Electron cyclotron resonance plasma source and method of operation

An electron cyclotron resonance (ECR) plasma source for use in treating specimens by processes including chemical vapor deposition and etching, comprising

• a cylindrical chamber which is symmetrical about its longitudinal axis,
• means for supporting a specimen adjacent one axial end of the cylindrical chamber,
• means for introducing a gaseous medium into the chamber,
• two cylindrical magnet assemblies arranged circumferentially about the chamber for generating a circumferentially continuous and symmetrical magnetic field having lines of force forming continuous annular lobes also circumferentially extending about the chamber and continuous resonant interaction regions encircling the longitudinal axis of the chamber adjacent an opposite axial end thereof,
• means for developing a substantially field free region adjacent the one axial end of the chamber while minimizing extension of magnetic field force lines into the magnetic field free region and toward the specimen,
• a microwave power applicator arranged between the magnet assemblies and comprising at least one pair of slotted waveguide antennae each formed in an arcuate configuration, the paired antennae each having an injection axis extending radially inwardly toward the longitudinal axis of the chamber for uniformly radiating electromagnetic radiation toward the resonant interaction region about the entire periphery of the chamber so that plasma electrons made energetic by interaction with the electromagnetic radiation are not permitted line-of-sight communication to the specimen along field force lines in the magnetic field free region, and
• means for maintaining low gas pressure in the chamber,
• whereby a plasma stream flows through the magnetic field free region toward the specimen with characteristics of high plasma density, uniformity over transverse dimensions larger than the specimen, low plasma temperature and absence of energetic particles resulting from plasma instabilities even with operating gas pressures as low as 10.sup.-5 Torr.

An electron cyclotron resonance (ECR) plasma source for use in treating specimens by processes including chemical vapor deposition and etching, comprising

• a cylindrical chamber which is symmetrical about its longitudinal axis,
• means for supporting one of the specimens adjacent one axial end of the cylindrical chamber,
• means for introducing a gaseous medium into the chamber,
• two cylindrical magnet assemblies arranged circumferentially about the chamber for generating a circumferentially continuous and symmetrical magnetic field having lines of force forming continuous annular lobes also circumferentially extending about the chamber and continuous resonant interaction regions encircling the longitudinal axis of the chamber adjacent an opposite axial end thereof,
• means for developing a substantially field free region adjacent the one axial end of the chamber while minimizing extension of magnetic field force lines into the magnetic field free region and toward the specimen,
• a microwave power applicator arranged between the magnet assemblies and having multiple injection axes extending radially inwardly toward the longitudinal axis of the chamber and thereby radiating electromagnetic radiation toward the resonant interaction region about the entire periphery of the chamber,
• means for maintaining low gas pressure in the chamber, and
• means associated with the permanent magnets for final adjustment of the magnetic field configuration,
• whereby a plasma stream flows through the magnetic field free region toward the specimen with characteristics of high plasma density, uniformity over transverse dimensions larger than the specimen, low plasma temperature and absence of energetic particles resulting from plasma instabilities even with operating gas pressures as low as 10.sup.-5 Torr.