Disclosed are a phase change memory cell and a method of forming the
memory cell. The memory cell comprises a main body of phase change
material connected directly to a bottom contact and via a narrow channel
of phase change material to a top contact. The channel is tapered from
the top contact towards the main body. A minimum width of the channel has
a less than minimum lithographic dimension and is narrower than a width
of the main body. Therefore, the channel provides a confined region for
the switching current path and restricts phase changing to within the
channel. In addition an embodiment of the memory cell isolates the main
body of phase change material by providing a space between the phase
change material and the cell walls. The space allows the phase change
material to expand and contract and also limits heat dissipation.