A transistor interface state simulation method, computing device and storage medium
By constructing a Schottky-Reid-Hall composite model and continuity equations, the influence of transistor interface states is simulated, solving the problems of long time consumption and high cost of ground tests, and realizing efficient transistor interface state simulation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2022-11-10
- Publication Date
- 2026-04-24
AI Technical Summary
Ground-based experiments simulating the effects of space radiation on transistor interface states are time-consuming and costly.
A Schottky-Reid-Hall composite model was constructed and converted into the interface state trap concentration per unit area. Combined with the electron and hole continuity equations, a transistor interface state model was constructed and simulated using TCAD simulation software.
The simulation method simulates the effect of interface states on the base current of transistors under space radiation environment, saving costs and improving simulation efficiency.
Smart Images
Figure CN115659695B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of simulation technology for electronic devices, and more specifically, to a transistor interface state simulation method, computing device, and storage medium. Background Technology
[0002] Space radiation can cause ionization in bipolar devices. The ionization effect primarily damages the SiO2 passivation layer of the bipolar device and generates interface states at the SiO2 / Si interface, thus affecting the electrical performance parameters of the bipolar device. Ionizing radiation generates electron-hole pairs in the SiO2 layer. The generated electrons have high mobility, and most migrate out of the passivation layer. Before they migrate out, some electrons recombine with holes. Holes have slower mobility; besides those that recombine with electrons, the remaining holes are captured by defects in the SiO2 layer, forming trapped positive charges, which in turn introduce interface states at the SiO2 / Si interface.
[0003] The interface states at the SiO2 / Si interface lead to an increase in the surface recombination rate, resulting in an increase in base current, which in turn degrades the transistor current gain and causes radiation damage to bipolar devices.
[0004] To accurately evaluate the impact of interface states on transistors, ground-based irradiation tests are typically conducted to simulate the ground-space environment. However, ground-based tests are time-consuming and costly. Summary of the Invention
[0005] The problem solved by this invention is the high time consumption and cost of studying transistor interface states through ground-based experiments.
[0006] To address the above problems, this invention provides a transistor interface state simulation method, comprising:
[0007] A Schottky-Reid-Hall (SRH) complex model is constructed, wherein the Schottky-Reid-Hall complex model includes the concentration of the first interface trap per unit volume;
[0008] The concentration of the first interface trap is converted into the concentration of the second interface state trap per unit area, and a Schottky-Reid-Hall surface composite model is constructed based on the concentration of the second interface state trap.
[0009] Construct the electron continuity equation and the hole continuity equation;
[0010] The Schottky-Reid-Hall surface composite model is coupled with the electron continuity equation and the hole continuity equation to obtain the transistor interface state model.
[0011] The transistor interface state model was used to simulate the base current of the transistor under different concentrations of the second interface state trap.
[0012] The beneficial effects of this invention are as follows: By constructing a Schottky-Reed-Hall recombination model and converting the first interface trap concentration in the model into a second interface state trap concentration per unit area, a Schottky-Reed-Hall surface recombination model is constructed using the second interface trap concentration. The recombination rate derived from this model is then coupled into the continuity equation of electrons and holes in the transistor to obtain the transistor interface state model. Using this transistor interface state model to simulate the influence of interface states on the transistor base current in a space irradiation environment can save costs and better simulate the lower interface state base current in a space irradiation environment.
[0013] Optionally, constructing the Schottky-Reid-Hall composite model includes constructing the Schottky-Reid-Hall composite model according to a first formula, wherein the first formula includes:
[0014]
[0015] Among them, U S1 The recombination rate of the Schottky-Reid-Hall recombination model is given, where p is the hole concentration and n is the electron concentration. i E represents the intrinsic carrier concentration in silicon. t For the energy level of the defect trap, E i Let q be the intrinsic energy level in silicon, q be the elementary charge, k be the Boltzmann constant, T be the temperature, and τ be the eigenlevel. n For electron lifetime, τ p This refers to the hole's lifetime.
[0016] Optionally, the electronic lifetime is calculated using a second formula; wherein the second formula includes:
[0017]
[0018] Among them, v n For electron thermal velocity, σ n For the electron capture cross section, N t This represents the defect trap concentration.
[0019] Optionally, the hole lifetime is calculated using a third formula; wherein the third formula includes:
[0020]
[0021] Among them, v p Let σ be the hole thermal velocity. p For the hole trapping cross section, N t This represents the defect trap concentration.
[0022] Optionally, converting the first interface trap concentration into a second interface state trap concentration per unit area includes:
[0023] The first interface trap concentration is converted to the second interface state trap concentration using a fourth formula, wherein the fourth formula includes:
[0024]
[0025] Where, N st (cm -3 ) represents the concentration of the first interface state trap, N st (cm -2 ) represents the concentration of the second interface state trap, and 1e-7 is 1×10 -7 .
[0026] Optionally, constructing the Schottky-Reed-Hall surface composite model based on the second interface state trap concentration includes: substituting the second interface state trap concentration into the Schottky-Reed-Hall composite model to construct the Schottky-Reed-Hall surface composite model, wherein the Schottky-Reed-Hall surface composite model is represented by a fifth formula, the fifth formula including:
[0027]
[0028] Among them, U S2 p is the recombination rate of the Schottky-Reid-Hall surface recombination model, n is the hole concentration, and n is the electron concentration. i E represents the intrinsic carrier concentration in the silicon. t For the defect trap energy level, E i The intrinsic energy level in silicon is given by q, the elementary charge is given by q, the Boltzmann constant is given by k, and the temperature is given by v. n For electron thermal velocity, σ n For the electron capture cross section, v p Let σ be the hole thermal velocity. p For the hole trapping cross section, N st (cm -2 ) represents the concentration of the second interface state trap.
[0029] Optionally, the construction of the electron continuity equation and the hole continuity equation includes:
[0030] Obtain the electron current density and hole current density in the transistor;
[0031] Based on the electron current density, the electron continuity equation is constructed according to the sixth formula;
[0032] Based on the hole current density, the hole continuity equation is constructed according to the seventh formula;
[0033] The sixth formula includes:
[0034]
[0035] in, The electron current density, The electron concentration is the rate of change over time, and q is the elementary charge.
[0036] The seventh formula includes:
[0037]
[0038] in, The hole current density is... Let q be the rate of change of hole concentration over time, and q be the elementary charge.
[0039] Optionally, the step of coupling the Schottky-Reed-Hall surface recombination model with the electron continuity equation and the hole continuity equation respectively to obtain the transistor interface state model includes:
[0040] Using TCAD simulation software, the surface recombination rate is incorporated into the electron continuity equation and the hole continuity equation through formulas 8 and 9.
[0041] The eighth formula includes:
[0042]
[0043] in, The electron current density is... U is the rate of change of electron concentration over time, q is the elementary charge, and U is the electron concentration. S2 The composite rate of the Schottky-Reid-Hall surface composite model;
[0044] The ninth formula includes:
[0045]
[0046] in, The hole current density is... U is the rate of change of hole concentration over time, q is the elementary charge, and U is the number of holes. S2 The composite rate is the composite rate of the Schottky-Reid-Hall surface composite model.
[0047] The present invention also provides a computing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the transistor interface state simulation method as described in any of the preceding claims.
[0048] The computing device described in this invention has the same advantages over the prior art as the transistor interface state simulation method described above, and will not be repeated here.
[0049] The present invention also provides a computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the transistor interface state simulation method as described in any of the preceding claims.
[0050] The computer-readable storage medium described in this invention has the same advantages over the prior art as the transistor interface state simulation method described above, and will not be repeated here. Attached Figure Description
[0051] Figure 1 This is a flowchart of the transistor interface state simulation method in an embodiment of the present invention;
[0052] Figure 2 This is a schematic diagram of the transistor structure in an embodiment of the present invention;
[0053] Figure 3 This is a schematic diagram showing the base current variation of the transistor under different concentrations of interface states in an embodiment of the present invention. Detailed Implementation
[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0055] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein.
[0056] In the description of this specification, references to terms such as "embodiment," "some embodiments," and "optional embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or implementation is included in at least one embodiment or illustrative embodiment of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or implementations.
[0057] To evaluate the effects of space radiation on transistor devices, especially bipolar transistors, ground-based irradiation experiments are commonly used to simulate the space environment and study the effects on interface states. However, ground-based experiments are time-consuming and costly.
[0058] To this end, this invention provides a transistor interface state simulation method. By constructing a transistor interface state simulation model, the method simulates the changes in base current under different interface state trap concentrations, thereby simulating ground irradiation experiments.
[0059] Combination Figure 1 As shown, this embodiment of the invention provides a transistor interface state simulation method, including the following steps:
[0060] S1. Construct a Schottky-Reid-Hall composite model, wherein the Schottky-Reid-Hall composite model includes the concentration of the first interface trap per unit volume;
[0061] S2. Convert the first interface trap concentration into the second interface state trap concentration per unit area, and construct a Schottky-Reid-Hall surface composite model based on the second interface state trap concentration;
[0062] S3. Construct the electron continuity equation and the hole continuity equation;
[0063] S4. Couple the Schottky-Reid-Hall surface composite model with the electron continuity equation and the hole continuity equation respectively to obtain the transistor interface state model;
[0064] S5. The base current of the transistor under different second interface state trap concentrations is simulated using the transistor interface state model.
[0065] In this embodiment, a Schottky-Reed-Hall recombination model is constructed, and the first interface trap concentration in the model is converted into a second interface state trap concentration per unit area. Using this second interface trap concentration, a Schottky-Reed-Hall surface recombination model is constructed. The recombination rate derived from this model is then coupled into the continuity equation of electrons and holes in the transistor to obtain the transistor interface state model. Using this model, the influence of interface states on the transistor base current in a space irradiation environment can be simulated, saving costs and providing a better simulation of the lower interface state base current under space irradiation conditions.
[0066] In some embodiments, constructing the Schottky-Reid-Hall complex model in step S1 includes constructing the Schottky-Reid-Hall complex model according to a first formula, wherein the first formula includes:
[0067]
[0068] Among them, U S1 The recombination rate is given by the Schottky-Reid-Hall recombination model, where p is the hole concentration and n is the electron concentration. i E represents the intrinsic carrier concentration in silicon. t For the energy level of the defect trap, E i Let q be the intrinsic energy level in silicon, q be the elementary charge, k be the Boltzmann constant, T be the temperature, and τ be the eigenlevel. n For electron lifetime, τ p This refers to the hole's lifetime.
[0069] In some embodiments, the electronic lifetime is calculated by a second formula; wherein the second formula includes:
[0070]
[0071] Among them, v n For electron thermal velocity, σ n For the electron capture cross section, N t This represents the defect trap concentration.
[0072] The hole lifetime is calculated using a third formula; wherein the third formula includes:
[0073]
[0074] Among them, v p Let σ be the hole thermal velocity. p For the hole trapping cross section, N t The concentration of the defect trap is denoted as .
[0075] In some embodiments, in step S2, since interface state traps are mainly generated at the Si / SiO2 interface, they then act as recombination centers, leading to surface recombination at the Si / SiO2 interface. Surface recombination refers to the recombination process occurring at the semiconductor surface, where interface state traps also form recombination center energy levels within the bandgap. Therefore, in terms of recombination mechanisms, surface recombination is still indirect recombination. Thus, indirect recombination theory can be used to address surface recombination problems. Therefore, in this embodiment, the Schottky-Reed-Hall recombination model described above is used to calculate surface recombination.
[0076] In some embodiments, converting the first interface trap concentration to a second interface state trap concentration per unit area includes using a fourth formula to convert the first interface trap concentration to the second interface state trap concentration, wherein the fourth formula includes:
[0077]
[0078] Where, N st (cm-3 ) represents the concentration of the first interface state trap, N st (cm -2 ) represents the concentration of the second interface state trap, and 1e-7 is 1×10 -7 .
[0079] In this embodiment, the interface state trap is assumed to act at a thin layer at the interface, and the thickness of this thin layer is taken as 1 nm. Since the unit typically used when considering interface state concentration is cm... -2 In this embodiment, the unit area is taken as per square centimeter. The second interface state trap concentration per unit area is the second interface state trap concentration per square centimeter.
[0080] In this embodiment, by converting the first interface state trap concentration per unit volume into the second interface state trap concentration per unit area, and substituting the second interface state trap concentration into the Schottky-Reed-Hall composite model, a Schottky-Reed-Hall surface composite model is constructed.
[0081] In some embodiments, the Schottky-Reid-Hall surface composite model is represented by a fifth formula, which includes:
[0082]
[0083] Among them, U S2 The recombination rate is given by the Schottky-Reid-Hall surface recombination model, p is the hole concentration, and n is the electron concentration. i E represents the intrinsic carrier concentration in the silicon. t For the defect trap energy level, E i The intrinsic energy level in silicon is given by q, the elementary charge is given by q, the Boltzmann constant is given by k, and the temperature is given by v. n Let σ be the electron thermal velocity. n For the electron capture cross section, v p Let σ be the hole thermal velocity. p Let N be the hole-capturing cross section. st (cm -2 ) represents the concentration of the second interface state trap.
[0084] In some embodiments, step S3 includes: obtaining the electron current density and hole current density in the transistor; constructing the electron continuity equation according to the sixth formula based on the electron current density; and constructing the hole continuity equation according to the seventh formula based on the hole current density.
[0085] The sixth formula includes:
[0086]
[0087] in, The electron current density is... The electron concentration is the rate of change over time, and q is the elementary charge.
[0088] The seventh formula includes:
[0089]
[0090] in, The hole current density is... Let q be the rate of change of hole concentration over time, and q be the amount of elementary charge.
[0091] In some embodiments, in step S4, the Schottky-Reid-Hall surface recombination model is coupled with the electron continuity equation and the hole continuity equation to obtain a transistor interface state model, including: using TCAD simulation software, the surface recombination rate is added to the electron continuity equation and the hole continuity equation through the eighth and ninth formulas;
[0092] The eighth formula includes:
[0093]
[0094] in, The electron current density is... U is the rate of change of electron concentration over time, q is the elementary charge, and U is the electron concentration. S2 The composite rate of the Schottky-Reid-Hall surface composite model;
[0095] The ninth formula includes:
[0096]
[0097] in, The hole current density is... U is the rate of change of hole concentration over time, q is the elementary charge, and U is the number of holes. S2 The composite rate is the composite rate of the Schottky-Reid-Hall surface composite model.
[0098] In step S5, the base current of the transistor under different concentrations of interface states is simulated using the transistor interface state model. Combined with... Figure 2 As shown, Figure 2 The simulation model of an NPN bipolar transistor based on the actual device structure is shown. The emitter junction depth is 0.1 μm, the collector junction depth is 0.3 μm, and the emitter region is N-type doped with a concentration of 1e19 cm⁻¹. -3The base region is p-type doped with a concentration of 1e17cm. -3 The collector region is N-type doped with a doping concentration of 1e15cm. -3 The change in recombination rate caused by the interface state mainly occurs at the interface between Si and SiO2.
[0099] Combination Figure 3 As shown, the base current under different interface states is obtained by changing the concentration of the second interface state trap in the transistor. Figure 2 The NPN bipolar transistors are shown at 1e11cm. -2 ,5e11cm -2 1e12cm -2 The simulated base current I under the influence of the concentration of the interface state B The changes are as follows. It can be seen that with the increase of interface state concentration, the base current I in the high-voltage section... B There was no significant change, but the base current I in the low-voltage section... B The values all increase accordingly, exhibiting certain swing characteristics, consistent with the influence characteristics of interface state traps. This indicates that the interface state TCAD simulation method for bipolar transistors is reasonable.
[0100] This invention also provides a computing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the transistor interface state simulation method as described in any of the preceding embodiments.
[0101] The computing device described in this embodiment of the invention has the same advantages over the prior art as the transistor interface state simulation method described above, and will not be repeated here.
[0102] This invention also provides a computer-readable storage medium storing a computer program thereon, characterized in that, when the computer program is executed by a processor, it implements the transistor interface state simulation method as described in any of the preceding claims.
[0103] The computer-readable storage medium described in this embodiment of the invention has the same advantages over the prior art as the transistor interface state simulation method described above, and will not be repeated here.
[0104] While the above disclosure is provided, the scope of protection of this disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this disclosure.
Claims
1. A transistor interface state simulation method, characterized in that, include: A Schottky-Reid-Hall composite model is constructed, wherein the Schottky-Reid-Hall composite model includes the concentration of the first interface trap per unit volume; The concentration of the first interface trap is converted into the concentration of the second interface state trap per unit area, and a Schottky-Reid-Hall surface composite model is constructed based on the concentration of the second interface state trap. Construct the electron continuity equation and the hole continuity equation; The Schottky-Reid-Hall surface composite model is coupled with the electron continuity equation and the hole continuity equation to obtain the transistor interface state model. The transistor interface state model was used to simulate the base current of the transistor under different concentrations of the second interface state trap. The construction of the Schottky-Reid-Hall complex model includes: constructing the Schottky-Reid-Hall complex model according to a first formula, wherein the first formula includes: ； in, The recombination rate of the Schottky-Reid-Hall recombination model is given, where p is the hole concentration and n is the electron concentration. i E represents the intrinsic carrier concentration in silicon. t For the energy level of the defect trap, E i Let q be the intrinsic energy level in silicon, q be the elementary charge, k be the Boltzmann constant, and T be the temperature. For electronic lifetime, Hole lifetime; The step of converting the first interface trap concentration into a second interface state trap concentration per unit area includes: The first interface trap concentration is converted to the second interface state trap concentration using a fourth formula, wherein the fourth formula includes: ； in, The concentration of the first interface trap. The concentration of the second interface state trap. for ; The construction of the Schottky-Reid-Hall surface composite model based on the second interface state trap concentration includes: Substituting the concentration of the second interface state trap into the Schottky-Reid-Hall composite model, the Schottky-Reid-Hall surface composite model is constructed. The Schottky-Reid-Hall surface composite model is represented by a fifth formula, which includes: ； in, The recombination rate is given by the Schottky-Reid-Hall surface recombination model, p is the hole concentration, and n is the electron concentration. E represents the intrinsic carrier concentration in the silicon. t For the defect trap energy level, E i Here, q represents the intrinsic energy level in silicon, k represents the elementary charge, and T represents the temperature. For electron thermal velocity, For electron capture cross section, Hole heat velocity, For hole capture section, The concentration of the second interface state trap; The process of coupling the Schottky-Reid-Hall surface composite model with the electron continuity equation and the hole continuity equation respectively to obtain the transistor interface state model includes: Using TCAD simulation software, the recombination rate of the Schottky-Reid-Hall surface recombination model is incorporated into the electron continuity equation and the hole continuity equation through the eighth and ninth formulas; The eighth formula includes: ； in, For electron current density, U is the rate of change of the electron concentration over time. vol The equivalent volume recombination rate is given by δ, where δ is the thickness of the thin layer, and δ = 1 nm = 1 × 10⁻⁶. 7 cm, q is the elementary charge. The composite rate of the Schottky-Reid-Hall surface composite model; The ninth formula includes: ； in, Hole current density U is the rate of change of the hole concentration over time. vol The equivalent volume recombination rate is given by δ, where δ is the thickness of the thin layer, and δ = 1 nm = 1 × 10⁻⁶. 7 cm, q is the elementary charge. The composite rate is the composite rate of the Schottky-Reid-Hall surface composite model.
2. The transistor interface state simulation method according to claim 1, characterized in that, The electronic lifetime is calculated using a second formula; wherein the second formula includes: ； in, For electron thermal velocity, For electron capture cross section, This represents the defect trap concentration.
3. The transistor interface state simulation method according to claim 1, characterized in that, The hole lifetime is calculated using a third formula; wherein the third formula includes: ； in, Hole heat velocity, For hole capture section, This represents the defect trap concentration.
4. The transistor interface state simulation method according to claim 1, characterized in that, The construction of the electron continuity equation and the hole continuity equation includes: Obtain the electron current density and hole current density in the transistor; Based on the electron current density, the electron continuity equation is constructed according to the sixth formula; Based on the hole current density, the hole continuity equation is constructed according to the seventh formula; The sixth formula includes: ； in, The electron current density is... The electron concentration is the rate of change over time, and q is the elementary charge. The seventh formula includes: ； in, The hole current density is... Let q be the rate of change of hole concentration over time, and q be the elementary charge.
5. A computing device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the transistor interface state simulation method as described in any one of claims 1-4.
6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the transistor interface state simulation method as described in any one of claims 1-4.