Film deposition apparatus and film deposition method

Abstract

To suppress a generation of malfunction caused by a gas remained in a gap formed in a film deposition gas supply part including a shower head.SOLUTION: A film deposition gas supply part composed of a shower head including multiple discharge hole and an upper side member for forming a diffusion space of a film deposition gas communicating with each discharge hole is provided at an upper part of a treatment container that accommodates a substrate and in which the vacuum atmosphere is produced. The film deposition gas supply part includes: an annular first seal member that surrounds the diffusion space in a plan view and adheres to the shower head and the upper side member; a second annular seal member that surrounds the first seal member in a plan view and adheres to the shower head and the upper side member. The film deposition gas supply part also includes a gas exhaust route formed such that an upper stream end is opened in a gap formed by the first seal member, the second seal member, the shower head, and the upper side member and a downstream end is opened in the treatment container.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present disclosure relates to a film forming apparatus and a film forming method. [Background Art]

[0002] In manufacturing a semiconductor device, as an apparatus for forming a film on a semiconductor wafer serving as a substrate (hereinafter referred to as a wafer), Patent Document 1 describes a configuration in which a raw material gas for film formation is supplied to a wafer arranged in a processing container through a discharge port of a shower head. The shower head is provided below a raw material gas diffusion chamber provided in an upper portion of the processing container. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Laid-Open No. 2020-132942 [Summary of Invention] [Problem to be Solved by the Invention]

[0004] The present disclosure provides a technique for suppressing the occurrence of defects caused by gas accumulated in a gap formed in a film forming gas supply unit including a shower head. [Means for Solving the Problem]

[0005] The film forming apparatus of the present disclosure includes: a processing container that accommodates a substrate and has an interior set to a vacuum atmosphere; a film forming gas supply unit including a shower head provided with a plurality of discharge holes for supplying a film forming gas for forming a film on the substrate, and an upper member that forms a diffusion space for the film forming gas communicating with each of the discharge holes and is provided above the shower head in the processing container; an annular first seal member that surrounds the diffusion space in a plan view and is in close contact with the shower head and the upper member; An annular second sealing member surrounds the first sealing member in a plan view and is in close contact with the shower head and the upper side member, A gas discharge passage is formed in the film-forming gas supply section such that its upstream end opens into the gap formed by the first sealing member, the second sealing member, the shower head, and the upper member, and its downstream end opens into the processing container. It is equipped with. [Effects of the Invention]

[0006] According to this disclosure, it is possible to suppress the occurrence of malfunctions caused by gas accumulating in gaps formed in the film-forming gas supply section, including the showerhead. [Brief explanation of the drawing]

[0007] [Figure 1] This is a longitudinal cross-sectional side view showing one embodiment of a film deposition apparatus equipped with a film deposition gas supply unit in the present disclosure. [Figure 2] This is a longitudinal cross-sectional side view showing the first example of a conventional film deposition gas supply unit. [Figure 3] This is a longitudinal cross-sectional side view showing a second example of a conventional film deposition gas supply unit. [Figure 4A] This is a longitudinal cross-sectional side view showing one embodiment of the film-forming gas supply unit of the present disclosure. [Figure 4B] This is a longitudinal cross-sectional side view showing an enlarged portion of the film deposition gas supply section. [Figure 5] This is a plan view showing a part of the film deposition gas supply section. [Figure 6A] This is a longitudinal cross-sectional side view showing the recess and connection path forming member provided in the film-forming gas supply section. [Figure 6B] A perspective view showing an example of a connecting path forming member. [Figure 7A] This is a longitudinal cross-sectional side view showing the operation of the film deposition gas supply unit. [Figure 7B] This is a longitudinal cross-sectional side view showing the operation of the film deposition gas supply unit. [Figure 8A] This is a longitudinal cross-sectional side view showing the operation of the film deposition gas supply unit. [Figure 8B] This is a longitudinal cross-sectional side view showing the operation of the film deposition gas supply unit. [Figure 9] This is a longitudinal cross-sectional side view showing another example of a film deposition gas supply unit in this disclosure. [Figure 10] This is a schematic plan view of the showerhead. [Modes for carrying out the invention]

[0008] <Overview of film deposition equipment and conventional configuration> This disclosure relates to a process in which a film deposition gas is supplied from a film deposition gas supply unit to a processing container in which the interior is a vacuum atmosphere, and a film deposition is made on a wafer, which is a substrate, stored inside the processing container, with a gas discharge passage provided in the film deposition gas supply unit. Prior to describing the film deposition gas supply unit of this disclosure, the configuration of a conventional film deposition gas supply unit will be described with reference to Figures 1 to 3. Figure 1 shows an example of the configuration of a film deposition apparatus 1 equipped with the film deposition gas supply unit 3 of this disclosure. However, since the conventional film deposition gas supply units 3A and 3B are also provided in the film deposition apparatus 1 in place of the film deposition gas supply unit 3, Figure 1 is also referred to. As shown in Figure 1, in the film deposition apparatus 1, the film deposition gas supply units 3 (3A, 3B) are provided on the upper side of the processing container 2.

[0009] Figure 2 shows a film-forming gas supply unit 3A of a first example of a conventional configuration. This film-forming gas supply unit 3A comprises a shower head 31 facing the wafer W and an upper member 32 provided above the shower head 31. Both the shower head 31 and the upper member 32 are made of metal. The shower head 31 has a plurality of discharge holes 311 formed therein, and the upper member 32 is configured to form a diffusion space 30 for the film-forming gas that communicates with each discharge hole 311 between itself and the shower head 31.

[0010] For example, the upper member 32 forms a diffusion space 30, and is composed of: a flow path forming member 33 provided with a film forming gas flow path 331; and a top plate member 34 provided above the flow path forming member 33 and functioning as a top plate of the processing container 2. The top plate member 34 is provided with a downwardly protruding protruding portion 35 on the outer side of the flow path forming member 33. The outer peripheral side of the upper surface of the shower head 31 is provided so as to be connected to the lower surface of the protruding portion 35, and the shower head 31 and the protruding portion 35 are joined by screws 36 at a plurality of locations in the circumferential direction. Thereby, the shower head 31 is supported by the upper member 32. The joint between the shower head 31 and the upper member 31 is located inside the processing container 2. Further, an annular first seal member 41 is provided so as to surround the diffusion space 30 in a plan view and be in close contact with the shower head 31 and the upper member 32 (the flow path forming member 33). That is, the first seal member 41 is provided so as to prevent gas from flowing between the outside of the film forming gas supply unit 3A in the processing container and the diffusion space 30 through the joint described above.

[0011] In such a film forming gas supply unit 3A, although the shower head 31 and the upper member 32 (the protruding portion 35) are joined by screws 36, minute gaps are formed in these joints. Therefore, during film forming processing, the film forming gas supplied into the processing container 2 may flow into the joint, form a film on the portion, and cause damage to the joint. This is because, since the joint is formed by joining metal members to each other with the screws 36, minute physical scratches are formed by the torque during screwing, and film formation on the joint may apply unintended stress to the scratched portion, thereby causing damage to the portion. For this reason, over time, deterioration of the joining state between the shower head 31 and the upper member 32 may cause concerns such as particle generation, or temperature change of the shower head 31 (which in turn leads to change in processing temperature between wafers W) due to change in heat conduction at the joint.

[0012] Therefore, as shown in FIG. 3 illustrating the film forming gas supply unit 3B of the second conventional example, an annular second seal member 42 is provided on the outside of the first seal member 41 so as to be in close contact with the shower head 31 and the upper member 32. More specifically, the second seal member 42 is provided between the projecting portion 35 forming the peripheral edge of the upper member 32 and the peripheral edge of the shower head 31. The second seal member 42 can suppress the wraparound of film forming gas to the joint between the shower head 31 and the upper member 32 inside the second seal member 42, thereby solving the problem in the film forming gas supply unit 3A.

[0013] However, after the manufacturing or maintenance of the film forming apparatus 1 is completed, the disassembled members are assembled in an atmospheric atmosphere to form the film forming gas supply unit 3B. After assembling the film forming gas supply unit 3B, air remains in the gap 37 between the upper member 32 and the top plate member 34, and the gap 38 between the first seal member 41 and the second seal member 42 at the joint of the shower head 31 and the upper member 32. Note that the gaps 37 and 38 communicate with each other, and a part of the gap 38 in the radial direction extends upward, which can be considered as forming the gap 37.

[0014] The film forming gas supply unit 3B with air remaining as such is attached to the processing container 2, and the inside of the processing container 2 is brought into a vacuum atmosphere for processing the wafer W. However, since the gaps 37 and 38 are sealed from the outside of the film forming gas supply unit 3B by the second seal member 42, it is difficult for air to be discharged from the gaps 37 and 38. Therefore, air remains in the gaps 37 and 38 even after the start of the film forming process, and there is a risk that even a small amount of air leaks through the second seal member 42 and is released into the processing container 2 during the film forming process. In this case, there is a concern that problems such as reaction products (by-products) between the air and the film forming gas mixing into the film on the wafer W may occur.

[0015] <Configuration of Film Forming Apparatus 1> Based on the above, the film deposition gas supply unit 3 of this disclosure is provided with a gas discharge passage 6 in order to solve the problems of the conventional film deposition gas supply units 3A and 3B. An embodiment of the film deposition apparatus 1 equipped with this film deposition gas supply unit 3 will be described with reference to Figures 1, 4 to 6. Among the components of the film deposition gas supply unit 3, the same components as those described in the film deposition gas supply units 3A and 3B will be indicated using the same reference numerals as those used in the description of the film deposition gas supply units 3A and 3B, and will be described in more detail.

[0016] The film deposition apparatus 1 includes a processing container 2 in which wafers W are stored and which is kept in a vacuum atmosphere. This processing container 2 is configured, for example, to have a roughly circular planar shape. On the side of the processing container 2, an inlet / outlet 22 for transferring wafers W to and from an external vacuum transfer chamber (not shown) is provided, which can be opened and closed by a gate valve 23. Hereafter, in Figure 1, the horizontal direction will be referred to as the X direction, the direction perpendicular to the plane of the paper as the Y direction, and the vertical direction as the Z direction. Above the loading / unloading port 22, an exhaust duct 24 with a rectangular cross-sectional shape is provided, stacked on top of the side walls 21 that constitute the main body of the processing container 2. The exhaust duct 24 has a slit-shaped opening 241 along the circumferential direction on its inner surface and an exhaust port 25 on its outer surface. An exhaust mechanism 26, consisting of a vacuum pump and a pressure regulating valve, is connected to the exhaust port 25 via an exhaust passage 261, and the inside of the processing container 2 is set to a vacuum atmosphere.

[0017] A mounting platform 5 on which the wafer W is placed is positioned inside the exhaust duct 24 within the processing container 2, and a heating unit 51 for heating the wafer W is embedded inside the platform. A lifting shaft 52 is provided in the center of the lower surface of the mounting base 5, extending vertically and penetrating the bottom surface of the processing container 2. The lower end of the lifting shaft 52 is connected to a lifting mechanism 53 outside the processing container 2. The lifting mechanism 53 comprises a lifting plate 531 to which the lower end of the lifting shaft 52 is connected, a cylinder rod 532, and a motor 533. The bottom surface of the processing container 2 and the lifting plate 531 are connected by a bellows 54.

[0018] Thus, the mounting platform 5 is configured to be airtightly able to move up and down between a processing position (shown in Figure 1) where film deposition is performed on the wafer W and a transfer position below this processing position where the wafer W is transferred via the loading / unloading port 22, by means of a lifting / lowering mechanism 53. Furthermore, below the mounting platform 5, a plurality of support pins 27 are provided, which are movable up and down by a lifting mechanism 271, to support and lift the wafer W from the bottom when the wafer W is being transferred.

[0019] <Film-forming gas supply unit 3> The ceiling of the processing container 2 is configured as a film-forming gas supply unit 3. As previously described, this film-forming gas supply unit 3 includes a shower head 31 and an upper member 32. The shower head 31, which is a horizontal plate-shaped member, is positioned to face the wafer W placed on the mounting table 5, and is configured in a circular shape in plan view, for example, with a diameter larger than that of the wafer W. In this shower head 31, a number of discharge holes 311 for supplying film-forming gas to the wafer W placed on the mounting table 5 are dispersed in the region facing the wafer W placement area on the mounting table 5 and are provided in the thickness direction of the shower head 31.

[0020] The upper member 32 is configured to form a diffusion space 30 for the film-forming gas that communicates with each discharge hole 311 between itself and the shower head 31. In this example, the diffusion space 30 is a flat, circular space in plan view. As previously described, the upper member 32 is composed of a flow path forming member 33 and a top plate member 34. The top plate member 34 is provided to span, for example, the upper surface of the flow path forming member 33 and the upper surface of the exhaust duct 24 and connect to them, and has an annular projection 35 that protrudes downward between the flow path forming member 33 and the exhaust duct 24. In other words, the flow path forming member 33 is provided surrounded by the projection 35. The flow path forming member 33 is a circular block with a recess formed on its lower surface, and this recess forms the diffusion space 30.

[0021] The outer circumference of the upper surface of the shower head 31 is positioned to contact the lower surface of the protrusion 35 of the upper member 32, and as shown in Figure 4A, the shower head 31 and the protrusion 35 are joined by screws 36. Although only one screw 36 is shown in Figure 4A, multiple screws 36 are provided at intervals in the circumferential direction of the shower head 31, and the shower head 31 is screwed in at multiple locations. In addition, a gap 37 is formed between the outer circumference of the flow path forming member 33 and the inner circumference of the protrusion 35.

[0022] As shown in Figures 4 and 5, an annular first sealing member 41 is provided between the shower head 31 and the upper member 32, surrounding the diffusion space 30 in a plan view and in close contact with the shower head 31 and the flow path forming member 33 of the upper member 32. An annular second sealing member 42 is also provided, surrounding the first sealing member 41 in a plan view and in close contact with the shower head 31 and the protruding portion 35 of the upper member 32. Furthermore, in this example, a third sealing member 43 is also provided between the flow path forming member 33 and the top plate member 34, on the outer circumference of the flow path forming member 33, in close contact with these members. This prevents the gas supplied from the gas introduction passage 341 (described later) from leaking between the flow path forming member 33 and the top plate member 34. In addition, a fourth sealing member 44 is provided around the screw 36 to ensure airtightness of the screw hole to the outside.

[0023] The first to fourth sealing members 41 to 44 are composed of elastic annular members, such as O-rings, and are made of resin, for example. In Figures 1 and 4A, the O-rings forming the sealing members 41 to 43 are depicted between members that are in close contact with each other. However, in reality, as illustrated in Figure 4B, a groove 45 is formed in one of the members that are in close contact with each other, and an O-ring 46 is placed in this groove 45. The restoring force of the O-ring 46 is used to airtightly seal the space between these members.

[0024] As shown in Figures 4A and 4B, the film-forming gas supply unit 3 is equipped with a gas discharge passage 6. This gas discharge passage 6 is formed such that its upstream end opens into a gap 38 formed by the first sealing member 41, the second sealing member 42, the shower head 31, and the upper member 32, and its downstream end opens into the processing container 2. The gap 38 is a minute gap formed at the joint between the shower head 31 and the protruding portion 35 of the upper member 32, and may also be referred to as the "joint gap 38". In this example, the gas discharge passage 6 is formed in the shower head 31, as shown in Figure 4B, and includes a downstream discharge passage 61 that forms the downstream side of the gas discharge passage 6, and an upstream discharge passage 62 that forms the upstream side. In the gas discharge passage 6, the side with the joint gap 38 is considered the upstream side, and the side toward which the gas is directed by the exhaust from the processing container 2 is considered the downstream side.

[0025] On the upper surface of the shower head 31, a recess 7 is formed that opens into the joint gap 38, and together with the connecting path forming member 8 described later, constitutes the upstream side of the gas discharge passage 6. More specifically, the recess 7 is provided on the periphery of the shower head 31 so as to face the protrusion 35 of the upper member 32, and is located in the region of the shower head 31 outside the region facing the wafer W. As will be described later, a film is formed in the recess 7 by the film-forming gas flowing back through the gas discharge passage 6, but the film is formed outside the region facing the wafer W. Therefore, even if the temperature distribution on the lower surface of the shower head 31 changes slightly due to this film formation, the effect of this change in temperature distribution on the in-plane temperature distribution of the wafer W is negligible or minimal, which is preferable. Furthermore, the recess 7 is provided locally in the circumferential direction of the shower head 3. Therefore, the location where the film is formed by the back-flowing film-forming gas can be kept small, and thus the effect on the in-plane temperature distribution of the wafer W described above can be suppressed more reliably, which is preferable.

[0026] As shown in Figures 4A, 4B, and 5, the recess 7 in this example is configured to be rectangular in both plan and side views, and is equipped with a horizontal bottom surface 71 and vertical side walls 72. For example, the downstream discharge passage 61 is formed such that its downstream end opens near the opening 241 of the exhaust duct 24 on the side of the shower head 31, extends along the lateral direction (X direction), then bends upward, and its upstream end opens to the bottom surface 71 of the recess 7.

[0027] A metal connecting passage forming member 8 is embedded inside the recess 7 so as to close the opening of the downstream discharge passage 61. This connecting passage forming member 8 forms a localized narrowing in the gas discharge passage 6 and also forms a connecting passage for connecting the downstream discharge passage 61 and the joint gap 38. As shown in Figures 4B, 5, and 6A, the connecting channel forming member 8 in this example is formed in a prism shape that is slightly smaller than the recess 7. As a result, when the connecting channel forming member 8 is embedded in the recess 7, the side wall 82 of the connecting channel forming member 8 separates from the side wall 72 of the recess 7, and the upstream discharge channel 62 is formed between the side walls 72, 82.

[0028] The bottom surface 81 of the connecting channel forming member 8 forms a connecting surface that contacts the bottom surface 71 of the recess 7, and this bottom surface 81 is provided with a minute groove 83 extending along the lateral direction (X direction). In this example, as shown in Figure 6A, the groove 83 has a triangular vertical cross-sectional shape, so that when the connecting channel forming member 8 is embedded in the recess 7, a flow path is formed between the groove 83 and the bottom surface 71 of the recess 7. The triangular vertical cross-sectional shape of the groove 83 is preferable because it reduces the conductance of the flow path, which can more reliably suppress the inflow of the film-forming gas into the joint gap 38, as described later, but this cross-sectional shape is arbitrary and may be, for example, square. The flow path formed by this groove 83 extends horizontally in the lateral direction (X direction), and is connected to the downstream discharge channel 61 at approximately the center of its length, with both ends of the flow path connected to the upstream discharge channel 62. Therefore, the flow path formed by the groove 83 functions as a connecting channel for connecting the downstream discharge channel 61 and the joint gap 38 via the upstream discharge channel 62.

[0029] The cross-sectional area of ​​the flow path formed by the groove 83 is smaller than the cross-sectional area of ​​the upstream discharge passage 62 and the cross-sectional area of ​​the downstream discharge passage 61, for example, it is formed to be 1 / 2 or less. Therefore, the flow path formed by the groove 83 is configured as a constricted section 63 that narrows the gas discharge passage 6 midway. The upstream discharge passage 62 is shaped like a rectangular frame in cross-section due to the side wall 82 of the connecting passage forming member 8 and the side wall 72 of the recess 7, so its cross-sectional area is the area of ​​the rectangular frame. The flow path diameter of the downstream discharge passage 61 is, for example, 1 to 3 mm, and the flow path diameter of the constricted section 63 is, for example, 0.1 to 0.5 mm. The cross-section of the flow path of the downstream discharge passage 61 is circular, but as described above, the cross-section of the flow path of the constricted section 63 (the cross-section of the groove 83) is triangular or square, not circular. The channel diameter of the constricted portion 63 referred to here is the channel diameter (diameter of the channel) if the cross-section of the triangular or square channel were transformed into a circular shape with the same area.

[0030] Thus, the gas discharge passage 6 is constructed by connecting the downstream discharge passage 61, the constricted section 63, and the upstream discharge passage 62. Therefore, when viewing the gas discharge passage 6 from the downstream end, the upstream end of the downstream discharge passage 61 is connected to the constricted section 63, causing the flow path to narrow and bend laterally, and then the flow path bends vertically to become the upstream discharge passage 62, which is connected to the joint gap 38. Furthermore, regarding the length L1 in the X direction of the connecting channel forming member 8 (length of the constricted portion 63), if it is too long, it may hinder the discharge of air from the gaps 37 and 38, which will be described later. If it is too short, it may cause the film-forming gas to flow into the gaps 37 and 38, which will be described later. From this viewpoint, it is preferable that the length L1 be, for example, 1 mm to 100 mm. Also, the length L2 in the Y direction of the connecting channel forming member 8 is, for example, 100 mm or less, and the length L3 in the Z direction is, for example, 20 mm or less. Note that the flow path diameter and the size of the connecting channel forming member 8 mentioned here are the sizes when the film-forming gas supply unit 3 is placed in an environment at room temperature (15°C to 30°C). Also, although the upper surface of the connecting channel forming member 8 is shown to be in contact with the protrusion 35 of the upper side member 32 in each figure, it is not necessary for them to be in contact in this way, and they may be separated.

[0031] Returning to Figure 1 and continuing the explanation, the upper member 32 has a heating section 39 positioned between the flow path forming member 33 and the top plate member 34, facing the diffusion space 30. Furthermore, a gas supply pipe 91 for introducing film-forming gas is connected to the upper member 32, and a gas introduction passage 341 is formed in the top plate member 34. In addition, a gas flow path 331 is formed in the flow path forming member 33, with the upstream side connected to the gas introduction passage 341 and the downstream side branching off and connected to the diffusion space 30. The film-forming gas supplied from the gas supply system 9 to the film-forming gas supply unit 3 via the gas supply pipe 91 reaches the diffusion space 30 via the gas introduction passage 341 and the gas flow path 331, and is discharged from each discharge hole 311 toward the mounting base 5.

[0032] Figure 1 shows a gas supply system 9, which collectively consists of multiple gas supply sources 92 and multiple gas supply lines 93. The gas supply system 9 will be explained using the case of depositing a titanium nitride (TiN) film on a wafer W as an example. For example, the film deposition apparatus 1 is configured to deposit a TiN film by ALD (Atomic Layer Deposition) by alternately supplying two types of gases as deposition gases to the processing container 2. As deposition gases, a raw material gas containing titanium (Ti), such as titanium tetrachloride (TiCl4) gas, and a reaction gas containing nitrogen (N), such as ammonia (NH3) gas, can be used.

[0033] The gas supply source 92 includes a raw material gas supply source and a reaction gas supply source, each connected to the film-forming gas supply unit 3 via a gas supply passage. Each gas supply passage is equipped with a flow control unit 93, which includes valves for cutting off the gas supply and flow rate adjustment units for adjusting the gas supply amount, as well as a gas storage tank (not shown). The TiCl4 gas and NH3 gas are, for example, temporarily stored in the storage tank, pressurized to a predetermined pressure, and then supplied into the processing container 2. Furthermore, the gas supply source 92 also includes a supply source for displacement gas and a supply source for cleaning gas, and each supply source is connected to the film deposition gas supply unit 3 via a gas supply path. As the displacement gas, an inert gas such as nitrogen gas (N2 gas) or argon gas (Ar gas) can be used, and as the cleaning gas, for example, NF3 gas can be used.

[0034] As shown in Figure 1, the film deposition apparatus 1 includes a control unit 100 that controls the operation of each part that constitutes the film deposition apparatus 1. This control unit 100 consists of a computer, for example, a CPU (not shown) and a memory unit, and the memory unit stores a program containing a set of steps (instructions) for the control necessary to perform the deposition of a TiN film, which will be described later. The program is stored on a storage medium such as a hard disk, compact disk, magnetic optical disk, memory card, or non-volatile memory, and installed from there onto the computer.

[0035] <Deposition of TiN films in a film deposition apparatus> Next, we will explain how to perform a TiN film deposition process using the film deposition apparatus 1 equipped with the configuration described above, using the case where the film deposition process is resumed after maintenance of the film deposition apparatus 1 is completed as an example. As previously described, the maintenance includes the process of disassembling and reassembling the film-forming gas supply unit 3 in an atmospheric environment. During this maintenance, the film-forming gas supply unit 3 is exposed to air in the gap 37, the joint gap 38 formed by the first sealing member 41, the second sealing member 42, the shower head 31 and the upper member 32, and the gas discharge passage 6.

[0036] Before performing the film deposition process, the inside of the processing container 2 is reduced to a vacuum to remove any foreign matter such as residual water. In parallel with this reduction in pressure, the heating unit 39 of the film deposition gas supply unit 3 is raised to a predetermined set temperature, for example, 170°C, and the heating unit 51 of the mounting table 4 is also raised to a predetermined set temperature, for example, 400°C, so that the wafer W can be received into the processing container 2 and processed.

[0037] As the temperature of the film-forming gas supply unit 3 rises due to the heat conduction from the heating unit 39 and the radiant heat from the heating unit 51 caused by the heating unit 39 and 51 to heat up, the temperature of the air in the gaps 37 and 38 also rises, and the diffusivity of the air increases. Since the inside of the processing container 2 is being exhausted, the air with increased diffusivity passes through the narrowed section 63 of the gas discharge passage 6, as shown by the dashed line in Figure 7A, and flows out to the outside of the shower head 3, and is exhausted towards the exhaust duct 24.

[0038] When the heating section 39 of the film deposition gas supply unit 3 and the heating section 51 of the mounting table 4 reach their respective set temperatures, the pressure inside the processing container 2 is set to a predetermined vacuum pressure, and the mounting table 5 has been lowered to the transfer position, the wafer W is placed inside the processing container 2 through the cooperative operation of an external transport mechanism (not shown) and the support pins 27. Then, the wafer W is placed on the mounting table 5, which has been heated to the film deposition temperature (set temperature) by the heating section 51, and the mounting table 5 is moved to the processing position. Next, a process is carried out in which a film-forming gas is supplied from the film-forming gas supply unit 3 to the surface of the wafer W, which has been heated to the film-forming temperature, in order to form a film. In this process, the supply of film-forming gases (TiCl4 gas, NH3 gas) and gas for replacing the atmosphere in the processing container 2 (N2 gas) is repeated in the order of TiCl4 gas → N2 gas → NH3 gas → N2 gas. At this time, the supply time of the film-forming gases, TiCl4 gas and NH3 gas, is, for example, 5 seconds or less.

[0039] As a result, the two types of film-forming gases adsorbed on the wafer W react with each other to form TiN molecular layers, and these molecular layers are stacked to form a titanium nitride film (TiN film). In this way, the above-mentioned supply cycle of deposition gas and displacement gas is repeated several tens to several hundreds of times to deposit a TiN film of the desired thickness. After this, the gas supply is stopped, the mounting stage 3 is lowered to the transfer position, and the gate valve 23 is opened to remove the wafer W.

[0040] During the film formation process, the downstream end of the downstream discharge channel 61 is open inside the processing container 2, so the film formation gas may flow back into the downstream discharge channel 61 and enter the container. However, the upstream end of the downstream discharge channel 61 is connected to the constricted section 63. Looking at the connection between the downstream discharge channel 61 and the constricted section (connecting channel) 63, the flow direction of the downstream discharge channel 61 and the flow direction of the constricted section 63 are different, and this connection section has a bent flow path. Thus, within the gas discharge channel 6, the flow path narrows at the constricted section 63, and the direction of gas flow also changes, making it difficult for the film formation gas to flow through the constricted section 63.

[0041] Therefore, as shown by the dashed line in Figure 7B, the flow of the film-forming gas is suppressed upstream of the constricted portion 63 formed by the connecting passage forming member 8, making it difficult for the film-forming gas to reach the upstream discharge passage 62, thus suppressing the intrusion of the film-forming gas into the upstream discharge passage 62. In particular, in the ALD method, the supply time of the film-forming gas, TiCl4 gas or NH3 gas, is extremely short, so the film-forming gas remains in the constricted area 63, further preventing the film-forming gas from entering upstream of the constricted area 63.

[0042] Thus, the film-forming gas accumulates in the constricted section 63, and as shown in Figure 8A, a film 90 is deposited in the constricted section 63, but film formation is limited to this region. Furthermore, because the flow path becomes even more narrowed in the constricted section 63 due to film formation, the intrusion of the film-forming gas upstream of the constricted section 63 is further suppressed. For this reason, the film-forming gas does not reach the junction between the shower head 31 and the upstream discharge channel 62, and film formation at the junction can be suppressed.

[0043] In this manner, after depositing a TiN film onto multiple wafers W in the film deposition apparatus 1, cleaning is performed. This cleaning is carried out, for example, by evacuating the inside of the processing container 2 through the exhaust duct 24 using the exhaust mechanism 26, heating it with heating units 39 and 51, and supplying NF3 gas, which is a cleaning gas, from the gas supply system 9, as shown by the solid line in Figure 8A.

[0044] The cleaning gas is supplied into the processing container 2 via the film-forming gas supply unit 3, and comes into contact with the film attached to the inside of the processing container 2, causing the film to peel off from the processing container 2. The cleaning gas containing the peeled film is discharged to the outside via the exhaust duct 24 as the exhaust mechanism 26 exhausts the gas. At this time, as shown in Figure 8A, the cleaning gas also enters the gas discharge passage 6 of the film deposition gas supply unit 3 and comes into contact with the film 90 attached to the constricted portion 63. As a result, the film 90 is peeled off from the constricted portion 63, and as shown by the thick line in Figure 8B, the cleaning gas containing the peeled film 90 is discharged and removed through the gas discharge passage 6.

[0045] According to the above embodiment, since the film-forming gas supply unit 3 is provided with a gas discharge passage 6, the gaps 37 and 38 formed by the first sealing member 41, the second sealing member 42, the shower head 31, and the upstream discharge passage 62 can be exhausted through the gas discharge passage 6. As a result, as described above, even if air remains in the film deposition gas supply unit 3, the air can be discharged before the film deposition process, thereby suppressing the reaction between the air and the film deposition gas during the film deposition process. From another perspective, this shortens the vacuuming time required to discharge the air before starting the film deposition process, thus increasing the processing efficiency of the device.

[0046] Furthermore, by providing a localized narrowing section 63 in the gas discharge passage 6, the intrusion of film-forming gas into the joint between the shower head 31 and the upper member 32 can be suppressed, preventing film formation at the joint. As a result, the occurrence of scratches at the joint, which had been a problem due to film formation at the joint, can be suppressed, reducing the risk of particles, and the heat conduction at the joint is improved, thereby suppressing temperature changes of the shower head 31 with each wafer W processing (and consequently, temperature changes between wafers W). In addition, as explained in Figure 8A, in the film-forming gas supply unit 3, film formation is performed at the constricted portion 63, that is, at the joint between the shower head 31 and the connecting passage forming member 8. However, compared to the film-forming gas supply unit 3A explained in Figure 2, the area where film formation is performed is kept smaller. Therefore, the risk of particle generation and temperature changes of the shower head 31 are suppressed.

[0047] Furthermore, in the film-forming gas supply unit 3A, if the upper member 32 deteriorates significantly due to film formation at the joint between the shower head 31 and the upper member 32, the upper member 32 will need to be replaced. However, since the upper member 32 forms the top plate of the processing container 2, it is relatively large. Therefore, the effort and cost of replacement will be high. On the other hand, in the film-forming gas supply unit 3, even if the connecting path forming member 8 deteriorates significantly due to film formation at the joint between the shower head 31 and the connecting path forming member 8, it is sufficient to replace the relatively small connecting path forming member 8, resulting in a low-cost and simple operation. In other words, the configuration of the film-forming gas supply unit 3 is advantageous in terms of equipment maintenance. Furthermore, in the above example, the constricted portion 63 is formed by embedding the connecting path forming member 8, which has a groove 83 formed in it, into the recess 7, so the constricted portion 63 can be formed by a simple method.

[0048] In the present invention, the film deposition apparatus may be configured such that only a gas discharge passage 60 is provided in the film deposition gas supply unit 3C, as shown in Figure 9. The gas discharge passage 60 is formed such that its upstream end opens into the gap 38 formed by the first sealing member 41, the second sealing member 42, the shower head 31, and the upper side member 32, and its downstream end opens into the processing container 2. In this example, the gas discharge passage 60 is formed with a flow path diameter of, for example, 1 to 5 mm. The other configurations of the film deposition gas supply unit 3C are the same as those of the film deposition gas supply unit 3.

[0049] In this configuration, although the gas discharge passage 60 does not have a constricted section 63, the gap 38 can be exhausted through the gas discharge passage 60. Therefore, air that enters the film-forming gas supply section 3C during the manufacturing or maintenance of the device can be exhausted and removed through the gas discharge passage 60. However, because the constricted portion 63 is not provided, there is a risk that the film-forming gas may flow into the gaps 37 and 38. The configuration of the film-forming gas supply unit 3, as described in Figure 4, is more preferable in that it can more reliably suppress such inflow.

[0050] By the way, Figure 10 is a cross-sectional plan view of the shower head 31. The gas discharge passage 60 is preferably formed to be relatively long in order to suppress the inflow of film-forming gas into the gaps 37 and 38. On the other hand, in order to avoid formation in the region where the discharge holes 311 in the shower head 31 are formed (the region facing the wafer W), the gas discharge passage 60 is formed to extend in a direction inclined with respect to the straight line L0 connecting point P1, which is its downstream end in a plan view, and the center P0 of the shower head 31, as shown in this figure. The downstream discharge passage 61 of the film-forming gas supply unit 3 can also be formed to extend in a direction inclined with respect to the straight line L0, similar to the gas discharge passage 60 shown in Figure 10.

[0051] In the first embodiment of the film-forming gas supply unit 3, when forming the constricted portion 63 by the combination of the recess 7 and the connecting path forming member 8, a minute groove may be formed on the bottom surface 71 of the recess 7 instead of the bottom surface 81 of the connecting path forming member 8. Furthermore, the positional relationship between the recess 7, the gas discharge passage 6, and the connecting passage forming member 8 is not limited to the example described above. For example, the upstream end of the downstream discharge passage 61 of the gas discharge passage 6 may open into the side wall of the recess 7. In this case, the connecting passage forming member 8 is embedded in the recess 7 in contact with the side wall of the recess 7 and closes the opening of the downstream discharge passage, and a minute groove is formed vertically on the surface of the connecting passage forming member 8 that is in contact with the side wall of the recess 7. In this example, the constricted portion 63 extends vertically, with one end opening into the gap of the joint, and one end of the constricted portion 63 forms the upstream end of the gas discharge passage 6. Alternatively, the constricted portion may be provided by forming a groove in the side wall of the recess 7 instead of the connecting passage forming member 8.

[0052] Furthermore, instead of providing the gas discharge passage 6 in the shower head 31, it may be provided in the upper member 32. In this case, the recess 7 is provided on the lower surface of the upper member 32, opening into the gap between the shower head and the upper member 32. The upstream end of the downstream discharge passage 61 opens into the recess 7, and a connecting passage forming member 8 is embedded to close this opening. A minute groove is formed in either the connecting passage forming member 8 or the recess 7, thereby forming a constricted portion 63.

[0053] The shape of the recess 7 and the connecting passage forming member 8 provided on either the shower head 31 or the upper member 32 is not limited to the configuration described above. Furthermore, the constricted portion 63 provided in the gas discharge passage 6 may be formed by locally narrowing the flow path itself that constitutes the gas discharge passage 63. In other words, assuming that the gas discharge passage 60 is formed as shown in Figure 9, the flow path diameter of a part of the gas discharge passage 60 may be smaller than the flow path diameter of other parts. Furthermore, the film deposition process of this disclosure is applicable to a film deposition process in which a wafer is placed in a processing container set to a vacuum atmosphere, and a film deposition gas is supplied to the wafer from a film deposition gas supply unit to deposit a film. Therefore, the film deposition process is not limited to ALD, but may also be CVD (Chemical Vapor Deposition). When applied to ALD, the discharge of the film deposition gas becomes intermittent, and as illustrated, the time of each discharge is relatively short. Therefore, the inflow of film deposition gas from the constricted portion 63 into the gaps 37 and 38 is suppressed more reliably.

[0054] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The above embodiments may be omitted, substituted, modified, or combined in various ways without departing from the scope and spirit of the appended claims.

[0055] [Evaluation Test] The evaluation tests conducted in relation to the technology disclosed herein will now be described. These evaluation tests were performed by depositing TiN films onto multiple wafers using the film deposition apparatus 1 shown in Figure 1, followed by cleaning, and then disassembling the film deposition gas supply unit 3 and visually inspecting the condition of the shower head 31 and the upper member 32. The film deposition process began after maintenance of the film deposition apparatus 1, followed by a 6-hour process of exhausting the remaining air from the film deposition gas supply unit 3. The air exhaust process after maintenance, the TiN film deposition process, and cleaning were carried out as described above.

[0056] Furthermore, evaluation tests were also conducted in the same manner when the film deposition gas supply unit 3 (Example 1) was replaced with the film deposition gas supply unit 3C (Example 2) shown in Figure 9, the conventional film deposition gas supply unit 3A (Comparative Example 1) shown in Figure 2, and the conventional film deposition gas supply unit 3B (Comparative Example 2) shown in Figure 3. In the film deposition gas supply unit 3C of Example 2, the gas discharge passage 60 was formed so that the flow path diameter was 1 mm and the length of the flow path from the downstream end to the point where it bends upward (i.e., the length of the part that extends laterally) was 70 mm. In addition, the film deposition gas supply unit 3 of Example 1 has a configuration in which a recess 7 and a connecting passage forming member 8 are provided at the joint between the shower head 31 and the upper side member 32 in the gas discharge passage 60 of the film deposition gas supply unit 3C, and the flow path diameter of the narrowed portion 63 is 0.1 mm. In this Example 1 as well, the length of the flow path from the downstream end of the gas discharge passage 60 to the point where it bends upward is 70 mm, the same as in Example 2.

[0057] These results will be explained. In Comparative Example 1, in the film-forming gas supply unit 3A, residue remained in the entire area forming the joint with the upper side member 32 on the back surface (top surface) of the shower head 31, and it was confirmed that the joint had deteriorated due to scratches and other damage compared to before the film-forming process. In this film-forming gas supply unit 3A, it is thought that the film-forming gas flowed into the joint and formed a film over the entire joint on the shower head 31. Furthermore, it is presumed that even after cleaning, the gas did not easily flow into the joint, resulting in the film-forming residue adhering to it.

[0058] Furthermore, in Comparative Example 2, no residue was observed on the back surface of the shower head 31 in the film-forming gas supply unit 3B. This confirmed that the provision of the second sealing member 42 suppressed the leakage of film-forming gas into the joint between the shower head 31 and the upper member 32. However, a black film was observed adhering to the area around the screw 36 where the fourth sealing member 44 had been installed. It is presumed that this was caused by the atmosphere remaining in the film-forming gas supply unit 3B reacting with the fourth sealing member 44 and altering its properties.

[0059] Next, in the film-forming gas supply unit 3C of Example 2, no film-forming residue was observed on the back surface of the shower head 31, but a small amount of residue was found near the upstream end of the gas discharge passage 60 that opens into the gap 38. Since this residue is visually different from the black film in Comparative Example 2, it is presumed that the film-forming gas entered the gas discharge passage 60 and formed a film. However, since the amount of residue observed was minute, it was found that the configuration of Example 2 is also effective compared to the conventional configuration in that it discharges the air remaining in the film-forming gas supply section 3C and suppresses film formation at the joint between the shower head 31 and the upper member 32.

[0060] Furthermore, in the film-forming gas supply unit 3 of Example 1, no film-forming residue was visually observed on the back surface of the shower head 31, and no deterioration such as scratches was observed at the joint between the shower head 31 and the upper member 32 compared to before the film-forming process. This confirmed that in the film-forming gas supply unit 3 of Example 1, residual air is exhausted, the reaction between the air and the film-forming gas is suppressed, and the leakage of the film-forming gas is suppressed. [Explanation of Symbols]

[0061] W Semiconductor wafer 1 Film deposition equipment 2 Processing container 3. Film-forming gas supply unit 30 Diffusion space 31 Shower head 311 Discharge hole 32 Upper side member 39 gaps 41 First sealing member 42 Second sealing member 6. Gas discharge channel

Claims

1. A processing container that houses the circuit board and has a vacuum atmosphere inside, A film-forming gas supply unit comprising: a shower head having a plurality of discharge holes for supplying a film-forming gas for forming a film on the substrate; and an upper member provided above the shower head in the processing container, which forms a diffusion space for the film-forming gas communicating with each of the discharge holes; An annular first sealing member surrounds the diffusion space in a plan view and is in close contact with the shower head and the upper side member, An annular second sealing member surrounds the first sealing member in a plan view and is in close contact with the shower head and the upper side member, A gas discharge passage is formed in the film-forming gas supply section such that its upstream end opens into the gap formed by the first sealing member, the second sealing member, the shower head, and the upper member, and its downstream end opens into the processing container. A film deposition apparatus equipped with the following features.

2. The film deposition apparatus according to claim 1, wherein the gas discharge passage comprises a localized constricted portion.

3. A recess opening into the gap is provided on either the upper surface of the shower head or the lower surface of the upper member. The recess has an opening at the upstream end of the downstream discharge passage that forms the downstream side of the gas discharge passage. The film-forming apparatus according to claim 2, further comprising a connecting passage forming member which is embedded in the recess so as to close the opening of the downstream discharge passage and which forms a connecting passage for connecting the downstream discharge passage and the gap as the constricted portion.

4. The upstream end of the downstream discharge channel opens to the bottom surface of the recess, The connecting passage forming member is separated from the side wall of the recess and forms an upstream discharge passage, which is the upstream side of the gas discharge passage, between itself and the side wall. The film forming apparatus according to claim 3, wherein the connecting passage forming member comprises a connecting surface in contact with the bottom surface of the recess, and a groove formed on the connecting surface so as to connect the downstream discharge passage and the upstream discharge passage to form the connecting passage.

5. The film-forming apparatus according to claim 3, wherein the recess and the gas discharge passage are provided in the shower head.

6. A process of placing the substrate in a processing container with a vacuum atmosphere inside, A film-forming process is carried out by supplying a film-forming gas to the substrate using a film-forming gas supply unit comprising a shower head having multiple discharge holes, and an upper member provided above the shower head in the processing container, which forms a diffusion space for the film-forming gas communicating with each of the discharge holes, A step of exhausting the gap through a gas discharge passage formed in the film-forming gas supply section such that the upstream end opens into the gap formed by the shower head and the upper member and the downstream end opens into the processing container, an annular first sealing member that surrounds the diffusion space in a plan view and is in close contact with the shower head and the upper member, an annular second sealing member that surrounds the first sealing member in a plan view and is in close contact with the shower head and the upper member, and the gap is exhausted through a gas discharge passage formed in the film-forming gas supply section. A film formation method comprising the following:

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