A method for improving uniformity of an aluminum oxide passivation film

Abstract

This application provides a method for improving the uniformity of alumina passivation films, relating to the field of photovoltaic cell technology. The method includes: placing a substrate in a reaction chamber; heating the reaction chamber and introducing a first reaction source and an inert gas for deposition; subjecting the reaction chamber to a first vacuum, followed by a first purging with the inert gas, and then subjecting the reaction chamber to a second vacuum; introducing a second reaction source and the inert gas for atomic layer deposition; subjecting the reaction chamber to a third vacuum, followed by a second purging with the inert gas, and then subjecting the reaction chamber to a fourth vacuum; wherein the first reaction source comprises trimethylaluminum, the second reaction source comprises water vapor, and the inert gas comprises nitrogen. The method of this application can effectively make the passivation film growth more uniform, thereby improving the density and uniformity of the passivation film, and thus meeting the requirements of the photovoltaic cell field for alumina passivation films.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cell technology, and in particular to a method for improving the uniformity of alumina passivation films. Background Technology

[0002] In photovoltaic cells, alumina passivation film, formed by atomic layer deposition of TMA and water, is widely used for the protection and improvement of metal surfaces. The thickness of alumina passivation films typically ranges from a few nanometers to tens of nanometers. In photovoltaic cells, alumina passivation films not only form a dense oxide layer on the substrate surface, effectively isolating it from the external environment and preventing direct contact between the substrate and the external environment, thus preventing oxidation and corrosion, but also increase the surface hardness of the substrate material, further improving its wear resistance and corrosion resistance, significantly extending the lifespan of the photovoltaic cell. More importantly, alumina passivation films also possess excellent optical properties, increasing light absorption. In photovoltaic cells, a dense alumina passivation film enables more light energy to be converted into electrical energy; therefore, the uniformity of the alumina passivation film becomes crucial to the conversion efficiency of photovoltaic cells.

[0003] Alumina provides passivation for batteries through both field passivation and chemical passivation. The uniformity of alumina directly affects the final performance of the battery cell. With the continuous increase in workshop capacity, current atomic layer deposition (ALD) processes are all high-capacity large-chamber processes, which cannot guarantee that the silicon wafer at the end of the chamber is properly passivated. This results in poor uniformity of alumina at the end of the chamber and a large difference in alumina thickness from the chamber opening to the end. Therefore, how to further study and improve ALD technology to improve the quality and stability of the passivation film has become an urgent technical problem to be solved. Summary of the Invention

[0004] The purpose of this application is to provide a method for improving the uniformity of alumina passivation film to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] This application provides a method for improving the uniformity of an alumina passivation film, comprising:

[0007] The substrate is placed in the reaction chamber, which is then heated and a first reaction source and an inert gas are introduced to carry out deposition.

[0008] The reaction chamber is first evacuated, then the inert gas is introduced for a first purging, and then the reaction chamber is second evacuated.

[0009] ALD atomic layer deposition is performed by introducing a second reaction source and the inert gas.

[0010] The reaction chamber is evacuated for the third time, then the inert gas is introduced for the second purging, and then the reaction chamber is evacuated for the fourth time.

[0011] The first reaction source includes trimethylaluminum, the second reaction source includes water vapor, and the inert gas includes nitrogen.

[0012] Optionally, the final temperature of the heating is 230-245°C.

[0013] Optionally, the flow rate of the first reaction source is 4000-6000 ml / min, the flow rate of the inert gas is 4000-6000 ml / min, and the introduction time of the first reaction source and the inert gas is 5-6 s.

[0014] Optionally, the temperature of the first reaction source is 65-71°C.

[0015] Optionally, the flow rate of the second reaction source is 3000-4000 m³ / min, and the flow rate of the inert gas is 3000-4000 ml / min; the introduction time of the second reaction source and the inert gas is 8-9 s.

[0016] Optionally, the temperature of the second reaction source is 67-73°C.

[0017] Optionally, the first vacuuming time is 1-3 seconds; the second vacuuming time is 2-3 seconds; the third vacuuming time is 0.5-1.5 seconds; and the fourth vacuuming time is 2-3 seconds.

[0018] Optionally, during the first purging process, the flow rate of the inert gas is 15000-30000 ml / min, and the purging time is 6-7 seconds.

[0019] Optionally, during the second purging process, the flow rate of the inert gas is 15000-30000 ml / min, and the purging time is 2-3 seconds.

[0020] During the first and second purging processes described above, inert gases can be purged through multiple pipelines.

[0021] Optionally, the method is executed 34-36 times in total.

[0022] Compared with the prior art, the beneficial effects of this application include:

[0023] This application achieves the following through atomic deposition: Firstly, the introduction of an inert gas effectively accelerates gas flow within the chamber, thereby reducing the concentration difference between the front and rear sources and improving the inter-sheet uniformity of the alumina film. Secondly, the presence of the inert gas also enhances the quality of the passivation film. During atomic deposition, the inert gas removes excess reactants and byproducts from the reaction chamber, helping to maintain its cleanliness and preventing impurities from affecting the passivation film growth. Simultaneously, the inert gas slows down the reaction rate, resulting in more uniform passivation film growth and thus improving the density and uniformity of the passivation film.

[0024] The method described in this application can effectively meet the demand for alumina passivation films in the photovoltaic cell field, improve uniformity, and thus improve product quality. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0026] Figure 1 This is a schematic diagram of the production apparatus used in this application.

[0027] Key symbols: 1. Reaction chamber; 2. First high-purity nitrogen tank; 3. Second high-purity nitrogen tank; 4. Trimethylaluminum tank; 5. Water tank; 6. First nitrogen inlet valve; 7. Trimethylaluminum tank inlet valve; 8. Trimethylaluminum tank outlet valve; 9. Trimethylaluminum inlet valve; 10. Second nitrogen inlet valve; 11. Water tank inlet valve; 12. Water tank outlet valve; 13. Water inlet valve. Detailed Implementation

[0028] As used in this article:

[0029] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0030] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0031] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0032] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0033] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0034] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0035] This application provides a method for improving the uniformity of an alumina passivation film. To better illustrate the technical solution provided in this application, a general description of the technical solution is given before proceeding with the embodiments, as follows:

[0036] The method includes:

[0037] The substrate is placed in the reaction chamber, which is then heated and a first reaction source and an inert gas are introduced to carry out deposition.

[0038] The reaction chamber is first evacuated, then the inert gas is introduced for a first purging, and then the reaction chamber is second evacuated.

[0039] ALD atomic layer deposition is performed by introducing a second reaction source and the inert gas.

[0040] The reaction chamber is evacuated for the third time, then the inert gas is introduced for the second purging, and then the reaction chamber is evacuated for the fourth time.

[0041] The first reaction source includes trimethylaluminum, the second reaction source includes water vapor, and the inert gas includes nitrogen.

[0042] As can be seen, in the technical solution of this application, trimethylaluminum undergoes an adsorption reaction with the substrate within the reaction chamber, and trimethylaluminum is deposited on the substrate surface to form a deposited adsorption layer; water vapor reacts with the trimethylaluminum adsorbed on the substrate surface to generate alumina and methane. The alumina layer is deposited on the substrate surface, and the methane evaporates as a byproduct, thus not affecting the formation of the alumina passivation film.

[0043] Furthermore, after each reaction step in this application, the unreacted gases in the reaction chamber are evacuated and purged with an inert gas. This ensures that the reaction chamber is free of gas doping, avoiding unnecessary side reactions, and also contributes to the cleanliness of the reaction chamber, ensuring the quality of the next layer deposition. During atomic deposition, the material is in a high-temperature and highly reactive state, which facilitates ALD atomic layer deposition. On the one hand, introducing an inert gas can effectively accelerate the gas flow within the chamber, thereby reducing the concentration difference between the front and back sources and improving the inter-layer uniformity of the alumina film. On the other hand, the presence of the inert gas can also improve the quality of the passivation film. During atomic deposition, the inert gas can remove excess reactants and byproducts from the reaction chamber, such as excess trimethylaluminum vapor not adsorbed by the surface and reaction byproducts like methane. This helps maintain the cleanliness of the reaction chamber and avoids the influence of impurities on the growth of the passivation film. At the same time, the inert gas can also slow down the reaction rate, making the passivation film growth more uniform, thereby improving the density and uniformity of the passivation film.

[0044] In one optional embodiment, the final heating temperature is 230-245°C. On one hand, atomic layer deposition (ALD) is based on the principle of layer-by-layer growth through self-limiting adsorption interface chemical reactions, relying on the saturated adsorption of at least two compounds and irreversible gas-solid reactions. Heating the reaction chamber can increase the activity of the reactants, making them more readily react on the silicon wafer surface to generate an alumina passivation film. Furthermore, in this application, trimethylaluminum is used as the reaction source during ALD, which decomposes at this temperature and undergoes ALD ALD to generate alumina. Heating the reaction chamber ensures the precursor is fully decomposed and reacts completely with the reactants. On the other hand, heating the reaction chamber to this temperature helps form a dense, low-defect alumina passivation film. The alumina passivation film exhibits better chemical stability at high temperatures, resisting various chemical erosions and oxidation. This improves the uniformity and stability of the passivation film, thereby enhancing its passivation effect in photovoltaic cells.

[0045] Optionally, the final heating temperature can be 230°C, 235°C, 240°C, 245°C, or any value between 230°C and 245°C.

[0046] In an optional embodiment, the flow rate of the first reaction source is 4000-6000 ml / min, the flow rate of the inert gas is 4000-6000 ml / min, and the introduction time of the first reaction source and the inert gas is 5-6 s. During atomic layer deposition, the flow rate of trimethylaluminum directly affects the deposition rate and uniformity of the alumina passivation film. By controlling the flow rate and introduction time of trimethylaluminum, uniform deposition of the alumina passivation film on the substrate surface can be ensured, thereby avoiding defects such as uneven thickness.

[0047] Optionally, the flow rate of the first reactant can be 4000 ml / min, 4500 ml / min, 5000 ml / min, 5500 ml / min, 6000 ml / min, or any value between 4000 and 6000 ml / min. The flow rate of the inert gas can be 4000 ml / min, 4500 ml / min, 5000 ml / min, 5500 ml / min, 6000 ml / min, or any value between 4000 and 6000 ml / min. The introduction time of the first reaction source and the inert gas can be 5.1 s, 5.2 s, 5.3 s, 5.4 s, 5.5 s, 5.6 s, 5.7 s, 5.8 s, 5.9 s, 6 s, or any value between 5 and 6 s.

[0048] In one optional embodiment, the temperature of the first reaction source is 65-71°C. Higher temperatures accelerate the deposition rate and crystal growth rate, but excessively high temperatures can lead to the introduction of impurities and crystal instability. At this temperature, a balance can be struck between the deposition rate, crystal growth rate, and passivation film quality. Furthermore, the deposition temperature affects the diffusion rate of trimethylaluminum on the substrate surface. At lower temperatures, the diffusion rate of trimethylaluminum is slower, easily forming a dense structure and a smooth surface. At higher temperatures, the diffusion rate of molecules increases, potentially forming a porous structure and a rough surface. Therefore, by controlling the temperature of trimethylaluminum, the structure and morphology of the passivation film can be optimized.

[0049] Optionally, the temperature of the first reaction source can be 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, or any value between 65°C and 71°C.

[0050] In one optional embodiment, the flow rate of the second reaction source is 3000-4000 m³ / min, and the flow rate of the inert gas is 3000-4000 ml / min; the introduction time of the second reaction source and the inert gas is 8-9 s. By controlling the flow rate and time of the second reaction source, i.e., water vapor, the amount of water vapor can be precisely controlled, thereby optimizing the thickness and uniformity of the alumina passivation film. Furthermore, the water vapor at this source level can promote the orderly arrangement and close packing of alumina molecules, thereby optimizing the structure and morphology of the film.

[0051] Optionally, the flow rate of the second reaction source can be 3000 m³ / min, 3200 m³ / min, 3400 m³ / min, 3600 m³ / min, 3800 m³ / min, 4000 m³ / min, or any value between 3000 and 4000 m³ / min. The flow rate of the inert gas can be 3000 m³ / min, 3200 m³ / min, 3400 m³ / min, 3600 m³ / min, 3800 m³ / min, 4000 m³ / min, or any value between 3000 and 4000 m³ / min. The introduction time of the second reaction source and the inert gas can be 8 s, 8.1 s, 8.2 s, 8.3 s, 8.4 s, 8.5 s, 8.6 s, 8.7 s, 8.8 s, 8.9 s, 9 s, or any value between 8 and 9 s.

[0052] In one optional embodiment, the temperature of the second reaction source is 67-73°C. If the temperature of the water vapor is too low, its activity will decrease, the reaction rate will slow down, which may lead to a decrease in the passivation film deposition rate, or even failure to form a continuous passivation film; if the temperature is too high, the water vapor may overheat and decompose into hydrogen and oxygen, which will not only consume the reactants, but may also introduce impurities, affecting the quality and performance of the passivation film.

[0053] Optionally, the temperature of the second reaction source can be 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, or any value between 67°C and 73°C.

[0054] In one optional implementation, the first vacuuming time is 1-3 seconds; the second vacuuming time is 2-3 seconds; the third vacuuming time is 0.5-1.5 seconds; and the fourth vacuuming time is 2-3 seconds.

[0055] Optionally, the first vacuuming time can be 1s, 1.1s, 1.2s, 1.3s, 1.4s, 1.5s, 1.6s, 1.7s, 1.8s, 1.9s, 2s, 2.1s, 2.2s, 2.3s, 2.4s, 2.5s, 6s, 2.7s, 2.8s, 2.9s, or 3s, or any value between 1 and 3s. The second vacuuming time can be 2s, 2.1s, 2.2s, 2.3s, 2.4s, 2.5s, 2.6s, 2.7s, 2.8s, 2.9s, or 3s, or any value between 2 and 3s. The third vacuuming time can be 0.5s, 0.6s, 0.7s, 0.8s, 0.9s, 1s, 1.1s, 1.2s, 1.3s, 1.4s, or 1.5s, or any value between 0.5s and 1.5s. The fourth vacuuming time can be 2s, 2.1s, 2.2s, 2.3s, 2.4s, 2.5s, 2.6s, 2.7s, 2.8s, 2.9s, or 3s, or any value between 2 and 32s, 2.1s, 2.2s, 2.3s, 2.4s, 2.5s, 2.6s, 2.7s, 2.8s, 2.9s, or 3s.

[0056] In one optional embodiment, during the first purging process, the flow rate of the inert gas is 15000-30000 ml / min, and the purging time is 6-7 seconds.

[0057] Optionally, during the first purging process, the flow rate of the inert gas can be 15000 ml / min, 16000 ml / min, 17000 ml / min, 18000 ml / min, 19000 ml / min, 20000 ml / min, 21000 ml / min, 22000 ml / min, 23000 ml / min, 24000 ml / min, 25000 ml / min, 26000 ml / min, 27000 ml / min, 28000 ml / min, 29000 ml / min, or 30000 ml / min, or any value between 15000 and 30000 ml / min. The purging duration of the inert gas can be 6 s, 6.2 s, 6.4 s, 6.6 s, 6.8 s, or 7 s, or any value between 6 and 7 s.

[0058] In one optional embodiment, during the second purging process, the flow rate of the inert gas is 15000-3000 ml / min, and the purging time is 2-3 seconds.

[0059] Optionally, the flow rate of the inert gas during the second purging process can be optional. During the first purging process, the flow rate of the inert gas can be 15000 ml / min, 16000 ml / min, 17000 ml / min, 18000 ml / min, 19000 ml / min, 20000 ml / min, 21000 ml / min, 22000 ml / min, 23000 ml / min, 24000 ml / min, 25000 ml / min, 26000 ml / min, 27000 ml / min, 28000 ml / min, 29000 ml / min, 30000 ml / min, or any value between 15000 and 30000 ml / min. The purging duration of the inert gas can be 2 s, 2.2 s, 2.4 s, 2.6 s, 2.8 s, 3 s, or any value between 2 and 3 s.

[0060] In one optional implementation, the method is executed 34-36 times in total.

[0061] Optionally, the method can be executed 34, 35, or 36 times, or any value between 34 and 36.

[0062] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0063] like Figure 1 As shown, Figure 1 This is a schematic diagram of the production apparatus used in this application. In this apparatus, reaction chamber 1 is the reaction site for the ALD deposition reaction. The first high-purity nitrogen tank 2 and the second high-purity nitrogen tank 3 are connected to reaction chamber 1 via pipelines through a trimethylaluminum tank 4 and a water tank 5, respectively. In the trimethylaluminum pipeline: a first nitrogen inlet valve 6 and a trimethylaluminum tank inlet valve 7 are installed in the pipeline between the first high-purity nitrogen tank 2 and the trimethylaluminum tank 4 to control the introduction of nitrogen into the trimethylaluminum pipeline; a trimethylaluminum tank outlet valve 8 and a trimethylaluminum inlet valve 9 are installed between reaction chamber 1 and trimethylaluminum tank 4 to control the introduction of trimethylaluminum. In the water pipeline: a second nitrogen inlet valve 10 and a water tank inlet valve are installed between the second high-purity nitrogen tank 3 and the water tank 5 to control the introduction of nitrogen into the water pipeline; a water tank outlet valve 12 and a water inlet valve 13 are installed between the reaction chamber 1 and the water tank 5 to control the introduction of water vapor.

[0064] Example 1

[0065] This embodiment provides a method for improving the uniformity of alumina. Figure 1 The procedure is performed using the apparatus shown. The specific method is as follows:

[0066] Step 1: Place the substrate silicon wafer into reaction chamber 1 (equipment manufacturer: Wuxi Songyu Technology Co., Ltd.), heat reaction chamber 1 to 230-245℃, and simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum can inlet valve 7, the trimethylaluminum can outlet valve 8, and the trimethylaluminum inlet valve 9 to simultaneously introduce trimethylaluminum and nitrogen. The temperature of trimethylaluminum is 60℃, the flow rate of trimethylaluminum is 4000ml / min, the flow rate of nitrogen is 4000ml / min, and the introduction time is 5.5s.

[0067] Step 2: Wait 1 second, then evacuate the reaction chamber 1 and pipeline to a vacuum, removing the trimethylaluminum that did not participate in the reaction.

[0068] Step 3: Simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum canister inlet valve 7, the trimethylaluminum canister outlet valve 8, the trimethylaluminum inlet valve 9, the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13. Use nitrogen to purge the water line and the trimethylaluminum line for 6 seconds. The flow rate of nitrogen in the water line and the flow rate of nitrogen in the trimethylaluminum line are both 15,000 ml / min.

[0069] Step 4: Wait 2 seconds, then evacuate the reaction chamber 1 and its pipelines to a vacuum.

[0070] Step 5: Simultaneously open the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13 to introduce water vapor and nitrogen into the reaction chamber. The temperature of the water vapor is 45℃, the flow rate of the water vapor is 3000ml / min, the flow rate of the nitrogen is 3000ml / min, and the introduction time is 8s.

[0071] Step 6: Wait 0.5 seconds, then evacuate the reaction chamber and pipelines to create a vacuum, removing any unreacted water vapor.

[0072] Step 7: Simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum canister inlet valve 7, the trimethylaluminum canister outlet valve 8, the trimethylaluminum inlet valve 9, the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13. Use nitrogen to purge the water pipeline and the trimethylaluminum pipeline for 6 seconds. The flow rate of nitrogen in the water pipeline and the flow rate of nitrogen in the trimethylaluminum pipeline are both 15000 ml / min.

[0073] Step 8: Wait 2 seconds, then evacuate the reaction chamber and pipelines to a vacuum.

[0074] Repeat steps one through eight 35 times.

[0075] Example 2

[0076] This embodiment provides a method for improving the uniformity of alumina, the specific method is as follows:

[0077] Step 1: Place the substrate silicon wafer into reaction chamber 1, heat reaction chamber 1 to 230-245℃, and simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum can inlet valve 7, the trimethylaluminum can outlet valve 8, and the trimethylaluminum inlet valve 9 to simultaneously introduce trimethylaluminum and nitrogen. The temperature of trimethylaluminum is 60℃, the flow rate of trimethylaluminum is 5000ml / min, the flow rate of nitrogen is 5000ml / min, and the introduction time is 5.5s.

[0078] Step 2: Wait 1 second, then evacuate the reaction chamber 1 and pipeline to a vacuum, removing the trimethylaluminum that did not participate in the reaction.

[0079] Step 3: Simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum canister inlet valve 7, the trimethylaluminum canister outlet valve 8, the trimethylaluminum inlet valve 9, the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13. Use nitrogen to purge the water line and the trimethylaluminum line for 6 seconds. The flow rate of nitrogen in the water line and the flow rate of nitrogen in the trimethylaluminum line are both 15,000 ml / min.

[0080] Step 4: Wait 2 seconds, then evacuate the reaction chamber 1 and its pipelines to a vacuum.

[0081] Step 5: Simultaneously open the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13 to introduce water vapor and nitrogen into the reaction chamber. The temperature of the water vapor is 45℃, the flow rate of the water vapor is 3500ml / min, the flow rate of the nitrogen is 3500ml / min, and the introduction time is 8s.

[0082] Step 6: Wait 0.5 seconds, then evacuate the reaction chamber and pipelines to create a vacuum, removing any unreacted water vapor.

[0083] Step 7: Simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum canister inlet valve 7, the trimethylaluminum canister outlet valve 8, the trimethylaluminum inlet valve 9, the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13. Use nitrogen to purge the water pipeline and the trimethylaluminum pipeline for 6 seconds. The flow rate of nitrogen in the water pipeline and the flow rate of nitrogen in the trimethylaluminum pipeline are both 15000 ml / min.

[0084] Step 8: Wait 2 seconds, then evacuate the reaction chamber and pipelines to a vacuum.

[0085] Repeat steps one through eight 35 times.

[0086] Example 3

[0087] This embodiment provides a method for improving the uniformity of alumina, the specific method is as follows:

[0088] Step 1: Place the substrate silicon wafer into reaction chamber 1, heat reaction chamber 1 to 230-245℃, and simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum can inlet valve 7, the trimethylaluminum can outlet valve 8, and the trimethylaluminum inlet valve 9 to simultaneously introduce trimethylaluminum and nitrogen gas. The temperature of trimethylaluminum is 60℃, the flow rate of trimethylaluminum is 6000ml / min, the flow rate of nitrogen gas is 6000ml / min, and the introduction time is 5.5s.

[0089] Step 2: Wait 1 second, then evacuate the reaction chamber 1 and pipeline to a vacuum, removing the trimethylaluminum that did not participate in the reaction.

[0090] Step 3: Simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum canister inlet valve 7, the trimethylaluminum canister outlet valve 8, the trimethylaluminum inlet valve 9, the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13. Use nitrogen to purge the water line and the trimethylaluminum line for 6 seconds. The flow rate of nitrogen in the water line and the flow rate of nitrogen in the trimethylaluminum line are both 15,000 ml / min.

[0091] Step 4: Wait 2 seconds, then evacuate the reaction chamber 1 and its pipelines to a vacuum.

[0092] Step 5: Simultaneously open the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13 to introduce water vapor and nitrogen into the reaction chamber. The temperature of the water vapor is 45℃, the flow rate of the water vapor is 4000ml / min, the flow rate of the nitrogen is 4000ml / min, and the introduction time is 8s.

[0093] Step 6: Wait 0.5 seconds, then evacuate the reaction chamber and pipelines to create a vacuum, removing any unreacted water vapor.

[0094] Step 7: Simultaneously open the first nitrogen inlet valve 6, the trimethylaluminum canister inlet valve 7, the trimethylaluminum canister outlet valve 8, the trimethylaluminum inlet valve 9, the second nitrogen inlet valve 10, the water tank inlet valve 11, the water tank outlet valve 12, and the water inlet valve 13. Use nitrogen to purge the water pipeline and the trimethylaluminum pipeline for 6 seconds. The flow rate of nitrogen in the water pipeline and the flow rate of nitrogen in the trimethylaluminum pipeline are both 15000 ml / min.

[0095] Step 8: Wait 2 seconds, then evacuate the reaction chamber and pipelines to a vacuum.

[0096] Repeat steps one through eight 35 times.

[0097] Comparative Example 1

[0098] This comparative example provides a method for preparing an alumina passivation film, the specific method of which is as follows:

[0099] Step 1: Place the substrate silicon wafer into the reaction chamber, heat the reaction chamber to 230-245℃, and introduce trimethylaluminum, wherein the temperature of trimethylaluminum is 60℃, the flow rate of trimethylaluminum is 6000ml / min, and the introduction time is 5.5s.

[0100] Step 2: Wait 1 second, then evacuate the reaction chamber and pipeline to a vacuum, removing any unreacted trimethylaluminum.

[0101] Step 3: Purge the water line and the trimethylaluminum line with nitrogen for 6 seconds. The flow rate of nitrogen in the water line and the flow rate of nitrogen in the trimethylaluminum line are both 15,000 ml / min.

[0102] Step 4: Wait 2 seconds and evacuate the reaction chamber and pipelines to a vacuum.

[0103] Step 5: Introduce water vapor and nitrogen into the reaction chamber. The water vapor temperature is 45℃, the water vapor flow rate is 4000ml / min, and the introduce time is 8s.

[0104] Step 6: Wait 0.5 seconds, then evacuate the reaction chamber and pipelines to create a vacuum, removing any unreacted water vapor.

[0105] Step 7: Purge the water line and the trimethylaluminum line with nitrogen for 6 seconds. The flow rate of nitrogen in the water line and the flow rate of nitrogen in the trimethylaluminum line should both be 15,000 ml / min.

[0106] Step 8: Wait 2 seconds, then evacuate the reaction chamber and pipelines to a vacuum.

[0107] Repeat steps one through eight 35 times.

[0108] Experimental Example

[0109] The thickness of the alumina on the silicon substrates prepared using the methods of Examples 1-3 and Comparative Example 1 was measured, and the results are shown in Table 1.

[0110] Table 1. Thickness of alumina passivation film in the examples and comparative examples.

[0111]

[0112]

[0113] As can be seen, this application adds nitrogen to the source flow step based on the original process. By adjusting the amount of nitrogen, the flow and distribution of the source are promoted, thereby optimizing the uniformity of alumina.

[0114] After the improvement, the uniformity of a single piece is controlled within 11%, and the uniformity of a single tube is reduced by 7% compared with that before the improvement.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0116] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for improving the uniformity of an alumina passivation film, characterized in that, include: The substrate is placed in the reaction chamber, which is then heated and a first reaction source and an inert gas are introduced to carry out deposition. The reaction chamber is first evacuated, then the inert gas is introduced for a first purging, and then the reaction chamber is second evacuated. A second reaction source and the inert gas are introduced to perform atomic layer deposition; The reaction chamber is evacuated for the third time, then the inert gas is introduced for the second purging, and then the reaction chamber is evacuated for the fourth time. The first reaction source includes trimethylaluminum, the second reaction source includes water vapor, and the inert gas includes nitrogen.

2. The method for improving the uniformity of the alumina passivation film according to claim 1, characterized in that, The final temperature of the heating is 230-245℃.

3. The method for improving the uniformity of the alumina passivation film according to claim 1, characterized in that, The flow rate of the first reaction source is 4000-6000 ml / min, the flow rate of the inert gas is 4000-6000 ml / min, and the introduction time of the first reaction source and the inert gas is 5-6 s.

4. The method for improving the uniformity of the alumina passivation film according to claim 3, characterized in that, The temperature of the first reaction source is 65-71℃.

5. The method for improving the uniformity of the alumina passivation film according to claim 1, characterized in that, The flow rate of the second reaction source is 3000-4000 m³ / min, and the flow rate of the inert gas is 3000-4000 ml / min; the introduction time of the second reaction source and the inert gas is 8-9 s.

6. The method for improving the uniformity of the alumina passivation film according to claim 5, characterized in that, The temperature of the second reaction source is 67-73℃.

7. The method for improving the uniformity of the alumina passivation film according to claim 1, characterized in that, At least one of the following conditions must be met: a. The first vacuuming time is 1-3 seconds; b. The second vacuuming time is 2-3 seconds; c. The third vacuuming time is 0.5-1.5 seconds; d. The fourth vacuuming time is 2-3 seconds.

8. The method for improving the uniformity of the alumina passivation film according to claim 1, characterized in that, During the first purging process, the flow rate of the inert gas is 15000-30000 ml / min, and the purging time is 6-7 seconds.

9. The method for improving the uniformity of the alumina passivation film according to claim 1, characterized in that, During the second purging process, the flow rate of the inert gas is 15000-30000 ml / min, and the purging time is 2-3 seconds.

10. The method for improving the uniformity of the alumina passivation film according to any one of claims 1-9, characterized in that, The method is executed 34-36 times in total.

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