Patent ID: 7166875

Claim:
A diode on a silicon substrate, comprising: an active region in the silicon substrate, the active region being heavily doped with a first type dopant; a first refractory metal silicide layer contacting and covering at least a portion of the active region; an insulation layer contacting and covering at least a portion of the first refractory metal silicide layer, the insulation layer having a diode opening extending therethrough and communicating with the first refractory metal silicide layer; a polysilicon plug disposed within the diode opening and contacting the first refractory metal silicide layer, the polysilicon plug comprising: a bottom portion in contact with the first refractory metal silicide layer and being lightly doped with the first type dopant, and a top portion in contact with the bottom portion; and a material that is capable of changing states and resistivities vertically over and in communication with the polysilicon plug.