Electrostatic chuck heater

Abstract

An electrostatic chuck heater includes: an electrostatic chuck in which an electrostatic electrode is embedded in a ceramic sintered body; a cooling member that cools the electrostatic chuck; and a heater layer disposed between the electrostatic chuck and the cooling member, in which a plurality of metal layers including a resistance heating element layer are buried in multiple stages. The heater layer has a ceramic insulating layer with a thickness of 2 μm or more and 50 μm or less between the metal layers.

Description

Technical Field

[0001] The present invention relates to an electrostatic chuck heater. Background Art

[0002] Conventionally, in film formation processes such as transportation, exposure, and CVD of semiconductor wafers, and in microfabrication processes such as cleaning, etching, and cutting, an electrostatic chuck heater for adsorbing and holding a wafer is used. As such an electrostatic chuck heater, an electrostatic chuck heater 110 as shown in Figure 3 is known. The electrostatic chuck heater 110 bonds an electrostatic chuck 120 in which an electrostatic electrode 124 and a plurality of metal layers 126 (including a resistive heating element layer) are embedded in a ceramic sintered body 122 and a cooling member 130 for cooling the electrostatic chuck 120 using an adhesive layer 150. In this case, since a green sheet is used before firing, considering dimensional changes, it is necessary to increase the thickness of one green sheet to a certain extent, and there is a problem that the overall thickness of the ceramic sintered body 122 becomes thick. On the other hand, in Patent Document 1, an electrostatic chuck heater 210 as shown in Figure 4 is also known. The electrostatic chuck heater 210 includes: an electrostatic chuck 220 in which an electrostatic electrode 224 is embedded in a ceramic sintered body 222; a cooling member 230 for cooling the electrostatic chuck 220; and a sheet heater 240 provided between the electrostatic chuck 220 and the cooling member 230. The sheet heater 240 has a plurality of metal layers 242 including a resistive heating element layer embedded in a resin sheet 241 in multiple stages. The sheet heater 240 is bonded to the electrostatic chuck 220 and the cooling member 230 via adhesive layers 250, respectively. Figure 4 The combined thickness of the electrostatic chuck 220 and the sheet heater 240 in the electrostatic chuck heater 210 can be thinner than the thickness of the Figure 3 ceramic sintered body 122.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Pamphlet of International Publication No. 2017 / 29876 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, since the thermal resistance of the sheet heater 240 provided between the electrostatic chuck 220 and the cooling member 230 is large, there is a problem that it is difficult to quickly cool the wafer electrostatically adsorbed on the electrostatic chuck 220 when there is an external heat input such as plasma heat input.

[0008] The present invention has been completed to solve such problems, and its main object is to improve the processing ability for external heat input.

[0009] Method for Solving the Problem

[0010] The electrostatic chuck heater of the present invention includes:

[0011] An electrostatic chuck in which an electrostatic electrode is embedded in a ceramic sintered body;

[0012] A cooling member that cools the electrostatic chuck; and

[0013] A heater layer that is provided between the electrostatic chuck and the cooling member and in which a plurality of metal layers including a resistance heating element layer are buried in multiple stages,

[0014] The heater layer has a ceramic insulating layer with a thickness of 2 μm or more and 50 μm or less between the metal layers.

[0015] In this electrostatic chuck heater, the heater layer has a ceramic insulating layer with a thickness of 2 μm or more and 50 μm or less between the metal layers. If the thickness of the ceramic insulating layer is within this numerical range, the insulation breakdown voltage generally required for the resistance heating element layer is satisfied. In addition, the overall thickness of the heater layer becomes thinner, and the heat capacity of the heater layer becomes smaller. Furthermore, ceramics have excellent thermal conductivity compared to resins. As a result, the thermal resistance of the heater layer provided between the electrostatic chuck and the cooling member becomes smaller, and rapid cooling can be performed in the case of external heat input such as plasma heat input to the wafer electrostatically adsorbed on the electrostatic chuck. Thus, according to the electrostatic chuck heater of the present invention, the processing ability for external heat input is improved.

[0016] In the electrostatic chuck heater of the present invention, it is preferable that the withstand voltage of each layer of the ceramic insulating layer is AC200V or more. In this way, it is possible to sufficiently prevent insulation breakdown when used as an electrostatic chuck heater.

[0017] In the electrostatic chuck heater of the present invention, it is preferable that the porosity of the ceramic insulating layer is 0.5% or less. In this way, the withstand voltage performance per unit thickness can be improved, the thickness of the heater layer required to ensure the withstand voltage can be made thinner, and the thermal resistance becomes smaller.

[0018] In the electrostatic chuck heater of the present invention, it is preferable that the heater layer has 3 or more layers of the ceramic insulating layer, and more preferably 5 or more layers. In this way, it is possible to easily design a multi-region heater (a heater in which the electrostatic chuck is divided into multiple regions and a resistance heating element is arranged in each region).

[0019] In the electrostatic chuck heater of the present invention, the ceramic insulating layer may also be an aerosol deposition (AD) film. AD is suitable for forming a thin film of fine ceramic particles with high precision. In addition, since AD can form a film of ceramic particles through the impact curing phenomenon, it is not necessary to sinter the ceramic particles at a high temperature.

[0020] In the electrostatic chuck heater of the present invention, the metal layer may also be an AD film, a CVD film, a PVD film, or a coated film. The metal layer can be formed by printing or the like, but is preferably formed by an AD method (including a plasma AD method), a CVD method, a PVD method, a plating method, or the like. They are suitable for forming a thin film of fine metal particles with high precision. In addition, these do not require the use of a paste obtained by mixing metal particles and a resin component.

[0021] In the electrostatic chuck heater of the present invention, the metal layer may include a jumper layer, and a jumper for supplying power to the resistance heating element layer is wired in the jumper layer. In particular, when one resistance heating element layer is divided into a plurality of regions and a resistance heating element is arranged in each region, it is preferable to provide a jumper layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a longitudinal sectional view of the electrostatic chuck heater of the present embodiment.

[0023] Figure 2 is a longitudinal sectional view of a sample fabricated in an experimental example.

[0024] Figure 3 is a longitudinal sectional view of a conventional electrostatic chuck heater.

[0025] Figure 4 is a longitudinal sectional view of a conventional electrostatic chuck heater. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Figure 1 is a longitudinal sectional view of the electrostatic chuck heater of the present embodiment.

[0027] As Figure 1 shown, the electrostatic chuck heater 10 includes an electrostatic chuck 20, a cooling member 30, and a heater layer 40. The electrostatic chuck 20 has an electrostatic electrode 24 embedded in a disk-shaped ceramic sintered body 22, and when a voltage is applied to the electrostatic electrode 24, a wafer (not shown) placed on the upper surface of the electrostatic chuck 20 is electrostatically adsorbed. The cooling member 30 is a metal member having a refrigerant passage (not shown) therein and is used to cool the electrostatic chuck 20. The heater layer 40 is provided between the electrostatic chuck 20 and the cooling member 30, and a plurality of metal layers 42 including resistance heating element layers 44a, 44b, jumper layers 46a, 46b are buried in multiple stages. The heater layer 40 is directly formed on the surface of the electrostatic chuck 20 opposite to the wafer adsorption surface and is bonded to the cooling member 30 via an adhesive layer 50.

[0028] The heater layer 40 has a ceramic insulating layer 48 with a thickness of 2 μm or more and 50 μm or less between the metal layers 42. The ceramic insulating layer 48 is preferably an AD film formed by the AD method using ceramic particles. Compared with a spray-coated film, the AD film can be made to have high insulation and be thin. The metal layer 42 is preferably an AD film formed by the AD method using metal particles, a layer formed by the CVD method, the PVD method, or the plating method. The metal layer 42 includes an upper resistance heating element layer 44a, an upper jumper layer 46a, a lower jumper layer 46b, and a lower resistance heating element layer 44b. The upper resistance heating element layer 44a is divided into a plurality of regions, and a resistance heating element is wired in each region. The resistance heating element is wired from one end to the other end in a single stroke manner throughout the region. The lower resistance heating element layer 44b is divided into regions with a smaller number than the upper resistance heating element layer, and a resistance heating element is wired in each region. The upper and lower jumper layers 46a and 46b each have a plurality of jumpers. The jumpers supply power to the resistance heating elements included in the upper and lower resistance heating element layers 44a and 44b from a heater power supply respectively.

[0029] In the electrostatic chuck heater 10 of the present embodiment described above, the heater layer 40 has a ceramic insulating layer 48 with a thickness of 2 μm or more and 50 μm or less between the metal layers 42. If the thickness of the ceramic insulating layer 48 is within this numerical range, the insulation breakdown voltage usually required for the resistance heating element layers 44a and 44b is satisfied. In addition, the overall thickness of the heater layer 40 becomes thinner, and the heat capacity of the heater layer 40 becomes smaller. Furthermore, ceramics have excellent thermal conductivity compared to resins. As a result, the thermal resistance of the heater layer 40 provided between the electrostatic chuck 20 and the cooling member 30 becomes smaller, and cooling can be performed rapidly in the case where there is an external heat input such as plasma heat input to the wafer electrostatically adsorbed on the electrostatic chuck 20. Thus, according to the electrostatic chuck heater 10 of the present embodiment, the processing ability for external heat input is improved.

[0030] In addition, the withstand voltage (insulation breakdown voltage) of each layer of the ceramic insulating layer 48 is preferably AC200V or more. In this way, it is possible to sufficiently prevent insulation breakdown when used as the electrostatic chuck heater 10.

[0031] Furthermore, the porosity of the ceramic insulating layer 48 is preferably 0.5% or less. In this way, the withstand voltage performance per unit thickness can be improved, the thickness of the heater layer required to ensure the withstand voltage can be made thinner, and the thermal resistance becomes smaller.

[0032] In addition, the heater layer 40 preferably has three or more ceramic insulating layers 48, and more preferably five or more. In this way, it is possible to easily design a multi-region heater.

[0033] Moreover, the ceramic insulating layer 48 is preferably an AD film. AD is suitable for forming a thin layer of fine ceramic particles with high precision. In addition, AD can form a film of ceramic particles through the impact curing phenomenon, so there is no need to sinter the ceramic particles at a high temperature.

[0034] Moreover, the metal layer 42 further includes jumper layers 46a and 46b, and jumpers for supplying power to the resistive heating element layers 44a and 44b are wired in the jumper layers 46a and 46b. In particular, when one resistive heating element layer is divided into multiple regions and a resistive heating element is arranged in each region, it is preferable to provide a jumper layer.

[0035] It should be noted that the present invention is not limited by any of the above embodiments, and can of course be implemented in various ways as long as it belongs to the technical scope of the present invention.

[0036] Examples

[0037] [Experimental Examples 1-6]

[0038] As Figure 2 shown, a sample S in which an electrostatic chuck 70 and a heater layer 80 are laminated was fabricated. The electrostatic chuck 70 has a structure in which an electrostatic electrode 74 is embedded in an alumina ceramic sintered body 72 with a diameter of . The layer on the upper side of the alumina ceramic sintered body 72 with the electrostatic electrode 74 as the boundary is referred to as a dielectric layer 72a, and the layer on the lower side is referred to as an insulating layer 72b. The thickness of the dielectric layer 72a is 0.4 [mm], and the thickness of the insulating layer 72b is 0.5 [mm]. The heater layer 80 has a structure with six metal layers 82 inside, an alumina ceramic interlayer insulating film 84 is provided between the metal layers 82, and an alumina ceramic back insulating film 86 is provided on the back surface of the lowermost metal layer 82.

[0039] In Experimental Examples 1-4, first, the electrostatic chuck 70 was fabricated. Then, after forming one metal layer 82 on the back surface of the electrostatic chuck 70, one insulating film (interlayer insulating film 84) was formed by the AD method so as to cover the metal layer 82. Then, by repeatedly performing the operation of forming one metal layer 82 on the back surface of the insulating film and then forming one insulating film by the AD method so as to cover the metal layer 82, the sample S was fabricated. The last insulating film becomes the back insulating film 86. In Experimental Example 5, except that the spraying method was used instead of the AD method, the sample S was fabricated in the same manner as in Experimental Examples 1-4. In Experimental Example 6, by prefabricating a plurality of tape-shaped bodies, after forming one metal layer on the back surface of the electrostatic chuck 70, one tape-shaped body was laminated, and then after forming a metal layer on the back surface of the tape-shaped body, the operation of laminating other tape-shaped bodies was repeatedly performed so as to cover the metal layer, and finally the whole was sintered to fabricate the sample S.

[0040] Regarding each experimental example, information regarding the thickness of the dielectric layer 72a, the thickness of the insulating layer 72b, the total number of metal layers 82, information related to the interlayer insulating film 84, the thickness of the back insulating film 86, and the sample S is summarized in Table 1. As information related to the interlayer insulating film 84, the material, number of layers, manufacturing method, thickness, breakdown voltage, and total thickness are shown. The breakdown voltage is measured by applying an AC potential difference across both sides of the interlayer insulating film 84. Additionally, as information related to the sample S, the total thickness, thermal resistance (heat dissipation performance), and the time required to raise the temperature by 50°C with 1 kW (theoretical value) are shown.

[0041] [Table 1]

[0042]

[0043] In Experimental Examples 1 and 2 where the thickness of the interlayer insulating film 84 (AD film) is 2 μm and 50 μm, the breakdown voltage required for each layer (AC 200 V or more) is satisfied. Additionally, the overall thickness of the heater layer 80 (the sum of the total thickness of the interlayer insulating film 84 and the back insulating film 86) is as thin as 0.3 mm or less, the heat capacity and thermal resistance of the heater layer 80 are small, and the time required to raise the temperature by 50°C with 1 kW is also short. On the other hand, in Experimental Example 3 where the thickness of the interlayer insulating film 84 (AD film) is 1.5 μm, the breakdown voltage is lower than the breakdown voltage required for each layer. Additionally, in Experimental Example 4 where the thickness of the interlayer insulating film 84 (AD film) is 60 μm, cracks are generated. It is considered that the cause of the cracks is the increase in the internal stress of the AD film. From the above, it can be seen that the thickness of the interlayer insulating film 84 is preferably 2 μm or more and 50 μm or less.

[0044] In Experimental Example 5 where the thickness of the interlayer insulating film 84 (spray-coated film) is 50 μm, the breakdown voltage required for each layer (AC 200 V or more) is satisfied. The overall thickness of the heater layer 80 is also relatively thin, being 0.5 mm or less, the heat capacity and thermal resistance of the heater layer 80 are small, and the time required to raise the temperature by 50°C with 1 kW is also short. However, this time is slightly longer than that of the AD film. It is considered that the reason for this is that the porosity of the spray-coated film is in the single-digit percentage points, which is higher than the porosity of the AD film (0.5% or less).

[0045] In Experimental Example 6 where a film obtained by tape forming and then firing is used as the interlayer insulating film 84, although the withstand voltage (AC 200 V or more) required for each layer is satisfied, the overall thickness of the heater layer 80 is thick, being 1.25 mm. The heat capacity and thermal resistance of the heater layer 80 become large, and the time required to raise the temperature by 50 °C with 1 kW becomes long. Although not shown in Table 1, in the case of using powder forming instead of tape forming, the overall thickness of the heater layer 80 becomes even thicker, being 3 mm, and the time required to raise the temperature by 50 °C with 1 kW exceeds 40 seconds. It should be noted that when using the manufacturing methods of tape forming and powder forming, due to firing strain, a deviation occurs in the buried position inside the ceramic. Therefore, compared with the case of manufacturing the interlayer insulating film 84 using the AD method or the sputtering method, it needs to be made thicker further. As a result, the heat capacity and thermal resistance become large.

[0046] It should be noted that Experimental Examples 1, 2, and 5 correspond to the embodiments of the present invention, and Experimental Examples 3, 4, and 6 correspond to the comparative examples. Of course, these embodiments do not limit the present invention in any way.

[0047] This application claims the priority of Japanese Patent Application No. 2019-121489 filed on June 28, 2019, and incorporates its entire content herein by reference.

[0048] Industrial Applicability

[0049] The electrostatic chuck heater of the present invention can be used, for example, in film formation processes such as transportation, exposure, and CVD of semiconductor wafers, and in microfabrication processes such as cleaning, etching, and cutting.

[0050] Symbol Explanation

[0051] 10 Electrostatic chuck heater, 20 Electrostatic chuck, 22 Ceramic sintered body, 24 Electrostatic electrode, 30 Cooling component, 40 Heater layer, 42 Metal layer, 44a, 44b Resistance heating element layer, 46a, 46b Jumper layer, 48 Ceramic insulating layer, 50 Adhesive layer, 70 Electrostatic chuck, 72 Alumina ceramic sintered body, 72a Dielectric layer, 72b Insulating layer, 74 Electrostatic electrode, 80 Heater layer, 82 Metal layer, 84 Interlayer insulating film, 86 Back insulating film, 110 Electrostatic chuck heater, 120 Electrostatic chuck, 122 Ceramic sintered body, 124 Electrostatic electrode, 126 Metal layer, 130 Cooling component, 150 Adhesive layer, 210 Electrostatic chuck heater, 220 Electrostatic chuck, 222 Ceramic sintered body, 224 Electrostatic electrode, 230 Cooling component, 240 Chip heater, 241 Resin sheet, 242 Metal layer, 250 Adhesive layer, S Sample.

Claims

1. An electrostatic chuck heater, comprising: An electrostatic chuck in which an electrostatic electrode is embedded in a ceramic sintered body; A cooling member that cools the electrostatic chuck; and A heater layer provided between the electrostatic chuck and the cooling member, in which a plurality of metal layers composed of a plurality of resistor heating element layers in which resistor heating elements are wired and a plurality of jumper layers having jumpers for supplying power to the resistor heating elements are buried in multiple segments, wherein The jumpers included in one jumper layer among the plurality of jumper layers respectively supply power to the resistor heating elements included in one resistor heating element layer among the plurality of resistor heating element layers, The heater layer has a ceramic insulating layer with a thickness of 2 μm or more and 50 μm or less between the metal layers, and the ceramic insulating layer is an aerosol deposition film.

2. The electrostatic chuck heater according to claim 1, wherein the withstand voltage of each layer of the ceramic insulating layer is 200 VAC or more.

3. The electrostatic chuck heater according to claim 1 or 2, wherein the porosity of the ceramic insulating layer is 0.5% or less.

4. The electrostatic chuck heater according to claim 1 or 2, wherein the heater layer has 3 or more layers of the ceramic insulating layer.

5. The electrostatic chuck heater according to claim 1 or 2, wherein the metal layer is an aerosol deposition film.

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