HP Labs Technical Reports

Semiconductor Damage from Inert and Molecular Gas Plasmas

Seaward, Karen L.; Moll, N. J.

HPL-91-104

Keyword(s):

Abstract: The change in sheet conductivity of a thin, highly-doped layer of GaAs is measured after exposure to inert gas plasmas (He, Ar, and Xe) and to molecular gas plasmas (CCl sub2 F sub2, CF sub4, SF sub6, and O sub2) in a parallel-plate rf discharge. In order to compare these data, the change in sheet conductivity is converted to a damage depth scale. A different linear relationship is found for the damage dependence on the rf-induced dc bias for each plasma. An inverse-mass relationship is derived from the data for He, Ar, and Xe plasma exposures. Using this, two models are tested for their ability to predict the damage from the molecular gas plasmas. Only the lightest ion(s) present in the molecular gas plasmas appear to cause the measured damage effect. In mixtures of inert and molecular gas plasmas, the inert ions were not always observed. Such data lead to a general conclusion that ions with high ionization potnetials will be quenched in plasmas that also contain gases with low ionization potentials.

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