JP2011128455A - Device for measuring concentration of carbonic acid-based salt, system for controlling alkali developing solution, and method for measuring concentration of carbonic acid-based salt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for easily measuring a concentration of carbonic acid-based salts in an alkali developing solution with high accuracy, and to provide a system for controlling an alkali developing solution by using the above device and method. <P>SOLUTION: The device 99 for measuring a concentration of carbonic acid-based salts includes: a data obtaining part 91 obtaining each of the information about the refractive index of an alkali developing solution, the information about the conductivity of the alkali developing solution and the information about the absorbance of the alkali developing solution; and a carbonic acid-based salt concentration obtaining part 94 obtaining the information about the concentration of carbonic acid-based salts in the alkali developing solution on the basis of the information about the refractive index, information about the conductivity and information about the absorbance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a carbonate-based salt concentration measuring device, an alkali developer management system, and a carbonate-based salt concentration measuring method.

  In a photolithography process performed in the process of manufacturing elements on a substrate such as a liquid crystal substrate or a semiconductor substrate, an alkaline developer is repeatedly used to develop wiring and the like. At this time, the alkali developer is often circulated in the atmosphere, and when the alkali developer comes into contact with air, carbon dioxide in the air dissolves in the alkali developer and reacts with the alkali developer components to react with a bicarbonate or Carbonate salts such as carbonate are formed. In order to maintain the development performance of the alkali developer, it is necessary to maintain the composition of the alkali developer component constant. However, if the carbonate salt concentration in the alkali developer is increased, the concentration of the alkali developer component is within the specified range. In some cases, the development performance may deteriorate. For this reason, it is important to measure and manage the concentration of carbonates in the alkaline developer.

  As a method for measuring carbonates in an alkali developer, it is known to directly measure by using an infrared carbon dioxide sensor, an absorptiometer, a neutralization titrator, or a detection device such as chromatography.

JP-A-2005-70351 Japanese Patent No. 4097973

  However, with the conventional method, it has been difficult to measure the concentration of carbonates simply and immediately with high accuracy on a production line or the like.

  The present invention has been made in view of the above problems, and provides an apparatus and method capable of measuring the concentration of carbonates in an alkali developer easily and immediately with high accuracy, and an alkali developer management system using the same. The purpose is to provide.

The carbonate-based salt concentration measuring apparatus according to the present invention includes a data acquisition unit that acquires information about the refractive index of an alkali developer, information about the conductivity of the alkali developer, and information about the absorbance of the alkali developer,
A carbonate salt concentration acquisition unit that acquires information related to the concentration of carbonate salt in the alkali developer based on information on refractive index, information on conductivity, and information on absorbance.

The method for measuring a carbonate salt concentration according to the present invention includes a step of obtaining information on the refractive index of an alkali developer, information on the conductivity of the alkali developer, and information on the absorbance of the alkali developer,
Obtaining information on the concentration of carbonates in the alkali developer based on information on refractive index, information on conductivity, and information on absorbance.

  According to the present invention, the concentration of carbonates in the alkali developer can be determined quickly, simply and with high accuracy. The reason for this is as follows.

The components contained in the alkali developer mainly include alkali developer components, carbonates, and dissolved resists.
The information regarding the refractive index of the alkali developer is information regarding the total concentration of these three components in the alkali developer, and the information regarding the conductivity of the alkali developer is information regarding the concentration of the alkali developer component of the alkali developer. It has been found that the information on the absorbance of the developer is considered to be information on the dissolved resist concentration of the alkaline developer. Then, if the information on the total concentration and the information on the two individual components are known, the information on the carbonate salt concentration, which is the remaining one component, is obtained as a one-to-one function based on these information, for example. Can do.

Here, when the carbonate-based salt concentration acquisition unit has α as the information regarding the refractive index, β as the information regarding the conductivity, and γ as the information regarding the absorbance,
It is preferable to obtain information on the concentration of carbonates based on Aα-Bβ-Cγ + D. Here, A, B, and C are positive constants, and D is a constant.

  According to this, the concentration of carbonate salts can be measured more easily. It is also easy to obtain a constant.

  The alkaline developer management system according to the present invention controls the carbonate salt concentration in the alkali developer based on the carbonate salt concentration measuring device and the carbonate salt concentration obtained by the carbonate salt concentration measuring device. A control unit.

  According to this, since the carbonate salt concentration can be appropriately managed, even when the alkaline developer is recycled for a long time, the developing ability can be maintained at extremely high quality.

  ADVANTAGE OF THE INVENTION According to this invention, the apparatus and method which can measure the density | concentration of carbonate type salt in an alkali developing solution simply and immediately accurately and an alkali developing solution management system using the same are provided.

FIG. 1 is a flowchart of a developer supply apparatus according to an embodiment of the present invention. FIG. 2 shows the adjustment of a resist developer having a different carbonate salt concentration by changing the amount of carbon dioxide dissolved in the resist developer having a TMAH concentration of 2.380% by mass. It is the graph which plotted the density | concentration and refractive index of system salt. FIG. 3 shows a case where a plurality of resist developers having different concentrations of dissolved resist are prepared by changing the amount of resist to be dissolved in a resist developer having a TMAH concentration of 2.380% by mass. It is the graph which plotted the density | concentration and refractive index. FIG. 4 is a graph plotting the TMAH concentration and the refractive index for a resist developer having a different TMAH concentration. FIG. 5 shows an actual measured value (♦) by titration of carbonate salt concentration in an actual developer supply device and an estimated value (□) of carbonate salt concentration obtained by calculation using equation (1). The vertical axis is a graph showing these difference values (Δ) as a function of time on the right vertical axis. FIG. 6 is a graph in which the data of FIG. 5 is plotted with the measured value by titration on the horizontal axis, the estimated value by calculation on the left vertical axis, and the difference between the measured value and the estimated value plotted on the right vertical axis. FIG. 7 is a histogram of the difference values in FIG.

  FIG. 1 is a schematic diagram showing the configuration of a preferred embodiment of a developer supply apparatus according to the present invention. The developer supply apparatus 100 is connected to receive the alkali developer from the development processing apparatus 210 of the liquid crystal panel manufacturing facility 200 through the pipe L1 and the pump 2, and supply the alkali developer from the pipe L2 and the pump 10. The liquid W is circulated and supplied to the development processing apparatus 210. Examples of the development processing apparatus 210 include a roller conveyor system, a spin system, and a cassette batch system.

  Here, in this embodiment, a case where a 2.38% by mass aqueous solution of TMAH (trimethylammonium hydroxide) is used as an alkaline developer will be described as an example.

  In the developing solution supply apparatus 100, the adjustment tank 5 is provided in the rear stage of the receiving tank 1 connected to the pipe L1 via the line L5 having the pump 3 and the valve V5, and the particle remover 7 is provided in the rear stage of the adjustment tank 5. A pipe L2 provided with is connected.

  In the receiving tank 1, the used alkaline developer W used for developing the photoresist in the development processing device 210 is introduced through the pipe L <b> 1.

  The adjusting tank 5 measures the composition of the alkali developer in the receiving tank 1 and adjusts the composition of the alkali developer within a predetermined range by adding a new solution or the like. In the adjustment tank 5, a stirrer M is provided to make the concentration of the alkaline developer uniform. A circulation line L9 having a circulation pump 6 is provided outside the tank to circulate the liquid in the adjustment tank.

  In this circulation line L9, a conductivity meter 50 for measuring the conductivity of the alkali developer, an absorbance meter 51 for measuring the absorbance of the alkali developer, and a refractometer 52 for measuring the refractive index of the alkali developer are connected in series. Is provided. Note that the order of these measuring instruments is not particularly limited, and these measuring instruments may be connected in parallel.

  The conductivity meter 50 measures the conductivity of the alkaline developer in the adjustment tank 5. The conductivity in the alkali developer has a high correlation with the concentration of the alkali developer component of the alkali developer. The conductivity meter is not particularly limited, and for example, an electrode method or an electromagnetic induction method can be used. Here, the alkali developing component measured by the conductivity meter includes dissociation of the alkali developing component that has become carbonate salt in addition to the alkali developing component that is not carbonated salt (for example, TMAH). Can also be included. However, only a part of the alkali developing components that have become carbonates is dissociated.

  The absorbance meter 51 measures the absorbance of the alkali developer in the adjustment layer 5. The absorbance in the alkali developer has a high correlation with the concentration of the dissolved resist in the alkali developer. Although the wavelength used as a measuring object is not specifically limited, It is preferable to measure the light absorbency of any wavelength within 450-600 nm, More preferably, it is either 500-580 nm.

  The refractometer 52 measures the refractive index of the alkaline developer in the adjustment layer 5 with high accuracy. The refractive index in the alkali developer has a high correlation with the total concentration of the alkali developer component, carbonate salt, and dissolved resist of the alkali developer. The measurement principle is not particularly limited, but in particular, a flow-through type that can measure the refractive index in the range of 1.33,000 to 1.35000, which is the fluctuation range of the refractive index of the alkaline developer, with high accuracy is preferable.

  The adjustment tank 5 is provided with a line L4 for discharging the alkaline developer in the adjustment layer 5 out of the system, and the line L4 is provided with a valve V4.

  Further, the developer supply apparatus 100 includes a liquid supply system 8. The liquid supply system 8 includes a pure water supply source 81 connected to the adjustment tank 5 through a pipe L21 having a valve V1, and an alkali developer stock solution supply system connected to the adjustment tank 5 through a pipe L22 having a valve V2. 82 and an alkaline developer new solution supply system 83 connected to the adjustment tank 5 through a pipe L23 having a valve V3.

  The pure water supply source 81 is a device that supplies so-called pure water or ultrapure water whose ion concentration, particle concentration, and the like are appropriately controlled.

  The developer stock solution supply source 82 is a device for supplying a stock solution of an alkali developer that is a TMAH aqueous solution having a concentration higher than 2.38% by mass. For example, a TMAH solution adjusted to an alkali component concentration of about 20% by mass Supply.

  A new developer supply source 83 supplies a new alkali developer set to an alkali concentration used for developing the resist, in this embodiment, a TMAH solution adjusted to an alkali component concentration of 2.38% by mass, for example. To do.

  The control device 9 controls the concentrations of various components of the alkaline developer in the adjustment tank 5 based on information from the conductivity meter 50, the absorbance meter 51, and the refractometer 52. The control device 9 includes a data acquisition unit 91, a carbonate salt concentration acquisition unit 94, a concentration control unit 92, and an output interface 93. Here, the data acquisition unit 91 and the carbonate salt concentration acquisition unit 94 constitute a carbonate concentration measuring device 99.

  The data acquisition unit 91 is an input interface, acquires information β related to conductivity from the conductivity meter 50 via the signal line S1, acquires information γ related to absorbance from the absorbance meter 51 via the signal line S2, and The information α related to the refractive index is acquired from the refractometer 52 via the signal line S3. Data acquisition is usually performed every predetermined time. The sampling interval is, for example, 0.1 to 600 seconds. The signal flowing through the signal line is, for example, an electric signal or an optical signal.

  Note that the information α, β, and γ, which are data handled by the data input unit 91 and the carbonate salt concentration acquisition unit 94, may be the absolute values of the measured values themselves, or may be relative values with respect to a predetermined reference value. Absent.

  The carbonate salt concentration acquisition unit 94 acquires information X relating to the carbonate salt concentration in the alkaline developer based on the three pieces of information α, β, and γ acquired by the data acquisition unit 91. Here, the carbonate salt concentration acquisition unit 94 will be described in detail.

  The components contained in the alkali developer mainly include alkali developer components, carbonates, and dissolved resists. The information α relating to the refractive index of the alkali developer gives information relating to the total concentration of these three components, the information β relating to the conductivity of the alkali developer giving information relating to the concentration of the alkali developer, and the absorbance of the alkali developer. Information γ is considered to give information on the concentration of the dissolved resist.

  Then, information on the total concentration of the three components of the alkali developing component, carbonate salt, and dissolved resist, information on the concentration of two individual components, namely, the concentration of the alkali developing component, and information on the concentration of the dissolved resist Therefore, the information X relating to the concentration of the carbonate salt that is the remaining one component can be obtained as a function of α, β, and γ.

  That is, in the carbonate concentration acquisition unit 94, the functions of the three pieces of information α, β, and γ acquired by the data acquisition unit 91, that is, X = f (α, β, γ), are used for the carbonate salts in the alkaline developer. Obtain information X about the concentration.

  This function may be a so-called mathematical formula or may be in the form of a data table. Such a function can be obtained by a known fitting method by preparing an alkali developer having a composition in which the three components are variously combined. For example, such functions include a linear function, a quadratic function, an exponential function, and the like.

For the sake of simplicity of calculation, the following equation (1) is preferably used as this function.
X = Aα−Bβ−Cγ + D (1)
Here, A, B, and C are positive constants, and D is an arbitrary constant. This equation is obtained from the following assumptions.

  That is, approximately, the total concentration of all components in the alkaline developer (related to α) is the alkali developing component concentration (related to β), the carbonate salt concentration (X), and the dissolved resist concentration (related to α). It is considered that the following formula is established.

α = aβ + bγ + cX + d (a)
Here, a, b, and c are positive constants, and d is an arbitrary constant.

  The units of α, β, γ, and X are not particularly limited, and are, for example, mass%, mol%, and the like.

Solving equation (a) for X,
X = (1 / c) α- (a / c) β- (b / c) γ- (d / c)
= Aα-Bβ-Cγ + D (1)
It becomes.

  For A, B, C, and D, as described above, a plurality of types of alkaline developers with known X, α, β, and γ may be prepared and fitted to the equation (1). Of course, it goes without saying that the fitting may be performed by a function such as a quadratic expression that is more complicated than the expression (1).

  The functions and constants A to D are often different from each other depending on the type of the dissolved resist and the type of the alkali developing component of the alkaline developer, and may be appropriately selected depending on the system. The carbonate salt concentration acquisition unit 92 has a storage unit 94a, and such functions are stored in advance. This makes it possible to indirectly measure the carbonate concentration. The function of the carbonate salt concentration acquisition unit 94 is realized by software that normally operates on a computer.

  The concentration control unit 92 is connected via the output interface 93 based on various information α, β, γ obtained by the data acquisition unit 91 and information X on the carbonate salt concentration obtained by the carbonate salt concentration acquisition unit 94. The valves V1 to V4 are controlled to maintain the concentration of various components of the alkaline developer in the adjustment tank 5 within a certain range. Such a density control unit 92 is realized by software that normally operates on a computer.

  For example, when the information β related to the conductivity exceeds a predetermined range, it is determined that the alkali developing component concentration is too high, the valve V1 is opened, pure water is supplied, and the concentration is lowered. If the electrical conductivity information β is below a predetermined range, the alkali developing component concentration is too low, and the valves V2 and V3 are opened to supply the alkali developing stock solution or new solution to increase the concentration of the alkali developing component. . The suitable density | concentration of the alkali image development component using TMAH is 2.377-2.383 mass%, for example.

  Further, for example, when the information γ relating to the absorbance exceeds a predetermined upper limit, the valve V4 is opened and a part of the developer in the adjustment tank 5 is discarded after the dissolved resist concentration is too high. V3 is opened and a new alkali developer is supplied to lower the dissolved resist concentration. The upper limit of the concentration of the dissolved resist is, for example, 1.0% by mass.

  Further, for example, if the information X about the carbonate salt concentration exceeds a predetermined upper limit, the valve V4 is opened and a part of the developer in the adjustment tank 5 is discarded because the carbonate salt concentration is too high. After that, the valve V3 is opened and a new alkali developer is supplied to lower the carbonate salt concentration. The upper limit of the carbonate salt concentration is, for example, 0.35% by mass.

  A particle remover 7 is connected to a pipe L2 connecting the adjustment tank 5 and the development processing apparatus 210. The configuration of the particle remover 7 is not particularly limited, and examples thereof include an MF film.

  Note that the type of resist developed by the developing device is not particularly limited, and various types can be set corresponding to the alkali developing component. For example, when the alkali developing component is TMAH, for example, novolak resin, diazonaphthoquinone (DNQ) positive resist, and the like can be given.

  An example of the operation of the developer supply apparatus 100 configured as described above will be described.

  The used alkaline developer W used for development is supplied to the receiving tank 1 from the development processing device 210 of the liquid crystal panel manufacturing facility 200 through the pipe L1. Next, the alkaline developer W is supplied from the receiving tank 1 to the adjusting tank 5 through the pipe L5 to which the valve V5 is connected. In the adjustment tank 5, the alkali developer W is stirred by the stirrer M, and a part thereof is circulated through the circulation pipe L <b> 9. Then, the conductivity meter 50, the absorbance meter 51, and the refractometer 52 measure the information β regarding the conductivity of the alkali developer W, the information γ regarding the absorbance, and the information α regarding the refractive index. The data input unit 91 acquires these three pieces of information α, β, and γ through the signal lines S1, S2, and S3. The data input unit 91 periodically acquires these three pieces of information.

  The carbonate-based salt concentration acquisition unit 94 uses a predetermined function as a function of information α regarding the refractive index of the alkali developer, information β regarding the conductivity of the alkali developer, and information γ regarding the absorbance of the alkali developer. Then, information X relating to the concentration of carbonate salt in the alkaline developer is obtained. The carbonate salt concentration acquisition unit 94 periodically acquires information X relating to the carbonate salt concentration of the alkaline developer and transmits the information X to the concentration control unit 92.

  Based on information β relating to the conductivity of the alkaline developer, information γ relating to the absorbance of the alkaline developer, and information X relating to the carbonate salt concentration of the alkaline developer, the concentration control unit 92 controls the valves V1 to V4. The concentration of the alkali developing component, the dissolved resist, and the carbonate salt in the adjustment tank 5 is maintained within a predetermined range.

  Then, the effect of this embodiment is demonstrated. When the alkali developer comes into contact with air, carbon dioxide in the air is absorbed, and carbonate salts of alkali developing components are generated and accumulated in the alkali developer. This is particularly noticeable when the alkaline developer is recycled for a long time. Here, even if a part of the alkali developing component becomes a carbonate salt, the concentration control unit 92 sets the concentration of the alkali developing component that is not a carbonate salt within a predetermined range based on the information β related to the conductivity. Control. However, it has been found that the development performance of the alkaline developer deteriorates when the concentration of the carbonate salt of the alkali developing component increases. Therefore, it is necessary not only to maintain the concentration of the alkali developing component that is not a carbonate salt within a predetermined range, but also to control the concentration of the carbonate salt in the alkali developer to a specified value or less. Further, the manner of increasing or decreasing the carbonate salt in the alkali developer over time is greatly influenced by various requirements such as the development load, the circulation amount, the air temperature, and the exhaust amount, so that it is difficult to predict. Conventionally, it has been difficult to determine the concentration of carbonate salts quickly, simply and with high accuracy.

  However, according to the present embodiment, the carbonate concentration measuring device 99 having the data acquisition unit 91 and the carbonate salt concentration acquisition unit 94 allows the carbonate salt concentration in the alkali developer to be quickly, easily and highly accurately. Can be measured indirectly. Further, the time required for the measurement can be, for example, within about 10 seconds, and so-called online measurement or real-time measurement is possible.

  Therefore, even when the alkaline developer is recycled, the carbonate salt concentration of the alkaline developer can be appropriately managed, and the development performance can be easily maintained within a suitable range.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, the development processing apparatus is not limited to a liquid crystal panel manufacturing facility, and various developing apparatuses can be used, for example, a semiconductor manufacturing apparatus.

  Moreover, if the alkali developing component of the alkali developer is also alkali, it is not limited to TMAH, and TEAH (tetraethylammonium hydroxide) can be used.

  In the following examples, an aqueous TMAH solution was used as an alkaline developer, and a novolak resin / diazonaphthoquinone positive type resin was used as a resist.

  First, it was confirmed that the refractive index of the alkali developer correlates with the total amount of alkali developer components, dissolved resist, and carbonates in the alkali developer.

  FIG. 2 shows resist development in which the concentration of carbonic acid salts is changed by changing the amount of carbon dioxide dissolved in a resist developer having a TMAH concentration of 2.380% by mass and containing no dissolved resist. It is the graph which adjusted the liquid and plotted the density | concentration and refractive index of carbonate salt. As a refractometer, RA-520N manufactured by Kyoto Electronics was used. The refractive index was almost proportional to the concentration of carbonate salts.

  FIG. 3 shows a resist developer in which the concentration of dissolved resist is changed by changing the amount of resist to be dissolved in a resist developer having a TMAH concentration of 2.380% by mass and not containing carbonate salts. Is a graph plotting the concentration and refractive index of the dissolved resist. On the horizontal axis, the absorbance of the alkaline developer is used instead of the dissolved resist concentration itself. As will be described later, the absorbance and the dissolved resist concentration are in a substantially proportional relationship. The refractive index was almost proportional to the dissolved resist concentration.

  FIG. 4 is a graph plotting the TMAH concentration and the refractive index when the concentration of TMAH, which is an alkali developing component, is changed for an alkaline developer containing no dissolved resist and carbonate salts. The refractive index was almost proportional to the concentration of TMAH.

  As can be seen from these graphs, the refractive index was positively correlated with the increase of the three components, and it was found that the higher the concentration of each component, the higher the refractive index.

  Although not shown, it is a well-known fact that the concentration of the alkali developing component in the alkali developer is substantially proportional to the electrical conductivity.

  Similarly, it is a well-known fact that the dissolved resist concentration in the alkali developer is substantially proportional to the absorbance.

  Subsequently, in the actual developer supply apparatus 100 as shown in FIG. 1, the alkali developer is recycled while developing the resist for 130 minutes, and the measured value by titration of the carbonate salt concentration in the alkali developer. FIG. 5 shows the estimated value of the carbonate salt concentration obtained by calculation using the equation (1) and the difference between the estimated values by ◆, □, and Δ, respectively. In addition, in the vicinity of 0.09 hr and 0.13 hr, the carbonate salt concentration in the alkaline developer is lowered due to partial replacement of the solution, but in other cases, the carbonate type is taken in by the incorporation of carbon dioxide in the air. The salt concentration increased at a nearly constant value. On the other hand, the estimated value shows very good agreement with the actually measured value. The error was about 0.01%. In this example,

  Note that the parameters of the formula (1) are determined in advance in the developer supply apparatus 100 by measuring the carbonate salt concentration by titration of samples obtained at various times, the refractive index, the conductivity, and the absorbance. About 80 data combinations are obtained, and constants A, B, C, and D in equation (1) are obtained by a known fitting method.

  Further, FIG. 6 is a plot of the data in FIG. 5 plotted with ▪ marks as measured values by titration on the horizontal axis and measured values by calculation on the left vertical axis. The difference with respect to the actual measurement value is plotted on the right vertical axis as Δ.

In addition, when the ■ mark was linearly regressed, the straight line indicated by A in the figure was y = 1.0363x−0.0116 and the coefficient of determination R ² = 0.9999, indicating a very high correlation. A graph of y = x in the case of complete correlation is indicated by R in the figure.

  Further, a histogram of difference values is shown in FIG. The difference also showed a normal distribution and was confirmed to be highly accurate.

  DESCRIPTION OF SYMBOLS 9 ... Alkali developer management system, 91 ... Data acquisition part, 94 ... Carbonic acid salt density | concentration acquisition part, 99 ... Carbonic acid salt density | concentration measuring apparatus, 100 ... Developer supply apparatus.

Claims (4)

A data acquisition unit for acquiring information on the refractive index of the alkali developer, information on the conductivity of the alkali developer, and information on the absorbance of the alkali developer;
Based on the information on the refractive index, the information on the conductivity, and the information on the absorbance, a carbonate-based salt concentration acquisition unit that acquires information on the concentration of carbonate-based salts in the alkali developer,
A carbonate-based salt concentration measuring device. The carbonate salt concentration acquisition unit
When the information about the refractive index is α, the information about the conductivity is β, and the information about the absorbance is γ,
The carbonic acid salt concentration measuring apparatus according to claim 1, wherein information relating to the carbonic acid salt concentration is acquired based on Aα−Bβ−Cγ + D.
Here, A, B, and C are positive constants, and D is a constant.
It is. A carbonate-based salt concentration measuring device according to claim 1 or 2,
A control unit for controlling the carbonate salt concentration in the alkaline developer based on the carbonate salt concentration obtained by the carbonate salt concentration measuring device;
Alkali developer management system. Obtaining information on the refractive index of the alkali developer, information on the conductivity of the alkali developer, and information on the absorbance of the alkali developer, and
Obtaining information on the concentration of carbonate salts in the alkali developer based on the information on the refractive index, the information on the conductivity, and the information on the absorbance;
A carbonate-based salt concentration measurement method comprising:

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