Low electron temperature microwave surface-wave plasma (SWP) processing method and apparatus

A method of maintaining a low electron temperature plasma in the vacuum processing of a substrate, comprising:

• supporting a substrate for processing at one end of a vacuum processing chamber with a surface thereof facing a processing volume in the chamber;
• coupling microwave energy into the processing space within the chamber from a surface wave launcher at an end of the chamber opposite the substrate;
• pulsing the microwave energy to the surface wave launcher for coupling a pulsed waveform of the microwave energy into the processing space;
• pulsing inductively coupled radio frequency (RF) energy in synchronism with the pulsing of the microwave energy so that an inductively coupled plasma is present in the processing space at a beginning of each pulse of the pulsed microwave energy;
• and
• controlling the pulsing of the microwave energy and the inductively coupled RF energy to produce in the processing space the inductively coupled plasma having an electron temperature at or below a maximum electron temperature that the microwave energy would produce in the processing space absent the pulsing and is of sufficient density to prevent microwave energy penetration of the substrate.