Chip Making On A RollChip Making On A Roll

Roll-to-roll printing revolutionized the newspaper industry more than a century ago. Now, Rolltronics wants to turn chip fabrication on its ear using a roll-to-roll system. The Menlo Park, Calif., company has partnered with Iowa Thin Film Technologies in Ames, Iowa, to create flexible sheets of silicon transistors that can dramatically reduce the cost and waste involved in chip production, says Glenn Sanders, Rolltronics' VP of business development and IT.

In the new process, a quarter-mile-long sheet of flexible polymer is unrolled from one spool, covered with silicon patterns, and rolled onto another spool. The first spool is about 12 inches wide--the width of the largest silicon wafers. That's a much more cost-efficient way to make low-density chips than factories now use, Sanders says, because current techniques cater to high-density microprocessors. The roll-to-roll method also uses many recyclable materials and fewer toxic solvents and cleaners than conventional semiconductor production.

While companies such as Bell Labs and IBM have developed flexible transistors, Sanders says, there's a significant distinction: Rolltronics uses silicon, while the others use plastic. "We decided to focus on silicon from the very beginning, because plastic will never compare when it comes to [transistor-to-transistor] switching speed and how much current it can handle," he says.

Rolltronics hopes to ship products based on the roll-to-roll technology within two years. One possibility Sanders envisions is a smart card that could display a bank customer's account balance in real time. Another: A powerful, lightweight E-book-like reading device an eighth of an inch thick, with a resolution that matches a laser printer and low power requirements that let it run on a thin-film battery for weeks or months.

Sanders also anticipates that roll-to-roll chips will be used in cheaper desktop displays, flexible electronic paper, radio-frequency identification tags, digital X-ray detector panels, and biometric sensors, among other products.