IBM and allies find a way to make chips even tinier and faster




Chip designs two generations more advanced than today’s cutting-edge designs are now closer to reality as IBM announced Wednesday it’s built a test processor that makes computer circuitry significantly more powerful.

The test chip has working components, called transistors, but it is a research and development project rather than a finished product that can be built into a computing device like a laptop, server or smartphone. Nevertheless, it’s an important step extending Moore’s Law and its promise of steady progress in the computer industry.

The processor progress charted by Moore’s Law has shrunk computers from refrigerator-sized hulks to smartphones that fit in your pocket. But it’s getting harder to develop each new generation of chip technology, requiring years of materials research and manufacturing facilities costing in the vicinity of $10 billion. IBM’s work signals that it’ll be feasible to miniaturize chips further, helping to enable devices like powerful smartwatches or perhaps augmented-reality contact lenses.

“This is a welcome sign for the chip industry,” said Envisioneering analyst Richard Doherty. “You can count on at least two more turns of Moore’s Law benefits.”

Moore’s Law is named after Intel co-founder Gordon Moore, who 50 years ago noticed steady improvements in the number of transistors on a chip. Under Moore’s Law, that number doubles every two years, unlocking new computing power and making it economical to squeeze processors into ever-smaller devices.

IBM Research led development of the technology with allies including electronics giant Samsung and chip manufacturer GlobalFoundries at a State University of New York nanoscale engineering project in Albany, New York. The work is part of the Common Platform alliance designed to speed research and the transition to new manufacturing methods. As the costs of developing and building next-gen chips rise, such alliances let companies pool their resources to better keep up with industry leader Intel.

Even with allies, the work doesn’t come cheap. IBM last year pledged to spend $3 billion over five years on research to continue diminishing the scale of chip features.

Seven nanometers or bust

Today’s cutting-edge chips from Samsung and Intel are built with circuitry features measuring 14 nanometers, or 14 billionths of a meter. That’s extraordinarily small: 14nm is 7,000 times narrower than a human hair, or alternately, six times wider than a strand of DNA.

One generation out will be chips with 10nm features that will double the circuitry for a given area. Two generations out come 7nm chips, and that’s what IBM Research has demonstrated. For comparison, 7nm is less than three times the width of that 2.5nm DNA strand.

This comblike pattern on IBM Research's test chip shows the protruding "fins" in the foundational chip circuit elements called transistors.Enlarge Image
This comblike pattern on IBM Research’s test chip shows the protruding “fins” in the foundational chip circuit elements called transistors.IBM Research

“It’s a major step,” said Mukesh Khare, vice president of semiconductor technology at IBM Research. “We have been working on this technology for more than five years.”

IBM’s 10nm technology improved the power-performance ratio by 40 percent or 50 percent over today’s 14nm chips, meaning that a computer designer could either lower power consumption for better battery life or speed up software running on a computer. The 7nm design increases the power-performance ratio another 50 percent over the 10nm generation, Khare said.

IBM previously built its own chips, mostly for powerful servers that it sells to big businesses wanting track global inventory levels, find patterns in sales trends or host large-scale online services. In July, though, GlobalFoundries announced itcompleted its acquisition of IBM’s microelectronics business; IBM will pay GlobalFoundries to build its chips for the next 10 years.

Intel has led the industry in the development of new manufacturing processes, introducing a new generational “shrink” every two years. It’s not clear yet how Intel will move to 10nm and 7nm chips, though.

“Intel has said almost nothing publicly that’s concrete about 7nm development,” said Forrester analyst Richard Fichera. “It’s real hard to bet against Intel in the long run, but [IBM Research’s 7nm work] clearly says they have somebody breathing down the back of their neck.”

The road to 7nm

IBM Research and its allies employed a number of technologies to make its 7nm prototype real. Two big ones are a chemical compound called silicon germanium and an optical etching technology using extreme ultraviolet light.

Researchers hold a silicon wafer 300mm in diameter that houses dozens of test chips.
Researchers hold a silicon wafer 300mm in diameter that houses dozens of test chips.IBM Research

Computer chips are built on a disk-shaped substrate of silicon crystal called a wafer, but chipmakers have long fiddled with the wafer’s exact chemical composition. Doing so can mean better electrical properties for transistors, the tiny on-off switches that in their millions or billions make up a modern microchip. For IBM Research’s 7nm chips, adding a layer of silicon germanium makes the transistors switch on and off faster, Khare said. The chip can therefore process data faster, meaning there’s less of a delay to apply that Instagram photo filter or to draw that Starcraft spaceship on the screen.

The extreme ultraviolet light is used for the etching of circuitry patterns on the silicon wafer — a fundamental part of chip manufacturing. This etching process, called photolithography, shines light through a mask that has an extremely complicated arrangement of transparent and opaque areas. Where the light shines or doesn’t changes the composition of the wafer, which means different types of materials can be added removed to manufacture the three-dimensional transistors and interconnection circuitry.

Finger-painting with a boxing glove

Photolithography patterns have shrunk along with chip circuitry sizes, but for the last decade or so, chipmakers have used invisible ultraviolet light with a wavelength of 193nm. That’s remarkable, given that it’s something like detailed finger-painting with a boxing glove. But by using a succession of two or three specially created masks for each layer of a chip pattern, chipmakers can construct very small-scale features.

For the 7nm chips, IBM Research uses extreme ultraviolet light, with a wavelength of 13.5nm that permits much smaller features.

“It’s really hard,” Doherty said of the extreme ultraviolet (EUV) transition. “These invisible light waves are almost X-rays in wavelength! The optics are different, the masks, the materials — everything.”

The chip industry has been expecting extreme ultraviolet for years, though, and the transition pain will pay off with a lithography process that can support future chipmaking generations, too, Khare said.

“Scaling of semiconductor technology is getting harder and harder,” Khare said. “The business-as-usual conventional techniques do not apply.”