JP6877301B2 - Ceramic heater - Google Patents

Description

The present invention relates to a ceramic heater that heats an object to be heated such as a semiconductor wafer.

In ceramic heaters that heat objects to be heated such as semiconductor wafers, there are ceramic heaters in which a plurality of heat generating resistors are independently embedded inside the substrate and the current supplied to each heat generating resistor can be controlled independently. It is disclosed that the number of terminals is reduced by connecting a plurality of heat generating resistors to at least one terminal (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-160368

However, in the above-mentioned conventional ceramic heater, power supply terminals for supplying an electric current are connected to both ends of each heat generating resistor, and these power supply terminals are inside a hollow support member connected to the lower surface of the substrate. Must be located in. As the number of heat generating resistors increases, the diameter of the support member increases because such a power feeding terminal is positioned in the support member. However, when the diameter of the support member is increased and the joint area between the support member and the substrate is increased, the heat escaping from the substrate through the support member increases, which is not preferable.

The present invention has been made in view of such circumstances, and a ceramic heater capable of suppressing an increase in the number of feeding terminals as compared with an increase in the area of a heating resistor in which the supplied current can be changed is provided. The purpose is to provide.

The present invention is made of ceramics, a ceramic substrate on which an object to be heated is placed on the upper surface, a heat generating resistor built in the ceramic substrate, and ceramics, and is connected to the central portion of the lower surface of the ceramic substrate. A ceramic heater provided with a tubular support member, wherein the heat generation resistor is composed of three or more heat generation resistance element groups, each of which is composed of one or more heat generation resistance elements. At least three of the three or more heat generation resistance element groups have direct ends at both ends of the other one of the at least three heat generation resistance element groups. It is characterized in that at least a power feeding terminal for supplying electric power is connected to a total of three ends including both ends.

According to the present invention, when power is supplied to the power supply terminal, for example, AC power, the current flowing through each heat generation resistance element group is generated by using a power adjusting means such as a three-phase power regulator (three-phase thyristor). It becomes possible to control so as to be separate. As a result, it is possible to control the heat generation in each heat generation resistance element group separately, and it is possible to reduce the number of power supply terminals as compared with the above-mentioned conventional ceramic heater, and by extension, the inner diameter of the support member. The diameter can be reduced.

In addition to using the three-phase power regulator, a power regulator that adjusts the power supplied to each power supply terminal by switching DC power or single-phase AC power may be used.

The heat generation resistor may have one or one or more heat generation resistance elements connected in series or in parallel.

In the present invention, the at least three heat generation resistance element groups are three heat generation resistance element groups, and the three heat generation resistance element groups are located at both ends of the three heat generation resistance element groups, respectively, and the other one of the three heat generation resistance element groups. The ends of the heat generation resistance element group are directly connected, and a total of three ends including the both ends are grounded via the heat generation resistance element group different from the three heat generation resistance element groups. Is preferable.

Further, in the present invention, the at least three heat generation resistance element groups are four heat generation resistance element groups, and the four heat generation resistance element groups are located at both ends of the four heat generation resistance element groups, respectively. The ends of the one heat-generating resistance element group of the above are directly connected, and the both ends are each of the other one heat-generating resistance element different from the four heat-generating resistance element groups connected to the both ends. It may be connected to the end of the group.

The schematic sectional view of the ceramics heater which concerns on 1st Embodiment of this invention. FIG. 1 is a schematic cross-sectional view taken along the line IIA-IIA of FIG. FIG. 1 is a schematic cross-sectional view taken along the line IIB-IIB of FIG. Schematic equivalent circuit diagram of a heating resistor. The schematic sectional view of the heat generation resistor which concerns on 2nd Embodiment of this invention. Schematic equivalent circuit diagram of a heating resistor. FIG. 3 is a schematic cross-sectional view of a lower heat generating resistor according to a third embodiment of the present invention. Schematic cross-sectional view of the middle heat generating resistor. Schematic cross-sectional view of the upper heating resistor. Schematic equivalent circuit diagram of a heating resistor. Schematic bottom view of the ceramic heater according to the embodiment. Schematic bottom view of the ceramic heater according to the comparative example. The graph which shows the waveform of the voltage supplied between the terminals between OXs in an Example. The graph which shows the waveform of the voltage supplied between the terminals between OYs in an Example. The graph which shows the waveform of the voltage supplied between the terminals between OZs in an Example. Schematic equivalent circuit diagram of another example of a heating resistor.

[First Embodiment]
The ceramic heater 100 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

As shown in FIG. 1, the ceramic heater 100 has a base 10 made of a substantially disk-shaped insulator for holding a wafer (board) (not shown), and heat generation embedded in the base 10 so as not to short-circuit each other. It includes a resistor 20 and a hollow shaft (support member) 30 connected to a central portion of the lower surface of the substrate 10.

The shaft 30 has a substantially cylindrical shape, has an enlarged diameter portion 32 in which the outer diameter of the joint portion with the base 10 is larger than that of the other cylindrical portion 31, and the upper surface of the enlarged diameter portion 32 is a joint surface with the base 10. It has become. The material of the shaft 30 may be the same as the material of the substrate 10, but may be formed of a material having a lower thermal conductivity than the material of the substrate 10 in order to improve the heat insulating property.

The lower surface of the substrate 10 and the upper end surface of the shaft 30 are bonded by diffusion bonding or solid phase bonding using a bonding material such as ceramics or glass. The substrate 10 and the shaft 30 may be connected by screwing or brazing.

In addition to the heat generating resistor 20, at least one of an electrostatic chuck electrode for attracting the wafer to the mounting surface by Coulomb force and a plasma electrode for generating plasma above the substrate 10 is embedded in the substrate 10. It may have been done.

Further, the ceramic heater 100 also serves as an electrostatic chuck that sucks the substrate onto the surface of the substrate 10 by the Coulomb force generated by applying a voltage from the feeding rod to the electrodes through an appropriate low-pass or high-pass filter. You may.

Further, the ceramic heater 100 includes three power supply terminals 40 for supplying electric power to the heat generating resistor 20.

Each of the power supply terminals 40 is connected to a power supply member (not shown) embedded in the substrate 10, and the power supply member is connected to a conducting wire that inserts the inside of the shaft 30. The power feeding terminal 40 itself may be inserted through the inside of the shaft 30 and connected to the conducting wire outside the shaft 30.

The power supply terminal 40 and the power supply member are brazed or welded. The power supply terminal 40 is made of foil, plate, massive nickel (Ni), Kovar (registered trademark) (Fe-Ni-Co), molybdenum (Mo), tungsten (W), or molybdenum (Mo) and tungsten (W). It is composed of heat-resistant metal such as heat-resistant alloy as the main component. The feeding member is made of molybdenum (Mo), tungsten (W) or the like.

The substrate 10 is, for example, a ceramics sintered body made of alumina, aluminum nitride, silicon nitride, or the like. The substrate 10 may be formed into a disk shape by, for example, hot press firing or the like in order to mold the above material in a mold having a predetermined shape and densify the substrate 10.

In the present embodiment, the heat generating resistor 20 is made of a foil of a heat-resistant metal such as molybdenum (Mo) or tungsten (W), and has a flat shape. However, the heat generating resistor 20 may have a structure such as a film made of a heat-resistant metal, a plate, a wire, a mesh, a fiber, a coil, or a ribbon.

The substrate 10 is fired with the heat generating resistor 20 sandwiched between the substrates 10.

An example of the pattern of the heat generating resistor 20 will be described mainly with reference to FIGS. 2A and 2B.

With reference to FIG. 1, the heat generation resistor 20 includes a lower heat generation resistor 21 and an upper heat generation resistor 22 arranged above the lower heat generation resistor 21.

Here, one end of the lower heat generating resistor 21 is directly connected to each other at the central portion O, and the other end portions A1, B1 and C1 are directly connected to separate power supply terminals 40 near the central portion O. It is composed of three heat generation resistance element groups 21A, 21B, and 21C that are connected to each other.

As shown in FIG. 2A, the heat generation resistance element group 21A is within the fan-shaped region from 0 o'clock to 4 o'clock, with the direction in which the linear heat generation resistance element 21A1a extends linearly from the central portion O toward the peripheral side as the 0 o'clock direction. Exists in. The heat generation resistance element group 21A is configured by connecting two linear heat generation resistance elements 21A1a and 21A1b, three arcuate heat generation resistance elements 21A2a to 21A2c, and two linear heat generation resistance elements 21A3a and 21A3b in series. ing.

Specifically, the linear heat generation resistance element 21A1a extends linearly from the central portion O to the peripheral portion in the direction of 0 o'clock. The edge on the peripheral edge side of the linear heat generation resistance element 21A1a opposite to the central portion O is the 0 o'clock side of the arcuate heat generation resistance element 21A2a extending clockwise from 0 o'clock to 4 o'clock in an arc shape. It is connected to the end of. The end of the arc-shaped heat-generating resistance element 21A2a on the 4 o'clock side is connected to the end of the linear heat-generating resistance element 21A3a on the central portion O side extending in a short straight line from this end toward the peripheral edge. There is. Then, the peripheral end of the linear heat generation resistance element 21A3a is connected to the 4 o'clock end of the arcuate heat generation resistance element 21A2b extending in an arc shape from 4 o'clock to 0 o'clock counterclockwise. Has been done.

The end of the arc-shaped heat-generating resistance element 21A2b on the 0 o'clock side is connected to the end of the linear heat-generating resistance element 21A3b on the O-side at the center, which extends in a short straight line from this end toward the peripheral edge. There is. The peripheral end of the linear heat generation resistance element 21A3b is connected to the end of the arcuate heat generation resistance element 21A2c extending clockwise from 0 o'clock to 4 o'clock on the 0 o'clock side. ing. The end of the arc-shaped heat-generating resistance element 21A2c on the 4 o'clock side is connected to the peripheral end of the linear heat-generating resistance element 21A1b extending in a long straight line from this end to the central portion O. There is. The linear heat generation resistance element 21A1b extends linearly from this end portion to the end portion A1 located near the central portion O in the 2 o'clock direction.

The heat generation resistance element group 21B exists in the fan-shaped region from 8:00 to 12:00. The heat generation resistance element group 21B is configured by connecting two linear heat generation resistance elements 21B1a and 21B1b, three arcuate heat generation resistance elements 21B2a to 21B2c, and two linear heat generation resistance elements 21B3a and 21B3b in series. ing.

The heat generation resistance element group 21C exists in the fan-shaped region from 4 o'clock to 8 o'clock. The heat generation resistance element group 21C is configured by connecting two linear heat generation resistance elements 21C1a and 21C1b, three arcuate heat generation resistance elements 21C2a to 21C2c, and two linear heat generation resistance elements 21C3a and 21C3b in series. ing.

Since the specific configuration of the heat generation resistance element groups 21B and 21C is the same as that of the heat generation resistance element group 21A, the description thereof will be omitted.

On the other hand, the upper heat generating resistor 22 has three heat generating resistors whose ends are directly connected to the other ends and the ends A2, B2, and C2 are directly connected to separate power feeding terminals 40. The element groups 22A, 22B, and 22C are connected to each other.

The heat generation resistance element group 22A exists in the fan-shaped region from 0:00 to 4:00. In the heat generation resistance element group 22A, one linear heat generation resistance element 22A1, four arcuate heat generation resistance elements 22A2a to 21A2d, four linear heat generation resistance elements 22A3a to 22A3d, and one linear communication heat generation resistance element 22A4 are connected in series. It is configured by being connected to.

Specifically, the linear heat generation resistance element 22A3a extends in a short linear direction from the end A2 located directly above the end A1 and directly connected to the end A1 toward the peripheral edge in the 0 o'clock direction. doing. The peripheral end of the linear heat generation resistance element 22A3a extends from this end clockwise in an arc shape from 0 o'clock to 4 o'clock to the end of the arcuate heat generation resistance element 22A2a on the 0 o'clock side. It is connected. The end portion of the arc-shaped heat generation resistance element 22A2a on the 4 o'clock side is the end portion on the central portion side of the linear heat generation resistance element 22A3b extending in a short linear direction from this end portion toward the peripheral edge portion in the direction of 4 o'clock. Is connected. The peripheral end of the linear heat generation resistance element 22A3b is connected to the 4 o'clock end of the arcuate heat generation resistance element 22A2b extending counterclockwise in an arc shape from 4 o'clock to 0 o'clock. Has been done.

The end portion of the arc-shaped heat generation resistance element 22A2b on the 0 o'clock side is located at the end portion on the central portion side of the linear heat generation resistance element 22A3c extending in a short linear shape in the 0 o'clock direction from this end portion toward the peripheral edge direction. It is connected. The peripheral end of the linear heat generation resistance element 22A3c is connected to the end of the arcuate heat generation resistance element 22A2c extending clockwise from 0 o'clock to 4 o'clock on the 0 o'clock side. ing. The 4 o'clock side end of the arc-shaped heat generation resistance element 22A2c is connected to the central end of the linear heat generation resistance element 22A3d extending in a short linear direction from this end toward the peripheral edge in the 4 o'clock direction. Has been done. The peripheral end of the linear heat generation resistance element 22A3d is connected to the 4 o'clock end of the arcuate heat generation resistance element 22A2d extending counterclockwise in an arc shape from 4 o'clock to 0 o'clock. There is.

The end portion of the arc-shaped heat generation resistance element 22A2d on the 0 o'clock side extends linearly from this end portion toward the central portion in the 0 o'clock direction, and is the end portion on the peripheral edge side of the linear heat generation resistance element 22A1. It is connected to the. Then, the end portion of the linear heat generation resistance element 22A1 on the central portion side is connected to the end portion of the linear communication heat generation resistance element 22A4 on the 2 o'clock side extending in a short linear direction from this end portion in the direction of 8 o'clock. Has been done. The linear communication heat generation resistance element 22A4 extends linearly from this end portion to the end portion B2 of the heat generation resistance element group 22B.

The heat generation resistance element group 22B exists in the fan-shaped region from 8:00 to 12:00. In the heat generation resistance element group 22B, one linear heat generation resistance element 22B1, four arcuate heat generation resistance elements 22B2a to 21B2d, four linear heat generation resistance elements 22B3a to 22B3d, and one linear communication heat generation resistance element 22B4 are connected in series. It is configured by being connected to.

The heat generation resistance element group 22C exists in the fan-shaped region from 4 o'clock to 8 o'clock. In the heat generation resistance element group 22C, one linear heat generation resistance element 22C1, four arcuate heat generation resistance elements 22C2a to 21C2d, four linear heat generation resistance elements 22C3a to 22C3d, and one linear communication heat generation resistance element 22C4 are connected in series. It is configured by being connected to.

Since the specific configuration of the heat generation resistance element groups 22B and 22C is the same as that of the heat generation resistance element group 22A, the description thereof will be omitted.

The upper heat-generating resistor 22 is preferably located inside the arc-shaped heat-generating resistance element constituting the lower heat-generating resistor 21 as the outer edge of the region is shown by a two-dot chain line in FIG. 2A.

The equivalent circuit diagram of the heat generating resistor 20 configured in this way is schematically shown as shown in FIG. As can be seen from FIG. 3, in the heat generating resistor 20, the central portion O is grounded, and the Y (star) connection consisting of the heat generating resistance element groups 21A, 21B, 21C, 22A, 22B, 22C of 6 zones is formed. It is a structure.

Then, the power supply terminal 40 directly connected to the ends A1 and A2, the power supply terminal 40 directly connected to the ends B1 and B2, and the power supply terminal 40 directly connected to the ends C1 and C2. The power supply terminals of the AC three-phase power supply are connected to the total of three power supply terminals 40 via the conductor and the power supply member. As a result, by using a power adjusting means such as a three-phase power regulator (three-phase thyristor), the current flowing through each heat generation resistance element group 21A, 21B, 21C, 22A, 22B, 22C is controlled so as to be separate. It becomes possible to do. Of the three heat generation resistance element groups 22A, 22B, and 22C, for example, the heat generation resistance element group 22A corresponds to the "first heat generation resistance element group", and the heat generation resistance element group 22B corresponds to the "second heat generation resistance element group". However, the heat generation resistance element group 22C corresponds to the "third heat generation resistance element group".

As a result, the number of power supply terminals 40 is as small as three with respect to the heat generation resistance element groups 21A, 21B, 21C, 22A, 22B, 22C consisting of six zones, and it is possible to reduce the inner diameter of the shaft 30. .. The 21A, 21B, and 21C may be provided with a common ground terminal. In this case, the number of power supply terminals is four, which is still less than or equal to the number of zones.

[Second Embodiment]
Next, the ceramic heater 200 according to the second embodiment of the present invention will be described mainly with reference to FIGS. 4 and 5. Since the ceramic heater 200 is similar to the ceramic heater 100 described above, only the differences will be described.

With reference to FIG. 1, the ceramic heater 200 is embedded in a base 10 made of a substantially disk-shaped insulator for sucking and holding a wafer (board) (not shown) so as not to be short-circuited with each other. It includes a heat generating resistor 120 and a hollow shaft 130 connected to a central portion of the lower surface of the substrate 10.

Further, the ceramic heater 200 includes three power supply terminals 40 for supplying electric power to the heat generating resistor 120.

An example of the pattern of the heat generating resistor 120 will be described with reference to FIG.

Here, in the heat generation resistor 120, three heat generation resistance element groups 121A, 121B, 121C in which one end portion X, Y, Z is located near the central portion O, respectively, and one end portion is located in the central portion O, respectively. Three heat resistance element groups 122A, 122B, which are located and whose other end is directly connected to the other end, which is different from the ends X, Y, Z of the heat generation resistance element groups 121A, 121B, 121C, respectively. It is composed of 122C.

As shown in FIG. 4, the heat generation resistance element group 121A has a direction in which the linear heat generation resistance element 121A1 extending linearly from one end Y extends toward the peripheral edge side as the direction at 0 o'clock, and is 4 from 0 o'clock. It exists on the veranda of the fan-shaped region of time. The heat generation resistance element group 121A is configured by connecting one linear heat generation resistance element 121A1, three arcuate heat generation resistance elements 121A2a to 121A2c, and two linear heat generation resistance elements 121A3a, 121A3b in series. ..

Specifically, the linear heat generation resistance element 121A1 extends linearly from the end portion Y located slightly away from the central portion O in the 0 o'clock direction to the peripheral portion in the 0 o'clock direction. The end of the linear heat generation resistance element 121A1 on the peripheral edge side opposite to the end Y is an arcuate heat generation resistance element 121A2a extending clockwise from this end in the direction of 0 o'clock to 4 o'clock. It is connected to the end on the 0 o'clock side of. The end of the arc-shaped heat-generating resistance element 121A2a on the 4 o'clock side is a linear end of the linear heat-generating resistance element 121A3a extending in a short linear direction from this end in the direction of 10 o'clock in the central O direction. It is connected. The end of the linear heat generation resistance element 121A3a on the central portion O side extends counterclockwise from this end in an arc shape extending from 4 o'clock to 0 o'clock at 4 o'clock of the arcuate heat generation resistance element 121A2b. It is connected to the end on the side.

The end portion of the arc-shaped heat generation resistance element 121A2b on the 0 o'clock side extends from this end portion in a short linear shape in the direction of 6 o'clock in the central O direction, and is the end portion on the peripheral side of the linear heat generation resistance element 121A3b. Is connected. The end of the linear heat generation resistance element 121A3b on the O side at the center is the end of the arcuate heat generation resistance element 121A2c extending clockwise from this end in the direction of 0 o'clock to 4 o'clock on the 0 o'clock side. It is connected to the end of. The end portion of the arc-shaped heat generation resistance element 121A2c on the 4 o'clock side is connected to the middle portion of the linear heat generation resistance element 121C1 of the heat generation resistance element group 121C.

The heat generation resistance element group 121B exists on the peripheral side of the fan-shaped region from 8:00 to 12:00. The heat generation resistance element group 121B is configured by connecting one linear heat generation resistance element 121B1, three arcuate heat generation resistance elements 121B2a to 121B2c, and two linear heat generation resistance elements 121B3a and 121B3b in series. ..

The heat generation resistance element group 121C exists on the peripheral side of the fan-shaped region from 4 o'clock to 8 o'clock. The heat generation resistance element group 121C is configured by connecting one linear heat generation resistance element 121C1, three arcuate heat generation resistance elements 121C2a to 121C2c, and two linear heat generation resistance elements 121C3a and 121C3b in series. ..

Since the specific configuration of the heat generation resistance element groups 121B and 121C is the same as that of the heat generation resistance element group 121A, the description thereof will be omitted.

The heat generation resistance element group 122A exists on the inner peripheral side portion of the fan-shaped region from 0:00 to 4:00. The heat generation resistance element group 122A is composed of four arcuate heat generation resistance elements 122A1a to 122A1d, three linear heat generation resistance elements 122A2a to 122A2c, and one linear central heat generation resistance element 122A3 connected in series. There is.

Specifically, the arc-shaped heat-generating resistance element 122A1a extends in an arc shape from 4 o'clock to 0 o'clock counterclockwise from the intermediate portion L of the linear heat-generating resistance element 121C1. The end of the arcuate heat generation resistance element 122A1a on the 0 o'clock side is on the peripheral edge side of the linear heat generation resistance element 122A2a extending in a short linear shape in the 0 o'clock direction from this end toward the central O side. It is connected to the end. The end of the linear heat generation resistance element 122A2a on the central portion O side is located on the 6 o'clock side of the arcuate heat generation resistance element 122A1b extending clockwise from this end in an arc shape from 0 o'clock to 4 o'clock. It is connected to the end.

The end portion of the arc-shaped heat generation resistance element 122A1b on the 4 o'clock side is a peripheral end portion of the linear heat generation resistance element 122A2b extending in a short linear shape in the 4 o'clock direction from this end portion toward the central portion O side. It is connected to the. The end of the linear heat generation resistance element 122A2b on the O side at the center is the 10 o'clock side of the arcuate heat generation resistance element 122A1c extending in an arc shape from 4 o'clock to 0 o'clock counterclockwise from this end. It is connected to the end of.

The end portion of the arc-shaped heat generation resistance element 122A1c on the 0 o'clock side is a peripheral end portion of the linear heat generation resistance element 122A2c extending in a short linear shape in the 0 o'clock direction from this end portion toward the central portion O side. It is connected to the. The end of the linear heat generation resistance element 122A2c on the O side of the central portion is an arcuate heat generation resistance element 1 extending clockwise from this end in an arc shape from 0 o'clock to 2 o'clock.
It is connected to the end of 22A1d on the 0 o'clock side. The 2 o'clock side end of the arc-shaped heat generation resistance element 122A2d is connected to the peripheral end of the linear central heat generation resistance element 122A3 extending in a short straight line from this end to the center O in the 8 o'clock direction. Has been done.

The heat generation resistance element group 122B exists on the inner peripheral side portion of the fan-shaped region from 8:00 to 12:00. The heat generation resistance element group 122B is configured by connecting four arc-shaped heat generation resistance elements 122B1a to 122B1d, three linear heat generation resistance elements 122B2a to 122B2c, and one linear central heat generation resistance element 122B3 in series. Has been done.

The heat generation resistance element group 122C exists on the inner peripheral side portion of the fan-shaped region from 4 o'clock to 8 o'clock. The heat generation resistance element group 122C is composed of four arcuate heat generation resistance elements 122C1a to 122C1d, three linear heat generation resistance elements 122C2a to 122C2c, and one linear central heat generation resistance element 122C3 connected in series. There is.

Since the specific configuration of the heat generation resistance element groups 122B and 122C is the same as that of the heat generation resistance element group 122A, the description thereof will be omitted.

The equivalent circuit diagram of the heat generating resistor 120 configured in this way is schematically shown as shown in FIG. As can be seen from FIG. 5, in the heat generating resistor 120, the central portion O is grounded (earth), and the Y (star) connection consisting of the heat generating resistance element groups 121A, 121B, 121C, 122A, 122B, 122C of 6 zones is formed. It is a structure.

Then, the power supply terminals of the AC three-phase power supply are connected to the total of three power supply terminals 40 directly connected to the ends X, Y, and Z via the conductor and the power supply member. As a result, by using a power adjusting means such as a three-phase power regulator (three-phase thyristor), the current flowing through each heat generation resistance element group 121A, 121B, 121C, 122A, 122B, 122C is controlled so as to be separate. It becomes possible to do. Of the three heat generation resistance element groups 121A, 121B, 121C, for example, the heat generation resistance element group 121A corresponds to the "first heat generation resistance element group", and the heat generation resistance element group 121B corresponds to the "second heat generation resistance element group". However, the heat generation resistance element group 121C corresponds to the "third heat generation resistance element group".

As a result, the number of power supply terminals 40 is as small as three with respect to the heat generation resistance element groups 121A, 121B, 121C, 122A, 122B, 122C in the six zones, and the inner diameter of the shaft 30 can be reduced.

A ground terminal common to the heat generation resistance element groups 122A, 122B, and 122C may be provided. In this case, the number of power supply terminals is four, which is still less than or equal to the number of zones.

As can be understood from FIG. 5, for example, the heat generation resistance element groups 121A, 121C, 122A are preferably connected at one point of the end portion X. However, as can be understood from FIG. 4, the heat generation resistance element groups 121A and 121C are in the middle part of the linear heat generation resistance element 121C1, and the heat generation resistance element groups 121A and 122A are in the middle part L of the linear heat generation resistance element 121C1. They are connected to each other and share a part of the linear heat generation resistance element 121C1. Therefore, it is preferable that the resistance value of the portion from the end portion X to the intermediate portion L and the portion up to the intersection with the heat generation resistance element group 121A is as small as possible. The same applies to the portion from the end portion Y to the intermediate portion M, the portion up to the intersection with the heat generation resistance element group 1 21B, the portion from the end portion Z to the intermediate portion N, and the portion up to the intersection with the heat generation resistance element group 121C. ..

As described above, the present embodiment is characterized in that all the heat generating resistors 120 can be arranged in the same plane in the substrate 10.

[Third Embodiment]
Next, the ceramic heater 300 according to the third embodiment of the present invention will be described with reference to FIGS. 6 to 8.

With reference to FIG. 1, the ceramic heater 300 includes a substrate 10 made of a substantially disk-shaped insulator for adsorbing and holding a wafer (substrate) (not shown), a heat generating resistor 220 embedded in the substrate 10, and a heat generating resistor 220. It includes a hollow shaft 30 connected to the center of the lower surface of the substrate 10.

Further, the ceramic heater 300 includes a plurality of power supply terminals 40 for supplying electric power to the heat generating resistor 220.

An example of the pattern of the heat generating resistor 220 will be described with reference to FIGS. 6, 7A and 7B.

The heating resistor 220 includes a lower heating resistor 221 and an upper heating resistor 222 arranged above the lower heating resistor 221 and an upper heating resistor 222 arranged above the middle heating resistor 222. It consists of 223.

Here, the lower heat-generating resistor 221 is composed of four heat-generating resistance element groups 221A, 221B, 221C, and 221D that are directly connected to the ends A1, B1, C1, and D1, respectively.

As shown in FIG. 6A, the heat generation resistance element group 221A has a linear heat generation resistance element 221A1 extending linearly from one end A1 located near the center toward the peripheral edge side at 0 o'clock. It exists on the peripheral side of the fan-shaped region at 3 o'clock. The heat generation resistance element group 221A is configured by connecting one linear heat generation resistance element 221A1, three arcuate heat generation resistance elements 221A2a to 221A2c, and two linear heat generation resistance elements 221A3a, 221A3b in series. ..

Specifically, the linear heat generation resistance element 221A1 extends in a long linear shape from the end portion A1 toward the peripheral edge side in the 0 o'clock direction. An end portion on the 0 o'clock side of the arcuate heat generation resistance element 221A2a extending clockwise from 0 o'clock to 3 o'clock in an arc shape is connected to the intermediate portion P of the linear heat generation resistance element 221A1. There is. The end portion of the arc-shaped heat generation resistance element 221A2c on the 3 o'clock side is the end portion on the central portion side of the linear heat generation resistance element 221A3b extending in a short linear direction from this end portion toward the peripheral edge side in the 3 o'clock direction. Is connected. The peripheral end of the short linear heat generation resistance element 221A3b extends counterclockwise from this end in an arc shape from 3 o'clock to 0 o'clock, and the end on the 3 o'clock side of the arcuate heat generation resistance element 221A2b. It is connected to the part.

The end portion of the arc-shaped heat generation resistance element 221A2b on the 0 o'clock side is the end portion on the central portion side of the linear heat generation resistance element 221A3a extending in a short straight line from this end portion toward the peripheral edge side in the direction of 0 o'clock. Is connected. The peripheral end of the linear heat generation resistance element 221A3a extends clockwise from this end in an arc shape from 0 o'clock to 3 o'clock to the end of the arcuate heat generation resistance element 221A2a on the 0 o'clock side. It is connected. The end portion of the arc-shaped heat generation resistance element 221A2a on the 3 o'clock side is connected to the peripheral end portion of the linear heat generation resistance element 221D1 of the heat generation resistance element group 221D.

The heat generation resistance element group 221B exists on the peripheral side of the fan-shaped region from 9:00 to 12:00. The heat generation resistance element group 221B is configured by connecting one linear heat generation resistance element 221B1, three arcuate heat generation resistance elements 221B2a to 221B2c, and two linear heat generation resistance elements 221B3a and 221B3b in series. ..

The heat generation resistance element group 221C exists on the peripheral side of the fan-shaped region from 6 o'clock to 9 o'clock. The heat generation resistance element group 221C is configured by connecting one linear heat generation resistance element 221C1, three arcuate heat generation resistance elements 221C2a to 221C2c, and two linear heat generation resistance elements 221C3a and 221C3b in series. ..

The heat generation resistance element group 221D exists on the peripheral side of the fan-shaped region from 3 o'clock to 6 o'clock. The heat generation resistance element group 221D is configured by connecting one linear heat generation resistance element 221D1, three arcuate heat generation resistance elements 221D2a to 221D2c, and two linear heat generation resistance elements 221D3a and 221D3b in series. ..

Since the specific configuration of the heat generation resistance element groups 221B to 221D is the same as that of the heat generation resistance element group 221A, the description thereof will be omitted.

The middle heat-generating resistor 222 is one heat-generating resistance element group 222 that is located directly above the ends A1 and C1 and has ends A2 and C2 that are directly connected to the ends A1 and C1 as both ends. It is composed of.

The heat generation resistance element group 222 exists in the annular region as shown in FIG. 7A. The heat generation resistance element group 222 includes a first heat generation resistance element group 222A composed of three linear heat generation resistance elements 222A1a to 222A1c, two semi-arc-shaped heat generation resistance elements 222A2b and 222A2c, and three linear heat generation resistance elements 222B1a to 222B1c. The second heat generation resistance element group 222B composed of two semi-arc-shaped heat generation resistance elements 222B2b and 222B2c and one annular heat generation resistance element 222C are connected to each other.

The first heat generation resistance element group 222A is a semicircle on the left half, with the direction in which the linear heat generation resistance element 222A1c extends linearly from one end A2 located near the central portion toward the peripheral edge side as the 0 o'clock direction. It exists on the peripheral side of the fan-shaped region.

Specifically, the linear heat generation resistance element 222A1c extends in a long linear shape from the end portion A2 toward the peripheral edge side in the 0 o'clock direction. The peripheral end of the linear heat generation resistance element 222A1c extends counterclockwise from this end in a semicircular shape from 0 o'clock to 6 o'clock, and the end of the semicircular heat generation resistance element 222A2c on the 0 o'clock side. Is connected. The end of the semicircular heat-generating resistance element 222A2c on the 6 o'clock side is the end of the linear heat-generating resistance element 222A1b on the central portion side extending in a short straight line from this end toward the peripheral edge in the direction of 6 o'clock. The parts are connected. The peripheral end of the linear heat generation resistance element 222A1b extends clockwise from this end in a semicircular shape from 6 o'clock to 12 o'clock on the 6 o'clock side of the semicircular heat generation resistance element 222A2b. It is connected to the end. The 12 o'clock side end of the semicircular heat generation resistance element 222A2b is a central end of the linear heat generation resistance element 222A1a extending in a short straight line from this end toward the peripheral edge in the 12 o'clock direction. The parts are connected. The linear heat generation resistance element 222A1a extends from this end portion toward the peripheral edge side in a short linear shape in the 0 o'clock direction, and the peripheral edge side end portion is the annular heat generation resistance element 222C in the 0 o'clock direction. It is connected to the middle part.

Since the specific configuration of the second heat generation resistance element group 222B is the same as that of the first heat generation resistance element group 222A, the description thereof will be omitted.

The middle heat-generating resistor 222 is preferably located inside the arc-shaped heat-generating resistance element constituting the lower heat-generating resistor 221 as the outer edge of the region is shown by a two-dot chain line in FIG.

The lower heat-generating resistor 223 is located directly above the ends B1 and D1, and has one heat-generating resistance element group 223 having ends B2 and D2 directly connected to the ends B1 and D1 as both ends. It is composed of.

The heat generation resistance element group 223 exists in the annular region as shown in FIG. 7B. The heat generation resistance element group 223 is configured by connecting two linear heat generation resistance elements 223A1a and 223A1b and one annular heat generation resistance element 223A2.

Specifically, the heat generation resistance element group 223 linearly generates heat with the direction in which the linear heat generation resistance element 223A1a extends linearly from one end B2 located near the center toward the peripheral edge side at 9 o'clock. An annular heat generating resistance element 222A2 at 9 o'clock is connected to an end portion on the peripheral edge side of the resistance element 223A1a. An intermediate portion of the annular heat generation resistance element 223A2 on the 3 o'clock side is connected to an end portion on the peripheral edge side of the linear heat generation resistance element 223A1b extending in a short linear shape in the 9 o'clock direction from this portion. Then, the linear heat generation resistance element 223A1b extends toward the central portion side to the end portion D2.

The upper heat-generating resistor 223 is preferably located inside the arc-shaped heat-generating resistance element constituting the middle-side heat-generating resistor 222, as the outer edge of the region is shown by a two-dot chain line in FIG. 7A.

The equivalent circuit diagram of the heat generating resistor 220 configured in this way is schematically shown as shown in FIG. As can be seen from FIG. 8, the heat generation resistor 220 is a connection structure composed of heat generation resistance element groups 221A, 221B, 221C, 221D, 222, 223 in 6 zones. Of the four heat generation resistance element groups 221A, 221B, 221C and 221D, for example, the heat generation resistance element group 221A corresponds to the "first heat generation resistance element group", and the heat generation resistance element group 221B is the "second heat generation resistance element group". The heat generation resistance element group 221C corresponds to the "third heat generation resistance element group", and the heat generation resistance element group 221D corresponds to the "fourth heat generation resistance element group". Further, the heat generation resistance element group 222 corresponds to the "fifth heat generation resistance element group", and the heat generation resistance element group 223 corresponds to the "sixth heat generation resistance element group".

Then, for example, the power supply terminal 40 directly connected to the ends A1 and A2, the power supply terminal 40 directly connected to the ends B1 and B2, and the power supply terminal directly connected to the ends D1 and D2. The power supply terminals of the AC three-phase power supply are connected to the total of three power supply terminals 40 of 40 via the conductor and the power supply member. Thereby, by using a power adjusting means such as a three-phase power regulator (three-phase thyristor), the currents flowing through the heat generating resistance elements 221A, 221B, 221C, 221D, 222, 223 are controlled to be separate. It becomes possible.

As a result, the number of power supply terminals 40 is as small as three with respect to the heat generation resistance element groups 221A, 221B, 221C, 221D, 222, 223 in the six zones, and the inner diameter of the shaft 30 can be reduced.

As can be understood from FIG. 8, for example, the heat generation resistance element groups 221A, 221B, and 222 are preferably connected at one point of the end portion A1 (= A2). However, as can be understood from FIG. 6, the heat generation resistance element groups 221A and 221B are connected by an intermediate portion P of the linear heat generation resistance element 221A1 and share a part of the linear heat generation resistance element 221A1. Therefore, it is preferable that the resistance value of the portion from the end portion A1 to the intermediate portion P is as small as possible. The same applies to each portion from the end portion B1 to the intermediate portion Q, from the end portion C1 to the intermediate portion R, and from the end portion D1 to the intermediate portion S.

The embodiments of the present invention have been described above, but the present invention is not limited thereto. For example, the configuration, shape, number, etc. of the heat generation resistance element groups constituting each heat generation resistor are not limited to those described above, and further, the configuration, shape, number, and connection of the heat generation resistance elements constituting each heat generation resistance element group are not limited to those described above. The position and the like are not limited to those described above.

For example, the heat generation resistance element group of the heat generation resistor is configured so as to have the schematic equivalent circuit diagram shown in FIG. 11 such that three schematic equivalent circuit diagrams of the heat generation resistor 20 shown in FIG. 3 are connected. May be good.

Hereinafter, the present invention will be described with reference to specific examples of the present invention.

(Example)
In the example, a ceramic heater 100 was obtained using a substrate 10 made of aluminum nitride added with yttrium oxide in which a heat generating resistor 20 made of metal was embedded.

[Manufacturing of ceramic heater]
A powder mixture composed of 97% by mass of aluminum nitride powder and 3% by mass of yttrium oxide powder was obtained, filled in a mold, and subjected to uniaxial pressure treatment. As a result, a first layer having a diameter of 340 mm and a thickness of 10 mm was formed.

Next, a molybdenum mesh (wire diameter 0.1 mm, opening 50 mesh) having a diameter of 290 mm, which serves as the electrode 20 having the shape shown in FIG. 4, was placed on the first layer. Subsequently, the powder mixture formed earlier was filled on the heat generating resistor 20 to a predetermined thickness to form a second layer. Then, hot press firing was performed at a pressure of 10 MPa at a firing temperature of 1800 ° C. and a firing time of 2 hours to obtain a ceramic sintered body having a diameter of 340 mm and a thickness of 20 mm.

After that, the entire surface was ground and polished to have a surface roughness of Ra 0.4 μm and a flatness of 0.9 μm.

Then, the upper end surface of a cylindrical shaft 30 having a thermal conductivity of 80 kW / (m · k) at room temperature and having a length of 200 mm was bonded to the lower surface of the substrate 10 by a diffusion bonding method. The dimensions of the cylindrical portion 31 of the shaft 30 were an inner diameter of 34.14 mm and an outer diameter of 40.14 mm. The outer diameter of the enlarged diameter portion 32 of the shaft 30 was made 20 mm larger than the outer diameter of the cylindrical portion 31.

The number of terminals 40 was four, and they were arranged as shown in FIG. 9A. The terminal 40 was formed by drilling a hole having a diameter of 8 mm from the back surface of the substrate 10 to the heat generating resistor 20, and silver brazing a cylindrical nickel feeding terminal having a diameter of 8 mm to the exposed heat generating resistor 20.

In this way, the ceramic heater 100 was obtained.

[Evaluation results]
A blackened dummy wafer was placed on the wafer mounting surface of the ceramic heater 100, electric power was supplied to the terminal 40 to raise the temperature of the ceramic heater 100, and the temperature of the dummy wafer surface was measured with an IR camera. The temperature distribution of the dummy wafer was measured 15 minutes after the surface temperature of the dummy wafer reached approximately 500 ° C.

At this time, the voltage of the waveform shown in FIG. 10A was supplied between the terminals between OXs, shown in FIG. 10B between the terminals between OYs, and the waveform shown in FIG. 10C was supplied between the terminals between OZs. The voltage was changed every 20 ms to obtain a waveform with a period of 80 ms. The wave height was appropriately adjusted so that the temperature distribution was uniform. The power supply is not limited to this, and a known phase control method or cycle control (zero cross control) method can be applied. It can also be applied to both alternating current and direct current.

The average temperature of the central region (region within 20 mm in diameter) as the central temperature was compared with the average temperature of the region within 20 mm in diameter centered on the position with a radius of 120 mm in the direction of 3 o'clock as the ambient temperature.

The result was a central temperature of 502 ° C and an ambient temperature of 505 ° C. From this, it was found that the soaking property of the ceramic heater 100 was good.

(Comparison example)
Seven terminals 40 were arranged as shown in FIG. 9B. This is because six terminals 40 corresponding to the electrodes of the six zones and one terminal 40 corresponding to the common electrode are required, for a total of seven terminals 40.

Due to the large number of terminals 40, the shape of the shaft 30 is that the inner diameter of the cylindrical portion 31 is 48.14 mm and the outer diameter is 54.14 mm.

[Evaluation results]
The temperature evaluation method was the same as in the examples. The results were a central temperature of 498 ° C. and an ambient temperature of 505 ° C., and the difference was large as compared with the examples.

Comparing the examples and the comparative examples, it is considered that when the number of terminals is large, the heat escape due to the increase in the cross-sectional area of the shaft is large and the temperature distribution on the heater surface is deteriorated.

Then, it was confirmed that if the number of terminals is reduced as in the present invention, the ceramic heater 100 with less heat escape can be obtained even if the number of zones is increased or the shaft 30 is provided.

According to the present invention, it is possible to suppress an increase in the number of power feeding terminals 40 as compared with an increase in the number of zones of the heat generating resistor 20, and it is possible to reduce the diameter of the shaft 30 at the same time. It can also have the effect of suppressing heat escape from 30 and further leveling the temperature.

10 ... Substrate (ceramics substrate), 20, 120, 220 ... Heat generation resistor, 21 ... Lower heat generation resistor, 22 ... Upper heat generation resistor, 21A, 21B, 21C, 22A, 22B, 22C ... Heat generation resistance element group, 30 ... Shaft (support member), 31 ... Cylindrical part, 32 ... Diameter expansion part, 40 ... Power supply terminal, 100, 200, 300 ... Ceramic heater, 120A, 120B, 120C, 120D, 120E, 120F ... Heat generation resistance element group, 221 ... Lower heat-generating resistor, 221A, 221B, 221C, 221D ... Heat-generating resistance element group, 222 ... Middle-side heat-generating resistor, 222A, 222B ... Heat-generating resistance element group, 223 ... Upper heat-generating resistor, heat-generating resistance element group, A1, A2, B1, B2, C1, C2, D1, D2 ... end, O ... center (end), X, Y, Z ... end.

Claims (7)

A cylindrical support made of ceramics, a ceramic substrate on which an object to be heated is placed, a heat generating resistor built in the ceramic substrate, and ceramics, which is connected to the center of the lower surface of the ceramic substrate. A ceramic heater equipped with a member
The heat generation resistor is composed of three or more heat generation resistance element groups, each of which is composed of one or more heat generation resistance elements.
At least three of the three or more heat generation resistance element groups have direct ends at both ends of the other one of the at least three heat generation resistance element groups. A ceramic heater, characterized in that at least power feeding terminals for supplying electric power are connected to a total of three ends including both ends. The at least three heat generation resistance element groups are three heat generation resistance element groups, and each of the three heat generation resistance element groups has the heat generation resistance of one of the three heat generation resistance element groups at both ends thereof. The ends of the element group are directly connected, and the total of three ends including the both ends are grounded via the heat generation resistance element group different from the three heat generation resistance element groups. The ceramics heater according to claim 1, wherein the ceramic heater is characterized. The at least three heat generation resistance element groups are four heat generation resistance element groups, and each of the four heat generation resistance element groups has the heat generation resistance of one of the four heat generation resistance element groups at both ends. The ends of the element group are directly connected, and each of the both ends is connected to the end of another heat resistance element group different from the four heat generation resistance element groups connected to the both ends. The ceramics heater according to claim 1, wherein the ceramic heater is provided. A ceramic substrate made of ceramics on which an object to be heated is placed on the upper surface,
The heat-generating resistor built in the ceramic substrate and
A ceramic heater made of ceramics and provided with a tubular support member connected to the center of the lower surface of the ceramic substrate.
The heat generating resistor is
It is composed of three or more heat generation resistance element groups including a first heat generation resistance element group, a second heat generation resistance element group, and a third heat generation resistance element group.
Each of the three or more heat generation resistance element groups is composed of one or more heat generation resistance elements.
Each of the three or more heat generation resistance element groups has one end and the other end.
A first end portion in which one end of the first heat generation resistance element group is connected to one end of the second heat generation resistance element group, and
A second end portion in which the other end of the second heat generation resistance element group is connected to one end of the third heat generation resistance element group, and
A third end portion in which the other end portion of the third heat generation resistance element group is connected to the other end portion of the first heat generation resistance element group, and
A first power supply terminal connected to the first end and supplying power to the first end,
A second power supply terminal that is connected to the second end and supplies power to the second end.
A third power supply terminal connected to the third end and supplying power to the third end,
A ceramic heater characterized by having. The three ends including the first end portion, the second end portion, and the third end portion are the first heat generation resistance element group, the second heat generation resistance element group, and the third heat generation resistance, respectively. The ceramics heater according to claim 4, wherein the heat generating resistance element group different from the element group is grounded. A ceramic substrate made of ceramics on which an object to be heated is placed on the upper surface,
The heat-generating resistor built in the ceramic substrate and
A ceramic heater made of ceramics and provided with a tubular support member connected to the center of the lower surface of the ceramic substrate.
The heat generating resistor is
It consists of four or more heat generation resistance element groups including the first heat generation resistance element group, the second heat generation resistance element group, the third heat generation resistance element group, and the fourth heat generation resistance element group.
Each of the four or more heat generation resistance element groups is composed of one or more heat generation resistance elements.
Each of the four or more heat generation resistance element groups has one end and the other end.
A first end portion in which one end portion of the first heat generation resistance element group is connected to one end portion of the second resistance element group, and
A second end portion in which the other end of the second heat generation resistance element group is connected to one end of the third heat generation resistance element group, and
A third end portion in which the other end of the third heat generation resistance element group is connected to one end of the fourth heat generation resistance element group, and
A fourth end portion in which the other end portion of the fourth heat generation resistance element group is connected to the other end portion of the first resistance element group, and
A first power supply terminal connected to the first end and supplying power to the first end,
A second power supply terminal that is connected to the second end and supplies power to the second end.
A third power supply terminal connected to the third end and supplying power to the third end,
A fourth power supply terminal that is connected to the fourth end and supplies power to the fourth end.
A ceramic heater characterized by having. The area between the first end and the third end is different from the first heat generation resistance element group, the second heat generation resistance element group, the third heat generation resistance element group, and the fourth heat generation resistance element group. It is connected via the fifth heat generation resistance element group, which is the heat generation resistance element group, and is connected.
Between the second end and the fourth end are the first heat generation resistance element group, the second heat generation resistance element group, the third heat generation resistance element group, the fourth heat generation resistance element group, and the second. 5. The ceramic heater according to claim 6, wherein the ceramic heater is connected via a sixth heat generation resistance element group, which is a heat generation resistance element group different from the heat generation resistance element group.

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