FINE CONTACT HOLE ETCHING IN MAGNETOMICROWAVE PLASMA

Characteristics of fine contact hole etching have been investigated in hydro-fluorocarbon magneto-microwave plasma focusing oil the z component of the gradient of magnetic field at 0.0875 T (dB/dz) and peak-to-peak voltage of RF bias (V(pp) as parameters. Decrease of dB/dz drastically decreases the etch rate of boro-phospho silicate glass (BPSG), critical dimension loss (defined as diameter of the top of contact hole minus diameter of the bottom of resist) and selectivity over heavily doped n-type polycrystalline silicon (n+ poly Si) and resist in fine contact holes. The changes of etching characteristics are correlated with neither F/C ratio nor C1s spectrum of deposited film, but with deposition rate in the region of high V(pp), which presumably respects the change of incident CF(m)+ ion species with dB/dz.