Intel Announces Breakthrough In Chip Transistor Design

SANTA CLARA, Calif., Nov. 26, 2001 -- Intel Corporation todayannounced that its researchers have developed an innovative transistorstructure and new materials that represent a dramatic improvement intransistor speed, power efficiency and heat reduction. The technologydevelopment is an important milestone in the effort to maintain thepace of Moore's Law and remove the technical barriers that Intel andthe semiconductor industry have only recently begun to identify.

The technology breakthrough, coupled with recent announcements fromIntel on faster and smaller transistors, will enable powerful newapplications such as real-time voice and face recognition, computingwithout keyboards, and smaller computing devices with higherperformance and improved battery life.

"Our research has shown that we can continue to make smaller andfaster transistors, but there are fundamental problems we need toaddress around power consumption, heat generation, and currentleakage," said Gerald Marcyk, director of components research, IntelLabs. "Our goal is to overcome these barriers and produce chips thathave 25 times the number of transistors of today's microprocessors atten times the speed with no increase in power consumption."

Intel researchers will discuss two major elements of the newtransistor structure at the International Electron Device Meeting(IEDM) in Washington D.C. on Dec. 3. Intel's technical papers willaddress power consumption, current leakage, and heat issues with twosignificant improvements to existing transistor design: a new type oftransistor called a "depleted substrate transistor" and a new materialcalled a "high k gate dielectric." Together, these advancementsdramatically reduce current leakage and power consumption.

Power consumption as a limiting factor

As semiconductors become more complex and new milestones intransistor size and performance are achieved, power consumption andheat have recently emerged as limiting factors to the continued pace ofchip design and manufacturing. Applying existing designs to futureprocessors becomes unworkable because of current leakage in thetransistor structure, which in turn requires more power and generatesmore heat. Transistors are the microscopic, silicon-based switches thatprocess the ones and zeros of the digital world.

Intel has already developed the world's smallest and fastest CMOStransistors, including a 15 nanometer transistor, which will enablechips with up to one billion transistors by the second half of thisdecade. However, as hundreds of millions, and even billions of smallerand faster transistors get packed on to a single piece of silicon thesize of a thumbnail, power consumption and the amount of heat generatedin the processor core becomes a significant technical challenge. Usingexisting methods of semiconductor design would eventually lead to chipsthat are simply too hot for desktop computers and servers. Theselimitations could even prevent new chip designs from being implementedin smaller computers like mobile PC's and handheld devices.

"Smaller and faster just isn't good enough anymore," Marcyk said."Power and heat are the biggest issues for this decade. What we aredoing with our new transistor structure is helping make devices thatare extremely power efficient, concentrating electrical current whereit's needed."

The new structure is being called the Intel TeraHertz transistorbecause the transistors will be able to switch on and off more than onetrillion times per second. In comparison, it would take a person morethan 15,000 years to turn a light switch on and off a trilliontimes.

Depleted substrate transistor

One element of the new structure is a "depleted substratetransistor," which is a new type of CMOS device where the transistor isbuilt in an ultra-thin layer of silicon on top of an embedded layer ofinsulation. This ultra-thin silicon layer, which is different thanconventional silicon-on-insulator devices, is fully depleted to createmaximum drive current when the transistor is turned on, enabling thetransistor to switch on and off faster.

In contrast, when the transistor is turned off, unwanted currentleakage is reduced to a minimum level by the thin insulating layer.This allows the depleted substrate transistor to have 100 times lessleakage than traditional silicon-on-insulator schemes. Anotherinnovation of Intel's depleted substrate transistor is theincorporation of low resistance contacts on top of the silicon layer.The transistor can therefore be very small, very fast and consume lesspower.

New material replaces silicon dioxide

Another key element is the development of a new material thatreplaces silicon dioxide on the wafer. All transistors have a"gate-dielectric," a material that separates a transistor's "gate" fromits active region (the gate controls the on-off state of thetransistor). The record-setting transistors introduced in the past yearhad gate dielectrics made of silicon dioxide that are only 0.8nanometers, or approximately three atomic layers thick. However, theleakage through this atomically thin insulator layer is becoming one ofthe largest sources of power consumption of chips.

At the IEDM conference, Intel researchers will demonstrate recordspeed for transistors made with a new type of material called a "high kgate dielectric." This new material reduces gate leakage by more than10,000 times compared to silicon dioxide. The high k gate material isgrown by a revolutionary technology called "atomic layer deposition" inwhich the new material can be grown in layers only one molecule thickat a time. The result is higher performance, reduction of heat, andsignificantly longer battery life for mobile applications.

The Intel TeraHertz transistor solves a key barrier to bringingfuture chips into volume production that enable a whole new range ofapplications. Intel is expected to begin incorporating elements of thisnew structure into its product line as early as 2005.

For more information on the TeraHertz transistor and other siliconresearch at Intel, visit Intel's Silicon Showcase atwww.intel.com/research/silicon.