Multi-Zone Heater

Abstract

A multi-zone heater capable of heating a wafer placed on one main surface of a disk-shaped ceramic base is provided in the ceramic base, and includes a plurality of lift pin holes through which lift pins for raising and lowering the wafer are inserted, an inner zone heater embedded in an inner zone of the ceramic base, an outer zone heater embedded in an outer zone outside the inner zone, first and second power supply terminals to which both ends of the inner zone heater are connected, first and second lead wires to which both ends of the outer zone heater are connected, a third power supply terminal to which the first lead wire is connected, and a fourth power supply terminal to which the second lead wire is connected, wherein the arrangement of the plurality of lift pin holes, the inner zone heater, and the outer zone heater is line-symmetrical with a common axis of symmetry, and the first and second lead wires are arranged symmetrically with each other along the axis of symmetry.

Description

Technical Field

[0001] The present invention relates to a multi-zone heater for heating a semiconductor wafer.

Background Art

[0002] As a heater for heating a wafer in a semiconductor manufacturing apparatus, a ceramic heater is widely used. As such a ceramic heater, a so-called multi-zone heater configured to be heated by separate heaters in a plurality of zones is known. As one type of such a multi-zone heater, a heating element (coil) for heating the central portion (inner zone) of a disk-shaped ceramic substrate and a heating element (coil) for heating the outer peripheral portion (outer zone) are embedded in one plane inside the ceramic substrate, and a two-zone heater capable of independently controlling the heat generation from each heating element by being able to independently apply a voltage to each heating element is already known (see, for example, Patent Document 1 and Patent Document 2).

[0003] In the case of a multi-zone heater that heats the inner zone and the outer zone with separate heating elements as disclosed in Patent Document 1, generally, the heating elements in each zone are arranged in a plurality of concentric arc shapes concentric with the disk-shaped ceramic substrate. In addition, a connection terminal for carrying out power supply from the outside is provided at the central portion of the ceramic substrate. The heating element arranged in the inner zone is directly connected to such a connection terminal, while the heating element arranged in the outer zone is connected to the connection terminal via a lead wire connecting its end portion and the connection terminal.

[0004] However, the leader lines must be positioned to cross the inner zone. Therefore, the heating elements for the inner zone are folded back at least around the leader lines in the inner zone. As a result, the radius of curvature of the heating elements at the folded portion is significantly different from that of the arc-shaped portion. Depending on how the heating element pattern is arranged, such folding of the heating elements may also occur in other areas, including the outer zone.

[0005] Furthermore, semiconductor manufacturing equipment equipped with a ceramic heater may be provided with support pins (lift pins) capable of supporting and raising a wafer placed on the upper surface of a ceramic substrate, as disclosed in Patent Document 2. The lift pins are provided so as to be insertable into through holes (lift pin holes) provided at predetermined positions in the ceramic substrate. In the case of a ceramic heater equipped with lift pin holes, it is also necessary to position the heating element to avoid (bypass) these lift pin holes. Thus, the radius of curvature of the heating element at the location avoiding the lift pin holes is significantly different from that of the arc-shaped portion.

[0006] From the perspective of improving productivity in semiconductor manufacturing equipment, it is generally desirable that the heating of the wafer by the ceramic heater be as uniform as possible across the wafer surface (high heat uniformity). In other words, it is desirable that the temperature variation across the wafer surface when the wafer is heated be as small as possible.

[0007] However, in multi-zone heaters, the uniformity of the temperature distribution tends to worsen at the points where the heating element is folded over, as described above.

[0008] Furthermore, in the case of ceramic heaters equipped with lift pin holes, the uniformity of the temperature distribution tends to worsen even in areas that avoid the lift pin holes.

[0009] In other words, in multizone heaters equipped with lift pin holes, the uniformity of the temperature distribution tends to deteriorate at singular points (radius of curvature singularities) where the radius of curvature is significantly different from that of the normal arc-shaped portion.

[0010] This is thought to be due to differences in the deformation patterns of the heating element during the manufacturing process of ceramic heaters. Specifically, ceramic heaters are obtained by embedding a heating element in a molded body of ceramic material such as aluminum nitride, silicon carbide, silicon nitride, or aluminum oxide, and then firing the molded body at a temperature exceeding 1500°C while applying a load of several tons. However, the deformation behavior of the heating element during firing differs between the radius of curvature singularity and the normal portion, which is thought to cause variations in heating at the radius of curvature singularity in the finished ceramic heater.

[0011] In some cases, uniform heating can be ensured by using multiple types of heating elements with different thicknesses, materials, etc., resulting in varying heat densities. However, this method is not necessarily suitable for application to radius of curvature singularities.

[0012] Alternatively, one could consider increasing heat uniformity by creating numerous singularities in the radius of curvature, but this is not practical considering the complexity and cost of the design.

[0013] The inventors of the present invention conducted thorough research on ensuring uniform heat distribution in a multi-zone heater equipped with lift pin holes. As a result, they arrived at a configuration that can suitably ensure uniform heat distribution even while having a singularity in the radius of curvature, by comprehensively considering the arrangement of the lift pin holes and the arrangement of the lead wires connecting the heating element located in the outer zone to the power supply connection terminals. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] International Publication No. 2019 / 181500 [Patent Document 2] International Publication No. 2006 / 004045 [Overview of the Initiative]

[0015] This invention has been made in view of the above problems, and aims to improve the uniformity of heat in a multi-zone heater equipped with lift pin holes.

[0016] To solve the above problems, a first aspect of the present invention provides a multizone heater comprising a disc-shaped ceramic substrate having one main surface as a wafer mounting surface, and capable of heating a wafer placed on the one main surface, comprising: a plurality of lift pin holes provided in the ceramic substrate through which lift pins for raising and lowering the wafer can be inserted; an inner zone heater embedded in the inner zone of the ceramic substrate; an outer zone heater embedded in the outer zone of the ceramic substrate outside the inner zone; and a heating element provided in the central part of the ceramic substrate, which is the inner zone The heater comprises a first power supply terminal and a second power supply terminal to which both ends of the inner zone heater are connected, a first lead wire and a second lead wire to which both ends of the outer zone heater are connected, a third power supply terminal and a fourth power supply terminal to which the first lead wire and the second lead wire are connected, provided in the center of the ceramic substrate, wherein the arrangement of the plurality of lift pin holes, the inner zone heater and the outer zone heater is a line-symmetric arrangement with a common axis of symmetry, and the first lead wire and the second lead wire are provided symmetrically to each other along the axis of symmetry.

[0017] A second aspect of the present invention is a multizone heater according to the first aspect, characterized in that the plurality of lift pin holes are arranged on a circle concentric with the ceramic substrate.

[0018] A third aspect of the present invention is a multizone heater according to the second aspect, characterized in that the diameter of the circle concentric with the ceramic substrate is 46% to 88% of the diameter of the ceramic substrate.

[0019] A fourth aspect of the present invention is the multi-zone heater according to any one of the first to third aspects, wherein the inner zone and the outer zone are separated by a virtual boundary circle concentric with the ceramic substrate, and the diameter of the boundary circle is 51% to 82% of the diameter of the ceramic substrate.

[0020] According to the first to fourth aspects of the present invention, it is possible to improve the heat uniformity on the wafer placement surface when heating is performed by the heater, as compared with a multi-zone heater in which the lead wires do not follow the symmetry axis.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic plan view of the multi-zone heater 10. [Figure 2] It is a schematic cross-sectional view of the multi-zone heater 10. [Figure 3] It is a schematic plan view of the asymmetric multi-zone heater 1010. [Figure 4] It is a figure which illustrates the temperature distribution in the wafer mounting surface 22 when heater heating is performed in the multi-zone heater 10. [Figure 5] It is a figure which illustrates the temperature distribution in the wafer mounting surface 22 when heater heating is performed in the asymmetric multi-zone heater 1010. [Figure 6] It is a schematic plan view of the multi-zone heater 10B. [Figure 7] It is a figure which illustrates the temperature distribution in the wafer mounting surface 22 when heater heating is performed in the multi-zone heater 10B. [Figure 8] It is a schematic plan view of the multi-zone heater 10C.

Mode for Carrying Out the Invention

[0022] <Configuration of Multi-Zone Heater> FIG. 1 is a schematic plan view of a multi-zone heater 10 according to an embodiment of the present invention. FIG. 2 is a schematic cross sectionThis is a diagram. In Figure 1, the x, y, and z coordinates are shown in a right-handed system where the left-right direction in the view of the drawing is the x-axis, and the z-axis direction in Figure 2 is the same as in Figure 1.

[0023] The multizone heater 10 is used as a susceptor to support a semiconductor wafer from below in the semiconductor wafer heating process, which is one step in the semiconductor manufacturing process. More specifically, examples of such heating processes include heating a wafer in the process of forming a semiconductor thin film on the wafer by plasma CVD. In this embodiment, the multizone heater 10 is assumed to be used by being incorporated inside a semiconductor manufacturing apparatus (not shown), such as a known plasma CVD apparatus.

[0024] The multi-zone heater 10 mainly comprises a ceramic base 20, an inner zone heater 30, an outer zone heater 40, a first lead wire 41, a second lead wire 42, and a shaft 50.

[0025] The ceramic substrate 20 is a disc-shaped plate member made of a fired ceramic material. Examples of ceramic materials include aluminum nitride, silicon carbide, silicon nitride, and aluminum oxide.

[0026] The ceramic substrate 20 has, for example, a diameter of 320 mm to 385 mm and a thickness of 10 mm to 30 mm. One main surface of the ceramic substrate 20 (the top surface in Figure 2) is the wafer mounting surface 22. The wafer mounting surface 22 may have multiple irregularities formed by embossing or multiple grooves formed thereon.

[0027] Furthermore, the ceramic substrate 20 is provided with a plurality of through-holes, which are lift pin holes 60. Support pins (lift pins), which are provided in a semiconductor manufacturing apparatus (not shown) and are capable of supporting and raising / lowering a wafer placed on the upper surface of the ceramic substrate, can be freely inserted through the plurality of lift pin holes 60. The plurality of lift pin holes 60 are provided at equidistant positions from the axial center C of the ceramic substrate 20 (i.e., on a circle concentric with the ceramic substrate 20) at equiangled intervals in the circumferential direction and arranged symmetrically along the line (y-axis symmetrically in Figure 1). Figure 1 illustrates the case in which three lift pin holes 60 (60a to 60c) are provided in a symmetrically arranged manner, but the number of lift pin holes 60 is not limited to this.

[0028] Furthermore, the other main surface of the ceramic substrate 20 (the bottom surface in Figure 2) serves as the connection surface 24 for the shaft 50. The shaft 50 is a hollow cylindrical member made of a fired ceramic material similar to that of the ceramic substrate 20.

[0029] Furthermore, the ceramic substrate 20 is divided into an inner zone 20a and an outer zone 20b by a virtual boundary circle 26, which is conceived as a circle concentric with the ceramic substrate 20. The inner zone 20a is a circular region inside the virtual boundary circle 26. The outer zone 20b is an annular region outside the virtual boundary circle 26. The virtual boundary circle 26 is located slightly inside the position where the lift pin holes 60 are installed in the radial direction.

[0030] An inner zone heater 30 is embedded in the inner zone 20a, and an outer zone heater 40 is embedded in the outer zone 20b.

[0031] The inner zone heater 30 is a coil that is wired throughout the entire inner zone 20a in a plane (xy plane) parallel to the wafer mounting surface 22 inside the ceramic substrate 20. As shown in Figure 1, the inner zone heater 30 is wired in a single continuous line, with the coil being folded back in a curved manner at the folded portion 35 (35a~35d) near the yz plane passing through the axis center C.

[0032] The outer zone heater 40 is a coil wired inside the ceramic substrate 20, in the same plane (xy plane) as the inner zone heater 30, and extending across the entire outer zone 20b. As shown in Figure 1, the outer zone heater 40 is wired in a single continuous line, with the coil being folded back curvilinearly at the folded portion 47 (47a, 47b) near the yz plane passing through the axis center C.

[0033] As shown in Figure 1, the inner zone heater 30 and the outer zone heater 40 are arranged in a circular arc shape at equal intervals in the radial direction of the ceramic substrate 20, that is, in a concentric circular arc shape, for most of the area except for the folded portion 35 and the folded portion 47.

[0034] Exceptionally, in the vicinity of the lift pin hole 60, the inner zone heater 30 and the outer zone heater 40 are provided with locally curved portions 36 and 48, respectively, in order to suppress the occurrence of temperature unevenness caused by the presence of the lift pin hole 60.

[0035] For example, in the case shown in Figure 1, the inner zone heater 30 has curved portions 36a, 36b, and 36c that curve radially outward near the lift pin holes 60a, 60b, and 60c, respectively.

[0036] Furthermore, the outer zone heater 40 also has curved portions 48a and 48b that curve radially outward near the lift pin holes 60a and 60b, respectively.

[0037] The materials used for the coils constituting the inner zone heater 30 and the outer zone heater 40 include molybdenum, tungsten, or molybdenum / tungsten compounds.

[0038] Furthermore, the number of turns per unit length of the coils constituting the inner zone heater 30 and the outer zone heater 40 may be appropriately changed depending on the location within the inner zone 20a and the outer zone 20b. For example, when plasma heating a wafer, temperature unevenness may occur on the wafer due to partial differences in plasma heat input to the wafer. To eliminate such temperature unevenness, the number of turns per unit length may be changed depending on the location. The more turns per unit length a coil has, the more heat it generates and the higher its temperature tends to become. Instead of changing the number of turns in the coil, the winding diameter or the distance between coils (the distance between adjacent coils) may be changed.

[0039] Both ends of the inner zone heater 30 are connected to a first power supply terminal 31 and a second power supply terminal 32, respectively, which are located in the central part (near the axis center C) of the ceramic substrate 20. As shown in Figure 2, the first power supply terminal 31 and the second power supply terminal 32 are located in the same plane.

[0040] The outer zone heater 40 has two ends 40a and 40b connected to one end of the first lead wire 41 and one end of the second lead wire 42, respectively. The other end of the first lead wire 41 and the other end of the second lead wire 42 are connected to a third power supply terminal 43 and a fourth power supply terminal 44, respectively, located near the axial center C of the ceramic substrate 20. As shown in Figure 2, the third power supply terminal 43 and the fourth power supply terminal 44 are located in the same plane.

[0041] The first leader line 41 and the second leader line 42 are provided in such a manner that they traverse the inner zone 20a. Figure 2 schematically shows how the first leader line 41 traverses the inner zone 20a in a plane perpendicular to the z-axis. More specifically, as shown in Figure 1, the first leader line 41 and the second leader line 42 are provided between two folded portions 35a and 35b of the inner zone heater 30.

[0042] The first leader wire 41 and the second leader wire 42 are made of wire. The wire material can be molybdenum, tungsten, or a molybdenum / tungsten compound. The wire diameter is not particularly limited, but is preferably 0.3 mm or more and 1.0 mm or less.

[0043] In Figure 1, the first leader line 41 and the second leader line 42 are straight lines that are symmetrical to each other along the y-axis passing through the axis center C. In other words, they are provided along the axis of symmetry of the symmetrical arrangement of the lift pin holes 60. Note that being straight lines is not a necessary configuration; as long as they are symmetrical, the shape when viewed from above may be meandering (i.e., winding) or curved overall. In this embodiment, the symmetrical arrangement of the first leader line 41 and the second leader line 42 includes cases where they are positioned approximately symmetrically, and deviations that inevitably occur during manufacturing are acceptable. For example, deviations of about 4 mm or less from the original symmetrical position are permitted. This degree of positional deviation will not worsen the heat uniformity described later.

[0044] The first power supply terminal 31 and the second power supply terminal 32 are connected to power supply members, which are power supply lines from the inner zone heater power supply 37. 34 and 33 The following are also connected. In addition, the third power supply terminal 43 and the fourth power supply terminal 44 are connected to power supply members 45 and 46, which are power supply lines from the power supply 49 for the outer zone heater, respectively. Various connection methods can be applied to these connections, such as screws, crimping, fitting, brazing, welding, and eutectic soldering. Furthermore, the arrangement of the first power supply terminal 31 and the second power supply terminal 32, and the arrangement of the third power supply terminal 43 and the fourth power supply terminal 44 are symmetrical with respect to the y-axis.

[0045] The power supply members 33, 34, 45, and 46 are disposed inside the shaft 50. The power supply members 33, 34, 45, and 46 are preferably made of metal, and more preferably of nickel. Alternatively, they may be made of a nickel alloy such as Inconel (a registered trademark of Special Metal Corporation). Alternatively, they may be made of a tungsten / nickel composite material. Examples of the shapes of the power supply members 33, 34, 45, and 46 include rod shape and wire shape.

[0046] The operation of the inner zone heater power supply 37 and the outer zone heater power supply 49 is controlled by the controller 52. As a result, in the multi-zone heater 10 according to this embodiment, the temperature control of the inner zone 20a and the outer zone 20b can be performed independently. In other words, the multi-zone heater 10 has a configuration that allows the inner zone 20a and the outer zone 20b outside of it to be heated independently by separate heaters.

[0047] <Details of the arrangement of the components> In the multi-zone heater 10 according to this embodiment, which has the configuration shown in Figure 1, the arrangement of each component is determined from the viewpoint of ensuring uniform heating on the wafer mounting surface 22.

[0048] Specifically, the inner zone heater 30 and the outer zone heater 40 are arranged in a concentric arc shape for most of their length, although they have folded portions 35 and 47.

[0049] The shapes of the folded portions 35 and 47 are determined so as to suppress temperature variations caused by the folding.

[0050] Furthermore, the curved portion 36 of the inner zone heater 30 and the curved portion 48 of the outer zone heater 40, which are provided near the lift pin hole 60, are provided for the purpose of suppressing temperature variations caused by the presence of the lift pin hole 60.

[0051] Furthermore, the folded portions 35 and 47, and the curved portions 36 and 48 have significantly different radii of curvature compared to the concentric arc-shaped portions of the inner zone heater 30 and the outer zone heater 40; therefore, these locations are also referred to as points of radius of curvature singularity.

[0052] In other words, in the multi-zone heater 10, an inner zone heater 30 and an outer zone heater 40 are arranged so as to suppress temperature variations at the radius of curvature singularity.

[0053] Moreover, in this case, the arrangement of the inner zone heater 30, the outer zone heater 40, and the lift pin hole 60 is such that they are arranged symmetrically along a common axis of symmetry. In the case shown in Figure 1, these components are arranged symmetrically along the y-axis, thereby achieving this symmetrical arrangement.

[0054] In addition to these, in the multi-zone heater 10 according to this embodiment, the first leader line 41 and the second leader line 42 are provided along the axis of symmetry of the line-symmetric arrangement. And, in accordance with the arrangement of the first leader line 41 and the second leader line 42, the arrangement of the folded portion 35 of the inner zone heater 30 and the arrangement of the folded portion 47 of the outer zone heater 40 are also line-symmetric.

[0055] In the multizone heater 10 having the above configuration, even though the first leader wire 41 and the second leader wire 42 are both located between a pair of folded portions 35 (35a, 35b) and between a pair of folded portions 47 (47a, 47b), which are singular points of radius of curvature, superior uniform heating is achieved compared to a multizone heater in which the first leader wire 41 and the second leader wire 42 are located at positions different from the axis of symmetry of the symmetrical arrangement of the lift pin holes 60.

[0056] Figure 3 is a schematic plan view of a multizone heater (hereinafter referred to as an asymmetric multizone heater) 1010, shown for comparison, in which the first leader line 41 and the second leader line 42 are located at positions different from the axis of symmetry of the symmetrical arrangement of the lift pin holes 60.

[0057] The asymmetrical multi-zone heater 1010 is the same as the multi-zone heater 10 shown in Figure 1, in that an inner zone heater 30 is embedded in the inner zone 20a and an outer zone heater 40 is embedded in the outer zone 20b, and the arrangement of the lift pin holes 60 is the same. However, most of the first leader line 41 and the second leader line 42 are in the form of straight lines that are symmetrical to each other along the x-axis passing through the axis center C. Accordingly, the folded portions of the inner zone heater 30 and the outer zone heater 40 are also provided along the x-axis. As a result, the first leader line 41 and the second leader line 42 are provided at positions different from the axis of symmetry of the symmetrical arrangement of the lift pin holes 60. However, the arrangement of the first power supply terminal 31 and the second power supply terminal 32, and the arrangement of the third power supply terminal 43 and the fourth power supply terminal 44 are symmetrical with respect to the x-axis.

[0058] Figures 4 and 5 illustrate the temperature distribution on the wafer mounting surface 22 measured with a radiation thermometer when heating was performed in the multi-zone heater 10 and the asymmetric multi-zone heater 1010, respectively, with a set temperature of 550°C.

[0059] In the case of the multi-zone heater 10 according to this embodiment, as shown in Figure 4, the temperature distribution on the wafer mounting surface 22 was generally uniform, with a maximum temperature of 552.1°C and a minimum temperature of 548.9°C. That is, the temperature variation (the difference between the maximum and minimum temperatures) was within 3.2°C.

[0060] In contrast, in the case of the asymmetric multi-zone heater 1010 shown in Figure 5, the maximum temperature was 557.5°C and the minimum temperature was 547.7°C, confirming the existence of a localized high-temperature region, or hot spot A. The temperature variation reached 9.8°C. A comparison of Figure 3 and Figure 5 shows that the hot spot A is formed at the location of the first leader wire 41 and the second leader wire 42.

[0061] These results indicate that, in the multi-zone heater 10, providing the first lead wire 41 and the second lead wire 42 for supplying power to the outer zone heater 40 at positions on the axis of symmetry of the symmetrical arrangement of the lift pin holes 60 for the lift pins is preferable for ensuring uniform heat distribution on the wafer mounting surface 22.

[0062] Furthermore, from the standpoint of suppressing temperature variations caused by the presence of the first and second leader lines 41 and 42, it is desirable for the first and second leader lines 41 and 42 to be short. This means that it is desirable for the diameter of the virtual boundary circle 26 to be small. However, the shorter the first and second leader lines 41 and 42 are, the smaller the inner zone 20a becomes and the larger the outer zone 20b becomes, resulting in an imbalance between the two. From the viewpoint of appropriately balancing the heating of the inner zone 20a by the inner zone heater 30 and the heating of the outer zone 20b by the outer zone heater 40, it is preferable for the diameter of the virtual boundary circle 26 to be about 51% to 82% of the diameter of the ceramic substrate 20. If the diameter of the virtual boundary circle 26 is less than 51% of the diameter of the ceramic substrate 20, the outer zone heater 40 will heat areas other than the wafer edge, making it difficult to control the temperature of the edge portion, which is undesirable. On the other hand, if the diameter of the virtual boundary circle 26 exceeds 86% of the diameter of the ceramic substrate 20, a problem arises in which the temperature control performance in the outer zone 20b is significantly reduced. For example, if the diameter of the ceramic substrate 20 is 330 mm, the diameter of the virtual boundary circle 26 is preferably 200 mm to 260 mm. Here, the diameter of the virtual boundary circle 26 is defined as the average value (midpoint) of the PCD of the inner zone heater 30 located furthest from the axis center C and the PCD of the outer zone heater 40 located closest to the axis center C.

[0063] <Alternative form> Figure 6 is a schematic plan view of a multizone heater 10B, which is an alternative embodiment of the multizone heater 10 shown in Figure 1.

[0064] The multi-zone heater 10B has the same configuration as the multi-zone heater 10, except that it has three lift pin holes 60 (60a to 60c) provided in the inner zone 20a, and consequently the local curvature of the inner zone heater 30 and the outer zone heater 40 is different. That is, the arrangement of the first lead wire 41 and the second lead wire 42 is the same as that of the multi-zone heater 10.

[0065] The lift pin holes 60 should be concentric with the ceramic substrate 20 and located on a circle with a diameter of 46% to 88% of the diameter of the ceramic substrate 20. If the lift pin holes 60 are located on a circle that does not meet this diameter range, the support of the wafer by the lift pins will become unstable, and there is a risk of the wafer falling, which is undesirable. For example, if the diameter of the ceramic substrate 20 is 330 mm, it is preferable that the lift pin holes 60 be located on a circle with a diameter of 180 mm to 280 mm.

[0066] Figure 7 illustrates the temperature distribution on the wafer mounting surface 22 when heating is performed in the multi-zone heater 10B with a set temperature of 500°C, as measured by a radiation thermometer.

[0067] In the case of the multi-zone heater 10B shown in Figure 7, the temperature distribution on the wafer mounting surface 22 was generally uniform, with a maximum temperature of 499.2°C and a minimum temperature of 495.9°C. In other words, the temperature variation was within 3.3°C.

[0068] These results also indicate that providing the first lead wire 41 and the second lead wire 42 for supplying power to the outer zone heater 40 at positions on the axis of symmetry of the symmetrical arrangement of the lift pin holes 60 for the lift pins is preferable for ensuring uniform heat distribution on the wafer mounting surface 22.

[0069] Figure 8 is a schematic plan view of a multizone heater 10C, which is a further embodiment of the multizone heater 10 shown in Figure 1.

[0070] The multizone heater 10C has the same configuration as the multizone heater 10, except that the arrangement of the first power supply terminal 31 and the second power supply terminal 32, and the arrangement of the third power supply terminal 43 and the fourth power supply terminal 44 are not symmetrical with respect to the y-axis, and therefore the arrangement of the first leader line 41 and the second leader line 42 is not symmetrical with respect to the y-axis only in the range located inside the shaft 50 in a plan view.

[0071] However, if the arrangement of the first leader line 41 and the second leader line 42 is symmetrical with respect to the same axis of symmetry as the arrangement of the lift pin hole 60, the inner zone heater 30, and the outer zone heater 40, at least in the area located outside the shaft 50 in a plan view, then the uniformity of heating on the wafer mounting surface when heated by the heater can be improved. In other words, as in the multi-zone heater 10C, the asymmetrical arrangement of the first power supply terminal 31 and the second power supply terminal 32, and the asymmetrical arrangement of the third power supply terminal 43 and the fourth power supply terminal 44, and therefore the asymmetrical arrangement of the first leader line 41 and the second leader line 42 in the area located inside the shaft 50 in a plan view, does not affect the uniformity of heating on the wafer mounting surface 22.

[0072] In other words, this means that if the arrangement of the first leader line 41 and the second leader line 42, including the multi-zone heater 10 and the multi-zone heater 10B, is a line-symmetrical arrangement that shares a common axis of symmetry with the arrangement of the lift pin hole 60, the inner zone heater 30 and the outer zone heater 40, at least in the range located outside the shaft 50 in a plan view, then the uniformity of heating on the wafer mounting surface when heated by the heaters will be improved.

[0073] As described above, according to this embodiment, a multizone heater is provided which has a ceramic substrate on which one main surface is a semiconductor wafer mounting surface and through which a plurality of lift pin holes are provided for inserting lift pins for raising and lowering the semiconductor wafer, and in which the inner zone in the center of the ceramic substrate and the outer zone outside of it are independently heated by separate heaters, in addition to arranging the lift pin holes, the inner zone heater and the outer zone heater in a line-symmetrical arrangement with a common axis of symmetry, the lead wires that are responsible for supplying power to the outer zone heater are provided symmetrically along the axis of symmetry. In a multizone heater configured in this way, it is possible to improve the uniformity of heating on the wafer mounting surface when heated by the heater compared to a multizone heater in which the lead wires are not along the axis of symmetry.

[0074] <Variation> In the above-described embodiment, the lift pin holes 60 are provided at equal angular intervals on a circle concentric with the ceramic substrate 20, but configurations where the intervals are not equal are also acceptable. For example, the three lift pin holes may be arranged in an isosceles triangle shape, rather than an equilateral triangle, on a circle concentric with the ceramic substrate 20.

[0075] Furthermore, in the above-described embodiment, the first power supply terminal 31 and the second power supply terminal 32 are provided in the same plane, and the third power supply terminal 43 and the fourth power supply terminal 44 are provided in the same plane, and both the inner zone heater 30 and the outer zone heater 40 are arranged two-dimensionally in the xy plane.

[0076] Alternatively, the first power supply terminal 31 and the second power supply terminal 32 may be provided vertically along the z-axis direction, and the inner zone heater 30 may have a three-dimensional arrangement in which it is wired not only in the xy-plane but also in the z-axis direction. Similarly, the third power supply terminal 43 and the fourth power supply terminal 44 may also be provided vertically along the z-axis direction, and the outer zone heater 40 may have a three-dimensional arrangement in which it is wired not only in the xy-plane but also in the z-axis direction.

Claims

1. A multi-zone heater comprising a disc-shaped ceramic base having one main surface serving as a wafer mounting surface, the multi-zone heater being capable of heating a wafer mounted on the one main surface, a plurality of lift pin holes formed in the ceramic base, through which lift pins for lifting and lowering the wafer can be inserted; an inner zone heater embedded in the inner zone of the ceramic substrate; an outer zone heater embedded in an outer zone of the ceramic substrate that is outside the inner zone; a first power supply terminal and a second power supply terminal provided in a central portion of the ceramic base and connected to both ends of the inner zone heater; a first lead wire and a second lead wire connected to both ends of the outer zone heater; a third power supply terminal provided in a central portion of the ceramic base and connected to the first lead wire, and a fourth power supply terminal connected to the second lead wire; Equipped with the plurality of lift pin holes, the inner zone heater, and the outer zone heater are arranged in line symmetry with a common axis of symmetry; the first lead wire and the second lead wire are provided symmetrically to each other along the axis of symmetry; A multi-zone heater characterized by:

2. 2. The multi-zone heater of claim 1, the plurality of lift pin holes are provided on a circle concentric with the ceramic base; A multi-zone heater characterized by:

3. 3. The multi-zone heater of claim 2, The diameter of a circle concentric with the ceramic substrate is 46% to 88% of the diameter of the ceramic substrate. A multi-zone heater characterized by:

4. 4. The multi-zone heater according to claim 1, wherein: the inner zone and the outer zone are divided by an imaginary boundary circle that is concentric with the ceramic substrate, and the diameter of the boundary circle is 51% to 82% of the diameter of the ceramic substrate; A multi-zone heater characterized by:

Images