Flash memory data retention capability rapid measurement method

Abstract

The present application relates to a kind of quick measurement methods of flash memory data storage capacity at room temperature, by the first ambient temperature value to the flash memory is applied preset voltage value, and the first current density value flowing through the flash memory at the first ambient temperature value is measured, the first ambient temperature value is increased to the second ambient temperature value, and the preset voltage value is applied to the flash memory at the second ambient temperature value, and the second current density value flowing through the flash memory at the second ambient temperature value is measured, and according to the first current density value and the second current density value obtained by measurement, the index value indicating the data storage capacity of flash memory is processed.The whole measurement process can be carried out at room temperature, test quickly, without high temperature cycle test, and the flash memory only needs to withstand 1.5-2.5 times of the working voltage of the flash memory during the whole test, so that the flash memory will not be damaged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of memory, in particular to a fast measurement method of data retention capability of flash memory. BACKGROUND

[0002] Flash memory is a kind of non-volatile memory, which can retain data in the flash memory after the external voltage is removed, i.e. the physical manifestation is that the charge is saved in the storage layer of the flash memory. Among them, the data retention capability is one of the important standards to characterize the performance of flash memory. Therefore, measuring the data retention capability of flash memory becomes the key to evaluate the performance of flash memory.

[0003] The existing measurement method for the data retention capability of flash memory mainly adopts cycle test, i.e. continuously performing write-erase operation on the flash memory at high temperature, and measuring the threshold voltage change of the device.

[0004] However, the existing measurement method for the data retention capability of flash memory has the following deficiencies:

[0005] Firstly, the cycle test is time-consuming. Without considering the heating time of the flash memory, only the cycle test (i.e. the cycle of write-erase operation) at high temperature usually needs to consume time for more than two weeks, for example, it is common to need to do 500 hours of cycle test at 85 degrees Celsius.

[0006] Secondly, the cycle test at high temperature will cause irreversible damage to the flash memory, which will have a great adverse effect on the flash memory. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a fast measurement method of data retention capability of flash memory for the above-mentioned prior art. The fast measurement method of data retention capability of flash memory can quickly complete the measurement of the data retention capability of flash memory at room temperature, and will not cause damage to the flash memory.

[0008] The technical solution adopted by the present application to solve the above technical problem is: a fast measurement method of data retention capability of flash memory, characterized in that it comprises the following steps:

[0009] Step 1: applying a preset voltage value to the flash memory at a first environmental temperature value, and measuring a first current density value flowing through the flash memory at the first environmental temperature value; wherein the first environmental temperature value is marked as T1, and T1 is within the temperature range of normal working of the flash memory;

[0010] Step 2: Increase the first ambient temperature value to the second ambient temperature value, apply a preset voltage value to the flash memory at the second ambient temperature value, and measure the second current density value flowing through the flash memory at the second ambient temperature value; wherein, the second ambient temperature value is marked as T2, T2>T1, and T2 is within the normal operating temperature range of the flash memory;

[0011] Step 3: Based on the measured first current density value and second current density value, process them to obtain the index value characterizing the data storage capability of the flash memory.

[0012] Improvedly, in the rapid measurement method for the data retention capacity of the flash memory, the first current density value is labeled as The second current density value is marked as First current density value and the second current density value The calculation methods are as follows:

[0013] J = J1 + J2;

[0014] Where J is the current density flowing through the flash memory at ambient temperature T, J1 is the drift current related to ambient temperature T, J2 is the leakage current of the storage layer within the flash memory, which is independent of ambient temperature T, K is the Boltzmann constant, e is the charge of a single electron, and E... i (t) represents the electric field intensity at time t, d is the distance between the plates, and a and b are constants. Φ B is the electric potential energy constant.

[0015] Furthermore, in the rapid measurement method for the data retention capacity of the flash memory, the first current density value drift current value The second current density value drift current value The unknown coefficient A is calculated as follows:

[0016]

[0017]

[0018] Further improvements include, in the rapid measurement method for the data retention capacity of the flash memory, the first current density value... The value of the loss current in The second current density value The value of the loss current in in,

[0019] Furthermore, in the rapid measurement method for the data retention capacity of the flash memory, the index value characterizing the data retention capacity of the flash memory is denoted as δ, and the index value δ is calculated as follows: Among them, the smaller the index value δ of the flash memory, the stronger the data storage capability of the flash memory.

[0020] In a further improvement, the rapid measurement method for the data retention capacity of the flash memory includes, after completing step 3, measuring the data retention capacity of the flash memory again according to steps S1 to S7 as follows:

[0021] Step S1: Prepare the experimental device circuit and the control device circuit in advance; wherein, the experimental device circuit includes an experimental flash memory and an experimental pulse generator capable of sending pulse voltage to the experimental flash memory; the control device circuit includes a control flash memory and a control pulse generator capable of sending pulse voltage to the control flash memory; the experimental flash memory is the flash memory mentioned in steps 1 to 3.

[0022] Step S2: The experimental pulse generator sends a first pulse voltage to the experimental flash memory, and the control pulse generator sends a second pulse voltage to the control flash memory; wherein the first pulse voltage and the second pulse voltage are equal in value;

[0023] Step S3: Record the first current density value of the experimental flash memory at each moment within a preset time period.

[0024] Step S4: Record the second current density value corresponding to each moment within a preset time period of the comparison flash memory; wherein the recording interval of the second current density value is equal to that of the first current density value.

[0025] Step S5: Calculate the difference in current density values ​​between the experimental flash memory and the control flash memory at each moment within a preset time period; wherein, the difference in current density values ​​is the difference between the first current density value and the second current density value at the same moment.

[0026] Step S6: Construct a straight line in a rectangular coordinate system showing the change of all the current density value differences over time; wherein, in the rectangular coordinate system, the current density value difference is the y-axis and the time corresponding to the current density value difference is the x-axis.

[0027] Step S7: Calculate the slope of the obtained straight line, and use the magnitude of the correlation value that is positively correlated with the slope to characterize the data storage capability of the flash memory; wherein, the smaller the slope value, the stronger the data storage capability of the flash memory.

[0028] Optionally, in the rapid measurement method for the data retention capacity of the flash memory, the associated value is a slope value or the tilt angle of the straight line relative to the x-axis.

[0029] Preferably, in the rapid measurement method for the data retention capacity of the flash memory, the experimental pulse generator and the control pulse generator simultaneously generate pulse voltages.

[0030] In a further improvement, in the rapid measurement method for the data retention capacity of the flash memory, both the preset voltage value and the voltage value of the first pulse voltage are 1.5 to 2.5 times the operating voltage of the flash memory.

[0031] In a further improvement, in the rapid measurement method for the data retention capacity of the flash memory, the fusion result of the data retention capacity of the flash memory measured in step S3 and the data retention capacity of the flash memory measured in step S7 is taken as the measurement result of the data retention capacity of the flash memory.

[0032] Compared with the prior art, the advantages of the present invention are as follows: in the rapid measurement method for the data storage capacity of flash memory in the present invention, the entire measurement process is fast. Furthermore, during the test, the flash memory only needs to withstand 1.5 to 2.5 times the flash memory operating voltage, so that it will not cause any damage to the flash memory. Attached Figure Description

[0033] Figure 1 This is a schematic flowchart of a method for rapidly measuring the data retention capacity of a flash memory in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of a rapid measurement method for the data retention capacity of a flash memory, which is further adopted in an embodiment of the present invention.

[0035] Figure 3 This is a schematic diagram of the experimental device circuit in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the circuit of the control device in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram showing how the difference in current density values ​​changes over time. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] This embodiment provides a method for rapidly measuring the data retention capacity of a flash memory. Specifically, see [link to documentation]. Figure 1 As shown, the method for rapidly measuring the data retention capacity of a flash memory in this embodiment includes the following steps:

[0040] Step 1: Apply a preset voltage value to the flash memory at a first ambient temperature value, and measure the first current density value flowing through the flash memory at this first ambient temperature value; wherein, the first ambient temperature value is denoted as T1, and T1 is within the normal operating temperature range of the flash memory, for example, the first ambient temperature value T1 here is an absolute temperature of 293 degrees; the first current density value is denoted as...

[0041] Step 2: Increase the first ambient temperature value to a second ambient temperature value, and apply a preset voltage value to the flash memory at the second ambient temperature value, and measure the second current density value flowing through the flash memory at the second ambient temperature value; wherein, the second ambient temperature value is denoted as T2, T2>T1, and T2 is within the normal operating temperature range of the flash memory, for example, the second ambient temperature value here is an absolute temperature of 303 degrees; the second current density value is denoted as...

[0042] Step 3: Based on the measured first and second current density values, process them to obtain an index value characterizing the data retention capability of the flash memory. Here, the index value characterizing the data retention capability of the flash memory is denoted as δ.

[0043] In this embodiment, the first current density value Second current density value The calculation methods are as follows:

[0044] J = J1 + J2;

[0045] Where J is the current density flowing through the flash memory at ambient temperature T, J1 is the drift current related to ambient temperature T, J2 is the leakage current of the storage layer within the flash memory, which is independent of ambient temperature T, K is the Boltzmann constant, e is the charge of a single electron, and E... i (t) represents the electric field intensity at time t, d is the distance between the plates, and a and b are constants. Φ B is the electric potential energy constant.

[0046] Assuming, in this embodiment, the first current density value J is... T1 drift current value Second current density value drift current value The unknown coefficient A is calculated as follows:

[0047]

[0048]

[0049] In other words, due to the first current density value Second current density value It can be measured by an ammeter, and also depends on the first ambient temperature value T1, the second ambient temperature value T2, the Boltzmann constant K, the charge of a single electron e, and the potential energy constant Φ. B The electric field intensity E at time t i Since (t), the distance between the plates d, and the constants a and b are all known or can be obtained through equipment measurement, the value of coefficient A can be calculated. Furthermore, the first current density value can be calculated. The value of the loss current in Second current density value The value of the loss current in in,

[0050] In this embodiment, the index value characterizing the data retention capability of the flash memory is set as follows: Among them, the smaller the index value δ of the flash memory, the stronger the data storage capability of the flash memory.

[0051] Of course, depending on the actual measurement needs, see [reference needed]. Figure 2 As shown, the data retention capacity of the flash memory can be measured again following steps S1 to S7:

[0052] Step S1: Prepare the experimental setup circuit and the control setup circuit in advance; wherein:

[0053] The experimental device circuit includes an experimental flash memory, a sliding resistor, an experimental pulse generator that can send pulse voltages to the experimental flash memory, an ammeter that measures the current flowing through the experimental flash memory, and a voltmeter that measures the voltage on the experimental flash memory. The experimental flash memory is the flash memory mentioned in steps 1 to 3.

[0054] The control device circuit includes a control flash memory, a sliding resistor, a control pulse generator capable of emitting a pulse voltage to the control flash memory, an ammeter for measuring the current flowing through the control flash memory, and a voltmeter for measuring the voltage on the control flash memory.

[0055] See the circuit diagram of the experimental setup. Figure 3 As shown, see the circuit diagram of the reference device. Figure 4As shown; in the experimental device circuit, since the sliding resistor can be adjusted, the resistance value of the sliding resistor can be adjusted as needed, thereby achieving the purpose of adjusting the voltage value on the experimental flash memory; similarly, in the control device circuit, since the sliding resistor can be adjusted, the resistance value of the sliding resistor can also be adjusted as needed, thereby achieving the purpose of adjusting the voltage value on the control flash memory.

[0056] Step S2: The experimental pulse generator sends a first pulse voltage to the experimental flash memory, and the control pulse generator sends a second pulse voltage to the control flash memory; wherein the first pulse voltage and the second pulse voltage are equal; and preferably, the experimental pulse generator and the control pulse generator send pulse voltages simultaneously; that is, the interval between the pulse voltages sent by the two pulse generators is the same.

[0057] In this embodiment, the voltage value of the first pulse voltage is 1.5 to 2.5 times the operating voltage of the flash memory;

[0058] Step S3: Record the first current density value of the experimental flash memory at each moment within a preset time period; wherein, the first current density value is calculated as follows:

[0059] J = J1 + J2;

[0060] Where J is the current density value, J1 is the drift current value related to temperature T, J2 is the leakage current value of the storage layer in the flash memory, which is independent of temperature T, K is the Boltzmann constant, e is the charge of a single electron, and E i (t) represents the electric field intensity at time t, d is the distance between the plates, and a and b are constants. Φ B The electric potential energy constant;

[0061] Assuming measurements are taken for the experimental flash memory:

[0062] At preset times t1, t2, ..., t... N-1 Time, t N The first relaxation current values ​​corresponding to the time points are respectively N is the total number of moments within the preset time period during which the relaxation current value needs to be recorded.

[0063] Step S4: Record the second current density value corresponding to each moment within a preset time period of the comparison flash memory; wherein the recording interval of the second current density value is equal to that of the first current density value.

[0064] The calculation method for the second current density value is the same as that for the first current density value, and will not be repeated here.

[0065] Assuming the preset duration here is 100 seconds, measurements were taken for the control flash memory:

[0066] At preset times t1, t2, ..., t... N-1 Time, t N The second current density values ​​corresponding to the time are respectively

[0067] Step S5: Calculate the difference in current density values ​​between the experimental flash memory and the control flash memory at each moment within a preset time period; wherein, the difference in current density values ​​is the difference between the first current density value and the second current density value at the same moment.

[0068] For example, for the same preset duration, the differences in current density values ​​at different times within the preset duration are as follows:

[0069] The difference in current density at time t1 is

[0070] The difference in current density at time t2 is

[0071] …;

[0072] t N-1 The difference in current density values ​​at time t is

[0073] t N The relaxation current difference at time t is

[0074] Step S6: Construct a straight line in a rectangular coordinate system showing the change of all the current density value differences over time; wherein, in the rectangular coordinate system, the current density value difference is the y-axis and the time corresponding to the current density value difference is the x-axis.

[0075] For example, after the calculation in step S5, the difference in current density values ​​(in seconds) at each moment within a preset time period can be obtained. Then, by plotting this difference in a Cartesian coordinate system in a conventional manner, a straight line L representing the change of all current density value differences over time can be obtained. For details regarding the straight line L, please refer to [link to relevant documentation]. Figure 5 As shown;

[0076] Step S7: Calculate the slope of the obtained straight line, and use the magnitude of the correlation value that is positively correlated with the slope to characterize the data storage capability of the flash memory; wherein, the smaller the slope value, the stronger the data storage capability of the flash memory.

[0077] Based on the obtained line L, its slope can be determined. The magnitude of the correlation value, which is positively correlated with this slope, is used to characterize the data retention capacity of the flash memory; the smaller the slope value, the stronger the data retention capacity of the flash memory. Of course, the correlation value mentioned here can be the slope value or the tilt angle of the line relative to the x-axis. For example, the tilt angle of line L relative to the x-axis is...

[0078] It should be noted that in this further rapid measurement method for the data retention capacity of flash memory, the entire measurement process does not require heating equipment and can be carried out at room temperature. Furthermore, the test is fast and does not require cyclic testing at high temperatures. Moreover, during the test, the flash memory only needs to withstand 1.5 to 2.5 times the operating voltage of the flash memory, which will not cause any damage to the flash memory.

[0079] Depending on the actual measurement needs, the combined result of the flash memory data storage capacity measured in step S3 and step S7 can also be used as the measurement result of the flash memory data storage capacity. For example, the so-called "combined result" here can be a processed combination of the index value obtained in step 3 and the correlation value obtained in step S7 that is positively correlated with the slope. For example, the "combined result" can be the average between the former index value and the latter correlation value.

[0080] Although preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rapid measurement method for the data retention capacity of a flash memory, characterized in that, Includes the following steps: Step 1: Apply a preset voltage value to the flash memory at a first ambient temperature value, and measure the first current density value flowing through the flash memory at the first ambient temperature value; wherein, the first ambient temperature value is denoted as... , Within the normal operating temperature range of flash memory; Step 2: Increase the first ambient temperature value to a second ambient temperature value, apply a preset voltage value to the flash memory at the second ambient temperature value, and measure the second current density value flowing through the flash memory at the second ambient temperature value; wherein, the second ambient temperature value is denoted as... , , Within the normal operating temperature range of flash memory; Step 3: Based on the measured first current density value and second current density value, process them to obtain the index value characterizing the data storage capability of the flash memory. The first current density value is marked as The second current density value is marked as First current density value and the second current density value The calculation methods are as follows: ； ， ； in, At ambient temperature value The current density value flowing through the flash memory. It is related to the ambient temperature value The relevant drift current value, This is the leakage current value of the storage layer within the flash memory, and this leakage current value is related to the ambient temperature value. Irrelevant Boltzmann's constant, For the charge of a single electron, For a moment electric field strength, The distance between the plates. and All are constants. is the electric potential energy constant.

2. The method for rapidly measuring the data retention capacity of a flash memory according to claim 1, characterized in that, The first current density value drift current value The second current density value drift current value Among them, the unknown coefficients The calculation method is as follows: ； 。 3. The method for rapidly measuring the data retention capacity of a flash memory according to claim 2, characterized in that, The first current density value The value of the loss current in The second current density value The value of the loss current in ;in, .

4. The method for rapidly measuring the data retention capacity of a flash memory according to claim 3, characterized in that, The index value characterizing the data retention capability of the flash memory is labeled as follows: Indicator value The calculation method is as follows Among them, the performance indicators of flash memory The smaller the value, the stronger the data retention capability of the flash memory.

5. The method for rapidly measuring the data retention capacity of a flash memory according to any one of claims 1 to 4, characterized in that, After completing step 3, the data retention capacity of the flash memory is measured again according to steps S1 to S7 as follows: Step S1: Prepare the experimental device circuit and the control device circuit in advance; wherein, the experimental device circuit includes an experimental flash memory and an experimental pulse generator capable of sending pulse voltage to the experimental flash memory; the control device circuit includes a control flash memory and a control pulse generator capable of sending pulse voltage to the control flash memory; the experimental flash memory is the flash memory mentioned in steps 1 to 3. Step S2: The experimental pulse generator sends a first pulse voltage to the experimental flash memory, and the control pulse generator sends a second pulse voltage to the control flash memory; wherein the first pulse voltage and the second pulse voltage are equal in value; Step S3: Record the first current density value of the experimental flash memory at each moment within a preset time period. Step S4: Record the second current density value corresponding to each moment within a preset time period of the comparison flash memory; wherein the recording interval of the second current density value is equal to that of the first current density value. Step S5: Calculate the difference in current density values ​​between the experimental flash memory and the control flash memory at each moment within a preset time period; wherein, the difference in current density values ​​is the difference between the first current density value and the second current density value at the same moment. Step S6: Construct a straight line in a rectangular coordinate system showing the change of all the current density value differences over time; wherein, in the rectangular coordinate system, the current density value difference is the y-axis and the time corresponding to the current density value difference is the x-axis. Step S7: Calculate the slope of the obtained straight line, and use the magnitude of the correlation value that is positively correlated with the slope to characterize the data storage capability of the flash memory; wherein, the smaller the slope value, the stronger the data storage capability of the flash memory.

6. The method for rapidly measuring the data retention capacity of a flash memory according to claim 5, characterized in that, The associated value is either the slope value or the angle of inclination of the straight line relative to the x-axis.

7. The method for rapidly measuring the data retention capacity of a flash memory according to claim 5, characterized in that, The experimental pulse generator and the control pulse generator simultaneously emit pulse voltages.

8. The method for rapidly measuring the data retention capacity of a flash memory according to claim 5, characterized in that, The preset voltage value and the voltage value of the first pulse voltage are both 1.5 to 2.5 times the operating voltage of the flash memory.

9. The method for rapidly measuring the data retention capacity of a flash memory according to claim 5, characterized in that, The fusion result of the flash memory data retention capacity measured in step S3 and the flash memory data retention capacity measured in step S7 is taken as the measurement result of the flash memory data retention capacity.

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