Method of manufacturing a capacitor in a semiconductor device

Details Method of manufacturing a capacitor in a semiconductor device Method of manufacturing a capacitor in a semiconductor device

2000-09-11

2001-10-16

Lebentritt, Michael (Department: 2824)

Semiconductor device manufacturing: process

Making field effect device having pair of active regions...

Having insulated gate

C438S254000, C438S197000

Reexamination Certificate

active

06303427

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to a method of manufacturing a capacitor in a semiconductor device, and more particularly to, a method of manufacturing a capacitor in a semiconductor device which can prevent oxidization of the surface of an underlying electrode to improve the characteristic of the leak current of a Ta
2
O
5
capacitor, upon a thermal treatment process performed after Ta
2
O
5
is deposited in order to form a dielectric film, in a Ta
2
O
5
capacitor of a MIM (Metal Insulator Metal) structure using tungsten (W) as an underlying electrode.
2. Description of the Prior Art
Generally, when manufacturing a Ta
2
O
5
capacitor in a memory device, if metal materials such as Tungsten are used as underlying electrode materials, the work function of the metal materials with poly-silicon is large. Thus, the thickness of the effective oxide film Tox can be reduced and thus the leak current in the thickness of the same effective oxide film can also be reduced. Further, the value of &Dgr; C depending on the bias voltage is small. As a Ta
2
O
5
dielectric film lacks oxygen in the film formed by Ta
2
O
5
deposition process and also contains impurities such as carbon or hydrogen etc., in order to secure the dielectric characteristic of the Ta
2
O
5
capacitor, oxygen must be flowed into it and a subsequent process for removing impurities must be performed after the Ta
2
O
5
deposition is completed.
This subsequent process is mainly thermally performed under oxygen atmosphere at a higher temperature, thus securing the dielectric characteristic of a Ta
2
O
5
dielectric film. However, if the temperature of the thermal process is too high or the time of the thermal treatment is too long, upon thermal treatment process, the surface of the underlying tungsten electrode is oxidized to form a WO
3
film. The WO
3
film has the dielectric constant of about 42, which is higher than that of Ta
2
O
5
dielectric film having about 25. However, when creating the WO
3
film, there is a possibility that oxygen within the Ta
2
O
5
dielectric film can be diffused into the underlying tungsten electrode. Also, due to the difference of the thermal expansion coefficient with the Ta
2
O
5
dielectric film, there is a problem that the characteristic of the leak current of the Ta
2
O
5
capacitor becomes degraded since a phenomenon of film lifting of the film is generated.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method of manufacturing a capacitor in a semiconductor device which can prevent oxidization of the surface of an underlying electrode to improve the characteristic of the leak current of a Ta
2
O
5
capacitor, upon a thermal treatment process performed after Ta
2
O
5
is deposited in order to form a dielectric film, in a Ta
2
O
5
capacitor of a MIM (Metal Insulator Metal) structure using tungsten (W) as an underlying electrode.
In order to accomplish the object, a method of manufacturing a capacitor in a semiconductor device according to the present invention is characterized in that it comprises the steps of forming an underlying tungsten electrode on a substrate in which an underlying structure is formed; forming a WO
3
film on the surface of the underlying tungsten electrode; forming a Ta
2
O
5
dielectric film on the WO
3
film; and forming an upper electrode on the Ta
2
O
5
dielectric film.


REFERENCES:
patent: 4448493 (1984-05-01), Matsudiara et al.
patent: 5189503 (1993-02-01), Suguro et al.
patent: 5219778 (1993-06-01), Dennison et al.
patent: 5298436 (1994-03-01), Radosevich et al.
patent: 5405796 (1995-04-01), Jones
patent: 5442235 (1995-08-01), Parrillo et al.
patent: 5516725 (1996-05-01), Chang et al.
patent: 5552340 (1996-09-01), Lee et al.

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