U.S. patent application number 09/827973 was filed with the patent office on 2001-09-13 for semiconductor processing method of forming a conductive line, and buried bit line memory circuitry.
Invention is credited to DeBoer, Scott Jeffrey, Hu, Yongjun Jeff, Pan, Pai-Hung.
Application Number | 20010021579 09/827973 |
Document ID | / |
Family ID | 23805009 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010021579 |
Kind Code |
A1 |
Hu, Yongjun Jeff ; et
al. |
September 13, 2001 |
Semiconductor processing method of forming a conductive line, and
buried bit line memory circuitry
Abstract
The invention includes buried bit line memory circuitry, methods
of forming buried bit line memory circuitry, and semiconductor
processing methods of forming conductive lines. In but one
implementation, a semiconductor processing method of forming a
conductive line includes forming a silicon comprising region over a
substrate. A TiN.sub.x comprising layer is deposited over the
silicon comprising region, where "x" is greater than 0 and less
than 1. The TiN.sub.x comprising layer is annealed in a nitrogen
containing atmosphere effective to transform at least an outermost
portion of the TiN.sub.x layer over the silicon comprising region
to TiN. After the annealing, an elemental tungsten comprising layer
is deposited on the TiN and at least the elemental tungsten
comprising layer, the TiN, and any remaining TiN.sub.x layer is
patterned into conductive line. In one implementation, a method
such as the above is utilized in the fabrication of buried bit line
memory circuitry. In one implementation, the invention comprises
buried bit line memory circuitry fabricated by the above and other
methods.
Inventors: |
Hu, Yongjun Jeff; (Boise,
ID) ; Pan, Pai-Hung; (Boise, ID) ; DeBoer,
Scott Jeffrey; (Boise, ID) |
Correspondence
Address: |
WELLS ST JOHN ROBERTS GREGORY AND MATKIN
SUITE 1300
601 W FIRST AVENUE
SPOKANE
WA
992013828
|
Family ID: |
23805009 |
Appl. No.: |
09/827973 |
Filed: |
April 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09827973 |
Apr 5, 2001 |
|
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09454536 |
Dec 6, 1999 |
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Current U.S.
Class: |
438/625 ;
257/E21.582; 257/E21.593; 257/E21.657; 257/E21.658;
257/E27.088 |
Current CPC
Class: |
H01L 27/10888 20130101;
H01L 21/76838 20130101; H01L 27/10885 20130101; H01L 21/76889
20130101; H01L 27/10814 20130101 |
Class at
Publication: |
438/625 |
International
Class: |
H01L 021/4763 |
Claims
1. A method of forming buried bit line memory circuitry comprising:
forming a word line having a pair of opposing source/drain regions
on a substrate; forming a silicon comprising region over and in
electrical connection with one of the pair of source/drain regions;
depositing a TiN.sub.x comprising layer over the silicon comprising
region, where "x" is greater than 0 and less than 1; annealing the
TiN.sub.x comprising layer in a nitrogen containing atmosphere
effective to transform at least an outermost portion of the
TiN.sub.x layer over the silicon comprising region to TiN; after
the annealing, forming an elemental tungsten comprising layer on
the TiN and patterning at least the elemental tungsten comprising
layer, the TiN, and any remaining TiN.sub.x layer into a bit line
in electrical connection with the one source/drain region; and
forming a capacitor received at least partially outwardly of the
bit line and in electrical connection with another of the pair of
source/drain regions.
2. The method of claim 1 wherein the annealing reacts an innermost
portion of the TiN.sub.x layer with silicon of the silicon
comprising region to form a silicide.
3. The method of claim 2 wherein the silicide comprises
TiSi.sub.yN.sub.x, where "y" is greater than 0 and less than 2, and
"z" is less than or equal to 1.
4. The method of claim 1 wherein the annealing transforms at least
an outermost portion of the TiN.sub.x layer not over the silicon
comprising region to TiN.
5. The method of claim 1 wherein the annealing transforms only an
outermost portion of the TiN.sub.x comprising layer over the
silicon region to TiN, and at least an outermost portion of the
TiN.sub.x layer not over the silicon comprising region to TiN.
6. The method of claim 1 wherein the silicon comprising region
comprises polysilicon.
7. The method of claim 1 wherein "x" ranges from 0.2 to 0.8.
8. The method of claim 1 wherein "x" ranges from 0.5 to 0.6.
9. The method of claim 1 wherein the nitrogen containing atmosphere
comprises at least one of N.sub.2 and NH.sub.3.
10. The method of claim 1 wherein the annealing comprises a
temperature of at least 400.degree. C.
11. The method of claim 1 wherein in the annealing comprises
RTP.
12. The method of claim 1 wherein the annealing is conducted in
situ in a chamber within which the elemental tungsten comprising
layer is formed by depositing.
13. A method of forming buried bit line memory circuitry
comprising: forming a word line having a pair of opposing
source/drain regions on a substrate; forming an insulating layer
over the word line and the source/drain regions; forming a
polysilicon comprising plug in electrical connection with one of
the pair of source/drain regions through the insulating layer;
depositing a TiN.sub.x comprising layer over the insulating layer
and the polysilicon comprising plug, where "x" is greater than 0
and less than 1; annealing the TiN.sub.x comprising layer in a
nitrogen containing atmosphere effective to transform at least an
outermost portion of the TiN.sub.x layer to TiN and at least an
outermost portion of the polysilicon comprising plug to a silicide
from titanium of the TiN.sub.x comprising layer; after the
annealing, forming an elemental tungsten comprising layer on the
TiN and patterning the elemental tungsten comprising layer, the
TiN, and any remaining TiN.sub.x layer into a bit line in
electrical connection with the one source/drain region; and forming
a capacitor received at least partially outwardly of the bit line
and in electrical connection with another of the pair of
source/drain regions.
14. The method of claim 13 wherein the silicide comprises
TiSi.sub.yN.sub.z, where "y" is greater than 0 and less than 2, and
"z" is less than or equal to 1.
15. The method of claim 13 wherein "x" ranges from 0.2 to 0.8.
16. The method of claim 13 wherein "x" ranges from 0.5 to 0.6.
17. The method of claim 13 wherein the annealing is conducted in
situ in a chamber within which the elemental tungsten comprising
layer is formed by depositing.
18. A method of forming buried bit line memory circuitry
comprising: forming a word line having a pair of opposing
source/drain regions on a substrate; forming an insulating layer
over the word line and the source/drain regions; forming a
polysilicon comprising plug in electrical connection with one of
the pair of source/drain regions through the insulating layer;
depositing a polysilicon comprising layer over the insulating layer
and the polysilicon comprising plug; depositing a TiN.sub.x
comprising layer over the polysilicon comprising layer, where "x"is
greater than 0 and less than 1; annealing the TiN.sub.x comprising
layer in a nitrogen containing atmosphere effective to transform at
least an outermost portion of the TiN.sub.x layer to TiN and react
at least an innermost portion of the TiN.sub.x layer with
polysilicon of the polysilicon comprising layer to form a silicide;
after the annealing, forming an elemental tungsten comprising layer
on the TiN and patterning the elemental tungsten comprising layer,
the TiN, the silicide and any remaining of the polysilicon
comprising layer into a bit line in electrical connection with the
one source/drain region; and forming a capacitor received at least
partially outwardly of the bit line and in electrical connection
with another of the pair of source/drain regions.
19. The method of claim 18 wherein the silicide comprises
TiSi.sub.yN.sub.z, where "y" is greater than 0 and less than 2, and
"z" is less than or equal to 1.
20. The method of claim 18 wherein "x" ranges from 0.2 to 0.8.
21. The method of claim 18 wherein "x" ranges from 0.5 to 0.6.
22. The method of claim 18 wherein the annealing is conducted in
situ in a chamber within which the elemental tungsten comprising
layer is formed by depositing.
23. A semiconductor processing method of forming a conductive line
comprising: forming a silicon comprising region over a substrate;
depositing a TiN.sub.x comprising layer over the silicon comprising
region, where "x" is greater than 0 and less than 1; annealing the
TiNhd x comprising layer in a nitrogen containing atmosphere
effective to transform at least an outermost portion of the
TiN.sub.x layer over the silicon comprising region to TiN; after
the annealing, depositing an elemental tungsten comprising layer on
the TiN and patterning at least the elemental tungsten comprising
layer, the TiN, and any remaining TiN.sub.x layer into conductive
line.
24. The method of claim 23 wherein the annealing reacts an
innermost portion of the TiN.sub.x layer with silicon of the
silicon comprising region to form a silicide.
25. The method of claim 24 wherein the silicide comprises
TiSi.sub.yN.sub.z, where "y" is greater than 0 and less than 2, and
"z" is less than or equal to 1.
26. The method of claim 23 wherein the annealing transforms at
least an outermost portion of the TiN.sub.x layer not over the
silicon comprising region to TiN.
27. The method of claim 23 wherein the annealing transforms only an
outermost portion of the TiN.sub.x comprising layer over the
silicon region to TiN, and at least an outermost portion of the
TiN.sub.x layer not over the silicon comprising region to TiN.
28. The method of claim 23 wherein "x" ranges from 0.2 to 0.8.
29. The method of claim 23 wherein the annealing is conducted in
situ in a chamber within which the elemental tungsten comprising
layer is formed by depositing.
30. Buried bit line memory circuitry comprising: a word line having
a pair of opposing source/drain regions; an insulating layer
received over the word line and the source/drain regions; a
polysilicon comprising plug extending through the insulating layer
in electrical connection with one of the pair of source/drain
regions, the plug comprising an outermost silicide region; a bit
line over the insulating layer and contacting the outermost
silicide region of the plug, the bit line comprising a TiN
comprising region and an outer elemental tungsten comprising
region; and a capacitor received at least partially outwardly of
the bit line and in electrical connection with another of the pair
of source/drain regions.
31. The buried bit line memory circuitry of claim 30 wherein the
silicide comprises TiSi.sub.yN.sub.z, where "y" is greater than 0
and less than 2, and "z" is less than or equal to 1.
32. The buried bit line memory circuitry of claim 30 wherein the
bit line comprises TiN.sub.x, where "x" is greater than 0 and less
than 1.
33. The buried bit line memory circuitry of claim 30 wherein the
bit line comprises TiN.sub.x, where "x" is greater than 0 and less
than 1, the TiN.sub.x being received inwardly of the TiN.
34. Buried bit line memory circuitry comprising: a word line having
a pair of opposing source/drain regions; an insulating layer
received over the word line and the source/drain regions; a
polysilicon comprising plug extending through the insulating layer
in electrical connection with one of the pair of source/drain
regions; a bit line over the insulating layer in electrical
connection with the polysilicon comprising plug and the one
source/drain region, the bit line comprising an inner silicide
region, a TiN comprising mid region and an outer elemental tungsten
comprising region; and a capacitor received at least partially
outwardly of the bit line and in electrical connection with another
of the pair of source/drain regions.
35. The buried bit line memory circuitry of claim 34 wherein the
silicide comprises TiSi.sub.yN.sub.z, where "y" is greater than 0
and less than 2, and "z" is less than or equal to 1.
36. The buried bit line memory circuitry of claim 34 wherein the
bit line comprises TiN.sub.x, where "x" is greater than 0 and less
than 1.
37. Buried bit line memory circuitry comprising: a word line having
a pair of opposing source/drain regions; an insulating layer
received over the word line and the source/drain regions; a
polysilicon comprising plug extending through the insulating layer
in electrical connection with one of the pair of source/drain
regions; a bit line over the insulating layer in electrical
connection with the polysilicon comprising plug and the one
source/drain region, the bit line comprising a TiN.sub.x region,
where "x" is greater than 0 and less than 1, and an outer elemental
tungsten comprising region; and a capacitor received at least
partially outwardly of the bit line and in electrical connection
with another of the pair of source/drain regions.
38. The buried bit line memory circuitry of claim 37 wherein the
bit line comprises an inner silicide region.
39. The buried bit line memory circuitry of claim 38 wherein the
silicide comprises TiSi.sub.yN.sub.z, where "y" is greater than 0
and less than 2, and "z" is less than or equal to 1.
Description
TECHNICAL FIELD
[0001] This invention relates to buried bit line memory circuitry,
to methods of forming buried bit line memory circuitry, and to
semiconductor processing methods of forming conductive lines.
BACKGROUND OF THE INVENTION
[0002] Semiconductor circuitry fabrication is ever attempting to
make denser and smaller circuit components. One type of circuitry
where this is occurring is in the design and fabrication of memory
circuitry, for example in buried bit line memory circuitry. One
type of memory circuitry employing buried bit line architecture is
dynamic random access memory (DRAM). Such circuitry typically
includes a series of bit lines and word lines wherein at least a
majority portion of the capacitors are formed elevationally above
or outwardly of the bit lines.
[0003] A parasitic capacitance between buried digit lines becomes
increasingly problematic as circuitry density becomes greater and
circuitry components become smaller. Accordingly, alternate designs
and materials are being considered for fabrication of the digit
lines in highly dense circuitry fabrication, for example at and
below 0.18 micron digit line width.
[0004] The invention was motivated from a desire to improve
fabrication methods and constructions associated with buried bit
line circuitry, and particularly buried bit line DRAM circuitry.
However, the artisan will appreciate applicability of the invention
to other circuitry fabrication methods and structures, with the
invention only being limited by the accompanying claims
appropriately interpreted in accordance with the doctrine of
equivalents.
SUMMARY
[0005] The invention includes buried bit line memory circuitry,
methods of forming buried bit line memory circuitry, and
semiconductor processing methods of forming conductive lines. In
but one implementation, a semiconductor processing method of
forming a conductive line includes forming a silicon comprising
region over a substrate. A TiN.sub.x comprising layer is deposited
over the silicon comprising region, where "x"0 is greater than 0
and less than 1. The TiN.sub.x comprising layer is annealed in a
nitrogen containing atmosphere effective to transform at least an
outermost portion of the TiN.sub.x layer over the silicon
comprising region to TiN. After the annealing, an elemental
tungsten comprising layer is deposited on the TiN and at least the
elemental tungsten comprising layer, the TiN, and any remaining
TiN.sub.x layer is patterned into conductive line. In one
implementation, a method such as the above is utilized in the
fabrication of buried bit line memory circuitry. In one
implementation, the invention comprises buried bit line memory
circuitry fabricated by the above and other methods.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Preferred embodiments of the invention are described below
with reference to the following accompanying drawings.
[0007] FIG. 1 is a top diagrammatic view of a buried bit line DRAM
array in accordance with but one aspect of the invention.
[0008] FIG. 2 is a sectional view of FIG. 1 taken through line
X2-X3 at one processing step in accordance with an aspect of the
invention.
[0009] FIG. 3 is a sectional view of FIG. 1 taken through line
X1-X4 at the same sequence in processing as FIG. 2.
[0010] FIG. 4 is a view of the FIG. 2 wafer fragment at a
processing step subsequent to that depicted by FIG. 2.
[0011] FIG. 5 is a view of the FIG. 3 wafer fragment at a
processing step subsequent to that depicted by FIG. 3 and
corresponding in sequence with that depicted by FIG. 4.
[0012] FIG. 6 is a view of the FIG. 4 wafer fragment at a
processing step subsequent to that depicted by FIG. 4.
[0013] FIG. 7 is a view of the FIG. 5 wafer fragment at a
processing step subsequent to that depicted by FIG. 5 and
corresponding in sequence to that depicted by FIG. 6.
[0014] FIG. 8 is an alternate embodiment wafer fragment
corresponding in section and sequence to that depicted by FIG.
6.
[0015] FIG. 9 is a view of the alternate embodiment wafer fragment
corresponding in section and sequence to that depicted by FIG.
7.
[0016] FIG. 10 is a view of the FIG. 6 wafer fragment at a
processing step subsequent to that depicted by FIG. 6.
[0017] FIG. 11 is a view of the FIG. 7 wafer fragment at a
processing step corresponding to that depicted by FIG. 10.
[0018] FIG. 12 is a view of the alternate embodiment wafer fragment
corresponding in section and sequence to that depicted by FIG.
10.
[0019] FIG. 13 is a view of the alternate embodiment wafer fragment
corresponding in section and sequence to that depicted by FIG.
11.
[0020] FIG. 14 is a view of the FIG. 10 wafer fragment at a
processing step subsequent to that depicted by FIG. 10.
[0021] FIG. 15 is a view of the FIG. 11 wafer fragment at a
processing step subsequent to that depicted by FIG. 11 and
corresponding to that depicted by FIG. 14.
[0022] FIG. 16 is a view of the alternate embodiment wafer fragment
corresponding in section and sequence to that depicted by FIG.
14.
[0023] FIG. 17 is a view of the alternate embodiment wafer fragment
corresponding in section and sequence to that depicted by FIG.
15.
[0024] FIG. 18 is a view of the FIG. 14 wafer fragment at a
processing step subsequent to that depicted by FIG. 14.
[0025] FIG. 19 is a view of the alternate embodiment wafer fragment
corresponding in section and sequence to that depicted by FIG.
18.
[0026] FIG. 20 is a view of the FIG. 19 alternate embodiment wafer
fragment at a processing step subsequent to that depicted by FIG.
19.
[0027] FIG. 21 is a view of the FIG. 20 wafer fragment at a
processing step subsequent to that depicted by FIG. 20.
[0028] FIG. 22 is an alternate embodiment view of the FIG. 20 wafer
fragment at an alternate processing step to that depicted by FIG.
21.
[0029] FIG. 23 is a perspective view of a processing reactor, with
a portion broken away for clarity, utilizable in accordance with
one of the processing steps depicted in other figures.
[0030] FIG. 24 is an elevational schematic view of one aspect of
processing in accordance with a preferred embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] This disclosure of the invention is submitted in furtherance
of the constitutional purposes of the U.S. Patent Laws "to promote
the progress of science and useful arts" (Article 1, Section
8).
[0032] A method of forming buried bit line memory circuitry is
described in conjunction with but one exemplary embodiment of
forming DRAM buried bit line memory circuitry as depicted in top
plan view in FIG. 1. Alternate buried bit line DRAM circuitry, and
alternate buried bit line memory circuitry are of course
contemplated. The description proceeds with reference to two
exemplary preferred embodiments. One of the embodiments
sequentially progresses with description relative to FIGS. 2-7,
FIG. 10, FIG. 11, FIG. 14, FIG. 15, and FIG. 18. An alternate
embodiment is shown and described with reference to FIGS. 2-5, FIG.
8, FIG. 9, FIG. 12, FIG. 13, FIG. 16, FIG. 17, and FIG. 19.
Subsequent exemplary processing in accordance with but one aspect
of the invention proceeds relative to subsequent processing of the
FIG. 19 embodiment in FIG. 20. Two exemplary alternate processings
subsequent to FIG. 20 are shown in FIGS. 21 and 22. The alternate
embodiment depictions in FIG. 8, FIG. 9, FIG. 12, FIG. 13, FIG. 16,
FIG. 17, and FIG. 19 utilize the same numerals for their
corresponding figures, with differences being indicated with the
suffix "a" or with different numerals. Alternate embodiments are of
course contemplated.
[0033] Referring initially to FIGS. 1-3, a semiconductor wafer
fragment is indicated generally with reference numeral 10. Such
comprises a bulk monocrystalline silicon substrate 12 and shallow
trench field isolation regions 14. In the context of this document,
the term "semiconductor substrate" or "semiconductive substrate" is
defined to mean any construction comprising semiconductive
material, including, but not limited to, bulk semiconductive
materials such as a semiconductive wafer (either alone or in
assemblies comprising other materials thereon), and semiconductive
material layers (either alone or in assemblies comprising other
materials). The term "substrate" refers to any supporting
structure, including, but not limited to, the semiconductive
substrates described above. Wafer fragment 10 includes word line
constructions 15, 16, 17, and 18. Each is depicted as being
comprised of a gate dielectric region, a conductively doped
polysilicon region on the gate dielectric region, a conductive
silicide region on the polysilicon region, an insulating cap on the
silicide region, and insulative anisotropically etched sidewall
spacers. Such components are merely exemplary and not depicted with
numerals.
[0034] A series of source/drain diffusion regions 19, 20 and 21 are
received proximate the illustrated word lines. Regions 19 and 21 in
the exemplary embodiment will constitute storage node contacts for
respective capacitors, while source/drain region 20 will constitute
a bit node contact. Accordingly, and by way of example only, word
line 16 can be considered as having or being associated with a pair
of opposing source/drain regions 19 and 20, and word line
construction 17 can be considered as having or being associated
with a pair of opposing source/drain regions 20 and 21.
[0035] Referring to FIGS. 4 and 5, an insulating layer 22 is
deposited over the word lines and source/drain regions. A contact
opening 23 has been formed therethrough to source/drain region 20,
filled with a conductive plugging material 24, and preferably
planarized back as shown. An exemplary and preferred material for
layer 22 is borophosphosilicate glass (BPSG). Plug 24 preferably
comprises conductively doped silicon, and more preferably
conductively doped polysilicon. Diffusion barrier layers and/or
adhesion layers might also constitute a part of plug 24, if
desired. Accordingly, such depicts but one example of forming a
polysilicon comprising plug 24 in electrical connection with a
source/drain diffusion region 20 through an insulating layer 22. In
the context of this particular embodiment, plug 24 can be
considered as a silicon comprising region in electrical connection
with source/drain region 20.
[0036] Referring to FIGS. 6 and 7, an HF preclean dip is preferably
conducted before a TiN.sub.x comprising layer 26 is deposited over
insulating layer 22 and silicon comprising region/polysilicon
comprising plug 24, where "x" is greater than 0 and less than 1.
Preferably, x ranges from 0.2 to 0.8, and even more preferably from
0.5 to 0.6. One preferred way of forming the TiN.sub.x is as
described in our co-pending U.S. patent application Ser. No.
09/026,104, filed on Feb. 19, 1998, and entitled "Asymmetric,
Double-Sided Self-Aligned Silicide and Method of Forming the Same"
having Yongjun Jeff Hu as the inventor. Another preferred method of
forming TiN.sub.x layer 26 is shown and described with reference to
FIGS. 23 and 24 utilizing a sputter deposition reactor 176. FIG. 23
depicts a broken perspective view of an exemplary process in
reactor 176 emphasizing preferred inductive coil positioning, with
other reactor components not being depicted for clarity. FIG. 24
diagrammatically depicts operation of the exemplary reactor of FIG.
23 showing target, wafer, inductive coil, and plasma generation as
will now be more specifically described.
[0037] Sputtering reactor 176 includes an inductive coil 178
mounted within a reactor chamber 177. A preferred sputter
deposition system is a Magnatron System available from Applied
Materials as an Ion Metal Plasma (IMP) Reactor.TM.. Such is capable
of retaining and DC biasing a target 180 and an RF.sub.2 biased
substrate (FIG. 24), such as for example substrate 10. In a
preferred method of forming a layer 26, a nitrogen containing
source gas and a sputtering gas are fed to reactor chamber 177. The
reactor is operated during such feeding to provide a selected
target power, inductive coil power, and substrate bias to deposit
TiN.sub.x comprising layer 26 onto substrate 10. Using the IMP
reactor, exemplary operable ranges include a substrate bias
(RF.sub.2) from 0 W (neutral) to 1000 W, an inductive coil power
(RF.sub.1) from 1.0 kW to 5.0 kW, and a target power (DC) of from
1.0 kW to 5.0 kW. A preferred nitrogen containing source gas is
N.sub.2, with a preferred sputtering gas being a noble gas, such as
Ar.
[0038] Preferred reactor temperature ranges for the processing as
depicted in FIG. 24 are from room temperature to 250.degree. C. for
backside temperature, and preferably from about 10 mTorr to about
30 mTorr. Preferred RF.sub.2 bias is from 300 W to 500 W. A largely
magnatron plasma 184 forms near target 180 for sputtering material
therefrom, with inductive coil 178 resulting in formation of a gas
plasma 182 therebeneath. A high electric field or self-bias
develops in the boundary layer or sheath between the plasma and the
substrate which accelerates the metal ions towards the substrate in
a vector generally perpendicular to the wafer surface, particularly
for increasing RF.sub.2 bias values.
[0039] In the preferred example, gas plasma 182/184 as generated
within reactor chamber 77 extends entirely between at least a
portion of target 180 and a portion of substrate 10, resulting in
deposition of layer 26 as diagrammatically shown in FIG. 24. A
specific example using the IMP reactor comprises a DC target power
of 2.0 kW, RF.sub.1 at 2.8 kW, RF.sub.2 at 0 W with argon and
nitrogen flows at 30 and 40 sccm, respectively. A preferred
thickness for layer 26 is from 150 Angstroms to 300 Angstroms.
[0040] FIGS. 8 and 9 illustrate alternate exemplary processing in
connection with a semiconductor wafer fragment 10a. Wafer fragment
10a differs from that depicted by FIGS. 6 and 7 in deposition of a
polysilicon comprising layer 25 over insulating layer 22 and
polysilicon comprising plug 24. Accordingly in the FIGS. 8 and 9
depicted embodiment, polysilicon layer 25 and polysilicon plug 24
constitute an exemplary silicon comprising region formed over and
in electrical connection with source/drain diffusion region 20. An
example thickness for layer 25 is from 500 Angstroms to 1000
Angstroms. Alternately or in addition, the combined thickness of
layers 25 and 26a preferably correspond to the total thickness of
layer 26 in the FIGS. 6 and 7 embodiment. Further preferably,
layers 25 and 26a are deposited to be roughly the same
thickness.
[0041] Referring to FIGS. 10 and 11, TiN.sub.x comprising layer 26
in one implementation is annealed in a nitrogen containing
atmosphere (with or without plasma) effective to transform at least
an outermost portion of TiN.sub.x layer 26 over silicon comprising
region 24 to stoichiometric TiN material 28. Further preferably,
such annealing is effective to transform at least an outermost
portion of polysilicon comprising plug 24 to a silicide material 30
from titanium of the TiN.sub.x comprising layer. Thus, plug 24 now
preferably comprises an outermost silicide region 30. Silicide
region 30 preferably comprises TiSi.sub.yN.sub.z, where "y" is
greater than 0 and less than 2, and "z" is less than or equal to 1.
The FIGS. 10 and 11 processing also depicts the annealing
transforming at least an outermost portion of the TiN.sub.x layer
not over silicon comprising region 24 to stoichiometric TiN.
Further, FIGS. 10 and 11 depict transformation of only an outermost
portion of the TiN.sub.x layer over silicon region 24 to TiN, and
only an outermost portion thereof not over silicon comprising
region 24 to stoichiometric TiN. In an alternate considered and
preferred embodiment, all of the TiN.sub.x layer which is not over
plug 24 is transformed to stoichiometric TiN, with some
stoichiometric TiN remaining over silicide region 30.
[0042] Preferred nitrogen containing atmospheres during annealing
comprise at least one of N.sub.2 and NH.sub.3. The annealing
preferably comprises rapid thermal processing (RTP) with a
temperature ramp rate of at least 50.degree. C. per second.
Regardless, the annealing preferably comprises a temperature of at
least 400.degree. C., and more preferably from 400.degree. C. to
750.degree. C. Processing time at the final temperature is
preferably from between 20 seconds to 100 seconds. In a reduction
to practice example, a temperature of 650.degree. C., for 60
seconds in an N.sub.2 comprising atmosphere was utilized. A RTP
reduction to practice example is to a temperature from 950.degree.
C. to 1000.degree. C.
[0043] An example plasma annealing atmosphere comprises nitrogen
and hydrogen, for example a combination of N.sub.2 and H.sub.2,
and/or NH.sub.3. Example plasma conditions include using an Applied
Materials Centura reactor, with plasma power ranging from 100 W to
1500 W, time at from 10 seconds to 240 seconds, temperature at from
300.degree. C. to 550.degree. C., pressure from 10 mTorr to 10
Torr. Exemplary processing with such parameters using both N.sub.2
and H.sub.2 comprises flow rates for each gas of from 50 sccm to
100 sccm with argon being provided at from 0 sccm to 500 sccm.
[0044] FIGS. 12 and 13 illustrate but one exemplary annealing
processing which might occur with respect to the alternate
substrate 10a embodiment. The same preferred annealing shows
TiN.sub.x layer 26a (FIGS. 8 and 9) and polysilicon layer 25 (FIGS.
8 and 9) having been transformed to an outermost stoichiometric TiN
layer 32 (FIGS. 12 and 13) and an innermost silicide layer 34
(FIGS. 12 and 13) preferably of the composition as described above.
In accordance with an aspect of the alternate embodiment, the
annealing transforms at least an outermost portion of the TiN.sub.x
layer to TiN and reacts at least an innermost portion of the
TiN.sub.x layer with polysilicon of polysilicon comprising layer 25
to form a silicide. Alternately and by way of example only, an
intermediate TiN.sub.x layer or region might also remain (not
shown). Further alternately and by way of example only, only an
outer portion of polysilicon comprising layer 25 might be converted
to a silicide, leaving an inner portion comprising polysilicon (not
shown).
[0045] Referring to FIGS. 14 and 15, and after the annealing, an
elemental tungsten comprising layer 38 (i.e., either tungsten or an
alloy of tungsten) is formed on the TiN. Such might occur by
conventional chemical vapor deposition, plasma enhanced chemical
vapor deposition, physical vapor deposition or by other methods. An
exemplary thickness is from 300 Angstroms to 500 Angstroms. In
accordance with a preferred aspect of the invention, the above
described annealing is conducted in situ in a chamber within which
the elemental tungsten comprising layer is also formed by a
deposition. An example and preferred thickness for layer 38 is from
300 Angstroms to 500 Angstroms.
[0046] FIGS. 16 and 17 depict a layer 38 deposition in accordance
with the alternate embodiment wafer fragment 10a.
[0047] Referring to FIGS. 1 and 18, elemental tungsten comprising
layer 38, TiN layer 32, and any remaining TiN.sub.x layer have been
patterned, preferably using photoresist and photolithography, into
a bit line 40 which is in electrical connection with source/drain
region 20. FIG. 19 depicts alternate -corresponding processing in
the fabrication of a bit line 40a whereby the elemental tungsten
comprising layer, the TiN, the silicide and any remaining of the
polysilicon comprising layer have been patterned into a bit line
40a in electrical connection with source/drain diffusion region 20.
The X1-X4 section view (taken from FIG. 1) of the process
corresponding to that of FIG. 18 would be the same as shown in FIG.
15. Likewise, the X2-X3 section view (taken from FIG. 1) of the
process corresponding to that of FIG. 19 would be the same as shown
in FIG. 17. Accordingly, FIG. 18 depicts buried bit line memory
circuitry wherein a bit line 40 is received over insulating layer
22 and contacts outermost silicide region 30 of plug 24, and
comprises a TiN region and an outer elemental tungsten comprising
region. Further, FIG. 19 depicts bit line 40a comprising an inner
silicide region, a TiN comprising mid region, and an outer
elemental tungsten comprising region. Further, word line 40 in
FIGS. 15 and 18 depict but one exemplary bit line comprising a
TiN.sub.x region and an outer elemental tungsten comprising
region.
[0048] Referring to FIG. 20, an insulating layer 44 (i.e.,
planarized BPSG) is formed over bit line 40a and remaining portions
of substrate 10a. Storage node/capacitor contacts 46 and 48 are
made therethrough and through insulating layer 22 to source/drain
regions 19 and 21, respectively.
[0049] Alternate exemplary processing for fabrication of capacitor
structures are shown with respect to FIGS. 21 and 22. Specifically,
FIG. 21 depicts fabrication of capacitors 50 and 52 relative to
storage node openings 46 and 48. Such could be formed, by example
only, by deposition of a storage node layer 54 which is planarized
back relative to layer 44 to provide desired isolated storage
nodes. A suitable capacitor dielectric layer 56 and cell capacitor
plate layer 58 could then be deposited thereover.
[0050] FIG. 22 depicts plugging of storage node openings 46 and 48
with a conductive plugging material 59. Then, another insulating
layer 60, (i.e., BPSG) is formed over the substrate, and container
openings 64 are provided therein. A storage node layer 54,
capacitor dielectric layer 56 and cell plate layer 58 could then be
subsequently formed as shown to produce capacitors 51 and 53.
Regardless, both such embodiments depict formation of a capacitor
received at least partially outward of the bit line and in
electrical connection with one of source/drain regions 19 and
21.
[0051] The processing and circuitry was described with respect to
DRAM circuitry. However, other memory circuitry and other circuitry
are also contemplated. For and by way of example only, the
processing includes formation of a conductive line which might be
other than a bit line.
[0052] In compliance with the statute, the invention has been
described in language more or less specific as to structural and
methodical features. It is to be understood, however, that the
invention is not limited to the specific features shown and
described, since the means herein disclosed comprise preferred
forms of putting the invention into effect. The invention is,
therefore, claimed in any of its forms or modifications within the
proper scope of the appended claims appropriately interpreted in
accordance with the doctrine of equivalents.
* * * * *