# US 8,570,792 B2 · Magnetoresistive random access memory > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,792 B2 - Document ID: US8570792B2 - Status: Granted - Kind: B2 - Application number: 13/356,920 - Filed: 2012-01-24 - Published: 2013-07-25 - Granted: 2013-10-29 - Earliest claimed: 2012-01-24 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Tien-Wei Chiang; Kai-Chun Lin; Ya-Chen Kao; Hung-Chang Yu - Inventors: Tien-Wei Chiang; Kai-Chun Lin; Ya-Chen Kao; Hung-Chang Yu - Web page: https://patentgrep.com/patent/US8570792B2 ## CPC - H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices - G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell} - G11C 11/1659: {Cell access} - G11C 11/1675: {Writing or programming circuits or methods} - H10N 50/10: Magnetoresistive devices - H10B: ELECTRONIC MEMORY DEVICES - G11C: STATIC STORES (semiconductor memory devices H10B) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A magnetoresistive random access memory (MRAM) cell includes a magnetic tunnel junction (MTJ), a top electrode disposed over the MTJ, a bottom electrode disposed below the MTJ, and an induction line disposed above or below the MTJ. The induction line is configured to induce a magnetic field at the MTJ. ## Claims ### Claim 1 A magnetoresistive random access memory (MRAM) cell, comprising: a magnetic tunnel junction (MTJ); a top electrode disposed over the MTJ; a bottom electrode disposed below the MTJ; and an induction line disposed above or below the MTJ, wherein the induction line is configured to induce a magnetic field at the MTJ, and wherein the induction line includes an arch shaped portion for inducing the magnetic field at the MTJ. ### Claim 2 (depends on 1) The MRAM cell of claim 1, wherein the induction line is disposed directly over or underneath the MTJ. ### Claim 3 (depends on 1) The MRAM cell of claim 1, wherein the induction line is disposed to one side of the MTJ. ### Claim 4 (depends on 1) The MRAM cell of claim 1, further comprising a second induction line configured to induce a magnetic field at the MTJ. ### Claim 5 (depends on 1) The MRAM cell of claim 1, wherein the induction line is formed in a different layer than the top electrode, if disposed above the MTJ and in a different layer than the bottom electrode, if disposed below the MTJ. ### Claim 6 (depends on 1) The MRAM cell of claim 1, wherein the MTJ comprises a free layer, a fixed layer, and an insulator disposed between the free layer and the fixed layer, the fixed layer having a fixed magnetic polarity, and the free layer has a changeable magnetic polarity. ### Claim 7 (depends on 1) The MRAM cell of claim 1, wherein the MTJ has an oval or elliptical shape. ### Claim 8 (depends on 1) The MRAM cell of claim 1, wherein the MRAM cell is a spin transfer torque (STT) MRAM cell. ### Claim 9 A magnetoresistive random access memory MRAM cell array write circuit comprising: a plurality of MRAM cells arranged in an array of rows and columns, each MRAM cell comprising a magnetic tunnel junction (MTJ), a top electrode disposed over the MTJ, a bottom electrode disposed below the MTJ; at least one induction line disposed with respect to each of two columns of MRAM cells, each induction line configured to induce a magnetic field at the MTJs with respect to which it is disposed; and at least one current source for providing current to the at least one induction line, wherein the at least one induction line includes only one induction line per two columns of MRAM cells, each column of MRAM cells having only one induction line disposed in connection with it. ### Claim 10 (depends on 9) The MRAM cell array write circuit of claim 9, the at least one current sources comprises a current source for providing current to a plurality of induction lines and a plurality of switches for selectively coupling the current source to the plurality of induction lines. ### Claim 11 (depends on 9) The MRAM cell array circuit of claim 9, wherein the at least one current source comprises a plurality of current sources coupled to a plurality of corresponding induction lines. ### Claim 12 A magnetoresistive random access memory (MRAM) cell, comprising: a magnetic tunnel junction (MTJ) having an oval or elliptical shape having short (X) and long (Y) axes; a top electrode disposed over the MTJ; a bottom electrode disposed below the MTJ; and an induction line disposed above or below the MTJ, wherein the induction line includes an arch shaped portion configured to induce a magnetic field at the MTJ. ### Claim 13 (depends on 12) The MRAM cell of claim 12, wherein the arched shaped portion is disposed between a pair of straight portions of the induction line disposed in line with one another, the straight portions being oriented generally parallel to the long (Y) axis of the MTJ. ### Claim 14 (depends on 12) The MRAM cell of claim 12, wherein the arched shaped portion is disposed between a pair of straight portions of the induction line disposed in line with one another, the straight portions being oriented generally parallel to the short (X) axis of the MTJ. ### Claim 15 (depends on 12) The MRAM cell of claim 12, wherein the arch shaped portion is disposed to induce a magnetic field at the MTJ perpendicular to both the short (X) and long (Y) axes of the MTJ. ### Claim 16 (depends on 12) The MRAM cell of claim 12, wherein at least a portion of the induction line is disposed directly over or underneath the MTJ. ### Claim 17 (depends on 1) The MRAM cell of claim 1, wherein the MTJ has a long axis (Y) and an short axis (X), and the arch shaped portion is oriented to induce a magnetic field at the MTJ perpendicular to both the short (X) and long (Y) axes of the MTJ. ### Claim 18 A magnetoresistive random access memory (MRAM) cell array write circuit comprising: a plurality of MRAM cells arranged in an array of rows and columns, each MRAM cell comprising a magnetic tunnel junction (MTJ), a top electrode disposed over the MTJ, a bottom electrode disposed below the MTJ; at least one induction line disposed with respect to each of two columns of MRAM cells, each induction line configured to induce a magnetic field at the MTJs with respect to which it is disposed; and at least one current source for providing current to the at least one induction line, wherein the at least one induction line includes a pair of induction lines disposed at opposite sides of the MTJs of each individual column of MTJs, and wherein current from the at least one current source flows in the same direction through the pair of induction lines during a write operation.