Electrostatic chuck

Abstract

This invention provides an electrostatic chuck comprising: a conductive base plate having a first portion and a second portion disposed on the outer periphery of the first portion, and having a gas inlet path for introducing cooling gas; a first electrostatic chuck portion disposed on the first portion, configured to adsorb a wafer, having a ceramic dielectric substrate having at least one through hole communicating with the gas inlet path and a first adsorption electrode embedded in the ceramic dielectric substrate; and a second electrostatic chuck portion disposed on the second portion, configured to adsorb a focusing ring, having a ceramic layer having at least one through hole for introducing cooling gas, the ceramic layer having at least a first layer that contacts the focusing ring when it is adsorbed onto the second electrostatic chuck portion, the density of the first layer being less than the density of the ceramic dielectric substrate. Thus, an electrostatic chuck is provided that can improve the yield of equipment.

Description

Technical Field

[0001] The present invention generally relates to an electrostatic chuck. Background Technology

[0002] In plasma processing chambers used for etching, chemical vapor deposition (CVD), sputtering, ion implantation, polishing, etc., a workpiece placement device, including an electrostatic chuck, is used to hold and hold semiconductor wafers or glass substrates. An electrostatic chuck is a device that uses electrostatic force to hold substrates such as silicon wafers by applying electrostatic power to internal electrodes.

[0003] In patent document 1 Figure 2 The document describes a workpiece placement apparatus comprising: a wafer chuck for placing a semiconductor wafer; an electrostatic chuck disposed on the wafer chuck; and a focusing ring disposed around the outer periphery of the wafer chuck, surrounding the electrostatic chuck. Additionally, in Patent Document 1… Figure 1 The document describes a workpiece placement device that improves the cooling performance of the focusing ring and enhances the etching characteristics of the outer periphery of the semiconductor wafer, thereby eliminating the time-dependent changes in plasma processing characteristics near the focusing ring and processing the entire surface of the workpiece more uniformly.

[0004] Generally speaking, the demand for semiconductor manufacturing equipment corresponding to deep-machining and microfabrication technologies, used to realize 3D NAND, FinFET structures, etc., is increasing. With the further integration of equipment and the trend towards higher levels of plasma processing, the requirements for electrostatic chucks are also rising. Specifically, to suppress the generation of particles due to wafer contact and slippage, and to ensure resistance to plasma, ceramic materials are selected to hold the wafer in place; dense ceramic sintered bodies are often used. On the other hand, due to technological advancements in semiconductor manufacturing, processes are becoming more complex, requiring high chip yields.

[0005] In the process of manufacturing chips from silicon wafers, the area near the wafer edge contains a relatively large number of chips geometrically, making it an important region for improving the chip yield per unit wafer. On the other hand, because the wafer edge is structurally a singularity, it is also a region with uneven etching rates, which leads to a decrease in chip yield.

[0006] With the further integration of equipment, and the advancement of high-level plasma processing, higher yields are required for the outer periphery of semiconductor wafers.

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2002-033376

[0009] Patent Document 2: Japanese Patent Publication No. 2004-511901 Summary of the Invention

[0010] This invention is based on the understanding of such a problem, and the technical problem to be solved is to provide an electrostatic chuck that can improve the yield of equipment.

[0011] The first invention is an electrostatic chuck comprising: a conductive base plate having a first portion and a second portion disposed on the outer periphery of the first portion, and having a gas inlet path for introducing cooling gas; a first electrostatic chuck portion disposed on the first portion, configured to adsorb a wafer, having a ceramic dielectric substrate having at least one through hole communicating with the gas inlet path and a first adsorption electrode embedded in the ceramic dielectric substrate; and a second electrostatic chuck portion disposed on the second portion, configured to adsorb a focusing ring, having a ceramic layer having at least one through hole for introducing cooling gas, the ceramic layer having at least a first layer that contacts the focusing ring when it is adsorbed onto the second electrostatic chuck portion, the density of the first layer being less than the density of the ceramic dielectric substrate.

[0012] With the increasing sophistication of plasma processing, there is a demand for dense ceramics with low particle size and excellent plasma resistance. However, the inventors have discovered that with the increasing sophistication of plasma processing, the heat input to the plasma processing apparatus increases, with a particularly large amount of heat accumulating in the focusing ring region located at the outer periphery of the wafer, resulting in a decrease in equipment yield. Furthermore, due to the greater thickness of the focusing ring, heat is more easily accumulated at the outer periphery, causing a temperature rise in the outer area and further reducing the equipment yield at the outer periphery of the wafer.

[0013] According to this electrostatic chuck, a first electrostatic chuck portion for adsorbing wafers is constructed using a ceramic dielectric substrate, while a second electrostatic chuck portion for adsorbing a focusing ring is constructed using a ceramic layer, with the density of the ceramic layer being lower than that of the ceramic dielectric substrate. Because the density of the ceramic layer in the second electrostatic chuck portion, corresponding to the outer periphery, is relatively low, the amount of gas supplied to the focusing ring can be increased, and the gas can flow uniformly to the outer periphery. Furthermore, using a ceramic dielectric substrate for the first electrostatic chuck portion ensures low particle count and plasma resistance in the wafer adsorption area, while using a ceramic layer for the second electrostatic chuck portion, by reducing its density (of the porous material), effectively solves the heat problem in the outer periphery, simultaneously achieving low particle count and uniform heat distribution, thereby improving the yield of the equipment.

[0014] The second invention is an electrostatic chuck, in which the ceramic layer further comprises a second layer disposed between the second portion and the first layer, as in the first invention.

[0015] According to this electrostatic chuck, since a second layer is provided between the conductive base plate and the first layer, the thermal effects on the first ceramic layer caused by temperature changes of the base plate are mitigated. Furthermore, if the second layer is made into a high-resistance layer, the first ceramic layer can generate a stable adsorption force at the second electrostatic chuck section, independent of the externally applied high-frequency (RF) base plate used to generate plasma. Additionally, it can suppress insulation damage to the ceramic layer when the base plate is used as the lower electrode and high-frequency power is applied.

[0016] The third invention is an electrostatic chuck in which, in the second invention, the density of the second layer is greater than the density of the first layer.

[0017] According to this electrostatic chuck, since the density of the first layer located on the focusing ring side is relatively low, gas can be efficiently supplied to the upper side of the ceramic layer, further improving the cooling performance of the focusing ring. Additionally, for example, the insulation of the base plate side subjected to applied high-frequency power can be further improved, suppressing insulation breakdown of the second electrostatic chuck portion.

[0018] The fourth invention is an electrostatic chuck in which, in the second invention, the density of the first layer is greater than the density of the second layer.

[0019] According to this electrostatic chuck, by making it into the above structure, while ensuring the plasma resistance of the first layer, the cooling capacity can be ensured because the cooling gas flows actively in the second layer. In addition, since the first layer becomes a quasi-heat relief layer, heat uniformity can be further ensured.

[0020] The fifth invention is an electrostatic chuck in which, in any one of the second to fourth inventions, the first layer has: a first upper surface on the side of the focusing ring; and a first lower surface on the opposite side of the first upper surface; the second layer has: a second upper surface on the side of the first layer; and a second lower surface on the opposite side of the second upper surface; the surface roughness of the first upper surface is less than the surface roughness of the second lower surface.

[0021] According to this electrostatic chuck, by making the surface roughness of the second lower layer relatively large, the second layer can be embedded into the base plate, thereby increasing the contact area with the base plate and improving cooling efficiency. Furthermore, by making the surface roughness of the first upper layer relatively small, the contact area with the focusing ring surface, which has a surface roughness smaller than that of the base plate surface, can be increased, enabling efficient cooling of the focusing ring and more secure adhesion of the focusing ring.

[0022] The sixth invention is an electrostatic chuck in which, in any one of the second to fifth inventions, the first layer and the second layer are arranged to be in contact, and a boundary surface is provided between the first layer and the second layer, wherein the surface roughness of the first layer is less than the surface roughness of the boundary surface.

[0023] According to this electrostatic chuck, by making the surface roughness of the boundary surface relatively large, the contact area on the boundary surface can be increased, thereby improving the cooling efficiency. In addition, by making the surface roughness of the first surface relatively small, the contact area with the focusing ring surface can be increased, thereby enabling efficient cooling of the focusing ring and more secure adsorption of the focusing ring.

[0024] The seventh invention is an electrostatic chuck, wherein in any one of the second to sixth inventions, the second electrostatic chuck portion further comprises a second adsorption electrode built into the ceramic layer, the first layer having: a first upper surface on the focusing ring side; and a first lower surface opposite to the first upper surface, and the second layer having: a second upper surface on the first layer side; and a second lower surface opposite to the second upper surface, the second adsorption electrode being disposed between the first lower surface and the second upper surface, the second adsorption electrode comprising: a second electrode upper surface on the first upper surface side; and a second electrode lower surface opposite to the second electrode upper surface, the surface roughness of the second electrode upper surface being less than the surface roughness of the second electrode lower surface.

[0025] According to this electrostatic chuck, by making the surface roughness of the second electrode relatively small, the thickness deviation of the first layer located on the second adsorption electrode can be reduced, enabling more stable adsorption of the focusing ring. This results in stable and efficient cooling of the focusing ring. On the other hand, since the second adsorption electrode is embedded in the ceramic layer (between the first and second layers), accidents such as peeling may occur due to differences in the thermal expansion coefficients of the materials. By making the surface roughness of the second electrode relatively large, both adhesion to the ceramic layer and cooling efficiency can be achieved simultaneously.

[0026] The eighth invention is an electrostatic chuck, characterized in that, in any one of the first to seventh inventions, the first layer includes a first inner side perpendicular to the side of the first electrostatic chuck portion above and below the first layer and a first outer side opposite to the side of the first inner side, the first outer side being covered by the second layer.

[0027] This electrostatic chuck can simultaneously achieve low particle content, plasma resistance, cooling properties, and uniform heat distribution.

[0028] The ninth invention is an electrostatic chuck, in which the edge region containing the edge portion of the ceramic layer includes the first layer and the second layer, and the proportion of the first layer increases as it gets closer to the upper side of the first layer.

[0029] This electrostatic chuck can simultaneously achieve low particle content, plasma resistance, cooling properties, and uniform heat distribution.

[0030] The tenth invention is an electrostatic chuck, characterized in that, in any one of the inventions from the first to the ninth, the edge portion of the first upper part of the ceramic layer is chamfered.

[0031] This electrostatic chuck can effectively suppress the generation of particles from the outer peripheral edge where the heat load is high.

[0032] According to the present invention, an electrostatic chuck is provided that can improve the yield of equipment. Attached Figure Description

[0033] Figure 1 It is a cross-sectional view of the electrostatic chuck involved in the schematic representation of the implementation method.

[0034] Figure 2 This is a cross-sectional view showing a portion of the electrostatic chuck involved in the embodiment in a stylized and enlarged representation.

[0035] Figure 3 (a) and Figure 3 (b) is a cross-sectional view showing a portion of the electrostatic chuck involved in the embodiment in a patterned and enlarged representation.

[0036] Figure 4 (a) and Figure 4 (b) is a cross-sectional SEM image of the ceramic layer 40 and the ceramic dielectric substrate 30.

[0037] Figure 5 It is a schematic cross-sectional view of a wafer processing apparatus having an electrostatic chuck according to the embodiments.

[0038] Figure 6 This is a cross-sectional view of an electrostatic chuck involved in a modified embodiment of the schematic representation.

[0039] Figure 7 This is a cross-sectional view of a portion of an electrostatic chuck involved in a modified embodiment of the schematic enlargement representation.

[0040] Figure 8 (a) and Figure 8 (b) is a cross-sectional view of a portion of the electrostatic chuck involved in a modified embodiment of the schematic enlarged representation.

[0041] Figure 9This is a cross-sectional view of a wafer processing apparatus with an electrostatic chuck, representing a modified embodiment of the implementation. Detailed Implementation

[0042] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in each drawing, the same reference numerals are used to denote the same constituent elements, and detailed descriptions are omitted where appropriate.

[0043] Figure 1 It is a cross-sectional view of the electrostatic chuck involved in the schematic representation of the implementation method.

[0044] like Figure 1 As shown, the electrostatic chuck 900 includes: a conductive base plate 50; a first electrostatic chuck portion 100 configured to attract a chip W; and a second electrostatic chuck portion 200 configured to attract a focusing ring F.

[0045] The base plate 50 has a first portion 51 and a second portion 52. In the XY plane (described later), the second portion 52 is disposed on the outer periphery of the first portion 51. The second portion 52 is annular. A gas inlet path 53 for introducing cooling gases such as helium is provided in the base plate 50. A first electrostatic chuck portion 100 is provided on the first portion 51, and a second electrostatic chuck portion 200 is provided on the second portion 52.

[0046] In this application specification, the direction from the base plate 50 (part 1 51) toward the first electrostatic chuck portion 100 is defined as the Z-axis direction. One direction orthogonal to the Z-axis direction is called the X-axis direction, and the direction orthogonal to both the Z-axis and X-axis directions is called the Y-axis direction. In this application specification, "in-plane" means, for example, in the XY plane.

[0047] The base plate 50 will be further explained.

[0048] like Figure 1 As shown, the height (Z-axis position) of the upper part of the first section 51 is higher than the height of the upper part of the second surface. The base plate 50 has a stepped shape in which the second section 52 is lower than the first section 51. The second section 52 forms part of the outer periphery P of the electrostatic chuck 900. The first section 51 contains the central C of the electrostatic chuck 900.

[0049] The first electrostatic chuck portion 100 includes a ceramic dielectric substrate 30 and a first adsorption electrode 10. The ceramic dielectric substrate 30 has at least one through hole 35 communicating with the gas inlet passage 53. The first adsorption electrode 10 is embedded in the ceramic dielectric substrate 30.

[0050] The ceramic dielectric substrate 30 has a first main surface 30a on the wafer W side and a second main surface 30b on the opposite side of the first main surface 30a. Through-holes 35 connect to a plurality of grooves 34 provided on the first main surface 30a, through which cooling gas introduced from the gas inlet path 53 is distributed to the first main surface 30a as a whole. A plurality of protrusions 33 are provided on the first main surface 30a. When a voltage is applied to the first adsorption electrode 10, the wafer W is adsorbed and held in the first electrostatic chuck portion 100 by the protrusions 33.

[0051] The second electrostatic chuck portion 200 includes a ceramic layer 40 and a second adsorption electrode 20. The ceramic layer 40 has at least one through hole 45 communicating with the gas inlet passage 53. The second adsorption electrode 20 is embedded in the ceramic layer 40.

[0052] The ceramic layer 40 has at least a first layer 41 that contacts the focusing ring F when it is adsorbed onto the second electrostatic chuck portion 200. The first layer 41 has a first upper surface 41u on the side of the focusing ring F and a first lower surface 41b on the opposite side of the first upper surface 41u. The second adsorption electrode 20 has a second electrode upper surface 20u on the side of the first upper surface 41u and a second electrode lower surface 20b on the opposite side of the second electrode upper surface 20u. When a voltage is applied to the second adsorption electrode 20, the focusing ring F is adsorbed and held onto the second electrostatic chuck portion 200 by the first upper surface 41u.

[0053] In the electrostatic chuck 900, the density of the first layer 41 of the ceramic layer 40 is less than that of the ceramic dielectric substrate 30. That is, the first layer 41 is rougher than the ceramic dielectric substrate 30. With the increasing sophistication of plasma processing, there is a demand for dense ceramics with low particle size and excellent plasma resistance. On the other hand, the inventors have discovered that with the increasing sophistication of plasma processing, the heat input to the plasma processing apparatus increases, especially the heat accumulation in the focusing ring portion located at the outer periphery of the wafer, resulting in a decrease in the yield of the equipment. In addition, since the focusing ring is thicker, heat is more likely to accumulate at the outer periphery, causing the temperature of the outer periphery to rise, resulting in a decrease in the yield of the equipment at the outer periphery of the wafer.

[0054] Therefore, in the electrostatic chuck 900, because the density of the ceramic layer 40 in the second electrostatic chuck section 200, which corresponds to the outer periphery, is relatively low, the amount of gas supplied to the focusing ring F can be increased, and the gas can be made to flow evenly to the outer periphery. That is, by using a ceramic dielectric substrate 30 to form the first electrostatic chuck section 100 to ensure low particle size and plasma resistance in the wafer adsorption area, and by using the ceramic layer 40 to form the second electrostatic chuck section 200, the density can be reduced, for example, by making it a porous layer, which can effectively solve the heat problem in the outer periphery, and can simultaneously achieve low particle size and uniform heat, thereby improving the yield of the equipment.

[0055] To improve the chip yield per unit wafer, it is necessary to control the etching rate near the edge and increase the number of qualified chips near the edge. To further improve the chip yield near the edge, a method and structure are needed to uniformize the etching state across the span from the wafer center to the edge, i.e., the etching state in the radial direction.

[0056] The following technique has been used since the beginning of the year as a method and structure to homogenize the etching state near the wafer edge: a ring-shaped component called a focusing ring is arranged on the outer periphery of the wafer to homogenize the plasma environment between the central and outer periphery of the wafer during the etching process, thereby suppressing etching deviations. One example of a method to suppress etching deviations is to homogenize the etching state near the wafer edge by using temperature control in the edge ring region.

[0057] In the electrostatic chuck 900, through a simple method and structure, it is possible to simultaneously ensure the particle resistance of the wafer W portion, which is directly exposed to high-density plasma, and the uniform heating of the focusing ring F portion.

[0058] In the electrostatic chuck 900, by providing a second electrostatic chuck section 200, the focusing ring F is firmly attached to the electrostatic adsorption surface (first upper surface 41u) using a high electrostatic adsorption force, thereby ensuring high heat transfer and effectively cooling the outer peripheral parts, especially where heat tends to accumulate. Furthermore, by reducing the density of the electrostatic adsorption surface (first upper surface 41u), for example by making it a porous layer, a large flow rate of cooling gas (such as He gas) can be circulated with lower pressure drop through a simpler method and structure, achieving higher heat exchange efficiency.

[0059] Furthermore, grooves or protrusions (dots) (not shown) may be provided on the surface of ceramic layer 40 (first upper layer 41u).

[0060] The method for evaluating the density of the ceramic layer 40 and the ceramic dielectric substrate 30 is described.

[0061] Cross-sectional images of the ceramic layer 40 and the ceramic dielectric substrate 30 were obtained. Scanning Electron Microscope (SEM) was used to acquire the images. Taking the ceramic layer 40 as an example, the second electrostatic chuck portion 200 was cut to include the cross-section of the ceramic layer 40, and the sample cross-section was resin-embedded and then mechanically ground. Specifically, a test piece was selected to include the ceramic layer 40 and pass through it in the Z-axis direction. Selection methods included, for example, spiral machining or high-pressure water jet cutting. Alternatively, an observation cross-section could be created using ion beam milling. Grinding was performed until a mirror-like surface appeared on the cross-section of the test piece, and the sample was subjected to Pt vapor deposition before SEM observation. The magnification was set to approximately 200–3000x (500x as an example) to allow for appropriate observation of the cross-sectional structure, and the accelerating voltage was set to approximately 5kV–15kV. Five fields of view were observed to control for deviations. When it is difficult to visually determine the density of the first layer 41 and the ceramic dielectric substrate 30, these observed images are analyzed using the commercially available 2D image analysis software "Win Roof," allowing for the calculation of porosity and comparison of their relative densities. Lower porosity indicates higher density. The calculated porosity is then used as the average value across 5 fields of view. The density of the ceramic dielectric substrate 30 can be evaluated in the same way.

[0062] Figure 4 (a) and Figure 4 (b) is a cross-sectional SEM image of the ceramic layer 40 and the ceramic dielectric substrate 30. (The images are shown separately.) Figure 4 (a) Corresponding to ceramic layer 40 (layer 1 41), Figure 4 (b) Corresponding to ceramic dielectric substrate 30.

[0063] like Figure 4 As shown in (a) and (b), in this example, it was visually determined that the density of the first layer 41 was less than that of the ceramic dielectric substrate 30.

[0064] Figure 2 This is a cross-sectional view showing a portion of the electrostatic chuck involved in the embodiment in a stylized and enlarged representation.

[0065] Figure 2 This is an enlarged view of the second electrostatic chuck section 200.

[0066] exist Figure 2In the example shown, the ceramic layer 40 further includes a second layer 42 disposed between the second portion 52 of the base plate 50 and the first layer 41. The second layer 42 has a second upper surface 42u on the side of the first layer 41 and a second lower surface 42b on the opposite side of the second upper surface 42u. In this example, the second adsorption electrode 20 is disposed between the first layer 41 and the second layer 42. More specifically, the second adsorption electrode 20 is disposed between the first lower surface 41b and the second upper surface 42u. Furthermore, the adsorption electrode 20 can also be built into the first layer 41, that is, the second adsorption electrode 20 can also be disposed between the first upper surface 41u and the first lower surface 41b.

[0067] In this example, at least a portion of the first layer 41 is configured to contact the second layer 42, and a boundary surface B is provided between the first layer 41 and the second layer 42. Specifically, at least a portion of the second upper layer 42u is configured to contact the first lower layer 41b. Furthermore, other layers may be provided between the first layer 41 and the second layer 42.

[0068] In the electrostatic chuck 900, since a second layer 42 is provided between the conductive base plate 50 and the first layer 41, the thermal effects on the first layer 41 of the ceramic layer 40 caused by temperature changes of the base plate 50 are mitigated. Furthermore, if the second layer 42 is made into a high-resistance layer, the first layer 41 of the ceramic layer 40 is electrically independent of the externally applied high-frequency (RF) power from the base plate 50 used to generate plasma, and a stable adsorption force can be achieved in the second electrostatic chuck section 200. Additionally, it can suppress insulation damage to the ceramic layer 40 when the base plate 50 is used as the lower electrode and high-frequency power is applied.

[0069] The base plate 50 is made of metals such as aluminum or aluminum alloy.

[0070] The ceramic dielectric substrate 30 is, for example, a flat substrate formed from sintered ceramic. For example, the ceramic dielectric substrate 30 contains alumina (Al₂O₃). High-insulation materials such as alumina, yttrium oxide, aluminum nitride, and boron nitride can be used as the ceramic dielectric substrate. For example, the ceramic dielectric substrate 30 is formed from high-purity alumina. The concentration of alumina in the ceramic dielectric substrate 30 is, for example, 90% by mass or more and 100% by mass or less, preferably 95% by mass or more and 100% by mass or less, more preferably 99% by mass or more and 100% by mass or less. By using high-purity alumina, the plasma resistance of the ceramic dielectric substrate 30 can be improved. Furthermore, the concentration of alumina can be determined by fluorescence X-ray analysis or the like.

[0071] In the ceramic layer 40, the first layer 41 is, for example, a ceramic dielectric layer. Specifically, compounds in which other metal oxides are added to ceramics such as alumina or aluminum nitride can be used. For example, compounds in which titanium oxide is added to alumina are preferred. As an example, the first layer 41 is a ceramic spray-coated film.

[0072] In the ceramic layer 40, the second layer 42 is, for example, a ceramic insulating layer. The second layer 42 contains, for example, at least one of alumina, yttrium oxide, aluminum nitride, and boron nitride. Preferably, it is composed of alumina. As an example, the second layer 42 is a ceramic-sprayed film. The second layer 42 can also be an alumina film layer formed by anodizing the base plate 50 made of aluminum.

[0073] In the electrostatic chuck 900, the density of the second layer 42 of the ceramic layer 40 is, for example, greater than the density of the first layer 41. That is, in the ceramic layer 40, as an example, the second layer 42 located on the base plate 50 side is denser than the first layer 41. Since the density of the first layer 41 located on the focusing ring F side is relatively small, gas can be efficiently supplied to the upper side of the ceramic layer 40, which can further improve the cooling performance of the focusing ring F. In addition, for example, the insulation of the base plate 50 side with applied high-frequency power can be further improved, and insulation breakdown of the second electrostatic chuck portion 200 can be suppressed.

[0074] In the electrostatic chuck 900, the density of the first layer 41 of the ceramic layer 40 is, for example, greater than that of the second layer 42. That is, in the ceramic layer 40, as an example, the first layer 41 located on the focusing ring F side is denser than the second layer 42. Therefore, while ensuring the plasma resistance of the first layer 41, cooling capacity can be ensured because the cooling gas actively flows in the second layer 42. In addition, since the first layer 41 serves as a quasi-heat relief layer, heat uniformity can be further ensured.

[0075] Next, the thickness relationship between the ceramic layer 40 (layer 1 41, layer 2 42) and the ceramic dielectric substrate 30 in the electrostatic chuck 900 will be described. Here, "thickness" refers to the length of the constituent elements such as layer 1 41 along the Z-axis.

[0076] The thickness of the first layer 41 is, for example, less than the thickness of the ceramic dielectric substrate 30. That is, the first layer 41 is thinner than the ceramic dielectric substrate 30. Therefore, since the ceramic layer 40 (first layer 41) of the second electrostatic chuck portion 200, which is located on the outer peripheral side (second part 52) ​​where heat is more likely to accumulate, is relatively thin, the focusing ring F can be cooled effectively.

[0077] Next, the surface roughness relationship between the ceramic layer 40 (layer 1 41, layer 2 42) and the second adsorption electrode 20 in the electrostatic chuck 900 will be described.

[0078] Here, "surface roughness" refers, for example, to the arithmetic mean roughness (Ra), which can be calculated using the method described below. Here, an example of the first upper surface 41u and the second lower surface 42b of the ceramic layer 40 will be explained. A test piece is cut out including the first upper surface 41u and the second lower surface 42b, the resin-embedded test piece is ground, and then observed using a SEM (Scanning Electron Microscope). From SEM images taken at 100 to 1000x magnification, the arithmetic mean roughness Ra is calculated using the method based on Japanese Industrial Standard JIS B 0601:2013. Furthermore, the surface roughness Ra-2b of the second lower surface 42b is calculated using a contour curve that mimics the interface between the second lower surface 42b and the second part 52 of the base plate 50.

[0079] In the electrostatic chuck 900, for example, the surface roughness Ra-1u of the first upper layer 41u is smaller than the surface roughness Ra-2b of the second lower layer 42b. By making the surface roughness of the second lower layer 42b relatively large, the second layer 42 can be embedded into the base plate 50, thereby increasing the contact area with the base plate 50 and improving cooling efficiency. Furthermore, since the surface roughness of the first upper layer 41u is relatively small, the contact area with the focusing ring F, whose surface roughness is smaller than that of the base plate 50, can be increased, enabling efficient cooling of the focusing ring F and more secure adhesion of the focusing ring F.

[0080] In the electrostatic chuck 900, for example, the surface roughness Ra-1u of the first upper layer 41u is smaller than the surface roughness Ra-B of the boundary surface B between the first layer 41 and the second layer 42. By making the surface roughness of the boundary surface B relatively large, the contact area on the boundary surface B can be increased, thereby improving cooling efficiency. In addition, since the surface roughness of the first upper layer 41u is relatively small, the contact area with the surface of the focusing ring F can be increased, enabling efficient cooling of the focusing ring F and more secure adhesion of the focusing ring F.

[0081] In the electrostatic chuck 900, for example, the surface roughness of the upper 20u of the second electrode is smaller than the surface roughness of the lower 20b of the second electrode. Because the surface roughness of the upper 20u of the second electrode is relatively small, the thickness deviation of the first layer 41 located on the second adsorption electrode 20 can be reduced, increasing the contact area with the surface of the focusing ring F. This allows for more stable adsorption of the focusing ring F, resulting in stable and efficient cooling of the focusing ring F. On the other hand, since the second adsorption electrode 20 is embedded in the ceramic layer 40 (between the first layer 41 and the second layer 42), accidents such as peeling may occur due to differences in the thermal expansion coefficients of the materials. Because the surface roughness of the lower 20b of the second electrode is relatively large, both good adhesion to the ceramic layer 40 and efficient cooling can be achieved simultaneously.

[0082] Figure 3 (a) and Figure 3 (b) is a cross-sectional view showing a portion of the electrostatic chuck involved in the embodiment in a patterned and enlarged representation.

[0083] use Figure 3 (a) and Figure 3 (b) A modified example of the edge region E containing the edge portion 40e of the ceramic layer 40 will be described.

[0084] like Figure 3 As shown in (a), in the electrostatic chuck 900, for example, the first layer 41 includes a first inner surface 41i perpendicular to the first electrostatic chuck portion 100 side perpendicular to the first upper layer 41u and the first lower layer 41b. Figure 2 (Refer to) and the first outer side 41o on the opposite side of the first inner side 41i, the first outer side 41o being covered by the second layer 42.

[0085] like Figure 3 As shown in (b), in the electrostatic chuck 900, for example, a portion of the first outer surface 41o may be covered by the second layer 42. In this example, the edge region E containing the edge portion 40e of the ceramic layer 40 includes the first layer 41 and the second layer 42, with the proportion of the first layer 41 increasing as it approaches the first upper surface 41u. That is, the second layer 42 covers the first outer surface 41o in a state of inward inclination along the span from the first upper surface 41u to the first lower surface 41b.

[0086] exist Figure 3 The electrostatic chuck 900 shown in (a) and (b) can simultaneously achieve low particle content, plasma resistance, cooling, and heat uniformity.

[0087] Here, the edge portion 40e is the part of the ceramic layer 40 that contacts the outer surface. Figure 2 In the example, the part where the first upper surface 41u contacts the first outer surface 41o is the edge portion 40e. The edge region E refers to the region that includes the edge portion 40e.

[0088] Furthermore, the first inner surface 41i can also be covered by the second layer 42. As a result, the current path to the base plate 50 is cut off, the applied voltage to the first layer 41 tends to stabilize, and the adsorption force tends to stabilize.

[0089] Figure 3 In (b), the edge 40e of, for example, the first upper surface 41 of the ceramic layer 40 can also be chamfered (not shown). Therefore, it is possible to effectively suppress the generation of particles from the outer peripheral edge where the heat load is high.

[0090] Refer again Figure 1 Further explanation of the electrostatic chuck 900.

[0091] The ceramic dielectric substrate 30 has a first main surface 30a and a second main surface 30b. The first main surface 30a is the surface on which the adsorbed object, i.e., the wafer W, is placed. The second main surface 30b is the surface opposite to the first main surface 30a. The adsorbed object, i.e., the wafer W, is, for example, a semiconductor substrate such as a silicon wafer.

[0092] A first adsorption electrode 10 is disposed inside the ceramic dielectric substrate 30. The first adsorption electrode 10 is disposed between the first main surface 30a and the second main surface 30b in the Z-axis direction. That is, the first adsorption electrode 10 is disposed in such a way that it is inserted into the ceramic dielectric substrate 30. For example, the first adsorption electrode 10 can also be integrally sintered into the ceramic dielectric substrate 30.

[0093] The first adsorption electrode 10 is in the shape of a thin film oriented along the first main surface 30a and the second main surface 30b of the ceramic dielectric substrate 30.

[0094] The first adsorption electrode 10 is connected to the adsorption power supply. Figure 5 The adsorption power supply 505. In the first electrostatic chuck section 100, by applying a voltage (adsorption voltage) to the first adsorption electrode 10 from the adsorption power supply, a charge is generated on the first main surface 30a side of the first adsorption electrode 10, and the object, i.e., the wafer W, is adsorbed and held by electrostatic force. The adsorption power supply supplies direct current (DC) or alternating current (AC) to the first adsorption electrode 10. The adsorption power supply is, for example, a DC power supply. The adsorption power supply can also be, for example, an AC power supply.

[0095] The first adsorption electrode 10 is, for example, made of metal. The first adsorption electrode 10 contains, for example, at least one of Ag, Pd, Pt, Mo, and W. The first adsorption electrode 10 may also contain, for example, metal and ceramic.

[0096] The ceramic layer 40 has a third main surface 40a and a fourth main surface 40b. The third main surface 40a is the surface on which the adsorption target, i.e., the focusing ring F, is placed. The fourth main surface 40b is the surface opposite to the third main surface 40a. The adsorption target, i.e., the focusing ring F, contains, for example, silicon (Si) or silicon carbide (SiC). As described above, when the ceramic layer 40 has a first layer 41 and a second layer 42, the first upper layer 41u constitutes the third main surface 40a, and the second lower layer 42b constitutes the fourth main surface 40b.

[0097] like Figure 1 As shown, in this example, the third main surface 40a is located closer to the lower side in the Z-axis direction than the second main surface 30b of the ceramic dielectric substrate 30.

[0098] In this example, a second adsorption electrode 20 is disposed inside the ceramic layer 40. The second adsorption electrode 20 is disposed between the third main surface 40a and the fourth main surface 40b in the Z-axis direction. That is, the second adsorption electrode 20 is disposed in a manner that it is inserted into the ceramic layer 40. For example, the second adsorption electrode 20 can also be embedded in the ceramic layer 40 by means of sputtering, printing, CVD, PVD, etc.

[0099] The second adsorption electrode 20 is in the shape of a thin film oriented along the third main surface 40a and the fourth main surface 40b of the ceramic layer 40.

[0100] The second adsorption electrode 20 is connected to the adsorption power supply. Figure 5 The adsorption power supply 506. In the second electrostatic chuck section 200, by applying a voltage (adsorption voltage) to the second adsorption electrode 20 from the adsorption power supply, a charge is generated on the third main surface 40a side of the second adsorption electrode 20, and the object, i.e., the focusing ring F, is adsorbed and held by electrostatic force. The adsorption power supply supplies direct current (DC) or alternating current (AC) to the second adsorption electrode 20. The adsorption power supply is, for example, a DC power supply. The adsorption power supply can also be, for example, an AC power supply.

[0101] The power supply used for the first adsorption electrode 10 and the power supply used for the second adsorption electrode 20 can be different or the same.

[0102] The second adsorption electrode 20 is, for example, made of metal. The second adsorption electrode 20 may contain at least one of Ag, Pd, Pt, Mo, and W. The second adsorption electrode 20 may also contain metal and ceramic, for example.

[0103] When the first adsorption electrode 10 contains metal and ceramic and the second adsorption electrode 20 contains metal and ceramic, the ratio of the total metal volume of the metal volume and ceramic volume contained in the first adsorption electrode 10 to the ratio of the total metal volume of the metal volume and ceramic volume contained in the second adsorption electrode 20 can be the same or different.

[0104] The first adsorption electrode 10 is provided with a connecting portion 81 extending toward the second main surface 30b of the ceramic dielectric substrate 30. The connecting portion 81 is, for example, a via (solid type) or a via hole (hollow type) that is conductive to the first adsorption electrode 10. The connecting portion 81 can also be a metal terminal connected by a suitable method such as brazing.

[0105] The second adsorption electrode 20 has a connecting portion 82 extending toward the fourth main surface 40b of the ceramic layer 40. The connecting portion 82 is, for example, a via (solid type) or a via hole (hollow type) that is conductive to the second adsorption electrode 20. The connecting portion 82 can also be a metal terminal connected by a suitable method such as brazing. Alternatively, the connecting portion 82 can also be formed by spray plating.

[0106] The connecting part 82 can also be configured to electrically connect the second adsorption electrode 20 and the base plate 50, and the power supply for adsorption ( Figure 5 The adsorption power supply (506) is connected to the base plate.

[0107] For example, in the ceramic layer 40, a third layer (not shown) that contacts the second adsorption electrode 20 may be provided between the first layer 41 and the second layer 42, and the third layer is configured to contact the connecting portion 82.

[0108] The base plate 50 is, for example, a component that supports the ceramic dielectric substrate 30. The ceramic dielectric substrate 30 is fixed to the base plate 50 by an adhesive member 60. As the adhesive member 60, for example, a silicone adhesive is used.

[0109] The base plate 50 is, for example, divided into an upper part 50a and a lower part 50b, and a connecting path 55 is provided between the upper part 50a and the lower part 50b. One end of the connecting path 55 is connected to the input path 56, and the other end of the connecting path 55 is connected to the output path 57.

[0110] The base plate 50 also functions to regulate the temperature of the first electrostatic chuck section 100 and the second electrostatic chuck section 200. For example, when cooling the first electrostatic chuck section 100 and the second electrostatic chuck section 200, a cooling medium such as helium flows in from the input path 56, passes through the connecting path 55, and flows out from the output path 57. Thus, by absorbing heat from the base plate 50 through the cooling medium, the ceramic dielectric substrate 30 and ceramic layer 40 mounted thereon can be cooled. On the other hand, when heat preservation is needed for the first electrostatic chuck section 100 and the second electrostatic chuck section 200, a heat preservation medium can be placed into the connecting path 55. A heating element can also be built into the ceramic dielectric substrate 30, the ceramic layer 40, and the base plate 50. By adjusting the temperature of the base plate 50, the ceramic dielectric substrate 30, and the ceramic layer 40, the temperature of the object held by the first electrostatic chuck section 100 (i.e., the wafer W) and / or the object held by the second electrostatic chuck section 200 (i.e., the focusing ring F) can be adjusted.

[0111] As previously described, in this example, a groove 34 is provided on the first main surface 30a side of the ceramic dielectric substrate 30. The groove 34 is recessed in the direction (Z-axis direction) from the first main surface 30a toward the second main surface 30b and extends continuously in the XY plane. If the portion without the groove 34 is used as a protrusion 33, the object, i.e., the wafer W, is placed on the protrusion 33. The first main surface 30a is the surface that contacts the back side of the object, i.e., the wafer W. That is, the first main surface 30a is the plane including the surface above the protrusion 33. A space is formed between the back side of the object, i.e., the wafer W, placed on the first electrostatic chuck portion 100 and the groove 34.

[0112] The ceramic dielectric substrate 30 has a through hole 35 connected to the groove 34. The through hole 35 is provided across the span from the second main surface 30b to the first main surface 30a. That is, the through hole 35 extends in the Z-axis direction from the second main surface 30b to the first main surface 30a and passes through the ceramic dielectric substrate 30.

[0113] By appropriately selecting the height of the protrusion 33 (the depth of the groove 34) and the area ratio and shape of the protrusion 33 and the groove 34, the temperature of the object, i.e., the wafer W, and the particles attached to the wafer W can be controlled in an optimal state.

[0114] A gas inlet path 53 is provided on the base plate 50. The gas inlet path 53 may, for example, be configured to pass through the base plate 50. Alternatively, the gas inlet path 53 may not pass through the base plate 50 and may branch off from other gas inlet paths 53 to the ceramic dielectric substrate 30 side. Furthermore, the gas inlet path 53 may be provided at multiple locations on the base plate 50.

[0115] The gas inlet path 53 is connected to the through hole 35. That is, the heat transfer gas (helium (He) etc.) flowing into the gas inlet path 53 flows into the through hole 35 after passing through the gas inlet path 53.

[0116] The heat transfer gas flowing into the through-hole 35 then flows into the space between the object, i.e., the wafer W, and the slot 34. Thus, the wafer W can be directly cooled using the heat transfer gas.

[0117] The ceramic layer 40 has a through hole 45. The through hole 45 is provided across the span from the fourth main surface 40b to the third main surface 40a. That is, the through hole 45 extends in the Z-axis direction from the fourth main surface 40b to the third main surface 40a and passes through the ceramic layer 40. Similar to the first electrostatic chuck portion 100, even in the second electrostatic chuck portion 200, the gas inlet passage 53 is connected to the through hole 45. That is, the heat transfer gas (helium (He) etc.) flowing into the gas inlet passage 53 flows into the through hole 45 after passing through the gas inlet passage 53.

[0118] The heat transfer gas flowing into the through-hole 45 directly cools the object, i.e., the focusing ring F, after passing through the through-hole 45. In the electrostatic chuck 900, when the first layer 41 is formed, for example, by spraying, its low density allows the heat transfer gas to diffuse within the first layer 41. Therefore, the heat transfer gas can flow over the entire first surface 41u of the first layer 41, enabling more efficient cooling of the focusing ring F.

[0119] The thickness of the first adsorption electrode 10 is, for example, 1 μm to 100 μm. The thickness of the second adsorption electrode 20 is, for example, 1 μm to 100 μm. The thickness of the second adsorption electrode 20 may also be, for example, greater than the thickness of the first adsorption electrode 10. The second adsorption electrode 20 may also be used, for example, as a high-frequency electrode (RF electrode) for generating plasma.

[0120] Here, the thickness of the first adsorption electrode 10 and / or the second adsorption electrode 20 refers to the length of the first adsorption electrode 10 and / or the second adsorption electrode 20 in the Z-axis direction.

[0121] The manufacturing method of the second electrostatic chuck section 200 will be described below.

[0122] On the second portion 52 of the base plate 50, a second layer 42 is formed, for example, by spraying. The second layer 42 is, for example, an Al2O3 layer. The thickness of the second layer 42 is, for example, 50 μm to 5000 μm. Next, a second adsorption electrode 20 is formed, for example, by spraying. Next, a first layer 41 is formed, for example, by spraying. The first layer 41 is, for example, an Al2O3-TiO2 layer. The amount of TiO2 added is, for example, 1 wt% to 15 wt%. The thickness of the first layer 41 is, for example, 50 to 500 μm.

[0123] Alternatively, after the second electrostatic chuck portion 200 is formed, the first electrostatic chuck portion 100 can be disposed on the first portion 51 of the base plate 50 via the adhesive member 60.

[0124] The first adsorption electrode 10 is formed, for example, by screen printing, coating (spin coating, plating, inkjet printing, dispensing, etc.), vapor deposition, etc. For example, the first adsorption electrode 10 can be formed by stacking each layer multiple times with the first main surface 30a facing downwards.

[0125] Figure 5 This is a schematic cross-sectional view of a wafer processing apparatus having the electrostatic chuck 900 according to the embodiment.

[0126] like Figure 5As shown, the wafer processing apparatus 500 includes a processing container 501, a high-frequency power supply 504, an adsorption power supply 505, an upper electrode 510, and an electrostatic chuck 900. A processing gas inlet 502 for introducing processing gas and an upper electrode 510 are provided on the top surface of the processing container 501. An exhaust port 503 for depressurizing and venting the interior is provided on the bottom plate of the processing container 501. A first electrostatic chuck portion 100 is disposed inside the processing container 501 below the upper electrode 510. In the first electrostatic chuck portion 100, a first adsorption electrode 10 is connected to the adsorption power supply 505. In the second electrostatic chuck portion 200, a second adsorption electrode 20 is connected to the adsorption power supply 506.

[0127] When a voltage (high-frequency voltage) is applied to the base plate 50 and the upper electrode 510 from the high-frequency power supply 504, a high-frequency discharge is generated, and the processing gas introduced into the processing container 501 is excited and activated by the plasma, thereby processing the object, i.e., the wafer W.

[0128] When an adsorption voltage (adsorption voltage) is applied to the first adsorption electrode 10 from the adsorption power supply 505, a charge is generated on the first main surface 30a side of the first adsorption electrode 10, and the object, i.e., the wafer W, is adsorbed and held in the first electrostatic chuck portion 100 by electrostatic force. When an adsorption voltage (adsorption voltage) is applied to the second adsorption electrode 20 from the adsorption power supply 506, a charge is generated on the third main surface 40a side of the second adsorption electrode 20, and the object, i.e., the focusing ring F, is adsorbed and held in the second electrostatic chuck portion 200 by electrostatic force.

[0129] Figure 6 This is a cross-sectional view of an electrostatic chuck involved in a modified embodiment of the schematic representation.

[0130] Figure 7 This is a cross-sectional view of a portion of an electrostatic chuck involved in a modified embodiment of the schematic enlargement representation.

[0131] Figure 8 (a) and Figure 8 (b) is a cross-sectional view of a portion of the electrostatic chuck involved in a modified embodiment of the schematic enlarged representation.

[0132] Figure 9 This is a cross-sectional view of a wafer processing apparatus with an electrostatic chuck, representing a modified embodiment of the implementation.

[0133] like Figure 6 , Figure 7 , Figure 8 (a) Figure 8 (b) Figure 9As shown, in the electrostatic chuck 900A of the modified embodiment, the second adsorption electrode 20 in the ceramic layer 40 is omitted. The ceramic layer 40 has a first layer 41 and a second layer 42, which are arranged to be in direct contact through a boundary surface B.

[0134] In this example, the base plate 50 serves as the adsorption electrode for the focusing ring F. More specifically, the base plate 50 is connected to the adsorption power supply ( Figure 9 (Adsorption power supply 506). In the second electrostatic chuck section 200, by applying a voltage (adsorption voltage) to the base plate 50 from the adsorption power supply, an electric charge is generated on the surface of the fourth main surface 40b side of the base plate 50, and the object, i.e. the focusing ring F, is adsorbed and held by electrostatic force.

[0135] The power supply used for the first adsorption electrode 10 and the power supply used for the base plate 50 can be different or the same.

[0136] Since the electrostatic chuck 900A involved in the modified embodiment omits the second adsorption electrode 20 and uses the base plate 50 as the adsorption electrode for the focusing ring F, it is substantially the same as the electrostatic chuck 900 involved in the above embodiment, so the description of other parts is omitted.

[0137] Even in the electrostatic chuck 900A described in the modified embodiment, a second layer 42 is provided between the conductive base plate 50 and the first layer 41. Therefore, for example, the first layer 41 of the ceramic layer 40 is independent of the externally applied high-frequency (RF) power to generate plasma from the base plate 50. Thus, the effect of temperature changes in the base plate 50 on the ceramic layer 40 is mitigated, and a stable adsorption force can be achieved in the second electrostatic chuck portion 200. In addition, for example, insulation damage to the ceramic layer 40 can be suppressed when the base plate 50 is used as the lower electrode and high-frequency power is applied.

[0138] As explained above, according to the embodiments, an electrostatic chuck can be provided that can improve the yield of equipment.

[0139] The embodiments of the present invention have been described above. However, the present invention is not limited to the above description. Regarding the foregoing embodiments, any design modifications made by those skilled in the art that possess the features of the present invention are also included within the scope of the present invention. For example, the shape, size, material, configuration, and arrangement of the various elements of the electrostatic chuck are not limited to the illustrated descriptions, but can be appropriately modified. Furthermore, as long as it is technically feasible, the various elements of the foregoing embodiments can be combined, and any resulting technology that includes the features of the present invention is also included within the scope of the present invention.

Claims

1. An electrostatic chuck, comprising: A conductive base plate has a first part and a second part disposed on the outer periphery of the first part, and is provided with a gas inlet path for introducing cooling gas; The first electrostatic chuck portion is disposed on the first part and is configured to adsorb a chip, having a ceramic dielectric substrate having at least one through hole communicating with the gas inlet path and a first adsorption electrode built into the ceramic dielectric substrate. The second electrostatic chuck portion is disposed on the second part and configured as a focusing ring capable of adsorbing and focusing. It has a ceramic layer with at least one through-hole for introducing cooling gas. Its characteristic is that... The ceramic layer has at least a first layer that contacts the focusing ring when it is adsorbed onto the second electrostatic chuck portion, and a second layer disposed between the second portion and the first layer. The density of the first layer is configured to be less than that of the ceramic dielectric substrate. The first layer has: a first upper surface on the side of the focusing ring; and a first lower surface on the opposite side of the first upper surface. The second layer has: a second upper surface on the side of the first layer; and a second lower surface on the opposite side of the second upper surface. The surface roughness of the first surface is less than that of the second surface.

2. The electrostatic chuck according to claim 1, characterized in that, The density of the second layer is greater than that of the first layer.

3. The electrostatic chuck according to claim 1, characterized in that, The density of the first layer is greater than that of the second layer.

4. The electrostatic chuck according to any one of claims 1 to 3, characterized in that, The first layer and the second layer are arranged in contact, and a boundary surface is provided between the first layer and the second layer. The surface roughness of the first layer is less than the surface roughness of the boundary surface.

5. The electrostatic chuck according to any one of claims 1 to 3, characterized in that, The second electrostatic chuck portion also includes a second adsorption electrode built into the ceramic layer. The first layer has: a first upper surface on the side of the focusing ring; and a first lower surface on the opposite side of the first upper surface. The second layer has: a second upper surface on the side of the first layer; and a second lower surface on the opposite side of the second upper surface. The second adsorption electrode is disposed between the lower part of the first electrode and the upper part of the second electrode. The second adsorption electrode comprises: a second electrode surface on the upper side of the first electrode; and a second electrode surface on the opposite side of the second electrode surface. The surface roughness of the upper part of the second electrode is less than the surface roughness of the lower part of the second electrode.

6. The electrostatic chuck according to any one of claims 1 to 3, characterized in that, The first layer includes a first inner side perpendicular to the first electrostatic chuck portion side above and below the first layer, and a first outer side opposite to the first inner side. The first outer surface is covered by the second layer.

7. The electrostatic chuck according to claim 6, characterized in that, The edge region containing the edge portion of the ceramic layer includes the first layer and the second layer, and the proportion of the first layer increases as it gets closer to the upper side of the first layer.

8. The electrostatic chuck according to any one of claims 1 to 3, characterized in that, In the ceramic layer, the upper edge of the first layer is chamfered.

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