JPH0590531A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a semiconductor device and a method of manufacturing the same, which has a structure in which a capacitor capacitance is increased without inhibiting high integration of a stack type semiconductor memory. A semiconductor device having a capacitor formed on a semiconductor substrate 1, wherein the capacitor is a continuous capacitor insulating film 11 having a plurality of turns and a first electrode arranged on both surfaces in contact with the capacitor insulating film 11. The semiconductor device is composed of 10 and the second electrode 12. In addition, a first spacer film and a second spacer film are deposited in this order on the semiconductor substrate 1, or a plurality of double films in which a first type spacer film and a second spacer film are laminated in this order are set. Stack
A capacitor having the above structure is formed by a manufacturing process for processing these films.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a capacitor structure for highly integrating a stack type semiconductor memory and a method of realizing the capacitor structure.

[0002]

2. Description of the Related Art FIGS. 6 (a) to 6 (c) are sectional views in order of steps showing a conventional example, in which 31 is a semiconductor substrate, 32 is a field oxide film,
33 is a gate oxide film, 34 is a gate electrode, 35 is a source, 36 is a drain, 37 is an insulating film, 37a is a contact window, 40 is a lower electrode, 41 is a capacitor insulating film, and 42 is an upper electrode.

A conventional example will be described below with reference to these drawings. See FIG. 6A. A field oxide film 32, a gate oxide film 33, and a gate electrode 34 are formed on a Si substrate which will be a semiconductor substrate 31.

Impurities are ion-implanted into the Si substrate 31 using the gate electrode 34 as a mask to form a source 35 and a drain 36. After forming the insulating film 7 on the entire surface, the insulating film 7 is etched using a mask (not shown) to form a contact window 37a in the source region.

Referring to FIG. 6B, after depositing a poly-Si film on the entire surface, it is etched to form a lower electrode 40 connected to the source 35.

Referring to FIG. 6C, an insulating film is deposited on the entire surface to form a capacitor insulating film 41. Then, a poly-Si film is deposited on the entire surface to form the upper electrode 42.

In this way, a capacitor connected to the source 35 is formed. Since this capacitor is formed substantially parallel to the main surface of the Si substrate, in order to increase the capacitance of the capacitor, a large area in the element area must be spent for the electrode, and high integration is achieved. Therefore, reducing the element size inevitably reduces the capacitance of the capacitor.

Therefore, in the conventional method, when the degree of integration is increased, the capacitance of the capacitor is reduced and the reliability of the semiconductor memory is deteriorated.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a capacitor structure having a much larger capacitor capacitance than the conventional one, even though the area occupied by the element regions is the same, and a method of implementing the structure. To aim.

[0010]

1 (a) and 1 (b) are sectional views showing an embodiment of a semiconductor device according to the present invention, and FIGS. 2 (a) to 2 (c).
3 is a sectional view showing the first embodiment in the order of steps (No. 1), FIG.
(d) and (e) are process order cross-sectional views showing the first embodiment (No. 2), and FIGS. 4A to 4C are process order cross-sectional views showing the second embodiment (No. 1), FIGS. 5D and 5E are sectional views (No. 2) in order of processes, showing the second embodiment.

The above-mentioned problem is a semiconductor device having a capacitor formed on the semiconductor substrate 1, wherein the capacitor is a continuous capacitor insulating film 11 having a plurality of turns.
And a first layer arranged on both sides in contact with the capacitor insulating film 11.
This is solved by a semiconductor device consisting of the electrode 10 and the second electrode 12.

Further, a step of depositing a first spacer film 8 and a second spacer film 9 in this order on the insulating film 7 formed on the semiconductor substrate 1, and a contact on the second spacer film 9. A contact window 9a which exposes the surface of the semiconductor substrate 1 by forming a mask having an opening for forming a window and etching the second spacer film 9, the first spacer film 8 and the insulating film 7 through the opening And the contact window 9a
The first spacer film 8 in the inside is selectively isotropically etched to partially expose the back surface of the second spacer film 9 and the insulating film 7.
A step of exposing a part of the surface, and the second spacer film 9
A first metal film which is continuous from the front surface to the side surface, the back surface, the side surface of the first spacer film 8, the surface of the insulating film 7 and the surface of the semiconductor substrate 1 is formed and patterned to form the first electrode 10 And the second spacer film 9 and the first spacer film 8 are sequentially removed by etching to form a part of the surface of the insulating film 7 of the first electrode 10 and the semiconductor substrate 1. A step of exposing the entire surface except the contacting portion, a step of forming a capacitor insulating film 11 on the exposed entire surface of the first electrode 10, and a step of depositing a second metal film on the capacitor insulating film 11 And a step of forming a second electrode 12, and a method of manufacturing a semiconductor device in which a capacitor composed of the first electrode 10, the capacitor insulating film 11, and the second electrode 12 is formed on the semiconductor substrate 1. Will be solved by.

Further, a plurality of sets of double films in which the first type spacer films 81, 82 and the second type spacer films 91, 92 are laminated in this order on the insulating film 7 formed on the semiconductor substrate 1 are laminated. And a mask having an opening for forming a contact window is formed on the uppermost second type spacer film 92, and the second type spacer films 91 and 92 and the first type spacer film are formed through the opening. 81,
82 and the step of etching the insulating film 7 to form the contact window 9a exposing the surface of the semiconductor substrate 1, and the first type spacer films 81 and 82 in the contact window 9a are selectively isotropic. A step of etching to expose a part of the surface and the back surface of the second type spacer film 92 and a part of the surface of the insulating film 7; Side surfaces of the first type spacer films 81 and 82 and the insulating film 7
A first metal film is formed continuously over the surface and the surface of the semiconductor substrate 1 and is patterned to form a first electrode 10
And removing the second type spacer films 91, 92 and the first type spacer films 81, 82 by etching to remove a part of the surface of the insulating film 7 of the first electrode 10 and The semiconductor substrate 1
By exposing the entire surface except the portion in contact with the capacitor, forming a capacitor insulating film 11 on the exposed entire surface of the first electrode 10, and depositing a second metal film on the capacitor insulating film 11. Forming a second electrode 12 on the semiconductor substrate 1, the first electrode 10 and the capacitor insulating film.
11. It is solved by a method of manufacturing a semiconductor device in which a capacitor composed of the second electrode 12 is formed.

[0014]

[Function] A capacitor composed of a continuous capacitor insulating film 11 having a plurality of turns and a first electrode 10 and a second electrode 12 arranged on both surfaces in contact with the capacitor insulating film 11
It is possible to have a much larger capacitor capacity than a substantially planar capacitor in which the area occupied by the element region is equal.

The capacitor having such a shape uses the first spacer film 8 and the second spacer film 9 sequentially formed on the insulating film 7 formed on the semiconductor substrate 1 as described above. Can be realized by

In the capacitor having such a shape, first type spacer films 81 and 82 and second type spacer films 91 and 92 are laminated in this order on the insulating film 7 formed on the semiconductor substrate 1. This can be realized by stacking a plurality of sets of double films and using the spacer films thereof as described above.

[0017]

1 (a) and 1 (b) are sectional views showing an embodiment of a semiconductor device according to the present invention, in which 1 is a semiconductor substrate, 2 is a field oxide film, 3 is a gate oxide film, and 4 is a gate electrode. , 5 is a source, 6 is a drain, 7 is an insulating film, 10 is a lower electrode, 11
Is a capacitor insulating film, and 12 is an upper electrode.

FIGS. 2 (a) to 2 (c) and FIGS. 3 (d) and 3 (e) show the first
Sectional views in order of steps (No. 1) and (No. 2)
The process for realizing the structure of Fig. 1 (a) is shown. Less than,
The steps of the first embodiment will be described with reference to these drawings.

Referring to FIG. 2 (a), a field oxide film having a thickness of 4000 to 5000 Å 2, a gate oxide film 3 having a thickness of 150 to 200 Å 3, is formed on a Si substrate which is a semiconductor substrate 1.
A gate electrode 4 of poly-Si is formed.

Impurities are ion-implanted into the Si substrate 1 using the gate electrode 4 as a mask to form a source 5 and a drain 6. The thickness is 1000Å as the insulating film 7 on the entire surface by the CVD method
Thickness of 1500 as the first spacer film 8 of the silicon oxide film of
A silicon nitride film having a thickness of up to 3000 Å and a silicon oxide film having a thickness of 500 to 1000 Å are deposited in this order as the second spacer film 9.

The source 5 is exposed by anisotropically dry-etching the second spacer film 9, the first spacer film 8 and the insulating film 7 using a resist mask (not shown) having an opening on the source 5. The contact window 9a is formed.

Referring to FIG. 2 (b), the first spacer film (silicon nitride film) 8 inside the contact window 9a is selectively and isotropically wet-etched by boiling phosphoric acid to form a back surface of the second spacer film 9. A part and a part of the surface of the insulating film 7 are exposed. The lateral distance between the exposed rear surface of the second spacer film 9 and the exposed surface of the insulating film 7 can be adjusted by selecting the etching time.

Referring to FIG. 2C, a poly-Si film having a thickness of 500 to 1000 Å is deposited on the entire surface by the CVD method. The poly-Si film is a film continuous from the surface of the second spacer film 9 to the side surface and the back surface thereof, the side surface of the first spacer film 8, the insulating film 7 surface and the Si substrate 1 surface.

The lower electrode 10 is formed by etching and patterning this poly-Si film. Referring to FIG. 3D, the second spacer film (silicon oxide film) 9 is removed by wet etching with a hydrofluoric acid-based etchant. Then,
The first spacer film (silicon nitride film) 8 is removed by wet etching with boiling phosphoric acid.

Referring to FIG. 3E, a silicon nitride film having a thickness of 50 to 150 Å is deposited on the entire surface by a CVD method to form a capacitor insulating film 11. The capacitor insulating film 11 is a film that continuously covers the surface of the insulating film 7 and the surface of the lower electrode 10, and has a shape having a plurality of folds.

Then, a capacitor insulating film is formed by the CVD method.
11 Deposit a 500 Å thick poly-Si film on the entire surface and
To form. This poly-Si film fills the gap between the folded capacitor insulating films 11.

In this way, a capacitor composed of the lower electrode 10 connected to the source 5, the capacitor insulating film 11, and the upper electrode 12 is formed. Next, a second embodiment will be described.

FIGS. 4 (a) to 4 (c) and FIGS. 5 (d) and 5 (e) show the second
Sectional views in order of steps (No. 1) and (No. 2)
The process for realizing the structure of Fig. 1 (b) is shown. Less than,
The steps of the second embodiment will be described with reference to these drawings.

Referring to FIG. 4 (a), a field oxide film having a thickness of 4000 to 5000 Å 2, a gate oxide film 3 having a thickness of 150 to 200 Å 3 is formed on a Si substrate which is a semiconductor substrate 1.
A gate electrode 4 of poly-Si is formed.

Impurities are ion-implanted into the Si substrate 1 using the gate electrode 4 as a mask to form a source 5 and a drain 6. The thickness is 1000Å as the insulating film 7 on the entire surface by the CVD method
Thickness of the silicon oxide film of the first type spacer film 81
00-3000Å silicon nitride film, second-type spacer film 91 as silicon oxide film with a thickness of 500-1000Å, and the first
A silicon nitride film having a thickness of 1500 to 3000 Å is deposited as a seed spacer film 82, and a silicon oxide film having a thickness of 500 to 1000 Å is deposited as a second spacer film 92 in this order.

By using a resist mask (not shown) having an opening on the source 5, the second type spacer films 91, 92, first
The seed spacer films 81, 82 and the insulating film 7 are anisotropically dry-etched to form a contact window 9a exposing the source 5.

Referring to FIG. 4 (b), the first type spacer films (silicon nitride films) 81 and 82 inside the contact window 9a are selectively and isotropically wet-etched with boiling phosphoric acid to form the second type spacers. Part of the back surface of the film 92, part of the front surface of the second type spacer film 91, part of the back surface, and part of the surface of the insulating film 7 are exposed. The lateral distance between the exposed portions of the front and back surfaces of the second type spacer films 91 and 92 and the exposed surface of the insulating film 7 can be adjusted by selecting the etching time.

Referring to FIG. 4C, a poly-Si film having a thickness of 500 to 1000 Å is deposited on the entire surface by the CVD method. The poly-Si film is a film that is continuous from the surfaces of the second type spacer films 91 and 92 to the side surfaces and the back surface thereof, the side surfaces of the first type spacer films 81 and 82, and the surface of the insulating film 7 and the surface of the Si substrate 1.

The lower electrode 10 is formed by etching and patterning this poly-Si film. See FIG. 5D. The second type spacer film (silicon oxide film) 92 is removed by wet etching with a hydrofluoric acid-based etchant. Subsequently, the first type spacer film (silicon nitride film) 82 is removed by wet etching with boiling phosphoric acid. Subsequently, the second type spacer film (silicon oxide film) 91 is removed by wet etching with a hydrofluoric acid-based etchant. Subsequently, the first type spacer film (silicon nitride film) 81 is removed by wet etching with boiling phosphoric acid.

Referring to FIG. 5 (e), a silicon nitride film having a thickness of 50 to 150 Å is deposited on the entire surface by the CVD method to form a capacitor insulating film 11. The capacitor insulating film 11 is a film that continuously covers the surface of the insulating film 7 and the surface of the lower electrode 10, and has a shape having a plurality of folds.

Then, a capacitor insulating film is formed by the CVD method.
11 Deposit a 500 Å thick poly-Si film on the entire surface and
To form. This poly-Si film fills the gap between the folded capacitor insulating films 11.

In this way, a capacitor composed of the lower electrode 10 connected to the source 5, the capacitor insulating film 11, and the upper electrode 12 is formed. The second embodiment is an example in which the capacitance of the capacitor can be made larger than that of the first embodiment. First
By stacking three or more pairs of double films in which the first type spacer film and the second type spacer film are stacked, the capacitance of the capacitor can be further increased as compared with the second embodiment.

The area of the capacitor insulating film 11 is several times as large as the area of the occupied element region, and it is possible to have a much larger capacitor capacitance than the conventional planar capacitor.

[0039]

As described above, according to the present invention,
It is possible to increase the capacitance of the capacitor without inhibiting the high integration of the stacked semiconductor memory.

The present invention contributes to high integration of the stack type semiconductor memory.

[Brief description of drawings]

1A and 1B are cross-sectional views showing an embodiment of a semiconductor device according to the present invention.

2A to 2C are sectional views (No. 1) in the process order showing the first embodiment.

3 (d) and 3 (e) are process order cross-sectional views (No. 2) showing the first embodiment.

4A to 4C are sectional views (first) in the process order showing the second embodiment.

5 (d) and 5 (e) are process sectional views (2) showing the second embodiment.

6A to 6C are cross-sectional views in order of the processes, showing a conventional example.

[Explanation of symbols]

 1 is a semiconductor substrate, Si substrate 2 is a field oxide film 3, is a gate oxide film 4, is a gate electrode 5, is a source 6, is a drain 7, is an insulating film, and is a silicon oxide film 8 is a first spacer film, and is silicon. The nitride film 9 is the second spacer film, the silicon oxide film 9a is the contact window 10 is the first electrode and the lower electrode, the poly-Si film 11 is the capacitor insulating film, and the silicon nitride film 12 is the second electrode. Electrode and upper electrode, poly-Si film 31 is a semiconductor substrate, Si substrate 32 is field oxide film 33, gate oxide film 34 is gate electrode 35, source 36 is drain 37, insulating film 37a is contact window 40 Is a lower electrode 41 is a capacitor insulating film 42 is an upper electrode 81, 82 is a first type spacer film and is a silicon nitride film 91, 92 is a second type spacer film is a silicon oxide film.

Claims (3)

[Claims] 1. A semiconductor device having a capacitor formed on a semiconductor substrate (1), the capacitor being in contact with a continuous capacitor insulating film (11) having a plurality of folds and the capacitor insulating film (11). A semiconductor device comprising a first electrode (10) and a second electrode (12) disposed on both surfaces of the semiconductor device. 2. An insulating film formed on a semiconductor substrate (1)
(7) First spacer film (8) and second spacer film on top
(9) is deposited in this order, a mask having an opening for forming a contact window is formed on the second spacer film (9), and the second spacer film (9) and the mask are formed through the opening. A step of etching the first spacer film (8) and the insulating film (7) to form a contact window (9a) exposing the surface of the semiconductor substrate (1); and a step of forming the contact window (9a) in the contact window (9a). A step of selectively isotropically etching the first spacer film (8) to expose a part of the back surface of the second spacer film (9) and a part of the surface of the insulating film (7); A first metal film which is continuous from the surface of the second spacer film (9) to its side surface, the back surface thereof, the side surface of the first spacer film (8), the surface of the insulating film (7) and the surface of the semiconductor substrate (1). And then patterning it to form the first electrode (10), and the second spacer film (9) and the first spacer film (8) are sequentially removed by etching. Insulating the first electrode (10) Enmaku
(7) A step of exposing the entire surface except a part of the surface and a portion in contact with the semiconductor substrate (1), and a capacitor insulating film (11) on the exposed entire surface of the first electrode (10)
And a step of forming a second electrode (12) by depositing a second metal film on the capacitor insulating film (11), and forming a second electrode (12) on the semiconductor substrate (1). A method of manufacturing a semiconductor device, which comprises forming a capacitor composed of the first electrode (10), the capacitor insulating film (11) and the second electrode (12). 3. An insulating film formed on a semiconductor substrate (1)
(7) A step of laminating a plurality of pairs of double films in which the first type spacer film (81, 82) and the second type spacer film (91, 92) are laminated in this order, and the second uppermost layer. A mask having an opening for forming a contact window is formed on the first type spacer film (92), and the second type spacer film (91, 92) and the first type spacer film (81, 82) are formed through the opening.
And a step of etching the insulating film (7) to form a contact window (9a) exposing the surface of the semiconductor substrate (1); and the first type spacer film (81, 81) in the contact window (9a). 82)
Selectively isotropically etching the second type spacer film (92) to expose a part of the front and back surfaces of the second type spacer film (92) and a part of the front surface of the insulating film (7), and a second type spacer. From the surface of the film (91, 92) to the side surface, the back surface, the side surface of the first type spacer film (81, 82) and the insulating film
(7) A step of forming a first metal film continuous over the surface and the surface of the semiconductor substrate (1) and patterning the first metal film to form a first electrode (10); 91, 92) and the spacer film of the first type
(81, 82) is removed by etching to expose the entire surface of the first electrode (10) except a part of the surface of the insulating film (7) and a part in contact with the semiconductor substrate (1), A capacitor insulating film (11) is formed on the entire exposed surface of the first electrode (10).
And a step of forming a second electrode (12) by depositing a second metal film on the capacitor insulating film (11), and forming a second electrode (12) on the semiconductor substrate (1). A method of manufacturing a semiconductor device, comprising forming a capacitor composed of the first electrode (10), the capacitor insulating film (11) and the second electrode (12).