Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Magnet structure or material
Reexamination Certificate
2003-06-02
2004-07-20
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Magnet structure or material
C335S297000, C335S298000, C335S306000, C204S298160, C204S298190
Reexamination Certificate
active
06765466
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a magnetic field generator, and more specifically to such a generator for effectively confining magnetron plasma which is produced within a vacuum chamber in which a workpiece is positioned so as to be subject to plasma treatment.
2. Description of Related Art
It is known in the art to generate magnetron plasma, within an evacuated process chamber (viz., vacuum chamber), for use in implementing plasma treatment such as etching, film growth, etc. on the workpiece such as a semiconductor wafer provided in the chamber.
Prior to turning to the present invention, it is deemed advantageous to briefly describe, with reference to
FIG. 1
, a conventional magnetic field generator via which the plasma produced within the vacuum chamber is confined, When performing the plasma treatment (processing) on the workpiece, it is vital to effectively confine plasma in a manner to surround the workpiece so as to obtain designed results.
As shown in
FIG. 1
, a semiconductor wafer (viz., workpiece)
10
is positioned at the center area of a vacuum chamber
12
in a manner to face the surface of the workpiece upward on which the plasma treatment is to be carried out. Although not shown in
FIG. 1
, plasma is generated within the vacuum chamber
12
by way of conventional technology. The plasma generation per se is not directly concerned with the present invention, and thus the further description thereof will be omitted for the sake of simplifying the instant disclosure.
In order to effectively confine plasma around the workpiece
10
with forming no magnetic field above the wafer
10
(or with permitting very week magnetic field above the wafer), a magnetic field generator (or multi-pole magnet unit)
14
is provided outside the vacuum chamber
12
. The magnetic field generator
14
is comprised of a ring-like magnetic member (supporter)
16
and a plurality of segment type permanent magnets (hereinafter referred to as segment magnets)
18
attached to the inner side of the member
16
. More specifically, the segment magnets
18
are arranged such as to alternately change the magnetic polarities thereof in the circumferential direction of the supporter
16
, and thus, a multi-pole magnetic field is generated within the vacuum chamber
12
so as to confine the plasma around the workpiece
10
. Small arrows on the segment magnets
18
respectively indicate the magnetized directions of the magnets
18
, and curved lines
20
respectively indicate magnetic forth lines.
It is typical in the art, when constructing the magnetic field generator
14
, to make use of the permanent magnets
18
rather than electromagnets because the electric power consumption can be zeroed and the structure of the apparatus can be simplified. On the other hand, a study made by the inventor of the instant application has revealed that the plasma treatment rate (i.e., etch rate) on the wafer surface depends on the strength of the multi-pole magnetic field. However, there has been no proposal to control the multi-pole magnetic field which is generated using a multiple of permanent magnets. In other words, a permanent magnet type conventional magnetic field generator is unable to adaptively control the magnetic field strength.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a magnetic field generator wherein the strength of the multi-pole magnetic field generated thereby can adaptively be controlled.
One aspect of the present invention resides in a magnetic field generator for generating a multi-pole magnetic field around a workpiece positioned within a vacuum chamber. The magnetic field generator is provided outside the vacuum chamber and comprises a plurality of segment type permanent magnets circularly arranged. The magnetic field generator further comprises a plurality of magnetic members to which the segment magnets are selectively attached.
REFERENCES:
patent: 5262028 (1993-11-01), Manley
patent: 5746897 (1998-05-01), Heimanson et al.
Barrera Ramon M.
Shin-Etsu Chemical Co. , Ltd.
LandOfFree
Magnetic field generator for magnetron plasma does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic field generator for magnetron plasma, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic field generator for magnetron plasma will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3197597