Member for semiconductor manufacturing device

Abstract

A wafer placement table 10 comprises: a ceramic plate 20 having a wafer placement surface 21 on an upper surface, and having a built-in electrostatic electrode 22; a base plate 50 provided on a lower surface of the ceramic plate 20 and having a built-in refrigerant flow path 52; and a gas passage 24 provided so as to extend to the wafer placement surface 21 from the lower surface of the base plate 50. The wafer placement table 10 further comprises: a heater electrode 30 serving as an internal electrode; and a switching unit 35 connected to the heater electrode 30 and configured to be capable of switching between whether or not the heater electrode 30 is electrically connected to the electrostatic electrode 22. The heater electrode 30 is provided inside the ceramic plate 20 so as to be positioned around the gas passage 24 below the electrostatic electrode 22 and so as not to be exposed on the inner wall of the gas passage 24. The base plate 50 also serves as a bias electrode. The bias electrode is provided electrically independent of the electrostatic electrode 22, and a bias voltage is applied when generating plasma above the wafer mounting surface 21.

Description

Semiconductor manufacturing equipment components

[0001] The present invention relates to a member for a semiconductor manufacturing device.

[0002] Conventionally, a semiconductor manufacturing equipment component has been known that includes a ceramic plate having a wafer mounting surface on its upper surface and a built-in electrode, a base plate provided on the lower surface of the ceramic plate, and a gas passageway extending from the lower surface of the base plate to the wafer mounting surface of the ceramic plate. Patent Document 1 discloses such a semiconductor manufacturing equipment component, in which a cylindrical shield electrode portion is provided around the gas passageway in the ceramic plate. The cylindrical shield electrode portion functions to shield the interior space of the gas passageway from the influence of an electric field generated around the electrostatic electrode when a DC voltage is applied to the electrostatic electrode. This prevents or reduces the occurrence of abnormal discharge in the gas passageway.

[0003] International Publication No. 2023 / 095707

[0004] However, in Patent Document 1, if the shielding by the shield electrode portion is insufficient, it may not be possible to prevent the occurrence of abnormal discharge in the gas passage.

[0005] The present invention has been made to solve the above-mentioned problems, and its main object is to prevent or reduce the occurrence of abnormal discharge in a passageway using a different principle from the conventional one.

[0006] [1] A semiconductor manufacturing equipment member of the present invention comprises: a ceramic plate having a wafer mounting surface on its upper surface and incorporating an electrostatic electrode; a base plate provided on the underside of the ceramic plate and incorporating a coolant flow path; a passage provided from the underside of the base plate to the wafer mounting surface of the ceramic plate; an internal electrode provided inside the ceramic plate and positioned below the electrostatic electrode around the passage and not exposed to the inner wall of the passage; a switching unit connected to the internal electrode and configured to be able to switch whether the internal electrode is electrically connected to the electrostatic electrode; and a bias electrode provided at the same height as or below the internal electrode and electrically independent of the electrostatic electrode, to which a bias voltage is applied when plasma is generated above the wafer mounting surface.

[0007] In this semiconductor manufacturing equipment component, the internal electrode is located below the electrostatic electrode and inside the ceramic plate, surrounding the passageway, without being exposed to the inner wall of the passageway. A switching unit is connected to the internal electrode, allowing the internal electrode to be electrically connected to or disconnected from the electrostatic electrode. When a DC voltage is applied to the electrostatic electrode and a bias voltage is applied to the bias electrode, a vertical potential gradient is generated in the interior space of the passageway. In this invention, by electrically connecting the internal electrode located below the electrostatic electrode to the electrostatic electrode and setting it at the same potential as the electrostatic electrode, the vertical distance over which the potential gradient occurs can be shortened compared to when the internal electrode is not electrically connected to the electrostatic electrode. As a result, even if electrons ionized from atoms or molecules of the thermal conduction gas are accelerated by the potential gradient, they are not sufficiently accelerated and do not have sufficient energy, thereby preventing arc discharge. Therefore, abnormal discharge in the passageway can be prevented or reduced based on a principle different from the conventional principle of shielding the influence of the electric field generated around the electrostatic electrode. Furthermore, in this invention, when it is not necessary to maintain the internal electrode at the same potential as the electrostatic electrode, such as when plasma is not being generated or a bias voltage is not being applied, the internal electrode can be switched and used for other purposes.

[0008] In this specification, "upper" and "lower" do not represent absolute positional relationships, but rather relative positional relationships. Therefore, depending on the orientation of the semiconductor manufacturing equipment component, "upper" and "lower" may become "lower" and "upper," "left" and "right," or "front" and "rear." Furthermore, examples of "passages" include gas passages and lift pin holes.

[0009] [2] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [1] above), the internal electrode may be a heater electrode that is connected to a heater power supply and generates heat, and the switching unit may be configured to switch between electrically connecting the heater electrode to the electrostatic electrode or to the heater power supply. In this way, when it is not necessary to maintain the internal electrode at the same potential as the electrostatic electrode, the connection of the internal electrode can be switched to the heater power supply and used as a heater. This makes it possible, for example, to maintain or raise the temperature of a wafer placed on the wafer placement surface to a desired temperature.

[0010] [3] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [2] above), the heater electrode may be wired so as to extend from one of a pair of terminals to the other of the pair of terminals, and may be located around the passage so as to branch and merge around the passage.

[0011] [4] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [3] above), the heater electrodes may form a parallel circuit around the passage.

[0012] [5] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member according to any one of [1] to [4] above), the base plate may also serve as the bias electrode. This eliminates the need to provide a bias electrode separately from the base plate.

[0013] [6] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member according to any one of [1] to [5] above), the bias electrode may be built into the ceramic plate.

[0014] [7] In the semiconductor manufacturing equipment component of the present invention (the semiconductor manufacturing equipment component according to any one of [1] to [6] above), the passage may be connected to a heat transfer gas supply source. In this case, atoms or molecules of the heat transfer gas are ionized in the internal space of the passage to generate electrons, and these electrons are likely to collide with other atoms or molecules, making it highly significant to apply the present invention.

[0015] [8] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member according to any one of [1] to [7] above), the base plate may also serve as a source electrode to which a source voltage is applied when generating plasma above the wafer-mounting surface. This eliminates the need to provide a source electrode separate from the base plate.

[0016] 1A and 1B are a plan view and a perspective view with a cross-sectional view of the wafer mounting table 10, respectively; a partial cross-sectional view of the wafer mounting table 10; a cross-sectional view of the wafer mounting table 10 cut along a plane including the electrostatic electrode 22; a cross-sectional view of the wafer mounting table 10 cut along a plane including the heater electrode 30; and a partial cross-sectional view of another embodiment.

[0017] A preferred embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a plan view of a wafer mounting table 10, Fig. 2 is a perspective view with a cross-sectional view of the wafer mounting table 10, Fig. 3 is a partial cross-sectional view of the wafer mounting table 10, Fig. 4 is a cross-sectional view of the wafer mounting table 10 taken along a plane including the electrostatic electrode 22, and Fig. 5 is a cross-sectional view of the wafer mounting table 10 taken along a plane including the heater electrode 30. Note that the seal band 21a and the small circular protrusions 21b are omitted in Figs. 2 and 3. Also, the heater electrode 30 is omitted in Fig. 2, and the electrode terminal 26, power supply member 58, and power supply member mounting hole 54 are omitted in Fig. 3.

[0018] The wafer mounting table 10 is an example of a semiconductor manufacturing equipment component of the present invention, and as shown in FIG. 2, includes a ceramic plate 20, a base plate 50, a bonding layer 60, a power supply member placement hole 54, and a gas passage 24.

[0019] The ceramic plate 20 is a circular ceramic plate (e.g., 300 mm in diameter and 5 mm in thickness) made of alumina sintered body, aluminum nitride sintered body, or the like. The upper surface of the ceramic plate 20 serves as a wafer mounting surface 21. The ceramic plate 20 incorporates an electrostatic electrode 22. As shown in FIG. 1 , a seal band 21a is formed along the outer edge of the wafer mounting surface 21, and a plurality of small circular protrusions 21b are formed on the entire inner surface of the seal band 21a. The seal band 21a and the small circular protrusions 21b have the same height, e.g., several micrometers to several tens of micrometers. The electrostatic electrode 22 is a circular mesh flat electrode connected to a DC power supply 70 via a power supply member 58. When a DC voltage is applied to the electrostatic electrode 22, the wafer W is attracted and fixed to the wafer mounting surface 21 (specifically, the upper surfaces of the seal band 21a and the small circular protrusions 21b) by electrostatic attraction. When the DC voltage application is released, the wafer W is released from the wafer mounting surface 21.

[0020] As shown in Figures 3 and 5, a heater electrode 30 is provided inside the ceramic plate 20. The heater electrode 30 corresponds to an internal electrode of the present invention and is provided below the electrostatic electrode 22. The heater electrode 30 is provided inside the ceramic plate 20 so as to surround the gas passage 24 and be positioned around the gas passage 24 without being exposed to the inner wall of the gas passage 24. Specifically, as shown in Figure 5, the heater electrode 30 is wired from one 31a of a pair of terminals 31 disposed on the outer periphery of the ceramic plate 20, extending over almost the entire area of ​​the ceramic plate 20, and then to the other 31b of the pair of terminals 31 disposed on the outer periphery of the ceramic plate 20. The heater electrode 30 has parallel portions 32 connected in parallel by branching at branch points 32a and joining at joining points 32b so as to be positioned around the gas passage 24 and surrounding the gas passage 24. The heater electrode 30 is composed of, for example, a resistance heating element and generates heat when connected to a heater power supply 80, which is a DC power supply. The resistance heating element may be composed primarily of a high-melting-point metal or its carbide. Examples of high-melting-point metals include tungsten, molybdenum, tantalum, platinum, rhenium, hafnium, and alloys thereof. Examples of high-melting-point metal carbides include tungsten carbide and molybdenum carbide. The heater electrode 30 may be ribbon-shaped (flat and elongated). The ribbon-shaped heater electrode 30 may be formed by printing a paste containing a high-melting-point metal or its carbide. The paste may contain ceramic. The heater electrode 30 may be coil-shaped.

[0021] A switching unit 35 is connected to the heater electrode 30. The switching unit 35 is configured to switch whether the heater electrode 30 is electrically connected to the electrostatic electrode 22 or not. Here, the switching unit 35 has a single-pole, double-throw (SPDT) switch and is configured to switch whether the heater electrode 30 is electrically connected to the electrostatic electrode 22 or to the heater power supply 80. When the heater electrode 30 is electrically connected to the electrostatic electrode 22, the heater electrode 30 has the same potential as the electrostatic electrode 22 and functions as a potential gradient adjusting electrode that adjusts the potential gradient in the gas passage 24. When the heater electrode 30 is connected to the heater power supply 80, the heater electrode 30 generates heat and functions as a heater electrode. Note that when the heater electrode 30 is connected to the heater power supply 80, the heater electrode 30 is connected so that a closed circuit is formed between the heater power supply 80 and ground (GND).

[0022] The base plate 50 is a circular plate (e.g., a circular plate with the same diameter as or larger than the ceramic plate 20 and a thickness of 25 mm) with good electrical and thermal conductivity and is electrically independent of the electrostatic electrode 22 and the heater electrode 30. A refrigerant flow path 52 through which a refrigerant circulates is provided within the base plate 50. The refrigerant flowing through the refrigerant flow path 52 is preferably a liquid, and is preferably electrically insulating. Examples of electrically insulating liquids include a fluorine-based inert liquid. As shown in FIG. 1 , the refrigerant flow path 52 is formed in a spiral shape in a plan view across the entire base plate 50 from one end (inlet 52 in) to the other end (outlet 52 out) in a single stroke. The inlet 52 in and outlet 52 out of the refrigerant flow path 52 are connected to a supply port and a recovery port of an external refrigerant device (not shown), respectively. The coolant supplied from the supply port of the external coolant device to the inlet 52in of the coolant flow path 52 passes through the coolant flow path 52, returns from the outlet 52out of the coolant flow path 52 to the recovery port of the external coolant device, and is then temperature-adjusted before being supplied again from the supply port to the inlet 52in of the coolant flow path 52. The base plate 50 is connected to a source power supply 72 and a bias power supply 74. The source power supply 72 generates a source RF power for generating plasma above the wafer mounting surface 21. The bias power supply 74 generates a bias RF power for attracting ions to the wafer W. The bias RF power has a lower frequency and a larger amplitude than the source RF power. The bias RF power may be a sine wave (alternating positive and negative signs) or a square wave (periodically appearing negative square signs), but a square wave is preferred for sharp etching. The frequency of the source RF power is, for example, several tens to several hundreds of megahertz, and the frequency of the bias RF power is, for example, several hundred kilohertz.

[0023] Examples of materials for the base plate 50 include metal materials and metal-ceramic composite materials. Metal materials include Al, Ti, Mo, and alloys thereof. Metal-ceramic composite materials include metal matrix composites (MMCs) and ceramic matrix composites (CMCs). Specific examples of such composite materials include materials containing Si, SiC, and Ti (also known as SiSiCTi), porous SiC materials impregnated with Al and / or Si, and composite materials of Al2O3 and TiC. It is preferable to select a material for the base plate 50 that has a thermal expansion coefficient close to that of the material for the ceramic plate 20.

[0024] The bonding layer 60 is a metal bonding layer that bonds the lower surface of the ceramic plate 20 to the upper surface of the base plate 50. The metal bonding layer may be, for example, a layer formed of solder or a metal brazing material. The metal bonding layer is formed, for example, by thermal compression bonding (TCB). TCB refers to a known method in which a metal bonding material is sandwiched between two components to be joined and the two components are pressure-bonded while heated to a temperature below the solidus temperature of the metal bonding material. The bonding layer 60 may also be a resin adhesive layer. Examples of materials for the resin adhesive layer include insulating resins such as epoxy resin, acrylic resin, and silicone resin, as well as insulating resins containing fillers.

[0025] As shown in FIG. 2 , the power supply member placement hole 54 is a generally cylindrical hole that vertically penetrates the base plate 50 and the bonding layer 60 without penetrating the coolant flow path 52. An insulating tube 56 is housed in the power supply member placement hole 54. The insulating tube 56 is fixed to the power supply member placement hole 54 with adhesive. An electrode terminal 26 electrically connected to the electrostatic electrode 22 is exposed at the top of the power supply member placement hole 54. A power supply member 58 is electrically connected to the electrode terminal 26. The power supply member 58 has an upper metal terminal 58a and a lower metal terminal 58b connected by a flexible metal wire 58c, and the upper metal terminal 58a is joined to the electrode terminal 26. The lower metal terminal 58b is exposed from the lower opening of the insulating tube 56 and is connected to a DC power source 70 for electrostatic chucking. The power supply member 58 may be a metal rod.

[0026] As shown in FIG. 2 , the gas passage 24 is a substantially cylindrical hole that vertically penetrates the base plate 50, the bonding layer 60, and the ceramic plate 20, but does not penetrate the coolant flow path 52. The gas passage 24 is connected to a He gas supply source 76. The gas passage 24 is provided so as to extend from the underside of the base plate 50 to the wafer mounting surface 21. An insulating tube 57 is housed in the portion of the gas passage 24 that penetrates the base plate 50 and the bonding layer 60. The insulating tube 57 is fixed to the gas passage 24 with adhesive. As shown in FIG. 3 , the gas passage 24 vertically penetrates the electrostatic electrode 22 and the heater electrode 30. Through holes 22 a, 30 a with diameters larger than the diameter of the gas passage 24 are provided in the portion of the electrostatic electrode 22 through which the gas passage 24 passes and in the portion of the heater electrode 30 through which the gas passage 24 passes. Therefore, as shown in FIGS. 4 and 5 , the electrostatic electrode 22 and the heater electrode 30 are not exposed to the inner wall of the gas passage 24.

[0027] Next, a brief description will be given of a manufacturing method for the ceramic plate 20 of the wafer mounting table 10. The ceramic plate 20 can be obtained by, for example, preparing three molded sheets, processing each molded sheet, stacking them, hot-press firing, and then performing shaping (such as drilling holes). For example, the first molded sheet from the top is used as is without processing. For the second molded sheet from the top, a conductive paste is printed on the top surface so that it has the same shape as the electrostatic electrode 22. For the third molded sheet from the top, a conductive paste is printed on the top surface so that it has the same shape as the heater electrode 30. Each molded sheet can be produced by tape casting or mold casting. These three sheets are then stacked and hot-press fired, and then shaping (such as drilling holes) is performed. The gas passages 24 may be formed before or after the hot-press firing.

[0028] Next, an example of how the wafer mounting table 10 configured as described above is described. First, the wafer mounting table 10 is installed in a chamber (not shown), and a wafer W is placed on the wafer mounting surface 21. The chamber is then depressurized using a vacuum pump to a predetermined vacuum level, and a DC voltage is applied to the electrostatic electrode 22 of the ceramic plate 20 to generate an electrostatic attraction force, thereby attracting and fixing the wafer W to the wafer mounting surface 21. He gas is then supplied to the gas passage 24 from a He gas supply source 76. The He gas fills the space surrounded by the seal band 21a, the small circular protrusions 21b, and the wafer W. This improves thermal conduction between the wafer W and the wafer mounting surface 21. Next, a reactive gas atmosphere at a predetermined pressure (e.g., several tens to several hundreds of Pa) is created in the chamber, and in this state, a source voltage from a source power supply 72 and a bias voltage from a bias power supply 74 are applied to the base plate 50. As a result, plasma is generated between an upper electrode (not shown) provided on the ceiling of the chamber and the wafer mounting surface 21 of the wafer mounting table 10. The surface of the wafer W is processed by the generated plasma. This processing may be, for example, a high-power plasma etching process such as deep etching. The temperature of the wafer W during plasma processing may be, for example, 50°C to 90°C. A coolant is circulated through the coolant flow path 52 of the base plate 50 as needed. The set temperature of the coolant may be, for example, -70°C to -30°C. In deep etching, a lower temperature allows etching to be performed more smoothly and the etching rate to be increased.

[0029] During application of the bias voltage, a potential gradient from positive to negative in the vertical direction is generated in the internal space of the gas passage 24 due to application of a DC voltage to the electrostatic electrode 22 and application of a bias voltage to the base plate 50, which serves as a bias electrode. In this embodiment, during application of the bias voltage, the heater electrode 30 provided inside the ceramic plate 20 is electrically connected to the electrostatic electrode 22 to set the heater electrode 30 at the same potential as the electrostatic electrode 22, thereby preventing a potential gradient from being generated in the vertical direction between the electrostatic electrode 22 and the heater electrode 30 in the internal space of the gas passage 24. At this time, a potential gradient from positive to negative is generated between the heater electrode 30 and the base plate 50, which serves as a bias electrode, but the vertical length over which the potential gradient is generated is short, being approximately the same as the distance between the heater electrode 30 and the base plate 50. Therefore, if the heater electrode 30 is kept at the same potential as the electrostatic electrode 22 while the bias voltage is being applied, even if the electrons generated as a result of the ionization of He atoms in the internal space of the gas passage 24 accelerate and hit other He atoms, the electrons will not acquire high energy because the acceleration distance is short, and therefore abnormal discharge will not occur even if they hit other He atoms.

[0030] In contrast, if the heater electrode 30 provided inside the ceramic plate 20 cannot be electrically connected to the electrostatic electrode 22 while the bias voltage is being applied, the vertical length over which a potential gradient occurs in the internal space of the gas passage 24 is longer than in this embodiment. Therefore, if electrons generated as a result of the ionization of He atoms in the internal space of the gas passage 24 accelerate and collide with other He atoms, the electrons will have high energy due to the long acceleration distance, and these electrons will collide with other He atoms, ionizing the He atoms and generating more electrons. This phenomenon is likely to occur repeatedly, making it more likely that abnormal discharge will occur.

[0031] Even if a DC voltage is applied to the electrostatic electrode 22, the potential gradient in the internal space of the gas passage 24 is small when a bias voltage is not applied to the bias electrode. In this state, electrons are not accelerated significantly, making it difficult for abnormal discharge to occur. Therefore, in this case, there is no need to connect the heater electrode 30 to the electrostatic electrode 22. On the other hand, when plasma is not generated (and typically, when no bias voltage is applied), the wafer W cools too much due to the lack of heat input from the plasma, which can result in cracking of the wafer W during subsequent transfer. In this embodiment, when plasma is not generated, the heater electrode 30 can be connected to the heater power supply 80 as needed to generate heat, thereby maintaining or raising the temperature of the wafer W to a desired temperature. While the heater electrode 30 is connected to the heater power supply 80, the external coolant device may be stopped to stop the circulation of the low-temperature coolant. While it is possible to maintain or raise the temperature of the wafer W to a desired temperature by switching the temperature of the coolant circulating through the coolant passage 52 to a high temperature, using the heater electrode 30 is preferable because it allows the wafer W to reach the desired temperature in a short time.

[0032] The connection destination of the heater electrode 30 may be switched by an operator operating the switching unit 35, or a control unit (not shown) connected to the switching unit 35 may control the switching unit 35. The control unit is configured as a microprocessor including a CPU, a storage unit, etc. The control unit may also be connected to the DC power supply 70 and the bias power supply 74, and may control the switching unit 35 so that the heater electrode 30 is electrically connected to the electrostatic electrode 22 while a DC voltage is being applied to the electrostatic electrode 22 and a bias voltage is being applied to the bias electrode 22.

[0033] In the wafer mounting table 10 described above, the heater electrode 30 is located below the electrostatic electrode 22 and is disposed inside the ceramic plate 20 so as to surround the gas passage 24 and not be exposed to the inner wall of the gas passage 24. A switching unit 35 is connected to the heater electrode 30, which switches between electrically connecting and disconnecting the heater electrode 30 from the electrostatic electrode 22. The electrostatic electrode 22 has a positive potential when a DC voltage is applied to attract the wafer W onto the wafer mounting surface 21. The base plate 50, which serves as a bias electrode, periodically has a negative potential when a bias voltage is applied to attract ions in the plasma. Therefore, while the bias voltage is being applied, a potential gradient from positive to negative is generated vertically within the interior space of the gas passage 24. If a thermally conductive gas such as He gas is present in the gas passage 24, electrons ionized from He atoms are accelerated by the electric field and collide with other unionized He atoms, ultimately resulting in an arc discharge. In this embodiment, the heater electrode 30 provided below the electrostatic electrode 22 is electrically connected to the electrostatic electrode 22 to set the heater electrode 30 at the same potential as the electrostatic electrode 22, thereby shortening the vertical distance over which the potential gradient occurs. As a result, even if electrons are generated by ionization of He atoms, they are not sufficiently accelerated by the potential gradient and do not have sufficient energy, thereby preventing arc discharge. This makes it possible to prevent or reduce the occurrence of abnormal discharge in the gas passage 24. Furthermore, when it is not necessary to set the heater electrode 30 at the same potential as the electrostatic electrode 22, such as when a bias voltage is not being applied, the heater electrode 30 can be electrically disconnected from the electrostatic electrode 22.

[0034] The switching unit 35 is configured to be able to switch between electrically connecting the heater electrode 30 to the electrostatic electrode 22 and connecting it to the heater power supply 80. When no bias voltage or source voltage is applied, there is no risk of abnormal discharge occurring, but the wafer may become too cold. However, by connecting the heater electrode 30 to the heater power supply 80 and causing it to generate heat, the wafer W can be maintained at or heated to a desired temperature.

[0035] Furthermore, the heater electrode 30 branches and merges around the periphery of the gas passage 24 so as to surround the gas passage 24. In this way, the heater electrode 30 surrounds the entire periphery of the gas passage 24 without interruption, and therefore, when the heater electrode 30 is electrically connected to the electrostatic electrode 22, it is possible to suppress variations in the potential distribution in the circumferential direction of the gas passage 24.

[0036] Furthermore, the base plate 50 also serves as a bias electrode, so there is no need to provide a bias electrode separate from the base plate 50.

[0037] The gas passage 24 is connected to a He gas supply source 76. Therefore, in the internal space of the gas passage 24, He atoms are ionized to generate electrons, and these electrons are likely to collide with other He atoms, making the application of the present invention highly significant.

[0038] Furthermore, the base plate 50 also serves as a source electrode, so there is no need to provide a source electrode separately from the base plate 50.

[0039] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0040] In the above-described embodiment, the base plate 50 also serves as the bias electrode, but the bias electrode may be built into the ceramic plate 20 .

[0041] For example, FIG. 6 shows an example in which a bias electrode 40 is provided below the heater electrode 30 of the above-described embodiment as an example in which a bias electrode is built into the ceramic plate 20. In FIG. 6, the same components as those in the above-described embodiment are denoted by the same reference numerals. The bias electrode 40 is a mesh planar electrode having substantially the same shape as the electrostatic electrode 22. The bias electrode 40 is not electrically connected to either the electrostatic electrode 22 or the heater electrode 30, but is connected to a bias power supply 74. A through-hole 40a having a diameter larger than that of the gas passage 24 is provided in the bias electrode 40 at a portion through which the gas passage 24 passes. Therefore, the bias electrode 40 is not exposed to the inner wall of the gas passage 24. The example in FIG. 6 also achieves the same effects as the above-described embodiment. Note that when the bias RF generated by the bias power supply 74 is a rectangular wave, it is preferable to make the bias electrode independent from the source electrode in order to protect the source power supply 72. Therefore, when the bias RF is a rectangular wave, it is preferable to build the bias electrode 40 into the ceramic plate 20 rather than using the base plate 50, which also serves as the source electrode, as the bias electrode. In the case of FIG. 6, the bias electrode can be brought closer to the wafer placement surface 21, so that the time constant of the transient response can be shortened.

[0042] When the bias electrode is built into the ceramic plate 20, an outer bias electrode electrically independent from the bias electrode may be provided on the outer periphery of the bias electrode 40. Although not shown, the outer bias electrode is a ring-shaped electrode provided on the same plane as the circular bias electrode 40 and is not electrically connected to the electrostatic electrode 22, the heater electrode 30, or the bias electrode 40. This allows different bias voltages to be applied to the bias electrode 40 and the outer bias electrode. This allows the degree of ion attraction to be different between the central and peripheral sides of the wafer W. Note that if a focus ring is placed on a step provided along the outer periphery of the ceramic plate 20, the degree of ion attraction between the focus ring and the wafer W can also be changed.

[0043] In the above-described embodiment, the switching unit 35 is configured to be able to switch between electrically connecting the heater electrode 30 to the electrostatic electrode 22 and connecting it to the heater power supply 80, but this is not limiting. For example, the switching unit 35 may be configured to be able to switch between electrically connecting the heater electrode 30 to the electrostatic electrode 22, connecting it to the heater power supply 80, or keeping it in an off state without being connected to various power sources. Also, for example, the switching unit 35 may be configured to be able to switch between electrically connecting the heater electrode 30 to the electrostatic electrode 22 and keeping it in an off state without being connected to various power sources. In this way, by appropriately turning off the heater electrode 30, power consumption can be reduced.

[0044] In the above-described embodiment, the heater electrode 30 is provided as the internal electrode, but this is not limiting. For example, the internal electrode may not function as a heater electrode (i.e., it may not be connected to the heater power supply 80) and may only function as a potential gradient adjusting electrode, or may have other functions.

[0045] In the above-described embodiment, the heater electrode 30 has the parallel portion 32, but it does not have to have the parallel portion 32 as long as it is located around the gas passage 24 and is not exposed to the inner wall of the gas passage 24.

[0046] In the above-described embodiment, the heater electrodes 30 are wired so as to cover almost the entire area of ​​the ceramic plate 20, from one 31a of the pair of terminals 31 to the other 31b. However, this is not limiting. For example, the ceramic plate 20 may be divided into a plurality of small zones, and the heater electrodes 30 may be wired in each small zone. In this case, each heater electrode 30 is wired so as to start from one 31a of the pair of terminals 31, cover almost the entire area of ​​the small zone, and then reach the other 31b of the pair of terminals 31. The small zones may be, for example, circular or annular zones divided by boundaries concentric with the ceramic plate 20, or fan-shaped zones divided by lines extending radially from the center of the ceramic plate 20. Note that when a plurality of heater electrodes 30 are provided, individual or common switching units 35 may be connected to all of the heater electrodes 30, or individual or common switching units 35 may be connected only to the heater electrodes 30 arranged around the gas passage 24.

[0047] In the above-described embodiment, one layer of heater electrodes 30 is provided. However, two or more layers of heater electrodes 30 may be provided. In this case, the switching unit 35 may be connected to at least one heater electrode 30, but it is preferable to connect the switching unit 35 to at least the lowest heater electrode 30. Connecting the switching unit 35 to the lowest heater electrode 30 can shorten the vertical distance over which a potential gradient occurs. Furthermore, connecting the switching unit 35 to all heater electrodes 30 improves the potential distribution in the gas passage 24. When two or more layers of heater electrodes 30 are provided, the switching unit 35 may be directly connected to each heater electrode 30. Alternatively, two or more layers of heater electrodes 30 may be connected by vias extending in the vertical direction, with the switching unit 35 directly connected to one of the heater electrodes 30 and the switching unit 35 indirectly connected to the other heater electrodes 30 via vias. Note that some of the internal electrodes in two or more layers may be heater electrodes 30 and the remaining may be electrodes other than heater electrodes 30, or all of the internal electrodes in two or more layers may be electrodes other than heater electrodes 30.

[0048] In the above-described embodiment, a porous plug (a plug that allows gas to flow in the vertical direction) may be provided in a portion of the gas passage 24 where a potential distribution occurs. Furthermore, instead of a porous plug, a dense plug having a zigzag or spiral passage (a passage that allows gas to flow in the vertical direction) may be used. This makes it easier to prevent abnormal discharge from occurring in the portion where a potential distribution occurs.

[0049] In the above-described embodiment, three gas passages 24 are provided, but the number of gas passages 24 is not particularly limited thereto and may be any number. Furthermore, although the gas passages 24 are described as passages that vertically penetrate the wafer mounting table 10, the number of gas passages 24 is not particularly limited thereto. For example, a gas channel structure may be employed instead of the gas passages 24. The gas channel structure may include a ring-shaped passage provided inside the base plate 50 and concentric with the base plate 50 in a plan view, a gas introduction passage that introduces gas from the underside of the base plate 50 into the ring-shaped passage, and multiple gas distribution passages that extend upward from the ring-shaped passage and open to the wafer mounting surface 21. The number of gas introduction passages may be fewer than the number of gas distribution passages, for example, one. Such a gas channel structure also corresponds to the "passage" of the present invention.

[0050] In the above-described embodiment, lift pin holes may be provided separately from the gas passages 24. The lift pin holes are holes that penetrate the wafer mounting table 10 in the vertical direction and allow the insertion of lift pins that move the wafer W up and down relative to the wafer mounting surface 21. When the wafer W is supported by, for example, three lift pins, three lift pin holes are provided. The configuration of the lift pin holes and their surroundings is similar to the configuration of the gas passages 24 and their surroundings. The lift pin holes are provided so as to extend from the underside of the ceramic plate 20 to the wafer mounting surface 21. Therefore, He gas also enters the lift pin holes, but, like the gas passages 24, the occurrence of abnormal discharge in the lift pin holes can be prevented or reduced. Such lift pin holes also correspond to the "passages" of the present invention.

[0051] The semiconductor manufacturing equipment member of the present invention can be used, for example, in the field of processing wafers with plasma or the like.

[0052] 10 wafer mounting table, 20 ceramic plate, 21 wafer mounting surface, 21a seal band, 21b small circular protrusion, 22 electrostatic electrode, 22a through hole, 24 gas passage, 26 electrode terminal, 30 heater electrode, 30a through hole, 31 pair of terminals, 31a one side, 31b other side, 32 parallel portion, 32a branch point, 32b junction point, 35 switching portion, 40 bias electrode, 40a through hole, 50 base plate, 52 coolant flow path, 52in inlet, 52out outlet, 54 power supply member arrangement hole, 56, 57 insulating tube, 58 power supply member, 58a upper metal terminal, 58b lower metal terminal, 58c metal wire, 60 bonding layer, 70 DC power supply, 72 source power supply, 74 bias power supply, 76 He gas supply source, 80 Heater power supply.

Claims

1. A component for semiconductor manufacturing equipment comprising: a ceramic plate having a wafer mounting surface on its upper surface and incorporating an electrostatic electrode; a base plate provided on the underside of the ceramic plate and incorporating a coolant flow path; a passage provided from the underside of the base plate to the wafer mounting surface of the ceramic plate; an internal electrode provided inside the ceramic plate so as to be located below the electrostatic electrode and around the passage and not exposed to the inner wall of the passage; a switching unit connected to the internal electrode and configured to be able to switch whether the internal electrode is electrically connected to the electrostatic electrode; and a bias electrode provided at the same height as the internal electrode or lower and electrically independent of the electrostatic electrode, to which a bias voltage is applied when plasma is generated above the wafer mounting surface.

2. A component for semiconductor manufacturing equipment as described in claim 1, wherein the internal electrode is a heater electrode that is connected to a heater power source and generates heat, and the switching unit is configured to be able to switch between electrically connecting the heater electrode to the electrostatic electrode or connecting the heater electrode to the heater power source.

3. A semiconductor manufacturing equipment member according to claim 2, wherein the heater electrode is wired so as to extend from one of a pair of terminals to the other of the pair of terminals, and is positioned around the passage, branching and merging around the passage.

4. The semiconductor manufacturing equipment member according to claim 3, wherein the heater electrodes form a parallel circuit around the passage.

5. A semiconductor manufacturing equipment member according to any one of claims 1 to 4, wherein the base plate also serves as the bias electrode.

6. The semiconductor manufacturing equipment member according to any one of claims 1 to 4, wherein the bias electrode is built into the ceramic plate.

7. The semiconductor manufacturing equipment member according to any one of claims 1 to 4, wherein the passage is connected to a source of heat transfer gas.

8. A semiconductor manufacturing equipment member according to any one of claims 1 to 4, wherein the base plate also serves as a source electrode to which a source voltage is applied when generating plasma above the wafer mounting surface.

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