Crossbar, Inc.

Cypress Semiconductor Corporation

Sundar Narayanan

Natividad Vasquez

Krishnaswamy Ramkumar

Harry Yue Gee

Zhen Gu

Steve Maxwell

Steven Patrick Maxwell

Sung Hyun Jo

Tanmay Kumar

Alain Paul Blosse

Yunyu Wang

Prabhuram Gopalan

Wee Chen Gan

Mehdi Asnaashari

Wei Ti Lee

Hanna Bamnolker

Shahin Sharifzadeh

Alex Kabansky

Sung-Hyun Jo

Vinay Krishna

Biju Parameshwaran

Chidambaram G Kallingal

Liang Zhao

Hean-Cheal Lee

Majid Milani

Fabrication of resistive switching memory devices is herein provided. By way of example, a method for a two-step etch for fabricating a non-volatile resistive memory device is disclosed. In another example, a method for a three-step etch for fabricating a non-volatile resistive memory device is provided. Still other embodiments disclose a method for fabricating a non-volatile metal nitrogen/metal oxygen resistive switching memory device. Further embodiments disclose a method for fabricating a volatile resistive switching selector device. Processes for forming protective spacers in conjunction with fabricating a disclosed resistive memory device are also provided.

Resistive switching memory devices and method(s) for forming the resistive switching memory devices

Resistive switching memory cells having filament-based switching mechanisms are provided. By way of example, resistive switching memory cells having resistive filaments constrained to a core of the cell are disclosed. In other examples, methods for fabricating resistive switching memory cells to constrain a conductive filament formed in the resistive switching memory cell to a central portion of core of the cell are disclosed.

Resistive switching memory having confined filament formation and methods thereof

A two-terminal resistive switching device (TTRSD) such as a non-volatile two-terminal memory device or a volatile two-terminal selector device can be formed according to a manufacturing process. The process can include forming an etch stop layer that is made of aluminum and can include forming a buffer layer below the etch stop layer and/or between the etch stop layer and a top electrode of the TTRSD.

Using aluminum as etch stop layer

A self-aligned memory device includes a conductive bottom plug disposed within an insulating layer and having a coplanar top surface, a self-aligned planar bottom electrode disposed upon the coplanar top surface and having a thickness within a range of 50 Angstroms to 200 Angstroms, a planar switching material layer disposed upon the self-aligned planar bottom electrode, a planar active metal material layer disposed upon the planar switching material layer and a planar top electrode disposed above the planar active metal material layer, wherein the self-aligned planar bottom electrode, the planar switching material layer, the planar active metal material layer, and the planar top electrode form a pillar-like structure above the insulating layer.

Resistive random access memory and fabrication techniques

Two-terminal memory devices can be formed in dielectric material that is electrically insulating and operates as a blocking layer to mitigate diffusion of material from a metal layer. A stack of layers of the two-terminal memory device can be covered with a liner layer that can comprise the dielectric material. Thus, in some implementations, the liner layer and the blocking layer can have a similar etch rate.

Memory stack liner comprising dielectric block layer material

Provision of fabrication, construction, and/or assembly of a two-terminal memory device is described herein. The two-terminal memory device can include an active region with a silicon bearing layer, an interface layer, and an active metal layer. The interface layer can be grown on the silicon bearing layer, and the growth of the interface layer can be regulated with NO plasma.

Regulating interface layer formation for two-terminal memory

Two-terminal memory devices can be formed in part within a dielectric material that is electrically insulating and operates as a blocking layer to mitigate diffusion of metal particles employed in integrated circuit fabrication. This dielectric material can be protected from other fabrication processes corrosive to the dielectric material (e.g., CMP, HF clean, etc) by a silicon containing liner. Use of the silicon containing liner can enable a minimum thickness of the dielectric material to be preserved and can facilitate step height differences between adjacent material surfaces that form a two-terminal memory device to be on the order of less than about five angstroms. This small step height difference, particularly when underlying a switching layer of the two-terminal memory device, can yield excellent switching characteristics.

Liner layer for dielectric block layer

Providing for a memory device having a resistive switching memory integrated within backend layers of the memory device is described herein. By way of example, the resistive switching memory can be embedded memory such as cache, random access memory, or the like, in various embodiments. The resistive memory can be fabricated between various backend metallization schemes, including backend copper metal layers and in part utilizing one or more damascene processes. In some embodiments, the resistive memory can be fabricated in part with damascene processes and in part with subtractive etch processing, utilizing four or fewer photo-resist masks. Accordingly, the disclosure provides a relatively low cost, high performance embedded memory compatible with a variety of fabrication processes of integrated circuit foundries.

Integrative resistive memory in backend metal layers

A memory cell that includes a first metal layer formed over a substrate is provided. The substrate includes one or more complementary metal-oxide semiconductor devices. The memory cell also includes a via device that connects at least a portion of the first metal layer and at least another portion of a second metal layer. The first metal layer has a first thickness having an edge thereof that serves as an electrode for a memory cell formed by the via device. The memory cell scales as a function of the first thickness and at least in part independent of a minimum feature size of the memory device.

Scalable silicon based resistive memory device

A recessed high voltage metal oxide semiconductor (MOS) transistor is provided for use in a two-terminal memory cell. The two-terminal memory cell can include a resistive switching device connected to the recessed MOS transistor. The recessed MOS transistor provides for an increased channel length relative to the transistor size in comparison to a traditional MOS transistor. This allows for a decreased memory cell size while maintaining comparable electrical parameters (threshold voltage, channel length, and leakage) than would otherwise be possible. The recessed MOS transistor can be made as either a NMOS or PMOS device using n-type or p-type materials respectively, where the channel, or inversion layer, is formed by electrons (NMOS) or holes (PMOS) between the source and drain in the transistor.

Recessed high voltage metal oxide semiconductor transistor for RRAM cell

Provided is a monolithic integration of resistive memory with complementary metal oxide semiconductor using integrated circuit foundry processes. A memory device is provided that includes a substrate comprising one or more complementary metal-oxide semiconductor devices, a first insulator layer formed on the substrate; and a monolithic stack. The monolithic stack includes multiple layers fabricated as part of a monolithic process over the first insulator layer. The multiple layers include a first metal layer, a second insulator layer, and a second metal layer. A resistive memory device structure is formed within the second insulator layer and within a thermal budget of the one or more complementary metal-oxide semiconductor devices. The resistive memory device structure is implemented as a pillar device or as a via device. Further, the first metal layer is coupled to the second metal layer.

Monolithically integrated resistive memory using integrated-circuit foundry compatible processes

A two-terminal memory device can be formed according to a manufacturing process that utilizes two distinct chemical-mechanical planarization (CMP) processes for each of bottom electrode/terminal (BE) and the top electrode/terminal (TE). The CMP processes can reduce planar height variations for a top surface of the BE and a top surface of the TE. The CMP processes can reduce height differences between the top surface of the BE and adjacent dielectric surfaces and reduce height differences between the top surface of the TE and adjacent dielectric surfaces.

Flatness of memory cell surfaces

Providing for a monolithic memory device comprising a combination of a one-transistor, one-resistor (1T1R) memory array, and a one-transistor, multiple-resistor (1TnR, where n is a suitable integer greater than 1) memory array is described herein. By way of example, the monolithic memory device can be a stand-alone device, configured to perform functions in response to predetermined conditions and generate an output(s), or can be a removable device that can be connected to and operable with another device. In various embodiments, the 1TnR array having high memory density can serve as storage class memory (SCM) for the monolithic memory device, and the 1T1R array having high performance and efficacy can serve as code memory. In addition to the foregoing, the 1T1R array and the 1TnR array can be fabricated from at least one common layer or a common processing step, to simplify and lower cost of fabricating disclosed memory devices.

Growing community of inventors

Cupertino, CA, United States of America

Sundar Narayanan