Preparation method and device of silicon dioxide film, catalyst

Abstract

This invention provides a method and apparatus for preparing a silica thin film, including a catalyst. The preparation method includes: providing a first gas and a second gas, wherein the first gas comprises nitrous oxide and the second gas comprises a siloxane; using the catalyst to catalyze at least partially decompose the nitrous oxide in the first gas to obtain a third gas; mixing the third gas with the second gas and performing a vapor-phase chemical deposition reaction to generate a silica thin film. This method can effectively reduce the activation decomposition temperature of nitrous oxide, thereby reducing energy consumption and byproducts, and avoiding the adverse effects caused by insufficient thermal budget.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to a method and apparatus for preparing silicon dioxide thin films, and a catalyst. Background Technology

[0002] Nitrous oxide (N₂O) is widely used in the fabrication of semiconductor devices, such as in chemical vapor deposition (CVD) reactions with gaseous siloxanes to form silicon dioxide dielectric layers. While N₂O is chemically stable, directly using room-temperature N₂O with gaseous siloxanes for CVD to produce silicon dioxide dielectric layers results in slow reaction rates and poor film uniformity. Therefore, current technologies typically conduct the CVD reaction of N₂O with gaseous siloxanes at temperatures above 800°C. This allows N₂O to first activate and decompose at high temperatures, forming reactive oxygen species, which then react with the gaseous siloxanes for CVD, resulting in faster deposition rates and better film uniformity. However, high-temperature reaction conditions lead to high energy consumption, numerous byproducts, and may also affect the performance of the fabricated semiconductor devices due to thermal budget limitations. Summary of the Invention

[0003] The purpose of this invention is to provide a method and apparatus for preparing silica thin films, as well as a catalyst, in order to solve the above-mentioned technical problems.

[0004] To solve the above-mentioned technical problems, the present invention provides a method for preparing a silicon dioxide thin film, comprising:

[0005] A first gas and a second gas are provided, wherein the first gas comprises nitrous oxide and the second gas comprises siloxane;

[0006] The first gas is at least partially decomposed using a catalyst to obtain a third gas;

[0007] The third gas is mixed with the second gas and subjected to a chemical vapor deposition reaction to generate a silicon dioxide thin film.

[0008] Optionally, the catalyst has a nanosheet structure and includes exposed... <112> Cobalt tetroxide on the crystal face and silver oxide dispersed on the surface of cobalt tetroxide.

[0009] Optionally, the catalyst is prepared by the following steps:

[0010] Cobalt nitrate solution, silver nitrate solution, and surfactant are dissolved in a solvent to obtain a mixture;

[0011] The mixture is stirred until it forms a uniform, transparent red sol.

[0012] The sol is heated to cause at least partial evaporation of the solvent and to form a black gel.

[0013] The gel was calcined to obtain the catalyst.

[0014] Optionally, the molar ratio of silver ions in the silver nitrate solution to cobalt ions in the cobalt nitrate solution is 0.01 to 0.03, and the surfactant is a nonionic surfactant; the temperature of the heat treatment is 60°C to 80°C; and the temperature of the calcination treatment is 300°C to 400°C for 2 to 5 hours.

[0015] Optionally, the surfactant includes at least one of poloxamer 407, P123, Triton X-100, and polyvinylpyrrolidone.

[0016] Optionally, the preparation method further includes performing the following steps after obtaining the third gas and before mixing the third gas with the second gas:

[0017] The third gas is filtered using a filter element.

[0018] Optionally, the filter element includes a porous matrix and an electron trapping material dispersed on the porous matrix.

[0019] To address the aforementioned technical problems, the present invention also provides an apparatus for preparing a silica thin film, used to perform the silica thin film preparation method as described above. The apparatus includes a pretreatment chamber and a chemical vapor deposition chamber. The pretreatment chamber has an inlet end and an outlet end, the outlet end being connected to the chemical vapor deposition chamber. The pretreatment chamber includes a decomposition zone, which is filled with the catalyst.

[0020] Optionally, the pretreatment chamber further includes a filtration zone located on the side of the decomposition zone near the outlet end, and the filtration zone is filled with filter elements.

[0021] To achieve the above objectives, the present invention also provides a catalyst, said catalyst having a nanosheet structure and comprising an exposed... <112> Cobalt tetroxide on the crystal face and silver oxide dispersed on the surface of cobalt tetroxide.

[0022] Compared with the prior art, the method and apparatus for preparing silica thin films and the catalyst of the present invention have the following advantages:

[0023] The aforementioned method for preparing a silica thin film includes: providing a first gas and a second gas, wherein the first gas comprises nitrous oxide and the second gas comprises a siloxane; using a catalyst to catalyze at least partially decompose the nitrous oxide in the first gas to obtain a third gas; mixing the third gas with the second gas and performing a vapor-phase chemical deposition reaction to generate a silica thin film. This method can effectively reduce the activation decomposition temperature of nitrous oxide, thereby reducing energy consumption and byproducts, and avoiding the adverse effects caused by insufficient thermal budget. Attached Figure Description

[0024] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein:

[0025] Figure 1 This is a flowchart of a method for preparing a silicon dioxide thin film according to some embodiments of the present invention;

[0026] Figure 2 This is a transmission electron microscope (TEM) image of the catalyst used in the method for preparing a silica thin film according to an embodiment of the present invention.

[0027] Figure 3 This is a comparison graph of the activation rate of nitrous oxide in the method for preparing silicon dioxide thin film according to one embodiment of the present invention and the activation rate of nitrous oxide in a comparative example.

[0028] Figure 4 This is a schematic diagram of the apparatus for preparing silicon dioxide thin films according to some embodiments of the present invention.

[0029] [The reference numerals in the attached figures are explained as follows]: 10-Pretreatment chamber, 11-First inlet end, 12-Outlet end, 20-Chemical vapor deposition chamber, 21-Second inlet end, 22-Third inlet end, 30-Catalyst, 40-Filter element. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components related to the present invention and are not drawn according to the actual number, shape, and size of components in the actual implementation. In the actual implementation, the type, quantity, and proportion of each component can be arbitrarily changed, and the component layout may also be more complex.

[0031] Furthermore, while each embodiment described below possesses one or more technical features, this does not imply that users of the present invention must simultaneously implement all technical features in any embodiment, or can only separately implement some or all technical features in different embodiments. In other words, provided it is feasible, those skilled in the art can, based on the disclosure of the present invention and depending on design specifications or implementation requirements, selectively implement some or all technical features in any embodiment, or selectively implement a combination of some or all technical features in multiple embodiments, thereby increasing the flexibility in implementing the present invention.

[0032] As used herein, the singular forms “a,” “an,” and “the” include plural objects, and the plural form “multiple” includes two or more objects, unless otherwise expressly indicated. As used herein, the term “or” is generally used to include the meaning of “and / or,” unless otherwise expressly indicated, and the terms “installed,” “connected,” and “linked” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Connections can be mechanical or electrical. Connections can be direct or indirect through an intermediate medium, and can be internal communication between two elements or an interaction between two elements. Relational terms such as “first,” “second,” etc., are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor do they indicate or imply relative importance or implicitly specify the number of indicated technical features. It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0033] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the objectives of the embodiments of the present invention. The same or similar reference numerals in the drawings represent the same or similar parts.

[0034] One objective of this invention is to provide a method for preparing a silicon dioxide thin film, the process of which is as follows: Figure 1 As shown, it includes:

[0035] Step S1: Provide a first gas including nitrous oxide and a second gas including siloxane.

[0036] Step S3, using catalyst 30 (e.g. Figure 4 (As shown) Catalyzes at least partially the decomposition of nitrous oxide in the first gas to obtain a third gas.

[0037] Step S5: Mix the third gas with the second gas and perform a chemical vapor deposition reaction to generate a silicon dioxide thin film.

[0038] The reaction that occurs in step S3 is: N2O = N2 + [O], where [O] represents active oxygen, which has strong oxidizing properties.

[0039] The reaction that occurs in step S5 is: SiH2Cl2 + 2[O] = SiO2 + 2HCl.

[0040] That is, in this embodiment of the invention, the catalyst 30 is first used to catalyze the decomposition of nitrous oxide to obtain active oxygen with strong oxidizing properties. Then, the third gas including the active oxygen undergoes a chemical vapor deposition reaction with the second gas to generate a silicon dioxide thin film. This approach lowers the decomposition temperature of nitrous oxide to 300°C–400°C, thereby reducing the subsequent chemical vapor deposition reaction temperature to 300°C–400°C. This significantly reduces energy consumption when preparing silicon dioxide thin films using chemical vapor deposition and minimizes side reactions caused by high temperatures. Furthermore, by pre-decomposing nitrous oxide to obtain active oxygen before performing the chemical vapor deposition reaction, the reaction rate can be increased, leading to rapid formation of the silicon dioxide thin film and improved uniformity of the generated film.

[0041] The following section will further explain each step of the preparation method.

[0042] In step S1, the first gas may further include a first carrier gas, which includes, but is not limited to, nitrogen. The volume percentage of nitrous oxide in the first gas is determined as needed, for example, 0.1% to 10%.

[0043] The second gas may include a second carrier gas, which may also be nitrogen. The volume percentage of siloxane in the second gas is determined as needed.

[0044] The specific type of catalyst 30 described in this embodiment of the invention is not particularly limited, as long as it can catalyze the decomposition of nitrous oxide.

[0045] In a preferred embodiment, the catalyst 30 has a nanosheet structure and includes exposed... <112> The catalyst consists of cobalt tetroxide crystals and silver oxide dispersed on the surface of cobalt tetroxide. In this catalyst, the presence of silver oxide weakens the bond energy of the Co-O bonds in cobalt tetroxide, promotes the formation of oxygen vacancies, and thus accelerates the desorption of active oxygen generated by the decomposition of nitrous oxide, thereby giving the catalyst 30 high catalytic activity.

[0046] In a preferred embodiment, the catalyst 30 is prepared by the following steps:

[0047] Step S01: Dissolve cobalt nitrate solution, silver nitrate solution, and surfactant in a solvent to obtain a mixture.

[0048] Step S02: Stir the mixture until it forms a uniform, transparent red sol.

[0049] Step S03: Heat the sol to cause at least a partial evaporation of the solvent and to form a black gel.

[0050] Step S04: Calcine the gel to obtain the catalyst 30.

[0051] In step S01, the molar ratio of silver ions to cobalt ions is 0.01–0.03. The surfactant is a nonionic surfactant, specifically at least one of poloxamer 407, P123, Triton X-100, and polyvinylpyrrolidone. The solvent includes at least one of ethanol, methanol, acetic acid, diethyl ether, and water.

[0052] In step S02, there are no particular limitations on the speed and time of the stirring process, as long as a uniform, transparent red sol is obtained in the end.

[0053] In step S03, the heating temperature can be between 60°C and 80°C, and the specific heating time can be determined as needed, as long as a black gel is ultimately obtained. Alternatively, step S03 can be performed in an oven.

[0054] In step S04, the calcination temperature can be 300℃~400℃, and the duration can be 2h~5h.

[0055] Furthermore, in step S3, the reaction temperature is selected within the range of 300℃ to 400℃, specifically determined based on the catalytic activity of catalyst 30 and the volume percentage of nitrous oxide in the first gas. The reaction pressure is selected within the range of atmospheric pressure to 1 MPa. Generally, high pressure can suppress the formation of byproducts from the decomposition of nitrous oxide, but the pressure resistance of the reactor used to perform step S3 must also be considered when actually selecting the reaction pressure. The volume hourly space velocity is 5000 h⁻¹. -1 ~20000h -1 The selection of the catalyst is determined based on its catalytic activity. Generally, the higher the catalytic activity of the catalyst 30, the greater the volume hourly space velocity should be.

[0056] In step S5, the reaction temperature can be between 300℃ and 400℃, and other conditions can be referred to the prior art.

[0057] Further preferably, continue to refer to Figure 1 The preparation method further includes a step S4 performed after step S3 and before step S5, wherein step S4 includes: using a filter element 40 (such as...) Figure 4 The third gas is filtered (as shown). This is done because when nitrous oxide is decomposed using catalyst 30, the resulting third gas may carry components of catalyst 30. If it is not treated, it may cause contamination of the silica film obtained in step S5.

[0058] When the catalyst 30 includes a metal element, such as the aforementioned exposure <112> When cobalt tetroxide is crystallized and silver oxide is dispersed on the surface of cobalt tetroxide, metal elements may be present in the third gas. Preferably, the filter element 40 comprises a porous substrate and an electron trapping material dispersed on the porous substrate. This provides the filter element 40 with stable metal trapping sites formed by lattice defects, which can trap metal elements in the third gas, reducing or even eliminating contamination of the subsequently deposited silicon dioxide film by metal elements.

[0059] In a specific example, the porous substrate comprises porous alumina ceramic, and the electron trapping material comprises rare earth-doped zirconium oxide, such as yttrium-doped zirconium oxide (Y₂O₃-ZrO₂). The preparation method of the rare earth-doped zirconium oxide material can refer to existing technologies, and the specific method of dispersing rare earth-doped zirconium oxide on the porous alumina ceramic can also refer to existing technologies, and will not be elaborated here.

[0060] The advantages of the preparation method will be explained next through a specific embodiment and a comparative example.

[0061] <Example 1>

[0062] In this embodiment, the catalyst is prepared through the aforementioned steps S01 to S04, wherein the molar ratio of silver ions to cobalt ions in step S01 is 0.02, the surfactant is poloxamer 407, the solvent is ethanol, the heating temperature in step S03 is about 65°C, and the calcination temperature in step S04 is 300°C for 3 hours.

[0063] Figure 2 A transmission electron microscope (TEM) schematic diagram of the catalyst 30 as described in this embodiment is shown. Figure 2 As can be seen, cobalt tetroxide <112> Crystal planes exposed, and <112> The distance between the crystal planes is 0.28 nm.

[0064] The catalyst 30 is used to perform the aforementioned steps S1, S3, S4 and S5, and the change in the activation rate of nitrous oxide in step S3 over time is detected, and the composition of the silica film generated in step S5 is detected.

[0065] The change in the activation rate of nitrous oxide over time in step S3 is as follows: Figure 3 As shown in curve 1, approximately 5 minutes after the start of step S3, the activation rate of nitrous oxide reaches 50%. Within 20 minutes after the start of step S3, the activation rate of nitrous oxide continues to rise. From 20 minutes to 3000 minutes after the start of step S3, the activation rate of nitrous oxide remains above 95%.

[0066] Testing revealed that the silicon dioxide film generated in this embodiment does not contain any metal elements.

[0067] Comparative Example 1

[0068] In this comparative example, nitrous oxide and siloxane were directly subjected to chemical vapor deposition at 800℃~900℃, and the activation rate of nitrous oxide was detected over time. The results are as follows: Figure 3 As shown in curve 2.

[0069] As can be seen from curve 2, in this comparative example, the activation rate of nitrous oxide maintained an upward trend within 20 minutes after the start of the chemical vapor deposition reaction, but it was always below 20%. After 20 minutes after the start of the chemical vapor deposition reaction, the rate of increase of the activation rate of nitrous oxide increased, but the activation efficiency of nitrous oxide only reached 60% at 3000 minutes after the start of the reaction.

[0070] Comparing Example 1 and Comparative Example 1, it can be seen that, compared with the prior art, the preparation method provided by the embodiments of the present invention significantly reduces the reaction temperature and significantly increases the activation rate of nitrous oxide. The increased activation rate of nitrous oxide inevitably leads to a faster formation rate of the silicon dioxide thin film.

[0071] The second objective of this embodiment is to provide a method such as... Figure 4 The apparatus shown is for preparing a silicon dioxide thin film, which is used to perform the silicon dioxide thin film preparation method as described above. (Reference) Figure 4 The preparation apparatus includes a pretreatment chamber 10 and a chemical vapor deposition chamber 20. The pretreatment chamber 10 has a first inlet end 11 and an outlet end 12. The outlet end 12 is connected to the chemical vapor deposition chamber 20. The pretreatment chamber 10 includes a decomposition zone (not shown in the figure), which is filled with the catalyst 30.

[0072] In practice, the chemical vapor deposition chamber 20 has a second inlet end 21 and a third inlet end 22, and the second inlet end 21 is connected to the outlet end 12 through a pipe.

[0073] When preparing a silica thin film using the aforementioned apparatus, the first gas flows into the pretreatment chamber 10 from the first inlet end 11 and contacts the catalyst 30 in the decomposition zone. Here, nitrous oxide in the first gas is at least partially decomposed under the catalysis of the catalyst 30, causing the first gas to form the third gas. The third gas flows into the chemical vapor deposition chamber 20 from the outlet end 12 and the second inlet end 21. The second gas flows into the chemical vapor deposition chamber 20 from the third inlet end 22. The second gas and the third gas mix in the chemical vapor deposition chamber and undergo a chemical vapor deposition reaction to generate a silica thin film.

[0074] Preferably, the pretreatment chamber 10 further includes a filtration zone (not shown in the figure), which is located on the side of the decomposition zone near the outlet end 12, and the filtration zone is filled with the filter element 40.

[0075] Preferably, the first inlet end 11, the decomposition zone, the filtration zone, and the outlet end 12 are arranged in an upward direction. Thus, the first inlet end 11, the catalyst 30, the filter element 40, and the outlet end 12 are arranged in an upward direction. The first gas flows into the pretreatment chamber 10 from the first inlet end 11, then flows upward through the catalyst 30 to form the third gas. The third gas then flows upward through the filter element 40 and exits from the outlet end 12. This arrangement increases the contact time between the first gas and the catalyst 30, thereby improving the catalytic effect, and also increases the contact time between the third gas and the filter element 40, thereby improving the filtration effect.

[0076] In addition, the preparation apparatus also includes a heater (not shown in the figure) for heating the pretreatment chamber 10 and the chemical vapor deposition chamber 20.

[0077] The third objective of this invention is to provide a catalyst, which is the aforementioned catalyst 30, and its preparation method includes the aforementioned steps S01, S02, S03 and S04.

[0078] Step S3 was performed using the catalyst 30, and the lifetime of the catalyst 30 was tested. The test revealed that the lifetime of the catalyst could reach more than 2000 hours.

[0079] While the present invention has been disclosed above, it is not limited thereto. Those skilled in the art can make various modifications and variations to the present invention without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, the present invention also intends to include such modifications and variations.

Claims

1. A method for preparing a silicon dioxide thin film, characterized in that, include: A first gas and a second gas are provided, wherein the first gas comprises nitrous oxide and the second gas comprises siloxane; The first gas is at least partially decomposed using a catalyst to obtain a third gas; The third gas is mixed with the second gas and subjected to a chemical vapor deposition reaction to generate a silicon dioxide thin film.

2. The method for preparing a silicon dioxide thin film according to claim 1, characterized in that, The catalyst has a nanosheet structure and includes exposed... <112> Cobalt tetroxide on the crystal face and silver oxide dispersed on the surface of cobalt tetroxide.

3. The method for preparing a silicon dioxide thin film according to claim 2, characterized in that, The catalyst is prepared by the following steps: Cobalt nitrate solution, silver nitrate solution, and surfactant are dissolved in a solvent to obtain a mixture; The mixture is stirred until it forms a uniform, transparent red sol. The sol is heated to cause at least partial evaporation of the solvent and to form a black gel. The gel was calcined to obtain the catalyst.

4. The catalyst according to claim 3, characterized in that, The molar ratio of silver ions in the silver nitrate solution to cobalt ions in the cobalt nitrate solution is 0.01 to 0.03, and the surfactant is a nonionic surfactant; the heating treatment temperature is 60℃ to 80℃; the calcination treatment temperature is 300℃ to 400℃, and the time is 2h to 5h.

5. The catalyst according to claim 4, characterized in that, The surfactant includes at least one of poloxamer 407, P123, Triton X-100, and polyvinylpyrrolidone.

6. The method for preparing a silicon dioxide thin film according to claim 1, characterized in that, The preparation method further includes actions performed after obtaining the third gas and before mixing the third gas with the second gas: The third gas is filtered using a filter element.

7. The method for preparing a silicon dioxide thin film according to claim 6, characterized in that, The filter element includes a porous matrix and an electron trapping material dispersed on the porous matrix.

8. An apparatus for preparing a silicon dioxide thin film, used to perform the method for preparing a silicon dioxide thin film as described in any one of claims 1-7, characterized in that, The preparation apparatus includes a pretreatment chamber and a chemical vapor deposition chamber; the pretreatment chamber has an inlet end and an outlet end, the outlet end being connected to the chemical vapor deposition chamber; the pretreatment chamber includes a decomposition zone, the decomposition zone being filled with the catalyst.

9. The apparatus for preparing a silicon dioxide thin film according to claim 8, characterized in that, The pretreatment chamber further includes a filtration zone located on the side of the decomposition zone near the outlet end, and the filtration zone is filled with filter elements.

10. A catalyst, characterized in that, The catalyst has a nanosheet structure and includes exposed... <112> Cobalt tetroxide on the crystal face and silver oxide dispersed on the surface of cobalt tetroxide.

Images