An embodiment semiconductor device includes a nanowire extending upwards from a semiconductor substrate, a source/drain region in the nanowire, and a channel region in the nanowire over the source/drain region. The source/drain region further extends into the semiconductor substrate past edges of the nanowire. The semiconductor device further includes a gate structure encircling the channel region and a silicide in an upper portion of the source/drain region. A sidewall of the silicide is aligned with a sidewall of the gate structure.