A programmable
semiconductor device has a switch element in an
interconnection layer, wherein in at least one of the inside of a via, interconnecting a wire of a first
interconnection layer and a wire of a second
interconnection layer, a contact part of the via with the wire of the first interconnection layer and a contact part of the via with the wire of the second interconnection layer, there is provided a variable electrical
conductivity member, such as a member of an
electrolyte material. The via is used as a variable electrical
conductivity type switch element or as a
variable resistance device having a contact part with the wire of the first interconnection layer as a first terminal and having a contact part with the wire of the second interconnection layer as a second terminal. By varying the electrical
conductivity of the switch element, the state of connection of the via with the wire of the first interconnection layer and the state of connection of the via with the wire of the second interconnection layer may be variably set to a shorted state, an open-circuited state or to an
intermediate state A two-state switch element includes an
ion conductor for conducting
metal ions interposed between the first and second electrodes. The second
electrode is formed of a material lower in reactivity than the first
electrode. The electrical conductivity across the first and second electrodes is changed by the oxidation-reduction reaction of the
metal ions. There are provided first and second transistors of opposite polarities, connected to the first
electrode, and third and fourth transistors of opposite polarities, connected to the second electrode.