Low dielectric-constant insulators for electronics applications

The decreasing device geometry and the increasing use of portable electronics have escalated the need to reduce the capacitance of electronic devices so that higher speed, less crosstalk and lower power consumption can be achieved. High porosity SiO₂ (silica xerogel) and Teflon® AF are two examples that show the challenges in introducing new intermetal dielectrics into VLSI interconnect structures. Teflon® AF and crack-free silica xerogel films have been grown by spin-coating and show dielectric constants of 1.9 and 1.14-1.56 (at optical frequency), respectively. The growth processes and the film characteristics are discussed.