US Patent 7459717 Phase change memory cell and manufacturing method

A phase change memory cell includes first and second electrodes having generally coplanar surfaces spaced apart by a gap and a phase change bridge electrically coupling the first and second electrodes. The phase change bridge may extend over the generally coplanar surfaces and across the gap. The phase change bridge has a higher transition temperature bridge portion and a lower transition temperature portion. The lower transition temperature portion comprises a phase change region which can be transitioned from generally crystalline to generally amorphous states at a lower temperature than the higher transition temperature portion. A method for making a phase change memory cell is also disclosed.