Patent ID: 9735155
Date: 2017-08-15
CPC Classifications: H01L

Claim:
1. A bulk SiGe FinFET comprising: a plurality of SiGe fins and a bulk semiconductor substrate, the SiGe fins extending from the bulk semiconductor substrate; the SiGe fins having a top SiGe portion and a bottom SiGe portion, a part of the bottom SiGe portion being doped to form a punchthrough stop; the bulk semiconductor substrate having a top portion in contact with the bottom SiGe portions of the SiGe fins and comprising a gradient of germanium and silicon, and a bottom portion of silicon in contact with the top portion such that the gradient has a composition of SiGe at the top portion in contact at an interface with the SiGe fins that is the same composition of SiGe as in the SiGe fins, the proportion of germanium atoms in the gradient gradually decreasing from the interface and the proportion of silicon atoms in the gradient gradually increasing in the gradient from the interface until the bulk semiconductor substrate top portion contacts at a second interface the bulk semiconductor substrate bottom portion.