Functional separation of biasing and sustaining voltages in two-frequency capacitively coupled plasma

T. Kitajima, Y. Takeo, Z. Lj Petrović, T. Makabe

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Abstract

Separation of the effects of rf sources used for biasing the wafer and for sustaining the plasma is studied by measuring the space profiles of net excitation rate of Ar(3p5) for a two-frequency capacitively coupled plasma as a representation of a typical oxide etcher. Measurements were performed in Ar and in CF4/Ar mixtures. For biasing supply operating at low frequency, 700 kHz, it was shown that the effect of the voltage becomes significantly smaller as the sustaining voltage is changed from high frequency, 13.56 MHz, to very high frequency (VHF), 100 MHz, and it even disappears for pulsed operation in mixtures. This is the result of the low dc self-bias at the VHF electrode that allows the high energy secondary electrons to leave the plasma without excessive contribution to ionization and dissociation.

Original languageEnglish
Pages (from-to)489-491
Number of pages3
JournalApplied Physics Letters
Volume77
Issue number4
DOIs
Publication statusPublished - 2000 Jul 24

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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