US Patent 10141431 Epitaxy source/drain regions of FinFETs and method forming same

A method includes forming isolation regions extending into a semiconductor substrate, and recessing the isolation regions, so that portions of semiconductor strips between the isolation regions protrude higher than the isolation regions to form semiconductor fins. The method further includes recessing the semiconductor fins to form recesses, epitaxially growing a first semiconductor material from the recesses, etching the first semiconductor material, and epitaxially growing a second semiconductor material from the first semiconductor material that has been etched back.