JP2020031182A - Measuring instrument, etching system, silicon concentration measuring method, and silicon concentration measuring program - Google Patents

Abstract

To provide a measuring instrument, etching system, silicon concentration measuring method, and silicon concentration measuring program capable of measuring a concentration of a very small amount of silicon in liquid.SOLUTION: According to an embodiment, there is provided a measuring instrument including an input/output unit 10, a memory 13, and a processor 11. To the input/output unit 10 is input measurement value information 17 representing a concentration of each of phosphoric acid, second acid, and water of measurement target liquid including the phosphoric acid, second acid, and water, the second acid having an acid dissociation index pK smaller than a first acid dissociation index pKof the phosphoric acid. The memory 13 stores variation value information 15 including relation between a reference silicon concentration and concentration variations of the phosphoric acid, second acid, and water in adding silicon to reference liquid containing the phosphoric acid, second acid, and water so as to obtain the reference silicon concentration. The processor 11 obtains a silicon concentration of the measurement target liquid corresponding to the measurement value information 17 on the basis of the measurement value information 17 input to the input/output unit 10 and the variation value information 15 read out from the memory.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to a measuring instrument, an etching system, a silicon concentration measuring method, and a silicon concentration measuring program.

  To determine the concentration of silicon contained in the liquid (particularly in the phosphoric acid liquid), (1) off-line analysis (ICP emission spectroscopy), (2) a method of calculating from the amount of dissolved silicon compound and the liquid weight, etc. There is.

  The method (1) requires a long time for analysis, and cannot grasp a silicon concentration that fluctuates in real time. The value obtained by the method (2) is a calculated value, not an actual measurement.

JP-A-5-346402 JP-A-63-226932 JP 2015-195306 A

JM Tour et al., "Evans_pKa_Table", [online], April 5, 2011, ACS Nano, [searched March 10, 2017], Internet <URL: http: // evans.rc.fas.harvard. edu / pdf / evans_pKa_table.pdf>

  An object of the present invention is to provide a measuring device, an etching system, a silicon concentration measuring method, and a silicon concentration measuring program capable of measuring a trace amount of silicon concentration in a liquid.

According to the embodiment, a measuring instrument including an input / output unit, a memory, and a processor is provided. The input / output unit is configured to control the concentration of the phosphoric acid, the second acid, and the water in the liquid to be measured including the second acid and the water having the acid dissociation index pK smaller than the first acid dissociation index pK _a1 of the phosphoric acid and the phosphoric acid Is input. The memory is configured such that a change in the concentration of phosphoric acid, the second acid, and water when silicon is added to a reference solution containing phosphoric acid, a second acid, and water so as to have a reference silicon concentration, The variable value information including the relationship is held. The processor obtains the silicon concentration of the liquid to be measured corresponding to the measurement value information based on the measurement value information input to the input / output unit and the fluctuation value information read from the memory.

According to another embodiment, there is provided an etching system including a first container, a second container, a third container, a fourth container, a measurement unit, and a control unit. The first container is for etching a silicon compound with an etchant containing phosphoric acid and water. The second container is for introducing phosphoric acid into the first container. The third container is for introducing water into the first container. The fourth container is for obtaining an etching solution from the first container and for storing a measurement target solution in which sulfuric acid is added to the etching solution. The measuring unit includes the measuring device of the embodiment, and measures the concentration of silicon contained in the liquid to be measured in the fourth container by the measuring device. The control unit introduces phosphoric acid from the second container into the first container and / or introduces water from the third container into the first container according to the measurement result in the measurement unit.
According to still another embodiment, a measurement object including a second acid and water having an acid dissociation index pK smaller than the first acid dissociation index pK _{a1 of} phosphoric acid and phosphoric acid from a near infrared light spectrometer. Receiving measurement information indicating the concentration of phosphoric acid, second acid, and water in the liquid;
From the memory, the change in the concentration of phosphoric acid, the second acid, and water when silicon is added to the reference solution containing phosphoric acid, the second acid, and water so as to have the reference silicon concentration, and the reference silicon concentration Reading the fluctuation value information including the relationship;
A method for measuring the concentration of silicon contained in the liquid to be measured corresponding to the received measurement value information based on the read variation value information.

According to still another embodiment, the silicon concentration of a liquid to be measured including water and a second acid having an acid dissociation index pK smaller than the first acid dissociation index pK _{a1 of} phosphoric acid and phosphoric acid is measured. For measuring silicon concentration is provided. The silicon concentration measurement program is executed by the processor to provide the processor with a second acid and water having an acid dissociation index pK smaller than the first acid dissociation index pK _{a1 of} phosphoric acid and phosphoric acid. Receiving measurement value information indicating the concentrations of the phosphoric acid, the second acid, and the water in the target liquid,
From the memory, the change in the concentration of phosphoric acid, the second acid, and water when silicon is added to the reference solution containing phosphoric acid, the second acid, and water so as to have the reference silicon concentration, and the reference silicon concentration Read the variable value information including the relationship,
Based on the read variation value information, the concentration of silicon contained in the measurement target liquid corresponding to the received measurement value information is calculated.

FIG. 2 is a block diagram of a measuring device according to the embodiment. 4 is a graph showing a relationship among a phosphoric acid concentration, a sulfuric acid concentration, and a silicon concentration for first concentrations 1 and 2; 7 is a graph showing a relationship among a phosphoric acid concentration, a sulfuric acid concentration, and a silicon concentration for first concentrations 3 to 5. The graph which shows the relationship between the phosphoric acid concentration, the sulfuric acid concentration, and the silicon concentration about the 1st concentration 6-8. The graph which shows the relationship between the phosphoric acid concentration, the sulfuric acid concentration, and the silicon concentration about 1st concentration 9-10. FIG. 2 is a functional block diagram of a processor included in the measuring device of FIG. 1. 5 is a flowchart illustrating a flow of an operation of the measuring device according to the embodiment. FIG. 1 is a block diagram illustrating an example of an etching system according to an embodiment. FIG. 9 is a conceptual diagram of a near-infrared light spectrometer in the etching system of FIG. 8. 9 is a flowchart showing the flow of silicon concentration management in the etching system of FIG. 9 is a flowchart showing the flow of phosphoric acid concentration management in the etching system of FIG. FIG. 2 is a block diagram showing another example of the etching system of the embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

[First Embodiment]
A measuring instrument, a silicon concentration measuring method and a silicon concentration measuring program will be described.

The measuring device is for measuring the silicon concentration in the liquid to be measured including the second acid and water having an acid dissociation index pK smaller than the first acid dissociation index pK _{a1 of} phosphoric acid and phosphoric acid. . The liquid to be measured may be a mixed liquid containing phosphoric acid, a second acid, and water.

  Examples of the second acid include an acid having an acid dissociation index pK of less than 2.12, and it is preferable to use an acid of 1.8 or less. There is no particular lower limit for the acid dissociation index pK, but according to one example, it is -15 or more.

As the second acid, for example, sulfuric acid, hydrochloric acid, nitric acid, trifluorosulfonic acid or a mixture thereof can be used. In water at a temperature of 25 ° C., the first acid dissociation index pK _a1 of sulfuric acid is −3.0, the second acid dissociation index pK _a2 of sulfuric acid is 1.99, and the acid dissociation index of hydrochloric acid is 1.99. The pK is -8.0, the acid dissociation index pK of nitric acid is -1.3, and the acid dissociation index pK of trifluorosulfonic acid is -15.0. In addition, as these acid dissociation indexes, the values described on page 1 of Non-Patent Document 1 are described.

Hereinafter, the measuring device of the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration example of the measuring device according to the first embodiment.
1. Configuration of Measuring Device The measuring device 1 is, for example, a general-purpose personal computer or a dedicated densitometer incorporating a computer. Alternatively, a server that receives data from a plurality of measurement targets may be used. Then, the measuring instrument 1 measures the silicon concentration in the liquid to be measured including phosphoric acid, the second acid, water and silicon. An example in which a mixed solution containing, for example, phosphoric acid, sulfuric acid as a second acid, silicon, and water is used as the measurement target liquid will be described below. 1, the measuring instrument 1 includes an input / output circuit 10 as an input / output unit, a processor 11, a ROM 12, a RAM 13, and a display 14.

  The input / output circuit 10 controls transmission and reception of information between the measuring instrument 1 and the outside. For example, in this example, when the silicon concentration is measured by the measuring device 1, the input / output circuit 10 is connected to the near-infrared light spectrometer by wire or wirelessly, and receives various data. The input / output circuit 10 receives, for example, a data input from a user or a command to start measurement. The ROM 12 holds programs executed by the processor 11 and necessary data. The RAM 13 functions as a work area of the processor 11 and holds various data. The RAM 13 stores, for example, fluctuation value information 15, initial value data (initial value information) 16, measured value data (measured value information) 17, and a silicon concentration measurement program 18. The processor 11 is, for example, a CPU or the like. The processor 11 executes the silicon concentration measurement program 18 stored in the RAM 13 and stores the fluctuation value information 15, the initial value data (initial value information) 16 and the measurement value data (measurement value information) 17. Then, the silicon concentration in the liquid to be measured is calculated. Then, the display 14 displays the silicon concentration calculated by the processor 11.

  Next, data held in the RAM 13 and details of the processor 11 will be described. First, details of data held in the RAM 13 will be described.

  The initial value data 16 and the measurement value data 17 are concentration information on the liquid to be measured, which is the actual measurement target.

  The measurement value data 17 is measurement value information including a phosphoric acid concentration (wt%), a sulfuric acid concentration (wt%), and a water concentration (wt%) of the liquid to be measured by near infrared light spectroscopy. These values are input to the input / output circuit 10 at the time of measurement.

  The initial value data 16 is obtained before the measurement value data 17 is measured, and the phosphoric acid concentration (wt%), the sulfuric acid concentration (wt%), and the water concentration (wt%) in a state before the liquid to be measured contains silicon. wt%). That is, the initial value data 16 can be said to be the initial values of the phosphoric acid concentration, the sulfuric acid concentration, and the water concentration of the liquid to be measured. The initial value data 16 is given to the input / output circuit 10 before the silicon is mixed with the liquid to be measured. The initial value data 16 may be an actually measured value by near-infrared light spectroscopy or the like, or may be obtained by calculation such as simulation. The initial value data 16 can be used as a control value or a target value of the concentration of the liquid to be measured. An example of the use of the liquid to be measured is an etchant for an etching process.

  The fluctuation value information 15 is not the concentration information of the measurement target liquid itself but information of the first reference liquid and the second reference liquid used for determining the silicon concentration of the measurement target liquid. The second reference liquid is a mixed liquid containing phosphoric acid, sulfuric acid as the second acid, and water, and not containing silicon. Specifically, the fluctuation value information 15 includes the first concentration of phosphoric acid, sulfuric acid, and water in the first reference solution in which silicon is added to the second reference solution so as to have the reference silicon concentration, and the second concentration in which silicon is not added. 4 shows the relationship between the second concentration of phosphoric acid, sulfuric acid, and water in the reference liquid and the reference silicon concentration. The variation value information 15 includes a plurality of patterns of a correspondence relationship among the first concentration, the second concentration, and the reference silicon concentration. The first density and the second density are obtained, for example, by near-infrared light spectroscopy measurement. The fluctuation value information 15 is provided from the near-infrared light spectrometer before the measurement of the silicon concentration of the liquid to be measured. Table 1 is an example illustrating the concept of the second density.

  Table 1 shows an example of the second concentration of phosphoric acid, sulfuric acid, and water in the second reference solution measured by near infrared spectroscopy. As shown in Table 1, the second concentration, specifically, the concentration (wt%) of phosphoric acid, sulfuric acid, and water measured by near-infrared light spectroscopy of the second reference solution is plural (4 in Table 1). Type) pattern. The number of patterns of the second concentration is not limited to four, but can be adjusted according to the use of the liquid to be measured, and can be one or two or more.

  The first concentration is the concentration (wt%) of phosphoric acid, sulfuric acid, and water of the first reference solution obtained by mixing silicon with the second reference solution satisfying the second concentration at the reference silicon concentration, as measured by near infrared spectroscopy. It is. When silicon is added to the second reference solution, the concentrations of phosphoric acid, sulfuric acid, and water fluctuate from the second concentration. The fluctuation width changes under the influence of the added concentration of silicon. Table 2 and FIGS. 2 to 5 are examples showing the concept of the relationship between the first concentration and the reference silicon concentration. First concentration (wt%) of phosphoric acid, sulfuric acid, and water measured by near infrared spectroscopy when silicon is mixed at 50 ppm and 150 ppm with a plurality of second reference solutions having a second concentration 1 shown in Table 1. Corresponds to the first concentration 1-2. The first concentrations 3 to 5 correspond to the concentrations of phosphoric acid, sulfuric acid, and water measured by near-infrared light spectroscopy when silicon is mixed with 50 ppm, 70 ppm, and 150 ppm in a plurality of second reference solutions having the second concentration 2. 1 concentration (wt%). Further, the first concentrations 6 to 8 are obtained by mixing phosphoric acid, sulfuric acid, and water by near infrared spectroscopy when silicon is mixed with 50 ppm, 70 ppm, and 150 ppm in a plurality of second reference solutions having the second concentration 3. Is the first concentration (wt%). Further, the first concentrations 9 to 10 correspond to the first concentrations of phosphoric acid, sulfuric acid, and water measured by near infrared spectroscopy when silicon is mixed with 50 ppm and 150 ppm in a plurality of second reference solutions having the second concentration. Concentration (wt%).

  FIG. 2 shows the relationship between the concentration of phosphoric acid (wt%) and the concentration of sulfuric acid (wt%) of the first and second concentrations 1-2, and the concentration of Si (ppm).

  FIG. 3 shows the relationship between the phosphoric acid concentration (wt%) and the sulfuric acid concentration (wt%) of the first concentrations 3 to 5, and the Si concentration (ppm).

  FIG. 4 shows the relationship between the phosphoric acid concentration (wt%) and the sulfuric acid concentration (wt%) among the first concentrations 6 to 8, and the Si concentration (ppm).

  FIG. 5 shows the relationship between the phosphoric acid concentration (wt%) and the sulfuric acid concentration (wt%) of the first concentrations 9 to 10, and the Si concentration (ppm).

  That is, as shown in FIGS. 2 to 5, when silicon is added to the second reference liquid, the ratio of phosphoric acid, sulfuric acid, and water changes. Various patterns exist for the degree of this variation. The variation value information 15 can be said to be information indicating a plurality of patterns on how to change the ratio. The examples of Tables 1 and 2 and FIGS. 2 to 5 show cases of two or three patterns, but one pattern or four or more patterns of information may be held. Further, the fluctuation value information 15 may be obtained by calculation such as simulation instead of being obtained by measurement by near-infrared light spectroscopy as described above.

  Next, details of the processor 11 will be described. The processor 11 performs the function of calculating the silicon concentration in the liquid to be measured mixed with silicon by executing the silicon concentration measurement program. FIG. 6 is a functional block diagram of the processor 11 when the silicon concentration measurement program 18 is executed.

  As illustrated in FIG. 6, the processor 11 executes the silicon concentration measurement program 18, and thereby executes an initial value data acquisition unit 20, a measurement value data acquisition unit 21, a first comparison unit 22, a first selection unit 23, It functions as one concentration group determination unit 24, second comparison unit 25, second selection unit 26, and silicon concentration determination unit 27.

The initial value data acquisition unit 20 acquires the initial value data 16 through the input / output circuit 10. The measurement value data acquisition unit 21 acquires the measurement value data 17 from the near-infrared light spectroscope. The first comparing unit 22 compares the second density described with reference to Table 1 as an example and the acquired initial value data 16. The first selector 23 selects one of the second densities illustrated in Table 1 based on the comparison result in the first comparator 22. The first density group determination unit 24 determines a first density group corresponding to the selected second density from among the plurality of first densities described with reference to Table 2 as an example. The second comparison unit 25 compares the determined first density group with the acquired measurement value data 17. The second selector 26 selects one of the first densities from the group of the first densities based on the comparison result of the second comparing unit 25. The silicon concentration determination unit 27 determines the silicon concentration in the liquid to be measured based on the first concentration selected by the second selection unit 26. Then, the determined silicon concentration is displayed on the display 14.
2. Next, the operation of the measuring device according to the embodiment will be described.

  First, the flow of the entire operation will be described with reference to FIG. FIG. 7 is a flowchart showing the entire flow of the operation of the measuring instrument. FIG. 7 illustrates an example in which the measurement target liquid is an aqueous solution containing phosphoric acid and sulfuric acid. First, the initial value data acquisition unit 20 of the processor 11 receives the second concentration consisting of the phosphoric acid concentration, the sulfuric acid concentration, and the water concentration of the liquid to be measured in a state before the silicon mixing in the input / output circuit 10 and receives the initial value data. 16 is stored in the RAM 13 (step S1). The variation value information 15 may be stored in the RAM 13 in advance before step S1, or may be stored in the RAM 13 after step S1.

  Then, after mixing silicon into the liquid to be measured, the concentration of phosphoric acid, sulfuric acid and water in the liquid to be measured is measured by a near-infrared light spectrometer to obtain an absorption spectrum.

  Then, for example, when the input / output circuit 10 of the measuring device 1 receives the measurement instruction of the silicon concentration in the liquid to be measured (Step S2), the measurement value data acquisition unit 21 of the processor 11 makes the measurement of the liquid to be measured after the silicon mixing. The first concentration including the phosphoric acid concentration, the sulfuric acid concentration, and the water concentration is received by the input / output circuit 10 and stored in the RAM 13 as the measurement value data 17 (step S3).

  Next, the first comparing unit 22 of the processor 11 compares the initial value data 16 obtained in step S <b> 1 with the second density of the fluctuation value information 15 stored in the RAM 13. Specifically, the first comparison unit 22 includes the second concentrations 1 to 4 illustrated in Table 1 as the second concentration, and the phosphoric acid of the liquid to be measured in the state before the silicon mixing, which is the initial value data 16, Compare the concentrations of sulfuric acid and water. Then, the first selection unit 23 selects the closest (or the same) second density as a result of the comparison in the first comparison unit 22 (step S4). It is assumed that, for example, the second density 1 is selected by the first selecting unit 23.

  Next, the first density group determination unit 24 determines a first density group corresponding to the selected second density 1 from the fluctuation value information 15 held in the RAM 13 (step S5). In the case of Table 2, the first density group corresponding to the second density 1 corresponds to the first density 1 and the first density 2.

  The second comparing unit 25 compares the measured value data 17 obtained in step S3 with the first density 1 and the first density 2 obtained in step S5. Then, the second selecting unit 26 selects the closest (or the same) first density as a result of the comparison in the second comparing unit 25 (Step S6). It is assumed that, of the first density 1 and the first density 2, the first density selected in step S6 is the first density 1. As shown in Table 2, the first concentration 1 corresponds to the concentration of phosphoric acid, the concentration of sulfuric acid and the concentration of sulfuric acid in the first reference solution in which silicon is added to the second reference solution satisfying the second concentration 1 so that the concentration thereof is 50 ppm. Corresponds to water concentration. The measured value data 17 of the liquid to be measured is the same as or closest to the first concentration 1. Accordingly, the silicon concentration determining unit 27 determines that the silicon concentration of the liquid to be measured is 50 ppm (Step S7).

  The second comparing unit 25 and the second selecting unit 26 may calculate the silicon concentration by, for example, linear approximation. That is, the silicon concentrations shown in Table 2 have discrete values. However, as shown in the graphs indicated by the broken lines and the solid lines in FIGS. 2 to 5, it is also possible to obtain these discrete values by linear approximation.

For example, it is assumed that the initial value data 16 obtained in step S1 is the second density 2, and the measured value data 17 obtained in step S3 is as follows.
-Phosphoric acid concentration: 85.41 wt%
・ Sulfuric acid concentration: 1.53wt%
-Water concentration: 13.06 wt%
Then, these values match the linear approximation shown in FIG. The value of each concentration is approximately halfway between the value when the silicon concentration is 70 [ppm] and the value when the silicon concentration is 150 [ppm]. Therefore, the silicon concentration in this case can be estimated to be about 110 [ppm]. These calculations may be performed by any of the second comparing unit 25, the second selecting unit 26, and the silicon concentration determining unit 27.

  Through the above steps, the silicon concentration of the measurement target liquid containing phosphoric acid, sulfuric acid as the second acid, and water is measured. Therefore, according to the measuring device of the embodiment, the silicon concentration in the liquid to be measured is determined from the concentration changes of the phosphoric acid and the second acid before and after mixing the silicon in the liquid to be measured containing phosphoric acid, the second acid, and water. Can be obtained. Therefore, the measuring device of the embodiment can measure a very small silicon concentration of an unavoidable impurity level. Such a trace amount of silicon concentration cannot be measured by any of a specific gravity measuring method such as near infrared light spectroscopy, a molybdenum yellow absorption spectroscopy method, and an electric conductivity measuring method. This is because, in the case of the specific gravity measurement method, a change in specific gravity cannot be detected because the concentration of silicon mixed into the liquid to be measured is too low. Further, in the case of the molybdenum yellow absorption spectrophotometer, the silicon concentration cannot be measured because the absorption derived from silicon overlaps with the absorption derived from phosphoric acid and cannot be separated.

  Further, according to the measuring instrument of the embodiment, the time required for the measurement can be shortened, so that it is possible to grasp the silicon concentration that fluctuates in real time due to the etching process or the like.

  Note that the measuring device according to the embodiment may further include a near-infrared light spectrometer. The near-infrared light spectrometer can accurately and easily measure the concentrations of phosphoric acid, sulfuric acid, and water in the liquid to be measured from the absorption spectrum, so that the silicon concentration in the liquid to be measured can be obtained with high precision. .

  Instead of using the measured values as the reference silicon concentration, the processor 11 uses the processor 11 to measure the concentrations of phosphoric acid, sulfuric acid, and water in the liquid to be measured before mixing silicon, and the concentrations of phosphoric acid, sulfuric acid, and water in the liquid to be measured after mixing silicon. The silicon concentration of the liquid to be measured after mixing the silicon may be calculated based on the concentration of the silicon, and the calculated value may be used as the reference silicon concentration.

[Second embodiment]
The etching system will be described. The etching system is a system for etching a silicon compound with an etching solution containing phosphoric acid and water. The silicon compound can be, for example, a silicon compound film formed on a substrate. Examples of the substrate include a SiC substrate, a GaN substrate, and the like. An etching system according to the embodiment will be described with reference to FIG.
1. Configuration of Etching System The etching system shown in FIG. 8 is used to etch a silicon compound with an etching solution containing phosphoric acid and water, and to introduce phosphoric acid into the first container 31. A second container (phosphoric acid supply unit) 32, a third container (water supply unit) 33 for introducing water into the first container 31, a near-infrared light spectroscope 34, and a sample liquid (liquid to be measured). ) Is provided with a measuring unit 35 for measuring the silicon concentration included in (1) and a control unit 36. The near-infrared light spectrometer 34 includes a fourth container (not shown in FIG. 8) for acquiring an etching solution from the first container 31 and for storing a sample solution in which sulfuric acid is added to the etching solution. FIG. 9 shows an example of the fourth container. The measuring device according to the first embodiment is used for the measuring unit 35. The control unit 36 controls the entire etching system. Further, the control unit 36 introduces the phosphoric acid in the second container 32 into the first container 31 and / or transfers the water in the third container 33 to the first container 31 according to the measurement result in the measuring unit 35. Introduce. In FIG. 8, for convenience of illustration, it appears that the control unit 36 is electrically connected only to the first container 31 and the second container 32, but is electrically connected to each unit configuring the etching system. Thus, signals can be exchanged between the control unit 36 and each unit.

  A buffer tank 37 and a replenishing tank 38 are arranged in a path from the second container 32 and the third container 33 to the first container 31. The second container 32 and the third container 33 are connected to a buffer tank 37 via a first pipe 39 and a second pipe 40, respectively. The buffer tank 37 is connected to a replenishing tank 38 via a third pipe 41. The flow meter 42 and the valve 43 are provided in this order from the upstream side of the third pipe 41. The concentration meter 44 is connected to the replenishment tank 38 via a fourth pipe 45.

  The first container 31 contains an etching liquid 46 containing phosphoric acid and water. The silicon compound 47 is immersed in the etching solution 46, and the silicon compound 47 is etched. The etching solution 46 overflowing from the first container 31 during the etching process or the like is temporarily stored in a storage tank 48. The storage tank 48 is connected to the replenishment tank 38 via a fifth pipe 49. The fifth pipe 49 is provided with a filter (not shown). The filter removes foreign substances contained in the etching solution. The etchant 46 overflowing from the first container 31 during the etching process is collected in the storage tank 48, passes through the filter from the storage tank 48, passes through the fifth pipe 49, and is stored in the replenishment tank 38. . The storage tank 48 is also connected to a drain pipe 50. The replenishment tank 38 is connected to the first container 31 via a sixth pipe 51. The pump 52 and the heater 53 are provided in this order from the upstream side of the sixth pipe 51. Here, a system including a path from the replenishment tank 38 to the first container (etching processing unit) 31 and a path from the first container 31 to the replenishment tank 38 via the storage tank 48 is referred to as an etching system. The etching system includes, in addition to the first container 31, the replenishment tank 38, and the storage tank 48, piping in the above-described path.

  The inside of the etching treatment system is filled with an etching solution 46 containing phosphoric acid and water. In the etching treatment, the volume of the etching solution 46 decreases due to the evaporation of water and the phosphoric acid concentration increases, or the phosphoric acid concentration decreases due to consumption of phosphoric acid. Need to be managed. The concentration of phosphoric acid in the etching solution 46 of the etching system is measured by the densitometer 44, and a signal is transmitted to the control unit 36 when the concentration is out of the management value. When the controller 36 receives this signal, it adjusts the amount of phosphoric acid supplied from the second container 32 to the buffer tank 37 and the amount of water supplied from the third container 33 to the buffer tank 37, and as a replenisher, a predetermined concentration of water is supplied. Prepare phosphoric acid water. The replenisher in the buffer tank 37 is supplied to the etching system while opening the valve 43 and adjusting the supply amount with the flow meter 42. By controlling the phosphoric acid concentration of the replenisher and the supply amount of the replenisher from the buffer tank 37 to the etching system, the phosphoric acid concentration of the etching solution 46 in the etching system can be set within the control value. To increase the concentration of phosphoric acid in the etching solution 46, the concentration of phosphoric acid in the replenisher may be increased, or the supply amount of the replenisher from the buffer tank 37 to the etching system may be reduced. On the other hand, in order to lower the concentration of phosphoric acid in the etching solution 46, the concentration of phosphoric acid in the replenisher may be reduced, or the supply amount of the replenisher from the buffer tank 37 to the etching system may be increased. The supply amount of the replenisher from the buffer tank 37 to the etching system can be adjusted by monitoring the supply amount with the flow meter 42 and adjusting the opening amount of the valve 43.

  When the management values of the phosphoric acid concentration and the water concentration are changed by changing the etching conditions such as the phosphoric acid concentration, the water concentration, and the temperature of the etching solution 46, a signal is transmitted to the control unit 36, and the control unit 36 The management values of the phosphoric acid concentration and the water concentration of the liquid 46 are reset to set new management values.

  The etching system may include a water supply tank for supplying the evaporated water to the first container 31 separately from the third container 33.

  Further, the etching system can be provided with a densitometer for directly measuring the phosphoric acid concentration of the etching solution 46 in the first container 31 instead of the densitometer 44 or separately from the densitometer 44.

  FIG. 9 is a schematic block diagram of the near-infrared light spectroscope 34. As illustrated, the near-infrared light spectroscope 34 includes a test container 60 as a fourth container, a light source 61, a spectroscope 62, a calculator 63, and a temperature controller 64.

  The test container 60 is, for example, a container that is transparent to near-infrared light. The test container 60 is supplied with the etching liquid 46 from the first container 31 for etching the silicon compound, and sulfuric acid from a sulfuric acid supply unit different from the first container 31. As a result, in the test container 60, a sample liquid obtained by adding sulfuric acid to the etching liquid 46 in which silicon is dissolved is purified as a liquid to be measured. The supply rate and supply timing of the etching liquid 46 and sulfuric acid are controlled by, for example, the control unit 36. The temperature of the sample liquid (liquid to be measured) in the test container 60 is controlled by the temperature controller 64. It is desirable that the temperature of the sample liquid is controlled to be equal to or lower than room temperature in order to increase the measurement accuracy by near-infrared light spectroscopy.

  The light source 61 generates near-infrared light, and the generated near-infrared light passes through the test container 60.

  The spectroscope 62 splits the near-infrared light that has passed through the test container 60, and obtains an absorption spectrum by the sample liquid (liquid to be measured).

The computing unit 63 calculates the concentration of phosphoric acid, the concentration of sulfuric acid, and the concentration of water in the sample liquid (liquid to be measured) based on the absorption spectrum obtained by the spectroscope 62, and outputs the result to the measuring unit 35. That is, the initial value data 16 and the measured value data 17 described in FIG. 1 of the first embodiment are provided from the computing unit 63 to the measuring unit 35. Further, the second density and the first density can also be generated based on information from the calculator 63.
2. Operation of Etching System The operation of the etching system will be described with reference to FIGS. FIG. 10 is a flowchart showing a flow of silicon concentration management in the etching system. On the other hand, FIG. 11 is a flowchart showing the phosphoric acid concentration management in the etching system.

About phosphoric acid concentration management Initial values of the phosphoric acid concentration, the sulfuric acid concentration, and the water concentration of the etching solution 46 of the etching treatment system are input to the measuring unit 35. The initial phosphoric acid concentration and water concentration are suitable for predetermined etching processing conditions, and are measured by, for example, the densitometer 44. The etching solution 46 used for the etching process in the system shown in FIG. 8 is a phosphoric acid aqueous solution and does not contain sulfuric acid. Sulfuric acid is added to the sample liquid used for the measurement of the near-infrared light spectrometer 34 in order to increase the accuracy of the silicon concentration measurement. The sulfuric acid concentration suitable for measuring the silicon concentration can vary depending on the phosphoric acid concentration and the water concentration. Therefore, the initial value of the etching liquid 46 includes the sulfuric acid concentration corresponding to these concentrations in addition to the phosphoric acid concentration and the water concentration. The input initial value is held in the RAM 13 as initial value data 16. The measuring unit 35 calculates the ratio of phosphoric acid to water based on the initial values of the phosphoric acid concentration and the water concentration, and transmits the calculated ratio to the control unit 36 as a management value (step S20).

  The etching system is filled with the etching liquid 46 whose ratio of phosphoric acid and water is within the control value (step S21). The ratio of phosphoric acid to water in the etching solution 46 of the etching system is measured by the densitometer 44 (step S22). When the ratio of phosphoric acid and water in the etching solution 46 of the etching system is within the control value (Yes in step S23), the etching process is performed while the measurement by the densitometer 44 is performed at regular intervals.

  If the ratio of phosphoric acid and water in the etching solution 46 of the etching system deviates from the control value (No in step S23), a signal is transmitted to the control unit 36. When the controller 36 receives this signal, it adjusts the amount of phosphoric acid supplied from the second container 32 to the buffer tank 37 and the amount of water supplied from the third container 33 to the buffer tank 37, and as a replenisher, a predetermined concentration of water is supplied. A phosphoric acid solution is prepared (Step S24). The replenisher in the buffer tank 37 is supplied to the etching system while the valve 43 is opened and the supply amount is adjusted by the flow meter 42 (step S25). Production (preparation) and supply of the replenisher are performed until the ratio of phosphoric acid and water in the etching solution 46 of the etching treatment system falls within the control value.

Silicon Concentration Measurement A silicon concentration measurement command is transmitted to the control unit 36 every time a predetermined time elapses from the start of the etching process. The control unit 36 obtains a sample liquid by collecting a part of the etching liquid 46 in the etching processing system into the test container 60 (step S11). As described above, the etching solution 46 does not contain sulfuric acid (No in step S12). Thus, the control unit 36 obtains the liquid to be measured by adding sulfuric acid to the sample liquid so as to have a predetermined concentration (step S13). Subsequently, the near-infrared light spectrometer 34 measures the concentration of phosphoric acid, the concentration of sulfuric acid, and the concentration of water in the liquid to be measured in the test container 60 (step S14). When the obtained measurement result is input to the measurement unit 35, it is stored in the RAM 13 as the measurement value data 17.

  The control unit 36 transmits a signal to the measurement unit 35, and the first comparison unit 22 in the measurement unit 35 compares the second density of the variation value information 15 in the RAM 13 with the initial value data 16. The first comparing unit 22 selects one of the plurality of second densities based on the comparison result. The first density group determination unit 24 in the measurement unit 35 determines a first density group corresponding to the selected second density from the fluctuation value information 15 including the plurality of first densities. The second comparing unit 25 in the measuring unit 35 compares the determined first density group with the acquired measured value data 17. The second selecting unit 26 in the measuring unit 35 selects one of the first densities from the first density group based on the comparison result in the second comparing unit 25. The silicon concentration determination unit 27 in the measurement unit 35 determines the reference silicon concentration corresponding to the first concentration selected by the second selection unit 26 as the silicon concentration in the liquid to be measured. Then, the measurement unit 35 displays the determined silicon concentration on the display 14 (Step S15). The details of the processing in step S15 are as described with reference to FIG. 7 in the first embodiment.

  When the silicon concentration calculated in step S15 deviates from the control value (No in step S16), the control unit 36 transmits a signal to discharge the etching solution 46 in the storage tank 48 to the outside of the system through the drain pipe 50. (Step S17). Further, the control unit 36 adjusts the amount of phosphoric acid supplied from the second container 32 to the buffer tank 37 and the amount of water supplied from the third container 33 to the buffer tank 37, and as a replenisher, a predetermined concentration of phosphoric acid aqueous solution. (Step S18).

  Next, the controller 36 sends a signal to supply the replenisher in the buffer tank 37 to the etching system while opening the valve 43 and adjusting the supply amount with the flow meter 42 (step S19). As a result, the silicon concentration in the etching solution in the etching system is set within the control value.

  Thereafter, the silicon concentration measurement command is transmitted to the control unit 36, and the sampling of the sample liquid (step S11) is performed again.

  According to the above-described etching system, it is possible to measure the concentration of silicon present in a trace amount in the etching solution, so that the silicon concentration that fluctuates due to the etching process can be grasped in real time.

  The etching system is not limited to a system using an etching solution containing no sulfuric acid, and may be a system containing sulfuric acid in the etching solution. One example is shown in FIG. 12 except that the etching system shown in FIG. 12 includes a fifth container 70 for introducing sulfuric acid into the first container 31 and a seventh pipe 71 connecting the fifth container 70 and the buffer tank 37. 8 has the same configuration as the etching system shown in FIG. In the silicon concentration management in the etching system shown in FIG. 12, since the sulfuric acid is contained in the etching liquid 46 in advance, a step of adding sulfuric acid to the sample liquid before the measurement by the near-infrared light spectroscope 34 (step S13). Although it may be omitted, if the sulfuric acid concentration in the sample solution is low, a step of adding sulfuric acid to the sample solution (Step S13) may be performed to set the sulfuric acid concentration in the sample solution to a concentration suitable for measurement. It is possible. When the sulfuric acid concentration in the sample solution is high, a step of adding phosphoric acid and / or water to the sample solution to lower the sulfuric acid concentration is performed.

  In the above embodiment, the case where the function of calculating the silicon concentration is implemented by software has been described as an example. However, it may be implemented by hardware, or may be implemented by a combination of software and hardware. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable storage medium. Such a recording medium is not particularly limited as long as it can be accessed by a computer or a processor. For example, an optical disk such as a RAM, a ROM, an EEPROM (registered trademark) (including a USB memory and a memory card), a CD-ROM, and a magnetic disk such as a hard disk can be used.

  Further, in the above embodiment, the case where the second density (Table 1) and the first density (Table 2) are treated as separate information has been described as an example, but these may be integrated data. That is, as described above, Tables 1 and 2 are for selecting one of the first concentrations contained therein and calculating the silicon concentration based on the selected first concentration and the corresponding reference silicon concentration. It is. Therefore, Table 1 and Table 2 do not need to be separate, and the form is not limited to those described in Tables 1 and 2, and it is sufficient that the first concentration can be selected based on the measurement value data 17. For example, the case where the ratio of phosphoric acid, sulfuric acid, and water when silicon is not included, the silicon concentration, and the amount of change in the ratio of phosphoric acid, sulfuric acid, and water when silicon is dissolved may be held.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

  DESCRIPTION OF SYMBOLS 1 ... Measuring instrument, 10 ... I / O circuit, 11 ... Processor, 12 ... ROM, 13 ... RAM, 14 ... Display, 15 ... Variation value information, 16 ... Initial value data, 17 ... Measured value data, 18 ... Silicon concentration measurement Program, 20: Initial value data acquisition unit, 21: Measurement value data acquisition unit, 22: First comparison unit, 23: First selection unit, 24: First concentration group determination unit, 25: Second comparison unit , 26: second selecting unit, 27: silicon concentration determining unit, 31: first container, 32: second container, 33: third container, 34: near infrared spectrometer, 35: measuring unit, 36 ... Control unit, 37: buffer tank, 38: replenishment tank, 42: flow meter, 43: valve, 44: concentration meter, 46: etching solution, 47: silicon compound, 52: pump, 53: heater, 70: fifth container , 71... Seventh pipe.

Claims (10)

Measurement value information indicating the concentrations of phosphoric acid, second acid, and water in the liquid to be measured containing the second acid and water having an acid dissociation index pK smaller than the first acid dissociation index pK _a1 of phosphoric acid and phosphoric acid An input / output unit to which
A concentration change of the phosphoric acid, the second acid, and the water when silicon is added to a reference liquid containing the phosphoric acid, the second acid, and the water so as to have a reference silicon concentration; A memory for storing fluctuation value information including a relationship with the concentration,
A processor that obtains a silicon concentration of the liquid to be measured corresponding to the measurement value information based on the measurement value information input to the input / output unit and the fluctuation value information read from the memory. Measuring instrument.   The measuring device according to claim 1, wherein the measurement value information is obtained from an absorption spectrum of the liquid to be measured by near-infrared light spectroscopy.   The measuring device according to claim 1, wherein the liquid to be measured is an etching liquid for etching a silicon compound. The input / output unit includes the measurement value information,
Initial value information indicating the concentration of the phosphoric acid, the second acid, and the water in a state where the measurement target liquid does not include silicon is input,
The fluctuation value information includes, as the relationship, the first concentration of the phosphoric acid, the second acid, and the water when the silicon is added to the reference solution so as to have the reference silicon concentration; Including a plurality of types of relationships between the phosphoric acid, the second acid, the second concentration of the water, and the reference silicon concentration before adding the silicon,
The processor compares the density of the initial value information with a plurality of the second densities, selects one of the plurality of the second densities, and calculates the first density corresponding to the selected second density. Selecting and comparing the selected first concentration with the concentration of the measurement value information, and determining the reference silicon concentration corresponding to the first concentration selected based on the result of the comparison, as the silicon concentration of the liquid to be measured. The measuring device according to any one of claims 1 to 3, which determines:   The measuring device according to any one of claims 1 to 4, wherein the second acid is sulfuric acid. A first container for etching a silicon compound with an etching solution containing phosphoric acid and water;
A second container for introducing phosphoric acid into the first container,
A third container for introducing water into the first container;
A fourth container for accommodating the etching solution from the first container and for containing a measurement target solution in which sulfuric acid is added to the etching solution;
A measuring unit comprising the measuring device according to any one of claims 1 to 5, and measuring a silicon concentration contained in the liquid to be measured in the fourth container,
A control unit that introduces the phosphoric acid from the second container into the first container and / or introduces the water from the third container into the first container according to a measurement result in the measurement unit. The etching system. The near-infrared light spectrometer determines that the phosphoric acid and the second acid of the liquid to be measured include a second acid and water having an acid dissociation index pK smaller than the first acid dissociation index pK _{a1 of} phosphoric acid and phosphoric acid. Receiving measurement value information indicating the concentration of the acid and the water,
From the memory, the concentration change of the phosphoric acid, the second acid, and the water when silicon is added to the reference solution containing the phosphoric acid, the second acid, and the water so as to have the reference silicon concentration. Reading variation value information including the relationship with the reference silicon concentration;
Obtaining a concentration of silicon contained in the liquid to be measured corresponding to the received measurement value information, based on the read variation value information. The method further comprises receiving initial value information indicating the concentrations of the phosphoric acid, the second acid, and the water in a state where the liquid to be measured does not contain silicon,
The fluctuation value information includes, as the relationship, the first concentration of the phosphoric acid, the second acid, and the water when the silicon is added to the reference solution so as to have the reference silicon concentration; Including a plurality of types of relationships between the phosphoric acid, the second acid, the second concentration of the water, and the reference silicon concentration before adding the silicon,
Comparing the density of the initial value information with the plurality of second densities, selecting one of the plurality of second densities, selecting the first density corresponding to the selected second density, and selecting Comparing the first concentration and the concentration of the measurement value information, and determining the reference silicon concentration corresponding to the first concentration selected based on the result of the comparison as the silicon concentration of the liquid to be measured. The method for measuring a silicon concentration according to claim 7. A silicon concentration measurement program for measuring the silicon concentration of a liquid to be measured including a second acid and water having an acid dissociation index pK smaller than the first acid dissociation index pK _{a1 of} phosphoric acid and phosphoric acid, When executed by a processor, for the processor:
Measurement value information indicating the concentrations of phosphoric acid, second acid, and water in the liquid to be measured containing the second acid and water having an acid dissociation index pK smaller than the first acid dissociation index pK _a1 of phosphoric acid and phosphoric acid To receive
From the memory, the concentration change of the phosphoric acid, the second acid, and the water when silicon is added to the reference solution containing the phosphoric acid, the second acid, and the water so as to have the reference silicon concentration. Read variation value information including the relationship with the reference silicon concentration,
A silicon concentration measurement program for calculating a concentration of silicon contained in the measurement target liquid corresponding to the received measurement value information based on the read variation value information. For the processor,
The measurement value information and the initial value information indicating the concentration of the phosphoric acid and the second acid and the water in a state where the liquid to be measured does not contain silicon,
The fluctuation value information includes, as the relationship, the first concentration of the phosphoric acid, the second acid, and the water when the silicon is added to the reference solution so as to have the reference silicon concentration; Including a plurality of types of relationships between the phosphoric acid, the second acid, the second concentration of the water, and the reference silicon concentration before adding the silicon,
Comparing the density of the initial value information with the plurality of second densities, selecting one of the plurality of second densities, selecting the first density corresponding to the selected second density, and selecting Comparing the first concentration and the concentration of the measurement value information, and determining the reference silicon concentration corresponding to the first concentration selected based on the result of the comparison as the silicon concentration of the liquid to be measured. A program for measuring silicon concentration according to claim 9.