Semiconductor device manufacturing: process – Having magnetic or ferroelectric component
Reexamination Certificate
2000-01-04
2001-07-10
Everhart, Caridad (Department: 2825)
Semiconductor device manufacturing: process
Having magnetic or ferroelectric component
C438S396000, C438S691000
Reexamination Certificate
active
06258608
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for fabricating a ferroelectric capacitor, and more particularly to a method for removing a non-perovskite crystalline phase including pryochlore after forming a crystalline perovskite ferroelectric material in a ferroelectric capacitor process.
BACKGROUND OF THE INVENTION
Modern data processing systems require that a substantial portion of the information stored in its memory be randomly accessible to ensure rapid access to such information. Such randomly accessible devices include ferroelectric random access memories (FRAMs). FRAMs exhibit significant advantage of being nonvolatile which is achieved by virtue of the fact that a ferroelectric capacitor includes a pair of capacitor plates with a ferroelectric material between them which has two different stable polarization states which can be defined with a hysteresis loop depicted by plotting the polarization against applied voltage.
A method for using a ferroelectric material between two electrodes is taught in U.S. Pat. No. 5,728,603 entitled “Method of forming a crystalline ferroelectric dielectric material for an integrated circuit” by Emesh et al., which is hereby incorporated herein by reference.
Though the above mentioned patent relates to perovskite formation by varying post-annealing condition, formation of nonpolar pyrochlore phase formation was obtained.
Since the pyrochlore can be formed in the formation of the ferroelectric dielectric film with crystalline perovskite structure by the process of depositing a layer of amorphous ferroelectric precursor material and then annealing, it is required to remove the nonpolar(non perovskite) phase including pyrochlore following the annealing process from a top surface of the ferroelectric dielectric film.
SUMMARY OF THE INVENTION
The present invention addresses the above problem with a method of forming a ferroelectric crystalline perovskite phase.
According to an aspect of the present invention, a method of forming a crystalline perovskite ferroelectric material comprises the steps of forming a lower capacitor electrode layer on an integrated circuit substrate; depositing an amorphous ferroelectric material layer on the lower capacitor electrode layer; annealing the amorphous ferroelectric material layer to cause a phase transformation to a ferroelectric crystalline perovskite phase, wherein the annealing forms a non-perovskite crystalline phase including pyrochlore on a surface of the ferroelectric material layer of crystalline perovskite phase; selectively removing the non-perovskite crystalline phase from the surface of the ferroelectric material layer.
According to another aspect of the present invention, a method of fabricating a ferroelectric capacitor comprises the steps of forming a lower capacitor electrode on an insulating layer that covers a semiconductor substrate; depositing an amorphous ferroelectric material layer on the lower capacitor electrode; annealing the amorphous ferroelectric material layer to cause a phase transformation to a ferroelectric crystalline perovskite phase, wherein the annealing forms a non-perovskite crystalline phase including pyrochlore on a top surface of the ferroelectric material layer of crystalline perovskite phase; selectively removing the non-perovskite crystalline phase from the surface of the ferroelectric material layer; and forming an upper capacitor electrode over the ferroelectric material layer.
According to yet another aspect of the present invention, a method of forming a crystalline perovskite ferroelectric material comprises the steps of depositing an amorphous ferroelectric material layer on an integrated circuit substrate; annealing the amorphous ferroelectric material layer to cause a phase transformation to a ferroelectric crystalline perovskite phase, wherein the annealing forms a non-perovskite crystalline phase including pyrochlore on a surface of the ferroelectric material layer of crystalline perovskite phase; and removing the non-perovskite crystalline phase by dry etching.
According to yet another aspect of the present invention, a method of forming a crystalline perovskite ferroelectric material comprises the steps of depositing an amorphous ferroelectric material layer on an integrated circuit substrate; annealing the amorphous ferroelectric material layer to cause a phase transformation to a ferroelectric crystalline perovskite phase, wherein the annealing forms a non-perovskite crystalline phase including pyrochlore on a surface of the ferroelectric material layer of crystalline perovskite phase; and removing the non-perovskite crystalline phase by sequentially performing dry etching and wet etching.
According to yet another aspect of the present invention, a method of fabricating a ferroelectric capacitor comprises the steps of forming a lower capacitor electrode on an insulating layer that covers a semiconductor substrate; depositing an amorphous ferroelectric material layer on the lower capacitor electrode; annealing the amorphous ferroelectric material layer to cause a phase transformation to a ferroelectric crystalline perovskite phase, wherein the annealing forms a non-perovskite crystalline phase including pyrochlore on a top surface of the ferroelectric material layer of crystalline perovskite phase; removing the non-perovskite crystalline phase by sequentially performing dry etching and wet etching; and forming an upper capacitor electrode over the ferroelectric material layer.
According to yet another aspect of the present invention, a method of fabricating a ferroelectric capacitor comprises the steps of forming a lower capacitor electrode on an insulating layer that covers a semiconductor substrate; depositing an amorphous ferroelectric material layer on the lower capacitor electrode; annealing the amorphous ferroelectric material layer so as to cause a phase transformation to a ferroelectric crystalline perovskite phase, wherein the annealing forms a non-perovskite crystalline phase including pyrochlore on a top surface of the ferroelectric material layer of crystalline perovskite phase; selectively removing the non-perovskite crystalline phase from the surface of the ferroelectric material layer; forming an upper capacitor electrode over the ferroelectric material layer; sequentially patterning the upper capacitor electrode, the ferroelectric material layer of crystalline perovskite phase and the lower capacitor electrode, thereby forming the ferroelectric capacitor.
Various other objects, features and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views.
REFERENCES:
patent: 5258093 (1993-11-01), Maniar
patent: 5728603 (1998-03-01), Emesh et al.
patent: 6051914 (2000-04-01), Nishiwaki
Everhart Caridad
Lee Calvin
Samsung Electronics Co,. Ltd.
The Law Offices of Eugene M. Lee, PLLC
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