Agere Systems, Caltech Scientists Develop Technique That Could Shrink Memory Chips in Cell Phones, Digital Cameras.

Business Editors/Hi Tech Writers

SAN FRANCISCO--(BUSINESS WIRE)--Dec. 13, 2000

Researchers at Agere Systems, formerly known as the Microelectronics Group of Lucent Technologies (NYSE:LU), and the California Institute of Technology have developed a technique that could make memory chips for cellular phones and digital cameras smaller, less expensive and more reliable.

The research development, announced today at the International Electron Devices Meeting, applies to a type of memory called "flash" memory - which continues to store information even when the devices are turned off. This information could include personal phone directories in a cellular phone or the pictures captured by a digital camera. In the typical cellular phone, there are 16 to 32 million bits of data stored on a silicon flash memory chip. Each bit of data is stored in a part of the flash memory chip called a "cell."

Unlike traditional silicon chips, which continue to double in transistor density every 18 months as dictated by Moore's Law, the design requirements of flash memory present more challenges for continued reduction in size.

"The concept of today's conventional flash memory cell is very similar to a bathtub," said Agere Systems researcher Jan De Blauwe. "The electrical charge that represents the bit of data typically remains in the tub, but if the tub springs a leak, that charge is lost. And as we try to shrink the size of these conventional tublike cells to make the memory chip smaller, the chance that they'll develop leaks increases. Solutions to this problem exist, but these solutions are increasingly expensive to fabricate, especially since they require the memory cells to operate at higher voltages than today's mainstream chip technology."

To overcome the potential leakage problem, De Blauwe and his Agere Systems colleagues, along with Harry A. Atwater and Richard Flagan and their students at Caltech, developed a method to break up each memory cell into 20,000 to 40,000 smaller cells, or "buckets." Therefore, even if several of the buckets spring a leak, the vast majority of the charge is not lost and the bit of data stored in the memory cell is retained.

Using an aerosol technique developed at Caltech, the researchers formed the buckets by spraying silicon nanocrystals through a bath of high-temperature oxygen gas. The end result was buckets comprised of silicon on the inside with a silicon dioxide outer shell. The silicon nanocrystal buckets store the electrical charge, whereas the silicon dioxide shell makes the buckets more leak-proof.

"As compared to conventional flash memories, these silicon nanocrystal memories are easier to fabricate and intrinsically more leak-proof, which could result in lower fabrication costs and lower operating voltages," said De Blauwe.

"We created a hailstorm of silicon nanocrystals, but in this case, the hail was 5 to 10 billionths of a meter, or nanometers, in diameter," said Caltech graduate researcher Michele Ostraat. "The real challenge was getting an even distribution of silicon nanocrystals."

The aerosol approach has several advantages over conventional lithographic techniques used to make today's flash memory cells. Because it requires fewer steps, it is both less expensive and requires less time. In addition, the aerosol approach will allow researchers to continue making smaller and smaller devices. Currently, because conventional cells, or bathtubs, are becoming more and more difficult to make leak-proof, it is unlikely that their size, and more importantly, their operating voltages, will reduce much further.

"As the insulating layer on these electrical devices become thinner and thinner, they always are more vulnerable to leaks," said Agere Systems researcher Martin Green.

So far, the researchers have created extremely robust flash memory cells. For instance, they have charged and dissipated a single cell one million cycles without significant degradation, whereas 10,000 cycles is considered good. While these research results are promising, it is premature to predict if or when the technology will be commercially implemented.

Agere Systems Inc., formerly known as the Microelectronics Group of Lucent Technologies, is the world leader in semiconductors for communications applications. Lucent has announced it intends to spin off Agere Systems as an independent company. Agere Systems offers integrated optoelectronics and integrated circuits solutions to help customers reduce the time and expense of developing new communications equipment. It also provides wireless computer networking solutions through its ORiNOCO(TM) product line. More information about Agere Systems is available from its Web site at http://www.agere.com.

This release may contain forward-looking statements based on current information available to the company as of the date hereof that involve risks and uncertainties. The company's actual results could differ materially from those results stated or implied by such forward-looking statements due to risks and uncertainties. These risks and uncertainties include, but are not limited to, completion of the spin-off from Lucent Technologies Inc., price and product competition, keeping pace with technological change, dependence on new product development, reliance on major customers and suppliers, customer demand for our products and services, availability of manufacturing capacity, components and materials, control of costs and expenses, general industry and market conditions and growth rates and general domestic and international economic conditions including interest rate and currency exchange rate fluctuations.

Note to editors -- illustration available upon request