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Coil configurations for improved uniformity in inductively coupled plasma systems

  • US 5,401,350 A
  • Filed: 03/08/1993
  • Issued: 03/28/1995
  • Est. Priority Date: 03/08/1993
  • Status: Expired due to Term
First Claim
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1. An apparatus for producing a uniformly planar plasma in an inductively coupled plasma system comprised of an enclosure having side walls and a radio frequency transparent face substantially perpendicular to the side walls, means for supplying process gas to be ionized into plasma in the interior of the enclosure, and an interior surface of the enclosure adapted to hold a work piece substantially parallel to the ion plasma flow, said apparatus comprising:

  • a coil having a variable pitch spiral winding wherein the spacing between the turns of the winding is widest near the center of said coil and the spacing between the turns of the winding progressively decrease away from the center of said coil such that the spacing between the turns of the variable pitch spiral winding is narrower toward the outside radius of said coil than toward its center;

    said coil being proximate to the transparent face of the enclosure; and

    said coil arranged for connection to a radio frequency power source.

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