Multi-zone RF electrode for field/plasma uniformity control in capacitive plasma sources

Apparatus for generating and controlling a plasma, comprising:

• a capacitively coupled plasma source composed of a plasma electrode and a bias electrode, said plasma electrode being composed of a plurality of sub-electrodes which are electrically insulated from one another and said plasma electrode being spaced from said bias electrode by a plasma region in which the plasma is formed;
• and
• RF power supply means connected to said sub-electrodes for coupling RF power into the plasma region via said sub-electrodes to generate and sustain the plasma,
• wherein said RF power supply means are operative for causing the RF power coupled via one of said sub-electrodes to be able to differ in at least one of frequency, phase and waveform from the RF power coupled via another one of said sub-electrodes.

Apparatus for generating and controlling a plasma, comprising:

• a capacitively coupled plasma source composed of a plasma electrode and a bias electrode, said plasma electrode being composed of a plurality of sub-electrodes which are electrically insulated from one another and said plasma electrode being spaced from said bias electrode by a plasma region in which the plasma is formed;
• RF power supply means connected to said sub-electrodes for coupling RF power into the plasma region via said sub-electrodes to generate and sustain the plasma;
• and
• a plurality of tuned filters each connected to a respective one of said sub-electrodes for attenuating an electric field component in the plasma region at a specific harmonic of the RF power supplied to the plasma region.

A method for generating and controlling a plasma formed in a capacitively coupled plasma source having a plasma electrode and a bias electrode, the plasma electrode being composed of a plurality of sub-electrodes that are electrically insulated from one another and the plasma being formed in a plasma region between the plasma electrode and the bias electrode, the plasma being coupled to each sub-electrode so that a respective plasma impedance value is observed at each sub-electrode, said method comprising:

• coupling RF power to the plasma via each sub-electrode by supplying RF power to each sub-electrode via a respective controllable match network from a respective controllable power source;
• adjusting each match network to have an output impedance that is matched to the respective plasma impedance value observed at the respective sub-electrode;
• and
• adjusting the RF power supplied by each power source in a direction to cause the respective plasma impedance value observed at each sub-electrode to have a respective reference value.

A method for determining reference values for plasma impedance as observed by each of a plurality of individual subelectrodes of a plasma electrode in a capacitively coupled plasma source, said method comprising:

• operating the plasma source under a succession of different sets of operating conditions;
• during operation under each set of operating conditions, measuring plasma impedance as observed at each sub-electrode and a selected parameter of the plasma adjacent each sub-electrode;
• determining which one of the different sets of operating conditions produces the most desirable values for the selected parameter of the plasma;
• and
• selecting, as the reference values, the measured plasma impedance associated with the set of operating conditions determined to produce the most desirable values for the selected parameter of the plasma.

Apparatus for generating and controlling a plasma, comprising:

• a capacitively coupled plasma source composed of a plasma electrode and a bias electrode, said plasma electrode being composed of a plurality of sub-electrodes which are electrically insulated from one another and said plasma electrode being spaced from said bias electrode by a plasma region in which the plasma is formed, each of said sub-electrodes being provided with a plurality of gas flow passages communicating with the plasma region;
• RF power supply means connected to said sub-electrodes for coupling RF power into the plasma region via said sub-electrodes to generate and sustain the plasma;
• and
• process gas delivery means communicating with said plurality of gas flow passages for supplying process gas to all of said passages.