Steady-state damage profiles due to reactive ion etching and ion-assisted etching

Ion damage of materials due to reactive ion etching and ion-assisted etching is formulated as a dynamic problem involving the etch rate, damage creation due to ions, diffusion, and ion range effects. The differential equation is solved in the steady-state assuming an exponentially decreasing damage creation function. The ratio D/aε, where D is the damage coefficient, a the inherent depth of ion damage, and ε the etch rate is shown to be an important parameter determining the steady-state damage profile. Results are examined for situations in which the parameter is much less than or much greater than unity, corresponding to range- and diffusion-dominated profiles, respectively. In both situations, steady-state damage profiles will be quite sensitive to the etch rate of the surface. We suggest some experiments which may elucidate the separate contributions of ion channeling and diffusion to observed damage depth profiles.