Superlattice phase change thin film with low density change, phase change memory and preparation method thereof

Abstract

The invention discloses a superlattice phase change thin film with low density change, a phase change memory and a preparation method. The superlattice phase change thin film comprises a first phase change layer and a second phase change layer which are alternately stacked to form a periodic structure, in the crystallization process, the first phase change layer has conventional positive density change, and the second phase change layer has abnormal negative density change, so that the density of the second phase change layer is reduced abnormally in the crystallization process, the size of the second phase change layer is increased, and the size reduction phenomenon of the first phase change layer in the crystallization process can be counteracted; the superlattice film formed by alternately stacking the conventional phase change material and the material with negative density change can reduce the size change of the phase change storage material in the phase change process, thereby reducing cavities caused by repeated increase and decrease of the size of the phase change storage material in the cyclic erasing and writing process; when the superlattice phase change thin film withlow density or even zero density change is applied to a phase change memory, the stability of cyclic erasing and writing of the phase change memory device can be remarkably improved, and the service life of the device is prolonged.

Description

technical field [0001] The invention belongs to the technical field of microelectronic devices and memories, and more specifically relates to a low-density variable superlattice phase-change film, a phase-change memory and a preparation method. Background technique [0002] Phase-change memory materials have attracted much attention because they can quickly achieve reversible transformation between a crystalline state (low resistance state) and an amorphous state (high resistance state) by applying electricity or light pulses. The process of the low resistance state is called the SET process, and its reverse process is called the RESET process. Storage technology based on phase-change materials is considered to be one of the strong competitors of next-generation storage technology. [0003] The two states of phase change materials have different mass densities. Generally speaking, the crystalline state has higher density and smaller volume due to the orderly arrangement of ...

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Problems solved by technology

At present, the two types of phase change layer materials in superlattice phase change materials also have the characteristics of large changes in the two-state density, resulting in "voids" in the process of repeated erasing and writing. Therefore, superlattice phase change materials still have multiple cycles of erasure. The problem of device failure after writing

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