Work holders – Relatively movable jaws – Means to actuate jaw
Reexamination Certificate
1999-02-16
2001-03-06
Scherbel, David A. (Department: 3723)
Work holders
Relatively movable jaws
Means to actuate jaw
C029S234000
Reexamination Certificate
active
06196535
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an apparatus and method for applying force to an object or group of objects. More particularly, it pertains to a device for applying a repeatable and precise clamping force to a series of fluidic blocks.
BACKGROUND OF THE INVENTION
In manufacturing semiconductors, impurities are sometimes introduced to the semiconductor base material through a process known as “doping.” Doping permits the fabrication of n-type or p-type semiconductors with varying degrees of conductivity. In general, the greater the extent of doping, the higher the conductivity of the semiconductor device.
Dopants are often introduced to the process in the form of gases. These gases are used to deposit or remove materials on the surface of the semiconductor device in order to provide insulating regions and connective features required by the semiconductor architecture. The gases used during these processes include, among others, HCl, HBr, tungsten hexafluoride, and silane. These gases are extremely toxic and/or corrosive and/or pyrophoric (i.e., may explode or burn upon contact with an oxidizer such as room air), and therefore must be carefully controlled and contained within gas conduit systems that are leakproof.
When dealing with these semiconductor gas conduit systems, it is advantageous to minimize the area contacted by the gases (the “wetted surface area”) so as to reduce or minimize contamination of the gases. Contamination typically occurs as a result of water vapor which desorbs from the surfaces of the gas conduit and control components. This contamination is typically introduced at the time of installation or following maintenance operations that expose the wetted surface areas to air.
Furthermore, because welded surfaces alter the surface chemistry and have an inherent propensity to corrode, it is advantageous to minimize the number and size of welded surfaces within the gas conduit system.
One method of achieving the dual objectives of reducing surface area and reducing the number and size of welded surfaces is described in U.S. Pat. No. 5,836,355 issued to Markulec et. al. on Nov. 17, 1998. The '355 patent relates to an integrated gas conduit system or “gas panel” which includes a series of linear assemblies each comprising a plurality of interconnected, discreet blocks. The blocks are coupled such that one or more ports within each block is in fluid communication with one or more ports of another block or blocks such that a pressurized fluid may flow therebetween. Metal gaskets disposed between the blocks and around the ports form an effective seal, thus containing the fluids therein. Threaded rods or bolts passing longitudinally through the blocks secure each linear assembly.
While the '355 patent provides a gas panel which minimizes welds and wetted surface area, the discreet blocks that make up the panel must be precisely aligned in order to prevent leakage. Referring to
FIG. 9
, the gas panel is comprised of two layers of linear block assemblies
600
and
700
, one layer oriented transversely to the other. One or more discreet blocks
601
may have porting to not only adjacent blocks
602
,
603
within the linear assembly, but also to other blocks
701
mounted transversely thereto. In order to ensure effective sealing at all interfaces, it is critical that the individual linear assemblies
600
, each comprised of a plurality of blocks, ports
605
, metal gaskets
604
, and bolts
606
(the latter required to compress and seal the blocks and gaskets), be aligned precisely not only along their longitudinal or “x” axis but transversely as well (the “y” and “z” axes). Each block of each linear assembly
600
is dimensionally similar such that alignment of the outside surfaces
607
ensures alignment of the internal porting
605
.
Many times the blocks are difficult to align and, unfortunately, even slight misalignment can result in gasket leakage. For example, if two adjacent blocks
601
and
602
of the linear assembly
600
are misaligned along the z axis by 0.005 inches and the assembly
600
is subsequently bolted to the two blocks
701
and
702
of two transverse assemblies
700
, the act of bolting the blocks
601
and
602
to the assemblies
700
(using the bolts
608
) will force the lower faces of the blocks
601
and
602
to the mating faces of the blocks
701
and
702
respectively. Due to the misalignment between the blocks
601
and
602
, a shear strain on the metal gasket between those blocks will develop. When metal gaskets of this type are sheared, seal integrity is sacrificed. The effects of even partial seal failure include: compromising the semiconductor process; damaging gas system components; and potentially inflicting serious injury or even death to system operators.
Accordingly, a clamping device that can precisely align the blocks in the y and z directions is advantageous to produce these linear assemblies. At the same time, the device must permit relative motion between the blocks of the linear assembly (i.e., in the x direction) so that they may draw together and compress the metal gaskets. Currently available alignment methods use various devices to clamp the blocks between two faces before bolting. These devices, however, do not always produce a repeatable clamp force. If the clamp force exerted on the blocks is not repeatable, the frictional forces between the blocks and the clamp are likewise not repeatable. If the clamp force is too high, the frictional forces on the blocks will prevent the blocks from drawing together and forming a hermetic seal. If the clamp force is too low, the act of torquing the bolts
606
will induce a torsional moment into the linear assembly, resulting in sheared gaskets and misaligned blocks. Unfortunately, the need to minimize the frictional forces on the blocks is at odds with the need to sufficiently restrain the blocks during torquing.
Another problem with conventional clamping devices is that the clamp devices have only one point of loading. Thus, if the blocks are placed off-center from the loading point, the clamping faces will become skewed (i.e., not parallel). This will also produce a variation in the clamp load applied and adversely impact alignment and sealing.
Accordingly, what is needed is a way to apply a consistent and predictable clamping force to a group of objects while maintaining precise alignment therebetween. What is further needed is a device that can apply such a clamping force without overly restricting relative motion of the objects transverse to the clamping force.
SUMMARY OF THE INVENTION
A precision clamping device and method is disclosed. In one embodiment, the precision clamping device comprises: a first clamp face; a second clamp face, the second clamp face in an opposing, substantially parallel relationship to the first clamp face; a displacing mechanism adapted to move the first clamp face toward the second clamp face, wherein the second clamp face remains substantially parallel at all times to the first clamp face; and a biasing mechanism coupled to the displacing mechanism, wherein the biasing mechanism is adapted to provide a substantially repeatable clamp force to an object or group of objects placed between the first clamp face and the second clamp face.
The method for assembling a plurality of objects is also disclosed comprising, in one embodiment: placing a plurality of objects onto a surface of a clamping device between a first clamp face and a second opposing and substantially parallel clamp face; actuating a displacing mechanism, thereby displacing the first clamp face towards the second clamp face; contacting the objects between the first clamp face and the second clamp face; and biasing the first clamp face toward the second clamp face, thereby applying a uniform clamping force to the objects.
In another embodiment, the device comprises a fixed jaw having a first clamp face; a movable jaw having a second opposing clamp face substantially parallel to the first clamp face, the movable jaw adapted to move in
Scherbel David A.
Schwegman Lundberg Woessner & Kluth P.A.
Shanley Daniel
Talon Engineering Corp.
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