A semiconductor device includes a base isolation layer, a first transistor with a first source electrode at a first side of the base isolation layer. A bridge pillar extends through the base isolation layer, and a metal electrode electrically connects the bridge pillar to the first source electrode. The metal electrode and the first source electrode are at the same side of the base isolation layer. A second metal electrode at an opposite side of the base isolation layer electrically connects to the bridge pillar and to a conductive line at the second side of the base isolation layer.