Non-volatile memory unit and its operation method and making process

A non-volatile memory unit device features that an actuating voltage applied to its grid is a negative one, so greatly improving its erasing effect. Three overlapped signals are provided for it, including two negative signals and one positive signal. For anothe implementation example, the memory unit is in a P trap inside N trap on P type substrate and two positive signals and two negative signals are used for erasing operation for higher erasing speed under a proper voltage, and lower requirement to voltage pump and driver circuit of chip.