Wafer stage cooling system

Abstract

To provide a wafer stage cooling system capable of efficiently cooling a wafer stage with a simple configuration.SOLUTION: A wafer stage cooling system for cooling a wafer stage for supporting a semiconductor wafer to be an object of plasma etching comprises: a first cooling device configured so that a first coolant circulates; a heat exchanger configured so that heat exchange is performed between the first coolant and a second coolant, which circulates between the heat exchanger and the wafer stage; and a heat pipeline in which the second coolant is encapsulated. The heat pipeline includes: a condensation unit for the second coolant condensing from a vapor-phase state to a liquid-phase state by heat exchange with the first coolant; an evaporation unit for the second coolant in the liquid-phase state evaporating via cooling of the wafer stage; and at least one circulation line for making the second coolant circulate between the condensation unit and the evaporation unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a wafer stage cooling system for cooling a wafer stage. [Background technology]

[0002] The manufacturing process of a semiconductor plant includes an etching process for forming deep trenches on semiconductor wafers. The temperature of the semiconductor wafers during the etching process must be maintained at an extremely low temperature. One example of a specific means for achieving this is disclosed in Patent Document 1. This document discloses a refrigerant pipe through which a fluorocarbon refrigerant circulates to cool a wafer stage that supports the semiconductor wafer, and a refrigeration cycle incorporating a cooler that cools the fluorocarbon refrigerant. The extremely low temperature fluorocarbon refrigerant cooled by the refrigeration cycle is supplied to the wafer stage, and the temperature of the wafer stage is maintained at an extremely low temperature (see Figure 3(b) of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-079539 Summary of the Invention [Problem to be solved by the invention]

[0004] With the miniaturization, high stacking, and three-dimensionalization of semiconductors, there is a demand for even finer deep trenches, and there is also a demand for the temperature of semiconductor wafers to be kept even lower during etching. To achieve this, it is desirable to efficiently cool the wafer stage with a simple configuration.

[0005] An object of the present disclosure is to provide a wafer stage cooling system that can efficiently cool a wafer stage with a simple configuration. [Means for solving the problem]

[0006] A wafer stage cooling system according to at least one embodiment of the present disclosure includes: 1. A wafer stage cooling system for cooling a wafer stage that supports a semiconductor wafer to be plasma etched, comprising: a first cooling device configured to circulate a first refrigerant; a heat exchanger configured to perform heat exchange between the first refrigerant and a second refrigerant; a heat pipeline containing the second refrigerant and circulating between the heat exchanger and the wafer stage; Equipped with The heat pipeline is a condensation section for condensing the second refrigerant from a gas phase state to a liquid phase state by heat exchange with the first refrigerant; an evaporation section through which the second refrigerant in the liquid phase evaporates by cooling the wafer stage; at least one circulation line for circulating the second refrigerant between the condenser and the evaporator; Includes. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a wafer stage cooling system that can efficiently cool a wafer stage with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a wafer stage cooling system according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of a first cooling device according to one embodiment. [Figure 3] FIG. 2 is a schematic diagram of a condenser according to an embodiment. [Figure 4] FIG. 2 is a schematic cross-sectional view of a wafer stage according to an embodiment. [Figure 5] FIG. 10 is a schematic diagram of a heat pipeline according to a modified example. [Figure 6] FIG. 10 is a schematic diagram of a wafer stage according to a modified example. [Figure 7] FIG. 1 is a schematic diagram of a first cooling device with additional components. [Figure 8] FIG. 10 is a schematic view of a first cooling device according to a modified example. [Figure 9] FIG. 9 is a partially enlarged view of FIG. 8. [Figure 10] FIG. 10 is a schematic diagram of a wafer stage cooling system according to another embodiment. [Figure 11] FIG. 10 is a schematic diagram of a wafer stage cooling system according to a modified example. [Figure 12] This is a basic conceptual diagram of a thermal cycle incorporated into a semiconductor factory. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," or "have" one element are not exclusive expressions that exclude the presence of other elements. Note that the same components will be denoted by the same reference numerals and the description thereof will be omitted.

[0010] <Overview of Wafer Stage Cooling System 2> 1 is a schematic diagram of a wafer stage cooling system 2 installed in a semiconductor factory 1 according to an embodiment of the present disclosure. The wafer stage cooling system 2 includes a plasma processing apparatus 6 that processes semiconductor wafers 3 for plasma etching.

[0011] The plasma processing apparatus 6 is equipped with a sealable chamber 7, inside which are arranged a wafer stage 4 that supports the semiconductor wafer 3, a gas shower head 8 that supplies processing gas into the chamber 7, and an electrode unit (not shown) for generating plasma. After the processing gas from the gas shower head 8 fills the internal space of the chamber 7, which has been placed in a vacuum state, high-frequency power is applied to the electrode unit. This generates plasma above the semiconductor wafer 3, and the semiconductor wafer 3 is subjected to plasma etching. As a result, fine deep grooves are formed in the semiconductor wafer 3.

[0012] To achieve even higher accuracy plasma etching than conventional techniques, it is necessary to reduce the temperature of the semiconductor wafer 3 during processing to a lower temperature than conventional techniques. This is preferably achieved by a highly efficient refrigeration cycle with a simple configuration. In the present disclosure, a first refrigerant R1 and a second refrigerant R2 are used as a means for achieving this. More specifically, the semiconductor wafer 3 is cooled by cooling the wafer stage 4 using the second refrigerant R2, and the second refrigerant R2, whose temperature has risen after cooling the wafer stage 4, is then cooled using the first refrigerant R1.

[0013] In more detail, the wafer stage cooling system 2 comprises a first cooling device 10 including a first refrigerant circulation line 11 configured to circulate a first refrigerant R1, a heat exchanger 9 configured to perform heat exchange between the first refrigerant R1 and a second refrigerant R2, and a heat pipeline 30 containing the second refrigerant R2 that circulates between the heat exchanger 9 and the wafer stage 4.

[0014] Any refrigerant may be used as the first refrigerant R1 and the second refrigerant R2. By way of example only, the first refrigerant R1 and the second refrigerant R2 may be a single refrigerant with a low environmental impact, such as nitrogen, neon, or argon, or a mixed refrigerant containing multiple single refrigerants. When a mixed refrigerant is used, the blend ratio of the single refrigerants can be adjusted, allowing the wafer stage cooling system 2 to exhibit cooling performance suited to the cooling load in the plasma processing apparatus 6. The first refrigerant R1 and the second refrigerant R2 may be air, for example. Furthermore, the present disclosure does not exclude the use of refrigerants traditionally used in refrigeration systems in semiconductor factories 1, such as PFAS (organofluorine-containing synthetic compounds), Novec (registered trademark), or Fluorinert (registered trademark).

[0015] FIG. 2 is a schematic diagram of a first cooling device 10 according to an embodiment of the present disclosure. The first cooling device 10 is a refrigerator that employs a reverse Brainton cycle. The first cooling device 10 includes a compressor 12, an expansion turbine 13, and a heat exchanger 14, which are arranged in series in this order from the upstream side of a first refrigerant circulation line 11. The compressor 12 includes compressors 12a, 12b, and 12c, which are arranged in series in this order from the upstream side. The compressors 12a and 12b are integrated via a motor 15a, and the compressor 12c and the expansion turbine 13 are integrated via a motor 15b. The heat exchanger 14 is a pipe arranged inside the heat exchanger 9. Note that the motor 15b is not an essential component of the present disclosure. When the cooling temperature of the semiconductor wafers 3 is relatively high, the motor 15b is not necessary.

[0016] Furthermore, in the first refrigerant circulation line 11 of this example, first heat exchangers 17 are respectively disposed between the compressors 12a and 12b, between the compressors 12b and 12c, and between the compressor 12b and the expansion turbine 13. The first heat exchangers 17 are configured to cool the first refrigerant R1 by exchanging heat between the first refrigerant R1 and a heat medium (not shown), which may be, for example, water. The first refrigerant circulation line 11 of this example also includes a second heat exchanger 18 for heat exchange between the cryogenic first refrigerant R1 flowing from the compressor 12c to the expansion turbine 13 and the temperature-increased first refrigerant R1 flowing from the heat exchange unit 14 to the compressor 12a. In the first refrigerant circulation line 11 of this example, the first refrigerant R1 circulates while maintaining its gas phase. Therefore, the cryogenic first refrigerant R1 flowing from the expansion turbine 13 to the heat exchange unit 14 is in a gas phase.

[0017] 2 is merely an example. As will be described later, other components may be additionally applied to the first cooling device 10 (see FIG. 7). Also, a refrigeration cycle other than the reverse Brainton cycle may be applied to the first cooling device 10 (details will be described later with reference to FIGS. 8 and 9).

[0018] Returning to FIG. 1 , the heat pipeline 30 includes a condenser 31 disposed in the heat exchanger 9, an evaporator 32 disposed in the wafer stage 4, and at least one circulation line 35. The condenser 31 is configured to condense the second refrigerant R2 from a gas phase to a liquid phase through heat exchange with the first refrigerant R1. The evaporator 32 is configured to evaporate the second refrigerant R2 in a liquid phase by cooling the wafer stage 4. The circulation line 35 is a pipe member configured to circulate the second refrigerant R2 between the condenser 31 and the evaporator 32.

[0019] The heat pipeline 30 is not provided with a power source, such as a pump, fan, or blower, that consumes electricity to provide refrigerant circulation power. If the refrigerant circulation occurs without a power source, it is not important to the present disclosure whether the heat pipeline 30 is a pipe integrated with the condenser 31 or evaporator 32, or a pipe separate from the condenser 31 or evaporator 32. FIG. 1 merely shows a conceptual diagram of the heat pipeline 30, and the specific configurations of the condenser 31 (see FIG. 3), evaporator 32 (see FIG. 4), and circulation line 35 (see FIGS. 1 and 3), which will be described later, are merely examples.

[0020] In the wafer stage cooling system 2 shown in FIG. 1, the second refrigerant R2 cooled by the first cooling device 10 is supplied to the wafer stage 4, thereby cooling the wafer stage 4. The heat pipeline 30 circulates the second refrigerant R2 without a power source such as a pump, simplifying the configuration of the wafer stage cooling system 2. Furthermore, in the heat pipeline 30, the second refrigerant R2 transports heat at high speed by repeatedly evaporating and condensing, enabling efficient cooling of the wafer stage 4. Furthermore, in the evaporation section 32, the second refrigerant R2 changes from a liquid phase to a gas phase, so the temperature of the second refrigerant R2 flowing out of the evaporation section 32 remains roughly constant. This stabilizes the amount of heat exchange between the wafer stage 4 and the second refrigerant R2, allowing the wafer stage 4 to be maintained within a desired temperature range.

[0021] In some embodiments, the condenser 31 is located vertically above the evaporator 32, and the heat pipeline 30 is a thermosiphon heat pipe in which the second refrigerant R2 in a liquid phase moves from the condenser 31 to the evaporator 32 by its own weight. This configuration further simplifies the configuration of the heat pipeline 30 compared to a type in which a wick is provided inside the circulation line 35. However, the heat pipeline 30 of the present disclosure is not limited to the thermosiphon type, and an embodiment in which a wick is provided inside the circulation line 35 may also be adopted. The second refrigerant R2 in a liquid phase condensed in the condenser 31 moves to the evaporator 32 by capillary action in the wick. In this case, it is not essential that the condenser 31 be located above the evaporator 32.

[0022] 2 is employed for the first cooling device 10, so that the first refrigerant R1 at an extremely low temperature expanded in the expansion turbine 13 is introduced into the heat exchanger 14. This allows the temperature of the second refrigerant R2 in a liquid phase to be sufficiently reduced in the heat exchanger 14, making it possible to sufficiently cool the semiconductor wafer 3 on the wafer stage 4.

[0023] In the configuration in which the first refrigerant R1 circulates in the first refrigerant circulation line 11 of the first cooling device 10 while maintaining the gas phase, a liquid refrigerant such as an organic fluorine compound or a fluorine-based inert liquid is not used as the first refrigerant R1, which reduces the environmental load and allows the temperature of the heat exchange section 14 to be kept extremely low.

[0024] <Heat Pipeline 30 (First Example)> A heat pipeline 30 according to a first example will be described with reference to FIGS. 1, 3 and 4. FIG.

[0025] First, the circulation line 35 of the heat pipeline 30 will be described with reference to Fig. 1. The circulation line 35 includes a single piping line 36 that connects the condenser section 31 and the evaporator section 32. In the example of Fig. 1, multiple piping lines 36 are arranged, but the present disclosure is not limited to this, and the number of piping lines 36 may be one.

[0026] The single piping line 36 may have a structure in which a plurality of pipes are connected together, or may be formed by a single pipe. Furthermore, the piping line 36 may be a pipe member integrated with the condenser 31, or may be a pipe member separate from the condenser 31 (these two examples will be described in detail later).

[0027] The single piping line 36 defines a liquid-phase flow path for the second refrigerant R2 from the condenser 31 to the evaporator 32, and also defines a vapor-phase flow path for the second refrigerant R2 from the evaporator 32 to the condenser 31. That is, the space formed inside the single piping line 36 includes a liquid-phase flow path for the second refrigerant R2 and a vapor-phase flow path for the second refrigerant R2. According to the above configuration, the configuration of the heat pipeline 30 can be further simplified compared to an embodiment in which the liquid-phase flow path and the vapor-phase flow path are formed in two separate piping lines (see FIG. 5).

[0028] Next, the condenser 31 will be described with reference to Fig. 3. This figure is a schematic diagram of the condenser 31 according to the first example. The condenser 31 is integrated with each of the multiple piping lines 36. More specifically, the condenser 31 and the piping lines 36 form a cylindrical pipe member with a bottom, and the condenser 31 forms one end of the pipe member.

[0029] The condenser section 31 is inserted into the heat exchanger 9 and is connected to a heat sink 29 arranged inside the heat exchanger 9. The heat sink 29 promotes heat exchange between the second refrigerant R2 in a gas phase flowing into the condenser section 31 and the first refrigerant R1 flowing into the heat exchange section 14 of the first cooling device 10. This allows the second refrigerant R2 to quickly condense from a gas phase to a liquid phase in the condenser section 31. The second refrigerant R2 in a liquid phase moves due to its own weight and flows through the piping line 36. As a result, a liquid pool of the second refrigerant R2 is formed inside the piping line 36 located below the heat exchanger 9.

[0030] 3, in which the condenser 31 closes the piping line 36. Although detailed illustration is omitted, the piping line 36 may be a pipe member with an open upper end. In this case, the second refrigerant R2 in a gaseous state flowing through each of the multiple piping lines 36 flows into the heat exchange container constituting the heat exchanger 9, and changes from the gaseous state to a liquid state through heat exchange with the first refrigerant R1. In other words, the heat exchange container of the heat exchanger 9 functions as the condenser 31, and the condenser 31 has a configuration separate from the piping line 36. In this case, the heat sink 29 is not provided.

[0031] Returning to FIG. 1, the evaporation section 32 according to the first example will be described. The evaporation section 32 is an internal flow path 5 formed inside the wafer stage 4. The internal flow path 5 is arranged so as to overlap the semiconductor wafer 3 in a plan view, and various shapes can be adopted for the internal flow path 5. In FIG. 1, the internal flow path 5 is formed in the mounting portion 41 of the wafer stage 4 that comes into direct contact with the semiconductor wafer 3, but the present disclosure is not limited to this, and details will be described later (see FIG. 6).

[0032] FIG. 4 shows an example of a specific shape of the internal flow path 5. The internal flow path 5 is formed in a spiral shape in a plan view. A plurality of piping lines 36 are connected to the internal flow path 5 at different positions in a plan view. Each piping line 36 is inserted into the wafer stage 4 from below and communicates with the internal flow path 5. The second refrigerant R2 in a liquid phase that flows from the piping line 36 into the internal flow path 5 exchanges heat with the wafer stage 4 as it flows through the internal flow path 5. As a result, the semiconductor wafer 3 being processed is cooled. The second refrigerant R2 in a liquid phase evaporates in the internal flow path 5 and returns to the condenser 31 via the piping line 36.

[0033] In a configuration in which the evaporation section 32 is the internal flow path 5 formed in the wafer stage 4, the second refrigerant R2 changes from a liquid state to a gas state as it flows through the internal flow path 5 of the wafer stage 4. This allows for more uniform cooling of the wafer stage 4. Furthermore, in an embodiment in which multiple piping lines 36 are connected to the spiral-shaped internal flow path 5 at different positions, the second refrigerant R2 in a liquid state is supplied to the internal flow path 5 at multiple positions. This allows for more uniform evaporation of the second refrigerant R2 in the internal flow path 5, allowing for more uniform cooling of the wafer stage 4.

[0034] The present disclosure is not limited to the internal flow path 5 being spiral in plan view. The internal flow path 5 may be a plurality of annular flow paths arranged concentrically. In this case, a plurality of piping lines 36 are connected to each of the plurality of annular flow paths.

[0035] <Heat pipeline 30A (second example)> A heat pipeline 30A according to a second example will be described with reference to Figure 5. The circulation line 35A of the heat pipeline 30A includes a first piping line 351 that defines a liquid-phase flow path for the second refrigerant R2 from the condenser 31 to the evaporator 32, and a second piping line 352 that defines a gas-phase flow path for the second refrigerant R2 from the evaporator 32 to the condenser 31. The first piping line 351 and the second piping line 352 are different pipe members, and therefore the liquid-phase flow path and the gas-phase flow path are formed by separate pipe members.

[0036] The first piping line 351 extends from the heat exchanger 9 to the internal flow path 5 of the wafer stage 4, and the second piping line 352 extends from the internal flow path 5 to the heat exchanger 9. In a second example, the heat exchange vessel that constitutes the heat exchanger 9 functions as the condenser 31, and a liquid pool of the second refrigerant R2 may be formed inside the heat exchange vessel. In the example of Fig. 5, there is one circulation line 35A made up of the first piping line 351 and the second piping line 352, but multiple circulation lines 35A may be provided.

[0037] <Wafer stage 4A (second example)> 6 is a schematic diagram of a wafer stage 4A according to a second example. The wafer stage 4A includes a mounting portion 41 on which a semiconductor wafer 3 is placed, and a heat sink portion 42 that supports the mounting portion 41 from below. The heat sink portion 42 is formed from a material such as copper or aluminum, which has higher heat dissipation properties than the material that forms the mounting portion 41. In the example of FIG. 6, an internal flow path 5 is formed inside the heat sink portion 42.

[0038] In the mounting part 41, which has the function of accommodating an electrode part for etching processing in addition to the function of supporting the semiconductor wafer 3, there are significant design constraints for arranging the internal flow path 5. In this regard, according to the above-described configuration, the internal flow path 5 is formed in the heat sink part 42 that supports the mounting part 41, so that the internal flow path 5 can be arranged according to the amount of heat required for cooling the semiconductor wafer 3.

[0039] <Other variations> 7, additional components that may be included in the wafer stage cooling system 2 will be described. The wafer stage cooling system 2 may further include a storage tank 47 that stores liquefied gas to be used as a process gas in the semiconductor factory 1, and a liquefied gas line 45 through which the liquefied gas discharged from the storage tank 47 flows. The liquefied gas may be liquid hydrogen, liquid oxygen, liquid argon, or the like. The liquefied gas flowing through the liquefied gas line 45 may be used for cooling in a cryopump, and then used as a process gas in an air conditioner or the like in the semiconductor factory 1.

[0040] 7, the heat exchanger 9 may be configured to cool the second refrigerant R2 not only by heat exchange between the first refrigerant R1 and the second refrigerant R2, but also by heat exchange between the second refrigerant R2 and a third refrigerant R3 as a liquefied gas. According to the above configuration, the second refrigerant R2 can be cooled using cold energy recovered from the liquefied gas used in the semiconductor factory 1, thereby reducing the cooling load of the first cooling device 10.

[0041] Furthermore, a cooling heat exchanger 48 may be further disposed on the liquefied gas line 45. The cooling heat exchanger 48 is configured to cool the first refrigerant R1 by heat exchange between the first refrigerant R1 flowing from the expansion turbine 13 toward the heat exchange unit 14 and the third refrigerant R3, which is a liquefied gas flowing through the liquefied gas line 45. With the above configuration, the second refrigerant R2 flowing from the expansion turbine 13 toward the heat exchange unit 14 is cooled by the liquefied gas, thereby further reducing the cooling load of the first cooling device 10.

[0042] A first cooling device 10A according to a modified example will be described with reference to Figures 8 and 9. In the first cooling device 10A, the first refrigerant R1 circulating through the first refrigerant circulation line 11 changes between a liquid phase and a gas phase as it circulates between the compressor 121 and the evaporator 122. The evaporator 122 is disposed inside the heat exchanger 9 and is capable of exchanging heat with the second refrigerant R2 flowing through the heat pipeline 30. Furthermore, in order to bring the temperature of the first refrigerant R1 flowing into the evaporator 122 to an extremely low temperature liquid phase, the cold energy of the liquefied gas flowing through the above-mentioned liquefied gas line 45 is utilized by the cold energy utilization line 150.

[0043] The first refrigerant circulation line 11 of the first cooling device 10A includes a refrigerant supply line 111 from a compressor 121 to an evaporator 122, and a refrigerant return line 112 from the evaporator 122 to the compressor 121. A condenser 123 and multiple heat exchangers 129 are arranged in series along the refrigerant supply line 111, starting from the upstream side. The first refrigerant R1 in a liquid phase flowing out of the condenser 123 passes through the multiple heat exchangers 129 in sequence. A phase separator 128 is further arranged between the two heat exchangers 129 arranged in series. A portion of the first refrigerant R1 passing through the phase separator 128 flows to the downstream heat exchanger 129, while the remaining first refrigerant R1 flows to the refrigerant return line 112. The first refrigerant R1 flowing out of the most downstream heat exchanger 129 evaporates in an evaporator 122 located inside the heat exchanger 129, and the second refrigerant R2 flowing through the heat pipeline 30 is cooled.

[0044] FIG. 9 is a detailed schematic diagram of the configuration surrounded by dashed line M in FIG. 8 and the cold energy utilization line 150. A fourth refrigerant R4, which is cooled by heat exchange with the liquefied gas flowing through the liquefied gas line 45, circulates through the cold energy utilization line 150. In FIG. 9, the fourth refrigerant R4 is cooled by heat exchange with the liquefied gas in the heat exchanger 131. The fourth refrigerant R4 discharged from the heat exchanger 131 exchanges heat with the first refrigerant R1 in a liquid phase flowing through the refrigerant supply line 111 in a plurality of heat exchangers 132, and the first refrigerant R1 is cooled to an extremely low temperature. The fourth refrigerant R4 that has passed through all the heat exchangers 132 is returned to the heat exchanger 131 by the power source 133.

[0045] <Other embodiments> A wafer stage cooling system 201 according to another embodiment will be described with reference to Figure 10. Wafer stage cooling system 201 includes a first cooling device 210 through which a first refrigerant R1 circulates, and a second cooling device 220 through which a second refrigerant R2 circulates.

[0046] The first cooling device 210 is a refrigeration system to which a Claude cycle is applied. A first compressor 211 that compresses a first refrigerant R1 and a first expansion valve 231 that expands the first refrigerant R1 are arranged on a first refrigerant circulation line 203 of the first cooling device 210. The first refrigerant R1 changes from a gas phase (or a gas-liquid two-phase state) to a liquid phase while passing through the first expansion valve 231. The first refrigerant circulation line 203 includes a supply line 218 from the first compressor 211 to the first expansion valve 231 and a return line 219 from the first expansion valve 231 to the first compressor 211.

[0047] The first cooling device 210 includes a plurality of first heat exchangers 241 that perform heat exchange between a high-temperature first refrigerant R1 flowing through a supply line 218 and a low-temperature first refrigerant R1 arranged in a return line 219. A portion of the first refrigerant R1 flowing through the supply line 218 is liquefied by an expansion turbine 230 and then supplied to the return line 219.

[0048] The second cooling device 220 includes a second expansion valve 222 for expanding the second refrigerant R2, a liquid supply line 225 for supplying the second refrigerant R2 in a liquid phase state discharged from the second expansion valve 222 to the internal flow path 5 of the wafer stage 4, and a gas return line 226 for returning the second refrigerant R2 in a gas phase state discharged from the internal flow path 5 to the second expansion valve 222. The gas return line 226 is further provided with a heater 227 that adjusts the temperature of the second refrigerant R2, and a blower 228 that sends out the second refrigerant R2 in a gas phase state that has passed through the heater 227.

[0049] The gas return line 226 is configured to pass the second refrigerant R2 delivered by the blower 228 through each of the multiple first heat exchangers 241. In each first heat exchanger 241, the second refrigerant R2 is cooled by the first refrigerant R1 in a liquid phase flowing through the return line 219. This reduces the temperature of the second refrigerant R2 at the inlet of the second expansion valve 222, making it possible to make the temperature of the second refrigerant R2 discharged from the second expansion valve 222 extremely low. Furthermore, a heat exchanger 243 separate from the first heat exchanger 241 may be provided. The heat exchanger 243 exchanges heat only between the first refrigerant R1 flowing through the return line 219 and the second refrigerant R2 flowing through the gas return line 226.

[0050] A wafer stage cooling system 201A according to a modified example will be described with reference to Figure 11. The second cooling device 220A of the wafer stage cooling system 201A includes a gas return line 226A, and the gas return line 226A includes a first gas return line 261 for guiding the second refrigerant R2 from the internal flow path 5 to the blower 228, and a second gas return line 262 for guiding the second refrigerant R2 from the blower 228 to the second expansion valve 222. The second gas return line 262 is configured to pass the second refrigerant R2 through each of the multiple first heat exchangers 241.

[0051] 11 further includes a second heat exchanger 242. The second heat exchanger 242 is configured to cool the second refrigerant R2 by exchanging heat between the second refrigerant R2 flowing through the first gas return line 261 and the first refrigerant R1 flowing through the return line 219 of the first cooling device 10. Because the second refrigerant R2 is cooled not only in the second gas return line 262 but also in the first gas return line 261, it is possible to extremely reduce the temperature of the second refrigerant R2.

[0052] <Other> In semiconductor factory 1, various liquefied gases such as liquid nitrogen, liquid argon, and liquid hydrogen are used in large quantities as process gases. On the other hand, in semiconductor factory 1, large amounts of cold energy are required for etching equipment, cryopumps, lithography equipment, cold water production equipment, air conditioners, dehumidifiers, and the like, which account for a certain percentage of the electricity consumed in semiconductor factory 1. The inventors of the present application believed that if a thermal cycle were constructed in which the cold energy contained in the above-mentioned liquefied gases was used in these devices, it would be possible to reduce power consumption in semiconductor factory 1 and contribute to reducing the environmental impact.

[0053] Figure 12 shows the basic concept for constructing the above-mentioned thermal cycle. According to this figure, after the above-mentioned cold energy is used in the etching process and the like in the semiconductor factory 1, it is also used in the separation and purification process such as separation membrane / PSA. Furthermore, if liquid hydrogen is generated on-site in the semiconductor factory 1, the liquid hydrogen can be used not only in the etching process and the like but also in the lithography process, and then further used in the separation and purification process. The hydrogen gas used in the separation and purification process can be supplied to a power generator installed in the semiconductor factory 1, or can be reused in the lithography process.

[0054] <Summary> The contents of the above-described embodiments can be understood, for example, as follows.

[0055] 1) A wafer stage cooling system (2) according to at least one embodiment of the present disclosure includes: A wafer stage cooling system for cooling a wafer stage (4, 4A) that supports a semiconductor wafer (3) to be plasma etched, comprising: a first cooling device (10, 10A) configured to circulate a first refrigerant (R1); a heat exchanger (9) configured to perform heat exchange between the first refrigerant and a second refrigerant (R2); a heat pipeline (30, 30A) in which the second refrigerant is sealed and which circulates between the heat exchanger and the wafer stage; Equipped with The heat pipeline is a condensation section (31) for condensing the second refrigerant from a gas phase to a liquid phase by heat exchange with the first refrigerant; an evaporation section (32) for evaporating the second refrigerant in the liquid phase through cooling the wafer stage; at least one circulation line (35, 35A) for circulating the second refrigerant between the condenser section and the evaporator section; Includes.

[0056] According to the configuration of 1) above, the second refrigerant cooled by the first cooling device is supplied to the wafer stage, thereby cooling the wafer stage. The heat pipeline circulates the second refrigerant without the need for a power source such as a pump, fan, or blower, simplifying the configuration of the wafer stage cooling system. Furthermore, the heat pipeline transports heat at high speed by repeatedly evaporating and condensing the second refrigerant, enabling efficient cooling of the wafer stage. This achieves a wafer stage cooling system that can efficiently cool the wafer stage with a simple configuration. Furthermore, because the second refrigerant changes from a liquid phase to a gas phase in the evaporator, the amount of heat exchange between the wafer stage and the second refrigerant is stabilized, allowing the temperature of the wafer stage to be kept within a desired range.

[0057] 2) In some embodiments, the wafer stage cooling system described in 1) above, the condensation section is located vertically above the evaporation section, The heat pipeline is a thermosiphon type heat pipe in which the second refrigerant in the liquid phase moves from the condenser to the evaporator by its own weight.

[0058] According to the above configuration 2), the configuration of the heat pipeline can be further simplified compared to a heat pipe of the type in which a wick is provided inside the circulation line.

[0059] 3) In some embodiments, the wafer stage cooling system according to 1) or 2) above, Each of the at least one circulation line comprises: a single piping line (36) connecting the condenser section and the evaporator section; The single piping line defines a liquid-phase flow path of the second refrigerant from the condenser to the evaporator, and also defines a vapor-phase flow path of the second refrigerant from the evaporator to the condenser.

[0060] According to the above configuration 3), the configuration of the heat pipeline can be further simplified compared to when the liquid phase flow path and the gas phase flow path are formed in two different piping lines.

[0061] 4) In some embodiments, the wafer stage cooling system according to any one of 1) to 3) above, The evaporation section is an internal flow path (5) formed inside the wafer stage.

[0062] According to the configuration of 4) above, the second refrigerant changes from a liquid state to a gas state while flowing through the internal flow path of the wafer stage, which allows the wafer stage to be cooled more uniformly.

[0063] 5) In some embodiments, the wafer stage cooling system described in 4) above, The internal flow path is formed in a spiral shape in a plan view, the at least one circulation line includes a plurality of the piping lines; The plurality of piping lines are connected to the internal flow path at positions different from each other in a plan view.

[0064] According to the above configuration 5), the second refrigerant is supplied in liquid phase to the internal flow path at multiple positions, which causes the second refrigerant to evaporate more evenly in the internal flow path, thereby enabling the wafer stage to be cooled more uniformly.

[0065] 6) In some embodiments, the wafer stage cooling system according to 4) or 5) above, The wafer stage is a mounting portion (41) on which the semiconductor wafer is mounted; a heat sink portion (42) that supports the mounting portion and has higher heat dissipation properties than the mounting portion; Including, The internal flow path is formed inside the heat sink portion.

[0066] In a mounting part that has functions such as accommodating an electrode part for etching processing in addition to supporting a semiconductor wafer, there are significant design constraints for arranging internal flow paths. In this regard, according to the configuration of 6) above, the internal flow paths are formed in the heat sink part that supports the mounting part, so that the internal flow paths can be arranged according to the amount of heat required for cooling the semiconductor wafer.

[0067] 7) In some embodiments, the wafer stage cooling system according to any one of 1) to 6) above, a liquefied gas line (45) through which liquefied gas flows to be used as a process gas in a semiconductor factory; The heat exchanger is configured to cool the second refrigerant by heat exchange between the liquefied gas as a third refrigerant and the second refrigerant.

[0068] According to the above configuration 7), the second refrigerant can be cooled using cold energy recovered from the liquefied gas used in the semiconductor factory, so that the cooling load of the first cooling device can be reduced.

[0069] 8) In some embodiments, the wafer stage cooling system according to any one of 1) to 7) above, The first cooling device is a first refrigerant circulation line (11) through which the first refrigerant circulates; a compressor (12), an expansion turbine (13), and a heat exchanger (14) arranged on the first refrigerant circulation line; Including, The heat exchange unit is configured to introduce the expanded first refrigerant discharged by the expansion turbine into the heat exchanger.

[0070] According to the configuration of 8) above, the first refrigerant at a very low temperature expanded in the expansion turbine is introduced into the heat exchange section, thereby making it possible to sufficiently lower the temperature of the second refrigerant in a liquid phase in the heat exchange section.

[0071] 9) In some embodiments, the wafer stage cooling system described in 8) above, a liquefied gas line (45) through which liquefied gas flows to be used as a process gas in a semiconductor factory; a cooling heat exchanger (48) configured to cool the first refrigerant by heat exchange between the first refrigerant flowing from the expansion turbine toward the heat exchange section and the liquefied gas flowing through the liquefied gas line; Further provided are:

[0072] According to the above configuration 9), the second refrigerant flowing from the expansion turbine toward the heat exchange section is cooled by the liquefied gas, so that the cooling load of the first cooling device can be reduced.

[0073] 10) In some embodiments, the wafer stage cooling system according to 8) or 9) above, The first cooling device is configured so that the first refrigerant is maintained in a gas phase and circulates through the first refrigerant circulation line.

[0074] According to the above configuration 10), a liquid refrigerant such as an organic fluorine compound or a fluorine-based inert liquid is not used as the first refrigerant, which reduces the environmental impact and allows the temperature of the first refrigerant flowing into the heat exchange section to be extremely low.

[0075] 11) The wafer stage cooling system (2) according to at least one embodiment of the present disclosure includes: A wafer stage cooling system for cooling a wafer stage (4) that supports a semiconductor wafer (3) to be plasma etched, comprising: a first cooling device (210) including a first compressor (211) for compressing a first refrigerant, a first expansion valve (231) for expanding the first refrigerant, and a plurality of first heat exchangers (241) for exchanging heat between the first refrigerant guided from the first compressor to the first expansion valve and the first refrigerant guided from the first expansion valve to the first compressor; a second cooling device (220, 220A) for cooling the wafer stage using a second refrigerant cooled by the first refrigerant; Equipped with The second cooling device is a second expansion valve (222) for expanding the second refrigerant; an internal flow path (5) formed inside the wafer stage for evaporating the second refrigerant; a liquid supply line (225) for supplying the second refrigerant in a liquid phase discharged from the second expansion valve to the internal flow path; a gas return line (226, 226A) for returning the second refrigerant in a gas phase state discharged from the internal flow path to the second expansion valve; Including, The gas return line is configured to pass the second refrigerant through each of the plurality of first heat exchangers.

[0076] According to the above configuration 11), the Claude cycle is adopted in the first cooling device, so that the cooling efficiency of the first cooling device can be improved.

[0077] 12) In some embodiments, the wafer stage cooling system described in 11) above, the second cooling device further includes a blower (228) disposed on the gas return line; The gas return line a first gas return line (226, 226A) for guiding the second refrigerant from the internal flow path to the blower; a second gas return line (226, 226A) for guiding the second refrigerant from the blower to the second expansion valve and for passing the second refrigerant through each of the plurality of first heat exchangers; and The wafer stage cooling system further includes a second heat exchanger (242) for exchanging heat between the second refrigerant flowing through the first gas return line and the first refrigerant flowing from the first expansion valve toward the first compressor.

[0078] According to the above configuration 12), the second refrigerant is cooled by the first refrigerant not only in the second gas return line but also in the first gas line, thereby making it possible to extremely reduce the temperature of the second refrigerant. [Explanation of symbols]

[0079] 1: Semiconductor factory 2: Wafer stage cooling system 3: Semiconductor wafer 4, 4A: Wafer stage 5: Internal flow path 6: Plasma processing equipment 7: Chamber 8: Gas shower head 9: Heat exchanger 10,10A: 1st cooling device 11: First refrigerant circulation line 12a, 12b, 12c(12): Compressor 13: Expansion turbine 14:Heat exchange section 15a, 15b: Motor 17: 1st heat exchanger 18:Second heat exchanger 29: Heat sink 30,30A: Heat pipeline 31: Condenser section 32: Evaporation section 35, 35A: Circulation line 36:Pipe line 41: Placement section 42: Heat sink part 45: Liquefied gas line 47: Storage tank 48: Cooling heat exchanger 111: Refrigerant supply line 112: Refrigerant return line 121: Compressor 122: Evaporator 123: Capacitor 128: Phase separator 129,131,132: Heat exchanger 133: Power source 150: Cold energy utilization line 201, 201A: Wafer stage cooling system 203: First refrigerant circulation line 210: 1st cooling device 211: First compressor 218: Supply line 219: Return line 220,220A: 2nd cooling device 222: Second expansion valve 225: Liquid supply line 226, 226A: Gas return line 227:Warmer 228: Blower 230: Expansion turbine 231: First expansion valve 241: 1st heat exchanger 242:Second heat exchanger 243 :Heat exchanger 261: First gas return line 262: Second gas return line 351: First piping line 352: Second piping line R1: First refrigerant R2:Second refrigerant R3: Third refrigerant R4: Fourth refrigerant

Claims

1. 1. A wafer stage cooling system for cooling a wafer stage that supports a semiconductor wafer to be plasma etched, comprising: a first cooling device configured to circulate a first refrigerant; a heat exchanger configured to perform heat exchange between the first refrigerant and a second refrigerant; a heat pipeline containing the second refrigerant and circulating between the heat exchanger and the wafer stage; Equipped with The heat pipeline is a condensation section for condensing the second refrigerant from a gas phase state to a liquid phase state by heat exchange with the first refrigerant; an evaporation section for evaporating the second refrigerant in the liquid phase through cooling the wafer stage; at least one circulation line for circulating the second refrigerant between the condenser and the evaporator; Contains Wafer stage cooling system.

2. the condensation section is located vertically above the evaporation section, The heat pipeline is a thermosiphon type heat pipe in which the second refrigerant in the liquid phase moves from the condenser to the evaporator by its own weight.

2. The wafer stage cooling system according to claim 1.

3. Each of the at least one circulation line comprises: a single piping line connecting the condenser and the evaporator; The single piping line defines a liquid-phase flow path of the second refrigerant from the condenser to the evaporator, and also defines a vapor-phase flow path of the second refrigerant from the evaporator to the condenser.

3. The wafer stage cooling system according to claim 1.

4. The evaporation section is an internal flow path formed inside the wafer stage.

3. The wafer stage cooling system according to claim 1.

5. The internal flow path is formed in a spiral shape in a plan view, the at least one circulation line includes a plurality of the piping lines; The plurality of piping lines are connected to the internal flow path at different positions in a plan view.

5. The wafer stage cooling system according to claim 4.

6. The wafer stage is a mounting portion on which the semiconductor wafer is mounted; a heat sink portion that supports the mounting portion and has a higher heat dissipation capability than the mounting portion; Including, The internal flow path is formed inside the heat sink portion.

5. The wafer stage cooling system according to claim 4.

7. further comprising a liquefied gas line through which liquefied gas flows to be used as a process gas in the semiconductor factory; The heat exchanger is configured to cool the second refrigerant by heat exchange between the liquefied gas as a third refrigerant and the second refrigerant.

3. The wafer stage cooling system according to claim 1.

8. The first cooling device is a first refrigerant circulation line for circulating the first refrigerant; a compressor, an expansion turbine, and a heat exchange unit disposed on the first refrigerant circulation line; Including, The heat exchange unit is configured to introduce the expanded first refrigerant discharged by the expansion turbine into the heat exchanger.

3. The wafer stage cooling system according to claim 1.

9. A liquefied gas line through which liquefied gas flows to be used as a process gas in semiconductor factories; a cooling heat exchanger configured to cool the first refrigerant by heat exchange between the first refrigerant flowing from the expansion turbine toward the heat exchange unit and the liquefied gas flowing through the liquefied gas line; Further equipped 9. The wafer stage cooling system according to claim 8.

10. The first cooling device is configured so that the first refrigerant is maintained in a gas phase and circulates through the first refrigerant circulation line.

9. The wafer stage cooling system according to claim 8.

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