In a method of forming a wire structure, first active regions and second active regions are formed on a substrate. Each of the first active regions has a first sidewall of a positive slope and a second sidewall opposed to the first sidewall. The second active regions are arranged along a first direction. An isolation layer is between the first active regions and the second active regions. A first mask is formed on the first active regions, the second active regions and the isolation layer. The first mask has an opening exposing the first sidewall and extending along the first direction. The first active regions, the second active regions and the isolation layer are etched using the first mask to form a groove extending along the first direction and to form a fence having a height substantially higher than a bottom face of the groove. A wire is formed to fill the groove. A contact is formed on the wire. The contact is disposed toward the second active regions from the fence.