Phase-change nonvolatile memory and manufacturing method therefor

摘要

A phase-change nonvolatile memory (PRAM) is constituted of a semiconductor substrate, a lower electrode, a first interlayer insulating film having a first hole, an impurity diffusion layer embedded in the first hole, a second interlayer insulating film having a second hole whose diameter is smaller than the diameter of the first hole, a phase-change recording layer, and an upper electrode. The impurity diffusion layer is constituted of two semiconductor layers having different conductivity types, wherein one semiconductor layer is constituted of a base portion and a projecting portion having a heating spot in contact with the phase-change recording layer, while the other semiconductor layer is formed to surround the projecting portion. A depletion layer is formed in proximity to the junction surface so as to reduce the diameter of the heating spot, thus reducing the current value Ireset for writing data in to the phase-change recording layer.

主权项

1. A phase-change nonvolatile memory comprising:
a semiconductor substrate; a lower electrode formed on the semiconductor substrate; a first interlayer insulating film which is formed to cover the lower electrode and the semiconductor substrate, wherein a first hole is formed in the first insulating film so as to expose the lower electrode; an impurity diffusion layer embedded in the first hole, wherein the impurity diffusion layer is constituted of a first semiconductor layer and a second semiconductor layer which have different conductivity types; a second interlayer insulating film which is formed to cover the first interlayer insulating film and the impurity diffusion layer, wherein a second hole is formed in the second interlayer insulating film so as to expose the impurity diffusion layer; a phase-change recording layer which is formed to cover the second interlayer insulating film and to embed the second hole; and an upper electrode formed on the phase-change recording layer, wherein the first semiconductor layer is constituted of a base portion which is formed inside the first hole so as to cover the lower electrode and a projecting portion which projects from the base portion so that a heating spot thereof comes in contact with the phase-change recording layer in the second hole, while the second semiconductor layer is formed to at least partially surround the projecting portion, wherein a depletion layer is formed in proximity to a junction surface formed between the first semiconductor layer and the second semiconductor layer so as to reduce a diameter of the heating spot, and wherein the heating spot heats the phase-change recording layer in response to a current flowing between the impurity diffusion layer and the phase-change recording layer.