ION IMPACT ETCH ANISOTROPY DOWNSTREAM FROM DIFFUSION PLASMA SOURCES

Plasma processing in chambers located downstream from a source are gaining widespread use because they allow etching and deposition with minimal damage. This minimized damage, however, is achieved by using a low ion impact energy, which can lead to a poorer etch anisotropy. The best anisotropy for a given impact energy requires the lowest possible ion temperature. Laser-induced fluorescence measurements show that room temperature ions can be attained using a multidipole-confined discharge. In comparison, ion temperatures downstream from electron cyclotron resonance sources are much hotter, according to recent reports.