A silicon-doped hafnium dioxide thin film and a method for preparing the same

Abstract

The application discloses a kind of silicon-doped hafnium dioxide thin films and preparation method thereof, belong to the field of thin film material preparation.It is prepared: the powder precursor weighed is placed in precursor tank;Single crystal silicon substrate is placed in chemical vapor deposition device, vacuum and heating;Wherein: the target temperature of raw material tank is 200-250 DEG C, and the target temperature of substrate is 810-1100 DEG C, and both reach target temperature with same time;When reaching target temperature, precursor vapor is transported to the surface of single crystal silicon substrate with carrier gas, and reaction gas and dilution gas are input, and deposition pressure is adjusted, and reaction starts;Reaction is finished, and silicon-doped hafnium dioxide thin film is obtained, and contains tetragonal hafnium dioxide.The method can stably control the silicon doping amount of hafnium dioxide thin film, so as to control the content of tetragonal phase, and the obtained thin film structure is continuous and uniform, and the thickness is controllable, which provides a simple and efficient means for preparing tetragonal hafnium dioxide thin film by chemical vapor deposition method.

Description

Technical Field

[0001] The present 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 to lithium-ion batteries or fuel cells, electrostatic capacitors are characterized by their ease of miniaturization, extremely high power density, and rapid charge and discharge performance, making them highly promising materials for energy storage devices in specific applications, such as pulsed power supplies. There are three types of dielectric materials for electrostatic capacitors: linear dielectrics, ferroelectrics, and antiferroelectrics. Based on the energy loss or energy storage efficiency of linear dielectrics, ferroelectrics, and antiferroelectrics, antiferroelectrics with thin hysteresis loops are more suitable as dielectric materials for energy storage capacitors.

[0003] Hafnium dioxide's stable crystal structure at room temperature and pressure is a monoclinic phase. At standard atmospheric pressure, when the temperature rises to 1770°C, the monoclinic phase (m) transforms into the tetragonal phase (t). The tetragonal phase of hafnium dioxide exhibits antiferroelectric properties, making it suitable as a dielectric material for energy storage capacitors. Therefore, stabilizing the high-temperature, tetragonal phase at room temperature and achieving antiferroelectricity is of great significance to both scientific research and industrial applications.

[0004] Currently reported methods for stabilizing the tetragonal phase are mainly element doping, which is the most common and effective means of stabilizing the tetragonal phase. The main methods for preparing doped hafnium dioxide are 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 fixed 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 controlled, making it unsuitable for large-scale production.

[0005] Chemical vapor deposition technology is a method of generating thin films by chemically reacting one or more gaseous compounds or single substances containing thin film elements on the surface of a substrate. Chemical vapor deposition technology has the advantages of a large deposition area, a high deposition rate, easy control of film composition, 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 effectively diffuse 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, studying the growth of silicon-doped hafnium dioxide thin films by single precursor chemical vapor deposition has important scientific significance and broad application prospects. Summary of the Invention

[0006] The main purpose of the present invention is to address the deficiencies in the prior art and provide a silicon-doped hafnium dioxide film and a method for preparing the same. The method can stably regulate the doping amount of the hafnium dioxide film, thereby regulating the content of the tetragonal phase. The resulting 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 thin film is provided, comprising the following steps:

[0009] 1) Place the weighed powdered precursor in a precursor tank; place the single crystal silicon substrate in a chemical vapor deposition apparatus, evacuate to below 10 Pa, and simultaneously heat the precursor tank and the single crystal silicon substrate; wherein: the target temperature of the raw material tank is 200-250°C, and the target temperature of the substrate 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 using a carrier gas, and the reaction gas and dilution gas are introduced. The deposition pressure is adjusted to a certain level, and the deposition time is set to start the reaction. The carrier gas flow rate is 25-200 sccm, and the reaction gas flow rate is 10-20 sccm. Upon completion of the reaction, a silicon-doped hafnium dioxide thin film containing tetragonal hafnium dioxide is obtained.

[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 kept 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 using isopropyl alcohol, ethanol, and ultrapure water. Preferably, each ultrasonic cleaning is performed for 8-12 minutes. Isopropyl alcohol can effectively dissolve grease and other organic matter, accelerating the cleaning process. Ethanol can dissolve isopropyl alcohol and remove residual isopropyl alcohol from the substrate. Ultrapure water can wash away the ethanol. Ultrasonic cleaning makes the cleaning more thorough, ensuring a clean environment for the growth of the hafnium dioxide film on the substrate.

[0017] According to the above scheme, in step 2), the carrier gas is Ar and the reaction gas is O2.

[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] Provided is a silicon-doped hafnium dioxide film prepared by the above preparation method.

[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 in a pure tetragonal phase.

[0024] The present invention provides a method for preparing a silicon-doped hafnium dioxide thin 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 up 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 evenly mixed on the surface of the silicon substrate, thereby achieving the purpose of uniform doping, avoiding 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 thin 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 the deposition apparatus. An atmosphere with high carrier gas and low reaction gas is adopted, and the volatilization rate and concentration of the precursor atmosphere are strictly controlled to uniformly mix the precursor 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 thin film. The method is simple to operate, has a controllable deposition rate, is low in cost, has good reproducibility, and the resulting film has uniform thickness and uniform composition, and has important application prospects.

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

[0028] 3. Furthermore, by taking advantage of the fact that the diffusion rate of silicon in the substrate increases with increasing temperature, by varying the deposition temperature, 0-50% silicon-doped hafnium dioxide films can be precisely prepared to regulate the content of tetragonal hafnium dioxide in the film. At the same time, by adjusting the precursor volatilization temperature and the dilution gas flow rate, the film thickness can be controlled, achieving controllable growth of the hafnium dioxide film. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 2 Surface and cross-sectional SEM images of the hafnium dioxide 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 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 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 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 film obtained in Comparative Example 1, respectively; (a2) and (d2) are surface and cross-sectional SEM images of the 130 nm hafnium dioxide film obtained in Example 4 with a silicon doping amount of 50%, respectively.

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

[0032] Figure 4 Schematic diagram of the reaction device according to an 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 the 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 was ultrasonically cleaned for 10 min using isopropyl alcohol (purity of 99.5 wt%), ethanol (concentration of 99.5 wt%) and ultrapure water in sequence;

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

[0039] 3) Set the heating programs for 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. 60 seconds 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 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 with a flow rate of 50sccm, the reaction gas is O2 with a flow rate of 20sccm, and the dilution gas is Ar with a flow rate of 500sccm. After the two temperature zones reach the target temperature, the program automatically starts timing, and heating is stopped after maintaining the target temperature for 7 minutes.

[0040] 4) Stop ventilation, adjust the flapper valve to pump the chamber pressure back to 7 Pa, and allow the deposition apparatus to cool 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 was ultrasonically cleaned for 10 min using isopropyl alcohol (purity of 99.5 wt%), ethanol (concentration of 99.5 wt%) and ultrapure water in sequence;

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

[0045] 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 220℃ at the rate of 4.4℃ / min, the deposition temperature zone is heated to the target temperature 1000℃ at the rate of 20℃ / min, and the two temperature zones are controlled 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, transport the precursor vapor in the precursor tank to the surface of the single crystal silicon substrate in the deposition device by the carrier gas, and introduce the reaction gas and the dilution gas into the deposition device, adjust the baffle valve to make the cavity pressure to 200Pa, wherein the carrier gas is Ar, the flow rate is 50sccm, the reaction gas is O2, the flow rate is 10sccm, and the dilution gas is Ar, the flow rate is 400sccm; after the two temperature zones reach the target temperature, the program automatically starts timing, and stops heating after maintaining the target temperature for 5min;

[0046] 4) Stop the gas, adjust the baffle valve to make the cavity pressure to 7Pa again, and the deposition device is naturally cooled in the room temperature environment, and the 40nm hafnium dioxide film with the silicon doping amount of 29% is obtained.

[0047] Example 3

[0048] The application provides a preparation method of a silicon-doped hafnium dioxide film, which comprises the following steps:

[0049] 1) Cut a (100) single crystal silicon wafer with the area of 1*1cm 2 , and clean the single crystal silicon wafer by ultrasonic wave with isopropyl alcohol (the purity is 99.5wt%), ethanol (the concentration is 99.5wt%) and ultrapure water in sequence for 10min;

[0050] 2) Weigh 0.2g of hafnium acetylacetonate powder by a balance and put 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 put the porcelain boat into a quartz tube in the deposition device, and the precursor tank gas nozzle is 6cm away from the single crystal silicon substrate. Close the flange at the outlet of the cavity, and open the vacuum pump to vacuumize to 7Pa;

[0051] 3) Set the heating programs for 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. 58 seconds 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 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 with a flow rate of 50sccm, the reaction gas is O2 with a flow rate of 10sccm, and the dilution gas is Ar with a flow rate of 300sccm. 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 5 minutes.

[0052] 4) The ventilation was stopped, and the baffle valve was adjusted to pump the chamber pressure down to 7 Pa again. The deposition apparatus was cooled naturally at room temperature to obtain a 40 nm hafnium dioxide film with a silicon doping content 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 was ultrasonically cleaned for 10 min using isopropyl alcohol (purity of 99.5 wt%), ethanol (concentration of 99.5 wt%) and ultrapure water in sequence;

[0056] 2) Weigh 0.2g of hafnium acetylacetonate powder using a balance and place it into a precursor tank. Using a hot-wall horizontal chemical vapor deposition apparatus, place the cleaned single-crystalline silicon substrate on an alumina boat, which is then placed in a quartz tube within the deposition apparatus. Keep the nozzle of the precursor tank 8cm away from the single-crystalline silicon substrate. Close the flange at the chamber outlet and pump the vacuum to 7Pa.

[0057] 3) Set the heating programs for 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. 55 seconds 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 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 with an inlet flow rate of 50sccm, the reaction gas is O2 with an inlet flow rate of 20sccm, and the dilution gas is Ar with an inlet flow rate of 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 down to 7 Pa again. The deposition apparatus was cooled naturally at room temperature to obtain the 40 nm undoped hafnium dioxide thin 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 was ultrasonically cleaned for 10 min using isopropyl alcohol (purity of 99.5 wt%), ethanol (concentration of 99.5 wt%) and ultrapure water in sequence;

[0062] 2) Weigh 0.2g of hafnium acetylacetonate powder using a balance and place it into a precursor tank. Using a hot-wall horizontal chemical vapor deposition apparatus, place the cleaned single-crystal silicon substrate on an alumina boat. The boat is then placed into a quartz tube in the deposition temperature zone of the deposition apparatus. Keep the nozzle of the precursor tank 5cm away from the single-crystal silicon substrate. Close the flange at the chamber outlet and pump the vacuum to 7Pa.

[0063] 3) Set the heating programs for 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. 60 seconds 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 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 with an inlet flow rate of 100sccm, the reaction gas is O2 with an inlet flow rate of 10sccm, and the dilution gas is Ar with an inlet flow rate of 50sccm. After the two temperature zones reach the target temperature, the program automatically starts timing, and stops heating after maintaining the target temperature for 9 minutes.

[0064] 4) Stop ventilation, adjust the baffle valve to pump the chamber pressure back to 7 Pa, and allow the deposition apparatus to cool 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 below. Figure 1 (a) shows that when the silicon doping amount in Example 1 is 50%, the tetragonal hafnium dioxide content is 100%; Figure 1 (b) shows that when the silicon doping amount is 29% in Example 2, the content of tetragonal hafnium dioxide is 82%; Figure 1 (c) shows that when the silicon doping amount is 17% in Example 2, 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, wherein: Figure 2 (a) shows that 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 cross section of the film 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 the thickness is 130nm.

[0067] Figure 3 The XPS spectra of the hafnium dioxide films obtained in Examples 1-4 of the present invention and Comparative Example 1 are shown. Figure 3 (a) is the 4f orbital of 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 calculated to be 50% 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 calculated to be 20% based on the area ratio of the two peaks. Figure 3 (a1) is the 4f orbital of Hf element. The 4f7 / 2 and 4f5 / 2 split peaks appear in the figure. 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 16-18eV, 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 such 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) Place a weighed powder precursor in a precursor tank; place a single crystal silicon substrate in a chemical vapor deposition apparatus, evacuate to below 10 Pa, and simultaneously heat the precursor tank and the single crystal silicon substrate; the precursor is hafnium acetylacetonate powder; the target temperature for heating the precursor tank is 200-250°C, and the target temperature for heating the substrate is 810-1100°C, with the precursor tank and the single crystal silicon substrate reaching the target temperatures 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 apparatus using a carrier gas, and the reaction gas and dilution gas are introduced. The deposition pressure is adjusted to a certain level, and the deposition time is set to start the reaction. The carrier gas flow rate is 25-200 sccm, and the reaction gas flow rate is 10-20 sccm. Upon completion of the reaction, a silicon-doped hafnium dioxide film containing tetragonal hafnium dioxide is obtained.

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 single crystal silicon substrate is a (100) oriented silicon single crystal substrate, which is single-sided polished.

5. The preparation method according to claim 1, characterized in that In the step 2), the carrier gas is Ar; the reaction gas is O2; and the dilution gas is Ar, with an inflow flow rate of 50 to 500 sccm.

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

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

8. A silicon-doped hafnium dioxide thin film prepared by the preparation method according to any one of claims 1 to 7.

9. The hafnium dioxide thin film according to claim 8, wherein Silicon doping amount ≤50%.

Images