# US 12,225,835 B2 · Resistive switching device having a protective electrode ring > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,225,835 B2 - Document ID: US12225835B2 - Status: Granted - Kind: B2 - Application number: 17/483,868 - Filed: 2021-09-24 - Published: 2023-04-06 - Granted: 2025-02-11 - Earliest claimed: 2021-09-24 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Takashi Ando; Ruilong Xie; Alexander Reznicek; Pouya Hashemi - Web page: https://patentgrep.com/patent/US12225835B2 ## CPC - H10N 70/841: {Electrodes} - H10N 70/063: {by etching of pre-deposited switching material layers, e.g. lithography} - H10N 70/20: Multistable switching devices, e.g. memristors - H10N 70/8833: {Binary metal oxides, e.g. TaOx} - H10B 63/80: {Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays} - H10N 70/826: {adapted for essentially vertical current flow, e.g. sandwich or pillar type devices} - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - H10B: ELECTRONIC MEMORY DEVICES ## Abstract Embodiments of the invention are directed to a structure that includes a resistive switching device (RSD). The RSD includes a first terminal having an outer sidewall surface; a second terminal; an active region having a switchable conduction state; and a first protective layer on the outer sidewall surface of the first terminal. ## Claims ### Claim 1 A structure comprising: a resistive switching device (RSD) comprising: a first terminal having an outer sidewall surface; a second terminal; an active region having a switchable conduction state; an undercut region at least partially defined by the outer sidewall surface and a portion of a top surface of the active region; and a first protective layer within the undercut region. ### Claim 2 (depends on 1) The structure of claim 1, wherein the first protective layer is on the outer sidewall surface of the first terminal. ### Claim 3 (depends on 2) The structure of claim 2, further comprising a first via trench formed above the first terminal, wherein the first terminal comprises a first terminal material having a first etch rate to an etching substance used to form the first via trench. ### Claim 4 (depends on 3) The structure of claim 3, wherein the first protective layer comprises a first protective layer material having a second etch rate to the etching substance used to form the first via trench. ### Claim 5 (depends on 4) The structure of claim 4, wherein the first etch rate of the first terminal material is greater than the second etch rate of the first protective layer material. ### Claim 6 (depends on 5) The structure of claim 5 further comprising a spacer layer on at least a portion of outer sidewalls of the first protective layer. ### Claim 7 (depends on 6) The structure of claim 6, wherein the spacer layer comprises a spacer layer material having a third etch rate to the etching substance used to form the first via trench. ### Claim 8 (depends on 7) The structure of claim 7, wherein the third etch rate of the spacer layer material is greater than the second etch rate of the first protective layer material. ### Claim 9 (depends on 5) The structure of claim 5 further comprising: a second protective layer formed on outer sidewalls of the second terminal, wherein the second terminal comprises a second terminal material having a first etch rate to an etching substance used to form the first via trench; and wherein the second protective layer comprises a second protective layer material having a second etch rate to the etching substance used to form the first via trench. ### Claim 10 (depends on 9) The structure of claim 9, wherein the first etch rate of the second terminal material is greater than the second etch rate of the second protective layer material. ### Claim 11 A method of forming a structure, the method comprising: forming a resistive switching device (RSD) comprising: a first terminal; a first terminal undercut region at least partially defined by an outer sidewall surface of the first terminal; a second terminal; an active region having a switchable conduction state; and a first protective layer within the first terminal undercut region. ### Claim 12 (depends on 11) The method of claim 11, wherein the first protective layer is on the outer sidewall surface of the first terminal. ### Claim 13 (depends on 12) The method of claim 12 further comprising forming a first via trench above the first terminal, wherein the first terminal comprises a first terminal material having a first etch rate to an etching substance used to form the first via trench. ### Claim 14 (depends on 13) The method of claim 13, wherein the first protective layer comprises a first protective layer material having a second etch rate to the etching substance used to form the first via trench. ### Claim 15 (depends on 14) The method of claim 14, wherein the first etch rate of the first terminal material is greater than the second etch rate of the first protective layer material. ### Claim 16 (depends on 15) The method of claim 15 further comprising forming a spacer layer on at least a portion of outer sidewalls of the first protective layer. ### Claim 17 (depends on 16) The method of claim 16, wherein the spacer layer comprises a spacer layer material having a third etch rate to the etching substance used to form the first via trench. ### Claim 18 (depends on 17) The method of claim 17, wherein the third etch rate of the spacer layer material is greater than the second etch rate of the first protective layer material. ### Claim 19 (depends on 15) The method of claim 15 further comprising: forming a second protective layer on outer sidewalls of the second terminal, wherein the second terminal comprises a second terminal material having a first etch rate to an etching substance used to form the first via trench; and wherein the second protective layer comprises a second protective layer material having a second etch rate to the etching substance used to form the first via trench. ### Claim 20 (depends on 19) The method of claim 19, wherein the first etch rate of the second terminal material is greater than the second etch rate of the second protective layer material.