Posts Tagged ‘atom’

The ideal crystalline structure of graphene is...

The ideal crystalline structure of graphene is a hexagonal grid. (Photo credit: Wikipedia)

Imagine a material that is just one atom thick, 300 times stronger than steel, harder than diamond, a fantastic conductor of heat and electricity and super-flexible to boot.This might sound like the stuff of science fiction, but believe it or not, such a material already exists.The name of this supermaterial is graphene and it’s one of the most exciting prospects in science today.In the latest graphene-related research – released last week – researchers from Vanderbilt University found a way to overcome one of graphene’s most problematic flaws – a high sensitivity to external influences which causes graphene-based devices to operate more slowly than they should.The researchers found a way to dampen external influences on the graphene, and could then observe electrons moving through their graphene three times faster than was previously possible.This development could pave the way for a new generation of graphene-based devices including touch screens and solar panels.More on the uses of graphene in a moment, but first: what is graphene?Quite simply, graphene is a new structural form or ‘allotrope’ of carbon – one of the most versatile elements in the universe. It was discovered in 2004 by Russian-born physicists Andre Geim and Konstantin Novoselov, who jointly received the 2010 Nobel Prize in Physics for their troubles.Graphene is a single, flat layer of carbon atoms packed tightly into a two-dimensional honeycomb arrangement. The in-plane two-dimensional carbon-carbon bonds in graphene are the strongest bonds known to science. It is these bonds that give graphene its unbelievable mechanical strength and flexibility.Graphene is essentially a single layer of graphite, the material found in pencil ‘lead’. When you draw on paper with a pencil, weakly bound graphene sheets in the graphite spread over your paper like a pack of cards.But because graphene is so thin – the thickness of a single carbon atom – it is extremely difficult to see. This is one of the reasons it took researchers so long to find graphene sheets among thicker stacks of graphite.Despite being so thin, graphene is an excellent conductor of electricity. Electrons flow through graphene with almost zero electrical resistance. This unusual property, and the fact graphene is nearly invisible, makes it an ideal material for the transparent electrodes used in computer displays and solar cells.While scientists have known about graphene since 2004, it was in 2010 that researchers from Samsung and Sungkyunkwan University took a critical step in developing the commercial applications of this material.

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via Harder than diamond, stronger than steel Science Alert.

Tomorrow’s Transistor, Built Atom by Atom

Applied Materials announces the details of a machine for making the next generation of transistors.

Thursday, July 14, 2011

By Katherine Bourzac

  • Chip stack: This illustration shows the layers that make up a gate in a 22-nanometer transistor. The white balls on the bottom are silicon. The light blue balls in the middle are silicon dioxide molecules; the larger turquoise balls higher up are hafnium oxide; and the yellow balls are nitrogen atoms.
    Credit: Applied Materials

Applied Materials, the world’s leading supplier of manufacturing equipment to chipmakers, has announced a new system for making one of the most critical layers of the transistors found in logic circuits.

Applied Materials’ new tool, called Centura, announced at the Semicon West conference in San Francisco on Tuesday, deposits a critical layer in transistors one atom at a time, providing unprecedented precision.

As chipmakers scale transistors down to ever-smaller sizes, enabling speedier and more power-efficient electronics, atomic-scale manufacturing precision is a growing concern. The first chips with transistors just 22 nanometers in size are going into production this year, and at that size, even the tiniest inconsistencies can mean that a chip intended to sell at a premium must instead be used for low-end gadgetry.

Transistors are made up of multiple layers: an active silicon material topped with an interfacing layer and then a layer of a material called a dielectric, which makes up the “gate” that switches the transistor on and off.

Applied Materials sells equipment for depositing these layers, called the gate stack, on top of silicon wafers. In the switch from today’s 32-nanometer to the next generation of 22-nanometer transistors, it’s become trickier to make the gate. The interface and dielectric layers both have to get thinner, and the behavior of the layers can be affected by tiny flaws where the materials touch. And as the layers get thinner, tiny flaws can be magnified even more than in larger transistors made from thicker layers.

Manufacturing accuracy will be even more important in the next-generation three-dimensional transistors that chipmaker Intel will begin producing later this year. In these devices, the active area is a raised strip that the interface and gate layers contact on three sides. This increased area of contact helps these devices perform better, but it also means an increased vulnerability to flaws.

Centura uses atomic-layer deposition, or ALD, which lays down a single atomic layer of the dielectric at a time. This method is more expensive, but it’s become necessary, says Atif Noori, global product manager of Applied Materials’ ALD division. For the heart of the transistor—the gate—to work, “you have to make sure you’re putting all the atoms right where you want them.”

One source of inconsistencies in microchips is exposure to air. In Applied Materials’ new tool, the entire process of depositing the gate stack is done in a vacuum, one wafer at a time. Making the gate stack entirely under a vacuum also leads to a 5 to 10 percent increase in the speed at which electrons travel through the transistor; this can translate into power savings or faster processing. Ordinarily, there’s significant variation in the amount of power it takes to turn on a given transistor on a chip; manufacturing under a vacuum tightens that distribution by 20 to 40 percent.

via Tomorrow’s Transistor, Built Atom by Atom – Technology Review.