Capacitor and method of forming a capacitor

Details Capacitor and method of forming a capacitor Capacitor and method of forming a capacitor

1998-11-24

2001-10-09

Bowers, Charles (Department: 2813)

Semiconductor device manufacturing: process

Making field effect device having pair of active regions...

Having insulated gate

C438S253000, C438S762000, C438S791000

Reexamination Certificate

active

06300187

ABSTRACT:

BACKGROUND OF THE INVENTION
Capacitors are typically comprised of a pair of opposing conductive electrodes which are separated by one or more dielectric materials. A continuing goal in semiconductor circuitry fabrication is to shrink individual devices to increase circuit density and thereby the amount of circuitry which can be fit into a given space. Such can be achieved by both reducing the area over the substrate consumed by an individual device as well as in reducing its thickness.
One factor affecting a capacitor's construction and operation is breakdown voltage. Breakdown voltage is that voltage which causes the capacitor to form a conductive short between the electrodes through the dielectric material, thereby destroying the capacitor. It is function of the composition of the dielectric material as well as it thickness, among other factors. Generally if the inherent breakdown voltage of a given material can be increased, thickness of a capacitor dielectric layer for a given application could be reduced.
Silicon dioxide, silicon nitride and silicon oxynitride continue to find use as capacitor dielectric materials. One common composite of these materials utilized in capacitors as the dielectric layer is an oxide-nitride-oxide material commonly referred to as ONO. The first formed oxide layer comprises silicon dioxide typically formed by native oxidation of an oxidizable first or lower capacitor electrode comprising, for example, conductively doped polysilicon. Such typically produces a silicon dioxide layer approximately 20 Angstroms thick. Subsequently, a silicon nitride layer is deposited, such as by combining dichlorosilane and ammonia in a low pressure chemical vapor deposition reactor at 650° C. Such layer as deposited may not be as dense as desired. Accordingly, the silicon nitride layer is subjected to an oxidation step to densify and fill any pinholes inherent in the deposition which produces such layer. An example oxidation step flows equal amounts is of H
2
and O
2
at atmospheric pressure and 800° C. This transforms the outer 20 Angstroms or so of the silicon nitride layer into a silicon oxynitride material, typically designated as SiO
x
N
y
. This layer is what typically constitutes the outer “O” of the ONO capacitor dielectric layer or material.
Accordingly, it would be desirable to develop techniques and materials which inherently result in increased breakdown voltage of ONO capacitors, and silicon oxynitride capacitor dielectric layers particularly.
SUMMARY OF THE INVENTION
The invention comprises capacitors and methods of forming capacitors. In one implementation, a method of forming a capacitor includes forming a first capacitor electrode. An Si
3
N
4
comprising capacitor dielectric layer is formed over the first capacitor electrode. The Si
3
N
4
comprising layer is oxidized in the presence of a chlorine containing atmosphere under conditions which form a silicon oxynitride layer comprising chlorine atop the Si
3
N
4
layer. In one aspect, the oxidizing sequentially comprises a dry oxidation in the presence of an oxygen containing gas in the substantial absence of chlorine, a dry oxidation in the presence of a gas comprising oxygen and chlorine, and a wet oxidation comprising chlorine. A second capacitor electrode is formed over the chlorine containing silicon oxynitride layer.
In one implementation, a method of forming a capacitor comprises forming a first capacitor electrode. A capacitor dielectric layer comprising a silicon oxynitride region is formed over the first capacitor electrode. The silicon oxynitride region is exposed to a chlorine containing atmosphere under conditions effective to incorporate chlorine within the silicon oxynitride region. A second capacitor electrode is formed over the chlorine containing silicon oxynitride layer.
In one implementation, a capacitor comprises a first capacitor electrode, a second capacitor electrode, and a capacitor dielectric material received intermediate the first and second capacitor electrodes.
At least a portion of the capacitor dielectric material comprises chlorine atoms present at a concentration of at least about 5×10
20
atoms/cm
3


REFERENCES:
patent: 5712208 (1998-01-01), Tseng et al.
patent: 5861190 (1999-01-01), Greene et al.
patent: 6163050 (2000-12-01), Hisatomi et al.
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patent: 3-203329 (1991-09-01), None
patent: 3203329 (1991-11-01), None
patent: 5206412 (1993-08-01), None
patent: 408330738A (1996-12-01), None

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