Plasma treatment was introduced in order to control the catalytic properties of iodine in catalyst-enhanced chemical vapor deposition (CECVD) of copper (Cu). The iodine adatoms are deactivated (i.e., lose their catalytic effect) by forming Cu-I bonds through reaction with Cu atoms by the bombardment of ions during the plasma treatment. The surface concentration of effective iodine adatoms that can act as catalysts decreases exponentially with an increasing of ion exposure which is the product of ion flux and plasma treatment time. The deactivated iodine can be reactivated by annealing above 200 C. The enhancement factor, defined as the ratio of the enhanced deposition rate of Cu film by the adsorbed iodine to the deposition rate without the catalytic effect of iodine, is proportional to the surface concentration of effective iodine adatoms. The distribution of the surface concentration of effective iodine adatoms inside the trench can be controlled by the plasma treatment. CECVD coupled with plasma treatment enables void-free filling of deep trenches with an aspect ratio of 14.

The mechanism behind super-filling of high-aspect-ratio features with Cu by catalyst-enhanced chemical vapor deposition (CECVD) coupled with plasma treatment is described and the metrology required to predict the filling feasibility is identified and quantified. The reaction probability of a Cu precursor was determined as a function of substrate temperature. Iodine adatoms are deactivated by the bombardment of energetic particles and also by the overdeposition of sputtered Cu atoms during the plasma treatment. The degree of deactivation of adsorbed iodine was experimentally quantified. The quantified factors, reaction probability and degree of deactivation of iodine were introduced to the simulation for the prediction of the trench filling aspect by CECVD coupled with plasma treatment. Simulated results show excellent agreement with the experimental filling aspects.