P-channel MOSFET devices are used as reprogrammable fuse or antifuse
elements in a memory decode circuit by utilizing anomalous hole
generation. An applied negative gate bias voltage is sufficiently large
to cause tunnel electrons to gain enough energy to exceed the band gap
energy of the oxide. This causes energetic hole-electron pairs to be
generated in the silicon substrate. The holes are then injected from the
substrate into the oxide, where they remain trapped. A large shift in the
threshold voltage of the p-channel MOSFET results. The device can
subsequently be reset by applying a positive gate bias voltage. Various
circuits incorporating such fuse or antifuse elements are also disclosed.