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Ceramic showerhead including central gas injector for tunable convective-diffusive gas flow in semiconductor substrate processing apparatus

  • US 10,249,511 B2
  • Filed: 06/27/2014
  • Issued: 04/02/2019
  • Est. Priority Date: 06/27/2014
  • Status: Active Grant
First Claim
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1. An inductively coupled plasma processing apparatus comprising:

  • a vacuum chamber;

    a vacuum source adapted to exhaust the vacuum chamber;

    a substrate support comprising a lower electrode on which a single semiconductor substrate is supported in an interior of the vacuum chamber;

    a ceramic showerhead which forms an upper wall of the vacuum chamber wherein the ceramic showerhead includes a gas plenum in fluid communication with a plurality of showerhead gas outlets in a plasma exposed surface thereof for supplying a process gas as a diffusive gas flow to the interior of the vacuum chamber, a central opening in the ceramic showerhead that extends an entire thickness of the ceramic showerhead and the ceramic showerhead including a lower vacuum sealing surface which surrounds the plasma exposed surface and forms a vacuum seal with a vacuum sealing surface of the vacuum chamber;

    a central gas injector disposed in the central opening of the ceramic showerhead, wherein the central gas injector includes one or more gas injector outlets, in a surface thereof that is exposed inside the vacuum chamber, for supplying the process gas as a convective gas flow to the interior of the vacuum chamber at least in a direction towards a center of the semiconductor substrate, whereinthe one or more gas injector outlets include a plurality of central gas outlets, wherein the plurality of central gas outlets are arranged to supply the process gas as the convective gas flow directly from the central gas injector into the vacuum chamber without passing through the gas plenum of the ceramic showerhead, andthe one or more gas injector outlets include a plurality of radial gas outlets arranged radially outward of the plurality of central gas outlets, wherein the plurality of radial gas outlets are arranged to supply the process gas as the diffusive gas flow radially outward from the central gas injector into the gas plenum of the ceramic showerhead and through the plurality of showerhead gas outlets;

    an RF energy source which inductively couples RF energy through the ceramic showerhead and into the vacuum chamber to energize the process gas into a plasma state to process the semiconductor substrate; and

    a control system configured to (i) control supply of the process gas as the convective gas flow through the central gas outlets via a first gas line at a first flow rate and (ii) control supply of, independently of the convective gas flow, the process gas as the diffusive gas flow through the showerhead gas outlets via a second gas line at a second flow rate, wherein the convective gas flow and the diffusive gas flow are supplied simultaneously, and wherein, to control the supply of the convective gas flow and the diffusive gas flow, the control system is further configured to select and control a pressure within the vacuum chamber, the first flow rate, and the second flow rate based on a desired eddy current above the semiconductor substrate, wherein, to achieve the desired eddy current, the control system is configured to independently control the first flow rate and the second flow rate.

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