Feature scale transport and reaction during low-pressure deposition processes

Abstract

This chapter focuses on feature scale transport and explains the reaction in features on patterned wafers during low-pressure processing. The theory for transport and reaction is valid for both deposition and etch processes; however, the examples focus on deposition processes. The goal of transport and reaction modeling and simulation is to develop and validate models, which in turn provide a unified understanding of film profile evolution. Further, the chapter discusses “continuum” models of film profile evolution, which might be important to the performance of polycrystalline films. The chapter provides a review of basics of chemistry and free molecular transport, and the ballistic transport and reaction model (BTRM) valid for low-pressure deposition (and etch) processes inside micron scale features on patterned wafers. The chapter also discusses how studies that combine experiments and simulations are being used to help develop constitutive properties for selected low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD), and physical vapor deposition (PVD) systems. For PVD processes, a study of curvature-driven diffusion is discussed. The chapter further presents the results of a combined simulation and experimental study of feature scale composition nonuniformities in the sputter deposition (PVD) of titanium-tungsten films. An example of how feature scale simulations can be used to guide process design is also given.