Atomic layer deposition apparatus and atomic layer deposition method

Abstract

To provide a technology capable of improving an amount of adsorption of a raw material gas to a surface to be deposited in an ALD and improving a thickness uniformity coefficient of an oxide film formed on the surface to be deposited.SOLUTION: A showerhead H provided to face a surface to be deposited of an object to be deposited stored in a chamber includes: a gas supply surface H1 facing the surface to be deposited; and a raw material gas ejection hole h3 and oxidant gas ejection holes h1 and h2 provided on different circular virtual lines i in a plurality of circular virtual lines i concentrically positioned on the gas supply surface H1. The circular virtual line i having the raw material gas ejection hole h3 and the circular virtual line i having the oxidant gas ejection holes h1 and h2 are sequentially and alternately arranged toward an outer peripheral side from a central point i0 of each circular virtual line i, and the ejection holes h1-h3 are provided at a predetermined pitch in the circumferential direction on the respective circular virtual lines i.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an atomic layer deposition apparatus and an atomic layer deposition method, and relates to a technique for forming a thin film that can be applied to, for example, a semiconductor device. [Background technology]

[0002] Representative techniques for forming thin films (hereinafter simply referred to as film formation) for cutting-edge devices such as semiconductor devices (e.g., CPU circuits) include deposition, sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD). Among these, ALD is the most excellent in terms of step coverage and denseness, and is essential as a means for forming thin films for cutting-edge devices (e.g., Patent Document 1).

[0003] In ALD, four steps are mainly repeated: evacuating the entire chamber (vacuum vessel or the like) in which the object to be film-formed (e.g., silicon wafer) is placed, introducing the ALD source gas (e.g., TMA (trimethylaluminum)) into the chamber, removing the source gas from the chamber, and supplying an oxidizer for the source gas (e.g., water vapor) to the chamber. By introducing the source gas into the chamber and filling the chamber with the source gas, one molecular layer of the source gas is adsorbed onto the surface of the object to be film-formed (the surface to be film-formed), and a molecular layer of the source gas is formed on the surface to be film-formed of the object to be film-formed.

[0004] Then, by supplying an oxidizing agent of the source gas into the chamber, the molecular layer of the source gas formed on the film-forming surface is oxidized, and a molecular layer of an oxide film (e.g., aluminum oxide) of the source gas is formed on the film-forming surface. By repeating the above four steps, a thin film having a thickness according to the number of repetitions is formed.

[0005] The film formation process using ALD tends to require high film formation temperatures. For example, to fully react TMA with water vapor, the object on which the film is to be formed must be heated to a relatively high temperature (e.g., 300°C to 500°C). In addition, in the case of compound semiconductors such as GaN and ZnO used in cutting-edge devices, several thin-film semiconductor layers with slightly different compositions are sometimes formed on the film formation surface by heteroepitaxy or MBE (Molecular Beam Epitaxy). These thin-film semiconductor layers are strongly required to be formed at low temperatures because there is a risk of composition deviation occurring when heated.

[0006] Furthermore, for other cutting-edge devices, it is thought that a film formation temperature of room temperature to 100°C by ALD is preferable. Therefore, ALD that replaces the oxidizing agent with ozone (O3) or plasma oxygen and utilizes the radicals generated by the oxidizing agent is being considered. Ozone can generate O radicals, a powerful oxidizing agent, through thermal decomposition, making it possible to lower temperatures, but it is still necessary to heat the film-forming target to several hundred degrees Celsius. Even when using plasma oxygen, which is capable of supplying O radicals from the beginning and is considered to be the lowest possible temperature, the temperature can only be reduced to around 100°C to 150°C, and further reduction in temperature is required.

[0007] In addition, the conventional film formation process by ALD tends to have low film formation efficiency due to the long film formation time. For example, in order to form a monolayer film on a film formation surface by ALD, it is necessary to first perform a process of adsorbing a source gas on the film formation surface, removing the source gas, and oxidizing the source gas layer (adsorption layer) formed on the film formation surface. This process usually takes several minutes. For example, in the case of aluminum oxide, the thickness of one molecular layer is about 0.1 nm, so about 100 molecular layers are required to practically form a film of about 10 nm, and even if it takes 30 seconds per molecular layer, it takes about 50 minutes. For example, with other film formation methods such as CVD, a film of about 10 nm can be formed within 1 minute, so the long film formation time of ALD could be a major disadvantage compared to other film formation methods.

[0008] In recent years, a method of forming a film by efficiently supplying various gases such as source gases and oxidizing agents via a shower head and appropriately performing a film formation process by ALD has been investigated (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2014-057014 A [Patent Document 2] Patent No. 6677356 [Non-patent literature]

[0010] [Non-Patent Document 1] Press Release 2018 “World’s first technology to create oxide film at room temperature using pure ozone established”, [Online], July 31, 2019, Meidensha Corporation website, Internet, 〈https: / / www.meidensha.co.jp / news / news_03 / news_03_01 / 1227605_2469.html〉 Summary of the Invention [Problem to be solved by the invention]

[0011] The adsorption distribution and adsorption amount of the source gas change depending on the spray distribution and spray time of the source gas on the film formation surface. The film thickness distribution of the oxide film on the film formation surface and the number of film formation molecular layers in ALD are determined by the adsorption distribution and adsorption amount.

[0012] For this reason, for example, if the source gas is supplied into the chamber via a simple showerhead, it is possible that the thickness of the oxide film on the deposition surface will be uneven, particularly when the deposition temperature is below the ALD window temperature (the temperature at which molecular adsorption stabilizes at one molecular layer through self-regulation), and it may be difficult to achieve deposition by ALD at one molecular layer in areas with a low amount of adsorption.

[0013] The present invention has been made in consideration of the above circumstances, and aims to provide a technology that contributes to improving the amount of source gas adsorbed to the film-forming surface and improving the film thickness uniformity of the oxide film formed on the film-forming surface. [Means for solving the problem]

[0014] The atomic layer deposition apparatus and atomic layer deposition method according to the present invention can contribute to solving the above-mentioned problems, and one aspect of the atomic layer deposition apparatus includes a chamber capable of accommodating an object to be film-formed so that the object can be freely inserted and removed, a showerhead provided facing a surface to be film-formed of the object accommodated in the chamber, a gas supply unit that supplies gas into the chamber via the showerhead, and a gas exhaust unit that sucks in gas within the chamber and exhausts it outside the chamber, thereby maintaining a reduced pressure state within the chamber.

[0015] The showerhead includes a gas supply surface facing the film-forming surface, and raw material gas outlets and oxidant gas outlets provided on different circular imaginary lines among a plurality of circular imaginary lines positioned concentrically on the gas supply surface.

[0016] The circular imaginary lines in which the raw material gas ejection holes are provided and the circular imaginary lines in which the oxidant gas ejection holes are provided are alternately arranged in sequence from the center point of each circular imaginary line toward the outer periphery, and a plurality of raw material gas ejection holes and a plurality of oxidant gas ejection holes are provided at a predetermined pitch along the circumferential direction on each circular imaginary line, and the number of ejection holes provided on each circular imaginary line increases from the center point of each circular imaginary line toward the outer periphery.

[0017] The nozzle may also be characterized in that the nozzles are provided at positions offset from one another in the circumferential direction of each of the circular imaginary lines, with the radial imaginary lines extending from the center point toward the outer periphery as a reference.

[0018] The pitch of each circular imaginary line may be set to be equal to or greater than 1 / 2 and equal to or less than 2 times the shortest distance between the nozzle holes on each adjacent circular imaginary line.

[0019] The pitch of each of the circular imaginary lines may be set to be equal to or smaller than the distance between the film-forming surface and the gas supply surface.

[0020] In addition, it may be characterized in that, among the circular virtual lines in which the same type of ejection holes are provided, the difference in diameter between adjacent virtual lines is set to less than twice the distance between the film-forming surface and the gas supply surface.

[0021] Furthermore, among the circular virtual lines in which raw material gas ejection holes are provided, the circular virtual line located on the outermost side in the extension direction of the radial virtual lines extending from the center point toward the outer periphery may be positioned biased in the extension direction of the radial virtual lines relative to the outer periphery of the film-forming surface, and the raw material gas may be supplied from the ejection holes provided in the circular virtual line on the outermost side.

[0022] The gas supply unit may further include a source gas supply line that supplies a source gas into the chamber via a shower head, and an oxidant supply line that supplies at least ozone gas as an oxidant gas into the chamber via the shower head.

[0023] The raw material gas supply line may also be characterized in that it includes a raw material gas buffer section that can accumulate and seal the raw material gas in the raw material gas supply line by opening and closing a buffer section on-off valve provided in the raw material gas supply line and can supply the accumulated raw material gas into the chamber, and a raw material gas buffer section pressure gauge that measures the gas pressure in the raw material gas buffer section.

[0024] The raw material gas buffer section pressure gauge may also be characterized by having an upstream pressure gauge provided upstream of the raw material gas buffer section, and a downstream pressure gauge provided downstream of the buffer section opening / closing valve.

[0025] The gas supply device may further include a raw material gas amount control unit that controls the amount of raw material gas stored in the raw material gas buffer unit based on the amount of change in the measurement values ​​of the upstream pressure gauge and the downstream pressure gauge.

[0026] The raw material gas amount control unit may also be characterized in that it appropriately controls the amount of raw material gas based on a difference value obtained by subtracting the measurement value of the upstream pressure gauge when the buffer section opening / closing valve is in a closed state from the measurement value of the downstream pressure gauge in the closed state, the amount of change in the measurement value of the upstream pressure gauge when the buffer section opening / closing valve in the closed state is transitioned to an open state, the time for which the open state is maintained, and the volume of the raw material gas buffer section.

[0027] The raw material gas amount control unit may be characterized in that it sets the subtraction value within a range of 100 Pa or less, and controls the opening and closing of the buffer opening and closing valve so that a change in the measurement value of an upstream pressure gauge when the buffer section opening and closing valve in a closed state is transitioned to an open state is within 100 Pa.

[0028] The raw gas supply line may be provided downstream of the raw gas buffer section with an inert gas supply line that can be switched between a connected state and a cut-off state with respect to the raw gas supply line and that supplies an inert gas to the downstream of the raw gas buffer section.

[0029] One aspect of the atomic layer deposition method is a method of using the atomic layer deposition apparatus to form an oxide film on a film-forming surface of a film-forming object in a chamber of the atomic layer deposition apparatus, wherein the oxidant gas outlet of the atomic layer deposition apparatus includes an ozone gas outlet and an unsaturated hydrocarbon gas outlet, the ozone gas outlet and the unsaturated hydrocarbon gas outlet being provided on different adjacent circular imaginary lines, and the oxidant supply line includes an ozone gas supply line that supplies ozone gas into the chamber via a showerhead, and an unsaturated hydrocarbon gas supply line that supplies the unsaturated hydrocarbon gas into the chamber via the showerhead.

[0030] The method is characterized by having a raw material gas supplying process in which a raw material gas containing elements that constitute an oxide film is supplied into the chamber to form an adsorption layer of the raw material gas on the film-forming surface; a raw material gas purging process in which surplus gas of the raw material gas supplied in the raw material gas supplying process and gas generated by adsorption of the raw material gas on the film-forming surface are removed from the film-forming surface; an oxidant supplying process in which ozone gas and an unsaturated hydrocarbon gas are supplied into the chamber to oxidize the adsorption layer formed on the film-forming surface; and an oxidant purging process in which surplus gas of the ozone gas and the unsaturated hydrocarbon gas supplied in the oxidant supplying process and gas generated by oxidizing the adsorption layer of the raw material gas are removed from the film-forming surface.

[0031] Another aspect of the atomic layer deposition method is a method for forming an oxide film on a film-forming surface of an object in a chamber of the atomic layer deposition apparatus using the atomic layer deposition apparatus, the method comprising: a source gas supplying step of supplying a source gas containing elements that constitute an oxide film into the chamber, sealing the source gas, and forming an adsorption layer of the source gas on the film-forming surface; a source gas purging step of removing, from the film-forming surface, an excess of the source gas supplied in the source gas supplying step and a gas generated by the source gas being adsorbed on the film-forming surface; an oxidant supplying step of supplying 80 volume % or more of ozone gas into the chamber, sealing it, and oxidizing the adsorption layer formed on the film-forming surface; and an oxidant purging step of removing, from the film-forming surface, an excess of the ozone gas supplied in the oxidant supplying step and a gas generated by the oxidation of the adsorption layer of the source gas.

[0032] In addition, the method may be characterized in that a cycle of each of the steps of a raw material gas supply step, a raw material gas purging step, an oxidant supply step, and an oxidant purging step is performed multiple times, and different types of raw material gases are supplied to the object to be film-formed in at least one of the raw material gas supply steps and in the remaining steps.

[0033] The oxide film may also be characterized in that it includes an adsorption layer of any one of Al2O3, HfO2, TiO2, ZnO, Ta2O3, Ga2O3, MoO3, RuO2, SiO2, ZrO2, and Y2O3. Effect of the Invention

[0034] As described above, the present invention can contribute to improving the amount of source gas adsorbed onto the film-forming surface and improving the uniformity of the thickness of the oxide film formed on the film-forming surface. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a schematic diagram for explaining an example of the main configuration of an ALD apparatus in an embodiment. [Diagram 2] FIG. 2 is a schematic diagram for explaining an example of a shower head H (viewing a gas supply surface H1). [Diagram 3] FIG. 3 is an enlarged view showing a portion of FIG. 2 (mainly the portion indicated by the imaginary line i22). [Figure 4] FIG. 1 is a schematic diagram illustrating an example of the configuration of an ALD apparatus. [Diagram 5] FIG. 4 is a film formation process diagram for forming an oxide film 21. [Figure 6] FIG. 2 is a reaction schematic diagram showing an example of forming an oxide film 21 according to the first embodiment. [Figure 7] FIG. 4 is a characteristic diagram of pressure change with respect to elapsed time for explaining an example of a film formation cycle according to the first embodiment. [Figure 8] FIG. 6 is a reaction schematic diagram showing an example of forming an oxide film 21 according to Example 2. [Figure 9] FIG. 11 is a pressure change characteristic diagram for explaining an example of a film formation cycle according to the second embodiment. [Figure 10] 11A to 11C are various cross-sectional images for explaining the cross-sectional observation results of the oxide film 21 according to Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The atomic layer deposition apparatus and atomic layer deposition method (hereinafter appropriately referred to as the ALD apparatus and the ALD method) according to the embodiment of the present invention are completely different from, for example, a conventional ALD method (hereinafter appropriately referred to simply as the conventional ALD method) in which a source gas is supplied into a chamber via a simple showerhead.

[0037] That is, in the ALD apparatus and ALD method of the present embodiment, a shower head is provided facing a deposition surface of a deposition target housed in a chamber, the shower head including a gas supply surface facing the deposition surface, and a source gas ejection hole and an oxidant gas ejection hole each provided on a different circular imaginary line among a plurality of circular imaginary lines concentrically positioned on the gas supply surface.

[0038] The circular imaginary lines on which the raw material gas ejection holes are provided and the circular imaginary lines on which the oxidant gas ejection holes are provided are arranged alternately in sequence from the center point of each circular imaginary line toward the outer periphery. A plurality of raw material gas ejection holes and a plurality of oxidant gas ejection holes are provided at a predetermined pitch along the circumferential direction on each circular imaginary line, and the number of ejection holes provided on each circular imaginary line increases from the center point of each circular imaginary line toward the outer periphery.

[0039] Such a showerhead can improve the amount of source gas adsorbed onto the deposition surface, and can prevent unevenness in the thickness of the oxide film. This makes it easier to achieve the desired deposition of a single molecular layer by ALD.

[0040] For example, when ozone gas and unsaturated hydrocarbon gas are supplied to the chamber as the oxidant gas, the oxidant gas outlet of the showerhead includes an ozone gas outlet and an unsaturated hydrocarbon gas outlet. The ozone gas outlet and the unsaturated hydrocarbon gas outlet are provided on different adjacent circular imaginary lines, and the source gas outlet is provided on a circular imaginary line adjacent to the ozone gas outlet and the unsaturated hydrocarbon gas outlet (for example, as shown in FIG. 2 described later, the outlets h3 to h1 are provided on different imaginary lines in the order of the outlets h3 to h1 from the center point i0 of the imaginary lines i11 to i51 toward the outer periphery).

[0041] By appropriately supplying both ozone gas and unsaturated hydrocarbon gas to the chamber through such a showerhead, the reaction between the two produces OH *(OH radicals) are generated, making it possible to oxidize the source gas layer (adsorption layer) formed on the film formation surface.

[0042] On the other hand, when only ozone gas is used as the oxidizing gas, the oxidizing gas outlet of the shower head may be configured to have only ozone gas outlets. In this case, both the raw material gas outlets and the ozone gas outlets may be provided on different adjacent circular imaginary lines (for example, in the case of imaginary lines i11 to i51 shown in FIG. 2 described later, the outlets h1 and h3 are provided alternately on different imaginary lines from the center point i0 toward the outer periphery).

[0043] By supplying a high concentration of ozone gas (e.g., ozone gas of 80 volume % or more) into the chamber via such a showerhead (e.g., sealing the supplied ozone gas within the chamber), it is possible to sufficiently oxidize the raw material gas layer formed on the film formation surface without using the radicals generated by the oxidizer gas as described above.

[0044] In the ALD apparatus and the ALD method of the present embodiment, as described above, the raw material gas ejection holes and the oxidant gas ejection holes provided on different circular imaginary lines among the concentric circular imaginary lines of the gas supply surface are provided at a predetermined pitch along the circumferential direction on each circular imaginary line, and are provided at positions offset from each other in the circumferential direction of each circular imaginary line based on the radial imaginary lines extending from the center point of each circular imaginary line toward the outer periphery. That is, it is possible to appropriately apply technical common sense in various fields (for example, the field of film formation by ALD, CVD, etc., the field of modification, the field of chambers, the field of ozone gas, the field of supply lines, etc.) and appropriately refer to prior art documents, etc. as necessary to modify the design, and the following examples are given as examples.

[0045] In the following embodiments, detailed descriptions will be omitted as appropriate, for example, by referring to similar contents by the same reference numerals.

[0046] Example <Main configuration example of ALD apparatus 1> FIG. 1 shows an overview of an ALD apparatus 1 according to an embodiment. This ALD apparatus 1 includes a chamber (reaction vessel) 3 that can accommodate an object to be film-formed 2 in and out freely, a shower head H provided facing the film-forming surface 20 of the object to be film-formed 2 accommodated in the chamber 3, a gas supply unit 4 that supplies various gases (source gas, oxidizing agent gas, etc.) into the chamber 3 via the shower head H, and a gas discharge unit 5 that sucks the gas in the chamber 3 and discharges it outside the chamber 3.

[0047] The object to be film-formed 2 accommodated in the chamber 3 is appropriately supported by a support portion 31 in the chamber 3, and for example, the position is adjusted so that the center point of the film-forming surface 20 of the object to be film-formed 2 faces a center point h0 as shown in FIG. 2 described later.

[0048] The gas supply unit 4 includes, for example, an oxidizing agent supply line L (ozone gas supply line L1 and unsaturated hydrocarbon gas supply line L2 in FIG. 4), a source gas supply line L3 as shown in FIG. 4 described later, and is configured to supply an oxidizing agent gas (ozone gas and unsaturated hydrocarbon gas in FIG. 4) and a source gas into the chamber 3 via the shower head H from these oxidizing agent supply line L and source gas supply line L3.

[0049] The gas discharge unit 5 is provided, for example, at a position separated from the shower head H in the chamber 3 (a position on the side of the chamber 3 shown in FIG. 1). This gas discharge unit 5 sucks the gas in the chamber 3 and discharges it outside the chamber 3, and is configured to maintain the inside of the chamber 3 in a reduced pressure state (for example, a state where the inside of the chamber 3 is in a vacuum environment) or to seal the gas in the chamber 3. As a specific example of the gas discharge unit 5, in addition to the exhaust pipe 5a, a configuration having an on-off valve 5b, a vacuum pump 5c, etc. as shown in FIG. 4 described later can be mentioned. 1, the shower head H may be provided on a lid 6 that closes an opening of the chamber 3. In the case of the lid 6 shown in Fig. 1, pipes L11 and L12 of an oxidizing agent supply line L described below and a pipe L31 of a raw material gas supply line L3 described below are provided.

[0050] In the case of the showerhead H shown in FIG. 1, the showerhead H has a gas supply surface H1 facing the film formation surface 20, which is provided with nozzles h1 to h3 for spraying ozone gas, unsaturated hydrocarbon gas, and raw material gas supplied from a gas supply unit 4.

[0051] In addition, gas buffer spaces 6a to 6c are formed in the lid 6 for the ozone gas, unsaturated hydrocarbon gas, and raw material gas supplied from the gas supply unit 4, and the pressure and flow rate of the gas sprayed from each of the holes h1 to h3 of the showerhead H can be equalized by passing through these gas buffer spaces 6a to 6c.

[0052] <Shower head H> In the showerhead H, for example, one having a flat gas supply surface H1 as shown in FIG. 2 is applied, and as shown in FIG. 2, FIG. 3 and Table 1, oxidizer gas outlets (ozone gas outlets h1, unsaturated hydrocarbon gas outlets h2) and raw material gas outlets h3 are provided.

[0053] [Table 1]

[0054] 2 and other figures, a plurality of circular imaginary lines i11-i51 (hereinafter, collectively referred to simply as imaginary lines i as necessary) having different diameters are depicted concentrically on the gas supply surface H1. The ejection holes h1-h3 are provided on different imaginary lines i.

[0055] Each virtual line i provided with ejection holes h1 to h3 is arranged so as to repeat in the order of h3 to h1 from the center point i0 of each virtual line i toward the outer peripheral side. And the number of ejection holes h1 to h3 provided on each virtual line i is set to increase as it approaches the outer peripheral side from the center point i0 of each virtual line i.

[0056] Specifically, in the number n of ejection holes shown in Table 1, it can be mentioned that it is set to increase in the ascending order shown in Table 1 (set to satisfy the relationship of n11 < n12 < n13 < …… < n42 < n43 < n51). Also, in the diameter φ and the circumferential length C of the virtual line shown in Table 1, it can be mentioned that it is similarly set to increase in the ascending order shown in Table 1.

[0057] By applying such a shower head H, each gas (raw material gas, oxidant gas) ejected from the ejection holes h1 to h3 on the gas supply surface can be easily and uniformly dispersed and sprayed onto the film formation surface 20, and the adsorption amount of the raw material gas to the film formation surface is also likely to be improved, etc., and such an effect will be achieved.

[0058] For the purpose of more easily exhibiting such an effect, etc., the shower head H may be appropriately redesigned, and examples of such changes are as shown below.

[0059] For example, the ejection holes h1 to h3 provided on each virtual line i are preferably provided at positions offset from each other in the circumferential direction of the virtual line i (positions not coinciding on the same radial virtual line) with respect to a radial virtual line (not shown) extending from the center point h0 of each virtual line i toward the outer peripheral side.

[0060] Also, a plurality of ejection holes h1 to h3 are provided at a predetermined pitch d along the circumferential direction (circumferential length C direction in FIG. 3) of each virtual line i as shown in FIGS. 2 and 3 (in FIG. 3, only the content related to the virtual line i22 is depicted as a representative), and it can be mentioned that the number of the ejection holes h1 to h3 is provided to increase as it approaches the outer peripheral side from the center point h0 of the virtual line i.

[0061] Moreover, the pitch d of each of the holes h1-h3 provided on each virtual line i can be set to be between 1 / 2 and 2 times the shortest distance t between the holes on the adjacent virtual lines i (for example, in the case of FIG. 3, the shortest distance t between the hole h2 on the virtual line i22 and the hole h1 on the virtual line i23). Alternatively, the pitch d on each virtual line i can be set to be less than the distance between the film-forming surface 20 and the gas supply surface H1 (hereinafter simply referred to as the film-forming surface gap).

[0062] For each virtual line i, the diameter difference between adjacent virtual lines i can be set within a range of 10 mm to 20 mm. As a result, for example, among virtual lines on which the same type of nozzle holes h1 to h3 are provided (for example, virtual lines i11, i21, i31, i41, and i51 on which nozzle hole h3 is provided), the diameter difference between adjacent virtual lines (for example, virtual lines i11 and i21) is within a range of 30 to 60 mm. Therefore, if the film-formed surface gap is 30 mm, the diameter difference between adjacent virtual lines can be set to less than twice the film-formed surface gap.

[0063] Further, the outermost virtual line i (the virtual line i51 in FIG. 2; hereinafter, simply referred to as the outermost virtual line) is provided with an ejection hole h3. This outermost virtual line may be set to be positioned more offset in the extension direction of the radial virtual lines than the outer periphery of the deposition surface 20. Specifically, the diameter of the outermost virtual line may be set to be equal to or larger than the diameter of the deposition surface 20 (for example, 0 to 22 mm larger). It is desirable to supply raw material gas from the ejection hole h3 provided on this outermost virtual line.

[0064] The shapes of the nozzle holes h1 to h3 are not particularly limited, but examples include circular, elliptical, rectangular, and slit-shaped openings, and opening diameters that are appropriately set within the range of 0.5 to 1 mm.

[0065] The ejection holes h1 to h3 may be formed not only simply on the virtual line i of the gas supply surface H1, but also appropriately provided at locations other than the virtual line i. As an example, any one of the ejection holes h1 to h3 may be provided at the center point h0.

[0066] <Specific configuration example of the ALD apparatus 1> FIG. 4 illustrates a specific configuration example of the ALD apparatus 1. In the ALD apparatus 1 of FIG. 4, the gas supply unit 4 includes an oxidant supply line L that supplies at least ozone gas as an oxidant gas into the chamber 3 via a shower head H, and a source gas supply line L3 that supplies a source gas into the chamber 3 via the shower head H.

[0067] In the case of the oxidant supply line L in FIG. 4, an ozone gas supply line L1 that supplies ozone gas (for example, ozone gas of 80% by volume or more) of the ozone gas generator G1 into the chamber 3 via a shower head H, and an unsaturated hydrocarbon gas supply line L2 that supplies unsaturated hydrocarbon gas of the unsaturated hydrocarbon gas supply device G2 into the chamber 3 via the shower head H are provided.

[0068] <Ozone gas supply line L1, unsaturated hydrocarbon gas supply line L2> The ozone gas supply line L1 includes a pipe L11 that connects between the ozone gas generator G1 and the shower head H and is capable of supplying ozone gas of the ozone gas generator G1. This pipe L11 includes an on-off valve V1 that can switch the gas flow in the pipe L11 between a flowable state (open state) and a flow-blocking state (closed state).

[0069] The unsaturated hydrocarbon gas supply line L2 includes a pipe L21 that connects between the unsaturated hydrocarbon gas supply device G2 and the shower head H and is capable of supplying unsaturated hydrocarbon gas of the unsaturated hydrocarbon gas supply device G2. This pipe L21 includes an on-off valve V2 that can switch the gas flow in the pipe L21 between a flowable state (open state) and a flow-blocking state (closed state).

[0070] <Raw material gas supply line L3> The raw material gas supply line L3 includes a pipe L31 that connects the raw material gas supply device G3 and the shower head H and can supply the raw material gas of the raw material gas supply device G3. The pipe L31 includes a raw material gas on-off valve V2 (a buffer on-off valve V3a located downstream of a raw material gas buffer section L32 described later in FIG. 1 and an on-off valve V3b located downstream of the on-off valve V3a) that can switch the gas flow in the pipe L31 between a flow-allowing state (open state) and a flow-blocking state (closed state), and a raw material gas buffer section L32 that can accumulate and seal the raw material gas (the raw material gas located upstream of the chamber 3) in the raw material gas supply line L2 by opening and closing the on-off valve V3 and can supply the accumulated raw material gas into the chamber 3.

[0071] The pipe L31 is provided with an upstream pressure gauge P that is located upstream of the buffer section L32 and is capable of measuring the gas pressure in the buffer section L32. 3a and a downstream pressure gauge P located downstream of the buffer section L32 and capable of measuring the downstream gas pressure. 3b In the case of the pipe L21 in Fig. 1, an inert gas supply line L4, which will be described later, is also provided.

[0072] <Inert gas supply line L4> The inert gas supply line L4 is provided with an inert gas pipe L41 that connects the inert gas supply device G4 and the downstream side of the buffer section L32 in the raw material gas supply line L3 and can supply the inert gas of the inert gas supply device G3. The pipe L41 is provided with an on-off valve V4 (in FIG. 4, the on-off valve V4 is located downstream of a mass flow controller L42 described later) that can switch the gas flow in the pipe L41 between a flow-enabling state (open state) and a flow-blocking state (closed state), and a mass flow controller L42 that can control the gas flow rate in the pipe L41.

[0073] In such an inert gas supply line L4, for example, by appropriately opening and closing the on-off valve V4 and appropriately controlling the supply amount of the inert gas from the inert gas supply device G4 by the mass flow controller L42, the inert gas can be supplied from the downstream side of the buffer section L32 in the raw material gas supply line L3 into the chamber 3. This makes it possible to supply the inert gas as a carrier gas for the raw material gas or as a purge gas in various purge processes.

[0074] <Shut-off valves V1 to V4> Various aspects can be applied to the on-off valves V1 to V4, and are not particularly limited, but examples include an automatic on-off structure, a high-speed on-off structure, a three-way valve structure, etc. In the case of Fig. 4, a three-way valve structure is applied to the on-off valve V3a of the raw material gas supply line L3, and the inert gas supply line L4 is connected to the downstream side of the buffer section L32 in the raw material gas supply line L3 via the on-off valve V3a. In the case of the on-off valve V3a in Fig. 4, "△" in the figure indicates that the inert gas from the inert gas supply line L4 is always in a flowable state, and "▲" in the figure indicates the location where the opening and closing operation is performed.

[0075] <Buffer section L32> The buffer section L32 is not particularly limited as long as it can receive the source gas flowing through the pipe L31, appropriately store it at a predetermined pressure, and appropriately supply the source gas at the predetermined pressure into the chamber 3. As an example, the volume of the buffer section L32 is about 1 / 50 or more of the volume of the chamber 3 (as a specific example, when the volume of the chamber 3 is 10000 cc or less, the volume of the buffer section L32 is 1000 cc or less, and as a further specific example, when the volume of the chamber 3 is 7000 cc, the volume of the buffer section L32 is 250 cc), and the gas pressure in the buffer section L32 can be maintained at a predetermined pressure.

[0076] The amount of the source gas stored in the buffer portion L32 (the amount of the source gas supplied into the chamber 3) is, for example, measured by a source gas amount control portion (not shown in the figure, which will be described in detail later) using a pressure gauge P 3a ,P3b It is possible to control based on the amount of change in the measured value, etc. (Specific control examples will be described later).

[0077] In such a raw material gas supply line L3, for example, the on-off valve V3 is appropriately opened and closed to measure the gas pressure in the buffer section L32 with a pressure gauge P 3a ,P 3b By appropriately controlling based on this, it becomes possible to accumulate the source gas at a predetermined pressure and a predetermined concentration in the buffer portion L32 and supply the source gas into the chamber 3.

[0078] After this raw material gas is supplied into chamber 3, the raw material gas remaining in buffer section L32 can be stored in buffer section L32 and used again (can be supplied again into chamber 3) during the next raw material gas storage operation, together with new raw material gas from raw material gas supply device G3.

[0079] When the raw material gas accumulated in the buffer section L32 is supplied to the chamber 3, the buffer section L32 and the chamber 3 are in communication with each other. However, depending on the piping pressure loss, it may take a long time for the pressure between the two sections to reach an equilibrium state.

[0080] In such a case, the gas pressure in the buffer section L32 (e.g., the pressure of the mixed gas of the raw material gas and the carrier gas) may be increased, or the gas supply to the chamber 3 may be temporarily stopped before the equilibrium state is reached, and the pressure in the chamber 3 may be maintained, while continuing to expose the film formation surface 20 to the raw material gas as appropriate.

[0081] In addition, a plurality of source gas supply lines L3 may be provided in parallel with respect to the chamber 3, but when the vapor pressures of the source gases in the source gas supply lines L3 are different from each other, the temperature in each source gas supply line L3 may be adjusted by, for example, a temperature adjustment unit (for example, a temperature adjustment unit having a heating mechanism such as a thermocouple or an infrared heater) not shown in the figure. For example, when there are two source gas supply lines L2 for supplying TMA and TDMAT as described later as source gases, the temperatures in the pipes L21 may be adjusted to 50° C. and 150° C., respectively.

[0082] The temperature adjusting unit may be configured to adjust the temperature of other components in addition to simply adjusting the temperature of the source gas supply line L3. For example, as shown in FIG. 4, the temperature of the components within the region surrounded by the two-dot chain line may be adjusted.

[0083] <Configuration example of raw material gas amount control section> The raw material gas amount control section is, for example, a pressure gauge P 3a ,P 3b An example of a controllable configuration is one in which the change in the measurement value or the difference in the measurement value (pressure difference between the buffer section L32 and the downstream side of the buffer section L32) is monitored, and the vapor pressure of the raw material gas or the amount of inert gas from the inert gas supply line L4 is adjusted based on the monitoring results, so that the difference in the measurement value can be appropriately adjusted.

[0084] For example, in the case of the ALD apparatus 1 shown in FIG. 4, first, the “▲” portion of the on-off valve V3a is closed, and the inert gas is steadily supplied from the inert gas supply line L4 into the chamber 3. 3a From the measured value α of the pressure gauge P 3b The subtraction value α-β obtained by subtracting the measured value β from the measured value α satisfies α-β>0. From this state, when the "▲" part of the on-off valve V3a is opened, the pressure gauge P 3a The measured value α of the

[0085] Therefore, in the raw material gas amount control section, when the on-off valve V3a is switched to the open state as described above (hereinafter, simply referred to as the time of switching to the open state), 3a The amount of change in the measured value α and the time during which the open state is maintained are integrated, and the amount of raw material gas can be appropriately controlled based on the integrated value and the volume of the buffer section L32.

[0086] For example, when the volume of the chamber 3 is 10000 cc or less, the volume of the buffer section L32 is 1000 cc or less, and the raw material gas is supplied into the chamber 3 using an inert gas as a carrier gas, the raw material gas amount control section controls the pressure gauge P at the time of transition to the open state while keeping the difference value α-β within a range of 100 Pa or less. 3a One example of the time for which the on-off valve V3a is held in the open state during the transition to the open state is appropriately set so that the amount of change in the measured value α falls within a range of 100 Pa or less.

[0087] Specifically, when the volume of the chamber 3 is 500 cc and the volume of the buffer unit L32 is 100 cc, the raw material gas amount control unit is set so that the difference value α-β is 40 Pa and the pressure gauge P 3a The change in the measured value α was controlled to be 10 Pa, and the time during which the on-off valve V3a was held in the open state during the open state transition was controlled to be 0.1 seconds. When the source gas (for example, TMA described later) stored in the buffer unit L32 was appropriately supplied into the chamber 3, the amount of the source gas was approximately 10 -5 At this time, the pressure change in the chamber 3 was also appropriately measured by the pressure gauge P, and the change in the measured value was about 0.01 Pa.

[0088] In addition, pressure gauge P 3a The measured value α of the pressure gauge P is adjusted according to the vapor pressure of the raw material gas, and is appropriately set (for example, appropriately subtracted according to the concentration) so as to be the measured value for the raw material gas having a concentration of approximately 100% by volume. 3a ,P 3b The pressure range is appropriately selected to increase the decimal place of the measurement value that can be monitored.

[0089] According to the above-mentioned confirmation results, in the source gas amount control section of the ALD apparatus 1 as shown in FIG. 3a It was found that by appropriately controlling the amount of source gas based on the change in the measured value α of the pressure gauge P, it is possible to precisely control the amount of source gas even if the amount is very small (for example, 1 cc or less). In addition, it was also confirmed that it is difficult to control the amount of source gas by the pressure gauge P, which measures the pressure change in the chamber 3, because the measured value of the pressure gauge P is relatively small.

[0090] <An example of the film-forming target 2> The object 2 to be film-formed may be any object capable of forming the desired oxide film 21 on the surface 20 to be film-formed by appropriately operating the ALD apparatus 1, and examples of such object include a solid, a substrate, a powder (e.g., an aggregate of a large number of particulate objects 2 to be film-formed), a film, a sheet, a cloth, a fiber, and the like.

[0091] Furthermore, in the method of forming an oxide film using a raw material gas and a relatively high concentration (80 volume % or more) ozone gas, the oxide film can be formed at a relatively low temperature. Therefore, in the case of a substrate or film, for example, the substrate is not limited to a substrate having a relatively high heat resistance such as a Si substrate, and the oxide film can also be formed on a substrate made of a synthetic resin having a relatively low heat resistance.

[0092] When the film-forming target 2 is made of a resin, examples of the resin include polyester resin, aramid resin, olefin resin, polypropylene, PPS (polyphenylene sulfide), PET (polyethylene terephthalate), and the like.

[0093] Other examples include those using PE (polyethylene), PEN (polyethylene naphthalate), POM (polyoxymethylene or acetal resin), PEEK (polyether ether ketone), ABS resin (acrylonitrile, butadiene, styrene copolymer synthetic resin), PA (polyamide), PFA (tetrafluoroethylene, perfluoroalkoxyethylene copolymer), PI (polyimide), PVD (polyvinyl dichloride), etc.

[0094] The film-forming surface 20 of the film-forming object 2 is not limited to being simply flat, and may be in various forms. For example, the film-forming object 2 shown in Fig. 10 described later has a film-forming surface 20 having uneven steps formed by a plurality of trench grooves 22.

[0095] Furthermore, the temperature of the film-forming object 2 may be appropriately adjusted by heating or cooling using a temperature adjustment unit not shown, for example, for the purpose of improving the film-forming performance. As a specific example, the temperature may be adjusted as necessary so that the film-forming temperature of the film-forming surface 20 is within the range of about room temperature to 100°C.

[0096] <An example of the support portion 31> The support portion 31 for supporting the film-formation target object 2 accommodated in the chamber 3 may be of any type as long as it can support the film-formation target object 2 without interfering with film formation on the film-formation surface 20, and is not particularly limited.

[0097] <An example of the gas exhaust section 5> The exhaust by gas exhaust part 5 may be performed in any manner as long as it can maintain the reduced pressure state inside chamber 3 as described above, and is not particularly limited.

[0098] 4, the gas exhaust unit 5 includes an exhaust pipe 5a, an on-off valve 5b, a vacuum pump 5c, etc., but may also include an ozone killer (abatement equipment such as an abatement tube that decomposes ozone; not shown), etc. It is preferable that the vacuum pump 5c is resistant to ozone (for example, a dry pump).

[0099] In addition, a plurality of exhaust lines may be provided in the gas exhaust section 5, and each of the exhaust lines may be used in each of the steps S1 to S4. This makes it possible to distribute the gas exhausted in each of the steps S1 to S4 to a dedicated detoxification facility for treatment.

[0100] <Examples of raw gas> The raw material gas may include, as a constituent element, an element that forms an oxide film (e.g., lithium (Li), magnesium (Mg), silicon (Si), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), yttrium (Y), zirconium (Zr), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), indium (In), tin (Sn), hafnium (Hf), tantalum (Ta), tungsten (W), iridium (Ir), platinum (Pt), lead (Pb), etc.; hereinafter, these elements are referred to as metals or metal elements).

[0101] For example, a source gas containing an organosilicon having a Si-O bond or a Si-C bond, or an organometallic having a metal element-oxygen bond or a metal element-carbon bond, or a source gas such as an organometallic complex or a silicon or metal hydride may be used.

[0102] More specifically, examples of the method include those using silane (general term for hydrogen silicide), TEOS (Tetraethyl Orthosilicate), TMS (Trimethylsilane), TES (Triethylsilane), TMA (Trimethylaluminium), TEMAZ (Tetrakis(ethylmethylamino)zirconium), 3DAMAS (Tri-dimethylamino-silane; SiH[N(CH3)2]3), TDMAT (Tetrakis-dimethylamino-titanium; Ti[N(CH3)2]4), TDMAH (Tetrakis-dimethylamino-hafnium; Hf[N(CH3)2]4), etc. as the source gas. In addition, examples of the method include those using heterodinuclear complexes containing not only one type of metal element but also multiple types of metal elements (for example, complexes described in JP-A-2016-210742, etc.).

[0103] <An example of ozone gas> Ozone gas of various concentrations can be applied, but the higher the ozone concentration, the more preferable. Specifically, in the high-concentration ozone gas, the ozone concentration (volume % concentration) is preferably 80 to 100 volume %. Such a high-concentration ozone gas can be obtained by liquefying and separating only ozone from an ozone-containing gas based on the difference in vapor pressure, and then vaporizing the liquefied ozone again.

[0104] Examples of the ozone gas generator G1 include those disclosed in the patent documents of JP 2001-304756 A and JP 2003-20209 A. Such an ozone gas generator G1 liquefies and separates only ozone based on the difference in vapor pressure between ozone and other gases (e.g., oxygen) to generate high-concentration ozone (ozone concentration ≒ 100% by volume). In particular, if a plurality of chambers for liquefying and vaporizing only ozone are provided, high-concentration ozone gas can be continuously supplied by individually controlling the temperature of these chambers.

[0105] An example of a commercially available device that generates high-concentration ozone gas is the Pure Ozone Generator (MPOG-HM1A1) manufactured by Meidensha.

[0106] <Example of unsaturated hydrocarbon gas> As the unsaturated hydrocarbon gas, a hydrocarbon (alkene) having a double bond, such as ethylene, or a hydrocarbon (alkyne) having a triple bond, such as acetylene, is preferably used. As the unsaturated hydrocarbon, in addition to ethylene and acetylene, a low molecular weight unsaturated hydrocarbon such as propylene or butylene (for example, an unsaturated hydrocarbon having a carbon number n of 4 or less) is preferably used. When an unsaturated hydrocarbon gas containing these unsaturated hydrocarbons is reacted with a raw material gas or a high concentration ozone gas, it is preferable that the moisture content in the unsaturated hydrocarbon gas is small. This is because if the gas to be reacted contains a lot of moisture, dust may be generated due to the reaction between the moisture and the raw material gas. For example, it is preferable to use an unsaturated hydrocarbon gas having an atmospheric dew point (frost point) of -50°C or less (atmospheric pressure 1013.25 hPa) calculated based on JIS Z 8806. Similarly, it is preferable to use a gas having an atmospheric dew point (frost point) of -50°C or less as a purge gas, which will be described in detail later.

[0107] <Examples of inert gas> The inert gas may be any gas that can be used in the source gas purge step S2 or the oxidant purge step S4 described below, or can be used as a carrier gas for the source gas. Examples of such gases include inert gases such as N2, Ar, and He.

[0108] Example 1: An example of a film formation process using ALD apparatus 1 By appropriately operating various supply lines L1 to L4 of the ALD apparatus 1 and sequentially performing a source gas supply step S1, a source gas purge step S2, an oxidant supply step S3, and an oxidant purge step S4 shown in Fig. 5 as described below, a reaction such as that shown in the reaction schematic diagram of Fig. 6 occurs in the chamber 3. Then, the reaction makes it possible to form a desired oxide film 21 on a film formation surface 20 of a film formation target object 2 in the chamber 3. For convenience, this Example 1 will be described first based on the oxidant supply step S3 and the oxidant purge step S4, and then based on the source gas supply step S1 and the source gas purge step S2.

[0109] 6(a), the oxidizing agent supply step S3 (first time) is performed in advance, so that the ozone gas from the ozone gas generator G1 and the unsaturated hydrocarbon gas from the unsaturated hydrocarbon gas supply device G2 are supplied into the chamber 3 through the shower head H from the ozone gas supply line L1 and the unsaturated hydrocarbon gas supply line L2, respectively. * acts on the surface 20 on which the film is to be formed, and bonding sites (OH groups) for film formation are uniformly formed on the surface 20 on which the film is to be formed.

[0110] Then, in the oxidant purge step S4, the gas in the chamber 3 is sucked in and discharged by the gas exhaust part 5. As a result, the ozone gas and the excess gas of the unsaturated hydrocarbon gas supplied in the oxidant supply step S3 and the reaction gas (OH * etc.) are exhausted to the outside of the chamber 3. In the oxidizer purging step S4, if impurities or the like are attached to the film-forming surface 20 of the film-forming object 2, it is preferable to clean the film-forming surface 20 (for example, by supplying an inert gas from an inert gas supply device G3 through an inert gas supply line L4 to the chamber 3 to purge) in a stage prior to the raw material gas supplying step S1 to make the film-forming surface 20 more likely to adsorb the raw material gas.

[0111] Next, in the raw material gas supply step S1, the raw material gas (raw material gas containing elements constituting the target oxide film 21) from the raw material gas supply device G3 is supplied through the raw material gas supply line L3 into the chamber 3 via the shower head H. As a result, as shown in Fig. 6(b), the raw material gas is adsorbed onto the film formation surface 20 of the film formation target object 2 in the chamber 3, and an adsorption layer 21a of the raw material gas is formed. Fig. 6(b) depicts a state in which one molecular layer of TMA gas is adsorbed onto the film formation surface 20 of the substrate-like film formation target object 2.

[0112] After the raw material gas supply step S1, in the raw material gas purge step S2, the gas in the chamber 3 is sucked in and exhausted by the gas exhaust part 5. As a result, the surplus gas of the raw material gas supplied in the raw material gas supply step S1 and the gas generated by the raw material gas being adsorbed on the film formation surface 20 are exhausted to the outside of the chamber 3.

[0113] Then, the oxidizing agent supplying step S3 (second time) is carried out, and ozone gas and unsaturated hydrocarbon gas are supplied into the chamber 3 in the same manner as in the oxidizing agent supplying step S3 (first time), whereby OH is generated by the reaction between ozone and ethylene. * This results in the formation of OH * The oxidizing agent oxidizes the methyl groups (CH3) on the deposition surface 20 (the adsorption layer 21a), and bonding sites (OH groups) for the source gas for the next film formation are uniformly formed on the deposition surface 20. This oxidation reaction can be carried out even at room temperature (25°C).

[0114] By appropriately repeating the cycle of steps S1 to S4 as described above (hereinafter simply referred to as a film formation cycle), it is possible to form an oxide film 21 of a desired thickness on the film formation surface 20. Various film formation conditions in this film formation cycle can be appropriately set according to, for example, the desired oxide film 21.

[0115] Furthermore, when the film formation cycle is performed multiple times, for example, by supplying different types of raw material gas to the film formation target 2 in at least one of the raw material gas supply steps S1 and the remaining steps, it is possible to form a multi-layered oxide film 21 (i.e., an oxide film 21 in which multiple adsorption layers 21a are stacked) consisting of adsorption layers 21a of different raw material gases.

[0116] For example, when multiple raw gas supply lines L3 are provided in parallel to the chamber 3, each raw gas supply line L3 is adapted to supply a different type of raw gas, and one of the raw gas supply lines L3 is selectively operated (to supply raw gas) for each film formation cycle, thereby making it possible to form an oxide film 21 having a desired multilayer structure.

[0117] <Specific example of film formation cycle in Example 1> The supply amounts of the raw material gas, ozone gas, unsaturated hydrocarbon gas, and inert gas supplied to the chamber 3 via the shower head H, as well as the pressure of each of these gases (for example, the pressure (partial pressure) of the ozone gas in the chamber 3), can be appropriately controlled and set. One example of this is setting them taking into consideration the type, shape, and number of the objects 2 to be film-formed in the chamber 3, and the type and concentration of each of the gases.

[0118] As a specific example, when a film formation cycle is performed by each step S1 to S4 as shown in FIG. 7, the supply amount of each gas is appropriately set so that the process pressure in the chamber 3 during the film formation cycle falls within a range of 1000 Pa or less. More specifically, the pressure in the chamber 3 per one film formation cycle (3 to 20 seconds) is appropriately controlled so as to have a pressure fluctuation characteristic as shown in FIG. 7. In the case of the pressure in the chamber 3 shown in FIG. 7, the oxidizing agent supply step S3 (the state shown in FIG. 6(a)(c)) is 1000 Pa or less, and the source gas supply step S1 (the state shown in FIG. 6(b)) is controlled to 10 Pa or less (and the supply time is 1 second or less) as shown in the partial enlarged view of FIG. 7 (the blow-out view on the right side of the figure). In addition, the supply time of the ozone gas and the unsaturated hydrocarbon gas per one film formation cycle is 0.1 seconds or more.

[0119] By appropriately controlling the pressure fluctuation and the source gas supply time in the source gas supply step S1 as described above, the amount of the source gas adsorbed onto the film-forming surface 20 of the film-forming object 2 can be controlled.

[0120] For example, the amount of inert gas supplied by the inert gas supply line L4 may be appropriately changed during the film formation cycle, for example, for the purpose of controlling the amount of the source gas adsorbed to the film formation surface 20. For example, the film formation cycle may include a first step of supplying a predetermined flow rate (for example, 1 SLM or less) of inert gas as a carrier gas, and a second step of stopping the supply of the carrier gas in the first step (for example, for a few seconds) and then restarting the supply of the inert gas at a flow rate (for example, more than 1 SLM) higher than that in the first step. By appropriately performing the first and second steps (for example, alternately repeating them), it is possible to remove, for example, an excess amount of the source gas adsorbed to the film formation surface 20 from the film formation surface 20.

[0121] In order to reduce the gas residence time in the chamber 3, the exhaust from the gas exhaust section 5 can be constantly exhausted (the inside of the chamber 3 is in a reduced pressure atmosphere state) and the inert gas can be intermittently supplied as a purge gas through the inert gas supply line L4 (for example, at 1 SLM or less).

[0122] <Example 2: Another example of a film formation process using the ALD apparatus 1> In the oxidant supply step S3 of the first embodiment, both ozone gas and unsaturated hydrocarbon gas are applied as the oxidant gas supplied into the chamber 3, but the application of the unsaturated hydrocarbon gas may be omitted and only ozone gas may be applied. Specifically, by the ALD method in which the steps S1 to S4 shown in Fig. 5 are sequentially performed as described below, a reaction such as that shown in the reaction schematic diagram of Fig. 8 occurs in the chamber 3, and a desired oxide film 21 can be formed on the film formation surface 20 of the film formation target object 2 in the chamber 3.

[0123] First, in the raw material gas supply step S1, a raw material gas (a raw material gas containing elements constituting a target oxide film 21) from a raw material gas supply device G3 is supplied into the chamber 3 via a shower head H through a raw material gas supply line L3. As a result, as shown in the reaction schematic diagram of Fig. 8(a), the raw material gas is adsorbed onto the film formation surface 20 of the film formation target object 2 in the chamber 3, and an adsorption layer 21a of the raw material gas is formed. Fig. 8(a) depicts a state in which one molecular layer of TMA gas is adsorbed onto the film formation surface 20 of the substrate-like film formation target object 2.

[0124] After the raw material gas supply step S1, in the raw material gas purge step S2, an inert gas from an inert gas supply device G4 is supplied into the chamber 3 via the shower head H through the inert gas supply line L4, and the gas in the chamber 3 is sucked and exhausted through the gas exhaust part 5. As a result, the surplus gas of the raw material gas supplied in the raw material gas supply step S1 and the gas generated by the raw material gas being adsorbed on the film formation surface 20 are removed from the film formation surface 20.

[0125] Next, in the oxidizing agent supply step S3, ozone gas from an ozone gas generator G1 is supplied into the chamber 3 through the shower head H by an ozone gas supply line L1. As a result, as shown in the reaction schematic diagram of FIG. 8(b), the adsorption layer 21a formed on the deposition surface 20 is oxidized (the methyl group (CH3) is oxidized in FIG. 8), and an adsorption region 20a for the next deposition is formed on the deposition surface 20. The oxidation reaction shown in the reaction schematic diagram of FIG. 8(b) is possible even at room temperature (25° C.).

[0126] In the oxidant purge step S4, similarly to the source gas purge step S2, an inert gas from an inert gas supply device G4 is supplied into the chamber 3 via the shower head H through the inert gas supply line L4, and the gas in the chamber 3 is sucked and exhausted through the gas exhaust part 5. This removes from the deposition surface 20 the surplus ozone gas supplied in the oxidant supply step S3 and the gas generated by oxidizing the adsorption layer 21a of the source gas.

[0127] By appropriately repeating the film formation cycle including the above-described steps S1 to S4, it is possible to form an oxide film 21 of a desired thickness on the film formation surface 20, similarly to Example 1. Various film formation conditions in this film formation cycle can be appropriately set according to, for example, the desired oxide film 21.

[0128] Furthermore, when the film formation cycle is performed multiple times, for example, by supplying different types of raw material gas to the film formation target 2 in at least one of the raw material gas supply steps S1 and the remaining steps, it is possible to form a multi-layered oxide film 21 (i.e., an oxide film 21 in which multiple adsorption layers 21a are stacked) consisting of adsorption layers 21a of different raw material gases.

[0129] For example, when multiple raw gas supply lines L2 are provided in parallel to the chamber 3, each raw gas supply line L2 is adapted to supply a different type of raw gas, and one of the raw gas supply lines L2 is selectively operated (to supply raw gas) for each film formation cycle, thereby making it possible to form an oxide film 21 having a desired multilayer structure.

[0130] <Specific example of film formation cycle in Example 2> As a specific example of the film formation cycle in the second embodiment, an example as shown in FIG. 9 is performed according to the following items [1] to [8]. Item [1]: Vacuum exhaust inside the chamber 3 (gas inside the chamber 3 is sucked in by the gas exhaust part 5 to draw a vacuum) Item [2]: Implementing the oxidant supply process S3 (supplying only ozone gas as the oxidant gas into chamber 3 and sealing it). Item [3]: Implementing the oxidizer purge process S4 (supplying inert gas into chamber 3 and evacuating it) Item [4]: ​​Evacuate chamber 3 Item [5]: Implementing the source gas supply process S1 (supplying source gas into chamber 3 and sealing it) Item [6]: Evacuate chamber 3 Item [7]: Implementing the raw gas purge process S2 (supplying inert gas into chamber 3 and evacuating it) Item [8]: Evacuate chamber 3 (corresponding to item [1] in the next cycle).

[0131] The accumulation of the source gas in the buffer section L32 is preferably performed in any of the items [1] to [8] other than the item [5]. However, when an inert gas is supplied to the source gas supply line L3 through the inert gas supply line L4 and the inert gas is used as a carrier gas for the source gas, the accumulation is preferably performed in any of the items [3], [5], and [7] other than the items [1] to [8].

[0132] In addition, each of the steps [3] and [7] may be performed once in a film formation cycle, or may be performed multiple times (cycle purge). By performing each of the steps [3] and [7] multiple times, it may become easier to suppress the gas-phase mixing of the ozone gas and the source gas.

[0133] Example 3: Film formation using ALD apparatus 11 In the ALD apparatus 1 described above, a film formation cycle was performed based on Example 1 (when ozone gas and unsaturated hydrocarbon gas were used as the oxidant gas) and Example 2 (when only ozone gas was used as the oxidant gas), and the film thickness (nm) of the oxide film 21 formed on each of the opening edge surface 22a and the bottom surface 22b of the trench groove 22 was observed cross-sectionally, and the observation results are shown in FIG. 10.

[0134] In the observation conditions, the gap between the deposition surfaces was 30 mm, the diameter difference between adjacent virtual lines i was within the range of 16 mm to 20 mm, and the diameter of the outermost virtual line was 208 mm. Furthermore, the shortest distance t between adjacent virtual lines i of the nozzle holes h1 to h3 was within the range of 18.8 to 27.5 mm, and the opening diameter of the nozzle holes h1 to h3 was within the range of 0.5 to 1 mm.

[0135] The volume of the chamber 3 is 7000 cc, the volume of the buffer section L32 is 250 cc, the subtraction value α-β is 40 Pa, and the pressure gauge P 3a The change in the measured value α was set to 14 Pa, and the time for which the on-off valve V3a was held in the open state during the open state transition was set to 0.1 seconds. TMA, ethylene, and Ar were used as the raw material gas, unsaturated hydrocarbon gas, and inert gas, respectively, and the film-forming target 2 was a Si substrate with a diameter of 200 mm on which a trench groove 22 with a depth of 140 μm and an opening width of 3.5 μm was formed on the film-forming surface 20.

[0136] 10, it can be seen that oxide films 21 of sufficient thickness are formed on the opening edge surface 22a and the bottom surface 22b by the film formation cycles of Examples 1 and 2. In particular, the film thicknesses of the oxide films 21 formed on the opening edge surface 22a and the bottom surface 22b by the film formation cycle of Example 2 are 119 nm and 78 nm, respectively, which is thicker than the oxide film 21 by the film formation cycle of Example 1, and it can be seen that the aspect ratio (film thickness of oxide film 21 on bottom surface 22b / film thickness of oxide film 21 on opening edge surface 22a) is higher.

[0137] That is, according to the film formation cycle of Example 2, for example, by increasing the ozone gas concentration in item [2], it was found that the number of ozone molecules that reach the inner part of the trench groove 22 is increased, and the formation of the oxide film 21 on the bottom surface 22b of the trench groove 22 can be sufficiently promoted. In particular, it was found that the high-concentration (80 to 100% by volume) ozone gas obtained once through a liquefaction process has few contaminating impurities such as heavy metals, and therefore not only can the impurities in the oxide film 21 be reduced, but also that an improvement in the coverage of the oxide film 21 on the trench groove 22 can be expected.

[0138] The ALD method and ALD apparatus of the present invention have been described above by showing specific embodiments. However, the ALD method and ALD apparatus of the present invention are not limited to the embodiments, and appropriate design changes are possible without impairing the characteristics of the apparatus. Design changes also fall within the technical scope of the present invention. [Explanation of symbols]

[0139] 1...ALD equipment 2...Object to be film-formed, 20...Surface to be film-formed, 20a...Adsorption possible area, 21...Oxide film, 21a...Adsorption layer, 22...Trench groove 3. Chamber 4. Gas supply section 5...Gas exhaust section H: Shower head h1~h3…Blowout hole L…Oxidant supply line L1…Ozone gas supply line L2: Unsaturated hydrocarbon gas supply line L3: Raw gas supply line L4…Inert gas supply line G1: Ozone gas generator, G2: Unsaturated hydrocarbon gas supply device, G3: Raw material gas supply device, G4: Inert gas supply device

Claims

1. A chamber capable of accommodating an object to be film-formed, a shower head provided opposite to a film-forming surface of an object housed in the chamber; a gas supply unit that supplies a gas into the chamber through a shower head; a gas exhaust unit that sucks in gas within the chamber and exhausts it to the outside of the chamber, thereby maintaining a reduced pressure state within the chamber; A method for forming an oxide film on a film-forming surface of a film-forming object in a chamber of an atomic layer deposition apparatus, comprising: In the atomic layer deposition apparatus, the shower head comprises: a gas supply surface facing the deposition surface; a source gas outlet and an oxidant gas outlet provided on different circular imaginary lines among a plurality of circular imaginary lines concentrically positioned on the gas supply surface; Equipped with the circular imaginary lines in which the raw material gas ejection holes are provided and the circular imaginary lines in which the oxidant gas ejection holes are provided are alternately arranged in order from the center points of the respective circular imaginary lines toward the outer periphery, a plurality of raw material gas ejection holes and a plurality of oxidant gas ejection holes are provided at a predetermined pitch along a circumferential direction on each of the circular imaginary lines; the number of ejection holes provided on each of the circular imaginary lines increases from the center point of each of the circular imaginary lines toward the outer periphery, The gas supply unit is a source gas supply line that supplies a source gas into the chamber via a shower head; an oxidant supply line that supplies at least ozone gas as an oxidant gas into the chamber via a shower head; Equipped with a source gas supplying step of supplying a source gas containing elements constituting an oxide film into a chamber, sealing the source gas, and forming an adsorption layer of the source gas on a film-forming surface; a raw material gas purging step for removing from the deposition surface an excess gas of the raw material gas supplied in the raw material gas supplying step and a gas generated by the raw material gas being adsorbed on the deposition surface; an oxidant supplying step of supplying ozone gas into the chamber, sealing the ozone gas, and oxidizing the adsorption layer formed on the film formation surface; an oxidant purging step for removing from the deposition surface the excess ozone gas supplied in the oxidant supplying step and the gas generated by oxidizing the adsorption layer of the source gas; 1. An atomic layer deposition method comprising:

2. A chamber capable of accommodating an object to be film-formed and allowing it to be freely inserted and removed; a shower head provided opposite to a film-forming surface of an object housed in the chamber; a gas supply unit that supplies a gas into the chamber through a shower head; a gas exhaust unit that sucks in gas within the chamber and exhausts it to the outside of the chamber, thereby maintaining a reduced pressure state within the chamber; A method for forming an oxide film on a film-forming surface of a film-forming object in a chamber of an atomic layer deposition apparatus, comprising: In the atomic layer deposition apparatus, the shower head comprises: a gas supply surface facing the deposition surface; a source gas outlet and an oxidant gas outlet provided on different circular imaginary lines among a plurality of circular imaginary lines concentrically positioned on the gas supply surface; Equipped with the circular imaginary lines in which the raw material gas ejection holes are provided and the circular imaginary lines in which the oxidant gas ejection holes are provided are alternately arranged in order from the center points of the respective circular imaginary lines toward the outer periphery, a plurality of raw material gas ejection holes and a plurality of oxidant gas ejection holes are provided at a predetermined pitch along a circumferential direction on each of the circular imaginary lines; the number of ejection holes provided on each of the circular imaginary lines increases from the center point of each of the circular imaginary lines toward the outer periphery, The gas supply unit is a source gas supply line that supplies a source gas into the chamber via a shower head; an oxidant supply line that supplies at least ozone gas as an oxidant gas into the chamber via a shower head; Equipped with The oxidant gas outlet of the atomic layer deposition apparatus includes an ozone gas outlet and an unsaturated hydrocarbon gas outlet, the ozone gas outlet and the unsaturated hydrocarbon gas outlet are provided on different adjacent circular imaginary lines, The oxidant supply line is an ozone gas supply line that supplies ozone gas into the chamber via a shower head; an unsaturated hydrocarbon gas supply line that supplies an unsaturated hydrocarbon gas into the chamber through a showerhead; Equipped with a source gas supplying step of supplying a source gas containing elements constituting an oxide film into a chamber, sealing the source gas, and forming an adsorption layer of the source gas on a film-forming surface; a raw material gas purging step for removing from the deposition surface an excess gas of the raw material gas supplied in the raw material gas supplying step and a gas generated by the raw material gas being adsorbed on the deposition surface; an oxidant supplying step of supplying ozone gas and an unsaturated hydrocarbon gas into the chamber, sealing the ozone gas and the unsaturated hydrocarbon gas, and oxidizing the adsorption layer formed on the film formation surface; an oxidant purging step for removing from the deposition surface the ozone gas and the excess unsaturated hydrocarbon gas supplied in the oxidant supplying step and the gas generated by oxidizing the adsorption layer of the source gas; 1. An atomic layer deposition method comprising:

3. The atomic layer deposition method according to claim 1, wherein the concentration of ozone gas supplied into the chamber by the oxidizer supply step is 80 volume % or more.

4. Each nozzle is 4. The atomic layer deposition method according to claim 1, wherein the circular imaginary lines are provided at positions offset from each other in a circumferential direction with respect to the radial imaginary lines extending from the center point toward the outer periphery.

5. 5. The atomic layer deposition method according to claim 1, wherein the pitch in each circular imaginary line is set to be greater than or equal to 1 / 2 and less than or equal to 2 times the shortest distance between the nozzles on each adjacent circular imaginary line.

6. 6. The atomic layer deposition method according to claim 1, wherein the pitch of each of the circular imaginary lines is set to be equal to or smaller than the distance between the deposition surface and the gas supply surface.

7. 7. The atomic layer deposition method according to claim 1, wherein a difference in diameter between adjacent circular imaginary lines in which the same type of nozzle holes are provided is set to be equal to or less than twice the distance between the deposition surface and the gas supply surface.

8. Among the circular imaginary lines on which the source gas ejection holes are provided, a circular imaginary line located on the outermost side of the extension direction of the radial imaginary lines extending from the center point toward the outer periphery side is positioned to be biased in the extension direction of the radial imaginary lines from the outer periphery side of the film formation surface, 8. The atomic layer deposition method according to claim 1, wherein a source gas is supplied from ejection holes provided on the circular imaginary line on the outermost periphery.

9. The raw gas supply line is a raw material gas buffer section that can store and seal the raw material gas in the raw material gas supply line by opening and closing a buffer section on-off valve provided in the raw material gas supply line and can supply the stored raw material gas into the chamber; a raw material gas buffer pressure gauge for measuring a gas pressure in the raw material gas buffer; 9. The atomic layer deposition method according to claim 1, further comprising:

10. The raw gas buffer pressure gauge is an upstream pressure gauge provided upstream of the raw material gas buffer section; 10. The atomic layer deposition method according to claim 9, further comprising: a downstream pressure gauge provided downstream of the buffer section on-off valve.

11. The atomic layer deposition method of claim 10, characterized in that the atomic layer deposition apparatus further comprises a raw material gas amount control unit that controls the amount of raw material gas accumulated in the raw material gas buffer unit based on the change in the measurement values ​​of the upstream pressure gauge and the downstream pressure gauge.

12. The raw material gas amount control unit includes: a difference obtained by subtracting the measurement value of the downstream pressure gauge in the closed state from the measurement value of the upstream pressure gauge in the closed state of the buffer section opening / closing valve; and a change in the measurement value of the upstream pressure gauge when the buffer section opening / closing valve is opened from the closed state; and A time for which the open state is maintained, The volume of the raw gas buffer section and 12. The atomic layer deposition method according to claim 11, further comprising appropriately controlling the amount of the source gas based on the above.

13. 13. The atomic layer deposition method according to claim 12, wherein the source gas amount control unit controls the opening and closing of the buffer section opening and closing valve so that the subtraction value is within a range of 100 Pa or less and a change in the measurement value of an upstream pressure gauge when the buffer section opening and closing valve in a closed state is switched to an open state is within 100 Pa.

14. 14. The atomic layer deposition method according to claim 9, further comprising an inert gas supply line, which is switchable between a communicating state and a cutoff state with respect to the raw material gas supply line, downstream of the raw material gas buffer section in the raw material gas supply line, and supplies an inert gas to the downstream of the raw material gas buffer section.

15. 15. The atomic layer deposition method according to claim 1, wherein a cycle of each of a source gas supply step, a source gas purging step, an oxidant supply step, and an oxidant purging step is performed a plurality of times, and different types of source gases are supplied to the film formation target in at least one of the source gas supply steps and in the remaining steps.

16. The oxide film is Al ２ O ３ , HfO ２ , TiO ２ , ZnO, Ta ２ O ３ , Ga ２ O ３ , MoO ３ , RuO ２ , SiO ２ , ZrO ２ , Y ２ O ３ 16. The atomic layer deposition method according to claim 1, further comprising an adsorption layer of any one of the following:

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