Semiconductor device manufacturing: process – Making passive device – Stacked capacitor
Reexamination Certificate
1999-03-04
2003-04-08
Chaudhuri, Olik (Department: 2814)
Semiconductor device manufacturing: process
Making passive device
Stacked capacitor
C438S397000, C365S145000, C365S149000, C361S321400
Reexamination Certificate
active
06544857
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a dielectric capacitor manufacturing method and a semiconductor storage device manufacturing method especially suitable for use in fabrication of a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystal structure and fabrication of a semiconductor storage device having such a dielectric capacitor.
2. Description of the Related Art
Recently, the area of a memory cell was rapidly reduced along with an increase in storage capacitance of semiconductor storage devices. Concurrently, in a capacitor forming a memory cell, efforts are made to ensure a required charge capacitance by employing a three-dimensional complex structure. Under these circumstances, in the attempt of improving the production yield and reducing the steps of the manufacturing process by simplification of the construction, researches are made toward employment of a dielectric capacitor simplified in construction by using a dielectric film with a high dielectric constant. Known as a dielectric film with a high capacitor is one having a perovskite type crystalline structure and made of a polycrystalline oxide with a grain size of 20 to 300 nm, approximately.
A conventional technique for making a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystalline structure was configured to first make a dielectric film on a lower electrode in form of a film on a substrate, then anneal the dielectric film to crystallize it, further make an upper electrode on the crystallized dielectric film, and pattern the upper electrode, dielectric film and lower electrode into the form of a dielectric capacitor by etching, using reactive ion etching (RIE) or ion milling.
However, in the case where a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystalline structure was made by the conventional technique, there was the problem that the characteristics of the dielectric capacitor after treatment deteriorated significantly due to etching of a certain element or shortage of oxygen along the treated surface of the dielectric film during etching by RIE or ion milling. Especially when the area of the dielectric capacitor was reduced below 10 &mgr;m
2
, particularly, several &mgr;m
2
, along with large-scaling of semiconductor memory, there was a tendency toward an increase of the area occupied by individual crystal grains in the dielectric film relative to the entire area of the capacitor, hence a relative increase of influences from damages of individual crystal grains belonging to side wall portions of the capacitor during etching process, an increase of deterioration of characteristics of the dielectric capacitor.
Moreover, in the case where a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystalline structure was made by the conventional technique, there was a tendency toward an increase of the leak current of the dielectric capacitor due to deposition of a certain metal or generation of a conductive oxide on side walls of the dielectric capacitor during the etching process or the subsequent annealing process especially in large-capacity semiconductor memory in which the area of the dielectric capacitor is reduced below 10 &mgr;m
2
, particularly, several &mgr;m
2
, and it was a serious reason adversely affecting the reliability.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a dielectric capacitor manufacturing method and a semiconductor storage device manufacturing method capable of realizing a dielectric capacitor exhibiting good characteristics even when the area of dielectric capacitor is reduced upon manufacturing the dielectric capacitor using a dielectric film with a perovskite type crystalline structure and a semiconductor storage device including the dielectric capacitor.
Another object of the invention is to provide a dielectric capacitor manufacturing method and a semiconductor storage device manufacturing method capable of realizing a dielectric capacitor having exhibiting good characteristics and improving the reliability even when the area of the dielectric capacitor is reduced upon manufacturing the dielectric capacitor using a dielectric film with a perovskite type crystalline structure and a semiconductor storage device including the dielectric capacitor.
According to the first aspect of the invention, there is provided a method for manufacturing a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystalline structure, comprising the steps of:
making a lower electrode;
making on the lower electrode a precursor film having as its major component an amorphous phase or a fluorite phase of components elements of the dielectric material;
making an upper electrode on the precursor patterning at least the upper electrode and the precursor film into the form of the dielectric capacitor by etching; and
annealing the precursor film patterned into the form of the dielectric capacitor to change the amorphous phase or the fluorite phase to a crystal phase of a perovskite type crystalline structure and obtain the dielectric film.
According to the second aspect of the invention, there is provided a method for manufacturing a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystalline structure, comprising the steps of:
making a lower electrode;
making on the lower electrode a precursor film having as its major component an amorphous phase or a fluorite phase of components elements of the dielectric material;
making an upper electrode on the precursor film;
patterning the upper electrode and the precursor film into the form of the dielectric capacitor by etching;
making a protective coat which covers side walls of the upper electrode and the precursor film patterned into the form of the dielectric capacitor; and
annealing the precursor film patterned into the form of the dielectric capacitor and having the protective coat on the side walls to change the amorphous phase or the fluorite phase to a crystal phase of a perovskite type crystalline structure and obtain the dielectric film.
According to the third aspect of the invention, there is provided a method for manufacturing a semiconductor storage device having a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystalline structure, comprising the steps of:
making a lower electrode of the dielectric capacitor;
making on the lower electrode a precursor film having as its major component an amorphous phase or a fluorite phase of components elements of the dielectric material;
making an upper electrode on the precursor film;
patterning at least the upper electrode and the precursor film into the form of the dielectric capacitor by etching; and
annealing the precursor film patterned into the form of the dielectric capacitor to change the amorphous phase or the fluorite phase to a crystal phase of a perovskite type crystalline structure and obtain the dielectric film.
According to the fourth aspect of the invention, there is provided a method for manufacturing a semiconductor storage device having a dielectric capacitor using a dielectric film made of a dielectric material with a perovskite type crystalline structure, comprising the steps of:
making a lower electrode of the dielectric capacitor;
making on the lower electrode a precursor film having as its major component an amorphous phase or a fluorite phase of components elements of the dielectric material;
making an upper electrode on the precursor film;
patterning the upper electrode and the precursor film into the form of the dielectric capacitor by etching;
making a protective coat which covers side walls of the upper electrode and the precursor film patterned into the form of the dielectric capacitor; and
annealing the precursor film patterned into the form of the di
Ami Takaaki
Hironaka Katsuyuki
Isobe Chiharu
Sugiyama Masataka
Chaudhuri Olik
Rao Shirinivas H.
Sonnenschein Nath & Rosenthal
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