Silicon-doped hafnium oxide film and preparation method thereof

Abstract

The invention discloses a silicon-doped hafnium oxide thin film and a preparation method thereof, and belongs to the field of thin film material preparation. The preparation method comprises the following steps: putting a weighed powder precursor into a precursor tank; placing the monocrystalline silicon substrate in a chemical vapor deposition device, vacuumizing and heating; wherein the target temperature of the raw material tank is 200-250 DEG C, the target temperature of the substrate is 810-1100 DEG C, and the raw material tank and the substrate reach the target temperature within the same time; when the temperature is about to reach the target temperature, precursor steam is conveyed to the surface of the monocrystalline silicon substrate through carrier gas, reaction gas and diluent gas are introduced, the deposition pressure is adjusted, and reaction is started; the silicon-doped hafnium oxide film is obtained after the reaction is finished, and the silicon-doped hafnium oxide film contains tetragonal phase hafnium oxide. According to the method, the silicon doping amount of the hafnium oxide thin film can be stably regulated and controlled, so that the content of the tetragonal phase is regulated and controlled, the obtained thin film is continuous and uniform in structure and controllable in thickness, and a simple and efficient means is provided for preparing the tetragonal-phase hafnium oxide thin film through a chemical vapor deposition method.

Description

Technical Field

[0001] The invention belongs to the field of thin film material preparation, and in particular relates to a silicon-doped hafnium dioxide thin film and a preparation method thereof. Background Art

[0002] Compared with lithium-ion batteries or fuel cells, the typical characteristics of electrostatic capacitors are that they are easy to miniaturize, have extremely high power density and fast charging and discharging performance, which makes them a very promising material for energy storage devices in certain specific fields (such as pulse power supplies). There are three types of dielectric materials for electrostatic capacitors: linear dielectric materials, ferroelectric materials and antiferroelectric materials. Referring to the energy loss or energy storage efficiency of linear dielectrics, ferroelectrics and antiferroelectric materials, antiferroelectrics with thin hysteresis loops are more suitable as dielectric materials for energy storage capacitors.

[0003] The stable crystal structure of hafnium dioxide at room temperature and pressure is a monoclinic phase. At standard atmospheric pressure, when the temperature rises to 1770°C, the monoclinic phase (m) will transform into a tetragonal phase (t). The tetragonal phase of hafnium dioxide has antiferroelectric properties and is suitable for use as a dielectric material for energy storage capacitors. Therefore, stabilizing the tetragonal phase that is stable at high temperatures at room temperature and achieving antiferroelectricity is of great significance to scientific research and industrial applications.

[0004] The method reported so far to stabilize the tetragonal phase is mainly element doping, which is the most common and effective means to stabilize the tetragonal phase. The methods for preparing doped hafnium dioxide mainly include atomic layer deposition and pulsed laser deposition. The atomic layer deposition method requires the use of chemical adsorption to cause silicon atoms and hafnium atoms to react layer by layer on the substrate. After several cycles, a homogeneous thin film with highly consistent composition can be obtained, but the deposition rate is too low to grow a thick film. The most important thing is that the film after atomic layer deposition is amorphous, and an annealing process needs to be introduced for crystallization, and titanium nitride double electrodes need to be deposited to stabilize the tetragonal phase, which can easily cause film contamination, resulting in a decrease in film performance. When pulsed laser deposition is used to prepare silicon-doped hafnium dioxide, silicon powder and hafnium dioxide powder need to be sintered into blocks at high temperatures and then installed into a deposition system as a target material. During the deposition process, the doping amount in the target material is a fixed value and cannot be adjusted. Therefore, before preparing hafnium dioxide films with different silicon doping amounts, targets with different doped silicon concentrations need to be re-sintered. The doping concentration cannot be directly adjusted, and is not suitable for large-scale production.

[0005] Chemical vapor deposition technology is a method of using one or more gaseous compounds or single substances containing thin film elements to chemically react on the surface of a substrate to generate a thin film. Chemical vapor deposition technology has the advantages of a large deposition area, a high deposition rate, easy regulation of film components, and can be deposited on the surface of devices with complex shapes. However, the preparation of doped hafnium dioxide thin films often requires the use of two precursors. The two precursors have different diffusion processes on the substrate surface and cannot be effectively diffused on the substrate surface at the same time, making it difficult to ensure that the ratio of the precursors is consistent with the stoichiometric ratio of the product. In addition, the design of a volatilization device for the two precursors greatly increases the complexity of the equipment and the operability of the process. Therefore, the study of the single precursor chemical vapor deposition method to grow silicon-doped hafnium dioxide thin films has important scientific significance and broad application prospects. Summary of the invention

[0006] The main purpose of the present invention is to provide a silicon-doped hafnium dioxide film and a preparation method thereof in view of the deficiencies in the prior art. The method can stably regulate the doping amount of the hafnium dioxide film, thereby regulating the content of the tetragonal phase. The obtained film structure is continuous and uniform, and the thickness is controllable, providing a simple and efficient means for preparing tetragonal hafnium dioxide films by chemical vapor deposition.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for preparing a silicon-doped hafnium dioxide film is provided, comprising the following steps:

[0009] 1) Put the weighed powder precursor in the precursor tank; put the single crystal silicon substrate in the chemical vapor deposition device, evacuate to below 10Pa, and start heating the precursor tank and the single crystal silicon substrate at the same time; wherein: the target temperature of the raw material tank heating is 200-250°C, the target temperature of the substrate heating is 810-1100°C, and the precursor tank and the single crystal silicon substrate reach the target temperature at the same time;

[0010] 2) 50-70 seconds before reaching the target temperature, the precursor vapor in the precursor tank is transported to the surface of the single crystal silicon substrate in the deposition device by a carrier gas, and the reaction gas and the dilution gas are introduced, and the deposition pressure is adjusted to set the deposition time to start the reaction; wherein, the carrier gas flow rate is 25-200 sccm, and the reaction gas flow rate is 10-20 sccm; when the reaction is completed, a silicon-doped hafnium dioxide film is obtained, which contains tetragonal hafnium dioxide.

[0011] According to the above scheme, in step 1), a hot wall horizontal chemical vapor deposition device is used.

[0012] According to the above scheme, in step 1), the gas outlet nozzle of the precursor tank and the single crystal silicon substrate are maintained on the same horizontal plane, with a distance of 5-9 cm.

[0013] According to the above scheme, in step 1), the heating rate of the raw material tank is 3-6°C / min; the heating rate of the substrate is 15-20°C / min, preferably 18-20°C / min.

[0014] According to the above scheme, in step 1), the precursor is hafnium acetylacetonate powder (97%).

[0015] According to the above scheme, in step 1), the single crystal silicon substrate is a (100) oriented silicon single crystal substrate, which is single-sided polished.

[0016] According to the above scheme, in step 1), the single crystal silicon substrate is ultrasonically cleaned by isopropanol, ethanol and ultrapure water. Preferably, ultrasonic cleaning is performed for 8-12 minutes respectively. Isopropanol can effectively dissolve grease and other organic substances, accelerating the cleaning effect. Ethanol can dissolve isopropanol and remove isopropanol remaining on the substrate. Ultrapure water can wash away ethanol. Ultrasonic cleaning makes the cleaning more thorough, ensuring the cleanliness of the growth environment of the hafnium dioxide film on the substrate.

[0017] According to the above scheme, in step 2), the carrier gas is Ar; the reaction gas is O 2 .

[0018] According to the above scheme, in step 2), the diluent gas is Ar, and the flow rate is 50-500 sccm;

[0019] According to the above scheme, in step 2), the deposition pressure is 100-500 Pa.

[0020] According to the above scheme, in step 2), the deposition time is 5-10 minutes.

[0021] A silicon-doped hafnium dioxide film prepared by the above preparation method is provided.

[0022] According to the above scheme, the silicon doping amount is ≤50%.

[0023] According to the above scheme, when the silicon doping amount is 50%, hafnium dioxide is a pure tetragonal phase.

[0024] The present invention provides a method for preparing a silicon-doped hafnium dioxide film, wherein a single crystal silicon substrate is placed in a chemical vapor deposition device, and a separate precursor tank is provided outside the deposition device. The present invention does not separately set a silicon source, but only uses silicon atoms in the silicon substrate as a silicon source. The silicon atoms in the silicon substrate can diffuse under high temperature (>800°C) and low pressure (<1000Pa) conditions and diffuse to the surface of the silicon substrate. By equipping a separate precursor tank outside the deposition device and transporting the precursor gas to the surface of the single crystal silicon substrate through a carrier, the volatilization of the precursor can be better controlled; then, the atmosphere conditions of high carrier gas and low reaction gas are used to dilute the precursor and reduce the reaction rate, so that the hafnium atoms and silicon atoms are uniformly mixed on the surface of the silicon substrate, so as to achieve the purpose of uniform doping, and avoid hafnium atoms directly generating hafnium dioxide on the surface of the silicon substrate, thereby inhibiting the diffusion and doping of silicon atoms.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The present invention provides a method for preparing a silicon-doped hafnium dioxide film, which adopts a chemical vapor deposition method, uses a single crystal silicon substrate itself as a silicon source, and is equipped with a separate precursor tank outside a deposition device. An atmosphere condition of high carrier gas and low reaction gas is adopted, and the volatilization rate and concentration of the precursor atmosphere are strictly controlled to make it uniformly mixed with silicon atoms diffused under high temperature and low pressure conditions in the single crystal silicon substrate, thereby achieving uniform diffusion of silicon in the hafnium dioxide film. The method is simple to operate, has a controllable deposition rate, is low in cost, has good repeatability, and the obtained film has uniform thickness and uniform components, and has important application prospects.

[0027] 2. The present invention does not require an external silicon source precursor, but only needs to use a single hafnium source precursor, and the byproducts of the hafnium source precursor are all gaseous, which will not cause pollution to the film layer under low pressure conditions, and the obtained silicon-doped hafnium dioxide film has high purity.

[0028] 3. Furthermore, by utilizing the property that the diffusion rate of silicon in the substrate increases with increasing temperature, 0-50% silicon-doped hafnium dioxide films can be accurately prepared by changing the deposition temperature to regulate the content of tetragonal hafnium dioxide in the film; at the same time, the film thickness can be controlled by adjusting the precursor volatilization temperature and the dilution gas flow rate to achieve controllable growth of the hafnium dioxide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The XRD spectra of the hafnium dioxide thin films obtained in Examples 1-4 of the present invention and Comparative Example 1. (a) is the XRD spectra of the hafnium dioxide thin film obtained in Example 1 when the silicon doping amount is 50%, (b) and (c) are the XRD spectra of the hafnium dioxide thin films obtained in Examples 2 and 3 when the silicon doping amount is 26% and 20%, (d) is the undoped hafnium dioxide thin film obtained in Comparative Example 1, and (e) is the 130nm hafnium dioxide thin film obtained in Example 4 with a silicon doping amount of 50%.

[0030] Figure 2 Surface and cross-sectional SEM images of the hafnium dioxide thin films obtained in Examples 1-4 of the present invention and Comparative Example 1, wherein (a) and (d) are surface and cross-sectional SEM images of the hafnium dioxide thin film obtained in Example 1 with a silicon doping amount of 50%, respectively; (b) and (e) are surface and cross-sectional SEM images of the hafnium dioxide thin film obtained in Example 2 with a silicon doping amount of 26%, respectively; (c) and (f) are surface and cross-sectional SEM images of the hafnium dioxide thin film obtained in Example 3 with a silicon doping amount of 20%, respectively; (a1) and (d1) are surface and cross-sectional SEM images of the undoped hafnium dioxide thin film obtained in Comparative Example 1, respectively; (a2) and (d2) are surface and cross-sectional SEM images of the 130nm hafnium dioxide thin film obtained in Example 4 with a silicon doping amount of 50%, respectively.

[0031] Figure 3 The XPS spectra of the hafnium dioxide thin film obtained in Examples 1-4 of the present invention and Comparative Example 1. (a) and (d) are XPS spectra of hafnium and oxygen in the hafnium dioxide thin film obtained in Example 1 when the silicon doping amount is 50%, (b) and (e) are XPS spectra of hafnium and oxygen in the hafnium dioxide thin film obtained in Example 2 when the silicon doping amount is 26%, (c) and (f) are XPS spectra of hafnium and oxygen in the hafnium dioxide thin film obtained in Example 3 when the silicon doping amount is 20%, (a1) and (d1) are XPS spectra of hafnium and oxygen in the undoped hafnium dioxide thin film obtained in Comparative Example 1, (a2) and (d2) are XPS spectra of hafnium and oxygen in the 130nm hafnium dioxide thin film obtained in Example 4 when the silicon doping amount is 50%.

[0032] Figure 4 Schematic diagram of the reaction device of the embodiment of the present invention.

[0033] Figure 5 This is a graph showing the relationship between temperature change and the concentration of silicon diffusion in a silicon crystal substrate. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0035] Example 1

[0036] The present invention provides a method for preparing a silicon-doped hafnium dioxide thin film, which comprises the following steps:

[0037] 1) Cutting area is 1×1cm 2The (100) single crystal silicon wafer is ultrasonically cleaned for 10 minutes using isopropyl alcohol (purity of 99.5wt%), ethanol (concentration of 99.5wt%) and ultrapure water in sequence;

[0038] 2) Weigh 0.2g of hafnium acetylacetonate powder on a balance and load it into a precursor tank; use a hot wall horizontal chemical vapor deposition device, place the cleaned single crystal silicon substrate on an alumina porcelain boat, and then place the porcelain boat into a quartz tube in the deposition temperature zone of the deposition device, and the outlet nozzle of the precursor tank is 5cm away from the single crystal silicon substrate; close the flange at the cavity outlet, turn on the vacuum pump and evacuate to 7Pa;

[0039] 3) Set the heating procedures of the precursor tank temperature zone and the deposition temperature zone in the chemical vapor deposition device respectively. The precursor tank temperature zone is heated to the target temperature of 200°C at a rate of 3.64°C / min, and the deposition temperature zone is heated to the target temperature of 1100°C at a rate of 20°C / min. Control the two temperature zones to reach the target temperature at the same time. 60s before reaching the target temperature, open the needle valve between the precursor tank temperature zone and the deposition temperature zone, and transport the precursor vapor in the precursor tank to the surface of the single crystal silicon substrate in the deposition device with a carrier gas, and introduce the reaction gas and dilution gas into the deposition device. Adjust the baffle valve to make the chamber pressure reach 100Pa, where the carrier gas is Ar, the inlet flow rate is 50sccm, and the reaction gas is O 2 , the flow rate is 20sccm, the dilution gas is Ar, and the flow rate is 500sccm; after the two temperature zones reach the target temperature, the program automatically starts timing, and the heating stops after maintaining the target temperature for 7 minutes;

[0040] 4) Stop ventilation, adjust the baffle valve to pump the chamber pressure to 7 Pa again, and cool the deposition device naturally at room temperature to obtain a 40 nm hafnium dioxide film with a silicon doping content of 50%.

[0041] Example 2

[0042] The present invention provides a method for preparing a silicon-doped hafnium dioxide thin film, which comprises the following steps:

[0043] 1) Cutting area is 1×1cm 2 The (100) single crystal silicon wafer is ultrasonically cleaned for 10 minutes using isopropyl alcohol (purity of 99.5wt%), ethanol (concentration of 99.5wt%) and ultrapure water in sequence;

[0044] 2) Weigh 0.2g of hafnium acetylacetonate powder on a balance and put it into the precursor tank; use a hot wall horizontal chemical vapor deposition device, place the cleaned single crystal silicon substrate on an alumina porcelain boat, and then put the porcelain boat into a quartz tube in the deposition temperature zone of the deposition device, and keep the outlet nozzle of the precursor tank 8cm away from the single crystal silicon substrate. Close the flange at the cavity outlet, turn on the vacuum pump and evacuate to 7Pa;

[0045] 3) Set the heating procedures of the precursor tank temperature zone and the deposition temperature zone in the chemical vapor deposition device respectively. The precursor tank temperature zone is heated to the target temperature of 220°C at a rate of 4.4°C / min, and the deposition temperature zone is heated to the target temperature of 1000°C at a rate of 20°C / min. Control the two temperature zones to reach the target temperature at the same time. 65s before reaching the target temperature, open the needle valve between the precursor tank temperature zone and the deposition temperature zone, and transport the precursor vapor in the precursor tank to the surface of the single crystal silicon substrate in the deposition device with a carrier gas, and introduce the reaction gas and dilution gas into the deposition device. Adjust the baffle valve to make the chamber pressure reach 200Pa, where the carrier gas is Ar, the inlet flow rate is 50sccm, and the reaction gas is O 2 , the flow rate is 10sccm, the diluent is Ar, and the flow rate is 400sccm; after the two temperature zones reach the target temperature, the program automatically starts timing, maintains the target temperature for 5 minutes, and then stops heating;

[0046] 4) The ventilation is stopped, and the baffle valve is adjusted to pump the chamber pressure to 7 Pa again. The deposition device is cooled naturally at room temperature to obtain a 40 nm hafnium dioxide film with a silicon doping amount of 29%.

[0047] Example 3

[0048] The present invention provides a method for preparing a silicon-doped hafnium dioxide thin film, which comprises the following steps:

[0049] 1) Cutting area is 1×1cm 2 The (100) single crystal silicon wafer is ultrasonically cleaned for 10 minutes using isopropyl alcohol (purity of 99.5wt%), ethanol (concentration of 99.5wt%) and ultrapure water in sequence;

[0050] 2) Weigh 0.2g of hafnium acetylacetonate powder on a balance and put it into the precursor tank; use a hot wall horizontal chemical vapor deposition device, place the cleaned single crystal silicon substrate on an alumina porcelain boat, and then put the porcelain boat into the quartz tube in the deposition device, with the outlet nozzle of the precursor tank 6cm away from the single crystal silicon substrate. Close the flange at the cavity outlet, turn on the vacuum pump and evacuate to 7Pa;

[0051] 3) Set the heating program of the precursor tank temperature zone and the deposition temperature zone in the chemical vapor deposition device respectively. The precursor tank temperature zone is heated to the target temperature of 220°C at a rate of 4.89°C / min, and the deposition temperature zone is heated to the target temperature of 900°C at a rate of 20°C / min. Control the two temperature zones to reach the target temperature at the same time. 58s before reaching the target temperature, open the needle valve between the precursor tank temperature zone and the deposition temperature zone, and transport the precursor vapor in the precursor tank to the surface of the single crystal silicon substrate in the deposition device with a carrier gas, and introduce the reaction gas and dilution gas into the deposition device. Adjust the baffle valve to make the chamber pressure reach 400Pa, where the carrier gas is Ar, the inlet flow rate is 50sccm, and the reaction gas is O 2 , the flow rate is 10sccm, the dilution gas is Ar, and the flow rate is 300sccm; after the two temperature zones reach the target temperature, the program automatically starts timing, maintains the target temperature for 5 minutes, and then stops heating;

[0052] 4) The ventilation is stopped, and the baffle valve is adjusted to pump the chamber pressure to 7 Pa again. The deposition device is cooled naturally at room temperature to obtain a 40 nm hafnium dioxide film with a silicon doping amount of 17%.

[0053] Comparative Example 1

[0054] The specific operation is the same as that of Example 1, except that the target temperature of the deposition temperature zone is 800° C., and silicon-free hafnium dioxide is obtained. The following steps are included:

[0055] 1) Cutting area is 1×1cm 2 The (100) single crystal silicon wafer is ultrasonically cleaned for 10 minutes using isopropyl alcohol (purity of 99.5wt%), ethanol (concentration of 99.5wt%) and ultrapure water in sequence;

[0056] 2) Weigh 0.2g of hafnium acetylacetonate powder on a balance and put it into the precursor tank; use a hot wall horizontal chemical vapor deposition device, place the cleaned single crystal silicon substrate on an alumina porcelain boat, and then put the porcelain boat into the quartz tube in the deposition device, with the outlet nozzle of the precursor tank 8cm away from the single crystal silicon substrate. Close the flange at the cavity outlet, turn on the vacuum pump and evacuate to 7Pa;

[0057] 3) Set the heating procedures of the precursor tank temperature zone and the deposition temperature zone in the chemical vapor deposition device respectively. The precursor tank temperature zone is heated to the target temperature of 200°C at a rate of 5°C / min, and the deposition temperature zone is heated to the target temperature of 800°C at a rate of 20°C / min. Control the two temperature zones to reach the target temperature at the same time. 55s before reaching the target temperature, open the needle valve between the precursor tank temperature zone and the deposition temperature zone, and transport the precursor vapor in the precursor tank to the surface of the single crystal silicon substrate in the deposition device with a carrier gas, and introduce the reaction gas and dilution gas into the deposition device. Adjust the baffle valve to make the chamber pressure reach 400Pa, where the carrier gas is Ar, the inlet flow rate is 50sccm, and the reaction gas is O 2 , the flow rate is 20sccm, the diluent is Ar, and the flow rate is 500sccm; after the two temperature zones reach the target temperature, the program automatically starts timing, and the heating is stopped after maintaining the target temperature for 8 minutes;

[0058] 2) The ventilation was stopped, and the baffle valve was adjusted to pump the chamber pressure to 7 Pa again. The deposition device was cooled naturally at room temperature to obtain the 40 nm undoped hafnium dioxide film.

[0059] Example 4

[0060] The present invention provides a method for preparing a silicon-doped hafnium dioxide thin film, which comprises the following steps:

[0061] 1) Cutting area is 1×1cm 2 The (100) single crystal silicon wafer is ultrasonically cleaned for 10 minutes using isopropyl alcohol (purity of 99.5wt%), ethanol (concentration of 99.5wt%) and ultrapure water in sequence;

[0062] 2) Weigh 0.2g of hafnium acetylacetonate powder on a balance and put it into the precursor tank; use a hot wall horizontal chemical vapor deposition device, place the cleaned single crystal silicon substrate on an alumina porcelain boat, and then put the porcelain boat into a quartz tube in the deposition temperature zone of the deposition device, and keep the outlet nozzle of the precursor tank 5cm away from the single crystal silicon substrate. Close the flange at the cavity outlet, turn on the vacuum pump and evacuate to 7Pa;

[0063] 3) Set the heating program of the precursor tank temperature zone and the deposition temperature zone in the chemical vapor deposition device respectively. The precursor tank temperature zone is heated to the target temperature of 240°C at a rate of 4.36°C / min, and the deposition temperature zone is heated to the target temperature of 1100°C at a rate of 20°C / min. Control the two temperature zones to reach the target temperature at the same time. 60s before reaching the target temperature, open the needle valve between the precursor tank temperature zone and the deposition temperature zone, and transport the precursor vapor in the precursor tank to the surface of the single crystal silicon substrate in the deposition device with a carrier gas, and introduce the reaction gas and dilution gas into the deposition device. Adjust the baffle valve to make the chamber pressure reach 100Pa, where the carrier gas is Ar, the inlet flow rate is 100sccm, and the reaction gas is O2 , the flow rate is 10sccm, the dilution gas is Ar, and the flow rate is 50sccm; after the two temperature zones reach the target temperature, the program automatically starts timing, and the heating stops after maintaining the target temperature for 9 minutes;

[0064] 4) Stop ventilation, adjust the baffle valve to pump the chamber pressure to 7 Pa again, and cool the deposition device naturally at room temperature to obtain a 130 nm hafnium dioxide film with a silicon doping content of 50%.

[0065] Figure 1 The XRD patterns of the hafnium dioxide films obtained in Examples 1-4 and Comparative Example 1 of the present invention are shown in FIG. Figure 1 (a) shows that when the silicon doping amount in Example 1 is 50%, the content of tetragonal hafnium dioxide is 100%; Figure 1 (b) shows that when the silicon doping amount in Example 2 is 29%, the content of tetragonal hafnium dioxide is 82%; Figure 1 (c) shows that when the silicon doping amount in Example 2 is 17%, the content of tetragonal hafnium dioxide is 54%; Figure 1 (d) shows that when comparative example 1 is not doped with silicon, hafnium dioxide is a pure monoclinic phase; Figure 1 (e) shows that when the silicon doping amount in Example 4 is 50%, the content of tetragonal hafnium dioxide is 100%.

[0066] Figure 2 The surface and cross-sectional SEM images of the hafnium dioxide thin film obtained in comparative example 1 of examples 1-4 of the present invention are shown in FIG. Figure 2 (a) The film surface is granular, the film layer is dense, and the grain size is 5-20nm; Figure 2 (d) shows that the cross section of the film is smooth and the thickness is 40 nm; Figure 2 (b) The film surface is granular, dense, and the grain size is 10-20nm. Figure 2 (e) shows that the cross section of the film is smooth and the thickness is 40 nm; Figure 2 (c) The film surface is granular, dense, and the grain size is 20-30nm. Figure 2 (f) shows that the cross section of the film is smooth and the thickness is 40 nm; Figure 2 (a1) shows that the film surface is granular, the film layer is dense, and the grain size is 5-20nm; Figure 2 (d1) shows that the film cross section is smooth and the thickness is 40nm. Figure 2 (a2) shows that the film surface is granular, the film layer is dense, and the grain size is 60-70nm; Figure 2 (d2) shows that the cross section of the film is smooth and its thickness is 130nm.

[0067] Figure 3 The XPS spectra of the hafnium dioxide films obtained in Examples 1-4 and Comparative Example 1 of the present invention are shown. Figure 3 (a) is the 4f orbital of the Hf element. The 4f7 / 2 and 4f5 / 2 split peaks appear in the figure, and the binding energy is located at 16-18eV, indicating that the Hf element in the product is tetravalent. Figure 3 (d) is the 1s orbital of the O element. Two split peaks, O-Hf and O-Si, appear in the figure, indicating that the film layer is silicon-doped hafnium dioxide. The silicon doping amount is 50% calculated based on the area ratio of the two peaks. Figure 3 (b) is the 4f orbital of the Hf element. The 4f7 / 2 and 4f5 / 2 split peaks appear in the figure, and the binding energy is located at 16-18eV, indicating that the Hf element in the product is tetravalent. Figure 3 (e) is the 1s orbital of the O element. Two split peaks, O-Hf and O-Si, appear in the figure, indicating that the film layer is silicon-doped hafnium dioxide. The silicon doping amount is calculated to be 26% based on the area ratio of the two peaks. Figure 3 (c) is the 4f orbital of the Hf element. The 4f7 / 2 and 4f5 / 2 split peaks appear in the figure, and the binding energy is located at 16-18eV, indicating that the Hf element in the product is tetravalent. Figure 3 (f) is the 1s orbital of the O element. Two split peaks, O-Hf and O-Si, appear in the figure, indicating that the film layer is silicon-doped hafnium dioxide. The silicon doping amount is 20% calculated based on the area ratio of the two peaks. Figure 3 (a1) is the 4f orbital of the Hf element. The 4f7 / 2 and 4f5 / 2 split peaks appear in the figure, and the binding energy is located at 20-24eV, indicating that the Hf element in the product is tetravalent. Figure 3 (d1) is the 1s orbital of the O element. Only two split peaks, O-Hf and OC, appear in the figure, indicating that there is no silicon doping in the film layer; Figure 3 (a2) is the 4f orbital of the Hf element. The 4f7 / 2 and 4f5 / 2 split peaks appear in the figure, and the binding energy is located at 16-18 eV, indicating that the Hf element in the product is tetravalent. Figure 3 (d2) is the 1s orbital of the O element. Two split peaks, O-Hf and O-Si, appear in the figure, indicating that the film layer is silicon-doped hafnium dioxide. The silicon doping amount is calculated to be 50% based on the area ratio of the two peaks.

[0068] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for preparing a silicon-doped hafnium dioxide thin film, characterized in that: The following steps are involved: 1) Put the weighed powder precursor in the precursor tank; put the single crystal silicon substrate in the chemical vapor deposition device, evacuate to below 10Pa, and start heating the precursor tank and the single crystal silicon substrate at the same time; wherein: the target temperature of the raw material tank heating is 200-250°C, the target temperature of the substrate heating is 810-1100°C, and the precursor tank and the single crystal silicon substrate reach the target temperature at the same time; 2) 50-70 seconds before reaching the target temperature, the precursor vapor in the precursor tank is transported to the surface of the single crystal silicon substrate in the deposition device by a carrier gas, and the reaction gas and dilution gas are introduced, and the deposition pressure is adjusted to set the deposition time to start the reaction; wherein, the carrier gas flow rate is 25-200 sccm, and the reaction gas flow rate is 10-20 sccm; when the reaction is completed, a silicon-doped hafnium dioxide film is obtained, which contains tetragonal hafnium dioxide.

2. The preparation method according to claim 1, characterized in that: In the step 1), the gas outlet nozzle of the precursor tank and the single crystal silicon substrate are kept on the same horizontal plane, with a distance of 5-9 cm.

3. The preparation method according to claim 1, characterized in that: In the step 1), the heating rate of the raw material tank is 3-6°C / min; the heating rate of the substrate is 15-20°C / min.

4. The preparation method according to claim 1, characterized in that: In the step 1), the precursor is hafnium acetylacetonate powder.

5. The preparation method according to claim 1, characterized in that: In the step 1), the single crystal silicon substrate is a (100) oriented silicon single crystal substrate, which is single-sided polished.

6. The preparation method according to claim 1, characterized in that: In the step 2), the carrier gas is Ar; the reaction gas is O2; the dilution gas is Ar, and the flow rate is 50-500 sccm.

7. The preparation method according to claim 1, characterized in that: In the step 2), the deposition pressure is 100-500 Pa.

8. The preparation method according to claim 1, characterized in that: In the step 2), the deposition time is 5-10 minutes.

9. A silicon-doped hafnium dioxide thin film prepared by the preparation method according to any one of claims 1 to 8.

10. The hafnium dioxide thin film according to claim 9, characterized in that: Silicon doping amount ≤ 50%.

Images