A semiconductor device having a dual trench and methods of fabricating the same, a semiconductor module, an electronic circuit board, and an electronic system are provided. The semiconductor device includes a semiconductor substrate having a cell region including a cell trench and a peripheral region including a peripheral trench. The cell trench is filled with a core insulating material layer, and the peripheral trench is filled with a padding insulating material layer conformably formed on an inner surface thereof and a core insulating material layer formed on an inner surface of the padding insulating material layer. The core insulating material layer has a greater fluidity than the padding insulating material layer.