Preparation method of elemental molybdenum film

Abstract

The embodiment of the invention provides a preparation method of an elemental molybdenum film, and the method comprises the steps: placing a semiconductor substrate in a reaction cavity of atomic layer deposition equipment, and enabling the reaction cavity to meet a preset condition; an atomic layer deposition cycle is repeatedly executed until an elemental molybdenum film with a set thickness is formed on the surface of the semiconductor substrate, and the atomic layer deposition cycle comprises the following steps that a gas-phase molybdenum precursor is introduced into the reaction cavity so that the molybdenum precursor can be adsorbed on the surface of the semiconductor substrate; and introducing a gas-phase silane precursor into the reaction cavity so as to form an elemental molybdenum film on the surface of the semiconductor substrate through chemical reaction between the silane precursor and the molybdenum precursor. According to the technical scheme provided by the embodiment of the invention, the low-roughness elemental molybdenum film can be prepared based on the atomic layer deposition technology.

Description

Technical Field

[0001] The present application relates to the technical field of thin film preparation, and more particularly, to a method for preparing a single-element molybdenum thin film. Background Art

[0002] Molybdenum (Mo) is a refractory metal with a low coefficient of thermal expansion, electrical conductivity, high melting point, and relatively short electron mean free path. At present, molybdenum is considered to be an excellent substitute for advanced interconnects replacing copper and tungsten in large-scale integrated circuits and memories. Currently, the traditional PVD method is often used to prepare single-element molybdenum thin films, but this method cannot meet the requirements of longer, narrower, and denser interconnects for the new generation of chips. Due to the excellent three-dimensional conformal property and precise thickness control at the atomic layer level of ALD technology, this technology has received extensive attention in the field of semiconductor preparation. Although there are also a small number of single-element molybdenum thin films prepared by ALD technology at present, the prepared single-element molybdenum thin films generally have the defect of relatively high roughness, resulting in poor applicability. Summary of the Invention

[0003] An embodiment of the present application provides a method for preparing a single-element molybdenum thin film. Based on the technical solution provided by the present application, a single-element molybdenum thin film with low roughness can be prepared based on atomic layer deposition technology.

[0004] Other features and advantages of the present application will become apparent through the following detailed description, or be learned in part through the practice of the present application.

[0005] According to an embodiment of the present application, a method for preparing a single-element molybdenum thin film is provided. The method includes: placing a semiconductor substrate in a reaction chamber of an atomic layer deposition device, where the reaction chamber meets a preset condition; repeating an atomic layer deposition cycle until a single-element molybdenum thin film with a set thickness is formed on the surface of the semiconductor substrate. The atomic layer deposition cycle includes the following steps: introducing a gaseous molybdenum precursor into the reaction chamber to adsorb the molybdenum precursor on the surface of the semiconductor substrate; introducing a gaseous silane precursor into the reaction chamber to chemically react the silane precursor with the molybdenum precursor to form a single-element molybdenum thin film on the surface of the semiconductor substrate.

[0006] In some embodiments of the present application, based on the foregoing solution, the preset condition includes: the reaction chamber is in a vacuum state and the temperature is 100 - 400 °C.

[0007] In some embodiments of the present application, based on the foregoing solution, the introduction time of the molybdenum precursor is 0.01 - 5 s; the introduction time of the silane precursor is 0.01 - 3 s.

[0008] In some embodiments of the present application, based on the foregoing solution, the temperature of the molybdenum precursor is 0 to 50 °C; the temperature of the silane precursor is 0 to 50 °C.

[0009] In some embodiments of the present application, based on the foregoing solution, the semiconductor substrate includes one of single-crystalline silicon, silicon oxide, silicon nitride, sapphire, and glass; the molybdenum precursor includes one or more of MoCl5, MoO2Cl2, and MoF6.

[0010] In some embodiments of the present application, based on the foregoing solution, the atomic layer deposition cycle further includes: introducing an inert gas into the reaction chamber before and after introducing the molybdenum precursor or the silane precursor into the reaction chamber, and during the process of introducing the silane precursor into the reaction chamber.

[0011] In some embodiments of the present application, based on the foregoing solution, when introducing the inert gas into the reaction chamber, the flow rate of the inert gas is 10 to 200 sccm.

[0012] In some embodiments of the present application, based on the foregoing solution, after introducing the molybdenum precursor into the reaction chamber and before introducing the silane precursor into the reaction chamber, an inert gas is introduced into the reaction chamber to purge the reaction chamber. During the purging of the reaction chamber, the purging time is 1 to 100 s, and the pressure of the reaction chamber is maintained at 0.1 to 2 Torr.

[0013] In some embodiments of the present application, based on the foregoing solution, after introducing the silane precursor into the reaction chamber, an inert gas is introduced into the reaction chamber to purge the reaction chamber. During the purging of the reaction chamber, the purging time is 3 to 120 s, and the pressure of the reaction chamber is maintained at 0.1 to 2 Torr.

[0014] In some embodiments of the present application, based on the foregoing solution, before placing the semiconductor substrate in the reaction chamber of the atomic layer deposition equipment, the semiconductor substrate is pretreated to remove impurities on the surface of the semiconductor substrate.

[0015] In the technical solution of the present application, during the process of preparing a molybdenum thin film based on atomic layer deposition technology, after placing a semiconductor substrate in a reaction chamber of an atomic layer deposition device that meets preset conditions; by repeatedly performing atomic layer deposition cycles, a molybdenum thin film with a set thickness can be formed on the surface of the semiconductor substrate. Among them, the atomic layer deposition cycle includes the following steps: introducing a gaseous molybdenum precursor into the reaction chamber to adsorb the molybdenum precursor on the surface of the semiconductor substrate; introducing a gaseous silane precursor into the reaction chamber to chemically react the silane precursor with the molybdenum precursor to form a molybdenum thin film on the surface of the semiconductor substrate. Since the key to the quality of the thin film prepared by atomic layer deposition technology lies in the selection of the precursor, in the technical solution of the present application, the molybdenum precursor used has a small steric hindrance and relative molecular mass, and at the same time has characteristics such as high volatility, saturated vapor pressure, thermal stability, and reaction activity. When combined with the selected silane precursor, it has high reaction activity and the reaction has self-limitation, enabling the preparation of a molybdenum thin film with advantages such as low roughness, high conformal property, and low thin film impurity content, thereby improving the application performance of the molybdenum thin film.

[0016] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0018] Figure 1 A flowchart showing the preparation method of a molybdenum thin film according to an embodiment of the present application;

[0019] Figure 2 An image schematic diagram of a molybdenum thin film according to an embodiment of the present application;

[0020] Figure 3 A schematic diagram of the sheet resistance of a 50-nm-thick tungsten thin film at different growth temperatures at the present stage;

[0021] Figure 4 An AFM image schematic diagram of a molybdenum thin film according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the drawings.

[0023] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art can additionally design regions / layers with different shapes, sizes, and relative positions according to actual requirements.

[0024] In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element can be directly on the other layer / element, or there can be an intermediate layer / element between them. Additionally, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element can be "under" the other layer / element. In the context of the present disclosure, similar or identical components may be denoted by the same or similar reference numerals.

[0025] In order to enable those skilled in the art to better understand the technical solutions of the present application, the background technology related to the present application will be elaborated in detail below.

[0026] In modern large-scale integrated circuits and memories, copper (Cu) is usually used as the interconnect material in new IC logics, and tungsten (W) is used as the word line and contact material in 3D NAND storage devices. However, when the critical interconnect size is lower than the electron mean free path (MFP) of Cu and W, the resistivity of ultra-thin interconnects will be greatly increased due to the enhanced electron scattering on the surface and interface. Since both Cu and W have relatively long MFPs, other metals are being explored to replace Cu and W at the present stage.

[0027] Molybdenum (Mo) is a refractory metal with the characteristics of low coefficient of thermal expansion, high conductivity and melting point, and relatively short MFP. Its high thermal stability and expected resistance to electromigration can also reduce the need for a high-resistance diffusion barrier. Therefore, Mo can be regarded as a representative of reliability and is considered an excellent alternative to replace Cu and W for advanced interconnects.

[0028] At the present stage, elemental molybdenum thin films are usually prepared by traditional PVD (Physical Vapor Deposition). However, due to the continuous miniaturization of the semiconductor industry, new generation chips are having longer, narrower, and more closely spaced interconnects, making this traditional method unable to meet the requirements.

[0029] The ALD (Atomic Layer Deposition) technology has excellent three-dimensional conformal properties, two-dimensional flatness, good film adhesion, and precise thickness control at the atomic layer level. Therefore, this technology has received extensive attention in the field of semiconductor manufacturing.

[0030] Currently, there are a few reports on the preparation of molybdenum metal films by ALD technology, mainly including the following two methods:

[0031] The first method is to deposit a layer of molybdenum precursor on the sample surface by ALD technology, and then grow a molybdenum metal film through a reaction with hydrogen. This method has problems such as high reaction temperature (above 600 °C), the need to heat the molybdenum precursor, low growth rate, and high roughness.

[0032] The second method is to grow a molybdenum metal film by reacting molybdenum chloride gas with Zn powder through ALD technology. This method has problems such as high reaction temperature (above 400 °C), particles and impurities in the film, and high roughness.

[0033] Since atomic layer deposition technology is based on a series of chemical reaction processes on the substrate surface, different precursors affect the reaction temperature, film composition, roughness, uniformity, adhesion, and other physical and chemical properties of the prepared film. Therefore, the selection of precursors is particularly important for the preparation of molybdenum metal films. Generally, the selected precursors need to have relatively high reaction activity, high saturated vapor pressure, relatively high stability, and inert reaction products. Secondly, the synthesis cost, purity, and economy need to be considered. Therefore, based on these factors, this application proposes a method for preparing a molybdenum metal film to obtain a molybdenum metal film with relatively low roughness.

[0034] To better understand the technical solution of this application, the technical solution of this application will be described in detail below in combination with specific embodiments. It should be understood that the specific features in the embodiments of the present disclosure are detailed descriptions of the technical solution of this application, rather than limitations on the technical solution of this application. Without conflict, the technical features in the embodiments of this application and the embodiments can be combined with each other.

[0035] See Figure 1 , which shows a schematic flow chart of a method for preparing a molybdenum metal film according to an embodiment of this application, specifically including the following steps 110 to 140:

[0036] Step 110: Place a semiconductor substrate in the reaction chamber of an atomic layer deposition device, and the reaction chamber meets preset conditions.

[0037] In this application, optionally, the semiconductor substrate includes one of single-crystalline silicon, silicon oxide, silicon nitride, sapphire, and glass.

[0038] It is understandable that the semiconductor substrate required for preparing the molybdenum thin film in this application has no substrate selectivity and is compatible with semiconductor substrates of different materials.

[0039] In this application, optionally, the preset conditions may include: the reaction chamber is in a vacuum state and the temperature is 100 - 400 °C.

[0040] Furthermore, the temperature included in the preset conditions is more preferably 100 - 300 °C.

[0041] Furthermore, the temperature included in the preset conditions is most preferably 100 - 250 °C. Specifically, it may be one of 125 °C, 150 °C, and 175 °C.

[0042] In this application, in order to ensure that the cavity and pipeline of the reaction chamber in the atomic layer deposition equipment are in a dry state without water vapor residue, before placing the semiconductor substrate into the reaction chamber, the atomic layer deposition equipment needs to be evacuated and heated to make the reaction chamber of the atomic layer deposition equipment meet the preset conditions.

[0043] In some embodiments of this application, in order to ensure that the semiconductor substrate placed in the reaction chamber of the atomic layer deposition equipment is in a clean state without surface contamination and impurities, the following step 100 may also be performed before step 110:

[0044] Step 100, pre-treat the semiconductor substrate to remove impurities on the surface of the semiconductor substrate.

[0045] Specifically, the method for pre-treating the semiconductor substrate can be selected according to the actual situation, and this application does not limit it here. For example, in step 100, the specific implementation method can be performed according to the following steps 101 to 106:

[0046] Step 101, ultrasonically clean the semiconductor substrate with deionized water for 5 - 10 minutes to remove dust and residues on the surface of the semiconductor substrate.

[0047] Step 102, clean the semiconductor substrate with a mixed solution of concentrated sulfuric acid and hydrogen peroxide for 5 - 10 minutes to remove organic substances, heavy metals, and particulate contamination on the surface of the semiconductor substrate.

[0048] Step 103, sequentially clean the semiconductor substrate with hydrogen peroxide, ammonia water, and water for 5 - 10 minutes to remove particles and organic substances on the surface of the semiconductor substrate.

[0049] Step 104, sequentially clean the semiconductor substrate with hydrogen peroxide, hydrochloric acid, and water for 5 - 10 minutes to remove particles and metals on the surface of the semiconductor substrate.

[0050] Step 105: Rinse the semiconductor substrate with ultrapure water for 1 min to 10 min to remove the ions on the surface of the semiconductor substrate.

[0051] Step 106: Dry the semiconductor substrate with high-purity nitrogen.

[0052] In this embodiment, it can be understood that by pretreating the semiconductor substrate, the adsorbed impurities on the surface of the substrate can be removed, and thus the adsorption of the precursor on the surface of the semiconductor substrate can be improved.

[0053] Continue to refer to Figure 1 , Step 120: Repeat the atomic layer deposition cycle until a single-layer molybdenum film with a set thickness is formed on the surface of the semiconductor substrate. The atomic layer deposition cycle includes the following steps:

[0054] Step 130: Introduce a gaseous molybdenum precursor into the reaction chamber to adsorb the molybdenum precursor on the surface of the semiconductor substrate.

[0055] Step 140: Introduce a gaseous silane precursor into the reaction chamber to form a single-layer molybdenum film on the surface of the semiconductor substrate through a chemical reaction between the silane precursor and the molybdenum precursor.

[0056] In this application, it should be noted that the number of times of repeating the atomic layer deposition cycle is associated with the set thickness of the required single-layer molybdenum film. Since only one molybdenum atomic layer can be produced in one atomic layer deposition cycle, the technical solution of this application can accurately control the thickness of the single-layer molybdenum film.

[0057] In this application, optionally, the number of times of repeating the atomic layer deposition cycle can be 1 to 1000 times.

[0058] Furthermore, more preferably, the number of times of repeating the atomic layer deposition cycle can be 20 to 800 times.

[0059] Furthermore, most preferably, the number of times of repeating the atomic layer deposition cycle can be 20 to 500 times.

[0060] Based on different numbers of times of repeating the atomic layer deposition cycle, the thickness of the prepared single-layer molybdenum film is 20 nm to 200 nm.

[0061] Some implementation details of the above Step 130 are elaborated below:

[0062] In this application, optionally, the molybdenum precursor may include one or more of MoCl5, MoO2Cl2, and MoF6.

[0063] In this application, optionally, the temperature of the molybdenum precursor introduced into the reaction chamber of the atomic layer deposition equipment is 0 to 50 °C.

[0064] Furthermore, more preferably, the temperature of the molybdenum precursor can be one of 20 °C, 25 °C, 30 °C or 35 °C.

[0065] Thus, based on the molybdenum precursor selected in this application, there is no need to perform high-temperature treatment on the introduced molybdenum precursor. The process conditions are not harsh, and it focuses on the low-temperature preparation process using atomic layer deposition technology to obtain a high molybdenum thin film growth rate and precisely controlled molybdenum thin film thickness.

[0066] In this application, optionally, the introduction time of the gaseous molybdenum precursor into the reaction chamber is 0.01 to 5 s.

[0067] Furthermore, more preferably, the introduction time of the molybdenum precursor can be 0.05 to 5 s.

[0068] Furthermore, most preferably, the introduction time of the molybdenum precursor can be 0.1 to 3 s. Specifically, it can be one of 0.3 s, 0.5 s, 0.88 s or 1.0 s.

[0069] In this application, optionally, the molybdenum precursor can be introduced into the reaction chamber in the form of a pulse. Specifically, a single pulse can be used to introduce the molybdenum precursor into the reaction chamber.

[0070] In this application, optionally, before step 130, an inert gas can also be introduced into the reaction chamber. That is, before introducing the molybdenum precursor into the reaction chamber, an inert gas is introduced into the reaction chamber.

[0071] In this application, optionally, when introducing the inert gas into the reaction chamber, the flow rate of the inert gas is 10 to 200 sccm.

[0072] Furthermore, more preferably, the flow rate of the inert gas can be 10 to 180 sccm.

[0073] Furthermore, most preferably, the flow rate of the inert gas can be 50 to 150 sccm. Specifically, it can be one of 70 sccm, 90 sccm, 110 sccm, and 130 sccm.

[0074] It can be understood that in this embodiment, introducing an inert gas into the reaction chamber before step 130 can keep the pressure in the reaction chamber stable.

[0075] In this application, optionally, after step 130 and before step 140, that is, after introducing the molybdenum precursor into the reaction chamber and before introducing the silane precursor into the reaction chamber, an inert gas can also be introduced into the reaction chamber. When introducing the inert gas into the reaction chamber, the flow rate of the inert gas is 10 - 200 sccm.

[0076] Specifically, an inert gas can be introduced into the reaction chamber to purge the reaction chamber. When purging the reaction chamber, the purge time is 1 - 100 s, and the pressure of the reaction chamber is maintained at 0.1 - 2 Torr.

[0077] Furthermore, more preferably, the purge time can be 5 - 90 s.

[0078] Furthermore, most preferably, the purge time can be 10 - 80 s.

[0079] It can be understood that after step 130, introducing an inert gas into the reaction chamber can remove the molybdenum precursor that is not adsorbed by the semiconductor substrate in the reaction chamber, that is, it can remove the excess molybdenum precursor in the reaction chamber.

[0080] Some implementation details of the above step 140 are elaborated below:

[0081] In this application, optionally, the silane precursor includes SiH4, Si2H6, Si3H8, Si4H 10 and other silanes that conform to Si x H 2x+2 ratio, one or more of them.

[0082] In step 140, the silane precursor eliminates elements such as F or Cl in the molybdenum precursor, enabling the growth of a molybdenum atomic layer on the surface of the semiconductor substrate. For example, a chemical reaction occurs between MoCl5 and SiH4, generating Si and HCl.

[0083] In this application, optionally, the temperature of the silane precursor introduced into the reaction chamber of the atomic layer deposition equipment is 0 - 50 °C.

[0084] Furthermore, more preferably, the temperature of the silane precursor can be one of 20 °C, 25 °C, 30 °C, or 35 °C.

[0085] Thus, based on the silane precursor selected in this application, there is no need to perform high-temperature treatment on the introduced silane precursor. The process conditions are not harsh, focusing on the low-temperature preparation process using atomic layer deposition technology, resulting in a high molybdenum thin film growth rate and precisely controlled molybdenum thin film thickness.

[0086] In this application, optionally, the introduction time of the silane precursor into the reaction chamber of the atomic layer deposition equipment is 0.01 to 3 s.

[0087] Furthermore, the introduction time of the silane precursor is more preferably 0.05 to 2 s.

[0088] Furthermore, the introduction time of the silane precursor is most preferably 0.1 to 1.5 s. Specifically, it can be one of 0.5 s, 0.8 s, 1.0 s, or 1.2 s.

[0089] In this application, optionally, the silane precursor can be introduced into the reaction chamber in the form of pulses. Specifically, a single pulse can be used to introduce the silane precursor into the reaction chamber.

[0090] In this application, optionally, during the process of step 140, that is, during the process of introducing the silane precursor into the reaction chamber, an inert gas can also be introduced into the reaction chamber. Among them, when the inert gas is introduced into the reaction chamber, the flow rate of the inert gas is 10 to 200 sccm.

[0091] Furthermore, the flow rate of the inert gas is more preferably 10 to 150 sccm.

[0092] Furthermore, the flow rate of the inert gas is most preferably 20 to 120 sccm. Specifically, it can be one of 40 sccm, 60 sccm, 80 sccm, and 100 sccm.

[0093] It can be understood that during the execution of step 140, introducing the inert gas into the reaction chamber synchronously can maintain the pressure in the reaction chamber.

[0094] In this application, optionally, after step 140, that is, after introducing the silane precursor into the reaction chamber, an inert gas can also be introduced into the reaction chamber. Among them, when the inert gas is introduced into the reaction chamber, the flow rate of the inert gas is 10 to 200 sccm.

[0095] Specifically, an inert gas can be introduced into the reaction chamber to purge the reaction chamber. Among them, when purging the reaction chamber, the purging time is 3 to 120 s, and the pressure in the reaction chamber is maintained at 0.1 to 2 Torr.

[0096] Furthermore, the purging time is more preferably 5 to 120 s.

[0097] Furthermore, the purging time is most preferably 10 to 100 s.

[0098] It can be understood that after step 140, introducing the inert gas into the reaction chamber can remove the excess silane precursor in the reaction chamber.

[0099] In summary, an optional implementation manner for preparing the molybdenum single crystal thin film in this application includes the following steps 200 to 290:

[0100] Step 200: Pretreat the semiconductor substrate to remove impurities on the surface of the semiconductor substrate.

[0101] Step 210: Place the semiconductor substrate in the reaction chamber of the atomic layer deposition equipment, and the reaction chamber meets preset conditions.

[0102] Step 220: Introduce an inert gas into the reaction chamber.

[0103] Step 230: Introduce a gaseous molybdenum precursor into the reaction chamber to adsorb the molybdenum precursor on the surface of the semiconductor substrate.

[0104] Step 240: Introduce an inert gas into the reaction chamber to purge the reaction chamber.

[0105] Step 250: Introduce a gaseous silane precursor into the reaction chamber to form a molybdenum single crystal thin film on the surface of the semiconductor substrate through a chemical reaction between the silane precursor and the molybdenum precursor, and introduce an inert gas into the reaction chamber during the process of introducing the silane precursor into the reaction chamber.

[0106] Step 260: Introduce an inert gas into the reaction chamber to purge the reaction chamber.

[0107] Step 270: Repeat the above steps 220 to 260 until a molybdenum single crystal thin film with a set thickness is formed on the surface of the semiconductor substrate.

[0108] In the above embodiment, the inert gas can be one or both of high-purity nitrogen gas and high-purity argon gas.

[0109] For the molybdenum single crystal thin film prepared by some implementation manners of this application, by mass fraction, the elemental content of the Mo single crystal thin film includes 60.3% - 85.6% of Mo element, 1.0% - 3.2% of H element, 3.2% - 14.5% of C element, and 4.5% - 8.5% of O element. The thickness of the molybdenum single crystal thin film is 20 - 200 nm, and the growth rate of the molybdenum single crystal thin film is 5.0 Å - 10.2 Å / cycle.

[0110] It can be seen that based on the technical solution of this application, the impurity content of the prepared molybdenum single crystal thin film is low, the growth rate of the molybdenum single crystal thin film is high, and the thickness of the molybdenum single crystal thin film can be accurately controlled.

[0111] Next, in combination with Figures 2 to 4 the beneficial effects obtained in this application will be elaborated.

[0112] See Figure 2 , which shows a schematic image of a single - crystal molybdenum thin film according to an embodiment of the present application.

[0113] Figure 2 (2) is a semiconductor substrate on which no single - crystal molybdenum thin film is formed. Figure 2 (1), (3), and (4) are single - crystal molybdenum thin films formed on different semiconductor substrates based on the technical solution of the present application.

[0114] It can be seen that the single - crystal molybdenum thin film grown by the technical solution of the present application has no semiconductor substrate selectivity, that is, it has compatibility on different semiconductor substrates.

[0115] See Figure 3 , which shows a schematic diagram of the sheet resistance of a 50 - nm - thick single - crystal tungsten thin film at different growth temperatures at the current stage.

[0116] From Figure 3 it can be seen that the sheet resistance of a 50 - nm - thick single - crystal tungsten thin film at different growth temperatures is above 30.

[0117] In addition, the sheet resistance test data of the single - crystal copper thin film is shown in Table 1 below:

[0118]

[0119] Table 1

[0120] Based on the technical solution of the present application, the sheet resistance test data of a prepared single - crystal molybdenum thin film is shown in Table 2 below:

[0121]

[0122] Table 2

[0123] It can be seen that, compared with the single - crystal copper thin film and the single - crystal tungsten thin film, the resistivity of the single - crystal molybdenum thin film prepared based on the technical solution of the present application is smaller for films of the same thickness, and the single - crystal molybdenum thin film is more suitable as a high - level interconnect material.

[0124] See Figure 4 , which shows a schematic AFM image of a single - crystal molybdenum thin film according to an embodiment of the present application.

[0125] From Figure 4 it can be seen that the surface roughness of a single - crystal molybdenum thin film prepared by the technical solution of the present application is relatively low.

[0126] In the technical solutions provided by some embodiments of the present application, during the process of preparing a molybdenum thin film by atomic layer deposition technology, after placing a semiconductor substrate in a reaction chamber of an atomic layer deposition device that meets preset conditions; by repeatedly performing atomic layer deposition cycles, a molybdenum thin film with a set thickness can be formed on the surface of the semiconductor substrate. Wherein, the atomic layer deposition cycle includes the following steps: introducing a gaseous molybdenum precursor into the reaction chamber to adsorb the molybdenum precursor on the surface of the semiconductor substrate; introducing a gaseous silane precursor into the reaction chamber to chemically react the silane precursor with the molybdenum precursor to form a molybdenum thin film on the surface of the semiconductor substrate. Since the key to the quality of the thin film prepared by atomic layer deposition technology lies in the selection of the precursor, in the technical solution of the present application, at least the following technical effects are achieved:

[0127] First, the molybdenum precursor used has a small steric hindrance and relative molecular mass, and at the same time has characteristics such as high volatility, saturated vapor pressure, thermal stability, and reaction activity. When combined with the selected silane precursor, it has high reaction activity and the reaction has self-limiting properties, enabling the preparation of a molybdenum thin film with advantages such as low roughness, high conformality, and low impurity content in the thin film, thereby improving the application performance of the molybdenum thin film.

[0128] Second, the reaction of the precursor used has self-limiting properties. Only one molybdenum atomic layer can grow in one atomic layer deposition cycle, and the film thickness of the obtained molybdenum thin film is precisely controllable.

[0129] Third, the temperature required for the reaction is low, which can reduce energy consumption and synthesis costs.

[0130] Fourth, the grown molybdenum thin film has no selectivity for the semiconductor substrate, that is, it has compatibility on different semiconductor substrates.

[0131] Fifth, the molybdenum precursor provided in the present application is easy to synthesize, has a low production cost, and low energy consumption required for the reaction, which is beneficial to the large-scale preparation of molybdenum thin films.

[0132] In the specification provided herein, a large number of specific details are described. However, it can be understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures, and technologies are not shown in detail so as not to obscure the understanding of this specification.

[0133] Similarly, it should be understood that, for the purpose of streamlining the present disclosure and assisting in understanding one or more of the various inventive aspects, in the foregoing description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting an intention that the claimed subject matter of the present application requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, the inventive aspects lie in less than all of the features of the single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the present application.

[0134] It should be noted that the above embodiments illustrate rather than limit the present application, and those skilled in the art can design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The use of the words first, second, and third, etc. does not denote any order. These words may be interpreted as names.

Claims

1. A method for preparing a single-element molybdenum thin film, characterized in that, The method includes: Placing a semiconductor substrate in a reaction chamber of an atomic layer deposition apparatus, where the reaction chamber meets preset conditions; Repeatedly performing an atomic layer deposition cycle until a molybdenum thin film with a set thickness is formed on the surface of the semiconductor substrate. Wherein, the atomic layer deposition cycle includes the following steps: Introducing a gaseous molybdenum precursor into the reaction chamber to adsorb the molybdenum precursor on the surface of the semiconductor substrate; Introducing a gaseous silane precursor into the reaction chamber to chemically react the silane precursor with the molybdenum precursor to form a molybdenum thin film on the surface of the semiconductor substrate.

2. The method according to claim 1, wherein The preset conditions include: the reaction chamber is in a vacuum state and the temperature is 100 - 400 °C.

3. The method according to claim 1, wherein The introduction time of the molybdenum precursor is 0.01 - 5 s; the introduction time of the silane precursor is 0.01 - 3 s.

4. The method according to claim 1, wherein The temperature of the molybdenum precursor is 0 - 50 °C; the temperature of the silane precursor is 0 - 50 °C.

5. The method according to claim 1, wherein The semiconductor substrate includes one of single crystal silicon, silicon oxide, silicon nitride, sapphire, and glass; the molybdenum precursor includes one or more of MoCl5, MoO2Cl2, and MoF6.

6. The method according to claim 1, wherein The atomic layer deposition cycle further includes: Before and after introducing the molybdenum precursor or the silane precursor into the reaction chamber, and during the process of introducing the silane precursor into the reaction chamber, an inert gas is introduced into the reaction chamber.

7. The method according to claim 6, characterized in that, When introducing the inert gas into the reaction chamber, the flow rate of the inert gas is 10 - 200 sccm.

8. The method according to claim 7, wherein After introducing the molybdenum precursor into the reaction chamber and before introducing the silane precursor into the reaction chamber, an inert gas is introduced into the reaction chamber to purge the reaction chamber. Wherein, when purging the reaction chamber, the purge time is 1 - 100 s, and the pressure of the reaction chamber is maintained at 0.1 - 2 Torr.

9. The method according to claim 7, characterized in that, After introducing the silane precursor into the reaction chamber, an inert gas is introduced into the reaction chamber to purge the reaction chamber. Wherein, when purging the reaction chamber, the purge time is 3 - 120 s, and the pressure of the reaction chamber is maintained at 0.1 - 2 Torr.

10. The method according to claim 1, characterized in that, Before placing the semiconductor substrate in the reaction chamber of the atomic layer deposition apparatus, the semiconductor substrate is pretreated to remove impurities on the surface of the semiconductor substrate.

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