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Tiny Transistor Breaks Barrier For What Fits on Computer Chip

By Kathleen Scalise, Public Affairs
Posted December 1, 1999

Berkeley engineers have created a new type of semiconductor transistor so small that a single computer chip can hold 400 times more of the devices than ever before.

"It's a new world record," said Chenming Hu, professor of electrical engineering and computer sciences.

The development could lead to significantly faster and cheaper chip technology, he said.

Details of the prototype transistor, called "FinFET," will be presented for the first time on Dec. 7, by co-developer Xuejue Huang, a Berkeley graduate student, at the International Electronic Devices Meeting in Washington, D.C.

The breakthrough is due to a change in the design of the transistor "gate," or switch, that controls the flow of current in the electronic devices. Typically, this gate is a flat conductor that controls only one side of the passage through which current flows in a transistor. This design is limited because it cannot turn off the current flow when the gate is much shorter than its present length.

The new design, however, uses a fork-shaped prong that straddles both sides of the current channel. This improves control and reduces current leakage so that the gate, and thus the transistor, can be made much smaller.

"We can now control the channel from both sides," Hu said. "An analogy is to think of this channel like a vein. If you want to stop bleeding, you would pinch the vein from both sides. This would be much better than just pressing from one side."

The FinFET has a 18-nanometer-long gate, about the width of 100 atoms. It is not visible to the naked eye but can be viewed with a scanning electron microscope. Hu hopes to cut this length by half in future work.

"But what we've actually produced is already 10 times shorter than what industry is now using," he said.

Hu said the success of the electronics industry has been based on making transistors ever smaller for the last three decades. But, Hu said, the laws of physics eventually will limit what can be done unless a new transistor design, such as the Berkeley prototype, is adopted.

The prototype was successfully fabricated last July and shows good performance characteristics, Hu said. No patent has been taken on the device.

"We made the decision not to patent," Hu said. "We want the widest possible usage. We hope this becomes a mainstream transistor structure in the future."

Besides Hu and Huang, other collaborators on the project include Berkeley electrical engineering and computer science professors Tsu-Jae King and Jeffrey Bokor; Berkeley graduate students Wen-Chin Lee, Charles Kuo, Leland Chang, Jakub Kedzierski and Yang-Kyu Choi; Berkeley researchers Vivek Subramanian and Hideki Takeuchi; Erik Anderson of the Lawrence Berkeley National Laboratory; and Digh Hisamoto of the Hitachi Ltd. Central Research Laboratory in Tokyo.



December 1, 1999 - January 11, 2000 (Volume 28, Number 16)
Copyright 1999, The Regents of the University of California.
Produced and maintained by the
Office of Public Affairs at UC Berkeley.
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