JPH0743356B2 - Dispenser - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dispenser, and more specifically, a dispenser for handling a standard solution used in gas analysis using ion chromatography. It is related to vessels.

[Prior Art] With the miniaturization and high integration of semiconductor integrated circuits, it has become increasingly difficult to clean the atmosphere in semiconductor manufacturing plants. Therefore, in order to investigate the invention of the cause of pollution and the degree of pollution, various gas analyzes are conducted in semiconductor manufacturing factories.

By the way, conventionally, gas analysis of the atmosphere in a semiconductor manufacturing plant is performed by, for example, ion chromatography (as one of the commercial products of this analysis, an ion chromatograph analyzer manufactured by Yokogawa Electric Corporation).
Model IC200 or Model DS10), but when performing gas analysis by this ion chromatography, it is necessary to use a standard solution in advance to obtain a calibration curve in the analyzer. It is necessary to obtain this calibration curve for each analysis depending on the analysis target. Therefore, it is convenient to store and store a standard solution having a predetermined concentration so that the standard solution can be appropriately extracted as needed. Therefore, the following dispenser has been conventionally used.

This dispenser comprises a storage bottle for storing and storing the standard solution, and a piston pump attached to this storage bottle, and the piston pump stores and stores the standard solution in the storage bottle.
The structure is such that the stored standard solution can be appropriately extracted.

[Problems to be Solved by the Invention] However, in the conventional dispenser, both the storage bottle and the piston pump were formed of borosilicate low-alkali glass, and therefore, there were the following problems.

It is important to measure the level of these impurities because NOx and SOx, which are present in trace amounts in the atmosphere, cause contamination of the manufacturing process of semiconductor integrated circuit devices or the silicon substrate wafer that is the starting material. depending on the degree of environmental pollution, SO ₄ for SOx ^- it may include the 0.1～10Ng / air in terms), for analyzing these trace impurities such air, the standard liquid separation for preparing the calibration curve When the material of the injector is Pyrex, the glass components such as Na and K from the material are eluted into the standard solution, and of course the analysis of these eluted components is also required to detect the target NOx ion or SOx ion. The S / N ratio decreases due to the presence of the above alkali metal ions, and the output peak value of ion chromatography becomes significantly larger than the true value corresponding to the concentration of the target analysis chemical species, and its waveform is disturbed. , It is difficult to create an accurate calibration curve.

In addition, in the conventional dispenser, when the standard liquid is extracted by the piston pump, the upper space of the liquid reservoir is opened to atmospheric air, or a rubber balloon is used to slightly add the gas suction pipe below the piston pump. Since pressure is applied, the former causes pollution from atmospheric gas, and the latter causes pollution due to the material of the rubber balloon.

In semiconductor factories, the amount of analytes will become extremely small in the future, so it is necessary to prevent contamination of standard solutions such as elution from dispensers.

The present invention has been made in view of such a point, and it is possible to prevent elution of glass components from the dispenser, thereby preventing the standard solution from being contaminated, and providing a technique capable of analyzing ultratrace impurities. Is the main purpose.

[Means for Solving the Problems] The present invention relates to a storage bottle for storing and storing a standard solution used in gas analysis using ion chromatography, and a storage bottle attached to the storage bottle. In a dispenser equipped with a piston pump for appropriately extracting a standard solution, both the storage bottle and the piston pump, and their contents of impurities lithium, sodium, potassium, magnesium and calcium are both 0.1 ppm.
It is made of synthetic quartz glass (weight) or less, and a gas suction pipe is attached to the cylinder of the piston pump, and this gas suction pipe is flexible and airtight and can contain an inert gas. A bag made of a film-like sheet is attached, and the standard solution is extracted while applying a back pressure to the standard solution by the inert gas sealed in the bag.

[Operation] According to the present invention, since the dispenser is formed of sufficiently high-purity synthetic quartz glass, as will be apparent from the experimental results described later, it is possible to remove undesired glass components from the synthetic quartz glass into the standard solution. Since there is almost no elution, the contamination of the standard solution due to the material of the dispenser can be reduced, an accurate calibration curve can be obtained, and highly sensitive analysis can be performed.

Further, when using the above dispenser, a flexible and sufficiently airtight film sheet such as a polypropylene bag is attached to the cylinder of the piston pump, and back pressure is applied to the standard solution by the high-purity inert gas enclosed in the bag. By doing so, there is no contamination from the pressure source that applies the back pressure, and the contamination can be further reduced accordingly.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be illustratively described in detail with reference to the drawings.

1 to 3 show a dispenser according to an embodiment of the present invention.

The dispenser 1 is for storing a storage bottle 3 (FIG. 2) for storing and storing the standard solution 2, and for appropriately extracting a predetermined amount of the standard solution 2 stored and stored in the storage bottle 3. It consists of a piston pump 4 (Fig. 3) and these storage bottles 3
The piston pump 4 and the piston 5 and other dispensers of the present invention are, for example, Thermal Synd
It is made from Synthetic Vitreous Silica SPECTROSIL, which is synthetic quartz manufactured by icate Limited.

The following are the catalog analysis values of synthetic silica spectrosil.

Moreover, the sliding portions of the piston pump 4 and the piston 5 are finished with high precision and a mirror surface, and can slide airtightly and smoothly through a thin film of standard liquid without grease.

Here, the piston pump 4 includes a piston 5 and a cylinder 6 that stores the piston 5 slidably in the axial direction (vertical direction in the drawing). And
The outer surface of the lower end of the cylinder 6 of the piston pump 4 and the inner surface of the opening 3a of the storage bottle 3 are provided with a tapered portion having a shape and a finished surface which are airtightly fitted to each other without grease. The piston pump 4 can be attached to the storage bottle 3 by the connection.

A standard liquid suction pipe 7 having a diameter smaller than that of the cylinder 6 is attached to the inside of the lower portion of the cylinder 6, and the gas introduction pipe 7 communicated with a gas suction pipe 8 is provided around the standard liquid suction pipe 7. It has a structure in which the portion 9 is formed. Also, the cylinder 6
A standard solution discharge pipe 10 is attached to the.

Ball valves 12 and 13 are provided in the middle of the standard liquid suction pipe 7 and the standard liquid discharge pipe 10, respectively. In the ball valves 12 and 13, both balls 12a and 13a are made of synthetic quartz glass.

Further, the valve seats 12b, 13b for seating the balls 12a, 13a and the stoppers 12c, 13c for locking the balls 12a, 13a are provided inside the standard liquid suction pipe 7 and the standard liquid discharge pipe 10, respectively. It is formed integrally with the suction pipe 7 and the standard liquid discharge pipe 10.

Further, a bag 11 made of polypropylene in which an inert gas of 1 atm is sealed is attached to the gas suction pipe 8.

The operation of the dispenser 1 of the present embodiment configured as described above will be described. When the piston 5 is raised, the standard liquid 2 enters the cylinder 6 from the standard liquid suction pipe 7. In other words, as the piston 5 rises, the inside of the cylinder 6 becomes a back pressure acting on the standard solution 2 in the storage bottle 3 and a negative pressure with respect to the atmosphere.
Get in. At this time, the ball 12 that constitutes the ball valve 12
The a is separated from the valve seat 12b and abuts on the stopper 12c. On the other hand, the ball 13a constituting the ball valve 13 has a valve seat 1
It is on the 3b side.

When the piston 5 is lowered from this state, the internal pressure of the cylinder 6 becomes positive with respect to the back pressure used for the standard liquid 2 and the atmosphere, so that the standard liquid 2 is discharged from the standard liquid discharge pipe 10. At this time, the ball 12a forming the ball valve 12 is on the valve seat 12b side, while the ball 1 forming the ball valve 13 is
3a is in a state of being separated from the valve seat 13b and hitting the stopper 13c.

According to the dispenser 1 configured in this way, the following effects can be obtained.

That is, in the present embodiment, since the dispenser 1 is formed of synthetic quartz glass, the glass component mainly composed of alkaline is hardly eluted from the dispenser 1 to the standard solution 2.
Therefore, the contamination of the standard solution 2 due to the material of the dispenser can be reduced, and as a result of obtaining an accurate calibration curve, highly sensitive analysis is possible.

With respect to this point, an experiment was actually carried out to compare the amounts of components eluted from each glass into deionized water using a dispenser made of synthetic quartz glass and a dispenser made of borosilicate low alkali glass. The method and the result are described below.

In this experiment, it was decided to determine how much the standard solution in the dispenser made of synthetic quartz glass and the dispenser of borosilicate low-alkali glass would be contaminated. Put deionized water with a resistance of 18.2 MSL and dissolved oxygen (DC) concentration of 0.1 ppm, leave it at room temperature for 24 hours, and then, for these deionized water, set the output peak value corresponding to impurities by ion chromatography in the usual procedure. When measured, a second result was obtained. Pyrex glass was used as the borosilicate low-alkali glass. In addition, a polypropylene bag was attached to the cylinder of the piston pump of each dispenser, and high-purity N ₂ gas was enclosed in the bag.

From the table, it can be seen that when Pyrex glass is used, there is considerable alkali metal contamination. Due to the structure of the dispenser, the elements may be eluted from the vessel wall of the liquid reservoir, from the sliding part of the upper piston pump, or from the ball chuck valve. It is not clear why the NH ⁴⁺ peak was measured.

However, when synthetic quartz glass was used as the material, no output peak was detected.

Further, two dispensers made of synthetic quartz glass were prepared, a polypropylene bag was attached only to the cylinder of one piston pump, high-purity N ₂ gas was sealed inside, and the other was opened directly to atmospheric air. This has a specific resistance of 18.2
MΩ, deionized water of dissolved oxygen (DO) solution 0.1ppm,
After being left at room temperature for about 24 hours, the output peak of the deionized water was measured by ion chromatography in a usual procedure. The results are shown in Table 3.

From the table, ammonia ions were detected in the dispenser not equipped with a polypropylene bag, which is considered to be due to ammonia molecules or ammonia compound fine particles in the atmosphere. On the other hand, when the polypropylene bag is provided, the output peak is completely zero.

Next, nitrogen oxide and sulfur oxide in the atmosphere in the semiconductor wafer manufacturing plant are measured. First, prior to measurement, prepare a required number of solutions prepared by diluting the standard solution in which the ions to be analyzed are dissolved to a predetermined concentration, and analyze by ion chromatography to obtain the peak heights obtained during the analysis of each concentration. The concentration was plotted against the concentration and a calibration curve was drawn.

In this case, in general, the peak height of ion chromatography and the number of ions detected in the analytical instrument are in direct proportion, so if the ion concentration in the solution is uniform, the peak height and the ions in the solution It is directly proportional to the concentration. Therefore, if a calibration curve is created by a pipette with a high-purity nitrogen-filled polypropylene bag attached to the piston cylinder, there is no erroneous measurement element due to the pipette itself. If the same consideration is given to the material, trace impurities in the atmosphere can be measured with high accuracy.

First, in order to prepare a calibration curve, a standard solution is prepared using a measuring flask made of high-purity synthetic quartz glass of the present invention. That is, JIS special grade reagents NaNO ₂ , NaNO ₃ and K ₂ SO ₄
After drying at 110 ℃ for 2 hours, store and cool in a desiccator, then use an electronic balance to adjust the following amounts to ± 0.0003g.
With the accuracy of NaNo ₂ : 0.1500 ± 0.0003g NaNO ₃ : 0.2741 ± 0.0003g K ₂ SO ₄ : 0.3628 ± 0.0003g Using pure water, make an aqueous solution of 1 (25 ℃) in a volumetric flask. As a calibration curve standard mother solution, and further using the above-mentioned calibration curve standard mother solution with a micropipette and a measuring flask, three kinds of standard sample solutions are prepared at the measurement level, and actually subjected to ion chromatography, and the output Measure peak length etc.

Next, with an absorber made of synthetic quartz glass of the same material as the dispenser, the outside air intake of the air conditioner in the semiconductor wafer manufacturing plant,
Nitrogen oxides and sulfur oxides in the air in the cleaning room for semiconductor wafer final products (mirror-finished wafers), respectively
NO ₂ ^-, NO ₃ ^- were determined by and SO ₄ ^2-form. These ions appear to exist as NO, NO ₂ and SO ₃ in air.

As the absorbing liquid, 30 ml of deionized water having a specific resistance of 18.2 MΩ and a dissolved oxygen (DO) concentration of 0.1 ppm was placed in an absorption bottle at a constant temperature of 25 ° C.
Promptly fit the suction and discharge device. In addition, until the sampling starts, cap the absorption liquid so that there is no atmospheric contamination. At the time of sampling, set the flow rate of the absorption pump to 50 nml / min and aspirate a total of 500 nml for 10 minutes. After suction, quickly cap the suction nozzle and measure with an ion chromatograph analyzer.

The following table shows an example of measurement quantified using the above calibration curve.

[Effects of the Invention] The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

According to the present invention, a storage bottle for storing and storing a standard solution, and a component for ion chromatography provided with a piston pump attached to the storage bottle for appropriately extracting the standard solution in the storage bottle. In the injector, the storage bottle and piston pump were made of synthetic quartz glass, so there was almost no elution of glass components from the synthetic quartz glass to the standard solution, and the standard solution was not contaminated, enabling high-sensitivity analysis. Becomes

Further, when the dispenser is used, for example, if back pressure is applied to the standard solution by a gas sealed in polypropylene, the contamination of the standard solution is further hindered.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a dispenser of the embodiment, FIG. 2 is a front view of a storage bottle in the dispenser of the embodiment, and FIG. 3 is a front view of a piston pump in the dispenser of the embodiment. . 1 ... Dispenser, 2 ... Standard solution, 3 ... Storage bottle, 4 ...
Piston pump.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G01N 1/00 102 C 1/10 N

Claims (1)

[Claims] 1. A storage bottle for storing and storing a standard solution used in gas analysis using ion chromatography, and for appropriately extracting the standard solution attached to this storage bottle. In the dispenser equipped with the piston pump, both the storage bottle and the piston pump have 0.1 ppm of impurities contained therein, such as lithium, sodium, potassium, magnesium and calcium.
It is made of synthetic quartz glass (weight) or less, and a gas suction pipe is attached to the cylinder of the piston pump, and this gas suction pipe is flexible and airtight and can contain an inert gas. A dispenser characterized in that a bag made of a film-like sheet is attached, and the standard solution is extracted while applying back pressure to the standard solution by an inert gas sealed in the bag.