Electrostatic chuck, substrate fixing device, and method for manufacturing electrostatic chuck

Abstract

An electrostatic chuck includes an adsorption portion that adsorbs and holds an object to be adsorbed, and a heating portion stacked on the adsorption portion. The heating portion includes a first layer comprising a first heating element. The heating portion includes a second layer stacked on the first layer and comprising a second heating element and a connection pattern electrically connected to the first heating element. The heating portion includes a third layer stacked on the second layer and comprising a power supply portion electrically connected to the connection pattern. The first heating element includes a plurality of heating elements arranged independently for each of a plurality of zones. The second heating element and the connection pattern are installed on the same plane. The electrical resistivity of the connection pattern is lower than the electrical resistivity of the second heating element.

Description

Technology Field

[0001] The present invention relates to an electrostatic chuck, a substrate fixing device, and a method for manufacturing an electrostatic chuck. Background Technology

[0002] In the relevant technology, a film deposition device and a plasma etching device used when manufacturing semiconductor devices have a stage for accurately holding a substrate, such as a silicon wafer, within a vacuum processing chamber. As such a stage, a substrate fixing device is proposed that holds the substrate by adsorbing it using an electrostatic chuck mounted on a base plate (see, for example, Patent Document 1). An electrode for adsorbing the substrate and a heating element for controlling the temperature of the substrate are embedded in the substrate fixing device. Prior art literature

[0003] Japanese Patent Application Publication No. 2020-88304 The problem to be solved

[0004] However, in the aforementioned substrate fixing device, non-uniformity of heat generation density may occur on the substrate mounting surface of the electrostatic chuck that adsorbs the substrate. Non-uniformity of heat generation density causes non-uniformity of temperature on the substrate. Non-uniformity of substrate temperature causes, for example, non-uniformity of the etching rate in a plasma etching device, and consequently becomes a factor that lowers the yield of the semiconductor device. Therefore, improvement of temperature uniformity on the substrate mounting surface of the electrostatic chuck is required. means of solving the problem

[0005] According to a first embodiment of the present invention, an electrostatic chuck is provided, wherein the electrostatic chuck comprises an adsorption portion configured to adsorb and maintain an object to be adsorbed, and a heating portion stacked on the adsorption portion, wherein the heating portion comprises a first layer including a first heating element, a second layer stacked on the first layer including a second heating element and a connection pattern electrically connected to the first heating element, and a third layer stacked on the second layer including a power supply portion electrically connected to the connection pattern, wherein the first heating element includes a plurality of heating elements independently arranged for each of a plurality of zones, and the second heating element and the connection pattern are installed on the same plane, and the electrical resistivity of the connection pattern is lower than the electrical resistivity of the second heating element. Effects of the invention

[0006] According to one embodiment of the present invention, temperature uniformity on the substrate surface can be improved. Brief explanation of the drawing

[0007] FIG. 1 is a schematic cross-sectional view illustrating a substrate fixing device. FIG. 2 is a schematic cross-sectional view illustrating the first layer of the heating element. FIG. 3 is a schematic cross-sectional view illustrating each layer of the heating element. Figure 4 is a graph illustrating the relationship between alumina content and electrical resistivity. FIG. 5 is a schematic cross-sectional view illustrating a method for manufacturing an electrostatic chuck. Figure 6 is a schematic cross-sectional view illustrating a method for manufacturing an electrostatic chuck. FIG. 7 is a schematic cross-sectional view illustrating a method for manufacturing an electrostatic chuck. FIG. 8 is a schematic cross-sectional view illustrating a method for manufacturing an electrostatic chuck. FIG. 9 is a schematic cross-sectional view illustrating a method for manufacturing an electrostatic chuck. Specific details for implementing the invention

[0008] Hereinafter, an embodiment will be described with reference to the attached drawings.

[0009] In the attached drawings, for convenience, parts functioning as features may be illustrated in an enlarged manner to facilitate understanding of the features, and it should be noted that the dimensional ratios of each component may differ in each drawing. Additionally, in the cross-sectional views, to facilitate understanding of the cross-sectional structure of each member, in some cases, the hatching of some members is replaced with a satin-finish pattern, and in some cases, the hatching of some members is omitted. Unless otherwise specified, "planar view" refers to viewing an object from a vertical direction (up-down direction in the drawings) in FIG. 1, etc. Also, unless otherwise specified, "planar shape" refers to the shape of an object viewed from a vertical direction in FIG. 1, etc. Additionally, in this specification, "up-down direction" and "left-right direction" are directions in which the direction in which the reference number representing each member in each drawing can be correctly read is set as the normal position. Additionally, unless otherwise specified, in the description of the present disclosure, the numerical range of “X1 to X2” defined by the lower limit (X1) and the upper limit (X2) refers to a range greater than or equal to X1 and less than or equal to X2.

[0010] (Overall configuration of the substrate fixing device (10))

[0011] As illustrated in FIG. 1, the substrate fixing device (10) comprises a base plate (20) and an electrostatic chuck (30) arranged on the base plate (20). The electrostatic chuck (30) is bonded to the upper surface of the base plate (20) by an adhesive (not shown), such as silicone resin, for example. Note that the electrostatic chuck (30) may also be fixed to the base plate (20) by screws. The base plate (20) is a member for mounting the electrostatic chuck (30). The electrostatic chuck (30) is a retaining body that holds the substrate (W1) which is the object to be adsorbed. The electrostatic chuck (30) is a temperature control device that controls the temperature of the substrate (W1), for example. Note that as the substrate (W1), a silicon wafer, for example, may be exemplified. The diameter of the substrate (W1) may be, for example, 8 inches, 12 inches, or 18 inches.

[0012] (Composition of base plate (20))

[0013] The base plate (20) has rigidity to support the electrostatic chuck (30). As a material for the base plate (20), metal materials such as aluminum and cemented carbide, and composite materials of such metal materials and ceramic materials may be used. In this embodiment, aluminum or an aluminum alloy with anodized surface is used, taking into account ease of availability, ease of processing, and good thermal conductivity.

[0014] The shape and size of the base plate (20) may be formed in any shape and any size. The base plate (20) is formed in a disc shape corresponding to, for example, the shape of the substrate (W1) placed on the electrostatic chuck (30). The diameter of the base plate (20) may be, for example, about 150 mm to 500 mm. The thickness of the base plate (20) may be, for example, about 10 mm to 50 mm. Here, in this specification, "disc shape" refers to a planar shape having a circular shape and a predetermined thickness. It should be noted that in the "disc shape," the thickness relative to the diameter is not important. Additionally, in this specification, "disc shape" also includes a shape in which a concave or protruding portion is partially formed.

[0015] A base plate (20) is provided with, for example, a cooling channel (21). The cooling channel (21) has an inlet section (22) provided at one end and an outlet section (23) provided at the other end. The cooling channel (21) is connected to, for example, a refrigerant control device (not shown) installed outside the substrate fixing device (10). The refrigerant control device introduces refrigerant into the cooling channel (21) from the inlet section (22) and discharges refrigerant from the outlet section (23). Since the refrigerant is circulated through the cooling channel (21) to cool the base plate (20), the substrate (W1) adsorbed on the electrostatic chuck (30) can be cooled. For example, water or galden may be used as the refrigerant. In addition to the cooling channel (21), a gas channel for introducing an inert gas to cool the substrate (W) adsorbed on the electrostatic chuck (30) may be provided on the base plate (20).

[0016] (Composition of the electrostatic chuck (30))

[0017] The electrostatic chuck (30) is formed, for example, in the shape of a disc. The diameter of the electrostatic chuck (30) may, for example, be equal to the diameter of the base plate (20) or be smaller than the diameter of the base plate (20). In this embodiment, the diameter of the electrostatic chuck (30) is equal to the diameter of the base plate (20). The diameter of the electrostatic chuck (30) may, for example, be about 150 mm to 300 mm. The thickness of the electrostatic chuck (30) may, for example, be about 1 mm to 10 mm.

[0018] The electrostatic chuck (30) includes an adsorption part (40) and a heating part (50). The electrostatic chuck (30) is, for example, a Johnson-Rahbek type electrostatic chuck. Note that the electrostatic chuck (30) may also be a Coulomb type electrostatic chuck.

[0019] (Composition of the adsorption part (40))

[0020] The adsorption portion (40) is laminated on the upper surface of the heating portion (50). The adsorption portion (40) includes an insulating substrate (41) and an electrostatic electrode (42).

[0021] The insulating substrate (41) has a substrate placement surface (41A) (here, the upper surface) on which the substrate (W1), which is the object to be adsorbed, is placed. The lower surface of the insulating substrate (41) is provided on the opposite side of the substrate placement surface (41A) in the thickness direction (up and down direction in the drawing) of the insulating substrate (41).

[0022] The insulating substrate (41) is, for example, a dielectric. As a material for the insulating substrate (41), a material having insulating properties may be used. As a material for the insulating substrate (41), ceramic materials such as aluminum oxide (Al2O3), aluminum nitride (AlN), and silicon nitride, and organic materials such as silicone resin and polyimide resin may be used. In this embodiment, ceramic materials such as aluminum oxide and aluminum nitride are adopted as materials for the insulating substrate (41) considering ease of availability, ease of processing, and relatively high resistance. The insulating substrate (41) is a sintered body formed by sintering a green sheet composed of, for example, a mixture of aluminum oxide and an organic material.

[0023] In FIG. 1, the insulating substrate (41) is illustrated as a single layer, but it should be noted that the insulating substrate (41) may have a structure in which a plurality of insulating layers are stacked.

[0024] The electrostatic electrode (42) is an electrode for adsorbing the substrate (W1). The electrostatic electrode (42) is embedded in the insulating substrate (41). The electrostatic electrode (42) is embedded, for example, in a portion located near the substrate mounting surface (41A) in the thickness direction of the electrostatic chuck (30). The electrostatic electrode (42) is electrically connected to an adsorption power source installed outside the substrate fixing device (10). When a predetermined voltage is applied from the adsorption power source, the electrostatic electrode (42) generates an adsorption force due to electrostatic charge between itself and the substrate (W1) mounted on the substrate mounting surface (41A). This enables the substrate (W1) to be adsorbed and maintained on the substrate mounting surface (41A). The higher the voltage applied to the electrostatic electrode (42), the stronger the adsorption holding force on the electrostatic chuck (30). The electrostatic electrode (42) may be unipolar or bipolar. For example, tungsten (W) or molybdenum (Mo) can be used as a material for the electrostatic electrode (42).

[0025] (Composition of the heating element (50))

[0026] The heating element (50) is installed, for example, between the base plate (20) and the adsorption element (40). The heating element (50) is stacked on the upper surface of the base plate (20). Additionally, the heating element (50) is stacked on the lower surface of the adsorption element (40). The heating element (50) is formed integrally with, for example, the adsorption element (40).

[0027] The heating element (50) includes, for example, a first layer (60) stacked on the adsorption element (40), a second layer (70) stacked on the first layer (60), and a third layer (80) stacked on the second layer (70).

[0028] The first layer (60) is laminated on the lower surface of the adsorption part (40), specifically on the lower surface of the insulating substrate (41). The first layer (60) includes a first heating element (61) and an insulating layer (62) covering the first heating element (61). The second layer (70) is laminated on the lower surface of the insulating layer (62). The second layer (70) includes a second heating element (71), a connection pattern (72), an insulating layer (73), and a via conductor (74). The third layer (80) is laminated on the lower surface of the insulating layer (73). The third layer (80) includes an insulating layer (81) and a power supply part (82).

[0029] In the heating section (50), the substrate body is formed by insulating layers (62, 73, 81). In the heating section (50), the first heating element (61), the second heating element (71), and the connection pattern (72) are embedded in the substrate body formed by insulating layers (62, 73, 81).

[0030] Here, an electrically insulating material may be used as the material for the insulating layer (62, 73, 81). For example, a material similar to the material of the insulating substrate (41) may be used as the material for the insulating layer (62, 73, 81). As the material for the insulating layer (62, 73, 81), ceramic materials such as aluminum oxide, aluminum nitride, and silicon nitride, and organic materials such as silicone resin and polyimide resin may be used. The insulating layer (62, 73, 81) of the present embodiment is a sintered body formed by sintering a green sheet composed of a mixture of aluminum oxide and organic materials. In each drawing, the interface between the insulating substrate (41) and the insulating layer (62), the interface between the insulating layer (62) and the insulating layer (73), and the interface between the insulating layer (73) and the insulating layer (81) are indicated by solid lines. Since these interfaces are formed by stacking multiple green sheets, depending on the stacking state, the position of the interface may differ, the interface may not be straight in cross-section, or the interface may be indistinct.

[0031] (Composition of the first layer (60))

[0032] The first heating element (61) is intended to heat the substrate (W1). The first heating element (61) is installed, for example, between the electrostatic electrode (42) and the lower surface of the electrostatic chuck (30) in the thickness direction of the electrostatic chuck (30). The first heating element (61) is installed, for example, in a plane parallel to the substrate mounting surface (41A). The first heating element (61) of this embodiment is laminated on the upper surface of the insulating layer (73). The first heating element (61) is electrically insulated from the electrostatic electrode (42). As a material for the first heating element (61), for example, copper (Cu), tungsten, nickel (Ni), and constantan (an alloy of Cu / Ni / Mn / Fe) may be used. The electrical resistivity of the first heating element (61) may be, for example, about 10 μΩ·cm to 150 μΩ·cm. The thickness of the first heating element (61) can be, for example, about 10 μm to 100 μm.

[0033] As illustrated in FIG. 2, the first heating element (61) is a multi-zone heater. The first heating element (61) includes a plurality of heating elements (61A, 61B, 61C) arranged independently for each of the plurality of regions (zones). Here, in the electrostatic chuck (30) of the present embodiment, three zones (Z1, Z2, Z3) are set in a concentric circular shape. Zone (Z1) is set on the outermost side. Zone (Z2) is set on the inner side relative to Zone (Z1). Zone (Z3) is set on the inner side relative to Zone (Z2).

[0034] Three heating elements (61A, 61B, 61C) are each installed in three zones (Z1, Z2, Z3). The three heating elements (61A, 61B, 61C) are formed in a concentric circular shape, for example, centered on the planar center of the electrostatic chuck (30). The three heating elements (61A, 61B, 61C) are installed on the same plane. The planar shape of the heating element (61A) arranged in zone (Z1) is formed, for example, as an annular shape surrounding the heating element (61B). The planar shape of the heating element (61B) arranged in zone (Z2) is formed, for example, as an annular shape surrounding the heating element (61C). The heating element (61C) arranged in zone (Z3) is formed, for example, as a circular shape.

[0035] In the first heating element (61), the temperature is individually controlled for each of the zones (Z1, Z2, Z3) to make the temperature of the entire substrate (W1) illustrated in FIG. 1 uniform. Specifically, in the first heating element (61), the amount of heat generated by the three heating elements (61A, 61B, 61C) is individually controlled. Here, although detailed illustration is omitted, each of the three heating elements (61A, 61B, 61C) has a single-stroke pattern. Additionally, the heating element (61A) has a pair of power supply patterns (P1) for electrically connecting to a heating power source installed outside the substrate fixing device (10). The pair of power supply patterns (P1) are installed at both ends of the single-stroke pattern. Although not illustrated, the heating elements (61B, 61C) also similarly have a pair of power supply patterns (P1). By independently applying voltage to each pair of power supply patterns (P1) of the heating elements (61A, 61B, 61C), each zone (Z1, Z2, Z3) can be individually temperature controlled.

[0036] As illustrated in FIG. 1, the insulating layer (62) is laminated on the lower surface of the insulating substrate (41). Additionally, the insulating layer (62) is laminated on the upper surface of the insulating layer (73) to cover the first heating element (61). The insulating layer (62) is formed to cover the side and upper surfaces of the first heating element (61). In FIG. 1, the insulating layer (62) is illustrated as a single layer, but it should be noted that the insulating layer (62) may have a structure in which a plurality of insulating layers are laminated.

[0037] (Composition of the second layer (70))

[0038] An insulating layer (73) is laminated on the lower surface of the insulating layer (62). The insulating layer (73) is formed to cover, for example, the side and upper surface of the second heating element (71) and the side and upper surface of the connection pattern (72). The insulating layer (73) is formed to cover, for example, the lower surface of the first heating element (61). In FIG. 1, the insulating layer (73) is illustrated as a single layer, but it should be noted that the insulating layer (73) may have a structure in which a plurality of insulating layers are laminated.

[0039] A via conductor (74) is formed by penetrating the insulating layer (73) in the thickness direction. The via conductor (74) is formed to fill, for example, a through hole (73X) penetrating the insulating layer (73) in the thickness direction. The via conductor (74) is installed between the power supply pattern (P1) and the connection pattern (72) of the first heating element (61). The via conductor (74) electrically connects the first heating element (61) and the connection pattern (72).

[0040] As illustrated in FIG. 3, a pair of via conductors (74) are formed in the second layer (70), each connected to a pair of feed patterns (P1). Each via conductor (74) is provided to overlap with each feed pattern (P1) in a planar view.

[0041] As illustrated in FIG. 1, the second heating element (71) is installed, for example, between the first heating element (61) and the lower surface of the electrostatic chuck (30) in the thickness direction of the electrostatic chuck (30). The second heating element (71) is installed, for example, in a plane parallel to the substrate mounting surface (41A). The second heating element (71) of the present embodiment is laminated on the upper surface of the insulating layer (81). The second heating element (71) is intended to heat the substrate (W1). The second heating element (71) is electrically insulated from the electrostatic electrode (42). The second heating element (71) is electrically insulated from the first heating element (61). For example, copper, tungsten, nickel, and constantan may be used as materials for the second heating element (71). The electrical resistivity of the second heating element (71) may be, for example, about 10 μΩ·cm to 150 μΩ·cm. The thickness of the second heating element (71) can be, for example, about 10 μm to 100 μm.

[0042] The second heating element (71) is electrically connected to a heating power source installed outside the substrate fixing device (10). The second heating element (71) generates heat in response to the voltage applied from the heating power source. The second heating element (71) heats the substrate mounting surface (41A) to a predetermined temperature. Note that voltage from the heating power source is independently applied to the first heating element (61) and the second heating element (71). Accordingly, the amount of heat generated by the first heating element (61) and the second heating element (71) is controlled individually.

[0043] As illustrated in FIG. 3, the planar shape of the second heating element (71) is formed, for example, in an annular (ring shape). The second heating element (71) is installed, for example, within a zone (Z1) (see FIG. 2). The second heating element (71) is formed to overlap, for example, a part of the heating element (61A) of the first heating element (61) in a planar state.

[0044] As illustrated in FIG. 1, the connection pattern (72) is installed on the same plane as the second heating element (71). The connection pattern (72) of this embodiment is laminated on the upper surface of the insulating layer (81). The connection pattern (72) is a pattern for electrically connecting the first heating element (61) and the power supply unit (82). The connection pattern (72) extends along a planar direction (left-right direction in the drawing) perpendicular to the thickness direction of, for example, the electrostatic chuck (30). The upper surface of the first stage of the connection pattern (72) is connected to the power supply pattern (P1) of the first heating element (61) through a via conductor (74). The lower surface of the second stage of the connection pattern (72) is connected to the power supply unit (82) that penetrates the insulating layer (81) in the thickness direction.

[0045] Note that in each drawing, for the sake of simplification, only the via conductor (74), connection pattern (72), and power supply portion (82) connected to the heating element (61A) among the heating elements (61A, 61B, 61C) are illustrated. However, although the illustration is omitted, similar via conductors (74), connection patterns (72), and power supply portions (82) are also installed in the heating elements (61B, 61C).

[0046] As illustrated in FIG. 3, a pair of connection patterns (72) are formed in the second layer (70), each connected to a pair of via conductors (74). The pair of connection patterns (72) are installed spaced apart from each other. The pair of connection patterns (72) are installed on the inside of the second heating element (71) that forms an annular shape, for example, in a planar view. Each connection pattern (72) is formed to overlap with the power supply pattern (P1) of the heating element (61A) and each via conductor (74) in a planar view, and is also formed to overlap with the power supply portion (82) in a planar view. Here, the power supply portion (82) is formed so as not to overlap with the via conductors (74) in a planar view. Each connection pattern (72) is formed to extend in a planar direction between the via conductors (74) and the power supply portion (82). The planar shape of each connection pattern (72) is formed, for example, in an oblong shape.

[0047] Here, the connection pattern (72) for connecting the first heating element (61) and the power supply unit (82) does not function as a heating element for heating the substrate (W1) illustrated in FIG. 1. The electrical resistivity of the connection pattern (72) is set lower than the electrical resistivity of the second heating element (71). That is, the connection pattern (72) is formed of a material having a lower electrical resistivity than the material forming the second heating element (71). The electrical resistivity of the connection pattern (72) may be, for example, about 0.1 μΩ·cm to 10 μΩ·cm. The alumina content in the connection pattern (72) is, for example, lower than the alumina content in the second heating element (71). That is, the alumina content in the material forming the connection pattern (72) is lower than the alumina content in the material forming the second heating element (71). The material forming the connection pattern (72) of this embodiment does not contain alumina.

[0048] FIG. 4 is a graph illustrating the relationship between the alumina content and the electrical resistivity. FIG. 4 illustrates the change in electrical resistivity when the alumina content in the tungsten paste changes. As can be clearly seen from FIG. 4, as the alumina content increases, the electrical resistivity increases. Therefore, in this embodiment, by changing the alumina content, the electrical resistivity of the connection pattern (72) is set lower than the electrical resistivity of the second heating element (71). Specifically, the connection pattern (72) of this embodiment is formed by a tungsten paste that does not contain alumina. In this case, the electrical resistivity of the connection pattern (72) is approximately 10 μΩ·cm. Additionally, the second heating element (71) of this embodiment is formed by a tungsten paste containing 26 wt% alumina. In this case, the electrical resistivity of the second heating element (71) is approximately 120 μΩ·cm.

[0049] (Composition of the third layer (80))

[0050] An insulating layer (81) is laminated on the lower surface of the insulating layer (73). The insulating layer (81) is formed to cover the lower surface of the second heating element (71) and the lower surface of the connection pattern (72). The lower surface of the insulating layer (81) is bonded to the upper surface of the base plate (20), for example, by an adhesive (not shown). In FIG. 1, the insulating layer (81) is illustrated as a single layer, but it should be noted that the insulating layer (81) may have a structure in which a plurality of insulating layers are laminated.

[0051] The power supply unit (82) is electrically connected to the connection pattern (72). The power supply unit (82) is formed to fill, for example, a through hole (81X) that penetrates the insulating layer (81) in the thickness direction. The power supply unit (82) is electrically connected to a heating power source, for example, through a power supply line (83). When voltage is applied from the heating power source to the power supply unit (82) through the power supply line (83), voltage is applied to the first heating element (61) through the power supply unit (82), the connection pattern (72), and the via conductor (74). After that, the first heating element (61) generates heat in response to the voltage applied from the heating power source.

[0052] (Method for manufacturing an electrostatic chuck (30))

[0053] Next, a method for manufacturing the electrostatic chuck (30) will be described. Here, a method for manufacturing the heating element (50) of the electrostatic chuck (30) will be described.

[0054] First, in the step illustrated in FIG. 5, green sheets (91, 92, 93) composed of ceramic materials and organic materials are prepared. Each of the green sheets (91, 92, 93) is a sheet-shaped material obtained, for example, by mixing alumina with a binder, solvent, etc. The size of the planar shape of each green sheet (91, 92, 93) corresponds to the size of the planar shape of the heating element (50) illustrated in FIG. 1.

[0055] The green sheet (91) becomes the insulating layer (62) illustrated in FIG. 1 by being fired in the step described below. The green sheet (92) becomes the insulating layer (73) illustrated in FIG. 1 by being fired in the step described below. The green sheet (92) is provided with a through hole (73X) that penetrates the green sheet (92) in the thickness direction. The green sheet (93) becomes the insulating layer (81) illustrated in FIG. 1 by being fired in the step described below. The green sheet (93) is provided with a through hole (81X) that penetrates the green sheet (93) in the thickness direction. Note that the through holes (73X, 81X) may be formed, for example, by laser processing or mechanical processing.

[0056] Next, in the step illustrated in FIG. 6, a via conductor (74) filling the through hole (73X) is formed by filling the through hole (73X) with a conductive paste (e.g., tungsten paste). Additionally, a feed portion (82) filling the through hole (81X) is formed by filling the through hole (81X) with a conductive paste (e.g., tungsten paste). The via conductor (74) and the feed portion (82) may be formed, for example, by screen printing.

[0057] Next, in the step illustrated in FIG. 7, a first heating element (61) is formed by applying a conductive paste (e.g., tungsten paste) to the lower surface of a green sheet (91) by, for example, a screen printing method and drying it. At this time, the first heating element (61) is formed to have three heating elements (61A, 61B, 61C) formed in a concentric circular shape. Additionally, the first heating element (61) is formed to have a power supply pattern (P1) installed to overlap with a via conductor (74) in a planar view. Note that the first heating element (61) may be formed on the upper surface of the green sheet (92).

[0058] Additionally, in the step illustrated in FIG. 7, a second heating element (71) is formed by applying a first conductive paste to the lower surface of a green sheet (92), for example, by screen printing and drying. As the first conductive paste, a conductive paste having a composition with high electrical resistivity may be used. For example, as the first conductive paste, a tungsten paste containing a predetermined amount of alumina (here, 26 wt%) may be used. In this step, only the second heating element (71) is formed among the second heating element (71) and the connection pattern (72) illustrated in FIG. 1. Note that the second heating element (71) may be formed on the upper surface of the green sheet (93).

[0059] Next, in the step illustrated in FIG. 8, a connection pattern (72) is formed by applying a second conductive paste to the lower surface of the green sheet (92), for example, by screen printing, and drying it. As the second conductive paste, for example, a conductive paste having a composition with a lower electrical resistivity than the first conductive paste may be used. For example, as the second conductive paste, a tungsten paste that does not contain alumina may be used. The connection pattern (72) is formed to overlap with the via conductor (74) in a planar view, and is also formed to overlap with the feed portion (82) in a planar view. Note that the connection pattern (72) may be formed on the upper surface of the green sheet (93).

[0060] As described above, first, a second heating element (71) is formed on the lower surface of a green sheet (92) using a first conductive paste. Then, a connection pattern (72) is formed on the lower surface of the green sheet (92) using a second conductive paste having a composition with a lower electrical resistivity than the first conductive paste. In this way, the second heating element (71) and the connection pattern (72) having different electrical resistivity can be formed on the same plane.

[0061] Next, in the step illustrated in FIG. 9, a green sheet (92) and a green sheet (91) are sequentially laminated on a green sheet (93). The green sheets (91, 92, 93) are joined together, for example, by applying pressure while heating the green sheet.

[0062] Next, a structure in which green sheets (91, 92, 93) are laminated is fired. As a result, the green sheets (91, 92, 93) are sintered, thereby obtaining an insulating layer (62, 73, 81) for each. Then, a heating part (50) can be manufactured in which a first layer (60) including a first heating element (61) and an insulating layer (62), a second layer (70) including a second heating element (71), a connection pattern (72), an insulating layer (73), and a via conductor (74), and a third layer (80) including an insulating layer (81) and a power supply part (82) are sequentially laminated. Although omitted from description in this specification, it should be noted that the adsorption part (40) illustrated in FIG. 1 can also be formed together with the heating part (50).

[0063] Note that in this embodiment, the green sheet (91) is an example of a first green sheet and the green sheet (92) is an example of a second green sheet.

[0064] (Effect of the operation of the present embodiment)

[0065] Next, the effects of the present embodiment will be explained.

[0066] (1) The second heating element (71) and the connection pattern (72) are installed on the same plane. Here, the connection pattern (72) is intended to connect the first heating element (61) and the power supply unit (82), and does not function as a heating element for heating the substrate (W1). When the electrical resistivity of the connection pattern (72) is set to be the same as the electrical resistivity of the second heating element (71) that functions as a heating element, the connection pattern (72) heats up to the same degree as the second heating element (71). The heat generated by the connection pattern (72) may cause temperature non-uniformity on the substrate mounting surface (41A).

[0067] In contrast, in the electrostatic chuck (30) of the present embodiment, the electrical resistivity of the connection pattern (72) is set lower than the electrical resistivity of the second heating element (71). Therefore, when voltage is applied to the connection pattern (72), the heat generation of the connection pattern (72) can be appropriately suppressed. Consequently, unintended temperature rise in some areas of the substrate mounting surface (41A) caused by the heat generation of the connection pattern (72) can be suppressed, and temperature non-uniformity on the substrate mounting surface (41A) can be appropriately suppressed. As a result, temperature uniformity on the substrate mounting surface (41A) can be improved.

[0068] (2) The alumina content in the material forming the connection pattern (72) is set lower than the alumina content in the material forming the second heating element (71). According to this configuration, by adjusting the alumina content, the electrical resistivity of the connection pattern (72) can be easily adjusted to be lower than the electrical resistivity of the second heating element (71).

[0069] (3) The material forming the connection pattern (72) of this embodiment does not contain alumina. According to this configuration, the electrical resistivity of the connection pattern (72) can be set lower. Therefore, when voltage is applied to the connection pattern (72), the heat generation of the connection pattern (72) can be more appropriately suppressed.

[0070] (Variation embodiment)

[0071] The above embodiments may be implemented with modifications as follows. The above embodiments and the following modified embodiments may be implemented in combination with one another within a technically consistent scope.

[0072] The structure of the connection pattern (72) in the above embodiment can be appropriately modified. For example, the planar shape of the connection pattern (72) can be formed in any shape and any size. For example, the planar shape of the connection pattern (72) can be formed in a rectangular shape or an L-shape.

[0073] The structure of the second heating element (71) in the above embodiment can be appropriately modified. For example, the planar shape of the second heating element (71) can be formed in any shape and any size. For example, the planar shape of the second heating element (71) can be formed in a rectangular frame shape.

[0074] In the above embodiment, the second heating element (71) is formed to partially overlap with the heating element (61A) in a planar view, but the location where the second heating element (71) is formed is not limited thereto. For example, the second heating element (71) may be formed to partially overlap with the heating element (61C) in a planar view.

[0075] In the above embodiment, the connection pattern (72) is installed on the inside of the second heating element (71) having an annular shape. However, this limitation is not intended. For example, the connection pattern (72) may be installed on the outside of the second heating element (71).

[0076] The structure of the first heating element (61) in the above embodiment can be appropriately modified.

[0077] In the above embodiment, three heating elements (61A, 61B, 61C) are formed in a concentric circle shape. However, for example, the three heating elements (61A, 61B, 61C) may be formed in a rectangular shape on a concentric circle.

[0078] In the above embodiment, the first heating element (61) has a structure comprising three heating elements (61A, 61B, 61C). However, the number of heating elements included in the first heating element (61) is not particularly limited. For example, the number of heating elements included in the first heating element (61) may be 2 or 4 or more.

[0079] In the above embodiment, the number of insulating layers (62, 73, 81) within the heating element (50) is not particularly limited.

[0080] In the above embodiment, the number and shape of the zones (Z1, Z2, Z3) within the electrostatic chuck (30) are not particularly limited. For example, the zones (Z1, Z2, Z3) within the electrostatic chuck (30) may be set on concentric circles in a rectangular shape. For example, the number of zones within the electrostatic chuck (30) may be 2 or 4 or more.

[0081] In the above embodiment, after the second heating element (72) is formed on the lower surface of the green sheet (92), the connection pattern (72) is formed. However, this limitation is not intended. For example, after the connection pattern (72) is formed on the lower surface of the green sheet (92), the second heating element (71) may be formed.

[0082] In the above embodiment, a first heating element (61) is formed on the lower surface of the green sheet (91), and a second heating element (71) and a connection pattern (72) are formed on the lower surface of the green sheet (92). However, such limitation is not intended. For example, the first heating element (61) may be formed on the upper surface of the green sheet (92), and the second heating element (71) and the connection pattern (72) may be formed on the lower surface of the green sheet (92).

[0083] An embossing structure may be provided on the substrate mounting surface (41A) of the electrostatic chuck (30) of the above embodiment.

[0084] The structure of the base plate (20) of the above embodiment is not particularly limited. For example, the shape of the cooling channel (21) is not particularly limited.

[0085] The substrate fixing device (10) of the above embodiment is applied to a semiconductor manufacturing device such as a dry etching device. Examples of dry etching devices include a parallel planar reactive ion etching device. The substrate fixing device (10) may also be applied to semiconductor manufacturing devices such as a plasma CVD (Chemical Vapor Deposition) device and a sputtering device.

Claims

Claim 1 An electrostatic chuck comprising: an adsorption portion configured to adsorb and maintain an object to be adsorbed; and a heating portion stacked on the adsorption portion, wherein the heating portion comprises a first layer including a first heating element, a second layer stacked on the first layer including a second heating element and a connection pattern electrically connected to the first heating element, and a third layer stacked on the second layer including a power supply portion electrically connected to the connection pattern, wherein the first heating element includes a plurality of heating elements independently arranged for each of a plurality of zones, and the second heating element and the connection pattern are installed on the same plane, and the electrical resistivity of the connection pattern is lower than the electrical resistivity of the second heating element. Claim 2 An electrostatic chuck according to claim 1, wherein the alumina content in the material forming the connection pattern is lower than the alumina content in the material forming the second heating element. Claim 3 In paragraph 2, the material forming the connection pattern is an electrostatic chuck that does not contain alumina. Claim 4 An electrostatic chuck according to claim 1, wherein the planar shape of the second heating element is formed as an annular shape, and the connection pattern is installed on the inner side relative to the second heating element in a planar state. Claim 5 An electrostatic chuck according to claim 1, wherein the plurality of heating elements are formed in a concentric circular shape on the same plane, and the connection pattern is electrically connected to the first heating element through a via conductor installed between the first heating element and the connection pattern. Claim 6 A substrate fixing device comprising: an electrostatic chuck according to any one of claims 1 to 5; and a base plate bonded to the electrostatic chuck. Claim 7 A method for manufacturing an electrostatic chuck comprising an adsorption portion configured to adsorb and maintain an object to be adsorbed, and a heating portion stacked on the adsorption portion, the method comprising: preparing a first green sheet and a second green sheet; forming a first heating element on the lower surface of the first green sheet; forming a through hole penetrating the second green sheet in the thickness direction; forming a via conductor filling the through hole so as to overlap with the first heating element in a planar view; forming a second heating element on the lower surface of the second green sheet so as not to overlap with the via conductor in a planar view; forming a connection pattern on the lower surface of the second green sheet having an electrical resistivity lower than the electrical resistivity of the second heating element so as to be connected to the via conductor; stacking the first green sheet on the upper surface of the second green sheet; and firing the first green sheet and the second green sheet stacked together.

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