Ceramic Heater

Abstract

A multi-zone ceramic heater with jumpers is provided that is unlikely to be damaged during manufacture or use, and that can realize not only desirable thermal uniformity but also desirable temperature distribution profile when changing the power ratio of the inner zone / outer zone. The ceramic heater includes a ceramic plate including an inner zone defined as a circular region within a predetermined distance from the center of the ceramic plate and an outer zone defined as an annular region outside the inner zone, an inner zone heater circuit embedded in the inner zone of the ceramic plate, an outer zone heater circuit embedded in the outer zone of the ceramic plate, and a pair of jumpers embedded in the inner zone of the ceramic plate so as not to come into contact with the inner zone heater circuit and electrically connected to the outer zone heater circuit. The percentage of the resistance value of each jumper with respect to the resistance value of the outer zone heater circuit is 0.5 to 1.9%.

Description

[Technical field]

[0001] The present disclosure relates to ceramic heaters. [Background technology]

[0002] In a film forming apparatus for a semiconductor manufacturing process, a ceramic heater is used as a support stage for uniformly controlling the temperature of a wafer. A widely used ceramic heater includes a ceramic plate on which a wafer is placed and a cylindrical ceramic shaft attached to the ceramic plate. A multi-zone ceramic heater having multiple heating zones is also known as a ceramic heater.

[0003] The miniaturization and high layering for high integration of semiconductors is accelerating, and the semiconductor manufacturing process is becoming higher in temperature, longer in duration, and more powerful in plasma. As a result, the requirements for thermal uniformity of ceramic heaters are becoming increasingly strict.

[0004] On the other hand, in a multi-zone ceramic heater having two or more zones, which has an inner zone heater circuit and an outer zone heater circuit, a component called a jumper is used to ensure electrical connection from a power supply terminal near the center of the ceramic plate to the outer zone heater circuit. However, due to its structure, the jumper is likely to become a singular point of temperature distribution, which can cause a loss of thermal uniformity. For this reason, various measures have been proposed regarding the jumper from the viewpoint of improving thermal uniformity. Examples of such measures include (1) making the cross-sectional area of ​​the jumper relatively larger than the cross-sectional area of ​​the heater (see Patent Document 1 described below), (2) shortening the length of the jumper by making it as straight as possible (see Patent Document 2 described below), and (3) shortening the length of the jumper by reducing the area of ​​the inner zone and increasing the area of ​​the outer zone.

[0005] Patent Document 1 (JP Patent Publication No. 2018-537802) discloses a substrate heating device including a body portion that supports a substrate, a first heating element (inner zone heater circuit) located in an internal region of the body portion, a second heating element (outer zone heater circuit) located in an external region surrounding the internal region, and a third heating element (jumper) that transmits current to the second heating element across the internal region of the body portion, and it is stated that the diameter of the wire constituting the third heating element (jumper) is larger than the diameter of the wire constituting the second heating element (outer zone heater circuit).

[0006] Patent Document 2 (JP Patent Publication No. 4640842) discloses a heating device including a heater and a hollow support member fixed to the back surface of the heater. This heater is a plate-shaped base made of an insulating material, in which a first heating element, a second heating element, a first conductive connection portion, a first terminal portion, a second conductive connection portion, and a second terminal portion are embedded. The first heating element is provided on the periphery of the heater to form an outer zone heater circuit, while the second heating element is provided in the center of the heater together with the first terminal portion, the second terminal portion, and the second conductive connection portion to form an inner zone heater circuit. The first conductive connection portions are respectively connected to a plurality of ends of the first heating element corresponding to the outer zone heater circuit, and the first terminal portion is respectively connected to the first conductive connection portions. Therefore, the first conductive connection portions correspond to jumpers. The drawings of this document disclose a circuit pattern in which the length of the first conductive connection portions (jumpers) is shortened by configuring them in a straight line. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2018-537802 [Patent Document 2] Patent No. 4640842 Summary of the Invention

[0008] However, conventional multi-zone ceramic heaters equipped with jumpers can be damaged during manufacturing or use, or even if they do not, they can have problems such as not being able to achieve the desired thermal uniformity or making it difficult to achieve the desired temperature distribution profile when changing the power ratio of the inner zone / outer zone.

[0009] The inventors have now discovered that by setting the percentage of the resistance value per jumper relative to the resistance value of the outer zone heater circuit within the range of 0.5 to 1.9%, damage during manufacture or use is less likely to occur, and not only is desirable thermal uniformity achieved, but a desirable temperature distribution profile can also be achieved when changing the inner zone / outer zone power ratio.

[0010] Therefore, an object of the present invention is to provide a multi-zone ceramic heater with a jumper that is less likely to be damaged during manufacture or use, and that can achieve not only desirable thermal uniformity but also desirable temperature distribution profiles when changing the power ratio of the inner zone / outer zone.

[0011] According to the present disclosure, the following aspects are provided. [Aspect 1] A ceramic plate having a circular shape and a first surface on which a wafer is placed and a second surface opposite to the first surface, the ceramic plate including, when viewed from above, an inner zone defined as a circular region within a predetermined distance from a center of the ceramic plate, and an outer zone defined as an annular region outside the inner zone; an inner zone heater circuit embedded in the inner zone of the ceramic plate; an outer zone heater circuit embedded in the outer zone of the ceramic plate; a pair of jumpers embedded in the inner zone of the ceramic plate so as not to come into contact with the inner zone heater circuit and electrically connected to the outer zone heater circuit; Equipped with A ceramic heater, wherein the percentage of the resistance value of each of the jumpers with respect to the resistance value of the outer zone heater circuit is 0.5 to 1.9%. [Aspect 2] 2. The ceramic heater of embodiment 1, wherein the inner and outer zone heater circuits comprise resistive heating elements in at least one form selected from the group consisting of coils, linear zigzag structures, printed patterns, ribbons, and mesh. [Aspect 3] 3. The ceramic heater according to aspect 2, wherein the outer zone heater circuit includes a resistance heating element in a coil form having a winding diameter of 2.5 to 5.0 mm and a wire diameter of 0.3 to 0.7 mm. [Aspect 4] 4. The ceramic heater of aspect 2 or 3, wherein the outer zone heater circuit comprises a resistive heating element in the form of a linear zigzag structure having a maximum amplitude of 5 to 15 mm and a wire diameter of 0.3 to 0.7 mm. [Aspect 5] The ceramic heater according to any one of aspects 1 to 4, wherein the jumper includes a resistive heating element in at least one form selected from the group consisting of a line, a printed pattern, and a ribbon. [Aspect 6] The ceramic heater according to any one of aspects 1 to 5, wherein the outer zone is divided into a plurality of outer subzones, and the sum of resistance values ​​of the resistive heating elements embedded in the plurality of outer subzones is regarded as the resistance value of the outer zone heater circuit. [Aspect 7] The ceramic heater according to any one of aspects 1 to 6, wherein the ceramic plate comprises aluminum nitride or aluminum oxide. [Aspect 8] a pair of first power supply terminals provided at a central portion of the inner zone of the ceramic plate for supplying power to the inner zone heater circuit; a pair of second power supply terminals provided at a central portion of the inner zone of the ceramic plate for supplying power to the outer zone heater circuit via the jumper; The ceramic heater according to any one of aspects 1 to 7, further comprising: [Aspect 9] The ceramic heater according to any one of aspects 1 to 8, further comprising internal electrodes, which are RF electrodes and / or ESC electrodes, in the ceramic plate. [Aspect 10] The ceramic heater according to any one of aspects 1 to 9, further comprising a cylindrical ceramic shaft concentrically attached to the second surface of the ceramic plate and having an internal space. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective cross-sectional view showing a schematic example of a ceramic heater according to the present invention, in which the jumper 22 is drawn slightly lower than its actual position in order to clearly show the configurations of the inner zone control heater circuit 14a and the jumper 22, which are actually located at the same height, for convenience of explanation. [Diagram 2] FIG. 2 is a schematic top view of the ceramic heater shown in FIG. [Diagram 3] FIG. 4 is a perspective cross-sectional view that illustrates a schematic view of another example of a ceramic heater according to the present invention. [Figure 4] FIG. 4 is a schematic top view of the ceramic heater shown in FIG. [Figure 5A] FIG. 1 is a plan view showing a schematic diagram of the circuit patterns of the inner zone heater circuit, the outer zone heater circuit, and the jumpers employed in Examples 1 to 9 and 12. The lines corresponding to the circuit patterns in this drawing represent the center lines of the inner zone heater circuit, the outer zone heater circuit, and the jumpers. [Figure 5B] FIG. 5B is a plan view showing a schematic circuit pattern of the inner zone heater circuit shown in FIG. 5A. [Figure 5C] FIG. 5B is a plan view showing a schematic circuit pattern of the outer zone heater circuit and the jumper shown in FIG. 5A. [Figure 6A]1 is a plan view showing a schematic diagram of the circuit patterns of the inner zone heater circuit, the outer zone heater circuit, and the jumper employed in Examples 10 and 11. Each line corresponding to the circuit pattern in this drawing represents the center line of the inner zone heater circuit and the outer zone heater circuit. [Figure 6B] FIG. 6B is a plan view showing a schematic circuit pattern of the inner zone heater circuit shown in FIG. 6A. [Figure 6C] FIG. 6B is a plan view showing a schematic circuit pattern of the outer zone heater circuit and the jumper shown in FIG. 6A. [Figure 7] 1 is a graph showing the relationship between the percentage of the resistance value per jumper relative to the resistance value of the outer zone heater circuit and the maximum in-plane temperature difference (thermal uniformity) measured in various examples including Examples 1 to 6. [Figure 8] 13 shows the temperature profiles measured in Examples 1 to 6 when the outer / inner power ratio is changed to 1.4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The ceramic heater according to the present invention is a ceramic platform for supporting a wafer in a semiconductor manufacturing device. Typically, the ceramic heater according to the present invention can be a ceramic heater for a semiconductor film forming device. Typical examples of the film forming device include a CVD (chemical vapor deposition) device (e.g., a thermal CVD device, a plasma CVD device, a photo CVD device, and an MOCVD device) and a PVD (physical vapor deposition) device.

[0014] 1 and 2 show an embodiment of a ceramic heater. The ceramic heater 10 shown in FIG. 1 and 2 includes a ceramic plate 12, an inner zone heater circuit 14, an outer zone heater circuit 16, and a pair of jumpers 22. The ceramic plate 12 is disk-shaped and has a first surface 12a on which a wafer W is placed and a second surface 12b opposite to the first surface 12a. When viewed from above, the ceramic plate 12 includes an inner zone Z1 defined as a circular region within a predetermined distance from the center of the ceramic plate 12, and an outer zone Z2 defined as an annular region outside the inner zone Z1. The inner zone heater circuit 14 is embedded in the inner zone Z1 of the ceramic plate 12, while the outer zone heater circuit 16 is embedded in the outer zone Z2 of the ceramic plate. The pair of jumpers 22 are embedded in the inner zone Z1 of the ceramic plate 12 so as not to come into contact with the inner zone heater circuit 14, and are electrically connected to the outer zone heater circuit 16. The percentage of the resistance value of the jumpers 22 (per jumper) relative to the resistance value of the outer zone heater circuit 16 is 0.5 to 1.9%. By setting the percentage of the resistance value of the jumpers 22 (per jumper) relative to the resistance value of the outer zone heater circuit 16 within the range of 0.5 to 1.9% in this way, damage is less likely to occur during manufacture or use, and not only is desirable thermal uniformity achieved, but a desirable temperature distribution profile can also be achieved when changing the power ratio of the inner zone / outer zone.

[0015] As mentioned above, conventional multi-zone ceramic heaters equipped with jumpers may be damaged during manufacture or use, or even if they are not, they may not provide the desired thermal uniformity, or may be difficult to achieve the desired temperature distribution profile when the power ratio of the inner zone / outer zone is changed. For example, when a three-dimensional coil-type resistance heating element is used, increasing the jumper diameter as proposed in Patent Document 1 increases the thermal stress generated during manufacture or use, increasing the risk of damage. Also, when a resistance heating element with a linear zigzag structure is used, increasing the jumper diameter increases the risk of damage, as with a three-dimensional coil. Furthermore, if the size of the outer zone is relatively larger than that of the inner zone, there is a problem that the temperature distribution profile desired by the user (for example, a desire to selectively or preferentially increase the temperature of the outer periphery of the ceramic heater) cannot be achieved when the power ratio of the inner zone / outer zone of the two-zone heater is changed due to a change in process conditions, etc. This problem is successfully solved by the present invention.

[0016] In particular, while increasing the diameter of the jumper in the conventional technology can reduce the resistance of the jumper relative to the resistance of the outer zone heater circuit, it increases the risk of breakage due to thermal stress during manufacturing or use, making it difficult to actually use it. Therefore, in order to significantly increase the heating element density in the outer zone heater circuit, (i) in the case of a three-dimensional coil type resistance heating element, the coil winding diameter is increased, the coil wire diameter is reduced, and / or the number of coils is maximized (the coil pitch is reduced), (ii) in the case of a linear zigzag structure resistance heating element, the maximum swing width of the linear zigzag structure is increased, the wire diameter of the linear zigzag structure is reduced, and / or the number of zigzags is maximized (the pitch is reduced), and (iii) in the case of a printed pattern resistance heating element, the printing width is reduced, the printing thickness is reduced, and / or the printing pattern is made zigzag. In this way, it is possible to significantly reduce the ratio of the resistance of the jumper relative to the resistance of the outer zone heater circuit. This makes it possible to significantly suppress relative heat generation in the jumpers, and as a result, the thermal uniformity (temperature uniformity) of the ceramic heater 10 can be improved.

[0017] Specifically, the percentage of the resistance of the jumpers 22 (per one) relative to the resistance of the outer zone heater circuit 16 is 0.5 to 1.9%, preferably 0.5 to 1.1%, and more preferably 0.5 to 0.9%. Within these ranges, breakage during manufacture or use is unlikely to occur, and not only is desirable thermal uniformity achieved, but a desirable temperature distribution profile when changing the inner zone / outer zone power ratio can also be more effectively achieved.

[0018] The main portion of the ceramic plate 12 (i.e., the ceramic base) other than embedded members such as the inner zone heater circuit 14, the outer zone heater circuit 16, and the jumper 22 preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride, from the viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon.

[0019] 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, and may be an incomplete circle with a part missing, such as an orientation flat. The size of the ceramic plate 12 is not particularly limited and may be appropriately determined according to the diameter of the wafer to be used, but when it is circular, the diameter is typically 150 to 450 mm, and particularly for 300 mm silicon wafers, the diameter is typically 320 to 380 mm. The thickness of the ceramic plate 12 is typically 10 to 25 mm.

[0020] The ceramic plate 12 includes an inner zone Z1 and an outer zone Z2 when viewed from above. The inner zone Z1 is defined as a circular area within a predetermined distance from the center of the ceramic plate 12. The outer zone Z2 is defined as an annular area outside the inner zone Z1. The outer zone Z2 may be divided into a plurality of outer subzones (e.g., two to four divisions), and in this case, the total resistance value of the resistance heating elements embedded in the plurality of outer subzones is regarded as the resistance value of the outer zone heater circuit 16. For example, the outer zone Z2 may be composed of a plurality of outer subzones partitioned into an arc shape (e.g., two to four divisions) (for example, in FIG. 4, the outer zone Z2 is divided into two). Alternatively, the outer zone Z2 may have two or more concentric annular areas of different sizes that do not overlap each other. In this case, the outer zone Z2 has at least a first outer zone adjacent to the inner zone Z1 and a second outer zone located outside the first outer zone. Optionally, there may be a third or more outer zones outside the second outer zone.

[0021] The inner zone heater circuit 14 and the outer zone heater circuit 16 preferably include a resistance heating element having at least one form selected from the group consisting of a coil, a linear zigzag structure, a print pattern, a ribbon, and a mesh. The coil has a configuration in which a resistance heating wire is wound three-dimensionally, while the linear zigzag structure has a configuration in which a resistance heating wire is alternately folded back two-dimensionally in a plane. The print pattern is not particularly limited, but typically has a pattern in which strip-shaped lines of the resistance heating element layer alternately go straight and bend (for example, in a zigzag pattern). It is preferable to use resistance heating elements of the same form for the inner zone heater circuit 14 and the outer zone heater circuit 16 in terms of ease of fabrication, but resistance heating elements of different forms may also be used. Each of the inner zone heater circuit 14 and the outer zone heater circuit 16 is preferably arranged in a form of a single stroke when viewed in a plane. The form of the single stroke may be various known forms such as an alternating repetition of forward and reverse strokes, a spiral, etc.

[0022] The inner zone heater circuit 14 is embedded in the inner zone Z1 of the ceramic plate 12 parallel to the first surface 12a. A pair of first power supply terminals 18 for supplying power to the inner zone heater circuit 14 may be provided in the center of the inner zone Z1 of the ceramic plate 12. Preferably, the first power supply terminals 18 are connected to both ends of the inner zone heater circuit 14, respectively. There may be two or more pairs of the first power supply terminals 18. The first power supply terminals 18 are rod-shaped, and the inner zone heater circuit 14 is connected to a heater power source (not shown) via the rod-shaped first power supply terminals 18.

[0023] In a preferred embodiment of the present invention, the inner zone heater circuit 14 includes a resistance heating element in the form of a coil. In this case, the winding diameter of the coil is preferably 2.5 to 5.0 mm, more preferably 2.5 to 4.0 mm, and even more preferably 3.0 to 3.5 mm. The wire diameter of the coil is preferably 0.3 to 0.7 mm, more preferably 0.4 to 0.6 mm, and even more preferably 0.4 to 0.5 mm. In another preferred embodiment of the present invention, the inner zone heater circuit 14 includes a resistance heating element in the form of a linear zigzag structure. In this case, the maximum swing width of the linear zigzag structure is preferably 5 to 15 mm, more preferably 5 to 10 mm, and even more preferably 6 to 8 mm. The maximum swing width of the linear zigzag structure is defined as the distance between the line connecting the vertices on one side of the linear zigzag structure and the line connecting the vertices on the opposite side. The wire diameter of the linear zigzag structure is preferably 0.3 to 0.7 mm, more preferably 0.4 to 0.6 mm, and even more preferably 0.4 to 0.5 mm. In yet another preferred embodiment of the present invention, the inner zone heater circuit 14 includes a resistance heating element in the form of a printed pattern. In this case, the printing thickness of the printed pattern (thickness of the resistance heating element layer) is preferably 0.01 to 0.06 mm, more preferably 0.01 to 0.04 mm, and even more preferably 0.015 to 0.03 mm.

[0024] The outer zone heater circuit 16 is embedded in the outer zone Z2 of the ceramic plate 12 at the same or different depth as the inner zone heater circuit 14 and parallel to the first surface 12a. In a preferred embodiment of the present invention, as shown in Figs. 1 and 2, the outer zone heater circuit 16 may be embedded in the outer zone Z2 of the ceramic plate 12 at the same depth as the inner zone heater circuit 14 and parallel to the first surface 12a. In another preferred embodiment of the present invention, as shown in Figs. 3 and 4, the outer zone heater circuit 16 may be embedded in the outer zone Z2 of the ceramic plate 12 at a different depth than the inner zone heater circuit 14 and parallel to the first surface 12a. In Fig. 3, the inner zone heater circuit 14 is embedded above the outer zone heater circuit 16 (i.e., at a depth closer to the first surface 12a), but this is not limited thereto. Therefore, the inner zone heater circuit 14 may be embedded below the outer zone heater circuit 16 (i.e., at a depth closer to the second surface 12b). In either embodiment, a pair of second power supply terminals 20 for supplying power to the outer zone heater circuit 16 via a jumper 22 is provided in the center of the inner zone Z1 of the ceramic plate 12 (but at a position different from the first power supply terminals 18). That is, the pair of second power supply terminals 20 is disposed at a position away from the outer zone heater circuit 16, and therefore the pair of second power supply terminals 20 is electrically connected to the outer zone heater circuit 16 via the pair of jumpers 22. There may be two or more pairs of second power supply terminals 20. The second power supply terminals 20 are rod-shaped, and the outer zone heater circuit 16 is connected to a heater power source (not shown) via the jumper 22 and the rod-shaped second power supply terminals 20.

[0025] In a preferred embodiment of the present invention, the outer zone heater circuit 16 includes a resistance heating element in the form of a coil. In this case, the winding diameter of the coil is preferably 2.5 to 5.0 mm, more preferably 2.5 to 4.0 mm, and even more preferably 3.0 to 3.5 mm. The wire diameter of the coil is preferably 0.3 to 0.7 mm, more preferably 0.4 to 0.6 mm, and even more preferably 0.4 to 0.5 mm. In another preferred embodiment of the present invention, the outer zone heater circuit 16 includes a resistance heating element in the form of a linear zigzag structure. In this case, the maximum swing width of the linear zigzag structure is preferably 5 to 15 mm, more preferably 5 to 10 mm, and even more preferably 6 to 8 mm. The wire diameter of the linear zigzag structure is preferably 0.3 to 0.7 mm, more preferably 0.4 to 0.6 mm, and even more preferably 0.4 to 0.5 mm. In yet another preferred embodiment of the present invention, the outer zone heater circuit 16 includes a resistance heating element in the form of a printed pattern. In this case, the printing thickness of the printing pattern (thickness of the resistance heating element layer) is preferably 0.01 to 0.06 mm, more preferably 0.01 to 0.04 mm, and further preferably 0.015 to 0.03 mm. In any embodiment, if the dimensions are within the above range, the heating element density in the outer zone heater circuit can be significantly increased, and the ratio of the resistance value of the jumper 22 to the resistance value of the outer zone heater circuit 16 can be effectively reduced. In other words, the percentage of the resistance value of the jumper 22 (per jumper) to the resistance value of the outer zone heater circuit 16 can be easily adjusted to within a range of 0.5 to 1.9%, and as a result, breakage is less likely to occur during manufacture or use, and not only desirable thermal uniformity but also desirable temperature distribution profile when changing the power ratio of the inner zone / outer zone can be more effectively realized.

[0026] The outer zone heater circuit 16 may be either a series circuit or a parallel circuit. That is, the outer zone heater circuit 16 may be provided so as to start from one of the pair of jumpers 22 in one direction and reach the other of the pair of jumpers 22 in a single stroke so as to form a series circuit (see, for example, FIGS. 5A and 5C described later). Alternatively, the outer zone heater circuit 16 may be provided so as to start from one of the pair of jumpers 22 in two directions and reach the other of the pair of jumpers 22 in a single stroke for each starting direction so as to form a parallel circuit (see, for example, FIGS. 6A and 6C described later). The outer zone heater circuit 16 shown in FIG. 1 corresponds to this series circuit, while the outer zone heater circuit 16 shown in FIG. 3 corresponds to this parallel circuit.

[0027] A pair of jumpers 22 are embedded in the inner zone Z1 of the ceramic plate 12 so as not to come into contact with the inner zone heater circuit 14, and are electrically connected to the outer zone heater circuit 16. They may be embedded parallel to the first surface 12a at the same or different depth as the outer zone heater circuit 16. The pair of jumpers 22 are separated from each other, and one jumper 22 electrically connects one of the second power supply terminals 20 to one end of the outer zone heater circuit 16, while the other jumper 22 electrically connects the other of the second power supply terminals 20 to the other end of the outer zone heater circuit 16. Two or more pairs of jumpers 22 may be present.

[0028] The jumper 22 preferably includes a resistance heating element having at least one form selected from the group consisting of a line, a printed pattern, and a ribbon. The specific form of the line is not particularly limited, but typical examples include a straight line, a curved line (e.g., a circular arc), and a combination of a straight line and a curved line (e.g., a straight line partially bent with a curvature). In a preferred embodiment of the present invention, the jumper 22 is a linear resistance heating element (i.e., a resistance heating element wire). In this case, the wire diameter of the resistance heating element wire is preferably 0.3 to 0.7 mm, more preferably 0.4 to 0.7 mm, and even more preferably 0.5 to 0.7 mm. isIn another preferred embodiment of the present invention, the jumper 22 is a printed pattern. In this case, the printing thickness of the printed pattern (thickness of the resistance heating layer) is preferably 0.01 to 0.06 mm, more preferably 0.02 to 0.05 mm, and further preferably 0.025 to 0.04 mm.

[0029] The pair of jumpers 22 and the pair of second power supply terminals 20 are preferably arranged symmetrically with respect to the perpendicular bisector of the line segment connecting the pair of second power supply terminals 20 when the ceramic plate 12 is viewed in a plan view. With this configuration, the lengths of the power supply paths from the pair of second power supply terminals 20 through the pair of jumpers 22 to the outer zone heater circuit 16 can be made equal, making it easier to achieve good heat uniformity.

[0030] The ceramic plate 12 may further include an RF electrode 30 and / or an ESC electrode. In this case, the RF electrode 30 and / or the ESC electrode are preferably embedded in the ceramic plate 12 at a depth position closer to the first surface 12a than the inner zone heater circuit 14 and the jumper 22. The RF electrode enables film formation by a plasma CVD process by applying a high frequency. The ESC electrode is an abbreviation of an electrostatic chuck (ESC) electrode, and is also called an electrostatic electrode. When a voltage is applied to the ESC electrode by an external power source, the ESC electrode chucks a wafer placed on the surface of the ceramic plate 12 by the Johnsen-Rahbek force. The ESC electrode is preferably a circular thin-layer electrode having a slightly smaller diameter than the ceramic plate 12, and may be, for example, a mesh-like electrode formed by weaving thin metal wires into a net shape into a sheet shape. The ESC electrode may be used as a plasma electrode. That is, by applying a high frequency to the ESC electrode, the ESC electrode can also be used as an RF electrode, and film formation can also be performed by a plasma CVD process. An RF terminal 32 or an ESC terminal for power supply is connected to the RF electrode 30 or the ESC electrode. The RF terminal 32 or the ESC terminal is rod-shaped, and the RF electrode 30 or the ESC electrode is connected to an external power supply (not shown) via the rod-shaped RF terminal 32 or the ESC terminal.

[0031] If desired, the ceramic shaft 28 may be concentrically attached to the second surface 12b of the ceramic plate 12. The ceramic shaft 28 is a cylindrical member having an internal space S, and may have the same configuration as a ceramic shaft used in a known ceramic susceptor or ceramic heater. The internal space S is configured so that terminal rods such as the first power supply terminal 18, the second power supply terminal 20, and the RF terminal 32 pass therethrough. The ceramic shaft 28 is preferably made of the same ceramic material as the ceramic plate 12. Therefore, the ceramic shaft 28 preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride. The upper end surface of the ceramic shaft 28 is preferably bonded to the second surface 12b of the ceramic plate 12 by solid-state bonding or diffusion bonding. The outer diameter of the ceramic shaft 28 is not particularly limited, but is preferably 40 to 60 mm. The inner diameter of the ceramic shaft 28 (diameter of the internal space S) is also not particularly limited, but is preferably 33 to 55 mm. EXAMPLES

[0032] The present invention will be described in more detail with reference to the following examples, although the present invention is not limited to the following examples.

[0033] Examples 1 to 9 and 12 (1) Preparation of ceramic heater Using the components shown below, a ceramic heater 10 having a structure as shown in FIGS. 1 and 2 was produced by a known procedure except for the firing conditions. <Components and their specifications> Ceramic plate 12: Disk-shaped aluminum nitride sintered body (diameter: 330 mm, thickness: 20 mm) (with inner zone heater circuit 14, outer zone heater circuit 16, jumper 22, and RF electrode 30 embedded inside) Ceramic shaft 28: Cylindrical aluminum nitride sintered body (height: 172 mm, outer diameter: 47 mm, inner diameter: 36 mm) Inner zone Z1: a circular area with a diameter of 216 mm located in the center of the ceramic plate 12 Outer zone Z2: an annular area of ​​the ceramic plate 12 outside the inner zone Z1 Inner zone heater circuit 14: A three-dimensional coil-shaped resistance heating element (Examples 1 to 5, 8 and 9, material: molybdenum, winding diameter and wire diameter: as shown in Table 1) embedded at a depth of 6.5 mm from the first surface 12a of the inner zone Z1 according to the circuit pattern shown in FIGS. 5A and 5B, or a resistance heating element with a linear zigzag structure (Examples 6 and 7, material: molybdenum, wire diameter and maximum fluctuation width of heating element (maximum fluctuation width of zigzag structure): as shown in Table 1) Outer zone heater circuit 16: A three-dimensional coil-shaped resistance heating element (Examples 1 to 5, 8 and 9, material: molybdenum, winding diameter and wire diameter: as shown in Table 1) embedded at a depth of 6.5 mm from the first surface 12a of the outer zone Z2 according to the circuit pattern shown in FIGS. 5A and 5C, or a resistance heating element with a linear zigzag structure (Examples 6 and 7, material: molybdenum, wire diameter and maximum fluctuation width of heating element (maximum fluctuation width of zigzag structure): as shown in Table 1) Jumper 22: A pair of substantially linear symmetrical resistance heating wires (material: molybdenum, wire diameter: 0.7 mm) buried at a depth of 6.5 mm from the first surface 12a in the inner zone Z1 according to the circuit pattern shown in FIGS. 5A and 5C (although the jumper 22 is depicted as being linear in FIGS. 5A and 5C, it is actually substantially linear with some curved portions as shown in FIG. 2). RF electrode 30: An electrode layer made of molybdenum embedded at a depth of 1.0 mm from the first surface 12a of the ceramic plate 12. First power supply terminal 18: Two terminal rods made of nickel Second power supply terminal 20: Two terminal rods made of nickel RF terminal 32: 1 terminal rod made of nickel

[0034] The ceramic plate 12 in which the above-mentioned inner zone heater circuit 14, outer zone heater circuit 16, jumper 22, and RF electrode 30 are embedded is manufactured by the following procedure. First, aluminum nitride powder is press molded to obtain a first aluminum nitride compact. On the obtained first aluminum nitride compact, aluminum nitride powder, the inner zone heater circuit 14, the outer zone heater circuit 16, and the jumper 22 are arranged according to the circuit patterns shown in Figs. 5A to 5C, and press molded to obtain a second aluminum nitride compact in which the inner zone heater circuit 14, the outer zone heater circuit 16, and the jumper 22 are embedded. On the obtained second aluminum nitride compact, aluminum nitride powder and the RF electrode 30 are arranged and press molded to obtain a third aluminum nitride compact in which the RF electrode 30 is further embedded. In this way, a press-molded body was obtained consisting of an aluminum nitride powder compact in which the inner zone heater circuit 14, the outer zone heater circuit 16, the jumper 22, and the RF electrode 30 were embedded, as shown in Fig. 2. The obtained press-molded body (laminate) was sintered in a nitrogen atmosphere under the following conditions: ·Maximum temperature: 1810℃ Maximum temperature hold time: 5 hours Heating rate: Vary within the range of 10 to 120°C / min (including individual heating rates in multiple heating steps) Fast degree range) Firing pressure: 90kg / cm 2 By firing at this temperature, a ceramic plate 12 was obtained in which the inner zone heater circuit 14, the outer zone heater circuit 16, the jumper 22, and the RF electrode 30 were embedded.

[0035] (2) Evaluation The obtained ceramic heater was subjected to various evaluations.

[0036] <Jumper / Outer Heater Resistance Ratio> At room temperature, the resistance value of the outer zone heater circuit 16 and the resistance value of each jumper 22 were measured. The resistance value of the outer zone heater circuit 16 was measured by connecting a four-terminal tester to both ends of the outer zone heater circuit 16. The resistance value of each jumper 22 was measured by connecting a four-terminal tester to both ends of each of a pair (i.e., two) jumpers 22, and the average of the two obtained resistance values ​​was calculated. The resistance value of each jumper 22 was divided by the resistance value of the outer zone heater circuit 16 and multiplied by 100 to obtain the percentage of the resistance value per jumper to the resistance value of the outer zone heater circuit (hereinafter referred to as the jumper / outer heater resistance ratio). The results are shown in Table 1.

[0037] <Heat uniformity> The ceramic heater 10 was placed in the chamber of the film forming apparatus. The chamber was evacuated and N2 gas was introduced to set the N2 gas pressure in the chamber to 5 Torr. The ceramic heater 10 was heated to a set temperature of 550°C by supplying power to the inner zone heater circuit 14 and the outer zone heater circuit 16 via the first power supply terminal 18, the second power supply terminal 20, and the jumper 22. At this time, the ratio of the power supplied to the outer zone heater circuit 16 and the power supplied to the inner zone heater circuit 14 was finely adjusted to obtain the most uniform temperature distribution while keeping the ratio at 1:1 as a standard. At this set temperature, the temperature distribution on the first surface 12a of the ceramic plate 12 was measured with an infrared camera. Based on the obtained temperature distribution map, the difference between the maximum temperature and the minimum temperature in the plane (i.e., the maximum temperature difference in the plane) was obtained as an index of thermal uniformity. The results were as shown in Table 1. FIG. 7 shows the relationship between the obtained maximum temperature difference in the plane and the jumper / outer heater resistance ratio. However, for Example 12, the ceramic heater 10 was broken during the evaluation, and therefore it was not possible to evaluate the thermal uniformity and the temperature profile described below.

[0038] <Temperature profile when changing the outer / inner power ratio> The ceramic heater 10 was heated to a set temperature of 550°C (the temperature measured by the thermocouple 36 in the inner zone Z1) in the same manner as in the evaluation of thermal uniformity, except that the outer zone heater circuit 16 was supplied with 1.3 to 1.5 times the power of the inner zone heater circuit 14 (i.e., the outer / inner power ratio was changed) to promote preferential temperature rise in the outer zone Z2. At this set temperature, the temperature distribution on the first surface 12a of the ceramic plate 12 was measured with an infrared camera. In the obtained temperature distribution map, an arbitrary straight line passing through the center of the ceramic plate 12 was set as the X-axis, and the center of the ceramic plate 12 was set as the reference point (X=0 mm) of the X-coordinate axis. The temperatures at various positions (radial positions) including the inner zone Z1 and the outer zone Z2 on the X-axis coordinate of the ceramic plate 12 were read from the temperature distribution map, and the central temperature at X=0 mm was subtracted from the temperatures at the various positions read, to obtain the temperature difference as the temperature increase. The temperature difference at each position was plotted in relation to the position on the X-axis coordinate to set an approximate curve, and a temperature profile was obtained. The quality of the obtained temperature profile was evaluated according to the following criteria. The results are shown in Table 1 and Figure 8. [Evaluation Criteria] Good: The temperature profile is roughly symmetrical, and while excessive temperature rise is suppressed in the middle of the ceramic plate 12 (the region where the absolute value of X is around 60 to 130 mm), the temperature rises at a higher temperature gradient (the slope of the tangent line drawn to the approximate curve of the temperature profile) toward the periphery. Poor: Does not meet the criteria for "good" above (i.e., the temperature profile is asymmetric and / or there is an excessive temperature rise in the middle (e.g. a higher temperature gradient than near the periphery)).

[0039] Examples 10 and 11 (1) Preparation of ceramic heater Using the components shown below, a ceramic heater 10 having a structure as shown in FIGS. 3 and 4 was produced by a known procedure except for the firing conditions. <Components and their specifications> Ceramic plate 12: Disk-shaped aluminum nitride sintered body (diameter: 330 mm, thickness: 20 mm) (with inner zone heater circuit 14, outer zone heater circuit 16, jumper 22, and RF electrode 30 embedded inside) Ceramic shaft 28: Cylindrical aluminum nitride sintered body (height: 172 mm, outer diameter: 60 mm, inner diameter: 51 mm) Inner zone Z1: a circular area with a diameter of 216 mm located in the center of the ceramic plate 12 Outer zone Z2: an annular area of ​​the ceramic plate 12 outside the inner zone Z1 Inner zone heater circuit 14: a printed pattern (zigzag, printing thickness: as shown in Table 1) consisting of a resistance heating element embedded according to the circuit pattern shown in FIGS. 6A and 6B at a depth of 6.5 mm from the first surface 12a of the inner zone Z1. Outer zone heater circuit 16: a printed pattern of a parallel circuit composed of resistive heating elements embedded at a depth of 11 mm from the first surface 12a of the outer zone Z2 according to the circuit pattern shown in Figures 6A and 6C (zigzag shape, printing thickness: as shown in Table 1) Jumper 22: A symmetrical print pattern (print thickness: 0.03 mm) consisting of a resistance heating element embedded in the region shown in Figures 6A and 6C at a depth of 11 mm from the first surface 12a of the inner zone Z1. Resistance heating element: Tungsten carbide-titanium nitride composite (common to inner zone heater circuit 14, outer zone heater circuit 16 and jumper 22) RF electrode 30: An electrode layer made of molybdenum embedded at a depth of 1.0 mm from the first surface 12a of the ceramic plate 12. First power supply terminal 18: Two terminal rods made of nickel Second power supply terminal 20: Two terminal rods made of nickel RF terminal 32: 1 terminal rod made of nickel

[0040] The ceramic plate 12 with the inner zone heater circuit 14, the outer zone heater circuit 16, the jumper 22, and the RF electrode 30 embedded therein was fabricated by the following procedure. First, two disk-shaped aluminum nitride sintered bodies were prepared. The inner zone heater circuit 14 was printed on one of the aluminum nitride sintered bodies according to the circuit pattern shown in Figs. 6A and 6B. The outer zone heater circuit 16 and the jumper 22 were printed on the other aluminum nitride sintered body according to the circuit pattern shown in Figs. 6A and 6C. Next, the aluminum nitride powder and the RF electrode 30 were press molded to obtain an aluminum nitride compact with the RF electrode 30 embedded therein. This aluminum nitride compact and the aluminum nitride sintered body with the above-mentioned printed pattern were stacked and press molded to form the layer structure shown in Fig. 4. The obtained press molded body (laminate) was sintered in a nitrogen atmosphere under the following conditions: ·Maximum temperature: 1810℃ Maximum temperature hold time: 5 hours Heating rate: Vary within the range of 10 to 120°C / min (including individual heating rates in multiple heating steps) Fast degree range) Firing pressure: 90kg / cm 2 By firing at this temperature, a ceramic plate 12 was obtained in which the inner zone heater circuit 14, the outer zone heater circuit 16, the jumper 22, and the RF electrode 30 were embedded.

[0041] (2) Evaluation The ceramic heater thus obtained was evaluated in the same manner as in Example 1.

[0042] [Table 1]

[0043] Separately from the above example, an attempt was made to fabricate ceramic heaters using molybdenum coils with a wire diameter of 0.2 mm for the inner zone heater circuit 14 and the outer zone heater circuit 16. However, the coil broke during fabrication and was significantly deformed, so the coil could not be used.

[0044] The results shown in Table 1 and Figures 7 and 8 reveal the following. Examples 1 and 2 (comparison) are comparative examples in which the jumper / outside heater resistance ratio exceeds 2%, and the maximum in-plane temperature difference exceeds 5°C at the evaluation temperature of 550°C, indicating poor thermal uniformity. In addition, when the outside / inside power ratio is changed to 1.4, as shown in Figure 8 As shown in Fig. 1, an undesirable temperature profile with poor left-right symmetry was obtained. Example 3 (comparison) is a comparative example with a low jumper / outer heater resistance ratio of 0.3%, and although it showed good thermal uniformity (maximum in-plane temperature difference of 5.0°C or less), when the outer / inner power ratio was changed to 1.4, the temperature profile was not as good as that shown in Fig. 8 As shown in FIG. 8, an undesirable temperature profile was obtained in which an excessive temperature rise (higher temperature gradient than near the periphery) was observed in the middle part (region where the absolute value of X is about 60 to 130 mm) rather than the outer periphery. Examples 4 to 11 are examples in which the jumper / outer heater resistance ratio is in the range of 0.5 to 1.9%, and good thermal uniformity (maximum temperature difference within the surface of 5.0°C or less) and a desirable temperature profile when the power ratio is changed were achieved. That is, as shown in FIG. 8, the temperature profile when the power ratio is changed was a desirable profile that was symmetrical and suppressed an excessive temperature rise in the middle part of the ceramic plate 12 (region where the absolute value of X is about 60 to 130 mm) while increasing the temperature with a higher temperature gradient as it approaches the periphery. In the ceramic heater industry, ceramic heaters that not only have good thermal uniformity but also exhibit a temperature profile in which the temperature rises preferentially in the outer periphery are often desired, and it can be said that the ceramic heaters of Examples 4 to 11 fully meet such needs.

Claims

1. A ceramic plate having a circular shape and a first surface on which a wafer is placed and a second surface opposite to the first surface, the ceramic plate including, when viewed from above, an inner zone defined as a circular region within a predetermined distance from a center of the ceramic plate, and an outer zone defined as an annular region outside the inner zone; an inner zone heater circuit embedded in the inner zone of the ceramic plate; an outer zone heater circuit embedded in the outer zone of the ceramic plate; a pair of jumpers embedded in the inner zone of the ceramic plate so as not to contact the inner zone heater circuit and electrically connected to the outer zone heater circuit; Equipped with A ceramic heater, wherein the percentage of the resistance of each of said jumpers relative to the resistance of said outer zone heater circuit is 0.5 to 1.9%.

2. 10. The ceramic heater of claim 1, wherein the inner and outer zone heater circuits comprise resistive heating elements in at least one form selected from the group consisting of coils, linear zigzag structures, printed patterns, ribbons, and meshes.

3. 3. The ceramic heater of claim 2, wherein the outer zone heater circuit comprises a resistive heating element in the form of a coil having a winding diameter of 2.5 to 5.0 mm and a wire diameter of 0.3 to 0.7 mm.

4. 3. The ceramic heater of claim 2, wherein the outer zone heater circuit comprises a resistive heating element in the form of a linear zigzag structure having a maximum amplitude of 5 to 15 mm and a wire diameter of 0.3 to 0.7 mm.

5. The ceramic heater according to any one of claims 1 to 4, wherein the jumper comprises a resistive heating element in at least one form selected from the group consisting of a line, a printed pattern, and a ribbon.

6. The ceramic heater according to any one of claims 2 to 4, wherein the outer zone is divided into a plurality of outer subzones, and the sum of resistance values ​​of the resistive heating elements embedded in the plurality of outer subzones is regarded as the resistance value of the outer zone heater circuit.

7. The ceramic heater according to any one of claims 1 to 4, wherein the ceramic plate comprises aluminum nitride or aluminum oxide.

8. a pair of first power supply terminals provided at a central portion of the inner zone of the ceramic plate for supplying power to the inner zone heater circuit; a pair of second power supply terminals provided at a central portion of the inner zone of the ceramic plate for supplying power to the outer zone heater circuit via the jumper; The ceramic heater according to any one of claims 1 to 4, further comprising:

9. The ceramic heater according to any one of claims 1 to 4, further comprising an internal electrode within the ceramic plate, the internal electrode being an RF electrode and / or an ESC electrode.

10. 5. The ceramic heater according to claim 1, further comprising a cylindrical ceramic shaft concentrically attached to the second surface of the ceramic plate and having an internal space.

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