JP7748280B2 - Electrode embedding member, substrate holding member, ceramic heater, and electrostatic chuck - Google Patents

Description

The present invention relates to an electrode embedding member, a substrate holding member, a ceramic heater, and an electrostatic chuck.

Embedded electrode components with embedded electrodes (heat generating resistors) have been used as components for semiconductor manufacturing equipment. These components are capable of heating the substrate placed on them. Embedded electrode components are required to have uniform heating surfaces, and various proposals have been made.

Patent Document 1 discloses a substrate heating device in which the heating surface of the ceramic base on which the substrate is placed has a convex shape that is highest in the center and becomes lower as it approaches the periphery. This improves adhesion to the substrate in the center, where heat is easily lost due to heat transfer from the shaft, thereby achieving a uniform temperature distribution on the heating surface.

Patent Document 2 discloses a ceramic heater with an embossed portion on the heating surface that comes into contact with the substrate. It also describes that when the average temperature of the heating surface rises to a target temperature, a heat spot with a relatively high surface temperature occurs on the heating surface. The ceramic heater described in Patent Document 2 reduces the impact of the heat spot on the substrate by reducing the number of embossed portions per unit area in the heat spot compared to areas other than the heat spot.

Japanese Patent Application Laid-Open No. 2005-109169 Japanese Patent Application Laid-Open No. 2002-124367

In recent years, there has been a demand not only for uniform heating of the heating surface, but also for creating a temperature gradient when precisely controlling the film deposition distribution at each position on the substrate. This has led to a demand for technology that can suppress localized temperature distributions that have a negative effect on the substrate, such as hot spots and heat spots, to achieve a uniform temperature distribution while also creating a desired temperature gradient in the radial direction.

Patent Document 1 takes into consideration the uniformity of the temperature distribution on the heating surface, but does not consider the suppression of localized temperature distribution such as hot spots, or the creation of a desired temperature gradient in the radial direction. Furthermore, Patent Document 2 reduces the impact of heat spots on the substrate, but does not consider the creation of a desired temperature gradient in the radial direction.

The present invention was made in light of these circumstances, and aims to provide an electrode embedding member, substrate holding member, ceramic heater, and electrostatic chuck that achieves uniform local temperature distribution and makes it possible to create a predetermined temperature gradient.

(1) In order to achieve the above object, the electrode-embedding member of the present invention is an electrode-embedding member comprising a base formed in a disk shape from a ceramic sintered body, an electrode embedded in the base, and a plurality of pin-shaped protrusions formed and protruding upward from the upper surface of the base, wherein the upper surface of the base is formed as a curved surface that is convex toward the center, and the plurality of pin-shaped protrusions include first pin-shaped protrusions that have approximately the same height from the upper surface to their upper ends, and second pin-shaped protrusions that have a height from the upper surface to their upper ends that is lower than the height of the first pin-shaped protrusions, and wherein the second pin-shaped protrusions are formed in a ring-shaped region surrounded by concentric circles centered at the center of the upper surface.

In this way, when the support surface formed by the upper ends of the first pin-shaped protrusions is a convex curved surface, by providing second pin-shaped protrusions that are lower than the first pin-shaped protrusions in a ring-shaped region, it is possible to achieve uniform local temperature distribution on the substrate and to create a predetermined temperature gradient in the radial direction.

(2) Furthermore, in the electrode-embedded member of the present invention, when the difference in height between the first pin-shaped protrusion and the second pin-shaped protrusion that is the shortest among the second pin-shaped protrusions is ΔG, and the difference in the vertical direction between the upper end of the first pin-shaped protrusion closest to the center of the base and the upper end of the first pin-shaped protrusion closest to the outer edge of the base is ΔH, the relationship ΔH > ΔG ≧ 0.5 × ΔH is satisfied.

In this way, by lowering the second pin-shaped protrusions by a certain amount or more, it is possible to make it less likely for the substrate and the second pin-shaped protrusions to come into contact with each other in the electrode-embedded member that adheres the substrate to the base, even if the substrate is deformed by suction force. This reduces the risk of complicated temperature control of the substrate above the second pin-shaped protrusions, which requires consideration of whether or not the second pin-shaped protrusions and the substrate are in contact.

(3) In the electrode-embedding member of the present invention, the two cross-sectional curves obtained by cutting the mounting surface formed by the upper ends of the first pin-shaped convex portions at two cross sections passing through the central axis, with a vertical line passing through the center of the base as the central axis, are characterized in that the coefficient of determination ^R2 for the approximation equation when each of the cross-sectional curves is approximated by a quadratic curve is 0.99 or more.

This allows for the creation of a convex curved mounting surface with high central symmetry, improving the circumferential temperature uniformity of the substrate and making it easier to control the local temperature distribution of the substrate and to create a specified temperature gradient.

(4) The substrate holding member of the present invention is characterized by comprising an electrode-embedded member according to any one of (1) to (3) above, and a support member bonded to the lower surface of the substrate opposite the upper surface and supporting the electrode-embedded member.

This allows the ring-shaped area to be adjusted according to the size, position, thermal conductivity, etc. of the support member, making it possible to achieve uniform local temperature distribution on the substrate even in the substrate holding member, and to create a predetermined temperature gradient.

(5) The ceramic heater of the present invention is characterized in that it includes the substrate holding member described in (4) above, and the electrodes are heater electrodes.

This allows the ring-shaped area to be adjusted according to the size, position, thermal conductivity, etc. of the support member, making it possible to achieve uniform local temperature distribution on the substrate even with a ceramic heater, and to create a specified temperature gradient.

(6) The electrostatic chuck of the present invention is an electrostatic chuck comprising the substrate holding member described in (4) above, wherein the electrode is a heater electrode, and the substrate holding member further comprises an electrostatic attraction electrode.

This allows the ring-shaped area to be adjusted according to the size, position, thermal conductivity, etc. of the support member, making it possible to achieve uniform local temperature distribution on the substrate even in an electrostatic chuck, and to create a predetermined temperature gradient.

The electrode embedding member, substrate holding member, ceramic heater, and electrostatic chuck of the present invention can achieve uniform local temperature distribution and create a predetermined temperature gradient.

1 is a schematic cross-sectional view showing an example of an electrode-embedded member according to an embodiment of the present invention. 3A and 3B are schematic diagrams illustrating an example of the upper surface of an electrode embedded in an electrode-embedding member according to the embodiment. 2 is a schematic diagram showing an example of the upper surface of an electrode-embedded member according to an embodiment of the present invention. FIG. 1 is a schematic diagram illustrating an example of an electrode-embedded member according to an embodiment of the present invention. 1 is a schematic partial cross-sectional view showing an example of an electrode-embedding member according to an embodiment of the present invention. FIG. 10 is a schematic partial cross-sectional view showing an example of a modified example of an electrode-embedding member according to an embodiment of the present invention. FIG. 10 is a schematic partial cross-sectional view showing an example of a modified example of an electrode-embedding member according to an embodiment of the present invention. FIG. 10 is a schematic partial cross-sectional view showing an example of the upper surface of a modified example of an electrode-embedding member according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing an example of a substrate holding member according to an embodiment of the present invention. 5A to 5C are schematic diagrams illustrating an example of a manufacturing process for an electrode-embedded member according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view showing an example of a ceramic heater according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing an example of an electrostatic chuck according to an embodiment of the present invention.

Next, an embodiment of the present invention will be described with reference to the drawings. To facilitate understanding, the same reference numbers will be used in each drawing to refer to the same components, and duplicate explanations will be omitted. Note that in the structural diagrams, the size of each component is shown conceptually and does not necessarily represent the actual dimensional ratio.

[Embodiment]
(Configuration of electrode-embedded member)
An electrode-embedding member according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5 . FIG. 1 is a schematic cross-sectional view showing an example of an electrode-embedding member according to an embodiment of the present invention. FIG. 2 is a schematic view showing an example of the upper surface of an electrode according to an embodiment of the present invention. FIG. 3 is a schematic view and a partially enlarged view showing an example of the upper surface of an electrode-embedding member according to an embodiment of the present invention. FIG. 4 is a schematic partial cross-sectional view showing an example of an electrode-embedding member according to an embodiment of the present invention. FIG. 5 is a schematic partially enlarged cross-sectional view showing an example of an electrode-embedding member according to an embodiment of the present invention. The terminal 50 and the terminal hole 52 are omitted from the partial cross-sectional view. The electrode-embedding member 100 according to this embodiment includes a base 10, an electrode 20, and a pin-shaped protrusion 30 including a first pin-shaped protrusion 31 and a second pin-shaped protrusion 32.

The base 10 is made of a sintered ceramic body and is roughly disc-shaped, with the top surface 12 of the base 10 formed as a convex curved surface toward the center 16. The shape of the base 10 naturally determines the center 16 of the base 10.

The electrode 20 is embedded in the base 10. The electrode 20 is used as a heater electrode for heating the substrate W (wafer). Terminals 50 are connected to both ends of the electrode 20. Electrodes used for other purposes, such as an electrostatic adsorption electrode or a high-frequency electrode, may also be embedded.

The electrode 20 may have any shape, including a shape that includes multiple circumferential patterns as shown in Figure 2. The temperature distribution and localized hot spots on the heating surface of the substrate 10 may depend on the shape of the electrode 20. For example, if the shape of the electrode 20 is such that multiple circumferential patterns are connected as shown in Figure 2, the temperature distribution on the heating surface is less likely to have temperature differences in the circumferential direction, but is more likely to occur in the radial direction. However, the electrode-embedded member 100 of the present invention can reduce or control this.

As shown in Figure 1, multiple pin-shaped protrusions 30 are formed and protrude upward from the upper surface 12 of the base 10. The shape of the pin-shaped protrusions 30 is appropriately selected from pillar shapes such as a cylindrical shape or a rectangular pillar shape, cone shapes such as a cone shape or a pyramid shape, and shapes with the top of a truncated cone shape such as a truncated cone shape or a pyramid shape.

The arrangement of the pin-shaped protrusions 30 is not particularly limited. They may be in a known form or a similar form, such as a regular arrangement such as concentric circles, a square lattice, or a triangular lattice, or an irregular arrangement with localized density variations. However, a concentric arrangement as shown in Figure 8 is more preferable. A concentric arrangement makes it easier to control the temperature distribution in the radial direction.

As described above, the pin-shaped protrusions 30 have first pin-shaped protrusions 31 and second pin-shaped protrusions 32. As shown in FIG. 1, the first pin-shaped protrusions 31 are formed so that the height from the upper surface 12 of the base 10 to the upper end 31a is approximately the same. The second pin-shaped protrusions 32 are arranged in a ring-shaped area RA as shown in FIGS. 1 and 3. The height from the upper surface 12 to the upper end 32a of the second pin-shaped protrusions 32 is shorter than the height of the first pin-shaped protrusions 31.

As shown in FIG. 4, the upper ends 31a of the first pin-shaped protrusions form a curved surface (curved mounting surface) of a predetermined shape on which the substrate W is placed. This allows the first pin-shaped protrusions 31 to support the substrate W. That is, the curved mounting surface formed by the upper ends 31a of the first pin-shaped protrusions is determined. This allows the upper ends 31a of the first pin-shaped protrusions to abut against the substrate W, supporting the substrate W. Note that in FIG. 4, the entire upper ends 31a of the first pin-shaped protrusions abut against the substrate W, but only a portion of the upper ends 31a of the first pin-shaped protrusions may abut against the substrate W.

The upper ends 32a of the second pin-shaped protrusions may or may not come into contact with the substrate W. Even if they do come into contact, the contact pressure will be lower than that of the first pin-shaped protrusions 31, so less heat will be transferred to the substrate W than in the area where the first pin-shaped protrusions 31 are formed. On the other hand, even if they do not come into contact, the upper ends 32a of the second pin-shaped protrusions are closer to the substrate W than the upper surface 12, so more heat will be transferred to the substrate W than if there were no pin-shaped protrusions.

The ring-shaped region RA is a region surrounded by concentric circles centered on the center 16. The ring-shaped region RA is a region of the substrate 10 where it is desired to have lower heat conduction from the electrode 20 than other regions, such as a region showing a localized temperature distribution such as a hot spot or heat spot, or a region where lower heat conduction is required to create a desired temperature gradient. By making the pin-shaped protrusions 30 arranged in the ring-shaped region RA second pin-shaped protrusions 32 lower than the first pin-shaped protrusions 31, it is possible to achieve uniform heating of the local temperature distribution, particularly the localized temperature distribution that occurs in the radial direction, and to create a predetermined temperature gradient in the radial direction. Note that the second pin-shaped protrusions 32 may be arranged outside the ring-shaped region RA.

It should be noted that not only one ring-shaped region RA but also multiple regions may be provided per base 10. Furthermore, as shown in FIG. 3, the ring-shaped region RA may include two or more second pin-shaped protrusions 32 in the radial direction (for example, two or more if the protrusions are formed concentrically), or may include only one. Having two or more second pin-shaped protrusions 32 in the ring-shaped region RA in the radial direction makes it easier to equalize the local temperature distribution. Furthermore, having only one second pin-shaped protrusion 32 in the ring-shaped region RA in the radial direction makes it easier to control the temperature distribution in detail.

Furthermore, since the height from the upper surface 12 of the base 10 to the upper end 31a of the first pin-shaped protrusion 31 is approximately the same, the curved mounting surface formed by the upper end 31a of the first pin-shaped protrusion is approximately the same as the curved surface of the upper surface 12 of the base 10. In other words, the curved mounting surface is approximately the same as the curved surface formed by the upper surface 12 of the base 10 shifted vertically by the height of the first pin-shaped protrusion 31. This makes it possible to achieve a uniform suction force when the electrode-embedded member 100 is used as a member that suctions a substrate W.

When the central axis of the base 10 (a straight line passing through the center 16 of the base 10 and perpendicular to the reference plane of the base 10) is taken as the Z axis and the cross-sectional curve 42 is cut through the curved mounting surface formed by the upper end 31a of the first pin-shaped protrusion 31 at a cross section passing through the Z axis, the cross-sectional curve 42 is a curve that, when the intersection of the predetermined reference plane and the cross section is taken as the X axis, has a maximum Z value near the central axis as shown in Figure 5 and monotonically decreases toward the outer edge 18 of the base 10.

The specified reference plane is a horizontal plane passing through the point on the upper surface 12 of the base 10 that is closest to the horizontal plane. Alternatively, a plane obtained by translating these horizontal planes upward or downward may also be used as the reference plane. Note that "near the central axis" refers to a range within 25 mm of the central axis.

In this way, the cross-sectional curve 42 of the curved mounting surface is a curve that reaches a maximum value of Z near the central axis and monotonically decreases toward the outer edge 18 of the base 10, which improves the ability of the substrate W to conform to the first pin-shaped protrusions 31 compared to increasing the flatness of the curved mounting surface to make it closer to a plane, thereby reducing the occurrence of localized hot spots. Furthermore, because the substrate W is supported by the first pin-shaped protrusions 31, particle entrapment can be suppressed, and the space below the substrate W can be used as a gas flow path if necessary.

The curved mounting surface can be estimated by measuring the upper end 31a of the first pin-shaped protrusion with a three-dimensional measuring device. However, it is important that when the substrate W is placed on or sucked onto the electrode-embedded member 100, the substrate W conforms to the curved mounting surface, and that the shape of the surface of the substrate W opposite the curved mounting surface (the surface of the substrate W) is an ideal curved surface. Therefore, when a 0.775 mm thick silicon wafer is placed on or sucked onto the surface opposite the curved mounting surface, the curved surface of the area excluding the ring-shaped area RA can be measured with a laser interferometer, and the curved surface can be estimated as the curved mounting surface. The same applies to the cross-sectional curve 42. The curved mounting surface may also be measured within a range 5 mm to 10 mm inside the outer edge 18 of the base 10. This is because measurement errors may be larger at positions closer to the outer edge 18.

Furthermore, it is preferable that the flatness of the curved mounting surface is 50 μm or less. This allows the substrate W to be mounted without wrinkling. The flatness of the curved mounting surface is the difference between the maximum and minimum Z values for all points on the curved mounting surface. The lower limit of the flatness varies depending on the diameter of the substrate 10 and the shape of the desired curved mounting surface, but is preferably 5 μm or more, for example.

Furthermore, when the curve obtained by cutting the mounting surface at a second cross section perpendicular to the X-axis and including the Z-axis is defined as the second cross section, and the intersection line between a predetermined reference plane and the second cross section is defined as the Y-axis, the coefficient of determination ^R2 for the first approximation equation when the cross section curve is quadratically approximated and the coefficient of determination ^R2 for the second approximation equation when the second cross section curve is quadratically approximated are preferably both 0.99 or greater. This allows the cross section curves in the X-axis and Y-axis directions to have a quadratic curve shape, suppressing localized and irregular changes in the height direction of the cross section curve, thereby further reducing the occurrence of localized hot spots. The coefficient of determination ^R2 can be calculated by dividing the regression sum of squares by the total sum of squares. The regression sum of squares is the sum of squared deviations of the predicted values of the response variable, and the total sum of squares is the sum of squared deviations of the observed values of the response variable. The approximation of the cross section curve may be limited to a range 5 mm to 10 mm inside the outer edge 18 of the base 10.

Furthermore, when the units of Z are μm, X and Y are mm, and the quadratic coefficient of the first approximation equation is a(X), and the quadratic coefficient of the second approximation equation is a(Y), it is preferable to satisfy 2(a(X) - a(Y))/(a(X) + a(Y))≦0.1. This forms a curved surface with good symmetry with respect to the Z axis, and suppresses localized, irregular changes in the height direction of the cross-sectional curve across the entire surface, thereby preventing the occurrence of hot spots. Note that a(X) and a(Y) have the same sign.

The height of the first pin-shaped protrusions 31 is preferably 5 μm or more and 300 μm or less, and more preferably 50 μm or more and 200 μm or less. The height of the first pin-shaped protrusions 31 refers to the distance from the upper surface 12 of the base 10 to the upper ends 31a of the pin-shaped protrusions. The upper ends 31a of the pin-shaped protrusions 31 preferably have a flat surface of a predetermined size. In this case, the maximum diameter of the flat surface of the upper ends 31a of the first pin-shaped protrusions 31 is preferably 50 μm or more and 5000 μm or less. The surface roughness Ra of the flat surface of the upper ends 31a of the first pin-shaped protrusions 31 is preferably 0.1 μm or more and 1.2 μm or less.

The height of the second pin-shaped protrusions 32 need only be lower than the first pin-shaped protrusions 31, and the second pin-shaped protrusions 32 may include pin-shaped protrusions 30 with multiple heights. In other words, the heights of the second pin-shaped protrusions 32 do not necessarily have to be the same. Note that the height of the second pin-shaped protrusions 32 refers to the height of the upper end 32a of the second pin-shaped protrusions 32 at the position closest to the outer edge 18 of the base 10.

Furthermore, as shown in FIG. 5 , when ΔG is the difference in height between the first pin-shaped protrusions 31 and the second pin-shaped protrusions 32 that have the lowest height, and ΔH is the vertical difference between the upper end 31a of the first pin-shaped protrusions 31 closest to the center 16 of the base 10 and the upper end 31a of the first pin-shaped protrusions 31 closest to the outer edge 18 of the base 10, it is preferable that ΔH > ΔG ≧ 0.5 × ΔH be satisfied. In this way, by lowering the second pin-shaped protrusions 32 by a certain amount or more, it is possible to make it difficult for the substrate W and the second pin-shaped protrusions 32 to come into contact with each other even if the substrate W is deformed by the suction force. This reduces the risk of complicated temperature control of the substrate W above the second pin-shaped protrusions 32, which requires consideration of whether or not there is contact between the second pin-shaped protrusions 32 and the substrate W.

The shape of the base 10 may also be such that the underside 14 of the base 10 is formed with a curve that is substantially the same as the curved mounting surface, as shown in Figure 6. This allows the thickness of the base 10 to be uniform.

The electrode-embedding member 100 may also be provided with a terminal 50, a terminal hole 52, a lift pin hole (not shown), a vent hole for use as a vacuum chuck, and an annular protrusion 35 as shown in Figures 7 and 8.

(Configuration of substrate holding member)
Next, the configuration of a substrate holding member according to an embodiment of the present invention will be described. Fig. 9 is a schematic cross-sectional view showing an example of a substrate holding member according to an embodiment of the present invention. A substrate holding member 150 according to this embodiment includes an electrode-embedding member 100 and a support member 110. The basic configuration of the electrode-embedding member 100 is as described above.

The support member 110 is made of a sintered ceramic body and supports the embedded electrode member 100. This allows the substrate holding member 150 to be used in heaters with shafts, electrostatic chucks with shafts, etc. The support member 110 is bonded via a bonding surface 112 to a predetermined position on the lower surface 14 opposite the upper surface 12 of the embedded electrode member 100. The bonding may be by solid-state bonding or by bonding using a bonding material. The support member 110 is preferably made of a sintered ceramic body having the same main component as the base 10 of the embedded electrode member 100.

The support member 110 may have any shape as long as it can support the electrode-embedded member 100, but a cylindrical shape is preferable. When the substrate holding member 150 is used, heat transfer between the electrode-embedded member 100 and the support member 110 can cause localized temperature distribution or hot spots on the heating surface of the substrate 10, depending on the shape of the support member 110. If the support member 110 is cylindrical, for example, the temperature distribution on the heating surface is likely to occur in the radial direction. However, the substrate holding member 150 of the present invention can reduce or control this. Note that a cylindrical shape includes a shape provided with a flange, etc.

(Configuration of ceramic heater)
Next, the configuration of a ceramic heater according to an embodiment of the present invention will be described with reference to Figure 11. The ceramic heater 160 according to this embodiment includes a substrate holding member 150, and the electrode 20 is a heater electrode. The basic configuration of the substrate holding member 150 is as described above. This allows the ring-shaped region to be adjusted according to the size, position, thermal conductivity, etc. of the support member 110, and the ceramic heater 160 can also achieve uniform local temperature distribution on the substrate W and provide a predetermined temperature gradient.

(Configuration of electrostatic chuck)
Next, the configuration of an electrostatic chuck according to an embodiment of the present invention will be described. FIG. 12 is a schematic cross-sectional view showing an example of an electrostatic chuck according to an embodiment of the present invention. The electrostatic chuck 170 according to this embodiment includes a substrate holding member 150, the electrode 20 being a heater electrode, and the substrate holding member 150 further including an electrostatic attraction electrode 175. The basic configuration of the substrate holding member 150 is as described above. This allows the ring-shaped region to be adjusted according to the size, position, thermal conductivity, etc. of the support member 110, thereby achieving uniform local temperature distribution on the substrate W and providing a predetermined temperature gradient in the electrostatic chuck 170. Note that terminals and the like connected to the electrostatic attraction electrode 175 are omitted from FIG. 12 .

[Method of manufacturing electrode-embedded member]
Next, a method for manufacturing an electrode-embedded member according to an embodiment of the present invention will be described. The electrode-embedded member according to an embodiment of the present invention is manufactured, for example, by powder hot pressing. The powder hot pressing method involves alternately stacking ceramic raw material powder and predetermined electrodes to embed the electrodes inside the ceramic, and then uniaxial hot pressing and firing the resulting material. The use of powder hot pressing allows for manufacturing in a short period of time. However, the manufacturing method is not limited to this method, and may also be, for example, the molded body hot pressing method disclosed in Japanese Patent No. 6,148,845, or a conventional green sheet lamination method.

For example, ceramic powder is mixed with additives such as sintering aids, binders, plasticizers, and dispersants to produce a ceramic raw material powder (slurry), which is then granulated by a method such as spray drying. Mixing can be done wet or dry, and mixers such as ball mills and vibrating mills can be used. Examples of ceramic powders that can be used as raw materials include silicon carbide, aluminum oxide, aluminum nitride, and silicon nitride.

It is preferable that the ceramic powder be highly pure, preferably at least 96%, and more preferably at least 98%. The average particle size of the ceramic powder varies depending on the type of ceramic powder used as the raw material, but is preferably between 0.1 μm and 1.0 μm, and more preferably between 0.3 μm and 0.8 μm.

It is preferable to use Mo or W as the material for the electrodes embedded in the ceramic sintered body.

Sintering can be performed using uniaxial hot press firing or atmospheric pressure firing. In uniaxial hot press firing, the granulated powder that will form the substrate is filled into a bottomed carbon mold, and after uniaxial pressing, an electrode cut to the desired shape is placed on top of the compact. The same granulated powder is filled on top of this, and a carbon punch is placed on top to form the electrode. It is then preferably hot press fired at a temperature of 1700°C to 2000°C and a pressure of 1 MPa to 20 MPa for 0.1 to 20 hours.

After firing, the surface of the base that will become the top end of the first pin-shaped protrusion is processed, multiple pin-shaped protrusions are formed, the back surface is processed, terminal holes are formed, and the base is ground and polished to the desired shape. To form the pin-shaped protrusions, first the surface of the base that will become the top end of the first pin-shaped protrusion is processed, then the first pin-shaped protrusion is formed, and then the second pin-shaped protrusion is formed.

The surface that forms the upper end of the first pin-shaped protrusion of the base is machined so that the cross-sectional curve cut along a cross section passing through the central axis is approximately symmetrical with respect to the central axis, with the Z value reaching a maximum near the central axis and monotonically decreasing toward the outer edge of the base. In this case, it is preferable that the surface be machined so that ΔH is 5 μm to 50 μm, and more preferably 10 μm to 20 μm. One method for forming the upper surface of the base is to form a curved surface by lapping after grinding the surface, but it can also be formed by MC machining.

Next, the curved shape of the surface that will become the upper end of the first pin-shaped protrusion of the base is measured using a three-dimensional measuring device. If the measurement shows that the curved shape is the specified convex shape that is approximately symmetrical about the central axis, formation of the upper surface of the base is terminated. The upper surface of the base is polished or ground so that the curved shape is the specified convex shape that is approximately symmetrical about the central axis. It is then confirmed that the curved shape of the surface that will become the upper end of the first pin-shaped protrusion of the base after polishing or grinding is the specified convex shape. By repeating these steps, the curved shape is machined into the desired shape. A curved shape that is the specified convex shape that is approximately symmetrical about the central axis means that any cross-sectional curve of the measured curved shape has a maximum Z value near the central axis and monotonically decreases toward the outer edge of the base.

The first pin-shaped protrusions are formed by forming recesses so that the distance from the upper surface to the upper end of the substrate is approximately the same. The second pin-shaped protrusions 32 are also processed in the same manner as the first pin-shaped protrusions 31. After the formation of the first pin-shaped protrusions is complete, all pin-shaped protrusions have approximately the same height, as shown in Figure 10. That is, multiple pin-shaped protrusions are formed by digging to the same depth from the surface that will become the upper end of the first pin-shaped protrusions. The bottom surface formed by the digging becomes the upper surface of the substrate. The first pin-shaped protrusions can be formed by blasting, milling, laser processing, etc. The processing depth GB is preferably 5 μm to 300 μm, and more preferably 50 μm to 200 μm. The curved surface shape of the processed first pin-shaped protrusions can be confirmed as the desired curved surface shape by adsorbing a substrate placed on the first pin-shaped protrusions and measuring the surface opposite the adsorption surface using a laser interferometer. If the curved surface deviates from the desired shape, correction processing is performed to obtain the desired curved surface shape.

Next, the pin-shaped protrusions 30 located in the ring-shaped region RA are processed into second pin-shaped protrusions 32 so that they are lower in height than the first pin-shaped protrusions. The ring-shaped region RA is determined based on temperature distribution measurements, simulations, etc. The second pin-shaped protrusions can be formed by MC processing, etc. In this case, when the difference in height between the first pin-shaped protrusions 31 and the height of the shortest second pin-shaped protrusion is ΔG and the difference in vertical direction between the upper end of the first pin-shaped protrusion closest to the center 16 of the base 10 and the upper end of the first pin-shaped protrusion 31 closest to the outer edge 18 of the base 10 is ΔH, it is preferable that the second pin-shaped protrusions are formed so that ΔH > ΔG ≧ 0.5 × ΔH is satisfied.

If necessary, ventilation holes, annular protrusions, etc. may be formed. This allows for the preparation of a ceramic substrate with an electrode embedded inside and multiple pin-shaped protrusions formed on one main surface.

Finally, connect the terminal to the terminal hole using solder or similar material. The terminal can be made of Ni or similar material. The solder can also be made of Au or similar material.

By doing this, it is possible to manufacture an electrode-embedded member according to an embodiment of the present invention.

[Method of manufacturing substrate holding member]
The ceramic powder is granulated to form a ceramic molded body that will become the support member after firing. The ceramic powder preferably has the same main component as the ceramic powder used in the electrode-embedded member.

Next, the ceramic compact is degreased at a predetermined temperature or higher for a predetermined time or longer to produce a ceramic degreased body. For example, it is heat-treated at a temperature of 400°C or higher and 800°C or lower to produce a ceramic degreased body. The degreasing time is preferably 1 hour or higher and 120 hours or lower. An atmospheric furnace or a nitrogen atmosphere furnace can be used for degreasing, but an atmospheric furnace is preferred.

Next, the ceramic degreased body is fired to form a support member that supports the electrode-embedded member. The support member is preferably fired at atmospheric pressure. The firing temperature is preferably 1500°C or higher and 2000°C or lower. The firing time is preferably 1 hour or higher and 12 hours or lower. The firing atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere.

Then, a support member is placed at a predetermined position on the underside of the electrode-embedded member, and the electrode-embedded member and support member are bonded by applying pressure perpendicular to the bonding surface while heating. The pressure is preferably 1 MPa or more. The heating temperature is preferably 1500°C or more and 2000°C or less. The heating time is preferably 0.5 hours or more and 5 hours or less. The heating atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. This results in a solid-state bond between the substrate holding member body and the support member. Note that the bonding method is not limited to solid-state bonding, and may also be a method involving the interposition of an inorganic bonding material.

It is preferable to perform the processing of the upper surface of the base of the electrode-embedded member, the formation of the pin-shaped protrusions, the polishing and grinding of the pin-shaped protrusions, and the brazing of the terminals after the electrode-embedded member and the support member are joined.

By doing this, it is possible to manufacture a substrate holding member according to an embodiment of the present invention in which an electrode-embedded member and a support member are joined.

[Examples and Comparative Examples]
Example 1
Example 1 is a substrate holding member having a convex curved mounting surface as shown in FIG. 1. The base and support member were made of a sintered body primarily composed of aluminum nitride (AlN). The electrode shape was a shape including multiple circumferential patterns as shown in FIG. 2. A base (electrode-embedded member) and support member were prepared, each with an approximately disk-shaped electrode embedded therein, measuring φ320 mm in diameter and t20 mm in thickness. After bonding to the support member, the top surface of the base was polished to form a convex curved surface. Starting from the outer edge of the base, the top surface was polished using free abrasive grains. The top surface of the base was processed so that the cross-sectional curve cut along the central axis was approximately symmetrical with respect to the central axis and monotonically decreasing toward the outer edge of the base. The top surface of the base was also formed to have a ΔH of 20 μm.

Next, the substrate was ground using a blasting process to form first pin-shaped protrusions. The first pin-shaped protrusions were formed concentrically in an area within φ300 mm from the center of the substrate, with a diameter of φ1 mm and a height of 150 μm from the top surface of the substrate. The surface roughness Ra of the first pin-shaped protrusions was set to 0.4 μm.

In other words, the substrate holding member of Example 1 is a substrate holding member that has been processed so that the cross-sectional curve obtained by cutting the curved mounting surface formed by the upper ends of the first pin-shaped convex portions at a cross section passing through the Z axis, with the central axis of the base being the Z axis, is a curve that has a maximum Z value near the central axis and monotonically decreases toward the outer edge of the base, when the intersection between the cross section and a predetermined reference plane is the X axis.

Next, second pin-shaped protrusions were formed by MC processing on multiple pin-shaped protrusions arranged in the ring-shaped region RA. At this time, processing was performed so that ΔG was 12 μm and the surface roughness Ra of the second pin-shaped protrusions was 1.0. The ring-shaped region RA was an area with a radius of 33 mm or more and 52 mm or less from the center of the base.

Example 2
A substrate holding member was produced under the same conditions as in Example 1, except that ΔH was set to 15 μm and ΔG was set to 5 μm.

Example 3
A substrate holding member was produced under the same conditions as in Example 1, except that ΔH was set to 50 μm and ΔG was set to 25 μm.

Example 4
A substrate holding member was produced under the same conditions as in Example 1, except that ΔH was set to 5 μm and ΔG was set to 3 μm.

Example 5
A substrate holding member was produced under the same conditions as in Example 1, except that ΔH was set to 3 μm and ΔG was set to 1 μm.

(Comparative Example 1)
A substrate holding member was produced under the same conditions as in Example 1, except that the second pin-shaped convex portions were not formed.

(Method for measuring the curved surface)
A substrate (silicon wafer) with a diameter of 300 mm, a thickness of 0.775 mm, and a surface coated with a 30 μm blackbody (a commercially available spray with an emissivity of 92%) was placed on the substrate holder obtained in each Example and Comparative Example, and the surface opposite the curved surface on which it was placed (the surface of the substrate) was measured with a laser interferometer. At this time, the presence or absence of an inflection point outside the ring-shaped region was confirmed.

Next, using the values measured by the laser interferometer, an approximation formula was calculated by quadratically approximating the cross-sectional curves of Example 1 and Comparative Example 1 when the unit of Z was μm and the units of X and Y were mm. Then, the quadratic coefficient of the approximate quadratic curve and the coefficient of determination ^R2 were calculated.

(Evaluation method)
The substrate was placed on the substrate holding member of Example 1 and Comparative Example 1, and a voltage was applied to the internal electrode, setting the temperature of the center of the substrate to 400°C and controlling the temperature. At this time, an infrared camera installed above the substrate was used to measure the temperature distribution of the substrate. The temperature difference ΔT was determined by subtracting the minimum temperature from the maximum temperature in a φ290 mm region excluding 5 mm from the outer edge of the substrate. A temperature difference ΔT of 5.0°C or less was considered good (◯), and a temperature difference ΔT of more than 5.0°C and less than 7.0°C was considered good (△) and evaluated as passing. A temperature difference ΔT greater than this was considered bad (×) and evaluated as failing.

(Evaluation results)
Table 1 shows the results of various measurements in each example and comparative example. "Evaluation" indicates the results of evaluating the temperature difference ΔT according to the above-mentioned evaluation criteria.

In Examples 1 to 5, the temperature difference ΔT was 7.0°C or less, demonstrating a generally uniform temperature distribution. Furthermore, the temperature difference in the radial direction of the ring-shaped area RA was able to be sufficiently low. This suggests that it may be possible to create a predetermined temperature gradient in the radial direction depending on the design of the pin-shaped protrusions, etc.

In Example 5, where ΔH and ΔG did not satisfy the condition ΔH > ΔG ≥ 0.5 x ΔH, the temperature difference ΔT did not satisfy the condition of 5.0°C or less, but it did satisfy the condition of greater than 5.0°C and less than 7.0°C, indicating that a fairly uniform temperature distribution was exhibited. Furthermore, in Example 5, the ΔH value was too small, making it difficult to process the cross-sectional curve without creating an inflection point.

On the other hand, in Comparative Example 1, in which no second pin-shaped protrusions were formed, the condition that the temperature difference ΔT be 5.0°C or less was not met. This is thought to be because the second pin-shaped protrusions were not formed in the ring-shaped region, and the influence of the heater pattern appeared on the substrate.

From the above, it has been confirmed that the electrode-embedding member and substrate-holding member of the present invention can achieve uniform local temperature distribution in the radial direction of the substrate.

The present invention is not limited to the above-described embodiments, and naturally includes various modifications and equivalents that fall within the spirit and scope of the present invention. Furthermore, the structure, shape, number, position, size, etc. of the components shown in each drawing are for convenience of explanation and may be changed as appropriate.

10 Base 12 Upper surface 14 Lower surface 16 Center of base 18 Outer edge 20 Electrode 30 Pin-shaped protrusion 31 First pin-shaped protrusion 31a Upper end of first pin-shaped protrusion 32 Second pin-shaped protrusion 32a Upper end of second pin-shaped protrusion 35 Annular protrusion 42 Cross-sectional curve 50 Terminal 52 Terminal hole 100 Electrode embedding member 110 Support member 112 Bonding surface 150 Substrate holding member 160 Ceramic heater 170 Electrostatic chuck 175 Electrostatic attraction electrode W Substrate

Claims (5)

An electrode-embedding member,
a substrate formed into a disk shape by a ceramic sintered body;
a heater electrode embedded in the base for heating the substrate ;
a plurality of pin-shaped protrusions formed to protrude upward from the upper surface of the base,
the upper surface of the base body is formed as a curved surface that is convex toward the center,
the plurality of pin-shaped protrusions include first pin-shaped protrusions having substantially the same height from the upper surface to an upper end, and second pin-shaped protrusions having a height from the upper surface to an upper end that is lower than the height of the first pin-shaped protrusions,
an upper end of the first pin-shaped protrusion forms a curved mounting surface on which a substrate is placed;
the second pin-shaped protrusion is formed in a ring-shaped region on the upper surface surrounded by concentric circles centered at the center ,
a difference between the height of the first pin-shaped protrusion and the height of the second pin-shaped protrusion that is the shortest among the second pin-shaped protrusions is defined as ΔG;
When the difference in the vertical direction between the upper end of the first pin-shaped protrusion closest to the center of the base and the upper end of the first pin-shaped protrusion closest to the outer edge of the base is ΔH,
ΔH＞ΔG≧0.5×ΔH
An electrode-embedding member characterized by satisfying the above . 2. The electrode-embedding member according to claim 1, wherein two cross-sectional curves obtained by cutting the curved surface formed by the upper ends of the first pin-shaped convex portions at two cross sections passing through the central axis, the two cross-sectional curves being perpendicular to each other and passing through the central axis, have a coefficient of determination ^R2 of 0.99 or more for an approximation equation when each of the cross-sectional curves is approximated by a quadratic curve. A substrate holding member,
The electrode-embedding member according to claim 1 or 2 ;
a support member bonded to a lower surface of the base body opposite to the upper surface thereof, the support member supporting the electrode-embedded member. A ceramic heater,
A ceramic heater comprising the substrate holding member according to claim 3 . An electrostatic chuck,
A substrate holding member according to claim 3 ,
The electrostatic chuck is characterized in that the substrate holding member further comprises an electrode for electrostatic attraction.