Evaporative cooling of electrostatic chucks

Abstract

To provide an evaporative cooling method of electrostatic chucks to be used in a substrate processing system.SOLUTION: A baseplate 202 of a substrate support assembly ESC 200 includes: a cavity between an upper region, a lower region, and sidewalls of the baseplate; a plurality of pillars 212 arranged in the cavity between the upper and lower regions; an inlet 220 to supply a liquid to the cavity 210;and an outlet 222 to vent vapor of the liquid. In another implementation, a baseplate of a substrate support assembly includes: first channel arranged in the baseplate; a second channel arranged above the first channel; a plurality of vertical channels connecting the first channel to the second channel; an inlet to supply a liquid to the first channel; and an outlet to vent vapor of the liquid from the second channel.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS: This application claims the benefit of U.S. Provisional Application No. 63 / 025,043, filed May 14, 2020. The entire disclosure of the above application is incorporated herein by reference.

[0002] The present disclosure relates generally to substrate processing systems, and more particularly to evaporative cooling of electrostatic chucks used in substrate processing systems. [Background technology]

[0003] The background art provided herein is intended to provide a general background to the present disclosure, and the work of the inventors named herein, to the extent described in this background art, along with aspects of the description that would not normally be considered prior art at the time of filing, are not admitted expressly or impliedly as prior art to the present disclosure.

[0004] A substrate processing system typically includes multiple processing chambers (also called processing modules) for performing deposition, etching, and other processes on substrates, such as semiconductor wafers. Examples of processes that may be performed on substrates include, but are not limited to, plasma-enhanced chemical vapor deposition (PECVD), chemically enhanced plasma vapor deposition (CEPVD), sputtering physical vapor deposition (PVD), atomic layer deposition (ALD), and plasma-enhanced ALD (PEALD). Further examples of processes that may be performed on substrates include, but are not limited to, etching (e.g., chemical etching, plasma etching, reactive ion etching, etc.) and cleaning processes.

[0005] During processing, a substrate is placed on a substrate support assembly (such as a pedestal or electrostatic chuck (ESC)) located in a processing chamber of a substrate processing system. Typically, a robot moves the substrates from one processing chamber to another in the order in which they are processed. During deposition, a gas mixture containing one or more precursors is introduced into the processing chamber and a plasma is ignited to activate a chemical reaction. During etching, a gas mixture containing an etching gas is introduced into the processing chamber and a plasma is ignited to activate a chemical reaction. The processing chamber is periodically cleaned by supplying a cleaning gas into the processing chamber and igniting a plasma. Summary of the Invention

[0006] The base plate of the substrate support assembly comprises a cavity between an upper region, a lower region and a sidewall of the base plate, a plurality of pillars disposed within the cavity between the upper and lower regions, an inlet for supplying liquid to the cavity, and an outlet for exhausting vapor of the liquid.

[0007] In another feature, the pillars are covered with a wicking material.

[0008] In another aspect, the cavity is cylindrical and the height of the cavity is less than the diameter of the cavity.

[0009] In another aspect, the pillar is cylindrical and extends from the bottom of the cavity to the top of the cavity.

[0010] In another aspect, the pillar is cylindrical and extends vertically from the bottom of the cavity to the top of the cavity.

[0011] In another aspect, the base plate and cavity are cylindrical, with the cavity extending radially along a diameter of the base plate.

[0012] In another feature, the inlet is smaller in size than the outlet.

[0013] In another feature, the inlet is adjacent a bottom of the cavity and the outlet is adjacent a top of the cavity.

[0014] In another feature, the base plate further comprises a channel disposed in the base plate above the cavity, the outlet connected to a first end of the channel, and a second end of the channel connected to a vent in the base plate.

[0015] In other features, the base plate and the cavity are cylindrical, the channel is helical, and the cavity and the channel extend radially along a diameter of the base plate.

[0016] In other features, the base plate and cavity are cylindrical, the flow passages are bifilar, and the cavity and flow passages extend radially along a diameter of the base plate.

[0017] In another feature, a second cavity is present between the cavity and the lower region of the base plate. The outlet is connected to the second cavity. The second cavity is connected to a vent in the base plate.

[0018] In another feature, the device includes a channel disposed in the base plate above the cavity and a second cavity between the cavity and a lower region of the base plate, the outlet connected to a first end of the channel and the second cavity, and the second end of the channel connected to respective vents in the base plate.

[0019] In another aspect, the flow channel is bifilar or helical.

[0020] In another aspect, the base plate is cylindrical and the cavity, the channel, and the second cavity extend radially across a diameter of the base plate.

[0021] In still other features, a base plate of a substrate support assembly includes a first flow path disposed within the base plate, a second flow path disposed above the first flow path, a plurality of vertical flow paths connecting the first flow path to the second flow path, an inlet for supplying liquid to the first flow path, and an outlet for exhausting vapor of the liquid from the second flow path.

[0022] In another feature, the second flow path has a larger cross section than the first flow path.

[0023] In another feature, the interior wall of the second flow channel is coated with a wicking material.

[0024] In another feature, the first and second flow paths are helical.

[0025] In another feature, the first and second flow paths are bifilar.

[0026] In another feature, the first and second flow paths are parallel to one another.

[0027] In another feature, the base plate is cylindrical and the first and second channels extend radially across a diameter of the base plate.

[0028] In another feature, the inlet is connected to a first end of the first flow path, the second end of the first flow path is terminated, the first end of the second flow path is terminated, and the second end of the second flow path is connected to the outlet.

[0029] In other features, the inlet is connected to a first end of the first flow path, and a second end of the first flow path is terminated. The base plate further includes a third flow path disposed above the second flow path. The first end of the second flow path is connected to a first end of the third flow path. The second end of the second flow path is terminated. The second end of the third flow path is connected to the outlet.

[0030] In other features, the second flow path has a larger cross section than the first flow path, and the third flow path has a larger cross section than the second flow path.

[0031] In another aspect, the third flow path is bifilar or helical and parallel to the first and second flow paths.

[0032] In other features, the first, second, and third flow paths are helical, with the third flow path helical in an opposite direction to the first and second flow paths.

[0033] In other features, the base plate is cylindrical and the first, second, and third channels extend radially across a diameter of the base plate.

[0034] In other features, the inlet is connected to a first end of the first flow path and a second end of the first flow path is terminated. The base plate further comprises a cavity between the first flow path and the bottom region of the base plate. The first end of the second flow path is connected to the cavity. The second end of the second flow path is terminated. The cavity is connected to the outlet.

[0035] In other features, the base plate is cylindrical and the first and second channels and the cavity extend radially across a diameter of the base plate.

[0036] In other features, the base plate further comprises a plurality of porous plugs, each having a first end connected to the first flow channel and a second end connected to a passageway connecting the first end of the second flow channel to the cavity.

[0037] In other features, a vertical channel connecting the first channel to the second channel extends below the first end of the porous plug toward the center of the first channel.

[0038] In other features, the inlet is connected to a first end of the first channel, and a second end of the first channel is terminated. The base plate further includes a third channel disposed above the second channel and a cavity between the first channel and the bottom region of the base plate. The first end of the second channel is connected to the first end of the third channel and the cavity. The second end of the second channel is terminated. The second end of the third channel and the cavity are connected to respective vents in the base plate.

[0039] In other features, the second flow path has a larger cross section than the first flow path, and the third flow path has a larger cross section than the second flow path.

[0040] In another aspect, the third flow path is bifilar or helical and parallel to the first and second flow paths.

[0041] In other features, the first, second, and third flow paths are helical, with the third flow path helical in an opposite direction to the first and second flow paths.

[0042] In other features, the base plate is cylindrical and the first, second and third channels and the cavity extend radially across a diameter of the base plate.

[0043] In other features, the base plate further includes a cooling system, a liquid level sensor, and a controller. The cooling system is configured to supply liquid to the inlet based on feedback from the outlet. The liquid level sensor is disposed in the first flow path to sense a level of liquid in the first flow path. The controller is configured to control the supply of liquid from the cooling system to the inlet based on the level of liquid in the evaporative cooling system.

[0044] In still other features, a substrate processing system includes a substrate support assembly; an evaporative cooling system disposed within the substrate support assembly; a liquid supply configured to supply liquid to the evaporative cooling system; a liquid level sensor disposed within the evaporative cooling system to detect a level of liquid in the evaporative cooling system; and a controller configured to control the supply of liquid from the liquid supply to the evaporative cooling system based on the level of liquid in the evaporative cooling system.

[0045] In other features, the substrate processing system further comprises a gas supply for supplying pressurized gas to the liquid supply and a pressure sensor for sensing a system pressure within the substrate support assembly, the controller being configured to control the supply of pressurized gas from the gas supply to the liquid supply based on the system pressure, and to control a pressure at which the liquid vaporizes based on the controlled supply of pressurized gas from the gas supply to the liquid supply.

[0046] In other features, an evaporative cooling system includes a cavity between an upper region, a lower region, and a sidewall of a substrate support assembly, and a plurality of pillars disposed within the cavity between the upper and lower regions, the pillars being coated with a wicking material. The evaporative cooling system includes an inlet for supplying liquid from a liquid supply to the cavity and an outlet for exhausting vapor of the liquid.

[0047] In another feature, the evaporative cooling system includes a channel disposed above the cavity in the substrate support assembly, the outlet connected to the channel, and the channel connected to a vent in the substrate support assembly.

[0048] In another feature, the evaporative cooling system includes a second cavity within the substrate support assembly between the cavity and the lower region of the substrate support assembly, the outlet connected to the second cavity, and the second cavity connected to a vent within the substrate support assembly.

[0049] In other features, the evaporative cooling system includes a channel disposed above the cavity within the substrate support assembly and a second cavity within the substrate support assembly between the cavity and a lower region of the substrate support assembly, the outlet connected to the channel and the second cavity, and the second cavity and the channel connected to respective vents within the substrate support assembly.

[0050] In other features, an evaporative cooling system includes a first flow path disposed within a substrate support assembly, a second flow path disposed within the substrate support assembly above the first flow path, and a plurality of vertical flow paths disposed within the substrate support assembly for connecting the first flow path to the second flow path, the evaporative cooling system including an inlet for supplying liquid from a liquid supply to the first flow path and an outlet for exhausting vapor of the liquid from the second flow path.

[0051] In another feature, the evaporative cooling system includes a third flow path disposed within the substrate support assembly above the second flow path, the third flow path being connected to the second flow path and the outlet, the second flow path having a larger cross-section than the first flow path, and the third flow path having a larger cross-section than the second flow path.

[0052] In another feature, the evaporative cooling system includes a cavity within the substrate support assembly between a first passage and a bottom region of the substrate support assembly, the second passage connected to the cavity, and the cavity connected to the outlet.

[0053] In other features, the evaporative cooling system includes a third flow path disposed within the substrate support assembly above the second flow path and a cavity within the substrate support assembly between the first flow path and a bottom region of the substrate support assembly, the second flow path connected to the third flow path and the cavity, and the third flow path and the cavity connected to respective vents within the substrate support assembly.

[0054] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief explanation of the drawings]

[0055] The present disclosure will become more fully understood from the detailed description and accompanying drawings set forth below.

[0056] [Figure 1A] 1 illustrates a first example substrate processing system in accordance with the present disclosure.

[0057] [Figure 1B] 1 illustrates a second example substrate processing system in accordance with the present disclosure.

[0058] [Figure 2A] 1 illustrates a first design of an evaporative cooling system in accordance with the present disclosure. [Figure 2B] 1 illustrates a first design of an evaporative cooling system in accordance with the present disclosure.

[0059] [Figure 3] Cross section of the first design.

[0060] [Figure 4] FIG. 1 illustrates a second design of an evaporative cooling system in accordance with the present disclosure.

[0061] [Figure 5] FIG. 10 is a top view of a first example of a second design using a bifilar flow channel.

[0062] [Figure 6] Cross-sectional view of the first example.

[0063] [Figure 7] FIG. 10 is a top view of a second example of a second design using a spiral flow channel.

[0064] [Figure 8]Cross-sectional view of the second example.

[0065] [Figure 9] 4 is a cross-sectional view of a first example of a third design of an evaporative cooling system according to the present disclosure, which adds a vapor flow path to the first design of FIGS. 2A, 2B, and 3. FIG.

[0066] [Figure 10] FIG. 9 is a cross-sectional view showing a second example of a third design in which a steam flow path is added to the second design of FIGS.

[0067] [Figure 11] FIG. 11 is a top view of the added steam flow path of FIG. 10;

[0068] [Figure 12] 12 is a cross-sectional view of the flow channel of FIG. 11.

[0069] [Figure 13] FIG. 9 is a top view of a fourth design of an evaporative cooling system according to the present disclosure, including a cavity under the second design of FIGS.

[0070] [Figure 14] Cross section of the fourth design.

[0071] [Figure 15] 14 is a cross-sectional view of the cavity of FIG. 13.

[0072] [Figure 16] FIG. 10 is a cross-sectional view of a fifth design of an evaporative cooling system according to the present disclosure, adding a phase separator to the fourth design.

[0073] [Figure 17A] FIG. 17 shows an example of a control system for controlling the evaporative cooling systems of FIGS. 2A to 16. [Figure 17B] FIG. 17 shows an example of a control system for controlling the evaporative cooling systems of FIGS. 2A to 16.

[0074] [Figure 18]FIG. 17C illustrates an example of a method for controlling the evaporative cooling system of FIGS. 2A to 17B.

[0075] In the drawings, the same numbers may be used to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE INVENTION

[0076] Typically, a cooling fluid is used to cool an electrostatic chuck (ESC). The cooling system of the present disclosure utilizes a specially designed evaporator inside the ESC along with a refrigerant fluid. Various examples of evaporators are described below. In particular, a cryogenic liquid (i.e., a liquid with a normal boiling point below −130° F. (−90° C.)) is vaporized within the ESC structure to provide cooling in a controlled manner, leading to efficient and repeatable cooling with effective heat transfer from the substrate to the cooled area. The cooling system removes a relatively high heat load from the ESC by operating down to cryogenic temperatures. The cooling system solves problems related to two-phase flow and provides efficient utilization of the cooling capacity of the cryogenic liquid. The cooling capacity of the cooling system is much higher at temperatures below −20° C. than systems that rely on heat transfer to a cooling fluid.

[0077] ESC cooling is typically performed using either high-pressure cooling gas or various liquid coolants. Disadvantages of these methods include their limited cooling capacity and / or limited operating temperature range. For example, closed-circuit liquid cooling systems become prohibitively expensive when operating temperatures drop below -20°C due to the need for multiple cooling stages. The coolant must be a material that exists as a liquid over extreme temperature ranges (e.g., -80°C to 80°C) and is not unacceptable due to corrosion or toxicity concerns. Such coolants are rare and expensive. Alternatively, a closed-flow gas stream may be used. However, to achieve cooling in the 1-5 kW range, the required gas flow is relatively large, requiring the gas to be compressed to pressures in the range of several hundred pounds per square inch.

[0078] For a pure substance, the latent heat of vaporization per kilogram is typically much higher than the enthalpy change when heating the medium by, say, 20°C, which may approach the maximum amount used in an ESC due to thermal uniformity considerations. This is why vaporization of the working medium is the cooling method used in most cooling systems. However, vaporization at the point of use (i.e., the ESC) has not typically been utilized because it requires vaporizing a significant flow of liquid within a limited space. Flowing a boiling liquid through a closed loop can lead to two-phase flow, which is relatively difficult to control in a stable manner. Depending on the surface energy involved, bubbles may form, or more commonly, plug flow is established with alternating plugs of gas and liquid as the gas region expands when the liquid boils. Thus, the velocity of these plugs increases dramatically along the cooling channel. Similarly, cooling efficiency decreases and relatively large back pressures are generated. Therefore, unless the design provides for an increased cross-sectional area of ​​the channel, such designs are plagued with heat transfer uniformity issues. Instead, as explained below, the evaporative cooling system of the present disclosure provides more controlled evaporation.

[0079] This disclosure is organized as follows: First, an example of a substrate processing system in which the cooling system of the present disclosure can be utilized is illustrated and described with reference to FIGS. 1A and 1B. Then, an example of a cooling system according to a first design is illustrated and described with reference to FIGS. 2A, 2B, and 3. An example of a cooling system according to a second design is illustrated and described with reference to FIGS. 4-8. Further designs are illustrated and described with reference to FIGS. 9-16. An example of a control system that can be used to control various cooling systems is illustrated and described with reference to FIGS. 17A and 17B. A method of controlling various cooling systems is illustrated and described with reference to FIG. 18.

[0080] FIG. 1A illustrates an example substrate processing system 10 for etching substrates, such as semiconductor wafers, using inductively coupled plasma according to the present disclosure. The substrate processing system 10 includes a coil driver circuit 11. In some examples, the coil driver circuit 11 includes an RF source 12, a pulsing circuit 14, and a tuning circuit (i.e., matching circuit) 13. The pulsing circuit 14 controls the transformer-coupled plasma (TCP) envelope of the RF signal generated by the RF source 12, varying the duty cycle of the TCP envelope between 1% and 99% during operation. The pulsing circuit 14 and the RF source 12 may be integrated or separate.

[0081] Tuning circuit 13 may be directly connected to induction coil 16. While substrate processing system 10 uses a single coil, some substrate processing systems may use multiple coils (e.g., an inner coil and an outer coil). Tuning circuit 13 tunes the output of RF source 12 to a desired frequency and / or a desired phase and matches the impedance of coil 16.

[0082] The dielectric window 24 is disposed along the top side of the processing chamber 28. The processing chamber 28 includes a substrate support (or pedestal) 30 for supporting a substrate 34. The substrate support 30 may include an electrostatic chuck (ESC), a mechanical chuck, or other types of chucks. The substrate support 30 includes a base plate 32. A ceramic plate 33 is disposed on the upper surface of the base plate 32. A thermal resistance layer 36 may be disposed between the ceramic plate 33 and the base plate 32. The substrate 34 is disposed on the ceramic plate 33 during processing. A plurality of heaters 35 are disposed within the ceramic plate 33 for heating the substrate 34 during processing. For example, the heaters 35 may include printed wiring embedded within the ceramic plate 33.

[0083] Base plate 32 further includes an evaporative cooling system 38 for cooling substrate support 30. Evaporative cooling system 38 cools substrate support 30 using liquid supplied by liquid supply system 39. Evaporative cooling system 38 may include any of the evaporative cooling systems 38 described below with reference to Figures 2A-15.

[0084] Processing gases are supplied to processing chamber 28, and plasma 40 is generated inside processing chamber 28. Plasma 40 etches the exposed surface of substrate 34. An RF source 50, pulsing circuitry 51, and bias matching circuitry 52 may be used to bias substrate support 30 and control ion energy during processing.

[0085] A gas supply system 56 may be used to supply a process gas mixture to the processing chamber 28. The gas supply system 56 may include a process gas / inert gas source 57, a gas metering system 58 (such as valves and mass flow controllers), and a manifold 59. A gas injector 63 may be positioned in the center of the dielectric window 24 and is used to inject the gas mixture from the gas supply system 56 into the processing chamber 28. Additionally or alternatively, the gas mixture may be injected from the side of the processing chamber 28.

[0086] A temperature controller 64 may be connected to the heater 35 and may be used to control the heater 35 and thereby control the temperature of the substrate support 30 and the substrate 34. The temperature controller 64 may be in communication with a liquid supply system 39 to control the flow of liquid through the evaporative cooling system 38 to cool the substrate support 30. For example, as shown and described with reference to FIG. 17A, the liquid supply system 39 may include a liquid source, a pressurized gas supply, a valve, and a pressure sensor. For example, as shown and described with reference to FIG. 17B, the liquid supply system 39 may include a cooling system. The evaporative cooling system 38 may include a liquid level sensor (e.g., elements 230 and 412 shown in FIGS. 2A, 2B, 17A, and 17B) to sense the liquid level in the evaporative cooling system 38, as described in more detail below. The temperature controller 64 may control the flow of liquid through the evaporative cooling system 38 based on feedback from the liquid level sensor and the pressure sensor.

[0087] An exhaust system 65 includes valves 66 and pumps 67 for controlling the pressure within the process chamber 28 and / or for removing reactants from the process chamber 28 by purging or evacuation. A controller 70 may be used to control the etching process. The controller 70 controls the components of the substrate processing system 10. The controller 70 monitors system parameters and controls the supply of gas mixtures, ignition, maintenance, and extinguishing of plasma, removal of reactants, supply of coolant, etc. Additionally, the controller 70 may control various aspects of the coil driver circuit 11, the RF source 50, and the bias matching circuit 52.

[0088] 1B illustrates another example substrate processing system 100 including a processing chamber 102 configured to generate a capacitively coupled plasma. While this example is described in the context of plasma-enhanced chemical vapor deposition (PECVD), the teachings of the present disclosure may be applied to other types of substrate processing, such as atomic layer deposition (ALD), plasma-enhanced ALD (PEALD), CVD, or other processes involving etching.

[0089] The substrate processing system 100 includes a process chamber 102 that houses the other components of the substrate processing system 100 and confines the RF plasma (if utilized). The process chamber 102 includes an upper electrode 104 and an electrostatic chuck (ESC) 106 or other type of substrate support. During operation, a substrate 108 is placed on the ESC 106.

[0090] For example, the upper electrode 104 may include a gas distribution apparatus 110 (such as a showerhead) that introduces and distributes process gases into the processing chamber 102. The gas distribution apparatus 110 may include a stem portion with one end connected to the top surface of the processing chamber 102. The base portion of the showerhead is generally cylindrical and flares radially outward from the opposite end of the stem portion away from the top surface of the processing chamber 102. The substrate-facing surface, or faceplate, of the showerhead base portion includes a plurality of outlets or features (e.g., slots or through-holes) through which vaporized precursors, process gases, or purge gases flow.

[0091] The ESC 106 includes a base plate 112 that functions as a lower electrode. A ceramic plate 114 includes a heater 152 for heating the substrate 108 and is disposed on the upper surface of the base plate 112. The heater 152 includes printed wiring embedded in the ceramic plate 114. A thermal resistance layer 116 may be disposed between the ceramic plate 114 and the base plate 112. The base plate 112 includes an evaporative cooling system 118 for cooling the ESC 106. The evaporative cooling system 118 may include any of the evaporative cooling systems 38 described below with reference to FIGS. 2A-15.

[0092] When a plasma is utilized, an RF generation system (or RF source) 120 generates and outputs an RF voltage to one of the upper electrode 104 and the lower electrode (e.g., the base plate 112 of the ESC 106). The other of the upper electrode 104 and the base plate 112 may be DC grounded, AC grounded, or floating. For example, the RF generation system 120 may include an RF generator 122 that generates RF power that is supplied to the upper electrode 104 or the base plate 112 by a matching / distribution network 124. In another example, not shown, a plasma may be generated inductively or remotely before being supplied to the processing chamber 102.

[0093] A gas delivery system 130 includes one or more gas sources 132-1, 132-2, ..., and 132-N (collectively, gas sources 132), where N is an integer greater than zero. The gas sources 132 are connected to a manifold 140 by valves 134-1, 134-2, ..., and 134-N (collectively, valves 134) and mass flow controllers 136-1, 136-2, ..., and 136-N (collectively, mass flow controllers 136). A vapor delivery system 142 delivers vaporized precursors to the manifold 140 or to a separate manifold (not shown) connected to the processing chamber 102. The output of the manifold 140 is delivered to the processing chamber 102. The gas sources 132 may deliver process gases, cleaning gases, or purge gases.

[0094] The temperature controller 150 is used to control the temperature of the ESC 106 and the substrate 108 by controlling the heater 152. The temperature controller 150 may be in communication with a liquid supply system 154 to control the flow of liquid through the evaporative cooling system 118 to cool the ESC 106. For example, as shown and described with reference to FIG. 17A , the liquid supply system 154 may include a liquid source, a pressurized gas supply, a valve, and a pressure sensor. For example, as shown and described with reference to FIG. 17B , the liquid supply system 154 may include a cooling system. The evaporative cooling system 118 may include a liquid level sensor (e.g., elements 230 and 412 shown in FIGS. 2A, 2B, 11A, and 17B) to sense the liquid level in the evaporative cooling system 118, as described in more detail below. The temperature controller 150 may control the flow of liquid through the evaporative cooling system 118 based on feedback from the liquid level sensor and the pressure sensor.

[0095] A valve 156 and a pump 158 may be used to evacuate reactants from the processing chamber 102. A system controller 160 controls the components of the substrate processing system 100.

[0096] In the following evaporative cooling systems shown in Figures 2A-16, liquid is vaporized in a controlled manner by migration to a wicking surface, as described in detail below. Various implementations are provided by way of example in Figures 2A-16. Examples of control systems that may be used to control various evaporative cooling systems are shown in Figures 17A and 17B. Methods for controlling various evaporative cooling systems are shown in Figure 18.

[0097] 2A, 2B, and 3 show a first design of an evaporative cooling system according to the present disclosure. In FIG. 2A, ESC 200 includes a base plate 202. A ceramic plate 204 is disposed on base plate 202. A plurality of heaters 206 (e.g., printed wiring) are disposed within ceramic plate 204. A thermal resistance layer 203 may be disposed between heaters 206 and base plate 202. A substrate (not shown) is disposed on ceramic plate 204 during processing.

[0098] A cavity 210 is defined within the base plate 202 and is shown in more detail in Figure 3. The base plate 202 may be formed of a material with high thermal conductivity, including a metal (such as aluminum or titanium) or an alloy (such as AlSiC or SiC). Figure 3 shows a cross-section of the base plate 202 taken along the dotted line shown in Figure 2A. In the cross-section, the top of the cavity 210 is shown as open for illustrative purposes.

[0099] As shown in Figure 3, the cavity 210 is cylindrical with a height less than its diameter. The cavity 210 includes pillars 212 that extend from the top to the bottom of the cavity 210. The pillars 212 may also be referred to as protrusions or projections. By way of example only, the pillars 212 are shown as cylindrical. Alternatively, the pillars 212 may have other shapes. The pillars 212 have a shape that provides a relatively large surface area.

[0100] The interior of cavity 210 is lined with wicking material 214. In FIG. 2B, wicking material 214 also covers the top surfaces of pillars 212, thereby enabling heat transfer from the liquid over a larger area. For example, wicking material 214 may comprise a metal coating with a relatively large surface area. For example, wicking material 214 may comprise plasma-sprayed aluminum or twin-wire arc-sprayed aluminum. Alternatively, electroplating may be used to increase the surface area of ​​wicking material 214. In other examples, wicking material 214 may comprise sintered glass beads or sintered polymer spheres (e.g., polyethylene), and the beads, in both cases, may have a diameter of approximately 10 to 300 μm.

[0101] Cavity 210 includes one or more inlet ports 220 for receiving the liquid to be vaporized and one or more outlet ports 222 for removal of the vaporized vapor. The outlet ports are larger than the inlet ports 220. Heat flows from the upper region of base plate 202 above cavity 210 to pillars 212. The liquid in cavity 210 migrates to wicking material 214 and is vaporized in a controlled manner by the heat transferred from pillars 212 to wicking material 214.

[0102] Cavity 210 includes one or more liquid level sensors 230 that are used in conjunction with a control system (see examples shown in FIGS. 17A and 17B) to maintain a substantially constant liquid level in the lower portion of cavity 210. The liquid rises to the surface of wicking material 214 and vaporizes at the surface of wicking material 214 in a controlled manner without large bubble formation. The vaporized gas exits cavity 210 through a vent (i.e., outlet port 222) and may be further utilized to cool ESC 200, as described below.

[0103] This design provides sufficient heat transfer from the wicking material 214 to the region of the ESC 200 above the cavity 210 while maximizing the length of the boundary between the cavity material and the cavity space (to provide maximum wicking area).

[0104] Generally speaking, a substrate support assembly such as the ESC 200 includes a base plate 202 and a ceramic plate 204 disposed on the base plate 202. The ceramic plate 204 includes one or more heaters 206 for heating a substrate disposed on the ceramic plate 204 during processing. The base plate 202 includes a cavity 210 between (i.e., defined by) an upper region, a lower region, and a sidewall of the base plate 202. The cavity 210 is cylindrical, and the height of the cavity 210 is less than the diameter of the cavity 210. The cavity 210 extends radially along the diameter of the base plate 202. A plurality of pillars 212 are disposed within the cavity 210 between the upper and lower regions of the base plate 202. For example, the pillars 212 are cylindrical and extend from the bottom of the cavity 210 to the top of the cavity 210. For example, pillars 212 extend vertically (i.e., upright) from the bottom of cavity 210 to the top of cavity 210. Pillars 212 are covered with wicking material 214. Base plate 202 includes an inlet 220 for supplying liquid to cavity 210 and an outlet 222 for exhausting liquid vapor from base plate 202. Inlet 220 is smaller in size than outlet 222. Inlet 220 is adjacent (i.e., close to) the bottom of cavity 210, and outlet 222 is adjacent (i.e., close to) the top of cavity 210.

[0105] 4 illustrates a second design of an evaporative cooling system according to the present disclosure. In the second design, the ESC 300 is provided with a pair of parallel flow paths disposed within the base plate of the ESC 300. In the illustrated example, a pair of flow paths including a lower flow path 302 and an upper flow path 304 are disposed within the base plate of the ESC 300. The lower and upper flow paths 302, 304 are also referred to as the first and second flow paths or the liquid and vapor flow paths, respectively, throughout this disclosure.

[0106] The lower and upper channels 302, 304 are provided with small spaced apart connectors (also called connecting channels) 306 that extend generally perpendicularly between the lower and upper channels 302, 304. Liquid is not intended to flow through the lower channel 302 and boil therein. A sufficient liquid flow rate is maintained within the lower channel 302 to minimize boiling of liquid within the lower channel 302. The upper channel 304 has a cross-sectional area significantly larger than the lower channel 302. In one embodiment, the interior walls of the upper channel 304 are lined with a wicking material 310. The wicking material 310 may be similar to the wicking material 214 shown in FIGS. 2A and 2B. In some embodiments, the wicking material 310 may be omitted.

[0107] During operation, liquid is pumped from the lower channel 302 through the connector 306 into the larger upper channel 304. Heat flows into the upper channel 304 from the upper region of the base plate above the upper channel 304. Vaporization of the liquid occurs in the upper channel 304, and the gas (e.g., steam) formed by the vaporization flows along the upper channel 304 to the outlet port (shown in FIG. 5 ). The configuration of the lower and upper channels 304, 304 and connector 306 separates the liquid flow from the gas flow, preventing problems due to two-phase flow.

[0108] The layout of the lower and upper channels 302, 304 may be such that the liquid transport channel (i.e., the lower channel 302) is vertically below the gas channel (i.e., the upper channel 304). The layout is parallel to the plane of the substrate. The lower and upper channels 302, 304 are also parallel to each other.

[0109] 5 and 6 show a first example of implementing the lower and upper flow channels 302, 304 within the ESC 300 according to the second design. In FIG. 5, the lower flow channel 302 (shown in dotted lines) and the upper flow channel 304 (shown in solid lines) disposed within the base plate 301 of the ESC 300 are bifilar to minimize temperature gradients. The lower flow channel 302 includes an inlet 312 for liquid, and the upper flow channel 304 includes an outlet 314 for vapor. The vapor flow channel (i.e., the upper flow channel 304) is dead-ended. In one embodiment, the liquid flow channel (i.e., the lower flow channel 302) is dead-ended. In another embodiment, the liquid flow channel (i.e., the lower flow channel 302) is open-ended. The lower and upper flow channels 302, 304 are stacked. That is, the vapor channels (i.e., upper channels 304) are closer to the substrate (i.e., the top surface of ESC 300) and are stacked above the liquid channels (i.e., lower channels 302). Fabricating these stacked channels can be difficult, but Figure 6 shows one solution.

[0110] 5-14, the lower and upper flow channels 302, 304 are not drawn to scale. Additionally, any size differences between the lower and upper flow channels 302, 304 shown in the top views and the corresponding cross-sectional views are not actual differences. As shown in FIG. 4, in FIGS. 5-14, the upper flow channel 304 has a larger cross-sectional area than the lower flow channel 302. Additionally, in FIGS. 5-14, the thermal resistance layer 203, although present, is not shown.

[0111] 6, a rectangular channel 320 located in the base plate 301 of the ESC 300 is closed by a structure which itself contains or defines the liquid channel 302, with a nozzle 322 penetrating the structure in the direction of the vapor channel forming a connector 306. This structure is held within the ESC body (i.e., base plate 301), and the liquid channel 302 is closed by plate 324.

[0112] 7 and 8 show a second example of implementing the lower and upper flow channels 302, 304 within the ESC 300 according to a second design. In FIG. 7, the lower and upper flow channels 302, 304 disposed within the base plate 301 of the ESC 300 are two separate spiral flow channels instead of the bifurcated flow channels shown in FIG. 5. The lower flow channel 302-1 includes an inlet 312-1 for liquid, and the upper flow channel 304-1 includes an outlet 314-1 for vapor. The lower and upper flow channels 302-1, 304-1 are stacked similarly to the flow channels shown and described above with reference to FIGS. 4-6. The lower and upper flow channels 302-1, 304-1 are provided with a spaced apart connecting flow channel 306, as shown in FIG. 4, extending generally perpendicularly between the lower and upper flow channels 302-1, 304-1. The spiral lower and upper channels 302-1, 304-1 terminate near the center of the base plate 301. Figure 8 shows the stacked structure of the lower and upper spiral channels 302-1, 304-1. Figure 8 is similar to Figure 6 and is shown for reference only, so it will not be described again here.

[0113] Throughout this disclosure, the bifilar lower and upper flow channels 302, 304 shown in Figure 5 and the helical lower and upper flow channels 302-1, 304-1 shown in Figure 7 are collectively referred to as the lower and upper flow channels 302, 304. Additionally, as already mentioned above, the lower and upper flow channels 302, 304 are also referred to throughout this disclosure as the first and second flow channels or the liquid and vapor flow channels, respectively. Regardless of the configuration (i.e., bifilar or helical), the lower and upper flow channels 302, 304 are provided with a spaced apart connecting flow channel 306 that extends generally perpendicularly between the lower and upper flow channels 302, 304.

[0114] Generally speaking, a substrate support such as the ESC 300 includes a base plate 301 and a ceramic plate 204 disposed on the base plate 301. The ceramic plate 204 includes one or more heaters 206 for heating a substrate disposed on the ceramic plate 204 during processing. The base plate 301 includes a first flow channel (i.e., liquid flow channel) 302 disposed therein. The base plate 301 includes a second flow channel (i.e., vapor flow channel) 304 disposed above the first tubular flow channel 302. The first and second flow channels 302, 304 may be circular (tubular), rectangular, or polygonal. The base plate 301 includes a plurality of vertical flow channels (i.e., connectors) 306 connecting the first flow channel 302 to the second flow channel 304. The base plate 301 includes an inlet for supplying liquid to the first flow channel 302 and an outlet for exhausting liquid vapor from the second flow channel 304. For example, the first and second channels 302, 304 are helical or bifilar. The first and second channels 302, 304 are arranged parallel to the substrate. The base plate 301 is cylindrical, and the first and second channels 302, 304 extend radially across the diameter of the base plate 301. In one embodiment, an inlet is connected to a first end of the first channel 302, a second end of the first channel 302 is terminated, a first end of the second channel 304 is terminated, and a second end of the second channel 304 is connected to an outlet. In another embodiment, the first end of the second channel 304 is connected to another outlet.

[0115] In the second design shown in FIGS. 4-8 , control of the flow of liquid from the liquid flow path 302 to the vapor flow path 304 may be governed by a sensor that detects excess liquid in the vapor flow path 304. In some embodiments, a liquid level sensor may be used. Other embodiments may use a sensor that detects droplets or liquid plugs emerging from the vapor flow path 304. The liquid level sensor may be of any type. For example, the liquid level sensor may include a hot wire resistance liquid level sensor. In these sensors, a wire is heated by a substantially constant current (e.g., supplied by temperature controller 64 or 150 shown in FIGS. 1A and 1B ). Upon contact with a liquid (which has a high heat removal capacity), the temperature of the wire drops sharply, increasing its resistance, which may be detected as a voltage drop (e.g., by temperature controller 64 or 150 shown in FIGS. 1A and 1B ). The designs of the present disclosure are not limited by these sensor selections; many other options are possible and may be utilized.

[0116] In the second design shown in Figures 4-8 (and also in the first design shown in Figures 2A, 2B, and 3), the gas (i.e., vapor) generated in the upper flow channel 304 by boiling the liquid with heat from the upper region of the ESC 300 above the upper flow channel 304 is still near its boiling point and can be used to further control the temperature of the ESC 300. The gas may be used as a medium with relatively low thermal conductivity (i.e., an insulating medium), as shown and described below with reference to Figures 9-14.

[0117] The surface where the liquid is evaporating may be at a temperature very close to the boiling point of the liquid, which is unlikely to be the desired ESC operating temperature. Therefore, it is necessary to allow for a temperature gradient to exist within the ESC. Conversely, the walls of the channel containing the gas (i.e., vapor) may be at a completely different temperature relative to the gas. Therefore, the cooling system can be further improved by passing the gas through additional channels stacked above and / or below the evaporation system (i.e., above and / or below the upper channel 304 shown in Figures 4-8 and above and / or below the cavity 210 shown in Figures 2A, 2B, and 3). Similar to the upper channel 304, this second gas loop (i.e., additional vapor channel) can be designed to provide the best (i.e., most spatially uniform) heat removal pattern.

[0118] 9 and 10 show an example of an ESC with a second vapor flow path 352 above the evaporator system shown in FIGS. 2A-3 and 4-8. In FIG. 9, the second vapor flow path 352 is located above the cavity 210 shown in FIGS. 2A, 2B, and 3. The second vapor flow path 352 may be spiral-shaped. FIG. 11 shows a top view of the second vapor flow path 352. The second vapor flow path 352 provides a thermal gradient within the upper region of the base plate 202.

[0119] In FIG. 10, the second vapor flow path 352 is disposed above the upper flow path 304 shown in FIGS. 4 to 8. The second vapor flow path 352 is connected to the upper flow path 304 and receives vapor from the upper flow path 304. The second vapor flow path 352 may be spiral. The second vapor flow path 352 spirals in the opposite direction to the lower and upper flow paths 302, 304. The second vapor flow path 352 is disposed parallel to the lower and upper flow paths 302, 304. FIG. 11 shows a top view of the second vapor flow path 352. The second vapor flow path 352 provides a thermal gradient within the upper region of the base plate 301.

[0120] 11 and 12 show an example of a second vapor flow path 352 implemented in the second design of the cooling system shown in FIGS. 4-8. FIG. 11 shows a top view of an example of the second vapor flow path 352. In the example, the lower and upper flow paths 302, 304 are shown as helical (see FIGS. 7 and 8), but the lower and upper flow paths 302, 304 may also be bifilar, as shown in FIGS. 5 and 6. The lower and upper flow paths 302, 304 are stacked, as already described above. The second vapor flow path 352 is stacked above the upper flow path 304. The upper flow path 304 is dead-ended. In one embodiment, the lower flow path 302 is dead-ended. In another embodiment, the lower flow path 302 is not dead-ended. One end (i.e., the open end) of the upper flow path 304 is connected to the second vapor flow path 352 near the center of the base plate 301. The opposite end of the second vapor passage 352 emits vapor through an outlet 354. Figure 12 is similar to Figure 10 and, except for the addition of the second vapor passage 352, is also similar to Figure 6 and will not be described again here.

[0121] 13-15 show an example of implementing an insulating layer below the cooling system described above to reduce parasitic heating of the liquid from the bottom region of the ESC base plate. This example is shown for the cooling system shown in FIGS. 4-8. Although not shown, the same design may be implemented for the cooling systems shown in FIGS. 2A, 2B, and 3. In the example, a cavity 390 is defined within the base plate 301 below the lower channel 302 (i.e., between the lower channel 302 and the bottom of the base plate 301). For example, the cavity 390 may be a simple cylindrical space, as shown. Alternatively, although not shown, the steam flow may be guided by an appropriate wall. Steam exits the upper channel 304 through outlet 314, enters the cavity 390, and exits the cavity 390 through outlet 392. Although the lower and upper channels 302, 304 are shown as bifilar, the lower and upper channels 302, 304 may instead be helical as shown in Figures 7 and 8. Figure 14 is similar to Figure 16 except for the addition of cavity 390 and will not be described again here. Figure 15 shows a cross-sectional view of cavity 390.

[0122] The following description explicitly illustrates the connections between the second steam flow path 352 and / or cavity 390 and the elements of the cooling system shown in Figures 2A-3 and 4-8 when the second steam flow path 352 and / or cavity 390 are added to the cooling system shown in Figures 2A-3 and 4-8.

[0123] When the second vapor flow path 352 shown in FIGS. 9 and 11 is added to the cooling system shown in FIGS. 2A, 2B, and 3, the base plate 202 further includes a flow path (i.e., a second vapor flow path) 352 disposed within the base plate 202 above the cavity 210. The flow path 352 may be circular (i.e., tubular), rectangular, or polygonal. The outlet 222 is connected to a first end of the flow path 352, and a second end of the flow path 352 is connected to a vent within the base plate 202. For example, the base plate 202 and the cavity 210 are cylindrical, and the flow path 352 is helical or bifilar. The cavity 210 and the flow path 352 extend radially along the diameter of the base plate 202.

[0124] 13 is added to the cooling system shown in Figures 2A, 2B, and 3, the base plate 202 further includes a cavity 390 (referred to as a second cavity 390 to distinguish it from cavity 210) between the cavity 210 and the lower region of the base plate 202. The outlet 222 is connected to the second cavity 390, which is connected to a vent in the base plate 202.

[0125] 9 and 11 and the cavity 390 shown in FIG. 13 are both added to the cooling system shown in FIGS. 2A, 2B, and 3, the base plate 202 further includes a channel (i.e., a second vapor channel) 352 disposed above the cavity 210 within the base plate 202. The base plate 202 further includes a cavity 390 (referred to as a second cavity 390 to distinguish it from the cavity 210) between the cavity 210 and a lower region of the base plate 202. The outlet 222 is connected to a first end of the channel 352 and the second cavity 390. The second cavity 390 and the second end of the channel 352 are connected to respective vents within the base plate 202. The channel 352 is helical or bifilar. The base plate 202 is cylindrical, with the cavity 210 , the flow passage 352 , and the second cavity 390 extending radially across the diameter of the base plate 202 .

[0126] When the second vapor flow path 352 shown in FIGS. 10-12 is added to the cooling system shown in FIGS. 4-8, an inlet in the base plate 301 is connected to a first end of the first flow path (i.e., liquid flow path) 302, and a second end of the first flow path 302 is terminated. The base plate 301 further includes a second vapor flow path (referred to as a third flow path) 352 disposed above the second flow path (i.e., vapor flow path) 304. The first end of the second flow path 304 is connected to a first end of the third flow path 352. The second end of the second flow path 304 is terminated. The second end of the third flow path 352 is connected to an outlet in the base plate 301. The third flow path 352 has a larger cross section than the second flow path 304. The third flow path 352 is helical or bifilar. The base plate 301 is cylindrical and the first, second and third channels 302 , 304 , 352 extend radially across the diameter of the base plate 301 .

[0127] When the cavity 390 shown in FIGS. 13-14 is added to the cooling system shown in FIGS. 4-8, the inlet in the base plate 310 is connected to a first end of the first flow path (i.e., liquid flow path) 302. The second end of the first flow path 302 is terminated. The base plate 301 further includes a cavity 390 between the first flow path 302 and the bottom region of the base plate 301. The first end of the second flow path (i.e., vapor flow path) 304 is connected to the cavity 390. The second end of the second flow path 304 is terminated. The cavity 390 is connected to an outlet in the base plate 301. The base plate 301 is cylindrical, and the first and second flow paths 302, 304 and the cavity 390 extend radially across the diameter of the base plate 301.

[0128] When the second air flow passage 352 and cavity 390 shown in Figures 10-14 are added to the cooling system shown in Figures 4-8, the inlet in the base plate 301 is connected to the first end of the first air flow passage 302. The second end of the first air flow passage 302 is terminated. The base plate 301 further includes a third air flow passage 352 disposed above the second air flow passage 304. The base plate 301 further includes a cavity 390 between the first air flow passage 390 and the bottom region of the base plate 301. The first end of the second air flow passage 304 is connected to the first end of the third air flow passage 352 and the cavity 390. The second end of the second air flow passage 352 is terminated. The second end of the third air flow passage 352 and the cavity 390 are connected to respective vents in the base plate 301. The third air flow passage 352 has a larger cross-section than the second air flow passage 304. The third air flow passage 352 is helical or bifilar. The base plate 301 is cylindrical, and the first, second and third channels 302 , 304 , 352 and cavity 390 extend radially across the diameter of the base plate 301 .

[0129] Figure 16 is a cross-sectional view of another example of an evaporative cooling system with a phase separator that separates vapor from liquid to ensure only liquid can enter upper flow channel 304 from lower flow channel 302. Figure 16 is similar to Figure 14 except that a porous plug 303 has been added to lower flow channel 302 and a straw-like passage 305 has been added extending nozzle 322 between upper and lower flow channels 304, 302, as shown.

[0130] For example, the porous plug 303 may include a sintered metal element that allows vapor to flow relatively easily and is more resistant to liquid flow than vapor flow. The porous plug 303 is positioned near the upper end of the lower flow passage 302. For example, the porous plug 303 may be positioned as close to the nozzle 322 as possible. The porous plug 303 is connected to a passage 307 that connects the outlet 314 of the upper flow passage 304 to the cavity 390. Therefore, any vapor that may be generated in the lower flow passage 302 may escape through the porous plug 303 to the cavity 390 instead of entering the upper flow passage 304, allowing only liquid from the lower flow passage 302 to enter the upper flow passage 304.

[0131] To further ensure separation of vapor and liquid within the lower flow channel 302 and ensure that only liquid from the lower flow channel 302 can enter the upper flow channel 304, the nozzle 322 between the upper and lower flow channels 304, 302 may be extended downward into the lower flow channel 302 by a straw-like passage 305. For example, the straw-like passage 305 may extend from the nozzle 322 into the lower flow channel 302 to at least a height lower than the porous plug 303, preferably to the center of the lower flow channel 322.

[0132] Liquids that can be utilized in the refrigeration systems of Figures 1-16 for purposes described herein can include liquid gases and refrigerant fluids. Examples of liquid gases include ammonia, liquid nitrogen, liquid argon, or other liquid noble gases (i.e., inert gases). Examples of refrigerant fluids include R404a and R134a. Higher boiling point fluids may also be used in ESCs configured to operate at higher temperatures.

[0133] FIG. 17A illustrates a system 400 that can be used in the refrigeration systems of FIGS. 2A-16 to adjust the boiling point of a liquid in accordance with the present disclosure. By varying the pressure at which the liquid vaporizes, some adjustment of the boiling point of the liquid can be obtained. To achieve such adjustment, system 400 provides backpressure regulation using a valve. For example, the valve can include a spring-activated check valve or a computer-programmable active throttle valve.

[0134] The system 400 includes an ESC 402 (which may be any of the ESCs described above with reference to Figures 2A-15), a liquid source 404, a pressurized gas supply 406, a first valve V1, a second valve V2, and a controller 410 (e.g., controller 64, 70, 170, or 150 shown in Figures 1A and 1B).

[0135] A liquid source 404 supplies a liquid (e.g., a liquid gas or refrigerant fluid as described above) to the ESC 402 (e.g., to the cavity 210 shown in FIGS. 2A-3 or to the lower flow path 302 shown in FIGS. 4-14). A pressurized gas supply 406 supplies pressurized gas to the liquid source 404 via a first valve V1. The first valve V1 is used to control the pressure of the liquid, while the second valve V2 is a variable valve and is used to control the flow of liquid through the system 400.

[0136] A pressure sensor 408 measures the system pressure P and provides it to a controller 410. The controller 410 opens a first valve V1 to supply pressurized gas from the pressurized gas supply 406. The pressurized gas has a pressure greater than the maximum pressure required for P to reach a predetermined level.

[0137] The height (i.e., liquid level) of the liquid in the ESC 402 (e.g., in the cavity 210 shown in FIGS. 2A-3 or in the lower flow path 302 shown in FIGS. 4-14) is controlled by the second valve V2. When the liquid level sensor 412 (e.g., the liquid level sensor 230 shown in FIGS. 2A-2B or a similar sensor used in FIGS. 4-14) indicates that the liquid level in the ESC 402 (e.g., in the cavity 210 shown in FIGS. 2A-3 or in the lower flow path 302 shown in FIGS. 4-8) is below a first set point, the controller 410 increases the conductance through the second valve V2, thereby allowing an increase in the flow rate of liquid from the liquid source 404 to the ESC 402. When the liquid level in the ESC 402 reaches a second set point, the controller 410 partially closes the second valve V2.

[0138] Pressure changes can provide significant changes in the vaporization temperature of a liquid. For example, if ammonia is used as a liquid, the boiling point can change from -30°C to 10°C with an increase in pressure from 1 bar to 4 bar. Alternatively, the refrigerant R404a is available with a boiling point between -50°C and 0°C over a similar pressure range.

[0139] In some embodiments, the vapor generated by boiling the liquid may be collected, cooled, liquefied, and returned to an evaporative cooling system within the ESC 402. The ESC 402 then functions as the evaporator of a closed-loop cooling system that can be operated efficiently and uniformly with the cooling system of the present disclosure implemented in the ESC 402. In other embodiments, the vapor may be vented to the atmosphere or, in some cases, such as nitrogen (when dry nitrogen is used throughout the facility by boiling liquid nitrogen), to utilization in the tool's facilities.

[0140] FIG. 17B illustrates a system 450 that can be used with the cooling systems of FIGS. 2A-16. System 450 is similar to system 400 illustrated in FIG. 17A, except that system 450 includes cooling system 452 instead of elements 406, V1, and 404 of system 400. Cooling system 452 is a closed-loop cooling system that supplies deeply subcooled liquid to ESC 402. Cooling system 452 ensures that only liquid, without any vapor phase, is supplied to ESC 402, thereby reducing the difficulty of managing two-phase flow. In some applications, system 450 can be used in place of the phase-separated design illustrated in FIG. 16. Valve V2 is optional and can be used to adjust the pressure of the liquid boiling within the evaporative cooling system of ESC 402.

[0141] FIG. 18 illustrates a method 500 for controlling the cooling system described above. For example, the method may be performed by the controller 410 of FIGS. 17A and 17B. At step 502, method 500 monitors the liquid level in the cooling system. At step 504, method 500 determines whether the liquid level in the cooling system is less than or equal to a first set point. If the liquid level in the cooling system is not less than or equal to the first set point, method 500 continues to monitor the liquid level in the cooling system at step 502. If the liquid level in the cooling system is less than or equal to the first set point, method 500 supplies fluid to the cooling system at step 506. At step 508, method 500 determines whether the liquid level in the cooling system is greater than or equal to a second set point. If the liquid level in the cooling system is not greater than or equal to the first set point, method 500 continues to supply liquid to the cooling system at step 506 until the liquid level in the cooling system is greater than or equal to the second set point. If the liquid level in the cooling system is greater than or equal to the first set point, the method 500 returns to step 502 .

[0142] The foregoing description is merely exemplary in nature and is not intended to limit the disclosure, its applications, or uses. The broad teachings of the present disclosure may be embodied in a variety of forms. Accordingly, while the present disclosure includes specific examples, the true scope of the disclosure is not limited to those examples, as other variations will become apparent from a study of the drawings, specification, and claims that follow.

[0143] It should be understood that one or more steps included in a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Furthermore, although each of the embodiments is described as having certain features, any one or more of the features described with respect to any embodiment of the present disclosure can be implemented in any of the other embodiments and / or can be combined with any of the features of the other embodiments, even if the combination is not expressly described. In other words, the above-described embodiments are not mutually exclusive, and it is within the scope of the present disclosure to substitute one or more embodiments for one another.

[0144] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers) are described using various terms, such as "connected," "engaged," "coupled," "adjacent," "adjacent," "on top of," "above," "below," and "disposed." When describing a relationship between first and second elements in this disclosure, unless expressly stated as "direct," the relationship may be a direct relationship where no other intervening elements exist between the first and second elements, or an indirect relationship where one or more intervening elements exist (spatially or functionally) between the first and second elements. As used herein, the phrase "at least one of A, B, and C" should be interpreted to mean the logical (A or B or C) using a non-exclusive logical OR, and not to mean "at least one of A, at least one of B, and at least one of C."

[0145] In some embodiments, the controller is part of a system, which may be part of the examples described above. Such a system may include semiconductor processing equipment, such as one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling the operation of the system before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as a "controller" and may control various components or subcomponents of the system.

[0146] The controller may be programmed to control any of the processes disclosed herein, such as supply of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid supply settings, position and motion settings, and wafer movement in and out of tools and other moving tools and / or load locks connected or coupled to a particular system, depending on the process requirements and / or type of system.

[0147] Generally, a controller may be defined as electronic equipment having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software).

[0148] Program instructions may be communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing particular processes on or for semiconductor wafers or instructions to the system. The operational parameters, in some embodiments, may be part of a recipe defined by a process engineer to accomplish one or more processing steps during the processing of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of the wafer.

[0149] In some embodiments, the controller may be part of or connected to a computer that is integrated with, connected to, or otherwise networked with the system, or a combination thereof. For example, the controller may be in the "cloud" or may be all or part of a fab host computer system that can enable remote access to wafer processing. The computer may enable remote access to the system to monitor the current progress of a manufacturing operation, examine the history of past manufacturing operations, or examine trends or performance indicators from multiple manufacturing operations, to change parameters of a current process, set processing steps according to a current process, or initiate a new process.

[0150] In some examples, a remote computer (e.g., a server) may provide process recipes to the system over a network (which may include a local network or the Internet). The remote computer may include a user interface that allows for entry or programming of parameters and / or settings, which are communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the process steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool the controller is configured to interface with or control.

[0151] Thus, as described above, the controller may be distributed, such as by having one or more separate controllers that are networked and operate toward a common purpose (such as the processing and control described herein). One example of a distributed controller for such purposes is one or more integrated circuits on the chamber that communicate with one or more remotely located integrated circuits (e.g., located at the platform level or remotely as part of a remote computer) that cooperate to control processing in the chamber.

[0152] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing system that may be associated with or utilized in the fabrication and / or manufacturing of semiconductor wafers.

[0153] As described above, depending on the processing step or steps being performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to carry containers of wafers to or from tool locations and / or load ports within a semiconductor fabrication factory.

Claims

1. A base plate of a substrate support assembly, comprising: a cavity between an upper region, a lower region, and a sidewall of the base plate; a plurality of pillars disposed within the cavity between the upper region and the lower region; an inlet for supplying a liquid to the cavity; an outlet for venting vapor of said liquid; A base plate comprising:

2. 2. The base plate according to claim 1, The pillars are covered with a wicking material, the base plate.

3. 2. The base plate according to claim 1, The cavity is cylindrical, and the height of the cavity is less than the diameter of the cavity.

4. 2. The base plate according to claim 1, The pillar is cylindrical and extends from the bottom of the cavity to the top of the cavity.

5. 2. The base plate according to claim 1, The pillar is cylindrical and extends vertically from the bottom of the cavity to the top of the cavity.

6. 2. The base plate according to claim 1, A base plate, wherein the base plate and the cavity are cylindrical, and the cavity extends radially along a diameter of the base plate.

7. 2. The base plate according to claim 1, The base plate, wherein the inlet is smaller in size than the outlet.

8. 2. The base plate according to claim 1, The base plate, wherein the inlet is adjacent a bottom of the cavity and the outlet is adjacent a top of the cavity.

9. 10. The base plate of claim 1, further comprising: a channel disposed within the base plate above the cavity; the outlet is connected to a first end of the flow path; A base plate, wherein a second end of the channel is connected to a vent in the base plate.

10. 10. The base plate of claim 9, the base plate and the cavity are cylindrical; the flow path is spiral; The cavity and the flow passage extend radially along a diameter of the base plate.

11. 10. The base plate of claim 9, the base plate and the cavity are cylindrical; the flow path is bifilar; The cavity and the flow passage extend radially along a diameter of the base plate.

12. 10. The base plate of claim 1, further comprising: a second cavity between the cavity and the lower region of the base plate; the outlet is connected to the second cavity; The second cavity is connected to a vent in the base plate.

13. 10. The base plate of claim 1, further comprising: a channel disposed within the base plate above the cavity; a second cavity between the cavity and the lower region of the base plate; Equipped with the outlet is connected to a first end of the flow channel and the second cavity; A base plate, wherein the second cavity and the second end of the channel are connected to respective vents in the base plate.

14. 14. The base plate of claim 13, The base plate, wherein the flow channel is bifilar or helical.

15. 14. The base plate of claim 13, The base plate is cylindrical, and the cavity, the flow channel, and the second cavity extend radially across a diameter of the base plate.

16. A base plate of a substrate support assembly, comprising: a first flow path disposed within the base plate; a second flow path disposed above the first flow path; a plurality of vertical channels connecting the first channels to the second channels; an inlet for supplying a liquid to the first flow path; an outlet for exhausting vapor of the liquid from the second flow path; A base plate comprising:

17. 17. The base plate of claim 16, The second flow path has a larger cross section than the first flow path.

18. 17. The base plate of claim 16, The inner wall of the second flow path is covered with a wicking material.

19. 17. The base plate of claim 16, The base plate, wherein the first flow path and the second flow path are spiral.

20. 17. The base plate of claim 16, The base plate, wherein the first flow path and the second flow path are bifilar.

21. 17. The base plate of claim 16, The first flow path and the second flow path are parallel to each other.

22. 17. The base plate of claim 16, The base plate is cylindrical, and the first and second flow channels extend radially across a diameter of the base plate.

23. 17. The base plate of claim 16, the inlet is connected to a first end of the first flow path; a second end of the first flow path is terminated; a first end of the second flow path is terminated; A base plate, wherein a second end of the second flow path is connected to the outlet.

24. 17. The base plate of claim 16, the inlet is connected to a first end of the first flow path; a second end of the first flow path is terminated; The base plate further comprises: a third flow path disposed above the second flow path; a first end of the second flow path connected to a first end of the third flow path; a second end of the second flow path is terminated; A base plate, wherein a second end of the third flow path is connected to the outlet.

25. 25. The base plate of claim 24, The second flow path has a larger cross section than the first flow path, and the third flow path has a larger cross section than the second flow path.

26. 25. The base plate of claim 24, The third flow path is bifilar or helical and parallel to the first and second flow paths.

27. 25. The base plate of claim 24, The base plate, wherein the first flow path, the second flow path, and the third flow path are spiral, and the third flow path spirals in an opposite direction to the first and second flow paths.

28. 25. The base plate of claim 24, The base plate is cylindrical, and the first flow path, the second flow path, and the third flow path extend radially across a diameter of the base plate.

29. 17. The base plate of claim 16, the inlet is connected to a first end of the first flow path; a second end of the first flow path is terminated; The base plate further comprises: a cavity between the first channel and a bottom region of the base plate; a first end of the second flow path connected to the cavity; a second end of the second flow path is terminated; The cavity is connected to the outlet.

30. 30. The base plate of claim 29, The base plate is cylindrical, and the first and second flow channels and the cavity extend radially across a diameter of the base plate.

31. 30. The base plate of claim 29, The base plate further comprises a plurality of porous plugs, each of the porous plugs having a first end connected to the first flow path and a second end connected to a passage connecting the first end of the second flow path to the cavity.

32. 32. The base plate of claim 31 , The vertical channel connecting the first channel to the second channel extends below the first end of the porous plug toward the center of the first channel.

33. 17. The base plate of claim 16, the inlet is connected to a first end of the first flow path; a second end of the first flow path is terminated; The base plate further comprises: a third flow path disposed above the second flow path; a cavity between the first channel and a bottom region of the base plate; Equipped with a first end of the second flow path connected to a first end of the third flow path and to the cavity; a second end of the second flow path is terminated; A base plate, wherein the second end of the third flow channel and the cavity are connected to respective vents in the base plate.

34. 34. The base plate of claim 33, The second flow path has a larger cross section than the first flow path, and the third flow path has a larger cross section than the second flow path.

35. 34. The base plate of claim 33, The third flow path is bifilar or helical and parallel to the first and second flow paths.

36. 34. The base plate of claim 33, wherein the first flow path, the second flow path, and the third flow path are spiral, and the third flow path spirals in an opposite direction to the first flow path and the second flow path.

37. 34. The base plate of claim 33, The base plate is cylindrical, and the first, second, and third flow paths and the cavity extend radially across a diameter of the base plate.

38. 17. The base plate of claim 16, further comprising: a cooling system configured to supply the liquid to the inlet based on feedback from the outlet; a liquid level sensor disposed in the first flow path to sense a liquid level in the first flow path; a controller configured to control the supply of liquid from the cooling system to the inlet based on the level of the liquid in the evaporative cooling system; and A base plate comprising:

39. 1. A substrate processing system, comprising: a substrate support assembly; an evaporative cooling system disposed within the substrate support assembly; a liquid supply configured to supply a liquid to the evaporative cooling system; a liquid level sensor disposed within the evaporative cooling system for sensing the level of the liquid in the evaporative cooling system; a controller configured to control a supply of liquid from the liquid supply to the evaporative cooling system based on the level of the liquid in the evaporative cooling system; A substrate processing system comprising:

40. 40. The substrate processing system of claim 39, further comprising: a gas supply for supplying pressurized gas to the liquid supply; a pressure sensor for sensing a system pressure within the substrate support assembly; Equipped with The controller controlling the supply of pressurized gas from the gas supply to the liquid supply based on the system pressure; a substrate processing system configured to control a pressure at which the liquid vaporizes based on the controlled supply of the pressurized gas from the gas supply to the liquid supply.

41. 40. The substrate processing system of claim 39, wherein the evaporative cooling system comprises: a cavity between an upper region, a lower region, and a sidewall of the substrate support assembly; a plurality of pillars disposed within the cavity between the upper and lower regions, the pillars being covered with a wicking material; an inlet for supplying the liquid from the liquid supply portion to the cavity; an outlet for venting vapor of said liquid; A substrate processing system comprising:

42. 42. The substrate processing system of claim 41, wherein the evaporative cooling system comprises: a channel disposed within the substrate support assembly above the cavity; the outlet is connected to the flow path; The flow path is connected to a vent in the substrate support assembly.

43. 42. The substrate processing system of claim 41, wherein the evaporative cooling system comprises: a second cavity within the substrate support assembly between the cavity and the lower region of the substrate support assembly; the outlet is connected to the second cavity; The second cavity is connected to a vent in the substrate support assembly.

44. 42. The substrate processing system of claim 41, wherein the evaporative cooling system comprises: a channel disposed within the substrate support assembly above the cavity; a second cavity within the substrate support assembly between the cavity and the lower region of the substrate support assembly; Equipped with the outlet is connected to the flow path and the second cavity; The second cavity and the flow path are connected to respective vents in the substrate support assembly.

45. 40. The substrate processing system of claim 39, wherein the evaporative cooling system comprises: a first flow path disposed within the substrate support assembly; a second flow path disposed within the substrate support assembly above the first flow path; a plurality of vertical channels disposed within the substrate support assembly for connecting the first channels to the second channels; an inlet for supplying the liquid from the liquid supply unit to the first flow path; an outlet for exhausting vapor of the liquid from the second flow path; A substrate processing system comprising:

46. 46. ​​The substrate processing system of claim 45, wherein the evaporative cooling system comprises: a third flow path disposed within the substrate support assembly above the second flow path; the third flow path is connected to the second flow path and the outlet, the second flow path has a larger cross section than the first flow path; The third flow path has a larger cross section than the second flow path.

47. 46. ​​The substrate processing system of claim 45, wherein the evaporative cooling system comprises: a cavity within the substrate support assembly between the first channel and a bottom region of the substrate support assembly; the second flow path is connected to the cavity; The cavity is connected to the outlet.

48. 46. ​​The substrate processing system of claim 45, wherein the evaporative cooling system comprises: a third flow path disposed within the substrate support assembly above the second flow path; a cavity within the substrate support assembly between the first channel and a bottom region of the substrate support assembly; Equipped with the second flow path is connected to the third flow path and the cavity; The third flow path and the cavity are connected to respective vents in the substrate support assembly.

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