System and method for writing data to magnetoresistive random access memory cells
View Patent ↗Magnetic random access memory (MRAM) cell with a thermally assisted switching writing procedure and methods for manufacturing and using same. The MRAM cell includes a magnetic tunnel junction that has at least a first magnetic layer, a second magnetic layer, and an insulating layer disposed between the first and a second magnetic layers. The MRAM cell further includes a select transistor and a current line electrically connected to the junction. The current line advantageously can support a plurality of MRAM operational functions. The current line can fulfill a first function for passing a first portion of current for heating the junction and a second function for passing a second portion of current in order to switch the magnetization of the first magnetic layer.
1. A method of writing data in a magnetic random access memory (MRAM) cell with a thermally assisted switching (TAS) writing procedure, the MRAM cell including a magnetic tunnel junction and a select transistor, the magnetic tunnel junction having a first magnetic layer, a second magnetic layer, and an insulating layer disposed between the first and second magnetic layers, the select transistor being coupled with the magnetic tunnel junction and controllable via a word line, a current line electrically connected to the magnetic tunnel junction and passing a first portion of current for heating the magnetic tunnel junction and a second portion of current for switching a magnetization of the first magnetic layer, the method comprising:
passing the first portion of current through the magnetic tunnel junction via the current line to heat the magnetic tunnel junction;
passing the second portion of current through the current line to switch the magnetization of the storage layer;
after the magnetic tunnel junction has reached a predetermined high temperature threshold, turning off the first portion of current to cool the magnetic tunnel junction; and
after the magnetic tunnel junction has cooled down to a predetermined low temperature threshold current, turning off the second portion of current.
2. The method according to claim 1 , wherein said passing the second portion of current includes passing the second portion of current that comprises a field current for generating a magnetic field for switching the magnetization of the first magnetic layer.
3. The method according to claim 1 , wherein said passing the second portion of current includes passing the second portion of current that comprises a spin polarized write current for inducing magnetic switching of the first magnetic layer.
4. The method according to claim 1 , wherein said passing the first portion of current and said passing the second portion of current are performed simultaneously.
5. The method according to claim 1 , wherein said passing the first portion of current is performed before said passing the second portion of current.
6. The method according to claim 5 , wherein said passing the second portion of current and said turning off the first portion of current are performed simultaneously.
7. The method according to claim 1 , wherein said passing the second portion of current is performed before said passing the first portion of current.
8. The method according to claim 1 , wherein the first portion of current is controlled by the voltage of the word line when the select transistor is operated in a conducting mode.
9. The method according to claim 1 , wherein the current line has a finite resistance, said resistance being used to limit or regulate the second portion of current.
10. A method of writing data in a magnetic random access memory (MRAM) cell with a thermally assisted switching (TAS) writing procedure, the MRAM cell including a magnetic tunnel junction and a select transistor, the magnetic tunnel junction having a first magnetic layer, a second magnetic layer, and an insulating layer disposed between the first and second magnetic layers, the select transistor being coupled with the magnetic tunnel junction and controllable via a word line, a current line electrically connected to the magnetic tunnel junction and passing a first portion of current for heating the magnetic tunnel junction and a second portion of current for switching a magnetization of the first magnetic layer, the method comprising:
passing the first portion of current through the magnetic tunnel junction via the current line to heat the magnetic tunnel junction;
passing the second portion of current through the current line to switch the magnetization of the storage layer;
after the magnetic tunnel junction has reached a predetermined high temperature threshold, turning off the first portion of current to cool the magnetic tunnel junction; and
after the magnetic tunnel junction has cooled down to a predetermined low temperature threshold current, turning off the second portion of current,
wherein said passing the second portion of current is performed before said passing the first portion of current.
11. The method according to claim 10 , wherein the first portion of current is controlled by the voltage of the word line when the select transistor is operated in a conducting mode.
12. The method according to claim 10 , wherein the current line has a finite resistance, said resistance being used to limit or regulate the second portion of current.