JP5042166B2 - Conductivity measuring device and conductivity measuring method using conductivity measuring device - Google Patents

Description

  The present invention relates to a conductivity measuring device for measuring the conductivity of a fluid to be measured such as a chemical solution used for cleaning a silicon wafer, for example, during the manufacture of a semiconductor such as a silicon wafer, and a conductivity using the conductivity measuring device. It relates to a rate measuring method.

  Conventionally, for example, in a semiconductor manufacturing process, a cleaning process is performed to remove impurities, oxides, and the like attached to the surface of a silicon wafer. By sufficiently removing impurities, oxides and the like in this cleaning process, the electronic circuit can be accurately patterned in the patterning process.

  For this reason, in the cleaning process, for example, hydrofluoric acid, nitric acid, hydrochloric acid, phosphoric acid, hydrofluoric nitric acid, sulfuric acid, ammonia, etc. are used as chemicals to remove impurities and oxides attached to the surface of the silicon wafer.

It should be noted that the chemical solution used in the cleaning process requires management of the concentration of the chemical solution because the ability to remove oxides and the like greatly varies depending on the concentration of the chemical solution.
Thus, when managing the density | concentration of a chemical | medical solution, the measuring apparatus which measures the density | concentration of a chemical | medical solution is used.

  In such a measuring apparatus, two pairs of electrodes are arranged in a piping path so as to be in contact with a fluid to be measured flowing in the piping path, and a voltage is applied between the electrodes to obtain a current value. The conductivity of the fluid to be measured is calculated from the relationship between the current values, and the concentration of the fluid to be measured is calculated from this conductivity (for example, Patent Document 1).

  In addition, in the measuring apparatus having two pairs of electrodes, an AC constant current is passed from a constant current AC power source to a pair of electrodes located outside, and the voltage between the other pair of electrodes located inside is set to a high input impedance. Since the measurement is performed with an AC voltmeter, there is an advantage that the measurement accuracy is low because of being hardly influenced by polarization.

  However, when such a measuring device is installed in the piping path, it is affected by the piping other than between the electrodes in the entire piping path, resulting in an error in the impedance value between the electrodes. A smaller value may be output.

  For this reason, conventionally, as shown in FIG. 8, the electrode 102 of the measuring device 100 is installed in a direction perpendicular to the piping path filled with the fluid to be measured, so that almost no current flows through the external piping 104. As shown in FIG. 9, the entire electrode 202 of the measuring apparatus 200 is covered with a cover (insulator) 206 and guarded so that no current flows through the external pipe 204. Things were used.

In this way, if the structure does not allow the current to flow through the external piping, there is no error in the impedance value between the electrodes, so that it is not necessary to correct this impedance value.
JP 2007-327950 A

By the way, in particular, the error that occurs in the impedance value between the electrodes becomes larger as the piping length of the portion other than between the electrodes is shorter. Therefore, the total length of the piping path is longer than the length between the electrodes. However, if the length of the entire piping path is relatively short, the error that occurs in the impedance value between the electrodes becomes large. It was happening.

Furthermore, if the entire electrode is covered with a cover (insulator), there may be a problem that it cannot be installed due to the inner diameter of the piping path.
In view of such a current situation, the present invention can accurately calculate the conductivity of the fluid to be measured flowing in the piping path even if the length and material of the piping path differ depending on the measurement environment. It is another object of the present invention to provide a conductivity measuring device that can be reliably installed and a conductivity measuring method using the conductivity measuring device.

The present invention was invented in order to achieve the problems and objects in the prior art as described above,
The conductivity measuring device of the present invention is
An electrode is arranged at a predetermined position of the main flow path of the piping path so as to be in contact with the fluid to be measured flowing through the piping path, and the impedance value between the electrodes is calculated from the current flowing between the electrodes and the voltage between the electrodes. A conductivity measuring device that measures and calculates the conductivity of a fluid to be measured based on this impedance value,
The conductivity measuring device is:
At least a pair of electrodes arranged in a measurement part of the main flow path of the piping path;
A conductivity sensor that applies an alternating voltage between the electrodes and measures a current value flowing between the electrodes;
By obtaining an impedance value of a path portion made of non-conductive piping out of the entire piping path based on a current value flowing between the electrodes measured by the conductivity sensor, and performing predetermined arithmetic processing on this impedance value A calculation unit for calculating conductivity of the fluid to be measured;
Having at least
In the calculation unit,
The ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. Calculate
Impedance value of the entire piping path;
From the ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. , Calculating only the impedance value between the electrodes,
The electrical conductivity of the fluid to be measured is calculated based on the impedance value.

In addition, the conductivity measuring method of the present invention is
An electrode is arranged at a predetermined position of the main flow path of the piping path so as to be in contact with the fluid to be measured flowing through the piping path, and the impedance value between the electrodes is calculated from the current flowing between the electrodes and the voltage between the electrodes. A conductivity measurement method for measuring and calculating the conductivity of a fluid to be measured based on this impedance value,
The conductivity measuring method is:
Disposing at least a pair of electrodes in the measurement part of the main flow path of the piping path;
Applying an alternating voltage between the arranged electrodes through a conductivity sensor to measure a current value flowing between the electrodes;
Based on the value of the current flowing between the electrodes measured by the conductivity sensor, the calculation unit obtains an impedance value of a path portion made of a non-conductive pipe in the entire pipe path, and performs a predetermined calculation process on this impedance value. Calculating the conductivity of the fluid to be measured by applying
Having at least
In the step of calculating the conductivity of the fluid to be measured,
The ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. Calculate
Impedance value of the entire piping path;
From the ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. , Calculating only the impedance value between the electrodes,
The conductivity of the fluid to be measured is calculated based on this impedance value.

  Thus, in the calculation unit, a length obtained by subtracting the length between the electrodes from the length (l) between the electrodes arranged in the measurement unit and the length of the path portion made of the nonconductive pipe in the entire piping path corresponding thereto. If only the impedance value between the electrodes is calculated from the ratio with the length (L) and the impedance value of the entire piping route, and the conductivity of the fluid to be measured is calculated based on this impedance value, the piping When the electrodes are arranged in the main flow path of the path, the conductivity of the fluid to be measured can be calculated with high accuracy.

The conductivity measuring device of the present invention is
An electrode is arranged at a predetermined position of a sub-flow path formed by branching separately from the main flow path of the piping path so as to come into contact with the fluid to be measured flowing through the piping path, and a voltage is applied between the electrodes to flow. A conductivity measuring device that measures an impedance value between electrodes from a current and a voltage between electrodes, and calculates the conductivity of a fluid to be measured based on the impedance value,
The conductivity measuring device is:
At least a pair of electrodes arranged in a measurement part of a sub-flow path of the piping path;
A conductivity sensor for applying an alternating voltage to the electrodes and measuring a current value flowing between the electrodes;
Calculation that obtains the impedance value of the entire piping path based on the current value flowing between the electrodes measured by the conductivity sensor, and calculates the conductivity of the fluid to be measured by applying a predetermined arithmetic process to the impedance value And
Having at least
In the calculation unit,
A ratio of a length (T) obtained by adding a length obtained by subtracting the inter-electrode length from the entire length of the sub-channel to the inter-electrode length (t) of the sub-channel and the length of the entire main channel is calculated. And
The impedance value of the connecting pipe line to which both ends of the sub-flow path are connected in the sub-flow path and the main flow path,
From the ratio of the length obtained by subtracting the length between the electrodes from the total length of the sub-channel to the length between the electrodes of the sub-channel (t) and the length of the entire main channel (T), Calculate only the impedance value between the electrodes,
The electrical conductivity of the fluid to be measured is calculated based on the impedance value.

In addition, the conductivity measuring method of the present invention is
An electrode is arranged at a predetermined position of a sub-flow path formed by branching separately from the main flow path of the piping path so as to come into contact with the fluid to be measured flowing through the piping path, and a voltage is applied between the electrodes to flow. An electrical conductivity measurement method for measuring an impedance value between electrodes from a voltage between an electric current and an electrode, and calculating an electrical conductivity of a fluid to be measured based on the impedance value,
The conductivity measuring method is:
Arranging at least a pair of electrodes in the measurement part of the sub-flow path of the piping path;
Applying an alternating voltage between the arranged electrodes through a conductivity sensor to measure a current value flowing between the electrodes;
Based on the value of the current flowing between the electrodes measured by the conductivity sensor, the calculation unit obtains the impedance value of the entire piping path, and performs a predetermined calculation process on the impedance value to thereby determine the conductivity of the fluid to be measured. Calculating
Having at least
In the step of calculating the conductivity of the fluid to be measured,
A ratio of a length (T) obtained by adding a length obtained by subtracting the inter-electrode length from the entire length of the sub-channel to the inter-electrode length (t) of the sub-channel and the length of the entire main channel is calculated. And
Impedance value of the entire piping path;
From the ratio of the length obtained by subtracting the length between the electrodes from the total length of the sub-channel to the length between the electrodes of the sub-channel (t) and the length of the entire main channel (T), Calculate only the impedance value between the electrodes,
The conductivity of the fluid to be measured is calculated based on this impedance value.

  Thus, in the calculation unit, a length obtained by adding a length obtained by subtracting the inter-electrode length from the entire length of the sub-channel to the inter-electrode length (t) of the sub-channel and the length of the entire main channel ( If only the impedance value between the electrodes is calculated from the ratio of T) and the impedance value of the entire piping path, and the conductivity of the fluid to be measured is calculated based on this impedance value, in particular, the main flow path of the piping path In addition, when the electrode is arranged in a sub-flow channel formed by partially branching, the conductivity of the fluid to be measured can be calculated with high accuracy.

Further, the conductivity measuring device and the conductivity measuring method of the present invention are:
An output unit that outputs the conductivity calculated by the calculation unit is provided.
In addition, the conductivity measuring method of the present invention is
The method includes a step of outputting the conductivity calculated in the step of calculating the conductivity at an output unit.

When the conductivity calculated in this way is output by the output unit, the measurer can actually visually recognize the fluid, so that the fluid to be measured can be managed well.
Further, the conductivity measuring device and the conductivity measuring method of the present invention are:
The electrode is horizontally provided along the flow direction of the piping path.

  In this way, if the electrodes are installed horizontally so as to follow the flow direction of the piping path, the electrodes can be installed in a wider range compared to the case where the electrodes are arranged perpendicular to the flow direction. It is possible to prevent problems that are difficult to obtain.

  Furthermore, if the electrodes are arranged horizontally so as to be along the flow direction of the piping path, the electrodes will not block the flow of the fluid to be measured as in the case where the electrodes are arranged perpendicular to the flow direction, and turbulent flow will not occur. Measurement can always be performed with high accuracy.

Further, the conductivity measuring device and the conductivity measuring method of the present invention are:
The number of the electrodes is either one pair or two pairs.
In particular, if two pairs of electrodes are used, even if bubbles occur in the measured fluid at the electrode interface, the measurement is not affected and the impedance value does not fluctuate, and the conductivity of the measured fluid is accurately measured. It can be calculated well.

Further, the conductivity measuring device and the conductivity measuring method of the present invention are:
The fluid to be measured is a chemical solution for removing impurities and oxides adhering to the surface of the silicon wafer and is a fluid having conductivity.

As described above, when the fluid to be measured is a chemical solution and a fluid having conductivity, the present conductivity measuring device and the conductivity measuring method can be used particularly in the manufacturing process of the silicon wafer.
For this reason, when manufacturing a silicon wafer, if this conductivity measuring apparatus and conductivity measuring method are used, it can be used for obtaining a high quality silicon wafer.

Further, the conductivity measuring device and the conductivity measuring method of the present invention are:
The calculation unit
It has a function of calculating the concentration of the fluid to be measured based on the calculated conductivity of the fluid to be measured.

  As described above, if the calculation unit has a function of calculating the concentration based on the conductivity of the fluid to be measured, the concentration of the chemical solution that is an important fluid to be measured is always managed, particularly when manufacturing a silicon wafer. Therefore, the conductivity measuring device and the conductivity measuring method can be suitably applied when manufacturing a silicon wafer.

  According to the present invention, the conductivity of the fluid to be measured flowing in the piping path can be accurately calculated even if the length and material of the piping path differ depending on the measurement environment, and the piping path can be reliably installed in any piping path. A possible conductivity measuring device and a conductivity measuring method using the conductivity measuring device can be provided.

Hereinafter, embodiments of the present invention will be described in more detail based on the drawings.
FIG. 1 is an explanatory diagram for explaining a use state of a conductivity measuring device according to a first embodiment of the present invention, FIG. 2 is an enlarged view of the conductivity measuring device shown in FIG. 1, and FIG. 3 is a conductivity of the present invention. FIG. 4 is a schematic diagram for explaining numerical positions used when calculating the conductivity of the fluid to be measured by the calculation unit of the conductivity measuring device shown in FIG.

  The conductivity measuring apparatus and the conductivity measuring method of the present invention are for measuring the conductivity of a fluid to be measured such as a chemical solution used for cleaning a silicon wafer, for example, when manufacturing a semiconductor such as a silicon wafer.

Hereinafter, the conductivity measuring device and the conductivity measuring method in the examples of the present invention will be described.
As shown in FIG. 1 and FIG. 2, the conductivity measuring device 10 of the present invention has electrodes 22 a to 22 on the measuring section 20 of the main flow path 18 of the piping path 12 so as to come into contact with the fluid 14 to be measured flowing through the piping path 12. The impedance value between the electrode 22c and the electrode 22d is measured from the current flowing by applying an alternating voltage between the electrode 22a and the electrode 22b and the voltage between the electrode 22c and the electrode 22d. Based on this impedance value, the conductivity of the fluid 14 to be measured flowing through the piping path 12 is calculated.

  Any fluid can be used as the fluid 14 to be measured as long as it is a fluid having conductivity (including a mixed solution). However, when the conductivity measuring device is used for cleaning a silicon wafer, hydrofluoric acid, nitric acid is used. Chemicals such as hydrochloric acid, phosphoric acid, hydrofluoric acid, sulfuric acid, and ammonia are the measurement targets.

In addition, in the conductivity measuring apparatus 10 and the conductivity measuring method using the electrodes 22a to 22d of the present invention, a so-called two-electrode method or four-electrode method using electrodes in pairs can be used. In the present embodiment shown in FIG. 4, a four-electrode method using two pairs of electrodes is used.

  This four-electrode method is a conventionally known technique. For example, Patent Document 1 also describes the technical contents, but in brief, four electrodes are arranged side by side so as to contact the fluid to be measured. Of these electrodes, an AC voltage is applied between the electrodes 22a and 22b located on the outer side, and the impedance value of the fluid to be measured is obtained from the flowing current and the voltage between the inner electrode 22c and the electrode 22d. Is.

  Specifically, such a conductivity measuring device 10 is configured to apply an alternating voltage between two pairs of electrodes arranged in the measurement unit 20 of the main flow path 18 of the piping path 12 and the electrodes 22a and 22b. Conductivity sensor 24 that measures the current value between 22a and electrode 22b and the voltage value between electrode 22c and electrode 22d, and piping path 12 based on the voltage value between electrode 22c and electrode 22d measured by conductivity sensor 24. A calculation unit 26 that obtains the impedance value of the pipe path 12 portion made of a nonconductor among the whole and calculates the conductivity of the fluid 14 to be measured by performing a predetermined calculation process on the impedance value, at least. ing.

  The “pipe path 12 portion made of a non-conductor in the entire pipe path 12” means that when the material of the pipe path 12 is all a conductor (for example, SUS) except for the measurement unit 20, all the non-conductors (for example, PTFE) are used. ) Is a piping path portion in the three cases where conductors and non-conductors are mixed.

In the present embodiment shown in FIGS. 1 and 2, the material of the piping path 12 is assumed to be non-conductive.
Moreover, the piping material of the measurement part 20 in which the electrical conductivity measuring apparatus provided in the middle of the piping path | route is a nonconductor (for example, PTFE).

  Further, in the conductivity measuring apparatus 10 in the present embodiment, the output unit 28 and the calculating unit 26 are disposed in the controller 30 as shown in FIGS. 1 and 3, and the controller 30 is separated from the apparatus main body 21. Is provided.

  In addition to the output unit 28 that outputs the conductivity of the fluid 14 to be measured, such a controller 30 may be provided with a temperature display unit 31 that displays the temperature, and functions can be added as appropriate. is there.

  In the piping path 12 in the present embodiment in which such a conductivity measuring device 10 is installed, the fluid 14 to be measured is stored in the tank 16 in advance, and the fluid 14 to be measured in the tank 16 is arrowed via the pump 34. It is made to flow in the direction of the conductivity measuring device 10 which is the direction of

  Then, the fluid 14 to be measured flowed by the pump 34 is sent to the heat exchanger 32 after passing through the conductivity measuring device 10 and is returned to the tank 16 again, forming a series of cycles.

  By the way, in the conductivity measuring apparatus 10 of the present invention as described above, the following calculation processing is performed particularly in the calculation unit 26 described above, and various numerical values used in the calculation processing are shown in FIG. This will be described with reference to the schematic diagram of the piping route.

  In the calculation unit 26 according to the present invention, as shown in FIG. 4, first, the length (l) between the electrodes 22 a and 22 b arranged in the measurement unit 20 and non-conductive piping in the entire piping path 12 are formed. A length (L) obtained by subtracting the length between the electrodes 22a to 22b from the length of the path portion is input.

  In the present embodiment, as described above, all the materials of the piping path 12 are assumed to be non-conductors, so the length (L) is the length between the electrodes 22a and 22b from the entire length of the piping path 12. The distance obtained by subtracting (l).

If the material of the piping path 12 is all a conductor other than the measurement unit 20, the length (L) is only the non-conductor portions N1 and N2 which are portions other than between the electrodes 22a and 22b of the measurement unit 20. It becomes.

  In other words, the length (L) in this case is obtained by subtracting the length (l) between the electrodes 22a and 22b and the length (M) of the piping path other than the measurement unit 20 from the entire length of the piping path 12. The distance, that is, the distance obtained by adding only the non-conductor portion (N1) and the non-conductor portion (N2).

  Furthermore, when the piping path 12 is a mixture of conductors and non-conductors, the length (l) between the electrodes 22a and 22b and the length of the conductor portion are subtracted from the entire length of the piping path 12. The remaining distance is the length (L).

Next, the ratio of the length (L) of the entire piping path 12 to the length (l) between the electrodes 22a and 22b arranged in the measurement unit 20 is calculated.
Assuming that the ratio of l to L is l: L = 1: a, the following formula (1) is obtained.

Further, the ratio of the length of l: L described above is calculated based on the impedance value (Z) between the electrode 22a and the electrode 22b and the length of the pipe path 12 portion made of a nonconductor in the entire pipe path 12. Since it is the same as the ratio of the impedance value (Z1) of the part of the length (L) minus the length (l) between 22b,
The relationship of l: L = Z: Z1 = 1: a is obtained, and the following mathematical formula (2) is obtained.

This relationship is established when the inner diameter (r) of the piping path 12 and the inner diameter (R) of the measuring section 20 are the same size. In this embodiment shown in FIG. 1 or FIG. The inner diameter (r) of the path 12 and the inner diameter (R) of the measurement unit 20 have the same size.

  When the inner diameter (r) of the piping path 12 and the inner diameter (R) of the measuring unit 20 are different, the inner diameter (r) of the piping path 12 is measured in consideration of the cross-sectional area ratio of each inner diameter. After conversion to be the same as the inner diameter (R) of the part 20, from the entire piping path 12 with respect to the length (l) between the electrodes 22a to 22b arranged in the measurement part 20 as shown in the above formula (1). What is necessary is just to obtain | require the ratio of the length (L) which pulled the length (l) between the electrode 22a and the electrode 22b.

Here, when the inner diameter (r) of the piping path 12 is different from the inner diameter (R) of the measuring section 20, the inner diameter (r) of the piping path 12 is converted to be the same size as the inner diameter (R) of the measuring section 20. The length of the virtual piping path 12 is calculated by the following mathematical formula (3).

The impedance value (Z0) of the fluid 14 to be measured between the electrodes can be obtained from the AC voltage between the electrodes actually measured by the conductivity sensor 24 and the current value flowing between the electrodes. The impedance value (Z0) of the fluid 14 to be measured between the electrodes is obtained by subtracting the impedance value (Z) between the electrodes 22a and 22b and the length (l) between the electrodes 22a and 22b from the entire piping path 12. The impedance value (Z1) of this part is synthesized.

  The relationship between Z0, Z, and Z1 is as shown in the following formula (4), which is the formula for the combined resistance.

Substituting Equation (2) into Equation (4) above yields Equation (5) below.

In the calculation unit 26, an impedance value obtained from the current flowing between the electrodes 22a and 22b and the voltage between the electrodes 22c and 22d is obtained.

  To this impedance value

The value multiplied by is the true value.
Therefore, for example, if the length (l) between the electrodes 22a and 22b arranged in the measuring unit 20 is 100 mm, the entire length (L) of the piping path 12 is 2000 mm, and the entire piping path 12 is made of a non-conductor, l and Applying L to equation (1)

Is calculated.
And if this constant a = 20 is substituted into the above equation (5),

It becomes.
Therefore, the impedance value (Z) between the electrodes 22a and 22b is 1.05 times the impedance value (Z0) of the fluid to be measured between the electrodes, which is obtained from the AC voltage between the electrodes and the current flowing between the electrodes. It is obtained by doing. When obtaining the impedance value between the electrode 22c and the electrode 22d, it may be multiplied by 1.05.

  That is, if the impedance value of the fluid to be measured between the electrodes obtained from the AC voltage between the electrodes 22c and 22d and the current flowing between the electrodes 22a and 22b is, for example, 100Ω, the electrodes 22c and the electrodes The impedance value (Zcd) between 22d is expressed by the following equation (5).

It becomes.
Then, the electrical conductivity of the fluid to be measured is calculated by multiplying the impedance value (Zcd) between the electrode 22c and the electrode 22d by a predetermined coefficient, and the electrical conductivity of the fluid to be measured is output to the output unit of the controller 30. By being output to 28, the measurer can visually recognize it.

  If the above-described calculation unit 26 stores in advance a relational expression between the conductivity and concentration of a known fluid 14 to be measured, the concentration of the fluid 14 to be measured is calculated from the calculated conductivity of the fluid 14 to be measured. Can be calculated.

  In addition, in the output unit 28, not only the conductivity of the fluid 14 to be measured but also the resistivity and the concentration that are the reciprocal of the conductivity can be displayed. That is.

  Further, the controller 30 may be provided with a temperature display unit 31 for displaying the temperature of the fluid 14 to be measured in addition to the conductivity and concentration of the fluid 14 to be measured. In this case, a temperature sensor is separately provided. Can fulfill the function. As described above, functions to be added in addition to the conductivity and concentration of the fluid 14 to be measured can be appropriately added depending on the use environment.

  As described above, the conductivity measuring device and the conductivity measuring method according to the first embodiment can accurately measure the conductivity and concentration of the fluid to be measured by performing the arithmetic processing as described above in the calculation unit. Is.

Next, a conductivity measuring device and a conductivity measuring method according to Example 2 of the present invention will be described.
FIG. 5 is an explanatory diagram for explaining a use state of the conductivity measuring device according to the second embodiment of the present invention, FIG. 6 is an enlarged view of the conductivity measuring device shown in FIG. 5, and FIG. 7 is a diagram showing the conductivity shown in FIG. It is the schematic for demonstrating the numerical location used when calculating the electrical conductivity of the fluid to be measured by the calculation part of a rate measuring device.

Note that the difference between the second embodiment and the first embodiment is that, in the second embodiment, the electrodes are arranged in a sub-flow channel provided separately from the main flow channel.
As shown in FIGS. 5 and 6, the conductivity measuring device 10 according to the second embodiment of the present invention is partly separate from the main flow path 18 of the piping path 12 so as to be in contact with the fluid 14 to be measured flowing through the piping path 12. The electrodes 22a to 22d are arranged at predetermined positions of the sub-flow path 36 formed in a branched manner, and among these electrodes, an AC voltage is applied between the electrodes 22a and 22b, and an electrode 22a is determined from a current flowing between the electrodes 22a and 22b. And the electrode 22b are measured, and the conductivity of the fluid 14 to be measured flowing through the piping path 12 is calculated based on the impedance value.

In the second embodiment, the two-electrode method or the four-electrode method can be used as in the first embodiment. However, in the second embodiment, the four-electrode method is used.
Specifically, such a conductivity measuring device 10 applies an AC voltage between two pairs of electrodes arranged in the measurement unit 20 of the sub-flow path 36 of the piping path 12 and between the electrodes 22a and 22b. A conductivity sensor 24 that measures a current value between the electrodes 22a and 22b and a voltage value between the electrodes 22c and 22d, and a voltage value between the electrodes 22c and 22d measured by the conductivity sensor 24, It has at least a calculation unit 26 that obtains the impedance values of the entire flow path 36 and the main flow path 18 and calculates the conductivity of the fluid 14 to be measured by applying a predetermined calculation process to the impedance values.

In the measurement unit 20, the fluid 14 to be measured passes through the two paths of the main flow path 18 and the sub flow path 36.
In addition, since structures other than the measurement part 20 of the piping path | route 12 are the same as that of Example 1, description is abbreviate | omitted.

  As in the first embodiment, the conductivity measuring apparatus 10 is provided with a controller 30 as shown in FIG. 3 separately from the apparatus main body 21, and the controller 30 calculates the conductivity of the fluid 14 to be measured. And an output unit 28 that outputs the conductivity of the fluid 14 to be measured calculated by the calculation unit 26.

  By the way, in the conductivity measuring apparatus 10 according to the second embodiment of the present invention, the following calculation process is performed particularly in the calculation unit 26 described above, and various numerical values used in the calculation process are as follows. This will be described with reference to the schematic diagram of the piping path shown in FIG.

  In the calculation unit 26 according to the present invention, as shown in FIG. 7, first, the electrode 22a and the electrode 22b are calculated from the length (t) between the electrodes 22a and 22b of the sub-flow channel 36 and the entire length of the sub-flow channel 36. A length (T) obtained by adding the length obtained by subtracting the length between the channels and the overall length of the main flow path 18 is input.

Next, a length obtained by subtracting a length between the electrode 22a and the electrode 22b from a length of the entire sub-channel 36 with respect to a length (t) between the electrode 22a and the electrode 22b of the sub-channel 36, and a length of the entire main channel 18 The ratio of the length (T) obtained by adding is calculated.

  Assuming that the ratio of t to T is t: T = 1: a, the following formula (6) is obtained.

Further, the above-mentioned ratio of t: T length is the length between the electrode 22a and the electrode 22b based on the impedance value (X) between the electrode 22a and the electrode 22b of the sub-channel 36 and the total length of the sub-channel 36. Is the same as the ratio of the impedance value (X1) of the length portion obtained by adding the length minus the length of the main flow path 18 as a whole,
The relationship of t: T = X: X1 = 1: a is established, and from this, the following formula (7) is obtained.

This relationship is established when the inner diameter (h) of the main flow path 18 and the inner diameter (H) of the sub-flow path 36 are the same size. In the present embodiment shown in FIGS. The inner diameter (h) of the main flow path 18 and the inner diameter (H) of the sub flow path 36 are different.

  For this reason, taking into account the cross-sectional area ratio of each inner diameter, after converting the inner diameter (h) of the main flow path 18 to be the same as the inner diameter (H) of the sub-flow path 36, the above formula (6) is obtained. The length obtained by subtracting the length between the electrodes 22a and 22b from the total length of the sub-channel 36 with respect to the length (t) between the electrodes 22a and 22b of the sub-channel 36 and the length of the main channel 18 as a whole. What is necessary is just to obtain | require the ratio of the length (T) which added.

  Here, the length between the electrode 22a and the electrode 22b is calculated from the entire length of the hypothetical sub-channel 36, which is calculated that the inner diameter (h) of the main channel 18 is the same as the inner diameter (H) of the sub-channel 36. The length obtained by adding the drawn length and the entire length of the main flow path 18 is calculated by the following mathematical formula (8).

Here, the impedance value (X0) of the fluid 14 to be measured between the electrodes obtained from the AC voltage between the electrodes and the current flowing between the electrodes is equal to the impedance value (X) between the electrodes 22a and 22b. The impedance value (X1) of the length portion obtained by adding the length obtained by subtracting the length between the electrodes 22a and 22b from the overall length of the path 36 and the overall length of the main flow path 18 is synthesized.

  The relationship of X0, X, and X1 is as the following formula (9) which is the formula of the combined resistance.

Substituting Equation (7) into Equation (9) above yields Equation (10) below.

Therefore, for example, the length (t) between the electrode 22a and the electrode 22b disposed in the sub-channel 36 is 110 mm, and the length (t) between the electrode 22a and the electrode 22b is subtracted from the total length of the sub-channel 36. A length of 210 mm, a length of the connecting pipe line 39 in which both ends of the sub-flow path 36 are connected in the main channel 18 is 220 mm, and a length obtained by subtracting the connecting pipe line 39 from the entire length of the main channel 18. If the inner diameter of 2000 mm, the inner diameter of the sub-channel 36 is 5 mm, and the inner diameter of the main channel 18 is 10 mm, by substituting each value into the above equation (8), the electrode 22a can be calculated from the entire length of the virtual sub-channel 36. And the length obtained by subtracting the length between the electrodes 22b and the total length of the main flow path 18 (T):

Is calculated.
Substituting the value of T and the value of t into equation (6),

Will be calculated.
And if this constant a = 2.360 is substituted into the above equation (10),

It becomes.
For this reason, the impedance value (X) between the electrodes 22a and 22b is 1.424 times the impedance value (X0) of the fluid to be measured between the electrodes obtained from the AC voltage between the electrodes and the current flowing between the electrodes. It is obtained by doing. What is necessary is just to multiply 1.424 times also when calculating | requiring the impedance between the electrode 22c and the electrode 22d.

  That is, if the impedance value of the fluid to be measured between the electrodes obtained from the AC voltage between the electrodes 22c and 22d and the current flowing between the electrodes 22a and 22b is, for example, 100Ω, between the electrodes 22a and 22b The impedance value (Xcd) of

It becomes.
Then, the electrical conductivity of the fluid to be measured is calculated by multiplying the impedance value (Xcd) between the electrode 22c and the electrode 22d by a predetermined coefficient, and the electrical conductivity of the fluid to be measured is calculated as the output unit 28 of the controller 30. It is possible for the measurer to visually recognize the information.

  If the above-described calculation unit 26 stores in advance a relational expression between the conductivity and concentration of a known fluid 14 to be measured, the concentration of the fluid 14 to be measured is calculated from the calculated conductivity of the fluid 14 to be measured. Can be calculated.

  In addition, in the output unit 28, not only the conductivity of the fluid 14 to be measured but also the resistivity and the concentration that are the reciprocal of the conductivity can be displayed. That is.

  Further, the controller 30 may be provided with a temperature display unit 31 for displaying the temperature of the fluid 14 to be measured in addition to the conductivity and concentration of the fluid 14 to be measured. In this case, a temperature sensor is separately provided. Can fulfill the function. As described above, functions to be added in addition to the conductivity and concentration of the fluid 14 to be measured can be appropriately added depending on the use environment.

  As described above, the conductivity measuring device and the conductivity measuring method in the second embodiment described above can accurately measure the conductivity and concentration of the fluid to be measured by performing the above-described arithmetic processing in the calculation unit. Is.

The first embodiment and the second embodiment, which are preferred embodiments of the present invention, have been described above. However, the present invention is not limited to the above-described embodiment. For example, in the first and second embodiments, the controller 30 is a device main body. Although separately provided, various modifications can be made without departing from the object of the present invention, for example, the apparatus main body and the controller may be integrally configured.

FIG. 1 is an explanatory diagram for explaining a use state of the conductivity measuring device according to the first embodiment of the present invention. FIG. 2 is an enlarged view of the conductivity measuring apparatus shown in FIG. FIG. 3 shows a controller used in the conductivity measuring device of the present invention. FIG. 4 is a schematic diagram for explaining numerical positions used when the conductivity of the fluid to be measured is calculated by the calculation unit of the conductivity measuring apparatus shown in FIG. FIG. 5 is an explanatory diagram for explaining a use state of the conductivity measuring device according to the second embodiment of the present invention. 6 is an enlarged view of the conductivity measuring apparatus shown in FIG. FIG. 7 is a schematic diagram for explaining numerical positions used when the conductivity of the fluid to be measured is calculated by the calculation unit of the conductivity measuring device shown in FIG. FIG. 8 is a schematic diagram of a piping path using a conventional measuring apparatus. FIG. 9 is a schematic diagram of a piping path using a conventional measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Conductivity measuring device 12 ... Piping path 14 ... Fluid to be measured 16 ... Tank 18 ... Main flow path 20 ... Measuring part 21 ... Main body 22a ... Electrode 22b -Electrode 22c-Electrode 22d-Electrode 24 ... Conductivity sensor 26 ... Calculation part 28 ... Output part 30 ... Controller 31 ... Temperature display part 32 ... Heat exchanger 34- ··· Pump 36 ··· Sub flow channel 39 ··· Connection pipe N1 ··· Non-conductive portion N2 ··· Non-conductive portion 100 ··· Measuring device 102 · · · Electrode 104 · · · External piping 200 ·· Measuring device 202 ... electrode 204 ... external piping 206 ... cover (insulator)

Claims (14)

An electrode is arranged at a predetermined position of the main flow path of the piping path so as to be in contact with the fluid to be measured flowing through the piping path, and the impedance value between the electrodes is calculated from the current flowing between the electrodes and the voltage between the electrodes. A conductivity measuring device that measures and calculates the conductivity of a fluid to be measured based on this impedance value,
The conductivity measuring device is:
At least a pair of electrodes arranged in a measurement part of the main flow path of the piping path;
A conductivity sensor that applies an alternating voltage between the electrodes and measures a current value flowing between the electrodes;
By obtaining an impedance value of a path portion made of non-conductive piping out of the entire piping path based on a current value flowing between the electrodes measured by the conductivity sensor, and performing predetermined arithmetic processing on this impedance value A calculation unit for calculating conductivity of the fluid to be measured;
Having at least
In the calculation unit,
The ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. Calculate
Impedance value of the entire piping path;
From the ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. , Calculating only the impedance value between the electrodes,
A conductivity measuring apparatus configured to calculate the conductivity of the fluid to be measured based on the impedance value. An electrode is arranged at a predetermined position of a sub-flow path formed by branching separately from the main flow path of the piping path so as to come into contact with the fluid to be measured flowing through the piping path, and a voltage is applied between the electrodes to flow. A conductivity measuring device that measures an impedance value between electrodes from a current and a voltage between electrodes, and calculates the conductivity of a fluid to be measured based on the impedance value,
The conductivity measuring device is:
At least a pair of electrodes arranged in a measurement part of a sub-flow path of the piping path;
A conductivity sensor for applying an alternating voltage to the electrodes and measuring a current value flowing between the electrodes;
Calculation that obtains the impedance value of the entire piping path based on the current value flowing between the electrodes measured by the conductivity sensor, and calculates the conductivity of the fluid to be measured by applying a predetermined arithmetic process to the impedance value And
Having at least
In the calculation unit,
A ratio of a length (T) obtained by adding a length obtained by subtracting the inter-electrode length from the entire length of the sub-channel to the inter-electrode length (t) of the sub-channel and the length of the entire main channel is calculated. And
Impedance value of the entire piping path;
From the ratio of the length obtained by subtracting the length between the electrodes from the total length of the sub-channel to the length between the electrodes of the sub-channel (t) and the length of the entire main channel (T), Calculate only the impedance value between the electrodes,
A conductivity measuring apparatus configured to calculate the conductivity of the fluid to be measured based on the impedance value.   The conductivity measuring apparatus according to claim 1, further comprising an output unit that outputs the conductivity calculated by the calculating unit.   The conductivity measuring apparatus according to any one of claims 1 to 3, wherein the electrode is horizontally provided along the flow direction of the piping path.   5. The conductivity measuring apparatus according to claim 1, wherein the number of the electrodes is either one pair or two pairs.   6. The conductivity according to claim 1, wherein the fluid to be measured is a chemical fluid for removing impurities and oxides attached to the surface of the silicon wafer and has conductivity. measuring device. The calculation unit
The conductivity measuring device according to claim 1, which has a function of calculating a concentration of the fluid to be measured based on the calculated conductivity of the fluid to be measured. An electrode is arranged at a predetermined position of the main flow path of the piping path so as to be in contact with the fluid to be measured flowing through the piping path, and the impedance value between the electrodes is calculated from the current flowing between the electrodes and the voltage between the electrodes. A conductivity measurement method for measuring and calculating the conductivity of a fluid to be measured based on this impedance value,
The conductivity measuring method is:
Disposing at least a pair of electrodes in the measurement part of the main flow path of the piping path;
Applying an alternating voltage between the arranged electrodes through a conductivity sensor to measure a current value flowing between the electrodes;
Based on the value of the current flowing between the electrodes measured by the conductivity sensor, the calculation unit obtains an impedance value of a path portion made of a non-conductive pipe in the entire pipe path, and performs a predetermined calculation process on this impedance value. Calculating the conductivity of the fluid to be measured by applying
Having at least
In the step of calculating the conductivity of the fluid to be measured,
The ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. Calculate
Impedance value of the entire piping path;
From the ratio of the length (L) obtained by subtracting the length between the electrodes from the length of the path portion made of a non-conductive pipe in the entire pipe path with respect to the length (l) between the electrodes arranged in the measurement unit. , Calculating only the impedance value between the electrodes,
A conductivity measuring method, wherein the conductivity of the fluid to be measured is calculated based on the impedance value. An electrode is arranged at a predetermined position of a sub-flow path formed by branching separately from the main flow path of the piping path so as to come into contact with the fluid to be measured flowing through the piping path, and a voltage is applied between the electrodes to flow. An electrical conductivity measurement method for measuring an impedance value between electrodes from a voltage between an electric current and an electrode, and calculating an electrical conductivity of a fluid to be measured based on the impedance value,
The conductivity measuring method is:
Arranging at least a pair of electrodes in the measurement part of the sub-flow path of the piping path;
Applying an alternating voltage between the arranged electrodes through a conductivity sensor to measure a current value flowing between the electrodes;
Based on the value of the current flowing between the electrodes measured by the conductivity sensor, the calculation unit obtains the impedance value of the entire piping path, and performs a predetermined calculation process on the impedance value to thereby determine the conductivity of the fluid to be measured. Calculating
Having at least
In the step of calculating the conductivity of the fluid to be measured,
A ratio of a length (T) obtained by adding a length obtained by subtracting the inter-electrode length from the entire length of the sub-channel to the inter-electrode length (t) of the sub-channel and the length of the entire main channel is calculated. And
Impedance value of the entire piping path;
From the ratio of the length obtained by subtracting the length between the electrodes from the total length of the sub-channel to the length between the electrodes of the sub-channel (t) and the length of the entire main channel (T), Calculate only the impedance value between the electrodes,
A conductivity measuring method, wherein the conductivity of the fluid to be measured is calculated based on the impedance value.   The conductivity measuring method according to claim 8, further comprising a step of outputting the conductivity calculated in the step of calculating the conductivity at an output unit.   The conductivity measuring method according to claim 8, wherein the electrodes are provided horizontally so as to follow the flow direction of the piping path.   The conductivity measuring method according to claim 8, wherein the number of the electrodes is either one pair or two pairs.   The electrical conductivity according to any one of claims 8 to 12, wherein the fluid to be measured is a chemical fluid for removing impurities and oxides attached to the surface of the silicon wafer and having conductivity. Measuring method. The calculation unit
The conductivity measuring method according to claim 8, further comprising a function of calculating a concentration of the fluid to be measured based on the calculated conductivity of the fluid to be measured.