Construction, simulation methods and equipment for MOSFET leakage current simulation model

Abstract

This application provides a method for constructing a MOSFET simulation model, a method for simulating MOSFET leakage current, and an electronic device. The model includes target simulation parameters for characterizing the relationship between the MOSFET leakage current and temperature. The method for constructing the MOSFET simulation model includes: obtaining the measured leakage current of the MOSFET at multiple test temperatures and the temperature increment of each test temperature relative to a reference temperature; fitting the relationship between the measured leakage current and the temperature increment using a monotonically increasing exponential polynomial model as the fitting model to obtain a fitting result; and assigning the fitting result to the target simulation parameters if the error between the simulated leakage current and the measured leakage current at any test temperature obtained based on the fitting result falls within a specified error range, thereby obtaining the target MOSFET simulation model. This application improves the accuracy of the MOSFET simulation model in simulating leakage current.

Description

Technical Field

[0001] The embodiments in this application relate to the field of semiconductor integrated circuit simulation modeling technology, specifically to a method for constructing a MOSFET simulation model, a method for simulating MOSFET leakage current, and an electronic device. Background Technology

[0002] In the process of integrated circuit chip design, to predict the electrical characteristics of the circuit under various operating conditions and verify the feasibility of the chip design, researchers typically use integrated circuit simulation programs (Simulation Program with Integrated Circuit Emphasis, SPICE) to simulate the operating states of the integrated circuit under various conditions before chip tape-out. The simulation results are then used to adjust the chip design or for chip manufacturing. Among the various simulation models used in integrated circuit simulation programs, the BSIM (Berkeley Short-channel IGFET Model) is widely used in the design of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) devices.

[0003] Currently, BSIM4, as the latest standard version of BSIM, can describe a variety of electrical characteristics of MOSFET devices at deep submicron and nanometer-scale process nodes. Specifically, the electrical characteristics of MOSFETs that BSIM4 can describe include current-voltage characteristics, capacitance-voltage characteristics, and temperature characteristics.

[0004] However, when researchers used BSIM4 to simulate the leakage current of MOSFETs, they found that BSIM4 had low accuracy in simulating leakage current. Summary of the Invention

[0005] In view of this, several embodiments of this application provide a method for constructing a MOSFET simulation model, a method for simulating MOSFET leakage current, and an electronic device, so as to improve the accuracy of the MOSFET simulation model in simulating the leakage current of the MOSFET.

[0006] In one aspect, an embodiment of this application provides a method for constructing a MOSFET simulation model, the MOSFET simulation model including target simulation parameters for characterizing the relationship between the leakage current of the MOSFET and temperature; the method for constructing the MOSFET simulation model includes: obtaining the measured leakage current of the MOSFET at multiple test temperatures, and the temperature increment of each test temperature relative to a reference temperature; fitting the relationship between the measured leakage current and the temperature increment using a monotonically increasing exponential polynomial model as a fitting model to obtain a fitting result; and assigning the fitting result to the target simulation parameters if the error between the simulated leakage current at any test temperature obtained based on the fitting result and the measured leakage current at the same test temperature falls within a specified error range, thereby obtaining a target MOSFET simulation model.

[0007] Optionally, the polynomial part of the exponential polynomial model is expanded into Nth-degree terms of the temperature increment up to a constant term; where N equals 4.

[0008] Optionally, the step of fitting the measured leakage current with the temperature increment using a monotonically increasing exponential polynomial model to obtain the fitting result includes: performing a logarithmic transformation on the measured leakage current to obtain the logarithm of the measured leakage current; using a univariate Nth-degree polynomial as the fitting model to fit the relationship between the logarithm of the measured leakage current and the temperature increment to obtain an exponential fitting result; and determining the fitting result based on the base, exponential coefficient, and exponential fitting result corresponding to the logarithmic transformation.

[0009] Optionally, the target simulation parameters include gate-drain sidewall junction tunneling leakage current parameters and gate-source sidewall junction tunneling leakage current parameters; in the target MOSFET simulation model, the gate-drain sidewall junction tunneling leakage current parameters and the gate-source sidewall junction tunneling leakage current parameters are assigned the same fitting result.

[0010] Optionally, the step of assigning the fitting result to the target simulation parameters to obtain a target MOSFET simulation model, where the error between the simulated leakage current at any test temperature obtained based on the fitting result and the measured leakage current at the test temperature falls within a specified error range, includes: obtaining the simulated leakage current at the plurality of test temperatures based on the fitting result; calculating the simulation error between the simulated leakage current and the measured leakage current at any of the test temperatures; verifying the continuity and monotonicity of the fitting result when the simulation error falls within a specified error range; and assigning the fitting result to the target simulation parameters when the continuity and monotonicity of the fitting result pass verification, thereby obtaining a target MOSFET simulation model.

[0011] Optionally, when the simulation error falls within a specified error range, the step of verifying the continuity and monotonicity of the fitting result includes: obtaining the verification leakage current at multiple verification temperatures based on the fitting result; wherein the temperature difference between adjacent verification temperatures is less than the temperature difference between adjacent test temperatures; verifying the continuity of the fitting result based on the verification leakage current; if the continuity of the fitting result passes verification, performing a logarithmic transformation on the verification leakage current to obtain the logarithm of the verification leakage current; and verifying the monotonicity of the fitting result based on the logarithm of the verification leakage current.

[0012] Optionally, the MOSFET simulation model is a BSIM4 model; assigning the fitting result to the target simulation parameters includes: calling the custom parameter interface of the BSIM4 model and assigning the fitting result to the target simulation parameters in the form of an external formula.

[0013] In another aspect, one embodiment of this application provides a method for simulating MOSFET leakage current, the method comprising: obtaining the operating temperature of a target MOSFET and the temperature increment of the operating temperature relative to a reference temperature; calling a MOSFET simulation model to simulate the leakage current of the target MOSFET at the operating temperature; in the MOSFET simulation model, a target simulation parameter characterizing the relationship between the leakage current of the MOSFET and temperature is defined as an exponential polynomial; the polynomial part of the exponential polynomial is expanded into Nth-degree terms of the temperature increment up to a constant term.

[0014] Optionally, N equals 4; the target simulation parameters include the gate-drain sidewall tunneling leakage current parameters and the gate-source sidewall tunneling leakage current parameters.

[0015] In another aspect, one embodiment of this application provides an electronic device, including: a memory and a processor, the memory storing a computer program executable on the processor, the processor executing the computer program to implement a method for constructing a MOSFET simulation model as described in the above embodiments, or a method for simulating MOSFET leakage current.

[0016] In several embodiments provided in this application, the measured leakage current of the MOSFET at multiple test temperatures and the temperature increment of each test temperature relative to a reference temperature are obtained. A monotonically increasing exponential polynomial model is used as the fitting model to fit the relationship between the measured leakage current and the temperature increment, and the fitting result is obtained. If the error between the simulated leakage current at any test temperature obtained based on the fitting result and the measured leakage current at the same test temperature falls within a specified error range, the fitting result is assigned to the target simulation parameters included in the MOSFET simulation model to obtain the target MOSFET simulation model. The unexpected effects achieved include: because a monotonically increasing exponential polynomial model is used as the fitting model and the relationship between the leakage current and temperature is fitted based on actual measurement data, the model of the simulated leakage current changing with temperature is closer to the actual leakage current characteristics of the MOSFET, thereby improving the simulation accuracy of the MOSFET simulation model for the leakage current of the MOSFET device at different operating temperatures. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in describing the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This diagram illustrates the comparison between simulated leakage current data and measured leakage current data obtained using the current version of BSIM4, for related technologies.

[0019] Figure 2 This is a flowchart illustrating the method for constructing a MOSFET simulation model provided in an embodiment of this application.

[0020] Figure 3 The flowchart provided in this application embodiment shows the process of fitting the relationship between the measured leakage current and the temperature increment using a monotonically increasing exponential polynomial model as the fitting model to obtain the fitting result.

[0021] Figure 4 This is a schematic diagram of the exponential fitting results provided in the embodiments of this application.

[0022] Figure 5 This is a schematic diagram illustrating the process of assigning the fitting results to the target simulation parameters, as provided in an embodiment of this application.

[0023] Figure 6 This is a schematic diagram illustrating the continuity of the fitting results based on the verification of leakage current, as provided in an embodiment of this application.

[0024] Figure 7This is a schematic diagram illustrating the monotonicity of the fitting results based on the logarithm of the leakage current, as provided in an embodiment of this application.

[0025] Figure 8 This is a flowchart illustrating the MOSFET leakage current simulation method provided in this application embodiment. Detailed Implementation

[0026] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0027] The accompanying drawings provided in this application are only schematic illustrations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component may be changed, and the layout of the components may also be more complex.

[0028] In the description of the embodiments of this application, it should be understood that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "center," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of the stated features.

[0029] Please refer to Equation 1. In the current version BSIM4 provided by the relevant technology, it is assumed that the carrier activation energy is constant, and a monotonically increasing exponential model is used to simulate the relationship between leakage current and temperature in the MOSFET off state.

[0030] Formula 1

[0031] With the continuous development of integrated circuit manufacturing technology and the shrinking of process nodes, the role of trap-assisted tunneling (TAT) mechanism is becoming increasingly prominent, which may lead to changes in the physical characteristics of integrated circuit devices. To evaluate the simulation accuracy of the current version of BSIM4 for MOSFET characteristic parameters, researchers compared the simulated leakage current data obtained using the current version of BSIM4 with the measured leakage current data.

[0032] Please see Figure 1Researchers used a channel width of 22.00... m, the channel length is 2.200 Using a MOSFET of size m as the experimental subject, the simulated leakage current data obtained using the current version of BSIM4 is represented by curves, while the measured leakage current data of the MOSFET in the off state is represented by data points. A two-dimensional coordinate system is established with temperature on the x-axis and the logarithm of the leakage current per unit width on the y-axis. The simulated and measured leakage current data are plotted on this two-dimensional coordinate system. Figure 1 It is evident that the leakage current simulation data obtained using the current version of BSIM4 cannot accurately simulate the actual leakage current measurement data's variation with temperature. Specifically, when the device operates over a wide temperature range, in the lower temperature range (below 0°C), the measured leakage current data is distributed on both sides of the simulated leakage current data. As the temperature gradually increases, the measured leakage current data is distributed on the side of the simulated leakage current data closer to the horizontal axis, and the rate of increase of the measured leakage current gradually accelerates, while the simulated leakage current data maintains a basically linear increase. Therefore, in the higher temperature range (100°C and above), there is a significant difference between the measured and simulated leakage current data.

[0033] The reason for the low accuracy of the current version of BSIM4 in simulating the relationship between MOSFET leakage current and temperature is that, since the BSIM4 model was released earlier, the statistical data used to build the BSIM4 model is based on the physical characteristics of integrated circuit devices at the early process nodes of integrated circuit manufacturing technology, and the MOSFET leakage current modeling module has not been iteratively updated for a long time.

[0034] Please refer to both Formula 1 and Formula 2. In Formula 1, , and All three parameters are exponential terms. Since all three parameters can represent temperature-related non-ideal factors, in the current version of BSIM4, the temperature-related terms are embedded linearly into the exponential model to simplify calculations and reflect the overall trend of leakage current increasing with temperature. Among these three parameters, It is directly related to the key parameter of the tunneling leakage current parameter of the gate-drain junction (JTSSWGD), which is associated with the trap-assisted tunneling current. It can be defined in the following form:

[0035] Formula 2

[0036] However, due to the influence of changes in the physical characteristics of MOSFET devices caused by the trap-assisted tunneling mechanism, or due to the limitations of the accuracy and precision of measurement equipment, the relationship between leakage current and temperature of MOSFETs at process nodes of 90nm and below no longer conforms to the exponential model.

[0037] Therefore, it is necessary to provide a method for constructing a MOSFET simulation model and a method for simulating MOSFET leakage current, so that the leakage current simulation data obtained using the MOSFET simulation model can more accurately simulate the actual change trend of MOSFET leakage current with temperature.

[0038] Please see Figure 2 One embodiment of this application provides a method for constructing a MOSFET simulation model. The MOSFET simulation model may include target simulation parameters for characterizing the relationship between the MOSFET's leakage current and temperature.

[0039] To improve the simulation accuracy of the target MOSFET simulation model while reducing the workload of constructing it, the target MOSFET simulation model can be obtained by making local adjustments to an existing MOSFET simulation model. Therefore, in this embodiment, the MOSFET simulation model can be the BSIM4 model.

[0040] Since MOSFET leakage current is greatly affected by the trap-assisted tunneling mechanism, in order to introduce the influence of this mechanism into the simulation process of the target MOSFET simulation model, in this embodiment, the target simulation parameters may include the gate-drain sidewall junction tunneling leakage current parameter (JTSSWGD) and the gate-source sidewall junction tunneling leakage current parameter (JTSSWGS).

[0041] In this embodiment, the method for constructing the MOSFET simulation model may include steps S110, S120 and S130.

[0042] S110: Obtain the measured leakage current of the MOSFET at multiple test temperatures, and the temperature increment of each test temperature relative to the reference temperature.

[0043] To improve the accuracy of the constructed target MOSFET simulation model in simulating the leakage current of the MOSFET at different operating temperatures, the leakage current of the MOSFET at different process nodes can be measured at multiple test temperatures. That is, the leakage current is measured, and the temperature increment corresponding to each of the multiple measured leakage currents is obtained, which serves as the basis for subsequent fitting.

[0044] To broaden the applicable temperature range of the target MOSFET simulation model, in this embodiment, the test temperature can be the ambient temperature set for performing electrical measurements on the MOSFET device. Specifically, the test temperature can be the typical operating temperature of the device over a wide temperature range. For example, multiple test temperatures may include -40°C, -15°C, 25°C, 85°C, and 125°C.

[0045] To broaden the range of process nodes applicable to the target MOSFET simulation model, this embodiment acquires the measured leakage current of the MOSFET at multiple test temperatures. For MOSFET devices actually manufactured at different process nodes, a semiconductor parameter analyzer can be used to measure the leakage current of the MOSFET device in the off state at each test temperature. Specifically, to achieve device size normalization, the measured leakage current can be the leakage current per unit channel width, i.e., the leakage current per unit width, and its unit can be picoamperes per micrometer (pA / μm). m).

[0046] Since the temperature dependence of some characteristic parameters in MOSFET devices is indirectly related to the operating temperature, but directly related to the deviation of the operating temperature from the reference temperature, in this embodiment, the temperature increment can be the difference between each test temperature and the reference temperature. Specifically, to match other temperature-related parameters in the MOSFET simulation model, the reference temperature can be a reference value of room temperature, i.e., 25°C. For example, corresponding to the above-mentioned multiple test temperatures, multiple temperature increments can include -65°C, -40°C, 0°C, 60°C, and 100°C.

[0047] Please refer to Table 1. Taking a MOSFET device manufactured at the 90nm process node as an example, to ensure that the measured leakage current accurately reflects the operating state of the MOSFET device, researchers performed multiple measurements of the leakage current of the MOSFET device in the off state at each test temperature. The median of the multiple measurements was used as the representative value of the measured leakage current of the MOSFET device at that test temperature. The measured leakage currents at multiple test temperatures and the corresponding temperature increments are as follows:

[0048] Table 1. Measured leakage current of MOSFET devices at multiple test temperatures under the 90nm process node

[0049]

[0050] S120: A monotonically increasing exponential polynomial model is used as the fitting model to fit the relationship between the measured leakage current and the temperature increment, and the fitting result is obtained.

[0051] To improve the simulation accuracy of the target MOSFET simulation model, researchers attempted to fit the relationship between the measured leakage current and the temperature increment using various fitting models. By comparing the fitting errors of various fitting models, it can be seen that the monotonically increasing exponential polynomial model has a smaller fitting error and a better fitting effect.

[0052] In this embodiment, the exponential polynomial model is a composite model. Specifically, the base of the exponential polynomial model is a constant, and the exponent is a polynomial. To reflect the physical characteristic that leakage current increases with increasing temperature and to improve the simulation stability of the target MOSFET simulation model, the exponential polynomial model can be a monotonically increasing model. To reduce the computational load required for local adjustments to the existing MOS-FET simulation model, the base of the exponential polynomial model can be the same as the base of the exponential model in the existing MOSFET simulation model. For example, the base of the exponential polynomial model can be 10.

[0053] For the polynomial part of this exponential polynomial model, researchers attempted to fit it using polynomials with multiple values ​​for the highest degree. Comparing the fitting errors of different highest-degree polynomials revealed that the fitting error was smaller and the fitting effect was better when the polynomial was a univariate fourth-degree polynomial. Therefore, in this embodiment, the polynomial part of the exponential polynomial model can be expanded into N-degree terms of temperature increments up to a constant term. Here, N equals 4.

[0054] Please refer to Equations 3 and 4. In this embodiment, since the target simulation parameters include two parameters: the gate-drain sidewall tunneling leakage current parameter and the gate-source sidewall tunneling leakage current parameter, the exponential polynomial model can include the following to fit the two parameters separately:

[0055] Formula 3

[0056] Formula 4

[0057] in, A fitting model can be used to fit the tunneling leakage current parameters of the gate-drain sidewall junction. A fitting model can be used to fit the tunneling leakage current parameters of the gate-source sidewall junction. , , , , , , , , , , , For the fitting parameters, This represents the temperature increment. and In this model, since each fitted parameter is a coefficient, the values ​​of the coefficients for corresponding terms can be equal or unequal. For example, and They can be equal or unequal.

[0058] Please see Figure 3 To concentrate the numerical range of the fitted data and improve the fitting accuracy, in some embodiments, a monotonically increasing exponential polynomial model is used as the fitting model to fit the relationship between the measured leakage current and the temperature increment, and the step of obtaining the fitting result may include sub-steps S121, S122 and S123.

[0059] S121: Perform a logarithmic transformation on the measured leakage current to obtain the logarithm of the measured leakage current.

[0060] Please refer to Table 2. In this embodiment, the measured leakage current can be logarithmically transformed based on the base of the exponential polynomial fitting model, converting the measured leakage current to the logarithmic domain to obtain the logarithm of the measured leakage current. For example, the measured leakage current per unit width provided in Table 1 can be logarithmically transformed with a base of 10 to obtain the following logarithm of the measured leakage current. Comparing the values ​​of the measured leakage current per unit width in Table 1 and the logarithm of the measured leakage current in Table 2, it can be seen that the value of the measured leakage current per unit width falls within the interval (0, 32.5), while the value of the logarithm of the measured leakage current falls within the interval (-2.5, 2). Therefore, the numerical range of the fitted data can be narrowed through logarithmic transformation.

[0061] Table 2. Logarithm of measured leakage current of MOSFET devices at multiple test temperatures under the 90nm process node

[0062]

[0063] S122: Using a univariate Nth-degree polynomial as the fitting model, the relationship between the logarithm of the measured leakage current and the temperature increment is fitted to obtain the exponential fitting result.

[0064] In this embodiment, N equals 4. Therefore, a univariate fourth-degree polynomial can be used as the fitting model, and a two-dimensional coordinate system can be established with the temperature increment as the abscissa and the logarithm of the measured leakage current as the ordinate. The data points representing the change of the logarithm of the measured leakage current with the temperature increment can be plotted in this two-dimensional coordinate system. Subsequently, based on these data points, an overdetermined system of equations about the coefficients of the polynomial in the fitting parameters can be established, and the least squares method can be used for optimization to determine the values ​​of the fitting parameters that minimize the sum of squared residuals.

[0065] Please see Figure 4 Taking the data in Table 2 as an example, the data points can be plotted in the two-dimensional coordinate system described above, and the formula in Formula 3 can be applied accordingly. , , , , And in Formula 4 , , , , Establish overdetermined systems of equations respectively, and calculate the results. , , , , as well as , , , , The numerical values ​​are as follows. Since MOSFET structures are typically symmetrical, researchers compared the temperature variations of the source-side leakage current and the drain-side leakage current at the 90nm process node and found that their characteristics are highly similar. Therefore, to simplify calculations and improve the robustness of the target MOSFET simulation model under different simulation conditions, in this embodiment, , , , , and , , , , In the middle, the corresponding values ​​are equal, that is, = , = , = , = , = .

[0066] In this embodiment, the exponential fitting result can be the coefficients of each term of the polynomial obtained by fitting a univariate Nth-degree polynomial fitting model. Specifically, the exponential fitting result can include N+1 fitting parameters, corresponding to the Nth-degree term to the constant term of the polynomial. For example, depending on the actual fitting situation, the exponential fitting result is... = = -1.896×10 -8 , = = 1.410×10 -6 , = = 2.608×10 -4 , = =1.095×10 -2 , = = -1.710×10 0 .

[0067] S123: Determine the fitting result based on the base, exponential coefficient, and exponential fitting result corresponding to the logarithmic transformation.

[0068] Please refer to Equations 5 and 6. In this embodiment, the fitting result can be the complete fitting model after transforming the exponential fitting result to the linear domain. Specifically, the fitting result can include the values ​​of all fitting parameters. For example, the base corresponding to the logarithmic transformation can be 10. To simplify calculations, the exponential coefficients... and They can be equal, and both are equal to 1. Based on the actual fitting situation, the fitting results are as follows:

[0069] Formula 5

[0070] Formula 6

[0071] S130: If the error between the simulated leakage current at any test temperature and the measured leakage current at the test temperature obtained based on the fitting results falls within the specified error range, the fitting results are assigned to the target simulation parameters to obtain the target MOSFET simulation model.

[0072] To ensure the physical plausibility of the target MOSFET simulation model, the fitted MOSFET simulation model obtained based on the fitting results can first be verified using Quality Assurance (QA). If the fitted MOSFET simulation model passes the verification, it can be used as the target MOSFET simulation model.

[0073] Please see Figure 5In some embodiments, the step of assigning the fitting result to the target simulation parameters to obtain the target MOSFET simulation model may include sub-steps S131, S132, S133, and S134, provided that the error between the simulated leakage current at any test temperature obtained based on the fitting result and the measured leakage current at the test temperature falls within a specified error range.

[0074] S131: Obtain the simulated leakage current at multiple test temperatures based on the fitting results.

[0075] Please refer to Equations 7 and 8. In this embodiment, the target simulation parameters in BSIM4 can be replaced with the fitting results to obtain the fitted MOSFET simulation model.

[0076] Formula 7

[0077] Formula 8

[0078] Subsequently, a fitted MOSFET simulation model is used to simulate the leakage current of the MOSFET at multiple test temperatures, obtaining the simulated leakage current at these temperatures. Specifically, to ensure the effectiveness of the comparison between the simulated and measured leakage currents, the parameters of the MOSFET device simulated for the simulated leakage current, such as structural and operational parameters, are obtained and are identical to the parameters of the MOSFET device actually measured for the measured leakage current. For example, both the MOSFET device simulated by the fitted MOSFET simulation model and the actually measured MOSFET device are based on a 90nm process node manufacturing platform. Furthermore, to achieve device size normalization, the simulated leakage current obtained based on the fitted MOSFET simulation model can be the leakage current per unit channel width, i.e., the simulated leakage current per unit width.

[0079] S132: Calculate the simulation error between the simulated leakage current and the measured leakage current at any test temperature.

[0080] Please refer to Table 3. In this embodiment, after obtaining the simulated leakage current, the difference between the measured leakage current per unit width and the simulated leakage current per unit width at each test temperature can be calculated, and the ratio of this difference to the measured leakage current per unit width can be used as the simulation error.

[0081] Table 3. Measured and simulated leakage currents of MOSFET devices at multiple test temperatures under the 90nm process node.

[0082]

[0083] S133: Verify the continuity and monotonicity of the fitting results when the simulation error falls within the specified error range.

[0084] Since an excessively small error range may cause the target MOSFET simulation model to overfit the data and lose its generalization ability, while an excessively large error range may fail to meet the simulation accuracy requirements in actual production, in order to reduce the risk of overfitting or underfitting of the target MOSFET simulation model, the specified error range can be 0.1% in this embodiment. As shown in Table 3, the simulation error falls within the specified error range at any test temperature.

[0085] In some embodiments, if the simulation error does not fall within the specified error range, the fitting parameters can be adjusted or the number of test temperatures can be increased, and the above process can be repeated until the simulation error falls within the specified error range at any test temperature.

[0086] To verify the physical rationality of the fitted MOSFET simulation model, the trend of the simulated leakage current obtained from the fitted MOSFET simulation model with temperature increments should remain consistent within the operating temperature range of the MOSFET device. Therefore, in addition to multiple test temperatures, it is also necessary to verify the relationship between the simulated leakage current obtained from the fitted MOSFET simulation model and temperature increments at temperatures other than the test temperatures within the operating temperature range of the MOSFET device.

[0087] In some embodiments, the step of verifying the continuity and monotonicity of the fitting results when the simulation error falls within a specified error range may include: obtaining the verification leakage current at multiple verification temperatures based on the fitting results; verifying the continuity of the fitting results based on the verification leakage current; performing a logarithmic transformation on the verification leakage current to obtain the logarithm of the verification leakage current when the continuity of the fitting results passes verification; and verifying the monotonicity of the fitting results based on the logarithm of the verification leakage current.

[0088] In this embodiment, to improve the reliability of the verification results for continuous verification, the temperature difference between adjacent verification temperatures can be smaller than the temperature difference between adjacent test temperatures. For example, to balance the computational load and the verification effect, the temperature difference between adjacent verification temperatures can be 5°C.

[0089] Please refer to Table 4. In this embodiment, the verification leakage current at multiple verification temperatures is obtained based on the fitting results. This verification leakage current at multiple verification temperatures can be simulated using the fitted MOSFET simulation model described in the above embodiments. Specifically, to ensure the effectiveness of verification based on the verification leakage current, the same MOSFET device simulation parameters as those used to obtain the simulated leakage current can be set based on the fitted MOSFET simulation model to obtain the verification leakage current. For example, the MOSFET device can be simulated using a 90nm process node manufacturing platform. To achieve device size normalization, the verification leakage current can be the leakage current corresponding to a unit channel width, i.e., the verification leakage current per unit width.

[0090] Table 4. Logarithm of MOSFET device leakage current at multiple verification temperatures under the 90nm process node

[0091]

[0092]

[0093] Please see Figure 6 In this embodiment, after obtaining the verification leakage current, a two-dimensional coordinate system can be established with the temperature increment as the abscissa and the verification leakage current as the ordinate. Data points representing the change of the verification leakage current with the temperature increment can then be plotted on this two-dimensional coordinate system. Figure 6 As can be seen, the data points show a continuous changing trend, meaning that the fitted MOSFET simulation model can be verified through continuity.

[0094] Please refer to Table 4 and... Figure 7 As shown in Table 4, when the verification temperature does not exceed room temperature (≤25℃), although the leakage current per unit width increases with the increase of temperature increment, it always falls within the (0, 0.02) range, and the difference between adjacent unit width verification leakage currents is small. Furthermore, since there is a 5℃ temperature difference between adjacent verification temperatures, further reducing this temperature difference may lead to a situation where some verification leakage currents increase with the increase of temperature increment, while others decrease. Therefore, further verification of the relationship between unit width verification leakage current and temperature increment is needed.

[0095] To further verify the monotonicity of the fitted MOSFET simulation model and to improve the ability to identify the trend of the unit-width verification leakage current with temperature increment within the verification temperature range not exceeding room temperature, in this embodiment, a logarithmic transformation can be performed on the verification leakage current based on the base of the exponential polynomial in the fitted MOSFET simulation model, converting the verification leakage current to the logarithmic domain to obtain the logarithm of the verification leakage current. Subsequently, a two-dimensional coordinate system can be established with the temperature increment as the abscissa and the logarithm of the verification leakage current as the ordinate, and the data points representing the change of the logarithm of the verification leakage current with temperature increment can be plotted in this two-dimensional coordinate system. For example, a logarithmic transformation can be performed on the unit-width verification leakage current provided in Table 4 above with a base of 10 to obtain the logarithm of the verification leakage current. Figure 7 It can be seen that the logarithm of the leakage current increases with the increase of temperature increment, that is, the fitted MOSFET simulation model can be verified by monotonicity.

[0096] S134: If the continuity and monotonicity of the fitting results are verified, the fitting results are assigned to the target simulation parameters to obtain the target MOSFET simulation model.

[0097] To reduce the impact of adjusting the target simulation parameters on the core architecture and other parameters of the BSIM4 model, in this embodiment, the fitting result is assigned to the target simulation parameters. This can include: calling the custom parameter interface of the BSIM4 model and assigning the fitting result to the target simulation parameters in the form of an external formula. Specifically, if the fitted MOSFET simulation model passes the continuity and monotonicity verifications, the fitted MOSFET simulation model can be directly used as the target MOSFET simulation model.

[0098] Please see Figure 8 Another embodiment of this application provides a method for simulating MOSFET leakage current. This method may include steps S210 and S220.

[0099] S210: Obtain the operating temperature of the target MOSFET and the temperature increment of the operating temperature relative to the reference temperature.

[0100] In this embodiment, the operating temperature can be the ambient temperature at which the target MOSFET is in operation. Specifically, a semiconductor parameter analyzer can be used to measure the target MOSFET to obtain its operating temperature. Subsequently, using a reference temperature of room temperature (25°C) as a base temperature, the difference between the operating temperature and the base temperature can be calculated as the temperature increment.

[0101] S220: Calls the MOSFET simulation model to simulate the leakage current of the target MOSFET at operating temperature.

[0102] In this embodiment, in the MOSFET simulation model, the target simulation parameters used to characterize the relationship between the MOSFET's leakage current and temperature are defined in exponential polynomial form. These target simulation parameters include the gate-drain sidewall tunneling leakage current parameter and the gate-source sidewall tunneling leakage current parameter. The polynomial part of the exponential polynomial is expanded into Nth-degree terms of the temperature increment up to a constant term, where N equals 4.

[0103] Another embodiment of this application provides an electronic device that may include a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it can implement the method for constructing a MOSFET simulation model or the method for simulating MOSFET leakage current as described in the above embodiments.

[0104] Another embodiment of this application provides a computer-readable storage medium on which a computer program can be stored. When executed by a processor, the computer program can implement the method for constructing a MOSFET simulation model or the method for simulating MOSFET leakage current as described in the above embodiments.

[0105] Another embodiment of this application provides a computer program product, including a computer program or computer executable instructions, which, when executed by a processor in an electronic device, can implement the MOSFET simulation model construction method or the MOSFET leakage current simulation method as described in the above embodiments.

[0106] For other technical effects of the MOSFET leakage current simulation method, electronic device, computer-readable storage medium, and computer program product described in the above embodiments, please refer to other embodiments of this application for comparison and explanation, and they will not be repeated here.

[0107] In the MOSFET simulation model construction method, MOSFET leakage current simulation method, and electronic device provided in this application embodiment, the measured leakage current of the MOSFET at multiple test temperatures and the temperature increment of each test temperature relative to the reference temperature are obtained. A monotonically increasing exponential polynomial model is used as the fitting model to fit the relationship between the measured leakage current and the temperature increment, and the fitting result is obtained. If the error between the simulated leakage current at any test temperature obtained based on the fitting result and the measured leakage current at the same test temperature falls within a specified error range, the fitting result is assigned to the target simulation parameters included in the MOS-FET simulation model to obtain the target MOSFET simulation model. The unexpected effects achieved include: since a monotonically increasing exponential polynomial model is used as the fitting model, and the polynomial part of the exponential polynomial model is a univariate fourth-degree polynomial, and the relationship between leakage current and temperature is fitted based on actual measurement data, the relationship between the simulated leakage current and temperature obtained using the target MOS-FET simulation model is closer to the actual leakage current characteristics of the MOSFET, thereby improving the simulation accuracy of the MOSFET simulation model for leakage current.

[0108] It is understood that the specific examples in this application are only intended to help those skilled in the art better understand the embodiments of this application, and are not intended to limit the scope of this application.

[0109] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not limit the implementation process of the embodiments of this application in any way.

[0110] It is understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited in this respect.

[0111] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0112] In the several embodiments provided in this application, it should be understood that the disclosed electronic devices, computer-readable storage media, and computer program products can be implemented in other ways. For example, the embodiments of the electronic devices, computer-readable storage media, and computer program products described above are merely illustrative.

[0113] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for constructing a MOSFET simulation model, characterized in that, The MOSFET simulation model includes target simulation parameters for characterizing the relationship between the MOSFET's leakage current and temperature. These target simulation parameters include gate-drain sidewall tunneling leakage current parameters and gate-source sidewall tunneling leakage current parameters. The method for constructing the MOSFET simulation model includes: Obtain the measured leakage current of the MOSFET at multiple test temperatures, and the temperature increment of each test temperature relative to a reference temperature; Using a monotonically increasing exponential polynomial model as the fitting model, the relationship between the measured leakage current and the temperature increment is fitted to obtain the fitting result. The polynomial part of the exponential polynomial model is expanded into Nth-degree terms of the temperature increment up to a constant term. If the error between the simulated leakage current at any test temperature obtained based on the fitting result and the measured leakage current at the same test temperature falls within a specified error range, the fitting result is assigned to the target simulation parameters to obtain the target MOSFET simulation model, including: Based on the fitting results, the simulated leakage current at the multiple test temperatures is obtained; Calculate the simulation error between the simulated leakage current and the measured leakage current at any of the test temperatures. Based on the fitting results, the verification leakage current at multiple verification temperatures is obtained; wherein, the temperature difference between adjacent verification temperatures is smaller than the temperature difference between adjacent test temperatures; The continuity of the fitting results is verified based on the leakage current. If the continuity of the fitting result is verified, the verification leakage current is logarithmically transformed to obtain the logarithm of the verification leakage current. The monotonicity of the fitting result is verified based on the logarithm of the leakage current. If the continuity and monotonicity of the fitting results are verified, the fitting results are assigned to the target simulation parameters to obtain the target MOSFET simulation model. The step of fitting the measured leakage current with the temperature increment using a monotonically increasing exponential polynomial model as the fitting model to obtain the fitting result includes: Perform a logarithmic transformation on the measured leakage current to obtain the logarithm of the measured leakage current; Using a univariate Nth-degree polynomial as the fitting model, the relationship between the logarithm of the measured leakage current and the temperature increment is fitted to obtain an exponential fitting result. The fitting result is determined based on the base, exponential coefficient, and exponential fitting result corresponding to the logarithmic transformation.

2. The method for constructing a MOSFET simulation model according to claim 1, characterized in that, N equals 4.

3. The method for constructing a MOSFET simulation model according to claim 1, characterized in that, In the target MOSFET simulation model, the gate-drain sidewall junction tunneling leakage current parameters and the gate-source sidewall junction tunneling leakage current parameters are assigned the same fitting result.

4. The method for constructing a MOSFET simulation model according to claim 1, characterized in that, The MOSFET simulation model is the BSIM4 model; the fitting results are assigned to the target simulation parameters, including: The custom parameter interface of the BSIM4 model is invoked to assign the fitting result to the target simulation parameters in the form of an external formula.

5. A method for simulating MOSFET leakage current, characterized in that, The method for simulating MOSFET leakage current includes: Obtain the operating temperature of the target MOSFET and the temperature increment of the operating temperature relative to a reference temperature; The MOSFET simulation model determined by any one of the construction methods in claims 1 to 4 is invoked to simulate the leakage current of the target MOSFET at the operating temperature; in the MOSFET simulation model, the target simulation parameter used to characterize the relationship between the leakage current of the MOSFET and the temperature is defined as an exponential polynomial; the polynomial part of the exponential polynomial is expanded into Nth-degree terms of the temperature increment up to a constant term.

6. The method for simulating MOSFET leakage current according to claim 5, characterized in that, N equals 4; the target simulation parameters include the gate-drain sidewall tunneling leakage current parameters and the gate-source sidewall tunneling leakage current parameters.

7. An electronic device, comprising: A memory and a processor, the memory storing a computer program executable on the processor, characterized in that, when the processor executes the computer program, it implements a method for constructing a MOSFET simulation model as described in any one of claims 1 to 4, or implements a method for simulating MOSFET leakage current as described in claim 5 or 6.

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