JP2768304B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device having a contact hole (or through hole) filled with tungsten, that is, a tungsten plug.

[0002]

2. Description of the Related Art As semiconductor devices have become more highly integrated in recent years, contact holes have become finer and the aspect ratio has become increasingly higher. As a result, reduction in step coverage of a wiring layer inside the contact holes has become a problem. ing.
One of the fine contact connection techniques for solving this problem is a tungsten plug contact method. FIG. 5 is a sectional view of a tungsten plug formed by a conventional technique.

In FIG. 1, A shows a state of a product forming area, and B shows a state of a wafer peripheral area. After the field oxide film 2 and the diffusion layer region 3 are formed on the silicon substrate 1, for example, a silicon dioxide film is formed as the first interlayer insulating film 4 by using the CVD method. After that, a BPSG film is deposited by using the CVD method, and then a heat treatment is performed to cause reflow to form a second interlayer insulating film 5. Subsequently, a contact hole for exposing the surface of the diffusion layer region 3 is opened by using a photolithography technique and a dry etching method. Next, a titanium film 9 and a titanium nitride film 10 are sequentially deposited by using a sputtering method.

At this time, in the wafer peripheral area B, the accuracy of the wafer alignment by the sputtering apparatus is insufficient.
A titanium film exposed region C that is not covered with the titanium nitride film is formed. Thereafter, a tungsten plug is formed by forming a tungsten film 10 on the entire surface by using the CVD method and then performing etch back to leave the tungsten film only in the contact hole. Next, the A
After the l film 11 is deposited, it is processed into a desired pattern by using a photolithography technique and a dry etching method, whereby the semiconductor device shown in FIG. 5 is obtained.

[0005]

In the tungsten plug formed by the above-described conventional technique, the wafer peripheral region B
In this case, an exposed portion of the titanium film is formed. Since this titanium film does not have high adhesion to the underlying BPSG film and has high reactivity, when a tungsten film is formed by the CVD method, WF ₆ as a source gas reacts with the titanium film to form a second interlayer. It easily peels off from the insulating film.
As a result, there has been a problem that particles are generated and the yield is reduced.

Accordingly, it is an object of the present invention to suppress the reaction of the titanium film and enhance the adhesion of the titanium film to improve the C
The purpose of this is to prevent the titanium film from being peeled off when the tungsten film is formed by the VD method, and thereby to improve the production yield.

[0007]

According to the present invention, there is provided, according to the present invention, a step of forming an insulating film on a semiconductor substrate or a lower wiring formed on the semiconductor substrate; Selectively removing and forming an opening exposing the surface of the diffusion layer or the lower wiring formed on the surface of the semiconductor substrate; and forming a polycrystalline silicon film, a titanium film and a titanium nitride film on the entire surface including the inside of the opening. A step of depositing in this order; and 700 to 8 by a lamp anneal in a nitrogen atmosphere.
The surface of the exposed titanium film is nitrided by performing a heat treatment at 00 ° C. for a predetermined time, and the polycrystalline silicon film and the
Manufacturing a semiconductor device which comprises forming a titanium silicide layer on the field surface with the titanium film, a step of filling the performing deposited tungsten etch back in the opening of tungsten by a CVD method, a A method is provided.

Further, according to the present invention, a step of forming an insulating film and a polycrystalline silicon film on a semiconductor substrate or a lower wiring formed on the semiconductor substrate; and selecting the polycrystalline silicon film and the insulating film. Forming a diffusion layer formed on the surface of the semiconductor substrate or an opening exposing the surface of the lower wiring; and depositing a titanium film and a titanium nitride film in this order on the entire surface including the inside of the opening. 700-8 by lamp annealer in nitrogen atmosphere
The surface of the exposed titanium film is nitrided by performing a heat treatment at 00 ° C. for a predetermined time, and the polycrystalline silicon film and the
Manufacturing a semiconductor device which comprises forming a titanium silicide layer on the field surface with the titanium film, a step of filling the performing deposited tungsten etch back in the opening of tungsten by a CVD method, a A method is provided.

[0009]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a semiconductor device formed according to a first embodiment of the present invention, and FIGS. 2 (a) to 2 (c).
FIG. 3 is a process cross-sectional view showing the manufacturing method according to the first example of the present invention in the order of processes. Since the structure of the semiconductor device of the present embodiment shown in FIG. 1 will be clarified by describing the manufacturing method thereof, the manufacturing method will be described below with reference to FIG. First, a field oxide film 2 is formed on the surface of a silicon substrate 1 by a LOCOS method, and a diffusion layer region 3 is formed in an active region defined by the field oxide film.

Next, for example, a silicon dioxide film is deposited on the surface of the silicon substrate by a CVD method to form a first interlayer insulating film 4, and further, a CVD is formed on the first interlayer insulating film 4.
A second interlayer insulating film 5 made of a BPSG film is formed by a method. After the surface of the second interlayer insulating film 5 is flattened by a reflow process, a contact hole 6 is opened by using a photolithography technique and an anisotropic dry etching method. Subsequently, a polycrystalline silicon film 7 is deposited in the contact hole 6 and on the second interlayer insulating film 5 to a thickness of about 500 ° by using the CVD method. Then, the diffusion layer region 3
Is an n-type diffusion layer, for example, phosphorus is implanted into the entire surface to lower the resistance of the polycrystalline silicon film 7 (FIG. 2A).

After that, the titanium film 8 is
A titanium nitride film 9 is sequentially deposited to a thickness of about 1000 ° to a thickness of about 00 °. At this time, a titanium film exposed region C in which the titanium film is not covered with the titanium nitride film is formed in the wafer peripheral region B due to the lack of accuracy of the wafer alignment of the sputtering apparatus [FIG. 2B]. Then, in a nitrogen gas atmosphere, 700 ° C.
A nitriding treatment for performing rapid heating at about 800 ° C. for about 1 minute is performed. Thereby, an adhesion layer of a titanium silicide layer is formed between the titanium film 8 and the polycrystalline silicon film 7 under the titanium film 8 by the reaction between the titanium film 8 and the surface of the titanium film exposed region C which is not covered with the titanium nitride film. Has about 200-30
A 0 ° titanium nitride layer is formed.

Thereafter, a tungsten film 10 is grown on the entire surface of the wafer by using the CVD method, and etched back to form a tungsten plug leaving the tungsten film 10 only inside the contact hole [FIG. 2 (c)]. In the above-described step of forming the tungsten film, the reaction between the WF ₆ gas and the titanium film is suppressed because the surface of the titanium film is nitrided, and the titanium film may react with the WF ₆ in some cases. Also, the titanium film 8 and the polycrystalline silicon film 7
Since an adhesion layer made of a titanium silicide layer is formed between the BPSG film 5 and the BPSG film 5, peeling of the titanium film 8 is prevented. Thereafter, an Al film 11 is formed on the entire surface, and is patterned using a photolithography technique and a dry etching method to form an Al wiring, whereby the semiconductor device shown in FIG. 1 is obtained.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a sectional view of a semiconductor device formed according to the second embodiment of the present invention.
4A to 4C are process cross-sectional views illustrating a manufacturing method according to a second embodiment of the present invention in the order of processes. Hereinafter, the manufacturing method will be described with reference to FIG. After a field oxide film 2 and a diffusion layer region 3 are formed on the surface of a silicon substrate by using a method similar to the method described in the first embodiment, silicon dioxide and BPSG are deposited to form first and second layers. The interlayer insulating films 4 and 5 are formed. Thereafter, a polycrystalline silicon film 7 is formed on the second interlayer insulating film 5 by the CVD method.
Deposit to a thickness of about Å.

Subsequently, the contact holes 6 are formed by selectively etching and removing the polycrystalline silicon film 7 and the second and first interlayer insulating films sequentially using a photolithography technique and a dry etching technique [FIG. (A)].

After that, a film thickness of about 600
A titanium film 8 of {circle around (1)} and a titanium nitride film 9 of a thickness of about 1000 mm are sequentially deposited (FIG. 4B). Then, as in the case of the first embodiment, a rapid thermal nitridation process in the range of 700 ° C. to 800 ° C. is performed to nitride the titanium film surface in the titanium film exposed region C, and to form a tungsten film when forming a tungsten film later. The reaction with the WF ₆ gas can be suppressed, and the titanium film 8 and the polycrystalline silicon film 7 react to form an adhesion layer made of titanium silicide between the two films.

Thereafter, a tungsten film 10 is grown on the entire surface of the wafer by using the CVD method, and etched back to leave the tungsten film 10 only inside the contact hole (FIG. 4C). After that, an Al film 11 is formed on the entire surface,
If the upper layer Al wiring is formed by patterning using a photolithography technique and a dry etching method, the semiconductor device of the second embodiment shown in FIG. 3 can be obtained.

While the preferred embodiment has been described above,
The present invention is not limited to these embodiments, but can be appropriately modified within the scope described in the claims. For example, in the embodiment, the interlayer insulating film is formed by the silicon dioxide film or the BPSG film, but at least one of them can be replaced by the PSG film. Further, in the embodiment, the example in which the contact hole is formed on the diffusion layer has been described. However, the present invention can be applied to a through hole between wiring layers.

[0018]

As described above, according to the present invention, in a semiconductor device having a tungsten plug formed through a barrier layer composed of a titanium film and a titanium nitride film, a polycrystalline silicon film is provided below the titanium film. Performing a thermal nitridation process after forming the barrier layer to form a titanium nitride film on the exposed surface of the titanium film and to form a titanium silicide film between the titanium film and the polycrystalline silicon film. Therefore, according to the present invention, it is possible to suppress the reaction between the WF ₆ gas and the titanium film when the tungsten film is formed by the CVD method. Even if the titanium film reacts with the WF ₆ through the thin titanium nitride film, since the adhesion layer is formed between the titanium film and the polycrystalline silicon film, the titanium film may not react with the lower insulating film. Peeling can be prevented. Thus, according to the present invention,
It is possible to prevent the generation of particles that have conventionally occurred, and to improve the yield.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor device manufactured according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view in a process order for describing a method of manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 3 is a sectional view of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view in a process order for describing a method of manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a semiconductor device formed by a conventional method.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 field oxide film 3 diffusion layer region 4 first interlayer insulating film 5 second interlayer insulating film 6 contact hole 7 polycrystalline silicon film 8 titanium film 9 titanium nitride film 10 tungsten film 11 Al film A product formation region B Wafer peripheral area C Titanium film exposed area

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H01L 21/3205 H01L 21/3213 H01L 21/768 H01L 21/28-21/288 H01L 29/40-29 / 51

Claims (2)

(57) [Claims] (1) forming an insulating film on a semiconductor substrate or on a lower wiring formed on the semiconductor substrate; and (2) forming an insulating film on the surface of the semiconductor substrate by selectively removing the insulating film. Forming an opening exposing the surface of the diffusion layer or the lower wiring, and (3) depositing a polycrystalline silicon film, a titanium film, and a titanium nitride film in this order on the entire surface including the inside of the opening, (4) ) 700 ~ by lamp annealer in nitrogen atmosphere
With nitriding the surface of the titanium film exposed by performing a predetermined time heat treatment at 800 ° C. the polycrystalline silicon film and before
Forming a titanium silicide layer on the field surface with the serial titanium film, characterized in that it comprises a a step of said inside opening etched back by depositing tungsten to fill tungsten by (5) CVD method A method for manufacturing a semiconductor device. 2. A step of (1) forming an insulating film and a polycrystalline silicon film on a semiconductor substrate or on a lower wiring formed on the semiconductor substrate; and (2) selecting the polycrystalline silicon film and the insulating film. Forming a diffusion layer formed on the surface of the semiconductor substrate or an opening exposing the surface of the lower wiring; and (3) depositing a titanium film and a titanium nitride film in this order on the entire surface including the inside of the opening. (4) In a nitrogen atmosphere, 700-
With nitriding the surface of the titanium film exposed by performing a predetermined time heat treatment at 800 ° C. the polycrystalline silicon film and before
Forming a titanium silicide layer on the field surface with the serial titanium film, characterized in that it comprises a a step of said inside opening etched back by depositing tungsten to fill tungsten by (5) CVD method A method for manufacturing a semiconductor device.