A semiconductor device according to the present disclosure includes a channel member including a first connection portion, a second connection portion and a channel portion disposed between the first connection portion and the second connection portion, a first inner spacer feature disposed over and in contact with the first connection portion, a second inner spacer feature disposed under and in contact with the first connection portion, and a gate structure wrapping around the channel portion of the channel member. The channel member further includes a first ridge on a top surface of the channel member and disposed at an interface between the channel portion and the first connection portion. The first ridge partially extends between the first inner spacer feature and the gate structure.