Plasma-Polymerized Fluoropolymer Thin Films for Microelectronic Applications

Abstract

The demand for increased signal transmission speed and device density in the next generation of multilevel integrated circuits (ICs) has placed stringent demands on materials performance for such applications as the line-to-line capacitance of interlayer dielectrics (ILD).1 The ‘National Technology Roadmap for Semiconductors (NTRS) -Technology Needs’, released by the Semiconductor Manufacturing Technology Consortium (SEMATECH) and sponsored by the semiconductor industry association (SIA), has defined two critical changes needed for the development of ultra large scale integrated circuits (ULSI): the reduction of resistance (R) and capacitance (C.) The reduction of resistance is underway with the introduction of copper interconnects to replace aluminum. The NTRS has charted the present and future ILD needs.2 The current need is for a permittivity less than 3 that has compatibility with copper and copper processing. A suitable low permittivity material (low k dielectric) for near future needs has yet to be found because, according to NTRS, “Materials that simultaneously meet the electrical, mechanical and thermal requirements have been elusive”. Fluoropolymers have low permittivities but are difficult to process. The authors have investigated fluoropolymer sputtering, spin-cast perfluorinated dioxole polymers, and plasma polymerization in an attempt to produce thin fluoropolymer films.3–11