Bipolar multistate nonvolatile memory

摘要

Embodiments generally include a method of forming a nonvolatile memory device that contains a resistive switching memory element that has an improved device switching capacity by using multiple layers of variable resistance layers. In one embodiment, the resistive switching element comprises at least three layers of variable resistance materials to increase the number of logic states. Each variable resistance layer may have an associated high resistance state and an associated low resistance state. As the resistance of each variable resistance layer determines the digital data bit that is stored, the multiple variable resistance layers per memory element allows for additional data storage without the need to further increase the density of nonvolatile memory devices. Typically, resistive switching memory elements may be formed as part of a high-capacity nonvolatile memory integrated circuit, which can be used in various electronic devices, such as digital cameras, mobile telephones, handheld computers, and music players.

主权项

1. A method of fabricating a multistate nonvolatile memory element, the method comprising:
forming a first layer operable as a first variable resistance layer; forming a second layer operable as a second variable resistance layer over the first layer; and forming a third layer operable as a third variable resistance layer over the second layer; wherein the first layer is connected in series with the second layer and the second layer is connected in series with the third layer; wherein the first layer is configured to switch between a first low resistance state and a first high resistance state; wherein the second layer is configured to switch between a second low resistance state and a second high resistance state; wherein the third layer is configured to switch between a third low resistance state and a third high resistance state; wherein each of the first layer, the second layer, and the third layer comprises one of hafnium oxide, tantalum oxide, aluminum oxide, lanthanum oxide, yttrium oxide, dysprosium oxide, ytterbium oxide, lutetium oxide, lanthanum aluminum oxide, lanthanum lutetium oxide, or zirconium oxide; and wherein the multistate nonvolatile memory element has at least four different stable resistance states.