Film formation method and film formation apparatus

Abstract

The objective is to provide a film-forming method and apparatus that can manufacture large-area, high-quality thin films with a homogeneous composition with high productivity. [Solution] A film-forming method in which a raw material mist obtained by atomizing a raw material solution is mixed with a carrier gas to form a mixed gas, which is supplied from the upstream of the substrate so as to flow in one direction along the main surface of the substrate, and exhausted downstream of the substrate in the same direction, thereby forming a film on the substrate by a thermal reaction, wherein additional mixed gas is supplied at the upstream position on the substrate.

Description

Technical Field

[0001] The present invention relates to a film-forming method and a film-forming apparatus.

Background Art

[0002] As a method capable of forming an epitaxial film or the like at low temperature and atmospheric pressure, a film-forming technique using water fine particles such as the mist CVD method is known. In Patent Document 1, a film-forming apparatus is shown in which a raw material mist is supplied to a substrate from a nozzle disposed at an inclination with respect to the substrate to form a film. In Patent Document 2, a film-forming apparatus is shown in which a raw material mist is ejected from a slit-shaped nozzle and the mist is caused to flow inside a wind guiding member provided in parallel with a substrate to be conveyed to form a film.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the film-forming apparatus as in Patent Document 1, the control of the raw material mist on the substrate could not be sufficiently performed. As a result, it was almost impossible to form a film with a uniform thickness on a large-diameter substrate of a practical size, and there were also problems such as adhesion of foreign substances such as powder generated by turbulent flow of the mist and abnormal growth, making it very difficult to form a high-quality film.

[0005] Furthermore, in film-forming apparatuses like the one described in Patent Document 2, the mist concentration is generally highest directly below the nozzle from which the mist is discharged, and decreases exponentially toward the recovery port. Therefore, if the desired film thickness cannot be obtained with a single mist supply, it was necessary to repeat the mist supply by sweeping the substrate or nozzle back and forth. However, in this case, the mist supply onto the substrate becomes intermittent, resulting in low productivity. In addition, when the nozzle is swept back and forth, the mist flow can easily become turbulent depending on the sweep distance, which has the disadvantage of easily creating a film thickness distribution.

[0006] Furthermore, in cases where film formation is performed using raw materials with a multi-component composition, such as when multiple types of raw materials are individually atomized and supplied to the substrate, the composition ratio of the raw material mist changes between the area near the mist ejection section and below the air guide member due to differences in physical properties such as the boiling point of each raw material mist, resulting in the problem that a homogeneous film cannot be formed.

[0007] The present invention has been made to solve the above problems and aims to provide a film-forming method and apparatus that can produce large-area, high-quality thin films with a homogeneous composition with high productivity. [Means for solving the problem]

[0008] The present invention was made to achieve the above objective, and provides a film-forming method for forming a film on a substrate by thermal reaction, in which a mixture formed by mixing a raw material mist obtained by atomizing a raw material solution with a carrier gas is supplied from the upstream of the substrate so as to flow in one direction along the main surface of the substrate, and exhausted from the downstream of the substrate in the same direction, wherein the film-forming method is provided in which the mixture is additionally supplied at the upstream position on the substrate.

[0009] With this film-forming method, regardless of the physical properties of the raw materials used, high-quality films with homogeneous thickness and composition can be stably produced with high productivity, even on large-area substrates.

[0010] In this case, the additional supply can be controlled by controlling the supply amount for each type of raw material mist contained in the mixture.

[0011] This makes it easier to produce homogeneous films even when using raw material solutions with different physical properties simultaneously.

[0012] In this case, the additional supply can be performed at multiple locations on the upward-facing side.

[0013] This makes it possible to manufacture more homogeneous films.

[0014] The present invention has also been made to achieve the above objectives, and provides a film-forming apparatus comprising: atomizing means for atomizing a raw material solution to generate a raw material mist; carrier gas supply means for supplying a carrier gas for conveying the raw material mist; flow rate adjustment unit for adjusting the flow rate of the carrier gas, or a mixture of the raw material mist and the carrier gas; nozzle unit having a plurality of discharge ports for supplying the mixture; mounting unit for mounting a substrate; heating means for heating the substrate; and exhaust means for exhausting the mixture supplied to the substrate from the nozzle unit, wherein the nozzle unit supplies the mixture from the upstream of the substrate so that it flows in one direction along the main surface of the substrate; the exhaust means exhausts the mixture downstream of the substrate in the one direction; and the nozzle unit supplies additional mixture at a position on the substrate upstream of the one direction.

[0015] With this type of film-forming apparatus, regardless of the physical properties of the raw materials used, it becomes possible to stably produce high-quality films with homogeneous thickness and composition, even on large-area substrates, with high productivity.

[0016] In this case, the plurality of discharge ports may have slit-shaped openings and be arranged parallel to the long axis of the opening and spaced apart in the short axis direction.

[0017] As a result, it becomes possible to more easily and stably produce a uniform film even on a large-area substrate.

[0018] At this time, it can be configured such that a quadrilateral having both ends of each of the two slit-shaped discharge ports at the most distant positions covers the mounting region of the substrate on the mounting portion.

[0019] As a result, it becomes possible to more stably produce a uniform film.

Advantages of the Invention

[0020] As described above, according to the film forming method of the present invention, regardless of the physical properties of the raw materials used, a high-quality film with uniform film thickness and composition can be stably produced with high productivity even on a large-area substrate. Further, according to the film forming apparatus of the present invention, regardless of the physical properties of the raw materials used, a high-quality film with uniform film thickness and composition can be stably produced with high productivity even on a large-area substrate.

Brief Description of the Drawings

[0021] [Figure 1] A schematic diagram of an example of a film forming apparatus according to a first embodiment of the present invention is shown. [Figure 2] A schematic diagram of an example of a film forming apparatus according to a second embodiment of the present invention is shown. [Figure 3] A side cross-sectional view of an example of a nozzle unit according to the present invention is shown. [Figure 4] A view of the bottom surface of an example of a nozzle unit according to the present invention as seen from the substrate side is shown. [Figure 5] It is a diagram showing the in-plane distribution of the [Al] / [Ga] ratio in Example 2 and Comparative Example 2.

Modes for Carrying Out the Invention

[0022] Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

[0023] As described above, there was a need for a film deposition apparatus and method that could produce large-area, high-quality thin films with a homogeneous composition with high productivity.

[0024] As a result of diligent study on the above problems, the inventors have found that a film-forming method is provided in which a mixture formed by mixing a raw material mist obtained by atomizing (hereinafter also referred to as "misting") a raw material solution with a carrier gas is supplied from the upstream of the substrate so as to flow in one direction along the main surface of the substrate, and exhausted from the downstream of the substrate in the same direction, thereby forming a film on the substrate by thermal reaction, wherein the mixture is supplied additionally at the upstream position on the substrate, regardless of the physical properties of the raw materials used, and high-quality films with homogeneous thickness and composition can be stably produced with high productivity even on large-area substrates, and the present invention has been completed.

[0025] The inventors have also conducted extensive research on the above-mentioned problems and have found a solution comprising: an atomizing means for atomizing a raw material solution to generate a raw material mist; a carrier gas supply means for supplying a carrier gas for transporting the raw material mist; a flow rate adjustment unit for adjusting the flow rate of the carrier gas, or a mixture of the raw material mist and the carrier gas; a nozzle unit having a plurality of discharge ports for supplying the mixture; a mounting unit for mounting a base; a heating means for heating the base; and an exhaust means for exhausting the mixture supplied from the nozzle unit to the base. The present invention was completed by discovering that a film-forming apparatus, wherein the nozzle unit supplies the mixed gas from upstream of the substrate so that it flows in one direction along the main surface of the substrate, the exhaust means exhausts the mixed gas downstream of the substrate in the one direction, and the nozzle unit supplies additional mixed gas at a position on the substrate upstream of the one direction, can stably produce high-quality films with homogeneous thickness and composition even on large-area substrates, regardless of the physical properties of the raw materials used, with high productivity.

[0026] [Film forming equipment] The film-forming apparatus of the present invention will be described below with reference to Figures 1 to 4. Figure 1 shows a schematic diagram of an example of a film-forming apparatus according to the first embodiment of the present invention. As shown in Figure 1, the film-forming apparatus 100 according to the present invention comprises a carrier gas supply means 111 for supplying a carrier gas to transport raw material mist 122, a carrier gas pipe 112, a flow rate adjustment unit 140, an atomizing means (hereinafter also referred to as "atomizing device") 120, a mist pipe 124, a nozzle unit 130 for supplying a mixed gas 133, a mounting unit (hereinafter also referred to as "stage") 151, an exhaust means 160, and a heating means 170, and a substrate 152 on which a film is formed is placed on the stage 151.

[0027] Multiple atomizing devices 120 are provided, and each atomizing device 120 is individually connected to a carrier gas pipe 112 and a flow rate control unit 140. The flow rate control unit 140 controls the amount of carrier gas supplied to each atomizing device 120.

[0028] (Flow rate adjustment part) The flow rate adjustment unit 140 has the function of adjusting the flow rate of the carrier gas, or the mixed gas 123 which is a mixture of the raw material mist 122 and the carrier gas.

[0029] The flow rate adjustment unit 140 is not particularly limited as long as it is a control device that can stably obtain the desired flow rate, and a known flow rate regulator can be used, for example, a flow meter or a mass flow controller can be used. Furthermore, when supplying the mixed gas 123 at the same flow rate from multiple atomizers 120, it is possible to control all of the multiple atomizers 120 together with a single flow rate adjustment unit, but since the amount of atomization often differs due to differences between each atomizer 120, it is preferable in the present invention to provide a flow rate adjustment unit 140 for each atomizer 120.

[0030] Although Figure 1 shows a configuration in which the flow rate adjustment unit 140 is located before the atomizer 120, the present invention is not limited to this configuration, and the flow rate adjustment unit 140 may be located after the atomizer 120.

[0031] (Atomization means) The atomizing means (atomizing device) 120 has the function of atomizing the raw material solution 121 to generate raw material mist 122.

[0032] The atomizing device 120 may also be equipped with a temperature control unit, which is not shown in the figure. This temperature control unit may directly or indirectly adjust the temperature of the raw material solution 121, and may perform heat exchange using a liquid or gaseous heat transfer medium, or it may apply the Peltier effect. A wide range of known heat transfer mediums can be used as the heat transfer medium, and liquids such as water, glycols, alcohols, and silicone oils, or gaseous heat transfer mediums such as air, helium, or fluorocarbons are preferably used.

[0033] Each atomizer 120 is supplied with carrier gas after its flow rate has been adjusted by the flow rate adjustment unit 140, and it is mixed with the raw material mist 122 to form a mixture 123. The mixture 123 is supplied to the nozzle unit 130 through the mist piping 124. In other words, in the configuration shown in Figure 1, a set consisting of the flow rate adjustment unit 140, atomizer 120, and mist piping 124 forms one system for supplying the raw material mist 122, and each system supplies the mixture 123 to the nozzle unit 130.

[0034] Figure 1 illustrates a configuration in which a mixed gas 123 is supplied from a single atomizer 120 in a single mist supply system. However, the present invention is not limited to this configuration, and a configuration in which a mixed gas 123 is supplied from multiple atomizers 120 in a single mist supply system is also possible.

[0035] Figure 2 shows an example of a film-forming apparatus 200 according to a second embodiment of the present invention, in which two atomizers 120 are arranged in a single mist supply system. In this case, carrier gas with individually controlled flow rates is supplied to the two atomizers 120A and 120B in a single mist supply system, and the mixtures 123a and 123b of raw material mist 122 atomized in each atomizer 120A and 120B and carrier gas merge in the connected mist piping 124 and are supplied to the nozzle unit 130.

[0036] In the configuration shown in Figure 2, atomizers 120A and 120B are connected by a mist pipe 124. Therefore, the mixture 123a generated by atomizer 120A and the mixture 123b generated by atomizer 120B are mixed in the mist pipe 124. However, the present invention is not limited to this configuration, and the mixture 123a and 123b may be supplied directly to a nozzle unit 130 and mixed inside the nozzle unit 130.

[0037] (Mist piping) The mist piping 124 is not particularly limited as long as it has sufficient stability against temperature at the connection between the raw material solution 121 used, the nozzle unit 130, and the transport piping, and can be made of resin, metal, glass, or a combination thereof depending on the purpose.

[0038] (Nozzle unit) The nozzle unit 130 supplies the mixed gas 123 from each mist supply system from the upstream side of the base body 152 so that it flows in one direction along the main surface of the base body 152. It has multiple discharge ports and supplies additional mixed gas 133 at the aforementioned upstream position on the base body 152. One embodiment of the nozzle unit 130 will be explained with reference to Figures 3 and 4.

[0039] The nozzle unit 130 can be configured as shown in Figure 3, for example. Figure 3 is a longitudinal cross-sectional view of the nozzle unit 130 as seen from the side. The nozzle unit 130 comprises a plurality of mist supply nozzles 131 and one exhaust nozzle 132. The mist supply nozzle 131 includes an inlet 131a into which the mixed gas 123 is supplied, an outlet 131b for discharging the mixed gas 133, and a supply channel 131c connecting the inlet 131a and the outlet 131b. The exhaust nozzle 132 includes an intake port 132b for recovering the mixed gas 133, an exhaust channel 132c, and an outlet 132a.

[0040] One mist supply nozzle 131 is connected to one of the above-mentioned mist supply systems via piping at its inlet 131a. The exhaust nozzle 132 is connected to the exhaust means 160 via piping at its outlet 132a. Therefore, the mist supply nozzle 131 has the function of discharging a mixture of gases with a flow rate adjusted for each mist supply system to the base 152.

[0041] In the configuration shown in Figure 3, the inlet 131a is located above the supply channel 131c, but the present invention is not limited to this configuration and may be located to the side of the supply channel 131c (perpendicular to the plane of the paper). Furthermore, multiple inlets 131a may be provided for each mist supply nozzle 131 for purposes such as homogenizing the mist concentration distribution within the supply channel 131c.

[0042] The discharge port 131b is positioned along the direction in which the mixed gas 133 flows. Furthermore, it is preferable that the mixed gas 133 is supplied along the film-forming surface of the substrate 152. Therefore, the discharge port 131b is preferably formed at an acute angle or horizontally with respect to the film-forming surface of the substrate 152.

[0043] The shapes of the supply channel 131c and the exhaust channel 132c may be any shape depending on the purpose and application, as long as they do not interfere with the flow paths of other nozzles. In particular, although not shown in the figure, the supply channel 131c may be provided with a stirring structure to homogenize the mist concentration distribution and a structure to adjust the mist droplet size to a desired particle size distribution.

[0044] The air-fuel mixture 133 is discharged from the nozzle unit 130, flows over the substrate 152, and is then recovered from the intake port 132b. During this process, the air-fuel mixture 133 and the substrate 152 react, forming a film on the substrate 152. In Figure 3, the exhaust nozzle 132 is integrally configured with the nozzle unit 130, but the present invention is not limited to this configuration, and the nozzle nozzle may be configured separately from the nozzle unit 130.

[0045] The spacing between adjacent discharge ports 131b is adjusted as appropriate depending on the flow rate of the mixed gas and the physical properties of the raw material mist, but it is generally best to set it to about 5 mm to 30 mm. With spacing within this range, it is possible to achieve efficient results while preventing the nozzle unit structure from becoming overly complex, and to effectively suppress spatial fluctuations in mist concentration.

[0046] Furthermore, the spacing of the discharge ports 131b may be equal from the uppermost part to just before the intake port 132b, or it may vary regularly or irregularly within the preferred installation interval of the discharge ports 131b described above.

[0047] Figure 4 is a view of the nozzle unit 130 facing the base 152 (bottom surface) as seen from the base side. The shape of the opening of the discharge port 131b is not particularly limited and may be rectangular, polygonal, circular, or elliptical, but in the present invention, a slit shape as shown in Figure 4 is preferable. Furthermore, the discharge ports 131b are preferably arranged parallel to the long axis of the slit-shaped opening and spaced apart in the short axis direction.

[0048] This makes it relatively easy to obtain a mist flow with suppressed mist concentration distribution within the gap between the nozzle unit 130 and the substrate 152 (hereinafter also referred to as the "channel"), enabling the easier and more stable production of homogeneous films even on large-area substrates.

[0049] When the discharge port 131b has a slit shape, the opening dimensions can be adjusted as appropriate according to the process conditions, but generally, a length of about 1 mm to 20 mm in the short axis direction is preferable. In the long axis direction, it is preferable to have a sufficient length to match the shape of the substrate, for example, a length of 10% to 30% longer than the width of the corresponding substrate 152 in the long axis direction is preferable.

[0050] The discharge port 131b is located upstream of the base body 152 (far left in Figure 4), and the intake port 132b is located downstream of the base body 152 (far right in Figure 4). This allows the air-mixed gas 133 to flow in one direction from the discharge port 131b to the intake port 132b. Further upstream, multiple discharge ports 131b are arranged on the base body 152 between the discharge port 131b and the intake port 132b, allowing for the supply of additional air-mixed gas 133.

[0051] Furthermore, the distance L between the upstream and downstream ends of the discharge port 131b (also called the discharge port arrangement range) is optimized as appropriate depending on the shape of the substrate 152, but for relatively short substrates such as semiconductor substrates and glass substrates, it is preferable that it be within 30% of the length of the substrate in the same direction (the direction in which the mixed gas 133 flows). By setting the value of L in this way, in addition to the preferred dimensions of the slit's long axis as described above, the mixed gas 133 can be supplied so as to cover the substrate, making it possible to eliminate nozzle sweeping or minimize the sweeping width, thereby suppressing the time loss during film formation and improving productivity.

[0052] The relationship between the major axis dimension of the slit and the value of L can also be described as a rectangle formed by the vertices of the two furthest apart slit-shaped discharge ports 131b, which covers the mounting area [film-forming surface (surface) of the substrate] of the mounting section 151. This will enable the more stable production of homogeneous films.

[0053] The structure and materials of the nozzle unit 130 other than those mentioned above are not particularly limited, and should have sufficient stability depending on the characteristics of the raw materials used and the temperature conditions. In this case, metals such as aluminum and stainless steel may be used, and if film formation is performed at a higher temperature exceeding the heat resistance temperature of these metals, or if acidic or alkaline raw materials are used, alloys such as Hastelloy (registered trademark), soda-lime glass, borosilicate glass, quartz, silicon carbide, carbon, or ceramics such as silicon nitride or aluminum nitride may also be used.

[0054] Furthermore, the nozzle unit 130 may be configured to control the temperature inside the nozzle unit 130 by a temperature control means not shown in the figure. In this case, there is no limit to the control temperature, but it can be, for example, from 10°C to 200°C, and it is particularly good to set it to 20°C to 170°C when using an aqueous raw material solution.

[0055] Furthermore, the shape of the intake port 132b is not particularly limited, but it is preferable to make it rectangular in order to make the flow of the mixture 133 a more uniform laminar flow. In this case, the length of the intake port 132b in the longitudinal direction can be made long enough to match the shape of the base body 152.

[0056] The distance between the intake port 132b and the nearest discharge port 131b is not particularly limited, but if, for example, multiple discharge ports 131b are installed at equal intervals, it is preferable to set the distance to be the same.

[0057] The intake port 132b may be formed such that the direction in which the mixed gas 133 is drawn in forms an angle with respect to the film-forming surface of the substrate 152, or it may be formed horizontally.

[0058] (Exhaust means) The exhaust means 160 exhausts the air-mixed gas 133 supplied to the base 152 from the nozzle unit 130, downstream of the base 152 in the direction of the air-mixed gas 133 flow. In other words, it discharges the air-mixed gas 133 recovered from the exhaust nozzle 132 out of the system.

[0059] The exhaust means 160 is not particularly limited, and known exhaust means can be applied, with general blowers and exhaust fans being preferred. In addition, the exhaust means 160 may include known pollution control devices, particle collectors, or mist traps.

[0060] (Mounting section (stage)) The stage 151 is installed so that the film-forming surface of the substrate 152 and the bottom surface of the nozzle unit 130 are parallel.

[0061] The structure and materials of Stage 151 are not particularly limited, and should have sufficient stability depending on the characteristics of the raw materials used and the temperature conditions. In this case, metals such as aluminum and stainless steel may be used, and if film formation is performed at a higher temperature exceeding the heat resistance temperature of these metals, or if acidic or alkaline raw materials are used, alloys such as Hastelloy®, soda-lime glass, borosilicate glass, quartz, carbon, silicon carbide, or ceramics such as silicon nitride or aluminum nitride may be used.

[0062] The stage 151 may be equipped with a mechanism for holding the substrate 152. In this case, known substrate holding methods such as a vacuum chuck, a mechanical chuck, or an electrostatic chuck can be applied.

[0063] Furthermore, while the film-forming apparatus 100 and 200 of the present invention may perform film formation with the substrate 152 and nozzle unit 130 facing each other and stationary in a predetermined position, it is preferable that the apparatus be equipped with a transport (movement) means (not shown) that can change the relative position in the horizontal direction. By incorporating a means of transport, the thickness distribution of the formed film can be improved.

[0064] In addition, while the configurations in Figures 1 and 2 show the nozzle unit 130 positioned above the stage 151 and the film-forming surface of the substrate 152 facing upwards, the film-forming apparatus 100 and 200 according to the present invention are not limited to this configuration. The nozzle unit 130 may be positioned below the stage 151 and the film-forming surface of the substrate 152 may be facing downwards.

[0065] (Heating means) The film-forming apparatus 100, 200 is equipped with a heating means 170 for heating the substrate 152. The heating means 170 is not particularly limited, but known heating means such as resistance heaters and lamp heaters can be used.

[0066] The heating means 170 may be built into the stage 151 or installed outside the stage 151.

[0067] (Base) The substrate 152 is not particularly limited as long as it can support the film to be formed. The material of the substrate 152 is also not particularly limited as long as it does not hinder the objective of the present invention, and may be a known material, and may be an organic compound or an inorganic compound. Examples include, but are not limited to, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, fluororesin, metals such as iron, aluminum, stainless steel, and gold, silicon, sapphire, quartz, glass, calcium carbonate, lithium tantalate, lithium niobate, gallium oxide, SiC, ZnO, and GaN.

[0068] The shape of the base body 152 can be any of the following: flat plates, discs, fibrous, rod-shaped, cylindrical, prismatic, cylindrical, spiral, spherical, or ring-shaped. In particular, when the base body is plate-shaped, it is not limited in this invention, but the surface area is 5 cm². 2 More preferably 10 cm 2 A substrate having the above characteristics and a thickness of 50 to 2000 μm, more preferably 100 to 800 μm, can be suitably used.

[0069] With the film-forming apparatus 100 and 200 of the present invention described above, regardless of the physical properties of the raw materials used, high-quality films with homogeneous thickness and composition can be stably produced with high productivity, even on large-area substrates.

[0070] [Film forming method] Next, the film-forming method according to the present invention will be described with reference to the figures. Note that the details regarding the film-forming apparatus described above may be omitted.

[0071] The film-forming method according to the present invention can suitably use film-forming apparatuses 100 and 200, and is a film-forming method in which a mixed gas 123 formed by mixing a raw material mist 122 obtained by atomizing a raw material solution 121 with a carrier gas is supplied from upstream of the substrate 152 so as to flow in one direction along the main surface of the substrate 152, and exhausted downstream of the substrate 152 in the one direction, thereby forming a film on the substrate 152 by thermal reaction, wherein an additional mixed gas 133 is supplied at the position on the substrate 152 in the one direction upstream.

[0072] The carrier gas is not particularly limited; for example, air, oxygen, ozone, inert gases such as nitrogen and argon, or reducing gases such as hydrogen gas and foaming gas are preferably used. There may be one type of carrier gas or two or more types.

[0073] The carrier gas flow rate can be set appropriately depending on the size of the substrate 152 and the process conditions, and can be set to, for example, about 0.01 to 100 L / min.

[0074] Although not shown in the diagram, it is also possible to adjust the ratio of raw material mist 122 to carrier gas by adding a diluent gas. In this case, the flow rate of the diluent gas can be set as appropriate, for example, to 0.1 to 10 times the carrier gas flow rate per minute. The diluent gas may be supplied, for example, to the downstream side of the atomizer 120. The diluent gas may be the same as the carrier gas, or a different one may be used.

[0075] The atomizing device 120 contains a raw material solution 121 as the raw material. The raw material solution 121 is not particularly limited as long as it is an atomizable solution, and organic solvent solutions or aqueous solutions such as alcohols or ketones containing raw materials according to the purpose can be used.

[0076] The raw material solutions 121 filled into multiple atomizing devices 120 should ideally use the same raw materials. That is, the main components and their proportions in the raw material solutions 121 should be similar. Here, the main components refer to components that make up 50% or more of the solid content excluding the solvent.

[0077] The raw material solution 121 is atomized using known means to form a raw material mist 122. The method for atomizing the raw material solution 121 is not particularly limited as long as it can atomize or droplet the raw material solution 121, and may be a known means, but in the present invention, the use of ultrasound is preferred.

[0078] Mist or droplets obtained using ultrasound are preferable because they have zero initial velocity and float in the air. For example, they are highly preferable because they can be transported as a gas while floating in space, rather than being sprayed like a spray, thus avoiding damage from collision energy.

[0079] The droplet size is not particularly limited and may be several millimeters in size, but is preferably 50 μm or less, and more preferably 0.1 to 10 μm.

[0080] The atomization rate of the atomizing device 120 may be the same for all atomizing devices 120, or it may differ. In the latter case, for example, the number of ultrasonic transducers used for ultrasonic atomization can be changed, or transducers with different outputs can be applied to different atomizing devices 120. Note that as the atomization rate increases, the mist concentration in the mixed gas becomes relatively higher.

[0081] Film formation may be carried out under atmospheric pressure, pressurized pressure, or reduced pressure, but it is preferable to carry it out under atmospheric pressure in terms of equipment cost and productivity.

[0082] The mist concentration of the mixed gas 133 discharged from a single mist supply nozzle 131 to the base 152 decreases by reaction with the base 152 and evaporation as it reaches the intake port 132b. However, the mixed gas 133 is discharged in multiple stages from multiple mist supply nozzles 131 located along the way to compensate for this decrease. In other words, additional mixed gas 133 can be supplied at multiple locations along the flow direction of the mixed gas 133.

[0083] Therefore, the decrease in mist concentration in the channel is suppressed, making it possible to maintain a high mist concentration within the channel. As a result, a consistent film deposition rate can be obtained throughout the entire channel.

[0084] Furthermore, when film formation is performed by mixing raw material mist 122 generated from multiple different raw material solutions 121, changes in the composition of the mixture 133 due to differences in physical properties such as evaporation rate depending on the raw material are suppressed, so that a film with a uniform composition can be formed on the substrate surface.

[0085] In this case, the additional supply can be controlled by controlling the supply amount for each type of raw material mist contained in the mixture 123. This makes it easier to produce homogeneous films even when using raw material solutions with different physical properties simultaneously.

[0086] Furthermore, the mist concentration distribution within the channel can be understood, for example, as the film thickness distribution of the film formed on the substrate. In this case, the film thickness distribution can be evaluated by fixing the positions of the nozzle unit 130 and the substrate 152 facing each other, performing film formation, and measuring the film thickness distribution in the direction of the gas flow.

[0087] Film thickness can be measured using known film thickness measurement methods, with polarization analysis, spectral reflectance analysis, stylus method, and laser displacement meter being preferred. In addition, it is possible to measure the mist concentration distribution from the transmittance and amount of light scattering of light irradiated into the mixture in the channel.

[0088] The method for measuring the membrane composition distribution is not particularly limited, and a wide range of known evaluation methods can be applied. For example, X-ray fluorescence spectroscopy and secondary ion mass spectrometry are preferably used.

[0089] The flow rate of the mixed gas 123 in each mist supply system is adjusted as appropriate in conjunction with the specifications of the nozzle unit 130 and the process conditions. For example, when an aqueous solution is used as the raw material, if the flow rate of the mixed gas supplied to the uppermost mist supply nozzle 131 (the leftmost part of the page in Figure 3) in the mixed gas flow on the base 152 is set to 1, then the flow rates supplied to the nozzles other than that nozzle should be set to approximately 0.01 to 0.35.

[0090] The exhaust volume of the exhaust means 160 may be adjusted as appropriate depending on the film formation conditions, but in order to avoid the generation of turbulence in the mixture 133, it is preferable to set it to about 70-150% of the flow rate of the mixture 133, and more preferably to about 80-130%.

[0091] In film formation, the nozzle unit 130 may be moved, or the stage 151 may be moved, but it is preferable to move the stage 151. The movement may be a reciprocating motion in a horizontal uniaxial direction, or it may be a horizontal rotational motion, but in the present invention, horizontal movement is preferred.

[0092] The travel distance at this time is adjusted as appropriate according to the film formation process conditions, but it is preferable to make it approximately the same as the distance between the discharge ports 132b. This allows for the formation of a more homogeneous membrane while maintaining a high growth rate.

[0093] The transfer speed at this time may be adjusted as appropriate according to the film formation process conditions, but it is preferable to keep it below 100 mm / second. Below 100 mm / second, the relative speed with respect to the mixed airflow velocity becomes a more effective speed for film formation, and the film thickness distribution can be improved more efficiently. There is no particular lower limit, but it can generally be set to around 1 mm / second.

[0094] With the film-forming method according to the present invention described above, regardless of the physical properties of the raw materials used, high-quality films with homogeneous thickness and composition can be stably produced with high productivity, even on large-area substrates. [Examples]

[0095] The present invention will be described in detail below with reference to examples, but this is not intended to limit the present invention.

[0096] (Example 1) α-Ga2O3 films were deposited using a film deposition apparatus as shown in Figure 1, with nozzle units as shown in Figures 3 and 4.

[0097] The nozzle unit was made of graphite coated with silicon carbide, and had 12 discharge ports with an opening size of 2 mm x 130 mm spaced 10 mm apart (L=132 mm). In addition, an intake port with an opening size of 4 mm x 130 mm was located 10 mm downstream from the furthest discharge port.

[0098] A SiC hot plate with a built-in resistance heating element was used as the stage.

[0099] A gas cylinder filled with nitrogen gas was used as the carrier gas supply. The gas cylinder and the atomizer were connected with a urethane resin tube, and the atomizer and the nozzle unit were further connected with a quartz pipe.

[0100] As the raw material solution, a dilute hydrochloric acid aqueous solution was prepared by adding 1% by volume of 34% hydrochloric acid, dissolving gallium acetylacetonate at a concentration of 0.15 mol / L, and stirring with a stirrer for 60 minutes. This solution was then filled into the atomizer. The atomizer used was equipped with two ultrasonic vibrating plates (frequency 2.4 MHz).

[0101] Next, ultrasonic vibrations (frequency 2.4 MHz) were transmitted through water using an ultrasonic vibrating plate to the raw material solution inside the atomizing device, thereby atomizing (misting) the raw material solution.

[0102] Next, a c-plane sapphire substrate with a thickness of 0.6 mm and a diameter of 4 inches (approximately 10 cm) was placed on the stage and heated to a substrate temperature of 450°C.

[0103] Next, the stage was moved to position the circuit board directly below the center of the nozzle unit, and then it was repeatedly moved back and forth horizontally at a speed of 5 mm per second and a distance of 10 mm.

[0104] Next, nitrogen gas was added to each atomizer to supply a mixture of mist and nitrogen gas to the nozzle unit. At this time, the flow rate to the uppermost discharge nozzle was set to 13 L / min, and the flow rate to the other nozzles was set to 1.3 L / min (total 27.3 L / min). Exhaust was also performed with an exhaust flow rate of 28 L / min.

[0105] Under the above conditions, film formation was performed for 20 minutes, and immediately afterward, the supply of nitrogen gas was stopped, thereby halting the supply of the mixed gas to the nozzle unit.

[0106] The fabricated film was confirmed to be α-Ga2O3 based on the appearance of a peak around 2θ = 40.3° in X-ray diffraction measurements.

[0107] Subsequently, the film thickness was measured at nine points starting 5 mm inward from the outer edge of the substrate using optical reflectance analysis (Filmetrics F50). The average film thickness was calculated from these measurements, and the film formation (growth) rate was calculated by dividing the average film thickness by the above-mentioned film formation time. In addition, the film thickness distribution was calculated by dividing the difference between the maximum and minimum film thicknesses on the substrate surface by twice the average film thickness.

[0108] (Comparative Example 1) A film-forming apparatus equipped with a nozzle unit having one discharge port was used, and film formation was carried out under the same conditions as in Example 1, except that the mixed air flow rate to the discharge port was set to 27.3 L / min and the travel distance was set to 120 mm.

[0109] The fabricated film was confirmed to be α-Ga2O3 based on the appearance of a peak around 2θ = 40.3° in X-ray diffraction measurements. After this, the film was evaluated in the same manner as in Example 1.

[0110] Table 1 shows the evaluation results (growth rate, film thickness distribution) for Example 1 and Comparative Example 1.

[0111] [Table 1]

[0112] In both Example 1 and Comparative Example 1, the formed film was α-gallium oxide. However, as shown in Table 1, the results for Example 1 showed improved film growth rate and film thickness distribution compared to Comparative Example 1.

[0113] (Example 2) In the film deposition apparatus configuration shown in Figure 2, a Ga-Al-O based oxide film was deposited using a film deposition apparatus equipped with 12 mist supply systems and a nozzle unit similar to that used in Example 1.

[0114] A SiC hot plate with a built-in resistance heating element was used as the stage.

[0115] A gas cylinder filled with nitrogen gas was used as the carrier gas supply. The gas cylinder and the atomizer were connected with a urethane resin tube, and the atomizer and the nozzle unit were further connected with a quartz pipe.

[0116] As a raw material solution, a dilute hydrochloric acid aqueous solution was prepared by adding 1% by volume of 34% hydrochloric acid, dissolving gallium acetylacetonate at a concentration of 0.1 mol / L, stirring with a stirrer for 60 minutes, and then filling the atomizer 120A with this solution.

[0117] In addition, a dilute hydrochloric acid aqueous solution was prepared by adding 1% by volume of 34% hydrochloric acid, dissolving aluminum acetylacetonate at a concentration of 0.1 mol / L, stirring with a stirrer for 60 minutes, and this solution was then filled into the atomizer 120B.

[0118] The atomizing device used was equipped with two ultrasonic vibrating plates (frequency 2.4 MHz).

[0119] Next, ultrasonic vibrations were transmitted through water to the raw material solution inside the atomizing device using an ultrasonic vibrating plate, thereby atomizing (misting) the raw material solution.

[0120] Next, a quartz substrate measuring 0.6 mm thick and 10 cm square was placed on the stage and heated to a temperature of 450°C.

[0121] Next, the stage was moved and the circuit board was positioned directly below the center of the nozzle unit.

[0122] Next, nitrogen gas was supplied to atomizers 120A and 120B at a flow rate of 10:3, and a mixture of mist and nitrogen gas was supplied to the nozzle unit.

[0123] At this time, the total flow rate to the uppermost discharge nozzle was set to 13 L / min, and the total flow rate to the other nozzles was set to 1.3 L / min (total flow rate of 27.3 L / min). Exhaust was also performed with an exhaust flow rate of 28 L / min.

[0124] Under the above conditions, film formation was performed for 20 minutes, and immediately afterward, the supply of nitrogen gas was stopped, thereby halting the supply of the mixed gas to the nozzle unit.

[0125] Next, elemental analysis of the fabricated films was performed using an energy-dispersive X-ray fluorescence spectrometer (JEOL JSM-6510, accelerating voltage 5kV) at five points on the centerline of the substrate, parallel to the flow direction of the mixed gas, starting 5 mm inward from the outer edge of the substrate.

[0126] The obtained characteristic X-ray spectra showed signals for O, Ga, and Al at all measurement points, confirming that the fabricated film is a Ga-Al-O oxide.

[0127] Subsequently, the aluminum / gallium composition ratio ([Al] / [Ga]) was measured from the peak intensity ratio of characteristic X-rays of aluminum (Kα line: 1.486 keV) and characteristic X-rays of gallium (Lα line: 1.098 keV).

[0128] (Comparative Example 2) In the film-forming apparatus of Example 2, a device equipped with a nozzle unit having one discharge port was used, and the mixed air flow rate to the discharge port was set to 27.3 L / min. Film formation was performed under the same conditions as in Example 2, except that horizontal reciprocating movement over a distance of 120 mm was repeated at a speed of 5 mm per second.

[0129] Next, elemental analysis of the fabricated film was performed in the same manner as in Example 2. The obtained characteristic X-ray spectra showed signals for O, Ga, and Al at all measurement points, confirming that the fabricated film is a Ga-Al-O oxide. After this, the film was evaluated in the same manner as in Example 2.

[0130] Figure 5 shows the evaluation results for Example 2 and Comparative Example 2. The origin in the figure is the upstream side of the mixed gas supply. In both cases, the formed film was a Ga-Al-O oxide, but the [Al] / [Ga] distribution was very non-uniform in Comparative Example 2, whereas it was uniform in-plane in Example 2.

[0131] As described above, according to the embodiments of the present invention, it was possible to manufacture homogeneous and high-quality films on large-area substrates with higher productivity compared to using the prior art.

[0132] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. [Explanation of Symbols]

[0133] 100, 200... Film-forming apparatus, 111... Carrier gas supply means, 112...Carrier gas piping, 120, 120A, 120B...Atomizing means (atomizing device), 121... Raw material solution, 122... Raw material mist, 123, 123a, 123b, 133... Mixture, 124... Mist piping, 130...Nozzle unit, 131...Mist supply nozzle, 131a...Inlet 131b...Discharge port, 131c...Supply channel, 132...Exhaust nozzle, 132a... Exhaust port, 132b... Intake port, 132c... Exhaust passage, 140...Flow rate adjustment unit, 151...Mounting unit (stage), 152...Base unit, 160... Exhaust means, 170... Heating means, L…The distance between the upstream and downstream ends of the discharge port.

Claims

1. A film-forming method is provided in which a mixture formed by mixing a raw material mist obtained by atomizing a raw material solution with a carrier gas is supplied from the upstream side of the substrate so as to flow in one direction along the main surface of the substrate, and exhausted downstream of the substrate in the same direction, thereby forming a film on the substrate by a thermal reaction, A film-forming method characterized by supplying the mixed gas at the aforementioned position on the substrate.

2. The film-forming method according to claim 1, characterized in that the additional supply is performed by controlling the supply amount for each type of raw material mist contained in the mixture.

3. The film-forming method according to claim 1 or 2, characterized in that the additional supply is performed at multiple positions on the one-sided improvement.

4. A atomizing means for atomizing a raw material solution to generate a raw material mist, A carrier gas supply means for supplying a carrier gas for transporting the aforementioned raw material mist, A flow rate adjustment unit that adjusts the flow rate of the carrier gas, or the mixture of the raw material mist and the carrier gas, A nozzle unit having multiple discharge ports for supplying the aforementioned mixture, A mounting section on which the base is placed, A heating means for heating the substrate, Exhaust means for exhausting the mixture supplied from the nozzle unit to the substrate, A film-forming apparatus comprising, The nozzle unit supplies the mixture from the upstream of the substrate so that it flows in one direction along the main surface of the substrate, and the exhaust means exhausts the mixture downstream of the substrate in the one direction. The film-forming apparatus is characterized in that the nozzle unit supplies the mixed gas at a position on the base that is raised on one side.

5. The film-forming apparatus according to claim 4, characterized in that the plurality of discharge ports have a slit shape at the opening portion and are arranged parallel to the long axis direction of the opening portion and spaced apart in the short axis direction.

6. The film-forming apparatus according to claim 5, characterized in that a rectangle formed by the vertices of both ends of the two slit-shaped discharge ports located furthest apart is configured to cover the mounting area of ​​the base of the mounting part described above.

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