JP7808399B2 - Substrate support, substrate processing apparatus and method for manufacturing substrate support - Google Patents

Description

The present disclosure relates to a substrate support, a substrate processing apparatus, and a method for manufacturing a substrate support.

Patent Document 1 discloses a substrate processing apparatus that includes a base having a coolant flow path therein that extends to an inlet and an outlet, and a mounting table that has an electrostatic chuck attached to the top surface of the base via adhesive and has a heater attached to the inside or bottom surface of the electrostatic chuck.

JP 2013-172013 A

The technology disclosed herein provides a substrate support that can appropriately adjust the temperature of the substrate using a heat transfer medium that flows through a flow path formed in the base.

One aspect of the present disclosure is a substrate support for supporting a substrate, the substrate support comprising: a substrate support portion made of a first material configured to support the substrate; a base made of a second material different from the first material and having a flow path configured to allow a temperature control fluid to flow through the base; and a diffusion bonding portion formed in a boundary region between the substrate support portion and the base, wherein the difference between the linear expansion coefficients of the first material and the second material is 1.0 × 10 ^-6 /°C or less.

This disclosure provides a substrate support that can appropriately adjust the substrate temperature using a heat transfer fluid that flows through a flow path formed in the base.

FIG. 1 is a vertical cross-sectional view showing an example of the configuration of a plasma processing system according to this embodiment. FIG. 2 is a vertical cross-sectional view showing an example of the configuration of a substrate support according to this embodiment. FIG. 3 is a schematic cross-sectional view showing an example of the configuration of a conventional substrate support. FIG. 4 is a vertical cross-sectional view showing an example of the configuration of a substrate support according to a first modified example of the present embodiment. FIG. 5 is a plan view showing an example of the configuration of a substrate support according to a first modified example of the present embodiment. FIG. 6 is a vertical cross-sectional view showing an example of the configuration of a substrate support according to a second modification of this embodiment. FIG. 7 is a flowchart of substrate processing using a substrate processing apparatus including a substrate support according to Modification 2 of this embodiment.

In the manufacturing process of semiconductor devices, an etching process is performed on a layer to be etched (e.g., a silicon-containing film) formed by stacking on the surface of a semiconductor substrate (hereinafter simply referred to as "substrate"), using a pre-patterned mask layer (e.g., a resist film) as a mask. This etching process is generally performed in a plasma processing apparatus equipped with a substrate support that uses electrostatic force to attract and hold the substrate.

Patent Document 1 discloses a substrate processing apparatus equipped with such a substrate support (mounting table). The substrate support described in Patent Document 1 is formed by bonding, via adhesive, a base in which a flow path for a coolant is formed and an electrostatic chuck equipped with a heater for heating the substrate.

In recent plasma processing equipment, the aforementioned etching process may involve a 3D NAND HARC (High Aspect Ratio Contact) process (hereinafter simply referred to as the "HARC process"), in which holes are dug deep into a stacked substrate. However, while the HARC process requires high RF (Radio Frequency) power to properly dig deep holes, the high RF power can cause the substrate to heat up, potentially making it impossible to properly form holes. Specifically, the high substrate temperature can clog the opening of holes formed on the substrate, potentially making it impossible to properly dig deep holes.

Here, one possible method for preventing hole clogging and properly performing the HARC process is to keep the substrate being processed at a temperature below the desired temperature, i.e., to properly cool the substrate.

As disclosed in Patent Document 1, a substrate supported by a substrate support is typically cooled by a coolant flowing through a flow path formed inside the base of the substrate support. However, when the base with the flow path formed and the electrostatic chuck supporting the substrate are joined using an adhesive containing a resin material (hereinafter referred to as a "resin adhesive"), as in the substrate support (mounting table) disclosed in Patent Document 1, the substrate may not be cooled properly. This is because the thermal resistance of the resin adhesive is greater than the thermal resistance of the electrostatic chuck and base, and the resin adhesive inhibits heat transfer from the coolant to the substrate. Therefore, from this perspective, there is room for improvement in conventional substrate supports, and there is a need to develop a substrate support that can achieve both higher RF power and lower substrate temperatures.

The technology disclosed herein has been developed in light of the above circumstances, and provides a substrate support that can appropriately cool a substrate using a heat transfer fluid flowing through a flow path formed in a base. Below, a plasma processing system serving as a substrate processing apparatus according to this embodiment will be described with reference to the drawings. Note that in this specification and drawings, elements that have substantially the same functional configuration are designated by the same reference numerals, and redundant description will be omitted.

<Plasma treatment device>
First, a plasma processing system according to the present embodiment will be described with reference to Fig. 1, which is a longitudinal sectional view showing the outline of the configuration of the plasma processing system according to the present embodiment.

The plasma processing system includes a capacitively coupled plasma processing device 1 and a control unit 2. The plasma processing device 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing device 1 also includes a substrate support 11 and a gas inlet unit. The substrate support 11 is disposed within the plasma processing chamber 10. The gas inlet unit is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet unit includes a showerhead 13. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. Within the plasma processing chamber 10, a plasma processing space 10s is formed, defined by the showerhead 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas supply port 13a for supplying at least one processing gas to the plasma processing space 10s and at least one gas exhaust port 10e for exhausting gas from the plasma processing space 10s. The sidewall 10a is grounded. The showerhead 13 and substrate support 11 are electrically insulated from the plasma processing chamber 10.

The substrate support 11 includes a body member 111 and a ring assembly 112. The upper surface of the body member 111 has a central region 111a (substrate support surface) for supporting the substrate (wafer) W, and an annular region 111b (ring support surface) for supporting the ring assembly 112. The annular region 111b surrounds the central region 111a in a plan view. The ring assembly 112 includes one or more annular members, at least one of which is an edge ring.

As shown in FIG. 2, in one embodiment, the main body member 111 includes a base 113 and an electrostatic chuck 114. The electrostatic chuck 114 is an example of a substrate support portion that supports a substrate. The base 113 and the electrostatic chuck 114 are diffusion bonded. When the base 113 and the electrostatic chuck 114 are diffusion bonded, a diffusion bonded portion 115 is formed in the boundary region between the base 113 and the electrostatic chuck 114.

The base 113 is made of a conductive material such as titanium (Ti), as described below. The base 113 functions as a lower electrode. The base 113 has a flow path C, through which a heat transfer medium (temperature-controlling fluid) is circulated and supplied from a chiller unit (not shown). By circulating the heat transfer medium through flow path C, the ring assembly 112, the electrostatic chuck 114 (described below), and the substrate W are adjusted to the desired temperature. As an example of the heat transfer medium, a refrigerant such as cooling water can be used.

In FIG. 2, flow path C is formed below the central region 111a (substrate W) of the base 113, but flow path C may also be formed below the annular region 111b corresponding to the ring assembly 112.

The electrostatic chuck 114 is diffusion-bonded to the upper surface of the base 113. The upper surface of the electrostatic chuck 114 has the aforementioned central region 111a and annular region 111b. Inside the electrostatic chuck 114, there is provided a first electrode 114a for attracting and holding the substrate W, and a second electrode 114b for attracting and holding the ring assembly 112. The electrostatic chuck 114 is configured by sandwiching the first electrode 114a and second electrode 114b between a pair of dielectric films made of a dielectric material such as ceramics.

Note that Figure 2 illustrates an example in which the central region 111a of the electrostatic chuck 114, which holds the substrate W on its upper surface, and the annular region 111b of the electrostatic chuck 114, which holds the ring assembly 112 on its upper surface, are integrally configured. However, the configuration of the electrostatic chuck 114 is not limited to this, and the central region 111a and the annular region 111b of the electrostatic chuck 114 may be configured independently. By configuring the central region 111a and the annular region 111b independently in this manner, the temperature adjustment of the substrate W and the temperature adjustment of the ring assembly 112 can be thermally separated and performed independently.

Although not shown, the substrate support 11 may further include a heating module such as a heater that heats at least one of the ring assembly 112, the electrostatic chuck 114, and the substrate W. The heater as a heating module may be provided, for example, inside the electrostatic chuck 114, below the first electrode 114a and/or the second electrode 114b. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas (backside gas) between the back surface of the substrate W and the upper surface of the electrostatic chuck 114.

The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied from the gas supply unit 20 to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes a conductive member. The conductive member of the shower head 13 functions as an upper electrode. In addition to the shower head 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include one or more flow modulation devices that modulate or pulse the flow rate of the at least one process gas.

The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to the conductive member (lower electrode) of the substrate support 11 and/or the conductive member (upper electrode) of the showerhead 13. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more processing gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the lower electrode, a bias potential is generated on the substrate W, which can attract ion components in the formed plasma to the substrate W.

In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to the lower electrode and/or the upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to the lower electrode and/or the upper electrode. The second RF generating unit 31b is coupled to the lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generating unit 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to the lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the lower electrode. In one embodiment, the first DC signal may be applied to another electrode, such as an attraction electrode in the electrostatic chuck 114. In one embodiment, the second DC generator 32b is connected to the upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the upper electrode. In various embodiments, at least one of the first and second DC signals may be pulsed. Note that the first and second DC generators 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generator 32a may be provided instead of the second RF generator 31b.

The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the internal pressure of the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various steps described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various steps described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a memory unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on programs stored in the memory unit 2a2. The memory unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

Various exemplary embodiments have been described above, but the present invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

<Substrate Processing Method Using Plasma Processing Apparatus>
Next, a description will be given of an example of a method for processing the substrate W in the plasma processing apparatus 1 configured as above. In the plasma processing apparatus 1, the substrate W is subjected to an etching process (for example, a HARC process).

First, a substrate W is loaded into the plasma processing chamber 10 and placed on the electrostatic chuck 114 of the substrate support 11. Next, a voltage is applied to the attraction electrode of the electrostatic chuck 114, causing the substrate W to be attracted and held to the electrostatic chuck 114 by electrostatic force.

Once the substrate W is attracted and held by the electrostatic chuck 114, the interior of the plasma processing chamber 10 is then depressurized to a predetermined vacuum level. Next, processing gas is supplied from the gas supply unit 20 to the plasma processing space 10s via the shower head 13. Furthermore, source RF power for plasma generation is supplied from the first RF generator 31a to the lower electrode, thereby exciting the processing gas and generating plasma. At this time, bias RF power may also be supplied from the second RF generator 31b. Then, in the plasma processing space 10s, the substrate W is etched by the action of the generated plasma.

When the etching process is terminated, the supply of source RF power from the first RF generation unit 31a and the supply of process gas from the gas supply unit 20 are stopped. If bias RF power was being supplied during the etching process, the supply of that bias RF power is also stopped.

Next, the electrostatic chuck 114 stops attracting and holding the substrate W, and the electrostatic chuck 114 is de-electrified after the etching process. The substrate W is then detached from the electrostatic chuck 114 and removed from the plasma processing apparatus 1. This completes the etching process.

<Method for cooling a substrate supported by a substrate support>
3 is a schematic cross-sectional view showing an example of the configuration of a conventional substrate support 200 provided in a substrate processing apparatus such as that disclosed in Patent Document 1. In the following description, elements having the same configuration as the substrate support 11 according to the technique of the present disclosure are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 3, a conventional substrate support 200 includes an electrostatic chuck 114 and a base 201. The electrostatic chuck 114 and the base 201 are laminated and bonded together via an adhesive 202.

The electrostatic chuck 114 has a configuration similar to that of the electrostatic chuck 114 used in the substrate support 11. That is, it is configured by sandwiching an attraction electrode between insulating materials such as ceramics. The substrate W and ring assembly 112 are attracted and held on the upper surface of the electrostatic chuck 114.

The base 201 is made of a conductive material such as an aluminum alloy. The base 201 functions as a lower electrode. A flow path C is formed in the base 201.

The adhesive 202 bonds the electrostatic chuck 114 and the base 201. As mentioned above, the adhesive 202 generally has a higher thermal resistance (lower thermal conductivity) than the electrostatic chuck 114 and the base 201. For this reason, if a substrate W is supported by a conventional substrate support 200 and an etching process (e.g., a HARC process) is performed, there is a risk that holes may not be dug deep enough in the substrate W appropriately. That is, as mentioned above, when high-power RF is applied to the lower electrode, the substrate W attracted and held by the electrostatic chuck 114 becomes hot, which may block the opening of the hole and prevent etching from proceeding.

One method for preventing the opening of the hole from becoming blocked is to cool the substrate W held by the electrostatic chuck 114 by heat transfer from the coolant flowing through the flow path C formed in the base 201. However, as in conventional substrate support 200, if the base 201, in which the flow path C is formed, and the electrostatic chuck 114, which attracts and holds the substrate W, are joined with a resin adhesive with high thermal resistance (thermal conductivity: 0.2 to 0.3 W/mK), the resin adhesive may impede heat transfer from the coolant to the substrate W, preventing the substrate W from being cooled properly.

In the substrate support 11 according to this embodiment, as shown in FIG. 2, the base 113, on which the flow path C is formed, and the electrostatic chuck 114 are joined by diffusion bonding. This promotes heat transfer from the coolant flowing through the flow path C to the electrostatic chuck 114 (substrate W) compared to conventional methods, allowing the substrate W to be cooled appropriately. In other words, it is possible to achieve both higher RF power applied to the lower electrode and lower temperatures for the substrate W.

When the base 113 and the electrostatic chuck 114 are diffusion bonded as in this embodiment, the top surface of the base 113 and the bottom surface of the electrostatic chuck 114 are brought into contact with each other, and pressure is applied to these components in a high-temperature environment. If the difference in linear expansion coefficient between the base 113 and the electrostatic chuck 114 is large, residual stress caused by thermal stress generated during bonding may cause damage or warping of the base 113 or the electrostatic chuck 114.

For example, in the case of a conventional substrate support 200 shown in FIG. 3 , when a base 201 made of an aluminum alloy (linear expansion coefficient: approximately 23×10 ⁻⁶ /°C) is diffusion-bonded to an electrostatic chuck 114 made of ceramics (linear expansion coefficient: approximately 7×10 ⁻⁶ to 8×10 ⁻⁶ /°C), the amount of thermal expansion of the base 201 is greater than that of the electrostatic chuck 114, and residual stresses that arise when the base 201 is cooled to room temperature can cause damage or warping of the base 113 and the electrostatic chuck 114.

Therefore, in this embodiment, the difference in linear expansion coefficient between the first material constituting the electrostatic chuck 114 and the second material constituting the base is set to 1.0×10 ⁻⁶ /°C or less. For example, ceramics such as alumina containing SiC (linear expansion coefficient: approximately 7.8×10 ⁻⁶ /°C) are used as the first material, and titanium or a titanium alloy (linear expansion coefficient: approximately 8.4×10 ⁻⁶ /°C) are used as the second material. In this way, by reducing the difference in linear expansion coefficient between the electrostatic chuck 114 and the base 113 joined by the diffusion bonding portion 115, it is possible to reduce the thermal stress generated when the electrostatic chuck 114 and the base 113 are joined. In other words, it is possible to reduce the residual stress generated between the electrostatic chuck 114 and the base 113, thereby appropriately suppressing damage and warping of the base 113 and the electrostatic chuck 114 due to the difference in linear expansion coefficient. Note that the above-mentioned linear expansion coefficient refers to the linear expansion coefficient at room temperature.

As described above, a diffusion bonded portion 115 is formed at the boundary between the base 113 and the electrostatic chuck 114. For example, when the base 113 and the electrostatic chuck 114 are diffusion bonded together with the top surface of the base 113 and the bottom surface of the electrostatic chuck 114 in contact with each other, the diffusion bonded portion 115 is composed of the first material and the second material. More specifically, grain boundary migration occurs at the boundary between the electrostatic chuck 114 and the base 113, resulting in a mixture of crystal grains of the first material and crystal grains of the second material. In this embodiment, the base 113 and the electrostatic chuck 114 may also be diffusion bonded via a third material different from the first and second materials. That is, the base 113 and the electrostatic chuck 114 may be diffusion bonded with a third material, such as an insert metal, that can diffuse into the first and second materials, sandwiched between the top surface of the base 113 and the bottom surface of the electrostatic chuck 114. In this case, the diffusion bonded portion 115 is composed of a first material, a second material, and a third material.

In the present embodiment, the second material constituting the base 113 is not limited to titanium or a titanium alloy as shown in the present embodiment, and can be any conductive material having a linear expansion coefficient difference of 1.0×10 ⁻⁶ /°C or less from that of the electrostatic chuck 114. Specifically, the inventors have conducted extensive studies and found that if the linear expansion coefficient of the second material constituting the base 113 is about 7 to 9×10 ⁻⁶ /°C, damage or warping of the base 113 or the electrostatic chuck 114 due to the difference in linear expansion coefficient can be appropriately suppressed. Examples of other conductive materials having a linear expansion coefficient difference of 1.0×10 ⁻⁶ /°C or less from that of ceramics include, for example, low-thermal expansion iron-nickel alloys.

Here, the substrate support 11 of this embodiment can be manufactured, for example, by pressing the bottom surface of the electrostatic chuck 114 and the top surface of the base 113 in a state where these components are in contact with each other in a high-temperature environment. Examples of a method for pressing in a high-temperature environment include hot pressing. In this case, even if the difference in linear expansion coefficient between the first material constituting the electrostatic chuck 114 and the second material constituting the base 113 is 1.0×10 ⁻⁶ /°C or less, as described above, there is a risk that the electrostatic chuck 114 and the base 113 may be damaged due to thermal stress generated during bonding. Generally, since the linear expansion coefficient is temperature-dependent, if materials whose linear expansion coefficients differ greatly in the temperature range where diffusion bonding is performed are used as the first material and the second material, the electrostatic chuck 114 and the base 113 are likely to be damaged or warped.

In this embodiment, therefore, it is desirable to increase the pressure during diffusion bonding and lower the bonding temperature in order to prevent damage to the electrostatic chuck 114 and base 113 due to thermal stress generated during such bonding. Conventionally, diffusion bonding of titanium or titanium alloys is generally performed under conditions of 0.6 MPa to 2 MPa and 850°C to 930°C. In contrast, in this embodiment, it is desirable to perform the bonding under conditions of, for example, 2 MPa or higher and 500°C or lower. By performing diffusion bonding under these conditions, it is possible to reduce the difference in the amount of thermal expansion generated during bonding, thereby preventing damage or warping of the electrostatic chuck 114 and properly bonding the base 113 and electrostatic chuck 114.

<Modification 1>
As described above, in the substrate support 11 according to this embodiment, the difference in the linear expansion coefficient between the first material constituting the electrostatic chuck 114 and the second material constituting the base 113 is set to 1.0×10 ⁻⁶ /°C or less, thereby suppressing warping or damage to the electrostatic chuck 114 due to the difference in the linear expansion coefficient between the first material and the second material. However, if the residual stress generated during manufacturing cannot be sufficiently reduced, warping or damage may occur to the electrostatic chuck 114 or the base 113. Furthermore, in a process in which low-temperature processes and high-temperature processes are repeatedly performed on the substrate W, distortion may accumulate in the electrostatic chuck 114 or the base 113, which may similarly cause warping or damage to the electrostatic chuck 114 or the base 113.

In contrast, in Modification 1 shown in FIG. 4, multiple grooves 116 are formed in the bonding surface of the base 113 (the surface facing the back surface of the electrostatic chuck 114). FIG. 5 is a plan view of the base 113 of Modification 1. As shown in FIG. 5(a), the grooves 116 may be formed concentrically. In this case, each groove 116 may be divided into multiple segments in the circumferential direction. FIG. 5(b) shows an example in which the groove 116 is divided into four segments in the circumferential direction, and FIG. 5(c) shows an example in which the groove 116 is divided into eight segments in the circumferential direction. Alternatively, the groove 116 may be formed in a spiral shape. With this configuration, residual stress generated during manufacturing or substrate processing can be alleviated by deformation of the grooves 116. This makes it possible to further suppress warping and damage to the electrostatic chuck 114 or base 113.

<Modification 2>
The second modification of the substrate support 11 according to this embodiment, shown in FIG. 6, is the same as the first modification shown in FIG. 4, except that a heat transfer gas control system 117 is added to supply a heat transfer gas into the groove 116 and control the pressure of the heat transfer gas. The heat transfer gas may be an inert gas such as helium (He). The heat transfer gas control system 117 may include a heat transfer gas supply source 117a, a gas line 117b connecting the groove 116 to the heat transfer gas supply source 117a, a pressure control device 117c for controlling the pressure of the heat transfer gas supplied to the groove 116, a pump 117d for depressurizing the groove 116, and a recovery tank 117e for recovering the heat transfer gas supplied to the groove 116. The heat transfer gas control system 117 may also include valves V1 to V5 at various points on the gas line. This configuration allows the amount of heat transfer from the substrate W to the coolant during substrate processing to be changed by changing the pressure of the heat transfer gas in the groove 116. As a result, for example, in a process in which a high-temperature process and a low-temperature process are repeatedly performed on the substrate W, the time required for temperature change can be shortened, thereby improving productivity. In the modification of Fig. 6, a temperature sensor 118 may be provided to measure the temperature of the electrostatic chuck 114. A radiation thermometer or the like can be used as the temperature sensor 118.

Figure 7 shows an example of a substrate processing flow using the substrate support 11 according to Modification 2. Figure 7 shows an example of a flow when a substrate W is subjected to low-temperature etching (first etching) and high-temperature etching (second etching, third etching). Note that in the initial state, valves V1 to V5 are closed.

In ST1, valve V3 is opened and the pressure inside groove 116 is reduced by pump 117d. Pump 117d can be, for example, a dry pump. In ST2, valve V1 is opened and the pressure inside groove 116 is measured by pressure control device 117c. In ST3, valve V3 is closed and valve V2 is opened to supply heat transfer gas from heat transfer gas supply source 117a into groove 116 via gas line 117b. In ST4, once the pressure inside groove 116 reaches a predetermined pressure, valve V3 is closed and temperature sensor 118 measures the temperature of electrostatic chuck 114. In ST5, after the electrostatic chuck 114 reaches a predetermined temperature, the first etching is initiated. In one example, the pressure inside groove 116 during the first etching is set to 30 Torr. This promotes heat transfer from the substrate W to the coolant.

After the first etching is completed, in ST6, valve V1 is closed and valve V4 is opened to reduce the pressure inside the recovery tank 117e. In one example, the recovery tank 117e is reduced to a vacuum state. In ST7, valves V5 and V1 are opened to recover the heat transfer gas inside the groove 116 into the recovery tank 117e. In ST8, valve V5 is closed and valve V3 is opened, and the groove 116 is reduced in pressure using pump 117d. In ST9, after confirming that the groove 116 has reached a predetermined pressure using pressure control device 117c, the second etching begins. In one example, the pressure inside the groove 116 during the second etching is set to 0 to 10 Torr. This suppresses heat transfer from the substrate W to the coolant. Thereafter, ST1 to ST9 are repeated, and after a predetermined number of substrates W have been etched, the process is terminated.

In variant 2, by controlling the pressure of the heat transfer gas in the groove 116, the time required for the temperature of the substrate W to change during substrate processing can be shortened. Furthermore, the heat transfer gas can be recovered and reused, enabling cost improvements and resource conservation.

<Functions and Effects of the Substrate Support According to the Present Disclosure>
As described above, according to the substrate support 11 of this embodiment, the base 113 in which the flow path C is formed and the electrostatic chuck 114 that attracts and holds the substrate W are diffusion-bonded.

This allows heat to be transferred appropriately from the refrigerant to the substrate W, allowing the substrate W to be cooled appropriately. Therefore, even when a HARC process is performed, the substrate W can be cooled appropriately. In other words, the substrate support 11 of this embodiment can achieve both high RF power and low substrate W temperatures, allowing deep holes to be dug appropriately in the substrate W.

According to this embodiment, the difference in linear expansion coefficient between the first material constituting the electrostatic chuck 114 and the second material constituting the base 113 is set to 1.0×10 ⁻⁶ /°C or less. This makes it possible to suppress breakage or cracking of the electrostatic chuck 114 due to the difference in linear expansion coefficient between the base 113 and the electrostatic chuck 114 when the base 113 and the electrostatic chuck 114 are diffusion-bonded together. Furthermore, even when high-power RF is applied during the HARC process, raising the temperature of the base 113 and the electrostatic chuck 114, it is possible to reduce residual stress generated between the base 113 and the electrostatic chuck 114. This reduction in the generated residual stress appropriately suppresses breakage or warpage due to the difference in linear expansion coefficient between the base 113 and the electrostatic chuck 114 during the HARC process.

Furthermore, with the substrate support 11 of this embodiment, the base 113 and the electrostatic chuck 114 are diffusion-bonded, thereby improving the thermal response of the substrate support 11 and the substrate W during etching. In other words, for example, in etching processes in which RF is applied alternately at high and low power, the thermal response can be improved, making it possible to repeatedly switch the RF power in a shorter time.

Furthermore, with the substrate support 11 of variant 1, residual stress generated during manufacturing or substrate processing can be alleviated by deformation of the grooves 116, making it possible to further suppress warping or damage to the electrostatic chuck 114 or base 113.

Furthermore, with the substrate support of variant 2, the pressure of the heat transfer gas in the groove 116 can be controlled, thereby shortening the time required for the temperature of the substrate W to change during substrate processing. Furthermore, the heat transfer gas can be recovered and reused, enabling cost improvements and resource conservation.

The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

This application claims priority to U.S. Provisional Application No. 63/141,597, filed in the United States Patent and Trademark Office on January 26, 2021, the entire contents of which are incorporated herein by reference.

11: Substrate support 113: Base 114: Electrostatic chuck 115: Diffusion bonded portion C: Flow path W: Substrate

Claims (12)

a substrate support made of a first material and having an electrode disposed therein and configured to support a substrate;
a base having a flow path configured to allow a temperature control fluid for the substrate to flow therethrough, the base being made of a second material different from the first material;
a diffusion bond formed in a boundary region between the substrate support and the base;
Equipped with
a difference between the linear expansion coefficient of the first material and the linear expansion coefficient of the second material is 1.0×10 ⁻⁶ /° C. or less;
the first material comprises a silicon carbide-containing ceramic;
Substrate support. The substrate support of claim 1, wherein the diffusion bond includes the first material and the second material. The substrate support of claim 2, wherein the diffusion bond further includes a third material different from the first material and the second material. The substrate support according to any one of claims 1 to 3 , wherein the second material has a linear expansion coefficient of 7.0 x 10 ^-6 /°C to 9.0 ^{x 10 -6} /°C. The substrate support according to any one of claims 1 to 4 , wherein the second material is titanium or a titanium alloy. The substrate support according to any one of claims 1 to 5 , wherein the base has a plurality of grooves arranged concentrically on a surface facing the substrate support portion. The substrate support according to claim 6 , wherein each of the plurality of grooves has a plurality of regions divided in the circumferential direction. a heat transfer gas control system for supplying a heat transfer gas into the plurality of grooves and controlling a pressure of the heat transfer gas;
The heat transfer gas control system includes:
a heat transfer gas source;
a gas line connecting the plurality of grooves and the heat transfer gas supply source; and a pressure control device for controlling the pressure of the heat transfer gas supplied to the plurality of grooves.
a pump for reducing the pressure in the plurality of grooves;
a recovery tank for recovering the heat transfer gas supplied to the plurality of grooves;
Including,
8. A substrate support according to claim 6 or 7 . a step of bringing a bottom surface of a substrate support made of a first material, the bottom surface of the substrate support having an electrode provided therein and configured to support a substrate, into contact with an upper surface of a base made of a second material different from the first material, the base having a flow path configured to allow a temperature control fluid for the substrate to flow therethrough;
a step of diffusion bonding the substrate support and the base to form a diffusion bonded portion in a boundary region between the substrate support and the base;
Equipped with
a difference between the linear expansion coefficient of the first material and the linear expansion coefficient of the second material is 1.0×10 ⁻⁶ /°C or less;
the first material comprises a silicon carbide-containing ceramic;
A method for manufacturing a substrate support. The method for manufacturing a substrate support according to claim 9 , wherein the step of forming the diffusion bonded portion comprises hot pressing the substrate support and the base to form the diffusion bonded portion. The method for manufacturing a substrate support according to claim 10 , wherein the hot pressing is performed at a temperature of 2 MPa or more and 500° C. or less. a chamber;
A substrate support according to any one of claims 1 to 8 , which is arranged in the chamber;
A substrate processing apparatus comprising: