Transistors, semiconductor memory cells having a transistor and methods of forming the same are provided, the transistors may include a semiconductor substrate having a first semiconductor region. A gate pattern may be disposed on the first semiconductor region. Spacer patterns may each be disposed on a sidewall of the gate pattern. Second semiconductor regions and a third semiconductor regions may be disposed in the semiconductor substrate. The second semiconductor regions may be disposed under the spacer patterns. The third semiconductor regions may be disposed adjacent to the second semiconductor regions. The first semiconductor region may have a higher impurity ion concentration than the second semiconductor regions.