Plasma reactor with overhead RF electrode tuned to the plasma with arcing suppression

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support;
• an RF power generator for supplying power at a frequency of said generator to said overhead electrode and capable of maintaining a plasma within said chamber at a desired plasma ion density level;
• said overhead electrode having a capacitance such that said overhead electrode and the plasma formed in said chamber at said desired plasma ion density resonate together at an electrode resonant frequency, said frequency of said generator being at least near said electrode-plasma resonant frequency;
• an insulating layer formed on a surface of said overhead electrode facing said workpiece support;
• a capacitive insulating layer between said RF power generator and said overhead electrode;
• a metal foam layer overlying and contacting a surface of said overhead electrode that faces away from said workpiece support.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support;
• an RF power generator capable of supplying power to said overhead electrode to maintain a plasma in said chamber at a desired plasma ion density;
• a strip line circuit having a near end thereof adjacent said overhead electrode for coupling power from said RF power generator to said overhead electrode and providing an impedance transformation therebetween, said strip line circuit comprising:
• a strip line conductor generally above said overhead electrode and connected at a near end thereof to said overhead electrode,
• a ground plane conductor above said overhead electrode and spaced from said inner conductor along the length thereof and connected to an RF return potential of said RF power generator,
• a tap at a selected location along the length of said strip line conductor, said tap comprising a connection between said strip line conductor and an output terminal of said RF power generator.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support;
• an RF power generator and an impedance matching element coupled between said overhead electrode and said RF power generator;
• an insulating layer formed on a surface of said overhead electrode facing said workpiece support;
• a capacitive insulating layer between said impedance matching element and said overhead electrode;
• a metal foam layer overlying and contacting a surface of said overhead electrode that faces away from said workpiece support.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support, said electrode having plural gas injection orifices therein generally facing said workpiece support;
• an RF power generator and an impedance matching element coupled between said overhead electrode and said RF power generator, said impedance matching element having a hollow center conductor connected to said RF power generator and coupled to said overhead electrode;
• and
• at least one gas feed line coupled to said plural gas injection orifices and extending through said hollow center conductor, whereby said gas feed line is electrically shielded by said hollow center conductor.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support, said electrode having plural gas injection orifices therein generally facing said workpiece support;
• an RF power generator and an impedance matching element coupled between said overhead electrode and said RF power generator, said impedance matching element having a hollow center conductor connected to said RF power generator and coupled to said overhead electrode;
• an optical window in said overhead electrode;
• an optical conduit connected at one end thereof to said window and extending through said hollow center conductor of said impedance match element.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support, said electrode having plural gas injection orifices therein generally facing said workpiece support;
• an RF power generator and an impedance matching element coupled between said overhead electrode and said RF power generator, said impedance matching element having a hollow center conductor connected to said RF power generator and coupled to said overhead electrode;
• a metal foam layer overlying said overhead electrode;
• a capacitive insulating layer between said center conductor and said overhead electrode.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support, said electrode having plural gas injection orifices therein generally facing said workpiece support;
• an RF power generator and an impedance matching element coupled between said overhead electrode and said RF power generator;
• an insulating layer formed on a surface of said overhead electrode facing said workpiece support;
• a capacitive insulating layer between said RF power generator and said overhead electrode, whereby said overhead electrode is capacitively isolated from said plasma and from said RF power generator;
• and
• said overhead electrode having a reactance that forms a resonance with the plasma at an electrode-plasma resonant frequency which is at or near said frequency of said generator.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support, said electrode having plural gas injection orifices therein generally facing said workpiece support;
• a VHF power generator and an impedance matching element coupled between said overhead electrode and said RF power generator;
• an HF bias power generator coupled to said workpiece support;
• a capacitive insulating layer between said RF power generator and said overhead electrode and having a capacitance that provides an RF return path from said plasma to said overhead electrode that is resonant at least near the HF frequency of said HF bias power generator and that has a negligible impedance at VHF frequencies.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support, said electrode having plural gas injection orifices therein generally facing said workpiece support, said orifices comprising a radially inner group thereof and a radially outer group thereof;
• an RF power generator and an impedance matching element coupled between said overhead electrode and said RF power generator;
• radially inner and outer gas baffling layers within said overhead electrode coupled to respective ones of said radially inner and outer groups of orifices
• first and second gas feed lines coupled to said radially inner and outer gas baffling layers respectively, said first and second gas feed lines being connectable to independently adjustable process gas sources for separate adjustment of gas flow rates at radially inner and outer locations.

A plasma reactor for processing a semiconductor workpiece, comprising:

• a reactor chamber having a chamber wall and containing a workpiece support for holding the semiconductor workpiece;
• an overhead electrode overlying said workpiece support, said electrode being provided with an insulative surface and plural gas injection orifices generally facing said workpiece support;
• an RF power generator for supplying power at a frequency of said generator to said overhead electrode and capable of maintaining a plasma within said chamber at a desired plasma ion density level;
• a fixed impedance matching element connected between said generator and overhead electrode,
• a capacitive insulating layer between said matching element and said overhead electrode;
• a metal foam layer overlying and contacting a surface of said overhead electrode that faces away from said workpiece support.