Chapter 3 - Characterization of low dielectric constant materials

Abstract

This chapter highlights that as the integrated circuit dimensions continue to decrease, resistive–capacitative (RC) delay, crosstalk noise, and power dissipation of the interconnect structure becomes the limiting factors for ultra-large-scale integration of integrated circuits. Materials with low dielectric constant are being developed to replace silicon dioxide as inter level dielectrics. This chapter discusses the general approach to reduce the dielectric constant, emphasizing the correlation of dielectric polarizability with bonding characteristics and the tradeoff of dielectric constant and mechanical properties. It then describes the material characterization techniques, including several recently developed techniques for porous low-materials. The techniques have been applied extensively to evaluate the properties of low-dielectrics. Characteristics of three classes of materials are summarized in this chapter—polymers, silsesquioxianes, and porous dielectrics, focusing on the correlation of molecular structure and material properties. Results from porous organosilicate films reveal that dielectric constant and thermal conductivity scale with the average density of the material, the thermomechanical properties degrade significantly beyond the percolation point when the pores becomes interconnected. This points out the challenge for the development of porous low-dielectric.