Aluminum-doped oxide film and preparation method thereof

Abstract

The invention discloses an aluminum-doped oxide thin film and a preparation method thereof, relates to the technical field of preparation of nano thin film materials, and aims to solve the problems that in the prior art, a high-dielectric-constant material is easy to crystallize after high-temperature annealing, so that leakage current is increased, interface characteristics are degraded, and structural damage is caused by a plasma process. Comprising the following steps: carrying out alternate pulse conveying on a metal precursor at a preset process temperature; the metal precursor comprises a first metal precursor and a second metal precursor; the first metal precursor is a hafnium-containing compound, and the second metal precursor is an aluminum-containing compound; carrying out oxidation reaction on the metal precursor based on the oxygen-containing precursor, and sequentially generating a hafnium oxide sub-layer and an aluminum oxide sub-layer on the surface of the heating substrate; after hafnium oxide sublayer growth circulation is executed, aluminum oxide sublayer growth circulation is inserted once, and a hypercycle deposition structure is generated; and the hypercycle deposition is repeatedly executed until the target film thickness is reached, and the aluminum-doped hafnium oxide film is generated.

Description

Technical Field

[0001] This invention relates to the field of nanofilm material preparation technology, and in particular to an aluminum-doped oxide thin film and its preparation method. Background Technology

[0002] As the feature size of integrated circuits continues to shrink, traditional The physical thickness of the gate dielectric layer has reached its limit (sub-nanometer), leading to severe quantum tunneling effects and excessively high gate leakage current, which in turn affects device power consumption and reliability.

[0003] Hafnium oxide has become an alternative material due to its high dielectric constant, but it is prone to crystallization during high-temperature processes, forming grain boundary leakage channels. Furthermore, it easily forms a low-k silicate layer at the silicon substrate interface, affecting overall dielectric properties. In addition, while plasma-enhanced atomic layer deposition (PEALD) can lower the deposition temperature, the accompanying high-energy particle irradiation may damage sensitive structures and lead to reduced step coverage in high aspect ratio structures. Although elemental doping can improve the stability of amorphous materials, achieving precise control of doping concentration under plasma-free conditions while ensuring process compatibility remains a key technological bottleneck restricting the development of high-performance gate dielectrics.

[0004] Therefore, there is an urgent need to provide a more reliable aluminum-doped oxide thin film and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide an aluminum-doped oxide thin film and its preparation method, which solves the problems in the prior art where high dielectric constant materials are prone to crystallization after high-temperature annealing, leading to increased leakage current, deterioration of interface properties, and structural damage introduced by plasma processing.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing an aluminum-doped oxide thin film, the method comprising: At a preset process temperature, the metal precursor is subjected to alternating pulse delivery; the metal precursor includes a first metal precursor and a second metal precursor; the first metal precursor is a hafnium-containing compound, and the second metal precursor is an aluminum-containing compound; Based on the oxidation reaction of the metal precursor with an oxygen-containing precursor, a hafnium oxide sublayer and an aluminum oxide sublayer are sequentially generated on the surface of a heated substrate. After performing multiple hafnium oxide sublayer growth cycles, an alumina sublayer growth cycle is inserted to generate a supercycle deposition structure. Repeated supercycle deposition is performed until the target film thickness is reached to generate an aluminum-doped hafnium oxide film.

[0007] Optionally, based on an oxygen-containing precursor, the metal precursor is oxidized to sequentially generate a hafnium oxide sublayer and an aluminum oxide sublayer on the surface of a heated substrate, including: At a preset temperature, the heated substrate is subjected to a preset number of first deposition cycles to generate a hafnium oxide layer; After completing the first deposition cycle of a preset number of times, a second deposition cycle is performed on the hafnium oxide sublayer to generate an alumina sublayer.

[0008] Optionally, at a preset temperature, the heated substrate is subjected to a preset number of first deposition cycles to generate a hafnium oxide layer, including: The heated substrate is subjected to a first metal precursor pulse treatment to form a hafnium precursor adsorption layer; The hafnium precursor adsorption layer is subjected to a first inert gas purging treatment to generate a clean hafnium precursor adsorption layer. The clean hafnium precursor adsorption layer is subjected to oxygen-containing precursor pulse treatment to generate a hafnium oxide monolayer. The hafnium oxide monolayer is subjected to a second inert gas purging treatment to generate a surface-regenerated hafnium oxide sublayer.

[0009] Optionally, after completing a first deposition cycle of a preset number of times, a second deposition cycle is performed on the hafnium oxide sublayer to generate an alumina sublayer, including: The surface-regenerated hafnium oxide layer is subjected to a second metal precursor pulse treatment to form an aluminum precursor adsorption layer; The aluminum precursor adsorption layer is subjected to a third inert gas purging treatment to generate a clean aluminum precursor adsorption layer. The clean aluminum precursor adsorption layer is subjected to oxygen-containing precursor pulse treatment to generate an aluminum oxide monolayer. The alumina monolayer is subjected to a fourth inert gas purging treatment to generate a surface-regenerated alumina sublayer.

[0010] Optionally, after repeatedly performing supercycle deposition until the target film thickness is reached to generate an aluminum-doped hafnium oxide film, the method further includes: The aluminum-doped hafnium oxide thin film is annealed in an inert gas atmosphere to achieve film densification and defect control, thereby generating a crystallization-suppressed aluminum-doped hafnium oxide thin film; wherein the aluminum-doped hafnium oxide thin film has an amorphous or microcrystalline structure.

[0011] Optionally, before alternating pulse delivery of the metal precursor at a preset process temperature, the method further includes: Loading a silicon-based substrate or a substrate containing metal gate electrodes to generate a loaded substrate; A high-purity inert gas is introduced into the reaction chamber where the loaded substrate is located, and the chamber is heated to a preset process temperature to generate a stable thermal environment, thus obtaining a heated substrate.

[0012] Optionally, the ratio of the number of hafnium oxide sublayer growth cycles to the number of alumina sublayer growth cycles is 16:1 to 20:1.

[0013] Optionally, the first metal precursor is supplied with saturated vapor pressure by heating the source bottle and is transported to the reaction chamber via a carrier gas, wherein the temperature of the source bottle is 70-75°C; the pulse treatment time of the first metal precursor is 0.1-0.2 seconds. The second metal precursor is operated at room temperature and delivered into the reaction chamber via a carrier gas; the pulse treatment time of the second metal precursor is in the range of 0.01-0.02 seconds.

[0014] Optionally, the oxygen-containing precursor is stored at room temperature and introduced into the reaction chamber via an independent pipeline under pulse control; the oxygen-containing precursor is deionized water, and the pulse treatment time of the oxygen-containing precursor is in the range of 0.01-0.03 seconds; the pressure of the reaction chamber is maintained in the range of 0.1-0.18 Torr.

[0015] Compared with existing technologies, the present invention provides a method for preparing aluminum-doped oxide thin films. This method involves alternating pulse delivery of a metal precursor at a preset process temperature. The metal precursor includes a first metal precursor and a second metal precursor; the first metal precursor is a hafnium-containing compound, and the second metal precursor is an aluminum-containing compound. Based on the oxygen-containing precursor, the metal precursor undergoes an oxidation reaction, sequentially generating a hafnium oxide sublayer and an aluminum oxide sublayer on the surface of a heated substrate. After performing a hafnium oxide sublayer growth cycle, an aluminum oxide sublayer growth cycle is inserted to generate a supercycle deposition structure. This supercycle deposition is repeated until the target film thickness is reached, generating an aluminum-doped hafnium oxide thin film. The technical solution provided by this invention, under plasma-free conditions, periodically introduces aluminum oxide units to suppress hafnium oxide nucleation, improving the film's thermal stability and interface quality. Simultaneously, the excellent conformality of hot-form atomic layer deposition ensures uniform coverage in complex three-dimensional structures, thereby obtaining a high-performance gate dielectric material with low leakage current, high breakdown field strength, and good process compatibility. It achieves the technical effects of low leakage current density, high breakdown field strength, excellent step coverage and no plasma damage.

[0016] In a second aspect, the present invention provides an aluminum-doped oxide thin film, which is prepared by the method for preparing aluminum-doped oxide thin films provided in the first aspect above. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic flowchart of a method for preparing an aluminum-doped oxide thin film provided by the present invention; Figure 2 A schematic diagram of the thermal atomic layer deposition equipment used in the preparation method of an aluminum doped oxide thin film provided by the present invention. Detailed Implementation

[0018] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0019] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0020] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0021] In practical applications, high dielectric constant (High-k) materials, especially hafnium oxide (… Due to its higher dielectric constant (k value typically between 20 and 25) and suitable bandgap, it has become an alternative. The mainstream candidate materials.

[0022] However, pure Thin films face the following challenges in semiconductor back-end processes: (1) Insufficient thermal stability: Crystallization easily occurs during high-temperature annealing (typically >500°C), forming grain boundaries. These grain boundaries are the preferred leakage paths for charge carriers, significantly increasing leakage current.

[0023] (2) Poor interface characteristics: pure Low dielectric constants are easily formed between the silicon substrate and the substrate. Interface defects may occur at the interface layer, affecting the effective dielectric constant and carrier mobility.

[0024] (3) Plasma damage: Although plasma-enhanced atomic layer deposition (PEALD) can reduce the process temperature and increase the film density, the high-energy ions and ultraviolet light in the plasma may damage the substrate surface or the formed channel structure, especially in three-dimensional structures with extremely high aspect ratios (such as 3D NAND or GAA transistors).

[0025] (4) Step coverage limitation: In complex three-dimensional structures, the plasma diffusion and uniformity of PEALD may be limited, resulting in a less ideal step coverage than thermal ALD.

[0026] Therefore, through Doping with a small amount of aluminum (Al) to form an amorphous HfAlO composite film can effectively increase the crystallization temperature of the film, thereby suppressing grain boundary formation and significantly reducing leakage current. Simultaneously, employing a thermal ALD process ensures excellent step coverage in complex three-dimensional structures, avoiding plasma damage. However, precisely controlling the Al doping concentration to optimize electrical properties (the balance between dielectric constant and leakage current) and determining the optimal thermal ALD process window are key challenges.

[0027] To address the aforementioned deficiencies, the present invention provides a technical solution for preparing aluminum-doped hafnium oxide (HfAlO) thin films based on thermal atomic layer deposition (ALD) technology. This falls under the field of nanofilm material preparation technology, specifically relating to the application of ALD technology in semiconductor device manufacturing, particularly in the preparation of dielectric layers for high-k gate dielectric materials, such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and memory devices (such as DRAM and 3D NAND). By optimizing precursor selection, reaction temperature, pulse timing, and the "super-cycle" doping mode, HfAlO thin films with excellent electrical properties and excellent step coverage are prepared without plasma damage. The embodiments provided in this specification will be described below with reference to the accompanying drawings: like Figure 1 As shown, the process may include the following steps: Step 110: At the preset process temperature, the metal precursor is delivered by alternating pulses.

[0028] The preset process temperature indicates that a high-purity inert gas is introduced into the reaction chamber containing the loaded substrate and heated to the preset process temperature to generate a stable thermal environment. Under this stable thermal environment, the metal precursor is delivered via alternating pulses.

[0029] The metal precursor includes a first metal precursor and a second metal precursor; the first metal precursor is a hafnium-containing compound, and the second metal precursor is an aluminum-containing compound. The hafnium-containing compound can be hafnium tert-butoxide (H2N). Tetra(dimethylamino)hafnium (TEMAHf), isopropanol hafnium ( ) and acetylacetone hafnium ( Aluminum-containing compounds can include trimethylaluminum (TMAl), triethylaluminum (TEAl), and aluminum isopropoxide (...). ) and magnesium dicerope ( Although it mainly contains magnesium, it is often used in combination with aluminum-containing precursors, etc. The specific hafnium-containing compound and aluminum-containing compound used can be selected according to the actual application requirements. The embodiments in this specification are only illustrative examples and do not limit the scope of protection of this invention.

[0030] Prior to step 110, the method of the present invention may further include: A silicon-based substrate or a substrate containing a metal gate electrode is loaded to generate a loaded substrate; a high-purity inert gas is introduced into the reaction chamber where the loaded substrate is located, and the chamber is heated to a preset process temperature to generate a stable thermal environment, thus obtaining a heated substrate.

[0031] In the heating substrate step, the silicon substrate can be a fundamental material in semiconductor manufacturing, typically made of single-crystal silicon, possessing a flat surface and good electrical properties. The substrate containing metal gate electrodes can be further processed on the silicon substrate to form a metal gate electrode structure. The metal gate electrode is a key component in devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs), used to control the flow of current. After loading, a high-purity inert gas, such as argon, is introduced into the reaction chamber where the substrate is located. ) or nitrogen ( Inert gases are chemically stable and do not readily react with other substances. The purpose of introducing inert gases is to remove air and other impurities from the reaction chamber, preventing them from adversely reacting with the substrate or reactant gases during subsequent high-temperature processes, thus affecting process performance and product quality.

[0032] The reaction chamber can be heated using a heating device, gradually increasing its temperature to the preset process temperature. Precise temperature control is crucial during heating to ensure the substrate undergoes processing within a uniform temperature environment. Once the temperature within the reaction chamber reaches and stabilizes at the preset process temperature, a stable thermal environment is created. This thermal environment provides the necessary conditions for subsequent processing steps (such as chemical vapor deposition, physical vapor deposition, and thermal oxidation). Under stable thermal conditions, atoms or molecules on the substrate surface possess sufficient energy for migration and recombination, thereby achieving the desired material growth or structural alteration.

[0033] Step 120: Based on the oxygen-containing precursor, the metal precursor is oxidized to sequentially generate a hafnium oxide sublayer and an aluminum oxide sublayer on the surface of the heated substrate.

[0034] Before this step is performed, unreacted precursors and byproducts can be removed by an inert gas purging process to form self-limiting surface reaction conditions; then, the adsorbed metal precursors can be oxidized using deionized water as an oxygen source to generate hafnium oxide sublayers and aluminum oxide sublayers respectively.

[0035] Step 130: After performing multiple hafnium oxide sublayer growth cycles, insert an alumina sublayer growth cycle to generate a supercycle deposition structure.

[0036] Specifically, based on the periodic combination relationship between hafnium oxide sublayer growth cycles and alumina sublayer growth cycles, an alumina sublayer growth cycle can be inserted after N hafnium oxide sublayer growth cycles to generate a supercycle deposition structure. N is an integer and its value range is determined by the predetermined doping concentration requirement.

[0037] Step 140: Repeat the supercycle deposition until the target film thickness is reached to generate an aluminum-doped hafnium oxide film.

[0038] The target film thickness can be set according to the actual application requirements.

[0039] Figure 1The method described herein involves alternating pulse delivery of a metal precursor at a preset process temperature. The metal precursor includes a first metal precursor and a second metal precursor; the first metal precursor is a hafnium-containing compound, and the second metal precursor is an aluminum-containing compound. Based on the oxygen-containing precursor, the metal precursor undergoes an oxidation reaction, sequentially generating a hafnium oxide sublayer and an aluminum oxide sublayer on the heated substrate surface. After performing a hafnium oxide sublayer growth cycle, an aluminum oxide sublayer growth cycle is inserted to generate a supercycle deposition structure. This supercycle deposition is repeated until the target film thickness is reached, generating an aluminum-doped hafnium oxide film. The technical solution provided by this invention, under plasma-free conditions, periodically introduces aluminum oxide units to suppress hafnium oxide phase nucleation, improving the film's thermal stability and interface quality. Simultaneously, the excellent conformality of thermal atomic layer deposition ensures uniform coverage in complex three-dimensional structures, thereby obtaining a high-performance gate dielectric material with low leakage current, high breakdown field strength, and good process compatibility. This achieves the technical effects of low leakage current density, high breakdown field strength, excellent step coverage, and no plasma damage.

[0040] based on Figure 1 In addition to the method described herein, this specification also provides some specific implementation methods of this method, which will be described below.

[0041] First of all, for Figure 1 In a specific implementation, step 120 may include: At a preset temperature, the heated substrate is subjected to a preset number of first deposition cycles to generate a hafnium oxide layer; After completing the first deposition cycle of a preset number of times, a second deposition cycle is performed on the hafnium oxide sublayer to generate an alumina sublayer.

[0042] Furthermore, the first deposition cycle, which generates a hafnium oxide sublayer, may include: The heated substrate is subjected to a first metal precursor pulse treatment to form a hafnium precursor adsorption layer; The hafnium precursor adsorption layer is subjected to a first inert gas purging treatment to generate a clean hafnium precursor adsorption layer. The clean hafnium precursor adsorption layer is subjected to oxygen-containing precursor pulse treatment to generate a hafnium oxide monolayer. The hafnium oxide monolayer is subjected to a second inert gas purging treatment to generate a surface-regenerated hafnium oxide sublayer.

[0043] The second deposition cycle generates an alumina sublayer, which may include: The surface-regenerated hafnium oxide layer is subjected to a second metal precursor pulse treatment to form an aluminum precursor adsorption layer; The aluminum precursor adsorption layer is subjected to a third inert gas purging treatment to generate a clean aluminum precursor adsorption layer. The clean aluminum precursor adsorption layer is subjected to oxygen-containing precursor pulse treatment to generate an aluminum oxide monolayer. The alumina monolayer is subjected to a fourth inert gas purging treatment to generate a surface-regenerated alumina sublayer.

[0044] After step 140, which generates an aluminum-doped hafnium oxide thin film, the method provided by this invention may further include: The aluminum-doped hafnium oxide thin film is annealed in an inert gas atmosphere to achieve film densification and defect control, thereby generating a crystallization-suppressed aluminum-doped hafnium oxide thin film; wherein the aluminum-doped hafnium oxide thin film has an amorphous or microcrystalline structure.

[0045] The complete process steps of the above scheme can be assisted by a thermal atomic layer deposition (TLD) device. A schematic diagram of the TLD device is shown below. Figure 2 As shown, Figure 2 In the middle, pipes 1 and 2 are used to input high-purity nitrogen gas ( Nitrogen is used as both carrier gas and purge gas for the cavity environment. Pipeline 1 and pipeline 2 are used to precisely control the flow rate of nitrogen via flow meter 1 (MFC1) and flow meter 2 (MFC2), respectively.

[0046] The source bottle contains precursor materials (such as TMA, trimethylaluminum or TDMAH, tetramethylaminotitanium, etc.), and the precursor vapor is carried into the reaction chamber by nitrogen as a carrier gas. The output of the source bottle is also controlled by a mass flow meter, and water is also present. It can be used as another precursor or reactant input.

[0047] The reaction chamber is the main site for ALD deposition. The substrate is placed inside, and the temperature of the top of the reaction chamber and the heating plate is set to 250°C. The temperature is then raised to the required process temperature by a heater.

[0048] The base is located inside the reaction chamber and is used to place a substrate with a silicon-based or metal gate electrode such as titanium nitride (TiN) already grown on it.

[0049] By controlling the input of precursors such as TMA and TDMAH, a surface self-limiting reaction occurs with the substrate surface to form a thin film. After each precursor is input, it is purged with high-purity nitrogen to remove unreacted precursors and byproducts.

[0050] Vacuum pumps are used to establish a vacuum environment within the reaction chamber, ensuring that there are no impurities interfering with the deposition process and to help with the discharge of purging gases.

[0051] The heater heats the reaction chamber and substrate to a preset process temperature, ensuring good reactivity of the precursor on the substrate surface. After deposition, rapid thermal annealing is performed in a nitrogen atmosphere to improve the crystallinity and electrical properties of the film.

[0052] use Figure 2 The thermal atomic layer deposition equipment in the system achieves high-quality thin film atomic layer deposition by precisely controlling gas flow rate, precursor input sequence and reaction temperature. The entire system is carried out under inert gas protection to avoid external contamination and ensure the purity and performance of the film.

[0053] use Figure 2 When using a thermal atomic layer deposition apparatus to deposit aluminum-doped oxide thin films according to this scheme, the complete steps may include: (1) Substrate preparation: Place a silicon-based substrate or a substrate with a metal gate electrode such as titanium nitride (TiN) on a base inside the ALD reaction chamber.

[0054] (2) Chamber environment and substrate heating: The reaction chamber is heated to the working temperature, and a high-purity inert gas (such as...) is used. The substrate is then purged and heated to the preset process temperature.

[0055] (3) Thermal ALD deposition cycle: a. Hafnium oxide ( Growth cycle (cycle a): Tetra(dimethylamino)hafnium (TDMAH) was used as the hafnium source precursor, and the pulse duration was 0.12 s.

[0056] Then an inert gas ( Purge for 20 seconds.

[0057] Deionized water ( As an oxygen source, the pulse duration is 0.01-0.05 s.

[0058] Inert gas was used again ( Purge for 20 seconds.

[0059] b. Alumina ( Growth cycle (cycle b): Trimethylaluminum (TMA) was used as the aluminum source precursor, and the pulse time was 0.015 s.

[0060] Then an inert gas ( Purge for 20 seconds.

[0061] Deionized water ( As the oxygen source, the pulse duration is 0.02 s.

[0062] Inert gas was used again ( Purge for 20 seconds.

[0063] Supercycle doping mode: By combining the two sub-cycles a and b mentioned above, a "supercycle" structure is formed. Specifically, after every N hafnium oxide growth sub-cycles (cycle a), one alumina growth sub-cycle (cycle b) is inserted.

[0064] Total deposition thickness control: Repeat the above supercycle until the target film thickness is reached.

[0065] Post-deposition annealing: After deposition, in an inert gas ( Under a suitable atmosphere, rapid thermal annealing is performed, with an annealing temperature range of 500°C-700°C and an annealing time of 30-60 seconds.

[0066] It is understood that the equipment used in this invention is not limited to a specific manufacturer's model; as long as it has an independent precursor control channel, precise temperature control capability, and programmed timing control function, it can be implemented. The carrier gas can be argon or other inert gases, but nitrogen is preferred due to its low cost and high purity. The use of terms such as "first," "second," "third," and "fourth inert gas" in the scheme does not mean they are different inert gases; they can all be nitrogen. However, the terms "first" and "second" are used to distinguish them when applied in different steps.

[0067] The reaction chamber can be configured with multiple precursor supply channels, corresponding to TDMAH, TMA, and... The system features independent injection paths, each equipped with a switching valve for precise pulse timing control. The programmable controller is programmed to automatically execute the combined logic of loops a and b according to a preset sequence. It supports user-defined input of supercycle ratio, total number of cycles, and annealing curve parameters, converting these into executable process steps. The central control system can also dynamically adjust heating power based on feedback signals from the temperature sensor array to maintain stable process temperature. It is also equipped with a fault diagnosis module to monitor precursor delivery pressure fluctuations, valve response delays, and temperature deviations, generating corresponding alarm information.

[0068] The fabrication method provided by this invention is applicable to various semiconductor device manufacturing scenarios. For example, in metal-oxide-semiconductor field-effect transistors (MOSFETs), using the HfAlO thin film prepared by this invention as a high-k gate dielectric layer can significantly reduce gate leakage current and improve device reliability; in dynamic random access memory (DRAM) capacitor structures, its use as a dielectric layer can achieve uniform coverage within deep-hole structures, increasing the capacitance per unit area; in 3D NAND flash memory word line stacking processes, its use as an interlayer isolation dielectric can withstand high-temperature back-end processes without over-crystallization, maintaining good insulation performance. Therefore, this invention is not only applicable to planar devices, but can also be extended to gate dielectric integration applications in FinFETs, GAA FETs, and emerging ferroelectric devices, possessing good potential for industrialization and promotion.

[0069] Next, we will use specific practical examples to illustrate the detailed implementation process of the method for preparing an aluminum-doped oxide thin film provided by this invention: For example, the substrate cavity heating Heater and Top temperature are set to 250-300°C, preferably 250°C.

[0070] Hafnium source: tetra(dimethylamino)hafnium (TDMAH), the source bottle temperature is heated to 70-75°C, preferably 75°C, to provide a stable and sufficiently high saturated vapor pressure.

[0071] Aluminum source: Trimethylaluminum (TMA) is selected, and the source bottle is kept at room temperature; TMA can usually be used effectively at room temperature due to its extremely high reactivity and high vapor pressure.

[0072] Oxygen source: Deionized water ( The source bottle is kept at room temperature.

[0073] Carrier gas and pressure: High-purity nitrogen (not less than 99.999%) is used. The flow meters 1 and 2 are set to 10 sccm. The pressure in the reaction chamber is maintained in the range of 0.1-0.18 Torr, preferably 0.15 Torr.

[0074] Under the above conditions, the specific process for growing the hafnium oxide sublayer (i.e., subcycle a) can be as follows: Tetra(dimethylamino)hafnium pulse: The hafnium source pulse is activated, with a pulse duration ranging from 0.1 to 0.2 seconds, preferably 0.12 seconds. Precursor molecules are delivered into the reaction chamber by carrier gas nitrogen through pipe 2, and the precursor molecules adsorb onto the substrate surface.

[0075] Purging 1: Purging with nitrogen carrier gas from pipe 2 for 10-20 seconds, preferably 20 seconds, to thoroughly remove unreacted tetra(dimethylamino)hafnium molecules and physical adsorbates.

[0076] Pulse: On The pulse lasts 0.02 seconds. Nitrogen gas, carried by the carrier gas in pipeline 1, will... Molecules are introduced into the reaction chamber, where water molecules undergo a surface self-limiting reaction with tetra(dimethylamino)hafnium molecules adsorbed on the surface, forming... Monolayer, and regenerated hydroxyl surface.

[0077] Purging 2: Purge with nitrogen for 10-20 seconds, preferably 20 seconds, to remove reaction byproducts and excess water molecules.

[0078] Under the above conditions, the specific process for growing the alumina sublayer (sub-cycle b-doped layer) can be as follows: Trimethylaluminum pulse: The aluminum source pulse is activated, with a pulse duration ranging from 0.01 to 0.02 seconds, preferably 0.015 seconds. Precursor molecules are delivered into the reaction chamber by nitrogen carrier gas through pipe 2. TMA has extremely high reactivity, and a short pulse is sufficient to achieve saturation adsorption.

[0079] Purging 1: The nitrogen purging time ranges from 15 to 25 seconds, preferably 20 seconds.

[0080] Pulse: On The source pulse has a pulse duration of 0.01-0.03 seconds, preferably 0.02 seconds. Water molecules are introduced into the reaction chamber via nitrogen carrier gas from pipe 1. The water molecules react with TMA molecules adsorbed on the surface to form… Monolayer.

[0081] Purging 2: Purge with nitrogen for 15-25 seconds, preferably 20 seconds. This removes reaction byproducts and excess water molecules.

[0082] The process of achieving a supercycle deposition structure (HfAlO thin film deposition) may include: Ratio: Set to 18:1. That is: execute continuously (16-20 times), preferably 18 sub-cycles a (deposition). Then execute sub-loop b (deposition) once. ).

[0083] Total number of cycles and film thickness: Repeat the above supercycle 10-20 times, preferably 15 times. The total number of cycles for the entire deposition process is... The final film thickness was approximately 26 nm.

[0084] Post-deposition annealing process: After deposition, in Under certain conditions, the temperature is rapidly raised to 600°C and held for 60 seconds. This effectively eliminates oxygen vacancy defects inside the thin film, increases film density and densification, and utilizes the crystallization suppression effect of Al doping to ensure that the film remains in a highly amorphous or microcrystalline state, thereby obtaining optimal electrical performance.

[0085] Al elements are embedded in periodic thin layers. In the matrix, effective suppression is achieved during subsequent annealing processes. Grain nucleation and growth. Understandably, the number of cycles N can be adjusted according to the target doping concentration, taking values ​​between 16 and 20, for example, a ratio of 16:1 or 20:1, to study the effect of different Al distribution densities on the crystallization behavior of thin films.

[0086] The aluminum-doped hafnium oxide thin film prepared by the aforementioned method for preparing aluminum-doped oxide thin films provided by this invention can be applied in semiconductor devices. Specifically, the semiconductor device may include the aluminum-doped hafnium oxide thin film prepared by the aforementioned method for preparing aluminum-doped oxide thin films. The aluminum-doped hafnium oxide thin film can be disposed on a substrate as a gate dielectric layer or a capacitor dielectric layer. In the semiconductor device, the memory device can be a dynamic random access memory or a three-dimensional flash memory.

[0087] In the foregoing embodiments, the temperature and pressure parameters of the reaction chamber can be monitored in real time during the deposition process. Based on the deviation of the monitored temperature and pressure parameters from preset parameter ranges, the power of the heating module and the purge gas flow rate are automatically adjusted. When abnormal parameters are detected, an alarm signal is triggered and the deposition process is paused to ensure process stability and repeatability.

[0088] The specific parameters and parameter ranges in the above embodiments can be adjusted according to actual process requirements. For example, the precursor pulse time can be adjusted according to the precursor vapor pressure and reactivity, the purge time can be optimized according to the reaction chamber structure and deposition temperature, the supercycle ratio can be adjusted according to the required aluminum doping concentration, and the annealing temperature and time can be optimized according to the film thickness and device structure. These adjustments are all within the scope of protection of this invention.

[0089] The technical solution provided by this invention avoids plasma damage by employing a hot atomic layer deposition process combined with a supercyclic doping mode, while ensuring excellent step coverage in complex three-dimensional structures. By precisely controlling the aluminum doping concentration and distribution, crystallization of the film during high-temperature annealing is effectively suppressed, reducing grain boundary formation and thus significantly lowering leakage current density. Optimizing the precursor pulse timing and purge time ensures the self-limiting and uniformity of film growth, improving film density and interface quality. Annealing eliminates oxygen vacancy defects within the film, further optimizing electrical properties. The synergistic effect of these technical features results in an aluminum-doped hafnium oxide film exhibiting excellent performance with high breakdown field strength, wide bandgap, and low leakage current. More specifically, the technical effects include at least: (1) Ultra-low leakage current: compared with undoped pure Compared to crystallization after annealing, the HfAlO thin film prepared in this invention exhibits a leakage current density reduction of nearly two orders of magnitude under a 1V bias voltage, which is crucial for reducing device power consumption.

[0090] (2) Excellent step coverage and morphological consistency: In complex three-dimensional structures with an aspect ratio greater than 10:1 (such as trenches or high aspect ratio holes), this process can achieve an excellent step coverage of more than 95% (defined as the ratio of the bottom film thickness to the top film thickness), ensuring the uniformity and reliability of the device structure.

[0091] (3) High breakdown field strength and wide bandgap: By doping with high bandgap materials The effective band gap width of the HfAlO thin film prepared by this invention can be increased from pure... The voltage was increased from approximately 5.8 eV to over 6.2 eV, effectively increasing the electron tunneling barrier. This directly led to a significant increase in the breakdown field strength of the thin film from the pure electron tunneling barrier. The voltage has been increased from approximately 6 MV / cm to over 8.5 MV / cm, significantly improving the reliability and operating voltage range of the device.

[0092] (4) No plasma damage: It completely avoids the physical and electrical damage that the PEALD process may cause to the surface and internal defects of sensitive semiconductor devices (such as channel damage and interface state increase), which is crucial for ultra-thin gate dielectrics and high mobility channels in advanced processes.

[0093] Based on the same idea, the present invention also provides an aluminum-doped oxide thin film, which is prepared by the aforementioned method for preparing aluminum-doped oxide thin films.

[0094] It should be noted that the aluminum-doped hafnium oxide thin film prepared by the method provided in this invention can be used in semiconductor devices. Specifically, the aluminum-doped hafnium oxide thin film prepared by the above method can be disposed on a substrate as a gate dielectric layer or capacitor dielectric layer to form a semiconductor device. This semiconductor device can be applied in memory devices such as dynamic random access memory or 3D flash memory. In complex three-dimensional structures, the aluminum-doped hafnium oxide thin film prepared by this method can achieve a step coverage of over 95% and completely avoid plasma damage.

[0095] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0096] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for producing an aluminum-doped oxide thin film, characterized by comprising the steps of: The method comprises: ​ alternately pulse delivering the metal precursors at a preset process temperature; the metal precursors comprise a first metal precursor and a second metal precursor; the first metal precursor is a hafnium-containing compound, and the second metal precursor is an aluminum-containing compound; oxidizing the metal precursors based on an oxygen-containing precursor to sequentially generate a hafnium oxide sublayer and an aluminum oxide sublayer on a heated substrate surface; after performing a plurality of hafnium oxide sublayer growth cycles, inserting an aluminum oxide sublayer growth cycle to generate a supercycle deposition structure; repeating the supercycle deposition until a target film thickness is reached to generate an aluminum-doped hafnium oxide film.

2. The method of claim 1, wherein, The method for oxidizing the metal precursors based on an oxygen-containing precursor to sequentially generate a hafnium oxide sublayer and an aluminum oxide sublayer on a heated substrate surface comprises: at a preset temperature, sequentially performing a preset number of first deposition cycles on the heated substrate to generate a hafnium oxide sublayer; after completing the preset number of first deposition cycles, performing a second deposition cycle on the hafnium oxide sublayer to generate an aluminum oxide sublayer.

3. The method of claim 2, wherein, At a preset temperature, sequentially performing a preset number of first deposition cycles on the heated substrate to generate a hafnium oxide sublayer comprises: pulse processing the heated substrate with the first metal precursor to form a hafnium precursor adsorption layer; purging the hafnium precursor adsorption layer with a first inert gas to generate a clean hafnium precursor adsorption layer; pulse processing the clean hafnium precursor adsorption layer with an oxygen-containing precursor to generate a hafnium oxide monolayer; purging the hafnium oxide monolayer with a second inert gas to generate a surface-regenerated hafnium oxide sublayer.

4. The method of claim 2, wherein, After completing the preset number of first deposition cycles, performing a second deposition cycle on the hafnium oxide sublayer to generate an aluminum oxide sublayer comprises: pulse processing the surface-regenerated hafnium oxide sublayer with the second metal precursor to form an aluminum precursor adsorption layer; purging the aluminum precursor adsorption layer with a third inert gas to generate a clean aluminum precursor adsorption layer; pulse processing the clean aluminum precursor adsorption layer with an oxygen-containing precursor to generate an aluminum oxide monolayer; purging the aluminum oxide monolayer with a fourth inert gas to generate a surface-regenerated aluminum oxide sublayer.

5. The method of claim 1, wherein, After repeating the supercycle deposition until a target film thickness is reached to generate an aluminum-doped hafnium oxide film, the method further comprises: annealing the aluminum-doped hafnium oxide film in an inert gas atmosphere to complete film densification and defect regulation, generating a crystallization-inhibited aluminum-doped hafnium oxide film; wherein the aluminum-doped hafnium oxide film has an amorphous or microcrystalline structure.

6. The method of claim 1, wherein, Before alternately pulse delivering the metal precursors at a preset process temperature, the method further comprises: loading a silicon-based substrate or a substrate containing a metal gate electrode to generate a loaded substrate; introducing high-purity inert gas into the reaction chamber where the loaded substrate is located, and heating to a preset process temperature to generate a stable thermal environment, obtaining a heated substrate.

7. The method of claim 1, wherein, The number ratio of the hafnium oxide sublayer growth cycle to the aluminum oxide sublayer growth cycle is 16:1 to 20:

1.

8. The method of claim 1, wherein, The first metal precursor provides saturated vapor pressure by heating the source bottle, and is delivered into the reaction cavity by carrier gas, wherein the source bottle temperature is 70-75°C; the first metal precursor pulse treatment time ranges from 0.1 to 0.2 seconds; The second metal precursor operates at room temperature and is delivered into the reaction cavity by carrier gas; the second metal precursor pulse treatment time ranges from 0.01 to 0.02 seconds.

9. The method of claim 1, wherein, The oxygen-containing precursor is stored at room temperature and introduced into the reaction cavity under pulse control via an independent pipeline; the oxygen-containing precursor is deionized water, the oxygen-containing precursor pulse treatment time ranges from 0.01 to 0.03 seconds; the reaction cavity pressure is maintained in the range of 0.1-0.18 Torr.

10. An aluminum-doped oxide thin film, characterized by, The aluminum-doped oxide thin film is prepared by the method of any one of claims 1-9.

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