A method of forming dummy structures and an overlay mark protection zone over an active layer zone based on the shape of an overlay mark and the resulting device are provided. The DC motor has a rotating drive shaft, supported at its free end. The hybrid dcdc converter further comprises a selection network coupled to the first power source and the output of the low power converter and a main unregulated power converter coupled to the selection network. The voltage compensation circuit includes a voltage divider providing a divided voltage form a gate pulse signal, a comparing unit, a time counting unit and a processing unit. The time length for the first and second ISSG steps is determined based on a desired film thickness, a time length dependency of a film formed by the second ISSG process, and the oxidation rate of the first and second ISSG processes.