Refrigeration – Disparate apparatus utilized as heat source or absorber
Reexamination Certificate
2000-09-27
2002-04-16
Esquivel, Denise L. (Department: 3744)
Refrigeration
Disparate apparatus utilized as heat source or absorber
C165S104330
Reexamination Certificate
active
06370897
ABSTRACT:
TECHNICAL FIELD
The present invention relates to semiconductor manufacturing facilities and, more particularly, to a semiconductor manufacturing facility having a heat recovery apparatus, which recovers heat generated by semiconductor manufacturing equipment.
BACKGROUND ART
In a semiconductor manufacturing plant, boilers and refrigerating machines are installed so as to serve as cold heat sources for air conditioning. In order to attempt energy conservation in the semiconductor manufacturing plant, it is required to reduce operation loads of the boilers and the refrigerating machines. For example, it is considered to use a method of saving a power consumed by a refrigerating machine by reducing a load to the refrigerating machine, which supplies a refrigerating medium to a dry coil, by reducing an amount of air supplied to a clean room or reducing an amount of air circulating in the clean room so as to reduce an amount of heat removed by the dry coil to cool the air circulating in the clean room. However, this method has a problem in that the temperature of the clean room cannot be adjusted in a case in which the temperature of the clean room is increased due to heat generated by semiconductor manufacturing equipment.
In the conventional class 10 clean room (particle diameter of 0.1 &mgr;m), the number of circulations is 100 times per one hour. The reason for such a large number of circulations is not only to remove dust but also to maintain the temperature of the clean room at 23° C. That is, it is necessary to remove heat by the heat exchange in the dry coil. If the number of times of the circulation is reduced, the temperature fluctuation in the clean room may not be controlled under certain operating conditions of the semiconductor manufacturing apparatus. As a result, there also is a problem in that an yield rate of the products is decreased since the dimensional deviation of machining is increased due to a temperature change of the semiconductor manufacturing equipment which needs a temperature control due to its property.
Accordingly, in view of saving the air conditioning energy in the semiconductor manufacturing plant, it is preferable for the conventional facility to increase the setting temperature of the clean room as high as possible. However, an environment of a temperature exceeding 23° C. is an operating environment in which a worker wearing clean clothes in the clean room feels hot. Additionally, natrium or ammonium is generated due to sweating of the worker, which may deteriorate the working environment. Accordingly, in view of the working environment, it is not preferable to increase the setting temperature of the clean room to a temperature above 23° C.
In view of the above mentioned, it is said that the method of reducing the number of times of circulation in the clean room or a method of increasing the setting temperature of the clean room is not a decisive plan to achieve the energy saving.
A description will now be given of a conventional apparatus for cooling the semiconductor manufacturing equipment.
FIG. 1A
is a perspective view of a single coil cooing pipe
10
conventionally used to cool a heating furnace (specifically, a heat generating part thereof) of the semiconductor manufacturing equipment.
FIG. 1B
is a front view of the cooling pipe
10
. The cooling pipe
10
is wound on the periphery of the semiconductor manufacturing equipment, and cooling water is supplied to a lower cooling water inlet port
11
. The cooling water flows through a coil portion, and exit from an upper cooling water outlet port
12
. Release of heat to outside (inside the clean room) is suppressed by the cooling water recovering the heat of the semiconductor manufacturing equipment.
The temperature of the cooling water supplied to the cooling water inlet port
11
is maintained at about 23° C., which is a setting temperature of a clean room so that dew formation does not occur. The temperature of the cooling water exiting from the cooling water outlet port
12
normally ranges from about 25° C. to 28° C. although the temperature varies according to the operating conditions. That is, a temperature difference between the cooling water inlet port
11
and the outlet port
12
is about 5° C.
A description will now be given, with reference to
FIG. 2
, of a cooling system of the cooling water supplied to the cooling pipe
10
. Cold water of about 6° C., which is cooled by a refrigerating machine
101
, is temporarily stored in a cold-water tank
102
, and is delivered to a heat exchanger
103
. The cold water delivered to the heat exchanger
103
cools the cooling water to be supplied to the coil-type cooling pipe
10
, and, thereafter, returned to the cold-water tank
102
. On the other hand, the cooling water stored in a buffer tank
104
, which has a temperature higher than 23° C., is delivered to the heat exchanger
103
by a water pump
105
, and is cooled to the temperature of 23° C. by exchanging heat with the cold water of 6° C. The cooling water enters the inlet port
11
of the coil-type cooling pipe
10
, passes through the cooling pipe
10
and exits from the outlet port
12
so as to be returned to the buffer tank
104
. It should be noted that, in
FIG. 2
,
106
indicates a cooling tower,
107
indicates a temperature sensor, and
108
-
110
indicate water pumps.
In the above-mentioned cooling apparatus, since the temperature at the outlet port of the cooling pipe
10
is as low as below 30° C., a temperature difference between the air or water with which heat is exchanged is small. Accordingly, the heat exchange efficiency is low, and the cooling water was not able be used for heat recovery. Additionally, since the temperature of the cooling water supplied to the cooling pipe
10
is set to the setting temperature of 23° C. of the clean room, the cooling water of a separate system must be controlled to about 23° C. by heat exchange by the heat exchanger
103
using the cold water of about 6° C. produced by the refrigerating machine
101
. Accordingly, the refrigerating machine
101
and the heat exchanger
103
are needed, thereby increasing a thermal energy loss, and, additionally, since two cooling water delivery lines are needed, a separate water pump must be provided to each of the lines. As a result, there is a problem in that an area occupied by the facility is increased, and a facility equipment cost is increased.
In the above-mentioned cooling system, an amount Q of heat absorbed by the cooling water from the heat source (semiconductor manufacturing apparatus
1
) is represented by the following equation (1), where amount of cooling water is W, specific heat is Cw, inlet temperature is Ti, outlet temperature is TO and temperature difference between inlet and outlet is &Dgr;T.
Q=W·Cw·(TO−Ti)=W·Cw·&Dgr;T (1)
In the equation (1), since the specific heat Cw s constant and the temperature difference &Dgr;T is as small s about 5° C., the amount W of cooling water must be increased so as to increase the amount Q of heat absorbed by the cooling water. Accordingly, a large amount of cooling water is needed, and there is a problem in that a power cost of the pump is increased. Additionally, since the cooling water is supplied to the cooling water coil
10
by a full operation of the pump even in a steady state, an insufficient cooling occurs when the temperature at the outlet port
12
is rapidly increases due to a rapid increase of the load during the operation of the apparatus.
Additionally, a micro vibration is generated due to an inevitable increase in the amount of cooling water flowing through a main water delivery pipe due to a large amount of cooling water flowing through the cooling pipe. If the generated micro vibration propagates the clean room structure, which is a support member of a water delivery main pipe, a bad influence is exerted on an exposure machine and a scanning electron microscope, which are sensitive to a vibration are installed in a process area. In addition to those problems, there also is a pro
Kobayashi Sadao
Ohmi Tadahiro
Suenaga Osamu
Esquivel Denise L.
Jiang Chen-Wen
Pillsbury & Winthrop LLP
Tokyo Electron Limited
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