Continuity and morphology of TaN barriers deposited by Atomic Layer Deposition and comparison with physical vapor deposition

Abstract

“Continuity and Morphology of TaN barriers deposited by Atomic Layer Deposition and Comparison with Physical Vapor Deposition”: After barrier deposition the samples were exposed to a HF solution at various concentrations and various exposure times and analyzed by cross-sectional Scanning Electron Microscopy analysis in order to reveal any discontinuities in the barrier films. A comparison has been made between SIP and SIP EnCoRe ionised Physical Vapour Deposition (PVD) and two ALD approaches: ALD only and ALD-etch-ALD. The ALD barrier does not show evidence of pinholes after being subjected to the etching test. The results from this etching test indicate that a 20 cycle ALD TaN barrier deposited on oxide is continuous and free from pinholes. The SIP EnCoRe barrier outperforms the SIP barrier with respect to Barrier continuity. The step coverage and conformality of the ALD and PVD films were measured with Transmission Electron Microscopy on the same high aspect ratio structures. The study was extended by a top view SEM CD analysis to measure the overhang of barrier and seed film as function of Cu seed bias and underlying barrier. It is shown that a larger process window for the Cu seed deposition exists if the barrier thickness is reduced.