JP5426621B2 - Pulsation reduction device and inspection device - Google Patents

Description

The present invention relates to a pulsation reducing device and an inspection device, and more specifically, for example, a pulsation reducing device that reduces vibrations of a base caused by pulsation when a refrigerant is circulated in the base using a pump, and the pulsation reducing device. It is related with the inspection apparatus provided with.

  As this type of conventional pulsation reducing device, for example, a diaphragm type, a bladder type or a bellows type has been put into practical use. However, any of these methods has a high initial set pressure, and is difficult to operate smoothly in a low pressure region or a negative pressure. In addition, any of these methods has a high spring constant for buffering pulsations and cannot absorb minute pulsations. Furthermore, none of these methods can be used due to the material strength in a low temperature range of −10 ° C., for example. In addition, there is a gas pressure pulsation mitigation device, but the enclosed gas dissolves in the liquid, by gas separation from the liquid such as vaporization of liquid and vaporization of dissolved gas, or by pressure change of the circulating fluid, etc. It is difficult to keep the liquid level in the tank constant.

  Patent Document 1 describes a water level control device for an air chamber that reduces pulsation by a method that is completely different from the above methods. The purpose of this air chamber water level control device is to increase the air replenishment interval of the air chamber in the reciprocating pump and to save labor by reducing the trouble of air replenishment, and to maintain stable operation and stable operation for a long time. Is. In the case of this device, an air chamber such as a suction air chamber filled with air is used as a main chamber, and a water level adjusting pipe capable of causing an internal liquid to flow out by overflow is provided in the main chamber. Connect the auxiliary chamber filled with. Initially, the functions of pulsation damping, cushioning, and capacity compensation work normally without liquid flowing out of the water level adjustment pipe. When air is gradually dissolved and consumed in the liquid and the water level rises, the liquid overflows the water level adjustment pipe and flows out to the auxiliary chamber. The air is pushed out by this amount and replaced into the main chamber. Air capacity is secured.

Japanese Utility Model Publication No. 6-40383

  However, in the case of the pulsation reducing device described in Patent Document 1, the main chamber is arranged at a high position of the auxiliary chamber in the positive pressure pipe on the discharge side of the pump, and the liquid is increased in volume as the air dissolves in the main chamber. The liquid that overflows into the chamber and is reduced by the overflow is replaced with the air in the auxiliary chamber, and pressure increase due to vaporization of the liquid in the main chamber is not assumed. For example, when the object to be processed is cooled on the mounting table like an inspection apparatus for the object to be processed such as a semiconductor wafer and the object to be processed at the time of inspection is maintained at a constant temperature, the refrigerant circulating in the mounting table Is easily vaporized in the main chamber (tank for storing refrigerant), the liquid vaporization capacity exceeds the dissolution capacity of air into the liquid, the pressure of the gas in the tank rises, and the pulsation mitigation function is impaired. . The liquid level in the tank also varies depending on the suction amount and discharge amount of the pump.

The present invention has been made to solve the above problems, lysed with pump is circulated in the base with the liquid level in the tank for storing the refrigerant you cool the base is a gas into the refrigerant Due to the pump , the liquid level in the tank is kept within a certain range even if it changes due to vaporization of the refrigerant , fluctuation of the pump discharge amount, etc., and the gas pressure in the space in the tank is stabilized as a buffer It is an object of the present invention to provide a pulsation reducing device and an inspection device that can reliably and stably reduce pulsation that occurs, and thereby suppress vibrations of a base.

Pulsation reducing device according to claim 1 of the present invention, in the base - a pump to circulate the number 10 ° C. refrigerant reaching the low temperature range for cooling the base, the refrigerant circulating through the pump A pulsation reducing device that uses a gas in a space on a liquid surface in the tank as a buffer to reduce pulsation of the refrigerant by the pump. The tank is provided on the refrigerant discharge side by the pump, and the refrigerant liquid increases by the dissolution of the gas from the space in the tank to the refrigerant under a positive pressure by the refrigerant discharge from the pump. A first liquid level sensor that detects and monitors the upper limit of the surface and the upper limit of the liquid level of the refrigerant due to an increase in the discharge amount of the pump, and the liquid level of the refrigerant in the tank due to a decrease in the discharge amount of the pump. lower limit A second liquid level sensor for detecting and monitoring is provided in each of the tanks, and a branch pipe branched from a pipe connected to the gas supply source is connected to the tank, and the branch pipe is sandwiched between the pipes. First and second valves are provided at positions, and a control device for opening and closing the first and second valves based on detection signals of the first and second liquid level sensors is provided. The control device includes the first and second valves. Based on the detection signal of the liquid level sensor, the first valve is opened, the gas is supplied from the gas supply source to the tank via the branch pipe, and the gas in the tank is pressurized to increase the pressure in the tank. The coolant level is lowered from the upper limit, and the second valve is opened based on the detection signal of the second liquid level sensor, and the gas in the tank is passed from the second valve via the branch pipe. Discharge to the outside By depressurizing the gas in the tank and raising the liquid level of the refrigerant in the tank from the lower limit, the height of the liquid level of the refrigerant in the tank is controlled within a predetermined range, and the buffering of the gas is performed. The body pressure is maintained in a predetermined range.

The inspection apparatus according to claim 2 of the present invention, a base that mounts the object, in this base - cooled by circulating said base number 10 ° C. refrigerant reaching the low-temperature region of the And a tank for storing the refrigerant that circulates through the pump. In an inspection apparatus that inspects an object to be processed on the base, first and second tanks provided as the tank the gas in the space on each of the liquid surface of the inner, first, negative pressure side and the positive pressure side of the second pulsation reducing device the pump for use as a buffer to reduce each pulsation of the refrigerant by the pump provided in each, as the second pulsation reducing device provided explicitly pressure side of the pump, positive pressure by the discharge of the refrigerant from the second tank provided Rutotomoni, the pump to the discharge side of the coolant by said pump in the second tank A first liquid level sensor for detecting and monitoring an upper limit of the liquid level of the refrigerant, which is increased by dissolution of the gas from the space portion to the refrigerant, and an upper limit of the liquid level of the refrigerant due to an increase in the discharge amount of the pump; detecting the lower limit of the liquid level of the refrigerant by reducing the discharge amount of the pump, respectively the second liquid level sensor to monitor to the second tank, also above the second tank is connected to a source of the gas Branch pipes branching from the pipes are connected, and the pipes are provided with first and second valves at positions sandwiching the branch pipes, and the first and second liquid level sensors are used to detect the first and second liquid level sensors. A control device for controlling opening and closing of the second valve is provided, and the control device opens the first valve based on a detection signal of the first liquid level sensor and supplies the second valve from the gas supply source through the branch pipe . Supply the above gas into the tank Te pressurizes the gas in the second tank lowers the liquid level of the refrigerant in the second tank from the upper limit, also open the second valve based on a detection signal of said second level sensor the liquid level of the refrigerant in the gas and by vacuum the second tank in the second tank by discharging the gas to the outside in the second tank from said second valve via the branch pipe By raising from the lower limit, the height of the coolant level in the second tank is controlled within a predetermined range, and the pressure as the gas buffer is maintained within the predetermined range. It is characterized by this.

According to the present invention, by using a pump to circulate the base by dissolution or vaporization of the refrigerant in the gas liquid level in the tank for storing the refrigerant you cool the base is to the refrigerant, or the discharge amount of the pump The liquid level in the tank is maintained in a certain range even if it changes due to fluctuations in the tank, etc., and the pressure of the gas in the space in the tank is stabilized as a buffer to constantly and stably reduce pulsation caused by the pump Thus, it is possible to provide a pulsation reducing device and an inspection device that can suppress vibrations of the base.

  Hereinafter, the present invention will be described based on the embodiment shown in FIGS. 1 is a block diagram conceptually showing an inspection apparatus to which the pulsation reducing apparatus of the present invention is applied, FIG. 2 is a block diagram showing the first pulsation reducing apparatus of the inspection apparatus shown in FIG. 1, and FIG. It is a block diagram which shows the 2nd pulsation reduction apparatus of the test | inspection apparatus shown. In each figure, an arrow indicated by a solid line indicates a refrigerant flow, and an arrow indicated by a broken line indicates a gas flow.

  As shown in FIG. 1, for example, the inspection apparatus 10 of the present embodiment is connected to a mounting table 11 on which an object to be processed (for example, a semiconductor wafer) W is mounted, and the mounting table 11 and a circulation pipe 12. A pump 13 for supplying and circulating a refrigerant into the mounting table 11, and a heat exchanger 14 for cooling the heated refrigerant circulating through the circulation pipe 12 from the mounting table 11 to the original temperature via the pump 13. The semiconductor wafer W on the mounting table 11 is cooled with a coolant and the electrical characteristics of the semiconductor wafer W are inspected at a predetermined temperature. The mounting table 11 moves in the horizontal direction and the vertical direction in order to bring the semiconductor wafer W and a probe card (not shown) into contact with each other during inspection.

  The mounting table 11 is cooled by a refrigerant so that the electrical property inspection of the semiconductor wafer W can be performed at an appropriate temperature within a range of −10 ° C. to 150 ° C., for example. As the refrigerant used at this time, for example, a fluorine-based inert liquid (Fluorinert (trade name) manufactured by Sumitomo 3M, Galden (trade name) manufactured by Solvay Solexis, etc.) can be used.

  When the refrigerant is circulated by the pump 13, the mounting table 11 and the circulation pipe 12 are slightly vibrated by the pulsation of the refrigerant. The vibration of the mounting table 11 affects the contact pressure between the semiconductor wafer W and the probe card, and may adversely affect the inspection of the semiconductor wafer W. The influence of pulsation appears more prominently as the integrated circuit formed on the semiconductor wafer W becomes denser and the wiring layer and insulating layer become thinner. Therefore, in the present embodiment, first and second pulsation reducing devices 15 and 16 are provided in the circulation pipe 12 in order to reduce pulsation caused by the pump 13. The first pulsation reducing device 15 is arranged on the negative pressure side for sucking the refrigerant by the pump 13, and the second pulsation reducing device 16 is arranged on the positive pressure side for discharging the refrigerant from the pump 13.

  For example, as shown in FIG. 2, the first pulsation reducing device 15 is provided in the circulation pipe 12, and the first tank 15 </ b> A that stores the refrigerant leaving a space and the circulation pipe 12 in the same manner as the first tank 15 </ b> A. And a replenishing tank 15B for storing refrigerant for replenishing the first tank 15A while leaving a space, and a gas such as air in the space of the first tank 15A serves as a buffer to reduce pulsation. It is configured as follows.

  The replenishing tank 15B is disposed at a position where the liquid level is higher than that of the first tank 15A. As will be described later, the refrigerant in the first tank 15A evaporates and the pressure in the space portion increases and the liquid amount decreases. When the liquid level falls, the refrigerant is replenished into the first tank 15A, and the liquid level of the refrigerant in the first tank 15A is kept constant.

  That is, the first tank 15A and the replenishment tank 15B are connected via the gas vent pipe 15C. The connection part of the gas vent pipe 15C with the first tank 15A is usually located in the refrigerant slightly below the space part, and the connection part of the gas vent pipe 15C with the replenishing tank 15B is always located in the space part. Yes. For this reason, the space part of the first tank 15A and the space part of the replenishing tank 15B are normally blocked. However, when the refrigerant in the first tank 15A is vaporized, the amount of liquid is reduced, the pressure in the space is increased, the liquid level of the refrigerant is lowered, and the liquid level reaches the connection with the venting pipe 15C. The space portion of the first tank 15A communicates with the space portion of the replenishment tank 15B, the gas in the first tank 15A moves to the space portion of the replenishment tank 15B, and the pressure in the space portion of the replenishment tank 15B increases.

A relief valve 15D is attached to the space portion of the replenishing tank 15B. When the relief valve 15D exceeds a predetermined pressure (for example, 0.1 kg / cm ² G), the space portion is automatically opened to the atmosphere, and the replenishing tank The gas in 15B (including the vaporized refrigerant) is released to the atmosphere side. When the pressure in the space in the replenishing tank 15B decreases due to the release of gas, the relief valve 15D is automatically closed. At this time, since the replenishment tank 15B is arranged at a position higher than the first tank 15A, the refrigerant in the replenishment tank 15B is first due to the hydraulic pressure difference between the refrigerant in the first tank 15A and the refrigerant in the replenishment tank 15B. The tank 15A is replenished, the liquid level in the first tank 15A is returned to its original state, the connection part with the gas vent pipe 15C is sealed, and the space part of the first tank 15A and the replenishment tank 15B is shut off.

  Further, as shown in FIG. 3, for example, the second pulsation reducing device 16 is connected to the circulation pipe 12 to store the refrigerant while leaving a space, and the liquid level of the refrigerant in the second tank 16A. Air that is electrically connected to the first and second liquid level sensors 16B and 16C, and detects the signals from the sensors 16B and 16C. And a control device 16D configured to act as a buffer that reduces pulsation when a gas such as air filling the space of the second tank 16A discharges the refrigerant from the pump 13.

  An air pipe 16E is connected to the second tank 16A, and dry air in the factory is introduced into the second tank 16A through the air pipe 16E and the gas in the second tank 16A is discharged to the outside as will be described later. . That is, a pressure regulating valve 16F, first and second valves 16G, 16H are sequentially arranged in the air pipe 16E from the upstream side to the downstream side, and the dry air is adjusted to a predetermined pressure by the pressure regulating valve 16F. 1. The dry air is introduced into the second tank 16A through the second valves 16G and 16H and discharged. A branch pipe that connects the air pipe 16E and the second tank 16A is provided between the first and second valves 16G and 16H. This branch pipe is provided with a throttle 16I, which restricts the flow rate of air flowing through the branch pipe. The first and second valves 16G and 16H are both electrically connected to the air control device 16D and open and close under the control of the air control device 16D.

  When the liquid level in the second tank 16A rises and reaches the upper limit, and the first liquid level sensor 16B detects the liquid level, the first liquid level sensor 16B transmits a detection signal to the air control device 16D. The air control device 16D opens the first valve 16G based on the detection signal of the first liquid level sensor 16B, introduces and pressurizes dry air into the second tank 16A through the air pipe 16E and its branch pipe, Lower the coolant level. The second liquid level sensor 16C transmits a detection signal to the air control device 16D when the liquid level in the second tank 16A falls to reach the lower limit and detects the liquid level. The air control device 16D opens the second valve 16H based on the detection signal of the second liquid level sensor 16C, discharges the gas in the second tank 16A through the branch pipe and the air pipe 16E, and reduces the pressure of the refrigerant. Raise the liquid level.

  Accordingly, the air control device 16D opens and closes the first and second valves 16G and 16H based on the detection signals of the first and second liquid level sensors 16B and 16C, and the gas pressure in the space in the second tank 16A. Is maintained constant, the liquid level of the refrigerant is maintained constant. Note that 16J is a communication pipe that communicates the refrigerant section and the space section in the second tank 16A, and the first and second liquid level sensors 16B and 16C are attached to the communication pipe 16J.

  Next, the operation will be described. When the semiconductor wafer W is inspected, the pump 13 is driven to circulate a coolant at a constant flow rate in the mounting table 11 to cool the mounting table 11. By cooling the mounting table 11, the semiconductor wafer W on the mounting table 11 is cooled even if heat is generated during inspection, and is maintained at a predetermined temperature. When the refrigerant is sucked and discharged by the pump 13, the refrigerant pulsates. In the present embodiment, the first and second pulsation reducing devices 15 and 16 work to reduce the pulsation, and thus the mounting table 11 and the circulation pipe 12. Vibration can be suppressed and prevented, and the reliability of inspection can be improved.

  That is, when the pump 13 is driven and sucks the refrigerant, when the refrigerant passes through the first tank 15A of the first pulsation reducing device 15, a gas such as air in the space in the first tank 15A becomes a buffer. The pulsation on the suction side of the pump 13 is reduced. Further, when the refrigerant is discharged from the pump 13, the refrigerant passes through the heat exchanger 14 via the circulation pipe 12, where the refrigerant is cooled and then passes through the second tank 16 </ b> A of the second pulsation reducing device 16. When the refrigerant passes through the second tank 16A, a gas such as air in the space in the second tank 16A serves as a buffer to reduce pulsation on the discharge side of the pump 13.

  Thus, even when the refrigerant pulsates due to the suction and discharge operations of the refrigerant by the pump 13, the first pulsation reducing device 15 reduces the pulsation on the suction side, and the second pulsation reducing device 16 reduces the pulsation on the discharge side. In addition, vibration due to pulsation of the mounting table 11 and the circulation pipe 12 can be remarkably suppressed or prevented, and the reliability of the inspection of the semiconductor wafer W can be improved.

  By the way, when the inspection is continued, the first pulsation reducing device 15 vaporizes the refrigerant in the first tank 15A due to the negative pressure of the pump suction pressure, and the refrigerant gradually decreases and the pressure in the space portion rises. The surface is lowered. When the liquid level of the refrigerant decreases in the first tank 15A and reaches the connection portion with the gas vent pipe 15C, the space portion of the first tank 15A and the space portion of the replenishing tank 15B communicate with each other. Since the space in the first tank 15A is higher in pressure than the space in the replenishing tank 15B, the gas in the first tank 15A moves to the space in the replenishing tank 15B, and the pressure in the space in the replenishing tank 15B increases. To do.

  In the replenishing tank 15B, the relief valve 15D is actuated to open the space to the atmosphere side, releasing the gas in the space and refilling the first tank 15A with the refrigerant. The pressure in the space in the replenishing tank 15B decreases due to the release of the gas, and the relief valve 15D is closed. Along with this, the refrigerant is replenished from the replenishment tank 15B into the first tank 15A due to the difference in liquid level between the refrigerant in the replenishment tank 15B and the refrigerant in the first tank 15A. In the first tank 15A, the liquid level rises, returns to the initial liquid level height, and at the same time seals the connection with the gas vent pipe 15C to shut off from the replenishing tank 15B, and continues normal pulsation reducing action. To do.

  In the second pulsation reducing device 16, the gas is dissolved in the refrigerant by the action of the positive pressure of the pump discharge pressure in the second tank 16 </ b> A, contrary to the first pulsation reducing device 15. When the liquid level of the refrigerant rises due to gas dissolution in the second tank 16A and the first liquid level sensor 16B detects the liquid level, the air control device 16D detects the detection based on the detection signal from the first liquid level sensor 16B. The first valve 16G is opened, and dry air is introduced into the second tank 16A from the air pipe 16E to lower the liquid level. When the liquid level returns and the detection signal from the first liquid level sensor 16B disappears, the air control device 16D closes the first valve 16G and stops the introduction of dry air.

  Further, when the discharge amount of the pump 13 varies, the liquid level of the refrigerant in the second tank 16A also varies. When the discharge amount increases and the liquid level of the refrigerant rises in the second tank 16A and the first liquid level sensor 16B detects the liquid level, the air control device 16D generates a detection signal from the first liquid level sensor 16B. Based on this, the first valve 16G is opened, and dry air is introduced into the second tank 16A from the air pipe 16E to lower the liquid level. When the liquid level returns and the detection signal from the first liquid level sensor 16B disappears, the air control device 16D closes the first valve 16G and stops the introduction of dry air. Conversely, when the discharge amount decreases and the liquid level decreases, the second liquid level sensor 16C operates, opens the second valve 16H via the air control device 16D, exhausts the gas in the second tank 16A, and then the liquid level. Raise the face.

  As described above, according to the present embodiment, the second pulsation reducing device 16 is provided on the refrigerant discharge side of the pump 13, and the second pulsation reducing device 16 includes the second tank 16 </ b> A that stores the refrigerant while leaving a space. A first liquid level sensor 16B that detects the upper limit of the liquid level of the refrigerant in the second tank 16A, and a second liquid level sensor 16C that detects the lower limit of the liquid level of the refrigerant in the second tank 16A. Since the height of the liquid level in the second tank 16A is controlled within a predetermined range based on the detection signals of the second liquid level sensors 16B and 16C, the space on the liquid level in the second tank 16A. When the pulsation of the refrigerant by the pump 13 is reduced by using the gas in the gas as a buffer, the gas is dissolved in the refrigerant by the action of the positive pressure of the pump discharge pressure in the second tank 16A, or the discharge amount is increased. Even if the liquid level rises, the first and second liquids Based on the detection signals of the sensors 16B and 16C, the liquid level height of the refrigerant in the second tank 16A can be kept constant and the gas pressure in the space can be kept constant, so that the pulsation can always be reliably and stably reduced. .

  Further, a first valve 16G for introducing dry air into the second tank 16A based on the detection signal of the first liquid level sensor 16B is provided, and the inside of the second tank 16A based on the detection signal of the second liquid level sensor 16C. A second valve 16H for exhausting the gas is provided, and an air control device 16D for opening and closing the first and second valves 16G and 16H based on detection signals of the first and second liquid level sensors 16B and 16C is provided. For this reason, the gas pressure in the space in the second tank 16A can be more reliably maintained constant.

  Further, according to the present embodiment, since the first and second pulsation reducing devices 15 and 16 are provided on the suction side and the discharge side of the pump 13 of the refrigerant circulation pipe 12 of the inspection apparatus 10, the mounting table 11 and the circulation pipe are provided. Thus, the reliability of the inspection of the semiconductor wafer W can be improved by reliably suppressing or preventing the vibration of the semiconductor wafer 12.

  Further, according to the present embodiment, the first pulsation reducing device 15 is provided on the refrigerant suction side of the pump 13, and the first pulsation reducing device 15 includes the first tank 15 </ b> A that stores the refrigerant leaving the space portion, and the first tank 15 </ b> A. A replenishing tank 15B connected to the tank 15A at a higher position and replenishing the refrigerant into the first tank 15A, and a gas vent pipe 15C connecting the first tank 15A and the space of the replenishing tank 15B. When the pulsation of the refrigerant by the pump 13 is reduced by using the gas in the space in the first tank 15A as a buffer, the refrigerant in the first tank 15A is vaporized and reduced, and the space When the pressure in the tank rises and the liquid level decreases, the space in the first tank 15A and the space in the replenishing tank 15B communicate with each other via the gas vent pipe 15C. 1 Since the gas in A is extracted to the space in the replenishing tank 15B and the refrigerant in the replenishing tank 15B is replenished to the first tank 15A based on the hydraulic pressure difference, the gas in the first tank 15A is degassed. The constant pressure is always maintained in cooperation with the replenishing tank 15B via 15C, and the pulsation can always be reliably and stably reduced.

  In addition, when the space portion in the first tank 15A and the space portion in the replenishing tank 15B communicate with each other, the relief valve 15D that opens the space portion to the atmosphere by the gas pressure in the replenishing tank 15B is provided. The refrigerant in 15B can be replenished to the first tank 15A to keep the gas pressure in the space in the first tank 15A constant, and a more stable pulsation reducing action can be maintained.

  In the above embodiment, the case where the first and second pulsation reducing devices 15 and 16 are provided in the inspection apparatus 10 has been described. However, the present invention is not limited to the above embodiment, and the semiconductor wafer W or the like is not limited. The present invention can be widely applied to a semiconductor manufacturing apparatus having a mounting table for controlling the temperature of an object to be processed and a liquid circulation circuit in which a liquid such as a heat medium circulates in the base.

  The present invention can be suitably used for a semiconductor manufacturing apparatus, for example, an inspection apparatus.

It is a block diagram which shows notionally the inspection apparatus to which the pulsation reduction apparatus of this invention is applied. It is a block diagram which shows the 1st pulsation reduction apparatus of the test | inspection apparatus shown in FIG. It is a block diagram which shows the 2nd pulsation reduction apparatus of the test | inspection apparatus shown in FIG.

10 Inspection equipment 11 Mounting table (base)
13 Pump 15 First pulsation reducing device 15A First tank 15B Replenishment tank 15C Gas vent pipe 15D Relief valve 16 Second pulsation reducing device 16A Second tank 16B First liquid level sensor 16C Second liquid level sensor 16D Air control unit 16G First 1 valve 16H 2nd valve

Claims (2)

In base - and a pump for circulating the number 10 ° C. refrigerant reaching the low temperature range for cooling the base with a tank for storing the refrigerant circulating through the pump, used in apparatus equipped with, A pulsation reducing device that uses the gas in the space above the liquid level in the tank as a buffer, and reduces the pulsation of the refrigerant by the pump,
The tank is provided on the refrigerant discharge side of the pump,
Under the positive pressure due to the discharge of the refrigerant from the pump, the upper limit of the liquid level of the refrigerant that increases due to the dissolution of the gas from the space in the tank to the refrigerant, and the increase in the discharge amount of the pump A first liquid level sensor for detecting and monitoring the upper limit of the liquid level and a second liquid level sensor for detecting and monitoring the lower limit of the liquid level of the refrigerant in the tank due to a decrease in the discharge amount of the pump are provided in the tank. Each provided,
The tank is connected to a branch pipe branched from a pipe connected to the gas supply source. The pipe is provided with first and second valves at positions sandwiching the branch pipe, and the first and second A control device for controlling opening and closing of the first and second valves based on the detection signal of the two liquid level sensor is provided,
The control device opens the first valve based on a detection signal of the first liquid level sensor, supplies the gas into the tank from the gas supply source via the branch pipe, and supplies the gas in the tank. Gas is pressurized to lower the liquid level of the refrigerant in the tank from the upper limit, and the second valve is opened based on the detection signal of the second liquid level sensor, and the second valve is passed through the branch pipe. The gas in the tank is discharged to the outside, the gas in the tank is depressurized, and the liquid level of the refrigerant in the tank is raised from the lower limit, whereby the liquid level of the refrigerant in the tank is increased. A pulsation reducing device characterized by controlling the height within a predetermined range and maintaining the pressure as the gas buffer in a predetermined range. Storing a pump to circulate the number 10 ° C. refrigerant reaching the low temperature range for cooling the base, the said refrigerant circulating through the pump - a base that mounts the object, in this base An inspection apparatus for inspecting an object to be processed on the base,
First, the gas in the space on each of the liquid surface of the second tank, the first, second pulsation reducing utilized as a buffer to reduce each pulsation of the refrigerant by the pump provided as the tank the device provided on each negative pressure side and the positive pressure side of the pump,
As the second pulsation reducing device provided explicitly pressure side of the pump,
Rutotomoni provided with the second tank to the discharge side of the coolant by said pump,
The upper limit of the liquid level of the refrigerant that increases due to the dissolution of the gas from the space in the second tank to the refrigerant under positive pressure due to the discharge of the refrigerant from the pump, and the increase in the discharge amount of the pump. A first liquid level sensor for detecting and monitoring the upper limit of the liquid level of the refrigerant and a second liquid level sensor for detecting and monitoring the lower limit of the liquid level of the refrigerant due to a decrease in the discharge amount of the pump are provided in the second tank, respectively. Provided,
The second tank is connected to a branch pipe branched from a pipe connected to the gas supply source. The pipe is provided with first and second valves at positions sandwiching the branch pipe and the first tank. A control device for controlling the opening and closing of the first and second valves based on a detection signal of the second liquid level sensor;
The control device, the second by supplying the gas to the second tank through the branch pipe from a source of the gas opening the first valve based on a detection signal of the first level sensor The gas in the tank is pressurized to lower the liquid level of the refrigerant in the second tank from the upper limit, and the second valve is opened based on the detection signal of the second liquid level sensor to open the branch pipe. Via the second valve, the gas in the second tank is discharged to the outside, the gas in the second tank is decompressed, and the liquid level of the refrigerant in the second tank is raised from the lower limit. Thus, the liquid level of the refrigerant in the second tank is controlled within a predetermined range, and the pressure as the gas buffer is maintained within a predetermined range. Inspection device to do.

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