Method for preparing RE-Si-O porous film by laser-assisted CVD

Abstract

The present application relates to the technical field of ceramic material preparation, in particular to a method for preparing RE-Si-O porous film by laser-assisted CVD. The method uses laser-enhanced chemical vapor deposition to prepare porous RE-Si-O film, uses the introduction of RE elements with ferromagnetic properties, and the movement and collision of gas molecules in the CVD reaction chamber to form loose RE-Si-O eutectic structure porous film. Compared with the traditional method for preparing porous ceramics, the method can not only reduce the deposition temperature, improve the deposition rate, improve the impurity phase and defects, obtain high uniformity of the film, but also can change the porosity of the RE-Si-O porous film by adjusting the pressure and other parameters, effectively improve the permeability, heat resistance and corrosion resistance of different grades of RE-Si-O porous film.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of ceramic material preparation, in particular to a method for preparing a RE-Si-O porous film through laser-assisted CVD. BACKGROUND

[0002] The SiO2 porous film has good chemical stability and thermal stability and is widely applied to separation membranes and catalyst carriers, etc., but the strength of the pure SiO2 porous material is low, and the working temperature is not higher than 1473K; the RE-Si-O film doped with rare earth elements RE has a high melting point, a low vapor pressure and superior oxygen diffusion barrier and plasma resistance, and is suitable for applications such as oxidation-resistant coatings, thermal barrier coatings and environmental barrier coatings.

[0003] At present, the prepared methods of the RE-Si-O porous film mainly include phase separation technology and sol-gel method.

[0004] A team of Zhang Buxing of South China Institute of Technology adopts the nano ceramic particle and polymer phase separation technology to prepare a low-density, high-porosity porous Al2O3-SiO2 through sintering at 1673K for 2h. However, the phase separation method has the problems of high sintering temperature, long preparation period, easy introduction of impurities, low purity of the coating, insufficient overall uniformity and limited use performance, and in addition, the preparation period of the phase separation method is long.

[0005] The sol-gel method is a more common and effective means for preparing the porous ceramic. A team of Ye Feng of Harbin Institute of Technology successfully prepares a SiO2 aerogel / porous Si3N4 composite material with high specific surface area and low thermal conductivity through the sol-gel method. The SiO2 sol only needs to be kept at 1073K for 2h to obtain the aerogel, but the period of the previous solution treatment is as long as 96h, and in this process, the film is prone to cracks, affecting the use performance. On the other hand, the film is not convenient to coat for the workpieces with complex shapes, and it is difficult to realize large-scale production.

[0006] Patent document CN110534348A discloses an electrode material based on 3C-SiC thin film and a preparation method thereof, and the preparation method comprises the following steps: 1) placing a single crystal Si substrate into a deposition chamber, vacuumizing the deposition chamber, and reducing the pressure in the deposition chamber to below 10 Pa; 2) introducing H2 into the deposition chamber from the side of the deposition chamber, opening the laser to irradiate the surface of the single crystal Si substrate, etching the single crystal Si substrate under high temperature conditions by using H2, forming a concave-convex structure on the surface of the substrate, and after etching, introducing a carrier gas containing HMDS into the deposition chamber from the side of the deposition chamber, adjusting the deposition pressure in the deposition chamber, and depositing and growing a 3C-SiC porous thin film. Although the method can prepare a silicon carbide porous thin film, since the porous structure is mainly based on the concave-convex structure formed by hydrogen etching, only a porous thin film can be prepared at the initial stage of the reaction, and the subsequent thin film is still a dense thin film.

[0007] Therefore, it is imperative to provide a preparation method of a silicon dioxide porous thin film which has uniform pores, adjustable pores to meet different application requirements, fast deposition speed and simple preparation process. SUMMARY

[0008] In view of the defects of the prior art, the purpose of the present application is to provide a method for preparing a RE-Si-O porous thin film by laser-assisted chemical vapor deposition, so as to prepare a porous RE-Si-O thin film with adjustable and uniform pores, and to solve the technical problems of poor pore uniformity, complex preparation process and non-adjustable pores of the prior art for preparing a silicon dioxide porous thin film.

[0009] To achieve the above-mentioned purpose, the present application provides a method for preparing a RE-Si-O porous thin film by laser-assisted chemical vapor deposition, comprising the following steps:

[0010] Step S100: introducing RE reaction precursor vapor, Si reaction precursor vapor and reaction gas into the reaction cavity by using a carrier gas;

[0011] Step S200: under the action of heating, the precursor vapor molecules of RE and Si in the reaction precursor vapor are dissociated into RE and Si active ions or ion groups, which reach the substrate surface by diffusion; the substrate has a matching lattice orientation and thermal expansion coefficient with the RE-Si-O porous thin film material;

[0012] Step S300: the RE and Si active ions or ion groups obtain energy under laser irradiation to improve the reaction activity, react with the reaction gas to form a RE-Si-O eutectic structure, and the generated RE-Si-O solid product is deposited on the surface of the substrate, and the crystal nucleus continuously grows and aggregates to form a RE-Si-O porous thin film.

[0013] Preferably, the step S100 dissolves the solid-state precursor powder of RE in an organic solvent to obtain a mixed solution of RE precursor; and the mixed solution of RE precursor and the organic silicon raw material are heated respectively to obtain RE reaction precursor vapor and Si reaction precursor vapor.

[0014] Further preferably, the solid-state precursor powder of RE is a chelate of RE and a β-diketone group, the β-diketone group is one or more of dpm, acac and tetraglyme; the organic solvent is one or more of THF, ethanol and toluene; and the organic silicon raw material is TEOS and / or MM.

[0015] Preferably, the carrier gas is Ar gas, and the reaction gas is O2; the flow rate of the carrier gas is 1000-2000sccm, and the flow rate of the reaction gas is 200-800sccm.

[0016] Preferably, the pressure of the reaction cavity in the step S100 is 0.5-90kPa, further preferably 20-90kPa, and more preferably 20-50kPa.

[0017] Preferably, the substrate in the step S200 is quartz or alumina.

[0018] Preferably, the heating temperature in the step S200 is 523-1473K.

[0019] Preferably, the power of the laser in the step S300 is 50-300W.

[0020] Preferably, the deposition time in the step S300 is 30-3600s.

[0021] Preferably, the molar ratio of RE to Si in the reaction precursor vapor is (0.02-5):1.

[0022] Overall, compared with the prior art, the above technical solutions conceived by the present application have the following advantages

[0023] Beneficial effects:

[0024] (1) The method for preparing RE-Si-O porous thin film by laser-assisted chemical vapor deposition provided by the present application, under the action of heating and laser irradiation, the RE and Si reaction precursor vapor decomposes and reacts with the reaction gas, under the action of the alternating magnetic field provided by the CVD reaction cavity, the magnetic element atoms also change alternately, the rare earth element is doped into the crystal lattice of silicon oxide to form holes, dislocations, micropores and other defects, and at the same time, by controlling the cavity pressure, the average free path and collision probability of the raw material molecules during film formation are controlled, the diffusion activation energy of silicon oxide is affected, and a porous structure thin film is formed.

[0025] (2) The application provides a method for preparing RE-Si-O porous film by laser-assisted chemical vapor deposition, which can obtain loose porous structure film by introducing RE, adjusting reaction pressure, and obtaining uniform temperature field and energy field by laser assistance, compared with traditional LCVD, and can adjust film porosity by adjusting pressure, improve RE-Si-O porous film oxidation resistance and plasma erosion resistance, and has huge application prospect in large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A flow chart of the method for preparing RE-Si-O porous film according to the application;

[0027] Figure 2 Content (a) is the cross-sectional morphology of the porous film prepared according to Example 1 of the application; and content (b) is the cross-sectional morphology of the dense film prepared according to Comparative Example 2.

[0028] Figure 3 Content (a) is the surface morphology of the porous film prepared according to Example 1 of the application; and content (b) is the surface morphology of the dense film prepared according to Comparative Example 2.

[0029] Figure 4 Content (a) is the cross-sectional morphology of the dense Si-O film prepared according to Comparative Example 3 without doping rare earth elements. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the application clearer, the application is further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application, and are not used to limit the application.

[0031] The application uses a laser-assisted chemical vapor deposition method to rapidly prepare RE-Si-O porous films on a substrate, and the films have high oxidation resistance, good thermal stability and strong corrosion resistance. First, RE reaction precursor vapor, Si reaction precursor vapor and reaction gas are mixed and fed into a reaction cavity; a substrate with a lattice orientation and a thermal expansion coefficient matching the RE-Si-O porous film material and good chemical stability and mechanical properties is selected; under the action of heating, the RE and Si precursor vapor molecules in the reaction precursor vapor are dissociated into RE and Si active ions or ion groups, which reach the substrate surface through diffusion; the RE and Si active ions or ion groups obtain more energy under laser irradiation to improve the reaction activity and reduce the deposition temperature, so that a RE-Si-O interpenetrating eutectic structure is obtained, and a RE-Si-O solid product is deposited on the substrate surface, and the crystal nucleus continuously grows and aggregates into a RE-Si-O film. During the experiment, the porosity of the film can be controlled by setting different pressures. Under a higher pressure condition, the molecular motion rate increases and the collision frequency is frequent, a more loose lattice structure is generated, the film grain spacing is increased, and the film presents a uniform porous structure.

[0032] Specifically, in some embodiments of the application, a method for preparing a RE-Si-O porous film by a laser-assisted chemical vapor deposition method is provided, as shown in the following formula (I): Figure 1 The method comprises the following steps:

[0033] Step S100: Dissolving a solid-state precursor powder of RE (Rare Earth) in an organic solvent to obtain a mixed solution of the RE precursor, heating the mixed solution of the RE precursor and a raw material of organosilicon respectively to obtain RE reaction precursor vapor and Si reaction precursor vapor, mixing the RE reaction precursor vapor and the Si reaction precursor vapor with carrier gas and feeding them into a reaction cavity, and feeding reaction gas into the reaction cavity through a nozzle;

[0034] Step S200: Selecting a substrate with a lattice orientation and a thermal expansion coefficient matching the RE-Si-O porous film material and good chemical stability and mechanical properties; under the action of heating, the RE and Si precursor vapor molecules in the reaction precursor vapor are dissociated into RE and Si active ions or ion groups, which reach the substrate surface through diffusion;

[0035] Step S300: The RE and Si active ions or ion groups obtain more energy under laser irradiation to improve the reaction activity and reduce the deposition temperature, so that a RE-Si-O interpenetrating eutectic structure is obtained, and a RE-Si-O solid product is deposited on the substrate surface, and the crystal nucleus continuously grows and aggregates into a RE-Si-O film.

[0036] In some embodiments, the solid-state precursor powder of RE in step S100 is a chelate of RE and a β-diketone group, which includes dpm (2,2,6,6-tetramethyl-3,5-heptanedione), acac (acetylacetone), tetraglyme (tetraethylene glycol dimethyl ether), etc. The rare earth element RE is one of the seventeen metal elements in the lanthanide series and scandium and yttrium in the periodic table. The porous thin film substrate material of the present application is SiO2, and the doping element is the rare earth element RE. It is required that the doping atom RE is a metal element with a large difference in radius from the parent phase atom Si and with matching parameters such as lattice constant and thermal expansion coefficient. The RE-Si-O porous thin film prepared by the present application preferably selects Y, La and Ce.

[0037] In some embodiments, the organic solvent is THF, ethanol, toluene, etc., and the organic silicon raw material is TEOS (tetraethoxysilane, also known as tetraethyl silicate), MM (hexamethyldisiloxane), etc.

[0038] In some embodiments, the carrier gas is Ar carrier gas, and the reaction gas is O2. The flow rate of the carrier gas is 1000-2000 sccm, and the flow rate of the reaction gas is 200-800 sccm.

[0039] In some embodiments, the pressure of the reaction cavity in step S100 is 0.5-90 kPa, preferably 20-90 kPa, and more preferably 20-50 kPa.

[0040] The substrate selected in the present application has a matching lattice orientation and thermal expansion coefficient with the RE-Si-O porous thin film material and has good chemical stability and mechanical properties itself, including but not limited to quartz, alumina, etc.

[0041] In some embodiments, the heating temperature in step S200 is 523-1473 K, and more preferably 1073 K-1273 K. The power of the laser in step S300 is 50-300 W, and more preferably 150-250 W. The deposition time in step S300 is 30-3600 s, and the thickness of the RE-Si-O thin film prepared is 0.2-500 μm.

[0042] The molar ratio of RE to Si in the precursor vapor during the preparation of the RE-Si-O thin film can be (0.02-5):1, and more preferably (0.4-3):1; RE and Si, O atoms form a RE-Si-O interpenetrating eutectic structure. By adjusting the process parameters such as pressure, the porosity of the RE-Si-O porous thin film can be controlled. The theoretical porosity of the RE-Si-O porous thin film is 0-90%. It is speculated that the reason why a porous film can be formed is that most of the RE is magnetic, and a certain amount of rare earth elements is doped into the film during the film growth process. These magnetic elements are distributed in the silicon oxide lattice, and under the alternating magnetic field of the CVD, the magnetic element atoms also change alternately, forming vacancies, dislocations, micropores and other defects in the silicon oxide lattice. By adjusting the pressure in the cavity, the average free path and collision probability of the raw material molecules during film formation can be controlled, thereby affecting the diffusion activation energy of silicon oxide at high temperature, so as to obtain a porous film. It is found in experiments that if RE is not doped, the silicon dioxide film prepared by the same laser-assisted CVD process is a dense film and cannot obtain a porous film.

[0043] The following is an example:

[0044] Example 1

[0045] In this embodiment, a Ce-doped SiO2 porous thin film is prepared by medium-pressure laser chemical vapor deposition, which is denoted as a Ce-Si-O porous thin film, and the steps are as follows:

[0046] Step S100: 1g of solid precursor powder of Ce(tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) cerium(IV), i.e., Ce(dpm)4, is dissolved in 100ml of THF organic solvent at a ratio of 1g / 100ml to obtain a precursor solution, which is delivered to a volatilization tank and heated to 573K to obtain precursor vapor; liquid organosilicon raw material TEOS is preheated to 323K to obtain silicon vapor, which is mixed with the Ce:Si molar ratio of 3:7 and delivered to the CVD reaction chamber by Ar carrier gas with a flow rate of 1500sccm, and the pressure in the reaction chamber is maintained at 25kPa, while O2 is sent into the reaction chamber through the nozzle at a flow rate of 500sccm;

[0047] Step S200: an alumina substrate (12mm×12mm×2.5mm) with a lattice orientation and a thermal expansion coefficient matching SiO2 and good chemical stability and mechanical properties is selected, the surface is cleaned with anhydrous ethanol and blown dry, and placed on a heating table and heated to 1173K by a built-in metal wire heating device in the reaction chamber;

[0048] Step S300: irradiate the substrate surface through the reaction chamber glass window using a 210W Nd:YAG laser to make the light spot completely cover the substrate, and the vapor molecules containing Ce and Si are dissociated into active ions or ion groups under the action of light and heat, reach the substrate surface by diffusion, generate Ce-Si-O solid-state products deposited on the substrate surface, and the crystal nucleus grows and aggregates, the deposition time lasts for 300s, and the porous Ce-Si-O film with a thickness of about 23μm shown in content (a) is obtained, and the deposition rate is 276μm h Figure 2 The thickness of the porous Ce-Si-O film shown in content (a) is about 23μm, and the deposition rate is 276μm h -1 The main phase of the film is Ce2SiO5, Figure 3 Content (a) is the surface morphology of the Ce-Si-O porous film, and the apparent porosity of the sample is greater than 35%.

[0049] Step S400: carry out the anti-plasma corrosion experiment of the sample in CF4 and O2 atmosphere, and set the plasma power to 700W, and the duration is 3h, and the sample surface micro-morphology has no obvious corrosion. The film has excellent oxidation resistance and plasma corrosion resistance.

[0050] Comparative Example 1

[0051] Comparative Example 1 uses medium pressure chemical vapor deposition to prepare Ce-doped SiO2 porous film, which is recorded as Ce-Si-O porous film, and the steps are as follows:

[0052] Step S100: dissolve 1g of Ce solid precursor powder, cerium(IV) tetra(2,2,6,6-tetramethyl-3,5-heptanedionate), i.e. Ce(dpm)4, in 100ml THF organic solvent at a ratio of 1g / 100ml to obtain a precursor solution, deliver it into a volatilization tank and heat it to 573K to obtain a precursor vapor; preheat the liquid organosilicon raw material TEOS to 323K to obtain a silicon vapor, mix them in a Ce:Si molar ratio of 3:7, and deliver them into the CVD reaction chamber by an Ar carrier gas with a flow rate of 1500sccm, and at the same time, send O2 into the reaction chamber body through a nozzle at a flow rate of 500sccm;

[0053] Step S200: select an alumina substrate (12mm×12mm×2.5mm) with a lattice orientation and a thermal expansion coefficient matching SiO2 and good chemical stability and mechanical properties itself, clean the surface with anhydrous ethanol and blow dry, place it on a heating table, and heat it to 1173K by a built-in metal wire heating device in the reaction chamber;

[0054] Step S300: The vapor molecules containing Ce and Si are dissociated into active ions or ion groups under the action of heat, reach the substrate surface by diffusion, generate Ce-Si-O solid-state products, and deposit on the substrate surface. The crystal nucleus grows and aggregates. The deposition time lasts for 300 s. The Ce-Si-O thin film with a thickness of about 480 nm is obtained, and the deposition rate is 5.8 μm h -1 .

[0055] The comparative example is the same as the other conditions of Example 1, except that the laser is not introduced in step S300. By comparing with the example, it is found that the thin film deposition rate is very low without laser assistance, which shows that the introduction of laser can significantly improve the deposition rate of Ce-Si-O porous thin film.

[0056] Example 2

[0057] In this example, a Ce-doped SiO2 porous thin film is prepared by medium pressure chemical vapor deposition, which is recorded as a Ce-Si-O porous thin film. The steps are as follows:

[0058] Step S100: 1 g of solid precursor powder of Ce(tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) cerium(IV), i.e., Ce(dpm)4, is dissolved in 100 ml of THF organic solvent to obtain a precursor solution at a ratio of 1 g / 100 ml. The precursor solution is delivered to a volatilization tank and heated to 573 K to obtain a precursor vapor. The liquid organosilicon raw material TEOS is preheated to 323 K to obtain a silicon vapor. The Ce:Si molar ratio is 7:3, and the mixture is delivered to the CVD reaction chamber by an Ar carrier gas with a flow rate of 1500 sccm. The pressure in the reaction chamber is maintained at 25 kPa. At the same time, 500 sccm of O2 is sent into the reaction chamber through a nozzle;

[0059] Step S200: An alumina substrate (12 mm x 12 mm x 2.5 mm) with a lattice orientation and a thermal expansion coefficient matching SiO2 and good chemical stability and mechanical properties itself is selected. The surface is cleaned with anhydrous ethanol and blown dry. It is placed on a heating table and heated to 1173 K by a built-in metal wire heating device in the reaction chamber.

[0060] Step S300: A 210 W Nd:YAG laser is used to irradiate the substrate surface through the reaction chamber glass window, so that the light spot completely covers the substrate. The vapor molecules containing Ce and Si are dissociated into active ions or ion groups under the action of heat, reach the substrate surface by diffusion, generate Ce-Si-O solid-state products, and deposit on the substrate surface. The crystal nucleus grows and aggregates. The deposition time lasts for 300 s. The main phase of the thin film is Ce2Si2O7.

[0061] The other conditions in this embodiment are the same as in embodiment 1, except that in step S100 the Ce:Si molar ratio is adjusted from 3:7 to 7:3. Experiments show that the phase composition of Ce-Si-O porous thin films can be adjusted by adjusting the raw material ratio.

[0062] Comparative Example 2

[0063] In this embodiment, Ce-doped SiO2 dense thin film, denoted as Ce-Si-O dense thin film, is prepared by laser chemical vapor deposition. The steps are as follows:

[0064] Step S100: 1g of Ce solid precursor powder tetra(2,2,6,6-tetramethyl-3,5-heptadecanoic acid)cerium(IV), i.e. Ce(dpm)4, is dissolved in 100ml of THF organic solvent at a ratio of 1g / 100ml to obtain a precursor solution. This solution is then transferred to a volatilization tank and heated to 573K to obtain precursor vapor. Liquid organosilicon raw material TEOS is preheated to 323K to obtain silicon vapor. The silicon vapor is mixed with Ce:Si molar ratio of 3:7 and transported to the CVD reaction chamber by Ar carrier gas at a flow rate of 1500sccm. The pressure inside the reaction chamber is maintained at 750Pa. At the same time, O2 is introduced into the reaction chamber through a nozzle at a flow rate of 500sccm.

[0065] Step S200: Select an alumina substrate (12mm×12mm×2.5mm) that has a matching lattice orientation and thermal expansion coefficient with SiO2 and has good chemical stability and mechanical properties. Clean the surface with anhydrous ethanol and blow it dry. Place it on the heating stage and heat it to 1173K through the built-in metal wire heating device in the reaction chamber.

[0066] Step S300: A 210W Nd:YAG laser is used to irradiate the substrate surface through the glass window of the reaction chamber, completely covering the substrate with a light spot. Ce and Si vapor molecules dissociate under the influence of light and heat, becoming active ions or ion clusters. These ions diffuse to the substrate surface, generating Ce-Si-O solid products that deposit on the substrate surface. Crystal nuclei grow and aggregate. The deposition time lasts 300 seconds, resulting in the desired product. Figure 2 Content (b) shows the cross-sectional morphology of a Ce-Si-O film with a thickness of approximately 26 μm and a deposition rate of 312 μm / h. -1 .

[0067] Comparative Example 2 is identical to Example 1 in all other conditions except that the pressure in the reaction chamber in step S100 is adjusted from 25 kPa to 750 Pa. Figure 3 Content (b) shows the surface morphology of the film obtained in this comparative example, with an apparent porosity of less than 0.05%. The experiment shows that the porosity of Ce-Si-O film can be adjusted by adjusting the deposition pressure to obtain films with different densities.

[0068] Comparative Example 3

[0069] The comparative example used a middle-pressure laser chemical vapor deposition to prepare a SiO2 film, and the steps were as follows:

[0070] Step S100: The liquid organosilicon raw material TEOS was preheated to 323 K to obtain silicon vapor, and was transported to the CVD reaction cavity by Ar carrier gas at a flow rate of 1500 seem, the pressure in the reaction cavity was maintained at 25 kPa, and O2 was sent into the reaction cavity through a nozzle at a flow rate of 500 seem;

[0071] Step S200: An alumina substrate (12 mm x 12 mm x 2.5 mm) with a lattice orientation and a thermal expansion coefficient matched with SiO2 and good chemical stability and mechanical properties was selected, the surface was cleaned with anhydrous ethanol and blown dry, and was placed on a heating table and heated to 1173 K by a built-in metal wire heating device in the reaction cavity;

[0072] Step S300: A 210 W Nd:YAG laser was used to irradiate the substrate surface through the reaction cavity glass window, so that the light spot completely covered the substrate, the Si-containing vapor molecules were dissociated into active ions or ion groups under the action of light and heat, diffused to the substrate surface, and deposited as Si-O solid products on the substrate surface, the crystal nucleus grew and gathered, the deposition time lasted for 300 s, and a Si-O film as shown in FIG. 2 was obtained, the cross-sectional morphology was dense, and no porous structure was shown. Figure 4

[0073] The other conditions of the comparative example were the same as those of Example 1, except that no rare earth element precursor vapor was introduced into the reaction cavity, and the prepared film was not doped with RE elements. It can be seen that when no RE is doped, a porous Si-O film cannot be prepared. It is also shown that when a porous film is prepared by the preparation method of the application, in addition to the need to control the appropriate pressure in the reaction cavity, the introduction of a rare earth element is one of the key factors for preparing a porous RE-Si-O film. It is speculated that the possible reason for forming a porous film is that the rare earth element with ferromagnetism is doped in the silicon oxide lattice, and under the alternating magnetic field of the CVD, the magnetic element atoms also change alternately, forming vacancies, dislocations, micropores and other defects on the silicon oxide lattice. By controlling the cavity pressure, the average free path and collision probability of the raw material molecules during film formation are controlled, the diffusion activation energy of silicon oxide is affected, and a porous structure film is formed.

[0074] Those skilled in the art will readily understand that the above description is only preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A method for preparing RE-Si-O porous thin films by laser-assisted chemical vapor deposition, characterized in that, Includes the following steps: Step S100: The RE reaction precursor vapor, Si reaction precursor vapor, and reaction gas are introduced into the reaction chamber using a carrier gas; specifically: the solid precursor powder of RE is dissolved in an organic solvent to obtain a mixed solution of RE precursor; the mixed solution of RE precursor and the organosilicon raw material are heated respectively to obtain RE reaction precursor vapor and Si reaction precursor vapor; the solid precursor powder of RE is a chelate of RE and β-diketone groups, wherein the β-diketone groups are dpm and / or acac; the pressure of the reaction chamber is 20-90 kPa; Step S200: Under heating, the RE and Si precursor vapor molecules in the reaction precursor vapor dissociate into RE and Si active ions or ion clusters, which diffuse to the substrate surface; the substrate and the RE-Si-O porous thin film material have matching lattice orientation and thermal expansion coefficient. Step S300: RE and Si active ions or ion clusters gain energy under laser irradiation to improve their reactivity and react with the reaction gas to form a RE-Si-O eutectic structure. The generated RE-Si-O solid product is deposited on the substrate surface, and the crystal nuclei continue to grow and aggregate to form a RE-Si-O porous film.

2. The method as described in claim 1, characterized in that, The organic solvent mentioned in step S100 is one or more of THF, ethanol, and toluene; The organosilicon raw material is TEOS and / or MM.

3. The method as described in claim 1, characterized in that, The carrier gas is Ar gas, and the reactant gas is O2; the flow rate of the carrier gas is 1000-2000 sccm, and the flow rate of the reactant gas is 200-800 sccm.

4. The method as described in claim 1, characterized in that, The substrate in step S200 is quartz or alumina.

5. The method as described in claim 1, characterized in that, The heating temperature described in step S200 is 523-1473K.

6. The method as described in claim 1, characterized in that, The power of the laser in step S300 is 50-300W.

7. The method as described in claim 1, characterized in that, The deposition in step S300 takes 30-3600 s.

8. The method as described in claim 1, characterized in that, The molar ratio of RE to Si in the precursor vapor is (0.02-5):1.

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