Charge Build-Up in Magnetron-Enhanced Reactive Ion Etching

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Abstract
Charge build-up in magnetron-enhanced reactive ion etching (MERIE) was evaluated with metal nitride oxide semiconductor (MNOS) capacitors. In static magnetic field, negative flat band voltage (V fb) shifts of more than -1.5 V were observed in the area under high-density plasma, and more than 2-V V fb shifts were observed at the edge of the wafer near the N and S poles. This distributed V fb shift was considered to result from nonuniform plasma potential caused by secondary electron E×B drift motion. In rotated magnetic field, V fb shifts were reduced. No significant V fb shifts were observed when the magnet was rotated at 120 rpm. The V fb shift reduction in rotated magnetic field was supposed to result from charge neutralization by alternate charge build-up.