Doped electrodes used to inhibit oxygen loss in ReRAM device

#This invention relates to nonvolatile memory elements, and more particularly, to methods for forming resistive switching memory elements used in nonvolatile memory devices.

#Nonvolatile memory elements are used in systems in which persistent storage is required. For example, digital cameras use nonvolatile memory cards to store images and digital music players use nonvolatile memory to store audio data. Nonvolatile memory is also used to persistently store data in computer environments.

#Nonvolatile memory is often formed using electrically-erasable programmable read only memory (EEPROM) technology. This type of nonvolatile memory contains floating gate transistors that can be selectively programmed or erased by application of suitable voltages to their terminals.

#So that the manner in which the above recited features can be understood in detail, a more particular description may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.

#FIG. 1 is a perspective view of a memory array of memory devices.

#FIG. 2A is a schematic cross-sectional view of a memory device.

#While the foregoing description is directed to particular embodiments, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

#Embodiments according to the invention generally include a method of forming a nonvolatile memory device that contains a resistive switching memory element that has an improved device switching performance and an increased usable lifetime. Embodiments provide a metal-insulator-metal (MIM) stack structure that maintains and controls the localized oxygen content and location over the lifetime of the device. It is noted that relative directional terms used herein with regard to embodiments described are for purposes of description only, and do not limit its configuration as would be understood by a person skilled in the art. Specifically, directional terms such as “over,” “above,” “under,” and the like are used under the assumption that substrate 201 on which embodiments are formed is a “bottom” element and is therefore “under” elements of the structures formed thereon.

#In some embodiments, a nonvolatile memory element includes a resistive switching layer formed between a first metal electrode layer and a second metal electrode layer. At least one electrode layer is doped with a dopant material so as to inhibit oxygen diffusion within the MIM device in a particular direction. For example, typical electrode materials such as titanium nitride (TiN), tantalum nitride (TaN), platinum (Pt), gold (Au), ruthenium (Ru), iridium (Ir), among others may include a dopant material such as beryllium (Be). For example, beryllium binds with the base material along the grain boundaries of the selected electrode material and blocks the oxygen in the resistive switching layer from diffusing out of the resistive switching layer and into and through the electrode. Maintaining the oxygen content within the MIM structure enhances the data retention and lifetime (endurance) of the memory element.