Femtosecond pulsed laser ablation and deposition of thin films of polytetrafluoroethylene

Abstract

A Ti:Sapphire (IR, 800 nm) femtosecond pulsed laser was used to deposit thin films (<1 μm) of polytetrafluoroethylene (PTFE) on single crystal silicon (1 0 0) wafers. Scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and IR spectroscopy were used to characterize the structure, composition, and properties of PTFE films. Results showed that the femtosecond pulsed laser ablates the target cleanly and precisely compared to the traditional nanosecond pulsed (248-nm excimer) laser. The deposition rate was higher and the film quality (particulate density, stochiometry, and smoothness) was superior to the excimer laser-deposited films. The films exhibited crystalline structures with a chemical composition same as the bulk target. High quality ablation and deposition of PTFE by the high-intensity femtosecond pulsed laser are attributed to the multiphoton absorption and high kinetic energy of species emitted from the target, implying that the femtosecond pulsed laser is a most promising tool for microfabrication of PTFE.