Motorola adds more zip to its semiconductors

Published 9:00 pm Tuesday, September 4, 2001

Associated Press

NEW YORK — Motorola Inc. says it has developed a semiconductor that runs 35 times faster than today’s models, an innovation it hopes will lead to faster, smaller and cheaper cell phones, computers and telecommunications equipment.

While praising the company’s innovative solution, scientists remained cautious about predicting how soon the market might see new devices based on the technology.

Motorola says it has solved a 30-year-old problem of creating a semiconductor that combines the durability and economy of silicon with the high speed of crystal compounds used in lasers and fiber optic applications.

Its scientists did so by layering gallium arsenide, a fast but brittle semiconductor, onto silicon by way of a spongy middle, which binds the two and protects the coating.

"It’s a monumental change in the constraints on the construction of semiconductor systems," said Dennis Roberson, chief technology officer of Motorola. "We’ve opened the door on a whole new world."

The new wafers will be licensed next year, but the company doesn’t expect to see products on the market for another two years. Motorola has applied for 270 patents for the materials and production process of the semiconductor, which it says runs at 70 gigahertz instead of the current 2 Ghz, the speed of the fastest processors in personal computers.

While silicon has been the workhorse of the electronics industry, it is a relatively slow transmitter of signals. Electrons zip much faster through crystals of gallium arsenide and indium phosphide, which are also good transmitters of light.

Cell phones and other devices now use separate semiconductors of each material.

At Motorola’s Physical Sciences Research Labs in Tempe, Ariz., Jamal Ramdani saw that placing a soft layer of strontium titanate between the two materials would cushion the delicate coating. This would make it possible to grow the gallium arsenide crystal directly on a silicon wafer, integrating the two compounds.

"This brings a way of drastically lowering the price of high-performance compound semiconductor devices," says Darrell Schlom, an associate professor of materials science and engineering at Penn State University, who spent a month this summer at Motorola’s lab evaluating the new semiconductors.

"If it works, it could bring technologies like radar only affordable to the military to the consumer, but there are a lot of things that sound really good in the lab that never quite make it to the shelves."

Motorola says it has already made power amplifiers from the integrated semiconductors and has tested them in its cell phones.

But integration requires compromises, which could lessen the optical effects of a pure gallium arsenide crystal, notes Subramanian Iyer, a manager at IBM’s Microelectronics Division.

Iyer thinks that the current model, using two separate chips packaged together, "gives the best of both worlds at a reasonable costs, since you lose some capability when you try to integrate everything."

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