Transistor Advancements Rekindle Rivalry

Two Silicon Valley chipmaking heavyweights Thursday went toe to toe over which company has the most advanced transistors.

At a technology conference in Kyoto, Japan this week, Intel and Advanced Micro Devices outlined their progress in building low-power, high-speed components for various types of computers. The debate only fuels the flames between two bitter rivals.

The key ingredient of all digital circuits, transistors amplifies a signal or opens or closes a circuit. The industry trend has been to cram as many as possible into processors and chip dies to help increase processor and memory speeds.

As part of its quest to outsmart Moore’s Law , Santa Clara, Calif.-based Intel said it’s 3-D tri-gate transistor is moving from research to the development phase and is expected to appear on the market in 2007 using 45-nm process technology.

The No. 1 chipmaker says as transistors shrink to less than 30 nanometers (nm), the increase in current leakage means that transistors require increasingly more power to function correctly, which generates massive amounts of heat. Intel’s answer is a transistor that looks a little like a top hat consisting of a raised plateau with vertical sides. The design allows electrical signals to be sent along the top of the transistor gate and along both vertical sidewalls tripling the space available for electrical signals to travel — something akin to turning a one-lane road into a three-lane highway, but without taking up more area. Intel says this gives its tri-gate transistor much higher performance than today’s planar (flat) transistors and makes it compatible with the future introduction of a high K gate dielectric for even lower leakage.

“The results place non-planar, 3-D transistor structures among the promising nanotechnology innovations that we will use to extend silicon scaling,” Intel senior vice president Sunlin Chou said in a statement.

Intel also said its researchers have developed a high-quality oscillator operating at 5GHz (the frequencies at which 802.11a operates) on the company’s CMOS process. This same 5GHz signal can also be used to generate signals for the 2.4GHz band (the frequency at which 802.11b and g operate). The oscillator is likened to a pacemaker for the radio and determines the frequency at which signals are transmitted and received.

In addition, Intel said it has produced a synthesizer running at 10GHz that lets radios switch between channels faster than before. The company said the technology, built using a 0.18-micron digital CMOS process, helps a radio locate and use the best spectrum in a given location. The goal is to ultimately increase bandwidth and extended coverage for wireless.

Not to be outdone, AMD detailed how it built its fully-depleted Silicon-on-Insulator (FDSOI) technology. As previously reported the SOI technology is expected to create an ultra-fast PMOS (P-channel metal-oxide semiconductor) transistor — 30 percent better than what is on the market now.

Rather than using Polysilicon, the gate material used in most transistors, AMD said it’s using a material called Nickel Silicide to make “metal gates” within the transistors.

“Nickel Silicide or other metal gate technologies could eventually lead to solving key challenges in the further shrinking of transistors beyond the 65nm production node,” AMD vice president of process technology development Craig Sander said in a statement. “Metal gate technologies provide a means to reduce the effective oxide thickness and alleviate the stringent requirements imposed on aggressive gate oxide scaling required for high performance transistors.”

Currently, SOI transistors are built on a thin top-layer of pure Silicon that sits atop another layer of insulating oxide. The insulating layer ensures that electrical current flows only through the thin top-layer of Silicon, and doesn’t leak down into the material that forms the bulk of the wafer.

AMD says the thinness of its silicon top-layer contributes to better transistor performance, in part because it minimizes undesirable electrical characteristics that could inhibit how well the transistor works.

The Sunnyvale, Calif.-based semiconductor maker also highlighted its Strained-Silicon and AMD metal gate technology. The company said its version pushes performance 25 percent higher than current NMOS (N-channel metal-oxide semiconductor) technology.

The company said its Strained-Silicon transistors offer increased performance potential due to the Silicon atoms being “strained” to enhance carrier mobility, which results in improved electrical current flow. Emerging research shows that SOI and Strained-Silicon can be integrated within the same fabrication process to achieve additive benefits.

While AMD designs its own transistors, it licenses its SOI technology from IBM .

IBM is also working on advanced transistors. Recently, its researchers made silicon channel devices and circuits on bonded silicon-on-insulator (SOI) wafers using halo implants and 248nm-wavelength lithography. With more aggressive halo, the IBM team claims it has produced the smallest working Metal Oxide Semiconductor Field Effect Transistor (MOSFET) reported to date, with 4nm silicon body and 6nm gate lengths.

The company is also working on a new silicon germanium (SiGe) transistor reach speeds of 350GHz

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