Electrostatic chuck heater and film forming device

Abstract

Provided is an electrostatic chuck heater capable of uniformizing the deformation of a wafer around a lift pin hole. This electrostatic chuck heater is used for a film forming apparatus. The electrostatic chuck heater comprises: a ceramic plate having a first surface on which a wafer to be film-formed is placed, and a second surface facing the first surface, and having an ESC electrode and a heater electrode embedded therein; a ceramic shaft attached to the second surface of the ceramic plate, and having an internal space for housing an ESC rod connected to the ESC electrode and a heater rod connected to the heater electrode; a plurality of lift pin holes penetrating from the first surface to the second surface of the ceramic plate; and a plurality of protrusions which are arranged on the first surface of the ceramic plate at equal intervals and rotationally symmetric with respect to the respective central axes of the lift pin holes.

Description

[Technical field]

[0001] The present invention relates to an electrostatic chuck heater and a film forming apparatus. [Background technology]

[0002] In a film deposition apparatus for a semiconductor manufacturing process, a ceramic heater is used as a support stage for uniformly controlling the temperature of a wafer. Also, a ceramic heater equipped with an electrostatic chuck for stable chucking of the wafer is known.

[0003] Patent Document 1 (Japanese Patent No. 6948458) discloses a Johnson-Rahbek type electrostatic chuck heater used to form a conductive film on a wafer. This electrostatic chuck heater comprises a disk-shaped ceramic base equipped with an electrostatic electrode and a resistance heating element, and a hollow shaft attached to the ceramic base. A plurality of protrusions and convex portions that can come into contact with the wafer are embossed in predetermined areas on the surface of this ceramic base, and it is said that these protrusions and convex portions (hereinafter collectively referred to as protrusions) can stably chuck the wafer.

[0004] Various other susceptors are known that have multiple embossed protrusions on their surface (see, for example, Patent Document 2 (Japanese Patent No. 6792455, particularly Figure 3A), Patent Document 3 (JP Patent Publication No. 2020-191450, particularly Figure 3), and Patent Document 4 (Japanese Patent No. 6818351, particularly Figure 7)). As disclosed in these documents, the multiple embossed protrusions on the surface of conventional susceptors were generally arranged symmetrically and equally spaced with respect to the central axis of the wafer placed on the susceptor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6948458 [Patent Document 2] Patent No. 6792455 [Patent Document 3] JP 2020-191450 A [Patent Document 4] Patent No. 6818351 Summary of the Invention

[0006] As described above, by arranging the multiple embossed protrusions at equal intervals on the surface of the susceptor, stable chucking of the wafer is possible in each region, which contributes to uniformity of the film thickness formed on the wafer. In addition, the presence of the protrusions can reduce the contact area between the susceptor surface and the wafer, which results in a reduction in contamination caused by contact with the susceptor and an optimization of the adhesion force of the wafer to the susceptor, making it easier to remove the wafer.

[0007] However, as disclosed in Patent Documents 2 to 4, in addition to embossed protrusions, lift pin holes may be provided on the plate portion of the susceptor on which the wafer is placed. The lift pin holes are holes used to insert lift pins for lifting the wafer from below after processing such as film formation, and a plurality of lift pin holes (e.g., three or four) are provided at positions spaced apart from each other. In this case, as shown in Figures 5 and 6, protrusions 118 on the surface of plate 112 are aligned with the central axis C of plate 112. P In the conventional layout, the projections 118 are arranged symmetrically and equally spaced about the central axis C of the lift pin hole 116. H5 and 6, the plurality of protrusions 118 around the lift pin hole 116 are arranged asymmetrically or non-uniformly with respect to the lift pin hole 116, which makes the electrostatic adsorption unstable and increases the distortion of the wafer W supported only by the protrusions 118 while being strongly electrostatically adsorbed to the plate 112. In this case, the wafer W is not distorted concentrically with respect to the lift pin hole 116, and the distortion is non-uniform. If the distortion of the wafer W is non-uniform, the thickness of the film formed on the wafer W may be non-uniform.

[0008] The present inventors have now discovered that by arranging multiple protrusions on a ceramic plate at equal intervals and rotationally symmetrical about the central axes of the lift pin holes, it is possible to provide an electrostatic chuck heater that can uniformly reduce distortion of a wafer around the lift pin holes.

[0009] Therefore, an object of the present invention is to provide an electrostatic chuck heater capable of uniformly distorting the wafer around the lift pin holes.

[0010] According to the present invention, the following aspects are provided. [Aspect 1] An electrostatic chuck heater for use in a film forming apparatus, comprising: a ceramic plate having a first surface on which a wafer to be formed is placed and a second surface opposite to the first surface, and having ESC electrodes and a heater electrode built therein; a ceramic shaft attached to the second surface of the ceramic plate and having an internal space for accommodating ESC rods connected to the ESC electrodes and heater rods connected to the heater electrode; a plurality of lift pin holes extending from the first surface to the second surface of the ceramic plate; a plurality of protrusions disposed on a first surface of the ceramic plate at equal intervals and rotationally symmetrical with respect to a central axis of each of the lift pin holes; An electrostatic chuck heater comprising: [Aspect 2] 2. The electrostatic chuck heater of claim 1, wherein the plurality of protrusions are arranged asymmetrically with respect to a central axis of the ceramic plate. [Aspect 3] 3. The electrostatic chuck heater according to claim 1 or 2, wherein the plurality of protrusions are arranged according to a regular pattern having a unit shape selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon. [Aspect 4] 4. The electrostatic chuck heater according to aspect 3, wherein the constituent units of the regular pattern have a circumscribed circle diameter of 4 to 30 mm. [Aspect 5] 5. The electrostatic chuck heater according to claim 3 or 4, wherein a constituent unit of the regular pattern is an equilateral triangle. [Aspect 6] 6. The electrostatic chuck heater according to embodiment 5, wherein each side of the equilateral triangle is 4 to 30 mm. [Aspect 7] 7. The electrostatic chuck heater according to claim 5 or 6, wherein the plurality of protrusions are arranged to have three-fold rotational symmetry or six-fold rotational symmetry with respect to the central axis of each of the lift pin holes. [Aspect 8] 8. The electrostatic chuck heater according to any one of aspects 1 to 7, wherein the distance between the central axes of the adjacent protrusions is 4 to 30 mm. [Aspect 9] 9. The electrostatic chuck heater according to any one of aspects 1 to 8, wherein the protrusions have a height of 0.001 to 0.1 mm. [Aspect 10] 10. The electrostatic chuck heater according to any one of aspects 1 to 9, wherein the lift pin hole has a circular shape in a plan view. [Aspect 11] 11. The electrostatic chuck heater according to any one of aspects 1 to 10, wherein the number of the lift pin holes is three or four. [Aspect 12] 12. The electrostatic chuck heater according to any one of aspects 1 to 11, wherein the lift pin holes have a diameter of 1 to 5 mm. [Aspect 13] 13. The electrostatic chuck heater according to any one of aspects 1 to 12, further comprising: the ESC rod and the heater rod in the internal space of the ceramic shaft. [Aspect 14] A film formation apparatus comprising: a film formation chamber; and the electrostatic chuck heater according to any one of aspects 1 to 13 provided in the film formation chamber. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing an example of an electrostatic chuck heater according to the present invention. [Diagram 2] FIG. 1 is a schematic top view showing an example of an electrostatic chuck heater according to the present invention. [Diagram 3] 3 is a schematic cross-sectional view conceptually showing a cross section in the vicinity of a lift pin hole of the electrostatic chuck heater shown in FIG. 2. [Figure 4] FIG. 4 is a schematic top view showing another example of an electrostatic chuck heater according to the present invention. [Diagram 5] FIG. 1 is a schematic top view showing an example of a conventional electrostatic chuck heater. [Figure 6] 6 is a schematic cross-sectional view conceptually showing a cross section in the vicinity of a lift pin hole of the conventional electrostatic chuck heater shown in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The electrostatic chuck heater according to the present invention is used in a film formation apparatus, particularly in a film formation apparatus for a semiconductor manufacturing process. The electrostatic chuck heater functions as a susceptor that chucks a wafer on which a film is to be formed by electrostatic attraction while heating the wafer in the film formation apparatus. Typical examples of film formation apparatuses to which the electrostatic chuck heater can be applied include CVD (chemical vapor deposition) apparatuses (e.g., thermal CVD apparatuses, plasma CVD apparatuses, photo CVD apparatuses, and MOCVD apparatuses) and PVD (physical vapor deposition) apparatuses.

[0013] 1 and 2 show an example of an electrostatic chuck heater. The electrostatic chuck heater 10 shown in FIGS. 1 and 2 includes a ceramic plate 12, a ceramic shaft 14, a plurality of lift pin holes 16, and a plurality of protrusions 18. The ceramic plate 12 has an ESC electrode 20 and a heater electrode 22 built therein. The ceramic plate 12 has a first surface 12a on which a wafer W to be film-formed is placed and a second surface 12b opposite to the first surface 12a, and the ceramic shaft 14 is attached to the second surface 12b. The ceramic shaft 14 has an internal space for accommodating an ESC rod 24 connected to the ESC electrode 20 and a heater rod 26 connected to the heater electrode 22. The lift pin holes 16 are provided so as to penetrate from the first surface 12a to the second surface 12b of the ceramic plate 12. The protrusions 18 are provided on the first surface 12a of the ceramic plate 12 at equal intervals and aligned along the central axis C of each of the lift pin holes 16. H In this manner, the plurality of protrusions 18 on the ceramic plate 12 are arranged at equal intervals and are aligned with the central axis C of each of the lift pin holes 16. H By arranging the lift pin holes 16 in a rotationally symmetrical manner with respect to the lift pin holes 16, the distortion of the wafer W around the lift pin holes 16 can be made uniform.

[0014] That is, as described above, in the conventional susceptor, as shown in FIGS. 5 and 6, the protrusions 118 on the surface of the plate 112 are aligned with the central axis C of the plate 112. PIn this case, the multiple protrusions 118 around the lift pin hole 116 are arranged asymmetrically or unevenly with respect to the lift pin hole 116, which makes the electrostatic attraction unstable and increases the distortion of the wafer W supported only by the protrusions 118 while being strongly electrostatically attracted to the plate 112. In particular, the protrusions 118 are arranged symmetrically and at equal intervals with respect to the central axis C of the lift pin hole 116. H However, since the wafer W does not distort concentrically, the distortion becomes non-uniform, which may result in non-uniform thickness of the film formed on the wafer W. This problem is eliminated or reduced by the electrostatic chuck heater 10 of the present invention. This is because, as shown in FIGS. 2 and 3, the multiple protrusions 18 are arranged at equal intervals and aligned with the central axes C of the lift pin holes 16. H This is because the projections 18 are arranged rotationally symmetrically with respect to the lift pin hole 16, so that the distortion of the wafer W around the lift pin hole 16 is uniformed. That is, the central axis C of the lift pin hole 16 is aligned with the center of a polygon (a regular triangle in FIG. 2) connecting the projections 18 located closest to the lift pin hole 16. H Therefore, the distortion of the wafer W is prevented from occurring along the central axis C of the lift pin hole 16. H As a result, the distortion is uniform in the circumferential direction of the concentric circles. Since the distortion of the wafer W affects the film thickness when a film is formed on the wafer W, the distortion of the wafer W around the lift pin holes 16 is uniformized, thereby making it possible to realize a uniform film thickness. In other words, by using the electrostatic chuck heater 10 according to the present invention in a film forming apparatus, the uniformity of the film thickness formed on the wafer W can be improved.

[0015] The reason why the distortion of the wafer W around the lift pin hole 16 is uniformized and the film thickness can be uniformized is considered to be as follows. First, as a premise, the lift pin hole 16 is a region where the heater electrode 22 does not exist. For this reason, the wafer temperature on the lift pin hole 16 is lower than the wafer temperature in other regions, and as a result, the film thickness during film formation in the region where the wafer temperature has dropped is likely to become a singular point (that is, the film thickness around the lift pin hole 16 is likely to change specifically compared to the stable film thickness in the region away from the lift pin hole 16). In addition, it is assumed that the smaller the distance between the wafer W and the ceramic plate 12, the greater the heat conduction from the ceramic plate 12 and the higher the temperature of the wafer W. In this regard, if the protrusions 18 are arranged non-rotationally symmetrically with respect to the lift pin hole 16 around the lift pin hole 16, which is likely to become a singular point as described above, the distance between the wafer W and the ceramic plate 12 will not be rotationally symmetrical depending on the distortion, and the wafer temperature will become more non-uniform, and as a result, the region of the singular point will expand and the uniformity of the film thickness will be further reduced. When chips are mounted on a wafer W with such reduced uniformity in film thickness, the yield may decrease. In this way, it is believed that the film thickness distribution in the lift pin holes 16 and the surrounding area, which is originally poor, is further deteriorated by the uneven arrangement of the protrusions 18, resulting in a decrease in yield. According to the present invention, such problems are eliminated or reduced as described above.

[0016] The ceramic plate 12 is not particularly limited except for the arrangement of the protrusions 18 on the first surface 12a, and may have the same configuration as a ceramic plate adopted in a known electrostatic chuck heater. A main portion (i.e., a ceramic base) of the ceramic plate 12 other than the ESC electrodes 20 and the heater electrode 22 is preferably made of aluminum nitride from the viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon. A preferable shape of the ceramic plate 12 is a disk shape. However, the planar shape of the disk-shaped ceramic plate 12 does not need to be a perfect circle, and may be an incomplete circle with a part missing, such as an orientation flat. The size of the ceramic plate 12 may be appropriately determined according to the diameter of the wafer W expected to be used, and is not particularly limited, but in the case of a circle, the diameter is typically 150 to 450 mm, for example, about 300 mm.

[0017] The ceramic plate 12 has an ESC electrode 20 and a heater electrode 22 built in or embedded therein. The ESC electrode 20 is an abbreviation of electrostatic chuck (ESC) electrode, and is also called an electrostatic electrode. The ESC electrode 20 is preferably a circular thin-layer electrode having a diameter slightly smaller than that of the ceramic plate 12, and may be, for example, a mesh-like electrode formed by weaving thin metal wires into a sheet shape. The ESC electrode 20 may be used as a plasma electrode. That is, by applying a high frequency to the ESC electrode 20, the ESC electrode 20 can also be used as a plasma electrode, and film formation can also be performed by a plasma CVD process. An ESC rod 24 is connected to the ESC electrode 20 for power supply, and the ESC rod 24 is connected to an external power source (not shown) via the internal space of the ceramic shaft 14. When a voltage is applied by the external power source, the ESC electrode 20 chucks the wafer W placed on the first surface 12a. The chucking force at this time is set to a value when the volume resistivity of aluminum nitride constituting the main part of the ceramic plate 12 is 1×10 8 ~1×10 13Since the resistance is Ωcm, it is the Johnsen-Rahbek force. The heater electrode 22 is not particularly limited, but may be, for example, a conductive coil wired in a single stroke across the entire surface of the ceramic plate 12. Heater rods 26 are connected to both ends of the heater electrode 22 for power supply, and the heater rods 26 are connected to a heater power source (not shown) via the internal space of the ceramic shaft 14. When power is supplied from the heater power source, the heater electrode 22 generates heat and heats the wafer W placed on the first surface 12a. The heater electrode 22 is not limited to a coil, but may be, for example, a ribbon (a long, thin plate) or a mesh.

[0018] The lift pin holes 16 are provided penetrating from the first surface 12a to the second surface 12b of the ceramic plate 12. As described above, the lift pin holes 16 are holes used for inserting lift pins (not shown) for lifting the wafer W from below after film formation. That is, after film formation, a lift pin comes out from the first surface 12a of the ceramic plate 12 through the lift pin holes 16 to lift the wafer W upward, thereby facilitating removal of the wafer W from the electrostatic chuck heater 10.

[0019] The planar shape of the lift pin holes 16 may be any shape, such as a circle or a polygon, but is preferably a circle. The number of lift pin holes 16 provided in the ceramic plate 12 is preferably three or four, and more preferably three. With such a small number of holes, it is possible to secure a large effective area in the ceramic plate 12 while sufficiently securing a fulcrum for lifting the wafer W by the lift pins (not shown). The diameter of the lift pin holes 16 is not particularly limited, but is preferably 1 to 5 mm, more preferably 2 to 4 mm, and further preferably 2 to 3 mm.

[0020] The protrusions 18 are provided on the first surface 12a of the ceramic plate 12 at equal intervals and aligned with the central axes C of the lift pin holes 16. HTherefore, unlike the layout generally adopted in the prior art (see, for example, FIG. 5), the protrusions 18 are arranged so as to be rotationally symmetrical about the central axis C of the ceramic plate 12. P The projections 18 may be arranged asymmetrically with respect to the ceramic plate 12. The shape of each projection 18 is not particularly limited, but is preferably cylindrical. The diameter of each projection 18 is not particularly limited, but is preferably 0.1 to 8 mm, more preferably 0.5 to 5 mm, even more preferably 0.5 to 4 mm, and particularly preferably 0.70 to 2.54 mm. The projections 18 are preferably integrally formed with the ceramic plate 12 by embossing or the like. Therefore, like the ceramic plate 12, the projections 18 are preferably made of aluminum nitride. The height of the projections 18 is not particularly limited, but is preferably 0.001 to 0.1 mm, more preferably 0.005 to 0.08 mm, even more preferably 0.01 to 0.05 mm, and particularly preferably 0.01 to 0.03 mm. The distance between the central axes of adjacent projections 18 is preferably 4 to 30 mm, more preferably 5 to 26 mm, even more preferably 7 to 26 mm, and particularly preferably 7 to 15 mm.

[0021] The plurality of protrusions 18 are preferably arranged according to (or to form) a regular pattern having one selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon as a constituent unit. That is, the centers of the plurality of protrusions 18 are preferably arranged so as to be located on a virtual line constituting a regular pattern in which a plurality of the above constituent units are repeated (for example, at a vertex in the case of a polygon). In other words, it is preferable that a virtual figure drawn by connecting the centers of adjacent protrusions 18 forms a regular pattern having one selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon as a constituent unit. For example, in the electrostatic chuck heater 10 shown in FIG. 2, a virtual figure drawn by connecting the centers of adjacent protrusions 18 is an equilateral triangle. In the electrostatic chuck heater 10' shown in FIG. 4, a virtual figure drawn by connecting the centers of adjacent protrusions 18 is a regular hexagon. In particular, in terms of facilitating the arrangement of the protrusions 18 at equal intervals across the entire first surface 12a, the constituent units of the regular pattern are more preferably squares, equilateral triangles, or regular hexagons, even more preferably equilateral triangles or regular hexagons, and particularly preferably equilateral triangles. In this sense, the protrusions 18 are aligned along the central axes C of the lift pin holes 16. H 2, or six-fold rotational symmetry as in electrostatic chuck heater 10' shown in FIG. 4. The size of the constituent unit of the regular pattern is not particularly limited, but the circumscribing circle diameter of the constituent unit is preferably 4 to 30 mm, more preferably 5 to 26 mm, still more preferably 7 to 26 mm, and particularly preferably 7 to 15 mm. When the constituent unit of the regular pattern is an equilateral triangle, one side of the equilateral triangle is preferably 4 to 30 mm, more preferably 5 to 26 mm, still more preferably 7 to 26 mm, and particularly preferably 7 to 15 mm.

[0022] The ceramic shaft 14 is a hollow shaft attached to the second surface 12b of the ceramic plate 12, and may have the same configuration as a ceramic shaft employed in a known electrostatic chuck heater or ceramic heater. The ceramic shaft 14 has an internal space for accommodating the ESC rod 24 and the heater rod 26. The ceramic shaft 14 is preferably made of the same ceramic material as the ceramic plate 12. Therefore, the ceramic shaft 14 is preferably made of aluminum nitride. The upper end surface of the ceramic shaft 14 is preferably joined to the second surface 12b of the ceramic plate 12 by solid-state bonding or diffusion bonding. The outer diameter of the ceramic shaft 14 is not particularly limited and is, for example, about 40 mm. The inner diameter of the ceramic shaft 14 (diameter of the internal space) is also not particularly limited and is, for example, about 36 mm.

[0023] The electrostatic chuck heater 10 may further include an ESC rod 24 and a heater rod 26 in the internal space of the ceramic shaft 14. One end of the ESC rod 24 is connected to the ESC electrode 20, and the other end is connected to an external power supply (not shown). Similarly, one end of the heater rod 26 is connected to the heater electrode 22, and the other end is connected to a heater power supply (not shown). With this configuration, a power supply path to the ESC electrode 20 and the heater electrode 22 is secured.

[0024] As described above, the electrostatic chuck heater according to the present invention is used in a film formation apparatus, particularly a film formation apparatus for a semiconductor manufacturing process. Therefore, according to another aspect of the present invention, a film formation apparatus is provided that includes a film formation chamber (not shown) and an electrostatic chuck heater 10 provided in the film formation chamber. As described above, examples of such a film formation apparatus include a CVD (chemical vapor deposition) apparatus (e.g., a thermal CVD apparatus, a plasma CVD apparatus, a photo CVD apparatus, and an MOCVD apparatus) and a PVD (physical vapor deposition) apparatus.

[0025] The electrostatic chuck heater 10 is used in the film forming apparatus as follows. The electrostatic chuck heater 10 is disposed in the chamber of the film forming apparatus, and the wafer W is placed on the protrusions 18 of the ceramic plate 12. Then, a voltage is applied to the ESC electrode 20, and the wafer W is chucked by the Johnson-Rahbek force. The temperature of the ceramic plate 12 is obtained based on a detection signal of a thermocouple (not shown), and the voltage and current applied to the heater electrode 22 are controlled so that the temperature becomes a target temperature. In this state, a film may be formed on the upper surface of the wafer W by CVD or the like. After the film is formed, lift pins (not shown) come out from the first surface 12a of the ceramic plate 12 through the lift pin holes 16, lift the wafer W upward, and assist in removing the wafer W from the electrostatic chuck heater 10.

Claims

1. An electrostatic chuck heater for use in a film forming apparatus, comprising: a ceramic plate having a first surface on which a wafer to be deposited is placed and a second surface opposite to the first surface, and incorporating an ESC electrode and a heater electrode; a ceramic shaft attached to the second surface of the ceramic plate and having an interior space for accommodating an ESC rod connected to the ESC electrode and a heater rod connected to the heater electrode; a plurality of lift pin holes extending from the first surface to the second surface of the ceramic plate; a plurality of protrusions disposed on a first surface of the ceramic plate at equal intervals and rotationally symmetrical with respect to a central axis of each of the lift pin holes; An electrostatic chuck heater comprising:

2. 2. The electrostatic chuck heater of claim 1, wherein the plurality of protrusions are arranged asymmetrically with respect to a central axis of the ceramic plate.

3. 3. The electrostatic chuck heater according to claim 1, wherein the plurality of protrusions are arranged according to a regular pattern having a unit shape selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon.

4. 4. The electrostatic chuck heater according to claim 3, wherein the constituent unit of the regular pattern has a circumscribed circle diameter of 4 to 30 mm.

5. 4. The electrostatic chuck heater according to claim 3, wherein the constituent units of the regular pattern are equilateral triangles.

6. 6. The electrostatic chuck heater according to claim 5, wherein one side of the equilateral triangle is 4 to 30 mm.

7. 6. The electrostatic chuck heater according to claim 5, wherein the plurality of protrusions are arranged to have three-fold or six-fold rotational symmetry with respect to a central axis of each of the lift pin holes.

8. 3. The electrostatic chuck heater according to claim 1, wherein the distance between the central axes of the adjacent protrusions is 4 to 30 mm.

9. 3. The electrostatic chuck heater according to claim 1, wherein the projections have a height of 0.001 to 0.1 mm.

10. 3. The electrostatic chuck heater according to claim 1, wherein the lift pin hole has a circular shape in a plan view.

11. 3. The electrostatic chuck heater according to claim 1, wherein the number of the lift pin holes is three or four.

12. 3. The electrostatic chuck heater according to claim 1, wherein the lift pin holes have a diameter of 1 to 5 mm.

13. 3. The electrostatic chuck heater according to claim 1, further comprising: the ESC rod and the heater rod in the internal space of the ceramic shaft.

14. A film formation apparatus comprising: a film formation chamber; and the electrostatic chuck heater according to claim 1 or 2, which is provided in the film formation chamber.

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