rare earth metal oxide film on the surface of a substrate

Abstract

A method for producing a rare earth metal oxide film on the surface of a substrate is disclosed. The method includes, in any order and alternately, step a) exposing the deposition surface to an oxygen alcohol precursor in a reaction space to adsorb at least a portion of the oxygen alcohol precursor onto the deposition surface of the substrate, and then purging the deposition surface with an inert gas for a first period of 1 to 180 seconds; and step b) exposing the deposition surface to a rare earth metal precursor to adsorb at least a portion of the rare earth metal precursor onto the deposition surface of the substrate, and then purging the deposition surface with an inert gas for a second period. The use of the method is also disclosed.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a rare earth metal oxide film on the surface of a substrate. The present disclosure further relates to the use of the method.

Background Art

[0002] Yttrium oxide, like other rare earth metal oxides, is known to be a moisture-absorbing material. The adsorption of moisture to the oxide is strong, and desorption is often slow. In processes such as atomic layer deposition (ALD), this leads to deterioration of the process conditions and non-uniformity of the rare earth metal oxide film produced. Further, there is a need for a method capable of manufacturing a rare earth metal oxide film having properties suitable for further applications.

Summary of the Invention

[0003] A method for manufacturing a rare earth metal oxide film on the surface of a substrate is provided. The method includes, in a reaction space, exposing a deposition surface to an alcohol-based precursor of oxygen to adsorb at least a part of the alcohol-based precursor of oxygen onto the deposition surface of the substrate, and then purging the deposition surface with an inert gas for a first period of 1 to 180 seconds in step a); exposing the deposition surface to a precursor of a rare earth metal to adsorb at least a part of the precursor of the rare earth metal onto the deposition surface of the substrate, and then purging the deposition surface with an inert gas for a second period in step b), and including performing these steps alternately in any order.

[0004] Also, it is disclosed that the amount of moisture in a rare earth metal oxide film manufactured on the surface of a substrate is reduced by using the method disclosed herein.

Brief Description of the Drawings

[0005] The accompanying drawings are included to provide a further understanding of the method and the substrate, form a part of this specification, show embodiments, and are useful for explaining the above principles in conjunction with the description of this specification.

[0006] [Figure 1] The test apparatus used in Example 1 is shown. [Modes for carrying out the invention]

[0007] The present invention provides a method for producing a rare earth metal oxide film on the surface of a substrate. The method involves, in a reaction space, Step a) involves exposing the deposited surface to an oxygen alcohol precursor to adsorb at least a portion of the oxygen alcohol precursor onto the deposited surface of the substrate, and then purging the deposited surface with an inert gas for a first period of 1 to 180 seconds. The method includes alternating between steps b) exposing the deposited surface to a rare earth metal precursor to adsorb at least a portion of the rare earth metal precursor onto the deposited surface of the substrate, and subsequently purging the deposited surface with an inert gas over a second period, in any order.

[0008] Furthermore, it is disclosed that the moisture content in a rare earth metal oxide film manufactured on the surface of a substrate can be reduced using the method disclosed herein.

[0009] The method may be used to produce a rare-earth metal oxide film on the surface of a substrate, the rare-earth metal oxide film having a uniform thickness. The thickness uniformity of the produced rare-earth metal oxide film can be measured, for example, using an ellipsometer. In this specification, unless otherwise specified, the terms “uniform thickness” or “thickness uniformity” can be interpreted as referring to a film having a thickness of 100 to 2000 nm that exhibits a thickness uniformity of ±5% throughout the entire film.

[0010] The inventors have surprisingly found that, in the method disclosed herein, the use of an oxygen alcohol precursor allows for the reduction or removal of moisture in the film during the manufacturing process, as well as the reduction of the period for purging the reaction space with an inert gas. Rare earth metal oxides are materials that readily bind to moisture, and this moisture may not be easily removed during the manufacturing process. Moisture bound to rare earth metal oxides has the adverse effect of causing uneven thickness in the manufactured film, resulting in an appearance that may make it unsuitable for further applications. Because rare earth metal oxides have the property of binding to moisture, the film growth rate increases, which can adversely affect the uniformity of thickness.

[0011] In this specification, unless otherwise specified, the terms “surface,” “substrate surface,” or “deposition surface” are used to refer to the surface of a substrate or the surface of a film, layer, or deposit already formed on the substrate. Therefore, the terms “surface,” “substrate surface,” and “deposition surface” include the surface of a substrate that has not been exposed to any precursor and the surface of a substrate that has been exposed to one or more precursors. Thus, the “deposition surface” changes during the deposition process when chemical substances are chemiadsorbed onto the surface.

[0012] The method is at least 40dm 3 , at least 100dm 3 or at least 150 dm 3 The process is carried out in an industrial-scale manner within a reaction space of a certain volume. The method disclosed herein has the additional utility of enabling the production of rare earth metal oxide films in large-scale industrial processes, whereas purging water or moisture from the reaction space after using water as an oxygen precursor is conventionally a slow process that leaves residual moisture in the film. The method disclosed herein has the additional utility of enabling the production of films with uniform thickness in large-scale processes while maintaining production time at an economically useful level.

[0013] In one embodiment, the method is up to 250 dm 3The reaction takes place in a reaction space of volume.

[0014] The growth rate of the rare earth metal oxide film may be 0.1-10 Å / deposition cycle, 0.3-2 Å / deposition cycle, or 0.5-1.5 Å / deposition cycle, and each deposition cycle may include or consist of a) and b). Surprisingly, the inventors have found that by using an alcohol-based precursor of oxygen, the growth rate of the film can be slowed, thereby enabling the production of rare earth metal oxide films of uniform thickness in a large-scale manufacturing process. The use of an alcohol-based precursor in the method has the desired effect of reducing the amount of water present in the manufactured film, which can adversely affect the uniformity of thickness.

[0015] The rare earth metal may be selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. In one embodiment, the rare earth metal is yttrium or europium.

[0016] According to the International Union of Pure and Applied Chemistry (IUPAC), lanthanides, in addition to yttrium and scandium, are also considered rare earth metals.

[0017] The rare earth metal oxide may be scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide, or any combination or mixture thereof. In one embodiment, the rare earth metal oxide is yttrium oxide.

[0018] The different precursors used in the methods for producing rare earth metal oxide films disclosed herein are generally available and will be apparent to those skilled in the art based on this specification.

[0019] In this specification, unless otherwise specified, the term “alcoholic precursor of oxygen” is used to refer to an organic compound containing a hydroxyl group consisting of an oxygen atom and a hydrogen atom on a carbon atom. Alcohols are represented by the general formula ROH, where R may be an alkyl group or a substituted alkyl group.

[0020] The alcohol-based precursor of oxygen may be a methanol-based precursor of oxygen, an ethanol-based precursor of oxygen, a propanol-based precursor of oxygen, an isopropanol-based precursor of oxygen, a butanol-based precursor of oxygen, a 2-butanol-based precursor of oxygen, or a tert-butanol-based precursor of oxygen. In one embodiment, the alcohol-based precursor of oxygen is selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, 2-butanol, and tert-butanol. In one embodiment, the alcohol-based precursor of oxygen is ethanol or isopropanol.

[0021] In one embodiment, the rare earth metal precursor is selected from the group consisting of scandium precursor, yttrium precursor, lanthanum precursor, cerium precursor, praseodymium precursor, neodymium precursor, samarium precursor, europium precursor, gadolinium precursor, terbium precursor, dysprosium precursor, holmium precursor, erbium precursor, thulium precursor, ytterbium precursor, and lutetium precursor.

[0022] The precursor of the rare earth metal may be a precursor containing a heteroleptic containing, for example, a cyclopentadienyl ligand, an amine ligand or both. As an example, tris(methylcyclopentadienyl)yttrium ((MeCp)3Y) and yttrium tris(N,N'-diisopropylacetamidinate) can be mentioned, but appropriate precursors of other rare earth metals may also be used.

[0023] The substrate may be formed of silicon, ceramic, metal and / or glass. In one embodiment, the substrate is formed of metal. The metal may be a porous metal. The glass may be a porous glass. In one embodiment, the substrate is formed of silicon.

[0024] In one embodiment, the alternating steps of a) and b) are repeated one or more times. The alternating steps of a) and b) may be repeated one or more times until the desired film thickness is reached. The method may include forming a film of rare earth metal oxide having a total thickness of 100 to 5000 nm, 150 to 4000 nm, 200 to 3000 nm, 300 to 2500 nm or 400 to 2000 nm.

[0025] The film of rare earth metal oxide may be produced on the surface of the substrate in the reaction space using an atomic layer deposition (ALD) type process. When the film of rare earth metal oxide is produced on the surface of the substrate using the ALD type process, the formed film can obtain excellent conformality and uniformity.

[0026] The ALD process is a method for depositing uniform, conformal deposits, layers, or films on substrates of various shapes, and even on complex three-dimensional structures. In the ALD process, the substrate is alternately exposed to at least two different precursors (chemical substances), usually one precursor at a time, and deposits, layers, or films are formed on the substrate by alternating, essentially self-limiting surface reactions between the substrate surface (and, in later stages, naturally, the surface of layers, deposits, or films already formed on the substrate) and the precursors. As a result, the deposited material "grows" on the substrate in molecular layers.

[0027] A distinctive feature of the ALD (Alternating Laser Deposition) process is that the surface to be deposited is alternately exposed to two or more different precursors, and typically a purge period exists between precursor pulses. During the purge period, the deposition surface is exposed to a flow of gas that does not react with the precursors used in the process. This inert gas, also called a carrier gas or purge gas, is inert to the precursors used in the process and removes, for example, excess precursors and by-products generated by chemiadsorption reactions of the previous precursor pulse. This purging can be carried out by various means. A fundamental requirement of the ALD process is to purge the deposition surface between the introduction of metallic and nonmetallic precursors. The purge period restricts vapor phase growth, ensuring that only surfaces exposed to the precursor gas participate in growth.

[0028] The purging of the deposit surface in a) may be performed by purging the deposit surface with an inert gas for a first period of 1 to 180 seconds, 1 to 120 seconds, 2 to 100 seconds, 3 to 60 seconds, 4 to 30 seconds, or 5 to 25 seconds. Surprisingly, the inventors have found that the purging time can be substantially reduced by using an alcohol-based precursor of oxygen. The reduction in purging time has the additional benefit of making the process more economical.

[0029] The purging of the reaction space in b) may be carried out by purging the deposition surface with an inert gas for a second period of 1 to 180 seconds, 1 to 120 seconds, 2 to 100 seconds, 3 to 60 seconds, 4 to 30 seconds, or 5 to 25 seconds.

[0030] Exposing the deposition surface to different precursors alternately or sequentially can be done in various ways. In a batch process, at least one substrate is placed in a reaction space where precursor gases and purge gases are introduced in predetermined cycles. Spatial atomic layer deposition (ALD) is an ALD-type process based on the spatial separation of precursor gases or vapors. While the substrate passes through, different precursor gases or vapors can be confined to specific process regions or zones. In a continuous ALD-type process, a moving substrate is used with spatially separated zones of constant gas flow to obtain time-series exposure. In the reaction space, a continuous coating process is realized by the substrate passing through fixed zones with precursor exposure regions and purge regions, enabling roll-to-roll coating of the substrate. In a continuous ALD-type process, the cycle time depends on the speed at which the substrate moves between the gas flow zones.

[0031] In these processes, names other than atomic layer deposition (ALD) are also used, and layers are often grown by substantially self-limiting surface reactions through the alternating introduction or exposure of two or more different precursors. These alternative names or process variations include atomic layer epitaxy (ALE), atomic layer chemical vapor deposition (ALCVD), and corresponding plasma-enhanced, photo-assisted, and electron-enhanced variations. Unless otherwise specified, these processes are collectively referred to as ALD-type processes in this specification.

[0032] The method disclosed herein has the additional benefit of being able to produce rare earth metal oxide films of uniform thickness under economically appropriate process conditions. The method disclosed herein has the additional benefit of being able to reduce the film growth rate. The method disclosed herein has the further additional benefit of being able to shorten the time required for purging the deposition surface. [Examples]

[0033] The embodiments described below will be referenced in detail.

[0034] The following description details several embodiments so that those skilled in the art can utilize the methods based on this disclosure. Not all steps of the embodiments are described in detail, as many steps are obvious to those skilled in the art based on this specification.

[0035] As described above, ALD processes are methods for depositing uniform and conformal films or layers on substrates of various shapes. Furthermore, as also described above, in ALD processes, layers or films grow by alternating substantially self-limiting surface reactions between a precursor and the surface to be coated. The prior art discloses many different apparatuses suitable for performing ALD processes. The configuration of a processing tool suitable for carrying out the methods of the following embodiments will be apparent to those skilled in the art in view of this disclosure. This tool may be, for example, a conventional ALD tool suitable for handling the chemicals of the process. Many steps related to handling such a tool, such as feeding the substrate into the reaction space, evacuating the reaction space to a low pressure, adjusting the gas flow within the tool when the process is carried out at atmospheric pressure, and heating the substrate and reaction space, will be apparent to those skilled in the art. Furthermore, in order to highlight relevant aspects of the various embodiments of the present invention, many other known operations or features are not described or mentioned in detail herein.

[0036] A rare earth metal oxide film can be fabricated on the surface of a substrate, as illustrated below. This exemplary embodiment can be fabricated by bringing the substrate into the reaction space of a typical reactor tool, for example, a tool suitable for running an ALD-type process, for example, as a batch process. The reaction space may then be evacuated to a pressure suitable for forming the rare earth metal oxide film, for example, using a mechanical vacuum pump. Alternatively, in the case of atmospheric pressure ALD systems and / or processes, the flow rate is usually set to protect the deposition zone from the atmosphere. The substrate can be heated to a temperature suitable for film formation by the method used. The substrate can be introduced into the reaction space, for example, via an airtight load lock system or simply via a loading hatch. The substrate can be heated in situ or exitu, for example, by a resistance heating element that heats the entire reaction space.

[0037] After the substrate and reaction space have reached the target temperature and other conditions suitable for deposition, the surface of the substrate can be conditioned so that different layers can be deposited substantially directly onto the surface. This surface conditioning typically involves chemical purification to remove impurities and / or oxides from the substrate surface. In particular, the removal of oxides is beneficial when the surface has been introduced into the reaction space via an oxidizing environment, such as when an exposed substrate is transferred from one deposition tool to another. Details of the process for removing impurities and / or oxides from the substrate surface will be apparent to those skilled in the art in light of this specification. In some embodiments of the present invention, this conditioning can be performed outside the apparatus suitable for the ALD type process, i.e., in the excituate. An example of an excituate conditioning process is etching with a 1% HF solution for 1 minute, followed by rinsing with deionized water. Another example of an excituate conditioning process is exposing the substrate to ozone gas or oxygen plasma to remove organic impurities from the substrate surface in the form of volatile gases.

[0038] After conditioning the surface of the substrate, the deposited surface is alternately exposed to different chemical substances to directly form a film of rare earth metal oxide on the substrate surface.

[0039] The precursor is appropriately introduced into the reaction space in a gaseous state. This can be achieved by first evaporating the precursor in each raw material container. The raw material container may or may not be heated, depending on the properties of the precursor chemical itself. The evaporated precursor can be introduced into the reaction space, for example, by administering it through piping of a reactor tool equipped with a channel for supplying the vaporized precursor into the reaction space. Controlled administration of vapor into the reaction space can be achieved by valves or other flow control devices installed in the channel. These valves are commonly called pulse valves in systems suitable for ALD-type deposition.

[0040] Other mechanisms for bringing the substrate into contact with the chemicals in the reaction space are also conceivable. One alternative is to move the surface of the substrate through the reaction space (instead of the evaporated chemicals), so that the substrate passes through the region occupied by the gaseous chemicals.

[0041] A reactor suitable for ALD-type deposition includes a system for introducing an inert gas, such as nitrogen or argon, into the reaction space, thereby purging excess chemicals and reaction byproducts from the reaction space before introducing the next chemical. This feature, combined with a controlled dosage of vaporized precursors, allows for alternating exposure of the substrate surface to precursors without significant mixing of different precursors within the reaction space or other parts of the reactor. In practice, the inert gas flow is continuous throughout the reaction space throughout the deposition process, with only different precursors being alternately introduced into the reaction space along with the carrier gas. Clearly, purging the reaction space does not necessarily completely remove excess precursors or reaction byproducts, and residues of these materials or other materials may always be present.

[0042] After various preparation steps, a rare earth metal oxide film is deposited on the deposition surface by repeatedly exposing it to surface reactions with selected precursors (one precursor at a time) until a predetermined film thickness is reached. This occurs in the reaction space, Step a) involves exposing the deposited surface to an oxygen alcohol precursor to adsorb at least a portion of the oxygen alcohol precursor onto the deposited surface of the substrate, and then purging the deposited surface with an inert gas for a first period of 1 to 180 seconds. This can be carried out by alternately performing step b) exposing the deposited surface to a rare earth metal precursor to adsorb at least a portion of the rare earth metal precursor onto the deposited surface of the substrate, and then purging the deposited surface with an inert gas for a second period.

[0043] Each time the deposition surface is exposed to a precursor, additional deposits are formed on the deposition surface as a result of the adsorption reaction between the corresponding precursor and the deposition surface. The thickness of the film on the substrate surface can be increased by repeating exposure to different precursors one or more times. The film thickness is increased until the target thickness is reached, and then the process is terminated by stopping the alternating exposures. As a result of this deposition process, a film of rare earth metal oxide is formed on the substrate surface.

[0044] The following example illustrates how a rare earth metal oxide film can be fabricated on the surface of a substrate.

[0045] (Example 1) Formation of rare earth metal oxide films on a substrate In this embodiment, a rare earth metal oxide film is formed on the surface of a substrate using an ALD-type process. The test apparatus used is shown in Figure 1. Substrate samples to be coated with the formed film were placed at different positions on two bowls arranged in the reaction chamber. The direction of gas flow is indicated by arrows. In this embodiment, Oxygen alcohol precursors: ethanol, Period 1 (Purge): 30s Rare earth metal precursor: (MeCp)3Y, Second period (purge): 30s, Substrate: Silicon, The parameter used was temperature: 250°C.

[0046] First, the deposition surface was exposed to ethanol for 1 second, followed by purging with an inert gas (N2) for a first period of 30 seconds. Next, the deposition surface was exposed to tris(methylcyclopentadienyl)yttrium ((MeCp)3Y) for 2 seconds, followed by purging with an inert gas (N2) for a second period of 30 seconds. After repeating this cycle 350 times, the process was stopped and the coated substrate was cooled to room temperature.

[0047] Comparative Example 1 was carried out in the same manner, except that water was used instead of ethanol as the oxygen precursor.

[0048] The thickness uniformity of the formed film was measured in the reaction chamber using polarization analysis. The measurement points are shown in Figure 1 (B1, B2, B3, B4, A1, A2, A3 and A4 are at the rim of the bowl, and B11, B22, B33, B44, BC, A11, A22, A33, A44 and AC are at the bottom of the bowl). The results are shown in the table below.

[0049] [Table 1]

[0050] The average thickness of Example 1 was 26.36 nm, with an RSD (Relative Standard Deviation) of 8.97% and a GPC (Growth per Cycle) of 0.075 nm / cycle. Similarly, the average thickness of Comparative Example 1 was 57.77 nm, with an RSD of 14.47% and a GPC of 0.165 nm / cycle.

[0051] From the above results, it can be seen that the GPC is lower in Example 1 than in Comparative Example 1. Furthermore, in the film of Example 1, the variation in thickness between different parts of the rare earth metal film is significantly smaller compared to the film of Comparative Example 1.

[0052] Those skilled in the art will see that, with advances in technology, the basic concepts may be implemented in various ways. Therefore, the embodiments are not limited to the examples described above, and instead, they may be modified within the scope of the claims.

[0053] The embodiments described above may be used in any combination. Several embodiments may be combined to form further embodiments. The methods or uses disclosed herein may include at least one of the embodiments described above. It should be understood that the benefits and advantages described above may relate to one embodiment or to several embodiments. Embodiments are not limited to solving any or all of the problems described or having any or all of the benefits and advantages described. Furthermore, it should be understood that a reference to an “an” item refers to one or more of those items. The term “including” is used herein to mean including a subsequent feature or action without excluding the presence of one or more additional features or actions.

Claims

1. A method for producing a rare earth metal oxide film on the surface of a substrate, wherein in a reaction space, Step a) involves exposing the deposited surface to an oxygen alcohol precursor to adsorb at least a portion of the oxygen alcohol precursor onto the deposited surface of the substrate, and then purging the deposited surface with an inert gas for a first period of 1 to 180 seconds. A method comprising alternating between steps b) exposing a deposited surface to a rare earth metal precursor to adsorb at least a portion of the rare earth metal precursor onto the deposited surface of the substrate, and subsequently purging the deposited surface with an inert gas for a second period, in any order.

2. The above method is at least 40 dm ３ , at least 100 dm ３ or at least 150 dm ３ The method according to claim 1, carried out in an industrial-scale manner within a reaction space of a certain volume.

3. The method according to any one of claims 1 to 2, wherein the growth rate of the rare earth metal oxide film is 0.1 to 10 Å / deposition cycle, 0.3 to 2 Å / deposition cycle, or 0.5 to 1.5 Å / deposition cycle, and each deposition cycle includes a) and b), or consists of a) and b).

4. The method according to any one of claims 1 to 3, wherein the alcohol-based precursor of oxygen is selected from the group consisting of a methanol-based precursor of oxygen, an ethanol-based precursor of oxygen, a propanol-based precursor of oxygen, an isopropanol-based precursor of oxygen, a butanol-based precursor of oxygen, a 2-butanol-based precursor of oxygen, and a tert-butanol-based precursor of oxygen.

5. The method according to any one of claims 1 to 4, wherein the rare earth metal precursor is selected from the group consisting of scandium precursor, yttrium precursor, lanthanum precursor, cerium precursor, praseodymium precursor, neodymium precursor, samarium precursor, europium precursor, gadolinium precursor, terbium precursor, dysprosium precursor, holmium precursor, erbium precursor, thulium precursor, ytterbium precursor, and lutetium precursor.

6. The method according to any one of claims 1 to 5, wherein the purging of the reaction space in a) is performed by purging the deposition surface with an inert gas for a first period of 1 to 120 seconds, 2 to 100 seconds, 3 to 60 seconds, 4 to 30 seconds, or 5 to 25 seconds.

7. The method according to any one of claims 1 to 6, wherein the purging of the reaction space in b) is carried out by purging the deposition surface with an inert gas for a second period of 1 to 180 seconds, 1 to 120 seconds, 2 to 100 seconds, 3 to 60 seconds, 4 to 30 seconds, or 5 to 25 seconds.

8. The method according to any one of claims 1 to 6, wherein the substrate is formed of silicon, ceramic, metal and / or glass.

9. The method according to any one of claims 1 to 8, wherein the film of the rare earth metal oxide is manufactured on the surface of the substrate in a reaction space by an atomic layer deposition process.

10. Use of the method according to any one of claims 1 to 9 for reducing the moisture content in the rare earth metal oxide film manufactured on the surface of a substrate.

11. The use according to claim 10, wherein the method is used to produce a rare earth metal oxide film on the surface of the substrate, and the rare earth metal oxide film has a uniform thickness.

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