Film forming apparatus and film forming method

Abstract

In a film forming apparatus, a film forming gas supply unit including a shower head having a plurality of ejection holes and an upper member forming a diffusion space of a film forming gas communicating with each ejection hole is provided in an upper portion of a processing container that holds a substrate and has a vacuum atmosphere inside. The film-forming gas supply unit is provided with: an annular first sealing member that is in close contact with the shower head and the upper member and surrounds the diffusion space in plan view; and an annular second sealing member that is in close contact with the shower head and the upper member and surrounds the first sealing member in a plan view, and the film-forming gas supply unit is provided with a gas discharge path through which the film-forming gas is discharged. The gas discharge path is formed such that the upstream end opens toward a gap formed by the first sealing member, the second sealing member, the shower head, and the upper member, and the downstream end opens toward the inside of the processing container.

Description

Technical Field

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

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

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-132942 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The present disclosure provides a method for suppressing an adverse situation caused by gas accumulated in a gap formed in a film forming gas supply unit including a shower head.

[0008] Means for Solving the Problems

[0009] The film forming apparatus of the present disclosure includes:

[0010] A processing container that stores a substrate, and the inside of the processing container is set to a vacuum atmosphere;

[0011] A film forming gas supply unit including a shower head and an upper side member, the shower head having a plurality of discharge holes for supplying a film forming gas for forming a film on the substrate, and the upper side member being disposed above the shower head in the processing container to form a diffusion space for the film forming gas communicating with each of the discharge holes;

[0012] A ring-shaped first sealing member that is in close contact with the shower head and the upper side member and surrounds the diffusion space in a plan view;

[0013] A ring-shaped second sealing member that is in close contact with the shower head and the upper side member and surrounds the first sealing member in a plan view; and

[0014] A gas discharge path formed in the film forming gas supply unit such that an upstream end opens to a gap formed by the first sealing member, the second sealing member, the shower head, and the upper side member and a downstream end opens into the processing container.

[0015] Effects of the Invention

[0016] According to the present disclosure, it is possible to suppress an adverse situation caused by gas accumulated in a gap formed in a film-forming gas supply unit including a shower head. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. 1 is a longitudinal sectional side view showing an embodiment of a film-forming apparatus including a film-forming gas supply unit of the present disclosure.

[0018] Figure 2 FIG. 2 is a longitudinal sectional side view showing a first example of a conventional film-forming gas supply unit.

[0019] Figure 3 FIG. 3 is a longitudinal sectional side view showing a second example of a conventional film-forming gas supply unit.

[0020] Figure 4A FIG. 4 is a longitudinal sectional side view showing an embodiment of a film-forming gas supply unit of the present disclosure.

[0021] Figure 4B FIG. 5 is a longitudinal sectional side view showing a part of the film-forming gas supply unit in an enlarged manner.

[0022] Figure 5 FIG. 6 is a top view showing a part of the film-forming gas supply unit.

[0023] Figure 6A FIG. 7 is a longitudinal sectional side view showing a concave portion and a connection path forming member provided in the film-forming gas supply unit.

[0024] Figure 6B FIG. 8 is a perspective view showing an example of the connection path forming member.

[0025] Figure 7A FIG. 9 is a longitudinal sectional side view showing the operation of the film-forming gas supply unit.

[0026] Figure 7B FIG. 10 is a longitudinal sectional side view showing the operation of the film-forming gas supply unit.

[0027] Figure 8A FIG. 11 is a longitudinal sectional side view showing the operation of the film-forming gas supply unit.

[0028] Figure 8B FIG. 12 is a longitudinal sectional side view showing the operation of the film-forming gas supply unit.

[0029] Figure 9 FIG. 13 is a longitudinal sectional side view showing another example of a film-forming gas supply unit of the present disclosure.

[0030] Figure 10 FIG. 14 is a schematic top view of a shower head. DETAILED DESCRIPTION

[0031] <SUMMARY AND EXISTING STRUCTURE OF THE FILM-FORMING APPARATUS>

[0032] In the present disclosure, when a film-forming gas is supplied from a film-forming gas supply unit to a processing chamber whose interior is set to a vacuum atmosphere to form a film on a wafer serving as a substrate stored in the processing chamber, a gas discharge path is provided in the film-forming gas supply unit.

[0033] Before describing the film-forming gas supply unit of the present disclosure, refer to Figures 1 - 3 to describe the structure of a conventional film-forming gas supply unit. Figure 1 A structural example of a film-forming apparatus 1 including the film-forming gas supply unit 3 of the present disclosure is shown. However, instead of the film-forming gas supply unit 3, conventional film-forming gas supply units 3A and 3B may be provided in the film-forming apparatus 1. Therefore, also refer to Figure 1 . As Figure 1 shown, in the film-forming apparatus 1, the film-forming gas supply unit 3 (3A, 3B) is provided on the upper side of the processing chamber 2.

[0034] Figure 2 The film-forming gas supply unit 3A of the first example of the conventional structure is shown. The film-forming gas supply unit 3A includes a shower head 31 facing the wafer W and an upper-side member 32 provided above the shower head 31. These shower head 31 and upper-side member 32 are made of metal. A plurality of ejection holes 311 are formed in the shower head 31, and the upper-side member 32 is configured to form a diffusion space 30 for the film-forming gas communicating with each ejection hole 311 between the upper-side member 32 and the shower head 31.

[0035] For example, the upper-side member 32 includes: a flow path forming member 33 that forms the diffusion space 30 and has a flow path 331 for the film-forming gas; and a top plate member 34 that is provided above the flow path forming member 33 and functions as a top plate of the processing chamber 2. The top plate member 34 has a protruding portion 35 protruding downward 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 set 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 a threaded member 36 at a plurality of circumferential positions. Thereby, the shower head 31 is supported by the upper-side member 32. The joining portion of the shower head 31 and the upper-side member 31 is located inside the processing chamber 2. In addition, a ring-shaped first sealing member 41 is provided so as to be in close contact with the shower head 31 and the upper-side member 32 (flow path forming member 33) and surround the diffusion space 30 in a plan view. That is, the first sealing member 41 is provided to prevent gas from flowing between the outside of the film-forming gas supply unit 3A in the processing chamber and the diffusion space 30 via the above-described joining portion.

[0036] In such a film-forming gas supply unit 3A, the showerhead 31 and the upper-side member 32 (projection 35) are joined together by a threaded member 36, but a minute gap is formed at their joint portion. Therefore, during the film-forming process, the film-forming gas supplied into the processing container 2 may bypass to the joint portion and form a film at this portion, thereby causing damage to the joint portion. This is because the joint portion joins metal members to each other by the threaded member 36, and thus minute scars are physically formed due to the torque during the threaded fixing. Since a film is formed at the joint portion, an unintended stress is applied to the portion where the scars are formed, and thus this portion may sometimes be damaged. Therefore, over time, the joining state between the showerhead 31 and the upper-side member 32 deteriorates, and thus particles may be generated, and the temperature of the showerhead 31 may change (and further cause a change in the processing temperature between the wafers W) due to a change in the heat conduction at the joint portion.

[0037] Therefore, in Figure 3 , as shown in the film-forming gas supply unit 3B of the second example of the conventional structure, an annular second seal member 42 is provided outside the first seal member 41 so as to be in close contact with the showerhead 31 and the upper-side member 32. More specifically, the second seal member 42 is provided between the projection 35 forming the peripheral portion of the upper-side member 32 and the peripheral portion of the showerhead 31. By this second seal member 42, it is possible to suppress the film-forming gas from bypassing to the joint portion between the showerhead 31 and the upper-side member 32 at a position inside the second seal member 42, and thus the problems in the film-forming gas supply unit 3A can be solved.

[0038] However, during the manufacture of the film-forming apparatus 1 or after the maintenance is completed, the film-forming gas supply unit 3B is formed by assembling the decomposed members in an atmospheric atmosphere. After the assembly of the film-forming gas supply unit 3B, in the film-forming gas supply unit 3B, air remains in the gap 37 between the upper-side member 32 and the top plate member 34 and in the gap 38 between the first seal member 41 and the second seal member 42 at the joint portion between the showerhead 31 and the upper-side member 32. In addition, the gaps 37 and 38 communicate with each other, and it can be considered that a part of the gap 38 extends upward in the radial direction to form the gap 37.

[0039] The film-forming gas supply section 3B that retains the atmosphere is installed in the processing container 2, and the inside of the processing container 2 is set to a vacuum atmosphere to process the wafer W. However, since the gaps 37 and 38 are sealed from the outside of the film-forming gas supply section 3B by the second sealing member 42, it is difficult for the atmosphere to escape from the gaps 37 and 38. Therefore, the atmosphere remains in the gaps 37 and 38 even after the film-forming process starts, and a small amount may leak into the second sealing member 42 and be discharged into the processing container 2 during this film-forming process. In this case, there may be a problem such that reaction products (by-products) of the atmosphere and the film-forming gas are mixed into the film of the wafer W.

[0040] <Structure of the film-forming apparatus 1>

[0041] Based on the above, in the film-forming gas supply section 3 of the present disclosure, a gas discharge path 6 is provided in the film-forming gas supply section 3 to solve the problems in the conventional film-forming gas supply sections 3A and 3B. Refer to Figure 1 、 Figure 4A FIGS. 10 to 6 to describe an embodiment of the film-forming apparatus 1 including the film-forming gas supply section 3. In addition, for the components of the film-forming gas supply section 3 that are the same as the components described for the film-forming gas supply sections 3A and 3B, the same reference numerals as those used when describing the film-forming gas supply sections 3A and 3B are used, and they are described in more detail.

[0042] The film-forming apparatus 1 includes a processing container 2 that stores the wafer W and has a vacuum atmosphere inside. The planar shape of the processing container 2 is configured to be substantially circular, for example. An inlet / outlet 22 for transferring the wafer W to / from an unillustrated vacuum transfer chamber outside is provided on the side surface of the processing container 2 so as to be freely opened and closed by a gate valve 23. Hereinafter, Figure 1 the X direction is set to the horizontal direction, the Y direction is set to the direction perpendicular to the paper surface, and the Z direction is set to the vertical direction for description.

[0043] An exhaust pipe 24 having a square cross-sectional shape is provided above the inlet / outlet 22 in a manner of being stacked on the side wall 21 of the main body of the processing container 2. A slit-shaped opening 241 is formed on the inner peripheral surface of the exhaust pipe 24 along the circumferential direction, and an exhaust port 25 is formed on the outer wall surface of the exhaust pipe 24. The exhaust port 25 is connected to an exhaust mechanism 26 including a vacuum pump, a pressure regulating valve, etc. via an exhaust path 261 to set the inside of the processing container 2 to a vacuum atmosphere.

[0044] A mounting stage 5 for mounting the wafer W is disposed at a position inside the exhaust pipe 24 in the processing container 2, and a heating unit 51 for heating the wafer W is embedded inside the mounting stage 5.

[0045] At the center of the lower surface of the mounting stage 5, a lifting shaft 52 is provided which penetrates the bottom surface of the processing container 2 and extends in the vertical direction. The lower end of the lifting shaft 52 is connected to a lifting mechanism 53 outside the processing container 2. The lifting mechanism 53 includes a lifting plate 531, a cylinder rod 532, and a motor 533 connected to the lower end of the lifting shaft 52. The bottom surface of the processing container 2 and the lifting plate 531 are connected by a bellows 54.

[0046] In this way, the mounting stage 5 is configured to be hermetically and freely lifted up and down between the processing position for forming a film on the wafer W ( Figure 1 the position shown) and the transfer position below this processing position for transferring the wafer W via the loading / unloading port 22.

[0047] In addition, below the mounting stage 5, a plurality of support pins 27 are provided which are configured to be freely lifted up and down by a lifting mechanism 271 and support and lift the wafer W from the lower surface side of the wafer W when transferring the wafer W.

[0048] <Film-forming gas supply unit 3>

[0049] The top of the processing container 2 is configured as a film-forming gas supply unit 3. As described above, this film-forming gas supply unit 3 includes a shower head 31 and an upper-side member 32. The shower head 31, which is a horizontal plate-like member, is arranged facing the wafer W placed on the mounting stage 5 and is configured, for example, as a circular shape with a diameter larger than the diameter of the wafer W when viewed from above. In this shower head 31, a plurality of ejection holes 311 for supplying a film-forming gas toward the wafer W placed on the mounting stage 5 are dispersedly provided in a region facing the wafer W mounting region on the mounting stage 5 and along the thickness direction of the shower head 31.

[0050] The upper-side member 32 is configured to form a diffusion space 30 for the film-forming gas communicating with each ejection hole 311 between the upper-side member 32 and the shower head 31. The diffusion space 30 in this example is a flat space that is circular when viewed from above. As described above, the upper-side member 32 includes a flow-path forming member 33 and a top plate member 34. The top plate member 34 is provided, for example, so as to straddle the upper surface of the flow-path forming member 33 and the upper surface of the exhaust pipe 24 and be connected to them, and a ring-shaped protrusion 35 protruding downward is provided between the flow-path forming member 33 and the exhaust pipe 24. In other words, the flow-path forming member 33 is arranged so as to be surrounded by the protrusion 35. The flow-path forming member 33 is a circular block, and a concave portion is formed on the lower surface, and this concave portion forms the diffusion space 30.

[0051] The outer peripheral side of the upper surface of the shower head 31 is set to contact the lower surface of the protrusion 35 of the upper-side member 32, as Figure 4A shown, and the shower head 31 and the protrusion 35 are joined by a threaded member 36. In Figure 4AOnly one threaded member 36 is shown, but a plurality of threaded members 36 are provided at intervals in the circumferential direction of the spray head 31 and are threadedly fixed at a plurality of positions. In addition, a gap 37 is formed between the outer peripheral surface of the flow path forming member 33 and the inner peripheral surface of the protruding portion 35.

[0052] As Figure 4A shown, between such a spray head 31 and the upper side member 32, an annular first sealing member 41 is provided in a manner that is in close contact with the flow path forming member 33 of the spray head 31 and the upper side member 32 and surrounds the diffusion space 30 in a plan view. In addition, an annular second sealing member 42 is provided in a manner that is in close contact with the protruding portion 35 of the spray head 31 and the upper side member 32 and surrounds the first sealing member 41 in a plan view. And, in this example, between the flow path forming member 33 and the top plate member 34, a third sealing member 43 is also provided on the outer peripheral side of the flow path forming member 33 in a manner that is in close contact with these members. Thereby, it is possible to prevent the gas supplied from the gas introduction path 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 also provided around the threaded member 36, thereby ensuring the airtightness of the threaded hole to the outside.

[0053] The first to fourth sealing members 41 to 44 are formed of an elastic annular member such as an O-ring, for example, made of resin. In Figure 1 , Figure 4A etc., the O-rings constituting the sealing members 41 to 43 are depicted between the members in close contact with each other, but actually as Figure 4B illustrated, a groove portion 45 is formed in one of the members in close contact with each other, and the O-ring 46 is disposed in the groove portion 45, and the members are hermetically sealed by the restoring force of the O-ring 46.

[0054] As Figure 4A and Figure 4B shown, the film-forming gas supply unit 3 is provided with a gas discharge path 6. This gas discharge path 6 is formed such that its upstream end opens to a gap 38 formed by the first sealing member 41, the second sealing member 42, the spray head 31, and the upper side member 32, and its downstream end opens to the inside of the processing container 2. The gap 38 is a minute gap formed at the joint portion of the spray head 31 and the protruding portion 35 of the upper side member 32, and is sometimes referred to as the "joint portion gap 38".

[0055] As Figure 4B shown, the gas discharge path 6 of this example is formed in the spray head 31 and includes a downstream discharge path 61 forming the downstream side of the gas discharge path 6 and an upstream discharge path 62 forming the upstream side. In addition, in the gas discharge path 6, the joint portion gap 38 side is set as the upstream side, and the side where the gas goes by the exhaust inside the processing container 2 is set as the downstream side.

[0056] A recess 7 is formed on the upper surface of the shower head 31. The recess 7 opens to the joint portion gap 38 and together with a connection path forming member 8 to be described later constitutes the upstream side of the gas discharge path 6. More specifically, the recess 7 is provided at the peripheral portion of the shower head 31 so as to face the protruding portion 35 of the upper side member 32, and is disposed in an area outside the area of the shower head 31 facing the wafer W. As will be described later, film formation is performed in the recess 7 by the film formation gas flowing backward in the gas discharge path 6, but this is film formation at a position outside the area facing the wafer W. Therefore, even if a slight change occurs in the temperature distribution on the lower surface of the shower head 31 due to this film formation, the change in the temperature distribution will not affect or will slightly affect the in-plane temperature distribution of the wafer W, so this is preferable. In addition, the recess 7 is locally provided in the circumferential direction of the shower head 3. Therefore, the position where film formation is performed by the above-mentioned backward-flowing film formation gas can be suppressed to be small, so that the influence on the in-plane temperature distribution of the above-mentioned wafer W can be more reliably suppressed, so this is preferable.

[0057] As Figure 4B , Figure 5 shown, the recess 7 of this example is configured to be square in plan view and square in side view, and the recess 7 has a horizontal bottom surface 71 and vertical side walls 72. Moreover, for example, the downstream discharge path 61 is formed such that its downstream end opens near the opening portion 241 of the exhaust pipe 24 at the side portion of the shower head 31 and extends in the lateral direction (X direction), and then bends upward, and its upstream end opens to the bottom surface 71 of the recess 7.

[0058] A metal connection path forming member 8 is buried inside the recess 7 so as to close the opening of the downstream discharge path 61. The connection path forming member 8 is used to form a local narrow portion in the gas discharge path 6 and to form a connection path for connecting the downstream discharge path 61 and the joint portion gap 38.

[0059] As Figure 4B , Figure 5 shown, the connection path forming member 8 of this example is formed in a prism shape that is one size smaller than the recess 7. Thus, when the connection path forming member 8 is buried in the recess 7, the side wall 82 of the connection path forming member 8 is separated from the side wall 72 of the recess 7, and an upstream discharge path 62 is formed between the side walls 72 and 82.

[0060] The bottom surface 81 of the connection path forming member 8 constitutes a connection surface that abuts against the bottom surface 71 of the recess 7, and a minute groove 83 extending in the lateral direction (X direction) is provided on the bottom surface 81. In this example, as Figure 6AAs shown, the longitudinal cross-sectional shape of the groove 83 is triangular. When the connection path forming member 8 is buried in the recess 7, a flow path is formed between the groove 83 and the bottom surface 71 of the recess 7. Further, by making the longitudinal cross-sectional shape of the groove 83 triangular in this way, the flow conductance of the flow path becomes smaller, and it is possible to more reliably suppress the inflow of the film-forming gas, which will be described later, into the joint gap 38. Therefore, this is preferable. However, the cross-sectional shape is arbitrary, and it may be square, for example. The flow path formed by the groove 83 extends horizontally in the lateral direction (X direction), and is connected to the downstream discharge path 61 at a position approximately in the center of its length. Both ends of the flow path are connected to the upstream discharge path 62, respectively. Thus, the flow path formed by the groove 83 functions as a connection path for connecting the downstream discharge path 61 and the joint gap 38 via the upstream discharge path 62.

[0061] The cross-sectional area of the flow path formed by the groove 83 is smaller than the cross-sectional areas of the upstream discharge path 62 and the downstream discharge path 61, and is, for example, 1 / 2 or less. Thus, the flow path formed by the groove 83 is configured as a narrow portion 63 where the gas discharge path 6 narrows in the middle. The upstream discharge path 62 is formed by the side wall 82 of the connection path forming member 8 and the side wall 72 of the recess 7, and thus has a rectangular shape in a cross-sectional view. Therefore, its cross-sectional area is the area of this rectangle. Further, the flow path diameter of the downstream discharge path 61 is, for example, 1 to 3 mm, and the flow path diameter of the narrow portion 63 is, for example, 0.1 to 0.5 mm. The cross-section of the flow path of the downstream discharge path 61 is circular. However, as described above, the cross-section of the flow path of the narrow portion 63 (the cross-section of the groove 83) is triangular or square, and is not circular. The flow path diameter of the narrow portion 63 described here is the flow path diameter (the diameter of the flow path) when the cross-section of the triangular or square flow path is deformed into a circle having the same area.

[0062] In this way, the gas discharge path 6 is formed by connecting the downstream discharge path 61, the narrow portion 63, and the upstream discharge path 62. Thus, when observing the gas discharge path 6 from the downstream end, the upstream end of the downstream discharge path 61 is connected to the narrow portion 63, the flow path narrows and bends laterally, and further, the flow path bends longitudinally to form the upstream discharge path 62 and is connected to the joint gap 38.

[0063] Further, if the length L1 (the length of the narrow portion 63) in the X direction of the connection path forming member 8 is too long, it may impede the discharge of the atmosphere from the gaps 37 and 38 described later. If it is too short, it may cause the inflow of the film-forming gas described later into the gaps 37 and 38. From this viewpoint, it is preferable to set the length L1 to, for example, 1 mm to 100 mm. Further, the length L2 in the Y direction of the connection path 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. In addition, the flow path diameter and the size of the connection path forming member 8 shown 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). In addition, in each figure, the upper surface of the connection path forming member 8 is shown in contact with the protruding portion 35 of the upper-side member 32, but it is not necessary to be in contact like this and they may be separated.

[0064] Return Figure 1 Continuing the description, in the upper-side member 32, for example, a heating unit 39 is disposed between the flow path forming member 33 and the top plate member 34 so as to face the diffusion space 30.

[0065] And, a gas supply path 91 for introducing a film-forming gas is connected to the upper-side member 32, and a gas introduction path 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. The upstream side of the gas flow path 331 is connected to the gas introduction path 341, and the downstream side branches and is 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 path 91 reaches the diffusion space 30 via the gas introduction path 341 and the gas flow path 331, and is ejected from each ejection hole 311 toward the mounting table 5.

[0066] In Figure 1 As the gas supply system 9, a supply source 92 of a plurality of gases and a plurality of gas supply paths 91 branched on the upstream side are shown together. The gas supply system 9 will be described by taking as an example the case of forming a titanium nitride film (TiN film) on the wafer W. For example, the film-forming apparatus 1 is configured to alternately supply two kinds of gases as film-forming gases to the processing container 2 and form a TiN film by ALD (Atomic Layer Deposition) method. As the film-forming gas, 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.

[0067] The gas supply source 92 includes a raw material gas supply source and a reaction gas supply source, which are respectively connected to the film-forming gas supply unit 3 via the gas supply path 91. A flow control unit 93 including a valve for supplying and cutting off the gas, a flow rate adjustment unit for adjusting the gas supply amount, etc., and a storage tank for a gas (not shown) are provided in each gas supply path 91. The TiCl4 gas and the NH3 gas are supplied into the processing container 2, for example, after being temporarily stored in the storage tank and boosted to a specified pressure.

[0068] In addition, the gas supply source 92 further includes a displacement gas supply source and a cleaning gas supply source, and each supply source is connected to the film-forming gas supply unit 3 via the gas supply path 91. As the displacement gas, an inert gas such as nitrogen (N2 gas) or argon (Ar gas) can be used, and as the cleaning gas, for example, NF3 gas can be used.

[0069] As Figure 1 As shown, the film-forming apparatus 1 includes a control unit 100 that controls the operations of the respective parts constituting the film-forming apparatus 1. The control unit 100 is constituted by, for example, a computer including a CPU (not shown) and a storage unit, and a program incorporating a set of steps (commands) for controlling the film formation of the TiN film described later is stored in the storage unit. The program is stored in a storage medium such as a hard disk, an optical disk, a magneto-optical disk, a memory card, or a non-volatile memory, and is installed in the computer from these storage media.

[0070] <Formation of TiN Film in Film-Forming Apparatus>

[0071] Next, taking the case where the film formation process is restarted again after the maintenance of the film-forming apparatus 1 is completed as an example, a method for performing the film formation process of the TiN film using the film-forming apparatus 1 having the structure described above will be described.

[0072] As described above, the maintenance includes the steps of disassembling and assembling the film-forming gas supply unit 3 in an atmospheric atmosphere. Through this maintenance, in the film-forming gas supply unit 3, a state is formed in which the atmosphere exists 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 side member 32, and the gas discharge path 6.

[0073] Before the film formation process is carried out, the inside of the processing container 2 is decompressed to a vacuum atmosphere to remove foreign substances such as residual water. In parallel with this decompression, the heating unit 39 of the film-forming gas supply unit 3 is heated to a specified set temperature, for example, 170 °C, and the heating unit 51 of the mounting table 4 is heated to a specified set temperature, for example, 400 °C, so that the wafer W can be placed in the processing container 2 for processing.

[0074] Due to the heat conduction from the heating unit 39 and the radiant heat from the heating unit 51 caused by the temperature rise of the above-mentioned heating units 39 and 51, the temperature of the film-forming gas supply unit 3 rises, and the temperature of the atmosphere in the gaps 37 and 38 also rises, and the diffusivity of this atmosphere becomes higher. Since the inside of the processing container 2 is evacuated, the atmosphere with improved diffusivity like this flows out of the outside of the shower head 3 through the narrow part 63 of the gas discharge path 6 as shown by the dotted line of the atmosphere flow in Figure 7A and is exhausted toward the exhaust pipe 24.

[0075] In a state where the heating unit 39 of the film-forming gas supply unit 3 and the heating unit 51 of the stage 4 respectively reach the set temperature, the pressure inside the processing container 2 is set to a specified vacuum pressure, and the stage 5 has descended to the transfer position, the wafer W is stored in the processing container 2 through the coordinated operation of an external transfer mechanism (not shown) and the support pins 27. Then, the wafer W is placed on the stage 5 heated to the film-forming temperature (set temperature) by the heating unit 51, and the stage 5 is moved to the processing position.

[0076] Next, a film-forming step is performed in which a film-forming gas is supplied from the film-forming gas supply unit 3 to the surface of the wafer W heated to the film-forming temperature. In this step, the supply of the film-forming gas (TiCl4 gas, NH3 gas) and the gas (N2 gas) for replacing the atmosphere inside the processing container 2 is repeated in the order of TiCl4 gas → N2 gas → NH3 gas → N2 gas. At this time, the supply time of the TiCl4 gas and NH3 gas as the film-forming gas is, for example, 5 seconds or less.

[0077] As a result, the two film-forming gases adsorbed on the wafer W react with each other to form a molecular layer of TiN, and this molecular layer is stacked to form a titanium nitride film (TiN film).

[0078] In this way, the supply cycle of the above-mentioned film-forming gas and replacement gas is repeated about several tens to several hundreds of times to form a TiN film with a target film thickness. After that, the gas supply is stopped, the stage 3 is lowered to the transfer position, the gate valve 23 is opened, and the wafer W is taken out.

[0079] During film formation processing, since the downstream end of the downstream discharge path 61 opens into the processing container 2, film formation gas may sometimes flow backward and enter the downstream discharge path 61. However, the upstream end of the downstream discharge path 61 is connected to the narrow portion 63. Moreover, when observing the connection portion between the downstream discharge path 61 and the narrow portion (connection path) 63, the flow path direction of the downstream discharge path 61 and the flow path direction of the narrow portion 63 are different from each other, and this connection portion is formed as a curved flow path. In this way, in the gas discharge path 6, the flow path narrows at the narrow portion 63, and the flow direction of the gas changes. Therefore, at this narrow portion 63, the state where the film formation gas does not easily flow is formed.

[0080] Therefore, as shown by the single-dot chain line in Figure 7B for the flow of the film formation gas, the upstream flow of the film formation gas is suppressed by the narrow portion 63 formed by the connection path forming member 8, and the film formation gas does not easily reach the upstream discharge path 62, and the intrusion of the film formation gas into the upstream discharge path 62 can be suppressed.

[0081] In particular, in the ALD method, the supply time of the TiCl4 gas and the NH3 gas as the film formation gas is extremely short. Therefore, the film formation gas stays in the narrow portion 63, and the intrusion of the film formation gas into a position upstream of the narrow portion 63 can be further prevented.

[0082] By doing so, the film formation gas stays in the narrow portion 63. As shown in Figure 8A , the film 90 is deposited in this narrow portion 63, but the film formation is limited to this area. Moreover, due to the film formation, the narrow portion 63 becomes a state where the flow path becomes further narrow. Therefore, the intrusion of the film formation gas into a position upstream of the narrow portion 63 can be further suppressed. Therefore, the film formation gas does not reach the joint portion between the shower head 31 and the upper side member 32, and the film formation at the joint portion can be suppressed.

[0083] After performing the film formation processing of the TiN film on a plurality of wafers W in the film formation apparatus 1 in this way, cleaning is performed. For example, the inside of the processing container 2 is evacuated to a vacuum via the exhaust pipe 24 by the exhaust mechanism 26 and heated by the heating units 39 and 51, and NF3 gas as a cleaning gas is supplied from the gas supply system 9 as shown by the solid line in Figure 8A to perform this cleaning.

[0084] The cleaning gas is supplied into the processing container 2 via the film formation gas supply unit 3, contacts the film attached to the inside of the processing container 2 to peel the film from the processing container 2. The cleaning gas containing the peeled film is discharged to the outside via the exhaust pipe 24 along with the exhaust performed by the exhaust mechanism 26.

[0085] At this time, as shown in Figure 8AAs shown, the cleaning gas also enters the gas discharge path 6 of the film forming gas supply unit 3 and contacts the film 90 attached to the narrow portion 63. As a result, the film 90 is peeled off from the narrow portion 63, and as shown by the thick line in Figure 8B , the cleaning gas containing the peeled-off film 90 is discharged through the gas discharge path 6 and removed.

[0086] According to the above-described embodiment, since the gas discharge path 6 is provided in the film forming gas supply unit 3, the gaps 37 and 38 formed by the first sealing member 41, the second sealing member 42, the shower head 31, and the upper side member 32 can be exhausted through the gas discharge path 6.

[0087] As a result, as described above, even if the atmosphere remains in the film forming gas supply unit 3, the atmosphere can be exhausted before the film forming process is performed, thereby suppressing the reaction between the atmosphere and the film forming gas during the film forming process. In other words, the evacuation time required for exhausting the atmosphere until the start of the film forming process is shortened, so that the processing efficiency of the apparatus can be improved.

[0088] In addition, by providing the local narrow portion 63 in the gas discharge path 6, the intrusion of the film forming gas into the joint portion between the shower head 31 and the upper side member 32 can be suppressed, thereby preventing film formation at the joint portion. As a result, the problem of damage to the joint portion due to film formation at the joint portion can be suppressed, thereby reducing the particle risk, and the heat conduction at the joint portion becomes good, and the temperature change of the shower head 31 between each process of the wafer W can be suppressed (further suppressing the change in the processing temperature between wafers W).

[0089] In addition, as Figure 8A described, in the film forming gas supply unit 3, film formation is performed at the narrow portion 63, that is, the joint portion between the shower head 31 and the connection path forming member 8. However, compared with the film forming gas supply unit 3A described in Figure 2 , the film forming area can be suppressed to be smaller. Therefore, the above-described risk of generating particles and the temperature change of the shower head 31 can be suppressed.

[0090] Further, in the film-forming gas supply section 3A, when the deterioration of the upper-side member 32 is accelerated due to film formation at the joint between the showerhead 31 and the upper-side member 32, the upper-side member 32 is replaced. However, since the upper-side member 32 forms the top plate of the processing container 2, it is relatively large. Therefore, the time and cost for replacement increase. On the other hand, even if the deterioration of the connection path forming member 8 is accelerated due to film formation at the joint between the showerhead 31 and the connection path forming member 8 in the film-forming gas supply section 3, only the connection path forming member 8, which is a relatively small member, needs to be replaced. Thus, a low-cost and simple operation can be performed. That is, in terms of device maintenance, the structure of the film-forming gas supply section 3 is advantageous.

[0091] In addition, in the above example, the narrow portion 63 is formed by burying the connection path forming member 8 having the groove 83 in the recess 7, so that the narrow portion 63 can be formed by a simple method.

[0092] The above-described film-forming apparatus of the present disclosure may also be Figure 9 a structure in which only the gas discharge path 60 is provided in the film-forming gas supply section 3C as shown. The gas discharge path 60 is formed such that its upstream end opens to the gap 38 formed by the first sealing member 41, the second sealing member 42, the showerhead 31, and the upper-side member 32, and its downstream end opens into the processing container 2. The flow path diameter of the gas discharge path 60 in this example is formed to be, for example, 1 mm to 5 mm. Other structures of the film-forming gas supply section 3C are the same as those of the film-forming gas supply section 3.

[0093] In this structure, the narrow portion 63 is not provided in the gas discharge path 60, but the gap 38 can be exhausted via the gas discharge path 60. Therefore, the atmosphere that has entered the film-forming gas supply section 3C during device manufacturing and maintenance can be exhausted and removed via the gas discharge path 60.

[0094] However, since the narrow portion 63 is not provided, film-forming gas may flow into the gap 37 and the gap 38. In terms of more reliably suppressing such inflow, the structure of the film-forming gas supply section 3 described in Figure 4B etc. is more preferable.

[0095] In addition, Figure 10is a horizontal cross-sectional top view of the shower head 31. In order to suppress the inflow of the film-forming gas into the gaps 37 and 38, it is preferable to form the gas discharge path 60 to be relatively long. On the other hand, in order to avoid forming the gas discharge path 60 in the region of the shower head 31 where the ejection holes 311 are formed (the region facing the wafer W), for example, as shown in this figure, the gas discharge path 60 is formed to extend in a direction inclined with respect to the straight line L0 connecting the point P1, which is the downstream end thereof, and the center P0 of the shower head 31 when viewed from above. In addition, the downstream discharge path 61 of the film-forming gas supply section 3 can also be formed to extend in a direction inclined with respect to the straight line L0 in the same manner as the gas discharge path 60 shown here. Figure 10 The gas discharge path 60 shown is formed to extend in a direction inclined with respect to the straight line L0.

[0096] In the film-forming gas supply section 3 of the above first embodiment, when forming the narrow portion 63 by the combination of the recess 7 and the connection path forming member 8, instead of forming the minute grooves on the bottom surface 81 of the connection path forming member 8, minute grooves can also be formed on the bottom surface 71 of the recess 7.

[0097] In addition, the positional relationship between the recess 7, the gas discharge path 6, and the connection path forming member 8 is not limited to the above example. For example, it can also be a structure in which the upstream end of the downstream discharge path 61 of the gas discharge path 6 opens to the side wall of the recess 7. In this case, the connection path forming member 8 is buried in the recess 7 in a manner that abuts against the side wall of the recess 7 and closes the opening of the downstream discharge path, and minute grooves are formed longitudinally on the surface of the connection path forming member 8 that abuts against the side wall of the recess 7. In this example, the narrow portion 63 extends longitudinally, one end of which opens to the gap of the joint portion, and one end of the narrow portion 63 constitutes the upstream end of the gas discharge path 6. In addition, instead of forming the grooves on the connection path forming member 8, the narrow portion can also be provided by forming grooves on the side wall of the recess 7.

[0098] Moreover, the gas discharge path 6 can be provided on the upper side member 32 instead of on the shower head 31. In this case, the recess 7 is provided on the lower surface of the upper side member 32 so as to open to the gap between the shower head and the upper side member 32. The upstream end of the downstream discharge path 61 opens to the recess 7, and the connection path forming member 8 is buried in the recess 7 in a manner that closes the opening, and minute grooves are formed in one of the connection path forming member 8 and the recess 7 to constitute the narrow portion 63.

[0099] The shapes of the recess 7 and the connection path forming member 8 provided in one of the shower head 31 and the upper side member 32 are not limited to the above structures. In addition, the narrow portion 63 provided in the gas discharge path 6 can also be formed in such a way that the flow path itself constituting the gas discharge path 6 is locally narrowed. That is to say, it can also be as Figure 9As shown, a gas discharge path 60 is formed such that the flow path diameter of a part of the gas discharge path 60 is smaller than that of other parts.

[0100] In addition, the film formation process of the present disclosure can be applied to a film formation process in which a wafer is stored in a processing chamber set to a vacuum atmosphere and a film formation gas is supplied to the wafer from a film formation gas supply unit to form a film. Therefore, the film formation process is not limited to ALD, and can also be CVD (Chemical Vapor Deposition). In addition, when applied to ALD, the ejection of the film formation gas is intermittent, and as illustrated, the ejection time for one time is relatively short. Thus, the inflow of the film formation gas from the narrow portion 63 into the gaps 37 and 38 can be more reliably suppressed.

[0101] In addition, the embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The above embodiments can be omitted, replaced, changed, and combined in various ways without departing from the appended claims and their gist.

[0102] 〔Evaluation Test〕

[0103] An evaluation test performed on the technology of the present disclosure will be described. Using Figure 1 the film formation apparatus 1 shown, a film formation process of a TiN film is performed on a plurality of wafers, followed by cleaning. Then, the film formation gas supply unit 3 is disassembled and the states of the shower head 31 and the upper side member 32 are observed and confirmed, thereby performing this evaluation test.

[0104] After performing maintenance on the film formation apparatus 1, the process of exhausting the atmosphere remaining in the film formation gas supply unit 3 was performed for 6 hours, and then this film formation process was started. The atmosphere exhausting process, the film formation process of the TiN film, and cleaning were performed as described above after maintenance.

[0105] In addition, for the film formation gas supply unit 3 (Example 1), it is replaced with Figure 9 the film formation gas supply unit 3C shown (Example 2), Figure 2 the film formation gas supply unit 3A of the conventional structure shown (Comparative Example 1), Figure 3An evaluation test was also carried out in the same manner for the film-forming gas supply section 3B (Comparative Example 2) of the conventional structure shown. In the film-forming gas supply section 3C of Example 2, the gas discharge path 60 is formed such that the flow path diameter is 1 mm and the length of the flow path from the downstream end to the portion bent upward (i.e., the length of the portion extending horizontally) is 70 mm. Further, the film-forming gas supply section 3 of Example 1 has a structure in which a recess 7 and a connection path forming member 8 are provided at the joint portion between the shower head 31 and the upper side member 32 in the gas discharge path 60 of the film-forming gas supply section 3C, and the flow path diameter of the narrow portion 63 is 0.1 mm. Also in this Example 1, the length of the flow path from the downstream end of the gas discharge path 60 to the portion bent upward is 70 mm, which is the same as that of Example 2.

[0106] Explain these results.

[0107] In the film-forming gas supply section 3A of Comparative Example 1, residues remained in the entire area on the back surface (upper surface) of the shower head 31 and constituting the joint portion with the upper side member 32, and it was confirmed that deterioration occurred due to damage etc. at this joint portion compared to before the film-forming process was carried out. It is considered that in this film-forming gas supply section 3A, the film-forming gas bypassed to the joint portion and film formation occurred over the entire joint portion in the shower head 31. Moreover, it is speculated that even if cleaning is carried out, it is difficult for the gas to bypass to the joint portion, and thus it has become a state where film-forming residues are attached.

[0108] Further, in the film-forming gas supply section 3B of Comparative Example 2, no residues were found on the back surface of the shower head 31, and thus it was confirmed that by providing the second sealing member 42, the film-forming gas was suppressed from bypassing to the joint portion between the shower head 31 and the upper side member 32.

[0109] However, attachment of a black film was confirmed at the position where the fourth sealing member 44 is provided around the threaded member 36. It is speculated that this is because the atmosphere remaining in the film-forming gas supply section 3B reacted with the fourth sealing member 44 and deteriorated the fourth sealing member 44.

[0110] Next, in the film-forming gas supply section 3C of Example 2, no film-forming residues were found on the back surface of the shower head 31, but a small amount of residues was confirmed near the upstream end of the gas discharge path 60 opening to the gap 38.

[0111] This residue is different in appearance from the black film of Comparative Example 2, and thus it is speculated that this residue is obtained by the film-forming gas entering the gas discharge path 60 for film formation. However, since the confirmed residue is a small amount, it was also confirmed that according to the structure of Example 2, it is effective in discharging the atmosphere remaining in the film-forming gas supply section 3C and suppressing film formation at the joint portion between the shower head 31 and the upper side member 32 compared to the conventional structure.

[0112] Moreover, in the film formation gas supply unit 3 of Example 1, no film formation residue was confirmed when observing the back surface of the showerhead 31, and no deterioration such as damage was confirmed at the joint portion between the showerhead 31 and the upper side member 32 compared to before the film formation process. Thus, it was confirmed that the residual atmosphere was exhausted in the film formation gas supply unit 3 of Example 1, thereby suppressing the reaction between the atmosphere and the film formation gas and suppressing the detour of the film formation gas.

[0113] Description of Reference Numerals

[0114] W: semiconductor wafer; 1: film formation apparatus; 2: processing container; 3: film formation gas supply unit; 30: diffusion space; 31: showerhead; 311: ejection hole; 32: upper side member; 39: gap; 41: first sealing member; 42: second sealing member; 6: gas discharge path.

Claims

1. A film forming apparatus, comprising: A processing container that stores a substrate, and the inside of the processing container is set to a vacuum atmosphere; A film forming gas supply unit, which includes a shower head and an upper side member. The shower head has a plurality of ejection holes for supplying a film forming gas for film forming on the substrate. The upper side member is disposed above the shower head in the processing container to form a diffusion space for the film forming gas communicating with each of the ejection holes; A ring-shaped first sealing member that is in close contact with the shower head and the upper side member and surrounds the diffusion space in a top view; A ring-shaped second sealing member that is in close contact with the shower head and the upper side member and surrounds the first sealing member in a top view; and A gas discharge path that is formed in the film forming gas supply unit such that its upstream end opens to a gap formed by the first sealing member, the second sealing member, the shower head, and the upper side member and its downstream end opens into the processing container.

2. The film forming apparatus according to claim 1, wherein The gas discharge path has a local narrow portion.

3. The film forming apparatus according to claim 2, wherein A recess that opens to the gap is provided on one of the upper surface of the shower head and the lower surface of the upper side member, The upstream end of the downstream side discharge path forming the downstream side of the gas discharge path opens to the recess, The film forming apparatus includes a connection path forming member that is buried in the recess so as to close the opening of the downstream side discharge path, and a connection path for connecting the downstream side discharge path and the gap is formed in the connection path forming member as the narrow portion.

4. The film forming apparatus according to claim 3, wherein The upstream end of the downstream side discharge path opens to the bottom surface of the recess, The connection path forming member is separated from the side wall of the recess, and an upstream side discharge path, which is the upstream side of the gas discharge path, is formed between the connection path forming member and the side wall, The connection path forming member includes: a connection surface that abuts against the bottom surface of the recess; and a groove that is formed on the connection surface so as to connect the downstream side discharge path and the upstream side discharge path to constitute the connection path.

5. The film forming apparatus according to claim 1, wherein The recess and the gas discharge path are provided on the shower head.

6. A film forming method, including the following steps: Storing a substrate in a processing container whose inside is set to a vacuum atmosphere; Supplying a film forming gas to the substrate through a film forming gas supply unit including a shower head and an upper side member to perform film forming. The shower head has a plurality of ejection holes, and the upper side member is disposed above the shower head in the processing container to form a diffusion space for the film forming gas communicating with each of the ejection holes; and Exhaust the gap formed by the annular first sealing member, the annular second sealing member, the shower head, and the upper-side member through the gas discharge path. The annular first sealing member is in close contact with the shower head and the upper-side member, and surrounds the diffusion space in a plan view. The annular second sealing member is in close contact with the shower head and the upper-side member, and surrounds the first sealing member in a plan view. The gas discharge path is formed in the film-forming gas supply portion such that the upstream end opens to the gap and the downstream end opens into the processing container.

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