Method for manufacturing aluminum wired layer for interconnecting device to device in a semiconductor device

An improved aluminum wired layer for interconnecting a device to another device and which comprises a plurality of aluminum wired layers formed on an insulating layer of a semiconductor device and the method of manufacturing such aluminum wired layer is disclosed. The improvement of the aluminum wired layer comprises a plurality of aluminum wired layers positioned on the insulating layer, with each aluminum wired layer being spaced relative to each other and having a top, side walls and a bottom. A first Al-Ti compound metal layer is formed on the top and on the side walls of each aluminum wired layer to prevent the formation of hillock on the surface of each aluminum wired layer during the heat treatment process and to prevent electromigration phenomenon in each aluminum wired layer when the semiconductor device is in operation.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The present invention relates to an aluminum wired layer for 
interconnecting devices on a semiconductor device and a method of 
manufacturing an aluminum wired layer, and more particularly to an 
aluminum wired layer for interconnecting devices on a semiconductor 
device, with the aluminum wired layer being formed with an Al-Ti compound 
metal layer on the periphery of the aluminum wired layer, for example, 
top, bottom and side walls, and to a method of manufacturing such aluminum 
wired layer. 
In general, in manufacturing a semiconductor device, the material of the 
aluminum wired layer interconnecting the devices for certain purposes 
formed inside the semiconductor device is a material which has excellent 
electric conductivity and which easily accepts the depositing process and 
the mask patterning process as final processes. Aluminum is the most 
widely used material. 
The advantages of aluminum, in addition to the above description, are its 
good adherence to the top of the oxide film during the wiring process and 
its ability to bond with gold wire or aluminum wire. Further, aluminum is 
inexpensive. 
On the other hand, aluminum has various problems. First, silicon diffuses 
from the silicon substrate into the aluminum wired layer at the junction 
positioned between the aluminum wired layer and the silicon substrate. 
This results in the formation of an undesirable pit in a portion of the 
junction which destroys the junction. This occurs when manufacturing an 
aluminum wired layer on a silicon substrate when heat (400-500 degree 
Celsius) is used to enhance the junction between the aluminum wired layer 
and the silicon substrate. This also occurs in other heat treatment 
processes, such as the depositing process (350-450 degree Celsius) where 
an insulation layer is deposited on the aluminum wired layer after the 
aluminum wired layer is formed on the silicon substrate. In view of the 
above, silicon is added, approximately 1% by weight, to the aluminum which 
will form the aluminum wired layer. The silicon is added to prevent the 
silicon of the substrate from diffusing into the aluminum wired layer 
during heat treatment of the aluminum wired layer. The metal barrier 
layer, such as TiW (Titanium - Tungsten) layer (10% Titanium/90% Tungsten) 
or TiN (Titanium - Nitride) layer can also be used to prevent the silicon 
of the substrate from diffusing into the aluminum wired layer during heat 
treatment of the aluminum wired layer deposited thereon. 
Second, in the heat treatment process described above, a hillock of 
aluminum projecting from the surface of the aluminum wired layer occurs 
due to the difference in the thermal expansion coefficient between the 
aluminum wired layer and the substrate below the layer. Thus, when 
depositing a protecting film on the entire structure after the process of 
forming the aluminum wired layer for an internal connection line and 
performing the process of packaging the device, if the lithographic 
etching process utilizing a photoresist is performed for removing only a 
portion of the protecting film, such as for example, the bonding pad 
portion at which an aluminum wired layer for external connecting line is 
connected to the aluminum wired layer for internal connection line, the 
hillock causes a problem that the protecting film cannot protect against 
because the photoresist cannot cover completely the surface of the 
aluminum wired layer except for a portion of the bonding pad portion such 
that the protecting layer at the hillock is undesirably etched away. 
Furthermore, in the case of forming a multi-layered metal wired layer, a 
pin hole is produced at the insulating layer due to the hillock so that 
the lower aluminum wired layer and the upper aluminum wired layer are 
electrically connected to each other at an undesirable position rendering 
the device inoperable. 
Third, when the device operates, the flow of electric current in the 
aluminum wired layer results in an electromigration phenomenon in which 
the atoms of the aluminum move so that the aluminum wired layer becomes 
disconnected. 
One of the methods of the prior art to solve hillock formatting on the 
surface of the aluminum wired layer and the problem of the 
electromigration is to deposit an aluminum layer and a titanium layer in 
sequence, as shown in FIG. 1. A plurality of the aluminum wired layers is 
then formed by removing certain portions of the aluminum and the titanium 
layers by the mask patterning process. An Al-Ti compound metal layer is 
formed on the top of the aluminum wired layer by heat treatment. The Al-Ti 
compound metal layer restrains the occurrence of hillock formation and 
reduces the electromigration phenomenon. In the prior art process the 
Al-Ti compound metal layer is obtained by heat treatment of the aluminum 
wired layer and the titanium layer at the temperature of about 350-450 
degree Celsius. It is noted that if the silicon is added in the order of 
less that 2% by weight in the aluminum, the Al-Ti compound metal layer is 
composed of the Al.sub.3 Ti. 
However, with the prior art method, while the hillock on the top of the 
aluminum wired layer can be restrained, the hillock projected from the 
side wall of the aluminum wired layer cannot be restrained. However, the 
spacing between the adjacent aluminum wired layers is small making 
adjacent layers undesirably connected to each other where the hillock 
occurs at the side wall. This results in a failure of the device. 
Therefore, an object of the present invention is to provide an aluminum 
wired layer for connecting device to device in a semiconductor device 
constructed in such a way that the Al-Ti compound metal layer is formed 
over the entire exposed surface of the top, bottom and side walls of the 
aluminum wired layer. 
A further object of the present invention is to provide a method for 
forming a protected aluminum wired layer. 
A further object of the present invention is to provide an aluminum wired 
layer for connecting device to device which restrains the occurrence of 
hillock formation not only on the top but also on the side walls of the 
aluminum wired layer. 
A further object of the present invention is to provide an aluminum wired 
layer for connecting device to device which prevents the occurrence of the 
destruction of the junction between the aluminum wired layer and the 
silicon substrate, and which prevents the electromigration phenomenon in 
the aluminum wired layer. 
The preceeding objects should be construed as merely presenting a few of 
the more pertinent features and applications of the invention. Many other 
beneficial results can be obtained by applying the disclosed invention in 
a different manner or modifying the invention within the scope of the 
disclosure. Accordingly, other objects and a fuller understanding of the 
invention may be had by referring to both the summary of the invention and 
the detailed description, below, which describe the preferred embodiment 
in addition to the scope of the invention defined by the claims considered 
in conjunction with the accompanying drawings. 
SUMMARY OF THE INVENTION 
The aluminum wire layer for interconnecting device to device in a 
semiconductor device of the present invention is defined by the claims 
with a specific embodiment shown in the attached drawings. For the purpose 
of summarizing the invention, the invention relates to an improvement in 
an aluminum wired layer for interconnecting device to device which 
comprises a plurality of aluminum wired layers formed on an insulating 
layer of a semiconductor device. The improvement of the aluminum wired 
layer comprises a plurality of aluminum wired layers on the insulating 
layer, with each aluminum wired layer being spaced relative to each other 
and having a top, side walls and a bottom, respectively. A first Al-Ti 
compound metal layer is formed on the top and on the side walls of each 
aluminum wired layer to prevent the formation of hillock on the surface of 
each aluminum wired layer during the heat treatment and to prevent 
electromigration phenomenon in each aluminum wired layer when the 
semiconductor device is in operation. 
The aluminum wired layer according to the present invention further include 
a second Al-Ti compound metal layer formed on each bottom of each aluminum 
wired layer of the plurality of aluminum wired layers. 
A further embodiment of the present invention includes an aluminum wired 
layer for interconnecting device to device comprising a plurality of 
aluminum wired layers formed on a silicon substrate of a semiconductor 
device, wherein the improvement of the aluminum wired layer comprises a 
plurality of aluminum wired layers on the silicon substrate, with each 
aluminum wired layer being spaced apart relative to each other and having 
a top, side walls and a bottom. A first Al-Ti compound metal layer is 
formed on the top and side walls of each aluminum wired layer of the 
plurality of aluminum wired layers. A metal barrier layer is formed on 
each bottom of each aluminum wired layer of the plurality of aluminum 
wired layers to prevent the formation of a pit occurring at a junction 
between the silicon substrate and each aluminum wired layer during heat 
treatment and to prevent electromigration phenomenon in each aluminum 
wired layer when the semiconductor device is in operation. 
This embodiment may further include a second Al-Ti compound metal layer 
formed on the bottom of each aluminum wired layer of the plurality of 
aluminum wired layers. A metal barrier layer formed between the silicon 
substrate and each second Al-Ti compound metal layer of each aluminum 
wired layer of the plurality of aluminum wired layers thereby restraining 
electromigration phenomenon and preventing the formation of hillock on the 
surface of each aluminum wired layer during heat treatment. The preferred 
metal barrier layer are a Titanium - Tungsten layer having a composite 
rate of 10-90 percentage and a Titanium - Nitrogen layer. 
The present invention further includes a method for manufacturing an 
aluminum wired layer for interconnecting device to device comprising a 
plurality of aluminum wired layers formed on an insulating layer of a 
semiconductor device, wherein the improvement of the aluminum wired layer 
comprises depositing an aluminum layer on the insulating layer and then 
etching the aluminum layer deposited on the surface of the insulating 
layer to form a plurality of aluminum wired layers with each aluminum 
wired layer being spaced apart relative to each other on the insulating 
layer exposed by the formation of the plurality of aluminum wired layers 
and with each aluminum wired layer having a top and side walls. A titanium 
layer is then deposited on the entire surface of the structure including 
each aluminum wired layer and the exposed portion of the insulating layer. 
The titanium layer is heated thereby reacting the titanium of the titanium 
layer positioned on each aluminum wired layer with the aluminum of each 
aluminum wired layer, to provide a first Al-Ti compound metal layer on the 
top and side walls of the each aluminum wired layer to prevent the 
formation of hillock on the surface of each aluminum wired layer during 
the heat treatment of the titanium layer and to prevent electromigration 
phenomenon in each aluminum wired layer when the semiconductor device is 
in operation. The titanium layer remaining on the exposed portion of the 
insulating layer is selectively removed. 
The titanium layer is heated at a temperature of 400-500 degree Celsius 
simultaneously with application of conditioning gases wherein the 
conditioning gas is selected form the group consisting of: a 
nitrogen-hydrogen gas mixture, nitrogen gas or argon gas. 
The titanium layer which remains on the exposed portion of the insulating 
layer is selectively removed by etching the remaining titanium layer in an 
etchant of NH.sub.4 OH/H.sub.2 O.sub.2 /H.sub.2 O having a composite ratio 
of 1:1:5 having a temperature of 18-40 degree Celsius. 
The present invention further includes a method for manufacturing an 
aluminum wired layer for interconnecting device to device comprising a 
plurality of aluminum wired layers formed on an insulating layer of a 
semiconductor device, wherein the improvement of the aluminum wired layer 
comprises sequentially depositing a first titanium layer and an aluminum 
layer on the insulating layer. The first titanium layer and the aluminum 
layer deposited on the surface of the insulating layer are etched to form 
a plurality of aluminum wired layers with each aluminum wired layer being 
spaced apart relative to each other on the insulating layer exposed by the 
formation of the plurality of aluminum wired layers and with each aluminum 
wired layer having a top, a bottom and side walls. A second titanium layer 
is deposited on the entire surface of the structure including each 
aluminum wired layer and on the exposed portion of the insulating layer. 
The first and second titanium layers are heated thereby reacting the 
titanium of the first and second titanium layers positioned on each 
aluminum wired layer and at the bottom thereof with the aluminum of each 
aluminum wired layer thereby providing a first Al-Ti compound metal layer 
on the top and side walls of each aluminum wired layer and a second Al-Ti 
compound metal layer at the bottom thereof to prevent the formation of 
hillock on the surface of each aluminum wired layer during the heat 
treatment and to prevent electromigration phenomenon in each aluminum 
wired layer when the semiconductor device is in operation. The second 
titanium layer remaining on the exposed portion of the insulating layer is 
selectively removed. 
The first and the second titanium layers are preferably heated at a 
temperature of 400-500 degree Celsius simultaneously with application of 
conditioning gases wherein the conditioning gas is selected form the group 
consisting of: a nitrogen-hydrogen gas mixture, nitrogen gas or argon gas. 
The second titanium layer remaining on the exposed portion of the 
insulating layer is selectively removed by etching the remaining titanium 
layer in an etchant of NH.sub.4 OH/H.sub.2 O.sub.2 /H.sub.2 O having a 
composite ratio of 1:1:5 and having a temperature of 18-40 degree Celsius. 
The present invention further includes a method for manufacturing an 
aluminum wired layer for interconnecting device to device comprising a 
plurality of aluminum wired layers formed on a silicon substrate of a 
semiconductor device, wherein the improvement of the aluminum wired layer 
comprises sequentially depositing a metal layer and an aluminum layer on 
the silicon substrate. The aluminum layer and the metal layer deposited on 
the surface of the silicon substrate are etched to form a plurality of 
aluminum wired layers with each aluminum wired layer being positioned on a 
metal barrier layer and spaced apart relative to each other on the silicon 
substrate exposed by the formation of the plurality of aluminum wired 
layers and with each aluminum wired layer having a top, a bottom and side 
walls. A titanium layer is deposited on the entire surface of the 
structure including on the each aluminum wired layer and on the exposed 
portion of the silicon substrate. The titanium layer is heated thereby 
reacting the titanium of the titanium layer positioned on the each 
aluminum wired layer with the aluminum of the each aluminum wired layer to 
provide a first Al-Ti compound metal layer on the top and side walls to 
prevent the formation of a pit occurring at a junction between the silicon 
substrate and each aluminum wired layer during heat treatment and to 
prevent electromigration phenomenon in each aluminum wired layer when the 
semiconductor device is in operation. The remaining titanium layer on the 
exposed portion of the silicon substrate is then selectively removed. 
Preferably, the titanium layer is heated at a temperature of 400-500 degree 
Celsius simultaneously with application of conditioning gases wherein the 
conditioning gas is selected form the group consisting of: a 
nitrogen-hydrogen gas mixture, nitrogen gas or argon gas. 
The titanium layer remaining on the exposed portion of the insulating layer 
is selectively removed by etching the remaining titanium layer in an 
etchant of NH.sub.4 OH/H.sub.2 O.sub.2 /H.sub.2 O having a composite ratio 
of 1:1:5 having a temperature of 18.varies.40 degree Celsius. 
A further embodiment of the present invention includes a method for 
manufacturing an aluminum wired layer for interconnecting device to device 
comprising a plurality of aluminum wired layers formed on a silicon 
substrate of a semiconductor device, wherein the improvement of the 
aluminum wired layer comprises sequentially depositing a metal layer, a 
first titanium layer and an aluminum layer on the silicon substrate. The 
aluminum layer, the first titanium layer and the metal layer deposited on 
the surface of the silicon substrate are then etched to form a plurality 
of aluminum wired layers with each aluminum wired layer being positioned 
on a metal barrier layer and spaced apart relative to each other on the 
silicon substrate exposed by the formation of the plurality of aluminum 
wired layers. Each aluminum wired layer has a top, a bottom and side 
walls. A second titanium layer is deposited on the entire surface of the 
structure including each aluminum wired layer and on the exposed portion 
of the silicon substrate. The first and second titanium layers are heated 
thereby reacting the titanium of the first and second titanium layers 
positioned on each aluminum wired layer and at the bottom thereof with the 
aluminum of the each aluminum wired layer, to provide a first Al-Ti 
compound metal layer on the top, side walls and a second Al-Ti compound 
metal layer on the bottom of the each aluminum wired layer to prevent the 
formation of a pit occurring at a junction between the silicon substrate 
and each aluminum wired layer during heat treatment and to prevent 
electromigration phenomenon in each aluminum wired layer when the 
semiconductor device is in operation. The second titanium layer remaining 
on the exposed portion of the silicon substrate is then selectively 
removed. 
Preferably, the first and the second titanium layers are heated at a 
temperature of 400-500 degree Celsius simultaneously with application of 
conditioning gases wherein the conditioning gas is selected form the group 
consisting of: a nitrogen-hydrogen gas mixture, nitrogen gas or argon gas. 
The second titanium layer remaining on the exposed portion of the 
insulating layer is selectively removed by etching the remaining titanium 
layer in an etchant of NH.sub.4 OH/H.sub.2 O.sub.2 /H.sub.2 O having a 
composite ratio of 1:1:5 having a temperature of 18-40 degree Celsius. 
The more pertinent and important features of the present invention have 
been outlined above in order that the detailed description of the 
invention which follows will be better understood and that the present 
contribution to the art can be fully appreciated. Additional features of 
the invention described hereinafter form the subject of the claims of the 
invention. Those skilled in the art can appreciate that the conception and 
the specific embodiment disclosed herein may be readily utilized as a 
basis for modifying or designing other structures for carrying out the 
same purposes of the present invention. Further, those skilled in the art 
can realize that such equivalent constructions do not depart from the 
spirit and scope of the invention as set forth in the claims.

The novel feature of the present invention may be understood from the 
accompanying description when taken in conjunction with the accompanying 
drawing. 
DETAILED DESCRIPTION OF THE DRAWINGS 
While the invention has been described with respect to the preferred 
embodiments using an aluminum wired layer and an aluminum wired layer with 
an aluminum wired layer formed on an insulating layer or a silicon 
substrate. It should be noted that the invention can applies to a 
semiconductor device in which the aluminum wired layer is used as a 
transistor, capacitor or resistor, etc. 
FIG. 1 illustrates a cross sectional view of an aluminum wired layer 
according to the prior art. Referring to the drawing, an aluminum layer 2 
and a titanium layer 3 are sequentially deposited on an insulating layer 
1. By the mask patterning process, the aluminum layer 2 and the titanium 
layer 3 are sequentially etched to provide a plurality of aluminum wired 
layers 2AA, with each aluminum wired layer 2A having a top 2B and being 
spaced apart relative to each other on the insulating layer 1. 
The plurality of aluminum wired layers 2AA on the insulating layer 1 are 
heated in a furnace, not shown, which is supplied with conditioning gases 
as described below, to cause the titanium to react with the aluminum in 
the each aluminum wired layer 2A, thereby forming an Al-Ti compound metal 
layer 4 on each of top 2B of each aluminum wired layer 2A. 
As described above, since the resultant structure of the aluminum wired 
layer according to the prior art has the Al-Ti compound metal layer 4 
formed directly on the top 2B of the each aluminum wired layer 2A, the 
problem of hillock formation at the side wall of the aluminum wired layer 
during heat treatment cannot be avoided. 
The first embodiment of the present invention provides a structure having a 
first Al-Ti compound metal layer 4A formed on the top 2B and side walls 2C 
of the each aluminum wired layer 2A. "Side walls" is used to describe the 
walls of the wired layer. Such wired layer includes the long side walls 
typical of a wired layer and the terminal walls which are typically very 
short relative to the side walls. The purpose of the present invention is 
to prevent the problems described above. Thus, all the walls of the wired 
layer are protected according to the present invention. The second 
embodiment of the present invention provides a structure having a first 
Al-Ti compound metal layer 4A formed on the top 2B, bottom 2D and side 
walls 2C of the each aluminum wired layer 2A. 
FIGS. 2A through 2C are sectional views of partially completed aluminum 
wired layers according to the process steps of the first embodiment of the 
present invention for manufacturing an aluminum wired layer on the 
insulating layer 1. The metal wire layer produced by the first embodiment 
of the present invention effectively prevents hillock formation at the top 
and side walls of the aluminum wired layer. 
Referring to FIG. 2A, to form a plurality of aluminum wired layers 2AA, an 
aluminum layer 2 is deposited on the entire surface of the insulating 
layer 1. By the mask patterning process, the aluminum layer 2 is etched to 
provide a plurality of aluminum wired layers 2AA, with each aluminum wired 
layer 2A being spaced apart relative to each other and having a top 2B and 
side walls 2C, on the insulating layer 1. A titanium layer 3 is then 
deposited on the entire surface of the structure as illustrated at FIG. 
2A. The titanium layer 3 described in connection with FIG. 2A is heated in 
a furnace, not shown, at a temperature of 400-500 degree Celsius 
simultaneously with application of conditioning gases, such as for 
example, a nitrogen-hydrogen gas mixture, nitrogen gas or argon gas. This 
causes the titanium in the titanium layer 3 to react with the aluminum in 
the each aluminum wired layer 2A, of the plurality of aluminum wired 
layers 2AA, to form a first Al-Ti compound metal layer 4A on each aluminum 
wired layer 2A of the plurality of aluminum wired layers 2AA. As 
illustrated at FIG. 2B, layer 4A covers the top 2B and side walls 2C of 
each aluminum wired layer 2A. The portion of the titanium layer 3 which 
was deposited on the insulating layer 1 exposed in the preparation of the 
plurality of aluminum wired layers 2AA, remains, as illustrated at FIG. 
2B. 
In order to selectively remove that portion of the titanium layer 3 which 
remains on the insulating layer 1, an etching process is performed on the 
resultant structure of FIG. 2B, utilizing an etchant of NH.sub.4 
OH/H.sub.2 O.sub.2 /H.sub.2 O (composite rate, 1:1:5) which is at a 
temperature of 18-40 degree Celsius. This results in the top 2B and side 
walls 2C of each aluminum wired layer 2A being coated with the first Al-Ti 
compound metal layer 4A and the insulating layer 1 being exposed where the 
titanium layer 3 has been etched away, as illustrated at FIG. 2C. 
FIGS. 3A through 3D are sectional views of a partially completed aluminum 
wired layer utilizing the process steps according to a second embodiment 
of the present invention for manufacturing an aluminum wired layer on an 
insulating layer 1. The aluminum wired layer produced by the second 
embodiment of present invention effectively restrains electromigration 
phenomenon as well as hillock formation in the aluminum wired layer as 
compared to the prior art aluminum wired layer described in the opening 
paragraph. 
To form a plurality of aluminum wired layers 2AA, a first titanium layer 3A 
and an aluminum layer 2 are sequentially deposited over the insulating 
layer 1. By the mask patterning process, the aluminum layer 2 and the 
first titanium layer 3A are etched to provide a plurality of aluminum 
wired layers 2AA, with each aluminum wired layer 2A being spaced apart 
relative to each other and having a top 2B and side walls 2C, on the 
insulating layer 1 as illustrated at FIG. 3A. 
FIG. 3B illustrates a second titanium layer 3B deposited on the entire 
surface of the structure described in connection with FIG. 3A. 
The first 3A and second 3B titanium layers are heated in a furnace, not 
shown, at a temperature of 400-500 degree Celsius simultaneously with 
application of conditioning gases, such as for example, a 
nitrogen-hydrogen gas mixture, nitrogen gas or argon gas, to cause the 
titanium in the first 3A and second 3B titanium layers to react with 
aluminum 2 in the each aluminum wired layer 2A of the plurality of 
aluminum wired layers 2AA. 
First and second Al-Ti compound metal layers 4A, 4B are thus formed on each 
aluminum wired layer 2A of the plurality of aluminum wired layers 2AA, 
i.e. layers 4A, 4B cover the top 2B and side walls 2C and the bottom 2D of 
each aluminum wired layer 2A. The titanium layer 3B which was deposited on 
the exposed portion of the insulating layer 1, remains, as illustrated at 
FIG. 3C. 
In order to selectively remove the second titanium layer 3B which remains 
on the insulating layer 1, an etching process is performed on the 
resultant structure of FIG. 3C, utilizing an etchant of NH.sub.4 
OH/H.sub.2 O.sub.2 /H.sub.2 O (composite rate, 1:1:5) which is at a 
temperature of 18-40 degree Celsius. This results in the top 2B, bottom 2D 
and side walls 2C of each aluminum wired layer 2A being coated with the 
first and second Al-Ti compound metal layers 4A, 4B and the insulating 
layer 1 being exposed where the second titanium layer 3B was etched away, 
as illustrated at FIG. 3D. 
FIGS. 4A through 4C are sectional views of partially completed aluminum 
wired layer utilizing the process steps for manufacturing the aluminum 
wired layer on a silicon substrate 10 according to a third embodiment of 
the present invention. FIGS. 2A through 2C and FIGS. 3A through 3D, above, 
describe forming aluminum wired layers on an insulating layer. 
The third embodiment of the present invention provides a structure having a 
metal barrier layer 5A, such as for example, TiW, formed at the bottom 2D 
of each aluminum wired layers 2A where the aluminum wired layer 2A is 
formed on the silicon substrate and having a first Al-Ti compound metal 
layer 4 formed on the top 2B and side walls 2C of each aluminum wired 
layer 2A. The reason why the metal barrier layer 5 is formed at the bottom 
2D of each aluminum wired layer 2A of the third embodiment is to solve the 
draw back of the previously mentioned prior art aluminum wired layers 2A 
by preventing the occurrence of the formation of a pit at the junction 
between the silicon substrate and the each aluminum wired layers during 
heat treatment. 
To form a plurality of aluminum wired layers 2AA, a metal layer 5, such as 
for example, TiW, and a aluminum layer 2 are sequentially deposited over 
the silicon substrate 10. By the mask patterning process, the aluminum 
layer 2 and the metal layer 5 are etched to provide a plurality of 
aluminum wired layers 2AA, with each aluminum wired layer 2A being spaced 
apart relative to each other and having a top 2B, bottom 2D and side walls 
2C, and to provide a metal barrier layer 5A formed at the bottom 2D of the 
each aluminum wired layer 2A as illustrated at FIG. 4A. 
FIG. 4B illustrates a titanium layer 3 deposited on the entire surface of 
the structure described in connection with FIG. 4A. 
The titanium layer 3 is heated in a furnace, not shown, at a temperature of 
400-500 degree Celsius simultaneously with application of conditioning 
gases, such as for example, a nitrogen-hydrogen gas mixture, nitrogen gas 
or argon gas, to cause the titanium in the titanium layer 3 to react with 
aluminum in the each aluminum wired layer 2A of the plurality of aluminum 
wired layers 2AA. A first Al-Ti compound metal layers 4A is thus formed on 
each aluminum wired layer 2A of the plurality of aluminum wired layers 
2AA, i.e. layer 4A covers the top 2B and side walls 2C of each aluminum 
wired layer 2A, and the metal barrier layer 5A is also formed at the each 
aluminum wired layer 2A of the plurality of aluminum wired layers 2AA. The 
titanium layer 3 which was deposited on the exposed portion of the silicon 
substrate 10, remains, as illustrated at FIG. 4B. 
In order to selectively remove the titanium layer 3 which remains on the 
silicon substrate 10, an etching process is performed on the resultant 
structure of FIG. 4B, utilizing an etchant of NH.sub.4 OH/H.sub.2 O.sub.2 
/H.sub.2 O (composite rate, 1:1:5) which is at a temperature of 18-40 
degree Celsius. This results in the top 2B and side walls 2C of each 
aluminum wired layer 2A the bottom 2D of each formed with the metal 
barrier layer 5A being coated with the first Al-Ti compound metal layers 
4A and with the silicon substrate being exposed where the titanium layer 3 
was etched away, as illustrated at FIG. 4C. 
The fourth embodiment of the present invention provides a structure having 
an Al-Ti compound metal layer 5A and a metal barrier layer 5, such as, for 
example TiW, sequentially formed at the bottom 2D of each aluminum wired 
layers 2A where the aluminum wired layer 2A is formed on the silicon 
substrate and having a first and second Al-Ti compound metal layer 4A, 4B 
formed on the top 2B and both side walls 2C of each aluminum wired layer 
2A. 
FIGS. 5A through 5C are sectional views of a partially completed aluminum 
wired layer utilizing the process steps according to a fourth embodiment 
of the present invention for manufacturing a aluminum wired layer on a 
silicon substrate 10. The aluminum wired layer produced by the second 
embodiment of present invention effectively restrains previously mentioned 
electromigration phenomenon and hillock formation in the aluminum wired 
layer as compared to the prior art aluminum wired layer described in the 
opening paragraph. 
To form a plurality of aluminum wired layers 2AA, a metal layer 5, a first 
titanium layer 3A and an aluminum layer 2 are sequentially deposited over 
the silicon substrate 10. By the mask patterning process, the aluminum 
layer 2, the first titanium layer 3A and the metal layer 5 are etched to 
provide a plurality of aluminum wired layers 2AA, with each aluminum wired 
layer 2A being spaced apart relative to each other and having a top 2B, 
bottom 2D and both side walls 2C of the each aluminum wired layer 2A, and 
to provide a metal barrier layer 5A formed at the bottom 2D of the each 
aluminum wired layer 2A as illustrated at FIG. 5A. 
FIG. 5B illustrates a second titanium layer 3B deposited on the entire 
surface of the structure described in connection with FIG. 5A. 
The first 3A and second 3B titanium layers are heated in a furnace, not 
shown, at a temperature of 400-500 degree Celsius simultaneously with 
application of conditioning gases, such as for example, a 
nitrogen-hydrogen gas mixture, nitrogen gas or argon gas, to cause the 
titanium in the first 3A and second 3B titanium layers to react with 
aluminum 2 in the each aluminum wired layer 2A of the plurality of 
aluminum wired layers 2AA. First and second Al-Ti compound metal layers 
4A, 4B are thus formed on each aluminum wired layer 2A of the plurality of 
aluminum wired layers 2AA, and on each metal barrier layer 5A, 
respectively, i.e. layers 4A, 4B cover the top 2B and side walls 2C and 
the bottom 2D of each aluminum wired layer 2A, and also cover the metal 
barrier layer 5A positioned between the silicon substrate 10 and the Al-Ti 
compound metal layer 4B formed at the bottom 2D of each aluminum wired 
layer 2A. The titanium layer 3B which was deposited on the exposed portion 
of the silicon substrate 10, remains, as illustrated at FIG. 3C. 
In order to selectively remove the second titanium layer 3B which remains 
on the silicon substrate 10, an etching process is performed on the 
resultant structure of FIG. 3C, utilizing an etchant of NH.sub.4 
OH/H.sub.2 O.sub.2 /H.sub.2 O (composite rate, 1:1:5) which is at a 
temperature of 18-40 degree Celsius. This results in the top 2B, bottom 2D 
and side walls 2C of each aluminum wired layer 2A being coated with the 
Al-Ti compound metal layers 4A, 4B and the silicon substrate 10 being 
exposed where the second titanium layer 3B was etched away, as illustrated 
at FIG. 5C. 
As described above, with the improvement of a aluminum wired layer for 
connecting device to device in semiconductor device according to the 
present invention, it is possible to prevent hillock formation at the top 
and side walls of the aluminum wired layer, and to prevent the 
electromigration phenomenon in the aluminum wired layer, thereby reducing 
the deterioration of the desireable properties of the semiconductor 
device. 
The foregoing description of the preferred embodiment has been presented 
for the purpose of illustration and description. It is not intended to 
limit the scope of this invention. Many modifications and variations are 
possible in the light of the above teaching. It is intended that the scope 
of the invention be defined by the claims.