A carbon containing layer may be formed between a pair of chalcogenide
containing layers of a phase change memory. When the lower chalcogenide
layer allows current to pass, a filament may be formed therein. The
filament then localizes the electrical heating of the carbon containing
layer, converting a relatively localized region to a lower conductivity
region. This region then causes the localization of heating and current
flow through the upper phase change material layer. In some embodiments,
less phase change material may be required to change phase to form a
phase change memory, reducing the current requirements of the resulting
phase change memory.