Five-tube OTA total dose effect modeling simulation method

Abstract

The invention discloses a five-tube OTA total dose effect modeling simulation method. The method comprises the following steps: step 1, building a five-tube OTA circuit by using 130nm PDSOI and Cadence EDA, and obtaining quiescent working point information of an input pair tube and a current mirror tube and a transfer curve before total dose irradiation; step 2, extracting parameters of the BSIMSOI V4.2, and carrying out 3D modeling by using sde; step 3, using Sdevice to calibrate the 3D model, adding an irradiation model, and simulating to obtain a total dose post-irradiation transfer curve; step 4, the BSIMSOI V4.2 is trimmed, a total dose post-irradiation transfer curve is obtained by using Spectre, and post-irradiation transfer curve fitting is carried out; 5, repeating the step 4 until curve fitting convergence; and step 6, obtaining a total dose effect influence result by using Spectre. According to the method, the problems that TCAD is long in circuit-level total dose irradiation simulation time and difficult to converge are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and in particular relates to a modeling and simulation method for a five-tube OTA total dose effect. Background Art

[0002] The diverse high-energy radiation and particles in the space radiation environment can degrade the performance of integrated circuit devices and induce total ionizing dose (TID), single event effects (SEE), and dose-rate effects. Compared to bulk silicon technology, silicon-on-insulator (SOI) technology incorporates a buried oxide (BOX) layer, making it less sensitive to SEE and dose-rate effects. However, the BOX layer in SOI technology traps positive charges induced by TID and interacts with trapped charges in shallow trench isolation (STI). Furthermore, TID also induces Si-SiO2 interface states, complicating and exacerbating the total dose effects of SOI devices.

[0003] Total dose effect (TID) refers to the generation and separation of electron-hole pairs in the oxide layer of semiconductor devices under prolonged ionizing radiation exposure. This leads to the capture of holes within the oxide layer or at the interface, resulting in the accumulation of positive charge in the gate oxide layer and the generation of interface states. This can cause device parameter degradation such as threshold voltage drift, increased leakage current, and decreased transconductance. In severe cases, it can lead to device failure. The extent of this effect depends on multiple factors, including total radiation dose, dose rate, device process structure, radiation bias, and temperature. It is widely present in radiation environments such as space, nuclear industry, and high-energy physics, and is a key consideration in the radiation hardening design of electronic systems.

[0004] Five-transistor OTAs are fundamental and critical modules in analog circuits. In particular, their two-stage op amps, formed as the first stage and with a common-source stage as the second stage, are widely used in power supply circuits such as bandgap references and low-dropout linear regulators. Silicon-on-insulator (SOI) technology is inherently resistant to single-event effects, leading to its widespread use in memory circuits for space applications. However, the power modules powering these memory circuits are also made using SOI technology, making them more sensitive to total dose effects. Therefore, it is crucial to simulate the total dose effects of five-transistor OTAs at the circuit level and predict their tolerance to total dose effects. However, performing total dose circuit-level irradiation simulations directly within the semiconductor process and device simulation software TCAD is limited by long simulation times and difficulty in convergence. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a five-tube OTA total dose effect modeling and simulation method. The technical problem to be solved by the present invention is achieved through the following technical solutions: An embodiment of the present invention provides a five-tube OTA total dose effect modeling and simulation method, including: Step 1: Based on the 130nm PDSOI process library and Cadence EDA tools, a five-transistor OTA circuit was constructed. A DC simulation was then performed on the constructed circuit to obtain the static operating point information of the input pair transistors N1 and N2 and the current mirror transistor N3 in the circuit, as well as their respective total dose transfer curves before irradiation. Step 2: Based on the BSIMSOI V4.2 model file in the 130nm PDSOI process library, extract the process parameters of the input transistors N1 and N2 and the current mirror transistor N3. Then, use the SDE tool in Sentaurus TCAD simulation software to create 3D models of the input transistors N1 and N2 and the current mirror transistor N3. Step 3: Using the Sdevice tool in Sentaurus TCAD simulation software, calibrate the 3D model obtained in Step 2 and add the Radiation irradiation model. Then, perform a total dose irradiation simulation to obtain the total dose transfer curves after irradiation for the input pair tubes N1 and N2 and the current mirror tube N3. Step 4: Adjust the parameters of the input transistor pair N1 and N2 and the current mirror N3 in the BSIMSOI V4.2 model file, and perform a total dose irradiation simulation using the Spectre simulator in the Cadence EDA tool to obtain the total dose irradiation transfer curves of the adjusted input transistor pair N1 and N2 and the current mirror N3. Then, perform curve fitting on the corresponding total dose irradiation transfer curves in steps 4 and 3. Step 5: Repeat step 4 until the curve fitting reaches convergence; In step 6, using the Spectre simulator in the Cadence EDA tool, two AC simulations are performed before and after the modified BSIMSOI V4.2 model file is imported into the five-transistor OTA circuit in step 1 to obtain the results of the total dose effect on the five-transistor OTA circuit.

[0006] In one embodiment of the present invention, in step 1, the process of obtaining the static operating point information of the input pair transistors N1 and N2 and the current mirror transistor N3 in the circuit includes: The constructed five-transistor OTA circuit was DC simulated using the Spectre simulator in the Cadence EDA tool to obtain the gate-source voltage Vgs1 and drain-source voltage Vds1 of the input pair transistors N1 and N2, as well as the gate-source voltage Vgs2 and drain-source voltage Vds2 of the current mirror transistor N3, as their respective static operating point information.

[0007] In one embodiment of the present invention, in step 1, the process of obtaining the total dose transfer curves before irradiation of the input pair tubes N1 and N2 and the current mirror tube N3 in the circuit includes: Based on the drain-source voltage Vds1 and the drain-source voltage Vds2, a DC simulation of the five-transistor OTA circuit was performed again using the Spectre simulator in the Cadence EDA tool to obtain transfer curves of the input pair transistors N1 and N2 when the drain-source voltage is the drain-source voltage Vds1 in the Cadence EDA tool, and a transfer curve of the current mirror transistor N3 when the drain-source voltage is the drain-source voltage Vds2 in the Cadence EDA tool.

[0008] In one embodiment of the present invention, in step 2, the process parameters of the transistors N1 and N2 and the current mirror transistor N3 are input, including: The input pair transistors N1 and N2 and the current mirror transistor N3 each have a width-to-length ratio, a top silicon film thickness, a gate oxide layer thickness, a buried oxide layer thickness, a source-drain length, a junction depth, a channel doping concentration, a substrate doping concentration, and a gate polysilicon doping concentration.

[0009] In one embodiment of the present invention, in step 3, the process of calibrating the 3D model obtained in step 2 includes: Step a1: Based on the drain-source voltage Vds1 and the drain-source voltage Vds2, a DC simulation is performed on the 3D model of the input pair tubes N1 and N2 and the 3D model of the current mirror tube N3 using the Sdevice tool in the Sentaurus TCAD simulation software to obtain the total dose transfer curves of the input pair tubes N1 and N2 and the current mirror tube N3 before irradiation; wherein the total dose transfer curves of the input pair tubes N1 and N2 before irradiation are the transfer curves of the input pair tubes N1 and N2 when the drain-source voltage is the drain-source voltage Vds1 in the Sentaurus TCAD simulation software, and the total dose transfer curve of the current mirror tube N3 before irradiation is the transfer curve of the current mirror tube N3 when the drain-source voltage is the drain-source voltage Vds2 in the Sentaurus TCAD simulation software; Step a2, performing curve fitting on the total dose transfer curve before irradiation obtained in step a1 and the total dose transfer curve before irradiation in step 1, and calculating the corresponding curve fitting error; Step a3, adjusting the 3D models of the input pair tubes N1 and N2 and the 3D model of the current mirror tube N3 according to the curve fitting error obtained in step a2; Step a4, returning to step a1, until the curve fitting error between the total dose transfer curve before irradiation obtained in step a1 and the total dose transfer curve before irradiation in step 1 is lower than the set value, indicating that the fitting converges and the calibration is successful.

[0010] In one embodiment of the present invention, in step 3, the process of adding the Radiation irradiation model includes: The gate-source voltage of the 3D model of the calibrated input pair tubes N1 and N2 is set to the gate-source voltage Vgs1, and the drain-source voltage is set to the drain-source voltage Vds1; the gate-source voltage of the 3D model of the calibrated current mirror tube N3 is set to the gate-source voltage Vgs2, and the drain-source voltage is set to the drain-source voltage Vds2; The materials of the buried oxide layer and isolation layer in the 3D models of the input pair tubes N1 and N2 with voltage setting completed, as well as the 3D model of the current mirror tube N3 with voltage setting completed, are replaced from Oxide to OxideAsSemiconductor. Then, the Sdevice tool in the Sentaurus TCAD simulation software is used to add the Radiation irradiation model to the buried oxide layer and isolation layer of the two 3D models.

[0011] In one embodiment of the present invention, in step 4, the parameters of the input transistors N1 and N2 and the current mirror transistor N3 in the BSIMSOI V4.2 model file include: The input pair tubes N1 and N2, and the current mirror tube N3 each correspond to the threshold voltage initial value Vth0, the subthreshold slope related parameter Ivoff, the subthreshold slope related parameter Nfactor, the carrier mobility U0, the first-order mobility degradation coefficient Ua, the second-order mobility degradation coefficient Ub and the on-state current related parameter Vsat. Compared with the prior art, the present invention has the following beneficial effects: Based on Sentaurus TCAD simulation software, Cadence EDA tools, and the BSIMSOI V4.2 model file provided by the 130nm PDSOI device process library, the present invention simulates the degradation effect of the total dose effect on the five-transistor OTA (OTA) basic module of the analog circuit by adding a radiation irradiation model, adjusting the 3D models of the input pair tube and current mirror tube in the five-transistor OTA circuit, and adjusting the BSIMSOI V4.2 model file parameters. This method can significantly reduce the cost of tape-out and irradiation experiments, and at the same time solve the problems of long simulation time and difficulty in convergence in total dose circuit-level irradiation simulation in semiconductor process and device simulation software TCAD.

[0012] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 1 is a flow chart of a five-tube OTA total dose effect modeling and simulation method provided by an embodiment of the present invention; Figure 2 1 is a schematic structural diagram of a five-transistor OTA circuit provided by an embodiment of the present invention; Figure 3 The embodiment of the present invention provides a structure and cross-sectional schematic diagram of a 3D model of any one of the input pipes; Figure 4 This is a schematic diagram of the structure and cross-section of a 3D model of a current mirror tube provided by an embodiment of the present invention; Figure 5 Schematic diagram comparing transfer curves of the input pair tubes provided in an embodiment of the present invention before and after total dose irradiation in Sentaurus TCAD simulation software and Cadence EDA tool; Figure 6 Schematic diagram comparing transfer curves of the current mirror tube provided by an embodiment of the present invention before and after total dose irradiation in Sentaurus TCAD simulation software and Cadence EDA tool; Figure 7 3. It is a schematic diagram comparing the five-tube OTA AC simulation results before and after total dose irradiation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0014] The present invention will be further described in detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

[0015] An embodiment of the present invention provides a five-tube OTA total dose effect modeling and simulation method.

[0016] See Figure 1 , Figure 1 It is a flow chart of a five-tube OTA total dose effect modeling and simulation method provided by an embodiment of the present invention.

[0017] The above-mentioned five-tube OTA total dose effect modeling and simulation method includes: Step 1: Based on the 130nm PDSOI process library and Cadence EDA tools, a five-transistor OTA circuit was constructed. A DC simulation was then performed on the constructed circuit to obtain the static operating point information of the input pair transistors N1 and N2 and the current mirror transistor N3 in the circuit, as well as their respective total dose transfer curves before irradiation. For the above five-tube OTA circuit structure, please refer to Figure 2 , Figure 2This is a schematic diagram of the structure of a five-transistor OTA circuit provided by an embodiment of the present invention. The red circled area indicates the area sensitive to total dose effects, including the input transistor pair N1 and N2 and the current mirror transistor N3. These input transistors N1 and N2, as well as the current mirror transistor N3, all use NMOS devices from the 130nm PDSOI process library. N1 and N2 in the input transistor pair use the same NMOS device, meaning they have identical parameters. Furthermore, the 130nm PDSOI process library is a device process library, a collection of devices provided by chip manufacturers, including field-effect transistors (MOSFETs), PN junctions, BJTs, resistors, capacitors, and other components. 130nm represents the technology node of this process library, but it can also represent other values, such as 55nm or 28nm process libraries. This example uses the 130nm process library. In the Cadence EDA tool, you need to call the devices in the process library to build the circuit and perform circuit simulation. Since the five-transistor OTA circuit is a very classic circuit in this field and is well known to those skilled in the art, the circuit construction process will not be described in detail here.

[0018] In step 1, the process of obtaining the static operating point information of the input pair transistors N1 and N2 and the current mirror transistor N3 in the constructed five-transistor OTA circuit includes: Using the Spectre simulator in the Cadence EDA tool, a DC simulation of the built five-transistor OTA circuit was performed to obtain the gate-source voltage Vgs1 and drain-source voltage Vds1 of the above-mentioned transistors N1 and N2, as well as the gate-source voltage Vgs2 and drain-source voltage Vds2 of the above-mentioned N3, as their respective static operating point information. Specific values ​​are shown in Table 1: Table 1 Information on the static operating points of the input pair transistors N1 and N2 and the current mirror transistor N3

[0019] Specifically, in step 1, the process of obtaining the total dose transfer curves before irradiation of the input pair tubes N1 and N2 and the current mirror tube N3 in the above circuit includes: Based on the drain-source voltages Vds1 and Vds2, a DC simulation of the five-transistor OTA circuit was performed again using the Spectre simulator in the Cadence EDA tool. This yielded the transfer curves for the input pair transistors N1 and N2 when the drain-source voltage was Vds1, as well as the transfer curve for the current mirror transistor N3 when the drain-source voltage was Vds2. These two transfer curves were saved, labeled Spectre1_pre and Spectre2_pre, for subsequent calibration of the 3D model in the Sentaurus TCAD simulation software.

[0020] Step 2: Based on the BSIMSOI V4.2 model file in the 130nm PDSOI process library, extract the process parameters of the input transistors N1 and N2 and the current mirror transistor N3. Then, use the SDE tool in Sentaurus TCAD simulation software to create 3D models of the input transistors N1 and N2 and the current mirror transistor N3. Specifically, the BSIMSOI V4.2 model file is a code-level file of the 130nm PDSOI process library, and includes various information about the devices in the process library.

[0021] Specifically, in step 2, the process parameters of the transistors N1 and N2 and the current mirror transistor N3 are input, including: The width-to-length ratio, top silicon film thickness, gate oxide thickness, buried oxide thickness, source-drain length, junction depth, channel doping concentration, substrate doping concentration, and gate polysilicon doping concentration of the input transistors N1 and N2, and the current mirror transistor N3. Specific values ​​are shown in Table 2: Table 2 Process parameters of input pair tubes N1 and N2 and current mirror tube N3

[0022] Specifically, the sde tool in the Sentaurus TCAD simulation software is used to construct the 3D model of the input tubes N1 and N2 according to the process parameters of the input tubes N1 and N2 in Table 2, and select a reasonable grid density, as shown in Figure 3 Among them, a reasonable grid density can be obtained based on the simulation experience of those skilled in the art, and ultimately the result of the simulation 3D model can be accurate and the simulation can converge. Figure 3 This is a schematic diagram of the structure and cross-section of a 3D model of any one of the input pair tubes provided by an embodiment of the present invention. Since N1 and N2 in the input pair tubes have exactly the same parameters, the same 3D model is used in 3D modeling. Therefore, for simplicity, Figure 3 Only one of them is shown. Figure 3 The 3D structure diagram on the left shows that the input pair N1 and N2 are PDSOI NMOS with an "H" gate structure. Figure 3 The cross-sectional view on the right shows that the device structure of the input pair N1 and N2 includes: gate oxide layer and sidewalls on both sides of the gate oxide layer, channel, source terminal, drain terminal, STI sidewalls on both sides of the source and drain, BOX buried oxide layer and substrate. In addition, Figure 3 The bar legend in the lower right corner of the figure shows the doping concentration of the corresponding color area in the input transistor N1 and N2 structures.

[0023] Specifically, the 3D modeling process of tubes N1 and N2 is analogously input to construct the 3D model of the current mirror tube N3, as shown in Figure 4 shown. Figure 4 This is a schematic diagram of the structure and cross-section of a 3D model of a current mirror tube provided by an embodiment of the present invention. Figure 4 The three-dimensional structure diagram on the left shows that the current mirror tube N3 is a PDSOI NMOS with an "H" gate structure; Figure 4 The cross-sectional view on the right shows that the current mirror tube N3 device structure includes: gate oxide layer and sidewalls on both sides of the gate oxide layer, channel, source terminal, drain terminal, STI sidewalls on both sides of the source and drain, BOX buried oxide layer and substrate. In addition, Figure 4 The bar graph in the lower right corner shows the doping concentration of the corresponding colored area in the current mirror tube N3 structure.

[0024] Step 3: Use the Sdevice tool in Sentaurus TCAD simulation software to calibrate the 3D model obtained in Step 2 and add the Radiation irradiation model. Then perform a total dose irradiation simulation to obtain the total dose transfer curves after irradiation for the input pair tubes N1 and N2 and the current mirror tube N3. Specifically, in step 3, the process of calibrating the 3D model obtained in step 2 includes: Step a1: Based on the above-mentioned drain-source voltage Vds1 and drain-source voltage Vds2, a DC simulation is performed on the 3D model of the input pair tubes N1 and N2 and the 3D model of the current mirror tube N3 using the Sdevice tool in the Sentaurus TCAD simulation software to obtain the total dose transfer curves of the input pair tubes N1 and N2 and the current mirror tube N3 before irradiation; wherein the total dose transfer curves of the input pair tubes N1 and N2 before irradiation are the transfer curves of the input pair tubes N1 and N2 when the drain-source voltage is the drain-source voltage Vds1 in the Sentaurus TCAD simulation software, and the total dose transfer curve of the current mirror tube N3 before irradiation is the transfer curve of the current mirror tube N3 when the drain-source voltage is the drain-source voltage Vds2 in the Sentaurus TCAD simulation software; Specifically, using the Sdevice tool in the Sentaurus TCAD simulation software, the statements "Grid = "input pair 3D model file name.tdr" and "Doping = "input pair 3D model file name.tdr"" are used to instruct the Sdevice tool to load the boundary file and grid file information for the 3D models of the input pair N1 and N2. "Input pair 3D model file name" is the file name corresponding to the 3D model file for the input pair N1 and N2 obtained in step 2. Subsequently, a physical calculation model is set, and the drain-source voltage values ​​of the 3D models of the input pair N1 and N3 are set to the values ​​corresponding to Vds1 in Table 1. The gate-source voltage is swept from 0 to 1.2 V to obtain the total dose transfer curves of the input pair N1 and N2 in the Sentaurus TCAD simulation software before irradiation, which is recorded as TCAD1_pre. The above physical calculation model is the one provided with the Sentaurus TCAD simulation software. Generally, the default model is sufficient, but it can also be fine-tuned based on the simulation experience of those skilled in the art.

[0025] For the current mirror tube N3, by analogy with the above operation, the total dose transfer curve before irradiation of the current mirror tube N3 in the Sentaurus TCAD simulation software can be obtained, which is recorded as TCAD2_pre.

[0026] Step a2, performing curve fitting on the total dose transfer curve before irradiation obtained in step a1 and the total dose transfer curve before irradiation in step 1, and calculating the corresponding curve fitting error; Step a3, adjusting the 3D models of the input pair tubes N1 and N2 and the 3D model of the current mirror tube N3 according to the curve fitting error obtained in step a2; Step a4, returning to step a1, until the curve fitting error between the total dose transfer curve before irradiation obtained in step a1 and the total dose transfer curve before irradiation in step 1 is lower than the set value, indicating that the fitting converges and the calibration is successful.

[0027] For the pre-irradiation total dose transfer curve fitting process for input pairs of tubes N1 and N2, the following steps are performed: The curve TCAD1_pre obtained in step a1 is compared with the curve Spectre1_pre obtained in step 1. Using the curve Spectre1_pre as a standard, the 3D model is adjusted by fitting, calculating the fitting error, and finally adjusting the 3D model to gradually approximate the curve TCAD1_pre to the standard. Ultimately, the curve fitting error between the curves TCAD1_pre and Spectre1_pre falls below the set value, indicating convergence and successful calibration. The curve fitting error is the mean square error, and the set value is 5%. Furthermore, adjusting the 3D model is a common procedure performed by those skilled in the art when calibrating 3D models in Sentaurus TCAD simulation software and will not be elaborated upon here.

[0028] For the fitting results of the total dose transfer curves before irradiation for tubes N1 and N2, see Figure 5 . Figure 5 1 is a schematic diagram comparing transfer curves of the input pair tubes provided in an embodiment of the present invention before and after total dose irradiation in Sentaurus TCAD simulation software and Cadence EDA tool. Figure 5 The black solid line in the middle is the transfer curve TCAD1_pre, and the black triangular scattered curve is Spectre1_pre. The two have a small difference only in the off-state leakage region. Since the static operating point of the device in the circuit is not in the off-state leakage region, the impact of this difference can be ignored.

[0029] The fitting process of the total dose transfer curve before irradiation of the current mirror tube N3 is similar to the processing of the above input tubes N1 and N2, and finally the fitting of the curve TCAD2_pre and the curve Spectre2_pre converge.

[0030] For the fitting results of the total dose transfer curve before irradiation of the current mirror tube N3, see Figure 6 . Figure 6 Schematic diagram comparing transfer curves of the current mirror tube provided by an embodiment of the present invention before and after total dose irradiation in Sentaurus TCAD simulation software and Cadence EDA tool. Figure 6 The black solid line in the middle is the transfer curve TCAD2_pre, and the black triangular scatter curve is Spectre2_pre. The fit of the two meets the same calibration requirements.

[0031] Specifically, in step 3, the process of adding the Radiation model includes: The gate-source voltage of the 3D model of the calibrated input pair tubes N1 and N2 is set to the gate-source voltage Vgs1, and the drain-source voltage is set to the drain-source voltage Vds1; the gate-source voltage of the 3D model of the calibrated current mirror tube N3 is set to the gate-source voltage Vgs2, and the drain-source voltage is set to the drain-source voltage Vds2; It should be noted that since the total dose effect is very sensitive to the distribution of the internal electric field of the device, in order to make the simulation data more accurate, the input pair tubes and the current mirror tube need to be biased at their respective static operating points before irradiation, that is, the gate-source voltage of the input pair tubes N1 and N2 is equal to the corresponding value of Vgs1, and the drain-source voltage is equal to the corresponding value of Vds1; the gate-source voltage of the current mirror tube N3 is equal to the corresponding value of Vgs2, and the drain-source voltage is the corresponding value of Vds2.

[0032] The materials of the buried oxide layer and isolation layer in the 3D models of the input pair tubes N1 and N2 with voltage setting completed, as well as the 3D model of the current mirror tube N3 with voltage setting completed, are replaced from Oxide to OxideAsSemiconductor. Then, the Sdevice tool in the Sentaurus TCAD simulation software is used to add the Radiation irradiation model to the buried oxide layer and isolation layer of the above two 3D models.

[0033] The purpose of replacing the materials of the buried oxide layer and the isolation layer is to enable the above-mentioned 3D model to be used for total dose irradiation simulation. The above-mentioned Radiation irradiation model is a model that comes with the Sentaurus TCAD simulation software. Since the BSIMSOI V4.2 model file only contains the parameter values ​​of the device and the irradiation model cannot be directly added, and the Spectre simulator in the Cadence EDA tool also does not have the function of irradiation simulation, the extent of the impact of irradiation on the device needs to be determined by performing irradiation simulation experiments in the Sentaurus TCAD simulation software. In addition, the present invention can effectively solve the problem of long irradiation simulation time directly in the Sentaurus TCAD simulation software by alternating the use of the Cadence EDA tool and Sentaurus TCAD.

[0034] Then, using the Radiation(DoseRate=“dose rate”, DoseTime=“total irradiation time”) statement in the Sdevice tool in Sentaurus TCAD simulation software, the dose rate was set to 100 rad(Si) / s, and the total irradiation time was taken at time points of 500s, 1000s, 2000s, and 3000s, corresponding to total irradiation doses of 50krad(Si), 100krad(Si), 200krad(Si), and 300krad(Si), respectively. Irradiation simulation experiments were performed on the 3D models of the input pair tubes N1 and N2 and the 3D model of the current mirror tube N3. rad(Si) is rad silicon, which represents the energy absorbed by radiation per unit mass of Si.

[0035] The two 3D models were then saved in their irradiated states using the Set(Traps (Frozen)) statement in the Sdevice tool within the Sentaurus TCAD simulation software to prevent annealing. The gate-source voltage of the two 3D models was then swept from 0V to 1.2V to generate transfer curves for total doses of 50 krad(Si), 100 krad(Si), 200 krad(Si), and 300 krad(Si). The post-irradiation transfer curves for input transistors N1 and N2 were designated TCAD1_50k, TCAD1_100k, TCAD1_200k, and TCAD1_300k, respectively; the post-irradiation transfer curves for current mirror transistor N3 were designated TCAD2_50k, TCAD2_100k, TCAD2_200k, and TCAD2_300k.

[0036] Step 4: Adjust the parameters of the input transistor pair N1 and N2 and the current mirror N3 in the BSIMSOI V4.2 model file, and perform a total dose irradiation simulation using the Spectre simulator in the Cadence EDA tool to obtain the total dose irradiation transfer curves of the adjusted input transistor pair N1 and N2 and the current mirror N3. Then, perform curve fitting on the corresponding total dose irradiation transfer curves in steps 4 and 3. Specifically, in step 4, the parameters of the input transistors N1 and N2 and the current mirror transistor N3 in the BSIMSOI V4.2 model file include: The input transistors N1 and N2, and the current mirror transistor N3 each correspond to the threshold voltage initial value Vth0, the subthreshold slope related parameter Ivoff, the subthreshold slope related parameter Nfactor, the carrier mobility U0, the first-order mobility degradation coefficient Ua, the second-order mobility degradation coefficient Ub and the on-state current related parameter Vsat.

[0037] Next, the parameters of the corresponding devices in the BSIMSOI V4.2 model file were initially adjusted. Again, adjusting these parameters is well known to those skilled in the art and will not be detailed here. The total-dose irradiation transfer curves for the input pairs N1 and N2 were then obtained using the Spectre simulator in the Cadence EDA tool. These curves were then initially fitted to the total-dose irradiation transfer curves for TCAD1_50k, TCAD1_100k, TCAD1_200k, and TCAD1_300k obtained in step 3, and the corresponding curve-fitting errors were calculated. Similarly, the total dose transfer curves for current mirror tube N3 obtained in the Cadence EDA tool, denoted as Spectre2_50k, Spectre2_100k, Spectre2_200k, and Spectre2_300k, are initially curve-fitted with the total dose transfer curves for TCAD2_50k, TCAD2_100k, TCAD2_200k, and TCAD2_300k obtained in step 3. The corresponding curve-fitting errors are calculated. The curve-fitting errors are the mean squared errors between the corresponding curves.

[0038] Step 5: Repeat step 4 until the curve fitting reaches convergence; Here, the total dose transfer curve obtained in Sentaurus TCAD simulation software is used as the standard. Adjustments are made to gradually bring the total dose transfer curve obtained in Cadence EDA closer to the standard. Ultimately, the curve fitting of the two sets of transfer curves converges, meaning that the corresponding curve fitting error falls below the set value. Similarly, the handling of the curve fitting error here is the same as described in Step 3.

[0039] For the fitting results of the total dose transfer curve after irradiation of tubes N1 and N2, see Figure 5 .like Figure 5 As shown, the red triangle scatter curve Spectre1_50k, the blue triangle scatter curve Spectre1_100k, the green triangle scatter curve Spectre1_200k and the purple triangle scatter curve Spectre1_300k correspond to the total dose points of 50krad(Si), 100krad(Si), 200krad(Si) and 300krad(Si), respectively, and are compared with Figure 5The red solid line TCAD1_50k, blue solid line TCAD1_100k, green solid line TCAD1_200k, and purple solid line TCAD1_300k are highly fitted, which can well represent the state of the input transistor after irradiation. They can also be further applied to circuit-level five-transistor OTA simulation through the Spectre simulator in the Cadence EDA tool.

[0040] For the fitting results of the transfer curve after total dose irradiation of current mirror tube N3, see Figure 6 .like Figure 6 As shown, the red triangle scatter curve Spectre2_50k, the blue triangle scatter curve Spectre2_100k, the green triangle scatter curve Spectre2_200k and the purple triangle scatter curve Spectre2_300k correspond to the total dose points of 50krad(Si), 100krad(Si), 200krad(Si) and 300krad(Si), respectively, and are compared with Figure 6 The red solid line TCAD2_50k, blue solid line TCAD2_100k, green solid line TCAD2_200k, and purple solid line TCAD2_300k are highly fitted, which can well represent the state of the current mirror tube after irradiation. They can also be further applied to circuit-level five-tube OTA simulation through the Spectre simulator in the Cadence EDA tool.

[0041] In step 6, using the Spectre simulator in the Cadence EDA tool, two AC simulations are performed before and after the modified BSIMSOI V4.2 model file is imported into the five-transistor OTA circuit in step 1 to obtain the results of the total dose effect on the five-transistor OTA circuit.

[0042] Specifically, the Spectre simulator within the Cadence EDA tool performs an AC simulation on the five-transistor OTA circuit initially constructed in Step 1 to obtain its initial low-frequency gain. Next, the Spectre simulator opens the rule-based model library within the ADE tool and imports the corresponding BSIMSOI V4.2 model file, modified in Step 4, to replace the original BSIMSOI V4.2 model file. A second AC simulation is then performed on the five-transistor OTA circuit to simulate the degradation of its initial low-frequency gain due to the total dose effect.

[0043] The results of the above two AC simulations can be found in Figure 7 , Figure 7 The embodiment of the present invention provides a schematic diagram comparing the five-tube OTA AC simulation results before and after total dose irradiation. Figure 7As shown in the figure, the initial low-frequency gain of the original five-transistor OTA is 39.661dB. After irradiation with a total dose of 50krad(Si), 100krad(Si), 200krad(Si), and 300krad(Si), the low-frequency gain of the five-transistor OTA decreases to 39.353dB, 36.936dB, 31.283dB, and 18.71dB, respectively. It can be seen that when the total dose is less than 100krad(Si), the gain degradation is less than 6.8%, and the circuit can still be used normally. When the total dose reaches 300krad(Si), the gain degradation reaches 52.78%, which will have a serious impact on circuit performance and cause the failure of this module and even subsequent modules.

[0044] Based on Sentaurus TCAD simulation software, Cadence EDA tools, and the BSIMSOI V4.2 model file provided by the 130nm PDSOI device process library, the present invention simulates the degradation effect of the total dose effect on the five-transistor OTA (OTA) basic module of the analog circuit by adding a radiation irradiation model, adjusting the 3D models of the input pair tube and current mirror tube in the five-transistor OTA circuit, and adjusting the BSIMSOI V4.2 model file parameters. This method can significantly reduce the cost of tape-out and irradiation experiments, and at the same time solve the problems of long simulation time and difficulty in convergence in total dose circuit-level irradiation simulation in semiconductor process and device simulation software TCAD.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A five-tube OTA total dose effect modeling and simulation method, characterized in that: include: Step 1: Based on the 130nm PDSOI process library and Cadence EDA tools, a five-transistor OTA circuit was constructed. A DC simulation was then performed on the constructed circuit to obtain the static operating point information of the input pair transistors N1 and N2 and the current mirror transistor N3 in the circuit, as well as their respective total dose transfer curves before irradiation. Step 2: Based on the BSIMSOI V4.2 model file in the 130nm PDSOI process library, extract the process parameters of the input transistors N1 and N2 and the current mirror transistor N3. Then, use the SDE tool in Sentaurus TCAD simulation software to create 3D models of the input transistors N1 and N2 and the current mirror transistor N3. Step 3: Using the Sdevice tool in Sentaurus TCAD simulation software, calibrate the 3D model obtained in Step 2 and add the Radiation irradiation model. Then, perform a total dose irradiation simulation to obtain the total dose transfer curves after irradiation for the input pair tubes N1 and N2 and the current mirror tube N3. Step 4: Adjust the parameters of the input transistor pair N1 and N2 and the current mirror N3 in the BSIMSOI V4.2 model file, and perform a total dose irradiation simulation using the Spectre simulator in the Cadence EDA tool to obtain the total dose irradiation transfer curves of the adjusted input transistor pair N1 and N2 and the current mirror N3. Then, perform curve fitting on the corresponding total dose irradiation transfer curves in steps 4 and 3. Step 5: Repeat step 4 until the curve fitting reaches convergence; In step 6, using the Spectre simulator in the Cadence EDA tool, two AC simulations are performed before and after the modified BSIMSOI V4.2 model file is imported into the five-transistor OTA circuit in step 1 to obtain the results of the total dose effect on the five-transistor OTA circuit.

2. A five-tube OTA total dose effect modeling and simulation method according to claim 1, characterized in that: In step 1, the process of obtaining the static operating point information of the input pair transistors N1 and N2 and the current mirror transistor N3 in the circuit includes: The constructed five-transistor OTA circuit was DC simulated using the Spectre simulator in the Cadence EDA tool to obtain the gate-source voltage Vgs1 and drain-source voltage Vds1 of the input pair transistors N1 and N2, as well as the gate-source voltage Vgs2 and drain-source voltage Vds2 of the current mirror transistor N3, as their respective static operating point information.

3. The five-tube OTA total dose effect modeling and simulation method according to claim 2, characterized in that: In step 1, the process of obtaining the total dose transfer curves before irradiation of the input pair tubes N1 and N2 and the current mirror tube N3 in the circuit includes: Based on the drain-source voltage Vds1 and the drain-source voltage Vds2, a DC simulation of the five-transistor OTA circuit was performed again using the Spectre simulator in the Cadence EDA tool to obtain transfer curves of the input pair transistors N1 and N2 when the drain-source voltage is the drain-source voltage Vds1 in the Cadence EDA tool, and a transfer curve of the current mirror transistor N3 when the drain-source voltage is the drain-source voltage Vds2 in the Cadence EDA tool.

4. The five-tube OTA total dose effect modeling and simulation method according to claim 1, characterized in that: In step 2, the process parameters of the transistors N1 and N2 and the current mirror transistor N3 are input, including: The input pair transistors N1 and N2 and the current mirror transistor N3 each have a width-to-length ratio, a top silicon film thickness, a gate oxide layer thickness, a buried oxide layer thickness, a source-drain length, a junction depth, a channel doping concentration, a substrate doping concentration, and a gate polysilicon doping concentration.

5. The five-tube OTA total dose effect modeling and simulation method according to claim 2, characterized in that: In step 3, the process of calibrating the 3D model obtained in step 2 includes: Step a1: Based on the drain-source voltage Vds1 and the drain-source voltage Vds2, a DC simulation is performed on the 3D model of the input pair tubes N1 and N2 and the 3D model of the current mirror tube N3 using the Sdevice tool in the Sentaurus TCAD simulation software to obtain the total dose transfer curves of the input pair tubes N1 and N2 and the current mirror tube N3 before irradiation; wherein the total dose transfer curves of the input pair tubes N1 and N2 before irradiation are the transfer curves of the input pair tubes N1 and N2 when the drain-source voltage is the drain-source voltage Vds1 in the Sentaurus TCAD simulation software, and the total dose transfer curve of the current mirror tube N3 before irradiation is the transfer curve of the current mirror tube N3 when the drain-source voltage is the drain-source voltage Vds2 in the Sentaurus TCAD simulation software; Step a2, performing curve fitting on the total dose transfer curve before irradiation obtained in step a1 and the total dose transfer curve before irradiation in step 1, and calculating the corresponding curve fitting error; Step a3, adjusting the 3D models of the input pair tubes N1 and N2 and the 3D model of the current mirror tube N3 according to the curve fitting error obtained in step a2; Step a4, returning to step a1, until the curve fitting error between the total dose transfer curve before irradiation obtained in step a1 and the total dose transfer curve before irradiation in step 1 is lower than the set value, indicating that the fitting converges and the calibration is successful.

6. The five-tube OTA total dose effect modeling and simulation method according to claim 2, characterized in that: In step 3, the process of adding the Radiation model includes: The gate-source voltage of the 3D model of the calibrated input pair tubes N1 and N2 is set to the gate-source voltage Vgs1, and the drain-source voltage is set to the drain-source voltage Vds1; the gate-source voltage of the 3D model of the calibrated current mirror tube N3 is set to the gate-source voltage Vgs2, and the drain-source voltage is set to the drain-source voltage Vds2; The materials of the buried oxide layer and isolation layer in the 3D models of the input pair tubes N1 and N2 with voltage setting completed, as well as the 3D model of the current mirror tube N3 with voltage setting completed, are replaced from Oxide to OxideAsSemiconductor. Then, the Sdevice tool in the Sentaurus TCAD simulation software is used to add the Radiation irradiation model to the buried oxide layer and isolation layer of the two 3D models.

7. The five-tube OTA total dose effect modeling and simulation method according to claim 1, characterized in that: In step 4, the parameters of the input transistors N1 and N2 and the current mirror transistor N3 in the BSIMSOI V4.2 model file include: The input pair tubes N1 and N2, and the current mirror tube N3 each correspond to the threshold voltage initial value Vth0, the subthreshold slope related parameter Ivoff, the subthreshold slope related parameter Nfactor, the carrier mobility U0, the first-order mobility degradation coefficient Ua, the second-order mobility degradation coefficient Ub and the on-state current related parameter Vsat.

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