Chapter 8 - Spin-on Si-based low-k materials

Abstract

The chapter provides an overview of silsesquioxane (SSQ) materials, and introduces deposition, properties, and selected integration results of porous SiO2 like films. All materials described are based on silicon and deposited by using the spin-on process. The review on SSQ materials includes polymerization and integration issues of various types of SSQ. Different suppliers of precursors for depositing SSQ based low-kdielectrics are also summarized. The SiO2-like porous dielectrics are introduced via a short excursion to fundamentals related to introduction of porosity to dielectric materials. In this context, the chapter examines the routes to deposit this group of low-κ dielectric films using spin-on processing before focusing on the deposition and hydrophobisation post-treatment of SiO2 aerogel thin films. The chapter also explains the main film properties required for the integration by highlighting film morphology, chemical composition and structure, electrical, mechanical, and thermal properties. Dependence of properties on different porosities is also illustrated and the basic material and process compatibility issues are discussed for the porous SiO2aerogel films. This comprises lithography compatibility, cap layer and hard mask deposition, etching, diffusion barrier deposition and chemical mechanical polishing of Copper at the porous films.