We have demonstrated that high-efficiency in situ chamber cleaning wit
h high gas flow rate is possible for SiO2 reactive-ion-etching chamber
s by use of NF3 plasma. The plasma of NF3 gas, which has a low bond en
ergy, can generate a high density of ions and radicals with low kineti
c energy. The cleaning efficiency of several halogenated-gas plasmas h
as been evaluated based on extracted-plasma-parameter analysis. In thi
s analysis important plasma parameters, such as ion energy and ion flu
x density, could be extracted from a simple rf waveform analysis at th
e excitation electrode. The accuracy of this technique has been confir
med with a newly developed rf-plasma direct probing method. Furthermor
e, the waveform of the rf-excited plasma potential has been directly m
easured by the rf-plasma probing method, which has clarified the relat
ionship between the plasma potential and the rf electrode voltage.