Ceramic susceptor

Abstract

Provided is a ceramic susceptor that makes it possible to form a film with excellent uniformity of film thickness by suppressing decreases in plasma density around lift pin holes. This ceramic susceptor comprises: a ceramic plate that has a first surface including a plurality of protrusions, and a second surface; a first RF electrode, made of a metal mesh, that is embedded within the ceramic plate at a position of a depth of a distance L1 from peak surfaces of the protrusions; a second RF electrode, made of a metal mesh, that is embedded within the ceramic plate at a position of a depth of a distance L2 (where L2 > L1) from the peak surfaces of the protrusions; and a plurality of lift pin holes, each having a cross sectional area SL, that penetrate from the first surface to the second surface of the ceramic plate. The first RF electrode has opening holes each having an area S1 at a plurality of positions corresponding to the lift pin holes. The second RF electrode has opening holes each having an area S2 at a plurality of positions corresponding to the lift pin holes. A cross-sectional area S L, the area S1, and the area S2 satisfy the relationships 3.0 ≤ S1 / SL ≤ 10.5 and 2.0 ≤ S2 / SL ≤ 4.5.

Description

Ceramic Susceptor

[0001] The present disclosure relates to ceramic susceptors.

[0002] In semiconductor manufacturing processes, susceptors are used to support wafers in film deposition and etching equipment. A widely used susceptor includes a ceramic plate on which the wafer is placed and a cylindrical ceramic shaft attached to the ceramic plate. The ceramic plate typically has a ceramic base made of aluminum nitride (AlN) or other material with excellent heat and corrosion resistance, with internal electrodes embedded therein, such as heater electrodes, RF electrodes, and electrostatic chuck (ESC) electrodes.

[0003] A ceramic susceptor is known that has lift pin holes in a plate portion of the susceptor on which a 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 deposition, and a plurality of lift pin holes (e.g., three or four holes) are generally provided at positions spaced apart from one another.

[0004] Patent Document 1 (JP 2005-340442 A) discloses an electrostatic chuck including an attracting electrode provided on one main surface of a plate-like body and an insulating layer provided on the attracting electrode. The upper surface of the insulating layer forms a mounting surface on which a wafer is placed. The attracting electrode is bent at its periphery toward the opposite side to the wafer mounting surface, and a chamfered portion is formed in the insulating layer covering the periphery of the attracting electrode. The electrostatic chuck disclosed in this document includes lift pin holes, and the periphery of the attracting electrode is disclosed as including the lift pin holes.

[0005] Japanese Patent Application Laid-Open No. 2005-340442

[0006] As described above, the lift pins function to lift a wafer placed on a ceramic susceptor. Therefore, the plate portion (ceramic plate) of the ceramic susceptor requires through-holes, i.e., lift pin holes, through which the lift pins can be inserted. Therefore, the RF electrode (e.g., a mesh electrode) embedded in the ceramic plate also needs to have openings at positions corresponding to the lift pin holes. However, because the RF electrode is an electrode for generating plasma, the plasma density decreases around the lift pin holes, which tends to result in singularities in the film deposition distribution. The presence of such singularities can result in significant variations in the film thickness of films deposited using the ceramic susceptor, potentially reducing the yield of semiconductor chips.

[0007] The present inventors have now discovered a method for embedding a first RF electrode and a second RF electrode at different depths in a ceramic plate, and a lift pin hole having a cross-sectional area S Ｌ , the area S of the opening hole at the position corresponding to the lift pin hole of the first RF electrode １ , and the area S of the opening hole at the position corresponding to the lift pin hole of the second RF electrode ２ It has been found that by making the above relationship satisfy a predetermined relationship, it is possible to suppress the decrease in plasma density around the lift pin hole and realize film formation with excellent film thickness uniformity.

[0008] Therefore, an object of the present invention is to provide a ceramic susceptor that has lift pin holes but that can suppress a decrease in plasma density around the lift pin holes, thereby enabling film deposition with excellent film thickness uniformity.

[0009] According to the present disclosure, the following aspects are provided: [Aspect 1] A circular ceramic plate having a first surface on which a plurality of protrusions having a certain height are provided and a second surface opposite to the first surface, and a distance L from the top surface of the protrusions in the ceramic plate. １ The diameter d is buried at a depth of １ a first RF electrode formed of a metal mesh having a circular shape, and a distance L from the top surface of the protrusion in the ceramic plate; ２ (However, L ２ >L １The diameter d ２ a second RF electrode formed of a metal mesh having a circular shape of 1000 mm; and a plurality of metal meshes having a cross-sectional area S Ｌ and a lift pin hole having an area S １ and the second RF electrode has an area S at a plurality of positions corresponding to the lift pin holes. ２ The cross-sectional area S Ｌ , the area S １ and the area S ２ However, the following relationship exists: 3.0≦S １ / S Ｌ ≦10.5, and 2.0≦S ２ / S Ｌ The ceramic susceptor satisfies the following condition: １ and the distance L ２ When expressed in mm, the following relationship is satisfied: 0.9≦L １ ≦1.5, and 2.0≦L ２ The ceramic susceptor according to aspect 1, wherein the diameter d １ and the diameter d ２ When expressed in mm, the following relationship is satisfied: 290≦d １ ≦300, and 310≦d ２The ceramic susceptor according to Aspect 1 or 2, satisfying the following condition:≦350. [Aspect 4] The ceramic susceptor according to any one of Aspects 1 to 3, wherein the diameter of the ceramic plate is 330 to 380 mm. [Aspect 5] The ceramic susceptor according to any one of Aspects 1 to 4, wherein the ceramic plate comprises aluminum nitride and / or aluminum oxide. [Aspect 6] The ceramic susceptor according to any one of Aspects 1 to 5, further comprising: a cylindrical ceramic shaft attached to the second surface of the ceramic plate and having an internal space. [Aspect 7] The ceramic susceptor according to Aspect 6, further comprising: an RF rod connected to each of the first RF electrode and the second RF electrode and extending through the internal space. [Aspect 8] The ceramic susceptor according to any one of Aspects 1 to 7, wherein the lift pin holes have a circular shape in plan view. [Aspect 9] The ceramic susceptor according to any one of Aspects 1 to 8, wherein the number of lift pin holes is three or four. [Aspect 10] The ceramic susceptor according to any one of Aspects 1 to 9, wherein the lift pin holes have a diameter of 1 to 5 mm. [Aspect 11] The ceramic susceptor according to any one of Aspects 1 to 10, wherein the first RF electrode and / or the second RF electrode also function as an ESC electrode. [Aspect 12] The ceramic susceptor according to any one of Aspects 1 to 11, further comprising a heater electrode embedded in the ceramic plate at a depth closer to the second surface than the first RF electrode and the second RF electrode. [Aspect 13] The ceramic susceptor according to Aspect 12, further comprising: a cylindrical ceramic shaft attached to the second surface of the ceramic plate and having an internal space; and a heater rod connected to the heater electrode and extending through the internal space.

[0010] It is a schematic cross-sectional view showing an example of a ceramic susceptor according to the present invention. It is a schematic top view showing an example of the ceramic susceptor shown in Figure 1. It is a schematic top view showing a first RF electrode shown in Figure 1. It is a schematic top view showing a second RF electrode shown in Figure 1.

[0011] The ceramic susceptor according to the present invention is a ceramic platform for supporting a wafer in a semiconductor manufacturing apparatus. Preferably, the ceramic susceptor according to the present invention is a ceramic heater for a semiconductor film formation apparatus. Typical examples of film formation apparatuses 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, with plasma CVD apparatuses being particularly preferred.

[0012] 1 and 2 show an example of a ceramic susceptor. The ceramic susceptor 10 shown in FIGS. 1 and 2 includes a ceramic plate 12, a first RF electrode 14, a second RF electrode 16, lift pin holes 18, and, if desired, a ceramic shaft 20. The ceramic plate 12 is disk-shaped and has a first surface 12a with a plurality of protrusions 12p of a certain height, and a second surface 12b opposite the first surface 12a. The first surface 12a is a surface on which a wafer W is placed, and more specifically, the wafer W can be placed on the top surfaces of the protrusions 12p that partially constitute the first surface 12a. The first RF electrode 14 has a diameter d １ The metal mesh has a circular shape, and is spaced a distance L from the top surface of the protrusion 12p in the ceramic plate 12. １ The second RF electrode 16 is buried at a depth of d ２ The metal mesh has a circular shape, and is spaced a distance L from the top surface of the protrusion 12p in the ceramic plate 12. ２ (However, L ２ >L １ The lift pin holes 18 are a plurality of holes that penetrate the ceramic plate 12 from the first surface 12a to the second surface 12b, and each of the lift pin holes 18 has a cross-sectional area of ​​S Ｌ As shown in FIG. 3, the first RF electrode 14 has openings 14a at a plurality of positions corresponding to the lift pin holes 18, and the area of ​​each of the openings 14a is S １ As shown in FIG. 4, the second RF electrode 16 has openings 16a at a plurality of positions corresponding to the lift pin holes 18, and the area of ​​each opening 16a is S ２ And the cross-sectional area S Ｌ, area S １ and area S ２ However, 3.0≦S １ / S Ｌ ≦10.5 and 2.0≦S ２ / S Ｌ In this way, the first RF electrode 14 and the second RF electrode 16 are embedded at different depths in the ceramic plate 12, and the cross-sectional area S Ｌ , the area S of the opening hole at the position corresponding to the lift pin hole 18 of the first RF electrode 14 １ , and the area S of the opening hole at the position corresponding to the lift pin hole of the second RF electrode ２ By making the above relationship satisfy a predetermined relationship, it is possible to suppress a decrease in plasma density around the lift pin holes 18 and realize film formation with excellent film thickness uniformity.

[0013] That is, as mentioned above, when providing lift pin holes in a ceramic plate, it is necessary to provide opening holes in the RF electrode embedded in the ceramic plate at positions corresponding to the lift pin holes. However, since the RF electrode is an electrode for generating plasma, the plasma density decreases around the lift pin holes, which is likely to result in singular points in the film formation distribution. If such singular points exist, the film formed using the ceramic susceptor will have large variations in thickness, which may result in a decrease in the yield of semiconductor chips. This problem is successfully solved by the present invention. That is, two types of RF electrodes, the first RF electrode 14 and the second RF electrode 16, are embedded at different depths, and the areas of the opening holes 14a and 16a of the first RF electrode 14 and the second RF electrode 16, respectively (i.e., S １ and S ２ ) is the cross-sectional area S of the lift pin hole 18 ＬThe above-mentioned relationship is satisfied while taking into account the balance between the above and the above. In this way, it is possible to suppress the decrease in plasma density around the opening 14a of the first RF electrode 14 (which would have occurred if the second RF electrode 16 had not been present). In other words, while the desired plasma is generated by the first RF electrode 14, the decrease in plasma density caused by the opening 14a can be compensated for by the plasma generated by the second RF electrode 16. Although the second RF electrode 16 also has the opening 16a, the plasma density is increased by 3.0≦S １ / S Ｌ ≦10.5 and 2.0≦S ２ / S Ｌ By satisfying the relationship of ≦4.5, it is considered that the complementary effect of the second RF electrode 16 in increasing the plasma density is more dominant than the decrease in plasma density due to the opening holes 16a of the second RF electrode 16. In other words, it can be said that the presence of the second RF electrode 16 reduces the influence of the lift pin holes 18 or the opening holes 14a of the first RF electrode 14 as singular points. As a result, it is possible to suppress the decrease in plasma density around the lift pin holes 18 and achieve film formation with excellent film thickness uniformity.

[0014] From this viewpoint, the cross-sectional area S Ｌ and area S １ is 3.0≦S １ / S Ｌ ≦10.5, preferably 4.0≦S １ / S Ｌ ≦10.0, more preferably 4.0≦S １ / S Ｌ ≦8.0, particularly preferably 4.0≦S １ / S Ｌ ≦6.0. Ｌ and area S ２ is 2.0≦S ２ / S Ｌ ≦4.5, preferably 2.5≦S ２ / S Ｌ ≦4.5, more preferably 3.0≦S ２ / S Ｌ≦4.0. The diameter of the lift pin hole 18 may not be constant in the depth direction. For example, as shown in FIG. 1, the lift pin hole 18 may have an expanded diameter in the vicinity of the first surface 12a. In such a case, the cross-sectional area S Ｌ is specified as the cross-sectional area of ​​the hole observed as a through-hole when the ceramic plate 12 is viewed from above. Therefore, in the embodiment shown in FIG. 1, the cross-sectional area of ​​the lift pin hole 18 when viewed from the second surface 12b is defined as the cross-sectional area S of the lift pin hole 18. Ｌ It should be adopted as such.

[0015] The ceramic plate 12 is not particularly limited as long as it is a disk-shaped plate having a plurality of protrusions 12p of a certain height on the first surface 12a, and may have a configuration similar to that of ceramic plates used in known ceramic susceptors. The ceramic plate 12 preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride, in its main portion (i.e., the ceramic base) other than the embedded members such as the first RF electrode 14, the second RF electrode 16, and the heater electrode 24, from the viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon.

[0016] The ceramic plate 12 is disk-shaped. However, the planar shape of the disk-shaped ceramic plate 12 does not need to be a perfect circle; for example, it may be an incomplete circle with a portion missing, such as an orientation flat. The size of the ceramic plate 12 may be determined appropriately depending on the diameter of the wafer to be used, but is not particularly limited, and is typically 330 to 380 mm. The thickness of the ceramic plate 12 is typically 10 to 25 mm.

[0017] The first surface 12a of the ceramic plate 12 has a plurality of protrusions 12p of a uniform height. The protrusions 12p contact the back surface of the wafer W to support the wafer W, and are preferably formed at equal intervals on the first surface 12a of the ceramic plate 12. The shape of each protrusion 12p is not particularly limited, but is preferably cylindrical. The diameter of each protrusion 12p 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 protrusions 12p are preferably integrally formed with the ceramic plate 12 by embossing or the like. Therefore, like the ceramic plate 12, the protrusions 12p also preferably contain aluminum nitride or aluminum oxide, and more preferably aluminum nitride. The height of the protrusions 12p 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 protrusions 12p 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.

[0018] The plurality of protrusions 12p are preferably arranged according to (or to form) a regular pattern having a constituent unit selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon. That is, the centers of the plurality of protrusions 12p are preferably arranged so as to be located on an imaginary line (e.g., a vertex in the case of a polygon) that forms a regular pattern in which the plurality of constituent units are repeated. In other words, it is preferable that an imaginary figure drawn by connecting the centers of adjacent protrusions 12p forms a regular pattern having a constituent unit selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon.

[0019] The first RF electrode 14 and the second RF electrode 16 are electrodes that enable film formation by a plasma CVD process when high frequency waves are applied to them. Similar to known RF electrodes, the first RF electrode 14 and the second RF electrode 16 are each made of a metal mesh. The metal mesh may be, for example, a sheet-like mesh made by weaving thin metal wires into a net shape.

[0020] The first RF electrode 14 and the second RF electrode 16 are each spaced apart from the top surface of the protrusion 12p in the ceramic plate 12 by a distance L １ and L ２ Depth position (where L ２ >L １ That is, the first RF electrode 14 is buried at a depth relatively close to the first surface 12a, while the second RF electrode 16 is buried at a depth farther from the first surface 12a than the first RF electrode 14. １ When expressed in mm, preferably 0.9≦L １ ≦1.5, more preferably 1.0≦L １ ≦1.5, more preferably 1.0≦L １ ≦1.3 while the distance L ２ is preferably 2.0≦L when expressed in mm. ２ ≦3.0, more preferably 2.5≦L ２ By setting the distance L within these ranges, it is possible to generate plasma in a well-balanced manner by the first RF electrode 14 and the second RF electrode 16. １ If the distance L is not too small, it is possible to prevent the influence of the first RF electrode 14 on the plasma from becoming too large. ２ Since the distance between the first electrode 11 and the second electrode 16 is not too large, the ceramic portion that can function as a dielectric layer and is located on the upper surface of the second RF electrode 16 does not become too thick, and therefore the effect of the second RF electrode 16 on the plasma (particularly the effect of complementing the plasma density) can be reliably obtained.

[0021] The first RF electrode 14 and the second RF electrode 16 each have a diameter d １ and d ２The first RF electrode 14 and the second RF electrode 16 have a circular shape of . The circular shapes of the first RF electrode 14 and the second RF electrode 16, like the ceramic plate 12, do not need to be perfect circles, and may be incomplete circles with a portion missing, such as an orientation flat. The first RF electrode 14 and the second RF electrode 16 preferably have a diameter slightly smaller than that of the ceramic plate 12, but may have different sizes. In this regard, the diameter d ２ is the diameter d of the first RF electrode 14 １ It is preferable that the diameter is larger than d １ and diameter d ２ When expressed in mm, 290≦d １ ≦300 and 310≦d ２ Preferably, 295≦d １ ≦300 and 315≦d ２ ≦330.

[0022] The first RF electrode 14 has opening holes 14a at a plurality of positions corresponding to the lift pin holes 18, as shown in Fig. 3. The second RF electrode 16 has opening holes 16a at a plurality of positions corresponding to the lift pin holes 18, as shown in Fig. 4. The second RF electrode 16 may also have other opening holes 16b for passing RF rods 22 to be connected to the first RF electrode 14.

[0023] An RF rod 22 is connected to each of the first RF electrode 14 and the second RF electrode 16 for power supply, and the RF rod 22 extends through the internal space S of the ceramic shaft 20 and is connected to an external power source (not shown) or is grounded. Therefore, the ceramic susceptor 10 may further include an RF rod 22 connected to each of the first RF electrode 14 and the second RF electrode 16 and extending through the internal space S.

[0024] The first RF electrode 14 and / or the second RF electrode 16 may also function as an ESC electrode. ESC electrode is an abbreviation for electrostatic chuck (ESC) electrode, and is also called an electrostatic electrode. When the first RF electrode 14 and / or the second RF electrode 16 functions as an ESC electrode, the first RF electrode 14 and / or the second RF electrode 16 chucks the wafer W placed on the surface of the ceramic plate 12 by the Johnsen-Rahbek force when a voltage is applied thereto by an external power supply.

[0025] The lift pin holes 18 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 18 are holes used to insert lift pins (not shown) for lifting the wafer W from below after film formation. That is, after film formation, the lift pins come out of the first surface 12a of the ceramic plate 12 through the lift pin holes 18 and lift the wafer W upward, making it easy to remove the wafer W from the ceramic susceptor 10.

[0026] The planar shape of the lift pin holes 18 may be any shape, such as circular or polygonal, but is preferably circular. The number of lift pin holes 18 provided in the ceramic plate 12 is preferably three or four, and more preferably three. With such a small number of holes, a large effective area of ​​the ceramic plate 12 can be secured while sufficient fulcrums for lifting the wafer W by the lift pins (not shown) can be secured. The diameter of the lift pin holes 18 is not particularly limited, but is preferably 1 to 5 mm, more preferably 2 to 4 mm, and even more preferably 2 to 3 mm.

[0027] The heater electrode 24 may be embedded in the ceramic plate 12 at a depth closer to the second surface 12b than the first RF electrode 14 and the second RF electrode 16. The heater electrode 24 is not particularly limited, and 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 24 for power supply, and the heater rods 26 extend through the internal space S and are connected to a heater power supply (not shown). When power is supplied from the heater power supply, the heater electrode 24 generates heat and heats the wafer W placed on the surface of the ceramic plate 12. The heater electrode 24 is not limited to a coil, and may be, for example, a ribbon (a thin, elongated plate), a mesh, or a print. Therefore, the ceramic susceptor 10 may further include a heater rod 26 connected to the heater electrode 24 and extending through the internal space S.

[0028] A ceramic shaft 20 may be attached (preferably concentrically) to the second surface 12b of the ceramic plate 12. The ceramic shaft 20 is a cylindrical member with an internal space S and may have a configuration similar to that of ceramic shafts used in known ceramic susceptors or ceramic heaters. The internal space S is configured so that terminal rods such as the RF rod 22 and the heater rod 26 pass through it. The ceramic shaft 20 is preferably made of the same ceramic material as the ceramic plate 12. Therefore, the ceramic shaft 20 preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride. The upper end surface of the ceramic shaft 20 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 20 is not particularly limited, but is preferably 40 to 60 mm. The inner diameter of the ceramic shaft 28 (the diameter of the internal space S) is also not particularly limited, but is preferably 33 to 55 mm.

[0029] An example of how the ceramic susceptor 10 is used in a film formation apparatus is as follows. The ceramic susceptor 10 is placed in the chamber of the film formation apparatus, and a wafer W is placed on the protrusions 12p of the ceramic plate 12. Then, RF current is passed through the first RF electrode 14 and the second RF electrode 16 to generate plasma between the first RF electrode 14 and the second RF electrode 16, which also serve as ESC electrodes. At this time, the wafer W may be chucked by the Johnson-Rahbek force by applying a voltage to the first RF electrode 14 and the second RF electrode 16, which also serve as ESC electrodes. Alternatively, the temperature of the ceramic plate 12 is determined based on a detection signal from a thermocouple (not shown), and the voltage and current applied to the heater electrode 24 are controlled so that the temperature reaches 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 film formation, lift pins (not shown) extend from the first surface 12a of the ceramic plate 12 through the lift pin holes 18 to lift the wafer W upward and assist in removing the wafer W from the ceramic susceptor 10.

[0030] The present invention will be explained in more detail by the following examples, but the present invention is not limited to the following examples.

[0031] Examples 1 to 7 (1) Fabrication of Ceramic Susceptor A ceramic susceptor 10 (ceramic heater) having the structure shown in Figures 1 and 2 was fabricated by a known procedure using the following components. <Components and Their Specifications> Ceramic plate 12: Disc-shaped aluminum nitride sintered body (diameter: 330 mm, thickness: 19 mm) (first RF electrode 14, second RF electrode 16, and heater electrode 24 embedded inside) Ceramic shaft 28: Cylindrical aluminum nitride sintered body (height: 166 mm, outer diameter: 40 mm, inner diameter: 36 mm) First RF electrode 14: Distance L shown in Table 1 from the top surface of protrusion 12p in ceramic plate 12 １ 3, a circular metal mesh (made of molybdenum, diameter: 299 mm) embedded at a depth of 1000 m / s.; Opening holes 14a of the first RF electrode 14: three circular holes formed at rotationally symmetric positions as shown in FIG. 3 (each opening hole 14a is a hole having a diameter of 1000 m / s.) １ / S ＬSecond RF electrode 16: distance L shown in Table 1 from the top surface of protrusion 12p in ceramic plate 12 ２ 4, a circular metal mesh (made of molybdenum, diameter: 315 mm) embedded at a depth of 1000 m / s.; Opening holes 16a of the second RF electrode 16: three circular holes formed at rotationally symmetric positions as shown in FIG. 4 (each opening hole 16a is a circular hole having a diameter of 1000 m / s.) ２ / S Ｌ Aperture 16b of second RF electrode 16: one circular hole formed at the center as shown in FIG. 4 Lift pin holes 18: three holes at rotationally symmetric positions as shown in FIG. 2 (shape: circular, diameter: 3.5 mm, cross-sectional area S of lift pin hole 18 when viewed from above) Ｌ : 9.62 mm ２ ) RF rod 22: Two terminal rods made of nickel Heater electrode 24: A two-zone heater including an inner zone heater circuit and an outer zone heater circuit, each heater circuit being composed of a three-dimensional coil-shaped resistance heating element (material: molybdenum) arranged in a single stroke Heater rod 26: Four terminal rods made of nickel (two terminal rods are connected to each of the inner zone heater circuit and the outer zone heater circuit)

[0032] The ceramic plate 12 having the first RF electrode 14, the second RF electrode 16, and the heater electrode 24 embedded therein was fabricated by the following procedure. First, aluminum nitride powder was press-molded to obtain a first aluminum nitride compact. Aluminum nitride powder and the heater electrode 24 were arranged on the obtained first aluminum nitride compact according to a predetermined circuit pattern, and the resulting compact was press-molded to obtain a second aluminum nitride compact having the heater electrode 24 embedded therein. Aluminum nitride powder and the second RF electrode 16 were arranged on the obtained second aluminum nitride compact, and the resulting compact was press-molded to obtain a third aluminum nitride compact having the second RF electrode 16 further embedded therein. Aluminum nitride powder and the first RF electrode 14 were arranged on the obtained third aluminum nitride compact, and the resulting compact was press-molded to obtain a fourth aluminum nitride compact having the first RF electrode 14 further embedded therein. In this manner, a press-molded body was obtained, consisting of an aluminum nitride compact having the first RF electrode 14, the second RF electrode 16, and the heater electrode 24 embedded therein, as shown in FIG. 1 . The obtained press-molded body (laminate) was fired under known conditions in a nitrogen atmosphere to obtain the ceramic plate 12 having the first RF electrode 14, the second RF electrode 16, and the heater electrode 24 embedded therein.

[0033] (2) Evaluation The obtained ceramic susceptors (ceramic heaters) were evaluated as follows.

[0034] <Film Formation Evaluation> A ceramic susceptor 10 was installed in the chamber of a plasma CVD apparatus. In the plasma CVD apparatus equipped with the ceramic susceptor 10, plasma was generated under the conditions of a film formation temperature of 600°C, a furnace pressure of 3 Torr, and an RF power of 500 W. Tetraethyl orthosilicate (TEOS) was used as a precursor, Ar (flow rate: 100 sccm) was used as a carrier gas, and O was used as a reactive gas. ２ (flow rate: 100 sccm) was introduced into the chamber to form a 300 mm thick SiO ２ The film was deposited on a Si wafer.

[0035] The obtained SiO ２ The maximum film thickness Tｍａｘ and the minimum value T ｍｉｎ Measure the film thickness variation T ｄ (%) is calculated using the following formula: ｄ = [(T ｍａｘ -T ｍｉｎ ) / (T ｍａｘ ) × 100. The film thickness uniformity was evaluated and ranked by applying the obtained film thickness variation to the following evaluation criteria: Evaluation A: Film thickness variation is less than 5% Evaluation B: Film thickness variation is 5% or more and 8% or less Evaluation C: Film thickness variation is more than 8%. The obtained evaluation results are shown in Table 1.

[0036]

Claims

1. A disc-shaped ceramic plate having a first surface with a plurality of protrusions of a certain height and a second surface facing the first surface, and a distance L from the top surface of the protrusions in the ceramic plate １ at a depth position of, a metal mesh having a circular shape with a diameter d １ constituting a first RF electrode, and a distance L from the top surface of the protrusions in the ceramic plate ２ (where L ２ > L １ is) at a depth position of, a metal mesh having a circular shape with a diameter d ２ constituting a second RF electrode, and a plurality of lift pin holes penetrating from the first surface to the second surface of the ceramic plate, each having a cross-sectional area S Ｌ , and the first RF electrode has opening holes with an area S １ at a plurality of positions corresponding to the lift pin holes, and the second RF electrode has opening holes with an area S ２ at a plurality of positions corresponding to the lift pin holes, and the cross-sectional area S Ｌ , the area S １ and the area S ２ satisfy the following relationships: 3.0 ≤ S １ / S Ｌ ≤ 10.5, and 2.0 ≤ S ２ / S Ｌ ≤ 4.5, a ceramic susceptor.

2. The distance L １ and the distance L ２ when expressed in units of mm, satisfy the following relationships: 0.9 ≤ L １ ≤ 1.5, and 2.0 ≤ L ２ ≤ 3.

0. The ceramic susceptor according to claim 1 3. The diameter d １ and the diameter d ２ when expressed in units of mm, satisfy the following relationships: 290 ≤ d １ ≤ 300, and 310 ≤ d ２ ≤ 350. The ceramic susceptor according to claim 1 or 2 4. The ceramic susceptor according to claim 1 or 2, wherein the diameter of the ceramic plate is 330 to 380 mm.

5. The ceramic susceptor according to claim 1 or 2, wherein the ceramic plate contains aluminum nitride and / or aluminum oxide.

6. The ceramic susceptor according to claim 1 or 2, further comprising a cylindrical ceramic shaft attached to the second surface of the ceramic plate and having an internal space.

7. The ceramic susceptor according to claim 6, further comprising an RF rod connected to each of the first RF electrode and the second RF electrode and extending through the internal space.

8. The ceramic susceptor according to claim 1 or 2, wherein the planar shape of the lift pin hole is circular.

9. The ceramic susceptor according to claim 1 or 2, wherein the number of lift pin holes is three or four.

10. The ceramic susceptor according to claim 1 or 2, wherein the lift pin hole has a diameter of 1 to 5 mm.

11. The ceramic susceptor according to claim 1 or 2, wherein the first RF electrode and / or the second RF electrode also functions as an ESC electrode.

12. The ceramic susceptor according to claim 1 or 2, further comprising a heater electrode embedded at a depth position closer to the second surface than the first RF electrode and the second RF electrode in the ceramic plate.

13. The ceramic susceptor according to claim 12, further comprising a cylindrical ceramic shaft attached to the second surface of the ceramic plate and having an internal space, and a heater rod connected to the heater electrode and extending through the internal space.

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