JP2001028349A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability of a cobalt silicide process. SOLUTION: Related to a manufacturing process for a semiconductor device of a cobalt silicide process structure on a cobalt film 37 formed over a silicide formation region, an oxidation suppressing film (cobalt nitride film 38) comprising the same component as the cobalt film 37 is laminated, and then via the cobalt nitride film 38, a process is included in which the cobalt film 37 is thermally processed for siliciding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a technique for forming a silicide film in a silicide process of a semiconductor device.

[0002]

2. Description of the Related Art FIGS. 3 and 4 are views for explaining formation of a conventional silicide film, particularly a titanium silicide film in a titanium silicide process.

Here, by selectively and self-aligningly forming a silicide structure on the polysilicon gate of the MOS transistor and the surface layer of the source / drain region, the wiring resistance of the polysilicon gate and the parasitic resistance of the source / drain region are formed. , And wiring delay and conductance degradation can be suppressed.

[0004] In the silicide forming method, first, FIG.
As shown in FIG. 1, an element isolation film 2 is formed on a semiconductor wafer 1 of one conductivity type, for example, a P-type, a polysilicon gate 3 is formed on an active region via a gate oxide film, and is adjacent to the polysilicon gate 3. After the source / drain regions 4 of the opposite conductivity type, for example, N-type, are formed on the surface of the wafer, the sidewall insulating film 5 is formed on the sidewall of the polysilicon gate 3.

Next, as shown in FIG. 3B, a metal film, for example, a titanium (Ti) film 6 is deposited on the entire surface and heat-treated (rapid thermal annealing, hereinafter referred to as RTA).
The surface layers of the polysilicon gate 3 and the source / drain regions 4 are selectively and self-aligned into silicide. Note that R
TA treatment is performed to prevent excessive silicide film formation.
Going in steps. That is, the first RTA process is performed in a nitrogen (N ₂ ) atmosphere at about 650 ° C. to 700 ° C.
The process is performed for about 0 second to form a metastable C49 phase titanium silicide (TiSi ₂ ) film 7A.

Subsequently, as shown in FIG. 4A, after the titanium nitride film or the titanium film on the insulating film is selectively etched and removed using a mixed solution of ammonia water and hydrogen peroxide solution, a second etching is performed. RTA treatment of about 750 ° C. to 85
Perform for about 30 seconds in a nitrogen atmosphere at 0 ° C.
A 54-phase stable titanium silicide (TiSi ₂ ) film 7 is formed.

Then, as shown in FIG. 4B, after an interlayer insulating film 8 is formed on the entire surface, a contact hole 9 for contacting the source / drain region 4 is formed, and a barrier is formed on the source / drain region 4. A metal (for example, Al alloy) wiring 11 is formed via a metal film 10.

[0008]

However, the silicide process described above is not a completed technology, and various developments are currently underway.

Then, as the material of the film to be silicided,
Mainly, a titanium film has been generally used.

However, in order to further reduce the resistance, cobalt (C) is used as a new material in place of the titanium film.
o) Films are receiving attention.

Since the cobalt film has a smaller crystal diameter than the titanium film and does not cause an increase in resistance in a fine wire portion, it can be applied particularly to a thin wiring structure or a film having a short gate length. Establishing a silicide process using a cobalt film is an important technique for realizing a miniaturization process of, for example, 0.35 μm or less.

However, the cobalt film has a surface that is more difficult to handle than the titanium film. That is, the cobalt film is a material that is very easily oxidized, and it is necessary to suppress the oxidation in the heat treatment (annealing) step when forming the cobalt silicide (CoSi ₂ ) film. Therefore, an annealing process has been performed in a state where an oxidation suppressing film made of a titanium nitride (TiN) film, which is a well-known barrier film, is formed on the upper surface of the cobalt film.

The problem here is that two sputtering apparatuses or two chambers are required to form a cobalt film and a titanium nitride film (titanium film) by sputtering, and the throughput is low. That is to say. In addition, the annealing step is usually performed in two steps so as not to cause an excessive silicidation reaction. However, when performing wet etching after the first annealing step, the wet etching for removing the titanium nitride film is performed. Etching with aqueous ammonia (NH ₃ OH) and aqueous hydrogen peroxide (H ₂ O ₂ ) and hydrochloric acid (HCl) and aqueous hydrogen peroxide (H ₂ O ₂ ) or sulfuric acid (H ₂ SO ₂ ) for removing the cobalt film ₄ ) and etching with a hydrogen peroxide solution (H ₂ O ₂ ) must be performed in two steps, and the manufacturing process is complicated.

Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor device which is easy to be oxidized as described above and which can improve workability and rationalize a manufacturing process in a silicide process using a cobalt film.

[0015]

Accordingly, the present invention relates to a method of manufacturing a semiconductor device having a cobalt silicide structure, wherein a cobalt film 37 formed on a silicide formation region is formed on a cobalt film 37 as shown in FIG. After laminating an oxidation inhibiting film (cobalt nitride film 38) containing components,
Heat-treating the cobalt film 37 via the cobalt nitride film 38 to form a cobalt silicide film 39.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for manufacturing a semiconductor device according to the present invention will be described below with reference to the drawings.

In FIG. 1A, one conductivity type, for example, P
A device isolation film 32 is formed on a semiconductor wafer 31 of a mold type, and a polysilicon gate 33 is formed on an active region via a gate oxide film.
Is formed on the surface layer of the wafer so as to be adjacent to the polysilicon gate 33, and then a source / drain region 34 of an N type is formed. . Note that a P-type source / drain region may be formed in an N-type region.

Next, after mounting the wafer 31 in a sputtering apparatus (not shown), as shown in FIG. 1B, a metal film, for example, cobalt (Co) having a film thickness of about 50 to 300.degree. The film 37 is deposited by sputtering.

Subsequently, in the sputtering apparatus, as shown in FIG. 1C, the cobalt film 37 is nitrided on the cobalt film 37 to a thickness of about 50.degree.
N) A film 38 is formed. The cobalt nitride film 38 is oxidized more than necessary in a heat treatment (annealing) step of reacting the cobalt film with the underlying silicon film to form cobalt silicide. It serves as an oxidation inhibiting film for preventing the formation of the film. Here, the cobalt nitride film 38 is
Since a nitrogen (N ₂ ) gas may be supplied into the sputtering apparatus used for the formation of 7, continuous work is possible and workability is good.

This step is a step which is a feature of the present invention. In this step, a cobalt nitride film 38 containing the same material as the cobalt film 37 is formed as an oxidation suppressing film. Since the film 38 can be formed in the same sputtering apparatus, workability is good. Therefore, it is possible to solve the problem related to the sputter deposition of the conventional cobalt silicide process, that is, the problem that two sputter devices or two chambers are required and that the throughput is deteriorated. Furthermore, in the combination of the conventional cobalt film and titanium nitride film,
As described above, after the first RTA process described below, the titanium nitride film and the cobalt film must be removed in two steps using two chemical solutions. In combination, hydrochloric acid (HCl) and aqueous hydrogen peroxide (H ₂ O ₂ ) or sulfuric acid (H
_The treatment can be performed with one chemical solution composed of ₂ SO ₄ ) and hydrogen peroxide solution (H ₂ O ₂ ), and the production process can be streamlined.

[0021] In addition, as can be seen from already generalized films such as a titanium nitride film and a tantalum nitride (TaN) film, a nitrided metal has an excellent barrier property, so that oxidation is suppressed. It can be sufficiently used as a film. Therefore, a stable low-resistance cobalt silicide film can be formed.

Then, the cobalt film 37 is heat-treated (rapid thermal annealing, hereinafter referred to as RTA) through the cobalt nitride film 38 to selectively form the surface layers of the polysilicon gate 33 and the source / drain regions 34. Then, a cobalt silicide (CoSi ₂ ) film is formed. Note that R
TA processing is performed in two steps so that excessive silicidation does not progress.

First, as shown in FIG. 2A, the first RTA process is performed at about 500 ° C. to 600 ° C. with nitrogen (N ₂ ).
This is performed for about 30 seconds in an atmosphere to form a metastable cobalt silicide film (see the hatched area in the figure).

Then, the cobalt nitride film and the unreacted cobalt film on the insulating films such as the element isolation film 2 and the side wall insulating film 5 are converted into hydrochloric acid (HCl) and hydrogen peroxide solution (H ₂ O ₂ ) or sulfuric acid (H After selective etching and removal using a mixed solution of ₂ SO ₄ ) and hydrogen peroxide solution (H ₂ O ₂ ), a second RTA treatment was performed at about 750 ° C. to 850 ° C. as shown in FIG. This is performed for about 30 seconds in a nitrogen atmosphere to form a stable cobalt silicide (CoSi ₂ ) film 39 having lower resistance. At this time, since the cobalt film and the cobalt nitride film are combined as described above, the cobalt nitride film and the unreacted cobalt film can be removed by etching with one chemical solution.
The manufacturing process can be simplified.

After forming an interlayer insulating film 40 on the entire surface as shown in FIG. 2C, a contact hole 41 is formed on the source / drain region 34 to make contact with the source / drain region 34. Metal film 42
A metal (for example, Al alloy) wiring 43 is formed through the substrate.

As described above, in the present invention, by forming the cobalt nitride film 38 containing the same material as the cobalt film 37 as the oxidation suppressing film, the sputter deposition in the cobalt silicide process can be performed in one sputtering apparatus or in one sputtering apparatus. In one chamber. Therefore, the throughput can be increased.

[0027]

According to the present invention, in a silicide process using a cobalt film, an oxidation suppression film containing the same material as the cobalt film is used as an oxidation suppression film for the cobalt film, so that a single sputtering apparatus can be used. Alternatively, it becomes possible to perform sputter deposition in a cobalt silicide process in one chamber, and cost reduction can be achieved.

Further, since the sputtering deposition can be performed by one sputtering apparatus, the throughput can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 4 is a cross-sectional view illustrating a conventional method for manufacturing a semiconductor device.

Claims (3)

[Claims] 1. A method of manufacturing a semiconductor device having a cobalt silicide structure, comprising: laminating an oxidation inhibiting film containing the same component as a cobalt film on a cobalt film formed on a silicide formation region; A heat treatment of the cobalt film to form a silicide. 2. A method for manufacturing a semiconductor device having a cobalt silicide structure, comprising: forming a cobalt film by sputtering on a silicide formation region in a sputtering device; and continuously forming the cobalt film in the same chamber or in the same sputtering device. A step of laminating an oxidation inhibiting film containing the same component as that of the cobalt film, and a step of heat-treating the cobalt film through the oxidation inhibiting film to form a silicide. 3. The method according to claim 1, wherein the oxidation inhibiting film is a nitrided cobalt nitride film.