Fundamental Vacuum Beam Studies of Radical-Surface Interactions in Radically Enhanced Atomic Layer Deposition (RE-ALD)

摘要

As device dimensions continue to shrink and aspect ratios continue to increase in microelectronics manufacturing, it will become increasingly important to deposit highly conformal thin films for applications such as Cu diffusion barrier layers. Atomic Layer Deposition (ALD) has been proposed as one way to deposit highly conformal thin films for Cu diffusion barriers due to the self-limiting, layer-by-layer growth that can be achieved with this technology. One problem with thermally activated ALD is that the deposition temperatures that are required to achieve reasonable growth rates and good quality films with low impurity concentrations can be relatively high. This may make the integration of these barrier films with temperature-sensitive films, such as organic low-k films, impossible. One potential alternative to thermal ALD is to use more reactive species such as radicals to catalyze film deposition at lower substrate temperatures. In this work, TiN films are deposited using Radical Enhanced Atomic Layer Deposition (RE-ALD) using separate pulses of TiCl{sub}4, then deuterium radicals, and finally nitrogen radicals. By directing independent beams of each of these species at a given surface (in this case, silicon coated on Quartz Crystal Microbalances), kinetic parameters of interest such as the sticking and reaction probabilities of these species have been measured as a function of surface temperature. Ex-situ XPS analysis of the deposited films will be presented, paying particular attention to the low residual chlorine content that can be achieved with sufficient deuterium radical exposure (～0.3%) at deposition temperatures as low as 100°C. We will also present extensive characterization of the initial nucleation of the film, in particular focusing on the nitrogenation of the substrate that occurs during the initial steps of the RE-ALD process. We shall also discuss characterization of the properties of the deposited film.