The effect of the gate material on soft breakdown is studied by using Hg instead of poly-Si as gate material. It is demonstrated that soft breakdown occurs also in Hg-gate capacitors with a probability that exhibits the same dependence on the oxide thickness and the stress voltage as observed in poly-Si gate capacitors. These results indicate that soft breakdown is a phenomenon independent of the gate material, i.e., influenced more by the details of the energy discharge in the conduction spot at the moment of breakdown than by the details of charge injection and defect accumulation in the oxide.