JP3353732B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory device and a method of manufacturing the same, and more particularly to a technique using a pad structure in a semiconductor memory device.

[0002]

2. Description of the Related Art In recent years, a pad structure technique has been used to prevent a contact hole from becoming deep and a positioning margin from becoming strict due to miniaturization of a semiconductor. A technique using this pad structure will be described with reference to FIG.

FIG. 4 is a longitudinal sectional view for explaining a conventional manufacturing method. STI (Shall) is formed on a semiconductor substrate 1.
Then, an element isolation 2 is formed by ow trench isolation, and then a gate oxide film 3 and a conductive film 4 made of a polycrystalline silicon film or a tungsten polycide film are formed (see FIG. 4A).

Next, the gate oxide film 3 and the conductive film 4 are patterned into a predetermined shape using a photoresist, and dry etching is performed to form a gate electrode 5. Thereafter, an interlayer insulating film 15 is formed, and CMP (Cha) is formed.
mechanical Mechanical Polish
g) or the like is used to perform flattening. Subsequently, after patterning is performed using a photoresist, dry etching is performed to form a contact hole 7 (see FIG. 4B).

[0005] Polycrystalline silicon is buried in the contact hole 7 and patterned using a photoresist. Further, the pad 16 is formed by etching the polycrystalline silicon by dry etching [see FIG. 4 (c)].

After an interlayer insulating film 17 is formed on the pad 16, a contact hole 12 is formed on the pad 16 by using a photoresist and dry etching [FIG.
(D)].

In the above-described pad structure technology, the distance between the pads 16 becomes short and the patterning of the photoresist becomes severe, so that the pad cannot be formed large. Therefore, the contact is formed on the pad due to the misalignment of the contact. May not be done.

In order to solve this problem, a method as shown in FIG. 5 has been proposed. That is, an element isolation 2 is formed on the semiconductor substrate 1 by STI, and thereafter, a gate oxide film 3 and a conductive film 4 made of a polycrystalline silicon film or a tungsten polycide film are formed (see FIG. 5A).

Next, the gate oxide film 3 and the conductive film 4 are patterned into a predetermined shape using a photoresist, and dry etching is performed to form a gate electrode 5. After that, BPSG (Boro-Phosph-Si)
(Liquid Glass) film 6, and the BPSG film 6 is polished and flattened using CMP.

Then, after patterning the BPSG film 6 using a photoresist, dry etching is performed to form a contact hole 7 (see FIG. 5B). Thereafter, polycrystalline silicon is buried in the contact hole 7 and etched back using dry etching to form a contact plug 8 of polycrystalline silicon.

Further, the BPSG film 6 is etched back by wet etching or dry etching using hydrofluoric acid or the like, exposing the upper portions of the contact plugs 8 (see FIG. 5C), and forming polycrystalline silicon 18 [FIG. FIG. 5 (d)].

Thereafter, the polysilicon 18 is etched back by dry etching to form a polysilicon sidewall 19 of the polysilicon 18 on the side wall of the contact plug 8. As a result, a pad formed by the contact plug 8 and the polysilicon sidewall 19 is formed.

Thereafter, an interlayer insulating film 11 is formed, and the contact plug 8 and the polysilicon sidewall 19 are formed.
A contact hole 12 is formed on the top using a photoresist and dry etching [see FIG. 5E].

[0014]

In the above-mentioned conventional pad structure technology, a polycrystalline silicon sidewall is formed on a side wall of a contact plug to increase an alignment margin with respect to a pad when forming a contact. As the size of the semiconductor device is reduced, the distance between the adjacent contact plug and the sidewall may be further reduced. In that case, there is a possibility that a short circuit occurs when the distance between the adjacent sidewalls is reduced.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to form a large pad with a slit narrower than the resolution limit of a photoresist without causing a short circuit even when the distance between adjacent sidewalls is further reduced. And a method of manufacturing the same.

[0016]

According to the present invention, there is provided a semiconductor device in which an insulating film is formed on a gate electrode formed on a semiconductor substrate and a first region formed in a predetermined region of the insulating film. > A contact film is formed by forming a conductive film in the contact hole, and an interlayer insulating film is formed on the contact plug.
A second contact hole formed in a predetermined region of the interlayer insulating film, wherein the second contact hole is formed on an exposed side wall of the contact plug and made of a silicon nitride film. Provided by the sidewall
Etching for forming the second contact hole
Has stopped .

In another semiconductor device according to the present invention, an insulating film is formed on a gate electrode formed on a semiconductor substrate, and a conductive film is formed in a first contact hole formed in a predetermined region of the insulating film. A contact plug is formed, an interlayer insulating film is formed on the contact plug,
A semiconductor device in which a second contact hole is formed in a predetermined region of an insulating film , wherein a first silicon nitride film for stopping a process of exposing a side wall of the contact plug at a predetermined position; A sidewall formed on a side wall of the contact plug and made of at least a second silicon nitride film ;
Etching for forming the second contact hole is performed.
Top .

Method for producing a [0018] semiconductor device according to the present invention, the insulating film is formed on the gate electrode formed on a semiconductor substrate, a first contour <br/> transfected formed in a predetermined region of the insulating film Forming a conductive film in the hole to form a contact plug; forming an interlayer insulating film on the contact plug;
A method of manufacturing a semiconductor device, wherein a second contact hole is formed in a predetermined region of the interlayer insulating film , wherein a step of exposing a side wall of the contact plug includes a step of exposing a side wall made of a silicon nitride film on the side wall of the contact plug. and forming a wall, before the said side walls
The etching for forming the second contact hole is stopped.
Ppushi to have.

The method of manufacturing another semiconductor device according to the present invention, the insulating film is formed on the gate electrode formed on a semiconductor substrate, a first <br/> formed in a predetermined region of the insulating film A contact plug is formed by forming a conductive film in the contact hole, and an interlayer insulating film is formed on the contact plug.
A method of manufacturing a semiconductor device in which a second contact hole is formed in a predetermined region of the interlayer insulating film , wherein a process of exposing a side wall of the contact plug is stopped at a predetermined position. comprising a step of forming a first silicon nitride film, exposing a side wall of the contact plug, and forming at least a side wall consisting of the second silicon nitride film on the side wall of the contact plug, before
The second contact hole is formed by the sidewall.
Etching at the time of formation is stopped .

That is, the semiconductor device of the present invention is a semiconductor device in which a gate electrode is formed on a semiconductor substrate, an insulating film is formed on the gate electrode, and a contact hole is formed in a predetermined region of the insulating film. ing. A first conductive film is formed in the contact hole, and the first conductive film is etched back to form a plug made of the first conductive film in the contact hole.

By forming a sidewall made of a nitride film on the side wall of the contact plug, etching can be stopped by the sidewall made of the nitride film even if an alignment shift occurs during contact formation. Therefore, even if the distance from the adjacent sidewall is further reduced, it is possible to form a large pad with a slit narrower than the resolution limit of the photoresist without causing a short circuit.

[0022]

Next, an embodiment of the present invention will be described with reference to the drawings. 1A to 1E are cross-sectional views illustrating a process for manufacturing a semiconductor device according to an embodiment of the present invention. With reference to FIGS. 1A to 1E, description will be made on a manufacturing process of a semiconductor device according to an embodiment of the present invention.

First, a device isolation 2 is formed on a semiconductor substrate 1 by STI, and then a gate oxide film 3 of about 100 ° is formed.
And a polycrystalline silicon film or a tungsten polycide film of about 2000.degree.
(A)].

Next, a gate electrode 5 is formed by patterning into a predetermined shape using a photoresist and performing dry etching. After that, 8000Å BPSG (Bo
ro-Phosph-Silicate Glass)
An interlayer insulating film is formed by the film 6, and a CMP (Chemic)
The BPSG film 6 is polished by 2000 ° using Al Mechanical Polishing, and is planarized.

Subsequently, after patterning is performed using a photoresist, dry etching is performed to form a contact hole 7 (see FIG. 1B). Thereafter, 5000 ° polycrystalline silicon is buried in the contact hole 7 and etched back using dry etching to form a contact plug 8 made of polycrystalline silicon.

Further, the BPSG film 6 is formed by wet etching or dry etching using hydrofluoric acid or the like.
Etching back by 000 ° exposes the upper portion of the contact plug 8 (see FIG. 1C), and forms a silicon nitride film 9 (see FIG. 1D).

Thereafter, the silicon nitride film 9 is etched back by dry etching to form a silicon nitride film sidewall 10 of the silicon nitride film 9 on the side wall of the contact plug 8. As a result, a pad formed by the contact plug 8 and the silicon nitride film sidewall 10 is formed.

Thereafter, an interlayer insulating film 11 is formed, and the upper surface of the contact plug 8 and the silicon nitride film sidewall 10 are formed.
A contact hole 12 is formed on the top using a photoresist and dry etching [see FIG. 1 (e)].

FIGS. 2 (a) to 2 (d) and 3 (a),
FIG. 7B is a cross-sectional view showing a step of manufacturing a semiconductor device according to another embodiment of the present invention. With reference to FIGS. 2A to 2D and FIGS. 3A and 3B, a description will be given of a manufacturing process of a semiconductor device according to another embodiment of the present invention.

First, an element isolation 2 is formed on a semiconductor substrate 1 by STI, and then a gate oxide film 3 of about 100 ° is formed.
And a polycrystalline silicon film or a tungsten polycide film of about 2000.degree.
(A)].

Next, a gate electrode 5 is formed by patterning into a predetermined shape using a photoresist and performing dry etching. Thereafter, an interlayer insulating film of 8000 ° BPSG film 6 is formed, and BPSG film 6 is formed by CMP.
Is polished by 2000 ° to make it flat.

Subsequently, a silicon nitride film 13 and an oxide film 14 are formed on the BPSG film 6 (see FIG. 2B), and these BPSG film 6, silicon nitride film 13 and oxide film 14 are formed using a photoresist. To form a contact hole 7 by performing dry etching [FIG.
(C)].

Thereafter, 5000 ° polycrystalline silicon is buried in the contact hole 7 and etched back using dry etching to form a contact plug 8 made of polycrystalline silicon.
To form However, this etch back stops at the silicon nitride film 13 and the upper part of the contact plug 8 is exposed [see FIG. 2 (d)].

Further, a silicon nitride film 9 is formed on the contact plug 8 and the silicon nitride film 13 (see FIG. 3A). Thereafter, the silicon nitride films 9 and 13 are etched back by dry etching to form silicon nitride film sidewalls 10 on the sidewalls of the contact plug 8. As a result, a pad formed by the contact plug 8 and the silicon nitride film sidewall 10 is formed.

Thereafter, an interlayer insulating film 11 is formed, and the upper surface of the contact plug 8 and the silicon nitride film sidewall 10 are formed.
A contact hole 12 is formed on the top using a photoresist and dry etching [see FIG. 3B].

As described above, by forming the sidewall (silicon nitride film sidewall 10) by the nitride film on the side wall of the contact plug 8, a large pad can be formed with a slit narrower than the resolution limit of the photoresist. it can. Thereby, the alignment margin can be increased at the time of contact formation.

That is, by forming a sidewall made of a nitride film on the side wall of the contact plug 8, even if an alignment shift occurs during the formation of the contact, the etching can be stopped by the sidewall made of the nitride film.

Further, by using the silicon nitride films 9 and 13 for the side walls, even if the distance between the adjacent contact plugs and the side wall is further reduced, no short circuit occurs.

[0039]

As described above, according to the present invention, an insulating film is formed on a gate electrode formed on a semiconductor substrate, and a conductive film is formed in a contact hole formed in a predetermined region of the insulating film. In a semiconductor device in which a contact plug is formed by forming a sidewall made of a silicon nitride film on a side wall of an exposed contact plug, short-circuiting does not occur even when the distance between the adjacent sidewall is further reduced. There is an effect that a large pad can be formed with a slit narrower than the resolution limit of the photoresist.

[Brief description of the drawings]

FIGS. 1A to 1E are cross-sectional views illustrating a manufacturing process of a semiconductor device according to an embodiment of the present invention.

FIGS. 2A to 2D are cross-sectional views illustrating a manufacturing process of a semiconductor device according to another embodiment of the present invention.

FIGS. 3A and 3B are cross-sectional views illustrating a manufacturing process of a semiconductor device according to another embodiment of the present invention.

4A to 4D are cross-sectional views illustrating an example of a manufacturing process of a semiconductor device according to a conventional example.

FIGS. 5A to 5E are cross-sectional views illustrating another example of a manufacturing process of a conventional semiconductor device.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 STI element isolation 3 gate oxide film 4 conductive film 5 gate electrode 6 BPSG film 7 contact hole 8 contact plug 9, 13 silicon nitride film 10 silicon nitride film sidewall 11 interlayer insulating film 12 contact hole 14 oxide film

Claims (10)

(57) [Claims] An insulating film is formed on a gate electrode formed on a semiconductor substrate, and a contact plug is formed by forming a conductive film in a first contact hole formed in a predetermined region of the insulating film. , Interlayer insulation on the contact plug
A semiconductor device in which a film is formed and a second contact hole is formed in a predetermined region of the interlayer insulating film, wherein the semiconductor device is formed on an exposed side wall of the contact plug and is formed of a silicon nitride film. the made side wall possess, the Saidowo
When forming the second contact hole by
A semiconductor device characterized by stopping the switching . 2. An insulating film is formed on a gate electrode formed on a semiconductor substrate, and a contact plug is formed by forming a conductive film in a first contact hole formed in a predetermined region of the insulating film. , Interlayer insulation on the contact plug
A semiconductor device in which a film is formed and a second contact hole is formed in a predetermined region of the interlayer insulating film , wherein a process of exposing a side wall of the contact plug is stopped at a predetermined position. a first silicon nitride film, is formed on the exposed sidewalls of the contact plug and possess the side wall of at least the second silicon nitride film, wherein
The second contact hole is formed by a sidewall.
A semiconductor device characterized by stopping etching when performing the etching . 3. The semiconductor device according to claim 2, wherein the sidewall is made of the first and second silicon nitride films.
13. The semiconductor device according to claim 1. 4. An insulating film is formed on a gate electrode formed on a semiconductor substrate, and a contact plug is formed by forming a conductive film in a first contact hole formed in a predetermined region of the insulating film. , Interlayer insulation on the contact plug
A method of manufacturing a semiconductor device in which a film is formed and a second contact hole is formed in a predetermined region of the interlayer insulating film , wherein a step of exposing a sidewall of the contact plug;
Have a forming side walls made of a silicon nitride film on the side wall of the contact plug, said Saidou
When the second contact hole is formed by
A method for manufacturing a semiconductor device, wherein etching is stopped . 5. A step of exposing the sidewalls of the contact plug, said a step of forming the conductive film on the first contact hole, the said conductive layer is etched back first <br/> contact hole 5. The method according to claim 4, further comprising: forming the contact plug therein; and etching back the insulating film to expose sidewalls of the contact plug. 6. The step of forming the sidewall,
Forming a silicon nitride film so as to cover the insulating film and the contact plug; and forming the sidewall on the side wall of the contact plug by etching back the silicon nitride film. The method for manufacturing a semiconductor device according to claim 4 or 5, wherein 7. An insulating film is formed on a gate electrode formed on a semiconductor substrate, and a contact plug is formed by forming a conductive film in a first contact hole formed in a predetermined region of the insulating film. , Interlayer insulation on the contact plug
A method of manufacturing a semiconductor device in which a film is formed and a second contact hole is formed in a predetermined region of the interlayer insulating film , wherein a process of exposing a side wall of the contact plug is performed at a predetermined position. Forming a first silicon nitride film for stopping, exposing a sidewall of the contact plug, and forming a sidewall made of at least a second silicon nitride film on a sidewall of the contact plug. Yes, and the second configuration by said side walls
A method for manufacturing a semiconductor device, wherein etching for forming a tact hole is stopped . 8. The semiconductor device according to claim 7, wherein the sidewall is made of the first and second silicon nitride films.
13. The semiconductor device according to claim 1. 9. The step of exposing the side wall of the contact plug includes forming the conductive film in the first contact hole, and etching back the conductive film to form the first contact hole. 9. The method of manufacturing a semiconductor device according to claim 7, further comprising: forming the contact plug therein; and etching back the insulating film to expose sidewalls of the contact plug. . 10. The step of forming the sidewall includes the step of forming the silicon nitride film so as to cover the insulating film and the contact plug, and the step of etching back the silicon nitride film to form a sidewall of the contact plug. 10. The method of manufacturing a semiconductor device according to claim 7, further comprising the step of forming the sidewall.