Non-volatile resistive-switching memories

#The present invention relates generally to electronic memories. More specifically, non-volatile resistive-switching memories are described.

#Non-volatile memories are semiconductor memories that retain their contents when unpowered. Non-volatile memories are used for storage in electronic devices such as digital cameras, cellular telephones, and music players, as well as in general computer systems, embedded systems and other electronic devices that require persistent storage. Non-volatile semiconductor memories can take the form of removable and portable memory cards or other memory modules, can be integrated into other types of circuits or devices, or can take any other desired form. Non-volatile semiconductor memories are becoming more prevalent because of their advantages of small size and persistence, having no moving parts, and requiring little power to operate.

#Flash memory is a common type of non-volatile memory used in a variety of devices. Flash memory uses an architecture that can result in long access, erase, and write times. The operational speeds of electronic devices and storage demands of users are rapidly increasing. Flash memory is proving, in many instances, to be inadequate for non-volatile memory needs. Additionally, volatile memories (such as random access memory (RAM)) can potentially be replaced by non-volatile memories if the speeds of non-volatile memories are increased to meet the requirements for RAM and other applications currently using volatile memories.

#Various embodiments of the invention are disclosed in the following detailed description and the accompanying drawings:

#FIG. 1 illustrates a memory array of resistive switching memory elements;

#FIG. 2A is a logarithm of current (I) versus voltage (V) plot for a memory element;

#A detailed description of one or more embodiments is provided below along with accompanying figures. The detailed description is provided in connection with such embodiments, but is not limited to any particular example. The scope is limited only by the claims and numerous alternatives, modifications, and equivalents are encompassed. Numerous specific details are set forth in the following description in order to provide a thorough understanding. These details are provided for the purpose of example and the described techniques may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the embodiments has not been described in detail to avoid unnecessarily obscuring the description.

#According to various embodiments, resistive-switching memory elements can be formed that use bulk-mediated switching mechanisms. According to some of these embodiments, a metal-insulator-metal (MIM) memory element can be formed from two electrodes and one or more layers of one or more metal oxides disposed therebetween. A bulk switching mechanism, as used herein, describes changes in resistivity that are caused by events (e.g., the filling or emptying of defects) within the bulk of the metal oxide. In these embodiments, defects such as traps can be formed or enhanced in the metal oxide. The defects are filled to form non-metallic percolation paths by applying a set voltage pulse and emptied to break the percolation paths by applying a reset voltage pulse. The percolation paths formed during the set operation increase the conductivity of the metal oxide, thereby reducing the resistivity of the metal oxide and the memory element. The change in resistivity can be read at another voltage to determine the contents of the memory element. Materials for the metal oxide(s) and electrodes can be selected to enhance the characteristics of the memory element.

#Some memory elements described herein may include a single layer of metal oxide that has certain characteristics, such as high bandgap, low leakage, bulk-switching properties, and a scalable (e.g., thickness dependent) set voltage. Other memory elements may include multiple layers of metal oxide and/or dopants to enhance or change the characteristics of the memory element. Additionally, at least one electrode of the memory element may be a noble or near noble metal.