A puf generating device based on mram and a puf generating method based thereon

Abstract

The application provides a MRAM-based PUF generating device and a MRAM-based PUF generating method based on the same. The MRAM-based PUF generating device is composed of a PUF data array and a PUF data reading circuit. The PUF data array is initialized by a first initialization magnetic field, so that the magnetic moment direction of the pinning layer in each PUF data unit is magnetized to a first direction. Then, the PUF data array is initialized by a second initialization magnetic field, so that the magnetic moment direction of the pinning layer in each PUF data unit is randomly flipped from the first direction to a second direction. By controlling the random flipping of the pinning layer, the random writing probability of each PUF data unit is more conveniently controlled.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a PUF generation device based on MRAM and a PUF generation method based thereon. Background Technology

[0002] Currently, most physically unclonable functions (PUFs) based on magnetic tunnel junctions (MTJs) rely on the flipping probability of the free layer in the MTJ, aiming for a 50% random probability. Specifically, an MTJ consists of a free layer (FL), a tunnel layer, a reference layer (RL), and a pinning layer (PL). The pinning layer (PL) is used to pin the magnetic moment direction of the reference layer. When using MTJs for storage, the parallel alignment (P-state) and antiparallel alignment (AP-state) of the magnetic moments between the free layer and the reference layer represent binary "0" and "1," respectively. The different magnetoresistances of the MTJ in different states are used to achieve data retrieval. Generating physically unclonable functions using PUF arrays composed of MTJs primarily involves controlling the random flipping probability of the free layer in each MTJ to be approximately 50%. However, due to the small standard deviation (Sigma) of the free layer flipping field, it is difficult to control the random flipping probability of the free layer in each magnetic tunnel junction to be within 50%, making it inconvenient to control. Summary of the Invention

[0003] This invention provides a PUF generation device based on MRAM and a PUF generation method based thereon, so as to more conveniently control the random write probability of each PUF data unit.

[0004] In a first aspect, the present invention provides a PUF generation device based on MRAM (Magnetoresistive Random Access Memory), which includes a PUF data array and a PUF data read circuit. The PUF data array consists of multiple PUF data cells, each PUF data cell including a magnetic tunnel junction composed of a free layer, a tunnel layer, a reference layer, and a pinning layer. When initializing the PUF data array using a first initialization magnetic field, the magnetic moment direction of the pinning layer in each PUF data cell is magnetized to a first direction; and when initializing the PUF data array using a second initialization magnetic field, the magnetic moment direction of the pinning layer in each PUF data cell is randomly flipped from the first direction to a second direction opposite to the first direction. The PUF data read circuit is used to read the state of each PUF data cell in the PUF data array after initializing the PUF data array using the second initialization magnetic field, thereby forming PUF data.

[0005] In the above scheme, a PUF generation device based on MRAM is constructed by using a PUF data array and a PUF data read circuit. First, the PUF data array is initialized using a first initialization magnetic field, magnetizing the magnetic moment direction of the pinned layer in each PUF data unit to the first direction. Then, a second initialization magnetic field is used to initialize the PUF data array, randomly flipping the magnetic moment direction of the pinned layer in each PUF data unit from the first direction to the second direction. Thus, the magnetic moment direction of the pinned layer in each PUF data unit is randomly located in either the first or second direction, and the number and address of PUF data units with their pinned layer magnetic moment directions in either direction exhibit significant randomness. In other words, by utilizing the randomness and unpredictability of the fabrication process during pinned layer fabrication, the flipping magnetic field that achieves the flipping of the magnetic moment direction of the pinned layer in different PUF data units has a completely random and unreplicable distribution in terms of magnetic field strength, causing the magnetic moment direction of the pinned layer in each PUF data unit to be randomly flipped from the first direction to the second direction. Because different PUF data arrays have different characteristics, they are not portable; however, the same PUF data array has good reproducibility and high reliability. The PUF data read circuit then uses the difference in the magnetic moment direction of the pinned layer (either in the first or second direction) to read the state of different PUF data cells, forming PUF data. Compared to existing technologies that control the random flipping of the free layer, this application controls the random flipping of the pinned layer. The pinned layer's flipping magnetic field distribution has a more significant and larger adjustment window than the free layer's, meaning the standard deviation of the pinned layer's flipping magnetic field is larger. This allows for easier control of the random write probability of the pinned layer in each PUF data cell flipping from the first direction to the second direction, making it closer to, but not limited to, a target random probability of 50%, thus providing an advantage in controlling the flipping probability. Furthermore, it eliminates the need for a write circuit to write data to the PUF data array, simplifying the circuit structure.

[0006] In one specific implementation, when initializing the PUF data array using a first initialization magnetic field, the magnetic tunnel junction in each PUF data cell is in a first state. When initializing the PUF data array using a second initialization magnetic field, the magnetic moment direction of the free layer of the magnetic tunnel junction in each PUF data cell is flipped; for each PUF data cell whose magnetic moment direction of the pinned layer is flipped from the first direction to the second direction, the magnetic moment direction of the reference layer in that PUF data cell is also flipped, so that the magnetic tunnel junction of that PUF data cell remains in the first state; for each PUF data cell whose magnetic moment direction of the pinned layer is not flipped from the first direction to the second direction, the magnetic tunnel junction in that PUF data cell changes from the first state to the second state. By utilizing the second initialization magnetic field, not only can the free layers in each PUF data cell be flipped, but also the antiferromagnetic coupling effect between the pinned layer and the reference layer can be used to flip the corresponding reference layer while the magnetic moment direction of the pinned layer is randomly flipped. This makes the magnetic tunnel junction state of the PUF data cell with the flipped magnetic moment direction different from that of the PUF data cell without the flipped magnetic moment direction. This allows the PUF data read circuit to read the state of each PUF data cell by utilizing the different state characteristics of the magnetic tunnel junction.

[0007] In one specific implementation, the PUF data read circuit is used to read whether the magnetic tunnel junction in each PUF data cell is in a first state or a second state. The PUF data read circuit is also used to form PUF data based on the state of the magnetic tunnel junction in each PUF data cell. By reading the state of the magnetic tunnel junction in each PUF data cell, reflecting the different states of whether the magnetic moment direction of the pinned layer in each PUF data cell has been reversed, the PUF data read circuit can accurately and reliably read the state of different PUF data cells.

[0008] In one specific implementation, the first state is one where the magnetic moment direction between the free layer and the reference layer in the magnetic tunnel junction is either parallel or antiparallel; the second state is another where the magnetic moment direction between the free layer and the reference layer in the magnetic tunnel junction is either parallel or antiparallel. This facilitates the PUF data read circuit to accurately and reliably read the state of different PUF data units.

[0009] In one specific implementation, when initializing the PUF data array using the second initialization magnetic field, the probability of writing the pinning layer of each PUF data cell to be flipped from the first direction to the second direction is 40% to 60%. By utilizing the natural randomness and unpredictable fluctuations in manufacturing, the randomness of the generated PUF data is made greater.

[0010] In one specific embodiment, the MRAM-based PUF generation device further includes: an ECC (Error Correcting Code) checksum generation module, a PUF ECC array, and a PUF ECC read / write circuit. The ECC checksum generation module generates ECC checksums based on the PUF data generated by the PUF data read circuit. The PUF ECC array consists of multiple PUF ECC units, each including a magnetic tunnel junction composed of a free layer, a tunnel layer, a reference layer, and a pinning layer. The pinning layer is used to pin the magnetic moment direction of the reference layer. The PUF ECC read / write circuit writes ECC checksums to the PUF ECC array or reads ECC checksums stored in the PUF ECC array. This increases the PUF ECC area, improves the reliability of the security chip, ensures data reproducibility, and makes PUF data output more reliable.

[0011] In one specific implementation, the MRAM-based PUF generation device further includes a write failure control circuit. The write failure control circuit is used to control the write function of the PUF ECC read-write circuit to fail after the PUF ECC read-write circuit writes the ECC check code into the PUF ECC array, so that the PUF data read-write circuit only writes the ECC check code into the PUF ECC array once, thereby improving the consistency of subsequent verification benchmarks and improving the verification effect.

[0012] In one specific implementation, the write failure control circuit is an Efuse circuit associated with the write current output by the PUF ECC read / write circuit, which facilitates the control of the write function failure of the PUF ECC read / write circuit.

[0013] In one specific implementation, the MRAM-based PUF generation device further includes a PUF ECC verification module. This module verifies the state of each PUF data unit in the PUF data array during each subsequent read of the PUF data array by the PUF data read circuit (excluding the first read), resulting in consistent PUF data. This ensures data reproducibility and makes PUF data output more reliable.

[0014] In one specific implementation, the flip magnetic field strength of the pinning layer in each PUF ECC unit is greater than the flip magnetic field strength of the pinning layer in all PUF data units, so as to prevent the second initialization magnetic field from interfering with the state of the PUF ECC array when initializing the PUF data array, thereby not affecting the subsequent normal writing of ECC check codes.

[0015] In one specific embodiment, the MRAM-based PUF generation device further includes an MRAM array composed of multiple MRAM cells. Each MRAM cell includes a magnetic tunnel junction consisting of a free layer, a tunnel layer, a reference layer, and a pinning layer. The pinning layer is used to pin the magnetic moment direction of the reference layer. Furthermore, the flip magnetic field strength of the pinning layer in each MRAM cell is greater than the flip magnetic field strength of the pinning layers in all PUF data cells, preventing interference with the state of the MRAM array during the initialization of the PUF data array by the second initialization magnetic field, thus ensuring the normal storage function of the MRAM array is not affected.

[0016] In one specific implementation, each PUF data unit, PUF ECC unit, and MRAM unit is structured as an STT-MRAM memory cell structure. The PUF data array and PUF ECC array are fabricated based on the mature STT-MRAM process, which makes them more reliable in terms of read window, manufacturing yield, and resistance to external environmental interference.

[0017] Secondly, the present invention also provides a PUF generation method, which is based on any of the above-mentioned MRAM-based PUF generation devices. The PUF generation includes: initializing a PUF data array using a first initialization magnetic field, so that the magnetic moment direction of the pinned layer in each PUF data unit is magnetized to a first direction; initializing the PUF data array using a second initialization magnetic field, so that the magnetic moment direction of the pinned layer in each PUF data unit is randomly flipped from the first direction to a second direction opposite to the first direction; and a PUF data read circuit reading the state of each PUF data unit in the PUF data array to form PUF data.

[0018] In the above scheme, a PUF generation device based on MRAM is constructed by using a PUF data array and a PUF data read circuit. First, the PUF data array is initialized using a first initialization magnetic field, magnetizing the magnetic moment direction of the pinned layer in each PUF data unit to the first direction. Then, a second initialization magnetic field is used to initialize the PUF data array, randomly flipping the magnetic moment direction of the pinned layer in each PUF data unit from the first direction to the second direction. Thus, the magnetic moment direction of the pinned layer in each PUF data unit is randomly located in either the first or second direction, and the number and address of PUF data units with their pinned layer magnetic moment directions in either direction exhibit significant randomness. In other words, by utilizing the randomness and unpredictability of the fabrication process during pinned layer fabrication, the flipping magnetic field that achieves the flipping of the magnetic moment direction of the pinned layer in different PUF data units has a completely random and unreplicable distribution in terms of magnetic field strength, causing the magnetic moment direction of the pinned layer in each PUF data unit to be randomly flipped from the first direction to the second direction. Because different PUF data arrays have different characteristics, they are not portable; however, the same PUF data array has good reproducibility and high reliability. The PUF data read circuit then uses the difference in the magnetic moment direction of the pinned layer (either in the first or second direction) to read the state of different PUF data cells, forming PUF data. Compared to existing technologies that control the random flipping of the free layer, this application controls the random flipping of the pinned layer. The pinned layer's flipping magnetic field distribution has a more significant and larger adjustment window than the free layer's, meaning the standard deviation of the pinned layer's flipping magnetic field is larger. This allows for easier control of the random write probability of the pinned layer in each PUF data cell flipping from the first direction to the second direction, making it closer to, but not limited to, a target random probability of 50%, thus providing an advantage in controlling the flipping probability. Furthermore, it eliminates the need for a write circuit to write data to the PUF data array, simplifying the circuit structure.

[0019] In one specific implementation, the PUF generation method further includes: setting a set of magnetic fields {H} with gradually increasing magnetic field strength. a H b , ...}, respectively serving as the test magnetic fields for the second initialization magnetic field; the write probability of each test magnetic field is measured to obtain the magnetic field {H}. a H b The writing probabilities corresponding to ,…} are respectively {P(H a ),P(H b ),…};According to the writing probability {P(H a ),P(H bThe expected value of the magnetic field strength of the second initialization magnetic field is calculated. Based on the expected magnetic field strength, the Trim setting is set for input to the PUF data array to initialize the PUF data array using the second initialization magnetic field with the expected magnetic field strength. This is done to account for the influence of inconsistent magnetic field strength between wafers when forming PUF data due to overall manufacturing process drift, thus more accurately determining the magnetic field strength of the second initialization magnetic field and improving PUF data quality. Attached Figure Description

[0020] Figure 1 A schematic diagram of the structure of a PUF generation device based on MRAM provided in an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram illustrating a random reversal of the magnetic moment direction of the pinning layer in each PUF data unit from a first direction to a second direction, as provided in an embodiment of the present invention.

[0022] Figure 3 A flowchart of a PUF generation method provided in an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram illustrating the state of a PUF data array between initialization by a second magnetic field, as provided in an embodiment of the present invention.

[0024] Figure 5 A typical MTJ array RH curve of scanning magnetic field from negative to positive is provided for an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the applied magnetic field strength and writing probability density provided in an embodiment of the present invention;

[0026] Figure 7 A schematic diagram of another MRAM-based PUF generation device provided in an embodiment of the present invention;

[0027] Figure 8 A flowchart of another PUF generation method provided in an embodiment of the present invention.

[0028] Figure label:

[0029] 11-Free layer 12-Tunnel layer 13-Reference layer 14-Pinning layer Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] To facilitate understanding of the MRAM-based PUF generation device provided in this embodiment of the invention, the application scenario of the MRAM-based PUF generation device is first described below. This MRAM-based PUF generation device is used to generate PUF data. The MRAM-based PUF generation device will now be described in detail with reference to the accompanying drawings.

[0032] refer to Figure 1 and Figure 2 The MRAM-based PUF generation device provided in this embodiment of the invention includes a PUF data array and a PUF data read circuit. The PUF data array consists of multiple PUF data units, each PUF data unit ( Figure 1 Each cell in the diagram represents a PUF data unit, including magnetic tunnel junctions ( Figure 1 In this context, MTJ represents a magnetic tunnel junction, which consists of a free layer 11 ( Figure 2 In this context, FL represents the free layer 11, tunnel layer 12, and reference layer 13. Figure 2 In this context, RL represents reference layer 13 and pinning layer 14. Figure 2 In this context, PL represents the pinning layer 14. When initializing the PUF data array using the first initialization magnetic field, the magnetic moment direction of the pinning layer 14 in each PUF data unit is magnetized to the first direction; and when initializing the PUF data array using the second initialization magnetic field, the magnetic moment direction of the pinning layer 14 in each PUF data unit is randomly flipped from the first direction to a second direction opposite to the first direction. The PUF data read circuit is used to read the state of each PUF data unit in the PUF data array after initializing the PUF data array using the second initialization magnetic field, forming PUF data.

[0033] In the above scheme, a PUF generation device based on MRAM is constructed by using a PUF data array and a PUF data read circuit. First, the PUF data array is initialized using a first initialization magnetic field, magnetizing the magnetic moment direction of the pinning layer 14 in each PUF data unit to the first direction. Then, a second initialization magnetic field is used to initialize the PUF data array, randomly flipping the magnetic moment direction of the pinning layer 14 in each PUF data unit from the first direction to the second direction. Thus, the magnetic moment direction of the pinning layer 14 in the PUF data unit is randomly located in either the first or second direction, and the number and address of PUF data units with the magnetic moment direction of the pinning layer 14 in either the first or second direction exhibit significant randomness. That is, by utilizing the randomness and unpredictability of the fabrication process when preparing the pinning layer 14, the distribution of the flipping magnetic field that achieves the flipping of the magnetic moment direction of the pinning layer 14 in different PUF data units, in terms of magnetic field strength and other characteristics, is completely random and non-replicable, causing the magnetic moment direction of the pinning layer 14 in each PUF data unit to be randomly flipped from the first direction to the second direction. Because different PUF data arrays have different characteristics, they are not portable; however, the same PUF data array has good reproducibility and high reliability. The PUF data read circuit then uses the difference in the magnetic moment direction of the pinning layer 14 (either in the first or second direction) to read the state of different PUF data units, forming PUF data. Compared to existing technologies that control the random flipping of the free layer 11, this application controls the random flipping of the pinning layer 14. The pinning layer 14's flipping magnetic field distribution has a more significant and larger adjustment window than the free layer 11's flipping magnetic field distribution; that is, the standard deviation of the pinning layer 14's flipping magnetic field is larger than that of the free layer 11. This makes it easier to control the random write probability of the pinning layer 14 randomly flipping from the first direction to the second direction in each PUF data unit, making it closer to, but not limited to, a target random probability of 50%, thus providing an advantage in controlling the flipping probability. Furthermore, it eliminates the need for a write circuit to write data to the PUF data array, simplifying the circuit structure. The above structure will be described in detail below with reference to the accompanying drawings.

[0034] When setting up a PUF data array, refer to Figure 1 The PUF data array consists of multiple PUF data units, each including a magnetic tunnel junction. The magnetic tunnel junction comprises a free layer 11, a tunnel layer 12, a reference layer 13, and a pinning layer 14, where the pinning layer 14 is used to pin the magnetic moment direction of the reference layer 13. Specifically, the magnetic tunnel junction may include a pinning layer 14, a reference layer 13 stacked on the pinning layer 14, a tunnel layer 12 stacked on the reference layer 13, and a free layer 11 stacked on the tunnel layer 12. Figure 1As shown, each PUF data unit also includes a MOSFET, and the connection method between the MOSFET and the magnetic tunnel junction can be referred to... Figure 1 The connection method. The number of PUF data units contained in the PUF data array can be as large as possible, in order to improve PUF security and complexity by increasing the number of PUF data units in the PUF data array.

[0035] refer to Figure 2 and Figure 3 In the production and testing process of MRAM-based PUF generation devices, random toggle states that can be read and obtained from PUF data can be generated in the PUF data array by performing two sequential magnetic field initializations. In other words, by using an externally applied toggle magnetic field, random toggle states representing PUF data are formed in the PUF data array during production or testing, eliminating the need for a separate write circuit to write PUF data to the PUF data array, thus simplifying the circuit structure.

[0036] During the initial magnetic field initialization of the PUF data array, reference Figure 2 and Figure 3 The PUF data array is initialized using a first initialization magnetic field, so that the magnetic moment direction of the pinned layer 14 in each PUF data unit is magnetized to the first direction. For example, as... Figure 2 The example shown illustrates an initialization method where the first initialization magnetic field can be a positive initialization magnetic field H. W1 This magnetizes the magnetic moment direction of the pinning layer 14 in all PUF data cells of the PUF data array to the upward direction, which is the first direction. At the same time, due to the antiferromagnetic coupling effect between the pinning layer 14 and the reference layer 13, the magnetic moment direction of the reference layer 13 in each PUF data cell is magnetized to the downward direction, which is exactly opposite to the magnetic moment direction of the pinning layer 14.

[0037] At this point, the magnetic moment directions between the free layer 11 and the reference layer 13 of the magnetic tunnel junction in each PUF data unit can be further magnetized to a first state, facilitating the subsequent PUF data read circuit to identify the flip state of the pinned layer 14 using the state of the magnetic tunnel junction. This first state can be such that the magnetic moment direction between the free layer 11 and the reference layer 13 is as follows: Figure 2 The antiparallel state (AP state) shown can be specifically as follows: Figure 2The illustrated antiparallel state is one where the magnetic moment direction of the free layer 11 is upward, away from the reference layer 13, and the magnetic moment direction of the reference layer 13 is downward, away from the free layer 11. Alternatively, it could be an antiparallel state where the magnetic moment direction of the free layer 11 is downward, towards the reference layer 13, and the magnetic moment direction of the reference layer 13 is downward, towards the free layer 11. Furthermore, this first state can also be a parallel state (P-state) where the magnetic moments of the free layer 11 and the reference layer 13 are parallel. Specifically, the magnetic moments of both the free layer 11 and the reference layer 13 can be simultaneously downward to form a parallel state, or they can be simultaneously upward to form a parallel state.

[0038] Next, the PUF data array undergoes a second magnetic field initialization, referring to... Figure 2 and Figure 3 When initializing the PUF data array using the second initialization magnetic field, the magnetic moment direction of the pinning layer 14 in each PUF data cell is randomly flipped from the first direction to a second direction opposite to the first direction. For example, as Figure 2 The example shown illustrates an initialization method where the second initialization magnetic field can be a negative initialization magnetic field H. W2 This causes the magnetic moment direction of the pinned layer 14 in each PUF data cell of the PUF data array to be randomly flipped from the upward direction to the downward direction. For example... Figure 2 The left diagram shows the pinning layer 14 without its magnetic moment direction being reversed, while the right diagram shows it with the magnetic moment direction reversed. It can be seen that the magnetic moment direction states of the pinning layer 14 in the two PUF data units are not the same. Whether the magnetic moment direction of the pinning layer 14 in each PUF data unit is reversed is random. The magnetic moment direction of the pinning layer 14 in a PUF data unit is randomly located in either the first or second direction. The number and address of PUF data units with the magnetic moment direction of the pinning layer 14 in either the first or second direction are also highly random. Utilizing the randomness and unpredictability of the fabrication process of the pinning layer 14, the reversing magnetic field that reverses the magnetic moment direction of the pinning layer 14 in different PUF data units has a completely random and non-replicable distribution in terms of magnetic field strength, causing the magnetic moment direction of the pinning layer 14 in each PUF data unit to be randomly reversed from the first direction to the second direction. Because different PUF data arrays have different characteristics, they are not portable; however, the same PUF data array has good reproducibility and high reliability. The subsequent PUF data reading circuit can read the magnetic moment direction state of the pinning layer 14 in each PUF data unit. The magnetic moment direction state of the pinning layer 14 can represent the state of the PUF data unit. Thus, the state of different PUF data units can be read by utilizing the difference between the magnetic moment direction of the pinning layer 14 being in the first direction or the second direction. Based on the magnetic moment direction states of all the pinning layers 14 in the PUF data array, PUF data is formed.

[0039] When initializing the PUF data array using the second initialization magnetic field, continue to refer to Figure 2 Furthermore, the magnetic moment direction of the free layer 11 in each PUF data cell can be reversed. This means it's possible to change the magnetic tunnel junction from a first state to a second state, where the second state is exactly the opposite of the first state. For example, if the first state is parallel, the second state can be antiparallel; if the first state is antiparallel, the second state is parallel. Of course, it's also possible that the magnetic moment directions of both the free layer 11 and the reference layer 13 of the magnetic tunnel junction are reversed, thus keeping the state of the magnetic tunnel junction unchanged.

[0040] For example, refer to Figure 2 For each PUF data cell whose magnetic moment direction of the pinning layer 14 is flipped from the first direction to the second direction, such as Figure 2 The diagram on the lower right shows that because the magnetic moment direction of the pinned layer 14 flips from upward to downward, the magnetic moment direction of the reference layer 13 in this PUF data cell is also flipped from downward to upward due to the antiferromagnetic coupling effect between the pinned layer 14 and the reference layer 13. However, because the free layer 11 of the magnetic tunnel junction also flips from upward to downward, the state of the magnetic tunnel junction in the PUF data cell after initialization by the second initialization magnetic field remains the first state, that is, it still remains in an antiparallel state, only from... Figure 2 The opposing antiparallel state at the middle height position changes to the opposing antiparallel state.

[0041] For each PUF data cell whose magnetic moment direction of pinning layer 14 has not been flipped from the first direction to the second direction, such as Figure 2The diagram on the lower left shows that because the magnetic moment direction of the pinned layer 14 has not reversed, the magnetic moment direction of the reference layer 13 also remains unchanged. However, because the free layer 11 has flipped, the magnetic tunnel junction in this PUF data cell changes from a first state of antiparallel orientation to a second state of parallel orientation. It can be seen that whether the magnetic moment direction of the pinned layer 14 has flipped can be reflected by the magnetic moment direction between the free layer 11 and the reference layer 13 in the magnetic tunnel junction. If the magnetic moment direction of the pinned layer 14 has flipped, the state of the magnetic tunnel junction in the same PUF data cell remains unchanged; if the magnetic moment direction of the pinned layer 14 has not flipped, the state of the magnetic tunnel junction in the same PUF data cell has changed. The method of setting up a read circuit to read whether the magnetic tunnel junction is in a parallel or antiparallel state is a relatively mature technology. Therefore, when setting up a PUF data read circuit, the design method of reading whether the magnetic tunnel junction is in a parallel or antiparallel state can be used as a reference to indirectly obtain information about whether the pinned layer 14 in each PUF data cell has reversed. That is, when reading the state of each PUF data cell, it is not necessary to focus on whether the magnetic field direction of the pinned layer 14 in each PUF data cell has been reversed, but only on the state of the magnetic tunnel junction in each PUF data cell. The randomness of the state of the magnetic tunnel junction is used to form PUF data. In other words, by using the second initialization magnetic field, not only can the free layer 11 in each PUF data cell be reversed, but also, while the magnetic moment direction of the pinned layer 14 is randomly reversed, the antiferromagnetic coupling effect between the pinned layer 14 and the reference layer 13 can be used to reverse the corresponding reference layer 13. This makes the state of the magnetic tunnel junction of the PUF data cell with the reversed magnetic moment direction of the pinned layer 14 different from that of the PUF data cell without the reversed magnetic moment direction. This allows the PUF data reading circuit to accurately and reliably read the state of different PUF data cells by utilizing the different states of the magnetic tunnel junction.

[0042] When initializing the PUF data array using the second initialization magnetic field, the magnetic field strength can be adjusted so that the probability of writing each PUF data cell's pinning layer 14 being flipped from the first direction to the second direction is any value between 40% and 60%, such as 40%, 45%, 50%, 55%, or 60%, making the write probability close to or equal to 50%. Therefore, when the number of PUF data cells in the PUF data array is sufficiently large, the flipping probability of the magnetic moment direction of the pinning layer 14 in each PUF data cell being flipped is approximately equal to the proportion of all PUF data cells in the PUF data array whose magnetic moment direction of the pinning layer 14 is flipped to the entire PUF data array. By utilizing the inherent randomness and unpredictable fluctuations in manufacturing, the randomness of the PUF data is increased, resulting in greater randomness in the generated PUF data. Figure 4The diagram illustrates the state changes of each magnetic tunnel junction after initializing a PUF data array with a second initialization magnetic field. This PUF data array contains nine PUF data cells. After initializing the PUF data array with a first initialization magnetic field, the state of each PUF data cell is as follows: Figure 2 The state at the middle height position is in an antiparallel state. After initializing the PUF data array with the second initialization magnetic field, the state of the magnetic tunnel junction in 5 out of the 9 PUF data cells changes from antiparallel to parallel, while the state of the magnetic tunnel junction in 4 of the PUF data cells remains antiparallel, thus making the write probability close to 50%. During this process, according to the flipping principle shown above, the magnetization direction of the pinned layer 14 in the 4 PUF data cells where the magnetic tunnel junction state remains antiparallel is flipped (from the first direction to the second direction), while the magnetization direction of the pinned layer 14 in the 5 PUF data cells where the magnetic tunnel junction state changes does not flip. Therefore, we can focus only on the state change of the magnetic tunnel junction and use the address and number of magnetic tunnel junction state changes to form PUF data.

[0043] When determining the magnetic field strength of the second initial magnetic field, Figure 5 A typical PUF data array RH curve is shown, with the resistance changes representing the flipping of free layer 11, pinned layer 14, and reference layer 13, respectively. (Reference layer 13 is also shown.) Figure 5 As the applied magnetic field strength gradually increases from 0 in the positive direction, initially the magnetic moment direction of the free layer 11 in each magnetic tunnel junction reverses. Then, the magnetic moment direction of the pinned layer 14 flips, and simultaneously, utilizing the antiferromagnetic coupling effect between the pinned layer 14 and the reference layer 13, the reference layer 13 also flips. When the magnetic field strength increases sufficiently, the antiferromagnetic coupling effect between the pinned layer 14 and the reference layer 13 disappears, causing the reference layer 13 to flip again, resulting in the magnetic moment directions of the free layer 11, pinned layer 14, and reference layer 13 all being the same. Figure 5 It can be seen that the range of the flipping magnetic field strength when the free layer 11 flips is smaller than the range of the flipping magnetic field strength when the pinned layer 14 flips. Figure 6 This is a schematic diagram illustrating the relationship between the applied magnetic field strength and the write probability density. (Through...) Figure 6It can be seen that the mean magnetic field strength of the flipped magnetic field of the free layer 11 is less than that of the flipped magnetic field of the pinned layer 14; the standard deviation of the magnetic field strength of the flipped magnetic field of the free layer 11 is less than that of the flipped magnetic field of the pinned layer 14. For details, please refer to Table 1 below, which shows the mean and standard deviation of the magnetic field strengths of the flipped magnetic fields of the free layer 11, pinned layer 14, and reference layer 13. It is clearly evident below that the standard deviation of the magnetic field strength of the flipped magnetic field of the free layer 11 is 113.16, which is much smaller than the standard deviation of the magnetic field strength of the flipped magnetic field of the pinned layer 14 (556.52).

[0044] Table 1 - Mean and standard deviation of magnetic field strength for the flipping magnetic fields of free layer 11, pinned layer 14 and reference layer 13

[0045]

[0046] pass Figure 5 , Figure 6 As shown in Table 1, compared to flipping using the free layer 11, the magnetic field strength of the flipping magnetic field of the pinned layer 14 has a significantly larger sigma, making it more controllable and providing a larger window close to 50%. Therefore, it is feasible to achieve a PUF data write probability of around 50% using the pinned layer 14 flipping method, and it has advantages over using the free layer 11 flipping method. Specifically, compared to existing technologies that control the random flipping of the free layer 11, this application controls the random flipping of the pinned layer 14. The flipping magnetic field distribution of the pinned layer 14 has a more significant and larger adjustment window than the flipping magnetic field distribution of the free layer 11; that is, the standard deviation of the flipping magnetic field of the pinned layer 14 is larger than that of the free layer 11. This makes it easier to control the random write probability of the pinned layer 14 randomly flipping from the first direction to the second direction in each PUF data cell, making it closer to a target random probability such as, but not limited to, 50%, thus providing a greater advantage in controlling the flipping probability.

[0047] The following illustrates a specific procedure for determining the magnetic field strength of the second initial magnetic field. (Reference) Figure 6 Set a set of magnetic fields {H} with gradually increasing magnetic field strength. a H b , ...}, are respectively used as the test magnetic fields for the second initialization magnetic field. Then, the write probability of each test magnetic field is measured to obtain the magnetic field {H}. a H b The writing probabilities corresponding to ,…} are respectively {P(H a ),P(H b Then, based on the writing probability {P(H)}, ...} a ),P(H bThe expected value of the magnetic field strength of the second initialization magnetic field is calculated. Next, based on the expected magnetic field strength, the Trim setting input to the PUF data array is set to initialize the PUF data array using the second initialization magnetic field with the expected magnetic field strength. This takes into account the potential inconsistency in the magnetic field strength of the second initialization magnetic field when forming PUF data between wafers due to overall manufacturing process drift, thus more accurately determining the magnetic field strength of the second initialization magnetic field and improving PUF data quality.

[0048] After initializing the PUF data array using the second initialization magnetic field, the PUF data read circuit reads the state of each PUF data cell in the PUF data array to form PUF data. Specifically, the PUF data read circuit can read the magnetic moment direction of the pinning layer 14 in each PUF data cell to determine the state of each PUF data cell and form PUF data based on the state of the PUF data cell. Alternatively, as previously shown, given that the magnetic moment direction of the pinning layer 14 is different, the state of the magnetic tunnel junction in the same PUF data cell will also be different. The circuit can then read the state of the magnetic tunnel junction in each PUF data cell to form PUF data based on the state of the magnetic tunnel junction. Specifically, the PUF data read circuit reads whether the magnetic tunnel junction in each PUF data cell is in a first state or a second state, and then forms PUF data based on the state of the magnetic tunnel junction in each PUF data cell. By reading the state of the magnetic tunnel junction in each PUF data cell, which reflects the different states of whether the magnetic moment direction of the pinned layer 14 in each PUF data cell has been reversed, the PUF data read circuit can accurately and reliably read the state of different PUF data cells. For example... Figure 1 As shown, the PUF data read circuit may include word lines (WL), bit lines (BL), power lines (SL), and a read voltage (V) input to the PUF data array. R The power supply for reading () can be referenced for its connection method. Figure 1 The connection method.

[0049] Additionally, a structure can be added to execute the PUF ECC function for error correction, improving the accuracy of PUF data read during subsequent use and mitigating potential misreading issues during data verification. For details, please refer to [link / reference]. Figure 7 and Figure 8 The MRAM-based PUF generation device may further include: an ECC checksum generation module, a PUF ECC array, and a PUF ECC read / write circuit. The ECC checksum generation module generates ECC checksums based on the PUF data generated by the PUF data read circuit, and each ECC checksum corresponds one-to-one with the corresponding PUF data. Figure 7The PUF ECC array shown consists of multiple PUF ECC units. Each PUF ECC unit includes a magnetic tunnel junction and a pinning layer 14 that pins the magnetic moment direction of the reference layer 13 in the magnetic tunnel junction. It may also include a MOS transistor. For its specific structure, please refer to [reference needed]. Figure 1 The setup and connection method are shown. The PUF ECC read / write circuit is used to write ECC checksums to the PUF ECC array or read ECC checksums stored in the PUF ECC array. (Reference) Figure 7 The PUF ECC read / write circuit can utilize the write voltage V W1 To write ECC checksums into the PUF ECC array. The write voltage V W1 It can be large enough to ensure that the ECC checksum is accurately written into the PUF ECC array.

[0050] By designing the PUF ECC function, the small resistance difference between the magnetic tunnel junction in the PUF data cell and its first and second states is considered. Furthermore, during subsequent use, factors such as temperature and power supply fluctuations may cause the PUF data read circuit to retrieve data from the PUF data array during data verification operations to differ from the initial PUF data, potentially leading to misleading information. In short, by adding a PUF ECC region, the reliability of the security chip is improved, data reproducibility is guaranteed, and PUF data output becomes more reliable.

[0051] Furthermore, during the initialization of the PUF data array using the first initialization magnetic field, the magnetic moments of the pinned layer 14, reference layer 13, and free layer 11 in each PUF ECC cell of the PUF ECC array can also be initialized simultaneously, thereby setting the magnetic moment direction of the pinned layer 14. This allows the flip magnetic field strength of the pinned layer 14 in each PUF ECC cell to be greater than the flip magnetic field strength of the pinned layer 14 in all PUF data cells. Specific implementation methods include, but are not limited to, using photoresist to cover the PUF data array area and the PUF ECC array area separately, and employing separate magnetic tunnel junction etching processes for each. This prevents interference with the state of the PUF ECC array during the initialization of the PUF data array using the second initialization magnetic field, ensuring that subsequent normal writing of ECC checksums is not affected.

[0052] In practical applications, a write failure control circuit can be further integrated into the MRAM-based PUF generation device. This circuit disables the write function of the PUF ECC read / write circuit after the ECC checksum is written to the PUF ECC array, ensuring that the PUF data read / write circuit only writes the ECC checksum once to the PUF ECC array. This improves the consistency of subsequent verification bases and enhances verification effectiveness. When configuring the write failure control circuit, an efuse circuit can be used as part of it, and the efuse circuit's write current output is correlated with the PUF ECC read / write circuit's write current, facilitating the control of the PUF ECC read / write circuit's write function. It should be understood that the configuration of the failure control circuit is not limited to the design using an efuse circuit shown above; other configuration methods can also be employed.

[0053] Furthermore, in the specific implementation of PUF ECC verification, the MRAM-based PUF generation device can further include a PUF ECC verification module, as shown in the reference. Figure 8 The PUF ECC verification module is used to verify the state of each PUF data unit in the PUF data array during each subsequent read of the PUF data array by the PUF data read circuit, except for the first read. This ensures that the final output PUF data after each subsequent read of the PUF data array by the PUF data read circuit is consistent, guaranteeing data reproducibility and making the PUF data output more reliable. The specific verification process can be as follows: After the PUF data read circuit reads the PUF data array again to form PUF data, the PUF ECC checksum generation module can generate an ECC checksum again. This ECC checksum is compared with the initial ECC checksum stored in the PUF ECC array. Using the ECC error correction function, the PUF data formed by the reread is detected and verified to be consistent with the PUF data formed by the initial read. Therefore, even if there are unstable PUF data units in the PUF data array, the output PUF data can still be consistent, achieving PUF data reproducibility.

[0054] Furthermore, the MRAM-based PUF generation device may further include an MRAM array composed of multiple MRAM cells. Each MRAM cell includes a magnetic tunnel junction, which consists of a free layer 11, a tunnel layer 12, a reference layer 13, and a pinning layer 14, wherein the pinning layer 14 is used to pin the magnetic moment direction of the reference layer 13. Each MRAM cell may also include a MOSFET, the connection method of which can be referred to... Figure 1The connection method is shown. Of course, an MRAM read / write circuit can also be set in the MRAM array to write data to or read data from the MRAM array. When initializing the PUF data array using the first initialization magnetic field, the magnetic moments of the pinning layer 14, reference layer 13, and free layer 11 in each MRAM cell of the MRAM array can also be initialized simultaneously, thereby setting the magnetic moment direction of the pinning layer 14. Furthermore, the flip magnetic field strength of the pinning layer 14 in each MRAM cell can be made greater than the flip magnetic field strength of the pinning layer 14 in all PUF data cells. Specific implementation methods include, but are not limited to: using photoresist to cover the PUF data array area, PUFECC array area, and MRAM array area respectively, and using separate magnetic tunnel junction etching processes for each. This prevents the second initialization magnetic field from interfering with the state of the MRAM array during the initialization of the PUF data array, thus not affecting the normal storage function of the MRAM array.

[0055] Furthermore, the structure of each PUF data unit, PUF ECC unit, and MRAM unit can be an STT-MRAM memory cell structure, using the mature STT-MRAM process to fabricate the PUF data array and PUF ECC array, thus improving reliability in terms of read window, manufacturing yield, and resistance to external environmental interference. It should be noted that the structure of each PUF data unit, PUF ECC unit, and MRAM unit can also be other structures including a magnetic tunnel junction and reference layer 13. For example, SOT-MRAM fabrication can be used, making each PUF data unit, PUF ECC unit, and MRAM unit a cell structure fabricated based on SOT-MRAM.

[0056] A PUF generation device based on MRAM is constructed by employing a PUF data array and a PUF data read circuit. First, the PUF data array is initialized using a first initialization magnetic field, magnetizing the magnetic moment direction of the pinning layer 14 in each PUF data unit to the first direction. Then, a second initialization magnetic field is used to initialize the PUF data array, randomly flipping the magnetic moment direction of the pinning layer 14 in each PUF data unit from the first direction to the second direction. Thus, the magnetic moment direction of the pinning layer 14 in each PUF data unit is randomly located in either the first or second direction, and the number and address of PUF data units with the magnetic moment direction of the pinning layer 14 in either the first or second direction exhibit significant randomness. In other words, by utilizing the randomness and unpredictability of the fabrication process during the preparation of the pinning layer 14, the distribution of the flipping magnetic field that achieves the flipping of the magnetic moment direction of the pinning layer 14 in different PUF data units, in terms of magnetic field strength and other characteristics, is completely random and non-replicable, causing the magnetic moment direction of the pinning layer 14 in each PUF data unit to be randomly flipped from the first direction to the second direction. Because different PUF data arrays have different characteristics, they are not portable; however, the same PUF data array has good reproducibility and high reliability. The PUF data read circuit then uses the difference in the magnetic moment direction of the pinning layer 14 (either in the first or second direction) to read the state of different PUF data cells, forming PUF data. Compared to existing technologies that control the random flipping of the free layer 11, this application controls the random flipping of the pinning layer 14. The pinning layer 14's flipping magnetic field distribution has a more significant and larger adjustment window than the free layer 11's flipping magnetic field distribution; that is, the standard deviation of the pinning layer 14's flipping magnetic field is larger than that of the free layer 11. This makes it easier to control the random write probability of the pinning layer 14 randomly flipping from the first direction to the second direction in each PUF data cell, making it closer to, but not limited to, a target random probability of 50%, thus providing an advantage in controlling the flipping probability. Furthermore, it eliminates the need for a write circuit to write data to the PUF data array, simplifying the circuit structure.

[0057] In addition, embodiments of the present invention also provide a PUF generation method, see reference. Figure 1 and Figure 2 The PUF generation method is based on any of the above-mentioned MRAM-based PUF generation devices, and the PUF generation includes:

[0058] The PUF data array is initialized using the first initialization magnetic field, so that the magnetic moment direction of the pinned layer 14 in each PUF data unit is magnetized to the first direction;

[0059] The PUF data array is initialized using a second initialization magnetic field, so that the magnetic moment direction of the pinning layer 14 in each PUF data cell is randomly flipped from the first direction to a second direction opposite to the first direction;

[0060] The PUF data read circuit reads the state of each PUF data unit in the PUF data array to form PUF data.

[0061] In the above scheme, a PUF generation device based on MRAM is constructed by using a PUF data array and a PUF data read circuit. First, the PUF data array is initialized using a first initialization magnetic field, magnetizing the magnetic moment direction of the pinning layer 14 in each PUF data unit to the first direction. Then, a second initialization magnetic field is used to initialize the PUF data array, randomly flipping the magnetic moment direction of the pinning layer 14 in each PUF data unit from the first direction to the second direction. Thus, the magnetic moment direction of the pinning layer 14 in the PUF data unit is randomly located in either the first or second direction, and the number and address of PUF data units with the magnetic moment direction of the pinning layer 14 in either the first or second direction exhibit significant randomness. That is, by utilizing the randomness and unpredictability of the fabrication process when preparing the pinning layer 14, the distribution of the flipping magnetic field that achieves the flipping of the magnetic moment direction of the pinning layer 14 in different PUF data units, in terms of magnetic field strength and other characteristics, is completely random and non-replicable, causing the magnetic moment direction of the pinning layer 14 in each PUF data unit to be randomly flipped from the first direction to the second direction. Because different PUF data arrays have different characteristics, they are not portable; however, the same PUF data array has good reproducibility and high reliability. The PUF data read circuit then uses the difference in the magnetic moment direction of the pinning layer 14 (either in the first or second direction) to read the state of different PUF data units, forming PUF data. Compared to existing technologies that control the random flipping of the free layer 11, this application controls the random flipping of the pinning layer 14. The pinning layer 14's flipping magnetic field distribution has a more significant and larger adjustment window than the free layer 11's, meaning the standard deviation of the pinning layer 14's flipping magnetic field is larger than that of the free layer 11. This makes it easier to control the random write probability of the pinning layer 14 randomly flipping from the first direction to the second direction in each PUF data unit, making it closer to, but not limited to, a target random probability of 50%, thus offering an advantage in controlling the flipping probability. Furthermore, it eliminates the need for a write circuit to write data to the PUF data array, simplifying the circuit structure. The specific execution method for each step can be found in the preceding description of the structure, and will not be repeated here.

[0062] Furthermore, the PUF generation method may also include the following steps:

[0063] Set a set of magnetic fields {H} with gradually increasing magnetic field strength. a H b ,…}, respectively serving as the test magnetic fields for the second initialization magnetic field;

[0064] Measure the write probability of each magnetic field to be tested to obtain the magnetic field {H}. a H b The writing probabilities corresponding to ,…} are respectively {P(H a ),P(H b ),…};

[0065] Based on the writing probability {P(H a ),P(H b ),…}, calculate the expected value of the magnetic field strength of the second initial magnetic field;

[0066] Based on the expected magnetic field strength, the Trim setting is set for input to the PUF data array to initialize the PUF data array using the second initial magnetic field of the expected magnetic field strength.

[0067] The operation methods for each of the above steps can be referred to the corresponding descriptions of the structure above, and will not be repeated here. Through the above steps, the influence of inconsistent magnetic field strength of the second initialization magnetic field when forming PUF data between wafers due to the overall drift of the manufacturing process is taken into account, so as to more accurately determine the magnetic field strength of the second initialization magnetic field and improve the PUF data quality.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A PUF generation device based on MRAM, characterized in that, include: A PUF data array composed of multiple PUF data units; wherein each PUF data unit includes a magnetic tunnel junction composed of a free layer, a tunnel layer, a reference layer, and a pinning layer; when the PUF data array is initialized with a first initialization magnetic field, the magnetic moment direction of the pinning layer in each PUF data unit is magnetized to a first direction; and when the PUF data array is initialized with a second initialization magnetic field, the magnetic moment direction of the pinning layer in each PUF data unit is randomly flipped from the first direction to a second direction opposite to the first direction; The PUF data read circuit is used to read the state of each PUF data unit in the PUF data array after initializing the PUF data array with the second initialization magnetic field, thereby forming PUF data.

2. The PUF generation device as described in claim 1, characterized in that, When the PUF data array is initialized using the first initialization magnetic field, the magnetic tunnel junction in each PUF data cell is in the first state; When initializing the PUF data array using the second initialization magnetic field, the magnetic moment direction of the free layer of the magnetic tunnel junction in each PUF data cell is flipped; for each PUF data cell whose magnetic moment direction of the pinned layer is flipped from the first direction to the second direction, the magnetic moment direction of the reference layer in that PUF data cell is also flipped, so that the magnetic tunnel junction of that PUF data cell remains in the first state; for each PUF data cell whose magnetic moment direction of the pinned layer is not flipped from the first direction to the second direction, the magnetic tunnel junction in that PUF data cell changes from the first state to the second state.

3. The PUF generation device as described in claim 2, characterized in that, The PUF data read circuit is used to read whether the magnetic tunnel junction in each PUF data unit is in the first state or in the second state; The PUF data read circuit is also used to form the PUF data based on the state of the magnetic tunnel junction in each PUF data unit.

4. The PUF generation device as described in claim 2, characterized in that, The first state is a state in which the magnetic moment directions between the free layer and the reference layer in the magnetic tunnel junction are either parallel or antiparallel. The second state is another state in which the magnetic moment direction between the free layer and the reference layer in the magnetic tunnel junction is in the parallel state and the antiparallel state.

5. The PUF generation device as described in claim 1, characterized in that, When the PUF data array is initialized using the second initialization magnetic field, the probability of writing the pinning layer of each PUF data cell to be flipped from the first direction to the second direction is 40% to 60%.

6. The PUF generation device as described in claim 1, characterized in that, Also includes: The ECC checksum generation module is used to generate an ECC checksum based on the PUF data generated by the PUF data reading circuit. A PUF ECC array consisting of multiple PUF ECC units; wherein each PUF ECC unit includes a magnetic tunnel junction consisting of a free layer, a tunnel layer, a reference layer and a pinning layer, the pinning layer being used to pin the magnetic moment direction of the reference layer; The PUF ECC read / write circuit is used to write the ECC check code into the PUF ECC array or read the ECC check code stored in the PUF ECC array.

7. The PUF generation device as described in claim 6, characterized in that, It also includes a write failure control circuit, which is used to control the write function of the PUF ECC read-write circuit to fail after the PUF ECC read-write circuit writes the ECC check code into the PUF ECC array.

8. The PUF generation device as described in claim 7, characterized in that, The write failure control circuit is an Efuse circuit associated with the write current output by the PUFECC read / write circuit.

9. The PUF generation device as described in claim 6, characterized in that, Also includes: The PUF ECC verification module is used to verify the state of each PUF data unit in the PUF data array during each reading of the PUF data read circuit, except for the first reading, to form the PUF data.

10. The PUF generation device as described in claim 6, characterized in that, The flip magnetic field strength of the pinned layer in each PUF ECC cell is greater than the flip magnetic field strength of the pinned layer in all PUF data cells.

11. The PUF generation device as described in claim 1, characterized in that, Also includes: An MRAM array consisting of multiple MRAM cells; Each MRAM cell includes a magnetic tunnel junction consisting of a free layer, a tunnel layer, a reference layer, and a pinning layer. The pinning layer is used to pin the magnetic moment direction of the reference layer. Furthermore, the flip magnetic field strength of the pinning layer in each MRAM cell is greater than the flip magnetic field strength of the pinning layer in all PUF data cells.

12. A PUF generation method, said PUF generation method being based on the MRAM-based PUF generation device according to any one of claims 1 to 11, characterized in that, include: The PUF data array is initialized using a first initialization magnetic field, so that the magnetic moment direction of the pinned layer in each PUF data unit is magnetized to the first direction. The PUF data array is initialized using a second initialization magnetic field, so that the magnetic moment direction of the pinned layer in each PUF data unit is randomly flipped from the first direction to a second direction opposite to the first direction; The PUF data read circuit reads the state of each PUF data unit in the PUF data array to form PUF data.

13. The PUF generation method as described in claim 12, characterized in that, Also includes: Set a set of magnetic fields {H} with gradually increasing magnetic field strength. a H b ,…}, respectively serving as the magnetic fields to be measured for the second initialization magnetic field; Measure the write probability of each magnetic field to be tested to obtain the magnetic field {H}. a H b The writing probabilities corresponding to ,…} are respectively {P(H a ),P(H b ),…}; According to the writing probability {P(H a ),P(H b ),…}, calculate the expected value of the magnetic field strength of the second initial magnetic field; Based on the expected magnetic field strength value, the Trim setting is set for input to the PUF data array to initialize the PUF data array using the second initialization magnetic field of the expected magnetic field strength value.

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