Preparation method of thin film

Abstract

The invention provides a preparation method of a thin film, which comprises the following steps of: providing a substrate, and depositing a first layer of thin film on the substrate by adopting a chemical vapor deposition process; measuring the thicknesses of different positions of the first layer of film by using a measuring machine to obtain the thickness distribution of the first layer of film; dividing the first layer of film into a plurality of areas according to the thickness distribution; calculating the deposition time required by each area to be deposited to a target thickness by adopting an atomic layer deposition process; and sequentially depositing a second layer of film on the first layer of film in different areas according to the calculated deposition time by adopting an atomic layer deposition process. The method comprises the following steps: forming a first layer of film with a thin middle part and a thick edge by adopting a chemical vapor deposition process, and forming a second layer of film with different thicknesses on the first layer of film in different areas by adopting an atomic layer deposition process, so that the thickness uniformity of the film is improved; in addition, only the atomic layer deposition process is adopted to form the second layer of thin film, the time cost cannot be greatly increased, and the method is suitable for deposition of thin films with large film thicknesses.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor integrated circuits, and in particular to a thin film preparation method. BACKGROUND

[0002] Chemical vapor deposition (CVD) is a commonly used film formation technology for furnace tubes, but due to the limitations of the design of the furnace tube itself (for example, a diffusion type gas inlet method), the temperature and gas concentration in the center region of the wafer are relatively low, resulting in the center region of the finally formed thin film being relatively thin compared to the edge region, thereby affecting the overall thickness uniformity of the thin film.

[0003] Atomic layer deposition (ALD) is a film formation technology that uses alternately introduced precursors to perform chemical adsorption and reaction on the surface of a substrate, and only a single layer of atoms or molecules is deposited per cycle. Compared to chemical vapor deposition, the reaction gas of atomic layer deposition is no longer freely diffused from the tube, but is pressurized and injected from a vertical long nozzle to a specific location of the wafer, and uniform film thickness can be obtained by controlling the nozzle pressure.

[0004] However, compared to using chemical vapor deposition, using atomic layer deposition to deposit a thin film of the same thickness requires a significant increase in time cost, which is not suitable for scenarios with larger film thickness. SUMMARY

[0005] The purpose of the present application is to provide a thin film preparation method that can improve the uniformity of the thin film without significantly increasing the time cost.

[0006] To solve the above technical problems, the present application provides a thin film preparation method, comprising the following steps:

[0007] A substrate is provided, and a first layer of thin film is deposited on the substrate using a chemical vapor deposition process, the first layer of thin film being thinner in the middle than at the edges;

[0008] The thickness of the first layer of thin film at different positions is measured using a metrology machine, and the thickness distribution of the first layer of thin film is obtained;

[0009] The first layer of thin film is divided into multiple regions according to the thickness distribution;

[0010] The deposition time required to deposit each region to a target thickness using an atomic layer deposition process is calculated; and

[0011] A second layer of thin film is deposited on the first layer of thin film in different regions in sequence using an atomic layer deposition process according to the calculated deposition time.

[0012] Optionally, the method for calculating the deposition time required for each region to deposit to the target thickness using atomic layer deposition process comprises:

[0013] Calculating the average thickness of the first layer of film for each region;

[0014] According to the deposition rate collected by the atomic layer deposition machine and the average thickness, the deposition time required for each region to deposit to the target thickness is calculated.

[0015] Optionally, according to the thickness distribution, the first layer of film is divided into three regions: a central region, a sub-central region surrounding the central region, and an edge region surrounding the sub-central region.

[0016] Optionally, the thickness of the first layer of film in the edge region is equal to the target thickness.

[0017] Optionally, the second layer of film is sequentially deposited in the central region and the sub-central region using atomic layer deposition process, so that the sum of the thickness of the first layer of film and the second layer of film in each region on the substrate is equal to the target thickness.

[0018] Optionally, the thickness of the first layer of film in the edge region is less than the target thickness.

[0019] Optionally, the second layer of film is sequentially deposited in the central region, the sub-central region and the edge region using atomic layer deposition process, so that the sum of the thickness of the first layer of film and the second layer of film in each region on the substrate is equal to the target thickness.

[0020] Optionally, the atomic layer deposition process is completed in an atomic layer deposition machine, which comprises a furnace tube, a plurality of substrate supporting discs and a plurality of gas inlet pipes in the furnace tube, a plurality of nozzles are arranged on each gas inlet pipe, and the nozzles are used to spray gas to the substrates; the nozzles protrude from the gas inlet pipes, and the angle between the nozzles in each gas inlet pipe and the vertical direction is equal, and the angle between the nozzles in different gas inlet pipes and the vertical direction is different, so that different gas inlet pipes spray gas to different regions of the substrates.

[0021] Optionally, three gas inlet pipes are arranged in the furnace tube, including: a central region gas inlet pipe for spraying gas to the central region, a sub-central region gas inlet pipe for spraying gas to the sub-central region, and an edge region gas inlet pipe for spraying gas to the edge region; wherein the angle between the nozzles of the central region gas inlet pipe and the vertical direction is greater than the angle between the nozzles of the sub-central region gas inlet pipe and the vertical direction, and the angle between the nozzles of the sub-central region gas inlet pipe and the vertical direction is greater than the angle between the nozzles of the edge region gas inlet pipe and the vertical direction.

[0022] Optionally, the method for depositing the second layer of thin film on the center region by atomic layer deposition process comprises:

[0023] injecting precursor gas into the center region of the substrate by the center region gas inlet pipe, the precursor gas being adsorbed on the surface of the first layer of thin film;

[0024] injecting inert gas into the center region of the substrate by the center region gas inlet pipe to remove excess precursor gas;

[0025] injecting reaction gas into the center region of the substrate by the center region gas inlet pipe, the reaction gas reacting with the precursor gas to form an atomic layer;

[0026] repeating the above steps until the desired deposition time is performed to form the second layer of thin film on the first layer of thin film.

[0027] The method for preparing the thin film provided by the present application comprises the following steps: providing a substrate, depositing a first layer of thin film on the substrate by chemical vapor deposition process, the first layer of thin film being thick in the middle and thin at the edges; measuring the thickness of the first layer of thin film at different positions by a measurement machine, obtaining the thickness distribution of the first layer of thin film; dividing the first layer of thin film into multiple regions according to the thickness distribution; calculating the deposition time required for depositing the second layer of thin film on each region to the target thickness by atomic layer deposition process; and depositing the second layer of thin film on the first layer of thin film in different regions by atomic layer deposition process according to the calculated deposition time. The first layer of thin film is formed by chemical vapor deposition process, and the second layer of thin film with different thicknesses is formed on the first layer of thin film in different regions by atomic layer deposition process, so that the thickness uniformity of the thin film can be improved. In addition, the second layer of thin film is formed by atomic layer deposition process only, which does not significantly increase the time cost, and is suitable for the deposition of thin film with large thickness. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flowchart of the method for preparing the thin film provided by an embodiment of the present application.

[0029] Figures 2 to 5 is a structural diagram of each step of the method for preparing the thin film provided by an embodiment of the present application.

[0030] Figure 6 is a distribution diagram of each region of the first layer of thin film provided by an embodiment of the present application.

[0031] Figure 7 is a top view of the atomic layer deposition machine provided by an embodiment of the present application.

[0032] Figure 8is a schematic view of three gas inlets according to an embodiment of the present application.

[0033] Reference Signs List:

[0034] 10 - substrate; 11 - first layer of thin film; 12 - second layer of thin film; 20 - furnace tube; 21 - carrier disc; 22 - gas inlet; 22a - central region gas inlet; 22b - sub-central region gas inlet; 22c - edge region gas inlet; 23 - nozzle; 24 - exhaust port. DETAILED DESCRIPTION

[0035] As described in the background section, the thin film deposited by chemical vapor deposition process is thicker in the middle and thinner at the edges, and the film thickness is not uniform. Although the atomic layer deposition process can reduce the degree of film thickness non-uniformity, the time cost required for depositing the same thickness is greatly increased, which is not suitable for scenarios with larger film thickness.

[0036] To solve the above problems, the present application provides a method for preparing a thin film, which first deposits a first layer of thin film by chemical vapor deposition process, and then forms a second layer of thin film with different thicknesses on different regions of the first layer of thin film by atomic layer deposition process, thereby improving the thickness uniformity of the thin film, and at the same time, since only part of the thin film is deposited by atomic layer deposition process, the time cost is not greatly increased.

[0037] Specifically, the present application provides a method for preparing a thin film, comprising: providing a substrate, depositing a first layer of thin film on the substrate by chemical vapor deposition process, the first layer of thin film being thicker in the middle and thinner at the edges; measuring the thickness of the first layer of thin film at different positions by a metrology machine, to obtain a thickness distribution of the first layer of thin film; dividing the first layer of thin film into multiple regions according to the thickness distribution; calculating the deposition time required for depositing each region to a target thickness by atomic layer deposition process; and depositing a second layer of thin film on the first layer of thin film in different regions by atomic layer deposition process in sequence according to the calculated deposition time.

[0038] To make the objects, advantages and features of the present application clearer, the following further describes the present application in combination with the drawings and specific embodiments. It should be noted that the drawings are very simplified and not drawn to scale, and are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application. In addition, the structures shown in the drawings are often part of the actual structures. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0039] As used in the present application, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. As used in the present application, the term "or" is generally employed in its sense of "and / or" unless the content clearly dictates otherwise. As used in the present application, the term "several" is generally employed in its sense of "at least one" unless the content clearly dictates otherwise. As used in the present application, the term "at least two" is generally employed in its sense of "two or more" unless the content clearly dictates otherwise. In addition, the terms "first," "second," "third," are used only to describe a purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first," "second," "third" can explicitly or implicitly include one or at least two of the features, unless the content clearly indicates otherwise.

[0040] Figure 1 is a flowchart of a method for preparing a thin film according to an embodiment of the present application. As shown in Figure 1 , the method for preparing a thin film according to the embodiment of the present application comprises the following steps:

[0041] S1: providing a substrate, depositing a first layer of thin film on the substrate by using a chemical vapor deposition process, the first layer of thin film being thicker in the middle and thinner at the edges;

[0042] S2: measuring the thickness of the first layer of thin film at different positions by using a measuring machine, to obtain the thickness distribution of the first layer of thin film;

[0043] S3: dividing the first layer of thin film into multiple regions according to the thickness distribution;

[0044] S4: calculating the deposition time required for each region to deposit to a target thickness by using an atomic layer deposition process; and

[0045] S5: sequentially depositing a second layer of thin film on the first layer of thin film in different regions according to the calculated deposition time by using an atomic layer deposition process.

[0046] Figures 2 to 5 is a structural schematic diagram of each step of the method for preparing a thin film according to an embodiment of the present application. Next, the method for preparing a thin film according to an embodiment of the present application will be described in detail. Figure 1 , Figures 2 to 5

[0047] In step S1, please refer to Figure 2 , a substrate 10 is provided, a first layer of thin film 11 is deposited on the substrate 10 by using a chemical vapor deposition process, and the first layer of thin film 11 is thicker in the middle and thinner at the edges.

[0048] ​The material of the substrate 10 can be silicon, germanium, silicon germanium, silicon carbide, gallium arsenide or indium gallium, etc., can also be silicon on insulator, germanium on insulator; or can also be other materials, such as gallium arsenide and other III-V compounds. In the embodiment, the substrate 10 is a silicon substrate. The first layer of film 11 can be any film that needs to be formed on the substrate 10, for example, the material of the first layer of film 11 is silicon nitride. Before the first layer of film 11 is formed, other devices or film layers can also be formed on the substrate 10.

[0049] In the embodiment, the first layer of film 11 is formed by a chemical vapor deposition process. In the chemical vapor deposition process, the reaction gas diffuses freely in the furnace tube, the temperature and gas concentration of the central region of the substrate 10 are relatively low, which causes the thickness of the central region of the first layer of film 11 to be lower than the thickness of the edge region, forming a concave shape with a thin middle and thick edges.

[0050] In step S2, the thickness of the first layer of film 11 at different positions is measured by a metrology machine, and the thickness distribution of the first layer of film 11 is obtained.

[0051] In the embodiment, the thickness of the first layer of film 11 at different positions is measured by a THK metrology machine, that is, the thickness of a plurality of points on the first layer of film 11 is measured, for example, the thickness of 49 points is measured, and the 49 points are uniformly distributed on the first layer of film 11. Of course, the more points measured, the more accurate the thickness distribution of the first layer of film 11 obtained, but at the same time, the measurement time will be increased, and the number of points measured can be determined according to actual needs. The thickness of the first layer of film 11 gradually decreases from the edge region to the central region of the substrate 10.

[0052] In step S3, please refer to Figure 3 The first layer of film 11 is divided into a plurality of regions according to the thickness distribution.

[0053] In the embodiment, the first layer of film 11 is divided into three regions according to the thickness distribution. Figure 6 is a schematic diagram of the distribution of each region of the first layer of film provided by an embodiment of the present application, please refer to Figure 3 and Figure 6 The first layer of film 11 is divided into three regions: a central region A, a secondary central region B surrounding the central region A, and an edge region C surrounding the secondary central region B. The widths (dimensions in the diameter direction) of the three regions can be the same or different, which can be determined according to the thickness distribution, and regions with similar thicknesses are divided into the same region.

[0054] It can be understood that the first layer film 11 can also be divided into two regions, four regions or more regions, and the present application does not limit this. Starting from the center region, each region surrounds the previous region to form a plurality of annular regions with the same or different widths.

[0055] In step S4, the deposition time required for depositing the second layer film 12 in each region by the atomic layer deposition process is calculated.

[0056] For example, the average thickness of the first layer film 11 in each region is first calculated, i.e., the average value of the thicknesses in the same region is calculated according to the thicknesses of the first layer film 11 at different positions measured in step S2.

[0057] Then, the deposition time required for depositing the second layer film 12 in each region to the target thickness is calculated according to the deposition rate collected by the atomic layer deposition machine and the average thickness. The target thickness is the thickness of the film to be formed on the substrate 10. The deposition rate collected by the atomic layer deposition machine before depositing the film, the target thickness minus the average thickness in the same region, i.e., the thickness of the second layer film to be formed in the region, is divided by the deposition rate to obtain the deposition time required for depositing the film in the region by the atomic layer deposition process.

[0058] In another embodiment, the number of cycles required for depositing the second layer film 12 in each region by the atomic layer deposition process to the target thickness can also be calculated. The atomic layer deposition process only deposits a single layer of atoms or molecules each cycle, and the time for depositing a single layer of atoms or molecules is fixed. The number of cycles required is obtained by dividing the calculated deposition time by the time for a single cycle.

[0059] In step S5, please refer to Figure 4 and Figure 5 As shown, the second layer film 12 is deposited on the first layer film 11 in different regions by the atomic layer deposition process according to the calculated deposition time.

[0060] In step S4, the deposition time required for depositing the second layer film 12 in each region by the atomic layer deposition process is calculated, and in this step, the second layer film 12 is deposited in different regions according to the deposition time required for the region, so that the sum of the thicknesses of the first layer film 11 and the second layer film 12 in each region reaches the target thickness.

[0061] In an embodiment of the present application, the deposition of the second layer film 12 can be performed in each region in the order of the thickness of the first layer film 11 from small to large, i.e., the atomic layer deposition process is first performed on the region with the smallest thickness of the first layer film 11, and finally performed on the region with the largest thickness of the first layer film 11.

[0062] In another embodiment of the present application, the second layer film 12 is deposited on each region in order of the thickness of the first layer film 11 from large to small. The atomic layer deposition process is first performed on the region with the largest thickness of the first layer film 11, and finally performed on the region with the smallest thickness of the first layer film 11.

[0063] It can be understood that, since the substrate 10 is placed in the atomic layer deposition machine, the second layer film 12 can be formed in the remaining regions or adjacent regions when the atomic layer deposition process is performed on one region. Therefore, the deposition time of the subsequent region can be appropriately reduced.

[0064] In an embodiment of the present application, the thickness of the first layer film 11 in the region with the largest thickness of the first layer film 11 is equal to the target thickness, and the second layer film 12 is only deposited on the remaining regions. In another embodiment of the present application, the thickness of the first layer film 11 in the region with the largest thickness of the first layer film 11 is less than the target thickness, and the second layer film 12 is deposited on all regions.

[0065] The following two embodiments are described by taking the first layer film 11 as three regions.

[0066] In the first embodiment of the present application, the thickness of the first layer film 11 in the edge region C is equal to the target thickness, and the second layer film 12 is deposited on the center region A and the sub-center region B by the atomic layer deposition process, so that the sum of the thicknesses of the first layer film 11 and the second layer film 12 in each region of the substrate 10 is equal to the target thickness. For example, the second layer film 12 is first deposited on the first layer film 11 in the center region A by the atomic layer deposition process according to the calculated deposition time, and then the second layer film 12 is deposited on the first layer film 11 in the sub-center region B by the atomic layer deposition process according to the calculated deposition time. At this time, the sum of the thicknesses of the first layer film 11 and the second layer film 12 in the center region A, the sub-center region B and the edge region C all reaches the target thickness.

[0067] In the second embodiment of the present application, the thickness of the first layer film 11 in the edge area C is less than the target thickness, and the second layer film 12 is deposited on the first layer film 11 in the center area A, the sub-center area B and the edge area C by using the atomic layer deposition process, so that the sum of the thicknesses of the first layer film 11 and the second layer film 12 in each area on the substrate 10 is equal to the target thickness. For example, the second layer film 12 is first deposited on the first layer film 11 in the center area A by using the atomic layer deposition process according to the calculated deposition time, then the second layer film 12 is deposited on the first layer film 11 in the sub-center area B by using the atomic layer deposition process according to the calculated deposition time, and then the second layer film 12 is deposited on the first layer film 11 in the edge area C by using the atomic layer deposition process according to the calculated deposition time, at which time the sum of the thicknesses of the first layer film 11 and the second layer film 12 in the center area A, the sub-center area B and the edge area C reaches the target thickness.

[0068] In the first embodiment described above, the time of one atomic layer deposition process can be saved, and in the second embodiment, the surface of the substrate 10 is covered by the second layer film 12 formed by using the atomic layer deposition process, so that the film quality of the whole film can be improved.

[0069] Please refer to Figure 4 and Figure 5 As shown in the drawings, the thickness of the first layer film 11 is not uniform, the second layer film 12 with a certain thickness is formed in the center area A, the second layer film 12 with another thickness is formed in the sub-center area B, and finally the total thickness of the second layer film 12 and the first layer film 11 is also not uniform, but compared with the first layer film 11, the uniformity of the total thickness of the second layer film 12 and the first layer film 11 is greatly improved.

[0070] In the present embodiment, the first layer film 11 with an intermediate thickness and an edge thickness is first formed by using the chemical vapor deposition process, and then the second layer film 12 with different thicknesses is formed on the first layer film 11 in different areas by using the atomic layer deposition process, so that the thickness uniformity of the film can be improved. In addition, the second layer film 12 is formed by using only the atomic layer deposition process, which does not greatly increase the time cost, and is suitable for the deposition of a film with a relatively large thickness.

[0071] Figure 7 is a top view of an atomic layer deposition machine provided in an embodiment of the present application, Figure 8 is a schematic view of three gas inlet pipes provided in an embodiment of the present application. Please refer to Figure 7 and Figure 8As shown, the atomic layer deposition process is completed in an atomic layer deposition machine, which comprises a furnace tube 20, a plurality of gas inlet pipes 22 and a plurality of gas nozzles 23. The gas nozzles 23 are arranged on the gas inlet pipes 22 and protrude from the gas inlet pipes 22. The gas nozzles 23 on each gas inlet pipe 22 are arranged at the same angle with the vertical direction, and the gas nozzles 23 on different gas inlet pipes 22 are arranged at different angles with the vertical direction, so that the gas inlet pipes 22 can spray gas to different areas of the substrate 10. The furnace tube 20 is also provided with an exhaust port 24.

[0072] The number of gas inlet pipes 22 can be determined according to the number of areas in the first layer of film 11. For example, if the first layer of film 11 is divided into three areas, three gas inlet pipes 22 are needed in the atomic layer deposition machine. The gas inlet pipes 22 correspond to the areas one by one, and one gas inlet pipe 22 sprays gas to one area. Of course, the number of gas inlet pipes 22 arranged in the atomic layer deposition machine can be greater than the number of areas, and the gas inlet pipes 22 can be selected according to the number of areas. That is, the excess gas inlet pipes 22 can not be used.

[0073] The gas nozzles 23 protrude from the gas inlet pipes 22, and the gas nozzles 23 on each gas inlet pipe 22 are arranged at the same angle with the vertical direction, so that the gas nozzles 23 on each gas inlet pipe 22 can spray gas to the same area of the substrate 10. The gas nozzles 23 on different gas inlet pipes 22 are arranged at different angles with the vertical direction, so that the gas nozzles 23 on different gas inlet pipes 22 can spray gas to different areas of the substrate 10.

[0074] Please refer to Figure 8 As shown, the reaction chamber is provided with three gas inlet pipes 22, including a central area gas inlet pipe 22a for spraying gas to the central area A, a sub-central area gas inlet pipe 22b for spraying gas to the sub-central area B, and an edge area gas inlet pipe 22c for spraying gas to the edge area C. The angle α of the gas nozzles 23 of the central area gas inlet pipe 22a with the vertical direction is greater than the angle β of the gas nozzles 23 of the sub-central area gas inlet pipe 22b with the vertical direction, and the angle β of the gas nozzles 23 of the sub-central area gas inlet pipe 22b with the vertical direction is greater than the angle γ of the gas nozzles 23 of the edge area gas inlet pipe 22c with the vertical direction. That is, the farther the area is from the substrate, the smaller the angle of the gas nozzles 23 of the gas inlet pipe 22c corresponding to the area with the vertical direction.

[0075] For example, the steps of performing the atomic layer deposition process include: first, placing the substrate 10 on which the first layer of thin film 11 is formed into the furnace tube 20, pumping to the target vacuum degree, increasing the temperature to the target temperature, and waiting for the furnace tube 20 to reach stability; then, depositing the second layer of thin film 12 in the central region A; then, depositing the second layer of thin film 12 in the sub-central region B; and then, depositing the second layer of thin film 12 in the edge region C.

[0076] The method of depositing the second layer of thin film 12 in the central region by using the atomic layer deposition process includes: using the central region gas inlet pipe 22a to spray a precursor gas to the central region A of the substrate, and the precursor gas is adsorbed on the surface of the first layer of thin film 11; then, using the central region gas inlet pipe 22a to spray an inert gas to the central region A of the substrate to remove the excess precursor gas; then, using the central region gas inlet pipe 22a to spray a reaction gas to the central region A of the substrate, and the reaction gas reacts with the precursor gas to form an atomic layer; and then, repeating the above steps to perform the required deposition time to form the second layer of thin film 12 on the first layer of thin film 11 in the central region 22a.

[0077] Specifically, first, using the central region gas inlet pipe 22a to spray a precursor gas to the central region A of the substrate, and the precursor gas is adsorbed on the surface of the first layer of thin film 11. The time should be as short as possible to prevent the precursor gas from reaching other regions; then, using the central region gas inlet pipe 22a to spray an inert gas to the central region A of the substrate to blow away the excess precursor gas; then, using the central region gas inlet pipe 22a to spray a reaction gas to the central region A of the substrate, and the reaction gas reacts with the precursor gas to form the first atomic layer of the second layer of thin film 12. After that, the central region gas inlet pipe 22a can also be used to spray an inert gas to the central region A of the substrate to blow away the by-products and excess reaction gas. Then, repeating the above steps to complete the required deposition time or the required number of cycles to finally form the second layer of thin film 12 on the first layer of thin film 11 in the central region A.

[0078] The same is used to deposit the second layer of thin film 12 in the sub-central region B. Using the sub-central region gas inlet pipe 22b to spray a precursor gas to the sub-central region B of the substrate, and the precursor gas is adsorbed on the surface of the first layer of thin film 11; then, using the sub-central region gas inlet pipe 22b to spray an inert gas to the sub-central region B of the substrate to remove the excess precursor gas; then, using the sub-central region gas inlet pipe 22b to spray a reaction gas to the sub-central region B of the substrate, and the reaction gas reacts with the precursor gas to form an atomic layer; and then, repeating the above steps to perform the required deposition time to form the second layer of thin film 12 on the first layer of thin film 11 in the sub-central region B.

[0079] Specifically, first, the precursor gas is sprayed to the sub-center area B of the substrate by the sub-center area gas inlet pipe 22b, and the precursor gas is adsorbed on the surface of the first layer film 11. The time should be as short as possible to prevent the precursor gas from reaching other areas. Then, the inert gas is sprayed to the sub-center area B of the substrate by the sub-center area gas inlet pipe 22b to blow away the excess precursor gas. Then, the reaction gas is sprayed to the sub-center area B of the substrate by the sub-center area gas inlet pipe 22b to react with the precursor gas to form the first layer atomic layer of the second layer film 12. After that, the inert gas can also be sprayed to the sub-center area B of the substrate by the sub-center area gas inlet pipe 22b to blow away the by-products and excess reaction gas. Then, the above steps are repeated to complete the required deposition time or the required number of cycles, and finally the second layer film 12 is formed on the first layer film 11 in the sub-center area B.

[0080] The second layer film 12 is deposited in the edge area C by the same method. The precursor gas is sprayed to the edge area C of the substrate by the edge area gas inlet pipe 22c, and the precursor gas is adsorbed on the surface of the first layer film 11. Then, the inert gas is sprayed to the edge area C of the substrate by the edge area gas inlet pipe 22c to remove the excess precursor gas. Then, the reaction gas is sprayed to the edge area C of the substrate by the edge area gas inlet pipe 22c to react with the precursor gas to form an atomic layer. After that, the above steps are repeated to complete the required deposition time to form the second layer film 12 on the first layer film 11 in the edge area C.

[0081] Specifically, first, the precursor gas is sprayed to the edge area C of the substrate by the edge area gas inlet pipe 22c, and the precursor gas is adsorbed on the surface of the first layer film 11. The time should be as short as possible to prevent the precursor gas from reaching other areas. Then, the inert gas is sprayed to the edge area C of the substrate by the edge area gas inlet pipe 22c to blow away the excess precursor gas. Then, the reaction gas is sprayed to the edge area C of the substrate by the edge area gas inlet pipe 22c to react with the precursor gas to form the first layer atomic layer of the second layer film 12. After that, the inert gas can also be sprayed to the edge area C of the substrate by the edge area gas inlet pipe 22c to blow away the by-products and excess reaction gas. Then, the above steps are repeated to complete the required deposition time or the required number of cycles, and finally the second layer film 12 is formed on the first layer film 11 in the edge area C.

[0082] Finally, inert gas, such as nitrogen, can be introduced to anneal the deposited substrate in a nitrogen atmosphere to repair defects and repair the lattice resulting from the segmented deposition. This step can use any one or more of the center region gas inlet tube 22a, the sub-center region gas inlet tube 22b, and the edge region gas inlet tube 22c to inject the inert gas.

[0083] In summary, the method for preparing a thin film provided by the present application first provides a substrate, deposits a first layer of thin film on the substrate using a chemical vapor deposition process, the first layer of thin film is thin in the middle and thick at the edges; then measures the thickness of the first layer of thin film at different positions using a measurement machine, obtaining the thickness distribution of the first layer of thin film; then divides the first layer of thin film into multiple regions according to the thickness distribution; then calculates the deposition time required to deposit each region to a target thickness using an atomic layer deposition process; then deposits a second layer of thin film on the first layer of thin film in different regions using an atomic layer deposition process according to the calculated deposition time. The present application first forms a first layer of thin film that is thin in the middle and thick at the edges using a chemical vapor deposition process, and then forms a second layer of thin film with different thicknesses on the first layer of thin film in different regions using an atomic layer deposition process, thereby improving the thickness uniformity of the thin film. In addition, forming the second layer of thin film using only an atomic layer deposition process does not significantly increase the time cost, and is suitable for thin film deposition with larger film thickness.

[0084] The above description is only a description of the preferred embodiments of the present application, and is not any limitation on the scope of the present application. Any modification or change made by a person of ordinary skill in the art based on the above disclosure is within the scope of protection of the claims.

Claims

1. A method for preparing a thin film, characterized in that, Includes the following steps: A substrate is provided, and a first thin film is deposited on the substrate using a chemical vapor deposition process. The first thin film is thin in the middle and thick at the edges. The thickness of the first film layer at different locations was measured using a measuring machine to obtain the thickness distribution of the first film layer. The first thin film is divided into multiple regions according to its thickness distribution; Calculate the deposition time required for each region to reach the target thickness using atomic layer deposition (ALD) technology; as well as A second film is deposited sequentially on the first film in different regions using an atomic layer deposition process, according to the calculated deposition time.

2. The method for preparing the thin film according to claim 1, characterized in that, Methods for calculating the deposition time required to reach the target thickness for each region using atomic layer deposition include: Calculate the average thickness of the first layer of film in each region; The deposition time required to deposit to the target thickness for each region was calculated based on the deposition rate and average thickness collected by the atomic layer deposition machine.

3. The method for preparing the thin film according to claim 1, characterized in that, Based on the thickness distribution, the first thin film is divided into three regions: a central region, a sub-central region surrounding the central region, and an edge region surrounding the sub-central region.

4. The method for preparing the thin film according to claim 3, characterized in that, The thickness of the first thin film in the edge region is equal to the target thickness.

5. The method for preparing the thin film according to claim 4, characterized in that, The second thin film is deposited sequentially in the central region and the sub-central region using an atomic layer deposition process, such that the sum of the thicknesses of the first and second thin films in each region of the substrate is equal to the target thickness.

6. The method for preparing the thin film according to claim 3, characterized in that, The thickness of the first thin film in the edge region is less than the target thickness.

7. The method for preparing the thin film according to claim 6, characterized in that, The second thin film is deposited sequentially in the central region, the sub-central region and the edge region using an atomic layer deposition process, such that the sum of the thicknesses of the first thin film and the second thin film in each region of the substrate is equal to the target thickness.

8. The method for preparing the thin film according to claim 3, characterized in that, An atomic layer deposition process is performed in an atomic layer deposition machine, which includes a furnace tube. The furnace tube contains a support plate for multiple layers of substrates and multiple air inlet pipes. Each air inlet pipe is equipped with multiple nozzles for injecting gas into multiple substrates. The nozzles protrude from the air inlet pipes, and the nozzles in each air inlet pipe have the same angle with the vertical direction. The nozzles in different air inlet pipes have different angles with the vertical direction, so that different air inlet pipes inject gas into different areas of the substrate.

9. The method for preparing a thin film according to claim 8, characterized in that, The furnace tube is equipped with three air inlet pipes, including: a central region air inlet pipe that injects gas into the central region, a secondary central region air inlet pipe that injects gas into the secondary central region, and an edge region air inlet pipe that injects gas into the edge region; wherein the angle between the nozzle of the central region air inlet pipe and the vertical direction is greater than the angle between the nozzle of the secondary central region air inlet pipe and the vertical direction, and the angle between the nozzle of the secondary central region air inlet pipe and the vertical direction is greater than the angle between the nozzle of the edge region air inlet pipe and the vertical direction.

10. The method for preparing a thin film according to claim 9, characterized in that, A method for depositing a second thin film in the central region using atomic layer deposition includes: A precursor gas is injected into the central region of the substrate through the central region air inlet pipe, and the precursor gas is adsorbed onto the surface of the first thin film layer. Inert gas is injected into the central region of the substrate through the central region air inlet pipe to remove excess precursor gas; A reactive gas is injected into the central region of the substrate through the central region air inlet pipe, and the reactive gas reacts with the precursor gas to form an atomic layer; Repeat the above steps until the required deposition time is achieved to form a second film on the first film.

Images