U.S. patent application number 16/685266 was filed with the patent office on 2020-05-28 for low halide lanthanum precursors for vapor deposition.
This patent application is currently assigned to Versum Materials US, LLC. The applicant listed for this patent is Versum Materials US, LLC. Invention is credited to Sergei V. Ivanov, Neil Osterwalder.
Application Number | 20200165270 16/685266 |
Document ID | / |
Family ID | 68731737 |
Filed Date | 2020-05-28 |
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United States Patent
Application |
20200165270 |
Kind Code |
A1 |
Osterwalder; Neil ; et
al. |
May 28, 2020 |
Low Halide Lanthanum Precursors For Vapor Deposition
Abstract
Lanthanide compounds for vapor deposition having .ltoreq.50.0
ppm, .ltoreq.30.0 ppm, or .ltoreq.10.0 ppm of all halide impurity
combined is provided. The purification systems and methods are also
provided.
Inventors: |
Osterwalder; Neil;
(Carlsbad, CA) ; Ivanov; Sergei V.;
(Schnecksville, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Versum Materials US, LLC |
Tempe |
AZ |
US |
|
|
Assignee: |
Versum Materials US, LLC
Tempe
AZ
|
Family ID: |
68731737 |
Appl. No.: |
16/685266 |
Filed: |
November 15, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62772450 |
Nov 28, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C 257/12 20130101;
C07B 63/00 20130101; C23C 16/45553 20130101; B01D 7/00 20130101;
C07F 5/00 20130101; C07C 257/10 20130101; H01L 21/02192
20130101 |
International
Class: |
C07F 5/00 20060101
C07F005/00 |
Claims
1. A composition comprising lanthanide amidinate compound
Ln(AMD).sub.3 having Formula I ##STR00005## wherein R.sup.1 is
selected from the group consisting of hydrogen, and C.sub.1 to
C.sub.5 linear or branched alkyl; and R.sup.2 and R.sup.2 each is
independently selected from the group consisting of C.sub.1 to
C.sub.5 linear or branched alkyl; Ln is a lanthanide selected from
the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho,
Er, Tm, Yb, Lu; wherein the composition comprises at least one
halide impurity and each of halide impurity ranges from 10.0 ppm or
less; and all halide impurities combined ranges 50.0 ppm or
less.
2. The composition of claim 1, wherein the at least one halide
impurity is selected from the group consisting of chloride,
bromide, iodide, fluoride and combinations thereof; and each of
halide impurity ranges from 5.0 ppm or less.
3. The composition of claim 1, wherein the composition comprising
.ltoreq.1.0 ppm chloride, .ltoreq.1.0 ppm bromide, .ltoreq.1.0 ppm
iodide, and .ltoreq.1.0 ppm fluoride.
4. The composition of claim 1, wherein R.sup.1 is hydrogen and the
lanthanide amidinate compound is selected from the group consisting
of La(FAMD).sub.3, Ce(FAMD).sub.3, Pr(FAMD).sub.3, Nd(FAMD).sub.3,
Pm(FAMD).sub.3, Sm(FAMD).sub.3, Eu(FAMD).sub.3, Gd(FAMD).sub.3,
Tb(FAMD).sub.3, Dy(FAMD).sub.3, Ho(FAMD).sub.3, Er(FAMD).sub.3,
Tm(FAMD).sub.3, Yb(FAMD).sub.3, and Lu(FAMD).sub.3.
5. The composition of claim 1, wherein the lanthanide is lanthanum
and R.sup.1 is hydrogen.
6. A system for purifying a crude lanthanide amidinate material for
vapor deposition comprising f) the crude lanthanide amidinate
material comprises lanthanide amidinate compound having Formula I
##STR00006## wherein R.sup.1 is selected from the group consisting
of hydrogen, and C.sub.1 to C.sub.5 linear or branched alkyl; and
R.sup.2 and R.sup.2 each is independently selected from the group
consisting of C.sub.1 to C.sub.5 linear or branched alkyl; Ln is a
lanthanide selected from the group consisting of La, Ce, Pr, Nd,
Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; g) zone 1 comprising at
least one sublimer; wherein the crude lanthanide amidinate material
is placed inside the at least one sublimer; h) zone 2 comprising at
least one condenser; wherein the zone 2 is in fluid communication
with the zone 1; i) zone 3 comprising at least one cooler; wherein
the zone 3 is in fluid communication with the zone 2; and
optionally j) a separation unit selected from the group consisting
of convoluted pathway, glass wool, filter, and combinations
thereof; wherein the separation unit is installed between the zone
1 and the zone 2; wherein the crude lanthanide amidinate material
comprises 50 ppm or more at least one impurity selected from the
group consisting of (i) halide impurities selected from the group
consisting of LnCl.sub.x(AMD).sub.y (x+y=3), LnBr.sub.x(AMD).sub.y
(x+y=3), LnI.sub.x(AMD).sub.y(x+y=3), LnF.sub.x(AMD).sub.y (x+y=3),
wherein x or y is selected from 1 or 2, and combinations thereof;
(ii) light impurities LnO(AMD).sub.2, (iii) trace metals, and (iv)
trace amounts of non-volatile impurities Ln.sub.2O.sub.3,
Ln(OH).sub.3, or combinations; and purified lanthanide amidinate
material is inside the at least one condenser in the zone 2; and
the purified lanthanide amidinate material comprises each of halide
impurity ranging from 10.0 ppm or less and all halide impurities
combined ranging from 50.0 ppm or less.
7. The system of claim 6, wherein the purified lanthanide amidinate
material comprises each of halide impurity ranging from 5.0 ppm or
less.
8. The system of claim 6, wherein the lanthanide amidinate compound
is selected from the group consisting of La(FAMD).sub.3,
Ce(FAMD).sub.3, Pr(FAMD).sub.3, Nd(FAMD).sub.3, Pm(FAMD).sub.3,
Sm(FAMD).sub.3, Eu(FAMD).sub.3, Gd(FAMD).sub.3, Tb(FAMD).sub.3,
Dy(FAMD).sub.3, Ho(FAMD).sub.3, Er(FAMD).sub.3, Tm(FAMD).sub.3,
Yb(FAMD).sub.3, and Lu(FAMD).sub.3.
9. The system of claim 6, wherein the lanthanide is lanthanum and
R.sup.1 is hydrogen.
10. The system of claim 6, wherein the system comprises the
separation unit and the purified lanthanide amidinate material
comprises each of halide impurity ranging from 2.0 ppm or less.
11. The system of claim 6, wherein the system comprises the
separation unit and the purified lanthanide amidinate material
comprises each of halide impurity ranging from 1.0 ppm or less.
12. A method for purifying a crude lanthanide amidinate material
for vapor deposition comprising a. providing the crude lanthanide
amidinate material comprises lanthanide compound having Formula I
##STR00007## wherein R.sup.1 is selected from the group consisting
of hydrogen, and C.sub.1 to C.sub.5 linear or branched alkyl; and
R.sup.2 and R.sup.2 each is independently selected from the group
consisting of C.sub.1 to C.sub.5 linear or branched alkyl; Ln is a
lanthanide selected from the group consisting of La, Ce, Pr, Nd,
Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; and the crude
lanthanide amidinate material comprises at least one impurity
selected from the group consisting of (i) halide impurities
selected from the group consisting of LnCl.sub.x(AMD).sub.y
(x+y=3), LnBr.sub.x(AMD).sub.y (x+y=3), LnI.sub.x(AMD).sub.y
(x+y=3), LnF.sub.x(AMD).sub.y (x+y=3), wherein x or y is selected
from 1 or 2, and combinations thereof; (ii) light impurity
LnO(AMD).sub.2, and (iii) trace amounts of non-volatile impurities
Ln.sub.2O.sub.3, Ln(OH).sub.3, or combinations; b. providing zone 1
comprising at least one sublimer, zone 2 comprising at least one
condenser; and zone 3 comprising at least one cooler; optionally a
separation unit installed between the zone 1 and the zone 2 and the
separation unit is selected from the group consisting of convoluted
pathway, glass wool, filter, and combinations thereof; wherein the
zone 2 is in fluid communication with the zone 1 and the zone 3 is
in fluid communication with the zone 2; c. heating the crude
lanthanide amidinate material contained in the at least one
sublimer in the zone 1 to get crude lanthanide amidinate material
vapor separated from the halide impurities and the trace amounts of
non-volatile impurities; d. passing the crude lanthanide amidinate
material vapor from the zone 1 to the at least one condenser in the
zone 2 and condensing the crude lanthanide amidinate material vapor
to form purified lanthanide amidinate material in the at least one
condenser; e. passing the non-condensed light impurity
LnO(AMD).sub.2 from the zone 2 into the at least one cooler in the
zone 3 to form solid light impurity; wherein the purified
lanthanide amidinate material comprises each of halide impurity
ranging from 10.0 ppm or less and all halide impurities combined
ranging from 50.0 ppm or less.
13. The method of claim 12, wherein temperatures are set between
60.degree. C. to 200.degree. C. in zone 1; between 100.degree. C.
to 180.degree. C. in zone 1; and below 30.degree. C. in zone 3.
14. The method of claim 12, wherein the lanthanide amidinate
compound is selected from the group consisting of La(FAMD).sub.3,
Ce(FAMD).sub.3, Pr(FAMD).sub.3, Nd(FAMD).sub.3, Pm(FAMD).sub.3,
Sm(FAMD).sub.3, Eu(FAMD).sub.3, Gd(FAMD).sub.3, Tb(FAMD).sub.3,
Dy(FAMD).sub.3, Ho(FAMD).sub.3, Er(FAMD).sub.3, Tm(FAMD).sub.3,
Yb(FAMD).sub.3, and Lu(FAMD).sub.3.
15. The method of claim 12, wherein the lanthanide is lanthanum and
R.sup.1 is hydrogen.
16. The method of claim 12, wherein the purified lanthanide
amidinate material comprises each of halide impurity ranging from
5.0 ppm or less.
17. The method of claim 12, wherein the separation unit is used and
the purified lanthanide amidinate material comprises each of halide
impurity ranging from 2.0 ppm or less.
18. The method of claim 12, wherein the separation unit is used and
the purified lanthanide amidinate material comprises each of halide
impurity ranging from 1.0 ppm or less.
19. A vessel containing a composition comprising lanthanide
amidinate compound Ln(AMD).sub.3 having Formula I ##STR00008##
wherein R.sup.1 is selected from the group consisting of hydrogen,
and C.sub.1 to C.sub.5 linear or branched alkyl; and R.sup.2 and
R.sup.2 each is independently selected from the group consisting of
C.sub.1 to C.sub.5 linear or branched alkyl; Ln is a lanthanide
metal selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; wherein the composition
comprises at least one halide impurity and each of halide impurity
ranges from 10.0 ppm or less; and all halide impurities combined
ranges 50.0 ppm or less.
20. The vessel of claim 19, wherein the at least one halide
impurity is selected from the group consisting of chloride,
bromide, iodide, fluoride and combinations thereof; and each of
halide impurity ranges from 5.0 ppm or less.
21. The vessel of claim 19, wherein the lanthanide amidinate
compound is selected from the group consisting of La(FAMD).sub.3,
Ce(FAMD).sub.3, Pr(FAMD).sub.3, Nd(FAMD).sub.3, Pm(FAMD).sub.3,
Sm(FAMD).sub.3, Eu(FAMD).sub.3, Gd(FAMD).sub.3, Tb(FAMD).sub.3,
Dy(FAMD).sub.3, Ho(FAMD).sub.3, Er(FAMD).sub.3, Tm(FAMD).sub.3,
Yb(FAMD).sub.3, and Lu(FAMD).sub.3.
22. The vessel of claim 19, wherein the lanthanide is lanthanum and
R.sup.1 is hydrogen.
23. The vessel of claim 19, wherein the composition comprising
.ltoreq.1.0 ppm chloride, .ltoreq.1.0 ppm bromide, .ltoreq.1.0 ppm
iodide, and .ltoreq.1.0 ppm fluoride.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a non-provisional of U.S.
provisional patent application Ser. No. 62/772,450, filed on Nov.
28, 2018, which is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] The invention relates generally to a composition comprising
lanthanide such as lanthanum precursors containing 10.0 ppm or less
and preferably <5.0 ppm of halide impurities such as fluorine,
chlorine, bromine or iodine. The invention also relates to the
method for deposition of lanthanum-containing films, such as
lanthanum oxide, metal oxide doped with lanthanum oxide, lanthanum
nitride and metal nitride doped with lanthanum nitride.
Lanthanum-containing films are used in electronic industrial
applications.
[0003] Thin films of rare earth oxides are of interest because of
their potential use as dielectrics in microelectronics
applications. In particular, lanthanum oxide (La.sub.2O.sub.3) is
attractive for a number of reasons including its favorable
conduction band offset at the La.sub.2O.sub.3/Si interface. This
and other properties have led some to consider La.sub.2O.sub.3 or
La-containing oxides for use as high-k materials in
metal-oxide-semiconductor field effect transistors (MOSFETs) and
capacitive devices. La.sub.2O.sub.3 has found use as a "capping
layer" to adjust work functions in advanced MOSFETs.
[0004] Lanthanide complexes, such as lanthanum cyclopentadienyl and
lanthanum amidinate complexes are widely used in electronic
industry as precursors for chemical vapor deposition or atomic
layer deposition of lanthanum-containing films. For various
applications, semiconductor industry requires high purity
precursors with trace metals and halide impurities well below
single ppm's for metals and lower than 10.0 ppm for halides. This
is because increasing the speed and complexity of semiconductor
integrated circuits requires advanced processes that put extreme
constraints on the level of contamination allowed on the surfaces
of silicon wafers.
[0005] Metallic and halide contaminations on wafer surface are
known to be a serious limiting factor to yield and reliability of
CMOS based integrated circuits. Such contamination degrades the
performance of the ultrathin SiO2 gate dielectrics that form the
heart of the individual transistors. Halides impurities may migrate
in the device and cause corrosion. The commonly reported mechanism
for electrical field breakdown failure from iron contamination is
the formation of iron precipitates at the Si--SiO2 interface, which
frequently penetrate the silicon dioxide. Halide impurities present
in lanthanum precursors may also cause corrosion of stainless steel
containers used for delivery of lanthanum containing precursors to
the deposition tool and transfer of iron and other stainless steel
metal impurities to the lanthanum-containing film causing device
failure.
[0006] Thus, precursors with low levels of halide contamination are
highly desired. Purification methods to produce precursors with low
halide contamination are also desired.
[0007] Commonly used precursors for deposition of
lanthanum-containing films are lanthanum amidinates or
La(AMD).sub.3, such as for example tris
(N,N'-di-isopropylformamidinato) lanthanum (III) or La(FAMD).sub.3,
lanthanum cyclopentadienyl complexes, such as for example
tris(isopropylcyclopentadienyl) lanthanum (III) or La(iPrCp)3, and
lanthanum diketonate complexes. Most common preparation of such
lanthanum includes lanthanum halides as starting materials
resulting in halide contamination.
[0008] Several methods were previously considered for purification
of lanthanum compounds, for example crystallization and
sublimation.
[0009] Hecker (U.S. Pat. No. 2,743,169 A) taught a sublimation
method that can be used for metal chlorides separation and
purification. Typically, sublimation is operated at reduced
pressure, which can enhance the productivity and reduced operation
temperature. The product is usually formed on a cold wall, and is
harvested at the end of the purification process in an inert
environment, as most metal halides are air and moisture
sensitive.
[0010] For better solid product uniformity, fluidized bed is often
used. Another advantage of using fluidized bed is to allow for
automation of solid handling, which is difficult to implement with
vacuum sublimation process. Schoener et al (U.S. Pat. No.
4,478,600) taught a method of using fluidization as part of
aluminum chloride purification process yielding controlled product
particle size. In the art, raw aluminum chloride was firstly
generated through chlorination reaction at high temperature, in
vapor phase, followed by a condensing stage to remove most solid
impurities. The vapor is then supplied into a fluidization chamber
to form product particles. Non-condensable contents, such as
chlorine, carbon dioxide, and fluidizing gas are passed through a
cooling fin for temperature control. Part of the gas is recycled by
a pump, whereas the rest is vented through a scrubber. In this
work, cold fluidization zone is provided for product condensation
and particle formation.
[0011] Thus, the objective of this invention is to provide
lanthanide cyclopentadienyl or lanthanide amidinate complex
containing less than 10.0 ppm of chloride, bromide and fluoride,
preferably less than 5.0 ppm halide, and more preferably less than
1.0 ppm halide.
[0012] Another objective of this invention is to provide lanthanide
formamidinate or La(FAMD).sub.3 containing 50.0 ppm or less, 30.0
ppm or less, 20.0 ppm or less, 10.0 ppm or less, 5.0 ppm or less,
or 2.0 ppm or less of all halide compounds combined.
[0013] Another objective of this invention is to provide a
practical and scalable method for production of low halide
lanthanide formamidinate.
BRIEF SUMMARY OF THE INVENTION
[0014] Accordingly, the present invention provides a low halide
composition; a method and a system to purify a crude material
comprising lanthanide amidinates, or more specifically lanthanum
amidinate compounds to obtain the high purity composition
comprising lanthanum amidinate compounds, and a delivery system to
deliver the high purity composition comprising lanthanide amidinate
compounds.
[0015] In one aspect, there is provided a lanthanide amidinate
compound Ln(AMD).sub.3 having Formula I
##STR00001## [0016] wherein R.sup.1 is selected from the group
consisting of hydrogen, and C.sub.1 to C.sub.5 linear or branched
alkyl; R.sup.2 and R.sup.2 are independently selected from the
group [0017] consisting C.sub.1 to C.sub.5 linear or branched
alkyl; Ln is a lanthanide selected from the group consisting of La,
Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; the
lanthanide amidinate compound comprises at least one halide
impurity selected from the group consisting of chloride, bromide,
fluoride, iodide and combinations thereof; wherein each of halide
impurity ranges from 10.0 ppm or less, 5.0 ppm or less, 2.5 ppm or
less, or 1.0 ppm or less; and all halide impurity combined ranges
50.0 ppm or less, 30.0 ppm or less, 20.0 ppm or less, 10.0 ppm or
less, 5.0 ppm or less, or 2.0 ppm or less by weight.
[0018] The halide impurity comprises fluoride, chloride, iodide
and/or bromide. The halide impurity forms volatile compounds that
are deposited onto the film and have a negative effect on the
dielectric constant.
[0019] In another aspect, there is provided practical and scalable
method for production of high purity Lanthanide amidinate
compounds; comprising [0020] a. providing the crude lanthanide
amidinate material comprises lanthanide compound having Formula
I
[0020] ##STR00002## [0021] wherein R.sup.1 is selected from the
group consisting of hydrogen, and C.sub.1 to C.sub.5 linear or
branched alkyl; R.sup.2 and R.sup.2 each is independently selected
from the group consisting of C.sub.1 to C.sub.5 linear or branched
alkyl; and Ln is a lanthanide selected from the group consisting of
La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; and
[0022] the crude lanthanide amidinate material comprises at least
one impurity selected from the group consisting of (i) halide
impurities selected from the group consisting of
LnCl.sub.x(AMD).sub.y (x+y=3), LnBr.sub.x(AMD).sub.y (x+y=3),
LnF.sub.x(AMD).sub.y (x+y=3), LnI.sub.x(AMD).sub.y (x+y=3), wherein
x or y is selected from 1 or 2, and combinations thereof; (ii)
light impurity LnO(AMD).sub.2, and (iii) trace metals, and (iv)
trace amounts of non-volatile impurities Ln.sub.2O.sub.3,
Ln(OH).sub.3, or combinations; [0023] b. providing zone 1
comprising at least one sublimer, zone 2 comprising at least one
condenser; and zone 3 comprising at least one cooler; optionally a
separation unit installed between zone 1 and zone 2 and selected
from the group consisting of convoluted pathway, glass wool,
filter, and combinations thereof; wherein zone 2 is in fluid
communication with zone 1 and zone 3 is in fluid communication with
zone 2; [0024] c. heating the crude lanthanum amidinate material
contained in the at least one sublimer in zone 1 to get crude
lanthanum amidinate material vapor separated from the halide
impurities and the trace amounts of non-volatile impurities; [0025]
d. passing the crude lanthanide amidinate material vapor from the
zone 1 to the at least one condenser in zone 2 and condensing the
crude lanthanide amidinate material vapor to form purified
lanthanide amidinate material in the at least one condenser; [0026]
e. passing the non-condensed light impurity LnO(AMD).sub.2 from the
zone 2 into the at least one cooler in zone 3 to form solid light
impurity; [0027] wherein the purified lanthanide amidinate material
comprises each of halide impurity ranging from 10.0 ppm or less and
all halide impurities combined ranging from 50.0 ppm or less.
[0028] In yet another aspect, there is provided a system for
purifying a crude lanthanide amidinate material for vapor
deposition comprising [0029] a) the crude lanthanide amidinate
material comprises lanthanide amidinate compound having Formula
I
[0029] ##STR00003## [0030] wherein R.sup.1 is selected from the
group consisting of hydrogen, and C.sub.1 to C.sub.5 linear or
branched alkyl; R.sup.2 and R.sup.2 each is independently selected
from the group consisting of C.sub.1 to C.sub.5 linear or branched
alkyl; and Ln is a lanthanide selected from the group consisting of
La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; [0031]
b) zone 1 comprising at least one sublimer; wherein the crude
lanthanide amidinate material is placed inside the at least one
sublimer [0032] c) zone 2 comprising at least one condenser;
wherein zone 2 is in fluid communication with zone 1; and [0033] d)
zone 3 comprising at least one cooler; wherein zone 3 is in fluid
communication with zone 2; and optionally [0034] e) a separation
unit selected from the group consisting of convoluted pathway,
glass wool, filter, and combinations thereof installed between zone
1 and zone 2; [0035] wherein [0036] the crude lanthanide amidinate
material comprises 50 ppm or more at least one impurity selected
from the group consisting of (i) halide impurities selected from
the group consisting of LnCl.sub.x(AMD).sub.y (x+y=3),
LnBr.sub.x(AMD).sub.y (x+y=3), LnF.sub.x(AMD).sub.y(x+y=3),
LnI.sub.x(AMD).sub.y (x+y=3), wherein x or y is selected from 1 or
2, and combinations thereof; (ii) light impurities LnO(AMD).sub.2,
(iii) trace metals, and (iv) trace amounts of non-volatile
impurities Ln.sub.2O.sub.3, Ln(OH).sub.3, or combinations; [0037]
and [0038] purified lanthanide amidinate material is inside the at
least one condenser in zone 2; and the purified lanthanide
amidinate material comprises each of halide impurity ranging from
10.0 ppm or less and all halide impurities combined ranging from
50.0 ppm or less.
[0039] In yet another aspect, there is provided a delivery system
or a vessel containing the purified lanthanide amidinate compound
as disclosed above as a precursor.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0040] FIG. 1 is an exemplary purification system to remove
halides.
[0041] FIG. 2 is an exemplary purification system having a physical
barrier (such as a filter) between raw material and purified
material according to certain embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0042] The method and the system described in present invention are
generally to remove impurities from Lanthanide amidinate compounds
through phase changing process.
[0043] The purified lanthanide amidinate compound Ln(AMD).sub.3
having Formula I
##STR00004## [0044] wherein R.sup.1 is selected from the group
consisting of hydrogen, and C.sub.1 to C.sub.5 linear or branched
alkyl; R.sup.2 and R.sup.2 are independently selected from the
group consisting C.sub.1 to C.sub.5 linear or branched alkyl; Ln is
a lanthanide selected from the group consisting of La, Ce, Pr, Nd,
Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; the lanthanide
amidinate compound comprises at least one halide impurity selected
from the group consisting of chloride, bromide, iodide, fluoride
and combinations thereof; wherein each of halide impurity ranges
from 10.0 ppm or less, 5.0 ppm or less, 2.5 ppm or less, or 1.0 ppm
or less; and all halide impurity combined ranges 50.0 ppm or less,
30.0 ppm or less, 20.0 ppm or less, 10.0 ppm or less, 5.0 ppm or
less, or 2.0 ppm or less by weight.
[0045] The raw or crude lanthanide such as lanthanum material
mainly comprises up to 99.8 wt. % of primarily target lanthanide
amidinate, and 1 ppm or more, 2 ppm or more, 5 ppm or more, 10 ppm
or more, 50 ppm or more, impurities including but are not limited
to (i) less volatile impurities such as LaCl.sub.x(AMD).sub.y
(x+y=3), LaBr.sub.x(AMD).sub.y (x+y=3); LaI.sub.x(AMD).sub.y
(x+y=3); LaF.sub.x(AMD).sub.y (x+y=3), wherein x and y is selected
from 1 or 2; (ii) light impurities such as LaO(AMD).sub.2, (iii)
trace metals, and (iv) trace amounts of non-volatile impurities
e.g. La.sub.2O.sub.3, La(OH).sub.3, or combinations,
[0046] In general, raw or crude material is heated to certain
temperature, under which lanthanide compounds are vaporized into
gaseous phase in a vaporization chamber. The lanthanide compound
vapor is then condensed into collecting chambers, with one of the
chamber being the main fraction collector where the pure lanthanide
amidinate compounds is collected and harvested. Non-volatile
impurities are left in the vaporization chamber as heel, whereas
the low boiling point light impurities are collected into a chamber
for light impurities collection.
[0047] One aspect of preparing pure lanthanide amidinate compounds
is to remove less volatile lanthanide bromides, chlorides, iodides
and fluorides from raw material. The final purified product
contains 50.0 ppm or less, 30.0 ppm or less, 20.0 ppm or less, 10.0
ppm or less, 5.0 ppm or less, 2.0 ppm or less, or 1.00 ppm or less
impurities.
[0048] According to the Thiele-McCabe method, separation of binary
system at ppm level requires many theoretically plates, which is
not available in vacuum sublimation or fluidized bed system.
[0049] Another aspect of preparing pure lanthanide amidinate
compounds is to remove impurities with lower boiling point
comparing to lanthanide formamidinate. These impurities can be
separated through sublimation by utilizing different boiling points
of product and impurities, through providing at least two
temperature zones. Similarly, such separation can be achieved by
utilizing different vapor pressures at a fixed temperature, and
carrying low boiling impurities away with inert gas. By providing
the suitable amount of inert gas, the Ln impurity can be kept in
gaseous phase while most Ln(FAMD).sub.3 can be condensed, and,
hence achieving separation.
[0050] Yet another aspect of this invention is to prevent product
contamination with trace amounts of non-volatile impurities
accumulated in sublimation heels. Filter media is used to filter
vapor of amidinate compound from trace amounts of less volatile
solid particulates which can be carried over into lanthanum from
amidinate vapor by dusting or other mechanism. Other metal and
halide impurities may also be carried over by the same
mechanism.
[0051] In most embodiments, a purification system comprises of
three series connected chambers: a sublimer where the raw material
is vaporized, a condenser where the product is collected, and a
cooler where the light impurity is collected.
[0052] Crude or raw lanthanide amidinate compound, which typically
has 70-99.5 wt. % of lanthanide amidinate compound balanced with
other impurities, is loaded in the sublimer, and heated to vaporize
lanthanide amidinate compound. The vapor is passed through a heat
traced connecting pipe into the condenser. lanthanide amidinate
vapor is cooled down in condenser to form product. The light
impurity, in vapor phase, is further passed through a heat traced
connecting pipe to enter the cooler, and is cooled down and
condensed in the cooler.
[0053] In certain embodiments, the vapor is forced to pass through
chambers by applying vacuum. In certain embodiments, the vapor is
forced to pass through chambers by inert gas flow. Yet in certain
embodiments, both vacuum and inert gas flow can be applied
simultaneously to force the vapor flow.
[0054] In certain embodiments, the product and light impurities are
condensed by cold surfaces. In other embodiments, the product and
light impurities are condensed by cold inert gas. When condensed by
cold inert gas, the condenser can be made into a fluidized bed so
the product condensed in the gas stream can be nucleation seed and
grow. By controlling the residence time in fluidized bed, uniformed
product particle size and uniformed solid product purity can be
achieved.
[0055] In all embodiment, a separation unit or particle trapper
including but is not limited to convoluted pathway, glass wool,
filter (such as a mediated filter), and combinations thereof; can
be installed in the passage entering the condenser.
[0056] In certain embodiments, the chambers of the purification
system are maintained at fixed temperature. In other embodiments,
some chambers may vary temperature during purification process, to
allow for better separation of light impurities.
[0057] Any of the above features can be combined with any of one or
more other features. Other advantages, novel features, and uses of
the present disclosure will become more apparent from the following
detailed description of non-limiting embodiments when considered in
conjunction with the accompanying drawings, which are schematic and
which are not intended to be drawn to scale or to exact shape. In
the figures, each identical, or substantially similar component
that is illustrated in various figures is typically represented by
a single numeral or notation. For purposes of clarity, not every
component is labeled in every figure, nor is every component of
each embodiment shown where illustration is not necessary to allow
those of ordinary skill in the art to understand the invention.
[0058] An example of the present invention is shown in FIG. 1.
[0059] In some embodiments, the purification system 100 shown in
FIG. 1 comprises at least one sublimer (101), at least one
condenser (104), and at least one cooler (105).
[0060] The sublimer (101) is filled with raw amidinate compound
material (201A). The sublimer is heated to a predetermined
temperature, cause the raw material to vaporize and generate raw
material vapor (202). The vapor is then enters the condenser (104)
for product (204) collection. The none-condensed light impurity
(205) is then passed into the cooler (105), and condensed there for
forming solid light impurity (205).
[0061] Another example of the present invention is shown in FIG.
2.
[0062] In some embodiments, the purification system 100A shown in
FIG. 2 comprises at least one sublimer (101), at least one mediated
filter (103), at least one condenser (104), and at least one cooler
(105).
[0063] The sublimer (101) is filled with raw amidinate compound
material (201A). The sublimer is heated to a predetermined
temperature, cause the raw material to vaporize and generate raw
material vapor (202). The vapor is then directed through a heat
traced pipe (106), passed through a mediated filter (103) which
serves as a physical barrier between raw material and purified
material, and then enters the condenser (104) for product (204)
collection. The none-condensed light impurity (205) is then passed
into the cooler (105), and condensed there for forming solid light
impurity (205).
[0064] In some embodiments, the purification system 100 or 100A is
operated under vacuum. The system can be connected to a vacuum
source for such purpose (not shown).
[0065] In other embodiments, the purification system 100 or 100A is
operated using carrier gas, and is under slight positive pressure.
This can be done by supplying an inert gas, such as N2, to the
system (not shown).
[0066] Yet in other embodiments, the purification system 100 or
100A is operated under vacuum and using carrier gas, as vacuum and
carrier gas can be supplied to the system at the same time.
[0067] In some embodiments, the product vapor supplied to the
condenser is cooled by condenser surface. In other embodiments, the
product vapor supplied to the condenser is cooled by a stream of
cold inert gas (121)(not shown). Furthermore, the cold inert gas
stream can be introduced through a distribution plate to form
fluidized bed. Either way, the purified product (204) is collected
in the condenser.
[0068] In some embodiments, the light impurity vapor (205) can pass
the condenser by maintaining the condenser at high temperature at
the beginning of the process, i.e., the same temperature as the
sublimer. Once all the light impurities have been vaporized and
passed through the condenser, the condenser temperature is reduced
to cumulate product.
[0069] In other embodiments when cooling gas is used to condense
the product, the condenser temperature can be maintained at a fix
level under which the impurity vapor pressure is higher than the
impurity concentration in the gaseous phase, and hence no impurity
will condense in the condenser.
[0070] In some embodiments, the impurity vapor (205) supplied to
the cooler is cooled by cooler surface. In other embodiments, the
impurity vapor supplied to the cooler is cooled by a stream of cold
inert gas (122) (not shown). Either way, the light impurity (205)
is collected in the cooler.
[0071] In some embodiments, deep vacuum (<1 torr abs) is used
for operation. The typical operation temperature for Zone 1 (see
FIG. 1) is between 60.degree. C. to 200.degree. C., between
100.degree. C. to 180.degree. C., or between 120.degree. C. to
160.degree. C. The typical startup operation temperature for Zone 2
is between 80.degree. C. to 200.degree. C., between 100.degree. C.
to 180.degree. C., or between 120.degree. C. to 160.degree. C., to
remove the light impurities. After the light impurities are
removed, the typical operation temperature for Zone 2 is between
20.degree. C. to 100.degree. C., 20.degree. C. to 80.degree. C., or
between 20.degree. C. to 60.degree. C. The typical operation
temperature for zone 3 is below 30.degree. C. at any given
time.
[0072] In some embodiments, fluidized bed is used in condenser for
better solid product uniformity. One key element to achieve the
above mentioned yield and economic aspect is to control the ratio
of inlet fluidizing gas to the inlet amidinate compound vapor at
the bottom of the condenser. It is important to keep the ratio low,
so carryover or product by the gas is limited. Since this gas
stream is also a cooling source for the inlet vapor, there is a
lower limit for the ratio according to mass and heat balance. In
general, the fluidizing gas will be heated majorly by the latent
heat released from crystallization. Ideally, in the above mentioned
temperature ranges, and ambient temperature N.sub.2 gas is
used.
[0073] Yet another key to achieve good crystal growth and high
yield is to feed the condenser with high concentration of vapor.
This can be achieved by providing high temperature to the sublimer,
or limiting the carrying gas supplied to the sublimer. Combination
of both options is preferred. In operation, it is preferable to
keep the carrying gas to vapor boil up ratio to be <10:1,
preferable <5:1, and more preferable <2:1, in molar unit. The
sublimer should be heated to the upper limit mentioned above,
depending on the operation pressure. That way, with high vapor
concentration in the feed, less process residence time is achieved
for the same amount of raw material, leading to less carryover of
material as the total amount of gas passed through is reduced. In
another embodiment lanthanide formamidinate is dissolved in inert
solvent and the solution is eluted via adsorbent bed filled with
inert adsorbent with high affinity for halide. Solvent is removed
from purified lanthanide formamidinate and lanthanide formamidinate
is further purified by the methods described above.
[0074] In certain embodiments, delivery systems or vessels are
provided for depositing lanthanide-containing film comprises
lanthanide cyclopentadienyl or lanthanide amidinate complex
containing <10.0 ppm, preferably <5.0 ppm and more preferably
<2.5 ppm of Br; and <20.0 ppm, preferably <10.0 ppm of all
halide impurity combined.
[0075] The vessel may be connected to deposition equipment known in
the art by use of a valved closure and a sealable outlet
connection.
[0076] Most preferably, the vessels may be constructed of high
purity materials, including stainless steel, glass, fused quartz,
polytetraflurorethylene, PFA.RTM., FEP.RTM., Tefzel.RTM. and the
like. The vessels may be sealed with one or more valves. The
headspace of the vessel is preferably filled with a suitable gas
such as nitrogen, argon, helium or carbon monoxide.
EXAMPLES
Example 1
Vacuum Sublimation with Raw Lanthanum Formamidinate La(FAMD).sub.3
Having R.sup.1 Hydrogen, R.sup.2=R.sup.3=Iso-Propyl Using
Purification System 100
[0077] The purification system 100 shown in FIG. 1 was used.
[0078] 600 gram of raw lanthanum formamidinate La(FAMD).sub.3
material was purchased from Strem Chemicals Inc., 7 Muliken Way,
Newburyport, Mass. and placed into the sublimer 101. The halides
and trace metals in the raw material were measured by Ion
chromatography (IC) and were listed in Table I.
[0079] The system was evacuated to <0.5 torr abs pressure.
[0080] The sublimer was heated to 70.degree. C. The condenser was
heated to 70.degree. C. for the first 5 hours. After 5 hours the
sublime was heated to 160.degree. C. and the condenser was run at
room temperature (RT 20 to 25.degree. C.) where the amidinate
compound was condensed. The cooler was maintained at room
temperature all the time
TABLE-US-00001 TABLE I Raw Purified La(FAMD).sub.3 Assay 99.7 wt. %
99.9 wt. % Chloride 5.7 ppm 1.8 ppm Bromide 583 ppm 19.8 ppm Li [
No Gas ] 0.01 0.01 Na [ No Gas ] 0.05 0.04 Mg [ No Gas ] 0.01 0.01
Al [ No Gas ] 0.01 0.01 K [ H2 ] 0.08 0.1 Ca [ H2 ] 0.01 0.13 Ti [
No Gas ] 0.01 0.01 Cr [ H2 ] 0.02 0.03 Mn [ No Gas ] 0.01 0.01 Fe
[H2 ] 0.02 0.06 Co [ No Gas ] 0.01 0.01 Ni [ No Gas ] 0.01 0.01 Cu
[ No Gas ] 0.01 0.02 Zn [ No Gas ] 0.01 0.07
[0081] The process was stopped after 24 hours.
[0082] 197 gram of product was collected.
[0083] The halides and trace metals in the product were measured by
Ion chromatography (IC), and listed in Table I.
[0084] The results indicated that sublimation reduced halide
contents. However, chloride was around 1 ppm and bromide
concentration was above 50 ppm.
[0085] The results also showed that the system was not efficient to
reduce trace metals. Please notice the low level of the trace
metals initially contained in the raw material.
Example 2
Vacuum Sublimation of Raw Lanthanum Formamidinate La(FAMD).sub.3
Having R.sup.1=Hydrogen, R.sup.2=R.sup.3=Iso-Propyl Using
Purification System 100A
[0086] The purification system 100A shown in FIG. 2 was used.
[0087] 193 grams of raw La(FAMD)3 material was purchased from Strem
Chemicals Inc., 7 Muliken Way, Newburyport, Mass. and placed into
sublimer. The halides and trace metals in the raw material were
measured by Ion chromatography (IC) and were listed in Table 2.
TABLE-US-00002 TABLE II Raw Product La(FAMD).sub.3 Assay 99.72%
99.8% Chloride 5.7 ppm 0.9 ppm Bromide 563.8 ppm 1.0 ppm Li [ No
Gas] 0.01 0.01 Na [ No Gas] 2.19 0.04 Mg [ No Gas] 0.05 <0.03 Al
[ No Gas] 0.09 0.03 K [ H2 ] 0.08 0.04 Ca [ H2 ] 0.14 <0.08 Ti [
No Gas] <0.03 <0.03 Cr [ H2 ] 0.09 0.02 Mn [ No Gas] 0.01
0.01 Fe [ H2] 0.4 0.07 Co [ No Gas] <0.02 <0.02 Ni [ No Gas]
<0.03 <0.03 Cu [ No Gas] 0.05 0.02 Zn [ No Gas] 0.06
<0.05
[0088] A glass coarse fritted disc with porosity 40-60 micron was
purchased from Chemglass Life Science LLC, 3800 N Mill Rd,
Vineland, N.J. 08360 and used as the mediated filter 103.
[0089] The system was evacuated to <0.5 torr abs pressure.
[0090] The sublimer was heated to 140.degree. C. The filter was
heated to 200.degree. C. The condenser was heated to 140.degree. C.
for the first 24 hours, and then reduced to room temperature where
the amidinate compound was condensed. The cooler was maintained at
room temperature all the time.
[0091] The process was stopped as the filter clogged the passage,
usually after 48 hours.
[0092] 40 grams of product was collected. The halides and trace
metals in the product were measured by Ion chromatography (IC) in
Table II.
[0093] The results indicated that chloride was effectively removed
below 1 ppm by using system described in FIG. 2 and bromide was
reduced to 1 ppm as well.
[0094] The results also showed that there was a consistency of the
reduction of the trace metals, considering the low level of the
trace metals initially contained in the raw material. The system
used in this example was more effective to reduce the trace
metals.
[0095] While the principles of the claimed invention have been
described above in connection with preferred embodiments, it is to
be clearly understood that this description is made only by way of
example and not as a limitation of the scope of the claimed
invention.
* * * * *