Neutral uniformity and transport mechanisms for plasma etching

Dissociated neutral (radical) uniformity on the wafer has been studied in a high-density large area plasma reactor. Radial profiles of radicals on the wafer are measured by scanning optical probe and by spatially resolved act inometry and are also estimated by a simple analytic model and two-dimensio nal (2D) commercial fluid simulation code. Center-peaked radial profiles of radical species are observed experimentally and are also predicted by simp le calculation and by simulation code. The radial radical density profiles are compared with the radial profiles of etching rate of blanket photoresis t films on 200 mm wafers etched by oxygen plasmas. Radial profiles of etch rate and atomic oxygen radical densities are compared and discussed along w ith other parameters such as the profiles of ion density, ion energy, and w afer temperature with various chuck bias voltages. At low chuck bias voltag e the etch rate uniformity is correlated with radical uniformity. As the ch uck bias voltage increases, the etch rate profile begins to follow the ion density profile. (C) 2001 American Institute of Physics.