U.S. patent application number 09/779565 was filed with the patent office on 2001-08-30 for semiconductor device and manufacturing method thereof.
This patent application is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Kamoshima, Takao, Takewaka, Hiroki, Yamashita, Takashi.
Application Number | 20010017415 09/779565 |
Document ID | / |
Family ID | 14874617 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010017415 |
Kind Code |
A1 |
Kamoshima, Takao ; et
al. |
August 30, 2001 |
Semiconductor device and manufacturing method thereof
Abstract
A semiconductor device with high reliability is provided in
which an insulating property of an insulating layer is high and
connection failure is prevented. The semiconductor device includes:
a silicon substrate; a low-temperature aluminum film formed on
silicon substrate and including a polycrystal; and a
high-temperature aluminum film. An opening is formed in a surface
of a high-temperature aluminum film by a crystal grain boundary. A
distance between side walls of the opening becomes small as closer
to silicon substrate.
Inventors: |
Kamoshima, Takao; (Hyogo,
JP) ; Takewaka, Hiroki; (Hyogo, JP) ;
Yamashita, Takashi; (Hyogo, JP) |
Correspondence
Address: |
McDermott, Will & Emery
600 13th Street, N.W.
Washington
DC
20005-3096
US
|
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha
Tokyo
JP
|
Family ID: |
14874617 |
Appl. No.: |
09/779565 |
Filed: |
February 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09779565 |
Feb 9, 2001 |
|
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09391388 |
Sep 8, 1999 |
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6214723 |
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Current U.S.
Class: |
257/750 ;
257/771; 257/773; 257/775; 257/E21.295; 257/E21.589; 257/E23.16;
438/688 |
Current CPC
Class: |
H01L 21/76885 20130101;
H01L 23/53223 20130101; H01L 21/32051 20130101; H01L 2924/0002
20130101; Y10S 438/978 20130101; H01L 2924/0002 20130101; H01L
2924/00 20130101 |
Class at
Publication: |
257/750 ;
257/771; 257/773; 257/775; 438/688 |
International
Class: |
H01L 021/44; H01L
023/48; H01L 023/52; H01L 029/40 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 1999 |
JP |
11-124002(P) |
Claims
What is claimed is:
1. A semiconductor device, comprising: a semiconductor substrate;
and a conductive layer formed on said semiconductor substrate and
including polycrystals, said conductive layer including in its
surface a recess caused by a crystal grain boundary and having side
walls formed such that a distance therebetween becomes small as
closer to said semiconductor substrate.
2. The semiconductor device according to claim 1, wherein said
conductive layer includes: a first conductive layer formed on said
semiconductor substrate and including a polycrystal having a first
average grain size; and a second conductive layer formed on said
first conductive layer, including a polycrystal having a second
average grain size greater than said first average grain size and
having said recess.
3. The semiconductor device according to claim 1, further
comprising a thin film layer formed on said conductive layer and
having a material different from that of said conductive layer.
4. The semiconductor device according to claim 1, wherein said
conductive layer includes aluminum.
5. The semiconductor device according to claim 1, further
comprising an insulating layer formed on said semiconductor
substrate and a barrier layer formed on said insulating layer, said
conductive layer being formed on said barrier layer.
6. A semiconductor device, comprising: a first conductive layer
formed on a semiconductor substrate and including a polycrystal
having a first average grain size; a second conductive layer formed
on said first conductive layer and including a polycrystal having a
second average grain size greater than said first average grain
size; and a third conductive layer formed on said second conductive
layer and including a polycrystal having a third average grain size
smaller than said second average grain size.
7. The semiconductor device according to claim 6, wherein a recess
is formed in a surface of said second conductive layer by a crystal
grain boundary, and a distance between side walls of said recess
becomes small as closer to said semiconductor substrate.
8. The semiconductor device according to claim 6, further
comprising a thin film layer formed on said third conductive layer
and having a material different from that said third conductive
layer.
9. The semiconductor device according to claim 6, wherein said
conductive layer includes aluminum.
10. The semiconductor device according to claim 6, further
comprising an insulating layer formed on said semiconductor
substrate and a barrier layer formed on said insulating layer, said
conductive layer being formed on said barrier layer.
11. A method of manufacturing a semiconductor device, comprising
the steps of: forming a conductive layer including a polycrystal on
a semiconductor substrate, said conductive layer having a recess in
its surface formed by a crystal grain boundary, a distance between
side walls of said recess becoming large as closer to said
semiconductor substrate; and processing said side walls of said
recess such that the distance therebetween becomes small as closer
to said semiconductor substrate.
12. The method of manufacturing the semiconductor device according
to claim 11, wherein said step of forming said conductive layer
includes the steps of: forming a first conductive layer on said
semiconductor substrate at a first temperature; and forming a
second conductive layer having said recess on said first conductive
layer at a second temperature higher than said first
temperature.
13. The method of manufacturing the semiconductor device according
to claim 11, further comprising the step of forming a thin film
layer having a material different from that of said conductive
layer on said conductive layer having the processed side walls.
14. The method of manufacturing the semiconductor device according
to claim 11, further comprising the step of forming an insulating
layer on said semiconductor substrate and the step of forming a
barrier layer on said insulating layer, said step of forming said
conductive layer including the step of forming said conductive
layer on said barrier layer.
15. The method of manufacturing the semiconductor device according
to claim 11, wherein said step of processing said side walls
includes the step of sputter etching said conductive layer.
16. A method of manufacturing a semiconductor device, comprising
the steps of: forming a first conductive layer on a semiconductor
substrate at a first temperature; forming a second conductive layer
on said first conductive layer at a second temperature higher than
said first temperature; and forming a third conductive layer on
said second conductive layer at a third temperature lower than said
second temperature.
17. The method of manufacturing the semiconductor device according
to claim 16, wherein said step of forming said second conductive
layer includes the step of forming said second conductive layer
with a recess formed in its surface by a crystal grain boundary and
having side walls, a distance between said side walls becoming
large as closer to said semiconductor substrate, said method
further comprising the step of processing said side walls such that
a distance therebetween becomes small as closer to said
semiconductor substrate, and wherein said step of forming said
third conductive layer includes the step of forming said third
conductive layer on said second conductive layer having said
processed side walls.
18. The method of manufacturing the semiconductor device according
to claim 16, wherein said step of processing said side walls
further includes the step of sputter etching said conductive
layer.
19. The method of manufacturing the semiconductor device according
to claim 16, further comprising the step of forming a thin film
layer having a material different from that of said third
conductive layer on said third conductive layer.
20. The method of manufacturing the semiconductor device according
to claim 16, further comprising the step of forming an insulating
layer on said semiconductor substrate and the step of forming a
barrier layer on said insulating layer, said step of forming said
conductive layer including the step of forming said conductive
layer on said barrier layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to semiconductor devices and
manufacturing methods thereof, and more particularly to a
semiconductor device having a conductive layer as an
interconnection layer and a manufacturing method thereof.
[0003] 2. Description of the Background Art
[0004] Conventionally, aluminum is used for an interconnection
layer of a semiconductor device. The problem related to a method of
manufacturing the interconnection with aluminum will be
described.
[0005] FIGS. 18 to 22 are cross sectional views shown in
conjunction with the problem associated with the conventional
manufacturing method.
[0006] Referring to FIG. 18, an interlayer insulating film 102 is
formed on a silicon substrate 101. A titanium nitride film 103 as a
barrier layer is formed on interlayer insulating film 102. An
aluminum film (hereinafter referred to as a high-temperature
aluminum film) 105 is formed on titanium nitride film 103 by
sputtering at a high temperature of about 400.degree. C.
[0007] The formation of the aluminum film at such high temperature
increases planarity of high-temperature aluminum film 105. A
crystal grain size of high-temperature aluminum film 105 is larger
than that of an aluminum film formed at a low temperature.
Therefore, when high-temperature aluminum film 105 is cooled, a
recess 106 is formed by the grain boundary, for example, due to
shrinkage of a crystal.
[0008] Referring to FIG. 19, an anti-reflection film 109 of
titanium nitride is formed on a surface of high-temperature
aluminum film 105. At the time, a thickness of anti-reflection film
109 is particularly small at a corner 106a of recess 106.
[0009] Referring to FIG. 20, resist is applied onto anti-reflection
film 109. After the resist is exposed to light, a resist pattern
110 is formed by development using developer. As the thickness of
anti-reflection film 109 is small at corner 106a of recess 106, the
developer melts a portion of anti-reflection film 109 and also a
portion of high-temperature aluminum film 105. Thus, recess 106
extends and an opening 107 is formed. Opening 107 is greater than
the opening at anti-reflection film 109.
[0010] Referring to FIG. 21, etching of anti-reflection film 109
and high-temperature aluminum film 105 is started using resist
pattern 110 as a mask. At the time, etch residue 111, formed by
reaction of high-temperature aluminum film 105 and etchant, is left
at a portion covered by anti-reflection film 109 in opening 107. It
is relatively difficult to etch etching residue 111.
[0011] Referring to FIG. 22, when etching is further performed,
etch residue 111 acts as a mask to leave high-temperature aluminum
film 105 and titanium nitride film 103 thereunder. As a result,
interconnection layers 112 and 113 are formed and, at the same
time, residues 121 and 122 including conductive portions are formed
at portions which would have essentially been free of such
conductive materials.
[0012] Formation of an interlayer insulating film on residues 121
and 122 would result in insulation failure of the interlayer
insulating film and reduction in reliability of the semiconductor
device.
SUMMARY OF THE INVENTION
[0013] The present invention is made to solve the aforementioned
problem. An object according to one aspect of the present invention
is to provide a semiconductor device provided with high reliability
and preventing insulation failure.
[0014] An object according to another aspect of the present
invention is to provide a semiconductor device provided with high
adhesion with a lower layer and preventing connection failure.
[0015] The semiconductor device according to one aspect of the
present invention includes a semiconductor substrate and a
conductive layer including polycrystal formed on the semiconductor
substrate. A recess is formed by a grain boundary in a surface of
the conductive layer. A distance between side walls of the recess
becomes small as closer to the semiconductor substrate.
[0016] In the semiconductor device having such structure, as the
distance between the side walls of the recess becomes small as
closer to the semiconductor substrate, there would be no space for
the residue caused by the etching in the recess in the conductive
layer and any conductive material is not left at the unexpected
portion. As a result, the semiconductor device provided with high
reliability and preventing insulation failure is provided.
[0017] More preferably, the conductive layer includes first and
second conductive layers. The first conductive layer is formed on
the semiconductor substrate and includes a polycrystal having a
first average grain size. The second conductive layer is formed
with a recess on the first conductive layer and includes a
polycrystal having a second average grain size which is greater
than the first average grain size.
[0018] As the first average grain size is relatively small as
compared with the second average grain size, adhesion between the
first conductive layer of the first average grain size and a lower
layer increases. Thus, the semiconductor device provided with high
reliability and preventing connection failure is provided.
[0019] More preferably, the semiconductor device further includes a
thin film layer formed on the conductive layer and having a
material which is different from that of the conductive layer.
[0020] More preferably, the thin film layer includes titanium or
silicon nitride. Then, the thin film layer can be used as a barrier
layer or anti-reflection layer.
[0021] More preferably, the conductive layer includes aluminum.
[0022] More preferably, the semiconductor device further includes
an insulating layer formed on the semiconductor substrate and a
barrier layer formed on the insulating layer. The conductive layer
is formed on the barrier layer.
[0023] Then, as the barrier layer is formed under the conductive
layer, diffusion of atoms of the conductive layer can be
prevented.
[0024] A semiconductor device according to another aspect of the
present invention includes first, second and third conductive
layers. The first conductive layer is formed on the semiconductor
substrate and includes a polycrystal having a first average grain
size. The second conductive layer is formed on the first conductive
layer and includes a polycrystal having a second average grain size
which is greater than the first average grain size. The third
conductive layer is formed on the second conductive layer and
includes a polycrystal having a third average grain size which is
smaller than the second average grain size.
[0025] In the semiconductor device having such structure, as the
average grain size of the third conductive layer formed on the
second conductive layer is small, formation of a recess by a grain
boundary in the third conductive layer is prevented. As there would
be no space for residue caused by etching in the third conductive
layer, a conductive material is not left at an unexpected portion.
As a result, the semiconductor device provided with high
reliability and preventing insulation failure is provided.
[0026] As a first average grain size of the first conductive layer
formed on the semiconductor substrate is relatively small, adhesion
with a lower layer is increased and connection failure can be
prevented.
[0027] More preferably, a recess is formed in a surface of the
second conductive layer by the grain boundary. A distance between
side walls of the recess becomes small as closer to the
semiconductor substrate.
[0028] Then, there would be no space for the residue caused by the
etching in the third conductive layer covering the recess. As a
result, the conductive material is not left at the unexpected
portion, so that reliability of the semiconductor device is further
increased.
[0029] More preferably, the semiconductor device further includes a
thin film layer formed on the third conductive layer and having a
material which is different from that of the third conductive
layer.
[0030] More preferably, the thin film layer includes titanium or
silicon nitride. Then, the thin film layer can be used as an
anti-reflection film or barrier layer.
[0031] More preferably, the conductive layer includes aluminum.
[0032] More preferably, the semiconductor device includes an
insulating layer formed on the semiconductor substrate and a
barrier layer formed on the insulating layer. The conductive layer
is formed on the barrier layer.
[0033] Then, as the barrier layer is formed under the conductive
layer, diffusion of atoms of the conductive layer can be
prevented.
[0034] A method of manufacturing a semiconductor device according
to one aspect of the present invention includes a step of forming a
conductive layer including a polycrystal on a semiconductor
substrate. The conductive layer having a recess in its surface
formed by a grain boundary. A distance between side walls of the
recess becomes large as closer to the semiconductor substrate. The
method of manufacturing the semiconductor device includes a step of
forming the side walls such that a distance therebetween becomes
small as closer to the semiconductor substrate.
[0035] In the method of manufacturing the semiconductor device
having such structure, the side walls prevents formation of a space
for the residue in the conductive layer. Thus, a conductive
material is not left at an unexpected portion, so that the
semiconductor device provided with high reliability and preventing
insulation failure is provided.
[0036] More preferably, the step of forming the conductive layer
includes a step of forming a first conductive layer at a first
temperature on the semiconductor substrate, and a step of forming a
second conductive layer having a recess at a second temperature
which is higher than the first temperature on the first conductive
layer.
[0037] As the first conductive layer is formed at the relatively
low temperature, adhesion between the first conductive layer and a
lower layer increases. As a result, the semiconductor device
provided with high reliability and preventing connection failure is
provided.
[0038] More preferably, the step of forming the second conductive
layer includes a step of keeping the second conductive layer in the
atmosphere at the second temperature after the second conductive
layer is formed by sputtering at a temperature which is lower than
the second temperature.
[0039] More preferably, the method of manufacturing the
semiconductor device further includes a step of forming a thin film
layer having a material which is different from that of the
conductive layer on the conductive layer having the formed side
walls.
[0040] More preferably, the method of manufacturing the
semiconductor device further includes a step of forming an
insulating layer on the semiconductor substrate and a step of
forming a barrier layer on the insulating layer. The step of
forming the conductive layer includes a step of forming a
conductive layer on the barrier layer.
[0041] Then, as the barrier layer is formed under the conductive
layer, diffusion of atoms of the conductive layer is prevented.
[0042] More preferably, the step of forming the side walls includes
a step of sputter etching the conductive layer.
[0043] A method of manufacturing a semiconductor device according
to another aspect of the present invention includes a step of
forming a first conductive layer on a semiconductor substrate at a
first temperature, a step of forming a second conductive layer on
the first conductive layer at a second temperature higher than the
first temperature, and a step of forming a third conductive layer
on the second conductive layer at a third temperature lower than
the second temperature.
[0044] In the method of manufacturing the semiconductor device
having such structure, as the third conductive layer is formed at
the relatively low temperature, formation of a recess in a surface
of the third conductive layer by a grain boundary is prevented.
Thus, there would be no space for a residue caused by the etching
in the surface of the third conductive layer. As a result, any
conductive material is not left at an unexpected portion, so that
the semiconductor device provided with high reliability and
preventing insulation failure is provided.
[0045] As the first conductive layer is formed at the relatively
low temperature, adhesion with a lower layer increases. Thus, the
semiconductor device provided with high reliability and preventing
connection failure is provided.
[0046] Preferably, the step of forming the second conductive layer
includes a step of forming a second conductive layer having in its
surface a recess caused by the grain boundary, where a distance
between side walls of the recess becomes large as closer to the
semiconductor substrate. The method of manufacturing the
semiconductor device further includes a step of forming the side
walls such that the distance therebetween becomes small as closer
to the semiconductor substrate. The step of forming the third
conductive layer includes a step of forming the third conductive
layer on the second conductive layer having the formed side
walls.
[0047] As the side walls of the recess are thus formed, even when
the third conductive layer is formed thereon, there would be no
space for the residue caused by the etching in the third conductive
layer. As a result, any conductive material is not left at the
unexpected portion, so that the semiconductor device provided with
higher reliability and preventing insulating failure is
provided.
[0048] More preferably, the step of forming the side walls includes
a step of sputter etching the conductive layer.
[0049] More preferably, the method of manufacturing the
semiconductor device further includes a step of forming a thin film
layer having a material which is different from that of the third
conductive layer on the third conductive layer.
[0050] The step of forming the second conductive layer includes a
step of keeping the second conductive layer in the atmosphere at
the second temperature after the second conductive layer is formed
by sputtering at a temperature lower than the second
temperature.
[0051] More preferably, the method of manufacturing the
semiconductor device further includes a step of forming an
insulating layer on the semiconductor substrate and a step of
forming a barrier layer on the insulating layer. The step of
forming the conductive layer includes a step of forming a
conductive layer on the barrier layer. Then, as the conductive
layer is formed on the barter layer, diffusion of atoms of the
conductive layer is prevented.
[0052] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1A is a schematic cross sectional view showing a
semiconductor device according to a first embodiment of the present
invention, and FIG. 1B is a partial cross sectional view showing in
enlargement an opening in the semiconductor device according to the
first embodiment of the present invention.
[0054] FIG. 2 is a cross sectional view showing a first step of a
method of manufacturing the semiconductor device shown in FIG.
1.
[0055] FIG. 3 is a partial cross sectional view showing in
enlargement a recess of the semiconductor device shown in FIG.
2.
[0056] FIGS. 4 to 7 are cross sectional views showing second to
fifth steps of the method of manufacturing the semiconductor device
shown in FIG. 1.
[0057] FIG. 8 is a cross sectional view showing a semiconductor
device according to a second embodiment of the present
invention.
[0058] FIGS. 9 to 12 are cross sectional views showing first to
fourth steps of a method of manufacturing the semiconductor device
shown in FIG. 8.
[0059] FIG. 13 is a cross sectional view showing a semiconductor
device according to a third embodiment of the present
invention.
[0060] FIGS. 14 to 17 are cross sectional views showing first to
fourth steps of a method of manufacturing the semiconductor device
shown in FIG. 13.
[0061] FIGS. 18 to 22 are cross sectional views showing first to
fifth steps of a method of manufacturing a conventional
semiconductor device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0062] Embodiments of the present invention will now be described
with reference to the drawings.
[0063] First Embodiment
[0064] Referring to FIG. 1A, in a semiconductor device according to
the present invention, an interlayer insulating film 2 is formed on
a silicon substrate 1 as a semiconductor substrate. An
interconnection layer 12 is formed on interlayer insulating film 2.
Interconnection layer 12 includes: a titanium nitride film 3 as a
barrier layer; a low-temperature aluminum layer (an aluminum layer
formed at a low temperature) 4 as a first conductive layer; a
high-temperature aluminum layer 5 as a second conductive layer; and
an anti-reflection film 9 as a thin film layer having two layers of
titanium and titanium nitride.
[0065] Titanium nitride film 3 has a thickness of about 100 nm. A
thickness of low-temperature aluminum film 4 including
polycrystalline aluminum is about 150 nm and has an average crystal
grain size of about 0.5 .mu.m. High-temperature aluminum film 5 is
formed on low-temperature aluminum film 4. A thickness of
high-temperature aluminum film is about 200 nm. High-temperature
aluminum film 5 includes polycrystalline aluminum and has an
average crystal grain size of about 1.5 .mu.m. An opening 107 is
formed as a recess in a surface of high-temperature aluminum film
5.
[0066] Referring to FIG. 1B, opening 7 is defined by grain
boundaries of crystals 5a to 5c of aluminum. Opening 7 has a depth
D of 20 nm, a diameter W.sub.1 at its upper portion of about 50 nm
and a diameter W.sub.2 at its bottom portion of 30 nm. A distance
between side walls 7a and 7b of opening 7 becomes small as closer
to silicon substrate 1.
[0067] Now, a method of manufacturing the semiconductor device
shown in FIG. 1 will be described. Referring to FIG. 2, an
interlayer insulating film 2 is formed by CVD (Chemical Vapor
Deposition) on a surface of silicon substrate 1. A titanium nitride
film 3 is formed on interlayer insulating film 2 by PVD Physical
Vapor Deposition).
[0068] A low-temperature aluminum film 4 is formed on titanium
nitride film 3 by sputtering at a low temperature of about
100.degree. C. High-temperature aluminum film 5 is formed on
low-temperature aluminum film 4 by sputtering at a high temperature
of about 400.degree. C. Thereafter, high-temperature aluminum film
5 is cooled, and a recess 6 is formed in a surface thereof by
crystal depression.
[0069] Referring to FIG. 3, recess 6 is formed by grain boundaries
of crystals 5a to 5c of aluminum, that is, crystal grain boundaries
of aluminum. Recess 6 is formed by depression of crystal 5b of
aluminum.
[0070] Returning to FIG. 2, the largest portion of recess 6 has a
diameter W.sub.2, and a diameter at the surface of high-temperature
aluminum film 5 is W.sub.3 (20 nm). A distance between side walls
6a and 6b of recess 6 becomes small as closer to silicon substrate
1.
[0071] Referring to FIG. 4, the surface of high-temperature
aluminum film 5 is sputter etched using argon gas. Thus, opening 7
is formed by processing the side walls of recess 6. A distance
between side walls 7a and 7b of opening 7 becomes small as doser to
silicon substrate 1. A corner 7c of opening 7 is arcuate in
shape.
[0072] Referring to FIG. 5, an anti-reflection film 9 having two
layers of titanium and titanium nitride is formed by PVD to cover
high-temperature aluminum film 5.
[0073] Referring to FIG. 6, resist is applied onto anti-reflection
film 9. After the resist is exposed to light, it is developed by
developer to form a resist pattern 10.
[0074] Referring to FIG. 7, anti-reflection film 9,
high-temperature aluminum film 5, low-temperature aluminum film 4
and titanium nitride film 3 are etched in accordance with resist
pattern 10. Thus, an interconnection layer 12 is formed.
Thereafter, resist pattern 10 is removed to complete the
semiconductor device shown in FIG. 1.
[0075] According to the semiconductor device and manufacturing
method thereof, first, side walls 7a and 7b of opening 7 are formed
as shown in FIG. 4. As anti-reflection film 9 is formed over
opening 7, any particular portion of anti-reflection film 9 would
not have extremely small thickness. Thus, if the resist is
developed in the step shown in FIG. 6, formation of a space for
etch residue is prevented. As a result, etching in accordance with
resist pattern 10 ensures that a conductive material is left
exclusively under resist pattern 10 and the other portion would be
free of the conductive material. Therefore, the semiconductor
device is provided with higher reliability.
[0076] Low-temperature aluminum film 4 is formed on titanium
nitride film 3. As low-temperature aluminum film 4 is provided with
high adhesion with other layers, the semiconductor device provided
with high reliability and preventing connection failure is
achieved.
[0077] Second Embodiment
[0078] Referring to FIG. 8, silicon substrate 1, interlayer
insulating film 2, titanium nitride film 3 and low-temperature
aluminum film 4 are the same as those of the first embodiment.
[0079] A high-temperature aluminum-film 5 is formed on
low-temperature aluminum film 4. High-temperature aluminum film 5
has an average grain size of 1.5 .mu.m and a thickness of 200 nm. A
recess 6 is formed in a surface of high-temperature aluminum film
5. A dimension of recess 6 is the same as that shown in FIG. 2.
[0080] Low-temperature aluminum film 21 is formed over recess 6.
Low-temperature aluminum film 21 has a thickness of 100 nm and an
average grain size of 0.1 .mu.m. A distance between side walls 6a
and 6b of recess 6 becomes small as closer to silicon substrate 1.
An anti-reflection film 22 having two layers of titanium and
titanium nitride is formed on low-temperature aluminum film 21.
[0081] Now, a method of manufacturing the semiconductor device
shown in FIG. 8 will be described. Referring to FIG. 9, as in the
first embodiment, an interlayer insulating film 2, titanium nitride
film 3, low-temperature aluminum film 4 and high-temperature
aluminum film 5 are formed on silicon substrate 1. Recess 6 is
formed in the surface of high-temperature aluminum film 5.
[0082] Referring to FIG. 10, low-temperature aluminum film 21 is
formed by sputtering at a temperature of about 100.degree. C. An
anti-reflection film 22 is formed on low-temperature aluminum film
21 by PVD.
[0083] Referring to FIG. 11, resist is applied onto anti-reflection
film 22. After the resist is exposed to light, it is developed by a
developer to form a resist pattern 23.
[0084] Referring to FIG. 12, anti-reflection film 22,
low-temperature aluminum film 21, high-temperature aluminum film 5,
low-temperature aluminum film 4 and titanium nitride film 3 are
etched in accordance with resist pattern 23. Thus, an
interconnection layer 25 is formed. Thereafter, resist pattern 23
is removed to complete the semiconductor device shown in FIG.
8.
[0085] According to the semiconductor device and manufacturing
method thereof, low-temperature aluminum film 21 is formed in
recess 6. As the average grain size of low-temperature aluminum
film 21 is relatively small, it is unlikely that depression of a
crystal is caused. Thus, even when anti-reflection film 22 is
formed on low-temperature aluminum film 21, any portion of
anti-reflection film 22 would not have a smaller thickness.
Therefore, low-temperature aluminum film 21 would not be etched at
the time of development of resist pattern 23, and there is not any
space for the etch residue. In addition, insulation failure is
prevented. As shown in FIG. 12, the conductive material is left
exclusively under resist pattern 23, and the other portion would be
free of conductive material. As a result, the semiconductor device
with high reliability is achieved.
[0086] Low-temperature aluminum film 4 is formed on titanium
nitride film 3. As low-temperature aluminum film 4 has high
adhesion with other layers, connection failure is prevented. As a
result, the semiconductor device with high reliability is
achieved.
[0087] Third Embodiment
[0088] Referring to FIG. 13, an interlayer insulating film 2,
titanium nitride film 3, low-temperature aluminum film 4 and
high-temperature aluminum film 5 are formed on a silicon substrate
1. An opening 7 is formed in a surface of high-temperature aluminum
film 5, and a distance between side walls 7a and 7b of opening 7
becomes small at closer to silicon substrate 1. Low-temperature
aluminum film 31 is formed in opening 7.
[0089] An anti-reflection film 32 having two layers of titanium and
titanium nitride is formed on low-temperature aluminum film 31.
Titanium nitride film 3, low-temperature aluminum film 4,
high-temperature aluminum film 5, low-temperature aluminum film 31
and anti-reflection film 32 comprise an interconnection layer
35.
[0090] Now, a method of manufacturing the semiconductor device
shown in FIG. 13 will be described. Referring to FIG. 14, as in the
steps shown in FIGS. 2 and 4 of the first embodiment, interlayer
insulating film 2, titanium nitride film 3, low-temperature
aluminum film 4 and high-temperature aluminum film 5 are formed on
silicon substrate 1. Opening 7 is formed by sputter etching the
surface of high-temperature aluminum film 5 by argon. The distance
between side walls 7a and 7b of opening 7 becomes small as closer
to silicon substrate 1.
[0091] Referring to FIG. 15, low-temperature aluminum film 31 is
formed to cover opening 7 by sputtering at a temperature of about
100.degree. C. Anti-reflection film 32 having two layers of
titanium and titanium nitride is formed on low-temperature aluminum
film 31 by CVD.
[0092] Referring to FIG. 16, resist is applied onto anti-reflection
film 32. After the resist is exposed to light, it is developed by
developer. Thus, a resist pattern 33 is formed.
[0093] Referring to FIG. 17, anti-reflection film 32,
low-temperature aluminum film 31, high-temperature aluminum film 5,
low-temperature aluminum film 4 and titanium nitride film 3 are
etched in accordance with resist pattern 33 to form an
interconnection layer 35. Thereafter, resist pattern 33 is removed
to complete the semiconductor device shown in FIG. 13.
[0094] According to the semiconductor device and manufacturing
method thereof, first, low-temperature aluminum film 31 is formed
on high-temperature aluminum film 5 at a low temperature as shown
in FIG. 15. As a crystal grain size of low-temperature aluminum
film 31 is relatively small, it is unlikely that a recess is formed
in low-temperature aluminum film 31. Recess 6 in the
high-temperature aluminum film is processed to be tapered opening
7, so that a surface of low-temperature aluminum film 31 is almost
planar. Accordingly, even when anti-reflection film 32 is formed on
low-temperature aluminum film 31, any portion of anti-reflection
film 32 would not have a smaller thickness. Therefore,
low-temperature aluminum film 31 is not etched at the time of
development of resist pattern 33, whereby formation of a space for
the etch residue is prevented. As a result, a conductive material
is left exclusively under resist pattern 33 and the other portions
are substantially flee of the conductive material, as shown in FIG.
12. Therefore, the semiconductor device provided with high
reliability and preventing connection failure is achieved.
[0095] As high-temperature aluminum film 4 with high adhesion with
other material is formed on titanium nitride film 3, semiconductor
device with high reliability and preventing connection failure is
achieved.
[0096] Although the embodiments of the present invention have been
described above, various modifications can be made to the
embodiments. For example, in the above sputtering at the high
temperature has been exemplified as a method of forming
high-temperature aluminum film 5. However, the method is not
limited to this and, for example, a so-called high temperature
reflow method may be used in which an aluminum film is formed by
sputtering at a low temperature of about 100.degree. C. and the
aluminum film is kept at a high temperature of about 400.degree.
C.
[0097] Although anti-reflection film 9 has been described as having
two layers of titanium and titanium nitride, a silicon nitride film
may be used as the anti-reflection film. Further, though aluminum
has been described as the conductive material of the
interconnection layer, copper or tungsten may be employed.
[0098] In some cases, a boundary between low temperature having
aluminum film 4 and high-temperature aluminum film 5 is not clearly
defined. Then, a portion of low-temperature aluminum film 4 that is
closer to titanium nitride film 3 has a relatively small grain
size, whereas the portion closer to high temperature having
aluminum film 5 has a relatively large grain size.
[0099] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
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