JP2865771B2 - Automatic liquid management device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic liquid management device that uses an absorbance to determine whether a processing liquid has deteriorated.

2. Description of the Related Art Conventionally, for example, a cleaning liquid (treatment liquid) used in a semiconductor manufacturing process or the like has been analyzed and managed by various methods regardless of automatic or manual.

Specifically, when analyzing a resist stripping solution (processing solution) used in a manufacturing process of a silicon wafer for a semiconductor, neutralization titration and oxidation-reduction titration of sulfuric acid and hydrogen peroxide which are components of the resist stripping solution are performed. Or by measuring the absorbance of the resist stripping solution and its change with an absorbance meter,
The degree of deterioration of the resist stripping solution was measured.

The resist stripping solution is colored by a resist (novolak resin or the like) laminated on the upper surface of the silicon wafer for semiconductor (object to be processed). The resist stripping solution is treated with sulfuric acid and hydrogen peroxide as components of the resist stripping solution. The resist is decolorized by being decomposed. by this,
By observing the absorbance and the change in absorbance of the resist stripping solution, it is determined whether the resist is present in the stripping solution and whether the resist is effectively decomposed by sulfuric acid or hydrogen peroxide. Is what is done.

[Problems to be Solved by the Invention] By the way, in the method for determining the deterioration of the resist stripping solution as described above, the determination is made based only on the absorbance deterioration per unit time of the resist stripping solution. There was a problem that it was not possible to determine whether or not the measurement was made in terms of absorbance, thereby making it impossible to perform an accurate analysis. Specifically, even if it is determined that the change in absorbance is small and thereby the resist stripping solution is deteriorated, as long as the change in absorbance is made at a low level,
This resist stripping solution is in an active state, and in this regard, provision of a new criterion has been demanded.

The present invention has been made in view of the above circumstances, and has two parameters of an absolute value of absorbance and a change of absorbance with respect to time. The purpose is to provide the device.

"Means for Solving the Problems" In order to achieve the above object, in the present invention, an absorbance measuring means for measuring the absorbance of the treatment liquid at regular time intervals, and analyzing the degree of deterioration of the treatment liquid based on the absorbance Analysis means, and further, the peak of the absorbance is not less than a preset reference absorbance, and the time from the absorbance peak to the reference absorbance is not less than the preset reference time. In some cases, a deterioration determination function for determining deterioration is provided in the analysis means.

According to the present invention, the change in absorbance with respect to time and the two parameters of whether or not the absorbance peak is equal to or greater than a predetermined reference absorbance (absolute value) are determined by:
Since it is determined whether or not the processing solution has deteriorated, for example, when the absorbance of the processing solution slightly changes at a low level after the introduction of the resist, it is possible to determine an error that the processing solution has deteriorated. Is prevented. As a result, an effect that a highly accurate deterioration determination can be performed can be obtained.

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

First, a schematic configuration of the entire automatic liquid management apparatus will be described with reference to FIG. 1 (A). In the figure, reference numeral 1 denotes a processing liquid supply path through which a processing liquid is supplied.

Examples of the treatment liquid include those containing components such as sulfuric acid and hydrogen peroxide that dissolve the resist (eg, novolak resin) on the silicon wafer for semiconductors and dissolve the resist.

In the middle of the processing liquid supply path 1, the processing liquid flow direction X
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 provided in this order.

The photocell 4 guides the resist stripping solution sent by the path 1 into a cell (not shown), and irradiates the resist stripping solution with a light beam having a certain wavelength to measure the absorbance of the resist stripping solution. The measured absorbance is supplied to the data processor M as measurement data (a). As shown in FIG. 1B, the data processing device M
3. It is constituted by an input means 104 and a display panel 105 which is an output means.

The processing of the detection data (a) by the control means 103 of the data processing device M will be described in detail with reference to the flowchart of FIG.

The six-way solenoid valve 5 is (1) normally arranged as shown by a solid line, and the processing liquid is supplied to a processing tank (not shown) through the loop 10 and the paths 6.7 and drained through the paths 6.8. Each is guided to the tank 9. (2) When measuring the concentrations of sulfuric acid and hydrogen peroxide in the treatment liquid, the treatment liquid is switched to the position shown by the dotted line, and the treatment liquid temporarily stored in the loop 10 while being disposed at the position of the solid line is purified water. It is extruded by pure water sent through a supply system 11 (described later) and guided to a reaction cell (described later).

In the loop 10, the amount of the processing liquid stored in the loop 10 is set in advance, that is, used for quantitative determination.

In addition, what is provided at the branch portion of the paths 6 to 8 is as follows:
In particular, a three-way solenoid valve 12 for guiding a dirty processing liquid to the drain tank 9, a pump 13 provided in the middle of the passage 6, a pump 13 provided in the middle of the passage 8,
This is a PH electrode 14 for measuring PH.

The pure water supply system 11 includes a two-way solenoid valve 16, an intermediate trap 17, and a pump 18 provided along a pure water supply path 15.
And a relief valve 20 provided in the branch path 19 for maintaining the supply pressure of the pure water at a certain value or less. 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 processing liquid pushed out by the pure water is supplied to the reaction cells 25 and 23 by the paths 21 to 23 and the three-way solenoid valve 24 provided at a branch portion of the paths 21 to 23.
You are selectively guided to 26.

Further, the reaction cells 25 and 26 are provided with reagent supply systems 27 to 29 for supplying reagents to the processing liquid supplied through the paths 22 and 23, and the oxidation and reduction of the solution in the reaction cells 25 and 26. Oxidation-reduction electrodes 30 and 31 for measuring a potential are provided.

The reagent supply system 27 to 29 supplies the reagent stored in the flasks 27A to 29A little by little to the reaction cells 25 and 26 via the paths 27C to 29C by the titration pumps 27B to 29B, The oxidation-reduction electrodes 30 and 31 are for detecting the oxidation-reduction potential of the treatment liquid when the reagent is dropped, and the sulfuric acid and hydrogen peroxide concentrations of the treatment liquid can be calculated from the change in the oxidation-reduction potential. Has become.

In other words, the point at which the oxidation-reduction potential jumps is defined as the end point of the reaction, and the amount of the reagent dropped at the end point of the reaction (data indicating the amount of dropping is output from the titration pumps 27B to 29B to the control means 103 described later) From the sulfuric acid of the treatment solution,
Each of the hydrogen peroxide concentrations is calculated.

As the reagent stored in the flasks 27A to 29A, an alkali standard solution such as sodium hydroxide, a standard solution causing an oxidation-reduction reaction such as a potassium permanganate solution, an acid standard solution such as sulfuric acid, and the like are suitable. .

On the other hand, at the lower part of the reaction cells 25 and 26, a path 32 for discharging the processing solution in the reaction cells 25 and 26 every time the measurement is completed.
In the middle of these paths 32 to 34, filters 35 and 36, two-way solenoid valves 37 and 38 for performing an operation of discharging the solution from the reaction cells 25 and 26, and a drain pump 39 are sequentially arranged. Is provided. Then, the solution discharged through the paths 32 to 34 is sent to the above-described drain tank 9.

In the above configuration, the configuration in the range indicated by reference numeral 100 in FIG. 1A is defined as sampling means, the configuration in the range indicated by reference numeral 101 is defined as titration means, and the configuration in the range indicated by reference numeral 102 is defined as discharge means.

Next, the control content of the control means indicated by reference numeral 103 in FIG. 1B will be described with reference to a graph showing a change in absorbance with respect to time in FIG. 2 and a flowchart in FIG.

In FIG. 2, when a certain amount of resist is continuously introduced with a certain time interval as shown in FIG. 2, immediately after the introduction, the absorbance increases, but sulfuric acid, which is a component of the processing solution,
The resist is decomposed by hydrogen peroxide, thereby reducing the absorbance. However, the degree of the decrease in the absorbance differs depending on the degree of deterioration of the processing liquid, and the degree of deterioration is determined by the flowchart shown in FIG.

Here, referring to FIG. 2, each input indicated by is individually described. In the first resist input indicated by, the treatment liquid is sufficiently active, and the absorbance and the change amount of the absorbance with respect to time are not so large. However, when the resist is charged as indicated by the symbol, the absorbance temporarily and the amount of change in the absorbance with respect to time are temporarily increased. However, in the above,
After a predetermined time from the introduction of the resist, the increased absorbance has decreased to a certain level or less, indicating that the treatment liquid has not deteriorated yet.

On the other hand, in the loading of the resist indicated by, after the loading,
Although the absorbance increases, the absorbance does not decrease so much after that, and when the resist is charged, the absorbance that has increased after the addition does not decrease at all, indicating that the processing solution has been completely degraded.

Here, each peak value of the peak of the resulting absorbance by ~ a a ₁ ~a _5, each peak value a ₁ ~a ₅ is, t the time to reach up to the absorbance a _o as a reference set in advance respectively ₁ ~ T ₅
When, although specific values for t _2, t ₃ are determined, for t _1, not reach the reference value a _o because it does not exceed the a _o, also for t _4, t ₅ is absorbance does not drop to the reference value a _o, therefore it is impossible to detect the value _{(t 1, t 4, t} 5).

Note that t ₂ and t ₃ have a relationship of “t ₂ <t ₃ ”, and as the number of inputs and the number of inputs increase, the deterioration proceeds and the value of t tends to increase.

The following (1) and (2) summarize the processing liquid deterioration determination criteria based on the above background. (1) Absorbance peak an is _equal to or greater than the predetermined reference absorbance _ao it is, from the peak a _n of (two) absorbance, time until the absorbance a _o as the reference is intended to determine the deteriorated condition that is previously set reference become time t _o or more. Thus, the pattern of the change in absorbance after the resist is input can be assumed, and when the decrease time of the absorbance exceeds a certain time t _o , it is regarded as deteriorated.

With reference to FIG. 3, a description will be given of a flow of determining the deterioration of the processing liquid using the above-described deterioration determination criteria (1) and (2). Note that this deterioration determination flow represents the deterioration determination function of the control unit 103.

Step N shown in the following description corresponds to “SPn” in FIG.

<Step 1> Start.

Set <Step 2> serving as a reference absorbance a _o, and the time from the peak a _n absorbance up to the absorbance a _o as the reference time t _o.

<Step 3> Measurement data indicating absorbance a from photocell 4 (a)
Is taken at regular intervals.

Determined from the variation with time of the captured absorbance a by <Step 4> measurement data (b), the peak value a _n of the absorbance a is set in step 2, whether it is a reference made absorbance: a _o or Then, in the case of YES, the process proceeds to step 5, and in the case of NO, the process returns to step 3.

<Step 5> Based on the absorbance a captured every predetermined time by the measurement data (b), determine the time t _n from the peak a _n absorbance up to the absorbance a _o serving as the reference, the time t _n is, it is determined whether a set reference time t _o or more in step 2, the process proceeds to step 6 if YES, the addition, the flow returns to step 3 in the case of NO.

<Step 6> peak value a _n of the absorbance a is not less serving as a reference absorbance a _o or more and, the absorbance as a reference from the peak a _n of absorbance a _o
If the time t _n up to is equal to or longer than the reference time t _o, it is determined to be deteriorated, and the process proceeds to the next step 7.

<Step 7> An information signal (b) indicating that the processing liquid is deteriorated is output to the display panel 105.

<Step 8 ends.

As described above, according to the automatic fluid management apparatus in this embodiment, (1) whether the peak value a _n of the absorbance a is serving as a reference absorbance a _o or more, from the peak a _n of (two) absorbance The two parameters of whether or not the time t _n to reach the reference absorbance a _o is _equal to or longer than the reference time t _o are used to determine whether or not the processing liquid has deteriorated. In the case where the absorbance of the processing solution changes slightly at a low level (in the case of resist injection), it is not necessary to determine that the processing solution has deteriorated (erroneous), and thus to perform highly accurate deterioration determination. Is obtained.

[Effects of the Invention] As described in detail above, according to the present invention, the change in absorbance with respect to time and whether the peak of absorbance is equal to or greater than a preset reference absorbance (absolute value) or not. Since it is determined whether or not the processing liquid has deteriorated based on the two parameters, it is possible to obtain an effect that highly accurate deterioration determination can be performed.

[Brief description of the drawings]

1 (A) to 3 show one embodiment of the present invention, wherein 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. FIG. 2 is a diagram showing a control device of the management device, FIG. 2 is a graph showing a change in absorbance with respect to the introduction of a resist and time, and FIG. 3 is a flowchart showing control contents of the control device. 4. Photocell (absorbance measuring means) 103 Control means (analyzing means)

Claims (1)

(57) [Claims] 1. An apparatus comprising: an absorbance measuring means for measuring the absorbance of a processing solution at regular intervals; and an analyzing means for analyzing a degree of deterioration of the processing solution based on the absorbance, wherein the peak of the absorbance is set in advance. The analysis means is provided with a deterioration determination function for determining deterioration when the time from the absorbance peak to the reference absorbance is equal to or higher than the reference absorbance is equal to or longer than the predetermined reference time. An automatic liquid management device, characterized in that: