Interconnection structure and preparation method thereof

Abstract

The invention discloses an interconnection structure and a preparation method thereof. The preparation method comprises the steps that a first metal layer located in a first dielectric layer is formed on a substrate; forming a second dielectric layer made of a low dielectric constant material on the first dielectric layer, and forming a through hole connected with the first metal layer on the second dielectric layer; forming an organic hydrophobic layer of a monomolecular layer on the first metal layer at the bottom of the through hole by using a gas phase self-assembly process; carrying out first treatment on the side wall of the through hole so as to improve the adhesion of the surface of the low-dielectric-constant material and the interface diffusion blocking capability; forming a tantalum layer on the side wall of the through hole, and inhibiting the tantalum layer from being formed on the organic hydrophobic layer; and removing the organic hydrophobic layer, and filling a second metal layer electrically connected with the first metal layer in the through hole within the tantalum layer. According to the invention, the proportion of the resistance value of the diffusion barrier layer in the resistance value of the whole through hole can be effectively reduced, the lower resistance value and interconnection stability are realized, and the technical requirements of advanced nodes are well met.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and in particular to an interconnect structure and a method for fabricating the same. Background Technology

[0002] Currently, for back-end logic processes, the diffusion barrier layer in copper (Cu) vias typically employs a dual-layer structure of tantalum nitride (TaN) and tantalum (Ta). TaN is used to adhere to the dielectric layer (low dielectric constant (LK) and ultra-low dielectric constant (ULK) materials for advanced nodes), while Ta is used to reduce resistance and adhere to the subsequently deposited Cu within the via. This achieves a balance between diffusion barrier capability and resistance reduction. However, with continuously shrinking linewidths, the requirements for high diffusion barrier capability, good interface affinity, low resistance, and high reliability are becoming increasingly stringent. As the technology progresses down to the next lower node, the diameter of vias continuously decreases, requiring increasingly thinner overall film thicknesses for diffusion barrier layers using a combination of TaN and Ta (the thickness of the diffusion barrier layer accounts for a larger proportion of the total Cu metal via diameter, becoming a major reason why contact resistance and RC delay are difficult to reduce). This leads to increasingly poor interfacial affinity of the diffusion barrier layer, often resulting in film pitting and peeling defects, causing low yields. Consequently, it becomes difficult to further reduce the overall film thickness of diffusion barrier layers using a combination of TaN and Ta, resulting in severe RC delay and difficulty in reducing subsequent contact resistance. Therefore, it is necessary to investigate a process method that can significantly improve the above problems. Summary of the Invention

[0003] The purpose of this application is to overcome the aforementioned problems in the prior art and to provide an interconnect structure and its fabrication method.

[0004] To achieve the above objectives, the technical solution of this application is as follows: According to a first aspect of this application, embodiments of this application provide a method for fabricating an interconnect structure, comprising: Provide substrate; A first dielectric layer is formed on the surface of the substrate, and a first metal layer located in the first dielectric layer is formed on the surface of the first dielectric layer. A second dielectric layer is formed on the surface of the first dielectric layer to cover the first metal layer, and the material of the second dielectric layer includes a low dielectric constant material; A through-hole is formed on the surface of the second dielectric layer, with its bottom surface connected to the surface of the first metal layer; Using a vapor-phase self-assembly process, a monolayer organic hydrophobic layer is selectively formed on the exposed surface of the first metal layer at the bottom of the via. The sidewalls of the via are first treated with nitrogen free radicals excited by metastable particles to improve the adhesion of the low dielectric constant material surface on the sidewalls and the ability to block interfacial diffusion. A tantalum layer is selectively formed on the sidewall after the first treatment, while the formation of the tantalum layer on the surface of the organic hydrophobic layer is inhibited. Remove the organic hydrophobic layer and fill the via within the tantalum layer with a second metal layer electrically connected to the first metal layer.

[0005] In some embodiments, by performing the first treatment, nitrogen free radicals react with the bonding bonds on the low dielectric constant material surface of the sidewall to form a nitrogen-rich surface layer, thereby blocking interfacial diffusion and optimizing surface energy, and improving the continuity and uniformity of the tantalum layer when it is directly deposited on the sidewall.

[0006] In some embodiments, the low dielectric constant material includes silicon-based low dielectric constant materials.

[0007] In some embodiments, after forming the tantalum layer, the method further includes: using hydrogen radicals excited by metastable particles to perform a second treatment on the surface of the tantalum layer to reduce the surface state density.

[0008] In some embodiments, the method further includes using hydrogen radicals excited by metastable particles to treat at least one of a third treatment and a fourth treatment on the exposed surface of the first metal layer at the bottom of the via to generate surface activity; wherein the third treatment is performed before the formation of the organic hydrophobic layer, and the fourth treatment is performed after the removal of the organic hydrophobic layer.

[0009] In some embodiments, the nitrogen free radicals are obtained by exciting nitrogen gas with helium metastable particles and filtering out charged particles therein. The helium metastable particles are obtained by exciting helium gas and filtering out charged particles therein. During the first treatment, the flow rate of helium gas is 1000 sccm to 9000 sccm, the nitrogen gas flow rate: helium gas flow rate = 1:1 to 10:1, the temperature is 50℃ to 200℃, the source power is 1W to 100W, the pressure is 10mTorr to 1000mTorr, the time is 5s to 300s, and ion filtering is turned on while the bias power is turned off.

[0010] In some embodiments, the hydrogen radicals are obtained by exciting hydrogen gas with helium metastable particles and filtering out charged particles therein. The helium metastable particles are obtained by exciting helium gas and filtering out charged particles therein. During the second treatment, argon gas is added to the hydrogen gas to adjust the concentration of the hydrogen gas. The flow rate of the helium gas is 1000 sccm to 2000 sccm, the flow rate of the mixed gas of hydrogen and argon is 0.1:1 to 2:1, the flow rate of hydrogen gas is 1:1 to 1:3, the temperature is 100℃ to 200℃, the source power is 100W to 500W, the pressure is 10mTorr to 1000mTorr, the time is 5s to 300s, and the ion filter is turned on while the bias power is turned off.

[0011] In some embodiments, the hydrogen radicals are obtained by exciting hydrogen gas with helium metastable particles and filtering out charged particles therein. The helium metastable particles are obtained by exciting helium gas and filtering out charged particles therein. When performing the third or fourth treatment, the helium flow rate is 1000 sccm to 9000 sccm, the hydrogen flow rate: helium flow rate = 1:1 to 10:1, the temperature is 50℃ to 200℃, the source power is 1W to 100W, the pressure is 10mTorr to 1000mTorr, the time is 5s to 300s, and the ion filter is turned on while the bias power is turned off.

[0012] In some embodiments, a thiol-containing organic molecule or a silicon-containing organic molecule is used as a precursor, and a diluent gas is added to form the organic hydrophobic layer.

[0013] In some embodiments, the thiol-containing organic molecule includes alkyl thiols.

[0014] In some embodiments, the silicon-containing organic molecule includes organosilanes.

[0015] In some embodiments, when performing the vapor phase self-assembly process, the temperature is 50°C to 150°C, the pressure is 100 mTorr to 10000 mTorr, and the time is 10 s to 300 s.

[0016] In some embodiments, the diluent gas includes at least one of nitrogen, hydrogen, and an inert gas.

[0017] In some embodiments, the organic hydrophobic layer is removed by thermal decomposition at a temperature of 300°C to 400°C.

[0018] According to a second aspect of this application, embodiments of this application also provide an interconnect structure obtained using the interconnect structure fabrication method provided in any of the embodiments of the first aspect above.

[0019] The embodiments of this application may have, or at least have, the following advantages: (1) By using nitrogen free radicals excited by metastable particles to perform the first treatment on the sidewall of the via, nitrogen free radicals (nitrogen atoms) can be adsorbed on the surface of the low dielectric constant material on the sidewall at low energy to form dangling bonds (which can prevent nitrogen atoms from entering the interior of the low dielectric constant material and causing the dielectric constant (k) value to increase), thus optimizing the surface state (surface energy) and enhancing the adhesion between tantalum and the sidewall surface of the low dielectric constant material. This is beneficial for the tantalum layer, which acts as a diffusion barrier layer, to form a more continuous and uniform film on the sidewall, thereby reducing the contact resistance. Furthermore, by reacting nitrogen free radicals with the bonding bonds on the surface of the low dielectric constant material on the sidewall, a dense nitrogen-rich surface layer is formed on the surface of the low dielectric constant material on the sidewall. This reduces the defect channels on the surface and improves the ability of the surface to block interfacial diffusion. It can effectively prevent the diffusion of metal (such as Cu) atoms, moisture or other impurities into the porous low dielectric constant material in subsequent processes, thus preventing the degradation of electrical properties (such as increased k value, increased leakage current, etc.). By performing the first treatment, nanoscale, uniform shallow surface modification of low dielectric constant materials is achieved, which maintains the low-k characteristics of the second dielectric layer while constructing an effective sealing barrier.

[0020] (2) By using hydrogen free radicals excited by metastable particles to perform a second treatment on the surface of the tantalum layer, the oxide layer and impurities can be removed at low energy and low temperature, the surface of the tantalum layer can be cleaned, and active hydrogen atoms can be used to combine with the cleaned Ta surface atoms to form Ta-H bonds, making the surface "hydrogen terminalized". This can effectively passivate the dangling bonds and highly active sites on the surface, reduce the surface state density, provide a more ideal nucleation surface for subsequent film deposition, help grow a denser, more uniform, and higher crystal quality film, and further reduce the contact resistance and RC delay.

[0021] (3) By selectively forming a monolayer organic hydrophobic layer on the exposed surface of the first metal layer at the bottom of the via using a vapor-phase self-assembly process, the organic hydrophobic layer can inhibit the deposition of the tantalum layer at the bottom of the via, allowing the tantalum layer to be selectively formed on the sidewall of the via. This enables the second metal layer subsequently filled in the via to be directly electrically connected to the first metal layer below, eliminating the problem of increased contact resistance caused by the deposition of a diffusion barrier layer at the bottom of the via in existing processes. This meets the requirements for lower resistance and higher reliability at advanced nodes. Furthermore, by using hydrogen free radicals excited by metastable particles to perform a third treatment on the exposed surface of the first metal layer at the bottom of the via, surface oxidation can be effectively prevented and impurities removed, and surface activity can be generated, improving the formation quality of the organic hydrophobic layer. This is beneficial for forming a dense, monolayer, hydrophobic "molecular barrier," which better promotes the selective deposition of the tantalum layer only on the sidewall.

[0022] (4) By enhancing the adhesion and interfacial diffusion barrier capabilities of the low dielectric constant material's sidewall surface, the deposition quality of the tantalum layer is improved, allowing a single tantalum layer to function as a diffusion barrier layer independently. This eliminates the need for tantalum nitride in the diffusion barrier layer (i.e., replacing the original TaN and Ta combination diffusion barrier layer with a single Ta layer diffusion barrier layer). Consequently, the total thickness of the diffusion barrier layer is reduced, effectively lowering its proportion in the overall via resistance. Furthermore, by performing a second treatment to improve the deposition quality of the second metal layer on the tantalum layer, and by preventing tantalum deposition at the bottom of the via and performing a fourth treatment to enhance the surface activity of the first metal layer, the second metal layer can achieve a high-quality direct electrical connection with the first metal layer, further reducing contact resistance. This significantly reduces the downstream contact resistance and RC delay.

[0023] The process steps in this application are highly compatible, which can enhance the adhesion of downstream metal interconnects, achieve lower resistance and interconnect stability, and well meet the technical requirements of advanced nodes.

[0024] Other advantages of this application will be described in the following detailed description. Attached Figure Description

[0025] Figure 1 This is a flowchart of a method for fabricating an interconnect structure according to a preferred embodiment of this application.

[0026] Figure 2 This is a schematic diagram of a first dielectric layer and a first metal layer formed on the surface of a substrate, according to a preferred embodiment of this application.

[0027] Figure 3 This is a schematic diagram of a preferred embodiment of the present application after a second dielectric layer and a via have been formed on the surface of a first dielectric layer.

[0028] Figure 4 This is a schematic diagram of an organic hydrophobic layer formed on the bottom of a through-hole, according to a preferred embodiment of this application.

[0029] Figure 5 This is a schematic diagram of a tantalum layer formed on the sidewall of a through-hole, according to a preferred embodiment of this application.

[0030] Figure 6 This is a schematic diagram of a preferred embodiment of the present application after the removal of the organic hydrophobic layer.

[0031] Figure 7 This is a schematic diagram of a via filled with a second metal layer, provided as a preferred embodiment of the present application.

[0032] In the figure: 10. Substrate; 11. First dielectric layer; 12. First metal layer; 13. Second dielectric layer; 14. Trench and via structure; 15. Trench; 16. Via; 17. Organic hydrophobic layer; 18. Tantalum layer; 19. Second metal layer. Detailed Implementation

[0033] In advanced nodes, as the diameter of vias continues to decrease, the overall thickness of the diffusion barrier layer using a combination of TaN and Ta also becomes increasingly thinner. This leads to poorer interfacial affinity of the diffusion barrier layer, often resulting in film pitting and peeling defects, causing low yields. Furthermore, the thickness of the diffusion barrier layer as a proportion of the total via diameter is increasing, making it difficult to reduce subsequent contact resistance and RC delay. Additionally, the deposition of the diffusion barrier layer at the bottom of the via increases contact resistance. This application provides an interconnect structure fabrication method, including: Provide substrate; A first dielectric layer is formed on the surface of the substrate, and a first metal layer located in the first dielectric layer is formed on the surface of the first dielectric layer. A second dielectric layer is formed on the surface of the first dielectric layer to cover the first metal layer, and the material of the second dielectric layer includes a low dielectric constant material; A through-hole is formed on the surface of the second dielectric layer, with its bottom surface connected to the surface of the first metal layer; Using a vapor-phase self-assembly process, a monolayer organic hydrophobic layer is selectively formed on the exposed surface of the first metal layer at the bottom of the via. The sidewalls of the via are first treated with nitrogen free radicals excited by metastable particles to improve the adhesion of the low dielectric constant material surface on the sidewalls and the ability to block interfacial diffusion. A tantalum layer is selectively formed on the sidewall after the first treatment, while the formation of the tantalum layer on the surface of the organic hydrophobic layer is inhibited. Remove the organic hydrophobic layer and fill the via within the tantalum layer with a second metal layer electrically connected to the first metal layer.

[0034] This application embodiment improves the deposition quality of the tantalum layer by enhancing the adhesion of the sidewall surface of the low dielectric constant material and its ability to block interfacial diffusion. This allows a single tantalum layer to function as a diffusion barrier layer, eliminating the need for tantalum nitride in the diffusion barrier layer. As a result, the total thickness of the diffusion barrier layer can be reduced, thereby effectively reducing the proportion of the diffusion barrier layer's resistance in the overall via resistance. Furthermore, by avoiding the formation of the tantalum layer at the bottom of the via, the second metal layer can be directly electrically connected to the first metal layer, further reducing the interfacial contact resistance. This significantly reduces the subsequent contact resistance and RC delay.

[0035] This application also provides an interconnect structure, which is obtained using the interconnect structure fabrication method described above.

[0036] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0037] refer to Figure 1 In a first aspect, embodiments of this application provide a method for fabricating an interconnect structure, which may sequentially include the following steps: Step S11: Provide a substrate.

[0038] refer to Figure 2 In some embodiments, a substrate 10 is used for further forming the interconnect structure provided in the embodiments of this application on the substrate 10. The substrate 10 may include any suitable type of semiconductor substrate and material. For example, the substrate 10 may include a silicon (Si) substrate, a germanium (Ge) substrate, or a germanium-silicon (SiGe) substrate, or a III / V compound semiconductor substrate, such as a gallium arsenide (GaAs) substrate, an indium gallium arsenide (InGaAs) substrate, or similar materials, etc.

[0039] In some embodiments, substrate 10 may include a wafer.

[0040] Step S12: Form a first metal layer located in the first dielectric layer on the surface of the substrate.

[0041] refer to Figure 2 In some embodiments, a deposition process can be used to form a first dielectric layer 11 on the surface of the substrate 10. A first metal layer 12 located within the first dielectric layer 11 can be formed using processes such as photolithography and etching, such that the surface of the first metal layer 12 is exposed above the surface of the first dielectric layer 11. The bottom of the first metal layer 12 may be located on the surface of the substrate 10.

[0042] In some embodiments, the material of the first metal layer 12 may include copper (Cu), aluminum (Al), ruthenium (Ru), molybdenum (Mo), etc.

[0043] In some embodiments, the material of the first dielectric layer 11 may include a low dielectric constant material (or an ultra-low dielectric constant material), etc.

[0044] Step S13: Form a second dielectric layer on the surface of the first dielectric layer, and form a via connecting the first metal layer on the surface of the second dielectric layer.

[0045] refer to Figure 3 In some embodiments, a deposition process may be used to form a second dielectric layer 13 on the surface of the first dielectric layer 11.

[0046] In some embodiments, the second dielectric layer 13 may be an interlayer dielectric layer and may be used to form a back-end metal interconnect structure, etc.

[0047] In some embodiments, the material of the second dielectric layer 13 includes a low dielectric constant material (or an ultra-low dielectric constant material).

[0048] In some embodiments, the material of the second dielectric layer 13 includes a silicon-based low dielectric constant material (or a silicon-based ultra-low dielectric constant material), such as SiOCH.

[0049] In some embodiments, patterning processes, such as photolithography and etching, can be used to form a through-hole 16 on the surface of the second dielectric layer 13, with the bottom connected to the first metal layer 12.

[0050] refer to Figure 3 In some embodiments, a trench and a via structure 14 containing a via 16 may be formed on the surface of the second dielectric layer 13, and the bottom of the via 16 contained in the trench and via structure 14 is located on the surface of the first metal layer 12, thereby forming a via 16 on the surface of the second dielectric layer 13 whose bottom is connected to the surface of the first metal layer 12.

[0051] In some embodiments, the trench and via structure 14 includes a connected trench 15 and a via 16. The trench 15 may be located on the surface of the second dielectric layer 13, and the bottom of the trench 15 is located within the second dielectric layer 13; the top of the via 16 is connected to the bottom of the trench 15, and the bottom of the via 16 is connected to the surface of the first metal layer 12, such as... Figure 3 As shown. By filling the trench and via structure 14 with metal (second metal layer), a metal interconnect structure electrically connected to the first metal layer 12 can be formed (see reference). Figure 7 ).

[0052] In some embodiments, a via can be formed on the surface of the second dielectric layer, with the top of the via exposed on the surface of the second dielectric layer and the bottom of the via connected to the surface of the first metal layer, and a metal via is formed by filling the via with metal.

[0053] In some embodiments, a third dielectric layer (not shown) may be formed on the surface of the second dielectric layer after the metal via is formed, and a trench is formed on the surface of the third dielectric layer to connect the top of the metal via to the bottom. By filling the trench with metal and forming an electrical connection with the metal via, a metal interconnect structure electrically connected to the first metal layer is formed.

[0054] In some embodiments, the metal (second metal layer) used to fill the through hole 16 includes copper (Cu) and the like.

[0055] For back-end logic processes, diffusion barrier layers in copper (Cu) vias typically employ a bilayer structure of tantalum nitride (TaN) and tantalum (Ta). At advanced nodes, as via diameters decrease, the overall thickness of the diffusion barrier layer using the TaN and Ta combination becomes increasingly critical. This leads to poorer interfacial affinity, often resulting in pitting and peeling defects, causing low yields and hindering further reduction in the total thickness of the diffusion barrier layer. Furthermore, since the diffusion barrier layer is deposited not only on the sidewalls of the via but also on the bottom, for small-sized vias at advanced nodes, this deposition at the bottom further increases contact resistance. These issues result in significant RC delay, making it difficult to reduce back-end contact resistance. Therefore, the process methods provided in this application can improve these problems, effectively reducing the total thickness of the diffusion barrier layer, lowering back-end contact resistance and RC delay, and improving interconnect stability.

[0056] Step S14: Using a vapor phase self-assembly process, a monolayer organic hydrophobic layer is selectively formed on the bottom of the through-hole.

[0057] refer to Figure 3 In some embodiments, hydrogen radicals excited by metastable particles can be used to perform a third treatment on the exposed surface of the first metal layer 12 at the bottom of the via 16 to activate the exposed surface of the first metal layer 12.

[0058] By performing a third treatment, active hydrogen atoms (hydrogen radicals) in low-temperature hydrogen plasma can be used to reduce the metal oxides generated on the surface of the first metal layer 12 to elemental metals at low energy levels. This also removes C impurities or CH-based polymers that may remain on the surface of the first metal layer 12 after the previous process (hydrogen radicals can break these bonds to form volatile CH compounds), thus cleaning the surface of the first metal layer 12. Furthermore, the active hydrogen atoms can combine with the atoms on the cleaned surface of the first metal layer 12 to form dangling bonds, making the first metal layer 12 surface active. This helps improve the selectivity and adhesion of the organic hydrophobic layer that will be adsorbed onto the bottom of the through-hole 16.

[0059] In some embodiments, the hydrogen radicals required for the third treatment can be obtained by exciting hydrogen gas with helium metastable particles and filtering out charged particles therein. The helium metastable particles are obtained by exciting helium gas and filtering out charged particles therein.

[0060] In some embodiments, during the third process, the flow rate ratio between the introduced hydrogen and helium is 1 to 10 (hydrogen flow rate: helium flow rate = 1:1 to 10:1). For example, the flow rate ratio of hydrogen to helium can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, or any value between any two of the aforementioned flow rate ratios.

[0061] In some embodiments, during the third processing, the helium flow rate is between 1000 sccm and 9000 sccm. For example, the helium flow rate can be 1000 sccm, 2000 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm, 8000 sccm, or 9000 sccm, or any value between any two of the aforementioned flow rates.

[0062] In some embodiments, the temperature during the third processing is 50°C to 200°C. For example, the temperature may be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or any value between any two of the aforementioned temperature values.

[0063] In some embodiments, when performing the third processing, the source power is 1W to 100W. For example, the source power can be 1W, 2W, 3W, 4W, 5W, 10W, 20W, 30W, 40W, 50W, 60W, 70W, 80W, 90W, or 100W, or any value between any two of the aforementioned power values.

[0064] In some embodiments, the pressure during the third processing is 10 mTorr to 1000 mTorr. For example, the pressure may be 10 mTorr, 20 mTorr, 30 mTorr, 40 mTorr, 50 mTorr, 80 mTorr, 100 mTorr, 200 mTorr, 500 mTorr, 900 mTorr, or 1000 mTorr, or any value between any two of the aforementioned pressure values.

[0065] In some embodiments, the time for performing the third processing is 5s to 300s. For example, the time can be 5s, 6s, 7s, 8s, 9s, 10s, 20s, 50s, 100s, 150s, 200s, 250s, 280s, or 300s, or any value between any two of the aforementioned time values.

[0066] In some embodiments, during the third processing, ion filtering is turned on and bias power is turned off.

[0067] By synergistically controlling the flow ratio, flow rate, temperature, source power, pressure, time, etc., hydrogen free radicals with lower energy and low-temperature activity can be obtained, thereby cleaning and activating the exposed surface of the first metal layer 12 and providing a more ideal selective deposition surface for the subsequent organic hydrophobic layer to be formed.

[0068] refer to Figure 4 In some embodiments, a vapor-phase self-assembly process may be used, and organic molecules containing thiols (-SH) or silicon (Si) may be used as precursors, while diluting gases may be added to selectively form a monolayer organic hydrophobic layer 17 on the exposed surface of the first metal layer 12 at the bottom of the via 16.

[0069] In some embodiments, the thiol-containing organic molecule may include alkyl thiols, such as n-octanethiol C8H17-SH.

[0070] In some embodiments, the silicon-containing organic molecule may include organosilanes (-SiH3) (e.g., aminosilanes, chlorosilanes, alkoxysilanes, etc.) or other molecules containing silicon functional groups.

[0071] In some embodiments, the diluent gas may include at least one of nitrogen, hydrogen, and inert gases (such as argon, helium, etc.).

[0072] Using a vapor-phase self-assembly process (Soak process), amphiphilic organic molecules (thiol-containing organic molecules or silicon-containing organic molecules) with specific "head groups" and "tail chains" can be transported to the deposition surface (the exposed surface of the first metal layer 12 at the bottom of the via 16) via vapor or aerosol. The "head groups" are selectively and firmly chemically adsorbed on the exposed surface of the first metal layer 12 at the bottom of the via 16, while the "tail chains" are arranged outwards to form a dense, monolayer, hydrophobic "molecular barrier" (organic hydrophobic layer 17).

[0073] In some embodiments, the aforementioned organic molecules can be dissolved in an organic solvent (e.g., isopropanol (IPA)) to form a solution, and introduced into the reaction chamber via aerosol or vaporization (generated by a Bubbler or Direct Liquid Injection (DLI) system) to form an organic hydrophobic layer 17 (which can act as a barrier layer to suppress electromigration or diffusion) on the exposed surface of the first metal layer 12 at the bottom of the through-hole 16. The IPA itself, as a solvent, can also participate in surface cleaning and conditioning. By adding a diluent gas to form a protective atmosphere, water and oxygen can be excluded, preventing premature hydrolysis and failure of the precursor, and avoiding the formation of multilayer molecules while ensuring monolayer self-assembly.

[0074] In some embodiments, when performing a gas-phase self-assembly process, the total flow rate of the process gases (precursor and dilution gas) is 1 sccm to 100 sccm. For example, the flow rate of the process gases can be 1 sccm, 2 sccm, 3 sccm, 4 sccm, 5 sccm, 10 sccm, 20 sccm, 50 sccm, 90 sccm, or 100 sccm, or any value between any two of the aforementioned flow rate values.

[0075] In some embodiments, the temperature for performing the vapor-phase self-assembly process is 50°C to 150°C. For example, the temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C, or any value between any two of the aforementioned temperature values. Within the aforementioned temperature range, problems such as slow and incomplete reactions due to excessively low temperatures, or the potential decomposition of organic molecules or multilayer physical adsorption due to excessively high temperatures, can be avoided.

[0076] In some embodiments, when performing the vapor phase self-assembly process, the pressure is 100 mTorr to 10000 mTorr to achieve low-pressure vapor phase deposition. For example, the pressure can be 100 mTorr, 200 mTorr, 500 mTorr, 800 mTorr, 1000 mTorr, 2000 mTorr, 5000 mTorr, 9000 mTorr, or 10000 mTorr, or any value between any two of the aforementioned pressure values.

[0077] In some embodiments, when performing the gas-phase self-assembly process, the time is 10s to 300s, which is sufficient to achieve monolayer saturation adsorption. For example, the time can be 10s, 15s, 20s, 30s, 50s, 90s, 100s, 120s, 150s, 200s, 250s, 280s, or 300s, or any value between any two of the aforementioned time values.

[0078] Thus, through the coordinated control of the above-mentioned flow rate, temperature, pressure, time, etc., a dense, monolayer, hydrophobic organic hydrophobic layer 17 can be selectively obtained on the exposed surface of the first metal layer 12. This layer is used to prevent the tantalum layer from being deposited on the surface of the organic hydrophobic layer 17 during subsequent tantalum layer deposition, thereby avoiding the deposition of the tantalum layer on the bottom of the via 16 and thus preventing an increase in the interfacial contact resistance between the upper and lower layers.

[0079] Step S15: Use nitrogen free radicals excited by metastable particles to perform the first treatment on the sidewall of the through hole.

[0080] refer to Figure 4In some embodiments, nitrogen radicals excited by metastable particles can be used to perform a first treatment on the sidewalls of the via 16 to improve the adhesion and interfacial diffusion resistance of the low dielectric constant material surface on the sidewalls by modifying the surface of the low dielectric constant material on the sidewalls.

[0081] It should be noted that, in relation to such Figure 4 When the sidewall of the through-hole 16 is treated first, the inner wall (sidewall and bottom wall) of the groove 15 is also treated simultaneously. That is, the first treatment is performed on the entire inner wall of the groove and through-hole structure 14. If the groove and through-hole are formed separately and the groove and through-hole are filled with metal separately, then the first treatment is performed independently on the sidewall of the through-hole.

[0082] By performing the first treatment, nitrogen atoms (active nitrogen species in plasma (mainly nitrogen free radicals)) are adsorbed onto the surface of the low dielectric constant material on the inner wall of the trench and through-hole structure 14 to form dangling bonds, which can optimize the surface state (surface energy). Therefore, it can enhance the adhesion between tantalum and the inner wall surface of the low dielectric constant material, which is beneficial to improving the continuity and uniformity of the subsequently deposited tantalum layer on the inner wall. This allows the tantalum layer to form a more continuous and uniform film on the surface-modified inner wall, thereby reducing the contact resistance.

[0083] Furthermore, through the first treatment, nitrogen atoms (nitrogen free radicals) react with the bonding bonds (such as Si-CH3 or Si-H) on the surface of the low dielectric constant material on the inner wall at low energy, forming a nitrogen-rich surface layer on the surface of the low dielectric constant material on the inner wall. This reduces defect channels, blocks interfacial diffusion, and effectively prevents the diffusion of metal (such as Cu) atoms, moisture, or other impurities into the porous low dielectric constant material in subsequent processes, thus preventing the degradation of electrical properties (such as increased k-value, increased leakage current, etc.).

[0084] The essence of low-k materials: The "low-k" characteristic of advanced low-k materials (such as SiOCH) originates from their chemical and physical structures. Chemically, it involves replacing the highly polar Si-OH groups in traditional SiO2 with low-polarity Si-CH3 groups, thereby reducing the material's electronic polarizability. Physically, it involves introducing nanoscale pores. Since the k-value of air is approximately 1, it lowers the overall effective dielectric constant. The essence of the first treatment of the inner wall using nitrogen free radicals excited by metastable particles in this application is to allow nitrogen atoms to adsorb onto the surface of the low-k material on the inner wall at low energy, forming dangling bonds. This replaces or covers the Si-CH3 groups on the surface of the low-k material with highly polar, dense Si-N bonds, preventing deep penetration of nitrogen atoms and a sharp increase in the overall k-value of the low-k material.

[0085] By performing a first treatment, the low-k material on the inner wall undergoes superficial modification, causing the reaction to occur only on the surface of the low-k material, forming an extremely thin "skin." This skin can seal the pores on the surface of the low-k material without altering the structure and stress state of the low-k material itself. Thus, while constructing an effective sealing barrier, the overall low-k characteristics of the second dielectric layer 13 are maintained.

[0086] Furthermore, during the etching process to form the via 16, the plasma damages the low-k material on the sidewalls, forming a "modified damage layer". This damage layer can be repaired and stabilized by first treating the sidewalls of the via 16 with nitrogen free radicals excited by metastable particles.

[0087] In some embodiments, the nitrogen radicals required for the first treatment can be obtained by exciting nitrogen gas with helium metastable particles and filtering out charged particles therein. The helium metastable particles can be obtained by exciting helium gas and filtering out charged particles therein.

[0088] In some embodiments, during the first process, the flow rate ratio between the nitrogen flow rate and the helium flow rate is 1 to 10 (nitrogen flow rate: helium flow rate = 1:1 to 10:1). For example, the nitrogen to helium flow rate ratio can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, or any value between any two of the aforementioned flow rate ratios.

[0089] In some embodiments, during the first process, the flow rate of helium is 1000 sccm to 9000 sccm. For example, the flow rate of helium can be 1000 sccm, 2000 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm, 8000 sccm, or 9000 sccm, or any value between any two of the aforementioned flow rates.

[0090] In some embodiments, the temperature during the first processing is 50°C to 200°C. For example, the temperature may be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or any value between any two of the aforementioned temperature values.

[0091] In some embodiments, the source power is 1W to 100W when performing the first process. For example, the source power may be 1W, 2W, 3W, 4W, 5W, 10W, 20W, 30W, 40W, 50W, 60W, 70W, 80W, 90W or 100W, or any value between any two of the aforementioned power values.

[0092] In some embodiments, the pressure during the first treatment is 10 mTorr to 1000 mTorr. For example, the pressure may be 10 mTorr, 20 mTorr, 30 mTorr, 40 mTorr, 50 mTorr, 80 mTorr, 100 mTorr, 200 mTorr, 500 mTorr, 900 mTorr, or 1000 mTorr, or any value between any two of the aforementioned pressure values.

[0093] In some embodiments, the time for performing the first process is 5s to 300s. For example, the time can be 5s, 6s, 7s, 8s, 9s, 10s, 20s, 50s, 100s, 150s, 200s, 250s, 280s, or 300s, or any value between any two of the aforementioned time values.

[0094] In some embodiments, during the first processing, ion filtering is turned on and bias power is turned off.

[0095] By synergistically controlling the flow ratio, flow rate, temperature, source power, pressure, and time, lower-energy nitrogen free radicals are obtained (achieving a completely isotropic reaction, reducing violent reactions on the structural surface or sputtering reactions on some sidewalls). This enables ultra-low-energy surface modification treatment of the low-dielectric-constant material on the inner wall of the trench and through-hole structure 14, enhancing the adhesion between the subsequently deposited tantalum and the inner wall surface of the low-dielectric-constant material, and constructing an effective sealing barrier.

[0096] Step S16: Selectively form a tantalum layer on the sidewall of the via while inhibiting the formation of the tantalum layer on the surface of the organic hydrophobic layer.

[0097] refer to Figure 5 In some embodiments, a deposition process can be used to form a tantalum layer 18 on the inner wall of the surface-modified trench and via structure 14 (the tantalum layer can be simultaneously deposited on the surface of the second dielectric layer 13 other than the trench and via structure 14). Figure 5 (The details are omitted here), allowing the deposited tantalum layer 18 to directly contact the low dielectric constant material on the inner wall after the surface has undergone the first treatment. Furthermore, by utilizing the monolayer organic hydrophobic layer 17 deposited on the bottom of the via 16, the deposition of the tantalum layer 18 on the bottom region of the via 16 occupied by the organic hydrophobic layer 17 can be suppressed, and the tantalum layer 18 can be selectively formed on the inner wall of the trench and via structure 14 outside the region occupied by the organic hydrophobic layer 17, thereby avoiding the deposition of the tantalum layer 18 on the surface of the first metal layer 12 in the bottom region of the via 16 occupied by the organic hydrophobic layer 17.

[0098] In some embodiments, an atomic layer deposition process may be used to conformally form a tantalum layer 18 on the inner wall of the trench and via structure 14 after the first treatment.

[0099] By using nitrogen free radicals excited by metastable particles to perform a first surface modification treatment on the low dielectric constant material on the inner wall of the trench and via structure 14, the adhesion between tantalum and the inner wall surface of the low dielectric constant material can be greatly enhanced. This allows the tantalum layer 18 to form a continuous and uniform film on the surface of the surface-modified low dielectric constant material on the inner wall, effectively eliminating film pits and peeling defects and improving yield. Furthermore, since the deposition quality of the tantalum layer 18 is significantly improved, it can play an effective diffusion barrier role. This allows the use of a single tantalum layer 18 to serve as a diffusion barrier layer on its own, eliminating the need for tantalum nitride in the diffusion barrier layer. This reduces the total thickness of the diffusion barrier layer and effectively reduces the proportion of the diffusion barrier layer's resistance in the overall via 16.

[0100] refer to Figure 5 In some embodiments, after depositing the tantalum layer 18, the surface of the tantalum layer 18 can be subjected to a second treatment using hydrogen radicals excited by metastable particles to reduce the surface state density.

[0101] By using metastable particle-excited hydrogen radicals to perform a second treatment on the surface of tantalum layer 18, oxide layers and impurities can be removed at low energy and low temperature, thus cleaning the surface of tantalum layer 18. Ta metal surfaces readily form non-stoichiometric tantalum oxide (TaO) with very poor conductivity in air. x Using active hydrogen atoms (hydrogen radicals) in low-temperature hydrogen plasma, TaO generated on the surface of tantalum layer 18 can be... x It reduces to metallic Ta and removes residual C impurities or CH-based polymers from the Ta deposition surface (hydrogen radicals can break these bonds, forming volatile CH compounds). Furthermore, active hydrogen atoms can combine with cleaned Ta surface atoms (especially residual oxygen or unsaturated bonds) to form Ta-H bonds, effectively "passivating" dangling bonds and highly active sites, thus reducing surface state density. A clean, uniform, and hydrogen-terminated tantalum layer provides a more ideal nucleation surface for subsequent film deposition, contributing to the growth of denser, more uniform, and higher-crystal-quality films, thereby further reducing contact resistance and RC delay.

[0102] In some embodiments, the hydrogen radicals required for the second treatment can be obtained by exciting hydrogen gas with helium metastable particles and filtering out charged particles therein. The helium metastable particles can be obtained by exciting helium gas and filtering out charged particles therein.

[0103] In some embodiments, during the second treatment, argon gas is also added to the hydrogen gas to adjust the hydrogen concentration. By adding argon gas to the hydrogen gas, excess hydrogen atoms on the surface of the tantalum layer 18 can be removed, preventing the formation of compounds due to excessive hydrogen atom content reacting with Ta.

[0104] In some embodiments, during the second process, the flow rate ratio between the introduced hydrogen gas and the argon gas is: hydrogen flow rate : argon flow rate = 1:1 to 1:3. For example, the flow rate ratio of hydrogen to argon gas can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.5, 1:1.8, 1:2, 1:2.1, 1:2.5, 1:2.9, or 1:3, etc., and the flow rate ratio of argon gas can vary continuously between 1 and 3.

[0105] In some embodiments, during the second process, the flow rate ratio between the flow rate of the hydrogen and argon mixture and the flow rate of helium is 0.1 to 2 (hydrogen and argon mixture flow rate: helium flow rate = 0.1:1 to 2:1). For example, the flow rate ratio of the hydrogen and argon mixture to helium can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2, or any value between any two of the aforementioned flow rate ratios.

[0106] In some embodiments, the flow rate of helium gas during the second processing is 1000 sccm to 2000 sccm. For example, the flow rate of helium gas may be 1000 sccm, 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm, 1500 sccm, 1600 sccm, 1700 sccm, 1800 sccm, 1900 sccm, or 2000 sccm, or any value between any two of the aforementioned flow rate values.

[0107] In some embodiments, the temperature during the second processing is 100°C to 200°C. For example, the temperature may be 100°C, 105°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, or any value between any two of the aforementioned temperature values.

[0108] In some embodiments, when performing the second processing, the source power is 100W to 500W. For example, the source power may be 100W, 110W, 130W, 150W, 170W, 200W, 250W, 300W, 350W, 400W, 450W, or 500W, or any value between any two of the aforementioned power values.

[0109] In some embodiments, the pressure during the second processing is 10 mTorr to 1000 mTorr. For example, the pressure may be 10 mTorr, 30 mTorr, 50 mTorr, 70 mTorr, 90 mTorr, 100 mTorr, 200 mTorr, 500 mTorr, 800 mTorr, or 1000 mTorr, or any value between any two of the aforementioned pressure values.

[0110] In some embodiments, the time for performing the second processing is 5s to 300s. For example, the time can be 5s, 6s, 7s, 8s, 9s, 10s, 30s, 50s, 70s, 100s, 150s, 200s, 250s, 290s, or 300s, or any value between any two of the aforementioned time values.

[0111] In some embodiments, during the second processing, ion filtering is turned on and bias power is turned off.

[0112] By synergistically controlling the flow ratio, flow rate, temperature, source power, pressure, time, etc., lower energy and lower temperature hydrogen radicals can be obtained (achieving a completely isotropic reaction, reducing violent reactions on the structural surface or sputtering reactions on some sidewalls), thus achieving cleaning and passivation of the tantalum layer 18 surface, providing a more ideal nucleation surface for subsequent film deposition.

[0113] Step S17: Remove the organic hydrophobic layer and fill the vias within the tantalum layer with a second metal layer that is electrically connected to the first metal layer.

[0114] refer to Figure 6 In some embodiments, the organic hydrophobic layer 17 can be removed by thermal decomposition. By heating the substrate 10, the organic hydrophobic layer 17 can be heated and thermally decomposed at high temperature, decomposing into gaseous small molecules (such as CH4, C2H4, H2S, etc.), which can be completely removed by vacuuming out the reaction chamber.

[0115] In some embodiments, the temperature for thermally decomposing and removing the organic hydrophobic layer 17 is 300°C to 400°C. For example, the temperature may be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, or 400°C, or any value between any two of the aforementioned temperature values.

[0116] In some embodiments, such as Figure 6 As shown, after removing the organic hydrophobic layer 17, hydrogen free radicals excited by metastable particles can be used to perform a fourth treatment on the exposed surface of the first metal layer 12 at the bottom of the through hole 16, so as to activate the exposed surface of the first metal layer 12.

[0117] By performing a fourth process, active hydrogen atoms (hydrogen radicals) in low-temperature hydrogen plasma can be used to reduce the metal oxides generated on the surface of the first metal layer 12 to elemental metals at low energy levels. This process also removes carbon impurities or CH-based polymers that may remain on the surface of the first metal layer 12 after previous processes (hydrogen radicals can break these bonds to form volatile CH compounds), thus cleaning the surface of the first metal layer 12. Furthermore, the active hydrogen atoms can combine with the atoms on the cleaned surface of the first metal layer 12 to form dangling bonds, making the first metal layer 12 surface active. This helps improve the deposition quality on the surface of the first metal layer 12 when filling the second metal layer in the trench and via structure 14, and can further reduce the interfacial contact resistance.

[0118] In some embodiments, the flow ratio, flow rate, temperature, power, pressure, time, etc. used when performing the fourth process may refer to the flow ratio, flow rate, temperature, power, pressure, time, etc. used when performing the third process as described above.

[0119] In some embodiments, the second process provided in the above embodiments can be performed after the removal of the organic hydrophobic layer 17, and during the second process, a fourth process can be simultaneously performed on the exposed surface of the first metal layer 12 at the bottom of the via 16 using hydrogen free radicals. In other words, the second process provided in the above embodiments can be combined with the fourth process provided in the above embodiments into the same process (the same step) after the removal of the organic hydrophobic layer 17, so as to simultaneously treat the surface of the tantalum layer 18 and the exposed surface of the first metal layer 12. When the fourth process and the second process are performed together, the process regime (flow rate ratio, flow rate, temperature, power, pressure, time, etc.) used in the second process provided in the above embodiments can be used.

[0120] refer to Figure 7 In some embodiments, a deposition process can be used to fill the trenches and vias 14 within the tantalum layer 18 with a second metal layer 19, thus completely filling the trenches and vias 14. This allows the filled second metal layer 19 to directly contact the tantalum layer 18 after its surface has undergone a second treatment, resulting in a denser, more uniform, and higher-quality film of the second metal layer 19, further reducing contact resistance. Furthermore, the filled second metal layer 19 directly contacts the surface of the first metal layer 12 exposed at the bottom of the via 16, eliminating the problem of increased contact resistance caused by the deposition of a diffusion barrier layer at the bottom of the via in existing processes. This also improves the interfacial contact quality between the second metal layer 19 and the first metal layer 12, further reducing contact resistance.

[0121] The excess metal material deposited on the surface of the second dielectric layer 13 can then be removed by a planarization process (such as chemical mechanical polishing). This forms a metal interconnect structure that allows the second metal layer 19 to be directly electrically connected to the first metal layer 12.

[0122] In some embodiments, the material of the second metal layer 19 includes copper.

[0123] By using nitrogen free radicals excited by metastable particles to perform a first treatment on the inner wall of the trench and via structure 14, the adhesion of tantalum and low dielectric constant materials to the inner wall surface is enhanced, improving the deposition quality of the tantalum layer 18 and constructing an effective sealing barrier that can effectively prevent Cu atoms from diffusing into the porous low dielectric constant material. By using hydrogen free radicals excited by metastable particles to perform a second treatment on the surface of the tantalum layer 18 deposited on the inner wall, a more ideal nucleation surface is provided for the deposition of the second metal layer 19, enabling the growth of a denser, more uniform, and higher-crystal-quality copper film. Therefore, using only a single tantalum layer 18 can independently serve as a diffusion barrier layer, reducing the total thickness of the diffusion barrier layer and the proportion of its resistance in the overall via 16, thereby reducing the subsequent contact resistance and RC delay, well meeting the technical requirements at lower nodes. Furthermore, by enabling a high-quality direct electrical connection between the second metal layer 19 and the first metal layer 12, the interfacial contact resistance is further reduced.

[0124] In a second aspect, embodiments of this application also provide an interconnect structure, which is obtained using the interconnect structure fabrication method provided in any of the embodiments of the first aspect described above.

[0125] refer to Figure 7 In some embodiments, the interconnect structure is disposed on a substrate 10. A first dielectric layer 11 is disposed on the surface of the substrate 10, and a first metal layer 12 is disposed in the first dielectric layer 11. The surface of the first metal layer 12 is exposed on the surface of the first dielectric layer 11, and the bottom of the first metal layer 12 may be located on the surface of the substrate 10. A second dielectric layer 13 of a low dielectric constant material is disposed on the surface of the first dielectric layer 11, and a via 16 with its bottom connected to the surface of the first metal layer 12 is disposed on the surface of the second dielectric layer 13. A tantalum layer 18 is disposed on the sidewall of the via 16, and a second metal layer 19 directly electrically connected to the first metal layer 12 is filled in the via 16 within the tantalum layer 18, forming a metal via.

[0126] In some embodiments, a trench and a via structure 14 containing a via 16 may be provided on the surface of the second dielectric layer 13. The bottom of the via 16 contained in the trench and the via structure 14 is located on the surface of the first metal layer 12, thereby forming a via 16 on the surface of the second dielectric layer 13 whose bottom is connected to the surface of the first metal layer 12.

[0127] In some embodiments, the trench and via structure 14 includes a connected trench 15 and a via 16. The trench 15 may be located on the surface of the second dielectric layer 13, with its bottom located within the second dielectric layer 13. The top of the via 16 is connected to the bottom of the trench 15, and its bottom is connected to the surface of the first metal layer 12. A tantalum layer 18 is provided on the inner wall of the trench and via structure 14, excluding the bottom of the via 16 (no tantalum layer 18 is provided on the bottom of the via 16). By filling the trench and via structure 14 with the second metal layer 19, a metal interconnect structure directly electrically connected to the first metal layer 12 can be formed.

[0128] In some embodiments, one side surface (outer surface) of the tantalum layer 18 is in direct contact with a low dielectric constant material on the inner wall of the trench and via structure 14, and the other side surface (inner surface) of the tantalum layer 18 is in direct contact with a second metal layer 19 filled in the trench and via structure 14.

[0129] In some embodiments, a diffusion barrier layer is provided between the second metal layer 19 and the second dielectric layer 13. The diffusion barrier layer is formed of a tantalum layer 18 (the material of the diffusion barrier layer is tantalum. The diffusion barrier layer does not contain a film layer of materials other than tantalum layer 18, such as tantalum nitride layer).

[0130] In this process, the surface of the low-dielectric-constant material on the inner wall of the trench and via structure 14 undergoes a first treatment to modify the surface, enhancing adhesion and reducing defect channels. The tantalum layer 18, serving as a diffusion barrier layer, is directly deposited on the surface of the modified low-dielectric-constant material on the inner wall via its outer surface, improving the uniformity and density of the tantalum layer 18 deposition. Furthermore, the inner surface of the tantalum layer 18 undergoes a second treatment to reduce the surface state density, providing a more ideal nucleation surface. The second metal layer 19 is then well deposited and filled on the inner surface of the tantalum layer 18 after the surface state density has been reduced. Thus, by using only the tantalum layer 18 as a diffusion barrier layer, the total thickness of the diffusion barrier layer is reduced (compared to the overall film thickness using a combination of TaN and Ta), effectively reducing the proportion of the diffusion barrier layer's resistance in the overall via 16, thereby reducing the subsequent contact resistance and RC delay.

[0131] Furthermore, when fabricating the interconnect structure, by first forming a monolayer organic hydrophobic layer 17 on the exposed surface of the first metal layer 12 at the bottom of the via 16, the deposition of the subsequent tantalum layer 18 on the bottom of the via 16 can be suppressed. Thus, after removing the organic hydrophobic layer 17, the second metal layer 19 subsequently filled in the via 16 can be directly electrically connected to the first metal layer 12 below, thereby further reducing the contact resistance.

[0132] In a third aspect, embodiments of this application also provide a plasma processing apparatus for performing the interconnect structure fabrication method corresponding to the above embodiments to form the interconnect structure corresponding to the above embodiments. The plasma processing apparatus includes inductively coupled plasma (ICP) etching equipment or capacitively coupled plasma (CCP) etching equipment, etc.

[0133] In other aspects, embodiments of this application also provide an electronic device, including an interconnect structure obtained using the interconnect structure fabrication method of the above embodiments. The electronic device can be a storage device, mobile phone, computer, tablet computer, electronic instrument, television, artificial intelligence device, etc.

[0134] In summary, this embodiment of the application improves the deposition quality of the tantalum layer 18 by enhancing the adhesion and interfacial diffusion barrier capabilities of the sidewalls (inner walls of the trench and via structure 14) of the low dielectric constant material in the via 16. This allows the single tantalum layer 18 to function as a diffusion barrier layer independently, eliminating the need for tantalum nitride. Consequently, the total thickness of the diffusion barrier layer is reduced, effectively lowering its proportion of the overall resistance in the via 16. Furthermore, by preventing the tantalum layer 18 from forming at the bottom of the via 16, the second metal layer 19 filled in the via 16 can directly connect to the underlying first metal layer 12, further reducing interfacial contact resistance. This significantly reduces subsequent contact resistance and RC delay. The process steps of this embodiment are highly compatible, enhancing the adhesion of subsequent metal interconnects, achieving lower resistance and interconnect stability, and effectively meeting the technical requirements of advanced nodes.

[0135] The above are merely preferred embodiments of this application. These embodiments are not intended to limit the scope of protection of this application. Therefore, any equivalent changes made based on the description and drawings of this application should also be included within the scope of protection of this application.

Claims

1. A method for fabricating an interconnect structure, characterized in that, include: Provide substrate; A first dielectric layer is formed on the surface of the substrate, and a first metal layer located in the first dielectric layer is formed on the surface of the first dielectric layer. A second dielectric layer is formed on the surface of the first dielectric layer to cover the first metal layer, and the material of the second dielectric layer includes a low dielectric constant material; A through-hole is formed on the surface of the second dielectric layer, with its bottom surface connected to the surface of the first metal layer; Using a vapor-phase self-assembly process, a monolayer organic hydrophobic layer is selectively formed on the exposed surface of the first metal layer at the bottom of the via. The sidewalls of the via are first treated with nitrogen free radicals excited by metastable particles to improve the adhesion of the low dielectric constant material surface on the sidewalls and the ability to block interfacial diffusion. A tantalum layer is selectively formed on the sidewall after the first treatment, while the formation of the tantalum layer on the surface of the organic hydrophobic layer is inhibited. Remove the organic hydrophobic layer and fill the via within the tantalum layer with a second metal layer electrically connected to the first metal layer.

2. The method for fabricating the interconnect structure according to claim 1, characterized in that, By performing the first treatment, nitrogen free radicals react with the bonding bonds on the surface of the low dielectric constant material on the sidewall to form a nitrogen-rich surface layer, thereby blocking interfacial diffusion and optimizing surface energy, and improving the continuity and uniformity of the tantalum layer when it is directly deposited on the sidewall; and / or, the low dielectric constant material includes a silicon-based low dielectric constant material.

3. The method for fabricating the interconnect structure according to claim 1, characterized in that, After forming the tantalum layer, the process further includes: using hydrogen radicals excited by metastable particles to perform a second treatment on the surface of the tantalum layer to reduce the surface state density.

4. The method for fabricating the interconnect structure according to claim 1, characterized in that, It also includes using hydrogen radicals excited by metastable particles to treat the exposed surface of the first metal layer at the bottom of the via with at least one of a third treatment and a fourth treatment to generate surface activity; wherein the third treatment is performed before the formation of the organic hydrophobic layer, and the fourth treatment is performed after the removal of the organic hydrophobic layer.

5. The method for fabricating the interconnect structure according to claim 1, characterized in that, The nitrogen free radicals are obtained by exciting nitrogen gas with helium metastable particles and filtering out charged particles. The helium metastable particles are obtained by exciting helium gas and filtering out charged particles. During the first treatment, the helium flow rate is 1000 sccm to 9000 sccm, the nitrogen flow rate: helium flow rate = 1:1 to 10:1, the temperature is 50℃ to 200℃, the source power is 1W to 100W, the pressure is 10mTorr to 1000mTorr, the time is 5s to 300s, and the ion filter is turned on while the bias power is turned off.

6. The method for fabricating the interconnect structure according to claim 3, characterized in that, The hydrogen radicals are obtained by exciting hydrogen gas with helium metastable particles and filtering out charged particles. The helium metastable particles are obtained by exciting helium gas and filtering out charged particles. During the second treatment, argon gas is added to the hydrogen gas to adjust its concentration. The helium flow rate is 1000 sccm to 2000 sccm, the hydrogen-argon mixture flow rate:helium flow rate = 0.1:1 to 2:1, the hydrogen flow rate:argon flow rate = 1:1 to 1:3, the temperature is 100℃ to 200℃, the source power is 100W to 500W, the pressure is 10mTorr to 1000mTorr, the time is 5s to 300s, and the ion filter is turned on while the bias power is turned off.

7. The method for fabricating the interconnect structure according to claim 4, characterized in that, The hydrogen free radicals are obtained by exciting hydrogen gas with helium metastable particles and filtering out charged particles. The helium metastable particles are obtained by exciting helium gas and filtering out charged particles. During the third or fourth treatment, the helium flow rate is 1000 sccm to 9000 sccm, the hydrogen flow rate: helium flow rate = 1:1 to 10:1, the temperature is 50℃ to 200℃, the source power is 1W to 100W, the pressure is 10mTorr to 1000mTorr, the time is 5s to 300s, and the ion filter is turned on while the bias power is turned off.

8. The method for fabricating the interconnect structure according to claim 1, characterized in that, The organic hydrophobic layer is formed by using thiol-containing organic molecules or silicon-containing organic molecules as precursors and adding diluent gases.

9. The method for fabricating an interconnect structure according to claim 8, characterized in that, The thiol-containing organic molecule includes alkyl thiols, and the silicon-containing organic molecule includes organosilanes; and / or, when performing the gas-phase self-assembly process, the temperature is 50℃~150℃, the pressure is 100mTorr~10000mTorr, and the time is 10s~300s; and / or, the dilution gas includes at least one of nitrogen, hydrogen, and inert gas; and / or, the organic hydrophobic layer is removed by thermal decomposition at a temperature of 300℃~400℃.

10. An interconnection structure, characterized in that, It is obtained using the interconnect structure fabrication method as described in any one of claims 1-9.

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