Strained silicon

Elongated silicon (English strained silicon ) is a process in the semiconductor art in which due to mechanical strain, the charge -carrier mobility of electrons and holes in the channel ( silicon ) of a metal-insulator- semiconductor field-effect transistor is influenced.

Design and operation

Elongated silicon comprises a silicon -germanium layer (SiGe), on which a thin silicon layer is applied. Due to the higher lattice constant of the SiGe layer with respect to silicon, i.e., greater spacing between the atoms, the crystal lattice of silicon is somewhat pulled apart at the point of contact of the SiGe and Si layers, so that the intervals between the Si atoms are larger.

The larger atomic distance reduces the interaction between the atoms, so that the charge carrier mobility and therefore the conductivity of the electrons is increased. This in turn leads to a up to 70% faster transit of the electrons through the silicon layer, and thus allows up to 35% higher switching speed of a transistor constructed therefrom. This in turn provides the ability to clock a processor thus constructed speed.

This is used, among other things, Intel and AMD / Globalfoundries in its current (2009) processors.