Preparation method of alpha-phase molybdenum trioxide film, back-gate silicon-based field effect transistor and preparation method thereof

Abstract

The application belongs to the technical field of semiconductor manufacturing, and particularly relates to a preparation method of an alpha-phase molybdenum trioxide film, a back-gate silicon-based field effect transistor and a preparation method thereof. A precursor is dispersed in an organic solvent to obtain a precursor solution, the precursor containing molybdenum elements and sulfur elements; the precursor solution is coated on a substrate surface to obtain a substrate with a precursor wet film; the substrate with the precursor wet film is sequentially heat-treated, subjected to first annealing treatment in a protective gas atmosphere, and subjected to second annealing treatment in an oxidizing atmosphere to obtain an alpha-phase molybdenum trioxide film. The alpha-phase molybdenum trioxide film obtained by the application has the characteristics of high film quality, excellent interface characteristics and high crystal phase purity, can form a high-quality, undamaged interface with a two-dimensional semiconductor channel as a gate dielectric layer material, and can realize ultra-thin EOT, thereby solving the problems of large leakage current and weak gate control capability of the FET in the prior art.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor manufacturing, and particularly relates to a preparation method of an alpha-phase molybdenum trioxide film, a back-gate silicon-based field effect transistor and a preparation method thereof. BACKGROUND

[0002] With the advancement of Moore's law, the feature size of silicon-based field effect transistors (FETs) continues to shrink. In order to suppress the short channel effect and maintain effective gate control, the device architecture has evolved from a planar type to a three-dimensional structure such as a fin field effect transistor (Fin-FET) and a gate-all-around (GAA). When the size of the silicon-based transistor enters the sub-nanometer level, its performance faces physical limits such as a sharp increase in gate leakage current and a significant decrease in gate control ability caused by quantum tunneling effect, which limits the further improvement of device performance. Therefore, developing new gate dielectric layer materials to continue the development of semiconductor technology has become the consensus in the industry.

[0003] Among the many potential gate dielectric layer materials, molybdenum trioxide (MoO3) has received widespread attention due to its unique physical and chemical properties. In terms of material performance, MoO3 has a moderate dielectric constant (usually between 10 and 15), which is significantly higher than the traditional SiO2, and can reduce the risk of leakage current while maintaining a certain EOT. More importantly, MoO3 has an elemental correlation with MoS2 and other molybdenum-based two-dimensional semiconductor materials as the channel layer, and has natural advantages in crystal structure and electronic band matching, which can theoretically form a more stable and low-defect interface, which is crucial for improving gate control ability. In addition, MoO3 also has good thermal stability and chemical stability, which can maintain structural integrity during device preparation and subsequent work, avoiding performance degradation due to material decomposition or reaction. These characteristics make it a potential gate dielectric candidate material that adapts to two-dimensional semiconductor channels.

[0004] In order to effectively regulate the channel, the gate dielectric layer needs to have an equivalent oxide layer thickness (EOT) of less than 1 nanometer and a high-quality interface. In the prior art, molybdenum trioxide is usually grown using atomic layer deposition (ALD) technology. However, due to the lack of chemical reaction sites between the precursors of the ALD process and the inert surface of the two-dimensional material, it is easy to cause uneven nucleation and form defect states during the deposition process, thereby degrading the interface quality between the gate dielectric layer and the channel. Especially when pursuing extremely low EOT, these problems will be more prominent, ultimately leading to a significant increase in gate leakage current, which seriously affects the performance and reliability of the device.

[0005] In summary, MoO3 has significant application potential as a gate dielectric layer material, but the optimization of its deposition technology and the efficient integration with two-dimensional semiconductor channels still face many bottlenecks. Developing a MoO3 deposition method that adapts to the characteristics of two-dimensional materials, and realizing the controllable preparation of high-quality, low-defect MoO3 dielectric layers, has important research value and practical significance for promoting performance breakthroughs in two-dimensional semiconductor transistors. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of alpha-phase molybdenum trioxide film, back-gate silicon-based field effect transistor and its preparation method. The alpha-phase molybdenum trioxide film obtained by the preparation method provided by the present application has the characteristics of high film quality, excellent interface characteristics and high crystal phase purity. As a gate dielectric layer material, it can form a high-quality, damage-free interface with a two-dimensional semiconductor channel and achieve ultra-thin EOT, thereby solving the problems of large leakage current and weak gate control ability of FET in the prior art. At the same time, the preparation method provided by the present application is efficient, low in cost and suitable for large-scale production.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0008] The present application provides a preparation method of alpha-phase molybdenum trioxide film, comprising the following steps:

[0009] The precursor is dispersed in an organic solvent to obtain a precursor solution, wherein the precursor contains molybdenum and sulfur elements;

[0010] The precursor solution is coated on the surface of the substrate to form a precursor wet film, thereby obtaining a substrate with a precursor wet film;

[0011] The substrate with the precursor wet film is subjected to heat treatment to form a precursor thin film, thereby obtaining a substrate with a precursor thin film;

[0012] The substrate with the precursor thin film is subjected to a first annealing treatment in a protective gas atmosphere to form a molybdenum disulfide (MoS2) intermediate phase thin film, thereby obtaining a substrate with a molybdenum disulfide intermediate phase thin film;

[0013] The substrate with the molybdenum disulfide intermediate phase thin film is subjected to a second annealing treatment in an oxidizing atmosphere to obtain an alpha-phase molybdenum trioxide film on the surface of the substrate.

[0014] Preferably, the organic solvent comprises N,N-dimethylformamide, n-butylamine and ethanolamine; the volume ratio of N,N-dimethylformamide, n-butylamine and ethanolamine is (4-6):(1-3):(1-3).

[0015] Preferably, the precursor is ammonium tetrathiomolybdate; the mass concentration of the precursor in the precursor solution is 5-15 mg / mL.

[0016] Preferably, before the coating, the substrate surface is subjected to a hydrophilic treatment, and the hydrophilic treatment comprises plasma treatment and / or ultraviolet ozone treatment.

[0017] Preferably, the coating is spin coating, and the spin coating comprises sequentially performing a first spin coating and a second spin coating, the first spin coating is performed at a rotation speed of 400-600 rpm for 5-15 s; the second spin coating is performed at a rotation speed of 2000-3000 rpm for 20-40 s.

[0018] Preferably, the heat treatment is performed at a temperature of 120-160℃ for 2-5 min.

[0019] Preferably, the first annealing treatment is performed at a temperature of 650-750℃ for 15-30 min; the protective gas atmosphere is nitrogen and / or argon.

[0020] Preferably, the second annealing treatment is performed at a temperature of 350-450℃ for 15-30 min; the oxidizing atmosphere is an atmosphere containing oxygen.

[0021] The application provides a preparation method of a back-gate silicon-based field effect transistor, comprising the following steps:

[0022] A gate dielectric layer is prepared on the surface of the substrate, and the gate dielectric layer is prepared according to the preparation method in the above technical solution;

[0023] A channel layer is prepared on the surface of the gate dielectric layer; and a metal electrode is prepared on the surface of the channel layer.

[0024] The application provides a back-gate silicon-based field effect transistor prepared by the preparation method in the above technical solution.

[0025] The application provides a preparation method of an alpha-phase molybdenum trioxide (alpha-MoO3) film, comprising the following steps: dispersing a precursor in an organic solvent to obtain a precursor solution, wherein the precursor contains molybdenum elements and sulfur elements; coating the precursor solution on a surface of a substrate to form a precursor wet film, thereby obtaining a substrate with the precursor wet film; performing heat treatment on the substrate with the precursor wet film to form a precursor film, thereby obtaining a substrate with the precursor film; performing a first annealing treatment on the substrate with the precursor film in a protective gas atmosphere to form a molybdenum disulfide intermediate-phase film, thereby obtaining a substrate with the molybdenum disulfide intermediate-phase film; and performing a second annealing treatment on the substrate with the molybdenum disulfide intermediate-phase film in an oxidizing atmosphere to obtain an alpha-phase molybdenum trioxide film on the surface of the substrate. The precursor film is first converted into a molybdenum disulfide (MoS2) intermediate-phase film through the first annealing treatment in the protective gas atmosphere, and then the molybdenum disulfide intermediate-phase film is in-situ oxidized into an alpha-MoO3 film through the second annealing treatment in the oxidizing atmosphere. The high-quality alpha-MoO3 film is prepared on the surface of the substrate through the two-step conversion. Compared with the prior art, the application has the following beneficial effects:

[0026] The alpha-phase molybdenum trioxide film prepared by the preparation method has high quality and excellent interface characteristics. In the prior art, the preparation of a high-quality two-dimensional film often adopts a "growth-transfer" method. The transfer process is extremely prone to introduce defects such as wrinkles, damage, pollutants and interface air gaps, thereby seriously deteriorating the interface quality between the film and the substrate and affecting the device performance. The application adopts an in-situ oxidation method, that is, the molybdenum disulfide intermediate phase is directly converted into an alpha-MoO3 film on the final target substrate, thereby completely avoiding the physical transfer step. This ensures that the prepared alpha-MoO3 film and the substrate can form a clean, dense and physically undamaged atomic-level contact interface, thereby obtaining excellent interface characteristics that are difficult to achieve by the existing transfer method.

[0027] The alpha-phase molybdenum trioxide film prepared by the preparation method has high crystal phase purity and controllable crystalline quality. Compared with directly oxidizing the precursor into alpha-MoO3 in one step, the reaction conditions are difficult to accurately control, and amorphous or other impurities are easily generated, resulting in impure phases and poor crystalline quality of the film. The application creatively introduces a MoS2 intermediate phase. Since MoS2 itself is a structured layered material, a high-quality MoS2 film is first formed in the first step of conversion, thereby providing a high-quality "structure template" for the oxidation reaction in the second step. The phase transition process based on the ordered template is more moderate, uniform and controllable, and can effectively inhibit the generation of impurities, thereby ensuring that the final product is a high-purity alpha-phase molybdenum trioxide, and the crystalline quality is significantly improved.

[0028] The preparation method provided by the application has high preparation efficiency, low cost and is suitable for large-scale production. The preparation method provided by the application adopts a low-cost and high-efficiency solution method for preparing a precursor film, without the need for a vacuum environment. The subsequent first annealing treatment (sulfuration conversion) and second annealing treatment (oxidation conversion) steps can be carried out in a tube furnace under normal pressure or low vacuum, and the equipment cost and process complexity are much lower than those of traditional methods such as molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) which require an ultrahigh vacuum environment. Therefore, the overall preparation process of the application is simple, the equipment requirement is low, and the application is easy to expand to large-area and batch production, while ensuring high quality, and has the potential for industrial application with high efficiency and low cost. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A flow chart (cross section) of a back gate FET device based on pyrogenic preparation of molybdenum trioxide medium layer in the embodiment of the application;

[0030] Figure 2 A transfer curve of a back gate molybdenum trioxide thin film field effect transistor prepared in Example 2 of the application;

[0031] Figure 3 A transfer curve (Vds=5V) of a back gate silicon dioxide thin film field effect transistor prepared in Comparative Example 1 of the application;

[0032] Wherein: 1-substrate; 2-precursor solution coating and heat treatment; 3-first annealing treatment and second annealing treatment; 4-transfer of two-dimensional semiconductor material on the surface of the alpha phase molybdenum trioxide thin film; 5-spin coating photoresist; 6-exposure and development; 7-metal electrode preparation; 8-peeling and degumming. DETAILED DESCRIPTION

[0033] The application provides a preparation method of an alpha phase molybdenum trioxide thin film, comprising the following steps:

[0034] The precursor is dispersed in an organic solvent to obtain a precursor solution, wherein the precursor contains molybdenum elements and sulfur elements;

[0035] The precursor solution is coated on the surface of a substrate to form a precursor wet film, thereby obtaining a substrate with a precursor wet film;

[0036] The substrate with the precursor wet film is subjected to heat treatment to form a precursor thin film, thereby obtaining a substrate with a precursor thin film;

[0037] The substrate with the precursor thin film is subjected to first annealing treatment in a protective gas atmosphere to form a molybdenum disulfide (MoS2) intermediate phase thin film, thereby obtaining a substrate with a molybdenum disulfide intermediate phase thin film;

[0038] The substrate with the thin film of the intermediate phase of molybdenum disulfide is subjected to a second annealing treatment in an oxidizing atmosphere, so as to obtain a thin film of α-phase molybdenum trioxide on the surface of the substrate.

[0039] The application provides a method for preparing a thin film of α-phase molybdenum trioxide (α-MoO3) based on a two-step in-situ conversion method.

[0040] The precursor solution is obtained by dispersing a precursor in an organic solvent, wherein the precursor contains molybdenum and sulfur.

[0041] In the application, the organic solvent preferably comprises N,N-dimethylformamide (DMF), n-butylamine and ethanolamine. The volume ratio of the DMF, n-butylamine and ethanolamine is preferably (4-6):(1-3):(1-3), and can be 5:2:1 in the embodiment. The DMF, n-butylamine and ethanolamine are preferably ultrasonically mixed to obtain the organic solvent, and the ultrasonic mixing time is preferably 5-10 min.

[0042] In the application, the precursor can be ammonium tetrathiomolybdate (ATTM). The dispersing is preferably performed by dispersing the precursor in the organic solvent under ultrasonic condition. The dispersing time is preferably 30-35 min. The mass concentration of the precursor in the precursor solution is preferably 5-15 mg / mL, and can be 10 mg / mL in the embodiment.

[0043] The application can avoid uneven wet film or holes of the precursor during coating by optimizing the type and volume ratio of the organic solvent in the precursor solution, and optimizing the mass concentration of the precursor in the precursor solution.

[0044] After obtaining the precursor solution, the precursor solution is coated on the surface of the substrate to form a wet film of the precursor, so as to obtain a substrate with the wet film of the precursor.

[0045] In the application, before the coating, the substrate surface is preferably subjected to a hydrophilic treatment. The hydrophilic treatment preferably comprises plasma treatment and / or ultraviolet ozone treatment. The application does not have special requirements for the specific implementation of the plasma treatment or ultraviolet ozone treatment.

[0046] In the present application, the coating is preferably spin coating. The spin coating preferably comprises sequentially performing a first spin coating and a second spin coating. The rotation speed of the first spin coating is preferably 400-600 rpm, and in an embodiment can be 500 rpm. The time of the first spin coating is preferably 5-15 s, and in an embodiment can be 10 s. The rotation speed of the second spin coating is preferably 2000-3000 rpm, and in an embodiment can be 2500 rpm. The time of the second spin coating is preferably 20-40 s, and in an embodiment can be 30 s.

[0047] After obtaining the substrate with the wet precursor film, the present application performs heat treatment on the substrate with the wet precursor film to form a precursor thin film, thereby obtaining a substrate with the precursor thin film.

[0048] In the present application, the heat treatment is performed on a hot plate. The present application realizes evaporation of the organic solvent in the wet precursor film through the heat treatment, thereby solidifying a uniform precursor thin film.

[0049] In the present application, the temperature of the heat treatment is preferably 120-160℃, and in an embodiment can be 150℃. The time of the heat treatment is preferably 2-5 min, and in an embodiment can be 3 min.

[0050] After obtaining the substrate with the precursor thin film, the present application performs a first annealing treatment on the substrate with the precursor thin film in a protective gas atmosphere to form a molybdenum disulfide (MoS2) intermediate phase thin film, thereby obtaining a substrate with the molybdenum disulfide intermediate phase thin film. In the present application, the molybdenum disulfide (MoS2) intermediate phase thin film is a molybdenum disulfide thin film.

[0051] In the present application, the first annealing treatment is to prepare a multilayer molybdenum disulfide by a pyrolysis method. The first annealing treatment is to perform sulfurization conversion, thereby converting the precursor thin film into a molybdenum disulfide intermediate phase thin film.

[0052] In the present application, the temperature of the first annealing treatment is preferably 650-750℃, and in an embodiment can be 700℃. The time of the first annealing treatment is preferably 15-30 min, and in an embodiment can be 20 min. The protective gas atmosphere is preferably nitrogen and / or argon.

[0053] By controlling the temperature of the first annealing treatment, the present application can ensure that the precursor thin film is completely converted into a molybdenum disulfide intermediate phase, thereby ensuring subsequent conversion. If the temperature of the first annealing treatment is too low, the sulfurization will fail or be incomplete, thereby becoming a non-molybdenum disulfide intermediate phase. By controlling the above parameters of the first annealing treatment, the present application can realize sufficient in-situ conversion of the precursor thin film, thereby obtaining a molybdenum disulfide (MoS2) intermediate phase thin film.

[0054] After obtaining the substrate with the molybdenum disulfide intermediate phase thin film, the present application performs a second annealing treatment on the substrate with the molybdenum disulfide intermediate phase thin film in an oxidizing atmosphere to obtain an α-phase molybdenum trioxide thin film on the surface of the substrate.

[0055] In the present application, the second annealing treatment causes an oxidation conversion to oxidize the molybdenum disulfide intermediate phase thin film into an α-phase molybdenum trioxide thin film.

[0056] In the present application, the temperature of the second annealing treatment is preferably 350-450°C, and can be 400°C in an embodiment. The time of the second annealing treatment is preferably 15-30 min, and can be 20 min in an embodiment. The oxidizing atmosphere is preferably an atmosphere containing oxygen. The atmosphere containing oxygen can be oxygen. The flow rate of the atmosphere containing oxygen is preferably 400-600 sccm, and can be 500 sccm in an embodiment.

[0057] By controlling the above parameters of the second annealing treatment, the present application can cause the molybdenum disulfide intermediate phase thin film to be fully oxidized into the target product α-phase molybdenum trioxide (α-MoO3) thin film in situ.

[0058] The present application provides a preparation method of a back-gate silicon-based field effect transistor, comprising the following steps:

[0059] A gate dielectric layer is prepared on the surface of the substrate, and the gate dielectric layer is prepared according to the preparation method described in the above technical solution;

[0060] A channel layer is prepared on the surface of the gate dielectric layer, and a metal electrode is prepared on the surface of the channel layer.

[0061] The preparation process of the back-gate silicon-based field effect transistor provided by the present application is as shown in Figure 1 In the present application, the substrate can be a silicon-based wafer substrate. The preparation method of the channel layer can be a transfer method. The channel layer is a two-dimensional semiconductor material, and preferably a single-layer two-dimensional semiconductor material. The channel layer is more preferably MoS2, and can be a single-layer MoS2 in an embodiment. The present application preferably grows the two-dimensional semiconductor material by using a CVD method, and then sets the two-dimensional semiconductor material on the surface of the gate dielectric layer to obtain the channel layer. An intermediate product is obtained.

[0062] After the intermediate product is obtained, the intermediate product is coated with a photoresist on the surface of the channel layer, and then sequentially subjected to a patterning process, metal deposition and resist removal to obtain the metal electrode. The metal electrode includes a source electrode and a drain electrode. The photoresist can be a positive photoresist, such as an AZ5214 series photoresist. The patterning process preferably includes: ultraviolet exposure using a mask, then curing on a hot plate, and finally developing in a developer to form a mask of the electrode pattern. The developer can be a TMAH-based developer. The metal deposition can be electron beam evaporation.

[0063] The application provides a back gate silicon-based field effect transistor prepared by the preparation method.

[0064] In order to further illustrate the application, the technical solutions provided by the application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the application.

[0065] Example 1

[0066] The embodiment provides a preparation method of an α-phase molybdenum trioxide film, which specifically includes the following steps.

[0067] (I) Preparation of precursor solution

[0068] 1. An organic solvent is provided, which is mixed by DMF, n-butylamine and ethanolamine in a volume ratio of 5:2:1 in the embodiment, and is ultrasonically treated for 10 min to ensure uniform mixing.

[0069] 2. ATTM is dissolved in the above organic solvent to configure a precursor solution, and the concentration of ATTM in the precursor solution is 10 mg / mL. The ATTM is uniformly dispersed by ultrasonic treatment for 30 min.

[0070] (II) In-situ preparation of α-phase molybdenum trioxide (α-MoO3) film

[0071] 1. Substrate pretreatment and coating: a substrate is provided, which is a four-inch silicon-based wafer substrate in the embodiment. In order to enhance the surface hydrophilicity, the surface of the substrate is subjected to plasma or ultraviolet ozone treatment. Then, the precursor solution prepared in step (I) is uniformly coated on the surface of the substrate by a spin coating method to form a precursor wet film. The spin coating parameters are set as follows: the first rotation speed is 500 rpm, the time is 10 s, the second rotation speed is 2500 rpm, and the time is 30 s.

[0072] 2. Solidification and solvent evaporation: The substrate with the precursor wet film was subjected to heat treatment, in this embodiment, heated on a hot plate at 150 °C for 3 min, to solidify the precursor wet film and remove the residual organic solvent, forming a uniform precursor thin film.

[0073] 3. First step conversion (sulfuration): The substrate with the precursor thin film was placed in a heat treatment device (rapid thermal annealing furnace) and subjected to a first annealing treatment at a first preset temperature (700 °C) for 20 min in an inert atmosphere (nitrogen or argon), to convert the precursor thin film in situ into a molybdenum disulfide (MoS2) intermediate phase thin film.

[0074] 4. Second step conversion (oxidation): The substrate with the molybdenum disulfide intermediate phase thin film was subjected to a second annealing treatment at a second preset temperature (400 °C) for 20 min in an oxidizing atmosphere (such as pure oxygen), to fully oxidize the molybdenum disulfide intermediate phase thin film in situ into the target product, an α-phase molybdenum trioxide (a-MoO3) thin film. The a-MoO3 thin film prepared in this embodiment has high quality, excellent interface characteristics, and high phase purity.

[0075] Example 2

[0076] To verify that the a-MoO3 thin film prepared by the above method can be used as a high-performance gate dielectric layer, a back-gate silicon-based field effect transistor was further prepared in this embodiment, specifically including the following steps:

[0077] 1. Channel layer preparation: A two-dimensional semiconductor material (such as a single-layer MoS2 grown by CVD) was used as a channel layer and covered on the a-MoO3 thin film prepared in Example 1 by transfer method.

[0078] 2. Electrode patterning: A standard photolithography and metal deposition process was used to prepare a source electrode and a drain electrode on the channel layer. Specifically, a positive photoresist (AZ5214 series) was spin-coated, ultraviolet exposure was performed through a mask, and after solidification on a hot plate, the photoresist was developed in a developer (TMAH-based developer) to form a mask of electrode patterns. Then, metal was deposited by electron beam evaporation, and finally, the device was formed by peeling.

[0079] In this embodiment, a field effect transistor was constructed using the a-phase molybdenum trioxide thin film prepared in Example 1 to verify its performance.

[0080] Figure 2 The transfer curve of the back-gate a-phase molybdenum trioxide thin film field effect transistor prepared in Example 2 was obtained, and the thickness of the molybdenum trioxide thin film was about 5 nm. Figure 2 The on-off ratio of the device was approximately 10 4 , the threshold voltage was about -1 V, the saturation current was about 1E-7 A, and the sub-threshold swing was 186 mV / dec.

[0081] Comparative Example 1

[0082] The method is substantially the same as that of Example 2, except that a silicon oxide is prepared on the upper surface of the substrate as a gate dielectric layer, and the preparation method of the silicon dioxide film is atomic layer deposition (ALD).

[0083] The atomic layer deposition experiment of the silicon oxide film uses a typical binary reaction system, and the specific operation process and parameter settings are as follows: a silicon-based substrate with a size of four inches is accurately fixed on the bottom stage of the ALD reaction cavity to ensure that the substrate surface is parallel to the reaction gas flow channel and there is no contact pollution. In the experiment, bis(diethylamino)silane (BDEAS, purity ≥ 99.99%) is selected as a silicon source precursor, and the evaporation temperature is controlled at 55°C to ensure a stable vapor pressure; high-purity ozone (O3, concentration ≥ 80 g / m 3 ) is used as an oxygen donor for oxidation reaction and an impurity scavenger. In the deposition process, the single ventilation time of the silicon source and the oxygen source is set to 8 s, and the main body heating temperature of the reaction cavity is maintained at 300°C. By adjusting the ALD cycle number, a silicon oxide film with a thickness of about 280 nm is finally deposited on the surface of the silicon-based substrate. A back gate silicon dioxide film field effect transistor is obtained. Figure 3 The transfer curve of the back gate silicon dioxide film field effect transistor prepared in Comparative Example 1, Figure 3 The on-off ratio thereof is about 10 5 , the threshold voltage is about -30V, the saturation current is about 1E-5A, and the sub-threshold swing is 7.3V / dec, indicating a weak gate control ability.

[0084] From the data of Figure 2 and Figure 3 , it can be seen that the gate control ability of the FET prepared in Example 2 is improved compared with the silicon oxide film field effect transistor prepared in Comparative Example 1.

[0085] From the above examples, it can be seen that the present application prepares high-quality α-phase molybdenum trioxide film by a two-step conversion method of first converting the molybdenum-containing precursor film into a molybdenum disulfide (MoS2) intermediate phase, and then in-situ oxidizing the intermediate phase into α-MoO3. The α-phase molybdenum trioxide film prepared by the present application has the advantages of high film quality, excellent interface characteristics, high crystal phase purity, high preparation efficiency, low cost, and suitability for large-scale production. The α-phase molybdenum trioxide film prepared by the present application has a high dielectric constant (k) as an ultra-thin gate dielectric layer, can form a high-quality, damage-free interface with a two-dimensional semiconductor channel, and realize ultra-thin EOT, thereby solving the problems of large leakage current and weak gate control ability in the prior art.

[0086] Although the above embodiments have been described in detail, it should be understood that these are only some embodiments of the present application, but not all embodiments, and other embodiments can be obtained without creativity on the basis of the above embodiments, and these embodiments all belong to the protection scope of the present application.

Claims

1. A method for fabricating a back-gate silicon-based field-effect transistor, characterized in that, Includes the following steps: A gate dielectric layer is prepared on the surface of a substrate, wherein the gate dielectric layer is prepared according to the following method: The precursor is dispersed in an organic solvent to obtain a precursor solution, wherein the precursor contains molybdenum and sulfur. The precursor solution is coated onto the substrate surface to form a precursor wet film, thereby obtaining a substrate with the precursor wet film. The substrate with the precursor wet film is heat-treated to form a precursor thin film, thereby obtaining a substrate with the precursor thin film. The substrate with the precursor film is subjected to a first annealing treatment in a protective gas atmosphere to form a molybdenum disulfide mesophase film, thereby obtaining a substrate with a molybdenum disulfide mesophase film. The temperature of the first annealing treatment is 650~750℃ and the time is 15~30 min. The protective gas atmosphere is nitrogen and / or argon. The substrate with the molybdenum disulfide mesophase film is subjected to a second annealing treatment in an oxidizing atmosphere to obtain an α-phase molybdenum trioxide film on the substrate surface. The temperature of the second annealing treatment is 350~450℃ and the time is 15~30 min. The oxidizing atmosphere is an atmosphere containing oxygen. A channel layer is prepared on the surface of the gate dielectric layer; a metal electrode is prepared on the surface of the channel layer.

2. The preparation method according to claim 1, characterized in that, The organic solvent includes N,N-dimethylformamide, n-butylamine and ethanolamine; the volume ratio of N,N-dimethylformamide, n-butylamine and ethanolamine is (4~6):(1~3):(1~3).

3. The preparation method according to claim 1 or 2, characterized in that, The precursor is ammonium tetrathiomolybdate; the mass concentration of the precursor in the precursor solution is 5~15 mg / mL.

4. The preparation method according to claim 1, characterized in that, Prior to the coating, the substrate surface is subjected to a hydrophilic treatment, which includes plasma treatment and / or ultraviolet ozone treatment.

5. The preparation method according to claim 1 or 4, characterized in that, The coating is spin coating, which includes performing a first spin coating and a second spin coating in sequence. The first spin coating has a rotation speed of 400~600 rpm and a time of 5~15 s; the second spin coating has a rotation speed of 2000~3000 rpm and a time of 20~40 s.

6. The preparation method according to claim 1, characterized in that, The heat treatment is performed at a temperature of 120~160℃ for 2~5 minutes.

7. A back-gate silicon-based field-effect transistor prepared by the preparation method according to claim 1.

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