Intermolecular, Inc.

Kabushiki Kaisha Toshiba

Sandisk 3d LLC

Randall Higuchi

Chien-Lan Hsueh

Vidyut Gopal

Imran Hashim

Yun Yu Wang

Takeshi Yamaguchi

Tim Minvielle

Jinhong Tong

Mihir Tendulkar

Hieu T Pham

Zhendong Hong

Robert A Huertas

Tony P Chiang

Federico Nardi

Albert Sanghyup Lee

Ryan C Clarke

Brian Butcher

Methods for producing RRAM resistive switching elements having reduced forming voltage include doping to create oxygen deficiencies in the dielectric film. Oxygen deficiencies in a dielectric film promote formation of conductive pathways.

Method for forming a doped metal oxide for use in resistive switching memory elements

Provided are methods of fabricating memory cells such as resistive random access memory (ReRAM) cells. A method involves forming a first layer including two high-k dielectric materials such that one material has a higher dielectric constant than the other material. In some embodiments, hafnium oxide and titanium oxide form the first layer. The higher-k material may be present at a lower concentration. In some embodiments, a concentration ratio of these two high-k materials is between about 3 and 7. The first layer may be formed using atomic layer deposition. The first layer is then annealed in an oxygen-containing environment. The method may proceed with forming a second layer including a low-k dielectric material, such as silicon oxide, and forming an electrode. After forming the electrode, the memory cell is annealed in a nitrogen containing environment. The nitrogen anneal may be performed at a higher temperature than the oxygen anneal.

Doped oxide dielectrics for resistive random access memory cells

Provided are resistive random access memory (ReRAM) cells having switching layers that include hafnium, aluminum, oxygen, and nitrogen. The composition of such layers is designed to achieve desirable performance characteristics, such as low current leakage as well as low and consistent switching currents. In some embodiments, the concentration of nitrogen in a switching layer is between about 1 and 20 atomic percent or, more specifically, between about 2 and 5 atomic percent. Addition of nitrogen helps to control concentration and distribution of defects in the switching layer. Also, nitrogen as well as a combination of two metals helps with maintaining this layer in an amorphous state. Excessive amounts of nitrogen reduce defects in the layer such that switching characteristics may be completely lost. The switching layer may be deposited using various techniques, such as sputtering or atomic layer deposition (ALD).

Resistive switching layers including Hf-Al-O

Embodiments of the invention generally relate to nonvolatile memory devices and methods for manufacturing such memory devices. The methods for forming improved memory devices, such as a ReRAM cells, provide optimized, atomic layer deposition (ALD) processes for forming a metal oxide film stack which contains at least one hard metal oxide film (e.g., metal is completely oxidized or substantially oxidized) and at least one soft metal oxide film (e.g., metal is less oxidized than hard metal oxide). The soft metal oxide film is less electrically resistive than the hard metal oxide film since the soft metal oxide film is less oxidized or more metallic than the hard metal oxide film. In one example, the hard metal oxide film is formed by an ALD process utilizing ozone as the oxidizing agent while the soft metal oxide film is formed by another ALD process utilizing water vapor as the oxidizing agent.

Atomic layer deposition of metal oxides for memory applications

Compound layers, such as metal silicon nitrides, are formed by ALD or CVD from precursors with incompatible reaction temperature ranges. The substrate is held at a temperature within the lower reaction temperature range (e.g., that of a metal precursor). The low-temperature precursor and its reactant react to form an ALD monolayer or thin CVD layer. The high-temperature precursor and its reactant are pulsed in the chamber, and the substrate is irradiated with ultraviolet light. The ultraviolet light adds energy to the system to overcome the reaction barrier despite the substrate temperature being below the minimum reaction temperature of the high-temperature precursor.

Low-temperature deposition of nitrides by UV-assisted ALD or CVD

A method of fabricating a resistive random access memory (ReRAM) cell may include forming a set of nanolaminate structures over an electrode, such that each structure includes at least one first element oxide layer and at least one second element oxide layer. The overall set is operable as a resistive switching layer in a ReRAM cell. In this set, an average atomic ratio of the first element to the second element is different in at least two nanolaminate structures. This ratio may be less in nanolaminate structures that are closer to electrodes than in the middle nanolaminate structures. Alternatively, this ratio may increase from one end of the set to another. The first element may be less electronegative than the second elements. The first element may be hafnium, while the second element may be one of zirconium, aluminum, titanium, tantalum, or silicon.

Controlling composition of multiple oxides in resistive switching layers using atomic layer deposition

A nonvolatile memory device contains a resistive switching memory element with improved device switching performance and lifetime by custom tailoring the average concentration of defects in the resistive switching film and methods of forming the same. The nonvolatile memory element includes a first electrode layer, a second electrode layer, and a resistive switching layer disposed between the first electrode layer and the second electrode layer. The resistive switching layer comprises a first sub-layer and a second sub-layer, wherein the first sub-layer has more defects than the first sub-layer. A method includes forming a first sub-layer on the first electrode layer by a first ALD process and forming a second sub-layer on the first sub-layer by a second ALD process, where the first sub-layer has a different amount of defects than the second sub-layer.

Using saturated and unsaturated ALD processes to deposit oxides as ReRAM switching layer

A nonvolatile resistive memory element includes a novel switching layer and methods of forming the same. The switching layer includes a material having bistable resistance properties and formed by bonding silicon to oxygen or nitrogen. The switching layer may include at least one of SiO, SiON, or SiN. Advantageously, the SiO, SiON, and SiNgenerally remain amorphous after thermal anneal processes are used to form the devices, such as ReRAM devices.

Nonvolatile resistive memory element with a silicon-based switching layer

Forming a resistive switching layer having a vertical interface can generate defects confined along the interface between two electrodes. The confined defects can form a pre-determined region for filament formation and dissolution, leading to low power resistive switching and low program voltage or current variability. In addition, the filament forming process of the resistive memory device can be omitted due to the existence of the confined defects.

Vertical oxide-oxide interface for forming-free, low power and low variability RRAM devices

Provided are resistive random access memory (ReRAM) cells and methods of fabricating thereof. A ReRAM cell includes an embedded resistor and resistive switching layer connected in series. The embedded resistor prevents excessive electrical currents through the resistive switching layer, especially when the resistive switching layer is switched into its low resistive state, thereby preventing over-programming. The embedded resistor includes aluminum, nitrogen, and one or more additional metals (other than aluminum). The concentration of each component is controlled to achieve desired resistivity and stability of the embedded resistor. In some embodiments, the resistivity ranges from 0.1 Ohm-centimeter to 40 Ohm-centimeter and remains substantially constant while applying an electrical field of up 8 mega-Volts/centimeter to the embedded resistor. The embedded resistor may be made from an amorphous material, and the material is operable to remain amorphous even when subjected to typical annealing conditions.

Metal aluminum nitride embedded resistors for resistive random memory access cells

Provided are resistive random access memory (ReRAM) cells and methods of fabricating thereof. A ReRAM cell includes an embedded resistor and a resistive switching layer connected in series with this resistor. The resistor is configured to prevent over-programming of the cell by limiting electrical currents through the resistive switching layer. Unlike the resistive switching layer, which changes its resistance in order to store data, the embedded resistor maintains a substantially constant resistance during operation of the cell. The embedded resistor is formed from tantalum nitride and silicon nitride. The atomic ratio of tantalum and silicon may be specifically selected to yield resistors with desired densities and resistivities as well as ability to remain amorphous when subjected to various annealing conditions. The embedded resistor may also function as a diffusion barrier layer and prevent migration of components between one of the electrodes and the resistive switching layer.

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San Jose, CA, United States of America

Randall Higuchi