STRUCTURE AND HEATING DEVICE

Structures (2, 2A to 2P) according to the present disclosure have respective bases (10, 10A), electrode layers, and terminals. The bases (10, 10A) are made of a ceramic. The electrode layers (111, 111C, 111D, 111F, 111M, 111N, 111O) are located inside the respective bases (10, 10A). The terminals (41, 41G, 41H, 41I, 41J, 41K, 41L) are electrically connected to the respective electrode layers (111, 111C, 111D, 111F, 111M, 111N, 111O) at respective tip portions of the terminals. Further, the terminals (41, 41G, 41H, 41I, 41J, 41K, 41L) are in contact with the respective electrode layers (111, 111C, 111D, 111F, 111M, 111N, 111O) at respective tip surfaces and side surfaces of the terminals.

TECHNICAL FIELD

The present disclosure relates to a structure and a heating device.

BACKGROUND ART

Substrates made of ceramics have superior heat resistance compared to metals and resins. For example, aluminum nitride-based ceramics have a high thermal conductivity, and thus may be used as a structure for placing or holding workpieces such as various elements and components during thermal treatment of the workpieces.

When a structure is used as a heater for thermal treatment of a workpiece, a power supply terminal is connected to an electrode layer in order to connect the electrode layer embedded inside the structure to a power supply.

CITATION LIST

Patent Literature

Patent Document 1: JP 2003-40686 A

SUMMARY OF INVENTION

A structure according to one aspect of the present disclosure includes a base, an electrode layer, and a terminal. The base is made of a ceramic. The electrode layer is located inside the base. The terminal is electrically connected to the electrode layer at a tip portion of the terminal. In addition, the terminal is in contact with the electrode layer at a tip surface and a side surface of the terminal.

DESCRIPTION OF EMBODIMENTS

Embodiments of a structure and a heating device according to the present disclosure (hereinafter, referred to as “embodiments”) will be described in detail below with reference to the accompanying drawings. Note that the embodiments described below are not intended to limit the structure and the heating device according to the present disclosure. Each of the embodiments can be appropriately combined within a range in which the processing contents do not contradict each other. In each of the embodiments below, the same reference numerals are assigned to the same portions, and redundant descriptions thereof will be omitted.

In the embodiments described below, expressions such as “constant”, “orthogonal”, “vertical,” and “parallel” may be used, but these expressions do not need to be exactly “constant”, “orthogonal”, “vertical,” and “parallel”. In other words, each of the above-described expressions allows for deviations in, for example, manufacturing accuracy, positioning accuracy, and the like.

Further, in each of the drawings referred to below, for ease of explanation, the vertical upward direction is defined as a Z axis direction.

Overall Configuration of Wafer Placement Device

First, a configuration of a wafer placement device according to an embodiment will be described with reference toFIG.1.FIG.1is a schematic perspective view illustrating a wafer placement device1according to the embodiment.

The wafer placement device1according to the embodiment illustrated inFIG.1is a device for placing a semiconductor wafer, a crystal wafer, or another wafer (hereinafter, simply referred to as “wafer”). The wafer placement device1has a heating function for heating the placed wafer, and is mounted on, for example, a substrate processing device that performs plasma treatment or the like on the wafer.

As illustrated inFIG.1, the wafer placement device1includes a structure2, a wiring portion4, an electric power supply unit5, and a controller6.

The structure2includes a base10that is disc-shaped and has a thickness in an up-down (Z axis) direction, and a cylindrical shaft20connected to the base10. The wafer is placed on an upper surface101of the base10. Further, the shaft20is connected to a lower surface102of the base10. The upper surface101and the lower surface102of the base10have substantially the same shape, and both have a larger diameter than the wafer. An electrode layer (not illustrated here) as a heating element is located inside the base10.

The wiring portion4electrically connects the electrode layer located inside the base10to the electric power supply unit5located outside the base10. The electric power supply unit5is electrically connected to the electrode layer via the wiring portion4, and supplies electric power to the electrode layer via the wiring portion4. The electric power supply unit5includes a power supply circuit that converts electric power supplied from a power supply (not illustrated) to an appropriate voltage. The controller6controls the supply of electric power in the electric power supply unit5.

The wafer placement device1is configured as described above, and heats the wafer placed on the wafer placement surface101by generating heat in the electrode layer inside the base10using the electric power supplied from the electric power supply unit5.

Configuration of Structure

Next, a configuration of the structure2will be described with reference toFIG.2.FIG.2is a schematic cross-sectional view of the structure2according to the embodiment. Note thatFIG.2illustrates a schematic cross-sectional view taken along a line II-II illustrated inFIG.1.

As illustrated inFIG.2, an electrode layer11is located inside the base10. In the present embodiment, the electrode layer11includes a first electrode layer111and a second electrode layer112. The first electrode layer111is an electrode layer located relative to the lower surface102side of the base10. The second electrode layer112is an electrode layer located relative to the upper surface101(hereinafter, may be referred to as “wafer placement surface101”) side of the base10in relation to the first electrode layer111. The first electrode layer111and the second electrode layer112are made of, for example, a metal such as Ni, W, Mo, or Pt, or an alloy containing at least one of the above metals.

The first electrode layer111and the second electrode layer112extend along the wafer placement surface101. Specifically, the first electrode layer111and the second electrode layer112are arranged over substantially the entire surface of the wafer placement surface101while drawing a predetermined pattern such as a spiral pattern or a meandering pattern. The thickness of the first electrode layer111and the second electrode layer112is, for example, 30 μm to 120 μm.

The first electrode layer111and the second electrode layer112are electrically connected to each other through a via conductor113. Note that the electrode layer11does not necessarily have to include two layers, but may include at least one layer (e.g., the first electrode layer111).

The base10is made of a ceramic. A main component of the ceramic constituting the base10is, for example, aluminum nitride (AlN), aluminum oxide (Al2O3, alumina), silicon carbide (SiC), or silicon nitride (Si3N4). The main component here is, for example, a material that occupies 50 mass % or more or 80 mass % or more of the material.

Note that in addition to the ceramic described above, the base10may contain, for example, a sintering aid. Examples of the sintering aid include a mixture of calcium oxide (CaO) and yttrium oxide (Y2O3).

The upper surface101(wafer placement surface101) and the lower surface102of the base10are parallel to each other. Further, the shape of the base10is not limited to any particular shape. For example, in the embodiment, the shape of the base10is a circular shape in a plan view, but the shape of the base10is not limited thereto, and may be an elliptical shape, a rectangular shape, a trapezoidal shape, or the like in a plan view. Dimensions of the base10, as an example, are 20 cm to 35 cm in diameter and 4 mm to 30 mm in thickness.

Shaft

The shaft20has a cylindrical shape, and an upper end thereof is bonded to a central portion of the lower surface of the base10. As one specific method, the shaft20is bonded (adhered) to the lower surface102of the base10by an adhesive. As another specific method, the shaft20may be bonded to the base10by solid-phase bonding. The shape of the shaft20is not limited to any particular shape. As one specific shape, the shaft20has a cylindrical shape. As another specific shape, the shaft20may have, for example, a square cylinder shape. The material of the shaft20is not limited to any particular material. As one specific material, the material of the shaft20is a ceramic having insulating properties. As another specific material, the material of the shaft20may be, for example, a conductive material (metal).

The cylindrical shaft20has an upper surface21that is bonded to the lower surface102of the base10, a lower surface22that is located opposite to the upper surface21, an inner surface23that connects the upper surface21and the lower surface22and constitutes an inner side of the shaft20, and an outer surface24that connects the upper surface21and the lower surface22and constitutes an outer side of the shaft20.

In the illustrated example, the inner surface23is provided parallel to the outer surface24along the direction in which the shaft20extends. In another perspective, the inner surface23is provided parallel to a straight line parallel to the thickness direction of the base10. However, the inner surface23may be inclined so that the inner diameter of the shaft20decreases downward, or may be inclined so that the inner diameter of the shaft20increases downward. Note that the outer surface24can be similarly configured. This allows the shaft20to be continuously different in at least one of the inner and outer diameters from the upper end to the lower end.

Wiring Portion

The wiring portion4includes a terminal41and lead wires42. The terminal41is a metal (bulk material) having some length in the up-down direction. An upper end portion of the terminal41is located inside the base10, and a lower end portion of the terminal41is located outside the base10. In the illustrated example, the terminal41is electrically connected to the first electrode layer111. The terminal41is also electrically connected to the second electrode layer112through the via conductor113. The shape of the terminal41is not limited to any particular shape. In one specific example, the terminal41has a cylindrical shape. The terminal41is made of, for example, a metal such as Ni, W, Mo, or Pt, or an alloy containing at least one of the above metals.

Internal Configuration of Base

Next, an internal configuration of the base10described above will be specifically described with reference toFIG.3.FIG.3is a schematic enlarged view of an H portion illustrated inFIG.2.

As illustrated inFIG.3, the terminal41is electrically connected to the electrode layer11(here, the first electrode layer111) at a tip portion410thereof. Specifically, the terminal41is in contact with the first electrode layer111at a tip surface411thereof and a side surface412thereof.

When a structure made of a ceramic is used as a heater for thermal treatment of a workpiece, a power supply terminal is connected to an electrode layer in order to connect the electrode layer embedded inside the structure with a power supply. In the related art, there is room for further improvement in such a structure in terms of improving the bonding strength between the terminal and the electrode layer.

The terminal41according to the embodiment is in contact with the first electrode layer111at the tip surface411thereof and the side surface412thereof. Thus, the bonding strength between the terminal41and the first electrode layer111can be improved compared to a case in which, for example, the terminal41is in contact with the first electrode layer111only at the tip surface411thereof or only at the side surface412thereof.

The terminal41and the first electrode layer111are bonded, for example, by heat-shrinking the first electrode layer111to adhere to the terminal41in a manufacturing process of the base10. Further, the terminal41and the first electrode layer111may also be bonded by interposing a sealant (not illustrated) in a minute gap between the terminal41and the first electrode layer111. The sealant contains, for example, aluminum oxide (Al2O3) as a main component, and calcium oxide (CaO) and yttrium oxide (Y2O3).

The first electrode layer111to be connected to the terminal41has a contact portion15at a portion in contact with the terminal41. The contact portion15is a part of the first electrode layer111, and a thickness (width in the up-down direction) thereof is thicker than that of other portions in the first electrode layer111. Specifically, the contact portion15protrudes toward the lower surface102side, that is, toward the opposite side of the wafer placement surface101, compared to the other portions of the first electrode layer111. As an example, the thickness of the contact portion15(maximum thickness excluding a recessed portion151described later) is 0.4 mm to 3 mm, preferably 0.6 mm to 2 mm.

In this way, by making the contact portion15, which is the contact portion with the terminal41, thicker than the other portions, the contact area with the side surface412of the terminal41can be made larger. Thus, the bonding strength between the terminal41and the first electrode layer111can be further improved. In addition, as will be described in detail later, when forming a recessed portion for housing the tip portion410of the terminal41using a drill or the like in the first electrode layer111in the manufacturing process of the base10, it is possible to reduce the likelihood of the drill or the like accidentally passing through the first electrode layer111. That is, the manufacturing process of the base10can be facilitated.

Further, the base10has a space17around the contact portion15. The space17extends to a side of the contact portion15, and surrounds the entire circumference of the contact portion15. By providing the space17around the contact portion15in this manner, it is possible to suppress the heat transfer to the opposite side of the wafer placement surface101due to the insulating effect of the space17. Thus, it is possible to efficiently heat the wafer placed on the wafer placement surface101.

Manufacturing Method for Base According to Embodiment

Next, an example of a manufacturing method for the base10will be described with reference toFIGS.4to9.FIGS.4to9are schematic cross-sectional views for describing the example of the manufacturing method for the base10according to the embodiment.

As illustrated inFIG.4, first, a plurality of ceramic green sheets201containing aluminum nitride (AlN) or the like as a main component are layered on one another. On top of that, one (or a plurality of) metal sheet202made of a metal or alloy such as tungsten (W), which constitutes the first electrode layer111, is layered, and then a plurality of ceramic green sheets201are further layered thereon. The plurality of ceramic green sheets201layered on the metal sheet202are preliminarily formed with an opening203for positioning the contact portion15described above.

Subsequently, as illustrated inFIG.5, the opening203is filled with tungsten carbide (WC) paste204. Note that the paste204may be one that is eventually integrated with the first electrode layer111, and does not necessarily have to be tungsten carbide. The paste204filled in the opening203is dried in the opening203. Subsequently, as illustrated inFIG.6, a plurality of ceramic green sheets201are further layered thereon.

Subsequently, the laminate is then fired at a temperature of 1700 to 1800° C., for example, under a nitrogen atmosphere. As a result, as illustrated inFIG.7, the paste204is integrated with the first electrode layer111to form the contact portion15. In addition, the space17is formed on the side of the contact portion15due to the shrinkage of the paste204.

Subsequently, as illustrated inFIG.8, an opening205is formed in the base10. The opening205is formed by using, for example, a drill or the like so as to extend in the up-down direction from the lower surface102toward the wafer placement surface101(seeFIG.2, etc.) of the base10. At this time, a part of the contact portion15is also drilled by the drill or the like as well as the base10. This forms a recessed portion151in a part of the contact portion15that is recessed in the thickness direction of the contact portion15.

Subsequently, as illustrated inFIG.9, the terminal41is inserted into the opening205(seeFIG.8). This positions the tip portion410of the terminal41inside the recessed portion151of the contact portion15. Subsequently, a sealant206is applied around the terminal41. Thereafter, the base10is thermally treated, for example, at 1550° C. in a vacuum. This allows the sealant206to enter a gap between the terminal41and the opening205by capillary action, thereby sealing the gap between the terminal41and the opening205. Further, the terminal41and the first electrode layer111are bonded to each other.

Note that, before inserting the terminal41into the opening205, a paste containing metal fine particles of Pt (platinum) or Ni (nickel) as a main component may be applied to a tip of the terminal41(on a side in contact with the recessed portion151). By applying Pt paste or Ni paste to the tip of the terminal41and then inserting the terminal41into the opening205, the terminal41and the recessed portion151(contact portion15) are bonded with Pt or Ni interposed therebetween. This increases the bonding strength between the terminal41and the contact portion15, thereby increasing the reliability of the bonding between the terminal41and the contact portion15.

FIRST MODIFICATION EXAMPLE

Next, a modification example of the structure2according to the above-described embodiment will be described. First, a structure according to a first modification example will be described with reference toFIG.10.FIG.10is a schematic cross-sectional view of the structure according to the first modification example.

As illustrated inFIG.10, a structure2A according to the first modification example includes a base10A. The base10A has a space17A larger than the space17that the base10according to the above-described embodiment has. Specifically, whereas the space17that the base10according to the above-described embodiment has extends only to the side of the contact portion15, the space17A extends to the side and also in the protruding direction (here, in the negative direction of the Z axis) of the contact portion15. In other words, the space17A is interposed between a side surface152of the contact portion15and the base10A, and is also interposed between a protruding surface153(an end surface protruding more than other portions of the first electrode layer111) of the contact portion15and the base10A.

As described above, by having the space17A around the contact portion15that extends to the side and in the protruding direction of the contact portion15, it is possible to further suppress heat transfer to the opposite side of the wafer placement surface101due to the insulating effect of the space17A. In addition, as will be described later, in a manufacturing process of the base10A, the work of forming the recessed portion151in the contact portion15can be facilitated.

Manufacturing Method for Base According to First modification Example

Next, a manufacturing method for the base10A according to the first modification example will be described with reference toFIGS.11to15.FIGS.11to15are schematic cross-sectional views for describing an example of the manufacturing method for the base10A according to the first modification example.

As illustrated inFIG.11, after a plurality of ceramic green sheets201and the metal sheet202are layered in a procedure similar to that for the base10according to the above-described embodiment, the opening203is filled with the tungsten carbide (WC) paste204. The paste204fills the opening203, leaving some space. Subsequently, after the opening203is further filled with a resin207, a plurality of ceramic green sheets201are further layered thereon as illustrated inFIG.12.

Subsequently, the laminate is then fired at a temperature of 1700 to 1800° C., for example, under a nitrogen atmosphere. As a result, as illustrated inFIG.13, the paste204is integrated with the first electrode layer111to form the contact portion15. In addition, in this step, the space17A is formed around the contact portion15due to the shrinkage of the paste204and the burning of the resin207.

Although it is possible to form the space17A without filling the opening203(seeFIG.11) with the resin207, filling the opening203with the resin207can suppress the distortion of the base10A after firing. Specifically, since the shrinkage rate of the paste204is larger than that of others, the region around the paste204(contact portion15) is easily distorted by firing, but by filling the opening203with the resin207, such distortion can be suppressed.

Subsequently, as illustrated inFIG.14, the opening205is formed in the base10A. The opening205is formed by using, for example, a drill or the like so as to extend in the up-down direction from the lower surface102toward the wafer placement surface101(seeFIG.2, etc.) of the base10A. As a result, first, the outside of the base10A and the space17A inside the base10A communicate with each other through the opening205. Subsequently, the protruding surface153of the contact portion15is drilled by a drill or the like to form the recessed portion151in a part of the contact portion15that is recessed in the thickness direction of the contact portion15. At this time, since the space17A is interposed between the opening205and the protruding surface153of the contact portion15, it is easy for the operator to visually confirm the protruding surface153of the contact portion15through the opening205. Thus, positioning of the recessed portion151can be easily performed.

Subsequently, as illustrated inFIG.15, the terminal41is inserted into the opening205. This positions the tip portion410of the terminal41inside the recessed portion151of the contact portion15. Subsequently, the sealant206is applied around the terminal41. Thereafter, the base10is thermally treated, for example, at 1550° C. in a vacuum. This allows the sealant206to enter the gap between the terminal41and the opening205by capillary action, thereby sealing the gap between the terminal41and the opening205. Further, the terminal41and the first electrode layer111are bonded to each other.

SECOND MODIFICATION EXAMPLE

Next, a structure according to a second modification example will be described with reference toFIG.16.FIG.16is a schematic cross-sectional view of the structure according to the second modification example. Note that inFIG.16andFIGS.17to27, which will be described later, only the first electrode layer and the terminal are illustrated, and other configurations are omitted from the figures.

As illustrated inFIG.16, in a structure2B according to the second modification example, the terminal41is connected at a position offset from a center position of the contact portion15. In this way, the terminal41does not necessarily have to be connected to the center position of the contact portion15.

THIRD MODIFICATION EXAMPLE

Next, a structure according to a third modification example will be described with reference toFIG.17.FIG.17is a schematic cross-sectional view of the structure according to the third modification example.

As illustrated inFIG.17, a structure2C according to the third modification example has a first electrode layer111C. A contact portion15C of the first electrode layer111C according to the third modification example has a plurality of protruding surfaces153aand153bhaving different protruding heights. Thus, the protruding surfaces153aand153bof the contact portion15C do not necessarily have to be the same surface.

FOURTH MODIFICATION EXAMPLE

Next, a structure according to a fourth modification example will be described with reference toFIG.18.FIG.18is a schematic cross-sectional view of the structure according to the fourth modification example.

As illustrated inFIG.18, a structure2D according to the fourth modification example includes a first electrode layer111D. A contact portion15D of the first electrode layer111D according to the fourth modification example has a curved corner portion155D between a side surface152D and a protruding surface153D. In this way, by making the corner portion155D of the contact portion15D curved, stress concentration on the contact portion15D can be reduced.

FIFTH MODIFICATION EXAMPLE

Next, a structure according to a fifth modification example will be described with reference toFIG.19.FIG.19is a schematic cross-sectional view of the structure according to the fifth modification example.

As illustrated inFIG.19, a structure2E according to the fifth modification example includes a first electrode layer111D. A contact portion15E of the first electrode layer111D according to the fifth modification example has a curved corner portion156E between a side surface152E and another portion of the first electrode layer111D. In this way, by making the corner portion156E of the contact portion15E curved, stress concentration on the contact portion15E can be reduced.

SIXTH MODIFICATION EXAMPLE

Next, a structure according to a sixth modification example will be described with reference toFIG.20.FIG.20is a schematic cross-sectional view of the structure according to the sixth modification example.

As illustrated inFIG.20, a structure2F according to the sixth modification example includes a first electrode layer111F. The first electrode layer111F according to the sixth modification example is curved toward the terminal41with a contact portion15F as the center. In this way, the first electrode layer111F is curved toward the terminal41, making it easier for the first electrode layer111F to resist the pressing force by the terminal41. This makes the bond between the terminal41and the first electrode layer111F more reliable.

The first electrode layer111F only needs to be curved toward the terminal41at least in some region including the contact portion15F, and does not necessarily have to be curved on the whole.

In addition, although an example in which the first electrode layer111F is curved toward the terminal41is described here, the first electrode layer111F may be curved toward the wafer placement surface101, for example.

SEVENTH MODIFICATION EXAMPLE

Next, a structure according to a seventh modification example will be described with reference toFIG.21.FIG.21is a schematic cross-sectional view of the structure according to the seventh modification example.

As illustrated inFIG.21, a structure2G according to the seventh modification example includes a terminal41G. The terminal41G according to the seventh modification example has a reduced diameter portion413G that decreases in diameter from a side surface412G toward a tip surface411G between the tip surface411G and the side surface412G. For example, the reduced diameter portion413G according to the seventh modification example is a chamfered corner portion located between the tip surface411G and the side surface412G of the terminal41G. Here, a case in which the reduced diameter portion413G has a chamfered surface is illustrated, but the reduced diameter portion413G may have a rounded surface.

In this way, by providing the reduced diameter portion413G at a tip portion410G of the terminal41G, the contact area between the tip portion410G of the terminal and the contact portion15can be increased. Thus, the bonding strength between the terminal41G and the first electrode layer111can be further improved.

EIGHTH MODIFICATION EXAMPLE

Next, a structure according to an eighth modification example will be described with reference toFIG.22.FIG.22is a schematic cross-sectional view of the structure according to the eighth modification example.

As illustrated inFIG.22, a structure2H according to the eighth modification example includes a terminal41H. The terminal41H according to the eighth modification example has a reduced diameter portion413H that decreases in diameter from a side surface412H toward a tip surface411H. The reduced diameter portion413H according to the eighth modification example is a stepped portion located between the tip surface411H and the side surface412H.

In this way, by providing the reduced diameter portion413H having a stepped shape at a tip portion410H of the terminal41H, the bonding strength between the terminal41H and the first electrode layer111can be further improved.

NINTH MODIFICATION EXAMPLE

Next, a structure according to a ninth modification example will be described with reference toFIG.23.FIG.23is a schematic cross-sectional view of the structure according to the ninth modification example.

As illustrated inFIG.23, a structure21according to the ninth modification example includes a terminal41I. The terminal41I according to the ninth modification example has a tip surface411I having a curved surface. In this way, by making the tip surface411I of the terminal41I curved, the contact area between a tip portion410I of the terminal41I and the contact portion15can be increased. Thus, the bonding strength between the terminal41I and the first electrode layer111can be further improved.

10TH MODIFICATION EXAMPLE

Next, a structure according to a 10th modification example will be described with reference toFIG.24.FIG.24is a schematic cross-sectional view of the structure according to the 10th modification example.

As illustrated inFIG.24, a structure2J according to the 10th modification example includes a terminal41J. The terminal41J according to the 10th modification example has a tapered shape in which a side surface412J decreases in diameter toward a tip surface411J. In this way, by making a tip portion410J of the terminal41J tapered, the contact area between the tip portion410J of the terminal41J and the contact portion15can be increased. Thus, the bonding strength between the terminal41J and the first electrode layer111can be further improved.

11TH MODIFICATION EXAMPLE

Next, a structure according to an 11th modification example will be described with reference toFIG.25.FIG.25is a schematic cross-sectional view of the structure according to the 11th modification example.

As illustrated inFIG.25, a structure2K according to the 11th modification example includes a terminal41K. The terminal41K according to the 11th modification example has a reverse tapered shape in which a side surface412K increases in diameter toward a tip surface411K. In this way, by making a tip portion410K of the terminal41K have a reverse tapered shape, the contact area between the tip portion410K of the terminal41K and the contact portion15can be increased. Thus, the bonding strength between the terminal41K and the first electrode layer111can be further improved. In addition, the reverse tapered shape suppresses the separation of the terminal41K.

12TH MODIFICATION EXAMPLE

Next, a structure according to a 12th modification example will be described with reference toFIG.26.FIG.26is a schematic cross-sectional view of the structure according to the 12th modification example.

As illustrated inFIG.26, a structure2L according to the 12th modification example extends diagonally with respect to the protruding direction of the contact portion15(here, the Z axis direction). In this way, a terminal41L may extend diagonally with respect to the protruding direction of the contact portion15, in other words, the thickness direction of the base (up-down direction). This allows the thermal expansion of the terminal41L to be shifted in the right-left direction, thereby suppressing the cracks in the base.

13TH MODIFICATION EXAMPLE

Next, a structure according to a 13th modification example will be described with reference toFIG.27.FIG.27is a schematic cross-sectional view of the structure according to the 13th modification example.

As illustrated inFIG.27, a structure2M according to the 13th modification example includes a first electrode layer111M. A contact portion15M of the first electrode layer111M according to the 13th modification example has a gap208between a part of a bottom surface151ain the recessed portion151and a part of the tip surface411in the terminal41. In this way, by having the gap208, thermal conduction from the first electrode layer111M to the terminal41can be suppressed. Thus, the heat generated in the first electrode layer111M can be efficiently transferred to the wafer.

14TH MODIFICATION EXAMPLE

Next, a structure according to a 14th modification example will be described with reference toFIG.28.FIG.28is a schematic cross-sectional view of the structure according to the 14th modification example.

As illustrated inFIG.28, a structure2N according to the 14th modification example includes a first electrode layer111N. A contact portion15N of the first electrode layer111N according to the 14th modification example protrudes toward the wafer placement surface101(seeFIG.2) side compared to other portions of the first electrode layer111N. In this way, the contact portion15N does not need to protrude toward the lower surface102of the base10like the contact portion15illustrated inFIG.3, for example, but may protrude toward the wafer placement surface101.

15TH MODIFICATION EXAMPLE

Next, a structure according to a 15th modification example will be described with reference toFIG.29.FIG.29is a schematic cross-sectional view of the structure according to the 15th modification example.

As illustrated inFIG.29, a structure20according to the 15th modification example includes a first electrode layer111O. A contact portion15O of the first electrode layer111O according to the 15th modification example protrudes toward the wafer placement surface101(seeFIG.2) side of the base10as well as toward the lower surface102side of the base10compared with other portions of the first electrode layer111O. In this way, the contact portion15O may protrude toward both the wafer placement surface101and the lower surface102. This makes it possible to increase the contact area between the terminal41and the contact portion15O. Thus, the bonding strength between the terminal41and the first electrode layer111O can be further improved.

16TH MODIFICATION EXAMPLE

Next, a structure according to a 16th modification example will be described with reference toFIG.30.FIG.30is a schematic cross-sectional view of the structure according to the 16th modification example.

As illustrated inFIG.30, a structure2P according to the 16th modification example includes a first via conductor113aand a second via conductor113b.

In this way, by connecting the first electrode layer111and the second electrode layer112using a plurality of via conductors (first via conductor113aand second via conductor113b), it is possible to make the electrical connection between the first electrode layer111and the second electrode layer112more secure.

Further, when the structure2P is used, the first electrode layer111and the second electrode layer112expand or contract in the horizontal direction (direction along the wafer placement surface101) due to changes in temperature. Such deformation of the first electrode layer111and the second electrode layer112may cause cracks in the base10. In contrast, in the structure2P according to the 16th modification example, the first electrode layer111and the second electrode layer112are connected by the plurality of via conductors (first via conductor113aand second via conductor113b). Thus, according to the structure2P according to the 16th modification example, thermal deformation of the first electrode layer111and the second electrode layer112can be suppressed by the plurality of via conductors. Thus, it is possible to suppress cracks in the base10.

Moreover, the first via conductor113aand the second via conductor113bare located on both sides of the contact portion15, respectively. For example, in the example illustrated inFIG.30, the first via conductor113ais located on the left side of the contact portion15on the paper surface, and the second via conductor113bis located on the right side of the contact portion15on the paper surface. In this way, by having the first via conductor113aand the second via conductor113blocated on both sides of the contact portion15, thermal deformation of the first electrode layer111and the second electrode layer112, especially around the contact portion15, can be suppressed. Thus, for example, when the structure2P is used, it is possible to suppress separation of the terminal41from the first electrode layer111due to thermal deformation of the first electrode layer111and the second electrode layer112. In other words, it is possible to increase the bonding strength between the terminal41and the first electrode layer111in an operation environment in which the temperature is repeatedly raised and lowered.

17TH MODIFICATION EXAMPLE

Next, a structure according to a 17th modification example will be described with reference toFIGS.31and32.FIG.31is a schematic cross-sectional view of the structure according to the 17th modification example.FIG.32is a schematic top view of a terminal according to the 17th modification example.

As illustrated inFIG.31, a structure2Q according to the 17th modification example includes a terminal41Q. As illustrated inFIGS.31and32, the terminal41Q has a recessed portion415on the side surface412. The recessed portion415is provided at the tip portion410of the terminal41Q. Specifically, on the side surface412of the terminal41Q, the recessed portion415is continuously provided from a portion facing the contact portion15to a portion facing the base10.

The sealant206enters such a recessed portion415. In other words, the recessed portion415is filled with the sealant206.

In this way, by allowing the sealant206to enter the recessed portion415, the bonding strength between the terminal41Q and the base10can be improved. In addition, by allowing the sealant206to enter the recessed portion415, the bonding strength between the terminal41Q and the contact portion15can be improved. Further, even when more than the required amount of the sealant206(e.g., pt (platinum)) is applied in the manufacturing process, the excess sealant206accumulates in the recessed portion415, thereby suppressing seepage of the sealant206from the lower surface102of the base10during manufacturing, for example.

Note that, although a case in which the terminal41Q has one recessed portion415is illustrated here, the number of recessed portions415possessed by the terminal41Q may be two or more. In addition, the recessed portion415may extend from the tip surface411to a base end surface of the terminal41Q.

18TH MODIFICATION EXAMPLE

Next, a structure according to an 18th modification example will be described with reference toFIGS.33and34.FIG.33is a schematic cross-sectional view of the structure according to the 18th modification example.FIG.34is a schematic top view of a terminal according to the 18th modification example.

As illustrated inFIG.33, a structure2R according to the 18th modification example includes a terminal41R. As illustrated inFIGS.33and34, the terminal41R has a recessed portion416on the tip surface411. The recessed portion416is provided at the tip portion410of the terminal41R. Specifically, the recessed portion416is provided on the tip surface411of the terminal41R. Both ends of the recessed portion416reach the side surface412of the terminal41R. Note that, although a case in which the terminal41R has one recessed portion416is illustrated here, the terminal41R may have a plurality of recessed portions416. For example, the terminal41R may have two recessed portions416that intersect in a cross. The terminal41R may further have a recessed portion415similar to the recessed portion415possessed by the terminal41Q according to the 17th modification example. In this case, the recessed portion415and the recessed portion416may be contiguous.

In such a recessed portion416, the sealant206is entered. In other words, the recessed portion416is filled with the sealant206.

In this way, by allowing the sealant206to enter the recessed portion416, the bonding strength between the terminal41R and the base10can be improved. In addition, by allowing the sealant206to enter the recessed portion416, the bonding strength between the terminal41R and the contact portion15can be improved. Further, even when more than the required amount of the sealant206(e.g., pt (platinum)) is applied in the manufacturing process, the excess sealant206accumulates in the recessed portion416, thereby suppressing seepage of the sealant206from the lower surface102of the base10during manufacturing, for example.

As described above, the structures (e.g., structures2,2A to2P) according to the respective embodiments include the respective bases (e.g.,10,10A), the respective electrode layers (e.g., first electrode layers111,111C,111D,111F,111M,111N,111O), and the respective terminals (e.g., terminals41,41G,41H,41I,41J,41K,41L). The base is made of a ceramic. The electrode layer is located inside the base. The terminal is electrically connected to the electrode layer at the tip portion of the terminal. Further, the terminals are in contact with the respective electrode layers at the respective tip surfaces (e.g., tip surfaces411,411G,411H,411I,411J,411K) of the terminals and the respective side surfaces (e.g., side surfaces412,412G,412H,412J,412K) of the terminals. Thus, according to the structures according to the respective embodiments, the bonding strength between the terminal and the electrode layer can be improved.

The electrode layers may have the respective contact portions (e.g., contact portions15,15C,15D,15E,15F,15M,15N,15O) with the respective terminals. In this case, each of the contact portions may be thicker than the other portions in the electrode layer. By making the contact portion, which is the portion in contact with the terminal, thicker than the other portions in the electrode layer, the contact area with the side surface of the terminal can be made larger. Thus, the bonding strength between the terminal and the electrode layer can be further improved.

The electrode layer may have the recessed portion (e.g., recessed portion151) in a part of the contact portion that is recessed in the thickness direction of the contact portion. In this case, the tip portion of the terminal may be located inside the recessed portion. Since the contact portion is thickly formed, when the recessed portion is formed in the contact portion using a drill or the like in the manufacturing process of the base, the likelihood of the drill or the like accidentally passing through the electrode layer can be reduced. That is, the manufacturing process of the base can be facilitated.

The structure according to the embodiment (e.g., structure2M) may have the gap (e.g., gap208) between a part of the bottom surface of the recessed portion and a part of the tip surface of the terminal. This makes it possible to suppress thermal conduction from the electrode layer to the terminal.

The electrode layer (e.g., electrode layer111F) may be curved toward the terminal at least in the region including the contact portion. This makes it easier for the electrode layer to resist the pressing force by the terminal, thereby ensuring a more secure bond between the terminal and the electrode layer.

The bases (e.g., bases10,10A) may have the respective spaces (e.g., spaces17,17A) around the contact portion. This makes it possible to suppress thermal conduction in the direction in which the space is present due to the insulating effect of the space.

The space (e.g., space17A) may extend to the side and in the protruding direction of the contact portion. This makes it possible to further suppress thermal conduction in the direction in which the space is present.

The terminal (e.g., terminal41J) may have a shape that decreases in diameter toward the tip surface (e.g., tip surface411J). This makes it possible to increase the contact area between the tip portion of the terminal and the contact portion. Thus, the bonding strength between the terminal and the electrode layer can be further improved.

The terminal (e.g., terminal41K) may have a shape that increases in diameter toward the tip surface (e.g., tip surface411K). This makes it possible to increase the contact area between the tip portion of the terminal and the contact portion. Thus, the bonding strength between the terminal and the electrode layer can be further improved. In addition, the reverse tapered shape suppresses the separation of the terminal.

The tip surface (e.g., tip surface411I) of the terminal (e.g., terminal41I) may be curved. This makes it possible to increase the contact area between the tip portion of the terminal and the contact portion. Thus, the bonding strength between the terminal and the electrode layer can be further improved.

In the above-described embodiments, the wafer placement device has been described as an example of the heating device, but the heating device according to the present disclosure is not limited to the wafer placement device as long as heat is generated in the electrode layer inside the base to heat an object (e.g., an object placed on one side of the base).

Additional effects and variations can be easily derived by a person skilled in the art. Thus, a wide variety of aspects of the present invention are not limited to the specific details and representative embodiments represented and described above. Accordingly, various changes are possible without departing from the spirit or scope of the general inventive concepts defined by the appended claims and their equivalents.

REFERENCE SIGNS LIST