A simulation calculation method for electron-hole pair yield in semiconductor devices

Abstract

The present invention provides a simulation calculation method for the electron-hole pair yield in a semiconductor device, comprising the following steps: measuring the thickness of the semiconductor device to be tested and confirming its material properties; in a Geant4 environment, constructing a structural model of the semiconductor device according to the parameters obtained in step S1; selecting different radiation particles to be incident on the structural model, and calculating the total positive charge and the number of electron-hole pairs per unit distance; calculating the position where ionization occurs through Geant4, and calculating its average value, and taking the average value as an adjustable parameter b; substituting the number of electron-hole pairs and the adjustable parameter b into the Jaffe electron-hole pair composite formula, and calculating the electron-hole pair yield under different electric field strength conditions. The calculation method of the electron-hole pair yield provided by the present invention has simple steps, is easy to operate, can greatly reduce the cost of the experiment, and has high calculation efficiency, which is of great significance to the research on semiconductor device damage and space environment simulation.

Description

Technical Field

[0001] The present invention relates to the technical field of space environment effects, and in particular to a method for simulating and calculating the yield of electron-hole pairs in a semiconductor device. Background Art

[0002] During the space orbit, the spacecraft will be affected by various particle radiations such as electrons, protons, heavy ions and gamma rays, and the electronic components will be degraded to a certain extent after being exposed to particle radiation. When different types of space charged particles act on key materials or devices on the spacecraft at the same time, it is easy to cause space comprehensive environmental effects, such as ionization / displacement synergy effect.

[0003] Most high-energy particles mainly cause ionization damage when interacting with electronic components, and the ionization damage of electronic components can be evaluated by using linear energy transfer (LET). In the prior art, the commonly used method for evaluating the radiation effects of electronic components is mainly through experimental methods, and the cost of space irradiation experiments is very high. The cost of using simulation calculation methods for irradiation experiments is low, and it has become a key research direction. However, in the simulation calculation methods in the prior art, it takes a lot of computing time to simulate and calculate complex device structures.

[0004] In recent years, as the size of circuits has become smaller and smaller, a single heavy-charge particle in the natural environment can also cause the circuit signal to flip. Among them, the flip of the circuit signal is often caused by the electrical signal caused by the unrecombined electron-hole pairs entering the circuit. Therefore, calculating the recombination and yield of electron-hole pairs through simulation calculation has important engineering value and scientific significance for studying the basic theory and evaluation methods of the effects of the space comprehensive environment on materials, as well as revealing the basic laws of material performance degradation under the space comprehensive environment and the physical nature of the comprehensive effects of various space environments. Summary of the invention

[0005] The problem solved by the present invention is how to provide a method for simulating and calculating the yield of electron-hole pairs in a semiconductor device which has simple steps, is easy to operate and has high calculation efficiency.

[0006] In order to solve at least one aspect of the above problems, the present invention provides a method for simulating and calculating the electron-hole pair yield in a semiconductor device, comprising the following steps:

[0007] Step S1, measuring the thickness of the semiconductor device to be tested and confirming its material properties;

[0008] Step S2, in the Geant4 environment, constructing a structural model of the semiconductor device according to the parameters obtained in step S1;

[0009] Step S3, selecting different radiation particles to be incident on the structural model, and calculating the total positive charge amount and the number of electron-hole pairs per unit distance;

[0010] Step S4, using Geant4 to calculate the position where ionization occurs, and to calculate the average value thereof, and to use the average value as an adjustable parameter b;

[0011] Step S5, substituting the number of electron-hole pairs and the adjustable parameter b into the Jaffe electron-hole pair compound formula to calculate the electron-hole pair yields under different electric field strength conditions.

[0012] Preferably, in step S2, the semiconductor device is simplified into a parallel plate structure model according to the parameters obtained in step S1.

[0013] Preferably, in step S3, the radiation particles include electrons, protons, heavy ions or gamma rays.

[0014] Preferably, the material of the semiconductor device includes silicon dioxide.

[0015] Preferably, in step S3, the energy deposition is calculated for the structure model, and then the energy deposition is divided by the thickness of the structure model to obtain the LET value, and then the total positive charge and the number of electron-hole pairs per unit distance are obtained by the following formula:

[0016]

[0017] in, is the energy loss per unit path, 18ev is the minimum energy of the electron-hole pair generated by the silicon dioxide material, θ is the angle between the incident particle and the electric field, l ox is the thickness of the silicon dioxide oxide layer, 1.6×10 -19 Coulomb / hole means that the charge carried by each hole is 1.6×10 -19 Kulun.

[0018] Preferably, the LET values ​​at different depths are calculated by performing energy deposition calculation on the structural model of the parallel plates using the dE / dx formula.

[0019] Preferably, in step S4, each particle is tracked by Geant4, so as to calculate the position where each particle is ionized and calculate the average value, and use the average value as the adjustable parameter b.

[0020] Preferably, in step S5, the Jaffe electron-hole pair recombination formula is:

[0021]

[0022] Among them, Y is the yield of escaping electron-hole pair recombination, N0 is the number of electron-hole pairs generated per centimeter, e is the charge, ε is the relative dielectric constant, ε0 is the vacuum dielectric constant, b is an adjustable parameter, E is the applied electric field, and θ is the angle between the incident particle and the electric field.

[0023] The present invention uses the Monte Carlo method in Geant4 to simulate the irradiation test process of particles incident on semiconductor devices, calculates the total positive charge amount and the number of electron-hole pairs per unit distance in the irradiation test process through a formula, and then calculates the position where ionization occurs based on the result, takes the average value of the ionization position as an adjustable parameter b, and imports the Jaffe electron-hole pair composite formula to calculate the electron-hole pair yield under different electric field strengths. The method for calculating the electron-hole pair yield provided by the present invention has simple steps, is easy to operate, can greatly reduce the cost of the test, and has high calculation efficiency, which is of great significance to the research on semiconductor device damage and space environment simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of a method for simulating and calculating the yield of electron-hole pairs in a semiconductor device in an embodiment of the present invention;

[0025] Figure 2 Schematic diagram of a parallel plate structure model of a semiconductor device in an embodiment of the present invention;

[0026] Figure 3 is a curve diagram showing the variation of LET value with depth position in an embodiment of the present invention;

[0027] Figure 4 is a graph showing the position where ionization occurs in an embodiment of the present invention;

[0028] Figure 5 1 is a curve diagram of the electron-hole pair yield under different electric field strength conditions in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0030] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention can be combined with each other. The meanings of the terms "comprising", "including", "containing", and "having" are non-restrictive, that is, other steps and other ingredients that do not affect the results can be added. The above terms cover the terms "consisting of" and "essentially consisting of". Unless otherwise specified, materials, equipment, and reagents are commercially available.

[0031] The embodiment of the present invention provides a method for simulating and calculating the yield of electron-hole pairs in a semiconductor device, such as Figure 1 As shown, the following steps are included:

[0032] Step S1, measuring the thickness of the semiconductor device to be tested and confirming its material properties;

[0033] Step S2, in the Geant4 environment, constructing a structural model of the semiconductor device according to the parameters obtained in step S1;

[0034] Step S3, selecting different radiation particles to be incident on the structural model, and calculating the total positive charge amount and the number of electron-hole pairs per unit distance;

[0035] Step S4, using Geant4 to calculate the position where ionization occurs, and to calculate the average value thereof, and to use the average value as an adjustable parameter b;

[0036] Step S5, substituting the number of electron-hole pairs and the adjustable parameter b into the Jaffe electron-hole pair compound formula to calculate the electron-hole pair yields under different electric field strength conditions.

[0037] Specifically, in step S1, the material of the semiconductor device includes silicon dioxide, and its actual thickness is first measured before simulation calculation.

[0038] In step S2, according to the material of the semiconductor device obtained in step S1 and the thickness parameter obtained by measurement, a structural model of the semiconductor device is constructed in the Geant4 environment. In order to reduce the amount of calculation required in the simulation calculation process, the structural model of the semiconductor device is simplified to a parallel plate structure, wherein the parallel plate structure is as follows: Figure 2 As shown, the parallel plate structure can be used to obtain calculation results at different depths in the semiconductor device, simplifying the calculation steps.

[0039] In step S3, different radiation particle incident structure models are selected to perform irradiation simulation tests, and the total positive charge and the number of electron-hole pairs per unit distance are calculated through the irradiation simulation tests;

[0040] Among them, the radiation particles include electrons, protons, heavy ions or gamma rays. By calculating the energy deposition of the parallel plate structure model, the dE / dx value at different depths is calculated using the dE / dx formula, that is, the LET value, where dE represents the change in energy and dx represents the change in distance. According to the LET value, the total positive charge and the number of electron-hole pairs per unit distance are calculated using the following formula:

[0041]

[0042] in, is the energy loss per unit path, 18ev is the minimum energy of the electron-hole pair generated by the silicon dioxide material, θ is the angle between the incident particle and the electric field, l ox is the thickness of the silicon dioxide oxide layer, 1.6*10 -19 Coulomb / hole means that the charge carried by each hole is 1.6×10 -19 Kulun.

[0043] In step S4, each particle is tracked by Geant4, so as to calculate the position where each particle is ionized and calculate the average value, and use the average value as the adjustable parameter b.

[0044] In step S5, the number of electron-hole pairs and the adjustable parameter b calculated in step S4 are substituted into the Jaffe electron-hole pair recombination formula to calculate the electron-hole pair yield under different electric field strength conditions, wherein the Jaffe electron-hole pair recombination formula is:

[0045]

[0046] Among them, Y is the yield of escaping electron-hole pair recombination, N0 is the number of electron-hole pairs generated per centimeter, e is the charge, ε is the relative dielectric constant, ε0 is the vacuum dielectric constant, b is an adjustable parameter, E is the applied electric field, and θ is the angle between the incident particle and the electric field.

[0047] By using the Monte Carlo method in Geant4 to simulate the irradiation test process of particles incident on semiconductor devices, the total positive charge amount and the number of electron-hole pairs per unit distance in the irradiation test process are calculated by formula, and then the position where ionization occurs is calculated based on this result. The average value of the ionization position is used as an adjustable parameter b, and the Jaffe electron-hole pair composite formula is introduced to calculate the electron-hole pair yield under different electric field strengths. The method for calculating the electron-hole pair yield provided by the embodiment of the present invention has simple steps, is easy to operate, can greatly reduce the cost of the test, and has high calculation efficiency, which is of great significance to the research on semiconductor device damage and space environment simulation.

[0048] The following is a simulation calculation method for the electron-hole pair yield of a semiconductor device, in conjunction with a specific embodiment:

[0049] 1.1. Select the semiconductor device to be tested. The measured thickness is 10μm and the material is SiO2;

[0050] 1.2. In the Geant4 environment, a structural model with a material of SiO2 and a thickness of 10 μm was constructed. During the construction process, the structural model was simplified to a parallel plate structure, such as Figure 2 As shown;

[0051] 1.3. Select a proton incident structure model with an energy of 700KeV to conduct an irradiation simulation test. By calculating the energy deposition of the parallel plate structure model, the dE / dx value at different depths, i.e., the LET value, is calculated using the dE / dx formula, where dE represents the change in energy and dx represents the change in distance. According to the LET value, the total positive charge and the number of electron-hole pairs per unit distance are calculated using the following formula:

[0052]

[0053] in, is the energy loss per unit path, 18ev is the minimum energy of the electron-hole pair generated by the silicon dioxide material, θ is the angle between the incident particle and the electric field, l ox is the thickness of silicon dioxide oxide layer, 1.6*10 -19 Coulomb / hole means that the charge carried by each hole is 1.6×10-19 coulomb;

[0054] in, Figure 3 The curve diagram of LET value changing with depth is shown in Figure 2. Figure 3 It can be seen that the LET value gradually increases with the increase of depth, and when the depth reaches about 8μm, the LET value decreases rapidly. At a shallow depth, the number of electron-hole pairs generated is about 3×10 7 indivual;

[0055] 1.4. Calculate the position where ionization occurs through Geant4, and calculate its average value, and use the average value as the adjustable parameter b;

[0056] The position where ionization occurs is the perpendicular distance to the incident direction. Figure 4 The curve of the distance from the axis where ionization occurs is 1.28 nm after calculation, and 1.28 nm is used as the adjustable parameter b;

[0057] 1.5. Substitute the number of electron-hole pairs and the adjustable parameter b calculated in step 1.4 into the Jaffe electron-hole pair recombination formula to calculate the electron-hole pair yield under different electric field strength conditions, where the electric field range is 0.5-2.5 MeV / cm. The Jaffe electron-hole pair recombination formula is:

[0058]

[0059] Where Y is the yield of escaping electron-hole pair recombination, N0 is the number of electron-hole pairs generated per centimeter, e is the charge, ε is the relative dielectric constant, ε0 is the vacuum dielectric constant, b is an adjustable parameter, E is the applied electric field, and θ is the angle between the incident particle and the electric field;

[0060] Through calculation, the calculation result of electron-hole pair yield is obtained. Figure 5 It is a curve diagram of the electron-hole pair yield under different electric field strength conditions;

[0061] from Figure 5 It can be seen that when the electric field strength is small, the yield of electron-hole pairs is also small. As the electric field strength increases, the electron-hole pairs separate, resulting in an increase in yield. However, after the electric field strength increases to a certain level, the yield will not continue to increase, and saturation occurs.

[0062] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for simulating and calculating the yield of electron-hole pairs in a semiconductor device, characterized in that: The following steps are involved: Step S1, measuring the thickness of the semiconductor device to be tested and confirming its material properties; Step S2, in the Geant4 environment, constructing a structural model of the semiconductor device according to the parameters obtained in step S1; Step S3, selecting different radiation particles to be incident on the structural model, and calculating the total positive charge amount and the number of electron-hole pairs per unit distance; Step S4, using Geant4 to calculate the position where ionization occurs, and to calculate the average value thereof, and to use the average value as an adjustable parameter b; Step S5, substituting the number of electron-hole pairs and the adjustable parameter b into the Jaffe electron-hole pair compound formula to calculate the electron-hole pair yield under different electric field strength conditions; In the step S2, the semiconductor device is simplified into a parallel plate structure model according to the parameters obtained in the step S1; The material of the semiconductor device includes silicon dioxide; In step S3, the energy deposition is calculated for the structure model, and then the energy deposition is divided by the thickness of the structure model to obtain the LET value, and then the total positive charge and the number of electron-hole pairs per unit distance are obtained by the following formula: in, is the energy loss per unit path, 18ev is the minimum energy of the electron-hole pair generated by the silicon dioxide material, θ is the angle between the incident particle and the electric field, l ox is the thickness of the silicon dioxide oxide layer, 1.6×10 -19 Coulomb / hole means that the charge carried by each hole is 1.6×10 -19 Kulun.

2. The method for simulating and calculating the electron-hole pair yield in a semiconductor device according to claim 1, characterized in that: In step S3, the radiation particles include electrons, protons, heavy ions or gamma rays.

3. The method for simulating and calculating the electron-hole pair yield in a semiconductor device according to claim 1, characterized in that: By performing energy deposition calculation on the structural model of the parallel plate, the LET values ​​at different depths are calculated using the dE / dx formula.

4. The method for simulating and calculating the yield of electron-hole pairs in a semiconductor device according to claim 1, characterized in that: In step S4, each particle is tracked by Geant4, so as to calculate the position where each particle is ionized and calculate the average value, and use the average value as the adjustable parameter b.

5. The method for simulating and calculating the yield of electron-hole pairs in a semiconductor device according to claim 1, characterized in that: In step S5, the Jaffe electron-hole pair recombination formula is: Among them, Y is the yield of escaping electron-hole pair recombination, N0 is the number of electron-hole pairs generated per centimeter, e is the charge, ε is the relative dielectric constant, ε0 is the vacuum dielectric constant, b is an adjustable parameter, E is the applied electric field, and θ is the angle between the incident particle and the electric field.

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