Semiconductor structures employing strained material layers with defined impurity gradients and methods for fabricating same

A FET fabricated in a semiconductor substrate, the FET comprising a channel region including at least one strained channel layer, the at least one strained channel layer having a distal zone away from the substrate, wherein the substrate and the channel region are characterized at least in part by an impurity gradient having a value substantially equal to zero in the distal zone.

A method for fabricating a semiconductor structure in a substrate, the method comprising the steps of:

• disposing at least one strained layer on the substrate thereby defining an interface therebetween, the at least one strained layer having a distal zone away from the interface;
• and
• performing at least one subsequent processing step on the substrate after which an impurity gradient characterizing, at least in part, the substrate, the interface, and the at least one strained layer has a value substantially equal to zero in the distal zone.

A method for fabricating a FET in a semiconductor substrate, the FET comprising a channel region, the method comprising the steps of:

• disposing at least one strained channel layer in at least the channel region, the at least one strained channel layer having a distal zone away from the substrate;
• and
• performing at least one subsequent processing step on the substrate after which an impurity gradient characterizing, at least in part, the substrate and the at least one strained layer has a value substantially equal to zero in the distal zone.