Intel Corp. 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, the company announced today.
When Intel rolls out its 45-nanometer 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 for media and analysts. Intel fellow Robert Chau will provide additional details about the new technologies in a paper to be presented to attendees at the International Workshop on Gate Insulator in Tokyo tomorrow.
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 at Mercury Research Inc. in Cave Creek, Ariz.
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 isn't 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%, compared with silicon dioxide, David said. Improved capacitance results in faster transistors.
The new high-k material doesn't work very well with the polysilicon gate electrodes currently used in Intel's transistors, however, David said. Due to incompatibilities between the high-k material and the polysilicon, the transistor requires more voltage to function, and the electrons flowing through it 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.
Advanced Micro Devices Inc. announced earlier this year that it would use nickel silicide gates in its transistors built on future process technologies.
Intel is in the process of rolling out its 90-nm process technology, with the first chips built on the process expected later this year and higher production levels expected by next year.
Before switching to the high-k gate dielectrics and metal gate electrodes, Intel will make the transition to a 65-nm process technology. Although Intel has made no formal announcements about its 65-nm process, it is expected to use similar techniques used in the 90-nm technology, according to a road map shown during David's presentation.