Amorphous HFO2Si interface modification method, equipment and medium

Abstract

The invention relates to the field of semiconductor materials, and discloses an amorphous HFO2Si interface modification method, equipment and a medium, and the method comprises the following steps: building an amorphous HFO2Si interface; analyzing the interface key strength and electron gain and loss information of the building structure through the plane average differential charge density; a first position, a second position and a third position are selected on a built structure interface, three O vacancy defects of VO1, VO2 and VO3 are introduced, and the three different O vacancies form different bonds on the interface; analyzing the influence of the defect zones with three different defect structures on the electrical properties of the semiconductor material, and selecting the O vacancy defect at the introduction position with better influence; introducing H to passivate dangling bonds at O vacancy defects at introduction positions with relatively good influence to obtain a structure Vop; according to the invention, interface defects can be effectively reduced, the electron transmission efficiency is improved, and the stability of the device is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor materials, and in particular, to a method, device and medium for modifying the amorphous HfO₂Si interface. Background Art

[0002] In semiconductor materials, the intermediate states introduced by oxygen vacancy defects are usually located in the energy band gap and form so-called deep-level defects. These deep-level defects may act as non-ideal charge transport channels, leading to a significant increase in leakage current. Such an increase in leakage current not only affects the electrical performance of the device, but may also cause power loss and heating, thereby affecting the overall device stability and efficiency.

[0003] The energy band alignment mode of the interface is crucial for the electronic characteristics of semiconductor devices. By adjusting the energy band alignment mode of the interface, the height of the Schottky barrier may be reduced, thus directly affecting the injection characteristics and efficiency of carriers. The reduced Schottky barrier may lead to a reduction in the thermodynamic or kinetic barriers during the carrier injection process, thereby increasing the injection efficiency of the current, but may also increase the energy loss caused by non-ideal injection, having a negative impact on the device performance.

[0004] Under high temperature and high electric field conditions, oxygen vacancy defects may further aggregate. This defect aggregation will lead to the deterioration of the semiconductor material interface. Over time, these aggregated defects may form conductive channels, significantly reducing the insulation performance of the material, accelerating the aging process of the device, and thus seriously affecting the reliability and life of the device. This interface deterioration is a key limiting factor for the long-term operation stability of the device and needs to be fully considered during the material design and device packaging processes. Summary of the Invention

[0005] The purpose of the present invention is to propose a method for modifying the amorphous HfO₂Si interface to solve the technical problem that under high temperature and high electric field conditions, the aggregation of oxygen vacancy defects leads to the optimization of the semiconductor material interface, thereby reducing the life of the semiconductor material.

[0006] Specifically, a method for modifying the amorphous HfO₂Si interface provided by the present invention includes the following steps:

[0007] S1. Build an amorphous HfO₂Si interface;

[0008] S2. Analyze the interface bond strength and electron gain and loss information of the built structure through plane-averaged differential charge density;

[0009] S3. Select three different positions, namely the first, second, and third, on the built structure interface and introduce V O1 、V O2 、V O3There are three types of O vacancy defects, and the bonding of three different O vacancies at the interface is different;

[0010] S4. Analyze the influence of the defect bands of three different defect structures on the electrical properties of semiconductor materials, and select the O vacancy defect at the introduction position with a better influence;

[0011] S5. Introduce H to passivate the dangling bonds at the O vacancy defect at the introduction position with a better influence, and obtain structure V op 。

[0012] A storage medium stores instructions and data for implementing a method for modifying the amorphous HfO2Si interface.

[0013] An amorphous HfO2Si interface modification device includes: a processor and the storage medium; the processor loads and executes the instructions and data in the storage medium for implementing a method for modifying the amorphous HfO2Si interface.

[0014] The beneficial effects provided by the present invention are: a specific passivation scheme is proposed. This scheme is not just a conventional application of hydrogen passivation, but optimizes the special passivation requirements for oxygen vacancies on the HfO / Si interface, and verifies its effectiveness and feasibility through experimental data.

[0015] The H passivation scheme proposed by the present invention has clear operation steps and detailed parameter adjustments, enabling the method to achieve an ideal passivation effect in the HfO / Si interface. By comparing the experimental results, the present invention can effectively reduce interface defects, improve electron transport efficiency, and significantly improve the stability of the device. Therefore, this scheme not only has guiding significance in theory, but also has high feasibility and practical application value in actual operation. Description of the Drawings

[0016] Figure 1 is a schematic diagram of the process of the method of the present invention;

[0017] Figure 2 is a schematic diagram showing the variation of the total mobility and component mobility of the Perfect structure, three oxygen defect structures (VO1, VO2, and VO3), and the passivated structure VOP of a-HfO2 / Si with the defect concentration at 300 K;

[0018] Figure 3 is a schematic diagram of the interface structure after adding O vacancies in the present invention;

[0019] Figure 4 is a schematic diagram of the operation of the hardware device in the embodiment of the present invention. Detailed Embodiments

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0021] Before formally elaborating on the present invention, first, a general description of the solution of the present invention is given for easy understanding.

[0022] Please refer to Figure 1 , a method for modifying the amorphous HfO₂Si interface provided by the present invention includes:

[0023] S1. Construct an amorphous HfO₂Si interface;

[0024] It should be noted that in the present invention, an HfO₂Si interface matching the experimental data is specifically constructed in combination with the experimental data, and the RDF of the constructed interface shows that the bonding is consistent with the experimental data.

[0025] Specifically, for the amorphous HfO₂ / Si interface constructed by the present invention, the Si-O bond length at the interface is Compared with that in α-quartz SiO₂ and that in HfSiO₄

[0026] The Si-Hf bond length at the interface is Compared with 2.10 in HfSiO₄ and Judge whether the optimized interface forms a SiO₂ or HfSiO₄ phase.

[0027] Analyze whether the band edge contribution is mainly from Si, and judge whether the interface is of type-i or type-ii characteristics.

[0028] It should be noted that the analysis of the interface band edge contribution can start from the PDOS, and observe what atoms contribute to the VBM and CBM. In the PDOS graph, find the PDOS peaks near the highest point of the valence band and see which atoms' which orbitals (such as s, p, d orbitals) these peaks are mainly contributed by. Similarly, in the PDOS graph, find the position where the conduction band starts and analyze the PDOS of this part. Determine which atoms' which orbitals mainly contribute to the electron states at the lowest point of the conduction band.

[0029] Whether it is a type-I or type-II energy band is mainly determined by the band edges of the PDOS. In type-I energy band alignment, the lowest point of the conduction band of one semiconductor is lower than that of the other semiconductor, and the highest point of its valence band is also higher than that of the other semiconductor. This means that the conduction band and valence band of both semiconductors are surrounded by one semiconductor. In type-II energy band alignment, the lowest point of the conduction band of one semiconductor is lower than that of the other semiconductor, but the highest point of its valence band is lower than that of the other semiconductor. In this way, electrons and holes are located in different semiconductors, and neither the conduction band nor the valence band is completely surrounded by the other.

[0030] The radial distribution function (RDF) of the calculated structure is analyzed to see if the RDF peaks of Hf-O and the RDF peaks of O-O and Hf-Hf match the experimental data. Specifically, in step S1, RDF calculation is introduced to analyze the bonding situation of the structure, and the calculation formula is:

[0031] Assume that the coordinates of the positions of two atoms in three-dimensional space are r a and r b , then the distance r ab between them can be obtained by the following formula:

[0032] r ab = |r a - r b |

[0033] The radial distribution function g(r) describes the spatial distribution of neighboring atoms around an atom. It represents the change in atomic density within a specific distance range r relative to the density under the ideal gas model:

[0034]

[0035] where: g(r) is the radial distribution function, representing the ratio of the atomic density to the density under the ideal gas state within the distance range from r to r+dr. V is the volume of the system. N is the total number of atoms in the system. is the atomic density of the system. dN(r) is the number of atom pairs within the distance range from r to r+dr. represents the rate of change of the number of atom pairs within the range from r to r+dr with respect to r.

[0036] S2. Analyze the interfacial bond strength and electron gain and loss information of the built structure through the planar average differential charge density;

[0037] The calculation process of the overall planar average differential charge described in step S2 is as follows:

[0038] The calculation formula of the overall planar average differential charge described in step S2 is:

[0039] Suppose there are two charge density distributions: an original charge density distribution ρ0(r), and another charge density distribution ρ1(r) after some treatment (such as molecular adsorption or reaction). Then the planar-averaged differential charge density Δρ(r) is calculated as:

[0040] Δρ(r) = ρ1(r) - ρ0(r)

[0041] This is the difference in point charge density, which describes the change in charge during different electronic structure changes.

[0042] To average the differential charge over a certain plane, usually a direction is chosen (generally the z-axis direction), and then the integration is carried out along this direction. Then the planar-averaged differential charge density can be expressed as:

[0043]

[0044] where: A is the cross-sectional area of the plane, usually the cross-sectional area of the unit cell. Δρ(r) is the difference in point charge density, r = (x, y, z) is the position coordinate in space. The integration is carried out along the plane direction (usually the x and y directions) to obtain the average value on a specific z-plane.

[0045] Summarizing the above formulas, so in practical applications, the following integral expression is usually used to calculate the charge difference averaged over the plane:

[0046]

[0047] where L x 、L y are the dimensions in the plane direction respectively; ρ1 and ρ0 represent the charge densities of different systems or the charge densities of the same system in different states. Here, ρ1 represents the charge density after the overall structure optimization, and ρ0 represents the spherically symmetric charge density of each atom forming the overall structure in the free state, also known as the deformation charge density.

[0048] S3. Select the first, second, and third different positions at the constructed structural interface, and introduce V O1 、V O2 、V O3 three kinds of O vacancy defects. The three different O vacancies have different bonding at the interface;

[0049] It should be noted that the O vacancy in the V o1 structure is far from the interface and close to the HFO2 region, and does not participate in the interface bonding; V O2 and V O3The oxygen vacancies in the structure are close to the interface, affecting the formation of Hf-O and Si-O bonds. Here, being close to the interface specifically means that the distance from the interface is less than a preset value, and being far from the interface specifically means that the distance from the interface is greater than the preset value; being close to the HfO2 region specifically means that the distance from the HfO2 region is less than a preset value.

[0050] As an embodiment, three different positions are selected at the structure interface to introduce V O1 , V O2 , V O3 Three kinds of O vacancy defects. The selection of O vacancy defects needs to have a certain representativeness. There should be a large gap in the distances of the three O vacancies from the Si interface. V O1 The oxygen vacancy in the structure is slightly far from the interface and closer to the HfO2 region, and hardly participates in the interface bonding. While V O2 and V O3 The oxygen vacancies in the structure are close to the interface, significantly affecting the formation of Hf-O and Si-O bonds.

[0051] Because the defects close to the interface have a more significant impact on the device performance, in the present invention, the spatial distances of V O1 , V O2 and V O3 from the interface are respectively and Their impacts on the interface chemical bonds are significantly different. V O1 is slightly far from the interface, but does not significantly interfere with the formation of the interface chemical bonds. V O2 and V O3 have the farthest and nearest spatial distances from the interface among the three, and directly affect the formation of the interface Hf-O and Si-O bonds.

[0052] S4. Analyze the influence of the defect bands of the three different defect structures on the electrical properties of the semiconductor material, and select the O vacancy defect at the introduction position with a better influence;

[0053] In the present invention, analyze the influence of the O vacancies on the band gap properties of the structure, whether it changes the structure from an indirect band gap to a direct band gap, or introduces a flat band in the energy band. It is mainly analyzed and selected by calculating the band and PDOS of the three defect structures.

[0054] Whether the VBM and CBM of the energy band diagram are aligned at the same k-point indicates whether it is a direct bandgap or an indirect bandgap. If they are aligned at the same k-point, it is a direct bandgap; otherwise, it is an indirect bandgap. The observation of flat bands can also be carried out through energy band analysis, focusing on observing the energy bands near the Fermi level to see if the energy change of a certain energy band is very small within a certain wave vector range, that is, the band is almost horizontal within this range, then this can be regarded as a flat band. Flat bands often represent the localization of charges, that is, defect states. The contribution of atoms to the flat band is judged by observing the corresponding peaks in the PDOS.

[0055] S5. Introduce H to passivate the dangling bonds at the O vacancy defects at the better-affected introduction positions to obtain Structure V op 。

[0056] As an example, the present invention selects to introduce H to passivate the dangling bonds at the V O2 vacancies to obtain Structure V OP , and the flat band after passivation is solved. The passivation well solves the dangling bonds at the O vacancies;

[0057] The verification process of the present invention is as follows:

[0058] S51. Calculate the band offset of V OP and V O1 , V O2 , V O3 to judge whether the passivation increases the energy barrier of the tunneling effect;

[0059] Please refer to Table 1.

[0060] Table 1. The CBO and VBO of the Perfect structure of a-HfO2 / Si, the three oxygen defect structures (V O1 , V O2 and V O3 ) in the interface, and the oxygen vacancy passivation structure V O2 of V OP

[0061]

[0062] Table 1 shows the calculated and compared band offsets CBO and VBO of the Perfect structure, the three oxygen vacancy defect structures (V O1 , V O2 and V O3 ) in the interface, and the oxygen vacancy passivation structure VOP of V O2 .

[0063] By comparison, it is found that compared with the Perfect structure, the oxygen vacancies of V O2 and V O3 increase the CBO and decrease the VBO. For example, V O2The CBO of [object] increased by 26.987%, and the VBO decreased by 14.766%. For V O1 The CBO of the [object] structure decreased, and the VBO increased. For V O2 After H passivation, for V OP the CBO decreased by 30.309%, and the VBO increased by 20.843%. The band offset size of V OP is closer to that of the Perfect structure, indicating that H passivation can significantly regulate the defect structure.

[0064] S52. Calculate the Bader charges of the four structures, analyze how H bonds with the dangling bonds at the O vacancy, and analyze the effectiveness of the passivation effect;

[0065] The calculation formula for the Bader charge described in step S52 is as follows:

[0066] The Bader charge calculation is based on the following steps:

[0067] Electron density distribution: Assume that the total electron density of the system is ρ(r), which is a function of the spatial position r and usually comes from the self-consistent calculation of VASP.

[0068] Zero-gradient surface: By calculating the gradient of the electron density the zero-gradient surface can be defined, that is, the surface where the gradient is zero. These surfaces divide the space into several Bader regions. Each Bader region corresponds to an atom.

[0069]

[0070] Atomic charge assignment: The Bader charge is obtained by integrating the electron density within each Bader region. Given the Bader region i, the charge Q i in this region is calculated by the following formula:

[0071]

[0072] where V i is the Bader region associated with the i-th atom.

[0073] S53. Calculate the first-principles carrier mobility of the four structures and test how H passivation improves the carrier transport of the structure.

[0074] Step 53 calculates the carrier mobility considering four scattering mechanisms, namely acoustic deformation potential scattering (ADP), piezoelectric scattering (PIE), polar optical phonon scattering (POP), and ionized impurity scattering (IMP).

[0075] Among them, ADP is a mechanism that describes the scattering caused by the interaction between carriers and phonons (quanta of lattice vibrations). The larger the elastic constant of the crystal, the more difficult it is for the crystal to deform, and the weaker the ADP effect; the smaller the effective mass of the carriers, the easier it is for the carriers to be affected by lattice vibrations, and thus the stronger the ADP effect. Its matrix elements are as follows:

[0076]

[0077] PIE is a physical phenomenon in piezoelectric materials where an electric field is induced by stress or strain, and then scatters carriers (such as electrons or holes). The stronger the electric field generated by the crystal under stress, the stronger the piezoelectric scattering. Under high stress or high electric field conditions, piezoelectric scattering will significantly reduce the carrier mobility, thereby affecting the electrical conductivity and thermoelectric properties of the material. Its matrix elements are shown in the following formula:

[0078]

[0079] POP is a scattering phenomenon related to optical phonons that occurs when particles such as light or electrons interact with a polar crystal. As the temperature increases, the number of phonons in the crystal increases, and the intensity of polar optical phonon scattering also increases accordingly. The higher the energy of the incident particles, the greater the probability of interaction with optical phonons, and the more obvious the scattering phenomenon. Its matrix elements are shown in the following formula:

[0080]

[0081] IMP is a physical phenomenon widely present in semiconductor materials, which involves the interaction between carriers (such as electrons or holes) and ionized impurities. The higher the impurity concentration, the greater the probability of ionized impurity scattering. On the one hand, as the temperature increases, the ionization energy of impurity atoms decreases, making it easier to ionize; on the other hand, the thermal motion of carriers intensifies at high temperatures, which may also lead to an increase in the scattering probability. However, it should be noted that when the temperature is very high, other scattering mechanisms such as lattice vibration scattering may become more significant, thus masking the influence of ionized impurity scattering. Different types of carriers are affected differently by ionized impurities. Its matrix elements are shown in the following formula:

[0082]

[0083] Please refer to Figure 2 , Figure 2 for the schematic diagram of the variation of the total mobility and component mobilities of the Perfect structure, three oxygen defect structures (VO1, VO2, and VO3), and the passivated structure VOP of a-HfO2 / Si with the defect concentration at 300K.

[0084] Among them, ADP: acoustic deformation potential; IMP: ionized impurity; PIE: piezoelectric; POP: polar optical phonon; ND, defect concentration: defect concentration.

[0085] From Figure 2 It can be seen that the mobilities of the five structures basically do not change at low defect concentrations, but start to decline at high defect concentrations. The isotropic average mobilities of the five structures at low and medium defect concentrations are not low, which means that the carrier transport behavior is typical band transport. V O1 The change in mobility relative to the Perfect structure is small because V O1 does not involve bonding with Si and has the least impact on the structure. Comparing V O2 , V O3 Two types of sites participating in interface bonding, the appearance of O vacancies breaks the bonding between Si and HfO2, so V O2 and V O3 show a more obvious decrease in carrier mobility compared to the perfect structure. However, this performance degradation caused by interface defects improves after H passivation. The carrier mobility of V OP shows a significant increase compared to V O2 . Under n-type doping, carriers in V O2 are difficult to migrate, while the average mobility of V OP has approached the mobility of the perfect structure. Ionized impurity scattering IMP decreases with the increase in defect concentration. At higher defect concentrations, the transport of Perfect and V O1 , V O3 is dominated by the acoustic deformation potential ADP. Phonon scattering is one of the main factors affecting carrier mobility. However, the phonon scattering effect of V O2 is not serious, and H passivation alleviates this phenomenon.

[0086] Finally, the H passivation process in the present invention is to construct a new V OP structure in Matrial Studio, so that the oxygen vacancies are filled by newly formed Si-H, Hf-H, and O-H bonds. Then, structure optimization is performed in VASP to obtain the required V OP structure. Please refer to Figure 3 , Figure 3 is the schematic diagram of the interface structure after adding O vacancies in the present invention. Figure 3 In (a) of , it is the structure V O2 after passivating the oxygen vacancies of V OP with H atoms. (b) is the energy band of the V OP structure. (c) is the density of states of the V OP structure. (d) is the density of states of the V O2 structure.

[0087] Please refer to Figure 4 , Figure 4 which is a schematic diagram of the operation of the hardware device according to an embodiment of the present invention. The hardware device specifically includes: an amorphous HfO2Si interface modification device 401, a processor 402, and a storage medium 403.

[0088] An amorphous HfO2Si interface modification device 401: The amorphous HfO2Si interface modification device 401 implements the amorphous HfO2Si interface modification method.

[0089] A processor 402: The processor 402 loads and executes the instructions and data in the storage medium 403 to implement the amorphous HfO2Si interface modification method.

[0090] A storage medium 403: The storage medium 403 stores instructions and data; the storage medium 403 is used to implement the amorphous HfO2Si interface modification method.

[0091] The beneficial effects of the present invention are: A specific passivation scheme is proposed. This scheme is not just a conventional application of hydrogen passivation, but optimizes the special passivation requirements for oxygen vacancies on the HfO / Si interface, and verifies its effectiveness and feasibility through experimental data.

[0092] The H passivation scheme proposed by the present invention has clear operation steps and detailed parameter adjustments, enabling the method to achieve an ideal passivation effect in the HfO / Si interface. By comparing the experimental results, the present invention can effectively reduce interface defects, improve electron transport efficiency, and significantly improve the stability of the device. Therefore, this scheme not only has guiding significance in theory, but also has high feasibility and practical application value in actual operation.

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for modifying the interface of an amorphous HFO2Si, characterized in that: include: S1, build amorphous HFO2Si interface; S2, analyze the interface bond strength and electron gain and loss information of the constructed structure through plane average differential charge density; S3. Select the first, second and third positions in the constructed structure interface and introduce V O1 、V O2 、V O3 Three types of O vacancy defects, three different O vacancies have different bonding at the interface; S4. Analyze the effects of defect bands of three different defect structures on the electrical properties of semiconductor materials, and select the O vacancy defect with better influence to be introduced; S5, H is introduced to passivate the dangling bonds at the O vacancy defect of the better introduced position, and structure V is obtained op .

2. The method for modifying the interface of an amorphous HFO2Si according to claim 1, characterized in that: The Si-O bond length at the amorphous HFO2Si interface in step S1 is The Si-Hf bond length is 3. The method for modifying the interface of an amorphous HFO2Si according to claim 1, characterized in that: The calculation formula of the overall plane average differential charge in step S2 is as follows: Where L x , L y are the dimensions in the plane direction respectively; ρ1 and ρ0 represent the charge density of different systems or the charge density of a unified system in different states. ρ1 represents the charge density after the overall structure is optimized, and ρ0 represents the spherically symmetric charge density of each atom that makes up the overall structure in a free state, also called the deformed charge density.

4. The method for modifying the interface of an amorphous HFO2Si according to claim 1, characterized in that: The analysis of the electronic gain and loss information in step S2 is specifically as follows: When the overall plane average differential charge is positive, each atom at the interface dissipates electrons, otherwise it accumulates electrons.

5. The method for modifying the interface of an amorphous HFO2Si according to claim 1, characterized in that: The analysis of the interface bond strength in step S2 is specifically as follows: when the interface is characterized by an i-type band structure, the lowest point of the conduction band of one semiconductor is lower than the lowest point of the conduction band of another semiconductor, and its highest point of the valence band is also higher than the highest point of the valence band of another semiconductor; when the interface is characterized by a ii-type band structure, the lowest point of the conduction band of one semiconductor is lower than the lowest point of the conduction band of another semiconductor, but its highest point of the valence band is lower than the highest point of the valence band of another semiconductor. Different types of band structure characteristics reflect the strength of the bond.

6. The method for modifying the interface of an amorphous HFO2Si according to claim 5, characterized in that: In step S3, the distances between the three O vacancies and the Si interface are different, and the difference between the three O vacancies distances exceeds a preset value.

7. The method for modifying the interface of an amorphous HFO2Si according to claim 6, characterized in that: V o1 The O vacancies in the structure are far away from the interface and close to the HFO2 region, and do not participate in the interface bonding; V O2 With V O3 The oxygen vacancies in the structure are close to the interface, affecting the formation of Hf-O and Si-O bonds.

8. The method for modifying the interface of an amorphous HFO2Si according to claim 7, characterized in that: In step S5, select V O2 structure, passivated with H to eliminate the dangling bonds of the O vacancy and generate V OP structure.

9. A storage medium, characterized in that: The storage medium stores instructions and data for implementing the amorphous HFO2Si interface modification method according to any one of claims 1 to 8.

10. An amorphous HFO2Si interface modification device, characterized in that: include: Processor and storage medium; the processor loads and executes instructions and data in the storage medium to implement the amorphous HFO2Si interface modification method described in any one of claims 1 to 8.

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