Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
1999-01-05
2001-10-16
Quach, T. N. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S300000, C257S751000, C257S764000
Reexamination Certificate
active
06303952
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates, in general, to an electrode contact structure containing a silicidation barrier that prevents silicidation of the structure electrode. More specifically, this invention relates to a ferroelectric capacitor electrode contact structure containing an oxide silicidation barrier that prevents silicidation of the structure electrode.
BACKGROUND OF THE INVENTION
Without limiting the scope of the invention, its background is described in connection with use of an oxide silicidation barrier in a ferroelectric capacitor. The ferroelectric dielectrics of such capacitors include lead zirconium titanate (PZT) and barium strontium titanate.
The development of ferroelectric memories has run into some serious problems. One main problem involves the fabrication of the contact between a polysilicon plug and the bottom electrode of a ferroelectric capacitor. Metal electrodes such as Ir, Pt, and Ru are generally applied to such ferroelectric capacitors.
SUMMARY OF THE INVENTION
The simplest structure for an electrode contact would be the placement of a metal electrode, such as Ir and Pt, directly on the polysilicon plug. However, such a structure cannot be used because a silicidation reaction takes place between the bottom electrode and the polysilicon plug when crystalline ferroelectric film ig formed at a temperature greater than 600° C.
Recently, titanium nitride, tantalum nitride, tantalum silicon nitride, and aluminum titanium nitride have been placed between the bottom electrodes and the polysilicon plug. However, such nitride films can be oxidized by oxygen which penetrates through the grain boundary of metal electrodes at high temperatures. Thus, no successful electrode structures have been developed to date.
The present invention involves the placement of a very thin multi-component oxide layer between the ferroelectric dielectric bottom electrode and the silicon-containing plug.
One use of this invention can be to isolate the bottom electrode and the silicon-containing plug by placing a barrier capable of suppressing the silicidation reaction between them while allowing the formation of an ohmic contact by increasing the defect density of natural silicon oxide film by doping with titanium oxide. Surprisingly, this multi-component oxide layer does not prevent the formation of an ohmic contact, even though the oxides are insulators. Also, surprisingly, this oxide layer substantially suppresses the silicidation reaction even though it is very thin.
The ferroelectric capacitor bottom electrode contact structure of the invention can comprise a semiconducting substrate, a via-containing insulator over the semiconducting substrate, a silicon-containing plug in the via-containing insulator, a multi-component oxide layer over the silicon-containing plug, and an electrode over the multi-component oxide layer, wherein a conductive path is routed from the silicon-containing plug to the electrode through the multi-component oxide layer.
The process for fabricating a ferroelectric capacitor bottom electrode contact structure of the invention can comprise the steps of forming at least one silicidation barrier source component on a silicon-containing plug, depositing a bottom electrode over the silicidation barrier source component, and annealing the contact structure.
REFERENCES:
patent: 5679980 (1997-10-01), Summerfelt
patent: 5744832 (1998-04-01), Wolters et al.
patent: 5773314 (1998-06-01), Jiang et al.
patent: 5777356 (1998-07-01), Dhote et al.
patent: 5892254 (1999-04-01), Park et al.
Ghandhi, S., VLSI Fabrication Principles, John Wiley & Sons, 1983, pp. 437-438.
Aoki Katsuhiro
Fukuda Yukio
Sakoda Tomoyuki
Brady III W. James
Garner Jacqueline J.
Quach T. N.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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