Semiconductor device and operation method thereof

A method comprising:

• providing one or more memory elements each including (1) a first semiconductor layer of a first conductivity type, (2) second and third semiconductor layers of a second conductivity type, which are disposed separated from each other in the first semiconductor layer, (3) a dielectric film on a lower-layer side and a conductive film on an upper-layer side, which are provided in a region corresponding to a portion between the second and third semiconductor layers on the first semiconductor layer, (4) a first electrode electrically connected to the second semiconductor layer, (5) a second electrode electrically connected to the third semiconductor layer, (6) and a third electrode electrically connected to the conductive film;
• and
• performing a write operation on at least one of the memory elements by
• (a) applying to each memory element on which a write operation is performed a voltage equal to or higher than a predetermined threshold between the second and third electrodes, thereby causing an electric current to flow between the conductive film and the third semiconductor layer and causing a dielectric breakdown of a least a portion of the dielectric film;
• and
• (b) forming in each memory element on which a write operation is performed a filament in the portion between the second and third semiconductor layers, the filament being a conductive path between the second and third semiconductor layers.