Gap feature filling method

Abstract

The invention discloses a gap feature filling method. The filling method comprises the following steps: at a first temperature, introducing a halogen group-containing surface reaction inhibitor, so that the halogen group-containing surface reaction inhibitor is reversibly adsorbed on active sites of gap characteristics to form a passivation layer; adjusting a deposition region of the introduced first precursor and / or second precursor in the gap feature via the barrier of the passivation layer; and in response to the deposition film morphology in the gap feature reaching the preset morphology, raising the temperature to a second temperature to remove the passivation layer. By executing the steps, the deposition reaction activity of a specific region in the gap feature on the surface of the substrate can be selectively and reversibly inhibited, the film forming defect of diffusion gradient can be fundamentally compensated, and a film layer with uniform height and excellent shape retention can be deposited in a high aspect ratio structure; and in the process of recovering the deposition reaction activity of the specific area, the operation is convenient, and damage or cross contamination cannot be caused to a substrate interface.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor manufacturing, and more specifically to a method for filling gap features. Background Technology

[0002] With the continuous miniaturization of semiconductor device feature sizes and the widespread application of three-dimensional structures (such as the memory holes in 3D NAND flash memory, deep trench capacitors in DRAM, and FinFETs in advanced logic devices), high aspect ratio structures have become a common feature in modern chip manufacturing. The ever-increasing aspect ratio of these structures poses an extreme challenge to depositing uniform and conformally consistent functional thin films within them. Compared to PVD and CVD methods, atomic layer deposition (ALD) technology, with its inherent self-limiting surface reaction characteristics, can achieve atomic-scale film thickness control and excellent step coverage, and is widely used to deposit key materials such as titanium nitride (TiN), which is commonly used as electrodes and diffusion barrier layers.

[0003] In the traditional TiN ALD process, TiCl4 and NH3 are alternately pulsed in cycles, followed by purging with an inert gas after each pulse to remove unreacted precursors and gaseous byproducts, thereby generating TiN films based on self-limiting surface reactions. However, when dealing with structures with extremely high aspect ratios (e.g., greater than 50:1), this traditional TiN ALD process faces severe challenges, its inherent physicochemical limitations are exposed, and film uniformity deteriorates significantly. First, precursor diffusion is gradient-limited. Precursor molecules mainly rely on diffusion to enter deep pores or narrow slit structures. When precursor TiCl4 or NH3 molecules diffuse from the structural opening to the bottom, they are preferentially adsorbed and consumed by the opening and the upper sidewalls. Due to the limitation of molecular diffusion rate, the precursor concentration reaching the bottom is significantly reduced, forming a top-down film thickness gradient, i.e., the "bottom thin" problem. Second, selective control cannot be achieved. The traditional dual-precursor ALD process performs indiscriminate diffusion-adsorption and reaction on all exposed surfaces, thus failing to actively compensate for the concentration unevenness caused by physical diffusion. Furthermore, process optimization is prone to bottlenecks. To improve the uniformity of deposited films, existing technologies typically employ passive optimization methods, such as extending the TiCl4 pulse and purge times. However, this not only results in significant precursor waste but also directly leads to a substantial increase in the cycle time per wafer, severely sacrificing production efficiency (i.e., throughput). Moreover, for structures with continuously increasing aspect ratios, this method of simply extending diffusion time has reached its limit. Developing new precursors faces challenges related to cost, stability, and changes in film performance.

[0004] To address this, existing technologies have proposed several selective deposition methods. In some methods, a passivation layer at least partially inhibits the growth of the filling film in a portion of the substrate surface. However, this approach only includes the passivation layer formation stage and does not address the removal of this inhibitor, resulting in incomplete filling of the final structure with a specific aspect ratio, thus affecting device performance. Furthermore, while other deposition methods involve removing the passivation layer, they employ destructive methods such as etching. This process can easily damage the deposited film and / or the substrate surface, also leading to functional impairment of the final device.

[0005] To address the aforementioned problems in the prior art, there is an urgent need in the art for an improved gap feature filling technique that can selectively and reversibly suppress the deposition reactivity in specific regions of the gap features on the substrate surface, fundamentally compensating for film-forming defects caused by diffusion gradients. This technique can not only deposit highly uniform and shape-preserving films within high aspect ratio structures, but also restore the deposition reactivity in the aforementioned specific regions in a convenient manner without causing damage or cross-contamination to the substrate interface. Summary of the Invention

[0006] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed descriptions that follow.

[0007] To overcome the aforementioned deficiencies in the prior art, the present invention provides a method for filling gap features that can selectively and reversibly suppress the deposition reactivity in specific regions of gap features on the substrate surface, fundamentally compensating for film-forming defects caused by diffusion gradients. This method not only enables the deposition of highly uniform and conformally excellent films within high aspect ratio structures, but also provides convenient operation and avoids damage or cross-contamination to the substrate interface during the process of restoring the deposition reactivity in the aforementioned specific regions.

[0008] Specifically, the method for filling the gap feature described above is provided according to a first aspect of the present invention. The gap feature is located on the surface of a substrate. The filling method includes the following steps: at a first temperature, introducing a surface reaction inhibitor containing a halogen group to reversibly adsorb onto the active sites of the gap feature to form a passivation layer; adjusting the deposition area of ​​the introduced first precursor and / or second precursor within the gap feature via the barrier of the passivation layer; and in response to the deposition film morphology within the gap feature reaching a preset morphology, raising the temperature to a second temperature to remove the passivation layer. Attached Figure Description

[0009] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0010] Figure 1 A flowchart of a method for filling a gap feature according to some embodiments of the present invention is shown.

[0011] Figure 2 A schematic diagram of the ALD deposition process provided according to some embodiments of the present invention is shown.

[0012] Figure 3 A schematic diagram of the molecular structure of a surface reaction inhibitor provided according to some embodiments of the present invention is shown.

[0013] Figure label: Steps S110~S130; 200 Gap Characteristics; 210 Opening area; 211 Top surface; 212 Upper sidewall; 220 Deposited film. Detailed Implementation

[0014] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a thorough understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description.

[0015] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0016] Furthermore, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," and "vertical" used in the following description should be understood as the orientations shown in the relevant paragraphs and accompanying drawings. These relative terms are for illustrative purposes only and do not imply that the described apparatus must be manufactured or operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0017] It is understood that although terms such as "first," "second," and "third" may be used herein to describe various components, regions, layers, and / or parts, these components, regions, layers, and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers, and / or parts. Therefore, the first components, regions, layers, and / or parts discussed below may be referred to as second components, regions, layers, and / or parts without departing from some embodiments of the present invention.

[0018] As mentioned above, in some deposition methods, a passivation layer at least partially inhibits the growth of the filling film in a portion of the substrate surface. However, this approach only includes the passivation layer formation stage and does not address the removal of this inhibitor, resulting in the final structure with an aspect ratio not being fully filled, thus affecting device performance. Furthermore, in other deposition methods, although the removal of the passivation layer is involved, it employs destructive methods such as etching. This process can easily damage the deposited film and / or the substrate surface, also leading to impaired device functionality.

[0019] To address the aforementioned problems in the prior art, this invention provides a method for filling gap features that can selectively and reversibly suppress the deposition reactivity in specific regions of gap features on the substrate surface, fundamentally compensating for film-forming defects caused by diffusion gradients. This method not only enables the deposition of highly uniform and conformally excellent films within high aspect ratio structures, but also provides convenient operation and avoids damage or cross-contamination to the substrate interface during the process of restoring the deposition reactivity in the aforementioned specific regions.

[0020] Please refer to Figure 1 . Figure 1 A flowchart of a method for filling a gap feature according to some embodiments of the present invention is shown.

[0021] like Figure 1 As shown, in some embodiments of the present invention, the method for filling the gap features may include steps S110 to S130. This filling method completes the ALD deposition process, thereby improving the filling capacity and uniformity of the deposited film within the gap features.

[0022] Specifically, step S110 involves introducing a surface reaction inhibitor containing halogen groups at a first temperature, so that it can be reversibly adsorbed onto the active sites of the interstitial feature to form a passivation layer. Step S120 involves adjusting the deposition area of ​​the introduced first precursor and / or second precursor within the interstitial feature via the barrier of the passivation layer.

[0023] Furthermore, please combine Figure 2 A shared understanding. Figure 2 A schematic diagram of the ALD deposition process provided according to some embodiments of the present invention is shown.

[0024] like Figure 2 As shown, in some embodiments, the gap feature 200 can be distributed on the substrate surface. Active sites include an opening region 210 located on the upper part of the gap feature 200. Because the opening region 210 of the gap feature 200 has an edge / corner morphology, the coordination environment of its surface atoms is unsaturated (1-2 fewer adjacent atoms than in the planar region), resulting in a significantly higher surface energy than the planar region at the bottom of the gap feature 200. From a thermodynamic perspective, the high surface energy region will spontaneously adsorb active substances in the environment (such as water molecules and oxygen molecules in the air), forming a large number of active functional groups such as -OH. In contrast, the planar region at the bottom of the gap feature 200 has saturated atomic coordination and low surface energy, making it difficult to form active sites. Furthermore, the opening region 210 can at least include the top surface 211 of the gap feature 200 and / or the upper sidewall 212 inside the gap feature 200.

[0025] In this invention, surface reaction inhibitors containing halogen groups may include one or more of hydrogen halides, halogenated hydrocarbons, and halogenated silanes. These small molecule compounds with halogen groups are gaseous at room temperature or have high saturated vapor pressures, and possess good thermal stability and moderate reactivity.

[0026] Specifically, combined Figure 3 It is generally understood that in the general formula HX of hydrogen halides, X is selected from chlorine, bromine, or iodine atoms. That is, hydrogen halides can be selected from hydrogen chloride (HCl), hydrogen bromide (HBr), or hydrogen iodide (HI). Halogenated hydrocarbons can include chloromethane (CH3Cl), dichloromethane (CH2Cl2), chloroform (CHCl3), or their brominated or iodinated derivatives. Furthermore, the general formula of halogenated hydrocarbons can be RX, where X is selected from chlorine, bromine, or iodine atoms, and R can be selected from methyl, ethyl, n-propyl, isopropyl, or tert-butyl. Halogenated silanes can include those with the general formula H... n SiX 4-n Hydrohalosilanes, wherein X is selected from chlorine, bromine, or iodine atoms, and n is an integer from 1 to 3. Halosilanes may also include trimethylhalosilanes with the general formula (CH3)3-SiX, wherein X is selected from chlorine, bromine, or iodine atoms.

[0027] In some embodiments, when the deposition requirement is to deposit a thin film only in a portion of the gap feature 200, while leaving other areas undeposited, a surface reaction inhibitor containing halogen groups can be directly introduced into the original gap feature 200 before the first precursor pulse is introduced into the process chamber, i.e., before the start of the entire ALD cycle. This allows the inhibitor to reversibly adsorb onto the target deposition area. A passivation layer is then formed over the non-target deposition area via the surface reaction inhibitor. The process chamber can be a vertical furnace tube type or a monolithic process chamber.

[0028] For example, the substrate can include various materials such as SiO2, Si3N4, Co, W, and Ti. If the goal is to deposit TiN only on a specific target material (such as a Ti seed layer) to achieve regioselective atomic layer deposition (AS-ALD), surface reaction inhibitors can preferentially adsorb onto the surface of non-target materials (such as oxides and nitrides), forming a stable passivation layer through the binding of halogen groups with surface hydroxyl groups or dangling bonds. Surface reaction inhibitors have weaker adsorption on the target material surface or can be replaced by subsequent Ti precursors. Therefore, during the first Ti precursor pulse, the Ti precursor only undergoes effective adsorption and nucleation in the uninhibited region (i.e., the region not covered by the passivation layer).

[0029] Furthermore, in some optional embodiments, the adsorption region of the surface reaction inhibitor can be precisely controlled by adjusting the introduction angle, minimizing its diffusion in non-target deposition areas. In this embodiment, initial nucleation selectivity is established via the surface reaction inhibitor before the first precursor pulse is introduced, thereby achieving zero nucleation in non-target deposition areas and avoiding parasitic deposition during subsequent cycles. Moreover, since the adsorption of the surface reaction inhibitor is probabilistic, temporary selectivity can also be achieved, facilitating subsequent multi-step integration.

[0030] In other embodiments, when the deposition requirement is to suppress film thickening in the opening region 210, preventing premature sealing due to incomplete filling within the gap feature 200, as in this case... Figure 2As shown, during the execution of steps S110 and S120, after several pulse introductions of the first precursor, first precursor purging, pulse introduction of the second precursor, and second precursor purging, it can be determined whether the opening gap of the gap feature 200 covering the deposition film 220 is less than the gap threshold. When the opening gap is less than the gap threshold, a surface reaction inhibitor can be introduced to reversibly adsorb onto the opening region 210 to form a passivation layer. In this embodiment, the precursor adsorption probability in the bottom region within the gap feature 200 can be enhanced, thereby achieving self-limiting bottom-preferred deposition, reducing the generation of voids during the filling process, and improving the filling quality.

[0031] For example, after several standard ALD cycles, a TiN film of a certain thickness has formed on the top surface 211 and / or the upper sidewall 212 inside the gap feature 200. At this point, the growth rate of the TiN film in the opening region 210 is significantly faster than that at the bottom, showing a tendency to close. To address this, surface reaction inhibitors can selectively adsorb onto the exposed TiN surface, such as the top surface 211 and / or the upper sidewall 212 inside the gap feature 200. By coordinating halogen groups with surface Ti atoms, they temporarily passivate the reactive sites, reducing the Ti precursor's adsorption capacity in the next cycle. Therefore, during the next Ti precursor pulse, because the upper active sites are occupied by the passivation layer, the Ti precursor is forced to diffuse deeper into the bottom of the gap feature 200 to adsorb in its bottom region. Similarly, when the next N precursor pulse is applied, the N precursor will automatically diffuse deeper into the bottom of the interstitial feature 200 because the upper active sites are covered by the passivation layer, so as to react with the Ti precursor deposition in the bottom region.

[0032] Furthermore, in some alternative embodiments, when the deposition requirement necessitates precise control of the elemental chemical ratio of the deposition film 220 in a specific region. To this end, during the execution of steps S110 and S120, after completing several purging steps of the first and second precursors, the stoichiometric ratio (i.e., first element: second element) of the first element and the second element in the deposition film 220 within the interstitial feature 200 can be obtained. The first element is provided via the first precursor, and the second element is provided via the second precursor. It is then determined whether the detected stoichiometric ratio of the target region is within the target ratio range.

[0033] Specifically, if the stoichiometry is less than the lower limit of the target ratio range, it indicates that the content of the first element is too low. To address this, in the next ALD cycle, the first precursor is first pulsed in to increase the content of the first element in the target region. Then, after the first precursor purge step, a surface reaction inhibitor can be introduced to reversibly adsorb onto the target region and form a passivation layer. At this point, during the subsequent pulsed introduction step of the second precursor, the second precursor will be blocked by the passivation layer, reducing the probability of deposition on the target region. Conversely, if the stoichiometry is greater than the upper limit of the target ratio range, it indicates that the content of the first element is too high. To address this, before the next ALD cycle begins, i.e., after the previous second precursor purge step, a surface reaction inhibitor is introduced to pre-adsorb reversibly onto the target region and form a passivation layer. At this point, during the next pulsed introduction step of the first precursor, the first precursor will be blocked by the passivation layer, reducing the probability of deposition on the target region. In this embodiment, the spatial selectivity of the chemical reaction pathway of the deposited film 220 can be precisely controlled, which helps to optimize the film purity and fine-tune the interface properties.

[0034] For example, when depositing TiN films using Ti precursors, it is necessary to precisely control the position of Ti–N bonds or avoid undesirable side reactions such as over-nitriding in certain areas. In this case, the Ti precursor has already adsorbed across the entire surface of the substrate, especially the interstitial feature 200, but the N precursor has not yet been introduced to react with it. Introducing a surface reaction inhibitor can selectively passivate the adsorbed Ti species in specific target regions, thereby preventing the N precursor from approaching the Ti centers in those target regions.

[0035] Alternatively, a surface reaction inhibitor can be introduced separately after the first or second precursor to achieve spatial selectivity of the chemical reaction pathway of the deposited film, allowing for precise control. See the second embodiment provided later for details, which will not be repeated here.

[0036] In the above-described embodiments of the present invention, small molecule compounds containing halogen groups are pulsed into the process chamber as surface reaction inhibitors. These surface reaction inhibitors can reversibly and preferentially adsorb onto the openings and upper regions of the high aspect ratio gap feature 200, temporarily passivating the active sites in these regions. This helps guide the subsequent first and / or second precursors to diffuse more effectively to the bottom of the gap feature 200, preferentially performing bottom deposition. Through this active spatially selective growth control, the problems of poor film uniformity and incomplete filling caused by the natural diffusion gradient limitation of the precursor in conventional processes are compensated. The film can grow upwards from the bottom of the gap feature 200, thereby significantly improving the uniformity and filling capacity of the film within the high aspect ratio structure.

[0037] Please continue to return Figure 1 Then step S130 can be executed, in response to the deposited film morphology within the gap feature reaching the preset morphology, the temperature is raised to the second temperature to remove the passivation layer.

[0038] Specifically, in some embodiments, during the filling process of the gap feature 200 using the ALD deposition process, it can be determined whether the deposited film layer in the bottom region of the gap feature 200 has reached a preset depth. For example, the preset depth can be 2 / 3 of the total depth of the gap feature 200. When the deposited film layer reaches this preset depth, the temperature can be raised to a second temperature to expose the active sites originally covered by the passivation layer. Then, the first precursor and / or the second precursor are continued to be introduced to perform omnidirectional deposition in all regions of the gap feature 200, thus completely filling the gap feature 200. In other embodiments, the preset morphology may also include a preset deposition thickness of the sidewalls, or a preset deposition thickness corresponding to a specific region, etc. Therefore, the preset depth mentioned in the above embodiments should not unduly limit the scope of protection of the present invention.

[0039] Optionally, for the same surface reaction inhibitor, the temperature difference between the second temperature and the first temperature is at least 50°C. That is, the second temperature is at least 50°C higher than the first temperature. The essential requirement for the reversible adsorption of surface reaction inhibitors is that low temperatures are needed during adsorption to reduce molecular thermal kinetic energy, thereby promoting the formation of weak interactions (such as hydrogen bonds and van der Waals forces) between the inhibitor and the interstitial surface. During desorption, higher temperatures are required to provide energy to break these weak interactions. Further, the temperature difference between the second and second temperatures is preferably between 50°C and 100°C. A small temperature difference can easily lead to unstable inhibitor adsorption, while a large temperature difference increases the difficulty of temperature control in the process. For example, for the surface reaction inhibitor HCl, its adsorption temperature is room temperature (e.g., 25°C), and its desorption temperature can be between 80°C and 120°C. The difference between the adsorption and desorption temperatures meets the requirements, so adsorption can be achieved at room temperature, and desorption can be completed at 120°C, thus achieving precise control over the adsorption and desorption states of the surface reaction inhibitor.

[0040] Furthermore, in some embodiments, the second temperature is preferably within the deposition process temperature window of the deposited film. Here, the "deposition process temperature window" is defined as the temperature range within which the precursor can achieve self-limited adsorption and reaction without significant thermal decomposition. In this embodiment, when the second temperature corresponding to the inhibitor desorption temperature is between the upper and lower limits of the deposition process temperature of the deposited film, no additional temperature control is required, and desorption can be directly completed using the ALD process temperature, resulting in the simplest process steps. For example, in the ALD process of titanium nitride, the Ti precursor source can be titanium tetrachloride. The process temperature window for the ALD process of titanium nitride is 150°C. 350℃. The desorption temperature of halosilane inhibitors is 150℃. 250℃, which matches the process temperature window. Since the upper limit of the desorption temperature of the halosilane inhibitor is lower than the thermal decomposition temperature of titanium tetrachloride (360℃), it can be ensured that the precursor can continue to undergo a self-limiting reaction after the inhibitor is desorbed.

[0041] In some alternative embodiments, the second temperature may also be below the lower limit of the deposition process temperature window. In this embodiment, since the second temperature corresponding to the inhibitor desorption temperature is below the lower limit of the deposition process temperature, the heating process can be combined with the preheating step in the ALD process, thereby shortening the process time and improving process efficiency. For example, in the ALD process of alumina, the deposition process temperature window is 120°C. 250℃. HCl was selected as the surface reaction inhibitor, and its desorption temperature is 80℃. 120℃. During the process of preheating the substrate from 80℃ to 120℃ (i.e., the lower limit of the deposition process temperature), HCl can be completely desorbed, and then TMA / H2O can be directly introduced as the first precursor for deposition.

[0042] Furthermore, the first precursor may include a Ti precursor. Specifically, Ti-containing precursors may include, but are not limited to, titanium tetrachloride (TiCl4), tetrakis(dimethylamino)titanium (TDMAT), tetrakis(diethylamino)titanium (TDEAT), or tetrakis(ethylmethylamido)titanium (TEMATi). The second precursor may include a nitrogen-containing reaction gas. Specifically, nitrogen-containing precursors may include, but are not limited to, ammonia (NH3) and hydrazine (N2H4).

[0043] According to the embodiments provided by the present invention, in the method for filling gap features including steps S110 to S130, surface reaction inhibitor molecules can be reversibly adsorbed onto a portion of the gap feature 200 or onto the surface of the already grown TiN deposited film. The surface reaction inhibitor molecules preferentially adsorb onto the substrate surface and the opening region 210 of the three-dimensional gap feature 200, or a predetermined target region, forming a temporary passivation layer. This temporarily blocks the adsorption and surface reaction of subsequent titanium- or nitrogen-containing precursor molecules at this site, thereby inhibiting subsequent film growth (deposition) in this region. In subsequent cyclic pulse steps such as NH3 or TiCl4, since the active sites in these regions have been selectively occupied by the surface reaction inhibitor, NH3 or TiCl4 molecules can be forced to diffuse more effectively into the depth region of the three-dimensional structure and form a film at the bottom region of the gap feature 200. This achieves an optimized filling mode of film growth from bottom to top, effectively improving uniformity.

[0044] Furthermore, as the deposition process proceeds, the process temperature can be adjusted to induce the thermodynamically driven desorption of inhibitor molecules adsorbed in the opening region 210 or specific target regions. This exposes the previously temporarily passivated active sites, allowing them to participate in subsequent thin film deposition reactions and ultimately achieving uniform thin film coverage throughout the gap features 200 of the entire three-dimensional structure. In this invention, the aforementioned thermal desorption method is a weak chemical process that only disrupts the adsorption bonds between the inhibitor and the surface (such as Si–Cl, Ti–Cl, Si–F), without attacking the underlying thin film or substrate. In contrast, traditional etching methods for removing passivation layers easily corrode the deposited thin film (e.g., TiN films are easily etched by chloride ions) or damage sensitive materials (e.g., high-k dielectrics, ultrathin gates, low-k dielectrics), resulting in interface defects. Moreover, thermal desorption exhibits high selectivity and self-limitation. The desorption process only occurs in the suppressed region and does not affect other regions. Conversely, etching methods struggle to achieve region selectivity. Once an etchant is introduced, all exposed surfaces may be bombarded unless complex masking techniques are used. Thermal desorption only requires heating, eliminating the need for additional auxiliary desorption tools, making it simple and easy to implement. Furthermore, the thermal desorption method in this invention offers good process compatibility and convenient integration. Since thermal desorption only requires adjusting the temperature of the process chamber, it can be completed within the same ALD chamber without the need to transfer or introduce new gases. In contrast, etching methods typically require additional etching chambers, complex gas switching, and cleaning steps, leading to increased equipment costs and operational complexity, and also increasing the risk of cross-contamination (e.g., residual Cl-based etchants can affect the purity of subsequent ALD films).

[0045] Furthermore, since the surface reaction inhibitors provided by this invention are gaseous or easily volatile at room temperature and have good thermal stability, they can be directly integrated into existing ALD equipment (such as TiCl4 / NH3 ALD equipment). Therefore, this invention has low implementation costs, improves performance while also ensuring production efficiency, and has excellent process compatibility.

[0046] Next, please refer to the process parameters in the two specific embodiments to further understand the above-mentioned gap feature filling method.

[0047] In the first embodiment, hydrogen chloride is used as a surface reaction inhibitor. TiN thin films are deposited on a silicon substrate with a gap feature 200 having an aspect ratio of 60:1 in a hot-wall type ALD process chamber (multi-tube or single-tube type). The deposition temperature is controlled at 450°C. The operating pressure is 1 Torr. High-purity nitrogen (N2) can be used as the purge gas to remove deposition byproducts and improve film quality. Alternatively, other inert gases (such as argon) can be used as the purge gas. However, nitrogen is less expensive and more suitable for large-scale application compared to other inert gases. The titanium precursor can be TiCl4, and the nitrogen precursor can be NH3. Hydrogen chloride (HCl) can be used as the surface reaction inhibitor. During the gap feature filling process using the ALD process provided by this invention, the following sequence and parameters can be used in a cyclical manner: S1, perform a TiCl4 pulse with a flow rate of 1 slm and a pulse duration of 10 seconds. S2, perform an N2 purge for 20 seconds. After purging the first precursor, step S3 is executed, introducing a pulse of HCl into the process chamber at a flow rate of 2 slm for 5 seconds to form a temporary passivation layer in a portion of the TiCl4 film via HCl. Step S4 involves N2 purging for 20 seconds. Subsequently, the second precursor is introduced, and step S5 is executed, introducing a pulse of NH3 into the process chamber at a flow rate of 5 slm for 10 seconds. Step S6 involves another N2 purging for 20 seconds. In this embodiment, each cycle of the above six steps allows for the precise deposition of a TiN film with a thickness of 0.5 Å. The target thickness can be achieved by controlling the number of cycles. Repeating this cycle yields a TiN film with excellent uniformity.

[0048] In the second embodiment, tert-butane chloride (Cl-C(CH3)3) can be used instead of HCl as a surface reaction inhibitor. The main process parameters remain unchanged, but the inhibitor is replaced with tert-butane chloride vapor. Similarly, during the ALD process for filling the gap features, the following sequence and parameters can be used in a cyclical manner: S1, perform a TiCl4 pulse with a flow rate of 1 slm and a pulse duration of 10 seconds. S2, perform an N2 purging for 20 seconds. Then, introduce the second precursor and execute S3, introducing an NH3 pulse into the process chamber with a flow rate of 5 slm and a pulse duration of 10 seconds. S4, perform an N2 purging for 20 seconds. After completing the second precursor purging, S5 can be executed, introducing a Cl-C(CH3)3 pulse into the process chamber with a flow rate of 1 slm and a pulse duration of 3 seconds to form a temporary passivation layer in a portion of the TiCl4 film via Cl-C(CH3)3. Those skilled in the art will understand that, due to the different molecular sizes and reactivity of surface reaction inhibitors containing halogen groups, their corresponding process parameters can be appropriately optimized and adjusted. Afterwards, step S6 is executed, followed by N2 purging for 30 seconds. In this embodiment, after 200 cycles, a TiN film with a thickness of approximately 10 nm can be deposited within the interstitial features. Using organochlorinated hydrocarbon surface reaction inhibitors can also achieve excellent interstitial feature filling effects.

[0049] Furthermore, transmission electron microscopy (TEM) characterization revealed that, in the second embodiment described above, the TiN film deposited using the filling method of the present invention exhibited excellent uniformity within the 60:1 deep-hole gap feature, with no void formation and a step coverage of nearly 97%. In contrast, in the comparative experiment using the conventional ALD process for gap feature filling, the film showed a significant top-to-bottom thickness gradient, and voids appeared during filling at high aspect ratios.

[0050] This invention improves the mature TiN ALD process by filling the gap features described above, achieving selective passivation of the growth surface. This allows for selective control of the film growth rate distribution at different spatial locations within the structure, thereby significantly enhancing the filling capacity and uniformity of TiN films in high aspect ratio structures (from the opening to the bottom and sidewalls).

[0051] Furthermore, the method for filling the gap features described above in this invention can not only be applied to the preparation of titanium nitride (TiN) thin films, i.e., filling the gap features 200 with TiN thin films, but can also be extended to various binary or multi-component compound thin film systems composed of metal precursors and non-metallic reactive gases.

[0052] Specifically, in some embodiments, the first precursor, in addition to the Ti precursor listed above, may also be selected from organometallic compounds or halides containing Ta, W, Nb, Mo, V, Al, Hf, Zr, Si, or Zn. Furthermore, the second precursor, in addition to the N-containing reaction gases listed above, may also be selected from reaction gases containing O, C, S, or Se.

[0053] In summary, this invention provides a method for filling gap features that goes beyond simply adjusting the temperature, time, and flow rate of the precursor. Instead, it introduces a novel chemical substance that can selectively and reversibly suppress the deposition reactivity in specific regions of the gap features on the substrate surface. This fundamentally compensates for film-forming defects caused by diffusion gradients. Not only can it deposit highly uniform and conformally excellent films within high aspect ratio structures, but it is also convenient to operate and does not damage or cross-contaminate the substrate interface during the process of restoring the deposition reactivity in the aforementioned specific regions.

[0054] 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.

[0055] The prior description of this disclosure is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for filling a gap feature, wherein the gap feature is located on the surface of a substrate, characterized in that, The filling method includes the following steps: At a first temperature, a surface reaction inhibitor containing halogen groups is introduced to reversibly adsorb onto the active sites of the interstitial features to form a passivation layer; The deposition area of ​​the first precursor and / or the second precursor within the gap feature is adjusted via the barrier of the passivation layer; and In response to the deposited film morphology within the gap feature reaching a preset morphology, the temperature is raised to a second temperature to remove the passivation layer.

2. The filling method as described in claim 1, characterized in that, The active site includes an opening region located on the upper part of the gap feature, wherein the opening region includes at least the top surface of the gap feature and / or the upper sidewall inside the gap feature.

3. The filling method as described in claim 2, characterized in that, The step of introducing a surface reaction inhibitor containing a halogen group includes: In response to completing a number of purging steps of the first precursor and the second precursor, it is determined whether the opening gap of the gap feature covering the deposited film is less than a gap threshold; and In response to the opening gap being less than the gap threshold, the surface reaction inhibitor is introduced so that it is reversibly adsorbed onto the opening region to form the passivation layer.

4. The filling method as described in claim 3, characterized in that, The response, after completing a plurality of purging steps of the first precursor and the second precursor, further includes: Obtain the stoichiometric ratio of a first element and a second element in the deposited film within the target region of the gap feature, wherein the first element is provided via the first precursor and the second element is provided via the second precursor; Determine whether the measurement ratio is within the target ratio range; In response to the dosage ratio being less than the lower limit of the target ratio range, after completing the purge step of the first precursor, the surface reaction inhibitor is introduced to reversibly adsorb onto the target region to form the passivation layer; and In response to the metering ratio being greater than the upper limit of the target ratio range, after the purging step of the second precursor is completed, the surface reaction inhibitor is introduced so that it is reversibly adsorbed onto the target region to form the passivation layer.

5. The filling method as described in claim 1, characterized in that, The step of heating to a second temperature in response to the deposited film morphology within the gap feature reaching a preset morphology to remove the passivation layer includes: Determine whether the deposited film layer in the bottom region within the gap feature has reached a preset depth; In response to the deposited film reaching the preset depth, the temperature is raised to the second temperature to expose the active sites previously covered by the passivation layer, wherein the temperature difference between the second temperature and the first temperature is at least 50°C; and Continue to introduce the first precursor and / or the second precursor to completely fill the gap feature.

6. The filling method as described in claim 5, characterized in that, The second temperature is within the deposition process temperature window of the deposited film, or below the lower limit of the deposition process temperature window.

7. The filling method as described in claim 1, characterized in that, The surface reaction inhibitors include one or more of hydrogen halides, halogenated hydrocarbons, and halogenated silanes.

8. The filling method as described in claim 7, characterized in that, In the general formula HX of the hydrogen halide, X is a chlorine, bromine, or iodine atom. The haloalkanes include chloromethane, dichloromethane, chloroform, or their brominated or iodinated derivatives, as well as haloalkanes of the general formula RX, wherein X is a chlorine, bromine, or iodine atom, and R is methyl, ethyl, n-propyl, isopropyl, or tert-butyl. The halosilane includes those with the general formula H n SiX 4-n Hydrohalosilanes, wherein X is a chlorine, bromine or iodine atom and n is an integer from 1 to 3, and trimethylhalosilanes with the general formula (CH3)3-SiX, wherein X is a chlorine, bromine or iodine atom.

9. The filling method as described in claim 1, characterized in that, The first precursor is selected from organometallic compounds or halides containing Ti, Ta, W, Nb, Mo, V, Al, Hf, Zr, Si or Zn.

10. The filling method as described in claim 1, characterized in that, The second precursor is selected from a reaction gas containing N, O, C, S or Se.

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