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 stretch silicon, the fundamental material at the heart of microchips, that can speed the flow of electrons through transistors, increasing semiconductor performance and decreasing power consumption in semiconductors.
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Animation of Strained Silicon
The new technology takes advantage of the natural tendency for atoms inside compounds to align with one another. When silicon is deposited on top of a substrate with atoms spaced farther apart, the atoms in silicon stretch to line up with the atoms beneath, stretching -- or "straining" -- the silicon. In the strained silicon, electrons experience less resistance and flow up to 70 percent faster, which can lead to chips that are up to 35 percent faster -- without having to shrink the size of transistors.
A transistor built with strained silicon. The silicon is "stretched out" because of the natural tendency for atoms inside compounds to align with one another. When silicon is deposited on top of a substrate with atoms spaced farther apart, the atoms in silicon stretch to line up with the atoms beneath, stretching -- or "straining" -- the silicon. In the strained silicon, electrons experience less resistance and flow up to 70 percent faster, which can lead to chips that are up to 35 percent faster -- without having to shrink the size of transistors.
On the right is an image of electrons flowing through "strained silicon". The electrons flow up to 70 percent faster through strained silicon because there is less resistance, resulting in chip speed increases of up to 35 percent. IBM scientists are able to strain, or stretch the silicon by taking advantage of the natural tendency of atoms inside of different crystals to align with one another. When silicon is deposited on top of another material which has atoms spaced farther apart -- in this case, silicon germanium -- the atoms in silicon stretch to line up with the atoms beneath.
The image on the left shows an array of atoms in a silicon lattice (top) and a silicon germanium lattice (bottom). Note the distance in the silicon germanium lattice is spread farther apart than in the silicon.
The image on the right shows when we put silicon on top of silicon germanium, the atoms in the silicon stretch, or "strain" to align with the atoms in the silicon germanium. In the strained silicon, electrons experience less resistance and flow up to 70 percent faster, which can lead to chips that are up to 35 percent faster -- without having to shrink the size of transistors.
