Fast transition RF impedance matching network for plasma reactor ignition
First Claim
1. An impedance matching network for an RF plasma reactor having RF excitation apparatus receiving RF power through said impedance matching network from an RF generator to ignite and maintain a plasma in said reactor, and presenting a plasma impedance to said impedance matching network, said network comprising:
- a current path including an input conductor connectable to said RF generator and an output conductor connectable to said RF excitation apparatus;
a common return connection;
at least one vacuum variable capacitor connected between said current path and said common return connection and having a variable capacitance value corresponding to a match to said plasma impedance during a steady state of said plasma;
at least a first air variable capacitor connected in parallel with said at least one vacuum variable capacitor, said first air variable capacitor being switchable between a high capacitance value providing a match to said plasma impedance during an onset of plasma ignition, and a negligible capacitance value with respect to said high capacitance value; and
means coupled to said first air variable capacitor for setting said first air variable capacitor to said high capacitance value prior to ignition of said plasma in said reactor and for switching said first air variable capacitor from said high to said negligible capacitance value upon said plasma reaching said steady state.
0 Assignments
0 Petitions
Accused Products
Abstract
An impedance matching network for an RF coupled plasma reactor having RF excitation apparatus receiving RF power through the impedance matching network from an RF generator for producing a plasma in the reactor has at least one capacitor connected to the output of the RF generator and having a capacitance value providing an impedance match to the plasma impedance during a steady state of the plasma, at least a first rapidly tunable capacitor connected in parallel with the one capacitor, the rapidly tunable capacitor being rapidly switchable between a high capacitance value providing a match to the plasma impedance during the onset of plasma ignition and a lesser minimum capacitance value, and a controller for rapidly switching the rapidly tunable capacitor from the high to the lesser capacitance value upon reaching the plasma steady state.
109 Citations
29 Claims
-
1. An impedance matching network for an RF plasma reactor having RF excitation apparatus receiving RF power through said impedance matching network from an RF generator to ignite and maintain a plasma in said reactor, and presenting a plasma impedance to said impedance matching network, said network comprising:
-
a current path including an input conductor connectable to said RF generator and an output conductor connectable to said RF excitation apparatus; a common return connection; at least one vacuum variable capacitor connected between said current path and said common return connection and having a variable capacitance value corresponding to a match to said plasma impedance during a steady state of said plasma; at least a first air variable capacitor connected in parallel with said at least one vacuum variable capacitor, said first air variable capacitor being switchable between a high capacitance value providing a match to said plasma impedance during an onset of plasma ignition, and a negligible capacitance value with respect to said high capacitance value; and means coupled to said first air variable capacitor for setting said first air variable capacitor to said high capacitance value prior to ignition of said plasma in said reactor and for switching said first air variable capacitor from said high to said negligible capacitance value upon said plasma reaching said steady state. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An impedance matching network for an RF plasma reactor having RF excitation apparatus receiving RF power through said impedance matching network from an RF generator to ignite and maintain a plasma in said reactor, and presenting a plasma impedance to said impedance matching network, said network comprising:
-
an input conductor connectable to said RF generator; an output conductor connectable to said RF excitation apparatus; means coupled to said output conductor for sensing whenever said plasma reaches said steady state; a common return connection; at least one capacitor connected in series between said input and output conductors, and having a variable capacitance value corresponding to a match to said plasma impedance during a steady state of said plasma; at least a first tunable capacitor connected in parallel with said at least one capacitor, said first tunable capacitor being switchable between a high capacitance value providing a match to said plasma impedance during onset of plasma ignition and a negligible capacitance value with respect to said high capacitance value, within a fraction of a second over many repetitions; and means coupled to said first tunable capacitor for setting said first tunable capacitor to said high capacitance value prior to ignition of said plasma in said reactor and for switching said first tunable capacitor from said high to said negligible capacitance value upon said plasma reaching said steady state, said means for switching including actuator means linked to said first tunable capacitor for controlling said first tunable capacitor in response to said means for sensing, said first tunable capacitor tuned by movement of a mechanical link which is part of said actuator means.
-
-
7. An impedance matching network for an RF plasma reactor having RF excitation apparatus receiving RF power through said impedance matching network from an RF generator to ignite and maintain a plasma in said reactor, and presenting a plasma impedance to said impedance matching network, said network comprising:
-
a current path including an input conductor connectable to said RF generator and an output conductor connectable to said RF excitation apparatus; a common return connection; at least one capacitor connected between said current path and said common return connection and having a variable capacitance value corresponding to a match to said plasma impedance during a steady state of said plasma; means coupled to said output conductor for sensing whenever said plasma reaches said steady state; at least a first tunable capacitor connected in parallel with said at least one capacitor, said first tunable capacitor being switchable between a high capacitance value providing a match to said plasma impedance during onset of plasma ignition and a negligible capacitance value with respect to said high capacitance value, within a fraction of a second over many repetitions; and means coupled to said first tunable capacitor for setting said first tunable capacitor to said high capacitance value prior to ignition of said plasma in said reactor and for switching said first tunable capacitor from said high to said negligible capacitance value upon said plasma reaching said steady state, said means for switching including actuator means linked to said first tunable capacitor for controlling said first tunable capacitor in response to said means for sensing, said first tunable capacitor tuned by movement of a mechanical link which is part of said actuator means. - View Dependent Claims (8, 9, 10)
-
-
11. An impedance matching network for matching the RF impedance of an RF generator for igniting and maintaining a plasma within a plasma reactor with a plasma impedance of an RF input of the plasma reactor, comprising:
-
a current path including an input conductor connectable to said RF generator and an output conductor connectable to said RF input; a common return connection; at least one vacuum variable capacitor connected between said current path and said common return connection, said at least one vacuum variable capacitor being variable within a first capacitance range at a first tuning rate; and an air variable capacitor electrically disposed in parallel to said at least one vacuum variable capacitor and being varied upon an ignition of said plasma within said plasma reactor, said air variable capacitor being varied within a second capacitance range at a second tuning rate, said second tuning rate being substantially greater than said first tuning rate such that said impedance matching network is capable of maintaining impedance matching between onset of the ignition of said plasma and reaching of a steady state condition by said plasma. - View Dependent Claims (12, 13)
-
-
14. An impedance matching network for an RF plasma reactor having RF excitation apparatus receiving RF power through said impedance matching network from an RF generator to ignite and maintain a plasma in said reactor, and presenting a plasma impedance to said impedance matching network, said network comprising:
-
a current path including an input conductor connectable to said RF generator and an output conductor connectable to said RF excitation apparatus; a common return connection; at least one capacitor connected between said current path and said common return connection and having a variable capacitance value corresponding to a match to said plasma impedance during a steady state of said plasma; means coupled to said output conductor for sensing whenever said plasma reaches said steady state; at least a first tunable capacitor connected in parallel with said at least one capacitor, said first tunable capacitor being switchable between a high capacitance value providing a match to said plasma impedance during onset of plasma ignition, and a negligible capacitance value with respect to said high capacitance value; a source of compressed air; and means coupled to said first tunable capacitor for setting said first tunable capacitor to said high capacitance value prior to ignition of said plasma in said reactor and for switching said first tunable capacitor from said high to said negligible capacitance value upon said plasma reaching said steady state, wherein said means for switching includes actuator means linked to said first tunable capacitor for controlling said first tunable capacitor in response to said means for sensing, said actuator means comprising an air valve connected to said source of compressed air and governed by said means for sensing, a pneumatic rotor driven by compressed air from said air valve, and a mechanical link connected to said rotor so that said first tunable capacitor is tuned by movement of said mechanical link. - View Dependent Claims (15, 16, 17)
-
-
18. An impedance matching network for an RF plasma reactor having RF excitation apparatus receiving RF power through said impedance matching network from an RF generator to ignite and maintain a plasma in said reactor, and presenting a plasma impedance to said impedance matching network, said network comprising:
-
an input conductor connectable to said RF generator; an output conductor connectable to said RF excitation apparatus; a common return connection; at least one vacuum variable capacitor connected in series between said input and output conductors, and having a variable capacitance value corresponding to a match to said plasma impedance during a steady state of said plasma; at least a first air variable capacitor connected in parallel with said at least one vacuum variable capacitor, said first air variable capacitor being switchable between a high capacitance value providing a match to said plasma impedance during an onset of plasma ignition, and a negligible capacitance value with respect to said high capacitance value; and means coupled to said first air variable capacitor for setting said first air variable capacitor to said high capacitance value prior to ignition of said plasma in said reactor and for switching said first air variable capacitor from said high to said negligible capacitance value upon said plasma reaching said steady state. - View Dependent Claims (19, 20, 21, 22)
-
-
23. An impedance matching network for an RF plasma reactor having RF excitation apparatus receiving RF power through said impedance matching network from an RF generator to ignite and maintain a plasma in said reactor, and presenting a plasma impedance to said impedance matching network, said network comprising:
-
an input conductor connectable to said RF generator; an output conductor connectable to said RF excitation apparatus; a common return connection; at least one capacitor connected in series between said input and output conductors, and having a variable capacitance value corresponding to a match to said plasma impedance during a steady state of said plasma; means coupled to said output conductor for sensing whenever said plasma reaches said steady state; at least a first tunable capacitor connected in parallel with said at least one capacitor, said first tunable capacitor being switchable between a high capacitance value providing a match to said plasma impedance during onset of plasma ignition, and a negligible capacitance value with respect to said high capacitance value; a source of compressed air; and means coupled to said first tunable capacitor for setting said first tunable capacitor to said high capacitance value prior to ignition of said plasma in said reactor and for switching said first tunable capacitor from said high to said negligible capacitance value upon said plasma reaching said steady state, wherein said means for switching includes actuator means linked to said first tunable capacitor for controlling said first tunable capacitor in response to said means for sensing, said actuator means comprising an air valve connected to said source of compressed air and governed by said means for sensing, a pneumatic rotor driven by compressed air from said air valve, and a mechanical link connected to said rotor so that said first tunable capacitor is tuned by movement of said mechanical link. - View Dependent Claims (24, 25, 26)
-
-
27. An impedance matching network for matching the RF impedance of an RF generator for igniting and maintaining a plasma within a plasma reactor with a plasma impedance of an RF input of the plasma reactor, comprising:
-
an input conductor connectable to said RF generator; an output conductor connectable to said RF input; at least one vacuum variable capacitor connected in series between said input and output conductors, said at least one vacuum variable capacitor being variable within a first capacitance range at a first tuning rate; and an air variable capacitor electrically disposed in parallel to said at least one vacuum variable capacitor and being varied upon an ignition of said plasma within said plasma reactor, said air variable capacitor being variable within a second capacitance range at a second tuning rate, said second tuning rate being substantially greater than said first tuning rate such that said impedance matching network is capable of maintaining impedance matching between onset of the ignition of said plasma and reaching of a steady state condition by said plasma. - View Dependent Claims (28, 29)
-
Specification