Chiplets are a new level of micro manufacturing
Under a microscope, four slivers of silicon – electronic circuits called chiplets – perform an elaborate, jerky dance as if controlled by a hidden puppet master. Then on command, they all settle with pinpoint accuracy, precisely touching a pattern of circuit wires, each at just the right point of contact.
The technology, on display at Xerox’s Palo Alto Research Center, or PARC, is part of a new system for making electronics, one that takes advantage of a Xerox invention from the 1970s: the laser printer.
If perfected, it could lead to desktop manufacturing plants that “print” the circuitry for a wide array of electronic devices – flexible smartphones that won’t break when you sit on them; a supple, pressure-sensitive skin for a new breed of robot hands; smart-sensing medical bandages that could capture health data and then be thrown away.
Today’s chips are made on large wafers that hold hundreds of fingernail-sized dies, each with the same electronic circuit. The wafers are cut into individual dies and packaged separately, only to be reassembled on printed circuit boards, which may each hold dozens or hundreds of chips.
The PARC researchers have a very different model in mind. They have designed a laser-printer-like machine that will precisely place tens or even hundreds of thousands of chiplets, each no larger than a grain of sand, on a surface in exactly the right location and in the right orientation.
The chiplets can be both microprocessors and computer memory as well as the other circuits needed to create complete computers. They can also be analogue devices known as microelectromechanical systems, or MEMS, that perform tasks like sensing heat, pressure or motion.
The new manufacturing system the PARC researchers envision could be used to build custom computers one at a time, or as part of a 3-D printing system that makes smart objects with computing woven right into them.
The technology is still in the future. The researchers are years from simultaneously placing tens or hundreds of thousands of circuits accurately in a fraction of a second. And they acknowledge that this would be only the first step in designing a commercially viable system.
Still, if the PARC researchers are successful, they will have thrown out 50 years of Silicon Valley conventional wisdom.
A related but simpler technology was pioneered by Alien Technology, a maker of RFID tags in Silicon Valley. Called Fluidic Self Assembly, it is based on suspending small integrated circuits called “nanoblocks” in a fluid and then flowing them over a surface where they drop into tiny holes of corresponding shapes.
Both approaches reverse a five-decade long tradition of making computers faster and more powerful by doubling every two years the number of transistors squeezed onto fingernail-sized computer chips.
The emerging printing technology poses a heretical idea: Rather than squeezing more transistors into the same small space, why not smear the transistors across a much larger surface?
Moreover, the research could have tremendous economic consequences – feeding the emergence of a new digital era in manufacturing, much as laser printing transformed publishing three decades ago.
By replacing the circuit boards now assembled in factories, the technology would vastly compress a supply chain that spans the globe and employs hundreds of thousands of workers.
It is one of a variety of technologies related to 3-D printers, which have captured the public’s imagination, raising the spectre of homemade manufacturing of everything from tools to guns.
“Digital fabrication will allow individuals to design and produce tangible objects on demand, wherever and whenever they need them,” Neil Gershenfeld, a physicist who directs the Center for Bits and Atoms at MIT, wrote in December in the journal Foreign Affairs.
While there has already been an explosion in 3-D printing of solid and mechanical objects both for prototyping and increasingly for small production runs, PARC’s scientists believe that there will also ultimately be an ensemble of manufacturing technologies that seamlessly blend microelectronics with mechanical components.
“You can print mechanical objects, but a lot of things in the world today are more than mechanical,” said Stephen Hoover, PARC’s chief executive. “A lot of the opportunities we’re going to find in the ‘Internet of things’ are going to be about how to embed intelligence at very low cost in a distributed way into the world.”
The new manufacturing system the PARC researchers envision would allow easier customisation. For example, just as today software customises computers for each purpose, computers in the future could be individually shaped for each system they were added to. Or in the future the computer could just be another part, to be added to the component inventory of a 3-D printing system.
Eugene Chow is an electrical engineer who leads the PARC team that has designed the new technology that they have dubbed “Xerographic micro-assembly.” The technology breaks silicon wafers into tens of thousands of chiplets, bottles them as “ink” and then “prints” them, much as a Xerox laser printer puts toner on paper, he said.
The PARC technology is based on the ability to use computing and an array of electrodes that generate microscopic electrical fields to control the precise placement of tiny electronic circuits – not just in the correct position, but with the proper orientation as well. “It’s a crazy new revolutionary tool,” Chow said.
Already, more than half a dozen different printing techniques, from inkjet to gravure to offset printing, have been used to make electronic circuits – a business that was estimated at $9.4 billion last year.