Insulation and passivation properties of vapor-deposited fluorinated polymer thin films

The use of polymers as electrical insulator has been one of the most common applications, but holds an important key for future high-speed microelectronics devices. Thin films of low dielectric constant and high insulation capability are required to minimize the signal propagation delay in the integrated circuits. Among all the solid materials, fluorinated polymers have the lowest dielectric constant. They also have high dielectric breakdown strength, low dissipation, and high chemical stability. These properties make the fluorinated polymers attractive as the insulating layer for high-speed integrated circuits. One of the difficulties associated with the fluorinated polymers is their poor processability for thin films due to the insoluble nature. We have investigated the possibility of film formation of a fluorinated polymer by the physical vapor deposition (PVD) method. Although PVD requires costly apparatus compared to the common wet processes, it has the advantage of forming uniform thin films with little incorporation of impurities. Film thickness control and multilayer construction are much easier compared to the wet processes. This paper describes the electrical insulating properties and chemical stability of Teflon AF (DuPont) thin films.