Patent ID: 8920600

Claim:
An apparatus for processing a substrate using an inductive plasma, the apparatus comprising: a processing chamber having an interior operable to confine a process gas; a substrate holder in the interior of the processing chamber operable to hold a substrate; a plurality of elongated narrow thin dielectric windows on a wall of the chamber, operable to transmit radiofrequency magnetic flux into the chamber and to isolate a source of the magnetic flux from the process gas, each of the windows having a transverse dimension substantially smaller than a span of the chamber and being less than approximately five millimeters in thickness; an inductive plasma applicator disposed external to the chamber and operable to maintain a substantially inductive plasma wholly within the process gas in the interior using radiofrequency power, the applicator comprising a plurality of elongated inductive coupling elements, each of the plurality of inductive coupling elements being adjacent to one of the plurality of dielectric windows; wherein: each inductive coupling element includes a flat coil and a U-shaped magnetic flux concentrator of ferromagnetic material, the flat coil comprising a plurality of coil turns spanning a lateral width, the magnetic flux concentrator operable to focus radiofrequency magnetic flux, the magnetic flux concentrator having a U-shaped transverse cross section of magnetically permeable material that is generally concave in a direction facing the chamber and includes laterally disposed extremities extending toward the chamber interior and to within approximately five millimeters of the chamber interior, the magnetic flux concentrator positioned over the entire lateral width of the flat coil; wherein each inductive coupling element is operable to circulate a radiofrequency magnetic flux emanating from one of the extremities of the included magnetic flux concentrator directionally into the chamber through the adjacent thin window, the magnetic flux emerging generally perpendicular to the adjacent window into a localized space extending from the adjacent window perpendicularly into the chamber, and returning back through, and generally perpendicular to the adjacent window from the localized space to another extremity of the included magnetic flux concentrator.