Feature evolution simulations of copper seed layer deposition using atomic-level particle scattering information

One of the most important processing steps during copper metallization is t he deposition of a thin yet conformal copper seed layer, often using ionize d physical vapor deposition, prior to electroplating, A key need in designi ng this step is assuring that copper of sufficient thickness is deposited a t all points within a high aspect ratio (AR) feature. In this work, we pres ent feature evolution simulations of copper seed layer deposition, using io n reflection and neutral copper sputtering distributions calculated using m olecular dynamics simulations. Independent variables in the model include n eutral-ion and ion-ion flux ratios as well as substrate bias voltage. We sh ow that trenches of AR = 5 can be conformally lined with proper variation o f these independent variables using a simple composition and ion energy cyc ling strategy. Furthermore, we show that the use of reflection and sputteri ng distributions obtained by molecular dynamics simulation results in quali tatively different feature shape predictions than when using isotropic (cos ine) sputtering distributions with no possibility of ion reflection, with t he degree of difference a function of the ion-neutral flux ratio and the io n energy.