The electrostatic nature of contaminative particles in a semiconductor processing plasma

Two models are presented to describe the immediate environment surrounding negatively charged contaminants in an idealized argon plasma. The first model uses Poisson’s equation to determine the contaminant charge and voltage. This model predicts a critical radius of the order of the Debye length below which Poisson’s equation is no longer valid. Below the critical radius and for contaminant radii much less than the Debye length, the Coulomb potential is used to find the contaminant charge and voltage. Both models predict negative charges on the order of 10−14 C, and voltages on the same order of magnitude as the electron energy.