Voltage-regulated semiconductor wafer cooling apparatus and method, and voltage regulation device

Abstract

A semiconductor wafer cooling system and method are disclosed, along with a pressure regulating device for mitigating pressure increases in a semiconductor wafer conditioning loop. The pressure regulating device includes a buffer container with an inlet and an outlet channel; wherein the inlet channel is configured to be in fluid communication with a higher pressure position of the semiconductor wafer conditioning loop during operation, and the outlet channel is configured to be in fluid communication with a lower pressure position during operation. The inlet channel includes a pressure control valve configured to close the inlet channel during normal operation, thereby isolating the buffer container from the higher pressure position of the conditioning loop, and to open the inlet channel in response to a pressure rise within the semiconductor conditioning loop exceeding a predetermined level.

Description

Technical Field

[0001] The technical field of this invention relates to a voltage regulating device for a semiconductor wafer regulating circuit and a semiconductor wafer cooling system including such a voltage regulating device. Background Technology

[0002] With the ever-increasing demand for memory and processing power, there is interest in developing next-generation semiconductor devices. These next-generation devices require new manufacturing processes that rely on tighter control over process variables and a wider range of process variables in terms of temperature and pressure. For example, next-generation semiconductor manufacturing processes for 3D NAND and MRAM require cooling semiconductor wafers to extremely low temperatures during certain process steps. While thermal management of semiconductor wafers is not a new requirement, what has changed is the extremely low temperatures to which the wafers need to be cooled. For some next-generation MRAM processes, the theoretically required wafer temperature is as low as -210°C. For 3D NAND, the required wafer temperature ranges from -85°C to -150°C. These low temperatures pose challenges to the management of fluid pressures within the regulation loops.

[0003] In conventional semiconductor wafer cooling solutions, the chuck is cooled using an auxiliary heat transfer fluid (coolant), which is further cooled by a refrigeration unit (cooler). However, heat transfer fluids that can operate at the low temperatures required for manufacturing next-generation devices are often unavailable. Furthermore, such low temperatures can significantly increase the viscosity of any such regulating fluid, resulting in a corresponding increase in pressure within the regulating loop.

[0004] One way to address this problem is to use a refrigerant (the working fluid within the refrigeration system) to directly cool the wafer chuck, in contrast to using an auxiliary heat transfer fluid. In some cases, this can be a single refrigerant, while in others it can be a mixture of refrigerants. The mixed refrigerant can be a blend of multiple components and is a liquid-vapor mixture capable of absorbing heat from the semiconductor wafer using both the sensible and latent heat of the fluid. However, this approach does lead to a phase change in certain components of the mixed refrigerant within the regulating loop, resulting in an increase in the overall specific volume of the refrigerant mixture and, consequently, an increase in pressure within the regulating loop.

[0005] Many semiconductor wafer chucks and the components (piping, fittings, etc.) associated with their conditioning circuits are designed for relatively low maximum operating pressures. Typically, this value is in the range of 150-200 PSIG (pounds per square inch). With the increasing demand for lower temperatures, it has been recognized that coolant pressures (whether auxiliary heat transfer coolant or mixed refrigerant) can exceed the maximum operating pressure limit of the semiconductor wafer conditioning circuit, which can damage the system.

[0006] The goal is to be able to cool the semiconductor wafer to a lower temperature during processing without damaging the wafer conditioning circuit. Summary of the Invention

[0007] A first aspect provides a pressure regulating device for mitigating pressure increases in a semiconductor wafer conditioning circuit, the device comprising: a buffer container including an inlet and an outlet channel; wherein the inlet channel is configured to be in fluid communication with a higher pressure position of the semiconductor wafer conditioning circuit during operation, and the outlet channel is configured to be in fluid communication with a lower pressure position during operation; the inlet channel includes a pressure control valve configured to close the inlet channel during normal operation, thereby isolating the buffer container from the higher pressure position of the conditioning circuit, and to open the inlet channel in response to a pressure rise in the semiconductor conditioning circuit above a predetermined level.

[0008] The inventors of this invention recognized that with increasing demands for temperature and pressure in semiconductor wafer processing, the risk of pressure spikes in the conditioning fluid used to cool semiconductor wafers increases. Conditioning loops that provide localized cooling to semiconductor wafers may not be suitable for some systems with particularly high operating pressures, which can be problematic. If the conditioning fluid experiences significant pressure spikes, this makes it susceptible to damage, and this can be particularly problematic if there is leakage of the conditioning fluid into the vacuum chamber used to process the semiconductor wafer. In this regard, conditioning loops for cooling wafers typically include multiple channels locally arranged to the wafer to provide the required path for the conditioning fluid. These channels are relatively narrow to provide an increased surface area to volume ratio. The wafer conditioning loop is typically located within a process vacuum chamber, and therefore, it is important that pressure rises do not damage the loop to prevent potential leakage of the conditioning fluid into the vacuum chamber.

[0009] Therefore, it is important to protect the regulating circuit used for cooling semiconductor wafers and, in some cases, heating semiconductor wafers, from increased pressure. With this in mind, the inventors have attempted to provide a pressure regulating device that can be added to a wafer cooling apparatus and provides a pressure buffer or expansion vessel. This buffer vessel has an inlet channel configured to connect to a higher-pressure channel within the cooling apparatus and includes a pressure control valve that is closed during normal operation, isolating the buffer vessel from the semiconductor regulating circuit. However, if the pressure rises above a predetermined level, the pressure control valve opens, allowing regulating fluid to flow through the inlet channel and into the buffer vessel, thereby providing almost immediate pressure relief to the regulating circuit and protecting it from the higher pressure. The buffer vessel also includes an outlet channel connected to a lower-pressure location of the semiconductor wafer regulating circuit, through which fluid in the buffer vessel can be discharged. In this respect, the higher-pressure location is upstream of the lower-pressure location.

[0010] In some embodiments, the pressure regulating system further includes a check valve in the outlet channel for suppressing flow from the regulating circuit through the outlet channel to the buffer container.

[0011] In some cases, it may be advantageous to isolate the outlet passage from the regulating circuit during normal operation, and this can be accomplished with the aid of a check valve, so that if the pressure in the regulating circuit toward the outlet passage rises, this will not increase the pressure in the buffer container.

[0012] In some embodiments, the pressure control valve includes a mechanical valve, and in some embodiments, a mechanically spring-loaded valve.

[0013] While pressure control valves can take many forms, it may be advantageous to use non-electrically mechanical valves such as spring-loaded valves because they will open in response to increased pressure even if the system loses power. This can be advantageous and provide some protection against power failure.

[0014] In some embodiments, the pressure regulating system further includes at least one pressure sensor for sensing the pressure of the regulating fluid and a control circuit system configured to generate a control signal in response to a signal received from the at least one pressure sensor.

[0015] As described above, the pressure regulating system attempts to mitigate pressure rises occurring within the regulating loop, and therefore, it may be advantageous to have one or more pressure sensors to measure the pressure within the regulating loop. In this regard, the pressure sensors can sense the pressure in the regulating fluid passage connected to the regulating loop, where the pressure measured indicates the pressure within the regulating loop itself. A control circuit system can be associated with these pressure sensors and is operable to generate control signals for the control system in response to signals received from these pressure sensors, particularly in response to received signals indicating unexpected or excessive pressure rises.

[0016] In some embodiments, the pressure control valve includes an electrically actuated valve, and the control circuitry is configured to generate a control signal to open the electrically actuated valve in response to an indication from the at least one pressure sensor that a predetermined pressure level has been reached or exceeded.

[0017] Although the pressure control valve may be a mechanical valve, alternatively and / or additionally, it may be an electrically actuated valve that can be controlled by a circuit control system in response to a signal from a pressure sensor.

[0018] In some embodiments, the pressure regulating device may be configured to allow selection of the predetermined pressure at which the pressure control valve opens.

[0019] A particular advantage of the pressure regulating system in this embodiment is that it can be configured to mitigate different pressure increases, thereby adapting a single system to different applications and protecting different regulating loops. In this respect, system protection occurs when the pressure control valve opens, and therefore, assuming the pressure control valve can be configured, for example, by changing the spring load of a spring-loaded valve or by selecting different values ​​within the control circuitry of an electrically actuated system, the system can be adapted to provide pressure relief at different pressure levels, thus adapting it to protect different regulating loops applicable to different operating pressures. Given that this system is a stand-alone pressure regulating system, it can be added to an existing cooling system by installing it between the refrigeration system and the regulating loops. The configurable system allows it to be installed within different refrigeration systems and to protect different regulating loops. It also allows for adaptation when changing the process or altering the safety pressure limits.

[0020] In some embodiments, the inlet channel further includes a second valve comprising an electrically actuated valve configured to close when not energized to isolate the pressure control valve and buffer container from the regulating circuit and to open when energized. The electrically actuated valve is controllable and can close in response to a control signal when energized.

[0021] In some embodiments, it may be advantageous to provide a second valve on the inlet channel that closes when not energized. In certain situations, an isolation buffer container may be important, and this may be particularly true where the pressure-actuated valve is a mechanically spring-loaded valve, whose components may be sensitive to higher temperatures, and therefore, during defrost or baking modes, in the presence of extremely high-temperature refrigerant (approximately 125°C) in the regulating circuit, the ability to isolate the pressure control valve by controlling an electrically actuated valve may be advantageous.

[0022] In some embodiments, the buffer container includes at least one additional inlet channel in fluid communication with a location at a higher pressure than the location in fluid communication with the outlet channel. The at least one additional inlet channel includes an electrically actuated valve that is normally closed when energized and open when not energized. The electrically actuated valve is controllable and can open in response to a control signal when energized.

[0023] In some embodiments, providing an additional inlet passage for the buffer container may be advantageous. This can be used not only to increase the flow to the buffer container in the event of pressure peaks, but also to act as a fail-safe inlet passage in the event of a power outage. In this device, as previously described, the mechanically actuated pressure valve allows operation without power; however, in some embodiments, it can be protected from the effects of higher-temperature regulating fluids by an electrically actuated valve that closes when not powered. This renders the mechanical valve inoperable in the event of a power outage. However, if an additional inlet passage is provided with an electrically actuated valve that closes when powered during normal operation but opens when not powered, this allows the buffer container to provide pressure relief in the event of a power outage, even if the mechanically actuated valve is isolated from the regulating fluid line at this time.

[0024] In some embodiments, the control signal circuitry is configured to generate a control signal to open the electrically actuated valve in the at least one other inlet channel in response to an indication from the at least one pressure sensor that a predetermined pressure level has been reached.

[0025] In addition to providing a pressure relief path in the event of a power loss, the electrically actuated valve can also be controlled by a control circuit system to open in response to a pressure rise, thereby providing an additional path and improving fluid flow to the buffer container, thus providing a system that provides a faster response to pressure rises.

[0026] In some embodiments, the at least one other inlet passage further includes a check valve for suppressing flow from the regulating circuit to the buffer container via the at least one other inlet line.

[0027] The other inlet channels may have check valves to suppress backflow from the buffer container. This can be important in cases where power has been lost and there is a pressure spike when the electrically actuated valve in the second line opens. If the pressure in the buffer container rises to a fairly high level and then the pressure in the regulating circuit begins to drop, it is advantageous that no high-pressure regulating fluid enters the inlet line for backflow, and therefore, check valves can be advantageous.

[0028] In some embodiments, the pressure regulating device includes an inlet line for receiving regulating fluid from a cooling system and supplying the regulating fluid to the wafer regulating loop, and a return line for receiving regulating fluid from the wafer regulating loop and returning the fluid to the cooling system, the inlet channel being connected to the inlet line.

[0029] The pressure regulating device is configured to form a standalone module that can be inserted between a cooling system, located in the basement or auxiliary production floor of a semiconductor manufacturing plant, and a wafer conditioning loop within the processing chamber of the manufacturing plant itself. In this arrangement, an outlet line from the cooling system connects to an inlet line of the pressure regulating device, which then flows to the conditioning loop for cooling the wafer. The pressure regulating device has a return line that receives conditioning fluid from the wafer conditioning loop and returns the conditioning fluid to the cooling system for recooling. The inlet line will be a higher-pressure line, and the outlet line will be a lower-pressure line. An inlet channel on a buffer container can be connected to the inlet line, and in some embodiments, the outlet channel is connected to the return line.

[0030] The outlet channel connects to a lower-pressure location, which is advantageously a return line after the semiconductor conditioning loop. If the pressure in this line is significantly lower than the pressure in the inlet line supplying the conditioning fluid to the semiconductor conditioning loop, this allows the buffer container to be effectively emptied. The semiconductor conditioning loop has a smaller channel to facilitate heat transfer, and therefore a considerable pressure drop exists across this loop. In effect, when the pressure control valve is open, the inlet channel, buffer container, and outlet channel provide a bypass route for the conditioning fluid, allowing the conditioning fluid to bypass the wafer conditioning loop and thus protecting the wafer conditioning loop from the higher-pressure conditioning fluid.

[0031] It should be noted that the at least one other inlet channel is typically connected to the inlet line of the pressure regulating device. However, in some cases, it may be connected to the outlet line upstream of the point where the buffer container's outlet channel is connected.

[0032] In some embodiments, the pressure regulating device includes electrically actuated valves on the inlet and return lines for isolating the pressure regulating device and the wafer regulation circuit from the cooling system, wherein the system inlet and outlet electrically actuated valves open when energized and close when not energized.

[0033] To further protect the semiconductor conditioning circuit, it may be advantageous to have electrically actuated system inlet and outlet valves that isolate the voltage regulation system, and effectively the semiconductor wafer conditioning circuit, from the cooling system. Specifically, these electrically actuated valves, configured to close when not powered, automatically isolate the semiconductor wafer conditioning circuit from the cooling system in the event of a power failure. It should be noted that a power failure would cause the entire semiconductor process to stop, and thus isolate the system from the refrigerant to protect the semiconductor circuit from any pressure rise that may occur under such conditions.

[0034] In some embodiments, the control circuitry is configured to close the system inlet valve in response to the sensed pressure rising above another predetermined level above the predetermined level.

[0035] The embodiments not only isolate the system in the presence of power loss, but also in response to a pressure rise exceeding other predetermined levels. In this regard, a valve providing access to a buffer container mitigates rises exceeding a first predetermined level. However, if the pressure continues to rise above another level, it may be advantageous to at least temporarily isolate the pressure regulator and regulating loop from the refrigeration system, and thus the system inlet valve may be configured to close in response to a specific pressure increase.

[0036] In some embodiments, the control circuitry is configured to close the system outlet valve in response to the sensed pressure rising to another higher predetermined level.

[0037] If the pressure does not drop when the system inlet valve is closed, the system outlet valve can also be closed, and the entire system can be shut down.

[0038] In some embodiments, the system may, under any circumstances, choose to close the outlet valve at a predetermined time after closing the inlet valve. The predetermined time allows at least some regulating fluid to be discharged from the system into the refrigeration system before the outlet valve is closed.

[0039] In some embodiments, the control circuitry is configured to open the system inlet valve in response to a sensed pressure drop.

[0040] It is possible that after the inlet valve is closed, the pressure begins to drop in the regulating loop, and in this case, the control circuit system may reopen the inlet valve, and the system continues to operate.

[0041] While the conditioning fluid may include a single-phase fluid, in some embodiments, the conditioning fluid includes a two-phase fluid mixture.

[0042] This pressure regulating system can provide pressure regulation for various regulating fluids, but it is particularly effective for two-phase regulating fluids, which in many cases can be refrigerants from a refrigeration system, which can be a mixed refrigerant system. Such mixed-phase refrigerants are particularly effective in providing the increasingly low temperatures required in semiconductor processing. However, the presence of a gas and liquid phase equilibrium does mean that pressure changes are more prevalent, as the liquid evaporates and forms gas upon heating, thereby increasing the pressure within the system. Therefore, these mixed-phase or two-phase systems are particularly prone to pressure spikes, and the pressure regulating device of this embodiment is particularly effective in protecting the regulating circuit of a semiconductor wafer cooled by such a system.

[0043] In some embodiments, the buffer container is an expansion container in the form of a tank, having a volume for mitigating pressure rise within the regulating loop. In some embodiments, the buffer container is large enough to accommodate the expansion of the regulating fluid within the device as it is heated from cryogenic operation to room temperature.

[0044] As previously described, the buffer container can protect the system from pressure rises during operation, which may occur, for example, during the evaporation of liquid refrigerant in a mixed-phase system. The device can also effectively protect the system in the event of a power failure. To effectively protect the system in the event of a power failure, the buffer container should be sized to accommodate the expansion volume that the regulating fluid will expand to as it changes from the coldest operating temperature of the wafer regulating circuit to room temperature.

[0045] In some embodiments, the regulating circuit includes multiple regulating circuits arranged in parallel for cooling multiple semiconductor wafers.

[0046] The embodiments are effective not only in protecting a single regulating loop, but also, if properly sized, in cooling multiple regulating loops that are connected in parallel or arranged independently.

[0047] In some embodiments, the at least one pressure sensor includes a plurality of pressure sensors configured to sense pressure within the plurality of regulation loops.

[0048] In cases where a voltage regulating device protects multiple semiconductor circuits, it may be advantageous to have multiple pressure sensors for sensing the pressure in each of the regulating circuits, such that a pressure control valve can open in response to a pressure rise in any of the circuits and be depressurized by a buffer container. In this respect, individual wafers may experience different pressure conditions, and therefore pressure peaks or rises may occur at different times in different circuits.

[0049] In some embodiments, the pressure regulating device includes a heating mechanism for heating the buffer container, and the control circuitry is configured to control the heating mechanism to heat the buffer container in response to at least one of the following: activation of the pressure control valve occurs more frequently than a predetermined frequency; and the temperature of the buffer container drops below a predetermined level and remains below the predetermined temperature for a predetermined time.

[0050] When the pressure regulating device is frequently activated within short time cycles, especially in modes where the setpoint temperature of the refrigerant mixture is low, liquid refrigerant may accumulate in the buffer volume. While some accumulation is acceptable and expected, if excessive refrigerant accumulates, it is preferable to have a device that allows the liquid to evaporate and the refrigerant to return to the cooling system for stable operation.

[0051] A second aspect provides a semiconductor wafer cooling apparatus, which includes a cooling system and a voltage regulating device according to the first aspect.

[0052] In some embodiments, the regulating fluid includes the refrigerant of the refrigeration system.

[0053] While the regulating fluid may be an auxiliary regulating fluid cooled by a heat exchanger in a refrigeration system, in some cases it may be the refrigerant itself flowing through a semiconductor regulating loop. In the latter case, it may be a mixed refrigerant, and therefore pressure peaks are more common, making the provision of a pressure regulating device particularly important.

[0054] A third aspect provides a method for providing pressure protection to a semiconductor wafer conditioning circuit, the method comprising: connecting an inlet channel and an outlet channel of a pressure regulating device according to a first aspect of the invention to the inlet and outlet sides of a semiconductor wafer conditioning circuit connected to a cooling system.

[0055] Other particular and preferred aspects are set forth in the appended independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims, as appropriate and in combinations other than those expressly set forth in the claims.

[0056] When a device feature is described as operable to provide a function, it will be understood that this includes device features that provide the function or are adapted or configured to provide the function. Attached Figure Description

[0057] Embodiments of the invention will now be described further with reference to the accompanying drawings, in which:

[0058] Figure 1 A voltage regulating device according to the first embodiment is schematically shown;

[0059] Figure 2 A voltage regulating device according to the second embodiment is schematically shown;

[0060] Figure 3 A voltage regulating device according to a third embodiment is schematically shown;

[0061] Figure 4 This demonstrates how a device according to one embodiment can reduce pressure rise during operation; and

[0062] Figure 5 This illustrates how a device according to one embodiment can mitigate pressure rise during a power failure. Detailed Implementation

[0063] Before discussing any embodiments in more detail, an overview will be provided first.

[0064] The embodiments provide a mechanism that allows adjustment of pressure within the channels (and associated fluid circuits) of a means for regulating a semiconductor wafer, in some embodiments a semiconductor wafer chuck. A buffer expansion volume is provided along with an alternative flow path for the regulating fluid (liquid, gas, or mixture) to prevent the pressure of the regulating fluid from rising above a predetermined operating pressure limit considered a safe pressure limit, and means are provided for diverting the regulating fluid to the expansion volume.

[0065] When pressure increases, coolant or regulating fluid is transferred to a buffer volume via one or more valves actuated based on fluid pressure. In some embodiments, at least one of these valves is mechanically actuated, such that the mechanism operates even in the event of a power failure. Once normal operating conditions are restored, the mechanism allows coolant to be introduced back into the regulating circuit for continued operation.

[0066] The embodiment dynamically provides buffer / additional volume to the regulating fluid (which may be an auxiliary coolant or a mixed refrigerant fluid) as needed and when required, to help reduce pressure within the regulating loop. As a fundamental thermodynamic principle, for a given mass of fluid, pressure is inversely proportional to volume. Therefore, for a given mass of fluid, increasing the volume available for expansion results in a corresponding decrease in the fluid's pressure. However, in a closed system (where no new mass is added or removed from the system), it is important to control the pathway to the buffer volume to ensure that the buffer volume does not become part of the overall system volume during normal operation. The buffer volume should only function when pressure peaks exceed a predetermined value. This is achieved through a control valve arrangement that responds to fluid pressure.

[0067] Figure 1 A pressure regulating device connected to a regulating loop according to one embodiment is shown. The pressure regulating device is connected to a refrigeration system via system inlet valve 14a and system outlet valve 14b. These inlet and outlet valves are electrically operated and configured such that they open when energized but close when power is lost. System inlet valve 14a is connected to inlet line 20, which supplies regulating fluid to the wafer regulating loop SC-1. Return line 22 takes regulating fluid from regulating loop SC-1 and returns the regulating fluid to the refrigeration system via outlet valve 14b.

[0068] The inlet and outlet valves 14a and 14b of the flow control system can be pneumatically or electromagnetically operated. 13a and 13b show the location where the system connects to the refrigeration section of the cooling unit. In this embodiment, check valves 1 and 11 are present on the inlet and outlet lines to prevent backflow of the regulating fluid along the inlet line 20 back to the refrigeration system or back to the regulating loop on the return line 22.

[0069] In this embodiment, there are multiple pressure sensors or pressure transmitters 2 located at different points within the pressure regulating device, used to sense the pressure of the regulating fluid within the system, which is in turn related to the pressure of the fluid in the regulating loop SC-1. The location and number of pressure transmitters will depend on the system.

[0070] In this embodiment, there are two inlet channels 24 and 26 that connect the inlet line 20 to the buffer volume 7. This buffer volume provides pressure relief for the cooling system and is connected to the inlet line 20 via a pressure control valve.

[0071] In this embodiment, a pressure control valve 6 is present in an inlet line 24. In this embodiment, the pressure control valve 6 is a mechanically spring-actuated valve configured to open in response to a predetermined pressure at its inlet. Also present in this embodiment is a valve 5, which acts as an isolation valve and is an electrically actuated open valve. It will be closed when no power is supplied to it, but will open when energized. Therefore, during normal operation, it will open and allow fluid to pass through it, such that valve 6 will open in response to a pressure rise and provide pressure relief to the regulating circuit SC-1.

[0072] Although valve 5 is not present in the embodiment, having such a valve may be advantageous because it can be used to isolate the buffer volume and / or valve 6 from the rest of the system during pump maintenance. Furthermore, valve 5 can be used to protect valve 6 during baking or defrosting modes in which high-temperature refrigerant, possibly around 125°C, flows through the pipes. Since valve 6 is typically designed for low-temperature temperatures, its internal polymer seals may not be suitable for high temperatures, making it advantageous to protect it from these high-temperature fluids by closing valve 5.

[0073] In this embodiment, the buffer container 7 has a pressure relief valve (PRV), which is a safety valve configured to open in response to an increase in pressure in the buffer volume exceeding a predetermined safety limit. The pressure relief valve is configured to vent gas via a pipeline, allowing the discharged gas to be delivered outside the cleanroom environment.

[0074] In this embodiment, in addition to the first inlet channel 24, there is an additional inlet channel 26 providing passage from the inlet line 20 to the buffer volume 7. The second inlet channel includes an electrically actuated valve 3 and a check valve 4 for preventing backflow of regulating fluid from the buffer volume 7 to the inlet line 20. The electrically actuated valve 3 is a normally open valve that will open when no power is supplied to it, but is normally closed when energized. Therefore, if there is a total power loss, it will be de-energized and open, allowing fluid to enter the buffer volume, and thus providing pressure protection for the system in the event of a power failure. In this embodiment, valve 3 is connected to a system controller 30, which receives signals from various pressure transmitters 2 and provides control signals to one or more of the control valves. The system controller 30 is configured to open the electrically actuated valve 3 in response to detecting a pressure rise exceeding a predetermined level. In this way, pressure relief in the event of a pressure peak can be provided via both inlet channels 24 and 26, which improves fluid flow and provides a faster reduction in pressure peaks.

[0075] In this embodiment, there is an outlet line 28 from the buffer volume 7 to the return line 22. This is used to discharge excess pressure from the buffer volume 7 and, in effect, to provide a bypass path for the regulating fluid to bypass the semiconductor regulating loop SC-1 in the event of increased pressure, and to provide pressure relief for the system. In some embodiments, the outlet passage 28 has a check valve 10 to prevent the regulating fluid from flowing back from the return line 22 to the buffer volume 7.

[0076] It should be noted that, although in Figure 1 The diagram shows a single semiconductor wafer regulating circuit and a single voltage regulator, but in some embodiments, multiple semiconductor wafer regulating circuits may be arranged in series, and in this case, the voltage regulator may be used to mitigate pressure rise in all semiconductor wafer regulating circuits, and / or multiple voltage regulators may be present with their inlets and outlets arranged in series between the cooling system and the regulating circuit to provide increased pressure relief and / or an increased-size buffer container 7 with multiple inlet channels.

[0077] Figure 2 Alternative embodiments are shown, which are similar to Figure 1 However, it is operable to provide pressure protection for multiple semiconductor conditioning loops SC-1 and SC-2 arranged in parallel. Additionally, this embodiment includes an additional inlet channel 27 to the buffer volume 7, which is to provide an additional fluid flow path to increase fluid flow into the buffer volume in response to pressure peaks. Because there are multiple wafer conditioning loops (each of which may experience pressure peaks simultaneously), additional fluid flow may be required, and therefore, greater depressurization may be necessary.

[0078] Figure 3 Another alternative embodiment is shown, wherein one of the inlet channels 26, which provides access to the buffer volume 7 and helps regulate pressure within the wafer regulation loop, is downstream of the regulation loop but upstream of the connection between the outlet line 22 and the outlet channel 28, and is connected to the regulation fluid outlet line 22. This arrangement also provides effective pressure regulation and may be advantageous in terms of the physical arrangement and layout of the regulation loop and the availability of additional space for piping on this side. In this case, it should be noted that while one of the inlet channels is provided on the return line 22, the outlet channel 28 is downstream of this inlet channel.

[0079] The following sections outline the different operating modes of embodiments of the voltage regulating device.

[0080] In normal steady-state operation: The regulating fluid / mixed refrigerant (hereinafter referred to as 'fluid') enters the pressure regulating device at 13a on its way to the regulating circuit directly connected to the chuck. The fluid flows through the semiconductor chuck SC-1 and exits this part of the circuit via connection 13b. The flow path of the fluid is 13a-14a—1—SC-1—11—13b.

[0081] The pressure regulating device is designed to adjust the pressure in the event of either a pressure rise or a peak:

[0082] 1. Peak pressure when the unit is operating and has power.

[0083] 2. Peak pressure under conditions of complete power loss

[0084] Failure Mode 1 - With Power on the Unit: In this mode, normal operation continues until the fluid pressure is maintained at or below 90% of the user-defined operating pressure limit. When the fluid pressure begins to approach the operating pressure limit (90%-93% of the maximum value, also known as the opening pressure), the pressure regulating valve 6 begins to partially open. If the pressure continues to rise, valve 6 fully opens. The fluid is now transferred to the buffer volume, and an additional flow path is opened for the fluid, namely 13a-14a—1—5—6—7—10—11—14b—13b. The buffer volume is an empty pressure vessel maintained at a low pressure. In contrast, the wafer regulating loop within the semiconductor chuck is a series of small conduits through which the fluid flows. Therefore, the pressure drop or flow resistance of the fluid through the buffer volume is much lower than that of the regulating loop. The outlet of the buffer volume is connected to the return side of the regulating loop, which is always at a lower pressure than the supply side. Overall, this arrangement results in more fluid flowing into the buffer volume rather than the regulating loop. As the increased volume available for fluid occupation and the mass flow rate actively transferred to the buffer volume decrease, the total pressure in the fluid loop inside and around the regulating loop or clamp decreases. If the rate of pressure drop detected by pressure transmitter 2 is insufficient, valve 3 opens, thus providing an alternative flow path for fluid to the buffer volume. If the event that initially caused the fluid pressure rise was a one-off / instantaneous event, the pressure in the fluid system will begin to return to normal towards the normal operating range. Once the pressure drops to ~93% of its maximum value, valve 6 closes along with valve 3, thereby isolating the buffer volume from the fluid loop. Since the outlet of the buffer volume is connected to the return side (low-pressure side) of the fluid loop, the fluid already present in the buffer volume is automatically discharged back into the fluid loop.

[0085] If the event causing the pressure spike is not instantaneous / one-off and the pressure continues to rise, the supply valve on fluid regulation loop 14a is closed to ensure that no new mass of fluid is introduced into this section of the fluid regulation loop. The return valve 14b on the loop remains open to discharge as much fluid as possible from the chuck and buffer volume. If the event causing the pressure rise persists after a specified time delay, the system compressor is shut off.

[0086] Failure Mode 2 - In the event of complete power loss: If the chamber loses all power, it should be understood that fluid flow in the regulating circuit will cease (compressor shuts down). As the stagnant fluid heats up, it will expand, resulting in an increase in fluid pressure. This pressure increase may be sufficient to damage the wafer regulating circuit, or in this embodiment, damage the chuck SC-1.

[0087] To protect against this failure mode, the following will occur: Valves 14a and 14b will close, isolating the pressure regulator and wafer control circuit from the rest of the refrigeration system. Valve 3 (normally open) will open. This provides a conduit for fluid to expand into the buffer volume. If the mass flow rate through valve 3 is insufficient and the pressure continues to rise, valve 5 will open once the fluid pressure exceeds its rated reverse flow value (pilot operated valve). Valve 5 is selected to allow reverse flow at a back pressure value less than the setpoint value of valve 6.

[0088] Subsequently, valve 6 responds to the pressure rise, thereby allowing additional flow passage into the buffer volume. This results in a pressure drop in the fluid circuit. To protect against this failure mode, the buffer volume should be large enough to accommodate the total volume increase as the fluid warms from cryogenic to ambient temperature. The required volume can be accurately estimated based on fluid properties, the total internal volume of the fluid regulation circuit, and the internal volume of the clamp. When power is restored and the chamber restarts, valve 3 closes and valve 5 opens. When the pressure drops to ~90% of the setpoint pressure, valve 6 closes. The fluid in the buffer volume is drained to the return side of the fluid regulation circuit, and normal operation of the unit can begin.

[0089] Check valves (items 1, 4, 10, 11) are used to ensure that no fluid flows back into the buffer volume or the supply side of the system under abnormal pressure differential conditions.

[0090] Figure 4This diagram schematically illustrates how the pressure within the system changes when the protection mechanism of the pressure regulator is triggered in fault mode 1. In this example, a pressure increase is forced into the system at 50, and when the pressure rises above a predetermined level of 60, the pressure control valve opens, providing pressure relief radially to the system via a passage to a buffer volume and a bypass passage provided by this buffer volume. Pressure relief is maintained at 70 by keeping this flow path open, and once the forced pressure is removed at 80, the pressure within the system drops, the pressure control valve closes, the buffer volume bypass path is once again isolated from the system, and normal operation resumes at 40.

[0091] Figure 5 This illustrates how the system functions to prevent excessive pressure rise in the event of a power failure (failure mode 2). Initially, upon the occurrence of power loss, there is a sharp pressure increase of 100. At 110, the pressure control mechanism activates, the buffer container is connected to the regulating loop, and the system inlet and outlet valves close. Due to the size of the buffer container, the pressure is maintained at a safe level of 120.

[0092] Depending on the arrangement of the processing chambers and the processing steps (parallel wafer processing versus sequential processing), several embodiments are possible. As an example, in a chamber arrangement where more than one semiconductor chuck is used in parallel for equipment fabrication (each chuck runs the same process on the wafer) and each semiconductor chuck is cooled in parallel by the same process cooler, the following can be adopted: Figure 2 The arrangement in the middle. In this embodiment, the pressure regulation principle remains the same; however, it is proposed to use two or more valve assemblies in parallel to ensure a sufficient mass flow rate of fluid (and reduce the proportional response time of pressure) to accommodate the internal volume of multiple clamps.

[0093] exist Figure 3 In another embodiment, a set of valves that help regulate the pressure inside the fluid regulation loop can be placed downstream of the semiconductor chuck. This arrangement also results in effective pressure regulation and can be achieved based on one or more of the following factors: the pressure drop inside the chuck, the physical arrangement / layout of the chuck regulation loop and piping, and the available space.

[0094] Several other embodiments of the concept are possible, such as using two or more pressure regulating valves 6 in parallel to provide faster response time, greater mass flow rate, and so on. These choices will be determined by specific requirements.

[0095] Pressure regulating valve 6 can operate automatically without valve 5. However, during pump maintenance, when complete isolation of the buffer volume is required or valve 6 needs to be replaced, valve 5 acts as a shut-off isolation valve.

[0096] In some embodiments, the pressure control valve or pressure regulating valve 6 is a "cryogenic energy saver". These valves are typically used on large cryogenic tanks (liquid N2, O2, etc.) to maintain static head. Controlling pressure in dynamic operating environments is a novel application for this type of valve.

[0097] Valves 3 and 5 are actively controlled using a simple electronic controller. This can be the main controller of the cryogenic cooler or an auxiliary dedicated controller 30. The controller reads the pressure value from the pressure transmitter 2 in the assembly and relays the signal to the valves to open or close them.

[0098] The entire assembly may have a pressure relief valve (PRV) set to an appropriate venting pressure (such as the venting pressure shown on the buffer container). A venting line for the pressure relief valve may be present to ensure venting outside the cleanroom.

[0099] In some embodiments, where the pressure regulating device is frequently activated within short time cycles, especially in modes where the setpoint temperature of the refrigerant mixture is low, liquid refrigerant may accumulate in the buffer volume. While some accumulation is permissible and expected, if excessive refrigerant accumulates, it is preferable to have a device for evaporating the liquid and returning the refrigerant to the cooling system for stable operation. The heating may be electric, or hot refrigerant may be introduced into the buffer volume 7 via line 27 by opening valve 5 (see, for example, [link to relevant documentation]). Figure 2 This hot refrigerant mixes with the cold liquid in the buffer volume, causing it to evaporate. After a specified time delay, or by sensing the temperature or pressure inside the buffer container, valve 5 can be closed or the heater disconnected.

[0100] In some embodiments, this heating mechanism is activated in response to the detection of frequent system activation or by a combination of controller logic and one or more temperature sensors. The temperature sensors (thermocouples) may be mounted, for example, on the outer wall of the buffer container. A hot gas / electric heating event can be triggered if more than a certain number of pressure relief events occur within a given time period (which can be specified), and if the surface temperature of the container remains below a specified value after the pressure relief events.

[0101] Alternatively, an electric heater can be provided on / in the tank, and this electric heater can be triggered for a specified time after each pressure relief event, or if the surface temperature of the tank remains below a certain value for a given amount of time regardless of whether a pressure relief event has occurred.

[0102] In summary, the following functions are provided by at least some embodiments:

[0103] 1. The ability to control the pressure in the thermal regulation circuit of a semiconductor wafer over a wide temperature range (from low temperature to ambient temperature and above). In this regard, when heating is required rather than cooling, the refrigerant can be supplied from the refrigeration system to the regulation circuit by passing heated refrigerant through a heat exchanger or by transferring heated refrigerant from a hotter part of the refrigeration system.

[0104] 2. The ability to control the pressure of direct refrigerant cooling and auxiliary fluid cooling systems.

[0105] 3. The ability to dynamically control pressure (not just by using pressure relief valves to release pressure), thereby reducing the need for emergency shutdowns and subsequent maintenance and startup procedures in the event of pressure spikes.

[0106] 4. It has the ability to set a user-configurable setpoint for pressure limits and to use the same device over a wide pressure control range (without physically replacing the valve to change the pressure setpoint).

[0107] 5. The ability to provide high resolution for pressure control setpoints is due to the use of a wide variety of valve numbers and types.

[0108] 6. The ability to ensure repeatable process parameters (due to dynamic control and fine setpoint resolution) is often critical in semiconductor manufacturing.

[0109] A combination of mechanically actuated valves and power-assisted (electric or pneumatic) valves provides solutions for most failure modes.

[0110] One embodiment of the pressure regulating device can be added to an existing device to enhance its operating range in terms of temperature, pressure and safety.

[0111] While illustrative embodiments of the invention have been disclosed in detail herein with reference to the accompanying drawings, it should be understood that the invention is not limited to the precise embodiments described, and that various changes and modifications may be made herein without departing from the scope of the invention as defined by the appended claims and their equivalents.

[0112] Figure Labels

[0113] 1, 4, 10, 11 – Check valves

[0114] 2 – Pressure Transmitter

[0115] 3 – Flow control valve, normally open (on / off), which can be pneumatically or electromagnetically actuated.

[0116] 4 – Check valve

[0117] 5 – Pilot-operated, normally closed flow control valve (on / off), which can be pneumatically or electromagnetically actuated.

[0118] 6 – Pressure regulating valve (mechanically actuated)

[0119] 7 – Buffer volume in the form of a pressure vessel

[0120] 10 – Check valve

[0121] 11 – Check valve

[0122] 12 – Pressure Transmitter

[0123] 13a, 13b – represent connections to the refrigeration system.

[0124] 14a, 14b – System inlet and outlet valves

[0125] 20 - Inlet Piping

[0126] 22 – Return Pipeline

[0127] Entrance passages 24, 26, and 27

[0128] 28 Exit Channel

[0129] 30 System Controller

[0130] 40 Normal operating pressure

[0131] 50. Increased forced pressure

[0132] 60. Pressure control mechanism activated.

[0133] The pressure maintained by 70

[0134] 80. Remove the effects of forced pressure

[0135] Pressure rise during 100 power loss period

[0136] 110 Pressure control mechanism activated

[0137] 120. Pressure is maintained over time.

Claims

1. A voltage regulating device for mitigating pressure increases in a semiconductor wafer conditioning circuit, the voltage regulating device comprising: A buffer container, the buffer container including an inlet channel and an outlet channel; in The inlet channel is configured to be in fluid communication with a higher pressure position of the semiconductor wafer conditioning circuit during operation, and the outlet channel is configured to be in fluid communication with a lower pressure position of the semiconductor wafer conditioning circuit during operation. The inlet channel includes at least one pressure control valve configured to close the inlet channel during normal operation, thereby isolating the buffer container from the higher pressure position of the semiconductor wafer conditioning circuit and opening the inlet channel in response to the pressure within the semiconductor wafer conditioning circuit rising above a predetermined pressure level.

2. The pressure regulating device according to claim 1, further comprising a check valve in the outlet channel for suppressing flow from the semiconductor wafer regulating circuit through the outlet channel to the buffer container.

3. The pressure regulating device according to claim 1 or 2, wherein the pressure control valve comprises a mechanically spring-loaded valve.

4. The pressure regulating device according to claim 1 or 2, wherein the pressure regulating device further comprises at least one pressure sensor for sensing the pressure of the regulating fluid and a control circuit system configured to generate a control signal in response to a signal received from the at least one pressure sensor.

5. The pressure regulating device according to claim 4, wherein the pressure control valve includes an electrically actuated valve, and the control circuit system is configured to generate a control signal to open the electrically actuated valve in response to the at least one pressure sensor indicating that a predetermined pressure level has been reached.

6. The pressure regulating device according to claim 3, wherein the pressure regulating device can be configured to allow selection of the predetermined pressure level when the pressure control valve is open.

7. The pressure regulating device according to claim 1 or 2, wherein the inlet channel further includes a second valve, the second valve including an electrically actuated valve configured to close when not energized to isolate the pressure control valve and the buffer container from the semiconductor wafer regulation circuit and to open when energized.

8. The pressure regulating device of claim 4, wherein the buffer container includes at least one other inlet channel in fluid communication with a location at a higher pressure than the location in fluid communication with the outlet channel, the at least one other inlet channel including an electrically actuated valve that is closed when energized and open when not energized.

9. The pressure regulating device according to claim 8, wherein the control circuit system is configured to generate a control signal to open the electrically actuated valve in the at least one other inlet channel in response to an indication from the at least one pressure sensor that a predetermined pressure level has been reached.

10. The pressure regulating device according to claim 8 or 9, wherein the at least one other inlet channel further comprises a check valve for suppressing flow from the semiconductor wafer regulating circuit through the at least one other inlet line to the buffer container.

11. The pressure regulating device of claim 4, wherein the pressure regulating device includes an inlet line for receiving regulating fluid from a cooling system and for supplying the regulating fluid to the semiconductor wafer regulating circuit, and a return line for receiving regulating fluid from the semiconductor wafer regulating circuit and returning the regulating fluid to the cooling system, the inlet channel being connected to the inlet line.

12. The pressure regulating device according to claim 11, wherein the outlet channel is connected to the return line.

13. The pressure regulating device according to claim 11 or 12, wherein the pressure regulating device includes an electrically actuated valve on the inlet line and an electrically actuated valve on the return line for isolating the pressure regulating device and the semiconductor wafer regulation circuit from the cooling system, wherein the electrically actuated valve on the inlet line and the electrically actuated valve on the return line are open when energized and closed when not energized.

14. The pressure regulating device of claim 13, wherein the control circuitry is configured to close the electrically actuated valve on the inlet line in response to a sensed pressure rising above another predetermined pressure level higher than the predetermined pressure level.

15. The pressure regulating device of claim 14, wherein the control circuitry is configured to close the electrically actuated valve on the return line in response to the sensed pressure rising to a higher, other predetermined pressure level.

16. The voltage regulating device of claim 14, wherein the control circuit system is configured to close the electrically actuated valve on the return line after a predetermined time.

17. The pressure regulating device of claim 13, wherein the control circuitry is configured to open the electrically actuated valve on the inlet line in response to a sensed pressure drop.

18. The voltage regulating device according to claim 1 or 2, wherein the regulating fluid used in the semiconductor wafer regulating circuit comprises a two-phase fluid mixture.

19. The pressure regulating device according to claim 1 or 2, wherein the size of the buffer container is sufficient to accommodate the expansion of the regulating fluid within the device as it is heated from cryogenic operation to room temperature.

20. The voltage regulating device according to claim 4, wherein the semiconductor wafer regulating circuit comprises a plurality of regulating circuits arranged in parallel for cooling a plurality of semiconductor wafers.

21. The pressure regulating device of claim 20, wherein the at least one pressure sensor comprises a plurality of pressure sensors configured to sense pressure within the plurality of regulating loops.

22. The pressure regulating device according to any one of claims 5, 8 to 9, 11 to 12, 14 to 17, and 20 to 21, wherein the pressure regulating device includes a heating mechanism for heating the buffer container, and the control circuitry is configured to control the heating mechanism to heat the buffer container in response to at least one of the following: The activation of the pressure control valve occurs more frequently than a predetermined frequency; and The temperature of the buffer container drops below a predetermined temperature and remains below the predetermined temperature for a predetermined time.

23. The pressure regulating device according to claim 1 or 2, wherein the buffer container includes at least one other inlet channel in fluid communication with a location at a higher pressure than the location in fluid communication with the outlet channel, the at least one other inlet channel including an electrically actuated valve that is closed when energized and open when not energized.

24. The pressure regulating device according to claim 1 or 2, wherein the pressure regulating device includes an inlet line for receiving regulating fluid from the cooling system and for supplying the regulating fluid to the semiconductor wafer regulating circuit, and a return line for receiving regulating fluid from the semiconductor wafer regulating circuit and returning the regulating fluid to the cooling system, the inlet channel being connected to the inlet line.

25. The voltage regulating device according to claim 1 or 2, wherein the semiconductor wafer regulating circuit comprises a plurality of regulating circuits arranged in parallel for cooling a plurality of semiconductor wafers.

26. The pressure regulating device of claim 5, wherein the pressure regulating device may be configured to allow selection of the predetermined pressure level when the electrically actuated valve is opened.

27. A semiconductor wafer cooling apparatus comprising a cooling system and a voltage regulating device according to any one of claims 1 to 26.

28. The semiconductor wafer cooling apparatus of claim 27, wherein the regulating fluid used in the semiconductor wafer regulating circuit comprises the refrigerant of the cooling system.

29. A method for providing pressure protection to a semiconductor wafer conditioning circuit, the method comprising: The inlet and outlet channels of the voltage regulating device according to any one of claims 1 to 26 are connected to the semiconductor wafer regulating circuit such that they are in fluid communication with the inlet and outlet channels of the semiconductor wafer regulating circuit, and these channels are configured to receive regulating fluid from the cooling system and to return the regulating fluid to the cooling system.

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