U.S. patent application number 10/427711 was filed with the patent office on 2004-02-12 for composition and process for removing moisture from hydrogen halides.
This patent application is currently assigned to Mykrolis Corporation. Invention is credited to King, Mackenzie.
Application Number | 20040026327 10/427711 |
Document ID | / |
Family ID | 25415893 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040026327 |
Kind Code |
A1 |
King, Mackenzie |
February 12, 2004 |
Composition and process for removing moisture from hydrogen
halides
Abstract
A composition comprising a magnesium halide coated macroporous
carbonaceous substrate is provided for effecting moisture removal
from a hydrogen halide fluid. Moisture removal is effected by
intimately contacting the hydrogen halide fluid with the magnesium
halide coated macroporous carbonaceous substrate and separating the
fluid from the coated substrate.
Inventors: |
King, Mackenzie; (Danbury,
CT) |
Correspondence
Address: |
HAMILTON, BROOK, SMITH & REYNOLDS, P.C.
530 VIRGINIA ROAD
P.O. BOX 9133
CONCORD
MA
01742-9133
US
|
Assignee: |
Mykrolis Corporation
Billerica
MA
|
Family ID: |
25415893 |
Appl. No.: |
10/427711 |
Filed: |
May 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10427711 |
May 1, 2003 |
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09653214 |
Aug 31, 2000 |
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09653214 |
Aug 31, 2000 |
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08902459 |
Jul 29, 1997 |
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Current U.S.
Class: |
210/689 |
Current CPC
Class: |
B01J 20/046 20130101;
B01J 20/3071 20130101; B01J 20/3236 20130101; B01J 20/20 20130101;
B01D 2253/308 20130101; C01B 7/0718 20130101; B01D 2253/10
20130101; B01J 20/3078 20130101; B01J 20/3204 20130101; C02F 1/283
20130101; C02F 1/288 20130101; B01J 20/28078 20130101; B01D 53/261
20130101 |
Class at
Publication: |
210/689 |
International
Class: |
B01D 015/04 |
Claims
1. A composition suitable for effecting removal of water from a
hydrogen halide fluid which comprises a macroporous carbonaceous
support coated with a magnesium halide.
2. The composition of claim 1 wherein said magnesium halide is
magnesium chloride.
3. The composition of claim 1 wherein said magnesium halide is
magnesium bromide.
4. Te composition of claim 1 having a water absorption capacity in
excess of about 60 liters of water per liter of said
composition.
5. The composition of claim 2 having a water absorption capacity in
excess of about 60 liters of water per liter of said
composition.
6. The composition of claim 3 having a water absorption capacity in
excess of about 60-liters of water per liter of said
composition.
7. The process for removing moisture from a hydrogen halide fluid
which comprises intimately contacting said fluid with a macroporous
carbonaceous support coated with a magnesium halide and separating
said fluid from said coated support.
8. The process of claim 7 wherein said magnesium halide is
magnesium chloride.
9. The process of claim 7 wherein said magnesium halide is
magnesium bromide.
10. The process of claim 7 wherein said hydrogen halide is a
gas.
11. The process of claim 8 wherein said hydrogen halide is a
gas.
12. The process of claim 9 wherein said hydrogen halide is a
gas.
13. The process of claim 7 wherein said hydrogen halide is a
liquid.
14. The process of claim 8 wherein said hydrogen halide is a
liquid.
15. The process of claim 9 wherein said hydrogen halide is a
liquid.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a composition and process for
removing moisture from a hydrogen halide.
[0003] 2. Description of the Prior Art
[0004] At the present time, gaseous and liquid hydrogen halides are
utilized as high purity anhydrous compositions. Anhydrous hydrogen
halides are commonly used in the semiconductor industry such as for
cleaning reactor tubes and susceptors and as an etchant for
manufacturing microcircuits.
[0005] In such applications, highly efficient water vapor or liquid
removal from hydrogen halides such as hydrogen chloride is required
before its introduction to the end-use environment. Hydrogen
chloride is normally a gas and sometimes is transported, under
pressure, as a liquid. Hydrogen chloride becomes a liquid at 615
psig. Water-containing hydrogen chloride is highly corrosive in
character, and thus will necessitate frequent replacement of
piping, manifolds, valves, etc., with which it comes into contact.
In cleaning susceptors, i.e., the support structures on which
wafers are processed, the presence of water in the hydrogen
chloride will result in the formation of new oxides on the
susceptor, thus opposing the cleaning function which is sought to
be carried out. In etching applications, water-containing hydrogen
chloride is a source of undesirable moisture contamination in the
semiconductor manufacturing environment, which may render the
microcircuitry chip products made in such an environment deficient
or even useless for their intended purpose.
[0006] Among the methods which have been utilized by the prior art
for removing water from hydrogen chloride is the use of
moisture-sorptive molecular sieves. The difficulty of employing
such methods for production of high-purity hydrogen chloride is
that hydrogen chloride is competitive with water for the absorption
sites on the molecular sieves. As a result, it is not possible to
obtain the necessary lower residual water values, on the order of
10 parts per million by volume concentration and less, in the
effluent from the molecular sieve contacting step.
[0007] Hydrogen chloride has also been treated with sulfuric acid
or phosphoric acid to produce dehydrated hydrogen chloride. Such
dehydration methods, however, have the associated disadvantage that
they add sulfur or phosphorous to the hydrogen chloride, and these
added elements are highly undesirable contaminants in the
aforementioned semiconductor manufacturing applications.
[0008] It has also been proposed to utilize magnesium chloride
supported on alumina to effect removal of moisture from a hydrogen
halide. It has been found that this purifying material is
undesirable when contacted with high pressure hydrogen chloride
such as in its liquid form since aluminum reacts with the hydrogen
chloride to form aluminum trichloride particles which clog filters
through which the hydrogen chloride is passed to effect its
purification.
[0009] In addition, the formation of magnesium chloride on alumina
involves multiple reaction steps wherein the alumina is first
coated with a solution, e.g., 15% by weight of dibutylmagnesium in
hexane solvent. The solvent is removed by evaporation while
heating. The dibutylmagnesium is converted to magnesium hydride on
alumina by heating to about 250.degree. C. The magnesium hydride
then is converted to magnesium chloride on alumina with
concentrated hydrogen chloride. This composition then is used to
remove moisture from hydrogen halides.
[0010] Hydrogen bromide is another example of a hydrogen halide
which is required in essentially completely water-free condition in
the semiconductor manufacturing field. Hydrogen bromide is used in
the electronics industry as an etchant for wafers, and as a
cleaning agent for susceptors. In these applications, the presence
of water impurity in the hydrogen bromide will result in the same
disadvantages noted hereinabove in connection with hydrogen
chloride in similar applications. In addition, when hydrogen
bromide is used as an etchant for wafers, hazing has been found to
result when the hydrogen bromide contains even minute amounts of
water vapor.
[0011] The art has attempted to achieve removal of water from
hydrogen bromide by the use of phosphoric acid as a drier. This
method, while generally useful to remove the water contaminant,
nonetheless has the attendant disadvantage that it adds phosphorous
to the hydrogen bromide, which as indicated above in connection
with hydrogen chloride, is a significant contaminant in the
semiconductor manufacturing process.
[0012] Accordingly, it would be desirable to provide a composition
and process for removing moisture from hydrogen halides and which
does not produce a contaminating by-product such as particles. In
addition, it would be desirable to provide such a composition and
process which has a high capacity for removing moisture from
hydrogen halides either in gaseous or liquid form. Furthermore, it
would be desirable to provide such a composition which can be
formed from a simplified process as compared to presently available
processes for forming analogous compositions.
SUMMARY OF THE INVENTION
[0013] This invention provides a composition for removing moisture
from a hydrogen halide fluid comprising a macroporous carbonaceous
support upon which is deposited a magnesium halide which is either
magnesium chloride or magnesium bromide. The magnesium halide is
deposited on the surface of the macroporous carbonaceous support
for first admixing the support with a solution of dibutyl magnesium
in order to coat the surfaces of the support with dibutyl
magnesium. The solvent forming the solution then is removed by
evaporation in a non-reactive environment. Thereafter, the coated
support is contacted with hydrogen halide fluid to convert the
dibutylmagnesium to the magnesium halide. This process avoids the
need for forming magnesium hydride.
[0014] In use, the support coated with magnesium halide is
intimately contacted with a hydrogen halide fluid to effect
substantially complete removal of moisture from the hydrogen halide
fluid. The halide of the hydrogen halide fluid and of the magnesium
halide must be the same to prevent contamination of the fluid.
BRIEF DESCRIPTION OF THE DRAWING
[0015] FIG. 1 illustrates the use of the present invention.
[0016] FIG. 2 is a graph of a Foerier Transform Infra Red spectra
illustrating the water removal capacity from nitrogen of the
composition of this invention.
[0017] FIG. 3 is a graph of a Foerier Transform Infra Red spectra
illustrating the water removal capacity from HCl of the composition
of this invention.
DESCRIPTION OF TE SPECIFIC EMBODIMENTS
[0018] The composition of this invention comprises a macroporous
carbonaceous support having an average pore size greater than about
100 Angstroms up to about 100 .mu.m, preferably between about 20 A
and about 1000 A which is coated with magnesium halide. Suitable
carbonaceous supports are formed, for example, by pyrolyzing
polymeric resins. Representative suitable supports are formed by
pyrolyzing sulfonated styrene/divinylbenzene macroreticular ion
exchange resin and are disclosed, for example, by U.S. Pat. No.
5,094,754, which is incorporated herein by reference. Such
carbonaceous supports are available from Rohm and Haas Company,
Philadelphia, Pa. under the registered trademark
AMBERSORB.RTM..
[0019] The magnesium halide coating is formed on the particulate
macroporous carbonaceous support by first intimately contacting the
support with a solution of adialkyl magnesium compound such as
dimethyl, diethyl, dibutyl or dipropyl magnesium, preferably
dibutyl magnesium. Representative suitable solvents for forming the
solution include hexane, heptane or the like. Contact of the
support and the solution typically is effected for a time between
about 1 hour and about 4 hours, at a temperature between about
25.degree. C. and about 70.degree. C. The resultant coated support
is separated from the solution and excess solvent is removed
therefrom such as by evaporation. Evaporation can be effected by
heating such as to a temperature between about 55.degree. C. and
about 65.degree. C. in an inert or nonreactive atmosphere such as
nitrogen or an inert gas.
[0020] In a final step, the coated support is contacted with a
hydrogen halide gas either alone or in a non reactive carrier gas
such as nitrogen wherein the hydrogen halide comprises between
about 5% and 100% volume percent of the gas. In this final step,
the dialkyl magnesium is converted to magnesium halide Hydrogen
chloride is utilized as the hydrogen halide when the coated support
is used to dry hydrogen chloride fluid. Hydrogen bromide may be
utilized as the hydrogen halide when the coated support is used to
dry hydrogen bromide fluid. Contact with the hydrogen halide fluid
is effected for a time and at temperature wherein substantially
complete conversion of the dialkyl magnesium to the magnesium
halide is effected. Typical contact times are between about 1.1
min/ml of resin and about 5.5 min/ml of resin, preferably between
about 1.6 min/ml and about 5.5 min/ml. Typical reaction
temperatures are between about 25.degree. C. and about 240.degree.
C., preferably between about 40.degree. C. and about 60.degree.
C.
[0021] The compositions of this invention are capable of removing
moisture from a hydrogen halide fluid even at high pressures
wherein the fluid is a liquid without formation of reactive
products such as particulate reaction products which contaminate
the hydrogen halide. In addition, the compositions of this
invention are capable of withstanding high pressure liquid halide
up to a pressure of about 1100 psig at 50.degree. C.
[0022] The magnesium halide coating is sufficient to render the
composition of this invention useful for removing moisture from a
hydrogen halide fluid to less than about 100 ppb, preferably less
than about 50 ppb but without significantly blocking the support
macropores. The compositions of this invention are characterized by
a moisture absorption capacity in excess of about 40 liters of
water per liter of coated support, preferably in excess of about 60
liters of water per liter of coated support. The concentration of
magnesium halide exceeds at least about 0.1 moles of magnesium
halide per liter of carbonaceous support, preferably in excess of
at least about 1.2 moles of magnesium halide per liter of
carbonaceous support.
[0023] In use, the composition of this invention is intimately
contacted with a fluid hydrogen halide either as a flowing fluid
stream or quiescent in a container for the hydrogen halide in a
manner so that substantially all of the hydrogen halide contacts
the composition.
[0024] Referring to FIG. 1, hydrogen halide fluid to be dried is
introduced into inlet 10 of housing 12. The fluid is passed through
a retaining frit 14 and into the bed 18 of the coated carbonaceous
particles of this invention wherein moisture is removed from the
fluid. The fluid then is passed through filter 18 and out outlet 20
to a site of use (not shown).
[0025] The following examples illustrate the present invention and
are not intended to limit the same:
EXAMPLE I
[0026] This example illustrates a method for making the magnesium
chloride coated product of this invention.
[0027] Two hundred (200) ml of Ambersorb.RTM. 563 carbonaceous
adsorbent are cleaned in 200 ml of a 10% methanol/water solution.
Ambersorb.RTM. 563 is available from Rohm and Haas Company,
Philadelphia, Pa. and has a surface area of 550 m.sup.2/g and a
macroporosity of 0.23 ml/g as measured by nitrogen porosimetry. The
solution is poured off and the beads are rinsed three more times
with methanol. The support is air dried until free flowing and then
put into a 1000 ml cylinder with N.sub.2 entering from the bottom
while the cylinder is heated to 100.degree. C. for about 4 hours
until most of the bulk water/methanol solution has been removed at
which point the cylinder temperature is raised to 240.degree. C.
for 15 hours. At the end of this activation period the support is
cooled to 60.degree. C. Enough 15% dibutyl magnesium in heptane
solution is added to fill the void volume of the carbon and then
nitrogen flowing from the bottom of the cylinder is used to blow
off .apprxeq.75% of the heptane. This step is repeated until all
the dibutyl magnesium in heptane has been added. Stirring is
required to achieve a homogeneous mixture and prevent caking. The
dibutyl magnesium on the Ambersorb.RTM. 563 carbonaceous adsorbent
is kept under a 1 slpm nitrogen stream at 55.degree. C. for a full
day and subsequently the carbonaceous adsorbent is isolated,
brought into a glove box and put in a sample cylinder appropriate
for hazardous gas handling. The gas sample cylinder with the
carbonaceous adsorbent is connected to a gas manifold capable of
flowing both anhydrous HCl and dry nitrogen. A two fold excess of
5% HCl in nitrogen and 15 psia and 1000 sccm is passed over the
carbonaceous adsorbent at which point pure HCl at 15 psia and 1000
sccm is then passed over the carbonaceous adsorbent for 30 minutes
and the vessel is then pressurized to 60 psig with HCl overnight.
The carbonaceous adsorbent is purged with 1000 sccm N.sub.2 the
following morning and the sample cylinder is heated to 240.degree.
C. for 52 hours. This purging would be more effective with high
pressure CO.sub.2. The final product emits less than 1 ppm total
hydrocarbons at 26.degree. C.
EXAMPLE II
[0028] This example illustrates the use of the product of this
invention for removal of moisture from nitrogen and HCl.
[0029] Tests were performed to determine whether the coated
carbonaceous adsorbent can dessicate a nitrogen gas stream. To test
water retention, N.sub.2 or HCl gas at 500 sccm is dried with a
conventional hydrogen halide purifier. The HCl gas then is either
passed through the purifier apparatus illustrated in FIG. 1 or can
bypass the purifier. The bypass stream is representative of the
background water level. The resultant gas stream is directed to a
10 meter path length gas cell kept at 130.degree. C. for use with a
Fourier Transform Infrared analysis apparatus (FT-IR). Four (45)
PPM water in 100 sccm N.sub.2 is added to the gas stream (for a
total flow of 600 sccm) on demand.
[0030] The composition of the FT-IR spectrum exhibits the ability
to remove water moisture from N.sub.2 to levels less than 100 ppb.
FIG. 2 shows three FT-IR spectra at 1772 cm.sup.-1 to illustrate
the water retention ability of the composition of this invention in
N.sub.2.
[0031] N.sub.2 dried by the conventional purifier and which
bypasses the composition of this invention is denoted "Dry
N.sub.2". "Water" refers to the wet (4 PPM) N.sub.2 gas stream
which bypasses the composition of this invention and "New
purifier+Water" refers to the wet N.sub.2 passed through the
composition of Example 1. It is evident from the spectra that there
is no difference between "Dried N.sub.2" and "New purifier+Water"
indicating that the conventional purifier and the purifier of this
invention are capable of retaining water to the same level in
N.sub.2 (<100 ppb).
[0032] Referring to FIG. 3, the composition of Example I exhibits
the ability to remove water moisture from HCl to levels less than
100 ppb. FIG. 3 shows three FT-IR spectra at 1772 cm.sup.-1 to
illustrate the water retention ability of the composition of
Example I in HCl.
[0033] HCl dried by the conventional purifier and which bypasses
the composition of Example I is denoted "Dry HCl". "Water" refers
to the wet (4 ppm) HCl gas stream which bypasses the composition of
Example I and "New purifier+Water" refers to the wet HCl passed
through the composition of Example I. It is evident from the
spectra that there is no difference between "Dried N.sub.2" and
"New purifier+Water" indicating that the conventional purifier and
the composition of Example I are capable of retaining water to the
same level in HCl (<100 ppb).
* * * * *