Tantalum-based nitride functional layer and method for manufacturing the same

Abstract

This application discloses a tantalum-based nitride functional layer and its preparation method, relating to the field of semiconductor thin film technology. The preparation method of the tantalum-based nitride functional layer includes: depositing a tantalum-based nitride thin film on a substrate as a base; placing the substrate in a vacuum reaction chamber and introducing a precursor into the vacuum reaction chamber, wherein the precursor pressure in the reaction chamber is 1×10⁻⁶. ‑ ³-5×10 ‑ The resistivity is between 3 Pa; the electron beam scans the surface of the substrate in a planar scanning manner. Under the action of the electron beam, the precursor reacts with the surface of the tantalum-based nitride film to form a composite passivation layer. The composite passivation layer and the unreacted tantalum-based nitride film constitute the tantalum-based nitride functional layer, wherein the thickness of the composite passivation layer is between 0.5 and 3 nm. This tantalum-based nitride functional layer and its preparation method can suppress the spontaneous etching of the tantalum-based nitride film without increasing the resistivity, and are easy to control.

Description

Technical Field

[0001] This application relates to the field of semiconductor thin film technology, and more specifically, to a tantalum-based nitride functional layer and its preparation method. Background Technology

[0002] Tantalum-based nitrides (such as TaN) are widely used in core applications such as electrode materials for semiconductor devices, diffusion barrier layers in copper interconnect processes, and protective coatings for microelectromechanical systems (MEMS) devices due to their excellent overall performance. However, in the actual manufacturing processes of semiconductor devices, especially in critical steps such as etching and cleaning, tantalum-based nitride films are inevitably exposed to corrosive environments containing fluorine or chlorine species. In such environments, the Ta atoms in TaN materials react with the F atoms... - Cl - When corrosive ions undergo a thermodynamically spontaneous chemical reaction, volatile tantalum pentafluoride or tantalum pentachloride are generated. These reaction products rapidly detach from the material surface, leading to material loss on the TaN film surface. This unexpected material loss not only causes electrode failure and abnormally high contact resistance in interconnect structures, but also disrupts the integrity of the diffusion barrier layer, triggering copper atom diffusion into the silicon substrate, ultimately severely impacting the yield and long-term reliability of semiconductor devices. To address the spontaneous etching problem of tantalum-based nitrides, existing technologies have developed two main approaches: The first is surface oxidation passivation. This method involves growing a dense tantalum pentoxide film in situ on the TaN film surface through high-temperature oxidation or plasma oxidation. Using Ta₂O₅ as a physical barrier layer prevents corrosive ions from directly contacting the substrate TaN, thereby suppressing the spontaneous etching reaction. The second approach is multi-element doping. This method involves doping the TaN lattice with third-element elements such as Ti, Si, and Al to form multi-element nitride solid solutions such as TaTiN, TaSiN, and TaAlN. The introduction of doping elements aims to change the lattice structure parameters and surface electronic state distribution of TaN, reduce the chemical activity of Ta atoms, and improve the overall corrosion resistance of the material.

[0003] While the aforementioned existing technologies have improved the corrosion resistance of TaN to some extent, the first method produces a relatively thick Ta₂O₅ layer, and Ta₂O₅ is a typical insulating material with a room temperature resistivity exceeding 10¹² Ω·cm. Although the oxide layer can effectively block corrosion, its introduction significantly increases the surface contact resistance of the TaN electrode. The second method has an extremely narrow performance tuning window, making it difficult to balance conductivity and corrosion resistance. The content of doping elements is strongly coupled with the electrical and chemical properties of the material, often resulting in trade-offs. Taking the widely used TaSiN as an example, as the Si content increases, although the introduction of Si-N bonds improves the resistance to fluorine etching, it also disrupts the original conductive network, leading to a sharp increase in resistivity. Summary of the Invention

[0004] The purpose of this application is to provide a tantalum-based nitride functional layer and its preparation method, which can suppress spontaneous etching of tantalum-based nitride films without increasing resistivity and is easy to control.

[0005] The embodiments of this application are implemented as follows: A first aspect of this application provides a method for preparing a tantalum-based nitride functional layer, comprising: depositing a tantalum-based nitride thin film on a substrate as a base; placing the base in a vacuum reaction chamber and introducing a precursor into the vacuum reaction chamber, wherein the precursor pressure in the reaction chamber is 1×10⁻⁶. - ³-5×10 - The thickness is between 3 Pa; the electron beam scans the surface of the substrate in a surface scanning manner, and the precursor reacts with the surface of the tantalum-based nitride film under the action of the electron beam to form a composite passivation layer. The composite passivation layer and the unreacted tantalum-based nitride film constitute the tantalum-based nitride functional layer, wherein the thickness of the composite passivation layer is between 0.5-3 nm.

[0006] As one possible implementation, the electron beam scanning time of the substrate surface is 1-5 minutes.

[0007] As one possible implementation, a tantalum-based nitride film is formed on a substrate by physical vapor deposition or chemical vapor deposition, wherein the temperature of the substrate is 250°C-350°C, the working pressure is between 0.5-1.5 Pa when using physical vapor deposition, and between 10-50 Pa when using chemical vapor deposition.

[0008] As one possible implementation, the tantalum-based nitride film has a density greater than 98% and a resistivity less than 30 μΩ·cm.

[0009] As one possible implementation method, the electron beam accelerating voltage is between 0.2-2kV, the beam current is between 20pA-800pA, and the scanning rate is between 5-15μm / s.

[0010] As one possible implementation method, the electron beam accelerating voltage is between 0.5-1.5kV, and the beam current is between 100pA-500pA.

[0011] As one possible implementation method, the precursor is one or a combination of multiple of NO2, H2O, O2, O3, tetraethoxysilane, hexamethyldisiloxane, and aluminum ethoxide.

[0012] As one possible implementation, the precursor is a mixture of O3 and tetraethoxysilane, wherein the volume ratio of O3 to tetraethoxysilane is between 1:2 and 1:5.

[0013] As one possible implementation, the precursor includes O3 and tetraethoxysilane. After O3 is introduced into the vacuum reaction chamber, tetraethoxysilane is then introduced into the vacuum reaction chamber. The flow rate ratio of O3 to tetraethoxysilane is between 1:2 and 1:5.

[0014] As one possible implementation, after the electron beam scans the surface of the substrate in a surface scanning manner, and the precursor reacts with the surface of the tantalum-based nitride film under the action of the electron beam to form a composite passivation layer, the method for preparing the tantalum-based nitride functional layer further includes: introducing an inert gas into a vacuum reaction chamber at a rate of 5-100 sccm for 30-60 seconds, so that the vacuum degree of the vacuum reaction chamber is less than 5 × 10⁻⁶. -4 Pa.

[0015] A second aspect of this application provides a tantalum-based nitride functional layer, which is prepared by the above-described method for preparing a tantalum-based nitride functional layer, and includes a tantalum-based nitride thin film and a composite passivation layer disposed on a substrate.

[0016] The beneficial effects of the embodiments of this application include: The method for preparing a tantalum-based nitride functional layer provided in this application includes depositing a tantalum-based nitride thin film on a substrate as a base; placing the substrate in a vacuum reaction chamber and introducing a precursor into the vacuum reaction chamber, wherein the precursor pressure in the reaction chamber is 1×10⁻⁶. - ³-5×10 -Between 3 Pa; the electron beam scans the substrate surface in a planar scanning manner. Under the action of the electron beam, the precursor reacts with the surface of the tantalum-based nitride film to form a composite passivation layer. The composite passivation layer and the unreacted tantalum-based nitride film constitute the tantalum-based nitride functional layer. The thickness of the composite passivation layer is between 0.5-3 nm. The thickness is controlled within the range of 0.5-3 nm, resulting in an extremely thin passivation layer, only a few atomic layers to a few nanometers. When the passivation layer thickness is controlled within 0.5-3 nm, electrons can pass through the potential barrier through the quantum tunneling effect, so that the overall surface contact resistance hardly increases. The reaction only occurs in the outermost layer, without changing the crystal structure and conductive network of the underlying tantalum-based nitride film, thus preserving the high conductivity of the substrate. The electron beam-induced reaction forms dense Ta-X (X is the precursor element) bonds on the surface of the tantalum-based nitride film, filling the lattice defects and dangling bonds on the TaN surface. These defects are often the starting points for spontaneous etching, thus effectively suppressing the spontaneous etching of the tantalum-based nitride film. Furthermore, the embodiments of this application employ electron beam scanning, where the composition of the composite passivation layer is determined by the precursor and electron beam energy, independent of the substrate composition. This decouples the control of electrical and chemical properties, providing a wider process window and enabling better control of the reaction compared to existing technologies. In summary, the method for preparing the tantalum-based nitride functional layer of this application can suppress spontaneous etching of the tantalum-based nitride film without increasing resistivity, and is easily controllable. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a method for preparing a tantalum-based nitride functional layer provided in this application embodiment; Figure 2 SEM image of a cross-section of a tantalum-based nitride functional layer provided in an embodiment of this application; Figure 3 A comparison of the corrosion rates of the tantalum-based nitride thin film and the tantalum-based nitride functional layer provided in the embodiments of this application in 5% HF solution.

[0019] Icons: 100 - Substrate 110; 110 - Tantalum-based nitride film; 120 - Composite passivation layer. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this application, not all embodiments. Similar reference numerals and letters in the following drawings indicate similar items. Once an item is defined in one drawing, it does not need to be further defined in other drawings.

[0021] The terms “center,” “upper,” “lower,” “left,” “right,” “vertical,” “horizontal,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product is usually placed in when in use. They are used only for the convenience of describing this application and simplifying the description, and should not be construed as limiting this application.

[0022] This application provides a method for preparing a tantalum-based nitride functional layer, such as... Figure 1 As shown, it includes: S100: A tantalum-based nitride film 110 is deposited on a substrate 110 as a substrate; A tantalum-based nitride thin film 110 is prepared on a substrate 110. The tantalum-based nitride thin film 110 is the main body of the tantalum-based nitride functional layer, responsible for providing the main conductive path and mechanical support. The specific material of the substrate 110 is not limited in this application embodiment; it can be a single-crystal silicon wafer or a heterogeneous substrate such as glass, sapphire, or SiC.

[0023] The tantalum-based nitride film 110 can be either TaN or Ta-Si-N.

[0024] S200: The substrate is placed in a vacuum reaction chamber and a precursor is introduced into the chamber, wherein the pressure of the precursor in the reaction chamber is 1×10⁻⁶. - ³-5×10 - Between ³Pa; Specifically, the substrate is placed in a vacuum chamber, a specific precursor is introduced, and the pressure is strictly controlled at 1×10⁻⁶. - ³-5×10 - The pressure range is extremely low, exceeding 3 Pa. This pressure range falls within the transition region from high vacuum to ultra-high vacuum. Extremely low pressure means that the mean free path of gas molecules is very long, and precursor molecules within the cavity primarily move in straight lines, resulting in a low probability of collisions. This ensures that the precursor only reacts when subsequently bombarded directly by an electron beam or adsorbed onto the stimulated surface, avoiding gas-phase nucleation (i.e., particle formation in space), thus guaranteeing the surface selectivity of the reaction and the precision of ultrathin layer control.

[0025] S300: The electron beam scans the surface of the substrate in a surface scanning manner. The precursor reacts with the surface of the tantalum-based nitride film 110 under the action of the electron beam to form a composite passivation layer 120. The composite passivation layer 120 and the unreacted tantalum-based nitride film 110 constitute a tantalum-based nitride functional layer. The thickness of the composite passivation layer 120 is between 0.5-3 nm.

[0026] High-energy electrons carried by an electron beam bombard precursor molecules adsorbed on the TaN surface, generating localized high-energy excited states, such as dissociation of the adsorbed precursors. This energy injection induces a chemical reaction between the precursors and Ta atoms on the TaN surface, forming a composite passivation layer 120.

[0027] The use of surface scanning ensures the uniformity of the scanning process, guarantees a uniform passivation layer thickness on the large-area substrate 110, and avoids localized corrosion weaknesses. The composite passivation layer 120 refers to a material that is not just a simple oxide, but may contain nitrides, carbides, or complex compounds formed by other elements in the precursor and Ta.

[0028] The thickness is controlled between 0.5-3 nm, resulting in an extremely thin passivation layer, only a few atomic layers to a few nanometers thick. When the passivation layer thickness is controlled between 0.5-3 nm, electrons can pass through the potential barrier through quantum tunneling. For such a thin insulating or semi-insulating layer, the increase in its equivalent contact resistance is negligible, far below the predicted value of macroscopic Ohm's law, resulting in almost no increase in the overall surface contact resistance. The reaction only occurs in the outermost layer, without changing the crystal structure and conductive network of the underlying tantalum-based nitride film 110, thus preserving the high conductivity of the substrate. The electron beam-induced reaction forms dense Ta-X (X is the precursor element) bonds on the surface of the tantalum-based nitride film 110, filling lattice defects and dangling bonds on the TaN surface. These defects are often the starting points for spontaneous etching, thus effectively suppressing the spontaneous etching of the tantalum-based nitride film 110. Figure 2 As shown, the corrosion rate of the tantalum-based nitride film 110 with the composite passivation layer 120 decreases rapidly. Furthermore, this embodiment employs electron beam scanning, where the composition of the composite passivation layer 120 is determined by the precursor and electron beam energy, independent of the substrate composition. This decouples the control of electrical and chemical properties, providing a wider process window and better control over the reaction compared to existing technologies. In summary, the method for preparing the tantalum-based nitride functional layer in this embodiment can suppress spontaneous etching of the tantalum-based nitride film 110 without increasing resistivity, and is easily controllable.

[0029] In other words, this embodiment uses an ultrathin composite passivation layer 120 instead of a thick insulating layer. The composite passivation layer 120 acts as a tunneling layer, maintaining excellent corrosion resistance while avoiding a significant increase in contact resistance. Replacing bulk doping with independent surface modification breaks the strong coupling between the conductive network and the corrosion-resistant components, broadens the performance control window, and avoids sacrificing one aspect for another.

[0030] In addition, electron beam induced reactions are usually carried out at room temperature or low temperature. The reaction temperature depends on the specific precursor, but high-temperature annealing is not required, which avoids thin film stress changes, grain coarsening or thermal mismatch with substrate 110 that may be caused by high-temperature processes.

[0031] It should be noted that tantalonitrides can be TaN, or multi-component tantalum-based nitrides such as TaTiN and TaAlN.

[0032] Optionally, the electron beam scanning time of the substrate surface is 1-5 minutes.

[0033] If the electron beam scanning time is too short, the precursor molecules will not dissociate and deposit sufficiently under the electron beam, failing to form a continuous and dense capping layer on the surface of the tantalum-based nitride film 110. This results in pinholes or island-like growth in the passivation layer, which cannot effectively block corrosive media. Conversely, if the time is too long, the passivation layer thickness will exceed the critical value of 3 nm. Once this thickness is exceeded, the quantum tunneling effect will be significantly weakened, the contact resistance will increase exponentially, and it may also lead to increased surface roughness or unnecessary accumulation of by-reaction products. Based on the above reasons, the electron beam scanning time in this embodiment is set to 1-5 min.

[0034] The electron beam scanning time in this embodiment ensures the thickness of the target composite passivation layer 120.

[0035] As one feasible method, a tantalum-based nitride film 110 is formed on a substrate by physical vapor deposition or chemical vapor deposition, wherein the temperature of the substrate is 250℃-350℃, the working pressure is between 0.5-1.5 Pa when using physical vapor deposition, and the working pressure is between 10-50 Pa when using chemical vapor deposition.

[0036] The substrate temperature is between 250℃ and 350℃, which falls within the medium-low temperature deposition range. This temperature is higher than room temperature to ensure that atoms have a certain surface mobility to form a dense lattice tantalum-based nitride film 110; yet it is also much lower than traditional high-temperature processes to avoid thermal damage to the underlying substrate 110.

[0037] Specifically, tantalum nitride exists in multiple crystal phases. Among them, the tetragonal β-Ta is metastable and has extremely high resistivity, while the cubic α-Ta is stable and has low resistivity. When the substrate temperature is below 250℃, the atomic mobility is insufficient, which easily leads to the formation of an amorphous or high-resistivity β-Ta phase, resulting in excessively high substrate resistivity that cannot meet electrode requirements. When the substrate temperature is between 250℃ and 350℃, sufficient thermal energy is provided to promote Ta atom rearrangement, tending to form a low-resistivity α-Ta phase or a mixed phase. At the same time, it promotes uniform solid solution of nitrogen atoms, forming a TaN thin film with a suitable stoichiometric ratio, achieving low resistivity. When the substrate temperature is above 350℃, although the crystallinity is better, it may cause excessively coarse grains, increasing surface roughness. Furthermore, the high temperature may cause diffusion or decomposition of the substrate 110 material, compromising device integrity.

[0038] When using physical vapor deposition (PVD), if the gas pressure is below 0.5 Pa, the particle energy is too high, resulting in a strong bombardment effect. Although the film is dense, it is prone to high compressive stress, leading to film peeling or warping, poor step coverage, and a tendency to produce shading effects. If the gas pressure is above 1.5 Pa, the particle energy loss is too great, resulting in insufficient kinetic energy when reaching the substrate (110). This leads to a loose and porous film with significant columnar crystal growth, and the pores become rapid channels for corrosive media. However, when the gas pressure is between 0.5 and 1.5 Pa, the particle energy and scattering effect are balanced, resulting in a dense, low-stress, and strongly adherent film, providing a smooth and pore-free TaN film for subsequent ultrathin passivation layers.

[0039] When using chemical vapor deposition (CVD), the working pressure is between 10-50 Pa. Within this pressure range, the surface adsorption of precursor molecules and the reaction rate reach equilibrium. Higher pressure increases the concentration of gas molecules, which, combined with surface diffusion, allows reactants to penetrate deep into the trench bottom and sidewalls, achieving excellent step coverage and ensuring consistent conductivity and corrosion resistance throughout the three-dimensional electrode structure. This avoids the problems of incomplete reaction under extremely low pressure or gas-phase nucleation (generating powder particles) under extremely high pressure, thus guaranteeing film purity.

[0040] Optionally, the tantalum-based nitride film 110 has a density greater than 98% and a resistivity less than 30 μΩ·cm.

[0041] A density greater than 98% means that the actual density of the tantalum-based nitride film 110 reaches more than 98% of its theoretical crystal density. This implies that the porosity inside the tantalum-based nitride film 110 is extremely low, the lattice arrangement is highly compact, and there are almost no micropores, voids, or intergranular gaps. The high density eliminates diffusion channels. The diffusion of corrosive media (such as fluoride ions) in the film mainly occurs through grain boundaries, micropores, and intergranular gaps. A density >98% means that these diffusion channels are essentially cut off. Spontaneous corrosion usually begins at surface defects or internal pores, where corrosive media accumulate and penetrate downwards. The high density eliminates these nucleation sites, making it difficult for the corrosion reaction to initiate, thus inhibiting spontaneous corrosion.

[0042] Specifically, at a moderate temperature of 250-350℃, the deposited atoms have sufficient surface migration energy to find the lowest energy lattice position for accumulation, avoiding the shadowing effect and loose columnar crystal structure common in low-temperature deposition, thus forming a dense structure similar to a single crystal.

[0043] Among them, the tantalum-based nitride thin film 110, with a resistivity of less than 30 μΩ·cm, provides an extremely low background resistance for the tantalum-based nitride functional layer. Even though the surface passivation layer introduces a small increase in contact resistance, the total resistance remains at an extremely low level, fully meeting the low impedance requirements of advanced interconnects and electrodes.

[0044] As a feasible approach, the electron beam accelerating voltage is between 0.2 and 2 kV, the beam current is between 20 pA and 800 pA, and the scanning rate is between 5 and 15 μm / s.

[0045] The electron beam accelerating voltage is set between 0.2-2kV, strictly limiting the electron penetration depth to within a few atomic layers on the surface. This ensures the thickness of the composite passivation layer 120 while completely unaffecting the crystal structure and grain boundary state of the underlying tantalum-based nitride film 110. The beam current is set between 20pA-800pA, ensuring sufficient energy to excite the precursor reaction while avoiding heat accumulation and charge buildup effects caused by high current. The scan rate is set between 5-15μm / s, ensuring a moderate electron dose per unit area, resulting in a complete and uniform reaction, and avoiding incomplete reactions due to underexposure or substrate damage due to overexposure.

[0046] Optionally, the electron beam accelerating voltage is between 0.5 and 1.5 kV, and the beam current is between 100 pA and 500 pA.

[0047] By using an electron beam accelerating voltage between 0.5 and 1.5 kV and a beam current between 100 pA and 500 pA, higher film quality and optimal process stability can be achieved.

[0048] It is understandable that the acceleration voltage, beam current, and scanning rate of the electron beam work together to achieve a dense, relatively thin composite passivation layer 120.

[0049] As one feasible approach, the precursor is one or a combination of more of the following: NO2, H2O, O2, O3, tetraethoxysilane (TEOS), hexamethyldisiloxane (HMDSO), and aluminum ethoxide.

[0050] NO2, H2O, O2, and O3 provide oxygen or nitrogen sources, which combine with tantalum atoms on the TaN film surface to form tantalum oxide (Ta2O5), tantalum oxynitride (TaON), or tantalum hydroxide in situ on the TaN film surface. These form dense inorganic barrier layers. Tetraethoxysilane and hexamethyldisiloxane provide silicon, oxygen, and carbon sources, which combine with tantalum atoms on the TaN film surface to form silica-like, siloxane-like, or carbon-doped silica films in situ on the TaN film surface. Among them, TEOS is a representative inorganic silicon source with high film purity; HMDSO is an organosilicon source with fast film formation speed and certain hydrophobicity. Aluminum ethoxide provides aluminum and oxygen sources to form aluminum oxide (Al2O3) and tantalum oxide (Ta2O5). Among them, Al2O3 is an excellent diffusion barrier layer with extremely high density and chemical stability.

[0051] The Ta2O5 / TaON layer is homologous to the TaN film, exhibiting extremely high lattice matching and no interfacial stress. It perfectly seals the dangling bonds on the TaN surface, cutting off the corrosion initiation point at its source. The Al2O3 layer possesses an extremely low ion diffusion coefficient, effectively blocking F... - Cl - Osmosis, especially Cl - Infiltration; SiOx / SiOC layer: forms a continuous network structure, filling microscopic defects.

[0052] A wide range of precursor sources are available, and the precursors are all gases commonly used in the semiconductor industry, which are inexpensive, have a stable supply, and do not require special customization. Those skilled in the art can select different types and proportions of precursors according to the corrosive environment.

[0053] Optionally, the precursor is a mixture of O3 and tetraethoxysilane, wherein the volume ratio of O3 to tetraethoxysilane is between 1:2 and 1:5.

[0054] A mixture of O3 and tetraethoxysilane is used as a precursor, with O3 acting as the oxygen source, to bond with tantalum atoms on the TaN film surface, generating tantalum oxide in situ on the TaN film surface. Tetraethoxysilane acts as the silicon source, generating silicon oxide in situ on the TaN film surface, forming a composite passivation layer 120 with tantalum oxide and silicon oxide. Under electron beam induction, the Si-O bonds in the newly generated SiO2 and the newly generated Ta-O bonds in the substrate undergo a condensation reaction at the interface, forming a strong Si-O-Ta chemical bridge. This means that the SiO2 layer is no longer physically adsorbed on the TaN film, but rather chemically bonded to the tantalum oxide transition layer, achieving a truly integrated composite structure.

[0055] As one feasible approach, the precursors include O3 and tetraethoxysilane. O3 is introduced into the vacuum reaction chamber before tetraethoxysilane is introduced into the vacuum reaction chamber, with the flow rate ratio of O3 to tetraethoxysilane between 1:2 and 1:5.

[0056] After introducing O3, tetraethoxysilane is then introduced, resulting in the formation of a tantalum oxide layer followed by a silicon oxide layer. The tantalum oxide lattice matches TaN very well, exhibiting no interfacial stress, but when present alone, it may contain oxygen vacancies, leading to slightly lower corrosion resistance. The silicon oxide amorphous network is extremely dense, exhibiting excellent corrosion resistance, but direct growth on TaN may result in microcracks due to lattice mismatch. In the composite passivation layer 120 of this embodiment, tantalum oxide acts as a buffer layer to eliminate mismatch stress, while silicon oxide acts as a capping layer to fill the vacancies in TaOx. The combination of these two layers enhances the suppression of spontaneous etching.

[0057] Optionally, after the electron beam scans the surface of the substrate in a surface scanning manner, and the precursor reacts with the surface of the tantalum-based nitride film 110 under the action of the electron beam to form a composite passivation layer 120, the method for preparing the tantalum-based nitride functional layer further includes: S400: Inert gas is introduced into the vacuum reaction chamber at a rate of 5-100 sccm for 30-60 seconds, so that the vacuum degree of the vacuum reaction chamber is less than 5 × 10⁻⁶. -4 Pa.

[0058] After the formation of the composite passivation layer 120, but before vacuum breaking, the surface of the newly formed composite passivation layer 120 may still contain incompletely reacted dangling bonds or adsorbed active free radicals. These dangling bonds or adsorbed active free radicals react with substances in the air, not only introducing impurities but also changing the dielectric constant and even triggering subsequent electrochemical corrosion. In this embodiment, an inert gas is used to passivate the surface. The inert gas rapidly occupies the space around these active sites. Although it does not chemically bond, it prevents the adsorption of harmful substances by physically isolating and removing the active source, thus improving the stability of the tantalum-based nitride functional layer. The inert gas does not chemically react with the newly formed SiO2 / TaOx layer; it only acts as a physical carrier.

[0059] In addition, unreacted TEOS molecules, O2 produced by O3 decomposition, and reaction byproducts may be physically adsorbed on the walls of the vacuum reaction chamber and the surface of the tantalum-based nitride functional layer. If these residues are not removed, they will volatilize and re-condense on the film surface after the vacuum is broken, forming an organic contaminant layer that affects subsequent photolithography or packaging processes. An airflow of 5-100 sccm generates a laminar flow scouring effect, forcibly stripping the weakly bound molecules adsorbed on the surface and carrying them out of the chamber. 30-60 seconds is sufficient to replace at least 5-10 chamber volumes, ensuring that the residual concentration is reduced to the ppb level.

[0060] In a second aspect, this application also provides a tantalum-based nitride functional layer, prepared using the above-described method for preparing tantalum-based nitride functional layers, such as... Figure 3 As shown, it includes a tantalum-based nitride film 110 and a composite passivation layer 120 disposed on a substrate 110. The structure and beneficial effects of this tantalum-based nitride functional layer have been described in detail in the foregoing embodiments, and therefore will not be repeated here.

[0061] The above description is merely an optional embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0062] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.

Claims

1. A method for preparing a tantalum-based nitride functional layer, characterized in that, include: A tantalum-based nitride film is deposited on a substrate as a base. The substrate is placed inside a vacuum reaction chamber, and a precursor is introduced into the chamber, wherein the pressure of the precursor within the chamber is 1 × 10⁻⁶. - ³-5×10 - Between ³Pa; An electron beam scans the surface of the substrate in a surface scanning manner. The precursor reacts with the surface of the tantalum-based nitride film under the action of the electron beam to form a composite passivation layer. The composite passivation layer and the unreacted tantalum-based nitride film constitute a tantalum-based nitride functional layer. The thickness of the composite passivation layer is between 0.5-3 nm.

2. The method for preparing the tantalum-based nitride functional layer according to claim 1, characterized in that, The electron beam scans the substrate surface for 1-5 minutes.

3. The method for preparing the tantalum-based nitride functional layer according to claim 1, characterized in that, A tantalum-based nitride film is formed on a substrate by physical vapor deposition or chemical vapor deposition, wherein the temperature of the substrate is 250℃-350℃, the working gas pressure is between 0.5-1.5 Pa when using physical vapor deposition, and between 10-50 Pa when using chemical vapor deposition.

4. The method for preparing the tantalum-based nitride functional layer according to claim 3, characterized in that, The density of the tantalum-based nitride film is greater than 98%, and the resistivity is less than 30 μΩ·cm.

5. The method for preparing the tantalum-based nitride functional layer according to claim 1, characterized in that, The electron beam accelerating voltage is between 0.2-2kV, the beam current is between 20pA-800pA, and the scanning rate is between 5-15μm / s.

6. The method for preparing the tantalum-based nitride functional layer according to claim 5, characterized in that, The electron beam accelerating voltage is between 0.5 and 1.5 kV, and the beam current is between 100 pA and 500 pA.

7. The method for preparing the tantalum-based nitride functional layer according to claim 1, characterized in that, The precursor is one or a combination of multiple of NO2, H2O, O2, O3, tetraethoxysilane, hexamethyldisiloxane, and aluminum ethoxide.

8. The method for preparing the tantalum-based nitride functional layer according to claim 7, characterized in that, The precursor is a mixture of O3 and tetraethoxysilane, wherein the volume ratio of O3 to tetraethoxysilane is between 1:2 and 1:

5.

9. The method for preparing the tantalum-based nitride functional layer according to claim 7, characterized in that, The precursor includes O3 and tetraethoxysilane. After O3 is introduced into the vacuum reaction chamber, tetraethoxysilane is introduced into the vacuum reaction chamber. The flow rate ratio of O3 to tetraethoxysilane is between 1:2 and 1:

5.

10. The method for preparing the tantalum-based nitride functional layer according to claim 1, characterized in that, After the electron beam scans the surface of the substrate in a surface scanning manner, and the precursor reacts with the surface of the tantalum-based nitride film under the action of the electron beam to form a composite passivation layer, the method further includes: An inert gas is introduced into the vacuum reaction chamber at a rate of 5-100 sccm for 30-60 seconds, resulting in a vacuum level of less than 5 × 10⁻⁶. -4 Pa.

11. A tantalum-based nitride functional layer, characterized in that, It is prepared by the method of any one of claims 1-10, comprising a tantalum-based nitride thin film and a composite passivation layer disposed on a substrate.

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