Semiconductor structure and preparation method thereof

Abstract

The embodiment of the invention discloses a semiconductor structure and a preparation method thereof. The preparation method comprises the following steps: forming a first metal pattern on the surface of a substrate; performing first treatment on the surface of the first metal pattern by sequentially using plasma of hydrocarbon gas and steam of a coupling agent to form an adhesion promoting layer of a monomolecular layer; forming a dielectric layer made of a low dielectric constant material on the surface of the substrate, covering the top of the first metal pattern, and bonding the dielectric layer with the surface of the first metal pattern; forming a through hole of which the bottom is connected with the top of the first metal pattern on the surface of the dielectric layer; carrying out second treatment on the side wall of the through hole by using nitrogen free radicals so as to modify the surface of the low-dielectric-constant material on the side wall of the through hole; forming a tantalum layer on the side wall of the through hole; and filling a second metal layer electrically connected with the first metal pattern in the through hole. According to the embodiment of the invention, the adhesion of rear-section metal interconnection can be enhanced, and lower resistance and interconnection reliability and stability are realized.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and in particular to a semiconductor structure and its preparation method. Background Technology

[0002] Traditional double damascus patterning faces multiple limitations in the miniaturization era, including difficulty in further reducing effective resistance and RC delay, as well as challenges in patterning and filling at high aspect ratios. To address these challenges, the industry has explored the following evolutionary path: for the most critical and densely patterned bottom metal layers (such as M1 and M2), a subtractive patterning process (depositing metal first, then etching the pattern) is adopted; while for upper vias and metal layers with wider pattern sizes, the mature additive damascus patterning process is still used. Currently, ruthenium (Ru) is a better material for the subtractive bottom metal layer, but its chemical inertness and poor adhesion to materials with low dielectric constants make it prone to delamination due to weak adhesion, leading to problems such as high contact resistance and leakage. Furthermore, copper (Cu) metal vias used for interconnection typically require a combination of tantalum nitride (TaN) and tantalum (Ta) as a diffusion barrier layer. However, as the pattern density of the underlying metal layer increases, the diameter of the vias also decreases. This results in the diffusion barrier layer's thickness accounting for an increasingly larger proportion of the total Cu metal via diameter, and its resistance becoming a significant portion of the overall via resistance. This becomes a major reason why subsequent contact resistance and RC delay are difficult to further reduce. Therefore, it is necessary to investigate a process method that can significantly improve these problems. Summary of the Invention

[0003] The purpose of this application is to overcome the aforementioned problems in the prior art and to provide a semiconductor 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 a semiconductor structure, comprising: Provide substrate; A first metal layer is formed on the surface of the substrate, the material of the first metal layer including ruthenium; The first metal layer is patterned to form a first metal pattern; The surface of the first metal pattern is subjected to a first treatment by sequentially using plasma of hydrocarbon gas and vapor of coupling agent to form a monolayer adhesion promotion layer on the surface of the first metal pattern. A dielectric layer is formed on the surface of the substrate to cover the top of the first metal pattern. The dielectric layer is made of a low dielectric constant material and is bonded to the surface of the first metal pattern by the adhesion promoting layer. A through hole is formed on the surface of the dielectric layer, with the bottom of the hole connecting to the top of the first metal pattern; A second treatment is performed on the sidewalls of the via using nitrogen free radicals excited by metastable particles to modify the surface of the low dielectric constant material on the sidewalls of the via. A tantalum layer is formed on the sidewall of the through hole after the second treatment; A second metal layer electrically connected to the first metal pattern is filled into the through-hole within the tantalum layer.

[0005] In some embodiments, a third treatment is performed on the surface of the first metal pattern using plasma of the hydrocarbon gas to form a carbon-containing compound layer on the surface of the first metal pattern; a fourth treatment is performed on the surface of the first metal pattern having the compound layer using vapor of the coupling agent; selective grafting is achieved under infrared heating; and dehydration condensation is achieved by baking, thereby forming the adhesion-promoting layer on the surface of the first metal pattern. The first treatment includes the third treatment and the fourth treatment.

[0006] In some embodiments, the hydrocarbon gas includes CH4.

[0007] In some embodiments, the coupling agent comprises aminosilane or vinylsilane.

[0008] In some embodiments, the carbon-containing compound layer comprises an amorphous hydrocarbon film.

[0009] In some embodiments, during the third processing, a carrier gas is also added to the hydrocarbon gas. The flow rate of the mixture of the hydrocarbon gas and the carrier gas is 50 sccm to 200 sccm, the hydrocarbon gas flow rate: carrier gas flow rate = 1:3 to 1:5, the temperature is 10℃ to 30℃, the source power is 200W to 2000W, the bias power is 0W to 20W, the pressure is 15mTorr to 500mTorr, and the time is 3s to 20s.

[0010] In some embodiments, during the fourth treatment, the temperature of the coupling agent vapor is 40°C to 80°C, the infrared heating temperature is 80°C to 100°C, the infrared heating time is 1 minute to 10 minutes, the baking temperature is 150°C to 200°C, and the baking time is 5 minutes to 30 minutes.

[0011] In some embodiments, by performing the second treatment, nitrogen free radicals react with the bonding bonds on the surface of the low dielectric constant material on the sidewall of the through hole to form a nitrogen-rich surface layer, thereby modifying the surface of the low dielectric constant material on the sidewall of the through hole to improve the adhesion and interfacial diffusion blocking ability of the low dielectric constant material surface on the sidewall of the through hole.

[0012] In some embodiments, the low dielectric constant material includes silicon-based low dielectric constant materials.

[0013] 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 second 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.

[0014] In some embodiments, after forming the tantalum layer, the method further includes: performing a fifth treatment on the surface of the tantalum layer using hydrogen radicals excited by metastable particles to reduce the surface state density.

[0015] 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 fifth 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.

[0016] According to a second aspect of this application, embodiments of this application also provide a semiconductor structure obtained using a semiconductor structure fabrication method as provided in any of the embodiments of the first aspect above.

[0017] The embodiments of this application may have, or at least have, the following advantages: (1) By sequentially using hydrocarbon gas plasma and coupling agent vapor to perform a first treatment on the surface of the first metal pattern of ruthenium material, a monolayer adhesion-promoting layer can be formed on the surface of the first metal pattern, which can improve the adhesion between the first metal pattern and the dielectric layer of the low dielectric constant material. Specifically, by first using hydrocarbon gas plasma to perform a third treatment on the surface of the first metal pattern to form a carbon-containing compound layer on the surface of the first metal pattern, and then using coupling agent vapor to perform a fourth treatment on the surface of the first metal pattern with the compound layer, selective grafting is achieved under infrared heating, and dehydration condensation is achieved by baking. Thus, by forming an adhesion-promoting layer on the surface of the first metal pattern, an organic-inorganic interface bridge is established on the surface of the first metal pattern, which effectively improves the adhesion between the inert ruthenium material and the low dielectric constant material. Therefore, it is possible to achieve high-quality adhesion between the first metal pattern and the dielectric layer of the subsequently deposited low dielectric constant material, eliminating the previous problems of delamination caused by weak adhesion, resulting in high contact resistance and leakage.

[0018] (2) By using nitrogen free radicals excited by metastable particles to perform a second treatment on the sidewalls of the via, nitrogen free radicals (nitrogen atoms) can be adsorbed onto the surface of the low dielectric constant material on the sidewalls of the via at low energy to form dangling bonds (which can prevent nitrogen atoms from entering the interior of the low dielectric constant material and causing an increase in the dielectric constant (k) value). This optimizes the surface state (surface energy) and enhances the adhesion between tantalum and the low dielectric constant material on the sidewalls of the via. This facilitates a more continuous and uniform film formation of the tantalum layer, which acts as a diffusion barrier layer, on the sidewalls of the via, thereby reducing the contact resistance. Furthermore, by reacting the nitrogen free radicals with the bonding bonds on the surface of the low dielectric constant material on the sidewalls of the via, a dense nitrogen-rich surface layer is formed on the surface of the low dielectric constant material on the sidewalls of the via. 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, preventing the degradation of electrical properties (such as an increase in k value, increased leakage current, etc.). By performing a second treatment, nanoscale, uniform shallow surface modification of low dielectric constant materials is achieved, maintaining the low-k characteristics of the dielectric layer while constructing an effective sealing barrier.

[0019] (3) By using hydrogen free radicals excited by metastable particles to perform a fifth 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.

[0020] (4) By enhancing the adhesion and barrier diffusion ability of the via sidewall surface of the low dielectric constant material, the deposition quality of the tantalum layer is improved, so that only a single tantalum layer can be used to serve as a diffusion barrier layer, eliminating the need for tantalum nitride in the diffusion barrier layer (i.e., replacing the original diffusion barrier layer of TaN and Ta combination with a single Ta layer diffusion barrier layer). Therefore, the total thickness of the diffusion barrier layer can be reduced, thereby effectively reducing the proportion of the resistance of the diffusion barrier layer in the entire via, and thus significantly reducing the contact resistance and RC delay in the later stage.

[0021] The process steps in this application are highly compatible, which can enhance the adhesion of downstream metal interconnects, achieve lower resistance and interconnect reliability and stability, and well meet the technical requirements of advanced nodes.

[0022] Other advantages of this application will be described in the following detailed description. Attached Figure Description

[0023] Figure 1 This is a flowchart of a semiconductor structure fabrication method provided in a preferred embodiment of this application.

[0024] Figure 2 This is a schematic diagram of a first metal layer formed on the surface of a substrate, according to a preferred embodiment of this application.

[0025] Figure 3 This is a schematic diagram of a first metal pattern formed by patterning a first metal layer, which is a preferred embodiment of this application.

[0026] Figure 4 This is a schematic diagram of a preferred embodiment of the present application after forming a dielectric layer on the surface of a substrate that covers the top of a first metal pattern.

[0027] Figure 5 This is a schematic diagram of a via formed on the surface of a dielectric layer, provided as a preferred embodiment of this application.

[0028] Figure 6This 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 7 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 8 This is a schematic diagram of a preferred embodiment of the present application after the removal of the organic hydrophobic layer.

[0031] Figure 9 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 metal layer; 111. First metal pattern; 12. Dielectric layer; 13. Via; 14. Organic hydrophobic layer; 15. Tantalum layer; 16. Second metal layer. Detailed Implementation

[0033] To address the issues of high contact resistance and leakage caused by delamination due to the poor adhesion between ruthenium and subsequent low-dielectric-constant materials deposited after etching using the subtractive etching method for the bottom metal layer, ruthenium's chemical inertness leads to delamination. Furthermore, as the pattern density of the bottom metal layer increases, the diameter of the vias decreases. The thickness of the diffusion barrier layer, which combines tantalum nitride (TaN) and tantalum (Ta), becomes increasingly significant relative to the diameter of the Cu metal vias, further complicating the reduction of contact resistance and RC delay. This application provides a semiconductor structure fabrication method, including: Provide substrate; A first metal layer is formed on the surface of the substrate, the material of the first metal layer including ruthenium; The first metal layer is patterned to form a first metal pattern; The surface of the first metal pattern is subjected to a first treatment by sequentially using plasma of hydrocarbon gas and vapor of coupling agent to form a monolayer adhesion promotion layer on the surface of the first metal pattern. A dielectric layer is formed on the surface of the substrate to cover the top of the first metal pattern. The dielectric layer is made of a low dielectric constant material and is bonded to the surface of the first metal pattern by the adhesion promoting layer. A through hole is formed on the surface of the dielectric layer, with the bottom of the hole connecting to the top of the first metal pattern; A second treatment is performed on the sidewalls of the via using nitrogen free radicals excited by metastable particles to modify the surface of the low dielectric constant material on the sidewalls of the via. A tantalum layer is formed on the sidewall of the through hole after the second treatment; A second metal layer electrically connected to the first metal pattern is filled into the through-hole within the tantalum layer.

[0034] This application embodiment uses a first treatment on the surface of a first ruthenium metal pattern by sequentially using a hydrocarbon gas plasma and a coupling agent vapor. This forms a monolayer adhesion-promoting layer on the surface of the first metal pattern, establishing an organic-inorganic interface bridge. This effectively improves the adhesion between the chemically inert ruthenium material and the low-dielectric-constant material, thus enabling high-quality adhesion between the first metal pattern and the subsequently deposited low-dielectric-constant material dielectric layer. This eliminates the previous problems of delamination due to weak adhesion, resulting in high contact resistance and leakage. Furthermore, by using nitrogen free radicals excited by metastable particles to perform a second treatment on the sidewalls of the via, the adhesion and diffusion-blocking ability of the low-dielectric-constant material on the sidewall surface of the via are enhanced, improving the deposition quality of the tantalum layer. This allows a single tantalum layer to function as a diffusion barrier layer, eliminating the need for tantalum nitride in the diffusion barrier layer. Therefore, the total thickness of the diffusion barrier layer can be reduced, effectively lowering the proportion of the diffusion barrier layer's resistance in the overall via resistance, thereby significantly reducing the subsequent contact resistance and RC delay.

[0035] This application also provides a semiconductor structure obtained using the semiconductor structure preparation 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 a semiconductor 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 semiconductor 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.

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

[0040] Step S12: Form a first metal pattern on the surface of the substrate.

[0041] refer to Figure 2 In some embodiments, a deposition process may be used to form a first metal layer 11 on the surface of the substrate 10.

[0042] In some embodiments, the material of the first metal layer 11 includes ruthenium. For example, the material of the first metal layer 11 is ruthenium.

[0043] refer to Figure 3 In some embodiments, the first metal layer 11 is patterned, forming a first metal pattern 111 of ruthenium material on the surface of the substrate 10. Figure 3 The example shown is only exemplarily the case where one first metal pattern 111 is formed on the surface of substrate 10. It is understood that the number of first metal patterns formed is not limited to this. Figure 3 The diagram shows one first metal pattern 111. When there are multiple first metal patterns, there is a gap between any two adjacent first metal patterns.

[0044] In some embodiments, photolithography and dry etching processes can be used to form the first metal pattern 111 (i.e., the first metal pattern 111 can be formed using a "subtractive" method).

[0045] In some embodiments, a mixture of oxygen and chlorine gas can be used to perform plasma dry etching on the first metal layer 11 of the ruthenium material to form a first metal pattern 111.

[0046] In some embodiments, when performing plasma dry etching on the first metal layer 11, the flow rate ratio between the introduced chlorine gas and the oxygen gas is 0.1 to 0.2 (chlorine gas flow rate: oxygen flow rate = 1:10 to 2:10). For example, the chlorine gas to oxygen flow rate ratio can be 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.2, or any value between any two of the aforementioned flow rate ratios.

[0047] In some embodiments, when performing plasma dry etching on the first metal layer 11, the total flow rate of oxygen and chlorine is 30 sccm to 500 sccm. For example, the total flow rate of oxygen and chlorine can be 30 sccm, 40 sccm, 50 sccm, 60 sccm, 80 sccm, 100 sccm, 110 sccm, 150 sccm, 180 sccm, 200 sccm, 250 sccm, 270 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm, or 500 sccm, or any value between any two of the aforementioned flow rate values.

[0048] In some embodiments, when performing plasma dry etching on the first metal layer 11, the temperature is 100°C to 300°C. For example, the temperature can be 100°C, 110°C, 125°C, 150°C, 175°C, 190°C, 200°C, 250°C, 285°C, or 300°C, or any value between any two of the aforementioned temperature values.

[0049] In some embodiments, when performing plasma dry etching on the first metal layer 11, the source power is 1000W to 2000W. For example, the source power can be 1000W, 1100W, 1200W, 1300W, 1400W, 1500W, 1600W, 1700W, 1800W, 1900W, or 2000W, or any value between any two of the aforementioned power values.

[0050] In some embodiments, when performing plasma dry etching on the first metal layer 11, the bias power is 150W to 250W. For example, the bias power can be 150W, 160W, 170W, 180W, 190W, 200W, 210W, 220W, 230W, 240W, or 250W, or any value between any two of the aforementioned power values.

[0051] In some embodiments, when performing plasma dry etching on the first metal layer 11, the pressure is 10 mTorr to 100 mTorr. For example, the pressure can be 10 mTorr, 15 mTorr, 20 mTorr, 25 mTorr, 30 mTorr, 40 mTorr, 50 mTorr, 60 mTorr, 70 mTorr, 80 mTorr, 90 mTorr, or 100 mTorr, or any value between any two of the aforementioned pressure values.

[0052] Thus, through the coordinated control of the above-mentioned flow rate and flow ratio, temperature, power, pressure, etc., a first metal pattern 111 with a certain aspect ratio can be obtained.

[0053] Ruthenium is chemically inert, which can lead to poor adhesion with materials with low dielectric constants. Therefore, the adhesion between ruthenium and low dielectric constant materials can be improved through the following process method provided in the embodiments of this application, achieving high-quality adhesion between the first metal pattern 111 and the dielectric layer of the subsequently deposited low dielectric constant material. This eliminates the problems of delamination caused by weak adhesion, resulting in high contact resistance and leakage.

[0054] Step S13: The surface of the first metal pattern is subjected to a first treatment using plasma of hydrocarbon gas and vapor of coupling agent in sequence to form a monolayer adhesion promotion layer.

[0055] refer to Figure 3In some embodiments, a third treatment may be performed on the exposed surfaces (top and side surfaces) of the first metal pattern 111 using a plasma of hydrocarbon gas to form a carbon-containing compound layer (or a hydrocarbon-containing compound layer) (not shown) on the surface of the first metal pattern 111.

[0056] In some embodiments, the carbon-containing compound layer may include an amorphous hydrocarbon film.

[0057] In some embodiments, the hydrocarbon gas may include CH4, and an inert gas (e.g., He) may be used as the carrier gas. When CH4 is dissociated in plasma, it generates a series of active groups (e.g., CH3, CH2, CH radicals), which are the main precursors for carbon deposition. The hydrocarbon radicals and ions in the CH4 plasma can form a nanoscale-thick amorphous hydrocarbon film (aC:H) on the Ru surface of the first metal pattern 111 through adsorption, implantation, and cross-linking reactions.

[0058] Then, a fourth treatment can be performed on the surface of the first metal pattern 111 having the above-described compound layer using a vapor of a coupling agent. Selective grafting can be achieved under infrared heating, and a complete dehydration condensation reaction can be achieved through subsequent baking (which can be performed under a protective atmosphere, such as nitrogen) to stabilize the interface layer. This forms a monolayer adhesion-promoting layer (retaining C-containing dangling bonds) (not shown) on the surface of the first metal pattern 111. The first treatment includes the third and fourth treatments.

[0059] The core objective of the fourth treatment is to establish an organic-inorganic interface bridge on the surface of the first metallic pattern 111 of the Ru material, thereby achieving high-quality adhesion with the subsequently deposited dielectric layer of low-dielectric-constant material. Specifically, infrared heating generates infrared radiation that is preferentially absorbed by the Ru metal lines (first metallic pattern 111) (metals have high infrared absorption rates), enabling "self-aligned" grafting of the coupling agent vapor onto the carbon-containing compound layer. Furthermore, the heating promotes dehydration condensation between Ru-OH and Si-OH, forming stable Ru-O-Si covalent bonds.

[0060] In some embodiments, the coupling agent may include aminosilanes (such as APTES: 3-aminopropyltriethoxysilane) or vinylsilanes (such as VTES: vinyltriethoxysilane). The amino group can react with groups in the dielectric layer of the subsequent low-dielectric-constant material, and the vinyl group can participate in subsequent crosslinking, with terminal groups compatible with the low-dielectric-constant material (such as -NH2, -CH=CH2, -epoxy group, etc.), thereby acting as "dangling bonds" to chemically bond with the subsequently deposited low-dielectric-constant material (dielectric layer).

[0061] In some embodiments, during the third processing, the flow rate ratio between the introduced hydrocarbon gas and the carrier gas is: hydrocarbon gas flow rate : carrier gas flow rate = 1:3 to 1:5. For example, the flow rate ratio of hydrocarbon gas to carrier gas can be 1:3, 1:3.1, 1:3.5, 1:3.8, 1:4, 1:4.1, 1:4.5, 1:4.9, or 1:5, etc., and the flow rate ratio of the carrier gas can continuously vary between 3 and 5.

[0062] In some embodiments, during the third processing, the flow rate of the mixture of hydrocarbon gas and carrier gas is 50 sccm to 200 sccm. For example, the flow rate of the mixture can be 50 sccm, 60 sccm, 80 sccm, 100 sccm, 110 sccm, 120 sccm, 140 sccm, 160 sccm, 180 sccm, 190 sccm, or 200 sccm, or any value between any two of the aforementioned flow rates.

[0063] In some embodiments, the temperature during the third processing is between 10°C and 30°C. For example, the temperature may be 10°C, 11°C, 12°C, 15°C, 18°C, 20°C, 21°C, 22°C, 25°C, 28°C, 29°C, or 30°C, or any value between any two of the aforementioned temperature values.

[0064] In some embodiments, when performing the third processing, the source power is 200W to 2000W. For example, the source power may be 200W, 210W, 250W, 300W, 500W, 800W, 1000W, 1250W, 1500W, 1800W, or 2000W, or any value between any two of the aforementioned power values.

[0065] In some embodiments, when performing the third processing, the bias power is 0W to 20W. For example, the bias power can be 0W, 1W, 2W, 5W, 8W, 10W, 12W, 15W, 18W or 20W, or any value between any two of the aforementioned power values.

[0066] In some embodiments, the pressure during the third processing is 15 mTorr to 500 mTorr. For example, the pressure may be 15 mTorr, 20 mTorr, 50 mTorr, 70 mTorr, 90 mTorr, 100 mTorr, 200 mTorr, 300 mTorr, 400 mTorr, or 500 mTorr, or any value between any two of the aforementioned pressure values.

[0067] In some embodiments, the time for performing the third processing is 3s to 20s. For example, the time can be 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 15s, 17s, 19s, or 20s, or any value between any two of the aforementioned time values.

[0068] In some embodiments, during the fourth treatment, the temperature of the coupling agent vapor is 40°C to 80°C. For example, the temperature may be 40°C, 41°C, 42°C, 45°C, 48°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any value between any two of the aforementioned temperature values.

[0069] In some embodiments, when performing the fourth process, the infrared heating temperature is 80°C to 100°C. For example, the temperature can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, or 100°C, or any value between any two of the aforementioned temperature values.

[0070] In some embodiments, the infrared heating time during the fourth process is 1 to 10 minutes. For example, the time can be 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes, or any value between any two of the aforementioned time values.

[0071] In some embodiments, the baking temperature during the fourth processing is 150°C to 200°C. For example, the temperature may be 150°C, 151°C, 155°C, 158°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, or 200°C, or any value between any two of the aforementioned temperature values.

[0072] In some embodiments, the baking time during the fourth processing is 5 to 30 minutes. For example, the time may be 5 minutes, 6 minutes, 8 minutes, 10 minutes, 11 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 25 minutes, 29 minutes, or 30 minutes, or any value between any two of the aforementioned time values.

[0073] Thus, through the coordinated control of the above-mentioned flow ratio, flow rate, temperature, power, pressure, time, etc., a monolayer adhesion-promoting layer can be formed on the surface of the first metal pattern 111, which effectively improves the adhesion between the chemically inert ruthenium material and the low dielectric constant material.

[0074] In etching gas systems using oxygen and chlorine, non-volatile byproducts (RuO2 / RuCl) are easily generated during the etching process.x Residual ruthenium (such as linewidth roughness (LWR) and line edge roughness (LER)) results in poor sidewall roughness after etching, which can easily lead to short circuits or open circuits and affect overlay accuracy. Therefore, before performing the first treatment described above, the roughness of the sidewall of the first metal pattern 111 can be reduced by the following process method provided in the embodiments of this application to improve the above-mentioned problems and ensure that the processed first metal pattern 111 can be well connected with the upper metal via. Furthermore, by improving the roughness of the sidewall of the first metal pattern 111, the uniformity of the linewidth can be ensured, thus enabling the formation of a first metal pattern 111 with a higher aspect ratio, which is beneficial for reducing resistance.

[0075] refer to Figure 3 In some embodiments, after the first metal pattern 111 is formed, oxygen plasma (oxygen plasma) and hydrogen plasma (hydrogen plasma) can be recycled to perform a sixth treatment on the sidewalls of the first metal pattern 111 to reduce the roughness of the sidewalls of the first metal pattern 111, and hydrogen plasma is used for treatment in the last cycle.

[0076] By performing a sixth treatment based on a redox cycle on the sidewalls of the first metal pattern 111, oxygen plasma can be used to preferentially oxidize the ruthenium material on the surface of the protrusions present on the rough sidewalls of the first metal pattern 111. During oxidation using oxygen plasma, the ruthenium material on the sidewalls of the first metal pattern 111 reacts with the ruthenium material, oxidizing the surface ruthenium into volatile ruthenium tetroxide (RuO4) for removal. This removes at least part of the protrusions and produces a smoothing effect similar to "peak shaving and valley filling," smoothing the sidewalls of the first metal pattern 111. Simultaneously, the oxidation reaction may also generate solid ruthenium dioxide (RuO2), and once dense ruthenium dioxide is formed on the surface, the oxidation to ruthenium tetroxide reaction stops. Therefore, hydrogen plasma can be used to reduce ruthenium dioxide present on the sidewalls of the first metal pattern 111, reducing ruthenium dioxide to ruthenium. This is equivalent to "resetting" the surface chemical state, thus continuously providing a surface of fresh ruthenium material to be oxidized and avoiding the "self-limiting stagnation" phenomenon caused by the accumulation of ruthenium dioxide. By repeatedly using oxygen and hydrogen plasma in a redox cycle-based process, the roughness of the sidewalls of the first metal pattern 111 can be effectively reduced, making the sidewalls smoother and improving linewidth uniformity. This significantly reduces the risk of short circuits or open circuits, ensures good connection with the upper metal vias, and helps to improve the aspect ratio of the first metal pattern 111, thereby reducing resistance.

[0077] Step S14: Form a dielectric layer of low dielectric constant material on the surface of the substrate, cover the top of the first metal pattern, and bond it to the surface of the first metal pattern.

[0078] refer to Figure 4 In some embodiments, a deposition process can be used to form a dielectric layer 12 on the surface of the substrate 10, and the dielectric layer 12 has a sufficient deposition thickness to completely cover the top of the first metal pattern 111, so that the first metal pattern 111 is entirely located in the dielectric layer 12 and below the surface (top surface) of the dielectric layer 12. The height distance between the surface of the dielectric layer 12 and the top of the first metal pattern 111 is the height of the via to be formed subsequently.

[0079] When there are multiple first metal patterns, the deposited dielectric layer can completely fill the gap between adjacent first metal patterns, or fill it to form a seal between adjacent first metal patterns, so as to form an air gap between adjacent first metal patterns.

[0080] In some embodiments, the material of the dielectric layer 12 may include a low dielectric constant material (or an ultra-low dielectric constant material), etc. The low dielectric constant material dielectric layer 12 forms good adhesion to the surface of the first metal pattern 111 through an adhesion-promoting layer of a monolayer formed on the surface of the first metal pattern 111.

[0081] In some embodiments, the material of the dielectric layer 12 includes a silicon-based low dielectric constant material (or a silicon-based ultra-low dielectric constant material), such as SiCN, SiOCH, etc.

[0082] By performing a first treatment (a third treatment and a fourth treatment) on the surface of the first metal pattern 111, a monolayer adhesion-promoting layer is formed on the surface of the first metal pattern 111. An organic-inorganic interface bridge is established on the surface of the first metal pattern 111 of Ru material, achieving high-quality adhesion between it and the dielectric layer 12 of the low dielectric constant material. This effectively eliminates the problems of high contact resistance and leakage caused by the previous easy delamination due to weak adhesion between them.

[0083] Step S15: Form a through hole on the surface of the dielectric layer, with the bottom connected to the top of the first metal pattern.

[0084] refer to Figure 5 In some embodiments, patterning processes, such as photolithography and etching, can be used to form a through-hole 13 on the surface of the dielectric layer 12, with the bottom connected to the top of the first metal pattern 111.

[0085] A metal through-hole can be formed by filling the through-hole 13 with metal. The metal used to fill the through-hole 13 (the second metal layer) may include copper (Cu) or the like.

[0086] Step S16: Use nitrogen free radicals to perform a second treatment on the sidewalls of the via to modify the surface of the low dielectric constant material on the sidewalls of the via.

[0087] For back-end logic processes, the diffusion barrier layer in copper (Cu) vias typically uses a two-layer structure combining tantalum nitride (TaN) and tantalum (Ta). At advanced nodes, as the pattern density of the first metal pattern increases, the diameter of the via decreases, requiring increasingly thinner overall films of the TaN and Ta combination diffusion barrier layer. This results in poorer interfacial affinity of the diffusion barrier layer, often leading to pitting and peeling defects, causing low yields and making it difficult to further reduce 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 portion deposited at the bottom further increases contact resistance. These problems lead to severe 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 reliability and stability.

[0088] refer to Figure 6 In some embodiments, a vapor-phase self-assembly process can be used, and organic molecules containing thiols (-SH) or silicon (Si) can be used as precursors. A diluent gas can be added to selectively form a monolayer organic hydrophobic layer 14 on the exposed surface of the first metal pattern 111 at the bottom of the via 13. This layer is used to prevent tantalum layer deposition on the bottom of the via 13 by inhibiting tantalum layer deposition on the surface of the organic hydrophobic layer 14 during subsequent tantalum layer deposition, thereby avoiding an increase in the interfacial contact resistance between the upper and lower layers.

[0089] In some embodiments, the thiol-containing organic molecule may include alkyl thiols, such as n-octanethiol C8H17-SH.

[0090] 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.

[0091] In some embodiments, the diluent gas may include at least one of nitrogen, hydrogen, and inert gases (such as argon, helium, etc.).

[0092] refer to Figure 6In some embodiments, nitrogen radicals excited by metastable particles can be used to perform a second treatment on the sidewalls of the via 13 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.

[0093] In some embodiments, by performing a second 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 sidewall of the via 13 to form dangling bonds, which can optimize the surface state (surface energy). Therefore, it can enhance the adhesion between tantalum and the low dielectric constant material on the sidewall surface of the via 13, which is beneficial to improving the continuity and uniformity of the subsequently deposited tantalum layer on the sidewall of the via 13. This allows the tantalum layer to be deposited more continuously and uniformly on the surface-modified sidewall of the via 13, thereby reducing the contact resistance.

[0094] Furthermore, through a second 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 sidewall of the through-hole 13 at low energy, forming a nitrogen-rich surface layer on the surface of the low dielectric constant material on the sidewall of the through-hole 13. 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.).

[0095] 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 second treatment of the sidewalls of the through-hole 13 using nitrogen free radicals excited by metastable particles in this application embodiment is to allow nitrogen atoms to adsorb onto the surface of the low-k material on the sidewalls of the through-hole 13 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 thus avoiding a sharp increase in the overall k-value of the low-k material.

[0096] By performing a second treatment, the low-k material on the sidewall of the through-hole 13 is superficially modified, causing the reaction to occur only on the surface of the low-k material, forming an extremely thin "skin". This skin can seal the openings of the pores on the surface of the low-k material, but it does not change 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 medium layer 12 are maintained.

[0097] Furthermore, during the etching process to form the via 13, the plasma damages the low-k material on the sidewalls of the via 13, forming a "modified damage layer". This damage layer can be repaired and stabilized by using nitrogen free radicals excited by metastable particles to perform a second treatment on the sidewalls of the via 13.

[0098] In some embodiments, the nitrogen radicals required for the second 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.

[0099] In some embodiments, during the second 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.

[0100] In some embodiments, during the second 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 rate values.

[0101] In some embodiments, the temperature during the second 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.

[0102] In some embodiments, when performing the second processing, the source power is 1W to 100W. 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.

[0103] In some embodiments, the pressure during the second 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.

[0104] 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, 20s, 50s, 100s, 150s, 200s, 250s, 280s, or 300s, or any value between any two of the aforementioned time values.

[0105] In some embodiments, during the second processing, ion filtering is turned on and bias power is turned off.

[0106] 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 sidewall of via 13, enhancing the adhesion between the subsequently deposited tantalum and the low-dielectric-constant material on the sidewall surface of via 13, and constructing an effective sealing barrier.

[0107] Step S17: Form a tantalum layer on the sidewall of the through hole.

[0108] refer to Figure 7 In some embodiments, a deposition process can be used to form a tantalum layer 15 on the sidewalls of the surface-modified via 13 (the tantalum layer can also be deposited on the surface of the dielectric layer 12 other than the via 13). Figure 7 (The details are omitted here), allowing the deposited tantalum layer 15 to directly contact the low dielectric constant material on the sidewalls after the second surface treatment. Furthermore, by utilizing the monolayer organic hydrophobic layer 14 deposited on the bottom of the via 13, the deposition of the tantalum layer 15 on the bottom region of the via 13 occupied by the organic hydrophobic layer 14 can be suppressed, and the tantalum layer 15 can be selectively formed on the sidewalls of the via 13 outside the region occupied by the organic hydrophobic layer 14, thereby preventing the tantalum layer 15 from depositing on the surface of the first metal pattern 111 in the bottom region of the via 13 occupied by the organic hydrophobic layer 14.

[0109] In some embodiments, an atomic layer deposition process may be used to conformally form a tantalum layer 15 on the sidewall of the second-processed via 13.

[0110] By using nitrogen free radicals excited by metastable particles to perform a second surface modification on the low-dielectric-constant material on the sidewall of via 13, the adhesion between tantalum and the sidewall surface of the low-dielectric-constant material can be greatly enhanced. This allows the tantalum layer 15 to form a continuous and uniform film on the surface of the surface-modified low-dielectric-constant material on the sidewall, effectively eliminating film pits and peeling defects and improving yield. Furthermore, since the deposition quality of the tantalum layer 15 is significantly improved, it can play an effective diffusion barrier role. This allows the use of a single tantalum layer 15 to serve as the diffusion barrier layer independently, 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 resistance of via 13.

[0111] refer to Figure 8 In some embodiments, the organic hydrophobic layer 14 can be removed by thermal decomposition. By heating the substrate 10, the organic hydrophobic layer 14 can be heated and thermally decomposed at a high temperature (e.g., 300°C to 400°C), decomposing into gaseous small molecules (such as CH4, C2H4, H2S, etc.), which can be completely removed by vacuuming out the reaction chamber.

[0112] refer to Figure 8 In some embodiments, hydrogen radicals excited by metastable particles can be used to perform a fifth treatment on the surface of the tantalum layer 15 to reduce the surface state density.

[0113] A fifth treatment of the tantalum layer 15 using metastable particle-excited hydrogen radicals can remove oxide layers and impurities at low energy and low temperature, thus cleaning the surface of the tantalum layer 15. 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 15 can be... x The process reduces the tantalum layer 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.

[0114] In some embodiments, the hydrogen radicals required for the fifth 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.

[0115] In some embodiments, during the fifth process, argon gas is also added to the hydrogen gas to adjust its concentration. By adding argon gas to the hydrogen gas, excess hydrogen atoms on the surface of the tantalum layer 15 can be removed, preventing the formation of compounds due to excessive hydrogen atom content reacting with Ta.

[0116] In some embodiments, during the fifth 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.

[0117] In some embodiments, during the fifth 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.

[0118] In some embodiments, during the fifth process, the helium flow rate is 1000 sccm to 2000 sccm. For example, the helium flow rate can 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 rates.

[0119] In some embodiments, the temperature during the fifth process 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.

[0120] In some embodiments, when performing the fifth process, 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.

[0121] In some embodiments, the pressure during the fifth process 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.

[0122] In some embodiments, the time for performing the fifth process 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.

[0123] In some embodiments, during the fifth process, ion filtering is turned on and bias power is turned off.

[0124] By synergistically controlling the flow ratio, flow rate, temperature, source power, pressure, and time, lower energy and lower temperature hydrogen radicals can be obtained (achieving a completely isotropic reaction and reducing violent reactions on the structural surface or sputtering reactions on some sidewalls), thus achieving cleaning and passivation of the tantalum layer 15 surface and providing a more ideal nucleation surface for subsequent film deposition.

[0125] In some embodiments, during the fifth process, hydrogen free radicals can also be used to simultaneously clean and activate the exposed surface of the first metal pattern 111 on the bottom of the via 13, which can improve the electrical connection performance between the first metal pattern 111 material and the second metal layer material subsequently deposited in the via 13, and further reduce the interface contact resistance.

[0126] Step S18: Fill the through hole with a second metal layer that electrically connects to the first metal pattern.

[0127] refer to Figure 9In some embodiments, a deposition process can be used to fill the vias 13 within the tantalum layer 15 with a second metal layer 16, thus completely filling the vias 13. This allows the filled second metal layer 16 to directly contact the tantalum layer 15 after the fifth surface treatment, resulting in a denser, more uniform, and higher-quality film of the second metal layer 16, further reducing contact resistance. Furthermore, the filled second metal layer 16 directly contacts the surface of the first metal pattern 111 exposed at the bottom of the via 13, 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 interface contact quality between the second metal layer 16 and the first metal pattern 111, further reducing contact resistance.

[0128] In some embodiments, the material of the second metal layer 16 includes copper.

[0129] Subsequently, a planarization process (such as chemical mechanical polishing) can be used to remove excess metal material deposited on the surface of the dielectric layer 12, forming copper metal vias in the dielectric layer 12. An upper metal pattern can also be formed on the surface of the dielectric layer 12, as well as an upper dielectric layer covering the upper metal pattern.

[0130] By using nitrogen radicals excited by metastable particles to perform a second treatment on the sidewalls of via 13, the adhesion of tantalum and low-dielectric-constant materials to the sidewall surface is enhanced, improving the deposition quality of the tantalum layer 15 and constructing an effective sealing barrier that can effectively prevent Cu atoms from diffusing into the porous low-dielectric-constant material. A fifth treatment using hydrogen radicals excited by metastable particles to the surface of the tantalum layer 15 deposited on the sidewalls provides a more ideal nucleation surface for the deposition of the second metal layer 16, enabling the growth of a denser, more uniform, and higher-crystal-quality copper film. Therefore, using only a single tantalum layer 15 can independently serve as a diffusion barrier layer, reducing the total thickness of the diffusion barrier layer and its proportion of the overall resistance of the via 13. This reduces the downstream contact resistance and RC delay, effectively meeting the technical requirements at lower nodes. Furthermore, by performing a first treatment on the surface of the first metal pattern 111 of the ruthenium material, the first metal pattern 111 can be bonded to the dielectric layer 12 of the subsequently deposited low dielectric constant material with high quality, avoiding the increase of contact resistance and leakage current, and achieving lower resistance and interconnect reliability and stability.

[0131] In a second aspect, embodiments of this application also provide a semiconductor structure obtained using the semiconductor structure fabrication method provided in any of the embodiments of the first aspect described above.

[0132] refer to Figure 9In some embodiments, the semiconductor structure is disposed on a substrate 10. A first metal pattern 111 of ruthenium material is disposed on the surface of the substrate 10. A dielectric layer 12 of low dielectric constant material is also disposed on the surface of the substrate 10, and the first metal pattern 111 is located within the dielectric layer 12. The dielectric layer 12 of low dielectric constant material is bonded to the surface of the first metal pattern 111 by an adhesion-promoting layer (not shown) formed on the surface of the first metal pattern 111 as a monolayer. The surface of the dielectric layer 12 is higher than the top surface of the first metal pattern 111, and a through-hole 13 with its bottom connected to the top surface of the first metal pattern 111 is disposed on the surface of the dielectric layer 12. A tantalum layer 15 is disposed on the sidewall of the through-hole 13, and a second metal layer 16 directly electrically connected to the top surface of the first metal pattern 111 is filled within the tantalum layer 15, forming a metal through-hole connecting the first metal pattern 111.

[0133] In some embodiments, one side surface (outer surface) of the tantalum layer 15 is in direct contact with a low dielectric constant material on the sidewall of the via 13, and the other side surface (inner surface) of the tantalum layer 15 is in direct contact with a second metal layer 16 filling the via 13.

[0134] In some embodiments, a diffusion barrier layer is provided between the second metal layer 16 and the dielectric layer 12. The diffusion barrier layer is formed of a tantalum layer 15 (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 15, such as tantalum nitride layer).

[0135] In this process, the surface of the first metal pattern 111 undergoes a first treatment to form a monolayer adhesion-promoting layer. This layer bridges the organic-inorganic interface on the surface of the first metal pattern 111, effectively improving the adhesion between the chemically inert ruthenium material and the low-dielectric-constant material. This enables high-quality bonding between the first metal pattern 111 and the low-dielectric-constant dielectric layer 12, eliminating the previous problems of delamination due to weak adhesion, resulting in high contact resistance and leakage. The surface of the low-dielectric-constant material on the sidewall of the via 13 undergoes a second treatment to modify the surface, enhancing adhesion and reducing defect channels. The tantalum layer 15, acting as a diffusion barrier layer, is directly deposited on the surface of the surface-modified low-dielectric-constant material on the sidewall, improving the uniformity and density of the tantalum layer 15 deposition. Furthermore, the inner surface of the tantalum layer 15 undergoes a fifth treatment to reduce the surface state density, providing a more ideal nucleation surface. The second metal layer 16 is then deposited and filled effectively on the inner surface of the tantalum layer 15 after the surface state density has been reduced. Thus, by using only the tantalum layer 15 as the diffusion barrier layer, the total thickness of the diffusion barrier layer is reduced (compared to the overall film thickness of the diffusion barrier layer using a combination of TaN and Ta), thereby effectively reducing the proportion of the resistance of the diffusion barrier layer in the total resistance of the via 13, thereby reducing the downstream contact resistance and RC delay.

[0136] In some embodiments, during the fabrication of the semiconductor structure, by performing a sixth process based on an oxidation-reduction cycle using oxygen plasma and hydrogen plasma multiple times, the roughness of the sidewalls of the first metal pattern 111 can be effectively reduced, making the sidewalls of the first metal pattern 111 smoother, improving the linewidth uniformity, thereby significantly reducing the risk of short circuits or open circuits, ensuring good connection with the upper metal vias, and helping to improve the aspect ratio of the first metal pattern 111 to reduce resistance.

[0137] In some embodiments, when fabricating a semiconductor structure, by first forming a monolayer organic hydrophobic layer 14 on the exposed surface of the first metal pattern 111 at the bottom of the via 13, the deposition of the subsequent tantalum layer 15 on the bottom of the via 13 can be suppressed. After removing the organic hydrophobic layer 14, the second metal layer 16 subsequently filled in the via 13 can be directly electrically connected to the first metal pattern 111 below, thereby further reducing the contact resistance.

[0138] In a third aspect, embodiments of this application also provide a plasma processing apparatus for performing the semiconductor structure fabrication method corresponding to the above embodiments to form the semiconductor 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.

[0139] In other aspects, embodiments of this application also provide an electronic device, including a semiconductor structure obtained using the semiconductor 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.

[0140] In summary, this embodiment of the application, by sequentially using hydrocarbon gas plasma and coupling agent vapor to perform a first treatment on the surface of the first metal pattern 111 of ruthenium material, forms a monolayer adhesion-promoting layer on the surface of the first metal pattern 111. This enables high-quality adhesion between the first metal pattern 111 and the subsequently deposited low-dielectric-constant dielectric layer 12, eliminating the previous problems of delamination due to weak adhesion, resulting in high contact resistance and leakage. Furthermore, by using nitrogen free radicals excited by metastable particles to perform a second treatment on the sidewalls of the via 13, the adhesion and interfacial diffusion blocking ability of the low-dielectric-constant material on the sidewall surface of the via 13 can be enhanced, improving the deposition quality of the tantalum layer 15. This allows the single tantalum layer 15 to function as a diffusion barrier layer, eliminating the need for tantalum nitride in the diffusion barrier layer. Therefore, the total thickness of the diffusion barrier layer can be reduced, effectively reducing the proportion of the diffusion barrier layer's resistance in the overall resistance of the via 13, thereby significantly reducing the subsequent contact resistance and RC delay. The process steps in this application are highly compatible, which can enhance the adhesion of downstream metal interconnects, achieve lower resistance and interconnect reliability and stability, and well meet the technical requirements of advanced nodes.

[0141] 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 a semiconductor structure, characterized in that, include: Provide substrate; A first metal layer is formed on the surface of the substrate, the material of the first metal layer including ruthenium; The first metal layer is patterned to form a first metal pattern; The surface of the first metal pattern is subjected to a first treatment by sequentially using plasma of hydrocarbon gas and vapor of coupling agent to form a monolayer adhesion promotion layer on the surface of the first metal pattern. A dielectric layer is formed on the surface of the substrate to cover the top of the first metal pattern. The dielectric layer is made of a low dielectric constant material and is bonded to the surface of the first metal pattern by the adhesion promoting layer. A through hole is formed on the surface of the dielectric layer, with the bottom of the hole connecting to the top of the first metal pattern; A second treatment is performed on the sidewalls of the via using nitrogen free radicals excited by metastable particles to modify the surface of the low dielectric constant material on the sidewalls of the via. A tantalum layer is formed on the sidewall of the through hole after the second treatment; A second metal layer electrically connected to the first metal pattern is filled into the through-hole within the tantalum layer.

2. The semiconductor structure fabrication method according to claim 1, characterized in that, The surface of the first metal pattern is subjected to a third treatment using plasma of the hydrocarbon gas to form a carbon-containing compound layer on the surface of the first metal pattern. The surface of the first metal pattern having the compound layer is subjected to a fourth treatment using vapor of the coupling agent, selective grafting is achieved under infrared heating, and dehydration condensation is achieved by baking, thereby forming the adhesion promoting layer on the surface of the first metal pattern. The first treatment includes the third treatment and the fourth treatment.

3. The semiconductor structure fabrication method according to claim 2, characterized in that, The hydrocarbon gas includes CH4; and / or the coupling agent includes aminosilane or vinylsilane; and / or the carbon-containing compound layer includes an amorphous hydrocarbon film.

4. The semiconductor structure fabrication method according to claim 2, characterized in that, During the third process, a carrier gas is added to the hydrocarbon gas. The flow rate of the mixture of hydrocarbon gas and carrier gas is 50 sccm to 200 sccm, the ratio of hydrocarbon gas flow rate to carrier gas flow rate is 1:3 to 1:5, the temperature is 10℃ to 30℃, the source power is 200W to 2000W, the bias power is 0W to 20W, the pressure is 15mTorr to 500mTorr, and the time is 3s to 20s.

5. The semiconductor structure fabrication method according to claim 2, characterized in that, During the fourth treatment, the temperature of the coupling agent vapor is 40℃~80℃, the infrared heating temperature is 80℃~100℃, the infrared heating time is 1 minute~10 minutes, the baking temperature is 150℃~200℃, and the baking time is 5 minutes~30 minutes.

6. The semiconductor structure fabrication method according to claim 1, characterized in that, By performing the second treatment, nitrogen free radicals react with the bonding bonds on the surface of the low dielectric constant material on the sidewall of the via to form a nitrogen-rich surface layer, thereby modifying the surface of the low dielectric constant material on the sidewall of the via to improve the adhesion and interfacial diffusion blocking ability of the low dielectric constant material surface on the sidewall of the via; and / or, the low dielectric constant material includes a silicon-based low dielectric constant material.

7. The semiconductor structure fabrication method 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 second 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.

8. The semiconductor structure fabrication method according to claim 1, characterized in that, After the tantalum layer is formed, the process further includes: using hydrogen radicals excited by metastable particles to perform a fifth treatment on the surface of the tantalum layer to reduce the surface state density.

9. The semiconductor structure fabrication method according to claim 8, 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 fifth 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.

10. A semiconductor structure, characterized in that, Obtained using the semiconductor structure fabrication method as described in any one of claims 1-9.

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