Film forming apparatus and method of using the same

Abstract

To suppress deterioration in film quality in a mist CVD method.SOLUTION: A film formation device 10 comprises: a stage 12 onto which a substrate 2 is mounted; a heater 14 that heats the substrate on the stage; a mist generation source 20 that generates mist of a solution 6 in which a material constituting a film 4 is solved and at least water is contained; a supply path 30 that transfers the mist generated in the mist generation source to the substrate on the stage by a flow of a transfer gas; and a heater 34 that heats at least one part of the supply path. A section of the supply path heated by the heater becomes a mist heating section HS to which each infrared radiation (R1 and R2) is radiated toward the mist from an inner surface of the supply path. In the mist heating section, the inner surface of the supply path is coated with a coated layer 40 containing at least one of an oxide or a hydroxide of an element existing in the mist.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to a film forming apparatus and a method of using the same.

[0002] Patent Document 1 discloses a film forming apparatus. This film forming apparatus is configured to form a film on the surface of a substrate by the mist CVD method, and includes a supply path through which mist generated by a mist generation source is conveyed by the flow of a carrier gas, and a heater that heats at least a part of the supply path.

[0003] By heating the supply path as in the above-described manufacturing method, condensation and aggregation of mist in the supply path can be prevented. By preventing condensation and aggregation of mist, the supply amount of mist supplied to the substrate can be increased, and the film forming rate can be improved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, even if the supply path is heated, condensation and aggregation of mist in the supply path cannot be completely prevented. As a result, when the use of the film forming apparatus is repeated, deposits derived from condensation and aggregation of mist adhere to the inner surface of the supply path. And it has been found that as the adhesion of the deposits progresses, the quality of the film formed on the substrate (hereinafter referred to as film quality) deteriorates. This specification provides a technology capable of suppressing such deterioration of film quality.

Means for Solving the Problems

[0006] When the supply path is heated, the mist conveyed inside the supply path is also heated, and the heated mist is supplied to the substrate. However, as the use of the film forming apparatus is repeated and deposits adhere to the inner surface of the supply path, the amount of heat (especially the dose of infrared rays) transferred from the inner surface of the supply path to the mist decreases. As a result, the temperature rise in the mist becomes smaller, and the temperature of the mist supplied to the substrate unintentionally decreases, leading to deterioration of the film quality. Therefore, if it is possible to suppress the decrease in the amount of heat (especially the dose of infrared rays) transferred from the inner surface of the supply path to the mist during the process of repeated use of the film forming apparatus, it is possible to suppress the deterioration of the film quality. And for that purpose, it is conceivable to previously coat the inner surface of the supply path with a material equivalent or approximate to the deposits derived from the mist.

[0007] Based on the above findings, a film forming apparatus (10, 110, 210, 310) for forming a film (4) on the surface of a substrate (2) is disclosed. This film forming apparatus includes a stage (12) on which the substrate is placed, a mist generation source (20) that generates a mist (7) of a solution (6) in which a material constituting the film is dissolved and that contains at least water, a supply path (30) that conveys the mist generated by the mist generation source to the substrate on the stage by the flow of a carrier gas, and a heater (34) that heats at least a part of the supply path. The section of the supply path heated by the heater becomes a mist heating section (HS) where infrared rays (R1, R2) are irradiated from the inner surface (30a) of the supply path toward the mist. In the mist heating section, the inner surface of the supply path is covered with a coating layer (40) containing at least one of an oxide or a hydroxide of an element present in the mist.

[0008] In the above-described film-forming apparatus, the heater heats the supply path, thereby forming a mist heating section in the supply path. In the mist heating section, infrared rays are irradiated from the inner surface of the supply path toward the mist. The inner surface of the mist heating section is pre-coated with a material equivalent to or approximating the deposits derived from the mist. As a result, in the process of repeatedly using the film-forming apparatus, even if deposits derived from the mist further adhere, the reduction in the amount of heat (particularly, the amount of infrared rays) transmitted from the inner surface of the supply path to the mist is small. As a result, the temperature drop of the mist supplied to the substrate is also suppressed, and film formation under predetermined optimal conditions can be continued over a long period of time.

[0009] In one embodiment of the present technology, the coating layer may be composed of only the elements contained in the mist. According to such a configuration, it is possible to avoid the film formed by the film-forming apparatus from containing impurities.

[0010] In one embodiment of the present technology, the supply path may include a film-forming chamber (12) in which a stage is disposed. In this case, when the temperature of the substrate during film formation is T1 and the temperature T2 of the inner surface of the film-forming chamber facing the surface of the substrate, T1 > T2 may be satisfied. That is, it may be a so-called cold wall method. In the cold wall method, since the mist is not heated in the film-forming chamber, the temperature rise of the mist in the mist heating section greatly affects the final temperature of the mist supplied to the substrate and can also have a great influence on the film quality. In other words, in the cold wall method, the film quality can be effectively stabilized by stabilizing the temperature rise of the mist in the mist heating section, and therefore, the present technology can be preferably adopted.

[0011] In one embodiment of the present technology, the coating layer in the mist heating section may have an absorption rate of 50% or more with respect to the infrared rays irradiated from the inner surface of the supply path toward the mist. According to such a configuration, in the process of repeatedly using the film-forming apparatus, even when deposits derived from the mist further adhere, the reduction in the amount of infrared rays irradiated to the mist is effectively suppressed.

[0012] In one embodiment of the present technology, the film formed on the surface of the substrate may be an epitaxial film. However, as another embodiment, the film formed on the surface of the substrate may not be an epitaxial film, and may be a film having a crystal structure or a film having no crystal structure.

[0013] In one embodiment of the present technology, the inner surface of the supply path in the mist heating section may be made of quartz. In this case, the quartz may contain a hydroxyl group (OH group). Quartz is a chemically stable substance and also has excellent heat resistance. Therefore, quartz can be adopted as the material constituting the supply path. On the other hand, since quartz also has a high transmittance in the infrared region where it is easily absorbed by water, when deposits due to condensation and aggregation of mist adhere, the amount of infrared rays irradiated to the mist will change significantly. In order to suppress such a change, it is advisable to form a coating layer on the inner surface of the supply path in advance. In this regard, the effect of the present technology is significantly exerted.

[0014] In one embodiment of the present technology, when the temperature of the heater is T3, T3≥100°C may be satisfied. In order to suppress the condensation and aggregation of the mist of the solution containing water, it is advisable to set the temperature of the heater to 100°C or higher. However, when the temperature of the heater is set to 100°C or higher, due to the evaporation of the water contained in the mist, deposits are likely to adhere to the inner surface of the supply path, leading to a change in the amount of infrared rays irradiated to the mist. In order to suppress such a change, it is advisable to form a coating layer on the inner surface of the supply path in advance. In this regard, the effect of the present technology is significantly exerted.

[0015] In one embodiment of the present technology, the supply path may include a film deposition chamber in which the stage is disposed. In this case, when the temperature of the inner surface of the film deposition chamber is T2 and the temperature of the heater is T3, the relationship T2 < T3 may be satisfied. According to such a configuration, the mist is not heated so much in the film deposition chamber. Therefore, the temperature rise of the mist in the mist heating section greatly affects the final temperature of the mist supplied to the substrate and can also have a great influence on the film quality. In other words, when the above-described relationship T2 < T3 is satisfied, the film quality can be effectively stabilized by stabilizing the temperature rise of the mist in the mist heating section. Therefore, the present technology can be preferably adopted.

[0016] In one embodiment of the present technology, the wavelength λ of the infrared rays irradiated on the mist may be λ ≤ 7.8 micrometers. In film deposition using a mist of a solution containing water, a film is formed on the surface of the substrate by removing at least a part of the water. Therefore, usually, the heater preferably has a temperature of 100°C or higher, and from such a heater, a large amount of infrared rays having a wavelength of 7.8 micrometers or less is radiated based on Wien's displacement law. The wavelength of 7.8 micrometers or less is a wavelength band that is easily absorbed by water and greatly affects the temperature rise of the mist containing water. Therefore, in order to stabilize the film quality, it is particularly effective to suppress the change in the amount of infrared rays irradiated on the mist. Therefore, the present technology can be preferably adopted.

[0017] The present technology is also embodied in a method of using a film forming apparatus. The film forming apparatus is an apparatus for forming a film on the surface of a substrate, and includes a stage on which the substrate is placed, a heater for heating the substrate on the stage, a mist generation source that dissolves a material constituting the film and generates a mist of a solution containing at least water, a supply path for transporting the mist generated at the mist generation source to the substrate on the stage by the flow of a carrier gas, and a heater for heating at least a part of the supply path. In this film forming apparatus, a section of the supply path heated by the heater becomes a mist heating section where infrared rays are irradiated from the inner surface of the supply path toward the mist. The method of use has a preliminary step and a film forming step carried out after the preliminary step. In the preliminary step, while operating the heater, the mist generated at the mist generation source is supplied to the mist heating section to form a coating layer on the inner surface of the mist heating section. In the film forming step, while operating the heater, the mist generated at the mist generation source is supplied to the substrate on the stage through the supply path to form a film on the surface of the substrate.

[0018] In the above-described method of use, by carrying out the preliminary step, the inner surface of the mist heating section can be pre-coated with a material corresponding to or approximating the deposits derived from the mist. Thereby, in the subsequent film forming step, it is possible to effectively suppress the decrease in the amount of heat (particularly, the amount of infrared rays) transmitted from the inner surface of the supply path to the mist. As a result, the temperature of the mist supplied to the substrate does not unintentionally decrease, and film formation under predetermined optimal conditions can be continued over a long period.

[0019] In one embodiment of the present technology, when the temperature of the inner surface of the mist heating section in the preliminary step is T4 and the temperature of the heater in the film forming step is T3, the relationship T3 < T4 may be satisfied. According to such a configuration, in the preliminary step, since the inner surface of the mist heating section becomes relatively high in temperature, the formation of the coating layer is effectively promoted.

[0020] In one embodiment of the present technology, when the temperature of the inner surface of the mist heating section in the preliminary process is T4 and the temperature of the substrate in the film formation process is T1, the relationship T1 < T4 may be satisfied. According to such a configuration, in the preliminary process, since the inner surface of the mist heating section becomes relatively high in temperature, the formation of the coating layer is effectively promoted.

[0021] In one embodiment of the present technology, the mist in the preliminary process may be the same as the mist in the film formation process. In this case, although not particularly limited, the preliminary process and the film formation process may be continuously performed. However, as another embodiment, the mist in the preliminary process may be different from the mist in the film formation process.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0023] (Example 1) With reference to the drawings, the film-forming apparatus 10 of Example 1 will be described. As shown in Fig. 1, the film-forming apparatus 10 of the present embodiment forms a film 4 on the surface of a substrate 2 using the mist CVD method. Although not particularly limited, the substrate 2 may be a gallium oxide substrate, and the film 4 may be a homoepitaxial growth film of gallium oxide.

[0024] The film-forming apparatus 10 includes a film-forming chamber 12 in which the substrate 2 is disposed, a mist generation source 20 that generates a mist 7, and a mist supply path 30 that connects the mist generation source 20 and the film-forming chamber 12 to each other. The film-forming chamber 12 has a stage 14 on which the substrate 2 is placed and a stage heater 16 that heats the substrate 2 on the stage 14. When the temperature of the substrate 2 during film formation is T1 and the temperature T2 of the inner surface of the film-forming chamber 12 facing the surface of the substrate 2, T1 > T2 is satisfied. Note that the specific configuration of the film-forming chamber 12 is not particularly limited.

[0025] The mist generation source 20 has a raw material solution tank 22, a water tank 24, and an ultrasonic vibrator 26. The raw material solution tank 22 is a container that stores the raw material solution 6. The raw material solution 6 is a solution in which the material constituting the film 4 is dissolved and is a solution containing at least water. The raw material solution tank 22 is connected to the film-forming chamber 12 via the mist supply path 30. The water tank 24 is a container that stores water. The upper part of the water tank 24 is open, and the raw material solution tank 22 is received from the open upper part. The bottom surface of the raw material solution tank 22 is immersed in the water in the water tank 24.

[0026] The ultrasonic vibrator 26 is a device that generates ultrasonic vibrations. The ultrasonic vibrator 26 is disposed at the bottom of the water tank 24 and faces the bottom surface of the raw material solution tank 22. The ultrasonic vibrations generated by the ultrasonic vibrator 26 are transmitted to the raw material solution 6 in the raw material solution tank 22 through the water in the water tank 24. When ultrasonic vibrations are transmitted to the raw material solution 6, the surface of the raw material solution 6 vibrates, thereby generating mist 7 of the raw material solution 6 in the raw material solution tank 22. Although not particularly limited, the bottom surface of the raw material solution tank 22 is preferably a film made of a flexible material, whereby ultrasonic vibrations are more easily transmitted to the raw material solution 6.

[0027] A supply path 28 for a carrier gas is connected to the raw material solution tank 22. The carrier gas supply path 32 supplies a carrier gas such as nitrogen gas (N2) into the raw material solution tank 22. Thereby, the mist 7 generated in the raw material solution tank 22 flows into the mist supply path 30 by the flow of the nitrogen gas (N2) and is supplied into the film formation chamber 12 through the mist supply path 30. A supply path 32 for a dilution gas is connected to the mist supply path 30. The dilution gas supply path 32 supplies a dilution gas such as nitrogen gas (N2) into the mist supply path 30. The mist 7 is supplied into the film formation chamber 12 at an appropriate density and flow rate by these carrier gases and dilution gases.

[0028] The mist supply path 30 is a tubular member that communicates with each other between the raw material solution tank 22 and the film formation chamber 12. Although not particularly limited, the mist supply path 30 in this embodiment is made of quartz. Note that this quartz may be anhydrous quartz that substantially does not contain a hydroxyl group (OH group), or quartz that contains a relatively large amount of hydroxyl groups. A heater 34 is provided in the mist supply path 30. The heater 34 is provided along the mist supply path 30 and heats at least a part of the section HS of the mist supply path 30. The specific configuration of the heater 34 is not particularly limited. By heating the mist supply path 30, the heater 34 suppresses the condensation and aggregation of the mist 7 passing through the mist supply path 30. The temperature T3 of the heater 34 may be, for example, T3 ≥ 100°C.

[0029] As shown in FIG. 2, a part of the infrared rays R1 generated by the heater 34 passes through the mist supply path 30 and irradiates the mist 7. The wavelength λ of the infrared rays R1 changes according to the temperature T3 of the heater 34 (see Planck's law). For example, when T3 = 400 ° C, the infrared rays R1 have a wavelength of λ = about 2.5 to 15.2 micrometers and have a peak of amplitude at λ = 5.1 micrometers. In addition, the mist supply path 30 heated by the heater 34 also generates infrared rays R2, and a part of the infrared rays R2 irradiates the mist 7. Thus, in the section HS of the mist supply path 30 heated by the heater 34, the infrared rays R1 and R2 are irradiated from the inner surface 30a of the mist supply path 30 toward the mist 7, so that the mist 7 passing therethrough is also heated. Therefore, the section HS heated by the heater 34 is hereinafter referred to as the mist heating section HS.

[0030] When the use of the film forming apparatus 10 is repeated, deposits derived from the condensation and aggregation of the mist 7 adhere to the inner surface 30a of the mist supply path 30. The deposits adhering to the inner surface 30a absorb the infrared rays R1 and R2 irradiated from the inner surface 30a of the mist supply path 30 to the mist 7. Therefore, as the adhesion of the deposits progresses, the amount of heat (dose of the infrared rays R1 and R2) transmitted to the mist 7 decreases, and the temperature rise generated in the mist 7 also becomes smaller. As a result, the temperature of the mist 7 supplied to the substrate 2 unintentionally decreases, leading to deterioration of the film quality. In other words, in the process of repeating the use of the film forming apparatus 10, if it is possible to suppress the decrease in the amount of heat (dose of the infrared rays R1 and R2) transmitted from the inner surface 30a of the mist supply path 30 to the mist 7, it is possible to suppress the deterioration of the film quality. And for that purpose, it is conceivable to previously coat the inner surface 30a of the mist supply path 30 with a material equivalent or approximate to the deposits derived from the mist 7.

[0031] Based on the above findings, in the mist heating section HS in this embodiment, the inner surface 30a of the mist supply path 30 is covered with a coating layer 40. The material constituting the coating layer 40 contains at least one of oxides or hydroxides of elements present in the mist 7. Since the mist supply path 30 is made of transparent quartz, the formation of the coating layer 40 on its inner surface 30a gives the mist supply path 30 an appearance similar to that of frosted glass. The pre-formation of the coating layer 40 on the inner surface 30a of the mist supply path 30 reduces the decrease in the amount of heat (the dose of infrared rays R1, R2) transmitted from the inner surface 30a of the mist supply path 30 to the mist 7, even if deposits derived from the mist 7 adhere further. As a result, the temperature drop of the mist 7 supplied to the substrate 2 is also suppressed, and film formation under predetermined optimal conditions can be continued over a long period.

[0032] Specific configurations of the coating layer 40, such as indicators like thickness and density, are not particularly limited. However, the coating layer 40 may have an absorption rate of 50 percent or more with respect to the infrared rays R1, R2 irradiated from the inner surface 30a of the mist supply path 30 toward the mist 7. According to such a configuration, even when deposits caused by the mist 7 adhere further during the process of repeated use of the film forming apparatus 10, the decrease in the infrared ray dose irradiated to the mist 7 is effectively suppressed.

[0033] In the film forming apparatus 10 of this embodiment, when the temperature of the heater 34 is T3, T3 ≥ 100°C may be satisfied. In this case, when the temperature of the inner surface of the film forming chamber 12 is T2, the relationship T2 < T3 may be satisfied. According to such a configuration, the mist 7 is mainly heated in the mist heating section HS and is not heated much in the film forming chamber 12. Therefore, the temperature rise of the mist 7 in the mist heating section HS greatly affects the final temperature of the mist 7 supplied to the substrate 2 and can also have a great impact on the film quality. Therefore, when the above-described relationship T2 < T3 is satisfied, the film quality can be effectively stabilized by stabilizing the temperature rise of the mist 7 in the mist heating section HS. For this purpose, as described in this embodiment, the inner surface 30a of the mist supply path 30 may be pre-covered with the coating layer 40.

[0034] When the temperature T3 of the heater 34 satisfies T3 ≥ 100°C, based on Wien's displacement law, a large amount of infrared rays R1 and R2 having wavelengths of 7.8 micrometers or less are radiated from the heater 34. The wavelengths of 7.8 micrometers or less are wavelength bands that are easily absorbed by water and greatly affect the temperature rise of the mist 7 containing water. Therefore, in order to stabilize the film quality, it is particularly effective to suppress changes in the amount of infrared rays irradiated to the mist 7. For this purpose, the inner surface 30a of the mist supply path 30 may be covered with the coating layer 40 in advance.

[0035] Next, with reference to FIGS. 3 and 4, a method of using the film forming apparatus 10 will be described. This method of use has a preliminary step and a film forming step carried out after the preliminary step. As shown in FIG. 3, in the preliminary step, while operating the heater 34, the mist 7 generated by the mist generation source 20 is supplied to the mist supply path 30. Thereby, the coating layer 40 is formed on the inner surface 30a of the mist supply path 30, particularly on the inner surface 30a located in the mist heating section HS. In addition, at the stage before carrying out the preliminary step, the coating layer 40 may or may not be formed in advance on the inner surface 30a of the mist supply path 30. That is, the coating layer 40 may be formed for the first time by the preliminary step. In this case, the coating layer 40 can be composed only of the elements contained in the mist 7.

[0036] In the preliminary step, it is preferable that the mist 7 in the mist supply path 30 is exhausted to the outside without being supplied to the film forming chamber 12. Therefore, an exhaust path 38 may be provided in the mist supply path 30 via a branch valve 36. The branch valve 36 is located on the downstream side of the mist heating section HS and is configured to selectively guide the mist 7 that has passed through the mist heating section HS to one of the film forming chamber 12 and the exhaust path 38.

[0037] Thereafter, as shown in FIG. 4, in the film formation step, while operating the heater 34, the mist 7 generated by the mist generation source 20 is supplied to the film formation chamber 12 through the mist supply path 30. In the film formation chamber 12, the substrate 2 is placed on the stage 14, and the substrate 2 on the stage 14 is heated to the temperature T1 by the stage heater 16. The mist 7 supplied to the film formation chamber 12 is supplied to the substrate 2 on the stage 14, thereby forming a film 4 on the surface of the substrate 2. Since the coating layer 40 is previously formed on the inner surface 30a of the mist supply path 30, in the film formation step, film formation can be carried out with a stable film quality.

[0038] Although not particularly limited, the relationship T1 < T4 may be satisfied between the temperature T4 of the heater 34 in the preliminary step and the temperature T1 of the substrate 2 in the film formation step. According to such a configuration, in the preliminary step, since the inner surface 30a of the mist heating section HS becomes relatively high temperature, the formation of the coating layer 40 is effectively promoted. Note that, in the preliminary step, the temperature of the inner surface 30a of the mist heating section HS is substantially equal to the temperature T4 of the heater 34. Also, the relationship T3 < T4 is preferably satisfied between the temperature T4 of the heater 34 in the preliminary step and the temperature T3 of the heater 34 in the film formation step. Even in this case, in the preliminary step, since the inner surface 30a of the mist heating section HS becomes relatively high temperature, the formation of the coating layer 40 is effectively promoted.

[0039] Although not particularly limited, the mist 7 in the preliminary step may be the same as the mist 7 in the film formation step. In this case, although not particularly limited, the preliminary step and the film formation step may be carried out continuously. However, as another embodiment, the mist 7 in the preliminary step may be different from the mist 7 in the film formation step. That is, the raw material solution 6 may be made different from each other between the preliminary step and the film formation step.

[0040] (Example 2) With reference to the drawings, the film forming apparatus 110 of Example 2 will be described. As shown in FIG. 5, the film forming apparatus 110 of this example forms a film 4 on the surface of a substrate 2 using the mist CVD method. The film forming apparatus 110 of Example 2 has the same basic structure as the film forming apparatus 10 of Example 1. In the following description, for the configurations common to Example 1, the same reference numerals will be used, and redundant descriptions will be avoided.

[0041] In the film forming apparatus 110 of this example, the film forming chamber 12 has a cylindrical configuration, and a heater 34 is provided around the film forming chamber 12. A part of the section HS of the mist supply path 30 is located inside the film forming chamber 12 and is surrounded by the heater 34. Thereby, the heater 34 can heat the substrate 2 on the stage 14 and also heat the mist supply path 30. As shown in FIG. 6, a part of the infrared rays R1 generated by the heater 34 passes through the mist supply path 30 and irradiates the mist 7. In addition, the mist supply path 30 heated by the heater 34 also generates infrared rays R2, and a part of the infrared rays R2 irradiates the mist 7. Thus, in the section HS of the mist supply path 30 heated by the heater 34, the infrared rays R1 and R2 are irradiated from the inner surface 30a of the mist supply path 30 toward the mist 7, and the mist 7 passing therethrough is also heated. Therefore, the section HS heated by the heater 34 is also referred to herein as the mist heating section HS.

[0042] Also in this example, in the mist heating section HS, the inner surface 30a of the mist supply path 30 is covered with a coating layer 40. The material constituting the coating layer 40 contains at least one of an oxide or a hydroxide of an element present in the mist 7. By previously forming the coating layer 40 on the inner surface 30a of the mist supply path 30, even if deposits derived from the mist 7 further adhere, the reduction width of the amount of heat (dose of infrared rays R1 and R2) transmitted from the inner surface 30a of the mist supply path 30 to the mist 7 becomes small. As a result, the temperature drop of the mist 7 supplied to the substrate 2 is also suppressed, and film formation under predetermined optimal conditions can be continued over a long period.

[0043] Next, with further reference to FIG. 7, a method of using the film forming apparatus 110 will be described. This method of use has a preliminary step and a film forming step performed after the preliminary step. As shown in FIG. 7, the preliminary step can be performed by removing the mist generation source 20 and the mist supply path 30 from the film forming chamber 12. In this case, a heater 134 for the preliminary step may be attached to the mist heating section HS. In the preliminary step, while operating the heater 134, the mist 7 generated by the mist generation source 20 is supplied to the mist supply path 30. Thereby, a coating layer 40 is formed on the inner surface 30a of the mist supply path 30, particularly on the inner surface 30a located in the mist heating section HS (see FIG. 6).

[0044] Thereafter, as shown in FIG. 5, in the film forming step, the mist generation source 20 and the mist supply path 30 are attached to the film forming chamber 12. Then, while operating the heater 34, the mist 7 generated by the mist generation source 20 is supplied to the film forming chamber 12 through the mist supply path 30. In the film forming chamber 12, the substrate 2 is placed on the stage 14, and the mist 7 supplied to the substrate 2 on the stage 14 forms the film 4 on the surface of the substrate 2. Also in this embodiment, since the coating layer 40 is previously formed on the inner surface 30a of the mist supply path 30, in the film forming step, film formation can be carried out with a stable film quality.

[0045] (Embodiment 3) With reference to the drawings, the film forming apparatus 210 of Embodiment 3 will be described. As shown in FIG. 8, the film forming apparatus 210 of this embodiment forms a film 4 on the surface of the substrate 2 using the mist CVD method. The film forming apparatus 210 of Embodiment 3 is common to the film forming apparatus 10 of Embodiment 1 in its basic structure. In the following description, for the configurations common to Embodiment 1, the same reference numerals will be used, and redundant description will be avoided.

[0046] In the film forming apparatus 210 of this embodiment, a part of the mist supply path 30 and the film forming chamber 12 are constituted by a common cylindrical member, and a heater 34 is provided around the cylindrical member. Therefore, in the film forming apparatus 210 of this embodiment, the boundary between the mist supply path 30 and the film forming chamber 12 is not particularly defined, and it can also be interpreted that the film forming chamber 12 is included in the mist supply path 30. As shown in FIG. 9, a part of the infrared ray R1 generated by the heater 34 passes through the mist supply path 30 and irradiates the mist 7. In addition, the mist supply path 30 heated by the heater 34 also generates an infrared ray R2, and a part of the infrared ray R2 irradiates the mist 7. Thus, in the section HS of the mist supply path 30 heated by the heater 34, the infrared rays R1 and R2 are irradiated from the inner surface 30a of the mist supply path 30 toward the mist 7, and the mist 7 passing therethrough is also heated. Therefore, the section HS heated by the heater 34 is also referred to herein as the mist heating section HS. Further, the heater 34 in this embodiment also functions as a heater for heating the substrate 2 on the stage 14.

[0047] Also in this embodiment, in the mist heating section HS, the inner surface 30a of the mist supply path 30 is covered with the coating layer 40. The material constituting the coating layer 40 contains at least one of the oxides or hydroxides of the elements present in the mist 7. By previously forming the coating layer 40 on the inner surface 30a of the mist supply path 30, even if deposits derived from the mist 7 further adhere, the reduction width of the amount of heat (dose of the infrared rays R1 and R2) transmitted from the inner surface 30a of the mist supply path 30 to the mist 7 becomes small. As a result, the temperature drop of the mist 7 supplied to the substrate 2 is also suppressed, and film formation under predetermined optimum conditions can be continued over a long period.

[0048] Next, with further reference to FIG. 10, a method of using the film forming apparatus 210 will be described. This method of use has a preliminary step and a film forming step carried out after the preliminary step. As shown in FIG. 10, in the preliminary step, the stage 14 can be removed from the film forming chamber 12. In the preliminary step, while operating the heater 134, the mist 7 generated by the mist generating source 20 is supplied to the mist supply path 30. Thereby, a coating layer 40 is formed on the inner surface 30a of the mist supply path 30, particularly on the inner surface 30a located in the mist heating section HS (see FIG. 9).

[0049] Thereafter, as shown in FIG. 8, in the film forming step, the stage 14 on which the substrate 2 is placed is disposed in the film forming chamber 12. Then, while operating the heater 34, the mist 7 generated by the mist generating source 20 is supplied to the film forming chamber 12 through the mist supply path 30. In the film forming chamber 12, the mist 7 supplied to the substrate 2 on the stage 14 forms the film 4 on the surface of the substrate 2. Also in this embodiment, since the coating layer 40 is previously formed on the inner surface 30a of the mist supply path 30, in the film forming step, film formation can be carried out with a stable film quality.

[0050] (Example 4) With reference to the drawings, the film forming apparatus 310 of Example 4 will be described. As shown in FIG. 11, the film forming apparatus 310 of this example forms the film 4 on the surface of the substrate 2 using the mist CVD method. The film forming apparatus 310 of Example 4 is common to the film forming apparatus 10 of Example 1 in its basic structure. In the following description, for the configurations common to Example 1, the same reference numerals will be used and duplicate description will be avoided.

[0051] In the film forming apparatus 310 of this example, the stage 14 is a turntable and a plurality of substrates 2 can be placed thereon. Further, in the film forming chamber 12, a duct 312 connected to the mist supply path 30 is provided, and the mist 7 from the mist supply path 30 is configured to be supplied to the substrate 2 on the stage 14 through the duct 312. In the mist supply path 30, an exhaust path 38 is provided via a branch valve 36, as in Example 1.

[0052] A heater 34 is provided in a partial section HS of the mist supply path 30. As shown in FIG. 12, a part of the infrared rays R1 generated by the heater 34 passes through the mist supply path 30 and irradiates the mist 7. In addition, the mist supply path 30 heated by the heater 34 also generates infrared rays R2, and a part of the infrared rays R2 is irradiated to the mist 7. Thus, in the section HS of the mist supply path 30 heated by the heater 34, the infrared rays R1 and R2 are irradiated from the inner surface 30a of the mist supply path 30 toward the mist 7, so that the mist 7 passing therethrough is also heated. Therefore, the section HS heated by the heater 34 is also referred to herein as the mist heating section HS.

[0053] Also in this embodiment, in the mist heating section HS, the inner surface 30a of the mist supply path 30 is covered with a coating layer 40. The material constituting the coating layer 40 contains at least one of an oxide or a hydroxide of an element present in the mist 7. By previously forming the coating layer 40 on the inner surface 30a of the mist supply path 30, even if deposits derived from the mist 7 further adhere, the reduction width of the amount of heat (dose of infrared rays R1 and R2) transmitted from the inner surface 30a of the mist supply path 30 to the mist 7 becomes small. As a result, the temperature drop of the mist 7 supplied to the substrate 2 is also suppressed, and film formation under predetermined optimal conditions can be continued over a long period.

[0054] Next, with further reference to FIG. 13, a method of using the film forming apparatus 310 will be described. This method of use has a preliminary step and a film forming step carried out after the preliminary step. As shown in FIG. 13, in the preliminary step, while operating the heater 34, the mist 7 generated by the mist generating source 20 is supplied to the mist supply path 30. Thereby, a coating layer 40 is formed on the inner surface 30a of the mist supply path 30, particularly on the inner surface 30a located in the mist heating section HS (see FIG. 12). The mist 7 that has passed through the mist heating section HS may be discharged to the outside through the exhaust path 38.

[0055] Thereafter, as shown in FIG. 11, in the film forming process, the mist generation source 20 and the mist supply path 30 are attached to the film forming chamber 12. Then, while operating the heater 34, the mist 7 generated by the mist generation source 20 is supplied to the film forming chamber 12 through the mist supply path 30. In the film forming chamber 12, the substrate 2 is placed on the stage 14, and the mist 7 supplied to the substrate 2 on the stage 14 forms a film 4 on the surface of the substrate 2. Also in this embodiment, by previously forming the coating layer 40 on the inner surface 30a of the mist supply path 30, film formation can be carried out with a stable film quality in the film forming process.

[0056] As described above, specific examples of the technology disclosed in this specification have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology illustrated in this specification or the drawings can achieve a plurality of purposes simultaneously, and achieving one of these purposes itself has technical utility.

Explanation of Reference Numerals

[0057] 2: Substrate, 4: Film, 6: Raw material solution, 7: Mist, 10, 110, 210, 310: Film forming apparatus, 12: Film forming chamber, 14: Stage, 20: Mist generation source, 30: Mist supply path, 34: Heater Coating layer: 40 R1, R2: Infrared rays

Claims

1. A film forming apparatus (10, 110, 210, 310) for forming a film (4) on the surface of a substrate (2), a stage (14) on which the substrate is placed, a mist generating source (20) that generates a mist (7) of a solution (6) in which the material constituting the film is dissolved and that contains at least water, a supply path (30) that conveys the mist generated by the mist generating source to the substrate on the stage by the flow of a carrier gas, a heater (34) that heats at least a part of the supply path, comprising: a section of the supply path heated by the heater is a mist heating section (HS) irradiated with infrared rays (R1, R2) from the inner surface (30a) of the supply path toward the mist, in the mist heating section, the inner surface of the supply path is covered with a coating layer (40) containing at least one of an oxide or a hydroxide of an element present in the mist, the coating layer in the mist heating section has an absorption rate of 50 percent or more with respect to the infrared rays irradiated from the inner surface of the supply path toward the mist, film forming apparatus.

2. The film forming apparatus according to claim 1, wherein the coating layer is composed only of elements contained in the mist.

3. The supply path includes a film forming chamber (12) in which the stage is disposed, when the temperature of the substrate during film formation is T1 and the temperature T2 of the inner surface of the film forming chamber facing the surface of the substrate is defined, the film forming apparatus according to claim 1 or 2, satisfying T1 > T2.

4. The film forming apparatus according to any one of claims 1 to 3, wherein the film formed on the surface of the substrate is an epitaxial film.

5. The film forming apparatus according to any one of claims 1 to 4, wherein the inner surface of the supply path in the mist heating section is made of quartz.

6. The film forming apparatus according to claim 5, wherein the quartz contains a hydroxyl group (OH group).

7. The film forming apparatus according to any one of claims 1 to 6, when the temperature of the heater is T3, satisfying T3 ≥ 100°C.

8. The supply path includes a film forming chamber in which the stage is disposed, when the temperature of the inner surface of the film forming chamber is T2 and the temperature T3 of the heater is defined, the film forming apparatus according to any one of claims 1 to 7, satisfying the relationship T2 < T3.

9. The wavelength λ of the infrared rays irradiated onto the mist satisfies λ ≤ 7.8 micrometers, and the film forming apparatus according to any one of claims 1 to 8.

10. A method of using a film forming apparatus for forming a film on the surface of a substrate, wherein the film forming apparatus includes a stage on which the substrate is placed, a mist generation source that dissolves the material constituting the film and generates a mist of a solution containing at least water, a supply path that conveys the mist generated by the mist generation source to the substrate on the stage by the flow of a carrier gas, a heater that heats at least a part of the supply path, and is provided with a section of the supply path heated by the heater is a mist heating section where infrared rays are irradiated from the inner surface of the supply path toward the mist, the method of use includes a preliminary step of supplying the mist generated by the mist generation source to the mist heating section while operating the heater to form a coating layer on the inner surface of the mist heating section, a film forming step that is performed after the preliminary step and supplies the mist generated by the mist generation source to the substrate on the stage through the supply path while operating the heater to form the film on the surface of the substrate, and is provided with when the temperature of the inner surface of the mist heating section in the preliminary step is T4 and the temperature of the heater in the film forming step is T3, the relationship T3 < T4 is satisfied, Method of use.

11. A method of using a film forming apparatus for forming a film on the surface of a substrate, wherein the film forming apparatus includes a stage on which the substrate is placed, a mist generation source that dissolves the material constituting the film and generates a mist of a solution containing at least water, a supply path that conveys the mist generated by the mist generation source to the substrate on the stage by the flow of a carrier gas, a heater that heats at least a part of the supply path, and is provided with a section of the supply path heated by the heater is a mist heating section where infrared rays are irradiated from the inner surface of the supply path toward the mist, the method of use includes a preliminary step of supplying the mist generated by the mist generation source to the mist heating section while operating the heater to form a coating layer on the inner surface of the mist heating section, A film forming step that is carried out after the preliminary step, while operating the heater, supplies the mist generated at the mist generation source to the substrate on the stage through the supply path, and forms the film on the surface of the substrate. It is provided with When the temperature of the inner surface of the mist heating section in the preliminary step is T4 and the temperature of the substrate in the film forming step is T1, the relationship T1 < T4 is satisfied. Usage method.

12. The usage method according to claim 10 or 11, wherein the mist in the preliminary step is the same as the mist in the film forming step.

13. The usage method according to any one of claims 10 to 12, wherein the preliminary step and the film forming step are carried out continuously.

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