Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1998-06-12
2001-04-17
Everhart, Caridad (Department: 2825)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S785000, C438S790000, C427S126300
Reexamination Certificate
active
06218300
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of dielectric layer formation and more specifically to a method and apparatus for forming a titanium doped tantalum pentaoxide dielectric layer.
2. Discussion of Related Art
Integrated circuits are made up of literally millions of active and passive devices such as transistors, capacitors and resistors. In order to provide more computational power and/or more storage capability in an integrated circuit, device features are reduced or scaled down in order to provide higher packing density of devices. An important feature to enable scaling of devices is the ability to form high quality, high dielectric constant films for capacitor and gate dielectrics.
One high dielectric constant film that has been proposed is titanium doped tantalum pentaoxide. A conventional method of forming a titanium doped tantalum pentaoxide film is to first deposit a tantalum pentaoxide (Ta
2
O
5
) film and then use ion implantation to dope the film with titanium atoms. A problem with doping the film with ion implantation is that the doping profile for flat surfaces (horizontal surfaces) will differ from that on side surfaces (vertical surfaces). Such differences in doping can cause the different areas to have different electrical properties which makes the process unacceptable in the manufacture of high density capacitors which utilize electrode designs with large aspect ratio openings (greater than 2:1). Additionally, ion implanting titanium atoms into a tantalum pentaoxide film can cause lattice destruction resulting in poor electrical performance such as high leakage currents.
Thus, what is desired is a method and apparatus for forming a titanium doped tantalum pentaoxide film.
SUMMARY OF THE INVENTION
A method and apparatus for forming a titanium doped tantalum pentaoxide dielectric using a chemical vapor deposition (CVD) process is described. According to the present invention a substrate is placed in the deposition chamber. A source of tantalum, a source of titanium, and a source of oxygen are then fed into the chamber. Thermal energy is used to decompose the source of tantalum to form tantalum atoms, and decompose the source of titanium to form titanium atoms in the deposition chamber. The titanium atoms, tantalum atoms and source of oxygen react to form a tantalum pentaoxide dielectric film doped with titanium.
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Treichel, et al. Deposition, annealing and characterization of high-dielectric constant metal oxide films;, Adv. Mat. for Optics and Electronics, vol. 5, No. 3, pp163-175, May 1995.*
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“Deposition, Annealing and Characterisation of High-dielectric-constant Metal Oxide Films” Avanced Materials for Optics and Electronics vol. 5, No. 3 May 1995 pp. 163-175, H. Treichel, et al.
“Insulation Layer of Capacitor Having High Dielectric Constant . . . ” Baek, et al. Feb. 2, 1995, KR 9500 861 Abstract.
Chemical Vapor Deposition of Doped TiO2 Thin Films Sarah R. Kurtz and Roy G. Gordon Thin Solid Films, vol. 147, No. 2 Jan. 1, 1987 pp. 167-176.
Liu Patricia
Narwankar Pravin K.
Sahin Turgut
Urdahl Randall S.
Velaga Ankineedu
Applied Materials Inc.
Blakely & Sokoloff, Taylor & Zafman
Everhart Caridad
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