JP2017152469A - Sample holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sample holder 10 having high dielectric withstanding voltage in a plasma atmosphere.SOLUTION: A sample holder 10 of the invention has: a base substance 1; an external conductor layer 4 provided on a lower surface of the base substance 1; a support medium 2 made of metal and including an upper surface that covers a lower surface of the base substance 1 together with the external conductor layer 4; and a joint layer 3 which joins the lower surface of the base substance 1 to the support medium 2 and is formed by a resin material. The joint layer 3 has: a first portion 31 which is at least partially provided at a center side; and a second portion 32 positioned at the outer periphery side of the joint layer 3. The second portion 32 contains carbon more than the first portion 31.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sample holder used for holding each sample such as a semiconductor wafer in a manufacturing process of a semiconductor integrated circuit.

  As a sample holder used in a semiconductor manufacturing apparatus or the like, for example, a substrate mounting apparatus described in Patent Document 1 is known. This substrate mounting apparatus is provided with a plate-like ceramic base material having a substrate mounting surface on one surface, a bonding layer formed on the other surface of the ceramic base material, and the other surface of the ceramic base material. And a base that is bonded via a bonding layer.

JP 2006-13302 A

  However, in recent years, with the miniaturization of wiring of a semiconductor integrated circuit, wafer processing is performed in a plasma with higher output. Therefore, the outer surface of the bonding layer of the sample holder is easily charged due to the influence of plasma. On the lower surface of the ceramic substrate, an external conductor layer such as a heating resistor for heating the sample and an adsorption electrode for electrostatically adsorbing the sample is provided. There is a possibility that dielectric breakdown occurs between the outer conductor layers due to the electric charge charged on the outer surface of the bonding layer.

  The sample holder of the present invention includes a substrate, an outer conductor layer provided on the lower surface of the substrate, a support made of metal and covering the lower surface of the substrate with the outer conductor layer on the upper surface, the lower surface of the substrate and the support A bonding layer made of a resin material that bonds the body, and the bonding layer includes a first portion at least partially provided on the center side and a second portion positioned on the outer peripheral side of the bonding layer. And the second part contains more carbon than the first part.

  According to the sample holder of one aspect of the present invention, since the second portion located on the outer peripheral side of the bonding layer contains a large amount of carbon, the second portion has high conductivity and is difficult to be charged. Even when used in a high-power plasma atmosphere, a sample holder in which the possibility of dielectric breakdown between outer conductor layers such as a heating resistor provided on the lower surface of the substrate can be reduced.

It is sectional drawing which shows the sample holder of an example of this embodiment. It is sectional drawing which shows the other example of embodiment of a sample holder. It is sectional drawing which expands and shows the principal part (A part) of FIG. 1 or FIG. It is sectional drawing which shows the principal part of the modification of a sample holder. It is sectional drawing which shows the principal part of the modification of a sample holder. It is sectional drawing which shows the principal part of the modification of a sample holder. It is sectional drawing which shows the principal part of the modification of a sample holder.

  Hereinafter, an example sample holder 10 according to the present embodiment will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a sample holder 10 as an example of the present embodiment. As shown in FIG. 1, the sample holder 10 includes a base body 1, an external conductor layer 4 provided on the lower surface of the base body 1, and a support 2 that is made of metal and covers the lower surface of the base body 1 together with the outer conductor layer 4. And a bonding layer 3 made of a resin material for bonding the lower surface of the base 1 and the support 2 to each other. The “upper surface” and “lower surface” here are expressions used for convenience of explanation, and do not limit the method of using the sample holder 10. That is, the sample holder 10 may be used, for example, with the upper surface on the lower side (with the lower surface on the upper side), or with the upper surface on the horizontal side.

  The substrate 1 is a plate-like member having a sample holding surface on the upper surface. The substrate 1 holds a sample such as a silicon wafer on the upper sample holding surface. The sample holder 10 is a member having a circular shape when viewed from above. The substrate 1 is made of, for example, a ceramic material such as alumina, aluminum nitride, silicon nitride, or yttria, or a metal material such as aluminum or stainless steel. The dimensions of the substrate 1 can be set, for example, to a diameter of 200 mm to 500 mm and a thickness of 0.5 mm to 15 mm.

  An outer conductor layer 4 is provided on the lower surface of the substrate 1. The external conductor layer 4 is an adsorption electrode or a heating resistor when the substrate 1 is made of a ceramic material, and is a heating resistor when the substrate 1 is made of a metal material. FIG. 2 is a cross-sectional view showing a sample holder 10 of another example of the present embodiment. In this example, the sample holder 10 is provided with an inner conductor layer 5 inside the base 1 in addition to the outer conductor layer 4. In this case, the inner conductor layer 5 is, for example, an adsorption electrode, the outer conductor layer 4 is, for example, a heating resistor, and FIG. 2 shows such an example.

  Various methods can be used as a method of holding the sample using the substrate 1, and one method is a method of holding the sample by electrostatic force. The adsorption electrode is for that purpose. The adsorption electrode is composed of two electrodes. One of the two electrodes is connected to the positive electrode of the power source, and the other is connected to the negative electrode. The two electrodes are each formed so that the shape in plan view is substantially semicircular, and the semicircular chords oppose each other. These two electrodes are combined to form a circular outer shape of the adsorption electrode. The center of the circular outer shape of the entire suction electrode is set to be the same as the center of the outer shape of the circular substrate 1. The adsorption electrode may be provided in parallel to the lower surface of the substrate 1 made of a ceramic material, or the upper surface that is the sample holding surface inside the substrate 1.

  The heating resistor is for heating the sample held on the sample holding surface on the upper surface of the substrate 1. By applying a voltage to the heating resistor, the heating resistor 2 can generate heat. The heat generated by the heating resistor is transmitted through the inside of the substrate 1 and reaches the upper surface of the substrate 1 which is a sample holding surface. Thereby, the sample held on the sample holding surface can be heated. The heating resistor is a linear pattern having a plurality of folded portions, and is provided on almost the entire lower surface of the base 1. Thereby, it can suppress that dispersion | variation arises in heat distribution in the upper surface of the sample holder 10. FIG. Note that the heating resistor may be provided in the substrate 1 in parallel to the sample holding surface. That is, both the outer conductor layer 4 and the inner conductor layer 5 may be heating resistors.

If the substrate 1 is made of a ceramic material, the external conductor layer 4 (heating resistor or adsorption electrode) may contain a glass component in addition to the conductor component. As a conductor component, metal materials, such as silver palladium, platinum, aluminum, or gold | metal | money, are contained, for example. In order to suppress the foaming of the glass component, it is preferable to select a metal that can be sintered in the atmosphere as the metal material. The glass component includes oxides of materials such as silicon, aluminum, bismuth, calcium, boron, and zinc. When the heating resistor is provided inside the substrate 1, the conductor component may be tungsten, molybdenum, tungsten carbide, or the like. A pattern of the external conductor layer 4 can be formed on a green sheet mainly composed of a ceramic material to be the base 1 with a paste containing a component to be the external conductor layer 4, and these can be formed by simultaneous firing. Alternatively, the substrate 1 made of a ceramic material can be manufactured, and then the paste can be baked on the lower surface of the substrate 1.

  When the substrate 1 is made of metal, the outer conductor layer 4 is a heating resistor, and is made of, for example, an alloy containing nickel, base, iron, chromium, niobium, molybdenum or the like. An outer conductor layer is formed by attaching a polyimide film on one surface of the substrate 1, placing the above-described alloy in a linear pattern shape as described above, and further covering the polyimide film thereon. A substrate 1 having 4 (heating resistor) can be produced.

The support 2 is provided to support the base 1. The support 2 is made of metal, and covers the lower surface of the substrate 1 with the upper surface. The lower surface of the substrate 1 and the upper surface of the support 2 are bonded by the bonding layer 3. The support 2 can also function as a cooling plate for cooling the substrate 1. Therefore, the support 2 is made of a metal having a relatively high thermal conductivity. The metal constituting the support 2 is not particularly limited. The term “metal” as used herein includes composite materials made of metal, such as composite materials of ceramics and metal and fiber reinforced metals. In general, when the sample holder 10 is used in an environment exposed to a halogen-based corrosive gas or the like, aluminum (Al), copper (Cu), stainless steel, It is preferable to use nickel (Ni) or an alloy of these metals. Further, the structure of the support 2 is not particularly limited, but may be provided with a cooling flow path for circulating a heat medium such as gas or liquid. In this case, a liquid such as water or silicone oil, or a gas such as helium (He) or nitrogen (N ₂ ) can be used as the heat medium.

  The bonding layer 3 is provided for bonding the base 1 and the support 2. The bonding layer 3 bonds the lower surface of the substrate 1 and the upper surface of the support 2.

  Here, the bonding layer 3 includes a first portion 31 at least a part of which is provided on the center side, and a second portion 32 located on the outer peripheral side of the bonding layer 3, and the second portion 32 is the first portion 31. Contains more carbon than Since the second portion 32 containing a large amount of carbon has high conductivity and is difficult to be charged on the outer surface of the bonding layer 3, even if it is used in a high-power plasma atmosphere, the heating resistance provided on the lower surface of the substrate 1. The possibility of dielectric breakdown between the outer conductor layers 4 such as the body is reduced.

  In addition, since the second portion 32 located on the outer peripheral side of the bonding layer 3 contains more carbon than the first portion 31 located on the inner peripheral side, the outer peripheral portion of the bonding layer 3 is uniform on the surface of the substrate 1. Thermal properties are improved. Since the plasma circulates not only to the upper surface of the sample holder 10 (base 1) but also to the side, the surface temperature of the outer peripheral surface of the bonding layer 3 tends to rise due to the circulated plasma. On the other hand, the second portion 32, which is the outer peripheral portion including the outer peripheral surface of the bonding layer 3, contains a large amount of carbon and thus has a high thermal conductivity. Therefore, heat easily escapes from the outer peripheral portion of the bonding layer 3 to the support 2. Therefore, as compared with the case where the thermal conductivity of the bonding layer 3 is the same between the central side and the outer peripheral side, the temperature rise at the outer peripheral portion of the bonding layer 3 can be suppressed, so that the thermal uniformity of the entire surface of the substrate 1 is improved. To do.

  The dimensions of the bonding layer 3 can be set, for example, to a diameter of about 200 mm to 500 mm, as in the case of the substrate 1, and the thickness can be set to, for example, about 0.1 mm to 2.0 mm. The 2nd part 32 can be set to the annular | circular shaped part of the width | variety of about 0.5 mm-40 mm from the outer periphery among the joining layers 3, for example. In other words, the second portion 32 can be set in an annular shape having an outer diameter of 200 mm to 500 mm and an inner diameter of 120 mm to 499 mm. Although the width of the second portion 32 may differ in the thickness direction of the bonding layer 3, the width measured at the center in the thickness direction is the width of the second portion 32. The first portion 31 is located inside the second portion 32 of the bonding layer 3.

  The bonding layer 3 is made of a resin material, and for example, a silicone resin or an epoxy resin can be used. The first portion 31 and the second portion 32 may be the same type of resin material and different in carbon content. Different resin materials may have different carbon contents. The bonding layer 3 may contain a filler component such as ceramic particles in order to improve the thermal conductivity.

  Here, “the second portion 32 contains more carbon than the first portion 31” can be confirmed by using EPMA (Electron Probe Micro Analyzer). By performing color mapping for carbon (C), it is possible to confirm the second portion 32 having a large amount of carbon and the first portion 31 having a small amount of carbon. Further, the amount of carbon can be quantitatively analyzed using a WDS (Wavelength Dispersive X-ray Spectrometer) attached to EPMA. For example, the carbon amount measured at an arbitrary location in the region of 0.3 mm from the outer peripheral surface of the bonding layer 3 is the carbon amount of the second portion 32, and the arbitrary location within the region whose distance from the outer peripheral surface is 50 mm to 60 mm. The carbon amount measured in step 1 may be the carbon amount of the first portion 31. The measurement location may be the center of the bonding layer 3 in the thickness direction. The carbon content of the first portion 31 may be 0.5% by mass or less, and the carbon content of the second portion 32 may be 2 to 10% by mass. In particular, if the amount of carbon in the second portion 32 is 2% by mass or more, the outer surface of the bonding layer 3 is difficult to be charged. More preferably, the carbon content of the second portion 32 is 5% by mass or more. Further, when the carbon content of the second portion 32 is 10% by mass or less, even when the outer conductor layer 4 is covered by the second portion 32, the outer conductor layer 4 and the outer conductor layer 4 and the support body are supported. There is no risk of short circuit due to a decrease in insulation between the two. Even if the substrate 1 is made of a metal material, the insulation between the substrate 1 and the support 2 is lowered, and there is no possibility of short circuit. In addition, the thermal conductivity is larger on the outer peripheral side than on the central side of the bonding layer 3, and the thermal uniformity of the surface of the substrate 1 is improved.

  Further, as in the example shown in FIG. 4, when the cross section perpendicular to the lower surface of the base 1 is viewed, the second portion 32 is between the first portion 31 and the base 1 and between the first portion 31 and the support 2. And the second portion 32 may be bent in an arc shape so that the second portion 32 is recessed. In other words, when the cross section perpendicular to the lower surface of the substrate 1 is viewed, the boundary between the first portion 31 and the second portion 32 may be an outwardly convex curved shape (an isolated shape). Thereby, even if the thermal conductivity is different between the first portion 31 and the second portion 32, the temperature gradient in the vicinity of the boundary between the first portion 31 and the second portion 32 can be moderated, which is a sample holding surface. The soaking property on the upper surface of the substrate 1 is improved. In addition, by forming the boundary between the first portion 31 and the second portion 32 in an arc shape, it is possible to reduce the possibility that a crack or the like is generated when thermal stress is generated at the boundary under a heat cycle. In particular, when used in an environment where there is a large amount of heat to the outside, the first portion 31 expands significantly compared to the second portion 32, so that the second portion 32 is recessed at the boundary. By making the arc shape, the stress generated by the thermal expansion of the first portion 31 can be easily absorbed by the second portion 32.

  Further, as in the example shown in FIG. 5, when the external conductor layer 4 is a heating resistor, the second portion 32 is more closely connected to the first portion 31 than between the first portion 31 and the support 2. It may enter deeply between the base 1. In other words, the boundary between the second portion 32 and the first portion 31 may be concave, and the inner end on the base 1 side may be located more inside than the inner end on the support 2 side. Thereby, since the area where the first portion 31 and the second portion 32 overlap in the thickness direction of the bonding layer 3 is increased on the lower surface side of the substrate 1 provided with the heating resistor, the substrate provided with the heating resistor. Since the temperature gradient immediately below the lower surface of 1 can be made more gradual, the thermal uniformity on the upper surface of the substrate 1 which is the sample holding surface is improved.

In the case of the example shown in FIGS. 4 and 5, the width of the region where the first portion 31 and the second portion 32 overlap when viewed in the direction perpendicular to the lower surface of the substrate 1 is about 0.1 to 10 mm. Can be set. When the second portion 32 is deeper between the first portion 31 and the base body 1 than between the first portion 31 and the support 2 as in the example shown in FIG. The position of the end portion (inner end) on the substrate 1 side only needs to enter the inside of about 0.05 mm to 5 mm from the position of the end portion (inner end) on the support 2 side.

  Further, as in the example shown in FIG. 6, the sample holder 10 of the present invention has the first portion 31 and the second portion 32 adjacent to each other, and the boundary between the first portion 31 and the second portion 32. An uneven shape may be used. Thereby, the adhesive force between the first portion 31 and the second portion 32 is improved by the anchor effect, and the adhesive strength between the base 1 and the support 2 is improved. The degree of unevenness can be set, for example, such that the difference between peaks and valleys is about 0.02 mm to 2 mm, and the interval between peaks and peaks is about 0.01 mm to 0.3 mm.

  1 to 7, the outer conductor layer 4 may have a portion covered by the first portion 31 and a portion covered by the second portion 32. As a result, a portion of the outer conductor layer 4 located on the outer peripheral side of the base body 1 is covered with the second portion 32. The second portion 32 containing more carbon than the first portion 31 has a higher thermal conductivity than the first portion 31. The portion located on the outer peripheral side of the outer conductor layer 4 is likely to rise in temperature due to the influence of plasma, but since it is easy to dissipate heat to the support 2 through the second portion 32 having a high thermal conductivity, the overall thermal uniformity is high. Get better.

  In addition, as in the example illustrated in FIG. 7, the bonding layer 3 includes the third portion 33 positioned between the first portion 31 and the second portion 32, and the density of the third portion 33 is the first portion 31. And the density of the second portion 32 may be smaller. Since the second portion 32 and the first portion 31 are connected by the third portion 33 having a lower density than these, the stress caused by the difference in thermal expansion between the second portion 32 and the first portion 31 is applied to the third portion. Therefore, the durability of the bonding layer 3 is improved.

  As the material of the third portion 33, for example, a material that is the same resin material as the first portion 31 and the second portion 32 and has more pores than the first portion 31 and the second portion 32 can be used. By including many pores (air), the density is smaller than that of the first portion 31 and the second portion 32. The density of each of the first part 31, the second part 32, and the third part 33 can be measured by Archimedes method (Method A of JIS K 7112) using a sample obtained by cutting out each part. The density of the third portion 33 can be set to be 5 to 30% smaller than that of the first portion 31 and the second portion 32. In addition, the magnitude relationship between the porosity of the third portion 33 and the porosity of the first portion 31 and the porosity of the second portion 32 obtained by observing the cross section of the bonding layer 3 is expressed by the density of the third portion 33. It may be regarded as a magnitude relationship between the density of the first portion 31 and the density of the second portion 32. The porosity by the cross-sectional observation of the bonding layer 3 may be the porosity in the cross-sectional image. For example, the porosity may be about 1% or less for the first portion 31 and about 5% to 30% for the second portion 32. It can also be measured using image processing software or the like. The porosity can also be determined by the Archimedes method.

The bonding layer 3 having the first portion 31 and the second portion 32 can be formed as follows, for example. First, the entire lower surface of the substrate 1 and the support 2 are bonded with a resin material to be the first portion 31 and cured. The first portion 31 on the center side is formed by removing the cured resin material from the outer periphery to a depth of 0.5 to 10.0 mm. Next, the second part 32 is formed by filling a resin material that becomes the second part 32 into a space surrounded by the outer peripheral surface of the first part 31, the base 1, and the support 2 and curing the resin material. The shape of the boundary between the first portion 31 and the second portion 32 can be adjusted by adjusting the shape of the outer peripheral surface of the first portion 31 when the outer peripheral portion is removed. Alternatively, for example, a resin material that becomes the first portion 31 is applied to the central portion of the lower surface of the base body 1, placed on the upper surface of the support 2, the resin is cured and bonded, and then the outer periphery of the first portion 31. The space surrounded by the surface, the substrate 1 and the support 2 is filled with a resin material to be the second portion 32 and cured to form the second portion 32. Further, a resin material to be the first portion 31 is applied to the central portion of the lower surface of the base 1, and the resin material to be the second portion 32 is applied to the outer side of the resin material before it is completely cured. It may be placed on the upper surface of the body 2 and the two resins may be cured and bonded. The shape of the outer peripheral surface of the first portion 31 can be adjusted by the viscosity of the resin used, a mold may be used, and the outer peripheral surface of the cured first portion 31 may be ground. The third portion 33 is located between the first portion 31 and the second portion 32 without containing bubbles (air) by stirring the liquid resin material, for example. By applying and curing in this manner, a large number of pores can be included. The porosity can be adjusted by stirring conditions and defoaming conditions.

1: Substrate 2: Support 3: Bonding layer 31: First part 32: Second part 33: Third part 4: External conductor layer 5: Internal conductor layer 10: Sample holder

Claims (6)

  A base, an outer conductor layer provided on the lower surface of the base, a support made of metal and covering the lower surface of the base with the outer conductor layer on the upper surface, and a resin material that joins the lower surface of the base and the support The bonding layer has a first portion at least a part of which is provided on the center side, and a second portion located on the outer peripheral side of the bonding layer, and the second portion is The sample holder characterized by containing more carbon than the said 1st part.   When the cross section perpendicular to the lower surface of the base is viewed, the second part enters between the first part and the base and between the first part and the support, and the second part is 2. The sample holder according to claim 1, wherein the second portion is bent in an arc shape so that the second portion is recessed.   The outer conductor layer is a heating resistor, and the second portion is deeper between the first portion and the base body than between the first portion and the support. The sample holder according to claim 2.   2. The sample holder according to claim 1, wherein the first portion and the second portion are adjacent to each other, and a boundary between the first portion and the second portion is an uneven shape.   The sample holder according to any one of claims 1 to 4, wherein the outer conductor layer has a portion covered with the first portion and a portion covered with the second portion. .   The bonding layer has a third portion positioned between the first portion and the second portion, and the density of the third portion is smaller than the density of the first portion and the density of the second portion. The sample holder according to claim 1.

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