Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
1999-09-10
2001-03-27
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S250000, C438S253000, C438S393000, C438S396000
Reexamination Certificate
active
06207489
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor memory device, and more particularly, to a method for manufacturing a capacitor having a dielectric film formed of a tantalum oxide film.
2. Description of the Related Art
As the integration degree of a dynamic random access memory (DRAM) increases, methods of increasing the effective area of a capacitor, methods of reducing the thickness of a dielectric film, and methods of increasing the dielectric constant of the dielectric film are used in order to increase the amount of charge accumulated in a restricted cell area.
For example, in a stacked structure comprising a silicon nitride film and a silicon oxide film used as the dielectric film of current highly integrated memory devices, the effective electrical thickness is reduced by physically reducing the thickness of the stacked structure. The limits of the effective electrical thickness of the stacked structure comprising the silicon nitride film and the silicon oxide film are considered to be about 40 Å. A dielectric film having an effective electrical thickness of less than
40
A is difficult to deploy in an operating device due to the large leakage current experienced at such thicknesses.
In order to overcome the limits of the stacked silicon nitride and silicon oxide films, dielectric materials with higher dielectric constants are being employed. For example, a tantalum oxide film has a dielectric constant of about 24, which is larger than the dielectric constant of a silicon nitride film, which is about 7. Moreover, ferroelectric materials with dielectric constants of no less than several hundreds are being employed.
The appropriateness of introducing a new dielectric material should be determined based on its suitability for use in conventional processes, probability of stable manufacturing apparatuses, mass productivity, economical efficiency, and stableness of the operation of the device. The tantalum oxide film is known to be the material which most closely satisfies the above requirements.
The electrical characteristics of the tantalum oxide film depend considerably on the processing conditions. In the present invention, optimal processing conditions are described for forming the tantalum oxide film for use as a dielectric film.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for manufacturing a capacitor of a semiconductor memory device in which a tantalum oxide film is formed under optimal processing conditions to thereby achieve optimal electrical characteristics for the tantalum oxide film when Io used as a dielectric film of the capacitor.
Accordingly, to achieve the above and other objects, the present invention provides a method for manufacturing a capacitor of a semiconductor memory device where a lower electrode is formed that is electrically connected to an active region of a semiconductor substrate. A pre-treatment film, including a component selected from a group consisting of silicon oxide, silicon nitride, and combinations thereof, is formed on the surface of the lower electrode. A dielectric film is formed on the pre-treatment film using a tantalum (Ta) precursor, with the dielectric film comprising a first dielectric layer deposited at a first temperature selected from a designated temperature range, and a second dielectric layer deposited at a second temperature different from the first temperature and selected from the same designated temperature range. A thermal treatment is thereafter performed on the dielectric film in an oxygen atmosphere.
The lower electrode is formed of one selected from a group consisting of a polysilicon film, a metal film, a metal oxide film, a metal nitride film, a metal oxynitride film and combinations thereof.
The Ta precursor is one selected from a group consisting of metal alkoxides, organic metals, metal halides, and mixtures thereof.
The pre-treatment film is formed by a rapid thermal nitridation (RTN) method, a rapid thermal oxidation (RTO) method, a chemical vapor deposition (CVD) method, or a combination thereof. The step of forming the pre-treatment film may comprise a step of supplying plasma or irradiating ultra violet (UV) radiation.
During the step of forming the dielectric film, the designated temperature range is 350 to 550° C. The second temperature may be lower than or higher than the first temperature. The dielectric film forming step is performed at a pressure of between 100 mTorr and atmospheric pressure. The forming of the dielectric film can be carried out in a single wafer type reactor or a batch type reactor, and may comprise a step of supplying plasma or irradiating ultra violet (UV) radiation.
The thermal treatment is performed at 650 to 800° C. The thermal treatment is performed in a gas atmosphere selected from a group consisting of O
2
, O
3)
or N
2
O, and mixtures thereof. The thermal treatment step may comprise a step of supplying plasma or irradiating ultra violet (UV) radiation.
After forming the pre-treatment film and before forming the dielectric film, the method may further comprise flowing the Ta precursor over the lower electrode covered with the pre-treatment film.
According to the present invention, it is possible to form a tantalum oxide film having a reduced defect density. When such a tantalum oxide film is used as a dielectric film, it is possible to improve the electrical characteristics of a capacitor. Productivity is raised by reducing the incubation time during a deposition process for forming the tantalum oxide film.
REFERENCES:
patent: 5438012 (1995-08-01), Kamiyama
patent: 5468687 (1995-11-01), Carl et al.
patent: 5688724 (1997-11-01), Yoon et al.
patent: 5837593 (1998-11-01), Park et al.
patent: 5985730 (1999-11-01), Lim
H. Shinriki and M. Nakata, “UV-O and Dry-O: Two-Step Annealed Chemical Vapor-Deposited Ta O Films for Storage Dielectrics of 64-MbDRAM's,” IEEE Transactions on Electron Devices, vol. 38, No. 3, Mar. 1991, pp. 455-462.
Hyung Yong-woo
Nam Kab-jin
Park Ki-yeon
Park Young-wook
Won Seok-jun
Bowers Charles
Jones Volentine, LLC
Samsung Electronics Co,. Ltd.
Smoot Stephen W.
LandOfFree
Method for manufacturing capacitor of semiconductor memory... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing capacitor of semiconductor memory..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing capacitor of semiconductor memory... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2520869