Adhesive substrate

Abstract

This attractive adhesion substrate comprises an insulating base, a conductive layer, and a protruding section. The base has a first surface that retains an item under processing, and a second surface that is located on the opposite side from the first surface. The conductive layer is located in the interior of the base, and extends along the first surface. The protruding section is located in the interior of the base, and protrudes from the conductive layer toward the second surface side. The protruding section has a first end surface that is in contact with the conductive section, and a second end surface that is located on the second surface side. A first distance between the first end surface and the second end surface is greater than 1 / 2 times the thickness of the conductive layer.

Description

Technical Field

[0001] The disclosed embodiments relate to a suction substrate.

Background Art

[0002] An electrostatic chuck for holding a workpiece such as a semiconductor wafer is known. Such an electrostatic chuck includes a suction substrate in which an electrode is located inside an insulating substrate (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

[0004] The suction substrate according to one aspect of the embodiment includes an insulating substrate, a conductive layer, and a protruding portion. The substrate has a first surface for holding a workpiece and a second surface located on the opposite side of the first surface. The conductive layer is located inside the substrate and extends along the first surface. The protruding portion is located inside the substrate and protrudes from the conductive layer toward the second surface side. The protruding portion has a first end face in contact with the conductive layer and a second end face located on the second surface side. The first distance between the first end face and the second end face is greater than 1 / 2 times the thickness of the conductive layer.

Brief Description of the Drawings

[0005] [Figure 1] FIG. 1 is a cross-sectional view showing an example of an electrostatic chuck having a suction substrate according to the first embodiment. [Figure 2] FIG. 2 is an enlarged view of region A shown in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along line B-B shown in FIG. 1. [Figure 4A]Figure 4A is a cross-sectional view showing another example of a protrusion on the adsorption substrate according to the first embodiment. [Figure 4B] Figure 4B is a cross-sectional view showing another example of a protrusion on the adsorption substrate according to the first embodiment. [Figure 5A] Figure 5A is a cross-sectional view showing another example of the adsorption substrate according to the first embodiment. [Figure 5B] Figure 5B is a cross-sectional view showing another example of the adsorption substrate according to the first embodiment. [Figure 5C] Figure 5C is a cross-sectional view showing another example of the adsorption substrate according to the first embodiment. [Figure 6] Figure 6 is a cross-sectional view showing another example of an electrostatic chuck according to the first embodiment. [Figure 7] Figure 7 is a cross-sectional view showing an example of an electrostatic chuck having an adsorption substrate according to the second embodiment. [Figure 8] Figure 8 is an enlarged view of region C shown in Figure 7. [Modes for carrying out the invention]

[0006] In the structure described above, delamination sometimes occurred at the interface between the substrate of the adsorption substrate and the electrode.

[0007] Therefore, there is a need for adsorption substrates that are less prone to delamination.

[0008] The embodiments of the adsorption substrate disclosed herein will be described below with reference to the attached drawings. However, this disclosure is not limited to the embodiments described below.

[0009] <First Embodiment> Figure 1 is a cross-sectional view showing an example of an electrostatic chuck having an adsorption substrate according to the first embodiment. Figure 2 is an enlarged view of region A shown in Figure 1. Figure 3 is a cross-sectional view along line BB shown in Figure 1.

[0010] The electrostatic chuck 1 comprises an adsorption substrate 10, a heat exchanger 20, and a bonding material 30. The electrostatic chuck 1 uses the electrostatic force generated on the surface of the adsorption substrate 10 to adsorb an object to be processed, such as a semiconductor wafer.

[0011] The adsorption substrate 10 has, for example, a substantially disc shape. The adsorption substrate 10 may be a disc shape with a diameter of 50 mm to 400 mm and a thickness of 2 mm to 20 mm. The adsorption substrate 10 has a first surface 10a and a second surface 10b facing each other in the thickness direction. The first surface 10a is a holding surface for holding the object to be processed. The second surface 10b is located on the opposite side of the first surface 10a and may be joined to the heat exchanger 20 using a bonding material 30.

[0012] The adsorption substrate 10 has a base body 11, a conductive layer 12, a protrusion 13, and a conductor 14. The base body 11 is insulating. The base body 11 mainly contains ceramics such as aluminum oxide (Al2O3), aluminum nitride (AlN), or yttria (Y2O3).

[0013] The conductive layer 12 is located inside the substrate 11. The conductive layer 12 extends along the first surface 10a in its vicinity. Also, as shown in Figure 3, the conductive layer 12 is, for example, approximately circular in plan view. The conductive layer 12 can have a diameter of, for example, 30 mm to 398 mm in plan view. Also, as shown in Figure 2, the conductive layer 12 has a thickness t1. The conductive layer 12 mainly contains precious metals (for example, platinum (Pt) or palladium (Pd)).

[0014] Although this disclosure provides an example of a unipolar structure having one conductive layer 12, the conductive layer 12 is not limited to one, and a bipolar structure having two conductive layers 12 may also be provided.

[0015] The protruding portion 13 is located inside the base body 11. The protruding portion 13 is positioned so as to protrude from the conductive layer 12 toward the second surface 10b side. As shown in FIG. 2, the protruding portion 13 has a first end face 131 in contact with the conductive layer 12 and a second end face 132 located on the second surface 10b side. Further, as shown in FIG. 3, a plurality of protruding portions 13 having a substantially circular columnar shape in plan view may be connected to the conductive layer 12. Note that the shape of the protruding portion 13 in plan view is not limited to that shown in FIG. 3, and may be, for example, an elliptical shape or a polygonal shape.

[0016] As shown in FIG. 1, since the protruding portion 13 is positioned so as to fit into the concave base body 11, for example, even when the adsorption substrate 10 receives an external force, the protruding portion 13 is difficult to come off from the base body 11, and thus the conductive layer 12 connected to the protruding portion 13 is difficult to peel off from the base body 11. Accordingly, according to the adsorption substrate 10 according to the present embodiment, delamination is unlikely to occur.

[0017] Further, as shown in FIG. 2, the protruding portion 13 has a first distance d1 between the first end face 131 and the second end face 132. Such a first distance d1 is larger than 1 / 2 times the thickness t1 of the conductive layer 12. Also, the first distance d1 may be larger than a second distance d2 between the first surface 10a and the conductive layer 12. Thus, by the adsorption substrate 10 having the protruding portion 13 whose shape is different from the fine irregularities located on the surface of the conductive layer 12, the occurrence of delamination can be further reduced. Here, the thickness t1 may be, for example, in the range of 2 μm to 20 μm. The first distance d1 may be 1 μm to 3000 μm. The first distance d1 may be 500 μm or more. Also, the second distance d2 can be, for example, 300 μm.

[0018] The material of the protruding portion 13 may be, for example, the same as that of the conductive layer 12. Accordingly, the adsorption substrate 10 can be manufactured without separately preparing the material of the protruding portion 13.

[0019] Furthermore, the material of the protrusion 13 may be different from that of the conductive layer 12. The conductor 14 is connected to the power supply terminal 40 that is brought out to the outside, and power is supplied to the conductive layer 12 via the conductor 14. For this reason, the protrusion 13 may have insulating properties. The protrusion 13 may be made of, for example, a metal material, a carbon material, or a thermosetting resin. The protrusion 13 may be made of a ceramic material different from that of the substrate 11.

[0020] Furthermore, the substrate 11 may contain, for example, a heater or RF (radio frequency) electrodes.

[0021] The heat exchanger 20 receives heat from the adsorption substrate 10 and dissipates it to the outside. The heat exchanger 20 is bonded to the second surface 10b of the adsorption substrate 10 by a bonding material 30 such as silicone. The heat exchanger 20 may have a flow path 21 for flowing a cooling medium. The heat exchanger 20 in this embodiment may be made of a metal such as aluminum, or of a ceramic such as alumina or silicon carbide.

[0022] Furthermore, if the heat exchanger 20 is made of metal, the heat exchanger 20 may be used as the RF electrode of the adsorption substrate 10. Also, if the heat exchanger 20 is made of ceramic, a metal layer may be formed on the outer surface of the heat exchanger 20, and this metal layer may be used as the RF electrode of the electrostatic chuck 1.

[0023] As shown in Figure 2, the adsorption substrate 10 exhibits a protruding portion 13 with a constant cross-sectional shape in the thickness direction, but is not limited to this. Figures 4A to 4B are cross-sectional views showing another example of a protruding portion of the adsorption substrate according to the first embodiment.

[0024] As shown in Figure 4A, the adsorption substrate 10 may have tapered projections 13 whose cross-sectional shape changes so that the cross-sectional area increases from the first end face 131 to the second end face 132.

[0025] Thus, if the protrusion 13 has a tapered shape, even if the adsorption substrate 10 is subjected to an external force, for example, the contact area between the protrusion 13 and the base body 11 increases, making it less likely for the conductive layer 12 connected to the protrusion 13 to peel off from the base body 11. As a result, the adsorption substrate 10 according to this embodiment can further reduce the occurrence of delamination.

[0026] Furthermore, as shown in Figure 4A, the protrusion 13 has a third distance d3, which is the distance between the first end face 131 and the second end face 132. This third distance d3 may be, for example, 1 μm or more. Also, the third distance d3 can be in the range of, for example, 0.5 mm to 3.0 mm. The diameter D1 of the first end face 131 can be, for example, 0.3 mm to 2.5 mm. The diameter D2 of the second end face 132 can be, for example, 0.5 mm to 3.0 mm. Also, the thickness t2 of the conductive layer 12 can be in the range of, for example, 5 μm to 20 μm.

[0027] Furthermore, as shown in Figure 4B, the adsorption substrate 10 may have tapered projections 13 whose cross-sectional shape changes such that the cross-sectional area decreases from the first end face 131 to the second end face 132.

[0028] Thus, if the protrusion 13 has a tapered shape, even if the adsorption substrate 10 is subjected to an external force, for example, the contact area between the protrusion 13 and the base body 11 increases, making it less likely for the conductive layer 12 connected to the protrusion 13 to peel off from the base body 11. As a result, the adsorption substrate 10 according to this embodiment can further reduce the occurrence of delamination.

[0029] Furthermore, as shown in Figure 4B, the projection 13 has a fourth distance d4, which is the distance between the first end face 131 and the second end face 132. This fourth distance d4 may be 1 μm or more. For example, it can be in the range of 0.5 mm to 3.0 mm. Also, the diameter D3 of the first end face 131 can be, for example, 0.5 mm to 3.0 mm. The diameter D4 of the second end face 132 can be, for example, 0.3 mm to 2.5 mm.

[0030] The adsorption substrate 10 according to this embodiment is shown in Figure 3 as an example in which a plurality of protrusions 13 are distributed evenly, but it is not limited to this. Figures 5A to 5C are cross-sectional views showing another example of the adsorption substrate according to the first embodiment.

[0031] As shown in Figure 5A, the adsorption substrate 10 may be positioned such that the protrusions 13 located in the outer peripheral region 122 of the conductive layer 12, when viewed from above, are denser than those in the inner peripheral region 121. This is expected to further reduce delamination compared to the case where multiple protrusions 13 are distributed without density. The inner peripheral region 121 can be, for example, the portion of the conductive layer 12, when viewed from above, that satisfies the condition that diameter L1 ≤ 0.6 × L. The outer peripheral region 122 is the remaining portion of the conductive layer 12, when viewed from above, that is located outside the inner peripheral region 121.

[0032] As shown in Figure 5B, the suction substrate 10 may have cylindrical protrusions 13 that are located concentrically in a plan view.

[0033] Furthermore, as shown in Figure 5C, the adsorption substrate 10 may have protrusions 13 located inward from the contour 12a of the conductive layer 12 in a plan view. This reduces peeling from the contour 12a of the conductive layer 12. In this case, the distance between the contour 12a of the conductive layer 12 and the protrusion 13 adjacent to the contour 12a can be, for example, 10 mm to 20 mm. If the adsorption substrate has through holes through which lift pins for lifting the wafer pass, the conductive layer 12 is arranged to avoid the through holes. In this case, a contour 12a exists in the conductive layer around the through holes, and by setting the distance between the contour 12a and the protrusion 13 adjacent to it to, for example, 10 mm to 20 mm, peeling of the conductive layer 12 from the contour 12a can be reduced. The distance between adjacent protrusions 13 can be, for example, 20 mm. If the adsorption substrate 10 has multiple conductive layers 12, the arrangement of the protrusions 13 can be determined for each of the multiple conductive layers 12.

[0034] Figure 6 is a cross-sectional view showing another example of the electrostatic chuck according to the first embodiment. The electrostatic chuck 1 shown in Figure 6 differs from the electrostatic chuck 1 shown in Figure 1 in that it is possible to supply power to the conductive layer 12 via a brazing material or other connecting part 16 by a power supply terminal 40 inserted into the interior of the adsorption substrate 10 through an opening 15 provided in the adsorption substrate 10. Note that the modes of power supply to the conductive layer 12 shown in Figures 1 and 6 are merely illustrative and are not limited to those shown.

[0035] <Second Embodiment> Figure 7 is a cross-sectional view showing an example of an electrostatic chuck having an adsorption substrate according to the second embodiment. Figure 8 is an enlarged view of region C shown in Figure 7.

[0036] The adsorption substrate 10 according to this embodiment differs from the adsorption substrate 10 according to the first embodiment in that the protruding portion 13 has a flat portion 17.

[0037] The flat portion 17 is connected to the second end face 132 of the protruding portion 13 and extends along the first surface 10a of the suction substrate 10. As shown in Figure 8, the protruding portion 13 having the flat portion 17 has a stepped shape in cross-sectional view. The area of ​​such a protruding portion 13, when viewed from the first surface 10a side in plan view, differs between the portion located between the flat portion 17 and the first end face 131 and the second end face 132.

[0038] The projection 13 has a third end face 171 and a fourth end face 172. The third end face 171 is in contact with the second end face 132. The fourth end face 172 is located away from the third end face 171. The portion of the projection 13 located between the third end face 171 and the fourth end face 172 is the flat portion 17.

[0039] Because the protruding portion 13 has a flat portion 17, even if the suction substrate 10 is subjected to an external force, for example, the protruding portion 13 is less likely to detach further from the base body 11, and the conductive layer 12 connected to the protruding portion 13 is less likely to peel off from the base body 11. As a result, delamination is less likely to occur with the suction substrate 10 according to this embodiment.

[0040] The diameter D5 of the first end face 131 can be, for example, 0.3 mm to 2.5 mm. The diameter D6 of the fourth end face 172 can be, for example, 0.5 mm to 3.0 mm. The diameter of the second end face 132 may be the same as or different from the diameter D5 of the first end face 131. Also, the diameter of the third end face 171 may be the same as or different from the diameter D6 of the fourth end face 172.

[0041] Furthermore, the area of ​​the flat portion 17 viewed from the first surface 10a side may be larger than the area of ​​the second end surface 132. This further reduces delamination.

[0042] Furthermore, the area of ​​the flat portion 17 may be smaller than that of the conductive layer 12 when viewed from the first surface 10a side. This makes it less likely for the protruding portion 13 to detach from the substrate 11 together with the flat portion 17. In particular, if the flat portion 17 is positioned such that the area of ​​the protruding portion 13 when viewed from the first surface 10a side, from the first end face 131 to the second end face 132, is 5% to 85% of the area of ​​the flat portion 17 when viewed from the first surface 10a side, the occurrence of delamination can be further reduced. Moreover, if the flat portion 17 is positioned such that the area of ​​the protruding portion 13 when viewed from the first surface 10a side, from the first end face 131 to the second end face 132, is 5% to 30% of the area of ​​the flat portion 17 when viewed from the first surface 10a side, delamination becomes even less likely.

[0043] Furthermore, the flat portion 17 has a thickness t3. This thickness t3 may be smaller than the first distance d1 between the first end face 131 and the second end face 132 of the protruding portion 13. Also, the thickness t3 of the flat portion 17 may be larger than the thickness t1 of the conductive layer 12. Here, the thickness t3 may be, for example, 1 μm or more. Also, the thickness t3 may be in the range of 2 μm to 20 μm. Also, the thickness t3 may be 0.5 μm to 3.0 μm.

[0044] Furthermore, the thickness t3 of the flat portion 17 may be greater than the thickness t1 of the conductive layer 12. Here, the thickness t3 can be, for example, in the range of 2 to 100 times the thickness t1.

[0045] The material of the flat portion 17 may be the same as that of the other parts of the protruding portion 13. Alternatively, the material of the flat portion 17 may be the same as that of the conductive layer 12.

[0046] The flat portion 17 may be located on each of the protrusions 13 that protrude from the conductive layer 12, or it may be located on only a part of them. Furthermore, the flat portion 17 may be positioned to straddle two or more protrusions 13.

[0047] The shape of the projection 13 having the flat portion 17 is not limited to that shown in Figure 8. For example, the diameter of the first end face 131 may be larger than the diameter of the fourth end face 172. Also, the projection 13 may have a columnar shape extending in a first direction (for example, the Y-axis direction) along the XY plane, and the flat portion 17 may have a columnar shape extending in a second direction (for example, the X-axis direction) intersecting the first direction, resulting in a projection 13 that is approximately X-shaped in plan view.

[0048] As described above, the presence of a flat portion 17 in the protrusion 13 changes the cross-sectional shape of the protrusion 13 in the thickness direction (Z-axis direction). This increases the surface area of ​​the protrusion 13. Consequently, the contact area between the protrusion 13 and the substrate 11 increases, making it more difficult for the conductive layer 12 connected to the protrusion 13 to peel off from the substrate 11. As a result, the adsorption substrate 10 shown in Figure 8 can further reduce the occurrence of delamination.

[0049] <Fabrication of adsorption substrates> The adsorption substrate 10 can be manufactured, for example, as follows.

[0050] (1) A molded body is obtained in which a conductive layer material and a protruding part material are positioned inside the base material.

[0051] (2) The molded body obtained in (1) above is fired. This yields an adsorption substrate 10 having a substrate 11, a conductive layer 12, and a protrusion 13, according to the shape and composition of the substrate raw material, conductive layer material, and protrusion material.

[0052] As described above, the adsorption substrate 10 according to the embodiment comprises an insulating base 11, a conductive layer 12, and a protrusion 13. The base 11 has a first surface 10a that holds the object to be processed and a second surface 10b located on the opposite side of the first surface. The conductive layer 12 is located inside the base 11 and extends along the first surface 10a. The protrusion 13 is located inside the base 11 and protrudes from the conductive layer 12 toward the second surface 10b. The protrusion 13 has a first end surface 131 that is in contact with the conductive layer 12 and a second end surface 132 located toward the second surface 10b. The first distance d1 between the first end surface 131 and the second end surface 132 is greater than half the thickness t1 of the conductive layer 12. This makes delamination less likely to occur.

[0053] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of this disclosure are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0054] 1. Electrostatic Chuck 10 Adsorption substrate 10a 1st page 10b 2nd side 11 Base 12. Conductive layer 13 Protrusion 17 Flat area 20 Heat exchanger 30 Bonding material 131 1st end face 132 Second end face d1 First distance d2 2nd distance d3 Third distance d4 4th distance t1 Thickness of the conductive layer t2 Thickness of the conductive layer t3 Thickness of the flat section

Claims

1. An insulating substrate having a first surface for holding the object to be processed and a second surface located opposite the first surface, A conductive layer located inside the substrate and extending along the first surface, Located inside the substrate, at least one protrusion projecting from the conductive layer toward the second surface side Equipped with, The protruding portion has a first end face that contacts the conductive layer and a second end face located on the second surface side. The second end face, at least a portion of which faces the base inside the base, is in direct or indirect contact with the base. An adsorption substrate in which the first distance between the first end face and the second end face is greater than half the thickness of the conductive layer.

2. The adsorption substrate according to claim 1, wherein the first distance is greater than the second distance between the first surface and the conductive layer.

3. The adsorption substrate according to claim 1, wherein the protruding portion has a cross-sectional shape that changes in the thickness direction.

4. The adsorption substrate according to claim 3, wherein the protruding portion is tapered.

5. The protruding portion is connected to the second end face and has a flat portion extending along the first face. The flat portion is located inside the base and has a third end face in contact with the second end face, and a fourth end face located opposite the third end face, the fourth end face facing the base and in direct or indirect contact with it. The adsorption substrate according to claim 1, wherein the area of ​​the flat portion viewed from the first surface is larger than the area of ​​the second end surface.

6. The protruding portion is connected to the second end face and has a flat portion extending along the first face. The flat portion is located inside the base and has a third end face in contact with the second end face, and a fourth end face located opposite the third end face, the fourth end face facing the base and in direct or indirect contact with it. The adsorption substrate according to claim 1, wherein the area of ​​the flat portion, when viewed from the first surface side, is smaller than that of the conductive layer.

7. The adsorption substrate according to claim 6, wherein the area of ​​the protruding portion viewed from the first surface is 5% to 30% of the area of ​​the flat portion viewed from the first surface.

8. The adsorption substrate has a plurality of protrusions that each protrude from the conductive layer, The adsorption substrate according to any one of claims 5 to 7, wherein the flat portion is connected to the second end face of each of the plurality of protrusions.

9. The adsorption substrate according to any one of claims 5 to 7, wherein the thickness of the flat portion is greater than the thickness of the conductive layer.

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