Method for forming a dielectric-constant-enchanced capacitor

Details Method for forming a dielectric-constant-enchanced capacitor Method for forming a dielectric-constant-enchanced capacitor

2001-05-29

2003-11-04

Arbes, Carl J. (Department: 3729)

Metal working

Electric condenser making

C029S830000, C029S831000, C029S846000

Reexamination Certificate

active

06640403

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is for the fabrication of a dielectric-constant-enhanced film, and a method of forming a capacitor of high dielectric constant.
2. Description of the Prior Art
High density dynamic random access memory (DRAM) requires using material with high dielectric constant (&egr;) for adequate electrical charge storage in its size-limited capacitor unit. After the currently-in-use material, such as SiN (&egr;~7), the next manufacturable high-dielectric-constant material would be tantalum oxide which gives a dielectric constant of about 25 for 100 Å thick film in metal-insulator-metal (MIM) capacitor structure.
The methods for forming a thin film of tantalum oxide include a sputtering method, a chemical vapor deposition method, and an anodic oxide method for tantalum film. From these methods, the chemical vapor deposition method is superior to other methods in its conformality and thus in its production worthiness.
When tantalum oxide film is integrated as a metal-insulator-semiconductor (MIS) capacitor in DRAM, it gives an effective dielectric constant less than 14 for 100 Å films on silicon bottom electrode. This only gives improvement less than 30%, reducing the equivalent silicon oxide thickness from 40 to 28 angstroms. 30% improvement from tantalum oxide is useful for the very next generation technology after SiN era, but not good enough to last for the next two generation technology.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method is provided for forming a capacitor device using (Ta
2
O
5
)
1−x
(TiO
2
)
x
thin film, wherein 0.05≦x≦0.15. This (Ta
2
O
5
)
1−x
(TiO
2
)
x
film substantially increases dielectric constant, reduces leakage current and increases the integrity of integrated circuit. The dielectric constant is greatly improved by a factor of 2 to 3.5 when tantalum oxide is mixed with titanium oxide. The leakage current of this new material can be controlled to meet the requirement for DRAM cell by appropriate thermal treatment. This invention of dielectric-constant-enhanced thin film would prolong the usage of tantalum oxide based dielectric films in DRAM industry to 0.13 &mgr;m technology and beyond.
In one embodiment, one thin silicon nitride layer and one (Ta
2
O
5
)
1−x
(TiO
2
)
x
film with 0.05≦x≦0.15 are formed on the bottom electrode. After the (Ta
2
O
5
)
1−x
(TiO
2
)
x
film is deposited, the treatments that can reduce the impurities and oxygen vacancies to reduce leakage current comprise the following techniques: plasma treatment, remote plasma treatment, rapid thermal process, UV/O
3
treatment and furnace treatment. The deposition of a metal layer on top of the thermally treated (Ta
2
O
5
)
1−x
(TiO
2
)
x
film, by physical vapor deposition or chemical vapor deposition, completes the method of the present invention.


REFERENCES:
patent: 4437139 (1984-03-01), Howard
patent: 5444006 (1995-08-01), Han et al.
patent: 5786248 (1998-07-01), Schuegraf
patent: 5835677 (1998-11-01), Li et al.
patent: 5861675 (1999-01-01), Sasaki et al.
patent: 6303972 (2001-10-01), Agarwal

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