WO2000063757A1

WO2000063757A1 - Modular surface mount mass flow and pressure controller

Info

Publication number: WO2000063757A1
Application number: PCT/US2000/010041
Authority: WO
Inventors: Anthony C. Diprizio; Kevin T. Mahan; Jon M. Sutton; Maura I. Toth
Original assignee: Millipore Corp
Current assignee: EMD Millipore Corp
Priority date: 1999-04-19
Filing date: 2000-04-13
Publication date: 2000-10-26
Anticipated expiration: 2001-10-19
Also published as: TW434379B; AU4459700A

Abstract

A modular surface mount mass flow and pressure controller of the present invention includes a modular flow sensor and a modular control valve. The modular flow sensor measures the amount of gas flowing through a modular gas stick and the modular control valve adjusts and controls the flow rate of gas through the modular gas stick. Both the modular flow sensor and the modular control valve are mounted on a surface of a modular base.

Description

MODULAR SURFACE MOUNT MASS FLOW AND PRESSURE CONTROLLER

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to gas transport systems and measuring devices, and more particularly to a system and method for integrating various components m a modular gas transport system, and even more particularly to the integration of gas flow components m a modular gas stick for use m semiconductor manufacturing.

BACKGROUND OF THE INVENTION

Many of today' s manufacturing processes require the delivery of gases through a gas flow path having a number of components used to regulate, filter, and monitor the gas flowing through the path. For example, current semiconductor manufacturing processes, such as chemical vapor deposition, require the delivery of ultra-pure gases at proper flow rates and amounts to process chambers within a tool. A number of gas components are typically incorporated into the gas path (commonly referred to for semiconductor manufacturing processes as the gas stick) , including mass flow controllers, flow monitors, moisture monitors, valves, regulators, gas filters, gas purifiers, pressure sensors, diffusers, capacitance diaphragm gauges, displays, pressure transducers, and other commercially available components .

An exemplary prior art gas path 10, or gas stick, is shown m FIGURE 1. In FIGURE 1, the gas will flow from a source through gas path 10 that can include, as an example, an isolation valve 12, a regulator 14, a pressure transducer or sensor 16, a filter 18, an isolation valve 20, a mass flow controller 22, and a downstream isolation air operated valve 26 to the process chamber (not shown) . Each individual gas component is a stand alone unit and is connected to the next using a series of m-line connectors 24. This is an exemplary manuf cturing system and any number of additional and alternative components could comprise the gas path from the source to the process chamber. However, adding gas components to an in- line gas stick 10 increases the overall length of the gas stick 10 by both the component length and the connector length.

Another problem with current gas sticks is that the mass flow controller 22 is typically built only to operate within a limited range of flow and pressure conditions for a specific gas. To operate outside the original parameters, the sensor portion of the mass flow controller 22 may be recalibrated or re-ranged, but the attached control valve may no longer be capable of acceptable performance under the new conditions (pressure, flow, or gas type) . Thus the permutations of calibrated mass flow controllers needed can be costly. As many as fifty to two hundred different mass flow controllers may be needed to cover every different permutation m a typical semiconductor manufacturer scenario.

Mass flow controllers within current gas sticks are typically either thermal-based instruments or pressure- based instruments. The whole mass flow controller unit must be replaced to convert the current gas sticks from a thermal-based to pressure-based flow control. This too can be very costly.

Recently, the semiconductor industry began moving to a modular gas stick that uses a standard footprint. The standard footprint for the modular gas stick is approximately 1.5 X 1.5 inches, according to SEMI Draft

Doc. 2787.1 (as shown m FIGURE 4) . Certain gas components may not fit the 1.5 X 1.5 inch modular footprint of the modular gas stick. For example, the base dimensions of the standard mass flow controller 22 shown m FIGURE 2 are approximately 4 X 1.5 inches (dimension A = 4 inches, dimension B = 1.5 inches) . This does not the fit the 1.5 X 1.5 inch modular foot print of the modular gas stick.

SUMMARY OF THE INVENTION The present invention provides an improved gas component integration system and method that substantially eliminates or reduces disadvantages and problems associated with previously developed gas flow path systems and methods used for flowing a gas from a source, through a number of components, to a destination.

More specifically, the modular surface mount flow sensor and control valve of the present invention provides a way integrating the mass flow controller 22, such as the one shown m FIGURE 1 into a modular gas stick. In a modular format, the gas components stack m a direction perpendicular to the original gas flow axis. The gas components can be individually manufactured components that are connected together using standard VCR connections or SEMI Draft Doc. 2787 specification connections. A specific embodiment of the present invention is the modular surface mount mass flow and pressure controller. The modular surface mount mass flow and pressure controller of the present invention includes a modular flow sensor and a modular control valve. The modular flow sensor measures the amount of gas flowing through a modular gas stick and the modular control valve adjusts and controls the flow rate of gas through the modular gas stick. Both the modular flow sensor and the modular control valve are mounted on a surface (e.g., the top) of a modular base. The present invention provides an important technical advantage by providing a way to incorporate the functionality of a mass flow controller m a modular gas stick design.

The present invention provides another technical advantage by providing easy repair and replacement of the modular gas components which make up the mass flow controller, thus reducing associated costs.

The present invention provides another technical advantage by reducing the number of permutations of current mass flow controllers required to handle all the different ranges of different types of gases used in the semiconductor manufacturing process .

The present invention provides another technical advantage by providing more flexibility in placing gas components in a gas stick design.

The present invention provides another technical advantage by providing a way to easily convert from a thermal -based gas stick design to a pressure-based gas stick design and visa versa. The present invention provides another technical advantage by providing a gas stick design where the electronics can either be remote or local . BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings m which like reference numerals indicate like features and wherein:

FIGURE 1 shows a prior art gas flow path having a series of individual, single function gas components, including a mass flow controller, connected together inline along the axis of gas flow;

FIGURE 2 shows the base dimensions of a prior art mass flow controller; FIGURE 3 shows one embodiment of the present invention where the mass flow controller has been broken down into a modular flow sensor and a modular control valve;

FIGURE 4 shows the base dimensions of the modular flow sensor and modular control valve; FIGURE 5 shows the modular gas stick m a thermal - based flow configuration; and

FIGURE 6 shows the modular gas stick m a pressure- based flow configuration.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention are illustrated m the FIGURES, like numerals being used to refer to like and corresponding parts of the various drawings.

The modular surface mount mass flow and pressure controller of the present invention includes a modular flow sensor and a modular control valve . The modular flow sensor measures the amount of gas flowing through a modular gas stick and the modular control valve adjusts and controls the flow rate of gas through the modular gas stick. Both the modular flow sensor and the modular control valve are mounted on a modular base.

The connections used to mount the modular flow sensor, modular control valve, and other gas components on the modular base can include connectors that meet the draft SEMI 2787 specification (described m SEMI Draft Doc. 2787, incorporated herein by reference) such as B-seal, C-seal, CS-seal, W-seal and Z-seal connectors. Examples of the modular gas components that can be mounted on a modular base include gas filters, gas purifiers, pressure transducers, mass flow controllers, displays, moisture monitors, gauges, valves, diffusers, capacitance diaphragm gauges, and pressure regulators. The present invention includes separating the flow sensor and control valve of a standard mass flow controller and mounting them on a modular base. It should be understood that while the multi-functional gas components of the present invention will be further illustrated and described using the specific application of a semiconductor gas stick, the system and method of separating the flow sensor and control valve and mounting them on a modular base can be applied to other gas flow paths .

FIGURE 3 shows one embodiment of a modular gas stick 10 as opposed to the conventional in-line gas stick 10 of FIGURE 1. The modular gas stick 10 fits onto a modular base 38 that meets SEMI 2787 specifications for modular gas sticks (including height, length, and width requirement) . In FIGURE 1, the m-line gas stick 10 was configured such that the gas components required a connector 24 before and after each gas component . The base block of the standard mass flow controller 22 shown m FIGURE 1 is typically more than twice as long as other gas components m the gas stick 10. The base block dimensions of a typical prior art flow controller are 4 X 1.5 inches, as shown in FIGURE 2. This is much larger than the modular footprint dimensions of 1.5 X 1.5 (shown m FIGURE 4) inches required to fit on the modular base 38. Thus, the prior art mass flow controller 22 of FIGURE 1 simply cannot be mounted onto a modular base

As shown m FIGURE 3, the present invention provides a separate flow sensor 25 and control valve 30 which make up the prior art features of mass flow controller 22 and mounts them on modular base 38. This results m a reduction m horizontal space along the axis of gas flow

28. The flow sensor 25 and control valve 30 of the present invention each fits the 1.5 X 1.5 inch modular foot print shown m FIGURE 4 (dimension C equals approximately 1.5 inches) . Seating a modular flow sensor 25 and modular control valve 30 allows the use of a modular base block 38. Furthermore, the length of the gas stick 10 has been reduced because the standard mass flow controller 22 base block requires 4 inches, while the combined length of the flow sensor 25 and control valve 30 base blocks is only 3 inches. This will save horizontal space along the gas flow path 28 as well as provide a number of other advantages .

Typically, the standard mass flow controller 22 of FIGURE 1 is built only to operate within a limited range of flow and pressure conditions for a specific gas. To operate outside the original parameters, the sensor portion of the mass flow controller 22 would have to be recalibrated or re-ranged, but the attached control valve may no longer be capable of acceptable performance under the new conditions (pressure, flow, or gas type) . Thus the permutations of calibrated mass flow controllers needed can be costly. The present invention eliminates the need to recalibrate, re-range, or completely replace the standard mass flow controller 22 in many instances. The separated flow sensor 25 may work over a range of 5 to 6 different gas types having different densities or different thermal conductivities. Similarly, the separated control valve 30 may work over a range of 5 to 6 different ranges. By using different combinations of the flow sensor 25 and control valve 30, one may be able to cover the 50 to 200 other permutations that a standard mass flow controller 22 has to be built to. Also, if either the flow sensor 25 or control valve 30 breaks down, either part can be replaced at a lower cost than having to replace the whole standard mass flow controller 22.

The present invention provides another major advantage by providing more flexibility in placing individual gas components at different locations along the gas stick. For example, there are certain types of gasses which present problems to standard mass flow controllers 22 which are calibrated for thermal-based flow measurements. Other gasses present problems to standard mass flow controllers 22 which are calibrated for pressure-based flow measurements. In situations when use of a particular gas requires changing from a thermal-based mass flow controller to a pressure-based mass flow controller (or visa versa) , the entire standard mass flow controller 22 must be replaced. The need to replace the entire mass flow controller 22 is eliminated m the present invention due to the use of separate, modular flow sensors 25 and control valves 30. If the gas flowing through the gas stick 10, or the process requires a thermal based measurement, a thermal flow sensor can be mounted on the modular gas stick 10. If the gas flowing through the modular gas stick 10, or the process requires a pressure-based measurement, a pressure- based flow sensor can be mounted on the gas stick 10. The control valve 30 need not be replaced to convert the modular gas stick from a thermal -based measurement gas stick to a pressure-based measurement gas stick. As with existing mass flow controllers, the electronics controlling the flow sensor 25 and the control valve 30 can be either remote or local .

FIGURE 5 shows one embodiment of the modular gas stick 10 m a thermal-based measurement configuration. In FIGURE 5, the flow sensor 25 is a thermal-based flow sensor and is preferably placed immediately before the control valve 30 along the gas flow path 28. The electronics controlling modular flow sensor 25 and modular control valve 30 can be remote or local. To convert the modular gas stick 10 from a thermal-based measurement configuration to a pressure- based configuration, first remove the thermal flow sensor 25 and the control valve 30. Next, place the control valve 25 m the position where the thermal flow sensor 25 used to be. Finally, place a pressure-based flow sensor 25 m the position where the control valve 30 used to be. The pressure-based configuration of the modular gas stick 10 can be seen m FIGURE 6. In FIGURE 6, the control valve 30 is preferably placed before the pressure-based flow sensor 25 along the gas flow path 28. Since only the flow sensor 25 needs to be replaced when converting the modular gas stick 10 from a thermal -based measurement configuration to a pressure-based configuration, the replacement part cost is reduced.

In summary, the modular surface mount mass flow and pressure controller of the present invention includes a modular flow sensor and a modular control valve. The modular flow sensor measures the amount of gas flowing through a modular gas stick and the modular control valve adjusts and controls the flow rate of gas through the modular gas stick. Both the modular flow sensor and the modular control valve are mounted on a modular base.

Although the present invention has been described in detail herein with reference to the illustrative embodiments, it should be understood that the description is by way of example only and is not to be construed in a limiting sense. It is to be further understood, therefore, that numerous changes in the details of the embodiments of this invention and additional embodiments of this invention will be apparent to, and may be made by, persons of ordinary skill in the art having reference to this description. It is contemplated that all such changes and additional embodiments are within the spirit and true scope of this invention as claimed below.

Claims

WHAT IS CLAIMED IS:

1. A modular surface mount mass flow and pressure controller comprising: a modular flow sensor operable to measure the amount of gas flowing through a modular gas stick; a modular control valve operable to adjust and control the flow rate of gas through a modular gas stick; and a modular base, said modular flow sensor and said modular control valve are mounted on a surface of said modular base.

2. The surface mount mass flow and pressure controller of claim 1, wherein said modular flow sensor can be a modular thermal -based flow sensor or a modular pressure-based flow sensor.

3. The surface mount mass flow and pressure controller of claim 1, wherein said modular flow sensor is a modular thermal -based flow sensor that is positioned prior to said modular control valve to form a thermal -based mass flow configuration such that said gas flows through said modular thermal -based flow sensor before flowing through said modular control valve.

4. The surface mount mass flow and pressure controller of claim 1, wherein said modular flow sensor is a modular pressure-based flow sensor that is placed after said modular control valve to form a pressure-based mass flow configuration such that said gas flows through said modular control valve before flowing through said modular pressure-based flow sensor.

5. The surface mount mass flow and pressure controller of claim 1, wherein said modular flow sensor and said modular control valve have a modular footprint.

6. The surface mount mass flow and pressure controller of claim 5, wherein said modular footprint meets SEMI Draft Doc. 2787.

7. The surface mount mass flow and pressure controller of claim 6, wherein said modular flow sensor and said modular control valve are mounted on said modular base using connectors which meet the SEMI Draft Doc. 2787.

8. The surface mount mass flow and pressure controller of claim 1, wherein said modular flow sensor, and said modular control valve can be interchanged with any other modular component anywhere along said modular gas stick.

9. The surface mount mass flow and pressure controller of claim 1, wherein said modular flow sensor may be easily interchanged with another modular flow sensor having a different measurement range for measuring the flow of gases having different densities or different thermal conductivities .

10. The surface mount mass flow and pressure controller of claim 1, wherein said modular control valve may be easily interchanged with another modular control valve for controlling the flow of gases having different densities .

11. The surface mount mass flow and pressure controller of claim 1, wherein the electronics controlling said modular flow sensor and said modular control valve can be either remote or local .

12. A method of controlling the flow and pressure of a gas through a modular gas stick, comprising the steps of: measuring said gas flowing through said modular gas stick using a modular flow sensor; controlling and adjusting the flow of said gas flowing through said modular gas stick using a modular control valve ; and mounting said modular flow sensor and said modular control valve on a modular base.

13. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, wherein said modular flow sensor can be a modular thermal -based flow sensor or a modular pressure-based flow sensor.

14. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, further comprising the step of mounting said modular flow sensor and said modular control valve in a thermal -based mass flow configuration or a pressure-based mass flow configuration.

15. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, wherein said modular flow sensor is a modular thermal -based flow sensor, and further comprising the step of placing said modular thermal -based flow sensor before said modular control valve such that said gas flows through said modular thermal -based flow sensor before flowing through said modular control valve .

16. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, wherein said modular flow sensor is a modular pressure-based flow sensor, and further comprising the step of placing said modular pressure-based flow sensor after said modular control valve such that said gas flows through said modular control valve before flowing through said modular pressure- based flow sensor.

17. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, wherein said modular flow sensor and said modular control valve each has a modular footprint .

18. The method of Claim 17, wherein said modular footprint meets SEMI Draft Doc. 2787.

19. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, wherein said modular flow sensor and said modular control valve are mounted on said modular base using connectors which meet the draft SEMI 2787 specification, such as B-seal, C-seal, CS-seal, W-seal, and Z-seal connectors.

20. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, wherein said modular flow sensor, and said modular control valve can be interchanged with any other modular component anywhere along said modular gas stick.

21. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, further comprising the step of interchanging said modular flow sensor with another modular flow sensor having a different measurement range for measuring the flow of gases having different densities or different thermal conductivities.

22. The method of controlling the flow and pressure of a gas through a modular gas stick of claim 12, further comprising the step of interchanging said modular control valve with another modular control valve for controlling the flow of gases having different densities.