A semiconductor device includes a fin-like structure extending along a first axis; a first source/drain feature disposed at a first end portion of the fin-like structure; and a constraint layer disposed at a first side of the first end portion of the fin-like structure, wherein the first source/drain feature comprises a first portion, disposed at the first side, the first portion comprising a shorter extended width along a second axis, and a second portion, disposed at a second side that is opposite to the first side, the second portion comprising a longer extended width along the second axis.