Electrically erasable, directly overwritable, multibit single cell memory elements and arrays fabricated therefrom
Electrically erasable memory elements having improved set resistance stability Patent #: 5414271
ApplicationNo. 517313 filed on 08/21/1995
US Classes:257/3, With means to localize region of conduction (e.g., "pore" structure)257/2, Bulk effect switching in amorphous material257/5, In array257/E27.004, Including solid state component for rectifying, amplifying, or switching without a potential barrier or surface barrier (EPO)257/E45.002Bistable switching devices, e.g., Ovshinsky-effect devices (EPO)
ExaminersPrimary: Larkins, William D.
Attorney, Agent or Firm
International ClassH01L 045/00
AbstractDisclosed herein is a solid state, directly overwritable, non-volatile, high density, low cost, low energy, high speed, readily manufacturable, single cell memory element having reduced switching current requirements and an increased thermal stability of data retention. The memory element includes a volume of memory material which is a transition metal modified chalcogen. The transition metal may be selected from the group consisting of Nb, Pd, Pt and mixtures or alloys thereof. The memory material may further include at least one transition metal selected from the group consisting of Fe, Cr, Ni and mixtures or alloys thereof. The memory element exhibits orders of magnitude higher switching speeds at remarkably reduced switching energy levels. The novel memory element of the instant invention is in turn characterized, inter alia, by at least two stable and non-volatile detectable configurations of local atomic and/or electronic order, which configurations can be selectively and repeatably accessed by electrical input signals of designated energy levels. The memory elements are further characterized by enhanced thermal stability of data retention, which stability is achieved by elementally modifying Te--Ge--Sb semiconductor material from which previous memory elements were fabricated.