JP3376600B2 - Atmosphere analysis method and analyzer, and clean room atmosphere control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmosphere analysis method and analysis apparatus, and a clean room atmosphere control apparatus.

Impurities in a clean room are impurities that are conventionally captured as particles, and techniques for measuring them and air conditioning techniques for controlling them have been developed.

However, in recent years, with the advancement of semiconductor device manufacturing processes, ionic components present in the air in a very small amount have come to be regarded as a problem. The ionic components include impurity ions such as Na ⁺ , and impair the reliability of the manufactured semiconductor device.

Therefore, it is required to analyze such components contained in the clean room atmosphere and take measures to suppress the amount.

[0005]

2. Description of the Related Art Conventionally, there are the following methods for analyzing ionic components in air. A method for directly analyzing components in the air by gas chromatography.

A method of analyzing the pure water by bubbling the pure water and passing air to dissolve the components in the air. However, these methods have the following problems. That is, it is extremely difficult to measure an ionic component (for example, several ng in 1 m ³ ) that exists in the air in a very small amount, and it takes several hours to several tens of hours to dissolve it in pure water. Forced contact with air is required and real-time measurement is not possible.

Therefore, it is necessary to develop a method for measuring in real time the ionic components that are present in the air in a very small amount.

[0008]

In view of the above problems, the present invention develops a method for dissolving components in air in pure water, and provides a new analysis method and analysis apparatus for directly extracting water from an atmosphere for analysis. The present invention further provides a control device for suppressing the ionic components in the clean room atmosphere to be below a certain value.

[0009]

FIG. 1 is a diagram for explaining an atmosphere analyzer, FIG. 2 is a diagram for explaining a clean room atmosphere control method (No. 1), and FIG. 3 is a clean room atmosphere control method (No. 2). It is a figure explaining.

The above-mentioned problem is caused by the room temperature atmosphere in a clean room.
Is continuously collected and cooled, and the resulting condensed water is collected.
Then , the problem is solved by an atmosphere analysis method in which impurities contained in the condensed water are analyzed at any time .

In addition, the room temperature atmosphere of the clean room is always maintained.
Means for continuous sampling and cooling for cooling the sampled atmosphere
And the drain that collects the condensed water generated in the cooling unit.
Receiver and analyzer for analyzing impurities contained in the condensed water
And an atmosphere analyzer having .

Further, the above-mentioned atmosphere analyzer, the first air amount adjusting valve 13 provided in the outside air supply path 12 for supplying outside air to the clean room 11, and the air discharged from the clean room 11 When the amount of impurities by the second air amount adjusting valve 16 provided in the return path 15 for returning to the return path 15 and the analyzer exceeds a preset amount, the ratio of the return path 15 air volume to the outside air supply path 12 air volume The control device for the clean room atmosphere has the second air amount adjusting valve 16 and / or the input / output conversion unit 17 for operating the first air amount adjusting valve 13 so as to lower the temperature.

Also, the above-mentioned atmosphere analyzer, the first air amount adjusting valve 22 provided in the return main path 21 for returning the air discharged from the clean room 11 to the clean room 11, and the return main path 21. A second air amount adjusting valve 25 provided in parallel with a part of the above, and provided in the return sub-path 23 partially filled with the impurity adsorbent 24, and the amount of impurities by the analyzer is set in advance. When there are more,
The first air amount adjusting valve 22 and the second air amount adjusting valve 22 and the second air amount adjusting valve 22 so as to reduce the ratio of the air volume of the return main route 21 to the air amount of the return sub route 23.
This is solved by the control device for the clean room atmosphere having the input / output conversion unit 26 for operating the air amount adjusting valve 25 of FIG.

[0014]

FIG. 4 is a diagram for explaining dew condensation from an atmosphere containing water, showing the amount of water retained in air with respect to temperature. Curve a is for air containing saturated steam, and curve b is for air containing unsaturated steam.

When the air containing unsaturated steam is cooled from the temperature T ₁ , it reaches saturation at the temperature T ₂ , and when it is further cooled, excess water is condensed. At temperature T ₃ , (x ₁ −
The excess water of x ₂ ) is condensed.

Therefore, by cooling the atmosphere, the moisture contained in the atmosphere is condensed to obtain condensed water. Since the condensed water dissolves the impurities in the atmosphere, the impurities contained in the atmosphere can be analyzed by analyzing the impurities contained in the condensed water.

The atmosphere in the clean room has, for example, a temperature of 2
4 ℃, water content is adjusted to 45% of saturated water vapor,
When it is cooled, it reaches saturation at 11.5 ° C. Therefore, if this atmosphere is brought into contact with the cooling section (pipe) 3 through which cooling water of 6 ° C. flows, for example, dew condensation water 2 is generated on the outer surface of the cooling section 3.

If the condensed water 2 is received by the drain receiver 4a and the impurities contained in the condensed water 2 are analyzed by the analyzer 7, the impurities contained in the clean room atmosphere can be continuously analyzed in real time. At this time, if the surfaces of the cooling unit 3 and the drain receiver 4a are made of quartz or a polymer material, impurities do not enter the condensed water 2 from the cooling unit 3 and the drain receiver 4a, so that the analysis accuracy is improved.

In order to save the supply of outside air to the clean room 11 during the operation of the clean room, the clean room
The air discharged from 11 is partially returned to the clean room 11, but when pollution in the clean room 11 progresses, the ratio of the return air amount and the outside air supply amount must be adjusted to reduce the pollution. . Therefore, the atmosphere analyzer 7, the first air amount adjusting valve 13 in the outside air supply path 12, the second air amount adjusting valve 16 in the return path 15,
An input / output conversion unit 17 is provided to reduce the ratio of the return passage 15 air volume to the outside air supply passage 12 air volume by the input / output conversion unit 17 when the amount of impurities by the atmosphere analyzer 7 exceeds a preset amount. Then, the second air amount adjusting valve 16 and / or the first air amount adjusting valve 13 are operated. This suppresses contamination of the clean room atmosphere.

Further, in order to reduce the pollution when the inside of the clean room 11 is advanced, the first air amount adjusting valve 22 is provided in the return main path 21 and a part of the return main path 21 is provided in parallel. Impurity adsorbent 24 loaded return sub-path
23 is provided with a second air amount adjusting valve 25 and an input / output converter 26,
When the amount of impurities by the atmosphere analyzer 7 becomes larger than a preset amount, the first air amount adjusting valve is set by the input / output conversion unit 26 so as to reduce the ratio of the return main route 21 air amount to the return sub route 23 air amount. 22 and second air amount adjusting valve 25
To operate. This suppresses contamination of the clean room atmosphere.

[0021]

EXAMPLES FIGS. 1 (a) and 1 (b) are views for explaining an atmosphere analyzer, (a) shows an overall view, (b) shows a cooling dehumidifier, 1 is sampled air, and 2 is dew condensation. Water, 3 is a cooling unit and a cooling pipe, 4a is a drain receiver, 4b is a water trap, 4c is a condensed water outlet, 5 is a fan, 6 is a filter, 7 is an analyzer, 8 is a computer, 9 is a display Represents

The sampled air 1 has, for example, a clean room atmosphere. The drain receiver 4a receives the dew condensation water attached to the outer wall of the cooling pipe 3 and forms a water seal trap 4b. The cooling pipe 3, the drain receiver 4a, and the water seal trap 4b are made of quartz or a polymer material such as Teflon. Alternatively, it is coated with a polymer material. By doing so, the accuracy of analysis is improved. If the cooling pipe 3, the drain receiver 4a, and the water seal trap 4b are made of metal, there is a high possibility that a very small amount of metal will be taken into the dew condensation water, and the analysis accuracy will decrease.

The analysis device is, for example, an ion chromatography analysis device, an atomic absorption analysis device, or an ICP emission analysis device. The analysis value output of the dew condensation water is sent to the computer 8 and the state of the clean room is monitored and judged.

The dehumidified air is directly exhausted by the fan 5 or returned to the clean room through the filter 6.
An example of analyzing a clean room atmosphere using this analyzer will be described. Room temperature 24 ° C, relative humidity 45
%, Clean room atmosphere adjusted to 6%
The condensed water 2 was obtained by cooling with a cooling pipe through which the cooling water of FIG.

The condensed water 2 was analyzed by ion chromatography. Table 1 shows the concentrations of various ions in dew water at that time.
Shown in. Further, Table 1 shows the corresponding concentrations in air. The relationship between the concentration in condensed water and the concentration in air was determined by preliminary experiments.

[0026]

Table 1 An example condensation water concentration (ppb) in the air concentration of the analysis results of the clean room atmosphere ^{(μg / m 3) Na 5.7} 0.057 Zn 18.1 0.18 NH 4 + 220.9 2.2 F - 35.1 0.35 Cl - 46.2 0.46 NO 2 - 120.5 1.2 _{^{NO 3 - 110.5 1.1 SO 4 2-}} 9.2 0.092 PO 4 3- 8.0 0.08 2 is a diagram illustrating a control method for a clean room atmosphere (Part 1), 1 air taken, 10 analyzer of the above atmosphere, 11 is a clean room, 12 is an outside air supply path, 12a
Is an external air conditioner, 13 is an air amount adjusting valve, 14 is an air conditioning supply path, 14a
Is an air conditioner, 15 is a return path, 16 is an air quantity adjusting valve, 17 is an input / output conversion unit, 18 is an exhaust path, 18a is a fan, and 19 is an air quantity adjusting valve. Furthermore, A is the amount of air in the outside air supply path, and B is
Is the air volume of the return path, C is the air volume of the exhaust path, and D is the air volume of the air conditioning supply path.

The outside air conditioner 12a takes in outside air and cleans it.
It is sent to the air conditioner 14a via the outside air supply path 12 and the air amount adjusting valve 13. The air conditioner 14a controls the air to have a constant temperature and a constant humidity (for example, 2
The temperature is adjusted to 4 ° C., 45%), and air is sent to the clean room 11 via the air conditioning supply path 14.

The air in the clean room 11 is exhausted by the fan 18a through the air amount adjusting valve 19 and the exhaust path 18.
A part of it is returned to the clean room 11 via the return path 15 and the air amount adjusting valve 16. While the impurity concentration in the clean room atmosphere is kept below a certain value, it is economical to reduce the exhaust gas amount and increase the return air amount.

However, when impurities are diffused into the atmosphere in the clean room 11, for example, in a semiconductor device manufacturing operation, in order to keep the concentration of impurities contained in the clean room atmosphere below a certain value, the amount of exhaust gas is increased and the air returned is returned. The amount of must be reduced.

First, the relationship between the impurity concentration of the clean room atmosphere and the impurity concentration of the condensed water is investigated in advance. Then, the upper limit of the impurity concentration of the condensed water is set in accordance with the upper limit of the impurity concentration of the clean room atmosphere.

The air in the clean room 11 during operation is sampled, dew condensation water is obtained by the analyzer 10 in the atmosphere described above, and the dew condensation water is analyzed. When the impurity concentration exceeds the upper limit value, the input / output converter 17 is operated to adjust the air amount adjusting valve 16 of the return path 15 and / or the air amount adjusting valve 13 of the outside air supply path 12 to adjust the air amount of the return path 15. The ratio (B / A) to the air volume of the outside air supply path 12 is lowered. In accordance therewith, the air amount adjusting valve 19 is adjusted to increase the air amount (C) in the exhaust path 18 so that the air pressure in the clean room 11 is kept in balance.

Specifically, the opening degree of the air amount adjusting valve 16 in the return path 15 is reduced and the opening degree of the air amount adjusting valve 19 in the exhaust path 18 is increased. At the same time, the opening degree of the air amount adjusting valve 13 of the outside air supply path 12 may be increased.

In this way, the contaminated clean room atmosphere is replaced with a clean atmosphere, and the impurity concentration in the clean room atmosphere is kept below a predetermined value. FIG. 3 is a diagram for explaining a clean room atmosphere control method (No. 2), the reference numerals are the same as those in FIG. 2, 21 is a main return path, 22 is an air amount adjusting valve, 23 is a return sub path,
24 is an impurity adsorbent, 25 is an air amount adjusting valve, and 26 is an input / output converter. Further, E represents the air volume of the return main route 21, and F represents the air volume of the return sub route 23.

In this example, in addition to the method shown in FIG.
A return sub-path 23 loaded with
The air amount adjusting valve 25 is provided in the. Impurity adsorbent 24
Is, for example, activated carbon.

The air in the clean room 11 during operation is sampled, dew condensation water is made by the analyzer 10 in the atmosphere described above, and the dew condensation water is analyzed. When the impurity concentration exceeds the upper limit,
The input / output converter 26 is operated to adjust the air amount adjusting valve 22 of the return main route 21 and the air amount adjusting valve 25 of the return sub route 23, and the ratio of the air volume of the return main route 21 to the air amount of the return sub route 23 ( Lower the E / F). Furthermore, this adjustment keeps the air pressure in the clean room 11 balanced.

Specifically, the opening degree of the air amount adjusting valve 22 in the return main path 21 is reduced, and the opening degree of the air amount adjusting valve 25 in the return sub path 23 is increased. By doing this, impurities in the air are removed in the return sub-path 23, and the concentration of impurities in the returned air is reduced. The contaminated clean room atmosphere is replaced with a clean atmosphere, and the impurity concentration in the clean room atmosphere is kept below a predetermined value.

[0037]

As described above, according to the present invention,
It is possible to continuously monitor the contamination status of the clean room. Further, the impurity concentration in the clean room can be suppressed to a predetermined value or less.

As a result, the influence of the clean room environment can be eliminated in the product manufacturing process, and a stable product yield can be secured. Further, since the ventilation process or the impurity adsorption process only needs to be performed when the impurity concentration in the clean room increases, the running cost of the air conditioning system can be reduced.

The present invention exerts a particularly great effect when applied to environmental control of a clean room used for manufacturing a semiconductor device.

[Brief description of drawings]

1 (a) and 1 (b) are views for explaining an atmosphere analyzer.

FIG. 2 is a diagram for explaining a clean room atmosphere control method (No. 1).

FIG. 3 is a diagram illustrating a clean room atmosphere control method (No. 2).

FIG. 4 is a diagram illustrating dew condensation from an atmosphere containing water.

[Explanation of symbols]

1 is the sampled air 2 is condensed water 3 is a cooling section, which is a cooling pipe 4a is a drain receiver 4b is a water ring trap 4c is the dew condensation water outlet 5 is a fan 6 is a filter 7 is an analyzer 8 is a computer 9 is a display 10 is an atmosphere analyzer 11 is a clean room 12 is the outside air supply route 12a is an external controller 13 is an air amount adjustment valve 14 is the air conditioning supply path 14a is an air conditioner 15 is the return route 16 is an air amount adjustment valve 17 is an input / output converter 18 is the exhaust path 18a is a fan 19 is an air amount adjustment valve 21 is the main return route 22 is an air amount adjustment valve 23 is the return sub route 24 is an impurity adsorbent 25 is an air amount adjustment valve 26 is an input / output converter A is the air volume of the outside air supply route B is the air volume of the return route C is the air volume in the exhaust path D is the air volume of the air conditioning supply path E is the air volume of the main return path F is the air volume of the return sub route

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A 61-223630 (JP, A) JP-A 3-99248 (JP, A) JP-A 2-173546 (JP, A) JP-A 54- 102191 (JP, A) JP 62-112940 (JP, A) JP 2-208433 (JP, A) JP 63-182548 (JP, A) JP 5-184350 (JP, A) JP-A-5-142109 (JP, A) JP-A-5-240753 (JP, A) JP-A-1-291142 (JP, A) Actually opened 64-37649 (JP, U) Actually opened 61-54286 (JP, U) Actual development Sho 62-123549 (JP, U) Patent 2586754 (JP, B2) Japanese Patent Publication No. 3-31486 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 1/00-1/44 F24F 7/06 F24F 11/02 H01L 21/02 JISST file (JOIS)

Claims (5)

(57) [Claims] 1. A method for analyzing an atmosphere, which comprises continuously collecting and cooling a room temperature atmosphere of a clean room, cooling the obtained condensed water, and analyzing impurities contained in the condensed water as needed. 2. A means for continuously continuously collecting a room temperature atmosphere in a clean room, a cooling unit for cooling the collected atmosphere, a drain receiver for collecting the condensed water produced in the cooling unit, and the condensed water. An atmosphere analyzer comprising: an analyzer for analyzing impurities. 3. The atmosphere analyzer according to claim 2, wherein the surfaces of the cooling unit and the drain receiver that come into contact with the condensed water are made of quartz or a polymer material. 4. The atmosphere analyzer according to claim 2, a first air amount adjusting valve provided in an outside air supply path for supplying outside air to the clean room, and air discharged from the clean room to the clean room. And a second air amount adjusting valve provided in the return path, and when the amount of impurities by the analyzer exceeds a preset amount, the first air amount adjusting valve reduces the ratio of the return path air amount to the outside air supply route air amount. 2 air amount adjusting valve or the first
And an input / output conversion unit for operating at least one of the air amount adjusting valves of 1 . 5. The atmosphere analyzer according to claim 2, a first air amount adjusting valve provided in a return main path for returning the air discharged from the clean room to the clean room, and one of the return main path. Second part provided in parallel with the part and provided in a return sub-path partially filled with an impurity adsorbent
And the first air amount adjusting valve and the first air amount adjusting valve for reducing the ratio of the return main path air volume to the return sub path air volume when the amount of impurities by the analyzer exceeds a preset amount. A control device for a clean room atmosphere, comprising: an input / output conversion unit that operates a second air amount adjusting valve.