Plasma reactor

Details Plasma reactor Plasma reactor

1991-01-07

1991-11-05

LaRoche, Eugene R.

Electric lamp and discharge devices: systems

Discharge device load with fluent material supply to the...

Plasma generating

31323131, H05H 124

Patent

active

050633309

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to plasma reactors. It finds an application in the surface treatment of samples, in particular, in micro-electronics.
Plasma reactors are already known that comprise a housing placed in a vacuum capable of receiving a selected gas flow, a microwave generator and wave guide means for passing the microwaves to the housing.
To render the plasma homogeneous with a view to obtaining a better surface treatment of samples for example, provision is most frequently made for applying a magnetic diffusion field in the housing.
Now the application of such a magnetic diffusion field has the drawback that it consumes a large amount of energy, sometimes exceeding that used to produce the plasma.
The result is a limitation of the reactor dimensions and therefore of the dimensions of the plasma obtained, which prevents the treatment of samples with large diameters.


SUMMARY OF THE INVENTION

The object of the invention is to provide a solution of this problem.
More particularly, it aims to improve the flexibility of use of the plasma reactor and its versatility in application.
The invention relates to a plasma reactor comprising: a housing capable of receiving a selected gaseous flow, a microwave generator and wave guide means for passing the microwave to the housing along a non-resonant coupling wherein the housing does not dissipate, in the form of electromagnetic radiation, the ultrahigh frequency energy imparted thereto in the presence of gas.
According to a general definition of the invention, since the housing is of a large size, the end portion of the wave guide means is progressively reduced in one direction and widened in the other, until it reaches a flat rectangular cross section completely surrounding the said housing and produces a non-resonant coupling therewith.
According to one aspect of the invention, provision is made for a piston type ultrahigh frequency short circuit means, completely surrounded by the end portion of the wave guide means and disposed on the diametrically opposite side relative to the microwave intake, the said piston being adjusted so as to define a desired ultrahigh frequency electric field in the housing.
In the field of industrial applications of the plasma reactor in accordance with the invention, the ultrahigh frequency short circuit means is advantageously immovable.
In the field of experimental applications of the plasma reactor in accordance with the invention, the ultrahigh frequency short circuit means is preferably movable.
According to a preferred mode of embodiment of the invention, the housing comprises an internal tubular element placed in a vacuum and being concentric with the housing, the wall of the said tubular element being constituted by a material having low dielectric losses, such as quartz.
According to another characteristic of the invention, provision is made inside the housing for an additional ultrahigh frequency short circuit means coupled with the tubular element and having a first and second annular disc surrounding the said tubular element, the annular discs being separated from each other by a predetermined and adjustable distance with a view to confining the plasma in the portion of the tubular element comprised between the said annular discs.
In the field of industrial applications of the plasma reactor in accordance with the invention, the additional ultrahigh frequency short circuit means is immovable.
In the field of experimental applications of the plasma reactor in accordance with the invention, the additional ultrahigh frequency short circuit means is movable.
According to another aspect of the invention, the wave guide comprises in its intermediate portion, adjustment means such as a plurality of adjustable penetrating screws.
As a variant, the wave guide comprises in its intermediate end portion tapering in one direction and widened in the other, adjustment means such a plurality of adjustable penetrating screws.
In the sphere of a plasma reactor intended for the surface treatment of a sample,

REFERENCES:
patent: 3814983 (1974-06-01), Weissfloch et al.
patent: 4859909 (1989-08-01), Gualandris et al.
patent: 4866346 (1989-09-01), Giaudreau et al.
patent: 4970435 (1990-11-01), Tanaka et al.
patent: 4987346 (1991-01-01), Katzschner et al.
patent: 5003225 (1991-03-01), Daudl

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