A molybdenum metal pattern manufacturing method and a semiconductor structure

Abstract

The application discloses a molybdenum metal pattern manufacturing method and a semiconductor structure. The method comprises the following steps: providing a substrate; forming a molybdenum metal layer on the surface of the substrate; using a plasma containing oxygen gas, chlorine gas and bromine gas to perform patterned etching on the molybdenum metal layer to form a molybdenum metal pattern on the surface of the substrate; using an oxidizing solution to perform first processing on the sidewall of the molybdenum metal pattern at a first temperature to generate a molybdenum trioxide layer on the surface of the sidewall; using a neutral dissolving solution to perform second processing on the surface of the sidewall at a second temperature to dissolve and remove the molybdenum trioxide layer; the first temperature and the second temperature are greater than 0 DEG C and less than 85 DEG C; the first processing and the second processing are alternately and repeatedly performed for multiple times to reduce the surface roughness of the sidewall. The application can obtain a vertical sidewall morphology and improve the surface roughness of the sidewall.

Description

Technical Field

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

[0002] At advanced nodes, when forming metal interconnect layers on substrates, the industry is exploring subtractive patterning processes (depositing metal first, then etching the pattern) to create the most critical and densely patterned bottom metal layers (such as M1 and M2). Molybdenum (Mo) has the advantages of good adhesion to dielectric materials and the absence of a diffusion barrier layer, making it a promising candidate material for the subtractive method's bottom metal layers. However, when molybdenum is etched in a conventional oxygen and chlorine-containing gas system, byproducts (MoO) are generated. x Cl y The high sensitivity to lateral bombardment by free radicals results in insufficient protection of the etched structure's sidewalls by byproducts, leading to isotropic etching and a tendency to produce severe sidewall depressions that prevent the acquisition of vertical profiles. Furthermore, existing dry etching processes also produce poor sidewall roughness. These problems affect the fabrication of high aspect ratio molybdenum metal patterns, making it difficult to reduce resistivity. 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 method for fabricating molybdenum metal patterns and a semiconductor structure.

[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 creating molybdenum metal patterns, including: Provide substrate; A molybdenum metal layer is formed on the surface of the substrate; The molybdenum metal layer is patterned by using plasma containing oxygen, chlorine, and bromine gases to form a molybdenum metal pattern on the surface of the substrate. At a first temperature, the sidewalls of the molybdenum metal pattern are subjected to a first treatment using an oxidizing solution to generate a molybdenum trioxide layer on the surface of the sidewalls. At a second temperature, a neutral solvent is used to perform a second treatment on the surface of the sidewall to dissolve and remove the molybdenum trioxide layer; The first temperature and the second temperature are greater than 0°C and less than 85°C; The first and second processes are performed alternately and repeatedly to reduce the surface roughness of the sidewall.

[0005] In some embodiments, during the etching process, bromine radicals and oxygen radicals contained in the plasma are used to adsorb and react on the sidewall surface of the forming molybdenum metal pattern to form a MoBrO passivation layer to protect the sidewall.

[0006] In some embodiments, the first process and the second process are alternately executed 5 to 20 times.

[0007] In some embodiments, the oxygen-containing gas includes oxygen.

[0008] In some embodiments, the chlorine-containing gas includes chlorine gas.

[0009] In some embodiments, the bromine-containing gas includes hydrogen bromide.

[0010] In some embodiments, during the etching process, the total flow rate of the oxygen-containing gas, chlorine-containing gas, and bromine-containing gas is 50 sccm to 500 sccm, wherein the flow rate of the oxygen-containing gas accounts for 10% to 30%, the flow rate of the chlorine-containing gas accounts for 40% to 60%, the flow rate of the bromine-containing gas accounts for 10% to 30%, the temperature is 10°C to 60°C, the pressure is 5 mTorr to 10 mTorr, the source power is 500 W to 800 W, and the bias power is 20 W to 200 W.

[0011] In some embodiments, the oxidizing solution includes hydrogen peroxide with an alkaline pH.

[0012] In some embodiments, the neutral solution comprises deionized water.

[0013] In some embodiments, the pH value of the hydrogen peroxide is 8 to 11.

[0014] In some embodiments, the concentration of the hydrogen peroxide is 5 wt% to 15 wt%.

[0015] In some embodiments, the first temperature is 30°C to 50°C.

[0016] In some embodiments, the second temperature is 20°C to 80°C.

[0017] In some embodiments, the time for each execution of the first process is 10s to 150s.

[0018] In some embodiments, the time for each execution of the second process is 15s to 60s.

[0019] According to a second aspect of this application, embodiments of this application also provide a semiconductor structure obtained using a molybdenum metal patterning method as provided in any of the embodiments of the first aspect above.

[0020] The embodiments of this application may have, or at least have, the following advantages: (1) By adding bromine-containing gas to the oxygen-containing and chlorine-containing gases used for patterning etching of molybdenum metal layers, bromine free radicals and oxygen free radicals contained in the plasma can be used to adsorb and react on the sidewall surface of the forming molybdenum metal pattern, forming a MoBrO passivation layer for sidewall protection. This passivation layer is sensitive to vertical ion bombardment (removed by sputtering) but insensitive to lateral free radical attacks (retained), achieving "in-situ sidewall protection." This effectively solves the problem of byproducts (MoO₂) generated during conventional etching of molybdenum in oxygen- and chlorine-containing gas systems. x Cl y The insufficient protection of the sidewalls makes the etching isotropic and prone to severe sidewall depressions, thus enabling the acquisition of a more vertical sidewall morphology.

[0021] (2) By further processing the sidewall of the molybdenum metal pattern, the surface of the protrusions on the rough sidewall can be preferentially oxidized by using an oxidizing solution. The processing temperature (first temperature) and the pH value and concentration of the oxidizing solution are controlled to selectively generate a soluble molybdenum trioxide layer on the surface of the sidewall. The molybdenum trioxide layer formed on the sidewall can be easily dissolved and removed by using a neutral dissolving solution at a second temperature (second processing). Thus, the surface roughness of the sidewall can be effectively reduced through the alternating cycle of oxidation and dissolution.

[0022] The process steps in this application are highly compatible. By defining the pattern outline using a dry method and refining the sidewall surface using a wet method, molybdenum metal patterns with higher aspect ratios and higher interconnect density can be obtained, which helps to achieve lower resistance and interconnect stability, and well meets the technical requirements of advanced nodes.

[0023] Other advantages of this application will be described in the following detailed description. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for creating a molybdenum metal pattern according to a preferred embodiment of this application.

[0025] Figure 2 This is a schematic diagram of a preferred embodiment of the present application after forming a molybdenum metal layer and a mask on the surface of a substrate.

[0026] Figure 3 This is a schematic diagram of a molybdenum metal layer after patterning etching to form a molybdenum metal pattern, provided as a preferred embodiment of this application.

[0027] Figure 4This is a schematic diagram of a molybdenum trioxide layer formed on the sidewall surface of a molybdenum metal pattern, according to a preferred embodiment of this application.

[0028] Figure 5 This is a schematic diagram of a preferred embodiment of the present application after dissolving and removing the molybdenum trioxide layer on the sidewall of a molybdenum metal pattern.

[0029] In the figure: 10. Substrate; 11. Molybdenum metal layer; 111. Molybdenum metal pattern; 12. Mask; 13. Molybdenum trioxide layer. Detailed Implementation

[0030] This relates to the byproduct (MoO) generated during the etching of molybdenum (Mo) in a conventional gas system containing oxygen and chlorine. x Cl y The insufficient protection of the etched structure sidewalls makes the etching isotropic, easily leading to severe sidewall depressions that prevent the acquisition of a vertical profile. Furthermore, existing dry etching processes result in poor sidewall roughness. This application provides a method for fabricating molybdenum metal patterns, including: Provide substrate; A molybdenum metal layer is formed on the surface of the substrate; The molybdenum metal layer is patterned by using plasma containing oxygen, chlorine, and bromine gases to form a molybdenum metal pattern on the surface of the substrate. At a first temperature, the sidewalls of the molybdenum metal pattern are subjected to a first treatment using an oxidizing solution to generate a molybdenum trioxide layer on the surface of the sidewalls. At a second temperature, a neutral solvent is used to perform a second treatment on the surface of the sidewall to dissolve and remove the molybdenum trioxide layer; The first temperature and the second temperature are greater than 0°C and less than 85°C; The first and second processes are performed alternately and repeatedly to reduce the surface roughness of the sidewall.

[0031] This application embodiment uses plasma containing oxygen, chlorine, and bromine gases to pattern the molybdenum metal layer. This allows for the formation of a MoBrO passivation layer on the sidewall surface of the forming molybdenum metal pattern, resisting lateral free radical attacks, thus achieving "in-situ sidewall protection" and resulting in a more vertical sidewall morphology. Furthermore, a first treatment of the etched molybdenum metal pattern sidewalls using an oxidizing solution preferentially oxidizes the surfaces of protrusions on the rough sidewalls, selectively forming a soluble molybdenum trioxide layer on the sidewall surface. This layer can be easily dissolved and removed using a neutral solvent in a second treatment, effectively reducing the surface roughness of the sidewalls. This facilitates obtaining molybdenum metal patterns with higher aspect ratios and higher interconnect density, achieving lower resistance and better interconnect stability.

[0032] This application also provides a semiconductor structure obtained using the above-described molybdenum metal patterning method.

[0033] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0034] refer to Figure 1 In a first aspect, embodiments of this application provide a method for creating molybdenum metal patterns, which may include the following steps in sequence: Step S11: Provide a substrate.

[0035] refer to Figure 2 In some embodiments, a substrate 10 is used for further forming molybdenum metal patterns (molybdenum metal lines) on the substrate 10 to form the semiconductor structure provided in the embodiments of this application. The substrate 10 may include any suitable type of semiconductor substrate and material. For example, the substrate 10 may include a silicon (Si) substrate, a germanium (Ge) substrate, or a germanium-silicon (SiGe) substrate, or a III / V compound semiconductor substrate, such as a gallium arsenide (GaAs) substrate, an indium gallium arsenide (InGaAs) substrate, or similar materials, etc.

[0036] In some embodiments, substrate 10 may include a wafer.

[0037] Step S12: Form a molybdenum metal layer on the surface of the substrate.

[0038] refer to Figure 2 In some embodiments, a deposition process may be used to form a molybdenum metal layer 11 (a metal layer of molybdenum material) on the surface of the substrate 10.

[0039] Step S13: Pattern the molybdenum metal layer to form a molybdenum metal pattern on the surface of the substrate.

[0040] refer to Figure 2In some embodiments, a plurality of masks 12 are formed on the surface of the molybdenum metal layer 11, and any two adjacent masks 12 have an opening that serves as an etching window.

[0041] In some embodiments, mask 12 may include a hard mask. The material of the hard mask may include TiN, etc.

[0042] In some embodiments, the mask 12 is a TiN hard mask, and silicon dioxide hard masks or silicon nitride hard masks are avoided on the surface of the molybdenum metal layer 11. If a silicon dioxide hard mask or a silicon nitride hard mask is used for patterning etching of the molybdenum metal layer, byproducts (Mo-Si phase and Mo-Si-O-Cl complex) are extremely difficult to remove, due to the redeposition of the silicon dioxide hard mask or silicon nitride hard mask material during the etching process. Therefore, by using a TiN hard mask (without using a silicon dioxide hard mask or a silicon nitride hard mask) as the mask 12 for patterning etching of the molybdenum metal layer 11, the problem of byproduct residue caused by the reaction between the sputtered Si-containing mask material and Mo can be solved, and the generation of the above-mentioned residues can be avoided while achieving anisotropic etching.

[0043] In some embodiments, the method of forming a TiN hard mask may include: A TiN layer and a photoresist layer are sequentially formed on the surface of the molybdenum metal layer 11; Photolithography is used to lithographically form multiple photoresist patterns on the surface of the TiN layer. By patterning the exposed TiN layer with photoresist, multiple TiN hard masks serving as masks 12 are formed on the surface of the molybdenum metal layer 11. Then, the photoresist pattern is removed. Thus, the exposed molybdenum metal layer 11 can be patterned and etched through the TiN hard masks to form a molybdenum metal pattern on the surface of the substrate 10.

[0044] In some embodiments, a plasma of a mixture of a first chlorine-containing gas, a second chlorine-containing gas, a first nitrogen-containing gas, a hydrocarbon-containing gas, and a diluent gas (a first etching gas) can be used. Anisotropic dry plasma etching is performed on the surface of the exposed TiN layer through the openings between the photoresist patterns. The etching can be stopped on the surface of the molybdenum metal layer 11 by detecting the etching endpoint, thereby forming a TiN hard mask formed by the patterned TiN layer on the surface of the molybdenum metal layer 11.

[0045] In some embodiments, the first chlorine-containing gas may include chlorine gas, etc.

[0046] In some embodiments, the second chlorine-containing gas may include boron trichloride (BCl3), etc.

[0047] In some embodiments, the first nitrogen-containing gas may include nitrogen or the like.

[0048] In some embodiments, the hydrocarbon-containing gas may include methane (CH4) or the like. By adding a hydrocarbon-containing gas to the first etching gas, the sidewalls of the photoresist pattern and the TiN hard mask during etching can be passivated for protection, improving pattern transfer accuracy and the sidewall quality of the TiN hard mask, maintaining the vertical sidewall morphology, which helps to improve the dimensional uniformity of the molybdenum metal pattern formed by subsequent etching, and reducing sidewall roughness.

[0049] In some embodiments, the diluent gas may include argon or the like.

[0050] In some embodiments, when etching the TiN layer, the flow rate percentage of the first chlorine-containing gas (chlorine) in the first etching gas (first chlorine-containing gas, second chlorine-containing gas, first nitrogen-containing gas, hydrocarbon-containing gas, and dilution gas) is 20%–50%, the flow rate percentage of the second chlorine-containing gas (boron trichloride) is 0%–10%, the flow rate percentage of the first nitrogen-containing gas (nitrogen) is 9%–11%, the flow rate percentage of the hydrocarbon-containing gas (methane) is 10%–20%, and the flow rate percentage of the dilution gas (argon) is 30%–40%. For example, the flow rate percentage of the first chlorine-containing gas (chlorine) can be 20%, 21%, 22%, 25%, 28%, 30%, 33%, 36%, 39%, 40%, 42%, 44%, 45%, 47%, 49%, or 50%, or any value between any two of the aforementioned flow rate percentages. The flow rate percentage of the second chlorine-containing gas (boron trichloride) can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, or any value between any two of the aforementioned flow rate percentages. The flow rate percentage of the first nitrogen-containing gas (nitrogen) can be 9%, 10%, or 11%, or any value between any two of the aforementioned flow rate percentages. The flow rate percentage of the hydrocarbon-containing gas (methane) can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, or any value between any two of the aforementioned flow rate percentages. The flow rate percentage of the dilution gas (argon) can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, or any value between any two of the aforementioned flow rate percentages.

[0051] In some embodiments, when etching the TiN layer, the total flow rate of the first etching gas is 50 sccm to 500 sccm. For example, the total flow rate of the first etching gas can be 50 sccm, 60 sccm, 90 sccm, 100 sccm, 115 sccm, 155 sccm, 185 sccm, 200 sccm, 215 sccm, 250 sccm, 275 sccm, 290 sccm, 300 sccm, 310 sccm, 345 sccm, 375 sccm, 380 sccm, 400 sccm, 425 sccm, 450 sccm, 488 sccm, or 500 sccm, or any value between any two of the aforementioned flow rate values.

[0052] In some embodiments, the temperature for etching the TiN layer is 10°C to 60°C. For example, the temperature can be 10°C, 15°C, 18°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C, or any value between any two of the aforementioned temperature values.

[0053] In some embodiments, the pressure during etching of the TiN layer is 5 mTorr to 15 mTorr. For example, the pressure can be 5 mTorr, 6 mTorr, 7 mTorr, 8 mTorr, 9 mTorr, 10 mTorr, 11 mTorr, 12 mTorr, 13 mTorr, 14 mTorr, or 15 mTorr, or any value between any two of the aforementioned pressure values.

[0054] In some embodiments, when etching the TiN layer, the source power is 400W to 600W (frequency 13.56MHz). For example, the source power can be 400W, 410W, 430W, 450W, 480W, 500W, 520W, 550W, 590W, or 600W, or any value between any two of the aforementioned power values.

[0055] In some embodiments, when etching the TiN layer, the bias power is 20W to 100W (frequency 13.56MHz). For example, the bias power can be 20W, 30W, 40W, 50W, 60W, 70W, 80W, 90W or 100W, or any value between any two of the aforementioned power values.

[0056] Thus, by coordinating the control of the above-mentioned flow ratio, flow rate, temperature, pressure, source power, bias power, etc., TiN hard masks with high pattern accuracy and vertical sidewall morphology can be obtained.

[0057] In some embodiments, a plasma of a mixture of a first oxygen-containing gas and a carbon-containing gas (second etching gas), and a plasma of a mixture of a second nitrogen-containing gas and a nitrogen-hydrogen-containing gas (third etching gas) can be used for dry photoresist stripping to remove the photoresist pattern and clean the surface of the TiN hard mask.

[0058] In some embodiments, the first oxygen-containing gas may include oxygen or the like.

[0059] In some embodiments, the carbon-containing oxygen gas may include carbon monoxide, etc.

[0060] In some embodiments, the second nitrogen-containing gas may include nitrogen or the like.

[0061] In some embodiments, the nitrogen-containing hydrogen gas may include ammonia (NH3) or the like.

[0062] In some embodiments, the dry photoresist stripping process can be divided into two steps. The first step uses a plasma of a mixture of oxygen-containing gas (oxygen) and carbon-containing oxygen gas (carbon monoxide) to remove most of the photoresist pattern (the timing of the first step can be controlled by detecting the CO signal). The second step uses a plasma of a mixture of nitrogen-containing gas (nitrogen) and nitrogen-hydrogen gas (ammonia) (which does not contain oxygen-containing gas) to thoroughly remove the remaining photoresist pattern while cleaning the surface of the TiN hard mask. This can improve the surface condition of TiN and remove any O free radicals or O dangling bonds that may exist on the TiN surface.

[0063] In some embodiments, when removing the photoresist pattern, the flow rate percentage of the first oxygen-containing gas (oxygen) in the second etching gas is 70% to 90%, and the flow rate percentage of the nitrogen-hydrogen gas (ammonia) in the third etching gas is 70% to 90%. For example, the flow rate percentage of the first oxygen-containing gas (oxygen) in the second etching gas can be 70%, 71%, 75%, 77%, 79%, 80%, 83%, 86%, 88%, 89%, or 90%, or any value between any two of the aforementioned flow rate percentages. The flow rate percentage of the nitrogen-hydrogen gas (ammonia) in the third etching gas can be 70%, 71%, 73%, 75%, 78%, 79%, 80%, 81%, 84%, 87%, 89%, or 90%, or any value between any two of the aforementioned flow rate percentages.

[0064] In some embodiments, the temperature for removing the photoresist pattern is 100°C to 300°C. For example, the temperature may be 100°C, 105°C, 120°C, 125°C, 130°C, 150°C, 180°C, 200°C, 220°C, 250°C, 255°C, 285°C, or 300°C, or any value between any two of the aforementioned temperature values.

[0065] In some embodiments, the pressure is 100 mTorr to 2000 mTorr when removing the photoresist pattern. For example, the pressure can be 100 mTorr, 200 mTorr, 500 mTorr, 800 mTorr, 1000 mTorr, 1100 mTorr, 1300 mTorr, 1500 mTorr, 1700 mTorr, 1900 mTorr, or 2000 mTorr, or any value between any two of the aforementioned pressure values.

[0066] In some embodiments, when removing the photoresist pattern, the source power during the first step is 500W to 4000W (frequency of 60MHz). For example, the source power during the first step can be 500W, 600W, 800W, 1000W, 1500W, 2000W, 2500W, 3000W, 3500W, or 4000W, or any value between any two of the aforementioned power values. The source power during the second step is 500W to 4000W (frequency of 13.56MHz). For example, the source power during the second step can be 500W, 550W, 750W, 990W, 1000W, 1100W, 1500W, 2000W, 2500W, 3000W, 3500W, or 4000W, or any value between any two of the aforementioned power values.

[0067] In some embodiments, bias power is turned off when removing the photoresist pattern.

[0068] By coordinating the control of the above-mentioned flow rate ratio, temperature, pressure, source power, etc., the surface of the TiN hard mask can be cleaned while completely removing the photoresist pattern, ensuring the critical dimensions of the TiN hard mask and the molybdenum metal pattern formed by subsequent etching, and preventing the distortion of the line pattern.

[0069] refer to Figure 3 In some embodiments, a plasma containing oxygen gas (second oxygen gas), chlorine gas (third chlorine gas), and a mixture of bromine gas (fourth etching gas) can be used to perform anisotropic dry plasma etching on the surface of the exposed molybdenum metal layer 11 through the openings between the masks 12. By patterning the molybdenum metal layer 11, a molybdenum metal pattern 111 (molybdenum metal line) formed by the patterned molybdenum metal layer 11 is formed on the surface of the substrate 10.

[0070] Molybdenum metal undergoes severe isotropic etching in a plasma of pure chlorine and oxygen, thus failing to achieve a vertical profile. In this embodiment, this problem is effectively solved by adding a bromine-containing gas to the oxygen-containing and chlorine-containing gases. During etching of the molybdenum metal layer 11, bromine and oxygen free radicals present in the plasma are adsorbed and reacted on the sidewall surface of the forming molybdenum metal pattern 111, forming a low-volatility MoBrO passivation layer to protect the sidewalls of the forming molybdenum metal pattern 111. This MoBrO passivation layer is sensitive to ion bombardment from the vertical direction (and is sputtered away), but insensitive to free radical attacks from the side (and is retained), thereby achieving "in-situ sidewall protection" of the forming molybdenum metal pattern 111, thus obtaining a more vertical sidewall morphology of the molybdenum metal pattern 111.

[0071] In some embodiments, the oxygen-containing gas (the second oxygen-containing gas) may include oxygen or the like.

[0072] In some embodiments, the chlorine-containing gas (the third chlorine-containing gas) may include chlorine gas, etc.

[0073] In some embodiments, the bromine-containing gas may include hydrogen bromide (HBr) or the like.

[0074] In some embodiments, when etching the molybdenum metal layer 11, the flow rate of the oxygen-containing gas (oxygen) in the fourth etching gas (oxygen-containing gas, chlorine-containing gas, and bromine-containing gas) is 10% to 30%, the flow rate of the chlorine-containing gas (chlorine) is 40% to 60%, and the flow rate of the bromine-containing gas (hydrogen bromide) is 10% to 30%. For example, the flow rate percentage of the oxygen-containing gas can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, or any value between any two of the aforementioned flow rate percentages. The flow rate percentage of chlorine-containing gas can be 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or 60%, or any value between any two of the aforementioned flow rate percentages. The flow rate percentage of bromine-containing gas can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, or any value between any two of the aforementioned flow rate percentages.

[0075] In some embodiments, when etching the molybdenum metal layer 11, the total flow rate of the fourth etching gas (containing oxygen, chlorine, and bromine gases) is 50 sccm to 500 sccm. For example, the total flow rate of the fourth etching gas can be 50 sccm, 60 sccm, 80 sccm, 100 sccm, 110 sccm, 150 sccm, 180 sccm, 200 sccm, 220 sccm, 250 sccm, 270 sccm, 290 sccm, 300 sccm, 310 sccm, 340 sccm, 360 sccm, 380 sccm, 400 sccm, 430 sccm, 450 sccm, 480 sccm, or 500 sccm, or any value between any two of the aforementioned flow rate values.

[0076] In some embodiments, the temperature for etching the molybdenum metal layer 11 is 10°C to 60°C. For example, the temperature may be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C, or any value between any two of the aforementioned temperature values.

[0077] In some embodiments, the pressure for etching the molybdenum metal layer 11 is 5 mTorr to 10 mTorr. For example, the pressure can be 5 mTorr, 5.5 mTorr, 6 mTorr, 6.5 mTorr, 7 mTorr, 7.5 mTorr, 8 mTorr, 8.5 mTorr, 9 mTorr, 9.5 mTorr, or 10 mTorr, or any value between any two of the aforementioned pressure values.

[0078] In some embodiments, when etching the molybdenum metal layer 11, the source power is 500W to 800W. For example, the source power can be 500W, 510W, 530W, 550W, 580W, 600W, 620W, 650W, 690W, 700W, 730W, 760W, 780W, or 800W, or any value between any two of the aforementioned power values.

[0079] In some embodiments, when etching the molybdenum metal layer 11, the bias power is 20W to 200W. For example, the bias power can be 20W, 30W, 50W, 70W, 90W, 100W, 115W, 130W, 150W, 180W or 200W, or any value between any two of the aforementioned power values.

[0080] In some embodiments, when etching the molybdenum metal layer 11, the bias power can be set to alternately turn on and off (pulse bias mode) to form periodic pulse etching, with a duty cycle of 10% to 30%. During the period when the bias power (bias voltage) is off, ion bombardment is stopped, which allows the MoBrO passivation layer to be better retained on the sidewall, achieving continuous and effective protection of the sidewall.

[0081] By coordinating the control of the aforementioned flow rate ratio, flow rate, temperature, pressure, source power, and bias power, anisotropic etching is achieved on the surface of the molybdenum metal layer 11 in the opening. This forms a well-formed, uniformly sized trench with vertical sidewalls that penetrates the molybdenum metal layer 11 at the bottom of the opening, exposing the surface of the substrate 10 below. Furthermore, by defining the pattern contour using a dry method, multiple well-formed, uniformly sized molybdenum metal patterns 111 (molybdenum metal lines) with vertical sidewalls are formed on the surface of the substrate 10, segmented by the trenches.

[0082] Step S14: Surface oxidation is performed on the sidewalls of the molybdenum metal pattern to generate a molybdenum trioxide layer on the surface of the sidewalls.

[0083] Using the dry etching process described in the embodiments of this application to etch the molybdenum metal layer 11 can yield a molybdenum metal pattern 111 with uniform size and vertical sidewalls and a good morphology. However, the sidewall roughness may still be poor. Therefore, the sidewalls of the molybdenum metal pattern 111 can be further surface-treated by the surface treatment process described in the embodiments of this application to improve the sidewall roughness of the molybdenum metal pattern 111.

[0084] In some embodiments, the sidewall surface of the molybdenum metal pattern 111 undergoes a first treatment. Prior to this, the mask 12 on top of the molybdenum metal pattern 111 may be removed, such as... Figure 4 As shown.

[0085] In some embodiments, when the mask 12 on top of the molybdenum metal pattern 111 is a TiN hard mask, an aqueous solution comprising a fluorinated etchant, an oxidant, an organic solvent, and a corrosion inhibitor can be used as a wet etching solution to perform wet etching treatment on the TiN hard mask, so as to selectively remove the TiN hard mask (the corrosion rate of this wet etching solution on molybdenum is much lower than the corrosion rate on TiN). The fluorine ions contained in the fluorinated etchant attack the TiN lattice, the oxidant maintains the reactivity, and the corrosion inhibitor selectively protects Mo, thereby achieving the purpose of highly selective removal of TiN.

[0086] In some embodiments, the fluorine-containing etchant may include NH4F, etc.

[0087] In some embodiments, the oxidant may include hydrogen peroxide (H2O2) or the like.

[0088] In some embodiments, the organic solvent may include DMSO (dimethyl sulfoxide (C2H6OS)) or the like.

[0089] In some embodiments, corrosion inhibitors may include 2-aminopyridine (C5H6N2), etc.

[0090] In some embodiments, the wet etching solution contains 0.5% to 3% (wt%) of fluorinated etchant (NH4F), 1% to 4% of oxidant (hydrogen peroxide (concentration 30%)), 20% to 50% of organic solvent (DMSO), 0.3% to 3% of corrosion inhibitor (2-aminopyridine), and the remainder is deionized water.

[0091] In some embodiments, when selectively removing the TiN hard mask using a wet etching solution, the temperature is between 20°C and 60°C. For example, the temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C, or any value between any two of the aforementioned temperature values.

[0092] refer to Figure 4 In some embodiments, after removing the mask 12, an oxidizing solution can be used to perform a first treatment on the sidewalls of the molybdenum metal pattern 111 at a first temperature to oxidize the surface of the molybdenum material on the sidewalls of the molybdenum metal pattern 111, with the aim of selectively generating a soluble molybdenum trioxide layer 13 on the surface of the sidewalls of the molybdenum metal pattern 111 (after removing the mask 12, a molybdenum trioxide layer 13 will also be generated on the top surface of the molybdenum metal pattern 111 at the same time).

[0093] In some embodiments, the oxidizing solution may include hydrogen peroxide.

[0094] In some embodiments, hydrogen peroxide is alkaline. That is, the pH value of hydrogen peroxide is alkaline. Under alkaline conditions, H2O2 (hydrogen peroxide) dissociates to generate HO2⁻ ions, whose standard electrode potential is significantly higher than that of H2O2 molecules under acidic conditions (under acidic conditions (e.g., pH=1-5), H2O2 mainly exists in molecular form, its oxidation potential is low, and a dense passivation layer easily forms on the surface of molybdenum metal, hindering the continuous progress of the oxidation reaction). The oxidation capacity is greatly enhanced, which can effectively overcome the passivation tendency of the molybdenum surface and achieve efficient and high-valence oxidation of molybdenum (molybdenum trioxide).

[0095] In some embodiments, the pH value of hydrogen peroxide is 8 to 11. For example, the pH value of hydrogen peroxide can be 8, 9, 10, or 11, etc., but it is not limited to these.

[0096] In some embodiments, the pH value of hydrogen peroxide can be adjusted by adding a small amount of NH4OH or NaOH to achieve a pH value of 8 to 11, which can promote the formation and dissolution of molybdenum trioxide and improve the uniformity of the process for reducing the roughness of the sidewalls of molybdenum metal patterns.

[0097] In some embodiments, the concentration of hydrogen peroxide is 5 wt% to 15 wt% (weight percentage of hydrogen peroxide in hydrogen peroxide). For example, the concentration of hydrogen peroxide may be 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, or 15 wt%, or any value between any two of the aforementioned percentage values.

[0098] In some embodiments, the first temperature is 30°C to 50°C. For example, the first temperature may be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, or 50°C, or any value between any two of the aforementioned temperature values.

[0099] Within the range of pH, concentration, and first temperature of the hydrogen peroxide mentioned above, molybdenum can be selectively oxidized to form soluble molybdenum trioxide (MoO3), and molybdenum can be effectively prevented from being oxidized to form insoluble substances such as molybdenum dioxide (MoO2).

[0100] Step S15: Dissolve and remove the molybdenum trioxide layer generated on the sidewall surface.

[0101] refer to Figure 5 In some embodiments, a neutral solvent can be used, and the sidewall surface of the molybdenum metal pattern 111 can be subjected to a second treatment at a second temperature to dissolve and remove the molybdenum trioxide layer 13 formed by the previous oxidation step on the sidewall of the molybdenum metal pattern 111 (the molybdenum trioxide layer 13 on the top surface of the molybdenum metal pattern 111 will also be dissolved and removed). Thus, after removing the molybdenum trioxide layer 13, a semiconductor structure with the surface-treated molybdenum metal pattern 111 on the substrate 10 is obtained.

[0102] In some embodiments, the neutral dissolving solution may include deionized water. Dissolving the molybdenum trioxide layer 13 with deionized water can dissolve the molybdenum trioxide into molybdate ions (MoO4). 2⁻ This allows the molybdenum trioxide layer 13 to be completely dissolved and removed.

[0103] The MoBrO passivation layer remaining on the sidewall of molybdenum metal pattern 111 will also be dissolved (dissolved into MoO4) during the first and second treatments. 2⁻ and Br -The removal of the MoBrO passivation layer not only inherits the water solubility of MoO3, but the presence of Br also increases the hydrophilicity and reactivity of the MoBrO compound material, making its dissolution rate even better than that of pure MoO3.

[0104] In some embodiments, the second temperature may be 20°C to 80°C. For example, the second temperature may be 20°C, 25°C, 30°C, 35°C, 40°C, 45°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.

[0105] By first treating the sidewalls of the molybdenum metal pattern 111 with an oxidizing solution, the surface of the protrusions on the rough sidewalls caused by dry etching of the molybdenum metal pattern 111 can be preferentially oxidized to generate a soluble molybdenum trioxide layer 13, making the oxidation more complete and the interface after oxidation more flat. Then, a neutral dissolving solution is used to continue the second treatment of the sidewalls of the molybdenum metal pattern 111 to dissolve and remove the molybdenum trioxide layer 13 formed on the sidewalls of the molybdenum metal pattern 111, thereby removing at least part of the protrusions.

[0106] Step S16: Repeat steps S14 to S15 multiple times to reduce the surface roughness of the sidewall.

[0107] In some embodiments, steps S14 to S15 can be repeated multiple times, i.e., the first and second processes can be alternately and cyclically executed multiple times to finely control the degree of oxidation and the degree of removal of the protrusions each time. This allows for effective reduction of the surface roughness of the molybdenum metal pattern 111 sidewalls through wet finishing of the sidewall surface. This makes the sidewalls of the molybdenum metal pattern 111 gradually smoother, improves linewidth uniformity, reduces the risk of short circuits or open circuits, ensures good connection with the upper metal via, and helps to improve the aspect ratio of the molybdenum metal pattern 111 to reduce resistance.

[0108] In some embodiments, the first process and the second process may be alternately executed 5 to 20 times. For example, the first process and the second process may be alternately executed 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 times, and are not limited thereto.

[0109] In some embodiments, when the first process and the second process are executed alternately and cyclically, the time for each execution of the first process is 10s to 150s. For example, the time for each execution of the first process can be 10s, 11s, 15s, 20s, 30s, 50s, 70s, 90s, 100s, 105s, 120s, 135s, 145s, or 150s, or any value between any two of the aforementioned time values.

[0110] In some embodiments, when the first and second processes are alternately executed, the duration of each second process is 15 to 60 seconds, limited to the complete dissolution of the molybdenum trioxide generated each time. For example, the duration of each second process may be 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, or 60 seconds, or any value between any two of the aforementioned time values.

[0111] Therefore, by using plasmas containing oxygen, chlorine, and bromine gases to pattern the molybdenum metal layer 11, a molybdenum metal pattern 111 with a vertical sidewall profile can be formed on the surface of the substrate. Further surface treatment of the sidewalls of the molybdenum metal pattern 111, based on an alternating oxidation-dissolution cycle, can effectively reduce the surface roughness of the sidewalls. Thus, by defining the profile of the molybdenum metal pattern 111 through plasma dry etching and refining the sidewall surface through oxidation-dissolution treatment, a molybdenum metal pattern 111 with a higher aspect ratio and higher interconnect density can be obtained, achieving lower resistance and interconnect stability.

[0112] In a second aspect, embodiments of this application also provide a semiconductor structure obtained using a molybdenum metal patterning method as provided in any of the embodiments of the first aspect above.

[0113] refer to Figure 5 In some embodiments, the semiconductor structure includes a substrate 10 and a molybdenum metal pattern 111 (molybdenum metal line) disposed on the surface of the substrate 10. The molybdenum metal pattern 111 is obtained by using a molybdenum metal patterning method provided in any of the embodiments of the first aspect described above. The molybdenum metal pattern 111 can be used to form the bottom metal layer (such as M1, M2) with the densest patterning in the metal interconnect layer.

[0114] The molybdenum metal pattern 111 is obtained by patterning and etching the molybdenum metal layer 11 using a plasma of a mixed gas containing oxygen (oxygen), chlorine (chlorine), and bromine (hydrogen bromide). The surface roughness is reduced by further performing oxidation and dissolution-based surface treatments (first treatment and second treatment and their cycles) on the sidewalls of the molybdenum metal pattern 111 after etching.

[0115] In a third aspect, embodiments of this application also provide a plasma processing apparatus for performing the molybdenum metal patterning 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) processing equipment or capacitively coupled plasma (CCP) processing equipment, etc.

[0116] In other aspects, embodiments of this application also provide an electronic device, including a semiconductor structure obtained using the molybdenum metal patterning method described above. The electronic device can be a storage device, mobile phone, computer, tablet computer, electronic instrument, television, artificial intelligence device, etc.

[0117] In summary, this embodiment utilizes plasmas containing oxygen, chlorine, and bromine gases to pattern the molybdenum metal layer 11. This allows for the formation of a MoBrO passivation layer on the sidewall surface of the forming molybdenum metal pattern 111, resisting lateral free radical attacks, thus achieving "in-situ sidewall protection" and resulting in a more vertical sidewall morphology. Furthermore, by performing oxidation- and dissolution-based surface treatments on the sidewalls of the etched molybdenum metal pattern 111, the surface roughness of the sidewalls is effectively reduced. This facilitates obtaining molybdenum metal patterns 111 with higher aspect ratios and higher interconnect density, achieving lower resistance and interconnect stability, and effectively meeting the technical requirements of advanced nodes.

[0118] 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 molybdenum metal patterns, characterized in that, include: Provide substrate; A molybdenum metal layer is formed on the surface of the substrate; The molybdenum metal layer is patterned by using plasma containing oxygen, chlorine, and bromine gases to form a molybdenum metal pattern on the surface of the substrate. At a first temperature, the sidewalls of the molybdenum metal pattern are subjected to a first treatment using an oxidizing solution to generate a molybdenum trioxide layer on the surface of the sidewalls. At a second temperature, a neutral solvent is used to perform a second treatment on the surface of the sidewall to dissolve and remove the molybdenum trioxide layer; The first temperature and the second temperature are greater than 0°C and less than 85°C; The first and second processes are alternately executed multiple times to reduce the surface roughness of the sidewall; The oxidizing solution includes hydrogen peroxide with a pH of 8 to 11 and a concentration of 5 wt% to 15 wt%, to promote the formation and dissolution of molybdenum trioxide and improve the uniformity of the process for reducing the roughness of the sidewalls of molybdenum metal patterns. The step of patterning the molybdenum metal layer to form a molybdenum metal pattern on the surface of the substrate includes: A TiN layer and a photoresist pattern are sequentially formed on the surface of a molybdenum metal layer; A plasma containing a mixture of a first chlorine-containing gas, a second chlorine-containing gas, a first nitrogen-containing gas, a hydrocarbon-containing gas, and a diluent gas is used to etch a TiN layer through a photoresist pattern, forming a TiN hard mask on the surface of the molybdenum metal layer. The sidewalls of the photoresist pattern and the etched TiN hard mask are passivated and protected using a hydrocarbon-containing gas. First, a plasma of a mixture of oxygen-containing gas and carbon-containing gas is used to remove most of the photoresist pattern; then, a plasma of a mixture of nitrogen-containing gas and nitrogen-hydrogen-containing gas is used to thoroughly remove the remaining photoresist pattern while cleaning the surface of the TiN hard mask. By using a TiN hard mask, the exposed molybdenum metal layer on the surface is patterned and etched to form a molybdenum metal pattern on the surface of the substrate.

2. The method for fabricating molybdenum metal patterns according to claim 1, characterized in that, During the patterning etching, bromine free radicals and oxygen free radicals contained in the plasma containing oxygen-containing gas, chlorine-containing gas, and bromine-containing gas are adsorbed and reacted on the sidewall surface of the forming molybdenum metal pattern to form a MoBrO passivation layer to protect the sidewall.

3. The method for fabricating molybdenum metal patterns according to claim 1, characterized in that, The first and second processes are executed alternately 5 to 20 times.

4. The method for fabricating molybdenum metal patterns according to claim 1, characterized in that, The oxygen-containing gas includes oxygen; and / or, the chlorine-containing gas includes chlorine; and / or, the bromine-containing gas includes hydrogen bromide; and / or, the first chlorine-containing gas includes chlorine, the second chlorine-containing gas includes boron trichloride, the first nitrogen-containing gas includes nitrogen, the hydrocarbon-containing gas includes methane, and the diluent gas includes argon; and / or, the first oxygen-containing gas includes oxygen, the hydrocarbon-oxygen gas includes carbon monoxide, the second nitrogen-containing gas includes nitrogen, and the nitrogen-hydrogen-containing gas includes ammonia.

5. The method for fabricating molybdenum metal patterns according to claim 1, characterized in that, During the patterning etching, the total flow rate of oxygen-containing gas, chlorine-containing gas, and bromine-containing gas is 50 sccm to 500 sccm, with the flow rate of oxygen-containing gas accounting for 10% to 30%, the flow rate of chlorine-containing gas accounting for 40% to 60%, and the flow rate of bromine-containing gas accounting for 10% to 30%. The temperature is 10°C to 60°C, the pressure is 5 mTorr to 10 mTorr, the source power is 500 W to 800 W, and the bias power is 20 W to 200 W.

6. The method for fabricating molybdenum metal patterns according to claim 1, characterized in that, The neutral solution includes deionized water.

7. The method for fabricating molybdenum metal patterns according to claim 1, characterized in that, The first temperature is 30℃~50℃; and / or, the second temperature is 20℃~80℃.

8. The method for fabricating molybdenum metal patterns according to claim 1, characterized in that, The execution time of the first process is 10s to 150s each time; and / or the execution time of the second process is 15s to 60s each time.

9. A semiconductor structure, characterized in that, It is obtained using the molybdenum metal pattern making method as described in any one of claims 1-8.

Images