Sample holder

Abstract

To provide a sample holder that can process a wafer using high-power plasma.SOLUTION: A sample holder 1 disclosed herein includes a plate-shaped substrate 10 having a first surface 10a which is a sample holding surface and a second surface 10b opposite to the first surface 10a and having a gas hole 11 penetrating in a thickness direction, a support 20 formed of a through hole 21 that is joined to the second surface 10b of the substrate 10 and communicates with the gas hole 11, and a porous member 30 disposed inside the through hole 21, and including at least one dense layer 31, and at least one dense layer 31 is more dense than the other portion 32 of the porous member 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sample holder for holding a sample such as a semiconductor wafer, which is used in the manufacturing process of a semiconductor integrated circuit or a liquid crystal display device. [Background technology]

[0002] A known sample holder used in semiconductor integrated circuit manufacturing equipment includes a ceramic substrate having a sample support surface and a base substrate bonded to the ceramic substrate (see, for example, Patent Document 1). Such a sample holder is provided with a porous body for suppressing plasma discharge within through-holes formed in the ceramic substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-218352 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, with the miniaturization of semiconductor integrated circuits, samples have been processed using high-power plasma. With conventional sample holders, when the plasma output was increased, the plasma irradiated onto the sample could discharge to the base substrate via the gas filling the gap between the sample and the sample support surface. [Means for solving the problem]

[0005] The sample holder of the present disclosure includes a plate-shaped substrate having a first surface as a sample holding surface and a second surface opposite to the first surface, and having gas holes formed therethrough in the thickness direction; a support body bonded to the second surface of the base body and having a through hole communicating with the gas hole; The porous member is provided inside the through hole, and includes at least one dense layer, the at least one dense layer being denser than other portions of the porous member. [Effects of the Invention]

[0006] The sample holder of the present disclosure can limit the discharge path of plasma irradiated onto the sample and discharged to the support, making it difficult for plasma to discharge to the support, thereby enabling sample processing using high-power plasma. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a sample holder according to a first embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a main part of the sample holder of FIG. [Figure 3] FIG. 2 is a perspective view showing an example of a porous member in the sample holder of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along the cutting line AA in FIG. 3. [Figure 5] 1. FIG. 4 is a cross-sectional view showing another example of the porous member in the sample holder of FIG. [Figure 6] FIG. 10 is a cross-sectional view showing a sample holder according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the sample holder of the present disclosure will be described with reference to the accompanying drawings. The sample holder may be used with either direction designated as up or down, but for convenience, this specification defines a Cartesian coordinate system (X, Y, Z), and terms such as top and bottom are used, with the positive side of the Z axis being designated as the top in the height direction.

[0009] Fig. 1 is a cross-sectional view showing a sample holder according to the first embodiment, Fig. 2 is an enlarged cross-sectional view of a main part of the sample holder of Fig. 1, Fig. 3 is a perspective view showing an example of a porous member in the sample holder of Fig. 1, Fig. 4 is a cross-sectional view taken along the cutting line AA of Fig. 3, and Fig. 5 is a cross-sectional view showing another example of a porous member in the sample holder of Fig. 1. The cross-sectional view shown in Fig. 5 corresponds to the cross-sectional view shown in Fig. 4.

[0010] The sample holder 1 of this embodiment comprises a substrate 10 , a support 20 , and a porous member 30 .

[0011] The base 10 is a member for holding a sample (not shown) such as a semiconductor wafer. The base 10 has a flat plate shape along the XY plane. The base 10 has a first surface 10a, which is a sample holding surface, and a second surface 10b opposite to the first surface 10a. The base 10 is provided with a gas hole 11 that penetrates in the thickness direction (Z direction) from the first surface 10a to the second surface 10b. A plurality of gas holes 11 may be provided, for example, as shown in FIG. 1.

[0012] The base 10 is made of, for example, a ceramic material. Examples of ceramic materials used for the base 10 include alumina, aluminum nitride, silicon nitride, and yttria. The outer shape of the base 10 may be, for example, a disk, a rectangular plate, a polygonal plate, or other shape. The outer dimensions of the base 10 are, for example, a diameter (or side length) of 200 mm to 500 mm and a thickness of 2 mm to 15 mm.

[0013] Adsorption electrodes E1 and E2 are embedded in the substrate 10. By applying a voltage to the adsorption electrodes E1 and E2, an electrostatic force is generated between the adsorption electrodes E1 and E2 and the sample placed on the first surface 10a, thereby making it possible to hold the sample on the first surface 10a.

[0014] A heating resistor (not shown) is embedded in the substrate 10. By passing a current through the heating resistor, the heating resistor generates heat, thereby heating the sample held on the first surface 10a. The heating resistor may be disposed on the second surface 10b of the substrate 10.

[0015] The sample holder 1 is used, for example, by generating plasma above the first surface 10a. The plasma can be generated, for example, by applying a high-frequency voltage between a plurality of externally provided electrodes and ionizing the gas located between the electrodes.

[0016] The support 20 is a member for supporting the base 10. The support 20 has a flat plate shape along the XY plane. The support 20 has a third surface 20a facing the second surface 10b of the base 10, and a fourth surface 20b opposite the third surface 20a. The third surface 20a is bonded to the second surface 10b via a bonding material 40.

[0017] The support 20 is provided with a through-hole 21 that penetrates in the thickness direction (Z direction) from the third surface 20a to the fourth surface 20b. The through-hole 21 communicates with the gas hole 11 of the base 10, and the axial direction of the through-hole 21 is aligned with the axial direction of the gas hole 11. The gas hole 11 and the through-hole 21 form a gas supply hole H that allows a plasma generation gas, such as helium or argon, to flow from the fourth surface 20b side of the support 20 to the first surface 10a side of the base 10, which is the sample support surface. The sample holder 1 may have multiple gas supply holes H, as shown in FIG. 1, for example.

[0018] The support 20 is made of, for example, a metal material. Examples of metal materials used for the support 20 include aluminum and magnesium. The outer shape of the support 20 may be, for example, a disk, a rectangular plate, a polygonal plate, or other shape. The outer dimensions of the support 20 are, for example, a diameter (or side length) of 200 mm to 500 mm and a thickness of 10 mm to 100 mm. The support 20 may have the same outer shape as the base 10 or a different outer shape. Furthermore, the support 20 may have the same outer dimensions as the base 10 or different outer dimensions. As a bonding material used to bond the base 10 and the support 20, for example, an adhesive such as a silicone resin or an epoxy resin can be used.

[0019] 2, the inner diameter of through-hole 21 may be equal to or greater than the inner diameter of gas hole 11. This prevents third surface 20a of support 20 from being exposed within the opening of gas hole 11 when viewed from above first surface 10a in a direction perpendicular to first surface 10a, making it difficult for plasma irradiated onto the sample to discharge to support 20.

[0020] The porous member 30 is a member for suppressing discharge of plasma to the support 20. The porous member 30 has a cylindrical shape. The porous member 30 is positioned within the through-hole 21 of the support 20, and the axial direction of the porous member 30 is aligned with the axial direction of the through-hole 21. The porous member 30 has a fifth surface 30a positioned on the third surface 20a side of the support 20, a sixth surface 30b opposite the fifth surface 30a, and an outer peripheral surface 30c. The outer peripheral surface 30c may be in contact with the inner peripheral surface 21a of the through-hole 21. This fills the gap between the outer peripheral surface 30c and the inner peripheral surface 21a, making it difficult for plasma irradiated to the sample to discharge to the support 20. Note that if a cylindrical member made of an insulating material is provided within the through-hole 21, the outer peripheral surface 30c may be in contact with the inner peripheral surface of the cylindrical member.

[0021] The porous member 30 is made of, for example, an insulating material. Examples of insulating materials used for the porous member 30 include ceramic porous materials such as alumina, aluminum nitride, and silicon nitride. The porous member 30 has a porosity that allows the plasma generation gas to flow from the sixth surface 30b side toward the fifth surface 30a side.

[0022] In the sample holder 1 of this embodiment, the porous member 30 includes at least one dense layer 31. The dense layer 31 is denser than the other portion 32 of the porous member 30 other than the dense layer 31. In the porous member 30, for example, the porosity of the dense layer 31 is 0.1% to 10%, and the porosity of the other portion 32 is 20% to 60%.

[0023] The porosity of the dense layer 31 and the other portion 32 can be measured by analyzing an image of a cross section of the porous member 30 using, for example, a scanning electron microscope. Commercially available image analysis software may be used to analyze the image of the cross section of the porous member 30.

[0024] The dense layer 31 is made of a first ceramic material. Examples of the first ceramic material include alumina, aluminum nitride, and silicon nitride. The other portion 32 is made of a second ceramic material. Examples of the second ceramic material used for the other portion 32 include alumina, aluminum nitride, and silicon nitride. The first and second ceramic materials may have the same main component. This allows the thermal expansion coefficients of the dense layer 31 and the other portion 32 to be closer to each other, thereby reducing the thermal stress generated in the porous member 30 during plasma irradiation. This in turn prevents the dense layer 31 from peeling off from the other portion 32 due to the thermal stress generated in the porous member 30 during plasma irradiation, thereby improving the durability of the porous member 30. As a result, the durability and reliability of the sample holder 1 can be improved.

[0025] In the sample holder 1, part of the plasma irradiated to the sample propagates through the plasma generating gas filling the space between the sample and the first surface 10a, and enters the gas supply holes H. The plasma that entered the gas supply holes H is incident on the porous member 30. The movement of the plasma that entered the porous member 30 within the porous member 30 is restricted by the dense layer 31, which has a relatively high porosity and makes it difficult for the plasma to pass through, making it difficult for the plasma to concentrate in a specific area of ​​the porous member 30, and restricting the discharge path to the support 20. As a result, in the sample holder 1, it is difficult for the plasma to discharge to the support 20, and ultimately it becomes possible to process the sample using high-power plasma.

[0026] The at least one dense layer 31 may be a plurality of dense layers 31a-31c. The dense layers 31a-31c may be arranged at intervals from one another in a predetermined stacking direction S, as shown in Figures 3 and 4, for example. This allows the porous member 30 to effectively restrict the movement of plasma within it, making it more difficult for plasma to concentrate in a specific region of the porous member 30 and further restricting the discharge path to the support 20. As a result, it becomes more difficult for plasma to be discharged to the support 20, and ultimately it becomes possible to process samples using higher-power plasma.

[0027] The stacking direction S of the dense layers 31a-31c may be inclined with respect to the thickness direction of the substrate 10, i.e., the axial direction of the gas supply holes H. This makes it easier for plasma that enters the gas supply holes H and enters the porous member 30 to collide with the dense layer 31. Therefore, the porous member 30 can more effectively restrict the movement of plasma within itself, making it less likely for plasma to concentrate in a specific region of the porous member 30 and further restricting the discharge path to the support 20. As a result, it becomes more difficult for plasma to be discharged by the support 20, and ultimately, it becomes possible to process samples using even higher-power plasma. The angle between the stacking direction S and the axial direction of the gas holes 11 may be, for example, 20° to 70°, 30° to 60°, or 40° to less than 50°.

[0028] The other portion 32 of the porous member 30 may be divided into a plurality of regions 32a to 32d by a plurality of dense layers 31a to 31c, as shown in Figures 3 and 4, for example. The plurality of regions 32a to 32d may have different porosities. For example, the porosity of the regions 32a and 32d located at both ends in the stacking direction S may be higher than the porosity of the regions 32b and 32c located in the center. The flow rate of the plasma generation gas flowing through the through hole 21 in the region near the inner circumferential surface 21a tends to be lower than the flow rate in the central region located inside the region near the inner circumferential surface 21a as viewed in the axial direction of the through hole 21, due to friction loss at the inner circumferential surface 21a, for example. In the porous member 30, the porosity of the regions 32a and 32d is greater than the porosity of the regions 32b and 32c, so that the flow rate of the plasma generation gas in the central region can be reduced and the flow rate of the plasma generation gas in the nearby regions can be increased, thereby making the flow rate in the central region and the flow rate in the nearby regions closer to each other. As a result, it becomes possible to control with high precision the flow rate of the plasma generation gas supplied above the first surface 10a through the gas supply holes H, and the processing performance of the sample holder 1 can be improved.

[0029] The dense layers 31a to 31c may have different thicknesses in the stacking direction S. For example, the dense layers 31a to 31c may have a centrally located dense layer 31b thicker than the dense layers 31a and 31c located at both ends in the stacking direction S. This also allows the porous member 30 to make the flow rate of the plasma generation gas in the region near the inner circumferential surface 21a closer to the flow rate of the plasma generation gas in the central region inside the region near the inner circumferential surface 21a as viewed in the axial direction of the through-hole 21. This in turn makes it possible to control with high precision the flow rate of the plasma generation gas supplied above the first surface 10a through the gas supply holes H, thereby improving the processing performance of the sample holder 1.

[0030] In the porous member 30, the gap between adjacent dense layers 31 may be narrower in the center in the stacking direction S and wider at both ends. This also enables the porous member 30 to make the flow rate of the plasma generation gas in the region near the inner circumferential surface 21a closer to the flow rate of the plasma generation gas in the central region inside the region near the inner circumferential surface 21a as viewed in the axial direction of the through-hole 21. Consequently, it becomes possible to control with high precision the flow rate of the plasma generation gas supplied above the first surface 10a through the gas supply holes H, thereby improving the processing performance of the sample holder 1.

[0031] Although Figures 3 and 4 show an example in which the porous member 30 includes three dense layers 31a to 31c, the porous member 30 may include one or two dense layers 31, or may include four or more dense layers 31.

[0032] The dense layer 31 may have a corrugated shape when viewed in cross section along the stacking direction S, as shown in FIG. 5 , for example. This allows the porous member 30 to deflect plasma incident on the porous member 30 in various directions. Therefore, the plasma incident on the porous member 30 is less likely to concentrate in a specific region of the porous member 30, and the discharge path to the support 20 is further restricted and lengthened. As a result, plasma is less likely to be discharged to the support 20, which in turn enables sample processing using higher-power plasma. Furthermore, the corrugated shape of the dense layer 31 increases the area of ​​the interface between the dense layer 31 and the other portion 32. This prevents the dense layer 31 from peeling off from the other portion 32 due to thermal stress generated in the porous member 30 during plasma irradiation.

[0033] 1 and 2, the sample holder 1 may include a cylindrical member (hereinafter also referred to as a sleeve) 50 located inside the through-hole 21 of the support 20. The sleeve 50 is a member for preventing the inner circumferential surface 21a of the through-hole 21 from being exposed to plasma. The sleeve 50 is, for example, a cylindrical member extending along the axial direction of the through-hole 21.

[0034] The sleeve 50 is made of, for example, an insulating material, such as a ceramic material such as alumina or aluminum nitride.

[0035] The sleeve 50 is held by the support body 20, for example, by bonding its outer peripheral surface 50a to the inner peripheral surface 21a of the through hole 21 via a bonding material. The bonding material used to bond the sleeve 50 to the support body 20 may be, for example, an adhesive such as a silicone resin or an epoxy resin. The bonding material 40 used to bond the base 10 to the support body 20 may enter the gap between the outer peripheral surface 50a and the inner peripheral surface 21a to bond the sleeve 50 to the support body 20.

[0036] By providing the sample holder 1 with the sleeve 50, even if the plasma that has entered the gas supply hole H passes through the porous member 30, the plasma that has passed through the porous member 30 can be prevented from discharging to the support 20.

[0037] 2, the inner diameter of the sleeve 50 at its upper end may be larger than that at its lower end. This allows the porous member 30 to be positioned so that its outer peripheral surface 30c is surrounded by the sleeve 50. As a result, it is possible to effectively prevent the plasma that has entered the porous member 30 from discharging to the support body 20. Furthermore, even if the plasma that has entered the gas supply hole H passes through the porous member 30, the relatively thick lower end portion of the sleeve 50 can prevent the plasma that has passed through the porous member 30 from discharging to the support body 20.

[0038] 1 and 2, the fifth surface 30a of the porous member 30 may be located below the third surface 20a of the support body 20. This increases the creeping distance between the fifth surface 30a of the porous member 30 and the inner circumferential surface 21a of the through hole 21, thereby suppressing the occurrence of creeping discharge between the fifth surface 30a and the inner circumferential surface 21a.

[0039] Next, another embodiment of the sample holder of the present disclosure will be described.

[0040] 6 is a cross-sectional view showing a sample holder according to the second embodiment. The sample holder 1A of the second embodiment differs from the sample holder 1 of the first embodiment in the configurations of the gas holes 11 in the substrate 10 and the through-holes 21 in the support 20, and in the positions of the porous member 30 and the sleeve 50. The rest of the configuration is the same, so detailed description of the similar configuration will be omitted.

[0041] 6, in the sample holder 1A, the upper end surface 50b of the sleeve 50 protrudes above the third surface 20a of the support 20, and a recess 12 that opens downward is formed in the second surface 10b of the base 10. By forming the recess 12 in the second surface 10b of the base 10, it becomes easy to position the base 10 and the support 20, and it also becomes easy to communicate between the gas hole 11 and the through-hole 21.

[0042] Furthermore, in the sample holder 1A, the porous member 30 is located from the inside of the through-hole 21 to the inside of the recess 12, and the fifth surface 30a of the porous member 30 is located higher than the third surface 20a of the support 20. As a result, the plasma that has entered the gas supply hole H is incident on the porous member 30 before reaching the support 20, and the porous member 30 has a significant effect of suppressing discharge of plasma to the support 20. In this way, the sample holder 1A can effectively suppress discharge of plasma to the support 20, and ultimately makes it possible to process samples using high-power plasma.

[0043] Furthermore, in the sample holder 1A, the fifth surface 30a is located higher than the third surface 20a, which makes it possible to increase the creeping distance between the fifth surface 30a and the inner circumferential surface 21a of the through-hole 21 compared to when the fifth surface 30a and the third surface 20a are at the same height. This makes it possible to suppress the occurrence of creeping discharge between the fifth surface 30a and the inner circumferential surface 21a.

[0044] The fifth surface 30a may be at the same height as the upper end surface 50b of the sleeve 50, or may be at a height between the upper end surface 50b of the sleeve 50 and the third surface 20a of the support body 20. When the fifth surface 30a is at a height between the upper end surface 50b of the sleeve 50 and the third surface 20a, the creeping distance between the fifth surface 30a and the inner circumferential surface 21a of the through hole 21 becomes longer, thereby effectively suppressing the occurrence of creeping discharge between the fifth surface 30a and the inner circumferential surface 21a.

[0045] In the sample holder 1A, the bonding material 40 enters between the outer peripheral surface 50a of the sleeve 50 and the inner peripheral surface 12a of the recess 12, bonding the sleeve 50 to the base 10. As shown in Fig. 6, for example, the bonding material 40 is not located between the upper end surface 50b of the sleeve 50 and the bottom surface 12c of the recess 12, so that the bonding material 40 can be prevented from coming into contact with plasma and being deteriorated.

[0046] The above describes in detail the embodiments of the present disclosure, but the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure. [Explanation of symbols]

[0047] 1,1A Sample holder 10 Base 10a 1st page 10b 2nd side 11 Gas vent 12 recess 12a Inner surface 20 Support 20a, Side 3 20b Side 4 21 Through hole 21a Inner surface 30 Porous material 30a 5th page 30b Page 6 30c outer circumferential surface 31,31a,31b,31c compact layer 32, 32a, 32b, 32c, 32d Other parts 40 Bonding material 50 Cylindrical member (sleeve) 50a outer peripheral surface 50b upper face

Claims

1. a plate-like substrate having a first surface serving as a sample support surface and a second surface opposite to the first surface, the substrate having gas holes formed therethrough in a thickness direction; a support having a third surface facing the second surface and a fourth surface opposite the third surface, the third surface facing the second surface and having a through hole communicating with the gas hole; a porous member having a fifth surface located on the third surface side of the support, a sixth surface opposite to the fifth surface, and an outer peripheral surface, and having a dense layer that is denser than other portions, the porous member has a plurality of the dense layers, the third surface is bonded to the second surface of the base via a bonding material; In a planar perspective view, the bonding material extends further toward the gas hole than an inner circumferential surface of the through hole, the bonding material is located between an inner circumferential surface of the through hole and the porous member, A sample holder, wherein a plurality of the dense layers are located on the outer peripheral surface of the porous member facing the inner peripheral surface of the through hole.

2. 2. The sample holder according to claim 1, wherein the thicknesses of the dense layers are different from each other.

3. 3. The sample holder according to claim 1, wherein the fifth surface of the porous member is located below the third surface of the support.

4. a plate-like substrate having a first surface serving as a sample support surface and a second surface opposite to the first surface, the substrate having gas holes formed therethrough in a thickness direction; a support having a third surface facing the second surface and a fourth surface opposite the third surface, the third surface facing the second surface and having a through hole communicating with the gas hole; a porous member having a fifth surface located on the third surface side of the support, a sixth surface opposite to the fifth surface, and an outer peripheral surface, and having a dense layer that is denser than other portions, the dense layer is a fractional dense layer extending in at least one of the fifth surface, the outer circumferential surface, and the sixth surface so as to fractionate the other portion into a plurality of regions, A sample holder having a plurality of the fractional dense layers, the thicknesses of the fractional dense layers being different from one another.

5. 5. The sample holder according to claim 4, wherein the fractional dense layer is connected from the fifth surface to the outer peripheral surface and further to the sixth surface, and extends so as to fractionate the other portions on each surface.

6. The sample holder of claim 4 or 5, wherein the multiple fractionated dense layers are arranged at both ends corresponding to the region near the outer surface and at a central portion corresponding to a central region inside the region near the outer surface, and the fractionated dense layer located in the central portion has a thickness greater than that of the fractionated dense layer located at both ends.

7. the third surface is bonded to the second surface of the base via a bonding material; 7. The sample holder according to claim 4, wherein, in a plan view, the bonding material extends further toward the gas hole than the inner circumferential surface of the through hole.

8. a recessed portion that opens downward is formed on the second surface of the base, and the porous member is positioned from inside the through hole to inside the recessed portion, 7. The sample holder according to claim 4, wherein the fifth surface of the porous member is located above the third surface of the support.

9. A sample holder according to any one of claims 4 to 8, further comprising a cylindrical member extending along the axial direction of the through hole between the inner peripheral surface of the through hole of the support and the porous member.

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