Plasma reactor with overhead RF source power electrode having a resonance that is virtually pressure independent
First Claim
Patent Images
1. A plasma reactor, comprising:
- a chamber enclosure and a wafer support pedestal within said chamber enclosure;
an overhead electrode facing said wafer support pedestal and having a capacitance to ground;
an RF plasma source power generator and a fixed impedance match element coupled to said RF plasma source power generator and to said overhead electrode;
an RF plasma bias power generator and an impedance match circuit coupled to said RF plasma bias power generator;
said wafer support pedestal comprising;
(a) a conductive RF feed layer coupled to said impedance match circuit;
(b) a grounded base layer;
(c) a dielectric gap separating said grounded base layer from said conductive RF feed layer to form a capacitor across the dielectric gap, said capacitor having a capacitance to ground that is within an order of magnitude of the capacitance to ground of said overhead electrode.
1 Assignment
0 Petitions
Accused Products
Abstract
A plasma reactor operable over a very wide process window of pressure, source power and bias power includes a resonant circuit consisting of an overhead electrode having a first impedance, a wafer support pedestal having a second impedance and a bulk plasma having a third impedance and generally lying in a process zone between the overhead electrode and the wafer support pedestal, the magnitudes of the impedances of the overhead electrode and the wafer support pedestal being within an order of magnitude of one another, the resonant circuit having a resonant frequency determined by the first, second and third impedances.
-
Citations
22 Claims
-
1. A plasma reactor, comprising:
-
a chamber enclosure and a wafer support pedestal within said chamber enclosure;
an overhead electrode facing said wafer support pedestal and having a capacitance to ground;
an RF plasma source power generator and a fixed impedance match element coupled to said RF plasma source power generator and to said overhead electrode;
an RF plasma bias power generator and an impedance match circuit coupled to said RF plasma bias power generator;
said wafer support pedestal comprising;
(a) a conductive RF feed layer coupled to said impedance match circuit;
(b) a grounded base layer;
(c) a dielectric gap separating said grounded base layer from said conductive RF feed layer to form a capacitor across the dielectric gap, said capacitor having a capacitance to ground that is within an order of magnitude of the capacitance to ground of said overhead electrode. - View Dependent Claims (2)
-
-
3. A plasma reactor comprising:
-
a resonant circuit comprising an overhead electrode having a first impedance, a wafer support pedestal having a second impedance and a bulk plasma having a third impedance and generally lying in a process zone between said overhead electrode and said wafer support pedestal, the magnitudes of the impedances of said overhead electrode and said wafer support pedestal being within an order of magnitude of one another, said resonant circuit having a resonant frequency determined by said first, second and third impedances;
an RF plasma source power generator having a frequency at least nearly matching said resonant frequency; and
a fixed impedance match element coupled to said RF plasma source power generator and to said overhead electrode. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A plasma reactor comprising:
-
a resonant circuit comprising an overhead electrode having a first impedance, a wafer support pedestal having a second impedance and a bulk plasma having a third impedance and generally lying in a process zone between said overhead electrode and said wafer support pedestal, said resonant circuit having a resonant frequency determined by said first, second and third impedances;
an RF plasma source power generator having a frequency at least nearly matching said resonant frequency; and
a fixed impedance match element coupled to said RF plasma source power generator and to said overhead electrode, wherein the impedance of said bulk plasma changes with gas pressure inside said reactor, and wherein said impedance of said wafer support pedestal near said resonant frequency is sufficient to maintain a VSWR at said RF plasma source power generator not exceeding 3;
1 for fluctuations in said pressure from 10 mT to 900 mT.
-
-
17. A method of operating a plasma reactor, comprising:
-
providing a resonant circuit comprising an overhead electrode having a first impedance, a wafer support pedestal having a second impedance and a bulk plasma having a third impedance and generally lying in a process zone between said overhead electrode and said wafer support pedestal, said resonant circuit having a resonant frequency determined by said first, second and third impedances;
providing an RF plasma source power generator having a frequency at least nearly matching said resonant frequency; and
providing a fixed impedance match element coupled to said RF plasma source power generator and said overhead electrode. - View Dependent Claims (18)
-
-
19. In a plasma reactor having a generally cylindrical chamber, a method of radially confining a plasma within a process zone, said method comprising:
-
providing a resonant circuit comprising an overhead electrode having a first impedance, a wafer support pedestal having a second impedance and a bulk plasma having a third impedance and generally lying in a process zone between said overhead electrode and said wafer support pedestal, said resonant circuit having a resonant frequency determined by said first, second and third impedances;
coupling RF plasma source power at a frequency at least nearly matching said resonant frequency to the overhead electrode through a fixed impedance match element;
coupling RF plasma bias power through an impedance match circuit to the wafer support pedestal;
providing a path to ground in the fixed impedance match element having a sufficiently low impedance at the frequency of said RF plasma bias power to render the overhead electrode a low impedance path to ground for the RF plasma bias power; and
providing a uniform impedance across a surface of the wafer support pedestal at the frequencies of both the RF plasma source power and the RF plasma bias power simultaneously, said uniform impedance being sufficiently low at the frequency of the RF plasma source power to render the wafer support pedestal the lowest impedance path to ground for the RF plasma source power. - View Dependent Claims (20, 21, 22)
-
Specification