WO2025264393A1

WO2025264393A1 - Coolant flow control system for substrate supports

Info

Publication number: WO2025264393A1
Application number: PCT/US2025/032407
Authority: WO
Inventors: Dan Marohl; Saurish DAS; Atithya Umesh KALLANNAVAR; Sathisha KRISHNAPPA; Ambarish CHHATRE
Original assignee: Lam Research Corp
Current assignee: Lam Research Corp
Priority date: 2024-06-17
Filing date: 2025-06-05
Publication date: 2025-12-26
Anticipated expiration: 2026-12-17

Abstract

A system comprises a substrate support comprising a cooling channel, a coolant supply configured to supply a coolant, and a flow control system configured to receive the coolant from the coolant supply and to supply the coolant to the cooling channel and to selectively divert a portion of the coolant from flowing to the cooling channel. The flow control system comprises a valve and a meter. The valve is configured to receive coolant fluid from a coolant supply, to supply a first portion of the coolant fluid to a cooling channel in a substrate support, and to selectively divert a second portion of the coolant fluid from flowing to the cooling channel. The meter is configured to collect coolant flow rate information from the valve, and the flow control system is configured to divert a portion of the coolant fluid to the coolant supply based on the information.

Description

COOLANT FLOW CONTROL SYSTEM FOR SUBSTRATE SUPPORTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/661 ,005, filed on June 17, 2024. The entire disclosure of the application referenced above is incorporated herein by reference.

FIELD

[0002] The present disclosure relates generally to substrate processing systems and more particularly to a coolant flow control system for substrate supports used in substrate processing systems.

BACKGROUND

[0003] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] A substrate processing system (also called a tool) typically includes a plurality of processing chambers (also called process modules) to perform deposition, etching, and other treatments of substrates such as semiconductor wafers. Examples of deposition processes that may be performed on a substrate include, but are not limited to, plasma enhanced chemical vapor deposition (PECVD), chemically enhanced plasma vapor deposition (CEPVD), atomic layer deposition (ALD), and plasma enhanced ALD (PEALD). Examples of etching processes that may be performed on a substrate include, but are not limited to, chemical etching, plasma etching, and reactive ion etching processes. Additional examples of the processes that can be performed in processing chambers include cleaning processes used to periodically clean the processing chambers.

[0005] During processing, a substrate is arranged on a substrate support assembly such as a pedestal or an electrostatic chuck (ESC) arranged in a processing chamber of the substrate processing system. A computer-controlled robot typically transfers substrates from one processing chamber to another in a sequence in which the substrates are to be processed. During deposition, gas mixtures including one or more precursors are introduced into the processing chamber, and plasma is struck to activate chemical reactions. During etching, gas mixtures including etch gases are introduced into the processing chamber, and plasma is struck to activate chemical reactions. The processing chambers are periodically cleaned by supplying a cleaning gas into the processing chamber and striking plasma.

SUMMARY

[0006] A system comprises a substrate support comprising a cooling channel, a coolant supply configured to supply a coolant, and a flow control system configured to receive the coolant from the coolant supply and to supply the coolant to the cooling channel and to selectively divert a portion of the coolant from flowing to the cooling channel.

[0007] In additional features, the coolant supply is configured to supply the coolant at a constant flow rate. The flow control system is configured to receive the coolant from the coolant supply at the constant flow rate and to supply the coolant to the cooling channel at a selected flow rate that is different than the constant flow rate.

[0008] In additional features, the flow control system is configured to divert the portion of the coolant from flowing to the cooling channel in response to a selected flow rate at which the flow control system supplies the coolant to the cooling channel being different than a flow rate at which the coolant supply is configured to supply the coolant.

[0009] In additional features, the flow control system comprises a valve configured to receive the coolant from the coolant supply at a constant flow rate, to supply the coolant to the cooling channel at a selected flow rate, and to divert the portion of the coolant from flowing to the cooling channel.

[0010] In additional features, the substrate support comprises a heater. The system further comprises a controller configured to control a temperature of the substrate support by one or more of controlling power supplied to the heater, controlling a flow rate at which the flow control system supplies the coolant to the cooling channel, and controlling the portion of the coolant diverted from flowing to the cooling channel.

[0011] In additional features, the cooling channel comprises an inlet and an outlet. The coolant supply comprises and inlet and an outlet. The flow control system comprises a three-port valve. A first port of the three-port valve is connected to the outlet of the coolant supply. A second port of the three-port valve is connected to the inlet of the cooling channel. A third port of the three-port valve is coupled to the inlet of the coolant supply.

[0012] In additional features, the first port of the three-port valve receives the coolant from the outlet of the coolant supply at a constant flow rate. The three-port valve is configured to (i) selectively divert a portion of the coolant through the third port of the three-port valve to the inlet of the coolant supply and (ii) supply the coolant through the second port of the three-port valve to the inlet of the cooling channel at a selected flow rate.

[0013] In additional features, the three-port valve is configured to divert the portion of the coolant from flowing through the second port of the three-port valve to the inlet of the cooling channel in response to the selected flow rate being less than the constant flow rate.

[0014] In additional features, the substrate support comprises a heater. The system further comprises a controller configured to control power supplied to the heater, and to control the three-port valve to (i) selectively divert the portion of the coolant and (ii) supply the coolant to the inlet of the cooling channel at the selected flow rate to control a temperature of the substrate support.

[0015] In additional features, the cooling channel comprises an inlet and an outlet. The coolant supply comprises and inlet and an outlet. The flow control system comprises a two-port valve. A first port of the two-port valve is connected to the outlet of the coolant supply and to the inlet of the cooling channel. The outlet of the cooling channel is connected to the inlet of the coolant supply. A second port of the two-port valve is coupled to the outlet of the cooling channel and to the inlet of the coolant supply.

[0016] In additional features, the flow control system comprises a flow adjuster. The flow adjuster comprises an inlet connected to the second port of the two-port valve and comprises an outlet coupled to the outlet of the cooling channel and to the inlet of the coolant supply. The first port of the two-port valve is configured to receive the coolant from the outlet of the coolant supply at a constant flow rate. The two-port valve and the flow adjuster are configured to (i) selectively divert a portion of the coolant through the second port of the two-port valve and the outlet of the flow adjuster to the inlet of the coolant supply and (ii) supply the coolant to the inlet of the cooling channel at a selected flow rate. [0017] In additional features, the two-port valve and the flow adjuster are configured to divert the portion of the coolant from flowing to the inlet of the cooling channel in response to the selected flow rate being less than the constant flow rate.

[0018] In additional features, the substrate support comprises a heater. The system further comprises a controller configured to control power supplied to the heater, and to control the two-port valve and the flow adjuster to (i) selectively divert the portion of the coolant and (ii) supply the coolant to the inlet of the cooling channel at the selected flow rate to control a temperature of the substrate support.

[0019] In still other features, a flow control system comprises a valve and a meter. The valve is configured to receive coolant fluid from a coolant supply, to supply a first portion of the coolant fluid to a cooling channel in a substrate support, and to selectively divert a second portion of the coolant fluid from flowing to the cooling channel. The meter is configured to collect coolant flow rate information from the valve, and to send the collected coolant flow rate to a controller. The flow control system is configured to divert a portion of the coolant fluid to the coolant supply based on the collected coolant flow rate.

[0020] In additional features, the valve is a three-port valve. A first port of the three- port valve is configured to connect to an outlet of the coolant supply. A second port of the three-port valve is configured to connect to an inlet of a cooling channel of the substrate support. A third port of the three-port valve is configured to be coupled to an outlet of the cooling channel and to an inlet of the coolant supply.

[0021] In additional features, the first port of the three-port valve is configured to receive the coolant fluid from the outlet of the coolant supply at a constant flow rate. The three-port valve is configured to (i) selectively divert a portion of the coolant fluid through the third port of the three-port valve to the inlet of the coolant supply and (ii) supply the coolant fluid through the second port of the three-port valve to the inlet of the cooling channel at a selected flow rate.

[0022] In additional features, the three-port valve is configured to divert the portion of the coolant fluid from flowing through the second port of the three-port valve to the inlet of the cooling channel in response to the selected flow rate being different than the constant flow rate. [0023] In additional features, a system comprises the flow control system and further comprises the substrate support. The substrate support comprises a heater. The system further comprises a controller configured to control a temperature of the substrate support by one or more of controlling power supplied to the heater, and controlling the three-port valve to (i) selectively divert the portion of the coolant fluid and (ii) supply the coolant fluid to the inlet of the cooling channel at the selected flow rate.

[0024] In additional features, the valve is a two-port valve. A first port of the two-port valve is configured to connect to an outlet of the coolant supply and to an inlet of the cooling channel. An outlet of the cooling channel is configured to connect to an inlet of the coolant supply. A second port of the two-port valve is configured to be coupled to the outlet of the cooling channel and to the inlet of the coolant supply.

[0025] In additional features, the flow control system comprises a flow adjuster. The flow adjuster comprises an inlet configured to connect to the second port of the two-port valve and comprises an outlet configured to be coupled to the outlet of the cooling channel and the inlet of the coolant supply. The first port of the two-port valve is configured to receive the coolant fluid from the outlet of the coolant supply at a constant flow rate. The two-port valve and the flow adjuster are configured to (i) selectively divert a portion of the coolant fluid through the second port of the two-port valve and the outlet of the flow adjuster to the inlet of the coolant supply and (ii) supply the coolant fluid to the inlet of the cooling channel at a selected flow rate while the coolant supply supplies the coolant fluid at the constant flow rate.

[0026] In additional features, the two-port valve and the flow adjuster are configured to divert the portion of the coolant fluid from flowing to the inlet of the cooling channel in response to the selected flow rate being less than the constant flow rate.

[0027] In additional features, a system comprises the flow control system and further comprises the substrate support. The substrate support comprises a heater. The system further comprises a controller configured to control a temperature of the substrate support by one or more of controlling power supplied to the heater, and controlling the two-port valve and the flow adjuster to (i) selectively divert the portion of the coolant fluid and (ii) supply the coolant fluid to the inlet of the cooling channel at the selected flow rate.

[0028] In still other features, a method of controlling temperature of a substrate support comprises receiving, at a valve, a coolant from a coolant supply; and controlling the valve to supply a first portion of the coolant to a cooling channel in the substrate support and to selectively divert a second portion of the coolant from flowing to the cooling channel.

[0029] In additional features, the method further comprises controlling the temperature of the substrate support by controlling the valve while the coolant supply supplies the coolant at a constant flow rate.

[0030] In additional features, the method further comprises controlling the valve to divert the second portion of the coolant from flowing to the cooling channel based on a selected flow rate at which the first portion of the coolant is supplied to the cooling channel in the substrate support while the coolant supply supplies the coolant at a constant flow rate.

[0031] In additional features, the method further comprises one or more of controlling a flow rate of the first portion of the coolant supplied by the valve to the cooling channel, and controlling an amount of the second portion of the coolant diverted by the valve from flowing to the cooling channel.

[0032] In additional features, the method further comprises controlling power supplied to a heater of the substrate support, controlling a flow rate at which the first portion of the coolant is supplied by the valve to the cooling channel in the substrate support, or controlling an amount of the second portion of the coolant diverted by the valve from flowing to the cooling channel.

[0033] In additional features, the method further comprises controlling a selected flow rate at which the first portion of the coolant is supplied by the valve to the cooling channel in the substrate support, or controlling an amount of the second portion of the coolant diverted by the valve from flowing to the cooling channel.

[0034] In additional features, the method further comprises controlling a selected flow rate at which the first portion of the coolant is supplied by the valve to the cooling channel in the substrate support, or controlling power supplied to a heater of the substrate support.

[0035] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0037] FIG. 1 shows an example of a substrate processing system comprising a substrate support that utilizes a coolant flow control system according to the present disclosure;

[0038] FIG. 2 shows another example of a substrate processing system comprising a substrate support that utilizes the coolant flow control system according to the present disclosure;

[0039] FIG. 3 shows a block diagram of the coolant flow control system used in the substrate processing systems of FIGS. 1 and 2 according to the present disclosure;

[0040] FIG. 4 shows a method of controlling flow of coolant through the substrate support using the coolant flow control system of FIG. 3;

[0041] FIG. 5 shows a block diagram of one example of implementing the coolant flow control system of FIG. 3 according to the present disclosure;

[0042] FIG. 6 shows a method of controlling flow of coolant through the substrate support using the coolant flow control system of FIG. 5;

[0043] FIG. 7 shows a block diagram of another example of implementing the coolant flow control system of FIG. 3 according to the present disclosure; and

[0044] FIG. 8 shows a method of controlling flow of coolant through the substrate support using the coolant flow control system of FIG. 7.

[0045] In the drawings, reference numbers may be reused to identify similar and/or identical elements.

DETAILED DESCRIPTION

[0046] In some processes, when a substrate is arranged on a substrate support (also called a pedestal) in a processing chamber for processing, the pedestal is heated to pre-heat the substrate before performing a process on the substrate. The pedestal is also heated and cooled during the processing of the substrate. The pedestal comprises one or more heaters and cooling channels to control the temperature of the pedestal. For example, the pedestal may comprise an inner heater that heats an inner region of the pedestal and an outer heater that heats an outer region of the pedestal. A power supply supplies power to the heaters. The cooling channels are arranged below the heaters and extend across the pedestal. A coolant supply system (also called a chiller) supplies a coolant to the cooling channels at a constant flow rate and temperature set for the process to be performed on the substrate.

[0047] During the pre-heating stage, a duty cycle of the heaters is increased while the coolant supply system supplies the coolant to the cooling channels at the constant flow rate. Typically, the duty cycle of the heaters is increased to near maximum value so that the substrate temperature may reach a target value required by the process. The difference between heater temperature and coolant temperature causes thermal shock to the pedestal. Thermal shock is caused by rapid changes in the temperature of portions of the pedestal that results in a transient mechanical load on the pedestal. The transient mechanical load is caused by the differential expansion of the different portions of the pedestal due to the temperature changes. The differential expansion causes strain that can cause cracking and structural failure in the pedestal. Further, increasing the duty cycle of the heaters during the pre-heating stage also consumes a large amount of power.

[0048] Subsequently, when plasma is struck during the processing of the substrate, the plasma additionally heats the pedestal. To control the temperature of the pedestal, the duty cycle of the heaters is adjusted. While the duty cycle of the heaters can be adjusted, the coolant supply system is designed to supply the coolant at a relatively constant flow rate, which cannot be changed much (beyond a narrow range) without damaging the coolant supply system. That is, varying the flow rate of the coolant supplied by the coolant supply system beyond a narrow range can damage the coolant supply system. To prevent the damage to the coolant supply system, the duty cycle of the heaters is adjusted to control the temperature of the pedestal. Again, the changes in the duty cycle of the heaters and the difference between heater temperature and coolant temperature cause thermal shock to the pedestal.

[0049] The present disclosure solves the above problems by providing a coolant flow control system to control the flow rate of the coolant externally from the coolant supply system while also reducing the duty cycle of the heaters. The coolant flow control system is external to the coolant supply system and allows controlling the flow rate of the coolant through the pedestal while allowing the coolant supply system to supply the coolant at the designed constant flow rate. Allowing the coolant supply system to supply the coolant at the designed constant flow rate (i.e., not changing the flow rate of the coolant supply system) prevents damage to the coolant supply system. Instead of changing the flow rate of the coolant supply system, the coolant flow control system of the present disclosure, which is interposed between the coolant supply system and the substrate support, changes the flow rate of the coolant as needed. The coolant flow control system reduces the flow rate at which the coolant is supplied to the pedestal during the pre-heating stage. Reducing the flow rate of the coolant allows the heaters to be operated at a reduced duty cycle during the pre-heating stage, which saves power consumed by the heaters during the pre-heating stage.

[0050] The combination of the reduced flow rate of the coolant and the reduced duty cycle of the heaters allows the substrate to be heated to the target temperature during the pre-heating stage while reducing the power consumed by the heaters during the pre-heating stage. The reduced duty cycle of the heaters during the pre-heating stage saves the power consumed by the heaters during the pre-heating stage. Additionally, the reduced duty cycle of the heaters during the pre-heating stage leaves more head room to increase the duty cycle of the heaters if a process requires the substrate to be heated to a higher temperature.

[0051] Subsequently, when plasma is struck to process the substrate, the plasma heats the substrate and the substrate support. To maintain the temperature of the substrate at the target temperature, the duty cycle of the heaters in the substrate support can be further reduced and the flow rate of the coolant through the substrate support can be increased using the coolant flow control system without changing the flow rate of the coolant supply system. By further reducing the duty cycle of the heaters, the power consumed by the heaters is further reduced. Moreover, depending on the temperature requirements of the process performed on the substrate, since there is more head room to increase the duty cycle of the heaters, the duty cycle of the heaters can be increased if the process requires the substrate to be heated to a higher temperature. The coolant supply system continues to supply the coolant at the designed constant flow rate throughout the pre-heating stage and during substrate processing using plasma, which prevents damage to the coolant supply system.

[0052] Accordingly, the coolant flow control system of the present disclosure provides a control knob to adjust the temperature of the substrate support using the combination of the duty cycle of the heaters and the adjustable flow rate of the coolant without changing the flow rate of the coolant supply system. The control knob can be used throughout the pre-heating stage and during substrate processing (e.g., during substrate processing using plasma). The coolant flow control system not only saves the power consumed by the heaters but also extends the temperature range to which the substrate can be heated without requiring additional power for the heaters, which allows performing processes requiring higher temperatures. The coolant flow control system also helps extend the life of the coolant supply system since the flow rate of the coolant supply system is not changed. Further, since the duty cycle of the heaters is reduced and the flow rate of the coolant can be adjusted during pre-heating and substrate processing, the temperature differential between the heaters and the cooling channels in the substrate support is also reduced, which reduces the thermal shock on the substrate support.

[0053] Furthermore, during substrate processing (e.g., with plasma on), the coolant flow rate is a tradeoff between the heater power and the local thermal non-uniformity at substrate level, which requires precise control of the coolant flow rate and the heater power to maintain thermal uniformity at substrate level. The coolant flow control system provides the precise control of the coolant flow rate, which the coolant supply system cannot provide without damaging the coolant supply system. The precise control of substrate thermal non-uniformity is not an issue during the pre-heating stage, which provides additional flexibility for the coolant flow control system to adjust the temperature of the substrate support during pre-heating stage. These and other features of the present disclosure are described below in further detail.

[0054] The present disclosure is organized as follows. Initially, examples of substrate processing systems in which the coolant flow control system can be used are shown and described with reference to FIGS. 1 and 2. A general block diagram of the coolant flow control system and the method of controlling the temperature of the substrate support using the coolant flow control system are shown and described with reference to FIGS. 3 and 4. Two examples of implementing the coolant flow control system and respective methods of controlling the temperature of the substrate support are shown and described with reference to FIGS. 5-8.

EXAMPLES OF SUBSTRATE PROCESSING SYSTEM

[0055] FIG. 1 shows an example of a substrate processing system 10 comprising a processing chamber 28 that utilizes the coolant flow control system of the present disclosure. While only one processing chamber is shown for example, the substrate processing system 10 may comprise additional processing chambers. The additional processing chambers may perform other processes (e.g., deposition) on substrates. The coolant flow control system can also be used with a processing chamber in which a deposition process is performed. The processing chamber 28 uses inductively coupled plasma to etch substrates. Other processing chambers of the substrate processing system 10 may use other types of plasma (e.g., capacitively coupled plasma, remote plasma, etc.).

[0056] The substrate processing system 10 comprises a coil driving circuit 11 to generate a plasma 41 in the processing chamber 28 during substrate processing and chamber cleaning as described below. The coil driving circuit 11 includes a radio frequency (RF) source 12, a pulsing circuit 14, and a tuning circuit (i.e., matching circuit) 13. The RF source 12 generates an RF signal. The pulsing circuit 14 controls a transformer coupled plasma (TCP) envelope of the RF signal and varies a duty cycle of TCP envelope (e.g., between 1% and 99%) during operation. The pulsing circuit 14 and the RF source 12 can be combined or separate. The tuning circuit 13 may be directly connected to an inductive coil 16. While a single coil is shown, the substrate processing system 10 may comprise a plurality of coils (e.g., inner and outer coils) to generate the plasma 41. The tuning circuit 13 tunes an output of the RF source 12 to a desired frequency and/or a desired phase, and matches an impedance of the inductive coil 16.

[0057] A dielectric window 24 is arranged along a top end of the processing chamber 28. The processing chamber 28 comprises a substrate support (or pedestal) 30 to support a substrate 34. The substrate support 30 comprises an electrostatic chuck (ESC) that electrostatically clamps the substrate 34 to the substrate support 30. Alternatively, the substrate support 30 may use another type of clamping mechanism such as vacuum clamping or mechanical clamping to clamp the substrate 34 to the substrate support 30.

[0058] The substrate support 30 comprises a baseplate 32 and a ceramic plate 33. The baseplate 32 is made of a metallic material (e.g., aluminum or an aluminum alloy). The ceramic plate 33 is arranged on a top surface of the baseplate 32. A thermal resistance layer 36 made of an electrically and thermally insulating material is disposed between the ceramic plate 33 and the baseplate 32. The substrate 34 is arranged on the ceramic plate 33 during processing. The ceramic plate 33 comprises a clamping electrode 37 to clamp the substrate 34 to the ceramic plate 33. One or more heaters 35 are arranged in the ceramic plate 33 to heat the substrate 34 during processing. The heaters 35 are bonded to the ceramic plate 33 using a bonding material. A power supply 43 supplies power to the heaters 35.

[0059] The baseplate 32 of the substrate support 30 further comprises one or more cooling channels 38 to cool the substrate support 30. The cooling channels 38 use a coolant supplied by a coolant supply system 39 (also called a chiller) to regulate the temperature of the substrate support 30. In addition, a coolant flow control system (simply called a flow control system or FCS) 40 is connected between the coolant supply system 39 and the substrate support 30. The FCS 40 is described below in detail with reference to FIGS. 3-8. Briefly, the FCS 40 receives the coolant supplied by the coolant supply system 39 at a constant flow rate. The FCS 40 supplies the coolant to the cooling channels 38 at flow rates that can be different than the constant flow rate at which the coolant is supplied by the coolant supply system 39.

[0060] A gas delivery system 56 is used to supply various gases to the processing chamber 28. The gas delivery system 56 comprises gas sources 57 to supply the various gases. The gas sources 57 supply process gases, inert gases, and purge gases used to generate the plasma 41 for substrate processing and cleaning gases used to generate the plasma 41 for cleaning the processing chamber 28. The gas delivery system 56 comprises a gas metering system 58 including valves and mass flow controllers (MFCs) to supply the various gases from the gas sources 57 to the processing chamber 28. The gas delivery system 56 comprises a manifold 59 through which the various gases are supplied to the processing chamber 28. A gas injector 63 may be arranged at a center of the dielectric window 24 to inject gases from the manifold 59 into the processing chamber 28. Additionally or alternatively, the gases may be injected from the side of the processing chamber 28.

[0061] During substrate processing, a process gas is supplied to the processing chamber 28. The plasma 41 is generated inside of the processing chamber 28 by supplying RF power from the coil driving circuit 11 to the inductive coil 16. The RF power ignites the process gas to generate the plasma 41. The plasma 41 etches an exposed surface of the substrate 34. An RF source 50, a pulsing circuit 51 , and a bias matching circuit 52 may be used to bias the substrate support 30 during processing to control ion energy. During chamber cleaning, a cleaning gas is supplied to the processing chamber 28. The RF power ignites the cleaning gas to generate the plasma 41 . The plasma 41 is generated inside of the processing chamber 28 by supplying RF power from the coil driving circuit 11 to the inductive coil 16. The plasma 41 generated using the cleaning gas (called the cleaning plasma) cleans various components of the processing chamber 28.

[0062] A temperature controller 64 is connected to the heaters 35 and controls the heaters 35 to control a temperature of the substrate support 30 and the substrate 34. The substrate support 30 includes a temperature sensor 31 to sense the temperature of substrate support 30. The temperature controller 64 communicates with the FCS 40 to control fluid flow through the cooling channels 38 to cool the substrate support 30 based on feedback from the temperature sensor 31 .

[0063] An exhaust system 65 includes a valve 66 and pump 67 to control pressure in the processing chamber 28 and/or to remove reactants from the processing chamber 28 by purging or evacuation. A controller 70 (also called system controller) controls the etching process and the cleaning process. The controller 70 controls the components of the substrate processing system 10. For example, the controller 70 monitors system parameters and controls delivery of the gases from the gas delivery system 56; striking, maintaining, and extinguishing the plasma 41 ; supply of the fluid from the FCS 40; control of the heaters 35; removal of reactants from the processing chamber 28; and so on. Additionally, the controller 70 controls various aspects of the coil driving circuit 11 , the RF source 50, the pulsing circuit 51 , and the bias matching circuit 52, and so on.

[0064] FIG. 2 shows another example of a substrate processing system 100 including a processing chamber 102. The processing chamber 102 comprises a substrate support (also called a pedestal) 104 and a showerhead 106. For example, the pedestal 104 can be an electrostatic chuck (ESC). While not shown, the pedestal 104 can also use other type of clamping mechanism such as vacuum clamping, mechanical clamping, etc. The showerhead 106 is connected to a top plate of the processing chamber 102. The substrate processing system 100 may comprise an actuator (not shown) that can move the pedestal 104 vertically up and down relative to the showerhead 106.

[0065] The pedestal 104 comprises a baseplate 108 and a ceramic plate 110 disposed on the baseplate 108. For example, the baseplate 108 is made of a metallic material such as aluminum or an alloy. The ceramic plate 110 comprises clamping electrodes 112 embedded in the ceramic plate 110. The substrate processing system 100 comprises a power supply 113 to supply power to the clamping electrodes 112. The clamping electrodes 112 clamp a substrate 120 to a top surface of the pedestal 104 during processing.

[0066] The ceramic plate 110 comprises one or more heaters 114 embedded in the ceramic plate to heat the substrate 120. The power supply 113 also supplies power to the heaters 114. The baseplate 108 comprises one or more cooling channels 116 to cool the pedestal 104. A coolant supply system 118 supplies a coolant to the cooling channels 116 to regulate the temperature of the pedestal 104. In addition, a coolant flow control system (simply called a flow control system or FCS) 140 is connected between the coolant supply system 118 and the pedestal 104. The FCS 140 is described below in detail with reference to FIGS. 3-8. Briefly, the FCS 140 receives the coolant supplied by the coolant supply system 118 at a constant flow rate. The FCS 140 supplies the coolant to the cooling channels 116 at flow rates that can be different than the constant flow rate at which the coolant is supplied by the coolant supply system 118.

[0067] The showerhead 106 supplies one or more gases, gas mixtures, and vaporized precursors into the processing chamber 102. For example, the gases comprise process gases, gas mixtures, vaporized precursors, purge gases, cleaning gases, and so on. While not shown, the showerhead 106 may also comprise one or more heaters and one or more cooling channels that receive the coolant from the coolant supply system 118 to regulate the temperature of the showerhead 106.

[0068] The pedestal 104 and the showerhead 106 may also comprise respective temperature sensors 122, 124. A system controller 150 of the substrate processing system 100 receives the temperatures of the pedestal 104 and the showerhead 106 sensed by the temperature sensors 122, 124, respectively. Based on the sensed temperatures, the system controller 150 controls the coolant supply system 118, the FCS 140, the heaters 114 in the pedestal 104, and the heaters in the showerhead 106 to regulate the temperatures of the pedestal 104 and the showerhead 106.

[0069] The substrate processing system 100 comprises a gas delivery system 130, a vapor delivery system 132, and a manifold 134. The gas delivery system 130 comprises a plurality of gas sources, valves, and mass flow controllers (MFCs) (all not shown) to supply various gases and gas mixtures at various flow rates. The gas delivery system 130 supplies the various gases and gas mixtures to the manifold 134. For example, the various gases comprise process gases, purge gases, cleaning gases, and so on. The vapor delivery system 132 supplies one or more vaporized precursors to the manifold 134. The manifold 134 is connected to the gas delivery system 130, the vapor delivery system 132, and the showerhead 106. The showerhead 106 receives one or more gases, gas mixtures, and vaporized precursors from the manifold 134 and supplies them into the processing chamber 102.

[0070] The substrate processing system 100 comprises a radio frequency (RF) power supply 136. For example, the RF power supply 136 supplies RF power to the showerhead 106. When one or more gases are supplied through the showerhead 106 into the processing chamber 102, the RF power supplied to the showerhead 106 strikes a plasma 141 between the showerhead 106 and the pedestal 104.

[0071] The substrate processing system 100 comprises a valve 144 and a pump 146. The pump 146 is connected to the processing chamber 102 through the valve 144. The pump 146 is connected to an exhaust system (not shown) of the substrate processing system 100. The pump 146 maintains pressure (e.g., vacuum) in the processing chamber 102. When vacuum clamping is used, the pump 146 can also be coupled to the pedestal 104 to clamp the substrate 120 using vacuum. The pump 146 also evacuates residual gases and reactants from the processing chamber 102 into the exhaust system of the substrate processing system 100.

[0072] The substrate processing system 100 comprises the system controller 150. The system controller 150 controls all of the components and systems of the substrate processing system 100 described above. For example, the system controller 150 controls the gas delivery system 130, the vapor delivery system 132, the RF power supply 136, the coolant supply system 118, the FCS 140, the heaters 114, the valve 144 and the pump 146, and so on.

FLOW CONTROL SYSTEM AND METHOD

[0073] FIG. 3 shows a general block diagram of the coolant flow control system 200 (e.g., the FCS 40, 140 shown and described with reference to FIGS. 1 and 2). Hereinafter, the coolant flow control system 200 is called the FCS 200 and is similar to the FCS 40, 140 shown and described with reference to FIGS. 1 and 2. The FCS 200 is shown and described generally with reference to FIGS. 3 and 4. Examples of the FCS 200 are shown and described below in detail with reference to FIGS. 5 and 7. Throughout the following description of FIGS. 3-8, while not shown, a substrate similar to the substrates 34, 120 is presume to be present and arranged on a substrate support 204 as shown and described with reference to FIGS. 1 and 2.

[0074] In FIG. 3, the FCS 200 is connected to a coolant supply system 202, which is similar to the coolant supply systems 39, 118 shown and described with reference to FIGS. 1 and 2. The FCS 200 is connected to the substrate support 204, which is similar to the substrate supports 30, 104 shown and described with reference to FIGS. 1 and 2. The FCS 200 is external to the coolant supply system 202 and is interposed between the coolant supply system 202 and the substrate support 204. The coolant supply system 202 supplies a coolant to the FCS 200 at a constant flow rate. The FCS 200 supplies the coolant to one or more cooling channels 206 disposed in the substrate support 204, which are similar to the cooling channels 38, 116 shown and described with reference to FIGS. 1 and 2. The FCS 200 changes the flow rate of the coolant flowing through the substrate support 204 as described below in detail.

[0075] The substrate support 204 comprises one or more heaters (e.g., inner and outer heaters described above) 208, which are similar to the heaters 35, 112 shown and described with reference to FIGS. 1 and 2. The heaters 208 heat the substrate support 204 during the pre-heating stage and during substrate processing as described below in detail. The substrate support 204 comprises a temperature sensor 210, which is similar to the temperature sensors 31 , 124 shown and described with reference to FIGS. 1 and 2. The temperature sensor 210 senses the temperature of the substrate support 200 during the pre-heating stage and during the substrate processing.

[0076] A power supply 212 supplies power to the heaters 208 and is similar to the power supplies 43, 113 shown and described with reference to FIGS. 1 and 2. The power supply 212 supplies power to the heaters 208 during the pre-heating stage and during the substrate processing as described below in detail. A system controller 214 controls the coolant supply system 202, the FCS 200, and the power supply 212. The system controller 214 is similar to the system controllers 64, 150 shown and described with reference to FIGS. 1 and 2. The system controller 214 controls the duty cycle of the heaters 208 by controlling the power supply 212 during the pre-heating stage and during the substrate processing. The system controller 214 controls the flow rate of the coolant through the cooling channels 206 by controlling the FCS 200 during the preheating stage and during the substrate processing as described below in detail. [0077] FIG. 4 shows a method 250 of controlling the temperature of the substrate support 204 using the FCS 200. For example, the system controller 214 performs the method 250 using the power supply 212 and the FCS 200. The system controller 214 performs the following operations based on factors including the temperature of the substrate support 204 sensed by the temperature sensor 210 and based on the process temperature as described below in detail.

[0078] At 252, at the start of the pre-heating stage, the coolant supply system 202 supplies the coolant to the FCS 200 at a constant flow rate and temperature. At 254, the FCS 200 receives the coolant from the coolant supply system 202 and supplies the coolant to the cooling channels 206 in the substrate support 204. Specifically, the FCS 200 decreases the flow rate of the coolant supplied to the cooling channels 206. For example, the FCS 200 receives the coolant from the coolant supply system 202 at a first flow rate and supplies the coolant to the cooling channels 206 in the substrate support 204 at a second flow rate. The first flow rate is the constant flow rate at which the coolant supply system 202 is designed to supply the coolant. The second flow rate at which the FCS 200 supplies the coolant to the cooling channels 206 in the substrate support 204 is less than the first flow rate.

[0079] At 256, the power supply 212 supplies power to the heaters 208 in the substrate support 204 at a duty cycle. The duty cycle is selected such that the temperature differential between the temperature of the coolant flowing through the cooling channels 206 and the temperature of the heaters 208 is less than or equal to a predetermined threshold to prevent thermal shock to the components of the substrate support 204.

[0080] For example, the system controller 214 controls (selects) the duty cycle of the heaters 208 by controlling the power supplied by the power supply 212 to the heaters 208. The system controller 214 controls (selects) the duty cycle of the heaters 208 based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the target temperature of the substrate required by the process to be performed on the substrate, and the flow rate at which the coolant flows through the cooling channels 206.

[0081] At 258, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate has reached the target temperature required by the process to be performed on the substrate. If the temperature of the substrate has not yet reached the target temperature, at 260, the system controller 214 increases the duty cycle at which the power supply 212 supplies power to the heaters 208 and decreases the flow rate at which the FCS 200 supplies the coolant to the cooling channels 206. The method 250 returns to 258.

[0082] If the temperature of the substrate has reached the target temperature, the preheating stage is complete; and at 262, the system controller 214 turns on plasma to process the substrate. For example, the system controller 214 supplies the process gases to the processing chamber and turns on the RF power supply to activate the process gases and ignite plasma as described above with reference to FIGS. 1 and 2.

[0083] At 264, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate has increased to more than the target temperature by heating due to the plasma. The method 250 proceeds to 268 if the temperature of the substrate has not yet increased to more than the target temperature. If the temperature of the substrate has increased to more than the target temperature, at 266, the system controller 214 decreases the duty cycle at which the power supply 212 supplies power to the heaters 208 and increases the flow rate at which the FCS 200 supplies the coolant to the cooling channels 206.

[0084] At 268, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate is equal to the target temperature. If the temperature of the substrate is not equal to the target temperature, the method returns to 266. If the temperature of the substrate is equal to the target temperature, at 270, the system controller 214 determines whether the processing of the substrate is completed. The method 250 returns to 264 if the processing of the substrate is not yet completed. The method 250 ends if the processing of the substrate is completed.

EXAMPLES OF FLOW CONTROL SYSTEM

[0085] Two examples of implementing the FCS 200 and respective methods of controlling the temperature of the substrate support 204 are shown and described with reference to FIGS. 5-8. A first example of the FCS 200 (called FCS 200-1 ) is shown and described with reference to FIGS. 5 and 6. A second example of the FCS 200 (called FCS 200-2) is shown and described with reference to FIGS. 7 and 8. [0086] FIG. 5 shows the FCS 200-1. The FCS 200-1 is external to the coolant supply system 202. The FCS 200-1 is interposed between the coolant supply system 202 and the substrate support 204. The FCS 200-1 comprises a bypass flow control valve 220 and a flow meter 222. The power supply 212 is connected to the heaters 208; and the power supply 212, the temperature sensor 210, and the coolant supply system 202 are connected to the system controller 214 as shown and as described with reference to FIG. 3 above. Additionally, the system controller 214 is connected to the bypass flow control valve 220 and the flow meter 222 of the FCS 200-1 .

[0087] The thicker lines show conduits (piping) through which the coolant flows in the directions shown. The bypass flow control valve (hereinafter the bypass valve) 220 is a 3-port valve. For example, first, second, and third ports of the bypass valve 220 are identified as 1 , 2, and 3, respectively. According to some embodiments, the coolant supply system 202 supplies the coolant at a constant flow rate and temperature to the bypass valve 220. The coolant supply system 202 supplies the coolant through an output of the coolant supply system 202. The output of the coolant supply system 202 is connected to the first port of the bypass valve 220. The second port of the bypass valve 220 is connected to an input of the cooling channels 206. An output of the cooling channels 206 is connected to an input of the coolant supply system 202. The third port of the bypass valve 220 is connected an input of the flow meter 222. An output of the flow meter 222 is connected to (i.e., taps into) the conduit that connects the output of the cooling channels 206 to the input of the coolant supply system 202. The output of the flow meter 222 is downstream from the output of the cooling channels 206 and upstream from the input of the coolant supply system 202.

[0088] The first port of the bypass valve 220 receives the coolant from the coolant supply system 202 at the constant flow rate and temperature. The bypass valve 220 is configured to supply a portion of the received coolant to the cooling channels 206 through the second port. The bypass valve 220 is configured to bypass a portion of the received coolant to the flow meter 222 through the third port. For simplicity, the portion of the coolant bypassed by the bypass valve 220 through the third port is called the bypassed coolant. The flow meter 222 measures the flow rate of the bypassed coolant. The flow meter 222 sends the flow rate of the bypassed coolant to the system controller 214. The system controller 214 can determine the amounts of the coolant to supply to the cooling channels 206 and to bypass through the bypass valve 220 partly based on the flow rate of the bypassed coolant as described below in detail. [0089] A temperature sensor 215 is installed on the conduit that connects the outlet of the coolant supply 202 to the first port of the bypass valve 220. The temperature sensor 215 measures the temperature of coolant supplied by the coolant supply system 202 from the outlet of the coolant supply system 202 to the first port of the bypass valve 220. The temperature sensor 215 provides the measured temperature of the coolant supplied by the coolant supply system 202 to the system controller 214. The system controller 214 can specify a flow rate and a temperature at which the coolant supply system 202 supplies the coolant for a process. The coolant supply system 202 ensures that the coolant is supplied from the outlet of the coolant supply system 202 at the specified flow rate and the temperature. The coolant supply system 202 maintains the flow rate and the temperature at which the coolant flows from the outlet of the coolant supply system 202. The coolant supply system 202 does not change the flow rate and the temperature of the coolant during the process. The FCS 200-1 , specifically, the bypass valve 220 changes the cooling capacity of the coolant by controlling the amount of the coolant that flows through the cooling channels 206 and the amount of the coolant diverted from flowing through the cooling channels 206. The temperature of the coolant measured by the temperature sensor 215 can be used as a control switch to turn off the process if the coolant supply system 202 does not (e.g., fails to) supply the coolant at the set temperature, or if the measured temperature indicates heat loss between the coolant supply system 202 and the substrate support 204. Thus, the temperature of the coolant measured by the temperature sensor 215 provides an additional check for the coolant supplied by the coolant supply system 202 in the form of the control switch as described above.

[0090] The system controller 214 controls the bypass valve 220 to control a flow rate (e.g., a second flow rate) at which the coolant received at the first port is supplied to the cooling channels 206 through the second port. The system controller 214 controls the second flow rate at which the coolant is supplied to the cooling channels 206 through the second port of the bypass valve 220 based on many factors. For example, the factors include the temperature of the substrate support 204 sensed by the temperature sensor 210, the target temperature of the substrate required by the process to be (or being) performed on the substrate, the duty cycle of the heaters 208, the flow rate of the bypass coolant, and in some instances, the temperature of the coolant. The system controller 214 can increase or decrease the second flow rate in conjunctions with the duty cycle of the heaters 208 by controlling the amount of the coolant bypassed through the third port of the bypass valve 220. These operations of the system controller 214 are described below in further detail.

[0091] FIG. 6 shows a method 300 of controlling the temperature of the substrate support 204 using the FCS 200-1 . For example, the system controller 214 performs the method 300 using the power supply 212 and the FCS 200-1. The system controller 214 performs the following operations based on factors including the temperature of the substrate support 204 sensed by the temperature sensor 210, the flow rate of the bypassed coolant measured by the flow meter 222, and the process temperature as described below in detail.

[0092] At 302, at the start of the pre-heating stage, the coolant supply system 202 supplies the coolant at a constant flow rate and temperature to the first port of the bypass valve 220, which is external to the coolant supply system 202. The system controller 214 controls the bypass valve 220 to supply the coolant through the second port of the bypass valve 220 to the cooling channels 206 in the substrate support 204 as follows.

[0093] At 304, the bypass valve 220 decreases the flow rate of the coolant supplied through the second port of the bypass valve 220 to the cooling channels 206. For example, the bypass valve 220 receives the coolant from the coolant supply system 202 at a first flow rate and supplies the coolant to the cooling channels 206 in the substrate support 204 at a second flow rate. The first flow rate is the constant flow rate at which the coolant supply system 202 is designed to supply the coolant. The second flow rate at which the bypass valve 220 supplies the coolant to the cooling channels 206 in the substrate support 204 is less than the first flow rate.

[0094] Since the flow rate of the coolant to the cooling channels 206 is decreased and since the bypass valve 220 continues to receive the coolant from the coolant supply system 202 at the first flow rate, which is constant, the bypass valve 220 bypasses a portion of the coolant through the third port. The flow meter 222 measures the increased flow rate of the bypassed coolant, which allows the system controller 214 to determine an amount by which the flow rate of the coolant supplied to the cooling channels 206 can be changed (e.g., increased) if and when needed.

[0095] At 306, the power supply 212 supplies power to the heaters 208 in the substrate support 204 at a duty cycle. The duty cycle is selected as described in step 256 of the method 250. The description is therefore not repeated for brevity. [0096] At 308, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate has reached the target temperature required by the process to be performed on the substrate. If the temperature of the substrate has not yet reached the target temperature, at 310, the system controller 214 increases the duty cycle at which the power supply 212 supplies power to the heaters 208 and decreases the flow rate at which the bypass valve 220 supplies the coolant to the cooling channels 206. The system controller 214 decreases the flow rate at which the bypass valve 220 supplies the coolant to the cooling channels 206 and increases the amount of the coolant bypassed. The flow meter 222 measures the increased flow rate of the bypassed coolant, which allows the system controller 214 to determine an amount by which the flow rate of the coolant supplied to the cooling channels 206 can be changed (e.g., increased) if and when needed. The method 300 returns to 308.

[0097] If the temperature of the substrate has reached the target temperature, the preheating stage is complete; and at 312, the system controller 214 turns on plasma to process the substrate as described above. At 314, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate has increased to more than the target temperature by heating due to the plasma. The method 300 proceeds to 318 if the temperature of the substrate has not yet increased to more than the target temperature. If the temperature of the substrate has increased to more than the target temperature, at 316, the system controller 214 decreases the duty cycle at which the power supply 212 supplies power to the heaters 208 and increases the flow rate at which the bypass valve 220 supplies the coolant to the cooling channels 206.

[0098] Since the flow rate of the coolant to the cooling channels 206 is increased and since the bypass valve 220 continues to receive the coolant from the coolant supply system 202 at the first flow rate, which is constant, the bypass valve 220 bypasses less coolant through the third port. The flow meter 222 measures the reduced flow rate of the bypassed coolant, based on which the system controller 214 can determine by what amount the flow rate of the coolant supplied to the cooling channels 206 can be increased.

[0099] At 318, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate is equal to the target temperature. If the temperature of the substrate is not equal to the target temperature, the method returns to 316. If the temperature of the substrate is equal to the target temperature, at 320, the system controller 214 determines whether the processing of the substrate is completed. The method 300 returns to 314 if the processing of the substrate is not yet completed. The method 300 ends if the processing of the substrate is completed.

[0100] FIG. 7 shows the FCS 200-2. The FCS 200-2 is external to the coolant supply system 202. The FCS 200-2 is interposed between the coolant supply system 202 and the substrate support 204. The FCS 200-2 comprises a 2-port valve 240, a flow adjuster 242, and a flow meter 244. The power supply 212 is connected to the heaters 208; and the power supply 212, the temperature sensor 210, and the coolant supply system 202 are connected to the system controller 214 as shown and as described with reference to FIG. 3 above. Additionally, the system controller 214 is connected to the 2-port valve 240, the flow adjuster 242, and the flow meter 244 of the FCS 200-2.

[0101] The thicker lines show conduits (piping) through which the coolant flows in the directions shown. The 2-port valve (hereinafter the bypass valve) 240 has a first port and a second port, which are identified as 1 and 2, respectively. The coolant supply system 202 supplies the coolant at a constant flow rate to the bypass valve 240. The coolant supply system 202 supplies the coolant through an output of the coolant supply system 202. The output of the coolant supply system 202 is connected to the first port of the bypass valve 220 and to an input of the cooling channels 206. Specifically, the first port of the bypass valve 220 is connected to the conduit that connects the output of the coolant supply system 202 to the input of the cooling channels 206. The first port of the bypass valve 220 taps into the conduit that connects the output of the coolant supply system 202 to the input of the cooling channels 206. The bypass valve 240 is downstream from the coolant supply system 202 and upstream from the cooling channels 206.

[0102] An output of the cooling channels 206 is connected to an input of the coolant supply system 202. The second port of the bypass valve 240 is connected to an input of the flow adjuster 242. An output of the adjuster 242 is connected to an input of the flow meter 244. An output of the flow meter 244 is connected to (i.e., taps into) the conduit that connects the output of the cooling channels 206 to the input of the coolant supply system 202. The output of the flow meter 244 is downstream from the output of the cooling channels 206 and upstream from the input of the coolant supply system 202.

[0103] In some embodiments, the bypass valve 240 has two states: open (i.e., turned on) or close (i.e., turned off). The first port of the bypass valve 240 receives the coolant from the coolant supply system 202 at the constant flow rate. When the bypass valve 240 is closed, the input of the cooling channels 206 receives the coolant from the coolant supply system 202 at the constant flow rate (e.g., a first flow rate).

[0104] When the bypass valve 240 is opened, some of the coolant supplied by the coolant supply system 202 is diverted from flowing to the cooling channels 206 and is bypassed through the second port of the bypass valve 240. Accordingly, when the bypass valve 240 is opened, the input of the cooling channels 206 receives the coolant from the coolant supply system 202 at a second flow rate that is less than the constant flow rate (i.e., less than the first flow rate).

[0105] Specifically, when the bypass valve 240 is opened, the second flow rate at which the coolant is supplied to the cooling channels 206 is controlled by controlling the flow adjuster 242. The system controller 214 controls the flow adjuster 242 to vary the second flow rate. The flow adjuster 242 can be any electromechanical device that can gradually obstruct or allow coolant flow. For example, the flow adjuster 242 can be controlled to bypass all of the coolant entering the bypass valve 240 through the first port, a portion (any amount) of the of the coolant entering the bypass valve 240 through the first port, or none of the coolant entering the bypass valve 240 through the first port.

[0106] The flow meter 244 measures the flow rate of the bypassed coolant (i.e., the coolant flowing through the bypass valve 240, the flow adjuster 242, and the flow meter 244) and sends the flow rate of the bypassed coolant to the system controller 214. The system controller 214 varies the second flow rate by controlling the flow adjuster 242 based on many factors. For example, the factors include the temperature of the substrate support 204 sensed by the temperature sensor 210, the target temperature of the substrate required by the process to be (or being) performed on the substrate, the duty cycle of the heaters 208, the flow rate of the bypass coolant measured by the flow meter 244, temperature of the coolant, and so on. The system controller 214 can increase or decrease the second flow rate in conjunction with the duty cycle of the heaters 208 by controlling the amount of the coolant bypassed through bypass valve 240, the flow adjuster 242, and the flow meter 244. These operations of the system controller 214 are described below in further detail.

[0107] A temperature sensor 217 is installed on the conduit that connects the outlet of the coolant supply 202 to the first port of the bypass valve 240 and to the inlet of the cooling channels 206. The temperature sensor 217 measures the temperature of coolant supplied by the coolant supply system 202 from the outlet of the coolant supply system 202 to the first port of the bypass valve 240 and to the inlet of the cooling channels 206. The temperature sensor 217 provides the measured temperature of the coolant supplied by the coolant supply system 202 to the system controller 214. The system controller 214 can specify a flow rate and a temperature at which the coolant supply system 202 supplies the coolant for a process. The coolant supply system 202 ensures that the coolant is supplied from the outlet of the coolant supply system 202 at the specified flow rate and the temperature. The coolant supply system 202 maintains the flow rate and the temperature at which the coolant flows from the outlet of the coolant supply system 202. The coolant supply system 202 does not change the flow rate and the temperature of the coolant during the process. The FCS 200-2, specifically, the bypass valve 240 changes the cooling capacity of the coolant by controlling the amount of the coolant that flows through the cooling channels 206 and the amount of the coolant diverted from flowing through the cooling channels 206. The temperature of the coolant measured by the temperature sensor 217 can be used as a control switch to turn off the process if the coolant supply system 202 does not (e.g., fails to) supply the coolant at the set temperature, or if the measured temperature indicates heat loss between the coolant supply system 202 and the substrate support 204. Thus, the temperature of the coolant measured by the temperature sensor 217 provides an additional check for the coolant supplied by the coolant supply system 202 in the form of the control switch as described above.

[0108] FIG. 8 shows a method 350 of controlling the temperature of the substrate support 204 using the FCS 200-2. For example, the system controller 214 performs the method 350 using the power supply 212 and the FCS 200-2. The system controller 214 performs the following operations based on factors including the temperature of the substrate support 204 sensed by the temperature sensor 210, the flow rate of the bypassed coolant measured by the flow meter 244, and based on the process temperature as described below in detail. [0109] At 352, at the start of the pre-heating stage, the coolant supply system 202 supplies the coolant at a constant flow rate and temperature to the first port of the bypass valve 240 and to the cooling channels 206 in the substrate support 204. The system controller 214 controls the bypass valve 240 and the flow adjuster 242 to control the amount of coolant bypassed through the bypass valve 240 to control the flow rate of the coolant flowing through the cooling channels 206 as follows.

[0110] At 354, the system controller 214 opens the bypass valve 240 to divert some of the coolant from flowing through cooling channels 206 to decrease the flow rate of the coolant through the cooling channels 206. The system controller 214 opens the bypass valve 240 and controls the flow adjuster 242 to control an amount of the coolant diverted (bypassed) from flowing through cooling channels 206.

[0111] For example, the bypass valve 240 and the cooling channels 206 receive the coolant from the coolant supply system 202 at a first flow rate. The first flow rate is the constant flow rate at which the coolant supply system 202 is designed to supply the coolant. By opening the bypass valve 240 and controlling the flow adjuster 242, the bypass valve 220 bypasses some of the coolant through the second port, and the second flow rate at which the coolant flows through the cooling channels 206 is reduced to less than the first flow rate. The flow meter 244 measures the flow rate of the bypassed coolant, which allows the system controller 214 to determine an amount by which the flow rate of the coolant supplied to the cooling channels 206 can be changed (e.g., increased) if and when needed.

[0112] At 356, the power supply 212 supplies power to the heaters 208 in the substrate support 204 at a duty cycle. The duty cycle is selected as described in step 256 of the method 250. The description is therefore not repeated for brevity.

[0113] At 358, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate has reached the target temperature required by the process to be performed on the substrate. If the temperature of the substrate has not yet reached the target temperature, at 360, the system controller 214 increases the duty cycle at which the power supply 212 supplies power to the heaters 208. Additionally, the system controller 214 controls the flow adjuster 242 to increase the amount of the coolant bypassed through the second port of the bypass valve 240 and to decrease the flow rate of the coolant flowing through the cooling channels 206. The flow meter 244 measures the increased flow rate of the bypassed coolant, which allows the system controller 214 to determine an amount by which the flow rate of the coolant supplied to the cooling channels 206 can be changed (e.g., increased) if and when needed. The method 350 returns to 358.

[0114] If the temperature of the substrate has reached the target temperature, the preheating stage is complete; and at 362, the system controller 214 turns on plasma to process the substrate as described above. At 364, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate has increased to more than the target temperature by heating due to the plasma. The method 350 proceeds to 368 if the temperature of the substrate has not yet increased to more than the target temperature. If the temperature of the substrate has increased to more than the target temperature, at 366, the system controller 214 decreases the duty cycle at which the power supply 212 supplies power to the heaters 208. Additionally, the system controller 214 controls the flow adjuster 242 to decrease the amount of the coolant bypassed through the second port of the bypass valve 240 and to increase the flow rate of the coolant flowing through the cooling channels 206.

[0115] Since the flow rate of the coolant to the cooling channels 206 is increased and since the bypass valve 240 continues to receive the coolant from the coolant supply system 202 at the first flow rate, which is constant, the bypass valve 240 bypasses less coolant through the second port. The flow meter 244 measures the reduced flow rate of the bypassed coolant, based on which the system controller 214 can determine by what amount the flow rate of the coolant supplied to the cooling channels 206 can be increased. In other words, the coolant flow rate to the substrate support 204 can be changed dynamically in response to a near real-time temperature detection of the coolant at the input point of the coolant to the substrate support.

[0116] At 368, based on the temperature of the substrate support 204 sensed by the temperature sensor 210, the system controller 214 determines whether the temperature of the substrate is equal to the target temperature. If the temperature of the substrate is not equal to the target temperature, the method returns to 366. If the temperature of the substrate is equal to the target temperature, at 370, the system controller 214 determines whether the processing of the substrate is completed. The method 350 returns to 364 if the processing of the substrate is not yet completed. The method 350 ends if the processing of the substrate is completed.

[0117] Thus, the FCS’s 200, 200-1 , 200-2 (collectively the FCS 200) allows controlling the flow rate of the coolant through the substrate support 204 while allowing the coolant supply system 202 to supply the coolant at the designed constant flow rate. Allowing the coolant supply system 202 to supply the coolant at the designed constant flow rate (i.e., not changing the flow rate of the coolant supply system 202) prevents damage to the coolant supply system 202. Instead of changing the flow rate of the coolant supply system 202, the FCS 200, which is external to the coolant supply system 202 and which is interposed between the coolant supply system 200 and the substrate support 204, changes the flow rate of the coolant through the cooling channels 206 as needed. The FCS 200 reduces the flow rate at which the coolant is supplied to the cooling channels 206 during the pre-heating stage. Reducing the flow rate of the coolant through the cooling channels 206 allows the heaters 208 to be operated at a reduced duty cycle during the pre-heating stage, which saves power consumed by the heaters during the pre-heating stage.

[0118] The combination of the reduced flow rate of the coolant through the cooling channels 206 and the reduced duty cycle of the heaters 208 allows the substrate to be heated to the target temperature during the pre-heating stage while reducing the power consumed by the heaters 208 during the pre-heating stage. The reduced duty cycle of the heaters 208 during the pre-heating stage saves the power consumed by the heaters 208 during the pre-heating stage. Additionally, the reduced duty cycle of the heaters 208 during the pre-heating stage leaves more head room to increase the duty cycle of the heaters 208 if the process requires the substrate to be heated to a higher temperature.

[0119] Subsequently, when plasma is struck to process the substrate, the plasma heats the substrate and the substrate support 204. To maintain the temperature of the substrate at the target temperature, the duty cycle of the heaters 208 in the substrate support 204 can be further reduced and the flow rate of the coolant through the cooling channels 206 can be increased using the FCS 200 without changing the flow rate of the coolant supply system 202. By further reducing the duty cycle of the heaters 208, the power consumed by the heaters 208 is further reduced. Moreover, depending on the temperature requirements of the process performed on the substrate, since there is more head room to increase the duty cycle of the heaters 208, the duty cycle of the heaters 208 can be increased if the process requires the substrate to be heated to a higher temperature. The coolant supply system 202 continues to supply the coolant at the designed constant flow rate throughout the pre-heating stage and during substrate processing using plasma, which prevents damage to the coolant supply system 202.

[0120] Accordingly, the FCS 200 provides a control knob to adjust the temperature of the substrate support 204 using the combination of the duty cycle of the heaters 208 and the adjustable flow rate of the coolant without changing the flow rate of the coolant supply system 202. The control knob can be used throughout the pre-heating stage and during substrate processing using plasma. The FCS 200 not only saves the power consumed by the heaters 208 but also extends the temperature range to which the substrate can be heated without requiring additional power for the heaters 208, which allows performing processes requiring higher temperatures. The FCS 200 also helps extend the life of the coolant supply system 202 since the flow rate of the coolant supply system 202 is not changed. Further, since the duty cycle of the heaters 208 is reduced and the flow rate of the coolant through the cooling channels 206 can be adjusted during pre-heating and substrate processing, the temperature differential between the heaters 208 and the cooling channels 206 in the substrate support 204 is also reduced, which reduces the thermal shock on the substrate support 204.

[0121] The foregoing description is merely illustrative in nature and is not intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims.

[0122] It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the examples is described above as having certain features, any one or more of those features described with respect to any one of the examples of the disclosure can be implemented in and/or combined with features of any of the other examples, even if that combination is not explicitly described. In other words, the described examples are not mutually exclusive, and permutations of one or more examples with one another remain within the scope of this disclosure. [0123] Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0124] In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a substrate support, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate.

[0125] The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing 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 delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.

[0126] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, non-transitory memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The 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).

[0127] Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some examples, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

[0128] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process.

[0129] In some examples, a remote computer (e.g., a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then 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 processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control.

[0130] Thus, as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0131] 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 clean 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 systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.

[0132] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.

Claims

CLAIMS What is claimed is:

1 . A system comprising: a substrate support comprising a cooling channel; a coolant supply configured to supply a coolant; and a flow control system configured to receive the coolant from the coolant supply and to supply the coolant to the cooling channel and to selectively divert a portion of the coolant from flowing to the cooling channel.

2. The system of claim 1 wherein: the coolant supply is configured to supply the coolant at a constant flow rate; and the flow control system is configured to receive the coolant from the coolant supply at the constant flow rate and to supply the coolant to the cooling channel at a selected flow rate that is different than the constant flow rate.

3. The system of claim 1 wherein the flow control system is configured to divert the portion of the coolant from flowing to the cooling channel in response to a selected flow rate at which the flow control system supplies the coolant to the cooling channel being different than a flow rate at which the coolant supply is configured to supply the coolant.

4. The system of claim 1 wherein the flow control system comprises a valve configured to receive the coolant from the coolant supply at a constant flow rate, to supply the coolant to the cooling channel at a selected flow rate, and to divert the portion of the coolant from flowing to the cooling channel.

5. The system of claim 1 wherein the substrate support comprises a heater, the system further comprising a controller configured to control a temperature of the substrate support by one or more of: controlling power supplied to the heater; controlling a flow rate at which the flow control system supplies the coolant to the cooling channel; and controlling the portion of the coolant diverted from flowing to the cooling channel.

6. The system of claim 1 wherein: the cooling channel comprises an inlet and an outlet; the coolant supply comprises and inlet and an outlet; the flow control system comprises a three-port valve; and a first port of the three-port valve is connected to the outlet of the coolant supply, a second port of the three-port valve is connected to the inlet of the cooling channel, and a third port of the three-port valve is coupled to the inlet of the coolant supply.

7. The system of claim 6 wherein: the first port of the three-port valve receives the coolant from the outlet of the coolant supply at a constant flow rate; and the three-port valve is configured to (i) selectively divert a portion of the coolant through the third port of the three-port valve to the inlet of the coolant supply and (ii) supply the coolant through the second port of the three-port valve to the inlet of the cooling channel at a selected flow rate.

8. The system of claim 7 wherein the three-port valve is configured to divert the portion of the coolant from flowing through the second port of the three-port valve to the inlet of the cooling channel in response to the selected flow rate being less than the constant flow rate.

9. The system of claim 7 wherein the substrate support comprises a heater, the system further comprising a controller configured to: control power supplied to the heater; and control the three-port valve to (i) selectively divert the portion of the coolant and (ii) supply the coolant to the inlet of the cooling channel at the selected flow rate to control a temperature of the substrate support.

10. The system of claim 1 wherein: the cooling channel comprises an inlet and an outlet; the coolant supply comprises and inlet and an outlet; the flow control system comprises a two-port valve; and a first port of the two-port valve is connected to the outlet of the coolant supply and to the inlet of the cooling channel, the outlet of the cooling channel is connected to the inlet of the coolant supply, and a second port of the two-port valve is coupled to the outlet of the cooling channel and to the inlet of the coolant supply.

11 . The system of claim 10 wherein the flow control system comprises a flow adjuster and wherein: the flow adjuster comprises an inlet connected to the second port of the two-port valve and comprises an outlet coupled to the outlet of the cooling channel and to the inlet of the coolant supply; the first port of the two-port valve is configured to receive the coolant from the outlet of the coolant supply at a constant flow rate; and the two-port valve and the flow adjuster are configured to (i) selectively divert a portion of the coolant through the second port of the two-port valve and the outlet of the flow adjuster to the inlet of the coolant supply and (ii) supply the coolant to the inlet of the cooling channel at a selected flow rate.

12. The system of claim 11 wherein the two-port valve and the flow adjuster are configured to divert the portion of the coolant from flowing to the inlet of the cooling channel in response to the selected flow rate being less than the constant flow rate.

13. The system of claim 11 wherein the substrate support comprises a heater, the system further comprising a controller configured to: control power supplied to the heater; and control the two-port valve and the flow adjuster to (i) selectively divert the portion of the coolant and (ii) supply the coolant to the inlet of the cooling channel at the selected flow rate to control a temperature of the substrate support.

14. A flow control system comprising: a valve configured to receive coolant fluid from a coolant supply, to supply a first portion of the coolant fluid to a cooling channel in a substrate support, and to selectively divert a second portion of the coolant fluid from flowing to the cooling channel; and a meter configured to collect coolant flow rate information from the valve, and to send the collected coolant flow rate to a controller, wherein the flow control system is configured to divert a portion of the coolant fluid to the coolant supply based on the collected coolant flow rate.

15. The flow control system of claim 14 wherein the valve is a three-port valve, and wherein: a first port of the three-port valve is configured to connect to an outlet of the coolant supply; a second port of the three-port valve is configured to connect to an inlet of a cooling channel of the substrate support; and a third port of the three-port valve is configured to be coupled to an outlet of the cooling channel and to an inlet of the coolant supply.

16. The flow control system of claim 15 wherein: the first port of the three-port valve is configured to receive the coolant fluid from the outlet of the coolant supply at a constant flow rate; and the three-port valve is configured to (i) selectively divert a portion of the coolant fluid through the third port of the three-port valve to the inlet of the coolant supply and (ii) supply the coolant fluid through the second port of the three-port valve to the inlet of the cooling channel at a selected flow rate.

17. The flow control system of claim 16 wherein the three-port valve is configured to divert the portion of the coolant fluid from flowing through the second port of the three- port valve to the inlet of the cooling channel in response to the selected flow rate being different than the constant flow rate.

18. A system comprising the flow control system of claim 16 and further comprising the substrate support, wherein the substrate support comprises a heater, the system further comprising a controller configured to control a temperature of the substrate support by one or more of: controlling power supplied to the heater; and controlling the three-port valve to (i) selectively divert the portion of the coolant fluid and (ii) supply the coolant fluid to the inlet of the cooling channel at the selected flow rate.

19. The flow control system of claim 14 wherein the valve is a two-port valve, and wherein: a first port of the two-port valve is configured to connect to an outlet of the coolant supply and to an inlet of the cooling channel; an outlet of the cooling channel is configured to connect to an inlet of the coolant supply; and a second port of the two-port valve is configured to be coupled to the outlet of the cooling channel and to the inlet of the coolant supply.

20. The flow control system of claim 19 wherein the flow control system comprises a flow adjuster, and wherein: the flow adjuster comprises an inlet configured to connect to the second port of the two-port valve and comprises an outlet configured to be coupled to the outlet of the cooling channel and the inlet of the coolant supply; the first port of the two-port valve is configured to receive the coolant fluid from the outlet of the coolant supply at a constant flow rate; and the two-port valve and the flow adjuster are configured to (i) selectively divert a portion of the coolant fluid through the second port of the two-port valve and the outlet of the flow adjuster to the inlet of the coolant supply and (ii) supply the coolant fluid to the inlet of the cooling channel at a selected flow rate while the coolant supply supplies the coolant fluid at the constant flow rate.

21. The flow control system of claim 20 wherein the two-port valve and the flow adjuster are configured to divert the portion of the coolant fluid from flowing to the inlet of the cooling channel in response to the selected flow rate being less than the constant flow rate.

22. A system comprising the flow control system of claim 20 and further comprising the substrate support, wherein the substrate support comprises a heater, the system further comprising a controller configured to control a temperature of the substrate support by one or more of: controlling power supplied to the heater; and controlling the two-port valve and the flow adjuster to (i) selectively divert the portion of the coolant fluid and (ii) supply the coolant fluid to the inlet of the cooling channel at the selected flow rate.

23. A method of controlling temperature of a substrate support, the method comprising: receiving, at a valve, a coolant from a coolant supply; and controlling the valve to supply a first portion of the coolant to a cooling channel in the substrate support and to selectively divert a second portion of the coolant from flowing to the cooling channel.

24. The method of claim 23 further comprising controlling the temperature of the substrate support by controlling the valve while the coolant supply supplies the coolant at a constant flow rate.

25. The method of claim 23 further comprising controlling the valve to divert the second portion of the coolant from flowing to the cooling channel based on a selected flow rate at which the first portion of the coolant is supplied to the cooling channel in the substrate support while the coolant supply supplies the coolant at a constant flow rate.

26. The method of claim 23 further comprising one or more of: controlling a flow rate of the first portion of the coolant supplied by the valve to the cooling channel; and controlling an amount of the second portion of the coolant diverted by the valve from flowing to the cooling channel.

27. The method of claim 23 further comprising: controlling power supplied to a heater of the substrate support; controlling a flow rate at which the first portion of the coolant is supplied by the valve to the cooling channel in the substrate support; or controlling an amount of the second portion of the coolant diverted by the valve from flowing to the cooling channel.

28. The method of claim 23 further comprising: controlling a selected flow rate at which the first portion of the coolant is supplied by the valve to the cooling channel in the substrate support; or controlling an amount of the second portion of the coolant diverted by the valve from flowing to the cooling channel.

29. The method of claim 23 further comprising: controlling a selected flow rate at which the first portion of the coolant is supplied by the valve to the cooling channel in the substrate support; or controlling power supplied to a heater of the substrate support.