A simulation method of a wet thermal oxidation process of single crystal silicon
By constructing a single-crystal silicon model to simulate the wet oxygen thermal oxidation process, the structural parameters of the oxide layer were obtained, which solved the problem of difficulty in analyzing the existence form and electronic properties of H in the existing technology, and realized the deep optimization and control of the oxide layer.
Patent Information
- Application Number
- CN202210762598.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-30
- Publication Date
- 2025-10-24
- Estimated Expiration
- 2042-06-30
AI Technical Summary
Existing technologies make it difficult to deeply analyze and control the existence form and electronic properties of element H in the wet oxygen thermal oxidation process, which affects the oxide layer structure and device performance.
A single-crystal silicon model was constructed, and the reaction of O2 and H2O molecules with the single-crystal silicon surface was simulated using the reactive force field molecular dynamics method to generate an oxide layer. By obtaining the number of Si-H bonds and Si-OH bonds, a deeper analysis of the existence form and electronic properties of H was achieved.
This study enables in-depth analysis of the existence form and electronic properties of H in the oxide layer generated by the wet oxygen thermal oxidation process, providing theoretical guidance, a basis for optimizing the actual process, and preventing H from entering the interior of the oxide layer.
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Figure CN115206447B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of simulation technology of silicon process, in particular to a simulation method of a wet oxygen thermal oxidation process of monocrystalline silicon. BACKGROUND
[0002] There are many methods for generating an oxide layer on a silicon surface, among which the thermal oxidation method is widely used. The thermal oxidation method includes dry oxygen thermal oxidation and wet oxygen thermal oxidation. The growth rate of the dry oxygen thermal oxidation method will rapidly decrease when the oxide layer grown on the silicon surface reaches a certain thickness, which often leads to the oxide layer thickness not meeting the requirements. The wet oxygen thermal oxidation method can generate an oxide layer at a faster rate and can meet the requirements of generating an oxide layer with a certain thickness. However, in the wet oxygen thermal oxidation process of silicon, element H is easy to enter the inside of the oxide layer, which affects the structure of the oxide layer and the performance of the corresponding device. Therefore, the study on the existence form and electronic properties of element H in the oxide layer is an important aspect of optimizing silicon-based devices. However, it is very difficult to determine the existence form and physical properties of element H in experiments. It is difficult to analyze and control the existence form and electronic properties of element H in depth, so as to achieve the purpose of economically and efficiently predicting and optimizing the device. SUMMARY
[0003] The problem solved by the present application is how to realize the acquisition and analysis of the existence form and electronic properties of H in the oxide layer generated by the wet oxygen thermal oxidation process.
[0004] To solve the above problems, the present application provides a simulation method of a wet oxygen thermal oxidation process of monocrystalline silicon, comprising the following steps:
[0005] Step S1: constructing a model of monocrystalline silicon with a vacuum layer on the surface, in the model, using the reaction force field molecular dynamics method to make the atomic positions and stress states of the monocrystalline silicon in a starting state, and then heating the model to a reaction temperature to make the model in an equilibrium state;
[0006] Step S2: under constant temperature conditions, at intervals of a preset reaction time, repeatedly emitting O2 molecules and H2O molecules to the surface of the monocrystalline silicon at a gas rate corresponding to the temperature at random positions of the vacuum layer to make the surface of the monocrystalline silicon undergo an oxidation reaction, and after the reaction is completed, keeping the model in the constant temperature conditions until the model state is balanced, and after annealing, obtaining an oxidation sample; the oxidation sample includes an oxide layer;
[0007] Step S3: acquiring the structure parameters of the oxide layer, repeating steps S1 to S2, acquiring and analyzing the structure parameters of the oxide layer, and the structure parameters at least include the number of Si-H bonds and Si-O-H bonds.
[0008] Further, in step S1, the vacuum layer is arranged on any surface of the monocrystalline silicon.
[0009] Further, in step S1, after the atomic positions and force states of the single crystal silicon are brought to the initial state by the reactive force field molecular dynamics method, the method comprises the following steps:
[0010] The atomic positions of the single crystal silicon are optimized by the reactive force field molecular dynamics method, and the force of each atom is brought to zero after relaxation.
[0011] Further, in step S1, the reaction temperature ranges from 1000K to 1300K.
[0012] Further, in step S2, the O2 molecules and H2O molecules are emitted to the surface of the single crystal silicon at the gas rate corresponding to the temperature at random positions of the vacuum layer to cause oxidation reaction on the surface of the single crystal silicon, comprising the following steps:
[0013] The O2 molecules and H2O molecules are emitted to the surface of the single crystal silicon at the gas rate corresponding to the reaction temperature at random positions of the vacuum layer, so that the O2 molecules and / or H2O molecules collide with the atoms of the single crystal silicon, and if the O2 molecules or H2O molecules do not react with the atoms of the single crystal silicon, the unreacted O2 molecules or H2O molecules are removed; the above steps are repeated until the oxidation reaction on the surface of the single crystal silicon is complete.
[0014] Further, in step S2, the ratio of O2 molecules to H2O molecules is (1-2) to (1-4).
[0015] Further, in step S2, the number of repetitions ranges from 500 to 2000 times.
[0016] Further, in step S2, after the reaction is completed, the single crystal silicon is kept in a constant temperature condition for a holding time ranging from 300ps to 600ps.
[0017] Further, in step S1, the thickness of the vacuum layer ranges from 3nm to 6nm.
[0018] Further, in step S3, the annealing method comprises cooling to 0K after annealing to room temperature.
[0019] The simulation method of the single crystal silicon wet oxygen thermal oxidation process has the advantages that the model of the single crystal silicon is constructed, the O2 molecules and H2O molecules react with the atoms on the surface of the single crystal silicon in the vacuum layer to generate the oxidation sample, the actual single crystal silicon wet oxygen thermal oxidation process is simulated, the process data of the oxidation layer generation process at the atomic and molecular levels are obtained through the simulation process, the structure parameters of the oxidation layer are obtained, the structure parameters of H include the number of Si-H bonds and Si-O-H bonds, the existence form and electronic properties of H in the oxidation layer generated by the wet oxygen thermal oxidation process are obtained, the existence form and electronic properties of H in the oxidation layer are analyzed in depth after repeated acquisition, the purpose of economically and efficiently predicting and optimizing the corresponding device is achieved. The present application starts from the microscopic point of view, controls and analyzes the existence form and electronic properties of H in the oxidation layer, and then avoids and controls the number and form of H entering the inside of the oxidation layer, thereby providing theoretical guidance for the optimization of the actual wet oxygen thermal oxidation process. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 The simulation method of the single crystal silicon wet oxygen thermal oxidation process in the embodiment of the present application is shown in the flowchart.
[0021] Figure 2 The configuration structure diagram before the single crystal silicon wet oxygen thermal oxidation in the embodiment of the present application is shown.
[0022] Figure 3 The configuration structure diagram during the single crystal silicon wet oxygen thermal oxidation process in the embodiment of the present application is shown.
[0023] Figure 4 The configuration structure diagram after the single crystal silicon wet oxygen thermal oxidation in the embodiment of the present application is shown.
[0024] Figure 5 The concentration distribution of various defects in the oxidation layer and the concentration distribution of Si-H and O-H in the embodiment of the present application are shown in the statistical diagram.
[0025] Figure 6 The statistical analysis diagram of the bond angle of the bonded atoms in the oxidation layer in the embodiment of the present application is shown.
[0026] Figure 7 The statistical analysis diagram of the bond length of the bonded atoms in the oxidation layer in the embodiment of the present application is shown. DETAILED DESCRIPTION
[0027] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.
[0028] It is to be noted that the description of the term "some specific embodiments" in the description of the embodiments of the present application means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above-mentioned terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.
[0029] As shown in Figure 1 and Figure 2 The embodiment of the present application provides a simulation method of a single crystal silicon wet oxygen thermal oxidation process, comprising the following steps:
[0030] Step S1: a model of single crystal silicon with a vacuum layer on the surface is constructed, in the model, the atomic position and stress state of the single crystal silicon are brought to the initial state by using the reaction force field molecular dynamics method, and then the model is heated to the reaction temperature to bring the model to the equilibrium state;
[0031] Step S2: under constant temperature conditions, O2 molecules and H2O molecules are emitted to the surface of the single crystal silicon at a random position of the vacuum layer at a gas rate corresponding to the temperature at intervals of a preset reaction time, so that the single crystal silicon surface is oxidized, and after the reaction is completed, the model is kept under constant temperature conditions until the model state is balanced, and after annealing, an oxidation sample is obtained; the oxidation sample comprises an oxidation layer;
[0032] Step S3: the structure parameters of the oxidation layer are obtained, steps S1 to S2 are repeated, the structure parameters of the oxidation layer are obtained and analyzed, and the structure parameters at least include the number of Si-H bonds and Si-O-H bonds.
[0033] The simulation method of the single crystal silicon wet oxygen thermal oxidation process described in the embodiment of the present application realizes the simulation of the actual single crystal silicon wet oxygen thermal oxidation process method by constructing the model of the single crystal silicon, simulating the reaction of O2 molecules and H2O molecules with the atoms on the surface of the single crystal silicon in the vacuum layer, and generating the oxidation sample process. The process data of the oxidation layer generation process at the atomic and molecular levels obtained through the above simulation process are used to obtain the structure parameters of the oxidation layer related to H, including the number of Si-H bonds and Si-O-H bonds, so as to realize the acquisition of the existence form and electronic properties of H in the oxidation layer generated by the wet oxygen thermal oxidation process. After repeated multiple times, the deep analysis of the existence form and electronic properties of H in the oxidation layer is realized through the acquisition of the existence form and electronic properties of H in the oxidation layer, so as to achieve the purpose of economically and efficiently predicting and optimizing the corresponding device. The present application starts from the microcosmic perspective, controls and analyzes the existence form and electronic properties of H in the oxidation layer, and then avoids and controls the number and form of H entering the inside of the oxidation layer, thereby providing theoretical guidance for the optimization of the actual wet oxygen thermal oxidation process.
[0034] In step S1 of this embodiment, a model of single crystal silicon is constructed using the LAMMPS program software, and the initial position optimization of the atoms of the single crystal silicon and the vacuum layer on the surface thereof is performed using the reactive force field molecular dynamics method. After balancing the force state of the atoms, the model is raised to the reaction temperature and then relaxed to an equilibrium state, so as to ensure the stability and repeatability of the model at each stage.
[0035] In step S2 of this embodiment, after reaching the reaction temperature, the temperature is kept constant, and O2 molecules and H2O molecules with a certain proportion are emitted to the surface of the single crystal silicon at a gas rate corresponding to the temperature at random positions of the vacuum layer. The emission direction is preferably a direction perpendicular to the surface of the single crystal silicon and downward. The above emission step is repeated to cause an oxidation reaction on the surface of the single crystal silicon and generate an oxidation layer with a certain thickness. The temperature is continuously kept constant, and after the reaction system state of the model is balanced, annealing is performed to finally obtain an oxidation sample. The oxidation sample includes an oxidation layer, unoxidized silicon, and a transition layer between the unoxidized silicon and the completed oxidation layer. In the simulated oxidation sample, the structure of the oxidation sample can be clearly observed, which is microscopic data at the atomic level, greatly improves the depth of analysis, and is beneficial to the comprehensive understanding of the oxidation sample.
[0036] In step S3 of this embodiment, the structure parameters of the oxidation layer are specifically obtained, especially the related data of H, including the number of Si-H bonds and Si-O-H bonds. Through repeated experiments and adjustment of the process parameters in the model simulation process, the process parameters that have an influence on the entry of H into the oxidation layer can be statistically analyzed, and the corresponding rules can be summarized, which has a guiding significance for the content and distribution of H in the oxidation layer of the single crystal silicon prepared by the wet oxygen and thermal oxidation process.
[0037] In some specific embodiments, in step S1, the vacuum layer is arranged on any surface of the single crystal silicon. Thus, the position of the vacuum layer can be flexibly arranged according to needs, which is beneficial to intuitively observing the changes in the reaction process and obtaining the corresponding structure parameters or process parameter data.
[0038] In some specific embodiments, in step S1, the atomic position and force state of the single crystal silicon are brought to the initial state using the reactive force field molecular dynamics method, which includes:
[0039] The atomic position of the single crystal silicon is optimized using the reactive force field molecular dynamics method, and the force of each atom is zero after relaxation.
[0040] Thus, the force state of the atoms in the initial state is controlled and accurately, the interference of the initial state on the subsequent oxidation process is reduced, and the influence of each process parameter in the reaction process on the final oxidation sample is accurately controlled.
[0041] In some specific embodiments, in step S1, the reaction temperature ranges from 1000K to 1300K. In this way, each reaction molecule or atom in the oxidation reaction is in an activated state, which facilitates the smooth progress of the reaction.
[0042] In some specific embodiments, in step S2, O2 molecules and H2O molecules are emitted to the monocrystalline silicon surface at a gas rate corresponding to the temperature at random positions of the vacuum layer, so that the monocrystalline silicon surface undergoes an oxidation reaction, including the following steps:
[0043] O2 molecules and H2O molecules are emitted to the monocrystalline silicon surface at a gas rate corresponding to the reaction temperature at random positions of the vacuum layer, so that O2 molecules and / or H2O molecules collide with atoms of the monocrystalline silicon. If O2 molecules or H2O molecules do not react with atoms of the monocrystalline silicon, the unreacted O2 molecules or H2O molecules are removed. The above steps are repeated until the oxidation reaction on the monocrystalline silicon surface is complete.
[0044] In this way, the probability of effective reaction molecules is improved, and after removal, the influence on the emission path and movement path of the repeatedly emitted O2 molecules and / or H2O molecules is reduced, further improving the probability of reaction occurrence.
[0045] In some specific embodiments, in step S2, the ratio of O2 molecules to H2O molecules is (1-2):(1-4). In the present embodiment, O2 molecules and H2O molecules are at the same temperature, and the movement rate of H2O molecules is usually 1.33 times that of O2 molecules. Therefore, according to the influence of the movement rate on the number of collisions and the probability of reaction, the ratio of O2 molecules to H2O molecules is optimized, which is beneficial to improve the reaction rate.
[0046] In some specific embodiments, in step S2, the number of repetitions ranges from 500 to 2000 times. In this way, O2 molecules and H2O molecules sufficiently react with atoms of the monocrystalline silicon, and an oxidation sample with a suitable thickness requirement is obtained.
[0047] In some specific embodiments, in step S2, after the reaction is completed, the holding time of the model under the constant temperature condition ranges from 300ps to 600ps. In this way, a reasonable relaxation time is given to the reaction system, which is beneficial to the balance of the structure state in the model after the reaction, and the accuracy and repeatability of the structure parameters obtained for analysis.
[0048] In some specific embodiments, in step S1, the thickness of the vacuum layer ranges from 3nm to 6nm. In this way, O2 molecules and H2O molecules have sufficient movement space to react with atoms of the monocrystalline silicon, effectively simulating the actual wet oxygen and thermal oxidation process method, and realizing the generation process of the oxidation layer on the monocrystalline silicon surface.
[0049] In some specific embodiments, in step S3, the annealing manner comprises annealing to room temperature and then cooling to 0K. In this way, the structure of the oxidized sample is optimized, which is conducive to reducing defects in the structure.
[0050] Embodiment 1
[0051] The simulation method of the wet thermal oxidation process of single crystal silicon in this embodiment comprises the following steps:
[0052] A model of single crystal silicon is constructed using LAMMPS software, and the interaction between atoms is described using a reaction force field of molecular dynamics. A 3.3nm×3.3nm×3.3nm single crystal silicon is oxidized by a wet thermal oxidation process to simulate the flow of hot oxygen, which contains 3456 Si atoms, and a 6nm thick vacuum layer is added, as shown in Figure 2 . The incident direction of O2 molecules and H2O molecules is along the direction of the inverse
[100] crystal direction, i.e. perpendicular to the silicon surface and moving downward, a total of 500 cycles, the reaction temperature is controlled at 1300K, the ratio of O2 molecules and H2O molecules in the wet oxygen is 1:2, and the configuration picture injected into the reaction is as shown in Figure 3 . The final atomic configuration of the wet thermal oxidation process is as shown in Figure 4 , and the thickness of the obtained SiO2 oxide layer is 4.8nm. Statistical analysis is performed on the atomic state of the oxidized oxide layer, and the density of various defects is as shown in Figure 5 . It can be seen that the number of Si-H bonds and Si-O-H bonds is relatively large. The analysis of bond angles is as shown in Figure 6 , and the blue and red in the figure represent the distribution characteristics of O-Si-O and Si-O-Si bond angles, respectively. It can be seen that the bond angle of O-Si-O is mainly distributed around 95.55 degrees, and the distribution of Si-O-Si bond angle is mainly around 142.64 degrees. The distribution of bond length is as shown in Figure 7 , and the bond length of Si-O bond is mainly distributed around 1.55.
[0053] Embodiment 2
[0054] The simulation method of the wet thermal oxidation process of single crystal silicon in this embodiment comprises the following steps:
[0055] The model of single crystal silicon is constructed by using LAMMPS software, the interaction between atoms is described by using the reaction force field of molecular dynamics, the wet oxygen thermal oxidation process is used to simulate the oxidation of the constructed 3.3nm*3.3nm*3.3nm single crystal silicon by flowing hot oxygen, a total of 3456 Si atoms are contained, and a 3nm thick vacuum layer is added. The incident direction of O2 molecules and H2O molecules is along the direction of inverse
[100] crystal direction, that is, perpendicular to the silicon surface and moves downward, a total of 2000 cycles are carried out, the reaction temperature is controlled at 1000K, the ratio of O2 molecules and H2O molecules in wet oxygen is 1:1. The thickness of the SiO2 oxide layer finally obtained by using the wet oxygen thermal oxidation process is 4.8nm. The atomic state of the oxide layer after oxidation is statistically analyzed, and the number of Si-H bonds and Si-O-H bonds and the distribution characteristics of O-Si-O and Si-O-Si bond angles are obtained.
[0056] Example 3
[0057] The simulation method of the wet oxygen thermal oxidation process of the single crystal silicon in this embodiment comprises the following steps:
[0058] The model of single crystal silicon is constructed by using LAMMPS software, the interaction between atoms is described by using the reaction force field of molecular dynamics, the wet oxygen thermal oxidation process is used to simulate the oxidation of the constructed 3.3nm*3.3nm*3.3nm single crystal silicon by flowing hot oxygen, a total of 3456 Si atoms are contained, and a 5nm thick vacuum layer is added, as shown in Figure 2 The incident direction of O2 molecules and H2O molecules is along the direction of inverse
[100] crystal direction, that is, perpendicular to the silicon surface and moves downward, a total of 1200 cycles are carried out, the reaction temperature is controlled at 1200K, the ratio of O2 molecules and H2O molecules in wet oxygen is 1:4, the thickness of the SiO2 oxide layer finally obtained by using the wet oxygen thermal oxidation process is 4.8nm. The atomic state of the oxide layer after oxidation is statistically analyzed, and the number of Si-H bonds and Si-O-H bonds and the distribution characteristics of O-Si-O and Si-O-Si bond angles are obtained.
[0059] Although the present application is disclosed as above, the protection scope of the present application is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and these changes and modifications will fall within the protection scope of the present application.
Claims
1. A simulation method of a wet oxygen thermal oxidation process of single crystal silicon, characterized in that, The steps include: Step S1: constructing a model of a single-crystal silicon with a vacuum layer on the surface using LAMMPS software. In the model, the atomic positions and stress states of the single-crystal silicon are set to an initial state using a reaction force field molecular dynamics method, and then heating the model to a reaction temperature to achieve an equilibrium state. Step S2: Under constant temperature conditions, at intervals of a preset reaction time, repeatedly emitting O2 molecules and H2O molecules toward the surface of the single crystal silicon at a gas rate corresponding to the temperature at random positions in the vacuum layer, causing an oxidation reaction on the surface of the single crystal silicon; after the reaction is completed, maintaining the model under constant temperature conditions until the model state is balanced, and annealing to obtain an oxidized sample; the oxidized sample includes an oxide layer, and the ratio of the O2 molecules to the H2O molecules is (1-2):(1-4); Step S3: Acquire the structural parameters of the oxide layer, repeat steps S1 to S2, acquire and analyze the structural parameters of the oxide layer, wherein the structural parameters at least include the number of Si-H bonds and Si-OH bonds.
2. The simulation method of claim 1, wherein the single crystal silicon wet oxidation process is a thermal oxidation process. In step S1, the vacuum layer is provided on any surface of the single crystal silicon.
3. The simulation method of claim 1, wherein the single crystal silicon wet oxidation process is a thermal oxidation process. In step S1, the step of using the reaction force field molecular dynamics method to make the atomic positions and stress states of the single crystal silicon in the initial state includes: The reaction force field molecular dynamics method is used to optimize the atomic positions of the single crystal silicon, and the force on each atom is made zero after relaxation.
4. The method of claim 1, wherein the method is characterized by: In step S1, the reaction temperature ranges from 1000-1300K.
5. The method of claim 1, wherein the method is characterized by: In step S2, the step of emitting O2 molecules and H2O molecules at a gas rate corresponding to the temperature toward the surface of the single crystal silicon at random positions of the vacuum layer to cause an oxidation reaction on the surface of the single crystal silicon comprises the following steps: The O2 molecules and the H2O molecules are emitted toward the surface of the single crystal silicon at a gas rate corresponding to the reaction temperature at random positions in the vacuum layer, so that the O2 molecules and / or the H2O molecules collide with the atoms of the single crystal silicon. If the O2 molecules or the H2O molecules do not react with the atoms of the single crystal silicon, the unreacted O2 molecules or the H2O molecules are removed; and the above steps are repeated until the oxidation reaction on the surface of the single crystal silicon is complete.
6. The method of claim 1, wherein the method is used to simulate a thermal oxidation process of single crystal silicon in wet oxygen. In step S2, the number of repetitions ranges from 500 to 2000 times.
7. The method of claim 1, wherein the method is used to simulate a thermal oxidation process of single crystal silicon in wet oxygen. In step S2, after the reaction is completed, the model is kept at a constant temperature for a period of time ranging from 300 to 600 ps.
8. The method of claim 1, wherein the method is used to simulate a thermal oxidation process of single crystal silicon in wet oxygen. In step S1, the thickness of the vacuum layer is in the range of 3-6 nm.
9. The method of claim 1, wherein the method is used to simulate a thermal oxidation process of single crystal silicon in wet oxygen. In step S2, the annealing method includes annealing to room temperature and then cooling to 0K.