Abstract: The relations between the parameters of plasma and those of RF power and gas flow were analyzed under the conditions of over etch step in semiconductor plasma etching,by Langmuir probe.The results show that as the RF power was increasing,the RF couple coefficient was comparatively stable.When in a local heating state,most of the electrons were in an adhesive status.The distribution of power couple space in the chamber can be improved as the RF power increases.These results can help to develop plasma dry etching.

Key words: plasma,  sheath theory,  dry etching,  Langmuir probe