IBM's Strained Silicon Breakthrough Image Page

On June 8, 2001, IBM announced it has pioneered a new form of silicon -- called strained silicon -- to boost chip speeds up to 35 percent.

Scientists at IBM have discovered a breakthrough method to stretchsilicon, the fundamental material at the heart of microchips, that canspeed the flow of electrons through transistors, increasingsemiconductor performance and decreasing power consumption insemiconductors.

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Animation of Strained Silicon
The new technology takes advantage of the natural tendency for atomsinside compounds to align with one another. When silicon is deposited ontop of a substrate with atoms spaced farther apart, the atoms insilicon stretch to line up with the atoms beneath, stretching -- or"straining" -- the silicon. In the strained silicon, electronsexperience less resistance and flow up to 70 percent faster, which canlead to chips that are up to 35 percent faster -- without having toshrink the size of transistors.


strain_silicon_web.mov.qt - Quicktime movie

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A transistor built with strained silicon.
    
Click to view high-resolution version     
Click to view media print quality TEM color enhanced image A transistor built with strained silicon. The silicon is "stretchedout" because of the natural tendency for atoms inside compounds toalign with one another. When silicon is deposited on top of a substratewith atoms spaced farther apart, the atoms in silicon stretch to line upwith the atoms beneath, stretching -- or "straining" -- the silicon.In the strained silicon, electrons experience less resistance and flowup to 70 percent faster, which can lead to chips that are up to 35percent faster -- without having to shrink the size of transistors.

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The image on the left shows electrons flowing through a current silicon chip.

On the right is an imageof electrons flowing through "strained silicon". The electrons flow upto 70 percent faster through strained silicon because there is lessresistance, resulting in chip speed increases of up to 35 percent. IBMscientists are able to strain, or stretch the silicon by takingadvantage of the natural tendency of atoms inside of different crystalsto align with one another. When silicon is deposited on top of anothermaterial which has atoms spaced farther apart -- in this case, silicongermanium -- the atoms in silicon stretch to line up with the atomsbeneath.

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The image on the left shows an array of atoms in a silicon lattice(top) and a silicon germanium lattice (bottom). Note the distance inthe silicon germanium lattice is spread farther apart than in thesilicon.

The image on the right shows when we put silicon on top of silicongermanium, the atoms in the silicon stretch, or "strain" to align withthe atoms in the silicon germanium. In the strained silicon, electronsexperience less resistance and flow up to 70 percent faster, which canlead to chips that are up to 35 percent faster -- without having toshrink the size of transistors.