# US 8,772,748 B2 · Semiconductor memory device using variable resistance element or phase-change element as memory device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,772,748 B2 - Document ID: US8772748B2 - Status: Granted - Kind: B2 - Application number: 13/772,699 - Filed: 2013-02-21 - Published: 2013-06-27 - Granted: 2014-07-08 - Earliest claimed: 2009-12-17 - Assignees: Kabushiki Kaisha Toshiba - Applicants: Kabushiki Kaisha Toshiba - Inventors: Nobuaki Yasutake - Web page: https://patentgrep.com/patent/US8772748B2 ## CPC - H10B 63/20: {comprising selection components having two electrodes, e.g. diodes} - G11C 13/0004: {comprising amorphous/crystalline phase transition cells} - H10B 63/84: {arranged in a direction perpendicular to the substrate, e.g. 3D cell arrays} - H10N 70/063: {by etching of pre-deposited switching material layers, e.g. lithography} - H10N 70/20: Multistable switching devices, e.g. memristors - H10N 70/826: {adapted for essentially vertical current flow, e.g. sandwich or pillar type devices} - H10N 70/883: {Oxides or nitrides} - H10N 70/8845: {Carbon or carbides} - G11C 2213/71: Three dimensional array - G11C 2213/72: Array wherein the access device being a diode - H10B: ELECTRONIC MEMORY DEVICES - G11C: STATIC STORES (semiconductor memory devices H10B) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A semiconductor memory device includes a first conductive line, a second conductive line, a cell unit, a silicon nitride film and a double-sidewall film. The first conductive line extends in a first direction. The second conductive line extends in a second direction crossing the first direction. The cell unit includes a phase-change film and a rectifier element connected in series with each other between the first conductive line and the second conductive line. The silicon nitride film is formed on a side surface of the phase-change film. The double-sidewall film includes a silicon oxide film and the silicon nitride film formed on a side surface of the rectifier element. ## Claims ### Claim 1 A semiconductor memory device comprising: a first conductive line extending in a first direction; a second conductive line extending in a second direction crossing the first direction; a cell unit including a phase-change film and a rectifier element connected in series with each other between the first conductive line and the second conductive line; a silicon nitride film formed on an all side surface of the phase-change film in a plane in which the silicon nitride film and the phase-change film are cut in parallel with the first direction and the second direction; and a double-sidewall film including a silicon oxide film and the silicon nitride film formed on an all side surface of the rectifier element in a plane in which the double-sidewall film and the rectifier element are cut in parallel with the first direction and the second direction, wherein the silicon oxide film is in contact with the side surface of the rectifier element, and the silicon nitride film is in direct contact with the side surface of the phase-change film and is in direct contact with the silicon oxide film on the side surface of the rectifier element. ### Claim 2 (depends on 1) The semiconductor memory device according to claim 1, wherein the rectifier element and the phase-change film are cut along a plane parallel to the first direction and the second direction, and a sectional area of the rectifier element is smaller than a sectional area of the phase-change film. ### Claim 3 (depends on 1) The semiconductor memory device according to claim 1, further comprising: a coating oxide film formed between the cell units to isolate the cell units from each other. ### Claim 4 (depends on 1) The semiconductor memory device according to claim 1, wherein the rectifier element includes an amorphous epitaxial layer. ### Claim 5 (depends on 1) The semiconductor memory device according to claim 1, further comprising: a first electrode layer formed between the first conductor line and the rectifier element; and a second electrode layer formed between the rectifier element and the phase-change film. ### Claim 6 (depends on 5) The semiconductor memory device according to claim 5, wherein the silicon oxide film has bird's beaks on a contact surface to the first electrode layer and a contact surface to the second electrode layer. ### Claim 7 (depends on 1) The semiconductor memory device according to claim 1, further comprising: a control circuit connected to the first conductive line and the second conductive line, wherein the control circuit, without changing polarity of a voltage applied to the phase-change film, controls a magnitude and an application time of the voltage to reversibly change resistance of the phase-change film between at least a first value and a second value. ### Claim 8 (depends on 1) The semiconductor memory device according to claim 1, wherein the rectifier element includes a p-i-n diode configured by a p-type semiconductor layer, an n-type semiconductor layer, and an intrinsic semiconductor layer arranged between the p-type semiconductor layer and the n-type semiconductor layer. ### Claim 9 (depends on 1) The semiconductor memory device according to claim 1, wherein the silicon oxide film expands to an outside of a side surface of the rectifier element. ### Claim 10 (depends on 1) The semiconductor memory device according to claim 1, wherein the cell unit is a rectangle in a plane in which the cell unit is cut in parallel with the first direction and the second direction. ### Claim 11 (depends on 10) The semiconductor memory device according to claim 10, wherein the silicon nitride film formed on the all side surface of the phase-change film is formed at a time on two parallel sides in the rectangle. ### Claim 12 (depends on 10) The semiconductor memory device according to claim 10, wherein the silicon oxide film formed on the all side surface of the phase-change film is formed at a time on two parallel sides in the rectangle. ### Claim 13 (depends on 10) The semiconductor memory device according to claim 10, wherein the silicon nitride film of the double-sidewall film is continuously formed in a direction in which the phase-change film and the rectifier element are stacked, and the silicon nitride film formed on the all side surface of the phase-change film is formed at a time on two parallel sides in the rectangle. ### Claim 14 (depends on 1) The semiconductor memory device according to claim 1, wherein a portion of the silicon oxide film of the double-sidewall film is arranged under the phase-change film in a direction in which the phase-change film and the rectifier element are stacked. ### Claim 15 (depends on 1) The semiconductor memory device according to claim 1, wherein the silicon nitride film of the double-sidewall film is continuously formed in a direction in which the phase-change film and the rectifier element are stacked.