Method and apparatus for increasing the reliability of an access transitor coupled to a magnetic tunnel junction (MTJ)

摘要

A method of writing to a magnetic tunnel junction (MTJ) of a magnetic memory array includes an access transistor coupled to the MTJ for reading of and writing to the MTJ, where when the MTJ is written to, at times, by switching its magnetic orientation from an anti-parallel to a parallel magnetic orientation, a bit line that is coupled to one end of the MTJ is raised to Vcc and a voltage that is the sum of Vcc and Vx is applied to the gate of the access transistor, with Vx being approximately the voltage at an opposite end of the MTJ. Further, the voltage of a Source Line (SL), which is coupled to the MTJ using a first transistor of a write driver that is also coupled to the SL, is regulated such that SL remains sufficiently above 0 volts to avoid violation of Vgs exceeding Vcc where Vgs is the gate to source voltage of the access transistor.

主权项

1. A method of writing to a magnetic tunnel junction (MTJ) of a magnetic memory array of a magnetic memory system, the MTJ being coupled to an access transistor of the magnetic memory system and the MTJ having a magnetic orientation associated therewith, the MTJ being written to by switching its magnetic orientation from an anti-parallel to a parallel magnetic orientation, the method comprising:
storing the resistance value of a first MTJ of the magnetic memory array of the magnetic memory system in a data register; exchanging the information stored in the data register with information stored in a cache register, and prior to the exchanging, the cache register having stored the information that is to be written to the first MTJ; raising the voltage of a bit line (BL) to set a second MTJ to a voltage level that is the maximum voltage level for programming the second MTJ, the second MTJ and the first MTJ forming a set of MTJs; exchanging the information stored in the data register with the information stored in the cache register; depending on the value of the data in the data register, raising the voltage of the BL or a sense line (SL); reading the second MTJ; comparing the read data of the second MTJ to the information in the data register; and depending on the outcome of the comparison, declaring that the information that is to be written to the first MTJ has been written to the first MTJ successfully, or not.