Fluid handling – Systems – With flow control means for branched passages
Reexamination Certificate
1999-01-13
2002-05-28
Fox, John (Department: 3754)
Fluid handling
Systems
With flow control means for branched passages
C137S597000, C285S124500
Reexamination Certificate
active
06394138
ABSTRACT:
1. Field of the Invention
The present invention is directed to a manifold system for enabling a distribution of fluids and more particularly, to a modular manifold system that is subjectively adaptable to semi-conductor processing equipment to enable a distribution of gases in a semi-conductor manufacturing environment by assembling a plurality of individual manifold blocks into a gas stick.
2. Description of Related Art
Wafer fabrication facilities are commnonly organized to include areas in which chemical vapor deposition, plasma deposition, plasma etching, sputtering and alike are carried out. In order to carry out these processes, it is necessary for the tools and machines that are used for the processes to be provided with a precise amount of processing gases to enable the fabrication steps. These gases can be inert, reactive, or can provide reactive species as desired by the particular manufacturing process.
For instance, in order to perform epitaxial deposition, silicon tetrachloride has bubbled through it a carrier gas such as dry nitrogen, which then carries silicon tetrachloride vapor into an epitaxial deposition chamber. In order to deposit a silicon oxide dielectric coating, also known as a deposited oxide coating, silane (SiH
4
) is flowed into the tool and oxygen is flowed into the tool where they react to form (SiO
2
) on the surface of the wafer. Plasma etching is carried out by supplying carbon tetrachloride and sulfur hexafluoride to a plasma etcher tool. The compounds are ionized, to form reactive halogen species which then etch the silicon wafer. Silicon nitride may be deposited by the reaction of dichlorosilane and ammonia in a tool. It may be appreciated that in each instance pure carrier gases or reactant gases must be supplied to the tool in contaminant-free, precisely metered quantities.
In a typical wafer fabrication facility, the inert and reactant gases are stored in tanks which may be located in the basement of the facility and which are connected via piping or conduit to a valve manifold box. The tanks and the valve manifold box are considered to be part of the facility level system. At the tool level, an overall tool system, such as a plasma etcher or the like, includes a gas panel and the tool itself. The gas panel contained in the tool includes a plurality of gas paths having connected therein active components such as manual valves, pneumatic valves, pressure regulators, pressure transducers, mass flow controllers, filters, purifiers and the like. All have the purpose of delivering precisely metered amounts of pure inert or reactant gas from the valve manifold box to the tool itself.
The gas panel is located in the cabinet with the tool and typically occupies a relatively large amount of space, as each of the active devices are plumbed into the gas panel, either through welding tubing to the devices or combinations of welds and connectors such as VCR connectors available from Cajon Corporation or the like.
Gas panels are relatively difficult to manufacture and hence expensive. In a combination VCR connector and welded tubing system, the individual components are held on shimmed supports to provide alignment prior to connections at VCR fittings. Misalignment at a VCR fitting can result in leakage.
In addition, it has been found that VCR fittings often tend to come loose in transit and some gas panel manufacturers assume that the VCR fittings have loosened during transit, possibly admitting contaminants to the system.
Welds are relatively expensive to make in such systems but are typically carried out using a tungsten inert gas (TIG) system, having an orbital welding head to weld a tube stub and a tube together. The welding must take place in an inert atmosphere, such as argon, and even then leads to deterioration of the surface finish within the tubes. One of the important characteristics of modem-day gas panel systems and gas handling systems is that the surfaces of the gas handling equipment that tend to have the gas or vapor contact them must be made as smooth and nonreactive as possible in order to reduce the number of nucleation sites and collection sites where contaminants may tend to deposit in the tube, leading to the formation of particulates or dust which could contaminate the wafers being processed.
Additional problems with conventional gas panels relate to the fact that a combination VCR and welded system of the type currently used today typically requires a significant amount of space between each of the components so that during servicing the VCR connections can be accessed and opened. In addition, in order to remove an active component from a contemporary gas panel, many of the supports of the surrounding components must be loosened so that the components can be spread out to allow removal of the active component under consideration.
Most wafer fabricators are aware that it is only a matter of time until, for instance, the silane lines in the gas panels are “dusted.” “Dusting” occurs when air leaks into an active silane line causing a pyrophoric reaction to take place yielding loose particulate silicon dioxide in the tube, thereby contaminating the line. Other lines also can be contaminated. For instance, those which carry chlorine gas used in etchers or which carry hydrogen chloride used in other reactions. Hydrogen chloride mixing with moisture present in the humidity of air produces hydrochloric acid which etches the interior of the tube, roughening it and increasing the number of nucleation sites and the likelihood that unwanted deposits would occur inside the tube. In both of these cases, as well as in others, it would be necessary then to open the particular line in the gas panel in order to clean it. In addition, individual component failures may require a line being opened in order to clean it and is time consuming and expensive.
Examples of fluid distribution systems can be found in not only the semi-conductor field but in other fields such as biochemical-related industries. U.S. Pat. No. 5,653,259 discloses the use of a particular form of manifold block and valving system with a saw tooth design of a common fluid passageway. U.S. Pat. No. 4,168,724 discloses a manifold block having a common conduit line that can be connected to appropriate valve members.
U.S. Pat. No. 3,384,115 discloses the mounting of pneumatic logic systems on a common manifold block. U.S. Pat. No. 4,181,141 discloses a pneumatic control circuit that permits a sequential connection of modules by the use of cylindrical connector plugs.
U.S. Pat. No. 4,352,532 discloses a manifold system that can detachably carry a plurality of pneumatically and electrically operated control units. Likewise, U.S. Pat. No. 4,093,329 discloses a manifold assembly with a plurality of property control units. PCT Publication No. WO98/25058 discloses a gas panel with a plurality of interconnected discrete blocks. U.S. Pat. No. 4,524,807 discloses a snap-together modular manifold construction. U.S. Pat. No. 3,025,878, U.S. Pat. No. 4,921,072, U.S. Pat. No. 5,662,143, U.S. Pat. No. 5,178,191, and PCT publication No. WO 95/10001 are cited of general interest.
The prior art is still seeking to optimize the delivery of fluids such as gas to semi-conductor manufacturing equipment and it is desirable to provide surface mount gas delivery systems that will permit standardized component interfaces that can be easily sealed and removed, thereby obtaining an economy of scale.
BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS
The present invention is designed to provide a manifold system for enabling the distribution of fluids such as semi-conductor processing gases and to provide an improved surface mount gas delivery system that will enable a standardization of the interface of active components. With standardized component interfaces, the production, distribution, and factory and field inventories of gas delivery components can be minimized and it will be possible to have an economy of scale while still permitting a subjective design to meet the demands of the customer.
The present inventi
Redemann Eric J.
Sherriff David P.
Vu Kim N.
Fox John
Unit Instruments, Inc.
Wolf Greenfield & Sacks P.C.
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