Technology beats transistor heat

Intel has identified new materials to replace those that have been used to manufacture chips for more than 30 years.

This is a significant accomplishment as the industry races to reduce electrical current leakage in transistors - a growing problem for chip manufacturers as more and more transistors are packed onto tiny pieces of silicon.

Intel researchers have developed record-setting, high-performance transistors using a new material, called high-k, for the 'gate dielectric' and new metal materials for the transistor 'gate'.

The gate turns the transistor on and off and the gate dielectric is an insulator underneath it that controls the flow of current. Together, the gate and gate dielectric materials help reduce current leakage that leads to reduced battery power and generates unwanted heat.

Intel said the new high-k material reduces leakage by more than 100 times over the silicon dioxide used for the past three decades.

The industry has been searching for new transistor gate materials for many years, but technical difficulties have impeded practical implementation.

"This is the first convincing demonstration that new gate materials will enable transistors to perform better, while overcoming the fundamental limits of the silicon dioxide gate dielectric material that has served the industry for more than three decades," said Sunlin Chou, Intel senior vice president and general manager of the Technology and Manufacturing Group.

"Intel will use this advancement along with other innovations, such as strained silicon and tri-gate transistors, to extend transistor scaling and Moore's Law."

According to Moore's Law, the number of transistors on a chip roughly doubles every two years, resulting in more features, increased performance and decreased cost per transistor.

To maintain this pace of innovation, transistors must continue to shrink to ever-smaller sizes. However, using current materials, the ability to shrink transistors is reaching fundamental limits because of increased power and heat issues that develop as feature sizes reach atomic levels.

As a result, implementing new materials and innovative transistor structures is imperative to the future of Moore's Law and the economics of the information age.

The high-k and metal gate solution

All transistors have an insulator material, called a gate-dielectric that is critical to their operation. For the last 30 years, silicon dioxide has served as the material of choice for this key transistor component because of its manufacturability and its ability to deliver continued transistor performance improvements at smaller sizes.

Intel has shrunk the silicon dioxide gate dielectric to sizes down to 1.2 nm thick, which is equal to only five atomic layers.

As the silicon dioxide material gets thinner, electric current leakage through the gate dielectric increases and leads to wasted current and unnecessary heat.

To keep electrons flowing in the proper location and solve this critical issue, Intel plans to replace the current material with a thicker high-k material in the gate dielectric, significantly reducing current leakage.

The second part of the solution is the development of a metal gate material, since the high-k gate dielectric is not compatible with today's transistor gate.

The combination of the high-k gate dielectric with the metal gate enables a drastic reduction in current leakage while maintaining very high transistor performance, making it possible to drive Moore's Law and technology innovation well into the next decade.

Intel believes that these new discoveries can be integrated into an economical, high-volume manufacturing process and is now moving this transistor research into the development phase.

Transistors with these new materials are an option targeted to be integrated into future processors as early as 2007, as part of the company's 45 nm manufacturing process.