Profile evolution during pulsed plasma etching

Evolution of etched profiles has been studied numerically during pulsed low-pressure; high-density plasma etching of Si in Cl-2. The time-dependent behavior of chlorinated surface coverage and etch rate was calculated assuming Langmuir adsorption kinetics. Etched profiles were then simulated using the time-averaged etch rates obtained, to examine etch anisotropy and microscopic uniformity. The model predicted that under pulsed plasma conditions. the surface coverage is increased at the bottom of microstructures, resulting in highly anisotropic, aspect-ratio independent etching.