A process is described for manufacturing an improved PMOS semiconductor transistor.
Recesses are etched into a layer of epitaxial silicon. Source and drain films are
deposited in the recesses. The source and drain films are made of an alloy of silicon
and germanium. The alloy is epitaxially deposited on the layer of silicon. The
alloy thus has a lattice having the same structure as the structure of the lattice
of the layer of silicon. However, due to the inclusion of the germanium, the lattice
of the alloy has a larger spacing than the spacing of the lattice of the layer
of silicon. The larger spacing creates a stress in a channel of the transistor
between the source and drain films. The stress increases IDSAT and IDLIN
of the transistor. An NMOS transistor can be manufactured in a similar manner
by including carbon instead of germanium, thereby creating a tensile stress.
