# US 8,787,066 B2 · Method for forming resistive switching memory elements with improved switching behavior > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,066 B2 - Document ID: US8787066B2 - Status: Granted - Kind: B2 - Application number: 13/281,777 - Filed: 2011-10-26 - Published: 2013-05-02 - Granted: 2014-07-22 - Earliest claimed: 2011-10-26 - Assignees: Intermolecular, Inc.; Kabushiki Kaisha Toshiba; SanDisk 3D LLC - Applicants: Yun Wang; Tony Chiang; Imran Hashim; Vidyut Gopal - Inventors: Yun Wang; Tony Chiang; Imran Hashim; Vidyut Gopal - Web page: https://patentgrep.com/patent/US8787066B2 ## CPC - H10N 70/231: {based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect} - H10N 70/041: {Modification of switching materials after formation, e.g. doping (shaping H10N70/061)} - H10N 70/235: {between different crystalline phases, e.g. cubic and hexagonal} - H10N 70/826: {adapted for essentially vertical current flow, e.g. sandwich or pillar type devices} - H10N 70/8833: {Binary metal oxides, e.g. TaOx} - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract Methods for producing RRAM resistive switching elements having optimal switching behavior include crystalline phase structural changes. Structural changes indicative of optimal switching behavior include hafnium oxide phases in an interfacial region between a resistive switching layer and an electrode. ## Claims ### Claim 1 A method of operating a resistive-switching memory cell, the method comprising: providing the resistive-switching memory cell, wherein the cell comprises a first metal oxide layer between a first electrode and a second electrode; applying an electrical field to the first metal oxide layer by applying a switching voltage between the first electrode and the second electrode; wherein the electrical field changes a resistance state of the resistive-switching memory cell by changing at least one structural property of a region of the first metal oxide layer; and wherein the at least one structural property comprises at least one of crystallinity, crystal phase, silicide content, or molecular structure. ### Claim 2 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property comprises transitioning a portion of the metal oxide in the region from crystalline to amorphous or from amorphous to crystalline. ### Claim 3 (depends on 1) The method of claim 1, wherein the region is near the first electrode, and wherein the metal oxide in the region is amorphous when the resistive-switching memory cell is in a low resistance state. ### Claim 4 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property comprises transitioning a portion of the metal oxide in the region from a crystal phase having a first bandgap to a crystal phase having a second bandgap; wherein the first bandgap differs from the second bandgap. ### Claim 5 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property comprises transitioning a portion of the metal oxide in the region from one of a tetragonal, orthorhombic, monoclinic, cotunnite, or cubic crystal phase to a different one of the tetragonal, orthorhombic, monoclinic, cotunnite, or cubic crystal phase. ### Claim 6 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property comprises formation or dissociation of a silicide mass. ### Claim 7 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property comprises an increase or decrease of hafnium silicide content. ### Claim 8 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property comprises changing a portion of the metal oxide in the region to a differently structured oxide of a same metal. ### Claim 9 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property comprises converting Hf4O8 to Hf4O7 or Hf4O7 to Hf4O8. ### Claim 10 (depends on 1) The method of claim 1, wherein the switching voltage is less than or equal to 7V. ### Claim 11 (depends on 1) The method of claim 1, wherein the region comprises the entirety of the first metal oxide layer, and wherein the changing of the at least one structural property is substantially homogeneous. ### Claim 12 (depends on 1) The method of claim 1, wherein the changing of the at least one structural property occurs in a first region of the first metal oxide layer but not in a second region of the first metal oxide layer; wherein the first region comprises a top or bottom interface between the first metal oxide layer and a neighboring layer; and wherein the second region comprises a center plane of the first metal oxide layer parallel to, but not coincident with, the top or bottom interface of the first metal oxide layer. ### Claim 13 (depends on 12) The method of claim 12, wherein the neighboring layer is one of the first electrode or the second electrode. ### Claim 14 (depends on 12) The method of claim 12, wherein the neighboring layer is a second metal oxide layer. ### Claim 15 (depends on 12) The method of claim 12, wherein the neighboring layer contains silicon, and wherein the at least one structural property comprises silicide content. ### Claim 16 (depends on 12) The method of claim 12, wherein the neighboring layer is a polysilicon electrode, and wherein the at least one structural property comprises silicide content. ### Claim 17 (depends on 1) The method of claim 1, wherein the first metal oxide layer comprises both crystalline and amorphous material. ### Claim 18 (depends on 1) The method of claim 1, wherein the first metal oxide layer comprises two or more different crystal phases. ### Claim 19 (depends on 1) The method of claim 1, wherein the first metal oxide layer comprises a silicide of a same metal as the metal oxide. ### Claim 20 (depends on 1) The method of claim 1, wherein the first metal oxide layer comprises at least two different molecular structures of the metal oxide.