Capacitively coupled radiofrequency plasma source

Claim 2

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: a first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; a second electrode having a surface area facing toward said region and of a size significantly smaller than said predetermined size; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby with the strength of said magnetic field increasing in each direction of said field laterally away from said second electrode; and a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region.

Claim 3

A plasma source as defined in claim 1 in which said magnetic field curves over said surface of said second electrode and in which said surface area of said second electrode has a curvature substantially the same as that of said field.

Claim 4

A plasma source as defined in claim 1 in which said first electrode has the shape of a cylinder closed at one end and open at its other end through which charged particles are extracted from said plasma.

Claim 5

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: a first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; a second electrode having a surface area facing toward said region and of a size significantly smaller than said predetermined size, said second electrode being in the shape of an annular ring and said first electrode including a cylindrical wall axially surrounding said second electrode; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby with the strength of said magnetic field laterally increasing in each direction of said field away from said second electrode; and a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region.

Claim 6

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: a first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; a second electrode having a surface area facing toward said region and of a size significantly smaller than said predetermined size, said second electrode being in the shape of an annular ring and said first electrode including a cylindrical wall axially surrounding said second electrode; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby with the strength of said magnetic field laterally increasing in each direction of said field away from said second electrode; and a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region.

Claim 7

A plasma source as defined in claim 4 in which said second electrode is spaced inside said first electrode by a distance insufficient to enable entry of said plasma therebetween.

Claim 8

A plasma source as defined in claim 4 in which said field producer includes a plurality of permanent magnets individually spaced in succession circumferentially around said first electrode.

Claim 9

A plasma source as defined in claim 6 in which said first electrode has an end wall enclosing one end of said cylindrical wall and in which said field producer also includes a plurality of permanent magnets individually spaced in radial succession circumferentially over said end wall.

Claim 10

A plasma source as defined in claim 4 in which the strength of said magnetic field and the energy and mean path length for electrons in said plasma establish a plasma conductivity parallel to said magnetic field that is substantially greater than the plasma conductivity in a direction transverse to said magnetic field.

Claim 11

A plasma source as defined in claim 4 in which the strength of said magnetic field increases in the direction from said discharge region to said second electrode.

Claim 12

A plasma source as defined in claim 4 which further includes an accelerator for effecting the extraction of charged particles from said plasma.

Claim 13

A plasma source as defined in claim 10 in which said particles are extracted by said accelerator to move along a path in a given direction from said region and in which said second electrode is located laterally to one side of said path.

Claim 14

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: an essentially non-emissive first electrode spaced from a plasma discharge region within said source; an essentially non-emissive second electrode having a surface area facing said region; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region; and a field producer which develops a static unidirectional magnetic field oriented in a direction substantially parallel to said surface area as seen thereby in enhancement of the transfer of said energy to said plasma, the contact area between said second electrode and said plasma discharge region as oriented being sufficient to minimize sheath voltage at the boundry of said plasma.

Claim 15

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: an essentially non-emissive first electrode spaced from a plasma discharge region within said source; an essentially non-emissive second electrode having a surface area facing said region; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region; and a field producer which develops a static unidirectional magnetic field oriented in a direction substantially parallel to said surface area as seen thereby in enhancement of the transfer of said energy to said plasma, the contact area between said second electrode and said plasma discharge region as oriented being sufficient to minimize sheath voltage at the boundry of said plasma.

Claim 16

A plasma source as defined in claim 12 in which said field exhibits a variation in strength with respect to said second electrode in a direction which contains energetic electrons.

Claim 17

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: first electrode having a surface area facing a plasma discharge region within said source; an essentially non-emissive second electrode also having a surface area facing toward said region; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region, the contact area between said electrodes and said plasma discharge region as oriented being sufficient to minimize sheath voltage at the boundry of said plasma; and an apertured electrode for the efflux of charged particles from said plasma.

Claim 18

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: first electrode having a surface area facing a plasma discharge region within said source; an essentially non-emissive second electrode also having a surface area facing toward said region; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region, the contact area between said electrodes and said plasma discharge region as oriented being sufficient to minimize sheath voltage at the boundry of said plasma; and an apertured electrode for the efflux of charged particles from said plasma.

Claim 19

A plasma source as defined in claim 14 in which said apertured electrode is biased to extract one of electrons and ions from said plasma.

Claim 20

A plasma source as defined in claim 14 in which said field is configured with respect to said electrodes so as to contain energetic electrons.

Claim 21

A plasma source as defined in claim 14 in which the strength of said magnetic field and the energy and mean path length for electrons in said plasma establish a plasma conductiveity parallel to said magnetic field that is substantially greater than the plasma conductivity in a direction transverse to said magnetic field.

Claim 22

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: an essentially non-emissive first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; an essentially non-emissive second electrode also having a surface area facing toward said region and of a size significantly smaller than the predetermined size; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region, the contact area between said second electrode and said plasma discharge region as oriented being sufficient to minimize sheath voltage at the boundry of said plasma; and an apertured electrode for the efflux of charged particles from said plasma.

Claim 23

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: an essentially non-emissive first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; an essentially non-emissive second electrode also having a surface area facing toward said region and of a size significantly smaller than the predetermined size; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region, the contact area between said second electrode and said plasma discharge region as oriented being sufficient to minimize sheath voltage at the boundry of said plasma; and an apertured electrode for the efflux of charged particles from said plasma.

Claim 24

A plasma source as defined in claim 18 in which said apertured electrode is biased to extract one of electrons and ions from said plasma.

Claim 25

A plasma source as defined in claim 19 in which said field producer includes a plurality of permanent magnets individually spaced in succession circumferentially around a cylindrical wall of said first electrode.

Claim 26

A plasma source as defined in claim 20 in which said first electrode has an end wall enclosing one end of said cylindrical wall and in which said field producer also includes a plurality of permanent magnets individually spaced in radial succession circumferentially over said end wall.

Claim 27

A plasma source as defined in claim 19 in which said particles are extracted by said biased electrode to move along a path in a given direction from said region and in which said second electrode is aligned laterally and to one side of said path.

Claim 28

A plasma source as defined in claim 18 in which the strength of said magnetic field increases in each direction of said field away from said electrodes.

Claim 29

A plasma source as defined in claim 18 in which said magnetic field curves over said surface of said second electrode and in which said surface area of said second electrode has a curvature substantially the same as that of said field.

Claim 30

A plasma source as defined in claim 18 in which said first electrode has the shape of a cylinder closed at one end and open at its other end through which charged particles are extracted from said plasma.

Claim 31

A plasma source as defined in claim 18 in which said second electrode is in the shape of an annular ring and said first electrode includes a cylindrical wall axially surrounding said second electrode and in which said second electrode is spaced inside said first electrode by a distance insufficient to enable entry of said plasma therebetween.

Claim 32

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: an essentially non-emissive first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; an essentially non-emissive second electrode also having a surface area facing toward said region and of a size significantly smaller than the predetermined size; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region the strength of said magnetic field and the energy and mean path length for electrons in said plasma establishing a plasma conductivity parallel to said magnetic field that is substantially greater than the plasma conductivity in a direction transverse to said magnetic field; and an apertured electrode for the efflux of charged particles from said plasma.

Claim 33

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: an essentially non-emissive first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; an essentially non-emissive second electrode also having a surface area facing toward said region and of a size significantly smaller than the predetermined size; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region the strength of said magnetic field and the energy and mean path length for electrons in said plasma establishing a plasma conductivity parallel to said magnetic field that is substantially greater than the plasma conductivity in a direction transverse to said magnetic field; and an apertured electrode for the efflux of charged particles from said plasma.

Claim 34

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: a first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; a second electrode also having a surface area facing toward said region and of a size significantly smaller than the predetermined size; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby, the strength of said magnetic field increasing in the direction from said discharge region said second electrode; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region; and an apertured electrode for the efflux of charged particles from said plasma.

Claim 35

A plasma source operative within an evacuated environment into which an ionizable gas is introduced, comprising: a first electrode having a surface area of predetermined size facing generally toward a plasma discharge region within said source; a second electrode also having a surface area facing toward said region and of a size significantly smaller than the predetermined size; a field producer which develops a static unidirectional magnetic field oriented in a direction generally parallel to said surface area of said second electrode as seen thereby, the strength of said magnetic field increasing in the direction from said discharge region said second electrode; a source of radiofrequency energy coupled between said first and second electrodes to deliver energy in creation of a plasma discharge process within said region; and an apertured electrode for the efflux of charged particles from said plasma.