FDSOI device AC small signal and NBTI effect joint simulation method

Abstract

The invention discloses an FDSOI device alternating current small signal and NBTI effect joint simulation method, and relates to the technical field of semiconductor devices.The method comprises the steps that a two-dimensional device structure initial model is obtained through modeling, and the established model is calibrated; performing alternating-current small signal simulation on the calibrated model in a mixed mode to obtain a first characteristic curve reflecting alternating-current small signal characteristics; trap degradation parameters are set for the calibrated model, and the NBTI degradation condition of the device under the real condition is obtained; and performing joint simulation of the NBTI effect and the AC small signal to obtain a second characteristic curve of the AC small signal characteristic after the NBTI effect, and determining the influence of the NBTI effect on the AC small signal characteristic by comparing the two characteristic curves. Through the joint simulation method, the convergence is improved, and meanwhile, the influence of the NBTI effect on the alternating current small signal characteristic can be accurately reflected through the calibrated device structure and degradation parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a method for jointly simulating small AC signals and NBTI (Negative bias temperature instability) effects of a FDSOI (fully depleted silicon on insulator) device. Background Art

[0002] In recent years, the semiconductor integrated circuit industry has developed rapidly, the device size has been continuously reduced, and the thickness of the gate oxide layer has been continuously reduced. The reliability problems of devices have become more and more serious, including negative bias temperature instability (NBTI), hot carrier injection (HCI), total dose effect (TID) and time-dependent breakdown (TDDB). The NBTI effect has become the main reliability problem in CMOS (Complementary Metal Oxide Semiconductor) technology and will have a certain impact on the service life of the device. Therefore, the study of the NBTI effect has become increasingly important.

[0003] At present, FDSOI devices have been widely used. Compared with bulk silicon devices, FDSOI devices can enhance gate control capability and reduce gate leakage current, and have the characteristics of lower power consumption. Studies have shown that the NBTI effect of FDSOI devices is more serious than that of bulk silicon devices. Because FDSOI devices have a buried oxide layer, they will cause self-heating effect when NBTI stress acts, causing the internal temperature of the device to rise, thereby aggravating the NBTI degradation of the device. In RF integrated circuits, when the channel length is reduced to 100nm, the traditional bulk silicon CMOS technology can no longer meet the requirements of the RF integrated circuit market. Compared with traditional CMOS technology, FDSOI can better reduce parasitic capacitance, latch-up effect, etc., and enhance the isolation between various devices. Therefore, FDSOI devices have replaced bulk silicon devices of CMOS technology in nano RF integrated circuits.

[0004] Most of the current research focuses on the impact of NBTI effects on DC characteristics (such as threshold voltage, leakage current, etc.), but does not explain the impact on AC small signal characteristics. In addition, if a trap degradation model is added to the physical model during AC small signal simulation, the simulation will not converge. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a joint simulation method of AC small signal and NBTI effect of FDSOI device. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0006] The present invention provides a method for jointly simulating small AC signals and NBTI effects of FDSOI devices, comprising:

[0007] The initial model of the two-dimensional device structure was established;

[0008] Correcting model parameters of the two-dimensional device structure initial model to obtain a two-dimensional device structure calibration model;

[0009] Performing an AC small signal simulation on the two-dimensional device structure calibration model in sdevice to obtain a first characteristic curve;

[0010] Using the trap physics model to set the NBTI effect on the two-dimensional device structure calibration model, and by correcting the degradation parameters of the trap physics model, obtaining a calibrated NBTI degradation model that is the same as the actual NBTI degradation of the device;

[0011] Based on the device instantaneous simulation state of the calibration NBTI degradation model, performing a joint simulation of an AC small signal and NBTI effect on the two-dimensional device structure calibration model in sdevice to obtain a second characteristic curve;

[0012] According to the first characteristic curve and the second characteristic curve, the influence of the NBTI effect on the AC small signal characteristic of the device is determined.

[0013] In one embodiment of the present invention, the established two-dimensional device structure initial model includes:

[0014] Based on the device structure parameters and the sde tool of TCAD simulation software, an initial model of the two-dimensional device structure of the FDSOI device is established; the device structure parameters include: device geometry, size, doping concentration and grid density.

[0015] In one embodiment of the present invention, the model parameters of the two-dimensional device structure initial model are corrected to obtain a two-dimensional device structure calibration model, including:

[0016] A transfer characteristic curve of the initial model of the two-dimensional device structure is obtained by static scanning, with the gate voltage as the abscissa and the drain current as the ordinate;

[0017] According to the difference between the transfer characteristic curve of the two-dimensional device structure initial model and the device's real transfer characteristic curve, the model parameters of the two-dimensional device structure initial model are corrected to obtain a two-dimensional device structure calibration model that is identical to the device's real transfer characteristic curve.

[0018] In one embodiment of the present invention, the model parameters include: gate work function, source and drain doping concentration, channel doping concentration and LDD doping concentration.

[0019] In one embodiment of the present invention, performing an AC small signal simulation on the two-dimensional device structure calibration model in sdevice to obtain a first characteristic curve includes:

[0020] The device part of the two-dimensional device structure calibration model is defined in sdevice, and the two-dimensional device structure calibration model and the corresponding physical model are loaded into the device part; the physical model includes: SRH model, high field velocity saturation model and carrier scattering model;

[0021] Define the circuit system part for AC small signal simulation in sdevice;

[0022] In the solve section of sdevice, set the coupled section and the AC coupled section and perform a static scan to implement small AC signal simulation.

[0023] The svisual tool is used to extract the AC small signal simulation results in sdevice to obtain the first characteristic curve.

[0024] In one embodiment of the present invention, the coupled part includes: a gate scanning voltage and a drain voltage of the two-dimensional device structure calibration model;

[0025] The AC coupled portion includes a scan start frequency, a scan end frequency, a number of scan points within a scan frequency range, and a pattern of changes in the scan frequency.

[0026] In one embodiment of the present invention, the NBTI effect is set for the two-dimensional device structure calibration model using a trap physics model, and a calibration NBTI degradation model identical to the actual NBTI degradation of the device is obtained by correcting the degradation parameters of the trap physics model, including:

[0027] Adding the trap physical model into TCAD simulation software and setting degradation parameters of the trap physical model;

[0028] Adding a Temperature keyword to the Device part of the two-dimensional device structure calibration model to set temperature parameters and bias state of the device;

[0029] Performing a static scan on the two-dimensional device structure calibration model, and extracting a threshold voltage variation curve of the two-dimensional device structure calibration model using a svisual tool;

[0030] According to the difference between the threshold voltage variation curve of the two-dimensional device structure calibration model and the actual threshold voltage variation curve of the device, by correcting the degradation parameter, a calibration NBTI degradation model identical to the actual threshold voltage variation curve of the device is obtained;

[0031] Based on the calibrated NBTI degradation model, a transient simulation of NBTI effect is performed on the two-dimensional device structure calibration model to obtain a transient simulation state of the device and save it in a state file.

[0032] In one embodiment of the present invention, the degradation parameters include: the diffusion coefficient of hydrogen in the oxide layer, the H diffusion activation energy, the initial concentration of hydrogen at the interface, the depassivation constant, the concentration of initial Si-H bonds, the activation energy of Si-H bond breaking, and the concentration of all unbroken Si-H bonds at the interface.

[0033] In one embodiment of the present invention, based on the device instantaneous simulation state of the calibration NBTI degradation model, the two-dimensional device structure calibration model is subjected to a joint simulation of an AC small signal and NBTI effect in sdevice to obtain a second characteristic curve, including:

[0034] The state file and the calibrated NBTI degradation model are added to the Device part of the two-dimensional device structure calibration model for AC small signal simulation, and the AC small signal and NBTI effect joint simulation of the two-dimensional device structure calibration model is realized through static scanning. The joint simulation results of the AC small signal and NBTI effect in sdevice are extracted using the svisual tool to obtain the second characteristic curve.

[0035] In one embodiment of the present invention, determining the influence of the NBTI effect on the AC small signal characteristics of the device according to the first characteristic curve and the second characteristic curve includes:

[0036] The first characteristic curve and the second characteristic curve are compared, and the influence of the NBTI effect on the AC small signal characteristics of the device is determined according to the comparison results of the characteristic frequencies, the maximum oscillation frequencies and the capacitance changes of the gate of the two characteristic curves.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The FDSOI device AC small signal and NBTI effect joint simulation method of the present invention comprises: establishing an initial model of a two-dimensional device structure; correcting model parameters of the initial model of the two-dimensional device structure to obtain a calibration model of the two-dimensional device structure; performing AC small signal simulation on the calibration model of the two-dimensional device structure in sdevice to obtain a first characteristic curve; using a trap physics model to set the NBTI effect on the calibration model of the two-dimensional device structure, and by correcting the degradation parameters of the trap physics model, obtaining a calibrated NBTI degradation model that is the same as the actual NBTI degradation of the device; based on the device instantaneous simulation state of the calibrated NBTI degradation model, performing AC small signal and NBTI effect joint simulation on the calibration model of the two-dimensional device structure in sdevice to obtain a second characteristic curve; according to the first characteristic curve and the second characteristic curve, determining the influence of the NBTI effect on the AC small signal characteristics of the device. In the present invention, the convergence is improved by the joint simulation method, and the influence of the NBTI effect on the AC small signal characteristics can be accurately reflected by the calibrated device structure and degradation parameters.

[0039] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a flow chart of a method for jointly simulating an AC small signal and NBTI effect of an FDSOI device provided by an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of an initial model of a two-dimensional device structure of FDSOIPMOS established by TCAD simulation software provided in an embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of a transfer characteristic curve of a calibration model of a two-dimensional device structure and a real transfer characteristic curve of a device provided by an embodiment of the present invention;

[0043] Figure 4 It is a schematic diagram of a threshold voltage variation curve of a two-dimensional device structure calibration model provided by an embodiment of the present invention under a calibration NBTI degradation model and a real threshold voltage variation curve of the device;

[0044] Figure 5 It is a schematic diagram of simulation results of the change of current gain (|H21| parameter) with frequency under different gate voltages of the device provided by an embodiment of the present invention before and after being acted upon by NBTI;

[0045] Figure 6 It is a schematic diagram of simulation results of changes in characteristic frequency of a device provided by an embodiment of the present invention with gate voltage before and after being acted upon by NBTI;

[0046] Figure 7 It is a schematic diagram of simulation results of the unilateral power gain of the device provided by the embodiment of the present invention before and after being affected by NBTI in the same coordinate system;

[0047] Figure 8 It is a schematic diagram of simulation results of changes in the maximum oscillation frequency of the device provided by an embodiment of the present invention with the gate voltage before and after being affected by NBTI. DETAILED DESCRIPTION

[0048] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, a method for jointly simulating the AC small signal and NBTI effect of an FDSOI device proposed in accordance with the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0049] The above and other technical contents, features and effects of the present invention are clearly presented in the following detailed description of the specific implementation modes in conjunction with the accompanying drawings. Through the description of the specific implementation modes, the technical means and effects adopted by the present invention to achieve the predetermined purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and explanation purposes and are not used to limit the technical solutions of the present invention.

[0050] The embodiment of the present invention provides a method for jointly simulating the AC small signal and NBTI effect of an FDSOI device. The simulation method is implemented based on the Sentaurus TCAD simulation software. Figure 1 , Figure 1 FIG. 1 is a flow chart of a method for jointly simulating an AC small signal and NBTI effect of an FDSOI device provided in an embodiment of the present invention. Figure 1 As shown, the FDSOI device AC small signal and NBTI effect joint simulation method of this embodiment includes:

[0051] Step 1: Establish the initial model of the two-dimensional device structure.

[0052] In an optional embodiment, step 1 includes: establishing an initial two-dimensional device structure model of the FDSOI device based on device structure parameters and an SDE tool of TCAD simulation software.

[0053] Optionally, the device structure parameters include: device geometry, size, doping concentration and grid density.

[0054] For example, the structure diagram of the initial model of the two-dimensional structure device of FDSOIPMOS is established by using the SDE tool of TCAD simulation software as shown in FIG. Figure 2 As shown, Figure 2 FIG. 1 is a schematic diagram of an initial model of a two-dimensional device structure of FDSOIPMOS established by TCAD simulation software provided in an embodiment of the present invention. Figure 2 It can be seen that the initial model of the two-dimensional structure device includes, from bottom to top, the substrate, the back gate doping layer, the buried layer, the source terminal, the drain terminal and the channel region, wherein the source terminal, the drain terminal and the channel region are located above the buried layer, and there is also a gate oxide layer above the channel region, with side walls on both sides of the gate oxide layer. Figure 2 The numbers and color areas in the substrate indicate the doping concentrations corresponding to the colors of the corresponding layers in the device.

[0055] Step 2: Correct the model parameters of the initial model of the two-dimensional device structure to obtain a calibration model of the two-dimensional device structure;

[0056] In an optional embodiment, step 2 includes:

[0057] Step 2.1: Using static scanning to obtain a transfer characteristic curve of the initial model of the two-dimensional device structure with the gate voltage as the abscissa and the drain current as the ordinate;

[0058] Step 2.2: According to the difference between the transfer characteristic curve of the two-dimensional device structure initial model and the device's actual transfer characteristic curve, the model parameters of the two-dimensional device structure initial model are corrected to obtain a two-dimensional device structure calibration model that is the same as the device's actual transfer characteristic curve.

[0059] The model parameters include: gate work function, source and drain doping concentration, channel doping concentration and LDD (lightly doped drain) doping concentration.

[0060] Specifically, in this embodiment, during static scanning, the source, drain, gate and substrate grounding of the initial model of the two-dimensional device structure are set to 0V, and then the gate voltage is scanned to -0.9V, and then the drain voltage is scanned to -0.9V, to obtain a transfer characteristic curve of the initial model of the two-dimensional device structure with the gate voltage as the horizontal coordinate and the drain current as the vertical coordinate, and the actual transfer characteristic curve of the device is compared with the transfer characteristic curve of the initial model of the two-dimensional device structure, and according to the difference between the two curves, the gate work function, source and drain doping, channel doping and LDD doping of the initial model of the two-dimensional device structure are adjusted, and the adjusted device model is continuously subjected to static scanning to obtain a new transfer characteristic curve, which is then compared with the actual transfer characteristic curve of the device, and the static scanning and model parameter adjustment process is repeated until a two-dimensional device structure model that coincides with the actual transfer characteristic curve of the device is obtained as a two-dimensional device structure calibration model.

[0061] For example, the model parameters of the two-dimensional device structure calibration model of FDSOIPMOS are shown in Table 1. Figure 3 , Figure 3 is a schematic diagram of a transfer characteristic curve of a two-dimensional device structure calibration model and a device real transfer characteristic curve provided by an embodiment of the present invention, Figure 3 It can be seen that the transfer characteristic curve of the calibrated two-dimensional device structure calibration model is basically consistent with the actual transfer characteristic curve of the device.

[0062] Table 1

[0063] Channel length (nm) 22 Gate oxide thickness (nm) 0.9 <![CDATA[Source-drain Gaussian doping peak (cm -3 )]]> <![CDATA[1×10 19 ]]> <![CDATA[Source-drain Gaussian doping concentration (cm -3 )]]> <![CDATA[4×10 16 ]]> <![CDATA[Source-drain LDD Gaussian doping peak (cm -3 )]]> <![CDATA[1×10 18 ]]> <![CDATA[Source-drain LDD Gaussian doping concentration (cm -3 )]]> <![CDATA[1×10 16 ]]> <![CDATA[Channel doping concentration (cm -3 )]]> <![CDATA[1×10 15 ]]> <![CDATA[Substrate doping concentration (cm -3 )]]> <![CDATA[1.2×10 15 ]]> Gate work function 4.64

[0064] Step 3: Perform AC small signal simulation on the two-dimensional device structure calibration model in sdevice to obtain a first characteristic curve.

[0065] In an optional embodiment, step 3 includes:

[0066] Step 3.1: Define the Device part of the two-dimensional device structure calibration model in sdevice, and load the two-dimensional device structure calibration model and the corresponding physical model into the Device part.

[0067] In this embodiment, the physical model includes: an SRH model, a high field velocity saturation model, and an inter-carrier scattering model.

[0068] Specifically, first add the two-dimensional device structure calibration model to the Device part, and set the File, Electrode, plot and Physics parts in the Device part, where File includes the added two-dimensional device structure calibration model, Physics includes the physical model corresponding to the two-dimensional device structure calibration model, and Electro includes the electrode.

[0069] Step 3.2: Define the circuit system part for AC small signal simulation in sdevice.

[0070] In this embodiment, the source, drain, substrate, and gate of the device are numbered s, d, b, and g, respectively, and the four ports are connected to a DC voltage source and set to 0V. The setting command statement is as follows:

[0071] PMOS pmos(gate=g drain=d source=s substrate=b)

[0072] Vsource_pset vg(g 0){dc=0}

[0073] Vsource_pset vd(d 0){dc=0}

[0074] Vsource_pset vs(s 0){dc=0}

[0075] Vsource_pset vb(b 0){dc=0}

[0076] It is worth noting that in order to make the curve of the small AC signal more accurate, the gate (g end) and the source (s end), the drain (d end) and the source (s end) are connected to the corresponding resistors. Be careful not to add a resistor directly between the gate and the drain, which will cause inaccurate results. In this embodiment, the resistor value added is 10 5 Ω.

[0077] Step 3.3: Set the coupled part and the AC coupled part in the solve section of sdevice and perform a static scan to implement small AC signal simulation.

[0078] Optionally, the coupled part includes: a gate scanning voltage and a drain voltage of a two-dimensional device structure calibration model.

[0079] In this embodiment, the gate scanning voltage Vgs of the two-dimensional device structure calibration model is set to scan from 0 to -1V, and the drain voltage VD is set to -0.2V.

[0080] Optionally, the ac coupled portion includes a sweep start frequency, a sweep end frequency, a number of sweep points within the sweep frequency range, and a sweep frequency variation pattern.

[0081] In this embodiment, the scanning start frequency is set to 10 7 Hz, the sweep end frequency is set to 10 14 Hz, the number of scanning points within the scanning frequency range is set to 40, the changing rule of the scanning frequency is set to Exclude and the attenuation mode is set to Decade.

[0082] Step 3.4: Use the svisual tool to extract the AC small signal simulation results in sdevice to obtain the first characteristic curve.

[0083] In this embodiment, after extracting the AC small signal characteristic parameters in the AC small signal simulation results in sdevice using the svisual tool, a corresponding change curve can be drawn to obtain a first characteristic curve, that is, a characteristic curve of the AC small signal response of the device without NBTI effect.

[0084] Step 4: Use the trap physics model to set the NBTI effect on the two-dimensional device structure calibration model. By correcting the degradation parameters of the trap physics model, a calibrated NBTI degradation model that is the same as the actual NBTI degradation of the device is obtained.

[0085] In an optional embodiment, step 4 includes:

[0086] Step 4.1: Add the trap physical model to the TCAD simulation software and set the degradation parameters of the trap physical model;

[0087] Step 4.2: Add the Temperature keyword to the Device part of the two-dimensional device structure calibration model to set the temperature parameters and the bias state of the device;

[0088] Step 4.3: Perform a static scan on the two-dimensional device structure calibration model, and use the svisual tool to extract the threshold voltage change curve of the two-dimensional device structure calibration model;

[0089] Step 4.4: According to the difference between the threshold voltage variation curve of the two-dimensional device structure calibration model and the actual threshold voltage variation curve of the device, the degradation parameter is corrected to obtain a calibration NBTI degradation model that is the same as the actual threshold voltage variation curve of the device;

[0090] Step 4.5: Based on the calibrated NBTI degradation model, perform a transient simulation of the NBTI effect on the two-dimensional device structure calibration model, obtain the device transient simulation state and save it in a state file.

[0091] In this embodiment, the trap physics model is used to perform NBTI effect simulation.

[0092] Optionally, the trap physics model may adopt a trap degradation model (TDM), which is a model developed based on reaction-diffusion theory and is used to simulate the process of Si-H bond breaking to form traps and trap capture charges to form trapped charges at the device interface during NBTI stress.

[0093] In this embodiment, the degradation parameters of TDM include: the diffusion coefficient D of hydrogen in the oxide layer 0 , H diffusion activation energy ε H , the initial concentration of hydrogen at the interface Depassivation constant v 0 , the initial Si-H bond concentration Activation energy of Si-H bond cleavage The concentration of all unbroken Si-H bonds at the interface is N. Among them, the activation energy of the electric field strength on the breaking of Si-H bonds is The degree of influence of ρ, β ⊥These three constant parameters determine.

[0094] Exemplarily, the set trap physical model, that is, the degradation parameter values ​​of TDM are shown in Table 2.

[0095] Table 2

[0096]

[0097] In this embodiment, the Temperature keyword is added to the Physics section, the temperature parameter is set to 125°C, and the bias state of the device is set to add a -1.8V bias voltage to the gate.

[0098] Specifically, in this embodiment, after the trap physical model and its degradation parameters, temperature parameters and bias state are set, the two-dimensional device structure calibration model is quasi-statically scanned to obtain the corresponding transfer characteristic curve after the NBTI effect, and then the threshold voltage change percentage is extracted from the transfer characteristic curve using the svisual tool to obtain the threshold voltage change curve, and the threshold voltage change curve is compared with the device's real threshold voltage change curve. According to the difference between the two curves, the degradation parameters of the trap physical model are changed, and the device model after the degradation parameters are adjusted is continuously statically scanned to obtain a new threshold voltage change curve, which is then compared with the device's real threshold voltage change curve. The static scanning and degradation parameter adjustment process is cyclically performed until it coincides with the device's real threshold voltage change curve. At this time, the trap physical model is the calibrated NBTI degradation model. Finally, based on the calibrated NBTI degradation model, the NBTI effect transient simulation is performed on the two-dimensional device structure calibration model to obtain the device transient simulation state and save it in the state file.

[0099] Optionally, based on the calibrated NBTI degradation model, a transient simulation of NBTI effect may be performed on the two-dimensional device structure calibration model for 3000 seconds, and the transient simulation state of the device after 3000 seconds may be saved using a save statement and a plot statement.

[0100] See also Figure 4 , Figure 4 FIG. 1 is a schematic diagram of a threshold voltage variation curve of a two-dimensional device structure calibration model provided by an embodiment of the present invention under a calibration NBTI degradation model and a true threshold voltage variation curve of a device. Figure 4 It can be seen that the threshold voltage change curve of the two-dimensional device structure calibration model under the calibration NBTI degradation model is basically consistent with the device threshold voltage change curve.

[0101] Step 5: Based on the device instantaneous simulation state of the calibrated NBTI degradation model, perform a joint simulation of the AC small signal and the NBTI effect on the two-dimensional device structure calibration model in sdevice to obtain a second characteristic curve.

[0102] In an optional embodiment, step 5 includes:

[0103] The state file and the calibrated NBTI degradation model are added to the Device part of the two-dimensional device structure calibration model for AC small signal simulation. The AC small signal and NBTI effect joint simulation of the two-dimensional device structure calibration model is realized through static scanning. The svisual tool is used to extract the joint simulation results of the AC small signal and NBTI effect in sdevice to obtain the second characteristic curve.

[0104] In this embodiment, the state files in step 4 are saved as files with suffixes of .tdr and .sav, respectively, and these files are used to set the File part of the Device part of the AC small signal simulation of the two-dimensional device structure calibration model, wherein the specific command statement is:

[0105] Grid = "file name.tdr"

[0106] Load = "file name.sav"

[0107] Doping = "file name.tdr"

[0108] It should be noted that when importing a file, the file name must be consistent with the file name saved in step 4, and the trap physical model settings in the Physics section of the Device section must be exactly the same as the degradation parameters set for the NBTI effect to ensure that the saved file can be imported normally. If the traps are inconsistent, the import will fail.

[0109] In this embodiment, after extracting the AC small signal characteristic parameters in the joint simulation results of the AC small signal and NBTI effect in sdevice using the svisual tool, a corresponding change curve can be drawn to obtain a second characteristic curve, that is, a characteristic curve of the AC small signal response of the device after the NBTI effect.

[0110] Step 6: According to the first characteristic curve and the second characteristic curve, determine the influence of the NBTI effect on the AC small signal characteristics of the device.

[0111] In an optional embodiment, step 6 includes:

[0112] The first characteristic curve and the second characteristic curve are compared, and the influence of the NBTI effect on the AC small signal characteristics of the device is determined according to the comparison results of the characteristic frequencies, the maximum oscillation frequencies and the capacitance changes of the gate of the two characteristic curves.

[0113] Taking the two-dimensional device structure calibration model of FDSOIPMOS as an example, if the characteristic frequency curve extracted in step 3 is above the characteristic frequency curve extracted in step 5; or the maximum oscillation frequency curve extracted in step 3 is above the maximum oscillation frequency curve extracted in step 5, then the NBTI effect deteriorates the AC small signal characteristics of the FDSOIPMOS field effect tube. If the characteristic frequency curve extracted in step 3 is below the characteristic frequency curve extracted in step 5; or the maximum oscillation frequency curve extracted in step 3 is below the maximum oscillation frequency curve extracted in step 5, then the NBTI effect improves the AC small signal characteristics of the FDSOIPMOS field effect tube.

[0114] Further, taking the 2D device structure calibration model of FDSOIPMOS as an example, the results of comparing the first characteristic curve and the second characteristic curve can be found in Figure 5-Figure 8 . Figure 5 It is a schematic diagram of simulation results of the change of current gain (|H21| parameter) with frequency under different gate voltages of the device provided by an embodiment of the present invention before and after being acted upon by NBTI; Figure 6 It is a schematic diagram of simulation results of changes in characteristic frequency of a device provided by an embodiment of the present invention with gate voltage before and after being acted upon by NBTI; Figure 7 It is a schematic diagram of simulation results of the unilateral power gain of the device provided by the embodiment of the present invention before and after being affected by NBTI in the same coordinate system; Figure 8 It is a schematic diagram of the simulation results of the maximum oscillation frequency of the device provided by the embodiment of the present invention before and after NBTI as the gate voltage changes. The characteristic frequency is inferred by the current gain, and the maximum oscillation frequency is inferred by the unilateral power gain. The second characteristic curve of the AC small signal is significantly deteriorated. Therefore, the NBTI effect deteriorates the AC small signal characteristics.

[0115] The FDSOI device AC small signal and NBTI effect joint simulation method of the present invention improves convergence through the joint simulation method, and can accurately reflect the influence of the NBTI effect on the AC small signal characteristics through the calibrated device structure and degradation parameters.

[0116] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant is intended to cover non-exclusive inclusion, so that the article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the article or device including the elements. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The orientation or position relationship indicated by "up", "down", "left", "right", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0117] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A joint simulation method for AC small signal and NBTI effect of FDSOI device, characterized in that: include: The initial model of the two-dimensional device structure was established; Correcting model parameters of the two-dimensional device structure initial model to obtain a two-dimensional device structure calibration model; Performing an AC small signal simulation on the two-dimensional device structure calibration model in sdevice to obtain a first characteristic curve; Using the trap physics model to set the NBTI effect on the two-dimensional device structure calibration model, and by correcting the degradation parameters of the trap physics model, obtaining a calibrated NBTI degradation model that is the same as the actual NBTI degradation of the device; Based on the device instantaneous simulation state of the calibration NBTI degradation model, performing a joint simulation of an AC small signal and NBTI effect on the two-dimensional device structure calibration model in sdevice to obtain a second characteristic curve; According to the first characteristic curve and the second characteristic curve, the influence of the NBTI effect on the AC small signal characteristic of the device is determined.

2. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 1, characterized in that: The initial model of the two-dimensional device structure was established, including: Based on the device structure parameters and the sde tool of TCAD simulation software, an initial model of the two-dimensional device structure of the FDSOI device is established; the device structure parameters include: device geometry, size, doping concentration and grid density.

3. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 1, characterized in that: Correcting the model parameters of the two-dimensional device structure initial model to obtain a two-dimensional device structure calibration model, including: A transfer characteristic curve of the initial model of the two-dimensional device structure is obtained by static scanning, with the gate voltage as the abscissa and the drain current as the ordinate; According to the difference between the transfer characteristic curve of the two-dimensional device structure initial model and the device's real transfer characteristic curve, the model parameters of the two-dimensional device structure initial model are corrected to obtain a two-dimensional device structure calibration model that is identical to the device's real transfer characteristic curve.

4. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 3 is characterized in that: The model parameters include: gate work function, source and drain doping concentration, channel doping concentration and LDD doping concentration.

5. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 1, characterized in that: Performing an AC small signal simulation on the two-dimensional device structure calibration model in sdevice to obtain a first characteristic curve, including: The device part of the two-dimensional device structure calibration model is defined in sdevice, and the two-dimensional device structure calibration model and the corresponding physical model are loaded into the device part; the physical model includes: SRH model, high field velocity saturation model and carrier scattering model; Define the circuit system part for AC small signal simulation in sdevice; In the solve section of sdevice, set the coupled section and the AC coupled section and perform a static scan to implement small AC signal simulation. The svisual tool is used to extract the AC small signal simulation results in sdevice to obtain the first characteristic curve.

6. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 5, characterized in that: The coupled part includes: a gate scanning voltage and a drain voltage of the two-dimensional device structure calibration model; The AC coupled portion includes a scan start frequency, a scan end frequency, a number of scan points within a scan frequency range, and a pattern of changes in the scan frequency.

7. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 5, characterized in that: The NBTI effect is set for the two-dimensional device structure calibration model by using the trap physics model, and a calibration NBTI degradation model identical to the actual NBTI degradation of the device is obtained by correcting the degradation parameters of the trap physics model, including: Adding the trap physical model into TCAD simulation software and setting degradation parameters of the trap physical model; Adding a Temperature keyword to the Device part of the two-dimensional device structure calibration model to set temperature parameters and bias state of the device; Performing a static scan on the two-dimensional device structure calibration model, and extracting a threshold voltage variation curve of the two-dimensional device structure calibration model using a svisual tool; According to the difference between the threshold voltage variation curve of the two-dimensional device structure calibration model and the actual threshold voltage variation curve of the device, by correcting the degradation parameter, a calibration NBTI degradation model identical to the actual threshold voltage variation curve of the device is obtained; Based on the calibrated NBTI degradation model, a transient simulation of NBTI effect is performed on the two-dimensional device structure calibration model to obtain a transient simulation state of the device and save it in a state file.

8. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 7, characterized in that: The degradation parameters include: diffusion coefficient of hydrogen in the oxide layer, H diffusion activation energy, initial concentration of hydrogen at the interface, depassivation constant, initial Si-H bond concentration, activation energy of Si-H bond breaking, and concentration of all unbroken Si-H bonds at the interface.

9. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 7, characterized in that: Based on the device instantaneous simulation state of the calibrated NBTI degradation model, the two-dimensional device structure calibration model is jointly simulated with an AC small signal and an NBTI effect in sdevice to obtain a second characteristic curve, including: The state file and the calibrated NBTI degradation model are added to the Device part of the two-dimensional device structure calibration model for AC small signal simulation, and the AC small signal and NBTI effect joint simulation of the two-dimensional device structure calibration model is realized through static scanning. The joint simulation results of the AC small signal and NBTI effect in sdevice are extracted using the svisual tool to obtain the second characteristic curve.

10. The FDSOI device AC small signal and NBTI effect joint simulation method according to claim 1, characterized in that: Determining the influence of the NBTI effect on the AC small signal characteristics of the device according to the first characteristic curve and the second characteristic curve includes: The first characteristic curve and the second characteristic curve are compared, and the influence of the NBTI effect on the AC small signal characteristics of the device is determined according to the comparison results of the characteristic frequencies, the maximum oscillation frequencies and the capacitance changes of the gate of the two characteristic curves.

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