U.S. patent application number 10/621863 was filed with the patent office on 2005-01-20 for mocvd of tio2 thin film for use as feram h2 passivation layer.
This patent application is currently assigned to Sharp Laboratories of America, Inc.. Invention is credited to Barrowcliff, Robert A., Evans, David R., Hsu, Sheng Teng, Li, Tingkai, Pan, Wei.
Application Number | 20050014296 10/621863 |
Document ID | / |
Family ID | 34063079 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050014296 |
Kind Code |
A1 |
Li, Tingkai ; et
al. |
January 20, 2005 |
MOCVD OF TIO2 THIN FILM FOR USE AS FERAM H2 PASSIVATION LAYER
Abstract
A method of forming an H.sub.2 passivation layer in an FeRAM
includes preparing a silicon substrate; depositing a layer of
TiO.sub.x thin film, where 0<x<2, on a damascene structure;
plasma space etching of the Ti or TiO.sub.x thin film to form a
TiO.sub.x sidewall; annealing the TiO.sub.x side wall thin film to
form a TiO.sub.2 thin film; depositing a layer of ferroelectric
material; and metallizing the structure to form a FeRAM.
Inventors: |
Li, Tingkai; (Vancouver,
WA) ; Pan, Wei; (Vancouver, WA) ; Barrowcliff,
Robert A.; (Vancouver, WA) ; Evans, David R.;
(Beaverton, OR) ; Hsu, Sheng Teng; (Camas,
WA) |
Correspondence
Address: |
David C. Ripma
Patent Counsel
Sharp Laboratories of America, Inc.
5750 NW Pacific Rim Boulevard
Camas
WA
98607
US
|
Assignee: |
Sharp Laboratories of America,
Inc.
|
Family ID: |
34063079 |
Appl. No.: |
10/621863 |
Filed: |
July 16, 2003 |
Current U.S.
Class: |
438/3 ;
257/E21.208; 257/E21.274; 257/E21.436; 257/E21.663; 257/E27.104;
438/240 |
Current CPC
Class: |
H01L 21/31604 20130101;
H01L 29/6684 20130101; H01L 27/1159 20130101; H01L 28/57 20130101;
H01L 27/11502 20130101; H01L 27/11585 20130101; H01L 29/40111
20190801 |
Class at
Publication: |
438/003 ;
438/240 |
International
Class: |
H01L 021/00; H01L
021/8242 |
Claims
1. A method of forming an H.sub.2 passivation layer in an FeRAM,
comprising: preparing a silicon substrate, including doping to form
a P-type silicon wafer, including threshold adjustment ion
implantation, shallow trench isolation, of a gate oxide, deposition
of a polysilicon layer, ion implantation to form an N.sup.+ source
and an drain; smoothing the oxide by CMP, and patterning and
etching the polysilicon layer; depositing a layer of TiO.sub.x thin
film, where 0<x<2, on a damascene structure; plasma space
etching of the TiO.sub.x thin film to form a TiO.sub.x sidewall;
annealing the TiO.sub.x side wall thin film to form a TiO.sub.2
thin film; depositing a layer of ferroelectric material; and
metallizing to form a FeRAM.
2. The method of claim 1 wherein said plasma space etching precedes
said annealing.
3. The method of claim 1 wherein said annealing precedes said
plasma space etching.
4. CANCELLED
5. The method of claim 1 which includes, after said preparing
depositing a layer of oxide; smoothing the oxide by CMP, stopping
at the level of the polysilicon layer; depositing a bottom
electrode; depositing another layer of oxide by CVD; smoothing the
other layer of oxide by CMP, stopping said smoothing at the level
of the bottom electrode; depositing yet another layer of oxide by
CVD; and patterning and etching the oxide layers to form trench
structures.
6. The method of claim 1 wherein said plasma space etching of the
TiO.sub.x thin film includes setting TCP RF power at about 370W,
setting the bias power to about 130 W at a chamber pressure of
about 5 torr; and using etching including BCl.sub.3 at a flow rate
of about 30 sccm and Cl.sub.2 at a flow rate of about 58 sccm.
7. The method of claim 1 wherein said depositing a layer of
TiO.sub.x thin film, where 0<x<2, includes preparing a MOCVD
precursor, including dissolving about 0.2 mol
Ti(OC.sub.3H.sub.7).sub.4 in Octane, resulting in a precursor
solution having a concentration of 0.2 mol
Ti(OC.sub.3H.sub.7).sub.4.
8. The method of claim 7 which further includes injecting the
precursor solution into a CVD chamber vaporizer at temperature in
the range of between about 80.degree. C. to 120.degree. C. by a
liquid controller at a rate of between about 0.1 ml/min to 0.5
ml/min to form a precursor gases; maintaining a CVD chamber feed
line at a temperature of between about 80.degree. C. to 120.degree.
C.; maintaining the deposition temperature at between about
380.degree. C. to 420.degree. C.; maintaining the deposition
pressure at between about 0.5 torr to 5 torr, and continuing the
deposition process for between about five minutes to thirty
minutes.
9. A method of forming an H.sub.2 passivation layer in an FeRAM,
comprising: preparing a silicon substrate, depositing a layer of
TiO.sub.x thin film, where 0<x<2, on a damascene structure;
plasma space etching of the TiO.sub.x thin film to form a TiO.sub.x
sidewall, including setting TCP Rf power at about 370W, setting the
bias power to about 130 W at a chamber pressure of about 5 torr;
and using etching including BCl.sub.3 at a flow rate of about 30
sccm and Cl.sub.2 at a flow rate of about 58 sccm; annealing the
TiO.sub.x side wall thin film to form a TiO.sub.2 thin film;
depositing a layer of ferroelectric material; and metallizing to
form a FeRAM.
10. The method of claim 9 wherein said preparing a silicon
substrate includes doping to form a P-type silicon wafer, including
threshold adjustment ion implantation, shallow trench isolation
growth of a gate oxide, deposition of a polysilicon layer, ion
implantation to form an N.sup.+ source and an drain; smoothing the
oxide by CMP, and patterning and etching the polysilicon layer.
11. The method of claim 10 which includes, after said preparing,
depositing a layer of oxide; smoothing the oxide by CMP; stopping
at the level of the polysilicon layer; depositing a bottom
electrode; depositing another layer of oxide by CVD, smoothing the
other layer of oxide by CMP, stopping said smoothing at the level
of the bottom electrode; depositing ye another layer of oxide by
CVD; and patterning and etching of the oxide layers to form trench
structures.
12. CANCELLED
13. The method of claim 9 wherein said depositing a layer of
TiO.sub.x thin film, where 0<x<2, includes preparing a MOCVD
precursor, including dissolving about 0.2 mol
Ti(OC.sub.3H.sub.7).sub.4 in Octane, resulting in a precursor
solution having a concentration of 0.2 mol
Ti(OC.sub.3H.sub.7).sub.4.
14. The method of claim 13 which further includes injecting the
precursor solution into a CVD chamber vaporizer at temperature in
the range of between about 80.degree. C. to 120.degree. C. by a
liquid controller at a rate of between about 0.1 ml/min to 0.5
ml/min to form a precursor gases; maintaining a CVD chamber feed
line at a temperature of between about 80.degree. C. to 120.degree.
C.; maintaining the deposition temperature at between about
380.degree. C. to 420.degree. C.; maintaining the deposition
pressure at between about 0.5 torr to 5 torr, and continuing the
deposition process for between about five minutes to thirty
minutes.
15. A method of forming an H.sub.2 passivation layer in an FeRAM,
comprising: preparing a silicon substrate; depositing a layer of
TiO.sub.x thin film, where 0<x<2, on a damascene structure,
including preparing a MOCVD precursor, including dissolving about
0.2 mol Ti(OC.sub.3H.sub.7).sub.4 in Octane, resulting in a
precursor solution having a concentration of 0.2 mol
Ti(OC.sub.3H.sub.7).sub.4; annealing the TiO.sub.x side wall thin
film to form a TiO.sub.2 thin film; plasma space etching of the
TiO.sub.2 thin film to form a TiO.sub.2 sidewall; depositing a
layer of ferroelectric material; and metallizing to form a
FeRAM.
16. The method of claim 15 wherein said preparing a silicon
substrate includes doping to form a P-type silicon wafer, including
threshold adjustment ion implantation, shallow trench isolation,
growth of a gate oxide, deposition of a polysilicon layer, ion
implantation to form an N.sup.+ source and an drain; smoothing the
oxide by CMP, and patterning and etching the polysilicon layer.
17. The method of claim 16 which includes, after said preparing,
depositing a layer of oxide; smoothing the oxide by CMP, stopping
at the level of the polysilicon layer; depositing a bottom
electrode; depositing another layer of oxide by CVD, smoothing the
other layer of oxide by CMP, stopping said smoothing at the level
of the bottom electrode; depositing yet another layer of oxide by
CVD; and patterning and etching both of the oxide layers to form
trench structures.
18. The method of claim 15 wherein said plasma space etching of the
TiO.sub.x thin film includes setting TCP RF power at about 370W,
setting the bias power to about 130 W at a chamber pressure of
about 5 torr and using etching including BCl.sub.3 at a flow rate
of about 30 sccm and Cl.sub.2 at a flow rate of about 58 sccm.
19. CANCELLED
20. The method of claim 15 which further includes injecting the
precursor solution into a CVD chamber vaporizer at temperature in
the range of between about 80.degree. C. to 120.degree. C. by a
liquid controller at a rate of between about 0.1 ml/min to 0.5
ml/min to form a precursor gases; maintaining a CVD chamber feed
line at a temperature of between about 80.degree. C. to 120.degree.
C.; maintaining the deposition temperature at between about
380.degree. C. to 420.degree. C.; maintaining the deposition
pressure at between about 0.5 torr to 5 torr, and continuing the
deposition process for between about five minutes to thirty
minutes.
Description
FIELD OF THE INVENTION
[0001] This invention relates to oxide thin film processes for
H.sub.2 passivation layers, ferroelectric memory device structures
and integrated processes for ferroelectric non-volatile memory
devices, and specifically, to a method of depositing a TiO.sub.2
thin film which is used as an H.sub.2 passivation layer.
BACKGROUND OF THE INVENTION
[0002] Metal, Ferroelectrics, Insulator, and Silicon (MFMIS) and
Metal, Ferroelectrics, Insulator, and Silicon (MFIS) transistor
ferroelectric memory devices have been proposed for use as FeRAM
devices. In the integration processes of such devices, forming gas
annealing generally is necessary to reduce trapped charges in
high-k gate oxides and to improve the contact between metal
connections and the source and the drain. However, forming gas
annealing degrades the properties of ferroelectric thin films.
Therefore, a H.sub.2 passivation layer, covering the ferroelectric
thin film, is an important structure in fabrication of IT
ferroelectric memory devices.
SUMMARY OF THE INVENTION
[0003] A method of forming an H.sub.2 passivation layer in an FeRAM
includes preparing a silicon substrate; depositing a layer of
TiO.sub.x thin film, where 0<x<2, on a damascene structure;
plasma space etching of the TiO.sub.x thin film to form a TiO.sub.x
sidewall; annealing the TiO.sub.x side wall thin film to form a
TiO.sub.2 thin film; depositing a layer of ferroelectric material;
and metallizing the structure to form a FeRAM.
[0004] It is an object of the invention to provide a TiO.sub.2 thin
film as a H.sub.2 passivation layer for improving the properties of
1 T ferroelectric memory devices.
[0005] Another object of the invention is to provide a TiO.sub.x
thin film having good step coverage on a damascene structure.
[0006] A further object of the invention is to use a plasma space
etching process on a TiO.sub.x thin film to form a TiO.sub.2 thin
film as a H.sub.2 passivation layer.
[0007] This summary and objectives of the invention are provided to
enable quick comprehension of the nature of the invention. A more
thorough understanding of the invention may be obtained by
reference to the following detailed description of the preferred
embodiment of the invention in connection with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIGS. 1-8 depict steps in device formation according to the
method of the invention.
[0009] FIGS. 9 and 10 are microphotographs of the structure during
device fabrication.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] In the method of the invention, TiO.sub.x may be deposited
in either of two embodiments to make TiO.sub.2 as a H.sub.2
passivation layer. In the first embodiment of the method of the
invention, a CVD process is used to deposit Ti or TiO.sub.x thin
films on a damascene structure, providing good step coverage,
followed by plasma space etching of the TiO.sub.x thin film to form
a TiO.sub.x sidewall, and annealing the TiO.sub.x side wall thin
film to form a TiO.sub.2 thin film. The second embodiment of the
method of the invention includes a CVD process to deposit a
TiO.sub.x or TiO.sub.2 thin film on a damascene structure, again
providing good step coverage, annealing the TiO.sub.x thin film to
form a TiO.sub.2 thin film, and plasma space etching the TiO.sub.2
thin film to form a sidewall on the trench structure.
[0011] Referring initially to FIG. 1, a silicon wafer 10 is
prepared for fabrication of IC devices, which preparation may
include doping to form a P-type silicon wafer, including threshold
adjustment ion implantation, for use as a substrate for a Lead
Germanium Oxide (Pb.sub.5Ge.sub.3O.sub.- 11) (PGO) MFMPOS
one-transistor FeRAM device. FIG. 1 depicts the structure following
wafer preparation, STI and filling of the trenches so formed with
oxide 12, growth of a gate oxide 14 and deposition of a polysilicon
layer 16, and, in this example, ion implantation to form an N.sup.+
source 18 and an N.sup.+ drain 20. The oxide is smoothed by CMP,
photoresist is applied and the polysilicon layer etched.
[0012] FIG. 2 depicts the structure following CVD of oxide, which
is smoothed by CMP, stopping at the level of polysilicon layer 16.
A larger size bottom electrode 22, which, in the preferred
embodiment, is an Iridium electrode is deposited and patterned.
Another layer of oxide 24 is deposited by CVD and smoothed by CMP,
stopping at the level of the Iridium layer. tetraethylorthosilicate
oxide (oxane or TEOS) 26 is deposited by CVD, patterned and etched
to form trench structures.
[0013] FIG. 3 depicts the structure following CVD of a TiO.sub.x
layer 28, where 0<x<2. As will be apparent to those of skill
in the art, when x=0, the CVD is only of titanium. The MOCVD
process includes preparing a MOCVD precursor, including dissolving
0.2 mol Ti(OC.sub.3H.sub.7).sub.4 in Octane, resulting in a
precursor solution having a concentration of 0.2 mol
Ti(OC.sub.3H.sub.7).sub.4. The precursor solution is injected into
a vaporizer at temperature in the range of between about 80.degree.
C. to 120.degree. C. by a liquid controller at a rate of between
about 0.1 ml/min to 0.5 ml/min to form a precursor gases. The feed
line is maintained at between about 80.degree. C. to 120.degree.
C., the deposition temperature is between about 380.degree. C. to
420.degree. C., the deposition pressure is maintained at between
about 0.5 torr to 5 torr, and the deposition time ranges from
between about five minutes to thirty minutes, depending on the
required TiO.sub.2 thickness. TiO.sub.x layer 28 may be, in the
first embodiment of the method of the invention, plasma space
etched, then annealed in an oxygen atmosphere to form a TiO.sub.2
thin film. The structure is HF dipped to clean the surface of
Iridium bottom electrode 20, resulting in the structure depicted in
FIG. 4. The plasma space etching process for TiO.sub.x thin film 22
includes setting TCP Rf power at about 370 W and setting the bias
power to about 130 W at a chamber pressure of about 5 torr. The
etching chemicals used in the process include BCl.sub.3 at a flow
rate of about 30 sccm, and Cl.sub.2 at a flow rate of about 58
sccm.
[0014] FIG. 5 depicts the structure following selective deposition
of a ferroelectric thin film 24 by MOCVD. The upper surface of the
FE and TiO.sub.x extend above the level of the lastly deposited
oxide layer because PGO may be selectively deposited on iridium and
TiO.sub.2, but will not form on SiO.sub.2, therefor, the PGO will
only be deposited on those areas which have exposed iridium and
TiO.sub.2.
[0015] FIG. 6 depicts the structure following CMP of ferroelectric
thin film 30, surrounding TiO.sub.x 28, and oxide 26.
[0016] FIG. 7 depicts the structure following deposition and
annealing of a high-k oxide 32, deposition of a top electrode layer
34, and patterning and etching of the top electrode layer to form
top electrodes 34.
[0017] FIG. 8 depicts the FeRAM constructed according to the first
embodiment of the method of the invention following etching of
contact holes and metallization 36.
[0018] FIG. 9 depicts the structure following deposition of
TiO.sub.x thin film layer 28, which illustrates deposition on oxide
trench structures with very good step coverage.
[0019] FIG. 10 depicts the structure after plasma space etching,
and illustrates the TiO.sub.x side wall thin film formed on oxide
trench structures.
[0020] In the second embodiment of the method of the invention, the
same processes are followed, as described in connection with FIGS.
1-3. The annealing step, described in connection with FIG. 7, is
next performed, converting TiO.sub.x to TiO.sub.2, which is then
followed by the steps described in connection with FIGS. 4-6 and
8.
[0021] Thus, a method for MOCVD TiO.sub.2 thin film as FeRAM
H.sub.2 passivation layer has been disclosed. It will be
appreciated that further variations and modifications thereof may
be made within the scope of the invention as defined in the
appended claims.
* * * * *