Provided are transistors, semiconductor integrated circuit interconnections and methods of forming the same. The transistors, semiconductor integrated circuit interconnections and methods of forming the same may improve electrical characteristics between gate electrodes or interconnection electrodes and simplify a semiconductor fabrication process related to gate electrodes or interconnection electrodes. A material layer having first and second regions may be prepared. A trench may be formed in a selected portion of the first region. Transistors or semiconductor integrated circuit interconnections may be in the first and second regions, respectively. One of the transistors or the semiconductor integrated circuit interconnections may be formed in the trench. The transistors or the semiconductor integrated circuit interconnections may be electrically insulated from each other.