A Single-Particle Flip Section Simulation Method Based on TCAD-SPICE-Geant4 Co-simulation

Abstract

This invention discloses a single-event upset (SET) cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation, belonging to the field of integrated circuit radiation effects and hardening technology. First, the critical charge value inducing SET upset in integrated circuits is extracted using TCAD-SPICE co-simulation. Then, for single-transistor devices at sensitive circuit nodes, TCAD is used to simulate the transient current pulse curves at different locations of the device under single-event radiation, extracting the charge collection weights at different locations. Next, Geant4 is used to simulate the charge generated at different locations of the device under particle irradiation. Finally, the SET upset cross-section of the circuit is calculated. This simulation method has high reliability and can accurately predict the sensitivity of integrated circuits to single-event radiation, providing theoretical guidance for subsequent circuit-level radiation hardening design.

Description

Technical Field

[0001] This invention belongs to the field of integrated circuit radiation effects and hardening technology, and specifically relates to a single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation. Background Technology

[0002] Statistics released by the U.S. Nuclear and Space Radiation Effects Conference show that approximately 45% of spacecraft failures are attributed to radiation effects from electronic components, and among the various radiation effects of electronic components, single-event effects account for as much as 86%. This demonstrates that single-event effects are a major threat to the normal operation of integrated circuits in a radiation environment. Based on whether the circuit function of an integrated circuit can be recovered after experiencing a single-event event, circuit failures caused by single-event effects can be classified into soft errors and hard errors. Since the energy requirement for induced soft errors is lower than that for induced hard errors, single-event induced soft errors are considered the main cause of circuit failures. Among these, Single Event Upset (SEU), specifically referring to the circuit output flip caused by the deposition of energy at sensitive nodes of a single particle irradiating the circuit, generating charge, and being collected to form a transient current pulse, is a major source of soft errors in integrated circuits. Research on the SEU effect has become a focus in the field of integrated circuit radiation effects and radiation hardening technology.

[0003] The SEU cross section is an important parameter for measuring the single-particle sensitivity of a circuit. Traditional SEU cross section simulations typically employ the classic rectangular parallel-piped (RPP) model. This model simplifies the geometry of each layer of the integrated circuit into a cuboid from top to bottom by analyzing the cross-sectional layer sequence. A small cuboid within this cuboid is defined as the sensitive region. It is assumed that the charge generated by the energy deposited by radiated particles in this region will be collected, forming a transient current pulse that affects the circuit output. Specifically, when the amount of charge collected in the sensitive region exceeds a certain threshold, a SEU occurs at the circuit output. The ratio of the number of SEUs to the incident particle fluence is the SEU cross section. The limitations of this method are: First, using a cuboid to represent the sensitive region is overly simplistic and fails to accurately reflect the impact of device structure changes on the circuit's SEU. Second, in radiation-hardened integrated circuit design, adjusting the layout is a common SEU hardening technique, but the RPP model cannot accurately reflect the impact of layout changes on the circuit's SEU. Third, this method assumes that the charge generated by the energy deposited by radiating particles at different locations within the sensitive region will be collected with the same efficiency. However, in reality, due to the influence of the internal electric field of the device, the charge collection efficiency varies at different locations within the sensitive region. As the feature size of integrated circuits continues to shrink and the device integration density increases dramatically, the sensitive regions of adjacent devices overlap, causing the differences in charge collection efficiency at different locations within the sensitive region to become increasingly obvious, and significantly reducing the reliability of the RPP model.

[0004] Therefore, considering the actual device structure and combining it with the circuit layout, establishing a more accurate SEU cross-section simulation method for integrated circuits has important practical significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art. This invention provides a single-event flip section simulation method based on TCAD-SPICE-Geant4 co-simulation, which can accurately predict the sensitivity of integrated circuits to single-event radiation and provide theoretical guidance for subsequent circuit-level radiation hardening design.

[0006] To address the aforementioned technical problems, this invention provides a method for simulating single-event flip-off cross-sections based on TCAD-SPICE-Geant4 co-simulation, comprising:

[0007] Step 1: Based on the device's process parameters, construct the device model using TCAD software;

[0008] Step 2: Based on the device model constructed in Step 1, use TCAD simulation to obtain its transfer characteristic curve, compare it with the HSPICE simulation results, and perform model calibration by adjusting the model parameters.

[0009] Step 3: Set the gate center position of the device model calibrated in Step 2 as the single-particle incident point, change the linear energy transfer (LET) value of the incident particles, and use TCAD simulation to obtain the transient current pulse curves of the device under single-particle irradiation with different LET values.

[0010] Step 4: Build the integrated circuit, call the process library, and use HSPICE to simulate and verify the circuit function;

[0011] Step 5: Inject the single-particle transient current pulses corresponding to different LET values ​​obtained in step 3 into the sensitive nodes of the circuit in step 4, observe the changes in the output waveform, and determine the critical LET value that induces the output signal to generate SEU.

[0012] Step 6: Integrate the single-particle transient current pulse curve corresponding to the critical LET value in Step 5 to obtain the critical charge value of the inducing integrated circuit SEU;

[0013] Step 7: Set the LET value, change the single-particle incident position, use TCAD simulation to obtain the transient current pulse curves of the single-particle incident device at different positions, calculate the amount of charge collected at different positions, and extract the charge collection weights at different positions of the device.

[0014] Step 8: Based on the real device model and the circuit layout design, use Geant4 to build the circuit model;

[0015] Step 9: For the circuit model constructed in Step 8, divide the single-transistor device at the sensitive node into regions according to the single-particle incident position selected in Step 7, use Geant4 simulation to obtain the energy value deposited in different regions of the device under particle irradiation, and convert it into the amount of generated charge.

[0016] Step 10: Based on the critical charge value of the SEU of the induction circuit extracted in Step 6, the charge collection weight of different positions of the device extracted in Step 7, and the amount of generated charge at different positions of the device extracted in Step 9, the SEU cross section of the circuit is calculated.

[0017] Preferably, in step 1, the device model is constructed using Silvaco TCAD software.

[0018] Preferably, in step 2, based on the Cadence platform, the single-tube device model in the process library is called, and the HSPICE simulator is used to simulate the single-tube transfer characteristic curve.

[0019] Preferably, in step 3, the device is placed in an off-biased state, and a single particle is incident perpendicularly to the surface of the device.

[0020] Preferably, in step 4, Cadence is used to build the integrated circuit.

[0021] Preferably, in step 6, the single-particle transient current pulse curve describes the relationship between the drain current and time, i.e., I d (t). I d Integrating over time t yields the critical charge Q. crit As shown in equation (1):

[0022] Q crit =∫I d (t)dt(1)

[0023] Preferably, in step 7, the device is divided into n regions, and a single particle is incident from above the device along a direction perpendicular to the device surface, sequentially aimed at the center position of each region. TCAD simulation is used to obtain the transient current pulse curves of the single particle incident at different positions on the device. The charge value Q collected at different positions on the device is obtained by integrating the curves. i Let i represent the i-th region (i = 1, 2, ..., n). Therefore, the charge collection weight α at different locations of the device under single-particle irradiation... i It can be represented as:

[0024]

[0025] Where Q0 represents the charge value collected at the center of the gate of the single-particle incident device.

[0026] Preferably, in step 9, for sensitive nodes in the circuit, the device at the sensitive node is divided into n regions according to step 7, and the center of each region is the incident position of the radiating particles in step 7. Assuming that the charge collection weight remains unchanged in each region, Geant4 simulation is used to obtain the energy value of the radiating particles deposited in different regions of the device. Let E i Let Q represent the energy value (in eV) of particle irradiation deposition in the i-th region, then the amount of charge Q generated in that region. i (Unit: C) The expression is:

[0027]

[0028] Preferably, in step 10, the total charge Q collected at the sensitive node of the circuit under particle irradiation is... coll The expression is:

[0029]

[0030] Q coll The critical charge value Q of the induction circuit SEU crit Comparison, when Q coll ≥Qcrit When a SEU occurs in the circuit, the expression for the SEU cross-section of the circuit is:

[0031]

[0032] Where, N SEU The number of flips indicates the number of times the flips occurred, and F represents the incident particle flux.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. This invention constructs a device model based on the actual device structure and establishes a circuit model based on the actual layout, thereby making the simulation results more valuable for reference.

[0035] 2. Due to the influence of the internal electric field of the device, the charge collection efficiency at different locations of the device is not the same. This invention takes into account the charge collection weight at different locations of the device, so that the simulation results are closer to the actual test results.

[0036] 3. This invention is based on TCAD-SPICE-Geant4 co-simulation, which realizes the simulation of the SEU cross section of integrated circuits, laying the foundation for subsequent circuit-level radiation hardening design. Attached Figure Description

[0037] Figure 1 This is a flowchart of a single-particle flip-off section simulation method based on TCAD-SPICE-Geant4 co-simulation, as described in this invention.

[0038] Figure 2 This is a model diagram of an n-type bulk silicon fin field-effect transistor (FinFET) built using Silvaco TCAD.

[0039] Figure 3 This is a comparison chart of the transfer characteristic curves of the FinFET device obtained from TCAD and HSPICE simulations after model calibration.

[0040] Figure 4 The graph shows the single-particle transient current pulses generated in FinFET devices under single-particle irradiation with different LET values.

[0041] Figure 5 This is the schematic diagram of a NAND gate circuit.

[0042] Figure 6 The output voltage variation curves of the circuit caused by single-particle irradiation of sensitive node O with different LET values ​​are shown.

[0043] Figure 7 XZ plane diagram for dividing the region of n-type FinFET device.

[0044] Figure 8 This is a schematic diagram of a FinFET NAND gate circuit built using Geant4 based on the layout.

[0045] Figure 9 This is a comparison chart of the SEU cross section of the NAND gate circuit simulated using the method described in this invention and the experimental test results. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0047] like Figure 1 As shown, this embodiment of the invention provides a method for simulating single-particle flip-off cross-sections based on TCAD-SPICE-Geant4 co-simulation, including the following steps:

[0048] Step 1: Based on the device's process parameters, construct the device model using TCAD software.

[0049] Specifically, for FinFETs, referring to the process parameters in the standard industrial model BSIM-CMG, an n-type bulk silicon FinFET single-transistor model was constructed using Silvaco TCAD, such as... Figure 2 As shown.

[0050] Step 2: Based on the device model constructed in Step 1, use TCAD simulation to obtain its transfer characteristic curve, compare it with the HSPICE simulation results, and perform model calibration by adjusting the model parameters.

[0051] Specifically, based on the Cadence platform, the n-type FinFET model from the process library was called, and its transfer characteristic curve was simulated using the HSPICE simulator. Simulation settings for the transfer characteristic curve: drain voltage (V... d The voltage is set to 0.8V, the source is grounded to the substrate, and the gate voltage (V) is... g The voltage is increased from 0V to 1V in 0.1V steps, and the drain current (I) is extracted. d ) with gate voltage (V g The change curve of ) , i.e., the transfer characteristics (I d -V g )curve.

[0052] I obtained from TCAD simulation d -V gThe curves were compared with the HSPICE simulation results. Model calibration was performed by adjusting the source, drain, channel, and substrate doping concentrations. After model calibration, the I values ​​obtained from TCAD and HSPICE simulations were compared. d -V g Curve pairs, for example Figure 3 As shown.

[0053] Step 3: Set the gate center position of the device model calibrated in Step 2 as the single-particle incident point, change the linear energy transfer (LET) value of the incident particles, and use TCAD simulation to obtain the transient current pulse curves of the device under single-particle irradiation with different LET values.

[0054] Specifically, setting the device gate voltage V g =0V, drain voltage V d =0.8V, and simultaneously set a single particle perpendicular to the device surface for incidence, with the LET value of the incident particle selected as 1MeV·cm. 2 / mg, 1.5MeV·cm 2 / mg, 2MeV·cm 2 / mg, and 2.5MeV·cm 2 / mg, using TCAD simulation, the single-particle transient current pulse curve generated in the device under single-particle irradiation at the above LET value was obtained, as follows: Figure 4 As shown.

[0055] Step 4: Build the integrated circuit, call the process library, and use HSPICE to simulate and verify the circuit function.

[0056] Specifically, based on the Cadence platform, a NAND gate circuit is built, and the schematic diagram is as follows. Figure 5 As shown. The circuit function was verified using the HSPICE simulator.

[0057] Step 5: Inject the single-particle transient current pulses corresponding to different LET values ​​obtained in step 3 into the sensitive nodes of the circuit in step 4, observe the changes in the output waveform, and determine the critical LET value that induces the output signal to generate SEU.

[0058] Specifically, such as Figure 5The NAND gate circuit shown includes: input terminal A connected to the gates of p-type FinFET P1 and n-type FinFET N2, substrate of p-type FinFET P1 connected to the source, drain connected to the drains of p-type FinFET P2 and n-type FinFET N1, and output terminal O, substrate of p-type FinFET P2 connected to the source, gate connected to input terminal B and gate of n-type FinFET N1, source of n-type FinFET N1 connected to drain of n-type FinFET N2, and substrate connected to the substrate and source of n-type FinFET N2 and grounded. Figure 5 Point O in the diagram is the sensitive node of the circuit, corresponding to the output of the NAND gate. When both inputs A and B are low, the p-type FinFET is turned on, the n-type FinFET is turned off, and the output O is high. At this time, the substrate of the n-type FinFET is grounded, and the drain is connected to a high level, forming a reverse-biased pn junction between the drain and the substrate. A strong electric field is formed in the depletion region of the reverse-biased pn junction due to the presence of space charge. The charge generated by the energy deposited by radiated particles inside the n-type FinFET is collected by the drain under the influence of the electric field, forming a transient current pulse. When a single-particle transient current pulse acts on output O, the output potential is momentarily pulled low. As the LET value of the incident particles increases, the energy deposited inside the device by single-particle irradiation increases, generating more charge. The amount of charge collected by the drain increases accordingly, resulting in a larger peak value of the transient current pulse, leading to an even lower output potential that remains low for a longer period. When the LET value of the incident particle reaches the critical value, the potential of the output O flips from high level to low level and remains stably at low level. That is, the NAND gate circuit undergoes a SEU under single-particle irradiation.

[0059] The transient current pulses generated in the n-type FinFET device under single-event irradiation with different LET values ​​obtained from TCAD simulation in step 3 are injected into the sensitive node O. The change in the NAND gate output voltage is observed, and the critical LET value for inducing SEU in the output signal is determined to be 1.5 MeV·cm. 2 / mg, such as Figure 6 As shown.

[0060] Step 6: Integrate the single-particle transient current pulse curve corresponding to the critical LET value in Step 5 to obtain the critical charge value of the induced integrated circuit SEU.

[0061] Specifically, for Figure 4 LET = 1.5 MeV·cm 2 Integrating the single-particle transient pulse curve corresponding to / mg, the expression is:

[0062] Q crit =∫I d (t)dt(1)

[0063] Thus, the critical charge value Q of the induced NAND gate SEU is obtained. crit =1.0fC.

[0064] Step 7: Set the LET value, change the single-particle incident position, use TCAD simulation to obtain the transient current pulse curves of the single-particle incident device at different positions, calculate the amount of charge collected at different positions, and extract the charge collection weights at different positions of the device.

[0065] Specifically, six radiation particle sources, namely B, Ne, Ar, Cu, Kr, and Xe, were selected, and their corresponding LET values ​​are shown in Table 1.

[0066] Table 1

[0067]

[0068] Since incident particles primarily deposit energy and generate charge at the fins and substrate of the FinFET device, therefore... Figure 2 The Fin and substrate portions of the FinFET device model are based on Figure 7 The device is divided into 25 regions. A single particle is incident on the center of each region from above, perpendicular to the device surface. TCAD simulation is used to obtain the transient current pulse curves generated in the device at different incident positions. By integrating the curves, the charge value Q collected at different positions of the device is obtained. i Let i represent the i-th region (i = 1, 2, ..., 25). Therefore, the charge collection weight α at different locations of the device under single-particle irradiation... i It can be represented as:

[0069]

[0070] Where Q0 represents the charge value collected at the center of the gate of the single-particle incident device.

[0071] Step 8: Based on the real device model and the circuit layout design, use Geant4 to build the circuit model.

[0072] Specifically, based on the layout of the NAND gates, the Geant4-based silicon FinFET NAND gate circuit model is used, such as... Figure 8 As shown.

[0073] Step 9: Based on the circuit model constructed in Step 8, divide the single-transistor device at the sensitive node into regions according to the single-particle incident position selected in Step 7. Use Geant4 simulation to obtain the energy value deposited in different regions of the device under particle irradiation, and convert it into the amount of generated charge.

[0074] Specifically, the n-type FinFET device at the output terminal O of the NAND gate is divided into 25 regions according to step 7. The center of each region is the incident position of the radiated particles in step 7. Assuming that the charge collection weight remains unchanged in each region, Geant4 simulation is used to obtain the energy values ​​of the radiated particles deposited in different regions of the device. The radiated particle sources and corresponding energies are shown in Table 1. The energy values ​​of the radiated particles deposited in different regions of the device at the sensitive node obtained from the simulation are processed, and E is set to... i Let Q represent the energy value (in eV) of particle irradiation deposition in the i-th region, then the amount of charge Q generated in that region. i (Unit: C) The expression is:

[0075]

[0076] Step 10: Based on the critical charge value of the SEU of the induction circuit extracted in Step 6, the charge collection weight of different positions of the device extracted in Step 7, and the amount of generated charge at different positions of the device extracted in Step 9, the SEU cross section of the circuit is calculated.

[0077] Specifically, the total charge Q collected at the sensitive node of the circuit under particle irradiation coll The expression is:

[0078]

[0079] Q coll The critical charge value Q of the induction circuit SEU crit Comparison, when Q coll ≥Q crit When this occurs, a SEU occurs in the circuit. Therefore, the SEU cross-sectional expression for the circuit is:

[0080]

[0081] Where, N SEU The number of flips indicates the number of times the flips occurred, and F represents the incident particle flux.

[0082] Figure 9 This image shows a comparison between the SEU cross-section of FinFET and NOT gate circuits simulated using the method described in this invention and the experimental test results. It can be observed that as the LET value of the radiated particle increases, the calculated and experimental values ​​show a basically consistent trend, indicating that the single-event flip cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation proposed in this invention has high reliability and can accurately predict the sensitivity of integrated circuits to single-event radiation, providing theoretical guidance for subsequent circuit-level radiation hardening design.

[0083] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation, characterized in that, Includes the following steps: Step 1: Based on the device's process parameters, construct the device model using TCAD software; Step 2: Based on the device model constructed in Step 1, use TCAD simulation to obtain its transfer characteristic curve, compare it with the HSPICE simulation results, and perform model calibration by adjusting the model parameters. Step 3: Set the gate center position of the device model calibrated in Step 2 as the single-particle incident point, change the linear energy transfer (LET) value of the incident particle, and use TCAD simulation to obtain the transient current pulse curves of the device under single-particle irradiation with different LET values. Step 4: Build the integrated circuit, call the process library, and use HSPICE to simulate and verify the circuit function; Step 5: Inject the single-particle transient current pulses corresponding to different LET values ​​obtained in step 3 into the sensitive nodes of the circuit in step 4, observe the changes in the output waveform, and determine the critical LET value that induces the output signal to generate SEU. Step 6: Integrate the single-particle transient current pulse curve corresponding to the critical LET value in Step 5 to obtain the critical charge value of the inducing integrated circuit SEU; Step 7: Set the LET value, change the single-particle incident position, use TCAD simulation to obtain the transient current pulse curves of the single-particle incident device at different positions, calculate the amount of charge collected at different positions, and extract the charge collection weights at different positions of the device. Step 8: Based on the real device model and the circuit layout design, use Geant4 to build the circuit model; Step 9: For the circuit model constructed in Step 8, divide the single-transistor device at the sensitive node into regions according to the single-particle incident position selected in Step 7, use Geant4 simulation to obtain the energy value deposited in different regions of the device under particle irradiation, and convert it into the amount of generated charge. Step 10: Based on the critical charge value of the SEU of the induction circuit extracted in Step 6, the charge collection weight of different positions of the device extracted in Step 7, and the amount of generated charge at different positions of the device extracted in Step 9, the SEU cross section of the circuit is calculated.

2. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 1, characterized in that, In step 1, the device model is constructed using Silvaco TCAD software.

3. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 1, characterized in that, In step 2, based on the Cadence platform, the single-tube device model in the process library is called, and the HSPICE simulator is used to simulate the single-tube transfer characteristic curve.

4. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 1, characterized in that, In step 3, the device is placed in an off-biased state, and a single particle is incident perpendicularly onto the device surface.

5. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 1, characterized in that, In step 4, the Cadence platform is used to build the integrated circuit.

6. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 1, characterized in that, In step 6, the single-particle transient current pulse curve describes the relationship between the drain current and time, i.e., Id(t); integrating Id with respect to time t yields the critical charge Q. crit ,Right now: Q crit =∫I d (t)dt。 7. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 6, characterized in that, In step 7, the device is divided into n regions. A single particle is incident on the center of each region sequentially from above the device along a direction perpendicular to the device surface. TCAD simulation is used to obtain the transient current pulse curves of the single particle at different positions of the device. The charge value Q collected at different positions of the device is obtained by integrating the curves. i , where i represents the i-th region, i = 1, 2, ..., n; Therefore, the charge collection weight α at different locations of the device under single-particle irradiation... i Represented as: Where Q0 represents the charge value collected at the center of the gate of the single-particle incident device.

8. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 7, characterized in that, In step 9, for the sensitive nodes in the circuit, the device at the sensitive node is divided into n regions according to step 7, and the center of each region is the incident position of the radiating particles in step 7; assuming that the charge collection weight remains unchanged in each region, the energy value of the radiating particles deposited in different regions of the device is obtained using Geant4 simulation; let E i Let Q represent the energy value of particle irradiation deposition in the i-th region, then the amount of charge generated in that region is Q. i The expression is:

9. The single-particle flip-off cross-section simulation method based on TCAD-SPICE-Geant4 co-simulation as described in claim 8, characterized in that, In step 10, the total charge Q collected at the sensitive node of the circuit under particle irradiation is... coll The expression is: Q coll The critical charge value Q of the induction circuit SEU crit Comparison, when Q coll ≥Q crit When a SEU occurs in the circuit, the expression for the SEU cross-section of the circuit is: Where, N SEU The number of flips indicates the number of times the flips occurred, and F represents the incident particle flux.

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