integrate silicon to measure physical quantities such as acceleration,pressure or movement, and process the relevant electrical signals intoa single package.
Current applications of MEMS include triaxial accelerometers forNintendo's latest gaming console, safety devices for cars and hard-diskheads in PCs. The triaxial accelerometer in Nintendo's gamingcontroller detects the movement and angle of the hand and arm, enablingthe player to wield the controller like a sword or swing it like atennis racket.
In cars, accelerometers act as safety devices that detect imminentcollisions or excessive rolls that precede overturning. Fitted intoPCs, accelerometers can also detect the fall of a laptop onto thefloor. In this case, the hard disk heads are parked in a safe positionto protect valuable stored data.
|Figure5: A MEMS component can replace cellphone microphones, thus simplifyingassembly and reducing costs.|
A MEMS component can be used to replace cellphone microphones, thussimplifying assembly and reducing costs (Figure 5, above ).
All it needs to do is measure pressure changes and transform theminto electrical signals. MEMS technology also enables extremely compactmass storage, specifically through the use of very thin sheets ofmaterial in which the sequence of bits is represented by a set ofmicroholes.
This application allows tens of gigabytes of memory to be integratedinto a cellphone. Micromotors will need to be built to “read” themicroholes with molecular or even atomic precision. Siliconmanufacturers are not panicking though. Some examples of these newtechnologies are already operating in the most advanced laboratories (Figure 6, below) .
|Figure6: IBM's Millipede technology has a silicon tip with a radius of only10nm.|
A device that can do digital calculations and fluid management mayalso be used for DNA analysis. ST has created an integrated chemistrylaboratory on silicon. While it can be easily explained, itsimplementation is a bit complicated. A drop of organic material isplaced on a chip. The DNA is “amplified” then “recognized” using anoptical system. This device can rapidly diagnose diseases by analyzingthe DNA of pathogens.
It is a low-cost “disposable” system with almost immediate responsetimes, particularly useful at airports and seaports, for detectingcarriers of dangerous diseases such as bird flu (Figure 7, below ).
|Figure7: This lab-on-chip device can rapidly diagnose diseases by analyzingthe DNA of pathogens.|
Road map to creativity
Today's electronic design calls for lateral thinking. This may simplymean putting several silicon chips into a single package, rather thanincreasing the number of functions integrated into a single chip.Different chips may be made using different technologies optimized forspecific functions. Currently, design teams are finding ways to pile upto eight chips in a single package.
The neverending race towards ever smaller submicrometric andnanometric geometries will not decide the future of technology.
Identifying new applications for consolidated technologies andreliable competitive manufacturing techniques as well as theintegration of such fields as medicine, pharmaceutics, biology andelectronics, will pave the way for technologies that ultimately improvethe quality of human life.