U.S. patent application number 13/736125 was filed with the patent office on 2013-05-23 for tellurium (te) precursors for making phase change memory materials.
This patent application is currently assigned to AIR PRODUCTS AND CHEMICALS, INC.. The applicant listed for this patent is Air Products and Chemicals, Inc.. Invention is credited to Thomas Richard Gaffney, Manchao Xiao.
Application Number | 20130129603 13/736125 |
Document ID | / |
Family ID | 39790835 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130129603 |
Kind Code |
A1 |
Xiao; Manchao ; et
al. |
May 23, 2013 |
Tellurium (Te) Precursors for Making Phase Change Memory
Materials
Abstract
Tellurium (Te)-containing precursors, Te containing chalcogenide
phase change materials are disclosed in the specification. A method
of making Te containing chalcogenide phase change materials using
ALD, CVD or cyclic CVD process is also disclosed in the
specification in which at least one of the disclosed tellurium
(Te)-containing precursors is introduced to the process.
Inventors: |
Xiao; Manchao; (San Diego,
CA) ; Gaffney; Thomas Richard; (Carlsbad,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Air Products and Chemicals, Inc.; |
Allentown |
PA |
US |
|
|
Assignee: |
AIR PRODUCTS AND CHEMICALS,
INC.
Allentown
PA
|
Family ID: |
39790835 |
Appl. No.: |
13/736125 |
Filed: |
January 8, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12100824 |
Apr 10, 2008 |
8377341 |
|
|
13736125 |
|
|
|
|
60913798 |
Apr 24, 2007 |
|
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Current U.S.
Class: |
423/508 ;
427/255.28; 427/419.8; 427/535 |
Current CPC
Class: |
C07B 2200/05 20130101;
C23C 16/305 20130101; H01L 21/02365 20130101; H01L 45/06 20130101;
C07B 59/004 20130101; H01L 21/02562 20130101; H01L 45/1616
20130101; C01B 19/002 20130101; C23C 16/06 20130101; C23C 16/45525
20130101; C07C 395/00 20130101; H01L 45/144 20130101; C23C 16/56
20130101 |
Class at
Publication: |
423/508 ;
427/419.8; 427/535; 427/255.28 |
International
Class: |
C23C 16/06 20060101
C23C016/06; C23C 16/56 20060101 C23C016/56; C01B 19/00 20060101
C01B019/00 |
Claims
1. A process of depositing Te containing chalcogenide phase change
material on a substrate, comprising steps of: depositing a Te
precursor comprising an organotellurol having a general structure
of: R--Te--R' wherein R is selected from the group consisting of an
alkyl group or an alkenyl group having 1 to 10 carbons in linear,
branched, or cyclic form; an aromatic group having
C.sub.6-C.sub.12; a dialkylamino group; an organosilyl group; and
an organogermyl; and R' is selected from the group consisting of
hydrogen and deuterium; depositing a Ge precursor comprising
aminogermanes having a general structure of:
(R.sup.1R.sup.2N).sub.4Ge wherein R.sup.1 and R.sup.2 are alkyl
groups having 1 to 10 carbons in linear, branched, or cyclic form;
and depositing a Sb precursor comprising aminostibanes having a
general structure of: (R.sup.1R.sup.2N).sub.3Sb wherein R.sup.1 and
R.sup.2 are alkyl groups having 1 to 10 carbons in linear,
branched, or cyclic form; and
2. The process of claim 1, wherein the organotellurol is selected
from the group consisting of N-Butyltellurol-D and
T-Butyltellurol-D.
3. The process of claim 1, wherein the process further comprising a
step of introducing hydrogen or hydrogen plasma after each step of
depositing; or after all three steps of depositing.
4. The process of claim 1, wherein at least two depositing steps
are carried out concurrently.
5. The process of claim 1, wherein the depositing is carried out by
a process selected from the group consisting of ALD, CVD, and
cyclic CVD process.
6. The process of claim 2, wherein the depositing is carried out by
a process selected from the group consisting of ALD, CVD, and
cyclic CVD process.
7. A Te containing chalcogenide phase change material synthesized
by the process of claim 5.
8. A Te containing chalcogenide phase change material synthesized
by the process of claim 6.
9. A process of depositing Te containing chalcogenide phase change
material on a substrate, comprising steps of: depositing a Te
precursor comprising a Te-containing composition having a general
structure of: R''.sub.2Te wherein R'' is selected from the group
consisting of hydrogen and deuterium; depositing a Ge precursor
comprising aminogermanes having a general structure of:
(R.sup.1R.sup.2N).sub.4Ge wherein R.sup.1 and R.sup.2 are alkyl
groups having 1 to 10 carbons in linear, branched, or cyclic form;
and depositing a Sb precursor comprising aminostibanes having a
general structure of: (R.sup.1R.sup.2N).sub.3Sb wherein R.sup.1 and
R.sup.2 are alkyl groups having 1 to 10 carbons in linear,
branched, or cyclic form.
10. The process of claim 9, wherein the process further comprising
a step of introducing hydrogen or hydrogen plasma after each step
of depositing.
11. The process of claim 9, wherein the process further comprising
a step of introducing hydrogen or hydrogen plasma after the three
steps of depositing.
12. The process of claim 9, wherein at least two depositing steps
are carried out concurrently.
13. The process of claim 9, wherein the depositing is carried out
by a process selected from the group consisting of ALD, CVD, and
cyclic CVD process.
14. A Te containing chalcogenide phase change material synthesized
by the process of claim 13.
15. A process of depositing Te containing chalcogenide phase change
material on a substrate, comprising steps of: depositing a Te
precursor comprising aminotellurium by reacting tellurium
hexafluoride with ammonia; depositing a Ge precursor comprising
aminogermanes having a general structure of:
(R.sup.1R.sup.2N).sub.4Ge wherein R.sup.1 and R.sup.2 are alkyl
groups having 1 to 10 carbons in linear, branched, or cyclic form;
and depositing a Sb precursor comprising aminostibanes having a
general structure of: (R.sup.1R.sup.2N).sub.3Sb wherein R.sup.1 and
R.sup.2 are alkyl groups having 1 to 10 carbons in linear,
branched, or cyclic form.
16. The process of claim 15, wherein the process further comprising
a step of introducing hydrogen or hydrogen plasma after each step
of depositing.
17. The process of claim 15, wherein the process further comprising
a step of introducing hydrogen or hydrogen plasma after all three
steps of depositing.
18. The process of claim 15, wherein at least two steps of
depositing are carried out sequentially or concurrently.
19. The process of claim 15, wherein the depositing is carried out
by a process selected from the group consisting of ALD, CVD, and
cyclic CVD process.
20. A Te containing chalcogenide phase change material synthesized
by the process claim 19.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 12/100,824, filed on Apr. 10, 2008, which
claims the benefit of priority under 35 U.S.C. .sctn. 119(e) to
earlier filed U.S. patent application Ser. No. 60/913,798, filed on
Apr. 24, 2007. The disclosures of those applications are hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] Phase-change materials exist in a crystalline state or an
amorphous state according to temperature. A phase-change material
has a lower resistance and a more ordered atomic arrangement in a
crystalline state than in an amorphous state. A phase-change
material can be reversibly transformed from the crystalline state
to the amorphous state based on an operating temperature. Such
characteristics, that is, reversible phase change and different
resistances of different states, are applied to newly proposed
electronic devices, a new type of nonvolatile memory devices,
phase-change random access memory (PRAM) devices. A resistance of a
PRAM may vary based on a state (e.g., crystalline, amorphous, etc.)
of a phase-change material included therein.
[0003] Various types of phase-change material can be used for
memory devices, the most commonly used phase change materials are
ternary composition of chalcogenides of group 14 and group 15
elements, such as germanium-antimony-tellurium compounds, commonly
abbreviated as GST. The solid phases of GST can rapidly change from
crystalline to amorphous or vise versa upon heating and cooling
cycles. The amorphous GST has relatively higher electric resistance
and the crystalline GST has relatively lower electric
resistance.
[0004] Currently, Physical Vapor Deposition (PVD) processes, or
spattering, are used in the manufacture of re-writable optical
disks to coat a thin layer of phase change material on the plastic
substrates. However, the PVD processes are not suitable for
electronic devices due to film growth control and film properties.
To make PRAM, Chemical Vapor Deposition (CVD), or Atomic Layer
Deposition (ALD) techniques are used to deposit a thin film of GST
on the substrate of silicon. The development of phase-change memory
devices raises the need for ALD/CVD processes with proper
precursors for low temperature deposition.
BRIEF SUMMARY OF THE INVENTION
[0005] The present invention satisfies the need by providing the
tellurium-containing compounds as Te precursors for deposition of
ternary germanium-antimony-tellurium films by low temperature ALD,
CVD or cyclic CVD processes.
[0006] A Te containing composition is disclosed in the
specification. The Te containing composition comprises deuterated
an organotellurol having a general structure of: [0007] R--Te--D
wherein R is selected from the group consisting of an alkyl group
or an alkenyl group having 1 to 10 carbons in linear, branched, or
cyclic form; an aromatic group having C.sub.6-C.sub.12; a
dialkylamino group; an organosilyl group; an organogermyl; and D is
deuterium.
[0008] A Te containing chalcogenide phase change material is
disclosed in the specification. The Te containing chalcogenide
phase change material is prepared by depositing a Te precursor
selected from the group consisting of [0009] (a) an organotellurol
having a general structure of: [0010] R-Te-R' [0011] wherein R is
selected from the group consisting of an alkyl group or an alkenyl
group having 1 to 10 carbons in linear, branched, or cyclic form;
an aromatic group having C.sub.6-C.sub.12; a dialkylamino group; an
organosilyl group; and an organogermyl; and R' is selected from the
group consisting of hydrogen and deuterium; [0012] (b) a
composition having a general structure of: R''.sub.2Te wherein R''
is selected from the group consisting of hydrogen and deuterium;
and [0013] (c) tellurium hexafluoride.
[0014] A process of depositing Te containing chalcogenide phase
change material on a substrate is also disclosed in the
specification. The process comprises steps of:
[0015] depositing a Te precursor comprising a Te-containing
composition selected from the group of: [0016] (a) an
organotellurol having general structure of: [0017] R--Te--R' [0018]
wherein R is selected from the group consisting of an alkyl group
or an alkenyl group having 1 to 10 carbons in linear, branched, or
cyclic form; an aromatic group having C.sub.6-C.sub.12; a
dialkylamino group; an organosilyl group; and an organogermyl; and
R' is selected from the group consisting of hydrogen and deuterium;
[0019] (b) a general structure of: [0020] R''.sub.2Te [0021]
wherein R'' is selected from the group consisting of hydrogen and
deuterium; and [0022] (c) tellurium hexafluoride reacting with
ammonia; depositing a Ge precursor comprising aminogermanes having
a general structure of: [0023] (R.sup.1R.sup.2N).sub.4Ge [0024]
wherein R.sup.1 and R.sup.2 are alkyl groups having 1 to 10 carbons
in linear, [0025] branched, or cyclic form; and
[0026] depositing a Sb precursor comprising aminostibanes having a
general structure of: [0027] (R.sup.1 R.sup.2N).sub.3Sb
[0028] wherein R.sup.1 and R.sup.2 are alkyl groups having 1 to 10
carbons in linear, branched, or cyclic form.
[0029] The three deposition steps in the process can be carried out
sequentially in any order or concurrently. Or, any two of three
deposition steps can be carried out concurrently. The process is
carried out at 100-400.degree. C. by ALD, CVD, or cyclic CVD
processes.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The present invention is related to selected tellurium
compounds as Te precursors, and using the selected tellurium
compounds along with aminogemanium and aminoantimony compounds, in
a low temperature process to produce ternary
germanium-antimony-tellurium films via ALD, CVD or cyclic CVD
processes.
[0031] In one embodiment of the present invention, the Te precursor
for low temperature deposition process comprises hydrogen telluride
(H.sub.2Te). Aminometal compounds are reactive toward hydrolysis.
Hydrogen chalcogenides are all more acidic than water. The
reactions of aminogermanes and aminoantimony with hydrogen
telluride form metal tellurides at low temperature (<250.degree.
C.).The deposition of tetrakis(dimethylamino)germane,
(Me.sub.2N).sub.4Ge, and tris(dimethylamino)antimony,
(Me.sub.2N).sub.3Sb, followed by the treatment with hydrogen
telluride is a suitable approach for ALD or CVD processes of making
GST films for phase change memory applications. Hydrogen telluride
is a gaseous compound with a boiling point of -4.degree. C. It is
unstable above 0.degree. C., and it decomposes into elemental
tellurium and hydrogen. To overcome this problem, hydrogen
telluride can be produced by in situ generation, and immediately
introduced into the reaction chamber.
##STR00001##
[0032] In another embodiment of the present invention, the Te
precursor comprises deuterium telluride (D.sub.2Te). Deuterium is
the heavier isotope of hydrogen (where the nucleus has an added
neutron). Deuterium telluride has improved thermal stability,
compared with the corresponding regular hydrogen telluride.
[0033] As more thermally stable tellurium compounds,
organotellurols and deuterated organotellurols are disclosed as
more suitable tellurium precursors for ternary
germanium-antimony-tellurium film depositions.
[0034] In another embodiment of the present invention, the Te
precursor for low temperature deposition process comprises
organotellurols. Organotellurols have acidic Te-H bonds, which are
highly reactive to the Ge--N and Sb--N bonds in the corresponding
aminometal compounds. Te--Ge and Te--Sb bonds form at relatively
low temperature, with the volatile amines as leaving compounds. The
reaction is illustrated in the following scheme:
##STR00002##
[0035] The Te precursor comprising organotellurols has a general
formula of [0036] R--Te--R' where R is an alkyl group or alkenyl
group having 1 to 10 carbons in linear, branched, or cyclic form;
or an aromatic group having C.sub.6-C.sub.12, such as phenyl; or a
dialkylamino group; or an organosilyl group; or an organogermyl
group; R' is hydrogen or deuterium.
[0037] Alkyl tellurols are the preferred tellurium precursors. They
are volatile liquids and can be delivered by vapor draw or direct
liquid injection methods. T-Butyltellurol has a weak Te--C bond
with a bond energy of 26 kcal/mole. The t-butyl group can be
cleaved at relatively low temperature. This helps to reduce the
carbon content in the resulting GST films.
[0038] Deuterated organotellurols have improved thermal stability,
compared with the corresponding regular organotellurols, resulting
in longer shelf life and wider process windows. Due to the primary
kinetic isotope effect, Te--D bond is more stable than Te--H bond.
Therefore, deuterated organotellurols have less tendency to
decompose during storage and delivery, while maintaining the
similar chemical reactivity to form tellurides with germanium and
antimony.
[0039] Examples of Te precursors comprising deuterated
organotellurols are N-Butyltellurol-D and T-Butyltellurol-D, where
"D" is deuterium.
[0040] In another embodiment of the present invention, the Te
precursor comprises tetrakis(dialkylamino)tellurium, wherein, the
alkyl group is independently selected from the group consisting of
methyl, ethyl, propyl, isopropyl, butyl, and t-butyl.
[0041] The Te precursor comprising tetrakis(dimethylamino)tellurium
can be mixed with tetrakis(dimethylamino)germanium
(Me.sub.2N).sub.4Ge and tris(dimethylamino)stilbane to form uniform
solutions in desired molar ratios. Such a solution is introduced to
the deposition chamber by direct liquid injection methods. The
chemicals are deposited on the surface of a heated substrate. The
following reduction reaction by hydrogen or hydrogen plasma removes
the amino groups and forms a GST layer with the proper elemental
ratio. These steps form a cycle for ALD or cyclic CVD process.
##STR00003##
[0042] In yet another embodiment of the present invention, the Te
precursor comprises tellurium hexafluoride. Tellurium hexafluoride
TeF.sub.6 is a colorless gas with a boiling point of -38.degree. C.
Unlike the sulfur analog, tellurium hexafluoride is not chemically
inert. This can be attributed to the greater availability of the d
orbital and perhaps the availability of the f orbital, which
neither sulfur nor selenium has access to.
[0043] In another embodiment of the present invention, Te
containing chalcogenide phase change material is prepared by
depositing a Te precursor selected from any of previous disclosed
embodiments, via any known deposition method, such as by ALD, CVD,
or cyclic CVD processes.
[0044] In yet another embodiment of the present invention, the
process of making a Te-containing chalcogenide phase change
material, may employ depositing a Te precursor from any of previous
disclosed embodiments with a Ge precursor and a Sb precursor via
any known deposition method, such as by ALD, CVD, or cyclic CVD
processes.
[0045] Examples of a Ge precursor and a Sb precursor are
aminogermanes and aminostibanes having the general structures of:
[0046] (R.sup.1R.sup.2N).sub.4Ge and (R.sup.1R.sup.2N).sub.3Sb
Where R.sup.1 and R.sup.2 are independently alkyl groups having 1
to 10 carbons in chain, branched, or cyclic form.
[0047] For example, as a tellurium precursor, tellurium
hexafluoride can react with ammonia in a deposition chamber to form
aminotellurium, which may subsequently react with aminogermanes and
aminostibanes, followed by hydrogen reduction to generate GST films
on a substrate. [0048]
TeF.sub.6+NH.sub.3---->[Te(NH.sub.2).sub.n]+NH.sub.4F
[0049] In the process for making the GST thin films, three
precursors can be deposited sequentially. Any one of the three
precursors, such as the Ge precursor is deposited on the surface of
a heated substrate that has a suitable temperature for the chemical
reaction. After a purging/cleaning step, such as by flowing inert
gas, the second precursor, such as the Sb precursor is deposited on
the surface of the substrate having Ge thin layer. After another
purging/cleaning step, the last precursor, such as the Te precursor
is deposited on the substrate having Ge and Sb thin layer. Any one
of the three precursors can be the first or the second or the third
precursors for the process. For the purpose of the present
invention, depositing on a substrate includes not only deposition
directly on the substrate itself, but also deposition on one at the
other of the three reactants already deposited on the
substrate.
[0050] Alternatively, the deposition process can deposit any two of
the three precursors concurrently, or all three precursors
concurrently.
[0051] In addition, the deposition process can be repeated to make
multi-layer films.
[0052] The film deposition can be carried out at 100-400.degree.
C.
Working Examples
[0053] In preparing the Te precursor for lower temperature
deposition, any of the various known methods, may be employed.
Among the known methods, a method of preparing the Te precursor
according to embodiments of the examples of the present invention
is described as follows.
Example I
Synthesis of N-Butyltellurol-D
[0054] 6.4 g (0.05 mol) 200 mesh tellurium powder, 100 ml diethyl
ether, and 20 ml 2.5 M n-butyllithium in hexane were added to a 250
ml flask. At 0.degree. C., the mixture was stirred for 8 hours. All
black powder of tellurium disappeared and a muddy color precipitate
was formed. To this mixture, 5.4 g (0.05 mol) trimethylchlorosilane
was added. The mixture was allowed to warm up to room temperature.
After stirring for 2 hours, 2.0 g (0.06 mol) deuterated methanol
(MeOD) was added slowly. After stir for 1 hour, the mixture was
filtered under inert atmosphere. The solvent and by product
methoxytrimethylsilane were removed by distillation. A vacuum
distillation gave N-Butyltellurol-D. The boiling point is
85.degree. C./100 mmHg.
Example II
Synthesis of T-Butyltellurol-D
[0055] 12.8 g (0.10 mol) 200 mesh tellurium powder, 250 ml diethyl
ether, and 50 ml 2.0 M t-butylmagnesium chloride solution in
diethyl ether were added to a 500 ml flask. At room temperature,
the mixture was stirred for 24 hours. All black powder of tellurium
disappeared and a light gray color precipitate was formed. The
mixture was cooled to -50.degree. C. with a dry ice bath. To this
mixture, 10.0 g (0.21 mol) deuterated ethanol (EtOD) was added
slowly. The mixture was allowed to warm up to room temperature.
After stirring for 2 hours, the mixture was filtered under inert
atmosphere. The solvent ether was removed by distillation. A vacuum
distillation gave T-Butyltellurol-D. The boiling point is
65.degree. C./100 mmHg.
[0056] The embodiments of this invention listed above, including
the working example, are exemplary of numerous embodiments that may
be made of this invention. It is contemplated that numerous other
configurations of the process may be used, and the materials used
in the process may be elected from numerous materials other than
those specifically disclosed.
* * * * *