ATOMIC-LAYER ETCHING OF GE USING AN ULTRACLEAN ECR PLASMA

Self-limited atomic-layer etching of Ge(100) has been investigated by alternated chlorine adsorption and Ar+ ion irradiation using an ultrac lean ECR plasma. With short Ar+ ion irradiation, about a quarter of at omic-layer thickness was etched in each cycle under the saturated adso rption condition, which corresponds with the case of Si(100). With inc reasing irradiation amount of Ar+ ions, the etch rate per cycle increa ses and tends to saturate to the atomic-layer thickness of Ge(100). Ta king Ar+ ion induced reaction into consideration, a simple exponential ly-saturating equation well describes the atomic-layer etch rate of Ge . From measured Ar+ ion flux density distribution, it is estimated tha t the energy of Ar+ ions predominantly contributing to the atomic-laye r etching of Ge is higher than the order of similar to 13 eV.