JPH0423730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a measuring/mixing device used for measuring and mixing various liquids, such as a cleaning liquid for silicon wafers and a chemical liquid for preparing an etching liquid. .

[Prior art] For example, a processing solution for surface treatment (cleaning, etching, etc.) of silicon wafers, etc. contains a cleaning agent such as ammonia, sulfuric acid, or hydrochloric acid and an oxidizing agent such as hydrogen peroxide in a predetermined ratio. A mixed solution is used. In order to obtain good processing effects using such processing liquids, it is necessary to accurately adjust the mixing ratio.

By the way, many of the undiluted solutions used to prepare cleaning solutions are highly corrosive, so when measuring such undiluted solutions with a general-purpose flowmeter, metal ions etc. may be present in the solution due to the material of the flowmeter. There is a problem that the solution deteriorates due to elution.

There is also a method of supplying each stock solution at a constant flow rate to a mixing container in which each stock solution is mixed, and controlling the supply amount of each stock solution by adjusting the supply time. Since the flow rate tends to change easily, accurate measurement is difficult.

Therefore, attempts have been made to measure the supply amount of the stock solution by weight, and as an example, as shown in FIG. , and an inlet pipe 4 connected to the liquid feeding pipe 3, and the weight of the fed chemical solution is measured based on the amount of change in the weight of the measuring container 2 before and after the feeding of the chemical solution. It has been known.

However, in the above-mentioned measuring device, if the feeding speed of the chemical solution is constant, as shown by the imaginary line in FIG. From time T ₁ onwards, measuring container 2
The weight of the weighing container 2 should increase linearly, but in reality, the dynamic load and falling load F _M of the chemical solution act on the platform scale 1, so the weight of the weighing container 2 measured by the platform scale 1 increases as shown by the solid line. Even if the on-off valve 6 is closed when the apparent weight change becomes larger than the actual weight change and the weight change reaches the target point _W0 , the chemical solution that has already left the inlet pipe 4 remains in the measuring container. There is a problem in that sufficient measurement accuracy cannot be obtained because the sample falls into the container.

Moreover, as shown in FIG. 4a, a closed measuring container 7
It is also possible to consider a metering device in which an inlet pipe 8 fixed to
This is preferable in order to prevent dust from entering the inside.

However, in the metering device of FIG. 4a, as shown in FIG. 4b, after the start of liquid feeding, after the time _T1 when the chemical liquid reaches the liquid surface, the amount of liquid applied to the inlet pipe 8 as the chemical liquid is jetted out is The reaction force F _R and the above-mentioned dynamic load such as the chemical liquid and falling load F _M are balanced and temporarily have no effect on the amount of weight change, but when the target value W ₀ is reached, the on-off valve 6 is closed. Similarly to the above, there is a problem in that the chemical liquid that has already left the inlet pipe 8 falls into the measuring container 7, increasing the amount of chemical liquid supplied and distorting the measured value, so that good measuring accuracy cannot be obtained. do not have. Furthermore, in the measuring device shown in Fig. 4a,
As the platform scale 1 is displaced downward during liquid feeding, a large tensile load is applied from the liquid feeding pipe 3 to the measuring container 7.
There is a problem in that this acts as a load on the platform scale 1, further reducing measurement accuracy.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and it improves the measuring accuracy of a type of measuring device that uses a platform scale to measure liquid by weight, and also improves the measuring accuracy of a measuring device that measures liquid by weight using a platform scale. The purpose of this invention is to efficiently mix liquids that have been mixed together to prepare a liquid having the required component ratio.

[Structure of the Invention] Therefore, in the present invention, a weighing/mixing container whose upper part is sealed by a lid member, a platform scale placed on a fixed stand and supporting the weighing/mixing container, and a plurality of weighing/mixing containers are provided. a plurality of inlet pipes each having one end connected to the liquid feeding pipe and each other end inserted into the bottom of the measuring/mixing container to allow the liquid fed from each liquid feeding pipe to flow into the measuring/mixing container; An outlet pipe whose one end is inserted into the measuring/mixing container and for discharging the liquid in the measuring/mixing container, a discharge/circulation pump whose suction side is connected to the other end of the outlet pipe, and a discharge pipe of the discharge/circulation pump. A discharge pipe that is connected to the side and has an on-off valve interposed in the middle, and a return pipe that branches from the upstream side by the on-off valve of the discharge pipe and reaches the measuring/mixing container, and has an on-off valve interposed in the middle. The plurality of inlet pipes, outlet pipes, and return piping are arranged above the measuring/mixing container, and includes means for causing air to flow into or out of the measuring/mixing container as the fluid in the measuring/mixing container increases or decreases. The pipe is vertically piped, and the middle of the vertical part is formed as a spiral pipe part that can be expanded and contracted in the vertical direction.
Each vertical section is fixedly supported by a fixed frame above the spiral tube section, and supported below the spiral tube section by a pipe joint provided on the lid member of the measuring/mixing container,
While supplying liquid from each inlet pipe, the supply amount is measured using a platform scale, and when the supply amount of each liquid reaches a preset amount, the supply of each liquid is stopped, and then the discharge/circulation pump is activated. A liquid characterized in that the on-off valve of the discharge pipe is closed, the on-off valve of the return flow pipe is opened, and the liquid in the measuring/mixing container is circulated and mixed through the route of the outlet pipe and the return flow pipe. It provides measuring and mixing equipment.

As the platform balance, it is preferable to use, for example, an electromagnetic force self-balancing electronic balance or a load cell type balance.

[Effects of the Invention] According to the present invention, the lower end of each inlet pipe is
Since it is immersed in the liquid in the mixing container, the falling load of liquids such as chemical solutions is eliminated, and the dynamic load of the liquid spouted from the lower end of each inlet pipe is always balanced with the reaction force applied to each inlet pipe. Become. Moreover, since excess liquid is not supplied to the measuring/mixing container after the supply of liquid is stopped, the amount of liquid supplied to the measuring/mixing container can be accurately measured.

In addition, above the lid member of each inlet pipe, outlet pipe, and return pipe, there is a spiral that expands and contracts as the measuring/mixing container moves up and down on the platform scale as the liquid in the measuring/mixing container increases or decreases. In addition to forming a pipe part, the upper side of the spiral pipe part is supported by a fixed frame, so the weight of the inlet pipe can be received by the fixed frame, and the weighing/mixing container can move up and down as the platform scale changes. Even when moving, the vertical movement can be absorbed by the expansion and contraction of the spiral tube section, so even when many tubes are connected, there is no need to apply large tensile loads to the weighing/mixing container.
No compressive load is applied, and therefore measurement accuracy can be further improved.

Furthermore, since the measuring and mixing container is a closed type,
This prevents foreign matter such as dust from entering the liquid in the measuring/mixing container, thereby preventing the liquid from deteriorating during measuring.

On the other hand, since the circulation system is configured by the outlet pipe, the discharge/circulation pump, and the return piping, the liquid can be circulated and mixed immediately after measurement is completed, and the liquid with the required mixing ratio can be prepared with high precision.

[Example] Examples will be described below.

FIG. 1 shows a compounding device for preparing a cleaning solution for wafers such as silicon. Ammonia 11
A sealed and movable first replenishment container 13 for replenishing
, a second storage container (not shown) for storing the hydrogen peroxide solution, a second replenishment container (not shown) for replenishing the second storage container with the hydrogen peroxide solution, and a second storage container (not shown) placed on the fixed base 19. A closed weighing/mixing container 15 is placed on a platform scale 14 (electromagnetic force self-balancing electronic balance or load cell type balance), and the first storage container 12, the second storage container and the pure water supply port 16 are connected to each other. A measuring/mixing device 17 that measures and mixes the supplied ammonia 11, hydrogen peroxide solution, and pure water, respectively, and a third sealed storage container 20 that stores the cleaning liquid 18 prepared in the measuring/mixing container 15. It is composed of. Note that the cleaning liquid 18 may be directly supplied from the measuring/mixing container 15 to a wafer cleaning tank (not shown).

Detectors 21 and 22 are installed in the first storage container 12 to detect a preset upper limit level L ₁ and lower limit level L ₂ of the ammonia 11 liquid level, so that the ammonia 11 liquid level is always at the upper limit level. L ₁
and the lower limit level _L2 .
Ammonia 11 is now supplied from the replenishment container 13 by a liquid feeding pump 25 (air-driven bellows pump) through a liquid feeding pipe 24 having a liquid detector 23 for detecting the distribution status of ammonia 11. There is. The liquid feeding pump 25 connects a driving air supply port 26 to a pressure regulator 27 and a pressure gauge 28.
It is driven by compressed air supplied through an air pipe 30 with an interposed air pipe.

Moreover, the ammonia 11 in the first storage container 12 is
High-pressure gas (air, nitrogen, etc.) is supplied from the pressurized gas supply port 31 through a gas pipe 35 in which a pressure regulator 32, a gas filter 33, and a pressure gauge 34 are installed, and the liquid supply pipe 36 and the inlet pipe 37 are It is designed to be supplied to the measuring/mixing container 15 through the pipe.

The inlet pipe 37 connects the lower end of a spiral pipe 40 provided above a lid member 38 that seals the upper part of the measuring/mixing container 15 and the upper end of a straight pipe 41 disposed inside the measuring/mixing container 15. The spiral pipe 40 is connected to a member 38 by a pipe joint 42 fixed to the member 38, and the spiral pipe 40 is designed to absorb vertical movement of the weighing/mixing container 15 on the platform scale 14 due to increase or decrease of liquid in the weighing/mixing container 15. It is made of resin such as Teflon so that it can expand and contract.

The longitudinal center line of the spiral tube 40 is oriented in the vertical direction, and the upper end of the spiral tube 40 is located between the fixed frames 43, 43, which are erected on both sides of the platform scale 14 of the fixed table 19. It is connected to the liquid feeding pipe 36 via a pipe joint 45 on the suspended bar 44, and the upper and lower ends of the spiral pipe 40 are located on the center line.

On the other hand, the lower end of the straight pipe 41 forming the injection nozzle is located near the bottom 15a of the measuring/mixing container 15 so as to be immersed in the liquid in the measuring/mixing container 15 at all times. That is, a lower limit level L ₃ higher than the lower end of the straight pipe 41 of the inlet pipe 37 is set in the metering/mixing container 15 so that the liquid level in the metering/mixing container 15 does not fall below the lower limit level L ₃ .
The output signal of the platform scale 14, that is, the weighing/mixing container 15
Based on the weight of the liquid, the amount of liquid discharged from the measuring/mixing container 15 is limited.

The amount of ammonia 11 supplied from the first storage container 12 to the measuring/mixing container 15 is measured by the platform scale 14 as the amount of change in the weight of the measuring/mixing container 15 before and after the ammonia 11 is supplied. In this embodiment, since the lower end of the straight pipe 41 of the inlet pipe 37 is constantly immersed in the liquid in the metering/mixing container 15, the falling load of the ammonia 11 is eliminated when the ammonia 11 is supplied, and the dynamic load of the ammonia 11 is eliminated. Since the reaction force applied to the straight pipe 41 is canceled out by the reaction force applied to the straight pipe 41, for example, if the feeding speed of the ammonia 11 is constant, the weight of the measuring/mixing container 15 increases linearly as shown in FIG. The amount of weight change of the mixing container 15 is the target value
When the on-off valve 46 installed in the liquid supply pipe 36 is closed when W ₀ is reached, the supply of ammonia 11 to the measuring/mixing container 15 is immediately stopped, making it possible to accurately measure the supply amount. I can do it.

On the other hand, the hydrogen peroxide solution is supplied from the second storage container via the liquid supply pipe 47 and the inlet pipe 50 consisting of a spiral pipe 48 and a straight pipe 49, and pure water is supplied from the pure water supply port 16 to the pressure regulator. 51 and an inlet pipe 55 consisting of a spiral pipe 53 and a straight pipe 54, respectively, to the metering/mixing container 15, and each metered ammonia 11 in the same manner as described above;
Hydrogen peroxide and pure water are mixed at a predetermined mixing ratio. The lower ends of both the straight pipes 49 and 54 are connected to the straight pipe 41.
Similarly, it is located below the lower limit level _L3 .

The above-mentioned liquid mixture is connected to a spiral pipe 61 and a part of a discharge pipe 60 that connects the measuring/mixing container 15 and the third storage container 20 continuously to an outlet pipe 58 consisting of a straight pipe 56 and a spiral pipe 57. A circulation path 6 including a measuring/mixing container 15 formed by a return flow pipe 62
3, circulation/discharge pump (bellows pump) 6
The washing liquid 18 is circulated and stirred by the suction force and discharge force of No. 4, and a cleaning liquid 18 having a uniform composition is prepared. Note that the discharge pipe 60 and the return flow pipe 62 are provided with on-off valves 71 and 72, respectively, downstream of the branch part, and during circulation, the on-off valve 71 is closed and the on-off valve 72 is opened.
Also, during the circulation, the cleaning liquid 1 is removed by the fluid filter 65.
The cleaning liquid 18 is filtered to remove impurities, and the temperature of the cleaning liquid 18 is adjusted by a heat exchanger 66.
The thoroughly stirred and filtered cleaning liquid 18 is then transferred to the third storage container 20 or the aforementioned cleaning tank through the discharge pipe 60. The amount of cleaning liquid 18 supplied from the measuring/mixing container 15 to the third storage container 20 or the cleaning tank is measured by the platform balance 14.

The measuring/mixing container 15 is equipped with a ventilation filter 6.
7 is provided with an air supply and exhaust pipe 68 for measuring and
Air is supplied to or discharged from the measuring/mixing container 15 as liquid is supplied to or discharged from the mixing container 15.

The amount of vertical displacement of the platform scale 14 due to the supply and discharge of liquid to and from the weighing/mixing container 15 depends on the capacity of the weighing/mixing container 15, but the platform scale 14 may be either an electromagnetic force automatic balance type electronic balance or a load cell type balance. (Electromagnetic force self-balancing electronic balances have a reference height and are always controlled to this height, but if there is a large load fluctuation, , some fluctuations are repeated until equilibrium is reached), and during this vertical displacement, tension or , no compressive load acts, and each helical tube 4
Since only a weak tensile or compressive load is applied from 0, 48, 53, 57, and 61, the vertical displacement of the platform scale 14 has very little effect on the measurement accuracy.

In that case, the support height of the upper support bar 44 is the natural length of each tube (i.e., the length from the upper support bar 44 to the lid member 38 ) is preferable. In that case, each tube will be in an equilibrium state with liquid flowing, so when measuring, there will be no force other than the tensile and compressive forces associated with the vertical movement of the measuring and mixing container. No extra forces are generated in the helical tube section.

Furthermore, when an electronic balance or a load cell type balance as described above is used, the vertical movement of the weighing/mixing container is extremely small and can be ignored, making it possible to further improve the weighing accuracy as a whole.

In addition, in the above embodiment, the measuring/mixing device 17
Although the case where ammonia 11, hydrogen peroxide solution, and pure water are mixed to prepare a cleaning liquid for the surface of a silicon wafer has been explained, the measuring/mixing device 17 is not limited to mixing a processing liquid for silicon wafers, but can also be used for various other purposes. Needless to say, it can be used not only for mixing a plurality of medicinal solutions, but also as a measuring device for a single medicinal solution.

[Brief explanation of drawings]

Fig. 1 is an overall explanatory diagram of a silicon wafer cleaning liquid preparation device equipped with a measuring/mixing device according to the present invention, and Fig. 2 shows the time after the start of measurement in the measuring/mixing device shown in Fig. 1 and the time of measuring containers. Graph showing the relationship with the amount of weight change, Figure 3a is an explanatory diagram of the first conventional example, Figure 3b is a graph corresponding to Figure 2 of the first conventional example, Figure 4a is the second conventional example Explanatory diagram of Figure 4b
is a graph corresponding to FIG. 2 of the second conventional example. 11... Ammonia (liquid), 14... Platform scale,
15...Measuring/mixing container, 15a...Bottom, 19
...Fixing stand, 36, 47, 52...Liquid delivery piping, 3
7, 50, 55... Inlet pipe, 38... Lid member, 4
0, 48, 53...Spiral tube part, 43...Fixed frame, 58...Outlet pipe, 60...Discharge piping, 62
...Return piping, 63...Circulation path, 64...Discharge/
Circulation pump, 68... Supply/exhaust pipe, 71, 72...
Open/close valve.

Claims (1)

[Scope of Claims] 1. A measuring/mixing container whose upper part is sealed by a lid member, a platform scale placed on a fixed stand and supporting the measuring/mixing container, and a plurality of liquid feeding pipes, respectively. A plurality of inlet pipes, each of which is connected at one end and inserted into the bottom of the metering/mixing vessel at the other end, allows the liquid delivered from each liquid delivery pipe to flow into the metering/mixing vessel; An outlet pipe inserted into the container to discharge the liquid in the measuring/mixing container, a discharge/circulation pump whose suction side is connected to the other end of the outlet pipe, and a discharge/circulation pump connected to the discharge side of the discharge/circulation pump. A discharge pipe with an on-off valve in the middle, a return pipe that branches from the upstream side using the on-off valve in the discharge pipe and reaches the measuring/mixing container, and a return pipe with an on-off valve in the middle, and inside the measuring/mixing container. The plurality of inlet pipes, outlet pipes, and return piping are vertically piped above the measuring and mixing container. The middle part of the vertical part is formed as a spiral pipe part that can be expanded and contracted in the vertical direction, and each vertical part is fixedly supported by a fixed frame above the spiral pipe part, while measuring and mixing is carried out below the spiral pipe part. It is supported by a pipe joint installed on the lid of the container, and while supplying liquid from each inlet pipe, the supply amount is measured using a platform scale, and when the supply amount of each liquid reaches a preset amount, each After stopping the supply of liquid, operate the discharge/circulation pump, close the on-off valve of the discharge piping,
A liquid measuring/mixing device characterized in that an on-off valve of a return flow pipe is opened to circulate and mix the liquid in a measuring/mixing container through an outlet pipe and a return flow pipe route. 2. The liquid measuring and mixing device according to claim 1, wherein the platform scale is an electromagnetic force self-balancing electronic balance or a load cell type balance.