Selective chemical vapor deposition of copper using (hfac) copper(I) vinyltrimethylsilane in the absence and presence of water

Abstract

The selective chemical vapor deposition (CVD) of Cu was studied using (hfac)Cu(VTMS) (hfac  1,1,1,5,5,5-hexafluoro-acetylacetonate; VTMS [ vinyltrimethylsilane) in the absence and presence of water during CVD with SiO 2 surface passivation, derived from the silylating agent hexamethyldisilazane (HMDS), as a function of the nature of the carrier gas, HMDS and water vapor flow rates and chamber pressure. For CVD of Cu in the absence of water, pre-dosing with HMDS in the absence of water gave selective deposition. The deposition was feed rate limited and dense, smooth copper films were deposited selectively at rates of about 600 Å min −1. The selectivity for CVD of Cu in the presence of water depended on the pre-dosing conditions. Pre-dosing with both HMDS and water vapor gave selective deposition at rates of about 1200 Å min −1 in the presence of water, a factor of 2 higher compared with CVD in the absence of water vapor. Dense films with near-bulk resistivities were deposited selectively in the trenches on an underlying tungsten layer at the optimum water vapor flow rate and chamber pressure. Higher water vapor flow rates and chamber pressures resulted in porous, discontinuous films with significantly higher resistivities. An integration scheme utilizing selective CVD of Cu is proposed that allows formation of fully encapsulated copper lines without the need for a copper etch.