IBM takes chip manufacturing ‘au naturel’



The natural pattern-creating process that forms seashells, snowflakes, and enamel on teeth has been harnessed by IBM to form trillions of holes to create insulating vacuums around the miles of nanoscale wires packed next to each other inside each computer chip.


The IBM patented self-assembly process moves a nanotechnology manufacturing method that had shown promise in laboratories into a commercial manufacturing environment for the first time, providing the equivalent of two generations of Moore’s Law wiring performance improvements in a single step, using conventional manufacturing techniques.

This new form of insulation, commonly referred to as “airgaps” by scientists, is a misnomer, since the gaps are actually a vacuum, absent of air. The technique deployed by IBM causes a vacuum to form between the copper wires on a computer chip, allowing electrical signals to flow faster, while consuming less electrical power. The self-assembly process enables the nanoscale patterning required to form the gaps; this patterning is considerably smaller than current lithographic techniques can achieve.

A vacuum is believed to be the ultimate insulator for what is known as wiring capacitance, which occurs when two conductors-in this case, adjacent wires on a chip-sap or siphon electrical energy from one another, generating undesirable heat and slowing the speed at which data can move through a chip.

Until now, chip designers often were forced to fight capacitance issues by pushing ever more power through chips, creating other problems in the process. They have also used insulators with better insulating capability, but these insulators have become fragile as chip features get smaller and smaller, and their insulating properties do not compare to those of a vacuum.

The self-assembly process already has been integrated with IBM’s manufacturing line in East Fishkill, NY, and is expected to be fully incorporated in IBM’s manufacturing lines and used in chips in 2009. The chips will be used in the company’s server product lines and thereafter for chips it builds for other companies.

“This is the first time anyone has proven the ability to synthesize mass quantities of these self-assembled polymers and integrate them into an existing manufacturing process with great yield results,” says Dan Edelstein, IBM Fellow and chief scientist of the self-assembly airgap project. “By moving self-assembly from the lab to the fab, we are able to make chips that are smaller, faster, and consume less power than existing materials and design architectures allow.”

The secret of IBM’s breakthrough lies in how the IBM scientists moved the self-assembly process from the laboratory to a production environment in a way that can potentially yield millions of chips with consistent, high-performance results.

Today, chips are manufactured with copper wiring surrounded by an insulator, which involves using a mask to create circuit patterns by beaming light through the mask and later chemically removing the parts that are not needed. The new technique to make airgaps by self-assembly skips the masking and light-etching process. Instead, IBM scientists discovered the right mix of compounds, which they pour onto a silicon wafer with the wired chip patterns, then bake it.

This patented process provides the right environment for the compounds to assemble in a directed manner, creating trillions of uniform, nanoscale holes across an entire 300 mm wafer. These holes are just 20 nm in diameter, up to five times smaller than would be possible using today’s most advanced lithography technique. Once the holes are formed, the carbon silicate glass is removed, creating a vacuum between the wires-known as the airgap.

Self-assembly is a concept scientists around the world have been studying as a potential technique to create materials useful for building computer chips. The concept occurs in nature every day. The major difference is, while the processes that occur in nature are all unique, IBM has been able to direct the self-assembly process to form trillions of holes that are all similar.

The self-assembly process was jointly invented between IBM’s Almaden Research Center in San Jose, CA, and the T.J. Watson Research Center in Yorktown, NY. The technique was perfected for future commercial production at the College of Nanoscale Science and Engineering of the University at Albany, within the world-class Albany NanoTech facilities, a research and development site in Albany, NY, and at IBM’s Semiconductor Research and Development Center in East Fishkill, NY.