Fluid handling – Systems – With flow control means for branched passages
Reexamination Certificate
1999-07-14
2002-07-09
Fox, John (Department: 3753)
Fluid handling
Systems
With flow control means for branched passages
C285S120100
Reexamination Certificate
active
06415822
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to chemical delivery systems and, more particularly, to modular chemical delivery blocks, systems incorporating modular chemical delivery blocks, and methods relating to modular chemical delivery blocks.
2. Description of the Related Art
Chemical delivery systems are used in numerous industries to control the flow of fluids, including gas reactants and other chemicals (e.g., liquids). One industry that heavily relies on chemical delivery systems is the semiconductor processing industry. In semiconductor processing, these systems are commonly used to control the flow of gases to and from processing chambers. Such processing often makes demanding requirements of chemical delivery systems. In chemical etch processes, for example, gas lines usually must be periodically changed out because of line corrosion and/or partial or complete system reconfiguration during maintenance. To minimize the downtime of the etch tool to which a chemical delivery system is attached, the gas lines of the chemical delivery system should be capable of quick removal and replacement.
Conventional chemical delivery systems, however, often fail in this regard.
FIG. 1
shows a conventional chemical delivery system
100
configured to supply gases to an etch process tool used in semiconductor fabrication. Gas paths are provided in system
100
using stainless steel conduit or tubing paths
102
(typically ¼″O.D., ⅜″ O.D., or
½″ O.D.), which are welded between each gas controlling component 104. Because of the configuration of system 100, the time required to change-out or repair components 104 is too long and the cost to reconfigure conduit (tubing) paths 102 is too high.
To overcome the problems of conventional welded tubing designs, modular chemical delivery blocks may be used. Modular chemical delivery blocks are substrates onto which a chemical control component can be mounted. The blocks can then be directly attached to each other, eliminating the need for welded fittings. By using modular chemical delivery systems that incorporate modular blocks and components, not only can worn components be more easily replaced, but the gas delivery system design also can be more readily reconfigured.
But many designs for modular chemical delivery systems are not, however, without their own deficiencies. For example,
FIG. 2
shows a modular chemical delivery system in which individual modular blocks
112
are fastened together with horizontal, full length bolts
114
,
130
throughout an entire modular block assembly
110
. While allowing for rather quick assembly (typically only two 2-inch bolts per axial connection), this design raises several safety, disassembly and repair concerns.
One problem with the design shown in
FIG. 2
is that when full length bolts
114
are subjected to the torque required to provide appropriate sealing integrity between the sealing joints
118
, the deflection of full length bolts
114
is too great. Effectively, the basic deflection force of a bolt
12
can be calculated with the following formula: DEFLECTION=PL/AE, wherein P is the amount of force load upon an axial connection of any adjoining blocks
112
in series (the deflection potential), L is the length of bolt
114
, A is the cross-sectional area of bolt
114
, and E is the modulus of elasticity of bolt
114
based on its material composition. If it is assumed that all equipment suppliers of such modular block technology use
300
series or better materials for the fastener components, then E is a constant for any length bolt
114
. Likewise, in these types of modular gas system designs a designer is often mechanically constrained to using fastener diameters of ¼″ (6.35 mm) or smaller, and thus A can be considered relatively constant. In summary, if A and E are constant, then as the designer increases the length L of the bolt
114
, there will be a corresponding linear increase in the deflection force of the bolt
114
which is conveyed to the fastened substrate joints. If the deflection force is high enough, the seat integrity at the axial joint-to-joint) connections
118
could be lost. As might be expected, such a loss of integrity could be extremely dangerous, especially when toxic chemicals are being delivered.
Another concern with the extended length fastener design shown in
FIG. 2
is related to the manner in which bolts
114
fasten blocks
112
together. If a user were to require removal of any block
112
in modular block assembly
110
, then the respective sealing joints
118
throughout block assembly
110
would be exposed to atmosphere. Such exposure potential raises, among other things, safety and contamination issues with corrosive and toxic chemical delivery applications.
FIGS. 3A and 3B
are cross-sectional and top views, respectively, of another modular block design in which the individual blocks
122
are fastened together via localized bolting at each block-to-block or axial joint connection
124
to form a modular block assembly
120
. Modular block assembly
120
is then connected to mounting brackets
126
. This design dramatically reduces or eliminates the concern for deflection potential by localizing fastener sealing strength, integrity, and length. Use of such a localized fastener design also reduces the number of sealing joints
128
exposed to atmosphere when any given block
122
is removed.
However, the design shown in
FIG. 3A
also has a limitation regarding disassembly. As shown in
FIG. 3B
, if a user were to place multiple modular block assemblies side-by-side (typically on 1.6″ (40.64 mm) to 2″ (50.8 mm) spacing), many of the axial fasteners
130
could not be accessed because the fastener locations lie under the top accessible surface of the blocks (i.e., the collective surface of a modular block that may be accessed from directly above the modular block). Consequently, if the removal of a given modular block is desired, then the modular blocks adjacent to that modular block may undesirably have to be removed first.
Therefore, it would be desirable to design a modular chemical delivery block in which connection locations for allowing the modular chemical delivery block to be coupled to a laterally adjacent chemical delivery block were not obstructed by other portions of the modular block. It would also be advantageous to design a modular chemical delivery system in which localized fasteners connecting laterally adjacent modular blocks were not prevented from being accessed from directly above the top surface of the modular blocks connected by the fasteners. Such a system could allow the flow paths provided by the modular blocks to be more easily and rapidly reconfigured than in other chemical delivery systems.
The above-described information is not admitted to be prior art by its presence in this Background section.
SUMMARY
The problems described above are in large part addressed by a top-accessible modular chemical delivery block configured to direct fluid flow therethrough. Broadly speaking, a top-accessible modular block is one that may be coupled to or decoupled from an adjacent modular block using access from directly above the top-accessible modular block. In a preferred embodiment, the top-accessible modular chemical delivery block includes an axial connection location configured to allow the modular block to be coupled to a laterally adjacent modular block. The interior surface of the axial connection location is preferably substantially parallel to the exterior surface of the axial connection location and unobstructed by other portions of the modular block from the top surface of the modular block. This configuration preferably allows the axial connection location to be accessed from directly above the modular block.
A top-accessible modular block may provide several advantages when incorporated in a modular chemical delivery system. For instance, a top-accessible modular block preferably affords easy access to an axial connecti
Conley Rose & Tayon PC
Fox John
Kowert Robert C.
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