Heater

Abstract

This heater comprises: a substrate on which a heating object is placed; a tube body secured on a bottom surface of the substrate; a first plate on which a bottom end section of the tube body is secured; a second plate disposed below the first plate and secured to a mounting base; one or more seal members configured in an annular shape and sealing the space between a bottom surface of the first plate and a top surface of the second plate; three or more first screws that are joined to screw holes in the second plate or to screw holes in the first plate so as to press the bottom surface of the first plate or the top surface of the second plate; and three or more second screws that fasten the first plate and the second plate so as to pull the bottom surface of the first plate toward the top surface of the second plate.

Description

heater

[0001] This application claims priority to Japanese Patent Application No. 2023-010761 filed on January 27, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] Patent Document 1 discloses a film formation apparatus for forming a thin film on a wafer. The film formation apparatus includes a chamber, a shower head, and a heater. The shower head supplies gas into the chamber. The shower head is provided on the ceiling wall of the chamber. The heater heats the wafer, which is the heating target. The heater includes a disk-shaped susceptor, a cylindrical support that supports the susceptor, and a mounting plate to which the lower end of the support is fixed. The susceptor is a substrate having an upper surface on which the wafer is placed and a lower surface opposite the upper surface. Within the chamber, the shower head faces the upper surface.

[0003] Japanese Patent Application Laid-Open No. 2007-067394

[0004] The heater of the present disclosure comprises a base on which an object to be heated is placed, a cylinder fixed to the underside of the base, a first plate to which the lower end of the cylinder is fixed, a second plate disposed below the first plate and fixed to a mounting base, one or more annular sealing members that seal the gap between the underside of the first plate and the upper side of the second plate, three or more first screws that are connected to the screw holes of the second plate or the screw holes of the first plate so as to press the underside of the first plate or the upper side of the second plate, and three or more second screws that fasten the first plate and the second plate so as to attract the underside of the first plate to the upper side of the second plate.

[0005] FIG. 1 is a schematic diagram showing a first example of a heater according to the first embodiment. FIG. 2 is a schematic diagram showing a second example of a heater according to the first embodiment. FIG. 3 is a schematic diagram showing a third example of a heater according to the first embodiment. FIG. 4 is a schematic diagram showing a fourth example of a heater according to the first embodiment. FIG. 5 is a schematic diagram showing a fifth example of a heater according to the first embodiment. FIG. 6 is an enlarged schematic diagram showing a first example of a region A in FIG. 1. FIG. 7 is an enlarged schematic diagram showing a second example of a region A in FIG. 1. FIG. 8 is a schematic diagram showing a first example of an arrangement of first screws and second screws provided in the heater according to the first embodiment. FIG. 9 is a schematic diagram showing a second example of an arrangement of first screws and second screws provided in the heater according to the first embodiment. FIG. 10 is a schematic diagram showing a third example of an arrangement of first screws and second screws provided in the heater according to the first embodiment. Fig. 11 is a schematic diagram showing a fourth example of an arrangement of the first screws and the second screws provided in the heater of embodiment 1. Fig. 12 is a schematic diagram showing a fifth example of an arrangement of the first screws and the second screws provided in the heater of embodiment 1. Fig. 13 is a schematic diagram showing a sixth example of an arrangement of the first screws and the second screws provided in the heater of embodiment 1. Fig. 14 is a schematic diagram showing a seventh example of an arrangement of the first screws and the second screws provided in the heater of embodiment 1. Fig. 15 is a schematic diagram showing an eighth example of an arrangement of the first screws and the second screws provided in the heater of embodiment 1. Fig. 16 is a schematic diagram showing a ninth example of an arrangement of the first screws and the second screws provided in the heater of embodiment 1. Fig. 17 is a schematic diagram showing a tenth example of an arrangement of the first screws and the second screws provided in the heater of embodiment 1. Fig. 18 is a schematic diagram showing an eleventh example of an arrangement of first screws and second screws provided in the heater of embodiment 1. Fig. 19 is a schematic diagram showing a twelfth example of an arrangement of first screws and second screws provided in the heater of embodiment 1. Fig. 20 is a schematic diagram showing a thirteenth example of an arrangement of first screws and second screws provided in the heater of embodiment 1. Fig. 21 is a schematic diagram showing a heater of embodiment 2. Fig. 22 is a schematic diagram showing an arrangement of first screws, second screws, and third screws provided in the heater of embodiment 2. Fig. 23 is a schematic diagram showing a first example of a heater of embodiment 3. Fig. 24 is a schematic diagram showing a second example of a heater of embodiment 3.

[0006] [Problem to be Solved by the Present Disclosure] When a mounting plate is fixed to a mounting base or the like so that the showerhead and the upper surface of the substrate face each other, the distance between the showerhead and the upper surface of the substrate may become uneven due to dimensional tolerances of each component, etc. If the distance is uneven, a thin film of uniform thickness cannot be formed on the surface of the wafer.

[0007] An object of the present disclosure is to provide a heater that can make the distance between the showerhead and the upper surface of the substrate uniform.

[0008] [Advantages of the Present Disclosure] The heater of the present disclosure can make the distance between the showerhead and the upper surface of the substrate uniform.

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be listed and described.

[0010] (1) A heater according to one aspect of the present disclosure comprises a base on which an object to be heated is placed, a cylinder fixed to the underside of the base, a first plate to which the lower end of the cylinder is fixed, a second plate disposed below the first plate and fixed to a mounting base, one or more annular sealing members that seal the gap between the underside of the first plate and the upper side of the second plate, three or more first screws that are connected to the screw holes of the second plate or the screw holes of the first plate so as to press against the underside of the first plate or the upper side of the second plate, and three or more second screws that fasten the first plate and the second plate so as to attract the underside of the first plate to the upper side of the second plate.

[0011] The heater (1) above can make the distance between the shower head and the upper surface of the substrate uniform. This is because the heater (1) above can locally adjust the distance between the lower surface of the first plate and the upper surface of the second plate using three or more first screws and three or more second screws. In other words, with the heater (1) above, even if the distance between the shower head of the film formation apparatus and the upper surface of the substrate becomes uneven when the heater is fixed to the mounting base, the distance between the shower head and the upper surface of the substrate can be adjusted so that it becomes uniform. Therefore, the heater (1) above can be used to construct a film formation apparatus that can form a thin film of uniform thickness on the surface of a wafer.

[0012] (2) In the heater of (1) above, the lower surface of the first plate or the upper surface of the second plate may have a first groove and a second groove arranged in an annular shape. The diameter of the second groove is larger than the diameter of the first groove. The depth of the first groove and the depth of the second groove are the same. The number of the one or more seal members is two, i.e., a first seal member and a second seal member. The thickness of the second seal member under no load is larger than the thickness of the first seal member under no load. The first seal member is disposed in the first groove. The second seal member is disposed in the second groove.

[0013] In the heater (2) described above, the second seal member is disposed farther from the center of the first plate than the first seal member. When the heater is in use, the first seal member and the second seal member are compressed by the first plate and the second plate. When the first screw and the second screw are operated to uniformly space the showerhead and the upper surface of the base, a space between the lower surface of the first plate and the upper surface of the second plate gradually widens from a position closer to the center of the first plate to a position farther away. If the depth of the first groove portion and the depth of the second groove portion are the same and the thickness of the first seal member and the second seal member are the same, the second seal member is less likely to be compressed by the first plate and the second plate than the first seal member at the space where the space gradually widens. In the heater (2) described above, the depth of the first groove portion and the depth of the second groove portion are the same, but the thickness of the second seal member is thicker than the thickness of the first seal member. Therefore, even in the area where the gap gradually widens, the second seal member is more likely to be compressed by the first and second plates than when the second seal member has the same thickness as the first seal member. Therefore, the heater described in (2) above is less susceptible to gas flowing inside than the second seal member.

[0014] (3) In the heater of (1) above, the lower surface of the first plate or the upper surface of the second plate may have a first groove and a second groove that are annularly arranged. The diameter of the second groove is larger than the diameter of the first groove. The depth of the second groove is shallower than the depth of the first groove. The number of the one or more seal members is two, i.e., a first seal member and a second seal member. The thickness of the first seal member under no load is the same as the thickness of the second seal member under no load. The first seal member is disposed in the first groove. The second seal member is disposed in the second groove.

[0015] In the heater of (3) above, even in the areas where the gap gradually widens, the second seal member is more easily compressed by the first plate and the second plate than when the depth of the first groove portion and the depth of the second groove portion are the same. Therefore, like the heater of (2) above, the heater of (3) above is less susceptible to gas flowing inside than the second seal member.

[0016] (4) In the heater of (2) or (3), the first groove and the second groove may be provided concentrically.

[0017] The heater (4) above is more likely to have a uniform length for adjusting the distance between the lower surface of the first plate and the upper surface of the second plate than when the first groove portion and the second groove portion are not arranged concentrically.

[0018] (5) In the heater of (4) above, the center of the first groove portion and the center of the second groove portion may be the center of the envelope circle of the first plate or the center of the envelope circle of the second plate.

[0019] The heater (4) above makes it easier to make the length by which the distance between the lower surface of the first plate and the upper surface of the second plate adjustable uniform, compared to when the centers of the first groove portion and the second groove portion are located at positions different from the centers of the envelope circles of the first plate and the second plate.

[0020] (6) In the heater according to any one of (1) to (5) above, the number of the three or more first screws and the number of the three or more second screws may be the same.

[0021] In the heater of (6) above, the number of first screws is the same as the number of second screws, which makes it easy to make the distance between the shower head and the upper surface of the base uniform.

[0022] (7) In any of the heaters described in (1) to (6) above, the three or more first screws may be arranged on the circumference of a first circle centered on the center of the envelope circle of the first plate, and the three or more second screws may be arranged on the circumference of a second circle centered on the center of the envelope circle of the first plate.

[0023] In the heater of (7) above, the distance from the center of the envelope circle of the first plate to each of the first screws is uniform, and the distance from the center of the envelope circle of the first plate to each of the second screws is uniform, so that the heater of (7) above makes it easy to make the distance between the showerhead and the upper surface of the base uniform.

[0024] (8) In the heater of (7) above, the first circle and the second circle may be the same circle.

[0025] In the heater of (8) above, the distance from the center of the envelope circle of the first plate to each of the first screws and the distance from the center of the envelope circle of the first plate to each of the second screws are uniform, which makes it easy to uniformize the distance between the showerhead and the upper surface of the base.

[0026] (9) In the heater of (7) above, the first circle and the second circle may be concentric circles having different radii.

[0027] In the heater of (9) above, although the distance from the center of the envelope circle of the first plate to each of the first screws and the distance from the center of the envelope circle of the first plate to each of the second screws are different, the distance from the center of the envelope circle of the first plate to each of the first screws is uniform, and the distance from the center of the envelope circle of the first plate to each of the second screws is uniform, so the heater of (9) above makes it easy to make the gap between the showerhead and the upper surface of the base uniform.

[0028] (10) In the heater of (8) or (9) above, the three or more first screws may be arranged at equal intervals on the circumference of the first circle, and the three or more second screws may be arranged at equal intervals on the circumference of the second circle.

[0029] When the first circle and the second circle are the same circle, in the heater of (10) above, the distance from the center of the envelope circle of the first plate to each of the first screws and the distance from the center of the envelope circle of the first plate to each of the second screws are uniform, the spacing between adjacent first screws in a direction along the central axis is uniform, and the spacing between adjacent second screws in a direction along the central axis is uniform. Therefore, the heater of (10) above makes it easy to uniformize the spacing between the showerhead and the upper surface of the base.

[0030] When the first circle and the second circle are concentric circles with different radii, in the heater of (10) above, the distance from the center of the envelope circle of the first plate to each first screw is uniform, and the spacing between adjacent first screws in a direction around the central axis is uniform. Also, in the heater of (10) above, the distance from the center of the envelope circle of the first plate to each second screw is uniform, and the spacing between adjacent second screws in a direction around the central axis is uniform. Therefore, in the heater of (10) above, although the distance from the center of the envelope circle of the first plate to each first screw and the distance from the center of the envelope circle of the first plate to each second screw are different, it is easy to make the spacing between the showerhead and the upper surface of the base uniform.

[0031] (11) The heater according to any one of (7) to (10) above may further include three or more third screws that regulate the gap between the lower surface of the first plate and the upper surface of the second plate to a predetermined value or less. The number of the three or more third screws is the same as the number of the three or more first screws and the number of the three or more second screws. Each of the three or more third screws has a head facing the upper surface of the first plate, a shaft that penetrates the first plate, and a male thread that is coupled to the second plate.

[0032] The heater of (11) above can control the maximum distance between the lower surface of the first plate and the upper surface of the second plate using the third screw. This is because when the first plate is moved within a predetermined range in a direction away from the second plate, the upper surface of the first plate comes into contact with the head of the third screw, preventing the first plate from moving above the head. In other words, the heater of (11) above can prevent the lower surface of the first plate from moving too far away from the upper surface of the second plate. Therefore, the heater of (11) above can easily maintain a state in which the sealing member is compressed by the first plate and the second plate.

[0033] (12) In the heater of (11) above, the three or more third screws may be arranged on the circumference of a third circle whose center is the center of the envelope circle of the first plate.

[0034] In the heater of (12) above, the distance from the center of the envelope circle of the first plate to each third screw is uniform. In other words, in the heater of (12) above, the maximum gap between the lower surface of the first plate and the upper surface of the second plate tends to be uniform in the direction away from the center.

[0035] (13) In the heater of (12) above, the third circle may be the same circle as at least one of the first circle and the second circle.

[0036] The heater (13) above makes it easy to control the maximum distance between the lower surface of the first plate and the upper surface of the second plate, and makes it easy to make the distance between the showerhead and the upper surface of the substrate uniform.

[0037] (14) In the heater of (12) or (13) above, the three or more third screws may be arranged at equal intervals on the circumference of the third circle.

[0038] In the heater of (14) above, the distance from the center of the envelope circle of the first plate to each third screw is uniform, and the spacing between adjacent third screws in a direction around the central axis is uniform. In other words, in the heater of (14) above, the maximum spacing between the lower surface of the first plate and the upper surface of the second plate tends to be uniform in a direction around the central axis.

[0039] (15) In any of the heaters described in (1) to (14) above, a pin may be further provided which is sandwiched between the lower surface of the first plate or the upper surface of the second plate and each of the three or more first screws.

[0040] If the pin is not provided, when the first screw is rotated to adjust the gap between the lower surface of the first plate and the upper surface of the second plate, the lower surface of the first plate or the upper surface of the second plate may be scraped if the first screw comes into direct contact with the lower surface of the first plate or the upper surface of the second plate.The heater described in (15) above, having the pin sandwiched therebetween, makes it easy to prevent the lower surface of the first plate or the upper surface of the second plate from being scraped by the rotated first screw.

[0041] (16) In the heater of (15) above, the lower surface of the first plate or the upper surface of the second plate may have a recess in which the pin is disposed.

[0042] The heater of (16) above can be in a state where the pin is stably pressed against the lower surface of the first plate or the upper surface of the second plate.

[0043] Details of the heater of the present disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same objects. The sizes of the components shown in the drawings are shown for the purpose of clarifying the description and do not necessarily represent the actual dimensional relationships.

[0044] <<Embodiment 1>> [Heater] A heater 1 of embodiment 1 will be described with reference to FIGS. 1 to 20. As shown in FIGS. 1 to 5, the heater 1 includes a base 2, a cylindrical body 3, and a plate 4. The base 2 has an upper surface 2a and a lower surface 2b on which a heating target is placed. The heating target is, for example, a silicon or compound semiconductor wafer. The cylindrical body 3 supports the base 2. An upper end 31 of the cylindrical body 3 is fixed to the lower surface 2b. A lower end 32 of the cylindrical body 3 is fixed to the plate 4. The plate 4 is fixed to a mounting base 9. One of the features of the heater 1 of embodiment 1 is that it satisfies the following requirements (A) to (C): (A) The plate 4 is composed of two plates, a first plate 41 and a second plate 42. (B) The heater 1 includes one or more seal members 6 disposed between the first plate 41 and the second plate 42. (C) The heater 1 has three or more first screws 51 and three or more second screws 52 that are arranged to allow local adjustment of the gap between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42.

[0045] The heater 1 of the first embodiment can be used in a film formation apparatus for forming a thin film on the surface of a wafer. In the film formation apparatus, the heater 1 is fixed to a mounting base 9 so that the showerhead faces the upper surface 2a of the substrate 2 in a chamber. The showerhead supplies gas into the chamber. When the heater 1 is fixed to the mounting base 9, the distance between the upper surface 2a of the substrate 2 and the showerhead may become uneven. If the distance is uneven, a thin film of uniform thickness cannot be formed on the surface of the wafer. In the heater 1 of the first embodiment, the distance between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42 can be locally adjusted by three or more first screws 51 and three or more second screws 52, which will be described in detail later. Therefore, the heater 1 of the first embodiment can uniformly maintain the distance between the showerhead and the upper surface 2a of the substrate 2. That is, with the heater 1 of embodiment 1, even if the gap between the upper surface 2 a of the base 2 and the shower head becomes uneven when the heater 1 is fixed to the mount 9, the gap between the upper surface 2 a of the base 2 and the shower head can be adjusted to become uniform. Therefore, the heater 1 of embodiment 1 can be used to construct a film formation apparatus that can form a thin film of uniform thickness on the surface of a wafer.

[0046] [Base] The base 2 in this example has a disk-like shape. The base 2 has an upper surface 2a and a lower surface 2b. A heating target (not shown) is placed on the upper surface 2a. The lower surface 2b is the opposite surface to the upper surface 2a. A cylindrical body 3 (described later) is attached to the lower surface 2b. The material of the base 2 is, for example, ceramics. Examples of ceramics include aluminum nitride, aluminum oxide, or silicon carbide. The base 2 may be made of a composite material of the above-mentioned ceramics and a metal. Examples of metals include aluminum, an aluminum alloy, copper, or a copper alloy. The material of the base 2 in this example is ceramics.

[0047] A heating element (not shown) is disposed inside the base 2. The heating element is a heat source that heats the heating object. The shape and arrangement of the heating element are not particularly limited. Terminals (not shown) are connected to the heating element. Power lines (not shown) are connected to the terminals. Power is supplied to the heating element from an AC power source (not shown) via the terminals and power lines. The material of the heating element is not particularly limited as long as it can heat the heating object to a desired temperature. The material of each heating element is a metal suitable for resistance heating. The metal is, for example, one selected from the group consisting of stainless steel, nickel, nickel alloy, silver, silver alloy, tungsten, tungsten alloy, molybdenum, molybdenum alloy, chromium, and chromium alloy. The nickel alloy is, for example, nichrome.

[0048] [Cylinder] The cylinder 3 in this example has a cylindrical shape. The cylinder 3 is disposed concentrically with the base 2. In this example, the base 2 and the cylinder 3 are connected so that the center of the cylindrical cylinder 3 and the center of the disk-shaped base 2 are coaxial. The material of the cylinder 3 is ceramic, similar to the material of the base 2. The material of the cylinder 3 and the material of the base 2 may be the same or different.

[0049] The upper end 31 and the lower end 32 of the cylindrical body 3 include flange portions 31a, 32a that are bent outward. In this example, an upper seal member 71 is disposed between the flange portion 31a and the lower surface 2b, and a lower seal member 72 is disposed between the flange portion 32a and the upper surface 41a of a first plate 41 (described later). In this example, the flange portion 32a is fixed to the upper surface 41a of the first plate 41 by a plurality of first fixing screws 57. Each of the first fixing screws 57 penetrates the flange portion 32a and is connected to the first plate 41. The lower seal member 72 is disposed closer to the inner periphery of the flange portion 32a than each of the first fixing screws 57. The upper seal member 71 and the lower seal member 72 seal the interior of the cylindrical body 3. The terminals, power lines, and the like described above are disposed inside the cylindrical body 3. The chamber is typically filled with a corrosive gas. By maintaining the airtightness of the interior of the cylindrical body 3, the terminals, power lines, and the like housed inside the cylindrical body 3 can be isolated from corrosive gases. Unlike this example, the upper seal member 71 may not be provided, and the flange portion 31 a and the lower surface 2 b may be joined by sintering or by screws, for example, so that corrosive gases do not flow between the flange portion 31 a and the lower surface 2 b and into the interior of the cylindrical body 3. Similarly, the lower seal member 72 may not be provided, and the flange portion 32 a and the upper surface 41 a may be joined by sintering or by screws, for example, so that corrosive gases do not flow between the flange portion 32 a and the upper surface 41 a and into the interior of the cylindrical body 3.

[0050] [First Plate and Second Plate] The lower end 32 of the cylindrical body 3 is fixed to the first plate 41. The second plate 42 is disposed below the first plate 41. The first plate 41 and the second plate 42 are connected by second screws 52, which will be described later. The second plate 42 is fixed to the annular mounting base 9 by second fixing screws 58. The number of second fixing screws 58 is three or more. The number of second fixing screws 58 shown in FIGS. 8 to 20 is six. The six second fixing screws 58 will be described later. Although not shown, the number of second fixing screws 58 may be three, four, eight, nine, or twelve. The connection configuration between the first plate 41, the second plate 42, and the mounting base 9 will be described later. Depending on the connection configuration, the first plate 41 and the second plate 42 have screw holes, through holes, etc., which will be described in more detail below.

[0051] In this example, the first plate 41 and the second plate 42 have an annular plate shape. For ease of explanation, the central through-holes of the first plate 41 and the second plate 42 are omitted from illustration in FIGS. 1 to 5 . The above-mentioned power lines and the like are drawn out from the central through-holes of the first plate 41 and the second plate 42 below the lower surface 42b of the second plate 42. In this example, the cylindrical body 3 and the first plate 41 are connected so that the centers of the cylindrical body 3, the annular plate-shaped first plate 41, and the annular plate-shaped second plate 42 are coaxial with each other, and the first plate 41 and the second plate 42 are connected. Unlike this example, the first plate 41 and the second plate 42 may be connected so that the centers of the annular plate-shaped first plate 41 and the annular plate-shaped second plate 42 are different from each other.

[0052] The first plate 41 and the second plate 42 are made of a material such as aluminum, an aluminum alloy, or stainless steel. The material of the second plate 42 and the material of the first plate 41 may be the same or different.

[0053] The first plate 41 has an upper surface 41a and a lower surface 41b. The lower end portion 32 of the cylindrical body 3 is fixed to the upper surface 41a. The lower surface 41b is the opposite surface to the upper surface 41a. The lower surface 41b faces the upper surface 42a of the second plate 42, which will be described later. The second plate 42 has an upper surface 42a and a lower surface 42b. The upper surface 42a faces the lower surface 41b of the first plate 41. The lower surface 42b is the opposite surface to the upper surface 42a. The lower surface 42b is placed on the upper surface 91 of the mounting base 9. A sealing member 6, which will be described later, is arranged between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42.

[0054] The lower surface 41b of the first plate 41 or the upper surface 42a of the second plate 42 may have one or more grooves configured in an annular shape. The number of grooves is the same as the number of seal members 6 described below. In this example, the number of grooves is two. In this example, as shown in FIG. 6 or FIG. 7 , the upper surface 42a of the second plate 42 has a first groove 42i and a second groove 42k. In this example, the first groove 42i and the second groove 42k are concentrically arranged. Unlike this example, the first groove 42i and the second groove 42k may be arranged such that the center of the first groove 42i and the center of the second groove 42k are at different positions. The center of the first groove 42i and the center of the second groove 42k are the center of the envelope circle of the first plate 41 or the center of the envelope circle of the second plate 42. In this example, the center of the first groove 42i and the center of the second groove 42k are the center of the envelope circle of the second plate 42. That is, in this example, the center of the first groove portion 42i and the center of the second groove portion 42k are located at the same position as the center of the envelope circle of the second plate 42. Unlike this example, the center of the first groove portion 42i and the center of the second groove portion 42k may be located at a position different from the center of the envelope circle of the first plate 41 and the center of the envelope circle of the second plate 42.

[0055] In this example, the first groove 42i and the second groove 42k are configured in an annular shape. The diameter of the second groove 42k is larger than the diameter of the first groove 42i. A first seal member 61 (described later) is disposed in the first groove 42i. A second seal member 62 (described later) is disposed in the second groove 42k. The depth D1 of the first groove 42i and the depth D2 of the second groove 42k may be the same as shown in FIG. 6 or may be different as shown in FIG. 7. When the depth D1 of the first groove 42i and the depth D2 of the second groove 42k are different, for example, the depth D2 of the second groove 42k is shallower than the depth D1 of the first groove 42i. The depth D1 of the first groove 42i is, for example, 1 to 5 times, preferably 1 to 4 times, and particularly preferably 1 to 3 times, the depth D2 of the second groove 42k.

[0056] [Sealing Member] The sealing member 6 seals the gap between the first plate 41 and the second plate 42. The sealing member 6 is configured in an annular shape. The number of sealing members 6 is one or more. In this example, the number of sealing members 6 is two. The sealing member 6 includes a first sealing member 61 and a second sealing member 62. The first sealing member 61 and the second sealing member 62 are concentrically arranged. The first sealing member 61 and the second sealing member 62 are configured in an annular shape. The diameter of the second sealing member 62 is larger than the diameter of the first sealing member 61. The first sealing member 61 is disposed in the first groove portion 42i. The second sealing member 62 is disposed in the second groove portion 42k. In other words, the centers of the first sealing member 61 and the second sealing member 62 are the centers of the envelope circles of the second plate 42.

[0057] The thickness T1 of the first seal member 61 and the thickness T2 of the second seal member 62 may be different as shown in FIG. 6 or may be the same as shown in FIG. 7 . The thickness T1 of the first seal member 61 and the thickness T2 of the second seal member 62 here refer to thicknesses when no external force is applied and no load is applied. When no external force is applied and no load is applied, it means that no force other than gravity is applied. When the heater 1 is in use, the first seal member 61 and the second seal member 62 are compressed by the lower surface 41 b of the first plate 41 and the upper surface 42 a of the second plate 42. When no external force is applied and no load is applied, it means that the first seal member 61 and the second seal member 62 are not compressed by the lower surface 41 b of the first plate 41 and the upper surface 42 a of the second plate 42, but are placed on a flat surface, for example.

[0058] As shown in Fig. 6, when the depth D1 of the first groove 42i and the depth D2 of the second groove 42k are the same, the thickness T2 of the second seal member 62 is thicker than the thickness T1 of the first seal member 61. The thickness T2 of the second seal member 62 is, for example, from 1 to 7 times, preferably from 1 to 5 times, and particularly preferably from 1 to 3 times the thickness T1 of the first seal member 61. As shown in Fig. 7, when the depth D2 of the second groove 42k is shallower than the depth D1 of the first groove 42i, the thickness T1 of the first seal member 61 and the thickness T2 of the second seal member 62 may be the same.

[0059] 1 to 5 , each first screw 51 is coupled to the second plate 42 or the first plate 41 so as to press the lower surface 41 b of the first plate 41 or the upper surface 42 a of the second plate 42. Each second screw 52 fastens the first plate 41 and the second plate 42 together so as to pull the lower surface 41 b of the first plate 41 against the upper surface 42 a of the second plate 42. The connection and arrangement of each first screw 51 and each second screw 52 will be described later.

[0060] The number of first screws 51 and the number of second screws 52 are the same. The greater the number of first screws 51 and the number of second screws 52, the easier it is to locally adjust the gap between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42. The fewer the number of first screws 51 and the number of second screws 52, the easier it is to reduce the effort required to adjust the gap between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42. The number of first screws 51 and the number of second screws 52 shown in FIGS. 8 to 20 are three. Although not shown, the number of first screws 51 and the number of second screws 52 may be four, five, six, eight, nine, or twelve.

[0061] The material of each of the first screws 51 and each of the second screws 52 is, for example, stainless steel. The material of the first screws 51 and the material of the second screws 52 may be the same or different. The thread diameter of the first screws 51 and the thread diameter of the second screws 52 may be the same or different.

[0062] 1 to 5, first to fifth examples of connection modes of the first screw 51 and the second screw 52 will be described. In the following description, when referring to the diameter of an inner circumferential surface such as the diameter of a through hole, a threaded hole, a countersunk hole, or a communicating hole, the term "diameter" means the diameter of the inscribed circle of the inner circumferential surface, and when referring to the diameter of an outer circumferential surface such as the diameter of the male thread portion of a screw, the term means the diameter of the envelope circle of the outer circumferential surface.

[0063] 1 satisfies the following requirements (A1) and (B1): (A1) Three or more first screws 51 are engaged with the first screw holes 42c of the second plate 42 so as to press against the lower surface 41b of the first plate 41. (B1) Three or more second screws 52 are inserted into the first through holes 42f of the second plate 42 from below the second plate 42 and engaged with the second screw holes 41d of the first plate 41, thereby fastening the first plate 41 and the second plate 42 together so as to pull the lower surface 41b of the first plate 41 toward the upper surface 42a of the second plate 42.

[0064] The first plate 41 has a plurality of first screw holes 41c and three or more second screw holes 41d. Each of the first screw holes 41c is provided in the upper surface 41a of the first plate 41. The number of the first screw holes 41c is the same as the number of the first fixing screws 57. Each of the first screw holes 41c is coupled to one of the first fixing screws 57. Each of the second screw holes 41d is provided in the lower surface 42b of the second plate 42. Each of the second screw holes 41d is provided inwardly of the first seal member 61 and the mounting base 9. The number of the second screw holes 41d is the same as the number of the second screws 52.

[0065] The second plate 42 has three or more first screw holes 42c, three or more first through holes 42f, and three or more second through holes 42g. Each of the first screw holes 42c is located inside the first seal member 61 and inside the mounting base 9. Each of the first screw holes 42c is located from the upper surface 42a to the lower surface 42b of the second plate 42. The number of the first screw holes 42c is the same as the number of the first screws 51. Each of the first through holes 42f penetrates the upper surface 42a and the lower surface 42b of the second plate 42. The number of the first through holes 42f is the same as the number of the second screws 52. Each of the first through holes 42f is located so that the center of each first through hole 42f and the center of each second screw hole 41d of the first plate 41 are coaxial. That is, each first through hole 42f is located inside the first seal member 61 and the mounting base 9. The diameter of each first through hole 42f is larger than the diameter of the male thread portion 52b of each second screw 52 (described later). Each second through hole 42g penetrates the upper surface 42a and the lower surface 42b of the second plate 42. Each second through hole 42g is located outside the second seal member 62 and in an area overlapping the mounting base 9. The number of second through holes 42g is the same as the number of second fixing screws 58. Each second through hole 42g is composed of a countersunk hole and a communicating hole, arranged in this order from the upper surface 42a to the lower surface 42b of the second plate 42. The diameter of each communicating hole is smaller than the diameter of each countersunk hole. The diameter of each communication hole is larger than the diameter of the male thread portion 58 b of each second fixing screw 58 described below, and smaller than the diameter of the head portion 58 a of each second fixing screw 58 .

[0066] The mounting base 9 has three or more screw holes 93. Each screw hole 93 is provided in the upper surface 91 of the mounting base 9. The number of screw holes 93 is the same as the number of second fixing screws 58. Each screw hole 93 is provided so that the center of each screw hole 93 and the center of each second through hole 42g of the second plate 42 are coaxial. Each screw hole 93 is provided on the outside of the base seal member 75 that seals the gap between the lower surface 42b of the second plate 42 and the upper surface 91 of the mounting base 9.

[0067] The length of each first screw 51 is longer than the thickness of the second plate 42 and shorter than the combined thickness of the first plate 41 and the second plate 42. Each first screw 51 has a head 51a, a male threaded portion 51b, and a tip portion 51c. The head 51a faces the lower surface 42b of the second plate 42. The male threaded portion 51b is coupled to the first screw hole 42c of the second plate 42. The tip portion 51c is in contact with the lower surface 41b of the first plate 41.

[0068] The length of each second screw 52 is longer than the thickness of the second plate 42 and shorter than the combined thickness of the first plate 41 and the second plate 42. Each second screw 52 has a head 52a and a male threaded portion 52b. The head 52a is in contact with the lower surface 42b of the second plate 42. The male threaded portion 52b has a portion that is disposed inside the first through hole 42f of the second plate 42 without being coupled, and a portion that is coupled to the second screw hole 41d of the first plate 41.

[0069] The length of each second fixing screw 58 is longer than the thickness of the second plate 42 but shorter than the combined thickness of the second plate 42 and the mounting base 9. Each second fixing screw 58 has a head 58a and a male threaded portion 58b. The head 58a is disposed in the countersunk hole of the second through hole 42g. The head 58a is in contact with the bottom surface of the countersunk hole. The male threaded portion 58b has a portion that is disposed inside the communicating hole of the second through hole 42g without being coupled, and a portion that is coupled to the threaded hole 93 of the mounting base 9.

[0070] (Second Example) The second example shown in FIG. 2 is the same as the first example, except that the first screws 51 press against the upper surface 42a of the second plate 42 and the second screws 52 are inserted from above the first plate 41. The second example satisfies the following requirements (A2) and (B2): (A2) Three or more first screws 51 are engaged with the third screw holes 41e of the first plate 41 so as to press against the upper surface 42a of the second plate 42. (B2) Three or more second screws 52 are inserted into the first through holes 41f of the first plate 41 from above the first plate 41 and engaged with the second screw holes 42d of the second plate 42, thereby fastening the first plate 41 and the second plate 42 together so as to attract the lower surface 41b of the first plate 41 to the upper surface 42a of the second plate 42.

[0071] The first plate 41 has a plurality of first screw holes 41c identical to the first screw holes 41c in the first example, three or more third screw holes 41e not included in the first example, and three or more first through holes 41f not included in the first example. The first plate 41 does not have the second screw holes 41d in the first example. Each third screw hole 41e is provided outside the second seal member 62. Each third screw hole 41e is provided from the upper surface 41a to the lower surface 41b of the first plate 41. The number of third screw holes 41e is the same as the number of first screws 51. Each first through hole 41f penetrates the upper surface 41a and the lower surface 41b of the first plate 41. Each first through hole 41f is provided outside the second seal member 62. The number of first through holes 41f is the same as the number of second screws 52. The diameter of each first through hole 41 f is larger than the diameter of the male thread portion 52 b of each second screw 52 .

[0072] The second plate 42 has three or more second screw holes 42d, which are not present in the first example, and three or more second through holes 42g, which are the same as the second through holes 42g in the first example. The second plate 42 does not have the first screw holes 42c and the first through holes 42f in the first example. Each second screw hole 42d is provided on the upper surface 42a of the second plate 42. The number of second screw holes 42d is the same as the number of second screws 52. Each second screw hole 42d is provided so that the center of each second screw hole 42d and the center of each first through hole 41f in the first plate 41 are coaxial. In other words, each second screw hole 42d is provided outside the second seal member 62.

[0073] The length of each first screw 51 is longer than the thickness of the first plate 41 and shorter than the combined thickness of the first plate 41 and the second plate 42. Each first screw 51 has a head 51a, a male threaded portion 51b, and a tip portion 51c. The head 51a faces the upper surface 41a of the first plate 41. The male threaded portion 51b is coupled to the third screw hole 41e of the first plate 41. The tip portion 51c contacts the upper surface 42a of the second plate 42.

[0074] The length of each second screw 52 is longer than the thickness of the first plate 41 and shorter than the combined thickness of the first plate 41 and the second plate 42. Each second screw 52 has a head 52a and a male threaded portion 52b. The head 52a is in contact with the upper surface 41a of the first plate 41. The male threaded portion 52b has a portion that is disposed inside the first through hole 41f of the first plate 41 without being coupled, and a portion that is coupled to the second screw hole 42d of the second plate 42.

[0075] (Third Example) The third example shown in FIG. 3 is the same as the first example except that the second screws 52 are inserted from above the first plate 41. The third example is also the same as the second example except that the first screws 51 press against the lower surface 41b of the first plate 41. The third example satisfies the following requirements (A3) and (B3): (A3) Three or more first screws 51 are engaged with the first screw holes 42c of the second plate 42 so as to press against the lower surface 41b of the first plate 41. (B3) Three or more second screws 52 are inserted into the first through holes 41f of the first plate 41 from above the first plate 41 and engaged with the second screw holes 42d of the second plate 42, thereby fastening the first plate 41 and the second plate 42 together so as to draw the lower surface 41b of the first plate 41 toward the upper surface 42a of the second plate 42.

[0076] The first plate 41 has a plurality of first screw holes 41c that are the same as the first screw holes 41c in the first example, and three or more first through holes 41f that are the same as the first through holes 41f in the second example. The first plate 41 does not have the second screw holes 41d in the first example or the third screw holes 41e in the second example.

[0077] The second plate 42 has three or more first screw holes 42c that are the same as the first screw holes 42c in the first example, three or more second screw holes 42d that are the same as the second screw holes 42d in the second example, and three or more second through holes 42g that are the same as the second through holes 42g in the first example. The second plate 42 does not have the first through holes 42f in the first example.

[0078] (Fourth Example) The fourth example shown in FIG. 4 is the same as the first example except that the second fixing screws 58 are inserted from below the mounting base 9. The fourth example satisfies the following requirements (A4) and (B4). (A4) Three or more first screws 51 are engaged with the first screw holes 42c of the second plate 42 so as to press against the lower surface 41b of the first plate 41. (B4) Three or more second screws 52 are inserted into the first through holes 42f of the second plate 42 from below the second plate 42 and engaged with the second screw holes 41d of the first plate 41, thereby fastening the first plate 41 and the second plate 42 together so as to attract the lower surface 41b of the first plate 41 to the upper surface 42a of the second plate 42.

[0079] The second plate 42 has three or more first screw holes 42c that are the same as the first screw holes 42c in the first example, three or more first through holes 42f that are the same as the first through holes 42f in the first example, and three or more third screw holes 42e that are not included in the first example. The second plate 42 does not have the second through holes 42g in the first example. Each third screw hole 42e is provided on the underside 42b of the second plate 42. Each third screw hole 42e is provided inside the base seal member 75 and in an area that overlaps with the mounting base 9. The number of third screw holes 42e is the same as the number of second fixing screws 58.

[0080] The mounting base 9 has three or more first through holes 94, which are not present in the first example. The mounting base 9 does not have the screw holes 93 of the first example. Each first through hole 94 penetrates the upper surface 91 and the lower surface 92 of the mounting base 9. The number of first through holes 94 is the same as the number of second fixing screws 58. Each first through hole 94 is arranged so that the center of each first through hole 94 is coaxial with the center of each third screw hole 42e of the second plate 42. Each first through hole 94 is arranged inside the base seal member 75. The diameter of each first through hole 94 is larger than the diameter of the male thread portion 58b of each second fixing screw 58.

[0081] The length of each second fixing screw 58 is longer than the thickness of the mounting base 9 and shorter than the combined thickness of the second plate 42 and the mounting base 9. Each second fixing screw 58 has a head 58a and a male threaded portion 58b. The head 58a is in contact with the underside 92 of the mounting base 9. The male threaded portion 58b has a portion that is disposed inside the first through-hole 94 of the mounting base 9 without being coupled, and a portion that is coupled to the third screw hole 42e of the second plate 42.

[0082] 5 is the same as the fourth example except that three or more first screw holes 42c of the second plate 42 include first screw holes 42c provided in a region overlapping the mounting base 9, three or more first through holes 42f of the second plate 42 include first through holes 42f provided in a region overlapping the mounting base 9, and the mounting base 9 further has a second through hole 95 and a third through hole 96. The fifth example satisfies the following requirements (A5) and (B5): (A5) Three or more first screws 51 are coupled to the first screw holes 42c of the second plate 42 so as to press against the lower surface 41b of the first plate 41. (B5) Three or more second screws 52 are inserted into the first through holes 42f of the second plate 42 from below the second plate 42 and connected to the second screw holes 41d of the first plate 41, thereby fastening the first plate 41 and the second plate 42 together so as to attract the lower surface 41b of the first plate 41 to the upper surface 42a of the second plate 42.

[0083] The second plate 42 has three or more first screw holes 42c similar to the first screw holes 42c of the fourth example, three or more first through holes 42f similar to the first through holes 42f of the fourth example, and three or more third screw holes 42e similar to the third screw holes 42e of the fourth example. The second plate 42 does not have the second through holes 42g of the first example. The three or more first screw holes 42c include a first screw hole 42c provided inside the first seal member 61 and the mounting base 9, and a first screw hole 42c provided inside the first seal member 61 and in a region overlapping the mounting base 9. The three or more first through holes 42f include a first through hole 42f provided inside the first seal member 61 and the mounting base 9, and a first through hole 42f provided inside the first seal member 61 and in a region overlapping the mounting base 9.

[0084] The mounting base 9 has three or more first through holes 94 identical to the first through holes 94 in the fourth example, as well as second through holes 95 and third through holes 96 not included in the fourth example. The second through holes 95 and third through holes 96 penetrate the upper surface 91 and lower surface 92 of the mounting base 9. The second through holes 95 and third through holes 96 are provided inside the base seal member 75. The second through holes 95 are provided so that the centers of the first screw holes 42c, which are provided inside the first seal member 61 of the second plate 42 and in an area overlapping the mounting base 9, are coaxial with the centers of the second through holes 95. The diameter of the second through holes 95 is larger than the diameter of the male thread portion 51b of the first screw 51. The third through hole 96 is provided so that the center of the first through hole 42f, which is provided inward of the first seal member 61 of the second plate 42 and in an area overlapping the mounting base 9, and the center of the third through hole 96 are coaxial. The diameter of the third through hole 96 is larger than the diameter of the male thread portion 52b of the second screw 52.

[0085] The three or more first screws 51 include one or more first screws 51 that are the same as the first screws 51 of the first example and one or more first screws 51 that are different from the first screw 51 of the first example. The length of the first screws 51 that are different from the first example is longer than the total thickness of the second plate 42 and the mounting base 9, but shorter than the total thickness of the first plate 41, the second plate 42, and the mounting base 9. The first screws 51 that are different from the first example have a head 51a, a male threaded portion 51b, and a tip portion 51c. The head 51a of the first screws 51 that are different from the first example faces the underside 92 of the mounting base 9. The male threaded portion 51b of the first screws 51 that are different from the first example has a portion that is disposed inside the second through-hole 95 of the mounting base 9 without being coupled, and a portion that is coupled to the first screw hole 42c of the second plate 42. Unlike the first example, a tip portion 51 c of the first screw 51 is in contact with the lower surface 41 b of the first plate 41 .

[0086] The three or more second screws 52 include one or more second screws 52 that are the same as the second screws 52 of the first example and one or more second screws 52 that are different from the second screws 52 of the first example. The length of the second screws 52 that are different from the first example is longer than the total thickness of the second plate 42 and the mounting base 9, and shorter than the total thickness of the first plate 41, the second plate 42, and the mounting base 9. The second screws 52 that are different from the first example have a head 52a and a male threaded portion 52b. The head 52a of the second screws 52 that are different from the first example is in contact with the lower surface 92 of the mounting base 9. The male threaded portion 52b of the second screws 52 that are different from the first example has a portion that is disposed in the third through-hole 96 of the mounting base 9 without being coupled, a portion that is disposed in the first through-hole 42f of the second plate 42 without being coupled, and a portion that is coupled to the second screw hole 41d of the first plate 41.

[0087] [Arrangement] First to thirteenth examples of arrangements of the first screws 51 and the second screws 52 will be described with reference to FIGS. 8 to 20 . FIGS. 8 to 20 are perspective views of the first plate 41 from above. For ease of explanation, the first fixing screws 57, the first seal member 61, the second seal member 62, the first groove 42i, the second groove 42k, and the mounting base 9 are omitted from FIGS. 8 to 20 . For ease of explanation, the first screws 51, the second screws 52, and the second fixing screws 58 are indicated by hatched circles in FIGS. 8 to 20 . In FIGS. 8 to 20 , the six second fixing screws 58 are arranged at equal intervals on the circumference of a reference circle Cr centered on the center a of the envelope circle of the first plate 41. "Equal intervals" does not necessarily mean strict spacing, but refers to being substantially equal. "Substantially equal intervals" also includes the case where all of the above-mentioned spacing distances are the same. The following equal intervals also have the same meaning as above. The six second set screws 58 are arranged at the 1 o'clock position, the 3 o'clock position, the 5 o'clock position, the 7 o'clock position, the 9 o'clock position, and the 11 o'clock position, with the clock position being 12 o'clock from the center a upward in the figure. In Figures 8 to 20, a circle passing through the center of the envelope circle of the male thread portion 51 b of each first screw 51, a circle passing through the center of the envelope circle of the male thread portion 52 b of each second screw 52, ​​and a circle passing through the center of the envelope circle of the male thread portion 58 b of each second set screw 58 are shown by two-dot chain lines, with the center a as the center.

[0088] (First Example) In the first example shown in FIG. 8 , three first screws 51 are arranged on the circumference of a first circle C1, and three second screws 52 are arranged on the circumference of a second circle C2. The first circle C1 is a circle centered at center a, and the second circle C2 is a circle centered at center a. "Arranged on the circumference of a circle" does not have a strict meaning, but refers to being arranged substantially on the circumference of a circle. "Arranged substantially on the circumference of a circle" includes, for example, cases where the male thread portion 51b of each first screw 51 is arranged in a position that inscribes, overlaps, or circumscribes the first circle C1. Of course, "arranged substantially on the circumference of a circle" also includes cases where the center of each first screw 51 is arranged on the circumference of the first circle C1.

[0089] The first circle C1, the second circle C2, and the reference circle Cr are the same circle. That is, the three first screws 51, the three second screws 52, and the six second fixing screws 58 are arranged on the circumference of the same circle. The three first screws 51 are arranged at equal intervals on the circumference of the first circle C1. The three second screws 52 are arranged at equal intervals on the circumference of the second circle C2.

[0090] The three first screws 51 are disposed substantially at the 12 o'clock position, substantially at the 4 o'clock position, and substantially at the 8 o'clock position. The three second screws 52 are disposed substantially at the 12 o'clock position, substantially at the 4 o'clock position, and substantially at the 8 o'clock position. The first screws 51 and second screws 52 at each position are adjacent to each other in a direction along the axis of the center a.

[0091] (Second Example) The second example shown in Figure 9 is the same as the first example, except that the positions of the three first screws 51 are closer to the center a than the positions of the three second screws 52. The first circle C1 and the second circle C2 are concentric circles with different radii. The radius of the first circle C1 is smaller than the radius of the second circle C2. The three first screws 51 and the six second fixing screws 58 are arranged on the circumference of different circles.

[0092] (Third Example) The third example shown in Figure 10 is the same as the first example, except that the positions of the three second screws 52 are closer to the center a than the positions of the three first screws 51. The first circle C1 and the second circle C2 are concentric circles with different radii. The radius of the second circle C2 is smaller than the radius of the first circle C1. The three second screws 52 and the six second fixing screws 58 are arranged on the circumference of different circles.

[0093] 11 is the same as the first example except for the positions of the three second screws 52 in the direction around the axis of the center a. The three second screws 52 are arranged at the 2 o'clock position, the 6 o'clock position, and the 10 o'clock position. Each first screw 51 and each second screw 52 is arranged such that each second fixing screw 58 is sandwiched between each first screw 51 and each second screw 52.

[0094] (Fifth Example) The fifth example shown in Figure 12 is the same as the fourth example, except that the positions of the three first screws 51 are closer to the center a than the positions of the three second screws 52. The first circle C1 and the second circle C2 are concentric circles with different radii. The radius of the first circle C1 is smaller than the radius of the second circle C2. The three first screws 51 and the six second fixing screws 58 are arranged on the circumference of different circles.

[0095] (Sixth Example) The sixth example shown in Figure 13 is the same as the fourth example, except that the positions of the three second screws 52 are closer to the center a than the positions of the three first screws 51. The first circle C1 and the second circle C2 are concentric circles with different radii. The radius of the second circle C2 is smaller than the radius of the first circle C1. The three second screws 52 and the six second fixing screws 58 are arranged on the circumference of different circles.

[0096] 14 is the same as the first example except that the positions of the three first screws 51 and the three second screws 52 are closer to the center a than the six second fixing screws 58. The radii of the first circle C1 and the second circle C2 in this example are smaller than the radii of the first circle C1 and the second circle C2 in the first example.

[0097] (Eighth Example) In the eighth example shown in Figure 15, the three second screws 52 are positioned closer to the center a than the six second fixing screws 58, and the three first screws 51 are positioned closer to the center a than the three second screws 52. The first circle C1 and the second circle C2 are concentric circles with different radii. In this example, the radius of the first circle C1 is smaller than the radius of the second circle C2. The three first screws 51 are positioned at the 1 o'clock position, the 5 o'clock position, and the 9 o'clock position. The three second screws 52 are positioned at the 1 o'clock position, the 5 o'clock position, and the 9 o'clock position.

[0098] Although not shown in the drawings, unlike this example, the three first screws 51 may be positioned closer to the center a than the six second fixing screws 58, and the three second screws 52 may be positioned closer to the center a than the three first screws 51. In other words, the radius of the second circle C2 may be smaller than the radius of the first circle C1.

[0099] 16 is the same as the seventh example except for the positions of the three first screws 51 in the direction around the axis of the center a. The three first screws 51 are arranged at the 2 o'clock position, the 6 o'clock position, and the 10 o'clock position.

[0100] (Tenth Example) The tenth example shown in FIG. 17 is the same as the first example, except that one of the three first screws 51 is located closer to the center a than the remaining two first screws 51, and one of the three second screws 52 is located closer to the center a than the remaining two second screws 52. One first screw 51 and one second screw 52 are arranged on the circumference of a fourth circle C4. The remaining two first screws 51 and two second screws 52 are arranged on the circumference of a fifth circle C5. The fourth circle C4 and the fifth circle C5 are circles centered on the center a. The fourth circle C4 and the fifth circle C5 are concentric circles with different radii. The radius of the fourth circle C4 is smaller than the radius of the fifth circle C5. The fifth circle C5 and the reference circle Cr are the same circle. The first screw 51 and the second screw 52 on the circumference of the fourth circle C4 are positioned at the 12 o'clock position. The two first screws 51 on the circumference of the fifth circle C5 are positioned at the 4 o'clock position and the 8 o'clock position. In other words, the first screw 51 and the second screw 52 positioned at the 12 o'clock position are closer to the center a than the first screw 51 and the second screw 52 positioned at the 4 o'clock position and the first screw 51 and the second screw 52 positioned at the 8 o'clock position.

[0101] Unlike this example, although not shown in the figure, the first screw 51 and the second screw 52 located at the 12 o'clock position are arranged on the same circumference as the six second fixing screws 58, and the first screw 51 and the second screw 52 located at the 4 o'clock position and the first screw 51 and the second screw 52 located at the 8 o'clock position may be located closer to the center a than the first screw 51 and the second screw 52 located at the 12 o'clock position.

[0102] (Eleventh Example) The eleventh example shown in FIG. 18 is the same as the first example, except that the three first screws 51 are not equally spaced around the first circle C1 and the three second screws 52 are not equally spaced around the second circle C2. The three first screws 51 are arranged such that, when lines are drawn to connect the centers of adjacent first screws 51 in a direction around the axis of the center a, the center a is located within the area enclosed by the three lines. The three first screws 51 are arranged at positions between 4 and 5 o'clock, between 8 and 9 o'clock, and at the 12 o'clock position. The three second screws 52 are arranged such that, when lines are drawn to connect the centers of adjacent second screws 52 in a direction around the axis of the center a, the center a is located within the area enclosed by the three lines. The three second screws 52 are arranged at positions between 4 and 5 o'clock, between 9 and 10 o'clock, and at the 12 o'clock position.

[0103] (Twelfth Example) The twelfth example shown in FIG. 19 is the same as the first example, except that the three first screws 51 are not evenly spaced around the first circle C1, the three second screws 52 are closer to the center a than the three first screws 51, and the three second screws 52 are not evenly spaced around the second circle C2. The first circle C1 and the second circle C2 are concentric circles with different radii. The radius of the second circle C2 is smaller than the radius of the first circle C1. The three first screws 51 are arranged so that when lines are drawn to connect the centers of adjacent first screws 51 in a direction around the axis of the center a, the center a is located within the area enclosed by the three straight lines. The first screws 51 are arranged at positions between 4 and 5 o'clock, between 6 and 7 o'clock, and between 11 and 12 o'clock. The three second screws 52 are arranged so that when lines are drawn to connect the centers of adjacent second screws 52 in a direction around the axis of center a, center a is located in an area surrounded by the three lines. The second screws 52 are arranged at positions between 4 and 5 o'clock, between 6 and 7 o'clock, and between 11 and 12 o'clock.

[0104] (Thirteenth Example) The thirteenth example shown in FIG. 20 is the same as the first example, mainly except that one of the three first screws 51 is located closer to the center a than the remaining two first screws 51, and two of the three second screws 52 are located closer to the center a than the remaining second screw 52. One first screw 51 is arranged on the circumference of a sixth circle C6. The remaining two first screws 51 are arranged on the circumference of a seventh circle C7. Two second screws 52 are arranged on the circumference of an eighth circle C8. The remaining second screw 52 is arranged on the circumference of the seventh circle C7. The sixth circle C6, the seventh circle C7, and the eighth circle C8 are circles centered at the center a. The sixth circle C6, the seventh circle C7, and the eighth circle C8 are concentric circles with different radii. The radius of the eighth circle C8 is smaller than the radius of the sixth circle C6, which is smaller than the radius of the seventh circle C7. The seventh circle C7 and the reference circle Cr are the same circle.

[0105] With one first screw 51 on the circumference of the sixth circle C6 and two first screws 51 on the circumference of the seventh circle C7, the three first screws 51 are arranged such that when lines are drawn to connect the centers of adjacent first screws 51 in a direction around the axis of the center a, the center a is located in an area surrounded by the three straight lines. The one first screw 51 on the circumference of the sixth circle C6, which is closer to the center a, is located between 10 o'clock and 11 o'clock. The two first screws 51 on the circumference of the seventh circle C7, which is farther from the center a, are located between 3 o'clock and 4 o'clock and between 6 o'clock and 7 o'clock. With one second screw 52 on the circumference of the seventh circle C7 and two second screws 52 on the circumference of the eighth circle C8, the three second screws 52 are arranged such that when lines are drawn to connect the centers of adjacent second screws 52 in a direction around the axis of the center a, the center a is located in an area surrounded by the three straight lines. The two second screws 52 on the circumference of the eighth circle C8, which is closer to the center a, are located between 2 o'clock and 3 o'clock and between 7 o'clock and 8 o'clock. The one second screw 52 on the circumference of the seventh circle C7, which is farther from the center a, is located between 11 o'clock and 12 o'clock.

[0106] Although it depends on the thickness of the sealing member 6, the distance between the periphery of the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42 can be adjusted within a range of 0 mm to 1 mm by using the first screws 51 and the second screws 52. Although it also depends on the length of the cylindrical body 3 and the diameter of the base 2, by adjusting the distance within the above range, the movable range of the periphery of the upper surface 2a of the base 2 can be set to, for example, 0 mm to 2 mm.

[0107] [Example of Gap Adjustment] An example of adjusting the gap between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42 will be described. The description here will be made for the first example arrangement shown in FIG. 8 . For example, to widen the gap between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42, which corresponds to the 12 o'clock position, by 0.5 mm, the following procedure is performed. The first screw 51 and the second screw 52 located at the 12 o'clock position, the first screw 51 and the second screw 52 located at the 4 o'clock position, and the first screw 51 and the second screw 52 located at the 8 o'clock position are rotated. By rotating the first screw 51 and the second screw 52 located at the 4 o'clock position, the gap between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42, which corresponds to the 4 o'clock position, is widened by 0.3 mm. Rotation of the first screw 51 and the second screw 52 located at the 8 o'clock position widens the gap between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42, which corresponds to the 8 o'clock position, by 0.3 mm. The gap corresponding to the 4 o'clock position can be widened by 0.3 mm, and the gap corresponding to the 8 o'clock position can be widened by 0.3 mm, and rotation of the first screw 51 and the second screw 52 located at the 12 o'clock position can widen the gap corresponding to the 12 o'clock position by 0.5 mm.

[0108] <<Embodiment 2>> [Heater] A heater 1 of embodiment 2 will be described with reference to Figures 21 and 22. The heater 1 of embodiment 2 is the same as the heater 1 of embodiment 1, except that it further includes three or more third screws 53 that regulate the distance between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42 to a predetermined value or less. The following description will focus on the differences from embodiment 1. Description of the same configuration and effects as embodiment 1 will be omitted. Figure 21 is based on a second example of the connection configuration in the heater 1 of embodiment 1.

[0109] [First Plate / Second Plate] The first plate 41 has a plurality of first screw holes 41c identical to the first screw holes 41c of the second example, three or more third screw holes 41e identical to the third screw holes 41e of the second example, three or more first through holes 41f identical to the first through holes 41f of the second example, and three or more second through holes 41g not included in the second example. Each second through hole 41g penetrates the upper surface 41a and the lower surface 41b of the first plate 41. Each second through hole 41g is located outside the second seal member 62. The number of second through holes 41g is the same as the number of third screws 53. The diameter of each second through hole 41g is larger than the diameter of the shank 53b of each third screw 53.

[0110] The second plate 42 has three or more second screw holes 42d, which are the same as the second screw holes 42d in the second example, three or more second through holes 42g, which are the same as the second through holes 42g in the second example, and three or more third screw holes 42e, which are not provided in the second example. Each third screw hole 42e is provided on the upper surface 42a of the second plate 42. Each third screw hole 42e is provided so that the center of the third screw hole 42e is coaxial with the center of the second through hole 41g in the first plate 41. In other words, each third screw hole 42e is provided outside the second seal member 62. The number of second screw holes 42d is the same as the number of third screws 53.

[0111] [Third Screws] The number of third screws 53 is the same as the number of either the first screws 51 or the second screws 52. In this example, the number of third screws 53 is the same as the number of first screws 51 or the number of second screws 52. The number of third screws 53 shown in FIG. 22 is three. Each third screw 53 has a head 53a facing the upper surface 41a of the first plate 41, a shank 53b that is disposed inside the second through-hole 41g of the first plate 41 without being coupled thereto, and a male threaded portion 53c that is coupled to the second plate 42. By adjusting the distance between the head 53a and the upper surface 41a of the first plate 41, the maximum distance between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42 can be adjusted. When the first plate 41 is moved within a predetermined range in a direction away from the second plate 42, the upper surface 41a of the first plate 41 comes into contact with the head 53a of the third screw 53, preventing the first plate 41 from moving above the head 53a. This prevents the lower surface 41b of the first plate 41 from moving too far away from the upper surface 42a of the second plate 42. The diameter of the male thread portion 53c is smaller than the diameter of the shaft portion 53b. The end face of the shaft portion 53b is in contact with the upper surface 42a of the second plate 42.

[0112] The example shown in FIG. 22 is the same as the first example of the arrangement of the heater 1 of embodiment 1, except that a third screw 53 is further arranged. The three third screws 53 are arranged on the circumference of a third circle C3. The third circle C3 is a circle centered at center a. The third circle C3 is the same circle as at least one of the first circle C1 and the second circle C2. For example, if the first circle C1 and the second circle C2 are concentric circles with different radii, the third circle C3 is the same circle as the first circle C1 or the second circle C2. If the first circle C1 and the second circle C2 are the same circle as in this example, the third circle C3 is the same circle as both the first circle C1 and the second circle C2. The three third screws 53 are arranged on the circumference of the same circle as the three first screws 51, the three second screws 52, and the six second fixing screws 58. The three third screws 53 are arranged at equal intervals on the circumference of the third circle C3, at the 2 o'clock position, the 6 o'clock position, and the 10 o'clock position.

[0113] Unlike this example, although not shown in the drawings, the three third screws 53 may be disposed substantially at the 12 o'clock position, the 4 o'clock position, and the 8 o'clock position. The three third screws 53 do not have to be disposed at equal intervals around the circumference of the third circle C3. One or two of the three third screws 53 may be disposed closer to the center a than the remaining two or one third screws 53.

[0114] In this example, the third screw 53 is inserted from above the first plate 41. However, unlike this example, it may be inserted from below the second plate 42. In this case, a through hole corresponding to the second through hole 41g is provided in the second plate 42, and a screw hole corresponding to the third screw hole 42e is provided in the first plate 41. The head 53a faces the lower surface 42b of the second plate 42. By adjusting the distance between the head 53a and the lower surface 42b of the second plate 42, the maximum distance between the lower surface 41b of the first plate 41 and the upper surface 42a of the second plate 42 can be adjusted. When the first plate 41 is moved within a predetermined range in a direction away from the second plate 42, the head 53a of the third screw 53 comes into contact with the lower surface 42b of the second plate 42. This prevents the lower surface 41b of the first plate 41 from moving too far away from the upper surface 42a of the second plate 42.

[0115] The material of the third screw 53 may be the same as or different from the material of the first screw 51 or the material of the second screw 52. The material of the third screw 53 is, for example, stainless steel.

[0116] Third Embodiment [Heater] The heater 1 of the third embodiment will be described with reference to Figures 23 and 24. The heater 1 of the third embodiment is the same as the heater 1 of the first embodiment, mainly except that it further includes pins 55. The following description will focus on the differences from the first embodiment. Description of the same configuration and effects as the first embodiment will be omitted. Figures 23 and 24 are based on a second example of the connection configuration of the heater 1 of the first embodiment.

[0117] [Pin] The pin 55 is sandwiched between the lower surface 41b of the first plate 41 or the upper surface 42a of the second plate 42 and each of the three or more first screws 51. The first screws 51 press the pin 55, and the pressed pin 55 presses the lower surface 41b of the first plate 41 or the upper surface 42a of the second plate 42. Because the pin 55 directly presses the lower surface 41b of the first plate 41 or the upper surface 42a of the second plate 42, the lower surface 41b of the first plate 41 or the upper surface 42a of the second plate 42 is less likely to be worn down compared to when the first screws 51 directly press the lower surface 41b of the first plate 41 or the upper surface 42a of the second plate 42. In this example, the pin 55 is sandwiched between the upper surface 42a of the second plate 42 and each of the three or more first screws 51. The diameter of the pin 55 may be the same as the diameter of the male thread portion 51b of the first screw 51, or may be larger or smaller than the diameter of the male thread portion 51b. When the force acting on the pin 55 by the first screw 51 is constant, if the diameter of the pin 55 is equal to or larger than the diameter of the male thread portion 51b, the pressure acting on the upper surface 42a of the second plate 42 can be reduced compared to when the diameter of the pin 55 is smaller than the diameter of the male thread portion 51b. In this example, the diameter of the pin 55 is larger than the diameter of the male thread portion 51b. The pin 55 is made of the same material as the first screw 51.

[0118] [First Plate and Second Plate] The first plate 41 shown in Fig. 23 differs from the first plate 41 of the second example in that it further includes a hole 41h. The diameter of the hole 41h is larger than the diameter of the third screw hole 41e of the first plate 41. The hole 41h is connected to the third screw hole 41e of the first plate 41. The hole 41h is provided so that the center of the hole 41h and the center of the third screw hole 41e are coaxial. If the diameter of the pin 55 is smaller than the diameter of the male thread portion 51b of the first screw 51, the first plate 41 does not need to include the hole 41h.

[0119] The second plate 42 shown in Figure 23 differs from the second plate 42 of the second example in that it has a recess 42h in its upper surface 42a in which a pin 55 is disposed. The bottom surface of the recess 42h is aligned with the tip surface of the pin 55. If the tip surface of the pin 55 is configured as a convex curved surface, the bottom surface of the recess 42h is also configured as a curved surface. The second plate 42 shown in Figure 24 does not have the recess 42h in its upper surface 42a. The portion of the upper surface 42a of the second plate 42 facing the pin 55 may be configured as a flat surface.

[0120] The present invention is not limited to these examples, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0121] REFERENCE SIGNS LIST 1 heater 2 base, 2a upper surface, 2b lower surface 3 cylinder 31 upper end, 31a flange portion 32 lower end, 32a flange portion 4 plate 41 first plate, 41a upper surface, 41b lower surface 41c first screw hole, 41d second screw hole, 41e third screw hole 41f first through hole, 41g second through hole, 41h hole portion 42 second plate, 42a upper surface, 42b lower surface 42c first screw hole, 42d second screw hole, 42e third screw hole 42f first through hole, 42g second through hole, 42h recess 42i first groove portion, 42k second groove portion 51 first screw, 51a head portion, 51b male thread portion, 51c tip portion 52 second screw, 52a Head, 52b Male thread portion 53 Third screw, 53a Head, 53b Shank, 53c Male thread portion 55 Pin, 57 First fixing screw 58 Second fixing screw, 58a Head, 58b Male thread portion 6 Seal member, 61 First sealing member, 62 Second sealing member 71 Upper sealing member, 72 Lower sealing member 75 Base sealing member 9 Mounting base, 91 Upper surface, 92 Lower surface 93 Screw hole 94 First through hole, 95 Second through hole, 96 Third through hole A Area D1, D2 Depth, T1, T2 Thickness a Center C1 First circle, C2 Second circle, C3 Third circle C4 Fourth circle, C5 Fifth circle, C6 Sixth circle C7 Seventh circle, C8 Eighth circle, Cr Reference circle

Claims

1. A base on which a heating object is placed; and A cylinder fixed to the lower surface of the base; A first plate to which a lower end of the cylindrical body is fixed; a second plate disposed below the first plate and fixed to a mounting base; one or more sealing members configured in an annular shape and sealing between the lower surface of the first plate and the upper surface of the second plate; three or more first screws coupled to the screw holes of the second plate or the screw holes of the first plate so as to press the lower surface of the first plate or the upper surface of the second plate; and three or more second screws fastening the first plate and the second plate together so as to draw the lower surface of the first plate to the upper surface of the second plate. heater.

2. a lower surface of the first plate or an upper surface of the second plate has a first groove portion and a second groove portion that are provided in an annular shape, The diameter of the second groove portion is larger than the diameter of the first groove portion, The depth of the first groove portion and the depth of the second groove portion are the same depth, the number of the one or more seal members is two, i.e., a first seal member and a second seal member; The thickness of the second seal member when unloaded is greater than the thickness of the first seal member when unloaded, The first seal member is disposed in the first groove portion, The heater according to claim 1 , wherein the second seal member is disposed in the second groove portion.

3. a lower surface of the first plate or an upper surface of the second plate has a first groove portion and a second groove portion that are provided in an annular shape, The diameter of the second groove portion is larger than the diameter of the first groove portion, The depth of the second groove portion is shallower than the depth of the first groove portion, the number of the one or more seal members is two, i.e., a first seal member and a second seal member; The thickness of the first seal member when no load is applied is the same as the thickness of the second seal member when no load is applied, The first seal member is disposed in the first groove portion, The heater according to claim 1 , wherein the second seal member is disposed in the second groove portion.

4. 4. The heater according to claim 2, wherein the first groove and the second groove are provided concentrically.

5. The heater according to claim 4 , wherein a center of the first groove portion and a center of the second groove portion are the center of an envelope circle of the first plate or the center of an envelope circle of the second plate.

6. The heater according to claim 1 , wherein a number of the three or more first screws is equal to a number of the three or more second screws.

7. the three or more first screws are arranged on the circumference of a first circle centered on the center of the envelope circle of the first plate, The heater according to claim 1 , wherein the three or more second screws are arranged on a circumference of a second circle centered on a center of the envelope circle of the first plate.

8. The heater of claim 7 , wherein the first circle and the second circle are the same circle.

9. The heater according to claim 7 , wherein the first circle and the second circle are concentric circles having different radii.

10. The three or more first screws are equally spaced around the circumference of the first circle, The heater of claim 7 , wherein the three or more second screws are equally spaced around the circumference of the second circle.

11. 4. The heater according to claim 1, further comprising three or more third screws that regulate a distance between the lower surface of the first plate and the upper surface of the second plate to a predetermined value or less.

12. A heater as described in claim 11, wherein the number of the three or more third screws is the same as the number of the three or more first screws and the number of the three or more second screws.

13. Each of the three or more third screws is a head portion facing an upper surface of the first plate; A shaft portion penetrating the first plate; and a male thread coupled to the second plate.

14. The heater according to claim 11 , wherein the three or more third screws are arranged on the circumference of a third circle centered on the center of the envelope circle of the first plate.

15. The three or more first screws are arranged on the circumference of a first circle centered on the center of the envelope circle of the first plate, the three or more second screws are arranged on the circumference of a second circle centered on the center of the envelope circle of the first plate, The heater of claim 14 , wherein the third circle is the same circle as at least one of the first circle and the second circle.

16. The heater of claim 14 , wherein the three or more third screws are equally spaced around the circumference of the third circle.

17. The heater of claim 1 , further comprising a pin sandwiched between a lower surface of the first plate or an upper surface of the second plate and each of the three or more first screws.

18. 18. The heater of claim 17, wherein the lower surface of the first plate or the upper surface of the second plate has a recess in which the pin is disposed.