Paper PS1-ThA10
A New Diagnostic Tool of Radio-Frequency Etching Plasma Produced in Insulated Vessels

Thursday, October 23, 2008, 5:00 pm, Room 304

A new method to measure electron temperature and electron energy distribution function by an emissive probe has been proposed.¹ The method is based on measurement of the functional relationship between the floating potential and the heating voltage of emissive probe. From the measured data of the floating potential change as a function of the heating voltage, the electron temperature could be determined by comparing with the theoretical curve obtained under the assumption of Maxwellian distribution. The overall characteristic of the floating potential change could be explained as a function of the heating voltage. The electron temperatures obtained by the present method were consistent with those measured by the rf-compensated Langmuir probe within the error. These experimental verifications were made in the electron density range of 2.6x10¹¹–2.8x10¹² cm^-3 in an inductively coupled plasma of Ar. In this study, a prototype of the diagnostic tool based on the present method was developed in a computer-aided fashion. The method was also applied to a SF₆ etching plasma which was produced in ceramic discharge tubes by surface-wave with the frequencies of 13.56 and 60 MHz. In this experiment, the Renium filament was employed, and the erectron energy as well as the potentials were measured in SF₆ plasma. These data were found to be consistent with the Si ecth rate obtained in the SF₆ plasma. It was stressed that the present method was advantageous in that the probe is operated in a floating condition, hence applicable to plasmas produced in an insulated container. The electron energy distribution function was also obtained in. SF₆ etching plasma which was produced in ceramic discharge tubes by surface-wave.

¹K. Kusaba and H. Shindo, Review of Scientific Instruments, 78,123503(2007).