Characterization of chlorine discharge and etch selectivity in a magnetically confined ICP tool

Summary form only given, as follows. Plasma uniformity of both charged and neutral particles is characterized by a novel electro-optical probe, that combines a double sided Langmuir probe (Mach probe) and an optical fiber. Spatial distribution of plasma potentials and density, electron energy distribution function, and ion velocities are determined by the Mach probe. The spatially and spectrally resolved optical emission is collected by a collimated optical fiber with a restricted line-of-sight. The spatial distribution of atomic chlorine and the fractional dissociation of chlorine molecule are obtained by actinometry. Real-time etch rate selectivity of unpatterned polysilicon and SiO/sub 2/ thin films is determined within seconds by an in-situ two-color laser interferometer. Single and double point schemes of reflected laser interferometry are used to determine the etch selectivity as a function of tool state parameters. The changes in atomic chlorine density during the time varying process is obtained by xenon and argon actinometry and on-line mass spectrometry measured by a pressure calibrated residual gas analyzer. The difference in etch selectivity of polysilicon to SiO/sub 2/ between simultaneous and separate etch of the two films will be discussed.