IBM taking Moore's Law by the horns

Moore's Law, an observation of Intel Corp. (intc) co-founder Gordon Moore, states that the number of transistors in a processor will double every 24 months. Despite falling under scrutiny from time to time, it continues to accurately reflect the progression of chip technology and become associated with increases in processor performance and complexity. Moore's Law in recent years has shortened to reflect a doubling of transistor count and performance every 18 months.

IBM's latest breakthrough, a new chip transistor design known as V-Groove, will allow the company to stay ahead of the curve of Moore's Law 15 to 20 years in the future, should it find its way into production.

V-Groove transistors are capable of scaling to channel lengths of 10 nanometers, or lengths of 0.01 micron and below.

Channel length represents the distance electricity needs to travel through a transistor; shorter transistors lessen the distance traveled, delivering greater performance. Right now, IBM (ibm), and the chip industry as a whole, is at 180 nanometers, or 0.18 micron. It had been widely believed that 20 to 25 nanometers were a hard stop.

"Using this simple technique, we can get channels as small as 10 nanometers or smaller," said Phaedon Avouris, manager of nanometer-scale science at IBM Research.

IBM says its V-Groove technique improves on current photolithography manufacturing techniques, which project an image of a transistor onto a chip, then physically remove excess silicon. V-Groove, in addition to lithography techniques, uses chemicals to create an anisotropic chemical reaction. That reaction burns away silicon faster downward than side-to-side, creating the namesake V-Groove channel. Channels, when produced using this technique, are much finer -- and therefore help eliminate electrical cross talk, otherwise known as the short-channel effect.

The short-channel effect -- which causes electrical interference between transistors located too close together -- had been the barrier to breaking the 20-nanometer mark. Normally, transistors switch on and off rapidly. The short-channel effect prevents them from switching off. V-Groove reduces short-channel effects, allowing normally functioning transistors to be built on this small scale.

With help from university research partners MIT and UCLA, IBM has been able to manufacture test transistors using V-Groove. It is now moving to create test chips using the technology. IBM officials say the experiment proves that it is possible to build chips with channel lengths smaller than previously thought possible. At the same time it proves Moore's Law is alive and well.

"Overall, we are very optimistic. This is a way of making a device to study transistors on a very small scale," Avouris said. "We are not looking for production. We are looking for a meaningful discussion of the limits of a small device. We'll leave it up to the engineers to discover the best way to put this into production."

IBM won't stop with V-Groove. The company is also exploring changes in materials it uses to manufacture chips.

IBM's next step is research into developing a method of putting the technology into mass production. It would be some time, about 15 years, before the V-Groove, or a similar design, would be used to manufacture chips en masse.

IBM Research, for example, is experimenting with the use of carbon nanotubes, structures made of rolled sheets of carbon hexagons. The nanotubes, in one example, could be made into interconnects between transistors.

The good news is that new discoveries in materials and manufacturing techniques, such as IBM's V-Groove, should sustain Moore's Law longer than previously thought, ensuring its extension for some 20 to 25 years. Moore's Law, at the same time, should stay true to its roots of accurately reflecting transistor counts.

Despite the breakthroughs that will carry Moore's Law -- and chip performance -- forward for several more years, IBM researchers say that Moore's Law may be losing its relevance as an accurate measure of performance.

Researchers say the microprocessor industry is entering an age where raw performance and simply doubling transistor counts every 18 or 24 months will no longer deliver functionality needed for applications in Internet or other areas, such as communications networks.

IBM (ibm) Essentially, IBM researchers say, Moore's Law has no ability to predict what features will be needed for future processors.

"My observation is that we're entering an era where Moore's Law is a less valuable tool to tell you where to go next," said Russell Lange, IBM fellow and chief technologist of IBM's Microelectronics Division.

Doubling transistor counts "certainly helps improve technology ... but just merely doing that is not nearly enough these days," Lange said.

"The value proposition is moving out into the Net and bandwidth and changing in many ways," he said. "Certain customers might not need clock speed. They might, for example, want more reliable memory technology."

For many consumers, the question of relevance may ring true. Right now, there is little need to increase performance, as a 500MHz Celeron or Duron chip can run today's desktop applications quite well, never mind a 1GHz or 1.1GHz chip. Taking the argument one step further, for those who spend time on the Internet regularly, it's more important to increase the bandwidth of the connection than to increase the clock speed of a PC processor.

However, chip makers aren't going to take that as permission to stand still. The demand for performance is still very much alive in servers and other infrastructure. This equipment, powered by microprocessors, provide network bandwidth, therefore contributing directly to network performance.

In addition, IBM and Intel agree that, especially with faster Internet connections, software will catch up to and exceed the capabilities of today's desktop processors, requiring more performance there as well. The only variable in this equation, they say, is time.

Despite the changes IBM is seeing, the company is racing ahead with its research to develop faster chips. However, IBM researchers say they are also looking at ways to make chips that are more customized for performing the work that needs to be done.

"It isn't just about scaling anymore, where Moore's Law calls for chips to become smaller and faster. It's just not useful to do that," Lange said. "We're spending a lot more time looking ... looking at other design elements."

To that end, IBM is researching new ways of solving processor-to-memory constructions with new kinds of memory structures. IBM is also working with new kinds of chip packaging.

"We've been experimenting with connecting a memory chip with a logic chip," Lange said.

Grafting the two together would increase performance and lower cost. In other applications, two complementary chips, such as a radio chip and a digital signal processor, could be sandwiched together. This direct connection, by itself, would increase performance by eliminating the need for data to flow over a bus.

Meanwhile, IBM has begun putting into production a number of new technologies that it says have the potential to significantly boost chip performance over the short term.

Most recently, IBM added PowerPC processors with SOI (silicon on insulator) technology and copper interconnects to its AS/400 line of servers. The SOI technology increases transistor performance by reducing parasitic capacitance -- a performance hit caused when electrical current is absorbed by the silicon substrate that a transistor rests on. Thanks to the insulator, the chip can push greater amounts of current, which increases performance. Or, using an SOI, a chip can be tuned for lower power, making it better for use in portable electronics.

IBM also plans to boost performance of its RS/6000 S80 servers by adding new PowerPC processors with SOI technology to this family this fall.

The company has announced a number of other new technologies. Many of these new technologies will be resident in IBM's Power4 chip. The chip, which features two 1GHz-plus processor cores on a single chip (a single-chip dual processor), will debut next year in high-end IBM servers.

IBM recently brought up Linux and its AIX operating system on the chip.

These technologies, now in production, will carry IBM forward, while its research division tackles the bigger problems and works to deliver new technology, such as V-Groove, into production.

"A lot of people worry about the end of the industry; how long can this keep going?" Lange said. "Usually, what folks underestimate is how energetic scientists and engineers are when it comes to overcoming hard limits."