Sample holder

Abstract

Provided is a sample holder comprising a ceramic body, a base plate, a bonding material, and a porous body. The ceramic body has a first surface that is a sample holding surface, a second surface positioned opposite to the first surface, and a first through-hole penetrating the first surface and the second surface. The base plate has a second through-hole connected to the first through-hole and supports the ceramic body. The bonding material is positioned between the ceramic body and the base plate and bonds the ceramic body and the base plate. At least a portion of the porous body is positioned inside the first through-hole. The ceramic body has a recess on the bonding material and in at least a part of the periphery of the porous body on the second surface.

Description

Sample holder

[0001] The present disclosure relates to a sample holder.

[0002] For example, there has been known a sample holder that is used in semiconductor manufacturing equipment and the like, in which a ceramic body on which a sample such as a wafer is placed and a base plate that supports the ceramic body are bonded together via a bonding material.

[0003] Some such sample holders have a plurality of through holes for supplying a heat transfer gas between the wafer and the ceramic body in order to improve heat transfer between the wafer and the ceramic body (see, for example, Patent Document 1).

[0004] Japanese Unexamined Patent Publication No. 2019-165193

[0005] The sample holder of the present disclosure includes a ceramic body, a base plate, a bonding material, and a porous body. The ceramic body has a first surface that is a sample holding surface, a second surface located opposite to the first surface, and a first through hole penetrating the first surface and the second surface. The base plate has a second through hole connected to the first through hole, and supports the ceramic body. The bonding material is located between the ceramic body and the base plate, and bonds the ceramic body and the base plate. At least a part of the porous body is located inside the first through hole. The ceramic body has a recess on the bonding material and in at least a part of the periphery of the porous body on the second surface.

[0006] Figure 1 is a longitudinal cross-sectional view showing an example of the configuration of a sample holder according to the first embodiment. Figure 2 is an enlarged cross-sectional view showing an example of the configuration around the porous body in the sample holder according to the first embodiment. Figure 3 is a transverse cross-sectional view showing an example of the configuration around the porous body in the sample holder according to the first embodiment. Figure 4 is a schematic cross-sectional view showing the effect of the area around the porous body in a sample holder according to a comparative example when the temperature rises. Figure 5 is a schematic cross-sectional view showing the effect of the area around the porous body in the sample holder according to the first embodiment when the temperature rises. Figure 6 is an enlarged cross-sectional view showing an example of the configuration around the porous body in a sample holder according to the second embodiment. Figure 7 is a schematic cross-sectional view showing the effect of the area around the porous body in a sample holder according to the second embodiment when the temperature rises. Figure 8 is an enlarged cross-sectional view showing an example of the configuration around the porous body in a sample holder according to the third embodiment.

[0007] The embodiments for implementing the sample holder according to this disclosure (hereinafter referred to as "Embodiments") will be described in detail below with reference to the drawings. However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0008] Furthermore, in the embodiments described below, expressions such as "orthogonal" or "parallel" may be used, but these expressions do not require strict "orthogonal" or "parallel" alignment. In other words, each of the above expressions allows for deviations such as manufacturing accuracy and installation accuracy.

[0009] Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X, Y, and Z axis directions are sometimes defined, and a Cartesian coordinate system is shown in which the Z axis direction is the thickness direction of the sample holder.

[0010] (First Embodiment) First, the configuration of the sample holder 1 according to the first embodiment will be described with reference to Figures 1, 2, and 3. Figure 1 is a longitudinal cross-sectional view showing an example of the configuration of the sample holder according to the first embodiment. Figure 2 is an example of the configuration around the porous body 30 in the sample holder 1 according to the first embodiment, and is an enlarged view of the R portion in Figure 1. Figure 3 is a transverse cross-sectional view showing an example of the configuration around the porous body 30 in the sample holder 1 according to the first embodiment.

[0011] As shown in Figures 1 and 2, the sample holder 1 comprises a ceramic body 10, a base plate 20, a porous body 30, and a bonding material 40. The sample holder 1 may also be constructed by bonding a disc-shaped base plate 20 to the underside of a disc-shaped ceramic body 10.

[0012] The sample holder 1 has multiple gas holes arranged in a plan view, penetrating from the first surface 10a of the ceramic body 10, which is the top surface of the sample holder 1, to the fourth surface 20b of the base plate 20, which is the bottom surface of the sample holder 1. Through these gas holes, a gas, such as helium, is supplied from the bottom of the sample holder 1 to the space on the first surface 10a of the ceramic body 10, which is the sample holding surface.

[0013] Specifically, the gas flows through the second through-hole 21, the porous body 30, and the first through-hole 11 in that order, as will be described later. The gas is supplied to improve the uniformity of the heat distribution of the sample. The gas also contributes to improving heat transfer to the ceramic body 10.

[0014] The role of gas in heat transfer will be explained below. If the sample holder 1 is, for example, an electrostatic chuck that holds the sample by electrostatic force, when a wafer is placed on the mounting surface of the upper surface of the ceramic body 10 (described later), the ceramic body 10 and the wafer tend to make point contact. Since the wafer is basically distorted, gaps may form in places between the ceramic body 10 and the wafer.

[0015] In this case, a difference in heat transfer occurs between areas with a gap between the ceramic body 10 and the wafer, i.e., areas where the wafer is separated from the ceramic body 10, and areas without a gap, i.e., areas where the ceramic body 10 and the wafer are in contact. This difference in heat transfer results in temperature unevenness within the wafer surface. Temperature unevenness within the wafer surface reduces the uniformity of temperature within the wafer surface, which affects the wafer processing.

[0016] Therefore, in the electrostatic chuck, numerous protrusions are formed on the mounting surface of the upper surface of the electrostatic chuck, and the wafer is placed on these protrusions. Furthermore, a gas such as helium flows between the wafer and the mounting surface of the upper surface of the electrostatic chuck to improve heat transfer. Gases such as helium have relatively high thermal conductivity. For this reason, the heat from the wafer is transferred to the ceramic body 10 via the gas such as helium.

[0017] Because this type of heat transfer occurs across the entire wafer surface, differences in heat transfer within the wafer surface are less likely to occur, resulting in less temperature unevenness. This improves the uniformity of temperature within the wafer surface.

[0018] The ceramic body 10 described above is made of ceramic. The ceramic body 10 may be formed from a ceramic-containing raw material into a flat plate shape, for example, a disc shape. The ceramic body 10 may be made of, for example, aluminum oxide (Al ２ O ３ (Hereafter, it may be referred to as alumina.) Aluminum nitride (AlN), yttrium oxide (Y ２ O ３ ) may also be included as the main component.

[0019] The ceramic body 10 has a first surface 10a which is a sample holding surface, and a second surface 10b located opposite the first surface 10a. The second surface 10b is the surface that is joined to the base plate 20 via a bonding material 40, which will be described later.

[0020] The ceramic body 10 has a first through-hole 11 that penetrates the first surface 10a and the second surface 10b. This first through-hole 11 constitutes a part of the gas hole in the sample holder 1.

[0021] The sample holder 1 in this embodiment may be, for example, an electrostatic chuck that holds the sample by electrostatic force. In this case, as shown in Figure 1, the sample holder 1 may be equipped with an electrode 13 for electrostatic adsorption inside the ceramic body 10, which is an insulator. The electrode 13 is a thin, flat conductive layer. The electrode 13 may be positioned, for example, parallel to the first surface 10a of the ceramic body 10.

[0022] The electrode 13 may be made of a conductor mainly composed of metals such as molybdenum (Mo), platinum (Pt), or tungsten (W). By applying a voltage to the electrode from the outside, an electrostatic force is generated, which causes the sample to be adsorbed and held. In the example shown in Figure 1, two electrodes 13 are observed, but the number of electrodes 13 is not limited to this.

[0023] As shown in Figures 1 and 2, the base plate 20 is a disc-shaped member that supports the ceramic body 10. The base plate 20 is joined to the second surface 10b of the ceramic body 10 via a bonding material 40. The base plate 20 may be made of a metal such as aluminum.

[0024] The base plate 20 may have a third surface 20a that is joined to the ceramic body 10 via a bonding material 40, which will be described later, and a fourth surface 20b located opposite the third surface 20a.

[0025] The base plate 20 has a second through-hole 21 that penetrates the third surface 20a and the fourth surface 20b. The second through-hole 21 constitutes part of the gas hole in the sample holder 1 described above. The second through-hole 21 is connected to the first through-hole 11 of the ceramic body 10. Here, "connected" means connected in a way that allows gas to flow. In this disclosure, the base plate 20 may also function as a high-frequency electrode to which high-frequency power for plasma generation is applied.

[0026] At least a portion of the porous body 30 is located inside the first through-hole 11 of the ceramic body 10. In the aforementioned gas holes, at least a portion of the porous body 30 may be located near the joint between the ceramic body 10 and the base plate 20.

[0027] The porous body 30 has a porosity sufficient to allow gas to pass through. The porous body 30 may be columnar in shape, for example, a cylinder. The porous body 30 is a gas channel and a component that can suppress the plasma used on the first surface 10a of the ceramic body 10, which is the sample holding surface, from entering through the first through-hole 11 of the ceramic body 10 and flowing downward (in this case, in the negative Z-axis direction). As the material constituting the porous body 30, a ceramic material such as alumina can be used.

[0028] The bonding material 40 is located between the ceramic body 10 and the base plate 20. The bonding material 40 joins the ceramic body 10 and the base plate 20. The bonding material 40 is made by curing an adhesive made of an insulating material. For example, a silicone-based adhesive can be used as such an adhesive.

[0029] As shown in Figure 2, the ceramic body 10 has a recess 12. The recess 12 is located on the bonding material 40 and in at least a portion of the periphery of the porous body 30 on the second surface 10b of the ceramic body 10. The depth L1 of the recess 12 may be greater than the thickness L2 of the bonding material 40.

[0030] Furthermore, the recess 12 may be connected to the second through-hole 21 of the base plate 20. Here, "connected" means that, similar to the relationship between the second through-hole 21 and the first through-hole 11 described above, they are connected in a way that allows gas to flow.

[0031] As shown in Figure 3, the recess 12 may be annular in a planar perspective view taken toward the first surface 10a of the ceramic body 10. In this case, the recess 12 is annular even when the joint surface between the ceramic body 10 and the bonding material 40 is viewed from the base plate 20 side.

[0032] Furthermore, the base plate 20 contains a cooling channel through which a refrigerant flows to suppress the temperature rise of the ceramic body 10 caused by plasma irradiation. This cooling channel is positioned to avoid the area around the first through-hole 11 of the ceramic body 10.

[0033] Next, the action of the bonding material in the sample holder 1 according to the first embodiment when the temperature rises will be explained with reference to Figures 4 and 5. Figure 4 is a schematic cross-sectional view showing the action of the area around the porous body 30 in the sample holder 1A according to a comparative example when the temperature rises. Figure 5 is a schematic cross-sectional view showing the action of the area around the porous body 30 in the sample holder 1 according to the first embodiment when the temperature rises.

[0034] Note that in Figures 4 and 5, for the sake of explanation, the degrees of expansion A1 and A2 of the ceramic body 10 and the bonding material 40 in the horizontal direction (here, the X-axis direction) are shown, but thermal expansion of the ceramic body 10 and the bonding material 40 occurs in all directions.

[0035] The sample holder 1A in the comparative example shown in Figure 4 does not have a recess 12 like the sample holder 1 in the first embodiment described above. In the sample holder 1A shown in Figure 4 and the sample holder 1 shown in Figure 5, as described above, the cooling channel is positioned in the base plate 20 so as to avoid the area around the first through hole 11.

[0036] Therefore, in the ceramic body 10, the cooling performance around the first through-hole 11, which does not have a cooling channel, is smaller than that of other parts with a cooling channel. Consequently, in the sample holder 1A shown in Figure 4 and the sample holder 1 shown in Figure 5, the temperature around the first through-hole 11 becomes higher than that of other parts of the ceramic body 10 when the temperature rises.

[0037] As shown in Figure 4, in the comparative example sample holder 1A, when the temperature rises, the bonding material 40 expands more than the ceramic body 10, resulting in a large difference between the degree of expansion A1 of the ceramic body 10 and the degree of expansion A2 of the bonding material 40. In other words, the difference in thermal expansion between the bonding material 40 and the ceramic body 10 is large. Therefore, when the temperature rises, the difference in thermal expansion between the bonding material 40 and the ceramic body 10 around the first through hole 11 is large, the interfacial stress between the two increases, and there is a risk of delamination of the bonding material 40.

[0038] In contrast, as shown in FIG. 5, in the sample holder 1 according to the first embodiment, when the temperature rises, the expanded portion 40a of the bonding material enters the inside of the recess 12, so the difference between the expansion degree A1 of the ceramic body and the expansion degree A2 of the bonding material 40 is small. That is, the difference in thermal expansion between the bonding material 40 and the ceramic body 10 is small. For this reason, the interfacial stress between the two is reduced, and the occurrence of peeling of the bonding material 40 is reduced.

[0039] As described above, in the sample holder 1 according to the first embodiment, the provision of the recess 12 in at least a part of the periphery of the first through hole 11 allows the expanded portion of the bonding material 40 to enter the inside of the recess 12. That is, even if the bonding material 40 thermally expands, the expanded portion 40a of the bonding material 40 is accommodated in the recess 12. It should be noted that the depiction of the expanded portion 40a in the drawings is for the purpose of showing thermal expansion, and does not necessarily match the dimensional ratio with other members or the like.

[0040] This reduces the interfacial stress between the ceramic body 10 and the bonding material 40. By reducing the interfacial stress between the ceramic body 10 and the bonding material 40, the occurrence of peeling of the bonding material 40 can be reduced. Thereby, the durability of the ceramic body 10 during temperature increase can be improved.

[0041] Furthermore, in the sample holder 1 according to the first embodiment, the recess 12 is annular in planar perspective viewed toward the first surface 10a of the ceramic body 10, whereby the occurrence of peeling of the bonding material 40 can be further reduced over the entire circumference of the first through hole 11 of the ceramic body 10.

[0042] Furthermore, as in the sample holder 1 according to the first embodiment shown in FIG. 2, the depth L1 of the recess 12 may be larger than the thickness L2 of the bonding material. When the depth L1 of the recess 12 is larger than the thickness L2 of the bonding material, the expanded portion of the bonding material 40 is less likely to fill the inside of the recess 12. For this reason, even if the bonding material 40 thermally expands, the expanded portion 40a of the bonding material 40 is accommodated in the recess 12.

[0043] This reduces the interfacial stress between the ceramic body 10 and the bonding material 40. By reducing the interfacial stress between the ceramic body 10 and the bonding material 40, the occurrence of peeling of the bonding material 40 can be reduced. This improves the durability of the ceramic body 10 during temperature increase.

[0044] Further, as in the sample holder 1 according to the first embodiment shown in FIG. 2, the recess 12 may communicate with the second through hole 21. When the recess 12 communicates with the second through hole 21, the recess 12 is not blocked by the bonding material 40, so gas enters the interior of the recess 12. When gas enters the interior of the recess 12, an increase in temperature around the first through hole 11 can be reduced compared to a case where gas does not enter the interior of the recess 12.

[0045] (Second Embodiment) Next, a sample holder 1 according to a second embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is an enlarged cross-sectional view showing an example of the configuration around a porous body in the sample holder 1 according to the second embodiment. FIG. 7 is a schematic cross-sectional view showing the action around the porous body in the sample holder 1 according to the second embodiment during temperature increase.

[0046] In the second embodiment described below, the same portions as those in the first embodiment described above are denoted by the same reference numerals as those in the first embodiment, and description thereof may be omitted.

[0047] As shown in FIG. 6, the sample holder 1 may include an elastic member 50. In this case, the area on the bonding material 40 inside the recess 12 is a void 12a, and the elastic member 50 is positioned on the void 12a inside the recess 12.

[0048] In the sample holder 1 according to the second embodiment, in addition to the same effects as those of the first embodiment described above, arcing resistance can be improved. Specifically, it is empirically known that the sample holder 1 is used in a plasma environment, and arcing occurs if there is a space around the first through hole 11; however, positioning the elastic member 50 inside the recess 12 can improve arcing resistance.

[0049] As shown in Figure 7, in the sample holder 1 according to the second embodiment, when the temperature rises, the expanded portion 40a of the bonding material 40 enters the interior of the recess 12. At this time, the elastic member 50 is pressed by the expanded portion 40a of the bonding material 40 that has entered the interior of the recess 12 and undergoes elastic deformation. The deformed portion 50a of the elastic member 50 escapes into the empty space of the void 12a. In other words, the deformed portion 50a of the elastic member 50 is allowed in the void 12a.

[0050] The elastic member 50 has a lower elastic modulus than the bonding material 40 and is more easily deformed than the bonding material 40. Because the elastic member 50 is more easily deformed than the bonding material 40, even if the elastic member 50 interferes with the thermally expanded bonding material 40, it is less likely to hinder the expansion of the bonding material 40. For example, silicone resin can be used as the elastic member 50.

[0051] (Third Embodiment) Next, the sample holder 1 according to the third embodiment will be described with reference to Figure 8. Figure 8 is an enlarged cross-sectional view showing an example of the configuration around the porous body 30 in the sample holder 1 according to the third embodiment.

[0052] In the third embodiment described below, the same reference numerals as those used in the first and second embodiments are used for parts that are identical to those used in the first and second embodiments, and their descriptions may be omitted.

[0053] As shown in Figure 8, in the ceramic body 10, the outer diameter of the second surface 10b of the recess 12 may widen in a direction away from the porous body 30 (surface direction).

[0054] Here, "outer diameter" refers to the inner surface of the recess 12 that is furthest from the porous body 30, as observed in a cross-section along the axial direction (in this case, the Z-axis direction) of the first through hole 11. In Figure 8, the outer diameter is shown by a thick line. Furthermore, "expanding" refers to the expansion of the inner surface of the recess 12 that is furthest from the porous body 30, relative to a virtual straight line SL that intersects the first surface 10a.

[0055] In the sample holder 1 shown in Figure 8, the outer diameter of the recess 12 widens from the middle of the inner surface away from the porous body 30 in the recess 12, but this is not limited to this configuration. For example, the outer diameter of the recess 12 may widen in a continuous inclination from the top surface 12b on the first surface 10a side of the recess 12 to the second surface 10b.

[0056] In the sample holder 1 according to the third embodiment, in addition to the same effects as those of the first and second embodiments described above, the bonding material 40 can expand in stages, thereby reducing the interfacial stress between the ceramic body 10 and the bonding material 40.

[0057] Specifically, when the bonding material 40 undergoes thermal expansion, this expansion occurs along the inner surface of the recess 12. However, because the outer diameter of the recess 12 expands away from the porous body 30, i.e., it is inclined, the bonding material 40 can expand in stages. This reduces the interfacial stress between the ceramic body 10 and the bonding material 40. The reduced interfacial stress between the ceramic body 10 and the bonding material 40 reduces the occurrence of delamination of the bonding material 40. This improves the durability of the ceramic body 10 when the temperature rises.

[0058] Although the present disclosure has been described in detail above, this disclosure is not limited to the embodiments described above, and various modifications and improvements are possible without departing from the gist of this disclosure.

[0059] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the above embodiments can be embodied in a variety of forms. Furthermore, the above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0060] Furthermore, this technology can also take the following configurations: (1) A sample holder comprising: a ceramic body having a first surface which is a sample holding surface, a second surface located opposite the first surface, and a first through-hole that penetrates the first surface and the second surface; a base plate having a second through-hole connected to the first through-hole and supporting the ceramic body; a bonding material located between the ceramic body and the base plate and joining the ceramic body and the base plate; and a porous body in which at least a part is located inside the first through-hole, wherein the ceramic body has a recess on the bonding material and at least a part around the porous body on the second surface. (2) The sample holder according to (1), wherein the recess is annular in a planar perspective view toward the first surface. (3) The sample holder according to (1) or (2), wherein the depth of the recess is greater than the thickness of the bonding material. (4) The sample holder according to any one of (1) to (3), wherein the space above the joining material inside the recess is a void, and an elastic member is provided on the void. (5) The sample holder according to (2), wherein the outer diameter of the recess on the second surface expands in a direction away from the porous body. (6) The sample holder according to any one of (1) to (5), wherein the recess is connected to the second through hole.

[0061] 1 Sample holder 10 Ceramic body 10a First surface 10b Second surface 11 First through hole 12 Recess 12a Gap 20 Base plate 21 Second through hole 30 Porous body 40 Joining material 50 Elastic member L1 Depth L2 Thickness

Claims

1. A sample holder comprising: a ceramic body having a first surface which is a sample holding surface, a second surface located opposite the first surface, and a first through-hole that penetrates the first surface and the second surface; a base plate having a second through-hole connected to the first through-hole and supporting the ceramic body; a bonding material located between the ceramic body and the base plate and joining the ceramic body and the base plate; and a porous body, at least a portion of which is located inside the first through-hole, wherein the ceramic body has recesses on the bonding material and at least a portion of the periphery of the porous body on the second surface.

2. The sample holder according to claim 1, wherein the recess is annular in a planar perspective view taken toward the first surface.

3. The sample holder according to claim 1 or 2, wherein the depth of the recess is greater than the thickness of the bonding material.

4. The sample holder according to any one of claims 1 to 3, wherein the space above the joining material inside the recess is a void, and an elastic member is provided on the void.

5. The sample holder according to claim 2, wherein the recess has an outer diameter on the second surface that widens in a direction away from the porous body.

6. The sample holder according to any one of claims 1 to 5, wherein the recess is connected to the second through hole.

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