Intel will change two materials used in the manufacturing of its chips in order to improve performance and reduce power leakage as its transistors shrink over the next four or five years.
When Intel rolls out its 45-nanometre process technology, scheduled for 2007, it will substitute a "high-k" material for the silicon dioxide gate dielectric currently used in making transistors for its processors. The company will also use metal gate electrodes in place of the polysilicon gate electrodes on its current transistors.
"A transistor is basically a sophisticated switch, and we're changing two small elements to prevent current leakage," said Ken David, director of components research for Intel's technology and manufacturing group, during a conference call.
The silicon dioxide gate dielectric in Intel's transistors is used to keep the electric field applied to the switching mechanism, or gate electrode, of a transistor from mixing with the current flowing through the transistor, said Dean McCarron, principal analyst with Mercury Research.
As semiconductor companies have continued to manufacture smaller and faster transistors, the width of that gate dielectric has decreased to the point where electric current can leak from the channel through which it flows out onto the surface of the chip, causing heat to dissipate from the chip, David said.
After five years of research aimed at solving the leakage problem, Intel chose a material with a high "k" value that does just as good a job as silicon dioxide in separating the electrical fields, but is thick enough to prevent current leakage, David said. A material's "k" value refers to its ability to compress electrical fields.
The company is not releasing the properties or identity of the new material, he said. It allows about 100 times less current to leak from the transistor and improves the capacitance of the transistor by up to 60 percent, as compared to silicon dioxide, David said. Improved capacitance results in faster transistors, he said.
But this new high-k material does not work very well with the polysilicon gate electrodes currently used in Intel's transistors, David said. Due to incompatibilities between the high-k material and the polysilicon, the transistor requires more voltage in order to function, and the electrons flowing through the transistor move at a slower rate, he said.
To solve those problems, Intel will use a metal gate electrode when it rolls out the high-k material, David said. The company will use one kind of metal for positive transistors, and another for negative transistors, and tweak its process technology to allow both metals to interact, he said. Intel is also not disclosing the particular metals it selected.
AMD announced earlier this year that it would use nickel silicide gates in its transistors built on future process technologies.
Intel is currently in the process of rolling out its 90-nanometer process technology, with the first chips built on the process expected later this year and higher production levels expected by next year.