Preparation method of gradient composite high-entropy alloy-graphene diffusion impervious layer

Abstract

The invention discloses a preparation method of a gradient composite high-entropy alloy-graphene diffusion barrier layer, and the method comprises the following steps: carrying out ultrasonic cleaning on a monocrystalline silicon substrate, depositing a titanium-vanadium-chromium-zirconium high-entropy alloy and graphene according to different proportions, in the heating process, forming a composite material by the titanium-vanadium-chromium-zirconium high-entropy alloy and the graphene, and carrying out heat treatment on the composite material to obtain the gradient composite high-entropy alloy-graphene diffusion barrier layer. A multi-layer diffusion barrier layer structure is obtained through layer-by-layer deposition, and finally a Cu electroplated layer is electroplated on the diffusion barrier layer. The multi-layer diffusion barrier layer structure obtained by the preparation method not only has a good barrier effect, but also has good thermal stability and strength, so that the multi-layer diffusion barrier layer structure has a good application prospect in a through silicon via (TSV) technology.

Description

Technical Field

[0001] This invention relates to the field of semiconductor process technology, and specifically to a method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer. Background Technology

[0002] In TSV (Through Silicon Via) technology, as chip integration density continues to increase, the performance requirements for interconnect materials become increasingly stringent. Ti, as a traditional barrier layer material, is widely used to block diffusion between Cu and Si due to its certain diffusion blocking ability and good compatibility with Cu and Si. However, in practical applications, its inherent defects have gradually become apparent. From a thermal stability perspective, when the chip operating temperature rises, the Ti barrier layer is prone to interfacial reactions with Cu and Si under high-temperature environments, forming unstable intermetallic compounds, leading to a decrease in barrier performance, causing Cu atom penetration, and thus affecting the long-term reliability of the device. In terms of electrical performance, Ti's high resistivity significantly increases the resistance of interconnect lines, generating additional power loss, limiting signal transmission speed, and hindering the high-speed development of chips. In terms of mechanical performance, the Ti barrier layer itself lacks strength and toughness, and is prone to cracking and delamination under thermal or mechanical stress, reducing the structural stability of the device. In addition, Ti is easily oxidized in air, and the resulting oxide layer changes its physicochemical properties, not only weakening the barrier effect but also potentially introducing impurities, affecting chip performance.

[0003] Therefore, there is an urgent need to develop a high-performance TSV barrier layer material with good thermal stability, low resistivity, and good barrier effect to meet the needs of chip technology development. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer. The diffusion barrier layer prepared by this method has good thermal stability, low resistivity, and good barrier effect.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer, comprising the following steps:

[0006] (1) Ultrasonic cleaning is performed on a single-crystal silicon substrate with depositable regions, and the substrate is dried after thorough cleaning.

[0007] (2) High-entropy alloy targets were prepared by vacuum arc melting and the melting was repeated five times to ensure uniform composition.

[0008] (3) Install the high-entropy alloy target on the DC magnetron sputtering target position and the graphene target on the RF magnetron sputtering target position. Adjust the target-substrate distance, with the high-entropy alloy target between 70-90 mm and the graphene target between 95-110 mm.

[0009] (4) Using an alternating sputtering co-sputtering mode, sputter the high-entropy alloy for 30-32 s, then sputter the graphene for 4-5 s, repeating this cycle 20 times in the pre-deposition area of ​​the silicon substrate to obtain a high-entropy alloy-low graphene content sputtered deposition layer; perform a first heat treatment on the substrate, with the vacuum degree inside the furnace between 4 × 10⁻⁶ and 10⁻⁶. -5 Pa-6×10 -5 Between Pa, the temperature is held at 400-450℃ for 30-40 minutes and then cooled in the furnace to obtain a high-entropy alloy-low graphene content diffusion barrier layer.

[0010] (5) Using an alternating sputtering co-sputtering mode, sputter the high-entropy alloy for 20-21 s, then sputter the graphene for 7-8 s, repeating this cycle 25 times on the surface of the high-entropy alloy-low graphene content diffusion barrier layer to obtain a high-entropy alloy-medium graphene content sputtered deposition layer; perform a second heat treatment on the substrate, with the vacuum degree inside the furnace between 1×10⁻⁶. -5 Pa-2×10 -5 Between Pa, the temperature is held at 500-550℃ for 40-50 min, and nitrogen is used for protective cooling at a flow rate of 10-15 sccm to obtain a high-entropy alloy-medium graphene content diffusion barrier layer.

[0011] (6) Using an alternating sputtering co-sputtering mode, sputter the high-entropy alloy for 14-16 s, then sputter the graphene for 10-11 s, repeating this cycle 30 times on the surface of the high-entropy alloy-medium graphene content diffusion barrier layer to obtain a high-entropy alloy-high graphene content sputtered deposition layer; perform a third heat treatment on the substrate, with the vacuum degree inside the furnace between 5 × 10⁻⁶ and 10⁻⁶. -6 Pa-6×10 -6 Between Pa, a gradient cooling method was used to cool the material at 5℃ / min from 600℃ to 400℃, and then at 10℃ / min from 400℃ to room temperature to obtain a high-entropy alloy-high graphene content diffusion barrier layer.

[0012] (7) A Cu electroplating layer is formed on the surface of the high-entropy alloy-high graphene content diffusion barrier layer to obtain a copper interconnect structure.

[0013] In an optional embodiment, the content of low graphene is between 1.0-2.4 vol%, the content of medium graphene is between 2.5-4.0 vol%, and the content of high graphene is between 4.1-5.0 vol%.

[0014] In an optional implementation, the sputtering power of the high-entropy alloy target is between 130-220W, and the sputtering power of the graphene target is between 40-70W.

[0015] In an optional implementation, the sputtering bias is between -150V and -100V.

[0016] In optional embodiments, the thickness of the high-entropy alloy-low graphene content sputtered deposition layer is between 80-100 nm, the thickness of the high-entropy alloy-medium graphene content sputtered deposition layer is less than 120-140 nm, and the thickness of the high-entropy alloy-high graphene content sputtered deposition layer is between 140-160 nm.

[0017] In an optional embodiment, in step (7), the substrate is pretreated before electroplating by using Ar plasma to perform plasma cleaning at a power of 80-100w, a pressure of 0.8-1.0Pa, and a time of 8-10min.

[0018] In an optional embodiment, in step (7), the electrolyte composition may be CuSO4·5H2O 230g / L, H2SO4 60g / L, Cl - 80ppm, PEG-8000 1g / L, polyetheramine 0.5g / L.

[0019] In an optional implementation, in step (7), the electroplating temperature is not lower than 25°C.

[0020] In an optional implementation, in step (7), the thickness of the electroplated Cu is not less than 10 μm.

[0021] In an optional embodiment, the high-entropy alloy includes at least four of the following: titanium, vanadium, chromium, zirconium, tantalum, molybdenum, niobium, aluminum, and nickel.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. In TSV copper interconnect technology, traditional Ti barrier layers suffer from poor thermal stability, high resistivity, weak mechanical properties, and susceptibility to oxidation, severely limiting chip performance and reliability. Gradient high-entropy alloy-graphene diffusion barrier layers, however, achieve performance optimization through a three-layer structure design: the bottom layer is primarily composed of a high-entropy alloy with a small amount of graphene to enhance thermal stability; the middle layer adds graphene to form a nano-network, strengthening the barrier effect; and the top layer, with its high graphene content, reduces surface energy and promotes Cu electroplating.

[0024] 2. Compared with the Ti barrier layer, the thermal stability (failure temperature) of this gradient structure is improved from 450℃ to 689℃. After annealing at 400℃, the average growth thickness of the interface IMC is reduced from 52mm to 8mm, and the resistivity is reduced from 42μΩ·cm to 28μΩ·cm. It also has stronger oxidation resistance, making it an ideal choice for high-performance TSV interconnects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the Si substrate in Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the preparation of a high-entropy alloy-low graphene content diffusion barrier layer in Example 1 of the present invention.

[0028] Figure 3 This is a schematic diagram of the preparation of a high-entropy alloy-medium graphene content diffusion barrier layer in Example 1 of the present invention;

[0029] Figure 4 This is a schematic diagram of the preparation of a high-entropy alloy-high graphene content diffusion barrier layer in Experimental Example 1 of the present invention;

[0030] Figure 5 This is a schematic diagram of copper electroplating in Embodiment 1 of the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0033] This application provides a gradient composite high-entropy alloy-graphene diffusion barrier layer, the steps of which include:

[0034] A single-crystal Si substrate with depositable regions is placed in acetone, anhydrous ethanol, and deionized water in sequence for ultrasonic cleaning. Specifically, it is first placed in acetone for 13-17 minutes of ultrasonic cleaning (e.g., 13 min, 14 min, 15 min, 16 min, 17 min, etc., without specific limitation), then placed in anhydrous ethanol for 13-17 minutes of ultrasonic cleaning (e.g., 13 min, 14 min, 15 min, 16 min, 17 min, etc., without specific limitation), and finally placed in deionized water for 8-12 minutes of ultrasonic cleaning (e.g., 8 min, 9 min, 10 min, 11 min, 12 min, etc., without specific limitation). After thorough cleaning, it is placed in a vacuum oven at 110-130℃ and baked for 30-40 minutes (e.g., 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, etc., without specific limitation) to ensure that the surface is completely dry.

[0035] High-entropy alloy targets were prepared by vacuum arc melting, and the melting was repeated five times to ensure uniform composition. The high-entropy alloy has a face-centered cubic structure.

[0036] The high-entropy alloy target is installed at the DC magnetron sputtering target position, and the graphene target is installed at the RF magnetron sputtering target position. The target-substrate distance is adjusted so that the high-entropy alloy target is between 70-90mm (e.g., 70mm, 75mm, 80mm, 85mm, 90mm, etc., which are not specifically limited here), and the graphene target is between 95-110mm (e.g., 95mm, 100mm, 105mm, 110mm, etc., which are not specifically limited here).

[0037] A high-entropy alloy-low graphene content sputtered deposition layer was prepared by using an alternating sputtering co-sputtering mode. The high-entropy alloy was sputtered for 30-32s (e.g., 30s, 31s, 32s, etc., which are not specifically limited here), and then the graphene was sputtered for 4-5s (e.g., 4s, 5s, etc., which are not specifically limited here). This cycle was repeated 20 times in the pre-deposition region of the silicon substrate to obtain the high-entropy alloy-low graphene content sputtered deposition layer.

[0038] The substrate undergoes its first heat treatment, with the vacuum level inside the furnace between 4 × 10⁻⁶. -5 Pa-6×10 -5 Pa (e.g. 4 × 10) -5 Pa, 5×10 -5 Pa, 6×10 -5The high-entropy alloy-low graphene content diffusion barrier layer is obtained by holding the material at 400-450℃ (e.g., 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, etc., without specific limitation) for 30-40 minutes (e.g., 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes, 40 minutes, etc., without specific limitation) and then cooling it in the furnace.

[0039] To prepare a high-entropy alloy-medium graphene content sputtered deposition layer, a co-sputtering mode with alternating sputtering is used. The high-entropy alloy is sputtered for 20-21 seconds (e.g., 20s, 21s, etc., which are not specifically limited here), and then graphene is sputtered for 7-8 seconds (e.g., 7s, 8s, etc., which are not specifically limited here). This cycle is repeated 25 times on the surface of the high-entropy alloy-low graphene content diffusion barrier layer to obtain a high-entropy alloy-medium graphene content sputtered deposition layer.

[0040] The substrate undergoes a second heat treatment, with the vacuum level inside the furnace between 1×10⁻⁶. -5 Pa-2×10 -5 Pa (e.g., 1×10) -5 Pa, 2×10 -5 The high-entropy alloy-medium graphene content diffusion barrier layer is obtained by holding the temperature at 500-550℃ (e.g., 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, etc., without specific limitation) for 40-50 minutes (e.g., 40 minutes, 42 minutes, 44 minutes, 46 minutes, 48 ​​minutes, 50 minutes, etc., without specific limitation) with nitrogen protection cooling at a flow rate of 10-15 sccm (e.g., 10 sccm, 11 sccm, 12 sccm, 13 sccm, 14 sccm, 15 sccm, etc., without specific limitation) between Pa and 500-550℃ for 40-50 minutes (e.g., 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, etc., without specific limitation) and holding it at 500-550℃ for 40-50 minutes (e.g., 40 minutes, 42 minutes, 44 minutes, 46 minutes, 48 ​​minutes, 50 minutes, etc., without specific limitation) ...

[0041] A high-entropy alloy-high graphene content sputtered deposition layer was prepared by using an alternating sputtering co-sputtering mode. The high-entropy alloy was sputtered for 14-16 s (e.g., 14 s, 15 s, 16 s, etc., which are not specifically limited here), and then the graphene was sputtered for 10-11 s (e.g., 10 s, 11 s, etc., which are not specifically limited here). This cycle was repeated 30 times on the surface of the high-entropy alloy-medium graphene content diffusion barrier layer to obtain the high-entropy alloy-high graphene content sputtered deposition layer.

[0042] The substrate undergoes a third heat treatment, with the vacuum level inside the furnace between 5 × 10⁻⁶. -6 Pa-6×10 -6 Pa (e.g., 5 × 10) -6 Pa, 6×10 -6A high-entropy alloy-high graphene content diffusion barrier layer was obtained by using gradient cooling at 5℃ / min between 600℃ and 400℃, and at 10℃ / min between 400℃ and room temperature.

[0043] To prepare a Cu electroplated layer, the substrate is first pretreated with plasma cleaning, and then the Cu layer is electroplated using an electrolyte.

[0044] In optional embodiments, the content of low-grade graphene is between 1.0-2.4 vol% (e.g., 1.0 vol%, 1.2 vol%, 1.4 vol%, 1.6 vol%, 1.8 vol%, 2.0 vol%, 2.2 vol%, 2.4 vol%, etc., which are not specifically limited here), the content of medium-grade graphene is between 2.5-4.0 vol% (e.g., 2.5 vol%, 2.6 vol%, 2.8 vol%, 3.0 vol%, 3.2 vol%, 3.4 vol%, 3.6 vol%, 3.8 vol%, 4.0 vol%, etc., which are not specifically limited here), and the content of high-grade graphene is between 4.1-5.0 vol% (e.g., 4.1 vol%, 4.2 vol%, 4.4 vol%, 4.6 vol%, 4.8 vol%, 5.0 vol%, etc., which are not specifically limited here).

[0045] In an optional embodiment, the sputtering power of the high-entropy alloy target is between 130-220W (e.g., 130W, 140W, 150W, 160W, 170W, 180W, 190W, 200W, 210W, 220W, etc., which are not specifically limited here), and the sputtering power of the graphene target is between 40-70W (e.g., 40W, 50W, 60W, 70W, etc., which are not specifically limited here).

[0046] In an optional implementation, the sputtering bias voltage should be between -150V and -100V (e.g., -150V, -140V, -130V, -120V, -110V, -100V, etc., which are not specifically limited here).

[0047] In optional embodiments, the thickness of the high-entropy alloy-low graphene sputtering content deposited layer should be between 80-100 nm, the thickness of the high-entropy alloy-medium graphene sputtering content deposited layer should be less than 120-140 nm (e.g., 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, etc., which are not specifically limited here), and the thickness of the high-entropy alloy-high graphene sputtering content deposited layer should be between 140-160 nm (e.g., 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, etc., which are not specifically limited here).

[0048] In an optional embodiment, the pretreatment can be performed using Ar plasma at a power of 80-100W (e.g., 80W, 85W, 60W, 70W, etc., which are not specifically limited here), a pressure of 0.8-1.0Pa (e.g., 0.8Pa, 0.9Pa, 1.0Pa, etc., which are not specifically limited here), and a time of 8-10min (e.g., 8min, 9min, 10min, etc., which are not specifically limited here).

[0049] In an optional embodiment, the electrolyte composition may be CuSO4·5H2O 230g / L, H2SO4 60g / L, Cl - 80ppm, PEG-8000 1g / L, polyetheramine 0.5g / L.

[0050] In an optional implementation, the electroplating temperature is not lower than 25°C.

[0051] In an optional embodiment, the thickness of the electroplated Cu is not less than 10 μm.

[0052] In an optional embodiment, the high-entropy alloy includes at least four of the following: titanium, vanadium, chromium, zirconium, tantalum, molybdenum, niobium, aluminum, and nickel.

[0053] This invention provides a gradient composite high-entropy alloy-graphene diffusion barrier layer. The unique multi-principal structure of the high-entropy alloy endows it with excellent thermal stability. Under high-temperature environments, the high mixing entropy of atoms inhibits the formation of intermetallic compounds, thereby maintaining a stable barrier effect. It also has low resistivity, which can significantly reduce the resistance of interconnect circuits, reduce power loss, and ensure high-speed operation of chips. In terms of mechanical properties, the high-entropy alloy possesses high strength, high toughness, and good fatigue resistance, enabling it to withstand complex stress environments and enhance the structural reliability of devices. The introduction of graphene further improves the overall performance of the composite material. Its ultra-high mechanical strength and good flexibility can work synergistically with the high-entropy alloy to resist external stresses. Simultaneously, the two-dimensional structure of graphene can effectively hinder atomic diffusion, forming a synergistic barrier effect with the high-entropy alloy, greatly improving the performance of the barrier layer. The high-entropy alloy-graphene composite material formed by the combination of these two materials is expected to become a new generation of high-performance TSV barrier layer materials, providing strong support for the development of chip technology.

[0054] The present invention will be further described in detail below with reference to the embodiments.

[0055] Example 1

[0056] The single-crystal Si substrate was ultrasonically cleaned sequentially in acetone, anhydrous ethanol, and deionized water (resistivity 18.2 MΩ·cm) for 15 min, 15 min, and 10 min, respectively, and then baked in a vacuum oven at 120℃ for 35 min. A schematic diagram of the Si substrate is shown below. Figure 1 As shown.

[0057] High-entropy alloy targets (Ti-V-Cr-Zr) were prepared by vacuum arc melting, and the mixture was repeatedly melted five times to ensure uniform composition.

[0058] The Ti-V-Cr-Zr high-entropy alloy target was sputtered by DC with a power of 180W and a target-substrate distance of 80mm.

[0059] The graphene target was sputtered using radio frequency (RF) with a power of 60W and a target-substrate distance of 100mm.

[0060] First, the high-entropy alloy was sputtered for 31 seconds, then graphene was sputtered for 4.5 seconds. This process was repeated 20 times to obtain a high-entropy alloy-low graphene content sputtered deposition layer with a graphene content of 1.8 vol%.

[0061] At a vacuum degree of 5×10 -5 The high-entropy alloy-low graphene content sputtered deposition layer was held at 420℃ for 35 min in the furnace of Pa, and then cooled with the furnace to obtain a high-entropy alloy-low graphene content diffusion barrier layer, as shown in the schematic diagram. Figure 2 As shown.

[0062] After sputtering the high-entropy alloy for 20.5 s, graphene was sputtered for 7.5 s, and the cycle was repeated 25 times to obtain a high-entropy alloy sputtered deposition layer with a graphene content of 3.2 vol%.

[0063] At a vacuum degree of 1.5 × 10 -5 The high-entropy alloy-medium graphene content sputtered deposition layer was held at 520℃ for 45 min in a Pa furnace and cooled with nitrogen at a flow rate of 12 sccm to obtain a high-entropy alloy-medium graphene content diffusion barrier layer, as shown in the schematic diagram. Figure 3 As shown.

[0064] After sputtering the high-entropy alloy for 15 seconds, graphene was sputtered for 10.5 seconds. This process was repeated 30 times to achieve a thickness of 150 nm, resulting in a high-entropy alloy-high graphene content sputtered deposition layer with a graphene content of 4.6 vol%.

[0065] At a vacuum degree of 5.5 × 10 -6 The material was held at a temperature of 600℃ in a furnace, then cooled at a rate of 5℃ / min from 600℃ to 400℃, and then cooled to room temperature at a rate of 10℃ / min to obtain a high-entropy alloy-high graphene content diffusion barrier layer, as shown in the schematic diagram. Figure 4 As shown.

[0066] To prepare a Cu electroplated layer, the substrate was pretreated with Ar plasma cleaning at a power of 90 W, a pressure of 0.9 Pa, and a time of 9 min. After pretreatment, CuSO4·5H2O (230 g / L), H2SO4 (60 g / L), and Cl were used. - An electrolyte solution containing 80 ppm, PEG-8000 1 g / L, and polyetheramine 0.5 g / L was used at 28°C with a flow rate of 2 A / dm³. 2 Electrolysis was performed at a current density to obtain a 15μm copper column, as shown in the schematic diagram. Figure 5 As shown.

[0067] Example 2

[0068] The single-crystal Si substrate was ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water (resistivity 18.2 MΩ·cm) for 15 min, 15 min, and 10 min respectively, and then baked in a vacuum oven at 120℃ for 35 min.

[0069] High-entropy alloy targets (Ti-Zr-Ta-Mo) were prepared by vacuum arc melting, and the mixture was repeatedly melted five times to ensure uniform composition.

[0070] The Ti-Zr-Ta-Mo high-entropy alloy target was sputtered by DC with a power of 200W and a target-substrate distance of 75mm.

[0071] The graphene target was sputtered using radio frequency (RF) with a power of 50W and a target-to-substrate distance of 98mm.

[0072] First, the high-entropy alloy was sputtered for 30 seconds, then graphene was sputtered for 4 seconds. This process was repeated 20 times, resulting in a thickness of 85 nm. This yielded a high-entropy alloy-low-graphene content sputtered deposition layer with a graphene content of 1.5 vol%.

[0073] At a vacuum degree of 4.5 × 10 -5 The high-entropy alloy-low graphene content sputtered deposition layer was held at 430℃ for 38 min in the furnace of Pa and then cooled with the furnace to obtain the high-entropy alloy-low graphene content diffusion barrier layer.

[0074] After sputtering the high-entropy alloy for 21 seconds, graphene was sputtered for 8 seconds, and the cycle was repeated 25 times to obtain a high-entropy alloy-medium graphene sputtered deposition layer with a graphene content of 3.8 vol%.

[0075] At a vacuum degree of 1.8 × 10 -5 The high-entropy alloy-medium graphene content sputtered deposition layer was held at 530℃ for 42 min in a Pa furnace and cooled with nitrogen flow rate of 14 sccm to obtain the high-entropy alloy-medium graphene content diffusion barrier layer.

[0076] After sputtering the high-entropy alloy for 14 seconds, graphene was sputtered for 11 seconds. This process was repeated 30 times, resulting in a thickness of 155 nm, to obtain a high-entropy alloy-high graphene content sputtered deposition layer with a graphene content of 4.9 vol%.

[0077] At a vacuum degree of 6×10 -6 The material is kept at a constant temperature in a furnace, cooled at a rate of 5°C / min from 600°C to 400°C, and then cooled to room temperature at a rate of 10°C / min to obtain a high-entropy alloy-high graphene content diffusion barrier layer.

[0078] To prepare a Cu electroplated layer, the substrate was pretreated with Ar plasma cleaning at a power of 85 W, a pressure of 0.9 Pa, and a time of 9 min. After pretreatment, CuSO4·5H2O (230 g / L), H2SO4 (60 g / L), and Cl were used. - An electrolyte solution containing 80 ppm, PEG-8000 1 g / L, and polyetheramine 0.5 g / L was used at 30°C with a flow rate of 2 A / dm³. 2 Electrolysis was performed at a current density to obtain a 15μm copper column.

[0079] Example 3

[0080] The difference between Example 3 and Example 1 is that the composition of the high-entropy alloy target is adjusted to Ti-Nb-Al-Ni, while other process parameters are the same as in Example 1.

[0081] Example 4

[0082] The difference between Example 4 and Example 1 is that the composition of the high-entropy alloy target is adjusted to V-Cr-Zr-Ta, while other process parameters are the same as in Example 1.

[0083] Example 5

[0084] The difference between Example 5 and Example 1 is that the composition of the high-entropy alloy target is adjusted to Cr-Zr-Ta-Mo, while other process parameters are the same as in Example 1.

[0085] Example 6

[0086] The difference between Example 6 and Example 1 is that the composition of the high-entropy alloy target is adjusted to Ti-V-Cr-Zr-Ta, while other process parameters are the same as in Example 1.

[0087] Example 1

[0088] The difference between Comparative Example 1 and Example 1 is that the target material composition was adjusted to Ti, while other process parameters were the same as in Example 1.

[0089] Comparative Example 2

[0090] The difference between Comparative Example 2 and Example 1 is that the composition of the high-entropy alloy target is the same as that of Example 1, only a single layer of high-entropy alloy-graphene diffusion barrier layer is prepared, and other process parameters are the same as those in Example 1.

[0091] Comparative Example 3

[0092] The difference between Comparative Example 3 and Example 1 is that the composition of the high-entropy alloy target is the same as that of Example 1, only a single-layer high-entropy alloy diffusion barrier layer is prepared, and other process parameters are the same as those of Example 1.

[0093] Experimental Example 1

[0094] Resistance tests were performed on Examples 1-3 and Comparative Examples 1-3 under the same conditions to detect the electrical connection performance of the barrier layer.

[0095] Table 1 Average Resistivity

[0096] Barrier layer material Resistivity (μΩ·cm) Example 1 32.5 Example 2 29.8 Example 3 35.7 Example 4 30.4 Example 5 31.1 Example 6 29.2 Comparative Example 1 25.3 Comparative Example 2 38.6 Comparative Example 3 31.2

[0097] As can be seen from Table 1, the electrical performance of the gradient composite high-entropy alloy-graphene diffusion barrier layer is better than that of the traditional diffusion barrier layer.

[0098] Experiment Example 2

[0099] Examples 1-3 and Comparative Examples 1-3 were annealed at 400°C for 1 hour, and the thickness of the interfacial IMC layer was observed. The smaller the thickness, the better the blocking effect.

[0100] Table 2 Average Growth Thickness of IMC

[0101] Barrier layer material IMC layer thickness (nm) Example 1 12 Example 2 8 Example 3 15 Example 4 13 Example 5 11 Example 6 13 Comparative Example 1 52 Comparative Example 2 25 Comparative Example 3 32

[0102] As can be seen from Table 2, the blocking effect of the gradient composite high-entropy alloy-graphene diffusion barrier layer is much better than that of the Ti barrier layer, about 4.3 times better. The high-entropy alloy significantly inhibits the growth of the IMC layer.

[0103] Experimental Example 3

[0104] Examples 1-3 and Comparative Examples 1-3 were subjected to heat treatment, and their failure temperatures were tested.

[0105] Table 2 Average failure temperature of diffusion barrier layer

[0106] Barrier layer material Failure temperature (°C) Example 1 651 Example 2 689 Example 3 632 Example 4 665 Example 5 647 Example 6 692 Comparative Example 1 457 Comparative Example 2 556 Comparative Example 3 583

[0107] Table 3 shows that the gradient distribution of graphene and the high-entropy alloy work together to raise the failure temperature to 689℃, which is 52% higher than that of the traditional Ti layer.

[0108] In summary, the method for preparing the diffusion barrier layer of the three-dimensional encapsulation of the present invention produces a diffusion barrier layer that does not generate Kirkendal voids, exhibits good thermal stability, high adhesion to the substrate, and good mechanical properties such as shear and tensile strength. The IMC layer (intermetallic compound) shows minimal thickness change over time, significantly extending its service life. Furthermore, the preparation method is simple, does not require large-scale equipment such as PVD, effectively saves costs, and is easy to mass-produce.

[0109] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer, characterized in that, Includes the following steps: (1) Ultrasonic cleaning is performed on a single-crystal silicon substrate with depositable regions, and the substrate is dried after thorough cleaning. (2) High-entropy alloy targets were prepared by vacuum arc melting and the melting was repeated five times to ensure uniform composition. (3) Install the high-entropy alloy target on the DC magnetron sputtering target position and the graphene target on the RF magnetron sputtering target position. Adjust the target-substrate distance, with the high-entropy alloy target between 70-90 mm and the graphene target between 95-110 mm. (4) Using the co-sputtering mode of alternating sputtering, the high-entropy alloy is sputtered for 30-32s, and then the graphene is sputtered for 4-5s. This process is repeated 20 times in the pre-deposition area of ​​the silicon substrate to obtain a high-entropy alloy-low graphene content sputtered deposition layer. The substrate undergoes its first heat treatment, with the vacuum level inside the furnace between 4 × 10⁻⁶. -5 Pa-6×10 -5 Between Pa, the temperature is held at 400-450℃ for 30-40 minutes and then cooled in the furnace to obtain a high-entropy alloy-low graphene content diffusion barrier layer. (5) Using an alternating sputtering co-sputtering mode, sputter the high-entropy alloy for 20-21 s, then sputter the graphene for 7-8 s, repeating this cycle 25 times on the surface of the high-entropy alloy-low graphene content diffusion barrier layer to obtain a high-entropy alloy-medium graphene content sputtered deposition layer; perform a second heat treatment on the substrate, with the vacuum degree inside the furnace between 1×10⁻⁶. -5 Pa-2×10 -5 Between Pa, the temperature is held at 500-550℃ for 40-50 min, and nitrogen is used for protective cooling at a flow rate of 10-15 sccm to obtain a high-entropy alloy-medium graphene content diffusion barrier layer. (6) Using an alternating sputtering co-sputtering mode, sputter the high-entropy alloy for 14-16 s, then sputter the graphene for 10-11 s, repeating this cycle 30 times on the surface of the high-entropy alloy-medium graphene content diffusion barrier layer to obtain a high-entropy alloy-high graphene content sputtered deposition layer; perform a third heat treatment on the substrate, with the vacuum degree inside the furnace between 5 × 10⁻⁶ and 10⁻⁶. -6 Pa-6×10 -6 Between Pa, a gradient cooling method was used to cool the material at 5℃ / min from 600℃ to 400℃, and then at 10℃ / min from 400℃ to room temperature to obtain a high-entropy alloy-high graphene content diffusion barrier layer. (7) A Cu electroplating layer is formed on the surface of the high-entropy alloy-high graphene content diffusion barrier layer to obtain a copper interconnect structure.

2. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, The content of low-graphene ranges from 1.0 to 2.4 vol%, the content of medium-graphene ranges from 2.5 to 4.0 vol%, and the content of high-graphene ranges from 4.1 to 5.0 vol%.

3. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, The sputtering power of high-entropy alloy targets is between 130-220W, while that of graphene targets is between 40-70W.

4. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, The sputtering bias voltage is between -150V and -100V.

5. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, The thickness of sputtered deposited layers of high-entropy alloys with low graphene content is between 80-100 nm, the thickness of sputtered deposited layers of high-entropy alloys with medium graphene content is less than 120-140 nm, and the thickness of sputtered deposited layers of high-entropy alloys with high graphene content is between 140-160 nm.

6. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, In step (7), the substrate is pretreated before electroplating by using Ar plasma at a power of 80-100w, a pressure of 0.8-1.0Pa, and a time of 8-10min.

7. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, In step (7), the electroplating temperature shall not be lower than 25°C.

8. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, In step (7), the thickness of the electroplated Cu is not less than 10 μm.

9. The method for preparing a gradient composite high-entropy alloy-graphene diffusion barrier layer according to claim 1, characterized in that, The high-entropy alloy includes at least four of the following: titanium, vanadium, chromium, zirconium, tantalum, molybdenum, niobium, aluminum, and nickel.

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