Contact improvement by employing a conductive sacrificial layer

摘要

A method for improving contact-to-diffusion by lessening the damage caused by oxide sputtering on the contact bottom includes depositing a sacrificial thin conductive polysilicon layer into the contact hole to prevent sputtering of the exposed oxide onto the bottom of the contact-to-diffusion. The polysilicon is kept thin enough to allow maximum consumption of this sacrificial layer during a subsequent Ti-silicidation process. The poly deposition process produces a conformal layer of conductive polysilicon that is not detrimental to the integrity of the contact. A higher level of contact reliability results when this sacrificial layer is employed.