Process and apparatus for precise volumetric diluting/mixing of chemicals

• US 5,370,269 A
• Filed: 03/22/1993
• Issued: 12/06/1994
• Est. Priority Date: 09/17/1990
• Status: Expired due to Term

• Current Assignee: Air Liquide Electronics US LP (Air Liquide SA)
• Original Assignee: Applied Chemical Solutions, Inc. (Tokyo Electron Limited)
• Inventors: Bernosky, Eugene W., Roberson, Glenn A. Jr., Geatz, J. Tobin, Ferri, Edward T. Jr.
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): Bomberg, Kenneth
• Application Number:
  US08/035,252
• Time in Patent Office: 624 Days
• Field of Search: 222/1, 222/43, 222/56, 222/59, 222/61, 222/64, 222/66, 222/135, 222/145, 222/152, 222/309, 222/318, 222/399, 222/71, 137/205, 137/208, 137/209, 137/545
• US Class Current: 222/61
• CPC Class Codes: B01F 2101/2204 Mixing chemical components in generals in order to improve chemical treatment or reactions, independently from the specific application
• CPC Class Codes: B01F 35/2217 Volume of at least one component to be mixed
• CPC Class Codes: B01F 35/882 using measuring chambers, e.g. volumetric pumps, for feeding the substances
• CPC Class Codes: B24B 37/04 designed for working plane surfaces
• CPC Class Codes: B67D 7/0272 specially adapted for transferring liquids of high purity
• CPC Class Codes: B67D 7/0277 using negative pressure
• CPC Class Codes: B67D 7/0283 specially adapted for transferring liquids of high purity
• CPC Class Codes: G01F 11/28 with stationary measuring chambers having constant volume during measurement
• CPC Class Codes: G01F 23/00 Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
• CPC Class Codes: G01F 23/02 by gauge glasses or other apparatus involving a window or transparent tube for directly observing the level to be measured or the level of a liquid column in free communication with the main body of the liquid
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67276 Production flow monitoring, e.g. for increasing throughput program-control systems per se G05B19/00, e.g. total factory control G05B19/418

Abstract

Apparatus and method for accurate measuring and mixing of chemicals is disclosed. The apparatus includes one or more metered vessels having a container of predetermined volume and at least one constricted vent tube therein. By mounting a sensor on the constricted vent tube, a greatly amplified measurement of the precise chemical volume in the metered vessel is provided. The apparatus and method of the present invention readily lends itself to a variety of applications and can be adapted to handle virtually any form of chemical mixing, diluting, or generating process.

Claims

1. Apparatus for accurately mixing chemicals from two or more bulk sources which comprises:

a first intake line providing fluid communication of chemical between a first bulk source and a first metered vessel;

a second intake line providing fluid communication of chemical between a second bulk source and a second metered vessel;

a dispense line providing fluid communication between each of the meter vessels and a down-stream facility;

wherein each of the metered vessels comprises;

a container of predetermined volume;

at least one constricted fill tube, which constricted tube is filled once the container has been filled to a set level; and

at least two sensors, a first sensor detecting when the vessel is nearly filled with chemical and a second sensor detecting when the vessel is completely filled with chemical;

wherein at least the second sensor is mounted on the constricted fill tube so as to provide amplified chemical fluid level information to the second sensor; and

wherein fluid flow into each of the metered vessels is controlled in response to signals from the sensors, an adjustable valve included on each of the intake lines responding to signals from the sensors, the valve adjusting the rate of chemical flow into the metered vessel so as to restrict chemical intake after chemical level has reached the first sensor and to cease chemical intake after chemical level has reached the second sensor, assuring precise cessation of chemical flow into the metered vessels at a predetermined volume.

2. The apparatus of claim 1 wherein a further sensor is provided on the vent tube to cease chemical flow if chemical overfills the vent tube.

3. The apparatus of claim 1 which further comprises a mix tank on the dispense line to provide for mixing of the chemicals from each of the meter vessels prior to delivery to the down-stream facility.

4. The apparatus of claim 3 wherein the mix tank is provided with means to regulate the temperature of the chemicals in the tank.

5. The apparatus of claim 4 wherein the means to regulate the temperature of the chemicals comprises heat exchange coils surrounding the mix tank.

6. The apparatus of claim 1 which further comprises a pressurized gas system in communication with the metered vessels to motivate chemical from the metered vessel to the down-stream facility.

7. The apparatus of claim 1 wherein the down-stream facility comprises at least one storage container.

8. The apparatus of claim 3 wherein the down-stream facility comprises at least one end-use station.

9. The apparatus of claim 1 wherein the two sensors are mounted on the fill tube, the first sensor, indicating when chemical has initially entered the fill tube, and the second sensor, indicating when the fill tube is filled with chemical.

10. The apparatus of claim 9 wherein precision volume adjustment apparatus is provided on each of the metered vessels to assist in calibrating the exact volume of the vessels.

11. The apparatus of claim 10 wherein the precision volume adjustment apparatus comprises a positive displacement element slidably connected to the metered vessel to modify the available liquid volume within the vessel.

12. The apparatus of claim 10 wherein the precision volume adjustment apparatus comprises the constricted vent tube mounted in sliding relationship with the container to control the level at which chemical begins to enter the vent tube.

13. The apparatus of claim 9 wherein the metered vessel includes a low-level sensor to indicate when the metered vessel has been evacuated of chemical.

14. The apparatus of claim 1 wherein the adjustable valve comprises

multiple flow paths, with a separate valve element controlling chemical flow through each of the flow paths;

and

wherein one of the flow paths is constricted so as to limit the rate of chemical flow therethrough.

15. The apparatus of claim 1 which further comprises

a vacuum system in communication with at least one of the metered vessels;

a pressure system in communication with at least one of the metered vessels;

wherein chemical is drawn into the metered vessel by establishing a negative pressure in the vessel through use of the vacuum system, and chemical is dispensed from the metered vessel by applying pressure to the vessel through use of the pressure system.

16. The apparatus of claim 15 wherein a zero pressure box is provided in communication with the metered vessel to provide an area for safe venting of vacuum and pressure from the metered vessel.

20. The apparatus of claim 1 wherein the mix tank includes means to regulate the temperature of the chemicals in the tank, including heat exchange coils.

17. Apparatus for accurately measuring and combining chemicals which comprises:

at least one metered vessel in fluid communication with at least one bulk source of chemicals, by at least one intake line the metered vessel comprising;

a container of predetermined volume;

at least one constricted vent tube, which constricted vent tube is filled once the container has been filled to a set level; and

at least two sensors, a first sensor detecting when the vessel is nearly filled with chemical and a second sensor detecting when the vessel is completely filled with chemical;

a dispense line providing fluid communication between the metered vessel and a down-stream facility;

wherein at least the second sensor is mounted on the constricted vent tube so as to provide amplified chemical fluid level information to the second sensor; and

wherein fluid flow into the metered vessel is controlled in response to signals from the sensors, an adjustable valve included on said at least one intake line responding to signals from the sensors, the valve adjusting the rate of chemical flow into the metered vessel so as to restrict chemical intake after chemical level has reached the first sensor and to cease chemical intake after chemical level has reached the second sensor, assuring precise cessation of chemical flow into the metered vessel at a predetermined volume.

18. The apparatus of claim 17 wherein the down-stream facility comprises a mix tank.

19. The apparatus of claim 17 wherein

the metered vessel includes multiple constricted vent tubes and at least two sensors associated with each constricted vent tube, each constricted vent tube set at a different height within the vessel;

the metered vessel is in fluid communication with multiple bulk sources of chemicals via multiple corresponding intake lines, the flow from each of the bulk sources being monitored by one of the constricted vent tubes and its associated sensors; and

wherein fluid flow into the metered vessel from each of the bulk sources is controlled in response to signals from the associated sensors on the constricted vent tube corresponding to the bulk source, the adjustable valve included on each of the corresponding intake lines responding to signals from the sensors, the valve adjusting the rate of chemical flow into the metered vessel so as to restrict chemical intake after chemical level has reached the first sensor and to cease chemical intake after chemical level has reached the second sensor, assuring precise cessation of chemical flow into the metered vessel at a predetermined volume.

21. The apparatus of claim 17 wherein the two sensors are mounted on the vent tube, the first sensor, indicating when chemical has initially entered the vent tube, and the second sensor, indicating when the vent tube is filled with chemical.

22. The apparatus of claim 17 wherein the constricted vent tube is mounted in sliding relationship with the container to control the level at which chemical begins to enter the vent tube so as to provide precision volume adjustment of the vessel.

23. The apparatus of claim 17 wherein the metered vessel includes a low-level sensor to indicate when the metered vessel has been evacuated of chemical.

24. The apparatus of claim 17 wherein the adjustable valve comprises:

multiple flow paths, with a separate valve element controlling chemical flow through each of the flow paths; and

wherein one of the flow paths is restricted so as to limit the rate of chemical flow therethrough.