CN-115862702-B - MRAM device and method for determining external magnetic field and influence thereof

Abstract

A Magnetoresistive Random Access Memory (MRAM) device and method of determining the external magnetic field and influence thereof are provided. The MRAM device includes a main Magnetic Tunnel Junction (MTJ) array including a plurality of memory cells configured to store memory data and a reference MTJ array including a plurality of reference cells having MTJ structures. The MRAM device also includes a controller operatively associated with the primary MTJ array and the reference MTJ array. The controller is configured to receive a total resistance of the reference MTJ array in relation to the strength of the external magnetic field, determine whether the external magnetic field is fatal based on the received total resistance of the reference MTJ array and a predetermined threshold, and provide a notification indicating that memory data stored in the main MTJ array is not authentic if it is determined that the external magnetic field surrounding the MRAM device is fatal.

Inventors

• ZHUANG XUELI
• LI YUANREN
• JIANG DIANWEI
• SHI YIJUN

Assignees

• 台湾积体电路制造股份有限公司

Dates

Publication Date

20260508

Application Date

20220708

Priority Date

20220420

Claims (20)

1. 1. A method implemented by a controller of determining an external magnetic field effect of an MRAM device operatively associated with the controller, the method comprising: Providing an MRAM device comprising a magnetic tunnel junction array comprising a plurality of memory cells and a reference magnetic tunnel junction array comprising a plurality of reference cells, wherein the plurality of memory cells and the plurality of reference cells are together formed within an interconnect structure disposed over a substrate, the plurality of reference cells each having a smaller lateral dimension than the plurality of memory cells; reading or writing memory data stored in the array of magnetic tunnel junctions; detecting a reference magnetic tunnel junction array signal from the reference magnetic tunnel junction array; Comparing the reference magnetic tunnel junction array signal with a predetermined threshold value, and If the reference magnetic tunnel junction array signal exceeds the predetermined threshold, a notification signal is provided indicating that the memory data is not authentic.
2. 2. The method of claim 1, wherein the lateral dimension of the reference cell is 70% to 90% of the lateral dimension of the memory cell.
3. 3. The method of claim 1, wherein the reference cells each have a lateral dimension 5nm to 10nm smaller than the memory cells.
4. 4. The method of claim 1, wherein a plurality of reference cells each have the same composition as the plurality of memory cells.
5. 5. The method of claim 1, wherein the predetermined threshold is determined by performing a test procedure that provides an external magnetic field having a threshold strength that has a fatal effect on the MRAM device.
6. 6. The method of claim 1, wherein the predetermined threshold is retrieved from memory.
7. 7. An MRAM device, comprising: a main magnetic tunnel junction array comprising a plurality of memory cells configured to store memory data; a reference magnetic tunnel junction array comprising a plurality of reference cells having a magnetic tunnel junction structure, wherein the plurality of reference cells of the reference magnetic tunnel junction array each have a smaller lateral dimension than the plurality of memory cells of the main magnetic tunnel junction array, and A controller operatively associated with the array of main magnetic tunnel junctions and the array of reference magnetic tunnel junctions, wherein the controller is configured to: receiving a total resistance of the reference magnetic tunnel junction array in relation to an external magnetic field strength; Determining whether the external magnetic field is fatal based on the received total resistance of the reference magnetic tunnel junction array and a predetermined threshold value, and If it is determined that the external magnetic field surrounding the MRAM device is fatal, a notification is provided that indicates that the memory data stored in the array of main magnetic tunnel junctions is not authentic.
8. 8. The MRAM device of claim 7, wherein the plurality of reference cells of the reference magnetic tunnel junction array each have a same composition as the plurality of memory cells of the main magnetic tunnel junction array.
9. 9. The MRAM device of claim 7, wherein a lateral dimension of the reference cell is 70% to 90% of a lateral dimension of the memory cell.
10. 10. The MRAM device of claim 7, wherein the plurality of memory cells of the main magnetic tunnel junction array each comprise a magnetic tunnel junction structure coupled to a selector, and wherein a selector is not present in the reference magnetic tunnel junction array.
11. 11. The MRAM device of claim 7, wherein a top electrode or a bottom electrode of the magnetic tunnel junction structure of the reference magnetic tunnel junction array is connected to a reference line configured to convey a total resistance of the reference magnetic tunnel junction array.
12. 12. The MRAM device of claim 11, wherein the reference cells of the reference magnetic tunnel junction array are in series with each other and connected to the reference line.
13. 13. The MRAM device of claim 11, wherein the reference cells of the reference magnetic tunnel junction array are parallel to each other and connected to the reference line.
14. 14. The MRAM device of claim 7, wherein the reference cells each have a lateral dimension that is 5nm to 10nm smaller than the memory cells.
15. 15. The MRAM device of claim 7, wherein the reference array of magnetic tunnel junctions is disposed within an interconnect structure over a substrate.
16. 16. A method implemented by a controller of determining an external magnetic field around an MRAM device operatively associated with the controller, the MRAM device comprising a magnetic tunnel junction array comprising a plurality of memory cells and a reference magnetic tunnel junction array comprising a plurality of reference cells, wherein the plurality of reference cells each have a smaller lateral dimension than the plurality of memory cells, the method comprising: reading or writing memory data stored in the array of magnetic tunnel junctions; detecting a reference magnetic tunnel junction array signal from the reference magnetic tunnel junction array; Comparing the reference magnetic tunnel junction array signal with a predetermined threshold value, and If the reference magnetic tunnel junction array signal exceeds the predetermined threshold, a notification signal is provided indicating that the memory data is not authentic.
17. 17. The method of claim 16, wherein detecting the reference magnetic tunnel junction array signal from the reference magnetic tunnel junction array comprises: initializing a total resistance of the reference magnetic tunnel junction array by setting the plurality of memory cells of the reference magnetic tunnel junction array to a first state, and A change in resistance of the reference magnetic tunnel junction array is detected, the change in resistance being related to the strength of the external magnetic field.
18. 18. The method of claim 16, wherein the method further comprises applying an initialization bias to the reference magnetic tunnel junction array to reset the plurality of reference cells for a next detection of the external magnetic field.
19. 19. The method of claim 16, wherein the predetermined threshold is determined by performing a test procedure that provides the external magnetic field with a threshold strength that has a fatal effect on the MRAM device.
20. 20. The method of claim 16, wherein the predetermined threshold is retrieved from memory.

Description

MRAM device and method for determining external magnetic field and influence thereof Technical Field Embodiments of the present invention relate to MRAM devices and methods of determining their external magnetic fields and effects. Background Many modern electronic devices include electronic memory. The electronic memory may be volatile memory or non-volatile memory (NVM). Nonvolatile memory is capable of storing data without power, whereas volatile memory is incapable. Magnetoresistive Random Access Memory (MRAM) is a promising candidate for the next generation of non-volatile memory technology because of its relatively simple and compact structure and compatibility with Complementary Metal Oxide Semiconductor (CMOS) logic fabrication processes. Disclosure of Invention According to one aspect of an embodiment of the present invention, there is provided a method implemented by a controller of determining an effect of an external magnetic field of a Magnetoresistive Random Access Memory (MRAM) device operatively associated with the controller, the method comprising reading memory data and error correction redundancy corresponding to the memory data from the MRAM device, determining a bit error rate by performing an Error Correction Code (ECC) check based on the memory data and the error correction redundancy, the bit error rate indicating a retention failure rate of the MRAM device, comparing the retention failure rate to a predetermined failure rate threshold, and providing a notification signal indicating that the retention failure memory data is not authentic if the retention failure rate is greater than the failure rate threshold. According to one aspect of an embodiment of the present invention, there is provided a Magnetoresistive Random Access Memory (MRAM) device comprising a main Magnetic Tunnel Junction (MTJ) array comprising a plurality of memory cells configured to store memory data, a reference MTJ array comprising a plurality of reference cells having MTJ structures, and a controller operatively associated with the main MTJ array and the reference MTJ array, wherein the controller is configured to receive a total resistance of the reference MTJ array in relation to an external magnetic field strength, determine whether the external magnetic field is fatal based on the received total resistance of the reference MTJ array and a predetermined threshold, and provide a notification indicating that the memory data stored in the main MTJ array is not authentic if it is determined that the external magnetic field surrounding the MRAM device is fatal. According to one aspect of an embodiment of the present invention, there is provided a controller-implemented method of determining an external magnetic field around a Magnetoresistive Random Access Memory (MRAM) device operatively associated with the controller, the MRAM device comprising a Magnetic Tunnel Junction (MTJ) array, the MTJ array comprising a plurality of memory cells and a reference MTJ array, the reference MTJ array comprising a plurality of reference cells, the method comprising reading or writing memory data stored in the MTJ array, detecting a reference MTJ array signal from the reference MTJ array, comparing the reference MTJ array signal to a predetermined threshold, and providing a notification signal indicating that the memory data is not authentic if the reference MTJ array signal exceeds the predetermined threshold. Drawings The various aspects of the invention are best understood from the following detailed description when read in connection with the accompanying drawings. It should be emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale and are used for illustration purposes only. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. FIG. 1 illustrates a block diagram showing an MRAM device configured to detect an external magnetic field by processing data read from an MTJ array in accordance with some embodiments. FIG. 2 illustrates a flow chart showing a method of detecting an external magnetic field of an MRAM device by processing data read from an MTJ array in accordance with some embodiments. Fig. 3 illustrates a block diagram showing an MRAM device configured to detect an external magnetic field by processing data read from a reference MTJ array according to some additional embodiments. Fig. 4 illustrates a flow chart showing a method of detecting an external magnetic field of an MRAM device by processing data read from a reference MTJ array according to some additional embodiments. Fig. 5A illustrates a block diagram showing an MRAM device configured to detect an external magnetic field by processing data from a reference MTJ array, in accordance with some additional embodiments. FIG. 5B illustrates an example plot of resistance of a reference MTJ array responsive to an external magnetic field strength