JPH0463975B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for controlling humidity in a clean room, and particularly to a method for controlling humidity in a clean room for creating a clean working environment required for semiconductor manufacturing and the like.

[Conventional technology] In recent years, the number of areas that require dust management in the production process, such as the semiconductor industry and precision industry, has rapidly increased.
Along with this, construction of clean rooms is being actively carried out.

FIG. 2 is an explanatory diagram showing the structure of a conventional clean room. As shown in FIG. 2, the clean room 10 has an outer room 12 and an inner room 14.
Inside 4 is clean room 15. A ceiling chamber is formed between the upper surface of the outer chamber 12 and the upper surface of the inner chamber 14, and on the upper surface of the inner chamber 14, a plurality of fan filter units 16, 16, . will be arranged. Clean air is supplied from these fan filter units 16 into the clean room 1.
5 is blown out. After the blown air flows down, it passes through the grating floor surface (ventilation surface) 18 and is sucked into the underfloor chamber 20. The underfloor chamber 20 is formed between the grating floor 18 and the foundation floor of the outer room 12.

Air in the underfloor chamber 20 is sent to an air conditioner 26 via a suction port 22 and a wind conduit 24. Inside the air conditioner 26 there is a spray type humidifier 28 and a cooler 3.
0, a heater 32 and a filter 34 are provided, and after the air from the underfloor chamber 20 is temperature and humidity controlled by these devices, it passes through a wind pipe 36 and an air supply fan 38 to the fan filter units 16, 16.
Air is blown to... After the blown air is made into clean air by the fan filter unit 16, it is blown out again into the clean room 15 and circulated.

In addition, a spray type humidifier 28 in the air conditioner 26
The ultrapure water from the ultrapure water production device 40 is pumped to the pump 4.
2 and the control valve 44, and the ultrapure water is sprayed from the nozzle of the humidifier 28. The air from the underfloor chamber 20 comes into gas-liquid contact with the sprayed ultrapure water and is humidified by evaporation. The ultrapure water regulating valve 44 is controlled by a controller 46, and the controller 46 controls the regulating valve 44 based on the measured value of the humidity sensor 48 in the clean room 15.

Such ultrapure water is particularly required for air conditioning in clean rooms. If ordinary city water is used, it will contain various impurities, so impurities will be mixed into the air due to humidification, and the fan filter unit 16
This speeds up the clogging of the high-performance filter inside the clean chamber 15, and has a negative impact on maintaining the cleanliness inside the clean chamber 15. Therefore, ultrapure water (1,000 to 2,000 yen/m ^{3 ,} which is 5 to 10 times more expensive than city water) is used, which is expensive to produce.

In addition, the air from the underfloor chamber 20 is supplied to the wind pipe 24.
A portion of the gas is discharged from an exhaust pipe 50 branched from the exhaust pipe 50. Further, a part of the outside air is blown to the air conditioner 26 from the wind pipe 24 through the outside air inlet 52 and the outside air processing air conditioner 54 .

In such a configuration, clean air is supplied to the air conditioner 2.
6, the air is cleaned by a high-performance filter of a fan filter unit 16, and blown into the clean room 15. Control device 46
The ultrapure water control valve 44 is adjusted based on the measured value of the humidity sensor 48 in the clean room 15, and the amount of ultrapure water sprayed by the spray type humidifier 28 is adjusted. Thereby, the humidity of the clean air blown out is adjusted by the control device 46.

The clean air is conventionally controlled so that the humidity in the clean room 15 is maintained at 40 to 45% (RH).
If the humidity in the clean room 15 exceeds 45%, quality problems will occur in the manufacturing process of semiconductor resists and the like. Furthermore, if the humidity of clean air is extremely reduced, a strong charge will be generated on the inner wall surface or process equipment of a conventional clean room, and dust will adhere to these and tend to accumulate in the clean room 15. For this reason, there is a problem that the cleanliness in the clean chamber 15 decreases and the amount of dust adhering to the workpiece increases. Further, since such static electricity reaches 60 to 100 volts, it induces an environment that causes electrostatic damage to semiconductor RAMs and the like manufactured in the clean room 15. Therefore, the humidity in the clean room 15 is maintained at 40% or higher.

[Problem that the invention seeks to solve]

However, with recent remarkable developments in material technology, particularly in antistatic technology, interior materials used in clean rooms that are more difficult to charge than conventional materials have come to be used. For this reason, there is no need to maintain the humidity in the clean room 15 at 40% or higher as in the past.
There is no problem even if the humidity is lowered to a level that corresponds to the electrostatic potential generated in the interior materials used.

However, in conventional clean room humidity control methods, although it is possible to lower the humidity by improving interior materials, etc., clean air is
Based on this, the humidity in the clean room 15 is controlled so that it is always maintained at 40% or higher. Therefore, there is a problem that ultrapure water, which is expensive to manufacture, is used excessively in the humidifier 28 of the air conditioner 26, and the running cost of the humidifier 28 is also wasted.

The present invention was developed in light of these circumstances, and proposes a clean room humidity control method that adjusts the humidity inside a clean room at low cost without affecting the products to be manufactured during semiconductor manufacturing, in line with recent antistatic technology. It is intended to.

[Means for solving problems]

In order to achieve the above object, the present invention provides a method for controlling humidity in a clean room in which the humidity of clean air blown into the clean room is controlled using pure water, in which the charged potential of objects installed in the clean room is measured. The method is characterized in that the humidity of the clean air is adjusted based on the measured value.

[Effect]

According to the clean room humidity control method according to the present invention, the charged potential of objects such as structures or process equipment in the clean room is measured, and the humidity of the clean air is adjusted based on the measured value. For this reason, it is not necessary to keep the humidity in the clean room at 40% as in the past.
% or higher, the air can be supplied with the humidity of the clean air reduced as much as possible based on the charged potential value. Therefore,
By lowering the humidity of clean air, the amount of pure water used is reduced, and there is no waste in operating costs for controlling the humidity.

〔Example〕

Preferred embodiments of the method for controlling humidity in a clean room according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing a method for controlling humidity in a clean room according to the present invention. The clean room 11 shown in FIG. 1 has approximately the same configuration as the conventional clean room 10 shown in FIG. 2, and parts or components similar to those of the clean room 10 shown in FIG. Therefore, detailed explanation will be omitted.

Clean room 1 of clean room 11 according to the present invention
5 is provided with a charging electrometer 70;
The potential measurement value of the structure measured at 0 is the control device 7
2 is input. The control device 72 is a charging electrometer 70
Pure water control valve 4 based on the charged potential value measured in
4 adjustments are being made. Note that structures such as the inner walls of the clean room 15 are coated with antistatic paint, etc., unlike conventional ones, and when the charged potential is 50 volts, the humidity in the clean room 15 is 40% RH or less. This is when the humidity is low.

According to the clean room humidity control method according to the present invention configured as described above, the control device 72 adjusts the pure water control valve 44 based on the potential measurement value of the charged electrometer 70, and controls the spray amount in the humidifier 28. is being adjusted. The adjustment is set so that the measured value of the charged electrometer 70 in the clean room 15 does not exceed 50 volts. Therefore, the clean air blown out from the fan filter unit 16 is
The humidity in the clean room 15 is controlled to the extent that the structure in 5 has a charged potential of 50 volts or less, and the humidity in the clean room 15 is higher than before.
Can be kept below 40%RH. Therefore, the humidity of the clean air is lower than before, the amount of ultrapure water required for humidification by the spray humidifier 28 is reduced, and the operating cost of the humidifier 28 is also reduced. Furthermore, since products are manufactured at lower humidity than in the past, the products to be manufactured are not adversely affected by humidity and yields are improved.

In the embodiment described above, only one charged electrometer 70 was provided on the inner wall surface of the clean room 15, but the invention is not limited to this, and a plurality of charged electrometers may be provided on the inner wall or process equipment, etc., for fine-grained humidity control. You may do so.

Further, in the embodiment described above, the control device 72 was controlled based only on the charging electrometer 70 in order to control the humidity. However, in addition to this charged electrometer 70, a humidity sensor 48 may be provided in the clean room 15. Humidity sensor 48 measures the humidity in clean room 15 and outputs the measured value to control device 72 . As a result, the control device 72 uses not only the measured value based on the charging electrometer 70 but also the measured value based on the humidity sensor 48 to set an upper limit so as not to reach a humidity of 45% or more, which would have an adverse effect on the semiconductor. Can be safely controlled.

Although the spray type humidifier 28 was used in the embodiment, the present invention is not limited to this, and any type of humidification control method may be used as long as the humidification can be controlled.

〔Effect of the invention〕

As explained above, in the clean room control method according to the present invention, the charged potential generated on objects in the clean room is measured and the humidity of the clean air is adjusted based on the measured value of the charged potential. Humidification can be performed at low cost without requiring a large amount of pure water or the like. Furthermore, the products to be manufactured are manufactured in as good an environment as possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a clean room control method according to the present invention, and FIG. 2 is an explanatory diagram of a conventional clean room control method. 11...Clean room, 12...Outside room, 14
...Inner room, 15...Clean room, 16...Fan filter unit, 18...Grating floor, 20
... Underfloor chamber, 26 ... Air conditioner, 28 ... Spray type humidifier, 40 ... Ultrapure water production device, 4
2... Pump, 44... Pure water control valve, 48... Humidity sensor, 70... Charging electrometer, 72... Control device.

Claims (1)

[Claims] 1. A method for controlling humidity in a clean room that uses pure water to control the humidity of clean air blown into the clean room, comprising: measuring the charged potential of objects installed in the clean room; A clean room humidity control method characterized by adjusting the humidity of clean air based on the humidity value. 2. A humidity sensor is provided in the clean room,
Claim 1, characterized in that an upper limit of humidity in the clean room is set based on the humidity measurement value of the humidity sensor, and the humidity of the clean air is controlled so that the humidity in the clean room is maintained below the upper limit value. Clean room humidity control method described.