Externally excited torroidal plasma source with magnetic control of ion distribution

A plasma reactor for processing a workpiece, said plasma reactor comprising:

• an enclosure;
• a workpiece support within the enclosure facing an overlying portion of the enclosure, said workpiece support and the overlying portion of said enclosure defining a process region therebetween extending generally across the diameter of said wafer support;
• said enclosure having at least first and second openings therethrough near generally opposite sides of said workpiece support;
• at least one hollow conduit outside of said process region and connected to said first and second openings, providing a first torroidal path extending through said conduit and across said process region;
• a first RF power applicator coupled to the interior of said hollow conduit and capable of maintaining a plasma in said torroidal path;
• and
• a magnet for controlling radial distribution of plasma ion density in said processing region, said magnet comprising an elongate pole piece defining a pole piece axis intersecting said processing region.

A plasma reactor for processing a workpiece, said plasma reactor comprising:

• an enclosure;
• a workpiece support within the enclosure facing an overlying portion of the enclosure, said workpiece support and the overlying portion of said enclosure defining a process region therebetween extending generally across the diameter of said wafer support;
• said enclosure having at least first and second openings therethrough near generally opposite sides of said workpiece support;
• at least one hollow conduit outside of said process region and connected to said first and second openings, providing a first torroidal path extending through said conduit and across said process region;
• a first RF power applicator coupled to the interior of said one hollow conduit and capable of maintaining a plasma in said first torroidal path;
• at least third and fourth openings therethrough near generally opposite sides of said workpiece support and disposed along an axis transverse to an axis of said first and second openings;
• a second hollow conduit generally transverse to said one hollow conduit and disposed outside of said process region and connected to said third and fourth openings, whereby to provide a second closed torroidal path, said second torroidal path extending outside of said vacuum chamber through said second conduit and extending across said process region between said third and fourth openings in a direction transverse to said first torroidal path;
• and
• a magnet for controlling radial distribution of plasma ion density in said processing region, said magnet comprising an elongate pole piece defining a pole piece axis intersecting said processing region.

A plasma reactor comprising:

• a vacuum chamber defined by an enclosure including a side wall and a workpiece support pedestal within the chamber defining a processing region overlying said pedestal, said chamber having at least a first pair of ports through said enclosure near opposing sides of said processing region;
• a first external reentrant tube connected at respective ends thereof to said pair of ports;
• process gas injection apparatus;
• a first RF power applicator coupled to said reentrant tube for applying plasma source power to process gases within said tube to produce a first reentrant torroidal plasma current through said first tube and across said processing region;
• wherein said processing region has a processing region diameter and each of said tubes has a width less than said processing region diameter, said reactor further comprising:
• respective tube termination sections at respective ends of each of said tubes, each tube termination section having a width greater than the width of the respective tube;
• respective plasma current flow splitters within respective tube termination sections, each splitter having a shape that promotes a widening of plasma current flow from the respective tube to the tube termination section of greater width.

A plasma reactor comprising:

• a vacuum chamber defined by an enclosure including a side wall and a workpiece support pedestal within the chamber defining a processing region overlying said pedestal, said chamber having at least a first pair of ports through said enclosure near opposing sides of said processing region;
• a first external reentrant tube, connected at respective ends thereof to said pair of ports;
• process gas injection apparatus;
• a first RF power applicator coupled to said reentrant tube for applying plasma source power to process gases within said tube to produce a first reentrant torroidal plasma current through said first tube and across said processing region;
• wherein said processing region has a processing region diameter and each of said tubes has a width less than said processing region diameter, said reactor further comprising:
• respective tube termination sections at respective ends of each of said tubes, each tube termination section having a width greater than the width of the respective tube;
• and
• an insulator between said termination section and said side wall whereby said termination section and said splitter have an RF potential that follows oscillations of an RF potential of said plasma current.

A plasma reactor comprising:

• a vacuum chamber defined by an enclosure including a side wall and a workpiece support pedestal within the chamber defining a processing region overlying said pedestal, said chamber having at least a first pair of ports through said enclosure near opposing sides of said processing region;
• a first external reentrant tube connected at respective ends thereof to said pair of ports;
• process gas injection apparatus;
• a first RF power applicator coupled to said reentrant tube for applying plasma source power to process gases within said tube to produce a first reentrant torroidal plasma current through said first tube and across said processing region;
• wherein said first RF power applicator comprises:
• an RF power source including an impedance match device;
• a torroidal magnetically permeable core around a portion of said first tube;
• a resonant winding around said core comprising plural groups of turns distributed azimuthally about said core, said resonant winding being coupled to said RF power source.

A plasma reactor comprising:

• a vacuum chamber defined by an enclosure including a side wall and a workpiece support pedestal within the chamber defining a processing region overlying said pedestal, said chamber having at least a first pair of ports through said enclosure near opposing sides of said processing region;
• a first external reentrant tube connected at respective ends thereof to said pair of ports;
• process gas injection apparatus;
• a first RF power applicator coupled to said reentrant tube for applying plasma source power to process gases within said tube to produce a first reentrant torroidal plasma current through said first tube and across said processing region;
• and
• radial fins extending from said workpiece support pedestal to said side wall whereby to suppress plasma current flow between opposing ports through a pumping annulus between said pedestal and said side wall.

A plasma reactor comprising:

• a vacuum chamber defined by an enclosure including a side wall and a workpiece support pedestal within the chamber defining a processing region overlying said pedestal, said chamber having at least a first pair of ports through said enclosure near opposing sides of said processing region;
• a first external reentrant tube connected at respective ends thereof to said pair of ports;
• process gas injection apparatus;
• a first RF power applicator coupled to said reentrant tube for applying plasma source power to process gases within said tube to produce a first reentrant torroidal plasma current through said first tube and across said processing region;
• said chamber enclosure comprising a gas distribution plate overlying and facing said workpiece support pedestal, said gas distribution plate comprising a ceiling layer having gas inlet passages therethrough, a gas manifold layer, a gas mixing layer and a gas injection orifice layer;
• said gas distribution plate comprising radially inner and outer zones, said reactor further comprising dual gas feeds connected to respective ones of said inner and outer zones of said gas distribution plate.