Patent ID: 7642538

Claim:
A switching element comprising: a pair of input/output electrodes provided on a substrate separately from each other; a phase change film provided in contact with the electrodes, a resistance of the phase change film being varied in accordance with a history of heating, the phase change film being crystallized and provided with a low resistance when the phase change film is heated to a first temperature suitable for crystallization, and being made amorphous and provided with a high resistance when the phase change film is heated to a second temperature higher than the first temperature; an interlayer insulation film formed on the phase change film; and a heating mechanism which is formed on the interlayer insulation film and heats the phase change film, the heating mechanism including: (i) a pair of current supply electrodes arranged on the interlayer insulation film and being apart from each other; (ii) a resistance heating film formed on the interlayer insulation film, having one end connected to one of the current supply electrodes, and configured to heat the phase change film; and (iii) a nonlinear resistor element formed on the interlayer insulation film, connected between the other end of the resistance heating film and the other one of the current supply electrodes, and showing different resistance values depending upon directions in which a current is supplied, wherein the phase change film is heated to the first temperature by the resistance heating film when a predetermined voltage is applied between the current supply electrodes in one direction, and the phase change film is heated to the second temperature by the resistance heating film when the predetermined voltage is applied between the current supply electrodes in a direction opposite to said one direction.