Monday, November 26, 2007

Printing Cheap Chips

Kovio's system for printing inorganic transistors could lead to large-area displays and cheap smart cards.

By Kevin Bullis

Printing processors: Printed transistors such as this one could bring microchips to everyday objects. Different inks are used for various parts of the transistor, which include the electrical contacts, the source and drain (top and bottom), and the controlling gate. Credit: Kovio

After years in "stealth mode," a company founded to commercialize technology originally developed at MIT's Media Lab has announced a new process for printing transistors for memory and logic chips, as well as analog devices for radio. Since the technology uses commercial printing equipment such as inkjet printers, it could be a cheap and easy way to make high-performance microchips.

The first products made by the company, Sunnyvale, CA-based Kovio, will likely be disposable smart cards for public transportation, which could be available by the end of next year. Eventually, the technology could help enable a range of applications, including wall-sized displays.

Kovio is one of a number of companies developing ultracheap alternatives to conventional microchips by replacing conventional photolithography methods with printing techniques. Such processes produce larger transistors than conventional chip-making methods--a printed chip might have a thousand transistors, rather than hundreds of millions--and won't likely compete with the microchips used in computing or consumer electronics. But because printed electronics are cheap to make, they could lead to the use of microchips in a large range of common objects, as well as large displays that cover, for example, an entire wall.

What sets Kovio apart from most printed electronics companies is that it uses inorganic semiconducting materials, such as silicon, rather than organic materials such as conducting polymers. Although they cost a bit more, the inorganic transistors have 100 to 1,000 times better performance than organic transistors, says Vivek Subramanian, who works on printed organic electronics at the University of California, Berkeley and is a technical advisor to Kovio. Organic materials are cheaper and can be easier to work with, but inorganic materials, and the processing techniques Kovio has developed, make it possible, for example, to produce radio devices that switch at speeds fast enough to meet current RFID standards.

Amir Mashkoori, Kovio's CEO, says the company can print memory and energy-efficient CMOS logic devices, as well as analog circuitry for radios, to make RFID tags that cost less than a nickel. To do this, they've developed a variety of inks, including nanocrystalline metals for electrodes and connections between devices, doped silicon semiconductors, and insulating materials. Kovio's process makes use of several types of commercial printers, including inkjet models. The printing is followed by a curing process. Kovio estimates that its system requires just 5 percent of the materials and a quarter of the electrical power used in conventional chip-making processes, with equipment that costs a third as much.

Within five years, the cost for some applications could fall to just a penny a piece, Mashkoori says--cheap enough for stores to replace barcodes with RFID tags. Such tags could make tracking inventory much easier. Eventually, consumers may be able to read the tags with their cell phones to confirm that a product complies with their dietary restrictions or to keep a tally of the cost of items in their basket. Items could be paid for by walking past a reader and accepting the charges.