Workpiece processing chamber having a thermal controlled microwave window
A plasma reactor has a microwave source including a microwave window with a channel extending through the window and a coolant source for flowing a coolant through the channel. The coolant is a liquid that does not absorb microwave power.
1. A plasma reactor for processing a workpiece, comprising:
a chamber and a workpiece support in said chamber, said chamber comprising a ceiling and a side wall, said ceiling comprising a microwave transmissive window having a disk shape;
a first gas distribution plate overlying said workpiece support and comprising plural gas injection orifices, a process gas plenum overlying said first gas distribution plate and a process gas supply conduit coupled to said process gas plenum;
a microwave radiator overlying said microwave transmissive window and comprising a cylindrical hollow conductive housing having a top, a side wall and a bottom floor, an array of openings in said bottom floor, and a microwave input port;
a coolant distribution path extending along a radial plane through said microwave transmissive window, said coolant distribution path comprising a central channel, an arcuate inlet plenum disposed around a first side of the central channel, an arcuate outlet plenum disposed around an opposite second side of the central channel and spaced apart from the arcuate inlet plenum by a separating wall there-between, an arcuate array of radial inlets connecting said arcuate inlet plenum to said central channel, an arcuate array of radial outlets connecting said central channel to said outlet plenum, an inlet port to the inlet plenum, and an outlet port from the outlet plenum, the outlet port positioned opposite the inlet port across the central channel; and
a coolant circulator coupled between said inlet port and said outlet port.
2. The plasma reactor of claim 1 further comprising a microwave generator coupled to said microwave input port and having an output power level of 800 kW in continuous wave mode or 1 megaWatt in pulsed mode.
3. The plasma reactor of claim 1 wherein said microwave transmissive window comprises a pair of parallel plates and said coolant distribution path comprises a space between said pair of parallel plates.
4. The plasma reactor of claim 1 further comprising:
a second gas distribution plate underlying said first gas distribution plate and comprising second plural gas injection orifices, an underlying process gas plenum between said first and second gas distribution plates, and a second process gas supply conduit coupled to said underlying process gas plenum.
5. The plasma reactor of claim 1 further comprising a coolant medium supply coupled to an interior of said microwave radiator.
6. The plasma reactor of claim 5 wherein said coolant medium supply is coupled to said microwave input port of said microwave radiator.
7. The plasma reactor of claim 1 further comprising:
a rotary waveguide coupling comprising:
(A) a stationary member fixed with respect to said chamber and comprising a microwave power receiving port, and
(B) a rotatable member coupled to said microwave input port of said microwave radiator and having an axis of rotation coincident with an axis of symmetry of said cylindrical hollow conductive housing; and,
a rotation actuator coupled to said rotatable member, whereby said microwave radiator is rotatable by said rotation actuator about said axis of symmetry.
8. The plasma reactor of claim 7 wherein:
said rotation actuator comprises a motor and a rotatable drive gear coupled to said motor;
said rotatable member comprises a driven gear fastened to said rotatable member and engaged with said rotatable drive gear.
9. The plasma reactor of claim 8 wherein said rotatable drive gear is at a stationary location and is rotatable about a radial axis, and said driven gear is at a location fixed relative to said rotatable member.
10. The plasma reactor of claim 7 further comprising an axial waveguide connected between said microwave input port of said microwave radiator and said rotatable member.
11. The plasma reactor of claim 10 wherein said axial waveguide is coaxial with said axis of symmetry.
12. The plasma reactor of claim 7 further comprising a microwave generator and a flexible waveguide conduit connected between said microwave generator and said microwave power receiving port of said stationary member.
13. The plasma reactor of claim 7 wherein said microwave radiator is capable of radiating at frequency not less than 2.45 GHz.
14. The plasma reactor of claim 7 wherein said array of openings in said bottom floor of said microwave radiator has a periodic spacing corresponding to a predetermined fraction of a microwave wavelength.
15. The plasma reactor of claim 14 wherein said microwave radiator has a radiation pattern with a periodic non-uniformity corresponding to said spacing, which is averaged out by rotation of said microwave radiator.
16. The plasma reactor of claim 1 further comprising:
an annular pocket formed in said microwave transmissive window;
an inductive coil antenna in said annular pocket;
a source of RF power coupled to said inductive coil antenna; and
a controller coupled to said source of RF power.
17. The plasma reactor of claim 1 wherein said inlet plenum and said outlet plenum each provide half of a circular annulus around the central channel.
18. The plasma reactor of claim 17 wherein the central channel is circular.
19. The plasma reactor of claim 1 wherein said microwave transmissive window comprises a dielectric material and said coolant distribution path comprises a passage in said dielectric material.