A non-volatile semiconductor memory includes a substrate having a substrate region, at least one word line, a plurality of non-volatile memory cells arranged in a plurality of sectors and further comprising first wells of a first doping type, electrically insulating elements and switching elements. Each sector includes a plurality of non-volatile memory cells commonly arranged in a respective first well. The at least one word line electrically connecting memory cells of a group of sectors among the plurality of sectors. The first wells are separated from the substrate region and from each other by means of the electrically insulating elements. Each first well is connected to a respective switching element and the semiconductor memory is constructed such that each first well is biasable to a predetermined potential by means of the respective switching element. Further, a method is provided for operating the above non-volatile semiconductor memory.