Pressure-adjusting semiconductor wafer cooling device and method, and pressure adjustment device

Abstract

A semiconductor wafer cooling system and method, and a pressure regulator for mitigating pressure buildup in a semiconductor wafer conditioning circuit, are disclosed. The pressure regulator comprises a buffer vessel including an inlet channel and an outlet channel, the inlet channel configured to be in fluid communication with a higher pressure location of the semiconductor wafer conditioning circuit during operation, the outlet channel configured to be in fluid communication with a lower pressure location of the semiconductor wafer conditioning circuit during operation, and the inlet channel includes a pressure control valve configured to close the inlet channel so that the buffer vessel is isolated from the higher pressure location of the conditioning circuit during normal operation, and to open the inlet channel in response to pressure in the semiconductor wafer conditioning circuit exceeding a predetermined level.

Description

Technical Field

[0001] The field of the present invention relates to a pressure regulating device for a semiconductor wafer conditioning circuit and a semiconductor wafer cooling system including such a pressure regulating device.

Background Art

[0002] As the demand for memory and processing power continues to increase, there is interest in the development of next-generation semiconductor devices. Such next-generation devices require more precise control of process variables, as well as new manufacturing processes that rely on a wider process variable envelope for temperature and pressure. For example, in the next-generation semiconductor manufacturing processes of 3D NAND and MRAM, it is necessary to cool the semiconductor wafer to extremely low temperatures during some process steps. Thermal management of semiconductor wafers is not a new requirement, but what has changed is the low temperature at which the wafer needs to be cooled. In some next-generation MRAM processes, the theoretically required wafer temperature is as low as about -210°C. In 3D NAND, the required wafer temperature is -85°C to -150°C. At these low temperatures, the management of fluid pressure within the conditioning circuit becomes an issue.

[0003] In conventional semiconductor wafer cooling solutions, a chuck is cooled using a secondary heat transfer fluid (coolant) cooled using a cooling unit (chiller). However, heat transfer fluids that can function at the low temperatures required for the manufacture of next-generation devices are generally not available. Furthermore, at such low temperatures, the viscosity of any such conditioning fluid can increase significantly, which may cause the pressure within the conditioning circuit to rise accordingly.

[0004] One way to address this problem is to directly cool the wafer chuck using the refrigerant, which is the working fluid within the cooling system, as opposed to using a secondary heat transfer fluid. This refrigerant can be a single refrigerant or a mixed refrigerant. A mixed refrigerant is a blend of multiple components and can be a liquid-vapor mixture that utilizes both the sensible and latent heat of the fluid to absorb heat from the semiconductor wafer. However, in this approach, specific components of the mixed refrigerant undergo a phase change within the regulating circuit, increasing the overall specific volume of the mixed refrigerant and consequently raising the pressure within the regulating circuit.

[0005] Many semiconductor wafer chucks and associated components (such as piping, connectors, etc.) related to their regulating circuits are rated for a fairly low maximum operating pressure. Typically, this value is within the range of 150 - 200 PSIG (pounds per square inch gauge). Along with the low temperature requirements, it has been found that there is a risk of damaging the system if the coolant pressure exceeds the maximum operating pressure limit of the semiconductor wafer regulating circuit, whether the secondary coolant or a mixed refrigerant is used.

Summary of the Invention

Problems to be Solved by the Invention

[0006] It would be desirable to be able to cool the semiconductor wafer to a low temperature without damaging the wafer regulating circuit during the processing operation.

Means for Solving the Problems

[0007] A first aspect provides a pressure regulating device for alleviating a pressure increase within a semiconductor wafer conditioning circuit, the device comprising a buffer vessel including an inlet channel and an outlet channel, the inlet channel being configured to be in fluid communication with a high-pressure location of the semiconductor wafer conditioning circuit during operation, the outlet channel being configured to be in fluid communication with a low-pressure location during operation, the inlet channel including a pressure control valve configured to close the inlet channel such that the buffer vessel is isolated from the high-pressure location of the conditioning circuit during normal operation and to open the inlet channel in response to the pressure within the semiconductor conditioning circuit exceeding a predetermined level.

[0008] The inventors of the present invention have recognized that as the demand for temperature and pressure in semiconductor wafer processing increases, the risk of pressure spikes in the conditioning flow body used to cool the semiconductor wafer also increases. This can be a problem in some systems where the conditioning circuit, which locally cools the semiconductor wafer, is not rated for particularly high operating pressures. For this reason, these systems are vulnerable to damage when the conditioning fluid is subject to significant pressure spikes, and particularly so when the conditioning fluid leaks into the vacuum chamber used for processing the semiconductor wafer. In this regard, the conditioning circuit for cooling the wafer includes a plurality of channels disposed locally on the wafer that provide the necessary passageways for the conditioning fluid. These channels are relatively narrow channels that increase the surface area-to-volume ratio. The wafer conditioning circuit is generally present within a process vacuum chamber, and thus it is important that pressure increases do not damage the circuit and cause the conditioning fluid to leak into the vacuum chamber.

[0009] Therefore, it is important to protect the regulation circuit that cools and possibly heats the semiconductor wafer from a pressure increase. With this in mind, the inventors aim to provide a pressure regulating device that can be added to the wafer cooling device and provides a pressure buffer or expansion vessel. This buffer vessel has an inlet channel configured to connect to the high-pressure channel in the cooling device and is closed during normal operation so that the buffer vessel is isolated from the semiconductor regulation circuit, but opens when the pressure rises above a predetermined level to allow the regulating fluid to flow into the buffer vessel through the inlet channel, including a pressure control valve that provides almost immediate pressure relief to the regulation circuit and protects the regulation circuit from high pressure. The buffer vessel also includes an outlet channel connected to the low-pressure position of the semiconductor wafer regulation circuit to allow the fluid in the buffer vessel to be discharged. In this regard, the high-pressure position is upstream of the low-pressure position.

[0010] In some embodiments, the pressure regulation system further comprises a check valve in the outlet channel that inhibits flow from the regulation circuit to the buffer vessel via the outlet channel.

[0011] In some cases, it is considered advantageous to separate the outlet channel from the regulation circuit during normal operation, and this separation can be achieved using a check valve so that the pressure in the buffer vessel does not increase when the pressure towards the outlet channel of the regulation circuit increases.

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

[0013] The pressure control valve can have multiple forms, but it is considered advantageous to use a non-electric mechanical valve such as a spring-biased valve because it opens in response to an increase in pressure even when power to the system is lost. This is advantageous and can provide some protection from power outages.

[0014] In some embodiments, the pressure regulation system further comprises at least one pressure sensor that senses the pressure of the regulation fluid, and a control circuit configured to generate a control signal in response to a signal received from the at least one pressure sensor.

[0015] As described above, it can be advantageous for the pressure regulation system to have one or more pressure sensors that attempt to mitigate the pressure rise occurring within the regulation circuit and thus measure the pressure within the regulation circuit. In this regard, the pressure sensor can sense the pressure within the regulation fluid channel connected to the regulation circuit, and the pressure measured there indicates the internal pressure of the regulation circuit itself. The control circuit is associated with these pressure sensors and can generate a control signal for controlling the system in response to signals received from these pressure sensors, particularly in response to a received signal indicating an unexpected or overly large pressure rise.

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

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

[0018] In some embodiments, the pressure regulation device can be configured to be able to select the pressure at which the pressure control valve opens.

[0019] One particular advantage of the pressure regulation system of the embodiment is that it can be configured to mitigate the increase in different pressures and make a single system suitable for different applications and the protection of different regulation circuits. In this regard, the protection of the system occurs when the pressure control valve is opened, and thus, if the pressure control valve can be configured, for example, by changing the spring load of a spring-biased valve or by selecting different values in the control circuit of an electrically actuated system, the system can be adapted to perform pressure relief at different pressure levels and be suitable for the protection of different regulation circuits rated for different operating pressures. Considering that this system is a stand-alone pressure regulation system that can be added to an existing cooling system by being installed between the cooling system and the air conditioning circuit, having a configurable system allows this system to be installed in different cooling systems to protect different regulation circuits. Also, this enables the system to be adaptable during process changes or changes in safety pressure limits.

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

[0021] In some embodiments, it may be advantageous to provide a second valve on the inlet channel that closes when power is not supplied. Depending on the situation, it may be important to isolate the buffer container, which is particularly true when the pressure-actuated valve is a mechanical spring-biased valve with components that are vulnerable to high temperatures. Thus, during the defrost mode or bake-out mode in which a super-high temperature refrigerant around 1250 °C may be present in the regulation circuit, it may be advantageous to be able to isolate the pressure control valve by controlling the electrically actuated valve.

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

[0023] In some embodiments, it may be advantageous to provide an additional inlet channel to the buffer vessel. This inlet channel can be used not only to increase the flow rate to the buffer vessel in the case of a pressure spike, but also as a fail-safe inlet channel when power is lost to the device. As described above, in this device, a mechanically actuated pressure valve enables operation without power, but in some embodiments, the device can be protected from a hot conditioning fluid by an electrically actuated valve that closes when power is not supplied. In this embodiment, the mechanical valve becomes inoperative when power is lost. However, if an additional inlet channel with an electrically actuated valve that closes during normal power supply operation and opens when power is not supplied is provided, the buffer vessel can provide pressure relief when power is lost, even if the mechanically actuated valve is separated from the conditioning fluid line at this point.

[0024] In some embodiments, the control signal circuit is configured to generate a control signal for opening the electrically actuated valve in the at least one additional inlet channel in response to the at least one pressure sensor indicating that a predetermined pressure level has been reached.

[0025] In addition to providing a pressure relief channel for when power is lost, the electrically actuated valve can also be controlled by a control circuit to open in response to a pressure increase, thus providing an additional channel, improving the fluid flow to the buffer vessel, and thus providing a system that speeds up the response to a pressure increase.

[0026] In some embodiments, at least one additional inlet channel further includes a check valve that inhibits flow from the regulating circuit to the buffer vessel via the at least one additional inlet conduit.

[0027] The additional inlet channel can have a check valve such that backflow from the buffer vessel is inhibited. This is important when there is a pressure spike when power is lost and the electrically actuated valve in the second conduit is open. If the pressure in the regulating circuit begins to drop after the pressure in the buffer vessel has risen to a fairly high level, it is advantageous if the high-pressure regulating fluid does not flow back into the inlet conduit, and thus the check valve can be advantageous.

[0028] In some embodiments, the pressure regulating device comprises an inlet conduit that receives regulating fluid from a cooling system and supplies the regulating fluid to the wafer regulating circuit, and a return conduit that receives regulating fluid from the wafer regulating circuit and returns the fluid to the cooling system, and the inlet channel is connected to the inlet conduit.

[0029] The pressure regulating device is configured to form an independent module that can be inserted between a cooling system that may be present in the basement or sub-fab of a semiconductor manufacturing facility (fab) and a wafer regulating circuit that is present in the processing chamber of the manufacturing facility itself. In such an arrangement, the outlet conduit from the cooling system is connected to the inlet conduit of the pressure regulating device, which flows to the regulating circuit to cool the wafer, and the pressure regulating device has a return conduit that receives regulating fluid from the wafer regulating circuit and returns it to the cooling system for cooling again. The inlet conduit becomes a high-pressure conduit and the outlet conduit becomes a low-pressure conduit. The inlet channel on the buffer vessel can be connected to the inlet conduit, and in some embodiments the outlet channel is connected to the return conduit.

[0030] The outlet channel is connected to a low-pressure location, which advantageously is the return line after the semiconductor regulating circuit. As a result, when the pressure in this line is significantly lower than the pressure in the inlet line supplying the regulating fluid to a semiconductor regulating circuit having narrow channels to promote heat transfer and thus a significant pressure drop across this circuit, the buffer vessel can be effectively drained. In fact, the inlet channel, the buffer vessel and the outlet channel provide a bypass route for the regulating fluid when the pressure control valve is open, enabling the regulating fluid to bypass the wafer regulating circuit and thus protect the wafer regulating circuit from the high-pressure regulating fluid.

[0031] In addition, at least one further inlet channel is generally connected to the inlet line of the pressure regulating device. However, in some cases, it can also be connected to the outlet line upstream of the point where the outlet channel of the buffer vessel is connected.

[0032] In some embodiments, the pressure regulating device comprises on the inlet line and the return line an electrically actuated valve that separates the pressure regulating device and the wafer regulating circuit from the cooling system, and the system inlet and outlet electrically actuated valves open when power is supplied and close when power is not supplied.

[0033] For further protection of the semiconductor regulating circuit, it can be advantageous to have an electrically actuated system inlet valve and an outlet valve that enable the pressure regulating system, in fact the semiconductor wafer regulating circuit, to be separated from the cooling system. Specifically, these valves are electrically actuated valves configured to close when power is not supplied so that in the event of a power failure the semiconductor wafer regulating circuit is automatically separated from the cooling system. Since the entire semiconductor process stops during a power failure, separating the system from the refrigerant serves to protect the semiconductor circuit from the pressure increase that can occur in this situation.

[0034] In some embodiments, the control circuit is configured to close the system inlet valve in response to the sensed pressure rising above a further predetermined level that is higher than the predetermined level.

[0035] The embodiment can also separate the system in response to a pressure increase above a further predetermined level, similar to separating the system during power loss. In this regard, an increase above the first predetermined level is mitigated using a valve that provides access to the buffer vessel. However, if the pressure continues to rise above a further level, it is considered advantageous to at least temporarily separate the pressure regulating device and the regulating circuit from the cooling system, and thus the system inlet valve can be configured to close in response to a specific pressure increase.

[0036] In some embodiments, the control circuit is configured to close the system outlet valve in response to the sensed pressure rising to a further predetermined level that is even higher.

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

[0038] In some embodiments, the system can choose to close the outlet valve after a predetermined time after closing the inlet valve under any circumstances. This predetermined time allows at least some of the regulating fluid to be discharged from the system to the cooling system before closing the outlet valve.

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

[0040] In some cases, the pressure in the regulating circuit may start to drop after the inlet valve is closed. In such a case, the control circuit can open the inlet valve again so that the system can continue to operate.

[0041] The regulating fluid can include a single-phase fluid, but in some embodiments, the regulating fluid includes a two-phase mixture of fluids.

[0042] This pressure regulation system can provide pressure regulation for different regulation fluids, but is particularly effective for a two-phase regulation fluid that can be refrigerant from a cooling system, which is often a mixed refrigerant system. Such a mixed-phase refrigerant is particularly effective in providing the low temperatures increasingly required in semiconductor processing. However, as a liquid warms, it evaporates to form a gas, increasing the pressure within the system, so the fact that the gas phase and liquid phase exist in an equilibrium state means that pressure changes are large. Therefore, these mixed-phase or two-phase systems are particularly prone to pressure spikes, and the pressure regulation device of the embodiment is particularly effective in protecting the semiconductor wafer regulation circuit 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 alleviating a pressure increase within the regulation circuit. In some embodiments, the size of the buffer container is sufficient to accommodate the expansion of the regulation fluid within the device as it warms from a low operating temperature to room temperature.

[0044] As described above, the buffer container can protect the operating system from pressure increases that may occur, for example, when the liquid refrigerant within a mixed-phase system evaporates. The device is also thought to be effective in protecting the system in the event of a power outage. The buffer container should be sized to accommodate the expansion volume of the regulation fluid as it expands from the lowest operating temperature of the wafer regulation circuit to room temperature in order to effectively protect the system during a power outage.

[0045] In some embodiments, the regulation circuit includes a plurality of regulation circuits arranged in parallel for cooling a plurality of semiconductor wafers.

[0046] The embodiment is not only effective in protecting a single regulation circuit, but can also be used for cooling a plurality of regulation circuits arranged in parallel or alone, in the case of a suitable size.

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

[0048] When the pressure regulating device protects a plurality of semiconductor circuits, it can be advantageous to have a plurality of pressure sensors that sense the pressure within each regulating circuit so that in response to a pressure increase within any of the circuits, the pressure control valve opens and the buffer vessel can provide pressure relief. In this regard, individual wafers may be exposed to different pressure conditions, and thus pressure spikes or increases may occur at different times in different circuits.

[0049] In some embodiments, the pressure regulating device includes a heating mechanism for heating the buffer vessel, and the control circuit is configured to control the heating mechanism to heat the buffer vessel in response to at least one of the pressure control valve actuating more frequently than a predetermined frequency and the temperature of the buffer vessel dropping below a predetermined level and remaining below the predetermined temperature for a predetermined time.

[0050] When the pressure regulating device operates frequently within a short period of time, particularly in a mode where the setpoint temperature of the refrigerant mixture is low, a state may occur where liquid refrigerant accumulates within the buffer vessel. Some accumulation is expected and not a problem, but if excessive refrigerant accumulates, it is preferable to have means to evaporate the liquid and return the refrigerant to the cooling system for stable operation.

[0051] A second aspect provides a semiconductor wafer cooling device including a cooling device and a pressure regulating device according to the first aspect.

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

[0053] The regulating fluid can be a secondary regulating fluid that is cooled using a heat exchanger in the cooling system, but in some cases, it can also be the refrigerant itself flowing through the semiconductor regulating circuit. In the latter case, the regulating fluid can be a mixed refrigerant, and thus pressure spikes are likely to occur, making it particularly important to provide a pressure regulating device.

[0054] A third aspect is a method of pressure protecting a semiconductor wafer regulating circuit, the method including connecting an inlet channel and an outlet channel of a pressure regulating device according to the first aspect of the present invention to an inlet side and an outlet side of a semiconductor wafer regulating circuit connected to a cooling system.

[0055] The appended independent and dependent claims set forth further specific preferred aspects. The features of the dependent claims can be combined with the features of the independent claims as necessary, and can also be in combinations other than those explicitly stated in the claims.

[0056] When describing the features of a device as providing a function, this feature is to be understood as including the features of a device that provides that function, or a device adapted or configured to provide that function.

[0057] Hereinafter, embodiments of the present invention will be further described with reference to the accompanying drawings.

Brief Description of the Drawings

[0058]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0059] Before explaining the embodiments in more detail, an overview will first be described.

[0060] The embodiments provide a mechanism that enables adjustment of the pressure within a channel (and associated fluid circuitry) of an apparatus for conditioning a semiconductor wafer, which in some embodiments is a semiconductor wafer chuck. A buffer expansion volume is provided along with an alternative flow path for the conditioning fluid (liquid, gas, or mixture) in case the pressure of the conditioning fluid rises above a predetermined operating pressure limit that is considered a safe pressure limit, and means are provided for diverting the conditioning fluid into the expansion volume.

[0061] Upon a pressure increase, the coolant or conditioning fluid is diverted into the buffer volume through one or more valves that operate based on the fluid pressure. In some embodiments, at least one of the valves operates mechanically so that the mechanism functions even during a power outage. When normal operating conditions resume, the mechanism enables the coolant to be introduced back into the conditioning circuit for continued operation.

[0062] The embodiments dynamically provide, as needed, a buffer / additional volume for the conditioning fluid, which can be a secondary coolant or a mixed refrigerant fluid, to help with a pressure drop within the conditioning circuit. As a basic thermodynamic principle, for a given mass of fluid, pressure is inversely proportional to volume. Thus, increasing the volume available for expansion of a given mass of fluid causes the pressure of the fluid to decrease correspondingly. However, in a closed system (where no new mass is added to or removed from the system), it is important that access to the buffer volume is controlled to ensure that the buffer volume does not become part of the overall system volume during normal operation. The buffer volume should only come into play in the case of a pressure spike that exceeds a predetermined value. This setting is done through a control valve that reacts to the fluid pressure.

[0063] FIG. 1 shows a pressure regulating device connected to an adjustment circuit according to an embodiment. This pressure regulating device is connected to the cooling system by a system inlet valve 14a and a system outlet valve 14b. These inlet and outlet valves are electric and are configured to open when power is supplied and close when power is lost. The system inlet valve 14a is connected to an inlet conduit 20 that supplies regulated fluid to the wafer adjustment circuit SC-1. A return conduit 22 removes the regulated fluid from the adjustment circuit SC-1 and returns it to the cooling system via the outlet valve 14b.

[0064] The inlet and outlet valves 14a, 14b of the flow control system can be pneumatic or electromagnetic. 13a, 13b indicate where the system is connected to the cooling part of the cooling device. In this embodiment, check valves 1 and 11 are present on the inlet conduit and the outlet conduit to suppress backflow of the regulated fluid along the inlet conduit 20 towards the cooling device or back towards the adjustment circuit on the return conduit 22.

[0065] In this embodiment, there are a plurality of pressure sensors or pressure transducers 2 located at different points within the pressure regulating device that serve to sense the pressure of the regulated fluid within this system, which is also related to the pressure of the fluid within the adjustment circuit SC-1. The position and number of pressure transducers depend on the system.

[0066] In this embodiment, there are two inlet channels 24 and 26 that connect the inlet conduit 20 to a buffer volume 7. This buffer volume provides pressure relief for the cooling system and is connected to the inlet conduit 20 by a pressure control valve.

[0067] In this embodiment, there is a pressure control valve 6, which is a mechanical spring actuated valve configured to open in response to a predetermined pressure at the inlet, within a single inlet pipeline 24. In this embodiment, there is also a valve 5, which functions as a shut-off valve and is an electrically actuated open-type valve that closes in the absence of power and opens when power is supplied. Therefore, during normal operation, when valve 5 opens to allow fluid to pass through, valve 6 opens in response to the increase in pressure to provide pressure relief to the regulation circuit SC-1.

[0068] Although valve 5 does not exist in the embodiment, it can be advantageous to have such a valve 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 also be used to protect valve 6 during a bake-out mode or a defrost mode in which a high-temperature refrigerant at about 1250 °C flows through the pipe body. Generally, since valve 6 is designed for extremely low temperatures, the polymer seals inside it may not be rated for high temperatures. Therefore, it can be advantageous to protect valve 6 from these high-temperature fluids by closing valve 5.

[0069] In this embodiment, the buffer container 7 has a PRV, which is a safety valve configured to open in response to the pressure in the buffer volume rising above a predetermined safety limit. This pressure relief valve is configured to exhaust through a pipeline such that the released gas is sent outside the cleanroom environment.

[0070] In this embodiment, in addition to the first inlet channel 24, there is a further inlet channel 26 that provides a passage from the inlet conduit 20 to the buffer volume 7. The second inlet channel includes an electrically actuated valve 3 and a check valve 4 that resist the backflow of the regulating fluid from the buffer volume 7 to the inlet conduit 20. The electrically actuated valve 3 is a normally open valve, that is, it opens when there is no power, but generally closes when power is supplied. Therefore, in the case of a total power loss, the power is cut off to open and allow the fluid to flow into the buffer volume, thus providing pressure protection to the system as a result of a power outage. In this embodiment, the valve 3 is connected to a system controller 30 that receives signals from various pressure transducers 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 increase above a predetermined level. In this way, during a pressure spike, by providing pressure relief through the two inlet channels 24 and 26, the fluid flow can be improved and the pressure spike can be quickly alleviated.

[0071] In this embodiment, there is an outlet conduit 28 from the buffer volume 7 to the return conduit 22. The outlet conduit 28 acts to discharge excess pressure from the buffer volume 7 and actually provides a bypass path for the regulating fluid that bypasses the semiconductor regulating circuit SC-1 during a pressure increase to provide pressure relief to the system. In some embodiments, the outlet channel 28 has a check valve 10 that prevents the backflow of the regulating fluid from the return conduit 22 to the buffer volume 7.

[0072] Note that although FIG. 1 shows a single semiconductor wafer regulating circuit and a single pressure regulating device, in some embodiments, there can be a plurality of semiconductor wafer regulating circuits arranged in series. In such a case, the pressure regulating device can play a role in alleviating the pressure increase of all these semiconductor wafer regulating circuits, and / or there can be a plurality of pressure regulating devices having inlets and outlets arranged in series between the cooling system and the regulating circuit to enhance pressure relief, and / or there can be a large-sized buffer container 7 having a plurality of inlet channels.

[0073] FIG. 2 shows another embodiment which, although in a similar embodiment to FIG. 1, provides pressure protection to a plurality of semiconductor conditioning circuits SC-1 and SC-2 arranged in parallel. This embodiment also includes an additional inlet channel 27 to the buffer volume 7, which provides an additional fluid flow path to increase the fluid flow into the buffer volume in response to a pressure spike. The reason for the additional fluid flow may be that there are multiple wafer conditioning circuits and each may receive a pressure spike simultaneously, thus requiring greater pressure relief.

[0074] FIG. 3 shows yet another embodiment where, although downstream of the conditioning circuit but upstream of the connection between the outlet line 22 and the outlet channel 28, one of the inlet channels 26 that provides access to the buffer volume 7 and helps regulate the pressure within the wafer conditioning circuit can be connected to the conditioning fluid outlet line 22. This arrangement also provides effective pressure regulation and can be advantageous when the physical arrangement, layout, and piping of the conditioning circuit allow for further room on this side. In this case, one of the inlet channels is provided on the return line 22 and the outlet channel 28 is downstream of this inlet channel.

[0075] In the following section, different operating modes of the pressure regulating device embodiments are outlined.

[0076] Normal steady operating mode: The conditioning fluid / mixed refrigerant (hereinafter referred to as "fluid") enters the pressure regulating device at 13a on its way towards the conditioning circuit directly connected to the chuck. The fluid flows through the semiconductor chuck SC-1 and exits from this part of the circuit via the connection 13b. The fluid flow path is 13a - 14a - 1 - SC-1 - 11 - 13b.

[0077] The pressure regulating device is designed to regulate pressure in the case of the following two types of failure modes that result in a pressure increase or pressure spike. 1. Pressure spike when the device is operating and has power 2. Pressure spike in the case of a complete power loss

[0078] Fault Mode 1 - When the unit has power: In this scenario, normal operation continues until the fluid pressure is maintained at 90% or less of the operating pressure limit defined by the user. When the fluid pressure begins to approach the operating pressure limit (90% - 93% of the maximum value, also known as the cracking pressure), the pressure regulating valve 6 begins to open partially. As the pressure continues to rise, valve 6 fully opens. At this point, the fluid is diverted to the buffer volume, and an additional flow path of 13a - 14a - 1 - 5 - 6 - 7 - 10 - 11 - 14b - 13b opens for this fluid. The buffer volume is an empty pressure vessel maintained at a low pressure. In comparison, the wafer adjustment circuit within the semiconductor chuck is a series of small conduits through which the fluid flows. As a result, the pressure loss or flow resistance of the fluid is much lower in the buffer volume compared to the adjustment circuit. The outlet of the buffer volume is always connected to the return side of the adjustment circuit, which is always at a lower pressure than the supply side. Overall, this arrangement allows more fluid to flow into the buffer volume than into the adjustment circuit. When the volume that the fluid can occupy increases and the mass flow rate is actively diverted to the buffer volume, the overall pressure within the fluid circuit in and around the adjustment circuit or chuck decreases. If the rate of pressure drop detected by the pressure transducer 2 is not sufficient, valve 3 opens to provide another fluid flow path to the buffer volume. If the event that initially caused the fluid pressure to rise is temporary / transient, the pressure within the fluid system begins to normalize towards the normal operating range. When the pressure drops to 93% of the maximum value, valves 6 and 3 close to isolate the buffer container from the fluid circuit. Since the outlet of the buffer volume is connected to the return side (low - pressure side) of the fluid circuit, the fluid already present within the buffer volume automatically flows back into the fluid circuit again.

[0079] If the event that caused the pressure spike is not transient / temporary and the pressure continues to rise, the supply valve on the fluid adjustment circuit 14a closes to ensure that no new mass of fluid is introduced into this part of the fluid adjustment circuit. The return valve 14b on the circuit remains open to drain as much fluid as possible from the chuck and the buffer volume. After a specified time delay, if the event that caused the pressure rise is still on, the system compressor stops.

[0080] Fault mode 2 - In the case of complete power loss: When the chamber loses all power, it is understood that the flow of fluid in the regulating circuit stops (the compressor turns off). The stagnant fluid expands as it warms up, increasing the fluid pressure. This pressure increase can be sufficient to damage the wafer regulating circuit, or in this embodiment, the chuck SC-1.

[0081] To protect against this fault mode, the following is done. Valves 14a and 14b are closed to isolate the pressure regulating device and the wafer regulating circuit from the rest of the cooling system. Valve 3 (normally open) opens. As a result, a conduit for expansion into the buffer volume is provided to the fluid. If the pressure continues to rise due to insufficient mass flow through valve 3, valve 5 (a pilot-operated valve) opens when the fluid pressure exceeds its rated reverse flow value. Valve 5 is selected to allow reverse flow at a back pressure value lower than the set value of valve 6.

[0082] Subsequently, valve 6 allows additional flow paths into the buffer volume in response to the pressure increase. As a result, the pressure in the fluid circuit decreases. To protect against such a fault mode, the buffer volume should be large enough to accommodate the overall increase in liquid volume as the fluid warms from cryogenic to ambient temperature. This required volume can be accurately estimated based on the fluid properties, the overall internal volume of the fluid regulating circuit, and the internal volume of the chuck. When the power is restored and the chamber operates again, valve 3 closes and valve 5 opens. When the pressure drops to ~90% of the set point of the pressure valve, valve 6 closes. The liquid in the buffer volume is discharged to the return side of the liquid regulating circuit, and normal operation of the unit can be started.

[0083] Check valves (elements 1, 4, 10, 11) serve the purpose of ensuring that fluid does not flow back into the buffer volume or the supply side in case of an abnormal pressure difference.

[0084] Figure 4 schematically shows how the pressure changes within the system when the protection mechanism of the pressure regulating device operates in failure mode 1. In this example, a pressure increase forcing input is applied to the system at 50, and when the pressure rises above a predetermined level of 60, the pressure control valve opens, and pressure removal is provided to the system through access to the buffer volume and a bypass provided through this buffer volume. At 70, pressure removal is maintained by leaving this flow path open, and when the forced pressure is removed at 80, the pressure within the system drops and the pressure control valve closes. At 40, the buffer volume bypass is separated from the system again and normal operation resumes.

[0085] Figure 5 shows how the system functions (failure mode 2) to prevent excessive pressure rise during a power outage. When a power loss occurs, initially the pressure rises rapidly (100). At 110, the pressure control mechanism activates, the buffer volume is connected to the regulating circuit, and the inlet and outlet valves of the system close. As a result of the size of the buffer vessel, the pressure is maintained at a safe level (120).

[0086] Multiple embodiments are possible depending on the configuration of the process chamber and processing steps (parallel wafer processing versus sequential wafer processing). As an example, in a chamber configuration where multiple semiconductor chucks are used in parallel for device manufacturing (each chuck executing the same recipe on a wafer) and each semiconductor chuck is cooled in parallel by the same process chiller, the configuration of FIG. 2 can be adopted. In this embodiment, the principle of pressure regulation remains the same, but it is proposed to use two or more valve sets in parallel to ensure a mass flow rate of fluid sufficient to accommodate the internal volumes of multiple chucks (and a response time commensurate with reducing the pressure).

[0087] In another embodiment of FIG. 3, a set of valves useful for pressure regulation within the fluid regulation circuit can be placed after (downstream of) the semiconductor chuck. This configuration also provides effective pressure regulation and can be implemented based on, among other things, a pressure drop within the chuck, the physical placement / layout and plumbing of the chuck regulation circuit, and one or more of the available clearances.

[0088] Embodiments of this concept can also include multiple things such as using two or more pressure regulating valves 6 in parallel to provide, for example, a faster response time, a greater mass flow rate, etc. These selections are determined by specific requirements.

[0089] The pressure regulating valve 6 can function alone without the need for valve 5. However, if it is necessary to completely isolate the buffer volume during pump maintenance or if valve 6 needs to be replaced, valve 5 functions like a shut-off isolation valve.

[0090] In some embodiments, the pressure control valve or pressure regulating valve 6 is a "cryogenic economizer". These valves are generally used to maintain a static head pressure in large cryogenic tanks (such as liquid N2, O2, etc.). The control of pressure in a dynamic operating environment is a novel use for this type of valve.

[0091] Valves 3 and 5 are actively controlled using a simple electronic controller. This electronic controller can be the main controller of the cryochiller or a secondary dedicated controller 30. The controller reads the pressure value from the pressure transducer 2 within the assembly and relays a signal for OPEN or CLOSE to the valve.

[0092] The entire assembly can have a pressure relief valve PRV set to an appropriate exhaust pressure as shown on the buffer vessel. From the pressure relief valve, there can be an exhaust pipeline that ensures exhaust to the outside of the clean room.

[0093] In some embodiments, when the pressure regulating device operates frequently within a short period of time, especially in a mode where the set point temperature of the refrigerant mixture is low, a situation may occur where liquid refrigerant accumulates in the buffer vessel. Some accumulation is expected and not a problem, but if excessive refrigerant accumulates, it is preferable to have means to evaporate the liquid and return the refrigerant to the cooling system for stable operation. Heating can be by electric heating, and by opening valve 5, high-temperature refrigerant can be introduced into the buffer volume 7 through pipeline 27 (see, for example, FIG. 2). This high-temperature refrigerant mixes with the cold liquid in the buffer volume and evaporates the cold liquid. After a specified time delay, or by sensing the temperature of the buffer vessel or the pressure inside the buffer vessel, etc., valve 5 can be closed, or the heater can be turned off.

[0094] In some embodiments, this heating mechanism operates in response to detecting frequent operation of the system or by a combination of controller logic and (single or multiple) temperature sensors. The temperature sensor (thermocouple) can be attached, for example, to the outer wall of the buffer vessel. If there are more than a specified number of pressure relaxation events within a given (specifiable) time and the surface temperature of the tank remains below a specified value after these pressure relaxation events, a high-temperature gas / electric heating event can be triggered.

[0095] Alternatively, an electric heater can be provided on / inside the tank, and this electric heater can be operated for a specified time after all pressure relaxation events or when the surface temperature of the tank remains below a specific value for a predetermined time regardless of whether a pressure relaxation event has occurred.

[0096] In summary, at least some embodiments provide the following functionality. 1. The ability to control the pressure within the thermal regulation circuit of a semiconductor wafer over a wide temperature range (from cryogenic temperatures to above ambient temperature). In this regard, when heating rather than cooling is required, heated refrigerant can be supplied from the cooling system to the regulation circuit by passing the refrigerant through a heat exchanger or by diverting heated refrigerant from the warm part of the cooling system. 2. Pressure control capabilities for direct refrigerant cooling type systems and secondary fluid cooling type systems. 3. The ability to reduce the need for emergency shut-off, subsequent maintenance, and startup procedures when pressure spikes are present by dynamically controlling the pressure (not only by venting using a relief valve). 4. Having user - settable pressure limit setpoints and the ability to use the same device over a wide pressure control band (without the need to physically exchange valves to change the pressure setpoint). 5. The ability to provide high resolution for pressure control setpoints by using multiple numbers and types of valves. 6. The ability to ensure that the process parameters generally prioritized in semiconductor processing are reproducible (by dynamic control and fine setpoint resolution capabilities).

[0097] By using a combination of mechanically actuated valves and electrically assisted (electric or pneumatic) valves, solutions for most failure modes are provided.

[0098] Adding the pressure regulation device of the embodiment to existing equipment can enhance the operating envelope of this equipment with respect to temperature, pressure, and safety aspects.

[0099] In this specification, exemplary embodiments of the present invention have been disclosed in detail with reference to the accompanying drawings. However, the present invention is not limited to the exact embodiments, and it is understood that those skilled in the art can make various changes and modifications in the embodiments without departing from the scope of the present invention defined by the appended utility model registration claims and their equivalents.

Explanation of Reference Numerals

[0100] 1, 4, 10, 11 Check valves 2 Pressure transducer 3 Flow control valve, usually open (ON / OFF), can be pneumatically or electromagnetically actuated 4 Check valve 5 Pilot-operated normally closed flow control valve (ON / OFF), can be pneumatically or electromagnetically actuated 6 (Mechanically actuated) Pressure regulating valve 7 Buffer volume in the form of a pressure vessel 10 Check valve 11 Check valve 12 Pressure transducer 13a, 13b Connections to the cooling system 14a, 14b System inlet and outlet valves 20 Inlet pipeline 22 Return pipeline 24, 26, 27 Inlet channels 28 Outlet channel 30 System controller 40 Normal operating pressure 50 Forced pressure increase 60 Start of the pressure control mechanism 70 Pressure maintenance 80 Removal of the pressure forcing effect 100 Pressure increase during power loss 110 Start of the pressure control mechanism 120 Pressure maintained over a certain period

Claims

A pressure regulating device for relieving the pressure rise in a semiconductor wafer regulating circuit through which a regulating fluid flows, comprising: a buffer vessel including an inlet channel and an outlet channel; the inlet channel is configured to be in fluid communication with the high-pressure position of the semiconductor wafer regulating circuit during operation, and the outlet channel is configured to be in fluid communication with the low-pressure position during operation; the inlet channel includes at least one pressure control valve configured to close the inlet channel so that the buffer vessel is isolated from the high-pressure position of the semiconductor wafer regulating circuit during normal operation, and to open the inlet channel in response to the pressure in the semiconductor wafer regulating circuit exceeding a predetermined pressure level; A pressure regulating device characterized by the above.

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

3. The pressure control valve includes a mechanically spring-biased valve. The pressure regulating device according to claim 1 or 2. The pressure regulating device according to claim 1 or 2.

4. The pressure regulating device further includes at least one pressure sensor for sensing the pressure of the regulating fluid, and a control circuit configured to generate a control signal in response to a signal received from the at least one pressure sensor. The pressure regulating device according to any one of claims 1 to 3. The pressure regulating device according to any one of claims 1 to 3.

5. The control circuit is configured to generate a control signal for opening the pressure control valve in response to the at least one pressure sensor indicating that a predetermined pressure level has been reached. The pressure regulating device according to claim 4. The pressure regulating device according to claim 4.

6. The pressure regulating device is configured to be able to select a predetermined pressure level at which the pressure control valve opens. The pressure regulating device according to claim 3 or 5. The pressure regulating device according to claim 3 or 5.

7. The inlet channel further includes a second valve, which is configured to close to isolate the pressure control valve and the buffer vessel from the semiconductor wafer regulating circuit when no power is supplied and to open when power is supplied. The pressure regulating device according to any one of claims 1 to 6. The pressure regulating device according to any one of claims 1 to 6.

8. The buffer vessel includes at least one additional inlet channel that is in fluid communication with a position at a higher pressure than the position with which the outlet channel is in fluid communication. The at least one additional inlet channel includes an electrically actuated valve that closes when no power is supplied and opens when power is supplied. The pressure regulating device according to any one of claims 1 to 7.

9. The control circuit is configured to generate a control signal for opening the electro-mechanical valve in the at least one additional inlet channel in response to the at least one pressure sensor indicating that a predetermined pressure level has been reached. The pressure regulating device according to claim 8 when dependent on claim 4.

10. The at least one additional inlet channel further includes a check valve that inhibits flow from the semiconductor wafer regulating circuit to the buffer vessel via the at least one additional inlet channel. The pressure regulating device according to claim 8 or 9.

11. The pressure regulating device includes an inlet pipeline that receives a regulating fluid from a cooling system and supplies the regulating fluid to the semiconductor wafer regulating circuit, and a return pipeline that receives the regulating fluid from the semiconductor wafer regulating circuit and returns the regulating fluid to the cooling system. The inlet channel is connected to the inlet pipeline. The pressure regulating device according to any one of claims 1 to 10.

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

13. The pressure regulating device includes a system inlet valve and a system outlet valve for separating the pressure regulating device and the semiconductor wafer regulating circuit from the cooling system. The system inlet valve is provided on the inlet pipeline, and the system outlet valve is provided on the return pipeline. The system inlet valve and the system outlet valve open when power is supplied and close when power is not supplied. The pressure regulating device according to claim 11 or 12.

14. The control circuit is configured to close the system inlet valve in response to the sensed pressure rising above a further predetermined pressure level that is higher than the predetermined pressure level. The pressure regulating device according to claim 13 when dependent on claim 4.

15. The control circuit is configured to close the system outlet valve in response to the sensed pressure rising to the further predetermined pressure level. The pressure regulating device according to claim 14.

16. The control circuit is configured to close the system outlet valve after a predetermined time. The pressure regulating device according to claim 14.

17. The control circuit is configured to open the system inlet valve in response to the sensed pressure drop. The pressure regulating device according to any one of claims 14 to 16. **Claim 18** The inlet channel transports a regulating fluid containing a two-phase mixture of fluids. The pressure regulating device according to any one of claims 1 to 17. **Claim 19** The size of the buffer vessel is sufficient to accommodate the expansion of the regulating fluid within the pressure regulating device as it warms from a low operating temperature to room temperature. The pressure regulating device according to any one of claims 1 to 18. **Claim 20** The semiconductor wafer regulating circuit includes a plurality of semiconductor wafer regulating circuits arranged in parallel for cooling a plurality of semiconductor wafers. The pressure regulating device according to any one of claims 1 to 19. **Claim 21** The at least one pressure sensor includes a plurality of pressure sensors configured to sense the pressure of the regulating fluid within the plurality of semiconductor wafer regulating circuits. The pressure regulating device according to claim 20 when dependent on claim 4. **Claim 22** The pressure regulating device includes a heating mechanism for warming the buffer vessel, and the control circuit is configured to control the heating mechanism to warm the buffer vessel in response to at least one of the actuation of the pressure control valve occurring more frequently than a predetermined frequency, and the temperature of the buffer vessel dropping below a predetermined level and remaining below the predetermined temperature for a predetermined time. The pressure regulating device according to claim 4. **Claim 23** A semiconductor wafer cooling device comprising a cooling system and a pressure regulating device according to any one of claims 1 to 22. characterized by that. **Claim 24** The pressure regulating device receives refrigerant from the cooling system. The semiconductor wafer cooling device according to claim 23. **Claim 25** A method of pressure protecting a semiconductor wafer regulating circuit, the method comprising connecting an inlet channel and an outlet channel of a pressure regulating device according to any one of claims 1 to 22 to the semiconductor wafer regulating circuit in fluid communication with an inlet channel and an outlet channel of the semiconductor wafer regulating circuit, the inlet channel of the semiconductor wafer regulating circuit being configured to receive a regulating fluid from a cooling system, and the outlet channel of the semiconductor wafer regulating circuit being configured to return the regulating fluid to the cooling system. characterized by that method.

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