How Intel shrank processors to 45nm without taking a leak

Pictured left is a die shot of one of Intel's new 45nm Penryn processors, which the company claims represent the biggest breakthough since the sixties. Its development forced Intel to address one of the biggest problems of miniaturisation: leakage current.

A standard transistor of the type used in processors consists of source and drain electrodes sitting in a silicon substrate with a tiny gap between them. Above this gap is a thin layer of insulator, or dielectric; and sitting on that is the gate electrode (click image at right for pop-up diagram). Toggling the voltage at the gate toggles the charge distribution across the gap, and thus its ability to pass current.

This solid-state switch is never quite perfect because there are tiny current flows even in the off state. Most important is the "leakage" across the insulating layer under the gate. This layer is made of silicon dioxide (SiO2) in current designs and when it becomes only a few atoms thick, as it does as processor transistors get smaller, leakage becomes prohibitively high.

So why not have thicker insulation? The problem is that the thinner the layer, the higher is the capacitance of the structure - the amount of charge it can hold. The higher the capacitance, the better the current flow in the on state, and the faster the switching. In other words if you thicken the insulation to reduce leakage, you slow the transistor down.

What Intel has done is to replace the SiO2 with a 'high K dielectric', based on the element Hafnium, which allows a thicker (and thus less leaky) layer of insulation without reducing the capacitance.

Intel has also replaced the usual silicon gate with what it vaguely refers to as a mix of metals. Kaizad Mistry, product manager for Intel's 45nm logic technology development, said Intel was keeping this secret as the precise proportions of these and hafnium are critical.

The overall effect is to boost current flow in the on state, providing fast switching, and cutting leakage in the off state.

Intel claims that relative to 65nm technology the Penryn chips will pack twice as many transistors in a given area, with a 30 percent reduction in switching power, 20 percent faster switching, and a tenfold reduction in leakage across the gate dielectric. It also claims a fivefold reduction in current leaking between the source and drain.

reposted from: http://labs.pcw.co.uk/2007/01/how_intel_shran.html

my highlights / edits

Intel shows off next generation transistors

Computers the world over are about to get a makeover. Intel, the world's largest computer chip maker, announced on Saturday that its next generation transistors will have metal - not silicon - gate electrodes. They will also have insulating walls made of a "high-K" hafnium (wikipedia) compound, which is transparent to electric fields, instead of silicon dioxide.

reposted from: NewScientist.com news service
my highlights / edits

The changes mean that the 45-nanometre transistors on Intel's next suite of computer processors will not only be faster and smaller than today's 65-nanometre ones, they will also be more power efficient. That combination has been difficult to achieve in the past.

"The implementation of high-k and metal materials marks the biggest change in transistor technology since the introduction of polysilicon gate transistors in the late 1960s," says Intel co-founder Gordon Moore.

The new transistors will make their way into Intel's next generation products, currently codenamed "Penryn", which include the Core 2 Duo, Core 2 Quad and Xeon processors. These will run Windows Vista, Mac OS X, Windows XP and Linux.

Leaky materials

Intel first announced that it would start using the new materials at the end of 2003 (see Intel claims plug for leaky chips). But on Saturday it announced that manufacturing will begin later in 2007, with the first products available in 2008.

"It's no longer a research project, it's real," says Dan Hutcheson, an analyst with VLSI Research in California, US. "This is a really big breakthrough."

A transistor consists of an electrode that switches the current on and off within a "channel" using an electric field. In the past, to make the transistor switch faster, and thereby up its performance, chip makers shortened the electrode and thinned the insulating wall that separates it from the channel.

This is far from ideal, as thinning the wall causes current to leak from the channel into the electrode, wasting heat and electricity. Furthermore, it means more current leakage than the transistor could handle.

Switching speed

Now, in an effort to continue shrinking and speeding up its transistors, Intel has come up with an insulator that transmits a fast-switching electric field even at a relatively large size. The exact composition of this "high-k" material is a secret, but Intel says that it contains hafnium. It is claimed to increase transistor switching speed by 20% and leak five times less current.

In 2003, Intel also had to tweak its process to start making 90 nanometre transistors. Its secret then was to use "strained silicon" in its transistors (see Secret of strained silicon chips revealed). This increased the speed at which current flowed, although Hutcheson says that advance was "a walk in the park" compared with achieving today's leap to high-k insulators.

The change in insulator has also led to a change in the gate electrode material. When high-k materials are deposited next to an electrode made of polysilicon, defects normally arise at the boundary. But this effect disappears when a metal gate is used instead.

Using the new 45 nanometre transistors, dual-core processors will contain 400 million transistors, while quad-core will contain 800 million.

Intel chips push through nano-barrier

New materials have had to be developed to shrink the transistors. TINY TRANSISTORS on this Intel silicon wafer contain the element hafnium, which will necessitate new manufacturing tricks.

The next milestone in the relentless pursuit of smaller, higher performance microchips has been unveiled.

Chip-maker Intel has announced that it will start manufacturing processors using transistors just 45 nanometres (billionths of a metre) wide (wikipedia).

Shrinking the basic building blocks of microchips will make them faster and more efficient.

reposted from: http://news.bbc.co.uk/1/hi/technology/6299147.stm
my highlights / edits

Computer giant IBM has also signalled its intention to start production of chips using the tiny components.

"Big Blue", which developed the transistor technology with partners Toshiba, Sony and AMD, intends to incorporate them into its chips in 2008.

Intel said it would start commercial fabrication of processors at three factories later this year.

Critical leaks

The development means the fundamental "law" that underpins the development of all microchips, known as Moore's Law, remains intact.

The proposition, articulated by Intel co-founder Gordon Moore in 1965, states that the number of transistors on a chip could double every 24 months.

After more than 10 years of effort, we now have a way forward Tze-chiang Chen, IBM

The new Intel processors, codenamed Penryn, will pack more than four hundred million transistors into a chip half the size of a postage stamp.

Like current processors, they will come in dual-core and quad-core versions, meaning they will have two or four separate processors on each chip. The company has not said how fast the new devices will run.

The production of 45nm technology has been the goal of chip manufacturers ever since they conquered 65nm transistors.

A transistor is a basic electronic switch. Every chip needs a certain number of them, and the more there are and the faster they can switch, the more calculations chips can do.

For more than 45 years, chip manufacturers have managed to keep up with Moore's Law, shrinking transistor size and packing more and more of them on to chips.

However, past the 65nm barrier the silicon used to manufacture critical elements of the switches known as gate dielectrics no longer performs as it does at larger scales.

As a result, currents passing through the transistors leak and reduce the effectiveness of the chip.

To prevent this, researchers have had to develop new materials to contain the current at such small scales. The class of silicon substitutes are known as high-k metals.

Same 'tools'

Their development and integration into working components was described by Gordon Moore as "the biggest change in transistor technology" since the late 1960s.

The first working chips to incorporate 45nm devices were demonstrated last year by Intel, but they have never been incorporated into commercial products.

Dr Tze-chiang Chen, vice president of science and technology at IBM Research, said: "Until now, the chip industry was facing a major roadblock in terms of how far we could push current technology.

"After more than 10 years of effort, we now have a way forward."

The exact recipes for the different high-k metals used by Intel and IBM have not been disclosed, but importantly both firms have said that they could be incorporated into current production technology with minimal effort.