Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2001-01-18
2001-08-07
Tsai, Jey (Department: 2812)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C438S255000
Reexamination Certificate
active
06271085
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming a bottom electrode of a storage capacitor, and more particularly to a method of forming a bottom electrode of a storage capacitor in a semiconductor memory device such as a dynamic random access memory, wherein the storage capacitor has an increased capacity in unit area and shows a reduced leakage of current.
FIGS. 1A and 1B
are fragmentary cross sectional elevation views illustrative of bottom electrodes of storage capacitors over base insulating films in sequential steps involved in a conventional method.
With reference to
FIG. 1A
, an etching stopper film
62
is formed over an upper surface of a base insulating film
61
. A hole is formed in a base insulating film
61
. A polysilicon contact plug
63
is filled into the hole of the base insulating film
61
. A silicon electrode is formed over the etching stopper film
62
over the base insulating film
61
, wherein a bottom of the silicon electrode is in contact with the top of the polysilicon contact plug
63
. Further, hemi-spherical grains are formed on a surface of the silicon electrode to form a silicon stack electrode
64
.
With reference to
FIG. 1B
, the silicon stack electrode
64
is exposed to a WF
6
gas to substitute the hemi-spherical grains into tungsten W, whereby a tungsten stack electrode
94
is formed.
The above conventional method has the following disadvantages. Available metal is limited into tungsten which may shows a substitutional reaction with silicon (3Si+2WF
6
→2W+3SiF
4
). This reaction causes variation in volume, whereby the surface of the stack electrode
94
is deformed. Even illustration is not omitted, a dielectric film is formed on the deformed surface of the stack electrode
94
. The deformed surface of the stack electrode
94
increases a leakage of current of the dielectric film.
In the above circumstances, it had been required to develop a novel method of forming a metal bottom electrode of a storage capacitor in a semiconductor memory device free from the above problem.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a novel method of forming a metal bottom electrode of a storage capacitor in a semiconductor memory device free from the above problems.
It is a further object of the present invention to provide a novel method of forming a metal bottom electrode of a storage capacitor in a semiconductor memory device, wherein the storage capacitor has a large capacity in a unit area.
It is a still further object of the present invention to provide a novel method of forming a metal bottom electrode of a storage capacitor in a semiconductor memory device, wherein the storage capacitor shows a reduced leakage of current.
It is yet a further object of the present invention to provide a novel method of forming a metal bottom electrode of a storage capacitor in a semiconductor memory device, wherein the metal bottom electrode has a reduced resistivity.
The present invention provides a method of forming an electrode, comprising the steps of: forming a dummy electrode having an uneven side face; forming a template insulating film which completely buries the dummy electrode; removing the dummy electrode with leaving the template insulating film so as to form a hole in the template insulating film, wherein a shape of the uneven side face of the dummy electrode as removed is transferred to an inside wall of the hole; filling a metal film into the hole of the template insulating film, wherein the shape of the uneven inside wall of the hole is transferred to a side face of the metal film; and removing the template insulating film to form a metal electrode with an uneven side face.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.
REFERENCES:
patent: 5438011 (1995-08-01), Blalock et al.
patent: 5556802 (1996-09-01), Bakeman, Jr. et al.
NEC Corporation
Tsai Jey
Young & Thompson
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