JPH04320960A - Automatic liquid control device - Google Patents

Abstract

PURPOSE:To enable a device to be simplified by constituting a titration means with a reaction cell for storing a sampled treatment liquid, a reagent supply system for dripping an oxidizer into the treatment liquid, and an electrode for detecting an oxidation reduction potential within the reaction cell. CONSTITUTION:A titration means 50 is constituted by a reaction cell 22 which stores a resist release liquid which is sampled by a loop 10, a reagent supply system 23 for dripping an oxidizer into a treatment liquid as a reagent, and an oxidation reduction electrode 24 for detecting an oxidation reduction potential of a liquid solution within the cell 22. Then, when automatic operation is made, a 6-way electromagnetic valve 5 is switched at each fixed time and a resist release liquid which is titrated by the loop 10 is pushed out by pure water which is fed through a pure water supply system 11 and then is supplied to the cell 22. Then, a titration pump 27 is driven, a reagent for measuring hydrogen peroxide which is stored within a flask 25 is supplied into the flask 25, and then the hydrogen peroxide concentration of the resist release liquid is calculated from the amount of dropped reagent with a point where the oxidation reduction potential Jumped as a final point of reaction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an automatic liquid management device for measuring changes in the composition of a processing liquid.

0002

2. Description of the Related Art Conventionally, cleaning liquids (processing liquids) used, for example, in semiconductor manufacturing processes, have been analyzed and managed by various methods, both automatic and manual. Specifically, when analyzing the resist stripping solution (processing solution) used in the manufacturing process of silicon wafers for semiconductors, the components of the resist stripping solution, such as sulfuric acid and hydrogen peroxide, are analyzed by neutralization titration and redox titration. Alternatively, the degree of deterioration of the resist stripping solution was measured by measuring the absorbance of the resist stripping solution and its change using an absorbance meter.

0003

[Problems to be Solved by the Invention] By the way, in determining the deterioration of the resist stripping solution as described above, the deterioration of the resist hydrogen is measured by measuring the concentrations of both sulfuric acid and hydrogen peroxide. As a result, at least two systems of titration apparatuses were required, and at least two types of reagents had to be prepared accordingly. This invention was made in view of the above-mentioned circumstances, and has a single system of titration means, which simplifies the overall configuration and requires only one type of reagent, making maintenance easier. The purpose is to provide an automatic liquid management device that can keep costs low.

0004

[Means for Solving the Problems] The present invention is constructed based on the following background. First, what is shown in FIG. 1 is the change over time in the hydrogen peroxide concentration in the resist stripping solution (processing solution), and what is shown in FIG. 2 is the change over time in the sulfuric acid concentration in the resist stripping solution. As can be seen from these figures, after the resist is added, the concentration of hydrogen peroxide in the processing solution decreases rapidly, while the concentration of sulfuric acid hardly changes. By observing only the concentration of hydrogen peroxide, it is possible to determine how much the resist stripping solution has deteriorated. Based on such points of view, the present invention includes a sampling means for sampling a treatment liquid, a titration means for determining the hydrogen peroxide concentration of the sampled treatment liquid by titration, and further includes:
The titration means includes a reaction cell that stores the sampled treatment liquid, a reagent supply system that drops an oxidizing agent as a reagent that oxidizes hydrogen peroxide in the treatment liquid, and detects the redox potential in the reaction cell. The structure is made up of electrodes.

[0005]

[Operation] According to the present invention, a reagent as an oxidizing agent for oxidizing hydrogen peroxide is dripped into the sampled treatment liquid by a single titration means consisting of a reaction cell, a reagent supply system, and an electrode. The concentration of hydrogen peroxide in the treatment liquid is measured based on the amount of the reagent dropped and the redox potential in the reaction cell. In other words, the degree of deterioration of the treatment liquid can be detected with a single system of titration means for measuring hydrogen peroxide in the treatment liquid, so the configuration is simplified compared to conventional automatic liquid management devices. In addition, since only one type of reagent is required to be supplied to the reagent supply system of one titration means, maintenance is facilitated.

[0006]

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. An embodiment of the present invention will be described with reference to the overall schematic configuration diagram of FIG. 3 and the flowchart of FIG. 4. First, in FIG. 3, the reference numeral 1 indicates a processing liquid supply path through which a resist stripping liquid (processing liquid) is supplied. In addition,
The resist stripping solution contains components such as sulfuric acid and hydrogen peroxide that strip and dissolve the resist (novolak resin, etc.) on the semiconductor silicon wafer. In the middle of the processing liquid supply path 1, along the flow direction X of the resist stripping solution, there are a cooler 2 for cooling the resist stripping solution, a filter 3 for removing impurities such as undissolved substances, a photocell 4, and a hexagonal solenoid valve. 5 are provided in sequence. The photocell 4 guides the resist stripping solution sent through the path 1 into a cell (not 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. Then, based on the change in absorbance detected by this photocell 4, the degree of deterioration of the processing liquid is measured.

Further, the six-way solenoid valve 5 is (1) usually arranged as shown by a solid line, and the resist stripping liquid is passed through a loop 10 and paths 6 and 7 to a processing tank (not shown).
(2) When measuring the hydrogen peroxide concentration in the resist stripping solution, switch to the position shown by the dotted line, and while it is placed at the position shown by the solid line. The resist stripping solution temporarily stored in the loop 10 is pushed out by pure water sent through a pure water supply system 11 (described later) and guided to a reaction cell (described later). Note that the loop 10 has a preset amount of resist stripping liquid stored therein, that is, is used for quantitative determination. Further, a three-way solenoid valve 12 is provided at the branching part of the paths 6 to 8 for guiding particularly dirty resist stripping liquid or a liquid mixed with pure water to the drain tank 9, and a three-way solenoid valve 12 is installed in the middle of the path 6. The pump 13 is installed in the middle of the path 8, and the pump 13 is installed in the middle of the path 8.
This is a PH electrode 14 that measures the PH of the resist stripping solution.

Further, the pure water supply system 11 includes a two-way solenoid valve 16, an intermediate trap 17, a pump 18, which are provided along the pure water supply path 15, and a branched path 19, to supply the pure water. The relief valve 20 maintains the water supply 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, after being temporarily stored in the loop 10, the resist stripping liquid pushed out by the pure water is guided to the titration means 50 through the path 21. The titration means 50 includes a reaction cell 22 that stores the resist stripping solution sampled by the loop 10, and a reaction cell 22 that stores the resist stripping solution sampled by the loop 10.
The reagent supply system 23 drops an oxidizing agent that oxidizes hydrogen peroxide in the resist stripping solution as a reagent, and the oxidation-reduction potential of the solution in the reaction cell 22 is measured. It is composed of a redox electrode 24 for detecting the degree of reactivity between hydrogen peroxide and a reagent, and a system of titration means 50 having such a structure is provided.

The reagent supply system 23 includes a flask 25 storing a potassium permanganate solution that oxidizes hydrogen peroxide in the resist stripping solution, and a path 26 that guides the reagent in the flask 25 into the reaction cell 22. And this route 26
A titration pump 2 is installed in the middle of the process to supply the reagent in the flask 25 little by little to the reaction cell 22 and drip it.
It is composed of 7. Then, from the titration means 50 configured as described above, detection data (a) indicating the redox potential measured at the redox electrode 24 is output.
and dripping amount data (b) indicating the dripping amount measured by the titration pump 27 are stored in a data processing device (not shown).
The data processing device measures the hydrogen peroxide concentration in the resist stripping solution. That is, in the data processing device, the point at which the redox potential jumps is taken as the end point of the reaction (based on the detection data (a)), and the amount of reagent dropped at the end point of the reaction (based on the dropped amount data (b)) is determined. , the hydrogen peroxide concentration of the resist stripping solution is calculated.

On the other hand, a path 30 is provided at the bottom of the reaction cell 22 for discharging the resist stripping solution in the reaction cell 22 every time a measurement is completed, and a filter 31, A solenoid valve 32 and a drain pump 33 for discharging the solution from the reaction cell 22 are provided in this order. The solution discharged through the path 32 is sent into the drain tank 9 described above. In the above configuration, the components in the range indicated by numeral 100 in FIG. 3 are used as sampling means, the components in the range indicated by numeral 50 are used as titration means, and the components in the range indicated by numeral 60 are used as discharge means.

Next, the control contents of the automatic liquid management device shown in FIG. 3 will be explained step by step with reference to the flowchart shown in FIG. Note that this control content is stored in a control device (not shown) and executed by the control device. Further, the operator's instructions given in the following explanation are given on an operation panel (not shown). <<Step 1>> Determine whether there is an instruction (from the operator) to set the date and time of measurement. If YES, proceed to step 2; if NO, proceed to step 3. <Step 2> Set the date and time. <<Step 3>> Determine whether there is an instruction (from the operator) to set measurement conditions. If YES, proceed to step 4; if NO, proceed to step 5. <Step 4> Input measurement conditions. Note that the measurement conditions include a measurement cycle time that indicates how many cycles the concentration analysis of the resist stripping solution is performed.

<<Step 5>> If there is an instruction (from the operator) to analyze the concentration of hydrogen peroxide, the process proceeds to the next step 6. <<Step 6>> Set the solenoid valve 32 to the open state. <<Step 7>> The titration pump 27 and the drainage pump 33 are operated for a certain period of time, and the inside of the path 26 is replaced with the reagent for hydrogen peroxide concentration analysis stored in the flask 25. The reagent for hydrogen peroxide analysis that has been substituted into the path 26 is discharged into the drain tank 9 through the path 30 because the solenoid valve 32 is set to the open state. <Step 8> Set the solenoid valve 32 to the closed state. 《Step 10》Determine whether or not to perform automatic driving,
If YES, proceed to step 12; if NO, proceed to step 11.

<Step 11> (Manual operation) Switch the hexagonal solenoid valve 5 from the position shown by the solid line to the position shown by the dotted line,
The resist stripping solution quantified in the loop 10 is pushed out by pure water sent through a pure water supply system 11 (described later) and guided to the reaction cell 22. Next, titration pump 27
is driven, and the reagent for measuring hydrogen peroxide stored in the flask 25 is supplied into the flask 22 little by little. In addition,
The amount of reagent supplied at this time is output as dripping amount data (b). Then, the operator observes the output data (a) of the redox electrode 24, which changes by supplying the reagent, using the numerical values on the display section that displays this, and points out the point where the output data (a) of the electrode has jumped. Read the dripping amount data (b) and calculate the concentration of hydrogen peroxide from this quantitative value. Note that the above-mentioned quantitative determination of the resist stripping solution, dripping of the reagent, etc. are all performed by the operator using keys for each step.

<<Step 12>> (Automatic operation) The six-way solenoid valve 5 is switched from the position shown by the solid line to the position shown by the dotted line at fixed time intervals (set in step 4), and the resist stripping liquid determined in the loop 10 is applied. It is pushed out by pure water sent through a pure water supply system 11 (described later) and guided to the reaction cell 22. Next, after the sample liquid is supplied to the reaction cell 22, the titration pump 27 is driven, and the flask 2
A reagent for hydrogen peroxide measurement stored in advance in the flask 22 is fed into the flask 22 little by little. Note that the amount of reagent supplied at this time is supplied to the data processing device as dripping amount data (b). In the data processing device, the point at which the redox potential jumps is taken as the end point of the reaction (based on the detection data (a)), and from the amount of reagent dropped at this end point of the reaction (based on the dropped amount data (b)), the resist Calculate the hydrogen peroxide concentration of the stripping solution. Note that the above-mentioned quantitative determination of the resist stripping solution, dripping of the reagent, and calculation of the concentration are all automatically performed by a control device (not shown). 《Step 13》Instruction to terminate (from operator)
It is determined whether or not there is, and if NO, the process returns to the original step 10, and if YES, this flow ends.

As explained above, according to the automatic liquid management apparatus shown in this embodiment, as shown in steps 10 to 12, hydrogen peroxide is added to the sampled resist stripping liquid by one system of titration means 50. A potassium permanganate aqueous solution, which is a reagent for analysis, is dropped, and the concentration of hydrogen peroxide in the resist stripping solution is automatically measured using the dropped reagent, thereby measuring the degree of deterioration of the resist stripping solution. That is, with reference to the change in the concentration of hydrogen peroxide after the resist was added to the resist stripping solution in FIG. 1, and the change in the concentration of sulfuric acid after the resist was added to the resist stripping solution in FIG. As can be seen, after the resist is added, the concentration of hydrogen peroxide in the resist stripping solution decreases rapidly, while the concentration of sulfuric acid hardly changes. 10
By monitoring as shown in 12 to 12, it is possible to determine how much the resist stripping solution has deteriorated, and if there is a system of titration means 50 for measuring hydrogen peroxide in the resist stripping solution. , the degree of deterioration of the resist stripping solution can be detected. An automatic liquid management device constructed against this background has a simplified configuration compared to a conventional automatic liquid management device that is equipped with multiple systems of titration means, and the reagents can be handled in one system. Since only one type of reagent is required to be supplied to the reagent supply system of the titration means, maintenance is easy and running costs can be kept low.

[0016] Normally, when hydrogen peroxide is reacted with the reagent potassium permanganate, sulfuric acid (potassium permanganate has different reactivity under acidic and neutral conditions, so However, according to the automatic liquid management device shown in this example, since it is assumed that a sulfuric acid-hydrogen peroxide-based resist stripping liquid will be analyzed, In particular, the step of adding sulfuric acid can be omitted when titrating hydrogen oxide. Furthermore, when quantifying hydrogen peroxide in a resist stripping solution that does not contain sulfuric acid, it is recommended to dissolve the reagent potassium permanganate in an aqueous sulfuric acid solution instead of in pure water. good. This makes it possible to perform quantitative analysis even when the sampled solution (processing liquid) does not contain sulfuric acid (for example, an aqueous solution containing only hydrogen peroxide). Further, the oxidizing agent is not limited to potassium permanganate, but potassium dichromate or the like may be used. Furthermore, when the automatic liquid management device is used, for example, to measure the concentration of sulfuric acid in a resist stripping solution, it is necessary to change the reagent in the flask 25 to one for sulfuric acid analysis (sodium hydroxide). , if changed,
As shown in steps 6 to 8 above, the titration pump 27
It is preferable to replace the inside of the path 26 with the reagent for sulfuric acid analysis by driving the reagent for a certain period of time.

[0017]

Effects of the Invention As is clear from the above description, according to the present invention, the configuration is simplified compared to the conventional automatic liquid management device equipped with multiple systems of titration means, and the reagent can be Since only one type of reagent is required to be supplied to the reagent supply system of one titration means, maintenance is easy and running costs can be kept low.

[Brief explanation of drawings]

FIG. 1 is a graph showing changes in the concentration of hydrogen peroxide after a resist is added to a resist stripping solution (processing solution).

FIG. 2 is a graph showing changes in the concentration of sulfuric acid after a resist is added to a resist stripping solution (processing solution).

FIG. 3 is an overall schematic configuration diagram of an automatic liquid management device.

FIG. 4 is a flowchart showing control details of the control device of the automatic liquid management device.

[Explanation of symbols]

22 Reaction cell 24 Electrode 30 Reagent supply system 50 Titration means 100 Sampling means

Claims (1)

[Claims] 1. A method comprising a sampling means for sampling a treatment liquid, and a titration means for determining the hydrogen peroxide concentration of the sampled treatment liquid by titration, the titration means comprising:
Consisting of a reaction cell that stores the sampled treatment liquid, a reagent supply system that drops an oxidizing agent as a reagent that oxidizes hydrogen peroxide in the treatment liquid, and an electrode that detects the redox potential in the reaction cell. An automatic liquid management device characterized by: