Magnetic tunnel junction based chip identification

• US 9,569,712 B1
• Filed: 05/27/2016
• Issued: 02/14/2017
• Est. Priority Date: 12/15/2015
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Annunziata, Anthony J., Kothandaraman, Chandrasekharan, Trouilloud, Philip L.
• Primary Examiner(s): Nguyen, Viet Q
• Application Number:
  US15/166,981
• Time in Patent Office: 263 Days
• Field of Search: 365/171, 365/158, 365/148
• US Class Current: 1/1
• CPC Class Codes: G06F 21/44 Program or device authentication
• CPC Class Codes: G06K 19/06196 Constructional details
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/1695 Protection circuits or methods
• CPC Class Codes: H03K 19/003 Modifications for increasing the reliability for protection
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details

Abstract

The present invention provides integrated circuit chips having chip identification aspects. The chips include magnetic tunnel junction (MTJ) structures, and more specifically, include permanent bit strings used for chip identification and/or authentication. Systems and processes for chip identification are also disclosed herein. The MTJ element structures provided herein can have a defined resistance profile such that the intrinsic variability of the MTJ element structure is used to encode and generate a bit string that becomes a fingerprint for the chip. In some embodiments, an oxygen treatment covering all or a selected portion of an array of MTJ elements can be used to create a mask or secret key that can be used and implemented to enhance chip identification.

Claims

1. A method of generating a fingerprint for an array of a plurality of MTJ elements, the method comprising:

sensing a first MTJ element by subjecting the first MTJ element in the plurality of MTJ elements to a voltage to generate data for the first element in the plurality of the MTJ elements relative to a first reference data and provide a first sensed MTJ element;

sensing a second MTJ element by subjecting the second MTJ element in the plurality of MTJ elements to a voltage to generate data for the second element in the plurality of the MTJ elements relative to a second reference data and provide a second sensed MTJ element;

continuing to sequentially sense a predetermined number of MTJ elements in the array of the plurality of MTJ elements by sequentially subjecting subsequent MTJ elements in the array of the plurality of MTJ elements to a voltage to generate data for the subsequent MTJ elements in the array of the plurality of MTJ elements relative to a respective sequential reference data for each of the MTJ elements being sensed and provide a predetermined number of sensed MTJ elements; and

collecting the generated data for the sensed MTJ elements to generate a permanent string of the data associated with the array of the MTJ elements, wherein a portion or all of the permanent string of data for the MTJ array comprises an oxygen mask.

2. The method of claim 1, wherein the array of the MTJ elements comprises part of an MRAM device.

3. The method of claim 1, wherein the sensing comprises single ended sensing or differential sensing.

4. The method of claim 3, wherein the sensing comprises single ended sensing.

5. The method of claim 4, wherein the single ended sensing is current based sensing.

6. The method of claim 4, wherein the single ended sensing is voltage based sensing.

7. The method of claim 4, wherein the single ended sensing comprises comparing a current flowing through the first MTJ element, the second MTJ element, or the subsequent MTJ elements against a voltage of an external reference value.

8. The method of claim 3, wherein the sensing comprises differential sensing.

9. The method of claim 8, wherein the differential sensing comprises comparing a first voltage, wherein the first voltage is a voltage of the first MTJ element, the second MTJ element, or the subsequent MTJ elements against a second voltage, wherein the second voltage is a voltage of a reference MTJ element.

10. The method of claim 1, comprising generating resistance data for one or more of the first element, the second element, and the subsequent MTJ elements.

11. The method of claim 1, comprising assigning a value to the first MTJ element, wherein the value indicates whether the first MTJ element is within a predetermined range of the first reference data.

12. The method of claim 1, comprising assigning a value to the second MTJ element, wherein the value indicates whether the first MTJ element is within a predetermined range of the second reference data.

13. The method of claim 1, comprising assigning values to the subsequent MTJ elements, wherein the values indicate whether the subsequent MTJ elements are within a predetermined range of the sequential reference data.

14. The method of claim 1, wherein all of the permanent string of data for the MTJ array comprises an oxygen mask.

15. The method of claim 1, wherein the oxygen mask alters the resistance profile of one or more of the MTJ elements in the array of the MTJ elements.

16. The method of claim 1, comprising authenticating a chip using the permanent string of data associated with the array of the MTJ elements.

17. The method of claim 1, comprising identifying a chip using the permanent string of data associated with the array of the MTJ elements.

18. The method of claim 1, wherein the permanent string of the data comprises resistance data of the plurality of MTJ elements.

19. The method of claim 1, wherein the array of the MTJ elements comprises part of a memory device.