Method and device for preparing thin film through infrared laser heating

Abstract

The invention relates to the technical field of preparation of films through physical vapor deposition, in particular to a method and device for preparing a film through infrared laser heating evaporation vapor deposition. The method comprises the following steps: heating a source material through an external first infrared laser in a vacuum film growth cavity, and evaporating and depositing the source material on a substrate to obtain the film. According to the thin film preparation method, the source material and the substrate can be conveniently replaced through the rapid sample injection cavity under the condition that the vacuum environment required by growth is not damaged, the source material can be degassed and heated within a short time, and the growth efficiency is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of preparing thin films by physical vapor deposition, and in particular to a method and a device for preparing thin films by infrared laser heating. Background Art

[0002] Thin film materials have wide application demands in many fields such as microelectronics, optoelectronics, optics, solid-state batteries, surface catalysis, etc. There are two commonly used methods for preparing high-quality thin films in ultra-vacuum, Molecular Beam Epitaxy (MBE) and Pulsed Laser Deposition (PLD). Both growth methods have their own obvious advantages and disadvantages.

[0003] Molecular beam epitaxy (MBE): The source material in the crucible is heated by a resistance wire or an electron beam to produce vapor that is deposited on a substrate at an appropriate temperature to obtain the desired thin film. This method has significant advantages for materials with high melting points. This method can produce higher quality films and can control the layer-by-layer growth of the film, but the deposition rate is low. The film growth size is limited by the size of the focused molecular beam. It is generally used in laboratories of scientific research institutions. In actual operation, the size of the MBE evaporation source crucible is small, and the vacuum must be broken when the source material is replaced. Therefore, it takes several days to restore the ultra-high vacuum when replacing the source and adding the source material. In addition, in order to ensure the cleanliness of the evaporated molecular beam, degassing must be performed before evaporation to remove the gas and impurities in the resistance wire, source material, crucible, and evaporation source itself. This process also takes several days, which leads to lengthy preliminary preparations for MBE film preparation.

[0004] Pulsed laser deposition (PLD): A thin film is obtained by burning the surface of the target material with a high-energy pulsed laser (wavelength of 200-400nm, 248nm excimer laser is commonly used) to sputter plasma and deposit it on the surface of the substrate. This method has high growth efficiency and fast growth rate. The required vacuum environment for growth can be obtained within a few hours, but it has very high requirements on the quality of the target material. Otherwise, the sputtered plasma is often mixed with clusters, target material impurities, etc., resulting in poor quality of the film and many defects, and it is difficult to control the layer-by-layer growth of the film. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method and device for preparing thin films by infrared laser heating, which uses an infrared laser to directly radiate and heat the source material, evaporate atoms or molecular beams and deposit them on a substrate, thereby achieving rapid and controllable growth of high-quality thin films, thereby solving the problems in the prior art.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for preparing a thin film by infrared laser heating, the method comprising heating a source material in a vacuum thin film growth chamber by an external first infrared laser to evaporate and deposit the source material onto a substrate to obtain a thin film.

[0007] In a specific embodiment, the preparation method comprises the following steps:

[0008] 1) Place the source material in a crucible on the source material evaporation table and compact it, and place the substrate on the substrate sample holder;

[0009] 2) placing a source material evaporation table containing source materials and a substrate sample holder containing substrates into a vacuum thin film growth chamber;

[0010] 3) adjusting the first infrared laser or the second infrared laser to focus on the back of the substrate sample holder, turning on the first infrared laser or the second infrared laser to heat and degas the substrate and the sample holder, the degassing temperature is determined by the annealing temperature required by the substrate, and turning off the laser after the degassing is completed;

[0011] 4) adjusting the first infrared laser to focus on the back of the source material evaporation table and the source material respectively, turning on the first infrared laser to heat the back of the source material evaporation table and the source material respectively, and performing a rapid degassing process. The degassing temperature is determined by the required evaporation temperature of the source material. After the degassing is completed, the laser is turned off;

[0012] 5) Place the source material evaporation table in the center of the growth chamber, with the substrate sample holder facing the substrate sample holder, and keep a distance of 2-10 cm between the source material and the substrate;

[0013] 6) adjusting the first infrared laser to focus on the source material in the source material evaporation table, turning on the first infrared laser to heat the source material to the evaporation temperature, growing the sample on the substrate, and turning off the laser after the growth is completed;

[0014] 7) After the film growth is completed, the substrate sample holder is transferred to the four-dimensional sample stage, and the second infrared laser is turned on to anneal the back side of the substrate sample holder to obtain a higher quality film.

[0015] To achieve the above-mentioned purpose and other related purposes, the present invention also provides a device for preparing thin films by infrared laser heating, the device comprising a vacuum thin film growth chamber, a source material evaporation table, a substrate sample and a first infrared laser; the source material evaporation table and the substrate sample holder are respectively arranged in the vacuum thin film growth chamber; the first infrared laser is used for radiation heating of the source material and / or the substrate; the source material evaporation table comprises a crucible, the inner diameter of the crucible is larger than the diameter of the laser spot emitted by the first infrared laser.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides a method and device for preparing thin films by infrared laser heating, especially for some materials with high surface emissivity, using an infrared laser to directly radiate and heat the source material, and obtaining a high-quality thin film by adjusting the growth temperature, growth time and substrate annealing temperature. It can achieve layer-by-layer growth regulation, high growth efficiency, large size of the grown film, simple equipment, low price, and has great industrial application prospects. Compared with traditional thermal evaporation, this method can effectively shorten the heating and cooling time during the evaporation process, as well as the time required for degassing before evaporation, and the replacement of the source material does not need to destroy the cavity vacuum, which significantly improves the efficiency of thin film growth. Compared with PLD, there is no need to prepare a specific target material, and high-purity powder samples can be used after compacting. The crucible is made of a material with low surface emissivity, and no cooling device is required when the heat exchange efficiency between the crucible and the source material is low. This method is more advantageous for oxide materials with a high melting point.

[0018] Furthermore, the present invention can be flexibly adapted to various vacuum thin film growth chambers, and adding materials is convenient and quick. It is suitable for ultra-high vacuum, high vacuum, different atmospheres and other environments, and the device used is low in cost and easy to obtain and maintain.

[0019] Furthermore, the present invention can realize scanning evaporation in combination with a mechanical device to obtain high-quality large-area thin films, meeting the needs of industrial thin film growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a schematic diagram of the thin film growth method of the present invention.

[0021] Figure 2 It is a schematic diagram showing the structure of the source material evaporation table of the present invention.

[0022] Figure 3 Shown is a schematic diagram of the structure of the device for preparing thin films by infrared laser heating according to the present invention.

[0023] Figure 4 Shown is CeO grown on Au(111) for 30 minutes 2 Scanning tunneling microscope image of CeO 2 The coverage is 94.03% and the image size is 100nm×100nm.

[0024] Figure 5 Shown is CeO grown on Au(111) for 20 minutes 2 Scanning tunneling microscope image of CeO 2 The coverage is 74.53% and the image size is 47nm×47nm.

[0025] Figure 6 Shown is a monolayer CeO grown on Cu(111)2 Scanning tunneling microscope image of CeO grown on Cu(111). 2 The evaporation time was 10 min. The large-scale scanning tunneling microscopy image shows a single layer of CeO 2 Island. Image size 48nm×48nm.

[0026] Figure 7 Growth of CeO monolayer on Cu(111) 2 The scanning tunneling microscope image can clearly see the atomic resolution. The image size is 13nm×13nm.

[0027] Figure 8 Shown is a schematic diagram of the structure of the base sample holder.

[0028] In the figure:

[0029] 1 Vacuum thin film growth chamber

[0030] 2 Source material evaporation station

[0031] 21 Source material sample holder

[0032] 22 Crucible

[0033] 3 Substrate sample holder

[0034] 31 Gasket

[0035] 32 Fasteners

[0036] 4 The first infrared laser

[0037] 5 The first high temperature thermometer

[0038] 6 Second high temperature thermometer

[0039] 7 Second infrared laser

[0040] 8 Robot

[0041] 9 Four-dimensional sample platform

[0042] 10 First through hole

[0043] 11 Second through hole

[0044] 12 Third through hole

[0045] 13 Fourth through hole

[0046] 14 Fifth through hole

[0047] 15 Sixth through hole DETAILED DESCRIPTION

[0048] The following describes in detail an embodiment of a method and device for preparing a thin film by infrared laser heating.

[0049] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0051] The present invention relates to a method and device for realizing controllable epitaxial growth of thin films by heating source materials through laser radiation. The present invention utilizes infrared laser radiation to heat source materials, mainly targeting materials with high surface emissivity, such as oxide ceramics (cerium oxide, etc.), semiconductor oxides (titanium dioxide, etc.), ferroelectric materials (iron tetroxide, strontium titanate, etc.), etc.; the main designed devices include a vacuum system, a first infrared laser 4 and a second infrared laser 7, a first high-temperature thermometer 5 and a second high-temperature thermometer 6, a source material evaporation table 2 and a crucible 22, a substrate sample holder 3, etc., and optionally a fast sample injection cavity. The device used in the present invention has low cost, convenient installation, and is flexibly adapted to various vacuum thin film growth chambers 1, suitable for various ultra-high vacuum, high vacuum or gas-introduced environments, with high growth efficiency, controllable film thickness, and high quality. The source material evaporation table 2 and the crucible 22 are small in size and do not require a cooling device, which greatly shortens the degassing time of the evaporation source; the laser heating has a fast heating rate, and can quickly reach the temperature required for the evaporation of the source material; the layer-by-layer growth of the thin film can be regulated by adjusting the laser power and the heating time. The disadvantages of molecular beam epitaxy (MBE), such as long degassing and evaporation time and low growth efficiency, and the disadvantages of pulsed laser deposition (PLD), such as many defects in film growth and mostly three-dimensional growth, are optimized. The present invention can realize scanning evaporation in combination with a mechanical device to obtain high-quality large-area films, meeting the needs of industrial film growth. On this basis, the present invention is completed.

[0052] <Method for preparing thin film by infrared laser heating>

[0053] The present invention also provides a method for preparing a thin film by infrared laser heating, the method comprising heating a source material in a vacuum thin film growth chamber 1 by an external first infrared laser 4 to evaporate and deposit the material onto a substrate to obtain a thin film.

[0054] In the infrared laser heating method for preparing thin films provided by the present invention, the vacuum thin film growth chamber 1 can be evacuated using a dry pump, a molecular pump, or an ion pump to obtain a high vacuum or ultra-high vacuum environment, or can be passed with oxygen or the like to maintain the desired atmosphere. The vacuum thin film growth chamber 1 is preferably an ultra-high vacuum thin film growth chamber. The vacuum environment of the vacuum thin film growth chamber 1 is 1×10 -7 ~1×10 -12 mbar.

[0055] In the infrared laser heating method for preparing a thin film provided by the present invention, the laser spot diameter of the first infrared laser 4 is smaller than the diameter of the source material. In some embodiments, the laser spot diameter of the first infrared laser 4 can be, for example, about 3 mm to 10 mm. Further optionally, the laser spot diameter of the first infrared laser 4 can be, for example, about 3 mm to 6 mm or 6 mm to 10 mm. Preferably, it is 3 mm to 6 mm. The laser wavelength of the first infrared laser 4 can select the wavelength of the highest absorption spectrum according to the infrared absorption spectrum of the evaporation source material.

[0056] In the infrared laser heating method for preparing a thin film provided by the present invention, the source material is selected from one of powder, crystal particles, and target material. Optionally, when the source material is powder or crystal particles, the source material is placed in the crucible 22 of the source material evaporation table 2 and compacted. When the source material is a target material, the target material is welded to the sample holder.

[0057] In the infrared laser heating method for preparing a thin film provided by the present invention, the source material is a high surface emissivity material, or the source material can be converted into a high surface emissivity material after heating. Optionally, the ε of the high surface emissivity material is greater than 0.7. Preferably, the ε of the high surface emissivity material is 0.7-0.9. In the present invention, the applicable source material requires a high surface emissivity, and the wavelength of the infrared laser emission laser is preferably adapted to the source material to obtain a higher heating efficiency. Taking the commonly used infrared laser (central wavelength 1064nm, 915nm) as an example, for example, one or more selected from oxide ceramics, semiconductor oxides, and ferroelectric materials. Among them, oxide ceramics such as cerium oxide, etc. Semiconductor oxides such as titanium dioxide, etc. Ferroelectric materials such as ferroferric oxide, strontium titanate, etc.

[0058] In the infrared laser heating method for preparing a thin film provided by the present invention, the substrate is a single crystal substrate, a cleaved substrate, or a SrTiO 3 , KTaO 3 Optionally, the single crystal substrate may be, for example, Au single crystal, Cu single crystal, Si single crystal, etc. The cleaved substrate may be, for example, HOPG, etc.

[0059] The substrate can also be cleaned by chemical methods outside the vacuum thin film growth chamber 1 to obtain a clean surface (such as SrTiO 3 , KTaO 3This is done before placing the substrate into the vacuum film growth chamber 1; or a cleaved substrate (such as HOPG, etc.) can be used, or an argon ion sputtering annealing treatment of a single crystal substrate (such as Au single crystal, Cu single crystal, Si single crystal, etc.) can be used. This treatment method is performed in a vacuum environment. Specifically, when using argon ion sputtering annealing to treat Au (111) single crystal or Cu (111) single crystal substrate, for example, the argon ion gun parameters can be 1 KeV 10 mA and the argon atmosphere is 5.0×10 -6 The single crystal substrate was sputtered for 20 min under the condition of less than 1×10 -9 In a vacuum environment of mbar, the back surface is heated to 400°C using a laser for annealing for 30 minutes. This is repeated several times to obtain a clean single crystal substrate.

[0060] In the infrared laser heating method for preparing a thin film provided by the present invention, the distance between the source material and the substrate is 2 to 15 cm. Optionally, the distance between the source material and the substrate can be, for example, 2 to 10 cm, 2 to 6 cm, 6 to 10 cm, or 10 to 15 cm. In some embodiments, the source material is disposed at the center of the vacuum thin film growth chamber 1.

[0061] In the infrared laser heating method for preparing a thin film provided by the present invention, the substrate is placed within the evaporation angle of the source material, and the angle is the angle between the substrate and the normal line of the evaporation table plane, ranging from 0 to 70°. Optionally, the evaporation angle range can be, for example, 0 to 20°, 20 to 40°, 40 to 70°, etc.

[0062] In the infrared laser heating method for preparing a thin film provided by the present invention, the evaporation temperature is 450° C. to 1300° C. Optionally, the evaporation temperature may be, for example, 450° C. to 600° C., 600° C. to 800° C., 800° C. to 1000° C. or 1000° C. to 1300° C.

[0063] In the infrared laser heating method for preparing a thin film provided by the present invention, in some embodiments, the source material is placed on a source material evaporation table 2, and the substrate is placed on a substrate sample holder 3. Before evaporation and deposition, the source material evaporation table 2, the source material, the substrate, and the substrate sample holder 3 need to be degassed as a whole.

[0064] Optionally, the vacuum during the entire degassing process should be less than 5 × 10 -8 mbar, when the vacuum is kept constant at the evaporation temperature of the source material, the degassing can be ended, generally less than 2×10 -9 mbar. This is used in ultra-high vacuum environments, such as 1×10 -9 ~1×10 -12 mbar vacuum environment.

[0065] Typically, one infrared laser or two infrared lasers may be used. Optionally, the first infrared laser 4 or the second infrared laser 7 is adjusted to focus on the back of the substrate sample holder 3, and the first infrared laser 4 or the second infrared laser 7 is turned on to heat and degas the substrate and the sample holder.

[0066] Optionally, the first infrared laser 4 is adjusted to focus on the back of the source material evaporation table 2 and the source material, respectively, and the first infrared laser 4 is turned on to heat the back of the source material evaporation table 2 and the source material, respectively, to perform a rapid degassing process.

[0067] In the infrared laser heating method for preparing a thin film provided by the present invention, the laser spot of the second infrared laser 7 matches the size of the substrate. Optionally, the laser spot of the second infrared laser 7 is 5 mm to 10 mm.

[0068] In the infrared laser heating method for preparing a thin film provided by the present invention, after the thin film is grown, the first infrared laser 4 or the second infrared laser 7 is turned on to anneal the back side of the substrate sample holder 3. The annealing temperature may be, for example, 25°C to 600°C. Alternatively, the annealing temperature may be, for example, 25°C to 100°C, 100°C to 300°C, or 300°C to 600°C.

[0069] In a specific embodiment, the preparation method comprises the following steps:

[0070] 1) placing the source material in the crucible 22 of the source material evaporation table 2 and compacting it, and placing the substrate on the substrate sample holder 3;

[0071] 2) placing a source material evaporation table 2 containing source materials and a substrate sample holder 3 containing substrates into a vacuum thin film growth chamber 1;

[0072] 3) adjusting the first infrared laser 4 or the second infrared laser 7 to focus on the back of the substrate sample holder 3, turning on the first infrared laser 4 or the second infrared laser 7 to heat and degas the substrate and the sample holder, the degassing temperature is determined by the annealing temperature required for the substrate, and turning off the laser after the degassing is completed;

[0073] 4) adjusting the first infrared laser 4 to focus on the back of the source material evaporation table 2 and the source material respectively, turning on the first infrared laser 4 to heat the back of the source material evaporation table 2 and the source material respectively, and performing a rapid degassing process. The degassing temperature is determined by the required evaporation temperature of the source material. After the degassing is completed, the laser is turned off;

[0074] 5) Place the source material evaporation table 2 at the center of the growth chamber, and place the substrate sample holder 3 facing the source material evaporation table 2, with a distance of 2-10 cm between the source material and the substrate;

[0075] 6) adjusting the first infrared laser 4 to focus on the source material in the source material evaporation table 2, turning on the first infrared laser 4 to heat the source material to the evaporation temperature, growing the sample on the substrate, and turning off the laser after the growth is completed;

[0076] 7) After the film growth is completed, the first infrared laser 4 or the second infrared laser 7 is turned on to focus on the back side of the substrate sample holder 3 to anneal the substrate to obtain a higher quality film.

[0077] In the aforementioned step 2), the source material evaporation table 2 containing the source material and the substrate sample holder 3 containing the substrate can also be placed in the fast sampling chamber first, evacuated to obtain the required sample transfer vacuum, and then the source material evaporation table 2 and the substrate sample holder 3 are transferred into the vacuum thin film growth chamber 1.

[0078] Furthermore, the vacuum of the vacuum thin film growth chamber 1 is better than the vacuum of the fast injection chamber.

[0079] Furthermore, the rapid injection chamber and the vacuum film growth chamber 1 are evacuated by a mechanical pump-molecular pump group, and the background vacuum of the vacuum film growth chamber 1 reaches 3×10 -10 mbar. The vacuum value of the fast injection chamber is less than 2×10 -8 mbar, the plug valve between the fast sample injection chamber and the ultra-high vacuum chamber is opened to transfer the source material evaporation table 2 and the substrate sample holder 3 into the ultra-high vacuum chamber.

[0080] The new method of the present invention is mainly aimed at materials with high surface emissivity; the method uses infrared laser radiation to heat the surface of the source material for evaporation, concentrates heat energy, and accurately controls the surface temperature of the material to control the amount and shape of evaporated atoms or atomic clusters, and synergistically controls the growth time to achieve the purpose of layer-by-layer growth; the method can be regarded as a point evaporation source (the laser focusing spot of the semiconductor infrared laser is 3mm-10mm, and the diameter of the circle is 5mm in the embodiment), the evaporation angle is large, spherical, and non-focusing, and the growth rate can be controlled by controlling the distance from the evaporation source. By designing a multi-sample stage, multiple substrates can be grown simultaneously, and by designing a multi-evaporation stage-laser group heating, multiple sources can be evaporated and grown simultaneously. Multi-compound thin films; the method has fast heating and cooling rates and short degassing time, which can significantly reduce the time required for thin film growth; the source material replacement of the method does not need to destroy the vacuum environment of the cavity, and the growth of thin films of different materials can be quickly switched by fast injection into the cavity; the source material evaporation table 2 and the crucible 22 of the method are simple, and the cooling device is not necessary when the thermal conductivity is poor, and it is easy to modify and adapt to various cavities.

[0081] The method for preparing thin films by infrared laser heating of the present invention can be carried out using the following device for preparing thin films by infrared laser heating.

[0082] <Device for preparing thin films by infrared laser heating>

[0083] The present invention provides a device for preparing thin films by infrared laser heating, such as Figure 3 The device includes a vacuum thin film growth chamber 1, a source material evaporation table 2, a substrate sample holder 3 and a first infrared laser 4; the source material evaporation table 2 and the substrate sample holder 3 are respectively arranged in the vacuum thin film growth chamber 1; the first infrared laser 4 is used for radiation heating of the source material and / or the substrate; the source material evaporation table 2 includes a crucible 22, and the inner diameter of the crucible 22 is larger than the diameter of the laser spot emitted by the first infrared laser 4.

[0084] In the device for preparing thin films by infrared laser heating provided in the present application, the vacuum thin film growth chamber 1 can provide growth environments such as ultra-high vacuum, high vacuum, and different atmospheres for thin film growth.

[0085] In the device for preparing thin films by infrared laser heating provided in the present application, Figure 2 The source material evaporation stage 2 includes a source material sample holder 21 and a crucible 22 disposed on the source material sample holder 21 .

[0086] In some embodiments, the source material evaporation table 2 can be optionally shaped by relying on a sample transfer device (such as a sample transfer rod), and the core structure is a crucible 22 that can be filled with source materials. Figure 2 In some embodiments, the crucible 22 is a circular groove crucible 22, and the inner diameter of the crucible 22 is larger than the spot diameter of the first infrared laser 4. Optionally, the laser spot diameter of the first infrared laser 4 is 3 mm to 10 mm, and further optionally, the laser spot diameter of the first infrared laser 4 can be, for example, about 3 mm to 6 mm or 6 mm to 10 mm. Preferably, it is 3 mm to 6 mm. More preferably, it is 5 mm.

[0087] In some embodiments, the crucible 22 is placed at the center of the vacuum thin film growth chamber 1 , and the first infrared laser 4 can be adjusted to focus on the source material filled in the circular groove crucible 22 for local and rapid heating.

[0088] In some embodiments, the laser wavelength of the first infrared laser 4 can be selected from the wavelength of the highest absorption spectrum according to the infrared absorption spectrum of the evaporation source material.

[0089] In some embodiments, optionally, the crucible 22 is used to place the source material and perform direct radiation heating. The material of the source material evaporation table 2 is a high temperature resistant low surface emissivity material. The material can be steel (such as 304 steel), molybdenum or other high temperature resistant low surface emissivity materials. Other high temperature resistant low surface emissivity materials can be, for example, tantalum, alloy materials, etc. The source material placed inside can be, for example, a material with high surface emissivity, such as oxide ceramics (cerium oxide, etc.), semiconductor oxides (titanium dioxide, etc.), ferroelectric materials (iron tetroxide, strontium titanate, etc.), etc.

[0090] In some embodiments, the source material sample holder 21 is a flag-type sample holder, which is the most widely used type of sample holder in ultra-high vacuum surface analysis laboratories.

[0091] In some embodiments, the first infrared laser 4 uses a laser with a laser wavelength of 912 nm. The source material has a high laser absorption, and the source material filled in the crucible 22 can be quickly heated.

[0092] In a specific embodiment, the source material sample holder 21 and the crucible 22 are integrally formed.

[0093] In the device for preparing thin films by infrared laser heating provided in the present application, Figure 8 , the substrate sample holder 3 is used to place the substrate. The substrate sample holder 3 is a detachable sample holder, and the detachable structure can quickly and conveniently replace different substrates. Figure 8 , the base sample holder 3 is provided with a plurality of gaskets 31, and the plurality of gaskets 31 are enclosed to form a square. Usually, the base is provided between the gaskets 31 and the base sample holder 3, and each gasket 31 and the base sample holder 3 are fixed by a fastener 32. Specifically, for example, the base can be fixed by a nut.

[0094] In some embodiments, the plane of the substrate sample holder 3 faces the source material evaporation stage 2. The distance between the center of the substrate sample holder 3 and the source material evaporation stage 2 is 2-15 cm. Optionally, the distance between the center of the substrate sample holder 3 and the source material evaporation stage 2 can be, for example, 2-10 cm, 2-6 cm, 6-10 cm, or 10-15 cm.

[0095] In the device for preparing thin films by infrared laser heating provided in the present application, Figure 3 The vacuum thin film growth chamber 1 has a first through hole 10 on its wall, and also includes a four-dimensional sample platform 9, which is connected to the vacuum thin film growth chamber 1 through the first through hole 10. The four-dimensional sample platform 9 can be used to place the source material evaporation table 2 or the substrate sample holder 3. The four-dimensional sample platform 9 is used to adjust the position of the source material evaporation table 2 or the substrate sample holder 3 in the vacuum thin film growth chamber 1. The adjustment direction can be in the X direction, the Y direction, the Z direction or can be rotated. The four-dimensional platform manufacturer can be, for example, VACGEN, the model is WX611015HH, and the country of production is the United Kingdom.

[0096] In some embodiments, such as Figure 3, a second through hole 11 is provided on the cavity wall of the vacuum cavity, and the device further comprises a manipulator 8, wherein the manipulator 8 is connected to the vacuum thin film growth cavity 1 through the second through hole 11, and the manipulator 8 passes through the first through hole 10 to grab the sample holder, and the manipulator 8 is perpendicular to the four-dimensional sample platform 9. The manipulator 8 (adjustable at ±22.5°) grabs the substrate sample holder 3 and the source material evaporation table 2 and facilitates the adjustment of the growth position of the substrate. The connection mode of the manipulator 8 to the substrate sample holder 3 or the source material evaporation table 2 is grabbing or placing. In some embodiments, the brand of the manipulator 8 may be, for example, FERMI, the model is WS35L150, and the country of manufacture is China.

[0097] In the device for preparing thin films by infrared laser heating provided in the present application, the first infrared laser 4 is used for radiation heating of the source material, and the angle between the laser direction of the first infrared laser 4 and the normal line on the plane of the source material evaporation table 2 is less than 45° to avoid cross interference with the substrate. Normally, the light reflected by the first infrared laser 4 cannot hit the first high-temperature thermometer 5, the second high-temperature thermometer 6, the second infrared laser 7, and the substrate sample holder 3.

[0098] Alternatively, if Figure 3 The wall of the vacuum thin film growth chamber 1 is provided with a third through hole 12, and the laser of the first infrared laser 4 passes through the third through hole 12 to focus on the source material in the source material evaporation stage 2 and perform radiation heating. In some embodiments, the brand of the first infrared laser 4 can be, for example, Beijing Honglan Optoelectronics, the model is VCL915nmLNE2, and the country of manufacture is China.

[0099] The first infrared laser 4 is directly focused on the surface of the source material to directly radiate and heat the source material. The temperature of the crucible 22 depends only on the heat conduction efficiency of the source material. When the heat conduction efficiency is low, no cooling device is required.

[0100] In the device for preparing thin films by infrared laser heating provided in the present application, Figure 3 The device further comprises a first high temperature thermometer 5 for measuring the temperature of the surface of the source material and performing temperature monitoring during the thin film growth process. Optionally, a fourth through hole 13 is provided on the cavity wall of the vacuum thin film growth cavity 1, and the infrared light emitted by the source material passes through the fourth through hole 13 and is detected by the first high temperature thermometer 5. In some embodiments, the brand of the first high temperature thermometer 5 can be, for example, LUMASENSE, the model is IGA6 / 23, and the country of manufacture is China.

[0101] In the device for preparing thin films by infrared laser heating provided in the present application, Figure 3, the device also includes a second infrared laser 7 for back heating of the substrate. Optionally, a fifth through hole 14 is provided on the cavity wall of the vacuum thin film growth cavity 1, and the laser of the second infrared laser 7 passes through the fifth through hole 14 and focuses on the back side of the substrate sample holder 3 for heating. In some embodiments, the laser spot diameter of the second infrared laser 7 is 5mm to 10mm. The brand of the second infrared laser 7 can be, for example, Beijing Honglan Optoelectronics, the model is VCL915nmLNE2, and the country of production is China.

[0102] In the device for preparing thin films by infrared laser heating provided in the present application, Figure 3 The device further includes a second high-temperature thermometer 6, which is used to measure the temperature of the substrate or the sample in the substrate, and monitor the temperature during the film growth process or the annealing after the film growth. Optionally, a sixth through hole 15 is provided on the cavity wall of the vacuum cavity, and the infrared light emitted by the substrate or the sample in the substrate passes through the sixth through hole 15 and is detected by the second high-temperature thermometer 6. In some embodiments, the brand of the second high-temperature thermometer 6 can be, for example, LUMASENSE, the model is IGA6 / 23, and the country of production is China.

[0103] Working principle of the device for preparing thin film by infrared laser heating provided in this application:

[0104] like Figure 2 , the source material is placed in the crucible 22 of the source material evaporation station 2 and compacted, as Figure 8 , place the substrate between the gasket 31 and the substrate sample holder 3, and fix and compact them with nuts. Figure 3 A manipulator 8 is used to grab the source material evaporation table 2 and place it on the four-dimensional sample platform 9, and the source material evaporation table 2 is adjusted to a suitable position in the vacuum chamber through the four-dimensional sample platform 9, and then the manipulator 8 is used to clamp the substrate sample holder 3, and the substrate sample holder 3 is adjusted to a suitable position by rotating the manipulator 8, and then the source material is radiantly heated by the first infrared laser 4, the surface temperature of the source material is monitored by the first high-temperature thermometer 5, the substrate is back-heated by the second infrared laser 7, and the temperature of the substrate or the sample in the substrate is measured by the second high-temperature thermometer 6.

[0105] The beneficial effects of the present invention are further illustrated below in conjunction with embodiments.

[0106] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with examples. However, it should be understood that the examples of the present invention are only for explaining the present invention, not for limiting the present invention, and the examples of the present invention are not limited to the examples given in the specification. The specific experimental conditions or operating conditions not specified in the examples are made under conventional conditions, or are made under the conditions recommended by the material supplier.

[0107] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0108] In the following examples, the reagents, materials and instruments used are all commercially available unless otherwise specified.

[0109] The device and method mentioned in the above invention are described in more detail through examples. This example is only a part of the application cases that have been obtained in the laboratory. It aims to clarify the advantages of the patent of the present invention. Compared with the two commonly used thin film growth technologies, it can obtain high-quality thin films more efficiently and conveniently, and regulate the layer-by-layer growth of thin film samples.

[0110] Embodiment 1:

[0111] CeO 2 The growth on Au (111) is used as an example, using a 915 nm infrared band semiconductor laser (a first infrared laser 4 and a second infrared laser 7), and the detailed steps are as follows:

[0112] 1. CeO with a purity of 99.9% 2 The powder is placed in the crucible 22 of the source material evaporation station 2 and compacted;

[0113] 2. Fix the Au (111) single crystal on the base sample holder 3;

[0114] 3. Place the CeO 2 The source material evaporation table 2 and Au(111) are simultaneously placed in the fast sample injection chamber of the ultra-high vacuum system, and vacuum is evacuated using a mechanical pump and a molecular pump;

[0115] 4. Rapid injection chamber vacuum is less than 2×10 -8 mbar, open the gate valve between the fast sample injection chamber and the vacuum film growth chamber 1, and inject the CeO 2 The source material of the evaporation station 2 and Au(111) were transferred to a vacuum of less than 3×10 -10mbar vacuum thin film growth chamber 1;

[0116] 5. Use the second infrared laser 7 to heat the Au(111) backing to 430°C for degassing. The vacuum is kept less than 2×10 -9 mbar, vacuum less than 5×10 -10 mbar, the degassing is finished;

[0117] 6. The parameters of the argon ion gun are 1KeV 10mA and the argon pressure is 5.0×10 -6 Au(111) was sputtered for 20 min at a temperature less than 1×10 -9 The Au(111) backing was heated to 400°C and annealed for 30 min using a second infrared laser 7 in a vacuum environment of mbar;

[0118] 7. Repeat step 6 twice to obtain a clean Au(111) surface;

[0119] 8. Focus the first infrared laser 4 spot onto the CeO in the crucible 22 of the source material evaporation station 2. 2 On the other hand, turning on the first infrared laser 4 can accurately heat the CeO on the inner surface of the crucible 22. 2 The sample is heated to 1100°C for rapid degassing. The vacuum is maintained at less than 1×10 -8 mbar, vacuum less than 5×10 -9 mbar, the degassing is finished (it takes about 150 minutes, and the degassing time of the MBE method is usually more than 72 hours);

[0120] 9. According to Figure 1 As shown, CeO can be adjusted as needed 2 The growth distance between Au(111) is 2 cm.

[0121] 10. According to Figure 1 The film growth is performed as shown in the figure, and the CeO is rapidly heated by the first infrared laser 4. 2 CeO grown on Au(111) at 1050°C (within 20 minutes, MBE heating time required more than 60 minutes) 2 Thin film, control the growth time as needed;

[0122] 11. The grown Au(111) was annealed at 300℃ for 10min to obtain high quality CeO 2 film.

[0123] like Figure 4 and 5 ,in Figure 4 CeO was grown on Au(111) for 30 min.2 Scanning tunneling microscope image of CeO 2 The coverage is 94.03%, the image size is 100nm×100nm, CeO 2 The film thickness is 4.6 angstroms. Figure 5 To grow CeO on Au(111) for 20 min 2 Scanning tunneling microscope image, through the scanning tunneling microscope image, we can see CeO 2 The coverage reaches 74.53%, CeO 2 The CeO 2 The film thickness is 4 angstroms.

[0124] Embodiment 2:

[0125] CeO 2 Growth on Cu (111) is used as an example, using a 915 nm infrared band semiconductor laser (a first infrared laser 4 and a second infrared laser 7), and the detailed steps are as follows:

[0126] 1. CeO with a purity of 99.9% 2 The powder is placed in the crucible 22 of the source material evaporation station 2 and compacted;

[0127] 2. Fix the Cu(111) single crystal on the base sample holder 3;

[0128] 3. Place the CeO 2 The source material evaporation table 2 and Cu(111) are simultaneously placed in the fast sample injection chamber of the ultra-high vacuum system, and vacuum is evacuated using a mechanical pump and a molecular pump;

[0129] 4. Rapid injection chamber vacuum is less than 2×10 -8 mbar, open the gate valve between the fast sample injection chamber and the vacuum film growth chamber 1, and inject the CeO 2 The source material of the evaporation station 2 and Cu(111) were transferred to a vacuum of less than 3×10 -10 mbar vacuum thin film growth chamber 1;

[0130] 5. Use the second infrared laser 7 to heat the Cu(111) backing to 430°C for degassing. The vacuum is kept less than 2×10 -9 mbar, vacuum less than 5×10 -10 mbar, the degassing is finished;

[0131] 6. The parameters of the argon ion gun are 1KeV 10mA and the argon pressure is 5.0×10 -6 mbar, Cu(111) was sputtered for 20 min. -9The Cu(111) backing was heated to 400°C and annealed for 30 min using a second infrared laser 7 in a vacuum environment of mbar;

[0132] 7. Repeat step 6 twice to obtain a clean Cu(111) surface;

[0133] 8. Focus the first infrared laser 4 spot onto the CeO in the crucible 22 of the source material evaporation station 2. 2 On the other hand, turning on the first infrared laser 4 can accurately heat the CeO on the inner surface of the crucible 22. 2 The sample is heated to 1100°C for rapid degassing. The vacuum is maintained at less than 1×10 -8 mbar, vacuum less than 5×10 -9 mbar, the degassing is finished (it takes about 150 minutes, and the degassing time of the MBE method is usually more than 72 hours);

[0134] 9. According to Figure 1 As shown, CeO can be adjusted as needed 2 The growth distance between Cu(111) is 2 cm.

[0135] 10. According to Figure 1 The film growth is performed as shown in the figure, and the CeO is rapidly heated by the first infrared laser 4. 2 CeO grown on Cu(111) at 1050°C (less than 20 minutes, MBE heating time is more than 60 minutes) 2 Thin film, control the growth time as needed;

[0136] 11. The grown Cu(111) was annealed at 300℃ for 10min to obtain high quality CeO 2 film.

[0137] like Figure 6 CeO grown on Cu(111) 2 The evaporation time was 10 min. The large-scale scanning tunneling microscopy image shows a single layer of CeO 2 Island; CeO 2 The thickness of the film is 0.5 angstroms. Figure 7 The monolayer CeO grown on Cu(111) 2 Scanning tunnelling microscope images can clearly see atomic resolution.

[0138] The above embodiments describe that CeO 2 Taking growth as an example, a new method and device for preparing thin films is provided. By adjusting the temperature of the evaporation source material, the distance between the source material and the substrate, the evaporation time, etc., the rapid layer-by-layer growth of the thin film can be controlled, with high growth efficiency and high film quality.

[0139] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a thin film by infrared laser heating, characterized in that: The method comprises heating a source material in a vacuum thin film growth chamber (1) by an external first infrared laser (4) to evaporate and deposit the source material onto a substrate to obtain a thin film.

2. The method for preparing a thin film by infrared laser heating according to claim 1, characterized in that: Also includes any one or more of the following features: A1) The vacuum environment of the vacuum thin film growth chamber (1) is 1×10 -7 ~1×10 -12 mbar; A2) the laser spot diameter of the first infrared laser (4) is smaller than the diameter of the source material; A3) the source material is selected from one of powder, crystal particles and target material; A4) the source material is a high surface emissivity material, or the source material can be converted into a high surface emissivity material after heating; A5) the substrate is one of a single crystal substrate and a cleaved substrate; A6) the distance between the source material and the substrate is 2 to 15 cm; A7) the substrate is placed within the evaporation angle of the source material, where the angle is the angle between the substrate and the normal line of the evaporation table plane, ranging from 0° to 70°; A8) the evaporation temperature is 450°C to 1300°C; A9) placing the source material on a source material evaporation table (2), and placing the substrate on a substrate sample holder (3). Before evaporation deposition, the source material evaporation table (2), the source material, the substrate, and the substrate sample holder (3) need to be degassed as a whole.

3. The method for preparing a thin film by infrared laser heating as claimed in claim 2, characterized in that: Also includes any one or more of the following features: A21) In feature A2), the laser spot diameter of the first infrared laser (4) is about 3 mm to 10 mm; A31) In feature A3), when the source material is a powder or crystal particles, the source material is placed in a crucible (22) of a source material evaporation table (2) and compacted; A32) In feature A3), when the source material is a target material, the target material is welded to the sample holder; A41) The ε of the high surface emissivity material is greater than 0.7; A61) In feature A6), the distance between the source material and the substrate is 2-10 cm; A91) In feature A9), the vacuum during the entire degassing process is less than 5×10 -8 mbar, when the evaporation temperature of the source material is reached and the vacuum is kept constant, the degassing can be ended. When the vacuum is kept constant, it is preferably less than 2×10 -9 mbar; A92) In feature A9), the first infrared laser (4) or the second infrared laser (7) is adjusted to focus on the back side of the substrate sample holder (3), and the first infrared laser (4) or the second infrared laser (7) is turned on to heat and degas the substrate and the sample holder; A93) In feature A9), the first infrared laser (4) is adjusted to focus on the back of the source material evaporation table (2) and the source material respectively, and the first infrared laser (4) is turned on to heat the back of the source material evaporation table (2) and the source material respectively to perform a rapid degassing process.

4. The method for preparing a thin film by infrared laser heating as claimed in claim 3, characterized in that: Also includes any one or more of the following features: A211) In feature A21), the laser spot diameter of the first infrared laser (4) is about 3 mm to 6 mm; A411) In feature A41), the ε of the high surface emissivity material is 0.7 to 0.9; A921) In feature A92), the laser spot of the second infrared laser (7) matches the size of the substrate.

5. The method for preparing a thin film by infrared laser heating as claimed in claim 4, characterized in that: The laser spot of the second infrared laser (7) is 5 mm to 10 mm.

6. The method for preparing a thin film by infrared laser heating as claimed in claim 3, characterized in that: After the film growth is completed, the first infrared laser (4) or the second infrared laser (7) is turned on to perform annealing on the back side of the substrate sample holder (3); the annealing temperature is 25°C to 600°C.

7. An infrared laser heating device for preparing thin films, characterized in that: The device comprises a vacuum thin film growth chamber (1), a source material evaporation table (2), a substrate sample holder (3) and a first infrared laser (4); the source material evaporation table (2) and the substrate sample holder (3) are respectively arranged in the vacuum thin film growth chamber (1); the first infrared laser (4) is used for radiation heating of the source material and / or the substrate; the source material evaporation table (2) comprises a crucible (22), the inner diameter of the crucible (22) being larger than the diameter of the laser spot emitted by the first infrared laser (4).

8. The device for preparing thin films by infrared laser heating as claimed in claim 7, characterized in that: Also includes any one or more of the following features: B1) the source material evaporation table (2) further comprises a source material sample holder (21), and the crucible (22) is arranged on the source material sample holder (21); B2) the crucible (22) is arranged at the center of the vacuum thin film growth chamber (1); B3) The source material evaporation table (2) is made of a high temperature resistant and low surface emissivity material.

9. The device for preparing thin films by infrared laser heating as claimed in claim 7, characterized in that: Also includes any one or more of the following features: C1) the flat surface of the substrate sample holder (3) faces the source material evaporation table (2); C2) the distance between the center of the substrate sample holder (3) and the source material evaporation table (2) is 2-10 cm; C3) the angle between the laser direction of the first infrared laser (4) and the normal line on the plane of the source material evaporation table (2) is less than 45°; C4) The laser spot diameter of the first infrared laser (4) is 3 mm to 10 mm.

10. The device for preparing thin films by infrared laser heating as claimed in claim 7, characterized in that: Also includes any one or more of the following features: D1) A first through hole (10) is provided on the cavity wall of the vacuum thin film growth cavity (1), and the device further comprises a four-dimensional sample platform (9), wherein the four-dimensional sample platform (9) is connected to the vacuum thin film growth cavity (1) via the first through hole (10), and the four-dimensional sample platform (9) is used to adjust the position of the source material evaporation table (2) or the substrate sample holder (3) in the vacuum thin film growth cavity (1); D2) A second through hole (11) is provided on the cavity wall of the vacuum thin film growth cavity (1), and the device further comprises a manipulator (8), the manipulator (8) is connected to the vacuum thin film growth cavity (1) via the second through hole (11), the manipulator (8) is used to grab the sample holder, and the manipulator (8) and the four-dimensional sample platform (9) are perpendicular to each other; D3) a third through hole (12) is provided on the cavity wall of the vacuum thin film growth cavity (1), and the laser light of the first infrared laser (4) passes through the third through hole (12) to focus on the source material in the source material evaporation table (2) and perform radiation heating; D4) a fourth through hole (13) is provided on the wall of the vacuum thin film growth chamber (1), the device comprises a first high temperature thermometer (5), and the first high temperature thermometer (5) is used to measure the surface temperature of the source material; D5) a fifth through hole (14) is provided on the cavity wall of the vacuum thin film growth cavity (1), the device comprises a second infrared laser (7), and laser light from the second infrared laser (7) passes through the fifth through hole (14) and is focused on the back side of the substrate sample holder (3) for heating; D6) A sixth through hole (15) is provided on the wall of the vacuum thin film growth chamber (1), and the device comprises a second high-temperature thermometer (6), which is used to measure the temperature of the substrate or the sample in the substrate.

Images