JPH03269357A - Automatic solution management device - Google Patents

Abstract

PURPOSE:To attain accurate concentration measurement by deciding whether the potential of an electrode exceeds a previously set reference value or not and continued for a period more than a previously set value or not. CONSTITUTION:The oxidation-reduction potential of a processing solution at the time of dropping reagent is detected by oxidation-reduction electrodes 30, 31. The jumped point of the oxidation-reduction potential is defined as the end point of reaction, data indicating the dropped quantity of the reagent at the end point of the reaction are outputted from titration pumps 27B to 29B to a control means 100 in a data processor M as detection data (a) and data indicating the oxidation-reduction potential are outputted from the electrodes 30, 31 to the means 100 as detection data (b). When a measured time exceeds the set time, the means 100 decides whether the measured oxidation-reduction potential exceeds the reference value or not based upon the detection data (b). When the decided result is YES, the means 100 calculates the effective component concentration of the processing solution from the dropped quantity of the reagent based upon the data (a) and outputs the calculated result to a display panel 102.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an automatic liquid management device that can automatically manage processing liquid.

"Prior Art" Traditionally, cleaning solutions (processing solutions) used in semiconductor manufacturing processes, etc., have been analyzed and analyzed using various methods, both automatic and manual.
It was managed.

Specifically, the resist stripping solution (processing solution) used in the process of manufacturing silicon wafers for semiconductors undergoes neutralization titration and redox titration of sulfuric acid and hydrogen peroxide, which are the active ingredients of the resist stripping solution. Furthermore, by measuring the absorbance of the resist stripping solution, it has been analyzed whether it can be used continuously.

In addition, the titration of sulfuric acid and hydrogen peroxide, which are the active ingredients, is as follows:
Using a redox electrode, the point at which the redox potential detected by the redox electrode jumps is the end point of the reaction, and the amount of reagent dripped at the end point of the reaction (detected data indicating this dripped amount is output from the titration pump). The concentrations of the active ingredients of the resist stripping solution are calculated from the following.

``Problem to be Solved by the Invention'' By the way, in the method for measuring the active ingredient of a resist stripping solution as described above, depending on the state of dispersion of the reagent being dropped into the resist stripping solution, the reagent may be removed within the time until the next drop. The reagent does not diffuse sufficiently into the resist stripping solution (one drop of the reagent is removed after a certain period of time).
As a result, before the redox potential reaches a steady state, it is determined that the end point has been reached when it is not originally the end point (for example, when the potential exceeds 10,100 O, the end point is reached). There was a problem that accurate analysis could not be performed.

This invention has been made in view of the above circumstances. For example, when the end point potential of 10100O continues for a certain period of time, the dropping amount at the time when this 1000mV is exceeded is taken as the equivalence point. The purpose of the present invention is to provide an automatic liquid management device that can calculate the concentration of active ingredients in a resist stripping liquid and accurately measure the concentration.

"Means for Solving the Problems" In order to achieve the above object, the present invention includes a sampling means for taking in a processing liquid in a processing tank, a reagent being dropped onto the processing liquid sampled by the sampling means, and a titration means for detecting the potential of the electrode of the treatment liquid;
control means for detecting the concentration of the treatment liquid from detection data indicating the dripping amount of the reagent outputted from the titration means and the potential of the electrode; A state determination function is provided to determine whether or not the condition exceeds a set reference value and continues for a preset time period.

"Operation" According to the present invention, a function is provided to determine whether or not the potential of the electrode exceeds a preset reference value and continues for a preset time. The state in which the titration is carried out can be set as the titration equivalence point, that is, the dropped amount exceeding the reference value can be set as the titration equivalence point.

Furthermore, by appropriately adjusting the set time, the equivalence point for titration can be set at the time when the reagent is sufficiently diffused in the treatment liquid and the potential is sufficiently stabilized.

3 "Embodiment" An embodiment of the present invention will be described with reference to FIG. 1(A) and FIG. 1(B) to FIG. 2.

First, the general structure of the automatic liquid management apparatus will be explained with reference to FIG. 1(A). In the figure, what is indicated by the symbol l is a processing liquid supply path through which processing liquid is supplied from a processing tank (not shown).

Note that the processing liquid includes sulfuric acid, which removes and dissolves resist (novolak resin, etc.) on semiconductor silicon wafers;
Contains active ingredients such as hydrogen peroxide.

In the middle of the processing liquid supply path 1, along the flow direction X of the processing liquid, there are a cooler 2 for cooling the processing liquid, a filter 3 for removing impurities such as undissolved substances, a photocell 4, and a six-way solenoid valve 5.
are set up in sequence.

The photocell 4 guides the resist stripping solution sent through the path 1 into the cell (path shown), and measures the absorbance of the resist stripping solution by irradiating the resist stripping solution with a light beam of a certain wavelength. It is something to do.

The six-way solenoid valve 5 (-) is normally arranged as shown by the solid line, and directs the processing liquid to the processing tank (path shown) through the loop 10 and paths 6 and 7, and to the drain through paths 6 and 8. 2) When measuring the concentration of sulfuric acid and hydrogen peroxide in the processing liquid, the liquid was switched to the position shown by the dotted line, and while it was placed at the position shown by the solid line, it was temporarily stored in the loop 10. The processing liquid is transferred to the pure water supply system 11 (
(to be described later) is pushed out by pure water sent through a reaction cell (to be described later).

The loop 10 has a predetermined amount of processing liquid stored therein, that is, it is used for quantitative determination.

Further, provided at the branching portions of the paths 6 to 8 are a three-way solenoid valve 12 for guiding particularly dirty processing liquid to the drain tank 9, and an H electrode 14 in the middle of the path 6.

Further, the pure water supply system 11 includes a three-way solenoid valve 16, an intermediate trap 17, a pump 18, which are provided along the pure water supply route 15, and a branched route 19, so that the supply pressure of the pure water is and a relief valve 20 that maintains the pressure below a certain value. Note that the pure water discharged by the relief valve 20 is guided to the drain tank 9.

On the other hand, the processing liquid that is temporarily stored in the loop 10 and then pushed out by the pure water flows through the paths 21 to 23 and the paths 21 to 23.
A three-way solenoid valve 24 provided at a branch part of 23 selectively guides the reaction cells 25 and 26.

Further, the reaction cells 25 and 26 include the paths 22 and 2.
Reagent supply systems 27 to 29 that supply reagents to the processing liquid supplied by 3, and redox electrodes 30 and 31 that measure the redox potential of the solution in the reaction cells 25 and 26 are provided. There is.

The reagent supply systems 27 to 29 include flasks 27A to 29A.
The reagents stored in the reaction cells 25 and 25 are passed through routes 27C to 29C by titration pumps 27B to 29B.
The oxidation-reduction electrodes 30 and 31 detect the oxidation-reduction potential of the processing solution when the reagent is dropped, and detect the sulfuric acid of the processing solution based on the change in the oxidation-reduction potential. , hydrogen peroxide concentration can be calculated.

In other words, the point at which the redox potential jumps is taken as the end point of the reaction, and the amount of reagent dripped at the end point of the reaction (data indicating this amount of dripping is detected data (a) by the titration pump 27B.
~29B, and data indicating the redox potential are output as detection data (b) from the redox electrodes 30 and 31 to the control means 100 of the data processing device M, which will be described later). The concentrations of the components sulfuric acid and hydrogen peroxide are calculated separately.

The details of the processing of the detection data (a) and (b) by the control means 100 will be described later with reference to the flowchart in FIG.

In addition, the reagents stored in the flasks 27A to 29A include an alkaline standard solution such as sodium hydroxide, a standard solution that causes a redox reaction such as potassium permanganate solution,
An acidic standard solution such as sulfuric acid is suitable.

On the other hand, in the lower part of the reaction cells 25 and 26, paths 32 to 34 are provided for discharging the processing liquid in the reaction cells 25 and 26 each time a measurement is completed. , filters 35 and 36, three-way solenoid valves 37 and 38 for discharging the solution from the reaction cells 25 and 26,
A drain pump 39 is sequentially provided. The solution discharged through the paths 32 to 34 is sent into the drain tank 9 described above.

In the system diagram shown in FIG. 1(A), the range indicated by the - dotted chain line is the titration means 103.

Next, the data processing device M shown in FIG. 1(B) will be explained. This data processing device M includes a control means 100,
It is composed of an input means 101 and a display panel 102 which is an output means.

The control means 100 has a function of determining the state of the treatment liquid, and as shown in the flowchart shown in FIG. Process the detection data (b) respectively, and based on these detection data (a) and (b),
This is to determine whether the processing liquid is in a deteriorated state.

Further, a storage unit (not shown) of the control means 100 stores a reference oxidation-reduction potential (aA) and a set time (C) indicating how long the state exceeding this reference value continues. There is.

Next, the control contents of the control means 100 will be explained with reference to the flowchart shown in FIG.

Note that step N shown in the following explanation corresponds to rsPnJ in FIG.

Step 1> Start <Step 2> Measure the oxidation-reduction potential (ao) based on the detection data (b).

<Step 3> It is determined whether the redox potential (a,) measured in step 2 is equal to or higher than the reference redox potential (aA), and if YES, proceed to step 4; If so, proceed to step 9.

<Step 4> For the titration pumps 27B to 29B, set the dropping amount (bo) at which the dropping amount per - time is the minimum.

<Step 5> to Step 6> The time is measured, and when the measured time has passed the set time (C), proceed to the next step 7.

Step 7> Measure the redox potential (al) based on the detection data (b).

<Step 8> It is determined whether the oxidation-reduction potential (a,) measured in step 7 is equal to or higher than the reference oxidation-reduction potential (aA), and if YES, proceed to step 17;
In this case, proceed to step 9.

<Step 9> The dripping amount (bl) per time is set for the titration pumps 27B to 29B.

Step 10> Measure the redox potential (a,) based on the detection data (b).

<Step 11> It is determined whether the oxidation-reduction potential (a2) measured in step 10 is equal to or higher than the reference oxidation-reduction potential (aA), and if YES, proceed to step 12;
In this case, return to the original step 9.

<Step 12> For the titration pumps 27B to 29B, set the dripping amount (bo) at which the dripping amount per - time is the minimum.

<Step 13> to <Step 14> Time is measured, and when the measured time has passed the set time (C), the process proceeds to the next step 15.

Step 15> Measure the redox potential (a3) based on the detection data (b).

<Step 16> It is determined whether the oxidation-reduction potential (a3) measured in step 10 is equal to or higher than the reference oxidation-reduction potential (aA), and if YES, proceed to step 17; In this case, return to the original step 9.

Step 17> Dropped amount beyond the reference oxidation-reduction potential,
That is, in step 4.12 above.

The point at which the amount of reagent is dropped (the point indicated by the arrow in Figure 3) is the titration equivalence point, and from the amount of reagent dropped at this equivalence point (based on the detection data (a)), the concentration of the active ingredient in the treated liquid is determined. is calculated, and the calculation result is output to the display panel 102.

<Step 18> End As explained above, according to the automatic liquid management device shown in this embodiment, when the potential of the redox electrodes 30 and 31 exceeds the preset reference redox potential (aA), can be,
In addition, when the state in which the redox potential (aA) is exceeded continues for a preset time (c) or more, it is determined that the titration is at the end point, and the amount of the titration exceeds the redox potential (aA). Since the equivalence point function is provided, by appropriately determining the set time (C) in advance, the reagent is sufficiently diffused in the processing liquid 2 and the redox potential is sufficiently stabilized. It can be the end point of the titration.

As a result, as shown by the dotted line in FIG. 3, for example, after the potential of the redox electrodes 30 and 31 exceeds the preset reference redox potential (aA), the redox potential (aA) is immediately changed. If it is below the equivalence point, it is not determined that the equivalence point has been reached, and the reagent is determined to have not been sufficiently diffused in the processing liquid, and the reagent is dripped again.

In the above flowchart, as shown in steps 4 and 12, when the potentials of the redox electrodes 30 and 31 exceed the preset reference redox potential (aA), an even smaller amount (-) is applied. ) was dropped, but this was done to confirm whether or not the potential of the redox electrodes 30 and 31 exceeded the reference redox potential (aA). The amount of the reagent dropped (bo) is a very small amount with respect to the total amount of the reagent dropped to calculate the equivalence point. In addition, the above-mentioned dropping amount (bo) is not limited to this.
may be set to be the same as the dropping amount (b,) shown in step 9.

"Effects of the Invention" As explained in detail above, according to the present invention, a function is provided for determining whether the potential of the electrode exceeds a preset reference value and continues for a preset time period. Therefore, the state determined by this function can be set as the titration equivalence point, that is, the drip amount exceeding the reference value can be set as the titration equivalence point.

In addition, by adjusting the set time as appropriate, the equivalence point for titration can be set at the time when the reagent is sufficiently diffused in the treatment liquid and the potential is sufficiently stable.This allows highly accurate analysis. You can get the effect you want.

[Brief explanation of drawings]

1(A) to 3 show one embodiment of the present invention, FIG. 1(A) is an overall schematic configuration diagram of an automatic liquid management device, and FIG. 1(B) is an automatic liquid management device. A diagram showing the control device of the management device, FIG. 2 is a flowchart showing the control contents of the control device,
FIG. 3 is a graph showing changes in redox potential. Sampling means... [processing liquid supply route 1, six-way solenoid valve 5, route 6, loop 10. Pump 13 (liquid feeding pump)], 100...control means, 103...titration means.

Claims (1)

[Scope of Claims] Sampling means for taking in a processing liquid in a processing tank; titration means for dropping a reagent onto the processing liquid sampled by the sampling means and detecting the potential of an electrode of the processing liquid; control means for detecting the concentration of the treatment liquid from detection data indicating the dripping amount of the reagent outputted from the titration means and the potential of the electrode; the control means has a potential of the electrode set in advance; An automatic liquid management device characterized by being provided with a state determination function for determining whether or not a reference value has been exceeded and continued for a preset time or more.