Methods for forming a gate structure of a circuit structure are provide. The methods for forming the gate structure may include: forming a first gate pattern in a gate mask layer, the forming including a first etching of rounded corner portions of the first gate pattern; forming a second gate pattern in the gate mask layer, the second gate pattern at least partially overlapping the first gate pattern, the forming including a second etching of rounded corner portions of the second gate pattern; and, etching the gate mask layer using the first gate pattern and second gate pattern to form the gate structure.