A p-channel non-volatile memory (NVM) transistor is programmed by shifting
the threshold voltage of the transistor. The threshold voltage is shifted
by introducing a programming current to the gate electrode of the
transistor, and simultaneously introducing a negative bias to the
transistor. The threshold voltage of the p-channel NVM transistor is
shifted in response to the negative bias condition and the heat generated
by the programming current. The high temperature accelerates the
threshold voltage shift. The threshold voltage shift is accompanied by an
agglomeration of material in the gate electrode. The agglomeration of
material in the gate electrode is an indication of the high temperature
reached during programming. The threshold voltage shift of the p-channel
NVM transistor is permanent.