Intermolecular, Inc.

Kabushiki Kaisha Toshiba

Sandisk 3d LLC

Mihir Tendulkar

Yun Yu Wang

Imran Hashim

Takeshi Yamaguchi

Tim Minvielle

Randall Higuchi

Chien-Lan Hsueh

David Chi

Milind Ganesh Weling

Embodiments of the invention include a method of forming a nonvolatile memory device that contains a resistive switching memory element with improved device switching performance and lifetime, due to the addition of a current limiting component. In one embodiment, the current limiting component comprises a resistive material configured to improve the switching performance and lifetime of the resistive switching memory element. The electrical properties of the current limiting layer are configured to lower the current flow through the variable resistance layer during the logic state programming steps by adding a fixed series resistance in the resistive switching memory element found in the nonvolatile memory device. In one embodiment, the current limiting component comprises a tunnel oxide layer that is a current limiting material and an oxygen barrier layer that is an oxygen deficient material disposed within a resistive switching memory element in a nonvolatile resistive switching memory device.

Nonvolatile memory device using a tunnel oxide layer and oxygen blocking layer as a current limiter element

In a thin-film resistor stack (e.g. A ReRAM embedded resistor), a metallic barrier layer 1-5 nm thick protects an underlying or overlying ternary metal nitride layer from unwanted oxidation while having negligible effect on the resistance or height of the stack. For devices subjected to temperatures over 650 C after forming the stack, the metallic barrier layer may be iridium or ruthenium. For devices with temperatures kept below 650 C after forming the stack, the metallic barrier layer may be Al. The metallic barrier layer(s) and the ternary nitride layer may be formed in situ, for example by sputtering or atomic layer deposition.

Conductive barriers for ternary nitride thin-film resistors

Ternary metal nitride layers suitable for thin-film resistors are fabricated by forming constituent layers of complementary components (e.g., binary nitrides of the different metals, or a binary nitride of one metal and a metallic form of the other metal), then annealing the constituent layers to interdiffuse the materials, thus forming the ternary metal nitride. The constituent layers (e.g., 2-5 nm thick) may be sputtered from binary metal nitride targets, from metal targets in a nitrogen-containing ambient, or from metal targets in an inert ambient. Optionally, a nitrogen-containing ambient may also be used for the annealing. The annealing may be 10 seconds to 10 minutes at 500-1000&#xb0; C. and may also process another component on the same substrate (e.g., activate a diode).

Ternary metal nitride formation by annealing constituent layers

Provided are memory cells, such as resistive random access memory (ReRAM) cells, and methods of fabricating such cells. A cell includes an embedded resistor and resistive switching layer connected in series within the embedded resistor. 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. The embedded resistor includes a stoichiometric nitride that has a bandgap of less than 2 eV. The embedded resistor is configured to maintain a substantially constant resistance throughout fabrication and operation of the cell, such as annealing the cell and subjecting the cell to forming and switching signals. The stoichiometric nitride may be one of hafnium nitride, zirconium nitride, or titanium nitride. The embedded resistor may also include a dopant, such as tantalum, niobium, vanadium, tungsten, molybdenum, or chromium.

Doped narrow band gap nitrides for embedded resistors of resistive random access memory cells

A nonvolatile memory device and method for forming a resistive switching memory element, with improved lifetime and switching performance. A nonvolatile memory element includes resistive switching layer formed between a first and second electrode. The resistive switching layer comprises a metal oxide. One or more electrodes include a dopant material to provide the electrode with enhanced oxygen-blocking properties that maintain and control the oxygen ion content within the memory element contributing to increased device lifetime and performance.

Doped electrodes used to inhibit oxygen loss in ReRAM device

Provided are test vehicles for evaluating various semiconductor materials. These materials may be used for various integrated circuit components, such as embedded resistors of resistive random access memory cells. Also provided are methods of fabricating and operating these test vehicles. A test vehicle may include two stacks protruding through an insulating body. Bottom ends of these stacks may include n-doped poly-silicon and may be interconnected by a connector. Each stack may include a titanium nitride layer provided over the poly-silicon end, followed by a titanium layer over the titanium nitride layer and a noble metal layer over the titanium layer. The noble metal layer extends to the top surface of the insulating body and forms a contact surface. The titanium layer may be formed in-situ with the noble metal layer to minimize oxidation of the titanium layer, which is used as an adhesion and oxygen getter.

Test vehicles for evaluating resistance of thin layers

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

Embodiments of the invention include a nonvolatile memory device that contains nonvolatile resistive random access memory device with improved device performance and lifetime. In some embodiments, nonvolatile resistive random access memory device includes a diode, a metal silicon nitride embedded resistor, and a resistive switching layer disposed between a first electrode layer and a second electrode layer. In some embodiments, the method of forming a resistive random access memory device includes forming a diode, forming a metal silicon nitride embedded resistor, forming a first electrode layer, forming a second electrode layer, and forming a resistive switching layer disposed between the first electrode layer and the second electrode layer.

Method of forming anneal-resistant embedded resistor for non-volatile memory application

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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Embodiments of the invention generally include a method of forming a nonvolatile memory device that contains a resistive switching memory element that has improved device switching performance and lifetime, due to the addition of a current limiting component disposed therein. The electrical properties of the current limiting component are configured to lower the current flow through the variable resistance layer during the logic state programming steps by adding a fixed series resistance in the resistive switching memory element of the nonvolatile memory device. In one embodiment, the current limiting component comprises a tunnel oxide that is a current limiting material disposed within a resistive switching memory element in a nonvolatile resistive switching memory device. 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.

Nonvolatile memory device using a tunnel oxide as a passive current steering element

Embodiments of the invention include a method of forming a nonvolatile memory device that contains a resistive switching memory element that has improved device switching performance and lifetime, due to the addition of a current limiting component disposed therein. The electrical properties of the current limiting component are configured to lower the current flow through the variable resistance layer during the logic state programming steps by adding a fixed series resistance in the resistive switching memory element of the nonvolatile memory device. In some embodiments, the current limiting component comprises a varistor that is a current limiting material disposed within a resistive switching memory element in a nonvolatile resistive switching memory device. 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.

Nonvolatile memory device using a varistor as a current limiter element

Provided are ReRAM cells, each having at least one interface between an electrode and a resistive switching layers with a maximum field value of less than 0.25. The electrode materials forming such interfaces include tantalum nitrides doped with lanthanum, aluminum, erbium yttrium, or terbium (e.g., Ta(Dopant)N, where X is at least about 0.95). The electrode materials have low work functions (e.g., less than about 4.5 eV). At the same time, the resistive switching materials have high relative dielectric permittivities (e.g., greater than about 30) and high electron affinities (greater than about for 3.5 eV). Niobium oxide is one example of a suitable resistive switching material. Another electrode interfacing the resistive switching layer may have different characteristics and, in some embodiments, may be an inert electrode.

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Mountain View, CA, United States of America

Mihir Tendulkar