JP3310566B2 - Pumps for semiconductor manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump for a semiconductor manufacturing apparatus applied to circulating transport of chemicals used for various processes such as surface cleaning of ICs and liquid crystals in the semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art As a pump of this type, a bellows type or diaphragm type reciprocating pump having a structure as disclosed in, for example, JP-A-3-179184 has been generally used. The configuration of this conventional reciprocating pump will be briefly described with reference to FIG. FIG. 3 shows an air-driven bellows type pump,
A cylindrical casing 53 fixedly connected to both sides of a pump head constituting wall 52 having a liquid inflow path 50 and a liquid inflow path 51.
A and 53B, a pair of bellows 54A and 54B that can be expanded and contracted in the same direction are disposed in opposition to each other, and the opening peripheral portions 54a and 54a of the pair of bellows 54A and 54B are arranged.
The pump chamber 59 is hermetically sealed into pump working chambers 57a and 57b and pump working chambers 58a and 58b by fixing the pump chamber 54b to the pump head constituting wall 52 in an airtight manner via annular fixing plates 56A and 56B. A pair of pump parts 6
0A and 60B are configured.

The bellows 54A, 54B of the pair of pump parts 60A, 60B are connected to the pump head forming wall 5
The bellows 54A or 54B is interlocked and connected via a plurality of connecting rods 55 extending in the circumferential direction provided through the second bellows 2 so that when one bellows 54A or 54B contracts, the other bellows 54B or 54A extends. . In addition, the pump action chamber 57 of the pair of pump sections 60A and 60B.
The suction ports 61a, 61b and the discharge ports 62a, 62b formed to open to the a, 57b respectively communicate with the inflow path 50 and the outflow path 51, respectively. 62a,
The check valves 62b are provided with suction check valves 63a and 63b and discharge check valves 64a and 64b, respectively. Further, the bottom plate portion 53 of the cylindrical casings 53A and 53B.
Air ports 65a, 65b for alternately supplying pressurized air to the pump working chambers 58a, 58b of the pair of pump sections 60A, 60B at predetermined time intervals are formed in a and 53b.

In the bellows type pump reciprocating pump having the above structure, pressurized air supplied from a pressurized air supply device (not shown) such as a compressor is alternately provided at predetermined time intervals through a pair of air ports 65a and 65b. Supply to the pump working chambers 58a, 58b of the pump sections 60A, 60B, the bellows 54A, 54B are reversibly driven to expand and contract via the connecting rod 55, and the suction process of the pair of pump sections 60A, 60B is performed. The discharge step and the discharge step are alternately performed, whereby a pump action is performed such that the liquid flowing into the pump action chambers 57a and 57b from the inflow path 50 is almost continuously discharged to the outflow path 51.

[0005]

However, in the conventional reciprocating pump as described above, a pair of bellows or diaphragms or other pump working elements are alternately operated, so that the liquid is discharged when the operation is switched. A pulsation occurs because of an instantaneous stop. When such a pulsation occurs, a large change in the flow velocity and a change in the pressure are caused, and in the circulating transport of the processing liquid in the semiconductor manufacturing apparatus, the cleanliness thereof is impaired, and a serious problem in a predetermined processing accuracy is caused. Had become.

In order to prevent the processing accuracy from deteriorating due to such pulsation, a means for arranging a pulsation suppressing device such as an accumulator using a bellows, for example, in a pipe downstream of the liquid transport pipe by a pump is adopted. However, in this case, since a pump and a pulsation suppressing device such as an accumulator are provided side by side, a large space is required, and complicated piping is also required between the two. Equipment costs increase. In particular, when circulating and transporting a processing solution for a semiconductor manufacturing apparatus, a tube made of a fluororesin such as PTFE or PFA having excellent corrosion resistance and heat resistance is often used as a pipe between the two. If a small pulsation or a large pulsation repeatedly acts on the tube, there is a danger that the tube is fatigued and breaks in a short period of time, causing liquid leakage, which is not preferable in terms of safety. In addition, pressure loss occurs at the connection point between the fluorine resin tube and the tube and the pump or the pulsation suppression device,
Since it is necessary to use a pump having a large capacity in anticipation of the pressure loss, there is a problem that the equipment including the two is larger and the occupied installation space is further increased.

The present invention has been made in view of the above circumstances, and can suppress the generation of pulsation, continuously and smoothly circulate and transport a liquid. It is a main object of the present invention to provide a pump for a semiconductor manufacturing apparatus capable of greatly reducing an installation space due to the development.

Another object of the present invention is to provide, in addition to the above objects,
The point is that the pulsation width can be kept small irrespective of the fluctuation of the discharge pressure.

[0009]

According to a first aspect of the present invention, there is provided a pump for a semiconductor manufacturing apparatus, comprising: a partition wall having an inflow path and an outflow path for a liquid; A bellows that expands and contracts and moves in a casing fixedly connected to one side of the partition wall, an air cylinder unit that drives and expands and contracts this bellows, and an opening and closing operation that alternately opens and closes with the expansion and contraction movement of the bellows to transfer liquid. A reciprocating pump section including a pump action chamber provided with a check valve comprising a movable valve body performing a suction action and a discharge action and a spring; and a casing fixedly connected to the other side of the partition wall. And a bellows disposed opposite to the bellows of the reciprocating pump unit and capable of expanding and contracting in the direction of the expanding and contracting movement of the bellows. A liquid chamber capable of temporarily storing the liquid discharged from the working chamber via the discharge check valve, and a gas chamber which is formed separately from the liquid chamber on the other side of the bellows and in which a pulsation suppressing gas is sealed. A pulsation suppressor configured to absorb pulsation due to the discharge pressure of liquid discharged from the pump action chamber of the reciprocating pump unit due to a change in the capacity of the liquid chamber due to the expansion and contraction movement of the bellows. It is characterized by having.

According to the first aspect of the present invention, when the bellows in the reciprocating pump section on one side of the partition wall is driven to reciprocate via the air cylinder section, the suction check valve and the discharge in the pump working chamber are discharged. The check valve alternately opens and closes, and the suction of the liquid from the inflow path of the liquid to the pumping chamber and the discharge of the liquid from the pumping chamber to the outflow path are repeated, and a predetermined pump action is performed. At this time, the liquid discharged from the pump action chamber in the reciprocating pump section via the discharge check valve flows out to the outflow path through the liquid chamber in the pulsation suppression section on the other side of the partition wall. In the ridge of the pulsation of the discharge pressure of the discharge liquid, the bellows in the pulsation suppressor moves in the direction of increasing the liquid chamber capacity to absorb the pressure, and in the valley of pulsation, the bellows reduces the liquid chamber capacity. By moving in the decreasing direction, the pressure of the discharged liquid rises and the pulsation is absorbed, so that the liquid can be continuously and smoothly discharged without pulsation.

In the pump for a semiconductor manufacturing apparatus that operates as described above, the reciprocating pump section and the pulsation suppressing section are integrated, and no external piping is required for connecting the two. Not only can the cost and size be reduced, but the installation space can be significantly reduced, and the omission of external piping eliminates the danger that the piping will break even after long-term use and cause liquid leakage. Also, since the pressure loss is very small, the pump capacity may be small, the size can be further reduced, and the area occupied by the pump can be reduced.

In the pump for a semiconductor manufacturing apparatus having the above structure, the partition wall, the casing in the reciprocating pump section and the pulsation suppressing section, the movable valve body of the suction and discharge check valves in the reciprocating pump section, and the reciprocating pump. As a constituent material of the bellows in the section and the bellows in the pulsation suppressing section, considering the use conditions in which corrosion resistance and heat resistance such as circulating transport of a processing liquid for semiconductor manufacturing equipment are required, as described in claim 2, It is desirable to use a fluorine resin material such as PTFE, PFA or the like.

According to a third aspect of the present invention, in the pump for a semiconductor manufacturing apparatus according to the first or second aspect, the bellows is inserted into the air chamber in the pulsation suppressing portion and responds to the expansion and contraction movement of the bellows. A possible operating rod and a supply / exhaust passage which is operated by the operating rod and communicates with the air chamber to an air supply port when the capacity of the liquid chamber increases beyond a predetermined range, and the capacity of the liquid chamber is within a predetermined range. And a switching valve mechanism for air supply / exhaust provided with a valve element selectively communicating with the exhaust port when the pressure is reduced beyond the range. According to the pump operation with pulsation suppression as described above, if the increase in the volume of the liquid chamber exceeds a predetermined range due to the fluctuation of the discharge pressure of the reciprocating pump, the air supply / exhaust valve mechanism causes the air supply into the air chamber. The filling pressure is increased and the bellows There are limitations, and when the reduction of the liquid chamber volume exceeds the predetermined range, the filling pressure is carried out exhaust from the gas chamber is lowered by the intake and exhaust valve mechanism, movement of the bellows is limited. As a result, the movement of the bellows is restricted within a certain range irrespective of the fluctuation of the discharge pressure from the reciprocating pump unit, and the pulsation width can be reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall vertical sectional front view of an air-driven bellows type pump applied as an embodiment of a pump for a semiconductor manufacturing apparatus according to the present invention. In FIG. The reciprocating pump unit 4 and the pulsation suppression unit 5 are integrally disposed on both sides of the partition wall 1 so as to face each other.

A bottomed tubular bellows 7 is provided in a bottomed tubular casing 6 fixedly connected to one side of the partition wall 1 so as to be able to expand and contract along the cylinder axis direction. The peripheral edge 7a of the opening of the bellows 7 is pressed and fixed to one side surface of the partition wall 1 by an annular fixing plate 8 in an airtight manner.
The internal space of the casing 6 is hermetically partitioned into a pump working chamber 9a inside the bellows 7 and a pump working chamber 9b outside the bellows 7. A cylinder body 12 that slidably houses a piston body 11 fixedly connected to the closed end member 7b of the bellows 7 via a connecting member 10 is fixed to the outside of the bottom wall 6a of the bottomed cylindrical casing 6. The pressurized air supplied from a pressurized air supply device (not shown) such as a compressor is passed through the cylinder body 12 and air holes 13a and 13b formed in the bottom wall 6a of the casing 6. An air cylinder section 14 for driving and expanding and contracting the bellows 7 by supplying the inside of the bellows 11 or the pump working chamber 9b is formed.

Further, a suction port 15a and a discharge port 15b formed to open to the pump action chamber 9a, respectively.
Are connected to the inflow passage 2 and the outflow passage 3 and each of the suction port 15a and the discharge port 15b includes a movable valve body 16a1 and a spring 16a2, and a movable valve body 16b1 and a spring 16b2. A check valve 16a for suction and a check valve 16b for discharge, which are alternately opened and closed in accordance with the drive expansion and contraction, are provided, and the above-mentioned components constitute the pump section 4.

On the other hand, a bottomed cylindrical bellows 7 of the pump section 4 is also provided in a bottomed cylindrical casing 17 fixedly and coaxially provided with the bottomed cylindrical casing 6 on the other side of the partition wall 1. A bellows 18 having a bottomed cylindrical shape, which can be expanded and contracted along the cylinder axis direction, is disposed so as to face the opening wall 18 a of the bellows 18. The inner space of the casing 17 is formed in the bellows 18 through the communication check passage 16 formed through the discharge check valve 16 b of the pump section 4 and the thickness of the partition wall 1 by being pressed and fixed to the other side surface in an airtight manner. A liquid chamber 20a for temporarily storing the liquid discharged through the chamber is separated from an air chamber 20b outside the bellows 18 in which air for suppressing pulsation is sealed.

The closed end 18b of the bellows 18 is provided at the center thereof with a cylindrical connecting member 22 which is oriented in the direction of increasing the capacity of the liquid chamber 20a, that is, in the direction of extension of the bellows 18.
Is pressed by the elastic force of the spring 23,
The pulsation suppressing unit 5 configured to absorb pulsation due to the discharge pressure of the liquid discharged from the pump action chamber 9a of the pump unit 4 due to the change in the capacity of the liquid chamber 20a due to the expansion and contraction deformation of the bellows 18 is configured by the above components. Have been.

A supply / exhaust switching valve mechanism 24 is provided on the outer surface of the bottom wall 17a of the bottomed cylindrical casing 17 in the pulsation suppressor 5. The supply / exhaust switching valve mechanism 24 is configured as shown in FIG. In FIG. 2, reference numeral 25 denotes a bottomed cylindrical casing.
A slide valve body 27 is fitted into the cylinder portion 26 housed in the cylinder 5 so as to be slidable along the axial direction. 28 is a bottom wall 17a of the bottomed cylindrical casing 17
The operation rod is inserted through the hole 17b formed in the air chamber 20b into the air chamber 20b. One end of the operation rod is coaxially connected to one end of the slide valve body 27. The connecting flange 28a on the other end is connected to a reference position in the cylindrical connecting member 22.

On the peripheral wall of the casing 25, an air supply port 29 is formed near the bottom wall 17a of the casing 17, and an exhaust port 30 is formed near the other side. The air supply port 29 is configured to supply air having a pressure equal to or higher than the maximum pressure value of the transfer liquid.
The exhaust port 30 is open to the atmosphere. These air supply ports 29
Ports 31 and 32 are formed on the peripheral wall of the cylinder portion 26 corresponding to the exhaust port 30. A supply / exhaust passage 33a formed in the peripheral wall of the casing 25 communicates the air chamber 20b with the inside of the cylinder portion 26. 33b is an air chamber 2 through the supply / exhaust passage 33a.
0b, flange 28a, cylinder 26, and casing 25
It is a passage that communicates the area surrounded by. This passage 33
With b, the effect of the air pressure in the air chamber 20b acting on the slide valve body 27 can be canceled, and the pressure of the transfer liquid can be accurately transmitted to the slide valve body 27.

The slide valve body 27 is provided with three sliding flanges 27a, 27b, at predetermined intervals in the axial direction thereof.
27c, an air supply space S1 is formed between the center flange 27b and the one end flange 27c, and an exhaust space S is formed between the center flange 27b and the other end flange 27a.
2. The slide valve body 27 is configured such that the capacity of the liquid chamber 20a increases in a predetermined range A due to a change in the pump discharge pressure.
When the pressure exceeds the range, the supply / exhaust passage 33a communicates with the space S1, and when the capacity reduction of the liquid chamber 20a exceeds a predetermined range B, the supply / exhaust passage 33a communicates with the space S2. Have been. 34 is the casing 25
A spring member that is installed in the inside and biases the slide valve body 27 upward to hold the slide valve body 27 at the reference position.

In the pump for a semiconductor manufacturing apparatus having the above-described structure, the bellows 7 in the pump section 4, the bellows 18 in the pulsation suppressing section 5, the partition wall 1, the casings 6, 17, and the suction check valve 16a. The movable valve bodies 16a1 and 16b1 of the discharge check valve 16b are made of a fluorine resin material such as PTFE and PFA, which are excellent in corrosion resistance and heat resistance, and the outer surfaces of both casings 6 and 17 are made of aluminum Teflon. Coat is given. The annular fixing plates 8 and 19 in the pump section 4 and the pulsation suppressing section 5 are made of FRP such as unsaturated polyester containing glass fiber. Further, in FIG. 1, 35a and 35b are
Is a proximity sensor attached to the air cylinder section 14 of the cylinder body 11 for pressurized air supplied from a pressurized air supply device (not shown) such as a compressor.
The supply to the inside and the supply to the pump working chamber 9b are automatically switched.

Next, the operation of the pump for a semiconductor manufacturing apparatus having the above configuration will be described. When the pressurized air supplied from a pressurized air supply device (not shown) such as a compressor is supplied to the inside of the cylinder body 11 of the air cylinder section 14 to extend the bellows 7 in the x direction in FIG. The transfer liquid in the passage 2 passes through the check valve 16a for suction through the pump action chamber 9
When the bellows 7 is contracted in the y direction in FIG. 1 by supplying the pressurized air into the pump working chamber 9b of the air cylinder portion 14 and then sucked into the pump working chamber 9a. The bellows 7 of the reciprocating pump unit 4 is driven and expanded and contracted via the air cylinder unit 14 so that the transfer liquid is discharged through the discharge check valve 16b, thereby moving the suction check valve 16a. Valve body 16a
And the movable valve body 16b1 of the discharge check valve 16b alternately opens and closes, so that the suction of the liquid from the inflow passage 2 to the pump action chamber 9a and the discharge of the liquid from the inside of the pump action chamber 9a to the outflow passage 3 The predetermined pump action is repeated. When the transfer liquid is fed toward a predetermined portion by the operation of the reciprocating pump unit 4, the pump discharge pressure generates pulsation due to repetition of peaks and valleys.

The transfer liquid discharged from the pump action chamber 9a of the reciprocating pump section 4 through the discharge check valve 16b is sent through the communication path 21 to the liquid chamber 20a of the pulsation suppression section 5. The liquid is temporarily stored in the liquid chamber 3 and then flows out to the outflow passage 3. At this time, when the discharge pressure of the transfer liquid is at the peak of the discharge pressure curve, the transfer liquid expands and deforms the bellows 18 so as to increase the capacity of the liquid chamber 20a, so that the pressure is absorbed. At this time, the liquid chamber 20
The flow rate of the transfer liquid flowing out from a is smaller than the flow rate sent from the pump unit 4.

Further, when the discharge pressure of the transfer liquid approaches the valley of the discharge pressure curve, the pressure of the transfer liquid becomes lower than the sealing pressure in the compressed air chamber 20b due to the expansion deformation of the bellows 18. The bellows 18 contracts and deforms. At this time, the flow rate flowing out of the liquid chamber 20a is larger than the flow rate of the transfer liquid flowing into the liquid chamber 20a from the pump unit 4. The pulsation is absorbed and suppressed by the repetitive operation, that is, the change in the capacity of the liquid chamber 20a.

By the way, during the above operation,
When the discharge pressure from the pump section 4 rises and fluctuates, the volume of the liquid chamber 20a increases due to the liquid to be transferred, and the bellows 18 is greatly expanded and deformed. When the amount of extension deformation of the bellows 18 exceeds a predetermined range A, the slide valve body 27 is slid outwardly via the operating rod 28, and the supply / exhaust passage 33a
Is communicated with the air supply port 29 via the space S1. For this reason, high air pressure is supplied from the air supply port 29 to the air chamber 20b via the space S1 and the passage 33a.
The sealing pressure of b is increased, whereby the amount of expansion deformation of the bellows 18 is restricted, and the capacity of the liquid chamber 20a is prevented from being excessively increased.

On the other hand, when the discharge pressure from the pump section 4 fluctuates, the capacity of the liquid chamber 20a is reduced by the transferred liquid,
The bellows 18 is greatly contracted and deformed. When the amount of contraction deformation of the bellows 18 exceeds a predetermined range B, the slide valve body 27 slides inward via the operating rod 28, and the supply / exhaust passage 33a communicates with the exhaust port 30 via the space S2. Is done. For this reason, the sealed air a in the air chamber 20b flows through the air supply / exhaust passage 33a and the space S2 so that the air outlet 30
From the air chamber 20b to reduce the sealing pressure of the air chamber 20b, thereby restricting the amount of contraction and deformation of the bellows 18 and suppressing the capacity of the liquid chamber 20a from excessively decreasing. As a result, the pulsation can be efficiently absorbed and the pulsation width can be reduced, regardless of the fluctuation of the discharge pressure from the pump action chamber 9a of the pump section 4.

In the pump for a semiconductor manufacturing apparatus that operates as described above, the reciprocating pump unit 4 and the pulsation suppressing unit 5 are integrated, and an external piping such as a tube made of a fluorine resin for connecting the two. Is not required, not only can the cost and size of the entire pump be reduced and the installation space can be significantly reduced, but also the piping can be broken by prolonged use due to the omission of external piping. Since there is no danger of liquid leakage, etc., and there are very few places that cause pressure loss, it is possible to reduce the pump capacity to make the whole more compact and to reduce the installation area. It is possible.

By providing the supply / exhaust switching valve mechanism 24 as described in the above embodiment outside the pulsation suppressor 5, even if the supply / exhaust switching valve mechanism 24 breaks down, the pump is operated. The side can easily perform maintenance such as repair and replacement of parts only for the air supply / exhaust switching valve mechanism 24 without any disassembly, etc., especially for semiconductor manufacturing that handles strongly acidic or strongly alkaline chemicals. Useful as a pump for the device. Furthermore, when a cylindrical valve mechanism using the slide valve body 27 is used as the supply / exhaust switching valve mechanism 24 as in the above-described embodiment, the size can be reduced, and the communication structure with the air chamber 20b can be achieved. It has the advantage of being simple.

[0030]

As described above, according to the first and second aspects of the present invention, the reciprocating pump portion and the pulsation suppressing portion are integrated and an external pipe such as a tube for connecting the two. Not only not only can the overall cost be reduced and the size reduced, but also a significant reduction in installation space can be achieved. There is no danger of occurrence, and the safety in use can be ensured.The pressure loss is also very small, so the pump capacity can be reduced accordingly and the size can be further reduced, and the pump installation area can be reduced. It is possible to achieve the effect of reducing the size.

According to the third aspect of the present invention, in addition to the above-described effects, the movement of the reciprocating body is restricted to a certain range regardless of the fluctuation of the discharge pressure from the reciprocating pump, and the pulsation width is reduced. It can be further reduced.

[Brief description of the drawings]

FIG. 1 is an overall vertical sectional front view of an air-driven bellows type pump applied as an embodiment of a pump for a semiconductor manufacturing apparatus according to the present invention.

FIG. 2 is an enlarged vertical sectional front view of a main part of the pump.

FIG. 3 is an overall vertical sectional front view of a conventional pump for a semiconductor manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Partition wall 2 Inflow path 3 Outflow path 4 Reciprocating pump part 5 Pulsation suppression part 6,17 Casing 7,18 Bellows 9a Pump working chamber 14 Air cylinder part 16a Suction check valve 16b Discharge check valve 16a1,16b1 Movable Valve body 16a2, 16b2 Spring 20a Liquid chamber 20b Air chamber 24 Supply / exhaust switching valve mechanism 27 Slide valve body 28 Operating rod 33a Supply / exhaust passage

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mutsui Fujii 541-1, Shimouchi Shinto bat, Mita City, Hyogo Prefecture Inside the Mita Plant of Nippon Pillar Industry Co., Ltd. (72) Inventor Yoji Minato Shimouchi God, Mita City, Hyogo Prefecture No. 541, a character hitting ground In the Mita factory of Nippon Pillar Industry Co., Ltd. (56) References JP-A-8-159016 (JP, A) JP-A-5-240161 (JP, A) JP-A 8-121342 (JP) JP-A-48-18803 (JP, A) JP-A-61-275589 (JP, A) JP-A-7-27043 (JP, A) JP-A-6-47675 (JP, U) JP-A-6-47675 2-119985 (JP, U)

Claims (3)

(57) [Claims] 1. A partition wall having an inflow path and an outflow path for a liquid, a bellows that expands and contracts in a casing fixedly connected to one side of the partition wall, and causes the bellows to drive and expand and contract. A pump action chamber provided with a check valve comprising a movable valve body and a spring, which alternately open and close in accordance with the expansion and contraction movement of the air cylinder portion and the bellows to perform a liquid suction operation and a discharge operation. And a reciprocating pump portion, which is disposed in a casing fixedly connected to the other side of the partition wall so as to face the bellows of the reciprocating pump portion, and is capable of expanding and contracting in the direction of expansion and contraction of the bellows. A bellows, a liquid chamber formed on one side of the bellows and capable of temporarily storing liquid discharged from a pump working chamber of the reciprocating pump section through a discharge check valve, and a liquid chamber on the other side of the bellows. To An air chamber in which a pulsation suppressing gas is sealed and formed, and discharge of liquid discharged from a pump working chamber of the reciprocating pump unit due to a change in the capacity of the liquid chamber accompanying expansion and contraction movement of the bellows. And a pulsation suppressor configured to absorb pulsation due to pressure. A pump for a semiconductor manufacturing apparatus, comprising: 2. The partition wall, the casing in the reciprocating pump section and the pulsation suppressing section, the movable valve bodies of the suction and discharge check valves in the reciprocating pump section, and the bellows and the pulsation suppressing section in the reciprocating pump section. Bellows,
2. The pump according to claim 1, wherein the pump is made of a fluorine resin material such as PTFE or PFA. 3. An operating rod inserted into the air chamber and capable of responding to the expansion and contraction movement of the bellows,
When the capacity of the liquid chamber increases beyond a predetermined range through the supply / exhaust passage which is operated by the operating rod and communicates with the air chamber, the supply port and when the capacity of the liquid chamber decreases beyond the predetermined range. 3. The pump for a semiconductor manufacturing apparatus according to claim 1, further comprising a supply / exhaust switching valve mechanism provided with a valve body selectively communicating with the exhaust port.