Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
1999-07-20
2001-10-23
Loke, Steven (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S383000, C257S371000, C257S296000
Reexamination Certificate
active
06307228
ABSTRACT:
This application is based on a Japanese Patent Application No. 9-212091 filed on Aug. 6, 1997, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a semiconductor device and its manufacture method, and more particularly to a semiconductor device with capacitors having dielectric oxide films of a perovskite crystal structure, and its manufacture method.
b) Description of the Related Art
One memory cell of a dynamic random access memory (DRAM) is made of one transistor and one capacitor. In order to give a sufficiently large capacitance with a small capacitor, it is preferable that a capacitor dielectric film has as high a dielectric constant as possible. If the dielectric film is made of ferroelectric substance, the polarizing state of the dielectric film can be memorized so that a non-volatile ferroelectric random access memory (FRAM) can be realized.
As high dielectric constant substance having a relative dielectric constant of 10 or higher, or more preferably 50 or higher, oxide having a perovskite crystal structure is known such as barium strontium titanate (BST) (BaSrTiO). As ferroelectric substance, oxides having a perovskite crystal structure are also known such as PZT (PbZrTiO) and SBT (SrBiTiO). A dielectric oxide film of a perovskite crystal structure can be formed by spin-on such as a sol-gel method, sputtering, chemical vapor deposition (CVD), and the like.
A dielectric oxide film of a perovskite crystal structure just after it is formed often takes an amorphous phase or an insufficient crystallinity, or has often insufficient oxygen compositions. In such cases, the dielectric oxide film just after the film formation cannot be used as a good dielectric oxide film unless it is processed further. It is necessary to anneal it in an oxidizing atmosphere.
Even if insufficient oxygen atoms are replenished and the film is recrystallized, the characteristics of dielectric oxide are often degraded if the film is thereafter exposed in a reducing atmosphere such as high temperature hydrogen. However, in the manufacture processes of a semiconductor device, many semiconductor films and insulating films are formed by using hydrogen containing gas. After a dielectric oxide film of a perovskite crystal structure is formed, if another film is formed using such hydrogen containing gas, the dielectric characteristics of the film may be degraded considerably.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a semiconductor device with capacitors having dielectric oxide films of a perovskite crystal structure providing a high dielectric constant.
It is another object of the present invention to provide a method of manufacturing a semiconductor device capable of forming a dielectric oxide film of a perovskite crystal structure providing a high dielectric constant and capable of fabricating semiconductor elements at a high integration density.
According to one aspect of the present invention, there is provided a semiconductor device comprising: a semiconductor substrate having a first conductivity type region and a second conductivity type region, the second conductivity type being opposite to the first conductivity type; first and second insulated gate field effect transistors respectively having first and second insulated gate electrode structures formed on the first and second conductivity type regions of the semiconductor substrate and first and second pairs of impurity doped regions of the second and first conductivity types formed in the semiconductor substrate on both sides of the first and second insulated gate electrode structures; a first insulating film formed over the semiconductor substrate and covering the first and second insulated gate field effect transistors; at least two metal plugs formed through the first insulating film and reaching at least ones of the first and second pairs of impurity doped regions of the first and second insulated gate field effect transistors; a second insulating film having an oxygen blocking function and covering the first insulating film; a lower electrode formed on the second insulating film; a dielectric oxide film having a perovskite crystal structure and formed on the lower electrode; an upper electrode formed on the dielectric oxide film to form a capacitor together with the lower electrode and the dielectric oxide film; a third insulating film formed over the semiconductor substrate and covering the capacitor; and a local interconnect extending on the third insulating film and being connected via a contact hole formed through the third insulating film between one of the metal plugs and said upper or lower electrode.
According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising the steps of: forming an insulated gate field effect transistor on a semiconductor substrate, the insulated gate field effect transistor having an insulated gate electrode and source/drain regions of a first conductivity type; forming a first insulating film over the semiconductor substrate, the first insulating film covering the insulated gate electrode; forming a contact window through the first insulating film to at least one of the source/drain regions; embedding a metal plug in the contact window; forming a second insulating film having an oxygen blocking function on the first insulating film, the second insulating film covering the metal plug; forming a capacitor lower electrode on the second insulating film; forming a dielectric oxide film having a perovskite crystal structure on the lower electrode; annealing the semiconductor substrate in an oxygen-containing atmosphere after the step of forming the dielectric oxide film; and forming a capacitor upper electrode on the dielectric oxide film.
Using the metal plug facilitates to form a highly integrated semiconductor element. The second insulating film having an oxygen blocking function can prevent oxidation of the metal plug and can stably form a dielectric oxide film of a perovskite crystal structure.
As above, it is possible to use a metal plug and form a capacitor with a dielectric oxide film of a perovskite crystal structure having a high dielectric constant.
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Inoue Ken-ichi
Miyazawa Hisashi
Yamazaki Tatsuya
Armstrong,Westerman, Hattori, McLeland & Naughton, LLP
Fujitsu Limited
Loke Steven
Owens Douglas W.
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