Germanium-rich metal contact layers for pmos source and drain contacts

An apparatus, comprising:

• a substrate comprising silicon;
• a first layer located on the substrate, the first layer comprising silicon and germanium;
• and
• a second layer comprising a metal and germanium located on the first layer, a portion of the second layer located on the first layer, wherein a minimum atomic percentage of germanium in the first layer and the second layer taken along a line from a point about three nanometers into the first layer from an interface between the first layer and the second layer to a point about three nanometers into the second layer from the interface is within an order of magnitude of a maximum atomic percentage of germanium taken along the line.

A system comprising:

• an integrated circuit component comprising:
• a substrate comprising silicon;
• a first layer located on the substrate, the first layer comprising silicon and germanium, the first layer a source or drain region of a p-channel metal-oxide-semiconductor (PMOS) field effect transistor;
• and
• a second layer comprising a metal and germanium located on the first layer, a portion of the second layer located on the first layer, wherein a minimum atomic percentage of germanium in the first layer and the second layer taken along a line from a point about five nanometers into the first layer from an interface between the first layer and the second layer to a point about five nanometers into the second layer from the interface is within an 50% of a maximum atomic percentage of germanium taken along the line;
• and
• a printed circuit board, the integrated circuit component attached to the printed circuit board.