Bottom-up selective fill method and semiconductor structure

Abstract

This application relates to the field of semiconductor manufacturing technology, and provides a bottom-up selective filling method and semiconductor structure. The method includes: providing a substrate with a recessed structure; forming a conductive liner layer at the bottom of the recessed structure; and selectively depositing a filler material from bottom to top on the conductive liner layer to form a filler layer that fills the recessed structure. Embodiments of this application can eliminate or avoid the problem of structural bending deformation caused by the mutual attraction of Casimir forces in the recessed structure.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a bottom-up selective filling method and semiconductor structure. Background Technology

[0002] As the size of semiconductor devices continues to shrink, metal filling of three-dimensional high aspect ratio structures (such as trenches in FinFETs and 3D NAND) has become a critical process. Existing technologies typically employ atomic layer deposition (ALD) or chemical vapor deposition (CVD) for conformal metal filling, where a seed layer is conformally deposited on the bottom and sidewalls of the recessed structure before the main metal is deposited. However, in this conformal filling process, when metal layers on adjacent sidewalls approach each other at the nanoscale, an attractive force arises, leading to structural bending deformation (zipping effect), which affects device reliability. Summary of the Invention

[0003] The purpose of this application is to provide a bottom-up selective filling method and semiconductor structure to alleviate or eliminate the above-mentioned problems.

[0004] To achieve the above objectives, in one aspect, embodiments of this application provide a bottom-up selective filling method, including: Provide a substrate with a recessed structure; A conductive liner layer is formed at the bottom of the recessed structure; A filler material is selectively deposited from bottom to top on the conductive liner layer to form a filler layer that fills the recessed structure.

[0005] In some embodiments of this application, the resistivity of the filler material is lower than that of the conductive liner layer.

[0006] In some embodiments of this application, forming a conductive liner layer at the bottom of the recessed structure includes: A conductive liner layer is conformally deposited on the surface of the recessed structure; The conductive liner layer on the top and sidewalls of the recessed structure is selectively etched to retain the conductive liner layer at the bottom of the recessed structure.

[0007] In some embodiments of this application, at least two of the conformal deposition, the selective etching, and the selective deposition share the same reaction chamber and / or employ at least partially the same homologous material system.

[0008] In some embodiments of this application, the selective etching of the conductive liner layer on the top and sidewalls of the recessed structure includes: Etching gas is pulsed into the recessed structure to cause a chemical reaction between the surface of the conductive liner layer and the etching gas, generating volatile products at a rate decreasing from top to bottom. The volatile products and residual etching agent after the reaction were purged with purge gas; Repeat the etching steps described above to gradually remove the conductive liner layer on the top and sidewalls of the recessed structure.

[0009] In some embodiments of this application, the step of pulsedly introducing etching gas into the recessed structure includes: The etching gas is introduced into the recessed structure based on a set introduction time, so that the concentration of the etching gas in the recessed structure decreases from top to bottom, and the introduction time is 0.1 to 5 seconds.

[0010] In some embodiments of this application, before pulsed introduction of etching gas into the recessed structure, the method further includes: Using inert gas as a carrier gas, a predetermined amount of etching gas is carried from the source gas source to the buffer gas source, which forms the pulsed supply source.

[0011] In some embodiments of this application, the selective deposition of filler material from bottom to top on the conductive liner layer includes: A metal precursor is introduced into the recessed structure, so that the metal precursor is adsorbed onto the surface of the conductive liner layer. The metal precursors that were not adsorbed onto the surface of the conductive liner layer within the recessed structure were purged with purge gas. A reducing agent is introduced into the recessed structure to cause the reducing agent to chemically react with the metal precursor adsorbed on the surface of the conductive liner layer, and to form a filling layer on the surface of the conductive liner layer. Use purge gas to purge the remaining reducing agent and reaction byproducts after the reaction; Repeat the above deposition steps until a filling layer is formed from bottom to top, filling the depression structure.

[0012] In some embodiments of this application, during the selective deposition of filler material on the conductive liner layer from bottom to top, the temperature of the cavity containing the recessed structure is 300°C to 600°C.

[0013] On the other hand, this application embodiment also provides a semiconductor structure obtained based on the above method, the semiconductor structure including a substrate with a groove structure, the groove structure including a bottom and sidewalls, the bottom of the groove structure being covered with a conductive liner layer, and the remaining part of the groove structure being filled with a filling layer.

[0014] As can be seen from the technical solutions provided by the above embodiments of this application, in the embodiments of this application, a conductive lining layer is formed only at the bottom of the recessed structure, that is, there is no conductive lining layer at the top and sidewalls of the recessed structure. The conductive layer (filling layer) is selectively filled from the bottom of the recessed structure from bottom to top, thereby fundamentally eliminating or avoiding the problem of structural bending deformation caused by the mutual attraction between adjacent conductive layers on the sidewalls of the recessed structure due to the Casimir force. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 A schematic diagram illustrating the structural bending deformation of a recessed structure in the prior art is shown; Figure 2 A flowchart of a bottom-up selective filling method in some embodiments of this application is shown; Figure 3 This document illustrates a flowchart of forming a conductive liner layer at the bottom of a recessed structure in some embodiments of this application. Figure 4 A flowchart illustrating the conductive liner layer of the top and sidewalls of the selectively etched recessed structure in some embodiments of this application is shown. Figure 5 This document illustrates a flowchart of the deposition of filler material on a conductive liner layer in some embodiments of this application; Figure 6 This application shows schematic diagrams of material filling processes for semiconductor manufacturing in some embodiments; Figure 7 A schematic diagram of a semiconductor structure in some embodiments of this application is shown.

[0016] [Explanation of Labels in the Attached Image]

[0017] 10. Base; 11. Depressed structure; 12. Conductive lining layer; 13. Fill layer. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0019] In semiconductor manufacturing, high aspect ratio structures are primarily filled using conformal deposition (or conformal filling) processes. Thermal stress mismatch or surface effects during conformal deposition can easily induce the zipping effect. This occurs when two relatively parallel metal surfaces approach each other, the resulting long-range attraction causes the structure to move closer together and bend, ultimately leading to structural deformation. At the micro-nano scale, the Casimir force, as an important surface effect, is a long-range attraction caused by zero-point fluctuations in the vacuum electromagnetic field. Its magnitude is inversely proportional to the fourth power of the distance between the surfaces (∝1 / d). 4 ).like Figure 1 As shown, when metal is conformally deposited in a narrow gap and the two surfaces are extremely close (e.g., as small as tens of nanometers or even smaller), the attraction will act as a significant distributed load on the structure, changing its mechanical equilibrium, exacerbating the zipper effect, and thus causing the structure to bend.

[0020] In view of this, embodiments of this application provide a novel bottom-up selective filling method to alleviate or eliminate the aforementioned structural deformation problems. The material filling method of this application embodiment can be performed by equipment used in semiconductor manufacturing. In some embodiments of this application, the equipment used in semiconductor manufacturing may include, but is not limited to: atomic layer deposition / etching equipment (ALD / ALE), chemical vapor deposition / etching equipment (CVD / RIE), cluster tool, high aspect ratio dedicated equipment, or other semiconductor manufacturing equipment with functions such as deposition, etching, and co-cavity integration. The technical solutions of this application can be widely applied in multiple fields such as semiconductor manufacturing (front-end, back-end, memory), advanced packaging, MEMS / sensors, quantum computing, flexible electronics, and biosensors.

[0021] For ease of description, some embodiments of this specification use spatially relative terms such as "top," "bottom," "bottom-up," "top-down," and "on top of" to describe the spatial positional relationship between one element and another as shown in the accompanying drawings. This description is exemplified by a base with a recessed structure that has an upper opening and is not longitudinally penetrating (i.e., the recessed structure has a bottom), intended to describe the orientation of the base with the recessed structure when it is manipulated. It should be understood that the recessed structure can be any other suitable orientation besides that described in the drawings. For example, if the base with the recessed structure in the drawings is flipped, an element described as "on top of" can be positioned as "below top of," and an element described as "bottom-up" can be positioned as "top-down."

[0022] refer to Figure 2 As shown, in some embodiments of this application, the bottom-up selective filling method may include the following steps: Step 201: Provide a substrate with a recessed structure.

[0023] Step 202: Form a conductive lining layer at the bottom of the recessed structure.

[0024] Step 203: Selectively deposit filler material from bottom to top on the conductive liner layer to form a filler layer that fills the recessed structure.

[0025] In the embodiments of this application, a conductive lining layer is formed only at the bottom of the recessed structure, that is, there is no conductive lining layer at the top and sidewalls of the recessed structure. The conductive layer (filling layer) is selectively filled from the bottom of the recessed structure from bottom to top, thereby fundamentally eliminating or avoiding the problem of structural bending deformation caused by the mutual attraction between adjacent conductive layers on the sidewalls of the recessed structure due to the Casimir force.

[0026] Furthermore, in traditional conformal deposition processes, since the sidewalls and bottom of the recessed structure are covered with conductive liner layers, multiple growth fronts are formed when the material grows simultaneously at the bottom and sidewalls during material filling. When the growth front of the sidewall makes premature contact with the top, it cuts off the channel for reactant diffusion to the bottom, creating a pinch-off effect. Ultimately, this makes the fill layer prone to defects such as voids or seams due to the pinch-off effect. However, in the embodiments of this application, since the sidewalls of the recessed structure do not have conductive liner layers, there is no pinch-off effect caused by premature contact of the sidewall growth front. As long as growth continues from the bottom up, the metal layer will grow layer by layer until the entire recessed structure is filled, thereby reducing or avoiding the problem of voids or seams easily formed in the fill layer. Thus, it achieves the elimination of structural bending deformation caused by the mutual attraction of Casimir forces while reducing or avoiding the problem of voids or seams easily formed in the fill layer.

[0027] In some embodiments of this application, the resistivity of the filler material is lower than that of the conductive liner layer. Conformal deposition processes typically require the deposition of a conductive liner layer on the overall inner surface; these materials are often high-resistivity metal nitrides. As device dimensions continue to shrink, the proportion of the conductive liner layer required for conformal metal filling in the overall space increases significantly, while the volume of the highly conductive metal decreases, leading to a sharp increase in overall interconnect resistance and severely impacting the device's electrical performance and signal transmission efficiency. In some embodiments of this application, since the resistivity of the filler material is lower than that of the conductive liner, when the filler layer is selectively deposited from bottom to top on the conductive liner located only at the bottom of the recessed structure, the high-resistivity conductive liner is only retained at the bottom of the recessed structure, and the proportion of the high-resistivity conductive liner in the overall space of the recessed structure is very small. This reduces the proportion of high-resistivity material in the conductive cross-sectional area of ​​the recessed structure, that is, reduces the conduction resistance of the structure. In this way, while eliminating the structural bending deformation caused by the mutual attraction of Casimir forces, the problem of voids or seams easily generated in the filler layer is reduced or avoided, and the problem of increased conduction resistance mentioned above is alleviated or eliminated.

[0028] A recessed structure refers to a three-dimensional structure formed on the surface of a substrate and having an opening, sidewalls, and a bottom, such as a groove or letter groove. In some embodiments of this application, the substrate with a recessed structure can refer to a substrate with a high aspect ratio. In a high aspect ratio recessed structure, the aspect ratio (the ratio of recess depth to recess width) can be greater than 5:1, and can even reach 10:1, 50:1, or higher.

[0029] In some embodiments of this application, the substrate material may include, but is not limited to, Si, SiGe, SiO2, and AlO. x (Aluminum oxide, where x represents the number of oxygen atoms), SiN, ZrO x HfO x (Hafnium oxide, where x represents the number of oxygen atoms) and any combination of one or more of these materials. It is understood that the substrate material is not limited to the above-listed materials; any material suitable for semiconductor processes can be used.

[0030] In some embodiments of this application, the conductive liner layer may be a metal layer with high resistivity, such as a seed layer. The seed layer primarily provides nucleation sites for subsequent metal material filling, enhances adhesion, and reduces contact resistance, thereby forming a conductive, low-barrier, and highly adhesive surface, facilitating stable and uniform subsequent metal material filling.

[0031] Combination Figure 3 As shown, in some embodiments of this application, forming a conductive liner layer at the bottom of the recessed structure may include the following steps: Step 301: Conformally deposit a conductive liner layer on the surface of the recessed structure.

[0032] Step 302: Selectively etch the conductive liner layer on the top and sidewalls of the recessed structure to retain the conductive liner layer at the bottom of the recessed structure.

[0033] Figure 3 The method shown for forming a conductive liner layer at the bottom of the recessed structure has no requirements or restrictions on the combination of the conductive liner layer and the filler layer, and has strong universality.

[0034] In some embodiments of this application, a conductive liner layer can be formed on the surface of the recessed structure based on conformal deposition processes such as atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD).

[0035] For example, in one exemplary embodiment, taking atomic layer deposition (ALD) seed layer as an example, a substrate with a recessed structure can be placed in an ALD reaction chamber, and the chamber temperature can be maintained at a suitable temperature, such as 300–600°C, to prevent incomplete reaction due to excessively low temperature or thermal decomposition due to excessively high temperature, which may introduce unintended components; molybdenum dioxide (MoO2Cl2) is used as a metal precursor, and the origin of MoO2Cl2 is heated and maintained at 120°C to ensure that MoO2Cl2 has a stable vapor pressure and avoid decomposition or condensation; ammonia (NH3) is used as a co-reacting gas; and argon (Ar) is used as a purge gas, and the following ALD cycle is performed: a1. MoO2Cl2 vapor is introduced into the cavity in a pulsed manner for 0.5 to 10 seconds to allow it to diffuse fully and be adsorbed onto the substrate surface. b1. Use argon gas to purge the chamber for more than 2 seconds to remove excess metal precursors and byproducts. c1. NH3 is pulsed into the cavity for 3–15 s at a flow rate of 1000–30000 sccm to react with the adsorbed MoO2Cl2 to generate MoN as a seed layer. The 3–15 s pulse duration of NH3 provides sufficient reaction time to ensure complete nitriding. The flow rate of 1000–30000 sccm ensures that there is still sufficient concentration at the bottom of the recessed structure to promote uniform reaction. d1. Purge the reaction chamber with argon gas for more than 2 seconds to remove excess NH3 and byproducts.

[0036] e1. Repeat steps a1 to d1 above, controlling the seed layer thickness by controlling the number of cycles, to form a conformally covering MoN seed layer on the bottom, sidewalls, and top of the recessed structure. When the seed layer thickness is 5–50 Å, continuous coverage and sufficient etching allowance can be ensured, while reducing the proportion of high-resistivity material and the subsequent etching burden.

[0037] like Figure 6 As shown, the substrate 10 with the recessed structure 11 (such as...) Figure 6 (As shown in the first figure from the left in the middle), a conductive liner layer 12 can be formed on the surface (top, sidewalls, and bottom) of the recessed structure 11 through conformal deposition (as shown in the first figure from the left in the middle). Figure 6 (The second attached figure from the left in the middle).

[0038] Combination Figure 4 As shown, in some embodiments of this application, selectively etching the conductive liner layer on the top and sidewalls of the recessed structure may include the following steps: Step 401: The etching gas is pulsed into the recessed structure so that the surface of the conductive liner layer reacts chemically with the etching gas, and volatile products are generated at a rate decreasing from top to bottom.

[0039] Step 402: Use purge gas to purge the volatile products and the etching agent remaining after the reaction.

[0040] Step 403: Repeat the above etching steps to gradually remove the conductive liner layer on the top and sidewalls of the recessed structure.

[0041] exist Figure 4 In the illustrated embodiment, the etching gas forms a top-to-bottom concentration gradient within the recessed structure due to diffusion limitations, resulting in the highest concentration at the top and the lowest concentration at the bottom. This creates an etching rate distribution with the fastest rate at the top, followed by the sidewalls, and the slowest rate at the bottom in a single etching cycle. By precisely controlling the number of etching cycles, the cumulative etching amount at the top and sidewalls is exactly equal to their initial thickness and is completely removed. Since the bottom has the slowest etching rate, a portion of the thickness remains after the same number of cycles, thus achieving the goal of retaining only the bottom conductive liner layer. This process requires no complex masks, is simple, and offers high controllability.

[0042] In some embodiments of this application, the etching gas is pulsedly introduced into the recessed structure, which may include: introducing the etching gas into the recessed structure based on a set introduction duration, so that the etching gas concentration in the recessed structure decreases from top to bottom. In an exemplary embodiment, the introduction duration may be, for example, 0.1 to 5 seconds; thus, by controlling the introduction duration to 0.1 to 5 seconds, the diffusion depth and adsorption saturation of the etching gas in the recessed structure can be effectively adjusted, thereby forming a suitable etching gas concentration gradient (decreasing from top to bottom), so that the top reaches saturated adsorption of the etching gas (maximum etching amount), while the bottom has no adsorption or very little adsorption (minimum etching amount).

[0043] In some embodiments of this application, the chemical reaction between the etching gas and the conductive liner can be a chemical displacement reaction or a redox reaction. Essentially, it reacts the conductive liner to generate volatile substances, thereby converting the solid conductive liner into a gaseous substance, so that it can be easily removed or cleaned later.

[0044] In some embodiments of this application, an inert gas (e.g., argon) can be used to purge (purge time greater than 2 seconds) volatile products and residual etchant after the reaction to thoroughly remove etchant and byproducts, ensure atomic-level cleanliness of the interface, and prevent residual etchant from mixing in and interfering with the selective growth of subsequent deposited filling layers.

[0045] In some embodiments of this application, before pulsedly introducing the etching gas into the recessed structure, a predetermined amount of etching gas can be carried from the source gas source to a buffer gas source using an inert gas as a carrier gas. The buffer gas source forms the direct supply source for the pulsed introduction. This allows for the establishment of a more stable and controllable etching gas concentration, improving the accuracy of dosage control during pulsed introduction and providing a favorable foundation for the subsequent precise and selective removal of the conductive liner layer. The source gas source can be a high-pressure gas source, and the buffer gas source can be a buffer container.

[0046] In some embodiments of this application, the conductive liner layer can be a metal seed layer. The material of the metal seed layer includes, but is not limited to, one or more combinations of metals, metal nitrides, and metal silicides. For example, in some embodiments of this application, the material of the metal seed layer includes one or more combinations of MoN, TiN, MoSi, TiSi, Ru, Co, W, and Mo. In some embodiments of this application, the etching gas includes a gaseous etchant or plasma generated from a gaseous etchant. Unlike etching liquids, which tend to accumulate at the bottom and are difficult to form a top-to-bottom decreasing concentration distribution of the etchant in the recessed structure, the embodiments of this application, by selecting an etching gas, more easily achieve precise control over the formation of a top-to-bottom decreasing concentration distribution of the etchant in the recessed structure.

[0047] In some embodiments of this application, the etching gas includes a metal chloride etchant, such as MoCl5 or WCl5.

[0048] In an exemplary embodiment of this application, MoCl5 is used as the metal precursor, and argon is used as the carrier gas and purge gas to etch the seed layer (which serves as the conductive liner layer) on the top and sidewalls. The source temperature of MoCl5 is 100°C, and the substrate film is MoN. The structure sheet (i.e., the recessed structure) with the conformally deposited seed layer is placed in the ALD cavity, with the cavity temperature at 300°C to 600°C and the cavity pressure at 10 torr to 80 torr, and etching is started according to the following steps. Controlling the cavity temperature to 300°C to 600°C and the cavity pressure to 10 torr to 80 torr allows for the coordinated regulation of the reaction rate and gas diffusion behavior during the etching process, ensuring the etching reaction rate while avoiding thermal decomposition of the etchant and substrate damage.

[0049] a2. Using argon as the carrier gas, MoCl5 vapor is carried from the source bottle to the buffer cylinder. The carrier gas introduction time is 1s to 10s, and the carrier gas flow rate is 100 to 5000 sccm. By controlling the carrier gas introduction time of 1s to 10s and the carrier gas flow rate of 100 to 5000 sccm, MoCl5 can be stably carried from the source bottle to the buffer cylinder while ensuring the required etching gas concentration and carrying efficiency. Then, MoCl5 vapor is pulsed into the chamber for 0.1s to 5s to induce a chemical reaction with the seed layer. The pulse time of 0.1s to 5s allows control over the degree of reaction between MoCl5 and MoN in each ALE cycle, achieving precise etching of a single layer or sub-single layer. b2. The chamber is purged with argon for more than 2s to remove excess MoCl5 and byproducts generated after the chemical reaction, ensuring the cleanliness of the reaction chamber.

[0050] c2. Repeat steps a2 to b2, and by controlling the number of ALE cycles, remove the seed layers from the top and sidewalls.

[0051] like Figure 6 As shown, the substrate 10 with the recessed structure 11 (such as...) Figure 6 (As shown in the first figure from the left in the middle), a conductive liner layer 12 can be formed on the surface (top, sidewalls, and bottom) of the recessed structure 11 through conformal deposition (as shown in the first figure from the left in the middle). Figure 6 (As shown in the second figure from the left in the middle); based on this, the conductive liner layer 12 of the top and sidewalls of the recessed structure 11 is selectively etched away, thereby obtaining a structure that retains only the conductive liner layer 12 at the bottom (as shown in the figure from the left in the middle). Figure 6 (The third attached figure from the left in the middle).

[0052] In other embodiments of this application, if the sidewalls and bottom of the recessed structure are made of different materials, the conductive liner layer is selective for the bottom. In this case, the conductive liner layer is formed at the bottom of the recessed structure. Alternatively, the conductive liner layer can be deposited selectively only at the bottom without conformal deposition followed by selective etching. This makes the process simpler and more efficient.

[0053] Combination Figure 5 As shown, in some embodiments of this application, selectively depositing filler material on the conductive liner layer from bottom to top may include the following steps: Step 501: Pass the metal precursor into the recessed structure so that the metal precursor is adsorbed onto the surface of the conductive liner layer.

[0054] Step 502: Use a purge gas to purge the metal precursors that are not adsorbed onto the surface of the conductive liner layer within the recessed structure.

[0055] Step 503: Pass a reducing agent into the recessed structure so that the reducing agent reacts chemically with the metal precursor adsorbed on the surface of the conductive liner layer and forms a filling layer on the surface of the conductive liner layer.

[0056] Step 504: Use purge gas to purge the remaining reducing agent and reaction byproducts after the reaction.

[0057] Step 505: Repeat the above deposition steps until a filling layer is formed from bottom to top, filling the depression structure.

[0058] exist Figure 5 In the illustrated embodiment, selective deposition refers to depositing metal material only on the conductive liner layer located at the bottom of the recessed structure. Since the metal precursor has strong chemical adsorption on the surface of the conductive liner layer and weak adsorption on the surface of the substrate medium, no sidewall growth front will appear during the bottom-up layer-by-layer filling process, thus avoiding the pinch-off effect caused by the sidewall growth front. That is, during the bottom-up layer-by-layer filling process, the filling layer only grows on the basis of the bottom conductive liner layer, thereby reducing or avoiding the problem of voids or seams that are easy to be generated during the filling process.

[0059] In some embodiments of this application, before introducing the metal precursor into the recessed structure, an etching gas of a predetermined scale can be carried from the source gas source to a buffer gas source using an inert gas as a carrier gas. The buffer gas source forms a direct supply source for the introduction of the metal precursor. Thus, by stabilizing the metal precursor dosage through the buffer gas source, the consistency of the metal precursor pulse amount in each deposition cycle is ensured, which facilitates precise control of the film thickness uniformity and the total thickness of the filling layer produced in each deposition cycle by controlling the deposition cycle.

[0060] In some embodiments of this application, the filling layer may be a metal filling layer. The material of the metal filling layer may be, for example, one or more combinations of Mo, W, Co, Ru, etc.

[0061] In some embodiments of this application, the metal precursors described above may include, but are not limited to, one or more combinations of MoO2Cl2, MoOCl4, MoCl5, MoF6, etc.

[0062] For example, in an exemplary embodiment, a seed layer is used as a conductive liner layer, MoCl5 as a metal precursor, hydrogen as a co-reacting gas, and argon as a carrier and purge gas to grow a Mo thin film, achieving bottom-up filling. The MoCl5 source temperature can be controlled at around 100°C to ensure a stable vapor pressure and controllable deposition rate for MoCl5. The substrate film is MoN. A structure sheet with only the bottom seed layer (i.e., a recessed structure) is placed in an ALD cavity with a cavity temperature of 300°C to 600°C and a cavity pressure of 10 torr to 80 torr, and deposition begins according to the following steps. During the selective deposition of the filling material on the MoN seed layer, the cavity temperature of the ALD cavity containing the recessed structure can be 300°C to 600°C to ensure that Mo grows only on the MoN seed layer, and that no or almost no nuclei are formed on the sidewalls (materials such as SiO2 and SiN); the cavity pressure can be 10 torr to 80 torr to ensure that the metal precursor diffuses sufficiently to the bottom of the recessed structure and avoids gas-phase reactions.

[0063] a3. Using argon as the carrier gas, MoCl5 vapor is carried from the source bottle to the buffer cylinder. The carrier gas introduction time is 1s to 20s, and the carrier gas flow rate is 100 to 5000 sccm. By controlling the carrier gas introduction time to 1s to 20s and the carrier gas flow rate to 100 to 5000 sccm, the precursor transport efficiency can be ensured while stably carrying MoCl5 to the buffer cylinder. Then, MoCl5 vapor is pulsed into the cavity for 0.1s to 5s to allow it to react chemically with the seed layer surface and achieve saturated adsorption.

[0064] b3. Purge the chamber with argon gas for more than 2 seconds to remove excess MoCl5 metal precursor and byproducts generated from the first chemical reaction and adsorption, keep the chamber clean, and prevent residual gas from interfering with the subsequent H2 reduction reaction.

[0065] c3. Hydrogen gas, a co-reactant, is pulsed into the chamber for 0.1–10 s at a flow rate of 100–50,000 sccm, causing it to react with the metal precursor adsorbed on the substrate surface. The 0.1–10 s pulse duration provides sufficient time for the reduction reaction to complete, while the 100–50,000 sccm flow rate ensures a sufficient H2 concentration at the bottom of the recessed structure, promoting the reaction and removing byproducts.

[0066] d3. Purge the chamber with argon gas for more than 2 seconds to remove excess co-reaction gases and byproducts of the chemical reaction and keep the chamber clean.

[0067] e3. Repeat steps a3 to d3. By controlling the number of ALD cycles, the total thickness of the metal film can be controlled (i.e., filling the recessed structure).

[0068] like Figure 6 As shown, the substrate 10 with the recessed structure 11 (such as...) Figure 6 (As shown in the first figure from the left in the middle), a conductive liner layer 12 can be formed on the surface (top, sidewalls, and bottom) of the recessed structure 11 through conformal deposition (as shown in the first figure from the left in the middle). Figure 6 (As shown in the second figure from the left in the middle); the conductive liner layer 12 on the top and sidewalls of the recessed structure 11 is selectively etched away, thereby obtaining a structure in which only the conductive liner layer 12 is retained (as shown in the figure from the left in the middle). Figure 6 (As shown in the third figure from the left in the middle); Based on this, by selectively depositing a filling material on the bottom conductive liner layer 12, a filling layer filling the recessed structure 11 can be formed (e.g., Figure 6 (The fourth attached figure from the left in the middle).

[0069] In some embodiments of this application, at least any two of the conformal deposition, selective etching, and selective deposition can share the same reaction chamber. Thus, by integrating any two or all of the conformal deposition, selective etching, and selective deposition into the same reaction chamber, the transfer of structure between multiple devices is avoided, particle contamination (atomic-level clean interface) and vacuum damage are prevented, process efficiency and yield are improved, and the synergistic effect of extreme process simplification and precise control of surface condition is achieved.

[0070] In some embodiments of this application, at least any two of the conformal deposition, selective etching, and selective deposition can employ at least partially the same homologous material system. The use of homologous materials allows for seamless switching between etching and deposition within the same cavity, ensuring the complete preservation of surface active sites and guaranteeing the uniformity and adhesion of subsequent selective deposition. For example, in selective etching, gaseous MoCl5 is selected as the etching gas, and in selective deposition, gaseous MoCl5 is selected as the metal precursor. In this scenario, the etching gas and the metal precursor employ the same homologous material system.

[0071] In the embodiments of this application, a homologous material system refers to an etchant used in the selective etching step and a metal precursor used in the selective deposition step that employ the same metal element or core chemical framework. Specifically, a homologous material system may refer to a material combination strategy that utilizes compounds of the same metal (such as molybdenum chlorides) as both etching reactants and growth raw materials. For example, molybdenum pentachloride (MoCl5) is used as an etching gas to remove the sidewall seed layer in the selective etching step, while a molybdenum-containing compound (such as MoCl5 or MoO2Cl2) is used as a metal precursor for the subsequent deposition of the filler layer in the selective deposition step.

[0072] The homogeneity in the homologous material system lies in eliminating the incompatibility between different chemical substances, thereby achieving extreme simplification of the process environment and precise control of the interface. Regarding avoiding chamber contamination, since the etching residue and the deposition precursor have the same chemical properties, they will not undergo uncontrollable gas-phase side reactions to generate particulate matter. Furthermore, the residue can be treated as additional raw material and discharged, achieving an atomically clean reaction environment. This facilitates seamless switching between etching and deposition within the same chamber without complex cleaning steps. Regarding avoiding interface reactions, the homologous materials maintain the consistency of surface chemically active sites. The chemical bonding environment on the surface of the bottom seed layer can be directly transformed into nucleation sites for deposition after etching, avoiding interface barriers or dead layers caused by abrupt changes in chemical properties. This is beneficial for maintaining reliable electrical connections and adhesion between the filler layer and the conductive liner layer.

[0073] In some embodiments of this application, at least any two of the conformal deposition, selective etching, and selective deposition may share the same reaction chamber, and at least any two may use at least partially the same homologous material system.

[0074] Although the process described above includes multiple operations that appear in a specific order, it should be clearly understood that these processes may include more or fewer operations, which may be executed sequentially or in parallel.

[0075] This application also provides a semiconductor structure obtained based on the above method. (See reference...) Figure 7As shown, the semiconductor structure may include a substrate 10 with a groove structure, the groove structure including a bottom and sidewalls, a conductive liner layer 12 is disposed on the bottom of the groove structure, and the rest of the groove structure is filled with a filling layer 13, the filling layer 13 being in direct contact with the sidewalls of the groove structure (i.e. the sidewalls of the groove structure have no conductive liner layer 12).

[0076] In some embodiments of the semiconductor structure of this application, the aspect ratio of the groove structure is greater than 5:1.

[0077] In some embodiments of the semiconductor structure of this application, the conductive liner layer is a metal seed layer.

[0078] It should also be understood that, in the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0079] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the product embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0080] In the description of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this application, as well as the features of different embodiments or examples.

[0081] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A bottom-up, selective filling method, characterized in that, include: Provide a substrate with a recessed structure; A conductive liner layer is formed at the bottom of the recessed structure; A filler material is selectively deposited from bottom to top on the conductive liner layer to form a filler layer that fills the recessed structure.

2. The method of claim 1, wherein, The resistivity of the filler material is lower than that of the conductive lining layer.

3. The method as described in claim 1, characterized in that, The formation of a conductive liner layer at the bottom of the recessed structure includes: A conductive liner layer is conformally deposited on the surface of the recessed structure; The conductive liner layer on the top and sidewalls of the recessed structure is selectively etched to retain the conductive liner layer at the bottom of the recessed structure.

4. The method as described in claim 3, characterized in that, At least two of the conformal deposition, the selective etching, and the selective deposition share the same reaction chamber and / or employ at least partially the same homologous material system.

5. The method as described in claim 3, characterized in that, The selective etching of the conductive liner layer on the top and sidewalls of the recessed structure includes: Etching gas is pulsed into the recessed structure to cause a chemical reaction between the surface of the conductive liner layer and the etching gas, generating volatile products at a rate decreasing from top to bottom. The volatile products and residual etching agent after the reaction were purged with purge gas; Repeat the etching steps described above to gradually remove the conductive liner layer on the top and sidewalls of the recessed structure.

6. The method as described in claim 5, characterized in that, The step of pulsedly introducing etching gas into the recessed structure includes: The etching gas is introduced into the recessed structure based on a set introduction time, so that the concentration of the etching gas in the recessed structure decreases from top to bottom, and the introduction time is 0.1 to 5 seconds.

7. The method as described in claim 5, characterized in that, Before pulsed introduction of etching gas into the recessed structure, the method further includes: Using inert gas as a carrier gas, a predetermined amount of etching gas is carried from the source gas source to the buffer gas source, which forms the pulsed supply source.

8. The method as described in claim 1, characterized in that, The selective deposition of filler material from bottom to top on the conductive liner layer includes: A metal precursor is introduced into the recessed structure, so that the metal precursor is adsorbed onto the surface of the conductive liner layer. The metal precursors that were not adsorbed onto the surface of the conductive liner layer within the recessed structure were purged with purge gas. A reducing agent is introduced into the recessed structure to cause the reducing agent to chemically react with the metal precursor adsorbed on the surface of the conductive liner layer, and to form a filling layer on the surface of the conductive liner layer. Use purge gas to purge the remaining reducing agent and reaction byproducts after the reaction; Repeat the above deposition steps until a filling layer is formed from bottom to top, filling the depression structure.

9. The method as described in claim 8, characterized in that, During the selective deposition of filler material from bottom to top on the conductive liner layer, the temperature of the cavity containing the recessed structure is 300℃~600℃.

10. A semiconductor structure obtained by the method according to any one of claims 1 to 9, characterized in that, The semiconductor structure includes a substrate with a groove structure, the groove structure including a bottom and sidewalls, the bottom of the groove structure being covered with a conductive liner layer, and the remainder of the groove structure being filled with a filler layer.

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