Topographic dependence of plasma charging induced device damage

We examine a particular mechanism for surface charging during plasma processing, namely charged particle flux shadowing caused by surface topography. We derive an analytic model for the voltage drop across the gate oxide as a function of electron and ion shadowing and compare this mechanism's potential for inducing device damage to that caused by plasma density non-uniformity. The charge dose magnitude that can result from the shadowing mechanism is shown to be consistent with that required for damage to devices.