JP2005207662A - Extremely low temperature refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extremely low temperature refrigerating device with a cooler which gets to an extremely low temperature level in a short time without impairing its cooling performance by improving the circuit construction of a pressure reducer. <P>SOLUTION: First and second branch circuits 80, 81 connected in parallel to each other are formed on the midway of a main refrigerant circuit 2a connected to a discharge portion on the primary side of a supercooler 47. A cryo-coil 52 is connected in series to the main refrigerant circuit 2a on the downstream side of a combination portion of both branch circuits 80, 81. A first branch capillary tube 80a is connected in series to the first branch circuit 80, while a solenoid on-off valve 81b and a second capillary tube 81a are connected at their upstream sides in series to the second branch circuit 81. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultra-low temperature refrigeration apparatus that generates cold at an ultra-low temperature level, and more particularly to a circuit configuration of a decompression means for decompressing a refrigerant that reaches a cooler.

  Conventionally, for example, as disclosed in Patent Document 1, a mixed refrigerant composed of several kinds of refrigerants having different boiling point temperatures is sequentially condensed from a refrigerant having a high boiling point temperature to a refrigerant having a low boiling point temperature. A so-called mixed refrigerant type ultra-low temperature refrigeration apparatus is known in which a refrigerant having an evaporating temperature is finally evaporated to obtain a desired ultra-low temperature. This type of ultra-low temperature refrigeration apparatus is installed, for example, in a vacuum chamber of a vacuum film forming apparatus used for manufacturing a wafer or the like, and is used to capture a gas in the vacuum chamber and raise a vacuum level.

In such an ultra-low temperature refrigeration apparatus, a mixed refrigerant is connected to a refrigerant circuit including a compressor, a condenser, a multi-stage gas-liquid separator and a cascade heat exchanger, a decompressor, and a cooler (evaporator). It comes to circulate. And after condensing mainly high boiling point refrigerant in the condenser, it is separated into liquid refrigerant and gas refrigerant in the first stage gas-liquid separator, and on the primary side of the first stage cascade heat exchanger, The gas refrigerant and the liquid refrigerant decompressed after being separated are heat-exchanged and cooled. In the second and subsequent cascade heat exchangers, heat exchange is performed in the same manner, and the liquid refrigerant flowing out from the primary side of the final stage cascade heat exchanger is depressurized by the decompressor, and the low-boiling-point refrigerant in the cooler By evaporating, ultra-low temperature level of cold is supplied. Further, the refrigerant cooled by this cooler is returned to the secondary side of the final stage cascade heat exchanger and returned to the compressor while passing through the secondary side of the cascade heat exchanger of each stage. Yes.
JP-A-6-347112

  By the way, in the said ultra-low temperature freezing apparatus, it is requested | required that a cooler should be cooled from normal temperature to an ultra-low temperature level for a short time, for example, the operating rate of a vacuum film-forming apparatus can be improved, and it is preferable. Here, when a capillary tube is used as the pressure reducer, if the total length of the capillary tube is shortened to reduce the channel resistance, the cooler can be cooled to a low temperature level in a short time, and the above requirement is satisfied. However, on the other hand, it has been difficult to secure a cooling capacity for cooling to a predetermined cooling temperature.

  On the other hand, if the capillary tube length is increased by increasing the overall length of the capillary tube, the refrigerant can be decompressed to an evaporation pressure corresponding to the evaporation temperature of the low boiling point refrigerant, and the object to be cooled can be cooled to an ultra-low temperature level. The resistance loss increases, and it becomes difficult to cool rapidly in a short time.

  As described above, in the circuit configuration of the conventional pressure reducer, it is difficult to cool the cooler to an ultra-low temperature level in a short time.

  The present invention has been made in view of such points, and an object of the present invention is to improve the circuit configuration of the decompressor in the ultra-low temperature refrigeration apparatus, so that the cooler can be used for a short time without impairing the cooling capacity. It is to be able to cool to an ultra-low temperature level.

  In order to achieve the above object, the present invention provides a branch decompression unit connected to each of the plurality of branch circuits in which refrigerant circuits reaching the cooler are connected in parallel to each other, and selectively distributes the refrigerant to the plurality of branch decompression units. I tried to make it.

That is, the invention of claim 1 is a compressor that compresses a mixed refrigerant obtained by mixing a plurality of types of refrigerants having different boiling points,
A condenser that cools and liquefies a high boiling point refrigerant among the mixed refrigerant discharged from the compressor;
A multi-stage gas-liquid separator that sequentially separates the mixed refrigerant liquefied by the condenser from a high boiling point refrigerant into a low boiling point refrigerant into a liquid refrigerant and a gas refrigerant;
A plurality of stages in which the primary-side gas refrigerant separated by each gas-liquid separator is cooled by heat exchange with the secondary-side liquid refrigerant separated and decompressed by each gas-liquid separator. A cascade heat exchanger,
Decompression means for decompressing the low-boiling point refrigerant flowing out from the primary side of the cascade heat exchanger at the final stage of the plurality of stages;
In the ultra-low temperature refrigeration apparatus in which a low-boiling point refrigerant depressurized by the depressurizing means is connected by a refrigerant circuit to a cooler that cools an object to be cooled to an ultra-low temperature level,
The refrigerant circuit for supplying the refrigerant from the primary side of the final stage cascade heat exchanger to the cooler includes a plurality of branch circuits connected in parallel to each other.
The decompression means comprises a plurality of branch decompression means connected in series to each of the plurality of branch circuits,
Switching means for switching the refrigerant to flow through at least one of the plurality of branch circuits is provided.

  Therefore, according to the present invention, the branch pressure reducing means is connected to each of the plurality of branch circuits connected in parallel to each other, and the switching means for switching so that the refrigerant flows through at least one of the plurality of branch circuits. Therefore, by switching the switching means, the refrigerant can be branched into a plurality of branch circuits to increase the circulation amount. Therefore, it is possible to shorten the cooling time until the cooling temperature is reached while securing the cooling capacity for cooling the cooling target to the predetermined cooling temperature by increasing the flow path resistance of the refrigerant.

The invention of claim 2 is the ultra-low temperature refrigeration apparatus according to claim 1,
The switching means is an on-off valve provided in at least one of the plurality of branch circuits.

  Therefore, according to the present invention, by selectively opening the on-off valve, it is possible to adjust the flow rate of the refrigerant that branches into the plurality of branch circuits. Thereby, the cooling temperature and cooling time in a cooler can be adjusted arbitrarily.

The invention of claim 3 is the ultra-low temperature refrigeration apparatus according to claim 1 or 2,
The plurality of branch pressure reducing means have different pressure reducing capabilities.

  Therefore, according to the present invention, since the plurality of branch pressure reducing units have different pressure reducing capabilities, the cooling temperature in the cooler is compared with the case where the plurality of branch pressure reducing units have the same pressure reducing capability. And the adjustment range of cooling time can be enlarged.

The invention of claim 4 is the ultra-low temperature refrigeration apparatus according to any one of claims 1 to 3,
The branch pressure reducing means is a capillary tube.

  Therefore, according to the present invention, by using the capillary tube as the branch pressure reducing means, the low boiling point refrigerant can be reliably decompressed even in the ultra-low temperature region. Thereby, for example, the reliability is higher than in the case where an expansion valve or the like is used as the pressure reducing means, which is advantageous in stably operating the apparatus. In addition, since the capillary tube is less expensive than the expansion valve, the facility cost can be greatly reduced.

  As described above, according to the invention according to claim 1, the refrigerant circuit for supplying the refrigerant to the cooler from the primary side of the cascade heat exchanger at the final stage of the ultra-low temperature refrigeration apparatus is branched into a plurality of parts. By connecting the decompression means to the branch circuit and switching the switching means, the refrigerant can be branched into a plurality of branch circuits to increase the circulation amount, and the cooling capacity for cooling the object to be cooled to a predetermined cooling temperature is ensured. It is possible to shorten the cooling time until the cooling temperature is reached.

  According to the invention which concerns on Claim 2, the cooling temperature and cooling time in a cooler can be arbitrarily adjusted with the on-off valve provided in at least one of the branch circuits.

  According to the invention which concerns on Claim 3, the adjustment range of the cooling temperature and cooling time in a cooler can be enlarged further.

  According to the invention according to claim 4, it is possible to reliably perform the pressure reducing operation even in the ultra-low temperature region, which is advantageous for stable operation of the apparatus, leading to improvement of reliability, and greatly reducing the equipment cost. Is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its application.

<Embodiment 1>
FIG. 1 shows an example of a layout of a vacuum film-forming apparatus A according to an embodiment of the present invention. Reference numeral 120 denotes a vacuum chamber in which a wafer (not shown) is formed by keeping the inside in a vacuum state. A loading / unloading port (not shown) opened and closed by an opening / closing door 123 is opened at 120, and a wafer to be deposited is loaded into the vacuum chamber 120 or deposited with the opening / closing door 123 opened. The subsequent wafer is unloaded from the vacuum chamber 120. A vacuum pump 121 is connected to the vacuum chamber 120 via a communication passage 122, and a gate valve 124 is provided at a connection portion of the communication passage 122 with the vacuum chamber 120 to switch between the two to open or close. The vacuum chamber 120 is evacuated by the operation of the vacuum pump 121 with the open / close door 123 closed and the gate valve 124 opened.

  The vacuum film forming apparatus A is provided with an ultra-low temperature refrigeration apparatus 10 constituting the refrigeration system of the present invention, and a vacuum coil 121 of the vacuum pump 121 is evacuated by a cryocoil (cooler) 52 described later of the ultra-low temperature refrigeration apparatus 10. In this state, the gas and moisture to be cooled in the vacuum chamber 120 are directly cooled to an ultra-low temperature level so that the gas and the like are captured and the vacuum level in the vacuum chamber 120 is raised.

  On the other hand, FIG. 2 shows another example of the layout of the vacuum film-forming apparatus A. The cryocoil 52 of the refrigeration apparatus 10 is disposed not in the vacuum chamber 120 but in the middle of the communication path 122 and is formed by the vacuum pump 121. The vacuum level in the vacuum chamber 120 is increased by cooling and capturing the gas and moisture in the communication path 122, that is, indirectly the gas and moisture in the vacuum chamber 120 by the ultra-low temperature refrigeration apparatus 10 in a vacuum state. I have to. The other structure is the same as that of the vacuum film forming apparatus A shown in FIG.

  The ultra-low temperature refrigeration apparatus 10 generates refrigeration at an ultra-low temperature level of −100 ° C. or lower by using a non-azeotropic refrigerant mixture obtained by mixing five or six refrigerants having different boiling temperatures as refrigerants.

  FIG. 3 shows the overall configuration of the ultra-low temperature refrigeration apparatus 10. Reference numeral 1 denotes a closed cycle refrigerant circuit in which the mixed refrigerant is enclosed. The refrigerant circuit 1 is formed by connecting various devices described below through refrigerant piping. A compressor 20 compresses the gas refrigerant, and a first oil separator 15 is connected to a discharge portion of the compressor 20. The first oil separator 15 separates the compressor lubricating oil mixed in the gas refrigerant discharged from the compressor 20 from the gas refrigerant, and the separated lubricating oil is supplied to the oil return pipe. 18 is returned to the suction side of the compressor 20. A water-cooled condenser 21 is connected to the refrigerant discharge portion of the first oil separator 15 to cool and condense the gas refrigerant discharged from the compressor 20 by heat exchange with the cooling water in the cooling water passage 11. The discharge side of the water-cooled condenser 21 is connected to the primary side of the auxiliary condenser 22 via a dryer 17 that removes moisture and contamination in the refrigerant. In the auxiliary condenser 22, the gas refrigerant from the water-cooled condenser 21 is supplied. It cools and condenses by exchanging heat with the low-temperature secondary reflux refrigerant sucked into the compressor 20. In this embodiment, the water-cooled condenser 21 and the auxiliary condenser 22 constitute a condenser, and both the condensers 21 and 22 condense and liquefy the gas refrigerant having the highest boiling point temperature among the mixed refrigerants. It has become.

  A first gas-liquid separator 24 is connected to a primary-side discharge portion of the auxiliary capacitor 22, and the gas-liquid mixed refrigerant from the auxiliary capacitor 22 is converted into a liquid refrigerant and a gas by the first gas-liquid separator 24. Separated into refrigerant. The primary side of the cascade-type first heat exchanger 25 is provided in the gas refrigerant discharge portion of the first gas-liquid separator 24, and the same is provided in the liquid refrigerant discharge portion via the first capillary tube 26 as decompression means. The secondary side of the first heat exchanger 25 is connected to each other, and after the liquid refrigerant separated by the first gas-liquid separator 24 is decompressed by the first capillary tube 26, the secondary side of the first heat exchanger 25 is The gas refrigerant on the primary side is cooled by this evaporation, and the gas refrigerant having the second highest boiling point temperature in the mixed refrigerant is condensed and liquefied.

  Further, a second gas-liquid separator 30 is connected to the primary discharge section of the first heat exchanger 25, and the gas from the first heat exchanger 25 is connected to the second gas-liquid separator 30. The liquid mixed refrigerant is separated into a liquid refrigerant and a gas refrigerant. The gas refrigerant discharge part of the second gas-liquid separator 30 is the same as the primary side of the cascade-type second heat exchanger 31, and the liquid refrigerant discharge part is the same through a second capillary tube 32 as decompression means. The secondary side of the second heat exchanger 31 is connected to each other, and after the liquid refrigerant separated by the second gas-liquid separator 30 is decompressed by the second capillary tube 32, the secondary side of the second heat exchanger 31. The gas refrigerant on the primary side is cooled by this evaporation, and the gas refrigerant having the third highest boiling point temperature in the mixed refrigerant is condensed and liquefied.

  Further, in the same manner as in the connection structure, a third gas-liquid separator 36, a third heat exchanger 37, and a third capillary tube 38 are also provided at the primary discharge portion of the second heat exchanger 31. A fourth gas-liquid separator 42, a fourth heat exchanger 43, and a fourth capillary tube 44 are connected to the discharge section on the primary side in the third heat exchanger 37 (these connection structures are described above). Since it is the same as the connection structure of the first gas-liquid separator 24, the first heat exchanger 25, and the first capillary tube 26, detailed description thereof is omitted), and the liquid separated by the third gas-liquid separator 36 After the refrigerant is decompressed by the third capillary tube 38, the refrigerant is supplied to the secondary side of the third heat exchanger 37 and evaporated, and the gas refrigerant on the primary side is cooled by the evaporation. The fourth highest temperature gas refrigerant is condensed While being liquefied, the liquid refrigerant separated by the fourth gas-liquid separator 42 is decompressed by the fourth capillary tube 44 and then supplied to the secondary side of the fourth heat exchanger 43 to evaporate. The gas refrigerant on the side is cooled by heat exchange, and the gas refrigerant having the lowest boiling point temperature among the mixed refrigerants is condensed and liquefied.

  And the primary side of the subcooler (subcooler) 47 which consists of a heat exchanger is connected to the primary side discharge part in the said 4th heat exchanger 43, and the primary side discharge part of this subcooler 47 The refrigerant circuit connected to is branched into a main refrigerant circuit 2a and a sub refrigerant circuit 2b on the way.

  A fifth capillary tube 48 is connected in the middle of the sub refrigerant circuit 2b. The downstream end of the sub refrigerant circuit 2b is connected to the secondary side of the same supercooler 47, and the secondary side of the subcooler 47 is connected to the secondary side of the fourth heat exchanger 43 via the refrigerant circuit. After the refrigerant discharged from the fourth heat exchanger 43 is connected to the primary side of the subcooler 47, a part of the refrigerant is decompressed by the fifth capillary tube 48 of the sub refrigerant circuit 2b. The liquid refrigerant is supplied to the secondary side of the subcooler 47 to evaporate, and the primary side gas refrigerant is cooled by the heat of evaporation.

  Next, features of the present invention will be described. The middle of the main refrigerant circuit 2a is branched into first and second branch circuits 80 and 81 connected in parallel to each other, and the main refrigerant circuit on the downstream side of the downstream end joining portion of both the branch circuits 80 and 81. A cryocoil 52 is connected in series to 2a.

  A first branch capillary tube 80 a is connected to the first branch circuit 80 in series. The second branch circuit 81 is connected in series with an electromagnetic on-off valve 81b and a second branch capillary tube 81a in series from the upstream side. Here, the electromagnetic on-off valve 81b constitutes switching means for switching so that the refrigerant is supplied to the second branch circuit 81. In addition, capillary tubes having different decompression capacities are used for the first and second branch capillary tubes 80a and 81a.

  The cryocoil 52 constitutes a main cooler. As shown in FIG. 1 or FIG. 2, the cryocoil 52 cools a gas or moisture as a cooling target in the vacuum chamber 120. The downstream end of the main refrigerant circuit 2 a is connected to the refrigerant circuit between the secondary side of the fourth heat exchanger 43 and the secondary side of the subcooler 47, and from the primary side of the subcooler 47. The remaining portion of the discharged refrigerant is decompressed by the first branch capillary tube 80a or the first and second branch capillary tubes 80a, 81a, then supplied to the cryocoil 52 and evaporated, and the heat of evaporation causes a vacuum chamber. The gas and moisture (cooling target) in 120 are cooled to an ultralow temperature level of −100 ° C. or lower, and the gas and moisture are captured to increase the vacuum level.

  In addition, the secondary side (and the cryocoil 52) of the supercooler 47, the fourth heat exchanger 43, the third heat exchanger 37, the second heat exchanger 31, the first heat exchanger 25, and the auxiliary condenser 22 are used. Are connected in series in the order of description by the refrigerant circuit, the secondary side of the auxiliary capacitor 22 is connected to the suction side of the compressor 20, and the refrigerant gasified by evaporation in the mixed refrigerant is compressed into the compressor. 20 is inhaled.

  The cryocoil 52 is arranged in the vacuum chamber 120 so that the gas in the vacuum chamber 120 is directly cooled by the cryocoil 52. However, instead of the cryocoil 52, a brine cooler is provided, The brine cooler is connected to the heat absorption part located in the vacuum chamber 120 by a brine circuit, and in this brine cooler, the brine in the brine circuit is cooled to an ultra-low temperature level, and the same temperature level is applied to the heat absorption part in the vacuum chamber 120 by the brine. You may make it provide the cold of.

  The condensers 21 and 22, the heat exchangers 25, 31, 37, and 43 and the supercooler 47 may be any of a double tube structure, a plate structure, and a shell and tube structure. Further, instead of the capillary tubes 26, 32, 38, 44, other decompression means such as an expansion valve can be used.

  In FIG. 3, reference numeral 60 denotes a defrost circuit that supplies the high-temperature gas refrigerant (hot gas) discharged from the compressor 20 to the cryocoil 52 as it is, and is provided between the first oil separator 15 and the water-cooled condenser 21. The refrigerant circuit is connected to the main refrigerant circuit 2 a between the junction of the first and second branch circuits 80 and 81 and the cryocoil 52. 61 is an electromagnetic on-off valve connected in the middle of the defrost circuit 60, 62 is a downstream of the defrost circuit 60 in the main refrigerant circuit 2a between the junction of the first and second branch circuits 80 and 81 and the cryocoil 52. It is an electromagnetic on-off valve connected to the upstream side (the first and second branch circuits 80 and 81 side) from the connection position with the end.

  A second oil separator 16 that separates compressor lubricating oil from gas refrigerant is disposed between the upstream end of the defrost circuit 60 and the electromagnetic on-off valve 61. The lubricating oil separated by the second oil separator 16 is returned to the suction side of the compressor 20 through the oil return pipe 18 in the same manner as the first oil separator 15.

  When the vacuum chamber 120 of the vacuum film forming apparatus A shown in FIG. 1 is in a vacuum state to perform film formation on a wafer, the defrost circuit 60 is closed by opening the electromagnetic opening / closing valve 61 and the electromagnetic opening / closing valve 62 is opened. By opening the main refrigerant circuit 2a, the cryocoil 52 evaporates the low boiling point refrigerant and cools and captures the gas and moisture in the vacuum chamber 120, while opening the open / close door 123 and forming the wafer in the vacuum chamber 120. At the time of the defrost operation in a state where no film is formed, the defrost circuit 60 is opened by opening the electromagnetic on-off valve 61 and the main refrigerant circuit 2a is closed by closing the electromagnetic on-off valve 62, thereby The gas refrigerant (hot gas) is supplied to the cryocoil 52 through the defrost circuit 60 as it is, and the trapping of gas or the like in the cryocoil 52 is returned. Unishi to have.

  Reference numeral 65 denotes a buffer tank for preventing an abnormal increase in the discharge pressure of the compressor 20 due to insufficiently condensed gas refrigerant at the start of operation of the cryogenic refrigeration apparatus 10. Further, the vicinity of the electromagnetic on-off valve 61 of the defrost circuit 60, the vicinity of the electromagnetic on-off valve 62 between the junction of the first and second branch circuits 80, 81 and the cryocoil 52, the outlet side of the cryocoil 52, and the first First to third manual on-off valves 71, 72, and 73 are arranged in the refrigerant circuit between the secondary side of the four heat exchanger 43. These first to third manual opening / closing valves 71, 72, 73 are closed when the cryocoil 52 is replaced or maintained, so that the mixed refrigerant remaining in the circuit does not leak to the outside. .

  Further, a refrigerant supply line 70 for supplying a mixed refrigerant into the refrigerant circuit 1 of the cryogenic refrigeration apparatus 10 is provided in the refrigerant pipe between the outlet side of the cryocoil 52 and the secondary side of the fourth heat exchanger 43. Is connected. The refrigerant supply pipe 70 also serves as a discharge pipe for discharging the mixed refrigerant from the refrigerant circuit 1. The refrigerant supply pipe 70 is provided with a supply opening / closing valve 75 that opens when the refrigerant is supplied or discharged.

  In the embodiment configured as described above, when a wafer is formed in the vacuum chamber 120 of the vacuum film forming apparatus A, the ultra-low temperature refrigeration apparatus 10 is operated and the inside of the vacuum chamber 120 (or the communication path 122). The gas is cooled to an ultralow temperature level of −100 ° C. or lower and captured, and the vacuum chamber 120 is evacuated. That is, during operation of the cryogenic refrigeration apparatus 10, the defrost circuit 60 is closed by closing the electromagnetic on-off valve 61 and the main refrigerant circuit 2 a is opened by opening the electromagnetic on-off valve 62. Further, the second branch circuit 81 is opened by opening the electromagnetic on-off valve 81b. As a result, the mixed refrigerant discharged from the compressor 20 is cooled by the water-cooled condenser 21 and then cooled by the secondary-side refrigerant returned to the compressor 20 by the auxiliary condenser 22, and the boiling point of the mixed refrigerant has the highest temperature. The gas refrigerant is condensed and liquefied. This refrigerant is separated into a gas refrigerant and a liquid refrigerant in the first gas-liquid separator 24, and the liquid refrigerant evaporates on the secondary side of the first heat exchanger 25 after being depressurized by the first capillary tube 26. The gas refrigerant from the first gas-liquid separator 24 is cooled by heat, and the gas refrigerant having the second highest boiling point temperature in the mixed refrigerant is condensed and liquefied. Thereafter, in the same manner, in the second to fourth heat exchangers 31, 37, 43, the gas refrigerant is condensed and liquefied in order from the highest boiling point temperature of the mixed refrigerant. The gas refrigerant having the lowest boiling point temperature is condensed and liquefied.

  The refrigerant discharged from the primary side of the fourth heat exchanger 43 is in a gas-liquid mixed state, and the gas-liquid mixed refrigerant passes through the primary side of the subcooler 47 and then the main refrigerant circuit 2a and the sub refrigerant. The circuit 2b is separated. The refrigerant flowing into the sub refrigerant circuit 2b is decompressed by the fifth capillary tube 48 and then supplied to the secondary side of the supercooler 47 to evaporate, and this evaporative heat causes supercooling from the fourth heat exchanger 43. The gas-liquid mixed refrigerant supplied to the primary side of the vessel 47 is further cooled.

  The remaining refrigerant in the gas-liquid mixed state that flows into the main refrigerant circuit 2a after being discharged from the primary side of the subcooler 47 is opened by the electromagnetic on-off valve 81b, and the first and second branch capillary tubes 80a, Each branch is divided into 81a and depressurized. After the depressurization, the cryocoil 52 evaporates and gives cold to the gas and moisture in the vacuum chamber 120. The chilling at a temperature of −100 ° C. or lower traps gas and moisture in the vacuum chamber 120 and raises the vacuum level in the vacuum chamber 120.

  When the detected value detected by a temperature detector or pressure detector (not shown) provided in the ultra-low temperature refrigeration apparatus 10 reaches a preset set temperature (for example, −100 ° C. or lower) or set pressure, an electromagnetic on-off valve 81b is closed and the refrigerant is allowed to flow only through the first branch capillary tube 80a.

  At that time, the flow of the refrigerant is caused by branching the refrigerant to the first and second branch circuits 80 and 81 by opening the electromagnetic on-off valve 81b and reducing the pressure by the first and second branch capillary tubes 80a and 81a, respectively. The amount can be increased. Therefore, by increasing the flow path resistance of the refrigerant, it is possible to shorten the cooling time until reaching the ultra-low temperature level while ensuring the cooling capacity for cooling the object to be cooled to the ultra-low temperature level. As a result, the process time of the film forming process in the vacuum chamber 120 can be shortened and the efficiency can be improved.

  Further, by using the first and second branch capillary tubes 80a and 81a as the decompression means, the refrigerant can be reliably decompressed even in the ultra-low temperature region, as compared with the case where an expansion valve or the like is used as the decompression means. It is highly reliable and is advantageous for stable operation of the apparatus. In addition, since the capillary tube is less expensive than the expansion valve, the facility cost can be greatly reduced.

  On the other hand, during the defrost operation in which the wafer is not formed in the vacuum chamber 120 of the film forming apparatus A, the defrost circuit 60 is opened by opening the electromagnetic opening / closing valve 61 and the electromagnetic opening / closing valve 62 is closed. The refrigerant circuit 2a is closed, whereby the high-temperature gas refrigerant discharged from the compressor 20 is supplied to the cryocoil 52 through the defrost circuit 60, and the capture of gas or the like in the cryocoil 52 is released.

  Next, when the inside of the vacuum chamber 120 is again evacuated after the defrost operation, the defrost circuit 60 is closed by closing the electromagnetic on-off valve 61 and the electromagnetic on-off valve 62 is opened in the same manner as described above. The main refrigerant circuit 2a is opened, and the low-boiling-point refrigerant discharged from the primary side of the subcooler 47 is decompressed by the first and second branch capillary tubes 80a and 81a and evaporated in the cryocoil 52, and the inside of the vacuum chamber 120 Quickly cools from room temperature to ultra-low temperature levels.

  In the present embodiment, in the first to fourth heat exchangers 25, 31, 37, and 43, the refrigerant that goes to the cryocoil 52 is returned to the primary side, and the refrigerant that recirculates from the cryocoil 52 to the compressor 20 is the secondary. In contrast to this, the refrigerant flowing toward the cryocoil 52 may be introduced to the secondary side, and the refrigerant returning from the cryocoil 52 to the compressor 20 may be introduced to the primary side. Of course. Moreover, it is good also as a structure which combined these separately.

  Further, although the capillary tubes having different decompression capacities are used for the first and second branch capillary tubes 80a and 81a, those having the same decompression capability may be used.

  Moreover, although the system which performs gas-liquid separation 4 steps | paragraphs was shown in this embodiment, it replaces with this and this invention is applicable also to the system which performs gas-liquid separation 3 steps | paragraphs or 5 steps or more.

  In the present embodiment, the water cooling system using the water cooling condenser 21 is shown. However, instead of this, a system using an air cooling condenser may be used.

<Embodiment 2>
FIG. 4 is a refrigerant circuit of the ultra-low temperature refrigeration apparatus 10 according to Embodiment 2 of the present invention. Since the difference from the first embodiment is only the circuit configuration of the capillary tube connected between the primary side of the subcooler 47 and the inlet side of the cryocoil 52, the following is the same as in the first embodiment. Are given the same reference numerals and only the differences will be described.

  In other words, in this embodiment, first to fourth branch circuits 80, 81, 82, 83 connected in parallel to each other are formed in the middle of the main refrigerant circuit 2a, and the first to fourth branch circuits 80 are formed. , 81, 82 and 83, a cryocoil 52 is connected in series to the main refrigerant circuit 2 a on the downstream side of the junction.

  Further, a first branch capillary tube 80a is connected to the first branch circuit 80 in series. The second branch circuit 81 includes a first electromagnetic on-off valve 81b and a second branch capillary tube 81a, and the third branch circuit 82 includes a second electromagnetic on-off valve 82b and a second branch capillary. The tube 82a is further connected to the fourth branch circuit 83 in series with a third electromagnetic on-off valve 83b and a fourth branch capillary tube 83a in series from the upstream side. Here, as the first to fourth branch capillary tubes 80a, 81a, 82a, 83a, capillary tubes having different decompression capacities are used. Other configurations are the same as those of the first embodiment.

  In this embodiment, during operation of the ultra-low temperature refrigeration apparatus 10 when a wafer is formed in the vacuum chamber 120 of the vacuum film forming apparatus A, after being discharged from the primary side of the subcooler 47, it is supplied to the main refrigerant circuit 2a. The remaining refrigerant in the flowing gas-liquid mixed state is depressurized by the first branch capillary tube 80a, while the first to third electromagnetic on-off valves 81b, 82b, and 83b are selected so that the object to be cooled can be cooled in a short time. When the valve is opened, the gas is selectively branched into the second to fourth branch capillary tubes 81a, 82a, 83a and depressurized. After the depressurization, the cryocoil 52 evaporates and gas or moisture in the vacuum chamber 120 is evaporated. Gives cold. The chilling at a temperature of −100 ° C. or lower traps gas and moisture in the vacuum chamber 120 and raises the vacuum level in the vacuum chamber 120.

  When the detection value of a temperature detector or pressure detector (not shown) reaches a preset temperature (for example, −100 ° C. or lower) or a preset pressure, for example, first to third electromagnetic on-off valves 81b, 82b, The valve 83b is closed to allow the refrigerant to flow only through the first branch capillary tube 80a.

  Therefore, according to the invention according to the present embodiment, the first to third electromagnetic on-off valves 81b, 82b, 83b are selectively opened to allow the refrigerant to flow through the second to fourth branch capillary tubes 81a, 82a. 83a can be selectively branched, and the cooling temperature in the vacuum chamber 120 and the cooling time to reach the cooling temperature can be arbitrarily adjusted.

  In this embodiment, the main refrigerant circuit 2a has a circuit configuration in which the first to fourth branch circuits 80, 81, 82, and 83 are branched into four circuits. Or a circuit configuration branched into five or more. This also applies to the following fourth embodiment.

<Embodiment 3>
FIG. 5 is a refrigerant circuit of the cryogenic refrigeration apparatus 10 according to Embodiment 3 of the present invention. Since the difference from the first embodiment is only the circuit configuration of the capillary tube connected between the subcooler 47 and the cryocoil 52, the same parts as those in the first embodiment are denoted by the same reference numerals below. Only the differences will be described.

  That is, in the middle of the main refrigerant circuit 2a, the first and second branch circuits 85 and 86 connected in parallel with each other are formed, and the main refrigerant circuit on the downstream side of the junction portion of both the branch circuits 85 and 86 is formed. A cryocoil 52 is connected in series to 2a.

  The first branch circuit 85 includes a first branch capillary tube 85a and a first electromagnetic opening / closing valve 85b, and the second branch circuit 86 includes a second branch capillary tube 86a and a second electromagnetic opening / closing. A valve 86b is connected in series from the upstream side. Here, as the first and second branch capillary tubes 85a and 86a, capillary tubes having different decompression capacities are used. Since the main refrigerant circuit 2a is closed at the time of defrosting by simultaneously closing the first and second electromagnetic on-off valves 85b and 86b, the electromagnetic on-off valve 62 shown in FIG. Yes. Other configurations are the same as those of the first embodiment.

  In this embodiment, during operation of the ultra-low temperature refrigeration apparatus 10 when a wafer is formed in the vacuum chamber 120 of the vacuum film forming apparatus A, after being discharged from the primary side of the subcooler 47, it is supplied to the main refrigerant circuit 2a. The remaining refrigerant in the mixed gas-liquid state is decompressed by branching to the first and second branch capillary tubes 85a and 86a by opening the first and second electromagnetic on-off valves 85b and 86b. The coil 52 evaporates to give cold to the gas and moisture in the vacuum chamber 120. The chilling at a temperature of −100 ° C. or lower traps gas and moisture in the vacuum chamber 120 and raises the vacuum level in the vacuum chamber 120.

  When the detection value detected by a temperature detector or pressure detector (not shown) provided in the ultra-low temperature refrigeration apparatus 10 reaches a preset temperature (for example, −100 ° C. or lower) or a preset pressure, The second electromagnetic opening / closing valves 85b and 86b are closed, and the refrigerant is allowed to flow through only one of the first and second branch capillary tubes 85a and 86a.

  Therefore, according to the invention according to the present embodiment, the first and second electromagnetic on-off valves 85b and 86b are selectively opened to select the refrigerant as the first and second branch capillary tubes 85a and 86a. The cooling temperature in the vacuum chamber 120 and the cooling time to reach the cooling temperature can be arbitrarily adjusted.

  Note that only one of the electromagnetic on / off valves 85b and 86b may be opened without simultaneously opening the first and second electromagnetic on / off valves 85b and 86b.

<Embodiment 4>
FIG. 6 is a refrigerant circuit of the cryogenic refrigeration apparatus 10 according to Embodiment 4 of the present invention. Since the difference from the third embodiment is only the circuit configuration of the capillary tube connected between the subcooler 47 and the cryocoil 52, the same parts as those of the third embodiment are denoted by the same reference numerals below. Only the differences will be described.

  That is, in this embodiment, first to fourth branch circuits 85, 86, 87, 88 connected in parallel to each other are formed in the middle of the main refrigerant circuit 2a, and the first to fourth branch circuits 85 are formed. , 86, 87, 88, the cryocoil 52 is connected in series to the main refrigerant circuit 2a downstream of the junction.

  Further, the first branch circuit 85 has a first branch capillary tube 85a and a first electromagnetic on-off valve 85b, and the second branch circuit 86 has a second branch capillary tube 86a and a second electromagnetic on-off switch. A valve 86b, a third branch circuit 87 with a second branch capillary tube 87a and a third electromagnetic on-off valve 87b, and a fourth branch circuit 88 with a fourth branch capillary tube 88a and a fourth branch tube. Are connected in series with each other from the upstream side. Here, as the first to fourth branch capillary tubes 85a, 86a, 87a, 88a, capillary tubes having different decompression capacities are used. Other configurations are the same as those of the first embodiment.

  In this embodiment, during operation of the ultra-low temperature refrigeration apparatus 10 when a wafer is formed in the vacuum chamber 120 of the vacuum film forming apparatus A, after being discharged from the primary side of the subcooler 47, it is supplied to the main refrigerant circuit 2a. The remainder of the flowing refrigerant in the gas-liquid mixed state is first to third by selectively opening the first to third electromagnetic on-off valves 85b, 86b, 87b, 88b so that the object to be cooled can be cooled in a short time. The fourth branch capillary tubes 85a, 86a, 87a, 88a are selectively branched and depressurized. After the depressurization, the cryocoil 52 evaporates to give cold to the gas and moisture in the vacuum chamber 120. The chilling at a temperature of −100 ° C. or lower traps gas and moisture in the vacuum chamber 120 and raises the vacuum level in the vacuum chamber 120.

  When the detection value of a temperature detector or pressure detector (not shown) provided in the ultra-low temperature refrigeration apparatus 10 reaches a preset temperature (for example, −100 ° C. or lower) or a preset pressure, the first to fourth The electromagnetic on-off valves 85b, 86b, 87b, 88b are closed as appropriate, and the refrigerant is selectively circulated through the first to fourth branch capillary tubes 85a, 86a, 87a, 88a.

  Therefore, according to the invention according to the present embodiment, the first to fourth electromagnetic on-off valves 85b, 86b, 87b, 88b are selectively opened, whereby the refrigerant is supplied to the first to fourth branch capillary tubes 85a. , 86a, 87a, 88a can be selectively branched, and the cooling temperature in the vacuum chamber 120 and the cooling time to reach the cooling temperature can be arbitrarily adjusted.

  As described above, the present invention can increase the circulation amount of the refrigerant by providing a plurality of branch pressure reducing means connected in parallel to the ultra-low temperature refrigeration apparatus and branching the refrigerant to the plurality of branch pressure reducing means. It is extremely useful because it provides a highly practical effect that the cooling time to reach the cooling temperature can be shortened while securing the cooling capacity to cool the object to be cooled to the predetermined cooling temperature. And industrial applicability is high.

It is a schematic explanatory drawing of the vacuum film-forming apparatus which concerns on embodiment of this invention. It is another schematic explanatory drawing of a vacuum film-forming apparatus. It is a refrigerant | coolant system diagram which shows the whole structure of the ultra-low-temperature freezing apparatus which concerns on Embodiment 1 of this invention. FIG. 4 is a view corresponding to FIG. 3 showing Embodiment 2 of the present invention. It is FIG. 3 equivalent view which shows Embodiment 3 of this invention. It is FIG. 3 equivalent view which shows Embodiment 4 of this invention.

Explanation of symbols

10 Ultra-low temperature refrigeration equipment 20 Compressor 21 Water-cooled condenser (condenser)
22 Auxiliary condenser (condenser)
24 1st gas-liquid separator 25 1st heat exchanger 30 2nd gas-liquid separator 31 2nd heat exchanger 36 3rd gas-liquid separator 37 3rd heat exchanger 42 4th gas-liquid separator 43 4th heat Exchanger 52 Cryocoil (cooler)
80 First branch circuit 80a First branch capillary tube 81 Second branch circuit 81a Second branch capillary tube 81b Electromagnetic on-off valve

Claims (4)

A compressor that compresses a mixed refrigerant in which a plurality of types of refrigerants having different boiling points are mixed;
A condenser that cools and liquefies a high boiling point refrigerant among the mixed refrigerant discharged from the compressor;
A multi-stage gas-liquid separator that sequentially separates the mixed refrigerant liquefied by the condenser from a high boiling point refrigerant into a low boiling point refrigerant into a liquid refrigerant and a gas refrigerant;
A plurality of stages in which the primary-side gas refrigerant separated by each gas-liquid separator is cooled by heat exchange with the secondary-side liquid refrigerant separated and decompressed by each gas-liquid separator. A cascade heat exchanger,
Decompression means for decompressing the low-boiling point refrigerant flowing out from the primary side of the cascade heat exchanger at the final stage of the plurality of stages;
In the ultra-low temperature refrigeration apparatus in which a low-boiling point refrigerant decompressed by the decompression means is evaporated to cool a cooling target to an ultra-low temperature level and connected by a refrigerant circuit,
The refrigerant circuit for supplying the refrigerant from the primary side of the final stage cascade heat exchanger to the cooler includes a plurality of branch circuits connected in parallel to each other,
The decompression means comprises a plurality of branch decompression means connected in series to each of the plurality of branch circuits,
An ultra-low temperature refrigeration apparatus comprising switching means for switching so that the refrigerant flows through at least one of the plurality of branch circuits. In the ultra-low temperature refrigeration apparatus according to claim 1,
The ultra-low temperature refrigeration apparatus, wherein the switching means is an on-off valve provided in at least one of the plurality of branch circuits. In the ultra-low temperature refrigeration apparatus according to claim 1 or 2,
The ultra-low temperature refrigeration apparatus, wherein the plurality of branch decompression means have different decompression capabilities. In the ultra-low temperature refrigeration apparatus according to any one of claims 1 to 3,
The ultra-low temperature refrigeration apparatus, wherein the branch decompression means is a capillary tube.

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