MAGNETICALLY CONFINED INDUCTIVELY-COUPLED PLASMA-ETCHING REACTOR

A planar radio frequency (rf) inductively coupled plasma etching syste m has been constructed. The plasma is confined by an external multidip ole magnetic bucket made of Nd-Fe-B magnets. This magnetically confine d inductively coupled plasma system is equipped with a helium backside -cooled electrostatic wafer chuck and a loadlock chamber. A single-sid ed planar Langmuir probe was used to map electron velocity distributio n functions (EVDFs) radially and axially for both Ar and N-2 plasmas w ith rf power up to 1 kW at low pressure (2 mTorr). By rotating the sin gle-sided probe, the authors found that the EVDFs are noticeably aniso tropic. The values of the plasma potential, which were highly uniform radially, were independent of the probe orientation, but those of the floating potential depended strongly on it. The radial uniformity and the absolute magnitude of the plasma potential are confirmed by measur ements using an emissive probe. The Langmuir probe measurements showed some deviations from Maxwellian EVDFs for both Ar and N-2 plasmas. Be cause of the multidipole confinement the plasma densities are quite un iform axially, and the radial uniformity improves as the axial distanc e from the quartz window increases. The rf plasma potential fluctuatio ns were also measured, using a capacitive probe. (C) 1995 American Vac uum Society.