US 12,266,402 B2
Phase change memory device with improved retention characteristics and related method
Elisa Petroni, Sesto San Giovanni (IT); and Andrea Redaelli, Milan (IT)
Assigned to STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed by STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed on Nov. 23, 2022, as Appl. No. 17/993,118.
Claims priority of application No. 102021000030293 (IT), filed on Nov. 30, 2021.
Prior Publication US 2023/0170022 A1, Jun. 1, 2023
Int. Cl. G11C 13/00 (2006.01); H10N 70/00 (2023.01); H10N 70/20 (2023.01)
CPC G11C 13/0069 (2013.01) [H10N 70/231 (2023.02); H10N 70/8413 (2023.02); H10N 70/8828 (2023.02)] 19 Claims
OG exemplary drawing
 
1. A phase change memory element, comprising:
a memory region having a bulk zone and an active zone, the memory region being made of a germanium, antimony and tellurium based alloy with an average percentage of germanium in the memory region higher than 50%;
a first electrode;
a second electrode;
wherein the memory region is arranged between the first and the second electrodes;
wherein the active zone of the memory region is adjacent the first electrode and covered by the bulk zone;
wherein the active zone of the memory region is configured to switch between a first stable state associated with a first memory logic level and a second stable state associated with a second memory logic level; and
wherein the active zone of the memory region has, in the first stable state, a uniform, amorphous structure covered by the bulk zone and has, in the second stable state, a differential polycrystalline structure covered by the bulk zone, said differential polycrystalline structure comprising a first portion having a first stoichiometry and a second portion having a second stoichiometry, wherein the second stoichiometry is different from the first stoichiometry.