Phase change memory device for multibit storage

Abstract

A phase change memory device (10) having a heater element (2) and memory region (3) of chalcogenic material. The memory region has a phase changing portion (5) in electrical and thermal contact with the heater element and forms a first current path between the heater element and a rest portion (4) of the memory element. The phase changing portion (5) has a dimension correlated to information stored in the memory region and a higher resistivity than the rest portion (4). A parallel current path (11) extends between the heater element (2) and the rest portion (4) of said memory element and has a resistance depending upon the dimension of the phase changing portion (5) and lower than the phase changing portion (5), thus modulating the overall resistance of phase change memory device.

Description

technical field

[0001] The invention relates to a phase-change storage device for multi-bit storage. Background technique

[0002] As we know, phase-change memory devices use phase-change materials. The so-called phase-change materials are for electronic storage applications, which can be electrically switched between a generally amorphous state and a generally crystalline state, or between a completely amorphous state and a completely Materials that switch electrically between different detectable localized ordered states in the full range between crystalline states. The state of the phase change material is also non-volatile, specifically, when setting the indicated resistance value in the crystalline state, semi-crystalline state, amorphous state or semi-amorphous state, since the value represents the phase or physical state (for example, crystalline or amorphous), so the value remains unchanged until changed by another programming event. The state is not affected by re...

Images