WO2002009154A1

WO2002009154A1 - Apparatus for controlling refrigerant temperature in coolers of semiconductor device manufacturing systems

Info

Publication number: WO2002009154A1
Application number: PCT/KR2001/000895
Authority: WO
Inventors: Sung-Joon Yoon; Byung-Chul You; Yong-Eun Hong; Hyun-Gu Kang
Original assignee: Fine Semitech Co., Ltd.
Priority date: 2000-07-20
Filing date: 2001-05-28
Publication date: 2002-01-31
Also published as: KR20000059181A; AU2001260764A1; KR100337575B1

Abstract

The object of this invention is to provide an apparatus for controlling the refrigerant temperature I n the cooler of a semiconductor device manufacturing system. This apparatus controls the supply of process cooling water in accordance with the temperatures of inlet and outlet refrigerants, thus improving the cooling operational efficiency of the cooler, in addition to conserving electric power for the cooler. The apparatus includes a thermal conduction module (32) for cooling the inlet refrigerant for the chamber (1) of the system, a heat exchanger (35) for cooling the outlet refrigerant from the chamber (1), first and second temperature sensors (33) and (36) for sensing the temperatures of the inlet and outlet refrigerants, and a controller (50) controlling the quantity of process cooling water supplied to the module (32) and the heat exchanger (35) using first and second flow control valves (34) and (37) in accordance with the temperatures of the inlet and outlet refrigerants.

Description

APPARATUS FOR CONTROLLING REFRIGERANT TEMPERATURE IN

COOLERS OF SEMICONDUCTOR DEVICE MANUFACTURING SYSTEMS

Technical Field

The present invention relates, in general, to an apparatus for controlling the refrigerant temperature in coolers of semiconductor device manufacturing systems generating gas plasma using radio-frequency waves to accomplish the etching and vapor-deposition processes for the surfaces of target semiconductor wafers and produce desired semiconductor integrated circuit devices and, more particularly, to a refrigerant temperature control apparatus for the coolers of such semiconductor device manufacturing systems, designed to control the supply of process cooling water in accordance with the temperatures of inlet and outlet refrigerants circulating in the cooler of a semiconductor device manufacturing system, thus improving the cooling operational efficiency of the cooler, in addition to conserving electric power.

Background Art

As well known to those skilled in the art, semiconductor integrated circuit devices (hereinbelow, referred to simply as "semiconductor IC devices") are typically produced through etching and vapor-deposition processes for the surfaces of target semiconductor wafers using gas plasma in a vacuum chamber of a semiconductor device manufacturing system.

Fig. 1 is a sectional view, showing the construction of a conventional semiconductor device manufacturing system used for producing such semiconductor IC devices.

As shown in the drawing, the conventional semiconductor device manufacturing system includes a cylindrical vacuum chamber 1, which is made of aluminum and is coated with alumite on its surface. A radio-frequency heating device is provided at the top portion of the chamber 1 such that the heating device is vertically movable in opposite directions. The radio- frequency heating device (hereinbelow, referred to simply as "RF heating device") comprises an electrode moving unit 2 and an upper electrode 4. The electrode moving unit 2 is an air cylinder, and is externally installed on the top wall of the chamber 1. The upper electrode 4 is positioned within the upper portion inside the chamber 1 and is connected to the actuation rod 3 of the electrode moving unit 2.

The upper electrode 4 comprises a flat plate, made of aluminum and coated with alumite on its surface. A reaction gas feed pipe 5 extends from a reaction gas source outside the chamber 1 to the upper electrode 4, and feeds reaction gas, such as argon gas, freon gas, carbon tetrachloride, or carbon trichloride, from the reaction gas source to the upper electrode 4.

The lower surface of the upper electrode 4 is provided with a plurality of perforations, through which the reaction gas is ejected from the upper electrode 4 into the interior of the chamber 1. The upper electrode 4 is also connected to a

RF supply unit 6, installed outside the chamber 1, and so the electrode 4 receives FR waves from the RF supply unit 6 and generates gas plasma using the RF waves within the chamber 1.

A upper cooling block 8, having a circular disc shape, is formed at the top portion of the upper electrode 4, with a refrigerant circulation pipe 7 extending between a refrigerant supply unit (not shown) outside the chamber 1 and the cooling block 8 of the upper electrode 4. Therefore, refrigerant is fed from, the refrigerant supply unit into the cooling block 8 and returns to the refrigerant supply unit while cooling the upper electrode 4. A lower electrode 11 is provided within the lower portion of the chamber 1, and has a lower cooling block 10. This lower cooling block 10 is connected to a refrigerant supply unit (not shown) outside the chamber 1 through both a refrigerant inlet pipe 25 and a refrigerant outlet pipe 9. The lower electrode 11 is thus cooled by the refrigerant in the same manner as that described for the upper electrode 4.

The lower electrode 11 also acts as a semiconductor wafer holder, and so it is necessary to electrically ground the lower electrode 11 so as to prevent an undesired electrostatic fracture of a semiconductor wafer.

The above chamber 1 is designed to be openable by, for example, a gate valve mechanism. In order to feed a semiconductor wafer 12 into the chamber 1 and seat the wafer 12 on the lower electrode 11 within the chamber 1, the semiconductor device manufacturing system is preferably provided with a hand arm. It is also necessary to form a vacuum of several 10 mTorr to several 10 Torr within the chamber 1 using a vacuum pump.

A clamp ring 13, made of aluminum and coated with alumite on its surface, is installed around the top edge of the lower electrode 11, and appropriately compresses the outer edge of the semiconductor wafer 12 to the lower electrode 11. This clamp ring 13 is connected to the actuating rod 14 of an air cylinder-type ring moving unit 15 such that the clamp ring 13 is vertically movable in opposite directions. The above ring moving unit 15 vertically moves the clamp ring 13 in opposite directions so as to hold the semiconductor wafer 12 at a position between the upper and lower electrodes 4 and 11 within the vacuum chamber 1. That is, the ring moving unit 15 forms a wafer clamping mechanism of the system in cooperation with the clamp ring 13. In the above wafer clamping mechanism, the clamp ring 13, made of aluminum and coated with alumite on its surface to become insulating at its surface, is assembled with the actuation rod 14 using set screws. In such a case, the actuation rod 14 has a cylindrical rod shape, and is coated with an insulating etching resin selected from tetrafluorides. In addition, each of the set screws, used for assembling the clamp ring

13 with the actuation rod 14, is coated with an insulating etching resin selected from tetrafluorides. In the same manner, all the conductive metal parts installed in the chamber 1 are entirely coated with such an insulating resin on their surfaces. Three lift pins 18 are vertically, movably arranged in the central portion of the lower electrode 11, and are commonly connected to the air cylinder of a pin moving unit 17 outside the chamber 1 through an actuation rod 16. The three lift pins 18 thus vertically move the semiconductor wafer 12 relative to the lower electrode 11 in opposite directions.

In such a case, a cooling gas passage hole 19 is formed in the lower electrode 11. The three lift pins 18 are vertically, movably set in the lower electrode 11 through a part of the passage hole 19.

The above gas passage hole 19 is connected to a cooling gas supply source outside the chamber 1 through a cooling gas feed pipe 20 such that the gas passage hole 19 feeds cooling gas, such as helium gas, from the gas supply source to the lower surface of the semiconductor wafer 12 seated on the lower electrode 11.

A sheet-shaped synthetic high polymerized film 21 is positioned between the lower surface of the semiconductor wafer 12 and the top surface of the lower electrode 11. This film 21 allows the impedance of the wafer 12 to become equal to that of the lower electrode 11 holding and protecting the wafer

12.

The sheet-shaped synthetic high polymerized film 21 may be preferably made of a thermal resisting polyimide resin, and may preferably have a thickness of20μm ~ lOOμm. An insulating gas exhaust ring 24, made of an ethylene resin and having a plurality of exhaust holes 23, is arranged at the annular gap between the outer edge of the lower electrode 11 and the sidewall of the chamber 1. This gas exhaust ring 24 allows the reaction gas to be exhausted from the chamber 1 to the outside of said chamber 1 through a gas exhaust pipe 22 extending from the sidewall of the chamber 1.

A sealing ring 25, made of an ethylene tetrafluoride insulating resin, covers the outer edge of the upper electrode 4 so as to allow the upper electrode 4 to generate gas plasma within an area almost equal to that of the semiconductor wafer 12 seated on the lower electrode 11. The lower electrode 11 is smoothly convex at its top surface for seating the wafer 12 thereon. This convex surface of the lower electrode 11 has the same radius of curvature as the expected radius of curvature of the wafer 12 when the wafer 12 is uniformly curved by the uniform clamping force applied from the clamp ring 13 clamping the edge of the wafer 12 seated on the lower electrode 11. The semiconductor device manufacturing system is operated as follows during an etching process of etching the surface of a semiconductor wafer 12 to produce a desired semiconductor IC device.

Prior to starting the etching process, the chamber 1 is opened using a gate valve mechanism. A semiconductor wafer 12 is fed into the chamber 1, and is seated on the three lift pins 18, which have been lifted upward on the lower electrode 11 by the pin moving unit 17 having the actuation rod 16. In such a case, the feeding and seating action for the wafer 12 is accomplished by a hand arm.

After the wafer 12 is seated on the lift pins 18, the lift pins 18 are lowered to seat the wafer 12 on the convex top surface of the lower electrode 11.

Thereafter, the clamp ring 13 is appropriately lowered from its lifted position to a compressing position wherein the clamp ring 13 compresses the wafer 12 to the top surface of the lower electrode 11. In such a case, the lowering action of the clamp ring 13 is accomplished by the air cylinder-type ring moving unit 15 having the actuation rod 14.

When the wafer 12 is uniformly compressed at its edge by the clamp ring 13 as described above, the wafer 12 is smoothly curved to accomplish the same radius of curvature as that of the convex top surface of the lower electrode 11 acting as the wafer holder. During such a wafer clamping process, the clamp ring 13 uniformly applies clamping force of about 2kg ~ 3kg to the edge of the wafer 12, thus uniformly compressing the edge of the wafer 12 to the lower electrode 11 while forcibly displacing the edge of the wafer 12 to a position lower than the central portion of the wafer 12 by about 0.7mm ~ 0.8mm. In such a case, the wafer 12 is uniformly compressed to the entire convex top surface of the lower electrode

11 without leaving any noncontact portion between the wafer 12 and the convex top surface of the electrode 11.

After the wafer 12 is completely seated on the lower electrode 11, the reaction gas is injected into the chamber 1. Thereafter, the upper electrode 4 receives RF waves from the RF supply unit 6, and generates gas plasma using the RF waves within the chamber 1. A desired RF heating process is performed to accomplish an etching effect or a vapor-deposition effect on the surface of the wafer 12, thus producing a desired semiconductor IC device.

In the operation of the conventional semiconductor device manufacturing system, it is necessary to precisely maintain the temperature of the wafer 12 in order to improve the quality of the resulting semiconductor IC devices. Therefore, a mechanical compression-cooling unit, using cooled freon gas, has been typically used for maintaining the temperature of the wafer during an operation of the semiconductor device manufacturing system.

However, the mechanical compression-cooling unit, using such cooled freon gas, is problematic in that it has a complex structure and a large volume, and may allow a leakage of gas refrigerant. Another problem experienced in the mechanical compression-cooling unit resides in that the parts of the cooling unit are easily abraded, and so it is necessary to frequently repair the parts of the cooling unit. This undesirably increases the maintenance cost of the semiconductor device manufacturing system.

In an effort to overcome the problems experienced in the mechanical compression-cooling unit, an electronic cooling unit using a thermal conduction module has been proposed and used for maintaining a desired temperature of a semiconductor wafer during an operation of a semiconductor device manufacturing system. Fig. 2 is a block diagram, showing the construction of a conventional electronic refrigerant temperature control apparatus provided with a thermal conduction module. As shown in the drawing, during an operation of a semiconductor device manufacturing system, refrigerant returns from the vacuum chamber 1 of the system to a refrigerant storage tank 30 through a refrigerant return pipe 9. The refrigerant is, thereafter, pumped from the tank

30 by a pump 31, and is fed to the chamber 1 through a refrigerant feed pipe 25. In order to cool the refrigerant flowing through the refrigerant feed pipe 25 before the refrigerant reaches the chamber 1, a thermal conduction module 32, or an electronic cooling unit, is mounted to the refrigerant feed pipe 25. In such a case, the thermal conduction module 32 has a small size, and does not generate operational noise. In addition, the thermal conduction module 32 is designed to selectively heat or cool a target device as desired, and is preferably usable for highly precisely controlling the temperature of a target device by + 0.1 °C.

In order to cool the thermal conduction module 32 during a refrigerant cooling process of the module 32, a sub-cooling means using process cooling water (PCW) is provided at the module 32. In an operation of the sub-cooling means, the process cooling water is fed from a PCW tank (not shown) to the module 32 through a PCW feed pipe 40, and is discharged from the module 32 to the PCW tank through a PCW return pipe 41. A flow control valve 34 is provided on the PCW feed pipe 40 for controlling the amount of process cooling water fed to the module 32 through the feed pipe 40.

However, the above conventional electronic cooling unit having the thermal conduction module 32 is lower in its cooling efficiency in comparison with the mechanical compression-cooling unit, and so it is necessary to excessively consume electric power during an operation of the electric cooling unit having the thermal conduction module 32.

In recent years, the semiconductor device manufacturing systems inevitably generate a large quantity of heat emanating from gas plasma in accordance with the recent trend of enlargement in the size of the semiconductor IC devices. Therefore, it is necessary to install a plurality of thermal conduction modules in the semiconductor device manufacturing system, thus enlarging the size of the system, in addition to forcing the owner of the system to replace the system with a new one or change the parts of the system with new ones.

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a refrigerant temperature control apparatus for the coolers of semiconductor device manufacturing systems generating gas plasma using RF waves to accomplish the etching and vapor-deposition processes for the surfaces of target semiconductor wafers and produce desired semiconductor IC devices, which controls the supply of process cooling water in accordance with the temperatures of inlet and outlet refrigerants circulating in the cooler of a system, thus improving the cooling operational efficiency of the cooler while conserving electric power. In order to accomplish the above object, the present invention provides an apparatus for controlling a refrigerant temperature in a cooler of a semiconductor device manufacturing system, comprising: a refrigerant storage tank storing refrigerant for the vacuum chamber of the system; a pump provided at a refrigerant feed pipe extending from the tank to the chamber and used for pumping the refrigerant of the tank so as to feed the refrigerant from the tank to the chamber; a thermal conduction module mounted to the refrigerant feed pipe at a position between the pump and the chamber and used for cooling inlet refrigerant flowing in the refrigerant feed pipe, with a first sub-cooling means provided at the module for cooling the module using process cooling water supplied thereto through a first PCW feed pipe; a heat exchanger provided at a refrigerant return pipe extending from the chamber to the refrigerant storage tank, and used for cooling outlet refrigerant flowing in the refrigerant return pipe using process cooling water through a heat exchanging process, with a second sub-cooling means provided at the heat exchanger for cooling the heat exchanger using the process cooling water supplied thereto through a second PCW feed pipe; a first temperature sensor provided at the refrigerant feed pipe for sensing a temperature of the inlet refrigerant; a second temperature sensor provided at the refrigerant return pipe for sensing a temperature of the outlet refrigerant; and a controller comparing temperature data output from the first and second temperature sensors with preset reference temperature data, and outputting control signals to first and second flow control valves, respectively provided at the first and second PCW feed pipes, in response to data comparison results, thus controlling the opening ratios of the first and second flow control valves and thereby controlling the quantity of process cooling water supplied to the thermal conduction module and the heat exchanger through the first and second PCW feed pipes.

In the present invention, each of the first and second sub-cooling means for the thermal conduction module and the heat exchanger may use air in place of the process cooling water.

Brief Description of the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a sectional view, showing the construction of a conventional semiconductor device manufacturing system; Fig. 2 is a block diagram, showing the construction of a conventional electronic refrigerant temperature control apparatus for the coolers of semiconductor device manufacturing systems;

Fig. 3 is a block diagram, showing the construction of a refrigerant temperature control apparatus for the coolers of semiconductor device manufacturing systems in accordance with the preferred embodiment of the present invention; and

Fig. 4 is a partially broken perspective view of a heat exchanger included in the refrigerant temperature control apparatus of the present invention.

Best Mode for Carrying Out the Invention

Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. Fig. 3 is a block diagram, showing the construction of a refrigerant temperature control apparatus for the coolers of semiconductor device manufacturing systems in accordance with the preferred embodiment of the present invention. Fig. 4 is a partially broken perspective view of a heat exchanger included in the refrigerant temperature control apparatus of the present invention. As shown in the drawings, a pump 31 is mounted to a refrigerant pipe extending from the refrigerant storage tank 30, and pumps refrigerant from the tank 30 to feed the refrigerant to the vacuum chamber 1 of a semiconductor device manufacturing system. A refrigerant feed pipe 25 extends from the pump 31 to the chamber 1, and feeds the refrigerant to the chamber 1. In order to cool the refrigerant flowing through the refrigerant feed pipe 25 before the refrigerant reaches the chamber 1, a thermal conduction module 32 is mounted to the refrigerant feed pipe 25.

In order to cool the thermal conduction module 32 during a refrigerant cooling process of the module 32, a first sub-cooling means using process cooling water (PCW) is provided at the module 32. In an operation of the sub- cooling means, the process cooling water is fed from a PCW tank (not shown) to the module 32 through a first PCW feed pipe 40, and is discharged from the module 32 to the PCW tank through a first PCW return pipe 41. A first flow control valve 34 is provided on the first PCW feed pipe 40 for controlling the amount of process cooling water fed to the module 32 through the first PCW feed pipe 40.

In order to allow hot refrigerant after cooling the RF heated semiconductor wafer within the chamber 1 to return from the chamber 1 to the refrigerant storage tank 30, a refrigerant return pipe 9 extends from the chamber 1 to the tank 30. A heat exchanger 35 is provided on the refrigerant return pipe 9.

In order to cool the heat exchanger 35, a second sub-cooling means using process cooling water is provided at the heat exchanger 35. In an operation of the second sub-cooling means, the process cooling water is fed from a PCW tank (not shown) to the heat exchanger 35 through a second PCW feed pipe 42, and is discharged from the heat exchanger 35 to the PCW tank through a second PCW return pipe 43. A second flow control valve 37 is provided on the second PCW feed pipe 42 for controlling the amount of process cooling water fed to the heat exchanger 35 through the second PCW feed pipe 42. As best seen in Fig. 4, a plurality of partition walls 35a are regularly, horizontally arranged within the heat exchanger 35 to divide the interior of the heat exchanger 35 into a plurality of refrigerant flow channels and a plurality of PCW flow channels, which are alternately arranged and are completely isolated from each other. Therefore, the hot refrigerant and the process cooling water separately flow in the channels.

A first temperature sensor 33 is mounted on the refrigerant feed pipe 25 extending from the thermal conduction module 32 to the chamber 1, and senses the temperature of inlet refrigerant flowing in the pipe 25. A second temperature sensor 36 is mounted on the refrigerant return pipe 9 extending from the chamber 1 to the heat exchanger 35, and senses the temperature of outlet refrigerant flowing in the pipe 9. The refrigerant temperature control apparatus of this invention also comprises a controller 50, which compares the temperature data output from the first and second temperature sensors 33 and 36 with preset reference temperature data prior to output control signals for controlling the operation of the first and second flow control valves 34 and 37.

The operational effect of the refrigerant temperature control apparatus of this invention will be described herein below.

During an operation of the semiconductor device manufacturing system, hot refrigerant after cooling the RF heated semiconductor wafer within the chamber 1 is discharged from the chamber 1 to the heat exchanger 35 through the refrigerant return pipe 9, and flows in the heat exchanger 35 through the refrigerant flow channels defined by the partition walls 35 a. In such a case, process cooling water is fed from the PCW tank to the heat exchanger 35 through the second PCW feed pipe 42, and flows in the heat exchanger 35 through the PCW flow channels while cooling the hot refrigerant.

In such a case, the second temperature sensor 36 senses the temperature of the refrigerant flowing in the refrigerant return pipe 9, and outputs a temperature signal to the controller 50, which compares the sensed temperature of the refrigerant with a second preset reference temperature. After comparing the sensed temperature of the refrigerant flowing through the refrigerant return pipe 9 with the second preset reference temperature, the controller 50 outputs a control signal to the second flow control valve 37 so as to control the opening ratio of the valve 37. The quantity of process cooling water to be fed to the heat exchanger 35 is thus controlled. Therefore, the temperature of the refrigerant, flowing from the heat exchanger 35 to the refrigerant storage tank 30, is maintained within an allowable range of the second preset reference temperature.

When the controller 50 determines that the sensed temperature of the refrigerant is higher than the second preset reference temperature, the second flow control valve 37 is opened to allow the process cooling water to be fed to the heat exchanger 35. In such a case, the process cooling water quickly flows in the heat exchanger 35 while cooling the refrigerant flowing in the heat exchanger 35. On the other hand, when the controller 50 determines that the sensed temperature of the refrigerant is lower than the second preset reference temperature, the second flow control valve 37 is closed under the control of the controller 50, and so the circulation of the process cooling water for the heat exchanger 35 is stopped, thus preventing the temperature of the refrigerant flowing in the heat exchanger 35 from being further reduced.

When the pump 31 is started to operate, refrigerant is fed from the refrigerant storage tank 30 to the thermal conduction module 32 through the refrigerant feed pipe 25, thus being cooled in the thermal conduction module 32 prior to reaching the chamber 1. Due to the refrigerant cooling operation of the thermal conduction module 32, the temperature of the refrigerant, flowing from the module 32 to the chamber 1, is maintained within an allowable range of a preset reference temperature.

In such a case, the first temperature sensor 33, installed at the refrigerant feed pipe 25, senses the temperature of the refrigerant flowing in the refrigerant feed pipe 25, and outputs a temperature signal to the controller 50, which compares the sensed temperature of the refrigerant for the chamber 1 with a first preset reference temperature. After comparing the sensed temperature of the refrigerant flowing through the refrigerant feed pipe 25 with the first preset reference temperature, the controller 50 outputs a control signal to the first flow control valve 34 so as to control the opening ratio of the valve 34. The quantity of process cooling water to be fed to the thermal conduction module 32 is thus controlled. Therefore, the temperature of the refrigerant, flowing from the module 32 to the chamber 1, is maintained within the desired allowable range of the first preset reference temperature. When the controller 50 determines that the sensed temperature of the refrigerant is higher than the first preset reference temperature, the first flow control valve 34 is opened to allow the process cooling water to be fed to the thermal conduction module 32. In such a case, the process cooling water quickly flows in the module 32 while cooling the refrigerant flowing in the module 32. On the other hand, when the controller 50 determines that the sensed temperature of the refrigerant is lower than the first preset reference temperature, the first flow control valve 34 is closed under the control of the controller 50, and so the circulation of the process cooling water for the thermal conduction module 32 is stopped, thus maintaining the desired temperature of refrigerant for the chamber 1. In such a case, the cooling efficiency of the thermal conduction module 32 is constantly maintained, and so it is possible to precisely maintain the temperature of the refrigerant, flowing from the module 32 to the chamber 1, within the desired allowable range of the first preset reference temperature. In the present invention, it should be understood that the heat exchanger

35 and the thermal conduction module 32 are cooled by refrigerant. However, it should be understood that the heat exchanger 35 and the thermal conduction module 32 are pneumatically operated without affecting the functioning of the present invention. Industrial Applicability

As described above, the present invention provides a refrigerant temperature control apparatus for the coolers of semiconductor device manufacturing systems generating gas plasma using RF waves to accomplish the etching and vapor-deposition processes for the surfaces of target semiconductor wafers, and produce desired semiconductor IC devices. The apparatus of this invention thus precisely controls the supply of process cooling water in accordance with the temperature of refrigerant circulating in the cooler of the semiconductor device manufacturing system, thus improving the cooling operational efficiency of the cooler while conserving electric power for the cooler.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. An apparatus for controlling a refrigerant temperature in a cooler of a semiconductor device manufacturing system, comprising: a refrigerant storage tank storing refrigerant for a chamber of said system; a pump provided at a refrigerant feed pipe extending from the tank to the chamber and used for pumping the refrigerant of said tank so as to feed the refrigerant from the tank to the chamber; a thermal conduction module mounted to said refrigerant feed pipe at a position between the pump and the chamber and used for cooling inlet refrigerant flowing in the refrigerant feed pipe, with first sub-cooling means provided at the module for cooling said module using process cooling water (PCW) supplied thereto through a first PCW feed pipe; a heat exchanger provided at a refrigerant return pipe extending from the chamber to the refrigerant storage tank, and used for cooling outlet refrigerant flowing in the refrigerant return pipe using process cooling water through a heat exchanging process, with second sub-cooling means provided at the heat exchanger for cooling said heat exchanger using the process cooling water supplied thereto through a second PCW feed pipe; a first temperature sensor provided at the refrigerant feed pipe for sensing a temperature of said inlet refrigerant; a second temperature sensor provided at the refrigerant return pipe for sensing a temperature of said outlet refrigerant; and a controller comparing temperature data output from said first and second temperature sensors with preset reference temperature data, and outputting control signals to first and second flow control valves, respectively provided at the first and second PCW feed pipes, in response to data comparison results, thus controlling opening ratios of the first and second flow control valves and thereby controlling the quantity of process cooling water supplied to the thermal conduction module and the heat exchanger through the first and second PCW feed pipes.

2. The apparatus according to claim 1, wherein each of said first and second sub-cooling means for the thermal conduction module and the heat exchanger uses air in place of the process cooling water.