Note: Descriptions are shown in the official language in which they were submitted.
DI
F~ld o.f tne Invention
This invention reldt~ to a dispos~bl~ c~n-tainer
for shipping toxic and corrosive liquid ch~ic~ls. In
particul2r, khis invention r~ es to a con~ainer for
transporting ultra hi~h-p~rlty ll~uid chemlc~ls of the
type used, e.g., in the manufacture 9f semicorlductors and
optical fibers.
Bdck~ro~ d of thl? rnv--nt~on
Many manufacturing processes utilize high-purity
cl.emicals ~ntrained in a carrier gas for SL'Ch processes as
~emiconductor doping, vapor deposition, etcl,ing, and
molecular impregnation of a substrate with the entrained
ch~mical. In ma~ly of these applications, the ~urity of
the chemical is critical, and impurities are m~asured in
parts per billion. Contaminatlon, s~ch as that ~hich may
oc~ur during shipping and handling, must be avoided at all
costs.
For example, son,e of the chelllicals used in tl.e
~o m~nufacture of semiconductor devices are liq~id
phvsphorous oxychloride, phosphorous trichlGride,
phosphorus tribrornide, trichloroethyl~ne, tetra-
methoxysilane, silicon tetrabromide, trichloroethane,
arsenic trichloride, arsenic tri~romide, and antimony
pentachloa~ide. Many of these chemicals, such as the
arenic compounds, are highly toxic. Others, such as the
~romine compounds, are extremely c~rrosive. Accordingly,
worker ~posure must be rninimized~ ~t the same tilne, care
must be taken to assure that the highest level of purity
~O of these chemicals is maintained. ~ven the slighte~t
contaminatiorl may affect the yiel~ of se~ conductox~
devices, which directly affects the profitability o~ the
over~ll fabricatlon process.
In the past, such chemicals have typically been
shipped in flame-sealed ~lass ampules capable of meetin~
the pertinent Department of Trallsportation regu]ation
r~quirin~ containers capable of holding .l5 psi pressur~.
tAlthou~h certain n\etal conkainers may also satisfy the
.,
applicable DOT regulations, such containers are
unacceptable because of the problem of metallic
contamin~tion, which is particularly harmful to the
reliable manufacture of semiconductors.) When the glass
contain~rs w~re received, they wer~ t-ypically op~r,~d by
breakiny th~ sea?, aft~r which they were e~ptied into a
bubbler. A bu~bler is ~ device which perlnit~ a carrier
gas, such as nitrogen, to be bubbled through tt,e liquid
source material, ~hereby the liquid source rnaterial
becomes entrain~d in the ~as. The carrier 9dS, with
entrained ch~mical, is typically supplied to the substrate
to ~e treated, e.g., in a diffusion furnace or a vapor
deposition cham~r. As is re~dily apparent, the transfer
of the liquid source material from the glass shipping
ampule to the bubbler was a serious potential source of
atmospheric and molsture contamination and worker exposure
to the chemical.
One relatively satisfactory solution ~o the
contamination and ~xposure problem is th~ quart~ container
~o disclosed, for example, in U.S. Patents 4,134,514,
~,140,735, and 4,298,037. These patents di~clos~
high-purity quart~ bubblers which double as shipping
containers. The quartz bubblers are filled with chemical
by the supplier; the fill tube is flame-~ealed, in
~5 accordance with DOT regulatiors; the bubbler containing
c'-~mical is then shipped to the user, who att~ches g~s
lines, breaks a seal, arld monitors t~e temperature control
equipment to the bubbler, and uses the chelnical as
desired. Although the majority of contamination problems
are thus avoidcd, since there is no need to transfer the
chemical from the shippin~ container into a separate
bubbler, one drawback of this system is the expense
involvedO High purity quartz containers are relatively
` cvstly. For this reason 9 it has been the practice in the
industry to return emp~y quartz bubblers to the chemical
~upplier to be refilled. This involves a return shi pping
expense. Moreover, as the inlet, outlet, and fill tubes
are repeatedly heated and resealed, the crystalline
~ ~ 7~
structure of the qu~rtz can be af~ected, causinq the
quartz to become brittle or crumbl~. As d result, the
bubbler must be carefully examined at e~ch refill time.
Some bubblers can only b~ used as few ~s thr~e times,
others may last for 10 to 12 refills, wi~h the average
belng ln the reighborl~ood of ~ive ~o six tlrl~es.
N~ suitable less costly alternatiYes to the
quartz bubbler has be~n app~r~nt to those of ordin~ry
skill irl the selniconductor and related supporting
industries. ~ost alternatives considered have been ruled
out for failure to satisfy shippins re~ulations,
in~co~l)patibility with the chemicals to be shipped, or
contalnin~tion of those chemicals by the material itself.
A ma;or problem that appears to rule out the use
Of organic polymer materi~ls for bubblers is air ~nd
moisture contamination of the ccntained liquid source
material. Even minute amounts of moisture contaminati~n
can have extremely deleterious effects on semiconductor
yield. ~lthou~h many organic polymtrs are cosTuilonly
believed to be impermeable vapor barriers, in truth, small
~mounts of air and moisture are able to infiltrat~ nearly
all such materials. One graphic illustration of this
phenomenon is the gradual shrinking of a child's balloon
as pressurlzed air escapes through the walls of the
balloon itself.
The current cost of even small (500 ml.)
high-purity quartz bubblers is on th~ order of several
hundred dollars -- o~ten approaching or being more than
the cost of the chemicals they contain. It is significant
that~ de~p~te the existence of the problem for a n~,~er of
years, and the almost overwhelming economic incentive
involved, no s~itable low-cost altern~tive bubbl~r has
heretofore been developed.
~ ccordingly it is an object of khe present
lnvention to provide a relatively inexpensive b~bbler
suit~ble for transporting toxic and corroslve ultra
high-purity liquids. It is ~ furtl er object of the
preser.t invention to provide a disposable bubbler made of
~ ~'7~
C~
organic polyll,er materialO ~nother object of the present
i~vention ls to provide a low-cost bubbler that avoids
atmospheric cont~minatior-, moisture cont~mination, aJld
contamination of the contained liquid source mat~rial by
5 the container itself. Skill ~nother object of the pr~sent
inv~ntion is to provide a valve for use on a bubbler that
is vapor imp~rrn~able, and yet provides no possibility of
metallic contamination of t~,~ liquid source material.
S~n~ary o:~f the Inv~ntlon
lo In further~nc~ of the foregoing object~ there
is provided in accordance with the present invention a
disposable article for shipping a hazardous liquid
material, comprising a container body o s~bstantially
~apor-impermeable organic polymer rnaterial hav~ng a top
and a bottom, a first opening in the to~ of the container,
a tube extending from the first openi~g into the
contuiner, having an open botton~ end near the bottom of
the container, a second opening in the top of the
container, a frangible seal in the first and second
openings fcr sealing the openings, and a vapor-impermeable
metal coating on the outside of the container in incimate
contact with the organic polymer material. The metal
coating is preferably a vapor-deposited coating of
chromium, nickel, or zinc. The organic polymer material
may be any suitable vapor- and moisture-impermeable
~olymer, ~uch as linear ultra-high molecular weight or
high density polyethylene or other polyolefir" a styrenic
polymer, polyethylene terephchalate, melall)ine
formaldehyde, fluoropolymers, chlorGfluoro polymers or
multiple layers of different polymers, such a
polytetrafluoroethylene, polyethylene, polyvinylic~ine
chloride, and the like.
In accordance with another embodiment of the
invention, there i5 disclosed a bubbler corresponding to
the foregoing general description in combination with a
corrosive or toxic liquid chemical.
In accordance w~th still ~nother embodiment of
the present invention, there is disclosed a disposable
..... . ~
article for shipping hazardou~ liquid material, comprising
a cont~iner of substantially vapor-imperme~le organic
polymer m~terlal havlng a top and a bottom, mean~ for
introducing a carrier gas lnto the bottom of ~he
5 container, means for removing carrier gas from the top of
the contain:~, and a vapor-impermeable nletal coatin~
deposited on ~he outside of the orgdnic polym~r material
of the container. The liquid level detector utilizes
either a floating contain~r o~ magnetic material or ~
heater in close proximity to a heat detector, the heat
detector being actu~ted when liquid inside th~ container
is no lon~r pr~sent to conduct hé~t away from the heater
and heat detector.
In accordance with still another aspect of the
present inYention, there is provided a valve on the
container for controlling the flow of carrier gas, or
other ~luid, into or out of the container, the valve
comprising an inlet port, an outlet port, an interior of a
nonreactive organic polymer, silicone~ ~lass, or cer3mic
material, vapor-impermeabl~ seals at the inlet port and
the outlet port, a vapor-impermeable n,~tal on ~he exterior
of the valve ~p to th~ seals, so that the exterior of the
v~l~e, which may experience ambient contdct, is
substantially con,~letely covered with metal and the
interior surfaces of the valve~ which are in cont~ct with
the fluid controlled by the valve, are substantially metal
free.
In yet another embodiment of the presênt
invention, th~re is provided a moisture-impernseable
3~ bubbler havin~ an organic polymer interior and a metl
exterior, and an ultra-hi~h purity liquid chemical inside
the bùbb'er, the organic polymer material being
nonreactive with and noncontaminative of the liquid. A
valve may also be provide~ on the bubblêr hav~n~ a metal
exterior, and an organic polymer interlor that is
nonreactive with and noncontam:lnativ~ of th~ liqui~ in the
bubbler.
In accordanc~ with ~other aspect of the
~ ~7~
invention, a fluld control valv~ is provided with an inlet
port, an outl~t port, a subs~antially me~al-fre~ interior
of or~anic polym~r material defining a fluid passag~-way, a
vapor-impermeable metal exterior, fluid control means
inside the fluid p2ss~geway, means extending frcm t~e
exterior to the interior of the valve for actuating t~i~
fluid control means, and vapor-ilnperrneable seals at the
inlet port, the outlet port, and on the actuating means
which separate the metal exterior from the metal-free
interior, and prevent ambient contact with the interior
~hen the valve is in use. The ~-als may ~e made of an
org~nic fluoropolym~r, a polyolefin, a polyvinyl resin, a
polyamide, or, preferably, graphite.
Brlef D scri~ption f t ~
Figure 1 i~ a partially cutaway perspective view
of a bubbler according to the present invention.
~ igure 2 is an exploded side view of the bubbler
according to the present invention, illustratin~ a
t~-piece construction.
2~ Figure 3 i~ a side view of a vertical cross-
section of a vdlve po~itioned above the seal in the inlet
tube of the bubbler.
Figure 4 is a vertical cross-section of a
rotationally-molded bubbler having a one-piece body.
Figure 5 is a side, cutaway vi~w of a thermal
level detector.
Figure 6 is a longitudinal cross-section of the
outlet tube with a compression connector and rupturing
tool shown in phanto~
Figure 7 is an exploded perspective view of a
seal-rupturing connector.
Detailed Desc ~
With reference to ~igure 1, the bubbler 10
according to the present invention is an enclosed
rigid-walled container having a wall 12 made of organic
polymer material. On the outside o~ the wall 12 is a thin
metal coating 1~.
The organic polymer material is sel~cted to be
compatible with the liqui~ source materials to be placed
in th~- cos~tainer. A nonreactive polymer ls ~,ssential to
avoid contamination of the liquid source material. One
type of pol~ner sakisfying this requirement for m~ny years
is polyethylene. Ultra high molecular weight or
high-denslty polyethylene ("LHDPE") is particularly
preferred. Other suitable polymers include other
polyolefins, polyvinylidene chloride (PVDC), and
ethylene/vinyl alcohol copolyrner. ~he use of a poly~nide
such as a nylon as a filler in the polym~r may further
increa~e ~esirable properties by creating an additional
tortuous ~pa th barrier.
Organic fluoropolymers and copolymers ~r~ also
suit~ble for making the disposable bubbler. Suc~.
materials include polytetrafluoroethylcne, hexafluoro-
propylene/tetrafluoroethylene copolyrner, ethlene/chl~ro-
trifluoroethylene, ethylene/tetrafluoroethylene copolymer,pol~inylidenefluoride, polyvinylfluoride, and the li!ce.
High mol~cular weight polyethylene tereph~halate
may be suitable, either alone, or in combination with
another polymer such as ethylene/vinyl alcohol copolyn~r
or polyvinylidene chloride.
Still other polymers which may be suitable for
purposes of the present invention lnclude, ei~her alone or
~5 in combination 9 other polyvinyl resins, urea formalde-
hydes, melamine formald~h~des, phenolics, furans,
polyimides, polyxylenes, polyvinylesters, polybenzi-
midazoles, polyphenylenes, polymethylene oxides (acetal),
and chlorinated polyethers.
Multi-lclyer material consisting ol' more than one
orqanic polymer may also advantageously be used. ~or
example, the wall 12 rnay have an inner layer of one of the
polyolefin~, which are relatively nonreactive polyrners,
and a next layer of a material such as polyvinylidene
chloride, which has good v~por barrier propertie~. Oth~r
layers may be added to improve barrier properties, provide
increased strength, or to ta~e advantage of advantageous
properties of other polymers. A preferred layered polymer
material has an inn~r layer of L~DPE, prefera~1e filled
with nylon, a barrier layer of ultrd high molecul~r w~lght
polyethylene polyvinylidene chloride, and an out~r layer
of ultra high molecul~r weight polyethylene LHDPE, a~ain
prefer~bly incorporating nylon ~s a fill~r. An adhesive
or "tie material~ is used to bond the layers, as is
conventional.
Although the foregoing organic polymer mater~ials
possess sufficlent barrier properties for ~ost conven-
ional applications, they may, by themselves, be unsuitablefor purposes of the present invention becduse mi~ute but
harmful anIounts OL moisture and air may, nevertheless,
diffuse through the material ~d into the container.
Accordingly~ to maximize the barrier prop~rties of the
~all 12, the present invention provides a metal coating 1~
on the exterior of the bubbler. Such a metal coating
provides a highly effective barri~r to gas and moisture.
Although the metal is ap~lied to the outside of the
container, it is nevertheless desirable that the metal be
rela~ively nonreactive with the liquid source material
inside the container becduse of possible spilla~e Gf the
liquid on the container exterior, or other inadYertent
contamination. Suitable metals include nickel, chrornium,
zinc, tantalum, tungsten, molybdenum, and zirconium. Of
these, nickel, chromiunI, and ~inc are particularly
preferred. Aluminum and s~ainless s~eel may be considered
in applications where their relatively reactive nature is
not a problem. Any of the noble metals, especially
platinum, would also be suitable, although cost will
usually be a drawback.
The metal coating proca~ is prefer~ly carried
out by sputtering, or by a conventional vapor-deposition
process. To prevent dama~e to the metal coatingV a
scratch-protection coating may be applied after
metallization. A transparent polymer co~tin~, such as
polyvinylidene chloridev polyurethane, or L~DPE is
preferred, although other protective coatings, such as
paint, may be used. This coating i5 preferably applied to
3.~
(
th~ bubbler as ~ melt an emulsiorI a suspen~ion or l~ ~
solvent vehlcle. 1`he use o~ such a coa~in~ may ~lso
render ,nore practic~l th~ ù~e of inexpcJnsive but reactive
rnetal~ ~u~h as alwninum.
rO c-ven further enhance the barrier properties
of the organlc polyIller material, it may be fluorinate~ as
disclose~ ln U.S. P~tents 3 998 180 ~. CUl 57~ a"~
4 1~2 032.
A~ is shown ln F;gure ?, the bubbler 10 may be
formed of a top piece 16 and a bottom piece 1~. Two-piece
construction simplifies in~`ection moldin~ processes and
is also suitable whén the bubbler is forrned of layer~d
sheet stock b~ vacu~n molding If the bubbler is formed
in two pieces 16 arld 18 the pieces may be joined by any
suitable methcd such as by ultrasorIic welding.
Alternatively the I~ubblcr lo rn~y ~e ~ormed in
one piece by rotational molding or blo.J moldin~ a~ is
s.hown in ~igure 4. One piece construction simplifies the
molding proce~ and eliminates tht-~ oircu~ferential seam a
potential trouble spot and sourcè of l~ak~lge in
two-piec~ design.
The bubbler 10 has an inlet tu~e 20 extendin~
~enerally, vertlcally throu~h the top of the bubbler lU
into the interior of the bubbler 10 c~nd extendin~ to
within close proximity of the bottonI of the container. The
irlet tube 20 has an openin~ at the bottom thereof in
order th~t a carrier gas m~y be introduced into the
bubbler through the inlet tube 20, and mcl~ bubble up
through the liquid source material in~ide the ~bbler
~o whereby the carrier ~s becomes saturated with thI: liquid
~ource materialO Altern~tiv~ly, the i~le~ tube rnay extend
throu~h the side or the bottom of the bu~bler lO.
An outlet tube 24 ls ~lso provided to perrr~it the
~aturated carrier gas to flow out of the bubbler 10 to be
utilized in whatever manner is desired. T~Ie outlet tube
24 extends throu~h the top of the bubbler 10 into the
inside a~d h~s an open end inside the bubbler lO near the
top thereof.
.: ~ - :
.. . . .
: '' ~ . . ~ ' - '
,' , , . '
- .: . :
The bubbler 10 may also be provided with a fill
tube 26 extendlng ~hro~gh the top of the bubbler 10 into
t~e interl~r ~hereof for lntroducing liquid source
material lnto the bubbler. A thermowell tube 28 may also
be provided, The thermowell tube 28 extends through the
top of the bubbler 10 and extends generally vertically
down into the inside of the bubbler 10. The therrllowell
tube, unlike the inlet tube 20, the outl~ tube 2~, and
the fill tube 26, has a closed bottom end. One purpose of
the thermowell tube is to permit the temperature of the
liquid source material contained in the bubbler 10 to ~e
monitored, In use, the thermo~ell tube 28 is at least
partially filled with a heat transfer substance, such as
mineral oll or a silicone oil. A temperature sensor in
the thermowell tube can, thus, monitor the temperature of
the liquid source materi~l.
A liquid lev~l det~ctor 30 is provided to permit
remote monitoring of the level of the liquid source
material. Although any ty~ of liquid level detector
desired may be used, the preferred detector is a two-part
detector h~ving a fix-d portion 32, and a movable portion
3~. The nlovable portion 3~ may comprise a magnetic
material encased or coated in a nonreactive subscance su~h
as fluorinated polyethylene. In the embodiment sho~n in
~i~ure 1, the nlovable portion is slidably mou~ted on the
thermowell tube 28. 1'he movable portion 34 floats on the
liquid source ~.aterial. As the level of liquid sourc~
mat~rial drops, the movable portion 34 slides down the
thermowell tube 28 until lt comes into the proximity of
the fixed detector portion 32. Th~ fixed detector portion
32 comprises means to detect the proximity of the movable
portion 3~. Suitable detectors includ~ a magnetically
actuated reed switch or d coil. The ~ix~d detector
portion 32 may be mo~Lnted either on the outside of the
bubbler 10, or preferably, inside the khermowell tube 2B,
in the form of 34a as shown in Figure 4. Th~ magnetic
mate~ial 35 in movable portion 34a may advdntageously be
contained in a seal~d quartz tube, or other container
~ ~7~
having sufficient alr space lnsid~ to float.
In a preferred embodlm~nt, ~s shown in Figur~ ~,
the movable portion 3~ is ~ hollow, plas~ic co~,t~in~r
surroun~ing the thermowell tube 2~. A nlagnet 35 is
positioned inside the hollow of movable portion 34. An
air space may be provided in movable portion 3~ if
necessary to provide buoyancy. The fixed de~ector portion
32a is provided inside the thermowell tube 28.
Alternativ~ly, the movable portion ~ may contain a
ferrous material, and the fixed detector portion 32a may
ir,corporate a magnet.
In an alternativ~ embodiment, shown in Figure 5,
th~ liquid level detector 130 may ~e thermally actuated~
One suitable design is a small heater 132 in close
proximity to, or in contact with, a thermal switch 13~,
mounted on or in the bubbler 10. Rs long as the liquid
level in the b~bbler 10 is above the detector 130, the
heat from the heater 132 is rapidly conducted away from
the thermal switch 134. When the liquid level drops below
th~ detector 130, the heater causes the th~rmal switch to
open (or close). Suitable he~ters include resistive
heat~rs, such as ordinary resistors, to which a constant
voltage may be applied during operation of the bubbler.
5uitable thermal switches include thermal fuses and
bimetal switches. Other temperature detectors, such as
~hermistors, could also be used.
As illustrated in Figures 3 find 5, a frangible
breakseal 36 is provlded at the top of inlet tube 20 ~nd
outlet tube ~4. The frangible breakseal 36 may be made of
a suitable organic pol~ner material, such as the mat~rial
comnrising the walls of the bubDl~r 10, or i~ may be made
of quartz. The breakseal 36 may be placed in inlet 20 and
outlet 24 by any suitable means, such aS weldin~ or
moldin~. With the fran~ible breakseals 36 in place, the
35 upper ends of the tubes 20, 24, 26 and 28 are th~
covered. ~ preferred method of ~overing the ends is with
an adhe~ive tab 38 as shown in Figure 5. The tab 38 may
be mada o~ any desirad material, although nletal sandwiched
~ ~t~
12
with a suitable polymeric material is preferr~d.
In the ~mbodiment o4 khe fabrication process of
the bubbler 10, in which the top piec~ 16 ar.d the bottom
piece 1~ are separately molded, the tubes 20, 24, 26, and
28 may be fastened into the top piece 16, e.g., by
ultrasonic welding. Alternatively, the tubes 20, 24, 26,
and ~8 may be molded into top piece 16. Both the inside
and the outside of top piece 16 and bottom piece 1~ are
then fluorinated. Alternatively and prelerably, the
fluorination process is per*ormed a~ter assem~ly of the
top piece 16 and the bottom piec~ 18.
In another embodiment of the fabrication
process, the bubbler shell 39 is fabricated in one piece
by rotation molding (Se~ Figure 4). Holes are then
15 pu~-ciled for the tubes 20, 24, 26 and 28, which are spin
welded into place. In order to accommodate the liqu1d
level detector 30, the hole for the thermowell tube 28
mu~t be oversize. An appropri~tely enlarged se~ment is
provided near the top of the thermowell tube to mate with
~0 the oversize hole. The bubbler shell 39, with tubes 20,
24, 2~ and 2~ in place, is fluorinated inside and out.
~ he entire bubbler, including the exposed
portions of the tubes and the tabs 38, is th~n coated with
a thin lay~r of metal, This metal layer is generally at
least 0.2 mils thick, and preferably at least 0.6 mils
thick. Althou~h an electrodeposition plating prGc~ss may
be used, the preferred method~ for applying the metal
coating are by either a vapor deposition process, such as
conventional flashin~, or by sputtering. By applying the
metal coating at a slightly elevated temperature t~g.,
1~0 degrees F), metal-to-polymer binding strength is
increàsed and nucleation is minlmized. The fluorination
step facilitates the subsequent bonding of metal to
plastic ~ithout the u~e of an underlying base coat.
However, lf desired, an extremely light coating (.~
one molecule thick) of copper may be applied as a base
coat. Other conventional base coats may also be used. It
should be noted that, because of the tabs 38, the top
7~
13
surface and interior of the tubes 20, 24, 26 and 2~,
together wi~h the frangibl~ brea~seals 36, are protect~d
froln metallizatlon. Thi~ ~voids any possibility that th~
high-purlty liquid source material may beconle contalni~ted
by the metal us~d for coating.
The tab 38 is then removed from the fill tub~
26, and the bubbler is filled through the fill tube 26
with an ultra high-purity liquid source materidl that is
compatible with the or~anic polymer material, such as
phosphorus oxychloride, phosphorus trichloride, phosphorus
~ribromide, boron tribromide, trichloroethylene,
tetram~thoxysildne, silicon tetrabromide, trichlorethane,
arsenic trichloride, or antimony pentachloride. These
liquid source materials have a purity of at l~ast 99.995X
lS and preferably 99~9999%. Typical irnpurity levels are 200
ppb or less. The fill tube is th~n heat s~aled or closed
by any other appropriate method capable of eliminatin~ the
po~sibility of contamination and leaka~e. The resultin~
container is a hermetically-seal~d bubbler that ~ ets DOT
shipping regulations for the contained liquid source
material. The contalner cost to th~ customer has been
r~duced by approximately 80% to 90% from the cost
associated with a quartz bubbler.
To use the bubbler, the tabs 38 are removed from
~5 the inlet tube 20, the outlet tube 24, and the thermowell
tub~ 2a. ~ valve 40 is then attached to the inlet tube 20
and to the outlet tube 2~ as is shown in ~igure 3. The
inlet tube 20 and the outlet tube 24 may be provid~d with
threads for attachment or t~e valve 40. In on~ embodiment
of the invention, the external portions of the inlet tube
~0 and the outlet tube 24 a~e eliminated and the valves
are screw~d directly into threads holed in the top of the
bubbler body. Alternatlvely, th~ valves ~0 may be
attached to the inlet tube 20 and the outlet tube 24 by
means of a compression fitting, or by any other suitable
means.
The valve 40 ~hown in Figure 3 has a valve body
¢4, an inlet end 46 for attac~nent to the outlet tube 24,
and an outlet end ~8, for attachment to a gas l ir.e 50 . In
the interior of the valve, there is a fluid control means
54 for controlling ~he flow of a fluid throush the valve.
In th~ illustrated embodiment, the fluid control rn--ans 54
comprises a movable ma~ing surface 56 Which iS rnoved into
contact with a valve seat 58 to interrupt the flow of
~luid thr~ugh the valve. The mating surface 56 i~
actuated by a valve stem 60. In the illustrated
embodiment, the valve stem 60 has a ~hreaded portion 64 so
that the mating surface 5~ may be moved in~o and out o:f
contact ~ith the valve seat 58 by rotating the valve stem
60.
On the mating surface 56, and extending through
the va~ve seat 58, is a rupturing device 66. A pointed,
solid rupturing device 66 as in Figure 3 is appropridte
for quartz or glass breakseals. Polylner breakseals
usually require a rupturing device 65 capable of
maintaining an open fluid passageway through the
breakseal. A sharpened tube, as shown at 66a in phantom
in Figure 6, is one suitable design. Other suitable
designs may be finned or fluted.
The rupturing device 66 is movable ~y actuating
the valve stem to rupture the frangible breakseal 36.
~ he valve CO is connected to the outl~t tube 2
by any suitable means. In the illustrated e~ odiment, the
inlet end 46 is provided with exterior thr~ads onto which
a compression nut 6~ can he threaded. The nut ~e has an
annul~r axial opening therein in order that i~ may tit
over the outlet tub~ 24. To connect the valv~ 4C ~o the
outlet tube 2~, the nut 68 and a tapered annular f~rrule
70 are placed on the outlet tube 24. The inlet end 46 of
the valve SO is then placed on the outlet tube 24 and the
nut 68 is screwed onto the inlet end 46, ~ompressing the
tapered ferrule 70 against a matching inner taper 72 in
the inlet end 46 and a~ainst the outlet tube 2~o If
desired, a notch 73 may be provided in the inl~t tube 20,
and the outlet tube 24 to acco~nodat~ the ferrule 70 tor
an "O-ring" or other suitable seal) as shown ln ~igure 3.
~ ~7~
A similar nut 68 and ferrule 70 dre provided for
cor~ecting the gas line 50 to the outlet end ~8 of the
~alve 40 in th~ same manner.
A st~rrl seal 74 is provided in the valve body 4~,
and is in contact with the valve ~tem 60. The ferrules 70
and the stem seal 7~ prevent all rnoisture and vdpor frorn
th~ exterior of the valve bo~y 4~ from reaching the
interior of the valve body ~4.
In a preferred embodiment, the entir~ valve body
4~, or at least the interior thereof, is made of a
nor~netallic materihl that is not reactive with, ar.d will
not contaminate the contents of the bubbler~ Suitable
nonreactive materidls include organic pol~,ler materials,
such as are used in the bubbler, inorganic polymers, such
as silicones, ceramic materials, and glass. The ferrule
70 and the stem seal 7~ may also be made of a suitable
nonreactive material, such as nylon, polytetrafluoro-
ethylene, polyethylene, silicone, or any of the polymers
from ~hich the bubbler lO is made. How~ver, the preferred
~0 mat~rial for the ferrule 70 and the stem seal 74 ls
graphite.
Although one particular v~lve design is
illustrated, it will ~e understood that the v~lve of the
present invention may utilize any type of fluid control
~5 means 5~, and may be a ball valve, a ne~dle-and-seat
valv~, a gate valve, a plug valve, a disk v~lve, a
butterfly valve, a telescoping valve, a slide valve, or
any other suitable type of fluid control valve.
Regardless of the particular type of valve, all
~0 of the valves within the scope of the present invention
will have an air- and vapor-ti~ht seal at the inlet, the
outlet, and any other channel leading into the interior of
the valve.
Th~ valve 40 is preferably coated ~ith a layer
of metal 75 of the same type and in the same manner as the
bubbler 10, in order to eliminate the possi~ility of
moisture pel~meation through the valve. The entire
exterior of the valYe 40 is covered with metal up to the
~ ~7~
16
seals that protect the interior of ~he valve ~0 from
contamination, e.g., the ferrules 70 and the s~em seal 74.
When the valve is made of the same organic polymer
material as is used for the bubbler, it is prefer~ed that
the valve is fluorinat~d prior to being co~ted with metal.
The nuts 68 may also advantageously be ~letal coated both
inside and out. However, it is critical that all valve
parts in fluid connection with the interior of the valve
have no metal therein which could contact the fluid
passing through th~ valve.
Thus, the valve according to the present
invention hds a metal exterior, a nonreactive non~metal
interior, and vapor-impermeable seals between the
non-metal interior and the metal exterior of the valve 40.
In use, the valve ~0 is attached to the outlet
tube 24 with a compression fitting as described above, by
threading the valve 40 into the body of the bubbler 10, or
by any other suitable means. The gas line is also
attached to the valve 40, and the valve is purged with an
inert gas. The rupturing device 66 is then actuated to
rupture the fr~ngible breakseal 36, thereby permitting the
flow of gas out of the bubbler.
A second valve ~0 is connected to the inlet tube
20 of the bubbler 10 in the same manner aS described
above.
In some applications, a fluid-control valve on
the inlet tube 20 and the outlet tube 24 is not neces'sary.
For example, users often have fluid control valves in the
~as line 50 itself, or at other points in the system.
Accordingly, there is also provided in accordance with the
present invention a simple "tee" connector 76. The "t~e"
connector 76 has a top end 7~, a bo~tom end ao for
connection to the outlet tube 2~, and an outlet end ~4 for
connection to a gas line 50. As is shown in Figure 7,
~5 annular nuts 68 ~re provided for connecting the outlet
tube 24 and the gas line 50 (not shown) to the "tee"
connector 76,
A plun~er 86 is provided which is inserted most
~ ~7~
17
of the way into the top end 78 of the "tee" connector 76.
The plunger 86 has a sharp~ned lower end ~a for r~pturin9
th~ breakseal ~6. In the illustrated embodilnent, the
plunger 86 is tubular so that when extending through the
breakseal, it can hold the frayments of the ruptured
breakseal op~n an~ provide a qas pas~ageway through the
breakseal. A hole 90 is provided through ~he side of the
plunger 86 and into the hollow interior so th~t gas may
flow up through the plunger ~6 (which has a smaller
outside diameter than the inside of the "tee" ccnnector
76), out through the hole 90, and through the outlet end
84 of the "tee" connector 76 to the gas line 50 to be used
as desired.
Once the bottom end 80 and the outlet end 84 of
the "tee" connector 76 are connected, and the plunger 86
is positioned above the breakseal 36 through the top end
78, a threaded cap 94 is screwed part way onto the threads
at the top end 78. The connector is then purged with an
inert gas, prefer~bly the carrier gas. The ~reakseal 36
~0 is then ruptured by screwing the cap 94 tightly onto the
top end 78 of the "tee" connector 76, bringing the cap ~4
into contact with the plunger 86, and forcing it through
the breakseal 36.
The "tee" connector 76, like the ~alve ~0, may
be made of any suitable material possessing the necessary
barrier properties, and may advantageously be made of the
same polymer mdterial as the bubbler. Similarly, the
plunger 86 may be made of the same material as the valve,
or, alternatively, it may be made of a different polymer,
or of any other nonreactive material, such as quart2.
A second "~ee" connector is attached to the
inlet tube 20 in the same manner as discussed above in
connection with the outlet tube 24.
In an alternative embodiment, the valves 40, or
connectors 76, may be attached to the bubbler before
~hipping, either conventionally, or by molding or w--lding
them onto the tubes, or into the top of the bubbler 10 in
place of the tubes. In this embodiment, the breakseal 36
~ ~7~
18
may eit~er remain in the top of tubes 20 and 2~, as
di~closed above, i~ may be in the bub~ler body itself ~as
when the valve is threaded directly ~nto the bubbl~r), or
it may b~ provided in the valve body of a conventional
valve so that the valve is ~et~en ~he breakseal and the
liquid source material. Mor~over, to the extent
consist~nt with safety and purity, and permissible under
applicable shipping reyulations in the country of
shipm~nt, the breakseal may be eliminated altogether. By
attaching the valve prior to shipment, the valve may be
coated with met~l at the same tim~ as the bubbler, thereby
enhancin~ the barrier properties of the valve, and ~urther
minimizing the chance of contarrlination of the source
material.
The invention is more fully illustrated in the
following E~ample 1.
EXAMPLE 1: 1500 cc Bubbler
Ultra high molecular weight poly~thylene
(UHMWPE) or linear high density polyethyl~ne ~s
rotationally molded into a generally cylindrical
rigid-wdlled container having a 1500 cc capaci~y. Th~
wall thickness is approximately 1/8 inch. Four round
holes are then punched in the top of the container, in
which an inlct tube, an outlet tube, a thermGwell tube,
and a fill tube are inser~ed and positioned. These tubes
are then spin welded to attach them to the container body.
The thermowell tube has a sealed bottom end. An annular
LHDPE or UHMWPE float containing a magnet is slida~ly
positioned on the thermowell tube inside the containèr.
The irlet tube and the thermowell tube extend to within
close proximity of the bottom of the container; the fill
tube and the outlet tube terminate just inside the
container.
Breakseals comprising 0.020 lnch thick disks of
LHDPE or UHMWPE are positioned in the top of the inlet
tube and the outlet tube, and are ultrasonically welded
into place. The container is then pressure tested at 25
psi.
~ ~27~
19
Following pressure ~esting, the bub~ler is
fluorinated. The bubbler is preheated ko 1~0 d~grees F
for one-half hour, th~n pl~c~d in a vacuum chamber.
followin~ evacuation, N2 and F2 gas is introduced at
atmospheric pressure for one hour. The bubbler then
passes to the metallization process.
Metal sandwiched plastic t~bs are attached to
the top ends of the tubes with induction h~ating. A b~se
coat is applied to the bubbler, which is then dried at 140
degrees ~ for one-half hour. The dry bubbler is plac~d in
th~ sputtering chamber, which is evacuated for 20 minutes
to about 0.05 torr. Chromium is sputt~red onto the
exterior surface of the bubbler for two minut~s to depo~it
a 0.6 to 1 mil metal coatingO A clear, protective
polyvinylidene chloride coating is applied to the exterior
of the container over the metal, and the container is
dried for 20 minutes at 140 degrees F.
The fabricated bubbler is next washed, dried,
and filled with liquid trichloroethane, havin~ a purity of
~0 99.9999~. The fill tube is then heat sealed.
A nut is placed on both the inlet tube and the
outlet tube, and a flat plug is placed over the end of
eacll tube ~nd is secured in pl~ce with the nut. The
chemical-filled bubbler is double bag~ed in polyvinylidene
~5 chloride film and is placed inside a form-fitting
styrofoam container. The container is then packed inside
a cardboard oontainer and shipped to the customer.
Although the present invention has b~en
described in term~ of certain preferred embodiments, it
will be understood that some modific~tions n,dy be made by
those of ordinary skill in the art, without departing from
the spirit of this invention. Accordingly, it is intended
that the scope of the pr~sent invention b~ measur~d only
by th~ ~ppended claims, and reasonable equivalents
thereof.
~ndustrial_A~plicdt_on
This invention finds application in the
manufacture of semicon~uctor, electronic ~nd optical
devices.
