JP3853664B2 - Chemical solution preparation equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an apparatus for preparing a chemical solution containing an active ingredient at a predetermined concentration, and in particular, efficiently and efficiently uses various chemical solutions such as an etching solution, a cleaning solution, and a developer used in a photolithography system used in a semiconductor manufacturing process. The present invention relates to an apparatus that can be accurately prepared.
[0002]
[Prior art]
  In various semiconductor manufacturing processes such as an etching process, various chemicals such as an etching solution are used. However, the concentration of the active ingredient in the chemical greatly affects the processing accuracy and the yield. For this reason, the concentration of the active ingredient in these chemical solutions needs to be adjusted accurately and accurately.
  Conventionally, mixing tanks equipped with mixing means and external circulation paths have been used for the preparation of chemicals. However, it took time to make the chemical concentration in the mixing tank completely uniform. In addition, concentration measuring means for adjusting the concentration is required, but depending on the chemical solution, measurement errors may not be negligible due to bubble sensors caused by vortices generated by the stirring flow or turbulent flow generated in the vicinity of the sensor. .
[0003]
[Problems to be solved by the invention]
  Accordingly, an object of the present invention is to provide a liquid preparation apparatus or a mixing apparatus that can quickly obtain a uniform mixed liquid. It is another object of the present invention to provide a liquid preparation apparatus or a mixing apparatus that can perform precise and accurate concentration adjustment. Furthermore, it is another object to provide a method for preparing a chemical solution for manufacturing a semiconductor that can easily ensure various processing precisions.
[0004]
[Means for Solving the Problems]
  As a result of intensive studies to solve the above-described problems, the present inventors have completed the following invention. That is, according to the present invention, the following means are provided.
(1) An apparatus for preparing a chemical solution containing a component at a predetermined concentration,
  A mixing tank for mixing the active ingredient-containing solution of the chemical and the dilution liquid;
  A circulation path for flowing the liquid in the mixing tank out of the mixing tank and returning it to the mixing tank;
  A discharge unit connected to the return side of the circulation path and disposed in the mixing tank, and having a discharge port capable of discharging the liquid to be returned under the liquid level in the mixing tank;
  The discharge section is configured to rotate in one rotation direction or alternately in different rotation directions around the inner wall of the mixing tank,
  The discharge port protrudes from the lower end of the discharge portion so as to face the inner wall of the mixing tank, andA chemical solution preparation apparatus, wherein the directivity of the return liquid by the discharge port is any of the following.
(A) One or two or more of the discharge ports can discharge the return liquid from substantially horizontal to obliquely downward, pointing at two or more locations on the inner wall of the tank.
(B) The two or more discharge ports can discharge the return liquid substantially horizontally while being directed to different portions of the inner wall of the tank.
(C) The two or more discharge ports can discharge the return liquid obliquely upward while being directed to different portions of the inner wall of the tank.
(2)The mixing tank includes a first supply path for supplying the active ingredient-containing solution, and a second supply path for supplying the dilution liquid, and the first supply path and the second supply path. Are equipped with a large-volume supply pipe and a small-volume supply pipe,
  In connection with the circulation path or independently of the circulation path, the concentration measurement circulation path including the concentration measurement means and the weight measurement means for measuring the weight of the liquid in the mixing tank are provided in (1). The chemical | medical solution preparation apparatus of description.
(3)The position of the discharge port is 25% when the bottom surface of the mixing tank is at the 0% position and the half height of the liquid level corresponding to the appropriate mixing capacity from the bottom surface of the mixing tank is at the 50% position. The chemical solution preparation device according to (1) or (2), which is set within a range of 50% from the first position.
[0005]
  According to these inventions, the circulating and returned liquid is mixed into the mixing tank by the discharge unit.
It is discharged into the liquid inside. The discharge directing portion of the return liquid is in a different direction with respect to the circumference of the inner wall of the mixing tank. Or it moves in a different direction along the circumference of the inner wall of the mixing vessel. According to these mixing devices, a liquid flow in which the liquid returned from the external circulation path diffuses radially from the normal direction or the center directed to the inner wall of the mixing tank and a swirling flow that swirls in the mixing tank is formed. To do. As a result, the returned liquid itself is diffused so as to be uniformly distributed in the mixing tank. For this reason, the liquid mixed uniformly can be obtained rapidly, without generating a bubble.
  Concentration measuring means andWith weight measuring meansThe concentration of the liquid in the mixing tank can be detected. For this reason, accurate density control becomes possible.
  Further, when a large-volume supply pipe and a small-volume supply pipe are provided, the concentration can be roughly prepared by the large-volume supply pipe, and the concentration can be finely prepared by the small-volume supply pipe. For this reason, accurate and highly accurate density adjustment is possible.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described in detail.
  The preparation apparatus and the mixing apparatus of the present invention include a mixing tank, a circulation path for flowing out the liquid in the mixing tank from the mixing tank and returning it to the mixing tank, and the mixing tank connected to the return side of the circulation path. A discharge portion that is disposed within and has a discharge port capable of discharging the liquid to be returned under the liquid level in the mixing tank, andThe discharge section is configured to rotate in one rotation direction or alternately in different rotation directions around the inner wall of the mixing tank,
  The discharge port protrudes from the lower end of the discharge portion so as to face the inner wall of the mixing tank, andThe directivity of the return liquid by the discharge port is any of the following.
(A) One or two or more of the discharge ports can discharge the return liquid from substantially horizontal to obliquely downward, pointing at two or more locations on the inner wall of the tank.
(B) The two or more discharge ports can discharge the return liquid substantially horizontally while being directed to different portions of the inner wall of the tank.
(C) The two or more discharge ports can discharge the return liquid obliquely upward while being directed to different portions of the inner wall of the tank.
  This mixing vessel is used to finally prepare a uniform liquid, and can be used to mix a liquid and a solid in addition to a liquid and a liquid (including a solution). Particularly, it is suitable for preparing a chemical solution containing an active ingredient having a predetermined concentration by mixing an active ingredient-containing solution of a chemical solution and a diluted solution thereof.
  In addition, according to these apparatuses, when the return liquid is discharged below the liquid level in the mixing tank, it is uniform while avoiding the formation of a stirring flow that disturbs the liquid level. And can be mixed efficiently. Therefore, it can be preferably used in a case where a concentration measurement system that dislikes bubbles and pulsating flow is provided, or a chemical solution used in a processing step that dislikes bubbles. Furthermore, since a uniform liquid can be obtained quickly, a chemical solution with a predetermined concentration can be quickly prepared, and the accuracy and precision of concentration adjustment are high.
  Therefore, this chemical solution preparation device or mixing device is preferably used for preparing various chemical solutions and mixing liquids used in various processes such as etching process, polishing process, cleaning process, plating process, photolithographic process in semiconductor manufacturing. Can do.
[0007]
  Hereinafter, the present invention will be described in detail by exemplifying a liquid mixing apparatus (chemical solution preparation apparatus) 2 including the mixing means 40 according to the present invention.
  The chemical solution adjusting apparatus 2 illustrated in FIG. 1 mixes a 50 wt% aqueous solution of hydrogen fluoride (HF) and pure water as a diluting solution as an etching solution used in the etching process, to produce a 1 wt% HF aqueous solution. It is a device to prepare.
  The apparatus 2 includes a mixing unit 40 and a mixed material supply system 10. The mixing unit 40 includes a mixing tank 42, a circulation unit 60, and a uniformizing unit 70.
[0008]
  The mixed material supply system 10 includes storage portions 12 and 16 for each mixed material and supply paths 22 and 26 thereof. There are at least two types of mixed materials, but three or more types may be used depending on the composition of the chemical solution to be obtained. In this embodiment, the first mixed material is a 50 wt% HF aqueous solution, and the second mixed material is pure water. In this embodiment, the supply system for the liquid or fluid mixed material is mainly described. However, the solid mixed material may form a separate supply system. However, the solid mixed material is also preferably supplied to the mixing tank 42 in a solution state.
[0009]
  Each of the supply paths 22 and 26 can be configured as a single path, but can be branched into a large amount supply pipes 32 and 36 and a small amount supply pipes 34 and 38, respectively. In the large-volume supply pipes 32 and 36, each liquid can be supplied to the mixing tank 42 in large quantities, although each liquid has rough accuracy. The small amount supply pipes 34 and 38 can supply a small amount of liquid to the mixing tank 42 with high accuracy. Each pipe 32, 34, 36, 28 can be provided with a valve whose opening and closing is controlled by a control device. The control device controls the open / closed state of these valves based on the measurement results by the liquid weight measuring means 50 and the concentration measuring means 90 described later.
  Supply of the mixed material through the large-volume supply pipes 32 and 26 is preferable for supply at the initial stage of mixing, and supply of the mixed material through the low-volume supply pipes 34 and 38 is convenient for final fine adjustment of the concentration.
[0010]
  The mixing unit 40 includes at least a mixing tank 42, a circulation unit 60, and a uniformizing unit 70, and also includes a concentration measuring system 80 and a liquid weight measuring unit 50 in the mixing tank 42..
  The form of the mixing tank 42 is not particularly limited, and various types of mixing tanks conventionally used for mixing liquids can be used. In the present invention, since the external circulation path 62 is provided as the circulation means 60, it is preferable to have a bottom shape that converges downward and the cross-sectional shape becomes small. Specifically, it is conical, angular, hemispherical or the like.
[0011]
  The circulation means 60 includes a circulation path 62 and a forced circulation means 63. As the forced circulation means 63, conventionally known various pumps can be used. The circulation path 62 is configured so that the internal liquid flows out from the vicinity of the bottom of the mixing tank 42 and returns to the mixing tank 42. An end portion on the return side of the circulation path 62 has a uniformizing means 70 for discharging and mixing the circulated liquid into the liquid below the liquid surface in the mixing tank 42.
[0012]
  The homogenizing means 70 includes a discharge unit 71 that is capable of discharging a liquid to be returned below the liquid level of the mixed liquid in the mixing tank 42. The installation form with respect to the mixing tank 42 is not ask | required. As shown in FIG. 1, the discharge unit 71 can typically be installed so as to enter the mixing tank 42 from the upper side to the lower side of the mixing tank 42. The entry position of the discharge unit 71 into the mixing tank 42 is not particularly limited. That is, it may be near the vertical center of the mixing tank 42 or may be a position eccentric from the vertical center. As will be described later, when the discharge directing part to which the discharge port 72 of the discharge part 71 is directed is designed to be a part of the inner wall of the mixing tank 42 facing each other, the discharge part 71 is located near the vertical center of the mixing tank 42. It is preferable that they are arranged. On the other hand, when the discharge directing portions are designed at two locations in the range closer to the half circumference on the inner wall of the mixing tank 42, the discharge from the discharge unit 71 is a position away from the vertical center of the mixing tank 42. The mixing efficiency by the liquid can be increased.
[0013]
  The discharge part 71 is formed to discharge liquid toward the outside, that is, at two or more parts (discharge directing parts) of the inner wall of the mixing tank 42. By providing such a discharge part 71, the swirl | vortex flow along the inner wall in the mixing tank 42 can be formed. Two or more discharge units 71 may be provided.
  Each ejection part 71 can include one or more liquid ejection ports 72, respectively. Each discharge port 72 is formed so as to be able to discharge liquid from a substantially horizontal direction to an obliquely downward direction with respect to the discharge directing portion. Preferably, it is formed so that the return liquid can be discharged almost horizontally.
  In order for the discharge part 71 to be able to discharge the return liquid toward two or more locations on the inner wall of the mixing tank 42, various forms can be employed.
  For example, as shown in FIG. 2, when one discharge unit 71 is provided, two or more discharge ports 72 corresponding to two or more different discharge directing portions can be provided. According to this configuration, the return liquid can be discharged simultaneously or alternately to different discharge directing portions while the discharge portion 71 is fixed.
  Moreover, as shown in FIG. 3, when providing the branched discharge part 71, it can be made to equip each branch part with the 1 or more discharge port 72 which orients a different direction. Also in this form, the return liquid can be discharged simultaneously or alternately to different discharge directing portions with the discharge portion 71 fixed. In FIG. 3, a valve is provided for each of the branched discharge portions 71, but a three-way valve may be provided at the branch portion.
  Although not shown in the drawing, each of the two discharge portions 71 may be provided with one or more discharge ports 72 that are directed in different directions.
[0014]
  According to these various forms, the return liquid is returned to the inner wall of the mixing tank 42 in different directions by the discharge unit 71, thereby forming a liquid flow in the mixing tank 42 and returning the liquid. The flowed liquid is sufficiently diffused. Further, since the discharge liquid is directed toward the inner wall, the return liquid is supplied to the vicinity of the inner wall of the mixing tank 42 and reflected by the inner wall, so that a swirl flow along the inner wall is formed, and the entire mixing tank 42 is formed. The return liquid is efficiently diffused. In addition, it is possible to promote diffusion of components to be mixed by turbulence by forming swirl flows having different directions and by turbulence by collision of these swirl flows.
  That is, it can be said that the discharge part 71 of this invention is comprised so that a return liquid may be discharged so that the swirling flow from which directionality differs may generate | occur | produce in the mixing tank 42. FIG. If it demonstrates in detail, it can be said that it is comprised so that the swirl flow from which directionality differs may collide.
[0015]
  In order to enable the discharge unit 71 to discharge the return liquid in two or more places, the discharge unit 71 is moved.TheThe discharge directing portion is one direction along the circumference of the inner wall of the mixing tank 42 or different directions with respect to the discharge portion 71.The
  For example, as shown in FIGS. 1 and 4, the whole or a part of the discharge unit 71 including the discharge ports 72 oriented in two different directions is rotated around the axis of the discharge unit 71 in one direction or alternately different directions. Thus, such movement of the discharge directing portion can be achieved, and thereby the discharge of the return liquid directed to two or more portions can be realized. In this case, each discharge port 72 moves, so that each discharge port 72 discharges the return liquid to two or more discharge directing portions. Note that the liquid may be constantly discharged from the discharge port 72 or may be discharged intermittently.
  In addition, as shown in FIG. 5, by rotating one discharge portion 71 having one discharge port 72 around the axis of the discharge portion 71, the discharge directing portion is moved and discharge directed at two or more locations. Form can be realized. In this case, as shown in FIG. 5, it is effective to arrange the discharge portion 71 at a position eccentric from the center of the mixing tank 42 and to rotate in an arc shape directed toward the anti-eccentric side in the mixing tank 42.
  In addition, the rotation method of each discharge part 71 is when rotating continuously in one direction, when rotating alternately with reversal that repeats clockwise and counterclockwise alternately, and when rotating these together There is. From the viewpoint of uniform mixing, it is preferable to include alternate rotation. By alternating rotation, a swirl flow that opposes the swirl flow directed in the opposite direction of the liquid flow generated by the movement and reversal of the rotation is generated, and a turbulent flow region is generated by the collision of these swirl flows, thereby promoting diffusion. Is done. Even in the case of continuous rotation in the same direction, a large number of swirling flows directed in the same direction are continuously generated, and the discharge flow velocity is increased by the movement of the discharge port 72, so that turbulence / diffusion is Promoted.
  Furthermore, the two or more ejection units 71 can be continuously rotated in different rotational directions or in the same direction. In this case, the swirl directions are fixed, but since two types of swirl flows are generated and the discharge flow velocity is increased by the movement of each discharge port 72, turbulence and diffusion are achieved. Is promoted.
  From the above, the discharge unit 71 of the present invention generates a large number of swirling flows continuously or intermittently by movement of the discharge unit 71 of the discharge source (discharge port) (preferably rotation around the axis of the discharge unit 71). It can be said that it has the structure to generate.
  In addition, according to those skilled in the field related to various mixing devices including a liquid mixing device, in order to obtain such a rotatable discharge portion 71. It is obvious that various modes such as a movable joint can be taken. Therefore, those skilled in the art can select the configuration of the ejection unit 71 as necessary.
[0016]
  In addition, in these forms, when two or more discharge ports 72 are provided as a whole, it is preferably provided so as to be directed to different portions of the inner wall according to the number of discharge ports 72. By directing to different parts, the return liquid can be diffused in different directions at once. For example, it can be provided so as to be directed to portions that are evenly spaced along the circumference of the inner wall. Specifically, when there are two ejection ports 72, they can be provided so that they are directed at positions different from each other by 180 °, and when there are three, the outlets 72 can be directed at positions different from each other by 120 °.
  Moreover, although the height position to which it points is not specifically limited, the same height position may be sufficient and it can also combine so that different height positions may be pointed. Considering the promotion of turbulence due to the collision of the swirling flow, it is preferable to set the same height position. And it is preferable to direct toward the inner wall with the same directionality.
  The position of the discharge port 72 is,It is preferably set within the range of the half height position (50% position) of the liquid surface (or mixing tank) corresponding to the appropriate mixing volume from the bottom surface (0% position) of the mixing tank 42. . This is because if it is higher than the 50% position, the effect of promoting diffusion tends to be insufficient. More preferably, it is set within the range from the 25% position to the 50% position. This is because the most efficient diffusion mixing is possible within this range. This is because if the position is lower than the 25% position, it may be difficult to form a swirl flow.
[0017]
  Further, each discharge port 72 is formed so as to be able to discharge liquid from substantially horizontal to obliquely downward (preferably substantially horizontal) with respect to the discharge directing portion. By forming in this way, a swirling flow can be easily formed using the inner wall of the mixing tank 42, and a directional swirling flow that collides can be easily formed. In particular, when two or more discharge ports 72 are provided, the discharge is preferably performed so that the same height position is directed substantially horizontally.
Although not particularly limited, in the case of the diagonally downward direction, it is preferable to set the angle to about 30 ° from the horizontal.
  Further, the two or more discharge ports may be configured to discharge the return liquid in an obliquely upward direction. In this case, preferably, the same angle and the same height position are directed. A swirling flow can be formed in the entire mixing tank by directing obliquely upward.
  Such a discharge port 72 may be formed in a nozzle shape with respect to the discharge unit 71 or may be formed in a simple opening. Preferably, it is possible to obtain a discharge pressure and directivity that are necessary for the formation and diffusion of a swirling flow that promotes diffusion.
  The discharge port 72 is preferably formed so as to discharge liquid toward the central portion of the mixing tank 42 or the tank inner wall facing the eccentric position. When directing from the eccentric part toward the inner wall of the tank, it is preferable to direct the inner wall side (opposite side) farther away from each other.
  For example, the discharge port 72 can be a nozzle having such a liquid discharge directivity. Specifically, the discharge unit 71ofAn opening can be provided at the tip of a thin tube that is formed to project from the lower end toward the inner wall of the tank. The nozzle has good directivity of the liquid flow, and the discharge pressure can be increased by the shape of the nozzle tip. In addition, since the nozzle is formed so as to protrude from the discharge portion 71 toward the inner wall side, an action of stirring the inside of the mixing tank 42 occurs with rotation. Since the nozzle direction is the same as the directing portion of the return liquid, the nozzle itself can promote the diffusion of the return liquid discharged from the nozzle. In consideration of the stirring effect, the outer shape of the nozzle preferably has a large liquid resistance during rotation. For example, a flat shape with respect to the traveling (rotating) direction can be adopted.
[0018]
  In addition, the discharge part 71 can also be separately equipped with the stirring member which faces the mixing tank inner wall. In this case, by making the stirring member rotatable with the rotation of the discharge section 71, an effect equivalent to or more than that provided with the nozzle can be obtained. When providing a stirring member, it is preferable to provide two or more symmetrically. In terms of form, various shapes such as a wing shape having a high stirring effect can be employed. It can also be provided at different heights.
[0019]
  The mixing tank 42 is provided with weight measuring means 50 that can measure the weight of the mixed material supplied to the mixing tank 42. Various known means can be used as the weight measuring means 50, but a weight sensor such as a load cell is generally used. The weight measuring means 50 is connected to a control device (not shown), detects an increase in weight due to the supply of the mixed material to the mixing tank 42, recognizes the supply amount, and reaches a predetermined supply amount via the control device. As described above, opening and closing adjustment of valves of various supply pipes is performed. By providing the weight measuring means 50, the weight of the mixed material introduced into the mixing tank 42 can be accurately grasped or the supply amount can be controlled, so that efficient and accurate concentration control is possible. . In particular, when the supply system 10 includes a large amount supply system and a small amount supply system, the supply amount control and concentration control can be performed more effectively.
[0020]
  The liquid flows out from the vicinity of the bottom of the mixing tank 42 to the external circulation path 82 such as the circulation means 60 and the concentration measurement system. A rectifying plate 81 can be provided in the vicinity of the connection site of the outflow side piping so that vortex or pulsation does not occur in the outflowing liquid. The shape of the rectifying plate 81 is not particularly limited, and can be used by appropriately adopting conventionally known forms. By providing the current plate, in addition to accurate concentration measurement, processing accuracy in the manufacturing process of the semiconductor device can be ensured.
[0021]
  The mixing means 40 includes a concentration measurement system.TheThe concentration measuring system includes a concentration measuring unit. The concentration measuring means 90 is not particularly limited and may be employed as long as the concentration of a predetermined component in the liquid can be measured. Ultrasonic concentration measuring means can be preferably applied to many solutions in the manufacturing process of a semiconductor device.
  The concentration measurement system is preferably provided in a part of the external circulation path of the mixing tank 42. The introduction of the liquid from the mixing tank 42 to the concentration measuring system may be provided in the mixing tank 42 with a dedicated external circulation path for the concentration measuring system, but is provided along with the circulation path 62 of the circulating means 60. You can also. That is, in the latter case, a path from a part of the circulation path 62 to the concentration measuring means is branched. The return flow from the concentration measuring means to the mixing tank 42 may be provided through the circulation path 62 or may be provided so as to return to the mixing tank 42 without passing through the circulation path 62.
[0022]
  A mode in which a concentration measuring system 80 is provided independently of the circulating means 60 is shown in FIG. In this case, the circulation path 82 of the concentration measurement system 80 is provided with a forced circulation means (pump) 83 for circulating the liquid. From the viewpoint of ensuring concentration measurement accuracy by suppressing turbulent flow, it is preferable to use a pump having a Reynolds number of 60 or less.
[0023]
  In the path leading to the concentration measuring means 90 on the concentration measuring circulation path 82, it is preferable to provide a gas-liquid separating means 84 for separating bubbles in the liquid. This is because the measurement means decreases measurement accuracy due to the presence of bubbles. In particular, when the ultrasonic concentration measuring means is employed, the risk is high. Although various means can be adopted as the gas-liquid separation means 84, it is preferable to adopt a gas-liquid separation tank in that the configuration is simple.
[0024]
  When employing a gas-liquid separation tank, it is preferable to install the gas-liquid separation tank so that the liquid level of the tank is higher than the liquid level of the mixing tank 42. Due to the difference in the liquid level, the liquid can be easily transferred from the gas-liquid separation tank to the concentration measuring means 90. In the form shown in FIG. 1, the liquid is transferred by the pipe 86.
  In particular, when an ultrasonic concentration measuring means is employed, the position of the ultrasonic concentration measuring means with respect to the gas-liquid separation tank can be set so that an ascending laminar flow can be formed at the concentration detection cell portion of the means. preferable. As described above, when the concentration measurement is performed on the upward flow caused by the head, it is possible to perform the measurement with high accuracy. Further, it is preferable to set the position of the concentration measuring means with respect to the gas-liquid separation tank or the mixing tank 42 so that the liquid is transferred from the concentration measuring means to the mixing tank 42 due to the difference in liquid level. Further, from the viewpoint of harmonizing the atmosphere around the chemical solution, the gas-liquid separation tank and the mixing tank 42 are preferably communicated with each other through a vent pipe.
[0025]
  In the path from the concentration measuring means to the mixing tank 42, a valve for setting a flow rate preferable for concentration measurement, the flow rate adjusting means 100, and the like can be provided.
[0026]
  In general, a pipe for supplying the solution prepared in the mixing tank 42 to the use site is connected to the preparation device 2 or the mixing means 40. Such a pipe may be branched from the circulation means 60 described above or may be formed independently.
[0027]
  Next, a process of preparing a chemical solution using the preparation apparatus 2 including such a mixing unit 40 will be described.
  First, for example, a predetermined amount of 50% hydrogen fluoride aqueous solution and pure water are supplied to the mixing tank 42 via the supply system 10 via the large-volume supply pipes 32 and 36, respectively. Both liquids are circulated by driving the forced circulation means 63 of the circulation means 60 attached to the mixing tank 42. In the step of homogenizing or mixing the material with the return flow liquid, the above-described action of the swirling flow formed by the discharge portion 71, that is, the action of promoting the diffusion due to the collision and / or turbulent flow of the swirling flow, Mixing and homogenization in the process proceeds efficiently.
[0028]
  At the same time, the concentration of the active ingredient in the mixed solution in the mixing tank 42 is measured by the concentration measuring means 90. If a signal relating to the measured concentration is input to a control device (not shown), the amounts of 50% aqueous hydrogen fluoride solution and water necessary to finally obtain the desired concentration are calculated.
  Further, it is possible to confirm whether or not mixing has been sufficiently achieved by measuring the concentration with the concentration measuring means 90. For example, if the concentration measurement result by the concentration measuring means 90 is monitored, it is determined by the control device whether or not the process of homogenizing the liquid in the mixing tank 42 should be terminated from the data regarding the concentration fluctuation obtained by the monitoring. Can do. Based on the determination by the control device, it is possible to control the operation stop of the circulation means 60 and / or the start of the supply operation of the additional mixed material.
[0029]
  When it is necessary to supply an additional mixed material, it is preferable to supply by using small amount supply pipes 34 and 38 in order to secure an accurate supply amount. At the same time, it is preferable to detect the supply amount by the weight measuring means 50.
  After the additional supply of the mixed material, it is preferable to operate the circulation means 60 and detect the concentration by the concentration measuring means 90, as in the case of the first supply of the mixed material. A chemical solution having a desired concentration can be obtained by repeating the mixed material supply step and the mixing step.
[0030]
  Although the chemical liquid preparation process has been described above, the application target of the present invention is not limited to a solution such as a chemical liquid, and the present invention can be applied as long as the liquid is prepared through mixing.
[0031]
  FIG. 7 shows the change over time in the mixing state when pure water and an alkaline chemical are mixed using the liquid mixing apparatus of the present invention. In this mixed system, pH was used as an item for grasping the mixed state together with or instead of the concentration measurement.
  This mixed system was tested using the apparatus shown in FIG. This device has a circulation path in which the mixing tank is about 10 L, and the chemical liquid is forcibly circulated by a pump. And the discharge part which discharges a liquid via a movable joint is provided in the end by the side of the return of a circulation path. This discharge part infiltrates into the chemical | medical solution in a mixing tank in the position eccentric from the center of the mixing tank. The mixing condition by this discharge part is about 5L / min of circulation rate, discharge flow rateTheMix at about 2.2 m / s, changing the discharge direction every 30 seconds.As a control, mixing was performed using the same apparatus with the discharge direction fixed in one direction. The results are also shown in FIG.
  As shown in FIG. 7, according to the apparatus of the present invention, the pH could be stabilized in about 60% of the time compared with the conventional method.
[0032]
  FIG. 8 shows the monitoring results over 45 consecutive days of the blending process in which a 50 wt% hydrogen fluoride (HF) solution is diluted to 1 wt%. In this mixed system, concentration measurement was performed with an ultrasonic densitometer and also by a neutralization titration method, and the accuracy by ultrasonic concentration measurement was confirmed. Sampling was performed at a rate of once every 1-2 days.
  In this blending step, an apparatus similar to that shown in FIG. 1 was used, except that the ejection unit having two different ejection directing portions was provided. The mixing conditions were approximately 250 liters of chemical solution, 50 to 55 L / min of circulating fluid, a discharge flow rate of 2.2 m / sec (preferably 1.5 to 2.2 m / sec), and 2 every 3 minutes. The discharge direction was switched by alternately discharging the chemical solution from the two discharge portions. SwitchTimeIn this case, the impact on the circulation path system parts due to a water hammer or the like is reduced by simultaneously discharging for a few seconds (about 3 seconds in this embodiment).
    As shown in FIG. 8, according to mixing (preparation) using this apparatus and concentration measurement using an ultrasonic densitometer, it was possible to secure concentration stability sufficiently within an allowable range with respect to the reference value (1 wt%). Further, it was found that the difference between the concentration obtained by the ultrasonic densitometer and the concentration obtained by neutralization titration was small, and the ultrasonic densitometer could be measured with sufficient accuracy.
[0033]
【The invention's effect】
  ADVANTAGE OF THE INVENTION According to this invention, the liquid preparation apparatus or the liquid mixing apparatus which can obtain a uniform liquid mixture rapidly can be provided. In addition, according to the present invention, highly accurate concentration measurement can be achieved.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of a mixing apparatus according to the present invention.
FIG. 2 is a diagram showing an embodiment of a discharge unit according to the present invention.
FIG. 3 is a view showing another embodiment of the discharge unit of the present invention.
FIG. 4 is a view showing another embodiment of the discharge unit of the present invention.
FIG. 5 is a view showing another embodiment of the discharge section of the present invention.
FIG. 6 is a diagram showing an outline of an apparatus used for a mixing test of pure water and an alkaline chemical solution.
7 is a graph showing a change over time in a mixed state when pure water and an alkaline chemical solution are mixed by the apparatus shown in FIG. 6. FIG.
FIG. 8 is a diagram showing a monitoring result of a dilute preparation step of hydrogen fluoride.
[Explanation of symbols]
  2 Mixing device
  10 Supply system
  40 Mixing means
  42 Mixing tank
  60 Circulation means
  62 Circulation route
  70 Uniform means
  71 Discharge part
  72 Discharge port
  80 Concentration measurement system
  82 Circulation Route
  84 Gas-liquid separation means
  90 Concentration measuring means
  100 Flow rate adjusting means

Claims (3)

An apparatus for preparing a chemical solution containing a component of a predetermined concentration,
A mixing tank for mixing the active ingredient-containing solution of the chemical and the dilution liquid;
A circulation path for flowing the liquid in the mixing tank out of the mixing tank and returning it to the mixing tank;
A discharge unit connected to the return side of the circulation path and disposed in the mixing tank, and having a discharge port capable of discharging the liquid to be returned under the liquid level in the mixing tank;
The discharge section is configured to rotate in one rotation direction or alternately in different rotation directions around the inner wall of the mixing tank,
The discharge port projects from the lower end of the discharge unit so as to face the inner wall of the mixing tank, and the directivity of the return liquid by the discharge port is any of the following.
(A) One or two or more of the discharge ports can discharge the return liquid from substantially horizontal to obliquely downward with two or more locations on the inner wall of the tank.
(B) The two or more discharge ports can discharge the return liquid substantially horizontally while being directed to different locations on the inner wall of the tank.
(C) The two or more discharge ports can discharge the return liquid obliquely upward while being directed to different portions of the inner wall of the tank. The mixing tank includes a first supply path for supplying the active ingredient-containing solution, and a second supply path for supplying the dilution liquid, and the first supply path and the second supply path. Are equipped with a large-volume supply pipe and a small-volume supply pipe,
2. A concentration measurement circulation path including a concentration measurement means and a liquid weight measurement means for measuring the weight of the liquid in the mixing tank, in association with the circulation path or independently of the circulation path. The chemical | medical solution preparation apparatus of description. The position of the discharge port is 25% when the bottom surface of the mixing tank is at the 0% position and the half height of the liquid level corresponding to the appropriate mixing capacity is 50% from the bottom surface of the mixing tank. The chemical solution preparation device according to claim 1, wherein the chemical solution preparation device is set within a range of 50% from the first position.

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