JP2626927C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a case where each layer of a multilayer aluminum wiring layer is connected.
The present invention relates to a semiconductor device connected through a hole. [Prior Art] In a semiconductor device, an element such as a transistor (element) is usually provided on a semiconductor substrate.
Is formed. Electrical connection between these elements and external circuits
Various wirings are formed on a semiconductor substrate for connection. Conventionally, these wiring
As polycrystalline silicon film, refractory metal film, refractory metal silicide film, aluminum
Nitride films and aluminum alloy films have been used. Recently, high speed is required
In a highly integrated semiconductor device, it is necessary to reduce wiring resistance
. Therefore, it is formed by aluminum film or aluminum alloy film with low specific resistance
Aluminum multilayer wiring structure has become an essential wiring structure in semiconductor devices
I have. FIG. 6 is a cross section showing a semiconductor device having a conventional aluminum multilayer wiring structure.
FIG. Referring to FIG. 6, a DRAM (Dyna) is provided on silicon semiconductor substrate 1.
Mic Random Access Memory) Cell 2 is a stacked cell
It is formed so as to have a metal structure. Under this DRAM cell 2, a base insulating
The film 3 is formed. On the base insulating film 3, at a predetermined interval from each other
A first aluminum wiring layer 4 is formed. Covers first aluminum wiring layer 4
Thus, interlayer insulating film 5 is formed. The interlayer insulating film 5 has a connection hole (via
Hole (via-hole) or through-hole (through-hol)
e) 6). The second aluminum wiring layer 7 is an interlayer insulating
Formed on the film 5 and connected to the first aluminum wiring layer 4 through the connection hole 6
I have. The DRAM cell 2, the first aluminum wiring layer 4, and the second aluminum
Protective insulating film for covering the metal wiring layer 7 and protecting it from moisture invading from the outside.
8 are formed. In the conventional aluminum multilayer wiring structure as shown in FIG.
A connection between the aluminum wiring layer 4 and the second aluminum wiring layer 7 (hereinafter referred to as a via
(Referred to as the hole portion), the technical level of the yield and reliability of semiconductor devices
Depends. Hereinafter, a method of manufacturing the conventional aluminum multilayer wiring structure shown in FIG.
In particular, the description will focus on the formation of a via hole. In addition, as a multilayer wiring structure
Generally, a combination of a polycrystalline silicon wiring, a high melting point metal wiring, a high melting point metal silicide wiring and an aluminum wiring is used. However, here, the first layer
Aluminum two-layer wiring in which both the wiring and the second layer wiring are aluminum wiring
The case of the structure will be described. 7A to 7G show a conventional semiconductor device having an aluminum multilayer wiring structure.
FIG. 5 is a cross-sectional view for explaining a manufacturing process of the device. See FIGS. 7A to 7G.
Next, the manufacturing process will be described. First, referring to FIG. 7A, a DRAM cell 2 is formed on a surface of a silicon semiconductor substrate 1.
It is formed. The DRAM cell 2 includes an oxide film 301 for element isolation,
-Gate electrode 302, impurity diffusion layer 303, word line 304, storage node 305
, A capacitor insulating film 306, a cell plate 307 and an insulating film 309.
Have been. Referring to FIG. 7B, the silicon semiconductor substrate on which DRAM cell 2 is formed is shown.
A base insulating film 3 is formed on the entire surface of the plate 1. After that, photoengraving technology and etching
A contact hole 308 is formed in a predetermined portion of the base insulating film 3 using a technique. This
To electrically contact the impurity diffusion layer 303 through the contact hole 308 of FIG.
First aluminum wiring layer 4 is formed as a bit line. Recently, submicron
-For semiconductor devices in which the size of each element is miniaturized to the order,
As the aluminum wiring layer 4, titanium nitride (TiN) or titanium / tungsten (
Barrier metal film 310 such as TiW) and aluminum such as Al-Si-Cu
A wiring layer having a structure in which the alloy films 311 are combined is used. Al with such a structure
The minium wiring layer is used for the following reasons. That is, in the contact portion, the aluminum and silicon substrates (impurity diffusion)
Layer), an abnormal reaction (alloy spike) occurs locally. this
As a result, the reaction layer penetrates the region of the impurity diffusion layer and
Extend. As a result, a junction leak of the impurity diffusion layer occurs. To prevent this
A barrier metal film is formed so as to be in direct contact with the silicon substrate (impurity diffusion layer).
It is. Silicon film in aluminum alloy film is contoured by solid phase epitaxial growth.
Precipitates at the contact area. As a result, a contact failure occurs. To prevent this,
A barrier metal film is formed below the aluminum alloy film. An interlayer insulating film and a protective insulating film are formed on the aluminum wiring layer. This
The aluminum wiring is disconnected due to the film stress of these upper insulating films. like this
Barrier metal film to increase resistance to stress migration phenomenon
Is formed under the aluminum alloy film. The film constituting the first aluminum wiring layer 4 is usually formed by a sputtering method.
, Formed by patterning using photoengraving technology and etching technology
It is. Referring to FIG. 7C, an interlayer insulating film 5 is formed over the entire surface of first aluminum wiring layer 4.
Is done. This interlayer insulating film 5 is formed, for example, by a chemical vapor deposition method (CVD: Chemi).
silicon oxide film formed by cal vapor deposition
321, an inorganic coating insulating film 322, and a silicon oxide film formed by a CVD method
323 is an insulating film combined. The silicon oxide film 321 is usually made of silane (SiH _Four ) Gas and oxygen (O _Two ) There is gas
Or nitrous oxide (N _Two O) Formation at 300 to 450 ° C. using a mixed gas with gas
It is formed by a CVD method using heat or plasma at a temperature. Also recently,
TEOS (Tetra-
Using an organic silane-based material such as Ethyl-Ortho-Silicate)
Thus, a silicon oxide film is formed. The inorganic coating insulating film 322 formed for planarization is made of silanol (Si (OH
) _Four ) Or the like as a main component. The main component is silanol
After spin-coating the material, baking is performed at a temperature of 400 to 450 ° C.
The surface of the silicon oxide film 321 formed by the CVD method
Is flattened. Since the inorganic coating insulating film 322 has high hygroscopicity,
Exposure to the side wall of the hole causes adverse effects such as gas release. for that reason,
The surface of the inorganic coating insulating film 322 is not exposed on the side wall of the via hole.
Etch barrier using dry etching technology with fluorine gas or argon gas
A lock process is performed on the inorganic coating insulating film 322. On the inorganic coating insulating film 322, a method similar to the formation of the silicon oxide film 321 is used.
As a result, a silicon oxide film 323 is formed. Referring to FIG. 7D, a predetermined surface region of first aluminum wiring layer 4 is exposed.
As described above, the connection hole 6 is formed by using the photomechanical technology and the etching technology. This work
The process is performed as follows. That is, the region other than the region where the connection hole 6 is formed by using the photoengraving technique is formed in the foreground.
Covered with photoresist 324. After that, the interlayer insulating film 5 is
The connection hole 6 is opened by selective removal by an etching method.
. Note that the photoresist 324 and reaction products generated during etching are:
After etching, oxygen (O _Two ) Removed using plasma or wet chemical treatment. Referring to FIG. 7E, the first aluminum wiring layer 4 is
The surface is CHF _Three Exposed to fluorine gas or oxygen gas plasma
The surface of the first aluminum wiring layer 4 in the connection hole 6 is covered with aluminum
An altered layer 201 of aluminum (a layer containing a fluoride or an oxide) is formed. for that reason
, Remove the insulating film consisting of these thin aluminum alteration layers,
Before the second aluminum wiring layer is formed, argon ion
(Ar ⁺ ) 202 is performed. Referring to FIG. 7F, the second aluminum wiring layer 7 is continuously formed in a vacuum.
Is deposited using a sputtering method. As the second aluminum wiring layer 7, A
Aluminum alloy films such as l-Si, Al-Si-Cu, and Al-Cu are used.
You. Note that these films are made of a photolithography technique or a photolithography technique, like the first aluminum wiring layer 4.
It is formed by patterning using an etching technique. further,
The connection between the first aluminum wiring layer 4 and the second aluminum wiring layer 7 in the connection hole 6
After the second aluminum wiring layer 7 is formed,
Heat treatment is performed at a temperature of about 00 to 450 ° C. Finally, as shown in FIG. 7G, the water entering the semiconductor device and the wiring from the outside
Protection insulating film 8 such as a silicon oxide film or a silicon nitride film.
Is deposited on the second aluminum wiring layer 7 by using the CVD method. [Problems to be Solved by the Invention] FIGS. 8A, 8B, and 9 are cross-sectional views for explaining a problem of a conventional semiconductor device having an aluminum two-layer wiring structure. Problems of the conventional aluminum multilayer wiring structure will be described below. With the miniaturization of the wiring due to the integration of the semiconductor device, the diameter of the connection hole 6 becomes smaller.
When the diameter of the connection hole 6 reaches the submicron level, the voltage at the connection hole 6
There are problems with the stability and reliability of the connection. As described above, conventionally, before forming the second aluminum wiring layer 7, the argon
An on-sputtering / etching process is performed. This is shown in FIG. 8A.
Formed on the surface of first aluminum wiring layer 4 in connection hole 6
Transformed layer (layer containing fluoride or oxide) 201 of aluminum into argon ion 202
Therefore, it is to be removed. Aspect ratio of connection hole 6 (B / A) [A: diameter of connection hole
, B: the thickness of the interlayer insulating film (about 1 μm)] is less than 1
In this case, as shown in FIG.
The aluminum fluoride or oxide particles 203 that have been removed are sufficiently extended to the outside of the connection hole 6.
Scatter. Therefore, by removing the altered layer 201 of aluminum, contact is made.
The surface of the first aluminum wiring layer 4 in the connection hole 6 can be made a normal surface
Met. However, a submicron level contact having an aspect ratio (B / A) exceeding 1 is required.
In the continuous hole 6, as shown in FIG.
Some of the aluminum fluoride or oxide particles 203 that have been removed
And cannot scatter to the outside of the connection hole 6. Therefore, the connection hole 6
A phenomenon occurs in which some of the particles 204 are re-adhered to the inside of the substrate. As a result, the second aluminum wiring layer 7 was deposited continuously in a vacuum.
Even in such a case, as shown in FIG.
At the interface 205 between the first aluminum wiring layer 4 and the second aluminum wiring layer 7
Of aluminum fluoride and oxide re-adhered during sputtering and etching
Particles 204 will be present. Thereby, formation of the second aluminum wiring layer
In the subsequent heat treatment at about 400 to 450 ° C., the first aluminum wiring layer and the second aluminum
Mixing at the interface 205 with the luminium wiring layer is not sufficiently performed. As a result, an increase in contact resistance (hereinafter, referred to as a via-hole resistance) and an open defect (a first aluminum wiring layer and a second aluminum wiring
(A defect that the layer is not electrically connected). In addition, the initial via-hole resistance is obtained by the above-described heat treatment at 400 to 450 ° C.
Is normal, the first aluminum wiring layer 4 and the second aluminum wiring layer
The mixing at the interface 205 with No. 7 is not sufficiently performed. Therefore,
Connection holes such as Kutro migration resistance and stress migration resistance
6 has a problem that the reliability is deteriorated. Further, as the aspect ratio of the connection hole 6 increases, the second
2 The coverage (coverage rate) in the connection hole 6 of the aluminum wiring layer 7 is significantly reduced.
Inconvenience occurs. When coverage of aluminum in connection hole 6 is poor
Only the reliability of the connection hole 6 such as the resistance to electromigration deteriorates.
However, there is also a problem that the via-hole resistance increases. Such problems will be addressed in future submissions where the aspect ratio (B / A) will become even larger.
Semiconductor device miniaturized to Cron order, miniaturized to half micron order
This is a significant problem in the semiconductor device. The present invention has been made to solve the above-described problems, and has a lower layer
At the connection between the aluminum wiring layer and the upper aluminum, the lower aluminum
Promotes mixing at the interface between the wiring layer and the upper aluminum wiring layer, and further connects
By improving the coverage in the hole, you can obtain a stable via hole resistance,
Electromigration tolerance and stress
High-quality, high-yield semiconductors with improved levels of reliability, such as the tolerance for migration
It is intended to provide a device. [Means for Solving the Problems] A semiconductor device according to the present invention includes a semiconductor substrate and a first aluminum containing silicon.
A second wiring layer, an insulating layer, and a second aluminum wiring layer. The first al
The minium wiring layer is formed on the main surface of the semiconductor substrate. The insulating layer comprises a first
It is formed on the aluminum wiring layer and reaches the surface of the first aluminum wiring layer.
It has a through hole. The second aluminum wiring layer is formed on the insulating layer and penetrated.
It is electrically connected to the first aluminum wiring layer through the hole. The second aluminum wiring layer includes a titanium layer, a titanium compound layer, a buried conductive layer,
Containing layer. The titanium layer has a thickness of 50 to 150 mm and has a through hole.
Formed on the insulating layer so as to be in contact with the surface of the first aluminum wiring layer.
I have. The titanium compound layer is formed on the titanium layer. Embedded conductive layer
The through hole is formed on the titanium compound layer in the hole. Alminium
The memory-containing layer is formed on the titanium compound layer and the buried conductive layer. Also,
The surface of the first aluminum wiring layer in contact with the titanium layer has titanium and aluminum
React with each other to form an intermetallic compound. [Operation] In the semiconductor device according to the present invention, the lower first aluminum layer is formed at the portion of the through hole.
A titanium layer as an underlay film of an upper second aluminum wiring layer in contact with the wiring layer;
And a titanium compound layer. Lower first aluminum
The titanium layer contacts the surface of the memory wiring layer. This titanium layer bonds with fluorine and oxygen.
Since the resultant force is strong, the surface of the lower first aluminum wiring layer is
Aluminum fluoride and oxide particles due to redeposition during etching
Even if it remains, it plays the following role. That is, the titanium layer is made of aluminum fluoride or oxide particles.
Takes in as fluorides and oxides and decomposes. The titanium layer reacts with the underlying first aluminum wiring layer to form an intermetallic compound.
Object (TiAl _Three ) To form a first aluminum wiring layer and a second aluminum wiring layer.
The interface with the metal wiring layer is sufficiently reacted. On the other hand, the titanium compound layer formed on the titanium layer has a lower first aluminum layer.
Prevents the titanium layer in contact with the wiring layer from reacting first with the upper aluminum-containing layer.
So that the titanium layer reacts preferentially with the underlying first aluminum wiring layer.
To use. That is, when the titanium compound layer is not formed, the titanium layer and the upper aluminum layer are formed.
There is no layer at the interface with the metal-containing layer that hinders the reaction between the two. Therefore, titanium
The layer first contains the upper aluminum layer before reacting with the lower first aluminum wiring layer.
Easily reacts with the layer at a relatively low temperature of about 200 to 300 ° C., and forms an intermetallic compound (TiAl _Three ) Is formed. In this case, the titanium layer is a lower layer at the connection hole.
Remove any aluminum fluoride or oxide remaining on the surface of the first aluminum wiring layer.
Reacts with the underlying first aluminum wiring layer to form an intermetallic compound.
Absent. In contrast, a titanium compound with low reactivity with aluminum is placed on the titanium layer.
When the layer is provided, the reaction between the titanium layer and the upper aluminum-containing layer is suppressed. So
Therefore, after forming an upper aluminum-containing layer, heat treatment is performed at 300 to 450 ° C.
As a result, the surface of the underlying first aluminum wiring layer is left at the connection hole.
Fluoride and oxide of existing aluminum (re-adhesion during sputter etching process)
Is taken in as a fluoride or oxide of titanium and decomposed. Also
, The titanium layer reacts with the underlying first aluminum wiring layer to form an intermetallic compound (TiA).
l _Three ) Is formed, and the titanium compound layer forms an interface between the titanium layer and the first aluminum wiring layer.
Plays a role in sufficiently reacting. On the other hand, tungsten or tungsten formed on the titanium compound layer at the connection hole
The aspect ratio of the connection hole is significantly improved by the embedded plug of the ten compound. In this way, even in connection holes having a submicron level diameter,
The typical contact resistance (via-hole resistance) becomes stable. In addition,
Via holes such as migration tolerance and stress migration tolerance
The level of reliability in the department is also improved. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a semiconductor device according to one embodiment of the present invention. Fig. 1
Referring to, DRAM cell 2 is formed on silicon semiconductor substrate 1
. On this DRAM cell 2, a base insulating film 3 is formed. Base insulating film 3
A first aluminum wiring layer 4 is formed on the first aluminum wiring layer at an interval. Ma
An interlayer insulating film 5 is formed so as to cover the first aluminum wiring layer 4. Between layers
The insulating film 5 has a connection opened to reach the surface of the first aluminum wiring layer 4.
A hole 6 is formed. The first aluminum wiring layer 4 is electrically connected to the
A second aluminum wiring layer 100 is formed on interlayer insulating film 5 so as to be electrically connected. The second aluminum wiring layer 100 includes a titanium film 101 and titanium nitride.
Film 102, tungsten plug 103, aluminum film or aluminum alloy
And a film 104. The titanium film 101 is formed as a base film of the second aluminum wiring layer 100,
Contact with the surface of first aluminum wiring layer 4. The titanium nitride film 102 is made of the second aluminum
It is formed as a base film of Ni 100 and is formed on the titanium film 101. Tan
Gusten plug 103 is formed on titanium nitride film 102 and buried in connection hole 6.
It is formed to be embedded. Aluminum film or aluminum alloy film 104
Is formed on the titanium nitride film 102 and the tungsten plug 103. this
In order to protect the wiring structure from the external environment, a protective insulating film 8 is formed on the entire surface.
. The interface between the titanium film 101 and the first aluminum wiring layer 4 is caused by the reaction between the titanium film 101 and the first aluminum wiring layer 4.
To the intermetallic compound (TiAl _Three ) Layer 206 is formed. Next, in the semiconductor device shown in FIG.
Of the connection portion (via hole portion) between the layer 4 and the upper second aluminum wiring layer 100
The manufacturing process will be described. 2A to 2H show the half shown in FIG.
Sectional drawing for explaining the manufacturing process of the aluminum wiring structure in the conductor device
It is. Incidentally, in the prior art, the product described with reference to FIGS. 7A to 7D is used.
Since the manufacturing process is the same as the manufacturing process of the present invention, the description is omitted. Referring to FIG. 2A, during the manufacturing process of connection hole 6, CHF _Three Such as fluorine
The first aluminum in the connection hole 6 is exposed to the plasma of the gas or the oxygen gas.
On the surface of the wiring layer 4, an altered layer of aluminum (fluorinated) having a thickness of about 100 °
Layer 201 containing a substance or an oxide). Remove this thin layer 201
First, in order to obtain a stable via hole resistance,
A sputter etching process is performed. Referring to FIG. 2B, the submicron level having an aspect ratio (B / A) exceeding 1 is referred to.
In the case of the metal connection hole 6, the sputtering / etching process using argon ions 202 is performed.
In theory alone, as mentioned above, aluminum sputtered by argon ions
Fluoride or oxide particles are re-adhered. Therefore, on the surface 205 of the first aluminum wiring layer 4 in the connection hole 6, aluminum fluoride or oxide
Particles 204 remain. Referring to FIG. 2C, most of the altered layer 201 of aluminum is sputter-etched.
After the removal by the chilling process, a small grain of the altered layer of aluminum remained
In order to disassemble the element 204, the titanium film 101 is continuously
It is deposited over the entire surface with a thickness of about 50 to 150 °. Next, referring to FIG. 2D, a titanium nitride film 102 is
It is deposited with a thickness of about 0 to 1000 °. This deposition method usually includes Ti
Ar + N _Two Reactive sputtering method for sputtering in gas atmosphere
Is used. This titanium nitride film 102 has a first aluminum
The titanium film 101 that is in contact with the minium wiring layer 4 is opposite to the upper aluminum-containing layer first.
Responsible for responding. For this reason, the upper aluminum-containing layer
Low reactivity and minimize increase in via hole resistance
Used is a titanium nitride film having a small specific resistance of about 250 to 400 μΩ · cm.
. Usually, it is used as a barrier metal film in the contact part with the silicon substrate.
Titanium nitride films must have barrier properties against silicon and aluminum.
Therefore, a film having a high specific resistance of about 400 to 2000 μΩ · cm is used. Only
However, when such a titanium nitride film is used in the via hole, the via hole
There is a problem that the resistance is several times higher than the conventional structure. by
As described above, the titanium nitride film 102 used in the
1 is formed for the purpose of suppressing the reaction between the upper layer and the aluminum-containing layer.
. For this reason, the titanium nitride film 102 needs a high barrier property against aluminum.
And not. From this, nitriding with a small specific resistance of about 250 to 400 μΩ · cm
A titanium film can be used. As a result, the via-hole resistance also increases.
The level can be reduced to a practically acceptable level of 50% or less. The thickness of the titanium nitride film 102 is such that the lower titanium film 101 is an upper aluminum film.
Reaction with the aluminum-containing layer and increase the via hole resistance.
The reason is that it is about 500 to 1000 ° for the reason that it is suppressed to a level having no practical problem. Thereafter, referring to FIG. 2E, CVD is performed in an atmosphere of 300 to 500 ° C.
A tungsten film is formed on the entire surface by the method. The following equations (1) and (2) are used for the CVD method.
The formation process of a typical tungsten film is shown by a chemical formula. [SiH _Four Reduction method] 2WF ₆ + 3SiH _Four → 2W + 3SiH _Four ↑ + 6H _Two ↑ (1) [Si _Two Reduction method] WF ₆ + 3H _Two → W + 6HF (2) The feature of the tungsten film forming method by the CVD method is that
The covering property is extremely good. For this reason, connection with a small diameter and a large aspect ratio
The hole 6 is completely filled with the tungsten film 103. Next, referring to FIG. 2F, SF ₆ Formed by the CVD method
The entire surface of the tungsten film 103 is etched back. Then, it is embedded in the connection hole 6.
The remaining tungsten film is removed except for the inserted tungsten plug 103.
You. Thereafter, referring to FIG. 2G, as the uppermost layer of second aluminum wiring layer 100,
For example, an aluminum alloy film 104 such as an Al—Si—Cu film is continuously formed.
It is deposited by a sputtering method. Next, a titanium film 101, a titanium nitride film 102, a tongue
The second electrode having a four-layer structure including a stainless plug 103 and an aluminum alloy film 104 is used.
In the same manner as the first aluminum wiring layer 4, the luminium wiring layer 100
It is patterned using a technique or an etching technique. Further, referring to FIG. 2G, the first aluminum wiring layer 4 and the second aluminum
300 to 450 ° C. to promote mixing of the interface with the wiring layer 100
At a temperature of about 15 to 60 minutes. As a result, the buyer hall
Of aluminum remaining on surface 205 of first aluminum wiring layer 4 in
Fluoride or oxide particles 204 are decomposed by the action of the titanium film 101.
Further, the first aluminum wiring layer 4 and the titanium film 101 react with each other to form an intermetallic compound (
TiAl _Three ) Layer 206 is formed. FIGS. 3A and 3B are base films of the second aluminum wiring layer in the present invention.
FIG. 4 is a schematic diagram for explaining the function of a laminated film composed of a certain titanium film, a titanium compound film, and tungsten. Here, FIGS. 3A and 3B show the first aluminum wiring layer 4 and the second aluminum wiring layer.
In order to explain the mixing action of the interface with the minium wiring layer 100,
The connection structure is shown enlarged. Referring to FIG. 3A, a sputter etching process is performed.
Due to the reattachment of aluminum fluoride and oxide particles during processing,
The particles 204 of the altered layer of aluminum are formed on the surface 205 of the
It remains even after the formation of the luminium wiring layer 100. These particles 204
Interface 205 between first aluminum wiring layer 4 and second aluminum wiring layer 100
The mixing action in Therefore, as shown in FIG. 3B, a second aluminum wiring layer 100 is formed.
After that, heat treatment is performed at a temperature of 300 to 450 ° C. for about 15 to 60 minutes as described above.
Is done. Thus, the particles 204 of the altered layer of aluminum are made of titanium oxide or
It is taken in as fluoride and decomposed. This is because the titanium film 101 is made of aluminum
Strong binding force with fluorine and oxygen that constitute the altered substance of the
This is because a fluoride or an oxide of titanium is easily formed by the heat treatment. In addition,
Reacts with the first aluminum wiring layer 4 and the titanium film 101 to form an intermetallic
Compound (TiAl _Three ) Layer 206 is formed. Thereby, at this interface 205
The mixing action is promoted. Finally, referring to FIG. 2H, a semiconductor element and a wiring formed on the semiconductor substrate are removed.
Silicon oxide film or silicon nitride to protect it from moisture
A protective insulating film 8 such as a passivation film is formed on the second aluminum wiring layer 100 by using a CVD method.
Deposited. FIG. 4 is a schematic diagram for explaining that an optimum value of the titanium film thickness exists.
. Note that the thickness of the titanium film 101 used in the wiring connection structure of the present invention is
Since the optimum value exists for the following reason, the description will be made with reference to FIG. After the second aluminum wiring layer 100 is formed, heat treatment is performed at 300 to 450 ° C.
Therefore, the titanium film 101 reacts with the first aluminum wiring layer 4 to form an intermetallic compound (
TiAl _Three ) The layer 206 is formed. At the same time, the titanium film 101 also reacts with silicon 207 contained in the first aluminum wiring layer 4 by about 1 to 2% by weight,
TiSi _Two 208 are also formed. Silicon in the first aluminum wiring layer 4
Is added to prevent junction leakage at the contact portion 308 with the silicon substrate.
Has been added. That is, it is used as a barrier metal film of the first aluminum wiring layer 4.
Titanium nitride film 310 having a high specific resistance (about 400 to 2000 μΩ · cm)
Is not perfect barrier to silicon and aluminum
Because. A film of a titanium film 101 used as a base film of the second aluminum wiring layer 100
If the thickness is too large, the silicon concentration in the first aluminum wiring layer 4 will decrease.
Thus, a junction leak occurs in the contact portion 308. On the other hand, titanium film 1
01 is too small, as will be explained with reference to FIGS. 3A and 3B.
In addition, it promotes decomposition of aluminum fluoride and oxide particles and promotes mixing at the interface.
The effect of progress is not enough. For the above reasons, the titanium film 101 used in the wiring connection structure of the present invention is
The film thickness has upper and lower limits. Based on the knowledge obtained by experiments by the present inventors and others
In this case, it is desired that the thickness of titanium film 101 be in the range of 50 ° or more and 150 ° or less.
Good. In the above embodiment, the aluminum alloy forming the second aluminum wiring layer is formed.
In order to suppress the reaction between the gold film 103 and the titanium film 101,
The case where the titanium nitride film 102 is provided is described. However, both
Other films such as a titanium oxide film and a titanium oxynitride film that
The same effect can be obtained with a tan compound film. All of these films were
It can be deposited using a reactive sputtering method as in the example. In other words, titanium oxide
Ar + O _Two Deposit titanium oxynitride film in gas atmosphere
Ar + O _Two + N _Two Using Ti as a target in a gas atmosphere
Then, a desired titanium compound film can be deposited by sputtering. In this embodiment, the aluminum coverage of the via hole is improved.
For this reason, an example in which the tungsten plug 103 is formed by the CVD method has been described.
The present invention is not limited to this, and other metal CVD methods using tungsten silicide, molybdenum, aluminum, etc., other than tungsten, can provide the same effect.
. Further, in this embodiment, the aluminum two-layer wiring structure has been described.
The same effect can be obtained when applied to a semiconductor device having the above aluminum multilayer wiring structure.
I do. In this embodiment, a semiconductor device in which DRAM cells are formed on the surface of a semiconductor substrate is described.
Although an example in which the present invention is applied to a device is shown, the present invention is not limited to this, and other devices may be formed.
The same effect can be obtained by applying the present invention to a semiconductor device that has been manufactured. For example, an SRAM (Static Random Ac) is provided on the surface of a semiconductor substrate.
access memory) according to the present invention.
FIG. 5 shows an embodiment to which the minium multilayer wiring structure is applied. SRAM cell
A detailed description of the structure of a semiconductor device having a semiconductor device is omitted, and only the main structure is described.
I just stay. With reference to FIG. 5, a double-well CMOS (
Complementary Metal Oxide Semi-Condu
An SRAM cell 410 having a (ctor) structure is formed. Silicon semiconductor
On the substrate 1, a p-type well region 411 and an n-type well region 412 are formed adjacent to each other.
Have been. To electrically isolate these well regions 411 and 412,
Oxide films 413 for element isolation are formed on silicon semiconductor substrate 1 at intervals.
I have. In the p-type well region 411, the n-type impurity diffusion layer 415 is spaced apart from each other.
Are formed, and a gate electrode 414 is formed between them. In addition, n-type wafer
A p-type impurity diffusion layer 416 is formed in the metal region 412 at an interval from each other.
A gate electrode 414 is formed between them. So as to cover the gate electrode 414
And an insulating film 409 are formed. On the insulating film 409, polycrystalline silicon
The wiring layers 417 are formed at intervals. Below the SRAM cell 410,
A ground insulating film 3 is deposited. The base insulating film 3 and the insulating film 409 have an n-type
Contact hole 4 reaching the surface of impurity diffusion layer 415 or p-type impurity diffusion layer 416
18 are formed. Via this contact hole 418, the impurity diffusion layer 415
Alternatively, the first aluminum wiring layer 4 is formed on the base insulating film 3 so as to contact with the base insulating film 3. First aluminum wiring layer 4 and second aluminum wiring layer 1
The connection structure with 00 is the same as the structure shown in FIG. Similarly, an element formed on the surface of the silicon semiconductor substrate 1 is a DRAM cell or an S cell.
Other elements than the RAM cell, for example, an EPROM (Erasable Pro
Gramable Read Only Memory) cell, E ^Two PROM (E
electrical Erasable Programmable ROM)
Devices, micro-computer circuit elements, bipolar transistor elements, etc.
An element having another structure may be used. [Effects of the Invention] As described above, according to the present invention, the lower first aluminum wiring layer and the connection hole
And a titanium film as an underlay film of an upper second aluminum wiring layer in contact with the
Using a laminated structure film consisting of a tan compound layer and the product formed in the connection hole
A buried conductive layer is formed on the layer structure film so as to be buried, and is in contact with the titanium layer
Titanium and aluminum are formed on the surface of the first aluminum wiring layer by reaction
Forming the intermetallic compound, the connection hole of the multilayer aluminum wiring structure
A stable contact can be obtained in the part. Therefore, the electrical contour
Stability and the junction leakage can be prevented.
Semiconductor device at the connection hole such as
The reliability level of the device can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a semiconductor device according to an embodiment of the present invention, and FIGS. 2A to 2H are diagrams showing a two-layer aluminum wiring structure in the semiconductor device shown in FIG. FIGS. 3A and 3B are cross-sectional views for explaining the manufacturing process, and FIG. 3A and FIG. 3B illustrate the operation of a laminated structure film composed of a titanium film, a titanium compound film, and a tungsten plug which is a base film of the second aluminum wiring layer in the present invention. FIG. 4 is a schematic view for explaining that an optimum value of the titanium film thickness exists, FIG. 5 is a sectional view showing a semiconductor device according to another embodiment of the present invention, and FIG. Is a sectional view showing a semiconductor device having a conventional multilayer wiring structure, and FIGS. 7A to 7G are sectional views for explaining a manufacturing process of a semiconductor device having a conventional aluminum two-layer wiring structure; FIGS. FIGS. 8B and 9 are cross-sectional views for explaining the problems of the conventional semiconductor device having the aluminum two-layer wiring structure. In the drawing, 1 is a silicon semiconductor substrate, 3 is a base insulating film, 4 is a first aluminum wiring layer, 5 is an interlayer insulating film, 6 is a connection hole, 100 is a second aluminum wiring layer,
01 is a titanium film, 102 is a titanium nitride film, 103 is a tungsten plug, 104
Is an aluminum film or an aluminum alloy film. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

Claims: 1. A semiconductor device in which each layer of a multilayer aluminum wiring layer is connected through a connection hole, comprising: a semiconductor substrate having a main surface; and a first substrate formed on the main surface of the semiconductor substrate and containing silicon. An aluminum wiring layer; an insulating film formed on the first aluminum wiring layer and having a through hole reaching the surface of the first aluminum wiring layer; and an insulating film formed on the insulating layer and passing through the through hole. A second aluminum wiring layer electrically connected to the first aluminum wiring layer, wherein the second aluminum wiring layer is in contact with a surface of the first aluminum wiring layer through the through hole. wherein formed on the insulating layer, a titanium layer having a thickness of at least 150Å or less 50 Å, a titanium compound layer formed on the titanium layer, the transmural in A buried conductive layer formed to bury the through-hole on the titanium compound layer in the hole, and an aluminum-containing layer formed on the titanium compound layer and the buried conductive layer, wherein the titanium A semiconductor device, wherein an intermetallic compound formed by a reaction between titanium and aluminum is formed on a surface of the first aluminum wiring layer in contact with the layer.