Abstract:
A phase change memory formed by a plurality of phase change memory devices having a chalcogenide memory region (28) extending over an own heater (26). The heaters (26) have all a relatively uniform height. The height uniformity is achieved by forming the heaters within pores in an insulator that includes an etch stop layer (18) and a sacrificial layer (24). The sacrificial layer is removed through an etching process such as chemical mechanical planarization. Since the etch stop layer may be formed in a repeatable way and is common across all the devices on a wafer, considerable uniformity is achieved in heater height. Heater height uniformity results in more uniformity in programmed memory characteristics.
Abstract:
A ring shaped heater (26) surrounds a chalcogenide region (36) along the length of a cylindrical solid phase portion (35) thereof defining a change phase memory element. The chalcogenide region (36) is formed in a sub-lithographic pore (34), so that a relatively compact structure is achieved. Furthermore, the ring contact between the heater and the cylindrical solid phase portion (35) results in a more gradual transition of resistance versus programming current, enabling multilevel memories to be formed.