# US 2010/0163818 A1 · Forming a carbon passivated ovonic threshold switch > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0163818 A1 - Document ID: US20100163818A1 - Status: Published application - Kind: A1 - Application number: 12/346,705 - Filed: 2008-12-30 - Published: 2010-07-01 - Earliest claimed: 2008-12-30 - Assignees: STMicroelectronics S.r.l. - Inventors: Jinwook Lee; Kuo-wei Chang; Jason S. Reid; Wim Y. Deweerd; Aleshandre M. Diaz - Web page: https://patentgrep.com/patent/US20100163818A1 ## CPC - H10B 63/24: {of the Ovonic threshold switching type} - H10N 70/041: {Modification of switching materials after formation, e.g. doping (shaping H10N70/061)} - H10N 70/066: {by filling of openings, e.g. damascene method} - H10N 70/20: Multistable switching devices, e.g. memristors - H10N 70/231: {based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect} - H10N 70/801: {Constructional details of multistable switching devices} - H10N 70/826: {adapted for essentially vertical current flow, e.g. sandwich or pillar type devices} - H10N 70/8413: {adapted for resistive heating} - H10N 70/882: {Compounds of sulfur, selenium or tellurium, e.g. chalcogenides} - Y10S 438/90: Bulk effect device making - H10B: ELECTRONIC MEMORY DEVICES - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract By making an ovonic threshold switch using a carbon interfacial layer having a thickness of less than or equal to ten percent of the thickness of the associated electrode, cycle endurance may be improved. In some embodiments, a glue layer may be used between the carbon and the chalcogenide of the ovonic threshold switch. The glue layer may be effective to improve adherence between carbon and chalcogenide. ## Claims ### Claim 1 An ovonic threshold switch comprising: a first electrode having a thickness; an ovonic threshold switching material; a first carbon layer between said first electrode and said ovonic threshold switch material, said first carbon layer having a thickness of less than ten percent of the thickness of said first electrode. ### Claim 2 (depends on 1) The switch of claim 1 wherein said first carbon layer and said first electrode are under said ovonic threshold switching material. ### Claim 3 (depends on 2) The switch of claim 2 including a second carbon layer and a second electrode over said ovonic threshold switching material. ### Claim 4 (depends on 1) The switch of claim 1 including a glue layer adhering the carbon layer to said first electrode. ### Claim 5 (depends on 4) The switch of claim 4 wherein said glue layer includes one of titanium, titanium nitride, and titanium aluminum nitride. ### Claim 6 (depends on 1) The switch of claim 1 wherein carbon is ion mixed into the ovonic threshold switching material, forming a graded contact. ### Claim 7 (depends on 1) The switch of claim 1 wherein the first carbon layer includes silicon carbide. ### Claim 8 (depends on 1) The switch of claim 1 wherein said first carbon layer includes amorphous material. ### Claim 9 (depends on 1) The switch of claim 1 wherein said first carbon layer has a thickness of about 5 to about 10 nm. ### Claim 10 (depends on 1) The switch of claim 1 wherein said ovonic threshold switching material is an amorphous chalcogenide. ### Claim 11 A method comprising: forming an ovonic threshold switch, including: forming a first electrode having a thickness; forming ovonic threshold switching material; and forming a first carbon layer between said first electrode and said ovonic threshold switching material such that said first carbon layer has a thickness of less than or equal to ten percent of the thickness of said first electrode. ### Claim 12 (depends on 11) The method of claim 11 including forming said first electrode and said first carbon layer under said ovonic threshold switching material. ### Claim 13 (depends on 12) The method of claim 12 including forming a second carbon layer and a second electrode over said ovonic threshold switching material. ### Claim 14 (depends on 11) The method of claim 11 including forming a glue layer between said first carbon layer and said first electrode. ### Claim 15 (depends on 11) The method of claim 11 including ion mixing carbon into said ovonic threshold switching material to form a graded contact. ### Claim 16 (depends on 11) The method of claim 11 including forming said ovonic threshold switching material of amorphous chalcogenide. ### Claim 17 (depends on 11) The method of claim 11 including forming said first carbon layer with a thickness of between about 5 and about 10 nm. ### Claim 18 (depends on 11) The method of claim 11 including forming an ovonic unified memory coupled to the ovonic threshold switch using said chalcogenide material over an ovonic unified memory. ### Claim 19 (depends on 11) The method of claim 11 wherein said first electrode, said ovonic threshold switching material, and said first carbon layer are planar, stacked layers. ### Claim 20 A system comprising: a processor; and an ovonic threshold switch coupled to said processor, said ovonic threshold switch including a first electrode, a ovonic threshold switching material, and a first carbon layer between said first electrode said ovonic threshold switching material, said first carbon layer having a thickness of less than ten percent of a thickness of said first electrode. ### Claim 21 (depends on 20) The system of claim 20 wherein said first carbon layer and said first electrode are under said ovonic threshold switching material and said ovonic threshold switch includes a second carbon layer and a second electrode over said ovonic threshold switching material. ### Claim 22 (depends on 20) The system of claim 20 wherein said first carbon layer has a thickness of about 5 to about 10 nm. ### Claim 23 (depends on 20) The system of claim 20 including a glue layer adhering the first carbon layer to said first electrode. ### Claim 24 (depends on 23) The system of claim 23 wherein said glue layer includes one of titanium, titanium nitride, and titanium aluminum nitride. ### Claim 25 (depends on 20) The system of claim 20 wherein carbon is ion mixed into the ovonic threshold switching material, forming a graded contact. ### Claim 26 (depends on 20) The system of claim 20 including a phase change memory, said memory including said switch and an underlying ovonic unified memory.