Automatic pressure control device, film formation device and pressure control method

Abstract

To perform pressure control by facilitating gas replacement in an exhaust pipe and suppressing an influence of adhesion of a by-product.SOLUTION: An automatic pressure control device comprises a butterfly valve which has a valve body which is rotatably attached via a shaft to an annular valve seat whose inner wall surface forms a portion of an exhaust path and which changes an opening area of the exhaust path by being arranged in an inclined manner by changing an inclination angle with respect to a lateral cross section, and which controls a pressure in a processing container by changing the inclination angle of the valve body on the basis of a detection result of a pressure in the processing container. The valve body is configured such that a first tapered surface is formed in a region located on an end on a downstream side when being arranged in an inclined manner on the surface, a second tapered surface is formed in a region located on an end on an upstream side when being arranged in an inclined manner on a back surface, and an angle formed by a region excluding the first tapered surface of the surface and the first tapered surface and an angle formed by a region excluding the second tapered surface of the back surface and the second tapered surface are respectively greater than 95 degrees and equal to or less than 150 degrees.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an automatic pressure control device, a film forming apparatus, and a method for controlling pressure. [Background technology]

[0002] In the manufacturing process of semiconductor devices, for example, a source gas and a reactive gas are supplied into a processing vessel adjusted to a vacuum state to perform a film forming process on a substrate, that is, a semiconductor wafer (hereinafter, referred to as a wafer). Patent Document 1 describes a vacuum pressure control device that evacuates a vacuum chamber in a film forming technology on a wafer and controls the pressure in the vacuum chamber by a non-sealed butterfly valve installed in a pipe when adjusting the pressure in the vacuum chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-124133 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technology for promoting gas replacement in an exhaust pipe and controlling pressure while suppressing the effects of adhesion of by-products. [Means for solving the problem]

[0005] The automatic pressure control device disclosed herein is an automatic pressure control device that controls a pressure in a processing vessel to which a source gas for forming a film on a substrate is supplied, and a vacuum exhaust unit for evacuating gas from within the processing vessel; an exhaust path connecting the processing vessel and the vacuum exhaust unit; a butterfly valve including: an annular valve seat whose inner wall surface forms a part of the exhaust passage; and a valve body configured as a plate-like body for closing at least a part of a cross section that crosses the annular valve seat and rotatably attached to the valve seat via a shaft, the valve body being inclined at an angle relative to the cross section by the shaft to change an opening area of ​​the exhaust passage; and the butterfly valve controls the pressure in the processing vessel by changing the inclination angle of the valve body based on a detection result of the pressure in the processing vessel; Equipped with When viewed from the upstream side in the flow direction of gas in the exhaust passage, the upstream surface of the valve body is called the front surface and the downstream surface is called the back surface. When viewed from the upstream side in the flow direction of gas in the exhaust passage, a first tapered surface is formed on the front surface of the valve body in a region located at the end on the downstream side in the flow direction when the valve body is in the inclined arrangement, and a second tapered surface is formed on the back surface of the valve body in a region located at the end on the upstream side in the flow direction when the valve body is in the inclined arrangement, When the valve body is in the inclined position, the inclination angle is within the range of 10 degrees to 30 degrees, and the angle between the first tapered surface and the area of ​​the front surface excluding the first tapered surface, and the angle between the second tapered surface and the area of ​​the back surface excluding the second tapered surface, are each greater than 95 degrees and less than or equal to 150 degrees. Effect of the Invention

[0006] According to the present disclosure, pressure control can be performed while promoting gas replacement in the exhaust pipe and suppressing the effects of adhesion of by-products. [Brief description of the drawings]

[0007] [Figure 1] 1 is a vertical sectional side view of a film forming apparatus according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a vertical sectional side view showing an APC valve of the film forming apparatus. [Figure 3A] 4 is a cross-sectional view illustrating a valve body and an exhaust flow according to a first comparative example of the APC valve. FIG. [Figure 3B] 13 is a cross-sectional view illustrating a valve body and an exhaust flow according to a second comparative embodiment. FIG. [Figure 4]FIG. 2 is a cross-sectional view showing a valve body in the present disclosure. [Diagram 5] 4 is a cross-sectional view illustrating an exhaust flow in a mid-exhaust passage according to the present disclosure. FIG. [Figure 6] FIG. 11 is a cross-sectional view showing the valve body according to a modified example. [Figure 7] 4 is a graph showing a relationship between the inclination angle of the valve body and the pressure inside the processing vessel. [Figure 8A] 4 is a photograph showing the results of an evaluation test according to an embodiment. [Figure 8B] 4 is a photograph showing the results of an evaluation test according to an embodiment. [Figure 9A] 6 is a photograph showing the results of an evaluation test according to a comparative example. [Figure 9B] 6 is a photograph showing the results of an evaluation test according to a comparative example. [Figure 9C] 6 is a photograph showing the results of an evaluation test according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A single-wafer type film forming apparatus, which is one embodiment of the apparatus for forming a film on a wafer W (hereinafter referred to as a "film forming apparatus") of the present disclosure, will be described with reference to FIG. 1. The film forming apparatus 1 includes a processing vessel 10 for accommodating a substrate, for example, a wafer W, and a control unit 100. The control unit 100 is, for example, a computer, and has a data processing unit including a program, a memory, and a CPU. The program includes commands for sending control signals from the control unit 100 to each unit of the film forming apparatus 1 and for progressing each process related to film formation (film forming process). The program is stored in a storage unit such as a computer storage medium, for example, a flexible disk, a compact disk, a hard disk, an MO (magneto-optical disk), or a non-volatile memory, and installed in the control unit 100. The control unit 100 controls and operates each component in the film forming apparatus 1, which will be described later, according to an operation by an operator and a predetermined program.

[0009] The processing vessel 10 is made of a metal such as aluminum (Al) and has a generally cylindrical shape. A loading port 61 for loading or unloading the wafer W is formed in a sidewall of the processing vessel 10 and can be opened and closed by a gate valve 62. A mounting table 63 for horizontally supporting the wafer W is provided inside the processing vessel 10, and the mounting table 63 is formed in a disk shape from a ceramic material such as aluminum nitride (AlN) or a metal material such as an aluminum or nickel alloy. In this example, a substrate heater 64 is embedded in the mounting table 63 and serves as a heating unit for heating the wafer W to a temperature in the range of about 300° C. to 500° C. The outer peripheral region and side of the upper surface of the mounting table 63 are covered by a cover member 65 made of a ceramic material such as alumina.

[0010] The mounting table 63 is connected to a lifting mechanism 67 provided below the processing vessel 10 via a support member 66, and is configured to be freely raised and lowered between a processing position shown in FIG. 1 and a transfer position for the wafer W shown below the processing position by a dashed line. In FIG. 1, reference numeral 10a denotes a partition member for partitioning the inside of the processing vessel 10 into upper and lower sections when the mounting table 63 is elevated to the processing position. Three support pins 68 (only two are shown) are provided below the mounting table 63 in the processing vessel 10 so as to be freely raised and lowered by a pin lifting mechanism 69 provided below the processing vessel 10. The support pins 68 are inserted into through holes 63a of the mounting table 63 at the transfer position, and are configured to be able to protrude and retract from the upper surface of the mounting table 63, and are used to transfer the wafer W between an external transfer mechanism (not shown) and the mounting table 63. In the figure, reference numeral 71 denotes a bellows which separates the atmosphere inside the processing vessel 10 from the outside air and expands and contracts in accordance with the vertical movement of the mounting table 63 and the support pins 68, respectively.

[0011] A shower head 76 for supplying a processing gas into the processing vessel 10 in a shower-like manner is provided in the processing vessel 10, facing the mounting table 63. The shower head 76 includes a main body 77 fixed to the ceiling wall 10b of the processing vessel 10, and a shower plate 78 connected below the main body 77, and defines a gas diffusion space 79 therein. A circular protrusion 78a protruding downward is formed on the periphery of the shower plate 78, and gas discharge holes 78b are formed on the inner flat surface of the circular protrusion 78a. A gas supply mechanism 40 is connected to the gas diffusion space 79 via a gas introduction hole 81.

[0012] The gas supply mechanism 40 includes a source gas supply unit 41 configured to supply a source gas containing a raw material of a film to be formed on the wafer W to the processing vessel 10, a reactive gas supply unit 42 configured to supply a reactive gas that reacts with the source gas, and purge gas supply units 43 and 44 configured to supply a purge gas. The source gas supply unit 41 includes a source gas supply source 45 and a supply path 46, and the supply path 46 is provided with a flow rate adjustment unit 47, a storage tank 48, and a valve 49 from the upstream side.

[0013] Like the source gas supply unit 41, the reaction gas supply unit 42 includes a reaction gas supply source 51 and a supply path 52, and the supply path 52 is provided with a flow rate adjustment unit 53, a storage tank 54, and a valve 55 from the upstream side. The purge gas supply units 43 and 44 each include a purge gas supply source 56 and a supply path 57, and each supply path 57 is provided with a flow path adjustment unit 58 and a valve 59. The supply path 57 of one purge gas supply unit 43 is connected to the source gas supply path 46 in order to purge the source gas, and the supply path 57 of the other purge gas supply unit 44 is connected to the reaction gas supply path 52 in order to purge the reaction gas.

[0014] Hereinafter, an example will be described in which a hafnium oxide (HfO2) film is formed on the wafer W. In this case, the source gas is a hafnium (Hf)-based gas, specifically, a gas containing cyclopentadienyltris(dimethylamino)hafnium (CpHf(NMe2)3). The reactive gas is an oxygen-based gas, specifically, a gas containing ozone (O3). The purge gas is, for example, a nitrogen (N)-based gas, specifically, a gas containing nitrogen (N2). The above-mentioned components included in the gas supply mechanism 40 are controlled by the control unit 100.

[0015] An exhaust duct 84 having a circular ring shape, for example, a rectangular cross section, is disposed in the upper part of the side wall of the processing vessel 10. A slit 85 is provided along the inner peripheral surface of the exhaust duct 84, and an exhaust port 86 is formed in the outer wall of the exhaust duct 84. A top wall 10b is provided on the upper surface of the exhaust duct 84 so as to close the upper opening of the processing vessel 10 via an insulating member 87, and a seal ring 88 is used to hermetically seal the gap between the exhaust duct 84 and the insulating member 87.

[0016] The film forming apparatus 1 includes an automatic pressure control mechanism (automatic pressure controller) 2 that performs evacuation and pressure adjustment inside a processing vessel 10. The automatic pressure control mechanism 2 includes a vacuum evacuation unit 11 that evacuates gas inside the processing vessel 10, a pressure detection unit 12 that detects the pressure inside the processing vessel 10, an APC valve (Automatic Pressure Controller Valve, pressure adjustment valve) 3, a shut valve 14 that opens and closes an exhaust path 16, and an exhaust pipe 15 that connects these to an exhaust duct 84.

[0017] The exhaust pipe 15 forms an exhaust path 16 through which gas discharged from the exhaust duct 84 through an exhaust port 86 flows as an exhaust flow. The cross-sectional shape of the exhaust pipe 15 and the exhaust path 16 is, for example, a circle. The exhaust path 16 connects the exhaust port 86 of the exhaust duct 84, the pressure detection unit 12, the APC valve 3, the shut valve 14, and the vacuum exhaust unit 11 in this order. More specifically, the pressure detection unit 12 is provided immediately adjacent to the exhaust port 86. As a result, the pressure detection value of the pressure detection unit 12 can be regarded as the pressure detection value inside the processing vessel 10.

[0018] The vacuum exhaust unit 11 is configured with a vacuum pump, for example, a dry pump. The shutoff valve 14 is provided upstream of the vacuum exhaust unit 11 and is configured to be able to freely open and close the exhaust path 16. The shutoff valve 14 is used when closing the exhaust path 16.

[0019] FIG. 2(a) is a vertical cross-sectional side view of the APC valve 3, and FIG. 2(b) is a cross-sectional view taken along the line B-B' in FIG. 2(a). The APC valve 3 is, for example, a leak-type butterfly valve, and includes a drive mechanism 4 and a valve mechanism 5. The drive mechanism 4 includes a controller (not shown), a motor 6, and a shaft 7. The motor 6 includes a drive unit, a driver, an encoder, and a rotating shaft (all not shown). The rotating shaft is rotated by the drive unit. The pressure detection unit 12 and the driver of the motor 6 are connected to the controller. The controller acquires information on the target pressure from the control unit 100. The controller stores the rotation angle of the rotating shaft as an operation amount associated with, for example, the difference between the target pressure and the pressure detection value of the pressure detection unit 12. The driver of the motor 6 controls the rotation angle of the drive unit based on the rotation angle output from the controller according to the detection result of the pressure detection unit 12, thereby controlling the pressure of the processing vessel 10 to an arbitrary target pressure.

[0020] The base end side of the shaft 7 is connected to the rotating shaft of the motor 6 so that their central axes coincide with each other, and the rotating shaft of the motor 6 rotates around the central axis L of the rotating shaft, causing the shaft 7 to rotate around the central axis L. Hereinafter, the central axis L of the rotating shaft will be referred to as the rotating axis L of the shaft 7. The tip side of the shaft 7 is disposed inside the valve mechanism 5.

[0021] The valve mechanism 5 has a valve seat 20 having a main body with a circular ring shape attached to the exhaust pipe 15, and a valve element 30 provided inside the valve seat 20. The valve mechanism 5 is formed of, for example, stainless steel. The valve seat 20 is interposed in the middle of the exhaust pipe 15. The area inside the inner wall surface 21 of the main body of the valve seat 20 forms a cylindrical internal space, and forms a mid-way exhaust passage 22 that connects the exhaust passages 16 upstream and downstream of the valve seat 20. The exhaust flow flows almost uniformly into the upstream end of the mid-way exhaust passage 22 from the exhaust pipe 15 upstream of the APC valve 3. A valve seat heater 25 is embedded in the valve seat 20, and the inner wall surface 21 of the valve seat 20 is heated to about 200°C.

[0022] For ease of explanation, the following description of the APC valve 3 in this specification uses an XYZ Cartesian coordinate system. As shown in Figures 2(a) and 2(b), the direction from the upstream side to the downstream side of the APC valve 3 is referred to as "direction Y". The flow direction of the exhaust flow entering the mid-exhaust path 22 is parallel to direction Y. One direction perpendicular to direction Y is referred to as "direction X", and the direction perpendicular to direction Y and direction X is referred to as "direction Z". The tip side of the shaft 7 is provided penetrating the valve seat 20 in a portion extending radially from the center of the internal space.

[0023] The valve element 30 is made of a plate-like member and is provided in the internal space of the valve seat 20. Specifically, the valve element 30 is disk-shaped and can block at least a part of the annular cross section that crosses the valve seat 20. Note that the valve element 30 may be of other shapes, such as an elliptical or rectangular shape, in addition to the disk shape, and in this case, the cross sections of the valve seat 20 and the exhaust passage 16 will also be elliptical, rectangular, or other shapes.

[0024] When viewed from the upstream side of the exhaust passage 16, the valve element 30 has a front surface 31 which is the upstream surface, a back surface 32 which is the downstream surface, and an annular side surface 33 between the front surface 31 and the back surface 32. The valve element 30 is attached to the tip side of the shaft 7 so that an extension line of the shaft 7 is disposed along the diameter direction of the valve element 30. In other words, the central axis of the valve element 30 is the same as the rotation axis L of the shaft 7, and when the shaft 7 is rotated, the valve element 30 rotates around the rotation axis L. By rotating around the rotation axis L, the valve element 30 changes the inclination angle with respect to the transverse cross section of the valve seat 20.

[0025] As shown by the solid lines in Figures 2(a) and (b), when the inclination angle of the valve body 30 is zero degrees, the front surface 31 and the back surface 32 of the valve body 30 are arranged parallel to the cross section of the valve seat 20, and the mid-way exhaust passage 22 of the valve seat 20 is fully closed. When fully closed, a gap is formed between the side surface 33 of the valve body 30 and the inner wall surface 21 of the valve seat 20. The APC valve 3 of this example is configured as a leaky butterfly valve in that a gap is formed between the valve body 30 and the valve seat even when fully closed. In the leaky APC valve 3, the opening area of ​​the mid-way exhaust passage 22 when the valve body 30 is fully closed is the area of ​​the gap between the inner wall surface 21 of the valve seat 20 and the side surface 33 of the valve body 30. When the inclination angle of the valve body 30 is zero degrees, the conductance of the mid-way exhaust passage 22 is the smallest.

[0026] 2, when the inclination angle of the valve body 30 is, for example, 90 degrees, the front surface 31 and the back surface 32 of the valve body 30 are disposed perpendicular to the cross section of the valve seat 20, and the mid-way exhaust passage 22 is fully opened. When fully open, almost the entire mid-way exhaust passage 22 becomes an opening area. When the inclination angle of the valve body 30 is 90 degrees, the conductance of the mid-way exhaust passage 22 is the largest.

[0027] As described above, the APC valve 3 changes the amount of exhaust from the processing vessel 10 by changing the opening area of ​​the intermediate exhaust path 22 according to the tilt angle of the valve body 30, thereby controlling the pressure value in the processing vessel 10. For example, the automatic pressure control mechanism 2 adjusts the pressure in the processing vessel 10 to within a range of, for example, 133 Pa (1 torr) to 400 Pa (3 torr) before starting the film formation process in the film formation apparatus 1. At this time, the automatic pressure control mechanism 2 is configured to change the tilt angle of the valve body 30 of the APC valve 3 within a range of, for example, 10 degrees to 30 degrees. Thereafter, while performing constant exhaust by the vacuum exhaust unit 11, the tilt angle of the valve body 30 after the pressure adjustment may be fixed, and then the film formation process described below may be started. Also, pressure control for adjusting the pressure in the processing vessel 10 may be continued during the film formation process.

[0028] In the film forming process of the film forming apparatus 1, a film is formed by, for example, the ALD (Atomic Layer Deposition) method. In the ALD method, a first film forming process in which a source gas is supplied, a second film forming process in which a reactive gas is supplied, and a purge process in which only a purge gas is supplied after these processes are repeatedly performed. The gas supplied into the processing vessel 10 in each process is sequentially flowed into the exhaust path 16 of the automatic pressure control mechanism 2. In the film forming apparatus 1, the first film forming process, the second film forming process, and the purge process each end in, for example, about 1 second, and then the film forming apparatus 1 moves to the next process. At this time, the automatic pressure control mechanism 2 constantly exhausts the inside of the processing vessel 10, so that the gas replacement in the processing vessel 10 of the film forming apparatus 1 is completed, but the gas may remain in the exhaust path 16 of the automatic pressure control mechanism 2 and the replacement may not be completed. In such a case, the gas molecules contained in the remaining source gas and reactive gas react with each other in the exhaust path 16 of the automatic pressure control mechanism 2, and by-products are likely to be generated. As mentioned above, when the source gas is a hafnium-based gas and the reactant gas is ozone, the by-product is an oxide of hafnium, such as hafnium oxide (HfO2).

[0029] Such by-products are likely to be formed in places where stagnation of the exhaust flow occurs where gas is likely to remain, and in bent or narrowed places of the exhaust path 16 where the exhaust flow is likely to collide. In the automatic pressure control mechanism 2 of this embodiment, specifically, by-products are likely to be formed in the APC valve 3 and the shut valve 14. For this reason, the APC valve 3 is set to have a wider opening area of ​​the intermediate exhaust path 22 when the valve body 30 is fully closed than that of a conventional leak-type butterfly valve. In a typical leak-type butterfly valve, the width of the gap between the valve body 30 and the valve seat 20 when fully closed is, for example, 0.1 mm. In contrast, the APC valve 3 of this embodiment is set to have a width of the gap between the valve body 30 and the valve seat 20 when fully closed, for example, 0.5 mm around the entire circumference of these members 30 and 20. The width of the gap between the valve body 30 and the valve seat 20 is the width dimension of the gap between the valve body 30 and the valve seat 20 as viewed along the radial direction of the valve seat 20. It is preferable that the width of the gap between the valve body 30 and the valve seat 20 is 0.5 mm at all positions on the outer periphery of the valve seat 20. However, even if the width of the gap is less than 0.5 mm in some areas on the outer periphery, the gap may be 0.5 mm on average.

[0030] In this case, the width of the gap between the valve body 30 and the valve seat 20 when fully closed is not limited to the above example, and may be set within a range of 0.1 mm or more and less than 1 mm, and preferably within a range of 0.3 mm or more and 0.6 mm or less. As a result, compared to the conventional leak-type butterfly valve, the exhaust flow rate at the outer periphery of the valve body 30 in the mid-way exhaust passage 22 is increased, gas replacement in the exhaust passage 16 is promoted, and the generation of by-products is suppressed. In addition, since the width of the gap between the valve body 30 and the valve seat 20 is widened, there is also an effect of suppressing clogging of the gap with by-products.

[0031] As shown in FIG. 4 described later, the valve body 30 of the present disclosure has tapered surfaces (upstream tapered surface 36, downstream tapered surface 35) on both the front surface 31 and the back surface 32. Here, for comparison with the present disclosure, the influence of the shapes of the valve body 30A of the first comparative embodiment and the valve body 30B of the second comparative embodiment, which have a different shape from the valve body 30, on the tendency to generate by-products will be described (FIGS. 3A and 3B). FIG. 3A is a cross-sectional view showing the valve body 30A of the first comparative embodiment, and FIG. 3B is a cross-sectional view showing the valve body 30B of the second comparative embodiment. These cross-sectional views show a cross section at a diameter position perpendicular to the rotation axis L of the shaft 7 and passing through the center of the disk-shaped valve body 30. The arrows shown in FIG. 3A and FIG. 3B indicate the flow of the exhaust flow, and the thickness of the arrow indicates the magnitude relationship of the flow rate of each exhaust flow. In these figures, the state in which the inclination angle of the valve bodies 30A and 30B is set to 15 degrees is illustrated.

[0032] 3A and 3B, the valve bodies 30A and 30B are located farthest from the rotation axis L at both ends 34A and 34B where the diameter of the valve body 30 perpendicular to the rotation axis L intersects with the end of the valve body 30. Therefore, when the valve bodies 30A and 30B are inclined, these both ends 34A and 34B are located farthest from the inner wall surface 21 of the valve seat 20. When viewed along the circumferential direction of the valve bodies 30A and 30B, the ends of the valve bodies 30A and 30B gradually approach the inner wall surface 21 of the valve seat 20 from the both ends 34A and 34B toward the intersection with the rotation axis L of the shaft 7, and are located with the above-mentioned 0.5 mm gap therebetween.

[0033] Therefore, in the valve body 30 in the tilted position, the fluid conductance at both ends 34A, 34B is greater than the conductance at the other end closer to the rotation axis L. This becomes more noticeable as the tilt angle of the valve body 30 increases.

[0034] As shown in FIG. 3A, the valve body 30A of the first comparative embodiment has an annular downstream tapered surface 35A formed around the entire downstream periphery, which is the periphery of the back surface 32A, which is the downstream surface. The angle between the back surface 32A and the downstream tapered surface 35A is set to, for example, 45 degrees. On the other hand, no tapered surface is formed on the upstream periphery, which is the periphery of the front surface 31, which is the upstream surface of the valve body 30A of the first comparative embodiment. With regard to the valve body 30A in such an inclined arrangement, of both ends 34A that are furthest from the rotation axis L, one located on the upstream side is referred to as the upstream end 37A, and the other located on the downstream side is referred to as the downstream end 38A.

[0035] In this case, the minimum width D1 of the gap between the upstream end 37A of the valve body 30A and the inner wall surface 21 of the valve seat 20 is larger than the minimum width D2 of the gap between the downstream end 38A of the valve body 30 and the inner wall surface 21 of the valve seat 20. For example, when the inclination angle is 15 degrees, the minimum width D1 of the gap is more than twice the minimum width D2 of the gap. Therefore, the conductance at the downstream end 38A of the valve body 30 is significantly smaller than the conductance at the upstream end 37B, and a flow bias occurs between the upstream end 37A and the downstream end 38A of the valve body 30. In this way, since an area where the conductance is small and almost no exhaust flow is formed, gas is likely to remain upstream of the valve body 30A.

[0036] In addition, when the exhaust flow uniformly flows in from the upstream of the APC valve 3 along the direction Y and flows along the surface 31A of the valve body 30A, the exhaust flow toward the upstream end 37A changes its flow direction when it reaches the surface 31A of the valve body 30A. At this time, if the exhaust flow direction changes along the surface 31A of the valve body 30A and then a flow of the exhaust flow toward the upstream end 37A with a large conductance is formed, the flow direction changes at an acute angle, and stagnation is likely to occur. In particular, at the upstream end 37A, the mid-way exhaust passage 22A is narrowed to the minimum width D1 as the side surface 33A of the valve body 30A and the inner wall surface 21 of the valve seat 20 come close to each other, and then is expanded by the downstream tapered surface 35A. For the above reasons, stagnation of the exhaust flow becomes large just before the minimum width D1, and since a heater is not provided on the valve body 30A, by-products S1 are likely to be generated between the side surface 33A of the valve seat and the inner wall surface 21 of the valve seat 20 in that region.

[0037] On the other hand, the gap between the downstream end 38A of the valve body 30A according to the first comparative embodiment and the inner wall surface 21 of the valve seat 20 is rapidly narrowed to a minimum width D2, which is less than half the minimum width D1 on the upstream end 37A side. Therefore, the exhaust flow flowing through the gap on the downstream end 38A side is small, but stagnation is likely to occur. In addition, the gap on the downstream end 38A side is gradually expanded from the side surface 33A to the downstream tapered surface 35A. By forming such an intermediate exhaust passage 22A, by-products S2, which are smaller but denser than by-products S1 on the upstream end 37A side, are likely to be generated in the intermediate exhaust passage 22A.

[0038] The by-products S1 and S2 generated as described above hinder the rotation of the valve body 30A, making it difficult to change the inclination angle of the valve body 30A, and may also make it impossible to fully close the intermediate exhaust path 22. Therefore, the automatic pressure control mechanism 2 requires maintenance to remove the by-products S1 and S2 before it becomes difficult to rotate the valve body 30A.

[0039] The above-described problem of adhesion of by-products S1 and S2 is not limited to the valve body 30A according to the first comparative embodiment having only the downstream tapered surface 35A, as described with reference to FIG. 3A. As shown in FIG. 3B, the valve body 30B according to the second comparative embodiment has a ring-shaped upstream tapered surface 36B formed around the entire circumference of the upstream periphery, and no tapered surface is formed on the downstream periphery. The minimum width E2 of the gap between the downstream end 38B of the valve body 30B and the inner wall surface 21 of the valve seat 20 is larger than the minimum width E1 of the gap between the upstream end 37B of the valve body 30B and the inner wall surface 21 of the valve seat 20. For example, when the inclination angle is 15 degrees, the minimum width E2 of the gap is more than twice the minimum width E1 of the gap. Therefore, the conductance at the upstream end 37B of the valve body 30B is significantly smaller than the conductance at the downstream end 38B. In this way, since a region where the conductance is small and where almost no exhaust gas flows is formed, gas is likely to remain even on the upstream side of the valve body 30B.

[0040] In addition, when the exhaust flow uniformly flows in from the upstream of the APC valve 3 along the direction Y and flows along the surface 31B side of the valve body 30B, the exhaust flow toward the downstream end 38B changes its flow direction when it reaches the surface 31B of the valve body 30B. At this time, after the flow direction of the exhaust flow changes along the surface 31B of the valve body 30B, when the exhaust flow toward the downstream end 38B with a large conductance is formed, the flow direction changes to an obtuse angle. Next, the exhaust flow passes through the midway exhaust passage 22A at the downstream end 38B. At the downstream end 38B, the midway exhaust passage 22A is narrowed to a minimum width E2 as the upstream tapered surface 36B of the valve body 30B and the inner wall surface 21 of the valve seat 20 approach each other. Thereafter, the gap between the side surface 33B of the valve body 30B and the inner wall surface 21 of the valve seat 20 gradually expands, so that stagnation of the exhaust flow is likely to occur. For the above reasons, the stagnation of the exhaust flow becomes large just before the minimum width E2, and since a heater is not provided on the valve body 30B, a condition is created in which by-products are likely to be generated between the side surface 33B of the valve seat in that region and the inner wall surface 21 of the valve seat 20.

[0041] In addition, the gap between the upstream end 37B of the valve body 30B related to the second comparative embodiment and the inner wall surface 21 of the valve seat 20 is rapidly narrowed to a minimum width E1, which is less than half the minimum width E2 on the downstream end 38B side. Therefore, the exhaust flow flowing through the gap on the upstream end 37B side is small, but stagnation is likely to occur. In addition, the gap on the upstream end 37B side narrows stepwise from the upstream tapered surface 36B to the side surface 33A. It is considered that by-products are easily generated in the intermediate exhaust path 22B by forming such an intermediate exhaust path 22B. And, it is considered that by-products are generated in the narrowed portions at the downstream end 38B and the upstream end 37B, making it difficult for the valve body 30B to rotate.

[0042] As confirmed above in the first and second comparative embodiments, in the valve body 30A in which the downstream tapered surface 35A is formed only on the back surface 32A, and in the valve body 30B in which the upstream tapered surface 36B is formed only on the front surface 31B, by-products may be generated, which may prevent the valve body from fully closing. This is also considered to be the case for valve bodies that do not have the downstream tapered surface 35A or the upstream tapered surface 36B.

[0043] FIG. 4 shows a cross-sectional view of the valve body 30 in this embodiment. FIG. 4 also shows an example in which the inclination angle of the valve body 30 is 15 degrees. The valve body 30 in this embodiment has an upstream tapered surface 36 formed along the periphery of the front surface 31 of the valve body 30, a downstream tapered surface 35 formed along the periphery of the back surface 32 of the valve body 30, and a side surface 33 formed between the upstream tapered surface 36 and the downstream tapered surface 35. The upstream tapered surface 36 is an annular tapered surface provided around the entire circumference of the upstream periphery, and the downstream tapered surface 35 is an annular tapered surface provided around the entire circumference of the downstream periphery.

[0044] By providing such upstream tapered surface 36 and downstream tapered surface 35, when the valve body 30 is disposed at an angle, the minimum gap width F2 at the downstream end 38 and the minimum gap width F1 at the upstream end 37 are approximately the same size. Moreover, the minimum gap width F1 at the upstream end 37 can be widened to approximately the same extent as the minimum gap width D1 at the upstream end 37A of the first comparative embodiment shown in Fig. 3A. Furthermore, the minimum gap width F2 at the downstream end 38 can be widened to approximately the same extent as the minimum gap width E2 at the downstream end 38B of the second comparative embodiment shown in Fig. 3B.

[0045] In this way, when the valve body 30 of this embodiment is inclined, the minimum widths F2 and F1 of the gap at the downstream end 38 and the upstream end 37 are approximately equal to each other, and no unilateral restriction is formed. In this case, when the exhaust flow flows on the surface 31 side of the valve body 30, as shown in FIG. 5, the exhaust flow is more likely to change its flow direction at an obtuse angle toward the downstream end 38 than the exhaust flow that changes its flow direction at an acute angle toward the upstream end 37. On the other hand, in the mid-way exhaust passage 22, the above-mentioned minimum widths F2 and F1 are approximately the same dimension, so there is no significant difference in conductance when the exhaust flow flows through the downstream end 38 and the upstream end 37. Therefore, the exhaust flow is less likely to have a biased flow as in the first and second comparative forms, gas is less likely to remain upstream of the valve body 30 of the present disclosure, and the generation of by-products is generally suppressed throughout the entire exhaust passage 16.

[0046] Specifically, the upstream tapered surface 36 and the downstream tapered surface 35 are chamfered to form a taper angle of, for example, 45 degrees with the thickness direction of the valve body 30. In other words, the upstream tapered surface 36 and the downstream tapered surface 35 are formed to form an angle of 135 degrees with the front surface 31 or the back surface 32 of the valve body 30. The opening area of ​​the mid-way exhaust passage 22 at the downstream end 38 and the upstream end 37 is suddenly narrowed by the upstream tapered surface 36 so that the gap at the side surface 33 becomes the minimum width F1, F2, and then the downstream tapered surface 35 suddenly expands it.

[0047] The exhaust flow upstream of the valve body 30, which contains the source gas and the reaction gas retained here, is likely to collide with the upstream tapered surface 36 when it flows into the gap between the downstream end 38 or the upstream end 37 of the mid-exhaust passage 22 and the inner wall surface 21 of the valve seat 20. For this reason, by-products are likely to be generated and grow on the upstream tapered surface 36. Then, the exhaust flow with a reduced content of the source gas and the reaction gas that generate by-products passes through the side surface 33 and the downstream tapered surface 35, so that the adhesion of by-products in these regions is suppressed. On the other hand, in the region of the inner wall surface 21 of the valve seat 20 facing the upstream tapered surface 36, the exhaust flow is less likely to collide with the upstream tapered surface 36 than with the upstream tapered surface 36, and the adhesion of by-products is suppressed by heating by the valve seat heater 25.

[0048] However, the minimum width F2 of the gap between the downstream end 38 of the valve body 30 and the inner wall surface 21 of the valve seat 20 is approximately the same as the minimum width F1 of the gap between the upstream end 37 and the inner wall surface 21 of the valve seat 20, but in detail, it is slightly larger than the minimum width F1. And, as in the first and second comparative embodiments, when the exhaust flow flows on the surface 31 side of the valve body 30, the exhaust flow toward the upstream end 37 is likely to stagnate, and the exhaust flow toward the downstream end 38 is unlikely to stagnate. For this reason, the exhaust flow rate passing through the downstream end 38 tends to be greater than the exhaust flow rate passing through the upstream end 37. Therefore, the amount of by-products generated on the upstream tapered surface 36 tends to be greater at the downstream end 38 than at the upstream end 37.

[0049] As described above, the APC valve 3 suppresses the generation of by-products overall, and effectively grows the by-products on the upstream tapered surface 36 to remove residual gas, thereby preventing the by-products from adhering downstream of the APC valve 3. For this reason, by providing the APC valve 3 upstream of the shut valve 14, the adhesion of by-products to the shut valve 14 can be suppressed, and the shut valve 14 can be prevented from becoming uncontrollable.

[0050] The taper angles of the upstream tapered surface 36 and the downstream tapered surface 35 are not limited to 45 degrees, but are greater than 5 degrees and equal to or less than 60 degrees, preferably greater than 15 degrees and equal to or less than 45 degrees, and more preferably greater than 30 degrees and equal to or less than 45 degrees. In other words, the angle between the upstream tapered surface 36 and the front surface 31 of the valve body 30 and the angle between the downstream tapered surface 35A and the back surface 32 is not limited to 135 degrees, but is greater than 95 degrees and less than 150 degrees, preferably greater than 105 degrees and equal to or less than 135 degrees, and more preferably greater than 120 degrees and equal to or less than 135 degrees.

[0051] For example, when the inclination angle is 15 degrees to 30 degrees and the taper angle of the upstream taper surface 36 and the downstream taper surface 35 is, for example, 5 degrees or more, the minimum gap width F1 at the upstream end 37 of the valve body 30 and the minimum gap width F2 at the downstream end 38 increase as the taper angle increases. Also, as the taper angle increases, the difference between the minimum gap widths F1 and F2 decreases, and the difference in conductance at the upstream end 37 and the downstream end 38 can be reduced. In particular, when the taper angle of the upstream taper surface 36 and the downstream taper surface 35 is 15 degrees or more, the minimum gap width F1 at the upstream end 37 of the valve body 30 and the minimum gap width F2 at the downstream end 38 become equal to the distance between the side surface 33 of the valve body 30 and the valve seat 20. Therefore, the minimum width F1 and the minimum width F2 increase and decrease in accordance with the increase and decrease in the inclination angle, but are substantially the same as each other, thereby improving and uniforming the conductance.

[0052] Furthermore, when the upstream tapered surface 36 and the downstream tapered surface 35 are formed at a predetermined taper angle based on the side surface 33 as described above, setting the taper angle larger will widen the upstream tapered surface 36 and the downstream tapered surface 35. This increases the gap between the valve body 30 and the valve seat 20, improving conductance. Also, the upstream tapered surface 36 has a larger area for by-products to adhere to, while the downstream tapered surface 35 has an expanded flow path to suppress adhesion of by-products. From the above, it can be said that the larger the taper angles of the upstream tapered surface 36 and the downstream tapered surface 35, the more preferable they are.

[0053] On the other hand, if the taper angle is made large, the front surface 31 and back surface 32 of the valve body 30 will be significantly cut out by the upstream taper surface 36 and downstream taper surface 35. As a result, this may affect the assembly with other structures such as the shaft 7. In view of the above, although it depends on the specific specifications and structures of each automatic pressure control mechanism 2, from a comprehensive perspective, the taper angles of the upstream taper surface and downstream taper surface 35A are suitable within the above range, and it is particularly preferable to keep them in the range of 30 degrees or more and 45 degrees or less.

[0054] Furthermore, when the taper angle is smaller than the above-mentioned preferred range (for example, 3 degrees), the upstream taper surface 36 of the downstream end 38 and the downstream taper surface 35A of the upstream end 37 protrude toward the valve seat 20 beyond the side surface 33. This reduces the minimum gap values ​​F1, F2, narrowing the upstream taper surface 36 and the downstream taper surface 35. As a result, the conductance at the upstream end 37 and the conductance at the downstream end 38 decrease, increasing the amount of residual gas and making it easier for by-products to be generated.

[0055] As described above, for the APC valve 3, the gap width between the valve element 30 and the valve seat 20 when fully closed, and the taper angles of the upstream tapered surface 36 and the downstream tapered surface 35 are set within the above-mentioned range. As a result, the gap widths at the upstream end 37 and downstream end 38 of the valve element 30 are larger than the allowable rotation of the valve element 30 within the tilt angle range of 10 degrees to 30 degrees, improving conductance in a balanced manner and reducing residual gas to suppress the generation of by-products. In addition, the valve element 30 grows and collects by-products on the upstream tapered surface 36, suppressing the generation of by-products downstream.

[0056] In addition, the dimension of the upstream tapered surface 36 in the thickness direction of the valve body 30, that is, the thickness, is preferably larger than the thickness of the downstream tapered surface 35A in order to increase the amount of deposition of by-products. The thickness of the side surface 33, which is the maximum diameter of the valve body 30, is preferably, for example, 1 mm or less, and the smaller the better. This makes it possible to scrape off by-products adhering to the side surface 33 when the valve body 30 rotates. In addition, since the contact area of ​​the exhaust flow with the side surface 33 is reduced, it is possible to prevent a decrease in the flow rate of the exhaust flow and suppress the adhesion of by-products to the side surface 33, and for example, the upstream tapered surface 36 and the downstream tapered surface 35 can be widened.

[0057] The film forming process of the film forming apparatus 1 will be described below. First, the wafer W is loaded into the processing vessel 10, the gate valve 62 of the processing vessel 10 is closed, and the wafer W is accommodated in the processing vessel 10. Next, the heating of the wafer W by the substrate heater 64 is started, and the automatic pressure control mechanism 2 is operated. The automatic pressure control mechanism 2 is operated by making the vacuum exhaust unit 11 perform vacuum exhaust inside the processing vessel 10 while continuously supplying a purge gas at a predetermined flow rate from the purge gas supply units 43 and 44, opening the shut valve 14, and starting pressure measurement by the pressure detection unit 12. According to the pressure measurement value and the set value of the target pressure, the valve body 30 of the APC valve 3 is adjusted from a fully closed state to a predetermined tilt angle to be inclined. As a result, the vacuum exhaust unit 11 exhausts the inside of the processing vessel 10 through the exhaust path 16, and the APC valve 3 is controlled so that the inside of the processing vessel 10 approaches the target pressure. When the pressure in the processing vessel 10 becomes almost constant, the tilt angle of the valve body 30 is fixed.

[0058] The gas supply mechanism 40 performs a purge process in which only a purge gas is supplied to fill the processing vessel 10 with the purge gas, and then performs a first film formation process in which a source gas is supplied, a purge process, a second film formation process in which a reactive gas is supplied, and a purge process in that order to form film formation molecules one layer at a time on the wafer W. For this reason, the purge gas, the source gas, the purge gas, and the reactive gas are introduced into the processing vessel 10 in that order, and these gases pass through the exhaust path 16 in that order and are exhausted by the vacuum exhaust unit 11.

[0059] At this time, a film is formed on the wafer W in the first and second film forming steps. In addition, because the gas replacement in the processing vessel 10 is almost completed in the purge step due to the constant exhaust of the automatic pressure control mechanism 2, unnecessary by-products are not generally generated in the processing vessel 10. On the other hand, in the exhaust path 16 of the automatic pressure control mechanism 2, gas replacement may not be completed upstream of the APC valve 3 and the shut valve 14, etc., and by-products may be generated in the exhaust path 16. However, as described above, the valve body 30 is provided with an annular upstream tapered surface 36 and downstream tapered surface 35. The upstream tapered surface 36 and downstream tapered surface 35 act to improve and uniform the conductance at the entire peripheral end of the valve body 30, particularly at the upstream end 37 and downstream end 38, thereby reducing the residual source gas and reaction gas and suppressing the generation of by-products.

[0060] Moreover, by-products are actively grown on the upstream tapered surface 36 of the valve body 30 to reduce the amount of residual gas in the exhaust flow, thereby suppressing the generation of by-products downstream of the upstream tapered surface 36. Furthermore, since by-products are grown toward the upstream side along the upstream tapered surface 36 of the valve body 30, even if by-products are grown on the upstream tapered surface 36, the rotational movement of the valve body 30 is unlikely to be hindered. As described above, according to the APC valve 3 of the present disclosure, it is possible to reduce residual gas in the exhaust path 16 of the highly efficient film forming apparatus 1 and suppress the generation of by-products that hinder the rotational movement of the valve body 30.

[0061] The APC valve 3 of the present disclosure is a leak type, but is not limited thereto. If the upstream tapered surface 36 and the downstream tapered surface 35 are formed, the conductance can be improved and uniformed even in a sealed valve with a gap width of zero when fully closed. In addition, the valve body 30 of the present disclosure has the upstream tapered surface 36 and the downstream tapered surface 35 formed over the entire circumference of the valve body 30, but is not limited thereto. For example, the upstream tapered surface 36 may be provided at least only on the downstream end 38, or the upstream tapered surface 36 may be formed in localized areas on the downstream end 38 side and the upstream end 37 side. In other words, the upstream tapered surface 36 formed in an annular shape corresponds to the annular tapered surface on the surface 31 side in the claims, and includes a surface corresponding to the first tapered surface provided on the downstream end 38 and the third tapered surface provided on the upstream end 37.

[0062] Further, the downstream tapered surface 35 may be provided only at least on the upstream end 37, or the downstream tapered surface 35 may be formed in localized regions on the upstream end 37 side and the downstream end 38 side. In other words, the downstream tapered surface 35 formed in an annular shape corresponds to the annular tapered surface on the back surface 32 side in the claims, and includes a surface corresponding to the second tapered surface provided on the upstream end 37.

[0063] FIG. 6 shows the state in which the valve body 30a according to the modified example is inclined. FIG. 6 shows the valve body 30a in a fully closed state by a broken line. In the valve body 30a, the upstream tapered surface 36a is formed only in the area on the downstream end 38a side, and the downstream tapered surface 35a is formed only in the area on the upstream end 37a side. In this case, when the valve body 30a is inclined, the conductance of the upstream end 37a and the downstream end 38a, which have high conductance in the entire circumference of the valve body 30a, can be further improved and made uniform. Therefore, even with the valve body 30a of the modified example, it is possible to reduce the stagnation of the exhaust flow upstream of the valve body 30a, reduce residual gas, suppress the generation of by-products, and remove residual gas by growing by-products on the upstream tapered surface 36a of the downstream end 38a.

[0064] In addition, the film forming apparatus 1 and the automatic pressure control mechanism 2 according to the present disclosure have been described with reference to the film forming process by the ALD method in which a film is formed one layer at a time, but the effects are not limited to the film forming process by the ALD method. The film forming apparatus 1 and the automatic pressure control mechanism 2 according to the present disclosure can also control the pressure by promoting gas replacement in the exhaust pipe 15 and suppressing the influence of adhesion of by-products in other film forming processes such as the film forming process by the CVD (Chemical Vapor Deposition) method in which films are formed continuously. In addition, the film forming apparatus 1 and the automatic pressure control mechanism 2 according to the present disclosure can achieve the same effects even when a film forming process is performed by the pyrolysis CVD method in which a film is formed by a source gas alone without using a reaction gas. In such a film forming apparatus 1 and the automatic pressure control mechanism 2, for example, film forming molecules may be unintentionally deposited in the exhaust pipe 15 due to the thermal decomposition or reaction of molecules constituting various gases, and molecules containing at least some of the atoms constituting the molecules of various gases may unintentionally react in the exhaust pipe 15 to become by-products. Such products of the film-forming molecules in the exhaust pipe 15 and by-products of reactions of molecules containing at least some of the atoms that constitute the various gas molecules are unintended products and are therefore collectively referred to as by-products.

[0065] It should be noted that the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, modified, or combined in various forms without departing from the scope and spirit of the appended claims. EXAMPLES

[0066] (Preliminary experiment) An evaluation test was conducted to verify the effect of the automatic pressure control device in the film formation process according to the present disclosure. First, the width of the gap between the valve body 30 having the upstream taper surface 36 and the downstream taper surface 35 with a taper angle of 45 degrees and the valve seat 20 when fully closed was set within the above-mentioned range, and the pressure was controlled within the above-mentioned pressure value range. In order to perform the film formation process with the above-mentioned settings, a gas supply mechanism 40 that supplies source gas and reaction gas alternately at a flow rate of 10 L per minute at atmospheric pressure at a temperature of 0° C. was connected to a processing vessel 10 with a capacity of 30 L. In addition, an automatic pressure control mechanism 2 having a vacuum exhaust unit 11 that performs vacuum exhaust at 30 KL per minute was connected to the processing vessel 10.

[0067] As shown in Figure 7, the change in pressure value inside the processing vessel was examined by changing the tilt angle for sample 1 with a gap width of 0.1 mm when fully closed, sample 2 with a gap width of 0.3 mm, and sample 3 with a gap width of 0.5 mm when fully closed. In Figure 7, the two-dot chain line shows the pressure change for sample 1 with a gap width of 0.1 mm when fully closed, the one-dot chain line shows the pressure change for sample 2 with a gap width of 0.3 mm when fully closed, and the solid line shows the pressure change for sample 3 with a gap width of 0.5 mm when fully closed.

[0068] According to this result, the pressure in the processing vessel 10 could be controlled from 133 Pa (1 torr) to 400 Pa (3 torr) in any case with the inclination angle of the valve body 30 in the range of 10 degrees to 30 degrees. In detail, since the pressure in the processing vessel 10 can be controlled in the above-mentioned pressure range in a wide range of more than half of the inclination angle range of 10 degrees to 30 degrees, the pressure control in this range can be easily adjusted by the inclination angle of the valve body 30. On the other hand, for example, if the gap width at the fully closed time is made smaller than 0.1 mm, it is necessary to control the pressure in a relatively narrow range on the upper limit side of the inclination angle range of the valve body 30. Also, for example, as the gap width at the fully closed time is made larger than 0.5 mm, it becomes necessary to control the pressure in a relatively narrow range on the lower limit side of the inclination angle range of the valve body 30. For this reason, it is preferable that the gap width at the fully closed time is set in the above-mentioned range.

[0069] (Example) 8A and 8B are explanatory diagrams showing images obtained in an evaluation test of the automatic pressure control mechanism 2 using the valve body 30 manufactured according to the embodiment of the present disclosure. Fig. 8A is an image of the downstream end 38 of the valve body 30 obtained from the front side, and Fig. 8B is an image of the upstream end 37 of the valve body 30 observed from the back side. Figs. 8A and 8B show a state in which the automatic pressure control mechanism 2 using the valve body 30 of Fig. 4 described above is operated to form films on 17,000 wafers W.

[0070] The by-products on the upstream tapered surface 36 of the valve body 30 are linear by-products S generated on the upstream tapered surface 36 from the downstream side toward the upstream side, and these are densely generated along the circumferential direction of the upstream tapered surface 36 at the end except for the side of the rotation axis L. Moreover, the linear by-products on the upstream tapered surface 36 overlap and become thick on the upstream tapered surface 36 side of the surface 31. The by-products thus grown are unlikely to extend outward from the rotation path of the side surface 33 of the valve body 30 during tilting operation, and are unlikely to interfere with the rotation of the valve body 30 during tilting operation of the valve body 30.

[0071] Moreover, the linear by-products S extended relatively long on the upstream end 37 side and the downstream end 38 side, and were generated relatively more on the downstream end 38 side than on the upstream end 37 side. No adhesion of by-products was confirmed on the side surface 33 and the downstream tapered surface 35. The by-products on the surface 31 other than the upstream tapered surface 36 were more noticeable than the by-products on the back surface 32 other than the downstream tapered surface 35, but the adhesion of by-products was generally suppressed. Furthermore, no noticeable adhesion of by-products was confirmed on the inner wall surface 21 of the valve seat 20. Furthermore, although not shown, no noticeable adhesion of by-products was confirmed on the shut valve 14. From the above, according to the APC valve 3 of the embodiment, under the above conditions, adhesion to the entire exhaust path 16 was suppressed, and the valve body 30 effectively collected the by-products, while no problems occurred with the tilting operation of the APC valve 3.

[0072] (Comparative Example) 9A to 9C are explanatory diagrams showing images obtained in an evaluation test of the automatic pressure control mechanism 2 using the valve body 30A manufactured corresponding to the first comparative embodiment. Fig. 9A is an image of the upstream end 37 of the valve body 30A obtained from the front surface 31A side, Fig. 9B is an image of the downstream end 38 of the valve body 30A obtained from the back surface 32A side, and Fig. 9C is an image of the shut valve 14 obtained from the back surface side, which is the downstream surface. Figs. 9A to 9C show a state in which the automatic pressure control mechanism 2 using the valve body 30A of the first comparative embodiment of Fig. 3A described above is operated to form a film on 20,000 wafers W.

[0073] As shown in FIG. 9A, the by-products S1 that have grown large in part are attached to the upstream end 37 of the valve body 30 and the part of the inner wall surface 21 of the valve seat 20 near the upstream end 37. As shown in FIG. 9B, a small amount of by-products S2 are densely generated in the gap between the downstream end 38 of the valve body 30 and the inner wall surface 21 of the valve seat 20 along the periphery of the downstream tapered surface of the valve body 30. The by-products thus generated are arranged so as to obstruct the rotational trajectory of both ends 34 during the tilting operation. In addition, in the APC valve 3 of the comparative example, the by-products are irregularly attached to the upstream end 37 side of the valve body 30. For this reason, with the valve body 30A of the comparative example, the timing of maintenance is difficult to predict, and maintenance must be performed early.

[0074] 9A to 9C, by-products were visually confirmed widely over the entire area of ​​the valve body 30A, the inner wall surface 21 of the valve seat 20, and the downstream shutoff valve 14. This is thought to be because the exhaust flow stagnates on the upstream side of the valve body 30A, increasing the amount of residual gas, and by-products are generated over the entire area of ​​the part that comes into contact with the exhaust flow. In addition, the valve body 30A of the comparative example does not have an upstream tapered surface 36 with a predetermined taper angle like the valve body 30 of the present disclosure, so it is thought that the by-products are not sufficiently collected, and a large amount of by-products S3 also adheres to the downstream shutoff valve. [Explanation of symbols]

[0075] W wafer 2 Automatic pressure control mechanism 3 APC valve 7 Shaft 10 Processing vessel 11 Vacuum exhaust section 16 Exhaust duct 20 Valve seat 21 Inner wall surface 22 Mid-way exhaust duct 30 Valve body 30a Valve body 31 Surface 32 Back side 35 Downstream tapered surface 35a Downstream tapered surface 36 Upstream tapered surface 36a Upstream tapered surface 37 Upstream end 37a Upstream end 38 Downstream end 38a Downstream end

Claims

1. An automatic pressure control device for controlling a pressure in a processing vessel to which a source gas for forming a film on a substrate is supplied, comprising: a vacuum exhaust unit for evacuating gas from within the processing vessel; an exhaust path connecting the processing vessel and the vacuum exhaust unit; a butterfly valve including: an annular valve seat whose inner wall surface forms a part of the exhaust passage; and a valve body configured as a plate-like body for closing at least a part of a cross section that crosses the annular valve seat and rotatably attached to the valve seat via a shaft, the valve body being inclined at an angle relative to the cross section by the shaft to change an opening area of ​​the exhaust passage; and the butterfly valve controls the pressure in the processing vessel by changing the inclination angle of the valve body based on a detection result of the pressure in the processing vessel; Equipped with When viewed from the upstream side in the flow direction of gas in the exhaust passage, the upstream surface of the valve body is called the front surface and the downstream surface is called the back surface. When viewed from the upstream side in the flow direction of gas in the exhaust passage, a first tapered surface is formed on the front surface of the valve body in a region located at the downstream end in the flow direction when the valve body is in the inclined arrangement, and a second tapered surface is formed on the back surface of the valve body in a region located at the upstream end in the flow direction when the valve body is in the inclined arrangement, An automatic pressure control device in which, when the valve body is in the inclined position, the inclination angle is within a range of 10 degrees to 30 degrees, and the angle between the first tapered surface and the area of ​​the front surface excluding the first tapered surface, and the angle between the second tapered surface and the area of ​​the back surface excluding the second tapered surface, are each greater than 95 degrees and less than 150 degrees.

2. 2. The automatic pressure control device according to claim 1, wherein a third tapered surface is formed on the surface of the valve body in a region located at the upstream end in the flow direction when the valve body is in the inclined arrangement, and by-products generated due to the source gas remaining in the exhaust path are grown on the first and third tapered surfaces.

3. 3. The automatic pressure control device according to claim 2, wherein an annular tapered surface is formed on the surface of the valve body along a peripheral portion of the valve body, and the first tapered surface and the third tapered surface are included in the annular tapered surface on the surface side.

4. 2. The automatic pressure control device according to claim 1, wherein an annular tapered surface is formed annularly along a peripheral portion of the valve body on a back surface of the valve body, and the second tapered surface is included in the annular tapered surface on the back surface side.

5. the butterfly valve is configured as a leaky butterfly valve in which a gap is formed between an inner periphery of the valve seat and an outer periphery of the valve body when the inclination angle is 0 degrees and the valve is fully closed, The automatic pressure control device according to claim 1 , wherein the width of the gap is equal to or greater than 0.1 mm and less than 1 mm.

6. The automatic pressure control device according to any one of claims 1 to 4; the processing vessel housing a substrate on which the film is to be formed; a gas supply mechanism that supplies the source gas to the processing vessel; A film forming apparatus comprising:

7. A method for controlling pressure in a processing vessel included in a film forming apparatus to which a source gas is supplied, comprising the steps of: a gas supply mechanism of the film forming apparatus supplying the source gas into the processing chamber; a butterfly valve having an annular valve seat, the inner wall surface of which forms a part of the exhaust passage; and a valve body, the valve body being configured as a plate for blocking at least a part of a cross section that crosses the annular valve seat and rotatably attached to the valve seat via a shaft, the valve body being tilted by the shaft to change an inclination angle with respect to the cross section and to change an opening area of ​​the exhaust passage, the butterfly valve controlling the pressure in the processing vessel by changing an inclination angle of the valve body based on a detection result of a pressure in the processing vessel, the valve body being tilted at an inclination angle of 10 degrees to 30 degrees from the upstream side in a flow direction of gas in the exhaust passage, the first tapered surface formed in an area located at a downstream end of the front surface in the flow direction of the valve body and the second tapered surface formed in an area located at an upstream end of the back surface in the flow direction, the first tapered surface being tilted at an inclination angle of 10 degrees to 30 degrees from the upstream side in the flow direction of gas in the exhaust passage, and growing by-products generated due to the source gas remaining in the exhaust path on the first tapered surface; Including, A pressure control method, wherein an angle between the front surface and the first tapered surface, and an angle between the back surface and the second tapered surface are each greater than 95 degrees and not greater than 150 degrees.

Images