Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
1998-12-28
2001-04-17
Le, Vu A. (Department: 2824)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S239000, C438S253000, C438S254000, C438S260000, 43
Reexamination Certificate
active
06218231
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a technology in the field of fabricating semiconductor devices; and, more particularly, to methods for fabricating high dielectric capacitors applied to super-large-scale-integrated DRAMs and FeRAMs.
DESCRIPTION OF THE PRIOR ART
According to high integration of semiconductor memory devices such as dynamic random access memory (DRAM), the operation properties of semiconductor devices such as refresh property have been attended as a primary thing. Therefore, in order to obtain the suitable operation properties, the researches and developments for obtaining the sufficient static capacitance of capacitors have been undergoing.
Typical capacitors in the prior art using the dielectric films of nitric oxide (NO) and tantalum oxide (Ta
2
O
5
), have a bottom electrode of three-dimensional structure or a ferroelectric film with decreased thickness in order to provide the static capacitance enough to obtain their operational properties. However, the structure of the capacitors in the prior art has been faced with difficulty to apply to high integration of semiconductor devices.
Therefore, high dielectric capacitors using thin films of high dielectric materials with dielectric constant of more than 7 such as strontium titanate SrTiO
3
, (Ba,Sr)TiO
3
(hereinafter, referred to as barium strontium titanate (BST)), Pb(Zr,Ti)O
3
(hereinafter, referred to as lead zirconate titanate (PZT)) have been researched and developed in order to use as capacitors of DRAM and post-generation semiconductor memory devices in the future.
In these high dielectric capacitors, a film of platinum (Pt), ruthenium dioxide (RuO
2
), iridium (Ir), or iridium dioxide (IrO
2
) are applied as a bottom electrode with a film of diffusion barrier for preventing diffusion of polysilicon plup. As a film of diffusion barrier to a bottom electrode, a film of titanium nitride (TiN) is generally used. There are, however, drawbacks that the film of TiN is easily oxidized under oxygen atmosphere in the process for depositing high dielectric material at high temperature and in the thermal treatment process for crystallization of the high dielectric material, to form a thin film of titanium dioxide (TiO
2
) and thus to greatly decrease the properties of the dielectric.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for fabricating a high dielectric capacitor of a semiconductor device without decreasing the properties of the dielectric under oxygen atmosphere in the process of depositing a high dielectric thin film at high temperature and in the thermal treatment process for the crystallization of the dielectric.
In accordance with one embodiment of the present invention, there is provided a method for fabricating a high dielectric capacitor of a semiconductor device which comprises the steps of: forming a film of IrO
2
electrically connected to a semiconductor substrate on which a predetermined lower layer is formed; forming a film of Pt (or Ir) on the film of IrO
2
; selectively etching the films of Pt (or Ir) and IrO
2
to define a bottom electrode; forming a thin film of high dielectric material over the entire structure; and forming an upper electrode on the thin film of high dielectric material.
Using the hybrid electrode of the IrO
2
film and the Pt (or Ir) film together with properties of diffusion barrier and bottom electrode, the present invention can enhance the thermal stability of the bottom electrode and, thus, fabricate the capacitor with excellent properties through stabilization of the processes for forming the high dielectric film.
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Blakely & Sokoloff, Taylor & Zafman
Hyundai Electronics Industries Co,. Ltd.
Le Vu A.
Luu Pho
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