Phase change memory cell sidewall heater
A phase change memory structure with improved sidewall heater and formation thereof may be presented. Phase change materials are capable of being switched between a first structural state in which the material is in a generally amorphous solid phase, and a second structural state in which the material is in a generally crystalline solid phase in the active region of the cell. Presented herein may be a side wall heater, where the upper section extends through bilayer dielectric to contact a phase change material layer and the lower section of the sidewall heater has conductive layers in contact with the bottom electrode. The width of the sidewall heater may reflect an inverted T shape reducing the current requirement to reset the phase change material.
1 . A phase change memory element structure, comprising:
a bottom electrode;
a phase change material layer;
a bilayer dielectric, including a base layer dielectric and a phase change element layer dielectric located on top of the base layer dielectric; and
a sidewall heater with an upper section and a lower section, wherein the upper section extends vertically through the phase change element layer dielectric of the bilayer dielectric to contact the phase change material layer and the lower section of the sidewall heater has a plurality of conductive layers in contact with the bottom electrode, and wherein a dimension of the upper section of the sidewall heater in contact with the phase change material layer is substantially smaller than a dimension of the lower section of the sidewall heater in contact with the bottom electrode, resulting in an inverted T-shape,
wherein the sidewall heater is composed of a multilayer stack of metal including alternating layers of at least two materials selected from the group consisting of TiN, TaN, TaAlN, TiSiN, TiAlN, and TaSiN.
2 . The phase change memory element structure of claim 1 , wherein the phase change memory element structure is formed on a semiconductor substrate.
3 . The phase change memory element structure of claim 1 , wherein a configuration of the multilayer stack of metal is selected from the group consisting of 3 nm TaN/5 nm TiN and 3 nm TaN/3 nm TiN.
4 . The phase change memory element structure of claim 1 , wherein the bilayer dielectric is comprised of a bottom layer of dielectric of SiN and a top layer of dielectric SiO 2 .
5 . The phase change memory element structure of claim 1 , wherein the phase change material layer is comprised of a chalcogenide glass.
6 . The phase change memory element structure of claim 5 , wherein the chalcogenide glass is germanium-antimony-tellurium (“GST”).
7 . A phase change memory element structure, comprising:
a bottom electrode;
a phase change material layer;
a bilayer dielectric, including a base layer dielectric and a phase change element layer dielectric located on top of the base layer dielectric; and
a sidewall heater with an upper section and a lower section, wherein the upper section extends vertically through the phase change element layer dielectric of the bilayer dielectric to contact the phase change material layer and the lower section of the sidewall heater has a plurality of conductive layers in contact with the bottom electrode and wherein a width of the upper section of the sidewall heater in contact with the phase change material layer is substantially smaller than a width of the lower section of the sidewall heater in contact with the bottom electrode,
wherein the sidewall heater is composed of a multilayer stack of metal including alternating layers of at least two materials selected from the group consisting of TiN, TaN, TaAlN, TiSiN, TiAlN, and TaSiN.
8 . The phase change memory element structure of claim 7 , wherein the upper section of the sidewall heater is comprised of a single layer of conductive material.
9 . The phase change memory element structure of claim 7 , further comprising a SiN liner surrounding the sidewall heater with an exception of a portion in contact with the phase change material layer.