JP7833859B2 - Thin film deposition apparatus and thin film deposition method - Google Patents

Description

This invention relates to a film deposition apparatus.

A film deposition apparatus for forming a film by adhering particles of a film-forming material to an object is known, as described in Patent Document 1. This apparatus generates plasma in a chamber using a plasma gun, and evaporates the film-forming material within the chamber. The film-forming material adheres to the substrate, forming a film on the substrate.

Japanese Patent Publication No. 2016-141856

Here, the aforementioned film deposition apparatus has a gas supply unit that supplies oxygen gas, which contains the elements that make up the film, into the chamber. In the aforementioned film deposition apparatus, the gas supply unit supplies the gas to the area near the transport unit that transports the substrate within the chamber. In such a film deposition apparatus, there was a need to further improve the film quality.

Therefore, the object of this invention is to provide a film deposition apparatus capable of improving film quality.

The film deposition apparatus according to the present invention is a film deposition apparatus for depositing particles of a film deposition material onto an object to form a film, and comprises a plasma generation unit that generates plasma, an electrode capable of holding the film deposition material and guiding the plasma to the film deposition material, and a gas supply unit that supplies a gas containing elements constituting the film from the electrode side toward the plasma guided to the electrode.

For example, if the gas supply unit uniformly supplies a gas containing the elements constituting the film into the chamber, the gas diffuses throughout the chamber and reacts with the plasma to undergo dissociation and ionization. However, the elemental activity may be insufficient or inefficient. In this case, elemental defects may occur in the film of the target object. In contrast, in the film deposition apparatus according to the present invention, the gas supply unit supplies a gas containing the elements constituting the film from the electrode side toward the plasma leading to the electrode. In this case, the gas supply unit can supply gas to regions with high plasma density. Since the activity of the gas supplied to these regions is improved, elemental defects in the film of the target object can be suppressed. As a result, the film quality can be improved.

The gas supply unit may supply gas from the opposite side of the direction of plasma propagation to the electrode receiving the plasma, at the electrode's position. In this case, the gas supply unit can more easily supply gas to regions with high plasma density.

The electrode may have a channel for passing gas through, and the gas may be supplied from the outlet of the channel. In this case, since the gas can be supplied from the electrode's position, it becomes possible to supply gas to the region with high plasma density near the electrode.

The gas supply unit may supply gas from a position radially away from the electrode, at a distance of no more than 1.5 times the electrode's diameter. This allows the gas supply unit to supply gas from a position close to the electrode, enabling gas to be supplied to regions with high plasma density.

The film deposition apparatus according to any one of claims 1 to 4, wherein the gas supply unit supplies the gas from a position radially away from the electrode by a distance of 70 mm or less. This allows the gas supply unit to supply gas from a position close to the electrode, thereby enabling the supply of gas to regions with high plasma density.

The electrode is provided with a cylindrical member surrounding it, and the gas supply unit may supply gas from between the electrode and the cylindrical member. In this case, since the gas supply unit can supply gas from a position close to the electrode, it can supply gas to regions with high plasma density. Furthermore, the cylindrical member allows for the easy formation of a gas flow path.

The plasma generation unit may be a pressure gradient type plasma gun. In this case, a region with high plasma density can be created near the electrodes.

The system may further include auxiliary electrodes surrounding the main electrode, and the gas supply unit may supply gas from the inner circumference of the auxiliary electrode. The inner side of the auxiliary electrode is close to the main electrode. Therefore, since the gas supply unit can supply gas from a position close to the main electrode, it can supply gas to regions with high plasma density.

The gas supply unit comprises a first supply unit and a second supply unit that supplies gas at a position closer to the electrode than the first supply unit. The gas supply rate of the second supply unit is greater than that of the first supply unit. In this way, a large amount of gas can be supplied to areas with high plasma density.

According to the present invention, a film deposition apparatus capable of improving film quality is provided.

This is a schematic cross-sectional view showing the configuration of a film deposition apparatus according to an embodiment of the present invention. This is a schematic diagram showing an enlarged cross-section of the main hearth and an overview of the reactive gas flow path thereto. This is a schematic diagram showing the configuration of the gas supply unit when a ring hearth is included. This diagram shows how a flow path is formed in the main hearth. This diagram shows the cylindrical member that covers the main hearth. This is a schematic diagram showing how gas is supplied to a location adjacent to the main hearth using pipes. This figure shows experimental examples of both experimental and comparative examples. This is a schematic cross-sectional view of a modified film deposition apparatus.

The following describes a film deposition apparatus according to one embodiment of the present invention, with reference to the attached drawings. In the description of the drawings, identical elements are denoted by the same reference numerals, and redundant explanations are omitted.

First, with reference to Figure 1, the configuration of the film deposition apparatus according to the present invention will be described. Figure 1 is a schematic cross-sectional view showing the configuration of the film deposition apparatus 1 according to this embodiment. The film deposition apparatus 1 is an apparatus that forms a film by attaching particles of film deposition material to an object. As shown in Figure 1, the film deposition apparatus 1 of this embodiment is an ion plating apparatus used in the so-called ion plating method. For the sake of explanation, Figure 1 shows an XYZ coordinate system. The Y-axis direction is the direction in which the substrate, which will be described later, is transported. The Z-axis direction is the position where the substrate and the hearth mechanism, which will be described later, face each other. The X-axis direction is the direction perpendicular to the Y-axis direction and the Z-axis direction.

The film deposition apparatus 1 is a so-called horizontal type, in which the substrate 11 is placed and transported within the vacuum chamber 10 so that the thickness direction of the substrate 11 is approximately vertical. In this case, the X and Y axis directions are horizontal, and the Z axis direction is vertical and in the thickness direction. Alternatively, the film deposition apparatus 1 may be a so-called vertical type, in which the substrate 11 is placed and transported within the vacuum chamber 10 in an upright or inclined position so that the thickness direction of the substrate 11 is horizontal (Z axis direction in Figures 1 and 2). In this case, the Z axis direction is horizontal and in the thickness direction of the substrate 11, the Y axis direction is horizontal, and the X axis direction is vertical.

The film deposition apparatus 1 forms a film on the surface of the substrate 11 by supplying particles Mb of the film deposition material Ma to the substrate 11. The film deposition apparatus 1 comprises a vacuum chamber 10 (chamber), a transport mechanism 3, a film deposition mechanism 14, an inert gas supply unit 30, a reactive gas supply unit 40 (gas supply unit), and a current supply unit 80.

The vacuum chamber 10 is a component for housing the substrate 11 and performing film deposition. The vacuum chamber 10 includes a transport chamber 10a for transporting the substrate 11 on which the film deposition material Ma is formed, a deposition chamber 10b for diffusing the film deposition material Ma, and a plasma port 10c for receiving the plasma P irradiated in a beam shape from the plasma gun 7 into the vacuum chamber 10. The transport chamber 10a, deposition chamber 10b, and plasma port 10c are interconnected. The transport chamber 10a is set along the Y-axis in a predetermined transport direction (arrow A in the figure). The transport chamber 10a has elongated walls 10d and 10e facing each other in the Z-axis direction and a wall facing each other in the X-axis direction. The vacuum chamber 10 is made of a conductive material and is connected to ground potential.

The film deposition chamber 10b has a wall section 10W comprising a pair of side walls aligned with the transport direction (arrow A), a pair of side walls 10h and 10i aligned with the direction intersecting the transport direction (arrow A) (Z-axis direction), and a bottom wall 10j positioned along the X-axis direction.

The transport mechanism 3 transports the substrate holding member 16, which holds the substrate 11 facing the film-forming material Ma, in the transport direction (arrow A). For example, the substrate holding member 16 is a frame that holds the outer edge of the substrate 11. The transport mechanism 3 is composed of a plurality of transport rollers 15 installed in the transport chamber 10a. The transport rollers 15 are arranged at equal intervals along the transport direction (arrow A) and transport the substrate holding member 16 in the transport direction (arrow A) while supporting it. The substrate 11 is, for example, a plate-shaped material such as a glass substrate or a plastic substrate.

Next, the configuration of the film deposition mechanism 14 will be described in detail. The film deposition mechanism 14 deposits particles of the film deposition material Ma onto the substrate 11 using an ion plating method. The film deposition mechanism 14 includes a plasma generation unit 18, a steering coil 5, a hearth mechanism 2, and a ring hearth 6.

The plasma generation unit 18 generates plasma within the vacuum chamber 10. The plasma generation unit 18 includes, for example, a pressure gradient type plasma gun 7. The plasma gun 7 is connected to the deposition chamber 10b via a plasma port 10c located on the side wall of the deposition chamber 10b. The plasma gun 7 generates plasma P within the vacuum chamber 10. The plasma P generated in the plasma gun 7 is emitted in a beam-like manner from the plasma port 10c into the deposition chamber 10b. This generates plasma P within the deposition chamber 10b.

The plasma gun 7 has one end closed by a cathode 60. Between the cathode 60 and the plasma port 10c, a first intermediate electrode (grid) 61 and a second intermediate electrode (grid) 62 are concentrically arranged. The first intermediate electrode 61 contains a ring-shaped permanent magnet 61a for focusing the plasma P. The second intermediate electrode 62 also contains an electromagnet coil 62a for focusing the plasma P.

The steering coil 5 is positioned around the plasma port 10c, where the plasma gun is mounted. The steering coil 5 guides the plasma P into the deposition chamber 10b. The steering coil 5 is energized by a power supply (not shown) for the steering coil.

The hearth mechanism 2 holds the film deposition material Ma. The hearth mechanism 2 is located within the film deposition chamber 10b of the vacuum chamber 10 and is positioned in the negative direction of the Z-axis when viewed from the transport mechanism 3. The hearth mechanism 2 has a main hearth 17 (electrode) which is either a main anode that guides the plasma P emitted from the plasma gun 7 to the film deposition material Ma, or a main anode to which the plasma P emitted from the plasma gun 7 is guided.

The main hearth 17 is a cylindrical member extending in the positive Z-axis direction and filled with the film-forming material Ma. Since the main hearth 17 is maintained at a positive potential relative to the ground potential of the vacuum chamber 10, it acts as the anode in the discharge, attracting the plasma P. A through-hole 17a is formed in the main hearth 17 into which the plasma P is incident, for filling it with the film-forming material Ma. The leading edge of the film-forming material Ma is exposed to the film-forming chamber 10b at one end of this through-hole 17a. In this way, the main hearth 17 can hold the film-forming material Ma by being filled with it. Furthermore, one end of the through-hole 17a serves as a holding position for the film-forming material Ma to be sublimated.

The film deposition material Ma is not particularly limited and can be appropriately selected according to the desired film. Examples include oxide semiconductor In2O3-based materials (Sn-doped ITO (indium tin oxide), W-doped IWO (tungsten-doped indium oxide)), conductive materials such as ZnO, metallic materials, and insulating encapsulating materials such as SiON. Other materials such as Ga2O3, GaN, Al, AlN, and SiC can also be used as the film deposition material Ma, but are not particularly limited. When the film deposition material Ma is an insulating material, when the plasma P beam is irradiated onto the main hearth 17, the main hearth 17 is heated by the current from the plasma P beam, the leading edge of the film deposition material Ma evaporates, and ionized particles Mb diffuse into the film deposition chamber 10b. Furthermore, when the film deposition material Ma is made of a conductive material, when the plasma P beam is irradiated onto the main hearth 17, the plasma P beam directly enters the film deposition material Ma, heating and evaporating the leading edge of the film deposition material Ma, and ionized particles Mb diffuse into the deposition chamber 10b. The particles Mb diffused in the deposition chamber 10b move in the positive Z-axis direction of the deposition chamber 10b and adhere to the surface of the substrate 11 within the transport chamber 10a. The film deposition material Ma is a solid object molded into a cylindrical shape of a predetermined length, and multiple pieces of film deposition material Ma are filled into the hearth mechanism 2 at once. Then, in accordance with the consumption of film deposition material Ma, the film deposition material Ma is sequentially pushed out from the negative Z-direction side of the hearth mechanism 2 so that the leading edge of the film deposition material Ma maintains a predetermined positional relationship with the upper end of the main hearth 17.

The ring hearth 6 (auxiliary electrode) is an auxiliary anode having an electromagnet for inducing plasma P. The ring hearth 6 is provided so as to surround the main hearth 17. The ring hearth 6 is positioned around the main hearth 17 that holds the film-forming material Ma. The ring hearth 6 has an annular coil 9, an annular permanent magnet section 20, and an annular container 12, with the coil 9 and permanent magnet section 20 housed in the container 12. In this embodiment, the coil 9 and permanent magnet section 20 are arranged in the negative Z direction as viewed from the transport mechanism 3, but they may also be arranged in the negative Z direction, with the permanent magnet section 20 and coil 9. The ring hearth 6 controls the direction of the plasma P incident on the film-forming material Ma, or the direction of the plasma P incident on the main hearth 17, according to the magnitude of the current flowing through the coil 9. The potentials of the main hearth 17 and the ring hearth 6 are controlled based on control signals from a control unit (not shown).

In this embodiment, the plasma gun 7 emits plasma P from the side wall 10h toward the positive side in the Y-axis direction. Meanwhile, the main hearth 17 is positioned on the bottom wall 10j side, with its tip facing toward the positive side in the Z-axis direction. Between the plasma gun 7 and the main hearth 17, a plasma discharge occurs with the plasma gun 7 as the cathode and the main hearth 17 (and the deposition material Ma) as the anode. The plasma P travels from the plasma gun 7 toward the positive side in the Y-axis direction, then curves toward the negative side in the Z-axis direction, and continues toward the main hearth 17. As a result, a plasma discharge region is formed in the deposition chamber 10b between the main hearth 17 and the transport mechanism 3, where the plasma discharge occurs.

The main hearth 17 and the ring hearth 6 are arranged on a partition wall 25. The partition wall 25 is a wall that separates the space where the plasma P reaction takes place from the space through which the inert gas flows. The partition wall 25 is positioned at an upper distance from the bottom wall 10j. The partition wall 25 is positioned to form a gap between itself and the side walls 10h and 10i.

The inert gas supply unit 30 supplies inert gas into the vacuum chamber 10. Examples of substances included in the inert gas include noble gases such as argon and helium. The reactive gas supply unit 40 supplies reactive gas into the vacuum chamber 10. The reactive gas is a gas that reacts with the plasma and contains elements that constitute the film. When forming films such as ITO or IWO, oxygen gas is used as the reactive gas. The gas supply units 30 and 40 supply inert gas and oxygen gas at flow rates based on control signals from a control unit (not shown). The control unit can control the flow rate ratio of the reactive gas to obtain good film quality. The flow rate ratio of the reactive gas is the ratio of the reactive gas to the total flow rate of the inert gas and reactive gas.

The inert gas supply unit 30 comprises an inert gas supply source 31 and a supply channel 32. The supply channel 32 supplies inert gas from the inert gas supply source 31 into the space between the bottom wall 10j and the partition wall 25. This supplies the inert gas to the film deposition chamber 10b through the gap between the partition wall 25 and the side wall of the vacuum chamber 10 (see G1 in Figure 1).

The reactive gas supply unit 40 comprises a reactive gas supply source 41, a first supply unit 42, and a second supply unit 43. The first supply unit 42 and the second supply unit 43 inject (supply) reactive gas from the reactive gas supply source 41 to the film deposition chamber 10b (see G2 in Figure 1). The second supply unit 43 supplies the reactive gas at the location of the main hearth 17, or at a location adjacent to the main hearth 17 (details will be described later). In contrast, the first supply unit 42 supplies the reactive gas on the outer circumference side of the ring hearth 6. Therefore, the second supply unit 43 injects the reactive gas at a location closer to the main hearth 17 than the first supply unit 42. It is preferable that the gas supply amount of the second supply unit 43 is greater than that of the first supply unit 42.

In this embodiment, oxygen gas is given as the gas containing the elements that make up the film. However, the elements contained in the gas may be appropriately changed depending on the composition of the film. For example, when forming films such as SiON or AlN, nitrogen gas may be used as the reactive gas.

The current supply unit 80 supplies current to the plasma gun 7 for ionizing the film-forming material. The current supply unit 80 also supplies current to the cathode 60 of the plasma gun 7. As a result, the plasma gun 7 discharges at a predetermined discharge current value. The current supply unit 80 supplies current based on a control signal from a control unit (not shown).

Next, with reference to Figure 2, an overview of the reactive gas supply mechanism by the reactive gas supply unit 40 will be described. Figure 2 is a schematic diagram showing an enlarged cross-section of the main hearth 17 and an overview of the reactive gas flow path thereto.

The main hearth 17 shown in Figure 2 comprises a cylindrical portion 51 and a bottom flange portion 52. The cylindrical portion 51 has a tip surface 53, an outer circumferential surface 54, and an inclined surface 56. The tip surface 53 is an annular plane perpendicular to the center line CL1 of the cylindrical portion 51. The outer circumferential surface 54 is a cylindrical surface extending parallel to the center line CL1. The inclined surface 56 is formed between the tip surface 53 and the outer circumferential surface 54 and is a frustoconical surface that tapers towards the tip surface 53.

The plasma P from the plasma gun travels in the direction D1 toward the main hearth 17 (the negative side in the Z-axis direction in Figure 1) along the center line CL1, and is received by the tip surface 53 of the main hearth 17 (and the tip surface of the deposition material Ma). As a result, the region directly above the main hearth 17 becomes a region with high plasma density.

In contrast, the reactive gas supply unit 40 emits reactive gas from the main hearth 17 side toward the plasma P being guided to the main hearth 17. The gas supply unit 40 emits the reactive gas from the opposite side of the direction of plasma P propagation D1 to the main hearth 17, at a position on the main hearth 17 side receiving the plasma P. The gas supply unit 40 emits the reactive gas toward the transport mechanism 3 (see Figure 1) in the direction in which the center line CL1 extends. In the region directly above the main hearth 17, the plasma P and the reactive gas face each other and propagate in opposite directions. As a result, the reactive gas is supplied to the region directly above the main hearth 17 where the plasma density is high. In this region of high plasma density, the molecules of the reactive gas undergo high-activity dissociation and ionization.

The reactive gas supply unit 40 discharges the reactive gas from the location of the main hearth 17, or from a location adjacent to the main hearth 17. For example, the main hearth 17 has channels 60A, 60B, and 60C through which the reactive gas passes. The reactive gas supply unit 40 can discharge the reactive gas from the outlets 60a of the channels 60A, 60B, and 60C. Channel 60A is a channel formed within the wall thickness of the cylindrical portion 51 of the main hearth 17. Channel 60B is a channel formed at the boundary between the main hearth 17 and the film-forming material Ma, i.e., on the inner circumferential surface of the through-hole 17a. Channel 60C is a channel formed in the internal space of the through-hole 17a.

The reactive gas supply unit 40 has a flow path 60D located adjacent to the main hearth 17, and reactive gas can be discharged from the outlet 60a of the flow path 60D. Here, the location adjacent to the main hearth 17 is a location on the inner circumference side of the boundary line BL that defines the main hearth adjacent region. It is sufficient that the outlet 60a of the flow path 60D is located on the inner circumference side of the boundary line BL; intermediate flow paths 60D may be located on the outer circumference side of the boundary line BL. The boundary line BL may be set, for example, at a predetermined distance PD from the main hearth 17 in the radial direction. The predetermined distance PD is the radial distance from the outer peripheral edge of the tip surface 53 of the main hearth 17, which is the surface that receives the plasma P.

The predetermined distance PD may be 1.5 times the diameter of the main hearth 17. This allows the gas supply unit 40 to emit the reactive gas from a position radially away from the main hearth 17, at a distance of 1.5 times or less the diameter of the main hearth 17. The diameter of the main hearth 17 refers to the diameter of the outer edge of the tip surface 53, which receives the plasma P. The diameter of the film-forming material Ma may be set to approximately 20 to 40 mm, and the diameter of the through-hole 17a in the main hearth 17 can be changed depending on the situation. Since the mean free path, described later, is approximately 1.5 times the diameter of the through-hole 17a, the gas supply unit 40 emits the reactive gas from a position radially away from the main hearth 17, at a distance of 1.5 times or less the diameter of the main hearth 17.

Alternatively, the predetermined distance PD of the boundary line BL may be set to a specific value of 70 mm. This value may be defined as the mean free path that the introduced reactive gas can travel without colliding with other gases in the vacuum chamber 10. The mean free path is shown by the following equation (1). Although the atomic and molecular diameters differ depending on the type, the gases used are argon, oxygen, nitrogen, etc., so if the room temperature is approximately 27°C, the distance will be approximately 70 mm when the pressure in the vacuum chamber 10 is 0.1 Pa, and approximately 10 mm when it is 0.6 Pa. That is, if the pressure range is in the range of 0.1 to 0.6 Pa, the predetermined distance PD can be set to approximately 10 mm to 70 mm. Therefore, it is preferable that the outlet 60a of the flow path 60D be located at a position of 70 mm or less from the main hearth 17, and more preferably at a position of 10 mm or less. The predetermined distance PD may be adjusted according to the pressure in the vacuum chamber 10. Therefore, the gas supply unit 40 emits reactive gas from a position radially away from the main hearth 17 by a distance of 70 mm or less, more preferably 10 mm or less.

λ=1/(√2×π×σ×n) …(1)
σ: Diameter of an atom or molecule of a gas species; n: Density

Furthermore, when a ring hearth 6 is provided as in this embodiment, the position of the inner circumference of the ring hearth 6 may be defined as a position adjacent to the main hearth 17, as shown in Figure 3(a). In this case, the flow path 60D is positioned radially between the ring hearth 6 and the main hearth 17. As a result, the gas supply unit 40 discharges the reactive gas from the inner circumference of the ring hearth 6. Also, as shown in Figure 3(b), a replaceable outer rim 70 for depositing the material 71 may be provided between the main hearth 17 and the ring hearth 6. In this case, the gas supply unit 40 may discharge the reactive gas from the gap between the main hearth 17 and the outer rim 70. Note that if the film deposition material Ma is a conductive material, if the deposited material 71 grows too far inward, it can cause a short circuit between the main hearth 17 and the ring hearth 6. Also, the grown deposited material 71 may interfere with the diffusion of evaporated particles Mb. Therefore, continuous operation is possible by periodically replacing the outer rim 70.

Figure 4 shows an example of a flow channel 60B formed in the main hearth 17. As shown in Figure 4(b), the flow channel 60B is provided by forming an axially extending notch in a part of the inner circumferential surface of the through-hole 17a. Here, four flow channels 60B are provided, but the number is not particularly limited. As shown in Figure 4(a), at the lower end of the through-hole 17a, the flow channel 60B wraps around to the lower surface of the flange portion 52 and extends downward through the partition wall 25. The routing of the flow channel 60B is not particularly limited. Note that the film-forming material Ma may adhere to the flow channel 60B; however, this adhesion can be avoided by providing a flow channel 60A (see Figure 2) within the main hearth 17 component. However, flow channels 60B are easier to manufacture than flow channels 60A.

A flow path 60D may be provided by a double-cylinder structure as shown in Figure 5. As shown in Figure 5, the main hearth 17 is provided with a cylindrical member 86 that surrounds the main hearth 17. The cylindrical member 86 has a main body portion 81 that covers the cylindrical portion 51 and a flange portion 82 that covers the flange portion 52. The main body portion 81 is positioned to form a gap 85 between itself and the cylindrical portion 51. This gap 85 is provided around the entire circumference of the main hearth 17, and this gap 85 is configured as the flow path 60D. The flange portion 82 is fixed to the flange portion 52 via torque-controlled bolts 83. As a result, the gas supply unit 40 injects reactive gas from between the main hearth 17 and the cylindrical member 86. In this case, the flow path 60D can be formed to surround the entire circumference of the main hearth 17, so that the reactive gas can be supplied evenly. The material of the cylindrical member 86 is not particularly limited and may be the same material as the main hearth 17 or a different material. If the cylindrical member 86 is made of a conductive material, the cylindrical member 86 can also function as part of the main hearth. In this case, the gap 85 can be considered as a flow path 60A formed within the wall thickness of the main hearth 17.

As shown in Figure 6, the flow path 60D, located adjacent to the main hearth 17, may be composed of a pipe 90. As shown in Figure 6(a), the pipe 90 may be attached to the main hearth 17 by brazing or welding. In this case, the distance from the outer edge of the tip surface 53 of the outlet 60a of the flow path 60D will be equal to the thickness of the pipe 90. Multiple pipes 90 may be provided relative to the main hearth 17. Since the pipe 90 is attached to the main hearth 17, no cooling problems arise. As shown in Figure 6(b), the pipe 90 may be positioned radially away from the main hearth 17. In this case, the arrangement should be adjusted to prevent overheating by the plasma P. As shown in Figure 6, the reactive gas does not need to be discharged parallel to the axial direction in the flow path 60D; it may be discharged at an angle to the axial direction.

Next, the experimental results confirming the effectiveness of the film deposition apparatus 1 according to this embodiment will be explained with reference to Figure 7. Figure 7 shows the experimental results when ITO film deposition was performed. Resistivity, mobility, and carrier density are shown as indicators of the film quality of ITO, which is a transparent conductive film. The optimal values for each parameter differ depending on the application, but when used as a conductive film, a lower resistivity is desirable, and it is desirable to increase the mobility without changing the carrier density from the conventional value. Here, as a comparative example, a film deposition apparatus in which oxygen is supplied to the entire vacuum chamber 10, similar to the inert gas in Figure 1, was adopted. In Figure 7, the solid line graph shows the comparative example. As an example, a film deposition apparatus in which oxygen is supplied from between the main hearth 17 and the outer rim 70 (see Figure 3(b)) was adopted. In Figure 7, the dashed line graph shows the example. The horizontal axis of the graph in Figure 7 shows the ratio of the oxygen gas flow rate to the total gas flow rate (argon + oxygen) introduced into the vacuum chamber 10. The _O2 flow rate ratio is given by ( _O2 gas flow rate / (Ar gas flow rate + _O2 gas flow rate)). As shown in Figures 7(a) to (c), the carrier density of the example did not change significantly from that of the comparative example, but the resistivity and mobility of the example were improved compared to the comparative example. Therefore, it was shown that the crystallinity of the film deposited in the example's deposition apparatus was improved. Consequently, it was shown that introducing oxygen from the vicinity of the main hearth 17 was more efficient in terms of oxygen utilization than introducing oxygen into the entire vacuum chamber 10.

Next, the operation and effects of the film deposition apparatus 1 according to this embodiment will be described.

For example, if the gas supply unit 40 supplies a gas containing the elements constituting the film uniformly into the vacuum chamber 10, the gas diffuses throughout the vacuum chamber 10 and reacts with the plasma to undergo dissociation and ionization. However, the activity of the elements may be insufficient or inefficient. In this case, elemental defects may occur in the film on the substrate 11. For example, In is easily positively ionized, and the positive ionization of oxygen is insufficient with only the oxygen obtained by evaporating the film-forming material Ma. In contrast, in the film-forming apparatus 1 according to this embodiment, the gas supply unit 40 supplies a gas containing the elements constituting the film from the main hearth 17 side toward the plasma P led to the main hearth 17. In this case, the gas supply unit 40 can supply gas to regions with high plasma density. Since the activity of the gas supplied to these regions is improved, elemental defects in the film on the substrate 11 can be suppressed. As a result, the film quality can be improved.

The gas supply unit 40 may emit (supply) gas from the opposite side of the direction of plasma P's propagation D1 to the main hearth 17, at a position on the main hearth 17 side receiving the plasma P. In this case, the gas supply unit 40 can more easily supply gas to regions with high plasma density.

The main hearth 17 has gas passages 60A, 60B, and 60C, and may be capable of ejecting gas from the outlets 60a of these passages 60A, 60B, and 60C. In this case, since the gas can be ejected from the position of the main hearth 17, it becomes possible to eject the gas into a region with high plasma density near the main hearth 17.

The gas supply unit 40 may emit gas from a position radially away from the main hearth 17, at a distance of no more than 1.5 times the diameter of the main hearth 17. This allows the gas supply unit 40 to supply gas from a position close to the main hearth 17, enabling gas emission into regions with high plasma density.

The film deposition apparatus according to any one of claims 1 to 4, wherein the gas supply unit 40 emits the gas from a position radially away from the electrode by a distance of 70 mm or less. This allows the gas supply unit to supply gas from a position close to the electrode, enabling the gas to be emitted into a region with high plasma density.

The main hearth 17 is provided with a cylindrical member 86 that surrounds it, and the gas supply unit 40 may emit gas from between the main hearth 17 and the cylindrical member 86. In this case, the gas supply unit 40 can supply gas from a position close to the main hearth 17, allowing the gas to be emitted into a region with high plasma density. Furthermore, the cylindrical member 86 can be used to easily form a gas flow path.

The plasma generation unit 18 may be a pressure gradient type plasma gun 7. In this case, a region with high plasma density can be created near the main hearth 17.

In the pressure gradient type plasma gun 7, the internal pressure of the plasma gun 7 is higher than the pressure of the deposition chamber. Therefore, the gas introduced from the gas supply unit 40 does not enter the plasma gun 7. The cathode of the plasma gun 7 is composed of LaB6 and Ta, and the plasma is generated mainly by the supply of thermionic electrons by LaB6. For example, if the reactive gas is oxygen, it will be hot when it reaches LaB6 and Ta, causing it to oxidize rapidly, become insulated, and discharge will become impossible. In effect, it is impossible to perform arc discharge while freely adjusting the oxygen gas in the deposition chamber with other devices. In addition, the pressure gradient type plasma gun 7 is characterized by its very high plasma density ( ^10¹² to ^{10¹³ cm⁻³} ) and high reactivity. Furthermore, since the cathode is not oxidized, it has the advantage of a long lifespan.

In the case of DC sputtering equipment (although the positive and negative relationships are reversed), if the target is a metal and the reactive gas is oxygen, the target will oxidize, making discharge impossible (or extremely difficult). In other words, sputtering becomes impossible (or extremely slow). If the metal oxide is not an insulating material, discharge can continue, but it will be slow. This is known as the metal mode, intermediate mode, and oxide mode, and the deposition rate follows the order of metal, intermediate, and oxide. Because the amount of oxygen is adjusted during deposition to prevent complete oxidation, there is a limit to the amount of oxygen that can be supplied, making oxygen loss from the formed film very likely. RF sputtering equipment can sputter even insulating targets, but the deposition rate is slower compared to DC. Compared to these deposition equipment, the deposition equipment 1 using a pressure gradient type plasma gun 7 can overcome the problems described above.

The system further includes a ring hearth 6 surrounding the main hearth 17, and the gas supply unit 40 may emit gas from the inner circumference of the ring hearth 6. The inner side of the ring hearth 6 is close to the main hearth 17. Therefore, since the gas supply unit 40 can supply gas from a position close to the main hearth 17, it can emit gas into regions with high plasma density.

The gas supply unit 40 comprises a first supply unit 42 and a second supply unit 43 that emits gas at a position closer to the main hearth 17 than the first supply unit 42. The gas supply amount of the second supply unit 43 is greater than that of the first supply unit 42. In this way, a large amount of gas can be supplied to areas with high plasma density.

The present invention is not limited to the embodiments described above.

For example, the above-described embodiment described a molding apparatus having a ring hearth 6. Alternatively, as shown in Figure 8, a film deposition apparatus 100 without a ring hearth 6 may be used. The main hearth 117 has a crucible-like shape. A magnet section 109 is provided below the main hearth 117. In this film deposition apparatus 100 as well, the reactive gas supply unit 40 can supply reactive gas at the location of the main hearth 117, or at a location adjacent to the main hearth 117. By supplying reactive gas at the location of the main hearth 117, or at a location adjacent to the main hearth 117, it is possible to employ flow paths similar in purpose to the flow paths 60A, 60B, 60C, and 60D shown in Figure 2.

Furthermore, a mechanism for mixing the reactive gas supply source and the inert gas supply source may be employed. The reactive gas and inert gas may be mixed at a single gas supply port. For example, the inert gas may be mixed and supplied to the outlet 60a of the reactive gas supply unit 40 described above.

1,100…Film deposition apparatus, 6…Wheel hearth (auxiliary electrode), 7…Plasma gun, 17…Main hearth (electrode), 11…Substrate (object), 40…Reactive gas supply unit (gas supply unit), 42…First supply unit, 43…Second supply unit, 60A, 60B, 60C, 60D…Flow channels, 80…Cylindrical member, Ma…Film deposition material, Mb…Particles.

Claims (10)

A film deposition apparatus that forms a film by attaching particles of a film-forming material to an object,
A plasma generation unit that generates plasma,
An electrode positioned at a distance from the plasma generation unit, which holds the film-forming material during film formation and guides the plasma to the film-forming material, thereby causing the film-forming material to evaporate and react with the plasma, and to adhere the resulting film-forming material to the target object.
The system includes a gas supply unit that supplies a gas containing the elements constituting the film from the electrode side toward the plasma guided to the electrode,
The aforementioned gas supply unit supplies the gas separately from the inert gas from a position adjacent to the electrode in the film deposition apparatus. The film deposition apparatus according to claim 1, wherein the gas supply unit supplies the gas from a position on the electrode side receiving the plasma, from the opposite side of the direction of propagation of the plasma received by the electrode. The film deposition apparatus according to claim 1 or 2, wherein the electrode has a channel for passing the gas, and the gas can be supplied from the outlet of the channel. The film deposition apparatus according to any one of claims 1 to 3, wherein the gas supply unit supplies the gas from a position radially away from the electrode by a distance of 1.5 times or less the diameter of the electrode. The film deposition apparatus according to any one of claims 1 to 4, wherein the gas supply unit supplies the gas from a position radially separated from the electrode by a distance of 70 mm or less. The electrode is provided with a cylindrical member that covers the electrode,
The film deposition apparatus according to any one of claims 1 to 5, wherein the gas supply unit supplies the gas from between the electrode and the cylindrical member. The film deposition apparatus according to any one of claims 1 to 6, wherein the plasma generation unit is a pressure gradient type plasma gun. The electrode further comprises an auxiliary electrode surrounding the aforementioned electrode,
The film deposition apparatus according to any one of claims 1 to 7, wherein the gas supply unit supplies the gas from the inner circumference side of the auxiliary electrode. The film deposition apparatus according to any one of claims 1 to 8, wherein the gas supply unit comprises a first supply unit and a second supply unit that supplies the gas at a position closer to the electrode than the first supply unit, and the amount of gas supplied by the second supply unit is greater than the amount of gas supplied by the first supply unit. A film formation method in which particles of a film-forming material are attached to an object using a film-forming apparatus to form a film,
The aforementioned film deposition apparatus is
A plasma generation unit that generates plasma,
The system includes an electrode positioned at a distance from the plasma generation unit, which holds the film-forming material during film formation and guides the plasma to the film-forming material, thereby causing the film-forming material to evaporate and react with the plasma, and to adhere the resulting film-forming material to the target object.
The aforementioned film formation method includes a gas supply step of supplying a gas containing the elements constituting the film from the electrode side toward the plasma guided to the electrode,
A film deposition method comprising supplying the gas separately from the inert gas from a position adjacent to the electrode in the gas supply step .