Electrostatic chuck and plasma processing apparatus including the same

Abstract

An electrostatic chuck capable of accurately controlling a temperature of a peripheral region of a substrate and a plasma processing apparatus including the electrostatic chuck are disclosed. The electrostatic chuck configured to support a substrate in a plasma processing apparatus includes: a metal base plate in which a coolant flow path is formed; and the ceramic tray is combined to the upper surface of the metal bottom plate. The bonding surface of the metal base plate has a protruding portion, and the bonding surface of the ceramic tray has a portion corresponding in shape to the protruding portion. The protruding portion is formed on a peripheral portion of the metal base plate to protrude more upward than a central portion of the metal base plate. An outer coolant flow path adjacent to the protruding portion has a region that expands more upward than a center-side coolant flow path located at the center portion.

Description

Technical Field

[0001] The present disclosure relates to an electrostatic chuck and a plasma processing apparatus including the electrostatic chuck. Background Art

[0002] A semiconductor manufacturing process is a process of manufacturing semiconductor devices on a substrate (e.g., a wafer) and includes, for example, lithography, deposition, etching, ion implantation, and cleaning. To perform each manufacturing process, semiconductor manufacturing devices for performing each process are provided in a clean room of a semiconductor manufacturing facility, and each process is performed on a substrate loaded in the semiconductor manufacturing device.

[0003] Processes using plasma, such as etching and deposition, are widely used in semiconductor manufacturing processes. The plasma processing process is implemented in the following manner: a substrate is located in a lower portion of a plasma processing space, a fluid for plasma processing is supplied, and a voltage is applied through electrodes located in an upper portion and a lower portion of the plasma processing space.

[0004] In the plasma processing process, the distribution of plasma and the reaction rate of the substrate (e.g., etching rate) are affected by temperature. Therefore, it is important to maintain a uniform temperature throughout the entire area of the substrate in the plasma processing process. However, temperature control of the peripheral area of the substrate is more difficult than temperature control of the central area of the substrate. Therefore, precise temperature control of the peripheral area of the substrate is required. Summary of the Invention

[0005] Accordingly, the present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide an electrostatic chuck capable of precisely controlling the temperature of the peripheral area of a substrate and a plasma processing apparatus including the electrostatic chuck.

[0006] The object to be achieved by the present disclosure is not limited to the above object, and other objects not mentioned herein will be clearly understood by those skilled in the art from the following description.

[0007] According to an embodiment of the present disclosure, an electrostatic chuck configured to support a substrate in a plasma processing apparatus includes: a metal bottom plate in which a coolant flow path is formed; and a ceramic puck coupled to an upper surface of the metal bottom plate. A surface of the metal bottom plate that contacts the ceramic puck has a protruding portion, and a surface of the ceramic puck that contacts the metal bottom plate has a portion corresponding in shape to the protruding portion. The protruding portion is formed on a peripheral portion of the metal bottom plate to protrude more upward than a central portion of the metal bottom plate. The coolant flow path includes a central side coolant flow path located at the central portion of the metal bottom plate and an outer coolant flow path positioned adjacent to the protruding portion, and the outer coolant flow path has a region that extends more upward than the central side coolant flow path.

[0008] In an embodiment of the present disclosure, the metal bottom plate and the ceramic puck may be directly coupled to each other.

[0009] In an embodiment of the present disclosure, the metal bottom plate and the ceramic puck may be coupled to each other by brazing or diffusion bonding.

[0010] In an embodiment of the present disclosure, the metal bottom plate may be made of a metal matrix composite material having the same coefficient of thermal expansion as the material of the ceramic puck.

[0011] In an embodiment of the present disclosure, a top surface of the outer coolant flow path may be located at a higher position than a top surface of the central side coolant flow path.

[0012] In an embodiment of the present disclosure, a top surface of the outer coolant flow path may be located at a higher position than a central portion of a contact surface between the metal bottom plate and the ceramic puck.

[0013] In an embodiment of the present disclosure, an oxide film may be formed on an outer surface of the metal bottom plate.

[0014] In an embodiment of the present disclosure, the oxide film may be made of zirconia (ZrO 2 )

[0015] In an embodiment of the present disclosure, the oxide film may be formed on outer surfaces of the metal bottom plate and the ceramic puck.

[0016] According to another embodiment of the present disclosure, the electrostatic chuck configured to support a substrate in a plasma processing apparatus includes: a metal bottom plate made of metal, in which a coolant flow path is formed; and a ceramic tray, the ceramic tray being bonded to the upper surface of the metal bottom plate. The surface of the metal bottom plate in contact with the ceramic tray has a protruding portion, and the surface of the ceramic tray in contact with the metal bottom plate has a portion corresponding to the protruding portion in shape. The protruding portion includes: a central side protruding portion formed at a position corresponding to the central portions of the metal bottom plate and the ceramic tray; and an outer protruding portion formed at a position corresponding to the peripheral portions of the metal bottom plate and the ceramic tray. The coolant flow path includes a central side coolant flow path located at the central portion of the metal bottom plate and an outer coolant flow path positioned adjacent to the outer protruding portion, the outer coolant flow path having a region extending more upward than the central side coolant flow path.

[0017] According to another embodiment of the present disclosure, a plasma processing apparatus includes: an electrostatic chuck configured to support a substrate using electrostatic force; and a coolant supply device configured to supply coolant to the electrostatic chuck. The electrostatic chuck includes: a metal bottom plate in which a coolant flow path is formed; a ceramic tray bonded to the upper surface of the metal bottom plate; and a coolant supply flow path configured to supply coolant to the coolant flow path.

[0018] The surface of the metal bottom plate in contact with the ceramic tray has a protruding portion, and the surface of the ceramic tray in contact with the metal bottom plate has a portion corresponding to the protruding portion in shape. The protruding portion is formed on the peripheral portion of the metal bottom plate to protrude more upward than the central portion of the metal bottom plate.

[0019] The coolant flow path includes: an outer coolant flow path formed at a position adjacent to the protruding portion in the metal bottom plate; and a central side coolant flow path formed at a position more inward than the outer coolant flow path in the metal bottom plate.

[0020] The coolant supply flow path includes: an outer coolant supply flow path connected to the outer coolant flow path; and a central side coolant supply flow path connected to the central side coolant flow path.

[0021] The coolant supply device includes: a coolant source configured to store coolant to be supplied to the outer coolant supply flow path and the central side coolant supply flow path; and a flow rate controller configured to separately control the flow rate of the coolant supplied to each of the outer coolant supply flow path and the central side coolant supply flow path. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings incorporated in this specification illustrate exemplary embodiments and are used to further illustrate the technical idea of the present disclosure in combination with the following detailed description of the exemplary embodiments, and the present disclosure should not be construed as being limited to the content shown in such drawings. In the drawings:

[0023] Figure 1 A plasma processing apparatus is shown in which protruding portions are formed on the peripheral portion of the surface of a metal bottom plate bonded to the surface of a ceramic tray;

[0024] Figure 2 A plasma processing apparatus is shown in which protruding portions are formed on the peripheral portion of the surface of a metal bottom plate bonded to the surface of a ceramic tray, and an oxide film is formed on the outer surface of the metal bottom plate;

[0025] Figure 3 A plasma processing apparatus is shown in which protruding portions are formed on the peripheral portion of the surface of a metal bottom plate bonded to the surface of a ceramic tray, and an oxide film is formed on the outer surfaces of the metal bottom plate and the ceramic tray;

[0026] Figure 4 A plasma processing apparatus is shown in which protruding portions are formed on the surface of a metal bottom plate bonded to the surface of a ceramic tray;

[0027] Figure 5 A plasma processing apparatus is shown in which protruding portions are formed on the surface of a metal bottom plate bonded to the surface of a ceramic tray, and an oxide film is formed on the outer surface of the metal bottom plate; and

[0028] Figure 6 A plasma processing apparatus is shown in which protruding portions are formed on the surface of a metal bottom plate bonded to the surface of a ceramic tray, and an oxide film is formed on the outer surfaces of the metal bottom plate and the ceramic tray. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings so that those skilled in the art can easily implement these embodiments. However, the present disclosure can be implemented in many different forms and should not be construed as being limited to these embodiments set forth herein.

[0030] Parts that are not relevant to the description of the present disclosure will be omitted to clearly describe the present disclosure, and throughout the specification, the same or similar constituent elements will be indicated by the same reference numerals.

[0031] In addition, constituent elements having the same configuration in several embodiments will be assigned the same reference numerals and described only in the representative embodiment, and only the constituent elements different from those in the representative embodiment will be described in other embodiments.

[0032] Throughout the specification, when a constituent element is said to be "connected", "coupled", or "joined" to another constituent element, the constituent element and the other constituent element may be "directly connected", "directly coupled", or "directly joined" to each other, or may be "indirectly connected", "indirectly coupled", or "indirectly joined" to each other, with one or more intermediate elements inserted therebetween. In addition, throughout the specification, when a constituent element is said to "include", "comprise", or "have" another constituent element, the constituent element should not be construed as excluding other elements as long as there is no special conflicting description, and the constituent element may include at least one other element.

[0033] Unless otherwise defined, all terms (including technical or scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art. Terms such as those defined in a common dictionary should be construed as having the same meaning as the terms in the relevant technical background, and should not be construed as having an ideal or overly formal meaning unless clearly defined in this specification.

[0034] The present disclosure relates to an electrostatic chuck 10 and a plasma processing apparatus 1 including the electrostatic chuck 10, and more particularly, to an electrostatic chuck 10 for supporting a substrate W in the plasma processing apparatus 1 and a structure thereof capable of precisely controlling the temperature of the peripheral region of the substrate W.

[0035] The plasma processing apparatus 1 is a device for performing plasma processing (e.g., dry etching) on a substrate W. When the substrate W is loaded in the plasma processing apparatus 1, radio frequency (RF) is applied to the upper electrode and the lower electrode to generate an electromagnetic field, and the processing gas supplied to the substrate W is converted into a plasma state due to the electromagnetic field and reacts with a specific material of the substrate W. The substrate W that has undergone plasma processing for a certain period of time is transferred to the outside of the plasma processing apparatus 1, and subsequent processing steps are performed.

[0036] Figure 1 is a view showing the plasma processing apparatus 1 according to the present disclosure. Refer to Figure 1, the plasma processing apparatus 1 includes: an electrostatic chuck 10 configured to support a substrate using electrostatic force; and a coolant supply device 20 configured to supply coolant to the electrostatic chuck 10.

[0037] The electrostatic chuck 10 includes a metal base plate 120 in which a coolant flow path 122 is formed, a ceramic tray 110 coupled to an upper portion of the metal base plate 120, and a coolant supply flow path 124 configured to supply coolant to the coolant flow path 122.

[0038] The surface of the metal base plate 120 that contacts the ceramic tray 110 has a protruding portion 1000, and the surface of the ceramic tray 110 that contacts the metal base plate 120 has a portion corresponding in shape to the protruding portion 1000. The protruding portion 1000 is formed on the peripheral portion of the metal base plate 120 to protrude more upward than the central portion of the metal base plate 120. Refer to Figure 1 , the peripheral portion of the surface of the metal base plate 120 coupled to the surface of the ceramic tray 110 protrudes upward. As Figure 1 shown, the two bonding surfaces are not flat, and a part thereof protrudes, and this part is called a "protruding portion". The metal base plate 120 and the ceramic tray 110 may have the following structure: wherein the bonding surface of the structure is not flat, that is, the heights of the bonding surfaces are inconsistent (non-flat structure). In the case where the protruding portion 1000 is formed as shown in Figure 1 shown, the metal base plate 120 and the ceramic tray 110 are easily aligned with each other when directly bonded to each other. In addition, the bonding area between the metal base plate 120 and the ceramic tray 110 increases, and thus sufficient bonding strength between them can be ensured.

[0039] Although Figure 1 shows the case where the protruding portion 1000 is formed only on the peripheral portion of the metal base plate 120, the non-flat structure can also be applied to the central portion of the metal base plate 120. Figures 1 to 3 shows the case where an outer protruding portion 1000B is formed on the peripheral portion of the metal base plate 120. Figures 4 to 6 shows the case where a central protruding portion 1000A is formed on the central portion of the metal base plate 120 and an outer protruding portion 1000B is formed on the peripheral portion of the metal base plate 120. Refer to Figure 1 , the protruding height H2 of the outer protruding portion 1000B is greater than the height H1 of the central portion of the surface of the metal base plate 120 bonded to the surface of the ceramic tray 110.

[0040] The metal base plate 120 and the ceramic tray 110 are directly bonded to each other. The metal base plate 120 and the ceramic tray 110 can be bonded to each other by brazing or diffusion bonding. Generally, the metal base plate 120 and the ceramic tray 110 are bonded to each other through a bonding layer interposed therebetween. In the case where a bonding layer is provided, the bonding layer may be damaged by plasma. In order to prevent the bonding layer from being damaged by plasma, an annular sealing member is provided on the outer side of the bonding layer. However, since the bonding layer is still very likely to be damaged even if the sealing member is provided, continuous maintenance of the bonding layer is required, which reduces the operability of the plasma processing apparatus 1. Therefore, the present disclosure proposes a structure for directly bonding the metal base plate 120 and the ceramic tray 110 to each other without a bonding layer. According to the present disclosure, the above non-planar structure (i.e., the protruding portion 1000) can be adopted so that the bonding surfaces of the metal substrate 120 and the ceramic tray 110 are stably and firmly bonded to each other.

[0041] The metal base plate 120 may be made of a metal matrix composite material having the same coefficient of thermal expansion as the material of the ceramic tray 110. In the present disclosure in which the metal base plate 120 and the ceramic tray 110 are directly bonded to each other, if the materials of the metal base plate 120 and the ceramic tray 110 have different coefficients of thermal expansion, the bonding strength between their bonding surfaces may become weak. Therefore, the metal base plate 120 is made of a metal matrix composite material that is processed to have the same coefficient of thermal expansion as the material of the ceramic tray 110, rather than being made of common aluminum (Al). Therefore, regardless of various temperature changes in the plasma processing apparatus 1, sufficient bonding strength between the bonding surfaces of the metal base plate 120 and the ceramic tray 110 can be ensured.

[0042] Reference Figure 1 , the outer coolant flow path 122B adjacent to the protruding portion 1000 has a region that extends more upward than the central side coolant flow path 122A located at the central portion of the metal base plate 120. The outer coolant flow path 122B is a coolant flow path formed inside the outer protruding portion 1000B. The outer coolant flow path 122B can extend upward in a region that expands upward through the outer protruding portion 1000B. That is, the top surface CH2 of the outer coolant flow path 122B can be located at a higher position than the top surface CH1 of the central side coolant flow path 122A. The top surface CH2 of the outer coolant flow path 122B can be located at a higher position than the central portion (denoted as H1) of the contact surface between the metal base plate 120 and the ceramic tray 110. Although not shown in detail in the drawings, a sensor for measuring the temperature of the substrate W can be provided at the outer protruding portion 1000B to more accurately measure the temperature of the peripheral portion of the substrate W.

[0043] The coolant flow path 122 includes an outer coolant flow path 122B formed at a position adjacent to the protruding portion 1000 in the metal base plate 120, and a central side coolant flow path 122A formed at a position more inward than the outer coolant flow path 122B in the metal base plate 120 (i.e., a position adjacent to the central portion of the metal base plate 120).

[0044] The coolant supply flow path 124 includes an outer coolant supply flow path 124B connected to the outer coolant flow path 122B, and a central side coolant supply flow path 124A connected to the central side coolant flow path 122A.

[0045] The coolant supply device 20 supplies coolant to the coolant flow path 122 formed in the electrostatic chuck 10. The coolant supply device 20 includes: a coolant source 210 configured to store the coolant to be supplied to the outer coolant supply flow path 124B and the central side coolant supply flow path 122A; and a flow rate controller 220 configured to separately control the flow rate of the coolant supplied to each of the outer coolant supply flow path 124B and the central side coolant supply flow path 122A.

[0046] The coolant source 210 includes an outer coolant source 210B connected to the outer coolant supply flow path 124B, and a central side coolant source 210A connected to the central side coolant supply flow path 124A. The outer coolant source 210B and the central side coolant source 210A may store different types of coolant. Since the types of coolant supplied to the central side coolant flow path 122A and the outer coolant flow path 122B are different from each other, the temperature control characteristics can be managed differently between the central portion and the peripheral portion of the electrostatic chuck 10.

[0047] The coolant source 210 can temporarily store the coolant supplied from the outside and can supply the coolant at a set flow rate (pressure). The outer coolant source 210B and the central side coolant source 210A of the coolant source 210 may be implemented as a single integral tank, or may be provided separately from each other. A flow rate control valve configured to allow or interrupt the supply of the coolant and control the flow rate of the coolant may be provided on the flow path between the coolant source 210 and the coolant supply flow path 124. The flow rate controller 220 can control the flow rate of the coolant supplied from the coolant source 210 to the coolant supply flow path 124 through the flow rate control valve.

[0048] The flow rate controller 220 may perform control such that the flow rates of the coolant supplied to the outer coolant supply flow path 124B and the center-side coolant supply flow path 122A are different from each other. For example, when the peripheral portion of the substrate W needs to be rapidly cooled, the flow rate controller 220 may perform control such that the flow rate of the coolant supplied to the outer coolant supply flow path 124B is greater than the flow rate of the coolant supplied to the center-side coolant supply flow path 122A.

[0049] Figure 2 The plasma processing apparatus 1 is shown, in which the protruding portion 1000 is formed on the peripheral portion of the surface of the metal base plate 120 bonded to the surface of the ceramic tray 110, and the oxide film 130 is formed on the outer surface of the metal base plate 120. Refer to Figure 2 , the oxide film 130 is formed on the outer surface of the metal base plate 120. The oxide film 130 is made of zirconia (ZrO 2 ). Commonly used alumina (Al 2 O 3 ) has a thermal conductivity of 32 W / mK and enables rapid heat exchange. However, the high thermal conductivity allows external heat to be transferred to the electrostatic chuck 10, making it difficult to control the temperature of the electrostatic chuck 10. According to the present disclosure, since zirconia (ZrO 2 ) has a thermal conductivity of 2 W / mK, the oxide film 130 has a low heat exchange rate with the outside, thereby maintaining the temperature of the electrostatic chuck 10 at a constant level. With the oxide film 130 made of zirconia (ZrO 2 ), the temperature of the peripheral portion of the substrate W can be precisely controlled. The oxide film 130 prevents the metal base plate 120 of the metal material from being plasma-etched.

[0050] Figure 3 The plasma processing apparatus 1 is shown, in which the protruding portion 1000 is formed on the peripheral portion of the surface of the metal base plate 120 bonded to the surface of the ceramic tray 110, and the oxide film 130 is formed on the outer surfaces of the metal base plate 120 and the ceramic tray 110. The oxide film 130 may be formed on the outer surfaces of the metal base plate 120 and the ceramic tray 110. Compared with Figure 2 the configuration shown, the oxide film 130 extends so as to be provided on the outer surface of the ceramic tray 110 as well as the outer surface of the metal base plate 120. The oxide film 130 is made of zirconia (ZrO 2)It is made. Since the oxide film 130 is formed on the outer surface of the ceramic tray 110 and the outer surface of the metal base plate 120, the strength of the bonding surface between the metal base plate 120 and the ceramic tray 110 can be increased. When the metal base plate 120 and the ceramic tray 110 are directly bonded to each other, the bonding strength at the peripheral region of the bonding surface may be low. However, the oxide film 130 can increase the bonding strength at the peripheral region of the bonding surface.

[0051] Figure 4 FIG. 1 shows a plasma processing apparatus 1 in which a protruding portion 1000 is formed on the surface of a metal base plate 120 bonded to the surface of a ceramic tray 110. Compared with Figure 1 the configuration shown, the protruding portion 1000 is formed on the central portion and the peripheral portion of the metal base plate 120. That is, the protruding portion 1000 includes a central-side protruding portion 1000A formed at a position corresponding to the central portion of the metal base plate 120 and the ceramic tray 110, and an outer protruding portion 1000B formed at a position corresponding to the peripheral portion of the metal base plate 120 and the ceramic tray 110. In the metal base plate 120, an outer coolant flow path 122B adjacent to the outer protruding portion 1000B has a region that extends more upward than a central-side coolant flow path 122A located at the central portion of the metal base plate 120.

[0052] As Figure 4 shown, in the case where an uneven structure is applied to the entire region of the bonding surface between the metal base plate 120 and the ceramic tray 110, the metal base plate 120 and the ceramic tray 110 are easily aligned with each other when directly bonded to each other. In addition, the bonding area between the metal base plate 120 and the ceramic tray 110 is increased, so sufficient bonding strength between them can be ensured.

[0053] Figure 5 FIG. 2 shows a plasma processing apparatus 1 in which a protruding portion 1000 is formed on the surface of a metal base plate 120 bonded to the surface of a ceramic tray 110, and an oxide film 130 is formed on the outer surface of the metal base plate 120. Compared with Figure 4 the configuration shown, the oxide film 130 is formed on the outer surface of the metal base plate 120. The oxide film 130 is made of zirconia (ZrO 2 )). With the oxide film 130 made of zirconia (ZrO 2 ), the temperature of the peripheral portion of the substrate W can be precisely controlled. The oxide film 130 prevents the metal base plate 120 of the metal material from being etched by plasma.

[0054] Figure 6shows a plasma processing apparatus 1, in which a protruding portion 1000 is formed on the surface of a metal bottom plate 120 bonded to the surface of a ceramic tray 110, and an oxide film 130 is formed on the outer surfaces of the metal bottom plate 120 and the ceramic tray 110. Compared with Figure 5 the configuration shown, the oxide film 130 extends so as to be provided on the outer surface of the ceramic tray 110 and the outer surface of the metal bottom plate 120. The oxide film 130 is made of zirconia (ZrO 2 ). Since the oxide film 130 is formed on the outer surface of the ceramic tray 110 and the outer surface of the metal bottom plate 120, the strength of the bonding surface between the metal bottom plate 120 and the ceramic tray 110 can be increased. In the case where the metal bottom plate 120 and the ceramic tray 110 are directly bonded to each other, the bonding strength at the peripheral region of the bonding surface may be low. However, the oxide film 130 can increase the bonding strength at the peripheral region of the bonding surface.

[0055] As is apparent from the above description, according to the present disclosure, since the outer coolant flow path having an extended region is formed adjacent to the protruding portion formed on the peripheral portion of the bonding surface between the ceramic tray and the metal bottom plate, the temperature of the peripheral portion of the substrate can be precisely controlled.

[0056] The effects achievable by the present disclosure are not limited to the above effects, and those skilled in the art will clearly understand other effects not mentioned herein from the present specification and the drawings.

[0057] Although the preferred embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the present disclosure.

[0058] The scope of the present disclosure should be defined only by the appended claims, and all technical concepts within the scope of equivalents of the claims should be construed as falling within the scope of the present disclosure.

Claims

1. An electrostatic chuck configured to support a substrate in a plasma processing apparatus, the electrostatic chuck comprising: a metal base plate having a coolant flow path formed therein; as well as a ceramic tray bonded to an upper surface of the metal base plate, wherein the surface of the metal bottom plate in contact with the ceramic tray has a protruding portion, and the surface of the ceramic tray in contact with the metal bottom plate has a portion corresponding in shape to the protruding portion, wherein the protruding portion is formed on a peripheral portion of the metal bottom plate so as to protrude upward more than a central portion of the metal bottom plate, and The coolant flow path includes: a center-side coolant flow path located at the center portion of the metal base plate; as well as An outer coolant flow path is located adjacent to the protruding portion, the outer coolant flow path having a region that expands more upward than the center-side coolant flow path.

2. The electrostatic chuck of claim 1, wherein the metal base plate and the ceramic tray are directly bonded to each other. 3 . The electrostatic chuck of claim 2 , wherein the metal base plate and the ceramic tray are bonded to each other by brazing or diffusion bonding.

4. The electrostatic chuck of claim 1, wherein the metal base plate is made of a metal matrix composite material having the same coefficient of thermal expansion as the material of the ceramic tray. 5 . The electrostatic chuck of claim 1 , wherein a top surface of the outer coolant flow path is located at a higher position than a top surface of the center-side coolant flow path. 6 . The electrostatic chuck of claim 1 , wherein a top surface of the outer coolant flow path is located at a higher position than a central portion of a contact surface between the metal base plate and the ceramic tray. 7 . The electrostatic chuck of claim 1 , further comprising an oxide film formed on an outer side surface of the metal base plate.

8. The electrostatic chuck according to claim 7, wherein the oxide film is made of zirconium oxide (ZrO2). 9 . The electrostatic chuck of claim 7 , wherein the oxide film is formed on outer side surfaces of the metal base plate and the ceramic tray.

10. An electrostatic chuck configured to support a substrate in a plasma processing apparatus, the electrostatic chuck comprising: a metal base plate having a coolant flow path formed therein; as well as a ceramic tray bonded to an upper surface of the metal base plate, wherein the surface of the metal bottom plate in contact with the ceramic tray has a protruding portion, and the surface of the ceramic tray in contact with the metal bottom plate has a portion corresponding in shape to the protruding portion, The protruding parts include: a central side protrusion formed at a position corresponding to central portions of the metal bottom plate and the ceramic tray; and an outer protrusion formed at a position corresponding to the outer periphery of the metal bottom plate and the ceramic tray, and The coolant flow path includes: a center-side coolant flow path located at a center portion of the metal base plate; and An outer coolant flow path is located adjacent to the outer protruding portion, the outer coolant flow path having a region that expands more upward than the center-side coolant flow path.

11. The electrostatic chuck of claim 10, wherein the metal base plate and the ceramic tray are directly bonded to each other.

12. The electrostatic chuck of claim 11, wherein the metal base plate and the ceramic tray are bonded to each other by brazing or diffusion bonding.

13. The electrostatic chuck of claim 11, wherein the metal base plate is made of a metal matrix composite material having the same coefficient of thermal expansion as the material of the ceramic tray.

14. The electrostatic chuck of claim 11, wherein a top surface of the outer coolant flow path is located at a higher position than a top surface of the center-side coolant flow path. 15 . The electrostatic chuck of claim 11 , wherein a top surface of the outer coolant flow path is located at a higher position than a central portion of a contact surface between the metal base plate and the ceramic tray. 16 . The electrostatic chuck of claim 11 , further comprising an oxide film formed on an outer side surface of the metal base plate.

17. The electrostatic chuck of claim 16, wherein the oxide film is made of zirconium oxide (ZrO2).

18. The electrostatic chuck of claim 16, wherein the oxide film is formed on outer side surfaces of the metal base plate and the ceramic tray.

19. A plasma processing apparatus comprising: an electrostatic chuck configured to support a substrate using electrostatic forces; as well as a coolant supply device configured to supply coolant to the electrostatic chuck, The electrostatic chuck comprises: a metal base plate having a coolant flow path formed therein; a ceramic tray bonded to an upper surface of the metal base plate; and a coolant supply flow path configured to supply coolant to the coolant flow path; wherein the surface of the metal bottom plate in contact with the ceramic tray has a protruding portion, and the surface of the ceramic tray in contact with the metal bottom plate has a portion corresponding in shape to the protruding portion, wherein the protruding portion is formed on a peripheral portion of the metal bottom plate so as to protrude upward more than a central portion of the metal bottom plate, The coolant flow path includes: an outer coolant flow path formed in the metal base plate at a position adjacent to the protruding portion; and a center-side coolant flow path formed in the metal base plate at a position further inward than the outer coolant flow path, The coolant supply flow path comprises: an external coolant supply flow path connected to the external coolant flow path; and a center-side coolant supply flow path connected to the center-side coolant flow path, and The coolant supply device comprises: a coolant source configured to store a coolant to be supplied to the outer coolant supply flow path and the center-side coolant supply flow path; and A flow rate controller configured to individually control a flow rate of coolant supplied to each of the outer coolant supply flow path and the center-side coolant supply flow path.

20. The plasma processing apparatus of claim 19, wherein the coolant source comprises: an external coolant source connected to the external coolant supply flow path; as well as a center-side coolant source connected to the center-side coolant supply flow path, and The outer coolant source and the center-side coolant source store different types of coolants.

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