JP2008080193A - Filtration system and filtration method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filtration system which accurately determines the filtration performance of a filtration filter and makes it possible to use the filtration filter to the limit of its performance. <P>SOLUTION: The filtration system is provided with; a filtration filter 11 which filtrates foreign substances in a chemical solution; a first-side passage 12 through which the chemical solution is introduced into the filtration filter 11; a first particle sensor 13 which monitors foreign substances in the chemical solution in the first-side passage 12; a secondary-side passage 14 through which the chemical solution filtrated by the filtration filter 11 is discharged; a second particle sensor 15 which monitors foreign substances in the chemical solution in the secondary-side passage 14; and a computation part 16 which computes a foreign substance-removal rate from the foreign substances detected by the first particle sensor 13 and the foreign substances detected by the second particle sensor 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a filtration system and a filtration method suitable for filtering a chemical solution in a semiconductor manufacturing process.

  In the substrate manufacturing process, a halogen chemical solution is used to clean the substrate. The halogen chemical solution after cleaning the substrate contains impurity particles. Therefore, a filtration filter is used to remove impurity particles from the halogenated chemical solution.

  FIG. 6 shows a filtration system 50 having a conventional filtration filter 51. In the filtration system 50, the water pressure before and after the filtration filter 51 is monitored by pressure gauges 52 and 53, and when these water pressures are opened beyond a specified pressure difference, it is determined that the filtration filter 51 is clogged.

  Based on this determination, the replacement time of the clogged filter 51 has been determined. Note that reference numeral 54 in FIG. 5 denotes a tank for accumulating chemicals or pure water to be filtered, and 55 denotes a pressurizing pump.

  However, in the conventional filtration system 50, as shown in FIG. 7, the pressure fluctuations of the pressure gauges 52 and 53 are large due to the pressure pulsation of the pressurization pump 55, and the accurate clogging timing of the filtration filter 51 is determined. It was difficult.

  Therefore, in practice, it is common to determine the replacement time of the filtration filter 51 based on the usage time of the filtration filter 51.

  As described above, in the conventional filtration system 50, the filtration filter 51 must be periodically replaced, and a reduction in the operation rate due to generation of replacement cost of the filtration filter 51 and stop of the equipment at the time of replacement occurs periodically. There was a problem.

  In addition, when a sudden failure occurs in the filtration membrane 51 of the filtration filter 51, when the pressure difference between the pressure gauges 52 and 52 is detected to be equal to or greater than the reference value, the impurities in the chemical solution are already secondary. Since it flows out to the side (downstream side), there has been a problem that the non-defective product rate of the product such as the substrate is lowered.

  Thus, since the conventional filtration system 50 cannot directly detect the membrane quality deterioration of the filtration membrane in the filtration filter 51, there is a problem that it cannot cope with a sudden failure.

  On the other hand, chemical filtration systems are widely used in semiconductor manufacturing equipment using halogenated chemicals, and there is a need for a technique that can detect degradation of the filtration filter in real time.

  This invention is made | formed in view of such a problem, and makes it a subject to provide the filtration system which can perform the lifetime prediction of a filtration filter correctly, and can be used to the limit of the performance of a filtration filter.

  The present invention employs the following means in order to solve the above problems.

That is, the present invention
A filter section;
A primary-side passage for introducing liquid into the filter unit;
A first foreign matter sensor for monitoring the number of foreign matters in the liquid in the primary passage;
A secondary passage for discharging the liquid filtered by the filter unit;
A second foreign matter sensor for monitoring the number of foreign matters in the liquid in the secondary passage;
An arithmetic unit for obtaining a removal rate of the foreign matter from the number of foreign matters detected by the first foreign matter sensor and the number of foreign matters detected by the second foreign matter sensor;
Is provided.

  In the present invention, the number of foreign matters in the liquid at the inlet (primary side passage) and outlet (secondary side passage) of the filter unit is directly detected, and the removal rate is obtained from the number of foreign matters. The life of the filter unit can be accurately determined without being affected.

  Here, it is preferable to provide a liquid introduction amount control device that controls an introduction amount of the liquid introduced into the filter unit when the removal rate does not reach a predetermined reference value.

  With this configuration, it is possible to suppress an increase in the number of foreign matters discharged from the filter unit even when the filtration performance of the filter unit is deteriorated.

  In addition, an alarm can be generated when the removal rate does not reach a predetermined reference value.

  With this configuration, it is possible to immediately recognize by a warning that the filtering performance of the filter unit has reached its limit, and therefore it is possible to take appropriate measures such as replacing the filter unit.

  Moreover, it can be set as the structure which has the flow volume monitoring means which monitors the flow volume of the said liquid in the said secondary side channel | path.

  With this configuration, it can be determined that the filter portion is clogged when the flow rate of the liquid in the secondary passage decreases.

The present invention also provides:
Filtering the foreign matter in the liquid with the filter part;
Introducing the liquid into the filter unit;
Discharging the liquid filtered by the filter unit;
Monitoring foreign matter in the liquid introduced into the filter unit;
Monitoring the foreign matter in the liquid discharged from the filter unit;
Obtaining a removal rate of the foreign matter from the foreign matter in the liquid introduced into the filter unit and the foreign matter in the liquid discharged from the filter unit;
including.

  In the present invention, the foreign matter contained in the liquid before and after the filter portion is detected without detecting the pressure before and after the filter portion, and the removal rate of the foreign matter is calculated from these front and rear foreign matters. Without being affected by this, it is possible to accurately determine the filtration characteristics in the filter section.

  According to the present invention, it is possible to accurately grasp the filtration performance of the filter unit without being affected by the pulsation of the pump or the like.

  Moreover, when the filtration performance of the filter unit reaches the limit, the filter unit can be quickly replaced by generating an alarm. Therefore, the filter part can be used up to the limit of the filtration performance, and the influence on the product due to the reduction of the filtration performance can be prevented.

  Hereinafter, a filtration system and a filtration method according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a filtration system 1 according to an embodiment of the present invention. The filtration system 1 is for filtering a chemical solution for semiconductor cleaning, for example.

  The filtration system 1 is a filter 11 that is a filter unit, a primary passage 12 that introduces a chemical into the filtration filter 11, and a first foreign matter sensor that monitors foreign matters in the chemical in the primary passage 12. A first particle sensor 13, a secondary side passage 14 that discharges the chemical liquid filtered by the filtration filter 11, and a second particle sensor that is a second foreign matter sensor that monitors foreign substances in the chemical solution in the secondary side passage 14 15, the foreign matter detected by the first particle sensor 13 and the foreign matter detected by the second particle sensor 15, a calculation unit 16 that calculates the removal rate of the foreign matter, and the amount of chemical introduced into the filtration filter 11 is controlled. And a control unit 18.

  1 is a pump driven by pressurized air, and 19 is a flow rate monitoring device for monitoring the flow rate of the chemical solution in the secondary side passage 14.

  Next, each of the above components will be described. The filtration filter 11 is for filtering a chemical solution through a filtration membrane, and a general filtration filter can be used. In the present embodiment, a plurality of filtration membranes of the filtration filter 11 are provided.

  For the primary side passage 12 and the secondary side passage 14, pipes having appropriate diameters are used. The first particle sensor 13 and the second particle sensor 15 are general liquid particle sensors, which irradiate the chemical liquid with light and detect scattered light caused by foreign substances (particles) in the chemical liquid, Detect foreign objects.

The calculation unit 16 can use a general personal computer or the like. The calculation unit 16 calculates the foreign substance removal rate K by the following equation.
K = (PC1-PC2) / PC1
K: Foreign matter removal rate (%)
PC1: Concentration of foreign matter detected by the first particle sensor 13
PC2: Concentration of the foreign matter detected by the second particle sensor 15

  The control unit 18 controls the pressure of the chemical solution discharged from the pump 17 by controlling the pump 17 based on the foreign substance removal rate K calculated by the calculation unit 16, and is introduced into the filtration filter 11. Control the pressure of chemicals.

  In addition, the control unit 18 generates an alarm (warning) when the foreign substance removal rate K calculated by the calculation unit 16 does not reach a predetermined reference value.

Next, the operation of the filtration system 1 will be described. Here, the case where the chemical solution used in the semiconductor cleaning apparatus is stored in the chemical solution storage tank and the chemical solution in the chemical solution storage tank is filtered by the filtration system 1 will be described. The semiconductor is cleaned by being immersed in a chemical solution in the chemical solution storage tank.

  In this case, the chemical solution in the chemical solution tank is introduced into the filtration filter 11 through the pump 17 and the primary side passage 12.

  The chemical liquid filtered by the filtration filter 11 is returned to the chemical liquid storage tank via the secondary side passage 14. In this way, the chemical solution is circulated and filtered.

  The amount of foreign matter in the chemical solution in the primary side passage 12 and the secondary side passage 14 is detected by the first particle sensor 13 and the second particle sensor 15, respectively.

  The amount of foreign matter detected by the first and second particle sensors 13 and 15 is input to the calculation unit 16, where the foreign matter removal rate K is calculated by Equation 1 described later. The calculated foreign substance removal rate K is input to the control unit 18.

  The control unit 18 compares the foreign matter removal rate K with a predetermined reference value, and controls the driving pressure of the pump 17 and generates an alarm when the removal rate K is less than the predetermined reference value.

  By controlling the driving pressure of the pump 17, the chemical discharge pressure of the pump 17 can be reduced. Thereby, the pressure of the chemical | medical solution introduce | transduced into the filtration filter 11 reduces, and the foreign material amount discharged | emitted from the filtration filter 11 also reduces.

  Next, the control method in the case of filtering the chemical | medical solution used with a semiconductor cleaning apparatus with the filtration system 1 as an example is demonstrated.

  Here, the step of filtering foreign substances in the chemical solution with the filtration filter 11, the step of introducing the chemical solution into the filtration filter 11, the step of discharging the chemical solution filtered with the filtration filter 11, and the chemical solution introduced into the filtration filter 11 A step of monitoring foreign matter in the inside, a step of monitoring foreign matter in the chemical solution discharged from the filtration filter 11, a foreign matter in the chemical solution introduced into the filtration filter 11, and a foreign matter in the chemical solution discharged from the filtration filter 11 And a step of obtaining a foreign substance removal rate.

  In the present embodiment, as shown in FIG. 2, the filtration system 1 is connected to a chemical storage tank 31 that stores the chemical 30. The semiconductor 32 is cleaned by being immersed in the chemical solution 30 in the chemical solution storage tank 31.

  FIG. 3 shows the relationship between the filtration time and the number of foreign matters in the primary side passage 12 and the secondary side passage 14 when the filtration performance suddenly decreases when the filtration performance of the filtration filter 11 is in the normal range. Show.

  Reference numeral 20 in FIG. 3 indicates the relationship between the filtration time and the number of foreign matters in the primary passage 12, and 21 indicates the relationship between the filtration time and the number of foreign matters in the secondary passage 14.

  In a range where the filtration performance of the filtration filter 11 is normal, the number of foreign matters contained in the chemical solution in the primary side passage 12 and the secondary side passage 14 decreases as the filtration time by the filtration filter 11 becomes longer. In the filtration filter 11, the accumulated amount of foreign matters increases as the filtration time elapses. Further, the removal rate K is substantially constant regardless of the elapse of the filtration time.

Here, when foreign matter accumulated in the filtration filter 11 increases to some extent, the primary-side passage 1
The pressure of the chemical solution in 2 is increased, the hole in the filtration membrane of the filtration filter 11 is enlarged, and the foreign matter accumulated in the filtration filter 11 is discharged to the secondary side passage 14.

  Thereby, as shown by the protruding portion 21a of the curve 21, the number of foreign substances contained in the chemical solution in the secondary side passage 14 increases rapidly. In this case, the removal rate K becomes small.

  When the foreign matter accumulated in the filtration filter 11 is discharged to the secondary passage 14, the filtration performance of the filtration filter 11 returns to normal thereafter. Therefore, the removal rate K after the protruding portion 21a is generated returns to a normal value.

  In this way, while the chemical solution is being filtered, the removal rate K is periodically calculated, and the state change of the removal rate K is monitored. Then, when the removal rate K temporarily increases to become less than a predetermined reference value and becomes equal to or higher than the predetermined reference value after a short time, the foreign matter accumulated in the filtration filter 11 is discharged. It can be judged.

  In the unlikely event that the filtration filter 11 is clogged and the filtration filter 11 is blocked, the flow rate monitoring device 19 detects a decrease in the flow rate in the secondary passage 14 and an alarm is generated from the control unit 18. Thereby, since abnormality of the filtration filter 11 can be judged immediately, appropriate measures, such as replacing | exchanging the filtration filter 11, can be performed.

  FIG. 4 shows the relationship between the filtration time when the filtration performance of the filtration filter 11 gradually decreases and approaches the end of life, and the number of foreign substances in the primary side passage 12 and the secondary side passage 14.

  A curve 22 in FIG. 4 shows the relationship between the filtration time and the number of foreign matters in the primary side passage 12, and a curve 23 shows the relationship between the filtration time and the number of foreign matters in the secondary side passage 14.

  In general, in the filter, “increase in pressure loss” and “decrease in removed particle performance” occur as the use time of the filter membrane elapses.

  For this reason, the number of foreign substances in the secondary side passage 14 gradually increases as the filtration time elapses. In the present invention, the removal rate K is periodically calculated, and when the removal rate K becomes less than a predetermined reference value for a predetermined time or more, control is performed so as to lower the driving pressure of the pump 17.

  That is, as shown in FIG. 5, when the foreign matter removal rate K decreases from A to B and this state continues for a long time, it is determined that the performance of the filtration membrane is greatly reduced (for example, when the lifetime of the filtration membrane is detected). Then, the driving pressure of the pump 17 is lowered in real time to reduce the delivery pressure of the chemical liquid introduced into the filtration filter 11.

  By performing such control, the pressure of the chemical solution delivered from the pump 17 decreases, and the pressure (load) applied to the filtration membrane of the filtration filter 11 is reduced. As a result, the number of foreign matters that pass through the filtration membrane of the filtration filter 11 and are discharged to the secondary passage 14 can be reduced.

  Thereby, even when the lifetime of the filtration filter 11 comes, the foreign material outflow to the secondary side channel | path 14 can be suppressed. Therefore, it is possible to prevent the semiconductor from being poorly cleaned.

  Further, at the time when the driving pressure of the pump 17 is controlled to decrease, an alarm (warning) indicating that the life of the filter membrane in the filter 11 has come is generated.

This warning can immediately recognize that the filter filter 11 has reached the end of its life, so that appropriate measures such as replacing the filter 11 can be taken. Further, the filtration filter 11 can be used with confidence up to the limit of the filtration performance.

  Thus, in the filtration system 1 of the present invention, the first particle sensor 13 detects the amount of foreign matter in the chemical solution in the primary passage 12 of the filtration filter 11 and the second particle sensor 15 uses the chemical solution in the secondary passage 14. The amount of foreign matter in the filter is detected and the removal rate K of the foreign matter of the filtration filter 11 is calculated from the amount of foreign matter. Therefore, the filtration ability of the filtration filter 11 in the filtration membrane can be accurately detected.

  Conventionally, it has been common to use a bellows pump accompanied by pressure fluctuations (pulsations) when performing chemical circulation filtration of a semiconductor cleaning device. Since this bellows pump does not show a stable pressure transition, it has been difficult to detect the pressure loss value of the filtration filter with the conventional technique.

  On the other hand, since the filtration system 1 of the present invention detects the filtration performance of the filtration filter 11 without detecting the pressure before and after the filtration filter 11, even when a bellows pump is used as the pump 17, for example, pulsation Without being influenced by the above, it is possible to stably perform the performance monitoring and life prediction of the filtration membrane in the filtration filter 11.

  Furthermore, when the filtration filter 11 approaches the end of its life and the filtration capacity is lower than the standard, the pressure of the chemical solution introduced into the filtration filter 11 is controlled by the control unit 18 in synchronization with detection of a foreign substance in the chemical solution. . Accordingly, since the amount of foreign matter discharged from the filtration filter 11 to the secondary passage 14 can be reduced, it is possible to compensate for the reduction in the foreign matter removal capability of the filtration filter 11.

  Moreover, since the filter 11 can be used to the end of its service life, it is not necessary to replace it regularly before the service life. Therefore, the replacement cost of the filtration filter 11 can be reduced, and a decrease in the equipment operation rate for each replacement can be prevented.

  Furthermore, even when a filtration membrane abnormality of the filtration filter 11 suddenly occurs, it is possible to minimize a decrease in the rate of non-defective products such as semiconductors. Moreover, since the lifetime of the filter 11 can be extended, the amount of filtration membrane discarded can be reduced, and the effect of reducing industrial waste can be obtained.

  In addition, although the said embodiment demonstrated the case where the chemical | medical solution used at a semiconductor washing | cleaning process was filtered, this invention is applicable when filtering various liquids, such as various chemical | medical solutions and pure water.

It is a figure which shows the filtration system which concerns on this invention. It is a figure which shows the system | strain at the time of applying the filtration system which concerns on this invention to a semiconductor cleaning apparatus. It is a figure which shows the relationship between the filtration time when the discharge | emission amount of a foreign material increases suddenly when the filtration performance of the filtration filter which concerns on this invention is normal, and the number of foreign materials in a primary side channel | path and a secondary side channel | path. . It is a figure which shows the relationship between the filtration time when the filtration performance of the filtration filter which concerns on this invention is nearing a lifetime, and the number of the foreign materials in a primary side channel | path and a secondary side channel | path. It is a figure explaining the method of controlling the drive pressure of the pump which concerns on this invention. It is a figure which shows the filtration system which concerns on a prior art example. It is a figure which shows the pressure before and behind the filtration filter of the filtration system which concerns on a prior art example.

Explanation of symbols

1 Filtration system 11 Filtration filter (filter part)
12 Primary side passage 13 First particle sensor (first foreign matter sensor)
14 Secondary side passage 15 Second particle sensor (second foreign matter sensor)
DESCRIPTION OF SYMBOLS 16 Calculation part 17 Pump 18 Control part 19 Flow monitoring apparatus 30 Chemical solution 31 Chemical solution storage tank 32 Semiconductor 50 Filtration system 51 Filtration filter 52,53 Pressure gauge 54 Tank 55 Pressure pump

Claims (5)

A filter unit for filtering foreign matter in the liquid;
A primary passage for introducing the liquid into the filter portion;
A first foreign matter sensor for monitoring foreign matter in the liquid in the primary passage;
A secondary passage for discharging the liquid filtered by the filter unit;
A second foreign matter sensor for monitoring the foreign matter in the liquid in the secondary passage;
A calculation unit for obtaining a removal rate of the foreign matter from the foreign matter detected by the first foreign matter sensor and the foreign matter detected by the second foreign matter sensor;
A filtration system comprising:   The filtration system according to claim 1, further comprising a liquid introduction amount control device that controls an introduction amount of the liquid introduced into the filter unit when the removal rate does not reach a predetermined reference value.   The filtration system according to claim 1 or 2, wherein an alarm is generated when the removal rate does not reach a predetermined reference value.   The filtration system according to claim 1, further comprising a flow rate monitoring unit that monitors the flow rate of the liquid in the secondary side passage. Filtering the foreign matter in the liquid with the filter part;
Introducing the liquid into the filter unit;
Discharging the liquid filtered by the filter unit;
Monitoring foreign matter in the liquid introduced into the filter unit;
Monitoring the foreign matter in the liquid discharged from the filter unit;
Obtaining a removal rate of the foreign matter from the foreign matter in the liquid introduced into the filter unit and the foreign matter in the liquid discharged from the filter unit;
A filtration method comprising:

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