U.S. patent application number 09/767523 was filed with the patent office on 2001-05-31 for methods of forming titanium nitride composite layers using composite gases having increasing tic14 to nh3 ratios.
Invention is credited to Chung, Ju-hyuck, Lee, Jang-eun, Seo, Tae-wook.
Application Number | 20010002334 09/767523 |
Document ID | / |
Family ID | 26633945 |
Filed Date | 2001-05-31 |
United States Patent
Application |
20010002334 |
Kind Code |
A1 |
Lee, Jang-eun ; et
al. |
May 31, 2001 |
Methods of forming titanium nitride composite layers using
composite gases having increasing TiC14 to NH3 ratios
Abstract
A method of forming a multilayer titanium nitride film hardly
containing any Cl component by a multiple step chemical vapor
deposition method, and a method of manufacturing a semiconductor
device using the same are provided. In the present invention, a
multilayer TiN film is formed by multiple step chemical vapor
deposition (CVD) on a semiconductor substrate on which an
underlayer is formed. In order to form the multilayer TiN film, an
underlayer protective TiN film is formed by forming a first TiN
film on the underlayer and NH.sub.3 annealing the first TiN film. A
main TiN film is formed by forming a second TiN film on the
underlayer protective TiN film and NH.sub.3 annealing the second
TiN film. A source gas used in order to form the first TiN film has
a smaller TiCl.sub.4 to NH.sub.3 gas flow ratio than a source gas
for forming the second TiN film. In order to apply the multilayer
TiN film to the fabrication of the semiconductor device, an
insulating film having a contact hole is formed on a semiconductor
substrate. A Ti film is formed on the inner wall of the contact
hole. A multilayer TiN film is formed on the Ti film by the
multiple step CVD method. A metal plug is formed on the multilayer
TiN film.
Inventors: |
Lee, Jang-eun; (Kyungki-do,
KR) ; Chung, Ju-hyuck; (Kyungki-do, KR) ; Seo,
Tae-wook; (Kyungki-do, KR) |
Correspondence
Address: |
MYERS BIGEL SIBLEY & SAJOVEC
PO BOX 37428
RALEIGH
NC
27627
US
|
Family ID: |
26633945 |
Appl. No.: |
09/767523 |
Filed: |
January 23, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
09767523 |
Jan 23, 2001 |
|
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09356928 |
Jul 19, 1999 |
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6207557 |
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Current U.S.
Class: |
438/652 ;
257/E21.17; 257/E21.584; 438/656; 438/660; 438/680; 438/685 |
Current CPC
Class: |
H01L 21/28556 20130101;
H01L 21/76843 20130101; H01L 21/76856 20130101; H01L 21/76846
20130101 |
Class at
Publication: |
438/652 ;
438/656; 438/660; 438/680; 438/685 |
International
Class: |
H01L 021/44 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 22, 1998 |
KR |
98-29527 |
Mar 18, 1999 |
KR |
99-9184 |
Claims
What is claimed is:
1. A method of forming a multilayer TiN film by a chemical vapor
deposition (CVD) method on a semiconductor substrate on which an
underlayer is formed, comprising the steps of: (a) forming an
underlayer protective TiN film on the underlayer; and (b) forming a
main TiN film on the underlayer protective TiN film.
2. The method of claim 1, wherein the underlayer is a Ti film.
3. The method of claim 2, wherein NH.sub.3 gas is pre-flown on the
surface of the Ti film before the step (a).
4. The method of claim 1, wherein the step (a) comprises the steps
of; (a-1) forming a first TiN film on the underlayer to have a
thickness of between 10 and 100 .ANG. using a source gas composed
of a mixture of TiCl.sub.4 gas and NH.sub.3 gas; and (a-2)
annealing the first TiN film in an NH.sub.3 gas atmosphere, and
wherein the step (b) comprises the steps of: (b-1) forming a second
TiN film on the underlayer protective TiN film using a source gas
formed of a mixture of TiCl.sub.4 gas and NH.sub.3 gas; and (b-2)
annealing the second TiN film in the NH.sub.3 gas atmosphere.
5. The method of claim 4, wherein the gas flow ratio of TiCl.sub.4
to NH.sub.3 is between 0.02 and 0.1 in the source gas.
6. The method of claim 4, wherein the first and second TiN films
are formed under a pressure of between 0.2 and 0.5 Torr and at a
temperature of between 530 and 680.degree.C.
7. The method of claim 4, wherein the steps of annealing the first
TiN film and the second TiN film are respectively performed at a
temperature of between 530 and 680.degree.C.
8. The method of claim 1, further comprising the step (c) of
forming an oxygen diffusion preventing TiN film on the main TiN
film after the step (b).
9. The method of claim 8, wherein the step (c) comprises the steps
of: (c-1) forming a third TiN film on the main TiN film using a
source gas composed of a mixture of TiCl.sub.4 gas and NH.sub.3
gas, to have a thickness of between 10 and 100 .ANG.; and (c-2)
annealing the third TiN film in the NH.sub.3 gas atmosphere.
10. The method of claim 9, wherein the gas flow ratio of TiCl.sub.4
to NH.sub.3 is between 0.02 and 0.1 in the source gas and the third
TiN film is formed under a pressure of between 0.2 and 0.5 Torr and
at a temperature of between 530 and 680.degree.C.
11. The method of claim 1, wherein the step (b) comprises the steps
of: (b-1) forming a TiN film on the underlayer protective TiN film
to have a thickness of between 10 and 100 .ANG. using a source gas
formed of a mixture of TiCl.sub.4 gas and NH.sub.3 gas; (b-2)
annealing the TiN film in an NH.sub.3 gas atmosphere; and (b-3)
repeating the steps (b-1) and (b-2) until the main TiN film having
a desired thickness is obtained.
12. The method of claim 11, wherein the gas flow ratio of
TiCl.sub.4 to NH.sub.3 is between 0.02 and 0.1 in the source gas
and the third TiN film is formed under a pressure of between 0.2
and 0.5 Torr and at a temperature of between 530 and
680.degree.C.
13. A method of forming a multilayer TiN film, comprising the steps
of: (a) forming a first TiN film covering an underlayer exposed on
a semiconductor substrate, by a chemical vapor deposition (CVD)
method using a source gas supplied in a first gas flow ratio having
a predetermined TiCl.sub.4 to NH.sub.3 gas flow ratio; (b)
annealing the first TiN film in an NH.sub.3 gas atmosphere to form
an underlayer protective TiN film; (c) forming a second TiN film on
the underlayer protective TiN film by the CVD method, using a
source gas supplied in a second gas flow ratio having a TiCl.sub.4
to NH.sub.3 gas flow ratio larger than the first gas flow ratio;
and (d) annealing the second TiN film in an NH.sub.3 gas atmosphere
to form a main TiN film.
14. The method of claim 13, wherein the first gas flow ratio and
the second gas flow ratio are selected to be between 0.02 and 0.1,
respectively.
15. The method of claim 14, wherein the first gas flow ratio is
selected to be between 0.02 and 0.05.
16. The method of claim 13, wherein the step of forming the first
TiN film and the step of forming the second TiN film are
respectively performed under a pressure of between 0.2 and 0.5 Torr
and at a temperature of between 530 and 680.degree. C.
17. The method of claim 13, wherein the steps of annealing the
first TiN film and the second TiN film are respectively performed
at a temperature of between 530 and 680.degree.C.
18. The method of claim 13, wherein the first TiN film has a
thickness of between 10 and 100 .ANG..
19. The method of claim 13, wherein the underlayer is a Ti
film.
20. The method of claim 13, after the step (d), further comprising
the steps of: (e) forming a third TiN film on the main TiN film
using a source gas supplied in a third gas flow ratio having a
TiCl.sub.4 to NH.sub.3 gas flow ratio which is smaller than the
second gas flow ratio; and (f) annealing the third TiN film in an
NH.sub.3 gas atmosphere.
21. The method of claim 20, wherein the third gas flow ratio is
selected to be between 0.02 and 0.1.
22. The method of claim 20, wherein the third TiN film has a
thickness of between 10 and 100 .ANG..
23. The method of claim 20, wherein the step of forming the third
TiN film is performed under a pressure of between 0.2 and 0.5 Torr
and at a temperature of between 530 and 680.degree.C.
24. The method of claim 20, wherein the step of annealing the third
TiN film is performed at a temperature of between 530 and
680.degree.C.
25. A method of forming a multilayer TiN film, comprising the steps
of: (a) forming a first TiN film covering an underlayer exposed on
a semiconductor substrate by the CVD method, using a source gas
supplied in a first gas flow ratio having a predetermined
TiCl.sub.4 to NH.sub.3 gas flow ratio; (b) forming a second TiN
film on the first TiN film by the CVD method, using a source gas
supplied in a second gas flow ratio having a TiCl.sub.4 to NH.sub.3
gas flow ratio which is larger than the first gas flow ratio; and a
(c) annealing the first TiN film and the second TiN film in a
NH.sub.3 gas atmosphere.
26. The method of claim 25, wherein the underlayer is a Ti
film.
27. The method of claim 25, wherein the first gas flow ratio and
the second gas flow ratio are selected to be between 0.02 and 0.1,
respectively.
28. The method of claim 25, wherein the first gas flow ratio is
selected to be between 0.02 and 0.05.
29. The method of claim 25, wherein the step of forming the first
TiN film and the step of forming the second TiN film are
respectively performed under a pressure of between 0.2 and 0.5 Torr
and at a temperature of between 530 and 680.degree.C.
30. The method of claim 25, wherein the annealing step is performed
at a temperature of between 530 and 680.degree.C.
31. The method of claim 25, wherein the first TiN film has a
thickness of between 10 and 100 .ANG..
32. A method of manufacturing a semiconductor substrate, comprising
the steps of: (a) forming an insulating film having a contact hole
on a semiconductor substrate; (b) forming a Ti film on the inner
wall of the contact hole; (c) forming a multilayer TiN film by
repeating a process of forming a TiN film on the Ti film by a CVD
method using a source gas composed of a mixture of TiCl.sub.4 gas
and NH.sub.3 gas and annealing the TiN film in an NH.sub.3 gas
atmosphere at least two times; and (d) forming a metal plug on the
multilayer TiN film.
33. The method of claim 32, wherein, in the step (c), the step of
forming the multilayer TiN film comprises the steps of: forming a
Ti protecting TiN film using a source gas supplied in a first gas
flow ratio having a predetermined TiCl.sub.4 to NH.sub.3 gas flow
ratio; and forming a main TiN film using a source gas supplied in a
second gas flow ratio having a TiCl.sub.4 to NH.sub.3 gas flow
ratio which is larger than the first gas flow ratio.
34. The method of claim 33, wherein the step of forming the Ti
protecting TiN film comprises the steps of: forming a first TiN
film on the Ti film, to have a thickness of between 10 and 100
.ANG., using a source gas supplied in the first gas flow ratio
selected to be between 0.02 and 0.05; and annealing the first TiN
film in an NH.sub.3 gas atmosphere, and the step of forming the
main TiN film comprises the steps of: forming a second TiN film on
the Ti protecting TiN film using a source gas supplied in the
second gas flow ratio selected to be between 0.02 and 0.1; and
annealing the second TiN film in an NH.sub.3 gas atmosphere.
35. The method of claim 33, wherein the step of forming the
multilayer TiN film further comprises the step of forming an oxygen
diffusion preventing TiN film on the main TiN film.
36. The method of claim 35, wherein the step of forming the oxygen
diffusion preventing TiN film comprises the steps of: forming a
third TiN film on the main Ti film using the source gas, to have a
thickness of between 10 and 100 .ANG.; and annealing the third TiN
film in an NH.sub.3 gas atmosphere.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method of manufacturing a
semiconductor device, and more particularly, to a method of forming
a titanium nitride film and a method of manufacturing a
semiconductor device using the same.
[0003] 2. Description of the Related Art
[0004] An adhesive layer having a Ti/TiN structure is generally
employed in order to improve the poor adhesive characteristic of a
metal such as tungsten (W) for filling a contact hole, when a metal
contact plug required for the metal wiring of a semiconductor
device is formed.
[0005] In a conventional technology, a physical vapor deposition
(PVD) method such as a sputtering method is used for forming the
adhesive layer having the Ti/TiN structure. However, when the
Ti/TiN structure is formed by the PVD method, a film having a poor
step coverage is obtained. Therefore, in the case of forming a
contact having a large aspect ratio, the overhang of the Ti/TiN
film is severe at the entrance of the contact hole when the Ti/TiN
film is used as the adhesive layer or a barrier layer. Accordingly,
a large void is formed in the contact during a subsequent process
of depositing a tungsten film. Also, when the Ti/TiN film is too
thin on the bottom of the contact due to the poor step coverage of
the Ti/TiN film, WF.sub.6 gas, used as a source gas during a
subsequent process of depositing the tungsten film, and Ti of the
Ti/TiN film react, thus forming a nonconductor or vaporizing some
part. Accordingly, the TiN film is lifted and peeled off. If so,
the Ti/TiN film cannot serve as a barrier with respect to the
WF.sub.6 gas.
[0006] Therefore, a process of forming a TiN film by a chemical
vapor deposition (CVD) method has been recently developed.
[0007] In particular, the TiN film formed by the CVD method using
TiCl.sub.4 gas as a source gas is generally used as an adhesive
layer of a metal film or a barrier film when a metal contact or a
capacitor is formed since it is possible to obtain a good step
coverage.
[0008] A large amount of chlorine (Cl) is included in the formed
TiN film in the method of forming the TiN film by the CVD method
using the TiCl.sub.4 gas as the source gas. The TiN film containing
a large amount of Cl shows a high resistivity. Also, since Cl
permeates and damages the Ti film which is an underlayer, a high
temperature rapid thermal nitration (RTN) process, or an NH.sub.3
plasma process is required on the Ti film in order to prevent the
Cl permeation.
[0009] When the high temperature RTN process or the NH.sub.3 plasma
process is performed with respect to the Ti film, the following
problems occur. Firstly, the number of processes increases and a
semiconductor manufacturing process becomes complicated since the
above process is added. Secondly, additional equipment should be
introduced since the above process is added. As a result, the
burden of equipment investment increases. Thirdly, shallow
junctions have recently started to be realized in semiconductor
devices. Therefore, the allowed thickness of the Ti film deposited
as the barrier film in the contact hole is restricted. However, a
considerable amount of Ti is consumed in the Ti film by the high
temperature RTN process or the NH.sub.3 plasma process. As a result
it is not possible to secure a stable contact resistance since the
amount of residing Ti becomes small.
SUMMARY OF THE INVENTION
[0010] To solve the above problem(s), it is an objective of the
present invention to provide a method of forming a multilayer TiN
film so as to lower the amount of Cl in a TiN film introduced when
the TiN film is formed by a chemical vapor deposition (CVD) method
such that the device does not deteriorate.
[0011] It is another objective of the present invention to provide
a method of manufacturing a multilayer TiN film by which it is
possible to simplify a process by reducing the number of process
steps.
[0012] It is still another objective of the present invention to
provide a method for manufacturing a semiconductor device using the
TiN film formed by the above method.
[0013] Accordingly, to achieve the first and second objectives,
there is provided a method of forming a multilayer TiN film by a
chemical vapor deposition (CVD) method on a semiconductor substrate
on which an underlayer is formed. In this method, an underlayer
protective TiN film is formed on the underlayer. A main TiN film is
formed on the underlayer protective TiN film.
[0014] The underlayer is a Ti film. At this time, NH.sub.3 gas may
be pre-flown on the surface of the Ti film before the step (a).
[0015] The step (a) comprises the steps of (a-1) forming a first
TiN film on the underlayer to have a thickness of between 10 and
100 .ANG. using a source gas composed of a mixture of TiCl.sub.4
gas and NH.sub.3 gas and (a-2) annealing the first TiN film in an
NH.sub.3 gas atmosphere.
[0016] The step (b) comprises the steps of (b-1) forming a second
TiN film on the underlayer protective TiN film using a source gas
formed of a mixture of TiCl.sub.4 gas and NH.sub.3 gas and (b-2)
annealing the second TiN film in the NH.sub.3 gas atmosphere.
[0017] The gas flow ratio of TiCl.sub.4 to NH.sub.3 is between 0.02
and 0.1 in the source gas.
[0018] The first and second TiN films are formed under a pressure
of between 0.2 and 0.5 Torr and at a temperature of between 530 and
680.degree.C.
[0019] The steps of annealing the first TiN film and the second TiN
film are respectively performed at a temperature of between 530 and
680.degree. C.
[0020] The step (c) of forming an oxygen diffusion preventing TiN
film on the main TiN film can be further comprised after the step
(b).
[0021] The step (c) comprises the steps of (c-1) forming a third
TiN film on the main TiN film using a source gas composed of a
mixture of TiCl.sub.4 gas and NH.sub.3 gas, to have a thickness of
between 10 and 100 .ANG. and (c-2) annealing the third TiN film in
the NH.sub.3 gas atmosphere.
[0022] The third TiN film is formed under a pressure of between 0.2
and 0.5 Torr and at a temperature of between 530 and 680.degree.
C.
[0023] In order to form the main TiN film, a TiN film is formed on
the underlayer protective TiN film to have a thickness of between
10 and 100 .ANG. using a source formed of a mixture of TiCl.sub.4
gas and NH.sub.3 gas. The TiN film is annealed in an NH.sub.3 gas
atmosphere. The above steps are repeated until the main TiN film
having a desired thickness is obtained.
[0024] Also, to achieve the above objectives, a first TiN film
covering the underlayer exposed on a semiconductor substrate is
formed by a chemical vapor deposition (CVD) method using a source
gas supplied in a first gas flow ratio having a predetermined
TiCl.sub.4 to NH.sub.3 gas flow ratio. The first TiN film is
annealed in an NH.sub.3 gas atmosphere to form an underlayer
protective TiN film. A second TiN film is formed on the underlayer
protective TiN film by the CVD method, using a source gas supplied
in a second gas flow ratio having a TiCl.sub.4 to NH.sub.3 gas flow
ratio larger than the first gas flow ratio. The second TiN film is
annealed in an NH.sub.3 gas atmosphere to form a main TiN film.
[0025] The first gas flow ratio and the second gas flow ratio are
selected to be between 0.02 and 0.1, respectively. The first gas
flow ratio is selected to be between 0.02 and 0.05.
[0026] The step of forming the first TiN film and the step of
forming the second TiN film are respectively performed under a
pressure of between 0.2 and 0.5 Torr and at a temperature of
between 530 and 680.degree.C.
[0027] The steps of annealing the first TiN film and the second TiN
film are respectively performed at a temperature of between 530 and
680.degree.C.
[0028] After forming the main TiN film, a third TiN film is formed
on the main TiN film using a source gas supplied in a third gas
flow ratio having a TiCl.sub.4 to NH.sub.3 gas flow ratio which is
smaller than the second gas flow ratio. The third TiN film is
annealed in an NH.sub.3 gas atmosphere.
[0029] The third gas flow ratio is selected to be between 0.02 and
0.1.
[0030] Also, to achieve the above objectives, in the present
invention, a first TiN film covering the underlayer exposed on a
semiconductor substrate by the CVD method, using a source gas
supplied in a first gas flow ratio having a predetermined
TiCl.sub.4 to NH.sub.3 gas flow ratio. A second TiN film is formed
on the first TiN film by the CVD method, using a source gas
supplied in a second gas flow ratio having a TiCl.sub.4 to NH.sub.3
gas flow ratio which is larger than the first gas flow ratio. The
first TiN film and the second TiN film are annealed in a NH.sub.3
gas atmosphere.
[0031] To achieve the third objective, in a method of manufacturing
a semiconductor substrate according to the present invention, an
insulating film having a contact hole is formed on a semiconductor
substrate. A Ti film is formed on the inner wall of the contact
hole. A multilayer TiN film is formed by repeating a process of
forming a TiN film on the Ti film by a CVD method using a source
gas composed of a mixture of TiCl.sub.4 gas and NH.sub.3 gas and
annealing the TiN film in an NH.sub.3 gas atmosphere at least two
times. A metal plug is formed on the multilayer TiN film.
[0032] According to the present invention, it is possible to obtain
a densified multilayer TiN film sufficiently removed of the Cl
component so that the device is not deteriorated. When the
multilayer TiN film according to the present invention is used as a
barrier film of a metal contact, it is possible to reduce the
resistance of the contact and to omit an additional process such as
a high temperature rapid thermal nitration (RTN) process for
protecting an underlayer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The above objectives and advantages of the present invention
will become more apparent by describing in detail a preferred
embodiment thereof with reference to the attached drawings in
which:
[0034] FIGS. 1A through 1F are cross sectional views for describing
a method of forming a multilayer TiN film according to a first
embodiment of the present invention;
[0035] FIGS. 2A and 2B are cross sectional views for describing a
method of forming a multilayer TiN film according to a second
embodiment of the present invention;
[0036] FIGS. 3A through 3F are cross sectional views for describing
a method of forming a multilayer TiN film according to a third
embodiment of the present invention;
[0037] FIGS. 4A through 4C are cross sectional views for describing
a method of forming a multilayer TiN film according to a fourth
embodiment of the present invention;
[0038] FIG. 5 is a graph showing the resistivities of a multilayer
TiN film formed according to the present invention and TiN films
formed by a conventional method; and
[0039] FIGS. 6A through 6E are cross sectional views for describing
a method of manufacturing a semiconductor device according to a
preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] Hereinafter, preferred embodiments of the present invention
will be described in detail with reference to the attached
drawings.
[0041] FIGS. 1A through 1F are cross sectional views showing
processes of a method of forming a multilayer TiN film by a
multiple step chemical vapor deposition (CVD) process according to
a first embodiment of the present invention.
[0042] Referring to FIG. 1A, an underlayer 10 such as a Ti film is
formed on a semiconductor substrate (not shown). The underlayer 10
may be TaO or Pt. A first TiN film 22 is formed on the underlayer
10 by a chemical vapor deposition (CVD) method using a mixture of
TiCl.sub.4 gas and NH.sub.3 gas as a source gas, to have a
thickness of between 10 and 100 .ANG. in the first step of forming
a multilayer TiN film by a multiple step deposition. The deposition
process is performed at a temperature of between 530 and
680.degree. C. Here, the first TiN film 22 is formed on the
underlayer 10 through thermal reduction of the TiCl.sub.4 gas with
the NH.sub.3 gas in the source gas.
[0043] At this time, the flow rates of the TiCl.sub.4 gas and the
NH.sub.3 gas, each of which compose the source gas, are controlled
so as to obtain a TiCl.sub.4 to NH.sub.3 gas flow ratio of between
0.02 and 0.1. The reaction pressure during the formation of the
first TiN film 22 is between 0.2 and 0.5 Torr.
[0044] Preferably, an NH.sub.3 pre-flow step of providing the
NH.sub.3 gas on the surface of the underlayer 10 may be performed
before forming the first TiN film 22. The NH.sub.3 pre-flow step is
performed for 60 seconds at a temperature of between 530 and
680.degree.C. and under a pressure of 0.3 Torr.
[0045] Referring to FIG. 1B, the first TiN film 22 is annealed in
an NH.sub.3 gas atmosphere. For this, the NH.sub.3 gas is provided
on the first TiN film 22 at the temperature of between 530 and
680.degree.C. As a result, a Cl component existing on the surface
or the grain boundary of the first TiN film 22 is completely
removed and the place from which Cl is removed is filled with an N
component. Accordingly, the first TiN film 22 is densified.
Therefore, an underlayer protective TiN film 22a which contains few
Cl component is formed. Also, there are few Cl components in the
interface between the underlayer protective TiN film 22a and the
underlayer 10. For example, the NH.sub.3 gas of 1,000 sccm is
supplied for 60 seconds under a pressure of 3 Torr and at the
temperature of between 530 and 680.degree. C., for the NH.sub.3
annealing.
[0046] The underlayer protective TiN film 22a obtained after the
NH.sub.3 annealing is sufficiently removed of the Cl component and
the place from which Cl is removed is filled with the N component.
Accordingly, the underlayer protective TiN film 22a is densified.
Therefore, it is difficult for the Cl component to permeate the
underlayer protective TiN film 22a from the TiCl.sub.4 gas when a
TiN film is formed using the TiCl.sub.4 gas in a subsequent
process. Therefore, it is possible to prevent the underlayer 10
from being damaged by the Cl component.
[0047] Referring to FIG. 1C, a second TiN film 24 is formed on the
underlayer protective TiN film 22a to a predetermined thickness.
The thickness of the second TiN film 24 is determined considering
the thicknesses of the underlayer protective TiN film 22a according
to the total thickness of the multilayer TiN film to be formed. The
deposition conditions at this time are the same as those of forming
the first TiN film 22 described with reference to FIG. 1A.
[0048] Referring to FIG. 1D, a main TiN film 24a removed of the Cl
component contained in the second TiN film 24 and having a
densified structure is formed by annealing the second TiN film 24
in the NH.sub.3 gas atmosphere by the same method as that described
with reference to FIG. 1B.
[0049] It is possible to prevent the Cl component from permeating
into the underlayers of the main TiN film 24a during the subsequent
process of depositing a TiN film on the main TiN film 24a using the
TiCl.sub.4 gas since the main TiN film 24a removed of the Cl
component has a densified structure.
[0050] Referring to FIG. 1E, a third TiN film 26 is formed on the
main TiN film 24a by the same method as that of forming the first
TiN film 22 described with reference to FIG. 1A, to have the
thickness of between 10 and 100 .ANG..
[0051] Referring to FIG. 1F, the Cl component is removed from the
third TiN film 26 by annealing the third TiN film 26 in a NH.sub.3
gas atmosphere, and a densified oxygen diffusion preventing TiN
film 26a is formed by the same method as that described with
reference to FIG. 1B.
[0052] The multilayer TiN film 20 formed of the underlayer
protective TiN film 22a, the main TiN film 24a, and the oxygen
diffusion preventing TiN film 26a is formed on the underlayer 10 by
a multiple step CVD method.
[0053] As mentioned above, when the semiconductor substrate on
which the multilayer TiN film 20 is formed is exposed to the air
for a subsequent process after forming the multilayer TiN film 20
by the CVD method, it is possible to prevent oxygen in the air from
permeating the multilayer TiN film 20 by the oxygen diffusion
preventing TiN film 26a formed on the surface of the multilayer TiN
film 20. Therefore, it is possible to prevent the resistivity from
increasing due to the permeation of oxygen into the multilayer TiN
film 20 including the oxygen diffusion preventing TiN film 26a
formed by the multiple step CVD method.
[0054] In the above embodiment, the multilayer TiN film is formed
by a three step deposition process. However, the present invention
is not restricted to this.
[0055] For example, if the increase of the resistivity according to
the permeation of oxygen is negligible, thus not deteriorating the
device, the process of forming the oxygen diffusion preventing TiN
film 26a can be omitted in order to simplify processes and to save
expenses.
[0056] Also, it is possible to form a multilayer TiN film comprised
of three or more layers by a multiple step CVD method as follows,
instead of forming the multilayer TiN film by the three step
deposition process as mentioned in the above embodiment.
[0057] FIGS. 2A and 2B are cross sectional views showing processes
of the method of forming the multilayer TiN film by the multiple
step CVD process according to a second embodiment of the present
invention.
[0058] Referring to FIG. 2A, after forming an underlayer 50 on a
semiconductor substrate (not shown) by the same method as that
described with reference to FIG. 1A, an underlayer protective TiN
film 62a is formed on the underlayer 50 to have a thickness of
between 10 and 100 .ANG.. A second TiN film 64 is formed on the
underlayer protective TiN film 62a by the same method as the method
of forming the first TiN film 22 described with reference to FIG.
1A, to have a thickness of between 10 and 100 .ANG..
[0059] Referring to FIG. 2B, the Cl component contained in the
second TiN film 64 is completely removed by annealing the second
TiN film 64 in an NH.sub.3 gas atmosphere by the same method as
that describe with reference to FIG. 1B.
[0060] Accordingly, a densified first main TiN film 64a is
formed.
[0061] Then, a plurality of main TiN films are formed to have a
desired thickness by sequentially forming a second main TiN film
(not shown), a third main TiN film (not shown), . . . on the first
main TiN film 64a by repeating the step of forming the TiN film of
FIG. 2A and the NH.sub.3 annealing step of FIG. 2B as many times as
required with respect to the resultant material in which the first
main TiN film 64a is formed.
[0062] The method according to the second embodiment, described
with reference to FIGS. 2A and 2B, may require a longer process
time than the method according to the first embodiment, described
in FIGS. 1A through IF. However, the TiN film obtained by the
method according to the second embodiment contains less Cl
component and is more dense.
[0063] FIGS. 3A through 3F are cross sectional views showing
processes of the method of forming a multilayer TiN film by the
multiple step CVD process according to a third embodiment of the
present invention.
[0064] Referring to FIG. 3A, an underlayer 70 such as a Ti film is
formed on the semiconductor substrate (not shown). A first TiN film
72 is formed on the underlayer 70, to a thickness of between 10 and
100 .ANG., by the CVD method under a pressure of between 0.2 and
0.5 Torr and at a temperature of between 530 and 680.degree.C.,
using a source gas composed of a mixture of the TiCl.sub.4 gas and
the NH.sub.3 gas supplied in a first gas flow ratio of TiCl.sub.4
to NH.sub.3 selected from a value between 0.02 and 0.1 and having a
relatively low Cl content. Preferably, the first gas flow ratio is
selected from a value between 0.02 and 0.05, more preferably, from
a value between 0.03 and 0.04.
[0065] Referring to FIG. 3B, the first TiN film 72 is annealed in
an NH.sub.3 atmosphere at a temperature of between 530 and
680.degree.C. As a result, the Cl component existing on the surface
of the first TiN film 72 or the grain boundary in the first TiN
film 72 is completely removed and the place from which Cl is
removed is filled with an N component. Accordingly, the first TiN
film 72 is densified. Therefore, an underlayer protective TiN film
72a which contains a small amount of the Cl component is formed on
the underlayer 70. Also, there is a small amount of the Cl
component in the interface between the underlayer protective TiN
film 72a and the underlayer 70. For example, the NH.sub.3 gas of
1,000 sccm is supplied for 60 seconds under the pressure of 3 Torr
and at the temperature of between 530 and 680.degree. C., for the
NH.sub.3 annealing.
[0066] Since the underlayer protective TiN film 72a is obtained by
depositing the first TiN film 72 using a source gas containing a
relatively low content of Cl and by sufficiently removing the Cl
component residing in the TiN film 72, it is possible to contact
the underlayer protective TiN film 72a, completely removed of the
Cl component, to the underlayer 70. Also, in the underlayer
protective TiN film 72a, the place from which Cl is removed is
filled with an N component by the NH.sub.3 annealing. Accordingly
the underlayer protective TiN film 72a is densified. Therefore, it
is difficult for the Cl component to permeate the underlayer
protective TiN film 72a from the TiCl.sub.4 gas when a TiN film is
formed, using the TiCl.sub.4 gas in a subsequent process, on the
underlayer protective TiN film 72a. Therefore, it is possible to
prevent the underlayer 70 from being damaged by the Cl
component.
[0067] Referring to FIG. 3C, a second TiN film 74 is formed on the
underlayer protective TiN film 72a to have a predetermined
thickness, by the CVD method, using a source gas supplied in a
second gas flow ratio of TiCl.sub.4 to NH.sub.3 selected from a
value between 0.02 and 0.1 and larger than the first gas flow
ratio, so as to have a larger content of Cl than in the source gas
supplied in the first gas flow ratio. The thickness of the second
TiN film 74 is determined considering the thicknesses of the
underlayer protective TiN film 72a according to the total thickness
of the multilayer TiN film to be formed. The deposition temperature
and the pressure condition at this time are the same as those of
forming the first TiN film 72 described with reference to FIG.
3A.
[0068] Referring to FIG. 3D, the second TiN film 74 is annealed in
the NH.sub.3 atmosphere and the Cl component contained in the
second TiN film 74 is removed by the same method as that described
with reference to FIG. 3B. Accordingly, a densified main TiN film
74a is formed.
[0069] Referring to FIG. 3E, a third TiN film 76 is formed on the
main TiN film 74a to have a thickness of between 10 and 100 .ANG.
by the same method as the method of forming the first TiN film 72
described with reference to FIG. 3A. A source gas supplied in a
third flow ratio of TiCl.sub.4 to NH.sub.3 selected from a value
between 0.02 and 0.1 and smaller than the second gas flow ratio so
as to contain a smaller content of Cl than in the source gas
supplied in the second gas flow ratio.
[0070] Referring to FIG. 3F, a densified oxygen diffusion
preventing TiN film 76a is formed by annealing the third TiN film
76 in the NH.sub.3 gas atmosphere and removing the Cl component
from the third TiN film 76 by the same method as that described
with reference to FIG. 3B.
[0071] A multilayer TiN film 78 comprised of the underlayer
protective TiN film 72a, the main TiN film 74a, and the oxygen
diffusion preventing TiN film 76a is formed on the underlayer 70 by
the multiple step CVD method.
[0072] The step of forming the oxygen diffusion preventing TiN film
76a described with reference to FIGS. 3E and 3F can be omitted if
necessary.
[0073] It is possible to prevent oxygen in the air from permeating
the multilayer TiN film 78, since the multilayer TiN film 78 has a
densified structure, when the semiconductor substrate on which the
multilayer TiN film 78 is formed is exposed to air in order to
perform a subsequent process. Therefore, it is possible to prevent
the resistivity from increasing due to the permeation of oxygen in
the multilayer TiN film 78 formed by the multiple step CVD
method.
[0074] FIGS. 4A through 4C are cross sectional views showing
processes of the method of forming a multilayer TiN film by the
multiple step CVD method according to a fourth embodiment of the
present invention.
[0075] Referring to FIG. 4A, an underlayer 80, for example, a Ti
film is formed on a semiconductor substrate (not shown). A first
TiN film 82 is formed on the underlayer 80 to have a thickness of
between 10 and 100 .ANG. by the CVD method under a pressure of
between 0.2 and 0.5 Torr and at a temperature of between 530 and
680.degree. C., using a source gas composed of a mixture of the
TiCl.sub.4 gas and the NH.sub.3 gas supplied in a first gas flow
ratio of TiCl.sub.4 to NH.sub.3 selected from a value between 0.02
and 0.1 and having a relatively low Cl component. Preferably, the
first gas flow ratio is selected between 0.02 and 0.05, more
preferably, from a value between 0.03 and 0.04.
[0076] Referring to 4B, a second TiN film 84 is formed on the first
TiN film 82 by the CVD method, to have a predetermined thickness,
using a source gas supplied in a second gas flow ratio of
TiCl.sub.4 to NH.sub.3 selected between 0.02 and 0.1 and larger
than the first gas flow ratio so as to have a larger content of Cl
than in the source gas supplied in the first gas flow ratio. The
thickness of the second TiN film 84 is determined considering the
thicknesses of the first TiN film 82 according to the total
thickness of the multilayer TiN film to be formed. The deposition
temperature and the pressure condition at this time are the same as
those of forming the first TiN film 82 described with reference to
FIG. 4A.
[0077] Referring to 4C, the resultant obtained by sequentially
stacking the first TiN film 82 and the second TiN film 84 is
annealed in a NH.sub.3 gas atmosphere at a temperature of 530 to
680.degree.C. For the NH.sub.3 annealing, 1000 sccm of the NH.sub.3
gas is supplied for 60 seconds under a pressure of 3 Torr and at
the temperature of between 530 and 680.degree. C. As a result, the
Cl component existing on the surfaces or the grain boundaries of
the first and second TiN films 82 and 84 is completely removed and
the place from which Cl is removed is filled with the N component,
thus obtaining a multilayer TiN film 88 comprised of the densified
underlayer protective TiN film 82a and main TiN film 84a.
[0078] In the present embodiment, the step of NH.sub.3 annealing
the first TiN film 82 was omitted before forming the second TiN
film 84. However, the structure of the multilayer TiN film 88 in
which the surface and inside thereof is completely removed of the
Cl component by the above method is densified. Therefore, although
the multilayer TiN film 88 is exposed to air, it is possible to
prevent oxygen from permeating the multilayer TiN film 88.
Therefore, it is possible to prevent the resistivity from
increasing due to the permeation of oxygen into the multilayer TiN
film 88.
[0079] FIG. 5 is a graph showing the result of comparing the
resistivity of the multilayer TiN film formed by the multiple step
CVD method according to the present invention with the resistivity
of the TiN film formed by the conventional method.
[0080] In FIG. 5, (a) shows a case of a multilayer TiN film formed
by a multilayer deposition method according to the present
invention. To be specific, a multilayer TiN film having a thickness
of 500 .ANG. is formed by successively repeating the process of
NH.sub.3 annealing the TiN film obtained after forming the TiN film
having a thickness of 50 .ANG. by the CVD method 10 times. The
characteristics denoted by (b) and (c) show cases in which the TiN
film having the thickness of 500 .ANG. is deposited in one step by
the CVD method and the NH.sub.3 gas is supplied to the TiN film. To
be specific, (b) shows a case in which 1,000 sccm of NH.sub.3 gas
is supplied at a temperature of 680.degree. C. and under a
relatively high pressure of 3 Torr. (c) shows a case in which 400
sccm of the NH.sub.3 gas is supplied at a temperature of
680.degree.C. and under a relatively low pressure of 0.3 Torr. The
characteristic denoted by (d) shows a case in which a TiN film
having a thickness of 500 .ANG. is deposited in one step by the CVD
method, in which the step of providing the NH.sub.3 gas is
omitted.
[0081] It is noted from the result of FIG. 5 that the multilayer
TiN film formed by the multiple step deposition method according to
the present invention has much lower resistivity than the
conventional methods.
[0082] As a result, it is noted that the multilayer TiN film formed
by the multiple step CVD method according to the present invention
contains an extremely small content of Cl and hardly undergoes
increment of the resistivity due to substitution of oxygen when the
multilayer TiN film is exposed to air.
[0083] Also, the Ti film is not damaged at all by the Cl component
during the formation of the TiN film and the lifting of the TiN
film is prevented by forming the multilayer TiN film on the Ti film
by the multiple step CVD method according to the present invention
without performing the RTN process or the NH.sub.3 plasma process
after forming the Ti film. As a result, it is possible to form a
TiN film having low resistivity by forming the TiN film to have a
small amount of Cl by the multiple step CVD method.
[0084] Therefore, it is possible to reduce contact resistance when
the multilayer TiN film formed by the above method is employed as a
barrier film in a metal contact.
[0085] FIGS. 6A through 6E are cross sectional views showing
processes of a method of manufacturing a semiconductor device
according to a preferred embodiment of the present invention.
[0086] Referring to FIG. 6A, an interlayer dielectric film 110
having a contact hole for exposing a part of a conductive layer
(not shown), which is formed on a semiconductor substrate 100.
[0087] Referring to FIG. 6B, a Ti film 120 is formed on the
resultant in which the contact hole H is formed by a sputtering
method or the CVD method to have a thickness of about between 300
and 900 .ANG..
[0088] Referring to FIG. 6C, a multilayer TiN film 130 is formed on
the Ti film 120 using a source gas comprised of TiCl.sub.4 gas and
NH.sub.3 gas.
[0089] The multilayer TiN film 130 is obtained by forming a Ti film
protective TiN film 132, a main TiN film 134, and an oxygen
diffusion preventing TiN film 136 by the same method as that of the
first embodiment. The main TiN film 134 can be formed of a single
film formed by the single step CVD process. However, it may be
formed of a multilayer film formed by the multiple step CVD
process.
[0090] When the main TiN film 134 is formed of a multilayer film,
the main TiN film is 134 having a desired thickness is formed by
repeating, as many times as required, the step of forming a TiN
film on the Ti protecting TiN film 132, by the CVD method to have a
thickness of between 10 and 100 .ANG. and the step of NH.sub.3
annealing the TiN film, thus removing the Cl component in the TiN
film and densifying the TiN film.
[0091] In the present embodiment, the multilayer TiN film 130 is
described to be comprised of the Ti protecting TiN film 132, the
main TiN film 134, and the oxygen diffusion preventing TiN film
136. However, the present invention is not restricted to this.
[0092] For example, the oxygen diffusion preventing TiN film 136
can be omitted in order to simplify the process and to save
expenses when the increase of resistivity according to the
permeation of oxygen is negligible, thus not deteriorating the
device.
[0093] Referring to FIG. 6D, a metal layer 140 is formed by
depositing a metal such as tungsten on the resultant in which the
multilayer TiN film 130 is formed so as to fill the inside of the
contact hole H.
[0094] Referring to FIG. 6E, the upper surface of the interlayer
dielectric film 110 is exposed by polishing the resultant in which
the metal layer 140 is formed by a chemical mechanical polishing
method, and a barrier film comprised of the Ti film 120 and the
multilayer TiN film 130 and a metal plug 140a on the barrier film
are formed in the contact hole H.
[0095] As mentioned above, when the multilayer TiN film formed by a
multiple step CVD method is used as a TiN film constructing the
barrier film of the Ti/TiN structure in order to form the contact
of a semiconductor device, it is possible to prevent the Ti film
from being damaged, to prevent the TiN film from being lifted by
the multilayer TiN film which does not contain the Cl component,
and to remarkably lower resistivity in the TiN film, without
performing a subsequent process such as the RTN process after
forming the Ti film.
[0096] In the method for manufacturing a semiconductor device
according to the present embodiment, only the case in which the
method of forming the multilayer TiN film according to the first
embodiment is described. However, the present invention is not
restricted to this. The multilayer TiN film formed by all methods
provided in the detailed description of the present invention, and
methods which can be varied within the scope of the present
invention by anyone skilled in the art, can be applied to the
process of forming the contact of the semiconductor device.
[0097] As mentioned above, when the multilayer TiN film is formed
by the multiple step CVD method according to the present invention,
it is possible to completely remove the Cl component in the TiN
film and to make the TiN film dense. Therefore, it is possible to
prevent the Cl component of the source gas TiCl.sub.4 from
permeating into the Ti film which is the underlayer of the TiN
film, during the process of depositing the TiN film on the Ti film.
Accordingly, it is possible to prevent the underlayer from being
damaged by the Cl component and to prevent the TiN film formed on
the underlayer from being lifted.
[0098] Also, since the multilayer TiN film formed by the multiple
step deposition method according to the present invention does not
contain the Cl component and is dense, the resistivity in the TiN
film is remarkably low. Therefore, when the multilayer TiN film
formed by the method according to the present invention is used as
the barrier film of a contact, it is possible to reduce the
resistance of the contact and to prevent voids from being formed in
the contact since the step coverage of the barrier film is
excellent.
[0099] The present invention is not restricted to the above
embodiments, and it is clearly understood that many variations are
possible within the scope and spirit of the present invention by
anyone skilled in the art.
* * * * *