Treatment method for alternate deposition and etching of furnace tube type titanium nitride

Abstract

The invention relates to the field of semiconductor manufacturing processes, in particular to a furnace tube type titanium nitride deposition and etching alternating processing method. The processing method comprises the following steps: providing a semiconductor wafer of which the surface is provided with a patterned deep hole structure; performing first titanium nitride deposition on the surface of the wafer to form a titanium nitride layer with a preset partial thickness; etching gas is adopted to carry out back etching on the titanium nitride layer, wherein the etching gas comprises fluorine-containing gas, nitrogen and oxygen; and second titanium nitride deposition is carried out on the surface of the wafer after back etching, the steps form a deposition-etching alternate cycle, the deposition-etching alternate cycle is repeatedly carried out until a preset cut-off condition is met, and the cycle is terminated to form the titanium nitride film with the target thickness. According to the method, the specific combination of the fluorine-containing gas, the nitrogen and the oxygen is introduced in the back etching step, and the deposition-etching circulation process is optimized, so that the size loading effect is effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing processes, and more specifically, to a furnace tube-type titanium nitride (TiN) deposition and etching alternating process and semiconductor structure. Background Technology

[0002] In the field of advanced semiconductor device manufacturing, titanium nitride (TiN) is frequently used as a barrier layer material in capacitor electrodes, metal gates, and interconnect structures due to its excellent conductivity, chemical stability, and good compatibility with semiconductor materials. Furnace tube systems, as one of the core pieces of equipment in semiconductor mass production, can process multiple wafers simultaneously and offer excellent temperature uniformity and process consistency, making them the preferred equipment for large-scale TiN thin film deposition. They are widely adaptable to the fabrication needs of critical structures such as barrier layers and electrodes in advanced node devices.

[0003] However, when performing TiN atomic layer deposition (ALD) on wafers with high aspect ratio structures using furnace tube equipment, gap effects and size loading effects are commonly encountered. The gap effect refers to the inability of the film to fully fuse at the center line of the structure during the deposition process, forming vertically penetrating micro-voids. The size loading effect refers to the deposition rate depending on the structural size and geometry of the local pattern, leading to uneven film thickness and increased surface roughness, which seriously affects the electrical performance and long-term reliability of the device.

[0004] Figure 1 This is a schematic diagram of the initial morphology of the wafer surface before the process is implemented, such as... Figure 1 The wafer surface shown has a typical high aspect ratio deep via structure. If the existing process of simple deposition without alternating etching is used, the morphology after deposition will be as follows: Figure 2 As shown, obvious gaps 101 are easily formed inside the deep hole structure. These gaps will disrupt the continuity and compactness of the thin film and directly affect the working stability of the chip device.

[0005] To improve the aforementioned filling defects, existing technologies typically employ a cyclic process of alternating atomic layer deposition and etching: first, a TiN film of a certain thickness is deposited, then the structural opening is widened by etching back, and finally deposition continues to complete the filling.

[0006] Among them, the traditional back etching step mostly uses a single N The gas completes the etching process. Figure 3 This demonstrates the morphology of a TiN film deposited to half its thickness in the prior art, at which point N is introduced. The gas is used for back etching, which enlarges the gap to a certain extent; Figure 4 For a single N The morphology after gas etching shows that there is a lot of TiN film remaining in the large opening area, the morphology is uneven, and the size loading effect is significant. Because the etching rate is slower in the larger opening area and faster in the smaller opening area, the surface morphology after etching is uneven, such as more residue and obvious morphological fluctuations in the large opening area. Figure 5 The morphology after subsequent re-deposition, such as Figure 5 As shown, the uneven etching caused by surface undulations in the thin film was not fundamentally improved, ultimately affecting the overall quality of the thin film and the performance of the device.

[0007] Existing deposition-etching processes struggle to deposit uniform, defect-free TiN films in high aspect ratio structures, failing to meet the manufacturing requirements of advanced semiconductor devices. Therefore, there is an urgent need for an alternating titanium nitride deposition-etching method adapted to furnace-type equipment, capable of effectively suppressing size loading effects and improving the filling uniformity and film quality of high aspect ratio structures. Summary of the Invention

[0008] The purpose of this invention is to provide a furnace tube-type titanium nitride deposition and etching alternating processing method and semiconductor structure, which solves the problems of uneven filling and poor surface morphology of titanium nitride thin films in high aspect ratio patterned deep hole structures in the prior art, as well as the resulting poor thin film electrical properties and reduced device reliability.

[0009] To achieve the above objectives, the present invention provides a furnace tube-type titanium nitride deposition and etching alternating process, comprising the following steps: Step S1: Provide a semiconductor wafer with a patterned deep hole structure on its surface; Step S2: A first titanium nitride deposition is performed on the wafer surface to form a titanium nitride layer with a predetermined partial thickness. Step S3: Under plasma conditions, the titanium nitride layer is etched back using an etching gas, which includes a fluorine-containing gas, nitrogen, and oxygen. Step S4: Perform a second titanium nitride deposition on the etched wafer surface; Step S5: Steps S3 and S4 are combined to form a deposition-etching alternating cycle. The deposition-etching alternating cycle is repeated until a preset cutoff condition is met, and the cycle is terminated to form a titanium nitride thin film of the target thickness.

[0010] In some embodiments, in step S3, the fluorine-containing gas is carbon tetrafluoride and / or nitrogen trifluoride.

[0011] In some embodiments, in step S3, the etching gas consists of carbon tetrafluoride, nitrogen, and oxygen; Alternatively, it can be composed of nitrogen trifluoride, nitrogen gas, and oxygen. Alternatively, it can be composed of carbon tetrafluoride, nitrogen trifluoride, nitrogen, and oxygen.

[0012] In some embodiments, the number of deposition-etching cycles is determined based on the size of the patterned deep hole structure.

[0013] In some embodiments, the deposition-etching cycle is performed 1-5 times.

[0014] In some embodiments, the preset cutoff condition is: the total thickness of the titanium nitride layer on the wafer surface reaches a preset target thickness.

[0015] In some embodiments, the titanium nitride deposition in step S2 and / or step S4 is an atomic layer deposition process.

[0016] In some embodiments, step S3 employs isotropic etching to enlarge the gaps in the patterned deep hole structure.

[0017] In some embodiments, the etching amount of the back etching in step S3 is within a first preset etching ratio range relative to the thickness of the titanium nitride layer deposited in the preceding deposition step. The preceding deposition step is step S2, or step S4 in the previous deposition-etching alternation cycle.

[0018] In some embodiments, in step S3, the volume flow rate ratio of nitrogen to fluorine-containing gas is a first preset flow rate ratio range; and / or, the volume flow rate ratio of oxygen to fluorine-containing gas is a second preset flow rate ratio range.

[0019] In some embodiments, during the deposition-etching alternating cycle, the filling status of the patterned deep hole structure is monitored in real time using optical emission spectroscopy.

[0020] In some embodiments, step S1 further includes a wafer preprocessing process: The wafer is soaked in an acid solution to remove the oxide layer on the wafer surface; Rinse the wafer with a cleaning solution; The wafer surface and the interior of the patterned deep holes are dried by blowing gas.

[0021] To achieve the above objectives, the present invention provides a semiconductor structure comprising: Semiconductor wafers with patterned deep hole structures on their surface; A titanium nitride thin film is formed on the inner wall of the patterned deep hole structure and on the surface of the semiconductor wafer; The titanium nitride thin film is prepared by the furnace tube titanium nitride deposition and etching alternating process described above.

[0022] This invention provides a furnace tube-type titanium nitride deposition and etching alternating processing method and semiconductor structure. By introducing a specific combination of fluorine-containing gas, nitrogen and oxygen in the back etching step and optimizing the deposition-etching cycle process, the size loading effect is effectively suppressed. This results in the deposition of high-quality titanium nitride thin films with smooth surfaces, uniform thickness and no gap defects in high aspect ratio patterned deep hole structures, significantly improving the performance and reliability of semiconductor devices. Attached Figure Description

[0023] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features, wherein: Figure 1 A schematic diagram of the initial morphology of the wafer surface before the implementation of the process in the prior art is shown; Figure 2 A schematic diagram of the post-deposition morphology of an existing process using simple deposition is shown. Figure 3 This diagram illustrates the morphology of a TiN film deposited to half its thickness in the prior art. Figure 4 Reveals the use of N in existing technologies Schematic diagram of the morphology after gas back etching; Figure 5 This diagram illustrates the morphology after redeposition in the prior art. Figure 6 A step diagram of a furnace tube titanium nitride deposition and etching alternating process according to an embodiment of the present invention is disclosed; Figure 7 A schematic diagram of the initial morphology of a wafer surface according to an embodiment of the present invention is disclosed; Figure 8 A schematic diagram of the morphology after the first titanium nitride deposition according to an embodiment of the present invention is shown; Figure 9 A schematic diagram of the morphology after etching back using etching gas is shown according to an embodiment of the present invention; Figure 10 A schematic diagram of the morphology of the final titanium nitride thin film formed according to an embodiment of the present invention is shown. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0025] This invention proposes a furnace-type titanium nitride (TiN) deposition and etching alternating process, involving an improved deposition-etching alternating process and supporting gas combination for a furnace-type multi-wafer titanium nitride deposition machine, to deposit high-quality titanium nitride thin films within patterned deep-hole structures of semiconductor wafers. This process significantly reduces the uneven deposition rate problem caused by the loading effect in traditional deposition-etching alternating processes, thereby obtaining thin films with smoother surfaces and better uniformity.

[0026] Figure 6 A step diagram of a furnace-tube titanium nitride deposition and etching alternating process according to an embodiment of the present invention is disclosed, as follows: Figure 6 As shown, this invention proposes a furnace tube-type titanium nitride deposition and etching alternating processing method, comprising the following steps: Step S1: Provide a semiconductor wafer with a patterned deep hole structure on its surface; Step S2: A first titanium nitride deposition is performed on the wafer surface to form a titanium nitride layer with a predetermined partial thickness. Step S3: Under plasma conditions, the titanium nitride layer is etched back using an etching gas, which includes a fluorine-containing gas, nitrogen, and oxygen. Step S4: Perform a second titanium nitride deposition on the etched wafer surface; Step S5: Steps S3 and S4 are combined to form a deposition-etching alternating cycle. The deposition-etching alternating cycle is repeated until a preset cutoff condition is met, and the cycle is terminated to form a titanium nitride thin film of the target thickness.

[0027] The present invention proposes a furnace tube-type titanium nitride deposition and etching alternating processing method. By introducing a specific combination of fluorine-containing gas, nitrogen and oxygen in the back etching step of step S3 and optimizing the deposition-etching cycle process, the size loading effect during the etching process is effectively suppressed, and the goal of high-quality titanium nitride film deposition is finally achieved.

[0028] These steps will be described in detail below. It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined and related to each other to form preferred technical solutions.

[0029] The core of step S1 lies in providing a semiconductor wafer with a patterned deep-hole structure as a process substrate. Specifically, after the wafer has undergone wafer fabrication, its surface has been formed with microstructures such as holes or trenches with high aspect ratios.

[0030] Figure 7 A schematic diagram of the initial morphology of a wafer surface according to an embodiment of the present invention is disclosed, such as... Figure 7As shown, before deposition, the semiconductor wafer 201 with patterned deep hole structure has completed the necessary front-end processes and is in a clean state, suitable for titanium nitride (TiN) deposition process, with no significant impurities or defects on the surface.

[0031] Optionally, this step may also include a wafer pretreatment process to further improve substrate quality and ensure subsequent deposition results. This wafer pretreatment process includes: The wafer is immersed in an acid solution to efficiently remove the natural oxide layer on the wafer surface; Rinse the wafer thoroughly with cleaning solution to completely remove residual acid and surface impurities; The wafer surface and the inside of the patterned deep holes are dried by blowing gas to avoid moisture or contaminant residue; The acid solution is a diluted hydrofluoric acid solution, the cleaning solution is deionized water, and the purging gas is nitrogen.

[0032] In actual processes, other reagents and gases with similar functions can be used depending on equipment conditions and process requirements. For example, acid solutions can be dilute hydrochloric acid, buffer oxide etchants, etc., cleaning solutions can be ultrapure water or alcohol solvents, and purging gases can be argon or other inert gases.

[0033] In step S2, a first titanium nitride deposition is performed on the wafer surface to form a titanium nitride layer with a predetermined partial thickness, as detailed below: This step uses atomic layer deposition (ALD) to perform the first titanium nitride deposition.

[0034] The ALD process is based on sequential, self-limiting surface chemical reactions, achieved by alternately introducing titanium source precursors (such as titanium tetrachloride, TiC). ) and nitrogen source precursors (such as ammonia N) This process enables atomic-level thin film growth on the wafer surface. It offers excellent step coverage and thickness control precision, making it particularly suitable for deposition within high aspect ratio structures.

[0035] Figure 8 A schematic diagram of the morphology after the first titanium nitride deposition according to an embodiment of the present invention is shown, such as... Figure 8 As shown, due to the loading effect, the larger the pore size of the deep hole structure, the higher the reactant transport efficiency and the faster the deposition rate. This results in a relatively larger titanium nitride film 202 deposition thickness at the top of the large pore, which is prone to forming local deposition protrusions. Furthermore, an incompletely closed initial gap can be faintly seen in the central region of the pore.

[0036] In step S3, under plasma conditions, an etching gas including fluorine-containing gas, nitrogen, and oxygen is used to perform a back etching of the titanium nitride layer.

[0037] Specifically, in a plasma environment, the aforementioned mixed etching gas (e.g., C) is introduced into the reaction chamber. / / The etching process employs an isotropic etching method. This method preferentially removes the protruding portions of the orifices and the sidewalls of the gaps within the patterned deep hole structure, thereby widening the narrow gaps into more easily filled V-shaped openings and creating a uniform base morphology for subsequent deposition.

[0038] Figure 9 This illustration shows a schematic diagram of the morphology after etching with etching gas in one embodiment of the present invention, as shown below. Figure 9 As shown, thanks to nitrogen ( ) and oxygen ( With the coordinated regulation of ), the etching process is carried out uniformly in patterned regions of different sizes. The narrow gaps in the patterned deep hole structure are widened into V-shaped openings that are easier to fill. This effectively solves the loading effect problem of "the larger the hole diameter, the slower the etching rate" that exists in traditional single fluorine gas etching, and finally obtains a titanium nitride layer 203 with a uniform thickness.

[0039] The fluorine-containing gas is carbon tetrafluoride (C6). ) and / or nitrogen trifluoride (N The etching gas specifically employs one of the following combinations to replace the traditional pure N2O. Etching gas: Carbon tetrafluoride (C) Nitrogen and oxygen composition; Alternatively, from nitrogen trifluoride N Nitrogen and oxygen composition; Alternatively, it can be made from carbon tetrafluoride (C). Nitrogen trifluoride (N) Nitrogen and oxygen composition.

[0040] That is, fluorine-containing gases can be produced by C Provided separately, N Available separately, or C With N Provided mixed in any proportion. It should be noted that nitrogen ( ) and oxygen ( All of these are necessary components and must be combined with fluorine-containing gas to form a reaction system; if any one of them is missing, the uniform etching effect required by this invention cannot be achieved.

[0041] The mechanism of the etching method of this invention is analyzed as follows: the etching dominated by fluorine radicals is essentially isotropic etching, while traditional single fluorine-based gases (such as N2) are... The fluorine radical etching produced is a strong isotropic reaction, and its rate is strongly dependent on the mass transfer rate of reactants and products. Therefore, a rate difference is generated in regions with different opening sizes. Large opening regions have sufficient reactant replenishment and faster etching rate, while narrow regions have obstructed reactant transport and slower etching rate, eventually forming obvious surface unevenness, which is the loading effect.

[0042] Nitrogen ( ) and oxygen ( The addition of [a specific ingredient] transforms the etching reaction into a self-limiting reaction, promoting a uniform etching rate across different regions and effectively suppressing the size loading effect. The specific mechanism is as follows: In this embodiment, nitrogen ( The role of nitrogen in a plasma environment is that it can promote the dissociation of oxygen and participate in the formation of strong oxidizing substances (such as NO). These species do not simply form nitride layers, but rather enhance the oxidation process on the TiN surface, transforming TiN etching into a reaction-limited process, similar to the mechanism of atomic layer etching (ALE). This transformation slows down the TiN etching rate while making the etching depth no longer affected by byproduct removal efficiency or trench size. Essentially, it modulates etching from a rapid, non-equilibrium reaction into a self-limiting process constrained by surface reactions, ultimately making the etching rates of patterned regions of different sizes more uniform and significantly suppressing size loading effects.

[0043] At the same time, the introduction of nitrogen may also promote the etching byproducts from Ti. Transformed into more volatile Ti This material further reduces exhaust load and structural dependence, improving the overall uniformity and process stability of etching.

[0044] In this embodiment, oxygen ( The role of oxygen is that it participates in the reaction and promotes the oxidation process, which may generate intermediates such as oxygen-containing fluorides. Together with nitrogen, it regulates the plasma chemical environment, balances the oxidation and nitriding processes, and further optimizes the etching uniformity and selectivity.

[0045] In this embodiment, C / N Fluorine serves as the fluorine source in the etching process, providing the necessary core capabilities for the etching reaction; nitrogen mainly plays a role in inhibiting the reaction and homogenizing the rate; oxygen helps to balance the reaction environment. The three work synergistically to jointly regulate the selectivity and uniformity of the etching reaction, thereby fundamentally suppressing the generation of size loading effects.

[0046] Furthermore, the etching amount in step S3 is within a first preset etching ratio range relative to the thickness of the titanium nitride layer deposited in the preceding deposition step (step S2 or step S4 in the previous cycle). The preceding deposition step is step S2, or step S4 in the previous deposition-etching alternation cycle, and the first preset etching ratio ranges from 20% to 80%.

[0047] By controlling the etching amount within this range, we can ensure the effective removal of orifice protrusions and widening of initial gaps to optimize the filling morphology, while avoiding excessive etching that could expose the underlying material or damage the structure, thus preserving a uniform substrate with appropriate thickness and controllable morphology for subsequent deposition steps.

[0048] Furthermore, in step S3, the volume flow rate ratio of nitrogen to fluorine-containing gas is within a first preset flow rate ratio range; and / or, the volume flow rate ratio of oxygen to fluorine-containing gas is within a second preset flow rate ratio range. The first preset traffic ratio range is (0.5~5):1, and the second preset traffic ratio range is (0.1~2):1.

[0049] Limiting the above gas ratio range is to achieve the best synergy among fluorine radical etching, nitrogen surface passivation, and oxygen environment regulation.

[0050] In step S4, a second titanium nitride deposition is performed on the surface of the etched wafer. The specific requirements are as follows: The titanium nitride deposition in this step still uses the atomic layer deposition (ALD) process, which can be consistent with step S2 to ensure the continuity and density of the titanium nitride film and avoid film delamination or defects caused by sudden changes in process parameters.

[0051] In step S5, steps S3 and S4 are combined to form a deposition-etching alternating cycle. The deposition-etching alternating cycle is repeated until a preset cutoff condition is met, and the cycle is terminated to form a titanium nitride thin film of the target thickness.

[0052] Depending on the total thickness of the target thin film and the complexity of the deep hole structure, this cycle can be repeated 1 to 5 times (e.g., 2-3 times). The process parameters can be kept consistent for each cycle, or they can be adaptively fine-tuned based on process monitoring.

[0053] The preset cutoff condition is that the total thickness of the titanium nitride layer on the wafer surface reaches the preset target thickness. During the deposition-etching alternating cycle, the filling status of the patterned deep hole structure is monitored in real time using optical emission spectroscopy to accurately determine the process endpoint and ensure that the filling effect meets the preset requirements.

[0054] Optionally, the number of deposition-etching cycles is determined by adapting the size of the patterned deep-hole structure. Structures of different sizes (especially different pore diameters and aspect ratios) exhibit varying tendencies towards initial deposition inhomogeneities and gaps, and their morphology correction requirements for the etching step also differ. Generally, structures with smaller pore diameters and higher aspect ratios have more limited reactant transport and weaker self-adjustment capabilities in the initial deposition morphology. Therefore, more deposition-etching cycles are often required to gradually and iteratively correct the morphology, ultimately achieving defect-free filling. By correlating the number of cycles with the structure size, optimal allocation of process resources and optimization of the filling effect can be achieved.

[0055] Figure 10 A schematic diagram illustrating the morphology of the final titanium nitride thin film formed according to an embodiment of the present invention is shown. Figure 10 As shown, through the above-described complete deposition-etching alternating cycle process, a high-quality titanium nitride thin film 204 with complete filling, uniform thickness, smooth surface and no gap defects was finally formed in the patterned deep hole structure.

[0056] To further illustrate the feasibility of this invention, a specific process embodiment is provided below to exemplarily describe the process conditions and parameters of each of the above steps. This embodiment is performed in a furnace tube atomic layer deposition and plasma etching integrated apparatus suitable for multiple wafers. It is assumed that the target structure is a patterned deep hole with a aperture of 50 nm and a depth of 300 nm (aspect ratio 6:1), the total thickness of the target TiN film is sufficient to completely fill the deep hole structure, and a 12 nm capping layer is formed on the wafer surface.

[0057] First, perform step S1: pre-treat the wafer by soaking it in hydrofluoric acid to remove the natural oxide layer, rinsing it with ultrapure deionized water, and drying it with high-purity nitrogen.

[0058] Next, the first titanium nitride deposition in step S2 is performed. In a furnace-tube ALD chamber with a chamber temperature of 350–650°C, TiC is deposited... and N As a precursor, a first TiN film of approximately 4 nm thickness (about 33% of the total thickness) is deposited through approximately 50 ALD cycles. At this stage, slight protrusions may appear at the pore openings, and initial slit shapes may be formed at the center of the pores.

[0059] Subsequently, the crucial step S3 is performed: etch back. In a plasma chamber where the chamber temperature is the same as the deposition temperature, C is introduced... (100 sccm) (200 sccm) and A mixed gas of 20 sccm was used for isotropic etching at 500W RF power. This step removed approximately 2nm of thickness (50% etching amount), effectively widening the gaps, smoothing the morphology, and because... and The synergistic effect of these processes resulted in uniform etching and significantly suppressed the loading effect.

[0060] Then, the second deposition in step S4 is performed. Returning to the ALD chamber, the same process conditions as in step S2 are used to perform approximately 50 cycles to deposit a second TiN film approximately 5 nm thick.

[0061] Finally, cycle control is performed via step S5: steps S3 and S4 above are defined as a deposition-etching alternating cycle. For this example structure, this cycle is executed twice. During the process, the filling status is monitored using optical emission spectroscopy, and the process terminates when the total film thickness reaches the target value of 12 nm, completely filling the deep hole structure and forming on the wafer surface.

[0062] By implementing the above parameters, a high-quality titanium nitride film with complete filling, uniform thickness, smooth surface, and no gaps was finally obtained within a structure with an aspect ratio of 6:1. This embodiment demonstrates the feasibility of synergistically suppressing the loading effect and optimizing film filling by controlling key parameters such as gas ratio, etching amount, and cycle number.

[0063] In summary, this invention provides a novel furnace-tube titanium nitride deposition-etching-deposition process, which replaces the traditional single nitrogen gas with a composite gas combination of fluorine-containing gas, nitrogen, and oxygen. Etching gas effectively mitigates the size loading effect during the re-etching process, significantly improving the deposition quality of titanium nitride films.

[0064] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0065] Based on the above method, this embodiment also provides a semiconductor structure, specifically including a semiconductor wafer and a titanium nitride thin film: The surface of the semiconductor wafer is formed with a patterned deep hole structure. The patterned deep hole structure can be a high aspect ratio contact hole, through hole, trench, or a combination thereof, and its size and morphology can be determined according to the specific device design requirements.

[0066] The titanium nitride thin film is formed on the inner walls (including the sidewalls and bottom) of the patterned deep hole structure and on the surface of the semiconductor wafer. This film can serve as a conductive functional layer, such as a capacitor electrode, gate, or contact / via barrier layer.

[0067] The titanium nitride thin film is prepared by the above-mentioned furnace tube titanium nitride deposition and etching alternating process, ensuring that the surface flatness, thickness uniformity and electrical properties of the titanium nitride thin film meet the preset technical requirements.

[0068] The semiconductor structure proposed in this invention effectively overcomes the problem of thin film inhomogeneity caused by loading effect and gap residue in traditional processes. It has the characteristics of strong structural stability and high reliability, and can be widely used in the manufacturing of semiconductor devices at different technology nodes, adapting to diverse functions and application scenarios.

[0069] It is understood that the above embodiments are merely one specific implementation of the present invention. Without departing from the scope defined by the present invention, those skilled in the art can make adjustments according to actual process requirements. For example, the size, shape, and distribution density of the patterned deep hole structure can be varied; the specific process parameters for deposition and etching can be optimized within the scope defined in the claims; and the semiconductor structure can be further integrated into more complex device stacks.

[0070] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0071] The above embodiments are provided for those skilled in the art to implement or use the present invention. Those skilled in the art can make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the protection scope of the present invention is not limited to the above embodiments, but should be the maximum scope that conforms to the innovative features mentioned in the claims.

Claims

1. A method for alternating deposition and etching of titanium nitride in a furnace tube, characterized in that, Includes the following steps: Step S1: Provide a semiconductor wafer with a patterned deep hole structure on its surface; Step S2: A first titanium nitride deposition is performed on the wafer surface to form a titanium nitride layer with a predetermined partial thickness. Step S3: Under plasma conditions, the titanium nitride layer is etched back using an etching gas, which includes a fluorine-containing gas, nitrogen, and oxygen. Step S4: Perform a second titanium nitride deposition on the etched wafer surface; Step S5: Steps S3 and S4 are combined to form a deposition-etching alternating cycle. The deposition-etching alternating cycle is repeated until a preset cutoff condition is met, and the cycle is terminated to form a titanium nitride thin film of the target thickness.

2. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, In step S3, the fluorine-containing gas is carbon tetrafluoride and / or nitrogen trifluoride.

3. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, The number of deposition-etching cycles is determined according to the size of the patterned deep hole structure, and the number of deposition-etching cycles is 1-5.

4. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, The preset cutoff condition is: the total thickness of the titanium nitride layer on the wafer surface reaches the preset target thickness.

5. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, The titanium nitride deposition in step S2 and / or step S4 is an atomic layer deposition process.

6. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, Step S3 employs isotropic etching to enlarge the gaps in the patterned deep hole structure.

7. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, The etching amount in step S3 is within a first preset etching ratio range relative to the thickness of the titanium nitride layer deposited in the previous deposition step. The preceding deposition step is step S2, or step S4 in the previous deposition-etching alternation cycle.

8. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, During the alternating deposition-etching cycle, the filling status of the patterned deep hole structure is monitored in real time using optical emission spectroscopy.

9. The furnace tube-type titanium nitride deposition and etching alternating processing method according to claim 1, characterized in that, Step S1 further includes a wafer preprocessing process: The wafer is soaked in an acid solution to remove the oxide layer on the wafer surface; Rinse the wafer with a cleaning solution; The wafer surface and the interior of the patterned deep holes are dried by blowing gas.

10. A semiconductor structure, characterized in that, include: Semiconductor wafers with patterned deep hole structures on their surface; A titanium nitride thin film is formed on the inner wall of the patterned deep hole structure and on the surface of the semiconductor wafer; The titanium nitride thin film is prepared by the furnace tube titanium nitride deposition and etching alternating process as described in any one of claims 1 to 9.

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