Holding device

Abstract

To provide a holding device that suppresses uneven contact with an object.SOLUTION: A holding device 1 according to the present invention includes a plate-shaped substrate 21 having an upper surface 21a and a lower surface 21b that are substantially orthogonal to the first direction, an annular outer convex portion 22 that protrudes upward from the upper surface 21a of the substrate 21, an annular inner convex portion 23 located on the inner peripheral side of the outer convex portion 22 in the first directional view, which protrudes upward from the upper surface 21a of the substrate 21 at substantially the same height as the outer convex portion 22. a suction port 24 provided so as to open on a surface 21a1 between the outer convex portion 22 and the inner convex portion 23 of the upper surface 21a of the substrate 21 in the first directional view, a vacuum flow path 25 that is provided inside the substrate 21 such that one end is connected to the suction port 24 and the other end opens to the lower surface 21b, and can be evacuated. and a penetration hole 26 penetrating the surface 21a2 on the inner peripheral side of the inner convex portion 23 of the upper surface 21a of the substrate 21, and the lower surface 21b of the substrate 21 in the first directional view.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a retaining device. [Background technology]

[0002] In the manufacturing process of semiconductors, etc., a holding device that holds a wafer by vacuum suction is known. As an example of this type of holding device, as shown in Patent Document 1, a so-called pin chuck type holding device is known in which a plurality of protrusions for supporting a wafer are provided on the surface of a base that vacuum suctions the wafer. In this type of holding device, a plurality of protrusions are provided in a dotted form on the surface of the base, and the wafer is vacuum suctioned to the base with the wafer supported by each protrusion. Note that a heater for heating the vacuum suctioned wafer is provided inside the base of this type of holding device.

[0003] As another holding device, for example, as shown in Patent Document 2, a holding device having a first annular convex portion of different heights provided continuously or intermittently on the outer periphery of the surface of the base and a second annular convex portion located inside the first annular convex portion is known. In this holding device, when the height of the first annular convex portion located outside of the first annular convex portion and the second annular convex portion is relatively high, the wafer is placed on the first annular convex portion. Then, inside the first annular convex portion in this state, the space between the back surface of the wafer and the surface of the base is depressurized. An opening portion connected to a vacuum suction device is provided in the region between the first annular convex portion and the second annular convex portion, and the gas in the space is caused to flow outward from the opening portion. In particular, a gap is formed between the back surface of the wafer and the upper end surface of the second annular convex portion, and the speed at which the gas flows from the inside to the outside of the second annular convex portion is set to be locally high in the gap. In this holding device, a Bernoulli force is generated that attracts the wafer toward the front surface of the base by a local increase in the speed of the gas flowing through the gap, and the wafer is held by utilizing this force. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-50300 A [Patent Document 2] JP 2019-62128 A Summary of the Invention [Problem to be solved by the invention]

[0005] Wafers used in semiconductor manufacturing processes and the like usually have deformations such as warping and waviness. When such a deformed wafer is held by the conventional pin chuck-type holding device described above, there are cases where a portion where the wafer makes strong contact with the convex portion (hereinafter, contact portion) and a portion where the wafer is separated from the convex portion and does not make contact (hereinafter, non-contact portion) are formed. Compared to the non-contact portion, the contact portion allows heat from a heater or the like to be more easily transferred to the wafer via the convex portion, and allows heat to be more easily dissipated from the wafer via the convex portion. When contact portions and non-contact portions are formed on a wafer held by a holding device in this way, there is a risk of large temperature unevenness occurring between them, which has been a problem.

[0006] As shown in Patent Document 2, in a conventional holding device utilizing the Bernoulli force, it is necessary to make the height of the first annular convex portion different from the height of the second annular convex portion, and to form a gap between the rear surface of the wafer and the first annular convex portion, etc., for generating the Bernoulli force. Therefore, Patent Document 2 does not disclose a case in which the height of the first annular convex portion and the height of the second annular convex portion are made the same.

[0007] An object of the present invention is to provide a holding device that suppresses uneven contact with an object. [Means for solving the problem]

[0008] <1> a holding device comprising: a plate-shaped base having upper and lower surfaces that are approximately perpendicular to a first direction; a ring-shaped outer convex portion protruding upward from the upper surface of the base; a ring-shaped inner convex portion protruding upward from the upper surface of the base at approximately the same height as the outer convex portion and located on the inner side of the outer convex portion when viewed in the first direction; a suction port provided in a shape that opens into a surface of the upper surface of the base that is between the outer convex portion and the inner convex portion when viewed in the first direction; a vacuum flow path provided inside the base so as to be connected to the suction port and the other end that opens into the lower surface and is capable of drawing a vacuum; and a through hole that penetrates through a surface of the upper surface of the base that is on the inner side of the inner convex portion when viewed in the first direction and the lower surface of the base.

[0009] <2> The base has an inner region located inside the inner convex portion, and an annular outer region located outside the inner region and extending from the inner convex portion to the outer convex portion, and is provided with a first heater provided inside the inner region or on the underside of the base in the inner region, and a second heater capable of controlling the temperature independently of the first heater and provided inside the outer region or on the underside of the base in the outer region. <1> A holding device as described in

[0010] <3> The suction ports are provided in a plurality, and the vacuum flow paths are provided in a plurality such that one end of each of the vacuum flow paths is connected to the plurality of suction ports, respectively, and the other end sides of the plurality of vacuum flow paths are integrated into one. <1> or <2> A holding device as described in Effect of the Invention

[0011] According to the present invention, it is possible to provide a holding device in which uneven contact with an object is suppressed. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a holding device according to a first embodiment; [Diagram 2] Enlarged view of the area shown in Figure 1 [Diagram 3] FIG. 1 is a top view showing a schematic configuration of a holding device; [Figure 4] FIG. 2 is a longitudinal sectional view showing a schematic configuration of the holding device before an object placed on the outer convex portion and the inner convex portion is vacuum-adsorbed; [Diagram 5] FIG. 13 is a longitudinal sectional view showing a schematic configuration of a holding device in a state in which an object placed on an outer convex portion and an inner convex portion is vacuum-adsorbed; [Figure 6] FIG. 1 is a top view showing a schematic diagram of an object being heated while being held in a holding device; [Figure 7] FIG. 11 is a vertical cross-sectional view showing a schematic configuration of a holding device according to a second embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Embodiment 1> Hereinafter, a holding device 1 according to a first embodiment of the present invention will be described with reference to Figs. 1 to 6. Fig. 1 is a vertical cross-sectional view showing a schematic configuration of the holding device 1 of the first embodiment, Fig. 2 is an enlarged view of a range M shown in Fig. 1, and Fig. 3 is a top view showing a schematic configuration of the holding device 1. Each figure shows mutually orthogonal XYZ axes for specifying a direction. For example, the up-down direction in Fig. 1 corresponds to the Z-axis direction. In this specification, the Z-axis direction is referred to as a "first direction". For convenience of explanation, the positive Z-axis direction may be referred to as an upward direction, and the negative Z-axis direction may be referred to as a downward direction.

[0014] The holding device 1 is a device that holds an object (e.g., a semiconductor wafer) W by vacuum suction while heating it to a predetermined processing temperature (e.g., about 200°C or higher and 700°C or lower). The holding device 1 is used as a part of a semiconductor manufacturing device such as a film forming device (CVD film forming device, sputtering film forming device, etc.) or an etching device (plasma etching device, etc.). Such a holding device 1 includes a main body 2 and a columnar support 3. Note that the holding device 1 of this embodiment is not provided with a chuck electrode that generates an electrostatic attraction force.

[0015] The main body 2 is a part that holds and heats the object W, and has a generally disk-like external shape. Such main body 2 mainly includes a base 21, an outer convex portion 22, an inner convex portion 23, a suction port 24, a vacuum flow path 25, a through hole 26, and a heater 27.

[0016] The base 21 has a disk-shaped plate shape when viewed in a first direction, and includes an upper surface 21a and a lower surface 21b that are substantially perpendicular to the first direction (Z-axis direction). The base 21 is formed of ceramics containing aluminum nitride (AlN) or alumina (Al2O3) as a main component, for example. In this specification, the main component means the component with the largest content (mass percentage).

[0017] The diameter of the base 21 is, for example, not less than 200 mm and not more than 450 mm, and the thickness of the base 21 is, for example, not less than 5 mm and not more than 30 mm.

[0018] The outer convex portion 22 and the inner convex portion 23 are portions on which the peripheral edge of the target object W is placed when the target object W is vacuum-adsorbed. The outer convex portion 22 protrudes upward from the upper surface 21a of the base body 21 and has a circular ring shape (an example of a ring shape) when viewed in the first direction. Such an outer convex portion 22 has a shape that protrudes in a convex manner from the upper surface 21a.

[0019] The inner convex portion 23 protrudes upward from the upper surface 21a of the base 21 at approximately the same height as the outer convex portion 22, and forms a circular ring shape (one example of a ring shape) located on the inner circumferential side of the outer convex portion 22 when viewed in the first direction. The inner convex portion 23, like the outer convex portion 22, has a shape that protrudes in a convex manner from the upper surface 21a. The outer convex portion 22 and the inner convex portion 23 are formed integrally with the base 21, and are made of the same ceramic as the base 21.

[0020] The outer convex portion 22 is made of a wall having a predetermined thickness and its upper surface 22a is in the shape of a ring having a substantially constant line width. The inner convex portion 23 is made of a wall having a predetermined thickness and a size smaller than the outer convex portion 22, and its upper surface 23a is in the shape of a ring having substantially the same line width as the upper surface 22a of the outer convex portion 22. The outer convex portion 22 and the inner convex portion 23 are concentrically arranged on the upper surface 21a of the base body 21. The respective central positions of the outer convex portion 22 and the inner convex portion 23 are set at the central position O of the circular upper surface 21a. FIG. 1 shows a virtual axis AX extending in the Z-axis direction (first direction) passing through the central position O of the upper surface 21a of the base body 21.

[0021] The thickness (line width) of the outer convex portion 22 is set to, for example, 0.2 mm or more and 2.0 mm or less, and the thickness (line width) of the inner convex portion 23 is set to, for example, 0.2 mm or more and 2.0 mm or less. The thickness of the outer convex portion 22 and the thickness of the inner convex portion 23 may be the same as or different from each other.

[0022] The upper surface 21a of the base 21 is a substantially flat surface along the X-axis and Y-axis (ZY plane), and the height from such upper surface 21a to the upper surface 22a of the outer convex portion 22 (i.e., the height of the outer convex portion 22) and the height from the upper surface 21a to the upper surface 23a of the inner convex portion 23 (i.e., the height of the inner convex portion 23) are set to be the same (substantially the same) as each other.

[0023] The heights of the outer convex portion 22 and the inner convex portion 23 are the same (approximately the same) and are not particularly limited as long as they do not impair the object of the present invention, but are preferably set to, for example, 0.02 mm or more and 1.0 mm or less. When the heights of the outer convex portion 22 and the inner convex portion 23 are in such a range, the outer convex portion 22 and the inner convex portion 23 can be used to reliably hold the object W by vacuum suction.

[0024] In this specification, whether the height of the outer convex portion 22 and the height of the inner convex portion 23 are substantially the same height can be determined by the following method. First, the outer convex portion 22 and the inner convex portion 23 are cut into four equal parts when viewed in a first direction. In this case, the outer convex portion 22 and the inner convex portion 23 are cut by two planes that pass through the axis AX extending in the first direction and are perpendicular to each other. From the four cut surfaces of the obtained outer convex portion 22, the average height of the upper end of the outer convex portion 22 is obtained, and from the four cut surfaces of the inner convex portion 23, the average height of the upper end of the inner convex portion 23 is obtained. When the difference between the average height of the upper end of the outer convex portion 22 and the average height of the upper end of the inner convex portion 23 is less than 0.5 μm, it is determined that the height of the outer convex portion 22 and the height of the inner convex portion 23 are substantially the same height.

[0025] Between the outer convex portion 22 and the inner convex portion 23, an annular space (gap) S1 is formed that is annular (circular) when viewed in the first direction. The annular space S1 is formed between the inner peripheral surface 22c of the outer convex portion 22 and the outer peripheral surface 23b of the inner convex portion 23. In addition, the annular surface between the outer convex portion 22 and the inner convex portion 23 on the upper surface 21a of the base body 21 may be particularly referred to as the "annular surface 21a1". The annular space S1 is surrounded by the inner peripheral surface 22c of the outer convex portion 22, the outer peripheral surface 23b of the inner convex portion 23, and the annular surface 21a1. Before the object W is placed on the annular space S1, the upper side (i.e., the upper side between the outer convex portion 22 and the inner convex portion 23) is open.

[0026] The outer peripheral surface 22b of the outer convex portion 22 faces outward, and the outer peripheral edge portion 21c of the base body 21 is disposed further outward than the outer peripheral surface 22b. That is, in the case of this embodiment, the outer convex portion 22 is disposed not at the outermost end (outer peripheral edge portion 21c) of the base body 21, but inside it. The inner peripheral surface 22c of the outer convex portion 22 faces the outer peripheral surface 23b of the inner convex portion 23 with the annular space S1 therebetween. Inside the inner convex portion 23, there is a space (inner space) S2, and the inner peripheral surface 23c of the inner convex portion 23 is disposed so as to surround the periphery of the space S2. In the case of this embodiment, of the upper surface 21a of the base body 21, the upper surface 21a on the inside of the inner convex portion 23 may be particularly referred to as the inner upper surface 21a2. The inner upper surface 21a2 is flat (approximately flat), and does not have a convexly raised portion or the like formed thereon.

[0027] It is preferable that a relationship such as 0.8≦r / R≦0.9 holds between the length R from the center position O on the upper surface 21a of the base 21 to the outer peripheral edge portion 21c of the base 21 and the length r from the center position O to the inner peripheral surface 23c of the inner convex portion 23.

[0028] The suction port 24 is provided in a form that opens on a surface (that is, the annular surface 21a1) between the outer convex portion 22 and the inner convex portion 23 of the upper surface 21a of the base body 21 when viewed in the first direction. The suction port 24 is circular when viewed in the first direction, and is set to a size that fits between the outer convex portion 22 and the inner convex portion 23. In other embodiments, the suction port may have other shapes, such as an ellipse or an oval shape, when viewed in the first direction. A plurality of suction ports 24 are provided on the annular surface 21a1, and the suction ports 24 are provided on the annular surface 21a1 so as to be arranged in a line in a ring shape while maintaining an interval (equal interval) between each other. In other words, the plurality of suction ports 24 are evenly arranged in the circumferential direction of the annular surface 21a1. The suction port 24 is connected to one end of a vacuum flow path 25 described later.

[0029] The vacuum flow passage 25 is a flow passage provided inside the base 21 in order to evacuate the inside of the annular space S1. The vacuum flow passage 25 evacuates so that negative pressure is created inside the annular space S1 when the object W is placed on the outer convex portion 22 and the inner convex portion 23 (see Figs. 4 and 5). One end of the vacuum flow passage 25 is connected to the suction port 24. There are multiple vacuum flow passages 25, and one vacuum flow passage 25 is assigned to one suction port 24. In this embodiment, there are five suction ports 24, and five vacuum flow passages 25 are provided inside the base 21 to connect to them.

[0030] 3, the five vacuum channels 25 are arranged so as to converge from each suction port 24 toward one central position O. In other words, the other ends of the vacuum channels 25, which are opposite the suction port 24, are converged into one channel. In this manner, by consolidating the multiple vacuum channels 25 into one, the annular space S1 can be efficiently evacuated to a negative pressure. The other ends of the vacuum channels 25 are arranged so as to open to the lower surface 21b of the base 21.

[0031] The vacuum flow path 25 includes a first flow path 25a extending downward from the suction port 24, a second flow path 25b extending in a direction perpendicular to the first direction while connected to the first flow path 25a, and a third flow path 25c extending in the first direction while connected to the second flow path 25b. The third flow path 25c is shared by the multiple vacuum flow paths 25, and the second flow paths 25b of the multiple vacuum flow paths 25 are connected to one third flow path 25c at the other end side.

[0032] The other end of the vacuum flow path 25 is connected to a vacuum flow path 32 in the columnar support 3, which will be described later. Such a vacuum flow path 25 is connected to an externally disposed vacuum pump (not shown) via the vacuum flow path 32 in the columnar support 3. When this vacuum pump is operated, air (gas) in the annular space S1 is sucked out from the suction port 24, and the sucked air passes through the vacuum flow path 25, etc., and is finally discharged to the outside.

[0033] The through-hole 26 is provided so as to penetrate the base 21 in the thickness direction (Z-axis direction). Such a through-hole 26 is provided so as to penetrate through a surface 21a2 (i.e., the inner upper surface 21a2) on the inner peripheral side of the inner convex portion 23 of the upper surface 21a of the base 21 and a lower surface 21b of the base 21, when viewed in the first direction.

[0034] The through holes 26 in this embodiment are holes for passing lift pins (not shown) when the lift pins are used to lift the object W placed on the outer convex portion 22 and the inner convex portion 23. A plurality of through holes 26 are provided in the base 21. These through holes 26 have the function of communicating the space S2 inside the inner convex portion 23 (the internal space formed when the wafer is sucked) with the external space outside the lower surface 21b of the base 21.

[0035] In addition, a plurality of heaters 27 for heating the base 21 and the like are provided inside the base 21. Each heater 27 has a resistance heating element as a heater electrode. The resistance heating element is mainly composed of, for example, tungsten, molybdenum, an alloy thereof, or a carbide thereof. As such a resistance heating element, for example, a metallization formed by sintering a conductor layer printed with a conductor paste may be used. Each heater 27 forms a linear pattern extending substantially concentrically when viewed in the first direction, and they are arranged on the same virtual plane within the base 21.

[0036] The base 21 is divided into two regions from the viewpoint of heating by the heater 27, etc. One is an inner region H1 located inside the inner convex portion 23 of the base 21, and the other is an annular outer region H2 located outside the inner region H1 and extending from the inner convex portion 23 to the outer convex portion 22.

[0037] The heater 27 in this embodiment is divided into a first heater 271 for mainly heating the inner region H1 and a second heater 272 for mainly heating the outer region H2. The first heater 271 and the second heater 272 are configured so that their temperatures can be adjusted independently of each other. In this embodiment, the first heater 271 is provided inside the inner region H1, and the second heater 272 is provided inside the outer region H2.

[0038] The first heater 271 is made up of a plurality of resistor heating elements, each of which is arranged in a linear pattern extending concentrically in the inner region H1. A predetermined voltage is supplied to each of the first heaters 271 from a predetermined power supply device (not shown) installed externally. In this embodiment, the first heater 271 is arranged above the vacuum flow path 25 (second flow path 25b).

[0039] The second heater 272 is also made up of a plurality of resistor heating elements, each of which is arranged in a linear pattern extending concentrically in the outer region H2. A predetermined voltage is supplied to each second heater 272 from a predetermined external power supply device (not shown). The second heater 272 is appropriately arranged so as not to overlap with the vacuum flow path 25 (first flow path 25a) when viewed in the first direction.

[0040] The outer region H2 is provided with an outer convex portion 22 and an inner convex portion 23 that come into contact with the object W when heated. Therefore, heat from the heater 27 is easily transferred to the object W through the outer convex portion 22 and the inner convex portion 23. In contrast, the inner region H1 does not have a structure that directly contacts the object W when heated, so heat from the heater is relatively less easily transferred to the object W than the outer region H2. In this way, the presence or absence of the outer convex portion 22 and the inner convex portion 23 causes a difference in the ease of heat transfer to the object W, so the first heater 271 arranged in the inner region H1 and the second heater 272 arranged in the outer region H2 are configured so that the applied voltages can be controlled independently of each other. For example, appropriate voltages are applied to the first heater 271 and the second heater 272 so that the second heater 272 generates less heat than the first heater 271.

[0041] The inner region H1 may be further divided into a plurality of regions, and the first heater 271 may be appropriately arranged for each divided region, so that the voltage applied to each region may be controlled independently. Similarly, the outer region H2 may be further divided into a plurality of regions, and the second heater 272 may be appropriately arranged for each divided region, so that the voltage applied to each region may be controlled independently.

[0042] The columnar support 3 is a substantially cylindrical member extending in the Z-axis direction (first direction). Like the base 21 of the main body 2, the columnar support 3 is formed of ceramics mainly composed of aluminum nitride or alumina. The outer diameter of the columnar support 3 is smaller than that of the main body 2, and may be set to, for example, 40 mm or more and 90 mm or less. The height (length in the vertical direction) of the columnar support 3 is not particularly limited as long as it does not impair the object of the present invention, and may be set to, for example, 100 mm or more and 200 mm or less.

[0043] The columnar support 3 and the main body 2 are disposed so that the upper surface 3a of the columnar support 3 and the lower surface 21b of the main body 2 (base 21) face each other in the vertical direction. The columnar support 3 is bonded to the vicinity of the center of the lower surface 21b of the main body 2 (base 21) via a known bonding material (not shown).

[0044] A vacuum flow path 32 consisting of a hole extending in the vertical direction is provided inside the columnar support 3. In addition to the vacuum flow path 32, various terminals (not shown) for supplying power to the heater 27 and the like are provided inside the columnar support 3.

[0045] Next, the operation of the holding device 1 to hold and heat the object W will be described with reference to Figs. 4 to 6. Fig. 4 is a vertical cross-sectional view that shows a schematic configuration of the holding device 1 before the object W placed on the outer convex portion 22 and the inner convex portion 23 is vacuum-adsorbed. The ideal shape of the object (e.g., a semiconductor wafer made of silicon) is a flat plate (disk), but the object W actually used usually has deformations such as warping and undulations. Therefore, the upper surface Wa and lower surface Wb of the object W are usually not flat but distorted.

[0046] When the object W is held by the holding device 1, the object W is placed on the holding device 1 so that the peripheral portion W1 overlaps with the outer convex portion 22 and the inner convex portion 23 when viewed in the first direction, as shown in FIG. 4. At that time, the lower surface Wb of the peripheral portion W1 of the object W faces the upper surface 22a of the outer convex portion 22 and the upper surface 23a of the inner convex portion 23. However, as described above, since the object W is deformed, the lower surface Wb of the peripheral portion W1 of the object W has a portion that is in close contact with the upper surface 22a and the upper surface 23a of the outer convex portion 22 and the upper surface 23a of the inner convex portion 23, and a portion that is lifted away from the upper surface 22a of the outer convex portion 22 and the upper surface 23a of the inner convex portion 23. In this way, before the object W is vacuum-adsorbed, a portion of the peripheral portion W1 is lifted.

[0047] FIG. 5 is a vertical cross-sectional view showing a schematic configuration of the holding device 1 in a state in which the object W placed on the outer convex portion 22 and the inner convex portion 23 is vacuum-adsorbed. After the object W is placed on the outer convex portion 22 and the inner convex portion 23, a vacuum pump (vacuum suction device) is operated to suck out the air (gas) in the annular space S1 between the outer convex portion 22 and the inner convex portion 23 from the suction port 24, and the sucked air is discharged to the outside through the vacuum flow path 25 in the base body 21. When the air in the annular space S1 is discharged to the outside in this manner, the inside of the annular space S1 becomes negative pressure, and the entire lower surface Wb in the peripheral portion W1 of the object W is adsorbed (i.e., vacuum-adsorbed) to the upper surface 22a of the outer convex portion 22 and the upper surface 23a of the inner convex portion 23. Note that the holding device 1 of this embodiment does not hold the object W by using Bernoulli force as in the conventional product.

[0048] Inside the inner convex portion 23, there is a space (internal space) S2 surrounded by the inner peripheral surface 23c of the inner convex portion 23, the inner upper surface 21a2, and the lower surface Wb of the object W. When the air in the annular space S1 is sucked out from the suction port 24, if the air in the space S2 is sucked into the annular space S1 through a very small gap between the upper surface 23a of the inner convex portion 23 and the lower surface Wb of the object W, causing a negative pressure in the space S2, the central portion W2 of the object W is drawn toward the inner upper surface 21a2 and bent so as to approach it. When the object W bends in this way, a force acts on the peripheral portion W1 of the object W to lift it away from the upper surface 22a of the outer convex portion 22 and the upper surface 23a of the inner convex portion 23, and the negative pressure in the annular space S1 may be weakened, thereby weakening the force holding the object W. However, in the holding device 1 of this embodiment, a through hole 26 connecting the inside of the space S2 with the outside of the holding device 1 is provided in the base 21, so that the pressure in the space S2 does not become negative and is greater than the pressure in the annular space S1, thereby preventing the object W from bending as described above.

[0049] The pressure in the space S2 is approximately the same as the pressure outside the holding device 1 (for example, atmospheric pressure). When the object W is vacuum-adsorbed while placed on the outer convex portion 22 and the inner convex portion 23, the object W is stretched approximately straight as shown in Fig. 5, and the adhesion between the lower surface Wb at the peripheral portion W1 of the object W and the upper surface 22a of the outer convex portion 22 and the adhesion between the lower surface Wb at the peripheral portion W1 of the object W and the upper surface 23a of the inner convex portion 23 are uniformly ensured. In this way, the holding device 1 that holds the object W by using vacuum adsorption suppresses uneven contact between the object W and the outer convex portion 22 and the inner convex portion 23 that support it.

[0050] When the object W is held by the holding device 1, a predetermined voltage is applied to the resistance heating element of each heater 27 (each first heater 271, each second heater 272), whereby each heater 27 generates heat and the object W is heated to a predetermined temperature. FIG. 6 is a top view that typically illustrates the object W heated while held by the holding device 1. In FIG. 6, the peripheral portion W1 and the central portion W2 of the object W are separated by a virtual circular boundary line L1. The boundary line L1 corresponds to a portion where the object W and the inner circumferential surface 23c of the inner convex portion 23 overlap when viewed in the first direction. Of the object W, the portion inside the boundary line L1 is the central portion W2 that has a circular shape in a plan view, and the portion outside the boundary line L1 is the peripheral portion W1 that has an annular shape in a plan view.

[0051] The central portion W2 is a portion that is not in contact with the outer convex portion 22 or the inner convex portion 23, and is a portion that is heated mainly by the first heater 271 arranged in the inner region H1 of the holding device 1. In contrast, the peripheral portion W1 is a portion that is in contact with the outer convex portion 22 and the inner convex portion 23, and is a portion that is heated mainly by the second heater 272 arranged in the outer region H2.

[0052] In the holding device 1 of this embodiment, at least the central portion W2 of the object W does not come into contact with the main body portion 2 (the outer convex portion 22, the inner convex portion 23, etc.) of the holding device 1, so that there is no uneven contact with the portion supporting the object W. Therefore, among the object W held by the holding device 1, particularly the central portion W2 is in an environment in which it is easy to heat uniformly. In addition, the peripheral portion W1 is the portion that is in contact with the outer convex portion 22 and the inner convex portion 23 for supporting the object W, and is in an environment in which heat is easily transferred from the main body portion 2 side compared to the central portion W2. However, in the holding device 1 of this embodiment, as described above, the second heater 272 for heating the peripheral portion W1 can be operated independently of the first heater 271 for heating the central portion W2. Therefore, in the holding device 1 of this embodiment, the temperature of the peripheral portion W1 and the temperature of the central portion W2 can be easily controlled to be the same by appropriately adjusting the applied voltage of the second heater 272 and the applied voltage of the first heater 271.

[0053] Here, a description will be given of a manufacturing method of the holding device 1. The manufacturing method of the holding device 1 (main body portion 2 and columnar supports 3) is, for example, as follows: First, the main body portion 2 and the columnar supports 3 are fabricated.

[0054] The main body 2 is manufactured, for example, as follows. First, aluminum nitride powder is mixed with yttrium oxide (Y2O3) powder, an acrylic binder, and an appropriate amount of a dispersant and a plasticizer, and an organic solvent is added to the mixture, which is then mixed in a ball mill to prepare a slurry for a green sheet. This slurry for a green sheet is formed into a sheet shape using a casting device, and the formed product is then dried to produce multiple green sheets.

[0055] A metallization paste is prepared by adding conductive powder such as tungsten or molybdenum to a mixture of aluminum nitride powder, an acrylic binder, and an organic solvent, and kneading the mixture. This metallization paste is printed, for example, using a screen printing device, to form unsintered conductor layers that will later become the first heater 271, the second heater 272, etc., on each specific green sheet. Furthermore, holes that will become the suction port 24, grooves that will become the vacuum flow path 25, and holes that will become the through-holes 26 are provided in advance in the green sheets.

[0056] Next, a plurality of these green sheets (e.g., 20 sheets) are thermocompressed and the outer periphery is cut as necessary to produce a green sheet laminate. This green sheet laminate is cut by machining to produce a disk-shaped molded body, which is degreased, and the degreased molded body is fired to produce a fired body. Next, a mask is placed on the planar surface of the obtained fired body to cover the portions corresponding to the outer convex portion 22 and the inner convex portion 23, and the outer convex portion 22 and the inner convex portion 23 are formed by, for example, shot blasting, which projects particles such as ceramics. Thereafter, the surface of this fired body is polished to obtain the main body portion 2.

[0057] The columnar support 3 is produced, for example, by the following method. First, an aluminum nitride powder is mixed with an yttrium oxide powder, a PVA (polyvinyl alcohol) binder, and an appropriate amount of a dispersant and a plasticizer, and an organic solvent is further added to the mixture, which is mixed in a ball mill to obtain a slurry. This slurry is granulated in a spray dryer to produce a raw material powder. Next, the raw material powder is filled into a rubber mold in which a core corresponding to the vacuum flow path 32 is placed, and the raw material powder in the rubber mold is cold isostatically pressed to obtain a molded body. The obtained molded body is degreased, and the degreased molded body is fired to obtain the columnar support 3.

[0058] Next, the main body 2 and the columnar supports 3 are joined. After performing wrapping processing on the back surface 21b of the main body 2 and the upper surface of the columnar supports 3 as necessary, a known bonding agent made of, for example, a mixture of rare earth and an organic solvent in a paste form is uniformly applied to at least one of the back surface 21b of the main body 2 and the upper surface of the columnar supports 3, and the applied material (bonding agent) is degreased. Thereafter, the back surface 21b of the main body 2 and the upper surface of the columnar supports 3 are overlapped and fired to bond the main body 2 and the columnar supports 3. The above-mentioned manufacturing method allows the holding device 1 to be obtained.

[0059] <Embodiment 2> Next, a holding device 1A according to a second embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is a vertical cross-sectional view that shows a schematic configuration of the holding device 1A according to the second embodiment. The holding device 1A according to this embodiment has the same basic configuration as the holding device 1 according to the first embodiment, and includes a main body 2A and a columnar support 3A. However, in the holding device 1A according to this embodiment, the heater 27A is located outside the base 21A of the main body 2A, unlike the first embodiment. More specifically, the heater 27A is provided on the lower surface 21Ab side of the main body 2A.

[0060] The main body 2A includes an outer convex portion 22A and an inner convex portion 23A, similar to the embodiment 1. A vacuum flow path 25A is formed inside the main body 2A, similar to the embodiment 1, and one end of the vacuum flow path 25A is connected to a suction port 24A. A vacuum flow path 32A connected to the vacuum flow path 25A is provided inside the columnar support 3A.

[0061] The heater 27A is made up of a plurality of heaters, and is made up of a plurality of first heaters 271A and a plurality of second heaters 272A, as in the first embodiment. The heater 27A is embedded in a base material layer 270A made of ceramics or the like, and such base material layer 270A is attached to the lower surface 21Ab of the base 21A using a known adhesive or the like. Of such heaters 27A, the first heater 271A is disposed on the lower surface 21Ab1 of the base 21A in the inner region HA1 of the holding device 1A, and the second heater 272A is disposed on the lower surface 21Ab2 of the base 21A in the outer region HA2 of the holding device 1A. Note that the through hole 26A is a hole through which a lift pin is passed, as in the first embodiment, and is provided in a form penetrating the base 21A and the base material layer 270A. As in the holding device 1A of this embodiment, the heater 27A may be disposed on the lower surface 21Ab side of the base 21A.

[0062] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0063] (1) In each of the above embodiments, a hole through which a lift pin is passed is utilized as the through hole. However, the present invention is not limited to this. In other embodiments, a dedicated through hole may be provided in the base to adjust the pressure in the space inside the inner convex portion.

[0064] (2) In each of the above embodiments, the first heater and the second heater are formed side by side on the same plane, but the present invention is not limited to this. In other embodiments, for example, the first heater and the second heater may be formed on a plane at different heights in the first direction (Z-axis direction). [Explanation of symbols]

[0065] 1... Holding device, 2... Main body portion, 21... Substrate, 21a... Upper surface, 21a1... Annular surface, 21a2 Inner upper surface, 21b... Lower surface, 22... Outer convex portion, 23... Inner convex portion, 24... Suction port, 25... Vacuum flow path, 26... Through hole, 27... Heater, 271... First heater, 272... Second heater, 3... Columnar support, S1... Annular space, S2... Space (inner space), H1... Inner region portion, H2... Outer region portion, W... Object, W1... Peripheral portion, W2... Central portion

Claims

1. a plate-shaped base having upper and lower surfaces substantially perpendicular to a first direction; an outer protrusion having an annular shape and protruding upward from an upper surface of the base; an inner convex portion having an annular shape that protrudes upward from an upper surface of the base at substantially the same height as the outer convex portion and is located on an inner circumferential side of the outer convex portion when viewed in the first direction; a suction port provided in a shape opening on a surface of the upper surface of the base body that is between the outer convex portion and the inner convex portion when viewed in the first direction; a vacuum flow path provided inside the base body such that one end of the vacuum flow path is connected to the suction port and capable of drawing a vacuum; a through hole penetrating a surface of the upper surface of the base body on an inner peripheral side of the inner convex portion when viewed in the first direction and a lower surface of the base body, the outer convex portion is disposed on the inside of the outermost end of the base body, the base body has an inner region located inside the inner convex portion, and an annular outer region located outside the inner region and spanning from the inner convex portion to the outer convex portion, a first heater provided inside the inner region or on a lower surface of the base in the inner region; a second heater capable of controlling a temperature independently of the first heater, the second heater being provided inside the outer region or on the lower surface of the base in the outer region.

2. a plurality of the suction ports are provided, and a plurality of the vacuum channels are provided such that one end of each channel is connected to the plurality of suction ports, respectively; The holding device according to claim 1 , wherein the other ends of the plurality of vacuum channels are integrated into one.

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