Patent attributes
A method includes providing a substrate, a semiconductor fin extending from the substrate, and a gate structure over the substrate and engaging the semiconductor fin; etching the semiconductor fin to form a source/drain trench; and epitaxially growing a source/drain feature in the source/drain trench, which includes epitaxially growing a first semiconductor layer having silicon germanium (SiGe); epitaxially growing a second semiconductor layer having SiGe above the first semiconductor layer; epitaxially growing a third semiconductor layer having SiGe over the second semiconductor layer; and epitaxially growing a fourth semiconductor layer having SiGe and disposed at a corner portion of the source/drain feature where the source/drain feature has a largest lateral dimension. Each of the first, second, third, and fourth semiconductor layers includes a p-type dopant, and the fourth semiconductor layer has a higher dopant concentration of the p-type dopant than each of the first, second, and third semiconductor layers.
