JPH0729853A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide the manufacturing method, of a semiconductor device, wherein a rise in a contact resistance is suppressed and the generation of a junction leak is avoided in the manufacturing method, of the semiconductor device, wherein an interconnection formed on an interlayer insulating film is connected electrically to a diffused layer via a contact hole. CONSTITUTION:A contact hole 4 is formed in an interlayer insulating film 3, a Ti film 5 and a first TiN film 6 are formed on the whole face, and the TiN film is changed into a TiN film 6a by a nitrogen treatment. A second TiN film 7 and an Al alloy film 8a are formed inside the same vacuum chamber, and the Al alloy film 8a is made to reflow by a heat treatment and changed into an Al alloy film 8aa.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device for electrically connecting a wiring provided on an interlayer insulating film to a diffusion layer through a contact hole.

[0002]

2. Description of the Related Art In semiconductor devices which are highly integrated and multilayered, the demands for miniaturization and flattening of elements are becoming severe. It is becoming difficult for existing technology to satisfy the required performance also for connecting the wiring to the diffusion layer under the interlayer insulating film through the contact hole. In order to deal with this, as a contact hole burying method for the purpose of flattening the wiring on the contact hole, for example, a procedure guide-
Of-1991, BMC Conference-Pages 326-328 (Proceeding
of 1991 VMIC Conference p
p. 326-328), the Al reflow sputtering technique was developed. In this method, an Al film is deposited in a vacuum at room temperature and then heated at a high temperature in the same vacuum.
The membrane is fluidized.

Referring to FIG. 2, which is a sectional view of a main manufacturing process of a semiconductor device, the manufacturing method reported above (first conventional manufacturing method) is as follows. First, the interlayer insulating film 3 is formed on the surface of the silicon substrate 1 on which the diffusion layer 2 is formed. A contact hole 4 reaching the diffusion layer 2 is formed in the interlayer insulating film 3. Next, Al-Si-C (including the contact hole 4) covering the surface of the interlayer insulating film 3 is covered.
An Al alloy film 8b made of u is formed by sputtering in a vacuum chamber at room temperature [FIG. 2 (a)]. Next, in the same vacuum chamber, a temperature near the melting point of Al (400 ° C to 550 ° C)
C.) and the Al alloy film 8b is reflowed to become the Al alloy film 8ba [FIG. 2 (b)].

Further, another method for enhancing the reflowability of the Al alloy film to fill the contact hole is, for example, Proceedig-of-1992, BMC Conference, pp. 219-225 (Proceedi).
ng of 1992 VMIC Conference
e pp. 219-225).

Referring to FIG. 3, which is a sectional view of a main manufacturing process of a semiconductor device, the manufacturing method of this report (second conventional manufacturing method) is as follows. First, the contact hole 4 is formed in the same manner as the above-described first conventional manufacturing method until the contact hole 4 is formed of the interlayer insulating film 3 made of, for example, a PSG film. Next, the surface of the interlayer insulating film 3 (including the contact hole 4) is covered with the barrier metal film 9 deposited by sputtering in the vacuum chamber. Next, in the same vacuum chamber heated to about 500 ° C., A containing Al--Si
l alloy is sputtered, and the surface of the barrier metal film 9 is covered with an Al alloy film 8c (made of Al--Si). According to this method, the wettability of the Al alloy film 8c with respect to the barrier metal film 9 is high, and therefore this method is superior to the first manufacturing method in terms of burying the contact holes 4.

According to this report, the barrier metal film 9
A Ti film, a TiN film, or a TiON film has been tried as an example, but a void is generated in the TiON film. This is Al
This is because the wettability with the alloy film 8c is poor. Regarding the wettability, the Ti film is the most excellent. Since oxygen in the interlayer insulating film reacts with the Ti film to oxidize the surface of the Ti film, when the aspect ratio of the contact hole 4 becomes 1.3 or more, voids are generated in the contact hole 4. In this report, in order to avoid this, a spacer made of a silicon nitride film is provided on the side wall of the contact hole 4 (not shown in FIG. 3).

[0007]

Referring to FIG. 4, which is a cross-sectional view of a main manufacturing process of a semiconductor device, the first conventional method described above is referred to.
The above manufacturing method has the following problems. First, although depending on the aspect ratio of the contact hole 4, the Al alloy film 8b
A void 10 is formed in the contact hole 4 in the deposition step of [Fig. 4 (a)]. When the Al alloy film 8b is reflowed by high temperature heating to form the Al alloy film 8ba, even if the void 10 disappears, the spike 11 is formed by the abnormal diffusion of the Al alloy film 8b into the diffusion layer 2. [FIG.4 (b)]. The presence of the void 10 causes an increase in contact resistance, and the presence of the spike 11 causes a junction leak.

On the other hand, in the second conventional manufacturing method described above, the generation of voids is suppressed. However, referring to FIG. 5, which is a cross-sectional view of the main manufacturing process of the semiconductor device,
In the above-mentioned second conventional manufacturing method, the following problems remain. The barrier metal film 9 is a Ti film, a Ti6 film, or a Ti film.
Si in the Al alloy film 8c and Ti in the barrier metal film 9 at about 500 ° C.
The alloying reaction with is remarkable. As a result, the barrier metal film 9 does not function as a barrier, and
Similar to the manufacturing method of (1), it is impossible to suppress the generation of the spike 11a, and it is difficult to avoid the junction leak.

Even if the barrier metal film containing Ti is formed after the contact hole 4 is formed by applying the conventional second manufacturing method to the conventional first manufacturing method, spikes are generated.

An object of the present invention is to suppress an increase in contact resistance in a method of manufacturing a semiconductor device for electrically connecting a wiring provided on an interlayer insulating film to a diffusion layer through a contact hole, and to suppress a junction. It is an object of the present invention to provide a method for manufacturing a semiconductor device that avoids the occurrence of leakage.

[0011]

According to a method of manufacturing a semiconductor device of the present invention, an interlayer insulating film is deposited on a silicon substrate having a diffusion layer formed on a surface thereof, and a contact hole reaching the diffusion layer is formed in the interlayer insulating film. A step of sequentially forming a titanium film and a first titanium nitride film on the surface of the interlayer insulating film including the surface of the contact hole, a step of performing a nitrogen treatment, and a step of performing the first step in a vacuum chamber. A step of depositing a second titanium nitride film on the surface of the titanium nitride film; a step of depositing an aluminum alloy film containing at least silicon on the surface of the second titanium nitride film in the vacuum chamber; A step of fluidizing the alloy film and burying the contact holes with the aluminum alloy film; the aluminum alloy film, the second titanium nitride film, and the first titanium nitride. And a step of forming a wiring by sequentially patterning the titanium film.

Preferably, the deposition of the second titanium nitride film, the deposition of the aluminum alloy film and the fluidization of the aluminum alloy film are continuously performed in the same vacuum chamber. More preferably, the thickness of the second titanium nitride film is 0.02 μm to 0.1 μm. Still more preferably, the nitrogen treatment is lamp annealing in a nitrogen atmosphere of 400 ° C to 1000 ° C, furnace annealing in a nitrogen atmosphere of 400 ° C to 600 ° C, or nitrogen plasma treatment at 400 ° C to 800 ° C.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of the manufacturing process of the semiconductor device.
, One embodiment of the present invention is as follows. First, the interlayer insulating film 3 having a film thickness of about 1.0 μm is formed on the silicon substrate 1 having the diffusion layer 2 formed on the surface thereof. The contact hole 4 reaching the diffusion layer 2 is formed in the interlayer insulating film 3 by the known lithography technique and dry etching technique [FIG. 1 (a)].

Then, for example, by sputtering, a Ti film 5 having a film thickness of about 0.03 μm and a film thickness of 0.
A first TiN film 6 having a thickness of about 1 μm is sequentially deposited [FIG.
(B)]. The method for forming Ti5 and TiN film 6 is as follows.
It is not limited to sputtering, but may be CV, for example.
The method D may be used.

The amount of nitrogen in the first TiN film 6 at the film forming stage is stoichiometrically insufficient, and oxygen is adsorbed on the surface of the TiN film 6 and easily oxidized. Therefore, in particular, the barrier property of the TiN film 6 is improved (and the Ti film 5 is
Nitrogen treatment is performed to stabilize the contact resistance. By this nitrogen treatment, the first TiN film 6 is “nitrided”, the amount of nitrogen in the TiN film 6 is brought close to the stoichiometric amount, and the TiN film 6 becomes the TiN film 6a.
Further, this treatment also stabilizes the contact property between the Ti film 5 and the diffusion layer 2. However, even by this nitrogen treatment, the oxygen that has oxidized the surface of the TiN film 6 is removed by this Ti
It is difficult to separate it from the N film 6a. This nitrogen treatment stops the progress of oxidation on the surface of the TiN film 6a.

The nitrogen treatment includes, for example, lamp annealing in a nitrogen atmosphere. In this case, the lamp anneal is suitably performed in the temperature range of 400 ° C to 1000 ° C. If the nitrogen treatment is performed at a temperature lower than 400 ° C., the “nitridation” of the TiN film formed by sputtering or the like is incomplete, and it becomes difficult to secure the barrier property between the wiring made of the Al alloy film and the diffusion layer 2. The junction leak between the diffusion layer 2 and the silicon substrate 1 increases. Further, in the case of lamp annealing at a temperature higher than 1000 ° C., impurities (for example, constituent components of the interlayer insulating film such as Si, Ti or oxygen) are rediffused and redistributed, and the contact resistance becomes unstable, The electrical characteristics of the semiconductor device will vary. Another method for nitrogen treatment is 400 ° C to 600 ° C.
Furnace annealing in a nitrogen atmosphere at 400 ℃ to 80 ℃
Nitrogen plasma treatment at 0 ° C. is available. The lower limit of the temperature range in these other nitrogen treatments is determined from the conditions for ensuring complete barrier properties. Further, the upper limit of the temperature range of these other nitrogen treatments is determined from the viewpoint of avoiding re-diffusion and re-distribution of impurities, as in the above lamp annealing.

Next, in the same vacuum chamber, the film thickness is 0.05 μm.
Second TiN film 7 and, for example, Al-1% Si-
An Al alloy film 8a made of 0.5% Cu and having a film thickness of about 0.5 μm is sequentially deposited on the entire surface by sputtering [FIG. 1 (c)].

The thickness of the second TiN film 7 needs to be 0.02 m or more to completely cover the surface of the TiN film 6a having the oxidized surface, does not deteriorate the contact shape, and is made of Al alloy. The thickness is required to be 0.1 μm or less in order not to affect the embedding property when the film 8a is reflowed.

Next, for example, in the same vacuum chamber in which the TiN film 7 and the Al alloy film 8a are formed, heating is performed at a temperature of about 450 ° C. for about 180 seconds. The main reason for performing this process in the same vacuum chamber is economics. By this process, the Al alloy film 8a is reflowed and the Al alloy film 8aa is reflowed.
Therefore, the contact hole 4 is filled with the Al alloy film 8aa without generation of voids and spikes. After being taken out from the vacuum chamber, the Al alloy film 8a, the TiN film 7, and the T film are formed by a known lithography technique and dry etching technique
The iN film 6a and the Ti film 5 are sequentially patterned, and T
i film 5, TiN film 6a, TiN film 7 and Al alloy film 8
The wiring 18 is formed by laminating aa [FIG. 1
(D)].

The reason for interposing the second TiN film 7 between the Al film 8a and the TiN film 6a will be described. The TiN film 7 is provided to ensure wettability with the Al film 8a in the reflow. If the TiN film 7 is not present, the Al film 8a comes into direct contact with the TiN film 6a having the oxidized surface, and it becomes difficult to secure the wettability in the reflow process. Further, the TiN film 7 and the Al alloy film 8a are formed in the same vacuum chamber.
This is to prevent deterioration of the wettability with the Al film 8a due to the oxidation of the surface of the TiN film 7. Instead of the TiN film 7,
It is not preferable to use a Ti film having excellent wettability with the Al alloy film. This is because if the Ti film is oxidized by the oxygen on the surface of the TiN film 6a, the wettability is extremely lowered, it becomes difficult to secure the barrier property, and spikes are easily generated.

[0022]

As described above, according to the method of manufacturing a semiconductor device of the present invention, at least S provided on the interlayer insulating film is formed.
In a method of manufacturing a semiconductor device for electrically connecting a wiring made of an Al alloy film containing i to a diffusion layer through a contact hole, a spike is generated in the diffusion layer without generating a void in the contact hole. The contact hole can be buried by reflowing the Al alloy film without generating the above. Therefore, it is easy to suppress the increase in contact resistance and avoid the occurrence of junction leak.

[Brief description of drawings]

FIG. 1 is a sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main manufacturing process of a conventional semiconductor.

FIG. 3 is a cross-sectional view of another conventional main manufacturing process of a semiconductor.

FIG. 4 is a cross-sectional view of the main manufacturing process for explaining the problems of the conventional method for manufacturing a semiconductor device.

FIG. 5 is a cross-sectional view of a main manufacturing process for explaining a problem of another conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 Silicon substrate 2 Diffusion layer 3 Interlayer insulation film 4 Contact hole 5 Ti film 6, 6a, 7 TiN film 8a, 8aa, 8b, 8ba, 8c Al alloy film 9 Barrier metal film 10 Void 11, 11a Spike 18 Wiring

Claims (6)

[Claims] 1. A step of depositing an interlayer insulating film on a silicon substrate having a diffusion layer formed on a surface thereof, and forming a contact hole reaching the diffusion layer in the interlayer insulating film; A step of sequentially depositing a titanium film and a first titanium nitride film on the surface of the interlayer insulating film, a step of performing a nitrogen treatment, and a step of depositing a second titanium nitride film on the surface of the first titanium nitride film in a vacuum chamber. And a step of depositing an aluminum alloy film containing at least silicon on the surface of the second titanium nitride film in the vacuum chamber, fluidizing the aluminum alloy film by high temperature heating,
Filling the contact hole with the aluminum alloy film; patterning the aluminum alloy film, the second titanium nitride film, the first titanium nitride film, and the titanium film in sequence to form wiring. A method of manufacturing a semiconductor device, comprising: 2. The deposition of the second titanium nitride film, the deposition of the aluminum alloy film, and the fluidization of the aluminum alloy film are performed continuously in the vacuum chamber. Of manufacturing a semiconductor device of. 3. The film thickness of the second titanium nitride film is 0.
The method for manufacturing a semiconductor device according to claim 1, wherein the thickness is from 0.2 μm to 0.1 μm. 4. The nitrogen treatment is 400 ° C. to 1000 ° C.
4. The method of manufacturing a semiconductor device according to claim 1, wherein the lamp annealing is performed in a nitrogen atmosphere. 5. The method of manufacturing a semiconductor device according to claim 1, wherein the nitrogen treatment is furnace annealing in a nitrogen atmosphere at 400 ° C. to 600 ° C. 6. The nitrogen treatment according to claim 1, wherein the nitrogen treatment is a nitrogen plasma treatment at 400 ° C. to 800 ° C.
A method of manufacturing a semiconductor device according to claim 2 or 3.